CA1309817C - Polyolefin fiber having improved initial elongation and process for preparation thereof - Google Patents
Polyolefin fiber having improved initial elongation and process for preparation thereofInfo
- Publication number
- CA1309817C CA1309817C CA000584905A CA584905A CA1309817C CA 1309817 C CA1309817 C CA 1309817C CA 000584905 A CA000584905 A CA 000584905A CA 584905 A CA584905 A CA 584905A CA 1309817 C CA1309817 C CA 1309817C
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- Canada
- Prior art keywords
- molecular
- ultra
- olefin
- weight
- carbon atoms
- Prior art date
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Classifications
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
- D01F6/02—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
- D01F6/04—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds from polyolefins
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
- D01F6/44—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds as major constituent with other polymers or low-molecular-weight compounds
- D01F6/46—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds as major constituent with other polymers or low-molecular-weight compounds of polyolefins
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F110/00—Homopolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
- C08F110/02—Ethene
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
- Y10T428/2913—Rod, strand, filament or fiber
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
- Y10T428/2913—Rod, strand, filament or fiber
- Y10T428/2929—Bicomponent, conjugate, composite or collateral fibers or filaments [i.e., coextruded sheath-core or side-by-side type]
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T442/00—Fabric [woven, knitted, or nonwoven textile or cloth, etc.]
- Y10T442/10—Scrim [e.g., open net or mesh, gauze, loose or open weave or knit, etc.]
- Y10T442/102—Woven scrim
- Y10T442/153—Including an additional scrim layer
Abstract
POLYOLEFIN FIBER HAVING IMPROVED INITIAL
ELONGATION AND PROCESS FOR PREPARATION THEREOF
Abstract of the Disclosure Disclosed is a polyolefin fiber having an improved initial elongation, which comprises a strongly drawn body of a composition comprising ultra-high-molecular-weight polyethylene and an ultra-high-molecular-weight copolymer of ethylene with an olefin having at least 3 carbon atoms at such a ratio that the content of the olefin having at least 3 carbon atoms in the entire composition is such that the number of side chains per 1000 carbon atoms in the composition is 0.2 to 5.0 on the average, and having an intrinsic viscosity [?] of at least 5 d?/g as the entire composition, wherein the strongly drawn body has at least two crystal melting endothermic peaks, close to each other, in the region of temperatures higher by at least 15°C than the inherent crystal melting temperature (Tm) of the composition determined as the main melting endothermic peak at the second temperature elevation when measured in the restrained state by a differential scanning calorimeter.
ELONGATION AND PROCESS FOR PREPARATION THEREOF
Abstract of the Disclosure Disclosed is a polyolefin fiber having an improved initial elongation, which comprises a strongly drawn body of a composition comprising ultra-high-molecular-weight polyethylene and an ultra-high-molecular-weight copolymer of ethylene with an olefin having at least 3 carbon atoms at such a ratio that the content of the olefin having at least 3 carbon atoms in the entire composition is such that the number of side chains per 1000 carbon atoms in the composition is 0.2 to 5.0 on the average, and having an intrinsic viscosity [?] of at least 5 d?/g as the entire composition, wherein the strongly drawn body has at least two crystal melting endothermic peaks, close to each other, in the region of temperatures higher by at least 15°C than the inherent crystal melting temperature (Tm) of the composition determined as the main melting endothermic peak at the second temperature elevation when measured in the restrained state by a differential scanning calorimeter.
Description
~;3~ 7 POLYOLEFIN FIBER HAVING IMPROVED INITIAL
ELONGATION AND PROCESS FOR PREPARATION THEREOF
back~round of the Invention (1) Fi01d of the Invention The pres0nt invention relates to a high-strength polyolefin fiber having an improved initial elongation and a process ~or the preparation thereo~.
ELONGATION AND PROCESS FOR PREPARATION THEREOF
back~round of the Invention (1) Fi01d of the Invention The pres0nt invention relates to a high-strength polyolefin fiber having an improved initial elongation and a process ~or the preparation thereo~.
(2) Description of the Related Art lQ It is known that a molecularly oriented shaped body having high elastic modulus and high tensile strength is obtained by shaping ultra-high-molecular-weight polyethylene into a fiber, a tape or the like and drawing the shaped body. For example, Japanese Patent Application Laid-Open Specification No. 15408/81 discloses a process in which a dilute solution Q~ ultra-high-molecular-weight polyethylene is spun and the obtained ~ilament is drawn. Furthermore, Japanese Patent Application Laid~Open Speci~ication No. 130313/84 discloses a process in which ultra-high-molecular-~eight polyethylene is melt-kneaded with a wax and tha kneaded mixture is extruded, cooled, solidified and then drawn.
Moreover, Japanese Patent Application Laid-Open Specification No. 187614/84 discloses a process in which a melt-kneaded mixture as mentioned above is extruded, dra~ted, cooled, solidi~ied and then drawn.
If ultra-high-molecular-weight polyethylene is shaped into a ~iber and the Piber i5 strongly drawn, the elastic modulus and tensile strength are increased with increase o~ the draw ratio~ This drawn fiber has good mechanical properties such as high elastic modulus and hlgh tensile strength and is excellent in light weight characteristic, water resistance and weatherability.
However, this drawn fibar is still insu~icient and defectlve in -that the initial elongation is large and 1 ~ ~ q~
the creep resistance is poor.
The initial elongation is a phenomenon which is peculiarly and commonly observed in organic fibers, and this phenomenon is observed even in rigid high polymers such as a Kevlar fiber (wholly aromatic polyamide fiber). Especially in the above-mentioned polyethylene fiber having high elastic modulus and high strength, the initial elongation is so large as about 1~ at normal temperature, and a high elastic modulus cannot be sufficiently utilized in the field of, for example, a composite material or the like. More specifically, influences by this large initial elongation are serious in fiber-reinforced resin composite materials, tension members (optlcal fiber cords) and the like.
Summar~ of the Invention It is therefore a primary object of the present invention to provide a polyolefin fiber which is highly improved in the initial elongation and creepdresistance ?
and has high strength and elastic modulus,&-R~ a process for the preparation of this polyolefin fiber.
More specifically, in accordance with one aspect of the present invention, there is provided a polyolefin fiber having an improved initial elongation, which comprises a strongly drawn body of a composition comprising ultra-hlgh-molecular-weight polyethylene and an ultra-high-molecular-weight copolymer of ethylene with an olefin having at least 3 carbon atoms at such a ratio that the content of the ole~in having at least 3 carbon atoms in tho entire composition is such that the number of side chains per 1000 carbon atoms in the composition is 0.2 to 5.0 on the average, and having an intrinsic viscosity ~) of at least 5 d~/g as the entire compositlon, wherein the strongly dra~n body has at least two crystal melting endothermic peaks, close to each othar, in the region o~ temperatures higher by at , :, least 15 C than the inh0rent crystal melting temperature (Tm) Or the composition determined as the main melting endothermic peak at the second temperature elevation when measured in the res-trained state by a differential scanning calorimeter.
In accordance with another aspect of the present invention, there is provided a process for the preparation of a polyolefin fiber having an improved initial elongaeion, which comprises melt-kneading a composition comprising ultra-high-molecular-weight polyethylene having an intrinsic viscosity ~ of at least 5 d~/g, and an ultra-high-molecular-weight ethylene/~-olefin copolymer having an intrinsic viscosity (~of at least 5 d~/g, said ~-olefin having at least 3 carbon atoms, and having such a content of the 6~-olefin having at least 3 carbon atoms that the number of side chains of thec~-olefin per lO00 carbon atoms in the copolymer is 0.5 to lO on the average, at a weight ratio of from lO/90 to 90/lO, in the presence of a diluent, spinning the kneaded mixture and drawing the obtainad fiber at a draw ratio of at least lO.
When a load corresponding to 30% of the breaking load at room temperature is applied to the polyolefin fiber of the present invention at a sample length of l cm and an ambient temperature of 70 C, the init~al elongation after 60 seconds from the point of the Lnitiation of the load is lower than 5% and the average - creep speed during the perlod of from the point of 90 seconds from the initiation of application of the load to the polnt of 180 seconds from the inltiation of application of the load is lower than l x 10 4 sec 1, These characteristics of the fiber of the present ~nvention are quite surprising.
Brie~ Description o~ the Drawin~s Fig. 1 ~s a graph illustrating the creep :
, characteristics o~ an ultra-high-molecular-weight polyethylene ~iber (~), an ultra-high-molecular-weight ethylene/bu-tene-l copolymer ~iber ~5) and fibers (l) through (3) of compositions of both the polymers.
Figs. 2, 3, 4, 5 and 6 are di~ferential thermal curves of the foregoing samples (l) through (5).
Detailed Description of the Pre~erred Embodimen-ts The present invention is based on the ~inding that a composition comprising ultra-high-molecular-weight polyethylene and an ultra-high-molecular-weight copolymer of ethylene with an ~-olefin having at least 3 carbon atoms (hereinaPter re~erred to as "ultra-hi~h-molecular-~eight ethylene/~-ole~in copolymer") at a certain blend ratio is e~cellent in the spinnability and drawability and can be easily shaped in a strongly drawn shaped body, and this drawn shaped body has vèry high elastic modulus and strength and also has excellent creep resistance and in this drawn shaped body,.the initial elongation is controlled to a very low level.
Ultra-high-molecular-weight polyethylene can be drawn at a high draw ratio and the fiber obtained at a high draw ratio shows high strength and high elastic modulus, but the drawn fiber is de~ective in that the creep resistance is poor. On the other hand, a ~iber o~
an ultra-high-molecular-weight ethylene/~-ole~in copolymer has an excellent creep resistance, but the drawability is not surficient and a yarn having high strength and high elastic modulus can hardly be obtained. A highly drawn ~iber comprising ultra-high-molecular-weight polyethylene and an ultra-high-molecular-weight ethylene/~-ole~in copolymer at a certain weight ratio according to the present invention has high strength and high elastic modulus o~ the former polymer and high creep resistance o~ the latter polymer synergistically and moreover, the initial elongation is .
drastically reduced in this drawn fiber. Thase characteristics are quite surprising.
Fig. 1 illustrates the relation between -the time elapsing after application of the load and the creep elongation, which is observed with respect to various highly drawn polyolefln fibers when a load correspond~ng to 30% of the breaking load at room temperature is applied at a sample length of 1 cm and an ambient temperature of 70 C. In Fig. 1, sample (4) is an ultra-high-molecular-weight polyethylene fiber, sample (5) is an ultra-high-molecular-weight ethylene/butene-1 copolymer fiber, and samples (1), (2) and t3) are fibers of compositions comprising the above-mentioned ultra-high-molecular-weight polyethylene and ultra-high-molecular-weight ethylene/butene-l copolymer at weight ratios of 10/20, 15/15 and 20/10, respectively. In short, the creep characteristics of these fibers are shown in Fig. 1. Incidentally, the respective samples are described in detail in the examples given hereinafter.
From the results shown in Fig. 1, it is seen that in the fiber of the composition of the present invention, the initial elongation (the elongation after 60 seconds from the point of the initiation o~
application of' the load) is controlled to a much lower level even under an accelerated condition of 70 C than in -the fibers composed solely o~ the respective components.
Figs. 2, 3, 4, 5 and 6 are temperature-mslting thermal curves measured by a differential ~canning calorimeter with respect to flbers (multifilaments~ of samples (1) through (5) used for the measurement of Fig.
1 in the ~tate where the sample is wound on an aluminum sheet having a thickness of 0.2 mm and the end is restrained. The crystal melting temperatures (Tm) of ~ 3 ~ 7 samples (1) through (3) according to ~he present invention, as determined as the main melting endo-thermic peak as the second temperature elevation are 135.0 C, 135.6 C and 136.2 C, respectively. Accordingly, it is 5 seen that the ~iber o~ the present invention has, in the restrained state, a crystal ~elting pea~ only in the region o~ temperatures substantially higher by at least 15 C than Tm and this peak appears as at least two peaks close to each other. This crystal melting ?
10 characteristics has a close relation to drastic reduction oP the initlal elongation.
The ~act that in the polyole~in fiber o~ the present invention, the initial elongation is controlled to a very small value by blending the two components was 15 accidentally found as a phenomenon, and the reason i9 still unknowr~. However, it is presumed that the reason will probably be as follows, though the reason described below is not binding one. In general, a drawn fiber has a structure in which the polymer chain passes through a 20 crystalline zone and an amorphous zone alternately and the crystalline zone is oriented in the drawing direction, and it is considered that it is the amorphous zone that has influences on the initial elongation o~
the ~iber. In the polyolefin fiber oP the present 25 invention, since the ~iber comprises ultra-high-molecular-weight polyethylene and an ultra-high-molecular-weight ethylene/~-olefin copolymer, a crystal structure di~erent from the crystal of polyethylene is introduced into the portion to be inherently ~ormed into 30 an amorphous zone or the length of the amorphous zone is shortened. It is considered that for this reason, the ini~ial elongation can be reduced. As pointed out hereinbefore, the results o~ the di~ferential thermal analysis o~ the polyole~in fiber o~ the present 35 invention indicate formation o~ two phases o~ crystals ' :: , ~ 3 ~ 7 differing ln the melting peak.
From the viewpoint of the mechanical propertles of ths fiber, it is important that the polyolefln composition constituting the fiber of the present invention, as a whole, should have an intrinsic viscosity of at least 5 d~/g, especially 7 to 30 de/g.
Since the molecule ends do not participate in the strength of the fiber and the number of the molecule ends is a reciprocal number of the melecular weight (viscosity), it is seen that a highor intrinsic viscosity ~ gives a higher strength.
In the present invention, it is important that the polyolefin composition should comprise the ultra-high-molecular-weight ethylene/~-olefin copolymer ln such an amount that the number of branched chains per 1000 carbon atoms in the composition is 0.2 to 5.0 on the average, especially 0.5 to 3.0 on the average. If tha number of branched chains is too small and below the above-mentioned range, it is difficult to ~orm an internal structure of the fiber effective for reducing the initial elongation and improving the creep resistance. In contrast, if the number of branched chains is too large and exceeds the above-mentioned range, the crystallinity is drastically degraded and it is difficult to obtain high elastic modulus and strength. In the present invention, determination of branched chains o~ the com~os~tion is carried out by Sf ~ C ~ O.~ c~7~ s c ~De using an infrared ~ 3~ (supplied by Nippon Bunko Xogyo). More specifically, the absorbance at 1378 cm 1 based on the deformation vibration o~ the methyl group at the end of the branch of the ~ ole~in introduced in the ethylene chain is measured and the number o~ branched methyl groups per lO00 carbon atoms can be easily obtained from the measured value with reference to a calibration curve prepared in advance by us~ng a model compound in a 13C nuclear magnetic resonance apparatus.
The present invention will now be described in detail.
Starting Materials The ultra-high-molecular-weight polyethylene used in the present invention is known, and any of known polymers can be optionally used. In order to obtain a fiber having high strength and hlgh elastic modulus, it is pre~erred that the intrinsic viscosity o~ the ultra-high-molecular-weight polyethylene be at least 5 dQ/g, especially 7 to 30 dR/g.
From the same viewpoint, the ultra-high-molecular-weight ethylene/~-olefin copolymer as the other component should also have an intrinsic viscosity ~of at least 5 dQ/g, especially 7 to 30 dR/g. What must be taken into consideration here i5 that i~ the difference of the molecular weight between the ultra-high-molecular-weight polyethylene and the ultra-high-molecular-weight ethylene/~-ole~in copolymer is too large, the creep resistance o~ the ~inal ~iber tends to decrease. Accordlngly, it is pre~erred that the di~erence o~ the intrinsic viscosity between both the resins be smaller than 5 d~/g, especially smallar than 3 dQ/g-As the olefin having at least 3 carbon atoms, therecan be used at least one member selected from mono-olefins ~uch as propylene, butene-l, pentene-1, 4-methylpentene-l, hexene-l, heptene-l and octene~l.
Furthermore, hydrocarbons having at least two unsaturated bonds in the molecule, pre~erably at least two double bonds, can b~ used. For example, there can B be mentionedbc ~n ~ ga ed diene type hydrocarbon compounds such as 1,3-~ eR~, 2 methyl-2,4-pentadiens, 2,3=
dimethyl-1,3-butadiene, 2,4-hexadiene, 3-methyl-2,4-' g hexadiene, 1,3-pentadiene and 2-methyl-1,3-bu~adiene, non conjugated diene type hydrocarbon compounds such as 1,4-pentadiene, 1,5-hexadiene t 1,6-heptadiene, 1,7-octadiene~ 2,5-dimethyl-1,5-hexadiene, 4-methyl-1,4-hexadîene, 5-methyl-1,4-hexadiene, 4-ethyl-1,4-hexadiene, 4,5-dimethyl-1,4-hexadiene, 4-methyl-1,4-h0ptadiene, 4-ethyl-1,4-heptadiene, 5-methyl-1,4-heptadiene, 4-ethyl-1,4-octadiene, 5-methyl-1,4-octadiene and 4-n-propyl-1,4-decadiene, conjugated polyolefin type hydrocarbon compounds such as 1,3,5-hexatriene, 1,3,5,7-octatetraene and 2-vinyl-1,3-butadiene, non-conjugated polyole~in type hydrocarbon compounds such as squalene, and divinylbenzene and vinylnorbornene.
The ultra-high-molecular-weight ethylee/~-olefin copolymer used in the present invention is obtained by slurry-polymerizing ethylene and an ~ole~in having at least 3 carbon atoms as the comonomer in an organic solvent by using a Ziegler type catalyst.
In this case, the amount used o~ the olefin comonomer should be such that the number of side chains (branched chains) per 1000 carbon atoms ln the ~inal composition i5 0.2 to 5, especially 0.5 to 3.
The ethylene/~-ole~in copolymer most e~ective ~or attaining the obJect o~ the present invention is an ethylene/butene-l copolymer, and an ethylene/4-methylpentene-l copolymer, an ethylene/hexene-l copolymer, an ethylene/octene-l copolymer, an ethylene/propylene copolymer, an ethylene/propylene/4-methylpentene-l copolymer and an ethylene/1,5-hexadiene copolymer are advantageously used. These ultr-a-high-molecular-weight ethylene/~-ole~in copolymers can be used singly or in the ~orm o~ mixtures o~ ~wo or more of them.
Preparation Process In the present invention, the ultra-high-molecular-- ~ 3 ~
weight polyethylene (A) i8 combined with -the ultra-high-molecular-weight ethylene/~-olefin copolymer (B) at a weight ratio (A)/(B) of from 10/90 to 90/10, especially from 20/80 to 80/20, so that the content of the ~-olefin having at least 3 carbon atoms is such that tho number of branched chains per 1000 carbon atoms is within the above-mentioned range.
In order to make melt-shaping o~ the ultra high-molecular-weight olefin resin possible, a diluen-t is incorporated into the composition of ~he pr0sent invention. Solvents for the ultra-high-molecular weight olefin resin composition and various waxy substances having a compatibility with the ultra-high-molecular-weight olefin resin composition are used as the diluent.
A solvent having a boiling point higher, especially by at least 20 C, than the melting point of the above-mentioned copolymer is preferably used.
As specific examples o~ the solvent, there can be mentioned aliphatic hydrocarbon solvents such as n-nonane, n-decane, n-undecane, n-dodecane, n-te-tradecane, n-octadecane, liquid paraffin and kerosene, aromatic hydrocarbon solvents such as xylene, naphthalen0 tetralin, butylbenzene, p-cymene, cyclohexylbenzene, diethylbenzene, pentylbenzene, dodecylbenzene, bicyclohexyl, decalin, methylnaphthalene and ethylnaphthalene, hydrogenated derivatives thereof, halo~enated hydrocarbon solvents such as 1,1,2,2-tetrachloroethane, pentachloroethane, hexachloroethane, 1,2,3-trichloropropane, dichlorobenzene, 1,2,4-trichlorobenzene and bromobenzene, and mineral oils such as para~fin type process oil, naphthene type process oil and aromatic process oil.
Aliphatic hydrocarbon compounds and derivatives thereo~ are ~Ised as the wax.
The aliphatic hydrocarbon compound is a so called ' ` ' ~ ' ' '' ;
13 '~ L 7 paraffin wax composed mainly of a sa-turated aliphatic hydrocarbon compound and having a molecular weight lower than 2000, preferably lower than 1000, especially pre~erably lower than 800. As specific examples o~ the aliphatic hydrocarbon compound, there can be mentioned n-alkanes having at least 22 carbon atoms, such as docosane, tricosane, tetracosane and triacontane, mixtures containing an n-alkane as mentioned above as the main component and a lower n-alkane, so-called para~rin waxes separated and puri~ied ~rom petroleum, low-pressure and medium-pressure polyole~in waxes which are low-molecular-weight polymers obtainsd by polymerizing ethylene or copolymerizing ethylane with other ~-olefin, high-pressure polyethylen0 waxes, ethylene copolymer waxes, waxes obtained by reducing the molecular weight o~ polyethylene such as medium-pressure, low-pressure or high-pressure polyethylene by thermal degradation or the like~ and oxidized waxes and maleic acid-modi~ied waxes obtained by oxidizing the ~oregoing waxes or modi~ying the ~oregolng waxes ~ith maleic acid.
As the hydrocarbon derivative, there can be mentioned ~atty acids, aliphatic alcohols, ~atty acid amldes, ~atty acid esters, aliphatic mercaptans, aliphatic aldehydes and aliphatic ketones having at least 8 carbon atoms, pre~erably 12 to 50 carbon atoms, or a molecular weight G~ 130 to 2000, pre~erably 200 to 800, which are compounds having at the terminal of an aliphatic hydrocarbon group (such as an alkyl or alkenyl group) or in the interior theraof, at least one, preferably one or two, especially pre~erably one, of ~unctional groups such as a carboxyl group, a hydroxyl group, a carbamoyl group, an ester group, a mercapto group and a carbonyl group.
As specl~ic examples, there can be mentioned ~atty `` ~ 3 ~ 7 acids such as capric acid, lauric acid, myristic acid, palmitic acid, stearic acid and oleic acid, alipha-tic alcohols such as lauryl alcohol, myristyl alcohol, cetyl alcohol and stearyl alcohol, ~atty acid amides such as caprylamide, laurylamide, palmitylamide and stearylamide, and fatty acid esters such as st0aryl acetate.
The ratio between the ultra-hlgh-molecular-weight ole~in resin composition and the diluent di~ers according to the kinds of them, but it is generally preferred that the above-ment~oned ratio is in the range, of from 3/97 to 80/20, especially from 15/85 to 60/40, If the amount o~ the diluent is too smal] and below the above-mentioned range, the melt viscosity becomes too high, and melt kneading or melt shaping becomes di~icult and such troubles as sur~ace roughening o~ the shaped body and breaking at the drawing step are o~ten caused. I~ the amount of the diluent is too large and exceeds the above-mentioned range, melt kneading is dif~icult and the drawability o~
the shaped body is poor.
It is pre~erred that melt kneading be carrled out at a temperature o~ 150 to 300 C, especially 170 to 270 C. If the temperature is too low and below the above-mentioned ranga, the melt viscosity i8 too high and melt shaping becomes difficult. I~ the temperature i9 too high and exceeds the above-mentioned range, the molecular weight of the ultra-high-molecular-welght ole~in composition is reduced by thermal degradation and a shaped body hav~ng a hlgh elastic modulus and a high strength can hardly b~ obtained. Mixing can be accomplished by dry blending using a Henschel mixer or a V-type blender or by melt mixing using a singl~-screw or multiple-screws extruder.
Melt shaping is generally accomplished according to ' 3 ~ 7 the melt extrusion shaping method. For ~xample~
filaments to be drawn can be obtained by melt extrusion through a spinneret. In this case, a melt extruded from a spinnaret may be drafted, that is, elongated in the molten state. The draft ra-tio can be defined by the following formula draft ratio = V/Vo (1~
wherein Vo stands for the extruæion speed of the molten resin in a die ori~ica and V stands for the winding speed of the cooled and solidified undrawn body.
The dra~t ratio is chang0d according to th~
temperature of the mixture, the molecular weight o~ the ultra~high-molecular-weight olefin resin composition and the like, but the draft ratio can be ordinarily adjusted to at least 3, preferably at least 6.
The so-obtained undrawn shaped body of the ultra-high-molecular-weight olefin resin composition is subjected to a drawing operation. The degree of drawing is, of course, such that a molecular orientation is effectively given in at least ona axial direction of the drawn fiber of the ultra-high-molecular-wei~ht ole~in composition.
It is generally preferred that drawing of the shaped body of the ultra-high-molecular-weight olefin resin composition be carried out at 40 to 160 C, especially 80 to 145 C. As the heating medium for heating and maintaining the undrawn shaped body at th0 above-mentioned tamperature, there can be used any of air 9 steam and liquid media. I~ the drawing operation B i9 carried out by using, as tha heating medlum, a medium capable of removing the above-mentionèd diluent~
extraction and having a boiling point higher than tha~
o~ the composition constituting the shaped body, such as decalin, decane or kerosene, removal o~ the diluent becomes possible, and drawing unevenness can be eliminated at the drawing step and a high draw ratio can be adopted. Accordingly, use o~ the above-mentioned medium is preferred.
The means ~or removing the excessive diluent from the ultra-high-molecular-weight olefin resin co~posltion is not limited to the above-mentioned method. For example, the excessive diluent can be e~rectively removed according to a method in which the undrawn shaped body is treated with a solvent such as hexane~
heptane, hot ethanol, chloro~orm or benzene and is then drawn, or a method in which the drawn shaped body is treated with a solvent such as hexane, heptane, hot ethanol, chloro~orm or benzene, whereby a drawn shaped body having a high elastic modulus and a high strength can be obtained.
The drawing operation can be per~ormed in a single stage or two or more stages. The draw ratio depends on the desired molecular orientation and the e~fect o~
~0 improving the malting temperature characteristic by the molecular orientation. In general, however, satis~actory results can be obtalned if the drawing operation is carried out so that the draw ratio is 5 to 80, especially 10 to 50.
In general, multi-staged drawing conducted in at least two stages is advantageous. Namely, it is pre~erred that at the ~irst stage, the drawing operation be carried out at a relatively low temperature of 80 to 120 C while extracting the diluent contained in the extruded shaped body and at the second and subsequent stages, drawing o~ the shaped body be carried out at a temparature of 120 to 160 C, which is higher than the drawing temperature adopted at the ~irst stage~
The uniaxial drawing operation ~or a ~ilament can be accomplished by ~tretch-drawing between rollers ~ ~ 3 ~
differing in the peripheral speed.
The so-obtained molecularly oriented shaped body can be heat-treated under restrained conditions, if desired. This heat treatment is generally carried out at a temperature o~ 140 to 180 C, especially 150 to 175 C, for 1 to 20 minutes, especially 3 to lO minutes.
By this heat treatment, crystallization o~ the oriented crys~al zone is rurther advanced, the crystal melting temperature is shi~ted to the high temperature side, and the strength and elastic modulus and the creep resistance at high temperatures are improved.
Drawn Fiber As pointed out hereinbefore, the drawn fiber of -the present inventlon is characterized in that the ~iber has at least two crystal melting endothermic peaks, close to each other, in the region of temperatures higher by at least 15 C than the crys-tal melting temperature (T~) of polyethylene determined as -the main melting endothermic peak at the second temperature elevation, when measured in the restrained state by a di~ferential scanning calorimeter. By dint o~ this speci~ic crystal structure, the ~iber of the present invention can have such surprising characteristics that when a load corresponding to 30% of the breaking load at room temperature is applied at a sample length o~ 1 cm and an ambient temperature of 70 C, the initial 010ngation arter 60 seconds ~rom the point o~ the initiation o~
application of the load is lower than 5%, especially lower than 4%, and the average creep spesd durlng the perlod o~ ~rom the point o~ 90 seconds ~rom the initiation o~ application of the load to the point o~
180 seconds ~rom the initiation o~ application o~ the load is lower than l x 10 4 sec l, e~pecially lowar than 7 x 10-5 sec~l.
Th~ inherent crystal melting temperature (Tm) o~
,.
13~8 ~ ~
the ultra-high-molecular-weight ole~in resin composition can be determined according to a method in which the shaped body is completely molten once and then cooled to moderate the molecular orientation in the shaped body and the temperature is elevated again, that is, by the second run in a so-called dirferential scanning calorimeter.
In the present inventlon, the melting point and crystal melting peak are determined according to the ~ollowing methods.
The melting point is measured by using a di~ferential scanning calorimeter (Model DSC II supplied by Perkin-Elmar) in the following manner. About 3 mg of a sample was wound on an aluminum plate having a size o~
Moreover, Japanese Patent Application Laid-Open Specification No. 187614/84 discloses a process in which a melt-kneaded mixture as mentioned above is extruded, dra~ted, cooled, solidi~ied and then drawn.
If ultra-high-molecular-weight polyethylene is shaped into a ~iber and the Piber i5 strongly drawn, the elastic modulus and tensile strength are increased with increase o~ the draw ratio~ This drawn fiber has good mechanical properties such as high elastic modulus and hlgh tensile strength and is excellent in light weight characteristic, water resistance and weatherability.
However, this drawn fibar is still insu~icient and defectlve in -that the initial elongation is large and 1 ~ ~ q~
the creep resistance is poor.
The initial elongation is a phenomenon which is peculiarly and commonly observed in organic fibers, and this phenomenon is observed even in rigid high polymers such as a Kevlar fiber (wholly aromatic polyamide fiber). Especially in the above-mentioned polyethylene fiber having high elastic modulus and high strength, the initial elongation is so large as about 1~ at normal temperature, and a high elastic modulus cannot be sufficiently utilized in the field of, for example, a composite material or the like. More specifically, influences by this large initial elongation are serious in fiber-reinforced resin composite materials, tension members (optlcal fiber cords) and the like.
Summar~ of the Invention It is therefore a primary object of the present invention to provide a polyolefin fiber which is highly improved in the initial elongation and creepdresistance ?
and has high strength and elastic modulus,&-R~ a process for the preparation of this polyolefin fiber.
More specifically, in accordance with one aspect of the present invention, there is provided a polyolefin fiber having an improved initial elongation, which comprises a strongly drawn body of a composition comprising ultra-hlgh-molecular-weight polyethylene and an ultra-high-molecular-weight copolymer of ethylene with an olefin having at least 3 carbon atoms at such a ratio that the content of the ole~in having at least 3 carbon atoms in tho entire composition is such that the number of side chains per 1000 carbon atoms in the composition is 0.2 to 5.0 on the average, and having an intrinsic viscosity ~) of at least 5 d~/g as the entire compositlon, wherein the strongly dra~n body has at least two crystal melting endothermic peaks, close to each othar, in the region o~ temperatures higher by at , :, least 15 C than the inh0rent crystal melting temperature (Tm) Or the composition determined as the main melting endothermic peak at the second temperature elevation when measured in the res-trained state by a differential scanning calorimeter.
In accordance with another aspect of the present invention, there is provided a process for the preparation of a polyolefin fiber having an improved initial elongaeion, which comprises melt-kneading a composition comprising ultra-high-molecular-weight polyethylene having an intrinsic viscosity ~ of at least 5 d~/g, and an ultra-high-molecular-weight ethylene/~-olefin copolymer having an intrinsic viscosity (~of at least 5 d~/g, said ~-olefin having at least 3 carbon atoms, and having such a content of the 6~-olefin having at least 3 carbon atoms that the number of side chains of thec~-olefin per lO00 carbon atoms in the copolymer is 0.5 to lO on the average, at a weight ratio of from lO/90 to 90/lO, in the presence of a diluent, spinning the kneaded mixture and drawing the obtainad fiber at a draw ratio of at least lO.
When a load corresponding to 30% of the breaking load at room temperature is applied to the polyolefin fiber of the present invention at a sample length of l cm and an ambient temperature of 70 C, the init~al elongation after 60 seconds from the point of the Lnitiation of the load is lower than 5% and the average - creep speed during the perlod of from the point of 90 seconds from the initiation of application of the load to the polnt of 180 seconds from the inltiation of application of the load is lower than l x 10 4 sec 1, These characteristics of the fiber of the present ~nvention are quite surprising.
Brie~ Description o~ the Drawin~s Fig. 1 ~s a graph illustrating the creep :
, characteristics o~ an ultra-high-molecular-weight polyethylene ~iber (~), an ultra-high-molecular-weight ethylene/bu-tene-l copolymer ~iber ~5) and fibers (l) through (3) of compositions of both the polymers.
Figs. 2, 3, 4, 5 and 6 are di~ferential thermal curves of the foregoing samples (l) through (5).
Detailed Description of the Pre~erred Embodimen-ts The present invention is based on the ~inding that a composition comprising ultra-high-molecular-weight polyethylene and an ultra-high-molecular-weight copolymer of ethylene with an ~-olefin having at least 3 carbon atoms (hereinaPter re~erred to as "ultra-hi~h-molecular-~eight ethylene/~-ole~in copolymer") at a certain blend ratio is e~cellent in the spinnability and drawability and can be easily shaped in a strongly drawn shaped body, and this drawn shaped body has vèry high elastic modulus and strength and also has excellent creep resistance and in this drawn shaped body,.the initial elongation is controlled to a very low level.
Ultra-high-molecular-weight polyethylene can be drawn at a high draw ratio and the fiber obtained at a high draw ratio shows high strength and high elastic modulus, but the drawn fiber is de~ective in that the creep resistance is poor. On the other hand, a ~iber o~
an ultra-high-molecular-weight ethylene/~-ole~in copolymer has an excellent creep resistance, but the drawability is not surficient and a yarn having high strength and high elastic modulus can hardly be obtained. A highly drawn ~iber comprising ultra-high-molecular-weight polyethylene and an ultra-high-molecular-weight ethylene/~-ole~in copolymer at a certain weight ratio according to the present invention has high strength and high elastic modulus o~ the former polymer and high creep resistance o~ the latter polymer synergistically and moreover, the initial elongation is .
drastically reduced in this drawn fiber. Thase characteristics are quite surprising.
Fig. 1 illustrates the relation between -the time elapsing after application of the load and the creep elongation, which is observed with respect to various highly drawn polyolefln fibers when a load correspond~ng to 30% of the breaking load at room temperature is applied at a sample length of 1 cm and an ambient temperature of 70 C. In Fig. 1, sample (4) is an ultra-high-molecular-weight polyethylene fiber, sample (5) is an ultra-high-molecular-weight ethylene/butene-1 copolymer fiber, and samples (1), (2) and t3) are fibers of compositions comprising the above-mentioned ultra-high-molecular-weight polyethylene and ultra-high-molecular-weight ethylene/butene-l copolymer at weight ratios of 10/20, 15/15 and 20/10, respectively. In short, the creep characteristics of these fibers are shown in Fig. 1. Incidentally, the respective samples are described in detail in the examples given hereinafter.
From the results shown in Fig. 1, it is seen that in the fiber of the composition of the present invention, the initial elongation (the elongation after 60 seconds from the point of the initiation o~
application of' the load) is controlled to a much lower level even under an accelerated condition of 70 C than in -the fibers composed solely o~ the respective components.
Figs. 2, 3, 4, 5 and 6 are temperature-mslting thermal curves measured by a differential ~canning calorimeter with respect to flbers (multifilaments~ of samples (1) through (5) used for the measurement of Fig.
1 in the ~tate where the sample is wound on an aluminum sheet having a thickness of 0.2 mm and the end is restrained. The crystal melting temperatures (Tm) of ~ 3 ~ 7 samples (1) through (3) according to ~he present invention, as determined as the main melting endo-thermic peak as the second temperature elevation are 135.0 C, 135.6 C and 136.2 C, respectively. Accordingly, it is 5 seen that the ~iber o~ the present invention has, in the restrained state, a crystal ~elting pea~ only in the region o~ temperatures substantially higher by at least 15 C than Tm and this peak appears as at least two peaks close to each other. This crystal melting ?
10 characteristics has a close relation to drastic reduction oP the initlal elongation.
The ~act that in the polyole~in fiber o~ the present invention, the initial elongation is controlled to a very small value by blending the two components was 15 accidentally found as a phenomenon, and the reason i9 still unknowr~. However, it is presumed that the reason will probably be as follows, though the reason described below is not binding one. In general, a drawn fiber has a structure in which the polymer chain passes through a 20 crystalline zone and an amorphous zone alternately and the crystalline zone is oriented in the drawing direction, and it is considered that it is the amorphous zone that has influences on the initial elongation o~
the ~iber. In the polyolefin fiber oP the present 25 invention, since the ~iber comprises ultra-high-molecular-weight polyethylene and an ultra-high-molecular-weight ethylene/~-olefin copolymer, a crystal structure di~erent from the crystal of polyethylene is introduced into the portion to be inherently ~ormed into 30 an amorphous zone or the length of the amorphous zone is shortened. It is considered that for this reason, the ini~ial elongation can be reduced. As pointed out hereinbefore, the results o~ the di~ferential thermal analysis o~ the polyole~in fiber o~ the present 35 invention indicate formation o~ two phases o~ crystals ' :: , ~ 3 ~ 7 differing ln the melting peak.
From the viewpoint of the mechanical propertles of ths fiber, it is important that the polyolefln composition constituting the fiber of the present invention, as a whole, should have an intrinsic viscosity of at least 5 d~/g, especially 7 to 30 de/g.
Since the molecule ends do not participate in the strength of the fiber and the number of the molecule ends is a reciprocal number of the melecular weight (viscosity), it is seen that a highor intrinsic viscosity ~ gives a higher strength.
In the present invention, it is important that the polyolefin composition should comprise the ultra-high-molecular-weight ethylene/~-olefin copolymer ln such an amount that the number of branched chains per 1000 carbon atoms in the composition is 0.2 to 5.0 on the average, especially 0.5 to 3.0 on the average. If tha number of branched chains is too small and below the above-mentioned range, it is difficult to ~orm an internal structure of the fiber effective for reducing the initial elongation and improving the creep resistance. In contrast, if the number of branched chains is too large and exceeds the above-mentioned range, the crystallinity is drastically degraded and it is difficult to obtain high elastic modulus and strength. In the present invention, determination of branched chains o~ the com~os~tion is carried out by Sf ~ C ~ O.~ c~7~ s c ~De using an infrared ~ 3~ (supplied by Nippon Bunko Xogyo). More specifically, the absorbance at 1378 cm 1 based on the deformation vibration o~ the methyl group at the end of the branch of the ~ ole~in introduced in the ethylene chain is measured and the number o~ branched methyl groups per lO00 carbon atoms can be easily obtained from the measured value with reference to a calibration curve prepared in advance by us~ng a model compound in a 13C nuclear magnetic resonance apparatus.
The present invention will now be described in detail.
Starting Materials The ultra-high-molecular-weight polyethylene used in the present invention is known, and any of known polymers can be optionally used. In order to obtain a fiber having high strength and hlgh elastic modulus, it is pre~erred that the intrinsic viscosity o~ the ultra-high-molecular-weight polyethylene be at least 5 dQ/g, especially 7 to 30 dR/g.
From the same viewpoint, the ultra-high-molecular-weight ethylene/~-olefin copolymer as the other component should also have an intrinsic viscosity ~of at least 5 dQ/g, especially 7 to 30 dR/g. What must be taken into consideration here i5 that i~ the difference of the molecular weight between the ultra-high-molecular-weight polyethylene and the ultra-high-molecular-weight ethylene/~-ole~in copolymer is too large, the creep resistance o~ the ~inal ~iber tends to decrease. Accordlngly, it is pre~erred that the di~erence o~ the intrinsic viscosity between both the resins be smaller than 5 d~/g, especially smallar than 3 dQ/g-As the olefin having at least 3 carbon atoms, therecan be used at least one member selected from mono-olefins ~uch as propylene, butene-l, pentene-1, 4-methylpentene-l, hexene-l, heptene-l and octene~l.
Furthermore, hydrocarbons having at least two unsaturated bonds in the molecule, pre~erably at least two double bonds, can b~ used. For example, there can B be mentionedbc ~n ~ ga ed diene type hydrocarbon compounds such as 1,3-~ eR~, 2 methyl-2,4-pentadiens, 2,3=
dimethyl-1,3-butadiene, 2,4-hexadiene, 3-methyl-2,4-' g hexadiene, 1,3-pentadiene and 2-methyl-1,3-bu~adiene, non conjugated diene type hydrocarbon compounds such as 1,4-pentadiene, 1,5-hexadiene t 1,6-heptadiene, 1,7-octadiene~ 2,5-dimethyl-1,5-hexadiene, 4-methyl-1,4-hexadîene, 5-methyl-1,4-hexadiene, 4-ethyl-1,4-hexadiene, 4,5-dimethyl-1,4-hexadiene, 4-methyl-1,4-h0ptadiene, 4-ethyl-1,4-heptadiene, 5-methyl-1,4-heptadiene, 4-ethyl-1,4-octadiene, 5-methyl-1,4-octadiene and 4-n-propyl-1,4-decadiene, conjugated polyolefin type hydrocarbon compounds such as 1,3,5-hexatriene, 1,3,5,7-octatetraene and 2-vinyl-1,3-butadiene, non-conjugated polyole~in type hydrocarbon compounds such as squalene, and divinylbenzene and vinylnorbornene.
The ultra-high-molecular-weight ethylee/~-olefin copolymer used in the present invention is obtained by slurry-polymerizing ethylene and an ~ole~in having at least 3 carbon atoms as the comonomer in an organic solvent by using a Ziegler type catalyst.
In this case, the amount used o~ the olefin comonomer should be such that the number of side chains (branched chains) per 1000 carbon atoms ln the ~inal composition i5 0.2 to 5, especially 0.5 to 3.
The ethylene/~-ole~in copolymer most e~ective ~or attaining the obJect o~ the present invention is an ethylene/butene-l copolymer, and an ethylene/4-methylpentene-l copolymer, an ethylene/hexene-l copolymer, an ethylene/octene-l copolymer, an ethylene/propylene copolymer, an ethylene/propylene/4-methylpentene-l copolymer and an ethylene/1,5-hexadiene copolymer are advantageously used. These ultr-a-high-molecular-weight ethylene/~-ole~in copolymers can be used singly or in the ~orm o~ mixtures o~ ~wo or more of them.
Preparation Process In the present invention, the ultra-high-molecular-- ~ 3 ~
weight polyethylene (A) i8 combined with -the ultra-high-molecular-weight ethylene/~-olefin copolymer (B) at a weight ratio (A)/(B) of from 10/90 to 90/10, especially from 20/80 to 80/20, so that the content of the ~-olefin having at least 3 carbon atoms is such that tho number of branched chains per 1000 carbon atoms is within the above-mentioned range.
In order to make melt-shaping o~ the ultra high-molecular-weight olefin resin possible, a diluen-t is incorporated into the composition of ~he pr0sent invention. Solvents for the ultra-high-molecular weight olefin resin composition and various waxy substances having a compatibility with the ultra-high-molecular-weight olefin resin composition are used as the diluent.
A solvent having a boiling point higher, especially by at least 20 C, than the melting point of the above-mentioned copolymer is preferably used.
As specific examples o~ the solvent, there can be mentioned aliphatic hydrocarbon solvents such as n-nonane, n-decane, n-undecane, n-dodecane, n-te-tradecane, n-octadecane, liquid paraffin and kerosene, aromatic hydrocarbon solvents such as xylene, naphthalen0 tetralin, butylbenzene, p-cymene, cyclohexylbenzene, diethylbenzene, pentylbenzene, dodecylbenzene, bicyclohexyl, decalin, methylnaphthalene and ethylnaphthalene, hydrogenated derivatives thereof, halo~enated hydrocarbon solvents such as 1,1,2,2-tetrachloroethane, pentachloroethane, hexachloroethane, 1,2,3-trichloropropane, dichlorobenzene, 1,2,4-trichlorobenzene and bromobenzene, and mineral oils such as para~fin type process oil, naphthene type process oil and aromatic process oil.
Aliphatic hydrocarbon compounds and derivatives thereo~ are ~Ised as the wax.
The aliphatic hydrocarbon compound is a so called ' ` ' ~ ' ' '' ;
13 '~ L 7 paraffin wax composed mainly of a sa-turated aliphatic hydrocarbon compound and having a molecular weight lower than 2000, preferably lower than 1000, especially pre~erably lower than 800. As specific examples o~ the aliphatic hydrocarbon compound, there can be mentioned n-alkanes having at least 22 carbon atoms, such as docosane, tricosane, tetracosane and triacontane, mixtures containing an n-alkane as mentioned above as the main component and a lower n-alkane, so-called para~rin waxes separated and puri~ied ~rom petroleum, low-pressure and medium-pressure polyole~in waxes which are low-molecular-weight polymers obtainsd by polymerizing ethylene or copolymerizing ethylane with other ~-olefin, high-pressure polyethylen0 waxes, ethylene copolymer waxes, waxes obtained by reducing the molecular weight o~ polyethylene such as medium-pressure, low-pressure or high-pressure polyethylene by thermal degradation or the like~ and oxidized waxes and maleic acid-modi~ied waxes obtained by oxidizing the ~oregoing waxes or modi~ying the ~oregolng waxes ~ith maleic acid.
As the hydrocarbon derivative, there can be mentioned ~atty acids, aliphatic alcohols, ~atty acid amldes, ~atty acid esters, aliphatic mercaptans, aliphatic aldehydes and aliphatic ketones having at least 8 carbon atoms, pre~erably 12 to 50 carbon atoms, or a molecular weight G~ 130 to 2000, pre~erably 200 to 800, which are compounds having at the terminal of an aliphatic hydrocarbon group (such as an alkyl or alkenyl group) or in the interior theraof, at least one, preferably one or two, especially pre~erably one, of ~unctional groups such as a carboxyl group, a hydroxyl group, a carbamoyl group, an ester group, a mercapto group and a carbonyl group.
As specl~ic examples, there can be mentioned ~atty `` ~ 3 ~ 7 acids such as capric acid, lauric acid, myristic acid, palmitic acid, stearic acid and oleic acid, alipha-tic alcohols such as lauryl alcohol, myristyl alcohol, cetyl alcohol and stearyl alcohol, ~atty acid amides such as caprylamide, laurylamide, palmitylamide and stearylamide, and fatty acid esters such as st0aryl acetate.
The ratio between the ultra-hlgh-molecular-weight ole~in resin composition and the diluent di~ers according to the kinds of them, but it is generally preferred that the above-ment~oned ratio is in the range, of from 3/97 to 80/20, especially from 15/85 to 60/40, If the amount o~ the diluent is too smal] and below the above-mentioned range, the melt viscosity becomes too high, and melt kneading or melt shaping becomes di~icult and such troubles as sur~ace roughening o~ the shaped body and breaking at the drawing step are o~ten caused. I~ the amount of the diluent is too large and exceeds the above-mentioned range, melt kneading is dif~icult and the drawability o~
the shaped body is poor.
It is pre~erred that melt kneading be carrled out at a temperature o~ 150 to 300 C, especially 170 to 270 C. If the temperature is too low and below the above-mentioned ranga, the melt viscosity i8 too high and melt shaping becomes difficult. I~ the temperature i9 too high and exceeds the above-mentioned range, the molecular weight of the ultra-high-molecular-welght ole~in composition is reduced by thermal degradation and a shaped body hav~ng a hlgh elastic modulus and a high strength can hardly b~ obtained. Mixing can be accomplished by dry blending using a Henschel mixer or a V-type blender or by melt mixing using a singl~-screw or multiple-screws extruder.
Melt shaping is generally accomplished according to ' 3 ~ 7 the melt extrusion shaping method. For ~xample~
filaments to be drawn can be obtained by melt extrusion through a spinneret. In this case, a melt extruded from a spinnaret may be drafted, that is, elongated in the molten state. The draft ra-tio can be defined by the following formula draft ratio = V/Vo (1~
wherein Vo stands for the extruæion speed of the molten resin in a die ori~ica and V stands for the winding speed of the cooled and solidified undrawn body.
The dra~t ratio is chang0d according to th~
temperature of the mixture, the molecular weight o~ the ultra~high-molecular-weight olefin resin composition and the like, but the draft ratio can be ordinarily adjusted to at least 3, preferably at least 6.
The so-obtained undrawn shaped body of the ultra-high-molecular-weight olefin resin composition is subjected to a drawing operation. The degree of drawing is, of course, such that a molecular orientation is effectively given in at least ona axial direction of the drawn fiber of the ultra-high-molecular-wei~ht ole~in composition.
It is generally preferred that drawing of the shaped body of the ultra-high-molecular-weight olefin resin composition be carried out at 40 to 160 C, especially 80 to 145 C. As the heating medium for heating and maintaining the undrawn shaped body at th0 above-mentioned tamperature, there can be used any of air 9 steam and liquid media. I~ the drawing operation B i9 carried out by using, as tha heating medlum, a medium capable of removing the above-mentionèd diluent~
extraction and having a boiling point higher than tha~
o~ the composition constituting the shaped body, such as decalin, decane or kerosene, removal o~ the diluent becomes possible, and drawing unevenness can be eliminated at the drawing step and a high draw ratio can be adopted. Accordingly, use o~ the above-mentioned medium is preferred.
The means ~or removing the excessive diluent from the ultra-high-molecular-weight olefin resin co~posltion is not limited to the above-mentioned method. For example, the excessive diluent can be e~rectively removed according to a method in which the undrawn shaped body is treated with a solvent such as hexane~
heptane, hot ethanol, chloro~orm or benzene and is then drawn, or a method in which the drawn shaped body is treated with a solvent such as hexane, heptane, hot ethanol, chloro~orm or benzene, whereby a drawn shaped body having a high elastic modulus and a high strength can be obtained.
The drawing operation can be per~ormed in a single stage or two or more stages. The draw ratio depends on the desired molecular orientation and the e~fect o~
~0 improving the malting temperature characteristic by the molecular orientation. In general, however, satis~actory results can be obtalned if the drawing operation is carried out so that the draw ratio is 5 to 80, especially 10 to 50.
In general, multi-staged drawing conducted in at least two stages is advantageous. Namely, it is pre~erred that at the ~irst stage, the drawing operation be carried out at a relatively low temperature of 80 to 120 C while extracting the diluent contained in the extruded shaped body and at the second and subsequent stages, drawing o~ the shaped body be carried out at a temparature of 120 to 160 C, which is higher than the drawing temperature adopted at the ~irst stage~
The uniaxial drawing operation ~or a ~ilament can be accomplished by ~tretch-drawing between rollers ~ ~ 3 ~
differing in the peripheral speed.
The so-obtained molecularly oriented shaped body can be heat-treated under restrained conditions, if desired. This heat treatment is generally carried out at a temperature o~ 140 to 180 C, especially 150 to 175 C, for 1 to 20 minutes, especially 3 to lO minutes.
By this heat treatment, crystallization o~ the oriented crys~al zone is rurther advanced, the crystal melting temperature is shi~ted to the high temperature side, and the strength and elastic modulus and the creep resistance at high temperatures are improved.
Drawn Fiber As pointed out hereinbefore, the drawn fiber of -the present inventlon is characterized in that the ~iber has at least two crystal melting endothermic peaks, close to each other, in the region of temperatures higher by at least 15 C than the crys-tal melting temperature (T~) of polyethylene determined as -the main melting endothermic peak at the second temperature elevation, when measured in the restrained state by a di~ferential scanning calorimeter. By dint o~ this speci~ic crystal structure, the ~iber of the present invention can have such surprising characteristics that when a load corresponding to 30% of the breaking load at room temperature is applied at a sample length o~ 1 cm and an ambient temperature of 70 C, the initial 010ngation arter 60 seconds ~rom the point o~ the initiation o~
application of the load is lower than 5%, especially lower than 4%, and the average creep spesd durlng the perlod o~ ~rom the point o~ 90 seconds ~rom the initiation o~ application of the load to the point o~
180 seconds ~rom the initiation o~ application o~ the load is lower than l x 10 4 sec l, e~pecially lowar than 7 x 10-5 sec~l.
Th~ inherent crystal melting temperature (Tm) o~
,.
13~8 ~ ~
the ultra-high-molecular-weight ole~in resin composition can be determined according to a method in which the shaped body is completely molten once and then cooled to moderate the molecular orientation in the shaped body and the temperature is elevated again, that is, by the second run in a so-called dirferential scanning calorimeter.
In the present inventlon, the melting point and crystal melting peak are determined according to the ~ollowing methods.
The melting point is measured by using a di~ferential scanning calorimeter (Model DSC II supplied by Perkin-Elmar) in the following manner. About 3 mg of a sample was wound on an aluminum plate having a size o~
4 mm x 4 mm x 0.2 mm (thickne~s) to restrain the sample in the orientation direction~ Then, the sample wound on the aluminum plate is sealed in an aluminum pan to form a measurement sample. The same aluminum plate i9 gealed in an empty aluminum pan to be placed in a re~erence holder, whereby a thermal balance is maintained. At first, the sample is maintalned at 30 C ~or about 1 minute, and then, the temperature is elevated to 250 C
at a temperature-elevating rate Or 10 C/min to complete the measurement o~ the melting point at the ~irst temperature elevation. Subsequently, the sample i9 maintained at 250 C for 10 minutes, and the temperature i9 dropped at a temperature-dropping rate o~ 20 C/min and the sample i9 malntained at 30 C for 10 minutes.
Then, the second temperature elevation is carried out by elevating the temperature to 250 C at a temperature-elevating rate o~ 10 C/min to complete the measurement o~ the melting point at the second tsmparature elevation tsecond run). The maximum value o~ the melting peak i5 designated as the meltlng point. In the case where the peak appears as a shoulder, tangential line9 are drawn .
.
~, ~ ;"~
. ~
~ 3 ~
- ~7 -on the bending point just on the low temperature side of the shoulder and on the bending point just on the high temperature side o~ the shoulder, and the point of intersection is designated as the melting point.
In the differential thermal curve of -the present invention, the endothermic peak (TH) appearing on the high temperature side is considerad to be an inherent psak o~ crystalline polyethylene segments and the endothermic peak (TL) appearing on the low temperature side is considered to be an inherent peak Or tha crystallized ethylene/~-ole~in copolymer segments. The temperatures at which TH and TL appear differ according to the mixing ratio and the orientation degree~ but these temperatur0s are generally as ~ollows.
General Ran~e~Pre~erred Range TH 150 to 157 C151 to 156 C
TL 149 to 155 C150 to 154 C
T - T 2.5 to 0.5 C2.0 to 1.0 C
Some fibers obtained by spinn~ng an ethylsne/
~-olefin copolymer and drawing the fiber at a high draw ratio show two endothermlc peaks, but in these ribers the high-temperature side peak (TH) is lower than in case o~ the riber of the present invention, and the dif~erence (TH - TL) between the two peak temperatures is larger than in the fiber of tha pressnt invention.
The ratio of the height (IH) of the peak on the high temperature side to the height (IL) of tha peak on the low temperature side in the differential thermal curve should naturally differ according to the blend ratio of both the resins, ~ut it i9 generally preferred that the IH/IL ratio be in the range of from 1.5 to 0~5 especially from 1.4 to o . 6 .
The degree o~ molecular orientation in the shaped i S3 ~ 7 ~ 18 -body can be known by the X-ray diffractometry, the bire~ringence method, the fluorescence polarizatlon method or the like. The drawn filament of the ultra-high-molecular-waight olefin resin composition according to the present invention is characterized in -that the orientakion degree by the hal~ width in the X-ray di~fractometry, described in detail, ~or example, in Yukichi Go and Kiichiro Kubo, Kogyo Kagaku Zasshi, 39, 922 (1939), that is, the orientation degree (F) deflned by the following formula:
orientation degree F = (2) wherein H stands for the half width ( ) o~ the intensity distribution curve along the Debye ring o~ the strongest paratroope plane on the equator line, is at least 0.90, preferably at least 0.95.
The drawn filament of the ultra-high-molecular-weight olefin resin composition has such a heat resistance characteristic that the strength reten-tion ratio after the heat history at 170 C for 5 minutes is 90%, especially at least 95%, and the elastic modulus retention ratio is at least 90%, especially at least 95%. This excellent heat resistance is not attained in any of conven-tional drawn polyethylene filaments.
The drawn filament o~ the ultra-high-molecular-weight olefi~ resin composition of the present inventionis sxcellent in the mechanical characteristics. Namely, the drawn ~iber of the ultra-high~molecular-weight olefin resin composition of the present invention has an elastic modulus of at least 30 GPa, especially at least 50 GPa, and a tensile strength o~ at least 1.5 GPa, `` ~3~17 especially at least 2.0 GPa.
The dra~n fiber of the present inven~ion can be used in the ~orm of a monofilament, multifilament or staple for cords, ropes, woven fabrics and non-woven ~abrics or as a reinforcer for various rubbers, resins, cements and the like.
Th~ composition compri~ing ultra-high-mol~cular-weight polyathyl0ne and an ultra-high-molecular-weight ethylene/d-ole~in copolymer according to the pr~sent invention has good spinnability and drawability and can be shaped into a highly drawn filament, and tha obtain0d fiber is axcellent in the combination o~ high strength, high elastic modulus and high creep resistanca, and furthermore, the initial elongation can be controlled to a very low level.
Accordingly, if the ~iber of the present invention is used as a stress carrier of a ~iber-reinforced composite body or other composite body, high strength and high elastic modulus of the fiber can be e~fectively utilized.
The present inventlon will now be describad in detail with re~erence to the follow.ing examples that by no means limit the scope of the invention.
Example l A mixture comprising a powder of an ultra~high-molecular-weight ethylene homopolymer (intrinsic viscosity ~ = 8.73 d~/g), a powder of an ultra-high-molecular-weight othylene/butene-l copolymer (intrinsic viscosity ~)= 9.26 dQ/g, butene~l content = 2.4 branched chains per lO00 carbon atoms) and a powder of a para~fin wax (melting point = 69 C, molecular weight =
490) was melt-spun under cond~tions describèd below.
The mixing ratio of the starting materials is shown in Table l.
Table 1 .
Sample No. Ultra-High- Ultra-High- Paraffin Molecular- Molecular- Wax (parts Weight Ethy- Weight Ethy- by ~ei~ht) len~ Homopoly- lene/Butene-l mer (parts by Copolymer we_ght) (parts by weight~
Prior to spinning, 0.1 part by weight o~ 3,5-dimethyl-tert-butyl 4-hydroxytoluene was added in an amount of 0.1 part by weight as a process stabilizer homogeneously into the mixture.
Then, the mixture was melt-kneaded a~ a set temperature of 190 C by using a screw type extruder (screw diameter = 25 mm, L/D = 25; supplied by Thermoplastic Kogyo), and subsequently, the malt was melt-spun from a spinning die having an ori~ic diamater of 2 mm, which was attached to the sxtruder. The spun fiber was taken up under drafting conditions in an alr gap having a length o~ 180 mm, and was then cool~d and solidified in air to obtain an undrawn fiber shown in Table 2.
Table 2 Sam~le No. F ness (denier) Draft Ratio Spinnability 1 593 47 good 2 643 43 good 3 643 44 good 3o The undrawn fiber was drawn under conditions describad below to obtain an oriented fibor. Namely, three-staged drawing was carried out b~ using four sets o~ godet rolls. At this drawing operation, the hsating medium in first and ~econd drawing tanks was n-decane .
3 ~ 7 and the temperatures in the first and socond tanks were 110 C and 120 C, respectively. The heating medium of a third drawing tank was trlethylene glycol, and the temperature in the third tank was 145 C. The e~ective length of each tank was 50 cm. At the drawing operation, the rotation speed of the first godet roll was set at 0.5 m/min, and a fiber having a desired draw ratio was obtained by adjusting the rotation speed of the fourth godet roll. The rotatlon speeds o~ the second and third godet rolls were approprlately arranged within such a range that drawing could be stably per~ormed. The majority of the para~fin wax mixed at the initial stage was extractad out in the n-decane tanks.
Incidentally, the draw ratio was calculated from the rotation speed ratio between ~he first and fourth godet rolls.
(Measurement of Tensile Characteristics) The elastic modulus and tensile strength were measured at room temperature (23 C) by using a tenslle tester ~Model DCS-50M supplied by Shimazu Seisakusho).
The sample length between clamps was 100 mm, and the pulling speed was 100 mm/min. The elastic modulus was calculated from the initial elastic modulus by using the gradient of the tangent. The cross-sectional area of the ~iber necessary for the calculation was determined based on the presumption that the density of the fiber was 0.960 g/cc.
(Measurement of Creep Resistance Characteristic and Initial Elongation) The creep test was carried out at a sample length of 1 cm and an ambient temperature o~ 70 C by using a thermal stress distortion measuring apparatus (Model TMA/SS10 supplied by Seiko Denshi Kogyo) under such an accelerated load condition that a load corresponding to . rO~
30% of the breaking load at room temperature was applied. In order to quantitatively evaluate the creep quantity and initial elongation, the elongation EL-60 (%) after 60 seconds ~rom the point o~ -the initiation o~
application of the load, corresponding to the ini-tial elongation be~ore entrance into the stationary creep state, and the average creep speed (sec l) during the period of ~rom the point of 90 æeconds from the initiation o~ application of the load to -the polnt of 180 seconds from the initiation of application of the load, in which the stationary creep state had already been brought about, were determined.
The tensile characteristics of the sample and the initial elongation and creep characteristics o~ tha sample are 3hown in Tables 3 and 4, respectively.
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, ~ ?3 ~ 7 o a~--~ o~ oo bO~
r\ .
~ l l l O O O
q X X X
~ c;~
W ~: ~;1) ~C
~ _ P~ ~ r- co ~ U
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O O O
~1 ~1 ~1 O O
~ Z
p::
~ ,~ ,1 ~ O
.
Z
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, 3 3 ~
As is apparent ~rom the comparison of the resul-ts obtained in the present example with the resul-ts obtained in the comparative example givsn hereina~ter, in the fiber of the present invention, the initial elongation is improved over that of the ~iber formed from the ultra-high-molecular-weight polyethylene or ultra-high-molecular-weight ethylene/butene-l copolymer alone, and the creap resistance o~ sample l is much improved over that o~ the ~iber composed solely o~ the ultra-high-molecular-weight ethylena/butan~-l copolymer~
The inherent main crystal melting temperatures (Tm) o~
the compositions o~ samples 1 through 3 were 135.0 C, 135.6 C and 136.2 C, respectively. Furthermore, the IH/IL ratios o~ samples 1 through 3 were l.lO, 1.28 and 0.73, respectively.
Comparative Example l The ultra-high-molecular-weight ethylene homopolymer and ultra-high-molecular-weight ethylene/butene-l copolymer described in Example 1 were ~ndependently melt-spun in the same manner as described in Example 1. The mixing ratios between the polymer and wax are æhown in Table 5.
Table 5 25 Sample No. Ultra-High- Ultra-High- Paraf~in Molecular- Molecular- Wax (parts Weight Ethy- Weight Ethy- b~ weight) lena Homopo- lene-Butene-l lymer (part3 Copolymer(parts by weight) by weight) The undrawn fibers obtained by spinning the mixtures shown in Table 5 are shown in Table 6.
.
~ 3 ~
Table_6 ,Sample No. Fineness(denier) Dra~t Ratio ~pinnability 4 650 40 good 892 35 good The tensile characteristics of the ~ibars obtained by drawing the undrawn fibers shown in Tabls 6 are shown in Table 7, and th~ initial elongation and creep characteristics o~ these drawn ~ib6rs are shown in Table 8.
3o ~ . . . .
~ ~3~17 g bD--`
~ U~
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~ 'o 'o e~^ C~
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V t~ N `_ o~
~3 ~ ~ oO
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~n r- ,_co O o =~ .
~I)~O ~ J
~I) rl ~I) ~1 ~: 1-l ~ Ll~
P ~1) ~ 1:13 E~ `_ ~
~0 C~
t~ ~ N
a) N
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O tD
~1 ~ L~
J~
~; Ll~
3 N ~1 .~
.
ZO
~D
~ ~ U~
tn , ,. .:
., . . : . . ` : . : `
. ' . , ~
13 ~
The inherent main crystal melting -temperatures (Tm) of the compo~itions of samples 4 and 5 are 137.5 C and 134.8 C, respectively, and the IH/IL ratio of the sample 5 was 1.45.
3o
at a temperature-elevating rate Or 10 C/min to complete the measurement o~ the melting point at the ~irst temperature elevation. Subsequently, the sample i9 maintained at 250 C for 10 minutes, and the temperature i9 dropped at a temperature-dropping rate o~ 20 C/min and the sample i9 malntained at 30 C for 10 minutes.
Then, the second temperature elevation is carried out by elevating the temperature to 250 C at a temperature-elevating rate o~ 10 C/min to complete the measurement o~ the melting point at the second tsmparature elevation tsecond run). The maximum value o~ the melting peak i5 designated as the meltlng point. In the case where the peak appears as a shoulder, tangential line9 are drawn .
.
~, ~ ;"~
. ~
~ 3 ~
- ~7 -on the bending point just on the low temperature side of the shoulder and on the bending point just on the high temperature side o~ the shoulder, and the point of intersection is designated as the melting point.
In the differential thermal curve of -the present invention, the endothermic peak (TH) appearing on the high temperature side is considerad to be an inherent psak o~ crystalline polyethylene segments and the endothermic peak (TL) appearing on the low temperature side is considered to be an inherent peak Or tha crystallized ethylene/~-ole~in copolymer segments. The temperatures at which TH and TL appear differ according to the mixing ratio and the orientation degree~ but these temperatur0s are generally as ~ollows.
General Ran~e~Pre~erred Range TH 150 to 157 C151 to 156 C
TL 149 to 155 C150 to 154 C
T - T 2.5 to 0.5 C2.0 to 1.0 C
Some fibers obtained by spinn~ng an ethylsne/
~-olefin copolymer and drawing the fiber at a high draw ratio show two endothermlc peaks, but in these ribers the high-temperature side peak (TH) is lower than in case o~ the riber of the present invention, and the dif~erence (TH - TL) between the two peak temperatures is larger than in the fiber of tha pressnt invention.
The ratio of the height (IH) of the peak on the high temperature side to the height (IL) of tha peak on the low temperature side in the differential thermal curve should naturally differ according to the blend ratio of both the resins, ~ut it i9 generally preferred that the IH/IL ratio be in the range of from 1.5 to 0~5 especially from 1.4 to o . 6 .
The degree o~ molecular orientation in the shaped i S3 ~ 7 ~ 18 -body can be known by the X-ray diffractometry, the bire~ringence method, the fluorescence polarizatlon method or the like. The drawn filament of the ultra-high-molecular-waight olefin resin composition according to the present invention is characterized in -that the orientakion degree by the hal~ width in the X-ray di~fractometry, described in detail, ~or example, in Yukichi Go and Kiichiro Kubo, Kogyo Kagaku Zasshi, 39, 922 (1939), that is, the orientation degree (F) deflned by the following formula:
orientation degree F = (2) wherein H stands for the half width ( ) o~ the intensity distribution curve along the Debye ring o~ the strongest paratroope plane on the equator line, is at least 0.90, preferably at least 0.95.
The drawn filament of the ultra-high-molecular-weight olefin resin composition has such a heat resistance characteristic that the strength reten-tion ratio after the heat history at 170 C for 5 minutes is 90%, especially at least 95%, and the elastic modulus retention ratio is at least 90%, especially at least 95%. This excellent heat resistance is not attained in any of conven-tional drawn polyethylene filaments.
The drawn filament o~ the ultra-high-molecular-weight olefi~ resin composition of the present inventionis sxcellent in the mechanical characteristics. Namely, the drawn ~iber of the ultra-high~molecular-weight olefin resin composition of the present invention has an elastic modulus of at least 30 GPa, especially at least 50 GPa, and a tensile strength o~ at least 1.5 GPa, `` ~3~17 especially at least 2.0 GPa.
The dra~n fiber of the present inven~ion can be used in the ~orm of a monofilament, multifilament or staple for cords, ropes, woven fabrics and non-woven ~abrics or as a reinforcer for various rubbers, resins, cements and the like.
Th~ composition compri~ing ultra-high-mol~cular-weight polyathyl0ne and an ultra-high-molecular-weight ethylene/d-ole~in copolymer according to the pr~sent invention has good spinnability and drawability and can be shaped into a highly drawn filament, and tha obtain0d fiber is axcellent in the combination o~ high strength, high elastic modulus and high creep resistanca, and furthermore, the initial elongation can be controlled to a very low level.
Accordingly, if the ~iber of the present invention is used as a stress carrier of a ~iber-reinforced composite body or other composite body, high strength and high elastic modulus of the fiber can be e~fectively utilized.
The present inventlon will now be describad in detail with re~erence to the follow.ing examples that by no means limit the scope of the invention.
Example l A mixture comprising a powder of an ultra~high-molecular-weight ethylene homopolymer (intrinsic viscosity ~ = 8.73 d~/g), a powder of an ultra-high-molecular-weight othylene/butene-l copolymer (intrinsic viscosity ~)= 9.26 dQ/g, butene~l content = 2.4 branched chains per lO00 carbon atoms) and a powder of a para~fin wax (melting point = 69 C, molecular weight =
490) was melt-spun under cond~tions describèd below.
The mixing ratio of the starting materials is shown in Table l.
Table 1 .
Sample No. Ultra-High- Ultra-High- Paraffin Molecular- Molecular- Wax (parts Weight Ethy- Weight Ethy- by ~ei~ht) len~ Homopoly- lene/Butene-l mer (parts by Copolymer we_ght) (parts by weight~
Prior to spinning, 0.1 part by weight o~ 3,5-dimethyl-tert-butyl 4-hydroxytoluene was added in an amount of 0.1 part by weight as a process stabilizer homogeneously into the mixture.
Then, the mixture was melt-kneaded a~ a set temperature of 190 C by using a screw type extruder (screw diameter = 25 mm, L/D = 25; supplied by Thermoplastic Kogyo), and subsequently, the malt was melt-spun from a spinning die having an ori~ic diamater of 2 mm, which was attached to the sxtruder. The spun fiber was taken up under drafting conditions in an alr gap having a length o~ 180 mm, and was then cool~d and solidified in air to obtain an undrawn fiber shown in Table 2.
Table 2 Sam~le No. F ness (denier) Draft Ratio Spinnability 1 593 47 good 2 643 43 good 3 643 44 good 3o The undrawn fiber was drawn under conditions describad below to obtain an oriented fibor. Namely, three-staged drawing was carried out b~ using four sets o~ godet rolls. At this drawing operation, the hsating medium in first and ~econd drawing tanks was n-decane .
3 ~ 7 and the temperatures in the first and socond tanks were 110 C and 120 C, respectively. The heating medium of a third drawing tank was trlethylene glycol, and the temperature in the third tank was 145 C. The e~ective length of each tank was 50 cm. At the drawing operation, the rotation speed of the first godet roll was set at 0.5 m/min, and a fiber having a desired draw ratio was obtained by adjusting the rotation speed of the fourth godet roll. The rotatlon speeds o~ the second and third godet rolls were approprlately arranged within such a range that drawing could be stably per~ormed. The majority of the para~fin wax mixed at the initial stage was extractad out in the n-decane tanks.
Incidentally, the draw ratio was calculated from the rotation speed ratio between ~he first and fourth godet rolls.
(Measurement of Tensile Characteristics) The elastic modulus and tensile strength were measured at room temperature (23 C) by using a tenslle tester ~Model DCS-50M supplied by Shimazu Seisakusho).
The sample length between clamps was 100 mm, and the pulling speed was 100 mm/min. The elastic modulus was calculated from the initial elastic modulus by using the gradient of the tangent. The cross-sectional area of the ~iber necessary for the calculation was determined based on the presumption that the density of the fiber was 0.960 g/cc.
(Measurement of Creep Resistance Characteristic and Initial Elongation) The creep test was carried out at a sample length of 1 cm and an ambient temperature o~ 70 C by using a thermal stress distortion measuring apparatus (Model TMA/SS10 supplied by Seiko Denshi Kogyo) under such an accelerated load condition that a load corresponding to . rO~
30% of the breaking load at room temperature was applied. In order to quantitatively evaluate the creep quantity and initial elongation, the elongation EL-60 (%) after 60 seconds ~rom the point o~ -the initiation o~
application of the load, corresponding to the ini-tial elongation be~ore entrance into the stationary creep state, and the average creep speed (sec l) during the period of ~rom the point of 90 æeconds from the initiation o~ application of the load to -the polnt of 180 seconds from the initiation of application of the load, in which the stationary creep state had already been brought about, were determined.
The tensile characteristics of the sample and the initial elongation and creep characteristics o~ tha sample are 3hown in Tables 3 and 4, respectively.
3o ', ' : ' . ' . ~ ;
, ~ ?3 ~ 7 o a~--~ o~ oo bO~
r\ .
~ l l l O O O
q X X X
~ c;~
W ~: ~;1) ~C
~ _ P~ ~ r- co ~ U
h--U~ ,_ ~ ~ ,~ I
P ~ C~
O O O
~1 ~1 ~1 O O
~ Z
p::
~ ,~ ,1 ~ O
.
Z
U~
, 3 3 ~
As is apparent ~rom the comparison of the resul-ts obtained in the present example with the resul-ts obtained in the comparative example givsn hereina~ter, in the fiber of the present invention, the initial elongation is improved over that of the ~iber formed from the ultra-high-molecular-weight polyethylene or ultra-high-molecular-weight ethylene/butene-l copolymer alone, and the creap resistance o~ sample l is much improved over that o~ the ~iber composed solely o~ the ultra-high-molecular-weight ethylena/butan~-l copolymer~
The inherent main crystal melting temperatures (Tm) o~
the compositions o~ samples 1 through 3 were 135.0 C, 135.6 C and 136.2 C, respectively. Furthermore, the IH/IL ratios o~ samples 1 through 3 were l.lO, 1.28 and 0.73, respectively.
Comparative Example l The ultra-high-molecular-weight ethylene homopolymer and ultra-high-molecular-weight ethylene/butene-l copolymer described in Example 1 were ~ndependently melt-spun in the same manner as described in Example 1. The mixing ratios between the polymer and wax are æhown in Table 5.
Table 5 25 Sample No. Ultra-High- Ultra-High- Paraf~in Molecular- Molecular- Wax (parts Weight Ethy- Weight Ethy- b~ weight) lena Homopo- lene-Butene-l lymer (part3 Copolymer(parts by weight) by weight) The undrawn fibers obtained by spinning the mixtures shown in Table 5 are shown in Table 6.
.
~ 3 ~
Table_6 ,Sample No. Fineness(denier) Dra~t Ratio ~pinnability 4 650 40 good 892 35 good The tensile characteristics of the ~ibars obtained by drawing the undrawn fibers shown in Tabls 6 are shown in Table 7, and th~ initial elongation and creep characteristics o~ these drawn ~ib6rs are shown in Table 8.
3o ~ . . . .
~ ~3~17 g bD--`
~ U~
o--~3 ,_ .
~ 'o 'o e~^ C~
0 ~D ~ a, . . o~ X X
V t~ N `_ o~
~3 ~ ~ oO
C~
~n r- ,_co O o =~ .
~I)~O ~ J
~I) rl ~I) ~1 ~: 1-l ~ Ll~
P ~1) ~ 1:13 E~ `_ ~
~0 C~
t~ ~ N
a) N
Z
O tD
~1 ~ L~
J~
~; Ll~
3 N ~1 .~
.
ZO
~D
~ ~ U~
tn , ,. .:
., . . : . . ` : . : `
. ' . , ~
13 ~
The inherent main crystal melting -temperatures (Tm) of the compo~itions of samples 4 and 5 are 137.5 C and 134.8 C, respectively, and the IH/IL ratio of the sample 5 was 1.45.
3o
Claims (11)
1. A strongly-drawn high-strength polyolefin fiber comprising a strongly-drawn composition which is a blend of (A) ultra-high-molecular-weight polyethylene having an intrinsic viscosity (?) of at least 5 dl/g with (B) ultra-high-molecular-weight ethylene/.alpha.-olefin copolymer having an intrinsic viscosity (?) of at least 5 dl/g and containing 0.5 to 10 .alpha.-olefin groups of at least 3 carbon atoms per 1000 carbon atoms on average, at an (A):(B) weight ratio of 10:90 to 90:10, the composition before drawing having an intrinsic viscosity (?) of at least 5 dl/g as a whole, and containing 0.2 to 5.0 .alpha.-olefin groups of at least 3 carbon atoms as side chains per 1000 carbon atoms on the average, and the drawn fiber having the following properties: (i) when measured under restraint conditions using a differential scanning calorimeter, it has at least two close crystal melting peaks at temperatures higher by at least 15°C than the inherent crystal melting temperature (Tm) of the composition determined as the main peak at the time of the second temperature elevation, (ii) an initial elongation of less than 5% when measured 60 seconds from the time of initiation of application of a load, corresponding to 30% of the breaking load applied at room temperature to a test sample 1 cm long, at ambient temperature of 70°C, (iii) an average creep rate of at least 1 x 10-4 sec-1 when measured over the period of from 90 to 180 seconds after the time of initiating the application of said load, (iv) a strength retention ratio of at least 90% when measured after a heat history at 170°C for 5 minutes, (v) an elastic modulus of at least 30 GPa at room temperature, and (vi) a tensile strength of at least 1.5GPa.
2. A polyolefin fiber as set forth in claim 1, wherein, of the at least two crystal melting endothermic peaks, the endothermic peak (TH) on the high temperature side and the endothermic peak (TL) on the low temperature side appear at temperatures satisfying the requirements of TH = 150 to 157°C, TL = 149 to 155°C and TH - TL = 2.5 to 0.5°C, and the ratio (IH/IL) of the height (IH) of the peak on the high temperature side to the height (IL) of the peak on the low temperature side is in the range of from 1.5 to 0.5.
3. A polyolefin fiber as set forth in claim 2, wherein TH
and TL appear at temperatures satisfying the requirement of TH = 151 to 156°C, TL = 150 to 154°C and TH - TL = 2.0 to 1.0°C, and the ratio IH/IL is in the range of from 1.4 to 0.6.
and TL appear at temperatures satisfying the requirement of TH = 151 to 156°C, TL = 150 to 154°C and TH - TL = 2.0 to 1.0°C, and the ratio IH/IL is in the range of from 1.4 to 0.6.
4. A polyolefin fiber as set forth in claim 1, wherein the composition of (A) and (B) has an intrinsic viscosity of from 7 to 30 dl/g and from 0.5 to 3.0, on average, of .alpha.-olefin groups of at least 3 carbon atoms as side chains per 1000 carbon atoms, and wherein the difference in the intrinsic viscosity between polyethylene (A) and copolymer (B) is less than 3 dl/g.
5. A polyolefin fiber as set forth in claim 1, which has been drawn to a draw ratio of 10 to 50.
6. A polyolefin fiber as set forth in claim 1, wherein the .alpha.-olefin in the ultra-high-molecular-weight ethylene/.alpha.-olefin copolymer has at least two double bonds.
7. A polyolefin fiber as set forth in claim 6, wherein the .alpha.-olefin is a non-conjugated diene hydrocarbon.
8. A polyolefin fiber as set forth in claim 1, wherein the ultra-high-molecular-weight ethylene/.alpha.-olefin copolymer is ethylene/butene-1 copolymer.
9. An article composed of a resin or rubber reinforced with the polyolefin fiber as set forth in any one of claims 1 to 8.
10. A process for the preparation of a polyolefin fiber as defined in claim 1, which comprises melt-kneading a composition comprising ultra-high-molecular-weight polyethylene having an intrinsic viscosity (?) of at least 5 dl/g, and an ultra-high-molecular-weight ethylene/.alpha.-olefin copolymer having an intrinsic viscosity (?) of at least 5 dl/gr the .alpha.-olefin having at least 3 carbon atoms, and having such a content of the .alpha.-olefin having at least 3 carbon atoms that the number of side chains of the .alpha.-olefin per 1000 carbon atoms in the copolymer is 0.5 to 10 on average, at a weight ratio of from 10/90 to 90/10, in the presence of a diluent, spinning the kneaded mixture and drawing the obtained fiber at a draw ratio of at least 10.
11. A process according to claim 10, wherein the diluent is a wax and the ultra-high-molecular-weight olefin resin composition and the wax are used at a weight ratio of from 15/85 to 60/40.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62304484A JPH089804B2 (en) | 1987-12-03 | 1987-12-03 | Polyolefin fiber with improved initial elongation and method for producing the same |
| JP304484/87 | 1987-12-03 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1309817C true CA1309817C (en) | 1992-11-10 |
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ID=17933587
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000584905A Expired - Fee Related CA1309817C (en) | 1987-12-03 | 1988-12-02 | Polyolefin fiber having improved initial elongation and process for preparation thereof |
Country Status (8)
| Country | Link |
|---|---|
| US (2) | US5015525A (en) |
| EP (1) | EP0320188B1 (en) |
| JP (1) | JPH089804B2 (en) |
| KR (1) | KR910004698B1 (en) |
| CN (1) | CN1028547C (en) |
| AT (1) | ATE118826T1 (en) |
| CA (1) | CA1309817C (en) |
| DE (1) | DE3853140T2 (en) |
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| EP0205960B1 (en) * | 1985-06-17 | 1990-10-24 | AlliedSignal Inc. | Very low creep, ultra high moduls, low shrink, high tenacity polyolefin fiber having good strength retention at high temperatures and method to produce such fiber |
| JP3206204B2 (en) * | 1992-05-22 | 2001-09-10 | 株式会社デンソー | Throttle position sensor |
| US8563623B2 (en) * | 1996-02-13 | 2013-10-22 | The General Hospital Corporation | Radiation melt treated ultra high molecular weight polyethylene prosthetic devices |
| US8865788B2 (en) * | 1996-02-13 | 2014-10-21 | The General Hospital Corporation | Radiation and melt treated ultra high molecular weight polyethylene prosthetic devices |
| AU3953999A (en) * | 1998-06-04 | 1999-12-20 | Dsm N.V. | High-strength polyethylene fiber and process for producing the same |
| US6680265B1 (en) | 1999-02-22 | 2004-01-20 | Kimberly-Clark Worldwide, Inc. | Laminates of elastomeric and non-elastomeric polyolefin blend materials |
| ES2220899T3 (en) | 1999-08-11 | 2004-12-16 | Toyo Boseki Kabushiki Kaisha | A PROTECTIVE GLOVE THAT INCLUDES HIGH RESISTANCE POLYETHYLENE FIBERS. |
| DE19942611C1 (en) * | 1999-08-31 | 2001-07-05 | Ethicon Gmbh | Reinforced flat implant |
| US7344668B2 (en) | 2003-10-31 | 2008-03-18 | Honeywell International Inc. | Process for drawing gel-spun polyethylene yarns |
| ES2375278T3 (en) * | 2004-01-01 | 2012-02-28 | Dsm Ip Assets B.V. | PROCEDURE TO PRODUCE HIGH PERFORMANCE POLYETHYLENE MULTIFILAMENT THREAD. |
| US7846363B2 (en) | 2006-08-23 | 2010-12-07 | Honeywell International Inc. | Process for the preparation of UHMW multi-filament poly(alpha-olefin) yarns |
| US20090163679A1 (en) * | 2007-12-19 | 2009-06-25 | Braskem S.A. | Suspension polymerization process for manufacturing ultra high molecular weight polyethylene, a multimodal ultra high molecular weight polyethylene homopolymeric or copolymeric composition, a ultra high molecular weight polyethylene, and their uses |
| CN102770590B (en) * | 2009-12-23 | 2015-04-29 | 英威达技术有限公司 | Preparation method of fabric including polylefin elastic fiber |
| NL2005455C2 (en) * | 2010-10-05 | 2012-04-06 | Polymer Res & Dev | Process for producing high-performance polymer fibers. |
| CN102002769B (en) * | 2010-11-08 | 2012-12-12 | 宁波大成新材料股份有限公司 | Preparation method of ultra-high molecular weight polyethylene fiber |
| EP2697414B1 (en) * | 2011-04-13 | 2017-09-06 | DSM IP Assets B.V. | Creep-optimized uhmwpe fiber |
| CN106133215B (en) * | 2014-03-28 | 2020-10-23 | 东洋纺株式会社 | Multifilament and braid |
| EP3133191B1 (en) * | 2014-03-28 | 2021-06-02 | Toyobo Co., Ltd. | Multifilament and braid |
| US10626531B2 (en) | 2015-02-20 | 2020-04-21 | Toyobo Co., Ltd. | Multifilament and braid using same |
| EP3739088A1 (en) * | 2015-12-15 | 2020-11-18 | DSM IP Assets B.V. | Low creep fiber |
| CN111210723B (en) * | 2020-01-13 | 2022-06-03 | 京东方科技集团股份有限公司 | Flexible display assembly, rollable display device and preparation method thereof |
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| JPS5551814A (en) * | 1978-10-04 | 1980-04-15 | Mitsui Petrochem Ind Ltd | Production of drawn filament yarn having uneven surface |
| NL177759B (en) * | 1979-06-27 | 1985-06-17 | Stamicarbon | METHOD OF MANUFACTURING A POLYTHYTHREAD, AND POLYTHYTHREAD THEREFORE OBTAINED |
| JPS5841908A (en) * | 1981-09-04 | 1983-03-11 | Showa Denko Kk | Production of high-strength monofilament |
| NL8104728A (en) * | 1981-10-17 | 1983-05-16 | Stamicarbon | METHOD FOR MANUFACTURING POLYETHENE FILAMENTS WITH GREAT TENSILE STRENGTH |
| US4455273A (en) * | 1982-09-30 | 1984-06-19 | Allied Corporation | Producing modified high performance polyolefin fiber |
| JPS5982406A (en) * | 1982-10-28 | 1984-05-12 | Nippon Petrochem Co Ltd | Polyolefin yarn |
| DE3363610D1 (en) * | 1982-12-28 | 1986-06-26 | Mitsui Petrochemical Ind | Process for producing stretched articles of ultrahigh-molecular-weight polyethylene |
| JPS59130313A (en) * | 1982-12-28 | 1984-07-26 | Mitsui Petrochem Ind Ltd | Manufacture of drawn ultra-high-molecular-weight polyethylene |
| JPS59187614A (en) * | 1983-04-07 | 1984-10-24 | Mitsui Petrochem Ind Ltd | Drawn polyethylene material having ultrahigh molecular weight |
| US4737402A (en) * | 1985-02-28 | 1988-04-12 | Allied Corporation | Complex composite article having improved impact resistance |
| JPS6241341A (en) * | 1985-08-08 | 1987-02-23 | 東洋紡績株式会社 | High speed stretching of gel fiber |
| US4769433A (en) * | 1985-11-25 | 1988-09-06 | E. I. Du Pont De Nemours And Company | High strength polyolefins |
| JPH0794565B2 (en) * | 1987-08-04 | 1995-10-11 | 東洋紡績株式会社 | Creep-resistant high-strength polyethylene molding and method for producing the same |
| IN170335B (en) * | 1986-10-31 | 1992-03-14 | Dyneema Vof | |
| EP0290141B1 (en) * | 1987-05-06 | 1994-08-03 | Mitsui Petrochemical Industries, Ltd. | Molecularly oriented molded body of ultra-high-molecular-weight ethylene/alpha-olefin copolymer |
| US4842922A (en) * | 1987-10-27 | 1989-06-27 | The Dow Chemical Company | Polyethylene fibers and spunbonded fabric or web |
-
1987
- 1987-12-03 JP JP62304484A patent/JPH089804B2/en not_active Expired - Lifetime
-
1988
- 1988-12-02 US US07/279,084 patent/US5015525A/en not_active Expired - Lifetime
- 1988-12-02 CA CA000584905A patent/CA1309817C/en not_active Expired - Fee Related
- 1988-12-03 KR KR1019880016099A patent/KR910004698B1/en not_active IP Right Cessation
- 1988-12-03 CN CN88108372A patent/CN1028547C/en not_active Expired - Fee Related
- 1988-12-05 EP EP88311495A patent/EP0320188B1/en not_active Expired - Lifetime
- 1988-12-05 DE DE3853140T patent/DE3853140T2/en not_active Expired - Fee Related
- 1988-12-05 AT AT88311495T patent/ATE118826T1/en not_active IP Right Cessation
-
1991
- 1991-03-11 US US07/668,138 patent/US5143977A/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| CN1034591A (en) | 1989-08-09 |
| EP0320188A3 (en) | 1990-03-21 |
| EP0320188B1 (en) | 1995-02-22 |
| DE3853140T2 (en) | 1995-06-29 |
| EP0320188A2 (en) | 1989-06-14 |
| ATE118826T1 (en) | 1995-03-15 |
| JPH01148807A (en) | 1989-06-12 |
| KR910004698B1 (en) | 1991-07-10 |
| JPH089804B2 (en) | 1996-01-31 |
| US5143977A (en) | 1992-09-01 |
| DE3853140D1 (en) | 1995-03-30 |
| KR890010295A (en) | 1989-08-08 |
| CN1028547C (en) | 1995-05-24 |
| US5015525A (en) | 1991-05-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |