JP5436599B2 - Method for producing copolymer - Google Patents

Description

  The present invention relates to a method for producing a copolymer having a high molecular weight and high productivity.

  When thermoplastic resins such as ABS resin and vinyl chloride resin are used for blow molding applications, vacuum molding applications, (foaming) extrusion molding applications, calendering applications, etc., the viscosity at the time of melting is drastically reduced. There are problems such as deterioration of drawdown at the time of vacuum forming and vacuum forming, reduction of the retention rate of foaming gas at the time of (foaming) extrusion molding, adhesion to the roll at the time of calendering. For this reason, there is a method in which a large amount of highly polar components are copolymerized as a modifier with little decrease in viscosity at the time of melting, thereby suppressing the decrease in viscosity. There are problems such as reduced stability.

  In order to solve this problem, a method is known in which a thermoplastic resin having a high molecular weight is blended to suppress a decrease in viscosity. However, when this high molecular weight thermoplastic resin is produced industrially, there is a problem that it is difficult to produce it in a stable and high production efficiency state.

  A method for producing a high molecular weight copolymer by regulating the dissolved oxygen concentration in the polymerization solution and the critical micelle concentration of the emulsifier is known (Patent Document 1). In addition, a method for producing a high molecular weight thermoplastic resin by defining an intrinsic viscosity and a weight average molecular weight / number average molecular weight ratio is known (Patent Document 2). However, in any of the production methods described in the patent documents, the addition method of the monomer component is batch or divided addition, or there is no description about the addition method. There is a problem that productivity cannot be produced and productivity deteriorates.

JP 2000-26543 A

Japanese Patent Laid-Open No. 11-71433

  An object of the present invention is to provide a method for producing a copolymer having a high molecular weight and high productivity.

  As a result of diligent studies to solve the problems of the prior art, the present inventors continuously polymerized by adding a monomer component and an emulsifier, and a polymerization initiator amount used for polymerization and a single amount during polymerization The inventors have found that the above object can be achieved by defining the continuous addition time of the body component and the emulsifier, and have reached the present invention.

That is, the present invention copolymerizes a monomer component containing an aromatic vinyl monomer, a vinyl cyanide monomer, and, if necessary, other vinyl monomers copolymerizable therewith. This is a production method for obtaining a copolymer having a peak peak molecular weight of 1,000,000 or more, wherein a monomer component and an emulsifier are continuously added over 2 to 6 hours to perform polymerization, and the final polymerization is completed. A method for producing a copolymer, characterized in that the conversion is 97% or more, and the coagulum contained in the obtained copolymer latex is 0.5% by weight or less in terms of solid content of the copolymer latex About.

  According to the present invention, a copolymer having a high molecular weight and high productivity can be produced.

The present invention will be described in detail below.
The copolymer produced in the present invention is a monomer component containing an aromatic vinyl monomer, a vinyl cyanide monomer, and, if necessary, other vinyl monomers copolymerizable with these. Is a copolymer having a peak vertex molecular weight of 1,000,000 or more.

Examples of the aromatic vinyl monomer used in the present invention include styrene, t-butyl styrene, α-methyl styrene, p-methyl styrene, divinyl benzene and the like, and styrene and α-methyl styrene are preferable. . These aromatic vinyl monomers can be used alone or in combination of two or more.

  Examples of the vinyl cyanide monomer include acrylonitrile and methacrylonitrile, and acrylonitrile is preferred. These vinyl cyanide monomers can be used alone or in combination of two or more.

  Other vinyl monomers that can be copolymerized with aromatic vinyl monomers and vinyl cyanide monomers include (meth) acrylic acid ester monomers, maleimide monomers, unsaturated acids, Acid anhydride-containing unsaturated monomer, epoxy group-containing unsaturated monomer, hydroxyl group-containing unsaturated monomer, amide group-containing unsaturated monomer, amino group-containing unsaturated monomer, oxazoline group-containing unsaturated monomer And saturated monomers. It is preferable to use a (meth) acrylic acid ester monomer as the other monomer.

  (Meth) acrylate monomers used as other vinyl monomers include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, (meth) acrylic acid Butyl, 2-ethylhexyl acrylate, phenyl (meth) acrylate, 4-t-butylphenyl (meth) acrylate, bromophenyl (meth) acrylate, dibromophenyl (meth) acrylate, 2, (meth) acrylic acid 2, Examples include 4,6-tribromophenyl, (meth) acrylic acid monochlorophenyl, (meth) acrylic acid dichlorophenyl, (meth) acrylic acid trichlorophenyl, etc., (meth) acrylic acid methyl, (meth) acrylic acid Butyl is preferred.

  Examples of maleimide monomers include maleimide, N-methylmaleimide, N-butylmaleimide, N- (p-methylphenyl) maleimide, N-phenylmaleimide, N-cyclohexylmaleimide, and the like. N-cyclohexylmaleimide is preferred.

  Examples of the unsaturated acid include acrylic acid and methacrylic acid. Examples of the acid anhydride group-containing unsaturated monomer include maleic anhydride, itaconic anhydride, and citraconic anhydride, and maleic anhydride is preferred. Examples of the epoxy group-containing unsaturated monomer include glycidyl methacrylate and allyl glycidyl ether, with glycidyl methacrylate being preferred.

  Examples of hydroxyl group-containing unsaturated monomers include 3-hydroxy-1-propene, 4-hydroxy-1-butene, cis-4-hydroxy-2-butene, trans-4-hydroxy-2-butene, and 3-hydroxy. Examples include 2-methyl-1-propene, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, and 2-hydroxyethyl methacrylate is preferable.

  Examples of the amide group-containing unsaturated monomer include acrylamide and methacrylamide, with acrylamide being preferred. Examples of the amino group-containing unsaturated monomer include acrylic amine, dimethylamino methacrylate, diethylamino methacrylate, and dimethylamino acrylate. Examples of the oxazoline group-containing unsaturated monomer include vinyl oxazoline. The above copolymerizable vinyl monomers can be used singly or in combination of two or more.

  The content of the aromatic vinyl monomer used in the copolymer of the present invention is not particularly limited, but from the viewpoint of the thermal stability of the thermoplastic resin composition after blending the copolymer of the present invention, and the copolymer. From the viewpoint of productivity during polymerization of the polymer, it is preferable that 50 to 95 parts by weight are contained in the total 100 parts by weight of the monomer components, and more preferably 55 to 90 parts by weight.

  The content of the vinyl cyanide monomer used in the copolymer of the present invention is not particularly limited, but from the viewpoint of copolymer productivity and copolymer color tone, the total amount of monomer components is 100%. It is preferable that 5-50 weight part is contained in a part, and it is more preferable that it is 10-45 weight part.

  The content of other copolymerizable vinyl monomers used in the copolymer of the present invention is not particularly limited as long as it does not hinder the purpose of the present invention, but in the total 100 parts by weight of the monomer components. It is preferably contained in an amount of 0 to 45 parts by weight, and more preferably 0 to 35 parts by weight.

  The peak apex molecular weight of the copolymer of the present invention needs to be 1 million or more. When the peak vertex molecular weight is less than 1,000,000, it is impossible to impart desired melt strength and melt elasticity to the thermoplastic resin as a processing aid. Preferably it is 1.5 million or more, More preferably, it is 2 million or more. The peak apex molecular weight is a value measured by gel permeation chromatography (GPC), and is the value of the apex portion having the highest detection frequency on the detected molecular weight distribution. The molecular weight distribution of the copolymer of the present invention (Mw / Mn by gel permeation chromatography (GPC) (where Mw is the weight average molecular weight, Mn is the number average molecular weight)) is productivity (polymerization conditions). From the viewpoint of setting etc.), 5.0 or more is preferable.

  Polymerization of the copolymer of the present invention is performed by using 0.01 to 0.15 parts by weight of the polymerization initiator with respect to 100 parts by weight of the monomer component, and continuously using the monomer component and the emulsifier for 2 to 6 hours. It is necessary to add 0.5% by weight or less in terms of solid content of the copolymer latex.

  Examples of emulsifiers used in the present invention include alkali metal salts of rosin acid, alkali metal salts of fatty acids, alkali metal salts of aliphatic alcohol sulfates, alkali metal salts of alkylallyl sulfonic acids, alkali metal salts of dialkyl sulfosuccinic acid esters, Examples thereof include sulfuric acid ester alkali metal salts of polyoxyethylene alkyl (phenyl) ether, and phosphoric acid ester alkali metal salts of polyoxyethylene alkyl (ether). The use amount of the emulsifier is preferably 1 to 5 parts by weight with respect to 100 parts by weight of the total amount of monomer components used for the polymerization, from the viewpoints of the polymerization reaction rate, reaction stability, and appropriate latex viscosity.

  As the polymerization initiator used in the present invention, persulfates, organic hydroperoxides, and the like can be used. In particular, it is preferable to use a persulfate from the viewpoint of latex stability. The amount of the polymerization initiator used is 0.01 to 0.15 parts by weight with respect to 100 parts by weight of the total amount of monomer components used for polymerization, from the viewpoint of adjusting the polymerization reaction initiation behavior and the peak peak molecular weight. It is necessary to be. If it is less than 0.01 part by weight, there are problems that the polymerization does not start stably and the polymerization conversion rate during the polymerization decreases. Moreover, when it exceeds 0.15 weight part, it is difficult to make the molecular weight of the copolymer obtained high.

  Although there is no restriction | limiting in particular in the usage-amount of water used in the case of emulsion polymerization, it is the range of 100-250 weight part with respect to 100 weight part of total amounts of the monomer component used for superposition | polymerization reaction time From the viewpoint of heat control and productivity improvement.

  The polymerization temperature at the time of carrying out the emulsion polymerization is preferably 45 to 80 ° C., more preferably 50 to 75 ° C. from the viewpoints of stability at the start of polymerization and adjustment of the molecular weight. In the polymerization, it is preferable from the viewpoint of stable productivity that the internal temperature is kept constant within this polymerization temperature range.

  As a method for adding the monomer component and the emulsifier during the polymerization of the copolymer, the monomer component and the emulsifier can be mixed in advance and then added continuously, or the monomer component and the emulsifier can be added separately. It is also possible to add them continuously (a plurality of monomers may be added separately). When continuously adding the monomer component and the emulsifier separately, the supply rate of the monomer component and the emulsifier is adjusted, and the composition ratio of the monomer component and the emulsifier from the start of the continuous addition to the end of the continuous addition (continuous addition) Maintaining the weight ratio of the monomer component and the emulsifier used in the process, that is, making the time for adding the monomer component and the emulsifier continuously added from the viewpoint of polymerization stability and formation of a coagulated product. preferable.

  In the present invention, if the monomer component used for polymerization is up to 20% by weight and the emulsifier is up to 60% by weight, it can be added to the reaction vessel as necessary before continuously adding these components. You can leave it. In that case, the ratio of the monomer component and the emulsifier added at the initial stage does not need to maintain the composition ratio as the component used for polymerization, but the weight ratio between the monomer components is finally obtained. It is preferable to maintain the composition ratio. For example, when the polymerization is carried out using 75 parts by weight of an aromatic vinyl monomer, 25 parts by weight of a vinyl cyanide monomer and 2 parts by weight of an emulsifier as monomers used for the polymerization, the monomer added at the initial stage The component and the emulsifier can be 3 parts by weight of an aromatic vinyl monomer, 1 part by weight of a vinyl cyanide monomer, and 1 part by weight of an emulsifier.

  In the production method of the present invention, it is necessary to continuously add the monomer component and the emulsifier over 2 to 6 hours. When the continuous addition time is less than 2 hours (including batch polymerization), the heat generated by the polymerization heat is large, so that not only is the control of the polymerization temperature difficult, but it is included in the copolymer latex obtained after the polymerization. The amount of coagulum increases, the polymerization conversion rate during polymerization decreases, and the productivity is impaired. Similarly, when divided addition is performed, there are problems that the amount of coagulum contained in the copolymer latex increases, and the polymerization conversion rate during polymerization decreases. If the continuous addition time is longer than 6 hours, it is difficult to increase the molecular weight of the copolymer.

  In the present invention, from the viewpoint of productivity, the final polymerization conversion rate is preferably 97% or more, and more preferably 98% or more.

  When the polymerization is completed, the amount of coagulum contained in the copolymer latex is an indicator of productivity, but the coagulum in the present invention is filtered using a 100 mesh wire mesh, The filtration residue obtained by drying is shown. From the viewpoint of productivity, the coagulated product must be 0.5% by weight or less with respect to 100% by weight of the solid content of the copolymer latex. If the amount is more than 0.5% by weight, the coagulated product adheres to the polymerization tank during polymerization, making it difficult to remove the heat of polymerization, and it takes time to remove the coagulated product adhering to the polymerization tank. There arises a problem of significant loss. Preferably it is 0.3 weight% or less, More preferably, it is 0.1 weight% or less.

  The peak apex molecular weight of the copolymer of the present invention can be adjusted by adjusting the amount of the chain transfer agent (including no addition). It is preferable to adjust by the continuous addition time.

  When the copolymer of the present invention is polymerized, the polymerization activity is lowered due to the influence of dissolved oxygen in the latex. Therefore, it is necessary to sufficiently replace nitrogen or use an oxygen removing agent such as hydrosulfite. preferable. The oxygen concentration before polymerization is preferably 6 mg / l or less, more preferably 5 mg / l or less.

  The copolymer of the present invention can be mixed with other thermoplastic resins by converting the obtained copolymer latex through recovery steps such as coagulation, washing and dehydration, and then drying to form a powder. As a coagulant used in the coagulation step, sulfuric acid, magnesium sulfate, calcium chloride, aluminum sulfate, or the like is used as an aqueous solution. One type can be used alone or two or more types can be used. Further, a recovery and drying method using a spray dryer or an atomizer can be used without using a coagulant.

  The copolymer of the present invention can be used as a modifier for other thermoplastic resins. Here, as other thermoplastic resins, ABS resins, AES resins, ASA resins, SAS resins, PS resins, HIPS resins, AS resins and other (rubber reinforced) styrene resins, vinyl chloride resins, chlorinated polyethylene resins, The molding stability of the base thermoplastic resin (composition) is remarkably improved by using ethylene-vinyl acetate resin or a base thermoplastic resin (composition) using two or more of these resins. Is possible. It is preferable to blend 0.1 to 15 parts by weight of the copolymer with respect to 100 parts by weight of the base thermoplastic resin (composition), and it is more preferable to blend 0.5 to 12 parts by weight.

  Depending on the purpose, the base resin may be a resin other than those described above, such as polypropylene, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyamide, polyamide elastomer, epoxy resin, polyvinylidene fluoride, polysulfone, polyisoprene, natural rubber. Thermoplastic resins such as chlorinated butyl rubber, PPE resin, PPS resin, polyether ether ketone, styrene-maleic anhydride copolymer may be used.

  The following additives can be blended in the copolymer of the present invention as needed. Antioxidants such as 2,6-di-t-butyl-4-methylphenol, 2- (1-methylcyclohexyl) -4,6-dimethylphenol, 2,2'-methylene-bis- (4-ethyl- 6-t-butylphenol), 4,4'-thiobis- (6-tert-butyl-3-methylphenol), dilauryl thiodipropionate, tris (di-nonylphenyl) phosphite; UV absorbers such as p T-butylphenyl succinate, 2,2'-dihydroxy-4-methoxybenzophenone, 2- (2'-hydroxy-4'-n-octoxyphenyl) benzotriazole; lubricants such as waxes, paraffin waxes, stearic acid , Hydrogenated oil, stearylamide, methylenebisstearylamide, ethylenebisstearylamide, n-butyls Allate, ketone wax, octyl alcohol, lauryl alcohol, hydroxystearic acid triglyceride; flame retardants such as antimony trioxide, aluminum hydroxide, zinc borate, tricresyl phosphate, tris (dichloropropyl) phosphate, chlorinated paraffin, tetrabromo Bisphenol A, condensate of tetrabromobisphenol A and epichlorohydrin; antistatic agents such as stearylamidopropyldimethyl-β-hydroxyethylammonium nitrate; colorants such as titanium oxide, carbon black; fillers such as calcium carbonate, clay, Silica, glass fiber, glass sphere, carbon fiber; foaming agents such as lower hydrocarbons such as propane, butane, pentane, hexane, methyl chloride, dichloromethane, Halogen hydrocarbons such as lichloromonofluoromethane and dichlorodifluoromethane, carbon dioxide and nitrogen.

  The thermoplastic resin composition in which the copolymer of the present invention is blended is an extruder, in which the copolymer and the base thermoplastic resin (composition) are sufficiently mixed with a mixer or the like without being previously melt-heated and mixed. Injection molding machine, sheet molding machine, vacuum forming machine, profile forming machine, foam molding machine, blow molding machine directly into resin molded products, or using various extruders, Banbury mixers, kneaders, rolls, etc. After melting and mixing the copolymer and the base thermoplastic resin (composition), using an extrusion molding machine, injection molding machine, sheet molding machine, vacuum molding machine, profile forming machine, foam molding machine, blow molding machine It is possible to mold a resin molded product. Preferably, the respective components are directly fed into the molding machine without being melted and mixed in advance. Various molded articles obtained by the molding method can be used for various parts such as home appliances and automobile parts by utilizing their excellent properties.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the examples, “parts” and “%” are based on weight.

Measurement of peak apex molecular weight A gel permeation chromatograph (LC-10A vp) column manufactured by Shimadzu Corporation used GMH HR-H (30) manufactured by Tosoh Corporation. Calibration was performed based on polystyrene standards, and tetrahydrofuran was used as the solvent, and measurement was performed at a flow rate of 0.5 ml / min and a temperature of 50 ° C.
A measurement sample was prepared by placing 0.01 g of a measurement target and 25 ml of tetrahydrofuran in a 50 ml glass flask, sealing it, soaking it at 25 ° C. for 12 hours, and then filtering with a membrane filter having a pore size of 3.0 μm.
The peak apex molecular weight is a numerical value obtained by quantifying the value of the apex portion having the highest detection frequency on the detected molecular weight distribution.

Measurement of the amount of coagulum in the copolymer latex The copolymer latex is filtered through a 100 mesh wire net, the filtration residue is dried, the weight of the filtration residue is measured, and the copolymer latex The amount of coagulum was determined.
Amount of coagulum in copolymer latex (%)
= (Weight after drying of filtration residue (g) / solid content of copolymer latex (g)) × 100

Example 1
After 120 parts of ion exchange water was added to the reactor, nitrogen substitution was performed to remove dissolved oxygen in the system. Thereafter, the temperature of the reactor was raised to 60 ° C., and 0.07 part of potassium persulfate was added as a 3% aqueous solution as a polymerization initiator. Thereafter, 75 parts of styrene, 25 parts of acrylonitrile and 1.5 parts of potassium oleate were made into a 5% aqueous solution, and a mixture of each component was continuously added at 60 ° C. for 4 hours, followed by polymerization at 60 ° C. for 3 hours. The final polymerization conversion rate of the obtained copolymer latex was 99%. The obtained copolymer latex was salted out, dehydrated and dried to obtain a copolymer. The peak copolymer molecular weight of the obtained copolymer was 2,650,000, and the amount of coagulum in the copolymer latex was 0.1%.

Example 2
After adding 120 parts of ion exchange water and 0.4 part of potassium oleate as a 5% aqueous solution to the reactor, nitrogen substitution was performed to remove dissolved oxygen in the system. Thereafter, 3 parts of styrene, 1 part of acrylonitrile and 0.03 part of sodium pyrophosphate as a reducing agent, 0.03 part of glucose, and 0.002 part of ferrous sulfate were dissolved in 5 parts of ion-exchanged water and added. The temperature of the reactor was raised to 60 ° C., and 0.015 part of cumene hydroperoxide was added as a polymerization initiator. Thereafter, 72 parts of styrene, 24 parts of acrylonitrile, 1.6 parts of potassium oleate, 5% aqueous solution, 0.085 parts of 3% aqueous solution of cumene hydroperoxide (total amount of cumene hydroperoxide is 0.1 part) The mixture of each component was continuously added at 60 ° C. for 2.5 hours, and then polymerization was performed at 60 ° C. for 3 hours. The final polymerization conversion rate of the obtained copolymer latex was 98.5%. The obtained copolymer latex was salted out, dehydrated and dried to obtain a copolymer. The peak copolymer molecular weight of the obtained copolymer was 5.25 million, and the amount of coagulum in the copolymer latex was 0.3%.

Example 3
After adding 120 parts of ion exchange water and 0.3 part of potassium oleate as a 5% aqueous solution to the reactor, nitrogen substitution was performed to remove dissolved oxygen in the system. Thereafter, 2.4 parts of styrene, 0.6 part of acrylonitrile, and 1 part of methyl methacrylate were added, and then the reactor was heated to 60 ° C., and 0.08 part of potassium persulfate as a polymerization initiator was 3%. Added as an aqueous solution. Thereafter, 57.6 parts of styrene, 14.4 parts of acrylonitrile, 24 parts of methyl methacrylate and 1.2 parts of potassium oleate were added as a 5% aqueous solution, and a mixture of each component was continuously added at 60 ° C. for 4 hours. Polymerization was carried out at 60 ° C. for 3 hours. The final polymerization conversion rate of the obtained copolymer latex was 99%. The obtained copolymer latex was salted out, dehydrated and dried to obtain a copolymer. The peak copolymer molecular weight of the obtained copolymer was 2.3 million, and the amount of coagulum in the copolymer latex was 0.1%.

Example 4
After adding 120 parts of ion exchange water and 0.4 part of potassium oleate as a 5% aqueous solution to the reactor, nitrogen substitution was performed to remove dissolved oxygen in the system. Then, after adding 3.5 parts of styrene, 1 part of acrylonitrile, 0.5 parts of methyl methacrylate, the temperature of the reactor was raised to 50 ° C., and 0.06 part of potassium persulfate as a polymerization initiator was 3%. Added as an aqueous solution. Thereafter, 66.5 parts of styrene, 19 parts of acrylonitrile, 9.5 parts of methyl methacrylate and 1.6 parts of potassium oleate as a 5% aqueous solution, and a mixture of each component was continuously added at 50 ° C. for 3.5 hours. Thereafter, polymerization was carried out at 50 ° C. for 3 hours. The final polymerization conversion rate of the obtained copolymer latex was 98.5%. The obtained copolymer latex was salted out, dehydrated and dried to obtain a copolymer. The peak copolymer molecular weight of the obtained copolymer was 3,870,000, and the amount of coagulum in the copolymer latex was 0.2%.

Example 5
After adding 120 parts of ion exchange water and 0.3 part of sodium dodecylbenzenesulfonate as a 5% aqueous solution to the reactor, nitrogen substitution was performed to remove dissolved oxygen in the system. Thereafter, 2.6 parts of styrene, 0.75 part of acrylonitrile, and 1.65 parts of methyl methacrylate were added, the reactor was heated to 50 ° C., and 0.04 part of potassium persulfate was added as a polymerization initiator. Added as a 3% aqueous solution. Thereafter, 49.4 parts of styrene, 14.25 parts of acrylonitrile, 31.35 parts of methyl methacrylate and 1.2 parts of sodium dodecylbenzenesulfonate were made into a 5% aqueous solution, and the mixture of each component was added at 50 ° C to 3.5. The addition was continued for a period of time, followed by polymerization at 50 ° C. for 3 hours. The final polymerization conversion rate of the obtained copolymer latex was 98%. The obtained copolymer latex was salted out, dehydrated and dried to obtain a copolymer. The peak copolymer molecular weight of the obtained copolymer was 5.13 million, and the amount of coagulum in the copolymer latex was 0.2%.

Example 6
After adding 120 parts of ion exchange water and 0.3 part of potassium oleate as a 5% aqueous solution to the reactor, nitrogen substitution was performed to remove dissolved oxygen in the system. Then, after adding 3 parts of styrene and 1 part of acrylonitrile, the temperature of the reactor was raised to 50 ° C., and 0.12 part of potassium persulfate was added as a 3% aqueous solution as a polymerization initiator. Thereafter, 72 parts of styrene, 24 parts of acrylonitrile and 1.2 parts of potassium oleate were made into a 5% aqueous solution, and a mixture of each component was continuously added at 50 ° C. for 6 hours, followed by polymerization at 50 ° C. for 3 hours. The final polymerization conversion rate of the obtained copolymer latex was 99%. The obtained copolymer latex was salted out, dehydrated and dried to obtain a copolymer. The peak copolymer molecular weight of the obtained copolymer was 1,500,000, and the amount of coagulum in the copolymer latex was 0.1%.

Comparative Example 1
After adding 120 parts of ion exchange water and 0.3 part of potassium oleate as a 5% aqueous solution to the reactor, nitrogen substitution was performed to remove dissolved oxygen in the system. Then, after adding 3 parts of styrene and 1 part of acrylonitrile, the temperature of the reactor was raised to 60 ° C., and 0.17 part of potassium persulfate was added as a 3% aqueous solution as a polymerization initiator. Thereafter, 72 parts of styrene, 24 parts of acrylonitrile and 1.2 parts of potassium oleate were made into a 5% aqueous solution, and a mixture of each component was continuously added at 60 ° C. for 3 hours, followed by polymerization at 60 ° C. for 3 hours. The obtained copolymer latex was salted out, dehydrated and dried to obtain a copolymer. The final polymerization conversion rate of the obtained copolymer latex was 99%. The peak copolymer molecular weight of the obtained copolymer was 900,000, and the amount of coagulum in the copolymer latex was 0.1%.

Comparative Example 2
After 120 parts of ion exchange water was added to the reactor, nitrogen substitution was performed to remove dissolved oxygen in the system. Then, after adding 50 parts of styrene, 14 parts of acrylonitrile, 36 parts of methyl methacrylate and 1.4 parts of sodium dodecylbenzenesulfonate as a 5% aqueous solution, the temperature of the reactor was raised to 65 ° C., and the polymerization initiator was used. Polymerization was carried out for 6 hours by adding 0.05 part of potassium persulfate as a 3% aqueous solution. The final polymerization conversion rate of the obtained copolymer latex was 94%. The obtained copolymer latex was salted out, dehydrated and dried to obtain a copolymer. The peak copolymer molecular weight of the obtained copolymer was 4,800,000, and the amount of coagulum in the copolymer latex was 1.0%.

Comparative Example 3
After adding 120 parts of ion exchange water and 0.3 part of potassium oleate as a 5% aqueous solution to the reactor, nitrogen substitution was performed to remove dissolved oxygen in the system. Thereafter, 2.4 parts of styrene, 0.6 part of acrylonitrile, and 1 part of methyl methacrylate were added, and then the reactor was heated to 60 ° C., and 0.08 part of potassium persulfate as a polymerization initiator was 3%. Added as an aqueous solution. Thereafter, 57.6 parts of styrene, 14.4 parts of acrylonitrile, 24 parts of methyl methacrylate and 1.2 parts of potassium oleate were added as a 5% aqueous solution, and a mixture of each component was continuously added at 60 ° C. for 8 hours. Polymerization was carried out at 60 ° C. for 3 hours. The final polymerization conversion rate of the obtained copolymer latex was 99%. The obtained copolymer latex was salted out, dehydrated and dried to obtain a copolymer. The peak copolymer molecular weight of the obtained copolymer was 980,000, and the amount of coagulum in the copolymer latex was 0.1%.

Comparative Example 4
After adding 120 parts of ion exchange water and 0.3 part of potassium oleate as a 5% aqueous solution to the reactor, nitrogen substitution was performed to remove dissolved oxygen in the system. Thereafter, 2.4 parts of styrene, 0.6 part of acrylonitrile and 1 part of methyl methacrylate were added, and then the temperature of the reactor was raised to 60 ° C., and 0.008 part of potassium persulfate as a polymerization initiator was 3%. Added as an aqueous solution. Thereafter, 57.6 parts of styrene, 14.4 parts of acrylonitrile, 24 parts of methyl methacrylate and 1.2 parts of potassium oleate were added as a 5% aqueous solution, and a mixture of each component was continuously added at 60 ° C. for 4 hours. Polymerization was carried out at 60 ° C. for 3 hours. However, since the polymerization did not start and the polymerization conversion rate did not increase, a copolymer latex could not be obtained.

Comparative Example 5
After 120 parts of ion exchange water was added to the reactor, nitrogen substitution was performed to remove dissolved oxygen in the system. Then, after adding 25 parts of styrene, 7 parts of acrylonitrile, 18 parts of methyl methacrylate and 1.5 parts of potassium oleate as a 5% aqueous solution, the temperature of the reactor was raised to 60 ° C., and persulfuric acid was used as a polymerization initiator. 0.05 parts of potassium was added as a 3% aqueous solution, and polymerization was carried out at 60 ° C. for 2 hours. Then, after adding 25 parts of styrene, 7 parts of acrylonitrile, and 18 parts of methyl methacrylate, the temperature was raised again, and polymerization was further performed for 5 hours after reaching 60 ° C. The final polymerization conversion rate of the obtained copolymer latex was 95%. The obtained copolymer latex was salted out, dehydrated and dried to obtain a copolymer. The peak copolymer molecular weight of the obtained copolymer was 4 million, and the amount of coagulum in the copolymer latex was 0.8%.

As shown in Table 1, Examples 1 to 6 are production examples of the copolymer according to the present invention, and it can be seen that high molecular weight copolymers are produced efficiently.
On the other hand, in Comparative Example 1 where the amount of initiator used was greater than 0.15 parts by weight, the peak apex molecular weight of the copolymer did not exceed 1 million. Further, in Comparative Example 4 where the initiator was less than 0.01 part by weight, the polymerization did not start, and a copolymer could not be obtained. In Comparative Example 2 in which polymerization was performed in an initial batch without continuously adding monomer components (the continuous addition time was less than 2 hours), the peak apex molecular weight exceeded 1 million, but the amount of coagulum was 0.5. The result was inferior in productivity because it was more than%. In Comparative Example 3 in which the continuous addition time exceeded 6 hours, the amount of coagulum was small, but the peak vertex molecular weight did not exceed 1 million. In Comparative Example 5 in which the continuous addition was not performed and the partial addition was performed, the peak apex molecular weight exceeded 1 million, but the amount of coagulum was more than 0.5%, resulting in poor productivity.

  Since the molecular weight is high by the production method of the present invention, a copolymer that can be blended into other thermoplastic resins and used as a modifier can be obtained with high productivity. Therefore, the industrial value of the present invention is great.

Claims (1)

Peak peak molecular weight obtained by copolymerization of monomer components including aromatic vinyl monomers, vinyl cyanide monomers, and other vinyl monomers copolymerizable with these if necessary Is a production method for obtaining a copolymer of 1 million or more, using 0.01 to 0.15 parts by weight of a polymerization initiator with respect to 100 parts by weight of the monomer component, and the monomer component and the emulsifier Is continuously added over 2 to 6 hours to carry out the polymerization, and the final conversion rate at the end of the polymerization is 97% or more, and the solidified substance contained in the obtained copolymer latex is converted into the solid content of the copolymer latex. And 0.5% by weight or less, a method for producing a copolymer.