JPS61127338A - Plastic molded member - Google Patents

Abstract

PURPOSE:To offer a plastic molded material which is superior in heat resistance especially creep characteristics at a high temperature and suitable for a vibration insulation material, by constituting the plastic molded material with a first and second molded member parts made of a hard thermoplastic polymer and a third molded member part made of soft thermoplastic elastomer, with which silyl denatured EVA resin has compounded, and crosslinked. CONSTITUTION:Plastic molded member is constituted with a first and second molded member parts 1, 2 which are made of hard thermoplastic polymer, concentric and separated substantially from each other and a third molded member part 3 made of thermoplastic elastomer extended to a space between the first and second member parts and stuck to them. Then the third molded member part is made into an article obtained by making a resin composite obtained by mixing styrene series thermoplastic elastomer with ethylene vinyl acetate copolymer resin which is crosslinkable at normal temperatures and silyl denaturation at a weight ratio within a range of 40:60-95:5 crosslink. This molded member can be massproduced efficiently by performing simultaneous molding by making use of a double head injection molding machine.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a plastic molded article that is heat resistant and useful as a vibration damping material.

(Technical Background of the Invention) Conventionally, there has been a method to prevent the generation of vibrations or to remove O vibrations from the outside.
Various shapes of vibration isolating materials have been used for the purpose of alleviating shock waves, but in recent years, two types of plastics, hard thermoplastic polymers and soft thermoplastic elastomers, have been used for two-head injection molding. An all-glass molded body formed by simultaneous molding using such materials has been developed as a vibration isolating material.

(Japanese Unexamined Patent Publication No. 56-66537) In such a plastic molded article, the soft thermoplastic elastomer has good thermal adhesion with the hard thermoplastic polymer (mainly polystyrene is used) and flexibility. Styrene-based thermoplastic elastomers such as styrene-butadiene copolymers are used because they have excellent properties.

(Problems in the Background Art) However, styrene-based thermoplastic elastomers generally have the disadvantage of poor heat resistance and weather resistance, and large amounts of creep. There is a problem, especially when this molded body is used as a vibration isolator in applications where loads are constantly applied to Toyonaka Uyasu, the amount of creep increases significantly as the temperature rises. There are 6 problems with putting away
One time.

(Object of the Invention) The present invention was made to solve these problems, and an object of the present invention is to provide a plastic molded article that has excellent heat resistance, particularly creep resistance at high temperatures, and is suitable as a vibration damping material. shall be.

(Summary of the Invention) That is, the plastic molded body of the present invention includes first and second molded body portions made of a hard thermoplastic polymer that are concentric and substantially spaced apart from each other, and the first molded body portion and the first molded body portion 81!2. and a third molded body part made of a thermoplastic elastomer extended between and fixed to the molded body parts, the third molded body part being made of a styrene-free thermoplastic material, and a third molded body part made of a thermoplastic elastomer. Normal temperature, crosslinkable, /
Rear-modified ethylene-vinyl acetate copolymer resin and 4
The resin composition is then crosslinked by mixing at a weight ratio ranging from 0:60 to 95:5. It's slight.

An example of the plastic molded article of the present invention is shown in FIG. In the figure, numerals 1 and 2 respectively designate inner and outer molded body parts of a hard thermoplastic polymer concentrically and substantially spaced apart from each other, and numeral 3 denotes an inner and an outer molded body part made of a hard thermoplastic polymer, and numeral 3 is a thermoplastic polymer fixed therebetween. The intermediate molded body portion made of a plastic elastomer is shown.

Here, the hard thermoplastic polymers constituting the inner and outer molded body parts (1.2 tons) include polystyrene, polyphenylene oxide (ppo), acrylonitrile.
Butadiene styrene copolymer (ABS), polymethyl methacrylate, etc. 1-2 can be used. It is desirable that the inner molded body portion 1 and the outer molded body portion 2 be made of the same material. The intermediate molded body portion 3 is (A
) Styrene-based thermoplastic elastomer B) Composed of a soft thermoplastic elastomer mixed with silyl-modified EVA resin that can be crosslinked at room temperature, but as the styrene-based thermoplastic elastomer (A), , styrene-
Butadiene-styrene block copolymer (SBS) and styrene-ethylbutylene-styrene block copolymer (
SEBS) can be used heavily, and Matomo CB) can be cross-linked at room temperature with silyl-modified resin (DEVA resin and Teha, E
VAIC, 0.5 to 10 parts by weight of a trialkoxysilane such as vinyltrimethoxysilane (VTMO8);
0.01~2. A product obtained by heating and kneading OICC with a radical generator such as dicumyl peroxide (DCP) can be used.

In the present invention, such pellet-like (A) styrenic thermoplastic elastomer, (B) silyl-modified EV
By uniformly mixing resin A and disilanol condensation catalyst necessary for crosslinking this (B) silyl-modified EVA resin at a weight ratio of 40:60 to 95:5, the intermediate molded body portion 3t is obtained. - Consisting soft thermoplastic nidistomers are obtained.

The blending ratio of both components (A) and (B) O is limited to the above range.
If the blending amount of Hl (A) styrenic thermoplastic nidistomer is less than 40% by weight and the blending amount of (B) silyl-modified EVA resin exceeds 60 weight 11N, flexibility is insufficient.The blending amount of A resin is 5%. This is because if the weight is less than tX, the effect of improving the heat resistant creep property of the intermediate molded body portion 3 by adding the component (B) will not appear. The most desirable blending ratio (weight ratio) of these two components, i, A:B, is in the range of 60:40 to 80:20.

Furthermore, the VC in such a soft thermoplastic elastomer and in the hard thermoplastic polymer constituting the inner and outer molded body parts 1.2t may contain reinforcing agents, fillers, softeners, colorants, It is also possible to add an appropriate amount of property improvers such as stabilizers.

In order to manufacture the plastic molded article constructed as described above in the present invention, it is desirable to employ a simultaneous bottom molding method using a two-head injection molding machine as shown below, for example.

That is, as shown in Fig. 82, mold cavities 4 and 2, each having a predetermined shape and concentrically spaced apart from each other, are heated and melted using an injection molding machine. Rigid thermoplastic polymer 6t - injection filled t
After that, when the polymer 6 is still hot and solidified, the core γ is moved back to the position shown in FIG. 3 to open the third mold cavity 8, where it is heated and melted by an injection molding machine. Thermoplastic elastomer 9t containing silanol condensation catalyst - injection filling.

Next, the whole is cooled to room temperature, the mold is opened, and the molded body is completely collapsed, and then the thermoplastic elastomer containing the silanol condensation catalyst (silyl-modified EVA resin component) is crosslinked by leaving it at room temperature or heating it. let

In this way, a fabric made of a hard thermoplastic polymer and @
An fLfc plastic molded body is obtained, which is composed of a molded body part 2 and a molded body part @3 made of a crosslinked thermoplastic elastomer, which is bonded between them with a well-defined boundary surface.

In the present invention, in order to increase the adhesion between the first and second molded body parts and the i3 molded body part, the adhesive surfaces of the first and second molded body parts that are in contact with the third molded body part are It is desirable to pre-process the material at low temperature.

That is, first and second molded body parts are manufactured by injection molding or compression molding a hard thermoplastic polymer, and these are placed facing the anode in a vacuum container, with f'L7 being the anode. high-frequency power is applied between the electrodes to perform low-temperature plasma processing. After preheating in this way,
The first and second molded body parts are attached to predetermined parts of the mold, and then a thermoplastic elastomer is injected and filled into the mold cavity between them, and crosslinked to form a third molded body part t-
By forming the bottom, the third molded body part is firmly bonded between the part 1 and the second molded body part f'L7? A nigerastic molded body is obtained.

(Example of the invention) Examples of the present invention will be described below.

EXAMPLE In the method of simultaneous injection molding described above, the inner and outer molded body parts 1.2 were made of polystyrene, and the molded body part 3 intermediate between them was composed of a soft thermoplastic nystomer having the composition shown in the table below. A friend who manufactures a plastic molded body with the shape shown in Figure 1.

Of the ingredients constituting the absorptive Q thermoplastic elastomer, silyl-modified 1. i'A resin fl, EVA100i
Amount g [82.0 parts by weight of VTMO and 2 parts by weight of DCPo were mixed together and heated and kneaded, which was then put into an injection molding machine together with SBS and further processed into DBTDL.

The masterbatch was added, heated and kneaded, and the material was injection molded to form an intermediate molded product.After cooling, it was left at a temperature of 40°C for one week to completely crosslink the material.

For comparison, an intermediate molded body portion 3 was molded in the same manner using a soft thermoplastic nidistomer having a different composition.

In order to learn about the properties of the plastic molded bodies of Examples and Comparative Examples thus obtained as vibration damping materials, the spring constants of each were measured. 6 at temperatures of 40°C and 50°C
Leave it for 0 minutes and measure the amount of creep after t.

The measurement results are shown in the bottom column of the following table.From these measurement results, it can be seen that the higher the spring constant, the higher the spring constant of the comparative example molded product made of thermoplastic elastomer containing no or almost no silyl-modified EVA. Although the amount of creep increases, it can be seen that in the molded bodies of Examples, the spring constant increases as the content of silyl-modified EVA increases, but the creep f/k actually decreases.

(Effects of the Invention) As described above, the plastic molded article of the present invention is made of a crosslinked first and second molded article portion made of a hard thermoplastic polymer and a soft thermoplastic elastomer blended with a silyl-modified BVA resin. Since it is composed of a third molded body portion, it has excellent heat resistance, particularly creep characteristics at high temperatures, and is suitable as a vibration isolating material.

Furthermore, the molded product of the present invention can be efficiently mass-produced by simultaneously forming the bottom shape using a two-head injection molding machine.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an example of the plastic molded article of the present invention, and FIGS. 2 and 3 are ninth cross-sectional views illustrating a method for injection molding the molded article of the present invention. 1・・・・・・・・・・・・・・・・・・・・・Inner molded body part 2・・・・・・・・・・・・・・・・・・・
...Outer molded body part 3...
・・・・・・－・・・・・・Intermediate molded body part 6・・・・・・
・・・・・−・・・・・・・・・・・・Hard thermoplastic polymer 9・・・・・・・・・・・・・・・・・・・・・
・Plastic elastomer Figure 1

Claims (1)

[Claims] 1. Concentric and substantially spaced apart first and second molded body parts made of a hard thermoplastic polymer, and between the first molded body part and the second molded body part; A plastic molded body comprising a third molded body part made of a thermoplastic elastomer extended and fixed thereto, the third molded body part comprising a styrene-based thermoplastic elastomer and a silyl-modified ethylene-forming body that is crosslinkable at room temperature. Plastic molded article 2, first and second moldings, characterized in that the resin composition is crosslinked with a vinyl acetate copolymer resin at a weight ratio in the range of 40:60 to 95:5. 2. The plastic molded article according to claim 1, wherein the surface of the body portion that comes into contact with the third molded body portion is activated by being previously subjected to low-temperature plasma treatment.