JPH0364630B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for dramatically improving the light resistance of aromatic polyamide fibers. This particularly relates to the field of clothing that requires light resistance. PRIOR ART Fully aromatic polyamides are known to be suitable for a wide range of applications. It has a higher softening point and melting point than aliphatic polyamides (e.g. nylon-6, nylon-6,6, etc.), and has excellent strength retention at high temperatures, shape stability, heat resistance such as thermal decomposition, flame resistance, and difficulty. It not only has excellent flammability, but also has extremely desirable physical and chemical properties such as chemical resistance, electrical properties, and mechanical properties such as strength and Young's modulus, and is heat resistant, flame retardant, and flame retardant. Suitable for applications such as fibers, high strength and high Young's modulus fibers, and film molding materials. For example, it can be used as an electrical insulating material for motors, transformers, etc., as a filter bag,
It is widely accepted in industrial applications such as heating tubes and other non-aesthetic textiles. On the other hand, in textile textiles for which trendy colors are considered important, they are mainly used as heat-resistant safety clothing in aviation uniforms, firefighting work uniforms, etc. In addition, rayon, cotton wool, wool, etc. are blended and knitted,
By adding functions such as sweat absorption, moisture absorption, and heat retention to the high mechanical performance of aromatic polyamide, efforts are being made to expand into the fields of sportswear and comfortable clothing that can be worn even under heavy duty conditions. As mentioned above, light fastness has traditionally been a major barrier to development in the clothing field. (Objective of the Invention) The object of the present invention is to obtain a fabric having excellent light fastness while retaining as much as possible the excellent properties of aromatic polyamide fibers. Conventionally, in order to improve the light resistance of aromatic polyamide fibers, there is a method of mixing ultraviolet absorbers during dyeing, but since this fiber is inherently difficult to dye, the diffusivity of the ultraviolet absorbent within the fibers is low and the results are satisfactory. can't get it. Further, even if a carrier is used as an adsorption promoter, the ultraviolet absorber is not sufficiently introduced into the fiber, and no effect of improving light resistance is observed. In view of the current situation, the present inventors have studied a method for improving the light resistance of aromatic polyamide fibers more effectively than before, and have arrived at the present invention. (Structure and operation of the invention) That is, the present invention is "a method for improving the light resistance of aromatic polyamide fibers, which is characterized by heat-treating aromatic polyamide fibers in the coexistence of urea and thiourea." The aromatic polyamide fiber in the present invention has the general formula

[Formula] and/or

It consists of a repeating unit represented by the formula: In the above general formula, R ₄ , R ₂ and R ₃ may be the same or different and are selected from hydrogen atoms and alkyl groups having 5 or less carbon atoms. Examples of the alkyl group having 5 or less carbon atoms include methyl group, ethyl group, propyl group, butyl group, and pentyl group, but preferably a hydrogen atom. Furthermore, Ar ₁ , Ar ₂ and Ar ₃ may be the same or different, and the general formula and/or and/or and/or and/or −Ar′− ...(5). In general formulas (1) and (2), -X- is -O-, -S
-,

It is a group selected from [Formula]. -X- and preferably -O-,

[Formula] is selected, more preferably -O-. In general formulas (3) and (4), -Y- is -O-, -S-, _-SO2- , _-CH2- ,

【formula】 【formula】 【formula】

Selected from [formula]. (R represents an alkyl group having 5 or less carbon atoms as described above.) -Y- is preferably -O
-, -S-,

[Formula] is selected, more preferably -O-. In general formulas (1), (2), (5)
Ar and Ar' may be the same or different and are selected from coaxially oriented aromatic rings. Coaxially or parallelly oriented aromatic rings include, for example, 1,4-phenylene group,
Examples include 1,3-phenylene group, 4,4'-biphenylene group, 1,5-naphthylene group, 2,6-naphthylene group, 2,5-vinydylene group, and 1,4-phenylene group is preferred. base, 1,
A 3-phenylene group is chosen. Examples of preferable aromatic polyamides used in the present invention include Polyamide consisting of Polyamide consisting of Polyamide consisting of Polyamide consisting of Polyamide consisting of Polyamide consisting of Polyamide consisting of Examples include polyamide made of. In addition, the benzene ring in the skeletons (1) to (5) and the above-mentioned aromatic ring residues include, for example, halogen groups (e.g. chlorine, bromine, fluorine), lower alkyl groups (methyl, ethyl, isopropyl), etc. , n-propyl group), lower alkoxy group (methoxy, ethoxy group), cyano group, acetyl group, nitro group, etc. as a substituent. Here, a method for applying a mixture of urea and thiourea to aromatic polyamide fibers will be described in detail below. It is effective in improving light resistance only when urea and thiourea coexist, and no effect is observed when treated with urea or thiourea alone. When applying a mixture of urea and thiourea to an aromatic polyamide fabric, it is effective whether it is applied in the form of a powder or a solution, but if it is applied in a solution form, it must be patted and then squeezed with a mangle, etc. Alternatively, it is applied to the fabric by spraying or the like and then dried. When applied in solution, the concentration of the urea and thiourea mixture can range from 1 to 100% by weight, but is particularly preferably from 20 to 80% by weight. Also, the mixing ratio (weight ratio) of urea and thiourea is
It is effective in the range of 80:20 to 20:80, but particularly remarkable effects are observed at ratios of 70:30 to 50:50. The pH of the solution may be within the range of 3 to 10. The drying temperature may be within the range of 80 to 130°C. PH
When the pH is less than 3 and when the pH exceeds 10, decomposition of urea or thiourea occurs. Next, heat treatment (curing) is performed, and the curing conditions are a temperature of 160 to 210° C. and a treatment time of 30 seconds to 5 minutes. Particularly preferred is 180-190°C for 1-2 minutes. Under conditions milder than this, the effect of improving light resistance is small, and under conditions more severe than this, the aromatic polyamide fibers turn brown and have a hard texture, making them unsuitable for practical use. The aromatic polyamide of the present invention may be an aromatic polyamide made of a polyamide copolymer having a functional group having affinity with dyes in the polymer chain. As described above, the effect of the present invention is particularly large when an aromatic polyamide whose dyeability is improved by the third component is used. This is thought to be because the deactivation reaction of amino groups takes place more effectively inside the fiber. Furthermore, the aromatic polyamide fiber targeted by the present invention may be undyed (fiber after scouring and setting),
It may be dyed with ionic dyes such as acid dyes and cationic dyes, or nonionic dyes such as disperse dyes and threne dyes. Furthermore, it may contain colored pigments. Furthermore, the present invention is not limited to aromatic polyamide fibers alone, but also blends and cross-spun fibers with other synthetic fibers (fibers made of polyester, aliphatic polyamide, and vinyl chloride), natural fibers, and semi-synthetic fibers (cotton, rayon, wool, etc.). It can also be applied to those mainly containing aromatic polyamide fibers, such as knitted and woven fiber structures. Hereinafter, the present invention will be specifically explained with reference to Examples. Examples 1 to 6, Comparative Examples 1 to 3 Table 1 shows plain woven fabrics (30 count twin yarn spun yarn, basis weight 200 g/m ² ) made of polymetaphenylene isophthalamide fibers (Konex; manufactured by Teijin Ltd.). Mix urea and thiourea in the indicated weight ratio to obtain a concentration of 30
It was padded with an aqueous solution dissolved in water at a weight percent, squeezed with a mangle to a pick-up ratio of 80%, and then dried at a temperature of 100° C. for 4 minutes. Then, it was cured at 190°C for 1 minute. In Examples 1 to 6, PH is
6.5, 7.0 in Comparative Example 1, and 6.5 in Comparative Examples 2 and 3. The light resistance of the obtained treated fabric was measured and shown in Table 1.
It was shown to. As Comparative Examples 1 to 3, Table 1 shows 100% water (Comparative Example 1), urea alone (Comparative Example 2), and thiourea alone (Comparative Example 3). The light resistance was measured using a fade meter at 40
5 for no fading after irradiation (best)
The grades were divided into five grades, with extremely severe fading (worst) being grade 1. Experiments were conducted under the same conditions as in Example 3, except that the pH of the aqueous solution containing urea and thiourea was set to 5 or 9. When the PH adjuster is PH5, use acetic acid, and when the pH is 9
In this case, carbonated soda was used. The light resistance of the obtained treated fabrics was all 3.5 grade, which was good as in Example 3.

[Table] Example 7 and Comparative Example 4 (m/n=50/50) expressed in repeating units, fineness 1500 de/1000 f, strength 26 gr/d, elongation 4.5%, initial Young's modulus 600 g/d
Two aromatic poly(3,4'-diphenyl ether terephthalamide) copolymer fibers having physical properties were twisted together (15002) and S-twisted at 10T/10cm. The twisted yarn was putted in an aqueous solution containing 60 parts of urea and 40 parts of thiourea dissolved at a concentration of 30%, and squeezed with a mangle to a pick-up rate of 80%.
It was dried at 100°C for 4 minutes. Then, it was cured at 190°C for 1 minute. The pH was adjusted to 6.5 in Example 7 and 7.0 in Comparative Example 4. The light resistance of the obtained treated fabric was measured and shown in Table 2. In addition, as a comparative example, water
The case of 100% (Comparative Example 4) is also shown in Table 2.

[Table] Example 8 and Comparative Example 5 Du Pont KEVLAR-291500de was treated in the same manner as in Example 2, and the light resistance was measured. Table 3 shows the results. The pH was adjusted to 6.5 in Example 8 and 7.0 in Comparative Example 5. In addition, as a comparative example, 100% water
The case of (Comparative Example 5) is also shown in Table 3.

【table】

Claims (1)

[Claims] 1. A method for improving the light resistance of aromatic polyamide fibers, which comprises heat-treating aromatic polyamide fibers in the coexistence of urea and thiourea.