JPH0482970A - Method for treating rubber-reinforcing fiber with adhesive and toothed belt employing the fiber - Google Patents

Abstract

PURPOSE:To obtain a reinforcing fiber having improved adhesiveness to rubbers and having excellent heat resistance and abrasion resistance by dipping the fiber in a solution containing a RFL liquid having a specific R/F/L wt. ratio and containing a specified amount of a chlorophenol, diping the treated fiber in a rubber paste and subsequently subjecting the dipped fiber to a thermal treatment. CONSTITUTION:When a fiber such as a synthetic fiber is coated with a RFL liquid and subsequently with a rubber paste, the fiber is dipped in a treating solution containing a RFL liquid and a chlorophenol [e.g. 5-bits(2,4- dihydroxybenzyl)-p-chlorophenol] in a wt. ratio of 1/0.03 to 1/0.1, dipped in a rubber paste (preferably chlorosulfonated polyethylene rubber) and subsequently heated 200-240 deg.C to obtain a rubber-reinforcing fiber having improved adhesiveness to rubbers and excellent heat resistance. The RFL liquid has a resorcinol/ formalin mol ratio of 2/1 to 1/2 and a resorcinol.formaline/latex wt. ratio of 1/10 to 1/40. A toothed belt, etc., employing the fiber exhibits a sufficient reinforcing effect as a transmission belt having excellent durability even when used under severe conditions at high temperatures.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for processing rubber reinforcing fibers and a toothed belt using the same fiber, and specifically relates to a toothed belt, a belt, a multi-rib belt, etc. The present invention relates to a method for processing rubber reinforcing fibers such as woven fabrics, core wires, and short fibers used in power transmission belts, and a toothed belt using the same fibers.

[Prior art] In recent years, in response to social demands for automobile exhaust gas regulations, energy conservation, and compactness, the temperature around the engine has been gradually rising compared to the past, and the use of toothed belts has been increasing. Environmental temperatures are rising, and heat resistance and oil resistance are required.In addition, tires are also required to have heat resistance sufficient for use in larger vehicle bodies and high-speed driving. The influence of heat has become extremely large.

For example, in the past, chloroprene rubber has been mainly used for toothed belts, but in high-temperature atmospheres, the rubber hardens, causing early cracks at the belt back surface and tooth base.

Therefore, improvements in the heat resistance of chloroprene rubber have been studied to prevent such early failure of toothed belts, and some improvements have been made, but as long as chloroprene rubber is used, there is a limit, and at present However, sufficient effects have not been achieved.

On the other hand, regarding the improvement of the toothed belt mentioned above, the use of polymers with excellent heat resistance has been considered, and chlorosulfonated polyethylene is suitable for use because it has dynamic fatigue properties, oil resistance, and adhesion properties compared to chloroprene rubber. Attempted.

However, the water resistance of this chlorosulfonated polyethylene is greatly affected by the vulcanization system, especially the acid acceptor, so a comb composition in which an acid acceptor such as MgO or PbO is added to the chlorosulfonated polyethylene is used in the toothed belt body. It has been proposed to use synchronous belts to improve the heat resistance of toothed belts. (See U.S. Patent No. 3,989,868)
However, it has also been proposed to use a hydrogenated nitrile rubber compound, which has excellent heat resistance and oil resistance, for the toothed belt body, and at the same time, it has been proposed to use a hydrogenated nitrile rubber compound with silica, resorcinol, or its modification as a canvas to be used. The use of woven fabrics treated with rubber compositions mixed with methylene donors and methylene donors has also been disclosed. (Jitsukai 63-649
(Refer to Publication No. 48) By the way, in products such as toothed belts,
While progress is being made in improving belt bodies, improving the adhesion of rubber reinforcing fibers to rubber in high-temperature environments has recently been studied as an important issue.

Conventionally, the bonding treatment of rubber reinforcing fibers with rubber has generally been carried out using resorcinol-formalin-latex (hereinafter abbreviated as RFL) or reactive compounds such as epoxy compounds, isocyanates, and ethylene thiourea. . Specifically, there is a one-stage treatment method in which the adhesive is treated with an adhesive liquid containing these reactive compounds and RFL, and a two-stage treatment method in which the adhesive is treated with an adhesive liquid containing the reactive compound and then further treated with RFL.

Among these, in bonding heat-resistant hydrogenated nitrile rubber compounds to fibers, after one-stage treatment using RFL liquid and pretreatment with isocyanate solution, epoxy solution, etc.
A two-stage treatment method using RFL liquid is applied, and the RFL liquid is acrylonitrile containing 3% or more of carboxyl groups.
Butadiene latex is used at a given solids ratio with RFL. (Refer to Special Publication No. 60-24131) [
[Problems to be Solved by the Invention] However, although the hydrogenated nitrile rubber compound as described above has excellent heat resistance and has improved adhesive strength with fibers, the adhesion treatment using the conventional method described above does not result in formation on the fiber surface. The adhesive coating (RFL coating) easily oxidizes and generates reactive radicals at high temperatures of 100 to 140°C.
Organic fibers that do not have sufficient thermal stability are more severely degraded by these radicals, resulting in lower adhesion to rubber and lower strength.

In particular, in toothed belts such as those described above, stress is concentrated at the root of the belt teeth, so when the belt runs under high temperatures, the cover canvas in this area will undergo thermal deterioration, making it more likely to break and causing premature damage. There was a problem in that the belt was damaged due to cracks at the root of the teeth.

The present invention addresses these circumstances and aims to solve these problems. In particular, the weight ratio of resorcin formalin to latex is specified, and a specific amount of chlorophenol is added to the RFL liquid to improve fiber production. The purpose is to increase the adhesion between the fiber and rubber and improve the abrasion resistance of the fiber.

Further, the present invention reduces the thermal deterioration of the cover canvas after the toothed belt is run for a long time in a high temperature environment by strongly holding the reinforcing fibers, thereby improving the durability of the belt. is also the purpose.

[How to solve the problem] That is, in the present invention, after adhering fibers to a first treatment liquid of RFL liquid consisting of a resorcinol-formalin solution and rubber latex, adhesive treatment of rubber reinforcing fibers coated with rubber glue is performed. A method in which the fibers are prepared in such a way that the molar ratio of resorcinol to formalin is 2/1 to 1/2, and the weight ratio of the resin content of the initial condensate of resorcinol-formalin to the rubber content of latex is 1/10 to 1/40. and immersed in an RFL liquid containing a solution containing chlorophenol and having a weight ratio of RFL liquid and chlorophenol of 110.03 to 110.1, then immersed in rubber glue, and heated at 200 to 240°C. This is a method of baking.

The fibers used here include nylon 6, nylon 66, polyester, aromatic polyamide, vinylon, rayon, etc., various organic fibers, glass fibers, carbon fibers, etc., and their forms include monofilament, multifilament yarn, and twisted cord. Besides, it includes all textiles as structures.

These fibers are used as cover canvas for toothed belts, ■belts, multi-ribbed belts, etc., or as core wires for reinforcing cords, depending on their usage.

The invention as set forth in claim 2 resides in a toothed belt in which the bonded rubber reinforcing fiber is used as a cover fabric for the belt teeth.

The types of combs to which the treated fibers are attached include natural rubber (NR), implen comb (IR), styrene butadiene rubber (SBR), butadiene rubber (BR), chloroprene rubber (CR), and nitrile rubber. (NBR), chlorosulfonated polyethylene rubber (C5M), alkylated chlorosulfonated polyethylene rubber (AC8M), hydrogenated acrylonitrile-butadiene rubber (hydrogenated nitrile Among them, rollosulfonated polyethylene rubber, alkylated chlorosulfonated polyethylene rubber, and hydrogenated nitrile rubber have good heat resistance.

Further, the chlorophenol contained in the RFL liquid used in the present invention is, for example, 2,5-bis(2,4-dihydroxybenzyl)-P-chlorophenol, 2,6-bis(2,4
-dihydroxyphenylmethyl)-4-chlorophenol, ortho-, meta- or para-chlorophenol, and is usually used by mixing with an aqueous ammonia solution. This chlorophenol is said to have the function of expanding the surface of the fibers to allow sufficient adhesion of the RFL liquid, and serves as an adhesion promoter. The weight ratio of the RFL liquid to chlorophenol (solid content) is 110.03 to 110°1, and 11
If it is less than 0.03, the effect of improving heat resistance is poor;
If it exceeds 0.1, the adhesive force between the fiber and rubber will not improve.

The RFL liquid used here is a mixture of an initial condensate of resorcin and formalin with latex, and the molar ratio of resorcin and formalin is 1/2 to 2/1. R/
If the molar ratio of F becomes less than 1/2 and the molar ratio of formalin increases, only the surface will harden after adhesive application and the internal hardening will be delayed, making it impossible to perform uniform post-treatment. It's for a reason. On the other hand, the molar ratio of R/F is 2/1
This is because if it exceeds this, the adhesiveness becomes strong and curing time is required. In any case, within this range, post-processing can be performed uniformly.

In addition, the weight ratio (RF/L) of the resin content of the initial condensate of resorcinol-formalin to the rubber content of latex is 1/10 to
If it is less than 1/10, the adhesive force between the fiber and rubber will be maintained at a high level, but the abrasion resistance of the fiber will deteriorate rapidly.

Moreover, if it exceeds 1/40, the adhesive force between the fiber and rubber and the abrasion resistance of the fiber will not change.

The latex is a styrene-butadiene-vinylpyridine terpolymer, chlorosulfonated polyethylene, hydrogenated nitrile rubber, epichlorohydrin, natural rubber, SB.
R, latex such as chloroprene rubber and olefin-vinyl ester copolymer.

When RFL-treated fibers are cured and dried, they are first subjected to 6
Pre-dried at 0-120℃ followed by 160-240℃
Baked to completely dry the RFL adhesive. Subsequently, the fibers are subjected to an overcoat treatment for adhering rubber paste, followed by preliminary drying at 60 to 120°C, followed by baking at 200 to 240°C. The rubber glue used for overcoat treatment is a rubber composition that has excellent adhesion to rubber, such as chlorosulfonated polyethylene, alkylated chlorosulfonated polyethylene, or hydrogenated nitrile rubber composition, isocyanate, and a solvent such as methyl ethyl ketone or toluene. Consisting of

[Action] Impregnated with RFL liquid containing chlorophenol as described above,
Rubber reinforcing fibers coated with adhesive rubber retain their heat resistance and have a high strength retention rate even after heat aging when used in high-temperature environments, such as toothed belts, ■belts, multi-ribbed belts, etc. Provides sufficient reinforcement for power transmission belts used under high temperatures.

[Example] The present invention will be described in detail below with further reference to the accompanying drawings.

FIGS. 1 and 2 show a canvas as the rubber-reinforcing treated fiber, and show an example of a toothed belt in which the canvas is treated in the same way as described above and used as a cover canvas.

FIG. 1 is a cross-sectional perspective view of a toothed belt according to the present invention, in which a toothed belt 1 has a core made of a plurality of toothed rubbers 2 and cords of glass fiber, aramid fiber, carbon fiber, etc. along the belt longitudinal direction. It consists of a back rubber 4 in which wires 8 are embedded, and a cover canvas 5 is stuck to the surface of the tooth rubber 2.

As the cross-sectional view of the cover canvas 5 is shown in FIG. 2, first, a first adhesive layer made of RFL liquid containing a phenolic condensation product is coated on the surfaces of the warp yarns 5b and the weft yarns 5a constituting the fabric. 6 is coated, and a second adhesive layer 7 made of rubber glue is adhered to the surface thereof.

In addition, the cover canvas used here is suitably made of nylon 6, nylon 66, and polyester, but is not limited to these, and may be made of organic fibers such as aromatic polyamide, vinylon, rayon, and cotton. It is also possible.

The cover canvas 5 is usually made of a plain woven fabric that is stretchable in the longitudinal direction (weft direction) of the belt, but twill woven fabrics and satin woven fabrics can also be used.

In particular, in the case of plain-woven canvas, the warp yarns 5b and weft yarns 5a are alternately stacked vertically, so the warp yarns 5b and weft yarns 5a
The wavy intersections in a are formed continuously in the warp and weft directions, but when twill weave and satin weave canvases are used, the warp and weft yarns form wavy intersections every several warps and wefts, and the intersections are continuous in the warp and weft directions. It has fewer wave-like intersections than canvas, and the rubber penetrates not only between the threads but also between the intersections, and when used in the belt teeth, it avoids direct contact between the warp and weft threads when the belt is bent. , belt life can be improved.

In addition, in order to further increase the stretchability, in addition to the plain weave canvas, twill weave canvas, and satin weave canvas, low-oriented polyester synthetic fiber yarn may be knitted to cover the canvas as a knitted fabric.

The comb compound used for the belt body of the toothed belt is a heat-resistant rubber such as the one described above, such as hydrogenated nitrile rubber, chlorosulfonated polyethylene rubber, alkylated chlorosulfonated polyethylene rubber,
Epichlorohydrin rubber, etc.

In addition, when using a glass fiber cord as the core wire 8, for example, three strands of alkali-free glass filaments each having a diameter of 9μ or 9 to 10μ are bundled together.
Collect the ropes and twist them to a number of first twists of 10.5 to 13.5 times/10cm to make a rope, then collect 18 of these ropes and twist the number of final twists of 6.5 to 9.5 times in the opposite direction to the first twist. /10cm twisted cord, specifically BCG150-3/6
~8/18. The fiberglass cord is RFL treated and overcoated.

Below, specific test examples of the present invention will be listed.

[Test Example 1] As a belt tooth cover canvas for a toothed belt, 6.6 nylon 210 denier × 1 twisted yarn of 15 turns/lQcm was used for the warp, and crimped 40 denier × 6.6 nylon yarn was used for the weft. When using a woven fabric composed of a twill weave structure using five strands of 15 turns/10 cm, the woven fabric was immersed in a pre-treatment liquid of RFL liquid shown in Table 1, and after drying, A cover canvas was obtained by heat-treating at 180° C. for 2 minutes, then immersing it in the rubber glue shown in Table 2, and drying at 220° C. for 1 minute to perform a baking treatment. As a core wire, configuration EC
A bonded glass cord of G150-3/18 with a core wire diameter of approximately 1.2 mm was used.

For the tooth rubber and back rubber, rubber compositions containing hydrogenated nitrile rubber as shown in Table 8 as a main raw material were used.

80℃ at 160℃ using the conventional press-in method using the above materials.
A toothed belt was produced by vulcanization for a minute. The obtained belt had a 5TPD tooth profile with a tooth pitch of 8 mm, the number of teeth was 99, and the belt width was 19.1 mm.

Next, the adhesive force between the obtained cover canvas and tooth rubber was measured. The results are shown in Table 4.

Margin Table 2 Table 2 Molar ratio of resorcin/formalin = 1/2 Weight ratio of RF/L = 1/30) Manufactured by Amania aqueous solution of phenolic condensation polymer *2 Ritakubren FEF carbon black process oil nO Promotion 22 Sulfur Table 3〉:(4〉:ζ5〉:(6):(7〉:(8) Nippon Zeon Co., Ltd. Hydrogenated nitrile rubber N-isopropyl-No-phenyl-P-phenylenediamine dioctyl sebacate tetramethylthiuram disulfide tocyclohexyl-2penlythiazyl nulfenamide Thus, the weight ratio of RFL/chlorophenol is 110. If it is in the range of 03 to 110.1, the adhesive force between the cover canvas and the tooth rubber will be maintained at a high level.

"Test Example 2" In the RFL liquid shown in Table 1, the weight ratio (RF/L) of the initial condensate of resorcin-formalin and the rubber content of latex was varied from 1/1 to 1/40,
and the RFL/chlorophenol weight ratio is 110.05.
A toothed belt was obtained using the same adhesive-treated cover canvas as in Test Example 1 using the first treatment liquid set to .

Next, the obtained belt was run, and the wear rate of the cover canvas and the adhesive force between the cover canvas and the tooth rubber were determined.

The results are shown in Table 5.

In addition, as a method for measuring the wear rate of the cover canvas, we used a driving pulley (20 teeth) and three driven pulleys (each with 2 teeth).
A toothed belt is wound around a device in which idler pulleys (diameter 32 mm) are provided between each pulley, and a load (60 kg) is placed on one driven pulley.
g) to give belt tension. The running conditions are: drive pulley rotation speed 5 + 500 rpm, environmental temperature 120
℃, and the running time was 800 hours. After 800 hours, the thickness of the cover canvas at the bottom of the belt teeth was measured to determine the wear rate.

According to the results, when the weight ratio of RF to L is 10 or more with respect to FtFl, the abrasion resistance of the cover canvas is improved, but the adhesive force between the cover canvas and the tooth rubber is reduced. However, in the case of the present invention in which chlorophenol was added, it can be seen that the rate of decrease is smaller.

[Test Example 3] In this test example, a cover canvas similar to that in Test Example 1 was immersed in the RFL liquid shown in Table 1 and the rubber glue shown in Table 2, and the baking temperature was raised to 160 to 240°C. A rubber reinforcing fiber was obtained by changing the fibers, and this fiber was used as a cover canvas for a toothed belt to obtain a toothed belt similar to Test Example 1.

As a comparative example, a similar toothed belt was obtained by using an RFL liquid shown in Table 1 from which chlorophenol was removed. Table 6 shows the relationship between the adhesive strength between the cover canvas of the toothed belt and the belt teeth and the baking temperature.

According to this, it can be seen that in the rubber reinforcing fiber of the present invention, the adhesive strength increases greatly when the baking temperature is 200° C. or higher, but on the other hand, in the comparative example, the adhesive strength does not increase much even if the baking temperature is increased.

Margin below 4゜ [Effect] In the above invention, untreated fibers are immersed in an RFL liquid in which the weight ratio of RF and L is limited and also contains chlorophenol, and then immersed in rubber glue. By baking at ℃, these rubber reinforcing fibers have improved adhesion to rubber, and also have sufficient reinforcing action for toothed belts used under harsh conditions at high temperatures. This has the effect of further improving the life of the toothed belt used.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional perspective view of a toothed belt according to the present invention, and FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1... Toothed belt Toothed rubber core Back rubber cover Canvas first adhesive layer Second adhesive layer

Claims (1)

[Scope of Claims] 1. A method for adhesion treatment of rubber reinforcing fibers, in which a first treatment liquid of an RFL liquid consisting of resorcinol-formalin-latex is applied to the fibers, and the surface thereof is coated with rubber glue, The molar ratio of resorcin and formalin is 2/1 to 1
/2, and the weight ratio of resorcin-formalin and latex is 1/10 to 1/40, and the RFL liquid contains a solution containing chlorophenol, and the weight ratio of the RFL liquid and chlorophenol is 1/0.03. ~1/0.1 RF
After immersing in L solution, immersing in rubber glue and heating at 200-240℃
1. A method for adhering rubber reinforcing fibers, the method comprising baking at a temperature of . 2. Untreated canvas is treated with RFL in which the molar ratio of resorcin to formalin is 2/1 to 1/2, and the weight ratio of resorcin to formalin to latex is 1/10 to 1/40.
A solution containing chlorophenol is added to the liquid, and the weight ratio of the RFL liquid and chlorophenol is adjusted to 1/0.03 to 1/0.
1. A toothed belt characterized in that the toothed portion of the belt is covered with a cover canvas which has been immersed in the RFL liquid specified in No. 1, coated with rubber glue on its surface, and then baked at 200 to 240°C.