JPH0116948B2 - - 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 heat resistance such as strength retention at high temperatures, morphological stability, and thermal decomposition, flame resistance, and flame retardancy. It not only has excellent properties, but also has highly desirable physical and chemical properties such as chemical resistance, electrical properties, and mechanical properties such as strength and Young's modulus. Suitable for applications such as high strength, high Young's modulus fibers, and film molding materials. For example, it can be used as an electrical insulating material for motors, transformers, etc., and 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 edge-resistant safety clothing in aviation uniforms, firefighting work uniforms, etc. Furthermore, by blending, knitting and weaving rayon, cotton wool, etc.
By adding functions such as sweat absorption, moisture absorption, and heat retention to the high functionality 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. Purpose of the Invention The purpose 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. I haven't been able to 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 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 containing an ultraviolet absorber in the coexistence of urea and thiourea." In the present invention, compounds represented by the following general formula can be used as the ultraviolet absorber. (1) Phenylbenzotriazole or (2) 2,2'dihydroxybenzophene (Here, both X and Y represent hydrogen, halogen, alkyl group, or alkoxyl group, and X and Y may be the same or different. n is 1
Indicates an integer of ~4. ) These compounds not only have an affinity for aromatic polyamide-based polymers and have good blendability, but also have a high absorption ability for light with a wavelength of 340 to 410 mμ, such as The following can be mentioned. 2-(2'-hydroxy-5'-methylphenyl)
Benzotriazole, 2-(2'-hydroxy-
3′-chloro-5′-methylphenyl)benzotriazole, 2-(2′-hydroxy-3′-chloro-5′-
t-butylphenyl)benzotriazole, 2,
2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,
Examples include 4'dibenzyloxybenzophenone. Among these, 2-(2'-hydroxy-
Particularly preferred are 5'-methylphenyl)benzotriazole and 2,2'-dihydroxy-4,4'-dimethoxybenzophenone. As a method for incorporating the ultraviolet absorber into the aromatic polyamide fiber, it may be added during the polymerization process of the aromatic polyamide, or it may be added to the aromatic polymer solution (polymer dope). The amount of the ultraviolet absorber added is 1 to 15% by weight, particularly preferably 3 to 12% by weight, based on the aromatic polyamide. If the amount of the ultraviolet absorber is less than 1% by weight, little effect of improving light resistance will be observed, and if it exceeds 15% by weight, the flame retardancy will decrease. 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 ₁ , 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 a 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
-,

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-pyridylene 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, n-propyl group),
It may be included as a substituent for lower alkoxy groups (methoxy, ethoxy groups), cyano groups, acetyl groups, nitro groups, and the like. Hereinafter, a method for applying a mixture of urea and thiourea to an aromatic polyamide fiber containing an ultraviolet absorber will be described in detail. The present invention has a significant effect on improving light resistance only when urea and thiourea coexist, and no significant effect is observed when treated with urea or thiourea alone. For example, when applying a mixture of urea and thiourea to an aromatic polyamide fabric containing an ultraviolet absorber, it is effective whether it is applied in the form of powder or solution; After patting, it is wrung out with a mangle or 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. 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 preferably 180-190℃, 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 copolymer with an aromatic polyamide having a functional group having an affinity for dyes in the polymer chain. In this way, with the third component,
The effects of the present invention are particularly great when aromatic polyamides with improved dyeability are used. This seems to be because the deactivation reaction of amino groups is effectively carried out 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 using aromatic polyamide fibers alone, but also blends and cross-spun them with other synthetic fibers (fibers made of polyester, aliphatic polyamide, vinyl chloride, etc.), natural fibers, and semi-synthetic fibers (cotton, rayon, wool, etc.). It can also be applied to materials that partially contain fibrous structures formed by knitting and weaving, but mainly contain aromatic polyamide fibers. Effects of the invention By heat-treating aromatic polyamide fibers containing an ultraviolet absorber in the coexistence of urea and thiourea, the light resistance is significantly improved compared to the case where no ultraviolet absorber is contained, and at the same time, the strength due to light irradiation is improved. Deterioration is reduced (strength retention rate is improved). Examples Hereinafter, the present invention will be specifically explained using examples. Example 1, Comparative Examples 1 and 2 Tinuvin 326 (ultraviolet absorber, Ciba Geigy Co., Ltd.) for polymetaphenylene isophthalamide
Concentration of urea and thiourea mixed at a weight ratio of 60:40 and dissolved in water with 40-count double-thread polymethaphenylene isophthalamide short fibers (Konex, manufactured by Teijin Ltd.) containing 5 weight of product). It was packed in a 30% by weight aqueous solution and reduced to a pick-up rate of 80% using a mangle. Then, after drying at a temperature of 100°C for 4 minutes, curing was performed at 180°C for 1 minute. The light resistance of the obtained treated yarn was measured.
It was grade 4.5. In addition, when a similar test was conducted using polymetaphenylene isophthalamide short fibers that did not contain Tinuvin 326, the result was grade 3.5. (Comparative Example 1) Light resistance is determined using a fade meter, with no fading after 40 hours of irradiation (best) being grade 5, and severe fading (worst) being grade 1. It was classified and judged. The strength and elongation before and after the light resistance measurement (before and after 40 hours of light irradiation) was measured using a Tensilon. As a comparative example, the strength and elongation were measured when padding was performed using water instead of a mixed aqueous solution of urea and thiourea, and the results are shown in Table 1.

[Table] Examples 2 to 7, Comparative Examples 3 to 5 Plain woven fabric (30
Spun yarn with a count of double yarn, fabric weight 200 g/m ² ) was mixed with urea and thiourea at the weight ratio shown in Table 2.
It was padded with a 30% by weight solution dissolved in water, 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. The light resistance of the obtained treated fabric was measured and shown in Table 2. As Comparative Examples 3 to 5, Table 2 shows 100% water (Comparative Example 3), urea alone (Comparative Example 4), and thiourea alone (Comparative Example 5).

【table】

[Table] Example 8 and Comparative Example 6 Expressed in repeat units, fineness 1500de/1000fil,
Strength 26gr/de, elongation 4.5%, initial Young's modulus 600gr/
Two aromatic poly(3,4'-diphenyl ether terephthalamide) copolymer fibers containing 5% by weight of Tinuvin 326 and having the physical properties of S-twisted. The combined twisted yarn was padded in an aqueous solution with a concentration of 30% in which a mixture of 60 parts of urea and 40 parts of thiourea was dissolved in water, 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 light resistance of the obtained treated fabric was measured and shown in Table 3. In addition, as a comparative example, 100% water
The case of (Comparative Example 6) 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 containing an ultraviolet absorber in the coexistence of urea and thiourea.