JPH05279913A - Acrylic fiber and its production - Google Patents

Abstract

PURPOSE:To provide the acrylic fibers reduced in the generation of and in the change of the color by high temperature treatments. CONSTITUTION:The acrylic fiber comprises an acrylonitrile polymer comprising at least 95wt.% of acrylonitrile, having sulfonate groups in an amount of >=1X10<-4>mol/g and having an intrinsic viscosity of 1.0-3.0, and has the maximum shrinkage rate of <=1% when heated to 120 deg.C in the relation between the temperature measured under the heating condition and the dimensional change of the fiber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acrylic fiber having excellent dimensional stability at high temperatures and a method for producing the same.

[0002]

2. Description of the Related Art Acrylic fibers have excellent properties not found in other general-purpose clothing fibers such as nylon and polyester fibers, such as dyeing sharpness and bulkiness.
It is manufactured in large quantities for clothing, interiors such as carpets and curtains. However, at the same time, it has the disadvantages of sagging due to high temperature treatment and great discoloration and discoloration, so it cannot be used for textiles in the field of clothing and electric carpets in the field of interior, and it is hardly used for industrial materials. I could not use it.

Therefore, various proposals have been made to improve the characteristics of the acrylic fiber. For example,
Japanese Patent Application Laid-Open No. 51-73587 discloses itaconic acid, butenetricarboxylic acid and the following formulas.

[0004]

[Chemical 1] There is disclosed an acrylonitrile fiber or film having a crosslinked structure, which is obtained by copolymerizing the compound represented by the formula (3) with acrylonitrile at a ratio of 0.3 to 3 mol%.

Japanese Unexamined Patent Publication (Kokai) No. 53-126322 discloses a 1,6-diene compound containing acrylonitrile as a main component and containing oxygen, sulfur, or nitrogen atoms, for example, diallyl ether. The publication discloses fibers of an acrylonitrile polymer having a cyclic structure obtained by copolymerizing a divinyl compound, for example, divinyl ether, in place of the 1,6-diene compound.

All of these known techniques are intended to improve the properties of acrylic fibers by introducing a cross-linking structure or a ring structure into the fibers. However, the methods of these known techniques complicate the manufacturing process, and further, by introducing a cross-linking structure or a ring structure into the fiber, the properties originally possessed by the acrylic fiber may be changed, so that it is versatile. It is hard to say that this is the best method.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an acrylic fiber which is less liable to discoloration or discoloration due to high temperature treatment, and a technique for easily producing such an acrylic fiber industrially. To provide.

[0008]

The gist of the present invention is that it is composed of at least 95% by weight of acrylonitrile and has 1 × 10 ⁻⁴ mol / g or more sulfonic acid groups.
A fiber made of an acrylonitrile-based polymer having an intrinsic viscosity of 1.4 to 3.0, and in the relationship between the temperature and the dimensional change measured at elevated temperature, the maximum shrinkage rate when heated to 120 ° C. A gel obtained by discharging an acrylic fiber having good dimensional stability, characterized by being 1% or less, and a spinning dope obtained from the acrylonitrile polymer specified here from a spinning nozzle and introducing it into a coagulation bath. The present invention is a method for producing an acrylic fiber having good dimensional stability, which comprises stretching a coagulated coagulated yarn 4 to 8 times and then subjecting it to wet heat treatment at a temperature of 90 to 150 ° C. to shrink it by 5 to 50%.

The acrylonitrile polymer used in the present invention is prepared from at least 95% by weight of acrylonitrile and a monomer copolymerizable with acrylonitrile. Examples of the monomer that is copolymerized with acrylonitrile include acrylic acid, methacrylic acid, lower alkyl esters of itaconic acid, vinyl acetate, methacrylamide, acrylamide, vinyl chloride, vinylidene chloride, and the like. One or two
More than one species can be copolymerized.

Further, the acrylonitrile polymer used in the present invention must contain at least 1 × 10 ⁻⁴ mol / g of sulfonic acid group because of the dyeability of the obtained fiber, A method of copolymerizing a vinyl monomer having a sulfonic acid group such as 2-acrylamido-2-methylpropanesulfonic acid, allylsulfonic acid, P-styrenesulfonic acid, and methallylsulfonic acid is used for the introduction. As the method for polymerizing the acrylonitrile-based polymer, any known method such as water-based polymerization, emulsion polymerization and solution polymerization can be adopted.

Further, the acrylonitrile-based polymer having a molecular weight of 1.0 to 3.0 expressed by intrinsic viscosity is used. If the intrinsic viscosity is less than 1.0, the drawability during spinning will be reduced, and it will be difficult for the fiber to retain sufficient mechanical strength. On the other hand, when the intrinsic viscosity exceeds 3.0, it is necessary to set the concentration of the stock solution to be low in order to ensure spinnability. In that case, the mechanical strength of the fiber is lowered, or the fiber is easily fibrillated.

Next, the acrylonitrile polymer is dissolved in an organic solvent such as dimethyl sulfoxide, dimethylformamide, dimethylacetamide, an inorganic solvent such as rhodanesoda, or a mixed solvent thereof, and the obtained polymer solution is used as a spinning stock solution. use. The diameter of this spinning solution is 30
A gel-like coagulated yarn is obtained by discharging from a spinning nozzle of ˜300 μm into a coagulation bath. The obtained coagulated yarn is drawn in a range of 4 to 8 times. If the draw ratio is less than 4 times, the tensile strength of the fiber is insufficient, while if it exceeds 8 times, single yarn breakage easily occurs.
Further, it becomes easy to fibrillate. Stretching is preferably performed in warm water.

Subsequently, the stretching system obtained in the above steps is heated in a moist heat atmosphere at a temperature of 90 to 150 ° C. for 5 to
Shrink in the range of 50%. If the shrinkage is less than 5%, the tensile elongation of the fiber will be insufficient, and if it exceeds 50%, the tensile strength of the fiber will be insufficient. The wet heat atmosphere for shrinking is preferably hot water or steam. The shrinking step is performed before or after the step of applying the oil agent to the fiber, or after the drying step.
It can be carried out once or several times.

The acrylic fiber of the present invention obtained by the above method has a tensile strength of 2 to 5 g / d, that is, not so high strength, and has a suitable tensile strength as a so-called clothing fiber. If the tensile strength is less than 2 g / d, the fibers are likely to be cut in a normal spinning process, and if it exceeds 5 g / d, the strength becomes high and the tensile strength becomes insufficient, and the elongation as a spun yarn becomes insufficient.

Further, since the acrylic fiber of the present invention contains 95% by weight or more of acrylonitrile, it is excellent in dimensional stability in a high temperature range as compared with conventional acrylic fibers for clothing. That is, the maximum shrinkage ratio when the temperature was raised to 120 ° C. was 1% or less in the relationship between the temperature and the dimensional change measured under elevated temperature, and the acrylic fiber of the present invention was 1% or less.
The dimensional stability when heated to 20 ° C. or higher is significantly improved as compared with conventional acrylic fibers for clothing. Furthermore, the acrylic fiber of the present invention has an elongation of 25 to 60% and good spinnability.

[0016]

The present invention will be described in more detail with reference to the following examples. The intrinsic viscosity and the strongly acidic group content of the polymer were calculated by the following measurements and calculations. 1. Intrinsic Viscosity Measured at 25 ° C. using dimethylformamide as a solvent.

2. Strongly acidic group content About 1 g of polymer was precisely weighed, dissolved in dimethylformamide, then mixed and stirred with strong acid type cation exchange resin (50 to 100 mesh 3 g) for 1 hour, and then the resin was filtered off using a glass filter. To do. Furthermore, the above filtrate was titrated with a potentiometric titrator using KOH of 1/100 N (normal). In addition, a blank test was performed under the same conditions to make a correction.

[0018]

[Equation 1]

A: Polymer weight B: 1 / 100N NaOH sample titer (ml) C: 1 / 100N NaOH blank test titer (ml) f: 1 / 100N KOH titer 3. The copolymer composition ratio of the polymer is JEOL GSX-400.
The hydrogen nuclear magnetic resonance spectrum was measured using a superconducting FT-NMR apparatus, and calculated from the area ratio of the absorption peaks.

4. The relationship between the atmospheric temperature and the dimensional change was determined by applying a load to the sample at a rate of 5 mg / d, raising the temperature at a rate of 5 ° C./min in a constant temperature bath, and measuring the dimensional change at that time. 5. The measurement of the single fiber strength and elongation was in accordance with JIS-L1015.

Examples and Comparative Examples Acrylonitrile polymers shown in Table 1 were obtained by the suspension polymerization method.

[0022]

[Table 1]

Subsequently, a polymer solution having a concentration of 22.0% in which each of the acrylonitrile-based polymers a to d shown in Table 1 was dissolved in dimethylacetamide was supplied from a nozzle having a diameter of 80 μm to dimethylacetamide / water = 40/60. (Wt%), 3
It was discharged into a coagulation bath at 0 ° C. to obtain a coagulated yarn. Then, as shown in Table 2, fibers were obtained by changing the drawing and heat treatment conditions. The physical properties are shown in Table 2. No. 2 listed as a comparative example in Table 2. The fiber of No. 2 has a large elongation (the dimensional stability becomes poor) when the temperature is raised to a high temperature region exceeding 120 ° C.
Become. The dyeability was also poor.

[0024]

[Table 2]

No. 2 in Table 2 1 (curve 1), No. 2 (curve 2), No. The state of dimensional change when heat is applied to the fiber obtained in No. 4 (curve 4) is shown in FIG.

[0026]

INDUSTRIAL APPLICABILITY The novel acrylic fiber of the present invention is superior in dimensional stability in a high temperature range as compared with the conventional acrylic fiber for clothing, and has an improved balance of strength and elongation. There is. As a result, it has become possible to use it in fields that could not be used with ordinary acrylic fibers such as textile applications and electric carpets.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the temperature of acrylic fibers and the shrinkage ratio (%).

[Explanation of Codes] 1 Comparative Example Fiber 2 Comparative Example Fiber 4 Fiber of the Present Invention

[Chemical 2]

Claims (2)

[Claims] 1. A fiber composed of at least 95% by weight of acrylonitrile, having a sulfonic acid group of 1 × 10 ⁻⁴ mol / g or more, and an acrylonitrile polymer having an intrinsic viscosity of 1.0 to 3.0. An acrylic fiber having good dimensional stability, which is characterized by having a maximum shrinkage ratio of 1% or less when heated to 120 ° C. in the relationship between temperature and dimensional change measured under elevated temperature. 2. A spinning stock solution obtained from the acrylonitrile-based polymer specified in claim 1 is discharged from a spinning nozzle and introduced into a coagulation bath to obtain 4-8 gel-like coagulated fibers.
A method for producing an acrylic fiber having good dimensional stability, which comprises subjecting the sheet to double stretching and then subjecting it to wet heat treatment at a temperature of 90 to 150 ° C. to shrink it by 5 to 50%.