JPH04227946A - Rubber composition - Google Patents

Abstract

PURPOSE:To develop a chlorinated polyethylene rubber composition which can easily exhibit a high modulus, excels in bondability by vulcanization with a metal such as brass, and has a relatively simple compounding recipe. CONSTITUTION:A rubber composition comprising 100 pts.wt. chlorinated polyethylene rubber and/or maleic anhydride-modified chlorinated polyethylene rubber, 0.5-5 pts.wt. dicyclohexylamine salt of 2-mercaptobenzothiazole (MDCA), 0.2-10 pts.wt. trithiocyanuric acid, and 0.05-5 pts.wt. sulfur, wherein the contents of MDCA, trithiocyanuric acid and sulfur satisfy the following formulas (I) and (II): MDCA (phr) X trithiocyanuric acid (phr) >=0.5...(I) sulfur (phr)/MDCA (phr) >=0.1...(II).

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a chlorinated polyethylene rubber-based rubber that has excellent vulcanization adhesion to brass and is useful for rubber/metal composite products used in fields that require heat resistance and oil resistance. The present invention relates to a composition, and particularly to a rubber composition suitable for use as an intermediate rubber between the inner tube rubber, outer tube rubber, and pressure-resistant reinforcing steel wire layer of a heat-resistant high-pressure hose having a brass-plated pressure-resistant reinforcing steel wire layer.

0002

[Prior Art] Recently, tires, belts, molded products, rolls,
Many rubber products, such as hoses, are used for long periods of time with heated oil under high temperature and pressure, and the deterioration of rubber products under such conditions is always a serious problem. This is because if the rubber product deteriorates significantly, a great deal of time and effort is required for maintenance and replacement, and furthermore, the deterioration of the rubber product may cause a major accident. Excellent oil resistance
Acrylonitrile is a polymer that can withstand continuous use under such a high temperature (120 to 150°C) environment.
Butadiene copolymer rubber (NBR), acrylic rubber (AC
M), ethylene-acrylic rubber (AEM), ethylene-
The conjugated diene moiety of acrylonitrile copolymer rubbers such as acrylic-vinyl acetate copolymer rubber (ER), chlorosulfonated polyethylene rubber (CSM), chlorinated polyethylene rubber (CM), and acrylonitrile-butadiene copolymer rubber (NBR) Hydrogenated rubber and the like are known. Among these polymers, chlorinated polyethylene rubber is a rubber with an excellent balance of various properties such as heat aging resistance, weather resistance, oil resistance, and chemical resistance. By the way, chlorinated polyethylene rubber does not contain double bonds in its main chain, so it cannot be vulcanized with normal sulfur, and is generally vulcanized with organic peroxides, thioureas, diamines, and trithiocyanuric acid. A sulfurizing agent is used. However, in general,
Vulcanizates made from thioureas and diamines have low modulus, and vulcanizates made from organic peroxides and trithiocyanuric acid have good modulus but have poor vulcanization adhesion to metals such as brass. However, the scope of industrial use of chlorinated polyethylene rubber compositions has been extremely limited. Therefore, the present applicant has developed a chlorinated polyethylene rubber composition that has high modulus and excellent vulcanization adhesion to metals such as brass. A rubber composition containing a vulcanization system containing diallyl phthalate, trithiocyanuric acid, and an organic peroxide as essential components was proposed (Japanese Patent Publication No. 61-26820). However, since this rubber composition has six types of essential components as a vulcanization system, there is little freedom in formulating the formulation, and the various properties have not been improved compared to the past. However, it was not completely satisfactory.

0003

[Problems to be Solved by the Invention] As mentioned above, it is a chlorinated polyethylene rubber composition, which has a high modulus of vulcanizate, and has excellent vulcanization adhesion to metals such as brass.
In addition, there is no known compound with a high degree of freedom in formulation. The present invention was made in view of the above facts, and it is possible to easily develop a high modulus, have excellent vulcanization adhesion to metals such as brass, and chlorinate a relatively simple formulation. The purpose of the present invention is to provide a polyethylene rubber composition.

0004

[Means for Solving the Problems] The present invention provides 2-
Dicyclohexylamine salt of mercaptobenzothiazole (abbreviation: MDCA) (C) 0.5 to 5 parts by weight, trithiocyanuric acid (D) 0.2 to 10 parts by weight, and sulfur (E
) 0.05 to 5 parts by weight, and MDCA (C)
, trithiocyanuric acid (D), and sulfur (E), the rubber composition is characterized in that it satisfies the following formulas (I) and (II) at the same time. (MDCA (phr) ) × (trithiocyanuric acid (phr) ) ≧ 0.5 ... (I) Sulfur (phr)
/MDCA(phr) ≧0.1
...(II)

[0005] The present invention will be explained in detail below. The polymer of the rubber composition of the present invention is chlorinated polyethylene rubber (A) and/or maleic anhydride modified chlorinated polyethylene rubber (B).

[0006] As the chlorinated polyethylene rubber (A),
Various grades are known that differ in their molecular weight, chlorine content, distribution of combined chlorine, etc. In the present invention, any grade of chlorinated polyethylene rubber may be used.

[0007] The maleic anhydride-modified chlorinated polyethylene rubber (B) is a mixture of chlorinated polyethylene rubber and maleic anhydride produced by reacting the chlorinated polyethylene rubber (A) with maleic anhydride during kneading. It is polymerized.

When maleic anhydride-modified chlorinated polyethylene rubber (B) is used, the crosslinking efficiency increases due to the effect of the group consisting of dicarboxylic acid and/or its anhydride, and therefore there is greater freedom in formulating the formulation. is improved, which is preferable.

Commercially available products corresponding to the maleic anhydride-modified chlorinated polyethylene rubber (B) include Elastrene Super (Showa Denko KK).

In the present invention, either one of the chlorinated polyethylene rubber (A) and the maleic anhydride-modified chlorinated polyethylene rubber (B) may be used, or both may be used in combination.

The component in the rubber composition of the present invention that contributes to vulcanization is the dicyclohexylamine salt of 2-mercaptobenzothiazole, which is an organic sulfur-containing compound.
C) and trithiocyanuric acid (D).

The dicyclohexylamine salt (C) of 2-mercaptobenzothiazole is abbreviated as MDCA and is a compound represented by the following chemical formula 1.

[0013]

[Chemical formula 1]

[0014] The present inventors initially thought that this compound was N,N-dicyclohexyl-benzothiazylsulfenamide represented by the following chemical formula 2, in which a sulfur atom and a nitrogen atom were covalently bonded. However, subsequent research revealed that it is a compound in which sulfur and nitrogen atoms form a salt through ionic bonding.

[0015]

[Case 2]

Further, trithiocyanuric acid (D) is represented by the following chemical formula 3, and is 2,4,6-trimercapto-1,
It is a compound also called 3,5-triazine.

[0017]

[Chemical formula 3]

In the present invention, trithiocyanuric acid (D) serves as a vulcanizing agent, and MDCA (C) serves as a vulcanization accelerator, contributing synergistically.

Sulfur (E) contained in the rubber composition of the present invention
) contributes to improving the vulcanization adhesion of this rubber composition to metals such as brass.

In the present invention, sulfur commonly used as a vulcanizing agent for rubber, such as powdered sulfur, highly dispersed sulfur, and insoluble sulfur, is used.

[0021] Although the details will be shown in Examples below, in the present invention, a sulfur donor cannot be used in place of sulfur (E).

The rubber composition of the present invention comprises the above components (A) to
It contains (E), and its content ratio is as follows.

MDCA (C) is used in an amount of 0.5 to 100 parts by weight of the chlorinated polyethylene rubber (A) and/or maleic anhydride-modified chlorinated polyethylene rubber (B).
5 parts by weight. If it is less than 0.5 parts by weight, vulcanization will not be performed sufficiently and no modulus will be developed;
If it exceeds 5 parts by weight, the vulcanization adhesion to metals such as brass and the heat resistance of the vulcanized rubber will deteriorate, which is not preferable.

Trithiocyanuric acid (D) is used in an amount of 0.2 to 10 parts by weight based on 100 parts by weight of the chlorinated polyethylene rubber (A) and/or maleic anhydride-modified chlorinated polyethylene rubber (B). If it is less than 0.2 parts by weight, vulcanization will not be carried out sufficiently and the modulus will not be developed, while if it exceeds 10 parts by weight, no further improvement in the modulus of the vulcanized rubber can be expected. This is undesirable because it reduces heat resistance and lacks vulcanization adhesion to metals such as brass.

Sulfur (E) is contained in an amount of 0.05 to 5 parts by weight per 100 parts by weight of the chlorinated polyethylene rubber (A) and/or maleic anhydride modified chlorinated polyethylene rubber (B).
Parts by weight. If it is less than 0.05 parts by weight, vulcanization adhesion with brass will be insufficient and vulcanization will be insufficient, while if it exceeds 5 parts by weight, further vulcanization with metals such as brass will be difficult. This is not preferred because not only is no improvement in adhesion expected, but the modulus and heat resistance of the vulcanized rubber are reduced.

Furthermore, components (C), (D) and (E)
The content ratio must satisfy the following formulas (I) and (II) at the same time. (MDCA (phr)
))×(trithiocyanuric acid (phr))≧0.5
...(I) Sulfur (phr) /MDCA (phr)
≧0.1 ...(II)

[0027] Furthermore, formula (I),
The unit of each component in (II) "phr" represents parts by weight based on 100 parts by weight of the polymer (in this specification, chlorinated polyethylene rubber (A) and/or maleic anhydride-modified chlorinated polyethylene rubber (B)).

Here, formula (I) is a requirement regarding the modulus, and MDCA (C) and trithiocyanuric acid (D
) does not satisfy formula (I), the desired modulus cannot be obtained.

This defines the minimum amount necessary for trithiocyanuric acid (D) to function effectively as a vulcanizing agent and MDCA (C) as a vulcanization accelerator.

[0030] Formula (II) is a requirement regarding vulcanization adhesion to brass, and if the amounts of sulfur (E) and MDCA (C) do not satisfy formula (II), desired adhesiveness cannot be obtained. I can't.

[0031] This is trithiocyanuric acid (D) and MD
This specifies the minimum amount of sulfur that can affect the vulcanization accelerating effect of MDCA (C) in the reaction with CA (C).

[0032] The essential components and their content ratios of the rubber composition of the present invention have been described above, but if necessary, commonly used acid acceptors such as magnesia, fillers, and reinforcing agents may be added to this rubber composition. , plasticizers, anti-aging agents, processing aids, and other additives may be mixed and kneaded.

The rubber composition of the present invention can be used for tires, belts,
It can be applied to many rubber products such as molds, rolls, and hoses that are used for long periods in high temperature and high pressure environments and require oil resistance.

Since the rubber composition of the present invention has excellent adhesion to brass, it is useful in the field of products that are vulcanized and integrated with brass bodies.

[0035] Here, the brass body is used as a reinforcing material in ordinary rubber products, and refers to wire rods, pipe materials, plate materials, steel materials, etc., and may be brass-plated.

In particular, the rubber composition of the present invention is suitable as an intermediate rubber used between the inner tube rubber, outer tube rubber, and pressure-resistant reinforcing steel wire layer of a heat-resistant high-pressure hose having a brass-plated pressure-resistant reinforcing steel wire layer. It is.

[0037] The vulcanization method may be a commonly used method,
Vulcanization may be performed at a temperature of about 130 to 200° C. by press vulcanization, steam vulcanization, hot water vulcanization, or the like.

[0038]

【Example】

The present invention will be specifically explained below based on examples.

First, the method of the performance evaluation test conducted here will be described. 1. Measurement of elastic modulus (100% modulus) A rubber composition was prepared, mixed for 15 minutes at 60°C using a mixing roll, and then mixed using a small laboratory roll.
The sheet was produced to a thickness of 0 mm. This sheet-like rubber was pressure-vulcanized at 165° C. for 30 minutes at a surface pressure of 30 kgf/cm 2 using a laboratory press molding machine. This is JIS
Using a tensile tester specified in K6301, it was pulled at a tensile speed of 500 mm/min, and the 100% modulus was measured and calculated. All measurement methods and calculations are in accordance with JIS K6301 3. The tensile test was conducted in accordance with the method described in the section.

2. Test for vulcanization adhesion to brass A rubber composition was prepared and mixed at 60° C. for 15 minutes using a mixing roll, and then formed into a sheet with a thickness of 2.5 mm using a small laboratory roll. And, as shown in Figure 1, 2.5
A sheet of rubber 1 with a thickness of mm was pressed onto a brass plate 2. However, cellophane paper 3 was placed on the part to be gripped by the chuck during peeling to prevent the upper and lower layers from adhering. this,
Using a laboratory press molding machine, at 165℃ for 30 minutes, surface pressure 3
It was pressurized and vulcanized at 0 kgf/cm2 and molded into one piece. After leaving it at room temperature for 24 hours, the molded and integrated sample was heated to 2.5
It was cut out to a width of 4 cm and subjected to an adhesion test. The peel force was measured in accordance with the method described in JIS K6301 8.3 Test for peeling rubber adhered to a metal piece in a 90 degree direction, using a tensile tester specified in JIS K6301 at a tensile speed of 50 mm. /min.

(Example 1) Regarding the effectiveness of sulfur, the above-mentioned performance evaluation test was conducted using the rubber composition shown in Table A. The results are shown in Table A. As is clear from Table A, regarding the elastic modulus (100% modulus) of vulcanized rubber, sulfur-free systems (Comparative Examples 1 and 8) and sulfur-containing systems (Inventive Examples 1 and 2)
, sulfur donor blend system (Comparative Examples 2-7 and Comparative Examples 9-1
4) were all at almost the same level. However, as is clear from Table A, only the sulfur-containing systems (Inventive Examples 1 and 2) were significantly superior in vulcanization adhesion to brass.

[0043]

[Table 1]

[0044]

[Table 2]

(Explanation of Table A) *1 Manufactured by Showa Denko K.K. Chlorinated polyethylene rubber *2 Maleic anhydride modified chlorinated polyethylene rubber manufactured by Showa Denko K.K. *3 Manufactured by Showa Denko K.K. *4 Sankyo Kasei Trithiocyanuric acid *5 manufactured by Co., Ltd.
Sanshin Chemical Industry Co., Ltd. Tetramethylthiuram disulfide *6 Sanshin Chemical Industry Co., Ltd. Tetramethylthiuram monosulfide *7 Sanshin Chemical Industry Co., Ltd. 2-mercaptobenzothiazole *8 Sanshin Chemical Industry Co., Ltd. ) dibenzothiazyl disulfide *9 manufactured by Sanshin Chemical Industry Co., Ltd. N-cyclohexyl-2-benzothiazyl sulfenamide *10 manufactured by Sanshin Chemical Industry Co., Ltd. N-oxydiethylene-2-benzothiazolyl sulfene manufactured by Sanshin Chemical Industry Co., Ltd. Amide *11
Asahi Carbon Co., Ltd. SRF grade carbon black*
12 Trimellitic acid ester manufactured by Adeka Argus Chemical Co., Ltd. *13 Sulfur in the above formula (II) was replaced with sulfur or a sulfur donor.

(Example 2) MDCA Content The various rubber compositions shown in Table B were used to conduct the performance evaluation test. The results are shown in Table B. From Table B, when MDCA is less than 0.5 parts by weight (Comparative Examples 15 and 16), the elastic modulus of the vulcanized rubber is insufficient, while when it is more than 5 parts by weight (Comparative Example 17), the vulcanized adhesion to brass is insufficient. It is clear that when the MDCA content is 0.5 to 5 parts by weight (Inventive Examples 3 to 7), the properties are insufficient and both elastic modulus and adhesiveness are satisfied.

[0047]

[Table 3]

(Example 3) The performance tests described above were conducted using various rubber compositions shown in Table C containing trithiocyanuric acid. The results are shown in Table C. Table C shows that when trithiocyanuric acid is less than 0.2 parts by weight (Comparative Examples 18 and 19), the elastic modulus of the vulcanized rubber is insufficient;
0), the vulcanization adhesion with brass is insufficient, and both the elastic modulus and adhesiveness are satisfied when the trithiocyanuric acid content is 0.2 to 10 parts by weight (Invention Examples 6, 8 to 11). ).

[0049]

[Table 4]

(Example 4) Sulfur Content The various rubber compositions shown in Table D were used to conduct the performance evaluation test described above. The results are shown in Table D. From Table D, sulfur is less than 0.05 parts by weight (
In Comparative Examples 21 and 22), the vulcanized adhesion to brass was insufficient, while in the case of more than 5 parts by weight (Comparative Example 23), the elastic modulus of the vulcanized rubber tended to be insufficient, and the elastic modulus and adhesive properties Both of these conditions are satisfied when the sulfur content is 0.05 to 5 parts by weight (
It is clear that invention examples 12 to 16).

[0051]

[Table 5]

(Example 5) Relationship between MDCA content and trithiocyanuric acid content The performance evaluation test described above was conducted using various rubber compositions shown in Tables E and F. The results are shown in Tables E and F. Table E shows the M.D.
A rubber composition containing each of CA, trithiocyanuric acid and sulfur in amounts specified in the present invention,
Regarding DCA, there are various rubber compositions that are varied. Table F shows various rubber compositions in which MDCA, trithiocyanuric acid, and sulfur are each contained in the amounts specified in the present invention, and in which trithiocyanuric acid is varied. It is. From Tables E and F, even if each of MDCA, trithiocyanuric acid and sulfur is contained in the amount specified in the present invention, if the formula (I) is not satisfied (Comparative Examples 24 to 26), addition of MDCA, trithiocyanuric acid, and sulfur is The elastic modulus of sulfur rubber is insufficient and both the elastic modulus and adhesiveness are satisfied when the above formula (I) is satisfied (Invention Example 1
7 to 26).

[0053]

[Table 6]

[0054]

[Table 7]

(Example 6) Relationship between MDCA content and sulfur content The performance evaluation test described above was conducted using various rubber compositions shown in Table G. The results are shown in Table G. Table G shows various rubber compositions in which MDCA, trithiocyanuric acid, and sulfur are each contained in amounts specified in the present invention, and in which sulfur is varied. be. Table G shows that even if each of MDCA, trithiocyanuric acid and sulfur is contained in the amount specified in the present invention, the formula (II) is not satisfied (Comparative Example 2
7 to 31) lack vulcanization adhesion to brass, and only cases satisfying the above formula (II) (invention examples 27 to 31) satisfy both elastic modulus and adhesion. That is clear.

[0056]

[Table 8]

[0057]

The present invention provides a chlorinated polyethylene rubber composition that has excellent vulcanization adhesion to metals such as brass and physical properties of vulcanized rubber, particularly modulus, and has a relatively simple compounding system. Therefore, by applying the chlorinated polyethylene rubber-based rubber composition of the present invention to the rubber parts of various products composed of metal/rubber composites such as tires, belts, molds, rolls, and hoses, the rubber parts can be improved. Products with better physical properties, durability, etc. will be provided.

[Brief explanation of the drawing]

FIG. 1 is a front view showing a sample for vulcanization adhesion test between rubber and brass.

[Explanation of symbols]

1 Rubber 2 Brass plate 3 Cellophane paper

Claims (1)

[Claims] Claim 1: Chlorinated polyethylene rubber (A) and/or maleic anhydride modified chlorinated polyethylene rubber (
B) For 100 parts by weight, dicyclohexylamine salt of 2-mercaptobenzothiazole (abbreviation: MDCA) (
C) 0.5 to 5 parts by weight, trithiocyanuric acid (D) 0.
2 to 10 parts by weight and 0.05 to 5 parts by weight of sulfur (E), and contains MDCA (C), trithiocyanuric acid (
D) and sulfur (E) content, the following formula (I
) and (II). (MDCA(phr))×(trithiocyanuric acid(phr))≧0.5...(I)
Sulfur (phr) /MDCA (phr) ≧0.1
...(II)