JP3491400B2 - Method for producing dyed aromatic polyamide fiber - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing dyed aromatic polyamide fibers (hereinafter sometimes abbreviated as aramid fibers).

[0002]

2. Description of the Related Art Aramid fibers are roughly classified into two types depending on the bonding position of an amide group in an aromatic ring. When the bonding position is in the meta position, meta-oriented aramid fiber (hereinafter, may be abbreviated as meta-aramid fiber), in the para position or in parallel with the para-position aramid fiber (hereinafter, para-aramid fiber and It may be abbreviated). All of the aramid fibers are characterized by excellent heat resistance and flame retardancy.

In particular, para-aramid fiber has excellent mechanical properties such as high strength and high elasticity, and is therefore used as a bulletproof check or the like, and because it has excellent cut resistance, it is also used as protective gloves or the like. In addition, meta-aramid fiber is used in heat-resistant protective clothing, etc., and is also used in high-temperature bag filters because it has excellent heat resistance especially for long periods.

Aramid fibers have the above-mentioned excellent properties, but have poor light resistance, and discoloration or reduction in strength occurs when exposed to sunlight, so they are used for applications exposed to sunlight. If it is not possible, even if it is used, special consideration such as coating with other material was required.

In order to improve this drawback, it is effective to dye the fiber to block sunlight, but the aramid fiber is chemically stable and thus has poor dyeability and is dyed in a dark color with good wash fastness. It was difficult. Therefore, heat-resistant protective clothing,
It is expensive because it is dyed by a special method when it is used in applications requiring various colors such as protective gloves and aircraft seat cover.

Various methods have conventionally been proposed for dyeing aramid fibers. For example, Japanese Patent Laid-Open No. 2-
Japanese Patent No. 41414 proposes a method of dyeing by directly adding a dye to a spinning dope. However, although this method allows the dye to enter the inside of the fiber and obtain a sufficient dyeing effect, the spinning equipment is contaminated with the dye, so it is not practical to arrange dyed yarns with many color tones in a small lot, which is not practical. .

Further, Japanese Patent Laid-Open No. 62-206088,
JP-A-62-206089, JP-A-62-223
Japanese Patent No. 384 proposes a method of modifying the surface of the fiber by metallizing or plasma-treating the fiber, and then dyeing the aramid fiber by a conventional method using a specific reactive dye. However, in these methods, usable dyes are limited, and the wash fastness of dyed yarn is not always sufficient.

Further, in Japanese Patent Laid-Open No. 63-152408, an aramid fiber having an intrinsic viscosity of 3.5 or more is swelled in water immediately after spinning and contacted with a dye solution in a state where the tension is relaxed. , A method of providing a dyed aramid fiber having high strength and high wash fastness and light fastness has been proposed.

Further, in the field of processing from fabrics such as heat-resistant protective clothing, it is often produced by blending with other fibers, and aramid fibers which can be dyed together with other fibers by conventional dyeing techniques are desired. Was there.

[0010]

SUMMARY OF THE INVENTION The present invention seeks to provide a process for producing dyed aromatic polyamide fibers having high wash fastness and light fastness using conventional dyeing techniques.

[0011]

[Means for Solving the Problems]

[1] Aromatic polyamide (A) and aromatic isocyanate or its blocked product (B) in a polar amide solvent or polar urea solvent as an A / B ratio (weight basis) of 60/40 to 99/1. A method for producing a dyed aromatic polyamide fiber, which comprises spinning an aromatic polyamide solution which is dissolved at a ratio of 1, and then dyeing the aromatic polyamide fiber obtained by heating. [2] The method for producing a dyed aromatic polyamide fiber according to the above item [1], wherein the aromatic polyamide is a para-oriented aromatic polyamide. [3] The method for producing a dyed aromatic polyamide fiber as described in [1] above, wherein the aromatic polyamide is a meta-oriented aromatic polyamide.

The present invention will be described in detail below. In the present invention, the para-aramid is obtained by polycondensation of a para-oriented aromatic diamine and a para-oriented aromatic dicarboxylic acid halide, and an amide bond has a para-position of an aromatic ring or an orientation position corresponding thereto (for example, 4, It is essentially composed of repeating units bonded in the opposite orientations such as 4′-biphenylene, 1,5-naphthalene, 2,6-naphthalene, etc., which extend in the opposite direction coaxially or parallel to each other. Phenylene terephthalamide), poly (parabenzamide), poly (4,4'-benzanilide terephthalamide), poly (paraphenylene-4,
4'-biphenylene dicarboxylic acid amide), poly (paraphenylene-2,6-naphthalene dicarboxylic acid amide), poly (paraphenylene / 3,4'-oxydiphenylene terephthalamide) or other para-oriented type or para-oriented type An aramid having a close structure is specifically exemplified.

Also included are those in which hydrogen of the benzene ring of the above-mentioned para-aramid is substituted with a halogen group, an alkyl group, a phenyl group or the like. Specific examples include poly (2-chloro-paraphenylene terephthalamide) and paraphenylene terephthalamide / 2,6-dichloroparaphenylene terephthalamide copolymers.

In the present invention, the meta-aramid means that the amide bond essentially consists of repeating units bonded at the meta position of the aromatic ring, and for example, 80 mol% or more of the repeating units of the molecular chain are metaphenylene isophthalamide. Is an aromatic polyamide and a copolymer thereof.

In the present invention, the mixing ratio of the aramid and the aromatic isocyanate or the blocked product thereof in the aromatic polyamide solution (hereinafter sometimes referred to as aramid dope) is such that the aramid is mixed with the aromatic isocyanate in an amount of 60 to 99 parts by weight. The blocked product is 1 to 40 parts by weight (100 parts by weight in total). When the amount of aramid is less than 60 parts by weight, the strength of the fiber produced from the dope is lowered. Further, when the amount of aramid exceeds 99 parts by weight, the dyeability is deteriorated. The aromatic isocyanate used in the present invention is represented by the following general formula.

[0016]

[Chemical 1] Here, n is 2 or more, and R is an aromatic group. In the method of the present invention, a blocked product of the aromatic isocyanate represented by the above formula may be used instead of the aromatic isocyanate. Further, dimers, trimers and blocked products of the aromatic isocyanates can be used.

In the present invention, a polar amide solvent or a polar urea solvent is used. Specific examples thereof include, but are not limited to, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, and tetramethylurea.

Meta-aramid and para-aramid can be dissolved in these solvents to obtain a stable dope as a raw material in the method of the present invention. Moreover, a stable aramid dope can be obtained by polymerizing para-aramid in these solvents. To this end, alkali metal or alkaline earth metal chlorides can be added to the solvent to improve the compatibility of the solvent with para-aramid. Para-aramid obtained by polymerizing a monomer having a substituent such as a phenyl group or a chlorine group tends to be a stable solution in the state of a polymerization solution. However, since these monomers are expensive, the amount used is restricted from the economical viewpoint. As a method for obtaining a stable para-aramid polymerization solution, there is a method for obtaining low-polymerization degree para-aramid in the above solvent. The method using an aramid dope obtained by polymerizing a low degree of polymerization para-aramid is an industrially advantageous method.

The low-polymerization degree para-aramid herein has an intrinsic viscosity (in the present invention, an intrinsic viscosity as defined later) of 1.0 to 2.5 dl / g, preferably 1.5.
Para-aramid having a value of ˜2.2 dl / g. If the intrinsic viscosity is less than 1.0 dl / g, sufficient mechanical strength as a para-aramid fiber cannot be obtained. Intrinsic viscosity is 2.5d
If it exceeds 1 / g, the polymerization solution will not be a stable liquid aramid dope, and a gel will be formed to make spinning difficult.

That is, in the method of the present invention, 4 to 10 para-aramid having an intrinsic viscosity of 1.0 to 2.5 dl / g is added to a polar amide solvent or polar urea solvent.
% Of alkali metal or alkaline earth metal chloride and 1 to 40 parts by weight of aromatic isocyanate or blocked product thereof against 60 to 99 parts by weight of para-aramid (para-aramid and aromatic isocyanate or its It is preferable to use a para-aramid dope comprising 100 parts by weight of the total of blocked products.

However, it is also possible to use as a comonomer in the case of a monomer or a copolymer having a high compatibility with the above-mentioned solvent within a range that can be economically used. In this case, it is assumed that the intrinsic viscosity of para-aramid or para-aramid copolymer is 2.5 dl / g or more,
The present invention does not exclude the case where a stable para-aramid dope can be produced.

After the aromatic isocyanate or its blocked product is added to the aramid dope, the following spinning step is performed. When a polymerization dope is used as the aramid dope, the aromatic isocyanate or its blocked product is added to the para-aramid dope after spinning after the polymerization. When an aromatic isocyanate or a blocked product thereof is added before or during the polymerization, a reaction with an aromatic diamine may occur, which may impair the stability of the dope. In order to prevent the reaction with an amine, a blocked product of aromatic isocyanate (hereinafter sometimes referred to as blocked isocyanate) is preferable.

A known method can be applied to the spinning. Specific examples thereof include wet spinning and dry wet spinning, for example, so-called air gap method. The fiber solidified after spinning is washed with water, and if necessary, further neutralized and then washed with water.

The aramid fiber is then dried by heating. The heating causes a reaction between the aramid fiber and the aromatic isocyanate or its blocked product.
After drying, hot stretching can be performed if necessary. Temperature control is important in the drying and optional hot stretching steps. Especially when a blocked isocyanate is used, it is necessary to heat at a temperature higher than the temperature at which the blocking agent used is desorbed.

In the present invention, the dyeing method is not necessarily limited, and a known method can be employed. For example, the aramid fiber obtained by the above method is immersed in an aqueous solution of various dyes for dyeing.

[0026]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The tests, evaluation methods and criteria in Examples and Comparative Examples are as follows.

1. Intrinsic viscosity measurement method The flow time was measured at 30 ° C. with a capillary viscometer for a solution in which 0.5 g of aramid was dissolved in 100 ml of 96-98% sulfuric acid and 96-98% sulfuric acid itself. Intrinsic viscosity was calculated from the calculated flow rate ratio by the following formula. Intrinsic viscosity = ln (T / T ₀ ) / C [unit: dl / g] where T and T ₀ are the flow times of the aramid sulfuric acid solution and sulfuric acid, respectively, and C is the concentration of the aramid solution (g / g).
dl) is represented.

2. Single Fiber Strength JIS L 1015 "Chemical Fiber Staple Test Method"
The measurement was carried out under the following conditions according to the method described in 1. (1) Fineness: Vibroscope method (2) Strength: Gauge length 10 mm, Crosshead speed 1
mm / min

3. Dyeability SICOM UC20 type spectrophotometer (Sumitomo Chemical Analysis Center Co., Ltd.)
Was used to measure the surface reflectance at a wavelength of 400 to 700 nm, and the color depth of the dyed yarn was measured.

4. Light resistance test A light resistance test was carried out under the following conditions in accordance with JIS L 0842 "Testing method for dyeing fastness to carbon arc lamp light". (1) Device: UV carbon arc FA-3 (manufactured by Suga Test Instruments Co., Ltd.) (2) Irradiation time: 20 hours (3) Black panel temperature: 63 ° C. (4) Discoloration of sample according to JIS L 0801 etc. The light fastness is determined by making a determination in accordance with the method of. Further, the strength of single fiber before and after the test is measured to determine the degree of fiber deterioration.

Example 1 [1] Polymerization of poly (paraphenylene terephthalamide) Poly (paraphenylene terephthalamide) was prepared using a 51 separable flask equipped with a stirring blade, thermometer, nitrogen inlet tube and powder addition port. Polymerization (hereinafter abbreviated as PPTA) was performed. The flask is thoroughly dried and N-methyl-2-
Calcium chloride 260., which was charged with 4200 g of pyrrolidone (hereinafter abbreviated as NMP) and dried at 200 ° C. for 2 hours.
0 g was added and the temperature was raised to 100 ° C. After calcium chloride was completely dissolved, the temperature was returned to room temperature, and 132.9 g of paraphenylenediamine (hereinafter abbreviated as PPD) was added and completely dissolved. While keeping this solution at 20 ° C. ± 2 ° C., terephthaloyl chloride (hereinafter abbreviated as TPC) 243.
3g was divided into 10 portions and added every 5 minutes. Thereafter, the solution was aged for 1 hour while maintaining the temperature at 20 ° C. ± 2 ° C., and stirred for 30 minutes under reduced pressure to remove bubbles. The obtained polymerization liquid (polymer dope) showed optical anisotropy. PT obtained by sampling a part and reprecipitating with water and taking out as a polymer
When the intrinsic viscosity of A was measured, it was 1.98 dl / g.

[2] Preparation of para-aramid-aromatic isocyanate addition dope Tolylene diisocyanate was added to the polymer dope of the above-mentioned [1] so as to be 5.6% by weight of the total amount of the polymer.
Stir for 30 minutes. A part of the polymer was sampled, reprecipitated with water and taken out as a polymer, and the intrinsic viscosity of the obtained polymer was measured and found to be 1.97 dl / g.

[3] Spinning of para-aramid-aromatic isocyanate-added dope The para-aramid dope of the above [2] was sufficiently degassed in a dope tank under reduced pressure to obtain a spinning dope. The dope is pushed out by a gear pump, the hole diameter is 50 μm and the number of holes is 5000.
It was spun into a 30% NMP aqueous solution from the nozzle. The spinning speed was 3 m / min. It was thoroughly washed with water and continuously dried to obtain para-aramid fiber. The para-aramid fiber obtained by drying at 300 ° C. immediately after washing with water has a tensile strength of 12.6 g / d.
Met.

[4] Dyeing of para-aramid fiber The dry weight of the para-aramid fiber of [3] above is 2
A g portion was sampled, dipped in a dyeing bath having the following composition, and then washed with a carpet dyeing machine (manufactured by Japan Dyening Machine) for 130
It was dyed at 1 ° C. for 1 hour. After taking out after cooling and washing with water 9
A para-aramid fiber dyed red was obtained by drying at 5 ° C. (1) Dye: Anionic disperse dye, Sumikaron Blue EF
BL 160mg (vs fiber, 8%) (2) pH adjuster (acetic acid / sodium acetate): 2.5ml
(PH 5.5) (3) Dispersant (Sumipon TF): 2.0 ml (4) Water: 250 ml The surface reflectance of the obtained blue-dyed para-aramid fiber was 23%, which was dyed dark blue. I found out that The light fastness was 4 to 5 grade.

Comparative Example 1 A para-aramid fiber was experimentally produced by the same method as in Example 1 except that the aromatic isocyanate in Example 1 was replaced with a fatty acid isocyanate. Specifically, Sumidule N3500 (trade name, manufactured by Sumitomo Bayer Urethane Co., Ltd., aliphatic polyisocyanate type) was used as the fatty acid isocyanate.
5% was added. The obtained para-aramid fiber was dyed in the same manner as in Example 1. The surface reflectance of the dyed para-aramid fiber was 7.6%, and the lightfastness was grade 3.

Comparative Example 2 In the same manner as in Example 1, commercially available para-aramid staple was dyed. The surface reflectance of the dyed para-aramid staple was 8.5%, and the light fastness was grade 2.

Comparative Example 3 Commercially available polymetaphenylene isophthalamide staple was dyed in the same manner as in Example 1. The surface reflectance of the dyed polymetaphenylene isophthalamide staple was 9.4%, and the light fastness was grade 3.

[0038]

EFFECTS OF THE INVENTION By dyeing an aromatic polyamide fiber using a conventional dyeing technique, a dyed aromatic polyamide fiber having high wash fastness and light fastness can be produced.

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) D01F 6/60 D01F 6/90 C08L 77/10

Claims (3)

(57) [Claims] 1. A polar amide-based solvent or a polar urea-based solvent containing an aromatic polyamide (A) and an aromatic isocyanate or a blocked product (B) thereof in an A / B ratio (weight basis) of 60/40 to 99. A process for producing a dyed aromatic polyamide fiber, which comprises spinning an aromatic polyamide solution dissolved in a ratio of / 1, and then dyeing the aromatic polyamide fiber obtained by heating. 2. The method for producing a dyed aromatic polyamide fiber according to claim 1, wherein the aromatic polyamide is a para-oriented aromatic polyamide. 3. The method for producing a dyed aromatic polyamide fiber according to claim 1, wherein the aromatic polyamide is a meta-oriented aromatic polyamide.