CA1189227A - Multiphase core//shell polymers - Google Patents
Multiphase core//shell polymersInfo
- Publication number
- CA1189227A CA1189227A CA000389209A CA389209A CA1189227A CA 1189227 A CA1189227 A CA 1189227A CA 000389209 A CA000389209 A CA 000389209A CA 389209 A CA389209 A CA 389209A CA 1189227 A CA1189227 A CA 1189227A
- Authority
- CA
- Canada
- Prior art keywords
- core
- weight
- shell
- parts
- polymer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/12—Powdering or granulating
-
- 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
- C08F291/00—Macromolecular compounds obtained by polymerising monomers on to macromolecular compounds according to more than one of the groups C08F251/00 - C08F289/00
- C08F291/02—Macromolecular compounds obtained by polymerising monomers on to macromolecular compounds according to more than one of the groups C08F251/00 - C08F289/00 on to elastomers
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/12—Powdering or granulating
- C08J3/126—Polymer particles coated by polymer, e.g. core shell structures
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L77/00—Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Compositions of derivatives of such polymers
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2355/00—Characterised by the use of homopolymers or copolymers, obtained by polymerisation reactions only involving carbon-to-carbon unsaturated bonds, not provided for in groups C08J2323/00 - C08J2353/00
- C08J2355/02—Acrylonitrile-Butadiene-Styrene [ABS] polymers
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2425/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Derivatives of such polymers
- C08J2425/02—Homopolymers or copolymers of hydrocarbons
- C08J2425/04—Homopolymers or copolymers of styrene
- C08J2425/06—Polystyrene
-
- 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
- Y10T428/2982—Particulate matter [e.g., sphere, flake, etc.]
- Y10T428/2991—Coated
- Y10T428/2998—Coated including synthetic resin or polymer
Abstract
ABSTRACT
A multiphase core//shell polymer comprising a crosslinked elastomer core and a rigid thermoplastic polymer shell comprising a mono alkyl maleate or fuma-rate, styrene and optionally a monomer selected from the group consisting of C1 to C8 alkyl acrylates and meth-acrylates, acrylonitril? and methacrylonitrile. The core has an average particle diameter in the range of about 0.3 to about 0.8 micron and the rigid shell has a thick-ness of at least about .025 micron. The multiphase core//shell polymers are useful for blending with poly-amides to provided toughened polyamide compositions.
A multiphase core//shell polymer comprising a crosslinked elastomer core and a rigid thermoplastic polymer shell comprising a mono alkyl maleate or fuma-rate, styrene and optionally a monomer selected from the group consisting of C1 to C8 alkyl acrylates and meth-acrylates, acrylonitril? and methacrylonitrile. The core has an average particle diameter in the range of about 0.3 to about 0.8 micron and the rigid shell has a thick-ness of at least about .025 micron. The multiphase core//shell polymers are useful for blending with poly-amides to provided toughened polyamide compositions.
Description
'7 MULTIPHASE CORE//SHELL POLYMERS
. _ BACKGROUND OF THE INVENTION
l. yield of the Invention This invention relates to multiphase core//shell polymers and more particularly to multiphase core//shell polymers containing a rigid shell comprising styrene and a monoalkyl maleate or fumarate~ used Jo enhance the im-pact resistance and ductility of polyamides.
. _ BACKGROUND OF THE INVENTION
l. yield of the Invention This invention relates to multiphase core//shell polymers and more particularly to multiphase core//shell polymers containing a rigid shell comprising styrene and a monoalkyl maleate or fumarate~ used Jo enhance the im-pact resistance and ductility of polyamides.
2. Desc_ lion of tb- Rio- Ar 10There is much prior art concerned with improving the impact strength of polyamides. variety oE additives have been added to polyamides with some improvQmen~ in toughness being obtained. Many of the additives are elastomeric in nature. For example, Owens et l U.S.
15Patent 3,~8,274 teaches modestly improved impact strength of polyamides modified with (A) a first cross-linked elastomer phase of copolymers or terpolymers and (B) a final rigid phase thermoplastic stage containing amine-reactive moieties, preferably carboxylic acid groups. The soft modifier is coated with a rigid layer thus apparently negating a large improvement in polyamide toughness Dunkelberger, U.~. Patent 4,167,5~5, recognizes that the polymer modifiers of Owens et al impart improvement in the impact strength of higher molecular weight posy-,~., amides but that the resulting blends do not exhibit the good flow necessary for injection molding operations and teaches that Owens' core//shell polymers having high rubber core content are not capable of being admixed and dispersed in low molecular weight nylon due to the very low viscosity of nylon above the melting point and the resulting difficulty of dispersing a viscous component in a fluid medium due to insufficient shear.
Another approach to the problem o enhancing the toughness of polyamides is provided by Epstein, U.S.
Patent 4,17A,358. Toughened multiphase polyamides were obtained by incorporating elastomers modified by copoly-merization or reaction with monomers containing func tional groups such as carboxy groups capable of reaction or hydrogen-bonding with polyamides. This approach has been used with acrylates, polyethylenes, ethylene propy-lene rubbers, ethylene propylene diene rubbers and ethy-lene vinyl acetate copolymers. The resulting function-alized bulk rubbers or elastomers require very intensive20 shear in order to be finely dispersed in a polyamide matrix. The rubbers must, therefore, be soluble (i.e., not crosslinked) in order to permit flow and dispersion on heating. Since the rubber particles are soluble and deEormable, their final size is largely dependent on intensity o shear on extrusion and molding. The desired fine rubber dispersions are difficult to obtain without intensive shear, and control of rubber particle si2e in the final molding is not easily obtained.
Humme et al, U.S. Patent ~,221,~79, discloses impact-resistant polyamides consisting substantially of a poly-amide and a graft product of a polybutadiene as a graft substrate and a mixture of an acrylate or methacrylate, and acrylonitrile and/or acrylamide monomers grafted thereon. The grafted shell is generally elastomeric in nature. 5ra,t products containing a rigid shell such as a styrene copolymer shell are found to be unsatisfactory apparently because of poor compatibility with the poly-amide.
~89~7 SUMMARY OF THE INVENTION
According to one embodiment o:E this invention, there is provided a multiphase core//shell polymer comprising about 50 to about 90 pa.rts by weight oE a cross-linked elastomer core and about 10 to about 50 parts by weight of a rigid thermoplas-tic polymer shell of glass transition temperature at least about 35C., comprising from about 1 to about 25 parts by weight of an interpolymerized Cl to C4 monoalkyl maleate or fumarate, from about 20 to about 80 parts by weight oE inter-polymerized styrene, from about 0 to about 79 pa.rts by weight of an .interpolymerized Cl to C8 alkyl acrylate or methacry-late and rom about 0 to about 45 parts by weight of interpoly-merized acrylonitrile or methacrylonitrile based on 100 parts by weight of shell interpolymer, wherein the multiphase core//shell polymer has a core of weight average particle dia-meter of at least about 0.3 micron and a rigid shell of average thickness of at least about 0.025 micron.
The multiphase core//shell polymers are used for toughening polyamidesO
In accordance with another embodiment of this inven-tion, there is provided a process of preparing a multiphase core//shell polymer which comprises preparing an aqueous emul-sion of an elastomeric core polymer oE weight average particle size in the range oE at least about 0.3 micron; graft polymeriz-ing on the elastomeric core a rigid shell comprising from about l to about 25 parts by weight of an interpolymerized Cl to O monoalkyl maleate or fuma.rate~ from about 20 to about 80 parts by weight of interpolymerized styrene, from about 0 to about 79 parts by weight oE an interpolymerized Cl to O
alkyl acrylate or methacrylate and from about 0 to about 45 parts by weight of interpolymerized acryloni-trile or methacrylo-.~
2~7 - 3a -nitrile per 100 parts by weight of shell interpolymer, wherein the rigid shell has a glass transition temperature of at least 35C. and is of average thickness at least about 0.025 micron and wherein the weight ratio of core to shell is in the range oE about 9:1 to about 1:1; and recovering the multiphase core//shell polymer from the aqueous emulsion.
DETAILED DESCRIPTION OF THE INVENTION
The polyamide resins which are toughened by the multiphase core//shell compositions of this inven-tion, are well known in the art and embrace those semi-crystalline and amorphous resins having a number average molecular weight in the range of about 5000 to 30,000 commonly referred to as nylons. PreEerably the molecu-lar weight is in the range oE about 8,000 to 20,000.
Suitable polyamides include -those described in U. S.
Pat. NosO 2,071,250; 2,071,251; 2,130,523; 2,130,948;
2,241,322; 2,312,966; 2,512, 606; and 3,393,210. The polyamide resin can be produced by condensa-tion of equi-molar amounts of a saturated dicarboxylic acid contain-ing from 4 to 12 carbon atoms with a diamine, in which the diamine contains Erom 4 to 14 carbon atoms. Excess diamine can be employed to provide an excess of amine end groups over carboxyl end groups in -the polyamide.
Examples oE polyamides include polyhexamethylene adipamide ~66 nylon), polyhexamethylene azelamide (69 nylon), polyhexamethylene sebacamide (610 nylon), polyhexamethylene dodecanoamide ,, .~
(612 nylon) and bis (paraaminocyclohexyl) methane dodeca-noamide. The polyamide resin can also be produced by ring opening of lactams, for example polycaprolactam and polylauric lactam, and by condensation of -amino-car-S boxylic acids, for example, poly-ll-aminoundecanoic acid.
It is also possible to use in this invention polyamides prepared by the copolymerization of two of the above polymers or terpolymerization of the above polymers or their components, e.g~, for example, an adipic, iso-phthalic acid hexamethylene diamine copolymer. Prefer-ably the polyamides are linear with a melting point in excess of 2~C. As yreat as 99 percent by weight of the composition can be composed of polyamide; however, pre-ferred compositions contain from 55 to 99 percent, and more narrowly ~5 to 90 percent, by weight of polyamide.
The molecular weight of the polyamide is selected in the range of 5000 to 3~,00~ number average, preferably 80~0 to 2~,~0~ to provide polyamide compositions which can be readily molded by injection or extrusion tech-niques The multiphase core//shell polymer of the present invention is an elastomer based composite interpolymer material having a crosslinked elastomer core and a rigid thermoplastic polymer shell.
The elastomer core can be a tone elastomer, an ethylene-propylene-diene rubber, an acrylic e]stomer, or a polyurethane elastomer. The diene elastomers include polybutadiene, polyisoprene, polychloroprene and poly-(cyanobutadiene~. The diene may be copolymerized with up to about 50 weight percent of other monomers such as alkyl acrylates and methacrylates, styrene, -methyl-styrene, acrylonitrile and substituted acrylonitriles, vinyl ethers, vinyl amides, vinyl esters and the like.
The acrylic elastomers comprise 5~ to 99O9 parts by weight ox an alkyl acrylate containing 1 to l carbon atoms, preferably 2 to carbon atoms, 0 to 4~ parts by weight of other ethylenically unsaturated monomers and .1 to 5 parts by weight of a polyunsaturated cross-linking monomer such as polyacrylic and polymethacrylic 2'7 -5- C-08~12-1182 esters of polyols such 3S butylene diacrylate and di~eth-acrylate, trimethylolpropane trimethacrylate and tne like, vinyl acrylate and methacrylate, divinyl and tri-vinyl benzene and the like. Optionally from about 001 to5 about 5 parts by weight o a graft-linking monomer with two or more addition polymerizable unsaturated groups which participate in polymerization at different rates, may also be included. It is preferred that the graft-linking monomer has at least one reactive group which polymerizes at about the same rate, or slightly slower than the other monomers, while the remainirlg reactive group or groups polymerize at a substantially slower rate. The differential polymerization rates result in a residual level of unsaturation in the elastomer core, particularly during the latter stages of polymerization and, consequently, at or near the surface of the elasto-mer particles. When the rigid thermoplastic shell is subsequently polymerized at the surface of the elastomer, the residual unsaturated addition-polymerizable reactive groups contributed by the graft-linking monomer partici-pate in the subsequent reaction so that at least a por-tion of the rigid shell is chemically attached to the surface of the elastomer. The crosslinked elastomer core preferably has a glass transition temperature below about -25C and a swelling index ranging from about 2 to about 20 determined in a good "solvent" for the elastomer, i.e.
a solvent which has a solubility parameter close to the solubility parameter of the polymer and is similar in polarity and hydrogen-bonding ability. Thus for poly-butadienes, suitable solvents for determination ofswelling index include benzene, to]uene and tetrahydro-furan and for acrylic elastomers, suitable solvents include acetone, benzene and toluene.
The elastomeric core is prepared in bulk, in emulsion or in solution. Those prepared in bulk or solution are converted into aqueous emulsion by known techniques prior to the addition polymerization of -the rigid polymer shell thereto.
The rigid thermoplastic polymer shell has a glass '7 -6- C-08~12-1182 transition temperature of at least ahout 35 C ~n~ com-prises a monomaleate or monofumarate of a Cl to C4 alco-hol, styrene, a C1 to CQ alkyl acrylate or methacrylate, and acrylonitri]e or methacrylonitrile in weight ranges ox frorn about 1 to about 25 parts hy weight of I] to O
monoalkyl maleate or umarate, from about 2~ to about ~R~
parts by weight of styrene, from about Jo about 7~
parts by weight of acrylate or methacrylate and from about to about US parts by weight of the acrylonitrile, based on l parts by weiqht of polymer shell.
The multiphase core//shell polymers are prepare by emulsion polymerization of the shell comonomers in the presence of an emulsion of the elastomer core by known techniques which favor the formation of rigid thermoplas-tic polymer shell around the elastomer core rather thandiscrete particles of rigid polymer separate from the core. The emulsion polymerization of the shell comono-mers onto the elastomer core is preferably controlled to provide a deqree of polymerization SUC'.1 that the apparent melt viscosity of the core//shell polymer determined, at a temperature 10C above the melting point of the poly-amide with which it is to be blended and at a shear raze of l sec. ], on polymer which has teen coagulate from the emulsion and tried, is no more than about ten times the apparent melt viscosity of the polyamide ancl is preferably in the range of one to eight tires the appa-rent melt viscosity of the polyamide. For nylon com-positions, the temperature for determination of apparent melt viscosity is 2~ C. The degree of polymerization can be conveniently controlled by addition of an appro-priate amount Oe a chain transfer agent such as a mer-captan, a polyhalogen compound or an allylic compound.
The elastomer core emulsion is preferably of weiqht average particle c'iameter of ~.3 micron or more and the thickness of the rigi~l polymer shell calculated from the weight added to the above elastomer, is preferably at least about 5 micron to prevent sintering of the core//shell particles upon coagulation and drying, and to facilitate form3tion of a uniform dispersion of the ` ,,, core/~shell polymer in the polyamide. More preferably the particle diameter is in the range of about ~.3 to about ~.~ micron and even more preferably it is in the range of about 0.4 to about 0.7 micron so that the proportion of rigid polymer shell necessary to prevent agglomeration and sintering of the emulsion particles during the coagulation and drying step is minimized.
when the elastomer core comprises a butadiene polymer or an acrylic polymer prepared by emulsion polymeric tion, the particle size is generally in the range of about l to about ~.2 micron. Seeding techniques can provide emulsions of larger particle size. However, since emulsion polymerization conditions which favor the ormation of large particle size, may cause a significant degree of coagulation of the elastomer core causing kettle fouling and detracting from the formation of fine, uniform dispersions of the multiphase core//shell polymer in the polyamide, it is generally preferred to form buta-diene and acrylic elastomer core emulsions of large par-ticle size in the range of about 0.3 to about ~.8 micron by controlled agglomeration of emulsions of 0.1 to 0.2 micron particle size. Aqglomeration may be achieved by any conventional means such as by the addition of a suit-able amount of water-soluble, carboxylic acid or anhy-dride of such acid. The agglomerated emulsicn is then stabilized by addition of a suitable emulsifier.
The amount of elastomer core in the multiphase core//
shell polymer may range from about 50 to about 90 parts by weight with about 19 to about 5n parts by weigh o riqid polymer shell applied thereto. More preferably, the amount of elastomer core is in the range of about ~0 to about ~0 parts by weight and the amount of rigid polymer shell is in the range of about 20 to about 4 parts by weight.
Polymerization of the rigicl polymer shell is carried out under conditions which favor polymerization at or onto the surface of the elastomer core emulsion so that no substantial number of new "seeds" or particles form in the emulsion. This is generally accomplished by con-.
'7 trolling the rate of addition of monomer, emulsifier and initiator. Preferably no further emulsifïer is added after formation of the core elastomer emulsion. When polymerization is substantially complete, the multiphase core//shell polymer is coagulated by any convenient method such as by freezing, by addition of a coagulating solvent such as methanol optionally containing a small amount of strong acid such as hydrochloric acid, or by addition of an aqueous solution of a polyvalent metal salt such as magnesium sulfate or aluminum sulfate. The coagulated emulsion is washed thoroughly with water to remove emulsifiers and salts and dried preferably at a temperature at least 1~C below the glass transition temperature of the rigid polymer shell.
81ends of polyamide and multiphase core//shell polymer can be pFepared by melt blending in a closed system at a temperature in the range of about 5 to about 10~C above the melting point of the polyamide. Single or double screw extruders may be conveniently used for the blending process Advantages of the present compo-sitions lie in the ease with which they are blended with polyamides in a single screw extruder and the ease with which uniform submicron dispersions of the multiphase core//shell polymer in the polyamide are formed. It is believed that such effects can only be achievecl if the latex particles obtained after graft polymerization of the rigid shell onto the elastomer core, are able to preserve their shape and size when redispersed in the polyamide by melt blending. For this to be achieved, the polymer crumb obtained my coagulation of the latex, should be able to break up into particles of essentially the same size and shape as the particles of the grafted latex. In other words, the crumb after drying must have sufficiently loose clusters to permit redispersion and this looseness is promoted by the rigid polymer shell which prevents the particles of elastomer from sintering into a solid mass.
The improvement in toughness of polyamides when they are blended with the multiphase core//shell polymers of 22'7 the present invention in comparison with unblended polyamide is manifested by a higher notched Izod value and reduction in the percentage of brittle failure in a multiaxial driven dart test. The Izod value increases steadily with increase in the amount of elastomer core material in the polyamide blend and is in the range of
15Patent 3,~8,274 teaches modestly improved impact strength of polyamides modified with (A) a first cross-linked elastomer phase of copolymers or terpolymers and (B) a final rigid phase thermoplastic stage containing amine-reactive moieties, preferably carboxylic acid groups. The soft modifier is coated with a rigid layer thus apparently negating a large improvement in polyamide toughness Dunkelberger, U.~. Patent 4,167,5~5, recognizes that the polymer modifiers of Owens et al impart improvement in the impact strength of higher molecular weight posy-,~., amides but that the resulting blends do not exhibit the good flow necessary for injection molding operations and teaches that Owens' core//shell polymers having high rubber core content are not capable of being admixed and dispersed in low molecular weight nylon due to the very low viscosity of nylon above the melting point and the resulting difficulty of dispersing a viscous component in a fluid medium due to insufficient shear.
Another approach to the problem o enhancing the toughness of polyamides is provided by Epstein, U.S.
Patent 4,17A,358. Toughened multiphase polyamides were obtained by incorporating elastomers modified by copoly-merization or reaction with monomers containing func tional groups such as carboxy groups capable of reaction or hydrogen-bonding with polyamides. This approach has been used with acrylates, polyethylenes, ethylene propy-lene rubbers, ethylene propylene diene rubbers and ethy-lene vinyl acetate copolymers. The resulting function-alized bulk rubbers or elastomers require very intensive20 shear in order to be finely dispersed in a polyamide matrix. The rubbers must, therefore, be soluble (i.e., not crosslinked) in order to permit flow and dispersion on heating. Since the rubber particles are soluble and deEormable, their final size is largely dependent on intensity o shear on extrusion and molding. The desired fine rubber dispersions are difficult to obtain without intensive shear, and control of rubber particle si2e in the final molding is not easily obtained.
Humme et al, U.S. Patent ~,221,~79, discloses impact-resistant polyamides consisting substantially of a poly-amide and a graft product of a polybutadiene as a graft substrate and a mixture of an acrylate or methacrylate, and acrylonitrile and/or acrylamide monomers grafted thereon. The grafted shell is generally elastomeric in nature. 5ra,t products containing a rigid shell such as a styrene copolymer shell are found to be unsatisfactory apparently because of poor compatibility with the poly-amide.
~89~7 SUMMARY OF THE INVENTION
According to one embodiment o:E this invention, there is provided a multiphase core//shell polymer comprising about 50 to about 90 pa.rts by weight oE a cross-linked elastomer core and about 10 to about 50 parts by weight of a rigid thermoplas-tic polymer shell of glass transition temperature at least about 35C., comprising from about 1 to about 25 parts by weight of an interpolymerized Cl to C4 monoalkyl maleate or fumarate, from about 20 to about 80 parts by weight oE inter-polymerized styrene, from about 0 to about 79 pa.rts by weight of an .interpolymerized Cl to C8 alkyl acrylate or methacry-late and rom about 0 to about 45 parts by weight of interpoly-merized acrylonitrile or methacrylonitrile based on 100 parts by weight of shell interpolymer, wherein the multiphase core//shell polymer has a core of weight average particle dia-meter of at least about 0.3 micron and a rigid shell of average thickness of at least about 0.025 micron.
The multiphase core//shell polymers are used for toughening polyamidesO
In accordance with another embodiment of this inven-tion, there is provided a process of preparing a multiphase core//shell polymer which comprises preparing an aqueous emul-sion of an elastomeric core polymer oE weight average particle size in the range oE at least about 0.3 micron; graft polymeriz-ing on the elastomeric core a rigid shell comprising from about l to about 25 parts by weight of an interpolymerized Cl to O monoalkyl maleate or fuma.rate~ from about 20 to about 80 parts by weight of interpolymerized styrene, from about 0 to about 79 parts by weight oE an interpolymerized Cl to O
alkyl acrylate or methacrylate and from about 0 to about 45 parts by weight of interpolymerized acryloni-trile or methacrylo-.~
2~7 - 3a -nitrile per 100 parts by weight of shell interpolymer, wherein the rigid shell has a glass transition temperature of at least 35C. and is of average thickness at least about 0.025 micron and wherein the weight ratio of core to shell is in the range oE about 9:1 to about 1:1; and recovering the multiphase core//shell polymer from the aqueous emulsion.
DETAILED DESCRIPTION OF THE INVENTION
The polyamide resins which are toughened by the multiphase core//shell compositions of this inven-tion, are well known in the art and embrace those semi-crystalline and amorphous resins having a number average molecular weight in the range of about 5000 to 30,000 commonly referred to as nylons. PreEerably the molecu-lar weight is in the range oE about 8,000 to 20,000.
Suitable polyamides include -those described in U. S.
Pat. NosO 2,071,250; 2,071,251; 2,130,523; 2,130,948;
2,241,322; 2,312,966; 2,512, 606; and 3,393,210. The polyamide resin can be produced by condensa-tion of equi-molar amounts of a saturated dicarboxylic acid contain-ing from 4 to 12 carbon atoms with a diamine, in which the diamine contains Erom 4 to 14 carbon atoms. Excess diamine can be employed to provide an excess of amine end groups over carboxyl end groups in -the polyamide.
Examples oE polyamides include polyhexamethylene adipamide ~66 nylon), polyhexamethylene azelamide (69 nylon), polyhexamethylene sebacamide (610 nylon), polyhexamethylene dodecanoamide ,, .~
(612 nylon) and bis (paraaminocyclohexyl) methane dodeca-noamide. The polyamide resin can also be produced by ring opening of lactams, for example polycaprolactam and polylauric lactam, and by condensation of -amino-car-S boxylic acids, for example, poly-ll-aminoundecanoic acid.
It is also possible to use in this invention polyamides prepared by the copolymerization of two of the above polymers or terpolymerization of the above polymers or their components, e.g~, for example, an adipic, iso-phthalic acid hexamethylene diamine copolymer. Prefer-ably the polyamides are linear with a melting point in excess of 2~C. As yreat as 99 percent by weight of the composition can be composed of polyamide; however, pre-ferred compositions contain from 55 to 99 percent, and more narrowly ~5 to 90 percent, by weight of polyamide.
The molecular weight of the polyamide is selected in the range of 5000 to 3~,00~ number average, preferably 80~0 to 2~,~0~ to provide polyamide compositions which can be readily molded by injection or extrusion tech-niques The multiphase core//shell polymer of the present invention is an elastomer based composite interpolymer material having a crosslinked elastomer core and a rigid thermoplastic polymer shell.
The elastomer core can be a tone elastomer, an ethylene-propylene-diene rubber, an acrylic e]stomer, or a polyurethane elastomer. The diene elastomers include polybutadiene, polyisoprene, polychloroprene and poly-(cyanobutadiene~. The diene may be copolymerized with up to about 50 weight percent of other monomers such as alkyl acrylates and methacrylates, styrene, -methyl-styrene, acrylonitrile and substituted acrylonitriles, vinyl ethers, vinyl amides, vinyl esters and the like.
The acrylic elastomers comprise 5~ to 99O9 parts by weight ox an alkyl acrylate containing 1 to l carbon atoms, preferably 2 to carbon atoms, 0 to 4~ parts by weight of other ethylenically unsaturated monomers and .1 to 5 parts by weight of a polyunsaturated cross-linking monomer such as polyacrylic and polymethacrylic 2'7 -5- C-08~12-1182 esters of polyols such 3S butylene diacrylate and di~eth-acrylate, trimethylolpropane trimethacrylate and tne like, vinyl acrylate and methacrylate, divinyl and tri-vinyl benzene and the like. Optionally from about 001 to5 about 5 parts by weight o a graft-linking monomer with two or more addition polymerizable unsaturated groups which participate in polymerization at different rates, may also be included. It is preferred that the graft-linking monomer has at least one reactive group which polymerizes at about the same rate, or slightly slower than the other monomers, while the remainirlg reactive group or groups polymerize at a substantially slower rate. The differential polymerization rates result in a residual level of unsaturation in the elastomer core, particularly during the latter stages of polymerization and, consequently, at or near the surface of the elasto-mer particles. When the rigid thermoplastic shell is subsequently polymerized at the surface of the elastomer, the residual unsaturated addition-polymerizable reactive groups contributed by the graft-linking monomer partici-pate in the subsequent reaction so that at least a por-tion of the rigid shell is chemically attached to the surface of the elastomer. The crosslinked elastomer core preferably has a glass transition temperature below about -25C and a swelling index ranging from about 2 to about 20 determined in a good "solvent" for the elastomer, i.e.
a solvent which has a solubility parameter close to the solubility parameter of the polymer and is similar in polarity and hydrogen-bonding ability. Thus for poly-butadienes, suitable solvents for determination ofswelling index include benzene, to]uene and tetrahydro-furan and for acrylic elastomers, suitable solvents include acetone, benzene and toluene.
The elastomeric core is prepared in bulk, in emulsion or in solution. Those prepared in bulk or solution are converted into aqueous emulsion by known techniques prior to the addition polymerization of -the rigid polymer shell thereto.
The rigid thermoplastic polymer shell has a glass '7 -6- C-08~12-1182 transition temperature of at least ahout 35 C ~n~ com-prises a monomaleate or monofumarate of a Cl to C4 alco-hol, styrene, a C1 to CQ alkyl acrylate or methacrylate, and acrylonitri]e or methacrylonitrile in weight ranges ox frorn about 1 to about 25 parts hy weight of I] to O
monoalkyl maleate or umarate, from about 2~ to about ~R~
parts by weight of styrene, from about Jo about 7~
parts by weight of acrylate or methacrylate and from about to about US parts by weight of the acrylonitrile, based on l parts by weiqht of polymer shell.
The multiphase core//shell polymers are prepare by emulsion polymerization of the shell comonomers in the presence of an emulsion of the elastomer core by known techniques which favor the formation of rigid thermoplas-tic polymer shell around the elastomer core rather thandiscrete particles of rigid polymer separate from the core. The emulsion polymerization of the shell comono-mers onto the elastomer core is preferably controlled to provide a deqree of polymerization SUC'.1 that the apparent melt viscosity of the core//shell polymer determined, at a temperature 10C above the melting point of the poly-amide with which it is to be blended and at a shear raze of l sec. ], on polymer which has teen coagulate from the emulsion and tried, is no more than about ten times the apparent melt viscosity of the polyamide ancl is preferably in the range of one to eight tires the appa-rent melt viscosity of the polyamide. For nylon com-positions, the temperature for determination of apparent melt viscosity is 2~ C. The degree of polymerization can be conveniently controlled by addition of an appro-priate amount Oe a chain transfer agent such as a mer-captan, a polyhalogen compound or an allylic compound.
The elastomer core emulsion is preferably of weiqht average particle c'iameter of ~.3 micron or more and the thickness of the rigi~l polymer shell calculated from the weight added to the above elastomer, is preferably at least about 5 micron to prevent sintering of the core//shell particles upon coagulation and drying, and to facilitate form3tion of a uniform dispersion of the ` ,,, core/~shell polymer in the polyamide. More preferably the particle diameter is in the range of about ~.3 to about ~.~ micron and even more preferably it is in the range of about 0.4 to about 0.7 micron so that the proportion of rigid polymer shell necessary to prevent agglomeration and sintering of the emulsion particles during the coagulation and drying step is minimized.
when the elastomer core comprises a butadiene polymer or an acrylic polymer prepared by emulsion polymeric tion, the particle size is generally in the range of about l to about ~.2 micron. Seeding techniques can provide emulsions of larger particle size. However, since emulsion polymerization conditions which favor the ormation of large particle size, may cause a significant degree of coagulation of the elastomer core causing kettle fouling and detracting from the formation of fine, uniform dispersions of the multiphase core//shell polymer in the polyamide, it is generally preferred to form buta-diene and acrylic elastomer core emulsions of large par-ticle size in the range of about 0.3 to about ~.8 micron by controlled agglomeration of emulsions of 0.1 to 0.2 micron particle size. Aqglomeration may be achieved by any conventional means such as by the addition of a suit-able amount of water-soluble, carboxylic acid or anhy-dride of such acid. The agglomerated emulsicn is then stabilized by addition of a suitable emulsifier.
The amount of elastomer core in the multiphase core//
shell polymer may range from about 50 to about 90 parts by weight with about 19 to about 5n parts by weigh o riqid polymer shell applied thereto. More preferably, the amount of elastomer core is in the range of about ~0 to about ~0 parts by weight and the amount of rigid polymer shell is in the range of about 20 to about 4 parts by weight.
Polymerization of the rigicl polymer shell is carried out under conditions which favor polymerization at or onto the surface of the elastomer core emulsion so that no substantial number of new "seeds" or particles form in the emulsion. This is generally accomplished by con-.
'7 trolling the rate of addition of monomer, emulsifier and initiator. Preferably no further emulsifïer is added after formation of the core elastomer emulsion. When polymerization is substantially complete, the multiphase core//shell polymer is coagulated by any convenient method such as by freezing, by addition of a coagulating solvent such as methanol optionally containing a small amount of strong acid such as hydrochloric acid, or by addition of an aqueous solution of a polyvalent metal salt such as magnesium sulfate or aluminum sulfate. The coagulated emulsion is washed thoroughly with water to remove emulsifiers and salts and dried preferably at a temperature at least 1~C below the glass transition temperature of the rigid polymer shell.
81ends of polyamide and multiphase core//shell polymer can be pFepared by melt blending in a closed system at a temperature in the range of about 5 to about 10~C above the melting point of the polyamide. Single or double screw extruders may be conveniently used for the blending process Advantages of the present compo-sitions lie in the ease with which they are blended with polyamides in a single screw extruder and the ease with which uniform submicron dispersions of the multiphase core//shell polymer in the polyamide are formed. It is believed that such effects can only be achievecl if the latex particles obtained after graft polymerization of the rigid shell onto the elastomer core, are able to preserve their shape and size when redispersed in the polyamide by melt blending. For this to be achieved, the polymer crumb obtained my coagulation of the latex, should be able to break up into particles of essentially the same size and shape as the particles of the grafted latex. In other words, the crumb after drying must have sufficiently loose clusters to permit redispersion and this looseness is promoted by the rigid polymer shell which prevents the particles of elastomer from sintering into a solid mass.
The improvement in toughness of polyamides when they are blended with the multiphase core//shell polymers of 22'7 the present invention in comparison with unblended polyamide is manifested by a higher notched Izod value and reduction in the percentage of brittle failure in a multiaxial driven dart test. The Izod value increases steadily with increase in the amount of elastomer core material in the polyamide blend and is in the range of
3~ to l J/m notch when the elastomer content is in the range of 12-18 weight percent of the composition.
Thus values of 500 J/m notch are readily obtained. Quite modest concentrations of elastomer reduce the percentage of brittle failure of the polyamide in the multiaxial driven dart test and when the elastomer content is l by weight or more the percentage is reduced to I. A con-siderable irnprovement in notched impact strength at low temperatures such as -40C and lower is also observedO
The blends of multiphase core//shell polymer and polyamide may be modified by one or more conventional additives such as stabilizers and inhibitors of oxida-tive, thermal, and ultraviolet light degradation, lubri-cants and mold release agents, colorants, nucleating agents and plasticizers. Up to 5~ weight percent of glass fiber or fibrous and particulate inorganic fillers can increase the modulus and resistance to heat distor-tion of the blends by a substantial degree.
The stabilizers can be incorporated into the blends at any stage in their preparation. Preferably the stabilizers are included early to preclude the initiation of degradation. Such stabilizers must be compatible with the blend. The oxidative and thermal stabilizers useful in the blends include those used in polyamides, elas-tomers, and addition polymers generally. They inclucle, for example, Group I metal halides, e.g., sodium, potassium and lithium, with cuprous halides, e.g., chloride, bromide, iodide, and also hindered phenols, hydroquinones, phosphites and varieties of substituted members of those groups and combinations thereof. Ultra-violet light stabilizers, can include various substituted resorcinols, salicylates, benzotriazoles, benzophenones, and the like.
,2~
-10- C-08-12~ 2 Suitable lubricants and mold release agents, are stearic acid, stearic alcohol, stearamides; organic dyes include nigrosine, etc.; suitable pigments include ti-tanium dioxide, cadmium sulfide, cadmium sulfide sele-nide, phthalocyanines, ultramarine blue, carbon black, etc.; suitable fibrous and particulate fillers and rein-forcements include carbon fibers, glass fibers, amorphous silica, asbestos, calcium silicate, aluminum silicate, magnesium carbonate, kaolin, chalk, powderd quartz, mica, feldspar, etc,; nucleating agents include talc, calcium fluoride, sodium phenyl phosphinate, alumina, and finely divided polytetrafluoroethylene, etch; plasticizers, ùp to about 2a percent, based on the weight of the polyamide blend, include dioctyl phthalate, dibenzyl phthalate, butyl benzyl phthalate, hydrocarbon oils, N-normal butyl benzenesulfonamide, N-ethyl ortho- and para-toluene-sulfonamide, etc.
The toughened polyamide blends can be made into a wide range of useful articles by conventional molding methods employed in the fabrication of thermoplastic articles, i,e., as molded parts and extruded shapes, such as tubing, films, sheets, fibers and oriented .ibers, laminates and wire coating.
EXAMPLES OF THE INVENTION
The following examples illustrate the invention wherein parts and percentages are by weight unless otherwise indicated.
PREPARATION OF ELASTOMER CORE POLYMERS
A polybutadiene latex is produced by polymerizing butadiene at 70C to 9~ percent conversion with a redox initiator. The latex has a solids content of ~2~ and a weight average particle size of 0013 microns. To 20 parts by weight of the latex, there is rapidly added l.l part by weight of acetic anhydride mixed with 6~ parts by weight of crushed ice, and the latex is stirred vigo-rously for about 15 seconds and allowed to stand undis-turbed for 30 minutes. The agglomerated latex is then stabilized by slow and careful addition of 2 parts by weight of a mixture of mono- and di-phosphate esters of an alkylphenoxy polyethylene glycol containing about 9 ethylene oxide units per glycol molecule sold under the name GafacR alp by GAF Corporation. The emulsifier is added as a lo percent aqueous solution adjusted to a pH
of 12 by addition of sodium hydroxide solution. The agglomerated latex is stirred gently to distribute the surfactant uniformly on it. The agglomerated latex contains 29 percent rubber solids. The weight averge particle size of the agglomerated latex is ~.5 micron.
Similarly, agglomerated polybutadiene latices with 0.29, ~.~ and ~.6~ micron weight average particle sizes are prepared by adding ~.5, 0~8 and 1.2 parts of acetic anhydride t4 2~0 parts by weight of polybutadiene latex.
PREPARATIOM OF MULTIPHASE CORE//SHELL POLYMERS
Agglomerated latex containing l parts by weight of polybutadiene of 0.5 micron weight average particle size is charged to a reaction kettle fitted with a temperature controller, two calibrated holding tanks (for monomer and persulfate solution additions), a baffle; a Teflon bladed agitator, and a condenser, and is diluted to about 2~
solids with water. The batch is purged by bubbling nitrogen into it through a sparger Eor about 15-2~
minutes while the batch is gently stirred and brouqht to 8~C
A monomer mixture containing 3~ parts by weight styrene 18 parts by weight acry]onitrile, 3 parts by weight monoethyl maleate and ~.75 parts by weight of terpinolene and an aqueous solution of potassium persul-fate containing ~.9~ parts of persulfate in 35 parts by weight of water, are prepared.
The monomer mixture and the persulfate solution are charged to the holding tanks and are also purged by bubbling nitrogen for about 5-1~ minutes. A nitrogen atmosphere is maintained in the kettle and tanks through-out the course of polymerization.
When the kettle contents reach 8~C, about 1~-15~ of the monomer and initiator charge is added to the batch.
The batch is stirred for about 15 minutes. At the end of this time, the continuous addition of the streams of * Trademark I., 9~7 monomer and catalyst is started. The rate of addition of the two streams is adjusted to complete the addition in about 4 hours. Polymerization at Q~C is then continued for an additional hour. Monomer conversion is 95 per-cent. At the end of polymerization, the batch isfiltered through cheesecloth. In general very little coagulum is obtained despite the fact that no additional emulsifier is charged during the course of polymeriza-tion. To the filtered latex is added an aqueous emulsion containing 25% by weight of mixed alkylated aryl phos-phites sold by Uniroyal Corp. under the tradename PolygardR and 12.5~ by weight of 2,5-di-t-butyl-4-methyl-phenol sold by Shell Chemical Corp. under the trademark "Ionol." The amount added is designed to give 2 parts Polygard and 1 part Ionol per l parts of polybutadiene charged The resulting stabilize latex is coagulated by adding it to a 3% aqueous solution of magnesium sulfate hexahydrate at ~5-98C. A ratio of 2-3 volumes of ma-gnesium sulfate solution for 1 volume of latex is used.
The coayulated material is washed several times on a filter with cold, filtered water. Most of the water is removed by vacuum filtration or by centrifugation. The remaining water is removed at ~(I-7~C in a vacuum oven.
Drying is continued until no sign of rnoisture can be detected in a dry ice/acetone trap.
The ratio of elastomer core to rigid shell is lo The grafting efficiency is 2~ percent. The intrinsic viscosity of the soluble raction of the rigid shell is ~.32. The apparent melt viscosity of the multiphase polymer is 5.R k-poise at 26~C and a shear rate of 1~3 sec. 1. The example is designated Example I in Table 1.
The apparent melt viscosity of polyamide 1 of table 2 under the same conditions is 1.5 k-poise.
Similarly by selection of polybutadiene latices of appropriate particle size, multiphase core//shell poly-mers of different core: shell ratios and different rigid polymer shell composition are prepared by the same pro-cess.
9~
O
q,I,................
CO
I, .
.
f o En H
Us 0 ~4 I I I t I I I I I I Ln row .
r,q l or; o n Ln Ln F~ Fd n n U n Lo n I rn f I I Ln Al on pi z o o o o o o o o o o o o o o o o o o o o . ~Ul 1~1 ! us n n Ln n m n Ln n f Ln o us Ln Ln l l O o O JO f LD JO JO JO ED Ln Us ED
a Al I
pi o ED O co n co Lo Ln Lo Jo Us O O l nl I C) O l 0 l o o o o Al o o o o o I;
a p:;
H Us I' I` I` I`
a z Ln Ln Ln Ln Ln Ln .~
o n Ln Ln In n f . . . . . . . . . .
o o o o o o o o o o O H
C,) l H
H H H H
~4 H H H !-1 H H H H X
I--I H H H H X H H !-1 H H
H H H H H X X X X X X X I: X X
2~t7 o o pa o m I I I
o o o o o o o I, a s i o o o o o x o op `~
H O -I
f H l D
O I I I I I I I I I f f O
, ,~2 f O I
l 0 Us O O O O O O O O O O O O
l f r-l r-i r-l r-l r-l f i n f r~l f I I I l` O O (I
f r-i O Ui I; ' 1' ox m ,~
:; I i .,,, I .. I, n z o o o o o o o o o o a r-/ l I! . I R
o on o o o a o o o o o o o o o o f ,~, on ED U- JO W Rio ~7 JO JO ED Us f i l r-i ill U2 1 l 1.) r-l rl, a) >1 ~1H O h E-l O
I--i 0 r~3 us us o u7 us u7 us us ED us u7 us ul r Jo ED l I, O O O O O O O O O O O O o o o l ~i-IJ
r-i r-i f I f n r; f f r-i r I r; r; f i r; f l H 11 o rLi a) C) 3 Lo `
. , f E-l o H
H Ul 0 u7 U7 f 7 f f r ul us Us ul us u7 us us 0,~:
rr~i O O ,j O O O O O O O O O O O O O c, o o a f O
a H a) I) H H HH )~ a) H H H 1--1 H H l 1 X
I H H I> H H H X H H H H H ,~
Pi H H H H 1--I X X X X X X X X X .¢
X X X X X X X X X O X X X X X X li I, X x O X O x X X X X X
GRAFTING EFFICIENCY OF MULTIP~ASE CORE//SHELL POLYMER
The grafting efficiency is determined by extracting from the polybutadiene graft the shell polymer which is not chemically attached or grafted thereto.
A portion of the latex obtained at the end of grafting (prior to the addition of the stabilizers) is coagulated in a large excess of acidulated methanol. The coagulum is washed several times with methanol on the filter and then dried at 60C. The dry material is then pressed into a solid sheet in a mold heated to about 15~C (Note: compression of the crumb into a sheet is needed in order to avoid colloidal dispersion of the rubber on extraction with acetone.) The compressed sheet is cut into strips. A carefully determined weight of material (about 2 grams) is then placed in about 50 ml. of acetone for about ~8-20 hrs.
The clear acetone solution is syringed off and collected.
This extraction operation is repeated once more and all the collected acetone solution is taken to dryness by solvent evaporation The dry weight of the acetone soluble material (i.eO, that portion of the shell polymer which is not grafted to the polybutadiene core) is thus obtained.
Since the total amount of shell polymer is known, the amount of grafted shell polymer in the pre-weighed molded strips is computed. The grafting efficiency is the ratio of the weight of shell polymer not extracted with acetone to the total weight of shell polymer present in the sample.
Grafting Efficiency = W - We W
where W = the total weight of the shell in the sample and We = the weight of shell polymer extracted The grafting efficiency is generally in the range of about 20 to 4~ percent and increases with decreasing particle size of the polybutadiene core, decreasing ratio of shell to core and decreasing amount of chain transfer agent in the shell polymerization.
9~2~7 INTRINSIC VISCOSITY AND GLASS TRANSITION TEMPERATURE OF
THE_NON-GRAFTED PORTION OF MULTIPHASE CORE//SHELL POLYMER
Extraction of the shell polymer is conducted with DMF. The crumb obtained by coagulation with MgSOq is dried and molded into a sheet as described above. Strips are then leached in DMF; the solution, filtered through glass filter paper, is precipitated into acidulated 8~
methanol/20 water. The precipitate is filtered, washed with methanol/water, and dried.
The intrinsic viscosity of the non-gra~ted shell polymer is determined in DMF at 25C.
The glass transition temperature is determined on a duPont Differential Scanning Calorimeter, Model No. 90~
with a sample size of about 0.1 to about 0.2g. The heating rate is 2~C per minute. The Tg is the mid-point of the glass transition deflection.
PREPARATION OF POLYAMIDE BLENDS
_ Blend components are carefully dried before extrusion. The polyamide in pellet form is dried at about 80C overnight at a pressure less than 1 torr.
The multiphase core//shell polymer dried separately, is then mixed with the polyamide pellets by tumbling in a dry vessel at a temperature about 1~C. below the glass transition temperature of the rigid polymer shell and stored in sealed containers ready for use.
A single stage 2.54 cm. ~illion*extruder with a 2 stage (vent plugged)~24:1 screw at a screw speed of 100 rpm. is used for melt blending. A 40 mesh screen with a breaker plate is used at the nozzle of the extruder. For nylon 6,6 the set temperature profile for the various zones, from hopper to nozzle, is generally the following:
285, 282, 277, 266, 266C.
The dry blend is charged to a nitrogen purged hopper and maintained under nitrogen during the course of extru-sionO The extrudate is passed through a short section ofwater, through a stream of air and ground hot into a jar purged with nitrogen.
The extrudate is dried in vacuo at about 70C over-nightO A second pass extrusion is then conducted The * Trademark ~9~'7 extrudate, following this second pass, is again dried overnight at 70C in vacuo before molding.
A slightly rough extrudate is often obtained in the first extrusion, possibly due to uneven distribution of the bulky rubber in the hopper and/or incompletely dis-persed rubber. A smooth extrudate is generally obtained on the second extrusion.
Molding of Blends Injection molding is conducted in a 1/2 oz. Arburg lO machine. Typical molding conditions used for nylon 6,6 blends are:
Bottom Nozzle Mold Injection Pressure 90-120 kPa Fill Time 2-4 Seconds Hold Time 15 Seconds Total Cycle 30-45 Seconds Screw Speed 250-350 RPM
Apparent melt viscosity of polyamide and core//shell polymer The apparent melt viscosity of the polyamide and multiphase core//shell polymer components of a polyblend composition are determined in a Sieglaff-McKelvey ~heometer with a capillary length to diameter ratio of 10:1, at a temperature 10C above the melting point of the polyamide.
Mechanical Properties of Polyblends .
Molded samples of the polyblends of polyamide and multiphase core//shell polymer are subjected to mech-anical testing in the "dry-as-moldedn state. The following tests are used:
notched Izod toughness: ASTM D-256-56 Tensile Strength: ASTM D-638-58T
Elongation: ASTM D-638-58T
Tensile Modulus of the polymers: ASTM D-882 Particle Size: electron micrographs of micro-tomed molded specimens Multiaxial Driven Dart Test is performed with a dart of 6.35 mm. diameter and a hemispherical head driven I; * Trademark i at a rate of 112 meters per minute.
The data for the polyblends are presented in Table 20 The matrix polyamides are nylon 6,~ and a nylon 6,6/nylon 6 copolymer in the ratio 85:l5, of number average molecu-lar weight 18000. These matrix polymers are designatedpolyamide 1 and polyamide 2 respectively in Table 2.
Examples 1-43 are within the scope of the invention.
Examples A-F are introduced for comparative purposes.
3ata for the polyamides show that the notched impact strength is quite low and that the impact resistance in the driven dart test is quite high, the frequency of brittle failure being significant, namely 10 percent.
When the polyamides are blended with butadiene//styrene core//shell polymer (example A), and butadiene//sty-rene/acrylonitrile core//shell polymer (examples B, C andD) at best a modest improvement in notched impact strength is obtained but the frequency of brittle failure in the driven dart test is increased. When a carboxy monomer is introduced into the shell of a butadiene//
styrene core//shell polymer some improvement in impact strength and reduction in brittle failure is observed (example E versus example A). Similarly with a core//
shell polymer containiny acid modified polymethyl Seth-acrylate as the shell polymer a minor improvement in impact strength is observed (example F). In contrast when the shell comprises a carboxy monomer and styrene and acrylonitrile or an acrylate or methacrylate monomer or acrylonitrile and an acrylate or methacrylate monomer siynificant improvement in notched impact strength and elimination of brittle failure in the driven dart test are observed (examples 1 to 43).
Examples 4-7 provide a series of blends containing core//shell polymers of decreasing polybutadiene content.
The notched impact strength decreases with decreasing butadiene content but in every case only ductile failure is observed in the driven dart test. The improvement in notched impact strength versus unblended polyamide is very pronounced when the butadiene content is above about 12 percent.
2~7 , o ox I, ._ o o o O .~ O I I CD. O O. O
_I
.~ c f _ O _ O Q O
o o o o o o o o o a o o a dP o _1 Jo f _1 ' u7 o f o _1 o r-" o o o o ~J O CO N Us U l O O ED O O O ~0 N l on CO N O
o e D O r1 tl'l it r1 N Ir Z H
Ll e cP
. r N ~3 0 0 0 0 tn l t O O Ox t a:l O CO tn N O N t tn tn tn tn CO 0~t 3~ I:d U U
top , .
u) a ~3S `
8~ tn tn JJ l OCl O O O O O O O O O O O O O O N f O 1~1 0 0 0 l 1"171 N to 7 N N N ~7 N rr~
U D
--I
l I H
H H H X
r1 Ll _I 1l~ . ' ' HX H I H l O O X X X X X X X H H H H HH Ho :~ H , H H >C H H
l 0 El X II N r-l N N _I N~1 H _I N N N N N N N N N H
rl o _I, r~l ..
a a aJ ''3 Y] U 2 tcl ~4 _I N or ln O --I N n X o o o ,, 0 ,1 ,r l r~l I I I I I I I I I I I I I I I I I
. _ .
C UP
o 0 f N
r r~l C
I: 0 O CO CO I I I I I I I I I I I I
-f 4 u7 l _l O N o V
C,l V O
Jo C4 En cn l Cn O O In Jo f l O Co 1-- Co cn CO O l l 1-- 0 f o Jo f 37 H r cc. Co cn co cn f rn cn E3 dP
I¦ o o m Co m O a cn O O cn o O O O
v Ci 1 ,r~l ,1 N .-1 Cal N N to 1 f ' N
CJ.~ P
.~ o o o o In o o o us us o n o o Ul o us o o , O O
;J
no S
Jo H~IH ~HH~ ~1~1 HH~XXXXXXXXXXXXX
~C~Pl XXXXXXXXXXXXXXXXXXXX
O
~NNNNNNNNNNNNNNNNN
0~~
. I ' o C) ~cnO~N~O~Cocno~ N
_ ~NNNNNNr~ N NN~
X
o o o up Al s N al f , , , , , , , I, N
. I
O N I I
.
.C r Z
E f o _~ l o us N O
h TV
Ul _ r-l O O r O f r O O O O
,1 u, al al us o us o o o o o o O
u ray U) f ,r rl E W H
. X X I H
X X X XX X X X
I: u f x x I: x x x x x o l N N N N N N N N
-I h r cn o N
2t7 Examples 8-13 illustrate the effect of the ratio of-elastomer core to rigid shell and the advantage of having sufficient hard shell around the soft core to protect the core and permit formation of a dispersion of the coagu-lated core//shell polymer with particles of size compar-able to the size of the original polybutadiene core.
Electron microscopy reveals that the polyblend of example 11 contains a uniform dispersion of particles of core shell polymer of a size (about 0.3 micron) similar to the size of the original agglomerated polybutadiene latex.
The polyblend has high impact strength When the amount of rigid shell protecting the polybutadiene is reduced in examples 9 and 10, electron microscopy shows that the dispersion in the polyamide is much less complete and mechanical tests show reduction in the impact strength with reduction in the amount of rigid shell. Even at a 1:1 core:shell ratio, multiphase core~/shell polymers prepared from polybutadiene latex of particle size 0.13 are not uniformly dispersed in polyamide, and the poly-blends have low impact strength. (examples 12, 13). In contrast although the elastomer content of example 8 is substantially lower than the elastomer content of ex-amples 12 and 13 the notched impact strength is substan-tially higher.
Example 14, 17 and 18 show that polyblends containing multiphase core//shell polymers in which acid monomers other than monoethyl maleate are incorporated into the rigid shell, also show improved toughness.
Examples 15~ 16 and 19 to 26 contain core//shell polymers with shells comprising various amounts of inter-polymerized acid monomer. The data suggest that an opti-mum acid concentration occurs in the range of about 5 to 15 weight percent corresponding to a concentration of carboxy groups in the range of about 1.6 to about 4.8 weight percent.
A further advantage of the core//shell modified poly-amide compositions resides in their high impact strengths at low temperaturesO Table 3 sets forth the data obtained at -4~C.
,2t7 Example Notched Impact IDI, J, -40C
, J/m notch at -40C
Polyamide 2 49 5 to 76 2~ 179 48 158 4~
2~ 2al 53 32 1~8 63 37 lay 19
Thus values of 500 J/m notch are readily obtained. Quite modest concentrations of elastomer reduce the percentage of brittle failure of the polyamide in the multiaxial driven dart test and when the elastomer content is l by weight or more the percentage is reduced to I. A con-siderable irnprovement in notched impact strength at low temperatures such as -40C and lower is also observedO
The blends of multiphase core//shell polymer and polyamide may be modified by one or more conventional additives such as stabilizers and inhibitors of oxida-tive, thermal, and ultraviolet light degradation, lubri-cants and mold release agents, colorants, nucleating agents and plasticizers. Up to 5~ weight percent of glass fiber or fibrous and particulate inorganic fillers can increase the modulus and resistance to heat distor-tion of the blends by a substantial degree.
The stabilizers can be incorporated into the blends at any stage in their preparation. Preferably the stabilizers are included early to preclude the initiation of degradation. Such stabilizers must be compatible with the blend. The oxidative and thermal stabilizers useful in the blends include those used in polyamides, elas-tomers, and addition polymers generally. They inclucle, for example, Group I metal halides, e.g., sodium, potassium and lithium, with cuprous halides, e.g., chloride, bromide, iodide, and also hindered phenols, hydroquinones, phosphites and varieties of substituted members of those groups and combinations thereof. Ultra-violet light stabilizers, can include various substituted resorcinols, salicylates, benzotriazoles, benzophenones, and the like.
,2~
-10- C-08-12~ 2 Suitable lubricants and mold release agents, are stearic acid, stearic alcohol, stearamides; organic dyes include nigrosine, etc.; suitable pigments include ti-tanium dioxide, cadmium sulfide, cadmium sulfide sele-nide, phthalocyanines, ultramarine blue, carbon black, etc.; suitable fibrous and particulate fillers and rein-forcements include carbon fibers, glass fibers, amorphous silica, asbestos, calcium silicate, aluminum silicate, magnesium carbonate, kaolin, chalk, powderd quartz, mica, feldspar, etc,; nucleating agents include talc, calcium fluoride, sodium phenyl phosphinate, alumina, and finely divided polytetrafluoroethylene, etch; plasticizers, ùp to about 2a percent, based on the weight of the polyamide blend, include dioctyl phthalate, dibenzyl phthalate, butyl benzyl phthalate, hydrocarbon oils, N-normal butyl benzenesulfonamide, N-ethyl ortho- and para-toluene-sulfonamide, etc.
The toughened polyamide blends can be made into a wide range of useful articles by conventional molding methods employed in the fabrication of thermoplastic articles, i,e., as molded parts and extruded shapes, such as tubing, films, sheets, fibers and oriented .ibers, laminates and wire coating.
EXAMPLES OF THE INVENTION
The following examples illustrate the invention wherein parts and percentages are by weight unless otherwise indicated.
PREPARATION OF ELASTOMER CORE POLYMERS
A polybutadiene latex is produced by polymerizing butadiene at 70C to 9~ percent conversion with a redox initiator. The latex has a solids content of ~2~ and a weight average particle size of 0013 microns. To 20 parts by weight of the latex, there is rapidly added l.l part by weight of acetic anhydride mixed with 6~ parts by weight of crushed ice, and the latex is stirred vigo-rously for about 15 seconds and allowed to stand undis-turbed for 30 minutes. The agglomerated latex is then stabilized by slow and careful addition of 2 parts by weight of a mixture of mono- and di-phosphate esters of an alkylphenoxy polyethylene glycol containing about 9 ethylene oxide units per glycol molecule sold under the name GafacR alp by GAF Corporation. The emulsifier is added as a lo percent aqueous solution adjusted to a pH
of 12 by addition of sodium hydroxide solution. The agglomerated latex is stirred gently to distribute the surfactant uniformly on it. The agglomerated latex contains 29 percent rubber solids. The weight averge particle size of the agglomerated latex is ~.5 micron.
Similarly, agglomerated polybutadiene latices with 0.29, ~.~ and ~.6~ micron weight average particle sizes are prepared by adding ~.5, 0~8 and 1.2 parts of acetic anhydride t4 2~0 parts by weight of polybutadiene latex.
PREPARATIOM OF MULTIPHASE CORE//SHELL POLYMERS
Agglomerated latex containing l parts by weight of polybutadiene of 0.5 micron weight average particle size is charged to a reaction kettle fitted with a temperature controller, two calibrated holding tanks (for monomer and persulfate solution additions), a baffle; a Teflon bladed agitator, and a condenser, and is diluted to about 2~
solids with water. The batch is purged by bubbling nitrogen into it through a sparger Eor about 15-2~
minutes while the batch is gently stirred and brouqht to 8~C
A monomer mixture containing 3~ parts by weight styrene 18 parts by weight acry]onitrile, 3 parts by weight monoethyl maleate and ~.75 parts by weight of terpinolene and an aqueous solution of potassium persul-fate containing ~.9~ parts of persulfate in 35 parts by weight of water, are prepared.
The monomer mixture and the persulfate solution are charged to the holding tanks and are also purged by bubbling nitrogen for about 5-1~ minutes. A nitrogen atmosphere is maintained in the kettle and tanks through-out the course of polymerization.
When the kettle contents reach 8~C, about 1~-15~ of the monomer and initiator charge is added to the batch.
The batch is stirred for about 15 minutes. At the end of this time, the continuous addition of the streams of * Trademark I., 9~7 monomer and catalyst is started. The rate of addition of the two streams is adjusted to complete the addition in about 4 hours. Polymerization at Q~C is then continued for an additional hour. Monomer conversion is 95 per-cent. At the end of polymerization, the batch isfiltered through cheesecloth. In general very little coagulum is obtained despite the fact that no additional emulsifier is charged during the course of polymeriza-tion. To the filtered latex is added an aqueous emulsion containing 25% by weight of mixed alkylated aryl phos-phites sold by Uniroyal Corp. under the tradename PolygardR and 12.5~ by weight of 2,5-di-t-butyl-4-methyl-phenol sold by Shell Chemical Corp. under the trademark "Ionol." The amount added is designed to give 2 parts Polygard and 1 part Ionol per l parts of polybutadiene charged The resulting stabilize latex is coagulated by adding it to a 3% aqueous solution of magnesium sulfate hexahydrate at ~5-98C. A ratio of 2-3 volumes of ma-gnesium sulfate solution for 1 volume of latex is used.
The coayulated material is washed several times on a filter with cold, filtered water. Most of the water is removed by vacuum filtration or by centrifugation. The remaining water is removed at ~(I-7~C in a vacuum oven.
Drying is continued until no sign of rnoisture can be detected in a dry ice/acetone trap.
The ratio of elastomer core to rigid shell is lo The grafting efficiency is 2~ percent. The intrinsic viscosity of the soluble raction of the rigid shell is ~.32. The apparent melt viscosity of the multiphase polymer is 5.R k-poise at 26~C and a shear rate of 1~3 sec. 1. The example is designated Example I in Table 1.
The apparent melt viscosity of polyamide 1 of table 2 under the same conditions is 1.5 k-poise.
Similarly by selection of polybutadiene latices of appropriate particle size, multiphase core//shell poly-mers of different core: shell ratios and different rigid polymer shell composition are prepared by the same pro-cess.
9~
O
q,I,................
CO
I, .
.
f o En H
Us 0 ~4 I I I t I I I I I I Ln row .
r,q l or; o n Ln Ln F~ Fd n n U n Lo n I rn f I I Ln Al on pi z o o o o o o o o o o o o o o o o o o o o . ~Ul 1~1 ! us n n Ln n m n Ln n f Ln o us Ln Ln l l O o O JO f LD JO JO JO ED Ln Us ED
a Al I
pi o ED O co n co Lo Ln Lo Jo Us O O l nl I C) O l 0 l o o o o Al o o o o o I;
a p:;
H Us I' I` I` I`
a z Ln Ln Ln Ln Ln Ln .~
o n Ln Ln In n f . . . . . . . . . .
o o o o o o o o o o O H
C,) l H
H H H H
~4 H H H !-1 H H H H X
I--I H H H H X H H !-1 H H
H H H H H X X X X X X X I: X X
2~t7 o o pa o m I I I
o o o o o o o I, a s i o o o o o x o op `~
H O -I
f H l D
O I I I I I I I I I f f O
, ,~2 f O I
l 0 Us O O O O O O O O O O O O
l f r-l r-i r-l r-l r-l f i n f r~l f I I I l` O O (I
f r-i O Ui I; ' 1' ox m ,~
:; I i .,,, I .. I, n z o o o o o o o o o o a r-/ l I! . I R
o on o o o a o o o o o o o o o o f ,~, on ED U- JO W Rio ~7 JO JO ED Us f i l r-i ill U2 1 l 1.) r-l rl, a) >1 ~1H O h E-l O
I--i 0 r~3 us us o u7 us u7 us us ED us u7 us ul r Jo ED l I, O O O O O O O O O O O O o o o l ~i-IJ
r-i r-i f I f n r; f f r-i r I r; r; f i r; f l H 11 o rLi a) C) 3 Lo `
. , f E-l o H
H Ul 0 u7 U7 f 7 f f r ul us Us ul us u7 us us 0,~:
rr~i O O ,j O O O O O O O O O O O O O c, o o a f O
a H a) I) H H HH )~ a) H H H 1--1 H H l 1 X
I H H I> H H H X H H H H H ,~
Pi H H H H 1--I X X X X X X X X X .¢
X X X X X X X X X O X X X X X X li I, X x O X O x X X X X X
GRAFTING EFFICIENCY OF MULTIP~ASE CORE//SHELL POLYMER
The grafting efficiency is determined by extracting from the polybutadiene graft the shell polymer which is not chemically attached or grafted thereto.
A portion of the latex obtained at the end of grafting (prior to the addition of the stabilizers) is coagulated in a large excess of acidulated methanol. The coagulum is washed several times with methanol on the filter and then dried at 60C. The dry material is then pressed into a solid sheet in a mold heated to about 15~C (Note: compression of the crumb into a sheet is needed in order to avoid colloidal dispersion of the rubber on extraction with acetone.) The compressed sheet is cut into strips. A carefully determined weight of material (about 2 grams) is then placed in about 50 ml. of acetone for about ~8-20 hrs.
The clear acetone solution is syringed off and collected.
This extraction operation is repeated once more and all the collected acetone solution is taken to dryness by solvent evaporation The dry weight of the acetone soluble material (i.eO, that portion of the shell polymer which is not grafted to the polybutadiene core) is thus obtained.
Since the total amount of shell polymer is known, the amount of grafted shell polymer in the pre-weighed molded strips is computed. The grafting efficiency is the ratio of the weight of shell polymer not extracted with acetone to the total weight of shell polymer present in the sample.
Grafting Efficiency = W - We W
where W = the total weight of the shell in the sample and We = the weight of shell polymer extracted The grafting efficiency is generally in the range of about 20 to 4~ percent and increases with decreasing particle size of the polybutadiene core, decreasing ratio of shell to core and decreasing amount of chain transfer agent in the shell polymerization.
9~2~7 INTRINSIC VISCOSITY AND GLASS TRANSITION TEMPERATURE OF
THE_NON-GRAFTED PORTION OF MULTIPHASE CORE//SHELL POLYMER
Extraction of the shell polymer is conducted with DMF. The crumb obtained by coagulation with MgSOq is dried and molded into a sheet as described above. Strips are then leached in DMF; the solution, filtered through glass filter paper, is precipitated into acidulated 8~
methanol/20 water. The precipitate is filtered, washed with methanol/water, and dried.
The intrinsic viscosity of the non-gra~ted shell polymer is determined in DMF at 25C.
The glass transition temperature is determined on a duPont Differential Scanning Calorimeter, Model No. 90~
with a sample size of about 0.1 to about 0.2g. The heating rate is 2~C per minute. The Tg is the mid-point of the glass transition deflection.
PREPARATION OF POLYAMIDE BLENDS
_ Blend components are carefully dried before extrusion. The polyamide in pellet form is dried at about 80C overnight at a pressure less than 1 torr.
The multiphase core//shell polymer dried separately, is then mixed with the polyamide pellets by tumbling in a dry vessel at a temperature about 1~C. below the glass transition temperature of the rigid polymer shell and stored in sealed containers ready for use.
A single stage 2.54 cm. ~illion*extruder with a 2 stage (vent plugged)~24:1 screw at a screw speed of 100 rpm. is used for melt blending. A 40 mesh screen with a breaker plate is used at the nozzle of the extruder. For nylon 6,6 the set temperature profile for the various zones, from hopper to nozzle, is generally the following:
285, 282, 277, 266, 266C.
The dry blend is charged to a nitrogen purged hopper and maintained under nitrogen during the course of extru-sionO The extrudate is passed through a short section ofwater, through a stream of air and ground hot into a jar purged with nitrogen.
The extrudate is dried in vacuo at about 70C over-nightO A second pass extrusion is then conducted The * Trademark ~9~'7 extrudate, following this second pass, is again dried overnight at 70C in vacuo before molding.
A slightly rough extrudate is often obtained in the first extrusion, possibly due to uneven distribution of the bulky rubber in the hopper and/or incompletely dis-persed rubber. A smooth extrudate is generally obtained on the second extrusion.
Molding of Blends Injection molding is conducted in a 1/2 oz. Arburg lO machine. Typical molding conditions used for nylon 6,6 blends are:
Bottom Nozzle Mold Injection Pressure 90-120 kPa Fill Time 2-4 Seconds Hold Time 15 Seconds Total Cycle 30-45 Seconds Screw Speed 250-350 RPM
Apparent melt viscosity of polyamide and core//shell polymer The apparent melt viscosity of the polyamide and multiphase core//shell polymer components of a polyblend composition are determined in a Sieglaff-McKelvey ~heometer with a capillary length to diameter ratio of 10:1, at a temperature 10C above the melting point of the polyamide.
Mechanical Properties of Polyblends .
Molded samples of the polyblends of polyamide and multiphase core//shell polymer are subjected to mech-anical testing in the "dry-as-moldedn state. The following tests are used:
notched Izod toughness: ASTM D-256-56 Tensile Strength: ASTM D-638-58T
Elongation: ASTM D-638-58T
Tensile Modulus of the polymers: ASTM D-882 Particle Size: electron micrographs of micro-tomed molded specimens Multiaxial Driven Dart Test is performed with a dart of 6.35 mm. diameter and a hemispherical head driven I; * Trademark i at a rate of 112 meters per minute.
The data for the polyblends are presented in Table 20 The matrix polyamides are nylon 6,~ and a nylon 6,6/nylon 6 copolymer in the ratio 85:l5, of number average molecu-lar weight 18000. These matrix polymers are designatedpolyamide 1 and polyamide 2 respectively in Table 2.
Examples 1-43 are within the scope of the invention.
Examples A-F are introduced for comparative purposes.
3ata for the polyamides show that the notched impact strength is quite low and that the impact resistance in the driven dart test is quite high, the frequency of brittle failure being significant, namely 10 percent.
When the polyamides are blended with butadiene//styrene core//shell polymer (example A), and butadiene//sty-rene/acrylonitrile core//shell polymer (examples B, C andD) at best a modest improvement in notched impact strength is obtained but the frequency of brittle failure in the driven dart test is increased. When a carboxy monomer is introduced into the shell of a butadiene//
styrene core//shell polymer some improvement in impact strength and reduction in brittle failure is observed (example E versus example A). Similarly with a core//
shell polymer containiny acid modified polymethyl Seth-acrylate as the shell polymer a minor improvement in impact strength is observed (example F). In contrast when the shell comprises a carboxy monomer and styrene and acrylonitrile or an acrylate or methacrylate monomer or acrylonitrile and an acrylate or methacrylate monomer siynificant improvement in notched impact strength and elimination of brittle failure in the driven dart test are observed (examples 1 to 43).
Examples 4-7 provide a series of blends containing core//shell polymers of decreasing polybutadiene content.
The notched impact strength decreases with decreasing butadiene content but in every case only ductile failure is observed in the driven dart test. The improvement in notched impact strength versus unblended polyamide is very pronounced when the butadiene content is above about 12 percent.
2~7 , o ox I, ._ o o o O .~ O I I CD. O O. O
_I
.~ c f _ O _ O Q O
o o o o o o o o o a o o a dP o _1 Jo f _1 ' u7 o f o _1 o r-" o o o o ~J O CO N Us U l O O ED O O O ~0 N l on CO N O
o e D O r1 tl'l it r1 N Ir Z H
Ll e cP
. r N ~3 0 0 0 0 tn l t O O Ox t a:l O CO tn N O N t tn tn tn tn CO 0~t 3~ I:d U U
top , .
u) a ~3S `
8~ tn tn JJ l OCl O O O O O O O O O O O O O O N f O 1~1 0 0 0 l 1"171 N to 7 N N N ~7 N rr~
U D
--I
l I H
H H H X
r1 Ll _I 1l~ . ' ' HX H I H l O O X X X X X X X H H H H HH Ho :~ H , H H >C H H
l 0 El X II N r-l N N _I N~1 H _I N N N N N N N N N H
rl o _I, r~l ..
a a aJ ''3 Y] U 2 tcl ~4 _I N or ln O --I N n X o o o ,, 0 ,1 ,r l r~l I I I I I I I I I I I I I I I I I
. _ .
C UP
o 0 f N
r r~l C
I: 0 O CO CO I I I I I I I I I I I I
-f 4 u7 l _l O N o V
C,l V O
Jo C4 En cn l Cn O O In Jo f l O Co 1-- Co cn CO O l l 1-- 0 f o Jo f 37 H r cc. Co cn co cn f rn cn E3 dP
I¦ o o m Co m O a cn O O cn o O O O
v Ci 1 ,r~l ,1 N .-1 Cal N N to 1 f ' N
CJ.~ P
.~ o o o o In o o o us us o n o o Ul o us o o , O O
;J
no S
Jo H~IH ~HH~ ~1~1 HH~XXXXXXXXXXXXX
~C~Pl XXXXXXXXXXXXXXXXXXXX
O
~NNNNNNNNNNNNNNNNN
0~~
. I ' o C) ~cnO~N~O~Cocno~ N
_ ~NNNNNNr~ N NN~
X
o o o up Al s N al f , , , , , , , I, N
. I
O N I I
.
.C r Z
E f o _~ l o us N O
h TV
Ul _ r-l O O r O f r O O O O
,1 u, al al us o us o o o o o o O
u ray U) f ,r rl E W H
. X X I H
X X X XX X X X
I: u f x x I: x x x x x o l N N N N N N N N
-I h r cn o N
2t7 Examples 8-13 illustrate the effect of the ratio of-elastomer core to rigid shell and the advantage of having sufficient hard shell around the soft core to protect the core and permit formation of a dispersion of the coagu-lated core//shell polymer with particles of size compar-able to the size of the original polybutadiene core.
Electron microscopy reveals that the polyblend of example 11 contains a uniform dispersion of particles of core shell polymer of a size (about 0.3 micron) similar to the size of the original agglomerated polybutadiene latex.
The polyblend has high impact strength When the amount of rigid shell protecting the polybutadiene is reduced in examples 9 and 10, electron microscopy shows that the dispersion in the polyamide is much less complete and mechanical tests show reduction in the impact strength with reduction in the amount of rigid shell. Even at a 1:1 core:shell ratio, multiphase core~/shell polymers prepared from polybutadiene latex of particle size 0.13 are not uniformly dispersed in polyamide, and the poly-blends have low impact strength. (examples 12, 13). In contrast although the elastomer content of example 8 is substantially lower than the elastomer content of ex-amples 12 and 13 the notched impact strength is substan-tially higher.
Example 14, 17 and 18 show that polyblends containing multiphase core//shell polymers in which acid monomers other than monoethyl maleate are incorporated into the rigid shell, also show improved toughness.
Examples 15~ 16 and 19 to 26 contain core//shell polymers with shells comprising various amounts of inter-polymerized acid monomer. The data suggest that an opti-mum acid concentration occurs in the range of about 5 to 15 weight percent corresponding to a concentration of carboxy groups in the range of about 1.6 to about 4.8 weight percent.
A further advantage of the core//shell modified poly-amide compositions resides in their high impact strengths at low temperaturesO Table 3 sets forth the data obtained at -4~C.
,2t7 Example Notched Impact IDI, J, -40C
, J/m notch at -40C
Polyamide 2 49 5 to 76 2~ 179 48 158 4~
2~ 2al 53 32 1~8 63 37 lay 19
4~ 146 73 43 1~4 57 2~7 -24- ~-08-12-1182 GLASS FIBER COMPOSITES
.... . .
Glass fiber composites are obtained by blending glass fiber with polyamide core//shell multiphase polymer blends at a concentration of 13 weight percent glass fiber based on the total weight of the composite. Data are presented in table 4 comparing polyamide 1 reinforced with glass fiber and a blend of polyamide 1 and core//
shell polymer II reinforced with glass fiber The compo-sites containing core//shell polymer show greatly im-proved Izod toughness and improved elongakion withoutsignificant sacrifice in tensile strength and resistance to heat distortion.
. Lo 2Z~7 H
O Us 4 l 111 . I
or N N N
ED
U~l O
_t D X co I_ , N
CO
f N t't N
r-i Eel ~0 C:
f En U
H Z; I` In Z; I; a- co o . . .
Us H S
Us ~~
O Pi En O o or I: U
o a.
Q O
N
m I;
o ox I
H I _ Ed E lo ED
Pi Us ) l I
US ~Z;. l 1 U: O O O l I l I.) C.) `-tn Pi H N r' I
En ,1 ,~ I
O O
U3 to m O~O
1-l H
H
do Ln O 1`
~0
.... . .
Glass fiber composites are obtained by blending glass fiber with polyamide core//shell multiphase polymer blends at a concentration of 13 weight percent glass fiber based on the total weight of the composite. Data are presented in table 4 comparing polyamide 1 reinforced with glass fiber and a blend of polyamide 1 and core//
shell polymer II reinforced with glass fiber The compo-sites containing core//shell polymer show greatly im-proved Izod toughness and improved elongakion withoutsignificant sacrifice in tensile strength and resistance to heat distortion.
. Lo 2Z~7 H
O Us 4 l 111 . I
or N N N
ED
U~l O
_t D X co I_ , N
CO
f N t't N
r-i Eel ~0 C:
f En U
H Z; I` In Z; I; a- co o . . .
Us H S
Us ~~
O Pi En O o or I: U
o a.
Q O
N
m I;
o ox I
H I _ Ed E lo ED
Pi Us ) l I
US ~Z;. l 1 U: O O O l I l I.) C.) `-tn Pi H N r' I
En ,1 ,~ I
O O
U3 to m O~O
1-l H
H
do Ln O 1`
~0
Claims (8)
1. A multiphase core//shell polymer comprising about 50 to about 90 parts by weight of a cross-linked elastomer core and about 10 to about 50 parts by weight of a rigid thermoplas-tic polymer shell of glass transition temperature at least about 35°C., comprising from about 1 to about 25 parts by weight of an interpolymerized C1 to C4 monoalkyl maleate or fumarate, from about 20 to about 80 parts by weight of inter-polymerized styrene, from about 0 to about 79 parts by weight of an interpolymerized C1 to C8 alkyl acrylate or methacry-late and from about 0 to about 45 parts by weight of interpoly-merized acrylonitrile or methacrylonitrile based on 100 parts by weight of shell interpolymer, wherein the multiphase core//shell polymer has a core of weight average particle diameter of at least about 0.3 micron and a rigid shell of average thickness of at least about 0.025 micron.
2. The multiphase core//shell polymer according to claim 1 comprising from about 60 to about 80 parts by weight of elas-tomer core and from about 20 to about 40 parts by weight of rigid shell.
3. The multiphase core//shell polymer according to claim 1 wherein the core of the multiphase polymer has a weight average particle diameter in the range of about 0.3 to about 0.8 micron.
4. The multiphase core//shell polymer according to claim 1 wherein the core of the multiphase polymer has a weight average particle diameter in the range of about 0.3 to about 0.7 micron.
5. The multiphase core//shell polymer according to claim 1, 2 or 3 wherein the elastomer core comprises interpolymerized butadiene.
6. A process of preparing a multiphase core//shell polymer which comprises:
preparing an aqueous emulsion of an elastomeric core polymer of weight average particle size in the range of at least about 0.3 micron;
graft polymerizing on the elastomeric core a rigid shell comprising from about 1 to about 25 parts by weight of an interpolymerized C1 to C4 monoalkyl maleate or fumarate, from about 20 to about 80 parts by weight of interpolymerized styrene, from about 0 to about 79 parts by weight of an inter-polymerized C1 to C8 alkyl acrylate or methacrylate and from about 0 to about 45 parts by weight of interpolymerized acrylonitrile or methacrylonitrile per 100 parts by weight of shell interpolymer, wherein the rigid shell has a glass transi-tion temperature of at least 35°C. and is of average thickness at least about 0.025 micron and wherein the weight ratio of core to shell is in the range of about 9:1 to about 1:1; and recovering the multiphase core//shell polymer from the aqueous emulsion.
preparing an aqueous emulsion of an elastomeric core polymer of weight average particle size in the range of at least about 0.3 micron;
graft polymerizing on the elastomeric core a rigid shell comprising from about 1 to about 25 parts by weight of an interpolymerized C1 to C4 monoalkyl maleate or fumarate, from about 20 to about 80 parts by weight of interpolymerized styrene, from about 0 to about 79 parts by weight of an inter-polymerized C1 to C8 alkyl acrylate or methacrylate and from about 0 to about 45 parts by weight of interpolymerized acrylonitrile or methacrylonitrile per 100 parts by weight of shell interpolymer, wherein the rigid shell has a glass transi-tion temperature of at least 35°C. and is of average thickness at least about 0.025 micron and wherein the weight ratio of core to shell is in the range of about 9:1 to about 1:1; and recovering the multiphase core//shell polymer from the aqueous emulsion.
7. The process of claim 6 wherein the core of the multi-phase polymer has a weight average particle diameter in the range of about 0.3 to about 0.8 micron.
8. The process of claim 6 wherein the core of the multi-phase polymer has a weight average particle diameter in the range of about 0.4 to about 0.7 micron.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/202,957 US4306040A (en) | 1980-11-03 | 1980-11-03 | Multiphase core//shell polymers |
| US202,957 | 1980-11-03 | ||
| US06/306,972 US4375532A (en) | 1980-11-03 | 1981-08-30 | Multiphase core/shell polymers |
| US306,972 | 1981-09-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1189227A true CA1189227A (en) | 1985-06-18 |
Family
ID=26898174
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000389209A Expired CA1189227A (en) | 1980-11-03 | 1981-11-02 | Multiphase core//shell polymers |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US4375532A (en) |
| EP (1) | EP0055890B1 (en) |
| CA (1) | CA1189227A (en) |
| DE (1) | DE3170639D1 (en) |
Families Citing this family (23)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5939347A (en) * | 1982-08-27 | 1984-03-03 | Mitsubishi Chem Ind Ltd | Surface functional type anion exchange resin and preparation thereof |
| US4495324A (en) * | 1983-10-24 | 1985-01-22 | Allied Corporation | Glass reinforced polyamide composition containing acrylic core/shell polymer |
| NL8304029A (en) * | 1983-11-23 | 1985-06-17 | Dow Chemical Nederland | RUBBER-REINFORCED POLYMERS OF MONOVINYLIDE AROMATIC COMPOUNDS HAVING A VERY GOOD RATIO BETWEEN GLOSS AND STRENGTH PROPERTIES AND A PROCESS FOR THEIR PREPARATION. |
| US4614767A (en) * | 1985-07-29 | 1986-09-30 | Atlantic Richfield Company | Moldable polyester-sulfone thermoplastic resin |
| GB8520842D0 (en) * | 1985-08-20 | 1985-09-25 | Bip Chemicals Ltd | Thermoplastic polyamide compositions |
| US4882382A (en) * | 1985-12-13 | 1989-11-21 | Monsanto Company | Rubber modified reaction molded nylon-6 block copolymers |
| US5051469A (en) * | 1985-12-13 | 1991-09-24 | Monsanto Company | Rubber modified reaction molded nylon-6 block copolymers |
| US4994524A (en) * | 1985-12-13 | 1991-02-19 | Monsanto Company | Rubber modified reaction moldable nylon-6 compositions |
| US5112908A (en) * | 1986-12-23 | 1992-05-12 | E. I. Du Pont De Nemours And Company | Tough polyamide compositions having high melt flow for complex moldings |
| DE3720475A1 (en) * | 1987-06-20 | 1988-12-29 | Bayer Ag | THERMOPLASTIC SILICONE RUBBER GRAFT POLYMERISATE (II) |
| US4888395A (en) * | 1987-07-02 | 1989-12-19 | Mobil Oil Corporation | Core/shell polymers and improved sealable articles treated with the same |
| TW241270B (en) * | 1991-08-13 | 1995-02-21 | Rohm & Haas | |
| US5380785A (en) * | 1993-04-05 | 1995-01-10 | The Goodyear Tire & Rubber Company | Rubbery polymer |
| DE69511615T2 (en) * | 1994-05-20 | 1999-12-09 | Ube Industries | Polyamide matrix with resin composite material containing dispersed polyolefin grains |
| JP3379559B2 (en) * | 1994-08-12 | 2003-02-24 | チッソ株式会社 | Hot press molding sheet |
| JP2766875B2 (en) * | 1995-04-10 | 1998-06-18 | 日本ピラー工業株式会社 | Shaft sealing system device |
| FR2735134B1 (en) * | 1995-06-09 | 1997-07-11 | Rhone Poulenc Chimie | WATER REDISPERSABLE POWDERS OF FILM-FORMING POLYMERS WITH CORE / BARK STRUCTURE |
| US7507471B1 (en) * | 1995-10-10 | 2009-03-24 | Isola Usa Corp | Reducing dusting of epoxy laminates |
| DE10260065A1 (en) * | 2002-12-19 | 2004-07-01 | Röhm GmbH & Co. KG | Core-shell particles for toughening of poly (meth) acrylate molding compounds |
| US7795343B2 (en) * | 2005-12-13 | 2010-09-14 | Rohm And Haas Company | Polymer composition |
| EP2336235B1 (en) * | 2009-12-18 | 2012-10-03 | Actega Artistica S.A. | Water-based dispersion of thermoplastic polymer and non-thermoplastic elastomer |
| US9115291B2 (en) | 2010-11-15 | 2015-08-25 | Sun Chemical Corporation | Compositions and methods to improve the setting properties and rub resistance of printing inks |
| WO2013086231A1 (en) | 2011-12-08 | 2013-06-13 | Sun Chemical Corporation | Overprint varnishes with non-aqueous dispersions |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3668274A (en) * | 1970-09-10 | 1972-06-06 | Rohm & Haas | Acrylic modifiers for polycarbonamides |
| US3984497A (en) * | 1971-12-13 | 1976-10-05 | Rohm And Haas Company | Acrylic modifiers for polycarbonamides |
| JPS5239636B2 (en) * | 1973-05-01 | 1977-10-06 | ||
| US4097551A (en) * | 1976-12-20 | 1978-06-27 | Arco Polymers, Inc. | Rubber modified dicarboxylic acid copolymer blends |
| EP0001245B1 (en) * | 1977-09-20 | 1982-01-27 | Bayer Ag | Impact-resistant polyamide masses and their use in mouldings |
| DE2906222A1 (en) | 1979-02-17 | 1980-08-28 | Bayer Ag | POLYMER BLENDS |
| US4306040A (en) * | 1980-11-03 | 1981-12-15 | Monsanto Company | Multiphase core//shell polymers |
-
1981
- 1981-08-30 US US06/306,972 patent/US4375532A/en not_active Expired - Fee Related
- 1981-10-30 EP EP81305171A patent/EP0055890B1/en not_active Expired
- 1981-10-30 DE DE8181305171T patent/DE3170639D1/en not_active Expired
- 1981-11-02 CA CA000389209A patent/CA1189227A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| EP0055890B1 (en) | 1985-05-22 |
| US4375532A (en) | 1983-03-01 |
| EP0055890A1 (en) | 1982-07-14 |
| DE3170639D1 (en) | 1985-06-27 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA1189227A (en) | Multiphase core//shell polymers | |
| US4306040A (en) | Multiphase core//shell polymers | |
| US4707513A (en) | Tough thermoplastic nylon compositions | |
| US4584344A (en) | Tough thermoplastic nylon compositions | |
| US4495324A (en) | Glass reinforced polyamide composition containing acrylic core/shell polymer | |
| EP1222218B1 (en) | Improved mass polymerized rubber-modified monovinylidene aromatic copolymer compositions | |
| CA1235834A (en) | Thermoplastic resin composition comprising a rubber modified copolymer | |
| CA1332992C (en) | Impact-strength modifiers for thermoplastic polymers | |
| CA1171996A (en) | Composition including a multiphase core/shell polymer and a polyamide matrix | |
| JPH0733473B2 (en) | Filled polymer blend | |
| JP2003534433A (en) | Weatherable polymer blends, their use and molded articles obtained therefrom | |
| CA1172789A (en) | POLYMERIC MATERIAL COMPRISING A POLYAMIDE BONDED TO A COPOLYMER CONTAINING AN IMIDE OF AN .alpha.,.beta. UNSATURATED CARBOXYLIC ACID | |
| US4423186A (en) | Impact resistant polyamide moulding compositions | |
| JP2733326B2 (en) | Reinforced / filled blends of thermoplastic interpolymers and polyamides and methods for their preparation | |
| CA2027381A1 (en) | Core-shell polymer, resin composition and molded article thereof | |
| US5010138A (en) | Thermoplastic interpolymers and their use in mixtures of polyamide and styrene copolymers and/or graft polymers | |
| US4755564A (en) | Graft polymers | |
| MX2011006484A (en) | Rubber-reinforced vinyl aromatic (co)polymer, having an optimum balance of physico-mechanical properties and a high gloss. | |
| JPH0145499B2 (en) | ||
| AU638459B2 (en) | Polyamide, polyglutarimide, and impact modifier blends | |
| JP2870540B2 (en) | Thermoplastic molding compound | |
| CA1237215A (en) | High-impact polyamide moulding compositions | |
| JPH11315184A (en) | Vinyl aromatic polymer/ketone polymer composition | |
| AU631977B2 (en) | Process to blend polyamides and functionalized elastomers and blends prepared by this method | |
| JP3978272B2 (en) | Damping thermoplastic resin composition |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry | ||
| MKEX | Expiry |
Effective date: 20020618 |