JPH07300767A - Production of ultra-fine fiber - Google Patents

Abstract

PURPOSE:To obtain ultra-fine fibers without any remaining unsplit fibers by pressurizing splittable type conjugate fibers before dissolving a polymer constituting the conjugate fibers. CONSTITUTION:This method for producing ultra-fine fibers is to pressurize conjugate fibers, preferably peelable and splittable type conjugate fibers comprising a polyester containing a polyoxyethylene-based polyether and a polyester containing ethylene terephthalate unit as a main recurring unit at a temperature of the second order transition point of the polymer or below with a calender roll (under 5-60kg/cm linear pressure) before dissolving a readily soluble polymer in the fibers. The resultant polyester-based ultra-fine fibers have a high dissolution rate and are capable of readily and completely dissolving the readily soluble polymer without any remaining unsplit part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing ultrafine polyester fibers in which undivided fibers do not remain.

[0002]

2. Description of the Related Art The use of synthetic fibers is expanding due to their excellent properties, and in particular, fabrics made of ultrafine fibers having a single fiber fineness of 0.1 denier or less have come to be used for various purposes.

[0003] Conventionally, as a method for producing a fabric made of ultrafine fibers, for example, Japanese Patent Publication No. Sho 60-7723 discloses a method for producing ultrafine fiber fabric by dissolving and removing sea components of sea-island type composite fibers. Japanese Patent Publication No. 55-116874 discloses that
There is disclosed a method (hereinafter referred to as "warming") for obtaining an ultrafine fiber cloth by accelerating interfacial peeling by reducing the amount of alkali of a cloth composed of a peelable split type composite fiber composed of polyethylene terephthalate and nylon 6.

However, in these methods,
Since it is difficult to divide all the fibers that make up the fabric, undivided fibers tend to remain, and there are drawbacks such as uneven dyeing between the undivided portion and the divided portion, which causes dyeing spots. Was.

On the other hand, if an attempt is made to increase the alkali weight loss rate so as to prevent the undivided fibers from remaining, there is a problem that the physical properties of the fibers may be deteriorated and the fibers may not be practically used.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems of the prior art and to provide a method for producing ultrafine fibers in which no undivided fibers remain.

[0007]

DISCLOSURE OF THE INVENTION As a result of intensive studies conducted by the present inventors to achieve the above object, a peelable split type composite formed from at least two kinds of fiber-forming polymers having different solubilities. Before the fibers and / or the sea-island type composite fibers are melt-blended, when the fibers are pressed, preferably at a temperature below the second-order transition point of the fibers, it is very easy to melt the pressed part. Investigated.

Thus, according to the present invention, the easily-dissolvable polymer in the peelable split-type composite fiber and / or sea-island type composite fiber formed from at least two kinds of fiber-forming polymers having different solubilities is dissolved. A method for producing ultrafine fibers, characterized in that, when the ultrafine fibers are produced by pressurizing the conjugate fiber before the polymer is melted, is provided.

As shown in FIG. 1, the split-split type conjugate fiber and / or the sea-island type conjugate fiber used in the present invention has a fiber cross-sectional shape in which one component A is divided into a plurality of other components B. The composite fiber that is included and / or the composite fiber that includes the sea component C and the island component D as shown in FIG.

The form of the composite fiber may be appropriately set according to the desired single fiber shape and the single fiber fineness.

Further, the component A in the splittable splittable conjugate fiber
The combination of and B, or the combination of the components C and D in the sea-island type composite fiber may be appropriately set according to the conditions of melt splitting, and examples thereof include polyester, polyamide, polyethylene or polystyrene.

Further, a modified polymer obtained by copolymerizing or blending the third component with the above polymer, an antioxidant, an ultraviolet absorber, a heat stabilizer, a flame retardant, an optical brightening agent, titanium oxide,
It may be a polymer blended with an optional additive such as a colorant and inert fine particles.

Of these, peelable splittable conjugate fibers are preferably exemplified by using a polyester containing a polyoxyethylene type polyether as the component A and using a polyester having an ethylene terephthalate unit as a main repeating unit as the component B.

The shape of the composite fibers may be filaments, woolly textured yarns, spun yarns, synthetic fibers other than polyester fibers, natural fibers such as cotton and wool, recycled fibers such as rayon, and polyethylene terephthalate, if necessary. It may be used in the form of interwoven, interwoven, interwoven, mixed fiber or the like with a block copolymerized polyetherester elastic fiber in which the base polyester is a hard segment and the polyoxybutylene glycol polyester is a soft segment.

Next, the above-mentioned composite fiber is pressed in a yarn state before and after drawing after spinning, or is knitted or woven into an arbitrary structure and pressed in a fabric state, and then the fiber is obtained. When it is dissolved and treated with a solvent of any of the polymers constituting the above, it is extremely easily melted mainly in the fiber axis direction to form ultrafine fibers.

Here, the ultrafine fibers have a single fiber fineness of 0.1.
It is less than denier.

The single fiber fineness of the ultrafine fibers obtained by the method of the present invention is about 0.001 denier, although it varies depending on the single fiber fineness and shape of the fiber before the splitting, the conditions of pressure or splitting. It has been confirmed that even things can be obtained.

The pressurization needs to be carried out before the dissolution treatment, but it may be carried out before or after any step of greige, refining, presetting, washer or high temperature wet heat treatment (relaxation).

As a preferable pressing method, cotton,
Calendering using a roll made of metal or the like can be mentioned. When a so-called friction roll having different upper and lower roll speeds is used, a particularly remarkable melting effect is exhibited at the time of alkali reduction.

Depending on the purpose, a roll having a flat surface or an embossed roll engraved with a pattern can be used.
It is selected appropriately.

The pressing temperature is preferably a temperature below the second-order transition point of the above composite fiber. The secondary transition point is a value measured by DSC, and when a plurality of secondary transition points are observed for each polymer component constituting the composite fiber, the average value thereof is used as the secondary transition point. And

When the pressing temperature exceeds the second-order transition point,
Deformation of the composite fiber occurs, which is not preferable.

The pressure at this time is 5 to 60 in linear pressure.
Kg / cm is preferred.

If the linear pressure is less than 5 kg / cm, the fibers may not be sufficiently cleaved even if the cleaving treatment is carried out. On the other hand, if the linear pressure exceeds 60 kg / cm, the fibers are flattened and have a gloss. It may increase and cannot be put to practical use.

Examples of the pressurizing method other than calendering include stonewashing. In these methods, the fibers constituting the cloth are partially and randomly pressed by solids such as stones.

The type of solvent used in the dissolution treatment after pressurization and the treatment conditions may be appropriately selected according to the constituent components of the conjugate fiber. For example, in the case of splittable conjugate fibers containing polyester as a constituent component, Dissolution occurs in a low-concentration alkaline aqueous solution.

The alkaline aqueous solution used at this time is exemplified by an aqueous solution of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and the like. In this aqueous solution, a quaternary ammonium salt which is a weight loss promoter or a cloth of an alkaline solution is used. The amount of alkali may be reduced by adding a surfactant or the like that promotes the penetration into water.

Specific examples of the quaternary ammonium include tetramethylammonium chloride and the like, and specific examples of the surfactant include an alkyl phosphate type surfactant (Neolate NA-30, manufactured by Nika Kagaku).

The concentration and temperature of the alkaline aqueous solution depend on the kind of the alkaline compound used, but the concentration is 10
~ 300 g / l, temperature 40 ~ 180 ° C, treatment time 2
The range of minutes to 20 hours is preferred. In this case, the preferable alkali weight loss rate range is 5 to 40%.

In the present invention, when the pressure is uniformly applied to the entire surface of the cloth by using, for example, a calender roll, all the composite fibers constituting the cloth are melted and cracked. A homogeneous ultrafine fiber fabric is obtained in which no undivided fibers remain.

Further, it is of course possible to make a fabric in which divided fibers and undivided fibers are mixed by appropriately adjusting the pressurizing conditions.

On the other hand, when pressure is applied to only a part of the cloth by using an embossing roll or the like, the fibers constituting the pressed part are preferentially thinned by the melting treatment, so that the unpressed It is also possible to impart a pattern of embossing roll to the cloth by changing the apparent dyeing property and gloss in comparison with the area (usually, the ultrafine area appears to be lightly dyed).

Even when a pattern is drawn on the cloth with a pencil or the like, if the pressure applied is sufficiently high, only the fibers in the pressed portion are preferentially made fine by the alkali weight reduction,
Any pattern can be applied.

Further, if the amount of alkali is reduced after the stone wash process or the like, a random pattern can be imparted to the cloth.

Further, according to the present invention, since an ultrafine fiber cloth having no undivided fibers remaining can be obtained, the reflection of the main light on the surface of the cloth is changed from specular reflection to diffuse reflection, which has never been obtained before. The fabric has a whiteness.

[0036]

In the present invention, the composite fibers are very easily melted by applying pressure before the splitting treatment, so that there is no undivided fiber remaining when the entire surface of the fabric is pressed. A homogeneous ultrafine fiber cloth is obtained.

Further, when pressure is applied to an arbitrary portion of the cloth, the fibers constituting the pressed portion are preferentially made ultrafine, so that an arbitrary pattern can be imparted to the ultrafine fiber cloth. .

Although the mechanism of manifestation of such a phenomenon has not been sufficiently clarified, a crack is formed at the bonding interface of the polymer constituting the composite fiber by applying pressure, and the polymer is dissolved in the solvent of the polymer. At times, it is estimated that the weight loss preferentially progresses from the cracks and the composite fibers are easily cracked to become ultrafine fibers.

By the way, in the present invention, it has been confirmed that the weight loss rate of the composite fiber is several times faster than that in the case where no pressure is applied.

[0040]

EXAMPLES The present invention will be specifically described below with reference to examples. The evaluation method used in the examples was according to the following method. (1) Luminous density L * value Macbeth 2020+ (manufactured by Colmogen USA)
With D65 light source and 10 degree field of view
Lightness index L of the UCS color system according to 8730-1980
* The value was calculated. The smaller the L * value, the deeper the color is dyed, and the higher the visual density is. (2) Whiteness (L * -b * value) A cloth (undyed cloth) having a reduced weight was measured in the same manner as the above-mentioned luminous density, and the L * value and the chromaticity index b * value were calculated. The larger the L * -b * value, the larger the whiteness.

[0041]

Example 1 A side-by-side type conjugate filament of 85 denier / 24 filament, which was a composite of polyethylene terephthalate having an intrinsic viscosity of 0.45 and polybutylene terephthalate having an intrinsic viscosity of 0.85 at a ratio of 40:60. Obtained.

On the other hand, as the component A, a dicarboxylic acid component and ethylene glycol are transesterified, and then three alkyl groups each having an average carbon number of 21 are bonded to both ends of the polyoxyethylene chain. Water-insoluble polyoxyethylene-based polyether was added to the polyester matrix in an amount of 3% by weight, and then polyester polymerized by a conventional method was used. As component B, polyethylene terephthalate having an intrinsic viscosity of 0.64 was used. , A split type solid conjugate fiber having a shape shown in FIG. 1 (however, A and B are 32 layers, 180 denier / 4 respectively)
0 filaments) was obtained.

Here, "water-insoluble" means 100 g of pure water.
When 5 g of the polyoxyethylene-based polyether is put in it, heated at 100 ° C. for 60 minutes, cooled to room temperature, and naturally filtered with JIS standard 5 A filter paper, 90% or more is filtered out. .

Next, the above conjugate filaments and splittable conjugate fibers were gathered and supplied to an interlace nozzle, and the overfeed rate was 2.5% and the pneumatic pressure was 2.8K.
After the fibers were mixed at g / cm, the false twisting speed was 350 m / min, the surface speed of the false twisting disk was 650 m / min, the false twisting temperature was 135 ° C., and the simultaneous drawing false twisting was performed at a draw ratio of 2.0 times.

The obtained textured yarn had a two-layer structure in which the conjugate filament was arranged in the core part and the composite fiber was arranged in the sheath part.

Then, the plain weave was woven using the yarns as the warp and weft, and then scouring, relaxing, drying and preset were carried out by a conventional method.

Then, the above woven fabric was made into a cloth by using a calendering machine having a mirror surface roll and a paper roll.
Immediately after immersing in ice water at ℃, temperature 10 ℃, linear pressure 30Kg
/ Cm, and the pressure treatment was performed under the conditions of a speed of 10 m / min.

The obtained woven fabric was boiled in an aqueous sodium hydroxide solution having a concentration of 20 g / l for 45 minutes to reduce the weight by 40%. The whiteness of the obtained woven fabric was 104.

Subsequently, the dye bath shown in Table 1 was used at 130 ° C. for 60 minutes.
Stained for minutes.

[0050]

[Table 1]

After dyeing, in order to remove the dye adhering to the fiber surface, reduction washing was carried out at 80 ° C. for 20 minutes in the bath shown in Table 2, followed by washing with water and drying.

[0052]

[Table 2]

The average single fiber fineness of the constituent fibers of the obtained woven fabric was 0.08 denier, and a polyester ultrafine fabric having no residual undivided fiber was obtained. Further, the visual density L * of the woven fabric was 39, which had a uniform appearance, and no warp or weft unevenness was observed.

[0054]

[Comparative Example 1] The same procedure as in Example 1 was carried out except that the pressure treatment was not performed. The weight loss rate of the obtained woven fabric was 26%. The average single fiber fineness of the constituent fibers of this woven fabric was 0.3 denier, and there were undivided fibers. The whiteness of this woven fabric was 87, and the luminous density L * when the woven fabric was dyed was 32, which had a lot of warp-like thread unevenness and had a low commercial value.

[0055]

Example 2 The procedure of Example 1 was repeated except that 2.5% by weight of lauric acid monoglyceride was added to the polyester matrix instead of the water-insoluble polyoxyethylene-based polyether.

The whiteness of the obtained woven fabric was 102, the average single fiber fineness of the constituent fibers was 0.09 denier, and a polyester ultrafine fabric having no residual undivided fibers was obtained.

The visual density L * of the woven fabric was 36, which had a uniform appearance.

[0058]

Comparative Example 2 The procedure of Example 2 was repeated except that the pressure treatment was not performed. The weight loss rate of the obtained woven fabric was 22%. The average single fiber fineness of this woven fabric was 0.4 denier, and an ultrafine fiber woven fabric could not be obtained. The whiteness of this woven fabric was 92, and the visual density L * when the woven fabric was dyed was 30.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a split split conjugate fiber.

FIG. 2 is a cross-sectional view showing an example of a sea-island type composite fiber.

[Explanation of symbols]

 A One component that constitutes the splittable conjugate fiber B The other component that constitutes the splittable conjugate fiber C Sea component D Island component

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area // D06M 101: 32

Claims (4)

[Claims] 1. An ultrafine fiber is produced by dissolving an easily soluble polymer in a split-split type composite fiber and / or a sea-island type composite fiber formed from at least two kinds of fiber-forming polymers having different solubilities. In this case, the composite fiber is pressed before the polymer is melted. 2. The method for producing an ultrafine fiber according to claim 1, wherein the conjugate fiber is a peelable split-type conjugate fiber comprising a polyester containing a polyoxyethylene-based polyether and a polyester having an ethylene terephthalate unit as a main repeating unit. 3. The method for producing an ultrafine polyester fiber according to claim 1, wherein the pressure is applied by a calender roll. 4. The method for producing an ultrafine polyester fiber according to claim 3, wherein the linear pressure applied is 5 to 60 kg / cm.