JPH0145499B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to thermoplastic polyamide compositions, and more particularly to multiphase thermoplastic polyamides containing elastic multiphase polymers with enhanced impact resistance and durability. Many prior art techniques exist regarding improving the impact strength of polyamides. Various additives have been added to polyamides to provide some improvement in toughness. Many of these additives are elastic in nature. For example, US Pat. No. 3,668,274 by Owens et al.
The specification describes (A) a first crosslinked elastomer phase of a copolymer or terpolymer and (B) a final rigid phase containing amine-reactive sites, preferably carboxylic acid groups, modified in a thermoplastic step. The authors teach that the impact strength of polyamides is moderately improved.
This soft modifier is coated with a rigid layer and apparently negates the significant improvement in toughness of the polyamide. U.S. Pat. No. 4,167,505 discloses that the polymeric modifiers of U.S. Pat. No. 3,668,274 provide improved impact strength of high molecular weight polyamides, but the resulting blends exhibit good flow properties necessary for injection molding operations. Owens et al.'s core shell polymers with high rubber core contents cannot be mixed with or dispersed in low molecular weight nylons due to the very low viscosity of nylons above their melting points. and the resulting insufficient shear makes it difficult to disperse viscous ingredients in a fluid medium. Another approach to the problem of improving the toughness of polyamides is provided by US Pat. No. 4,174,358. Toughened multiphasic polyamides are obtained by incorporating elastomers modified by copolymerization or reaction with monomers containing functional groups, such as carboxy groups, which can react or hydrogen bond with the polyamide. This approach has been used with acrylates, polyethylene, ethylene-propylene rubber, ethylene-propylene-diene rubber and ethylene-vinyl acetate copolymers. The resulting functionalized bulk rubber or elastomer requires very high shear in order to be finely dispersed in the polyamide matrix. Therefore, the rubber must be soluble (ie, free from cross-linking) to enable flow and dispersion upon heating. Since rubber particles are soluble and deformable, their final size is highly dependent on the intensity of shear during extrusion and molding. The desired fine rubber dispersion is difficult to obtain without strong shear, and control of rubber particle size in the final molding is not easily obtained. US Pat. No. 4,221,879 essentially consists of a polyamide and a graft product of polybutadiene as graft substrate and a mixture of acrylate or methacrylate and acrylonitrile and/or acrylamide monomers grafted thereon. A high impact polyamide is disclosed. The grafted shell is generally elastic in nature. Grafting products containing rigid shells, such as styrene copolymer shells, have been found to be unsatisfactory, apparently because of their poor compatibility with polyamides. According to the present invention, 55 to 99 parts by weight of a polyamide matrix resin with a number average molecular weight ranging from about 5,000 to about 30,000, and 50 to 90 parts by weight of a cross-linked elastomer core and 10 to 50 parts by weight of a rigid thermoplastic resin. A coalesced shell, which contains from about 1 to about 25 parts by weight copolymerized ethylenically unsaturated carboxylic acid monomer per 100 parts by weight of the shell, from about 20 to about 80 parts by weight copolymerized styrene,
about 0 to about 79 parts by weight of a copolymerized _C1 - _C8 alkyl acrylate or methacrylate and about 0
The present invention provides multiphase thermoplastic compositions consisting essentially of 1 to 45 parts by weight of a multiphase core shell containing up to about 45 parts by weight of copolymerized acrylonitrile or methacrylonitrile. The term "consisting essentially of" means that this tough material is in addition to the required polyamide matrix resin and multiphase core shell polymer unless the fundamental and essential properties of the composition are significantly adversely affected thereby. This means that other ingredients may be present in the composition. The polyamide matrix resins of the toughened compositions of the present invention are well known in the art and are commonly referred to as nylons.
These semicrystalline and amorphous resins have number average molecular weights in the range of . Preferably the molecular weight is in the range of about 8,000 to 20,000. Suitable polyamides include U.S. Pat. No. 2,071,250;
Examples include those described in the specifications of No. 2071251, No. 2130523, No. 2130948, No. 2241322, No. 2312966, No. 2513606, and No. 3393210. This polyamide resin can be produced by condensing equimolar amounts of a saturated dicarboxylic acid having 4 to 12 carbon atoms and a diamine having 4 to 14 carbon atoms. Excess diamine can be used to provide an excess of amine end groups over carboxyl end groups in the polyamide.
Examples of polyamides include polyhexamethylene adipamide (nylon 66), polyhexamethylene azeramide (nylon 69), polyhexamethylene sebacamide (nylon 610), polyhexamethylene dodecanoamide (nylon 612), and bis(nylon 612). (p-aminocyclohexyl)methandodecanamide. Polyamide resins can also be produced by ring opening of lactams (eg polycaprolactam and polylauryllactam) and condensation of ω-aminocarboxylic acids (eg poly-11 aminoundecanoic acid). Copolyamides made from copolymers of two or more of the aforementioned polymers or their components can also be used. Preferred polyamides are nylon 6, nylon 6,6, and nylon 6-nylon 6,6 copolymers. Preferably this polyamide is 200
It is a linear type with a melting point above ℃. A major proportion of the composition, up to 99% by weight, may be comprised of polyamide. However, preferred compositions contain 55-95% by weight, and more preferably 65-90%
% polyamide by weight. Selecting the number average molecular weight of the polyamide to be in the range of 5000 to 30000, preferably 8000 to 20000,
A polyamide composition is produced that is easily moldable by injection or extrusion techniques. Molecular weight is determined by end group analysis. The multiphase core-shell polymers of the present invention are elastomer-based composite copolymer materials having a cross-linked elastomer core and a rigid thermoplastic polymer shell. The elastomer core can be a diene elastomer, an ethylene-propylene-diene rubber, an acrylic elastomer or a polyurethane elastomer. Diene elastomers include polybutadiene, polyisoprene, polychloroprene and poly(cyanobutadiene). The diene can be copolymerized with up to about 50% by weight of other monomers such as alkyl acrylates and methacrylates, styrene, alpha-methylstyrene, acrylonitrile and substituted acrylonitriles, vinyl ethers, vinyl amides, vinyl esters, and the like. Acrylic elastic body is
50 to 99.9 parts by weight of alkyl acrylates having 1 to 10 carbon atoms, preferably 2 to 8 carbon atoms, 0 to 40
parts by weight of other ethylenically unsaturated monomers and
0.1 to 5 parts by weight of polyunsaturated cross-linking monomers such as polyacrylic and polymethacrylic esters of polyols such as butylene diacrylate and dimethacrylate, trimethylolpropane trimethacrylate, etc., vinyl acrylate and methacrylate, divinyl and trivinylbenzene, etc. includes. Grafting monomers having two or more additional polymerizable unsaturated groups optionally participating in the polymerization in different proportions can be included in amounts from about 0.1 to about 5 parts by weight. Preferably, the grafting monomer has at least one reactive group that polymerizes at about the same rate as the other monomers, or at a slightly slower rate. The remaining reactive groups, on the other hand, polymerize at a substantially slower rate. Differences in polymerization rates result in residual unsaturation levels in the elastomer core, particularly during later stages of polymerization, and thus at or near the surface of the elastomer particles. When the rigid thermoplastic shell is then polymerized on the surface of this elastomer, this residual unsaturated addition-polymerizable reactive group provided by the grafting monomer participates in the next reaction, resulting in less of the rigid shell being polymerized. Both parts are chemically bonded to the surface of the elastic body. The crosslinked elastomer core preferably has a glass transition temperature of about -25°C or less, and a solubility parameter close to that of a good "solvent" or polymer for the elastomer and in polarity and hydrogen bonding capacity. It has a swelling index ranging from about 2 to 20 as measured in similar solvents. That is, for polybutadiene, suitable solvents for swelling index measurement include benzene, toluene, and tetrahydrofuran, and for acrylic elastomers, suitable solvents include acetone, benzene, and toluene. Elastic cores are manufactured by bulk, emulsion and solution methods. Those manufactured in bulk or by solution method are
Prior to addition polymerization of the rigid polymer shell thereto, it is converted to the aqueous emulsion state by known techniques. The rigid thermoplastic polymer shell contains from about 1 to about 20 copolymerized ethylenically unsaturated monomers containing strong hydrogen bond-forming groups such as hydroxy, carboxy, or primary or secondary amine groups. It is contained in an amount of %. Typical monomers that may be used are carboxylic acid monomers such as acrylic acid, methacrylic acid, itaconic acid, mesaconic acid, citraconic acid, aconitic acid, fumaric acid and maleic acid, and ethylenically unsaturated dibasic acids and C Monoesters of ₁ - _C6 alcohols e.g. monomethyl maleate,
These include monohexyl maleate, monocyclohexyl maleate, monomethyl fumarate, monobutyl fumarate, and others. Preferred carboxylic acid monomers include ethylenically unsaturated dibasic acids and C ₁
Monoesters of ~ _C4 alcohols such as monomethyl, monoethyl and monobutyl maleate. Hydroxy monomers include C ₁ -C ₄ hydroxyalkyl esters of the above carboxylic acid monomers, such as 2-hydroxyethyl acrylate, 3
-Hydroxypropyl methacrylate, di-2-
(hydroxyethyl maleate), di-(2-hydroxypropyl) fumarate, and others. Amide monomers include acrylamide, methacrylamide and mono-N-alkylacrylamide and methacrylamide in which the alkyl group contains from 1 to 4 carbon atoms. As the amino group-containing rigid polymer shell, vinylamine and N-vinylimide (for example, N-vinylimide obtained by partial hydrolysis of poly(N-vinylimide) after graft polymerization onto an elastic core) are used.
- reacting a copolymer of vinyl succinimide and N-vinylphthalimide) and an amino monomer (e.g. ethyleneimine with a multiphase core-shell polymer containing the corresponding copolymerized carboxylic acid monomers in a rigid shell) Examples include copolymers of 2-aminoethyl acrylate, 2-aminoethyl methacrylate and methyl-2-aminoethyl maleate obtained by this method. The comonomer for the formation of the thermoplastic polymer shell has a rigid polymer glass transition temperature of at least about 35°C.
is selected so that They are advantageously selected to produce a solubility parameter of at least about 9.5 cal ^1.5 /cm ^0.5, ie, a moderately to highly polar, rigid thermoplastic polymer. The combination of polar and hydrogen bonding properties provided by relatively high solubility parameters and strongly hydrogen bonding comonomers provides a degree of compatibility of rigid thermoplastic polymers with polyamide matrices. Therefore, the dispersibility of the core-shell polymer in the polyamide matrix is enhanced so that a uniform dispersion of elastomer particles of approximately the same size as the initial elastomer latex is easily achieved, and the impact of the polyamide derived from the elastomer is enhanced. It is believed that strength improvement is optimized. Preferably the solubility parameter is at least about 10 cal ^1.5 /cm ^0.5 and about
16cal ^1.5 /cm ^0.5 or less. Solubility parameters are conveniently determined by the intrinsic viscosity method for the soluble fraction of rigid thermoplastic polymers or by the swelling method for crosslinked polymers. Comonomers are ethylenically monounsaturated monomers such as C ₁ -C ₈
Alkyl acrylates and methacrylates, styrene, vinyltoluene, α-methylstyrene,
It can be chosen from vinyl ester, acrylonitrile or vinylimide. Among the preferred comonomers are methyl methacrylate, styrene, α-
There are methylstyrene, acrylonitrile and methacrylonitrile. When the proportion of strongly hydrogen-bonded monomers is low, a high proportion of polar monomers such as methyl methacrylate, acrylonitrile or methacrylonitrile increases the solubility parameters and the compatibility of the shell polymer with the polyamide matrix polymer. . However, if the proportion of strongly hydrogen-bonding monomers is high, non-polar monomers such as styrene can be used as the only comonomer. Among the preferred rigid polymer compositions are about 1 to about 25 parts by weight of copolymerized ethylenically unsaturated carboxylic acid per 100 parts by weight of shell.
20 to about 80 parts by weight of copolymerized styrene, about 0 to about 80 parts by weight
about 79 parts by weight of an ethylenically unsaturated _C1 - _C8 alkyl acrylate or methacrylate and about 0 to
an ethylenically unsaturated carboxylic acid monomer comprising about 45 parts by weight of acrylonitrile or methacrylonitrile, styrene, a _C1 - _C8 alkyl acrylate or methacrylate, and a glass at least about 35°C comprising acrylonitrile or methacrylonitrile. There are transition temperature compositions. Preferably, the ethylenically unsaturated carboxylic acid is selected from the group consisting of monomaleates and monofumarates of _C1 - _C4 alcohols, and acrylic and methacrylic acids. Multiphasic core-shell polymers are made of elastomer by known techniques convenient for forming a shell of rigid thermoplastic polymer around an elastomer core rather than discrete particles of rigid polymer separated from the core. It is produced by emulsion polymerization of shell comonomers in the presence of a core emulsion. Emulsion polymerization of this shell comonomer on an elastomer core is preferably carried out at a temperature of 10° C. above the melting point of the polyamide and at a shear rate of 1000 s ⁻¹ for the polymer coagulated from the emulsion and dried. The apparent melt viscosity of the core shell polymer, when measured, is controlled so that it does not exceed about 10 times the apparent melt viscosity of the polyamide, and is preferably in the range of 1 to 8 times the apparent melt viscosity of the polyamide. be done. For nylon 6,6 compositions, the temperature for this apparent melt viscosity measurement is 260°C.
The degree of polymerization can be conveniently controlled by adding appropriate amounts of chain transfer agents such as mercaptans, polyhalogen compounds or allyl compounds. The elastomer core emulsion is preferably of a weight average particle diameter of 0.3μ or greater, and the thickness of the rigid polymer shell, calculated from the weight added to the core elastomer, is approximately equal to the thickness of the core shell particles upon coagulation and drying. More preferably, the particle diameter is at least about 0.025μ to prevent sintering and facilitate the formation of a uniform dispersion of the core-shell polymer in the polyamide. 0.8μ, and even more preferably it is in the range of about 0.4 to about 0.7μ so that the stiffness weight necessary to prevent agglomeration and sintering of the emulsion particles during the solidification and drying steps is The percentage of combined shells is minimized. When the elastomer core includes a butadiene or acrylic polymer prepared by emulsion polymerization, the particle size is generally within the range of about 0.1 to about 0.2 microns. Seeding techniques can provide emulsions with larger particle sizes. However, the emulsion polymerization conditions that favor the formation of large particle sizes result in significant elastomer core coagulation that causes vessel fouling and reduces the formation of fine, uniform dispersions of multiphase core-shell polymers in polyamides. Generally, a butadiene and acrylic elastomer core emulsion with a large particle size in the range of about 0.3 to about 0.8μ is produced by controlled agglomeration of an emulsion with a particle size of 0.1 to 0.2μ. is preferred. Agglomeration can be accomplished by any conventional means, such as by adding a suitable amount of a water-soluble carboxylic acid or anhydride of such acid. The agglomerated emulsion is then stabilized by the addition of a suitable emulsifier. The amount of elastomer core in the multiphase core shell polymer can range from about 50 to about 90 parts by weight, with the amount of rigid polymer shell applied thereto from about 10 to about 50 parts by weight. More preferably, the amount of elastomeric core ranges from about 60 to about 80 parts by weight and the amount of rigid polymeric shell ranges from about 20 to about 40 parts by weight. The polymerization of the rigid polymer shell is carried out under conditions that favor polymerization at or on the surface of the elastomeric core emulsion, such that no substantial number of new "seeds" or particles are formed in the emulsion. Implemented. This is generally achieved by controlling the amount of emulsifier or initiator and controlling the rate of addition of monomer, emulsifier and initiator. Preferably no further emulsifier is added after forming the core elastomer emulsion. Once the polymerization is substantially complete, the multiphase core-shell polymer can be prepared by any convenient method such as freezing, addition of a coagulating solvent such as methanol optionally containing a small amount of a strong acid such as hydrochloric acid, or a polyvalent metal salt such as magnesium sulfate or aluminum sulfate. It is solidified by the addition of an aqueous solution of . The coagulated emulsion is washed thoroughly with water to remove emulsifiers and salts and dried, preferably at a temperature of at least about 10°C below the glass transition temperature of the rigid polymer shell. Blends of polyamide and multiphasic core-shell polymers have a melting point of about 5 to about 100 degrees below the melting point of the polyamide.
They are manufactured by melt blending them in a closed system at temperatures in the high range of °C. Single or twin screw extrusions can be advantageously used for this blending process. An advantage of the compositions of the present invention is their ease of blending in a single screw extruder and the ease with which uniform submicron dispersions of multiphase core shell polymers in polyamides are formed. It is in. Such an effect is only possible if the latex particles obtained after graft polymerization of the rigid shell onto the elastic core are able to retain their shape and size when dispersed in the polyamide by melt blending. believe that it can be achieved. To accomplish this, the polymer crumb obtained by coagulation of the latex should be able to break down into particles of grafted latex. In other words, the crumb after drying must have sufficiently loose clusters to allow its redispersion. This looseness is facilitated by a rigid polymer shell that prevents the elastomeric particles from sintering into a solid mass. The improved toughness of the multiphase thermoplastic compositions of the present invention when compared to unblended polyamides is demonstrated by higher notch Izod values and reduced % brittle failure in multi-axis driven dart tests. The Izod value increases steadily with increasing amount of elastomer core material in the thermoplastic composition, and this ranges from 300 to 1000 J/m notch when the elastomer content ranges from 12 to 18% by weight of the composition. in range. In other words, a value of 500 J/m notch can be easily obtained. Negligible elastomer concentration reduces the % brittle failure in multi-axis driven gate tests, and elastomer content
If it is 10% by weight or more, the percentage is reduced to zero. Significant improvements in notch impact strength at low temperatures, for example -40° C. and below, are also observed. The compositions of the invention contain one or more conventional additives such as stabilizers and inhibitors against oxidative, thermal and UV degradation, lubricants and mold release agents, colorants, nucleating agents and plasticizers. It can be denatured by twisting. Up to 50% by weight of glass fibers or fibrous and particulate inorganic fillers can increase the modulus and heat distortion resistance of the polyamide composition by a substantial degree. Stabilizers can be included in the thermoplastic composition at any stage in its manufacture.
Preferably, the stabilizer is included initially to preclude degradation from starting before the composition can be protected. Such stabilizers must be compatible with the powder composition. Oxidative and thermal stabilizers useful in the materials of this invention include those commonly used in polyamides, elastomers and addition polymers. These include, for example, group metals such as sodium in combination with cuprous halides (such as chlorides, bromides and iodides) and also sterically hindered phenols, hydroquinones, phosphites and various substituents of these groups and combinations thereof. , potassium and lithium halides. UV stabilizers include various substituted resorcinols, salicylates, benzotriazoles, benzophenones, and others. Suitable lubricants and mold release agents include stearic acid, stearic alcohol, stearamide, and organic dyes include nitrosine and others. Suitable pigments include titanium dioxide,
Examples include cadmium sulfide, cadmium selenide sulfide, phthalocyanine, ultramarine blue, carbon black, and others. Suitable fibrous and particulate fillers and reinforcing agents include carbon fibers, glass fibers, amorphous silica, asbestos, calcium silicates, aluminum silicates, magnesium carbonate,
Examples include kaolin, thioyoke, powdered quartz, mica, feldspar, and others. Nucleating agents include talc, calcium fluoride, sodium phenylphosphinate, alumina and finely divided polytetrafluoroethylene, among others. Plasticizers up to about 20% by weight, based on the weight of the composition, include dioctyl phthalate, dibenzyl phthalate, butylbenzyl phthalate, hydrocarbon oils, N-normal butylbenzenesulfonamide, N-ethyl o- and p-toluenesulfonamide. Others can be mentioned. The toughened thermoplastic compositions can be processed into a wide range of useful articles, including molded parts and extrudates, such as tubes, films, sheets, fibers and oriented fibers, laminates, etc., by conventional molding techniques used to mold thermoplastic articles. Can be processed into body and wire coatings. The following examples illustrate the invention, in which parts and percentages are by weight unless otherwise indicated. Preparation of Elastic Core Polymer Polybutadiene latex is prepared by polymerizing butadiene at 70°C using a redox initiator to 98% conversion. This latex has a solids content of 42% and a weight average particle size of 0.13μ. 200 parts by weight of this latex was mixed with 60 parts by weight of crushed ice.
1.1 parts by weight of acetic anhydride are quickly added and the latex is stirred vigorously for about 15 seconds and left undisturbed for 30 minutes. Next, this agglomerated latex is processed into "Gafac" 610 (GAF company product).
Approximately 9 per glycol molecule sold under the name
Stabilization is achieved by slowly and carefully adding 2 parts by weight of a mixture of mono- and diphosphate esters of alkyl phenoxypolyethylene glycols having 5 ethylene oxide units. The emulsifier is reduced to PH12 by the addition of sodium hydroxide solution.
It is added as a 10% aqueous solution adjusted to The agglomerated latex is gently stirred to evenly distribute the surfactant thereon. This agglomerated latex contains 29% rubber solids. The weight average particle size of the agglomerated latex is 0.5μ. Similarly, agglomerated polybutadiene latexes having weight average particle sizes of 0.29μ, 0.4μ and 0.64μ were prepared by adding 0.6 parts, 0.8 parts and 1.2 parts of acetic anhydride to 200 parts by weight of polybutadiene latex. Ru. Production of multiphase core shell polymers Polybutadiene 100 with 0.5μ weight average particle size
part by weight of the agglomerated latex was charged to a reaction vessel equipped with a temperature control device, two graduated holding tanks (for monomer and persulfate solution addition), a buffer, a Teflon blade stirrer, and a condenser; Dilute to approximately 20% solids with water. Displace the batch by bubbling nitrogen through it through a sparger for about 15-20 minutes. During this time, the batch was stirred gently and heated to 80°C.
shall be. 39 parts by weight of styrene, 18 parts by weight of acrylonitrile, 3 parts by weight of monoethyl maleate, and
A monomer mixture containing 0.75 parts by weight of terpinolene and an aqueous solution of potassium persulfate containing 0.90 parts of persulfate in 36 parts by weight of water are prepared. The monomer mixture and persulfate solution are charged to a holding tank, which also has a
Displace by bubbling nitrogen through for 10 minutes. A nitrogen atmosphere is maintained in the vessel and tank throughout the polymerization process. Approximately 10-15% monomer/initiator charge is added to the batch when the vessel contents reach 80°C. Stir this batch for about 15 minutes. At the end of this time, continuous addition of monomer and catalyst streams is started. 2
Adjust the addition rate for each stream to complete the addition in about 4 hours. Polymerization is then continued for an additional hour at 80°C. Monomer conversion is 95%. At the end of polymerization,
Pass this batch through cheesecloth. Despite the fact that generally no additional emulsifier is added during the polymerization process, little coagulum is obtained. This latex was made of 25% by weight of mixed alkylated aryl phosphite under the trade name "Polygard" sold by Uniroyal.
and an aqueous emulsion containing 12.5% by weight of 2,6-ditert-butyl-4-methylphenol sold by Shell Chemical Corporation under the trade name "Ionol". The amounts added are such as to provide 2 parts of polyguard and 1 part of ionol per 100 parts of polybutadiene charged. The resulting stabilized latex was treated with magnesium sulfate at 95-98°C.
Coagulate by adding it to a 3% aqueous solution of the hydrate. 2 to 3 parts by volume of magnesium sulfate solution are used per part by volume of latex. The solidified material is washed several times with cold filtered water on the filter.
Most water is removed by vacuum filtration or centrifugation. The remaining water is removed in a vacuum oven at 60-70 °C. Continue drying until no trace of moisture can be detected in the dry ice/acetone trap. The ratio of elastic core to rigid shell is 1:
It is 0.6. Grafting efficiency is 28%. The intrinsic viscosity of the soluble fraction of the rigid shell is 0.32. The apparent melt viscosity of the multiphase polymer is 260°C and 10 ³ seconds
5.8 kilopoise (K-) at a shear rate of ^-1
poise). This example is listed as Example 1 in Table 1. The apparent melt viscosity of Polyamide 1 in Table 2 under the same conditions is 1.5 kilopoise. Similarly, by selecting polybutadiene latexes of appropriate particle size by the same method, multiphase core-shell polymers of different core-shell ratios and different rigid polymer shell compositions are prepared.

【table】

Table: Grafting Efficiency of Multilayer Core Shell Polymers Grafting efficiency is measured by extracting from the polybutadiene graft the shell polymer that is not chemically bonded or grafted to it. The latex portion obtained at the end of the grafting (prior to the addition of stabilizers) is coagulated in a large excess of acidified methanol. The coagulum is washed several times on the filter with methanol and then dried at 60°C. The dried material is then compression molded into a solid sheet in a mold heated to about 150°C.
Note that compression molding of the crumb into a sheet is necessary to avoid colloidal dispersion of the rubber during extraction with acetone. This compression molded sheet is cut into strips. A carefully measured weight of material (about 2 g) is then placed in about 50 ml of acetone for about 18-20 hours. Remove the clear acetone solution with a syringe and collect. This extraction operation is repeated once more and all the collected acetone solution is dried by solvent evaporation. The dry weight of acetone soluble material (ie, the portion of the shell polymer 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 preweighed molded strip is calculated. Grafting efficiency is the weight ratio of shell polymer that is not extracted with acetone to the total weight of shell polymer present in the sample. Grafting Efficiency=W-We/W where W is the total weight of shell in the sample and We is the weight of extracted shell polymer. Grafting efficiency is generally in the range of about 20-40% and is increased by decreasing the particle size of the polybutadiene core, decreasing the shell to core ratio, and decreasing the amount of chain transfer agent in the shell polymerization. Intrinsic viscosity and glass transition temperature of the non-grafted portion of the multiphasic core-shell polymer Extraction of the shell polymer is carried out with DMF (dimethylformamide). The crumb obtained by coagulation with MgSO ₄ is dried and formed into sheets as described above. Then the strip
Leaching in DMF. The solution passed through a glass filter is precipitated in acidified methanol/water (80:20). Filter the precipitate, wash with methanol/water and dry. Intrinsic viscosity of non-grafted shell polymer at 25℃
Measure in DMF. The glass transition temperature is measured on a DuPont Differential Scanning Calorimeter Model No. 900 using a sample size of about 0.1 to about 0.2 g. The heating rate is 20°C/min. Tg is the midpoint of the glass transition deflection. Preparation of Polyamide Blends The blend components are carefully dried before extrusion. 1 torr of polyamide in pellet form
Dry overnight at about 80° C. with pressure below. by inverting the separately dried multiphase core shell polymer in a drying vessel at a temperature about 10° C. below the glass transition temperature of the rigid polymer shell;
Mix with polyamide pellets and store in a sealed container ready for use. For melt blending, a single stage 2.54 cm Killion extruder with a two stage (vent plugging) 24:1 screw with a screw speed of 100 rpm is used. Has a breaker plate
Use a 40 mesh screen in the extruder nozzle. For nylon 6,6, the set temperature profiles for the various stages from the hopper to the nozzle are generally 285°C, 282°C, 277°C, 266°C and 266°C. The dried blend is charged to a nitrogen purged hopper and kept under nitrogen during the salt extraction process.
The extrudate is passed through a short section of water, a stream of air, and hot milled in a nitrogen purged jar. The extrudates are dried in vacuo at about 70° C. overnight. A second extrusion is then carried out. This second
The extrudates are again dried overnight at 70° C. before molding. Often, a slightly rough extrudate is produced at first, perhaps due to uneven distribution of the bulky rubber in the hopper and/or due to incompletely dispersed rubber.
obtained by extrusion. In the case of the second extrusion, generally smooth extrudates are obtained. Molding the Blend Injection molding is performed in a 1/2 oz. Arburg equipment. Typical molding conditions used for nylon 6,6 blends are as follows.

[Table] Apparent melt viscosity of polyamide and core shell polymer The apparent melt viscosity of the polyamide and multiphase core shell polymer components of the polyblend composition is 10:
Measurements are made in a Sieglaff-Mckelvey rheometer at a temperature of 10° C. above the polyamide melting point using a capillary length/diameter ratio of 1. Mechanical Properties in Polyblends Molded samples of polyamide and polyblends of multiphase core-shell polymers are subjected to mechanical testing in the "dry-as-molded" condition. The following tests are used: Notched Izot toughness ASTM D-256-56 Tensile strength ASTM D-638-58T Elongation ASTM D-638-58T Polymer tensile modulus ASTM D-882 Particle size Electron micrograph of microtome section of molded sample Multi-axis drive Gate tests are conducted using a 6.35 mm diameter and hemispherical head dart fired at a speed of 112 m/min. Data for Polyblend is given in Table 2. The matrix polyamide is nylon 6,6 and an 85:15 ratio nylon 6,6/nylon 6 copolymer with a number average molecular weight of 18,000. These matrix polymers are designated in Table 2 as Polyamide 1 and Polyamide 2, respectively. Examples 1-43 are within the scope of this invention. Examples A-F are included for comparative purposes.
Data for polyamides show that the notch impact strength is very low, and the impact resistance in the driven dart test is very high, with a significant frequency of brittle failure, ie 10%. At best, only moderate notch impact strength improvements are obtained when polyamides are blended with butadiene styrene core shell polymers (Example A) and butadiene styrene acrylonitrile core shell polymers (Examples B, C, and D). do not have. However, the frequency of brittle failure in the driven dart test increases. A slight improvement in impact strength and reduction in brittle failure is observed when carboxy monomers are introduced into the butadiene styrene coaciel polymer (Example E vs. Example A). Similarly, a small improvement in impact strength is observed for the core shell polymer containing acid-modified polymethyl methacrylate as the shell polymer (Example F). In contrast, if the shell includes carboxy monomers and styrene and acrylonitrile or acrylate or methacrylate monomers or acrylonitrile and acrylate or methacrylate monomers, the notch impact strength and brittle failure in the driven dart test Significant improvements in removal are obtained (Examples 1-43). Examples 4-7 provide a series of blends containing core shell polymers with reduced polybutadiene content. The notch impact strength decreases with decreasing butadiene content, but in all cases only malleable failure is observed in the driven dart test.
The improvement in notch impact strength over unblended polyamides is very significant when the butadiene content is about 12% or higher.

【table】

Table: Examples 8-13 demonstrate the effect of the elastomeric core/rigid shell ratio and the effect of solidified core shell polymers around the soft core that protect the core and have particles of a size comparable to the size of the initial polybutadiene core. It shows the advantage of having a sufficiently hard shell to allow dispersion formation. Electron micrographs show that the polyblend of Example 11 has a size similar to that of the initial agglomerated polybutadiene latex (approximately
Contains a homogeneous dispersion of core-shell polymer particles of 0.3μ). This polyblend has high impact strength. When the amount of rigid shell protecting the polybutadiene was reduced in Examples 9 and 10, electron micrographs showed that the dispersion in the polyamide was much more incomplete, and mechanical tests showed that the impact strength decreased with a decrease in the amount of rigid shell. It shows that the amount decreases. Even at a 1:1 core/shell ratio, multiphase core-shell polymers made from 0.13 particle size polybutadiene latex do not disperse uniformly in the polyamide, and this polyblend has low impact strength. (Example 12)
and 13). In contrast, although the elastomer content of Example 8 is substantially lower than that of Examples 12 and 13, its notch impact strength is substantially higher. Examples 14, 17 and 18 demonstrate that polyblends containing multiphase core shell polymers incorporated into rigid shells of acid monomers other than monoethyl maleate also have improved toughness. ing. Examples 15, 16, and 19-26 contain core-shell polymers with shells containing varying amounts of copolymerized acid monomers. The data shows that the optimal acid concentration is in the range of about 5-15% by weight, and this is about
It is suggested that this corresponds to a carboxy group concentration ranging from 1.6 to about 4.8% by weight. Another advantage of core-shell modified polyamide compositions is their high impact strength at low temperatures. Table 3 lists the data obtained at -40°C.

【table】

Table: Glass fiber composite A glass fiber composite is obtained by blending glass fibers with a polyamide core shell multiphase polymer blend at a concentration of glass fibers of 13% by weight based on the total weight of the composite. Data comparing glass fiber reinforced Polyamide 1 and a blend of Polyamide 1 and glass fiber reinforced core shell polymer is provided in Table 4. Composites containing core-shell polymers exhibit greatly improved isotonic toughness and improved elongation without significantly sacrificing tensile strength and thermal deformation resistance.

【table】

Claims (1)

Claims: 1. Essentially 55 to 99 parts by weight of a polyamide matrix resin with a number average molecular weight in the range of about 5,000 to 30,000, and about 50 to about 90% by weight of a crosslinked elastomer core and about 10 to 30,000 parts by weight of a cross-linked elastomer core. About 50% by weight of a rigid thermoplastic polymer shell having a glass transition temperature of at least about 35°C, which is about 1 to about 25 parts by weight copolymerized ethylenically unsaturated carboxylic acid per 100 parts by weight of the shell polymer. monomers, about 20 to about 80 parts by weight copolymerized styrene, about 0 to about 79 parts by weight copolymerized _C1 - _C8 alkyl acrylate or methacrylate, and about 0 to about 45 parts by weight copolymerized acrylonitrile or methacrylonitrile) comprising 1 to 45 parts by weight of a multiphasic core-shell polymer. 2 10℃ above the melting point of polyamide and 1000 seconds
The composition of claim ¹ , wherein the ratio of the apparent melt viscosity of the polyamide to the apparent melt viscosity of the multiphase core shell polymer at a shear rate of -1 is in the range of about 0.1 to about 1. 3. The multiphasic core-shell polymer has a core with a weight average particle diameter of at least about 0.3μ and a weight average particle diameter of at least about 0.025μ.
3. A composition according to claim 1 or claim 2, having a rigid shell having an average thickness of . 4. The composition of claim 3, wherein the multiphasic core-shell polymer has a core with a weight average particle diameter in the range of about 0.3 to about 0.8 microns. 5. The composition of claim 3, wherein the cross-linked elastomer core includes copolymerized butadiene. 6 Carboxylic acid monomers include acrylic acid, methacrylic acid, itaconic acid, mesaconic acid, citraconic acid, aconitic acid, fumaric acid and maleic acid, and those of itaconic acid, mesaconic acid, citraconic acid, aconitic acid, maleic acid and fumaric acid. _C1 ～ _C6
The composition according to claim 5, which is selected from the group consisting of alcohol monoesters. 7. The composition of claim 5, wherein the carboxylic acid monomer is selected from the group consisting of _C1 - _C4 monoalkyl maleate and fumarate. 8. The composition of claim 7, having a notch impact strength of at least about 300 J/m. 9. The composition of claim 3, wherein the polyamide is nylon 6, nylon 6,6 or nylon 6-nylon 6,6 copolymer. 10 Polyamide is nylon 6, nylon 6, 6
The composition according to claim 7, which is a nylon 6-nylon 6,6 copolymer. 11. The composition of claim 9, wherein the cross-linked elastomer core includes copolymerized butadiene. 12. A composition according to claim 3 containing up to 50% by weight of fibrous or particulate mineral filler. 13. A composition according to claim 3 containing up to 50% by weight of glass fibers. 14 Polyamide matrix resin is about 8,000 to about
A composition according to claim 1, having a number average molecular weight in the range of 20,000. 15 The weight average particle diameter of the core is about 0.4 to about 0.7μ
A composition according to claim 3, which is within the range of . 16. The composition of claim 1, consisting essentially of 65 to 90 parts by weight polyamide matrix resin and 10 to 35 parts by weight multiphasic core shell polymer. 17. The composition of claim 3, consisting essentially of 65 to 90 parts by weight polyamide matrix resin and 10 to 35 parts by weight multiphasic core shell polymer. 18. The composition of claim 7, consisting essentially of 65 to 90 parts by weight polyamide matrix resin and 10 to 35 parts by weight multiphasic core shell polymer. 19 (1) preparing an aqueous emulsion of an elastomeric core polymer with a weight average particle size ranging from about 0.3 to about 0.8 microns; and (2) copolymerizing from about 1 to about 25 parts by weight per 100 parts by weight of the rigid shell. from about 20 to about 80 parts by weight of copolymerized styrene, from about 0 to about 79 parts by weight of _C1 - _C8 alkyl acrylate or methacrylate, and from about 0 to about 45 parts by weight. about 9:1 of a rigid shell containing copolymerized acrylonitrile or methacrylonitrile in a ratio of about 9:1 and having a glass transition temperature of at least about 35°C and an average thickness of at least about 0.025μ.
A method of making a toughened multiphase thermoplastic composition comprising graft polymerizing onto an elastomer core at a core/shell weight ratio in the range of from to about 1:1. 20. The method of claim 19, wherein the polyamide has a number average molecular weight in the range of about 8,000 to about 20,000. 21 10°C above the melting point of polyamide and 1000
selecting the polyamide and the multiphasic core-shell polymer to provide an apparent melt viscosity ratio in the range of about 0.1 to about 1 when measured at a shear rate of sec ^-1 ;
A method according to claim 19. 22 The weight average particle size of the core is about 0.4 to about
22. A method as claimed in claim 21, in the range of 0.7μ. 23. The method of any of the preceding claims ₁₉ , 20, 21 or 22, wherein the carboxylic acid monomer is selected from the group consisting of C1- _C4 monoalkyl maleate and fumarate.