JP2954827B2 - Production method of ultrafine fiber - Google Patents

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 an ultrafine polyester fiber from an exfoliated splittable conjugate fiber in which no unsplit fibers remain.

[0002]

2. Description of the Related Art Synthetic fibers have a wide range of uses due to their excellent properties. In particular, fabrics made of ultrafine fibers having a single fiber fineness of 0.1 denier or less are being expanded to various uses.

[0003] Conventionally, as a method for producing a cloth made of ultrafine fibers, a split-split conjugate fiber (hereinafter referred to as split-split fiber) having a fiber cross-sectional shape in which polyethylene terephthalate, which is a fiber-forming polymer, and nylon 6 are alternately arranged in a radial pattern. Japanese Patent Application Laid-Open No. H11-163873 discloses that a fabric composed of a mold composite fiber or a composite fiber) is directly subjected to alkali weight reduction, and an interface thereof, that is, a bonding interface of a polymer is peeled off to obtain an ultrafine fiber fabric (hereinafter referred to as melting). It is disclosed in JP-A-55-116874. However, in this method, the following three problems are inherent.

A. Since it is difficult to completely separate the peelable splittable conjugate fibers constituting the fabric by melting, unsplit fibers tend to remain, and the apparent dyeing properties of the unsplit portion and the split portion are different. Easy to cause staining spots on the skin.

B. If the remaining undivided fibers are eliminated, the processing time for alkali weight reduction is prolonged, thereby increasing the weight loss rate. However, in this case, the physical properties of the fiber after the alkali weight loss may be reduced, and the fiber may not be able to withstand actual use.

C. The composite fiber after the cracking treatment almost maintains the arrangement before the cracking, and exhibits a so-called bunched state, and the characteristics of the composite fiber before the cracking partially remain, and the flexibility of the cloth made of the ultrafine fiber remains. Sex is inhibited.

[0007] Therefore, it is disclosed in Japanese Patent Application Laid-Open No. 56-1650 to improve the flexibility of the cloth by subjecting the obtained cloth to pressure between opposing rolls after performing the splitting treatment described in the above publication.
No. 69 proposes this. In this method, the pressure after the splitting treatment disturbs the above-mentioned convergence state and causes rearrangement of the fiber group, so that the above-mentioned problem c is solved.

However, it has been found that, even in this method, the problem a has been left unsolved. In other words, in the step of performing the pressure treatment after the splitting process, the problem of the undivided portion remaining after the splitting process described in the above a has inevitably remained.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to improve the cracking property of a split-split type conjugate fiber so that an undivided fiber remains free of ultrafine fibers. Is to provide.

[0010]

Means for Solving the Problems As a result of intensive studies conducted by the present inventors to achieve the above-mentioned object, before the above-mentioned split-split type conjugate fiber is split, the fiber is subjected to a pre-pressurizing treatment. When applied, it was found that cracks were formed at the joint interface, and that the meltability of the fiber as a whole was significantly improved.

Thus, according to the present invention, formed from at least two fiber-forming polymers having different solubilities,
In addition, in producing a fine fiber by dissolving the easily soluble polymer in the exfoliated splittable conjugate fiber having a fiber cross-sectional shape in which these polymers are radially alternately arranged, before dissolving the easily soluble polymer, A method for producing an ultrafine fiber, characterized by improving the potential splitting property of the exfoliated splittable conjugate fiber in a subsequent dissolution treatment by pressing the exfoliated splittable conjugate fiber to form a crack at the joint interface thereof. Is provided.

Hereinafter, the exfoliated splittable conjugate fiber used in the present invention will be described. As used herein, the term “split-split conjugate fiber” refers to a fiber cross-sectional shape in which one component A divides the other component B into a plurality of components and the components are radially alternately arranged as shown in FIG. Composite fiber.

The combination of components A and B in the exfoliated splittable conjugate fiber formed from at least two types of fiber-forming polymers having different solubilities may be appropriately set according to the conditions of the melting and the like. For example, polyester, polyamide,
A modified polymer obtained by copolymerizing or blending the third component with polyethylene or polystyrene may be used.

Among them, preferred are split-split type composite fibers using a polyester containing a polyoxyethylene-based polyether as the component A and using a polyester having an ethylene terephthalate unit as a main repeating unit as the component B.

Of course, these may be polymers containing any additives such as antioxidants, ultraviolet absorbers, heat stabilizers, flame retardants, fluorescent brighteners, titanium oxide, coloring and inert fine particles. good.

The form of the exfoliated splittable conjugate fiber may be appropriately set according to the desired single fiber shape and single fiber fineness, and the shape may be any of filament, false twisted yarn and spun yarn.
If necessary, synthetic fibers other than polyester fibers, natural fibers such as cotton and wool, recycled fibers such as rayon, and polyethylene terephthalate-based polyester as hard segments, and block copolymers containing polyoxybutylene glycol-based polyester as soft segments. It may be used in the form of cross weaving, cross knitting, cross spinning or blending with polyetherester elastic fibers.

Next, the mode of pressurization before the melting treatment, which is the most significant feature of the present invention, will be described in detail. The exfoliated splittable conjugate fiber is pressed in a yarn state before and after drawing after spinning, or is pressed in a state of a fabric knitted and woven into an arbitrary structure. Thereafter, when the exfoliated splittable conjugate fiber is subjected to a dissolution treatment with a solvent of any of the fiber-forming polymers constituting the fiber, it is very easily split mainly in the fiber axis direction to become an ultrafine fiber. Therefore, it is indispensable to carry out the pressing before the dissolution treatment. For example, it may be carried out before or after any of the steps of greige, refining, presetting, washer, or high-temperature / moisture heat treatment (relaxation). Here, the ultrafine fibers are those having a single fiber fineness of less than 0.1 denier. The single fiber fineness of the ultrafine fibers obtained by using the method of the present invention is the single fiber fineness or shape of the fiber before cracking,
It depends on the conditions of pressurization or melting, etc.
It has been confirmed that up to about 1 denier can be obtained.

Preferred modes of pressurization include cotton,
A calendering process using a roll made of metal or the like is used. When a so-called friction roll having different upper and lower roll speeds is used, a particularly remarkable cracking effect is exhibited when the alkali is reduced in weight.

The roll to be used may be a flat roll or an embossed roll having a carved pattern according to the purpose.
It is appropriately selected.

The pressing temperature is preferably a temperature not higher than the secondary transition point of the composite fiber. The above secondary transition point is a value measured by DSC, and when a plurality of secondary transition points are observed for each of the polymer components constituting the conjugate fiber, the average value is used as the secondary transition point. And If the pressing temperature exceeds the second transition point, the composite fiber is deformed.

The pressure at this time is a linear pressure of 5 to 60.
Kg / cm is preferred. If the linear pressure is less than 5 kg / cm, the fiber may not be sufficiently cracked even if the cracking treatment is performed. On the other hand, if the linear pressure exceeds 60 kg / cm, the fiber becomes flat and the gloss increases. May not be practical.

Here, if the entire surface of the fabric is pressed uniformly using a calender roll or the like, all the conjugate fibers constituting the fabric are melted, so that the undivided fibers remain uniform. A very fine fiber fabric is obtained. Therefore, the main light reflection on the cloth surface changes from specular reflection to diffuse reflection, and the cloth has a high whiteness that has not been obtained until now.

By appropriately distributing the pressing conditions in the cloth, it is possible to obtain a cloth in which divided fibers and undivided fibers are mixed. In this embodiment, as a pressing method other than the calendering process, a stone wash process, a process using an embossing roll, a process for patterning a cloth using a pencil or the like, and the like can be mentioned.

When the pressure is a stone wash process,
Since the fibers constituting the fabric are partially and randomly pressed by solids such as stones, a random pattern can be imparted to the fabric by reducing the alkali after performing such processing.

When the pressure is applied only to a part of the cloth using an embossing roll or the like, the fibers constituting the pressed part are preferentially fined by the fusing treatment. The apparent dyeing properties and gloss change in comparison with the pressurized portion (usually, the extremely thinned portion appears to be lightly dyed), and it is possible to impart an embossing roll pattern to the fabric.

Furthermore, when a pattern is drawn on a cloth using a pencil or the like, if the applied pressure is sufficiently high, only the fibers in the pressurized portion are preferentially ultra-fine due to alkali reduction, and an arbitrary pattern can be formed. Can be granted.

Next, the cracking treatment after pressurization in the present invention will be described. The type of solvent to be used and the processing conditions may be appropriately selected depending on the constituent components of the conjugate fiber. .

The alkaline aqueous solution used at this time is exemplified by aqueous solutions of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and the like. A surfactant or the like which promotes penetration into the material may be added to reduce the alkali.

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

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

[0031]

In the present invention, by applying a particularly high pressure to the conjugate fiber before the splitting treatment, the splitting occurs very easily during the subsequent splitting treatment, so that a uniform ultrafine fiber cloth can be obtained.

As described above, the pressure treatment in the present invention is as follows.
It can be said that it exhibits a function of improving the potential splitting property of the conjugate fiber in the subsequent cracking treatment. The mechanism of this function has not been fully elucidated yet, but when pressure is applied, cracks are formed at the bonding interface of the polymer constituting the composite fiber, and when the polymer is dissolved in a solvent for the polymer, the cracks form. It is presumed that weight loss progresses preferentially, and the composite fibers are easily cracked to become ultrafine fibers.

By the way, in the present invention, it has been confirmed that the rate of weight loss of the conjugate fiber is several times faster than the case where no pre-pressurization is performed.

[0034]

The present invention will be specifically described below with reference to examples. The following evaluation method was used in the examples.

(1) Luminous density L * value Macbeth 2020+ (made by Colmorgen, USA)
Color with a light source D65 and a 10 ° visual field using JIS Z
Brightness index L of UCS color system according to 8730-1980
* Value was calculated. The smaller the L * value, the deeper the color is dyed, indicating a higher luminous density.

(2) Whiteness (L * -b * value) The cloth with increased weight loss (undyed cloth) was measured in the same manner as the above luminous density, and the L * value and the chromaticity index b * value were calculated. . The greater the L * -b * value, the greater the whiteness.

Example 1 Polyethylene terephthalate having an intrinsic viscosity of 0.45,
A side-by-side conjugate filament of 85 denier / 24 filament, in which polybutylene terephthalate having an intrinsic viscosity of 0.85 was composited at a ratio of 40:60, was obtained.

On the other hand, as a component A, a transesterification reaction of a dicarboxylic acid component and ethylene glycol was carried out, and then three alkyl groups each having an average carbon number of 21 were bonded to both ends of a borooxyethylene chain, each having an average molecular weight of 12,000. A water-insoluble polyoxyethylene-based polyether was added to the polyester matrix in an amount of 3% by weight, and then a polyester polymerized according to a conventional method was used. As the B component, a polyethylene terephthalate having an intrinsic viscosity of 0.64 was used. , Split-type solid composite fibers having the shape shown in FIG. 1 (however, A and B each have 32 layers, 180 denier / 4
0 filaments).

Here, “water-insoluble” means 100 g of pure water.
5 g of the polyoxyethylene-based polyether is put therein, heated at 100 ° C. for 60 minutes, cooled to room temperature, and naturally filtered by a JIS standard 5 type A filter paper, and 90% or more is filtered out. .

Next, the conjugate filament and the splittable conjugate fiber are aligned and supplied to an interlace nozzle, and the overfeed rate is 2.5% and the pneumatic pressure is 2.8K.
After the fiber was mixed at g / cm, a simultaneous false twisting process was performed at a false twist speed of 350 m / min, a surface speed of the false twist disk of 650 m / min, a false twist temperature of 135 ° C., and a draw ratio of 2.0 times.

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

Next, after weaving a plain fabric using the yarn as a background, scouring, relaxing, drying, and presetting were performed by a conventional method.

Subsequently, the above-mentioned woven fabric was cut into 10 pieces of cloth using a calendering machine having a mirror roll and a paper roll.
Immediately after immersion in ice water at a temperature of 10 ° C and a linear pressure of 30Kg
/ Cm and a pressure of 10 m / min.

The obtained woven fabric was boiled for 45 minutes in an aqueous sodium hydroxide solution having a concentration of 20 g / l to reduce the weight by 40%. The whiteness of the obtained woven fabric was 104. continue,
Dyeing was carried out at 130 ° C. for 60 minutes in the dye bath shown in Table 1.

[0045]

[Table 1]

After dyeing, in order to remove the dye adhering to the fiber surface, the fibers were reduced and washed in a bath shown in Table 2 at 80 ° C. for 20 minutes, and then washed with water and dried.

[0047]

[Table 2]

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

Comparative Example 1 The procedure of Example 1 was repeated except that the pressure treatment was not performed. The weight loss rate of the obtained fabric is 26.
%Met. The average fiber denier of the constituent fibers of this woven fabric was 0.3 denier, and there were undivided fibers. The whiteness of this fabric was 87. Further, the luminous density L * at the time of dyeing the woven fabric was 32, and there were many warp-like thread unevennesses, and the commercial value was low.

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 in place 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 an ultrafine polyester fabric having no undivided fibers remaining was obtained. The luminous density L * of the fabric is 36.
And had a uniform appearance.

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 fabric is 2
2%. The average single fiber fineness of this woven fabric was 0.4 denier, and an ultrafine fiber woven fabric was not obtained. The whiteness of this fabric was 92. The luminous density L * when the woven fabric was dyed was 30.

[Brief description of the drawings]

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

[Explanation of symbols]

 A One component constituting the splittable conjugate fiber B The other component constituting the splittable conjugate fiber

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) D06M 11/84 D01F 8/14

Claims (5)

(57) [Claims] Claims: 1. A fiber formed from at least two fiber-forming polymers having different solubilities , and these polymers are
In the exfoliated splittable conjugate fiber exhibiting a fiber cross-sectional shape alternately arranged in a radial pattern, upon dissolving the easily soluble polymer to produce an ultrafine fiber, before dissolving the easily soluble polymer ,
The split-split conjugate fiber is pressurized to crack the joint interface.
By forming a crack, the exfoliation in the subsequent dissolution treatment is performed.
A method for producing ultrafine fibers, characterized by improving the potential splitting properties of separable conjugate fibers . 2. A fiber-forming polymer which forms the composite fibers
2. The method for producing ultrafine fibers according to claim 1, wherein the polyester is a polyester containing a polyoxyethylene-based polyether and a polyester mainly containing ethylene terephthalate units. 3. The method according to claim 1, wherein the pressing is performed by a calender roll. 4. The method according to claim 1, wherein the temperature of the pressurization is different from the second transition point of the composite fiber.
4. The production of the ultrafine polyester fiber according to claim 3, which is:
Method. 5. The method for producing an ultrafine polyester fiber according to claim 3 , wherein the applied linear pressure is 5 to 60 kg / cm.