JPH06101129A - Acrylic spun yarn - Google Patents

Abstract

PURPOSE:To obtain an ultrafine spun yarn having a vary small amount of nep, using acrylic yarn. CONSTITUTION:This acrylic spun yarn has the surface of acrylic fibers consisting of a particulate and/or microfibrillated structure having 0.10-0.5mum width and 0.05-10mum length and a fibrillated structure having 0.1-10mum width and 10mum or longer length, an aggregate of the particulate and/or microfibrillated structure and is modified cross-section yarn having 1.0-0.1 denier finess and 1.1-1.8 degree of modification.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spun yarn composed of ultrafine modified cross-section fibers. More specifically, it relates to an ultrafine spun yarn with a small number of neps.

[0002]

2. Description of the Related Art Acrylic fibers are widely used in the field of clothing such as knits and jerseys, the field of bedding such as blankets and the field of interiors by taking advantage of their excellent durability and vivid color development. Due to the diversification of needs, there is a high demand for spun yarn of fine count to extra fine count. However, in order to obtain spun yarns of these fine counts to ultra fine counts, it is necessary to use fine denier fibers of 1.0 denier or less, but a uniform yarn could not be obtained due to the generation of nep by the card.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an ultrafine spun yarn using acrylic fibers with a small number of neps.

[0004]

[Means for Solving the Problems] The present inventors have taken advantage of the excellent durability and vivid color development of acrylic fiber, and have recently met the needs of consumers for the demand for fine count to extra fine count spun yarn. As a result of earnest studies to respond to this problem, we have developed a uniform fine count to extra fine count spun yarn without nep by using atypical fine denier fiber.

That is, in a spun yarn made of an acrylic fiber composed of an acrylonitrile polymer or an acrylonitrile copolymer of the present invention, the surface of the fiber has a width of 0.0.
1 to 0.5 μm and a length of 0.05 to 10 μm, and a width of 0.1 to 10 μm, which is an aggregate of the particulate and / or microfibrillar structures, and the width of 0.1 to 0.5 μm.
A modified cross-section fiber having a fibrillar structure having a length of 10 μm and a length of 10 μm or more, and having a fineness of 1.0 denier to 0.1 denier and a degree of irregularity of 1.1 to 1.8. It is characterized by

The present invention will be described in detail below. The specific acrylic fiber used in the present invention and the method for producing the same are described in JP-A-61 / 1986.
-119707. That is, the acrylic fiber used in the present invention uses a dope prepared from an acrylonitrile polymer or an acrylonitrile copolymer and its solvent to form a fiber by a wet spinning method, and forms a skin layer of the dope. It can be obtained by a production method characterized by stretching in a stretching bath composed of a solvent and a coagulant set within the range of impossibility concentration.

The acrylic fiber used in the present invention is a fiber composed of an acrylonitrile polymer or an acrylonitrile copolymer, and the acrylonitrile copolymer contains 50% by weight or more of acrylonitrile. , Preferably 85% or more. As the copolymerizable monomer, acrylic acid and its esters, methacrylic acid and its esters, acrylamide and N-substituted amides, vinyl halides such as vinyl chloride, vinyl esters such as vinyl acetate, itaconic acid, Vinyl dicarboxylic acids such as maleic acid and its esters, vinylidene halides such as vinylidene chloride, vinyl pyridine and its N-substituted compounds, vinyl pyrrolidone, styrene, allyl sulfonic acid, methallyl sulfonic acid, sulfonic acid such as styrene sulfonic acid. Examples thereof include compounds and salts thereof, and two or more of them can be used for copolymerization.

The acrylic fiber used in the present invention has a fiber surface having a width of 0.01 to 0.5 μm and a length of 0.05 to 1
It is characterized in that it is composed of a particulate and / or microfibrillar structure arranged in a fiber direction of 0 μm.
In the conventional acrylic fiber, such a particulate and / or microfibrillar structure does not exist on the surface, and only lines relatively parallel to the fiber axis are observed.
The streaks found in conventional acrylic fibers are interpreted as wrinkles due to volumetric shrinkage of acrylic fibers generated in the stretching or heat treatment step, or in dry spun fibers, traces of solvent evaporation are interpreted as streaking due to stretching. It The particulate and / or microfibrillar structure of the acrylic fiber used in the present invention is unique to the present invention in which gel particles generated by microphase separation occurring during solidification are stretched in the fiber axial direction in the stretching step. It is a structural feature.
In the conventional acrylic fiber, coagulation is performed in a coagulation bath having a skin layer forming concentration lower than the skin layer incapable concentration range, so that a dense and hard skin layer is formed on the fiber surface during coagulation. Also, surprisingly, when the spinning method described below is adopted, the fiber is essentially transparent by coagulation and stretching, without any voids of about 100 to 2000 Å existing at the time of coagulation and stretching of conventional fibers. It turned out that The fiber suitable in the present invention is formed of a particulate and / or microfibrillar structure having a width of 0.05 to 0.3 μm and a length of 0.5 to 10 μm on the fiber surface, and the long axis of the structure. Are arranged in the fiber axis direction.

The existence of the particulate and / or microfibrillar structure is confirmed by a commercially available scanning electron microscope (for example, JSM-35CF manufactured by JEOL Ltd.) at an accelerating voltage of 5 to 15 kV and a magnification of 3000 to 30,000. It can be confirmed under double observation conditions.

Further, the acrylic fiber used in the present invention is
The surface has a width of 0.1 to 10 μm and a length of 50 formed by the aggregate of the particulate and / or microfibrillar structures.
One of the features of the structure is that it is composed of a fibrillar structure having a size of μm or more. The long axis of the fibrillar structure is arranged almost parallel to the fiber axis direction. A preferable one is characterized in that a fibrillar structure having a width of 0.1 to 10 μm is continuous in the fiber axis direction for a length of 10 μm or more. In the conventional acrylic fiber, the presence of such fibrillar structure cannot be confirmed, but it is similar to the fibrillar structure of the present invention which is considered to be formed by the wrinkles due to the volume contraction or the trace of evaporation of the solvent. It is characterized by the presence of muscles. However, the continuity of the muscle in the fiber direction is generally 50 μm or less, and usually 1 to
Mostly about 30 μm. The presence of this fibrillar structure can also be confirmed by the above-mentioned scanning electron microscope.

The acrylic fiber used in the present invention is a coagulation bath containing a dope prepared from an acrylonitrile polymer or acrylonitrile copolymer and its solvent in a concentration range in which the skin layer cannot be formed and a toughening agent. Then, it is obtained by drawing in a drawing bath composed of a solvent and a coagulant, which are set to a concentration not more than the coagulable concentration in the concentration range where the skin layer cannot be formed.

Here, the concentration range in which the skin layer cannot be formed can be determined by a scanning electron microscope. Apply the dope used for fiber formation to several μm to 1 μm on a slide glass.
It is applied to a thickness of about m and immersed in a coagulation bath prepared from a solvent and a coagulant. The temperature of the coagulation bath is set to the temperature used for fiber formation. The coagulation bath is prepared by changing the concentration so that the weight% of the solvent in the coagulation bath is in 1% intervals. After the completion of coagulation, the film is washed with water, washed with methanol and then air-dried to obtain a film-like product. Using an electron microscope, the surface of this film is subjected to an acceleration voltage of 5 to 15
Observe at kV and 1000 times magnification. When observing, 50
Coat the surface with ~ 500Å thick Au. By this observation, when a skin layer is formed, 100
At a magnification of 00 times, the surface of the film is smooth and only some undulations and deposits are observed. When the skin layer is in the concentration range in which it cannot be formed, pores of 0.05 to several tens of μm and particles of about 0.05 to 0.5 μm are observed on the surface. By this method, the lower limit concentration of the concentration range in which the skin layer cannot be formed can be determined.

The coagulation bath used in the wet spinning method of acrylic fibers used in the present invention comprises a solvent capable of dissolving an acrylonitrile polymer or an acrylonitrile copolymer and a coagulating agent. As the solvent, a concentrated aqueous solution of an inorganic salt such as rhodan salt, lithium bromide, zinc chloride, or aluminum perchlorate as an inorganic solvent, or an amide compound such as dimethylformamide or dimethylacetamide as an organic solvent, a nitrile compound, dimethyl. Sulfones such as sulfoxide and sulfoxide compounds, thiocyanate compounds, nitro compounds, amino compounds, phosphorus compounds, carbonate compounds and mixtures thereof are used. Further, as the coagulant, water, methanol, ethanol, acetone, acetic acid, ethylene glycol, carbon tetrachloride, xylene, benzene or the like is used. As the composition of the coagulation bath industrially used, a combination of the above-mentioned solvent and water is generally used, and from the viewpoint of productivity such as recovery, the solvent in the coagulation bath and the solvent in the dope are usually the same. Used.

Usually, the concentration of the solvent in these coagulation baths is in the concentration range in which the skin layer is formed. This is because, in consideration of industrial productivity, conditions that are excellent in spinning stability and operability are selected.
Further, in the concentration range where the skin layer cannot be formed, there were problems that the fibers coagulated in the coagulation bath meander, the resulting fibers become cloudy, the transparency is lost, and coagulation takes a long time. . The concentration range in which the skin layer cannot be formed varies depending on the type of solvent of the acrylonitrile polymer or acrylonitrile copolymer used in the coagulation bath, but when the coagulant is water, it is 38 to 50 wt% in nitric acid, dimethylformamide, dimethylacetamide. 65 to 90% by weight for dimethyl sulfoxide, and 20 for rhodanate and zinc chloride
A range of ˜40% by weight is preferably used, but since the proper concentration will change somewhat depending on the temperature and addition of the third component, an accurate determination should be made by using the above-mentioned scanning electron microscope. is there.

The acrylic fiber used in the present invention is wound up from the coagulation bath and then drawn in a drawing bath set to a concentration range in which the skin layer cannot be formed. Usually, the draw ratio is set within the range of 2 to 20 times. Preferably, 5 times or more is used. Stretching may be carried out at room temperature, but the temperature may be raised in some cases to enhance the stretchability. In addition, multistage drawing may be performed. By this drawing, void-free, well-aligned microfibrils and fibrils are formed in the acrylic fiber used in the present invention. When stretching is not suitable, voids are generated in the fiber, the microfibrils and fibrils are incompletely arranged, and the physical properties are deteriorated. The acrylic fiber used in the present invention is subjected to usual water washing treatment to remove the amount of residual solvent to less than 0.1% based on the weight of the fiber. Further, in order to increase physical properties such as strength, it may be re-stretched in hot water or steam. To remove more water, dry under tension or under tension. Then, heat treatment is performed to increase stability. As the method of heat treatment, a heated atmosphere such as pressurized steam, hot air, hot water, or on a hot plate is used.

The fineness (denier) of the acrylic fiber used in the present invention is a fine denier of 1.0 denier or less, and the degree of modification of the fiber is 1.1 to 1.8, preferably 0.4 to 0. 2.8 denier and 1.2 to 1.6 are preferable. The types of variants include eyebrow type, triangular type, polygon type, and 3 type.
A leaf type, a Y type, a U type, a cross type and the like can be used. The degree of atypicalness (V) referred to here is defined by the following. A value (r / d = V) obtained by dividing the diameter (r) of the circumscribed circle of the fiber cross section (magnified 500 times) by the denier (d).
A value obtained by dividing the calculated diameter (r0) by assuming a perfect circle in the same denier as 1) by the denier (d) (r0 /
d = V0), expressed as V1 / V0 = V. In order to obtain a more uniform spun yarn, the fiber length is 28 mm to 50 mm, preferably 32 mm to 38 mm, and any of 2 inch, cotton spinning ring spinning and open end spinning can be obtained.

The acrylic fiber used in the present invention is 1
The spun yarn may be composed of 00%, but at least 30 wt
%, The effect of the present invention is exhibited even if natural fibers such as cotton, silk and wool, and other synthetic fibers having a denier of 1.0 or less are mixed.

[0018]

EXAMPLES The present invention will be described in detail below based on examples. In the present invention, + 200% nep was measured by using an Ibnesta tester manufactured by Keisokuki Kogyo Co., Ltd. to obtain the number of nep of the yarn.

Examples 1 to 3, Comparative Example 1 Acrylonitrile 91.5%, methyl acrylate 8%,
A copolymer of 0.5% sodium methallyl sulfonate was added at 0 ° C,
It was dissolved in a 67% nitric acid aqueous solution to prepare a 16% spinning stock solution. Next, add this stock solution to a hole area of 0.01 mm ² and 100 holes.
Y type spinneret with 0, hole area 0.008 mm ² , hole number 1000
Extruded into the coagulation bath using a regular elliptical spinner. At this time, the coagulation bath was a 42% aqueous nitric acid solution and the temperature was 5 ° C. Subsequently, the film was drawn 10 times in a drawing bath having a nitric acid concentration of 42% and a bath temperature of 70 ° C. The fiber that has been stretched is washed with water 13
It was sufficiently dried in hot air of 0 ° C. and subjected to heat relaxation treatment with steam of 120 ° C. to obtain fibers having a single yarn fineness of 0.8 denier and 0.4 denier. As a result of observing the obtained fiber with a scanning electron microscope, it is found that microfibrillar structures having a width of 0.01 to 0.5 μm and a length of 0.5 to 3 μm are arranged in the fiber axial direction on the surface of the fiber. Was recognized. Further, the microfibril-like structures are aggregated to have a width of 0.5 to 5 μm, a length in the fiber axis direction of at least 10 μm, and a long one is 35
It was observed that a fibrillar structure having a size of 0 μm or more was formed.

Thus obtained 0.8 denier and 0.4 denier acrylic fibers of the present invention and, as a comparative example, 0.9 denier of common acrylic fibers (trade name: Casimiron manufactured by Asahi Kasei Kogyo) Spinning was performed using a spinning type spinning device. In Examples -1 to 3, regular elliptical fibers having a variation degree of 1.3 and 0.4 denier and 0.4 denier with a variation degree of 1.8 and 0.8 denier were used as 38 mm short fibers in a normal cotton spinning process. Was used for blended cotton-curd-drawing-rough spinning-spinning. With the acrylic fiber of Comparative Example and fine denier less than 1.0 denier, carding on a card machine is difficult, and sliver with a lot of nep can be obtained because it wraps around the needle cloth / wire or sinks. It has no value. However, in Examples 1 to 3,
At a spinning speed of 60 m / min with a gel of 0 g / m, the card could be passed through and a sliver without nep was obtained. These slivers are bulkier than the conventional fine denier, the pulling force of the sliver is very low, the drawability of the drawing and roving is stable, there is little unevenness, and napless roving can be obtained. Table 1 shows the results of the evaluation of nep using these rovings as yarns of 120 m count (twist number = 1100 T / m) with a ring spinning machine.

[0021]

[Table 1]

As shown in Table 1, the spun yarns of Examples 1 to 3 had a very small number of neps, and the value was the same as the number of neps of 52-meter-count yarn spun using 1.5 to 2.0 denier. At the same level. On the other hand, the nep of the spun yarn of Comparative Example 1 is very high.

[0023]

EFFECTS OF THE INVENTION By using an acrylic fiber having an extra fine irregular cross section, it is possible to obtain a uniform extra fine count yarn without nep by cotton spinning.

Claims (1)

[Claims] 1. A spun yarn made of an acrylic fiber composed of an acrylonitrile polymer or an acrylonitrile copolymer, wherein the surface of the acrylic fiber has a width of 0.0.
1 to 0.5 μm and a length of 0.05 to 10 μm, and a width of 0.1 to 10 μm, which is an aggregate of the particulate and / or microfibrillar structures, and the width of 0.1 to 0.5 μm.
A modified cross-section fiber having a fibrillar structure having a length of 10 μm and a length of 10 μm or more, and having a fineness of 1.0 denier to 0.1 denier and a degree of irregularity of 1.1 to 1.8. Acrylic spun yarn characterized by that.