JPS60163944A - Rubber composition - Google Patents

Abstract

PURPOSE:A rubber composition having excellent elasticity, flexibility, wear resistance, adhesiveness, cold-temperature resistance, heat resistance, moldability, processability, foaming characteristics, and color, made by compounding a specified block copolymer, a rubber-like polymer, a vulcanizing agent, a foaming agent, and a filler. CONSTITUTION:90-10wt% block copolymer, made from 25-95wt% vinyl aromatic compound (a) containing 5-25wt% vinyl aromatic compound consisting of a chain of 1-4 monomer units, and a conjugated diene (b), shown by formula I or II (where A is the vinyl aromatic compound polymer block, the amount of A in total being 50-97wt% of component a in total; B is the copolymer of components b and a, having 2-10 tapered blocks with increasing component a; n is 3-6; x is the coupling agent residue); and 10-90wt% rubber-like polymer are compounded. Then, 100pts.wt. compound above, 0.1-10pts.wt. vulcanizing agent, 0-30pts.wt. foaming agent, and 0-100pts.wt. filler are compounded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides moldability, processability, foamability, flexibility, abrasion resistance,
For further details regarding the rubber composition that has excellent adhesion and color tone and has a good balance of various physical properties including these, please refer to (al
A -B -A or (A-B)% It is a copolymer of a conjugated diene and a vinyl aromatic compound, and the B part consists of 2 to 10 tapered blocks in which the vinyl aromatic compound gradually increases.The outside is an integer from 3 to 6, and X is the coupling agent. block copolymers (hereinafter simply referred to as block copolymers) in which the amount of chains of 1 to 4 vinyl aromatic compounds in monomer units is 5 to 25% by weight of the total vinyl aromatic compound content. (sometimes abbreviated as “combination”)
, (b) Isoprene rubber (IR), natural rubber (NJ, acrylonitrile-butadiene rubber (NBR,), styrene-butadiene rubber (SBJ, ethylene-propylene rubber (EPR), high styrene rubber (H8J, butadiene rubber (BJ, ■) 2 polybutadiene rubber (1,2PB
D ), butyl rubber (IIJ), chloroprene rubber (CR
) at least one rubber, (C) a vulcanizing agent, an FD1 foaming agent, and (e) a filler, which is highly elastic, flexible, and has abrasion resistance, adhesiveness, cold resistance, heat resistance, and slip resistance; This invention relates to an easily foamable rubber composition that has excellent moldability and processability.

BACKGROUND ART Composite vulcanizates of rubber and styrene-butadiene block copolymers having rubber elasticity have traditionally been used in footwear, industrial parts, and automobile interior materials, taking advantage of their moderate physical strength properties.

However, recently, there has been an increasing demand for rubber compositions that have excellent properties such as flexibility and abrasion resistance, as well as good adhesion, color tone, and heat and cold resistance, with a good balance of physical properties, both in terms of feel and practicality. It's being cut.

Conventional composite vulcanizates of styrene-butadiene block copolymers and rubber have problems in abrasion resistance and do not meet the above requirements.

The present inventors aimed to obtain a rubber composition that has particularly excellent properties such as flexibility and abrasion resistance, and also has a good balance of physical properties and has excellent adhesion, color tone, and slip resistance. As a result of research, we have arrived at the present invention. That is, the present invention comprises (a) a mixture consisting of 90 to 10% by weight of an Al block copolymer (10 to 90% by weight of at least one type of BL rubbery polymer (a) + (C to 10 parts by weight of BL) a crosslinking agent 0 .1 to 10 parts by weight f blowing agent 0 to 30 parts by weight t filler may be contained as necessary.

The block copolymer (al component) of the composition of the present invention is
A vinyl aromatic compound-conjugated diene block copolymer with a vinyl aromatic compound content of 25 to 95% by weight obtained by polymerization using an organolithium compound as an initiator in a hydrocarbon solvent, and the copolymer has the general formula A-B-A switch (A
-B), (The B part consists of 2 to 10 tapered blocks in which the vinyl aromatic compound gradually increases. n is an integer of 3 to 6, and X is the residue of a coupling agent.)
and the amount of vinyl aromatic compound chains consisting of 1 to 4 monomer units is 5% of the total vinyl aromatic compound content.
~25% by weight block copolymer. The block copolymer has a vinyl aromatic compound content of 25 to 95% by weight, preferably 28 to 70% by weight. If the vinyl aromatic compound is less than 25% by weight, the abrasion strength and tensile strength will be poor;
If it exceeds the weight limit, the elongation will be poor.

The characteristics of the block copolymer which is component (a) of the present invention are as follows:
General formula A-B-A combination (A-B), X (n is 3 to 6
, X is a residue of a coupling agent), the B portion contains a vinyl aromatic compound in a specific range, and further has a tapered block number in a specific range, and the block copolymer has a vinyl aromatic compound in a specific range. It is a copolymer with a chain distribution of compounds. Due to these characteristics, wear strength,
The balance between tensile strength and elongation is significantly improved.

The rubbery polymer that is the component (b) of the composition of the present invention is natural rubber or diene-based synthetic rubber, and the addition of these rubbers can improve the hardness adjustment and physical property balance of the crosslinked product of the composition of the present invention. can. I] 15, NJ NBR,, SBR,
EPR, EPDM, NBR,.

Examples include BR, 1,2PBD, IIR, and CR. Among these, preferred rubbers are NRlIJ NBJ SB
R,,1,2PBD, etc., and these provide favorable crosslinking properties as well as hardness adjustment.

(The blending amounts of (al and (bl) are based on the weight ratio (a)/(b) = 9
0-10/10-90, preferably 80-207
It is 20-80. If the amount of ta) exceeds 900 parts by weight, the crosslinking property will be impaired, and if it is less than 10 parts by weight, the abrasion strength and tensile strength will decrease significantly.

The crosslinking agents (C) used in the present invention are di-t-butylperoxy 3,3.5-trimethylcyclohexane, dicumyl peroxide, n-butyl-4,4-bis-t-
Butylperoxyvalerate, αtα'-di-t-butylperoxy-di-p-diisopropylbenzene, 2,5
-dimethyl-2°5-di(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, and sulfur. The amount of crosslinking agent is (
It is 0.1 to 10 parts by weight, preferably 0.1 to 5 parts by weight, per 100 parts by weight of a)+1b). (When using sulfur as a crosslinking agent, guanidines, thiazoles,
It is preferable to add 0.1 to 5 parts by weight of a vulcanization accelerator such as thiurams to 100 parts by weight of (a) + (b). )
If the amount of the crosslinking agent is less than 0.1 part by weight, the crosslinking time will be longer or the crosslinking property will be significantly impaired, and if it exceeds 10 parts by weight, the appropriate crosslinking width will be extremely narrow, making it impossible to obtain a stable product. do not have.

Known inorganic or organic blowing agents can be used as the Tdl component. Specific examples of blowing agents include sodium bicarbonate, ammonium bicarbonate, sodium carbonate, ammonium carbonate, azodicarbonamide (ADC), dinitrone pentamethylenetetramine (DNPT), dinitrosoterephthalamide, azobisisobutyronitrile. ,
Examples include barium azodicarboxylate, sulfonyl hydrazide, toluenesulfonyl hydrazide, and the like. These foaming agents may be used in combination with known foaming aids such as urea and urea derivatives. The amount of blowing agent used is based on the mixture (al
The amount is 0 to 30 parts by weight per 100 parts by weight of +(bl), but preferably 0.1 to 15 parts by weight from the viewpoint of appearance and texture.

(As the e+ acid component, known inorganic or organic fillers can be used. Examples of fillers include carbon black, calcium carbonate, silica fillers, magnesium carbonate, clay, etc.) The amount used is 0 to 100 parts by weight per 100 parts by weight of the mixture (al-11b+).
Parts by weight.

In the composition of the present invention, other compounding agents that are blended in general rubber compositions, such as vulcanization accelerators, anti-aging agents, processing aids, softeners (oils), etc. may be added as appropriate. do not have.

The method of mixing the compound in the present invention is not particularly limited and may be any mixing method used for general rubber compounds such as a Banbury type mixer, pressure kneader, open roll, etc.
Preferably, mixing is carried out at a temperature in the range from 0 to 120°C. The mixture thus obtained was fed into a mold and heated under pressure for 130 minutes.
It can be processed in a temperature range of -180°C, preferably 140-170°C. In the case of a foaming system, the compound is crosslinked and the foaming agent is decomposed by heating to a temperature higher than the decomposition temperature of the foaming agent. The mold clamping pressure must be such that it substantially suppresses the expansion of gas generated by decomposition of the blowing agent, and is usually carried out at a pressure of 80 Kq/cnlc or more.

The rubber composition of the present invention has excellent flexibility and abrasion resistance, and has well-balanced physical properties and excellent adhesion, color tone, and slip resistance.

The rubber composition of the present invention is suitably used for industrial goods, automobile parts, footwear materials (outsoles, midsoles, innersoles, crepe sponges), cushioning materials, packaging materials, and the like.

Next, the present invention will be specifically explained with reference to Examples and Comparative Examples, but the present invention is not limited as long as it does not go beyond the gist of the present invention.

In Examples and Comparative Examples, hardness and tensile strength are determined according to JISI (
-Compliant with 6301. Amount of wear: DIN method is based on German industrial standard Nn53516, AKRON method is based on B5-903, adhesive strength is expressed as peel strength using No-tape industrial adhesive ≠ 960 (contains Desmodur 3V) (Sample 2) , 54 cm Radius width tanzak tensile speed: 50
ran). The color tone is determined visually (white, colorless ◎~×yellow, solid color). The slip property was measured on wet ceramic tiles using a Stancie wet skid machine. ) R, B820 is 1.2 PB made by Japan Synthetic Rubber
D (crystallinity: 24.5 MI = 3), and SBR was a bonded styrene 48 product manufactured by Showa Denko.

Production Example (A-B-A) Production method of type block copolymer a-1 After charging cyclohexane 50002 and tetrahydrofuran 1f in a washed and dried stirrer and jacketed autoclave under a nitrogen atmosphere, the internal temperature was raised to 70°C. I made it.

Next, a hexane solution containing 0.64 f of n-butyllithium was added, followed by 300 l of styrene, and polymerization was carried out for 60 minutes.

The polymerization conversion rate of styrene was 100%. Then a mixture of styrene 502 and butadiene 1252 was added to 6
Polymerization took place for 0 minutes.

The polymerization conversion rate of styrene and butadiene was 100%. Repeat this operation twice more. Then add butadiene to 1
257 was added and the polymerization was carried out to a polymerization conversion rate of 100. After this, 3,007 g of styrene was further added and polymerized for 60 minutes.

The conversion rate was 100.

During the polymerization, the temperature was always adjusted to 70°C. After completion of polymerization, add 2,6-tert-butyl to the polymer solution.
After adding p-cresol, cyclohexane was removed by heating to obtain block copolymer a-1.

The molecular properties of a-1 are shown in Table 1.

(A-B), Method for producing X-type block copolymer a-2 After charging cyclohexane 60002 and tetrahydrofuran 12 in a washed and dried stirrer and jacketed autoclave under a nitrogen atmosphere, the internal temperature was raised to 50°C. .

Next, a hexane solution containing 2.5% of n-butyllithium was added, and then 380% of styrene was added and polymerized for 60 minutes.

The polymerization conversion rate of styrene was 100%.

Next, a mixture of styrene 102 and butadiene 3002 was added and polymerized for 60 minutes. The polymerization conversion rate of styrene and butadiene was 100%. This operation was repeated once more. Next, 10 g of butadiene was added and polymerization was carried out to a polymerization conversion rate of 100.

Next, 1.72 g of tetrachlorosilane was added as a hexane solution, and a coupling reaction was carried out for 20 minutes.

During the polymerization, the temperature was always controlled at 50°C. Next, add 2,6-di-tert-butyl-p to the polymer solution.
-Cresol was added and cyclohexane was removed by heating to obtain block copolymers a and -2.

Molecular properties are shown in Table 1.

(Left below) Method for producing styrene-butadiene block copolymer a-3 (block copolymer outside the scope of the present invention) Cyclohexane 50002 and tetrahydrofuran 1fi+ were charged in a washed and dried stirrer and jacketed autoclave under a nitrogen atmosphere. After that, the internal temperature was brought to 70°C.

Next, a hexane solution containing 0.64.9% of n-butyllithium was added, and then 7502% of styrene was added and polymerized for 120 minutes. The polymerization conversion rate of styrene was 100%.

Then, butadiene 5002 was added to increase the polymerization conversion rate to 100.
Polymerization was carried out up to the point in time.

During the polymerization, the temperature was always adjusted to 70°C.

After the polymerization was completed, 2,6-di-tert-butyl-p-cresol was added to the polymer solution, and then cyclohexane was removed by heating to obtain block copolymer a-3.

a-31d It is a block copolymer of styrene and butadiene with a bound styrene content of 60 parts and does not have a tapered block.

Examples L2, 3, Comparative Examples 1, 2.3 The compositions shown in Table 2 were obtained by mixing the listed components using a pressurized knee gun and vulcanizing the mixture at 160° C. for 15 minutes. Test pieces were prepared for each and various physical properties were measured.1 - The results are shown in Table 2.

It can be seen from Table 2 that composition Example 1.2.3 of the present invention has superior wear resistance compared to Comparative Examples 1 and 2.3. Although the composition of the present invention exhibits hardness and tensile strength similar to those of the comparative example, it has excellent abrasion resistance, indicating that it is a material characterized by abrasion resistance.

(Left below) Examples 4 and 5. Comparative Examples 4, 5.6 The compositions shown in Table 3 were obtained by mixing the listed components using a pressurized knee gun and vulcanizing the mixture at 160° C. for 15 minutes.

Inventive compositions Examples 4 and 5 have superior performance compared to the compositions of Comparative Examples 4 and 5.6, which are outside the scope of the inventive blend composition. In other words, the comparative example lacks flexibility and has inferior abrasion resistance.

(Left below) Examples 6, 7, 8.9 The compositions shown in Table 4 except for Example 9 were prepared in the same manner as in Table 3.

Examples 6, 7, and 8 are finely foamed sponges that are flexible, have excellent abrasion resistance, and have a good color tone. These are found to be suitable for footwear applications, such as crepe sponge materials.

Example 9 provides a lightweight sponge and is suitable for footwear applications, such as midsole sponge material.

(Left below) Example 10, ]1, 12, 13, Comparative Example 7,
8 The compositions shown in Table 5 were obtained in the same manner as in Table 3.

Example 10. II and 12 show superior performance compared to the composition of the comparative example, which is outside the scope of the present invention. In other words, the comparative example has a defect with poor wear resistance.

In comparison with the composition of Comparative Example 8, which is outside the scope of the present invention, the composition of Example 13 exhibits superior performance in abrasion resistance, fluidity, and surface texture.

(Margin below) Ref+7

Claims (1)

[Scope of Claims] A mixture (a) consisting of (al vinyl aromatic compound-conjugated diene block copolymer 90 to 10 weight percent and at least one of (bl rubbery polymers 10 to 90 weight percent)
fcl vulcanizing agent 0.1 to bl 1o o parts by weight
A rubber composition comprising 10 parts by weight (0 to 30 parts by weight of a d1 blowing agent!6 + 0 to 100 parts by weight of a filler), wherein the block copolymer (al is 25 parts by weight of a vinyl aromatic compound)
~95 weight ratio included, general formula A-B-A or (A-B)
, 1 It is a combination, and has 2 to 10 tapered blocks in which the vinyl aromatic compound gradually increases in the B part, and n is 3 to 6.
(X is a residue of a coupling agent), and the content of the vinyl aromatic compound constituting a chain of 1 to 4 monomer units is 5 to 25% by weight of the entire vinyl aromatic compound. A rubber composition characterized by: