JPH1135702A - Rubber/cord composite - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rubber/cord composite improved in adhesion between a rubber and org. fibers and in durability by treating org. fibers with a treating liquid contg. an epoxy compd., an epoxy-modified styrene-butadiene copolymer rubber latex, and a thermally reactive water-soluble urethane resin and then with a liquid contg. resorcin. formalin, and a rubber latex and vulcanizing an unvulcanized rubber integrally with the fibers. SOLUTION: Org. fibers are treated with a treating liquid contg. 10-50 pts.wt. epoxy compd., 100 pts.wt. epoxy-modified styrene-butadiene copolymer rubber latex. and 10-100 pts.wt. thermally reactive water-soluble urethane resin, dried at 100-150 deg.C and thermally treated at 200-250 deg.C to give org. fibers with 3-8 wt.% treating liquid deposited thereon. Thus treated fibers are then treated with a treating liquid comprising a resorcin-formalin precondensate and a rubber latex, dried at 100-150 deg.C, and thermally treated at 200-250 deg.C to give org. fibers with 2-6 wt.% treating liquid deposited thereon. An unvulcanized rubber is vulcanized integrally with the org. fibers treated as above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber / cord suitable for use in tires, belts, hoses and the like, which has excellent adhesiveness and durability using organic fibers such as aramid fibers and polyester fibers as cords. Related to the complex.

[0002]

2. Description of the Related Art Organic fibers (for example, polyester fibers and aramid fibers) are attracting attention as rubber reinforcing agents such as tire cord materials because of their various properties and light weight.
However, there has been a problem that polyester fibers and aramid fibers have poor adhesion to rubber. As an adhesive method for solving such a problem, for example, a method in which an organic fiber is treated with an epoxy compound and then treated with resorcinol-formalin rubber latex (RFL), which has been conventionally widely used as an adhesive with rubber, is disclosed in As disclosed in JP-A-824492, there is a method of treating with a mixed solution of an epoxy compound, vinyl pyridine latex and blocked isocyanate, followed by treatment with RFL, but none of these methods still has sufficient adhesive strength. In particular, in the future, when organic fibers as described above in the development of lightweight tires and the like corresponding to the US fuel efficiency regulations CAFE are used, for example, as tire cords, it is expected that the adhesive durability will become increasingly important. Further improvement is needed.

[0003]

SUMMARY OF THE INVENTION Accordingly, the present invention solves the above-mentioned problems in the case where the organic fiber is used as a cord, and retains the characteristics of the organic fiber itself, and combines the rubber with the organic fiber. It is an object of the present invention to provide a rubber / cord composite having improved adhesiveness and further improved durability.

[0004]

According to the present invention, an organic fiber is prepared by (a) an epoxy compound, (b) an epoxy-modified styrene / butadiene copolymer rubber (SBR) latex, and (c) a heat-reactive water-soluble polymer. Treated with a first treatment liquid composed of a urethane resin, and then treated with a second treatment liquid (RFL treatment liquid) composed of resorcin, formalin and rubber latex,
Then, a rubber / cord composite obtained by integrally vulcanizing the unvulcanized rubber is provided.

According to the present invention, good adhesion between an organic fiber such as a polyester fiber and an aramid fiber and rubber can be achieved by a mixture of an epoxy compound, an epoxy-modified SBR latex and a heat-reactive water-soluble urethane resin (first treatment). Liquid), followed by treatment with an RFL mixture (second processing liquid), and vulcanization integrally with the unvulcanized rubber.

[0006] Representative examples of the organic fibers used in the present invention are polyester fibers and aramid fibers. A typical example of the polyester fiber is polyethylene terephthalate fiber, which can be any polyester fiber conventionally used for reinforcing rubber. As a commercially available product, for example, Tetron, which is commercially available from Toray Industries, Inc., is known. I have. On the other hand, the aramid fiber (aromatic polyamide fiber) can be any aramid fiber conventionally used for rubber reinforcement, and as commercial products, for example, Kevlar commercially available from DuPont, Twaron manufactured by AKZO, Technora manufactured by Teijin Limited Etc. are known.

The first processing liquid used in the present invention is (a)
It is composed of an epoxy compound / (b) an epoxy-modified SBR latex / (c) a heat-reactive water-soluble urethane resin, and the preferred composition ratio (based on solid content weight) is as follows. (1) 0.1 ≦ (a) / [(b) + (c)] ≦ 2 and (2) 0 <(c) / (b) ≦ 2 (a) / [(b) + (c) Is less than 0.1, sufficient adhesiveness cannot be obtained, and if it exceeds 2, the tensile strength of the cord tends to decrease. If the (c) / (b) ratio exceeds 2, the cord becomes hard, and the fatigue property tends to decrease, which is not preferable.

The epoxy compound used as the component (a) in the first treatment liquid of the present invention has a glycidyl group in the molecule.
Examples thereof include known epoxy compounds having one or more polyols, preferably polyol epoxy compounds such as glycerol polyglycidyl ether, diglycerol polyglycidyl ether, and sorbitol polyglycidyl ether. If the amount of the epoxy compound in the first treatment liquid is too small, the initial adhesive strength may decrease. On the contrary, if the amount is too large, the water-resistant adhesiveness may decrease and the fiber tensile strength may decrease.

The epoxy-modified SBR latex used as the component (b) in the first treatment liquid of the present invention is an SBR latex containing a monomer containing an epoxy group, and the ratio of the monomer containing an epoxy group to the total monomer is 1%. Mol% or more, more preferably 2 to 4 mol%. Examples of such an epoxy-containing monomer include, for example, glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether and the like. These can be emulsion-copolymerized according to a conventional method to obtain a desired epoxy-modified SBR latex. . The epoxy-modified SBR latex has a styrene / butadiene monomer ratio (weight ratio) of 5/95 to 45.
It is preferable to use a copolymer rubber latex in the range of / 55. If the styrene content in the styrene / butadiene weight ratio is too small, processability such as gum up to a roll during dipping may be reduced, and if too large, the adhesive strength may be reduced. The SBR latex can be produced by any conventionally known emulsion polymerization method, and preferably has a solid content of 30 to 60% by weight. On the other hand, if the amount of the SBR latex blended in the first treatment liquid is too small, there is a possibility that the initial adhesion and the adhesion during heating may be reduced, while if it is too large, the dipping processability may be reduced.

The heat-reactive water-soluble urethane resin used as the component (c) in the first treatment liquid of the present invention includes:
For example, it is preferable to use a compound having three or more thermally dissociable blocked isocyanate groups in one molecule as shown by the formula (I).

[0011]

Embedded image

(Wherein, A represents an organic polyisocyanate residue having a functionality of 3 to 5, Y represents a residue of a blocking agent that releases an isocyanate group upon heating, and Z represents at least one active group in the molecule. X represents a residue of a compound having a hydrogen atom and at least one anion-forming group;
Represents the residue of a compound having a hydroxyl group (e.g., a polyhydric alcohol, a polyhydric amine, an amino alcohol, a polyester polyol, or the like) having a number of active hydrogen atoms and an average molecular weight of 5,000 or less, and p + q is an integer of 2 to 4. (However, q ≧
0.25), and r is an integer of 2 to 4. )

Examples of the urethane resin of the formula (I) include, for example, a polyether polyol compound of the formula (I) wherein the substituent X has 2 to 4 hydroxyl groups (for example, bisphenol A
Of the ethylene oxide polyadduct of the formula (I), or
A polyurethane resin in which the substituent X is a residue of a polyester polyol compound having 2 to 4 hydroxyl groups (for example, a lactone polyester polyol compound obtained by ring-opening polymerization of caprolactone). If the amount of the heat-reactive water-soluble urethane resin compounded in the first treatment liquid of the present invention is too small, the adhesive strength may be reduced. Conversely, if the amount is too large, the cord becomes hard and the fatigue resistance is reduced. There is a risk.

The first treatment liquid according to the present invention can be prepared by mixing the above components by a general method, and if necessary, a surfactant such as sodium sulfosuccinate for improving dispersibility is added. be able to. The method for treating the organic fibers with the first treatment liquid may be the same as the method for treating general fibers, such as by applying a dipping roll into the liquid or spraying. The amount of the first treatment liquid adhering to the organic fibers is preferably 3 to 8% by weight. After the treated organic fiber is dried at a temperature of, for example, 100 to 150 ° C., it is further heat-treated at a temperature of, for example, 200 to 250 ° C.

An epoxy compound is used in an amount of 10 to 50 per 100 parts by weight of the epoxy-modified SBR latex as the first treatment liquid.
It is preferable to mix 10 to 100 parts by weight of the heat-reactive polyurethane resin.

The organic fibers treated with the first treatment liquid according to the present invention are then subjected to RFL treatment, which is conventionally used as an adhesive between organic fibers such as polyamide fibers and polyester fibers and rubber. The second processing solution may be one commonly used in the art, and typically has a resorcinol-formalin precondensate / rubber latex (for example, 30 to 40 g such as styrene-butadiene latex or vinylpyridine-styrene-butadiene terpolymer latex). (60% emulsion) = 1: 2 to 1:20 (weight ratio), and in addition to these components, an aqueous dispersion of blocked isocyanate can be blended if necessary.

The processing method of the second processing liquid according to the present invention can be the same as the conventional method. The amount attached to the organic fibers is preferably 2 to 6% by weight. The treated organic fiber is dried (for example, at a temperature of 100 to 150 ° C.) and further heat-treated at a temperature of, for example, 200 to 250 ° C.

The aramid fibers treated with the first treatment liquid and the second treatment liquid according to the present invention can be made of unvulcanized rubber (for example, natural rubber, SBR rubber, polyisoprene rubber, polybutadiene rubber) and vulcanization compounding agent (for example, Sulfurizing agents, vulcanization accelerators,
(Carbon black, antioxidant, filler, etc.) and vulcanized integrally according to a conventional method to form a rubber / cord composite.

According to the present invention, the organic fibers are first treated with a first treatment liquid comprising a specific epoxy compound, an epoxy-modified styrene-butadiene rubber latex and a heat-reactive water-soluble urethane resin, and then subjected to RFL treatment. By the integrated vulcanization with the unvulcanized rubber, the adhesiveness between the rubber and the cord of the organic fiber is excellent, and the durability of the rubber product containing the organic fiber is remarkably enhanced.

[0020]

EXAMPLES The present invention will be further described below with reference to Examples and Comparative Examples, but it goes without saying that the scope of the present invention is not limited to these Examples.

Examples 1 to 5 and Comparative Examples 1 to 6 Rubber compositions to be adhered (A (PCR carcass), B (belt)) having the following contents (parts by weight) as unvulcanized rubber compounds:
Using polyester fiber as a fiber material (Toray Industries, Inc.)
A commercially available Tetron (1500 denier / 2) was used.

[0022] Ingredient A (parts by weight) B (parts by weight) Natural rubber 100 100 Zinc white 5 10 Stearic acid 1 0 Carbon black 60 60 Antioxidant 1 1 Aromatic oil 10 0 Sulfur 2.5 5 Vulcanization accelerator (Sulfenamide) 1 0.5 Cobalt naphthenate 01

First, a polyester fiber (1500 denier / 2) was immersed in a first treatment solution containing the following compound in the composition shown in Table I, and subjected to a drying heat treatment (drying at 100 ° C. × 1).
Min, heat treatment 240 ° C. × 1 minute). (A) Epoxy resin: glycerol diglycidyl ether (b) SBR latex: (i) Unmodified SBR latex: styrene (St) / butadiene (Bd) (weight ratio) = 30/70. (Ii) Epoxy-modified SBR latex (E / St / Bd
= 2/28/70 (weight ratio) (epoxy: glycidyl methacrylate) (c) Thermal reaction type water-soluble urethane resin: Elastron BN04 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.

Next, the polyester fiber is added with a solid concentration of 20%.
And heat treatment (drying 100 ° C. × 1 minute, heat treatment 240) with an RFL treatment solution (composition: resorcin / formaldehyde (molar ratio) = 1 / 1.7, resorcin / formaldehyde / VP latex (weight ratio) = 16/100) ℃ x 1
Minute). The vulcanization conditions were 150 ° C. × 30 minutes. The results are shown in Table I.

[0025]

[Table 1]

As is clear from the results in Table I, when no latex is added, the adhesive strength is low, and when the amount of latex is large, the adhesiveness tends to decrease, and a problem occurs in operability. On the other hand, even if the urethane resin is not added, the adhesion is low. On the other hand, if the amount is too large, the yarn becomes hard and the adhesive strength is reduced. Others
It has been confirmed that when an aqueous dispersion of blocked isocyanate is used, particularly the water-resistant adhesiveness is reduced due to the influence of a dispersant (surfactant).

Example 6 In the first treatment liquid comprising the above-mentioned epoxy resin, SBR latex (unmodified and epoxy-modified) and urethane resin = 2/5/5 (solid content weight ratio), the epoxy group-containing monomer in the SBR latex was used. The molar ratio (%) of 0%, 2
% And 4%, the overcure peeling force and the water-resistant peeling of the composite obtained were measured. The compounded rubber was A, and the organic fibers were polyester (1500 denier / 2). As the second processing liquid, a 20% RFL liquid was used as in each of the above examples, and the processing conditions were the same as in each of the above examples. The result is, as shown in FIG. 1, clearly showing the epoxy modification effect.

Overcure peeling force (kgf / 25 mm):
Measured in accordance with JIS-K-6301 Water resistant peeling (kgf / 25mm): Measured in accordance with JIS-K-6301

Example 7 In the same manner as in Example 6, the mixture of B was used as the rubber to be applied, and aramid (1,500 denier / 2) was used as the organic fiber.
Was used to test the effect of the amount of epoxy modification of the epoxy-modified SBR latex on water-resistant peeling. The results are as shown in the figure, and the epoxy modification effect is apparent.

Example 8 In the same manner as in Example 6, the compound A was used as the rubber to be adhered, and polyester (1500 denier /
Using 2), the effect of the amount of urethane added on water-resistant peeling was tested. The results are as shown in FIG. 3, and the effect of adding urethane is clear. The epoxy resin addition amount was fixed at 2 parts by weight, and the SBR addition amount was fixed at 5 parts by weight.

[0031]

As described above, according to the present invention, an organic fiber (aramid; polyester) is treated with a first treating solution comprising an epoxy compound, an epoxy-modified styrene / butadiene rubber latex, and a heat-reactive water-soluble urethane resin. After treatment with a second treating solution comprising resorcinol, formalin and rubber latex, the unified vulcanized rubber is integrally vulcanized to obtain a better adhesion between the rubber and the fiber as compared with the conventional one, and furthermore, the organic fiber The durability of the product used is significantly improved.

[Brief description of the drawings]

FIG. 1 is a graph showing the effect of the epoxy content of an epoxy-modified SBR latex on the water-peeling resistance of the rubber / cord composite obtained in Example 6.

FIG. 2 is a graph showing the effect of the epoxy content on the water-peeling resistance of the rubber / cord composite obtained in Example 7.

FIG. 3 is a graph showing the effect of the amount of urethane resin added on the peel resistance of the rubber / cord composite obtained in Example 8.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazumasa Nakakita 2-1 Oiwake, Hiratsuka-shi, Kanagawa Yokohama Rubber Co., Ltd. Hiratsuka Works (72) Inventor Takayuki Fukutomi 2-1 Oiwake, Hiratsuka-shi, Kanagawa Yokohama Rubber Hiratsuka Factory

Claims (4)

[Claims] 1. An organic fiber comprising: (a) an epoxy compound;
(B) treatment with a first treatment liquid comprising an epoxy-modified styrene / butadiene copolymer rubber (SBR) latex and (c) a heat-reactive water-soluble urethane resin, and then resorcinol;
A rubber / cord composite which is treated with a second treatment liquid comprising formalin and rubber latex, and is integrally vulcanized with unvulcanized rubber. 2. The rubber / cord composite according to claim 1, wherein the ratio of the monomer containing an epoxy group to the total monomer in the epoxy-modified SBR latex is 1 mol% or more. 3. The rubber / code composite according to claim 1, wherein the heat-reactive water-soluble urethane resin has three or more heat-dissociable blocked isocyanate groups in one molecule. 4. The blending ratio of the components (a), (b) and (c) is (1) 0.1 ≦ (a) /
[(B) + (c)] ≦ 2, and (2) 0 <(c) /
The rubber / cord composite according to claim 1, wherein (b) ≦ 2.