JPS6326763B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a new thermoplastic resin having excellent impact resistance. Impact-resistant resins such as ABS resin and high-impact polystyrene are usually obtained by graft polymerizing styrene, acrylonitrile, methyl methacrylate, and other monomers to rubber components.
The composition and structure of the graft copolymer, the rubber content, the polymerization method, etc. greatly influence the physical properties of the final composition. In particular, when graft polymerizing rubber components using emulsion polymerization, it is a widely known fact that the particle size of the base rubber component controls the impact resistance and processability of the final composition. The larger the size, the better the impact resistance and processability of the resulting resin. Therefore, attempts have been made to make the rubber particle size as large as possible, and various proposals have been made so far. The present applicant also previously swelled a diene rubber with a copolymer latex consisting of an unsaturated acid monomer and an alkyl acrylate in the presence of a large particle size rubber latex. Both are a type of monomer and CH ₂ = which can be copolymerized with this monomer.
We proposed a resin composition with good impact resistance obtained by polymerizing a mixture consisting of a monomer having a C Proceeds in a short time,
The present invention was completed based on the discovery that a resin composition with even better impact resistance could be obtained by graft polymerizing the obtained large particle diameter rubber. The present invention is directed to (a) a rubber having a pH of ₇ or higher (A )
For 100 parts by weight of latex (as solid content),
(b) 3 to 30% by weight of at least one unsaturated acid selected from the group of acrylic acid, methacrylic acid, itaconic acid and crotonic acid, and at least one alkyl acrylate whose alkyl group has 1 to 12 carbon atoms 97 Of the monomer (b) consisting of ~35% by weight and 0-48% by weight of other copolymerizable monomers, first polymerize the portion that is 5-90% by weight and does not contain the unsaturated acid. After that, 0.1 to 5 parts by weight (as solid content) of an acid group-containing copolymer (B) latex obtained by polymerizing the remaining 95 to 10% by weight of the monomer (b) containing the unsaturated acid.
(c) at least one selected from the group of styrene, acrylonitrile and methyl methacrylate in the presence of 7 to 70 parts by weight (as solids) of an enlarged rubber latex having a particle size of at least 0.2μ obtained by adding It is characterized by polymerizing 93 to 30 parts by weight of a monomer mixture consisting of 30% by weight or more of one type of monomer and 30% by weight or less of a monomer having a CH ₂ =C< group copolymerizable with the monomer. This is a method for producing a thermoplastic resin with excellent impact resistance. The rubber component (A) is 1.3-polybutadiene or a copolymer containing 50% or more of 1.3-butadiene,
For example, butadiene-styrene, butadiene-
Butadiene-aromatic vinyl compound copolymers such as vinyltoluene copolymers, butadiene-acrylonitrile copolymers, butadiene-methacrylonitrile copolymers, butadiene-methyl acrylate, butadiene-ethyl acrylate, butadiene-butyl acrylate, butadiene-2-
Butadiene-acrylic acid ester copolymers such as ethylhexyl acrylate copolymers, butadiene-methyl methacrylate, butadiene-
It includes butadiene-methacrylic acid ester copolymers such as ethyl methacrylate copolymers, and also terpolymers containing 50% or more of butadiene. These can be easily obtained by commonly known emulsion polymerization. There are no particular restrictions on the catalyst, emulsifier, etc., and the particle size thereof is 0.04 to 0.2μ. A copolymer (B) containing acrylic acid, methacrylic acid, itaconic acid and crotonic acid is then used to thicken the rubber latex. It is essential that this copolymer (B) contains an acid group-containing monomer and an acrylate, and at least one type of alkyl acrylate whose alkyl group has 1 to 12 carbon atoms is selected as the acrylate. It can be done. Even if a monomer such as methacrylate, styrene, or acrylonitrile is used instead of acrylate, no effect is observed. However, it is possible to replace up to half of the acrylate with other monomers. The acid group-containing monomer is used in an amount of 3 to 30% by weight, but if it is less than 3%, the enlargement ability is small;
Also, if it exceeds 30%, the enlargement ability is too strong,
This is not preferable because it generates particles that are larger than 1μ. In addition, the optimal content of the acid group-containing monomer varies depending on the degree of hydrophilicity of the acrylate used. If the acrylate has a high hydrophilicity, the enlargement effect will be reduced in the region where the amount of the acid group-containing monomer is small. On the other hand, if the amount of acid group-containing monomer increases, the latex will be destroyed, which is undesirable.On the other hand, if the hydrophilicity of acrylate is low, areas with a low amount of acid group-containing monomer will have the effect of thickening. is small, and the effect will not be seen unless the amount of the acid group-containing monomer exceeds a certain level.
For example, in the case of highly hydrophilic acrylates such as methyl acrylate and ethyl acrylate, it is optimal when the amount of acid group-containing monomer is 5 to 10%, whereas hydrophobic In the case of butyl acrylate and 2-ethylhexyl acrylate, which are alkyl acrylates, the optimum amount is 13 to 20% of the acid group-containing monomer. However, when a highly hydrophilic acrylate is used, even if the amount of acid group-containing monomer is 5 to 10%, the system tends to become unstable, which leads to the formation of cullets (coarse particles). On the other hand, when hydrophobic acrylates such as those described above are used, the system does not become unstable and uniform enlarged particles can often be obtained. In addition to the above, examples of acid group-containing monomers or similar monomers include cinnamic acid, maleic anhydride,
There are butenetricarboxylic acids and the like, but their use is not practical due to their low enlargement ability. Acid group-containing copolymer (B) used in the present invention
The latex contains 3 to 30% by weight of at least one unsaturated acid selected from the group of acrylic acid, methacrylic acid, itaconic acid and crotonic acid, and at least one alkyl acrylate whose alkyl group has 1 to 12 carbon atoms. Of the monomer (b) consisting of ~35% by weight and 0-48% by weight of other copolymerizable monomers, first polymerize the portion that is 5-90% by weight and does not contain the unsaturated acid. After that, the remaining 95 to 10% by weight of the monomer (b) containing the unsaturated acid must be continuously polymerized without forming new particles, resulting in a latex with a two-layer structure. . This acid group-containing polymer (B) latex is the base rubber (A).
By adding an inorganic electrolyte, preferably an inorganic salt, particularly a neutral inorganic salt, to the latex, the particle size of the base rubber can be enlarged very efficiently and stably. The amount of the acid group-containing polymer (B) latex added is 0.1 to 5 parts by weight, particularly preferably 0.5 to 3 parts by weight, per 100 parts by weight of the base rubber (A). In addition, the inorganic electrolyte is added per 100 parts by weight of the base rubber (A).
Addition of 0.05 to 4 parts by weight, particularly 0.1 to 1 part by weight, will increase the size of the base rubber more efficiently and will greatly improve the stability of the resulting large particle size rubber latex. As the inorganic electrolyte, commonly known inorganic salts such as KCl, NaCl, Na ₂ SO ₄ etc. can be used. Further, this inorganic electrolyte can be added in advance during polymerization of the base rubber latex, and has the same effect as when added during enlargement. When carrying out the enlargement treatment of the present invention, it is necessary to maintain the pH of the base rubber (A) latex at 7 or higher. When the PH value is on the acidic side, even if the acid group-containing copolymer (B) latex is added, the enlargement efficiency is low, and the composition targeted by the present invention cannot be advantageously produced. The pH of the base rubber (A) latex may be adjusted to 7 or higher during the polymerization of the base rubber, or may be adjusted separately before the enlargement treatment. In the presence of 7 to 70 parts by weight of the rubber latex that has been enlarged in this way, the desired impact-resistant resin can be obtained by polymerizing monomers mainly consisting of styrene, acrylonitrile, and methyl methacrylate. . Examples of monomers to be grafted onto the rubber latex include styrene alone, methyl methacrylate alone, styrene-acrylonitrile monomer mixture, styrene-acrylic acid ester monomer mixture, methyl methacrylate-acrylonitrile monomer mixture, and methyl methacrylate-acrylic. Examples include acid ester monomer mixtures, acrylonitrile-acrylic acid ester monomer mixtures, and monomer mixtures of three or more of these monomers. In this emulsion graft polymerization, commonly known emulsifiers and catalysts are used, and there are no particular restrictions on the type and amount added. If the rubber content is less than 7% by weight, the impact resistance is low and there is no practical value, and if it exceeds 70% by weight, fluidity and processability deteriorate, which is not preferable. The preferred rubber content is 10-25% by weight. Further, by blending a resin not containing rubber with the above graft polymer, a resin composition with good impact resistance can be obtained. In this case, the rubber content in the base graft polymer may not be in the range of 7 to 70% by weight, but the final content after blending may be in the range of 7 to 70% by weight. preferable. Examples of rubber-free resins used at this time include polystyrene, polymethyl methacrylate, AS resin, polyvinyl chloride, and polycarbonate. When graft polymerizing the enlarged rubber, the graft monomer may be added all at once, added in portions, added continuously, or each monomer may be graft polymerized individually in stages. Also good. Known antioxidants, lubricants, colorants, fillers, etc. can be added to the resulting graft or graft-blend polymer. The composition obtained by the production method of the present invention has the following advantages compared to conventionally known thermoplastic resin compositions. 1. It is possible to manufacture continuously from the polymerization of the rubber to the polymerization of the final composition. 2 No special equipment is required. 3. Rubber polymerization can be carried out in a short time, resulting in extremely high productivity. 4. Since no specific dispersant or emulsifier is required during rubber enlargement treatment, it is economical and the final composition has good thermal stability. 5. Very little formation of excessive coagulum (coagulum) after rubber enlargement treatment and graft polymerization. 6. Rubber with a large particle diameter (0.4 to 1 μm), which is extremely difficult to obtain using conventional enlargement methods, can be easily obtained, so a composition with extremely high impact strength can be obtained. In the following examples, "parts" and "%" mean "parts by weight" and "% by weight," respectively. Example 1 Synthesis of base rubber (A-1) 1.3-Butadiene 66 parts Butyl acrylate 9〃 Styrene 25〃 Diisopropylbenzene hydroperoxide 0.2 parts Potassium oleate 1.0〃 Potassium rosinate 1.0〃 Sodium pyrophosphate 0.5〃 Ferrous sulfate 0.005 〃 Dextrose 0.3〃 Water 200〃 According to the above composition, autoclave 100 at 50℃
Polymerized with Polymerization was almost completed in 9 hours, and the conversion rate was
A rubber latex with a particle size of 97% and a particle size of 0.08μ was obtained. Acid group-containing copolymer latex for enlargement (B-1)
Synthesis of n-butyl acrylate 25 parts Potassium oleate 2〃 Sodium dioctyl sulfosuccinate 1〃 Cumene hydroperoxide 0.1〃 Sodium formaldehyde sulfoxylate 0.3〃 Water 200〃 After polymerizing the mixture of the above composition at 70°C for 1.5 hours, continue At 70°C, a mixture consisting of 60 parts of n-butyl acrylate, 15 parts of methacrylic acid, and 0.3 parts of cumene hydroperoxide was added dropwise over 1 hour, and then 1
Stirring was continued for hours to obtain a copolymer latex with a conversion rate of 98%. Adjustment of enlarged latex Base rubber latex (A-1) 100 parts (solid content)
1.5 parts (solid content) of latex (B-1) was added to the mixture over 5 seconds while stirring. Table 1 shows the results of measuring particle diameters using an electron microscope for samples taken immediately after stirring this latex for 30 minutes and for samples taken after being left for 5 days. Next, using the enlarged latex obtained by stirring for 30 minutes, graft polymerization was immediately carried out according to the following composition to synthesize a graft polymer. Synthesis of graft polymer (G-1) Enlarged rubber (solid content) 60 parts Styrene 21〃 Methyl methacrylate 19〃 Cumene hydroperoxide 0.16〃 Sodium formaldehyde sulfoxylate 0.1〃 Potassium oleate 1.0〃 Water 200〃 (Polymerization conditions 70 ℃4 hours) 2 parts of butylated hydroxytoluene and 0.5 parts of dilaurylthiopropionate were added as antioxidants to the obtained polymer latex, which was coagulated with a 5% aqueous sulfuric acid solution, washed, and dried to obtain a white powder. . To 10 parts of this powdered resin (G-1) were added 100 parts of polyvinyl chloride (PVC) with a degree of polymerization of 700, 3.0 parts of dibutyl tin malate, 1.0 parts of butyl stearate, 0.3 parts of stearyl alcohol, and 0.2 parts of Hoechstwax OP. , mixed on a mixing roll at 165℃, then
Pressure molded at 180℃-150Kg/ ^cm2 for 15 minutes
When Charpy Impact was measured, the results shown in Table 1 were obtained. For comparison, a similar evaluation was conducted using a latex (B-2) obtained by polymerizing a mixture having the following composition in one step. n-Butyl acrylate 85 parts Methacrylic acid 15 Potassium oleate 2 Sodium dioctyl sulfosuccinate 1 Cumene hydroperoxide 0.4 Sodium formaldehyde sulfoxylate 0.3 Water 200

[Table] As is clear from Table 1, by forming the enlargement agent into a two-layer structure, the particle size can be enlarged more efficiently, and the stability of the obtained enlarged latex can also be improved. Furthermore, it can be seen that when the graft polymer is blended with PVC, the development of impact strength becomes better. Example 2 1 as acid group-containing copolymer latex for enlargement
A latex (B-3) in which the first stage consisted of 20 parts of butyl acrylate and 5 parts of methyl methacrylate and the second stage consisted of 60 parts of butyl acrylate and 15 parts of methacrylic acid was prepared in the same manner as (B-1) in Example 1. Synthesized with. Table 2 shows the impact strength of various synthetic rubbers which were enlarged using this compound and the monomers shown in Table 2 were graft-polymerized in the presence of 20 parts of these enlarged rubbers.

【table】

Claims (1)

[Claims] 1 (a) 100 to 50% by weight of 1,3-butadiene and a monomer having a CH ₂ =C< group that can be copolymerized therewith from 0 to
Rubber (A) latex with a pH of 7 or higher consisting of 50% by weight
3 to 30% by weight of at least one unsaturated acid selected from the group of (b) acrylic acid, methacrylic acid, itaconic acid, and crotonic acid, based on 100 parts by weight (as solid content), Of the monomer (b) consisting of 97 to 35% by weight of at least one kind of alkyl acrylate of 1 to 12 and 0 to 48% by weight of other copolymerizable monomers, first, 5 to 90% by weight of the monomer (b) is An acid group-containing copolymer (B) obtained by polymerizing the portion not containing the unsaturated acid and then polymerizing the remaining 95 to 10% by weight of the monomer (b) containing the unsaturated acid. 7 to 70 parts by weight (as solid content) of enlarged rubber latex with a particle size of at least 0.2 μ obtained by adding 0.1 to 5 parts by weight (as solid content) of latex
(iii) copolymerizable with at least 30% by weight of at least one monomer selected from the group of styrene acrylonitrile and methyl methacrylate;
A method for producing a thermoplastic resin having excellent impact resistance, comprising polymerizing 93 to 30 parts by weight of a monomer mixture comprising 30% by weight or less of a monomer having a CH ₂ =C< group.