JPH0125334B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a thermoplastic resin composition having excellent transparency, heat resistance, and impact resistance. In recent years, polyglutarimide, which has been proposed as a new imide polymer with excellent heat resistance, for example in Japanese Patent Application Laid-open No. 52-63989, has a high heat distortion temperature, but has poor mechanical properties such as impact strength. In reality, its use as a molding material is quite limited due to its inferiority. Various methods have been studied to improve the above-mentioned drawbacks of polyglutarimide. (1) Acrylonitrile/butadiene/styrene-based (ABS)
method using methyl methacrylate/butadiene/styrene (MBS) copolymer or alkyl acrylate rubber (JP-A-Show)
52-63989), (2) A method of using polycarbonate in combination with a multistage polymer based on butadiene rubber or alkyl acrylate rubber (Japanese Patent Laid-Open Publication No. 52-63989).
55-80459) and (3) a method of using a combination of a multistage polymer based on butadiene rubber and a multistage polymer based on alkyl acrylate rubber (Japanese Patent Application Laid-open No. 152740/1983). ing. However, the impact strength obtained by method (1) above is still insufficient, and it is necessary to mix a large amount of modifier to obtain higher impact strength.
Heat resistance has to be sacrificed. Also, (2) and (3) above
Although the impact strength can be improved to some extent by this method, the improvement effect is small and the heat resistance of the composition is rather deteriorated. Furthermore, the compositions produced by these methods have a problem of being extremely poor in transparency and therefore cannot be applied to applications that particularly require transparency. On the other hand, transparent impact-resistant resins include methyl methacrylate/butadiene/styrene resins (MBS
Rubber-modified acrylic resins such as BACKGROUND ART (BACKGROUND ART) are known and are used for various purposes, but they have the fatal drawback of having a low heat distortion temperature and poor heat resistance. Therefore, the present inventors conducted intensive studies with the aim of obtaining a thermoplastic molding material with an excellent balance of transparency, heat resistance, and impact resistance, and found that methyl methacrylate and acrylonitrile were By mixing a graft copolymer obtained by polymerizing a monomer mixture containing as an essential component and polyglutarimide in such a range that the refractive index of both satisfies specific conditions, the above purpose can be fully satisfied. It was discovered that a thermoplastic resin can be obtained, and the present invention was achieved. That is, the present invention comprises (A) polyglutarimide and
(B) In the presence of (a) 10 to 80% by weight of a diene-based rubbery polymer, (b) 90 to 20% by weight of a vinyl monomer mixture containing methyl methacrylate and acrylonitrile as essential components is polymerized. and the difference between the refractive index of (a) the diene rubber-like polymer and (b) the refractive index of the vinyl copolymer consisting only of the vinyl monomer mixture is substantially 0.02.
A blend with the following graft copolymer, wherein the difference between the refractive index of (A) polyglutarimide and the refractive index of (B) the graft copolymer is substantially 0.02 or less, and the blending ratio is (A) 10~90 parts by weight and (B) 90~
10 parts by weight (total 100 parts by weight). It has been known for a long time that a transparent resin composition can be obtained by reducing the difference in refractive index of each resin component in a resin composition in which two or more resin components are mixed. It is also known that in impact-resistant resins, the smaller the difference in refractive index between the base rubbery polymer and the grafted polymer, the more transparent the impact-resistant resin can be obtained. Therefore, the above-mentioned Japanese Patent Application Laid-Open No. 52-63989
In the composition of the publication in which MBS resin is blended with polyglutarimide, if the refractive indexes of the two match, a resin composition with good transparency can be obtained. Even if the heat resistance is satisfied, the impact resistance is still insufficient. However, according to the present invention, acrylonitrile is an essential component along with methyl methacrylate as a graft component of the graft copolymer (B), and (B)
In the graft copolymer, the refractive index difference between (a) the rubbery polymer and (b) the graft component, and the refractive index difference between (A) polyglutarimide and (B) the graft copolymer, respectively.
By setting it to 0.02 or less, a resin composition with excellent transparency and heat resistance and extremely improved impact resistance can be obtained. This effect of the present invention is achieved by (B) graft copolymer having acrylonitrile as an essential component, (A)
This is due to the improved compatibility between polyglutarimide and the graft copolymer (B), which maximizes the heat resistance improvement effect of (A) and the mechanical property improvement effect of (B). Conceivable. The polyglutarimide (A) used in the present invention is a polymer or copolymer containing a cyclic imide unit represented by the following formula (). However, R ₁ , R ₂ and R ₃ in the formula each represent hydrogen or a substituted or unsubstituted alkyl group or aryl group having 1 to 20 carbon atoms. Any polyglutarimide having any chemical structure can be applied to the present invention as long as it contains the above-mentioned cyclic imide unit, but usually R ₁ and R ₂ in the above-mentioned cyclic imide unit are hydrogen or methyl groups. Generally used are those in which R ₃ is hydrogen, methyl group, ethyl group, propyl group, butyl group or phenyl group. The method for producing polyglutarimide is not particularly limited, but for example, polymethyl methacrylate described in JP-A-52-63989 is reacted with ammonia or a primary amine such as methylamine or ethylamine in an extruder. Methods that form glutarimide rings are useful. (B) Graft copolymer used in the present invention is obtained by polymerizing (b) a vinyl monomer mixture containing methyl methacrylate and acrylonitrile as essential components in the presence of (a) a diene rubber polymer. Although it is a graft copolymer, the absolute value of the difference between (a) the refractive index of the diene rubber-like polymer and (b) the refractive index of the copolymer itself formed by copolymerizing only the vinyl monomer mixture is Must be less than or equal to 0.02. A transparent graft copolymer (B) can be obtained by controlling the absolute value of this difference in refractive index to 0.02 or less. (a) The diene rubber-like polymers include polybutadiene rubber, styrene/butadiene copolymer rubber (SBR), and acrylonitrile/butadiene copolymer rubber (NBR).
etc. can be used. In addition, (b) the vinyl monomer mixture contains methyl methacrylate and acrylonitrile as essential components, and the refractive index of the copolymer made only of this vinyl monomer is higher than that of the rubber-like polymer (a). The composition is selected so that the refractive index is similar to that of the graft copolymer (B) and the refractive index of the polyglutarimide (A) is 0.02 or less. (b) Methyl methacrylate in the vinyl monomer mixture is an essential component for obtaining a transparent resin composition, and acrylonitrile is an essential component for obtaining a resin composition with high impact strength. (b) If the monomer mixture does not contain acrylonitrile, a resin composition with high impact strength cannot be obtained. (b) In addition to methyl methacrylate and acrylonitrile, the vinyl monomer mixture can also contain other vinyl monomers such as styrene, α-methylstyrene, maleic anhydride, etc. By selecting these compositions, Adjustment of the refractive index can also be performed. (B) In the polymerization of graft copolymer, (a) diene-based rubbery polymer
(b) vinyl monomer mixture in the presence of 10 to 80% by weight
It is necessary to polymerize 90-20% by weight. (a) If the diene-based rubbery polymer is less than 10% by weight, the resulting composition will not only have insufficient impact resistance, but also have a significantly lower heat distortion temperature, and if it exceeds 80% by weight, the resulting resin composition This is not preferred because the impact resistance of the product is extremely poor. When mixing the above (A) polyglutarimide and (B) graft copolymer, the absolute value of the difference between the refractive index of (A) polyglutarimide and the refractive index of (B) graft copolymer must be 0.02 or less. Must be. The resin composition obtained when this condition is satisfied has transparency. The blending ratio of (A) polyglutarimide and (B) graft copolymer is 10 to 90 parts by weight of (A), 90 to 10 parts by weight of (B), and 100 parts by weight of (A) + (B). It can be arbitrarily selected according to the desired heat distortion temperature, impact strength and melt fluidity within the range of
~80 parts by weight, 60-20 parts by weight of (B) (total 100 parts by weight)
In this case, a particularly desirable resin composition can be obtained. By further mixing a transparent vinyl (co)polymer into the resin composition of the present invention, the heat distortion temperature, impact strength, and melt fluidity of the resin composition are further improved while maintaining transparency. can be done. Examples of these (co)polymers include methyl methacrylate/acrylonitrile copolymer, styrene/acrylonitrile copolymer, styrene/methyl methacrylate/acrylonitrile copolymer,
Examples include α-methylstyrene/styrene/acrylonitrile copolymer, α-methylstyrene/methyl methacrylate/acrylonitrile copolymer, and styrene/maleic anhydride copolymer, but the refractive index of these (co)polymers The difference in refractive index between the composition and the composition of the present invention needs to be 0.02 or less. In addition, the thermoplastic resin composition of the present invention may be added with ordinary antioxidants such as hindered phenol antioxidants, phosphorus antioxidants, and sulfur antioxidants to improve thermal stability, or may be added with a lubricant. can be added to further improve melt fluidity. Further, reinforcing agents, fillers, retardant agents, coloring agents, etc. can also be blended within a range that does not impair transparency. There are no particular restrictions on the method of blending the thermoplastic resin composition of the present invention, and for example, (A) polyglutarimide and
(B) A method is adopted in which the graft copolymers are mixed in advance or are supplied to an extruder at a desired ratio without being mixed, and then melt-mixed. As explained above, the thermoplastic resin composition of the present invention has good transparency, heat resistance represented by heat distortion temperature, mechanical properties represented by impact resistance, and fluidity during melt molding. It has an excellent balance of properties, and is expected to be applied to a variety of applications that take advantage of these properties. The present invention will be further explained below using reference examples and examples. In this example, the heat distortion temperature is
ASTM D-648-56, Izotsu impact strength is
Measured according to ASTM D-256-56 Method A. The refractive index was measured at 20°C using an Atsube refractometer. The light transmittance was measured by press-molding a sheet with a thickness of 1 mm and using a spectrophotometer at a light wavelength of 580 mμ. Hereinafter, parts refer to parts by weight, and % refers to % by weight. Reference Example 1 Preparation of (A) polyglutarimide, (B) graft copolymer, and (C) vinyl copolymer (A) polyglutarimide Pellets of polymethyl methacrylate were extruded with ammonia, methylamine, or ethylamine. While degassing the generated gas from the exhaust port attached to the extruder, the resin temperature is increased to 280℃.
Three types of polyglutarimides shown in Table 1 were prepared by extrusion at .degree.

[Table] (B) Graft copolymer A monomer mixture was polymerized in the presence of various diene-based rubbery polymers in the proportions shown in Table 2 to produce graft copolymers (B-1) to (B-5). ) was prepared. In Table 2, PBD is polybutadiene rubber (refractive index 1.516), SBR is copolymer rubber (refractive index 1.535) consisting of 25% by weight of styrene and 75% by weight of butadiene, and NBR is 30% by weight of acrylonitrile and 70% by weight of butadiene. It is a copolymer rubber (refractive index 1.515) consisting of % by weight.

[Table] (C) Vinyl copolymers Three types of vinyl copolymers (C) having the compositions shown in Table 3 were prepared.

[Table] Example 1 (A) Polyglutarimide prepared in Reference Example 1, (B)
The graft copolymer and (C) copolymer were mixed in the proportions shown in Table 4, and the heat distortion temperature, Izod impact strength, and light transmittance of test pieces molded by injection molding were measured. These results are shown in Table 4.

[Table] As is clear from Table 4, the conditions of the present invention are met.
A resin composition obtained by mixing the graft copolymer (B) and the polyglutarimide (A) shows good transparency, has a high heat distortion temperature, and has excellent impact resistance. (No.
1-5) Furthermore, by mixing a copolymer with adjusted refractive index such as styrene/methyl methacrylate/acrylonitrile copolymer as a third resin component, impact strength can be improved while maintaining good transparency. It is possible to improve the balance of physical properties such as heat deformation temperature and heat deformation temperature. (Nos. 6 to 9) On the other hand, even if the graft copolymer (B) that does not meet the conditions of the present invention is mixed, the transparency may be impaired or the impact strength may be low, resulting in a desired resin composition. I can't. (No. 10 to 13) Even if the graft copolymer (B) satisfies the conditions of the present invention, if the difference in refractive index of the polyglutarimide (A) is greater than 0.002, the resulting resin composition will be opaque. become. (No.14)

Claims (1)

[Claims] 1 (A) polyglutarimide and (B) a vinyl monomer mixture containing (b) methyl methacrylate and acrylonitrile as essential components in the presence of (a) 10 to 80% by weight of a diene rubber polymer (90 to 90%) 20% by weight of the vinyl copolymer, and the difference in refractive index between (a) the diene rubber-like polymer and (b) the vinyl copolymer consisting only of the vinyl monomer mixture is substantially 0.02 or less, the difference between the refractive index of (A) polyglutarimide and the refractive index of (B) the graft copolymer is substantially 0.02 or less, and The ratio is (A) 10 to 90 parts by weight and (B) 90 to 10 parts by weight (total
100 parts by weight).