WO1993021274A1 - Multilayer core-shell polymer compositions as toughener for thermosets and thermoplastics - Google Patents

Multilayer core-shell polymer compositions as toughener for thermosets and thermoplastics

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Publication number
WO1993021274A1
WO1993021274A1 PCT/US1993/002993 US9302993W WO1993021274A1 WO 1993021274 A1 WO1993021274 A1 WO 1993021274A1 US 9302993 W US9302993 W US 9302993W WO 1993021274 A1 WO1993021274 A1 WO 1993021274A1
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WO
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Patent type
Prior art keywords
shell
composition
acrylate
core
meth
Prior art date
Application number
PCT/US1993/002993
Other languages
French (fr)
Inventor
Changkiu K. Riew
Original Assignee
The B.F. Goodrich Company
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    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08LCOMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L51/00Compositions 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
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08FMACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F285/00Macromolecular compounds obtained by polymerising monomers on to preformed graft polymers
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08LCOMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L63/00Compositions of epoxy resins; Compositions of derivatives of epoxy resins

Abstract

The present invention relates to a multilayer core-shell polymer composition. The composition in free flowing particulate form may be used as a toughener for thermoset material. The toughener comprises at least three layers: a plastic core, an elastomer inner shell, and a plastic outer shell.

Description

MULTILAYER CORE-SHELL POLYMER COMPOSITIONS AS TOUGHENER FOR THERMOSETS AND THERMOPLASTICS

FIELD OF THE INVENTION

The present invention relates to a multilayer core-shell polymer composition comprising at least three layers. The composition is free from any crosslinking and grafting agents. The core-shell polymer composition is free flowing and acts as a toughener when blended in thermosets or thermoplastics. The composition is com¬ prised of a plastic core, a thin elastomeric inner shell, and a plastic outer shell.

BACKGROUND OF THE INVENTION

A method of improving the crack or impact resis¬ tance of plastic materials is to add or produce in situ a rubber or plastic second phase in discrete particulate form. The use of a small amount of a reactive liquid polymer, such as a carboxyl-, amine-, acrylic, mercaptan-, or hydroxyl-terminated butadiene-acrylonitrile copolymer to modify a thermoset resin, such as epoxy, unsaturated polyester, bismaleimide, cyanate polyester, phenolic resins, is known in the art to lead to a more crack- resistant thermoset resin. However, it is known that stiffness may be lost depending on the chemical structure and amount of the added reactive liquid polymer. For a thermoset resin toughened with a reactive liquid polymer, however, one has little control over sizes, composition, and rigidity of domains, chemical bonding at the inter- phase, etc. Those factors are controlled by (a) type and reactivity of functional groups of the reactive liquid polymer, (b) compatibility of the toughener in epoxy resin, (c) type and molecular weight of the backbone of the toughener, (d) type and amount of a cure agent, and (e) cure temperatures. "Micromechanical Analysis of a Model for Partic¬ ulate Composite Material with Composite Particles - Survey of Craze Initiation," Polymer Engineerincr and Science. 1978, Vol. 18, No. 10, Ricco et al, discloses a quanti- tative assessment of the effect of structural heterogene¬ ity of rubber particles on mechanical factors. Ricco showed that distributions of the stress and strain pertur¬ bations (around a glassy sphere) in the surrounding plastic matrix produced by a rubber-coated spherical hard particle closely approximated those produced by a solid rubber particle, until the rubbery coating on the surface of hard particle became very thin (about 1/10 of the total diameter of the core particle) . The results provide a theoretical explanation of what has been observed with a high impact polystyrene having glassy plastic-styrene particles occluded within butadiene-rubbery particles in a styrene matrix - a large volume fraction of occluded glass could exist within the rubber particle without impairing its toughening effect. This means that a glassy plastic or hard inorganic filler particle having a thin rubber coating can behave like a solid rubber particle in toughening efficiency. The toughening effect of the thin film of rubber is due mainly to energy absorbing plastic flow induced during crack propagation. The impact modification or toughening of a brittle plastic using discrete solid rubber particles is conventional. The prior art generally teaches that for multi-layer polymeric tougheners, the rubber content should be increased until load bearing properties become unacceptable. The present invention uses a thin elastic inner shell over a plastic core, both of which behave like a total rubber particle but retain load bearing stiffness of the particle as well as the matrix to be toughened. The present invention therefore provides a toughener which improves impact resistance without significantly reducing stiffness. Prior to the present invention, multi-layer composites were generally crosslinked to increase green strength, brittleness, and to improve their ability to survive in a high shear mixing process. Journal of Material Science, 1986, Vol. 21, Yee et al showed that the toughness of CTBN modified epoxy resin generally increased as the molecular weight between the crosslinks was in¬ creased. The present invention is free from crosslinking within and between the layers, in order to maximize linear molecular weight.

Preprint, 29th Annual Conference, Reinforced Plastics/Composites Institute, The Society of the Plastics Industry, ID, 4 pp (1974) , Siebert et al reported latexes with one-layer elastomeric polymer improved toughness by modifying an epoxy resin. The latex comprised reactive (carboxyl containing) or non-reactive nitrile rubber particles in water. Water was vacuum distilled after blending the latex with the epoxy resin. This toughening technology is using preformed elastomer particles in latex-form for better control over size, shape, and composition. However, distribution of the particles evenly throughout the matrix resin and prevention of the particles from agglomeration or aggregation was a problem. If the agglomerates or aggregates are larger than optimum sizes, they may act as flaws rather than toughening agents. The present invention is substantially free from agglomeration. In "Rubber-Toughened Plastics",

C. K. Riew, Editor., Advances Chemistry Series, American Chemical Society, Washington, DC, 1989, Vol. 222, p. 15, Echte reviewed a toughening technology of free flowing, reactive or non-reactive powders used in toughening various thermoplastics. For example, multi-layer core- shell polymers (or overpoly ers) are normally made from emulsion polymerization followed by spray-drying or are dried after coagulation.

U.S. Patent No. 3,251,904 to Souder et al relates to solid, thermoplastic, polymeric products from the sequential polymerization of alkyl methacrylate with polyalkyl acrylates and to high impact resistance materi¬ als resulting from blends of such products with other polymeric materials, especially polyvinyl chloride. U.S. Patent No. 3,655,825 to Souder et al relates to solid, thermoplastic, polymeric products resulting from the polymerization of lower alkyl esters of acrylic and methacrylic acid and to high impact-resistant materials which result from blends of such products and other polymeric materials, particularly polymers and copolymers of vinyl chloride. Crosslinking monomers are utilized.

U.S. Patent No. 3,793,402 to Owens relates to an impact resistant thermoformable composition having im- proved stress whitening behavior comprising a blend of a thermoplastic polymer and a multi-stage, sequentially produced polymer characterized by a non-elastomeric hard stage, an intermediate elastomeric stage, and a relatively hard stage. U.S. Patent Nos. 3,808,180 and 3,843,753 to

Owens relates to rigid thermoplastics such as acrylic polymers and vinyl halide polymers which are modified to impart high impact resistance.

U.S. Patent Nos. 3,859r384 and 3,859,389 to Carty et al relate to acrylic modifiers for vinyl halide polymers having superior mill roll release at high temper¬ ature and resistance to "plate out," obtained by modifying the polymers with a multi-phase based acrylic composite polymer having a first non-crosslinked phase and a final, rigid thermoplastic phase polymerized in the presence of the first phase.

U.S. Patent No. 4,026,970, to Backderf et al relates to a three layer (hard-soft-hard) , particulate core-shell polymers. The polymer is used to toughen unsaturated polyester compounds.

U.S. Patent No. 4,086,296 to Carty et al relates to blends of thermoplastic polymers and a multi-phase acrylic composite polymer comprising a non-crosslinked phase, and a final rigid thermoplastic phase polymerized in the presence of said first phase. The core polymer has a very low molecular weight, that is less than 50,000, and contained no suggestions of imparting improved impact resistance.

U.S. Patent No. 4,096,202 to Farnham et al relates to a blend of a polyester and an impact modifier which is a multi-phase composite interpolymer comprising a crosslinked acrylic first stage and a final rigid thermoplastic stage.

U.S. Patent No. 4,299,928 and 4,378,449 to Witman relate to polycarbonates having improved impact performance comprising a blend of a polycarbonate resin and a C.^ to Cg acrylic rubber interpolymer composite.

International SAMPE Technical Conferences, 18th Annual Meeting, 1986, Shimp et al modified polycyanurates with engineering thermoplastics, such as polyetherimide, polyacrylate or polysulfone with improved toughness. U. S. Patent No. 4,778,851, to Henton et al, and

SAMPE Series, 1991, Vol. 36, Sue et al, reported toughened epoxy resin with core (polybutadiene-styrene-acryloni- trile) - shell (polystyrene-acrylonitrile-glycidyl methac- rylate or ethyl acrylate/methacrylic acid) at 10 weight percent level in liquid epoxy resin cured with 5 weight percent of piperidine. It supposed to contain reactive groups on the shell, but the author did not elaborate which functional groups or reactivity.

U.S. Patent No. 4,883,841 to Riew et al relates to polycarbonates which are blended with an impact modifi¬ er to improve the impact resistance thereof. The impact modifier is a multiple phase polymer system prepared by subsequent multiple stage polymerizations. The first phase which constitutes from about 50 percent to about 90 percent by weight of the multiple phase impact modifier is generally an elastomer such as an alkyl aerylate wherein the alkyl portion has from 2 to 18 carbon atoms. The second phase polymer is generally a plastic type compound such as a vinyl substituted aromatic, an alkyl methacry- late, or an alkenyl nitrile compound.

U.S. Patent No. 4,894,414 to Yang et al disclos- es rubber modified cyanate ester resin including dispersed resin insoluble rubber particles grafted with resin soluble polymer.

U.S. Patent Nos. 4,690,988 and 5,505,532 to

Hoffman et al, disclose a dispersion polymerization of 2-ethylhexyl acrylate in epoxy resins. The epoxy resin, containing the acrylic rubber domains, was cured with a polyamide to give toughened resin.

Polymeric Materials: Science and Engineering,

Vol. 63, Jin et al, reported that the addition of parti- cles of an acrylic polymer microgel (core-shell polymers with reactive carboxyl groups on the shell) improved the toughness of an epoxy resin.

Polymeric Materials: Science and Engineering,

Vol. 63, Lovell et al made two-(rubbery core and plastic shell), three-(plastic core, rubbery inner-shell, and plastic outer shell) and 4-layer (rubbery core, first plastic inner shell, second rubbery inner shell, and plastic outer shell) core-shell polymeric particles by sequential emulsion polymerization. The rubbery layers consist of crosslinkedpoly((n-butyl acrylate)-co-styrene) and the plastic layers consist of poly((methyl methacry- late)-co-(ethyl acrylate)) and the first inner plastic shells were crosslinked. These polymers were used to toughen polymethylmethacrylate.

SUMMARY OF THE INVENTION

The present invention relates to a multilayer core-shell polymer composition comprising at least three layers. Additional alternating plastic and elastic shells can be added to produce a component having more than three layers. The layers are composed of a plastic core, an elastomeric inner shell, and a plastic outer shell. The outer shell, optionally, contains reactive functional groups. The composition is substantially free from any crosslinking or grafting agents, and preferably, complete- ly free of such agents. The composition is a free flowing particulate material which acts as a toughener or impact modifier for thermoset or thermoplastic materials. The multilayer core-shell polymer composition of the present invention have been found to exhibit unexpectedly improved crack and/or impact resistance with good heat stability when the multilayer core-shell polymer composition is used to toughen epoxy resin.

DETAILED DESCRIPTION

. Multilayer core-shell polymer compositions for thermosets are made from at least a three layer composi¬ tion.

The core and the outer shell materials are generally plastic and may have the same or different composition. The plastic polymer is generally a rigid free flowing powder, granule, or pellet, at room tempera¬ ture, and has a glass transition temperature (TCT) of at least 20°C, desirably at least 30°C. The monomers for each layer do not include any crosslinking or grafting agents.

Various monomers and comonomers can be utilized to form the plastic polymer core and outer shell. Such monomers include any free radical emulsion polymerizable monomer such as the various alkyl methacrylates, wherein the alkyl portion has from about 1 to about 3 carbons atoms, with specific examples including methylmeth- acrylate, t-butylmethacrylate, propyl ethacrylate, and the like, with methylmethacrylate being preferred. Another group of monomers are the various vinyl substituted aromatics having from 8 to about 12 carbon atoms, and preferably from about 8 to about 10 carbon atoms, with specific examples including styrene, styrene with ring substituted methyl or chloro groups, alpha-methyl styrene, and the like, with styrene and alpha-methyl styrene being preferred. Another suitable group of plastic-forming monomers is vinyl nitrile compound and derivatives thereof having up to about 12 carbon atoms, such as acrylonitrile or methacrylonitrile. Still another group of monomers are the various mono-olefins having from 2 to 6 carbon atoms such as 1-butylene, 2-butylene, and the like. Desirably, copolymers of the above monomers are utilized to form the plastic polymer with specific examples including the copolymers made from styrene-acrylonitrile, styrene- methylmethacr late-acrylonitrile, methylmethaσrylate- acrylonitrile, styrene-methylmethacrylate, and the like. Advances in Chemistry Series, Vol 154, Riew et al described the importance of covalent chemical bonding and/or compatibility between the toughening domains and matrix resin to maximize toughness. It is, thus, desirable to utilize small amounts of comonomers with reactive functional groups in the outer shell in order to improve adhesion by means of reactivity at the interface between the toughener particles and matrix resin which is to be toughened. Such optional, but desirable comonomers are utilized in an amount of less than 50 percent by weight and desirably less than about 30 percent by weight based upon the total weight of the outer plastic shell. Such reactive comonomers may contain mono-, or di-acid (an anhydride which can give a diacid may be used) , hydroxyl, mercaptan, amine, or epoxy groups. Examples of carboxyl containing monomers are itaconic acid or anhydride, maleic acid or anhydride, fumaric acid, allyl acetic acid, (meth)acrylic acid. Examples of other reactive monomers are hydroxyethyl (meth)acrylate, hydroxyl-ethoxyethyl (meth)acrylate, hydroxyl-ethoxyethyl acrylate, glycidyl (meth)acrylate, and the like.

Reactive macromers with a molecular weight of greater than 100 and long chain polymers such as α-carbox- yl alkyl (meth)acrylate, α-hydroxyl-polyether (meth)- acrylate, α-hydroxyl-polycarbonate (meth)acrylate, and α- hydroxyl-polyester (meth)acrylate may also be used. Commercial α-hydroxyl-polyester (meth)acrylate is manufac- tured by Union Carbide and sold under the trademark TONE M-100®.

In order to improve compatibility at the inter¬ face between the outer-shell and matrix resin, various monomers can be used to increase Van der Waals forces, hydrogen bonding and/or other intermolecular interactions. The choice of monomers or comonomers for the outer-shell of the tougheners are decided based on the resin to be toughened. For example, in thermoplastics, if the resin is polystyrene, the outer-shell may consist of mainly styrene. For epoxy resins, alkyl acrylates such as methyl(meth)acrylate, ethyl(meth)acrylate, hydroxyethyl-

(meth)acrylate, hydroxyl-ethoxy-ethyl(meth)acrylate, hydroxyl-ethoxyethyl acrylate, glycidyl(meth)acrylate, and the like, (meth)acrylonitrile, and any monomers containing radicals of polyether, polyester, polyamide, polyimide, polyarylethers, polyarylesters, styrene maleic anhydride, and the like, which are mostly polar groups, can be used.

On a weight basis, the core can represent from about 10 percent to about 90 percent, more desirably from about 30 percent to about 90 percent and preferably from about 50 percent to about 90 percent, of the multilayer core-shell polymer composition.

The outer shell may be made from different polymeric materials from those used for the core. The outer shell should substantially cover the elastomeric inner shell and can represent from about 5 percent to about 30 percent and preferably less than 20 percent of the multilayer core-shell polymer composition on a weight basis. The elastomeric inner shell or phase of the multilayer core-shell polymer composition has a glass transition temperature below about 10°C, and preferably below about 0°C. Examples of monomers utilized to make the elastomer phase are various alkyl acrylates having the formula

A 0

CH2=C—C-OB where A is an alkyl having from 1 to 3 carbon atoms, or preferably a hydrogen atom, and B is an alkyl having from 4 to 20 carbon atoms and preferably from 4 to 16 carbon atoms. Examples of specific compounds include ethyl acrylate, butyl acrylate, pentyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, stearyl acrylate, lauryl acry¬ late, and the like, with 2-ethylhexyl acrylate being preferred. Optionally, plastic forming monomers, such as styrene, acrylonitrile, and the like can be utilized as comonomers with the elastomer forming monomers, from about 0 to about 25 percent by weight and preferably from about 0 to about 20 percent by weight, based upon the total amount of the elastomer forming monomers. The elastomers of the present invention have a high molecular weight as from about 5,000 or greater and preferably from about 10,000 or greater.

Other suitable monomers which may be utilized to make the elastomeric inner shell include monomers contain- ing elastomer forming radicals, such as fluoros, siloxan- es, ethers, esters, and the like.

Some of the requirements for high performance thermoset resins are high temperature or prolonged out door serviceability, such as oxidative and ultraviolet radiation stability. The backbone of the elastomer phase is therefore generally saturated because any unsaturation would tend to cause poor stabilities.

The amount of elastomeric material used for the inner shell depends primarily on the particle size and the desired properties of the composition. The amount, thus, may be from about 5 percent to about 80 percent, more desirably from about 5 percent to about 50 percent, and preferably from about 5 to 30 percent of the total weight of the composition. A thin film of the elastomer layer is more effective in retaining stiffness or compression strength properties. Conventional free flowing core-shell tougheners for thermoplastics are designed to maximize elastomer content in the composition for better impact resistance. The maximum elastomer content, however, may reduce stiffness.

The ratio of the elastomer inner-shell layer thickness to the total diameter of core plus inner-shell is important and should be determined based on the polymer and/or matrix resin used. A ratio of about 1:200 to about 1:2 is desirable, and a ratio of about 1:100 to about 1:2 is preferred. The particle sizes of the impact modifier and their distribution in the matrix resin are important since they affect the toughness properties produced when blended in various thermosets or thermoplastics. Generally, the multiple phase impact modifiers of the present invention have a particle size of from about 5 nanometers to about 150 micrometers. The particle size must be determined for the particular resin which is to be toughened. In gener¬ al, the type of matrix resin, the type and amount of cure agents, and the cure temperature determines the ductile- brittle nature of the cured resin. The amount of impact modifier utilized per 100 parts by weight of thermoset resin or thermoplastic resin is from about 1 to about 40 parts by weight and preferably from about 1 to about 30 parts by weight depending on the thermoset resin or thermoplastic resin to be toughened.

The polymerization of the elastomer polymer forming monomers, as well as the plastic polymer forming monomers of the present invention, can generally be carried out according to any conventional process. However, sequential emulsion polymerization is typically preferred to produce core and multiple shell type composi¬ tions. Sequential suspension polymerization yields relatively large particles and may be preferred for toughening a particular xesin.

The polymers of the present invention were pre¬ pared by sequential emulsion polymerization procedures using a multiple stage technique. In general, the first hard plastic phase or core was formed, then the elasto¬ meric inner shell was formed, and finally the hard plastic phase or outer shell was formed. The monomers and/or comonomers for each layer were emulsified in water (mono- er emulsions) and stored in separate storage tanks. In a reactor, an emulsifier was mixed in water then heated to a desired temperature. The polymerization initiator solution was freshly prepared and added to the reactor solution. The first layer monomer emulsion (core) was metered into the reactor at a desired set rate, and poly¬ merized by heating and mixing the emulsion in a well known manner until the monomers were substantially depleted and a first phase polymer was formed. Monomers of the second, and each subsequent additional phase, were then separately added with appropriate additives, e.g. supplementarily booster initiator solution, so that the desired polymer¬ ization of each phase subsequently occurred until the sub¬ stantial exhaustion of the monomers for each phase. In each phase, subsequent to the first, the amounts of the initiators, if any, were maintained at a level such that the polymerization occurred at or near the surface of existing particles, and no substantial number of new particles or seeds were formed in the .emulsion. The elastomeric phase was generally soft whereas the plastic phase was generally hard and, hence, was free-flowing after evaporation of water. As noted above, it is an important aspect of the present invention that the elastic phase, as well as the plastic phase, were non-crosslinked in order to maximize linear molecular weight. That is, there were no crosslinking or grafting monomers added.

The polymerization reactions can be initiated by free radical initiator systems. Examples of such initia- tors include the organic peroxides, such as benzoyl peroxide, substituted benzoyl peroxides, acetyl peroxides, lauryl peroxide, t-butyl hydroperoxide, di-t-butyl perox¬ ide, peresters such as t-butylperoxypivalate, azo-type initiators such as azo-bis-isobutylonitrile, persulfates such as sodium, potassium or ammonium persulfate, and peroxyphosphates such as sodium, potassium, or ammonium peroxy phosphate and radiation such as ultraviolet light. Redox initiators are generally a combination of a hydro- peroxide such as hydrogen peroxide, t-butyl-hydroperoxide, cumene hydroperoxide, di-isopropylbenzene hydroperoxide, and the like, with a reducing agent such as sodium, potassium, or ammonium bisulfite, etabisulfite, or hydrosulfite, sulfur dioxide, hydrazine, ferrous salts, ascorbic acid, sodium formaldehyde sulfoxylate, and the like, as are well known in the art.

Examples of emulsifiers or soaps suited to polymerization processes of the present invention include alkali metal and ammonium salts of alkyl, aryl, alkaryl, and aralkyl sulfonates; sulfates; polyether sulfates; fatty acids; complex organophosphoric acids; as well as ethoxylated derivatives of fatty acids, esters, alcohols, amines, amides and alkyl phenols.

The multilayer core-shell polymer composition of the present invention can be blended in a conventional manner with various thermoplastic or thermosetting materi¬ als to improve the impact resistance thereof.

Epoxy resins useful in this invention include a wide variety of epoxy compounds. Typically, the epoxy compounds are epoxy resins which are also referred to as polyepoxides. Polyepoxides useful herein can be monomeric (e.g., the diglycidyl ether of bisphenol A, novolac-based epoxy resins, and tris-epoxy resins) , higher molecular weight advanced resins (e.g. the diglycidyl ether of bisphenol A advanced with bisphenol A) or polymerized unsaturated monoepoxides (e.g., glycidyl acrylates, glycidyl methacrylate, allyl glycidyl ether, etc.) to homopolymers or copolymers. Most desirably, epoxy com¬ pounds contain, on the average, at least one pendant or terminal 1,2-epoxy group (i.e. vicinal epoxy group) per molecule. Examples of useful polyepoxides include the polyglycidyl ethers of both polyhydric alcohols and polyhydric phenols; polyglycidyl amines, polyglycidyl amides, polyglycidyl imides, polyglycidyl hydantoins, polyglycidyl thioethers, epoxidized fatty acids or drying oils, epoxidized polyolefins, epoxidized diunsaturated acid esters, epoxidized unsaturated polyesters, and mixtures thereof. Numerous polyepoxides prepared from polyhydric phenols include those which are disclosed, for example, in U.S. Patent No. 4,431,782. Polyepoxides can be prepared from mono-, di- and tri-hydric phenols, and can include the novolac resins. Polyepoxides can include the epoxidized cycloolefins; as well as the polymeric polyepoxides which are polymers and copolymers of glycidyl acrylate, glycidyl methacrylate and allylglycidyl ether. Suitable polyepoxides are disclosed in U.S. Patent Nos. 3,804,735; 3,892,819; 3,948,698; 4,014,771 and 4,119,609; and Lee and Neville, Handbook of Epoxy Resins. Chapter 2, McGraw Hill, NY (1967).

While the invention is applicable to poly- epoxides, generally preferred polyepoxides are glycidyl polyethers of polyhydric alcohols or polyhydric phenols having weights per epoxide group of 150 to 2,000. These polyepoxides are usually made by reacting at least about two moles of an epihalohydrin or glycerol dihalohydrin with one mole of the polyhydric alcohol or polyhydric phenol, and a sufficient amount of a caustic alkali to combine with the halohydrin. The products are character¬ ized by the presence of more than one epoxide group, i.e. , a 1,2-epoxy equivalency greater than one. The polyepoxide may also include a minor amount of a monoepoxide, such as butyl and higher aliphatic glycidyl ethers, phenyl glycidyl ether, or cresyl glycidyl ether, as a reactive diluent. Such reactive diluents are commonly added to polyepoxide formulations to reduce the working viscosity thereof, and to give better wetting to the formulation. As is known in the art, a monoepoxide affects the stoichiometry of the polyepoxide formulation and adjustments are made in the amount of curing agent and other parameters to reflect that change.

In the curing of polyepoxides, the choice of curing agent can influence the cure rate, the exotherm and resultant properties of the finished product. Curing agents or hardening agents and their influence are known in the literature as, for example, in the book, Handbook of Epoxy Resins, (supra) and in Chemical Reactions of Polymers. Interscience Publishers, New York, pages 912- 926, (1967) and in other reference works. Some of these influences are illustrated in Modern Plastics Encyclope¬ dia, pages 33-34, (1982-1983).

Curing agents conventionally used for curing epoxy resin compositions include aliphatic and aromatic primary amines such as di(4-aminophenyl)sulfone, di(4- aminophenyl) ethers, 2-2-bis(4-aminophenyl)propane, aliphatic and aromatic tertiary amines such as dimethyl- aminopropyl-amine and pyridine, boron trifluoride complex¬ es, inidazoles such as 2-ethyl-4-methyl imidazole, hydra- zides such as aminodihydride, guaridines such as tetra- methyl guanidine, and dicyandiamide.

The multilayer cure-shell polymer composition of the invention can also be advantageously used to toughen epoxy resin compositions incorporating a substituted fluorene diol component, a substituted fluroene diepoxide component or a mixture thereof as disclosed in European Patent Application No. 88312242.6 hereby incorporated by reference herein. It can also be used to toughen an epoxy resin composition incorporating a substituted fluorene diamino component as disclosed in U.S. Patent No. 4,684,678 hereby incorporated by reference herein. Another suitable epoxy matrix which can be used advanta- geously with the core-shell composition includes an elastomer-modified epoxy resin, such as disclosed in European Patent Application No. 91200622.8 hereby incorpo¬ rated by reference herein, obtained for example by dis- persing a carboxy-functionalized hydrogenated diolefin- monoalkenylarene block copolymer in a liquid epoxy resin, contacting the resulting elastomer-dispersed epoxy resin composition with a polyhydric phenolic component in the presence of an advancement catalyst at a suitable tempera- ture for a time effective for producing a solid elastomer- modified epoxy resin having an epoxy equivalent weight in the range from 500 to 1500, and recovering the solid elastomer-modified epoxy resin.

The core-shell composition of the invention can also be used as an impact modifier for vinylized epoxy resins, such as vinyl ester resins, which comprise polymerizable ethylenic unsaturation and an in situ polymerized polymer, such as a polyalkyl acrylate. A stable dispersion of an in situ polymerized polymer in a vinylized epoxy resin continuous phase can be made by providing an adduct by reacting a minor amount of func¬ tional monomer with a polyepoxide continuous phase, providing a dispersion stabilizer by reacting the adduct with at least one monomer, and polymerizing the monomer(s) in the polyepoxide continuous phase and in the presence of the dispersion stabilizer; or by providing an adduct by reacting a minor amount of functional monomer with a polyepoxide continuous phase, providing, a dispersion stabilizer by reacting the adduct with at least one monomer, while simultaneously polymerizing the monomer(s) in the polyepoxide continuous phase in the presence of the dispersion stabilizer, and vinylizing the polyepoxide. Vinlyized epoxy resins and their method of preparation are well known and disclosed in, for example, U.S. Patent No. 4,690,988 to Hoffman et al, the contents of which are hereby incorporated by reference hereon. Another class of thermosetting polymers which can be used in association with the core-shell-shell impact modifiers of the invention include thermoset polycycloolefins obtained by polymerization of a cyclo- olefin containing at least one norbornene group in the presence of a metathesis catalyst system and an effective amount of a polyfunctional cycloolefin crosslinker con¬ taining at least one norbornene group, but preferably two or more, with two or more unsaturated sites. Such ther o- set polycycloolefins are disclosed in U.S. Patent No. 4,701,510, the contents of which are hereby incorporated by reference herein.

The core-shell-shell composition of the inven¬ tion can also be used as a toughener for bismaleimide or other imide resins obtained by reaction of a bisimide having the formula:

B V N-A-N V B

in which B is a bivalent radical containing a carbon- carbon double bond and A is a bivalent radical having at least two carbon atoms with a diamino compound of the general formula H2N-E-NH2. E represents a divalent organic radical of at least two carbonates. Alternatively, the bisimide may be reacted with a polyisocyanate of the general formula D(NC0)χ in which x has a value in the range 2 to 4 and D is an x-valent organic residue. The copolymerization of bisimide with diamino compounds or polyisocyanates can be effected by simply heating a mixture of the two to a temperature between 100°C and 350°C, long enough to finalize the reaction. Examples of bismalemide resins and methods for preparing the same are disclosed in U.S. Patent No. 4,587,281 and International Application No. PCT/GB83/100350, the contents of which are hereby incorpo¬ rated by reference herein.

Still another class of thermoset polymers which can be toughened by the tougheners of the present inven- tion include block copolymers of various vinyl substituted aromatics with conjugated dienes of the S-B or S-B-S type wherein S is a vinyl substituted aromatic compound having from 8 to 12 carbon atoms such as styrene, alpha-methyl styrene, and the like, and B is a conjugated diene having from 4 to 8 carbon atoms such as butadiene, isoprene, hexadiene, and the like. Such block copolymers as well as derivatives thereof are commercially available from the

Shell Chemical Co. under the trademark Kraton. Such block copolymers can be partially hydrogenated. Moreover, blends of such block copolymers can be utilized in the above-described epoxy resins.

Cyanate ester resins such as those disclosed in

U.S. Patent Nos. 3,553,244, 3,740,348, 3,755,402,

3,448,079, 4,094,852, 4,528,366, 4,528,366, 4,748,272, and 4,894,414 can also be toughened with the composition of the invention.

The composition of the invention can also be utilized to toughen thermoplastic materials such as polyvinylhalide polymers, the preparation of which is well known in the art. Examples of patents describing polyvi- nyl halides and their preparation include U.S. Patent Nos. 4,751,118, 4,748,218 and 4,728,677. Chlorinated polyvinyl chloride homopolymers and copolymers can also be utilized with the invention. Examples of chlorinated polyvinyl chloride resin compositions are disclosed in U.S. Patent No. 5,086,122, the contents of which we hereby incorporat¬ ed by reference herein.

Other thermoplastic polymers known to the art and to the literature which can be toughened with the composition of the invention include aromatic and aliphat¬ ic polycarbonates, polyesters such as poly(ethylkene tere- phthalate) and poly(butylene terephthalate) , polyamides such as nylon 6,6, nylon 6, etc., polystyrene, poly(alkylene dicarboxylates) polyolefins such as poly¬ propylene, and the like.

Polyphenylene ethers such as disclosed in U.S. Patent No. 4,866,130, hereby incorporated by reference herein, can also be advantageously modified with the invention.

In addition to the above examples, various copolymers and blends thereof are possible and can be used in connection with the invention. Various conventional adjutants, pigments, and fillers can also be dispersed in the matrix along with the core-shell-shell composition of the invention.

The resulting blend, having improved impact resistance, can be processed by casting or compression molding. Extrusion or injection molding may be used for various formulations. Suitable uses of the compositions of the present invention includes toolings, adhesive joints, fiber reinforced composites for components used in airplanes, construction, sportswear, electrical applica¬ tions, household and consumer articles, automotive appli¬ cations such as light coverings, radiator grills, photo¬ graphic and optical equipment such as camera and binocular housings, construction such as industrial and greenhouse windows, and the like.

The invention will be better understood by reference to the following examples.

Example 1

A five-liter jacketed flask with five-necks was equipped with a reflux condenser, a pneumatic stirrer, and a thermocouple connected to a temperature recorder. The monomer emulsions for each layer of the composition were kept in separate reservoirs and metered or delivered to the jacketed flask at a controlled rate via nylon tubing and a metering pump connecting each reservoir to one of the necks of the jacketed flask. The reactor vessel was thoroughly purged with nitrogen and maintained under a constant flow of nitrogen gas throughout the emulsion polymerization. All monomer emulsions were prepared and maintained separately under a nitrogen atmosphere. The reactor was charged with Reactor Solution and heated to 75°C. Freshly prepared Initiator Solution was then added to the reactor. Immediately after the addition of the Initiator Solution to the reactor, Monomer Emulsion I was metered into the reactor at a predetermined rate with stirring. After polymerization of the first phase, or core, the emulsion formed was continu¬ ously stirred while maintaining the temperature. Total solids were measured to find the degree of polymerization of the first phase. Immediately after the conversion of more than

95% of the first phase polymerization was completed, monomer Emulsion II was metered into the reactor at a predetermined rate. After the complete polymerization of the second phase, or inner shell (determined by total solids measurements) , monomer Emulsion III was then metered into the reactor at a predetermined rate. Whenev¬ er the reaction stopped or slowed down throughout the polymerization, a batch of freshly prepared Booster Solution was added to the reactor. The polymer emulsion was cooled to about 40°C with continued stirring. Redox Tail Solution A was added to the emulsion and stirred for an hour or two, then Redox Tail Solution B was added and stirred for an additional hour. The heat was turned off and the polymer emulsion was cooled. The cooled polymer emulsion was dropped through the bottom of the reactor into a container.

The emulsion was spray dried using an electri¬ cally heated, wheel atomizing spray dryer, and then collected using a cyclone, to produce free flowing pow- ders.

Another method used to produce free flowing powders was freeze coagulation, wherein the emulsion was maintained at a temperature of about 0°C overnight to cause coagulation. The coagulum was filtered and repeat¬ edly washed with fresh water and vacuum dried. This method may reduce emulsifier level due to the repeated washing whereas the spray dried emulsions normally con¬ tains emulsifier at the level added during polymerization. Using a grinding mill, the dried coagulum was pulverized to the desired sizes.

EXAMPLES 2. 3, 4 AND 5 Four additional examples of multilayer core- shell composition in accordance to the invention were prepared. These examples were prepared in a manner essentially identical to that described by Example 1 except that the composition of Monomer Emulsion III was modified to form outer-shells having the compositions shown in Table I.

Table 1 summarizes, for each of the above exam- pies, the latex composition, the pH and total solids of the latex, and the yield and particle sizes of the spray dried product.

TABLE 1

SPRAY DRY σ.

NOTE: 12-Ethylhexyl Acrylate, 2 Methyl MethacryJLate, 3 EA = Ethyl Acrylate, 4 AN = Acrylonitrile,

'' AAAA == AAccrryylliicc AAcciidd,, "" IIAA IIttaaccoonniicc AAcciid, ' GMA = Glycidyl Methacrylate, ° CL = Polycaprolactone-diol Acrylate

Table 2 indicates that free flowing powders of different particle sizes can be produced according to the procedure described in Example 1 by using different drying methods. The toughener A was freeze coagulated, dried, and pulverized. The Tougheners B and C were spray dried using different orifice sizes to generate two different particle sizes.

TABLE 2. Particle Sizes of Tougheners

MECHANICAL TESTING: ADHESIVE JOINTS Adhesive formulations were mixed by hand, then cured. They were then tested on cold rolled steel (CRS) and electro-galvanized steel (EGS) using ASTM procedures D-1002 and D-1876 for lap-shear and T-peel resistance, respectively. The metal coupons were 1 x 4 x 0.030 inch. A 1/2" overlap was used for lap-shear tests and a 3" bond was used for the T-peel tests. The bond thicknesses were 0.019 inch. Adhesion tests were made at room temperature. Tables 3, 4, and 5 summarize the results for lap-shear and T-peel strength tests on adhesive formulations using tougheners A, B, and C. The adhesive formulations com¬ prise a liquid diglycidyl ether of bisphenol A (DGEBA) , having an epoxy equivalent weight of about 390, which is sold by Shell Chemical Co. under the trademark "Epon ® 828"; a sintered alumina sold by Alcoa Chemical Divison as "Tabular Alumina T-64"; amorphous hydrophobic silicon dioxide available from Cabot Corporation and sold under the trademark "Cab-O-Sil ®"; dicyandiamide; and a cure accelerator available from Omicron Chemicals Inc. and sold under the trademark "Omnicure ® 94". The tables show the effects of varying the amount of toughener in the formula¬ tion.

TABLE 3. Adhesive Formulations & Adhesive Strengths

Toughener A is effective at increasing the lap- shear strength and T-peel strength for all amounts of toughener added and generally shows improvement in these strengths as the amount of toughener is increased.

Table 4 indicates that Toughener B has improved T-peel strength on oily electrogalvanized steel substrate.

The other three adhesion measurements showed marginally improved toughening effects with the addition of Toughener

B.

Table 5 indicates that the Toughener C, with the smallest particle sizes, showed marginally improved adhesion strength.

The Toughener A with the largest particles, (as shown in Table 2) , showed the best toughening efficiency (as seen by comparison of Tables 3, 4, and 5). For other adhesive joints, with different type of substrates, adhesive bond thicknesses, adhesive formu¬ lations, cure procedures, etc., the tougheners with different particle sizes may give better toughness as described typically by Bascom et al, Advances in Chemistry Series, vol. 222, C. K. Riew, Ed., American Chemical Society, Washington D.C., and by other authors.

Lap-shear tests were performed on epoxy resin blends containing various amounts of the toughener materi- al from Example 1 which were freeze coagulated, dried and pulverized to an average particle size of 18 micrometers (Toughener A) , and compared to the lap-shear results for the same epoxy resin blend without any toughener and to the lap shear results for the same epoxy resin blend with reference tougheners (Tougheners D and E of Table 7) . The lap-shear results are shown in Table 6. A total of eight specimens for each sample were tested. The amount of toughener is given in parts by weight per hundred parts by weight of resin. Toughener (A) is that of the present invention.

The conventional approach to produce the impact modifiers or tougheners is to produce the highest possible rubber content in a multilayer polymers such as Toughener (D) and (E) . The Toughener (D) has a high rubbery core (60%) with a plastic inner shell, a terpolymer of methylmethacrylate (MMA)-ethylacrylate (EA) and a plastic outer-shell which is a copolymer of styrene (ST)-acrylic acid (AA) with the reactive carboxylic groups. Toughener (E) has again a high rubbery 2-EHA core (50%) and a plastic shell com- prised of MMA and EA. The compositions of the tougheners are summarized in Table 7. The epoxy resin blend used for the lap-shear tests consisted of 60 phr of tetraglycidyl ether of methylene diphenyldiamine, 40 phr of a blend of diglycidyl ether of bisphenol A, and 42 phr of diphenyl- dianaline sulfone curing agent. The lap-shear results indicate that the toughen¬ er of the present invention (Toughener A) in spite of its low elastomer content, consistently performs significantly better than the higher rubber containing Tougheners D and E.

TABLE 6

Toughener None E

Amount, phr 2.5 2.5 2.5 5.0 5.0 5.0 10 10 10 15 15 15

Lap-Shear, kg cm2* 31 55 49 42 54 45 47 61 40 45 55 48 45

TABLE 7

ω ^

MECHANICAL TESTING: TOUGHNESS PROPERTIES FOR BULK (NEAT) AND EPOXY-GRAPHITE COMPOSITES.

According to the procedure described by Hoising- ton et al in Polymeric Materials : Science and Engineering, 63, 797-801, (1990), an epoxy-graphite composite was made. The processing was accomplished using two impregnation steps followed by an autoclave curing process to consoli¬ date the final laminate. The final multilayer laminate structure contained layers of matrix resin with reinforc- ing carbon fibers separated by thin layers of matrix resin with particulate Toughener-A. The interlaminar fracture toughness of an epoxy-graphite composite was measured in Mode II fracture. The Mode II fracture toughness, GJJC, was increased from 500 J/irr for unmodified epoxy resin to 890 J/m2 for the toughened epoxy resin.

The data in Table 8 indicates that the toughness properties expressed by Klc or GIc, are improved, without a significant sacrifice of the load bearing properties, such as tensile modulus and strength.

Table 8. Mechanical Properties

HEAT STABILITY TESTING

Thermo-gravimetric analyses under air on the spray dried powders from Samples 1, 2 and 5 (Table 1) were performed. The results were compared with those of two commercial tougheners available from the Rohm & Haas Company. The results are shown in Tables 9 and 10. Rohm & Haas' KM-334 is believed to have a saturated highly crosslinked n-butylacrylate core and a methyl methacrylate shell, and KM-680 is believed to have a highly crosslinked butadiene core with a methyl methacrylate-styrene shell.

The results show that the tougheners of the invention have better thermal stability than commercially available tougheners and might therefore be used advanta¬ geously for high temperature applications.

TABLE 9

WEIGHT LOSS, % Isothermal Testing at 250°C for 5 hours under air.

Time (Minutes) Sample 1 Sample 2 Sample 5 KM-680 KM-334

30 60 90 120 150 180 210 240 270 300 ω

TABLE 10 oo Weight Loss vs. Temperature at 2°C per minutes heating rates under air.

TEMPERATURE (Degrees C )

Weight Loss % Sample 1 Sample 2 Sample 5 KM-680 KM-334

5 281 235 233 10 291 292 15 297 308 245 20 302 318 252 30 311 332 269 40 318 341 292 50 324 347 312

While in accordance with the Patent Statutes, the best mode and preferred embodiment has been set forth, the scope of the invention is not limited thereto, but rather by the scope of the attached claims.

Claims

WHAT IS CLAIMED IS:
1. A multilayer core-shell polymer composition comprising; a rigid plastic core having a Tg of at least
20°C; an elastomeric inner shell, the elastomers having a Tg less than 10°C and a molecular weight of at least about 5000; a rigid plastic outer shell having a Tg of at least 20°C; said composition being free of grafting and crosslinking agents.
2. A composition as set forth in claim 1, wherein the plastic core and outer shell are formed from one or more monomers of alkyl (meth)acrylates, wherein the alkyl portion has from about 1 to about 3 carbon atoms; vinyl substituted aromatics having from about 8 to about 12 carbon atoms; vinyl nitrile compounds or derivatives thereof having up to about 12 carbon atoms; or mono- olefins having from 2 to 6 carbon atoms.
3. The composition of claim 2, wherein said monomers are methyl (meth)acrylate, ethyl (meth)acrylate, t-butyl (meth)acrylate, propyl (meth)acrylate, styrene, styrene with α-methyl or ring substituted -chloro groups, acrylonitrile or methacrylonitrile.
4. The composition of claim 2, wherein said plastic core and said plastic outer shell are formed of copolymers or terpolymers of styrene-acrylonitrile, styrene-methyl (meth)acrylate-acrylonitrile, methyl (meth)acrylate-acrylonitrile, styrene-methyl - (meth)acrylate or styrene-maleic anhydride.
5. A composition as set forth in claim 2, wherein the outer shell further comprises a comonomer with at least one reactive functional group to improve adhesion at the interface between said composition and a matrix resin toughened by said composition, said comonomer comprising less than 50 percent of the total weight of the outer plastic shell.
6. A composition as set forth in claim 5, wherein the comonomer is a mono- or di-functional organic acid, an anhydride of a diacid, an hydroxyl-containing compound, an amine, or a compound containing one or more epoxy groups.
7. The composition of claim 5, wherein said elastomeric inner shell is formed from at least one type of elastomer-forming monomer having the formula
A 0
CH2=C—C—OB wherein A is a hydrogen or an alkyl having from 1 to 3 carbon atoms and B is an alkyl having from 4 to 20 carbon atoms, and wherein said comonomer with at least one reac¬ tive functional group is itaconic acid, itaconic anhy¬ dride, maleic acid, maleic anhydride, fumaric acid, allyl acetic acid, (meth)acrylic acid, hydroxy ethyl (meth)- acrylate, hydroxyl-ethoxyethyl (meth)acrylate, hydroxyl- ethoxyethyl acrylate, or glycidyl (meth)acrylate.
8. The composition of claim 7, wherein said elastomer-forming monomer is ethyl (meth)acrylate, butyl
(meth)acrylate, pentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, stearyl (meth)- acrylate, or lauryl (meth)acrylate.
9. The composition of claim 8, wherein a plastic forming comonomer comprising up to 25 percent by weight of the inner shell is utilized, and wherein said plastic forming comonomer is styrene or acrylonitrile.
10. The composition of claim 8, wherein said elastomeric inner shell is made from an elastomer which has a saturated backbone to improve oxidative and ultravi¬ olet radiation stabilities.
11. The composition of claim 1, wherein said elastomeric inner shell comprises from about 5 percent to about 80 percent of the total weight of said composition, said outer shell comprises from about 5 percent to about 30 percent of the total weight of said composition, and said core comprises from about 10 percent to about 90 percent of the total weight of said composition.
12. A composition as set forth in claim 11, wherein said composition is provided in the form of free flowing particles having a diameter in the range from about 5 nanometers to about 150 micrometers.
13. A composition as set forth in claim 12, wherein the ratio of the elastomeric inner-shell layer's thickness to the total diameter of the core and the inner shell is in the range from about 1:200 to about 1:2.
14. A composition as set forth in claim 1, wherein the plastic core and outer shell is formed from one or more monomers of an alkyl (meth)acrylate, wherein the alkyl portion has from about 1 to about 3 carbon atoms; a vinyl substituted aromatic having from about 8 to about 12 carbon atoms; a vinyl nitrile compound or deriva- tive thereof having up to about 12 carbon atoms; or mono- olefins having from 2 to 6 carbon atoms; and wherein the outer shell further comprises comonomers used to improve the compatibility of the outer-shell with the matrix by increasing the attractive intermolecular interactions between the outer-shell and the matrix.
15. A composition as set forth in claim 14, wherein the matrix is a thermoplastic and the comonomer used to improve the compatibility of the outer-shell with the matrix is styrene.
16. A composition as set forth in claim 14, wherein the matrix is formed from an epoxy resin and the comonomer used to improve the compatibility of the outer shell with the matrix is an alkyl (meth)acrylate, (meth)- acrylonitrile, or a monomer containing radicals of poly¬ ether, polyester, polyamide, polyimide, polyarylethers, or polyarylesters.
17. A multilayer core-shell polymer composition for toughening a matrix resin, comprising: a rigid plastic polymer core having a Tg of at least 20°C, the core being formed from one or more plastic forming monomers of alkyl (meth)acrylates, wherein the alkyl portion has from about 1 to about 3 carbon atoms; vinyl substituted aromatics having from about 8 to about 12 carbon atoms; or vinyl nitrile compounds and deriva¬ tives thereof having up to about 12 carbon atoms; or mono- olefins having from 2 to 6 carbon atoms; an elastomeric polymer inner shell, the elasto- mers having a Tg less than 10°C and a molecular weight of at least about 5000, the elastomeric inner shell being formed from at least one type of elastomer forming monomer having the formula A O
CH2=C—C- -OB wherein A is a hydrogen or an alkyl having from 1 to 3 carbon atoms and B is an alkyl having from 4 to 20 carbon atoms; a rigid plastic polymer outer shell having a Tg of at least 20°C, the outer shell being formed from one or more plastic forming monomers of alkyl (meth)acrylates, wherein the alkyl portion has from about 1 to about 3 carbon atoms; vinyl substituted aromatic having from about 8 to about 12 carbon atoms; or vinyl nitrile compounds and derivatives thereof having up to about 12 carbon atoms; or mono-olefins having from 2 to 6 carbon atoms. said composition being free of grafting and crosslinking agents.
18. A composition as set forth in claim 17, wherein the outer shell further comprises a comonomer with at least one reactive functional group to improve adhesion at the interface between said composition and a matrix resin toughened by said composition, and wherein said comonomer with at least one reactive functional group comprises less than 50 percent of the total weight of the outer plastic shell.
19. A composition as set forth in claim 18, wherein the comonomer with at least one reactive function¬ al group is a mono- or di-functional organic acid, an anhydride of a diacid, an hydroxyl-containing compound, an amine, or a compound containing one or more epoxy groups.
20. The composition of claim 18, wherein said plastic forming monomers are methyl (meth)acrylate, ethyl (meth)acrylate, t-butyl (meth)acrylate, propyl (meth)- acrylate, styrene, styrene with α-methyl or ring substi¬ tuted chloro groups, acrylonitrile or (meth)acrylonitrile, and wherein said comonomer with at least one reac¬ tive functional group is itaconic acid, itaconic anhy- dride, maleic acid, maleic anhydride, fumaric acid, allyl acetic acid, (meth)acrylic acid, hydroxy ethyl (meth)- acrylate, hydroxyl-ethoxyethyl (meth)acrylate, hydroxyl- ethoxyethyl acrylate, or glycidyl (meth)acrylate.
21. The composition of claim 17, wherein said plastic core and said plastic outer shell are formed of copolymers or terpoly ers of styrene-acrylonitrile, styrene-methyl (meth)acrylate-acrylonitrile, methyl ( eth)acrylate-acrylonitrile, styrene-methyl (meth)- acrylate or styrene-maleic anhydride.
22. The composition of claim 17, wherein said elastomer forming monomer is ethyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, stearyl (meth)- acrylate, or lauryl (meth)acrylate.
23. The composition of claim 22, wherein a plastic forming comonomer is utilized in the inner shell and comprises up to 25 percent by weight of the inner shell, and wherein said plastic forming comonomer is styrene or acrylonitrile.
24. The composition of claim 22, wherein said elastomeric inner shell polymer has a saturated backbone to improve oxidative and ultraviolet radiation stabili¬ ties.
25. The composition of claim 17, wherein said elastomeric inner shell comprises from about 5 percent to about 80 percent of the total weight of said composition, and wherein said outer shell comprises about 5 percent to about 30 percent of the total weight of said composition, and said core comprises from about 10 percent to about 90 percent of the total weight of said composition; said composition being in the form of free flowing particles having a diameter in the range from about 5 nanometers to about 150 micrometers; and wherein the ratio of the elastomeric inner-shell layer's thickness to the total diameter of the core and the inner shell is in the range from about 1:200 to about 1:2.
26. A composition as set forth in claim 17, and wherein the outer shell further comprises comonomers used to improve the compatibility of the outer-shell with the matrix by increasing the attractive intermolecular interactions between the outer-shell and the matrix.
27. A composition as set forth in claim 26, wherein the matrix is a thermoplastic and the comonomer used to improve the compatibility of the outer-shell with the matrix is styrene.
28. A composition as set forth in claim 26, wherein the matrix is formed from an epoxy resin and the comonomer used to improve the compatibility of the outer- shell with the matrix is styrene, (meth)acrylonitrile, or a monomer containing radicals of polyether, polyester, polyamide, polyimide, polyarylethers, polyarylesters or styrene maleic anhydride.
29. A polymer composition having improved impact resistance, comprising: a thermosetting or thermoplastic matrix; and from about 1 to about 40 parts by weight of a multiple layer core shell polymer composition per 100 parts by weight of said polymer matrix material; wherein said core shell polymer composition comprises: a) a rigid plastic core having a Tg of at least 20°C, the core being formed from one or more monomers of alkyl (meth)acrylates, wherein the alkyl portion has from about 1 to about 3 carbon atoms; vinyl substituted aromat¬ ic having from about 8 to about 12 carbon atoms; or vinyl nitrile compounds and derivatives thereof having up to about 12 carbon atoms; or mono-olefins having from 2 to 6 carbon atoms; b) an elastomeric inner shell, the elastomers having a Tg less than 10°C and a molecular weight of at least about 5000, the elastomeric inner shell being formed from at least one type of monomer having the formula
A O
CH2=C C OB wherein A is a hydrogen or an alkyl having from 1 to 3 carbon atoms and B is an alkyl having from 4 to 20 carbon atoms; c) a rigid plastic outer shell having a Tg of at least 20°C, the outer shell being formed from one or more monomers of alkyl (meth)acrylates, wherein the alkyl portion has from about 1 to about 3 carbon atoms; vinyl substituted aromatics having from about 8 to about 12 carbon atoms; or vinyl nitrile compounds and derivatives thereof having up to about 12 carbon atoms; or mono- olefins having from 2 to 6 carbon atoms; said composition being free of grafting and crosslinking agents.
30. A polymer composition according to Claim 29, wherein said matrix is an epoxy, vinylized epoxy, polycycloolefin, bismaleimide, polycarbonate, polyester, polyamide, polystyrene, polyphenylene ether or polyolefin resin.
31. A method of improving the toughness and impact resistance of a polymeric material comprising the steps of:
(1) blending with said polymeric material a multiple layer core-shell polymer composition having: a) a rigid plastic core having a Tg of at least 20°C, the core being formed from one or more monomers of alkyl (meth)acrylates, wherein the alkyl portion has from about 1 to about 3 carbon atoms; vinyl substituted aromat- ics having from about 8 to about 12 carbon atoms; or vinyl nitrile compounds and derivatives thereof having up to about 12 carbon atoms; or mono-olefins having from 2 to 6 carbon atoms; b) an elastomeric inner shell, the elastomers having a Tg less than 10°C and a molecular weight of at least about 5000, the elastomeric inner shell being formed from at least one type of monomer having the formula
A O
I II
CH2=C—C—OB wherein A is a hydrogen or an alkyl having from 1 to 3 carbon atoms and B is an alkyl having from 4 to 20 carbon atoms; c) a rigid plastic outer shell having a Tg of at least 20°C, the outer shell being formed from one or more monomers of alkyl (meth)acrylates, wherein the alkyl portion has from about 1 to about 3 carbon atoms; vinyl substituted aromatics having from about 8 to about 12 carbon atoms; or vinyl nitrile compounds and derivatives thereof having up to about 12 carbon atoms; or mono- olefins having from 2 to 6 carbon atoms; said composition being free of ' grafting and crosslinking agents; and
(2) forming an article from said blend.
PCT/US1993/002993 1992-04-15 1993-03-30 Multilayer core-shell polymer compositions as toughener for thermosets and thermoplastics WO1993021274A1 (en)

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4313087A1 (en) * 1993-04-22 1994-10-27 Basf Ag A particulate graft polymer and obtained therefrom thermoplastic molding composition
EP0659833A1 (en) * 1993-12-21 1995-06-28 Ciba-Geigy Ag Compositions based on epoxy resins, impact modifiers and amines
US6130290A (en) * 1998-04-29 2000-10-10 Rohm And Haas Company Impact modifier for amorphous aromatic polyester
US6316527B1 (en) 1999-09-16 2001-11-13 Rohm And Haas Company Modified SAN resin blend compositions and articles produced therefrom
US6526213B1 (en) 1998-05-22 2003-02-25 Fiberstars Incorporated Light pipe composition
US8017689B2 (en) * 2008-08-08 2011-09-13 The Yokohama Rubber Co., Ltd. Composition of epoxy resin, core-shell particles and curing agent

Citations (5)

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Publication number Priority date Publication date Assignee Title
FR2101815A5 (en) * 1970-07-17 1972-03-31 Rohm & Haas
US4173600A (en) * 1976-06-25 1979-11-06 Mitsubishi Rayon Co., Limited Multi-stage sequentially produced polymer composition
EP0050848A2 (en) * 1980-10-23 1982-05-05 Kureha Kagaku Kogyo Kabushiki Kaisha Vinyl chloride resin composition
EP0204974A2 (en) * 1985-05-10 1986-12-17 Mitsubishi Rayon Co., Ltd. Lubricant for thermoplastic resins and thermoplastic resin composition comprising said lubricant
EP0522351A1 (en) * 1991-06-29 1993-01-13 Röhm Gmbh Impact modifier

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2101815A5 (en) * 1970-07-17 1972-03-31 Rohm & Haas
US4173600A (en) * 1976-06-25 1979-11-06 Mitsubishi Rayon Co., Limited Multi-stage sequentially produced polymer composition
EP0050848A2 (en) * 1980-10-23 1982-05-05 Kureha Kagaku Kogyo Kabushiki Kaisha Vinyl chloride resin composition
EP0204974A2 (en) * 1985-05-10 1986-12-17 Mitsubishi Rayon Co., Ltd. Lubricant for thermoplastic resins and thermoplastic resin composition comprising said lubricant
EP0522351A1 (en) * 1991-06-29 1993-01-13 Röhm Gmbh Impact modifier

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4313087A1 (en) * 1993-04-22 1994-10-27 Basf Ag A particulate graft polymer and obtained therefrom thermoplastic molding composition
EP0659833A1 (en) * 1993-12-21 1995-06-28 Ciba-Geigy Ag Compositions based on epoxy resins, impact modifiers and amines
US6130290A (en) * 1998-04-29 2000-10-10 Rohm And Haas Company Impact modifier for amorphous aromatic polyester
US6526213B1 (en) 1998-05-22 2003-02-25 Fiberstars Incorporated Light pipe composition
US6316527B1 (en) 1999-09-16 2001-11-13 Rohm And Haas Company Modified SAN resin blend compositions and articles produced therefrom
US8017689B2 (en) * 2008-08-08 2011-09-13 The Yokohama Rubber Co., Ltd. Composition of epoxy resin, core-shell particles and curing agent

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