| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | October 23, 2001 |
| PATENT TITLE |
Thermoplastic resin composition having impact resistance |
| PATENT ABSTRACT |
A thermoplastic resin composition comprises a thermoplastic resin (A) and graft copolymer particles (B) having a hollow rubber portion and graft chain, in which a volumetric proportion of hollow part in the hollow rubber portion of the graft copolymer particles is 1 to 70% by volume. The thermoplastic resin composition contains the thermoplastic resin and the graft copolymer particles in a weight ratio (A)/(B) of 2/98 to 100/1. The hollow part in the graft copolymer particle functions to further improve impact resistance. |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | October 22, 1999 |
| PATENT FOREIGN APPLICATION PRIORITY DATA | This data is not available for free |
| PATENT PARENT CASE TEXT | This data is not available for free |
| PATENT CLAIMS |
What is claimed is: 1. A thermoplastic resin composition which has improved impact resistance, comprises a thermoplastic resin (A) and graft copolymer particles (B) having a hollow rubber portion and graft chain and contains the thermoplastic resin (A) and the graft copolymer, particles in a weight ratio (A)/(B) of 2/98 to 100/1. 2. The composition of claim 1, wherein the graft copolymer particles (B) comprise a particle composed of 10 to 95% by weight of the hollow rubber portion and 5 to 90% by weight of the graft chain obtained by polymerizing a vinyl monomer graft-copolymerizable with said rubber portion. 3. The composition of claim 1, wherein a volumetric proportion of hollow part in the hollow rubber portion of the graft copolymer particle (B) is 1 to 70% by volume on the basis of the hollow rubber portion. 4. The composition of claim 2, wherein a volumetric proportion of hollow part in the hollow rubber portion of the graft copolymer particle (B) is 1 to 70% by volume on the basis of the hollow rubber portion. 5. The composition of claim 1, wherein an average particle size of the graft copolymer particles is from 50 to 2,000 nm. 6. The composition of claim 2, wherein an average particle size of the graft copolymer particles is from 50 to 2,000 nm. 7. The composition of claim 3, wherein an average particle size of the graft copolymer particles is from 50 to 2,000 nm. 8. The composition of claim 4, wherein an average particle size of the graft copolymer particles is from 50 to 2,000 nm. 9. The composition of claim 1, wherein the rubber of the hollow rubber portion is a diene rubber, acrylic rubber, silicone rubber or olefin rubber. 10. The composition of claim 1, wherein the rubber of the hollow rubber portion is a rubber composition comprising 100 parts of a crosslinked copolymer obtained by polymerization of 0.05 to 40% by weight of a crosslinkable monomer and 99.95 to 60% by weight of a monomer copolymerizable with said crosslinkable monomer and 0.05 to 50 parts by weight of a polymer being different from said crosslinked copolymer. 11. The composition of claim 2, wherein the vinyl monomer comprises 60 to 100% by weight of at least one monomer selected from the group consisting of an aromatic vinyl compound, vinyl cyanide compound, vinyl chloride and (meth)acrylate compound and 0 to 40% by weight of other monomer copolymerizable with said monomer. 12. The composition of claim 1, wherein the thermoplastic resin (A) is at least one selected from the group consisting of vinyl chloride resin, aromatic vinyl resin, acrylic resin, carbonate resin, polyester resin, amide resin and an olefin resin. 13. The composition of claim 12, wherein the vinyl chloride resin contains not less than 50% by weight of vinyl chloride unit. 14. The composition of claim 12, wherein the aromatic vinyl resin contains not less than 50% by weight of aromatic vinyl unit. 15. The composition of claim 1, wherein the thermoplastic resin (A) is a polymer alloy containing at least one of vinyl chloride resin, acrylic resin, aromatic vinyl resin, carbonate resin, polyester resin, amide resin and olefin resin. 16. The composition of claim 15, wherein the thermoplastic resin (A) is a polymer alloy of aromatic vinyl resin and vinyl chloride resin. -------------------------------------------------------------------------------- |
| PATENT DESCRIPTION |
TECHNICAL FIELD OF THE INVENTION The present invention relates to a thermoplastic resin composition having impact resistance, particularly to a thermoplastic resin composition having impact resistance and comprising a thermoplastic resin and graft copolymer particles having a hollow rubber portion. BACKGROUND ART Conventional thermoplastic resins, for example, vinyl chloride resins such as polyvinyl chloride; acrylic resins such as polymethyl methacrylate; aromatic vinyl resins such as polystyrene and styrene-acrylonitrile copolymer; carbonate resins such as polycarbonate; amide resins such as Nylon 6; polyester resins such as polyethylene terephthalate; olefin resins such as polypropylene; and polymer alloys of those resins, for example, alloy of styrene-acrylonitrile copolymer and polycarbonate, alloy of .alpha.-methylstyrene-acrylonitrile copolymer and polyvinyl chloride and alloy of polystyrene and polyphenylene oxide are inherently low in impact resistance. In order to improve impact resistance of those resins and alloys thereof, generally there have been widely employed methods for adding, to rubber particles, graft copolymer particles obtained by graft-copolymerizing various monomers. Though the degree of improvement of impact resistance by the addition of the graft copolymer particles is remarkable, for further improving the impact resistance efficiently, there have been made many proposals of improving graft copolymer particles. The methods disclosed in those proposals are a method of lowering Tg of rubber particles (JP-A-2-1763, JP-A-8-100095), a method of regulating gel content of rubber particles, a method of matching particle size and particle size distribution of rubber particles in graft copolymer particles to those of thermoplastic matrix resin (S. Wu, Polymer Engineering and Science, 30,753 (1990)), a method of adjusting compatibility of graft copolymer particles with thermoplastic matrix resin (JP-A-2-251553), etc. However improvement by those methods have reached their limits, and it is difficult to improve impact resistance more significantly. Also when an adding amount of graft copolymer particles is increased, there is a problem that other characteristics, for example, processability, weather resistance and economic efficiency are lowered. Meanwhile crazing and shearing yield are an important factor on improvement of impact resistance of a thermoplastic resin. In order to cause such phenomena, stress concentration in a molded article is inevitable. For that purpose, rubber particles are added. Optimizing a size, shape and softness (Tg and degree of crosslinking of rubber) of rubber particles also has a great effect on the stress concentration, and it is anticipated that making a large cavity in the rubber particle previously has greater influence on the stress concentration ("Impact Resistance of Plastics" by Ikuo Narisawa, pp. 131, 155, published by Siguma Shuppan (1994)). However this proposal is hypothetical, and how it is realized is not disclosed. In order to realize production of hollow graft copolymer particles, the present inventors have made various studies even with respect to different techniques which are not usually studied, and have found that when a technique for hollowing of particles which is known in the field of paints is applied, hollow graft copolymer particles can be prepared and that when such hollow graft copolymer particles are added to a thermoplastic resin, impact resistance can be further improved. Thus the present invention was completed. SUMMARY OF THE INVENTION Namely the present invention relates to the thermoplastic resin composition which has improved impact resistance, comprises a thermoplastic resin (A) and graft copolymer particles (B) having a hollow rubber portion and graft chain and contains the thermoplastic resin (A) and the graft copolymer particles (B) in a weight ratio (A) (B) of 2/98 to 100/1. It is preferable that the graft copolymer particles comprise a particle composed of 10 to 95% (% by weight, hereinafter the same) of the hollow rubber portion and 5 to 90% of the graft chain obtained by polymerizing a vinyl monomer graft-copolymerizable with the rubber portion. It is preferable that a volumetric proportion of hollow part in the hollow rubber portion of the graft copolymer particles is 1 to 70% by volume on the basis of the hollow rubber portion and further that the hollow rubber portions comprise hollow rubber particles having an average particle size of 50 to 2,000 nm. It is preferable that the rubber of the hollow rubber portion constituting the graft copolymer particle is a rubber polymer of a diene rubber, acrylic rubber, silicone rubber or olefin rubber, or a rubber composition comprising 100 parts (part by weight, hereinafter the same) of a crosslinked copolymer obtained by polymerization of 0.05 to 40% of a crosslinkable monomer, 99.95 to 60% of a monomer copolymerizable with the crosslinkable monomer and 0 to 0.5% of a hydrophilic monomer and 0.05 to 50 parts of a polymer being different from the crosslinked copolymer. Examples of the preferable starting vinyl monomer for the graft chains constituting the graft copolymer particles are a vinyl monomer comprising 60 to 100% of at least one vinyl monomer selected from the group consisting of an aromatic vinyl compound, vinyl cyanide compound, vinyl chloride and (meth)acrylate compound and 0 to 40% of other monomer copolymerizable with said monomer; or a mixture of the vinyl monomers. The preferable thermoplastic resin which is another component of the present invention is at least one selected from the group consisting of vinyl chloride resin, aromatic vinyl resin, acrylic resin, carbonate resin, polyester resin, amide resin and olefin resin. It is preferable that the vinyl chloride resin contains vinyl chloride unit in an amount of not less than 50% and that the aromatic vinyl resin contains an aromatic vinyl unit in an amount of not less than 50%. As the thermoplastic resin, there is also used preferably a polymer alloy containing at least one of vinyl chloride resin, aromatic vinyl resin, acrylic resin, carbonate resin, polyester resin, amide resin and olefin resin, particularly a polymer alloy of the aromatic vinyl resin and vinyl chloride resin. DETAILED DESCRIPTION OF THE INVENTION The thermoplastic resin composition of the present invention which has improved impact resistance basically comprises a thermoplastic resin and graft copolymer particles. The graft copolymer particle is composed of a hollow rubber portion and graft chain grafting on the hollow rubber portion. The hollow rubber portion is composed of hollow rubber particle. The hollow rubber particle can be prepared by applying technique used in the field of paints. For example, there are (a) a method of preparing a W/O/W emulsion and polymerizing a monomer of the O layer (O: hydrophobic, W: hydrophilic); (b) a method of hollowing by swelling core-shell particles having a swellable core at a temperature of not less than Tg of the shell layer; (c) a method of two stage polymerization of polymers having different solubility parameters; (d) a method of finely dispersing a polymerizable monomer mixture containing a crosslinkable monomer and hydrophilic monomer and an oily substance in water to give a O/W emulsion and then polymerizing for crosslinking and removing the oily substance after the crosslinking; and (e) a method of using a phenomenon, in which a carboxylic acid unit copolymerized in the particle moves in the particle under acidic or alkaline conditions ("Application of Synthetic Latex" by Takaaki Sugimura, et al, pp. 285, published by Kobunshi Kankokai (1993)). In the present invention, the hollow rubber particles can be prepared by any of the methods (a) to (e). From the viewpoint of not making the rubber of the hollow rubber portion hard, the methods (b) and (e) are used preferably. According to the method (d), there is no problem in that complete hollow rubber portion is synthesized. However, when a crosslinking agent is used in much amount, there is a case of causing a problem that the rubber becomes hard and impact strength is lowered. The example of the method (b) is as mentioned below. First rubber polymer particles or hard polymer particles are used as a core. To an aqueous dispersion or latex of these polymer particles are added a monomer mixture for a rubber polymer forming a shell and an oily substance for swelling the polymer particles of the core. Thus the polymer particles of the core are swelled by the oily substance. At the time when the polymer particles are swelled enough, the monomer mixture is polymerized to form the shell comprising the rubber polymer. Then by removing the oily substance swelling the core, the core is shrunk and a cavity arises between the shell of rubber polymer and the polymer particle of the core. Thus the hollow rubber particles can be obtained. As mentioned above, hollow rubber particles can be prepared by various methods. The hollow rubber particles of the present invention may be prepared by any of the methods. In the present invention, the "hollow rubber particle" which constitutes the hollow rubber portion of the graft copolymer particle may have cavity (hollow part) within the hollow rubber particle. The shape of the hollow part (cavity) is not limited, and the cavity may be in the form of sphere, flat sphere, pore or honeycomb. Also on the inner surface of the hollow part, there may exist concave or convex or protrusion. The number of the cavities is not limited to one, and many cavities may exist. The cavity may be in the form of honeycomb or salami. In the present invention, even if the hollow rubber particle is in any form, a volumetric proportion (cavity ratio) of the hollow part, in which a remarkable effect of impact resistance can be exhibited, is from 1 to 70% by volume, preferably 3 to 60% by volume, particularly 5 to 50% by volume based on the total volume of the hollow rubber portion. An average particle size of the hollow rubber particles is preferably from 50 to 2,000 nm, more preferably from 60 to 1,700 nm, particularly preferably from 70 to 1,500 nm from the viewpoint of excellent impact resistance. The particle size distribution is not limited particularly. Particles having smaller particle size may be increased, and vice versa, or remarkably narrow particle size distribution may be employed. With respect to the rubber polymer of the hollow rubber particles, a glass transition temperature (Tg) thereof is preferably not more than 0.degree. C., more preferably not more than -20.degree. C., particularly preferably not more than -30.degree. C. from the viewpoint of excellent impact resistance. Also preferable are a diene rubber, acrylic rubber, silicone rubber and olefin rubber from the points of making it possible to easily form the hollow parts, regulate a cavity ratio and exhibit impact resistance stably. Examples of the diene rubber are, for instance, a butadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, and the like. Examples of the acrylic rubber are, for instance, a butyl acrylate rubber, butadiene-butyl acrylate rubber, 2-ethylhexyl acrylate-butyl acrylate rubber, 2-ethylhexyl methacrylate-butyl acrylate rubber, stearyl acrylate-butyl acrylate rubber, dimethylsiloxane-butyl acrylate rubber, a composite rubber of a silicone rubber and butyl acrylate rubber, and the like. Examples of the silicone rubber are, for instance, a polydimethylsiloxane rubber, and the like. Examples of the olefin rubber are, for instance, an ethylene-propylene rubber, ethylene-propylene-diene rubber and the like. Among them, the diene rubber and acrylic rubber are preferable from the viewpoint of easy control of the cavity ratio and increased improvement of impact resistance and from the points that the rubbers can be formed into a latex and preparation is easy. Unrestricted examples of more preferable rubber are a styrene-butadiene rubber, butyl acrylate rubber, and the like. Further in the present invention, it is preferable that the hollow rubber particles prepared by the method (b) are used as a material for the graft copolymer particles. The technique for the preparation is explained below. First the polymer particles to be used as a core are prepared. Those polymer particles for the core may be those which are swelled by an oily substance, and play an important role in forming the hollow parts. Examples of the material for the core polymer particles are a rubber polymer, for instance, a diene rubber such as a butadiene rubber, styrene-butadiene rubber or acrylonitrile-butadiene rubber, an acrylic rubber such as a butyl acrylate rubber, butadiene-butyl acrylate rubber, 2-ethylhexyl acrylate-butyl acrylate rubber, 2-ethylhexyl methacrylate-butyl acrylate rubber, stearyl acrylate-butyl acrylate rubber, dimethylsiloxane-butyl acrylate rubber, a composite rubber of a silicone rubber and butyl acrylate rubber or butyl methacrylate rubber, a silicone rubber such as a polydimethylsiloxane rubber, an olefin rubber such as an ethylene-propylene rubber or ethylene-propylene-diene rubber; and a hard polymer such as polystyrene, styrene-acrylonitrile copolymer, styrene-methyl methacrylate copolymer; and the like. From the viewpoint of improving impact resistance, the rubber polymers are more preferable. It is preferable that these polymer particles are prepared by emulsion polymerization. The emulsion polymerization can be carried out through usual method. Subsequently the polymer particle for the core is used as a core, and a crosslinked copolymer which becomes a shell and is different from the polymer for the core in physical properties of a rubber is formed around the polymer particle. Before forming the shell of the rubber polymer, the polymer particles as the core are swelled with an oily substance to increase the volume of the particles. The oily substance may be selected properly depending on the polymer used for the core and the monomer used for forming the shell. For example, toluene, benzene or the like is used when the core is a diene rubber. Also, particularly even when the oily substance is not added, depending on the monomer used for the polymerization of the shell, the polymer particles for the core is swelled by the monomer and then the hollow particles are formed through volumetric shrinkage during the polymerization. It is preferable, from the polymerizing operations of the shell, that the oily substance is added after mixed with monomers for forming the shell which are explained hereinafter. The monomers for forming the shell are the monomers being capable of forming the rubber polymer for the above-mentioned hollow rubber particles by polymerizing. The monomers comprise preferably 0.05 to 40% of a crosslinkable monomer (1), 99.95 to 60% of a monomer (2) copolymerizable with the crosslinkable monomer (1) and 0 to 0.5% of a hydrophilic monomer (3), more preferably 0.1 to 35% of the crosslinkable monomer (1) and 99.9 to 65% of the monomer (2), particularly preferably 0.3 to 30% of the crosslinkable monomer (1) and 99.7 to 70% of the monomer (2). The monomer (2) mainly gives physical properties of the rubber. The crosslinkable monomer (1) functions to maintain a shape of the hollow rubber particles. A known crosslinking agent having two or more polymerizable functional groups in its molecule is used as the crosslinkable monomer (1). Examples thereof are, for instance, one or more of allyl methacrylate, divinylbenzene, diallyl phthalate, polyethylene glycol dimethacrylate, triallyl cyanurate, triallyl isocyanurate, triallyl trimellitate, 1,3-butylene glycol dimethacrylate, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, and the like. The monomer (2) copolymerizable with the crosslinkable monomer (1) constitutes an essential portion of the rubber polymer for the above-mentioned hollow rubber particles. Examples of the monomer (2) giving a diene rubber are, for instance, a conjugate diene monomer such as butadiene or isoprene or a monomer mixture of butadiene, styrene and acrylonitrile; and examples of the monomer (2) giving an acrylic rubber are, for instance, butyl acrylate alone or a monomer mixture of butyl acrylate with an alkyl (meth)acrylate having an alkyl group of C2 to C18 such as ethyl acrylate, ethyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, butyl methacrylate, lauryl acrylate or lauryl methacrylate or with butadiene or dimethylsiloxane; and the like. Preferable combinations of the polymer for the shell and the polymer for the core are, for example, a diene rubber as the polymer for the core and an acrylic rubber as the polymer for the shell, etc. More specifically there are a styrene-butadiene rubber as the polymer for the core and a butyl acrylate rubber as the polymer for the shell, etc. The synthesis of the crosslinked copolymer may be carried out by any polymerization method. From the viewpoint of stable control of the particle size and enhancement of impact strength, emulsion polymerization is preferable. A polymerization initiator, chain transfer agent and emulsifying agent which are used for the polymerization are not particularly limited. As the polymerization initiator, known initiators, for example, a thermal cracking initiator such as potassium persufate, a rhedox initiator such as Fe-reducing agent-organic peroxide, and the like can be used. As the chain transfer agent, known chain transfer agents, for example, t-dodecylmercaptan, n-dodecylmercaptan, .alpha.-methylstyrene dimer, terpinolene and the like can be used. As the emulsifying agent, known emulsifying agents, for example, a fatty acid metal salt emulsifying agent such as sodium oleate, sodium palmitate or sodium rhodinate, a sulfonic acid metal salt emulsifying agent such as sodium dodecylbenzenesulfonate, sodium alkylsulfonate having 12 to 20 carbon atoms or sodium dioctylsulfosuccinate, and the like can be used. Polymerization temperature and time may be selected optionally depending on monomers and initiators. From the viewpoint of economic efficiency and polymerization stability, the polymerization is carried out preferably at 30.degree. to 120.degree. C. for 2 to 50 hours. At the time of the polymerization, there also occurs crosslinking. A gel fraction of the crosslinked polymer is preferably from 5 to 100%, more preferably from 10 to 100%, particularly preferably from 20 to 100%, from the viewpoint of impact resistance. A rubber polymer having a low gel fraction or one having a high gel fraction may be mixed depending on the matrix resin and the required characteristics. After the polymerization, by removing the oily substance swelling the polymer particles of the core by evaporation, etc., the polymer particles shrink, thus causing a cavity between the core and the shell to give hollow rubber particles. According to this method, the volumetric proportion (cavity ratio) of the hollow part in the hollow rubber particle becomes 1 to 70% by volume. Mentioned above is the method for preparing the hollow rubber particles used in the present invention, which is explained according to the method (b). The hollow rubber particles usable in the present invention can be also prepared by other methods (a) to (e). On the so-prepared hollow rubber particles are provided graft chains by graft-copolymerizing a vinyl monomer. Those graft chains function to disperse the rubber particles uniformly in the thermoplastic resin. The proportion of the hollow rubber particle to the graft chain is preferably 10/90 to 95/5, more preferably 15/85 to 92/8, particularly preferably 20/80 to 92/8. By employing the proportion in the abovementioned range, an excellent effect of improving impact resistance can be obtained. Examples of the vinyl monomer constituting the graft chains are an aromatic vinyl compound, vinyl cyanide compound, (meth)acrylate compound, vinyl chloride and the like. Further a monomer copolymerizable therewith may occupy, as an optional component, at most 40% in the graft chains. Example of the aromatic vinyl compound is at least one of styrene, .alpha.-methylstyrene, p-methylstyrene, p-isopropylstyrene, chlorostyrene, bromostyrene and the like. Example of the vinyl cyanide compound is at least one of acrylonitrile, methacrylonitrile and the like. Examples of the (meth)acrylate compound are at least one of methacrylates having an alkyl group of C1 to C18 such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate and stearyl methacrylate or at least one of acrylates having an alkyl group of C1 to C18 such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate and stearyl acrylate. Examples of the other copolymerizable monomer are (meth)acrylic acid, derivatives of (meth)acrylic acid other than the above-mentioned (meth)acrylate compound, such as glycidyl (meth)acrylate; maleimide compounds such as maleimide and N-phenylmaleimide; and the like. Those monomers may be used solely or in a mixture of two or more. The graft chains can be synthesized by any graft-copolymerization methods. From the viewpoint of stability in control of a graft ratio and impact resistance, emulsion polymerization is used for the synthesis. A polymerization initiator, chain transfer agent and emulsifying agent which are used for the graft coolymerization are not particularly limited. As the polymerization initiator, known initiators, for example, a thermal cracking initiator such as potassium persufate, a rhedox initiator such as Fe-reducing agent-organic peroxide, and the like can be used. As the chain transfer agent, known chain transfer agent, for example, t-dodecylmercaptan, n-dodecylmercaptan, .alpha.-methylstyrene dimer, terpinolene and the like can be used. As the emulsifying agent, known emulsifying agents, for example, a fatty acid metal salt emulsifying agent such as sodium oleate, sodium palmitate or sodium rhodinate, a sulfonic acid metal salt emulsifying agent such as sodium dodecylbenzenesulfonate, sodium alkylsulfonate having 12 to 20 carbon atoms or sodium dioctylsulfosuccinate, and the like can be used. Polymerization temperature and time may be selected optionally depending on monomers and initiators. From the viewpoint of economic efficiency and polymerization stability, the polymerization is carried out preferably at 30.degree. to 120.degree. C. for 2 to 30 hours. The emulsion graft copolymerization can be carried out by adding a vinyl monomer, initiator, etc. to an emulsified dispersion of the above-mentioned hollow rubber particles. The method for adding the vinyl monomer is not particularly limited. The vinyl monomer may be added at one time or may be added batchwise or continuously. When an amount of the vinyl monomer is lower in comparison with the amount of the hollow rubber particles, from the viewpoint of enhancing a graft efficiency and impact resistance, it is preferable that not less than 60% of the total amount of the vinyl monomers used is added continuously. From the viewpoint of enhancing impact resistance, the graft ratio is preferably from 5 to 100%, more preferably from 8 to 80%, particularly preferably from 10 to 70%. From the viewpoint of exhibiting impact strength, the average particle size of the graft copolymer particles is preferably from 50 to 2,000 nm. By the method mentioned above, graft copolymer particles (B) having hollow rubber portions and graft chains can be obtained. The graft copolymer particles (B), when added to the thermoplastic resin (A), give excellent impact resistance to the resin composition. An adding amount of the graft copolymer particles varies depending on kind and cavity ratio thereof, kind of the thermoplastic resin, etc. It is preferable, from the viewpoint of cost and enhancement of impact resistance, that the thermoplastic resin (A) and the graft copolymer particles (B) are added in a weight ratio (A)/(B) of 2/98 to 100/1, more preferably 3/97 to 99 1, particularly 4/96 to 98/2. Example of the thermoplastic resin used in the present invention is one or more of a vinyl chloride resin, aromatic vinyl resin, acrylic resin, carbonate resin, polyester resin, amide resin and olefin resin. The impact resistance of those resins is required to be improved particularly. Examples of the vinyl chloride resin are a polyvinyl chloride, chlorinated vinyl chloride, vinyl chloride copolymer containing not less than 50% of vinyl chloride unit (copolymerizable components are vinyl acetate, ethylene, etc.), and the like. From the viewpoint of enhancement of impact resistance and processability, a weight average molecular weight thereof is preferably from 20,000 to 100,000. Examples of the acrylic resin are polymethyl methacrylate, methyl methacrylate copolymer containing not less than 50% of methyl methacrylate unit (copolymerizable components are methyl acrylate, butyl acrylate, styrene, etc.), and the like. From the viewpoint of enhancement of impact resistance and processability, a weight average molecular weight thereof is preferably from 20,000 to 200,000. Examples of the aromatic vinyl resin are polystyrene, styrene-acrylonitrile copolymer, .alpha.-methylstyrene-acrylonitrile copolymer, styrene-.alpha.-methylstyrene-acrylonitrile copolymer, styrene-maleimide copolymer, styrene-maleimide-acrylonitrile copolymer, styrene-.alpha.-methylstyrene-maleimide-acrylonitrile copolymer, styrene-maleic anhydride copolymer, and the like. From the viewpoint of enhancement of impact resistance and processability, a weight average molecular weight thereof is preferably from 10,000 to 500,000, more preferably from 20,000 to 400,000, particularly preferably from 30,000 to 300,000. Examples of the carbonate resin are bisphenol polycarbonate, aliphatic polycarbonate, and the like. From the viewpoint of impact resistance and processability, a number average molecular weight thereof is preferably from 1,000 to 100,000, more preferably from 5,000 to 80,000, particularly preferably from 10,000 to 60,000. Examples of the polyester resin are polyethylene terephthalate, polybutylene terephthalate, and the like. From the viewpoint of impact resistance and processability, a number average molecular weight thereof is preferably from 1,000 to 100,000, more preferably from 5,000 to 80,000, particularly preferably from 10,000 to 60,000. Examples of the amide resin are Nylon 6, Nylon 6,6, Nylon 12, and the like. From the viewpoint of impact resistance and processability, a number average molecular weight thereof is preferably from 1,000 to 100,000, more preferably from 5,000 to 80,000, particularly preferably from 10,000 to 60,000. Examples of the olefin resin are polypropylene, polyethylene, cyclic polyolefin, and the like. Further a polymer alloy comprising one or more of those vinyl chloride resin, acrylic resin, aromatic vinyl resin, carbonate resin, polyester resin, amide resin and olefin resin can be used as the thermoplastic resin. Examples thereof are, for instance, alloy of vinyl chloride resin-aromatic vinyl resin and in addition, alloy of styrene-acrylonitrile copolymer and polycarbonate, alloy of styrene-acrylonitrile copolymer and Nylon 6, alloy of polyethylene terephthalate and polycarbonate, alloy of polystyrene and polyphenylene oxide, and the like. Particularly an alloy of vinyl chloride resin-aromatic vinyl resin is preferable from the viewpoint of flowability. Examples of the aromatic vinyl resin used on such an alloy are polystyrene, styrene-acrylonitrile copolymer, .alpha.-methylstyrene-acrylonitrile copolymer, styrene-.alpha.-methylstyrene-acrylonitrile copolymer, styrene-maleimide copolymer, styrene-maleimide-acrylonitrile copolymer, styrene-.alpha.-methylstyrene-maleimide-acrylonitrile copolymer, styrene-maleic anhydride copolymer, and the like. From the viewpoint of enhancement of impact resistance and processability, a weight average molecular weight thereof is preferably from 10,000 to 300,000, more preferably from 15,000 to 200,000, particularly preferably from 20,000 to 150,000. Examples of the vinyl chloride resin are polyvinyl chloride, a copolymer containing not less than 80% of a vinyl chloride unit (copolymerizable components are ethylene, etc.), chlorinated polyvinyl chloride, and the like. From the viewpoint of enhancement of impact resistance and processability, the polymerization degree of the vinyl chloride resin is preferably from 300 to 2,000, more preferably from 400 to 1,500, particularly preferably from 450 to 1,300. With respect to the proportion (weight ratio) of the aromatic vinyl resin and vinyl chloride resin, from the viewpoint of enhancement of impact resistance and processability, the aromatic vinyl resin/vinyl chloride resin ratio is preferably from 5/95 to 90/10, more preferably from 10/90 to 80/20, particularly preferably from 15/85 to 75/25. For the resin composition of the present invention, well-known antioxidant, heat stabilizer, ultraviolet ray absorbent, pigment, antistatic agent, lubricant or the like can be used optionally as case demands. Particularly phenolic, sulfuric, phosphoric and hindered amine stabilizers which are used for the aromatic vinyl resin and vinyl chloride resin; stabilizers such as Sn, Pb and Ca stabilizers; ultraviolet ray absorbents such as benzophenone and benzotriazole ultraviolet ray absorbents; and internal or external lubricants such as organopolysiloxane, aliphatic hydrocarbon, ester of higher fatty acid or higher alcohol, amide or bisamide of higher fatty acid or its modified product, oligoamide and metal salt of higher fatty acid; and the like can be used for giving the composition of the present invention having higher performance as the resin for molding. Also a known flame retardant, reinforcement, filler and the like can be added. Examples of the flame retardant are a bromic organic compound such as tetrabromobisphenol A; phosphoric organic compound such as triphenyl phosphite; inorganic metal compounds of Mg(OH).sub.2, Al(OH).sub.3, Sb.sub.2 O.sub.3 and ZnO. Examples of the reinforcement and filler are a glass fiber, carbon fiber, stainless steel fiber, aluminum flake, talc, mica, calcium carbonate, whisker and the like. Those stabilizers, lubricants, flame retardants, reinforcements and fillers can be used solely or in a mixture of two or more thereof. A resin mixture of the graft copolymer particles (B) and thermoplastic resin (A) of the present invention can be prepared by mixing them in the form of a latex, slurry, solution, powder and pellets or in combination of these forms, depending on the method of preparation of (A) and (B). In case where the both of the graft copolymer particles and thermoplastic resin are in the form of a latex, a polymer powder may be obtained by a usual method, for example, by adding, to the latex, a salt of an alkaline earth metal such as calcium chloride, magnesium chloride or magnesium sulfate, a salt of an alkali metal such as sodium chloride or sodium sulfate, or an inorganic or organic acid such as hydrochloric acid, sulfuric acid, phosphoric acid or acetic acid to solidify the latex, and then dehydrating and drying the latex. Also a spray drying method can be used. A part of the stabilizer and lubricant used can be added to the latex or slurry of the above-mentioned resin in the form of a dispersion. The resin composition of the present invention can be prepared by kneading the graft copolymer particles and thermoplastic resin powder or pellets or a mixture thereof in the form of powder or pellets, and if necessary, adding a stabilizer, lubricant, flame retardant, reinforcement, pigment, etc., with a known melt-kneading machine such as Banbury mixer, roll mill, single screw extruder or double screw extruder. The resin composition of the present invention can be molded by known molding method such as extrusion molding, injection molding or vacuum molding, and can provide a molded article having more excellent impact resistance. |
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