JPS6310163B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a thermoplastic resin with excellent thermal stability and impact resistance. ABS resin, which is generally represented as an impact-resistant resin, is mainly composed of polybutadiene or styrene-butadiene rubber (SBR), styrene, and acrylonitrile. The industrially carried out methods can be categorized based on the polymerization method, and are broadly divided into emulsion polymerization method, bulk polymerization method, suspension polymerization method, solution polymerization method, bulk suspension two-stage polymerization method, and emulsion bulk polymerization method. . However, the above-mentioned polymerization methods are far from satisfactory in all respects.For example, although emulsion polymerization is excellent in polymerization reaction control and production stability, the amount of water used in the coagulation process, washing process, drying process, etc.
The amount of electricity consumed is large, and it is extremely difficult to remove impurities such as salts or acids that are essential in the coagulation process.
It is also a major cause of color banding during thermoforming. In the bulk polymerization method, the rubber elastomer component must be dissolved in the monomer, so it is not only possible to use soluble rubber, but also the rubber content is limited due to the thickening phenomenon of the polymerization system. Therefore, it is not easy to control the reaction of partial heat generation. Even the suspension polymerization method has problems with dissolution of the rubber elastomer into the monomer, problems with the morphology of the product, and further problems with uneven dispersion of the product in the rubber. Further, in the solution polymerization method, reaction operation and reaction control are easy, but a large amount of utility is required for solvent recovery. The two-stage bulk suspension polymerization method has the same problems as the bulk polymerization method in terms of high viscosity operation in the elastomer dissolution step and polymerization step. In the emulsion bulk polymerization method, once a butadiene-based elastomer is produced, styrene and acrylonitrile are emulsion polymerized to produce a graft polymer, and monomers are extracted from this graft polymer to perform bulk polymerization, but this is the same as in the case of the bulk polymerization method. In addition to the problem of reaction control due to partial heat generation, when the rubber content becomes large, rubber deterioration due to partial heat generation cannot be avoided, which requires painstaking efforts to make the polymerization process continuous and to design the polymerization production equipment. In terms of production, it becomes difficult to switch types. Compared to these various polymerization methods, the emulsion suspension polymerization method has the advantages of the emulsion polymerization method, such as easier control of the polymerization reaction, greater freedom in selecting rubber elastomer components, and the ability to increase the rubber elastomer content. While maintaining its excellent properties, it also eliminates the need for a coagulation process, the resulting resin particles are much larger than those produced by coagulation, making drying easier, and the handling of fine powder prevents dust explosions. This is an excellent production method that can solve all the drawbacks of conventional emulsion polymerization methods, such as eliminating the need for safety measures such as: However, since this method is also a polymerization method that uses an aqueous medium, it requires a drying step, and with the drying methods currently used industrially such as fluidized drying and paddle dryers, it is impossible to avoid the long retention of some powders. do not have. On the other hand, the rubber elastomer component used in impact-resistant resins has the drawbacks of poor thermal stability and weather resistance, deterioration and coloring due to long-term heating, and deterioration of mechanical properties. The present inventors have arrived at the present invention as a result of repeated studies to solve this problem in emulsion suspension polymerization and to obtain an industrially applicable impact resistant resin with excellent thermal stability. The present invention provides a rubber-like polymer latex or a graft copolymer latex obtained by polymerizing an ethylenic monomer or a monomer mixture in the presence of a rubber-like polymer latex; (1) an acidic substance or an electrolyte; (2) an ethylenic monomer or monomer mixture and (3) suspension polymerization by adding a suspension polymerization stabilizer; 0.001% by weight of the polymerized product after the suspension polymerization conversion rate is 50% or more
This is a method for producing an impact-resistant resin with excellent thermal stability, which is characterized by adding the above-mentioned phenolic compound. In the present invention, there is no particular restriction on the order of addition of a partial flocculant such as an acidic substance or an electrolyte substance, an ethylenic monomer or monomer mixture, and a suspension polymerization stabilizer, but adding an acidic substance or an electrolyte substance,
Either the system is partially flocculated and then the ethylenic monomer or monomer mixture and the suspension polymerization stabilizer are added simultaneously, or the system is partially flocculated and the ethylenic monomer or monomer mixture is added. It is preferred that a suspension polymerization stabilizer is then added.
However, it is also possible to first add a suspension polymerization stabilizer, then add an acid or electrolyte substance to partially coagulate the system, and then add the ethylenic monomer or monomer mixture. In the present invention, it is important to add the phenol compound during the suspension polymerization, which allows the phenol compound to be uniformly adsorbed to the polymer particles and also allows the suspension polymerization to proceed smoothly. , the thermal stability of the resulting impact resistant resin is significantly improved. On the other hand, for example, if a phenolic compound is dissolved in the ethylenic monomer to be polymerized in suspension polymerization and added at the same time as the monomer, it is effective in improving thermal stability, but the phenol Because the compound acts as a radical scavenger,
Suspension polymerization does not proceed smoothly, polymerization stability is significantly reduced, and agglomeration is likely to occur. Furthermore, a large amount of ethylenic monomer remains in the obtained polymer and water system, causing problems such as increased production costs and environmental pollution. Also, a method in which a phenolic compound is added before transitioning to a suspended state causes the same problem as in the case of dissolving it in the above-mentioned ethylenic monomer. Further, when other oxidation stabilizers such as phosphite compounds and sulfur-containing compounds are added, there is no problem with suspension polymerization, but a sufficient effect is not observed in terms of the desired improvement in thermal stability. Furthermore, in the method of adding phenolic compounds to wet polymer powder before drying using a mixer such as a V-type blender, ribbon mixer, Henschel mixer, etc., the phenolic compound is not evenly adsorbed to the polymer particles and requires long heating times. Colors unevenly. Note that this method of addition causes similar problems even when phosphite compounds are used. The amount of the phenolic compound added is 0.001% by weight or more, preferably 0.05% by weight or more, based on the polymerization product; if it is less than that, the effect will be small. Phenol compounds can be prepared by dispersing them uniformly in water using a surfactant, or by dissolving them uniformly using a solvent that is insoluble in water but soluble in phenolic compounds, or by dispersing this solution with a surfactant. It is added in the form of a dispersion liquid, which is uniformly dispersed in water. The polymer particles obtained in this way are not only thermally stable at relatively low temperatures for long periods of time, such as during retention in the drying process, but also thermally stable at relatively high temperatures, such as during extrusion molding, roll molding, and injection molding. It is also very good in terms of sex. As mentioned above, the time to add the phenolic compound is during the suspension polymerization, but if the polymerization conversion rate is too low, such as immediately after the suspension polymerization starts, the polymerization will not proceed smoothly, so the suspension polymerization conversion will be delayed. Add after the percentage exceeds 50%. Examples of the phenolic compounds used in the present invention include 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-P-
Cresol, 2,4-dimethyl-6-tert-butylphenol, butylhydroxyanisole, 1,1-bis(4-hydroxyphenyl)cyclohexane, 2,2'-methylenebis(4-methyl-6-tert) syabutylphenol), 2,
2'-methylenebis(4-ethyl-6-tertiarybutylphenol, 4,4'-butylidenebis(3)
-methyl-6-tertiarybutylphenol),
4,4′-thiobis(3-methyl-6-tertiarybutylphenol), tetrakis[methylene-
3(3,5-ditertiary-butyl-4-hydroxyphenyl)propionate]methane, 1,
1,3-tris(2-methyl-4-hydroxy-
Examples include 5-tert-butylphenyl)butane, which may be used alone or in combination of two or more. There is no problem in using other oxidation stabilizers at the same time. In order to uniformly disperse phenolic compounds in water, surfactants are usually used. Examples of surfactants include anionic surfactants such as fatty acid salts, higher alcohol sulfate ester salts, and alkylbenzene sulfonates. , nonionic surfactants such as polyoxyethylene alkyl ether and polyoxyethylene alkyl phenyl ether, gelatin, partially saponified polyvinyl alcohol, polyacrylic acid and its salts, which are also used as suspension polymerization stabilizers, Examples include methyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, polyalkylene oxide, etc., based on 100 parts by weight of the phenolic compound.
It is used in a range of 0.1 to 100 parts by weight. In addition, toluene, water-insoluble solvents used to uniformly dissolve phenolic compounds are
Hydrocarbons such as xylene, ethylenic monomers such as styrene, melts of sulfur-containing compounds with relatively low melting points such as dilauroyl thiodipropylnate, phthalate esters such as dioctyl phthalate, and in special cases, 2. Examples include liquid phenolic compounds such as 4-dimethyl-6-tertiarybutylphenol. The method of the present invention can be applied not only to ABS resins using butadiene-based elastomers, but also to resins using various rubber systems. Examples include natural rubber, butadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, isoprene rubber, chloroprene rubber, ethylene-propylene-butadiene rubber, ethylene-vinyl acetate copolymer, etc., and in some cases, there are small amounts of copolymerizable monomers. It may be copolymerized. Monomers that can be copolymerized with such rubber include aromatic monomers such as styrene, α-methylstyrene, and P-substituted styrene, as well as acrylic esters, methacrylic esters, acrylonitrile, methacrylonitrile,
Examples include lower alkyl acrylate, lower alkoxy acrylate, cyanoethyl acrylate, acrylamide, acrylic acid, and methacrylic acid.
Note that the rubber elastomer may be crosslinked or uncrosslinked, but due to problems such as moldability, in the case of uncrosslinked rubber,
It is preferable to use an appropriate amount of crosslinking agent. When using diene rubber as a rubber elastomer, aromatic monomers such as styrene, α-methylstyrene, and P-substituted styrene derivatives, acrylonitrile, and acrylic esters may be used as vinyl monomers to be graft copolymerized. Preferably, the rubber content is 1 to 60% by weight of the resulting impact resistant resin. As the emulsifier used in emulsion polymerization, known anionic emulsifiers such as disproportionated rosin acid soap, potassium oleate soap, and sodium argylbenzenesulfonate can be used, and as the polymerization initiator, kyumene hydro Redox systems consisting of peroxides such as peroxide and persulfates such as ammonium persulfate, as well as t-butyl hydroperoxide monoreductant systems, may also be used. It is preferable to add a chain transfer agent in emulsion polymerization, and usable chain transfer agents include alkyl mercaptans, alkyl halides, alkyl sulfides, alkyl disulfides,
Thioglycolic acid ester, α-methylstyrene dimer, etc. are used, but alkyl mercaptan is particularly preferred. As the partial flocculant used in the process of moving from the first stage of emulsion polymerization to the next suspension polymerization in the present invention, any acid or water-soluble inorganic salt can be used. mineral acids such as acetic acid, and organic acids (including benzoic acid, salicylic acid, formic acid, and tartaric acid) with a dissociation constant of 10 ^-6 mol/or more. Salts include, but are not limited to, sulfates such as magnesium sulfate and sodium sulfate, chlorides, and acetates. As the suspension polymerization stabilizer, ordinary inorganic dispersants and organic dispersants can be used. Examples of inorganic dispersants include magnesium carbonate and tribasic calcium phosphate. Among organic dispersants, natural and synthetic polymer dispersants include starch, gelatin, acrylamide, partially saponified polyvinyl alcohol, polyacrylic acid and its salts, cellulose, methylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, polyalkylene oxide, Examples include polyvinylpyrrolidone, polyvinylimidazole, and sulfonated polystyrene. Also, as low-molecular dispersants, common emulsifiers such as alkylbenzene sulfonates and fatty acid salts can also be used. Peroxides such as benzoyl peroxide and lauroyl peroxide, and azo compounds such as azobisisobutyronitrile are used as initiators in suspension polymerization. In addition, the impact-resistant resin obtained by the present invention may be used with other resins, such as vinyl polymers such as polypropylene, polystyrene, acrylonitrile-styrene copolymer, polymethyl methacrylate, polyvinyl chloride, polyvinylidene chloride, polycarbonate, heat-resistant resin, etc. By mixing it with plastic polyesters and polyamides, it becomes possible to significantly improve moldability and impact resistance. In the following examples, parts represent parts by weight. Example 1 Polybutadiene latex (solid content)*
80 parts (40 parts) Styrene 25.9 parts Acrylonitrile 9.1 parts Ferrous sulfate 0.0045 parts Dextrose 0.3 parts Qyumene hydroperoxide 0.35 parts Tertiarydodecyl mercaptan 0.35 parts Sodium pyrophosphate 0.15 parts Disproportionated rosinate soap 1.0 parts Caustic soda 0.015 parts Methylene bisnaphthalene sulfonic acid sodium 0.12 parts Deionized water 210 parts (*Sumitomo Nogatatsuku SN-800B solid content 50
%) The mixture with the above composition was charged into a reactor, and after purging the inside of the reactor with nitrogen, the mixture was heated at 70°C with a stirring speed of 200 rpm.
Polymerization was carried out for 2 hours to complete the reaction and obtain a graft polymer latex. The polymerization conversion rate was 92%. The obtained graft polymer latex was cooled to 30°C, 5 times 10% sulfuric acid aqueous solution was added under stirring at 350 rpm to form a highly viscous partial aggregate, and then 18.5 parts of styrene and 6.5 parts of acrylonitrile were added. ,
A mixture of 0.25 parts of lauroyl peroxide and 0.5 parts of tertiary dodecyl mercaptan is added, and then 10 parts of a 3% aqueous solution of methyl methacrylate-potassium acrylate copolymer is added as a suspension polymerization stabilizer. From viscous state to low viscosity state (approximately
10 centipoise). This dispersion was heat-polymerized at 80°C for 1.5 hours (polymerization conversion rate of suspended part 70%), and 0.2 part of 2,2'-methylenebis(4-methyl-6-tertiarybutylphenol) was added to the disproportionated rosin. A solution prepared by uniformly dispersing 0.05 parts of acid soap in 10 parts of deionized water was added, and polymerization was further carried out by heating for 1.5 hours. At this time, the polymerization conversion rate was 97%. After filtering the polymer, it was dehydrated using a basket-type centrifugal dehydrator, and the resulting wet powder was subjected to a continuous drying process using a fluidized fluidized dryer, assuming that the polymer particles would accumulate.
Drying was carried out at 100°C for 20 days using a hot air circulation steam dryer. However, no coloration due to thermal deterioration of the dry powder was observed. In addition, 37.5 parts of the obtained polymer, acrylonitrile-styrene copolymer (ηsp/c (25°C DMF) =
0.61) 62.5 parts, calcium stearate 0.4 parts and ethylene bis stearylamide 0.4 parts were mixed in a 10 volume Henschel mixer at 3000 rpm for 5 minutes, extruded into pellets, and made using a screw injection molding machine (cylinder temperature 220°C, mold A notched Izot impact strength measurement test piece and a 1.5 mm thick flat plate were prepared using a temperature of 60°C), and the Izot impact strength,
and yellowness were measured.
All results were good. These results,
The degree of coloration of the dry powder is shown in Table 1, and it can be seen that the dry powder has excellent thermal stability compared to the comparative example described below. Comparative Example 1 In Example 1, 2,2'-methylenebis(4-
A polymer powder was obtained in the same manner as in Example 1 (polymerization conversion rate 97.5%) except that no methyl-6-tert-butylphenol (methyl-6-tert-butylphenol) was added and evaluated at 100°C.
Coloration was already observed after 5 days of drying, and after 20 days of drying, the polymer powder had completely deteriorated and turned brown, making extrusion impossible. Table 1 shows the results. Comparative Example 2 In Example 1, 2,2′-methylenebis(4
Polymer powder was obtained in the same manner as in Example 1, except that 0.6 part of triphenyl phosphite was used instead of (methyl-6-tert-butylphenol) (polymerization conversion rate 97.1%) and evaluation was performed. However, coloration was observed after drying at 100°C for 10 days. The molded specimens prepared using the polymer powder dried for 20 days had a markedly yellowish color and had low Izot impact strength. Table 1 shows the results. Comparative Example 3 In Example 1, 2,2'-methylenebis(4-
A polymer powder was obtained in the same manner as in Example 1 except that 0.6 part of dilauroyl thiodipropionate was used instead of methyl-6-tert-butylphenol (polymerization conversion rate 97.3%), and evaluation was performed. Ivy, 100℃7
Coloration was observed after one day of drying, and after 20 days of drying, the polymer powder completely deteriorated and turned brown, making extrusion impossible. Table 1 shows the results. Comparative Example 4 0.2 part of 2,2'-methylenebis(4-methyl-6-tertiarybutylphenol) was added to the wet polymer powder obtained in the same manner as in Comparative Example 1, and the mixture was heated for 3000 r in a 10 volume Henschel mixer. After mixing for 10 minutes, evaluation was carried out in the same manner as in Example 1.
Uneven coloring was observed after drying for 10 days at ℃. After drying for 20 days, this degree became even stronger, and the molded specimen became yellowish in color, and its Izot impact strength was also low. table-
1 shows the results. Comparative Example 5 A graft polymer latex was obtained under the same conditions as in Example 1, and 0.2 part of 2,2'-methylenebis(4-methyl-6-tert-butylphenol) was added to the styrene polymer latex in suspension polymerization. The mixture was dissolved in a portion of the monomers and added with stirring to obtain a suspension dispersion in the same manner as in Example 1. This dispersion was polymerized by heating at 80° C. for 5 hours, but the polymerization conversion rate was as low as 82%. Comparative Example 6 A graft polymer latex was obtained under the same conditions as in Example 1, and 5 parts of a 10% aqueous sulfuric acid solution was added under stirring at 350 rpm to form a highly viscous partial aggregate, and then styrene was added. 18.5 parts acrylonitrile
A mixture of 6.5 parts of lauroyl peroxide, 0.25 parts of tert-dodecyl mercaptan, and 0.2 parts of 2,2'-methylenebis(4-methyl-6-tert-butylphenol) was added, followed by suspension polymerization. When 10 parts of a 3% aqueous solution of methyl methacrylate-potassium acrylate copolymer was added as a stabilizer, the system transitioned from a high viscosity state to a low viscosity suspension dispersion. This dispersion was polymerized by heating at 80° C. for 5 hours, but the polymerization conversion rate was as low as 79%. Example 2 A dispersion obtained in the same manner as in Example 1 was heated and polymerized at 80°C for 2 hours (suspension polymerization conversion rate 80%).
A solution obtained by uniformly dispersing 0.3 parts of 6-ditertiabutyl-p-cresol in 10 parts of deionized water using 0.05 parts of disproportionated rosin acid soap was added, and polymerization was further carried out by heating for 1 hour. At this time, the polymerization conversion rate was 96.8%. This was evaluated in the same manner as in Example 1, and the results were good. (Table-1). Example 3 In Example 1, 2,2'-methylenebis(4-
A polymer was prepared in the same manner as in Example 1, except that the amount of methyl-6-tert-butylphenol added was 0.1 part, and 0.05 part of potassium oleate soap was used instead of 0.05 part of disproportionated rosin acid soap. A powder was obtained (polymerization conversion rate 97.2%) and evaluated, and the results were good (Table 1). Example 4 In Example 1, 2,2′-methylenebis(4
-Methyl-6-tertiarybutylphenol) was added to 0.1 part, and disproportionated rosin acid soap was added to 0.05 parts.
Polymer powder was obtained in the same manner as in Example 1 (polymerization conversion rate 97.2%), except that 0.05 part of partially saponified polyvinyl alcohol (Nippon Gosei Kagaku: GOHSENOL KH-17) was used instead of The results were good (Table 1). Example 5 In Example 1, 2,2′- was added to 0.5 part of toluene.
A polymer powder was obtained in the same manner as in Example 1 except that 0.2 part of methylenebis(4-methyl-6-tertiarybutylphenol) was dissolved and added (polymerization conversion rate
97.0%), and the results were good.
(Table 1) Example 6 In Example 5, 2,2'-methylenebis(4-
Methyl-6-tert-butylphenol) 0.2
A polymer powder was obtained in the same manner as in Example 5 (polymerization conversion rate 97.0%) except that 0.3 part of 2,4-tert-butyl-p-cresol was used instead of 1 part of 2,4-tert-butyl-p-cresol, and evaluation was performed. was in good condition. (Table-1) Example 7 In Example 1, 2,2'-
A polymer powder was obtained in the same manner as in Example 1 except that 0.2 part of methylenebis(4-methyl-6-tertiarybutylphenol) was dissolved and added (polymerization conversion rate
97.0%), and the results were good.
(Table 1) Example 8 In Example 5, 2,2'-methylenebis(4
-Methyl-6-tert-butylphenol)
A solution of 0.2 parts dissolved in 0.5 parts of toluene was further added to methyl cellulose (Matsumoto Yushi Marporose M-
Polymer powder was obtained in the same manner as in Example 5 except that 0.05 part of 400) was used, uniformly dispersed in 10 parts of deionized water, and added to the system (polymerization conversion rate 97.1%), and evaluated. was in good condition. (Table-1) Example 9 Polybutadiene latex (solid content)*
90 parts (45 parts) Styrene 24.9 parts Acrylonitrile 10.1 parts Ferrous sulfate 0.005 parts Dextrose 0.16 parts Ciumene hydroperoxide 0.3 parts Tertiarydodecyl mercaptan 0.35 parts Sodium pyrophosphate 0.16 parts Disproportionated rosin acid soap 0.8 parts Caustic soda 0.016 parts Methylene bisnaphthalene sulfonic acid sodium 0.12 parts Deionized water 200 parts (*SN-800B manufactured by Sumitomo Nogatatsu Co., Ltd. Solid content 50
%) A mixture with the above composition was charged into a reactor, and after purging the inside of the reactor with nitrogen, the mixture was heated at 60°C with a stirring speed of 200 rpm.
The reaction was completed by polymerizing for 3 hours to obtain a graft polymer latex. The polymerization conversion rate was 91%. Add 0.4 part of tertiary dodecyl mercaptan to the obtained graft polymer latex, continue stirring, cool to 40°C, and add 5 parts of 10% sulfuric acid aqueous solution under stirring at 350 rpm to obtain a high viscosity. Then, a mixed solution of 14.2 parts of styrene, 5.8 parts of acrylonitrile, 0.15 parts of azobisisobutyronitrile and 10 parts of a 3% aqueous solution of methyl methacrylate-potassium acrylate copolymer as a suspension polymerization stabilizer were added. When added simultaneously, the system transitioned from a high viscosity state to a low viscosity (approximately 10 centipoise) suspended dispersion. This dispersion was polymerized by heating at 80℃ for 2 hours (suspension polymerization conversion rate: 81
%), 2,2'-methylenebis(4-methyl-6-
0.1 part of tertiary butylphenol) was added to 2,4-dimethyl-6, a liquid phenolic compound.
-Dissolved in 0.4 part of tertiary butylphenol,
After adding it to the system, it was further heated and polymerized for 1 hour.
The polymerization conversion rate at this time was 97.3%. Evaluation was carried out in the same manner as in Example 1, and the results were good. (Table 1) Example 10 In Example 9, instead of 0.4 part of 2,4-dimethyl-6-tertiarybutylphenol, 0.5 part of dilauroyl thiodipropionate melted by heating was used.
Polymer powder was obtained in the same manner as in Example 9, except that 0.1 part of 2,2'-methylenebis(4-methyl-6-tertiarybutylphenol) was dissolved in it and added to the system. The conversion rate was 97.3%), and the results were good. (Table 1) Example 11 In Example 9, 2,4-dimethyl-6-ter
Example except that 0.2 parts of dioctyl phthalate was used instead of 0.4 parts of syabutylphenol, and 0.1 part of 2,2'-methylenebis(4-methyl-6-tert-butylphenol) was dissolved therein and added to the system. Polymer powder was obtained in the same manner as in 9 (polymerization conversion rate
97.1%), and the results were good.
(Table 1) Example 12 In Example 9, 2,2'-methylenebis(4-
Methyl-6-tert-butylphenol) 0.1
% of 2,4-dimethyl-6-tertiarybutylphenol was dissolved in 0.4 parts of 2,4-dimethyl-6-tert-butylphenol, and then 0.02 parts of disproportionated rosin acid soap was further dispersed in 10 parts of deionized water, and added to the system. A polymer powder was obtained in the same manner as in Example 9 (polymerization conversion rate 97.2%) and evaluated, and the results were good. (Table-1)

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Claims (1)

[Scope of Claims] 1. A rubbery polymer latex or a graft copolymer latex obtained by polymerizing an ethylenic monomer or a monomer mixture in the presence of a rubbery polymer latex (1) containing an acidic substance; or partial agglomeration with an acidic substance or electrolyte substance in a method of carrying out suspension polymerization by adding an electrolyte substance, (2) an ethylenic monomer or monomer mixture, and (3) a suspension polymerization stabilizer. , and a method for producing an impact-resistant resin with excellent thermal stability, characterized by adding 0.001% by weight or more of a phenolic compound to the polymerization product after the suspension polymerization conversion rate reaches 50% or more. . 2. The manufacturing method according to claim 1, characterized in that the phenol compound is uniformly dispersed in water or dissolved in a solvent and added to the suspension polymerization system.