JPH09273029A - Splitting conjugate fiber and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a splitting conjugate fiber capable of easily and stably obtaining a superfine fiber by treating with a weak alkali, excellent in DMF resistance and suitable for artificial leathers, etc., by drawing a splitting conjugate fiber containing a specific alkali soluble polymer as one component and heat treating the fiber. SOLUTION: This splitting conjugate fiber is obtained by drawing a splitting conjugate fiber as one component comprising a weal alkali soluble polymer, which consists of a copolyester comprising terephthalic acid and ethylene glycol as main constituent ingredients and containing preferably 6-12mol% (based on the total acid component) of 5-sodium sulfoisophthalic acid and preferably 0-10mol% of isophthalic acid, then heat treating the drawn fiber with hot water or steam. It is preferable to split the splitting conjugate fiber into >=2 threads by treating the fiber with a weak alkali and bring the denier of the fiber after splitting to <=1 denier.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD [0001] The present invention is useful as a base material for artificial leather and the like composed of ultrafine fibers and polyurethane,
TECHNICAL FIELD The present invention relates to a comminuted conjugate fiber which can be easily and stably made into ultrafine particles, and a method for producing the same. More specifically, D, which is a solvent for polyurethane, can be made extremely fine by treatment with a weak alkali.
The present invention relates to a thinnable conjugate fiber that is not easily attacked by MF and a method for producing the same.

[0002]

2. Description of the Related Art Ultrafine fibers are used for artificial leather or the like by imparting polyurethane by taking advantage of the characteristics of surface quality and tactile sensation, and their development in this field is active.

Most of these ultrafine fibers are obtained by a method in which a composite fiber of different components is formed into a cloth, and then separation separation treatment or one component is dissolved and removed. Further, the application of polyurethane is carried out in the state of the fabric of the composite fiber, and by applying the polyurethane to the fabric of the composite fiber and then making it very thin,
This is a structure in which the ultrafine fibers and the polyurethane do not directly adhere to each other, and an excellent fabric texture is obtained.

Many proposals have been made for more stable and easy means for performing ultrafine means such as separation and separation for obtaining ultrafine fibers from composite fibers or dissolving and removing one component, and ultrafine means suitable for the processing step of the product. Has been done.

In particular, an organic solvent has been conventionally used as a means for dissolving and removing one component for the purpose of making it ultrafine, but means using hot water or an alkali is being considered from the viewpoint of environmental problems and costs.

[0006] Examples of the ultrafine means using hot water include:
A technique of a composite fiber using a water-soluble polymer is disclosed in JP-A-3-
It is disclosed in Japanese Patent Laid-Open No. 213564 and Japanese Patent Laid-Open No. 5-247725. Although these composite fibers can easily and stably obtain ultrafine fibers by dissolving and removing one component with hot water, the hot water-soluble component also dissolves in DMF which is a solvent for polyurethane in the step of applying polyurethane. Therefore, DMF-based polyurethane can be substantially used because of the problem that the surface of the fabric becomes a seal and the polyurethane does not enter, let alone the uniform application of polyurethane to the fabric using the composite fiber. There wasn't.

On the other hand, a technique for producing ultrafine fibers by utilizing the difference in alkali solubility is disclosed in, for example, Japanese Patent Application Laid-Open No. 54-6965. However, in the case of using a dissolved component specification with increased alkali solubility, DM
There was a problem in that a part of the dissolved component was dissolved in F, and the fibers were stuck together, and the uniformity of the imparting of polyurethane was problematic. Further, if DMF having a strong alkali-soluble property that does not cause a problem is used, the polyurethane may be deteriorated by the ultrafine treatment with alkali, or it may be difficult to divide into uniform ultrafine fibers, which is not always satisfactory. There wasn't.

That is, there is a limit to the provision of the conjugate fiber which can use the DMF type polyurethane without any trouble and can easily obtain stable ultrafine fibers.

[0009]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems of the prior art,
An object of the present invention is to provide a thinnable conjugate fiber having DMF resistance that allows the use of DMF-based polyurethane and capable of easily and stably obtaining ultrafine fibers.

[0010]

Means for Solving the Problems The constitution of the thinnable conjugate fiber of the present invention which achieves the above object is a weak alkali-soluble compound which is divisible by a weak alkali and is substantially insoluble in DMF. The present invention is characterized in that the organic polymer is contained as one component.

Further, the constitution of the method for producing a comminuted conjugate fiber of the present invention comprises a copolymerized polyester containing terephthalic acid and ethylene glycol as main components and containing 5-sodium sulfoisophthalic acid and isophthalic acid. It is characterized in that the thinnable conjugate fiber containing the weak alkali-soluble polymer as a component is stretched and then heat-treated.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

First, the thinnable conjugate fiber according to the present invention will be described.

The thinnable conjugate fiber in the present invention is made of a polymer of at least two components and has a well-known broadly-defined sea-island type or split type cross-sectional morphology, and peeling splitting or dissolution of one component. It is a fiber that can be divided into at least two or more fibers by removal, and has a fineness of 1 denier or less after division, more preferably 0.5 denier or less and can be made into ultrafine fibers.

One component of this comminuted conjugate fiber consists of a weakly alkali-soluble polymer. This weakly alkali-soluble polymer is preferably a polymer that normally dissolves in caustic soda at a concentration of 2% or less at a temperature of 98 ° C. or less and within 60 minutes.

Polymers satisfying the above requirements include 5-
Mention may be made of sodium sulfoisophthalic acid and copolyesters containing isophthalic acid.

The amount of copolymerization is 6 to 12 m of the total acid component.
ol% 5-sodium sulfoisophthalic acid, and 0
A copolyester containing 10 to 10 mol% of isophthalic acid is preferable. Note that isophthalic acid may not be included. If the copolymerization amount exceeds the above range and the polymer composition is too high, the DMF resistance is insufficient even if the heat treatment of the present invention is performed, and the weakly alkali-soluble component is partially eluted or the component is softened. Fiber sticking,
It becomes difficult to use DMF-based polyurethane substantially. On the other hand, when the polymer composition is less than the copolymerization amount range, even if the DMF-based polyurethane can be processed, it is difficult to make it extremely thin by weak alkali treatment. Become.

The first point of the present invention is to use a component which is easily dissolved in a weak alkaline hot water as a dissolved component of the composite fiber. The composite fiber using this component has poor DMF resistance, and if it is immersed in DMF as it is, a part of the dissolved component is eluted or the fiber is stuck, so the heat treatment in the present invention is required.

As the other component which becomes the ultrafine fiber of the thinnable conjugate fiber according to the present invention, a polymer capable of melt spinning can be arbitrarily applied without particular limitation. For example, polyamides such as nylon 6, nylon 66, nylon 12 and copolymer nylon, polyesters such as polyethylene terephthalate, copolymer polyethylene terephthalate, polybutylene terephthalate and copolymer polybutylene terephthalate, and polyolefins such as polyethylene and polypropylene are used. Of these, polyamide and polyester polymers are particularly preferable in terms of physical properties and dyeability. In addition, these other components can be used without being limited to one kind. Further, if necessary, additives such as a matting agent, a stabilizer, an antistatic agent, and a flameproofing agent may be added.

Next, a method for producing the thinnable composite fiber according to the present invention will be described.

First, the weak alkali-soluble polymer and the other polymer to be the ultrafine fibers are independently melted, and then the weak alkali-soluble polymer forms a fiber cross section occupying at least a part of the surface of the composite fiber. , For example, the weak alkali-soluble polymer is placed in the sea part and the other polymer is placed in the island part, or the other polymer is divided by the weak alkali-soluble polymer so that the two are merged to form a compostable composite. It is made into fibers, discharged from the discharge holes of the spinneret, drawn at high speed, and drawn to obtain composite fibers.

An important point of the present invention is to make it possible to process the thus obtained conjugate fiber into a DMF-based polyurethane without trouble.

When this composite fiber is dipped in a DMF solution as it is, a weakly alkaline soluble component is partially eluted or swells to cause fiber sticking, which makes it impossible to uniformly apply polyurethane. Therefore, finally, how to improve the DMF resistance without impairing the alkali solubility becomes a problem.

The essential point of the present invention for solving the above-mentioned problems is to heat-treat the melt-spun composite fiber after stretching it.

This heat treatment is not particularly limited, but the wet heat condition is hot water of 90 ° C. or higher, or steam for preferably 10 seconds or longer, or the dry heat condition is hot roll, hot plate, heated air, etc. It is preferable to carry out the treatment at 130 ° C. or higher for preferably 30 seconds or longer.

If the heat treatment is carried out under conditions that are far below these conditions, the crystallization of the fibers will not sufficiently occur, making it difficult to obtain the target DMF resistance, and even if the temperature is too high, hydrolysis and thermal decomposition will occur. However, as a guideline, about 130 ° C for wet heat and 230 ° C for dry heat are recommended. Generally, in the case of wet heat, dipping in a hot water bath at 90 ° C to boiling is preferable, and in the case of dry heat, treatment with hot air at 130 to 200 ° C is preferable. By increasing the crystallization of the fiber by the heat treatment, the dissolution of the dissolved component in DMF is substantially eliminated, the swelling of the fiber is not changed, and the target composite fiber having excellent DMF resistance can be obtained.

This heat treatment may be performed continuously with the stretching. However, since a long treatment zone is required, and the physical properties of the drawn yarn, particularly in this case, the composite fiber is likely to have low shrinkage, and the shrinkage treatment effect for wrinkling and densification of the fabric may be poor. It is more preferable to perform the heat treatment after forming a cloth such as a non-woven fabric. In addition, this heat treatment can obtain almost the same effect in both tension setting and free treatment.

The thus obtained thinnable conjugate fiber of the present invention is used as a woven or knitted fabric or a non-woven fabric by mixing with other fibers, and is applied to a wide range of applications such as artificial leather to which polyurethane is added. Is possible.

When the composite fiber is used, an ultrafine fiber can be obtained by subjecting it to a dissolution treatment with a weak alkali. This dissolution treatment can be performed continuously by installing a special treatment tank, but the usual higher-order processing steps, that is, the desizing and scouring step, and dyeing methods such as wince and circular are used. It is also possible to carry out dissolution treatment. It is particularly preferable to use an alkali decomposition accelerator or an auxiliary agent for desizing and refining, that is, a surfactant or an anti-redeposition agent.

Since the treatment is carried out with a weak alkali, even if the ultrafine fibers are of a polyester type in which the ultrafine fibers are corroded by a strong alkali, the ultrafine fibers can be made ultrafine without adversely affecting the ultrafine fibers. Further, since it can be processed without using a chemical such as an organic solvent, it goes without saying that no special equipment such as a pressure-sealed type or local exhaust is required, and there is no problem in terms of safety and environment hygiene.

[0031]

The present invention will be described below in more detail with reference to examples.

Example 1 Copolymerized polyethylene terephthalate containing 8 mol% of 5-sodium sulfoisophthalic acid and 1 mol% of isophthalic acid as a weakly alkali-soluble polymer was used as another polymer component for forming ultrafine fibers, and homopolyethylene was used. Each of terephthalates dried under reduced pressure was used.

Both components were each melted in a screw extruder,
Each was weighed with a gear pump and sent to a composite spinneret for spinning. The composite base was a multi-island sea-island type, and the weak alkali-soluble polymer was used as the sea component and homopolyethylene terephthalate was used as the island component, and the composition ratio was 50% sea component and 50% island component.

The obtained undrawn yarn is drawn and crimped,
Through the cutting, a staple of the compostible composite fiber was obtained.
Further, this staple was passed through a card, a cross wrapper and a pre-punch M / C, and then needle punched using a needle board to obtain an entangled sheet.

This sheet was subjected to dry heat treatment at 150 ° C. for 3 minutes in a hot air dryer, then immersed in a DMF solution at 25 ° C. for 2 minutes and taken out. There was no change on the fiber surface, and after washing with water, drying and weighing, there was no change in weight.

Next, this sheet was treated with an alkaline solution of NaOH 0.9% at 90 ° C. for 10 minutes. Then, it was thoroughly washed with hot water and dried. The change in weight due to this treatment was 50% less than before treatment. When the cross section of the fiber was observed, all the fibers were 0.05 denier (the denier before melting was 3.6 d, and the number of divisions was 36), which were very fine yarns, and had a good feel to the touch.

Example 2 The entangled sheet of Example 1 was subjected to wet heat treatment for 1 minute in boiling water at 98 ° C. or higher. Then, it was immersed in a DMF solution at 25 ° C. for 2 minutes and taken out. There was no change on the fiber surface, and the weight was the same as before weighing and dipping after washing with water and drying.

The sheet treated with boiling water was dipped in a DMF solution of polyurethane to allow 24% of solid content to adhere to the total amount of fibers, and then wet coagulate. When this sheet was observed, no sticking between fibers was observed, and polyurethane was uniformly present on the sheet surface and in the cross-sectional direction.

Next, alkali treatment was carried out according to Example 1, and it was confirmed that all the fibers were extra fine yarn of 0.05 denier.

Comparative Example 1 The entangled sheet of Example 1 was taken out by immersing it in a DMF liquid at 25 ° C. for 2 minutes without heat treatment. The fibers were slightly swollen and felt slimy. When it was washed with water, dried and weighed, the weight loss was 2.1% of that before immersion.

The entangled sheet was provided with DMF-based polyurethane as in Example 2, and the processed sheet was observed. Adhesion between fibers was observed in some parts, and the polyurethane had a slight tendency in the central part.

[0042]

EFFECTS OF THE INVENTION The thinnable conjugate fiber of the present invention can use DMF type polyurethane which is generally used in producing artificial leather composed of ultrafine fibers and polyurethane. After applying, it is possible to easily and stably obtain ultrafine fibers by treatment with a weak alkali, and therefore it can be suitably used for artificial leather and the like.

Claims (11)

[Claims] 1. Dividable with a weak alkali, and D
A comminuted conjugate fiber comprising a weakly alkali-soluble polymer that is substantially insoluble in MF as one component. 2. The comminuted conjugate fiber according to claim 1, wherein the other component of the comminuted conjugate fiber which becomes the ultrafine fiber is a melt-spinnable polymer. 3. A weakly alkali-soluble polymer has terephthalic acid and ethylene glycol as main constituent components, and
The comminuted conjugate fiber according to claim 1 or 2, which is composed of a copolyester containing sodium sulfoisophthalic acid and isophthalic acid. 4. Copolymerized polyester is 6 per total acid component.
~ 12 mol% 5-sodium sulfoisophthalic acid,
4. The thinnable conjugate fiber according to claim 3, which contains 0 to 10 mol% of isophthalic acid. 5. The millable composite fiber is treated with a weak alkali,
The at least 2 or more division | segmentation, and the fineness after division | segmentation is 1 denier or less, The micronizable conjugate fiber in any one of Claims 1-4 characterized by the above-mentioned. 6. The thinnable conjugate fiber according to claim 1, which is used for processing a DMF-based polyurethane. 7. A micronizable composite comprising terephthalic acid and ethylene glycol as main constituents and a weak alkali-soluble polymer composed of a copolyester containing 5-sodium sulfoisophthalic acid and isophthalic acid as one component. A method for producing a thinnable composite fiber, which comprises subjecting the fiber to heat treatment and then subjecting it to heat treatment. 8. Copolymerized polyester is 6 per total acid component.
~ 12 mol% 5-sodium sulfoisophthalic acid,
8. The method for producing a thinnable conjugate fiber according to claim 7, which further comprises 0 to 10 mol% of isophthalic acid. 9. The method for producing a thinnable conjugate fiber according to claim 7, wherein the heat treatment is hot water treatment at 90 ° C. or higher or steam treatment. 10. The method for producing a comminuted conjugate fiber according to claim 7, wherein the heat treatment is a dry heat treatment at 130 ° C. or higher. 11. The thinnable conjugate fiber is divided into at least two or more pieces by a weak alkali treatment, and the fineness after division is set to 1 denier or less. A method for producing the comminuted conjugate fiber described.