JPS6314740B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention has a high heat distortion temperature and a high thermal decomposition temperature,
The present invention also relates to a thermoplastic resin composition having excellent impact resistance. Many studies have been conducted to improve the heat resistance of vinyl polymers. For example, it is known that copolymers made by copolymerizing maleic anhydride with vinyl monomers such as styrene have a high heat distortion temperature. However, this copolymer has a low thermal decomposition temperature (Kobunshi Ronshu, Vol. 32, Vol. 6).
(No. 342, published in 1975), it has the disadvantage of poor thermal stability during molding. In addition, a copolymer with a vinyl monomer using N-substituted alkylmaleimide instead of maleic anhydride has a high heat deformation temperature and a high thermal decomposition temperature (Kobunshi Journal,
Vol. 36, No. 7, p. 447, published in 1979), has excellent thermal stability during molding, but has poor mechanical properties, typified by impact resistance (LE Colemanet al, J.
Polymer Sci, Volume 38, Page 241, published in 1959)
Therefore, various attempts have been made to improve the mechanical properties by blending other polymers. For example, U.S. Patent No. 3,642,949 proposes a composition in which an N-substituted alkylmaleimide copolymer is blended with a graft copolymer based on a rubber-like polymer. There is a problem that the temperature is still insufficient, and when the amount of graft copolymer blended is reduced to satisfy the heat distortion temperature, the impact resistance is significantly reduced. Therefore, the present inventors conducted extensive studies with the aim of obtaining a thermoplastic material with excellent heat resistance, represented by heat distortion temperature and pyrolysis temperature, and mechanical properties, represented by impact resistance, in a well-balanced manner. The inventors have discovered that the above object can be effectively achieved by blending a copolymer using a -substituted phenylmaleimide with a specific graft copolymer, and have thus arrived at the present invention. That is, the present invention involves polymerizing a monomer mixture consisting of (A) 45 to 70% by weight of N-substituted phenylmaleimide and 55 to 30% by weight of at least one other vinyl monomer copolymerizable therewith. Copolymer 20-95
parts by weight and (B) 80 to 20% by weight of a monomer mixture consisting of at least one type of styrene and another vinyl monomer copolymerizable therewith in the presence of 20 to 80% by weight of the rubbery polymer. Graft copolymer formed by polymerization
The object of the present invention is to provide a thermoplastic resin composition containing 80 to 5 parts by weight. The above N-substituted phenylmaleimide copolymer (A)
has a high heat distortion temperature and pyrolysis temperature, but
By itself, it is brittle and has poor impact resistance. Graft copolymers (B) such as acrylonitrile-butadiene-styrene copolymers have excellent impact resistance, but are insufficient in heat resistance as typified by heat distortion temperature. However, the composition of the present invention consisting of an N-substituted phenylmaleimide copolymer (A) and a graft copolymer (B) is composed of a conventional N-substituted alkylmaleimide copolymer and a graft copolymer. Compared to other compositions, it exhibits significantly improved impact resistance while maintaining high heat distortion and thermal decomposition temperatures. The N-substituted phenylmaleimide constituting the copolymer (A) of the present invention is a monomer represented by the following formula (). However, X ₁ and X ₂ in the formula are each independently hydrogen,
Indicates halogen, aryl group, aralkyl group, alkyl group, cycloalkyl group, etc. If X ₁ and X ₂ have the above-mentioned 5-membered ring imide structure, substituents having any chemical structure can be applied to the present invention, but usually in the above formula ()
Those in which X ₁ and X ₂ are hydrogen, bromine, chlorine, methyl group, ethyl group, phenyl group, or substituted phenyl group are generally used. In addition, other vinyl monomer mixtures copolymerizable with N-substituted phenylmaleimide include styrene,
Aromatic vinyl monomers represented by α-methylstyrene, indene, acenaphthylene, etc., (meth)acrylic acid ester monomers represented by methyl methacrylate, methyl acrylate, etc., and acrylonitrile, methacrylonitrile, etc. Typical examples include vinyl cyanide monomers, and two or more of these can be used in combination. Particularly preferred among these vinyl monomers are styrene, α-methylstyrene, methyl methacrylate, and acrylonitrile. The amount of copolymerized N-substituted phenylmaleimide in the copolymer (A) is 45 to 70% by weight, and 45% by weight.
If it is less than 70% by weight, the heat distortion temperature of the resulting copolymer and thus the composition will be lowered, and if it exceeds 70% by weight, the impact resistance of the composition will be lowered, which is not preferable. The method for producing the copolymer (A) is not particularly limited, and it can be produced by conventional emulsion polymerization, suspension polymerization, solution polymerization, bulk polymerization, or bulk-suspension polymerization. The graft copolymer (B) used in the present invention is a monomer mixture consisting of styrene and at least one other vinyl monomer copolymerizable with it in the presence of a rubbery polymer. It is made by
The other vinyl monomers mentioned here include aromatic vinyl monomers, (meth)acrylic acid ester monomers, vinyl cyanide monomers, and the like. Particularly preferred monomers for grafting onto the rubbery polymer to improve or control the impact strength of the composition are styrene, α-methylstyrene, methyl methacrylate, acrylonitrile, and N-phenylmaleimide. . Examples of rubbery polymers include diene rubbers such as polybutadiene rubber, acrylonitrile-butadiene copolymer rubber (NBR), and styrene-butadiene copolymer rubber (SBR), and acrylic rubbers such as polybutyl acrylate and polypropyl acrylate. , ethylene-propylene-diene rubber (EPDM), etc. can be used. however,
The ratio of the rubbery polymer to the vinyl monomer mixture in the graft copolymer (B) is important; mass mixture 80-20% by weight, especially
It is necessary to polymerize 70-30% by weight. If the proportion of the rubbery polymer is less than 20% by weight, the resulting composition will not have sufficient impact resistance;
Exceeding this is not preferred because it not only reduces the mechanical strength of the composition obtained, but also gives undesirable results in appearance such as gloss. Note that these graft copolymers (B) are produced by known polymerization methods such as emulsion polymerization, bulk polymerization, and bulk-suspension polymerization. The resin composition of the present invention can be obtained by blending the above-mentioned copolymer (A) and graft copolymer (B), and the blending ratio is such that (A) is 20 to 95 parts by weight, especially 30 to 90 parts by weight, 80 to 5 parts by weight of (B), particularly 70 to 10 parts by weight (total 100 parts by weight). If the amount of copolymer (A) is less than 20 parts by weight, only a composition with an extremely low heat distortion temperature will be obtained, and if it exceeds 95 parts by weight, the impact resistance of the composition will decrease, which is not preferable. Further, by further blending another polymer (C) with the thermoplastic resin composition of the present invention, various properties can be exhibited. Examples of such polymers (C) include (co)polymers of vinyl monomers such as styrene, α-methylstyrene, methyl methacrylate, and acrylonitrile, and amide-based monomers such as nylon. Examples include polyester polymers such as polyethylene terephthalate and polybutylene terephthalate, among them styrene-acrylonitrile copolymer, styrene-α-methylstyrene-acrylonitrile copolymer, and styrene-methacrylic acid. Methyl-acrylonitrile copolymer, methyl methacrylate-acrylonitrile copolymer,
Styrene-methyl methacrylate copolymer and methyl methacrylate homopolymer can be preferably used. There are no particular restrictions on the method of blending the above copolymer (A) and graft copolymer (B). For example, powdered polymers may be mixed in advance or not mixed before being fed to an extruder in a desired ratio and melted. Methods such as mixing are adopted. In addition, the thermoplastic resin composition of the present invention may be added with antioxidants such as ordinary hindered phenol antioxidants, phosphorus antioxidants, and sulfur antioxidants to improve thermal stability, or may be used as a lubricant. It is also possible to further improve the fluidity by adding . Depending on the purpose, fiber reinforcing agents such as glass fibers, inorganic fillers, colorants, and pigments can also be blended.
Furthermore, flame retardation can be achieved by mixing general halogenated organic compound flame retardants such as tetrabromobisphenol A, decabromobiphenyl ether, and brominated polycarbonate with antimony oxide into the resin composition of the present invention. be. As explained above, the thermoplastic resin composition of the present invention has an excellent balance of heat resistance represented by heat distortion temperature and thermal decomposition temperature, and mechanical properties represented by impact resistance. It is expected that it will be applied to a variety of applications. The present invention will be further explained below using reference examples and examples. In addition, the heat distortion temperature in the reference examples and examples is ASTM D-648-56, and the Izod impact value is
Measured according to ASTM D-256-56Method A. The pyrolysis temperature was determined by increasing the temperature at a rate of 10°C/min under a nitrogen stream using a thermogravimetric analyzer, measuring the change in weight of the sample, and determining the pyrolysis temperature as the temperature at which the sample weight decreased by 3%. . Also, the number of parts is parts by weight, %
represents weight %. Reference example 1 (1) N-substituted phenylmaleimide copolymer (A),
Preparation of N-alkylmaleimide copolymer (A') Among the raw material monomers shown in Table 1, 100 parts of a vinyl monomer mixture was dissolved in 100 parts of methyl ethyl ketone along with 0.3 parts of benzoyl peroxide initiator. The mixture was charged into a reaction tank and thoroughly stirred while maintaining the temperature inside the tank at 75°C. Polymerization is carried out by dropping a predetermined amount of N-substituted phenylmaleimide or N-alkylmaleimide dissolved in 100 parts of methyl ethyl ketone into the solution at a predetermined rate.
N-substituted phenylmaleimide copolymers (A) and N-alkylmaleimide copolymers (A') having various compositions were obtained. When the contents of N-substituted phenylmaleimide and N-alkylmaleimide were determined from morphological analysis, a copolymer having the copolymer composition shown in Table 1 was obtained. (2) Preparation of maleic anhydride copolymer (A″) 100 parts of vinyl monomer was mixed with 0.3 parts of benzoyl peroxide initiator and 100 parts of methyl ethyl ketone.
Dissolve the liquid into a reaction tank and set the temperature inside the tank to 75%.
Sufficient stirring was performed while maintaining the temperature at °C. Polymerization was carried out while a predetermined amount of maleic anhydride dissolved in 100 parts of methyl ethyl ketone was added dropwise at a predetermined rate to prepare maleic anhydride-based copolymers (A'') having two types of composition.Elemental analysis The maleic anhydride content was determined from the following, and the copolymers shown in Table 1 were obtained.

[Table] (3) Preparation of graft copolymer (B) Styrene and a mixture of other vinyl monomers copolymerizable with it were polymerized in the presence of various rubber-like polymers, and the mixture shown in Table 2 was prepared. Ten types of graft copolymers (B) with the following compositions were prepared. In Table 2, PBD is polybutadiene rubber, SBR is styrene-butadiene copolymer rubber consisting of 25% styrene and 75% butadiene, and EPDM is element value 23 and Mooney viscosity.
60 ethylene/propylene/5-ethylidene-2
-Represents norbornene terpolymer rubber (ethylene/propylene = 68.5/31.5 molar ratio).

[Table] (4) Preparation of polymer (C) Four types of polymer (C) having the compositions shown in Table 3 were prepared.

[Table] Example 1 (A) N-substituted phenylmaleimide copolymers (A-1 to A-12) prepared in Reference Example 1, (A') N-
Alkylmaleimide copolymer (A′-1, A′-
2), (A″) Maleic anhydride copolymer (A″-1,
A″-2), (B) graft copolymer (B-1 to B-
10) and (C) polymers (C-1 to C-4) were blended in the proportions shown in Table 4, and after melt extrusion using an extruder, the physical properties of the test pieces obtained by injection molding were measured. The measurement results of heat distortion temperature, thermal decomposition temperature and Izod impact strength are shown in Table 4 together with the blending ratio.

【table】

[Table] As is clear from Table 4, the composition of the present invention (No.
Nos. 2 to 3, 6, 8, and 10 to 14) are excellent in thermal deformation temperature, thermal decomposition temperature, and impact strength in a well-balanced manner. In contrast, (A) the N-substituted phenylmaleimide content of the N-substituted phenylmaleimide copolymer, (B) the rubbery polymer content of the graft copolymer, or (A) and (B) If any or both of the mixing ratios are off (No. 1, 4-5, 7, 9, 15-
22) have insufficient impact strength even if the heat distortion temperature is high (No. 1, 4-5, 7, 9, 15-17),
Even if the impact strength is high, the heat distortion temperature may be insufficient (Nos. 18 to 22). In addition, when (A') N-alkylmaleimide copolymer is used (No. 23,
24) has a low heat distortion temperature (No. 23), and as the heat distortion temperature increases, the impact strength decreases (No. 24). Also,
(A″) When using maleic anhydride copolymer (No. 25, 26), both heat distortion temperature and impact strength are high and well-balanced, but thermal decomposition temperature is low and thermal stability during molding is low. is inferior.

Claims (1)

[Claims] 1 (A) A copolymer obtained by polymerizing a monomer mixture consisting of 45 to 70% by weight of N-substituted phenylmaleimide and 55 to 30% by weight of at least one other vinyl monomer copolymerizable with this. 20-95 parts by weight of polymer and
(B) Polymerizing 80 to 20% by weight of a monomer mixture consisting of styrene and at least one other vinyl monomer copolymerizable with it in the presence of 20 to 80% by weight of a rubbery polymer. A thermoplastic resin composition containing 80 to 5 parts by weight of a graft copolymer.