JPS6231019B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel thermoplastic resin composition that has pearlescent luster and excellent physical properties such as elongation and Izot impact strength. Various types of thermoplastic resin compositions having pearlescent luster have been known. As a means of imparting particularly excellent pearlescent luster,
Combinations of styrene resins such as polystyrene and acrylic resins such as polymethyl methacrylate are known, but in these combinations, the compatibility between each resin is very poor and lamination is easy, and this lamination Parts may peel off on the surface, especially due to elongation, impact strength,
The drawback is that the practical impact strength is low. As a method to solve this drawback, a method has been proposed in which a styrene-butadiene block copolymer having a linear structure is blended into the above-mentioned two-component composition (Japanese Patent Publication No. 49-4553, Japanese Patent Application Laid-open No. 49-1651). reference). In such three-component compositions, the range in which pearlescent luster can be obtained and impact strength can be exhibited is relatively narrow, and it is difficult to control the composition. The present invention relates to a novel blended composition that has excellent pearlescent luster and can maintain practical impact strength, particularly elongation and impact strength over a wide range. That is, the present invention provides acrylic acid ester resins from 10 to
General formula (A-B) _x Y (where A is an aromatic vinyl polymer block, B is a conjugated diene polymer block, and Y is 90 parts by weight and a conjugated diene content of 40 wt% or less)
is an atom or atoms derived from the polyfunctional treatment agent used to form the radial polymer, x represents the number of functional groups in the polyfunctional treatment agent, and is an integer of at least 3. . ) is a pearlescent resin composition comprising a blend with 90 to 10 parts by weight of a radially branched block copolymer represented by: The present invention will be explained in detail below. The acrylic ester resin referred to in the present invention is
A polymer or copolymer containing at least 40% by weight of methacrylic acid ester. Specifically, it is a copolymer of polymethyl methacrylate (PMMA), styrene-methyl methacrylate copolymer resin (PMS), or α-methylstyrene-methyl methacrylate copolymer resin having a light refractive index of 1.54 or less. Further, in the radially branched block copolymer represented by the general formula (A-B) _x Y according to the present invention, the aromatic vinyl polymer A may include, for example, styrene,
It is a polymer block formed of a vinyl aromatic compound such as α-methylstyrene or vinyltoluene, and the conjugated diene polymer block B is formed of a conjugated diene compound such as butadiene or isoprene. This is a polymer block made of Atom(s) Y may also be a polyfunctional treatment agent used in the formation of radial polymers, such as polyepoxides, polyisocyanates, polyaldehydes, polyketones, tetraallyltin, or tin compounds such as stannic fluoride. x is an integer of at least 3, preferably 4 or more. Further, the proportion of the aromatic vinyl polymer block A and the conjugated diene polymer block B can vary over a wide range, but preferably the content of the conjugated diene polymer B is 40 to 10 wt% and the aromatic vinyl polymer block is 40 to 10 wt%. 60～
A resin-like branched block copolymer with a low rubber content of 90 wt% is preferred. Such a branched block copolymer has excellent physical properties such as strength and processability, as well as particularly excellent transparency, and its specific production method is described in Japanese Patent Publication No. 48-4106 and Japanese Patent Publication No. 48-4106. It is described in detail in Publication No. 49-36957. The composition of the present invention is a two-component system consisting of an acrylic ester fat and a branched block copolymer.
These two materials melt together in a desired ratio, exhibiting pearlescent luster over a wide range, and at the same time exhibiting excellent physical properties such as elongation and practical impact strength such as Izot impact strength. In a particularly preferred embodiment of the present invention, rather than kneading the two, the mixture is simply dry blended and injection molded, and in this case, the blending ratio is 20 to 80% of the acrylic ester resin.
% by weight, branched block copolymer 80-20% by weight
is within the range of In addition, when making a pellet form by kneading both, the acrylic ester resin
30-70% by weight, 70-30% branched block copolymer
It is preferable that the amount is within the range of % by weight, and if it is outside the above range, the pearlescent effect will be weak. The composition of the present invention exhibits pearlescent luster without using a colorant, but if necessary, one or both resins may be blended with a colorant such as a suitable dye or pigment in advance. Good too. The present invention will be explained in more detail below with reference to Examples. Example 1 and Comparative Example 1 Styrene-methyl methacrylate copolymer resin (PMS) or polymethyl containing 30, 45, 60, and 100 wt% of uncolored methyl methacrylate (MMA) as acrylic acid ester resin, respectively Methacrylate copolymer resin (PMMA),
Unpigmented as a radially branched block copolymer,
After dry blending a styrene-butadiene block copolymer with three or more branches (product name: K-Resin, manufactured by Philips Corporation) with a butadiene content of 25 wt% at the ratio shown in Table 1, Pour into a 3 oz screw in-line mold,
A plate-shaped product with a thickness of 3 mm, a length of 50 mm, and a width of 40 mm was injection molded. The presence or absence of pearlescent luster at this time was as shown in Table 1. As a comparative example, a case in which a linear styrene-butadiene block copolymer (trade name: Tuffrene, manufactured by Asahi Kasei Industries, Ltd.) with a butadiene content of 60 wt% was used in place of K-resin was also used.
Shown in the table.

【table】

[Table] Example 2 and Comparative Example 2 Polymethyl methacrylate resin (PMMA)
(Kyowa Gas Chemical Co., Ltd., trade name Parapet G) and the same branched block copolymer (K
-Resin) were dry blended at different blending ratios, kneaded into pellets using an extruder, and then injection molded into test pieces (JIS K6872) using an injection molding machine. It is shown in Table 2. As a comparative example, a branched block copolymer (K
-Resin) was replaced with the same linear styrene-butadiene block copolymer (Tuffprene) used in the comparative example in Example 1 and polystyrene (trade name: Estyrene G-15, manufactured by Nippon Steel Chemical Co., Ltd.). After dry blending in a three-component system and kneading into pellets using an extruder, test pieces were produced in the same manner using an injection molding machine, and the physical property values of each were measured. The results are also shown in Table 2.

[Table] As is clear from the results in Table 2 above, the physical properties of the composition of the present invention are equivalent to or even better than those of the comparative example in which the rubber content is approximately constant. In particular, the point that the elongation (%) is significantly improved and at the same time the Izotsu impact value is almost constant is that
The selection range of blended compositions is wide, and blending management is easier. The composition of the present invention is suitable for molded products expected to have a decorative effect, such as toys, cosmetic containers, musical instruments, and other uses, and can be molded by injection molding, extrusion molding, compression molding, or other molding methods. It can be easily molded.

Claims (1)

[Claims] 1 General formula (A-B) of 20 to 80 parts by weight of an acrylic ester resin containing 40% by weight or more of methacrylic ester and a conjugated diene content of 10 to 40% by weight
xY (where A is the aromatic vinyl polymer block, B is the conjugated diene polymer block, and Y is the atom(s) derived from the polyfunctional processing agent used to form the radial polymer; x represents the number of functional groups in the multifunctional treatment agent, and is an integer of at least 3. Resin composition.