Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L35/00—Compositions 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 a carboxyl radical, and containing at least one other carboxyl radical in the molecule, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
  • C08L35/06—Copolymers with vinyl aromatic monomers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L51/00—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
  • C08L51/04—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers grafted on to rubbers

Definitions

• the present invention pertains to certainrubber-modified monovinylidene aromatic polymer compositions which exhibit a beneficial combination of physicl characteristics.
• ABS or ABS-type compositions generally comprise a combination of an elastomer, usually containing polymerized butadiene, with a rigid interpolymer of a monovinylidene aromatic monomer and an ethylenically unsaturated nitrile monomer.
• elastomer usually containing polymerized butadiene
• rigid interpolymer usually containing polymerized butadiene
• elastomer usually containing polymerized butadiene
• a rigid interpolymer of a monovinylidene aromatic monomer and an ethylenically unsaturated nitrile monomer ethylenically unsaturated nitrile monomer.
• ABS or ABS-type compositions usually consist of the rigid, matrix or continuous phase having dispersed therein particles of the elastomer, such particles usually having grafted thereto amounts of the rigid interpolymer or a similar inter- or homopolymer.
• 25 particles are usually formed and grafted in a mass-type or mass-suspension-type polymerization process where a previously-produced rubber is dissolved in one or more polymerizable monomers with optional diluents, which
• mass particles Occlusion- -containing particles, produced in such mass, mass-solution or mass-suspension processes or variations of these processes are hereafter referred to as "mass particles.” It is difficult, however, using available types of rubber and mass process equipment to produce groups of mass particles having volume average diameters less than 0.5 ⁇ .
• the other main type of rubber particle morphology i.e., the above-mentioned "solid” or non-occluded grafted rubber particle
• the other main type of rubber particle morphology is usually 5 achieved via emulsion polymerization of the rubber in the form of an aqueous latex.
• monomers which are polymerizable and graftable e.g., styrene and acrylonitrile
• emulsion particles The non-occluded type of rubber particles, produced via an emulsion polymerization process, are hereinafter referred to as "emulsion particles.”
• emulsion particles When these 5 emulsion particles have been grafted with a different, relatively rigid polymer, but still have a high rubber concentration, at least about 30 weight percent or so, these compositions are very suitable for blending with additional amounts of the same or different rigid 0 polymer, optionally containing additional amounts of rubber, to achieve desired rubber contents in the resultant compositions.
• Such blendable intermediates are often referred to as "grafted rubber concentrates" - and can be used to produce a wide variety of rubber- -modified polymer compositions.
• the heat distortion temperature or softening point of ABS or ABS-type 0 composition can be raised by incorporating into the compositions materials such as N-phenylmaleimide, ⁇ -methyl styrene, and copolymers of styrene with maleic anhydride.
• materials such as N-phenylmaleimide, ⁇ -methyl styrene, and copolymers of styrene with maleic anhydride.
• the incorporation of these materials into ABS or ABS-type compositions usually is accompanied by some decrease in other physical properties.
• the use of styrene-maleic anhydride can result in uncontrolled cross-linking at temperatures greater than 230°C, resulting in unpredictable decreases in impact and melt flow rate properties.
• ⁇ -methyl styrene as a comonomer can result in a composition which is difficult to process.
• the use of ⁇ -methyl styrene can lower the ceiling temperature of the resulting composition, the result being depolymerization and reduced physical properties. Accordingly, the use of certain materials may improve the heat distortion temperature of an ABS or ABS-type composition, but generally at the expense of other physical properties. Thus, a long-standing problem is the production of an ABS or ABS-type composition having a high heat distortion temperature while also exhibiting impact and tensile strength properties.
• U.S. Patent 4,567,233 discloses a rubber- -modified styrenic resin composition comprising up to four components.
• One component is a graft copolymer comprising a specific matrix resin and emulsion rubber particle having an average particle size of from 0.1 to 0.5 ⁇ .
• Another component is a graft copolymer comprising a specific matrix resin and a mass or mass-suspension rubber particle having an average particle size of from 0.7 to 4 ⁇ .
• the amount of the small particle component must be from 50 to 97 percent of the total weight of the two rubber-containing components.
• a third component includes a copolymer of a vinyl aromatic compound, a maleimide compound, and optionally a copolymerizable vinyl compound.
• An optional fourth component is a polymer of a vinyl aromatic compound and an unsaturated nitrile compound. Said patent discloses that such compositions have good heat stability and falling dart impact properties. However, the problem of tensile strength is not discussed
• the present invention is an improved rubber-modified, rigid, heat-and impact-resistant polymeric blend composition comprising:
• the weight average molecular weight of the interpolymer is at least 120,000
• the first graft copolymer composition comprises from 30 to 70 weight percent of a copolymer (A) grafted at least in part to from 30 to 70 weight percent of an emulsion rubbery substrate polymer, the substrate polymer having an average particle size of from 0.05 to 0.65 micron
• the said copolymer (A) comprises in polymerized form from 10 to 60 weight percent of an ethylenically unsaturated nitrile monomer and from 40 to 90 weight percent of a copolymerizable monovinylidene aromatic monomer,
• the second graft copolymer composition comprises a copolymer (B) grafted at least in part to a mass rubbery substrate polymer, the substrate polymer having an average particle size of less than one micron,
• copolymer (B) comprises in polymerized form from 15 to 36 weight percent of an ethylenically unsatuated nitrile monomer and from 64 to 85 weight percent of a copolymerizable monovinylidene aromatic monomer,
• the total rubber content of the said rubber-modified composition comprises from 8.5 to 13.5 weight percent
• the weight ratio of rubber particles prepared by mass polymerization to the total rubber content of the rubber-modified composition is from 0.09 to 0.4.
• Tensile strength is an important physical property for end uses such as automotive interior trim, lighting, cowl vents, air-directing grills, and other applications which require molded parts with the ability to bear loads and to withstand the forces associated with mechanical fastening.
• the compositions of the present invention are well-suited for such applications in view of the combination of tensile strength, heat resistance, and impact strength exhibited by these compositions.
• the present invention comprises three essential elements: (a) a monovinylidene aromatic / maleimide / ethylenically unsaturated nitrile interpolymer; (b) a first graft copolymer containing emulsion particles (rubber) dispersed therein; and (c) a second graft copolymer containing mass particles (rubber) dispersed therein.
• a monovinylidene aromatic / maleimide / ethylenically unsaturated nitrile interpolymer a first graft copolymer containing emulsion particles (rubber) dispersed therein
• a second graft copolymer containing mass particles (rubber) dispersed therein emulsion particles
• the first of the three above-mentioned essential elements of the present invention comprises an interpolymer having polymerized therein maleimide monomer, monovinylidene aromatic monomer and ethylenically unsaturated nitrile monomer.
• these interpolymers are hereinafter referred to as "MSAN-type" since the most common example of these polymers is prepared from a maleimide monomer, styrene, and acrylonitrile.
• the MSAN-type interpolymer preferably is formed from 15 to 43 weight percent of ethylenically unsaturated nitrile monomer, 14 to 75 weight percent of monovinylidene aromatic monomer, and 8 to 50 weight percent of maleimide monomer.
• the weight average molecular weight of the MSAN-type polymer advantageously is at least 120,000 and preferably is at least 150,000.
• the composition of the present invention comprises from 7 to 76 weight percent of the MSAN-type polymer.
• Examples of the monovinylidene aromatic 5 monomers which, in polymerized form, may be included in compositions according to the present invention are styrene; alpha-alkyl monovinylidene aromatic monomers including e.g., alpha-methylstyrene, alpha-ethylstyrene, alpha-methylvinyltoluene, alpha-methyl dialkylstyrenes,
• ring substituted alkyl styrenes including e.g., ortho-, meta-, and paravinyl toluene; o-ethylstyrene; p-ethylstyrene; 2,4-dimethylstyrene; p-tertiarybutyl styrene; etc.); ring-substituted halostyrenes including A - e.g., o-chlorostyrene, p-chlorostyrene, o-bromostyrene, 2,4-dichlorostyrene, etc.; ring-alkyl, ring- -halosubstituted styrenes including e.g., 2-chloro-4- -methylstyrene, 2,6-dichloro-4-methylstyrene, etc.; vinyl naphthalene; vinyl anthracene, and the like.
• the 0 alkyl substituents generally have 1 to 4 carbon atoms and may include isopropyl and isobutyl groups. If so desired, mixtures of such monovinylidene aromatic monomers may be employed. Typically, the monovinylidene aromatic monomer will constitute from 14 to about 75, 5 preferably from 50 to 70, weight percent of the MSAN-type interpolymer.
• Maleimide monomers suitably employed in the present invention include maleimide, N-alkylmaleimide 0 and N-aryl maleimide compounds.
• the aryl substituent may have one or more of the atoms replaced by other inert moieties such as halo or lower alkyl.
• Suitable N-aryl maleimides are disclosed in U.S. Patent 3,652,726.
• the aryl groups that may be present in the N-aryl maleimides include, for example, phenyl, 4- -diphenyl, 1-naphthyl, all the mono- and di-methylphenyl isomers, 2,6-diethylphenyl, 2-, 3- and 4-chlorophenyl, 4-bromophenyl and other mono- and di-halophenyl isomers, 2,4,6-trichlorophenyl, 2,4,6-tribromophenyl, 4-n- -butylphenyl, 2-methyl-4-n-butylphenyl, 4-benzylphenyl, 2-, 3- and 4-methoxyphenyl, 2-methoxy-5-chlorophenyl, 2-methoxy-5-bromophenyl, 2,5-dimethoxy-4-chlorophenyl, 2-, 3- and 4-ethoxyphenyl, 2,5-diethoxyphenyl, 4-phenoxyphenyl, 4-methoxycarbonylphen
• a preferred N-aryl maleimide monomer is N-phenylmaleimide. Mixtures of maleimide monomers may be employed. Suitably, the maleimide monomer is from 8 to 50, preferably from 8 to 36, weight percent of the MSAN-type interpolymer.
• the unsaturated nitrile monomers which may be included are acrylonitrile, methacrylonitrile, ethacrylonitrile, and mixtures thereof.
• the unsaturated nitrile is generally employed in the MSAN-type interpolymer in an amount of from 15 to 43, preferably from 20 to 25 weight percent based on the total weight of maleimide monomer, monovinylidene aromatic monomer and ethylenically unsaturated nitrile monomer employed in preparing the MSAN-type interpolymer containing those three monomers.
• additional monomers may be desirably included, in polymerized form, in the rubber-modified polymer compositions according to the present invention.
• additional monomers are conjugated 1,3 dienes (e.g., butadiene, isoprene, etc.); alpha- or beta-unsaturated monobasic acids and derivatives thereof (e.g., acrylic acid, methylacrylate, ethylacrylate, butyl acrylate,
• 2-ethylhexyl acrylate, methacrylic acid and the corresponding esters thereof such as methyl methacrylate, etc., acrylamide, methacrylamide and the like); vinyl halides such as vinyl chloride, vinyl bromide, etc.; vinylidene chloride, vinylidene bromide, etc.; vinyl esters such as vinyl acetate, vinyl propionate, etc.; dialkyl maleates or fumarates such as dimethyl maleate, diethyl maleate, dibutyl maleate, the corresponding fumarates, etc.
• Preferred examples of these additional monomers include Ci— alkyl methacrylates, including mixtures thereof.
• the amount of these monomers which may be included will vary as the result of various factors.
• the amount of such monomers employed will generally be less than 10 weight percent based on the total weight of the monomers employed in preparing the non-rubber, polymeric portions of the rubber-reinforced product of the invention.
• the various additional monomers can be incorporated into compositions according to the present invention in any or all of several ways.
• one or more of the additional monomers may be interpolymerized into the MSAN-type interpolymer.
• one or more of the additional monomers can be graft polymerized onto, and in the case of mass particles, polymerized and occluded within the rubber particles.
• one or more of the additional monomers can be otherwise polymerized into polymeric components which can be combined e.g., blended, into rubber-modified polymer compositions according to the present invention.
• the first graft copolymer comprises at least one type of rubber particle, produced in an emulsion polymerization process, the particle being grafted with an SAN or SAN-type interpolymer comprising polymerized therein from 10 to 60 weight percent of ethylenically unsaturated nitrile monomer and from 40 to 90 weight percent of monovinylidene aromatic monomer.
• the composition of the present invention comprises from 7 to 25 weight percent of the first graft copolymer.
• Certain preferred compositions of the invention comprise a greater amount of the second graft z, - copolymer than the first graft copolymer.
• one preferred embodiment of the invention employs 49 percent or less of the first graft copolymer based upon the total weight of the first and second graft copolymer.
• the emulsion rubber particle can have a 0 monomodal, but preferably has a bimodal, particle size distribution.
• the first graft copolymer may contain emulsion particles having different morphologies.
• the first graft copolymer advantageously comprises from 30 to 70 weight percent of the SAN or
• the first graft copolymer comprises from 35 to 55 weight percent emulsion rubber particle.
• the 30 rubber particle comprises polybutadiene rubber.
• the first graft copolymer preferably has a rubber particle size of from 0.05 to 0.65 ⁇ .
• Various substrate rubbers are utilizable as the emulsion particles.
• These rubbers include diene rubbers, ethylene propylene rubbers, ethylene propylene diene (EPDM) rubbers, acrylate rubbers, polyisoprene rubbers, halogen-containing rubbers and mixtures thereof as well as interpolymers of rubber-forming monomers with other copolymerizable monomers.
• the preferred rubbers for use in preparing said emulsion particles are diene rubbers or mixtures of diene rubbers, i.e., any rubbery polymers (a polymer having a second order glass transition temperature not higher than 0°C, preferably not higher than -20°C, as determined by ASTM Method Test D-746-52T) of one or more conjugated 1,3-dienes, e.g., butadiene, isoprene, piperylene, chloroprene, etc.
• Such rubbers include homopolymers and interpolymers of conjugated 1,3-dienes with up to an equal amount by weight of one or more copolymerizable monoethylenically unsaturated monomers, such as monovinylidene aromatic hydrocarbons (e.g., styrene; a ring-substituted alkylstyrene, such as o-, m-, and p-vinyl toluene or 2,4-dimethylstyrene, the ring-substituted ethylstyrenes, p-tert-butylstyrene, etc.; an alpha-alkylstyrene, such as alpha-methylstyrene, alpha-ethylstyrene, alpha- -methyl-p-methylstyrene, etc.; vinyl naphthalene, etc.); ring-substituted halo monovinylidene
• alkyl acrylates e.g., methyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, etc.
• alkyl methacrylates e.g., methyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, etc.
• the corresponding alkyl methacrylates acrylamides (e.g., acrylamide, methacrylamide, N-butyl acrylamide, etc.); unsaturated ketones (e.g., methyl vinyl ketone, methyl isopropenyl ketone, etc.); alpha- -olefins (e.g., ethylene, propylene, etc.); pyridines; vinyl esters (e.g., vinyl acetate, vinyl stearate, etc); vinyl and vinylidene halides (e.g., the vinyl and vinylidene chlorides and bromides, etc.); and the like.
• vinyl esters
• a preferred group of rubbers for use as the emulsion rubber particles are those consisting essentially of 70 to 100 percent by weight of butadiene and/or isoprene and up to 30 percent by weight of monomers selected from the group consisting of monovinylidene aromatic hydrocarbons (e.g., styrene) and unsaturated nitriles (e.g., acrylonitrile) or mixtures
• Particularly advantageous emulsion rubbery polymer substrates are butadiene homopolymer or an interpolymer of 90 to 99 percent by weight butadiene and 1 to 10 percent by weight of acrylonitrile and/or _,,- styrene.
• one of the rubber components 0 hereinafter referred to as the small particle component has a relatively small average particle size, the particles thereof advantageously having a volume average particle diameter of from 0.05 to 0.25 ⁇ and preferably a number average particle diameter of from 0.013 to 0.17 ⁇ . 25
• these small-sized particles are most conveniently prepared by emulsion polymerizing a mixture of rubber-forming monomers to form a dispersion of uniformly sized particles of the desired size, as is well known in the art. See, for example, U.S. Patents
• this component preferably has a volume average particle diameter of from 0.08 to 0.20 ⁇ , preferably with a number average particle diameter of from 0.02 to 0.13 ⁇ .
• Another rubber component to be included in this preferred rubber-modified composition is referred to as the large emulsion particle component.
• This component has a volume average particle diameter of from 0.35 to 0.65 ⁇ , preferably from 0.4 to 0.6 ⁇ .
• the particles of this component can be produced by agglomerating or coagulating emulsion- -produced dispersions of smaller rubber particles, either before, during or after the particles are grafted. See, for example, U.S. Patents 3,551,370; 3,666,704; 3,956,218; and 3,825,621 which teach suitable processes.
• a particularly desirable technique for the controlled agglomeration of the particles of an emulsion-prepared rubber in an aqueous dispersion is taught in U.S. Patent 4,419,496 entitled "Particle Agglomeration in Rubber Latices" by D. E. Henton and T. M. O'Brien.
• the aforementioned small and large emulsion rubber particles advantageously are employed in a weight ratio range of the former to the latter of from 0.33 to 4, and preferably from 0.4 to 1.
• a weight ratio range of the former to the latter of from 0.33 to 4, and preferably from 0.4 to 1.
• the use of the relatively larger particles in this component and/or the use of larger percentages of this component will usually result in better impact-resistance in the resultant polymer composition.
• the emulsion particle component advantageously makes up from 60 to 91 weight percent of the rubber in the present invention. However, it is preferred to employ from 60 to 88 weight percent, while from 60 to 70 weight percent is especially preferable. Within these ranges, the amount of emulsion particle rubber helps to control the tensile properties of the resultant polymeric composition. At constant rubber content, increasing the amount of emulsion particle rubber increases the tensile properties. Reducing the percentage of emulsion particle rubber will generally produce tougher resultant compositions with the loss of some tensile properties.
• the second graft copolymer comprises at least one type of rubber particle produced in a mass or mass- suspension polymerization process, the particle being grafted with an SAN or SAN-type interpolymer comprising polymerized therein from 15 to 36 weight percent of ethylenically unsaturated nitrile monomer and from 64 to 85 weight percent of monovinylidene aromatic monomer.
• the composition of the present invention comprises from 17 to 85 weight percent of the second graft copolymer.
• the mass rubber particle can have a polymodal particle size distribution, such as a bimodal distribution, but preferably has a monomodal particle size distribution.
• the mass rubber particle has a volume average particle diameter of less than 1 ⁇ .
• the rubber substrate used for the second graft copolymer advantageously is a diene homopolymer material, such as poly(1 ,3-butadiene) , or a block or random copolymer of at least 30, more preferably from 50 to 85, weight percent, 1 ,3-butadiene and up to about 70, more preferably from about 15 to 50, weight percent, of a monovinylidene aromatic compound, preferably styrene.
• This rubber substrate will, here again, typically have a second order glass transition temperature of 0°C or less, preferably -20°C or less.
• Preferred rubbers for use as the mass rubber particles are homopolymers of butadiene.
• the mass particle advantageously has a volume average particle diameter of less than 1 ⁇ , preferably from 0.15 to 0.95 ⁇ , and a number average particle diameter of from 0.1 to 0.45 ⁇ . More preferably, the volume average diameter of the particles of this component is from 0.4 to 0.9 ⁇ and the number average diameter thereof is from about 0.2 to about 0.4 ⁇ . Most preferably, the volume average particle size is from 0.4 to 0.69.
• the mass particle component advantageously makes up from 9 to 40 weight percent of the total rubber in the composition of the present invention, preferably from 12 to 40, and most preferably from 30 to 40 weight percent thereof. Particles sizes are measured using a commercially available Coulter Counter, by visual phase contrast microscopy or electron microscopy techniques supplemented according to methods well known in the art.
• the second graft copolymer have a total rubber content of 20 weight percent or less of the total weight of said graft copolymer, the remainder being an SAN or SAN-type interpolymer.
• Preferred second graft copolymers thus typically have a rubber content, on the basis of that graft copolymer per se, in the range of from 0.75 to 15, especially from 4 to 9, weight percent.
• compositions according to the present invention -18-
• Z. Z- preferably an SAN or SAN-type polymer.
• Such mass processes can be very satisfactorily employed to produce rubber particles having appropriate sizes for utilization in this component. See, for example, U.S. Patents 3,509,237 and 0 4,239,863 which teach suitable processes.
• compositions according to the present invention there will be dispersed therein in the form of particles, a total of from 8.5 to 13.5 5 weight percent rubber, based on the total rubber-
• the weight ratio of mass rubber to total rubber in the composition is from 0.09 to 0.4. More preferably, this ratio is from 0.12 to 0.4, and most preferably from 0.3 to 0.4.
• the particulate rubber dispersed in the polymeric matrix comprises at least two different components. It is generally preferred that the dispersed particulate rubber consist essentially of said particulate components.
• rubber particle component is meant a group of rubber particles of the
• the two main rubber particle types are (1) the occluded particles made in a mass-type process and (2) the solid, non-occluded particles made in an z - emulsion polymerization process.
• Each rubber component can then be characterized by the combination of the average size of the particles and the process by which they are formed.
• the average particle size of a rubber particle component will, unless 0 otherwise specified, refer to the volume average diameter of the group of particles making up the rubber component of particle type. In most cases, the volume average diameter of a group of particles is the same as the weight average.
• the average particle diameter measurement is typically made before any of the polymer is grafted thereto, while in the case of the mass particles, the size generally includes the polymer 0 grafted to the rubber particles and occlusions of polymer within the particles.
• the volume average diameters of emulsion particle groups having average particle diameters of less than about one micron can be conveniently determined, as can the number average diameters and the particle size distribution, by hydrodynamic chromatography (HDC). Hydrodynamic chromatography is explained in U.S. Patent No. 3,865,717, and is also discussed in the Journal of Colloid and Interface Science, V. 89, No. 1, pp. 94-106 (1982).
• the volume average diameters, number average diameters and particle size distributions can be determined by the analysis of
• the various _, £ - rubber particle components comprise particles having a range of sizes; the above analytical techniques indicate, however, that the particles of a particular rubber particle component generally have a fairly narrow range of particle sizes.
• the 20 ratio of the volume average particle diameter of a particle group to the number average particle diameter of the same particle group is generally in the range of from 1 to 3.5.
• the aforementioned rubber ingredients may contain up to 2 percent of a cross-linking agent, based on the weight of the rubber-forming monomer or monomers, cross-linking may present problems in dissolving the rubber in the monomers for the graft
• a cross-linking agent can be any of the agents conventionally employed for cross-linking diene rubbers, for example, divinylbenzene, diallyl maleate, diallyl fumarate, diallyl adipate, allyl acrylate, allyl methacrylate, diacrylates and dimethylacrylates of polyhydric alcohols (e.g., ethylene glycol dimethylacrylate, etc.), and the like.
• ABS-type compositions may also be desirable to include in the present ABS-type compositions amounts of other polymers and/or copolymers such as polymers and/or copolymers of phenylene oxide, polycarbonates and polyester polycarbonates.
• the desired polymerizable monomers are combined with the preformed rubber substrate and the monomers are then polymerized to chemically combine or graft at least a portion of the forming polymer upon the rubber substrate.
• the ratio of monomers to rubber substrate and the polymerization conditions it is possible to achieve both the grafting of the desired amount of polymer onto the rubber substrate and the polymerization of ungrafted polymer to provide all or a portion of the matrix at the same time.
• Free radical emulsion polymerization can be used to produce a latex emulsion which is useful as the base for emulsion polymerization of the graft polymer. See, for example, U.S. Patent 4,243,765.
• the various techniques suitable for producing the polymeric components of the present invention are well known in the art. Examples of these known polymerization processes include mass, mass-solution, mass-suspension, suspension and emulsion polymerization processes as well as other modification and/or combinations of such processes. See, for example, U.S.
• the same reaction that is grafting homo- or interpolymer onto one or more of the rubber components can advantageously be used to produce all or part of a corresponding ungrafted homo- or interpolymer for the matrix portion. It should be noted that any production of grafted polymer, in most cases, inherently produces small amounts of ungrafted (i.e. matrix) polymer.
• small emulsion particles and large emulsion particles are grafted at the same time with monovinylidene aromatic and ethylenically unsaturated nitrile monomers and produce, also at the same time, a small amount of ungrafted SAN or SAN-type interpolymer;
• the grafting of the mass particles is done with the same or different monovinylidene aromatic and ethylenically unsaturated nitrile monomers in a different, separate process and also produces a portion of the total ungrafted SAN or SAN-type interpolymer desired for the matrix of the final composition;
• the balance of the ungrafted MSAN-type interpolymer desired as the matrix of the rubber-modified polymer composition hereof is produced separately; and (4) the indicated ingredients are then combined to form the subject polymer compositions.
• the separately produced MSAN-type interpolymer is produced in a mass or mass-solution type of polymerization process.
• the matrix portion of the present invention comprises: (1) MSAN-type interpolymer; (2) other comonomers interpolymerized into the MSAN-type interpolymer; (3) additional non-elastomeric polymeric material combined therewith; (4) ungrafted, unoccluded polymer produced during the grafting of the emulsion particles; (5) ungrafted, unoccluded polymer produced during the grafting of the mass particles; and/or (6) other filler-type materials.
• the weight average molecular weight (Mw) of all the matrix (ungrafted) polymer, from all sources typically is from 40,000 to at least 300,000, preferably from 70,000 to 200,000.
• the Mw's of the ungrafted, unoccluded polymer included in the present rubber-modified polymer compositions which amounts of polymer: (1) can be produced during the grafting of the emulsion particles; (2) can be produced during the grafting of the mass particles; (3) are the MSAN-type polymer; and/or (4) can be from other sources of ungrafted matrix polymer, will average out to be within the desired range.
• the composition has a Vicat softening point of at least 104°C (DIN-B), preferably at least 112°C.
• the impact strength of the compositions of the present invention, as determined by the Charpy method are advantageously at least 7, and preferably is at least 9 kJ/m .
• the tensile strength at yield is advantageously at least 50 N/mm 2 ' and preferably is at least 55 N/mm .
• the compositions of the present invention advantageously have an elastic modulus of at least 2400 MPa, and preferably at least 2500 MPa.
• weight percentages of the three polymeric components of the invention i.e. the MSAN-type polymer and the first and second graft copolymers, are based upon the total weight of these components.
• the present invention is further illustrated by reference to the following specific examples, preparations, and comparative experiments. All parts and percentages are by weight unless otherwise explicitly indicated.
• Various standard test methods are used to evaluate the physical properties of the various polymer compositions.
• the notched Izod impact strength values are determined according to ISO 180 4a.
• Tensile strengths at yield and rupture (Ty and Tr, respectively) and percent elongation are determined according to DIN 53455-6-3.
• Melt flow rate (MFR) values are determined according to DIN 53735-U. Vicat heat distortion is determined according to DIN 53460, Condition B.
• the Charpy impact is determined according to DIN 53453.
• the elastic modulus is determined according to DIN 53457.
• the Comparative Experiments are not embodiments of the present invention.
• a mixture of 8 percent N-phenylmaleimide, 52 percent styrene, 20 percent acrylonitrile and 20 percent ethylbenzene is fed to an SAN coil reactor at a temperature between 140 and 146°C.
• a solution of a radical-forming organic compound is supplied to the reactor.
• the prepolymer of 40 to 70 percent solids is devolatilized by applying vacuum.
• a mass particle constituent is prepared by ..- dissolving polybutadiene (BUNA HX529C brand rubber available from Bayer A.G.) in a mixture of styrene, acrylonitrile and ethylbenzene, then polymerizing the monomers while agitating and/or otherwise shearing to achieve the desired rubber particle size.
• BUNA HX529C polybutadiene
• some forming interpolymer is grafted to the rubber while some does not graft but forms matrix interpolymer.
• varying amounts of matrix interpolymer can be formed (in addition to the grafted portion) depending on 5 the amounts of monomers supplied.
• aqueous latex containing particles of rubber is heated while the graftable monomers (styrene and acrylonitrile), mercaptan, persulfate initiator, and emulsifying agent are supplied.
• the latex, containing the SAN-grafted rubber particles as well as some ungrafted SAN is freeze coagulated, thawed, centrifuged, then air dried to reduce the water content below 1 percent in the resultant powdery polymer composition.
• This procedure describes the preparation of monomodal emulsion ABS.7 as well as the preparation of the small particles in bimodal emulsion ABS.6 and bimodal emulsion ABS.8.
• the bimodal emulsion ABS materials are prepared by adding, prior to the addition of the graftable monomers, about 0.34 weight percent based on the total weight of rubber of an agglomerating agent to the starting aqueous latex of the proceeding paragraph.
• the agglomerating agent consists of polybutadiene core with a shell of ethylacrylate-methacrylic acid (92/8) copolymer. A portion of particles agglomerate to give a bimodal particle size distribution of large particles and small particles. This latex is then grafted and recovered in the same manner described in the proceeding paragraph.
• Mass ABS.3, and 60 parts MSAN.1 are dry blended.
• the resulting blend is then compounded into a homogeneous melt on a compounder and is extruded into strands which are then pelletized.
• the pellets are injection molded into standard test bars having the blended composition.
• Example 1 The procedure of Example 1 is repeated using 15 parts Emulsion ABS.6, 50 parts Mass ABS.3, and 35 parts MSAN.1. Further characteristics of the blended composition and results of physical testing are given in Table 1.
• Example 2 The procedure of Example 1 is repeated using the blend components in amounts as specified in Table 2. Further characteristics of the blended composition and results of physical testing are given in Table 2.
• compositions of Examples 3-5 exhibit high heat properties as well as unexpectedly high tensile strengths.
• Comparative Example 6 is outside the desired range of the mass rubber/total rubber ratio and consequently has an unacceptably low impact value.
• Comparative Experiment 7 contains no mass ABS and possesses a Charpy value of 4.2, which is too low, despite the fact that the total rubber level is comparable with that of Example 5.
• Example 1 The procedure of Example 1 is repeated using the blend components in amounts as specified in Table 3. Further characteristics of the blended composition and results of physical testing are given in Table 3.
• ABS.6 20 15 15 10 20 45
• E-Mod. 2445 2550 2615 2665 2735 2990 1845
• Examples 8-12 are embodiments of the invention exhibiting high Vicat softening temperatures with unexpectedly high tensile properties. Comparative
• Example 13 contains 14.6 percent rubber which is above the upper limit for the rubber level as specified in this invention. Consequently, although the impact is high, the Young's Modulus is too low. Comparative
• Mw indicates weight average molecular weight of the MSAN components) of the blend.
• the data in Table 4 demonstrate the effect of the molecular weight of the MSAN with regard to the retention of reasonable (i.e. Charpy >7) impact performance at equivalent tensile properties.
• Charpy >7 i.e. Charpy >7
• Example 1 The procedure of Example 1 is repeated using the blend components in amounts as specified in Table 5. Further characteristics of the blended composition and results of physical testing are given in Table 5.
• MVS methacrylate-butadiene-styrene
• Paraplex 3607 from the Rohm and Haas Company. (Paraplex is a trademark of the Rohm and Haas 30 Company).
• the emulsion ingredient in the blend system has rubber particles made from essentially 100 butadiene. However, as is illustrated by Examples 20 and 22, emulsion rubber particles consisting of 93 percent butadiene with 7 percent styrene are within the scope of the invention. The use of monomodal emulsion ABS is also shown in Example 20. The use of bimodal mass
• ABS is shown in Example 21.
• Alternative impact modification packages such as mixtures of emulsion
• Example 23 ABS with MBS are shown in Example 23 to give blends with properties in the desired ranges.
• a rubber particle size of 1.11 micron was found to be above the upper limit for maintaining good tensile properties as is illustrated by Comparative Experiment 19.

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