JPH03113012A - Acrylic filament - Google Patents

Abstract

PURPOSE:To obtain acrylic filaments having excellent dry feeling, handle of tension and rigidity and water absorption properties free from slimy feeling, continuously having numberless micro streaks on the surface of single yarn in the direction of fiber axis. CONSTITUTION:The objective filaments continuously having numberless micro streaks on the surface of single yarn in the direction of fiber axis. The filaments are obtained by subjecting polyacrylonitrile to wet spinning in nitric acid as a solvent and drawing the yarn under wet heat at 100-125 deg.C, preferably >=105 deg.C and at a drawing surplus ratio Y=Dc/Dr of 1.6-2.2 when Dc is draw ratio causing end breakage and Dr is draw ratio to stably produce the filaments.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an acrylic filament, and more specifically, it has a dry feel without the slimy feeling characteristic of synthetic fibers,
The present invention relates to an acrylic filament that has a firm texture and has improved water absorption performance.

[Conventional technology]

Synthetic fibers such as polyester, polyamide, and polyacrylonitrile are widely used in woven and knitted fabrics because they have many excellent properties.

However, woven and knitted fabrics made of these general-purpose synthetic fibers,
It does not have a dry or squeaky feel, and is significantly different from natural silk fabrics, especially natural hand-kneaded silk fabrics or linen milled fabrics, which have a firm, dry, supple texture.

In particular, polyacrylonitrile fibers have been able to achieve a softness and feel similar to that of wool among natural fibers due to advances in production and processing technology for these woven and knitted products.
The dry feel of silk fabrics and linen knitted fabrics is still insufficient.

The dry feeling mentioned here is unique to silk fabrics, especially hand-kneaded silk fabrics or linen woven and knitted fabrics, and is in contrast to the slimy feel of general-purpose synthetic fibers. Quantitative measurement is difficult, and it is generally determined by the touch of the fabric manufacturer.

[Problem to be solved by the invention]

The present inventors have solved the above-mentioned slimy feeling in woven and knitted fabrics made of polyacrylonitrile filaments, and have created a material that has a semi-kneaded silk feel and an excellent dry feel of traditional hemp woven fabric, and has a firm texture. In order to provide a woven or knitted fabric made of polyacrylonitrile filaments, we have made extensive studies to improve the raw material of polyacrylonitrile filaments, and have made the cross-sectional shape of the single fibers into a 1- or Y-shaped irregular shape and made the fineness of the single fibers larger. ,
Furthermore, the above objective has been met to some extent by producing these mixed fiber yarns of different fineness. However, in response to the demands of today's more sophisticated market, some problems such as roughness, unbalanced hardness, and a slimy feel remain, and the texture is still similar to that of polyester fabric. It was insufficient.

The purpose of the present invention is to eliminate the above-mentioned drawbacks, and to (1) have a dry feel without slimy feel, (2) have a chic and clean color tone and luster, and (3) have firmness and firmness. An object of the present invention is to provide an acrylic filament having a crisp taste.

[Means to solve the problem]

In order to achieve the above object, the present inventors have conducted extensive studies and found that in the conventional fiber manufacturing process, especially in the hot drawing process, by performing ultra-high humidity and heat high drawing in the extreme conditions below the stretchability margin, the molecular It was found that the orientation was performed specifically, and through the subsequent densification drying process, microscopic and clearly shaped striations became apparent, and the above objective was achieved.

The acrylic filament of the present invention is characterized by having numerous continuous microscopic scratches on the surface of the single fiber in the fiber axis direction.

The acrylic filament with striations of the present invention is produced by wet spinning polyacrylonitrile using nitric acid as a solvent and then stretching it to a predetermined ratio to produce a filament under conditions of heat, 100°C or higher and 125°C or lower. It can be obtained by carrying out stretching at a stretching margin Y of 1.6 to 2.2.

The drawing margin ratio Y here means that when setting the drawing ratio of acrylic filament under heat, if the drawing ratio is gradually increased under predetermined conditions, cut threads will occur when a certain drawing ratio value is reached. The draw ratio at which thread cutting occurs, which makes it impossible to manufacture yarn, is DC, and the draw ratio at which stable production is possible is Dr, and the ratio of the two is Y=Dc/Dr.
means.

In the present invention, if the stretching margin ratio is less than Y months, 6, there is no margin in the stretching conditions, and if there are fluctuations in the equipment or the prepared stock solution system, cut threads are likely to occur, making it impossible to achieve industrially stable production. On the other hand, if Y exceeds 2.2, the stretching ratio will be considerably low, the production rate will not be sufficiently increased, and this is economically disadvantageous. In addition, if the Y value exceeds 2.0, thermal adhesion, which can be called agglutination, occurs between single yarns during the drawing and drying process, which is not preferable.

In order to perform production at a low Y value, which is accompanied by disadvantages such as an increase in cut threads, it is preferable to homogenize the stock solution with high precision.

As a means of achieving this, we have implemented highly precise filtration to remove foreign substances that cause thread breakage, introduced grinders to further enhance the pure mixing effect of the stock solution for insidious dissolution of polymers, and A method of optimizing the roughness of the welding surface during the running and winding processes is adopted.

The stretching conditions to obtain microscopic and clear striations are as follows:
The temperature is preferably 100 to 125°C under heat, preferably 105°C or higher under pressure and heat. Even under steam or homolytic liquid at temperatures below 100"C, which have often been carried out at temperatures below 100"C, or under normal pressure conditions, streak-like marks may appear, but the extent of these marks is small and so slight that it is difficult to quantify them. Therefore, it does not form clear streaks like the one produced in the present invention,
Furthermore, knitted fabrics made from this yarn do not have the texture and high water absorption performance seen in the present invention.

By changing the shape of the spinneret during spinning from the conventionally standard perfect circular shape to shapes such as a single letter, a Y letter, and a cross, more clearly defined striations can be strongly produced.

The depth of the grooves of the striations on the surface of the single fiber varies depending on the manufacturing conditions, but if it is 0.01 to 0.3 μ, the depth of the grooves on the surface of the single fiber is 0.01 to 0.3μ, which is the objective of the present invention, and has a good texture and high water absorption. Acrylic filaments can be obtained.

Furthermore, the width of the groove in the circumferential direction of the single fiber, which corresponds to the area between the grooves, is generally 0.1 to 2μ, although the grooves are generated quite randomly and the number varies widely. be.

According to an electron micrograph, the surface of the filament of the present invention having striations having such groove depth and groove width has a shape resembling the skin of a cedar tree.

The acrylic fiber with micro striations of the present invention not only has excellent textures such as dryness, crispness, gentle touch, firmness and elasticity, and non-slimy feel, but surprisingly, the acrylic fiber with micro striations has Water absorption performance is significantly improved compared to those with no or only slight striations. The reason for this is not yet clear, but when the microscopic streaks come into contact with the water interface, the surface contact area of the fibers increases and an action similar to capillary color development 4 occurs, or the inside of the fibers It is thought that the structure itself is suitable for the passage of water molecules.

This water absorption performance is better than conventional acrylic filaments with no visible striations or with slight striations and a groove depth of 0.
For those with a diameter of less than 1 micron, the water absorption height according to the simplified bisic method described below is 40 mtn or less for a 150 denier, 60 filament yarn, whereas it is 50 mm or more for the same denier, same filament yarn of the present invention.

The acrylic filament having microscopic striations of the present invention can be twisted or false-twisted, or can be made into a knitted fabric as a raw yarn and commercialized.

〔Example] Hereinafter, the present invention will be explained in detail with reference to Examples.

The groove depth and groove width in the examples were measured by the following measurement method.

Figure 1 shows the cross-sectional shape of the surface layer of a single acrylic filament, magnified 20,000 times using an electron microscope.

In the figure, w,,w! and W3 are the widths between the peaks of the convex portions on the fiber surface layer, and D+, D2, and
, , wz , and w3 are the depths to the deepest part of the valley perpendicularly from the tangent line connecting the tops of the two mountains.

From the countless widths and depths corresponding to W and D in the surface layer of the fiber, select 10 widths and depths in the order of the largest D value from one circumference of one cross section, average these measured values, and calculate the length of the fiber. The depth D of the groove of the mark and the width W of the groove were defined.

W=[,,:E,wn]/n The texture of the knitted fabric was evaluated as follows.

A filament of 150 (f) was fed in the form of raw yarn to a 26 gauge knitting machine and knitted into a jersey texture. This knitted fabric was refined under boiling, and subjected to a grain finish to obtain a fabric for texture evaluation.

When evaluating the texture of the obtained fabric, since mechanical measurement is difficult, specialized engineers, knit designers, etc.10
Choose a name: (1) dryness, (2) crispness, (3)
The items of gentle touch, (4) firmness, waist, and (5) non-slimy feel were evaluated on a five-point scale, and the average value was used as the texture evaluation score.

In addition, water absorption performance was evaluated by the simple bisic method shown below.

After knitting acrylic fibers into a 22-gauge, 4-inch-diameter tubular knitted fabric into a jersey structure, a commercially available neutral detergent (0.5%
aqueous solution) at 60°C for 10 minutes.
After drying with hot air at 80°C, it was ironed with a dry heat at 80°C to remove wrinkles.

The lower 2 m of this knitted fabric was immersed in 250 cc of dye aqueous solution in a 500 cc beaker, and the water absorption height was measured after 10 minutes.

Example 1 The composition was acrylonitrile/methyl acrylate/sodium methallylsulfonate = 91.5/8.010.5 (% by weight), and the specific viscosity (polymer 0.58 was dissolved in 100 mj2 of dimethylformamide). (measured at 23°C),
An acrylonitrile copolymer having a molecular weight of 0.205 was dissolved in a 70% by weight concentrated nitric acid aqueous solution so that the polymer concentration was 14.5% by weight to prepare a spinning stock solution. In order to further homogenize the obtained stock solution, the mixture is repeated again using a grinder, and in order to remove as much as possible of undissolved foreign substances and semi-dissolved gel-like substances in the stock solution, a three-dimensional cut equivalent to a 10 micron cut is carried out. It was passed through a non-woven stainless steel type filter in two stages.

This spinning stock solution was discharged at a temperature of -3°C and had a diameter of 0.09 mm.
The undrawn yarn was spun through a nozzle with 60 round holes and discharged at a speed of 27 m/min into a 29 wt% dilute nitric acid solution maintained at 3°C. 13m/
It was taken over by a roller with a speed of 1 minute. After washing the undrawn yarn with water, it was first stretched 7.2 times in spring water at 100°C. The resulting drawing system was placed in a pressurized steam box with slit-like holes on both sides (1.5 kg/ctl
) and subjected to a second stretching of 2° and 5 times. The stretching margin ratio at this time was 1.15. The drawn yarn was then densified and dried under hot air at 200°C, and then wound at a speed of 130 m/min.

The obtained yarn was a 60 filament with a fineness of 150 denier and clearly visible microscopic striations. Table 1 shows the physical properties, hand evaluation scores, etc. of the knitted fabric using this yarn, and the knitted fabric was highly rated for its excellent dry feel.

Example 2 Spinning using a stock solution homogenized in the same manner as in Example 1,
Washing with water, stretching, and drying were performed. The spinning nozzle used at this time was single-shaped and had 15 holes each having a width of 0.05 mm and a length of 0.7 rm.

Stretching was performed using 8.5 times the primary stretching in a water-conducting bath and 1
．． The second stretching at 4 kg/cm was 2.35 times, and the total stretching was 20 times. At this time, the stretching margin is 1
．． It was 2.

Next, drying and winding were performed in the same manner as in Example 1.

The obtained yarn with a fineness of 150 denier and 15 filaments had a single-shaped cross-section, resembling the cross-section of a convex lens, and clearly had microscopic striations. Table 1 shows the results of the physical properties and texture evaluation scores of knitted fabrics using this yarn.
It had sufficient firmness and a good dry feeling.

Example 3 Composition is acrylonitrile/methyl acrylate/acrylamide/sodium methallylsulfonate = 90/415
．． An acrylonitrile copolymer with a specific viscosity of 0.213 at a weight ratio of 510.5% and a polymer concentration of 14.0
Dissolved in a 68% by weight concentrated nitric acid aqueous solution to give a concentration of 68% by weight,
It was used as a spinning stock solution. The obtained stock solution was subjected to removal of foreign substances and homogenization mixing in the same manner as in Example 1.

This spinning stock solution was discharged at -3°C, had a figure-7 flower shape, and a hole area of 0.015 mrrf per hole.
The slit width of the hole forming the letter shape is 0.05 [11111
Then, it was heated to -3°C through a nozzle with 30 holes.
20m/m in a 26% dilute nitric acid aqueous solution maintained at
Discharged at a speed of 1 minute.

Next, water washing, stretching, and drying were performed in the same manner as in Example 1. At this time, the stretching ratio was 9 times the first stretching in a hot water bath, 2 times the second stretching under steam pressure of 1.6 kg/ci・G, and a total stretching of 18 times. provided.

The obtained yarn having a figure 7 cross-sectional shape had extremely clear striations. Table 1 shows the results of the physical properties and hand evaluation scores of the knitted fabric using this yarn, and it was excellent in water absorption performance and dry feel due to microscopic striations. In addition, the bulkiness of the knitted fabric increased, and its texture was unique, and it received particularly high evaluation scores.

Comparative Example 1 The same acrylonitrile copolymer as in Example 1 was dissolved in a 70% by weight concentrated nitric acid aqueous solution so that the polymer concentration was 14.5% by weight to prepare a spinning stock solution. This spinning stock solution was discharged at -3°C and passed through a nozzle with 60 circular holes with a hole diameter of 0.10 mm into a 29% dilute nitric acid solution maintained at -3°C at a speed of 27 m/min. I spit it out.

The spun undrawn yarn was taken into a row row at a speed of 13 m/min. The obtained undrawn yarn was washed with water and then stretched 6 times (first stretching) in spring water at 100"C. Pass through the steam box (1,I) cg/ctA),
．． A second stretching of 2 times was performed. When the stretching margin ratio at this time was measured, it was 1.8. Next, this drawn yarn was
After densification and drying under hot air at °C, it was wound up at a speed of 130 m/min.

Obtained yarn (fineness 150 denier, 60 filaments)
The physical properties and appearance of the knitted fabric were investigated, and the results are shown in Table 1.

Comparative Example 2 A stock solution was prepared in the same manner as in Comparative Example 1, and the nonulle at the time of spinning was single-shaped, with a width of 0.04 + nm and a length of 0.4 mm.
- A thread having 30 holes was used, and the thread was washed with water in the same manner. The first stretching was done in spring water (1 to 5.5
The second stretching was carried out at a stretching ratio of 1.6 times under pressurized steam of 1.1 kg/afl.

The stretching margin ratio at this time was 1.9.

The obtained yarn had slight streaks, and Table 1 shows the evaluation of the physical properties and texture of the knitted fabric using the C yarn.

The following table shows the margins. [Effects of the Invention] The acrylic filament with microscopic streaks of the present invention provides a dry feel without the slimy feeling characteristic of synthetic fibers.
It is possible to obtain a woven or knitted fabric that has excellent texture such as firm waist and excellent water absorption performance.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the surface layer of an acrylic filament, magnified 20,000 times using an electron microscope.

Claims (1)

[Claims] (1) An acrylic filament with numerous continuous microscopic striations in the direction of the fiber axis on the single fiber surface.