JPH0463902B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of adhering a galvanized steel cord and a rubber composition, and more specifically, the present invention relates to a method of adhering a galvanized steel cord and a rubber composition, and more specifically, by closely adhering a galvanized steel cord whose surface is coated with a higher fatty acid ester and a rubber composition of a specific composition, and heat-treating the cord. This invention relates to a method for adhering the two well. In recent years, products with particularly excellent strength and performance have been required for steel tires, belts, reinforced hoses, etc., and in response to this demand, composites made by bonding metal steel cord and rubber composition have been developed. Widely used. However, in order to achieve a high reinforcing effect by combining a steel cord and a rubber composition, strong adhesion between the two is required. Conventionally, as a method of adhering this steel cord and a rubber composition, for example, the surface of the steel cord is coated with zinc, brass, etc., and on the other hand, the rubber composition is coated with a resin such as resorcinol-formaldehyde resin, or a metal salt such as an organic cobalt salt. There is a method of adhering the two by adding such as. However, this method has drawbacks such as insufficient adhesion between the rubber composition and metal during vulcanization, and problems such as blooming of unvulcanized rubber occurring during processing steps. A further improved method is a method in which a rubber composition in which a liquid polyisoprene rubber having a carboxyl group at the end is added to a steel cord whose surface is coated with brass etc. in the same manner as the above method is bonded to a diene rubber ( JP-A-54-51146, JP-A-54
-36385, JP-A-55-48231) are known. However, even with this method, the pulling force and amount of rubber adhesion decrease after moist heat treatment for normal galvanized steel cords, and good adhesion is achieved only for galvanized steel cords with extremely clean surfaces. In order to be effective, the working environment needs to be cleaned to be dust-proof and moisture-proof, which has the drawback of increasing the cost required for the bonding work. As a result of research conducted by the present inventor to solve these drawbacks of the conventional technology, it was found that by coating the surface of a galvanized steel cord with a higher fatty acid ester, the adhesion with a rubber composition of a specific composition is significantly improved. In particular, it has good water resistance and moist heat resistant adhesion, and it is also possible to obtain good adhesion without applying special dust-proof and moisture-proof treatment to the galvanized steel cord, and to reduce thermal energy consumption in the vulcanization process. The present invention was completed after discovering that it can be done. That is, in the present invention, on the surface of the galvanized steel cord, 0.1 to 2.0 per kg of the galvanized steel cord is applied.
After applying g higher fatty acid ester, 100 parts by weight of diene rubber, 3 to 7 parts by weight of liquid polyisoprene rubber having 1 to 10 carboxyl groups or hydroxyl groups per molecule, 1 to 6 parts by weight of organic cobalt salt, 3 parts by weight or more of a halogen-containing organic compound and 2 to 2 parts by weight of sulfur
This is a method of adhering a galvanized steel cord and a rubber composition, which is characterized by adhering a rubber composition containing 4 parts by weight and integrating the rubber composition by heat treatment. The present invention will be explained in detail below. The diene rubber used in the present invention may be of any type as long as it is used in ordinary composites of steel cord and rubber compositions, but specific examples include natural rubber (NR), polyisoprene rubber (IR), and polystyrene rubber. One or a mixture of two or more selected from butadiene copolymer rubber (SBR) and butadiene rubber (BR) is suitable. In particular, these diene rubbers have good compatibility with polyisoprene rubber, which is a liquid rubber, and when the two are mixed, a uniform mixture is obtained. The liquid polyisoprene rubber used in the present invention has a viscosity average molecular weight of 20,000 to 40,000, and 1 to 10 carboxyl or hydroxyl groups per molecule, preferably 2.5
It is preferable to have 5 to 5 pieces, and specific examples include LIR403 and LIR410 manufactured by Kuraray Co., Ltd. The appropriate amount of the liquid polyisoprene rubber is 3 to 7 parts by weight per 100 parts by weight of the diene rubber; if it is less than 3 parts by weight, good adhesion cannot be obtained, and if it exceeds 7 parts by weight, the tensile strength is poor. This is not preferable because physical properties such as modulus and tensile strength decrease. Examples of the organic cobalt salt used in the present invention include cobalt naphthenate, cobalt octylate, cobalt stearate, cobalt palmitate, cobalt rosin acid, and cobalt propionate, among which cobalt naphthenate is preferred. The amount of the organic cobalt salt is the same as that of diene rubber.
1 to 6 parts by weight is appropriate for 100 parts by weight,
If it is less than 1 part by weight, the adhesion level will not achieve the objective, and 6
If the amount exceeds 1 part by weight, the aging physical properties of the rubber will be significantly lowered, which is not preferable. The halogen-containing organic compound used in the present invention is preferably a chlorine- or bromine-containing organic compound, and the amount thereof is 3 parts by weight or more, preferably 3 to 7 parts by weight, based on 100 parts by weight of the diene rubber. It is. If it is less than 3 parts by weight, the rubber-metal adhesion reaction cannot be activated, while if it exceeds 7 parts by weight, it may have an adverse effect on the rubber crosslinking reaction and retard the crosslinking. Further, 2 to 4 parts by weight of sulfur is used as a crosslinking agent per 100 parts by weight of the diene rubber. If it is less than 2 parts by weight, the adhesive reaction will not proceed, and if it exceeds 4 parts by weight, problems such as blooming of unvulcanized rubber and lack of scorch stability will occur. The rubber composition according to the present invention contains the above-mentioned components, and other components include rubber vulcanizing agents such as vulcanization accelerators and vulcanization activators, carbon black, silica, clay,
Fillers such as calcium carbonate, magnesium carbonate, and zinc white, softeners such as bindal and oil, antiaging agents, and coloring agents can be used as appropriate. Although a galvanized steel cord is used as the metal material according to the present invention, its shape is not limited to a cord shape, but a plate shape can also be used without any problem. In the present invention, an ester surface treatment agent is used as the higher fatty acid ester applied to the surface of the galvanized steel cord, and specifically, sorbitan monooleate, pentaerythritol monooleate, or C ₃ - C ₂₈ acetylene thiol Esters of alcohol and fatty acids, polyoxyethylene derivatives of sorbitan monooleate, oleic acid and butanediol 1,4, oleic acid and butanetriol-
Ester-based surface treatment agents mainly composed of 1, 2, and 4 esters, sulfurized partial ester compounds of aromatic polycarboxylic acids, and other sucrose esters, erucic acid dipolyester, palmitic acid triester, etc. as necessary. Various surface treatment agents are included, and commercially available products include those manufactured by Yako Tsunayu Co., Ltd.
KDIIOE, MO3-C manufactured by Kao Soap Co., Ltd.
Examples include K1402B and Metalex SS manufactured by NOF Corporation. The coating amount of the higher fatty acid ester is 0.1 to 2.0 g per 1 kg of galvanized steel cord, and if it is within this range, it can be kept in a normal factory atmosphere without special dust-proof and moisture-proof treatment after coating. However, if it is less than 0.1 g, special dust-proof treatment is required to store the galvanized steel cord, and if it exceeds 2.0 g, the adhesion of the rubber composition decreases, especially when the pulling force is reduced. decreases. One example of the method of adhering a galvanized steel cord and a rubber composition according to the present invention is to first uniformly apply a liquid higher fatty acid ester to the surface of a galvanized steel cord, dry it, and then apply it. On the other hand, a blend of a specific composition containing the diene rubber, liquid polyisoprene rubber, organic cobalt salt, halogen-containing organic compound, and sulfur is uniformly kneaded using a roll mill, Banbury mixer, kneader, internal mixer, etc. A rubber composition is produced. The galvanized steel cord is brought into close contact with the rubber composition and molded into a certain shape.
Bonding can be easily achieved by heat treatment and integration by pressure vulcanization at ℃ for 15 to 40 minutes. As described above, in the present invention, a specific amount of higher fatty acid ester is applied to the surface of a galvanized steel cord, and a rubber composition containing liquid polyisoprene rubber having a carboxyl group or hydroxyl group is adhered to the surface of the galvanized steel cord, and the vulcanized unitary cord is vulcanized. Because the ester group and the carboxyl group or hydroxyl group interact with each other to form a bond, a strong adhesive force can be obtained by exerting a mutual effect. Next, the effects of the present invention will be listed. 1. By the adhesion method of the present invention, it is possible to obtain significantly improved adhesive strength between the galvanized steel cord and the rubber composition in terms of water resistance and moisture and heat resistance. 2. Since the surface of the galvanized steel cord is coated with higher fatty acid ester, the adhesion level can be maintained without special dust-proofing and moisture-proofing treatment in the storage area. 3. Consumption of thermal energy can be reduced in the vulcanization process in heat treatment. Next, the present invention will be explained in more detail with reference to Examples. Reference example Various liquid rubbers are added to the basic rubber composition shown in Table 1 below, and the result is the standard SRIS 3602 of the Japan Rubber Association.
-1972 “Test method for synthetic rubber BR” 6, 2, 2,
The rubber compositions shown in Table 2 were obtained by mixing according to Method B. Next, each of the above rubber compositions was adhered to a thickness of 15 mm on a 4.1 mm diameter galvanized steel cord that had been stored in a desiccator and treated to be dust-proof and moisture-proof.
The rubber composition/galvanized steel cord composite (hereinafter referred to as
A rubber/cord composite) was obtained. The factory atmosphere during this work has a relative humidity of 60 to 70%.
The temperature was 25-30°C, and the amount of dust was 0.2g/ ^1m3 . Each of the rubber/cord composites described above was subjected to an adhesion test and a heat-and-moisture resistance test, and the pull-out force and rubber elastic modulus were measured. The results are shown in Table 3.

【table】

【table】

【table】

[Table] As mentioned above, in the addition tests of various liquid rubbers, the functional groups were hydroxyl group (-0H), carboxyl group (-
Liquid polyisoprene with COOH) has been found to improve adhesion levels. Example 1 1 kg of galvanized steel cord with various surface treatment agents applied to the surface of 4.1mmφ galvanized steel cord
After applying 1.0 to 1.2g per rubber composition, the rubber compositions 1-H, 1-I, 1-J, and 1-K of the reference examples were adhered and heat-treated under the same conditions as the reference examples. /An adhesion test was conducted on the cord composite. The results are shown in Table 4. The adhesion test was expressed in terms of pull-out force reduction rate and rubber coverage reduction rate.

【table】

[Table] From the results of Example 1, the combination of a rubber composition in which a higher fatty acid ester is applied as a surface treatment agent to a galvanized steel cord and a carboxyl group-introducing liquid IR is added exhibits the best adhesion. In particular, after surface treatment of the galvanized steel cord, it is observed that the adhesion level is maintained even when stored in a factory atmosphere. Example 2 Adhesion level depending on the amount of carboxyl group-introduced polyisoprene added. A rubber composition containing LIR403 manufactured by Kuraray Co., Ltd. as a liquid polyisoprene rubber with 2.9 carboxyl groups introduced into the basic rubber composition shown in Table 1 of the reference example, and a rubber composition manufactured by Yako Tsunayu Co., Ltd. as a higher fatty acid ester.
A rubber/cord composite obtained by pressure vulcanization of a 4.1mmφ galvanized steel cord coated with KR541T under the same conditions as the reference example was subjected to a pullout test after being left for 14 days under humid heat conditions of 50°C and 98RH. A graph of the results is shown in FIG. From FIG. 1, it is recognized that the amount of liquid polyisoprene rubber added is preferably 3.0 to 7.0 parts by weight per 100 parts by weight of diene rubber. Example 3 Effect of coating amount of higher fatty acid ester surface treatment agent on adhesion level. Using rubber compositions 1-I and I-K of reference examples,
Varying amounts of higher fatty acid ester surface treatment agent were applied to the surface of a 4.1mmφ galvanized steel cord, and the results were obtained by applying pressure vulcanization after leaving the coating in a factory atmosphere for 3 days under the same conditions as the reference example. Figure 2 shows the results of a heat-and-moisture adhesion test conducted on the rubber/cord composite after it was left for 14 days under humid conditions of 50°C and 98RH. As higher fatty acid ester surface treatment agents, KD110E manufactured by Yako Tsunayu Co., Ltd., MO3-C manufactured by Kao Soap Co., Ltd.
The average value of the results of tests conducted using K1402B and Metalex SS manufactured by NOF Corporation is shown in the graph of FIG. From the results shown in FIG. 2, it is recognized that the best coating amount of the higher fatty acid ester surface treatment agent is 0.1 to 2 g/kg of galvanized steel cord. Example 4 Effect of adhesion level depending on the type of organic acid cobalt. High fatty acid ester (Yako Tsunayu Co., Ltd.) is applied as a surface treatment agent to the surface of a 4.1mmφ galvanized steel cord.
KD110E) was coated with 1.5g/kg of galvanized steel cord and left in the same factory atmosphere as in the reference example for 3 days. FIG. 3 shows the results of an adhesion test and a moist heat resistance test on the rubber/cord composite obtained by pressure vulcanization and integration under the following conditions.

【table】

[Table] Example 5 Rubber composition shown in Table 6 containing liquid polyisoprene with various numbers of carboxyl groups (per molecule) and KD110E manufactured by Yako Tsunayu Co., Ltd. as an ester surface treatment agent. A galvanized steel cord coated with 1.2 g/kg of galvanized steel cord was left in the same factory atmosphere as in the reference example for 3 days, and then vulcanized under the conditions of 160℃ x 20 minutes and 150℃ x 20 minutes. It was integrated with. The results of the adhesion test of the obtained rubber/cord composite are shown in FIG.

[Table] From the above results, it is possible to bond with low energy in the vulcanization process during heat treatment, and the number of carboxyl groups introduced into the liquid rubber is 2.5 to 5 groups/
It is recognized that one molecule is best.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the effect of the amount of liquid polyisoprene rubber added on adhesion in the bonding method of the present invention, FIG. 2 is a graph showing the effect of the amount of higher fatty acid ester surface treatment agent on adhesion, and FIG.
FIG. 4 is a graph showing the influence of the type of organic acid cobalt on adhesion, and FIG. 4 is a graph showing the influence of liquid polyisoprene rubber and vulcanization conditions on adhesion.

Claims (1)

[Claims] 1 After applying 0.1 to 2.0 g of higher fatty acid ester per 1 kg of galvanized steel cord to the surface of the galvanized steel cord, apply 100 parts by weight of diene rubber and 1 to 1 carboxyl or hydroxyl group per molecule.
A rubber composition containing 3 to 7 parts by weight of liquid polyisoprene rubber, 1 to 6 parts by weight of an organic cobalt salt, 3 parts by weight or more of a halogen-containing organic compound, and 2 to 4 parts by weight of sulfur is adhered and integrated by heat treatment. A method of adhering a galvanized steel cord and a rubber composition, characterized by the following: