JPH0218683B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing 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 synthetic rubber with a copolymer latex consisting of an unsaturated acid monomer and an alkyl acrylate in the presence of a large particle diameter rubber latex, in which at least one compound selected from the group of styrene, acrylonitrile and methyl methacrylate was used. A type of monomer and CH ₂ =C< 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 group of The inventors completed the present invention by discovering that a resin composition with even better impact resistance could be obtained by graft polymerizing the obtained large particle size rubber over time. That is, in the present invention, at least one unsaturated acid selected from the group of acrylic acid, methacrylic acid, itaconic acid, and crotonic acid is added to 100 parts by weight (as solid content) of synthetic rubber A latex adjusted to a pH of 7 or higher.
0.1 to 20% by weight, 99.9 to 40% by weight of at least one conjugated diene monomer, and 0 to 47% by weight of at least one other monomer copolymerizable with these.
When enlarging synthetic rubber by adding 0.1 to 5 parts by weight (as solid content) of unsaturated acid-containing copolymer B latex obtained by emulsion polymerization of a monomer group consisting of the unsaturated acid As a latex containing copolymer B, 5 to 90% by weight of the monomer group and a portion not containing the unsaturated acid are polymerized in advance, and then the remaining part of the monomer group containing the unsaturated acid 95
At least one monomer selected from the group of styrene, acrylonitrile, and methyl methacrylate is added in the presence of 7 to 70 parts by weight (as solid content) of the obtained enlarged rubber latex. Grafting monomer 93~, comprising 30% by weight or more of a monomer and 70% by weight or less of at least one monomer having a CH ₂ =C< group copolymerizable therewith.
This is a method for producing a thermoplastic resin with excellent impact resistance, characterized by polymerizing 30 parts by weight. The synthetic rubber used in the present invention includes polybutadiene, a copolymer of 50% by weight or more of butadiene and 50% by weight or less of at least one vinyl monomer copolymerizable therewith, chloroprene and its copolymer, and acrylic acid. Ester homopolymer or 50
Included are copolymers comprising at least 50% by weight of alkyl acrylate and 50% by weight or less of a vinyl monomer copolymerizable therewith. These can be easily obtained by ordinary polymerization methods and have a particle size of about 0.05 to 0.2μ. These synthetic rubbers do not require particular restrictions on polymerization conditions, and may be crosslinked with divinyl compounds or the like. Enlargement of rubber particles can be achieved simply by adding the unsaturated acid-containing polymer B latex to this synthetic rubber A latex, but
Here, it is necessary that the synthetic rubber A latex has a pH of 7 or higher. For example, polybutyl acrylate rubber latex polymerized with sodium octylsulfosuccinate as an emulsifier and potassium persulfate as a catalyst has a pH of 2 to 3, but even if an unsaturated acid-containing polymer latex is added to this latex, no No hypertrophy occurs. However, if a small amount of alkali such as potassium hydroxide is added to raise the pH to 7 or higher, rubber with a large particle size can be easily obtained. The unsaturated acid-containing copolymer used to enlarge the synthetic rubber in the present invention must be in the form of a latex, and must be composed of a specific unsaturated acid and a conjugated diene monomer. are essential conditions, and if necessary, other monomers copolymerizable with these may be copolymerized. The unsaturated acids constituting the unsaturated acid-containing copolymer are selected from the group of acrylic acid, methacrylic acid, itaconic acid, and crotonic acid, and these unsaturated acids are used alone or in combination. The constituent amount of the above unsaturated acid in the unsaturated acid-containing copolymer is 0.1 to 20
It needs to be in weight percent. If the amount is less than 0.1% by weight, the enlarging ability will be low, and if the amount is more than 20% by weight, the enlarging ability will be too strong and excessive particles will be produced, which is not preferable. On the other hand, the conjugated diene monomers constituting the unsaturated acid-containing copolymer include butadiene, chloroprene,
Isoprene and the like are used alone or in combination. The content of the conjugated diene monomer in the unsaturated acid-containing copolymer is from 99.9 to 40% by weight, and if it deviates from this range, the effects of the present invention cannot be sufficiently achieved. Other copolymerizable monomers that may be used if necessary to form the unsaturated acid-containing copolymer include unsaturated aromatic compounds such as styrene, α-methylstyrene, and vinyltoluene; acrylonitrile, and methacrylonitrile. Unsaturated nitrile compounds; examples include alkyl (meth)acrylates in which the alkyl group has 1 to 12 carbon atoms, and these may be used alone or in combination. The amount of the other copolymerizable monomer in the unsaturated acid-containing copolymer is 0 to 47% by weight.
If it exceeds 47% by weight, the effects of the present invention will not be achieved. In the present invention, the above-mentioned unsaturated acid-containing copolymer B latex is prepared by first selecting 5 to 50% of the monomer group consisting of the above-mentioned specific range of unsaturated acid, conjugated diene monomer, and other copolymerizable monomers. After polymerizing the portion having a weight of 90% by weight and not containing the unsaturated acid, the remaining 95 to 10% by weight of the monomer group containing the unsaturated acid may be polymerized to obtain a latex having a two-layer structure. This is necessary, and as a result, the effect of enlarging the synthetic rubber becomes extremely large. On the other hand, it is also possible to simultaneously polymerize a monomer group consisting of an unsaturated acid, a conjugated diene monomer, and other copolymerizable monomers. In this case, the enlargement effect is small, so it is not preferable. In addition, as unsaturated acid-containing monomers or monomers similar thereto, there are the other cinnamic acid, maleic anhydride, butenetricarboxylic acid, etc., but when these are used, their enlargement ability is small, so they are not practical. Not on point. Further, when producing the unsaturated acid-containing copolymer, it is preferable to use an anionic surfactant as an emulsifier, but a nonionic surfactant may also be used. The particle size of the unsaturated acid-containing copolymer latex greatly affects the enlargement ability, and is particularly preferably from 0.05 to
It is in the range of 0.2μ. Further, the particle size of the enlarged rubber obtained by the present invention is 0.2 to 1 μm. This unsaturated acid-containing copolymer is added to a synthetic rubber latex in the form of a latex, and at this time, by simultaneously adding an inorganic electrolyte, the particle size of the synthetic rubber can be enlarged extremely efficiently and stably. The amount of the unsaturated acid-containing copolymer latex added is 0.1 to 5 parts by weight (as solid content), particularly preferably 0.5 to 3 parts by weight, per 100 parts by weight (as solid content) of the synthetic rubber latex. Also, the amount of inorganic electrolyte added is 100% synthetic rubber.
0.05 to 4.0 parts by weight, particularly preferably 0.1 parts by weight
Up to 1.0 part by weight is sufficient, and such a small addition effectively enlarges the synthetic rubber. As the inorganic electrolyte, neutral inorganic salts such as potassium chloride, sodium chloride, and sodium sulfate can be suitably used. Further, this inorganic electrolyte can be added in advance during the polymerization of the synthetic rubber latex, and the same effect as when added at the time of enlargement is achieved. When performing the enlargement treatment of the present invention, it is necessary to maintain the pH of the synthetic rubber A latex at 7 or higher. When the PH value is on the acidic side, even if the unsaturated acid-containing copolymer B latex is added, the enlarging effect is low, and the thermoplastic resin targeted by the present invention cannot be advantageously produced. The pH of the synthetic rubber A latex may be adjusted to 7 or higher during the polymerization of the synthetic rubber, or may be separately carried out before the enlargement treatment. In the presence of 7 to 70 parts by weight (solid content) of the enlarged rubber latex subjected to enlargement treatment in this way,
At least one monomer selected from the group of styrene, acrylonitrile and methyl methacrylate
30 to 100% by weight and CH ₂ =C < which can be copolymerized with this
0 to 70% by weight of at least one monomer having groups
By polymerizing 93 to 30 parts by weight of a grafting monomer consisting of the following, a thermoplastic resin with excellent impact resistance, which is the object of the present invention, can be obtained. Styrene, acrylonitrile, and methyl methacrylate as grafting monomers are used alone or in combination, and account for 30 to 30% of all grafting monomers.
It is used in a range of 100% by weight. Monomers having a CH ₂ =C< group that can be copolymerized with these monomers include aromatic vinyl compounds such as styrene, α-methylstyrene, and vinyltoluene; unsaturated nitriles such as acrylonitrile and methacrylonitrile; Compound; alkyl group has 1 carbon number
-12 alkyl (meth)acrylates, etc., which can be used alone or in combination,
The amount used is up to 70% by weight of the total grafting monomer, and it is not preferable to use it alone as a grafting monomer. Examples of mixtures of monomers for grafting include styrene-acrylonitrile mixtures, styrene-alkyl acrylate mixtures, acrylonitrile-methyl methacrylate, methyl methacrylate-alkyl acrylate mixtures, and acrylonitrile-alkyl acrylate mixtures. A mixture of the above monomers can be used. In this emulsion graft polymerization, commonly known emulsifiers and catalysts are used, and there are no particular restrictions on the type and amount added. In the production method of the present invention, if the content of enlarged rubber in the thermoplastic resin is less than 7% by weight, the impact resistance will be low and there will be no practical value, and if it exceeds 70% by weight, fluidity and processability will deteriorate. Undesirable. 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 content of enlarged rubber in the graft polymer matrix is 7
Although it does not have to be in the range of ~70% by weight, the content of enlarged rubber in the final resin composition after blending is 3% by weight.
It is preferably in the range of ~40% by weight. Examples of rubber-free resins used at this time include polystyrene, polymethyl methacrylate, AS resin, acrylonitrile-α-methylstyrene copolymer, polyvinyl chloride, polycarbonate, and the like. In the present invention, polystyrene means a homopolymer or a copolymer consisting of 50% by weight or more of styrene units. Polymethyl methacrylate means a homopolymer or a copolymer consisting of 50% by weight or more of methyl methacrylate units. Moreover, polyvinyl chloride means a homopolymer or a copolymer consisting of 50% by weight or more of vinyl chloride units. Furthermore, polycarbonate means a homopolymer or a copolymer consisting of 50% by weight or more of carbonate units. When graft polymerizing the enlarged rubber, the graft monomers may be added all at once, or may be added in portions or 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 thermoplastic resin obtained by the method of the present invention has the following advantages compared to conventionally known thermoplastic resins. 1. It is possible to manufacture continuously from rubber polymerization to final resin polymerization. 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 the rubber enlargement process, it is economical and the final resin has good thermal stability. 5. Very little formation of excessive coagulum (coagulum) after rubber enlargement treatment and graft polymerization. 6 By using the unsaturated acid-containing copolymer B latex of the present invention, large particle size synthetic rubber can be easily obtained with a very low unsaturated acid content, and the composition of the unsaturated acid-containing copolymer can be enlarged. Since it is possible to make the composition almost the same as that of the synthetic rubber to be produced, a thermoplastic resin having extremely high impact strength can be obtained. The present invention will be specifically explained below using Examples.
In the examples below, "parts" and "%" mean "parts by weight" and "% by weight," respectively. Example 1 [Synthesis of synthetic rubber] (A-1) 1,3-butadiene 66 parts Butyl acrylate 9 Styrene 25 parts Potassium oleate 1.0 Potassium rosinate 1.0 Diisopropylbenzene hydroperoxide
0.2〃 Ferrous sulfate 0.005〃 Sodium pyrophosphate 0.5〃 Dextrose 0.3〃 Water 200〃 A mixture having the above composition was polymerized at 50°C in a 100° autoclave. Polymerization was almost completed in 9 hours, and a rubber latex with a conversion rate of 97%, a particle size of 0.08 μm, and a pH of 9.0 was obtained. [Synthesis of unsaturated acid-containing copolymer latex for enlargement] (B-1) 1,3-butadiene 60 parts Styrene 20 parts Potassium oleate 0.8〃 Potassium rosinate 0.8〃 Diisopropylbenzene hydroperoxide
0.16〃 Ferrous sulfate 0.004〃 Sodium pyrophosphate 0.4〃 Dextrose 0.24〃 Water 160〃 Using a mixture of the above composition, polymerization was carried out in a 100° autoclave at 50°C. Polymerization was almost completed in 9 hours, and a rubber latex with a conversion rate of 97% and a particle size of 0.08 μm was obtained. To this copolymer: Potassium oleate 1 part Sodium dioctyl sulfosuccinate 3 Cumene hydroperoxide 0.1 Sodium formaldehyde sulfoxylate
0.3〃 10〃 of water was added and the temperature was raised to 70℃, and a mixture consisting of 17 parts of n-butyl acrylate, 3 parts of methacrylic acid and 0.3〃 of cumene hydroperoxide was added dropwise over 1 hour.
Stirring was continued for hours to obtain a copolymer latex with a conversion rate of 98%. [Adjustment of enlarged latex] Synthetic rubber latex (A-1) 100 parts (solid content)
3.0 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 performed 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°C for 4 hours) Add 2 parts of butylated hydroxytoluene and 0.5 part of dilaurylthiopropionate as antioxidants to the obtained polymer latex, and add 5% sulfuric acid. It was coagulated with an aqueous 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 part of butyl stearate, 0.3 parts of stearyl alcohol, and 0.2 parts of Hoechstwax OP. Mixed on a mixing roll at 165°C, then pressure molded at 180°C - 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 emulsion polymerization using the method described below. (B-2) 1,3-butadiene 60 parts Styrene 20〃 n-butyl acrylate 17〃 Methacrylic acid 3〃 Sodium dioctyl sulfosuccinate 2〃 Diisopropylbenzene hydroperoxide
0.2〃 Ferrous sulfate 0.005〃 Sodium pyrophosphate 0.5〃 Dextrose 0.3〃 Water 200〃 A mixture having the above composition was polymerized at 50°C in a 100° autoclave. Polymerization was almost completed in 9 hours, and a rubber latex with a conversion rate of 97% and a particle size of 0.07 μm was obtained.

[Table] As is clear from Table 1, by using a conjugated diene monomer in the first stage and copolymerizing methacrylic acid in the second stage, the acid group-containing latex for enlargement contains very little methacrylic acid. The thickening effect is high depending on the amount, and the stability of the obtained thickened latex is also good. Furthermore, it can be seen that when the graft polymer is blended with PVC, the development of impact strength becomes better. Example 2 As an unsaturated acid-containing copolymer latex for enlargement, the first stage consisted of 75 parts of 1,3-butadiene;
21 parts of butyl acrylate, 4 parts of methacrylic acid
A latex (B-3) consisting of 1. Various synthetic rubbers were enlarged using this, and the monomers shown in Table 2 were graft-polymerized in the presence of 20 parts of these enlarged rubbers. Table 2 shows the impact strength of the products.

【table】

Claims (1)

[Claims] 1 Synthetic rubber A latex adjusted to PH7 or higher
Acrylic acid, per 100 parts by weight (as solid content)
0.1 to 20% by weight of at least one unsaturated acid selected from the group of methacrylic acid, itaconic acid, and crotonic acid, and at least one conjugated diene monomer
Unsaturated acid-containing copolymer B latex 0.1-5 obtained by emulsion polymerization of a monomer group consisting of 99.9-40% by weight and 0-47% by weight of at least one other monomer copolymerizable with these. Parts by weight (as solids)
When enlarging the synthetic rubber by adding , the unsaturated acid-containing copolymer B latex is prepared by polymerizing 5 to 90% by weight of the monomer group and not containing the unsaturated acid. and then polymerize the remaining 95 to 10% by weight of the unsaturated acid-containing monomer group, and in the presence of 7 to 70 parts by weight (as solid content) of the obtained enlarged rubber latex, CH ₂ =C copolymerizable with 30% by weight or more of at least one monomer selected from the group of styrene, acrylonitrile, and methyl methacrylate;
1. A method for producing a thermoplastic resin having excellent impact resistance, which comprises polymerizing 93 to 30 parts by weight of a grafting monomer comprising 70% by weight or less of at least one type of monomer having a group.