JPH075819B2 - Resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a thermoplastic resin having high impact resistance.

<Prior Art> ABS resin is a typical thermoplastic resin obtained by graft-copolymerizing an aromatic vinyl monomer and a vinyl cyan monomer with a rubber-like polymer, and these resins have mechanical and thermal properties. Widely used in balanced resin.

Of these mechanical properties, impact resistance is particularly important, and in order to improve this impact resistance since ancient times, for example, (1) rubber particle size, (2) rubber gel content, (3) graft ratio ,
(4) Various studies have been made on additives and the like.

However, as the market demand for the thermoplastic resin has increased, it has become impossible to deal with it by simply changing these characteristics. Therefore, for example, in Japanese Patent Publication No. 58-1683, gel content of 60% or more, 70% of rubber particles
% Rubber and gel content 70% in the range 1730-4400Å
Below, a method for improving impact resistance by blending two kinds of rubbers having different particle diameters, that is, a rubber having a particle diameter of 4400Å or more, is proposed. In addition, Japanese Patent Publication No. 59-49937 has a particle size of 500.
It has been proposed to improve impact resistance with a composition in which rubber particles having a small particle diameter of up to 2000 Å are continuously dispersed in a ring shape or a donut shape.

<Problems to be Solved by the Invention> The resin produced by the method described in Japanese Patent Publication No. 58-1683 has a certain effect in improving the impact resistance.
As shown in the figure, since the butadiene-based polymer latex 5 having a particle diameter of 1730 to 4400Å is mixed with the large-sized butadiene-based polymer latex 6 having a particle diameter of 4400Å or more, the impact resistance is improved to some extent, Not enough. (7 is a grafted styrene-acrylonitrile copolymer.) Furthermore, the resin composition described in JP-B-59-49939 is the third one.
As shown in the figure, the inclusion of the hard resin 10 such as styrene-acrylonitrile copolymer inside the small particle diameter rubber 9 connected in a ring shape or a donut shape increases the apparent rubber particle diameter and the rubber efficiency, and the impact resistance is improved. However, since the size and amount of the resin inside the ring-shaped or donut-shaped rubber is not appropriate, there is a problem that a high degree of impact resistance cannot be obtained.

The present inventors have made a rubber (A) consisting of an aromatic vinyl monomer and a vinyl cyan monomer present inside each rubber-like polymer particle to increase the apparent rubber particle diameter. Further, the inventors have found that the impact resistance of the resin composition can be enhanced by allowing the copolymer (a) to have a particle size of a certain size or more, and the present invention has been completed.

<Means for Solving Problems> Therefore, the present invention has the following configuration. That is, (a) a graft copolymer obtained by copolymerizing a rubber-like polymer with one or more aromatic vinyl monomers and one or more vinyl cyan monomers, and (b) an aromatic vinyl monomer. In a thermoplastic resin composition comprising a copolymer obtained by copolymerizing at least one type of monomer and at least one type of vinylcyan monomer, inside and outside of rubber-like polymer particles forming a graft copolymer. Exists in the copolymer (a) of the aromatic vinyl monomer and the vinyl cyan monomer derived from (a), and the copolymer (a) in the rubbery polymer particles is present. 10% or more of particles having a particle diameter of 0.1 μm or more, and the content of the copolymer (a) present inside the rubber-like polymer particles is such that the rubber-like polymer and the copolymer present inside ( 20-50 for the total amount of b)
The resin composition is wt%.

Impact resistance is significantly improved by the resin composition of the present invention. That is, the resin composition contains 10% or more, preferably 10 to 60%, of the copolymer (a) having a particle diameter of 0.1 μm or more present inside the rubbery polymer. This is
When it is less than 10%, the deformation behavior of the rubber-like polymer becomes similar to that when the copolymer (a) does not exist inside the rubber-like polymer when an impact is applied from the outside, and the desired resistance is obtained. It is considered that the impact resistance is not improved.

Further, in the resin composition of the present invention, the content of the copolymer (a) present inside the rubber-like polymer is 20 to the total amount of the rubber-like polymer and the copolymer (a) present inside. 50wt%,
It is preferably contained at 25 to 40 wt%. If it is less than 20 wt%, the apparent particle size of the rubber-like polymer does not become so large,
When it is more than 50 wt%, the rubbery polymer does not lose its properties as a rubber and becomes brittle, and in any case, improvement in impact resistance cannot be expected.

The rubber content of the graft copolymer derived from (a) in the present invention is preferably from 15 to 70 wt%, and when it is less than 15 wt%, the desired impact resistance cannot be obtained and when it is more than 70 wt%. However, the dispersibility at the time of compounding becomes worse, which is not preferable.

In addition, the mixing ratio of the remainder of the graft copolymer derived from (a) and the aromatic vinyl monomer and vinyl cyan monomer of the copolymer derived from (b) is 60 to 90 wt% / 40 to 10 wt%
When the content of aromatic monomer is less than 60 wt%, the final product has poor moldability and color tone, and 90 wt%
If it is larger, the desired impact resistance cannot be obtained, which is not preferable.

The blending ratio of the graft copolymer derived from (a) and the copolymer derived from (b) is (a) :( b) = 15 to
100 wt%: 85 to 0 wt%, and the rubber content after compounding is
It is preferably 12 to 40 wt%, particularly preferably 15 to 25 wt%.
% Is desirable.

A compounding ratio and a rubber content outside this range are not preferable because no remarkable improvement in impact resistance is observed.

The rubber-like polymer used to obtain the graft copolymer used in the present invention is preferably a polybutadiene latex having an average particle size of 0.15 to 1.20μ, preferably 0.2 to 0.5μ. When using rubber particles with a diameter exceeding this range,
The effect of the present invention cannot be sufficiently obtained from the viewpoint of the performance of the final product.

Examples of the aromatic vinyl monomer used in the present invention include:
Examples of styrene, α-methylstyrene, p-vinyltoluene and the like, and vinyl cyanide monomer include acrylonitrile and methacrylonitrile.

The resin composition of the present invention will be described with reference to FIG. 1, which is a schematic view. In the rubber-like polymer particles 1, there are 2 copolymer particles (a) of an aromatic vinyl monomer and a vinyl cyan monomer. Of the 2 above, 10% or more of particles having a particle diameter of 0.1 μm or more are contained. The rubber-like polymer particles 1 are surrounded by a copolymer 3 of an aromatic vinyl monomer and a vinyl cyan monomer grafted on the outside. Non-grafted aromatic vinyl monomer and vinyl cyan monomer copolymer derived from (a) and aromatic vinyl monomer and vinyl cyan monomer copolymer derived from (b) 4
Is the matrix.

Here, it is compared with FIG. 2, which is a model diagram of the rubber form described in Japanese Patent Publication No. 58-1683. 5 is a large particle size butadiene-based polymer having a particle size of 4400Å or more, 6 is a butadiene-based polymer present in a particle size range of 1730 to 4400Å, 7 is a vinyl aromatic compound and a vinyl cyanide compound grafted to the butadiene-based polymer. And 8 is a copolymer of a vinyl aromatic compound and a vinyl cyan compound. Fig. 3 shows the Japanese Patent Publication Sho 59-
It is a model diagram of the rubber form of 49937, where 9 is a particle size of 500-
2000Å small rubber particles, 10 is a styrene-acrylonitrile copolymer surrounded by rubber particles, 11 is a grafted styrene-acrylonitrile copolymer, and 12 is a styrene-acrylonitrile copolymer.

The rubbers 1, 5, 6, and 9 are equivalent to each other except that they have different characteristics.

3, 7 and 11 are grafted acrylonitrile-styrene copolymers and are equivalent.

4,8,12 are acrylonitrile as a matrix-
It is a styrene copolymer and is equivalent.

2 and 10 are acrylonitrile-styrene copolymers existing inside the rubber particles, but 10 shows that several rubber particles surround the acrylonitrile-styrene copolymer, and it seems as if the copolymer exists inside the rubber. On the other hand, 2 in the resin composition of the present invention is a copolymer of acrylonitrile and styrene inside one rubber particle, and the presence of this 2 significantly improves the impact resistance of the resin. Is done.

The graft copolymer (a) in the present invention is obtained, for example, as follows. First, as the first step, 10 to 70% of the total amount of the monomer mixture of the aromatic vinyl monomer and the vinyl cyan monomer in the rubber-like polymer latex in the polymerization vessel, the chain transfer agent, and the 10-hour half-life. After adding the thermal polymerization catalyst of 55 to 80 ° C all at once, heat. After that, of the monomers added in the first step, when the amount corresponding to 0.1 to 3 times the solid content of the rubber-like polymer was polymerized, the balance of the chain transfer agent of the monomer mixture was set as the second step. Then, a redox polymerization catalyst and a reducing agent are charged, and the polymerization is completed when the main content of the total monomer mixture reaches 95 to 99%.

Further, the copolymer (b) is prepared by a commonly used polymerization method, for example, 60 to 90 parts by weight of an aromatic vinyl monomer and 10 to 40 parts by weight of a vinyl cyan monomer are emulsified, suspended, lumpy or ,
It can be obtained by polymerizing a combination of these.

<Examples> The present invention will be specifically described with reference to Examples.

Example 1 15 equipped with a temperature control device, a stirring device, and each chemical liquid charging device
Polybutadiene latex with a solid content of 50 wt% (gel content 75%, average particle size 0.4μ)
m) 5000 g and deionized water 1000 g were charged and the temperature was raised to 70 ° C. At 55 ° C during the temperature rise, a mixture of azobisisobutyronitrile (AI BN) 7.5g styrene 900g acrylonitrile 350g t-dodecyl mercaptan 10g and a higher fatty acid potassium aqueous solution (18wt% aqueous solution) were added all at once in the polymerization vessel. To do. The temperature inside the polymerization tank is 70
The starting point is when the temperature reaches ℃.

One hour after the initiation of polymerization, a reducing agent / auxiliary mixture solution 714 g (7%
Aqueous solution) and the following were added over 1 hour.

Styrene 900 g Acrylonitrile 350 g t-Dodecyl mercaptan 10 g Higher fatty acid potassium liquid (18% aqueous solution) 333 g Cumene hydroperoxide 7.5 g After the addition was completed, the reaction was continued for 30 minutes and then cooled to complete the reaction.

90-95 ℃ after adding 50g of antioxidant to the above latex
It was dropped into a dilute sulfuric acid aqueous solution whose temperature had been adjusted to solidify. Then, a graft copolymer was obtained through washing, dehydration and drying steps.

From the electron micrograph of the graft copolymer thus obtained, the particle size of the acrylonitrile-styrene copolymer present inside the polybutadiene particles, the ratio of 0.1μ or more is 14%, the content of the copolymer is 34wt %Met.

Comparative Example 1 Addition before the start of polymerization.

Instead of azobisisobutyronitrile, 1,1-bis-
Obtained by the same polymerization method as in Example 1 except that 3,3,5-trimethylcyclohexane was used.

From the electron micrograph of the graft copolymer thus obtained, the particle size of the acrylonitrile-styrene copolymer present inside the polybutadiene particles was 0.1% or more, the ratio was 5%, and the content of the copolymer was 30 wt. %Met.

Comparative Example 2 The same polymerization apparatus as in Example 1 was charged with 5000 g of polybutadiene latex having a solid content of 50 wt% and 1000 g of deionized water, and the temperature was raised to 70 ° C.

Then a mixture of 1800 g of styrene, 700 g of acrylonitrile, 12.5 g of t-dodecyl mercaptan was added over 3.5 hours. 15 minutes after the addition of the above mixture was started, a mixture of 333 g of higher fatty acid potassium liquid (18% aqueous solution) and 10.0 g of cumene hydroperoxide was added over 4.5 hours. After the addition was completed, stirring was continued for 30 minutes and cooled to complete the polymerization.

The above latex was subjected to the same post-treatment as in Example 1 to obtain a graft copolymer.

From the electron micrograph of the graft copolymer thus obtained, the particle size of the acrylonitrile-styrene copolymer present inside the polybutadiene particles was 0.1% or more, the ratio was 0%, and the content of the copolymer was 15 wt. %Met.

Example 2 The graft copolymer obtained in Example 1 comprises 72 parts by weight of styrene and 28 parts by weight of acrylonitrile, and has an intrinsic viscosity [η] of 30 ° C. measured in a methyl ethyl ketone solvent at 30 ° C.
= 0.55 dl / g styrene-acrylonitrile copolymer and polybutadiene content of 18 wt%
S resin was obtained.

Various properties of these resins were examined by the following methods.

Flowability: 220 ° C according to JIS-K7210, MFR with a load of 10 kg Impact resistance: 1/2 ″ according to ASTMD-256, Izod impact strength (23 ° C notch) Stiffness: Bending elastic modulus according to ASTMD-790 Particle size and rubber Internal resin content: By the usual osmic acid dyeing method,
The prepared sample was magnified 20,000 times with an electron microscope and the particle size was determined from a photograph taken. Further, from this photograph, the content of the styrene-acrylonitrile copolymer inside the rubber-like polymer was calculated from the cross-sectional area and determined.

Comparative Example 3 The graft copolymer obtained in Comparative Example 1 and the acrylonitrile-styrene copolymer used in Example 2 were blended to obtain an ABS resin with a polybutadiene content of 18%.

Comparative Example 4 The graft copolymer obtained in Comparative Example 2 and the acrylonitrile-styrene copolymer used in Example 2 were blended to obtain an ABS resin having a polybutadiene content of 18%.

Example 3 An ABS resin was obtained in the same manner as in Example 2 except that the polybutadiene content was 25 wt%.

Comparative Example 5 An ABS resin was obtained in the same manner as in Comparative Example 3 except that the polybutadiene content was 25 wt%.

Comparative Example 6 An ABS resin was obtained in the same manner as in Comparative Example 4 except that the polybutadiene content was adjusted to 25 wt%.

Example 4 Except that the polybutadiene content was adjusted to 12%,
An ABS resin was obtained in the same manner as in Example 2.

Comparative Example 7 Except that the polybutadiene content was adjusted to 12%,
An ABS resin was obtained in the same manner as in Comparative Example 3.

Comparative Example 8 Except that the polybutadiene content was 12%,
An ABS resin was obtained in the same manner as in Comparative Example 4.

<Effects of the Invention> In the present invention, a copolymer composed of an aromatic vinyl monomer and a vinyl cyan monomer is present inside each rubber-like polymer particle to increase the apparent rubber particle diameter. In addition, by allowing the copolymer to have a particle size of at least a certain size, a resin composition having extremely high impact resistance can be obtained even when only one kind of rubber, which is easy to manufacture, is used. Especially.

[Brief description of drawings]

FIG. 1 is a model diagram of a resin composition of the present invention, and FIGS. 2 and 3 are model diagrams of a conventional resin composition. 1, 5, 6, 9 ... Rubber 3, 7, 11 ... Grafted acrylonitrile-styrene copolymer 4, 8, 12 ... Acrylonitrile-styrene copolymer as matrix 2, 10 ... Inside rubber particles Acrylonitrile present-
Styrene copolymer

Claims (1)

[Claims] 1. A graft copolymer obtained by copolymerizing (a) a rubber-like polymer with at least one aromatic vinyl monomer and at least one vinylcyan monomer, and (b) an aroma. A thermoplastic resin composition comprising a copolymer obtained by copolymerizing one or more group vinyl monomers with one or more vinyl cyan monomers, comprising a rubber-like polymer particle forming a graft copolymer. A copolymer (a) derived from (a) derived from an aromatic vinyl monomer and a vinyl cyan monomer is present inside and outside, and a copolymer (a) present inside the rubber-like polymer particles ( The content of the copolymer (a) present in the rubber-like polymer particles is 10% or more, and the content of the copolymer (a) present in the rubber-like polymer and the inside thereof is 0.1 μm or more. 20 to 50 based on the total amount of polymer (a)
A resin composition characterized by being wt%.