JPH08284069A - Production of aramid fiber for reinforcing power transmission belt - Google Patents

Abstract

PURPOSE: To provide a method for producing aramid fibers for reinforcing power transmission belts without decreasing fatigue of the belts by protecting frayings of filaments exposed on the end surface of the belt during a belt formation. CONSTITUTION: This method for producing an aramid fiber for reinforcing power transmission belts is to pretreat essentially nontwisted plural aramid fiber yarns with a first treating agent containing a polyepoxide compound containing more than two epoxy groups, doubling twist the yarns in the range of 1<=K<=5 [K=(T×D<1/2> )/2874, K is a twisting factor; T is a twisting number in turns/m; D is a finesse in denier] while adding a second treating agent containing a resorcinol formalin rubber latex compound(RFL), a silicone-based compound and a deterioration proofing agent, then treat the yarns with a third treating agent containing the RFL after heat treating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aramid fiber for reinforcing a power transmission belt. In particular, the present invention relates to a belt such as a timing belt or a low edge V-belt, in which aramid fibers for belt reinforcement are exposed from the side surface of the belt.

[0002]

BACKGROUND ART Aramid fibers generally have excellent properties such as strength, elastic modulus, dimensional stability, and heat resistance, so that they are excellent for rubber composites such as tires, belts and hoses used under severe conditions. It is useful as a reinforcing fiber. In particular, because of its high specific strength and high specific elastic modulus, aramid fiber is increasingly expected as a lightweight reinforcing fiber instead of steel or wire.

Generally, when aramid fiber is used as a reinforcing fiber for a timing belt or a low edge V-belt, the aramid fiber reinforced rubber composite molded into a tubular shape and vulcanized is cut with a cutter into a circular slice to form a belt. At that time, each single yarn of the aramid fiber exposed on the cut surface may be frayed and protrude from the side surface of the belt. As a result, the quality of the belt is significantly reduced. 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 the frayedness deteriorates the durability of the belt.

At present, the unraveled single yarn is mechanically removed in the belt production process, but the productivity of the belt is remarkably lowered by the addition of such work. Therefore, single yarn fray is a major obstacle to adapting aramid fiber to this field. On the other hand, in order to improve such a defect of the aramid fiber, it has been attempted to treat the aramid fiber with a treating agent such as rubber latex to prevent the single yarn from being frayed at the time of cutting (JP-A-1-207480). JP-A-4-29644, JP-A-6-25977), and other drawbacks such as poor twistability of aramid fibers, reduction in original strength, and loss of adhesiveness and durability. There is also a possibility that a satisfactory result is not obtained.

[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 prevent fraying of a single yarn of aramid fiber exposed on the belt end surface during belt molding,
It is an object of the present invention to provide a method for producing aramid fibers for reinforcing a power transmission belt, which does not reduce fatigue of the belt.

[0006]

According to the present invention, "(Claim 1) Resorcinol-formalin is formed on a plurality of substantially untwisted aramid fibers pretreated with a polyepoxide compound-containing first treating agent containing two or more epoxy groups.・ Rubber latex compound (R
FL), a silicon-based compound, and a second treatment agent containing a deterioration inhibitor while applying 1 ≦ K ≦ 5 (K = (T × D ^1/2 ).
/ 2874, K; twist coefficient, T; twist number, number of turns / m, D; fineness, denier), after twisting the fibers together, heat treating, and further treating with a third treating agent containing RFL. A method for producing an aramid fiber for reinforcing a power transmission belt. (Claim 2) The method for producing an aramid fiber for reinforcing a power transmission belt according to claim 1, wherein the amount of the second treatment agent attached is 1 to 30% by weight. (Claim 3) The deterioration inhibitor is an antioxidant.
Alternatively, the method for producing an aramid fiber for reinforcing a power transmission belt according to 2). (Claim 4) The deterioration preventing agent is an antiaging agent.
Alternatively, the method for producing an aramid fiber for reinforcing a power transmission belt according to 2). ".

Here, the aramid fiber is a para-aramid fiber, a meta-aramid fiber, or a copolymer thereof.

Examples of the aromatic ring include 1,4-phenylene group, 1,3-phenylene group, 4,4'-biphenylene group, 1,5 naphthylene group, 2,6 naphthylene group,
A 2,5-pyridylene group and the like can be mentioned, but a 1,4-phenylene group is preferable. Aromatic rings include, for example, halogen groups (eg chlorine, bromine, fluorine), lower alkyl groups (methyl group, ethyl group, isopropyl group, n-propyl group), lower alkoxy groups (methoxy group, ethoxy group), cyano group, acetyl group. A group, a nitro group or the like may be contained as a substituent.

Specific examples include polyparaphenylene terephthalamide (Kevlar manufactured by Dyupon Co., Ltd.), polymetaphenylene isophthalamide (Conex manufactured by Teijin Ltd., etc.), polyparaaminobenzamide, poly-3,4'-oxydiphenylene. A fiber composed of a terephthalamide copolymer (such as Technora manufactured by Teijin Ltd.) and polyparaaminobenzhydrazide terephthalamide.

The aramid fiber is pre-treated with the first treatment agent, but it is preferable that the aramid fiber is attached and treated in a substantially non-twisted state.
The term "substantially untwisted" means an untwisted state in which the first treating agent can be sufficiently attached to each single fiber, and even if twisted, it can be sufficiently attached to the same degree as untwisted. Means a state. A polyepoxide compound is a compound having at least two epoxy groups in one molecule, and is formed by reaction of polyhydric alcohols such as ethylene glycol, glycerol, sorbitol, pentaerythritol, and polyethylene glycol with halogen-containing epoxides such as epichlorohydrin. Compounds, reaction products of polyhydric phenols such as resorcin / bis (4-hydroxyphenyl) dimethylmethane, phenol / formaldehyde resins, resorcin / formaldehyde resins with the halogen-containing epoxides, peracetic acid or hydrogen peroxide, etc. A polyepoxide compound obtained by oxidizing an unsaturated compound, that is, 3,4-epoxycyclohexene epoxide, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexene carboxylate, Scan (3,4 epoxy-6-methylstyrene over cyclohexylmethyl) adipate, and the like. Of these, a reaction product of a polyhydric alcohol and epichlorohydrin, that is, a polyglycidyl ether compound of a polyhydric alcohol is particularly preferred because of excellent performance.

Such a polyepoxide compound is usually dissolved in a small amount of a solvent and used as an emulsion or solution using a known emulsifier, for example, sodium alkylbenzenesulfonate, sodium salt of dioctylsulfosuccinate. Ethylene urea, which is an addition compound of an amine-based or imidazole-based curing agent or polyisocyanate with a known blocking agent such as oxime, phenol, or caprolactam, can be mixed and used in the polyepoxide compound.

The mixing ratio of the polyepoxide compound (A) to the imidazole type curing agent, blocked polyisocyanate or ethylene urea (B) is 0.05 ≦ (A) /
The range of [(A) + (B)] ≦ 0.9 (weight ratio) is preferable. The concentration of the polyepoxide compound dispersion is 0.1-5.
0% by weight is preferred. The total solid content concentration is preferably 1 to 3.
It is 0% by weight, particularly preferably 3 to 20% by weight.

The first treating agent containing a polyepoxide compound is usually mixed with an oil agent in the aramid fiber spinning process to adhere to the fiber, or after the aramid fiber is spun,
Although it is attached in a step different from the yarn making step, the method of attaching the first treatment agent is not limited. The solid content of the first treatment agent with respect to the aramid fiber is preferably 0.05 to 5.0% by weight. After the adhesion treatment, 60-18 at 100-150 ° C
Dry for 0 seconds, then 30-210 at 150-260 ° C
Heat treat for seconds. Preferably, it is 60 to 180 seconds.
The drying and heat treatment may be performed before the second treatment agent application treatment or after the second treatment agent application treatment.

A plurality of substantially untwisted aramid fibers treated with a polyepoxy compound are adhered with a second treating agent (adhesive) containing RFL, dimethylpolysiloxane and an antioxidant or an antioxidant. However, 1 ≦ K ≦ 5
(K = (T × D ^1/2 ) / 2874, K; twist coefficient, T; twist number, times / m, D; fineness, denier), after being twisted in the range of 30 to 300 at 150 to 260 ° C. It is heat-treated for 2 seconds and further treated with a treatment agent containing RFL (third treatment agent). Here, RFL is used in a molar ratio of resorcin and formaldehyde of preferably 1: 0.5 to 1: 5, particularly preferably 1: 1 to 1: 4. The compounding ratio of resorcin / formalin and rubber latex is preferably 1: 1 to 1:15 by weight of solid content, more preferably 1: 3 to 1: 1.
Twelve. If the compounding ratio of the rubber latex is too high, the tackiness is remarkably increased and the cohesive force is lowered, which adversely affects the adhesiveness. Conversely, if the compounding ratio of the rubber latex is too low, the cord becomes hard, and the strength and the fatigue are reduced. The type of rubber latex is selected according to the type of rubber of the adherend. For example, if the adherend rubber is chloroprene (CR), CR latex is used, or NBR or H-
In the case of NBR, NBR latex or H-NBR latex is used. For chlorosulfonated polyethylene (CSP), CSP latex is often used. Of course, a mixed compound mainly composed of these rubber latexes may be used.

The amount of the silicon compound added is preferably 0.5 to 5.0% by weight based on RFL. Further, the addition amount of the antioxidant or the antioxidant is preferably 0.1 to 3.0% by weight. The type of antioxidant is hindered phenol type,
Amine-based, phosphorus-based and sulfur-based compounds are preferred. As the antiaging agent, an aldehyde / amine reaction product or the like is used.

The amount of RFL attached to the aramid fiber is
It is 1 to 30% by weight, preferably 1 to 25% by weight. If the adhered amount is less than 1% by weight, the single yarn exposed from the belt end surface may be frayed when used as a reinforcing fiber of a power transmission belt. On the other hand, if it is more than 35% by weight, the treating agent is scattered during continuous burning of the yarn, resulting in deterioration of working environment. It is preferable to use a metering oiling nozzle or an oiling roller to attach the second treatment agent to the fibers in terms of quantitativeness.

The aramid fiber is twisted while being treated with a second treatment agent containing RFL, dimethylpolysiloxane and an antioxidant or an antioxidant, and then 150 to 260 ° C.
And heat-treat for 30 to 300 seconds to cure.

In this way, the first treating agent containing the polyepoxide compound is pretreated, and then the second treating agent containing RFL, dimethylpolysiloxane and the antioxidant or the antiaging agent is applied, and then the twisting treatment is carried out. The heat-treated aramid fiber cord is further treated with a third treatment agent (adhesive) containing RFL (resorcin / formalin / rubber latex compound). Similar to RFL used in the second treatment agent, RFL has a molar ratio of resorcin and formaldehyde of preferably 1: 0.1 to 1: 8, more preferably 1: 0.5 to 1: 5, and particularly preferably 1 : 1-1: 1
Used in the range of 4. The mixing ratio of resorcin-formalin and rubber latex is preferably 1: 1 to 1:15, more preferably 1: 3 to 1:12 in terms of solid content weight ratio. The type of rubber latex is selected according to the rubber latex used for the second processing agent RFL. This R
A blocked polyisocyanate obtained by reacting an ethylene urea compound or an aromatic or aliphatic isocyanate oxime, phenol, caprolactam, or the like may be added to FL and used (JP-B-57-2158).
(See Japanese Patent Publication No. 7). The ethylene urea compound is usually added in the form of an aqueous dispersion in an amount of 0.5 to 30% by weight based on RFL. It is also preferable that the aqueous dispersion of carbon black prepared by a usual method is further treated with a rubber paste containing the same kind of rubber as the rubber matrix of the adherend. After the treatment with RFL, it is heat-treated at 150 to 260 ° C. for 30 to 300 seconds to be cured. The amount of RFL attached to the twisted cord is 1
Adjust to -10% by weight.

[0019]

As described above, the treatment agent containing the polyepoxide compound containing two or more epoxy groups (first treatment agent).
The aramid fiber pre-treated with 1. was twisted within the range of 1 ≦ K ≦ 5 while applying a treatment agent (second treatment agent) containing RFL, dimethylpolysiloxane and an antioxidant or an antioxidant. After that, heat treatment and further treatment with a treatment agent containing RFL (third treatment agent) can prevent single yarn fraying from the end face of the power transmission belt reinforced with aramid fibers, and prevent the occurrence of matrix rubber. To improve the adhesive strength and significantly improve fatigue resistance. The reason why the prevention of fraying is improved is that the epoxide compound and the RFL react with each other to form a film having high cohesive force and flexibility, and each aramid fiber single yarn is covered to firmly It is presumed that this is for bonding. In addition, it is considered that dimethylpolysiloxane improves the twisting property by lowering the friction property and enhances the cord strength. Also R
It is presumed that the antioxidant or anti-aging agent added to the FL prevents the RFL from hardening during the running of the belt and hardening the aramid fiber as the reinforcing fiber, which leads to the improvement of fatigue resistance. The aramid fiber according to the present invention has a small decrease in tenacity, does not cause a single yarn fray from the belt end surface after forming a power transmission belt, and has good adhesiveness to a matrix and fatigue resistance.

Examples will be described below. In the examples, the cord strength, the frayability, the cord peeling adhesive force, the pulling adhesive force, and the fatigue strength retention were determined by the following methods. <Cord Strength> Using an Intesco 2005 type tensile tester (manufactured by Intesco), a cord length is set to 250 mm between chucks using a 4D air chuck, and a pulling speed of 10
The cord strength was measured at 0 mm / min. Measured 5 times,
The average value was used as the code strength. <Frayability> Aramid cords treated by the method of the present invention are arranged in parallel between two rubber sheets having a thickness of about 2 mm and vulcanized by applying a pressing pressure of 50 kg / cm ² at 150 ° C. for 30 minutes. Then, a rubber sheet was obtained. 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 evaluation was (good) ⊚➝➝Δ➝ × (defective). <Cord peeling adhesive strength> This shows the peeling adhesive strength between the treated cord and rubber. Seven cords were buried near the surface of the rubber sheet, and vulcanized at 150 ° C for 30 minutes with a pressing pressure of 50 kg / cm ² , then the two cords at both ends were removed and the remaining 5 cords were removed. 20 from the rubber sheet
The force required for peeling at a speed of 0 mm / min is kg /
Displayed with 5 lines. <Pull Out Adhesive Strength> This shows the shear adhesive strength between the treated cord and the rubber. Embed the code in the rubber block,
It is vulcanized by pressurizing at 150 ° C. for 30 minutes with a pressing pressure of 50 kg / cm ² , and then the cord is removed from the rubber block 2 times.
It was drawn at a speed of 00 mm / min, and the force required for the drawing was expressed in kg / cm. <Strength retention during fatigue> It is a scale showing fatigue resistance. A belt type fatigue tester was used. 2mm thick rubber sheet 2
Put the cord between the sheets, 150kg for 30 minutes, 50kg
The sheet obtained by pressurizing and vulcanizing with a press pressure of / cm ² is cut into a belt shape of 50 mm width × 500 mm length and the load is 2
Apply 5kg and attach it to a roller with a diameter of 20mm.
It was reciprocated at 120 rpm in an atmosphere of 0 ° C. Fifty
After repeating 10,000 times, the cord was taken out and the residual strength was measured to determine the strength retention rate during fatigue.

[0021]

Examples 1 to 3 and Comparative Examples 1 and 2 First, the first treating agent and the second treating agent were prepared.

That is, Denacol EX-313 (glycerin diglycidyl ether; manufactured by Nagase Kasei Co., Ltd.) 1
To 7.5 g, 14.5 g of Neocol SW-30 (sodium salt of dioctyl sulfosuccinate; manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) as a surfactant was added and well mixed by stirring. Then, the above epoxy solution was slowly added to 656.2 g of water while stirring at high speed to disperse. The obtained mixed liquid was used as the first treatment agent.

In addition, 202.2 g of water contained 6.4 g of a 10% aqueous sodium hydroxide solution and 1% of a 28% aqueous ammonia solution.
40 g of resorcinol-formalin initial condensation product obtained by adding 8.8 g, stirring sufficiently, and further reacting with an acidic catalyst
% Acetone solution (39.5 g) was added and sufficiently stirred to disperse. Next, add Nipol LX-1 to 278.0 g of water.
562 (Acrylonitrile-butadiene copolymer rubber latex 41% water emulsion; manufactured by Nippon Zeon Co., Ltd.) 40
0.7 g was mixed with slow stirring. The above resorcinol-formalin initial condensate dispersion was mixed into this mixed solution with slow stirring, and 16.4 g of a 37% aqueous formalin solution was added and mixed. 30 g of a 20% aqueous dispersion of dimethylpolysiloxane (molecular weight 400) and a hindered phenolic antioxidant (Irganox 10
10; 25% aqueous dispersion of Ciba-Geigy Co., Ltd.) 8 g
Was added. The obtained mixed solution having a concentration of 20% was used as the second treatment agent.

After immersing 1500 denier / 100 filaments of aramid fiber (Technora; manufactured by Teijin Ltd.) in the first treatment agent using a computer treating machine (tire cord processing machine manufactured by CA Ritzler Co., Ltd.), 130 Dry at 120 ° C for 120 seconds and continue at 235 ° C for 6 seconds.
Heat treatment was performed for 0 seconds. Using a twisting machine equipped with a measuring oiling nozzle device, the obtained aramid fiber is attached with the second treating agent by a measuring oiling nozzle,
Two 1500 denier / 1000 filament fibers were twisted in the S direction with a twist coefficient of 2 (3 times / 10 cm). The obtained adhesive-attached cord was taken out and dried and heat-treated under the same conditions as the first treatment agent. At this time, the adhesion amounts of the second processing agent (adhesive) are 1.6, 15.5, and 2, respectively.
It was 4.7% by weight (Examples 1 to 3).

Then, twist the twisted cord attached with the adhesive to R
FL (R / F = 1 / 2.5, RF / L = 1/5 weight ratio,
L = acrylonitrile-budadiene copolymer rubber latex; manufactured by Nihon Zeon Co., Ltd., Nipol LX156
2), adjusted so that the adhesion rate to the twisted cord is 5% by weight, and dried at 130 ° C. for 120 seconds, then 24
It was cured by heating under tension at 0 ° C. for 120 seconds.

The strength of the obtained adhesive treatment cord was measured,
Then, it is arranged on an H-NBR compounded rubber sheet having a thickness of about 2 mm, and a similar H-NBR compounded rubber sheet is further laid on the cord, and the pressure is 50 kg / cm for 30 minutes at 150 ° C.
^A rubber sheet was obtained by hot pressing with a pressing pressure of ² and vulcanization.
This sheet was cut in the lengthwise direction so that the cord end surface 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. Evaluation is (good) ◎ → ○ → △ → ×
(Poor) was determined.

Further, using the above-mentioned method, the peeling adhesive force,
The pull-out adhesive strength and the strength during fatigue were measured by a belt fatigue tester. The results of Examples 1 to 3 are shown in Table 1.

Aramid fiber (Technora; manufactured by Teijin Ltd.) 1500 denier / 100 filaments was treated with the first treatment agent under the same conditions as in Examples 1 to 3, and two fibers (1500 denier / 1000 filament) were obtained. Was twisted with a twisting machine at a twisting coefficient of 2 (3 times / 10 cm), a second treating agent was attached to the cord, and subsequently heat treated under the same conditions as in Examples 1 to 3 The code obtained by performing the treatment with the third treatment agent under the same conditions as above was set as Comparative Example 1. A code obtained under the same conditions as in Examples 1 to 3 was used as Comparative Example 2 except that the amount of the second treatment agent attached was 0.8% by weight. The results of Comparative Examples 1 and 2 are also shown in Table 1.

As is clear from Table 1, in Examples 1 to 3, the first treating agent and the second treating agent were sufficiently adhered to each single yarn of the fiber, so that the frayability was good. It turns out that On the other hand, in Comparative Example 1, since the second treatment agent does not penetrate into the inside of the twisted cord, the frayability is poor. Further, in Comparative Example 2, the amount of the second treatment agent attached was too small, so that the fraying property was insufficient. Examples 1 to 3 employ the method of ply twisting while adhering the second treatment agent to the substantially non-twisted fiber, so that the damage of the fiber due to the friction between the single fibers during the twisting is extremely high. It can be seen that it is very small and shows good results in terms of cord strength, fatigue resistance, and adhesiveness.

[0030]

[Table 1]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location // B29K 67:00 (72) Inventor Atsushi Watanabe 3-4-1, Mihara, Ibaraki-shi, Osaka Teijin Incorporated company Osaka Research Center

Claims (4)

[Claims] 1. A plurality of substantially untwisted aramid fibers pretreated with a first treatment agent containing a polyepoxide compound containing two or more epoxy groups, and resorcin formalin.
1 ≦ K while applying a second processing agent containing a rubber latex compound (RFL), a silicon compound and a deterioration inhibitor
≦ 5 (K = (T × D ^1/2 ) / 2874, K; twist coefficient,
T: number of twists, turns / m, D: fineness, denier) After twisting the fibers in the range, heat treatment, and further treatment with a third treatment agent containing RFL for reinforcing a power transmission belt Method for producing aramid fiber. 2. The method for producing an aramid fiber for reinforcing a power transmission belt according to claim 1, wherein the amount of the second treatment agent attached is 1 to 30% by weight. 3. The deterioration preventing agent is an antioxidant.
Alternatively, the method for producing an aramid fiber for reinforcing a power transmission belt according to 2). 4. The deterioration preventing agent is an antiaging agent.
Alternatively, the method for producing an aramid fiber for reinforcing a power transmission belt according to 2).