JPH0457911A - Porous actylic yarn having excellent water retention and its production - Google Patents

Abstract

PURPOSE:To obtain the title yarn useful as underwear, etc., having excellent gloss and physical properties of yarn, by spinning the spinning dope of a polymer mixture comprising an acrylonitrile-based polymer and cellulose acetate, shrinking and further extracting and removing cellulose acetate in the yarn with a solvent. CONSTITUTION:A polymer mixture comprising 50-85wt.% acrylonitrile-based polymer containing >=85wt.% acrylonitrile and 50-15wt.% cellulose acetate is dissolved in a solvent to give a spinning dope, which is spun, drawn at 2-5 times, dried, relaxed and shrunk at >=5%. Further >=55wt.%, preferably >=90% cellulose acetate in the yarn is extracted with a solvent and removed to give the objective yarn consisting of >=92.5wt.% acrylonitrile-based polymer and <7.5wt.% cellulose acetate and having >=30% water retention ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an acrylic fiber with good water retention properties and a method for producing the same.

More specifically, after spinning, stretching and drying a mixed solution containing an acrylonitrile polymer and cellulose acetate, the yarn has excellent gloss and is obtained by selectively extracting and removing only the cellulose acetate with a solvent. The present invention relates to a porous acrylic fiber having physical properties and a high water retention rate, and a method for producing the same.

[Prior Art] Acrylic fibers are being used in a wide range of products for clothing such as underwear, sportswear, and bedding, taking advantage of their excellent color development, heat retention, and light resistance.

In recent years, in addition to these properties, there has been a demand for additional functions such as antistatic properties, water absorbing properties, water retaining properties, and deodorizing properties. Generally, synthetic fibers are inferior to natural fibers in terms of water absorption and water retention, and acrylic fibers are no exception.

Various studies have been made to improve the water absorption and water retention properties of acrylic fibers, and in particular, in wet spinning, mild drying conditions have been selected as in Japanese Patent Publication No. 48-6649 and Japanese Patent Publication No. 48-6650. There is also a method of obtaining porous acrylic fibers, and a method of regenerating voids by dissolving a water droplet compound filled in the swollen gel dow in a post-process as disclosed in Japanese Patent Publication No. 48-8285 and Japanese Patent Publication No. 48-8286. A method for doing so is disclosed.

Similarly, by mixing, dissolving, and wet spinning a polymer made of acrylonitrile-based polymer and cellulose acetate,
Japanese Patent Publications No. 31-968 and No. 33-2 disclose fibers in which voids are generated in the cross section of the fibers to impart hygroscopicity and water absorption properties.
There are publications such as Publication No. 317. The present inventors also applied for patent application No. 2-292
Publication No. 04 discloses that by examining the composition of acrylonitrile polymer, etc., it is possible to obtain excellent texture, thread properties, and water retention in dry-processed acrylic fibers that conventionally had low water retention.

[Problem to be solved by the invention] However, Japanese Patent Publication No. 31-968, Japanese Patent Publication No. 33
In the method disclosed in Publication No. 2317, even if the mixing ratio of cellulose acetate is increased to 50% by weight, the water retention rate of the fiber obtained is at most about 25%, resulting in decreased stretchability and shrinkage during drying relaxation treatment. Due to the decrease, sufficient yarn physical properties cannot be obtained, and there is also a problem in passing through subsequent processes such as spinning. Further, the water retention rate of the fiber obtained by the method disclosed in Japanese Patent Application No. 2-29204 is at most 35%.

As a result of further studies, the present inventors found that acetic acid in fibers obtained by spinning, stretching, and drying a spinning dope prepared by dissolving and mixing an acrylonitrile polymer and cellulose acetate in a specific composition range. By selectively removing only cellulose, we have been able to provide fibers that have a water retention rate as high as 30 to 80%, which was previously unobtainable, and have improved yarn properties.

[Means for Solving the Problems] That is, the present invention provides: (1) 9 containing 85% by weight or more of acrylonitrile;
It is composed of 2.5% by weight or more of acrylonitrile polymer and less than 75% by weight of cellulose acetate, and has a water retention rate of 30%.
% or more of porous acrylic fibers with good water retention properties.

f2 A polymer mixture consisting of 50 to 85% by weight of an acrylonitrile polymer containing 185% by weight or more of acrylonitrile and 50 to 15% by weight of cellulose acetate is dissolved in a solvent, a mixed spinning stock solution is spun, and then 2 to 5 times Production of porous acrylic fibers with good water retention, characterized by stretching the fibers, subjecting them to shrinkage of 5% or more through drying relaxation treatment, and further extracting and removing 85% or more of the cellulose acetate in the fibers with a solvent. Method.

The main points are as follows.

The present invention will be explained in more detail below.

The acrylonitrile polymer that is the object of the present invention must contain at least 85% by weight of acrylonitrile. If the content of acrylonitrile is less than this, it is not preferable because the physical properties of the fiber necessary for clothing fibers, especially the shape stability, will deteriorate. Examples of monomers copolymerizable with acrylonitrile include (meth)acrylic acid esters such as methyl acrylate and methyl methacrylate, vinyl acetate, styrene, and acrylamide. The copolymerization rate of these is usually 3 to 1.
It is 0% by weight. Further, in order to improve dyeability, (meth)acrylic acid, (meth)allylsulfonic acid, vinylbenzenesulfonic acid and their salts, dimethylaminoethyl (meth)acrylate, and vinylpyridine may be copolymerized. The copolymerization rate of these monomers is usually 3% by weight or less.

The polymer can be produced by any conventional method such as suspension polymerization, solution polymerization, emulsion polymerization, etc.

The degree of polymerization of a polymer is its specific viscosity (0.1 g of polymer
．． 0.1 (dissolved in 100 mβ of dimethylformamide containing 1N rhodan soda and measured at 25°C)
A range of 0 to 0.20 is preferred.

The cellulose acetate used in the present invention is cellulose diacetate or cellulose triacetate.

Furthermore, in addition to the acrylonitrile polymer and cellulose acetate, it is of course possible to add plasticizers, self-seistance improvers, heat stabilizers, titanium oxide, etc. for the purpose of improving spinnability, drawability, and yarn properties. .

As the spinning solvent used in the present invention, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, etc., which are common solvents for acrylonitrile polymers and cellulose acetate, are used, and these organic solvents are preferable from the viewpoint of ease of solvent recovery. used.

Although the method of mixing the acrylonitrile polymer and cellulose acetate is not particularly limited, it is necessary that the concentration of the polymer in the mixed stock solution be 20 to 40% by weight.

The spinning method may be any of the wet, dry-wet, and dry methods that are normally employed in the production of acrylic fibers, but it is preferable that a dense fiber structure be formed during spinning, so that it can be easily used in the spinning process, subsequent drawing process, etc. Dry spinning is desirable because it can avoid fibrillation on the fiber surface and the accompanying shedding of cellulose acetate.

The ratio of cellulose acetate in the undrawn yarn after spinning is 1
If the amount is less than 5% by weight, sufficient extraction cannot be carried out during the subsequent extraction and removal of cellulose acetate, and fibers with high water retention of 30% or more as defined in the present invention cannot be obtained. On the other hand, if it exceeds 50% by weight, the water retention rate will be higher, but the strength and elongation will be lowered due to a decrease in the drawability of the undrawn yarn and a decrease in shrinkage during drying relaxation treatment.
It has poor yarn properties such as knot strength and elongation, making it difficult to use as clothing.

Strength is imparted to the undrawn yarn by drawing it in hot water. The stretching temperature is preferably 80 to 95°C, and the stretching ratio is preferably 2 to 5 times. If the stretching ratio is less than 2 times, sufficient strength will not be imparted to the resulting fibers and fluff will frequently occur during the spinning process, etc.
Post-processability becomes poor. On the other hand, if it exceeds 5 times, fibrillation on the fiber surface becomes noticeable and yarn breakage occurs. The higher the proportion of cellulose acetate in the undrawn yarn, the lower the stretching ratio.

The undrawn yarn is washed in hot water at the same time as or before or after the drawing process. Washing temperature is 80 to 100℃
is preferred. The stretched and washed fiber bundle is coated with an oil agent and then subjected to drying and relaxation treatment. Although there are no particular limitations on the method of drying and relaxing, the present inventors have tested the fiber bundles after stretching and washing at a relative humidity of 10% in a moist state without tension.
to 40% and a temperature of 130 to 160° C. under heated air to dry and relax at the same time. The fibers are relaxed by 5% or more using the method described above. If the shrinkage rate is less than 5%, the yarn physical properties such as knot strength and elongation are poor, and the retraction structure for spinning etc. becomes poor.

The fibers subjected to the dry relaxation treatment are subjected to solvent extraction removal treatment of cellulose acetate immediately after the dry relaxation treatment or after spinning, knitting and weaving. The extraction rate of cellulose acetate needs to be 85% or more, preferably 90% or more. Extraction rate is 85
If the amount is less than %, cellulose acetate remains on the surface of the fibers, resulting in a hard texture and making them unsuitable for clothing.

Surprisingly, the physical properties of the fiber obtained after the extraction and removal of cellulose acetate hardly deteriorated, and the yarn quality required for spinnability, such as knot strength and elongation, was significantly improved compared to that before the extraction and removal. This is what is happening. Although the detailed cause is unknown, volume shrinkage in the cross-sectional direction of the fibers and a network structure due to the acrylonitrile polymer were observed in the fibers after extraction and removal, and it is presumed that this contributes to the improvement of yarn quality.

The solvent used in this extraction and removal process is not particularly limited as long as it selectively dissolves cellulose acetate; specifically, in the case of cellulose diacetate, acetone, methyl ethyl ketone, methylene chloride, methyl acetate, dioxane, etc. , for cellulose triacetate, methylene chloride, chloroform,
Examples include methyl acetate and dioxane.

EXAMPLES The present invention will be specifically explained below with reference to Examples.

The water retention rate of the obtained fibers was measured by the following method. % in the examples indicates weight % unless otherwise specified.

<Water retention rate> After scouring fibers by a conventional method and soaking them in ion-exchanged water for 24 hours, the raw cotton was dehydrated by centrifugation for 10 minutes at an acceleration of 100 OG, and the weight (Wl) of the raw cotton was measured. This fiber is 1
After drying with hot air at 05° C. for 3 hours and cooling in a desiccator for 30 minutes, the weight (W2) was measured and the water retention rate was calculated according to the formula below.

[Example] Example 1 Acrylonitrile copolymer 90 to 90 and having a specific viscosity of 0.175 (0.1% dimethylformamide (DMF) solution, measured at 25% °C) consisting of 93% by weight of acrylonitrile and 7% by weight of vinyl acetate. 40% by weight and 10 to 60% by weight of cellulose diacetate (oxidation degree 55%) were dissolved in dimethylformamide and mixed to prepare a stock solution with a solid content concentration of 28%.

1) The above stock solution was heated to 0° C. and then discharged into an inert gas heated to 230° C. through an orifice having 600 holes and a hole diameter of 015 mlffφ to obtain an undrawn yarn. This undrawn yarn was converged into a fiber bundle of 200,000 deniers, and was placed in hot water with a
After stretching the fiber bundle to 4.0 times or more, washing it in hot water, and applying an oil agent, the resulting fiber bundle is heated at a relative humidity of 40% without tension.
A drying/relaxation treatment was performed at a temperature of 150°C. Furthermore, the obtained fibers were thoroughly washed in an acetone bath, and the yarn physical properties and water retention rates of each obtained fiber are shown in Table 1.

Example 2 Acrylonitrile 93.5% by weight, methyl acrylate 6
wt%, specific viscosity 0.161 (0.1% DMF solution, 25%
Acrylonitrile copolymer (measured at ℃) 90 to 10
% by weight and 10 to 90% by weight of cellulose diacetate (degree of acetylation 55%) were dissolved in dimethylformamide and mixed to prepare a stock solution with a solid content concentration of 30%.

The above stock solution was heated to 130° C. and then discharged into an inert gas heated to 230° C. through an orifice with 600 holes and a hole diameter of 0.15 φ to obtain an undrawn yarn. The undrawn yarns are converged to form a fiber bundle of 200,000 denier, stretched 2.0 to 4.0 times in hot water, washed in hot water, and coated with an oil agent. 40% relative humidity under no tension,
Drying/relaxation treatment was performed at a temperature of 150°C. Furthermore, the obtained fibers were thoroughly washed in a hot acetone bath, and the yarn physical properties and water retention rates of each obtained fiber are shown in Table 2.

Example 3 Acrylonitrile 93.5% by weight, methyl acrylate 6
wt%, specific viscosity 0.161 (0.1% DMF solution, 25%
Acrylonitrile copolymer (measured at ℃) 70 to 50
% by weight and 30 to 50% by weight of cellulose diacetate (oxidation degree 55%) were dissolved in dimethylformamide and mixed to prepare a stock solution with a solid content concentration of 30%.

The above stock solution was heated to 130° C. and then discharged into an inert gas heated to 230° C. through an orifice having 600° holes and 0.15 i1 φ diameter to obtain an undrawn yarn. This undrawn yarn was converged into a fiber bundle of 200,000 deniers, and was placed in hot water with a
After stretching the fiber bundle to 4.0 times or more, washing it in hot water, and applying an oil agent, the resulting fiber bundle is heated at a relative humidity of 40% without tension.
A drying/relaxation treatment was performed at a temperature of 150°C. Furthermore, cellulose diacetate was removed from the obtained fibers in a hot acetone bath without changing the extraction rate, and Table 3 shows the results of evaluating the water retention rate and texture of each fiber obtained.

[Effect of the invention] The fiber according to the invention has excellent gloss and thread properties,
Moreover, it provides a new porous acrylic fiber that has high water retention properties that could not be obtained with conventional acrylic fibers, and a method for producing the same.It is expected to be widely used in underwear and clothing, and its industrial significance is high. is big.

Claims (2)

[Claims] (1) 9 containing 85% by weight or more of acrylonitrile
2.5% by weight or more of acrylonitrile polymer and 7.5% by weight
Composed of less than % by weight of cellulose acetate and has a water retention rate of 3
A porous acrylic fiber with good water retention, characterized by having a water retention capacity of 0% or more. (2) A spinning stock solution prepared by dissolving and mixing a polymer mixture of 50 to 85% by weight of an acrylonitrile polymer containing 85% by weight or more of acrylonitrile and 50 to 15% by weight of cellulose acetate in a solvent is spun, and then 2 A porous acrylic type material with good water retention, which is characterized by stretching the fiber to 5 times or more, shrinking it by 5% or more through drying relaxation treatment, and further extracting and removing 85% or more of the cellulose acetate in the fiber with a solvent. Fiber manufacturing method.