JPS6090226A - Vulcanized foam - Google Patents

Abstract

PURPOSE:A vulcanized foam, obtained by incorporating a specific 1,2-polybutadiene, etc. with a foaming agent, and the respective specific amounts of thiuram based vulcanizing agent and sulfur, and having improved tear strength, permanent set in fatigue, hue, etc. at a high expansion ratio. CONSTITUTION:A vulcanized foam obtained by (A) 100pts.wt. mixture consisting of (i) 30-100wt% 1,2-polybutadiene having >=70% vinyl bond content, >=5% crystallinity and >=0.5dl/g intrinsic viscosity with (ii) 0-70wt%, preferably 10- 60wt% block copolymer of natural rubber or diene based synthetic rubber and an aromatic vinyl compound and a conjugated diene compound with (B) 0.6- 2.5pts.wt. thiuram based vulcanization accelerator, preferably tetramethylthiuram disulfide, (C) 0.05-0.5pts.wt. sulfur and (D) preferably 2-15pts.wt. foaming agent. USE:A material for wastes and packaging materials, etc.

Description

Detailed Description of the Invention The present invention provides 1,2-polybutadiene (hereinafter referred to as 1.2-PBD), which has a high expansion ratio, large tear residue, little fading, and excellent color tone. ) relating to proprietary cross-linked vulcanized foams.

1.2-PBD as a crosslinked foam with rubber elasticity;
Foams using ethylene/vinyl acetate copolymer (EVA), natural rubber, synthetic rubber, and the like are known. Among these, foams using natural rubber and synthetic rubber have drawbacks such as difficulty in obtaining a high expansion ratio and large shrinkage after crosslinking, which prevents them from being used in applications requiring dimensional stacking.

On the other hand, it is known that foams using 1.2- PBD and EVA can be obtained with a high expansion ratio without shrinkage problems with only one step of vulcanization. For example, it is widely used in applications that require 4ilt, such as outer soles, inner soles, and midsoles of sports shoes.

However, foams using EvA have practical problems of poor rubber elasticity and large settling (<permanent strain after back compression).

1.2- Although PBD foam has higher rubber elasticity than EVA, it is essential to have a high expansion ratio (more than 3 times the expansion ratio) in order to reduce the weight. There are disadvantages in that mechanical properties such as strength are reduced and sag increases.

In particular, tear strength is an important property for sports shoe sole materials, as is adhesive strength; if tear strength is low, breakage such as cracking occurs during use, reducing the durability of shoes.

In addition, if the heaviness is large, the material will not be able to fully exhibit its performance as a cushioning material, reducing its shock absorbing properties during running, etc., and having various effects on the human body.

Therefore, the present inventors conducted extensive studies to solve the above-mentioned problems of 1.2-PBD foams. As a result,
1.2- By blending a rubber component with a specific composition into PBD, and paying special consideration to the sulfur added to the freshener, the type of vulcanization accelerator, and the composition, it is possible to achieve a high expansion ratio while maintaining tear strength, stickiness, and color tone. It has been discovered that a crosslinked vulcanized foam having excellent physical properties such as the following can be obtained, and the present invention has been achieved. That is, the vulcanized foam of the present invention has: (4) a vinyl-bonded gold-containing salmon with a crystallization strength of 70 or more;
1,2-polybutadiene 30 to 100%, with an intrinsic viscosity [η] (measured in toluene at 30°C) of 0.5 dll'11 or more, and (B) natural rubber, diene-based synthesis 14 selected from rubber, and a block copolymer of an aromatic vinyl compound and a conjugated diene compound (hereinafter referred to as TR) [or two or more types]
・0 to 70 it%.

A mixture consisting of [(4) + (B)) 100 parts per part, (C) Thiuram vulcanization accelerator 0.6 to 2.5 parts, (B) Sulfur 0.05 to 0.5 parts It is characterized by containing a foaming agent.

The present invention will be explained in more detail below.

In the 1.2-PBD of (4) used in the present invention, in order to obtain a foam with a uniform cell structure, the vinyl bonded metal content is 7.
It is 1.2-PBD with a crystallinity of 0-85% or more, preferably 5ts or more, and preferably 1ilO-40%. Although the molecular weight can be selected over a wide range, in order to obtain a high expansion ratio and a uniform and fine foam, which is the objective of the present invention, the above [η] should be 0.5 di/1.
/ or more is required.

[η] is more preferably 1.0 to 3.0 dt/I.

Blend used in the present invention with 1.2-” PBD (B)
The natural rubber, diene-based synthetic rubber, and TR are mainly used to adjust the hardness of the crosslinked foam. Typical rubbers other than TR include the above-mentioned natural rubber (NR), cis-polyinoprene rubber (IR), styrene-butadiene copolymer rubber (SBR), and polybutadiene rubber (BR).

Examples include diene-based synthetic rubbers such as acrylonitrile-butadiene rubber (NBR) and cycloprene rubber (CR). Among these, preferred rubbers include natural rubber, cis-polyiso!ene rubber, etc. Provides preferable foamability. Also, as TR, polystyrene-polycitadiene block copolymer, polysterene-polybutadiene-polysterene block copolymer, polystyrene-poly(styrene-butadiene)-,
I listerene block copolymer, polysterene-polyimprene-polystene block copolymer, stele>
A block copolymer of an aromatic vinyl compound and a conjugated diolefin, such as a block copolymer of each of the above-mentioned four types in which a part or all of 4 is substituted with α-methylstyrene, and hydrogen of these pro- and diolefin copolymers. It's caused by some kind of monster. this house,
The block copolymer used in the present invention is preferably a polysterene-polybutadiene-polysterene pro-copolymer.

The self-combination of (4) and (B) is (4)/(B)=
30-100/70-0, preferably 40-9
0760-10. If the amount of (A) is less than 30% by weight, a foam with a crystallization ratio as high as θ will be obtained, and the shrinkage will also be large.

The thiuram thread device accelerator (C) used in the present invention is:
A thiuram-based vulcanization accelerator that releases sulfur during vulcanization is used, specifically tetramethylthiuram disulfide (T
MTD), tetraethelthiuram disulfide (TE
TD), tetrabuterthiuram disulfide (TBT)
D) , dipentamethylenethiuram tetrasulfide (
Among them, tetramethylthiuram disulfide is preferred from the viewpoint of scorch resistance, melting point, etc.

The amount of thiuram-based vulcanization accelerator necessary to obtain the effects of the present invention is as follows: [(4)+(B))]
0.6 to 2.5 double waves, preferably 1. □J
2.0 times 5 times. If the blended silk of the thiuram-based vulcanization accelerator is less than 0.6 parts, the degree of crosslinking will be too low, the distortion will be large, and the desired crosslinked foam will not be obtained. Also, 2.5
If the weight exceeds 50%, the degree of crosslinking will be too high and it will be difficult to obtain a foam with the targeted high expansion ratio.

In addition, the blending lit of sulfur in (B) necessary to obtain the effects of the present invention is 0.05 to 0, sIL parts per 100 parts by weight of the mixture [(4) (B)], Preferably 0
．． 1 to 0.3 parts by weight. When the blending value of sulfur is less than 0.05 parts, the effect of adding sulfur is hardly seen. Moreover, if it exceeds 0.5 layers, the degree of crosslinking will become too high, making it difficult to obtain a foam with a targeted high expansion ratio, and the color tone will also deteriorate.

Further, in the present invention, adding a thiazole-based accelerator to the vulcanization system is effective in preventing scorch and plume. Examples of thiazole promoters include 2-mercaptobenzotheazole (MBT), +dipenzotheazyl disulfide (MBTS), and N-cyclohexyl-2-pencinaacyl sulfene 7 ml' (CBS).

N-oxydiethylene-2-benzothiazyl sulfenamide (OBS), N-tertiary butyl-2-benzotheazyl sulfenamide (BBS), etc. The preferred blending value of these thiazole accelerators to achieve the above effect is mixture [ω+(B)) 100Jk
Preferably 2.0 parts by weight or less, 0.3 to 1 part
2.0 parts by weight is more preferred.

Inorganic or organic blowing agents, known as blowing agents, may be used in the foam compositions of the present invention. Examples of blowing agents include sodium bicarbonate, ammonium bicarbonate, sodium carbonate, and ammonium carbonate.

Azogical? Examples include dinitrone terephthalamide (DNPT), dinitrone terephthalamide, azobisisobutyronide 1-nor, barium azodicarcanoate, sulfonyl hydrazide, toluenesulfonyl hydrazide, and the like. These foaming agents may be used in combination with known foaming aids such as urea and urinary chloride conductors. The amount of blowing agent used is the mixture [(4)
+(B)] It is preferably 1 to 30 parts by weight, more preferably 2 to 15 parts by weight, per 100 parts by weight. If the blowing agent is less than 1 part by weight, only a foam with a low expansion ratio will be obtained;
If the weight is higher than 0 weight, a large amount of gas will be generated due to the decomposition of the blowing agent, and the gas pressure will be too high, which may cause cracks in the resulting foam.

In addition to the above-mentioned (A) to (E), the foam composition of the present invention also contains additives that are included in general compositions, such as reinforcing agents, fillers, anti-aging agents, and processing aids. agent.

There is no problem in adding a softening agent or the like as appropriate.

(4) - (There are no particular restrictions on the method of mixing the mixture and other compounding agents, including a pant-arm mixer, pressurized knee mixer,
Any mixing method used for general comb formulations such as open rolls may be used, and it is preferable to mix at an eccentric position in the range of 70 to 140°C. The mixture thus obtained is fed into a mold and heated to 130-180°C, preferably 140-110°C, under pressure.
The compound is crosslinked and the blowing agent is decomposed by heating in a direct temperature range of 70° C. and at a temperature higher than the decomposition temperature of the blowing agent.

The clamping pressure of the mold is required to substantially suppress the expansion of gas generated by decomposition of the blowing agent, and is usually 80'ky.
This is carried out under pressure of /cm2 or more.

Yumei Moto's vulcanized foam has excellent tear strength, less sag 1), and excellent whiteness.

The tear strength of the vulcanized foam of the present invention is 1llll by the method described below.
Preferably 6.5 ki? f/in
above, more preferably 8 kgt/<n or above, and when measured by the method described later, preferably 15 kgt/<n or more.
% or less, more preferably 13% or less, and the above 11%
Products with excellent properties can be obtained in the surrounding area.

The vulcanized foam of the present invention is suitably used for waste materials (outer soles, inner soles, Mitsut9 soles, etc.), industrial products, cushioning materials, packaging materials, etc.Next, practical examples and comparative examples will be shown. The invention will be specifically explained. In Examples and Comparative Examples, 100 cm tensile stress (
Mloo), breaking strength (TB), and breaking elongation (gB) are determined according to JIS K6301, and tear strength is determined by AS.
Measurement was carried out in accordance with Tvl D 1564, except that the sample thickness was 101 m and the tensile speed was 50 cm/ml n. Hardness (US) was measured using a rubber tester tie fC (manufactured by Kobunshi Keiki, Sponge Hardness Kawa 1), and density was measured using a buoyancy method. Hetari weighs 20kl? A point cone (a disk with a larger base area than the sample) is placed at a height of 5
- 60X60X20 at 80 times/min.
% sponge sample was repeatedly struck 300,000 times and the permanent strain was measured.

To: Thickness of the sample before the test (%) T: After the test, the whiteness of the sponge was visually compared and evaluated. J.I.
RB820.

Vinyl bond content 92%, crystallinity 25%.

[η] Toluene-3oυ-1,25), polyisoprene rubber (manufactured by Nippon Gosei Co., Ltd., JSRlR2200) and styrene-butadiene rubber (manufactured by Nippon Gosei Rubber Co., Ltd.).

JSR1502) and its composition compound as shown in Table 60.
The mixture was mixed in a pressure kneader under pressure and vulcanized at 155° C. for 22 minutes to obtain a foam. The physical property results are shown in the table. The physical property results are shown in the table.

Actual row-3 1,2-FBI) (manufactured by Japan Synthetic Rubber, JS)
t RB830゜Vinyl bond metal 93%, crystallinity 2
9 rice cakes.

A foam was obtained in the same manner as in Example 1 using toluene [η] = 1.25) and its additive at 30°C in the mixing ratio shown in the table. The physical property results are shown in the table.

Practical Example-4 The same procedure as Practical Example 1 was carried out except that the use of the vulcanization accelerator and sulfur was changed. The physical property results are shown in the table.

It is clear from the results of Examples 1 to 4 that a foam with good tear strength and stiffness can be obtained at a commercial foaming ratio, but has a good texture when compared with the comparative series.

Comparison [Nri-1 3 parts by weight of the vulcanization accelerator TMTD beyond the scope of the present invention,
A foam was obtained in the same manner as in Example Rely 1, except that 1.5 parts by weight of the vulcanization accelerator BBS was used. This foam exhibits a large degree of dense expansion, making it impossible to obtain a highly foamed product.

Comparative Example-2 Except for using 0.6 parts by weight of sulfur, which exceeds the range of the present invention,
A foam was obtained in the same manner as Example M-1. This foam has a high density, making it impossible to obtain a highly foamed product, and the whiteness of the sponge is also poor.

Comparative Example-3 Vulcanization accelerator TMTD in 1.5-layer plate part, vulcanization accelerator BBS
A foam was obtained in the same manner as in Practical-1 with 0.75 subkL parts and sulfur added at a level different from that of the present invention. This foam has a large sag.

Comparison N-4 MBTS, a vulcanization accelerator commonly used for sponge rubber for this purpose, was used in 1.2 mold parts, MBT, which is a general rule for vulcanization, was used in 02 layers, and sulfur was added in 1.2 layers. The others used are implementation row-1.
A foam was obtained in the same manner. This foam has poor tear retention and poor whiteness.

Claims (1)

[Claims] (1)■ 1.2-polybutadiene with a vinyl bond content of 70% or more, a crystallinity of 5% or more, and an intrinsic viscosity [η] (measured in toluene at 30°C) of 0.5 di/i or more 30 to 100i31%, and (B) 0 to 70% by weight of one or more selected from natural rubber, diene-based synthetic rubber, and block copolymers of aromatic vinyl compounds and conjugated diene compounds. For 100 parts by weight of the mixture [(4)+(B)), (Q thiuram vulcanization accelerator 0.6 to 2.5 parts, sulfur 0.05 to 0.5 parts), and ( A vulcanized foam characterized by containing a blowing agent.