JPH0422178B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a rubber-modified styrenic resin composition that has excellent appearance, impact strength, and heat resistance. Conventionally, ABS resin has been used as a resin with high heat resistance, high gloss, and high impact strength, and is used in home appliances, audio equipment, automobile parts, etc. recently,
As the cost reduction trend in these applications increases, there is a strong tendency to substitute cheaper rubber-modified styrene resins. When replacing rubber-modified styrenic resin with the physical properties of ABS resin (heat resistance, appearance characteristics,
impact strength). Although the balance between appearance characteristics and impact strength of conventional rubber-modified styrenic resins has been improved by controlling the average particle size of the rubber-like elastomer,
It has not yet reached the point where it fully satisfies market demands.
Furthermore, even if unreacted monomers, oligomers, etc. are removed as much as possible, the heat resistance is limited to a heating deformation temperature of 83 to 84°C, and the market requirement of 87 to 90°C cannot be achieved. The object of the present invention is to provide a heat-resistant rubber-modified styrenic resin composition that incorporates α-methylstyrene and has improved the balance of appearance characteristics and impact strength to a level that can replace ABS resin. In order to accomplish this task, the present inventors have developed α
- In a rubber-modified styrenic resin composition incorporating methylstyrene, the particle size distribution of dispersed particles made of a rubber-like elastic body and the combination of additives were studied in detail, and the particle size distribution was appropriately adjusted and It has been discovered that if an appropriate amount of the seed additive is added, an excellent heat-resistant rubber-modified styrenic resin composition with an improved balance of the above-mentioned appearance characteristics and impact strength can be obtained. That is, in a rubber-modified styrenic resin composition containing a rubbery elastomer as dispersed particles, (A) the continuous phase consists of styrene and α-methylstyrene, and the α-methylstyrene content is 10 to 40% by weight. Yes (B) The particle size of the dispersed particles () of the dispersed phase is
25% or more and less than 70% of the dispersed particles are less than 7500 Å, and () the particle diameter of the dispersed particles is 7500 Å or more 21500
25% or more of the dispersed particles are less than Å ()
18% or less of the dispersed particles have a particle size of 21,500 Å or more, and the particle size of the dispersed particles has a continuous distribution, and (C) based on 100 parts by weight of the rubber-modified styrenic resin composition. organic polysiloxane
This is a rubber-modified styrenic resin composition with excellent appearance, impact strength, and heat resistance, characterized by containing 0.02 parts by weight or more and 0.2 parts by weight or less. In the present invention, if the content of α-methylstyrene in the continuous phase is less than 10% by weight, heat resistance will decrease. If it exceeds 40% by weight, productivity will decrease and the molecular weight will not increase and impact strength will not improve even if the method of the present invention is used. Dispersed particles with a particle diameter of less than 7500 Å are 70
If it exceeds 25%, the impact strength will decrease, and if it is less than 25%, the appearance characteristics will decrease. Also, the particle size is 7500Å or more
If the dispersed particles of less than 21500 Å are less than 25%, the impact strength decreases. If the proportion of dispersed particles with a particle size of 21,500 Å or more exceeds 18%, the appearance characteristics will deteriorate, and the effect of additives will decrease, resulting in a decrease in impact strength. If the amount of organic polysiloxane is less than 0.02 parts by weight, no impact strength reinforcing effect can be obtained. In addition, if the amount of organic polysiloxane exceeds 0.2 parts by weight, no further impact strength reinforcement effect will be observed, leading to a decrease in rigidity.
It causes the sweating phenomenon during molding, and
This is not preferable because it increases costs. In addition, the particle size of the dispersed particles in the present invention refers to the diameter of the dispersed particles in the photo taken with a transmission electron microscope taken at a magnification of 10,000 using an ultra-thin section method of the resin.
This was determined by measuring the number of 2000 particles. At the time of measurement, the particles are classified as shown in Table 1, and the proportion of dispersed particles having a particle size within a certain range is determined by the following formula. Ratio (%) of dispersed particles=100NiDi/ΣNiDi Ni is the number of dispersed particles having particle diameter Di.

【table】

Claims (1)

[Scope of Claims] 1 (A) A styrene-α-methylstyrene copolymer or a mixture of this and polystyrene,
The continuous phase is a polymer or polymer mixture with an α-methylstyrene content of 10 to 40% by weight, and (B)() 25% or more of particles with a particle size of less than 7500 Å70
Less than % () 25% or more of particles with a particle size of 7500 Å or more and less than 21500 Å () 18% or less of particles with a particle size of 21500 Å or more, dispersed particles of rubber-like elastic material with a continuous particle size distribution A rubber-modified styrenic resin composition containing 100 parts by weight of a rubber-modified styrenic resin composition as a phase and 0.02 to 0.2 parts by weight of an organic polysiloxane.