JPH08258081A - Mold foaming connection molding method of thermoplastic elastomer - Google Patents

Abstract

PURPOSE: To form the transfer molded part of foam of a thermoplastic elastomer of good quality reduced in compression permanent strain. CONSTITUTION: A thermoplastic elastomer 10 and a polymer 20 preliminarily compounded with a foaming agent are prepared and both of them are quantitatively supplied in a definite ratio by quantitative feeders 30, 40 and mixed by the feed screw of an injection molding machine 50 to be injected into a mold adjusted to predetermined temp. and bonded to the extrusion vulcanized rubber or extrusion molded resin incorporated in the mold simultaneously with molding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of foaming and splicing a thermoplastic elastomer into a mold.

[0002]

2. Description of the Related Art Heretofore, a method has been tried in which a transfer-molded portion having a thermoplastic elastomer as a base material is made into a foam with respect to an extruded vulcanized rubber or an extruded resin. It has not been converted.

(A) When a foaming agent having a decomposition and foaming temperature lower than the softening temperature of the thermoplastic elastomer is mixed, foaming occurs at that time and does not contribute to foaming during the subsequent molding. (A) When a foaming agent having a decomposition and foaming temperature higher than the softening temperature of the thermoplastic elastomer is mixed, it does not foam when injected into the mold. (C) When a powdered foaming agent is mixed with thermoplastic elastomer pellets at room temperature and supplied to an injection molding machine, if the amount of the foaming agent is large, the foaming agent will separate from the surface of the thermoplastic elastomer and a uniform foam will be obtained. Disappear.

[0004]

The problem to be solved is that a method for foaming a transfer-molded portion having a thermoplastic elastomer as a base material with respect to the conventional extruded vulcanized rubber or extruded resin described above is not available. The present invention is that when the foaming agent is mixed, it does not foam when injected into a mold, or that a uniform foam cannot be obtained. A mold foam connection molding method is provided.

[0005]

Means for Solving the Problems An explanation will be given with reference to FIG. The first aspect of the invention is to prepare a thermoplastic elastomer 10 and a foaming agent polymer 20 in which a foaming agent is preliminarily mixed, and both are quantitatively supplied at a constant ratio by the constant quantity feeders 30 and 40. The heat which is characterized by mixing with a feed screw and pouring it into a mold whose temperature is adjusted to a predetermined temperature, and simultaneously adhering to the extruded vulcanized rubber or extruded resin incorporated in the mold at the same time as molding. It is a method of foaming and splicing molding of a plastic elastomer.

In a second aspect of the present invention, in the composition of the first aspect, the blowing agent polymer 20 is used in an amount of 50 to 50 parts by weight of the blowing agent with respect to 100 parts by weight of ethylene / propylene rubber, ethylene / butene resin or ethylene vinyl acetate copolymer. 90 parts by weight are mixed, and the ratio of the thermoplastic elastomer 10 to the foaming agent polymer 20 is 1 to 20 parts by weight, preferably 6 to 15 parts by weight with respect to 100 parts by weight of the former, Moreover, the mold temperature of the injection molding machine 50 which mixes and supplies both is 0-80 degreeC, Preferably it is 30-50 degreeC, It is characterized by the above-mentioned.

A third invention is, in addition to the constitution of the first or second invention, the foaming agent is azodicarbondiamide or benzenesulfonylhydrazide.

[0008]

EXAMPLE An example of the present invention will be described with reference to FIG. 1. 10 is a thermoplastic elastomer, 20 is an ethylene-propylene rubber, an ethylene-butene resin, or an ethylene-vinyl acetate copolymer containing a foaming agent. It is an agent polymer (foaming agent masterbatch), which is obtained by mixing 50 to 90 parts by weight of a blowing agent with 100 parts by weight of ethylene / propylene rubber, ethylene / butene resin or ethylene vinyl acetate copolymer. As the foaming agent, azodicarbondiamide or benzenesulfonylhydrazide is used.

Numerals 30 and 40 designate a thermoplastic elastomer 10 and a hopper 35 for packing a foaming agent polymer 20, respectively.
45 is a fixed-quantity feeder connected to 45, and 50 is an injection molding machine for molding the extruded vulcanized rubber or extruded resin supplied thereto, and at the same time foaming the thermoplastic elastomer 10 and the foaming agent polymer 20 as transfer molding parts. It is a device that embodies and bonds. Reference numeral 55 is a hopper that receives the thermoplastic elastomer 10 and the foaming agent polymer 20 discharged from the fixed quantity feeders 30 and 40 and supplies them to the injection molding machine 50.

For the extruded vulcanized rubber or the extruded resin, the thermoplastic elastomer 10 and the foaming agent polymer 20 are used.
The following operation is performed to make the transfer molded part made of the foam into a foam.

First, the thermoplastic elastomer 10 and the foaming agent polymer 20 are packed in the hoppers 35 and 45, respectively, and the former is 100 parts by weight and the latter is 1 to 20 parts by weight by the quantitative feeders 30 and 40. Preferably 6-15
A fixed amount of parts by weight is supplied in a fixed amount, mixed by a feed screw (not shown) of the injection molding machine 50, and injected into a mold whose temperature is adjusted to a predetermined temperature.

The foaming aid polymer 20 is obtained by previously blending 50 to 90 parts by weight of a blowing agent with 100 parts by weight of ethylene / propylene rubber, ethylene / butene resin or ethylene vinyl acetate copolymer. As the foaming agent, azodicarbondiamide or benzenesulfonylhydrazide is preferable. Further, the temperature at the time of mixing the thermoplastic elastomer 10 and the foaming aid polymer 20 with the feed screw of the injection molding machine and injecting them into the mold must be adjusted to 0 to 80 ° C, preferably 30 to 50 ° C. There is.

[0013]

The function of the extruded vulcanized rubber or extruded resin incorporated in the mold is obtained by previously mixing the foaming agent into a rubber or resin that can be mixed at a temperature below its decomposition temperature in a high concentration and performing the above operation. At the same time as molding, molding and foaming adhesion of the thermoplastic elastomer are performed to form a transfer molding portion of a foam of good quality thermoplastic elastomer with less compression set.

[0014]

Since the present invention is configured as described above,
At the same time as molding of extruded vulcanized rubber or extruded resin incorporated in a mold, molding and foaming adhesion of a thermoplastic elastomer are performed, and a transfer molding part of a foam of good quality thermoplastic elastomer with less compression set is formed. .

[Brief description of drawings]

FIG. 1 is a front view showing an apparatus used in an embodiment of the present invention.

[Explanation of symbols]

 10 Thermoplastic Elastomer 20 Foaming Agent Polymer 30 Quantitative Feeder 40 Quantitative Feeder 35 Hopper 45 Hopper 50 Injection Molding Machine 55 Hopper

Claims (3)

[Claims] 1. A thermoplastic elastomer (10) and a foaming agent polymer (20) in which a foaming agent is preliminarily blended are prepared, and both are quantitatively supplied at a constant ratio by a constant quantity feeder (30, 40). , Mixing with a feed screw of an injection molding machine (50), injecting it into a mold whose temperature is adjusted to a predetermined temperature, and simultaneously adhering it to extruded vulcanized rubber or extruded resin incorporated in the mold at the same time as molding. A method for molding, foaming, splicing and connecting a thermoplastic elastomer to a die. 2. A foaming agent polymer (20) is obtained by blending 50 to 90 parts by weight of a blowing agent with respect to 100 parts by weight of ethylene / propylene rubber, ethylene / butene resin or ethylene vinyl acetate copolymer. The ratio of the plastic elastomer (10) to the foaming agent polymer (20) is 1 to 20 parts by weight, preferably 6 to 15 parts by weight with respect to 100 parts by weight of the former, and both are mixed. The mold temperature of the injection molding machine (50) to be supplied is 0 to 80.
C., preferably 30 to 50.degree. C., The method for molding and foaming a thermoplastic elastomer mold according to claim 1, wherein the temperature is 30.degree. 3. The method for foaming splicing and molding of a thermoplastic elastomer mold according to claim 1, wherein the foaming agent is azodicarbondiamide or benzenesulfonylhydrazide.