JPS6246564B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for producing thermoplastic resin. More specifically, the present invention provides a resin composition having excellent heat resistance, impact resistance, and color tone that can be mixed with a diene-based graft copolymer and suitably used in automobile parts, industrial parts, home appliance parts, etc. The present invention relates to a method for industrially advantageously producing a thermoplastic resin that provides the following properties under controlled conditions. Conventional technology Thermoplastic resin obtained by graft polymerizing acrylonitrile and styrene to rubber whose main component is butadiene is known as ABS resin.
Because it has excellent properties such as processability, mechanical strength, surface gloss, and chemical resistance, it is widely used in many fields today, and as its application fields expand, demand for it is also increasing. It is in. With the expansion of such fields of use, the performance requirements are becoming increasingly strict, and one of these is the need for products with further improved heat resistance. Conventionally, as a method to improve the heat resistance of ABS resin, some or all of the styrene was
- It is known to replace it with methylstyrene. For example, in order to obtain a resin with excellent heat resistance,
It has been proposed to replace styrene with methyl methacrylate and α-methylstyrene (Japanese Patent Publication No. 49-37415). However, even though the heat resistance is improved by introducing α-methylstyrene, the polymerization rate decreases significantly as the amount increases, and the processability and impact resistance deteriorate, making it difficult for ABS resins to In addition, there is a limit to the improvement in heat resistance that can be achieved by introducing α-methylstyrene, and therefore this material is used in modern automobile parts that require heat resistance. It is not necessarily satisfactory for the intended use. Furthermore, in order to obtain a copolymer with excellent impact resistance and heat resistance, it has been proposed to react a rubber component with maleimide, an olefinic unsaturated nitrile, and an aromatic vinyl compound (U.S. Patent No.
3721724 specification). However, when a polymerization reaction of maleimide or the like is carried out in the presence of a rubber component, the polymerization rate decreases significantly, the amount of copolymer that does not participate in bonding with the rubber component increases, and its molecular weight becomes low. In order to easily avoid this and impart the desired heat resistance, increasing the amount of maleimide requires increasing the polymerization time;
Moreover, there are problems such as only molded articles having poor impact resistance and surface gloss can be obtained. On the other hand, a copolymer obtained by emulsion polymerization of α-methylstyrene, a vinyl cyanide monomer, and maleimide or a derivative thereof, and an aromatic vinyl monomer in the presence of polybutadiene or a butadiene copolymer,
A method for producing a composition comprising a vinyl cyanide monomer and a graft copolymer obtained by graft copolymerizing maleimide or its derivative
-135210), multicomponent copolymers obtained by emulsion polymerization of α-methylstyrene, acrylonitrile, N-phenylmaleimide, and other copolymerizable vinyl monomers, and rubber-like polymers. After polymerizing aromatic vinyl monomers, methacrylic acid alkyl ester monomers, vinyl cyanide monomers, N-phenylmaleimide, and other copolymerizable vinyl monomers in the presence of A composition obtained by mixing the obtained graft copolymer with the obtained graft copolymer is disclosed (Japanese Patent Application Laid-open No. 184243/1983). However, in the former production method, when emulsion copolymerizing the copolymer, the amount of usable maleimide or its derivative is added in order to add the entire amount of α-methylstyrene and vinyl cyanide monomer before the start of polymerization. is the amount that can be dissolved in the remaining vinyl cyanide monomer, which is extremely restrictive, and the system tends to become unstable as the polymerization progresses. It has problems such as requiring extremely advanced technology.
In addition, in the latter composition, the multicomponent copolymer is obtained by a normal emulsion polymerization method, but in this case,
For example, if commonly used alkali salts of higher alcohol sulfates or alkylbenzene sulfonic acids are used as emulsifiers, or if persulfates are used as polymerization initiators, the molded product will be brown and colored. It is easy to discolor, and its color tone is inferior to that of ABS resin, and
When using an alkali salt of a higher fatty acid as an emulsifier, or when adding an emulsifier or pure water at a constant rate after the start of polymerization, the polymerization rate decreases significantly and it takes a long time to obtain a high polymerization rate. There is. As described above, it is impossible to industrially produce thermoplastic resins that are blended with diene-based graft copolymers to provide resin compositions with excellent impact resistance, heat resistance, and color tone using known methods. However, at present, the industrial manufacturing technology has not yet been established. Problems to be Solved by the Invention Under these circumstances, the object of the present invention is to provide a resin composition that is blended with a diene graft copolymer and has excellent impact resistance, heat resistance, and color tone. Provided is an industrially advantageous method for producing a thermoplastic resin by an emulsion polymerization method using acrylonitrile, α-methylstyrene, N-arylmaleimide, and other copolymerizable vinyl monomers as desired. There is a particular thing. Means for Solving the Problems As a result of extensive research, the present inventors have found that the above objective can be achieved by controlling the monomer composition, the types of emulsifiers and polymerization initiators, the method of adding various raw materials, etc. We have discovered that this can be achieved, and based on this knowledge, we have completed the present invention. That is, the present invention uses acrylonitrile 10 to 30
wt%, α-methylstyrene 45-75 wt%, N-
Arylmaleimide 5-25% by weight and as desired
When emulsion polymerizing a monomer mixture consisting of 20% by weight or less of other copolymerizable vinyl monomers and in which the weight ratio of N-arylmaleimide to acrylonitrile is 1 or less, an organic hydrochloride is used as a polymerization initiator. A redox catalyst consisting of peroxide and a reducing agent is used as an emulsifier according to the general formula (In the formula, R' and R'' are linear or branched alkyl groups having 4 to 12 carbon atoms, and M is sodium or potassium.) The monomer mixture, organic hydroperoxide and A thermoplastic resin characterized in that a chain transfer agent is added continuously or in divided amounts over a period of 3 to 15 hours so that the amount added at each time is 20% by weight or less of the total amount added, and polymerized. In the present invention, the N-arylmaleimide used as one component of the monomer includes, for example, N-phenylmaleimide, N-methylphenylmaleimide, N-dimethylmaleimide, N-ethylmaleimide. Examples include phenylmaleimide, N-methoxyphenylmaleimide, N-benzylmaleimide, N-naphthylmaleimide, N-chlorophenylmaleimide, N-dichlorophenylmaleimide, etc.
Among these, N-phenylmaleimide is particularly preferred from the viewpoint of industrial availability and price. The amount of N-arylmaleimide used is selected within the range of 5 to 25% by weight based on the total amount of the monomer mixture. If the amount is less than 5% by weight, the desired heat resistance cannot be obtained, and if it exceeds 25% by weight, it becomes difficult to dissolve in other monomer mixtures, making it difficult to continue stable polymerization operation. , when it is made into a thermoplastic resin composition, its color tone is significantly deteriorated. In the present invention, in addition to acrylonitrile, α-methylstyrene, and N-arylmaleimide, other copolymerizable vinyl monomers can be used as desired. Examples of the vinyl monomer include styrene, nuclear-substituted methylstyrene,
Examples include nuclear-substituted dimethylstyrene, nuclear-substituted trimethylstyrene, nuclear-substituted tert-butylstyrene, methacrylonitrile, and methyl methacrylate. The amount of these vinyl monomers used must be selected within a range of 20% by weight or less based on the total amount of the monomer mixture. If more than this is used, the desired heat resistance cannot be obtained. In addition, acrylonitrile and α-methylstyrene each have a content of 10 to 30% relative to the total amount of the monomer mixture.
% by weight and in the range of 45-75% by weight. If the amount of acrylonitrile is less than 10% by weight, it will be difficult to dissolve the N-arylmaleimide and the polymerization rate will also decrease, while if it exceeds 30% by weight, the color tone will deteriorate. Furthermore, if the amount of α-methylstyrene is less than 45% by weight, sufficient heat resistance cannot be obtained, and if it exceeds 75% by weight, the polymerization rate will decrease significantly. Furthermore, in the present invention, in order to enable industrially stable polymerization operation, it is necessary that the N-arylmaleimide be uniformly dissolved in the other monomer mixture, and for that purpose, the N-arylmaleimide must be uniformly dissolved in the other monomer mixture. The amount of arylmaleimide is 25% of the total amount of monomer mixture.
% by weight or less and at the same time the weight ratio to acrylonitrile must be less than 1. The emulsifier used in the present invention has the following general formula () It is an alkali metal salt of dialkyl sulfosuccinic acid represented by (R′, R″ and M in the formula have the same meanings as above), and specific examples include dibutyl sulfosuccinic acid, dihexyl sulfosuccinic acid, di2-ethylhexyl sulfosuccinic acid, Examples include sodium salts or potassium salts of dioctyl sulfosuccinic acid, dilauryl sulfosuccinic acid, etc. Among these, the sodium salt of di-2-ethylhexyl sulfosuccinic acid is particularly preferred from the viewpoint of industrial availability. In the present invention, a sodium salt or a potassium salt of a higher alcohol sulfate ester having 8 to 18 carbon atoms can be used as an emulsifier in addition to the alkali metal salt of dialkyl sulfosuccinic acid as an emulsifier. For example, octyl sulfate, lauryl sulfate,
Examples include sodium salts or potassium salts such as tetradecyl sulfate, hexadecyl sulfate, and nactadecyl sulfate, and among these, sodium lauryl sulfate is particularly preferred. When using these higher alcohol sulfate ester salts, the amount must be selected to be 70% by weight or less based on the total amount with the above-mentioned dialkyl sulfosuccinate; if more than this is used, the thermoplastic resin composition may deteriorate. if you did this,
The color tone may deteriorate, or it may become difficult to continue stable polymerization operation. The same can be said when other types of emulsifiers are used. The amount of the emulsifier used in the present invention is selected within the range of 0.1 to 2.0 parts by weight per 100 parts by weight of the monomer mixture. If this amount is less than 0.1 part by weight, it is difficult to continue stable polymerization operation, and if it exceeds 2.0 parts by weight, the color tone of the thermoplastic resin composition will deteriorate. In the present invention, it is necessary to use a redox catalyst consisting of an organic hydroperoxide and a reducing agent as a polymerization initiator. Examples of organic hydroperoxides include cumene hydroperoxide, paramenthane hydroperoxide, and diisopropylbenzene hydroperoxide, and examples of reducing agents include sodium formaldehyde sulfoxylate/ferrous sulfate/
Combinations such as disodium ethylenediaminetetraacetate and glucose/sodium pyrophosphate/ferrous sulfate may be mentioned. As a polymerization initiator,
For example, if a persulfate such as sodium persulfate or potassium persulfate, which is commonly used in emulsion polymerization of ABS resin, is used, the color tone of the thermoplastic resin composition will deteriorate, which is not preferable. In the present invention, in order to obtain a high polymerization rate without reducing the polymerization rate, the above-mentioned monomers are placed in an aqueous medium containing the above-mentioned emulsifier and reducing agent while maintaining the polymerization temperature in the range of 50 to 80°C. The polymer mixture, organic hydroperoxide, and chain transfer agent are added continuously or in portions such that the amount added at one time is 20% by weight or less of the total amount added over a period of 3 to 15 hours, and the polymerization reaction is carried out. It is necessary to do so. If the polymerization temperature deviates from the above range, it will be difficult to obtain a high polymerization rate, and if the addition time of the raw materials is less than 3 hours, a high polymerization rate will not be obtained, while if it exceeds 15 hours, the productivity of the resin will decrease. Therefore, it is not desirable. After the addition is complete, the polymerization rate can be further increased by continuing the polymerization reaction at a temperature of 50 to 80°C for an additional 1 to 4 hours. As the chain transfer agent, those commonly used in emulsion polymerization of ABS resins, such as tert-dodecylmercaptan, n-dodecylmercaptan, n-octylmercaptan, etc., can be used. As mentioned above, when the monomer mixture, organic hydroperoxide and chain transfer agent are added continuously or in portions to the aqueous medium, the composition can be constant or can be changed as necessary. However, it is necessary that the weight ratio of N-arylmaleimide to acrylonitrile is always 1 or less. In addition, when adding in portions, it is preferable to divide into equal amounts and add at regular intervals;
If the amount added at one time exceeds 20% by weight of the total amount added,
The polymerization rate decreases, making it difficult to obtain a high polymerization rate. The desired thermoplastic resin can be obtained by salting out, dehydrating, and drying the latex thus obtained. This thermoplastic resin is mixed with a graft copolymer to form a thermoplastic resin composition, which is used as a molding material for various purposes. The graft copolymer is usually obtained by polymerizing a monomer mixture consisting of acrylonitrile, styrene, other copolymerizable vinyl monomers, etc. in the presence of a diene rubber by a conventionally known emulsion polymerization method. The one given is used. When this graft copolymer and the thermoplastic resin are mixed, each may be in the form of latex, granules, or flakes. The thermoplastic resin composition thus obtained may contain antioxidants, ultraviolet absorbers,
Flame retardants, pigments, glass fibers, plastics, and even other thermoplastic resins such as acrylonitrile-styrene copolymers and polycarbonates can be added. This thermoplastic resin composition is usually formed into pellets using an extruder and used as a material for various molded products. Effects of the Invention The method of the present invention is an industrially excellent method, and the thermoplastic resin obtained thereby can be mixed with a diene graft copolymer to exhibit excellent heat resistance, impact resistance, and color tone. It is possible to provide a thermoplastic resin composition having the following properties. Taking advantage of its characteristics, this composition is suitably used as a molding material for automobile parts, industrial parts, household appliance parts, and the like. EXAMPLES Next, the present invention will be explained in more detail with reference to Examples. Production example Production of graft copolymer (A-1) The inside of a reactor equipped with a stirrer was replaced with nitrogen, and 150 parts by weight of pure water and polybutadiene latex (weight average particle size 0.3μ) were added in terms of solid content. 60 parts by weight and 1.5 parts by weight of disproportionated potassium rosinate were added, and the temperature was adjusted to 65°C. Then acrylonitrile 12
parts by weight, 28 parts by weight of styrene, 0.3 parts by weight of kyumene hydroperoxide and 0.3 parts by weight of t-dodecylmercaptan, and 30 parts by weight of pure water;
sodium formaldehyde sulfoxylate
An aqueous solution consisting of 0.03 part by weight, 0.01 part by weight of ferrous sulfate, and 0.02 part by weight of disodium ethylenediaminetetraacetate was continuously fed to the reactor over a period of 5 hours. After the supply of the mixed solution and aqueous solution was completed, polymerization was continued at 65° C. for another hour. After the polymerization was completed, the solid content of the latex was measured and the polymerization rate for acrylonitrile and styrene was calculated to be 95%. This graft copolymer is referred to as (A-1). Example 1, Comparative Example 1 The inside of a reactor equipped with a stirrer was replaced with nitrogen, and 200 parts by weight of pure water, 0.9 parts by weight of sodium di2-ethylhexyl sulfosuccinate, 0.1 part by weight of sodium lauryl sulfate, and sodium formaldehyde sulfoxy Rate 0.03 parts by weight, ferrous sulfate
0.01 part by weight and 0.02 part by weight of disodium ethylenediaminetetraacetate were added, and the temperature was adjusted to 70°C. Next, 6 parts by weight of a mixed solution consisting of 20 parts by weight of acrylonitrile, 65 parts by weight of α-styrene, 15 parts by weight of N-phenylmaleimide, 0.3 parts by weight of kyumene hydroperoxide, and 0.2 parts by weight of t-dodecylmercaptan were added.
Continuously fed to the reactor over time. After the end of the supply, polymerization was continued at 70°C for another hour. After the polymerization was completed, the solid content of the latex was measured and the polymerization rate was calculated to be 97%. This copolymer (B-
1). Similarly, copolymers (B-2) to (B-7) were obtained from monomers having the compositions shown in Table 1. Next, the graft copolymer (A-
1) Latex and copolymers (B-1) to (B-
The latexes of 7) were mixed at a ratio of 30 parts by weight and 70 parts by weight, respectively, in terms of solid content, and then dropped into a 2% aqueous aluminum sulfate solution to coagulate. After dehydration and drying, an antioxidant was added and the pellets were made into pellets using a screw extruder. Test pieces were prepared by injection molding and the physical properties and yellowness index (YI) were measured. Table 1 shows the physical properties and yellowness measurement results. In addition, Izotsu impact strength, tensile strength, elongation, and heating temperature are in accordance with JIS K6871, and yellowness is in accordance with JIS K7103.
I found it according to. The same applies to the following examples.

【table】

[Table] Example 2, Comparative Example 2 Copolymer (B-1) in Example 1 except that the composition and type of emulsifier were changed as shown in Table 2
Copolymer (B-8) ~ under the same polymerization conditions as
(B-13) was obtained. Next, the latex of the graft copolymer (A-1) obtained in the production example and the copolymer (B
The latexes -8) to (B-13) were mixed at a ratio of 30 parts by weight and 70 parts by weight, respectively, in terms of solid content, and then added dropwise to a 2% aqueous aluminum sulfate solution to solidify. After dehydration and drying, an antioxidant was added and the pellets were made into pellets using a screw extruder. Test pieces were made by injection molding and the physical properties and yellowness were measured. Table 2 shows the measurement results of physical properties and yellowness. In addition, when an emulsifier consisting of 0.7 parts by weight of sodium di-2-ethylhexylsulfosuccinate and 0.3 parts by weight of disproportionated potassium rosinate was used, the polymerization rate decreased significantly and the polymerization rate after completion of polymerization was also low, resulting in poor physical properties and yellow color. The measurement of the degree was discontinued.

[Table] Comparative Example 3 The inside of a reactor equipped with a stirrer was replaced with nitrogen, 180 parts by weight of pure water, 0.9 parts by weight of sodium di-2-ethylsulfosuccinate, and 0.1 parts by weight of sodium lauryl sulfate were added, and the temperature was raised to 80°C. The temperature was adjusted to Next, 20 parts by weight of acrylonitrile, α-methylstyrene
65 parts by weight, N-phenylmaleimide 15 parts by weight, t
- A mixed solvent consisting of 0.2 parts by weight of dodecyl mercaptan, an aqueous solution consisting of 20 parts by weight of pure water, and 0.2 parts by weight of sodium persulfate were each continuously supplied to the reactor over a period of 6 hours. After the supply was completed, polymerization was continued at 80° C. for another hour to obtain a copolymer (B-14). After the polymerization was completed, the solid content of the latex was measured and the polymerization rate was calculated to be 94%. Next, the latex of the graft copolymer (A-1) and the latex of the copolymer (B-14) obtained in the production example were mixed at a ratio of 30 parts by weight and 70 parts by weight, respectively, in terms of solid content, and then 2 % aluminum sulfate aqueous solution to solidify it, dehydrate and dry it, then add an antioxidant.
Test pieces were made by injection molding after being made into pellets using a screw extruder, and the yellowness was measured.
It was 93. Comparative Example 4 The inside of a reactor equipped with a stirrer was replaced with nitrogen, and 150 parts by weight of pure water, 0.4 parts by weight of sodium di2-ethylhexyl sulfosuccinate, 0.1 parts by weight of sodium lauryl sulfate, and 0.03 parts by weight of sodium formaldehyde sulfoxylate were added. , ferrous sulfate
0.01 part by weight and 0.02 part by weight of disodium ethylenediaminetetraacetate were added, and the temperature was adjusted to 70°C. Next, 20 parts by weight of acrylonitrile, α-methylstyrene
65 parts by weight of a mixed solution consisting of 65 parts by weight of N-phenylmaleimide, 15 parts by weight of N-phenylmaleimide, 0.3 parts by weight of kyumene hydroperoxide, and 0.2 parts by weight of t-dodecylmercaptan, 50 parts by weight of pure water, and 0.4 parts by weight of sodium di2-ethylhexylsulfosuccinate. and 0.1 part by weight of sodium lauryl sulfate were each continuously fed for 6 hours. 1 more after supply ends
Polymerization was continued at 70°C for an hour to obtain a copolymer (B-15). After the polymerization was completed, the solid content of the latex was measured and the polymerization rate was calculated to be 81%. Comparative Example 5 The emulsifiers were 1.5 parts by weight of sodium di-2-ethylhexyl sulfosuccinate and sodium lauryl sulfate.
A copolymer (B-16) was obtained under the same polymerization conditions as for the copolymer (B-1) in Example 1 except that the amount was changed to 1.0 part by weight. Next, the latex of the graft copolymer (A-1) obtained in the production example and the copolymer (B-
The latexes of 16) were mixed in a ratio of 30 parts by weight and 70 parts by weight, respectively, in terms of solid content, and then added dropwise to a 2% aqueous aluminum sulfate solution to coagulate. After dehydration and drying, an antioxidant was added and the pellets were made into pellets using a screw extruder. Test pieces were made by injection molding, and the yellowness was measured to be 88.

Claims (1)

[Scope of Claims] 1 10 to 30% by weight of acrylonitrile, 45 to 75% by weight of α-methylstyrene, 5 to 25% by weight of N-arylmaleimide, and optionally up to 20% by weight of other copolymerizable vinyl systems. When emulsion polymerizing a monomer mixture in which the weight ratio of N-arylmaleimide to acrylonitrile is 1 or less, a redox catalyst consisting of an organic hydroperoxide and a reducing agent is used as a polymerization initiator, and an emulsifier is used as a polymerization initiator. As, the general formula (In the formula, R' and R'' are linear or branched alkyl groups having 4 to 12 carbon atoms, and M is sodium or potassium.) Add an alkali metal salt of dialkyl sulfosuccinic acid to 100% by weight of the monomer. The monomer mixture, the organic hydroperoxide and the chain are added in an aqueous medium containing the reducing agent and emulsifier at a temperature in the range of 50 to 80°C. Production of a thermoplastic resin characterized by adding a transfer agent continuously or in divided amounts over a period of 3 to 15 hours so that the amount added at each time is 20% by weight or less of the total amount added, and polymerizing. Method.