JP2578561B2 - Processing method of aromatic polyamide fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing method in which aromatic polyamide fibers are used as reinforcing fibers for power transmission belts. In particular, the present invention relates to a belt having a form in which an aromatic polyamide fiber for belt reinforcement is exposed from a side surface of the belt such as a timing belt and a low edge V belt.
When forming a belt by cutting the vulcanized aromatic polyamide fiber reinforced rubber composite in a tubular shape,
The present invention relates to an aromatic polyamide fiber which has been cut and has no single-strand fray of the aromatic polyamide fiber exposed on the end face of the belt, has good adhesion to matrix rubber, and has excellent fatigue resistance.

[0002]

2. Description of the Related Art Aromatic polyamide fibers generally have excellent properties such as strength, elastic modulus, dimensional stability and heat resistance, and are used under severe conditions for rubber composites such as tires, belts and hoses. Useful as an excellent reinforcing fiber. In particular, aromatic polyamide fibers are increasingly expected as lightweight reinforcing fibers replacing steel and wires because of their high specific strength and specific elastic modulus.

In general, when aromatic polyamide fiber is used as a reinforcing fiber for a timing belt or a low-edge V-belt, the aromatic polyamide fiber-reinforced rubber composite formed into a tubular shape and vulcanized is cut into a ring shape by a cutter to form a belt. However, at this time, a single yarn of the aromatic polyamide fiber exposed on the cut surface may protrude from the side surface of the fray or the belt. As a result, the quality of the belt is significantly reduced. If the belt is operated as it is on a pulley, the frayed single yarn portion may be rubbed by the pulley, and the frayed single yarn may be scattered, or the fraying may cause the durability of the belt to decrease.

At present, frayed single yarns are mechanically removed in the belt production process. However, the addition of such an operation significantly reduces the productivity of the belt.
Therefore, single yarn fraying is a major obstacle to adapting aromatic polyamide fibers to this field. On the other hand, in order to improve such disadvantages of the aromatic polyamide fiber, it has been attempted to treat the aromatic polyamide fiber with a treating agent such as rubber latex to prevent fraying of a single yarn at the time of cutting (Japanese Unexamined Patent Publication (Kokai) No. Heisei 9 (1999)). Japanese Patent Application Laid-Open No. 1-207480,
No. 29644), and other drawbacks such as poor twisting properties of the aromatic polyamide fiber, reduced intrinsic strength, and impaired adhesion and durability have not been obtained, and satisfactory results have not been obtained. . The present inventors have also proposed a method in which an aromatic polyamide fiber is treated with a polyepoxide compound, treated with an RFL-containing treating agent, twisted, and further treated with an RFL-based treating agent (Japanese Patent Application No. 4-174216).
And Japanese Patent Application No. 174217/1992), fraying property and adhesiveness are remarkably improved, but there is still room for improvement in fatigue resistance.

[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 an aromatic polyamide fiber for obtaining a power transmission belt which has solved the problems in the prior art. That is, it is an object of the present invention to provide a processing method that prevents fraying of a single yarn of an aromatic polyamide fiber exposed on an end face of a belt during belt formation, improves adhesion to a matrix rubber, and does not reduce fatigue.

[0006]

SUMMARY OF THE INVENTION The present invention provides a method of treating a substantially twisted aromatic polyamide fiber with a first treating agent containing a polyepoxide compound having two or more epoxy groups.
After heat treatment at 50 to 260 ° C. for 30 to 210 seconds, it was treated with a resorcinol / formalin rubber latex (RFL), a silicon-based treating agent and a second treating agent containing an antioxidant or an antioxidant , dried and cured. After, 0.2 ≦ K
≦ 1 ｛K = (T × D ^1/2 ) / 2874, K: Twist coefficient,
T: Twisting number expressed in times / m, D: Twisting treatment within the range of denier と し to form a lower twisted cord, and then combining a plurality of the lower twisted cords in the same twisting direction as the lower twisted cord. 1 ≦ K ≦ 5
A method for treating an aromatic polyamide fiber, comprising twisting within the range of the above and further treating with a treatment agent containing RFL. ".

The aromatic polyamide fiber in the present invention is a para-based aromatic polyamide fiber, a meta-based aromatic polyamide 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,
Although a 2,5-pyridylene group and the like can be mentioned, a 1,4-phenylene group is preferable. The aromatic ring includes, for example, a halogen group (eg, chlorine, bromine, fluorine), a lower alkyl group (methyl group, ethyl group, isopropyl group, n-propyl group), a lower alkoxy group (methoxy group, ethoxy group), a cyano group, An acetyl group, a nitro group, or the like may be included as a substituent.

Specific examples include polyparaphenylene terephthalamide (Kevlar manufactured by DuPont), polymetaphenylene isophthalamide (Co-nex manufactured by Teijin Limited), polyparaaminobenzamide, poly-3,4
It is a fiber comprising '-oxydiphenylene terephthalamide / polyparaphenylene terephthalamide copolymer (such as Technora manufactured by Teijin Limited), polyparaaminobenzhydrazide terephthalamide, and the like.

[0010] The aromatic polyamide fiber is treated with a first treating agent containing a polyepoxide compound that is substantially untwisted and contains two or more epoxy groups. Substantially untwisted means a non-twisted state in which the treating agent of the present invention can sufficiently adhere to each of the single fibers, and even if twisted, adheres to the same degree as untwisted. Means what can be done. The polyepoxide compound is a compound having at least two or more epoxy groups in one molecule, ethylene glycol,
Glycerol, sorbitol, pentaerythritol,
Reaction products of polyhydric alcohols such as polyethylene glycol with halogen-containing epoxides such as epichlorohydrin, and polyhydric phenols such as resorcinol bis (4-hydroxyphenyl) dimethylmethane, phenol-formaldehyde resin and resorcinol-formaldehyde resin A polyepoxide compound obtained by oxidizing an unsaturated compound with a reaction product with the halogen-containing epoxide or peracetic acid or hydrogen peroxide, that is, 3,4-epoxycyclohexene epoxide, 3,4-epoxycyclohexylmethyl-3, 4-epoxycyclohexene carboxylate, bis (3,4-epoxy-6-methyl-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. Polyepoxide compounds are amine-based,
It is possible to use a mixture of a blocked polyisocyanate, which is an addition compound of an imidazole-based curing agent or polyisocyanate and a known oxime, phenol, or a blocking agent such as caprolactam, or ethylene urea, which is a reaction compound with ethylene imine described below. it can.

A polyepoxide compound (A) and a curing agent,
The mixing ratio with the blocked polyisocyanate or ethylene urea (B) is 0.05 ≦ (A) / [(A) +
(B)] ≦ 0.9 (weight ratio) is preferable. The concentration of the polyepoxide compound is preferably from 0.1 to 5.0%.
The total solids concentration is preferably from 1 to 30% by weight, particularly preferably from 3 to 20% by weight.

The above-mentioned first treating agent containing the polyepoxide compound is usually mixed with an oil agent in the step of producing aromatic polyamide fibers and adhered to the fibers, or after the production of aromatic polyamide fibers, the first treatment agent is separated from the fiber-forming step. Attached in the process. The solid content on the aromatic polyamide fiber is 0.05 to
5.0% by weight is preferred. 60-1 at 100-150 ° C
Dry for 80 seconds and then at 150-250 ° C for 30-21
Heat treatment for 0 seconds. Preferably, it is 60 to 180 seconds.

The aromatic polyamide fiber treated with the polyepoxy compound is subsequently treated with a second treating agent (adhesive) containing RFL, dimethylpolysiloxane and an antioxidant or an antioxidant. RFL preferably has a molar ratio of resorcinol to formaldehyde of 1: 0.1 to 1:
8, more preferably from 1: 0.5 to 1: 5, particularly preferably from 1: 1 to 1: 4. The compounding ratio of resorcinol-formalin and rubber latex is preferably 1: 1 to 1:15, more preferably 1: 3 to 1 in terms of solid content weight ratio.
1:12. If the compounding ratio of the rubber latex is too high, the tackiness is remarkably increased and the cohesive force is reduced, and the twisting property
Adversely affects adhesion. 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 rubber type of the adherend. For example, if the adherend rubber is chloroprene (CR), CR latex,
For NBR or H-NBR, NBR latex or H
-NBR latex is used. For chlorosulfonated polyethylene (CSM), CSM latex is often used. Of course, a mixed compound mainly composed of these rubber latexes may be used.

The addition amount of the silicon-based treating agent is preferably 0.5 to 5.0% by weight based on the RFL. The silicon-based treating agent used here has a group represented by the following formula (Chemical Formula 1)
And a group represented by the following formula (Formula 2) as a repeating unit
Is a polysiloxane. Typical silicon treatment agent
Is a methyl group in which R ₁ is a methyl group and R ₂ is a hydrogen atom.
Le hydrogen polysiloxane or R ₁ and R ₂
List dimethylpolysiloxane which is a methyl group
Can be. Molecular weight of silicon-based treating agent depends on the type of substituent
Therefore, for example, when R ₁ and R ₂ are methyl groups,
In this case, the range of 1
000 or less is preferable.

[0016]

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[0017]

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The amount of the antioxidant or antioxidant added is preferably from 0.1 to 3.0% by weight. The type of antioxidant is preferably a hindered phenol-based, amine-based, phosphorus-based or sulfur-based compound. Representative examples of hindered phenol compounds include triethylene glycol bis [3- (3-t-butyl-6-methyl-4-hydroxyphenyl) propionate] and 1,6-hexanediol-bis [3 -(3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis-
(N-octylthio) -6- (4-hydroxy-3,5
-Di-t-butylanily-1,3,5-triazine, pentaerythrityl-tetrakis [3- (3,5-di-t
-Butyl-4-hydroxyphenyl) propionate], 2,2-thio-diethylenebis [3- (3,5-
Di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, N, N '
-Hexamethylenebis (3,5-di-t-butyl-4-
Hydroxy-hydroxycinnamamide), 1,3,5-
And trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene.
Hindered phenol compounds containing sulfur or phosphorus in the molecule include 2,2-thiobis (4-methyl-6-t-butylphenol) and 3,5-di-t-butyl-4-hydroxybenzylphospho. Nate-diethyl ester and the like. Representative examples of amine antioxidants include N,
N′-di-sec-butyl-p-phenylenediamine,
And alkylated diphenylamine.

Examples of the antioxidant include an aldehyde-amine reaction product, and a typical example thereof is a condensate of aldol and 1-naphthylamine. 2,2,4-trimethyl- as a ketone-amine reaction product
It is a 1,2-dihydroquinoline polymer. N, N'-dinaphthyl-p-phenylenediamine is a typical example of the amine compound. Phenol compounds include styrenated phenol, 2,6-di-t-butylmethylphenol, 2,2′-methylenebis (4-methyl-6-t-butylphenol), and 4,4′-thiobis (3-methylphenol). -6-t-butylphenol).

After treating with RFL, dimethylpolysiloxane and a second treating agent containing an antioxidant or an antioxidant, drying at 80 to 150 ° C. for 0.5 to 5 minutes,
Heat-treat at 150-260 ° C for 0.5-5 minutes to cure. The amount of RFL attached to the aromatic polyamide fiber in the second treatment agent is preferably 1 to 25% by weight, and more preferably 5 to 20% by weight. If the amount is less than 1% by weight, the single yarn exposed from the belt end face may be frayed when used as a reinforcing fiber of the power transmission belt. If the content is more than 25% by weight, the strength utilization rate at the time of twisting the treated aromatic polyamide fiber is low, and the strength is not sufficiently exhibited.

The aromatic polyamide fiber treated with the polyepoxide compound and then with the RFL, dimethylpolysiloxane and the second treating agent containing an antioxidant or an antioxidant and then dried and heat-treated is successively added with 0.2 ≦ K ≦ 1
(K = (T × D1 / 2) / 2874, K: twist coefficient, T: number of twists expressed in turns / m, D: denier) A plurality of wires are twisted in the same direction as the lower twisted cord in the range of 1 ≦ K ≦ 5,
We twist. Twisted aromatic polyamide fiber cord is further treated by RFL (resorcinol / formalin latex)
Is treated with a third treating agent (adhesive) containing. RFL, like RFL as the second treating agent, preferably has a molar ratio of resorcinol to formaldehyde of 1: 0.1 to 1: 8,
It is more preferably used in the range of 1: 0.5 to 1: 5, particularly preferably in the range of 1: 1 to 1: 4. The mixing ratio of resorcinol-formalin and rubber latex is preferably 1: 1 to 1:15, more preferably 1: 3 to 1 in terms of solid content weight ratio.
1:12. The type of the rubber latex is selected according to the rubber latex used for the RFL of the second treating agent. An ethylene urea compound represented by the following general formula (Formula 3)

[0022]

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Alternatively, a blocked polyisocyanate obtained by reacting an aromatic or aliphatic isocyanate with an oxime, phenol, caprolactam or the like may be used in addition (see Japanese Patent Publication No. 57-21587). 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. Further, an aqueous dispersion of carbon black prepared by an ordinary method may be added in an amount of 0.5 to 5% by weight based on RFL. After the treatment with RFL, it is also preferable to further treat with a rubber paste containing the same type of rubber as the rubber matrix of the adherend. After treatment with RFL, drying at 80-150 ° C. for 0.5-5 minutes, 150-
Heat treat at 260 ° C for 0.5-5 minutes to cure. The amount of RFL attached to the twisted cord is adjusted to 1 to 10% by weight.

[0024]

After the aromatic polyamide fiber is thus treated with a polyepoxide compound containing two or more epoxy groups (first treating agent), RFL, dimethylpolysiloxane and an antioxidant or antioxidant are added. Second including
After treating with a treating agent and then drying and heat-treating, apply a priming twist to a predetermined number of twists, further apply a plurality of priming cords, apply ply twisting in the same direction as the priming cord, and further treat with RFL It is possible to prevent single yarn fraying from the end face of the aromatic polyamide fiber reinforced power transmission belt, and to improve the adhesive force with the matrix rubber to significantly increase the fatigue resistance. The reason why the anti-fraying property is improved is that the epoxide compound and RFL react with each other to form a film having a high cohesive force and flexibility. It is presumed to adhere. It is also considered that dimethylpolysiloxane improves the twisting property by lowering the frictional property and increases the cord strength. In addition, in advance, a low twist cord having a low twist coefficient is prepared, a plurality of the low twist cords are combined, and the upper yarn is twisted in the same direction to improve the alignment of the single yarns, thereby increasing the cord strength. At the same time, it is considered that elongation / compression strain during fatigue is uniformly dispersed, which leads to remarkable improvement in fatigue resistance. Further, an antioxidant or an antioxidant added to the RFL may be used while the belt is running.
It is presumed that L hardens and the aromatic polyamide fiber as a reinforcing fiber is prevented from becoming hard, which leads to an improvement in fatigue resistance. The aromatic polyamide fiber treated by the method of the present invention has a small decrease in strength, does not cause fraying of a single yarn from the belt end face after forming the power transmission belt, and has good adhesion to the matrix and fatigue resistance. It is.

Hereinafter, the present invention will be described specifically with reference to examples.

In the examples, cord strength, fraying property, cord peeling adhesive strength, pull-out adhesive strength, and strength retention during fatigue were determined by the following methods.

<Cord Strength> Using an Intesco 2005 type tensile tester (manufactured by Intesco Corporation), a cord length was set to 250 mm between the chucks using a 4D air chuck.
Tensile speed 100 mm / min. Was used to measure the cord strength. The measurement was performed five times, and the average value was defined as the code strength.

<Fasting> Rubber sheet 2 about 2 mm thick
Aromatic polyamide cords treated by the method of the present invention are sandwiched between the sheets in parallel and sandwiched at 50 ° C. for 30 minutes at 150 ° C.
Vulcanization was performed at a pressing pressure of / cm ² to obtain a rubber sheet. This sheet was cut with a cutter knife so that the end face of the cord appeared on the cut surface. Then, the state of the single yarn of the aromatic polyamide fiber projecting from the end face was visually determined. Also, the end face is rubbed with sandpaper (# AA-150),
The frayed state of the single yarn was observed. Evaluation is good ◎ → ○ → △ →
X (bad).

<Cord Peeling Adhesive Strength> This shows the peeling adhesive strength between the treated cord and the rubber. 7 cords are buried near the surface of the rubber sheet, and 50
Vulcanization was performed with a pressing pressure of kg / cm ² , then the two cords at both ends were removed, and the remaining five cords were removed from the rubber sheet at 200 mm / min. The force required to peel at a speed of kg / 5
Displayed in the book.

<Pull-out adhesive strength> This shows the shear adhesive strength between the treatment cord and rubber. Embed the cord in a rubber block and pressurize at 150 ° C under pressure for 30 minutes, 50kg / c
vulcanized in a press pressure of m ^2, then the code from the rubber block 200 mm / min. And the force required for the drawing was expressed in kg / cm 2.

<Strength of retention during fatigue> This is a scale representing fatigue resistance. Using a belt-type fatigue tester, sandwich the cord between two rubber sheets with a thickness of 2 mm, at 150 ℃ for 30 minutes,
A sheet obtained by vulcanizing under a pressing pressure of 50 kg / cm ² was cut into a belt shape having a width of 50 mm and a length of 500 mm, a load of 25 kg was applied, and the sheet was attached to a roller of 20 mmφ.
After reciprocating at 120 rpm in an atmosphere of 20 ° C. and repeating 500,000 times, the cord was taken out, the residual strength was measured, and the strength retention during fatigue was determined.

[0032]

Example 1, Comparative Examples 1 to 3 First, the first treating agent and the second treating agent were prepared. That is, 14.5 g of Denacol EX-313 (glycerin diglycidyl ether; manufactured by Nagase Kasei Co., Ltd.) and 14.5 g of Neocol SW-30 (dioctyl sulfosuccinate sodium salt; manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as a surfactant are added. Stir and dissolve. Then water
The above epoxy solution was slowly added to 656.2 g while stirring at a high speed, and dispersed. The obtained mixture was used as a first treating agent.

In addition, sodium hydroxide was added to 202.2 g of water.
Add 6.4 g of a 10% aqueous solution and 18.8 g of a 28% ammonia aqueous solution, stir well, and further react with an acidic catalyst to obtain a 40% acetone solution of the resorcinol-formalin initial condensate.
39.5 g was added and sufficiently stirred and dispersed. Then water 278.
To 0 g, 400.7 g of Nippol LX-1562 (41% aqueous emulsion of acrylonitrile-butadiene copolymer rubber latex; manufactured by Zeon Corporation) was mixed with slow stirring.
The above-mentioned resorcinol-formalin initial condensate dispersion was mixed with the mixed solution while slowly stirring, and 16.4 g of a 37% formalin aqueous solution was further added and mixed. 30 g of a 20% aqueous dispersion of dimethylpolysiloxane (molecular weight 400) and a hindered phenolic antioxidant (Irganox 10
10; manufactured by Ciba-Geigy Co., Ltd.). The resulting mixture having a concentration of 20% was used as a second treating agent.

An aromatic polyamide fiber (Technola; manufactured by Teijin Limited) 1500 denier / 1000 filaments was immersed in the first treatment agent using a computer treater (tire code processor manufactured by CA Ritzler). , Dried at 130 ° C for 2 minutes and subsequently heat-treated at 235 ° C for 1 minute. Next, it is immersed in the second treatment agent, dried and heat-treated under the same conditions as the first treatment agent, and the treated raw yarn is twisted in the S direction at a twist coefficient of 0.4 (3 times / 10 cm) to obtain The obtained two twisted cords were combined and twisted in the S direction at a twist factor of 2 (10.5 turns / 10 cm).

Next, the twisted cord is set to RFL (R / F =
1 / 2.5 molar ratio, RF / L = 1/5 weight ratio, L = acrylonitrile-butadiene copolymer rubber latex; Nipol LX1562, manufactured by Nippon Zeon Co., Ltd.), and the adhesion rate to the twisted cord is 5 weight. %, Dried at 130 ° C. for 2 minutes, 240 ° C. for 2 minutes,
It was cured by heat treatment under tension.

The strength of the obtained treated cord was measured, and it was then arranged in parallel on an H-NBR-compounded rubber sheet having a thickness of about 2 mm. 50 kg / cm for 30 minutes at ℃
Vulcanization was performed at a pressing pressure of ² to obtain a rubber sheet. This sheet was cut with a cutter knife so that the end face of the cord appeared on the cut surface. Then, the state of the single yarn of the aromatic polyamide fiber projecting from the end face was visually determined. Further, the end face was rubbed with sandpaper (# AA-150) to observe the frayed state of the single yarn. Evaluation is (good) ◎ → ○ → △ → ×
(Poor) was determined. Further, peel adhesion, pull-out adhesion, and fatigue strength by a belt fatigue tester were measured. Table 1 shows the results.

A cord obtained in the same manner as in Example 1 except that an antioxidant was added to the second treating agent and dimethylpolysiloxane was not added was used in Comparative Example 1, and dimethylpolysiloxane was added and an antioxidant was added. A cord obtained in the same manner as in Example 1 except that no cord was obtained was referred to as Comparative Example 2, and a cord obtained in the same manner as in Example 1 except that both the antioxidant and dimethylpolysiloxane were not added was referred to as Comparative Example 3. did. Table 1 shows the results.

[0038]

[Table 1]

As apparent from Table 1, the aromatic polyamide fiber was treated with a polyepoxide compound (first treating agent),
Cords treated with RFL, dimethylpolysiloxane, a second treating agent containing antioxidant, then twisted, then twisted, and further treated with RFL have high strength and markedly improved fatigue resistance And has good frayability and adhesiveness.

[0040]

Example 2, Comparative Examples 4 to 6 The polyepoxide treating agent as the first treating agent was adjusted in the same manner as in Example 1. Further, the RFL of the second treating agent was adjusted to the NBR latex by Nipol 2518FS (vinyl pyridine styrene
Butadiene latex 41% water emulsion; manufactured by Nippon Zeon Co., Ltd.). In addition, after performing both the lower twist and the upper twist in the same manner as in Example 1, it was treated with the RFL containing Nipol 2518FS used as the second treating agent.

Comparative Example 4 was carried out in the same manner as in Example 1 except that an antioxidant was added to the second treating agent and dimethylpolysiloxane was not added. Except that dimethylpolysiloxane was added and no antioxidant was added. For each of Comparative Example 5 carried out in the same manner as in Example 1 and Comparative Example 6 carried out in the same manner as in Example 1 except that both the antioxidant and dimethylpolysiloxane were not added, the flaws of the treatment codes obtained were as follows. , Peel adhesion, pull-out adhesion, and fatigue resistance were measured. The rubber used CR compound rubber. Table 2 shows the obtained results.

[0042]

[Table 2]

As is clear from Table 2, even when the type of the latex is changed, it is clear that the material exhibits extremely good fatigue resistance, fraying property and adhesiveness.

Claims (2)

(57) [Claims] 1. A substantially untwisted aromatic polyamide fiber is treated with a polyepoxide compound-containing first treating agent having two or more epoxy groups, and is treated at 150 to 260 ° C. for 30 to 30 minutes.
After heat treatment for 210 seconds, resorcinol / formalin / rubber latex (RFL), silicon-based treating agent and antioxidant
After treating with a second treating agent containing a blocking agent or an anti-aging agent , drying and curing, 0.2 ≦ K ≦ 1 ｛K = (T ×
D ^1/2 ) / 2874, K: Twisting coefficient, T: Twisting number expressed in times / m, D: Twisting treatment within the range of denier と し to give a sub-twisted cord. A method for treating aromatic polyamide fibers, comprising: twisting a plurality of fibers together in the same twisting direction as the lower twisted cord within a range of 1 ≦ K ≦ 5, and further treating with a treatment agent containing RFL. 2. The silicon treatment agent having a molecular weight of 1,000 or less.
The method for treating an aromatic polyamide fiber according to claim 1, which is dimethylpolysiloxane below .