JPH03199412A - Ultrafine acrylic fiber - Google Patents

Abstract

PURPOSE:To provide the subject fiber composed of an acrylonitrile-based polymer having a high molecular weight, having single yarn fineness of >=a specified value, excellent in gloss, smoothness and lightweightness and capable of production of nonwoven fabrics and woven fabrics excellent in wiping properties and water retention and useful as a towel. CONSTITUTION:An objective fiber composed of an acrylonitrile-based polymer (preferably containing acrylonitrile in an amount of >=80wt.%) having >=200000 weight-average molecular weight and having <=0.05d single yarn fineness.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to ultrafine acrylic fibers having a single fiber fineness of 0.05 d or less.

[Conventional technology]

Acrylic fibers are known for their excellent physical properties, such as color development, brightness, fastness, light fastness, and corrosion resistance, and are widely used in clothing and interior applications. Usually, acrylic fibers are made by wet spinning, dry-wet spinning, or dry spinning, but in all of these spinning methods, the polymer is dissolved in a solvent [7] and the spinning stock solution is discharged from a spinning nozzle to impart it to the fiber. After molding,
It is characterized by requiring extremely complicated steps such as desolvation.

On the other hand, in general, when fibers are made thinner, they tend to wrap around spinning rollers, yarn guides, etc. and become fluffy during the spinning process. Alternatively, a method is used in which the sea-island-shaped fiber is made, and then the sea component is eluted, leaving only the island component.

Melt spinning of nylon, polyester, etc. is a simple process, so it is possible to obtain ultrafine fibers using this method.However, in the case of acrylic fibers, the spinning process is complicated, so it is difficult to obtain ultrafine fibers using composite spinning. However, it was difficult to produce ultrafine fibers.

Therefore, in order to manufacture ultra-fine acrylic fibers, it is necessary to reduce the fineness by reducing the diameter of the spinning nozzle and increasing the drawing ratio, which is an extension of the conventional manufacturing technology for acrylic fibers for clothing. However, even with this method, the limit is to obtain a single fiber fineness of about 0.1 d.

[Problem to be solved by the invention]

The purpose of the present invention is to obtain 0.05
The purpose of the present invention is to provide ultrafine acrylic fibers with a diameter of d or less.

[Means to solve the problem]

The present invention is directed to an ultrafine acrylic fiber having a single fiber fineness of 0.05 d or less and made of an acrylonitrile polymer having a weight average molecular weight of 200,000 or more.

The acrylonitrile (IJ) polymer used to produce the ultrafine acrylic fiber of the present invention has a weight average molecular weight of 2.
It must be 00,000 or more. In order to produce ultra-fine acrylic fibers, it is necessary to lower the acrylonitrile polymer concentration in the spinning dope and to increase the ratio of the linear velocity of the spinning dope from the spinning nozzle to the speed of the undrawn yarn, the so-called spinning draft, as much as possible. method is used.

Therefore, it is preferable to set the concentration of the acryloni)If-based polymer in the spinning dope to 10% by weight or less, but if the weight average molecular weight of the polymer used is less than 200,000,
Even if such a low-concentration spinning stock solution is prepared, it is impossible to continue spinning stably because its viscosity becomes low and spinnability is no longer expressed.

In addition, the acrylonitrile polymer used in the present invention contains 80% by weight of acrylonitrile in view of the physical properties of the fibers obtained.
It is necessary to contain the above amount. Examples of copolymerization components to be copolymerized with acrylonitrile include acrylic acid, methacrylic acid, methyl acrylate or methacrylate, ethyl acrylate or methacrylate, n-
Iso-1 or t-butyl acrylate or methacrylate, 2-ethylhexyl acrylate or methacrylate, α-chloroacrylonitrile, 2-hydroxyethyl acrylate or methacrylate, hydroxyalkyl acrylate or methacrylate, vinyl chloride, vinylidene chloride, bromide Examples include unsaturated monomers such as vinylidene, vinyl acetate, sodium salt of p-sulfophenyl methallyl ether, sodium methallyl sulfonate, etc.
Any monomer that copolymerizes with acrylonitrile may be used, and two or more types of monomers may be used in combination. The acrylonitrile polymer having a weight average molecular weight of 200,000 or more used in the present invention can be obtained by a suspension polymerization method.

Next, such an acrylonitrile polymer is dissolved in a solvent such as dimethylformamide, dimethylacetamide, dimethyl sulfoxide, rhodan salt aqueous solution, zinc chloride aqueous solution, or the like. Subsequently, the spinning stock solution is filtered through a material with an opening of 10 μm or less, and is discharged from a spinning nozzle. The diameter of the spinning nozzle is preferably small, and it is preferable to use a spinning nozzle with a diameter of 50 μm or less, preferably 40 μm or less. As the spinning method, wet spinning in which a spinning stock solution is discharged into a coagulation bath from a spinning nozzle is preferably used. The coagulation bath is generally a mixture of an acrylonitrile polymer solvent and water.

The coagulated thread thus obtained is subsequently drawn while washing and removing the remaining solvent. As for the stretching method, it is preferable to use a combination of flood stretching and hot rolls, hot plates, heating tubes, etc. in order to set a high stretching ratio and reduce the fineness.

In general, when the single fiber fineness is reduced, thread breakage in the coagulation bath and winding around spinning rollers, thread guides, etc. occur frequently.
However, surprisingly, the ultrafine acrylic fiber of the present invention has very good cohesiveness due to the large number of intertwining between single fibers, and therefore, it is possible to easily collect the spun yarn on the spinning roller or yarn guide. Since there is almost no single fiber breakage due to fiber splitting, processability is very good.

〔Effect of the invention〕

The single fiber fineness of the present invention that can be produced by the above method is 0.05.
Ultrafine acrylic fibers with a diameter of d or less have gloss, softness, and lightness that cannot be obtained with conventional acrylic fibers. In addition, the surface area per fiber weight is significantly increased compared to conventional acrylic fibers, so when non-woven fabrics and textiles are created, for example, the wiping performance is greatly improved, and the water retention rate is also greatly improved, so towels, washing machines, etc. It is also very effective as a fiber for commercial purposes.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to Examples.

Note that the weight average molecular weight (Mw) is a value calculated by the following formula by measuring the intrinsic viscosity of the polymer at 25° C. using dimethylformamide as a solvent.

[η] = 3.35 x 10-' [Mwl 0
72 EXAMPLES AND COMPARATIVE EXAMPLES An acrylonitrile polymer having a weight average molecular weight of 50,000 ttL and 30,000 ttL and acrylonitrile/vinyl acetate 92/8 (wt%) was obtained by suspension polymerization. Wet spinning was performed using each polymer under the following conditions.

Note that the numbers 1 to 4 above indicate comparative examples, and the numbers 5 to 8 indicate the present invention.

Next, the obtained fibers were opened to see how many times it would take to wipe off fingerprints left on a glass plate.

Number Single fiber fineness (d) Number of wiping (times) Number Single fiber fineness (d) Water retention rate (%) 03.0 (commercially available acrylic fiber) 13.25
0.05
42.58 0, 01
5(1,10,1 0,05 0,03 0,01 The smaller the single fiber fineness was, the better the wiping performance was.

Furthermore, the water retention rate was measured using the obtained fibers.

The water retention rate was measured using the following method.

The weight of the raw cotton obtained by immersing fibers refined in a conventional manner in water for 24 hours and dewatering them for 10 minutes under an acceleration of 1000 G is defined as W.

After drying this fiber with hot air at 110℃ for 3 hours, the weight is W
2 and calculated from the following formula.

Four two

Claims (1)

[Claims] Ultra-fine acrylic fiber with a single fiber fineness of 0.05d or less, made of an acrylonitrile polymer with a weight average molecular weight of 200,000 or more.