JPH09250023A - Production of finely dividable conjugate fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for bath drawing of finely dividable conjugate fiber, enabling the high temperature bath drawing, the good staple drawing and the easy stable fine dividing of a conjugate fiber, which is difficult in bath drawing as it is, without lowering weak-alkali solubility when a conjugate fiber, composed of a weak-alkali-soluble component, is drawn in a bath and to produce a conjugate fiber capable of producing ultrafine fibers in an easy and stabile manner. SOLUTION: This finely dividable conjugate fiber is composed of constituting components mainly comprising terephthalic acid and ethylene glycol and a component comprising a weak-alkali-soluble polymer consisting of a copolymer ester containing 6-12mol% of 5-sodium sulfoisophthalic acid and 0-10mol% of isophthalic acid based on the total acid components. For drawing the finely dividable conjugate fiber in a bath, the fiber is subjected to a primary drawing in a bath below 65 deg.C or with dry heat at 60-120 deg.C, and subsequently the resultant fiber is drawn in a bath of >=65 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid bath drawing method of a thinnable conjugate fiber which can be easily and stably made into ultrafine particles.

[0002]

2. Description of the Related Art Ultrafine fibers have been actively applied to artificial leather and the like by taking advantage of their surface quality and tactile sensation.

For many of these ultrafine fibers, a method in which a composite fiber of different components is made into a cloth and then separated and divided, or one component is dissolved and removed to make it ultrafine is used. And an ultrafine means such as this separation division or dissolution removal of one component,
Many proposals have been made for more stable and easy implementation of ultrafine means suitable for the processing steps of products.

In particular, an organic solvent has been conventionally used for dissolving and removing one component for the purpose of making it ultrafine, but from the viewpoint of environmental problems and cost, means using hot water or alkali has been studied. As the means for making ultrafine by hot water,
For example, a technique of a composite fiber using a water-soluble polymer is disclosed in JP-A-3-213564 and JP-A-5-247725. Although these composite fibers can easily and stably obtain ultrafine fibers by dissolving and removing one component with hot water, they become ultrafine fibers at the time when hot water is used during the fiber manufacturing process, or the fibers are stuck together. And so on,
Since hot water cannot be used practically, dry heat drawing is inevitable.

Therefore, when forming a staple, a commonly used liquid bath and steam drawing cannot be performed, which is a serious problem in terms of thermal efficiency, workability, and uniformity of staple.

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 improved solubility, it is difficult to divide into uniform ultrafine fibers if the fiber bath sticks to each other in liquid bath drawing or if there is no problem in liquid bath drawing. It was not always satisfactory.

That is, there has been a limit to the provision of composite fibers which can be drawn in a liquid bath and can easily obtain stable ultrafine fibers.

[0008]

The present invention does not have the drawbacks of the prior art as described above, that is, it can be stretched in a liquid bath, and ultrafine fibers can be easily and stably obtained. The purpose is to provide fibers.

[0009]

The method for producing a thinnable composite fiber of the present invention has the following constitution in order to solve the above problems.

That is, terephthalic acid and ethylene glycol are the main constituents, and the total acid component is 6-12.
mol% 5-sodium sulfoisophthalic acid and 0
When liquid-stretching the thinnable conjugate fiber having a weakly alkali-soluble polymer, which is a copolyester containing 10 mol% of isophthalic acid as one component, in a liquid bath, a liquid bath of less than 65 ° C or a dry bath of 60 to 120 ° C is used. This is a method for producing a thinnable conjugate fiber, which comprises first drawing with heat and then drawing in a liquid bath at 65 ° C. or higher.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

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

The thinnable fiber in the present invention is composed of a polymer of at least two components and can have various sea-island type or split type cross-sectional shapes. The micronizable fiber of the present invention is a fiber that can be made into ultrafine fibers of preferably 1 denier or less, more preferably 0.5 denier or less by peeling splitting or dissolving and removing one component.

One component of this comminuteable fiber is a weakly alkaline soluble polymer. The weakly alkali-soluble polymer used in the present invention refers to a polymer which dissolves within 60 minutes at a concentration of caustic soda of 2% or less and a temperature of 98 ° C. or less.

The polymer satisfying the above conditions is 6 to 12 m.
ol% 5-sodium sulfoisophthalic acid and 0-
It is a copolyester containing 10 mol% of isophthalic acid. When the polymer composition exceeds this copolymerization amount, there is a problem that even if the liquid bath drawing in the present invention is carried out, fiber elution occurs due to partial elution or softening of the components, making liquid bath drawing substantially impossible. is there. On the other hand, when the polymer composition is less than this copolymerization amount, there is a problem that even if the solution is drawn in a liquid bath, it is impossible to make it ultrafine by a weak alkali treatment.

The point of the present invention is to use a component that is easily dissolved in hot water of weak alkali as the dissolved component of the composite fiber. The conjugate fiber using this component has poor hot water resistance in the undrawn yarn state, and the fiber will stick when it is drawn in a normal high temperature liquid bath as it is. Therefore, the present invention can prevent the fiber from sticking.

There are no particular restrictions on the other components that form the ultrafine fibers of the thinnable fibers of the present invention, and any polymer capable of melt spinning can be used. For example, polyamide such as nylon 6, nylon 66, nylon 12, copolymer nylon, polyethylene terephthalate, copolymer polyethylene terephthalate, polybutylene terephthalate, polyester such as copolymer polybutylene terephthalate, or polyolefin such as polyethylene or polypropylene can be 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 a thinnable composite fiber of such a composite fiber 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, a weakly alkali-soluble polymer in the sea part, so that another polymer is arranged in the island part, or the other polymer is divided by the weakly alkali-soluble polymer, and both are joined to form a thin fiber. None, discharge from the discharge hole of the spinneret and take up at high speed to obtain undrawn yarn.

An important point of the present invention is how to draw the thus obtained undrawn yarn in a liquid bath without trouble. When this undrawn yarn is drawn all at once in a liquid bath having a temperature of higher than 65 ° C., the fibers stick to each other, resulting in poor card-passing properties and needle punching properties, resulting in fibers that cannot be put to practical use. Further, when stretched at 65 ° C. or lower, the crystallinity is not sufficiently improved and the fiber has poor physical properties. Therefore, finally, it becomes a problem how to stretch in a liquid bath at a high temperature while avoiding sticking without impairing the alkali solubility.

As a result of intensive studies by the present inventors in order to solve the above problems, the present invention has been achieved. The main point of the present invention is to carry out preliminary low-temperature primary drawing of the undrawn yarn according to the present invention and then carry out high-temperature liquid bath drawing. This low temperature primary stretching is performed in a liquid bath of 65 ° C or lower or 60 to 120 ° C.
The film is stretched under dry heat. For stretching in a liquid bath, it is necessary to keep the liquid temperature at 65 ° C or lower. If it exceeds 65 ° C, partial dissolution of the soluble component is observed, which causes a problem. If the temperature is too low, the stretchability will be a problem, so 3 is a guideline.
0 ° C or higher is preferable. Although some of the dissolved components themselves are partially dissolved even at 30 to 40 ° C., they are usually stretched at a temperature higher than this. However, the hot water resistance is simultaneously improved by the pre-crystallization or the molecular orientation during the drawing, and the liquid temperature of the pre-drawing can be sufficiently endured.
In the case of dry heat, if the stretching temperature is less than 60 ° C, the stretchability is poor, and if it exceeds 120 ° C, the fibers are likely to melt and melt. Therefore, stretching is performed at an appropriate temperature within the range of 60 to 120 ° C. Is. By this stretching, the same effect as the liquid bath stretching can be obtained. However, in the case of dry heat drawing, a hot plate, hot roll, heated air or the like can be used as a heating means for the fiber, but when the tow is thick like staple drawing, liquid bath drawing is performed from the viewpoint of eliminating uneven heat transfer. Is more preferable. Further, in the case of the liquid bath stretching, the glass transition temperature of the soluble component is lowered by coming into contact with the liquid, and it becomes possible to stretch at a surprisingly low temperature. In the present invention, by the primary stretching, the hot water resistance of the soluble component is increased, and then the ordinary high temperature liquid bath stretching of 65 ° C. or higher is performed. The primary draw ratio is 1.2
-3 times is preferable. At a magnification lower than 1.2 times, the orientation does not proceed sufficiently and the soluble component tends to be partially eluted.
On the other hand, if it exceeds 3 times, the fibers tend to be stretched at low temperature and have poor physical properties. After that, it is preferable to perform stretching 1.2 times or more at a high temperature. Although it depends on the physical properties of the undrawn yarn, it is preferable to draw it 1.2 to 5 times in order to sufficiently orient it at a high temperature to improve the physical properties of the fiber. By this stretching,
The original fiber structure is formed and stabilized, and the desired staple stretching is possible without the fibers sticking.

The thus obtained thinnable composite fiber of the present invention can be used as it is, or can be used in a wide variety of applications such as woven and knitted fabrics with other fibers, artificial leather with a non-woven fabric and a non-woven polyurethane. Is possible.

A fiber using this composite fiber is obtained by forming a cloth mainly and then subjecting it to a dissolution treatment with a weak alkali to obtain an ultrafine fiber. It is possible to continuously perform this dissolution treatment by providing a special treatment tank, but a normal high-order processing step,
That is, it is possible to carry out dissolution treatment using a dyeing method such as wince or circular, including the step of desizing and refining. 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 made of a polyester which is attacked by a strong alkali, the ultrafine fibers can be finely divided without adversely affecting them. 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.

[0024]

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

[Examples 1 to 3 and Comparative Examples 1 to 5] 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 an ultrafine fiber. Homopolyethylene terephthalate was used as the other polymer component after drying under reduced pressure.

Both components are 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 the sea component and the homopolyethylene terephthalate was the island component, and the composition ratio was 50% sea component and 50% island component.

The undrawn yarn thus obtained was subjected to a first stage liquid bath temperature of 55 ° C.
Was stretched at a draw ratio of 1.5 times and then continuously stretched at a second stage liquid bath temperature of 80 ° C. and a draw ratio of 2.0 times.

No yarn breakage during winding, winding around a roll, and deposits on guides were generated. The obtained drawn yarn had no stickiness on the fiber surface, and there was no sticking between single yarns observed by a microscope. In addition, the physical properties of the drawn yarn were good.

This drawn yarn was knitted into a cylinder. There was no yarn breakage or lint during knitting, and the knitted fabric was good.

This knitted fabric is treated with sodium hydroxide (NaOH)
Treatment with a 0.9% alkaline solution at 90 ° C. for 10 minutes was performed. Then, it was thoroughly washed with hot water and dried. The change in weight due to this treatment was 50% less than before treatment. In addition, when the cross section of the fiber was observed, it was found that each fiber was an ultrafine yarn of 0.05 denier and had a good feel to the touch.

In accordance with Example 1, composite fibers having the composition of the weakly alkali-soluble polymer shown in Table 1 were obtained, subjected to drawing examination and alkali treatment, and the results shown in Table 1 were obtained.

[0032]

[Table 1] (SI (mol%): 5-sodium sulfoisophthalic acid IPA (mol%): isophthalic acid State evaluation of drawn yarn: ○ Good (no problem) △ Slightly slimy fiber surface × Intergranular fiber adhesion Knitted fabric state evaluation: ○ Good (no problem) △ Slightly bad × Poor (fluffing, yarn breakage) Ultra-thinning by alkali treatment: ○ Good (no problem) △ Slightly bad × Ultra-thinning difficult) [Example 4] Same as Example 1 Align the unstretched yarns 1
A tow of 10,000 denier was obtained, and drawing was performed under the same two-stage drawing conditions of the liquid bath as in Example 1, and staples were obtained through crimping and cutting. The stretchability was good, and there was no problem in the process passability. The stretched tow had no slimy feel on the fiber surface and no sticking between fibers.

The obtained staples were passed through a card, a cross wrapper and a pre-punch machine (M / C), and then needle punched using a needle board to obtain an entangled sheet. The card passing property was good, and a web having no problem was obtained, and the punch entanglement property was not problematic at all.

Next, this sheet was treated with an alkali solution of sodium hydroxide (NaOH) 0.9% at 90 ° C. for 20 minutes. Then, it was thoroughly washed with hot water and dried.

The obtained sheet was an ultrafine fiber which was uniform even inside.

[Example 5] The same undrawn yarns as in Example 1 were gathered, denier of 30,000, and three heating rolls were used. The temperature of each roll was 65 ° C for the first stage, the second stage and the third stage. The stage is set to 95 ° C., and the first and second stages are 1.
After stretching 8 times, it was further stretched 2 times at a liquid bath temperature of 90 ° C. There was no yarn breakage during fiber drawing and no sticking between fibers, indicating a good drawn state.

A crimp was applied to this fiber, and a staple cut into 51 mm was used. After forming a web using a random web bar, needle punching was performed to obtain a felt. No troubles in the process during this period were recognized. Add this felt to a solution of 0.8% sodium hydroxide at 90 ° C.
When it was divided, a sheet completely made of ultrafine fibers was obtained.

[Comparative Example 6] In accordance with Example 4, Comparative Example 1
The tow drawing was performed under the conditions of. Although the stretchability was good,
The stretched tow had a slimy feel on the fiber surface, and there was partial interfiber sticking. There was no problem in staple physical properties.

When the obtained staples were passed through a card and a cross wrapper, an undisentangled portion of shell-shaped fibers and a nep were formed on the card, and a clean web could not be obtained.

[0040]

EFFECTS OF THE INVENTION According to the present invention, when a composite fiber containing a weakly alkali-soluble component is drawn in a liquid bath, the composite fiber which is difficult to draw in the liquid bath as it is is not degraded in its weak alkali solubility. It enables high temperature liquid bath stretching. As a result, good staple drawing becomes possible, and a composite fiber that can easily and stably obtain an ultrafine fiber can be obtained.

Claims (2)

[Claims] 1. A main constituent component of terephthalic acid and ethylene glycol, 6 to 12 mol% of 5-sodium sulfoisophthalic acid and 0 to 10 mo of the total acid component.
When drawing a dilutable composite fiber containing a weakly alkali-soluble polymer composed of a copolyester containing 1% of isophthalic acid as a component, in a liquid bath, a liquid bath of less than 65 ° C. or a dry heat of 60 to 120 ° C. After the first stretching at 65,
A method for producing a thinnable composite fiber, which comprises drawing in a liquid bath at a temperature of not less than ° C. 2. The first stretching is performed at a stretching ratio of 1.2 to 3 times, and then the stretching at a stretching ratio of 1.2 times or more is performed in a liquid bath at 65 ° C. or more. The method for producing a thinnable composite fiber.