MAKING METHOD OF IMPACT RESISTANCE RESIN COMPOSITION
Field of the Invention
The present invention relates to a method for producing an impact resistance resin composition, in particular, an impact resistance resin composition having excellent chromaticity and compatibility between impact resistance and stiffness.
Description of the Related Art
Impact resistance resins compounding rubber components such as ABS resin and high impact polystyrene have well balanced various properties and processability, and have been widely used for automobile parts, electric parts, business equipment parts and the like.
These impact resistance resins compounding rubber components need of graft polymerization of vinyl monomers such as styrene to the rubber components in order to reveal sufficient mechanical properties, and emulsion graft polymerization has been employed as the production method. However, the emulsion graft polymerization has some drawbacks; the emulsion graft polymerization includes many processes, the use of many subsidiary raw materials causes the increased cost, and draining treatment is required.
In order to decrease such drawbacks, melt blencP techniques of emulsion graft polymer, highly containing a rubber component and suspension polymer not containing a

ruBtoer component have been developed (Kobunshi Gakkai, "ABS Resin"). In recent year, the process which directly and continuously bulk-polymerizes impact•resistance resin composition containing the rubber component has been put to practical use (For example, Japanese Patent Publication No. 47-14136, Japanese Patent Publication No. 49-26711, Kagaku Kogaku 53(6), 423-426 (1989)).
Although the melt blend techniques of the emulsion graft polymer containing the rubber component with the continuous bulk polymer or the suspension polymer individually polymerized and not containing the rubber component is relatively easy to control physical properties, desirable chromaticity is not obtainable due to excessive thermal history during the melt blend and the compatibility between the impact resistance and stiffness is not satisfactory.
On the other hand, a method for producing the impact resistance resin containing the rubber component by the direct continuous bulk polymerization has advantages of reduced process and subsidiary raw materials and no draining treatment, it is difficult to contrjol the graft
i -
polymerization in the bulk polymerization, and the obtained resin does not show satisfactory chromaticity due to more excessive thermal history of the rubber component and satisfactory physical properties such as impact resistance. Furthermore, an increased rubber component causes some problems that deteriorated rubber remains and strips of-f in

,the polymerizer so that troubles arise on the production and the quality.
SUMMARY OF THE INVENTION
The inventors have reach the present invention as the results of intensive studies for the purpose of providing a method for producing impact resistance resin composition having the excellent chromaticity and compatibility between impact resistance and physical properties.
It is an object of this invention to provide an impact resistance resin composition comprising: 10 to 95 phr by weight of a copolymer (A) and 90 to 5 phr by weight of a graft copolymer (B); the copolymer (A) being in a melt state under a process continuously bulk-polymerizing a monomer mixture comprising 20 to 100 weight percent of an aromatic vinyl monomer, 0 to 60 weight percent of a vinyl cyanide monomer, 0 to 80 weight percent of a (meth)acrylic acid ester, and 0 to 60 weight percent of another copolymerizable vinyl monomer; the graft copolymer fB) being obtained by graft-polymerizing 95 to 20 phr by weight of a monomer rnixtuxe comprising 10 to 100 weight percent of an aromatic vinyl monomer, 0 to 50 weight percent of a vinyl cyanide monomer, 0 to 80 weight percent of a (meth)acrylic acid ester, and 0 to 60 weight percent of another copolymerizrable vinyl monomer in the presence of 5 to 80 phr by weight of a rubber polymer; and the graft copolymer (B) being

continuously added into the copolymer (A) in the melt state.
In the above method, it is desirable that the graft copolymer (B) is obtained by preliminarily dehydrating and drying slurry or wet cake from emulsion polymerization latex, in particular, drying the preliminarily dehydrated slurry or wet cake in air or nitrogen gas flow, or dehydrating and drying untreated slurry or wet cake by supplying to an extruder having a groove, hole or gap and a vent port make a liquid material pass through.
The feature of the present invention is producing a resin not containing rubber component by continuous bulk
polymerization, adding a graft copolymer containing the
I
rubber component at the melt state of the resin, and mixing them. The resin composition having excellent chromaticity and mechanical properties can be obtained as shown in EXAMPLE 1 to 15 by the production method of the present invention. The production method will enable to decrease draining treatment, the production process, and the production cost.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will be explained in detail below.
The aromatic vinyl monomers being a constituent of the copolymer (A) and the graft copolymer (B) used in the present invention represent aromatic compounds having a polymer!zable double bond such as, for example, styrene, a-

methylstyrene, p-methylstyrene, vinyltoluene, propylstyrene, butylstyrene, cyclohexylstyrene and the like. Among them, styrene and a-methylstyrene are preferably used.
The vinyl cyanide monomers being a constituent of the copolymer (A) and the graft copolymer (B) used in the present invention represent aromatic compounds having a polymerizable double bond and a cyano group such as, for example, acrylonitrile, methacrylonitrile, and the like. These vinyl cyanide monomers are used solely or as a mixture of more than two monomers. Among them, acrylonitrile is preferably used.
The (meth)acrylic ester monomers being a constituent of the copolymer (A) and the graft copolymer (B) used in the present invention Include, for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, glycidyl methacrylate, hydroxyethyl methacrylate, methvl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and the like. These (meth)acrylic ester monomers are used solely or as a mixture of more than two monomers. Among them, methyl methacrylate is preferably used.
The other vinyl monomers being a constituent of the copolymer (A) and the graft copolymer (B) used in the present invention include, for example, N-phenylmaleinimlde, N-cyclohexylmaleinimide, N-methyl substituted phenyl maleinimide, maleic anhydride, acrylic acid, methacrylic acid, and the like. Among them, N-phenylmaleinimide is preferably used.
The rubber polymers being a constituent of the graft

.copolymer (B) used in the present invention include, for example, diene rubbers, acrylic rubbers, ethylenic rubbers and so on, specifically, polybutadiene, poly(butadiene-styrene), poly(butadiene-acrylonitrile), polyisoprene, poly(butadiene-butyl acrylate), poly(butadiene-methyl acrylate), poly(butadiene-methyl methacrylate), poly(butadiene-ethyl acrylate), ethylene-propylene rubber, ethylene-propylene diene rubber, poly(ethylene-isobutylene), poly(ethylene-methyl acrylate), and the like. These rubber polymers are used solely or as a mixture of more than two polymers. Among them, polybutadiene, poly(butadiene-styrene), poly(butadiene-acrylonitrile), and ethylene-propylene rubber are preferably used.
Examples of suitable copolymers (A) of the present invention are polystyrene, styrene-acrylonitrile copolymer, styrene-N-phenylmaleinimide copolymer, styrene-acrylonitrile-N-phenylmaleinimide copolymer, styrene-acrylonitrile-methyl methacrylate copolymer, styrene-methyl methacrylate copolymer, and the like. Among thenji1, styrene-acrylonitrile
J:
copolymer is preferably used.
Examples of suitable graft copolymers (B) of the present invention are styrene graft copolymer of
I;
polybutadiene, styrene graft copolymer of poly(butadiene-styrene), styrene-acrylonitrile graft copolymer of polybutadiene, styrene-acrylonitrile graft copolymer of poly(butadiene-styrene), styrene-acrylonitrile graft copolymer of poly(butadiene-acrylonitrile), styrene-

atfrylonitrile-methyl methacrylate graft copolymer of polybutadiene, styrene-acrylonitrile graft copolymer of poly(ethylene-propylene), and the like.
Considering the mechanical strength of the obtained resin composition, the chromaticity and the processability, the content of each monomer in the copolymer (A) should be 20 to 100 weight percent of the aromatic vinyl monomer, 0 to 60 weight percent of the vinyl cyanide monomer, 0 to 80 weight percent of the (meth)acrylate ester monomer, and 0 to 60 weight percent of the other copolymerizable vinyl monomer, suitable content is 30 to 100 weight percent of the aromatic vinyl monomer, 0 to 50 weight percent of the vinyl cyanide monomer, 0 to 70 weight percent of the (meth)acrylate ester monomer, and 0 to 50 weight percent of the other copolymerizable vinyl monomer, and preferable content is 60 to 100 weight percent of the aromatic vinyl monomer, 10 to 40 weight percent of the vinyl cyanide monomer, 0 to 60 weight percent of (meth)acrylate ester monomer, and 0 to 40 weight percent of the other copolymerizable vinyl monomer.
Any bulk polymerization methods can be employed without restriction for the first bulk polymerization process, i.e. the continuous bulk polymerization of the monomer mixture comprising 20 to 100 weight percent of the aromatic vinyl monomer, 0 to 60 weight percent of the vinyl cyanide monomer, 0 to 80 weight percent of (meth)acrylate ester monomer, and 0 to 60 weight percent of the other copolymerizable vinyl monomer. For example, degassing after

polymerization in a polymerizer is known. The usable polymerizers include mixing types having stirring wings such as paddle wings, turbine wings, propellant wings, pull-margin wings, multistage wings, anchor wings, "Maxblend" wings, double helical wings, and the like, and various column type reactors. In addition, shell and tube reactors, kneader reactors, twin screw extruders, and similar reactors may be used as a polymerizer (Refer to, for example, Assessment of polymer production process 10 "Assessment of high impact polystyrene", Kobunshi Gakkai, January 26, 1989). These polymerizer can be used either solely or plurally, and used
in any combination of various kinds of reactors according to
• t
demand.
The reactant mixture of the copolymer (A) formed in the polymerizer or the reactor is usually served to the following monomer removing process to remove the monomers and other volatile components. Any monomer removing methods can be used as exemplified as follows; a method using an one screw or twin screw extruder with a vent port and removing volatile- components from the vent port with heating at atmospheric pressure or under reduced pressure; a method removing volatile components using an evaporator such as centrifugal type having a plate fin type heater in a drum; a method removing volatile components using a thin film evaporator such as centrifugal type; and a method removing volatile components by flushing the solution into the vacuum vessel after preheating and blowing in a shell and tube heat

exchanger. Among them, the one screw or twin screw extruder having vents is preferably used.
The continuous bulk polymerization of the copolymer (A) can be achieved by either method among thermal polymerization without an initiator, initiator polymerization with an initiator, or a combination of the thermal polymerization and the initiator polymerization. The initiators include peroxides, azo compounds and the like.
The used peroxides includes benzoyl peroxide, cumene hydroperoxide, dicumyl peroxide, diisopropylbenzene hydroperoxide, t-butyl hydroperoxide, t-butylcumyl peroxide, t-butyl peroxyacetate, t-butyl peroxybenzoate, t-butyl peroxy-isopropyl-carbonate, di-t-butyl peroxide, t-butyl peroctate, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, l,l-bis(t-butylperoxy)cyclohexane, t-butylperoxy)-2-ethyl hexanoate, and the like. Among them, cumene hydroperoxide and 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane is preferably used. The used azo compounds include azobisisobutyronitrile, azobis(2,4-dimethylvaleronitrile), 2-phenylazo-2,4-dimethylvaleronitrile), 2-phenylazo-2,4-dimethyl-4-methoxyvaleronitrile, 2-cyano-2-propylazoformamide, 1,1' -azobiscyclohexane-1-carbonitrile, azobis(4-methoxy-2,4dimethylvaleronitrile), dimethyl-2,2' -azobisisobutylate, 1-t-butylazo-1-cyanocyclohexane, 2-t-butylazo-2-cyanobutane, 2-t-butylazo-2-cyano-4-methoxy-4-methylpentane, and the like. These initiators may be used solely or in combination with more than two kinds. Among them, 1,1' -azobiscyclohexane-1-

,carbonitrile preferably can be used.
Chain transfer agents such as mercaptan compounds, terpene compounds and the like may be used in order to adjust the degree of polymerization of the copolymer (A) used in the present invention. The chain transfer agents include n-octylmercaptan, t-dodecylmercaptan, n-dodecylmercaptan, n-tetradecylmercaptan, n-octadecylmercaptan, terpinolene and the like. These chain transfer agents may be used solely or in combination with more than two kinds. Among them, n-octylmercaptan, t-dodecylmercaptan, and n-dodecylmercaptan preferably can be used.
Although the copolymer (A) used in the present Invention is produced by the continuous bulk polymerization, small amount of solvent, for example lass than 20%, may be used.
Another constituent, the graft copolymer (B), used in the present invention is a graft copolymer of 5 to 80 phr by weight of a rubber polymer with 95 to 20 phr by weight of a monomer mixture comprising 10 to 100 weight percent of an aromatic vinyl monomer, 0 to 50 weight percent of a vinyl cyanide monomer, 0 to 80 weight percent of a (meth)acrylic acid ester, and 0 to 60 weight percent of another copolymerizable vinyl monomer. The graft polymerization of all the monomer is not required, and the resulting mixture of the graft polymer and non graft polymery's usually used. Although the graft rate of the graft copolymer (B) is not limited, the rate is suitably ranging 5 to 150 weight

.percent, preferably 10 to 100 weight percent. The graft rate is calculated using the following equation: Graft rate (weight %) = (Graft portion weight / Rubber polymer weight) x 100
The content of the rubber polymer in the graft copolymer (B) should be in the range of 5 to 80 phr by weight, preferably 20 to 70 phr by weight considering the mechanical properties, chromaticity, and processability of the obtained resin composition. The content of each monomer in the graft copolymer (B) is 10 to 100 weight percent of the aromatic vinyl monomer, 0 to 50 weight percent of the vinyl cyanide monomer, 0 to 80 weight percent of the (meth)acrylic acid ester, and 0 to 60 weight percent of the other copolymerizable vinyl monomer, and preferably (1) 60 to 100 weight percent of the aromatic vinyl monomer, 10 to 4 weight, percent of the vinyl cyanide monomer, and 0 to 60 weight percent of the (meth)acrylic acid ester, or (2) 20 to 60 weight percent of the aromatic vinyl monomer, 0 to 30 weight percent of the vinyl cyanide monomer, and 40 %o 80 weight percent of the (meth)acrylic acid ester.
Although the production method of the graft copolymer (B) should not be limited, the copolymer is suitably produced by emulsion polymerization or bulk polymerization, preferably emulsion polymerization.
The emulsion polymerization represents the emulsion graft polymerization of the vinyl monomer or the vinyl monomer, mixture in the presence of the rubber polymer latex.

Any emulsifiers may be used without limitation, and various surfactants may be used. Among them, anion surfactants such as carbonic acid salt type, sulfate ester salt type, and sulfonate salt type preferably may be used. The examples of emulsifiers are caprylate salt, caprate salt, laureate salt, myristate salt, palmitate salt, stearate salt, oleinate salt, linolate salt, rhodinate salt, behenate salt, sulfate ester salt of caster oil, laurylsulfite salt, sulfate ester salts of other higher alcohols, dodecylbenzenesulfonate salt, alkylnaphthalenesulfonate salt, alkyldiphenyletherdisulfonate salt, condensation product of naphthalenesulfonate salt, dialkylsulfosuccinate salt, polyoxyethylenelaurylsulfate salt, polyoxyethylenealkylethersulfate salt, and the like. The salt includes alkaline metal salts, ammonium salts, and the like, and examples of the alkaline metal salts are sodium salt, potassium salt, lithium salt, and the like. These emulsifiers may be used solely or in combination with more than two kinds.
Any initiators and chain transfer agents described in the production of the copolymer (A) may be used in the emulsion graft polymerization, and the initiators may be used in the redox polymerization.
To the graft copolymer (B) produced by the emulsion graft copolymerization, a coagulation agent is added to coagulate and recover the latex. The used coagulation agents are acid and aqueous solution of the salt. Examples of the coagulation agents are sulfuric acid, hydrochloric acid,

phosphoric acid, acetic acid, calcium chloride, magnesium chloride, barium chloride, aluminum chloride, magnesium sulfite, aluminum sulfite, aluminum ammonium sulfite, aluminum potassium sulfite, aluminum sodium sulfite, and the like. These coagulation agents may be used solely or in combination with more than two kinds.
The coagulated graft copolymer (B) is added to the copolymer (A) which is preliminarily melt after dehydration and drying. The dehydration and drying are suitably carried out by dehydration of the coagulated slurry or wet cake graft copolymer (B) and then drying in air or nitrogen gas flow, or supplying to an extruder having a groove, hole or gap, and a vent port to make a liquid material pass through. The extruder for dehydration and drying comprises screws, a cylinder, and a screw driver section, and has preferably heating and cooling facilities. The cylinder has grooves, holes, or gaps in the first half section (supply side) that liquid materials can pass through but solids can not, and has at least one vent port in the second half section (discharge side). Either one screw or twin screw extruder can be used. The coagulated slurry or wet cake graft copolymer (B) is supplied to the extruder, compressed by the rotation of the screw in the low temperature region (first half section) of the cylinder so that most water is drained from the grooves, holes, or gaps in the first half section (supply srde) of the cylinder, residual water and volatile materials are removed through the vent port in the heating region of the second

half section (discharge side), and then the dried copolymer is continuously supplied from the cylinder tip to the copolymer. The vent port or plural vent ports may be used at atmospheric pressure or under reduced pressure.
The graft copolymer (B) also may be produced by bulk polymerization. When producing by the bulk polymerization, the melt graft copolymer (B) from the monomer removing equipment directly can be added to the copolymer (A), or the preliminarily melt graft copolymer (B) can be added to the copolymer (A). Generally, the former process is preferably used considering the prevention of heat deterioration and continuous process.
In the present invention, after the graft copolymer (B) is added to the melt copolymer (A) under bulk polymerization process, these copolymers should be mixed else the resin composition having excellent chromaticity and impact resistance is not obtainable. In the process, 90 to 5 phr by weight of the graft copolymer (B) should be continuously added to 10 to 95 phr by weight of the melt copolymer (A), preferably 70 to 5 phr by weight of the graft copolymer (B) to 30 to 95 phr by weight of the melt copolymer (A) is continuously added and mixed:. When the addition of the graft copolymer (B) is carried but at the time of less than 10 percent, preferably less than 5 percent, of the residual monomer content in or after the monomer removing process, further deterioration of the rubber component during the monomer removing process can be prevented so that the

chromaticity and impact resistance being the features of the present invention further improves. The melt mixing after continuous addition of the graft copolymer (B) to the melt copolymer (A) is desirable for satisfactory physical properties such as impact resistance. The melt mixing may be carried out at the time of the graft copolymer addition, or after isolating the mixture, for example at the time of melt forming.
Any continuous addition of the graft copolymer (B) may be used without limitation. In general, various feeders such as belt feeder, screw feeder, one screw extruder, twin screw extruder and the like can be used. Among them, the one screw extruder and twin screw extruder can be preferably used. It is desired that the continuous addition apparatus has weighing mechanism. When the continuous addition apparatus has a heating device, the addition of the graft copolymer (B) in the semi-melt or melt state causes further excellent mixing state. For the purpose, an extruder with heater may be used.
In the present invention, various antioxidants such as phenol antioxidants, phosphorus antioxidants, sulfur antioxidants and the like, ultraviolet absorbers, weather stabilizers such as light stabilizer, antistatic agents, ethylenebisstearylamide, lubricants such as metal salts, plasticizers, coloring agents,~fillers, reinforcing agents such as glass fibers, carbon fibers and the like, fire .retardants and the like may be compounded according to

demand.
The present invention will be explained in detail below using examples, but is not limited to such examples. In the examples, percent(%) and phr represents weight percent and phr by weight, respectively. The YI, i.e. yellow index, value of the pellet was obtained from a color-difference meter made by Suga Shikenki Kabusiki Kaisha. The Izod impact strength and tensile strength were measured according to the ASTM D256 and ASTM 638, respectively.
[REFERENCE EXAMPLE 1: Preparation of a graft copolymer]
A mixture of 50 phr of polybutadiene latex having average diameter of 0.3 &m and containing 85% of gel, 200 phr of pure water, 0.4 phr of sodium formaldehyde sulfoxylate, 0.1 phr of disodium ethylenediaminetetraacetate, 0.01 phr of ferrous sulfate, and 0.1 phr of sodium phosphate was prepared into a reactor, the reactor is replaced with nitrogen gas and maintained at 65 %C, and then a mixture comprising 35 phr of styrene, 15 phr of acrylonitrile, and 0.3 phr of dodecylmercaptan was continuously dropped into the reactor while spending four hours with stirring. At the same time, at a mixture of 0.25 phr of cumene hydroperoxide, 2.5 phr of sodium laurate emulsifier, and 25 phr of pure water was continuously dropped into the reactor while spending four five hours, and the mixture was allowed to stand for further one hour after the dropping so that the polymerization is completed.

A powder graft copolymer (B-l) was prepared by coagulating the reacted latex with 1.5% of sulfuric acid, neutralizing with alkaline, washing,- dehydrating with a centrifuge, and drying up to less than 3% of water content in the hot nitrogen flow using a fluid bed dryer. The graft rate of the obtained copolymer powder (B-l) was 45% by the methyl ethyl ketone extraction method.
[REFERENCE EXAMPLE 2: Preparation of a graft copolymer]
A graft copolymer cake (B-2) containing 60% to 80% of water was prepared by coagulating the latex produced in a similar method with the REFERENCE EXAMPLE 1 with 1.5% of sulfuric acid, neutralizing with alkaline, washing, dehydrating with a centrifuge, and drying using a suction filter.
[REFERENCE EXAMPLES 3 to 9: Preparation of graft copolymers]
Similarly to REFERENCE EXAMPLE 1, graft copolymer powders (B-3 to B-9) having the composition shown in Table 3 were prepared by polymerizing a mixture of styrene and other vinyl monomers in the presence of various rubber polymers. In Table 3, PBD represents the same polybutadiene rubber as that of REFERENCE EXAMPLE 1, SBR represents acrylonitrilebutadiene copolymer rubber comprising 25% of -, acrylonitrile and 75% of butadiene, EPDM represents ethylene-propylene-5-ethylidene-2-norbornene terpolymer rubber (ethylene/propylene molar ratio - 68.5/31.5) having 23 of

iodine value and 60 of Mooney viscosity.
[REFERENCE EXAMPLE 10: Preparation of a graft copolymer]
A latex was obtained similarly to REFERENCE EXAMPLE 1 except for changing the butadiene rubber amount from 50 phr to 70 phr by converting a solid body, styrene amount from 35 phr to 21 phr, and the acrylonitrile amount from 15 phr to 9 phr. 25 phr of styrene was added to 25 phr (corresponding to solid body) of the latex. The mixture was well stirred and then 0.8 phr of magnesium sulfate was added into the mixture. ' The white polymer/monomer layer, i.e. crumb, was taken out from the mixture, and then 20 phr of styrene, 21 phr of acrylonitrile, 0.15 phr of n-dodecylmercaptan, and 0.03 phr of cumene hydroxyperoxide are added into the crumb so that a homogeneous solution, i.e. raw dope was obtained. The raw dope was continuously fed into a polymerizer having a jacket with helical ribbon type stirring wings which was designed so that a condenser and static separator were directly connected at the upper side, water was taken -from the lower layer of the separator out of the system, arid only monomers can be extracted from the upper limit and refluxed to the polymerizer. At a steady state of the continuous polymerization, the reacted mixture containing 75% of polymer was continuously taken out and fed to a twin screw extruder having a vent port. The graft copolymer (B-10) was obtained " by removing the residual monomers from the vacuum vent port at 180 to 240%C.

[REFERENCE EXAMPLE 11: Production method of a graft copolymer]
A graft copolymer (B-ll) containing 15% of rubber component was prepared by dissolving 10 phr of Diene NF35A, a solid butadiene rubber made by Asahi Kasei Kogyo Kabusiki Kaisha, into 90 phr of styrene, continuously bulk-polymerizing and removing a monomer.
[REFERENCE EXAMPLE 12: Production method of a graft copolymer]
A graft copolymer (B-12) containing 10% of rubber component was prepared by dissolving 10 phr of Diene NF35A into 90 phr of a monomer mixture of 70 % of styrene and 30 % of acrylonitrile, continuously bulk-polymerizing and removing a monomer.
[EXAMPLE 1]
Using a continuous bulk polymerizer comprising two vessels shown in Table 1, a preheater, a monomer remover, and a twin screw extruding feeder with a heater tandem connected to the barrel section at one third length from the top of the monomer remover, a monomer mixture comprising 70 phr of styrene, 30 phr of acrylonitrile, and 0.15 phr of n-octylmercaptan is fed into the first vessel at 135 kg/hr so that the continuous bulk polymerization can be proceeded. The polymerizing rates of the first and second vessels are controlled to 58 to 61%, and 90 tO-9L%, respectively through the operation. The polymerized mixture was evaporated at a reduced pressure to remove the residual monomers from the

vent port using an one screw extruding monomer remover. The resulting styrene-acrylonitrile copolymer has 98% of apparent polymerization degree and contains 2% of residual monomer at. the one third from the top of the monomer remover. t-Butylhydroxytoluene (phenolic stabilizer),
tri(nonylphenyl)phosphite (phosphorous stabilizer) and the graft copolymer powder (B-l) prepared in REFERENCE EXAMPLE 1 at a semi-melt state were added at the rate of 0.15 kg/hr, 0.15 kg/hr, and 65 kg/hr, respectively, to the styrene-acrylonitrile copolymer from the twin screw extruding feeder.
After the mixture was melt and kneaded in the monomer remover, the residual monomer was evaporated at a reduced pressure from the vent port so that the apparent polymerization degree becomes more than 99%, and styrene resin composition pellets were produced by cutting the discharged strand product.
The YI value of the obtained styrene resin composition is shown in Table 4. Table 4 also shows the results of the physical properties of the test pieces injected from the styrene resin composition. Table 4 suggests that the styrene resin composition produced by the present invention has excellent chromaticity and physical properties.
[EXAMPLE 2]
Instead of the graft copolymer powder of EXAMPLE 1, the graft copolymer cake produced in REFERENCE EXAMPLE 2 was fed at a rate of 65 kg/hr in a semi-melt state by dehydrating

and drying with an one screw extruder having two gaps and a vent ports to make water pass through. Styrene resin pellets were produced in the same conditions and procedures as EXAMPLE 1. The YI value of the resulting styrene resin composition and the results of physical properties of the test piece prepared from the composition are shown in Table 4. Table 4 demonstrated the styrene resin composition of EXAMPLE 2 also has excellent chromaticity and physical properties.
[EXAMPLES 3 to 12]
Similarly to EXAMPLE 1 except for feeding the graft copolymers (B-3 to B-12) made in REFERENCE EXAMPLES 3 to 12 at a rate shown in Table 4 in the semi-melt state, styrene resin composition pellets were produced by the continuous bulk polymerization and monomer removal of styrene-acrylonitrile, melt kneading the bulk copolymer with the graft copolymers, and discharging the strands. The YI value of each resulting styrene resin composition and the results of physical properties of the test piece prepared from each composition are shown in Table 4. Table 4 demonstrated that each styrene resin composition of EXAMPLE 3 to 12 also has excellent chromaticity and physical properties. [EXAMPLE 13]
Using the continuous bulk polymerizer as EXAMPLE 1, a -monomer mixture comprising 100 phr of styrene and 0^15 phr of t-butylmercaptan was fed at 135 kg/hr into the first vessel to continuously polymerize the monomer. The polymerization

degrees in the first and second vessel were controlled to 67 to 70%, 90 to 91%, respectively during the operation. After preheating the polymerized mixture with the one screw extruding preheater like EXAMPLE 1, the residual monomer was evaporated from the vent port of the twin screw extruding monomer remover under a reduced pressure. The resulting styrene polymer has 96% of apparent polymerization degree and contains 4% of residual monomer at the one third from the top of the monomer remover. t-Butylhydroxytoluene and the graft copolymer (B-5) prepared in REFERENCE EXAMPLE 5 at a semi-melt state were added at the rate of 0.15 kg/hr and 65 kg/hr, respectively, to the styrene polymer from the twin screw extruding feeder. After the mixture was melt and kneaded in the monomer remover, the residual monomer was evaporated at a reduced pressure from the vent port* so that the apparent polymerization degree becomes more than 99% and styrene resin composition pellets were produced by cutting the discharged strand product.
Table 4 shows the results of YI value of the styrene resin composition and the physical properties of the test pieces injected from the composition.
[EXAMPLE 14]
Using a continuous bulk polymerizer comprising the first vessel specified in Table 2, a preheater, a monomer remover, and a twin screw extruding feeder having a heater tandem connect with a barrel section at one -third length from the top of the monomer remover, a mixture comprising 67 phr

of styrene, 33 phr of acrylonitrile, 0.18 phr of n-octylmercaptan, and 0.01 phr of t-butylperoxide were continuously fed into the vessel at a rate of 135 kg/hr to bulk-polymerize. The operation condition was controlled to 74 to 76% of the polymerization degree at the exit of the vessel. After preheating the resulting mixture with the one screw extruding preheater, unreactive monomers were removed by evaporating at a reduced pressure from the vent port of the twin screw extruding monomer remover so that the apparent polymerization degree becomes more than 98% and contains 2% of residual monomer at the one third from the top of the monomer remover, and t-butylhydroxytoluene (phenolic stabilizer), tri(nonylphenyl)phosphite (phosphorous stabilizer) and the graft copolymer powder (B-7) prepared in REFERENCE EXAMPLE 7 at a semi-melt state were added at the rate of 0.15 kg/hr, 0.15 kg/hr, and 65 kg/hr, respectively, to the styrene-acrylonitrile copolymer from the twin screw extruding feeder. After the mixture was melt and kneaded in the monomer remover, the residual monomer was evaporated at a reduced pressure from the vent port so that the apparent polymerization degree becomes more than 99%, and pelletized.
Table 4 shows the results of YI value of the styrene resin composition and the physical properties of the test pieces injected from the composition. •- [EXAMPLE 15] -
Using the same continuous bulk polymerizer as EXAMPLE 14, a monomer/solvent mixture comprising 49 phr of styrene,

21 phr of acrylonitrile, 30 phr of N-phenylmaleinimide, 10 phr of toluene, 0.18 phr of n-octylmercaptan, and 0.01 phr of t-butylperoxide were continuously fed into the vessel at a rate of 150 kg/hr to bulk-polymerize. The operation condition was controlled to 74 to 76% of the polymerization degree at the exit of the vessel. After preheating the resulting mixture with the one screw extruding preheater, unreactive monomers were removed by evaporating at a reduced pressure from the vent port of the twin screw extruding monomer remover so that the apparent polymerization degree becomes more than 98% and contains 2% of residual monomer at the one third from the top of the monomer remover, and t-butylhydroxytoluene (phenolic stabilizer),
tri(nonylphenyl)phosphite (phosphorous stabilizer) and the graft copolymer (B-l) prepared in REFERENCE EXAMPLE 1 at a semi-melt state were added at the rate of 0.15 kg/hr, 0.15 kg/hr, and 65 kg/hr, respectively, to the styrene-acrylonitrile-N-phenylmaleinimide ternary copolymer from the twin screw extruding feeder. After the mixture was melt and kneaded in the monomer remover, the residual monomer was evaporated at a reduced pressure from the vent port so that the apparent polymerization degree becomes more than 99%, and pelletized.
Table 4 shows the results of YI value of the styrene resin composition and the physical properties of the test pieces injected from the composition.
{COMPARATIVE EXAMPLE 1]

Using a continuous bulk polymerizer comprising the two vessels specified in Table 1, a preheater, and a monomer remover, a mixture comprising 70 phr.of styrene, 30 phr of acrylonitrile, and 0.18 phr of n-octylmercaptan, were continuously fed into the first vessel at a rate of 135 kg/hr to bulk-polymerize. The polymerization degrees at the exit of the first and second vessels were controlled to 58 to 61%, and 90 to 91%, respectively, through the operation. The unreactive monomers in the polymerized mixture were removed by evaporating at a reduced pressure from the vent port of the twin screw extruding monomer remover so that the apparent polymerization degree becomes more than 99% and pelletized.
After blending the obtained styrene-acrylonitrile copolymer pellets with the graft copolymer (B-l) produced in REFERENCE EXAMPLE 1 at a composition shown in Table 4, a styrene resin composition was prepared by melt kneading, extruding and pelletizing. Table 4 shows the results of YI value of the styrene resin composition and the physical properties of the test pieces injected from the composition. The chromaticity, i.e. the YI of the pellet, of the styrene resin composition of COMPARATIVE EXAMPLE 1 is inferior to EXAMPLES of the present invention.
[COMPARATIVE EXAMPLE 2]
A mixture comprising 70 phr of styrene, 30 phr of acrylonitrile, and 0.18 phr of t-dodecylmercaptan, were polymerized in a suspension. After blending the obtained styrene-acrylonitrile copolymer beads with the graft

copolymer (Br-1) produced in REFERENCE EXAMPLE 1 at a composition shown in Table 4, a styrene resin composition pellet was prepared by melt kneading, extruding and pelletizing. Table 4 shows the results of YI value of the styrene resin composition and the physical properties of the test pieces injected from the composition. The chromaticity, i.e. the YI of the pellet, of the styrene resin composition of COMPARATIVE EXAMPLE 2 is inferior to EXAMPLES of the present invention.
[COMPARATIVE EXAMPLE 3]
Using the same continuous bulk polymerizer as EXAMPLE 1, a monomer/solvent mixture comprising 49 phr of styrene, 21 phr of acrylonitrile, 30 phr of N-phenylmaleinimide, 10 phr of toluene, 0.18 phr of n-octylmercaptan, and 0.01 phr of t-butylperoxlde was continuously fed into the vessel at a rate of 135 kg/hr to polymerize. The operation was controlled to 74 to 76% of polymerization rate at the exit of the vessel. After the polymerized mixture was preheated with an one screw extruding preheater, the residual mqnomer and toluene were evaporated from the vent port of the. twin screw extruding monomer remover so that the apparent polymerization degree becomes more than 99%, and then pelletized by extruding and cutting a strand. After blending the obtained styrene-acrylonitrile-N-phenylmaleinimide copolymer pellets with the graft copolymer (B-l) produced in REFERENCE EXAMPLE 1 at a -composition shown in Table 4, a styrene resin composition pellet was prepared by melt kneading, extruding and

pelletizing. Table 4 shows the results of YI value of the styrene resin composition and the physical properties of the test pieces injected from the composition. The chromaticity, i.e. the YI of the pellet, of the styrene resin composition of COMPARATIVE EXAMPLE 3 is inferior to EXAMPLES of the present invention.
[COMPARATIVE EXAMPLE 4)
A styrene resin composition was obtained according to the procedure of EXAMPLE 1 except that the feeding rate of the graft copolymer (B-l) was changed to 5 kg/hr. Table 4 shows the results of YI value of the obtained styrene resin composition and the physical properties of the test pieces injected from the composition. The Izod impact strength of the styrene resin composition of COMPARATIVE EXAMPLE 4 is clearly lower than that of EXAMPLES of the present invention.
[COMPARATIVE EXAMPLE 5]
A styrene resin composition was obtained according to the procedure of EXAMPLE 1 except that the feeding rate of the monomer mixture of styrene and aprylonitrile was changed to 9 kg/hr and the feeding rate of the graft copolymer (B-l) was changed to 9 2 kg/hr. Table 4 shows the results of YI value of the obtained styrene resin pomposition and the physical properties of the test pieces injected from the composition. The tensile strength of the styrene resin composition of COMPARAT-IVE EXAMPLE 5 is clearly lower than that of EXAMPLES of the present invention.

1. An impact resistance resin composition comprising: 10 to
95 phr by weight of a copolymer (A) and 90 to 5 phr by weight
of a graft copolymer (B); the copolymer (A) being in a melt
state under a process continuously bulk-polymerizing a
monomer mixture comprising 20 to 100 weight percent of an
aromatic vinyl monomer, 0 to 60 weight percent of a vinyl
cyanide monomer, 0 to 80 weight percent of a (meth)acrylic
acid ester, and 0 to 60 weight percent of another
copolymerizable vinyl monomer; the graft copolymer (B) being
obtained by graft-polymerizing 95 to 20 phr by weight of a
monomer mixture comprising 10 to 100 weight percent of an
aromatic vinyl monomer, 0 to 50 weight percent of a vinyl
cyanide monomer, 0 to 80 weight percent of a (meth)acrylic
acid ester, and 0 to 60 weight percent of another
copolymerizable vinyl monomer in the presence of 5 to 80 phr
by weight of a rubber polymer and the graft copolymer (B)
being continuously added into the copolymer (A) in the melt
state.
2. An impact resistance resin composition according to claim 1, wherein the graft copolymer (B) is obtained by dehydrating and drying slurry or wet cake obtained from an emulsion polymerization latex.
3. An impact resistance resin composition according to claim 1 or claim 2, wherein the graft copolymer (B) is obtained by dehydrating slurry or wet cake obtained from an emulsion polymerization latex and drying slurry or wet cake in the air

or nitrogen gas flow.
4. An impact resistance resin composition according to either of claim 1 to claim 3, wherein the graft copolymer (B) is obtained by dehydrating and drying slurry or wet cake obtained from an emulsion polymerization iatex by supplying to an extruder having a groove, hole or gap and a vent port to make a liquid material pass through.
5. An impact resistance resin composition according to either of claim 1 to claim 4, wherein the graft copolymer (B) is continuously added into the copolymer (A) containing less than 10 weight percent of the residual monomer.
6. An impact resistance resin composition according to
either of claim 1 to claim 5, wherein the graft copolymer (B)
is added to the copolymer (A) in which the residual monomer
content becomes less than 10 weight percent during or after
the monomer removing process of the continuous bulk
polymerization.
i
7. An impact resistance resin composition according to
either of claim 1 to claim 6, whereiki the graft copolymer (B) is added in a grain, semi-melt or melt state.
8. An impact resistance resin composition according to either of claim 1 to claim 7, wherein the rubber polymer of the graft copolymer (B) is a diene rubber.
9. An impact resistance resin composition according to either of claim 1 to claim 8, wherein the copolymer (A) is styrene-acrylonitrile copolymer and the graft copolymer (B) comprises copolymerizing styrene-acrylonitrile to the rubber

polymer.
10. An impact resistance resin composition according to either of claim 1 to claim 9, wherein the monomer removing process of the continuous bulk polymerization of the copolymer (A) is carried out by using an one screw or twin screw extruder having a vent, and the continuous addition apparatus of the graft copolymer (B) is an one screw or twin screw extruder connected with the monomer removing extruder of the copolymer (A).
11. An impact resistance resin composition, substantially as herein described, and exemplified.