JPH0619011B2 - Thermoplastic resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermoplastic resin composition, and more particularly to a thermoplastic resin composition containing polyphenylene ether and a rubber-modified polystyrene resin or polystyrene and rubber.

Polyphenylene ether is known as a thermoplastic resin excellent in heat resistance, mechanical and electrical properties. or,
It is well known that a composition obtained by blending this resin with various resins, especially polystyrene resin, is used as a general molding material by improving the processability of polyphenylene ether. (For example, U.S. Patents 3,383,435 and 4,1
No. 23,602, JP-B-43-17812) Further, rubber is added or mixed with a rubber-modified polystyrene resin for the purpose of improving impact resistance, but the size of the particles of the elastic phase dispersed in the composition. Greatly affects the impact strength. For example, Japanese Examined Patent Publication No. 51-28659 describes that if the average particle size of the dispersed elastic phase particles is kept at 0.5 to 2 .mu.m, a significantly improved impact resistance is exhibited.

It is said that the impact resistance of the polystyrene resin is preferably such that the size of the elastic particles dispersed in the resin is in the range of 2 to 5 μm. (For example, Encyclopedia of Polymer Science and Technology, Volume 13, 3
However, even if the average particle size is within these ranges, it does not necessarily give a molded product of satisfactory quality. Therefore, the present invention has been reached as a result of examining the relationship between the distribution state of the particle size of the elastic phase and the quality. In particular, the particle size distribution of the elastic phase is important in order to obtain a well-formed product that has good workability and is excellent in mechanical strength including impact resistance, thermal properties, surface gloss, etc. I found that.

That is, the present invention contains polyphenylene ether and (a) polystyrene resin and rubber, (b) rubber-modified polystyrene resin or (c) the mixture of (a) and (b), and the particles of the elastic phase are larger than 3.5 μ. It has a weight average particle size and the particle size is
The ratio of particles of 1.5μ to 4μ is 40% by weight or more (however, the number of particles of 0.5 to 4μ forming the elastic phase is less than 80% of the number of all rubber particles), and the particle size is 5μ. Provided is a thermoplastic resin composition having an elastic phase of dispersed particles having a particle size distribution such that the proportion of larger particles is 25% by weight or less.

The composition is generally composed of two phases, the discontinuous phase being elastic particles and the continuous phase being a matrix of polyphenylene ether and styrene resin.

The size and distribution of particles can be controlled by the method of making the composition. For example, the polystyrene resin and the rubber can be finely dispersed by mechanically mixing the polyphenylene ether resin. Alternatively, as a preferred method, a rubber-modified polystyrene resin and a polyphenylene ether resin can be blended. Rubber-modified polystyrene is produced by polymerizing styrene in which rubber is dissolved by a well-known method. A dispersed elastic phase of grafted and crosslinked rubber particles is formed in the polystyrene matrix. The particle size distribution of the elastic body phase can be controlled by any method.

However, rubber-modified polystyrene having various particle sizes may be mixed with each other. Further, rubber can be further added to match the above particle size distribution.

The size of the particles of the elastic phase is, for example, an ultrathin section is prepared from a pellet or a molded article of the composition, and after dyeing with osmium tetroxide, a 2200 times electron micrograph is taken to count the diameter and the number of particles, The weight average particle diameter was calculated by the following formula.

The weight percentage was similarly obtained for the particle size distribution. Grace
It is necessary to count at least 2,000 particles, preferably 5,000 or more, to know the exact distribution.

For a description of the relationship between conventional particle size distribution and quality, see Japanese Patent Laid-Open No.
-65249 and Japanese Patent Publication No. 51-28659, both of which are described in terms of particle number distribution. However, when the relationship between the particle size distribution and the quality was examined in detail, it was found that the relationship between the particle number distribution and the quality cannot be accurately grasped.
For example, the weight of one elastic particle having a particle size of 3μ is
Equivalent to a weight of 27,000 particles with a particle size of 0.1μ. When comparing the quality at the same rubber content in the composition, it is difficult to relate by the number average particle size and the distribution of the number, it is desirable to use the weight average particle size and the weight percentage, and it is actually I found that they are often related.

The polyphenylene ether used in the present invention has the general formula (In the formula, the oxygen atom of the repeating unit is connected to the benzene nucleus of the next adjacent unit, n represents a positive integer of at least 50, and Q represents hydrogen, halogen, a hydrocarbon group, a halogen atom and a phenyl nucleus. A monovalent substituent selected from the group consisting of haloalkoxy groups having at least 2 carbon atoms between). Above all, those of the above general formula in which each Q is an alkyl group having 1 to 4 carbon atoms are particularly preferable. As a specific example, poly (2,
6-dimethyl-1,4-phenylene) ether, poly (2,6-dimethyl-1,4-phenylene) ether,
Poly (2-methyl-6-ethyl-1,4-phenylene)
Ether, poly (2-methyl-6-propyl-1,4-
Phenylene) ether, poly- (2,6-dipropyl-
1,4-phenylene) ether and poly (2-ethyl-6-propyl-1,4-phenylene) ether are mentioned. Particularly preferred is poly (2,6-dimethyl-
1,4-phenylene) ether, which is compatible with polystyrene in all proportions and forms a single-phase composition.

Polystyrene used in the present invention is generally a vinyl aromatic monomer such as the one represented by the general formula (In the formula, R is hydrogen, a lower alkyl group (for example, having 1 carbon atom)
~ 4 alkyl group) or halogen, Z represents hydrogen, vinyl group, halogen or lower alkyl group, and p represents 0 or an integer of 1 to 5). Of at least 25% by weight. Examples of polystyrene resins include polystyrene, polychlorostyrene, homopolymers such as poly-α-methylstyrene, styrene-containing copolymers such as styrene-acrylonitrile copolymers, copolymers of ethylvinylbenzene and divinylbenzene, styrene- Includes acrylonitrile-methylstyrene terpolymer and the like.

Especially preferred is homopolystyrene.

Rubber as used in the present invention means natural and synthetic polymeric materials that are elastic at room temperature, for example 20-25 ° C. Examples of rubbers include natural rubbers and polymerized diene rubbers such as polybutadiene and polyisoprene, and copolymers of diene and vinyl monomers such as vinyl aromatic monomers such as styrene. Examples of suitable rubbers or rubbery polymers are natural crepe rubbers, SBR type synthetic rubbers obtained by emulsion polymerization of butadiene and styrene,
G prepared from butadiene and acrylonitrile
Methods using RN type synthetic rubbers and heterogeneous catalyst systems such as trialkylaluminums and titanium halides raise synthetic rubbers prepared for example from butadiene, butadiene-styrene or isoprene.

Examples of synthetic rubbers that can be used for producing the composition of the present invention include polychlorobutadiene, polyisobutylene, copolymers of isobutylene and butadiene or isoprene, polyisoprene, copolymers of ethylene and propylene, ethylene. , Copolymers of propylene and dienes, thiochol rubber, polysulfide rubber, acrylic rubber, polyurethane rubber, diene and various monomers (for example, unsaturated alkyl esters such as methyl methacrylate, methyl isopropyl ketone, etc. Copolymers with unsaturated ketones or vinyl heterocycles such as vinylpyridi),
Examples include polyether rubber and epichlorohydrin rubber. Particularly preferred rubbers are polybutadiene and rubbery copolymers of butadiene and styrene.

The rubber-modified polystyrene resin is a generic term for compounds containing a two-phase system in which rubber is dispersed in a polystyrene resin matrix in the form of discrete particles. The particles can be formed by mechanically mixing rubber and polystyrene resin. It is also possible to polymerize styrene in the presence of rubber and disperse the grafted elastic body phase in the polystyrene resin. In this case, the elastic phase particles also contain the occluded styrene polymer.

The composition of the present invention is a mixture of polyphenylene ether and polystyrene resin, but the ratio thereof can be arbitrarily selected. Generally, the ratio of polystyrene to polyphenylene ether is preferably 20 to 80% by weight on the basis of excluding rubber.

In the composition of the present invention, the rubber content can be widely varied. However, in order to obtain a composition having excellent properties such as impact strength, tensile strength, surface appearance, and flow, the rubber content is preferably 1 to 15% by weight with respect to the total weight of the composition, and 1.5 to 10% by weight. % Is more preferable.

The elastic phase particles of the composition of the present invention have a weight average particle size of 3.5.
more than 3.5 μm, preferably more than 3.5 μm and less than 4 μm, and the proportion of particles of 1.5 μm to 4 μm is 40% by weight or more (however, the number of particles of 0.5 to 4 μm forming the elastic phase is equal to that of all rubber particles). If the particle size distribution is such that the ratio of particles larger than 5μ is 25% by weight or less, there is no particular limitation on the method for forming the composition. A preferred method is to mix the rubber-modified polystyrene such that the proportion of particles larger than 5μ is 25% by weight or less and the polyphenylene ether using conventional mixing methods, and the composition thus formed is extruded, It can be molded into a desired shape by a method such as heat molding.

Other additives in the composition of the invention, such as plasticizers, pigments,
Flame retardants, reinforcing agents (eg glass fibers or filaments), stabilizers and the like can be added.

Further, other polymers such as polyamide, polyolefin, polystyrene and the like can be added to the composition.

The invention is illustrated by the following examples, but unless otherwise stated all compositions are polyphenylene ether, styrene resin and rubber or a mixture of high impact polystyrene and other components at about 240 ° C to 280 ° C. The filament was extruded from a twin-screw extruder at a temperature in the range of ° C, cooled, and cut into pellets.

The pellets were put into an injection molding machine and each test piece was prepared and evaluated.

Example 1 and Comparative Examples 1 and 2 3 kg of a composition was obtained by mixing in the weight ratios shown in Table 1.

The composition was extruded with a twin-screw extruder at 260 ° C., cooled, and then cut into pellets. Particle size distribution of elastic phase in pellets,
The weight average particle size remained unchanged.

The physical properties of these two compositions are shown in Table 1.

As can be seen from the table, even if the particles have the same weight average particle size, those having a large weight ratio of 5 μm or more have a poor gloss.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication C08L 51:04) (72) Inventor Takao Ninomiya 2-40 Tsukahara, Takatsuki, Osaka Sumitomo Chemical Co., Ltd. In-house (72) Inventor Satoshi Ebiko 2-40 Tsukahara, Takatsuki City, Osaka Prefecture Sumitomo Chemical Co., Ltd. (56) References JP-A-49-99649 (JP, A) JP-A-57-174344 (JP, A) )

Claims (3)

[Claims] 1. An elastic phase particle containing polyphenylene ether and (a) polystyrene resin and rubber, (b) rubber-modified polystyrene resin, or (c) a mixture of (a) and (b) above, and having an elastic phase particle of 3.5. The weight average particle size is larger than μ, and the ratio of particles having a particle size of 1.5 to 4 μ is 40% by weight or more (however, the number of particles of 0.5 to 4 μ forming the elastic phase is equal to the number of all rubber particles). Is less than 80%), and has a particle size distribution in which the proportion of particles having a particle size of greater than 5 μ is 25% by weight or less. 2. The thermoplastic resin composition according to claim 1, wherein the weight average particle diameter of the particles of the elastic phase is more than 3.5 μ and not more than 4 μ. 3. The thermoplastic resin composition according to claim 1 or 2, wherein the proportion of the rubber component in the composition is 1% by weight to 15% by weight.