EP0924322A1

EP0924322A1 - Conjugate fibers and non-woven fabrics therefrom

Info

Publication number: EP0924322A1
Application number: EP98124236A
Authority: EP
Inventors: Hirosi Mitsui Chemicals Inc. Ishii; Kunihiko Mitsui Chemicals Inc. Takesue
Original assignee: Mitsui Chemicals Inc
Current assignee: Mitsui Chemicals Inc
Priority date: 1997-12-19
Filing date: 1998-12-17
Publication date: 1999-06-23
Also published as: KR19990063239A; CN1222588A; CN1287031C

Abstract

Conjugate fibers which are easy to make into fibers of small denier and soft, have a good feel and adequate strength and consequently are suitable for use as the material for various applications and non-woven fabrics comprising the said conjugate fibers.

The conjugate fibers at least a part of which comprise a propylene polymer having a molecular weight distribution (Mw/Mn) of 1.5 to 3.5, and non-woven fabrics made thereof. The propylene polymer may, preferably, be a polymer obtained by a single site catalyst.

The conjugate fibers may have a core-sheath structure containing core parts comprising the propylene polymer and sheaths comprising an ethylene polymer, or have a side-by-side structure containing the fiber part comprising the propylene polymer and the fiber part comprising an ethylene polymer.

Description

TECHNICAL FIELD

The present invention relates to conjugate fibers and non-woven fabrics made therefrom, specifically conjugate fibers being soft and having a good feel and adequate strength and conjugate fibers thereof. The present invention is also concerned with non-woven fabrics which are useful for use as medical and sanitary materials such as disposable diapers and industrial materials such as packaging materials.

BACKGROUND

It is known that non-woven fabrics made of polyethylene fibers are soft and have a good feel (Japanese Laid-open Patent Publication SHO 60-209010). However, polyethylene fibers are difficult to spin and hard to make into fibers of small denier. Besides, polyethylene has such properties that it tends to melt in the process of heating and pressing by use of calendering rolls and to cling to the rolls due to the low strength of the fibers. As a measure to prevent such trouble, the heating and pressing temperatures are lowered. However, in such case, it becomes difficult to achieve an adequate heat bonding of fibers due to such low temperatures, causing the problem of the fastness to rubbing of the resultant non-woven fabrics becoming inadequate.
Further, non-woven fabrics made of polypropylene fibers are also known, and they are used for sanitary and industrial materials and sundries for daily use. However, polypropylene fibers have such properties that in the spinning process, the temperature range is narrow and the spinning operation shows poor stability and that due to the inadequate heat sealability of the resultant fibers, the heat bonding of the fibers becomes unsatisfactory.
To solve this problem of heat bonding of the fibers, an attempt is made to improve the properties of the polymer on one hand, and on the other hand, sheaths are proposed for conjugate fibers of a core-sheath structure using different resins. For example, non-woven fabrics using polyethylene for the sheaths and polypropylene, polyester, etc. for the core are disclosed in Japanese Patent Publication SHO 55-483, Japanese Laid-open Patent Publication HEI 2-182960 and Japanese Laid-open Patent Publication HEI 5-263353.
However, the conventional conjugate fibers are prone to break, difficult to spin and to make into fibers of small denier, and are inferior in softness. Because of this, in order to obtain attain flexibility, an attempt has been made to increase the composition ratio of the ethylene polymer to the resin used for the fibers. However, in such case, there was the problem of being unable to achieve adequate strength.
On the other hand, various attempts have been made to improve the properties of the polymer. For example, a non-woven fabric made of a polypropylene manufactured by use of a metallocene catalyst has been proposed (for example, Japanese Laid-open Patent Publication HEI 4125).
However, the fibers and conjugate fibers that have been known in the past have been unsuccessful in meeting the conditions that the materials for the non-woven fabrics usable for various applications are required to satisfy, namely, being easy to make into fibers of small denier and soft and having a good feel and adequate strength.
Against this background, the inventors of the present invention aimed at developing conjugate fibers which are easy to make into fibers of small denier and soft, have a good feel and adequate strength and consequently are suitable for use as the material for various applications. As a result, they successfully produced the present invention.

SUMMARY

The present invention provides conjugate fibers which are easy to make into fibers of small denier and soft, have a good feel and adequate strength and consequently are suitable for use as the material for various applications. The present invention also provides non-woven fabrics which comprise the aforementioned conjugate fibers. The said non-woven fabrics, being composed of the aforementioned conjugate fibers, are soft, have a good feel and adequate strength and show such properties that because of the aforementioned conjugate fibers having adequate heat bonding properties, the resultant non-woven fabrics have excellent fastness to rubbing. For this reason, these non-woven fabrics are suitable for use as medical and sanitary materials such as disposable diapers and industrial materials such as packaging materials.
The present invention provides the conjugate fibers at least a part of which comprise a propylene polymer having a molecular weight distribution (Mw/Mn) of 1.5 to 3.5 as the aforementioned conjugate fibers, and non-woven fabrics made thereof. More preferably, the present invention provides the conjugate fibers at least a part of which comprise a propylene polymer having been obtained by use of a single site catalyst and having a molecular weight distribution (Mw/Mn) of 1.5 to 3.5 as the aforementioned conjugate fibers, and non-woven fabrics made thereof.
It should be added to help understand the present invention, that the aforementioned propylene polymer having been obtained by use of a single site catalyst and having a molecular weight distribution (Mw/Mn) of 1.5 to 3.5 is suitable for use as the material for the core parts of the conjugate fibers of a core-sheath structure, and moreover provides very good conjugate fibers of a core-sheath structure when combined with a sheath made of an ethylene polymer .
Given below is a detailed description of the conjugate fibers and non-woven fabrics of the present invention.

DETAILED DESCRIPTION

The conjugate fibers of the present invention are conjugate fibers at least part of the structure of which is composed of a propylene polymer . The fibers of the present invention may be the fibers the whole of which is composed of a propylene polymer or only part of which is composed of a propylene polymer . Examples of these conjugate fibers include various conjugate fibers of core-sheath, sandwich, side-by-side, sea island and other types, at least part of the structure of which is composed of a propylene polymer .
In the present invention, particularly the conjugate fibers of a core-sheath type comprising the core made of a propylene polymer and the sheath made of another resin and the conjugate fibers of a side-by-side type comprising a monofilament formed by the fiber part made of a propylene polymer being arranged in parallel with or being entangled with the fiber part made of another resin are preferable as they meet both of the requirements for softness and strength.
As the aforementioned other resin, ethylene polymer s may be cited as preferable examples.
Following is a detailed description of the propylene polymers used in the present invention.

Propylene polymers :

The propylene polymers used in the present invention are polymers containing not less than 90 mol%, preferably not less than 95 mol%, of a structural unit deriving from propylene, such as propylene homopolymer and random copolymer or block copolymer of propylene and another olefin, for example.
As an example of another olefin, α-olefins having 2 to 20 carbon atoms, other than propylene, and cyclic olefins having 5 to 20 carbon atoms may be cited. Specific examples of the α-olefins having 2 to 20 carbon atoms include ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and 1-eicosane. Out of them, α-olefins having 2 to 8 carbon atoms are preferable. Specific examples of cyclic olefins having 5 to 20 carbon atoms include cyclopentene, cycloheptene, norbornene, 5-methyl-2-norbornene, tetracyclo-dodecene, 2-methyl-1,4,5,8-dimethano-1,2,3,4,4a,5,5,8,8a-octahydronaphthalene, styrene and vinyl cyclohexane. Moreover, dienes such as butadiene and isoprene may be included in those examples. In the present invention, the propylene polymer may contain one or not less than two of the structural unit deriving from these examples of another olefin. Out of the examples of another olefin, α-olefins may be cited as particularly preferable examples.
In the present invention, as the propylene polymer , the aforementioned propylene homopolymer, random copolymer and block copolymer may be used singly or in combination with not less than two of them.
Out of these, random copolymers of propylene and a small amount of ethylene which contain 1 to 5.0 mol%, preferably 0.2 to 4.0 mol%, more preferably 0.5 to 3.0 mol%, of the structural unit deriving from ethylene are preferable as these random copolymers provide those non-woven fabrics which exhibit good spinnability, excellent productivity and satisfactory softness.
In the present invention, good spinnability means that there will be no breakage of filament nor fusion of the filament occurring during the processes of the extrusion of the filament from the spinneret and the stretching of the filament.
Further, the melt flow rate (MFR) of the propylene polymer of the present invention may preferably be 20 to 100 g/10min., more preferably be 25 to 100 g/10min., further preferably be 50 to 70 g/10min. The MFR of propylene polymer is measured at 230°C under a load of 2.16 kg in accordance with ASTM D1238.
Furthermore, the ratio Mw/Mn of the weight average molecular weight (Mw) to the number average molecular weight of the propylene polymer of the present invention is 1.5 to 3.5, preferably 1.7 to 2.5, from a viewpoint of spinnability and the fiber strength of conjugate fibers.
In the present invention, Mw/Mn can be determined by the normal method using GPC (gel permeation chromatography).
As a good example of the preferable method for manufacturing this propylene polymer, the polymerization method using a single-site catalyst may be cited. A propylene polymer showing a preferable molecular weight distribution and a uniform composition can be obtained by using a single-site catalyst. A single-site catalyst refers to a catalyst having a uniform active site. Various catalysts may be selected as a single-site catalyst. A known single-site catalyst already may be selected, or a single-site catalyst may be synthesized that suits the purpose of the present invention.
Examples of the single site catalysts may include a catalyst comprising
(A) a metallocene-type transition metal compound represented by the following formula(I):
(B) at least one compound activating said metallocene-type transition metal compound (A) selected from
(B-1) an organoaluminum compound
(B-2) an organoaluminum oxy compound and
(B-3) a compound which reacts with said metallocene-type transition metal compound (A) to form an ionic pair
In the above formula (I)representing said metallocene-type transition metal compound, M¹ stands for a transition metal atom in the Group IV to VIB of the periodic table, and specific examples of M¹ include zirconium, titanium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum or tungsten, preferably zirconium, titanium or hafnium in view of high activity.
R¹, R², R³ and R⁴, which may be the same oR6ifferent from one another, stand for a hydrocarbon group having 1 to 20 carbon atoms, a halogenated hydrocarbon group having 1 to 20 carbon atoms, a silicon-containing group, an oxygen-containing group, a sulfur-containing group, a nitrogen-containing group, phosphorus-containing group, hydrogen atom or halogen atom, and parts of the mutually adjacent ones out of the groups represented by R¹, R², R³ and R⁴ may be bonded to form a ring together with the hydrocarbon atoms bonded by these groups. Further, R¹, R², R³ and R⁴, which are shown in two locations, respectively, R¹ and R¹, for example, may the same oR6ifferent groups. Those groups represented by R which have the same suffix can make combinations when connected to one another to form a ring.
Specific examples of the hydrocarbon group having 1 to 20 carbon atoms may include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, hexyl group, octyl group, nonyl group, dodecyl group and eicosyl group; cycloalkyl groups such as cyclopentyl group, cyclohexyl group norbornyl group and adamantyl group; alkenyl groups such as vinyl group, propenyl group and cyclohexyl group; aryl alky groups such as benzyl group, phenylethyl group and phenylpropyl group; aryl groups such as phenyl group, tolyl group, dimethylphenyl group, trimethylphenyl group, ethylphenyl group, propylphenyl group, biphenyl group, naphthyl group, methylnaphthyl group, anthracenyl group and phenanthryl group.
Examples of the rings formed by the bonding of these hydrocarbon groups include condensed ring groups such as the benzene ring, naphthalene ring, acenaphthalene ring and indene ring and substituted condensed ring groups which the hydrogen atom on said condensed ring groups is substituted by an alkyl group such as methyl, ethyl, propyl, tert-butyl, sec-butyl and iso-butyl.
Examples of the halogenated hydrocarbon group include the group obtained by substituting the aforementioned hydrocarbon group by halogen.
Examples of the silicon-containing group include mono-hydrocarbon-substituted silyl such as methyl silyl and phenyl silyl; di-hydrocarbon-substituted silyl such as dimethyl silyl and diphenyl silyl; tri-hydrocarbon-substituted silyl such as trimethyl silyl , triethyl silyl , tripropyl silyl, tricyclohexyl silyl, triphenyl silyl, dimethylphenyl silyl, methyldiphenyl silyl, tritolyl silyl and trinaphthyl silyl; silyl ethers of mono-hydrocarbon-substituted silyl such as trimethyl silyl ether; silicon-substituted alkyl groups such as trimethylsilylmethyl group; and silicon-substituted aryl groups such as trimethyl phenyl group.
In addition, examples of the silicon-containing besides the aforementioned groups include a group represented by the following formula: -SiR³ (wherein R is halogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms).
In the formula, examples of the halogen include chlorine etc. Examples of the alkyl group having 1 to 10 carbon atoms include methyl, ethyl and propyl. Examples of the aryl group having 6 to 10 carbon atoms include benzyl and methyl benzyl.
Examples of the oxygen-containing group include hydroxy group; alkoxy groups such as methoxy, ethoxy, propoxy and butoxy; aryloxy group such as phenoxy, methylphenoxy, dimethylphenoxy and naphthoxy; arylalkoxy group such as phenylmethoxy and phenylethoxy.
In addition, examples of oxygen-containing group include a group represented by the following formula: -OSiR₃ (wherein R is halogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms).
In the formula, examples of the halogen atom, the alkyl group and aryl group are same as those exemplified for the aforementioned silicon-containing group.
Examples of the sulfur-containing group include a substituted group obtained by substituting the oxygen of the aforementioned oxygen-containing group by sulfur.
In addition, examples of the sulfur-containing group besides the aforementioned groups include a group represented by the following formula: -SR (wherein R is halogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms)
In the formula, examples of the halogen atom, the alkyl group and aryl group are same as those exemplified for the aforementioned silicon-containing group.
Examples of the nitrogen-containing group include amino group; alkyl amino groups such as methyl amino, dimethyl amino, diethyl amino, dipropyl amino, dibutyl amino and dicyclohexyl amino; aryl amino or alkyl aryl amino group such as phenyl amino, diphenyl amino, ditolyl amino, dinaphthyl amino and methylpenyl amino.
In addition, examples of the nitrogen-containing group besides the aforementioned groups include a group represented by the following formula: -NR₂ (wherein R is halogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms).
In the formula, examples of the halogen atom, the alkyl group and aryl group are same as those exemplified for the aforementioned silicon-containing group.
Example of the phosphorus-containing group include a phosphino group such as dimethylphosphino and diphenylphosphino.
In addition, examples of the phosphorus-containing group besides the aforementioned groups include a group represented by the following formula: -PR₂ (wherein R is halogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms)
In the formula, examples of the halogen atom, the alkyl group and aryl group are same as those exemplified for the aforementioned silicon-containing group.
Examples of halogen represented by R¹, R², R³ and R⁴ in the formula (I) include fluorine, chlorine, bromine and iodine.
R¹, R², R³ and R⁴ in the formula (I) are preferably hydrocarbon groups, especially preferably hydrocarbon groups having 1 to 4 carbon atoms such as methyl, ethyl, propyl and butyl, a benzene ring formed by the bonding of hydrocarbon groups, and those groups having the benzene ring which the hydrogen atom on said benzene ring formed by the bonding of hydrocarbon groups is substituted by an alkyl group such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl and tert-butyl.
X¹ and X² may be the same oR6ifferent and stand for a hydrocarbon group, a halogenated hydrocarbon group, an oxygen-containing group, a sulfur-containing group, a silicon-containing group, hydrogen atom or halogen atom.
The hydrocarbon groups are preferably hydrocarbon groups having 1 to 20 carbon atoms, and its specific examples include the same groups as R¹, R², R³ and R⁴.
The halogenated hydrocarbon group are preferably a halogenated hydrocarbon group having 1 to 20 carbon atoms, and specific examples include the same groups as R¹, R², R³ and R⁴.
As examples of the oxygen-containing group and halogen atom, the same groups or atoms as R¹, R², R³ and R⁴ can be cited.
Examples of the sulfur-containing group include the same groups as R¹, R², R³ and R⁴ and sulfonate groups such as methyl sulfonate, trifluoromethanesulfonate, phenyl sulfonate, benzyl sulfonate, p-toluene sulfonate, trimethylbenzene sulfonate, triisobutylbenzene sulfonate, p-chloro benzene sulfonate and pentafluorobenzene sulfonate; sulfinate groups such as methyl sulfinate, phenyl sulfinate, benzene sulfinate, p-toluene sulfinate, trimethylbenzene sulfinate and pentafluorobenzene sulfinate.
Examples of the silicon-containing group include the same silicon-substituted alkyl group and silicon-substituted aryl group as exemplified for R¹, R², R³ and R⁴ above.
Among them, X¹ and X² are preferably halogen atom, a hydrocarbon group having 1 to 20 carbon atoms or a sulphonate group.
Y¹ in the formula (I) stands for a bivalent hydrocarbon group, a bivalent halogenated hydrocarbon group, a bivalent silicon-containing group, a bivalent germanium-containing group, a bivalent tin-containing group, -O-, -CO-, -S-, -SO-, -SO₂-, -Ge-, -Sn-, -NR⁵-, -P(R⁵)-, -P(O)(R⁵)-, -BR⁵-or-AlR⁵-. Wherein, R5 may be the same oR6ifferent from one another and stands for hydrogen atom, halogen atom, a hydrocarbon group, a halogenated hydrocarbon group or an alkoxy group. Example of the halogen atom includes chlorine. Examples of the hydrocarbon group include methyl group, ethyl group and propyl group. Examples of the halogenated hydrocarbon group include mono-chloro methyl and di-chloro ethyl.Examples of the alkoxy group include methoxy group and ethoxy group.
The hydrocarbon group as Y₁ is preferably a bivalent hydrocarbon group having 1 to 20 carbon atoms.
Specific examples of the hydrocarbon group include alkylene groups such as methylene group, dimethymethyllene group, 1,2-ethylene group, dimethyl-1,2-ethylene group , 1,3-trimethylene group , 1,4-tetramethylene group, 1,2-cyclohexylene group and 1,4-cyclohexylene group; aryllakylene groups such as diphenylmethylene group and diphenyl-1,2-ethylene group.
The halogenated hydrocarbon group is preferably a bivalent halogenated hydrocarbon group having 1 to 20 carbon atoms, and specific examples of the halogenated hydrocarbon group include a group obtained by halogenating the aforementioned bivalent hydrocarbon group having 1 to 20 carbon atoms, such as chloromethylene.
Examples of the bivalent silicon-containing group include alkyl silylene group such as silylene , methylsilylene , dimethylsilylene , diethylsilylene, di(n-propyl)silylene, di(i-propyl)silylene , di(cyclohexyl)silylene, methylphenylsilylene , diphenysilylene , di(p-tolyl)silylene and di(p-chlorophenyl)silylene ; alkylaryl silylene group; aryl silylene ; alkyl disilyl group such as tetramethyl-1,2-disilyl and tetraphenyl-1,2-disilyl ; alkyl aryl disilyl group; and aryl disilyl group.
Examples of the bivalent germanium-containing group include a group obtained by substituting the silicon of the aforementioned bivalent silicon-containing group by germanium.
Furthermore, substituted silylene groups such as a dimehylsilylene group, a diphenylsilylene group and methylphenylsilylene group are especially preferable as the bivalent silicon-containing group, bivalent germanium-containing group and bivalent tin-containing group.
Specific examples of the meso form of these transition metal compounds represented by the aforementioned formula (I) include the meso form of the following compounds:
rac-dimethylsilylenebis(2,3,5-trimethylcyclopentadienyl) zirconium dichloride,
rac-dimethylsilylenebis(2,4-dimethylcyclopentadienyl) zirconium dichloride,
rac-dimethylsilylenebis(2-methyl-4-tert-butylcyclopentadienyl) zirconium dichloride,
isopropylidene-(4-methylcyclopentadienyl)(3-methylindenyl) zirconium dichloride,
isopropylidene-(4-tert-butylcyclopentadienyl)(3-methylindenyl) zirconium dichloride,
isopropylidene-(4-tert-butylcyclopentadienyl)(3-tert-butylindenyl) zirconium dichloride,
dimethylsilylene-(4-methylcyclopentadienyl) (3-methylindenyl) zirconium dichloride,
dimethylsilylene-(4-tert-butylcyclopentadienyl) (3-methylindenyl) zirconium dichloride,
dimethylsilylene-(4-tert-butylcyclopentadienyl) (3-tert-butylindenyl) zirconium dichloride,
dimethylsilylene-(3-tert-butylcyclopentadienyl) (fuluorenyl) zirconium dichloride,
isopropylidene-(3-tert-butylcyclopentadienyl) (fuluorenyl) zirconium dichloride,
rac-dimethylsilylenebis{1-(2-methylindenyl)}zirconium dichloride,
rac-dimethylsilylenebis{1-(2-methyl-4-phenylindenyl)}zirconium dichloride,
rac-dimethylsilylenebis{1-(2-methyl-4-(α-naphthyl)indenyl)}zirconium dichloride,
rac-dimethylsilylenebis{1-(2-methyl-4-(1-anthracenyl)indenyl)}zirconium dichloride,
rac-dimethylsilylenebis{1-(2-methyl-4-(9-phenanthryl)indenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-methyl-4-(p-fluorophenyl)indenyl)}zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-methyl-4-(pentafluorophenyl)indenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-methyl-4-(p-chlorophenyl)indenyl)}zirconium dichloride,
rac-dimethylsilylene- bis{1-(2-methyl-4-(o,p-dichlorophenyl) phenyl-1-indenyl)} zirconium dichloride,
rac-dimethylsilylenebis{1-(2-methyl-4-(p-bromophenyl)indenyl)} zirconium dichloride,
rac-dimethylsilylenebis{1-(2-methyl-4-(p-tolyl)indenyl)}zirconium dichloride,
rac-dimethylsilylenebis{1-(2-methyl-4-(o,o'-dimethylphenyl)-1-indenyl)} zirconium dichloride,
rac-dimethylsilylenebis{1-(2-methyl-4-(p-ethylphenyl)indenyl)} zirconium dichloride,
rac-dimethylsilylenebis{1-(2-methyl-4-(p-benzylphenyl)indenyl)}zirconium dichloride,
rac-dimethylsilylenebis{1-(2-methyl-4-(p-biphenyl)indenyl)} zirconium dichloride,
rac-dimethylsilylenebis{1-(2-methyl-4-(p-trimethylsilylphenyl)indenyl)} zirconium dichloride,
rac-dimethylsilylenebis{1-(2-phenyl-4-phenylindenyl)} zirconium dichloride,
rac-diethylsilylenebis{1-(2-methyl-4-phenylindenyl)}zirconium dichloride,
rac-dicyclohexylsilylenebis{1-(2-methyl-4-phenylindenyl)}zirconium dichloride,
rac-methyphenyllsilylenebis{1-(2-methyl-4-phenylindenyl)}zirconium dichloride,
rac-diphenylsilylenebis{1-(2-methyl-4-phenylindenyl)} zirconium dichloride,
rac-di(p-tolyl)silylenebis{1-(2-methyl-4-phenylindenyl)} zirconium dichloride,
rac-di(p-chlorophenyl)silylenebis{1-(2-methyl-4-phenylindenyl)}zirconium dichloride,
rac-methylenebis{1-(2-methyl-4-phenylindenyl)} zirconium dichloride,
rac-ethylenebis{1-(2-methyl-4-phenylindenyl)} zirconium dichloride,
rac-dimethylgermylene-bis{1-(2-methyl-4-phenylindenyl)} zirconium dichloride,
rac-dimethylstanylene-bis{1-(2-methyl-4-phenylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)} zirconium dimethyl,
rac-dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)} zirconium methylchloride,
rac-dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)} zirconium chlorideSO2Me,
rac-dimethylsilylene-bis{1-(2-ethyl-4-phenylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-ethyl-4-(2-methyl-1-naphthyl)indenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-ethyl-4-(o-methylphenyl)indenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-ethyl-4-(2,3-dimethylphenyl) indenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-ethyl-4-(o-chlorophenyl)indenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-ethyl-4-(2,3-dichlorophenyl)indenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-ethyl-4-biphenylyl)indenyl)} zirconium dichloride,
rac-dimethylsilylenebis{1-(2-ethyl-4-(4-trimethylsilylphenyl)indenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-n-propyl-4-phenylindenyl)}zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-n-propyl-4-(2-methyl-1-naphthyl)indenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-n-propyl-4-(5-acenaphthyl)indenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-i-propyl-4-phenylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-i-propyl-4-(α-naphthyl)indenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-i-propyl-4-(8-methyl-9-naphthyl)indenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-s-butyl-4-phenylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-s-butyl-4-(α-naphthyl)indenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-s-butyl-4-(2-methyl-1-naphthyl)indenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-n-pentyl-4-phenylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-n-pentyl-4-(α-naphthyl)indenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-n-butyl-4-phenylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-n-butyl-4-(α-naphthyl)indenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-n-butyl-4-(2-methyl-1-naphthyl)indenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-i-butyl-4-indenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-i-butyl-4-(α-naphthyl)indenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-i-butyl-4-(2-methyl-1-naphthyl)indenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-neopentyl-4-phenylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-neopentyl-4-(α-naphthyl)indenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-n-hexyl-4-phenylindenyl} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-n-hexyl-4-(α-naphthyl)indenyl)} zirconium dichloride,
rac-methylphenylsilylene-bis{1-(2-ethxyl-4-phenylindenyl)} zirconium dichloride,
rac-methyphenyllsilylene-bis{1-(2-ethyl-4-(α-naphthyl)indenyl} zirconium dichloride,
rac-diphenylsilylene-bis{1-(2-ethyl-4-phenylindenyl} zirconium dichloride,
rac-diphenylsilylene-bis{1-(2-ethyl-4-(α-naphthyl)indenyl} zirconium dichloride,
rac-diphenylsilylene-bis{1-(2-ethyl-4-(4-biphenylyl)indenyl} zirconium dichloride,
rac-methylene-bis{1-(2-ethyl-4-phenylindenyl} zirconium dichloride,
rac-methylene-bis{1-(2-ethyl-4-(α-naphthyl)indenyl} zirconium dichloride,
rac-ethylene-bis{1-(2-ethyl-4-phenylindenyl} zirconium dichloride,
rac-ethylene-bis{1-(2-ethyl-4-(α-naphthyl)indenyl} zirconium dichloride,
rac-ethylene-bis{1-(2-n-propyl-4-(α-naphthyl)indenyl} zirconium dichloride,
rac-dimethylgermyl-bis{1-(2-ethyl-4-phenylindenyl} zirconium dichloride,
rac-dimethylgermyl-bis{1-(2-ethyl-4-(α-naphthyl)indenyl} zirconium dichloride
rac-dimethylgermyl-bis{1-(2-n-propyl-4-phenylindenyl} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-ethylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-n-propylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-t-butylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-cyclohexylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-methylcyclohexylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-phenylethylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-phenyldichloromethylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-chloromethylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-trimethylsilylmethylindenyl)} zirconium dichloride,
rac-diethylsilylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)} zirconium dichloride,
rac-di(i-propyl)silylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)} zirconium dichloride,
rac-methylphenylsilylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)} zirconium dichloride,
rac-methylphenylsilylene-bis{1-(2,7-dimethyl-4-t-butylindenyl)} zirconium dichloride,
rac-diphenylsilylene-bis{1-(2,7-dimethyl-4-t-butylindenyl)} zirconium dichloride,
rac-diphenylsilylene-bis{1-(2,7-dimethyl-4-ethylindenyl)} zirconium dichloride,
rac-di(p-tolyl)silylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)} zirconium dichloride,
rac-di(p-cholorophenyl)silylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2,3,7-trimethyl-4-ethylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2,3,7-trimethyl-4-i-propylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2,3,7-trimethyl-4-t-butylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2,3,7-trimethyl-4-cyclohexylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2,3,7-trimethyl-4-trimethylsilylmethylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2,3,7-trimethyl-4-trimethylsiloxylmethylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2,3,7-trimethyl-4-phenylethylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2,3,7-trimethyl-4-phenyldichloromethylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2,3,7-trimethyl-4-chloromethylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2,3,7-trimethyl-4-i-propylindenyl)} zirconium dichloride,
rac-di(cyclohexyl)silylene-bis{1-(2,3,7-trimethyl-4-i-propylindenyl)} zirconium dichloride,
rac-methylphenylsilylene-bis{1-(2,3,7-trimethyl-4-i-propylindenyl)} zirconium dichloride,
rac-diphenylsilylene-bis{1-(2,3,7-trimethyl-4-ethylindenyl)} zirconium dichloride,
rac-di(p-tolyl)silylene-bis{1-(2,3,7-trimethyl-4-i-propylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-methyl-4-i-propyl-7-methylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-methyl-4-i-propyl-7-methylindenyl)} zirconium-bis(methansulfonate),
rac-dimethylsilylene-bis{1-(2-methyl-4-i-propyl-7-methylindenyl)} zirconium-bis(p-phenylsulfinate),
rac-dimethylsilylene-bis{1-(2-methyl-3-methyl-4-i-propyl-7-methylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-methyl-4,6-di-i-propylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-methylindenyl)} zirconium dichloride,
rac-dimethylsilylene-bis{1-(2-methyl-4-i-propyl-7-methylindenyl)} titanium dichloride,
rac-dimethylsilylene-bis{1-(2-methyl-4-i-propyl-7-methylindenyl)} hafnium dichloride,
rac-dimethylsilylene-bis{1-(2-methyl-4,5-benzoindenyl)} zirconium dichloride,
rac-methyphenyllsilylene-bis{1-(2-methyl-4,5-benzoindenyl)} zirconium dichloride,
rac-diphenyllsilylene-bis{1-(2-methyl-4,5-benzoindenyl)} zirconium dichloride,
rac-diphenyllsilylene-bis{1-(2-methyl-α-acenaphthoindenyl)} zirconium dichloride,
rac-methylphenyllsilylene-bis{1-(2-methyl-α-acenaphthoindenyl)} zirconium dichloride,
rac-1,2-ethanediyl-bis{1-(2-methyl-4,5-benzoindenyl)} zirconium dichloride
and
rac-dimethylsilylene-bis{1-(4,5- benzoindenyl)} zirconium dichloride.
Compounds replacing the zirconium in the aforementioned compounds with titanium, hafnium, vanadium, niobium, chromium, tantalum, molybdenum or tungsten can also be cited as the examples of these transition metal compounds(A) represented by the formula (I).
In the process for manufacturing propylene polymers in the present invention, racemic form of the transition metal compound(A) represented by the formula (I) can usually be used as a compound of the catalyst. R form and S form of the compound may also be used.
Said transition metal compound(A) can be synthesized by the process described in the published references, for example Journal of Organometallic Chem. 288(1985), P.63-67, Laid-open European Patent Application 0,320,762, Laid-open Japanese Patent Application Hei4-268307, European Patent 549900 and Canadian Patent 2084017.
In the process for manufacturing propylene polymers in the present invention, the aforementioned transition metal compounds(A) can be used singly or in combination of two or more of them.
Given below is the explanation of the compound(B) having the ability for activating the aforementioned transition metal compound(A).
The component(B) may be at least one compound selected from
(B-1) an organoaluminum compound
(B-2) an organoaluminum oxycompound and
(B-3) a compound which reacts with said metallocene-type transition metal compound (A) to form an ionic pair
The organoaluminum compound represented by the following formula(B-1a) can be cited as organoaluminum compound (B-1): R⁶ _n AlX_3-n
In the above formula, R⁶ stands for a hydrocarbon group having 1 to 12 carbon atoms, X stands for halogen atom or hydrogen atom, and n is 1 to 3.
Examples of the hydrocarbon group having 1 to 12 carbon atoms include an alkyl group, a cycloalkyl group or an aryl group, specifically a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an isobutyl group, a pentyl group, a hexyl group, an octyl group, a cyclopentyl group, a cyclohexyl group, a phenyl group and a tolyl group.
Specific examples of the organoaluminum compound (c) include the following compounds:
trialkylaluminums such as trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, trioctylaluminum and tri(2-ethylhexyl)aluminum; alkenylaluminums such as isoprenylaluminum; dialkylaluminum halides such as dimethylaluminum chloride, diethylaluminum chloride, diisopropylaluminum chloride, diisobutylaluminum chloride and dimethylaluminum bromide; alkylaluminum sesquihalides such as methylaluminum sesquichloride, ethylaluminum sesquichloride, isopropylaluminum sesquichloride, butylaluminum sesquichloride and ethylaluminum sesquibromide; alkylaluminum dihalides such as methylaluminum dichloride, ethylaluminum dichloride, isopropylaluminum dichloride and ethylaluminum dibromide; alkylaluminum hydride such as diethylaluminum hydride and diisobutylaluminum hydride.
The compound represented by the following formula (B-1b) may be used as the organoaluminum compound (B-1): R⁶ _n AlY_3-n In the formula R⁶ is the same as described above; Y stands for the -OR⁷ group, the OSi(R⁸)₃ group, -OAl(R⁹)₂ group, -N(R¹⁰)₂ group, -Si(R¹¹)₃ group or -N(R¹²)Al(R¹³) group; n is 1 to 2; R⁷, R⁸, R⁹ and R¹³, which may be same or deferent, are methyl group, ethyl group, isopropyl group, isobutyl group, cyclohexyl group and phenyl group, for example; R¹⁰ is hydrogen atom, methyl group, ethyl group, isopropyl group, phenyl group and trimethylsilyl group, for example; and R¹¹ and R¹², which may be same or deferent, are methyl group and ethyl group, for example.
Specific examples of these organoaluminum compounds represented by the formula (B-1b) include the following compounds:
(1) compounds represented by R⁶ _n Al(OR⁷)_3-n such as dimethylaluminum methoxide, diethylaluminumethoxide and diisobutylaluminummethoxide
(2) compounds represented by R⁶ _nAl(OsiR⁸ ₃ )_3-n such as Et₂Al(OSiMe₃),
(iso-Bu)₂Al(OSiMe₃) and (iso-Bu)₂Al(OSiEt₃)
(3) compounds represented by R⁶ _nAl(OAlR⁹ ₂)_3-n such as Et₂AlOAlEt₂ and (iso-Bu)₂AlOAl(iso-Bu)₂
(4) compounds represented by R⁶ _nAl(NR¹⁰ ₂)_3-n such as Me₂AlNEt₂, Et₂AlNHMe, Me₂AlNHEt, Et₂AlN(SiMe₃)₂ and (iso-Bu)₂AlN(SiMe₃)₂
(5) compounds represented by R⁶ _nAl(SiR¹¹ ₃)_3-n such as (iso-Bu)₂ AlSiMe_3, and
(6) compounds represented by R⁶ _nAl(N(R¹²)AlR¹³ ₂)_3-n such as Et₂AlN(Me)AlEt₂ and (iso-Bu)₂AlN(Et)Al(iso-Bu)₂.
Out of the organoaluminum compounds represented by the aforementioned formula (B-1a) and (B-1b), the compound represented by the formula, R⁶ ₃Al, R⁶ _nAl(OR⁷)_3-n or R⁶ _nAl(OAlR⁹ ₂)_3-n, is preferable, and especially a compound represented by this formula wherein R6 is the iso-alkyl group and n is 2, is preferable.
Such organoaluminum compound may be used singly or in combination.
The component (B-2) alumiumoxy compound used in the present invention may be aluminoxane conventionally known to the public or an organoaluminumoxy compound insoluble in benzene sescribed in Laid-open Patent Publication HEI 2-78687.
The aluminoxane conventionally known to the public can be prepared by the following method, for example:
(1) Method in which an organoaluminum compound is added to a hydrocarbon medium suspension of a compound containing absorbed water or a salt containing crystal water, such as magnesium chloride hydrate, copper sulfate hydrate, aluminum sulfate hydrate, nickel sulfate hydrate and cerium chloride hydrate, to cause reaction.
(2) Method in which water, ice or steam is caused to act directly on an organoaluminum compound in a medium such as benzene, toluene, ethylether and tetrahydrofuran.
(3) Method in which an organotin oxide such as dimethyltinoxide and dibutyltinoxide is made to react with an organoaluminum compound in a medium such as decane, benzene and toluene.
Preferable examples of the organoaluminum compounds used in the preparation of aluminoxane include same compounds exemplified as the organoaluminum compounds (B-1), such as trialkylaluminums and tricycloalkylaluminum.
Examples of the solvent used in the manufacture of aluminoxan include aromatic hydrocarbons such as benzene, toluene, xylene, cumene and cymene; aliphatic hydrocarbons such as pentane, hexane, heptane, octane, decan, dodecan, hexadecan and octadecan; alicyclic hydrocarbons such as cyclopentane, cyclohexane, cyclooctane and methylcyclopentane; petroleum fractions such as gasoline, kerosine and gas oil; and halides of the aforementioned aromatic hydrocarbons, aliphatic hydrocarbons and alicyclic hydrocarbons, particularly chlorides and bromides. In addition, ethers such as ethyl ether and tetrahydrofuran. Out of these solvents, aromatic hydrocarbons are especially preferable.
Further, the aforementioned aluminoxan may contain a small amount of organic metal. Furthermore, the aluminoxan may be redissolved in the solvent after the solvent or any unreacted organoaluminum compound has been distilled and removed from the recovered solution of the aluminoxan.
Further, the benzene insoluble organoaluminum oxy compound that is used as the organoaluminum oxy compound (B-2) contains not more than 10%, preferably not more than 5%, especially preferably not more than 2%, in terms of Al atoms, of the Al component that is dissolved in benzene at 60°C and is insoluble or slightly soluble in benzene. The solubility of this organoaluminum oxy compound in benzene can be determined by suspending an organoaluminum oxy compound equivalent to 100 milligrams of Al atoms in 100 ml of benene, mixing them with agitation for 6 hours at 60°C, filtering them at 60°C by means of a G-5 glass filter with jacket, washing the solids remaining on the filter with 50 ml of benzene at 60°C four times, and then measuring the amount (x%) of the Al atoms (x millimols) which are present in all of the filtrates.
These organoaluminum compounds (B-2) may be used singly or in combination with not less than two of them.
Further, as examples of the compound (B-3) that reacts with the aforementioned transition metal compound (A) to form ion pairs, the Lewis acid, ionic compounds and carborane compounds which are disclosed in Japanese Laid-Open Patent Publication HEI 1-501950, Japanese Laid-Open Patent Publication HEI 1-502036, Japanese Laid-Open Patent Publication HEI 3-179005, Japanese Laid-Open Patent Publication HEI 3-179006, Japanese Laid-Open Patent Publication HEI 3-207703, Japanese Laid-Open Patent Publication HEI 3-207704, US Patent 547718, etc.
Specific examples of Lewis acid include triphenylboron, tris(4-fluorophenyl)boron, tris(p-tolyl)boron, tris(o-tolyl)boron, tris(3,5-dimethylphenyl)boron, tris(pentafluorophenyl)boron, MgCl₂, Al₂O₃ and SiO₂-Al₂O₃.
Specific examples of ionic compounds include triphenylcarbeniumtetrakis(pentafluorophenyl)borate, tri-n-butylammoniumtetrakis(pentafluorophenyl)borate, N, N-dimethylaniliumtetrakis(pentafluorophenyl)borate, and ferroceniumtetra(pentafluorophenyl)borate.
Specific examples of carborane compound include dodecaborane, 1-carbaundecaborane, bis-n-butylammonium(1-carbedodeca)borate, and tri-n-butylammonium(7,8-dicarbaundeca)borate and tri-n-butyl-ammonium(tridecahydrolide-7-carbaundeca)borate.
These compounds (b-3) may be used singly or in combination with not less than two of them.
In the present invention, as the compound (B) that can activates the transition metal compound (A), the aforementioned organoaluminum compound (B-1), organoaluminum oxy compound (B-2) and compound (B-3) may be used singly or in combination with not less than two of them.
A good example of a single-site catalyst in the present invention is a catalyst using the aforementioned metallocene transition metal compound (A). In the present invention hereinafter, such catalyst using the aforementioned metallocene transition metal compound (A), which is a good example of a single-site catalyst, is referred to as a metallocene-type catalyst. The metallocene-type catalyst that is used as the single-site catalyst of the present invention may be prepared by mixing the aforementioned transition metal compound (A) and the component (B) in an inactive hydrocarbon solvent or an olefin solvent.
As the inactive hydrocarbon solvent that us used in the preparation of the metallocene-type catalyst, for example, aliphatic hydrocarbons such as propane, butane, pentane, hexane, heptane, decane, dodecane and hexadecane, alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclopentane and cyclooctane, aromatic hydrocarbons such as benzene, toluene and xylene, halogenated hydrocarbons such as ethylene chloride, chlorobenzene and dichloromethane, petroleium fractions such as gasoline, kerosine and gas oil, and mixtures of these may be used.
In preparing the metallocene-type catalyst by using these components, the concentration of the transition metal compound (A) is preferably approx. 10^-8 to 10^-1 mol/liter (polymerization volume), more preferably 10 to 5 x 10^-2 mol/liter.
If the organoaluminum compound (B-1) and/or the organoaluminum oxy compound (B-2) is used as the compound (B), such compound(s) is used in such amount that the atom ratio (Al/transition metal) of the aluminum in the compound (B) to the transition metal of the transition metal compound (A) is normally 10 to 10,000, preferably 20 to 5,000.
When the organoaluminum compound (B-1) and the organoaluminum oxy compound (B-2) is used together, they are used preferably in such amount that the atom ratio (Al-1/Al-2) of the aluminum atoms (Al-1) in the compound (B-1) to the aluminum atoms in the compound (B-2) is 0.02 to 3, preferably 0.05 to 1.5.
If the compound (B-3) is used as the compound (B), it is used in such amount that the molar ratio ((A)/(B-3) of the transition metal compound (A) to the compound (B-3) is normally 0.01 to 10, preferably 0.1 to 5.
In the manufacture of a propylene polymer , the transition metal compound (A) and the compound (B) which comprise the metallocene-type catalyst may be mixed in the reactor during the manufacture of the propylene polymer , or a mixture of them previously prepared may be added to the reactor during the manufacture of the metallocene-type polymer.
If the transition metal compound (A) and the compound (B)are mixed before they are used, they may be brought into contact with each other at a temperature of normally - 50 to 150°C, preferably - 20 to 120°C, for 1 minute to 50 hours, preferably 5 minutes to 25 hours. Further, the mixing temperature may be changed at the time of mixing them to contact.
Further, the metallocene-type catalyst that is used in the manufacture of such propylene polymer may be a solid catalyst at least either of the transition metal compound (A) and compound (B) of which is supported by a granular or fine particle solid (carrier).
This carrier may be an inorganic or organic carrier. As an inorganic carrier, porous oxides such as SiO₂ and Al₂O₃, for example, are used preferably. Furthermore as an organic carrier, (co)polymers formed by using as the primary component any of the α-olefins having 2 to 14 carbon atoms, such as ethylene, propylene, 1-butene and 4-methyl-1-pentene, for example, or a polymer or copolymer formed by using as the primary component vinylcyclohexane, styrene, etc. may be used.
Further, the metallocene-type catalyst may also be used after forming a prepolymerized catalyst by prepolymerizing an olefin with the aforementioned transition metal compound (A) and the compound (B).
As the olefin that is used in the prepolymerization, olefins such as propylene, ethylene and 1-butene are used. Furthermore, these olefins may also be used in combination with other olefins.
Moreover, in the preparation of the metallocene-type catalyst, other components useful for the polymerization of propylene polymer , such as water as a catalyst component, may be used in addition to the aforementioned components.
The propylene polymer used in the present invention may be obtained by (co)polymerizing propylene and another olefin as required in the presence of a single-site catalyst such as the aforementioned metallocene-type catalyst so that a polymer having the aforementioned composition ratio may be produced.
The polymerization may be carried out by either liquid-phase polymerization method such as suspension polymerization and solution polymerization or gas-phase polymerization method.
In the liquid-phase polymerization method, the same solvent as the inactive hydrocarbon solvent that is used in the preparation of the catalyst may be used, and the polymerization monomer such as propylene may be used as the solvent.
In the case of carrying out the polymerization by the suspension polymerization method, it is desirable that the polymerization should be conducted at a temperature of -50 to 100°C, preferably 0 to 90°C. Furthermore, in the case of carrying out the polymerization by the solution polymerization method, it is desirable that the polymerization should be conducted at a temperature of 0 to 250°C, preferably 20 to 200°C. Moreover, in the case of carrying out the polymerization by the gas-phase polymerization method, it is desirable that the polymerization should be conducted at a temperature of 20 to 120°C, preferably 0 to 100°C and at a pressure of atmospheric pressure to 100 kg/cm², preferably atmospheric pressure to 50 kg/cm².
The polymerization may be conducted by any of the batch, semicontinuous and continuous processes. Moreover, the polymerization may be conducted in not less than two stages which reaction conditions are different.
The molecular weight of the propylene polymer thus obtained may be controlled to a desired range by causing hydrogen to be present in the polymerization system or changing the polymerization temperature or pressure.
Additives may be added to the propylene polymer of the present invention as optional component as required to the extent that will not frustrate the purpose of the present invention.
Examples of such additives include the heat stabilizers, weathering stabilizers, various stabilizers, antistatic agents, slip agents, anti-blocking agents, anti-fogging agents, lubricants, dyes, pigments, natural oil, synthetic oil and wax which are in the public domain.
Examples of stabilizers include anti-aging agents such as 2,6-di-t-butyl-4-methyl-phenyl(BHT); phenolic antioxidants such as tetrakis[methylene-3-(3,5-di-t-hydroxyphenyl)propionate]methane, β-(3,5-di-t-butyl-4-hydroxyphenyl)propionic acid alkylester, 2,2'-oxamidbis[ethyl-3-(3,5-di-t-hydroxyphenyl) propionate and such as Irganox 1010 (hindered phenolic antioxidant: trade name); fatty acid metal salts such as zinc stearate, calcium stearate and 1,2-hydroxycalcium stearate; and multi-valent alcohol fatty acid esters such as glycerin monostearate, glycerin distearate, pentaerythritol monostearate, pentaerythritol distearate and pentaerythritol tristearate. These may also be used in combination with one another.
The propylene polymer of the present invention may also contain fillers such as silica, diatomaceous earth, alumina, titanium oxide, magnesium oxide, pumice powder, pumice balloon, aluminum hydroxide, magnesium hydroxide, basic magnesium carbonate, dolomite, calcium sulfate, potassium titanate, barium sulfate, calcium sulfite, talc, clay, mica, asbestos, calcium silicate, monmorillonite, bentonite, graphite, aluminum powder and molybdenum sulfide.
The propylene polymer and said additives as optional component may be mixed by using the method known to the public.
Further, the propylene polymer used in the present invention may be mixed in the presence of an organic peroxide so that its MFR will be controlled to a desired value. The propylene polymer and such peroxide may be mixed in the presence of the aforementioned components as optonal; or propylene polymer and such peroxide may be mixed first and then mixed with such other components.
Examples of such organic peroxide include ketone peroxides such as methylethylketone peroxide and cyclohexanon peroxide; peroxyketals such as 1,1-bis(t-butylperoxy)cyclohexane and 2,2-bis(t-butylperoxide)octane; hydroperoxides such as t-butylhydroperoxide, cumenehydroperoxide, 2,5-dimethylhexane-2,5-dihydroxyperoxide and 1,1,3,3-tetramethylbutylhydroperoxide; dialkylperoxides such as di-t-butylperoxide, 2,5-dimethyl-2,5-di-(t-butylperoxy)hexane (trade name: Perhexine 25B) and 2,5-dimethyl-2,5-di(t-butylperoxy)hexine-3; diacylperoxides such as rauroylperoxide and benzoylperoxide; and peroxyesters such as t-butylperoxyacetate, t-butylperoxybenzoate and 2,5-dimethyl-2,5-di(benzoylpeoxide)hexane.
Such peroxide may be used in such amount that the ratio of the peroxide to 100 parts by weight of the propylene polymer is normally 0.01 to 1 part by weight, preferably 0.05 to 0.5 parts by weight.

Ethylene polymer :

The ethylene polymer that may be used in the present invention is a homopolymer of ethylene or a copolymer of ethylene and another α-olefin. As an example of such another olefin, α-olefins having 3 to 20 carbon atoms may be cited. Preferable examples are α-olefins having 3 to 8 carbon atoms such as propylene, 1-butene, 1-pentene, 1-hexene and 1-octene. These α-olefins may be used in combination with not less than two of them.
The MFR of the ethylene polymer is preferably 20 to 100 g/10 minutes, more preferably 20 to 60 g/10 minutes, much more preferably 30 to 60 g/10 minutes. In the present invention, the MFR of the ethylene polymer is determined at 190°C under a load of 2.16 kg in accordance with ASTM D1238.
The ratio Mw/Mn of the weight average molecular weight (Mw) to the number average molecular weight of the ethylene polymer of the present invention is preferably not more than 4, more preferably not more than 3.5, especially preferably 1.5 to 3.5, from a viewpoint of spinnability and the fiber strength of conjugate fibers and fastness to rubbing.
The density of the ethylene polymer of the present invention is preferably 0.92 to 0.97 g/cm³. From a viewpoint of softness and fastness to rubbing, the density is more preferably 0.94 to 0.96 g/cm³, much more preferably 0.94 to 0.955 g/cm³, most preferably 0.940 to 0.955 g/cm³.
The ethylene polymer of the present invention may optionally contain other polymers and additives such as colorants, heat stabilizers, nucleators and lubricants. Examples of colorants include inorganic colorants such as titanium oxide and calcium carbonate and organic colorants such as phthalocyanine. Examples of heat stabilizers include phenol-based stabilizers such as BHT (2,6-di-tert-butyl-4-methylphenol).

Conjugate Fibers:

The conjugate fibers of the present invention, comprising not less than two types of fiber components, are conjugate fibers at least part of the structure of which is composed of a propylene polymer. The fibers of the present invention may be the fibers the whole of which is composed of not less than two types of propylene polymers with different properties or only part of which is composed of a propylene polymer. Examples of these conjugate fibers include various conjugate fibers of core-sheath, sandwich, side-by-side, sea island and other types, at least part of the structure of which is composed of a propylene polymer.
In the present invention, particularly the conjugate fibers of a core-sheath type comprising the core made of a propylene polymer and the sheath made of an ethylene polymer and the conjugate fibers of a side-by-side type comprising a monofilament formed by the fiber part made of a propylene polymer and the fiber part made of ethylene polymer being arranged in parallel with or being entangled are preferable as they meet both of the requirements for softness and strength.
The denier of the conjugate fibers of the present invention is not more than 3.0 d, preferably not more than 2.5 d since non-woven fabrics having excellent softness can be obtained at such denier.
In the present invention, the propylene polymer constituting the conjugate fibers is the aforementioned propylene polymer, especially preferably the propylene polymer manufactured by a single-site catalyst having the aforementioned characteristics.
Further, as the component of the conjugate fibers other than the propylene polymer, an ethylene polymer is preferable. As the ethylene polymer, the aforementioned ethylene polymer is used preferably.

Conjugate Fibers of the Core-Sheath Type:

Conjugate fibers of the core-sheath type have such structure that the core is enveloped inside the sheath in a concentric or eccentric manner or arranged in parallel with the sheath. Especially the concentric type or the eccentric type in which the propylene polymer constituting the core is not exposed is preferable. Further, out of the conjugate fibers of the side-by-side type, those conjugate fibers whose propylene polymer content is low are preferable.
In the present invention, the polymer constituting the core of conjugate fibers is preferably the aforementioned propylene polymer.
The polymer constituting the sheath of conjugate fibers is preferably the aforementioned ethylene polymer.
In the present invention, the conjugate fibers whose core part is a propylene polymer manufactured by use of the aforementioned single-site catalyst having a molecular weight distribution (Mw/Mn) of 1.5 to 3.5 and whose sheath part is an ethylene polymer is recommended as the most preferable conjugate fibers.
conjugate fibers. In this case, it is more preferable that the propylene polymer is a random copolymer of propylene and a small amount of ethylene which contains 0.1 to 5.0 mol%, preferably 0.2 to 4.0 mol%, more preferably 0.5 to 3.0 mol%, of the structural unit deriving from ethylene.
In the conjugate fibers of the core-sheath type having such structure, the propylene polymer manufactured by a single-site catalyst shows excellent spinnability and fiber strength, the propylene polymer and the ethylene polymer being selected to build up the core-sheath structure, and consequently the conjugate fibers exhibit the overall properties that produce the effects unavailable with the conventional conjugate fibers which meet the requirements of being easy to making fibers with the target small denier and soft and having a good feel and adequate strength.
The ethylene polymer constituting the sheath which contains 0.1 to 0.5 wt% of a lubricant is preferable since it enables conjugate fibers to show excellent fastness to rubbing. Examples of such lubricant include oleic amide, erucic amide and stearic amid.
The weight ratio of propylene polymer/ethylene polymer of the conjugate fibers of the core-sheath type is 5/95 to 95/5, preferably 5/95 to 20/80, more preferably 10/90 to 20/80 since such ratio makes it easy to make fibers soft. If the ratio of the propylene polymer to the conjugate fibers is less than 5, the fiber strength may not be improved. On the other hand, if the ratio of the propylene polymer to the conjugate fibers is more than 20, the non-woven fabrics comprising the conjugate fibers of the core-sheath type may show unsatisfactory softness.

Non-woven Fabrics:

The present invention also provides non-woven fabrics comprising the aforementioned conjugate fibers. The non-woven fabrics of the present invention are made up of the aforementioned conjugate fibers.
The non-woven fabrics of the present invention preferably have the non-woven fabrics the sum of the bending resistance in the longitudinal direction and that in the transverse direction of not more than 80 mm. In the present invention, the bending resistance is a value that is determined by the Clark method (JIS L1096 Method C). In the present invention, the longitudinal direction refers to the direction parallel with the direction of flow of the web at the time of the formation of the non-woven fabric, and the transverse direction refers to the direction perpendicular to the direction of the flow of the web.
The unit weight of the non-woven fabrics is normally not more than 25 g/m². These are suitable for those applications requiring softness, such as the applications for the material of the back sheet of disposable diapers, for example. However, depending on applications, non-woven fabrics having higher unit weight may be used. For example, such non-woven fabrics having a higher unit weight are suitable for such applications as wrapping cloth and medical cover cloth.
For the non-woven fabrics, the aforementioned core -sheath structure conjugated fibers are most preferable.
Given below is an explanation made of the manufacture of the non-woven fabrics comprising the conjugate fibers of the present invention. The specific example is the case in which the conjugate fibers of the core-sheath type is used as conjugated fibers.
An especially preferable embodiment of the non-woven fabrics of the present invention is the non-woven fabric (1) comprising the conjugate fibers of a core-sheath type (i) which comprise at a weight ratio of 5/95 to 20/80 (a)the propylene polymer constituting the core part obtained by a single site catalyst having a molecular weight distribution (Mw/Mn) of 1.5 to 3.5, an MFR of 20 to 100 g/10 min. and an ethylene content of 0.5 to 5.0 mol% and (b) the ethylene polymer constituting the sheath part which has an MFR of 20 to 60 g/10 min. and a density of 0.92 to 0.97 g/cm³ and (ii) which have a denier of not more than 3.0 d and (2)having the sum of the bending resistance in the longitudinal direction and that in the transverse direction of which is not more than 80 mm as determined by the Clark method (JIS L1096 Method C). This non-woven fabric may be partially bonded by thermocompression.
The conjugate fibers of the core-sheath type are spun by melting the propylene polymer constituting the core of the conjugate fibers of the core-sheath type and the ethylene polymer constituting the sheath in separate extruders, etc. and causing them being extruded through a spinneret having a conjugate fiber spinning nozzle so constructed that each extrude from such extruder, etc. is formed into a desired core-sheath structure. The conjugate fibers thus spun are cooled in a cooling fluid, further given tension by stretching air to give a desired denier, and collected and piled up on the collecting belt to a desired thickness and then caused to be entangled by conventional methods.
As the entangling method, varions methods including the heat embossing method using embossing rolls, heat fusion method using ultrasonic waves, method in which the fibers are entangled by means of water jet, method using hot air through and method using needle punching, for example, may be used according to circumstances. Out of these, the method in which the fibers are partially bonded by thermocompression by subjecting them to heat embossing treatment by use of rolls is preferable especially since non-woven fabrics having excellent fastness to rubbing are obtained by this method. The ratio (embossed area ratio) of the thermocompressed part to the total non-woven fabric may be determined as appropriate according to applications, and the ratio ranging from 5 to 40% is normally preferable since non-woven fabrics showing an excellent balance among softness, air permeability and fastness to rubbing.
Even in the case of using conjugate fibers other than conjugate fibers of the core-sheath type, the aforementioned manufacturing methods may be used to manufacture non-woven fabrics.
Since the non-woven fabrics of the present invention are soft and have an excellent feel and high fastness to rubbing, they can be used suitably as packaging materials, materials for clothing, materials for diapers, etc.
Because of their characteristics of softness, excellent feel and fastness to rubbing, the non-woven fabrics of the present invention can be used suitably as the materials for the back sheet, top sheet, size gather of disposable diapers. Especially in the case of using the non-woven fabrics as the materials for the back sheet and size gather of disposable diapers, the non-woven fabrics may preferably be used in the form of a laminate obtained by laminating the non-woven fabrics and permeable film. As such permeable film, film having the properties that do not permiate liquids such as water but permeate gases such as steam and air is preferable.
As such permeable film, films known to the public may be used, and there is no special restriction. Examples of such film include the permeable films that are obtained by forming film by adding a filler, preferably having particle size of 0.1 to 7 mm, to a thermoplastic resin and then stretching the film monoaxially or biaxially at a stretching ratio of at least not less than 1.5 times, preferably not less than 1.5 times but not more than 7 times. Out of these films, porous polyolefin film is preferable because of its excellent adhesion to the non-woven fabrics of the present invention and the excellent flexibility of the film itself.
The polyolefin-based resin which is the material for the aforementioned porous polyolefin film is a homopolymer or copolymer of α-olefin having not less than two carbon atoms such as ethylene, propylene and 1-butene. Specific examples of such polyolefin-based resin include polyethylenes such as high density polyethylene, medium density polyethylene, low-pressure low-density polyethylene (linear low density polyethylene) and high-pressure low-density polyethylene, polypropylene, propylene-ethylene random copolymer and poly-1-butene. Out of these, low-pressure low-density polyethylene and high-pressure low-density polyethylene, particularly low-pressure low-density polyethylene, are preferable since they provide the non-woven fabric of the present invention which has no rough feel.
Further, laminates whose porous polyolefin film is a film having a porosity (ratio of the volume of pores to the apparent volume of the film) of not less than 30% and a moisture permeability of 2,000 to 7,000 g/m²/24 hr (as determined by JIS P0208) are preferable for the materials for diapers.

EXAMPLES

Tthe following Examples and Comparative Examples illustrated below are to explain embodiments of the present invention. However, it is to be understood that the present invention is not intended to be limited to the embodiments.
The determination of the filament strength and bending resistance of the following Examples and Comparative Examples and the evaluation of the spinnability thereof were made by the following methods:

Filament Strength:

Filament strength was determined in accordance with JIS L1019 and JIS L1069.

Bending Resistance:

The bending resistances in the direction (longitudinal direction: MD) parallel with the direction of flow of the web at the time of the formation of the non-woven fabric and in the direction (transverse direction: CD) of the flow of the web was determined by the Clark method (JIS L1096 Method C). The sum of the two resistances was taken as the bending resistance of the non-woven fabric.

Spinnability:

Spinnability at the time of the formation of non-woven fabrics was evaluated by the following criteria:

○: Good
Δ: Spinning is possible, but the breakage of filament is apt to occur.
X: Spinning is impossible.

Examples 1 through 10:

In each of the Examples, a non-woven fabric having an embossed area ratio of 15% and a unit weight of 23 g/m² was obtained i) by obtaining a filament having a denier of 2 to 3 d by supplying resins as shown in Tables 1 through 4 as the material for the core and sheath into separate extruders, melting and mixing them, and spinning conjugate fibers at a discharge rate of 1.0 g/minute per orifice through a spinneret having 1,093 orifices of 0.6Ø and ii) by allowing the fibers to accumulate on the collecting surface and then causing them to be entangled by heat embossing rolls.
The resins A for the core are propylene polymers manufactured by a metallocene catalyst having MFR of 60 g/10 minutes and an ethylene content of 0.0, 4.0 and 4.9 mol% respectively. The resins B for sheath material are polyethylene resins (available from Mitsui Chemicals, Inc.; trade names: ULTZEX, NEO-ZEX and HI-ZEX) having an MFR of 30 g/10 minutes and a density of 0.920, 0.945, 0.948 and 0.960 g/cm³ respectively.
The spinnability at the time of the manufacture of the non-woven fabric was evaluated, and the filament strength and bending resistance of the non-woven fabrics thus obtained were determined. The results are shown in Tables 1 through 4.

Comparative Example 1:

Non-woven fabrics were produced by the same manner as described in Example 1 except that a propylene polymer (MFR: 60 g/10 minutes) manufactured by use of a Ziegler catalyst which had an ethylene content of 0.5 mol%. The results are shown in Table 1.

	Unit	Comparative Example 1	Example 1	Example 2	Example 3
Resin A Core material	Catalyst	-	Ziegler	Metallocene	Metallocene	Metallocene
MFR	g/10min	6 0	6 0	6 0	6 0
Mw/Mn	-	3.6	2.1	2.1	2.1
Ethylene content	mol%	0.5	0.0	0.5	4.9
Resin B Sheath material	M F R	g/10min	3 0	3 0	3 0	3 0
Mw/Mn	-	3.0	3.0	3.0	3.0
Density	g/cm3	0.948	0.948	0.948	0.948
A/B weight ratio		20/80	20/80	20/80	20/80
Denier	d	2. 0	1.8	1. 8	2. 0
Filament strength	g/d	1.8	2.4	2.4	2.2
Bending resistance (MD+CD)	mm	8 0	8 0	8 0	7 5
Spinnability	-	Δ	○	○	○

	Unit	Example 4	Example 5
Resin A Core material material	Catalyst	-	Metallocene	Metallocene
MFR	g/10min	6 0	6 0
Mw/Mn	-	2.1 2.1	2.1 2.1
Ethylene content	mol%	0.5	0.5
Resin B Sheath material	MFR	g/10min	30	30
Mw/Mn	-	3. 0	3. 0
Density	g/cm3	0.948	0.948
A/B weight ratio	-	5/95	10/90
Denier	d	1.9	1.8
Filament strength	g/d	2. 2	2. 4
Bending resistance (MD+CD)	mm	7 0	7 5

	Unit	Example 6	Example 7	Example 8
Resin A Core material	MFR	g/10min.	6 0	6 0	6 0
Mw/Mn	-	2. 0	2.0	2.5
Ethylene content	mol%	0.5	0.5	0.5
Resin B Sheath material	MFR	g/10min.	3 0	3 0	2 0
Mw/Mn	-	3.0	3.0	3.0
Density	g/cm3	0.945	0.948	0.948
A/B weight ratio	-	20/80	20/80	20/80
Denier	d	2. 0	2.0	2.0
Bending resistance (MD+CD)	mm	8 0	8 0	8 0

	Unit	Example 9	Example 10
Resin A Core Material	MFR	g/10 min	6 0	6 0
Mw/Mn	-	2 . 5	2 . 5
Ethylene content	mol%	4.0	4.9
Resin B Sheath Material	MFR	g/10 min	2 0	2 0
Mw/Mn	-	3.0	3.0
Density	g/cm3	0.948	0.948
A/B weight ratio	-	20/80	20/80
Denier	d	2.0	2.0
Bending resistance (MD+CD)	mm	7 6	7 0

Claims

Conjugate fibers at least a part which comprise a propylene polymer obtained by use of a single site catalyst and having a molecular weight distribution (Mw/Mn) of 1.5 to 3.5.
Conjugate fibers as defined in Claim 1, which comprise the aforementioned propylene polymer and an ethylene polymer .
Conjugate fibers as defined in Claim 2, wherein the aforementioned propylene polymer is a polymer having an MFR of 20 to 100 g/10 min. and containing an ethylene component of 0.5 to 5.0 mol%.
Conjugate fibers as defined in Claim 2 , wherein the aforementioned ethylene polymer is a polymer having an MFR of 20 to 60 g/10 min. and a density of 0.92 to 0.97 g/cm³.
Conjugate fibers as defined in any of Claim 2 to 4, which has a core-sheath structure, whose core parts comprise the aforementioned propylene polymer and whose sheaths comprise an ethylene polymer.
Conjugate fibers as defined in any of Claim 2 to 4, which has a side-by-side structure containing the fiber part comprising the aforementioned propylene polymer and the fiber part comprising an ethylene polymer .
Non-woven fabrics comprising the conjugate fibers as defined in any of Claims 1 to 6.
Non-woven fabrics as defined in Claim 7, wherein the conjugate fibers comprise the part comprising the propylene polymer and the part comprising an ethylene polymer at a weight ratio of 5/95 to 20/80 and have a denier of not more than 3.0 d.
Non-woven fabrics as defined in Claim 7, wherein the non-woven fabrics have the sum of the bending resistance in the longitudinal direction and that in the transverse direction of which is not more than 80 mm as determined by the Clark method (JIS L1096 Method C).
Non-woven fabrics as defined in Claim 9, wherein the part comprising the aforementioned propylene polymer and the part comprising an ethylene polymer constitute conjugate fibers of a core-sheath type.
Non-woven fabrics as defined in Claim 9, wherein the part comprising the aforementioned propylene polymer and the part comprising an ethylene polymer constitute conjugate fibers of a side-by-side type.
Non-woven fabrics as defined in Claim 7, which is partially bonded by thermocompression.
Non-woven fabrics

comprising the conjugate fibers of a core-sheath type which comprise at a weight ratio of 5/95 to 20/80 the propylene polymer constituting the core part obtained by a single site catalyst having a molecular weight distribution (Mw/Mn) of 1.5 to 3.5, an MFR of 20 to 100 g/10 min. and an ethylene content of 0.5 to 5.0 mol% and the ethylene polymer constituting the sheath part having an MFR of 20 to 60 g/10 min. and a density of 0.92 to 0.97 g/cm³ and which have a denier of not more than 3.0 d, and

having the sum of the bending resistance in the longitudinal direction and that in the transverse direction of which is not more than 80 mm as determined by the Clark method (JIS L1096 Method C).
Non-woven fabrics as defined in Claim 13, which is partially bonded by thermocompression.