JPH0440383B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a thermoplastic resin composition with excellent moldability, color tone, impact resistance, and heat resistance, and more specifically, a graft copolymer of rubber-modified aromatic vinyl and vinyl cyanide, α-methylstyrene and cyanide. The present invention relates to a thermoplastic resin composition containing a copolymer with vinyl chloride and polycarbonate as main components. Generally, ABS resin (acrylonitrile-butadiene-styrene graft copolymer or a mixture of the graft copolymer and a copolymer of aromatic vinyl and vinyl cyanide) has excellent mechanical properties and moldability. However, it is insufficient in terms of heat resistance.
Furthermore, although polycarbonate has excellent heat resistance and mechanical properties, it has the disadvantage of high melt viscosity and poor moldability. In addition, various methods of blending polycarbonate and ABS resin have been proposed as a method for improving the moldability of polycarbonate and the heat resistance of ABS resin (Japanese Patent Publication No. 38-15225,
JP-A-49-99153, JP-A-50-111150). However, the resin compositions used in these methods all suffer from poor thermal stability at high temperatures of ABS resin, resulting in color deterioration of the molded product due to thermal deterioration during molding, and it is difficult to improve heat resistance. requires mixing a large amount of polycarbonate. In addition, when ABS resin is mixed with a large amount of polycarbonate, the moldability is poor because polycarbonate has high melt viscosity characteristics.
Further, there were problems such as the resin composition being expensive. The present invention improves these drawbacks, and the resin composition of the present invention has excellent thermal stability when molded at high temperatures compared to conventional resin compositions made of ABS resin and polycarbonate. The purpose of the present invention is to develop a well-balanced resin composition in which the obtained molded product does not deteriorate in color tone and has excellent moldability, impact resistance, and heat resistance. The resin composition of the present invention is particularly characterized by the addition of component (B), in which the α-methylstyrene monomer and vinyl cyanide monomer of component (B) used in the present invention are combined. The copolymer obtained by polymerization is produced by adding vinyl cyanide monomer to the polymerization system from the initial stage of polymerization, and in addition, during the substantial polymerization period, unreacted cyanide monomers in the polymerization system are removed. It is common to complete the polymerization by maintaining the composition ratio of the number of moles of the vinyl monomer and the total number of moles of the α-methylstyrene monomer and the vinyl monomer copolymerizable with these within a certain range. As a polymer, it is an important element that has excellent thermal stability against high temperatures. The resin composition containing component (B) of the present invention has sufficient thermal stability even when molded at high temperatures. It has a beautiful surface without black spots caused by discoloration, and is also characterized by excellent moldability, impact resistance, and heat resistance. The composition of the present invention consists of monomers consisting of 50 to 80% by weight of aromatic vinyl monomers, 15 to 35% by weight of vinyl cyanide monomers, and 0 to 30% by weight of vinyl monomers copolymerizable with these monomers. 10 to 40 parts by weight of a graft copolymer (component (A)) obtained by copolymerizing 20 to 70 parts by weight of the mixture in the presence of 30 to 80 parts by weight of diene synthetic rubber, and 60 to 40 parts by weight of α-methylstyrene monomer. 80% by weight, 15-30% by weight of vinyl cyanide monomer, and 0-25% by weight of vinyl monomer copolymerizable with these. Vinyl cyanide monomer is added to the polymerization system from the initial stage of polymerization, and during the actual polymerization period, the composition ratio of unreacted monomers in the polymerization system is α- to the number of moles of vinyl cyanide monomer. 60 to 90 parts by weight of a copolymer (component (B)) obtained by polymerizing the methylstyrene monomer and the copolymerizable vinyl monomer while maintaining the total number of moles at 1.3 to 3 times. This is a thermoplastic resin composition characterized by comprising 60 to 90 parts by weight of an ABS resin mixed with 10 to 40 parts by weight of polycarbonate (component (C)). The present invention will be explained in more detail below. First, the aromatic vinyl monomers used in producing the graft copolymer of component (A) include styrene (hereinafter abbreviated as SM), α-methylstyrene (hereinafter abbreviated as α-MSM), and vinyltoluene. , t-butylstyrene, halogen-substituted styrene, and mixtures thereof, with styrene and mixtures thereof being particularly preferred. Next, vinyl cyanide monomers include acrylonitrile (hereinafter abbreviated as AN), methacrylonitrile, α-chloroacrylonitrile, etc.
Especially preferred is AN. Specific examples of vinyl monomers copolymerizable with aromatic vinyl monomers and vinyl cyanide monomers include various known vinyl monomers such as methacrylic esters, acrylic esters, methacrylic acid, and acrylic acid. It is one or more selected from the following. Examples of diene-based synthetic rubbers include polymers of conjugated diene compounds such as butadiene and isoprene alone or with copolymerizable vinyl monomers, and polybutadiene is particularly preferred. In addition, the graft copolymer of component (A) is produced by mixing 30 to 80 parts by weight of diene synthetic rubber with 20 to 20 to 80 parts by weight of a monomer mixture such as aromatic vinyl or vinyl cyanide in the proportions described above.
70 parts by weight was graft-polymerized by a known method. Next, in producing the copolymer B, the composition ratio of unreacted monomers in the polymerization system is such that the composition ratio of the unreacted monomers in the polymerization system is equal to that of the α-methylstyrene monomer and the copolymerizable vinyl monomer. It is important to complete the polymerization by maintaining the total number of moles of the monomers at 1.3 to 3 times, particularly preferably 1.7 to 2.5 times, the number of moles of the vinyl cyanide monomer. If the number of moles exceeds three times the unreacted vinyl cyanide monomer, it will be difficult to obtain a polymer with a high molecular weight, and the impact resistance of the resin composition will deteriorate, and the polymerization rate will slow down significantly, resulting in a high yield. It becomes very difficult to obtain polymers at such low temperatures. On the other hand, if the number of moles is less than 1.3 times the amount of unreacted vinyl cyanide monomer, the color tone of the obtained polymer will be significantly deteriorated and the heat resistance will also be reduced. One monomer used in the copolymer of component (B) is α-MSM. Examples of vinyl cyanide monomers include AN, methacrylonitrile, and α-chloroacrylonitrile, with AN being particularly preferred. Specific examples of monomers copolymerizable with α-methylstyrene monomer and vinyl cyanide monomer include acenaphthylene, fumaronitrile, maleimide, N-substituted maleimide, methacrylic acid ester, acrylic acid ester, and methacrylic acid. , acrylic acid and aromatic vinyl monomers other than α-methylstyrene, such as vinyltoluene, t-butylstyrene, halogen-substituted styrene, and mixtures thereof. It is something. Next, component (C) polycarbonate is a polycarbonate derived from 4,4'-dihydroxydiarylalkane or 4,4'dihydroxy-3,5,3',5'-tetrahalogenodiphenylalkane, and is particularly preferably It is a polycarbonate derived from 4,4'-dihydroxydiphenylpropane as a main component. In the present invention, the above-mentioned graft copolymer as component (A), α-methylstyrene-vinyl cyanide copolymer as component (B), and polycarbonate as component (C) can be mixed by a known conventional method, e.g. Mixing can also be carried out using a single or twin screw extruder, a vented extruder, a mixing roll, a kneader, or the like. In addition, when melt-mixing is carried out at a high temperature, it is necessary to sufficiently remove moisture; if moisture is present, the polycarbonate will be hydrolyzed by the moisture, and the mechanical properties of the resin composition will be significantly deteriorated. The resin composition produced as described above may contain known fillers, stabilizers, flame retardants, pigments,
A lubricant, an antistatic agent, glass fiber, etc. can be added. EXAMPLES The present invention will be specifically explained below using Examples, but these are not intended to limit the scope of the present invention. Note that all parts and percentages described in this specification are expressed on a weight basis. Examples 1 to 3 and Comparative Example 1 Production of graft copolymer of component (A) 286 parts of polybutadiene latex (polybutadiene solid concentration 35%, average particle diameter 350 mμ; gel content 87%), 187 parts water, potassium fatty acid 1 part of ferrous sulfate, 0.004 part of ferrous sulfate, 0.01 part of tetrasodium ethylenediaminetetraacetate, and 0.2 part of sodium formaldehyde sulfoxylate were charged into a polymerization vessel, and t-dodecyl mercaptan was added while stirring at a temperature of 50°C.
A mixture of 18 parts of AN and 42 parts of SM in which 0.36 parts of dicumyl peroxide was dissolved was added in portions over 3 hours. After the completion of the partial addition, the temperature was heated to 65°C and polymerized for an additional hour to reduce the polybutadiene content.
A graft polymer of 62.5% was obtained. Production of copolymer of component (B) In a polymerization vessel, 70 parts of α-MSM, 5 parts of SM, AM15
20 parts of sodium dodecylbenzenesulfonate
% aqueous solution, 0.05 part of potassium chloride, 0.5 part of t-dodecyl mercaptan and 213 parts of water.
After raising the temperature to ℃, add 1% potassium persulfate aqueous solution.
6.7 parts were added to start polymerization. Further, 3.3 parts of the same aqueous solution was added 6 hours later. The polymerization rate one hour after the start of polymerization was 12.3%. From this point on, 10 parts of AN was added to the polymerization system over 6 hours using a metering pump. In order to observe changes in polymerization rate and composition of unreacted monomers over time, small amounts of the emulsion were sampled from the polymerization vessel. Polymerization was stopped in 10 hours to obtain a copolymer latex. The final polymerization rate is 96.8%.
It was hot. The polymer emulsion sampled during the process was analyzed by gas chromatography. The results are shown in Table 1.

[Table] 20 parts of the graft polymer latex of component (A) obtained as above and the copolymer latex of component (B)
80 parts were mixed so that the solid content of the mixed latex was 12.5% polybutadiene, and the mixture was coagulated, separated, and dried to obtain ABS resin powder. The ABS resin powder thus obtained and polycarbonate (C) component (manufactured by Teijin Chemicals, trade name Panlite K-1300W) were mixed in various proportions and extruded using a vented extruder to pelletize. It was injection molded and its physical properties were measured. For comparison, in the production of the copolymer latex of component (B), AN was not added and α-
The same procedure was followed except that 70 parts of MSM, 5 parts of SM, and 25 parts of AN were added. These conditions and results are shown in Table 2.

[Table] Examples 4 to 6 The same operation as in Example 1 was carried out except that 60 parts of α-MSM, 13 parts of AN, and 15 parts of methyl tacrylate were placed in a polymerization vessel and 12 parts of AN was added. A copolymer latex was obtained. 70 parts of this copolymer latex of component (B) was mixed with 30 parts of the graft copolymer latex of component (A) obtained in Example 1, so that the solid content of the mixed latex was 18.75%. The same procedure as in Example 1 was carried out except that the mixture was added to the following. These conditions and results are shown in Table 3.

[Table] In the Examples of the present invention, physical properties were measured by the following methods. (1) Heat distortion temperature ASTM method D648-56 (18.6Kg/cm ² ) (2) Izotsu impact strength ASTM method D256-56 (1/4 inch, temperature 20℃) (3) MFI (flowability test) ASTM method D-1238 (Temperature: 250°C, Load: 5Kg) (4) Molded product coloring test A tensile test piece injection molded at a temperature of 290°C was visually observed.

Claims (1)

[Scope of Claims] 1. Monomers consisting of 50 to 80% by weight of aromatic vinyl monomers, 15 to 35% by weight of vinyl cyanide monomers, and 0 to 30% by weight of vinyl monomers copolymerizable with these monomers. 10 to 40 parts by weight of a graft copolymer (component (A)) obtained by copolymerizing 20 to 70 parts by weight of a mixture of 20 to 70 parts by weight of a diene synthetic rubber in the presence of 30 to 80 parts by weight, and 60 parts by weight of α-methylstyrene monomer. ~80% by weight, 15-30% by weight of vinyl cyanide monomer, and 0-25% by weight of vinyl monomer copolymerizable with these. In this process, vinyl cyanide monomer is added to the polymerization system from the initial stage of polymerization, and during the actual polymerization period, the composition ratio of unreacted monomers in the polymerization system is α relative to the number of moles of vinyl cyanide monomer. - A copolymer obtained by polymerizing the methylstyrene monomer and the copolymerizable vinyl monomer while maintaining the total number of moles at 1.3 to 3 times (component (B)) 60 to 90% by weight 60 to 90 parts by weight of ABS resin mixed with 10 to 40 parts by weight of polycarbonate (component (C)).