JPH0559615A - Production of ultrafine fiber - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a method for producing ultrafine fibers which has no problem in spinnability with an ordinary spinning machine, has excellent extractability of sea components, and has less sticking between ultrafine fibers. In a method for producing ultrafine fibers by solvent extraction of a sea component of a mixed spun fiber composed of two or more kinds of polymers having different solvent extractability, the weight fraction of the island polymer in the mixed spun fiber is 60% or less. , Melt spinning temperature, shear rate 1
Melt viscosity (MV _I ) of island polymer at 0 ³ sec ^-1
And the melt viscosity (MV _s ) of sea polymer is MV _I / MV
_s ≧ 4, MV _s ≧ 220 poise, sea polymer is low density polyethylene, and number average molecular weight is 5,000
A component obtained by previously blending 0 to 20,000 polyethylene glycol with a sea polymer in an amount of 2 to 10% by weight is used as a sea component.

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 fibers. More specifically, mixed spinning can be carried out without any special equipment, and the extractability of the mixed spun fiber after extraction with a solvent of the sea component polymer is good. The present invention relates to a method for producing ultrafine fibers which is free from sticking between the ultrafine fibers and has good openability.

[0002]

BACKGROUND OF THE INVENTION There are many known methods for obtaining ultrafine fibers by forming mixed spun fibers from two or more incompatible polymers and then removing at least one polymer from the mixed spun fibers. For example, Japanese Patent Publication No.
In Japanese Patent Publication No. 67, a method for producing a polyoxymethylene microfilament by removing nylon 6 or polyester and a method for producing a polypropylene microfilament by removing polystyrene or polyethylene are disclosed. Also, JP-A-61-25
Japanese Patent No. 2362 discloses a method for producing ultrafine fibers of aromatic polyester by removing polyethylene, polypropylene and polystyrene.

The present inventors have examined the combination of polyamide and polyethylene or polyester and polyethylene, and found that the spinnability was poor and that temperature adjustment under the spinneret was necessary (Japanese Patent Publication No. 42-11695). Problems such as difficulty in component extraction and adhesion between ultrafine fibers after sea component extraction occurred.

Further, in JP-A-49-529, a thermoplastic polymer having a solubility parameter of 10 (cal / cc) ^1/2 or less and 10 (cal / cc) ^1/2
There is disclosed a method in which a mixture mainly composed of a thermoplastic polymer having the above-mentioned values, and a mixture of polyethylene glycol as a fibrillation-promoting agent, is melt-mixed, and then formed into filaments, films or tapes, and fibrillated. However, it is described that with this method, only fibers having an extremely short fiber length can be obtained.

Further, Japanese Patent Publication No. 55-29166 discloses a method for producing ultrafine polyamide fibers by combining polyamide, polystyrene and polyethylene glycol in a certain specific ratio. But,
With this method, only those with severe interfiber adhesion were obtained.

[0006]

As described above, simply blending the island component with the sea component causes poor spinnability, and it is difficult to extract the sea component, especially the sea component attached to the surface of the island component. Or, the adhesion between the ultrafine fibers after the sea component extraction may be severe. In addition, the fiber length is very short, which limits its practical use. An object of the present invention is to provide a method for producing ultrafine fibers which has no problem in spinnability in a normal spinning machine, has good extractability of sea components, has less sticking between ultrafine fibers, and has a sufficiently long fiber length. Especially.

[0007]

The present invention provides a method for producing ultrafine fibers by solvent extraction of a sea component of a mixed spun fiber composed of two or more kinds of polymers having different solvent extractability, which is an island of the mixed spun fiber. weight fraction of the polymer is not less than 60% the melt spinning temperature under a ratio of melt viscosity of the melt viscosity (MV _I) and sea polymer island polymer at a shear rate 10 ³ sec ^-1 (MV _S) is MV _I / MV _S ≧ 4, and MV _S
≧ 220 poise, sea polymer is low density polyethylene, and number average molecular weight is 5,000 to 2
A method for producing ultrafine fibers, characterized in that a component obtained by previously blending 2 to 10% by weight (compared to the sea polymer) of polyethylene glycol of 10,000 to the sea polymer is used as the sea component.

Polyamide or polyester is preferably used as the island component of the present invention. As polyamide, nylon 4, nylon 6, nylon 6,6, nylon 7, nylon 6,10, nylon 11, nylon 1
Polyamides such as 2 or modified nylon can be mentioned, and one or more of these polymers can be selected. Above all, nylon 6 or nylon 6,
No. 6 is particularly preferable in view of various conditions such as thermal stability and melting temperature.

Examples of polyesters include polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene isophthalate, polyethylene naphthalate and modified polyesters thereof.

The polymer constituting these island components should have a weight fraction of 60% or less, preferably 40 to 55%. When the weight fraction of the island polymer exceeds 60%, it enters the phase inversion region and it becomes impossible to obtain ultrafine fibers.

Further, at the spinning temperature, the shear rate is 10 ³ sec.
It is necessary that the ratio of the melt viscosity (MV _I ) of the island polymer and the melt viscosity (MV _S ) of the sea polymer at ^-1 is MV _I / MV _S ≧ 4, preferably 6 to 15. MV _I / M
If V _S is less than 4, ultrafine fibers cannot be obtained.

Further, it is necessary that MV _S ≧ 220 poise, preferably 300 to 600 poise. MV
_{If S} is less than 220, spinning becomes difficult.

In the present invention, low density polyethylene is used as the sea polymer and has a number average molecular weight of 5,0.
A component obtained by previously blending polyethylene glycol of 0 to 20,000 with a sea polymer in an amount of 2 to 10% by weight (based on the sea polymer) is used as a sea component. When the number average molecular weight of polyethylene glycol is less than 5,000, single yarn breakage occurs and spinning becomes difficult. On the other hand, when it exceeds 20,000, the dispersion of polyethylene glycol in the sea component is poor and the spinnability is deteriorated. In addition, it is preferable that an alkyl group or the like is bonded as a side chain in the polyethylene glycol molecule because the melt viscosity of the island polymer can be prevented from lowering.
In addition, the molecule may contain a polypropylene oxide chain or the like.

The addition of polyethylene glycol not only improves the fibrillation property, but also increases the fiber length of the island polymer having a strong spinnability, so that the spinnability is also improved. The amount of polyethylene glycol added is 2 for low density polyethylene.
10 to 10% by weight, preferably 3 to 8% by weight. If the amount of polyethylene glycol added is less than 2% by weight, such an effect cannot be exhibited, while if it exceeds 10% by weight, spinnability deteriorates.

Further, by blending polyethylene glycol into low density polyethylene first, the extractability of the sea component by the solvent is improved. Moreover, since the bleed-out polyethylene glycol layer is formed at the interface between the island polymer and the sea polymer, the sea polymer on the surface of the island polymer is quickly extracted, and the adhesion of the ultrafine fibers after the sea component extraction is prevented. Therefore, it is considered that an ultrafine fiber having good openability can be obtained.

The low density polyethylene as a sea polymer used in the present invention means a density of 0.91 obtained by a high pressure polymerization method.
It refers to polyethylene of 0 to 0.925, and does not include polyethylene obtained by the medium and low pressure polymerization method.

As a method for mixing the island component and the sea component, low-density polyethylene and polyethylene glycol are first blended with a chip blender or the like to form chips, and the island component polyamide or polyester is chip-blended, followed by ordinary melt spinning. The method of introducing into the apparatus, the low density polyethylene and polyethylene glycol are fed by the first feeder of the melt spinning apparatus and blended first, and then the second
A method of supplying polyamide or polyester with a feeder can be adopted. When mixing, if necessary,
Antistatic agents, pigments, heat stabilizers and the like can also be added.

The temperature of melt spinning is preferably 240 to 260 ° C. when the island component is polyamide and 275 to 295 ° C. when the polyester is polyester. The spinneret diameter and the spinning speed may be set to meet the requirements of the average single yarn denier of the ultrafine fibers finally obtained. The stretching temperature is preferably 90 to 100 ° C., and the stretching ratio is preferably around 3 times.

Polyethylene and polyethylene glycol are dissolved and removed from the mixed spun fiber obtained as described above to obtain ultrafine fibers. The polyethylene and polyethylene glycol can be dissolved and removed by immersing the mixed spun fiber in a solvent such as toluene, xylene, trichlene, or decahydronaphthalene under heating.
The extraction of polyethylene and polyethylene glycol by solvent extraction may be carried out in the state of yarns of mixed spun fibers, or may be carried out after forming a cloth such as a non-woven fabric, a woven fabric or a knitted fabric. Further, it may be performed after the raising process or the resin process.

The ultrafine fibers thus obtained have a thickness of 0.
It is in the range of 003 to 0.05 denier and the fiber length is 50.
Most are mm or larger. Such a fabric has a very soft touch, and a raised fabric surface has a suede-like texture, and can be used for applications such as a base fabric of high-grade artificial leather and a high-grade knit fabric.

[0021]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In addition, "%" in an Example shows "weight%."

Example 1 Nylon 6 chips having a melt viscosity of 3,000 poise measured at a melting temperature of 255 ° C. and a shear rate of 10 ³ sec ⁻¹ , and a low-density polyethylene having a melt viscosity of 500 poise had a number average molecular weight of 8, 6000 polyethylene glycol 6% kneaded into polyethylene, a nylon 6 fraction 40
%, Chip blended, introduced into a normal melt spinning device with 36 spinning holes, spinning temperature 255 ° C., winding speed 5
By spinning at 00 m / min and stretching 3 times, a drawn yarn of a mixed spun fiber having a single fiber denier of 7 denier was obtained. The spin drawability of this mixed spun fiber is shown in Table 1.

A non-woven fabric was made from the drawn yarn of the mixed spun fiber, and polyethylene and polyethylene glycol were extracted and removed with xylene at 80 ° C. to obtain a non-woven fabric composed of a fiber bundle of ultrafine polyamide. Table 1 shows the spreadability and single yarn denier of this ultrafine fiber.

Comparative Example 1 Example 1 except that nylon 6 chips, polyethylene chips and polyethylene glycol were simultaneously chip blended.
A non-woven fabric made of a fiber bundle of ultrafine polyamide was obtained by the same process as described above, but adhesion between the fibers was observed.

Comparative Example 2 A non-woven fabric comprising a fiber bundle of ultrafine polyamide was obtained by the same steps as in Example 1 except that polyethylene glycol was kneaded into nylon 6 first, but lotus root-like thick fibers were partially formed. ..

Comparative Example 3 Example 1 except that polyethylene glycol was not added.
A non-woven fabric composed of an ultrafine fiber bundle was obtained in the same manner as in. The spinnability was poor and special cooling under the spinneret was required. Also,
After the extraction with xylene, the ultrafine fibers were poor in openability, and only fibers with severe adhesion were obtained.

Example 2 Nylon 6 chips having a melt viscosity of 2,000 poise measured at a spinning temperature of 255 ° C. and a shear rate of 10 ³ sec ⁻¹ , and a low-density polyethylene having a melt viscosity of 500 poise had a number average molecular weight of 8, 000 polyethylene glycol (PEG)
4% of chips were blended at a weight ratio of 60:40, and a nonwoven fabric composed of an ultrafine fiber bundle was obtained in the same process as in Example 1. The conditions and results at this time are shown in Table 1.

Comparative Example 4 A nonwoven fabric made of a nylon 6 fiber bundle was obtained in the same manner as in Example 2 except that the weight ratio of the nylon 6 chip and the low density polyethylene chip was 65:35. The conditions and results at this time are shown in Table 1.

Comparative Example 5 Nylon 6 fibers were used in the same manner as in Example 2 except that nylon 6 having a melt viscosity of 2,000 poise measured under the same conditions as in Example 2 and low density polyethylene having 600 poise were used. A nonwoven fabric consisting of a bundle was obtained. The conditions and results at this time are shown in Table 1.

It can be seen from Table 1 that when the island component fraction is 60% or less and the melt viscosity ratio is 4 or more, ultrafine fibers having good openability can be obtained.

Example 3 Low density polyethylene (PE) having a melt viscosity of 220 poise measured at a melting temperature of 285 ° C. and a shear rate of 10 ³ sec ^-1.
Using a chip 60% and a polyethylene terephthalate (PET) 40% to which 4% of polyethylene glycol (PEG) having a number average molecular weight of 20,000 was added, a spinning temperature of 28
A nonwoven fabric composed of PET fiber bundles was obtained at 5 ° C. by the same process as in Example 1.

Comparative Example 6 The same procedure as in Example 3 was carried out except that low density polyethylene having a melt viscosity of 180 poise measured under the same conditions as in Example 3 was used, but a spinning failure occurred.

Examples 4 to 5 and Comparative Examples 7 to 8 Nylon 6 chips having a melt viscosity of 3,000 poise measured at a melt viscosity of 255 ° C. and a shear rate of 10 ³ sec ⁻¹ and low density polyethylene having a melt viscosity of 500 poise. Polyethylene glycol (PEG) having a number average molecular weight of 8,000 is contained in (PE) as shown in Table 1, 1, 2, 10,
The same process as in Example 1 was performed using the chip added with 11%.

With the composition of the present invention, the intended ultrafine fibers were obtained, but with polyethylene glycol 1%, interfiber sticking was severe, and with polyethylene glycol 11%, single yarn breakage occurred. The conditions and results at this time are shown in Table 1.

[0036]

[Table 1]

[0037]

Industrial Applicability According to the present invention, a mixed spun fiber can be produced with extremely good spinnability, and a solvent-extractable polymer of the sea component polymer of the mixed spun fiber, particularly an excellent extractability of the sea polymer on the island polymer surface can be obtained. Further, the obtained ultrafine fibers have good openability with less interfiber sticking.

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location D06M 13/07 // D01F 6/46 C 7199-3B

Claims (1)

[Claims] 1. A method for producing ultrafine fibers by solvent extraction of a sea component of a mixed spun fiber composed of two or more polymers having different solvent extractability, wherein the weight fraction of the island polymer in the mixed spun fiber is 60%. And the melt viscosity (M) of the island polymer at a shear rate of 10 ³ sec ^-1 at the melt spinning temperature.
V _I ) and the melt viscosity (MV _S ) of the sea polymer are MV _I
/ MV _S ≧ 4, satisfying MV _S ≧ 220 poise,
In addition, the sea polymer is low density polyethylene, and the component in which polyethylene glycol having a number average molecular weight of 5,000 to 20,000 is blended with the sea polymer in an amount of 2 to 10% by weight (compared to the sea polymer) is used as the sea component. A method for producing an ultrafine fiber, comprising: