JPH08199484A - Treatment of aramid yarn - Google Patents

Abstract

PURPOSE: To provide a method for treating aramid yarn, capable of preventing fray of single yarn of aramid yarn exposing to the end face of a belt during forming a belt, improved in adhesiveness between aramid yarn and a matrix and exhibiting excellent fatigue resistance. CONSTITUTION: Aramid yarn is twisted under conditions of 0.2<=K<=1 [K=(T×D1/2)2874, K: a twist coefficient, T: the number of twists shown by times/m, D: fineness of single yarn). Then the prepared plural first twist cords are Joined, twisted in the same direction as that of the first twist cords under conditions of 1<=K<=5, passed through a pressurized treating agent comprising a polyepoxide compound containing two or more epoxy groups, dried at 100-150 deg.C for 0.5-5 minutes, heat-treated at 150-260 deg.C for 0.5-5 minutes, treated with a treating agent containing a resorcin/formalin/ruber latex(RFL), dried at 80-150 deg.C for 0.5-5 minutes, heat-treated at 150-260 deg.C for 0.5-5 minutes and cured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a treatment method when aramid fiber is used as a fiber for reinforcing a power transmission belt. In particular, the present invention is a belt having a form in which the aramid fiber for belt reinforcement is exposed on the side surface of the belt, such as a timing belt or a low edge V belt, and cuts a vulcanized aramid fiber reinforced rubber composite into a tubular shape. When molded into a belt by cutting into a shape, the single yarn of aramid fiber exposed on the end face of the belt cut in the axial direction of the fiber is not frayed, the adhesiveness with the matrix rubber is good, and the fatigue resistance is excellent. A method for treating aramid fibers.

[0002]

2. Description of the Related Art Generally, aramid fiber has excellent strength, elastic modulus, dimensional stability, heat resistance, etc., so that it is excellent for rubber composites such as tires, belts and hoses used under severe conditions. It is useful as a reinforcing fiber. In particular, aramid fiber is increasingly expected as a lightweight reinforcing fiber instead of steel or wire because of its high specific strength and specific elastic modulus.

Generally, when aramid fiber is used as a reinforcing fiber for a timing belt or a low edge V-belt, a belt is prepared by cutting a vulcanized aramid fiber reinforced rubber composite, which has been formed into a tubular shape in advance, into a circular slice with a cutter. Although it is molded, the aramid fiber single yarn exposed on the cut surface may be frayed or protrude on the side surface of the belt, in which case the quality of the belt is significantly deteriorated. If the belt is driven as it is on the pulley, the single yarn frayed portion is rubbed by the pulley, and the frayed single yarn scatters, or this fraying causes the durability of the belt to deteriorate.

These drawbacks are prevented by the work of mechanically removing or cutting the above-mentioned frayed single yarns in the process of producing the belt. The productivity was significantly reduced, which was a major obstacle to adapting aramid fiber to this field. Attempts have been made to treat the aramid fiber with a treating agent such as rubber latex to prevent the single yarn from being frayed during cutting (JP-A-1-207480, JP-A-4-29644). Satisfactory results have not been obtained because other defects may occur, such as poor properties, reduced original strength, and impaired adhesiveness and durability.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for treating aramid fibers to obtain a power transmission belt that solves the problems of the prior art, that is, during belt molding. It is an object of the present invention to provide a treatment method for preventing fraying of a single yarn of aramid fiber exposed on the end surface of a belt and for preventing deterioration of fatigue resistance.

[0006]

According to the present invention, "(Claim 1) Aramid fiber is 0.2≤K≤1 (K = (T × D1 / 2) / 2874,
K: twist coefficient, T: number of twists expressed in turns / m, D: single yarn fineness) within a range of twisting treatment, and then a plurality of these twisted cords are combined in the same direction as the twisted cords. Twisted within the range of 1 ≦ K ≦ 5, and then passed through a pressure treatment agent containing a polyepoxide compound containing two or more epoxy groups,
Dry at 00-150 ° C for 0.5-5 minutes, then 150
After heat treatment at ~ 260 ° C for 0.5 to 5 minutes, it is treated with a treating agent containing resorcin / formalin / rubber latex (RFL), dried at 80 to 150 ° C for 0.5 to 5 minutes, and
A method for treating aramid fibers, which comprises heat treating at 50 to 260 ° C. for 0.5 to 5 minutes to cure. (Claim 2) The method for treating aramid fibers according to claim 1, wherein the pressure range is 3 to 200 kg / cm ² . ".

The aramid fiber in the present invention is a fiber made of a polymer in which an aromatic ring is bound by an amide bond and the repeating unit accounts for at least 80% of the whole. Typical examples of fibers made of these polymers or copolymers include polyparaphenylene terephthalamide, polymetaphenylene isophthalamide, polyparaphenylene-3,3.
Fibers made of conventionally known aramid such as 4'diphenyl ether / terephthalamide can be mentioned.

The aramid fiber is first of 0.2 ≦ K ≦ 1 (K
= (T × D1 / 2) / 2874, K; twist coefficient, T; times / m
In the range of 1 twist K, D; single yarn fineness), a plurality of lower twist cords are combined, and in the same direction as the lower twist cord, within a range of 1 ≦ K ≦ 5. Perform twisting process. The twisting machine used is not particularly limited.

Then, the twisted aramid fiber is passed through a pressure-treating agent containing a polyepoxide compound containing two or more epoxy groups to give the aramid fiber.
From the surroundings, a substantially uniform pressure is applied to the treatment.

The polyepoxide compound has at least two epoxy groups in one molecule.
A compound containing 0.2 g equivalent or more per g, and a reaction product of a polyhydric alcohol such as ethylene glycol, glycerol, sorbitol, pentaerythritol, or polyethylene glycol with a halogen-containing epoxide such as epichlorohydrin, resorcin bis (4 -Hydroxyphenyl) dimethylmethane, phenol / formaldehyde resin, resorcin / formaldehyde resin, and other reaction products of polyphenols and halogen-containing epoxides, obtained by oxidizing unsaturated compounds with peracetic acid or hydrogen peroxide A polyepoxide compound, namely, 3,4-epoxycyclohexene epoxide, 3,
4-epoxycyclohexylmethyl-3,4-epoxycyclohexenecarboxylate, bis (3,4-epoxy-6-methyl-cyclohexylmethyl) adipate and the like can be mentioned. Among these, in particular, the reaction product of a polyhydric alcohol and epichlorohydrin, that is,
Polyglycidyl ether compounds of polyhydric alcohols are preferable because they show excellent performance.

The treating agent containing the polyepoxide compound was filled in a pressure resistant container having a fiber supply port, a fiber take-out port, and a treating agent supply port, and the pressure treatment agent containing the polyepoxide compound was subjected to the above twisting treatment. By running the aramid fiber, the treatment is performed while applying a substantially uniform pressure from the periphery thereof.

The treatment method is performed by supplying the treatment agent pressurized by a pressure pump from the treatment agent supply port of the pressure resistant container. At this time, the treatment agent leaks from the fiber supply port and the fiber take-out port, but in order to reduce the leakage amount of the treatment agent, as shown in FIG. 1, the gap between the twisted yarn cord and the fiber supply port and the twisted yarn cord and the fiber It is preferable that the clearance between the processing agent can be adjusted, or, as shown in FIG. 2, the treatment agent be recovered by providing a substantially fluid expansion chamber at the fiber supply inlet and the fiber outlet.

[0013] The pressure because it is preferable to be 3~200kg / cm ^2, less a processing agent than the pressure 3 kg / cm ² does not penetrate into the twisted yarn cord, not sufficient fray preventing effect is obtained, also If it is higher than 200 kg / cm ^{2, the} effect of preventing fraying can be obtained, but it is necessary to increase the capacity of the pressurizing pump and the like, which causes difficulties in equipment and causes a safety problem.

The aramid fiber was pressure-treated with a treating agent containing the above polyepoxide compound, dried at 100 to 150 ° C. for 0.5 to 5 minutes, and then at 150 to 260 ° C. for 0.
After heat treatment for 5 to 5 minutes, treat with a treatment agent containing resorcin / formalin / rubber latex (RFL),
It is dried at 150 ° C. for 0.5 to 5 minutes and heat-treated at 150 to 260 ° C. for 0.5 to 5 minutes to be cured. The amount of the second treatment agent RFL attached to the aramid fiber is preferably 1 to 10% by weight.

In this way, a predetermined number of twists of the aramid fiber are twisted, a plurality of twisted twisted cords are further twisted, and the twisted twisted cords are twisted in the same direction. It is passed through a treatment agent containing two or more polyepoxide compounds. By treating the aramid fiber from its periphery while applying a substantially uniform pressure, and further by treating with the RFL, it is possible to prevent the single yarn from fraying from the end face of the aramid fiber reinforced power transmission belt, and Of course, the adhesive strength with the matrix rubber is improved,
Fatigue resistance is remarkably improved. To improve the prevention of fraying, the epoxide compound and RFL react with each other to form a relatively flexible film with high cohesive force, and at the same time, each aramid fiber single yarn is coated with one RFL to make it strong. It is presumed that the fray resistance will be improved because of adhesion to the. Also, create a lower twist cord with a small twist coefficient,
By twisting the same in the same direction, it is possible to improve the alignment of the single yarns, improve the cord strength, and evenly stretch and compressive strain during fatigue to disperse the stress, leading to a significant improvement in fatigue resistance. To be

[0016]

EFFECTS OF THE INVENTION The aramid fiber treated by the method of the present invention has a small decrease in strength, and after forming the power transmission belt, does not cause fray of the aramid fiber single yarn from the end face of the belt, and has excellent adhesiveness to the matrix. Fatigue is also good.

The present invention will be specifically described below with reference to examples. In the examples, the frayability, the cord peeling adhesive force, the pulling adhesive force, the fatigue strength retention rate, etc. are values determined as follows.

<Frayability> A rubber sheet 2 having a thickness of about 2 mm
The aramid cords subjected to the above-mentioned fraying treatment are arranged in parallel between the sheets and sandwiched at 150 ° C. for 30 minutes, 50 kg / cm.
Vulcanization was performed at a pressing pressure of ² to obtain a rubber sheet. This sheet was cut with a cutter knife in the length direction of the cords arranged in the rubber so that the end faces of the cords appeared on the cut surface. Then, the state of the single yarn of the aramid fiber protruding from the end face was visually determined. Further, this end face was rubbed with sandpaper (# AA-150), and the state of fraying of the single yarn was observed. The results were evaluated as (good) ⊚➝➝Δ➝ × (defective).

<Cord Peeling Adhesive Strength> This shows the peeling adhesive strength between the treated cord and the rubber. Fill 7 cords near the surface of the rubber sheet, 150 ℃, 30 minutes, 50kg
Vulcanized at a pressing pressure of / cm ² and then the two cords at both ends were removed and the remaining 5 cords were removed from the rubber sheet at a speed of 200 mm / min. The force required for peeling with kg /
It is displayed with five lines.

<Pull Out Adhesive Strength> This shows the shear adhesive strength between the treated cord and the rubber. The cord was embedded in a rubber block and vulcanized at a pressing pressure of 50 kg / cm ² at 150 ° C. for 30 minutes, and then the cord was removed from the rubber block 2
00 mm / min. And the force required for drawing is displayed in kg / cm.

<Fatigue strength retention> This is a measure of fatigue resistance. 2mm thickness using belt type fatigue tester
Insert the cord between two sheets of rubber sheet at and
A sheet obtained by vulcanizing at a pressing pressure of 50 kg / cm ² for 0 minutes was cut into a belt shape of 50 mm width × 500 mm length, a load of 25 kg was applied, and the sheet was attached to a roller having a diameter of 20 mm, under an atmosphere of 120 ° C. After reciprocating at 120 rpm and repeating 500,000 times, the cord was taken out and the residual strength was measured to determine the strength retention rate during fatigue.

[0022]

Examples 1 to 3 and Comparative Examples 1 and 2 First, the adhesive treatment agent was prepared as follows. That is, 17.5 g of Denacol EX-313 (glycerin diglycidyl ether; manufactured by Nagase Kasei Co., Ltd.) was added to Neocor SW-3 as a surfactant.
0 (dioctyl sulfosuccinate sodium salt; manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) (14.5 g) was added, and the mixture was stirred well and dissolved. Then, while stirring 656.2 g of water at high speed, the above epoxy solution is slowly added and dispersed. The resulting blended liquid is used as the first treatment agent.

Also, in 134.8 g of water, 4.4 g of 10% aqueous sodium hydroxide solution and 28% aqueous ammonia solution 2.
8 g was added and sufficiently stirred, and further, 26.9 g of resorcin-formalin initial condensate (40% acetone solution) obtained by reacting with an acidic catalyst was added and sufficiently stirred to disperse.

Next, in water 416.7, Nipol LX-1
562 (Acrylonitrile-butadiene copolymer rubber latex 41% water emulsion; manufactured by Nippon Zeon Co., Ltd.) 27
3.2 g is slowly stirred and mixed, and 11.2 g of formalin (37%) is further added and mixed. The compounded liquid thus obtained is used as the second treatment agent.

Aramid fiber (Technora, manufactured by Teijin Ltd.) 1500 denier / 1000 filament was twisted in the S direction with a twist coefficient of 0.4 (3 times / 10 cm), and two lower twist cords were combined and further S was added. Twist factor 2 (1
Twisted 0.5 times / 10 cm). The code obtained is
Using a computer treating machine (tire cord processing machine manufactured by CA Ritzler Co., Ltd.), the pressurized first treating agent is passed through, dried at 130 ° C. for 2 minutes, and then heat treated at 235 ° C. for 1 minute. did. Here, the pressurization was performed by mounting the device shown in FIG. 2 on a computer treating machine and pressurizing it, and changing the pressurizing condition. Next, it was immersed in the second treatment agent, dried and heat-treated under the same conditions as the first treatment agent.

The obtained adhesive-treated cord was applied to a 2 mm thick hydrogenated acrylonitrile-butadiene rubber (H-N).
(BR) compounded rubber sheet is arranged in parallel, and the same H-NBR compounded rubber sheet is overlaid on the cord, and
It was vulcanized at 0 ° C. for 30 minutes under a pressing pressure of 50 kg / cm ² to obtain a rubber sheet.

The resulting rubber sheet was measured for frayability, peel adhesion, pullout adhesion, and fatigue strength by a belt fatigue tester. The results are shown in Table 1.

As is apparent from the table, in Examples 1 to 3, it is found that the frayability is good. On the other hand, in Comparative Example 1, since the pressure applied by the first treatment agent was low, the first treatment agent did not permeate into the inside of the twisted cord, and the frayability was insufficient. Further, Comparative Example 2 is an example in which a high capacity pressurizing pump is used, and thus the load on the process becomes large, and there is a problem in process control.

[0029]

[Table 1]

[Brief description of drawings]

FIG. 1 shows an example of a pressure device used in the method of the present invention.

FIG. 2 is another example of a pressure device used in the method of the present invention.

[Explanation of symbols]

 1 Pressure-resistant container 2a, 2b, 2c, 2d Fluid expansion chamber 3a, 3b Fiber passage port 4 Fiber supply port 5 Fiber extraction port 6 Treatment agent supply port 7a, 7b Elastic body 8 Twist cord

Claims (2)

[Claims] 1. An aramid fiber having 0.2 ≦ K ≦ 1 (K =
(T × D1 / 2) / 2874, K; twisting coefficient, T; twist number expressed in times / m, D: single yarn fineness) within a range of twisting treatment,
Then, a plurality of these twisted twisted cords are combined and twisted in the same direction as the twisted twisted cords within a range of 1 ≦ K ≦ 5, and then in a pressure treatment agent containing a polyepoxide compound containing two or more epoxy groups. Through 0.5 to 5 at 100 to 150 ° C
After drying for 15 minutes and then heat treatment at 150 to 260 ° C for 0.5 to 5 minutes, it is treated with a treatment agent containing resorcin / formalin / rubber latex (RFL) and dried at 80 to 150 ° C for 0.5 to 5 minutes. 0.5 to 5 at 150 to 260 ° C
A method for treating aramid fibers, which comprises heat-curing for minutes to cure. 2. The method for treating aramid fibers according to claim 1, wherein the pressure range is 3 to 200 kg / cm ² .