KR100220077B1 - Preparation process of rubberish foam - Google Patents

Abstract

The present invention relates to a method for producing a rubber-based foam excellent in shock absorption, and more particularly, a filler, a tackifier, in a polymer system using a composite of nitrile rubber and polyvinyl chloride resin alone or blended various resins and rubber, By adding a crosslinking agent, a foaming agent and other additives, the present invention relates to a method for producing a rubber-based foam having low specific gravity, excellent physical properties such as lightness and abrasion resistance, and excellent shock absorption.

Description

Manufacturing method of rubber foam excellent in shock absorption

The present invention relates to a method for producing a rubber-based foam excellent in shock absorption, and more particularly, using a composite of nitrile rubber and polyvinyl chloride resin alone or a blend of various resins and rubbers in the composite. The present invention relates to a method for producing a foam having a low specific gravity, excellent abrasion resistance and various physical properties, and excellent shock absorption by inserting a filler, a tackifier, a crosslinking agent, a foaming agent, and other additives.

Currently, the footwear industry uses a lot of shock absorbers as functional parts to improve the fit and shock absorbency by using a variety of polymers as a base material attached to the site that requires the shock absorber of the shoe.

Shock absorbers for shoes can be largely divided into foam and non-foaming body.

As foams, impact absorbing materials are typically manufactured using ethylene propylene diene rubber or ethylene vinyl acetate rubber as base materials. However, these foams have the advantages of being lighter than non-foaming materials, but they have low impact absorption properties and poor physical properties. Have

On the other hand, non-foaming products are manufactured with shock absorbers using polynorbornene rubber and silicone gel, which are relatively good in absorbing shock, but are expensive due to the high unit cost of rubber itself, which is expensive and has a higher specific gravity than foam. It has a bad disadvantage.

In addition, the existing shock absorbers were not good enough to be used as the material of the sole, all of them were attached to the inside of the midsole of the shoe or the bottom of the insole was used only as a local interior material.

However, when used as an interior material, it does not absorb sufficiently the shock transmitted from the ground during walking, driving or exercising, but partially absorbs the shock after the shock has already been transmitted and distributed to the outsole, thus functioning as a practical shock absorber. It was difficult to exert all.

Therefore, there is a demand for the development of a functional material that can directly absorb the impact transmitted from the ground by mounting the most impact on the outsole of the shoe.

Accordingly, in the present invention, a composite of nitrile rubber and polyvinyl chloride resin is used as a base material, and various additives are mixed to prepare a foam through a conventional general rubber processing process, and the specific gravity is low, but the impact absorption is excellent and the physical properties are excellent. Rubber-based foams can be used that can be used as general industrial subsidiary materials that require outsole and impact absorption.

The molding process for producing a rubber-based foam having a low specific gravity, light weight and excellent shock absorption and physical properties is as follows.

First, a compound containing a crosslinking agent, a blowing agent, and other additives in a polymer system based on a composite of nitrile rubber and polyvinyl chloride resin was prepared in a sheet, and then introduced into a closed mold. Press process at high temperature and high pressure of 180 ℃ and 100-160kg / ㎠ for 5-20 minutes to decompose the crosslinking agent and foaming agent, and then open the mold momentarily to remove the pressure and then expand rapidly by using pressure difference. As described above, a foam having a skin layer on the surface and having an independent bubble structure therein is prepared.

The present invention is a single step process without reshaping or other complicated processing process, excellent physical properties including mechanical properties, light weight and excellent shock absorption, can be mounted on the outsole of the shoe and can be used as general industrial materials The purpose is to produce crosslinked foamed functional foams having a bubble structure.

Hereinafter, the present invention will be described in detail.

The present invention is based on a composite of nitrile rubber and polyvinyl chloride resin, which is used alone or by blending other rubbers and resins as a polymer system, and press-foaming a compound containing a crosslinking agent, a foaming agent and other additives therein. It is characterized by.

The composition of the shock-absorbing foam in the present invention uses a composite of nitrile rubber and polyvinyl chloride resin having a blend composition ratio of 90:10 to 60:40 of nitrile rubber and polyvinyl chloride resin.

As the polymer system, a composite of nitrile rubber and polyvinyl chloride resin may be used alone, or 95-50 parts by weight of the composite may be used and 5-50 parts by weight of rubber or resin may be used.

If the amount of the rubber or resin for the blend is less than 5 parts by weight, the blending effect is not seen. If the amount is exceeded 50 parts by weight, the specific gravity of the foam becomes high and the overall physical properties including impact absorbing properties are lowered, and a stable bubble cannot be obtained.

Rubbers and resins for blends used in the manufacture of impact-absorbing foams of the present invention are isoprene rubber, natural rubber, styrene-butadiene rubber, ethylene-propylene rubber, ethylene-propylene-diene-copolymer, 1,2-poly Butadiene rubber, liquid isoprene rubber, liquid chloride rubber, liquid polybutadiene rubber, liquid ethylene-propylene-diene rubber, silicone rubber, butyl rubber, styrene-isoprene-styrene copolymer, styrene-butadiene-styrene copolymer, styrene- Ethylene / butylene-styrene copolymers, ionomer resins, polyethylene, chlorinated polyethylene, chlorosulfonated polyethylene and kneaded polyurethanes.

Fillers, tackifiers, foaming agents, crosslinking agents and metal oxides and, if necessary, foaming aids, crosslinking aids, stabilizers and other additives are added to the substrate consisting of such components in the preparation of the foam of the present invention.

In the present invention, 5-50 parts by weight of calcium carbonate, magnesium carbonate, barium sulfate, calcium sulfate, silica, clay, carbon black, and modified substances thereof are used as a filler, and the amount thereof is less than 5 parts by weight. If the back surface does not exhibit a filling effect and exceeds 50 parts by weight, the specific gravity increases and the overall physical properties decrease.

As the tackifier, not only tackifiers such as rosin-based, terpene-based, petroleum-based resins, but also liquid polymer materials used as the rubber for the blend may be used, and the amount of the tackifier may be 2-30 parts by weight.

At this time, if the amount is less than 2 parts by weight, the additive effect does not appear. If the amount is more than 30 parts by weight, the specific gravity is rapidly increased, and in some cases, the hardness is rapidly increased, making it difficult to use as a shoe sole material.

Examples of the blowing agent include azo compounds such as azotigarbonamide having a decomposition temperature of 130 to 200 ° C., nitroso compounds such as N and N'-dinitrosopentamethylenetetraamine, azobisisobutyronitrile and P-toluene. 1-20 parts by weight of sulfonylhydrazine, P, P'-oxybis (benzenesulfonylhydrazide), diazoaminoazobenzene and the like are used with respect to 100 parts by weight of the substrate, and the amount of the foam obtained is less than 1 part by weight. High hardness, high specific gravity, and exceeding 20 parts by weight, it is impossible to obtain a uniform bubble due to a sudden expansion beyond the limit of high temperature viscoelasticity of the polymer.

In addition, 0.2-4 parts by weight or 100 parts by weight of the organic peroxide crosslinking agent based on 100 parts by weight of the sulfur and insoluble sulfur material base in order to sufficiently capture the decomposition gas generated above the decomposition temperature of the blowing agent and impart high temperature viscoelasticity to the polymer. Use 3-4 parts by weight.

If the amount of sulfur or insoluble sulfur is less than 0.2 parts by weight, the crosslinking is insufficient, and thus the polymer is not maintained at high temperature viscoelasticity during decomposition of the presenting agent. If the amount is more than 4 parts by weight, the hardness is rapidly increased and the foam becomes unstable.

Even when the organic peroxide is used as a crosslinking agent, if the amount used is less than 0.3 part by weight, the polymer is not maintained at high temperature viscoelasticity, and thus the foam becomes unstable. When the amount is more than 4 parts by weight, the specific gravity of the foam is high and the hardness is increased, thereby decreasing the stability of the foam. .

Organic peroxide crosslinkers that can be used include t-butylperoxyisopropyl carbonate, t-butylperoxylaurylate, t-butylperoxyacetate, di-t-butyldiperoxyphthalate, t-dibutylperoxymaleic acid , Cyclohexanone peroxide t-butyl cumyl peroxide, t-butyl hydroperoxide, t-butyl peroxybenzoate, dicumyl peroxide, 1,3-bis (t-butylperoxyisopropyl) benzene, methyl ethyl ketone Peroxide, 2,5-dimethyl-2,5-di (benzoylperoxy) nucleic acid, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, di-t-butylperoxide, 2 , 5-dimethyl-2,5 (t-butylperoxy) -3-hexane, n-butyl-4,4-bis (t-butylperoxy) valerate, a, a'-bis (t-butylper Oxy) diisopropylbenzene and the like.

When sulfur or insoluble sulfur is used as a crosslinking agent, a vulcanization accelerator may be used in an amount of 0.01-3 parts by weight. If the amount is less than 0.01 parts by weight, the crosslinking time may not be shortened. Although it shows a shortening effect, the hardness of the foamed product becomes high and blooms.

As vulcanization accelerator, aldehyde ammonia vulcanization accelerator, aldehyde amine vulcanization accelerator, guanidine vulcanization accelerator, thiourea vulcanization accelerator, thiazole vulcanization accelerator, thiuram vulcanization accelerator, dithiocarbamate vulcanization accelerator, xanthate vulcanization accelerator Accelerators etc. can be used individually or in mixture.

When crosslinking the organic peroxide, a small amount of sulfur, triallyl cyanurate, triallyl isocyanurate, trimethylolpropane trimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, butyl Len glycol acrylate, butylene glycol dimethacrylate and metal-acrylate, metal-methacrylate, etc. can be used 0.1-5 weight part with respect to 100 weight part of base materials.

On the other hand, metal oxides such as cadmium oxide, zinc oxide, magnesium oxide, mercury oxide, tin oxide, lead oxide, calcium oxide, stearic acid, zinc stearate, zinc carbonate, calcium carbonate, barium stearate, etc. 1-4 parts by weight based on 100 parts by weight of the base material can be used.

In particular, the metal oxide also serves as a decomposition aid of the presenting agent.

In addition, as the foaming aid, 0, 5-8 parts by weight of urea and urea derivatives may be added to 100 parts by weight of the base material.

The mixture is kneaded sufficiently by using a banbury mixer, an open roll mill or a kneader in a temperature range above the melting point of the substrate and below the decomposition point of the crosslinking agent and the blowing agent. After making the mold, it is sheeted appropriately for press molding and put into the mold.

At this time, after pressing for 5-20 minutes under the conditions of temperature 150-180 ℃, pressure 150-160kg / ㎠ to open the mold to obtain a product by producing a foam.

The shock absorbing foam produced by the manufacturing method of the present invention as described above has a coating layer on the surface, the foaming ratio (size ratio) is 1.02-2 times, specific gravity 0.3-0.95, and is lighter than the conventional shock absorbing sheet. It has excellent appearance without tearing or scratching, and has excellent adhesion with outsole and midsole in shoes as well as significantly improved physical properties such as shock absorption and abrasion resistance.

Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited by an Example.

Example 1

20 parts by weight of tackifier, 20 parts by weight of filler and lubricant, lubricant and process oil are added to 100 parts by weight of the composite of nitrile rubber and polyvinyl chloride resin having a blend ratio of nitrile rubber and polyvinyl chloride resin of 70:30. After kneading for about 15 minutes in a kneader having a temperature of 60-70 ° C., a crosslinking agent and a blowing agent were added to the kneaded material under water having a surface temperature of 60-70 ° C., and further kneaded for about 10 minutes to prepare a sheet-like kneaded product.

This was put into a mold under the conditions of 150 ° C. and 150 kg / cm 2, and press molded for 10 minutes to prepare a foaming agent having a desired shape.

The obtained foam had a specific gravity of 0.6, and was light, but also excellent in shock absorption and wear resistance. The physical properties of the foam are shown in Table 2.

Example 2

A foam was prepared in the same manner as in Example 1 by blending a liquid tackifier and various additives to 100 parts by weight of a composite of nitrile rubber and polyvinyl chloride resin.

The results of measuring the physical properties of the foams are shown in Table 2, and the resulting foams have a specific gravity of 0.63, which is light but excellent in shock absorption and abrasion resistance.

Example 3

80 parts by weight of the composite of nitrile rubber and polyvinyl chloride resin and 20 parts by weight of butyl rubber having excellent shock absorbing properties were blended with liquid isoprene rubber and terpene resin as a tackifier, and the additives shown in Table 1 were introduced to provide the same additives as in Example 1. The properties of the foams molded by the method are shown in Table 2.

The specific gravity of the foam was 0.7, and the shock absorption characteristics were excellent, but the wear resistance was particularly excellent.

Example 4

In a polymer system blended with 70 parts by weight of a composite of nitrile rubber and polyvinyl chloride resin and 30 parts by weight of butyl rubber, a mixture of liquid isoprene rubber and terpene resin is added as a tackifier and mixed with various additives. The properties of the foams foamed by crosslinking with seeds (DCP) are shown in Table 2.

The prepared foam had a specific gravity of 0.6 and was light and excellent in shock absorption.

[Comparative Example]

The physical properties of the shock absorbing sheet currently commonly used are measured and shown in the properties of Comparative Example of Table 2.

The characteristics of the shock absorber using polynorbornene rubber-based shock absorbing sheet (Comparative Example 1) and silicone gel (Comparative Example 2) showed that the specific gravity was 1.27 and 1.32, and the shock absorbency was relatively good. Abrasion resistance is 21-25%, which is difficult to use for shoe outsole.

On the other hand, the sponge-type shock absorbing sheet based on ethylene vinyl acetate copolymer had a low specific gravity of 0.4, which was light, but the shock absorbency was not good compared with other materials, and the wear resistance was also poor.

TABLE 1

TABLE 2

1) Comparative Example 1: Rubber sheet based on polynorbornene rubber

2) Comparative Example 2: Shock Absorber Based on Silicone Gel

3) Comparative Example 3: Sponge Sheet Based on Ethylene Vinyl Acetate

Claims (5)

Crosslinked foaming is achieved by using a composite of nitrile rubber and polyvinyl chloride as a base material or by using a blended product made of various rubbers or resins as a polymer system by pressing a compound containing crosslinking agent, foaming agent and other additives. Method for producing a rubber-based foam excellent in shock absorption characterized in that the production. The method for producing a rubber-based foam having excellent impact absorption properties according to claim 1, wherein the nitrile rubber and the polyvinyl chloride resin have a content ratio of 90:10 to 60:40. The rubber-based foam having excellent shock absorbing properties according to claim 1, wherein 5-50 parts by weight of at least one polymer selected from a resin and rubber for blending is added to 95-50 parts by weight of nitrile rubber and polyvinyl chloride resin. Manufacturing method. The rubber and resin for the blend is isoprene rubber, natural rubber, ethylene-propylene rubber, ethylene-propylene-diene copolymer, 1,2-polybutadiene rubber, liquid isoprene rubber, liquid rubber chloride, Liquid polybutadiene rubber, liquid ethylene-propylene-diene rubber, silicone rubber, butyl rubber, ethylene vinyl acetate copolymer, ethylene ethyl acetate copolymer, liquid ethylene-propylene rubber, ionomer resin (lonomer), polyethylene, chlorinated polyethylene, chlorosulfur A method for producing a rubber-based foam having excellent shock absorbency using a fonated polyethylene and a kneaded polyurethane. The method for producing a rubber-based foam having excellent shock absorbency according to claim 1, which is prepared by introducing and foaming a liquid rubber, a tackifier, a process oil, etc. in order to improve the shock absorbency.