JPH0212977B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing a rubber-modified thermoplastic resin. More specifically, the present invention relates to a graft rubber polymer obtained by graft polymerizing a vinyl monomer and a thermoplastic polymer. When producing a rubber-modified thermoplastic resin by mixing the polymer, after mixing the latex of the grafted rubber polymer, the thermoplastic polymer, an organic agent, and a water-soluble agent with coagulation performance, water and a part of the organic agent are mixed. A rubber characterized in that volatile components are separated and removed from the mixture, then a thermoplastic polymer is further melt-mixed into the obtained molten polymer mixture, and the remaining volatile components are separated and removed from the molten polymer mixture. The present invention relates to a method for producing a modified thermoplastic resin. [Prior art] Most rubber-modified thermoplastic resins, typically ABS resins, are produced by graft polymerizing vinyl monomers onto rubber latex and mixing and kneading other thermoplastic resins. It is a resin that has been The manufacturing process usually consists of an emulsion graft polymerization process, a coagulation process, a dehydration/drying process, a blending process, and a melt extrusion process. The emulsion graft polymerization process involves emulsion graft polymerization of acrylic monomers, vinyl cyanide monomers, vinyl aromatic monomers, etc. onto diene rubber latex, vinyl rubber latex, natural rubber latex, silicone rubber latex, etc. This is a process for producing polymer latex. The coagulation step is a step in which a coagulant such as a polyvalent salt or acid is added to the graft polymer latex to break the emulsified state and coagulate the polymer to form a powder. The dehydration and drying process is a process in which the aqueous phase is separated from a mixture of powdered polymer and water by means such as centrifugal dehydration, and then the powder is dried by means such as fluidized drying to obtain dry powder. be. The blending process is a process of blending the dry powder with other thermoplastic resins and additives such as stability agents, lubricants, and plasticizers, and the melt extrusion process involves melting and kneading the blended raw materials using a device such as a screw extruder. This process involves extruding it into strands and shaping it into pellets. The manufacturing and quality problems caused by the rubber-modified thermoplastic resin manufacturing process, which consists of each of the above steps, are as follows:
Firstly, a large amount of heat is used. This is due to the large amount of hot air used in the drying process. The second problem is that the graft rubber particles are completely fixed during the coagulation process, and it takes a lot of effort to completely disperse the fixed graft rubber particles into the thermoplastic resin during the melting and kneading operations after blending. It requires power. Furthermore, in the worst case, it becomes industrially impossible to uniformly disperse the graft rubber particles in the thermoplastic resin. Several proposals have been made to improve the conventional manufacturing method, which includes problems that lead to a decline in industrial competitiveness when manufacturing rubber-modified thermoplastic resins, as described above. is practiced industrially. One of them is aimed at reducing the amount of heat used in the drying process, and uses a screw type extruder with a dehydration function, which is generally called a dehydration extruder. This type of proposed method involves blending the coagulated and dehydrated grafted rubber wet powder with other thermoplastic resins and additives, or feeding the grafted rubber wet powder alone to the dehydrating extruder; and a type in which the graft rubber latex and coagulant are fed to the dewatering extruder together with other thermoplastic resins and additives as the case may be. This type of method does not require a drying process that uses large amounts of hot air, so it can be expected to be effective in terms of reducing the amount of heat used. is on the same level. This is because, in the former method, the graft rubber particles are processed in a completely fixed state, and therefore are equivalent to conventional techniques from the viewpoint of particle dispersion. In the latter case, the latex and coagulant are first mixed in a processing device and then dehydrated at a temperature range of about 100° C. or lower, at which point the grafted rubber particles are usually in a state of being fixed to each other. Thereafter, as the temperature rises, the thermoplastic resin and the thermoplastic resin are melted together and subjected to a kneading operation, so the former method differs only in the state of the supplied raw material, but from the perspective of particle dispersion, it is similar to the former method. It does not leave the realm of old technology. Grafting rubber polymer latex into other methods,
After mixing a coagulant and a monomer to form a two-phase mixture consisting of an organic phase and an aqueous phase, the aqueous phase is separated,
A method of polymerizing the monomers contained in the organic phase and a method of polymerizing the monomers in the two-phase mixture without separating the aqueous phase, then separating the aqueous phase and drying the polymer have been proposed. ing. Since these methods do not involve a process in which the grafted rubber particles completely adhere to each other, they are very unique in terms of dispersion of the particles compared to the above-mentioned method using a dehydrating extruder. However, in the former method, it is necessary to polymerize a highly viscous mixture consisting of a cake-like graft rubber polymer and a monomer without causing a runaway reaction, which is difficult in terms of equipment and operation, and is not necessarily superior. It's hard to say it was a good move. Moreover, in rubber-modified thermoplastic resins, because the content of the rubber component has a great effect on the basic physical properties of the resin, polymerization is not carried out at a low polymerization rate with large polymerization rate fluctuations, as is done in ordinary bulk polymerization methods. It is not possible to use a method of devolatilizing the remaining monomer after completion of the polymerization process, and it is necessary to allow the reaction to proceed until a high polymerization rate is reached, which reduces fluctuations in the polymerization rate. However, it becomes highly viscous and hot, making it extremely difficult to handle. The latter method is a method in which monomers are polymerized by suspension polymerization, and
Although the viscosity of the system is low and the heat of reaction can be easily removed, this method requires dehydration and drying steps, so like the former method, it cannot be said to be the best method. [Problems to be solved by the present invention] As mentioned above, many proposals have been made regarding the production method of rubber-modified thermoplastic resins, but one of the grafted rubber particles, which is essential for the expression of the basic physical properties of the resin, has been proposed. At present, it has not yet been possible to provide a high-quality and competitive method for producing the resin, which solves the problems of dispersion and reduction of the amount of heat used at the same time. In view of the current situation, the present inventors have conducted intensive studies and found a method for producing a rubber-modified thermoplastic resin that does not have the above-mentioned problems, that is, it is possible to more easily disperse grafted rubber polymer particles homogeneously in a thermoplastic polymer. It has been discovered that it is possible to provide a method for producing a rubber-modified thermoplastic resin that is even more energy-saving. [Means for solving the problems] The present invention provides a graft rubber polymer (1) obtained by graft polymerizing a vinyl monomer onto a rubber latex.
0.1 times or more and 6 times or less of the thermoplastic polymer (on a weight basis) based on the total amount of the latex, the thermoplastic polymer (2), the graft rubber polymer (1), and the thermoplastic polymer (2). 2), and has a solubility in water of 5% by weight or less at 25°C (3) and the graft rubber polymer.
The aqueous phase is separated from a two-phase mixture formed by mixing not more than 10% by weight of the latex of the graft rubber polymer (1) with a water-soluble agent (4) capable of coagulating, and then the remaining organic phase is used for the first step. separating the organic agent (3) and a portion of the remaining moisture by thermal means,
After removal, a thermoplastic polymer (5) is further melt-mixed into the resulting molten polymer mixture, and as a second step, the remaining organic agent (3) is separated and removed. This is a method for producing thermoplastic resin. Rubber latexes that can be used in the present invention include all those that have been conventionally used as raw materials for rubber-modified thermoplastic resins, including diene rubber latexes such as polybutadiene, polyisoprene, and SBR, and ethylene-propylene rubber latexes. Examples include latex of rubber, olefin rubber such as ethylene-vinyl acetate rubber, latex of acrylic rubber such as polyethyl acrylate and polybutyl acrylate, and latex of silicone rubber such as polydimethylsiloxane. These rubber latexes can be used alone or in combination of two or more. Furthermore, the present invention does not restrict the type of rubber in any way; latexes other than those listed above may be used as long as they are polymer latexes that have rubber elasticity within the operating temperature range of the rubber-modified thermoplastic resin to be manufactured. It goes without saying that it is possible. The rubber particles contained in the rubber latex as described above are processed using the conventional method.
It is extremely difficult to uniformly disperse the rubber into a thermoplastic resin, and even if it were possible, satisfactory physical properties would not be achieved due to poor compatibility between the rubber and the thermoplastic resin. Therefore, graft polymerization is carried out as a means to improve compatibility, enable dispersion of rubber particles, and exhibit excellent physical properties. The monomer used in this graft polymerization is a vinyl monomer because the polymerization method is emulsion or radical polymerization, and it is optimal from the viewpoint of compatibility with the thermoplastic resin to be blended, adhesiveness, etc. Generally, one is selected. This situation does not change in the present invention. Therefore, the vinyl monomers graft polymerized to rubber that can be used in the present invention include conventionally used vinyl cyan monomers such as acrylonitrile and methacrylonitrile, and vinyl aromatic monomers such as styrene and alphamethylstyrene. These include group monomers, methacrylates such as methyl methacrylate and phenyl methacrylate, halogenated vinyl monomers such as methyl chloroacrylate and 2-chloroethyl methacrylate, and other radically polymerizable monomers. In the present invention, a thermoplastic polymer (2), an organic drug (3), and a water-soluble drug having coagulation properties (4) are added to the latex of the graft rubber polymer (1) obtained by emulsion graft polymerization. Need to mix. This operation is unique to the present invention, and usable thermoplastic polymers (2) include all those that are soluble in the organic drug described below. Acrylonitrile-styrene copolymer, acrylonitrile-alphamethylstyrene copolymer, acrylonitrile-alphamethylstyrene-N-phenylmaleimide copolymer,
polystyrene, polymethyl methacrylate, polyvinyl chloride, polycarbonate, polysulfone,
A typical example is polyethylene terephthalate. Furthermore, the organic drug (3) that can be used in the present invention has a solubility in water at 25°C of 5% by weight or less, preferably 2% by weight or less.
It is an organic drug that is present in an amount of not more than 5 g, preferably not more than 2 g, in 100 grams of an aqueous solution at 25° C., and is capable of dissolving the thermoplastic polymer (2). This organic agent (3) is used in an amount of 0.1 to 6 times, preferably 0.2 to 2 times, on a weight basis, relative to the total amount of the graft rubber polymer (1) and the thermoplastic polymer (2). Can be used in In this case, the solubility of organic drug (3) in water is 5% by weight at 25°C.
If it exceeds this amount, a phenomenon will occur in which the aqueous phase of the mixture that separates into two phases becomes cloudy. On the other hand, organic drugs
The amount of (3) used is 0.1 on a weight basis with respect to the total amount of the graft rubber polymer (1) and the thermoplastic polymer (2).
If the amount is less than 6 times, the desired effect of the present invention will not be achieved, and conversely, if the amount of organic drug (3) is more than 6 times the total amount of both polymers (1) and (2), on a weight basis. If used, a large amount of heat would be required to separate the organic drug (3), which is unfavorable from an industrial standpoint. Examples of organic drugs (3) that can be used in the present invention include:
petroleum ether, benzene, toluene, xylene,
Ethylbenzene, diethylbenzene, P-cymene, tetralin, methylene chloride, chloroform,
Carbon tetrachloride, tricrene, chlorobenzene, epichlorohydrin, methyl-n-propyl ketone,
Acetophenone, n-propyl acetate, n-acetate
Examples include non-polymerizable organic agents such as -butyl and 1-nitropropane, and polymerizable organic agents such as styrene, methyl methacrylate and alpha-methylstyrene, but are not limited to these in any way and satisfy the above conditions. Organic chemicals can be used alone or in combination of two or more. Furthermore, the water-soluble agent (4) having coagulation ability that can be used in the present invention may be any water-soluble substance that has the ability to coagulate the latex of the graft rubber polymer (1) used. 10% by weight or less, preferably 3% by weight based on the graft rubber polymer (1) from the viewpoint of not causing a decrease in the quality of the resin to be produced.
It can be used within a range of % by weight or less. Note that the water-soluble drug (4) is generally used in an amount of 0.2% by weight or more. Examples of such substances include aluminum sulfate,
Examples include polyvalent salts such as pressed aluminum, aluminum nitrate, magnesium sulfate, calcium chloride, and calcium nitrate, inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid, and organic acids such as acetic acid and propionic acid. In the present invention, when the latex of the graft rubber polymer (1) as described above, the thermoplastic polymer (2), the organic agent (3), and the water-soluble agent (4) having coagulation ability are mixed, the mixture becomes a graft rubber polymer. An organic phase consisting of a polymer (1), a thermoplastic polymer (2), an organic drug (3), and a small amount of a polymerization aid soluble in the organic drug, the water-soluble drug (4), and water. It separates into an aqueous phase consisting of a small amount of water-soluble polymerization aid, etc. From this two-phase mixture, the aqueous phase and organic phase are decanted, centrifuged and dehydrated.
Separate by conventional means such as press dehydration. Furthermore, mainly graft rubber polymers (1) and thermoplastic polymers (2)
By heating the organic phase composed of the organic agent (3) and the organic agent (3), the organic agent (3) contained therein and the remaining trace amount of water are partially devolatilized by a normal devolatilization method. As a result, a molten polymer mixture containing a small amount of the organic drug (3) is obtained, but a part of the molten polymer mixture is dissolved in the organic drug (3), and the viscosity of the molten polymer mixture is The viscosity is lower than that without drug (3). Furthermore, in the present invention, a thermoplastic polymer (5) is further melt-mixed into the obtained molten polymer mixture. Thermoplastic polymers (5) that can be used are the aforementioned thermoplastic polymers used in the presence of an organic agent (3).
There are no restrictions on whether it is the same type as (2) or a different type, and any type of material that can be heated and melted can be used.A typical example is the thermoplastic polymer mentioned above. The same specific examples as union (2) can be mentioned. In addition, when carrying out the present invention, thermoplastic polymer (2)
It is preferable from various aspects if and (5) are the same. Generally, the melt viscosity of a thermoplastic resin containing a grafted rubber polymer differs widely from the melt viscosity of the thermoplastic polymer with which it is mixed, since the grafted rubber polymer particles are non-flowable. A large amount of power is required to melt and mix these two polymers, which have widely different melt viscosities. On the other hand, in the presence of a drug that dissolves the polymer, since the polymer has solution-like properties, even if the polymers have widely different melt viscosities, it is very easy to mix them. In addition, the thermoplastic polymer itself that is mixed contains trace amounts of volatile components such as moisture, volatile polymerization aids, and residual monomers, and these components must be removed as much as possible from the perspective of product quality. Should. However, the present invention is extremely useful as a method of mixing thermoplastic polymers having different melt viscosities with emulsion polymerized polymers and removing unnecessary volatile components that cause deterioration of physical properties. The greatest utility of the present invention is that it provides a method for producing a rubber-modified thermoplastic resin that is lower in cost and more rational than emulsion polymer latex. In other words, from the viewpoint of uniformly dispersing the graft rubber polymer particles into the target product resin, a minimum amount of thermoplastic polymer is melt-mixed with the graft rubber polymer in the presence of an organic agent, and the viscosity is balanced during the devolatilization process. By mixing a new thermoplastic polymer when the organic agent is removed, it is possible to minimize the amount of organic agent used, which in turn minimizes the amount of heat used. By mixing the polymers, the kneading power can be minimized. Furthermore, the method of the present invention has excellent features such as being able to greatly reduce the amount of organic chemicals used in the final product and greatly reducing the amount of residual volatile components in the final product. The reason why the amount of organic chemicals used, which is the first feature of the present invention, can be reduced can be easily understood by considering the operation of adding a large amount of thermoplastic polymer (5) after devolatilizing the organic chemicals. In addition, there are two reasons why the remaining volatile components in the product, which is the second feature, can be reduced. This is due to the phenomenon that the larger the value, the easier the volatilization of volatile components. The second reason is the dilution effect caused by mixing the molten polymer having a small amount of volatile components remaining after devolatilization with the thermoplastic polymer (5) having no volatile components.
Therefore, the method of the present invention makes it possible to uniformly disperse graft rubber polymer particles in a thermoplastic polymer compared to conventional methods, and can produce rubber that is even more energy-saving and has less residual volatile content. This makes it possible to produce modified thermoplastic resins. Furthermore, in the present invention, there is no need to use a dryer that conventionally causes a large amount of heat loss, and production can be performed using equipment with a normal devolatilization function such as a vent type extruder or a thin film type evaporator. Needless to say, this makes a significant contribution to the rubber-modified thermoplastic resin industry in terms of cost. The method of the present invention and the effects brought about by it will be specifically explained below using Examples and Reference Examples. Note that all parts in Examples and Reference Examples are based on weight. [Examples] Example 1 Acrylonitrile and styrene were graft-polymerized to a polybutadiene latex having an average particle diameter of 0.36 μm according to Table 1 to obtain a graft rubber polymer latex. Table 1 Polybutadiene latex 114.3 parts (Polybutadiene 40 parts) Acrylonitrile 15 parts Styrene 45 parts Sodium laurate 0.5 parts Sodium hydroxide 0.01 parts Rongarit 0.2 parts Ferrous sulfate 0.002 parts EDTA-disodium salt 0.1 parts Tertiary butyl hydroper oxide
0.3 parts Lauryl mercaptan 0.3 parts Deionized water 125 parts Polymerization temperature 70°C Polymerization time 240 minutes Meanwhile, a thermoplastic polymer, an acrylonitrile-styrene copolymer, was produced according to Table 2. Table 2 Acrylonitrile 25 parts Styrene 75 parts Asobisisobutyronitrile 0.3 parts Lauryl mercaptan 0.5 parts Poval (degree of polymerization 900) 0.07 parts Sodium sulfate 0.3 parts Water 250 parts Polymerization temperature 75°C Polymerization time 240 minutes After completion of polymerization, obtained The acrylonitrile-styrene copolymer suspension was centrifugally dehydrated and dried at 80°C to obtain a powder of the copolymer. Next, the latex of the grafted rubber polymer
300 parts, 40 parts of the above copolymer powder, 200 parts of toluene
When 1000 parts of a 0.1% by weight dilute aqueous sulfuric acid solution, 0.25 parts of Irganox 1076 (manufactured by Ciba Geigy) (antiaging agent) and 1.25 parts of Armide HT (manufactured by Lion Armor) (molding aid) were mixed, the mixture was mixed. The liquid was separated into an aqueous phase and a cake-like organic phase. Then, the organic phase is taken out and passed between two press rolls to separate the excess aqueous phase. It was supplied to the first supply port. Part of the toluene contained in the polymer is devolatilized from the first vent port, 110 parts of the copolymer powder is added from the second resin supply port provided immediately after that, and The remaining toluene was devolatilized through the vent port, and the polymer was shaped into pellets. At this time, the ratio of toluene devolatilization was approximately 3:2 between the first vent and the second vent. The surface of the obtained pellets was smooth, and no uneven portions called bumps were observed. When various test pieces were made by injection molding and various physical property values were measured, the results shown in Table 3 were obtained. These values indicate that the rubber-modified thermoplastic resin produced in this example is excellent.

[Table] *Same for Examples 2, 4, and Reference Examples Example 2 A latex of a grafted rubber polymer was produced using the same chemicals as in Example 1 and according to the formulation in Table 4. Table 4 Polybutadiene latex 228.6 parts (Polybutadiene 80 parts) Acrylonitrile 5 parts Styrene 15 parts Sodium laurate 0.4 parts Sodium hydroxide 0.01 parts Rongarit 0.15 parts Ferrous sulfate 0.001 parts EDTA-disodium salt 0.05 parts Tertiary butyl peroxide 0.2 parts Lauryl mercaptan 0.15 parts Deionized water 50 parts Polymerization temperature 70°C Polymerization time 280 minutes 60 parts of the grafted rubber latex, 30 parts of the acrylonitrile-styrene copolymer used in Example 1
When 40 parts of ethylbenzene and 40 parts of 1% by weight magnesium sulfate were mixed in a continuous kneading device, the mixed liquid separated into two phases as in Example 1. The acrylonitrile-styrene used in Example 1 is continuously supplied to an extruder having a devolatilization section, a second supply port, and a second devolatilization section in order, and after dehydration and a first devolatilization operation, the acrylonitrile-styrene used in Example 1 is supplied from the second supply port. 71 parts of the copolymer was added and a second volatilization operation was performed to form pellets. At this time, the devolatilization ratio of ethylbenzene is approximately 1:1 for the first devolatilization to the second devolatilization.
The surface of the pellets obtained in Example 1 was smooth and no lumps were observed. This pellet was injection molded to create various test pieces, and Example 1
When various physical properties were measured using the same procedure as in
The results shown in the table were obtained. These values indicate that the rubber-modified thermoplastic resin produced in this example is excellent.

[Table] Example 3 Methyl methacrylate and methyl acrylate were graft-polymerized to SBR rubber latex having an average particle diameter of 0.15 μm according to Table 6 to obtain a latex of a grafted rubber polymer. Table 6 SBR rubber latex 100 parts (SBR rubber 50 parts) Methyl methacrylate 45 parts Methyl acrylate 5 parts Potassium rosinate 1 part Rongalite 0.2 parts Ferrous sulfate 0.003 parts Disodium EDTA 0.1 parts Kyumene hydroperoxide 0.4 parts Octyl mercaptan 0.2 parts Deionized water 150 parts Polymerization temperature 65°C Polymerization time 240 minutes Meanwhile, polymethyl methacrylate, which is a thermoplastic polymer, was produced according to Table 7. Table 7 Methyl methacrylate 100 parts Azobisisobutyronitrile 0.3 parts Lauryl mercaptan 0.5 parts Pobol (degree of polymerization 900) 0.07 parts Sodium sulfate 0.25 parts Water 200 parts Polymerization temperature 80°C Polymerization time 180 minutes Obtained after polymerization A suspension of polymethyl methacrylate was centrifugally dehydrated and dried at 80°C to obtain a powder of the polymer. Next, the graft rubber polymer latex 90
When 10 parts of polymethyl methacrylate powder, 20 parts of chloroform, and 300 parts of a 0.2% by weight dilute aqueous magnesium sulfate solution were continuously mixed, the mixture was separated into an aqueous phase and a rice cake-like organic phase. Therefore, using the apparatus used in Example 2, after performing aqueous phase separation and the first devolatilization operation of chloroform in the apparatus, the polymethyl methacrylate powder was subsequently fed from the resin supply port provided in the apparatus. After continuously adding 60 parts and melt-kneading and performing a second devolatilization operation, the polymer mixture was shaped into pellets. The surface of the pellets obtained at this time was smooth,
The existence of the thing was not recognized. The pellets were then injection molded to create various test pieces.
When various physical property values were measured, the results shown in Table 8 were obtained. These results show that the rubber-modified thermoplastic resin produced in this example is excellent.

[Table] Example 4 37.5 parts of the latex of the grafted rubber polymer obtained in Example 2 and 7 parts of a 1% by weight sulfuric acid aqueous solution were added to the first supply port, the second supply port, the dehydration section, the first devolatilization section, and the The first part of the twin-screw kneading extruder has three supply ports and a second devolatilizing section.
It was continuously supplied from the supply port. This mixture is the second
By the time it reaches the supply port, it has been converted into a creamy state, and from the second supply port, 10 parts of dichloromethane and the acrylonitrile-styrene copolymer used in Example 1 are added.
When 12.5 parts were added continuously, the mixture was separated into an aqueous phase and a cake-like organic phase. Next, the aqueous phase is discharged from the dehydration section, a part of dichloromethane is volatilized from the first devolatilization section, and then the third
Polycarbonate resin (Novarex) from the supply port
7022 (manufactured by Mitsubishi Chemical Industries, Ltd.) was continuously added and melt-mixed with the mixture of the graft rubber copolymer and the acrylonitrile-styrene copolymer, and the remaining dichloromethane was volatilized from the second devolatilizing section. At this time, the ratio of dichloromethane volatilized from the first and second devolatilizing sections was approximately 1:4. Further, the obtained mixture was extruded through a nozzle and shaped. This pellet contains 10.0% polybutadiene.
% by weight, and no lumps were observed. Table 9 shows the test results of standard specimens obtained by injection molding the pellets.

[Table] Reference Example 1 The latex of the grafted rubber polymer produced in Example 1 was coagulated with sulfuric acid by a conventional method, and the obtained wet polymer powder was washed, dehydrated, and dried to obtain a dry grafted rubber polymer powder. . This graft rubber polymer, the acrylonitrile-styrene copolymer produced in Example 1, and a small amount of the additive used in Example 1 were mixed and processed into pellets using a screw extruder. The composition of the pellets obtained at this time was the same as that of the pellets obtained in Example 1, but there were many lumps on the surface, and the pellets had no commercial value. Furthermore, the obtained pellets were injection molded and the same tests as in Example 1 were conducted, and the results shown in Table 10 were obtained.

[Table] [Effects of the Invention] According to the method of the present invention, there is no need to coagulate latex into wet powder, dehydrate it, and dry it.
It is possible to produce cost-competitive rubber-modified thermoplastic resins, especially in that heat losses in dryers can be avoided. In addition, since the present invention separates water using an organic agent, it is easy to drain the water, and there is no problem of clogging of the narrow gap provided in the extruder outer part of the conventional dehydration extruder. Since coalescence is handled, there is no need to consider equipment wear. Furthermore, in the present invention, since the graft rubber polymer particles are dispersed into the thermoplastic polymer in the presence of an organic agent, the graft rubber polymer particles do not stick to each other, making it possible to homogeneously disperse the graft rubber polymer particles. In addition, only a small amount of organic chemicals can be used, and the volatile components in the product can be minimized. In addition, the use of organic chemicals makes it easier to mix polymers with widely different melt viscosities, and the latent heat of vaporization of the chemicals is generally extremely small compared to water, making it possible to ultimately reduce the amount of heat used. Become. This means that a rubber-modified thermoplastic resin with excellent surface appearance and various physical properties and high market value can be produced at low cost.

Claims (1)

[Claims] 1 Latex of the graft rubber polymer (1) obtained by graft polymerizing a vinyl monomer onto a rubber latex, a thermoplastic polymer (2), the graft rubber polymer (1), and the thermoplastic polymer (2). An organic agent (3) that has the ability to dissolve the thermoplastic polymer (2) in an amount of 0.1 to 6 times the total amount on a weight basis, and has a solubility in water of 5% by weight or less at 25°C. ) and 10% by weight based on the graft rubber polymer.
The aqueous phase is separated from a two-phase mixture formed by mixing the rubber latex of the graft rubber polymer (1) with a water-soluble agent (4) capable of coagulating, and then the remaining organic phase is heated as a first step. A thermoplastic polymer (5) is further melt-mixed into the molten polymer mixture obtained after separating and removing the organic agent (3) and a portion of the remaining water by means of a second step. A method for producing a rubber-modified thermoplastic resin, characterized by separating and removing an organic agent (3).