JPH0441728A - Tow system spun yarn - Google Patents

Abstract

PURPOSE:To obtain a tow system spun yarn, constructed from an acrylic (co)polymer, having the surface thereof composed of acrylic fiber of a particulate and/or microfibrillar structures having a specific size, excellent in bulkiness and extensively used as beddings, clothes, etc. CONSTITUTION:The objective tow system spun yarn is constructed from acrylic fiber prepared by spinning a dope composed of, e.g. an acrylic (co)polymer and a solvent into a coagulation bath composed of 38-50wt.% nitric acid and water at a concentration within a range incapable of forming skin layers, and drawing the resultant spun dope in a drawing bath at a concentration within a range incapable of forming the skin layers and below a concentration capable of coagulating the dope. The above-mentioned acrylic fiber has the surface composed of a particulate and/or a microfibrillar structures having 0.01-0.5mum width and 0.05-10mum length and a fibrillar structure which is an aggregate of the aforementioned particulate and/or the microfibrillar structures and has 0.1-10mum width and >=50mum length. The modified cross section degree of the acrylic fiber is preferably 1.1-2.0.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to tow spinning systems. More specifically, the present invention relates to an acrylic spun yarn having excellent bulkiness.

[Prior art] Acrylic fibers are widely used in the clothing field such as knits and jerseys, bedding fields such as blankets, and indoor clothing fields due to their excellent durability and vivid coloring properties. With the diversification of needs, there is an extremely high demand for improved bulkiness.

[Problems to be Solved by the Invention] An object of the present invention is to develop an acrylic fiber tow spinning system with improved bulkiness.

[Means for Solving the Problems] The present inventors took advantage of the excellent durability and vivid coloring properties of acrylic fibers, and further developed a new technology to meet the demand for improved bulkiness that has come with the recent diversification of consumer needs. As a result of intensive research in response to these demands, we have developed a tow spun yarn with excellent bulkiness by using specific acrylic fibers and employing a tow spinning method.

That is, the present invention provides a tow spun yarn in which the fibers constituting the spun yarn are composed of an acrylonitrile polymer or an acrylonitrile copolymer, and the surface of the fibers has a width of 0.01 to 0.0. 5μm, length 0.0
Consisting of particulate and/or microfibrillar structures of 5 to 10 um and fibrillar structures of 0.1 to IO μm in width and 50 μm or more in length, which are aggregates of the particulate and/or microfibrillar structures. It is a tow spun yarn, which is an acrylic fiber.

The present invention will be explained in detail below.

The specific acrylic fiber used in the present invention and its manufacturing method are detailed in JP-A-61-119707. That is, the acrylic fiber used in the present invention is
When forming fibers by wet spinning using a dope prepared from an acrylonitrile polymer or acrylonitrile copolymer and its solvent, the dope is mixed with a solvent and a coagulant set within a concentration range that does not allow the formation of a skin layer. It can be obtained by a manufacturing method characterized by stretching in a stretching bath consisting of.

The acrylic fiber used in the present invention is a fiber composed of an acrylonitrile polymer or an acrylonitrile copolymer, and the acrylonitrile copolymer is
It contains 50% or more acrylonitrile, preferably 85% or more. Copolymerizable monomers include 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, vinyldicarboxylic acids and their esters such as itaconic acid and maleic acid, vinylidene halides such as vinylidene chloride, vinylpyridine and its N-substituted products Examples include sulfonic acid compounds such as vinylpyrrolidone, styrene, allylsulfonic acid, methallylsulfonic acid, and styrenesulfonic acid, and their salts, and two or more of these can also be used in copolymerization.

The acrylic fiber used in the present invention has a fiber surface with a width of 0.01 to 0.5 μm and a length of 0.05 to 10 m.
It is characterized by being composed of particulate and/or microfibrillar structures arranged in the fiber direction. In conventional acrylic fibers, such particulate and/or microfibrillar structures do not exist on the surface, and only streaks relatively parallel to the fiber axis are observed. The streaks seen in conventional acrylic fibers are interpreted to be due to wrinkles due to volumetric shrinkage of the acrylic fibers that occur during the drawing or heat treatment process, or, in the case of dry spun fibers, to be streaks caused by solvent evaporation traces caused by stretching. Ru. The particulate and/or microfibrillar structures of acrylic fibers used in the present invention are unique to the present invention and are formed by stretching gel particles generated by microphase separation during coagulation in the fiber axis direction during a drawing process. It is a structural feature. In conventional acrylic fibers, coagulation is performed in a coagulation bath with a skin layer-forming concentration lower than the skin layer-forming concentration range, so a dense and hard skin layer is formed on the fiber surface during coagulation. Surprisingly, when the spinning method described below is adopted, by coagulation and drawing, there are no voids of about 100 to 2000, which exist in conventional fibers during coagulation and drawing, and the fibers are essentially transparent. It was found that fibers were obtained.

The fibers suitable for the present invention have a fiber surface width of 0.05 to
It is formed of a particulate and/or microfibrillar structure with a diameter of 0.3 μm and a length of 0.5 to 10 μm, and its long axis is aligned in the direction of the fiber axis.

The presence of this particulate and/or microfibrillar structure can be detected using a commercially available scanning electron microscope (for example, JEOL Ltd., trade name JSM-35CF) at an accelerating voltage of 5 to 15 K.
v. It can be confirmed under observation conditions of 3000x to 30000x magnification.

Furthermore, the acrylic fiber used in the present invention has a surface composed of a fibrillar structure having a width of 0.1 to 10 μm and a length of 50 μm or more, which is formed by an aggregation of the particulate and/or microfibrillar structures. One of the characteristics of the structure is that The long axes of the fibrillar structures are arranged almost parallel to the fiber axis direction. The preferred width is 0.1
It is characterized in that fibrillar structures of 1-1 Oa are continuous in the fiber axis direction with a length of 100 μm or more. Although the existence of such fibrillar structures cannot be confirmed in conventional acrylic fibers, they are similar to the fibrillar structures of the present invention, which are thought to be formed by wrinkles due to volumetric contraction or traces of solvent evaporation, as described above. It is characterized by the presence of streaks. However, the continuity of this streak in the fiber direction is 50 μm or less for boat fishing, and is usually about 1 to 30 μm in most cases.

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 produced by spinning a dope prepared from an acrylonitrile polymer or an acrylonitrile copolymer and its solvent into a coagulation bath consisting of a solvent and a solidifying agent whose concentration is set within a range that does not allow the formation of a skin layer. Then, the film is obtained by stretching in a stretching bath consisting of a solvent and a coagulant whose concentration is set within a concentration range where skin layer formation is not possible and below a coagulable concentration.

Here, the concentration range in which the skin layer cannot be formed can be determined by a scanning electron microscope. The dope used for fiber formation is applied to a thickness of several micrometers to about 1 micrometer on a slide glass, and the slide glass is 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.

A necessary number of coagulation baths are prepared with varying concentrations so that the weight percentage of the solvent in the coagulation bath is 1%. After completion of coagulation, the product is washed with water, methanol, and air-dried to obtain a film-like product. The surface of this film is observed using an electron microscope at an acceleration voltage of 5 to 15 KV and a magnification of 1000 times. During observation, Au with a thickness of 50 to 500
coat the surface. According to this observation, if a skin layer is formed, at a magnification of 10,000 times,
The surface of the film was smooth with only some undulations and deposits observed. When the skin layer enters the unformable concentration range,
Pores of 0.05 to several tens of micrometers and 0.05 to 0.5 micrometers on the surface
Particles of about m size come to be observed. By this method, it is possible to determine the lower limit of the concentration range in which a skin layer cannot be formed.

The coagulation bath used in the wet spinning method for acrylic fibers used in the present invention is composed of a coagulant and a solvent capable of dissolving an acrylonitrile polymer or an acrylonitrile copolymer. Examples of solvents include concentrated aqueous solutions of inorganic salts such as rhodan salt, lithium bromide, zinc chloride, and aluminum perchlorate as inorganic solvents, and amide compounds such as dimethylformamide and dimethylacetamide, nitrile compounds, and dimethyl as organic solvents. Sulfone and sulfoxide compounds such as sulfoxide, thiocyanate compounds, nitro compounds, amino compounds, phosphorus compounds, carbonate compounds, and mixtures thereof are used. Coagulants include water, methanol, ethanol, acetone, acetic acid, ethylene glycol,
Carbon tetrachloride, xylene, benzene, etc. are used. The composition of coagulation baths used industrially is generally a combination of the above-mentioned solvent and water, 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.

Normally, the concentration of solvent in these coagulation baths is
A concentration range is used in which a skin layer is formed. this is,
This is because, when industrial productivity is taken into account, conditions are selected that provide excellent spinning stability and operability. In addition, in the concentration range in which skin layer formation is impossible, the coagulated fibers meander in the coagulation bath, resulting in a cloudy appearance and loss of transparency.
This is because there were problems such as a long time required for solidification.

The concentration range in which a skin layer cannot be formed varies depending on the type of solvent for the acrylonitrile polymer or acrylonitrile copolymer used in the coagulation bath, but when the coagulant is water, it is 38 to 50% by weight for nitric acid, dimethylformamide, dimethylacetamide, etc. For dimethyl sulfoxide, a range of 65 to 90% by weight is preferred, and for rhodan salt and zinc chloride, a range of 20 to 40% by weight is preferably used. This determination should be made using the scanning electron microscope described above.

The acrylic fiber used in the present invention is wound up from a coagulation bath and then further stretched in a stretching bath whose concentration is set to a range in which skin layer formation is impossible. Usually, the stretching 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 order to improve stretchability. Also, multi-stage stretching may be performed.

This stretching forms void-free, well-aligned microfibrils and fibrils in the acrylic fiber used in the present invention. If the stretching is not suitable, voids will occur within the fibers, microfibrils and fibrils will be imperfectly aligned, and physical properties will deteriorate.

The acrylic fibers used in the present invention are subjected to a normal water washing treatment to remove residual solvent to less than 0.1% based on the weight of the fibers. Furthermore, in order to increase physical properties such as strength, it may be re-stretched in hot water or steam.

Dry without tension or under tension to further remove moisture. Then, heat treatment is performed to increase stability. As a heat treatment method, a heating atmosphere such as pressurized steam, hot air, hot water, or on a hot plate is used.

The acrylic fiber used in the present invention has a degree of irregularity of 1.1 to 2.
It is preferably 0, and more preferably 1.3 to 1.6 because it exhibits better bulkiness.

The term "atypicality" as used herein is defined as follows.

The degree of heterogeneity (V) referred to herein is defined as below. The calculated diameter (rO ) divided by the denier (rO/ d = v
O), expressed as vl/vo=V.

Further, the acrylic fiber used in the present invention has a porosity of 10
% to 80%, and a porous structure having a porous structure of 20% to 80% is even more preferred since it exhibits better bulkiness.

The porosity (b) referred to herein is defined as below.

Diameter (r) of circumcircle of fiber cross section (500x enlarged photo)
is divided by the denier (d) (r/d-vl) and the calculated diameter (r
The value obtained by dividing O) by denier (I) (ro/d = vO
) divided by vO (vl-νO/vO)
It is expressed as Xl 00 =W(χ).

[Examples] All percentages in the examples are percentages by weight. In addition, in the present invention,
The bulkiness was measured according to the bulkiness measurement method of JIS L-1095.

CJL/keyability (cd/g)=40xSxH/NS is the metric count, H is the height, and N is the number of threads.

Example 1, Comparative Examples 1-2 Acrylonitrile 91.5%, methyl acrylate 8%,
O″C copolymer of 0.5% sodium methallylsulfonate
It was dissolved in a 167% nitric acid aqueous solution to prepare a 16% spinning stock solution. Next, this stock solution was prepared with a pore size of 0.4 an and a number of pores of 1000.
0 nozzle was used to extrude into the coagulation bath. At this time, the coagulation bath was a 42% nitric acid aqueous solution and the temperature was 5'C. Subsequently, the film was stretched 10 times in a stretching bath with a nitric acid concentration of 42% and a bath temperature of 70'C. The stretched fibers were washed with water, thoroughly dried in hot air at 130°C, and subjected to thermal relaxation treatment in steam at 120°C to obtain fibers with single yarn finenesses of 2 and 3 denier. As a result of observing the obtained fibers with a scanning electron microscope, it was found that the surface of the fibers had [0.1-0.2 μm,
It was observed that microfibrillar structures having a length of 0.5 to 3 μm were arranged in the fiber axis direction. In addition, the microfibrillar structures collectively have a width of 0.5 to 5 μm and a length of at least 100 μm in the fiber axis direction. It was observed that fibrillar structures with a length of ym or longer than 350 um were formed. The hook strength and elongation product of this fiber was 284, which was higher than 131 for a general acrylic fiber (trade name: Cashmilon, manufactured by Asahi Kasei Kogyo ■).

The 2-denier and 3-denier acrylic fibers obtained in this way and the general acrylic fiber (
Tow spinning was performed on Asahi Kasei Kogyo's (trade name: Cashmilon) and comparison was made with Sufu spun yarn.

The Sufu spun yarn is a 1152 meter count yarn that is 2 denier x 51 mm spun using a regular ring spinning machine. In addition, the tow spun yarn is a 2/34 meter count made by cutting 3 denier tow in a tow reactor and blending 40% sliver with a 20% shrinkage rate and 60% 3 denier x ■ (payas cut) non-shrinkable cotton. It is a worsted yarn. After dyeing these tow-spun yarns and staple-spun yarns, their rookie properties were measured and evaluated. The results are shown in Table 1.

(Left space below) Examples 2 to 4, Comparative Examples 3 to 6 Fibers with irregular cross sections as shown in Table 2 were produced by using the same acrylic fibers as in Example 1 but changing only the shape of the spinneret. It was evaluated in the same way. The results are shown in Table 2.

(Left below) Examples 5 to 7, Comparative Examples 7 to 10 A random copolymer containing ethylene oxide and propylene oxide in a weight ratio of 80:20 to 20:80 was added to the spinning stock solution, and the number average molecular weight was 10,000. Porous fibers as shown in Table 3 were produced in the same manner as in Example 1 except that 5 to 20% of polyalkylene glycol was added.

The obtained fibers are streak-like (straw-like) along the length.
It was porous with pores. The evaluation results are shown in Table 3.

(Hereinafter, blank spaces) C Effects of the Invention The tow spinning system of the present invention is an acrylic spun yarn with unprecedented bulkiness.

Patent applicant: Asahi Kasei Industries, Ltd.

Claims (1)

[Claims] 1. In tow spun yarn, the fibers constituting the spun yarn are
A fiber composed of an acrylonitrile polymer or an acrylonitrile copolymer, and the surface of the fiber has a particulate and/or microfibrillar structure with a width of 0.01 to 0.5 μm and a length of 0.05 to 10 μm. Tow spun yarn is an acrylic fiber composed of a fibrillar structure having a width of 0.1 to 10 μm and a length of 50 μm or more, which is an aggregate of the particulate and/or microfibrillar structure.