JP3527988B2 - Method for producing twisted aramid fiber cord - Google Patents

Description

BACKGROUND OF THE INVENTION [0001] [Technical Field of the Invention The present invention relates to a process for producing aramid fibers twisted yarn cord having a high strength and high modulus. 2. Description of the Related Art Aramid fibers have a high strength and a high elastic modulus from the beginning and have excellent heat resistance.
Used for ropes, protective clothing, etc. In particular, it is used as a twisted cord in rubber reinforcing materials such as cords and belts. [0003] However, para-aramid fibers, in particular, have a high rigidity, so that there is a problem that the cord strength after twisting is significantly reduced. On the other hand, it is known that twisting is performed with a twist coefficient of 2 or more, and after twisting, a tension heat treatment is performed at a temperature of 100 to 600 ° C. (JP-A-6-136630). [0005] However, Japanese Patent Application Laid-Open No.
In JP 36630, fibers are processed at a high temperature of 200 to 400 ° C. and under high tension, which is disadvantageous in terms of equipment and economy. Further, in the case of polyparaphenylene terephthalamide (PPTA) fiber, improvement in the strength of twisted cord by heat treatment under tension cannot be expected. [0006] On the other hand, the reason why the strength of the twisted cord of para-aramid fiber tends to decrease is that it is difficult to align the yarn or the single fiber. Conventionally, as a means to improve the strength of twisted yarn, an oil agent that reduces friction between fibers has been applied so that uniform twisting is performed. is there. An object of the present invention is to provide a polyparaphenylene terev.
Lies in that provides a means of producing a twisted cord having a high strength using a Taramido (PPTA) textiles. [0008] Means for Solving the Problems That is, the present invention is Repetitive following
Fibers return units (I) 85 A laminating <br/> de system textiles in a by moisture regain more moisture that is configured in mol% is adhered
Under an atmosphere of 100 ° C or less under no tension (official
After drying to a moisture content of -1)% or less, this (official)
In moisture content -1)% or less state, the twist coefficient T is 1.0 to 10
It is a manufacturing method of aramid fibers twisted cord characterized that you are twisted so as to. However, the constitution of the present invention will be specifically described below where T = 0.00348 × the number of twists per 10 cm length × (total yarn fineness) ^1/2 . [0010] aramid textiles of the present invention, an aramid fiber that is configured under Symbol repeating unit (I) 85 mol% or more. [0011] The official moisture content in the present invention is defined by JIS, and for example, the official moisture content of paraphenylene terephthalamide is 6.5%. [0012] twisted in the present invention, a twisted cord, respectively, be twisted yarns the single yarns a plurality of aligning means that Tsu twisted (code). In this case, one yarn may be used, but two or more yarns are preferable. The twist coefficient T in the present invention indicates the strength of twist and is represented by the following equation. [0014] In the T = 0.00348 × twist number × (yarn total denier) per length 10 cm 1/2 present invention, the moisture content of the aramid fibers (percent) (official moisture regain -1)% or less It must be dried in the <br/> shaped on purpose made until there Ru. The moisture content of the fiber維中is
By twisting aramid-based fibers having a (official moisture content of -1)% or less, a twisted yarn structure having high strength can be obtained. The twist coefficient must be 1.0 to 10;
0 to 6.0 is preferred. The total fineness of the yarn used is 1
00 to 10000 denier is preferred. The twisted cord can be prepared by either single twisting or multi-twisting. Particularly preferred is the case of two or more ply yarns. The method for reducing the water content is as follows:
The method is not particularly limited as long as it is performed in the air , and methods such as heat treatment (including far-infrared irradiation) and drying under reduced pressure can be adopted.
In particular, in the case of heat treatment, treatment temperature is 100 ° C. or less under a good better <br/> rather is 70 to 100 ° C.. When the processing temperature is too high tenacity of the yarn is reduced. The yarn at the time of reducing the moisture content is under tension.
And The method of the present invention may be carried out either offline or online. The obtained twisted yarn can maintain its strength by coating the surface and treating with a chemical solution. Hereinafter, the present invention will be described specifically with reference to examples. EXAMPLE 1 Polyparaphenylene terephthalamide (PPTA ) was obtained by the method described in Japanese Patent Publication No. 55-14167.
After that, a fiber consisting of this was made. The yarn used in this Example 1 is a multi-filament yarn of a total denier 1500 denier consisting of 1000 single yarn. The yarn strength is 26 g / d and the breaking elongation is 3
%Met. This yarn was heat-treated at 70 ° C. under a tension-free condition for a predetermined time to obtain yarn samples having different moisture contents. Among them, yarns having the same moisture content
This was prepared, and the two yarns were aligned and twisted 12.7 times per 10 cm to prepare a twisted cord. Incidentally, the official moisture regain of the used yarn is 6.
5%. Table 1 shows the results of the breaking strength of the cords in the tensile test. [Table 1] The twist coefficient T of the twisted cord was calculated to be 2.4. As is clear from Table 1, the water content was 6.5 to 6.5.
At 7.5%, the twist cord strength is 72 kg, but by reducing the water content, the twist cord strength is about 76 kg.
kg. Example 2 The yarn prepared in Example 1 was dried under reduced pressure at room temperature to obtain samples having different moisture contents. Prepare two yarns having the same moisture content, and align these two yarns to 10 cm.
Twisting was performed 12.7 times per time to prepare a twisted cord. Table 2 shows the results of the breaking strength in the tensile test of the cord. [Table 2] As is apparent from Table 2, even without heat treatment, the strength of the twisted cord is improved by reducing the moisture content. Example 3 Two yarns prepared and heat-treated in the same manner as in Example 1 were prepared, and each yarn was twisted 35 times per 10 cm. After that, two yarns were aligned and 35 times per 10 cm in the opposite direction. To give a twisted cord. Table 3 shows the results of the breaking strength in the tensile test of the cord. [Table 3] The twist coefficient T of this twisted cord is calculated to be 6.7. Since the strength of the twist becomes lower as the number of twists becomes higher, the breaking strength of Example 3 is lower than that of Example 1. It can be seen that it has improved. According to the method of the present invention, an aramid fiber twisted cord having excellent strength can be obtained only through a simple process.

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Claims (1)

(57) [Claims] [Claim 1] When the following repeating unit (I) is at least 85 mol%,
Aramid fiber that is composed and exceeds the official moisture content
The fibers to which water has adhered are kept under tension and at 100 ° C or less.
In an atmosphere of, dry until (official moisture content -1)% or less
After drying, twist it in the state of (official moisture content -1)% or less.
Characterized by twisting so that coefficient T is 1.0 to 10
A method for producing an aramid fiber twisted cord. However,
T = 0.00348 × the number of twists per 10 cm length × (Y
1/2 total fineness) 1/2