KR960008114B1 - Rubber composition - Google Patents

Abstract

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Description

Rubber composition

1 is a cross-sectional view of a test composite sheet structure having certain rubber compositions laminated to peroxide-vulcanized hydrogenated NBR rubber; And

2 and 3 show a different test structure similar to that of FIG. 1 but with rubber compositions laminated with brass and nylon, respectively.

* Explanation of symbols for main parts of the drawings

10: sheet of composition A 20: sheet of composition B

30: cellophane flap 40: brass plate

50: nylon fabric

The present invention relates to rubber compositions which are particularly suitable for bonding to hydrogenated rubber and also metals and fiber materials.

Generally, rubber products, including tires, belts, molded articles, rubber rolls, hoses, and the like, are exposed to elevated temperatures and high loads when applied to vehicles, construction equipment, or hydraulic systems. Therefore, these rubber products must be highly resistant to heat and oil over extended periods of time.

Various rubbers have been proposed that are resistant to oils and high temperatures of 120 ° -150 ° C., and they are acrylonitrile-butadiene copolymer rubber (NBR), acrylic rubber (ACM), ethylene-acrylic copolymer rubber (AEM), ethylene- Acrylonitrile-butadiene copolymer rubbers with acryl-vinyl acetate terpolymer rubber (ER), chlorosulfonated polyethylene rubber (CSM), chlorinated polyethylene rubber (CM) and conjugated diene rearranged by hydrogenation (hydrogenated NBR ). These known high performance rubbers are used in many examples, especially in composite structures consisting of reinforcing metals and fibers such as brass.

Sulfur facilitates the adhesion of rubber to brass and fibers. However, at the time of sulfur-vulcanization, the high performance rubber does not show its heat resistance completely but shows deterioration. Non-sulfurized, with moderate heat resistance, is virtually unsatisfactory for adhesion to brass and fibers.

To improve both heat resistance and adhesion to metals and fibers, certain metal or fiber-adhesive intermediate rubbers are usually sandwiched between high performance rubbers and reinforcements. Among the above-mentioned high performance rubbers, the most heat resistant are hydrogenated NBR rubbers, but this requires vulcanization using organic peroxides. These vulcanized rubbers are effective for adhesion to peroxide vulcanized rubbers but not for brass or fibres. Sulfur-vulcanized rubbers are effective for brass and fiber, but induce contact interference vulcanization when in contact with peroxide vulcanized hydrogenated NBR rubber.

Hydrogenated NBR rubbers can be made of peroxide and sulfur to provide balanced heat resistance and adhesion. Compositions of this type are adhesive to a limited extent, involve an interfering reaction between the two systems of vulcanization and reduce the resistance of the vulcanized rubber to brittle fracture under external forces applied by dynamic vibration. Therefore, there has been an urgent need for improved rubber compositions that tend to be suitable hydrogenated NBR rubbers where they must be used with brass and fiber.

It has now been found that rubber compositions with good adhesion and modulus properties can be obtained using sulfur, organic peroxide and triazine compounds combined with sulfur-vulcanizable base rubbers.

The rubber compositions anticipated by the present invention consist essentially of organic peroxides that induce strong adhesion to hydrogenated NBR rubbers, triazine compounds that impart high adhesion to metals and fibers, and sulfur to provide improved modulus. . The composition is particularly suitable for use in tires, belts, molded articles, rubber rolls and hose products.

It is therefore a primary object of the present invention to provide new, improved rubber compositions which are excellent in adhesion to peroxide vulcanized hydrogenated NBR rubber and also to brass and fibers without involving interference vulcanization.

These and other objects and features of the present invention will be better understood from the following detailed description, which is written in connection with the accompanying drawings.

According to the invention, there is provided a composition comprising (a) sulfur-vulcanizable starting rubber; (b) 0.1-10 parts by weight of sulfur based on 100 parts by weight of starting rubber; (c) 0.2-15 parts by weight of organic peroxide based on 100 parts by weight of starting rubber; And (d) 0.2-15 parts by weight of a 6-R-2, 4-dimercapto-1, 3, 5-triazine compound of the following general formula based on 100 parts by weight of starting rubber.

Wherein R is a mercapto, alkoxy, mono- or di-alkylamino, mono- or di-cycloalkylamino, mono or di-arylamino or N-alkyl-N'-arylamino group

Suitable starting rubbers for the purposes of the present invention are sulphur-vulcanized natural and synthetic rubbers. Typical examples include natural rubber (NR), polyisoprene rubber (IR), styrene-butadiene copolymer rubber (SBR), polybutadiene rubber (BR), acrylonitrile-butadiene copolymer rubber (NBR), ethylene-propylene-diene Terpolymer rubber (EPDM) and the like.

Sulfur that can be used here includes, for example, particulate sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, sulfur chloride and the like.

The content of sulfur that can be added should be in the range of 0.1-10 parts by weight, preferably 0.2-5 parts by weight, based on 100 parts by weight of the starting rubber. An amount less than 0.1 part reduces the modulus and leads to an interference reaction with more than 10 parts peroxide vulcanized hydrogenated NBR rubber.

Suitable organic peroxides are those that allow for crosslinking to occur at a moderate temperature at curing temperatures. For this purpose, dialkyl peroxides having a half life of 10 hours and decomposition temperatures higher than 80 ° C. are preferred. Specific examples include dicumyl peroxide, 1, 3-bis- (t-butylpropoxyisopropyl) -benzene, 4-4'-di-tert-butylperoxy valeric acid n-butyl and the like .

The amount of organic peroxide that can be added should be in the range of 0.2-15 parts by weight, preferably 0.5-5 parts by weight based on 100 parts by weight of the starting rubber (calculated by net weight). An amount less than 0.2 parts does not give sufficient adhesion to peroxide-vulcanized hydrogenated NBR rubber. More than 15 parts will leave unconsumed peroxide, making vulcanized rubber less heat resistant.

Triazine compounds useful in the present invention are 6-R-2, 4-dimethylmercapto-1, 3, 5-triazine represented by the following general formula.

Wherein R is a mercapto, alkoxy, mono- or di-alkylamino, mono- or di-cycloalkylamino, mono- or di-diarylamino, or N-alkyl-N'-arylamino group. Particularly preferred is 2, 4, 6-trimercapto-1, 3, 5-triazine.

The amount of triazine compound that can be added should be in the range of 0.2-15 parts by weight, preferably 0.5-10 parts by weight, based on 100 parts by weight of the starting rubber. An amount less than 0.2 parts reduces the modulus and degrades adhesion to brass and fibers. More than 15 parts will not produce better results.

In addition, various additives such as vulcanization accelerators, antioxidants, weight agents, softeners, plasticizers, tackifiers, lubricants, annealing agents, colorants, foaming agents, vulcanizing agents, dispersants, processing aids and the like can be used.

The triazine compounds according to the invention help to act as accelerators in sulfur vulcanization. To obtain improved modulus of vulcanized rubbers, including, for example, aldehyde-ammonia, aldehyde-amine, guanidine, thiourea, thiazole, sulfenamide, thioram, dithiocarbamate, xanthogenate and the like. Independent promoters may be added as appropriate.

The rubber composition of the present invention allows strong adhesion to peroxide-vulcanized hydrogenated NBR rubber and also to brass and fibers. There are no particular restrictions imposed on the type of fiber, but for example polyhexamethylene adipamide (nylon-66), polycaprolactum (nylon-6), polyvinyl alcohol, polyethylene terephthalate (polyester), rayon, aromatic Organic fibers such as polyamide, aromatic polyester and the like. Especially preferred are such fibers treated with a mixture of resorcin-formalin condensate and latex.

The following examples further illustrate the invention. Unless stated otherwise, all units are in parts by weight.

Examples 1-17 and Comparative Examples 1-7

Hydrogenated NBR composition A was prepared by blending as shown in Table 1 and rolling on a mixing roller at 60 ° C. for 15 minutes. Other rubber compositions B were also prepared in the same way and the details of the formulations are shown in Tables 2-7.

All rubber compositions B were tested for adhesion to modulus and composition A at 100% elongation, adhesion to brass and adhesion to nylon under the conditions shown below and the results were tabulated.

1) Modulus

Each Composition B was rolled onto a laboratory roll to a thickness of 2.2-2.3 mm and then vulcanized to 30 kgf / cm ² for 90 minutes in a laboratory press at 153 ° C. After placing the vulcanized sheet at room temperature for 24 hours, the modulus was measured according to JIS K6301.

2) rubber-to-rubber adhesive

Composition A and Composition B were each rolled onto a laboratory roll to a thickness of 2.0 mm. As shown in FIG. 1, a test specimen was prepared by laminating Sheet 20 of Composition B to Sheet 10 of Composition A and the dimensions of the two sheets were 15 cm × 10 cm × 2.0 mm. Cellophane 30 was placed in the seam and at one end of the laminate with flaps to connect to the tensile tester. The laminates were press-vulcanized at 30 kgf / cm ² for 90 minutes on a laboratory press at 153 ° C. After 24 hours at room temperature, the resulting vulcanized rubber was cut to a width of 2.54 cm.

Peel strength was measured in a tensile tester at a pull speed of 50 mm / min as defined in JIS K6301.

3) Rubber-to-brass adhesive

Each composition B was rolled on a laboratory roll to a thickness of 2.5 mm. The test specimens shown in FIG. 2 consisted of Sheet 20 of Composition B laminated with brass plate 40, both dimensions 15 cm × 10 cm × 2.5 mm, and a cellophane flap 30 inserted therebetween. The laminates were press vulcanized at 30 kgf / cm ² for 90 minutes in a laboratory press at 153 ° C. to obtain vulcanized rubber and then placed at room temperature for 24 hours.

Peeling strength was determined by the method of said 2).

4) Rubber-to-fiber adhesive

Each composition B was rolled on a laboratory roll to a thickness of 2.5 mm. As shown in FIG. 3, the test specimens were both 15 cm × 10 cm × 2.5 cm in size, with the nylon fabric 50 composed of sheet 20 of laminated composition B and cellophane flap 30 inserted in the seam of the laminate. Nylon fabric 50 is a square fabric woven from nylon-66 fabric, immersed in a mixture of resorcin-formalin condensate and latex at 20 ° C. for 5 minutes, followed by drying at 140 ° C. for 5 minutes, and heat set at 200 ° C. for 3 minutes. (heat setting) made. The laminate was press vulcanized at 30 kgf / cm ² for 90 minutes at 153 ° C. After 24 hours at room temperature, the vulcanized rubber was cut to a width of 2.54 cm.

Peeling strength was determined by the method of said 2).

In Table 2-7, the adhesion was evaluated as follows;

1) rubber-to-rubber adhesive

Adhesive strength kgf / 2.54cm

Adhesive appearance

◎ High peel strength at crushing

○ Low peel strength at crushing

△ High peel strength at interfacial peeling

× Low peel strength at interfacial peeling

2) rubber-to-brass adhesive

○ excellent rubber covering area

× poor rubber covering area

3) rubber-to-fiber adhesion

○ excellent rubber covering area

× poor rubber covering area

Comparative Example 1, a control vulcanized only with sulfur, is unacceptable in rubber-to-rubber-adhesion, as can be seen from Table 2. The peroxide-vulcanized control, Comparative Example 2, showed inadequate adhesion to brass and nylon.

As is apparent from Table 3, Examples 1 and 2 expressing the present invention are very satisfactory in terms of adhesion to all the materials tested. Comparative Example 3 without triazine shows reduced modulus, resulting in poor adhesion to brass and nylon.

Table 4 demonstrates that Examples 4-6 using different accelerators impart improved adhesion to rubber, brass and nylon, which means that the compositions of the present invention can select a wide range of accelerators.

The use of triazines beyond the ranges specified above does not impart acceptable adhesion to brass and nylon as demonstrated by Comparative Example 4.

As is clear from Tables 6 and 7, the greater the adhesion to rubber, the higher the peroxide content that can be added. Sulfur added in higher amounts is effective in obtaining higher modulus. Comparative Example 5, using small amounts of sulfur and peroxide, results in insufficient modulus resulting in unacceptable adhesion to rubber, brass and nylon.

It will be apparent to those skilled in the art that various changes and modifications can be made to the present invention without departing from the scope of the appended claims.

1) SRF, Ashhize, No. 50, Asahi Carbon Company

2) Vulkanox DDA, diphenylamine derivatives, Bayer AG

3) Vulkanox ZMB-2, 4, 5-methylmercapto-benzimidazole zinc salt, Bayer AG

4) Wax, RE 520, Hochester AG

5) Teic, triallyl isocyanate, Nakine Chemical Company

6) Witamol 218, trimellitic acid ester, dynamite novel AG

7) Percadox 14/40, 1, 3-bis- (t-butylperoxy-isopropyl) -benzene, peroxide content 40% by weight, Kaka Yunouri Co., Ltd.

8) Nipol 1042, NBR, Nippon Xeon Company

9) OD-3, Nonflex OD-3, Seiko Chemical Company

10) Accelerator TS (tetramethylthiuram monosulfide), Sunseller TS-G, Sanshin Chemical Company

1) and 7): same as in Table 1.

11) Nipole 1502, SBR, Nippon Xeon Company

12) zisnet F, 2, 4, 6-trimercapto-1, 3, 5-triazine, sanko chemical company

1), 7), 8) and 9): same as in Table 1 and 2.

13) Accelerator NOBS (N-oxydiethylene-2-benzothiazole sulfamide), Sunseller 232-MG, Sanxin Chemical Company

14) Accelerator CZ (Cyclohexyl-benzothiazyl-sulfenamide), Sunseller CM-PO, Sanxin Chemical Company

15) Accelerator DM (Dibenzothiazyl Disulfide), Sunseller DM-PO, Sanshin Chemical Company

1), 7), 8), 9), 10) and 12) are shown in Table 1-3.

1), 7), 8), 9) and 12) as shown in Table 1-3.

1), 7), 8), 9), 10) and 12): same as in table 1-3

1), 7), 8), 9) 10) and 12): same as in table 1-3

Claims (5)

A rubber composition comprising the following (a)-(d): (a) sulfur-vulcanizable starting rubber; (b) 0.1-10 parts by weight of sulfur based on 100 parts by weight of the starting rubber; (c) 0.2-15 parts by weight of organic peroxide based on 100 parts by weight of the starting rubber; And (d) 0.2-15 parts by weight of 6-R-2, 4-dimercapto-1, 3, and 5-triazine compound of the following general formula, based on 100 parts by weight of the starting rubber.

Wherein R is a mercapto, alkoxy, mono- or di-alkylamino, mono- or di-cycloalkylamino, mono- or di-arylamino, or N-alkyl-N'-arylamino group. The rubber composition according to claim 1, wherein the starting rubber is natural rubber, polyisoprene rubber, styrene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber or ethylene-propylene-diene terpolymer rubber. The rubber composition of claim 1, wherein the sulfur is particulate sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, dispersible sulfur or sulfur chloride. The method of claim 1, wherein the organic peroxide is dicumyl peroxide, 1, 3-bis- (t-butylperoxy-isopropyl) benzene or 4, 4'-di-tert-butylperoxy valeric acid n-butyl Phosphorus rubber composition. The rubber composition according to claim 1, wherein the triazine compound is 2, 4, 6-trimercapto-1, 3, 5-triazine.

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