JPS592300B2 - Impact resistant resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resin composition having good impact resistance and moldability.

More specifically, the intrinsic viscosity is 0.1 for ABS resin.
The present invention relates to an impact-resistant resin composition formed by mixing a low molecular weight styrene-acrylonitrile copolymer with a molecular weight of 0 or less. ABS resins represented by acrylonitrile-butadiene-styrene terpolymer are resins with well-balanced mechanical and thermal properties, but in order for these ABS resins to exhibit their original physical properties, (1) Rubber
It is necessary to have an appropriate graft structure that governs compatibility with the resin, (2) to have an appropriate average molecular weight and molecular weight distribution of the resin phase, and (3) to select appropriate additives. It can be said that by combining the above three requirements, an ABS resin that satisfies various uses has been created.

On the other hand, in the molding industry, there are more opportunities to produce large injection molded products, so the physical properties required of resins are becoming more stringent, and ABS resins with balanced moldability and mechanical properties are required. There is. However, in the current concept, moldability and mechanical properties of resins are contradictory properties, and the current situation is that in order to improve moldability, mechanical properties must be sacrificed to some extent.

That is, one way to improve the moldability of ABS resin is to lower the molecular weight of the styrene-acrylonitrile copolymer that constitutes the continuous phase of the resin, but the molecular weight parameter of the styrene-acrylonitrile copolymer Although moldability improves when the intrinsic viscosity is set to 0.43 or less, even if a rubber graft structure is considered, the rubber efficiency is poor and the result is a resin with poor impact resistance.

Therefore, in order to maintain the optimum impact resistance of ABS resin, the styrene-acrylonitrile copolymer phase must have an intrinsic viscosity of 0.45 or more, particularly a molecular weight of 0.05 or more, and this resin is a prerequisite. The optimal design of the resin has been achieved by examining the rubber graft structure and various additives. In view of this situation, the present inventors conducted intensive studies with the aim of obtaining an ABS resin with excellent balance between impact resistance and moldability. By mixing a specific amount of low molecular weight styrene-acrylonitrile copolymer,
The inventors have discovered that the impact resistance of ABS resin is improved and the moldability is improved, and the present invention has been achieved.

That is, the present invention has an intrinsic viscosity of 0.1 for ABS resin.
The present invention provides an impact-resistant resin composition comprising 0.1 to 10% by weight of the following low molecular weight styrene-acrylonitrile copolymer.

The ABS resin used in the present invention is made by graft polymerizing a styrene-acrylonitrile resin phase onto a diene rubber-like polymer such as polybutadiene, butadiene-acrylonitrile copolymer rubber, butadiene-styrene copolymer rubber, etc. The conventional emulsion polymerization method, suspension polymerization method, bulk-suspension polymerization method, graft blend method, etc. can be employed, and there are no particular restrictions on the structure of the rubber phase and graft phase of the ABS resin itself.

Note that the styrene-acrylonitrile resin phase of the ABS resin may contain a small proportion of other copolymerizable vinyl monomers such as methyl acrylate, methyl methacrylate, and α-methylstyrene. The higher the rubber content of these ABS resins, the greater the effect of blending the low molecular weight styrene-acrylonitrile copolymer, but usually the rubber content is 5 to 30.
% by weight can be used.

Regarding the composition of the styrene-acrylonitrile resin phase of ABS resin, the higher the acrylonitrile content, the greater the increase in impact strength due to the addition of a low molecular weight styrene-acrylonitrile copolymer, but usually the styrene/acrylonitrile weight ratio is 90/ A ratio of 10 to 60/40 is preferred.

The intrinsic viscosity of this styrene-acrylonitrile resin phase is preferably 0.43 or more in order to obtain higher impact strength. In addition, the intrinsic viscosity as used in the present invention refers to the polymer 1y
This figure shows [η] measured at 30°C for a solution prepared by dissolving 100cc of methyl ethyl ketone.

The intrinsic viscosity of the low molecular weight styrene-acrylonitrile copolymer compounded in the above ABS resin is 0.1 or less, particularly 0.1 or less.
If the intrinsic viscosity of the low molecular weight material is 0.1 or more, the impact resistance and moldability of the ABS resin cannot be improved. The amount of styrene-acrylonitrile copolymer added to ABS resin is 0.1 to 10
% by weight, especially 0.5 to 5.0% by weight, preferably 0.1
If it is less than % by weight, the effect of improving impact resistance and workability is small;
If it is 10% by weight or more, moldability is improved, but impact resistance is extremely reduced, and this is preferable because it exhibits the same tendency as impact resistance reduction when the intrinsic viscosity of the styrene-acrylonitrile resin phase of ABS resin is apparently reduced. do not have. The composition of the low molecular weight styrene-acrylonitrile copolymer has a styrene/acrylonitrile weight ratio of 90/10 to 60.
/40 is appropriate.

These low molecular weight substances are produced by radical polymerization and ionic polymerization such as emulsion polymerization, suspension polymerization, solution polymerization, and bulk polymerization methods. Preferably, a low molecular weight product obtained by hot bulk polymerization has a large effect of increasing impact resistance, and the polymerization conditions are arbitrarily selected depending on the combination of polymerization temperature and mercabutane. Mixing of the ABS resin and the low molecular weight styrene-acrylonitrile copolymer is accomplished using a commonly used powder mixer.

For example, a predetermined amount of the low molecular weight material according to the present invention may be added to ABS resin powder and styrene acrylonitrile copolymer beads, and the mixture may be kneaded using a pen shell mixer type mixer.

In the composition of the present invention obtained in this manner, the impact resistance of the ABS resin itself is further improved by mixing the low molecular weight styrene acrylonitrile copolymer, and furthermore, the apparent melt viscosity of the ABS resin is reduced and moldability is improved. It is in extremely good condition.

The reason for this effect is currently unknown, but it is likely that a low molecular weight styrene-acrylonitrile copolymer is added to the styrene-acrylonitrile resin phase of the ABS resin matrix and the grafted styrene-acrylonitrile resin phase on the rubber. By mixing, ABS
This is thought to be due to an increase in the affinity between the rubber phase of the resin and the resin phase, resulting in an increase in rubber efficiency. The effects of the present invention will be explained in further detail with reference to Examples below.

Example 1 A styrene-acrylonitrile copolymer (styrene/acrylonitrile-68.5/31.5) with an intrinsic viscosity of 0.69 obtained by a continuous bulk polymerization method was placed in methanol for 60 min.
The methanol-soluble content was extracted by boiling at ℃.

As a result, the methanol soluble content was 1.2%, and this soluble content was a low molecular weight styrene-acrylonitrile substance with an intrinsic viscosity of 0.027 and a pasty form at room temperature. The above-mentioned low-molecular-weight material was added to Toyorak T-100 (X), which is a commercially available ABS resin.
) (manufactured by Toray Industries, Inc.) was mixed with 1.0% by weight to form a test piece, and its impact strength and formability (220°C, 50k9/C with a Koka type flow tester manufactured by Shimadzu Corporation) were molded.
Table 1 shows the evaluation results of the apparent melt viscosity measured under d loading.

As is clear from the results in Table 1, the addition of a low molecular weight styrene-acrylonitrile copolymer improves the impact strength and moldability in a balanced manner. Example 2 Various low molecular weight styrene-acrylonitrile copolymers having the intrinsic viscosities shown in Table 2 were prepared by patch-type hot bulk polymerization.

Each low molecular weight styrene/'A (the weight ratio of acrylonitrile is 70/30 for each styrene in Table 2)
A low molecular weight acrylonitrile copolymer was added to the ABS resin (Toyorak TlOO) used in Example 1 in the amount shown in Table 3, and the impact resistance and melt viscosity were measured in the same manner as in Example 1. are shown in Table 3.

As is clear from the results in Table 3, when the intrinsic viscosity of the low molecular weight styrene-acrylonitrile copolymer is 0.1 or more, the effect of improving the impact resistance of the ABS resin is not recognized. Furthermore, if the amount of the low molecular weight substance added is 10% by weight or more, the melt flow characteristics (moldability) will be very good, but the impact strength will be significantly lowered, which is not preferable. Example 3 The following low molecular weight styrene-acrylonitrile copolymer was prepared by bulk thermal polymerization.

That is, 20 parts by weight of styrene, 80 parts by weight of acrylonitrile.
parts by weight and 1.5 parts by weight of normal octyl mercaptan were charged, and as the polymerization progressed at 150°C, only styrene was added to control the residual monomer composition during polymerization to be constant at 20/80 of styrene/acrylonitrile. The obtained low molecular weight styrene-acrylonitrile copolymer had an intrinsic viscosity of 0.082 and a brown color.

This low molecular weight material had a rubber content of 20% by weight, a styrene/acrylonitrile weight ratio of 68.5/31.5, and a styrene-acrylonitrile weight ratio of 68.5/31.5.
Table 4 shows the results of adding 1.0% by weight of the acrylonitrile resin phase to an ABS resin having an intrinsic viscosity of 0.62 and evaluating it in the same manner as in Example 1.

Claims (1)

[Claims] 1. A low molecular weight styrene-acrylonitrile copolymer with an intrinsic viscosity of 0.10 or less is added to ABS resin from 0.1 to 0.1.
An impact-resistant resin composition formed by mixing 10% by weight.