JPH05331758A - Production of ultrafine fiber - Google Patents

Abstract

PURPOSE:To provide a splittable fiber capable of smoothly passing through treating processes before splitting and easily splittable to form ultrafine fibers by splitting treatment. CONSTITUTION:A component of a splittable conjugate fiber is composed of an ethylene terephthalate-type polyester and the other component contains 3-50wt.% of a polyalkylene glycol. The conjugate fiber can be split into individual components by applying a mechanical stress in the presence of water. Since a polyalkylene glycol is compounded to a component of the fiber, a strain is generated on the bonding face of the components by the absorption of water and the swelling with water to facilitate the splitting of the fiber by the application of mechanical stress.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing ultrafine fibers. More specifically, the present invention relates to a production method for stably obtaining ultrafine fibers by mechanically treating a polyester splittable conjugate fiber.

[0002]

2. Description of the Related Art Generally, non-woven fabrics using fine fibers
It is well known that the fabric has a soft texture,
Many proposals have been made as methods for obtaining such ultrafine fibers. The most useful method is 2 with different solubility.
There is a method in which sea-island fibers are formed from at least one kind of polymer, and sea components are dissolved and removed to obtain ultrafine fibers. However, in such a method, a solvent treatment step and a solvent recovery step are required, and there are drawbacks that the process becomes complicated and the cost is disadvantageous.

As another method, a composite fiber composed of polymers having no affinity for each other, for example, polyester / polyamide, polyester / polyolefin, polyamide / polyolefin, etc., is subjected to mechanical shock such as puffing, needle punching, high-pressure water treatment and the like. A method of forming ultrafine fibers by the method described above is proposed in JP-A-62-133164.

However, since the composite fiber obtained by such a method has a poor affinity between polymers, there is a problem that component cracking occurs when passing through the card process to form a web, resulting in a marked decrease in productivity. .. Furthermore, although polyamide or polyolefin is usually used as one component, these are inferior in light resistance / weather resistance, and the resulting ultrafine fibers are composed of two kinds of polymers, which complicates the dyeing process and also makes use of products such as nonwoven fabrics. There is a problem of being limited.

Another method is Japanese Patent Publication No. 61-1975.
No. 6 discloses that one component of a composite fiber is mixed with polyalkylene glycol, a high-pressure water stream is applied to a fiber product made of the composite fiber to crush and remove the component containing the polyalkylene glycol, and the other component is fibril. There has been proposed a method of forming (grouping ultrafine fibers). However, in such a method, the crushed polymer cannot be an effective fiber of the final product and is removed, which is disadvantageous in cost.
Further, there is a problem that the crushed polymer is not completely removed from the product and the quality is degraded.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to obtain good card passing property and to be easily divided by mechanical stress. It is an object of the present invention to provide a novel method for producing ultrafine fibers, which has excellent light resistance and weather resistance, is easy to dye, and has good quality.

[0007]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that both components of the composite fiber are made of polyethylene terephthalate polyester, and one component contains polyalkylene glycol. The present invention has found that the type composite fiber has sufficient adhesiveness when passing through the card process, while its adhesiveness is remarkably reduced in the presence of water so that both components can be easily separated and separated.

That is, according to the present invention, each component of the splittable conjugate fiber is composed of a polyester whose main repeating unit is ethylene terephthalate, and one component is 3 to 50% by weight of polyalkylene glycol (based on the polyester). The present invention provides a method for producing an ultrafine fiber, characterized in that the contained splittable conjugate fiber is divided into respective components by applying a mechanical stress in the presence of water.

The splittable conjugate fiber used in the present invention is
One component is divided into a large number by the other component, and the divided other component is not particularly limited as long as it has a fiber cross-sectional shape which is not buried in the one component. 29636, Japanese Patent Laid-Open No. Sho 50
It can be easily obtained by the method disclosed in JP-A-5650. Specific cross-sectional shapes include, for example, those shown in FIGS. 1 (a) to 1 (e). Among them, those having a hollow in FIG. 1 (a) are divided by mechanical stress effectively acting. This is preferable because it is easy to do so, and the water penetration into the fiber is good and the splittability is further improved.

Both components constituting such a splittable conjugate fiber must be polyesters whose main repeating unit is ethylene terephthalate from the viewpoints of light resistance and weather resistance of the ultrafine fibers to be finally obtained. The polyesters may be the same or different. The term "mainly" as used herein means that 80 mol% or more is composed of ethylene terephthalate units, and other components are 20%.
It may be a polyester copolymerized by not more than mol%.
As the copolymerization component preferably used, acid components such as isophthalic acid, phthalic acid, 5-sodium sulfoisophthalic acid, naphthalene dicarboxylic acid and 4,4'-diphenyldicarboxylic acid, trimethylene glycol, tetramethylene glycol, diethylene glycol, neo Examples thereof include diol components such as pentyl glycol.
Among them, if the polyester copolymerized with isophthalic acid, neopentyl glycol, etc. is used as only one component, the difference in hot water shrinkage between the two components constituting the composite fiber becomes large,
It is preferable because division by mechanical stress becomes easy.

Next, in the present invention, a polyalkylene glycol is added to one component of the above-mentioned polyester composite fiber, and 3 to 5 relative to the polyester constituting the component.
It is important to contain 0% by weight, preferably 10 to 50% by weight. When the content of the polyalkylene glycol is less than 3% by weight, it is considered that the adhesive force between the two components of the composite fiber is increased, and even if the treatment described below is applied, it becomes difficult to peel and divide to obtain ultrafine fibers. I will not be able to. On the other hand, when it exceeds 50% by weight, not only the melt viscosity of the component is greatly reduced and stable spinning cannot be performed, but also
When the toughness of the component decreases and the treatment described below is performed,
This is not preferable because the component easily breaks into powder. In addition, the light resistance is also reduced.

It is desirable that the polyester of the other component is substantially not blended with polyalkylene glycol, but it may be contained in a small amount as long as it does not impair the object of the present invention.

Polyalkylene glycols preferably used include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, ethylene oxide / propylene oxide block or random copolymers, and these are alkyl groups, aryl groups, The terminal may be blocked with an acyl group or the like, and may be a block polyether ester or a block polyether amide obtained by reacting various glycol components or amine components and acid components. Among them, the one in which the end is blocked with an alkyl group is more preferable because it has good light resistance.

As these polyalkylene glycols, those having an average molecular weight of 5,000 to 600,000 can be used, but 5,000 to 100,000, particularly 50.
It is more preferably from 00 to 50,000 from the viewpoint of availability. 5
If it is 0000 or more, it is difficult to carry out the polymerization by an inexpensive method and the cost becomes high.

Next, the method of incorporating the above-mentioned polyalkylene glycols into polyester includes a method of adding during the polymerization of polyester, and a method of melt kneading after mixing polyester chips and polyalkylene glycols during melt spinning of the composite fiber. Any method such as a method in which separately melted polyester and polyalkylene glycols are kneaded before melt spinning can be adopted, but in general, polyalkylene glycols have poor heat resistance, and melt spinning work is From the standpoint of ease and the like, it is desirable that the polyester chips and the polyacetylene glycols be mixed and then melt spun.

In the splittable conjugate fiber of the present invention described above, it is desirable that the difference in thermal shrinkage between the components when treated in boiling water for 20 minutes is 2% or more, preferably 5% or more.
Such a composite fiber causes interfacial strain in the component based on the difference in shrinkage between the components when the treatment condition described below is set to a high temperature,
It becomes easy to peel and divide due to mechanical stress. Further, even in a portion where peeling and splitting due to mechanical stress does not occur, peeling and splitting progresses during dry heat treatment, and an ultrafine product of good quality can be obtained.

In the present invention, the above-mentioned composite fiber is
It is important to apply mechanical stress in the presence of water. When water is not substantially present, exfoliation and splitting between components is difficult to proceed even when mechanical stress is applied, and extremely large stress must be applied to achieve sufficient splitting. This is not preferable because the quality of the product is degraded. The higher the temperature of water is, the easier the separation by peeling due to stress is, which is more preferable.

The method of allowing water to be present is not particularly limited, and water may be adsorbed to the ultrafine fibers in advance before mechanical stress is applied, for example, by immersing in water, or at the same time when stress is applied. Water may be added. Specifically, for example, a card method from short fibers, a cross wrapper method, a random weber method or a method of needle punching after immersing a nonwoven fabric prepared by a nonwoven fabric forming method such as a spun bond method from long fiber filaments in water, Examples of the method include a method of water-needing a non-woven fabric with a high-pressure water stream without immersing it in water, and a method of dyeing and puffing after forming a fabric.

The composite fiber used in the present invention preferably has a fineness of the obtained ultrafine fiber of 0.5 to 20 denier within a range of 0.8 denier or less, and is subjected to mechanical stress. In the stage before the separation and division, especially in the stage of the yarn making, it is desirable that moisture is not applied as much as possible, and when it is necessary to immerse in water, it is desirable to shorten the time as much as possible and dry it quickly.

[0020]

The splittable conjugate fiber which is the object of the present invention uses polyethylene terephthalate polyester in which one component contains 3 to 50% by weight of polyalkylene glycol. Due to water absorption and swelling, distortion occurs on the joint surface with the polyethylene terephthalate-based polyester in which the other component polyalkylene glycol is not substantially blended, and as a result, the interface is easily peeled off due to the load of mechanical stress. Each component of the composite fiber becomes an ultrafine fiber. This is shown in FIG.
It is also supported by the photograph of the fiber morphology after the split peeling attached to.

The ultrafine fibers obtained by the present invention are:
Since all the components are made of polyethylene terephthalate polyester unlike the conventional ones, they are characterized by easy dyeing, excellent light resistance and weather resistance, and good heat resistance. Moreover, the composite fiber according to the present invention has a good process-passing property even in the process where substantially no water is adhered, such as a card process and a non-woven fabric manufacturing process, in which component cracking hardly occurs even when mechanical stress is applied. It also has the characteristic that it has an extremely high industrial value.

[0022]

The present invention will be described in more detail with reference to the following examples. The difference in shrinkage rate of boiling water was measured according to the following method. Difference in shrinkage rate of boiling water After immersing a web made of composite short fibers and having a basis weight of 20 g / m ² in boiling water for 20 minutes, pressure 1 was applied from a jet nozzle in which holes with a diameter of 0.1 mm were arranged in a row at a pitch of 0.6 mm.
A columnar water stream was sprayed at 20 kg / cm ² , and the shrinkage ratio difference was obtained from the fiber length distribution of the separated fibers.

[0023]

Example 1 Polyethylene terephthalate (intrinsic viscosity 0.63) and polyethylene glycol (molecular weight 20000) were used as one component A of the splittable conjugate fiber in a weight ratio of 100.
/ 11. 1 mixed with polyethylene terephthalate (intrinsic viscosity 0.63) as the other component B, each of which was melted in a vacuum suction ruder to give a weight ratio of 1
An undrawn yarn was obtained by spinning a composite fiber having a cross-sectional shape shown in FIG. 1 (a) at a speed of 1/1 and taking it up at a speed of 1000 m / min.

The undrawn yarns are drawn together and drawn at a drawing temperature of 80 ° C.
Stretching to 3.0 times with, and applying crimp after applying oil agent,
Then, relaxation heat treatment was performed at 90 ° C. for 20 minutes to obtain short fibers having a single yarn fineness of 2 denier and a fiber length of 51 mm.

The short fibers obtained were passed through a spinning and weaving process, dyed at 130 ° C. and subsequently subjected to puffing.
As a result, the above-mentioned process passability was good, and when the obtained cloth was observed with a microscope, about 98% of the fibers (ultrafine fiber-forming components) were separated and separated, and the texture of the cloth was extremely good. ..

[0026]

Comparative Example 1 On the other hand, the same procedure as in Example 1 was carried out except that nylon 6 (intrinsic viscosity 1.34) was used as the component A. As a result, component cracking occurred in the spinning and weaving processes, and a stable fabric was obtained. Was difficult.

[0027]

Comparative Example 2 On the other hand, the same procedure as in Example 1 was carried out except that as the component A, a polyethylene glycol compounding amount of 2% by weight was used. As a result, although the passability in the spinning and weaving processes was good, the division into ultrafine fibers hardly proceeded, and the obtained fabric had a hard texture.

[0028]

Example 2 On the other hand, as the component B, 10 parts of an isophthalic acid component were used.
Mol% (based on all acid components) Copolymerized intrinsic viscosity 0.6
A composite fiber was obtained in the same manner as in Example 1 except that the polyethylene terephthalate yarn polyester of 4 was used.

The obtained staple fibers were put into a roller card (60
m / min) to make a web with a basis weight of 20 g / m ² .
Then, a process of spraying a columnar water stream at a pressure of 120 kg / cm ² from a group of jet nozzles in which holes having a diameter of 0.1 mm are arranged in a row at a pitch of 0.6 mm is repeated three times to entangle, and then at 160 ° C. for 20 minutes. It was dried with hot air.

When the obtained sheet was observed with a microscope, about 95% of the fibers were separated and separated.

The difference in boiling water shrinkage between the two components of the composite fiber was 5.1% when the fiber length of the A component was 50.6 mm and that of the B component was 48 mm.

[0032]

Comparative Example 3 Example 2 except that polyethylene terephthalate having an intrinsic viscosity of 0.63 alone is used as the component A
It carried out similarly to. As a result, although the card passing property was good, almost no division into ultrafine fibers was observed, and the obtained sheet had a poor texture.

[0033]

Example 3 The same procedure as in Example 2 was carried out except that polyethylene glycol was used as the component A in an amount of 5% by weight. When the obtained sheet was observed with a microscope, about 90% of the fibers were separated and separated.

The difference in shrinkage of boiling water between the two components of the composite fiber is A
Fiber length of component is 50.8mm B component is 48mm
Was 5.5%.

[0035]

Example 4 Example 4 was repeated except that polyethylene glycol was used as the component A in an amount of 45% by weight. When the obtained sheet was observed with a microscope, about 97% of the fibers were separated and separated.

The difference in shrinkage rate of boiling water between the two components of the composite fiber is A
The fiber length of the component was 50.9 mm, and that of the B component was 48 mm, which was 5.7%.

[Brief description of drawings]

1A to 1E are cross-sectional shapes showing an example of a splittable conjugate fiber used in the present invention.

FIG. 2 is a scanning electron micrograph (× 2000) showing the division of the conjugate fiber obtained in Example 2 into ultrafine fibers.

[Explanation of symbols]

 1 component of splittable conjugate fiber 2 other component of splittable conjugate fiber 3 hollow part

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location D01F 8/14 D 7199-3B D03D 15/00 F 7199-3B D04H 1/46 A 7199-3B D06C 11/00 Z D06M 11/05 11/84 (72) Inventor Masahiko Ikeda 77 Kitayoshidacho, Matsuyama City, Ehime Prefecture Teijin Limited Matsuyama Office

Claims (2)

[Claims] 1. A split-type composite fiber in which each component of the split-type conjugate fiber comprises a polyester whose main repeating unit is ethylene terephthalate, and one component of which contains 3 to 50% by weight (based on polyester) of a polyalkylene glycol. A method for producing an ultrafine fiber, characterized in that the composite fiber is divided into respective components by applying a mechanical stress in the presence of water. 2. The method for producing ultrafine fibers according to claim 1, wherein the boiling water shrinkage ratios of both components constituting the splittable conjugate fiber differ by 2% or more.