JP3518133B2 - Method for producing short fiber having latent fibril properties - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to latent fibrillation .
More specifically, the present invention relates to a method for producing a staple fiber having a latent fibril characteristic in which the tip portion of the staple fiber is preferentially fibrillated by alkali reduction processing .
Regarding the manufacturing method .

[0002]

2. Description of the Related Art Synthetic fibers typified by polyester are very often used for clothing applications, and polyester short fibers are also frequently used as polyester spun yarn.
Fineness by direct spinning for the purpose of softening the texture,
Ultra-thinning is being actively carried out by the division technology. However, even with such fineness, it has not been possible to obtain a sufficiently soft texture.

Therefore, there has been proposed a technique for imparting a soft texture by fibrillating fibers.
For example, there is Japanese Patent Publication No. 2-58374. In this technique, the surface of the fabric is uniformly fibrillated regardless of the position of the fibers, so that the strength of the fabric as a whole is reduced if a sufficient fibrillation effect is to be exhibited. Further, Japanese Patent Publication No. 63-6671 is a technique for blending incompatible polymers to form fibrils, which tends to result in poor spinnability and fibrillation irrespective of the position of fibers, resulting in a decrease in fabric strength. There was a drawback to Further, in Japanese Patent Application Laid-Open No. 7-252738, there is a proposal for a raised yarn in which a part of the fiber is split into fibrils, but this raised yarn is also fibrillated regardless of the position of the fiber, and it is sufficient as in the above proposal. It has a drawback that the strength of the fiber is not sufficient to develop such a soft texture.

[0004]

The inventors of the present invention have made extensive studies in order to solve the above-mentioned drawbacks, that is, the inability to satisfy both the fabric strength and the sufficient softness due to fibrils, and as a result, the present invention has been reached. .

[0005]

The object of the present invention is to dissolve easily.
The solvent velocity ratio of the soluble polymer (A) and the easily soluble polymer is
Compatibility of 5 or more and higher melt viscosity than easily soluble polymers
After blending the base polymer (B) with
Melt residence time is 50 minutes or less, and the resulting fiber is
A feature that cuts to a length of 00 mm or less
This is achieved by the method for producing short fibers having brillability .

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The short fibers of the present invention are required to have a ratio of the number of fibrils at the tip portion to the number of fibrils at the non-tip portion of the short fiber at the time of weight reduction processing with a solvent of 1.3 or more. If the ratio is less than 1.3, the strength of the woven fabric or the like will be deteriorated when trying to develop a sufficient soft texture, and the purpose cannot be achieved. The preferable fibril number ratio is 2.0 or more, and more preferably 5.0 or more. Particularly preferably, it is 10.0 or more. The method for measuring the number of fibrils at the tip of the short fibers and the number of fibrils at the non-tip is as follows. For the fibril number at the tip, the short fibers are reduced by 10% with a solvent. Align the weight-reduced short fibers at right angles to the fiber axis, take an SEM photograph of the tip, and count the number of fibrils with a length of 2 μm or more. The number of repetitions is set to 5, and the average thereof is used. On the other hand, regarding the number of fibrils in the non-tip portion, an SEM photograph is taken by aligning the central portion in the length direction of the short fibers treated as described above at right angles to the fiber axis, and the number of fibrils is counted in the same manner as in the tip portion.

The absolute number of fibrils is also important, and the number of fibrils at the tip of the fiber must be 3 or more per tip. It is more preferably 8 or more, and particularly preferably 15 or more.

The solvent in the present invention is not particularly limited, but in the case of polyester fiber, an alkaline aqueous solution represented by caustic soda is used, and in the case of nylon fiber, formic acid is preferably used.

The short fiber of the present invention is preferably a hollow cross-section fiber having a hollow ratio of 5% or more. When the hollow cross-section fiber is used, it is possible to easily increase the ratio of the number of fibrils in the tip portion to the number of fibrils in the non-tip portion by progressing weight reduction processing from the outside and inside of the fiber. The higher the hollow rate, the more preferable it is, 10% or more, and more preferable, it is 18% or more. However, when the hollowness is more than 50%, the hollowness is preferably 50% or less because the fibers are easily crushed.

The polymer forming the short fibers is preferably polyester, and particularly preferably 85 mol% or more of the repeating unit is ethylene terephthalate. Further, it is preferable for the fibril formation that the repeating unit of the polymer constituting the fiber contains 0.5 mol% or more of 5-sodium sulfoisophthalate group.

Generally, the larger the number of fibrils in the fabric is, the softer the texture is, but it is difficult to simply increase the number of fibrils per fiber. Therefore, it is effective to limit the fiber length. The length of the short fiber of the present invention is 20
It is preferably 0 mm or less. When the length exceeds 200 mm, it is difficult to increase the number of fibrils,
It is difficult to make the texture soft enough. The preferred fiber length is 120 mm or less, particularly preferably 90 mm or less. There is no particular lower limit to the fiber length, but 30 is required when spinning.
mm or more is preferable. The fiber length is not limited to this, and can be preferably used in the range of 0.3 to 5 mm for non-spinning applications such as flock applications.

The latent fibrillar staple fiber of the present invention can be produced, for example, as follows. Homopolyethylene terephthalate (70% by weight) and a melt viscosity lower than that of the polyethylene terephthalate, polymerized with 5 mol% of 5-sodium sulfoisophthalate are polymer blended at the time of spinning. Discharge to obtain hollow undrawn yarn. The unstretched yarn is stretched in a liquid bath at 90 ° C. and then a fiber length of 76
mm staples are produced.

After the spinning, the obtained short fibers are used to obtain a woven fabric made of 100% polyester spun yarn in both warp and weft by using the spun yarn of the present invention. Then, by applying a 10% weight reduction process at 90 ° C. with a 3 wt% caustic soda solution, the fiber strength is increased while developing a large number of fibrils on the woven surface.
As a result, the physical properties of the fabric are not significantly impaired.

[0014]

The present invention will be described in more detail with reference to the following examples. The examples of the present invention were measured by the following methods.

A. Short fibril number short fibers in a 30 g / l caustic soda solution at a bath ratio of 1:10
0 and the weight reduction processing is performed under the condition that the weight reduction rate is 10% at 90 ° C. The tip of the weight-reduced fiber is aligned at right angles to the fiber axis and a SEM photograph of the tip is taken to count the number of fibrils having a length of 2 μm or more. The number of repetitions is set to 5, and the average thereof is used.

B. Number of fibrils in the non-tip portion The number of fibrils in the non-tip portion is the same as that of the tip portion, taken by taking an SEM photograph with the central portion of the length-reduced short fibers aligned at right angles to the fiber axis. Count the number of fibrils.

C. Intrinsic viscosity It was measured with orthochlorophenol at 25 ° C.

D. Softness 10 panelists evaluated the feel by touch, 8 or more samples were soft, 6-6 were soft samples, 4-5 were soft samples, and Δ3.
Samples that were softer than people were marked as x.

E. The cross-section of the hollow fiber raw cotton was photographed and expressed as the ratio of the cross-sectional area of the hollow part to the total cross-sectional area obtained from the outer shape.

Example 1 70% by weight of polyethylene terephthalate having an intrinsic viscosity of 0.78 as a base polymer (B) and an easily soluble polymer (A)
5-sodium sulfoisophthalate as 5.0 mol%
30% by weight of copolymerized polyethylene terephthalate having an intrinsic viscosity of 0.55 was chip-blended, discharged from a hollow spinneret consisting of 3 slits with a melt retention time of 18 minutes, and the undrawn yarn was wound up. This unstretched yarn is 3.8 times, 95 ° C
Liquid bath drawing and then relaxation heat treatment at 120 ° C. to obtain 2.5 denier fibers. This fiber was cut into a length of 51 mm. This raw cotton was used to make No. 30 spun yarn. Using the obtained spun yarn for warp and weft,
Both weft yarns were woven fabrics having a weaving density of 85 yarns / inch. The obtained woven fabric was treated with a 3% by weight aqueous solution of caustic soda and subjected to 10% weight reduction processing. This woven fabric was disassembled and the number of fibrils at the tip and non-tip of the short fiber was measured, and the results are shown in Table 1. The fabric had a sufficiently soft texture.

Examples 2 to 4 and Comparative Examples 1 to 2 Tests were conducted in the same manner as in Example 1 except that the ratio of the polymer to be blended was changed as shown in Table 1. In Example 2, the number of fibrils was reduced and the soft texture was slightly inferior to that in Example 1. The fibril number of Example 3 was smaller than that of Example 1 as in Example 2. In Example 4, although the object of the present invention was achieved, the soft feeling was obviously inferior. In Comparative Example 1, almost no formation of fibrils was observed. Also, in Comparative Example 2, almost no fibrils were observed as in Comparative Example 1.

Examples 5-6, Comparative Examples 3-4 The composition of the easily soluble polymer (A) was changed as shown in Table 1. In Examples 5 and 6, 3-sodium sulfoisophthalate component was used
The copolymerization was changed to mol% and 7 mol%. The other tests were performed in the same manner as in Example 1. In Example 5, the number of fibrils was found to be almost the same as in Example 1, but the fibril length was short. A woven fabric made of this fiber was slightly lacking in softness. In Example 6, the length of the fibril was increased, but the thickness of the fibril was thin and the texture of the fabric was Example 1.
It was a little rougher than. In Comparative Example 3, the amount of 5-sodium sulfoisophthalate component was 1.7 mol%. The obtained fibrils had a small number of fibrils and the fibrils had a very short length. The texture was coarse and hard. Comparative Example 4 is 5
-Sodium sulfoisophthalate component was 10 mol%. Not only the tip of the fiber but also the non-tip was fibrillated, and the fabric strength was low, which was not suitable for practical use.

Examples 7 to 9 and Comparative Example 5 The hollow ratio was changed as shown in Table 1. The test was performed in the same manner as in Example 1 except that the hollow ratio was changed. Although Example 7 was a raw cotton with a high hollow ratio, it was a good woven fabric with excellent softness. Example 8 was a raw cotton with a hollowness of 10%, but the number of fibrils was small, and the woven fabric was slightly inferior in softness to Example 1. Example 9 has a hollowness of 5
%, But because the number of fibrils is slightly insufficient, Example 1
There was a feeling of coarseness and hardness compared to. Comparative Example 5 was tested in the same manner as in Example 1 except that the intrinsic viscosity of the polymer (C) was changed. The small number of fibrils and the low tensile strength of raw cotton made it unsuitable for practical use. Also,
The hollow ratio was low and the feeling of coarseness and hardness was strong.

Example 10 A test was conducted in the same manner as in Example 1 except that the hollow spinneret was not used at the time of spinning and a simple circular hole was used for discharging to form a circular solid cross section. Although the number of fibrils was slightly insufficient and the soft texture was somewhat insufficient, it had high strength and was difficult to be crushed, and was highly practical.

[0025]

[Table 1]

[0026]

INDUSTRIAL APPLICABILITY The fiber of the present invention is a latent fibril staple fiber in which many fibrils are expressed in the tip portion and only a small amount of fibrils are expressed in the non-tip portion. Therefore, by reducing the weight of the woven fabric made of the short fibers, the woven fabric can be soft-touched and at the same time have excellent physical properties as a fabric.

[Brief description of drawings]

FIG. 1 is a schematic view of a tip portion and a non-tip portion of a fiber obtained by alkali-reducing a short fiber.

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-2-6648 (JP, A) JP-A-62-289642 (JP, A) JP-A-7-102439 (JP, A) JP-A-55- 16906 (JP, A) JP 56-118962 (JP, A) JP 6-41836 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) D06M 11/00 D06M 11 / 38 D01D 5/24 D01F 6/92

Claims (2)

(57) [Claims] 1. A blend of an easily soluble polymer (A) and a base polymer (B) having a solvent rate ratio of 5 or more to the easily soluble polymer and having a melt viscosity higher than that of the easily soluble polymer. A method for producing short fibers having fibrillation, characterized in that the subsequent melt retention time is discharged for 50 minutes or less, and the obtained fibers are cut into a length of 200 mm or less. Wherein ejecting polymer after blending the hollow die, a manufacturing method of the short fibers having fibril of claim 1, wherein the hollow ratio is 5% or more of the hollow fibers.