JPS63152470A - Production of fiber for reinforcing rubber - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method for producing rubber reinforcing fibers used for reinforcing rubber products such as rubber belts and tires.

(Prior Art) Reinforcing fibers such as glass fiber yarn are widely used to increase the strength of rubber products such as rubber belts and tires.

Rubber products such as rubber belts are subject to repeated bending stress, resulting in bending fatigue and reduced performance. Peeling occurs between the reinforcing material and the rubber matrix, or the reinforcing fibers wear out, resulting in a decrease in strength. In order to prevent such peeling and obtain a sufficient reinforcing effect, it is necessary to increase the compatibility and adhesive strength between the reinforcing fibers and the rubber, and for this purpose, a treatment agent is applied to the surface of the reinforcing fibers.

Recently, toothed belts have come to be used in place of chains to drive the camshafts of automobiles, but with longer life due to maintenance-free operation and higher output due to the adoption of turbocharging, high performance belts are now in demand.

Treatment agents of various compositions have been proposed, or the bonding strength between the reinforcing agent and the rubber matrix is large, resulting in a decrease in strength even when subjected to repeated stress, or peeling between the reinforcing fibers and the rubber matrix. There is no known processing agent that does not cause heat loss and has sufficient heat resistance.

For example, processing agents using a combination of a terpolymer latex of vinyl-gin-styrene-tutadiene and a water-soluble condensate of resorcinol and formaldehyde, or processing agents such as NBR (acrylonitrile, butadiene rubber), 5BR (styrene, phtadiene rubber), CR (chloroprene rubber), etc. Various processing agents have been proposed, such as processing agents containing rubber latex.

(Refer to Japanese Patent Application Laid-Open No. 114551/1983) It is said that the bonding force (adhesive force) between the reinforcing material and the rubber matrix can be sufficiently increased by using such a treatment agent, but when subjected to repeated bending stress, the strength It can be degraded or reinforced with fibers and rubber mud.

It is difficult to obtain high-performance belts as described above because they tend to peel off during the liquefaction process, shorten the service life, have low heat resistance, and easily wear out the reinforcing material, resulting in a decrease in strength. could not.

This tendency is particularly remarkable when used for reinforcing heat-resistant rubbers with low adhesion such as chloroprene rubber, chlorosulfonylated polyethylene, and hydrogenated nitrile rubber.

(Problems to be Solved by the Invention) The present invention aims to solve the above-mentioned drawbacks of the prior art.

[Structure of the Invention] (Means for Solving the Problems) The present invention has been made to solve the above-mentioned problems. The present invention provides a method for producing rubber reinforcing fibers, which comprises treating the fibers with a second liquid containing an adhesive and then drying them.

Next, the present invention will be explained in more detail.

Examples of the fluororesin latex include polytetrafluoroethylene latex, Te1-rafluoroethylene-propylene copolymer latex, polyhexafluoropropylene latex, and particularly favorable results are obtained when polytetrafluoroethylene latex is used. You can wander around.

The concentration of latex is 20-50 wt%, preferably 25
A suitable concentration is ~40 wt%; if this concentration is too low, sedimentation of latex particles may occur or the amount of adhesion to Fa fibers is likely to be insufficient.

Moreover, if this concentration is too large, the amount of adhesion to am tends to be excessive.

In the present invention, the reinforcing am to be treated with the first liquid is not particularly limited, but it is practical to use glass fiber. For example, by adding a sizing agent to glass fiber with a thickness of 9IL,
It is preferable to use a bundle of about 0 glass fibers in three rows. Although there is no particular limitation on the means for treating the reinforcing fibers with the first liquid, it is practical to continuously supply the reinforcing fibers and pass them through an impregnation tank filled with the first liquid. can be impregnated uniformly. The amount of the first liquid to be added to the reinforcing fibers is 10 to 10% of the reinforcing fibers as a solid content.
It is appropriate to set the amount to 25 wt%, preferably 14 to 22 wt%; if this amount is too small, the effect of the present invention will not be sufficient, and if this amount is too large, separation of the rubber matrix and reinforcing m fibers may easily occur. Become.

Prior to treatment with the second liquid, the reinforcing fibers treated with the first liquid are dried to form a fluororesin layer on the reinforcing fibers.

Next, the second liquid will be explained.

As the second liquid containing an adhesive, a fluororesin adhesive gives particularly favorable results, and is exemplified by RB-20 (trade name, manufactured by Toyo Kagaku Kenkyuko Co., Ltd., solid content: 40 wt%).

The concentration of the second liquid of the present invention mentioned above is 5 to 20%, preferably 7
It is appropriate to set it to 14%.

If the concentration is too low, the adhesion resistance to the reinforcing fibers will be insufficient, and if the concentration is too high, uneven adhesion will likely occur.

The first liquid is applied, dried, and treated with the second liquid. Although there are no limitations on the treatment means, it is practical to continuously supply the reinforcing fibers and pass them through an impregnating tank filled with the second liquid. Prior to treatment with the second liquid, 2.54
It is appropriate to give S or Z twists of about 1 to 4 times per cm, align them by about 2 to 13 times, and give twists in the opposite direction (ply twist) of about 1 to 4 times per 2.54 cm.

The amount of the second liquid applied is 2 to 8 wt of the weight of the reinforcing fiber as solid content.
%, preferably 3 to 5 wt%; if this amount is too small, the effect of the present invention will not be sufficient, and if this amount is too large, the fibers will become too thick.

The reinforcing fibers to which the second liquid has been applied are dried at 100 to 3000C, preferably 150 to 2506C. The time required for drying is determined depending on the drying temperature, etc., but is usually 5 to 120 seconds.
ec, and it is appropriate that the solvent content be 0.3 wt% or less. By completely drying in this manner, the components contained in the first liquid and the second liquid contained in the mixed layer are firmly bonded and integrated, and no peeling occurs. Furthermore, since a surface layer made of only the components of the second liquid is formed on the surface, compatibility with the rubber matrix is improved.

There are no particular limitations on the type of rubber to be reinforced with the reinforcing fibers of the present invention, but extremely favorable results can be obtained even when used with Hypalon, nitrile rubber, hydrogenated nitrile rubber, etc., and the fibers have excellent heat resistance and durability. Reinforced rubber products such as timing belts with good properties can be obtained.

(Function) Since the reinforcing fibers are treated and dried with the first liquid containing fluororesin latex, a fluororesin layer is formed on the surface, which reduces friction between the fibers or between the fibers and the rubber matrix. A friction-reducing effect occurs. Further, by applying a second liquid containing an adhesive onto the dried fluororesin layer and drying, the two are firmly bonded and no peeling occurs.

Furthermore, since a surface layer consisting only of the second liquid is formed on the surface, it is compatible with the rubber matrix.

(Example) A glass fiber bundle consisting of 200 glass fibers of 9 strands was arranged with 3 threads and given a Z twist of 2.54 c +++ times, and polytetraethylene latex (trade name: AD-1,
Manufactured by Asahi Glass, latex content 60wt%) 333gr,
After passing continuously through a first tank filled with a liquid consisting of 2gr A-11002g and 170gr water, it was heated for 20 seconds in an oven maintained at 270°C.

The adhesion resistance amount of the fluororesin was 18 wt% of the reinforcing fiber.

The fibers were aligned with 13 threads, given 2.1 S twists (ply twists) per 2.54 cm, and then passed through a second tank filled with RB-20, and then placed in an oven maintained at 250°C. Heated for 20 seconds.

The amount of the second liquid component attached was 3 wt% based on the reinforcing fibers.

A test piece was prepared using the fiber thus obtained as a reinforcing fiber.

50 parts by weight of carbon fluff per 100 parts by weight of rubber type H-NBR
parts by weight, 5 parts by weight of zinc white, 0.5 parts by weight of stearic acid,
Contains 4 parts by weight of Mg0, 8 parts by weight of plasticizer, 3 parts by weight of anti-aging agent, and 3 parts by weight of vulcanization accelerator.

Specifications of Test Piece Two of the above reinforcing fibers were sandwiched between rubber sheets with a thickness of 1 mm, a width of 5+ am, and a length of 300 mm, pressed, and vulcanized at 160° C. for 20 minutes.

This test piece was left in an oven at 140°C for 24 hours, and then subjected to bending stress 3,000 times using an MIT tester.
The tensile strength of the test piece after being applied 20,000 times was measured, and the rate of decrease in strength was determined. The results are shown in the attached table.

(Comparative example) Vinylpyridine, styrene and butadiene at 15:15
Vinylpyridine-styrene-butadiene terpolymer latex (Pyratex trade name, manufactured by Sumitomo Naugatuck Co., Ltd., terpolymer content 4)
1 wt%), 65 parts by weight, butadiene latex (07
00, Product name, Japan Synthetic Rubber, Butadiene content 5
7 wt%), 8 parts by weight, and an aqueous solution containing 20 wt% of an addition condensate of resorcin and formaldehyde (resol).
To a mixture of 5 parts by weight and 12 parts by weight of water, 1 part by weight of a mineral oil emulsion (mineral oil content 55 wt%) and 1 part by weight of ammonia water (concentration 18 wt%) as anti-aging agents were added. Used in place of the first liquid in the example, the adhesion resistance was 18
The same test as in the example was conducted using wt%.

The results are shown in the attached table.

Test results

Claims (1)

[Claims] (1) A method for producing rubber reinforcing fibers, which comprises treating the fibers with a first liquid containing a fluororesin latex and drying the fibers, and then treating the fibers with a second liquid containing an adhesive and drying the fibers.