WO1992015734A1

WO1992015734A1 - Composite fiber having porous sheath part

Info

Publication number: WO1992015734A1
Application number: PCT/JP1992/000261
Authority: WO
Inventors: Isamu Takahashi; Yoshio Iida
Original assignee: Ube-Nitto Kasei Co., Ltd.
Priority date: 1991-03-05
Filing date: 1992-03-05
Publication date: 1992-09-17
Also published as: EP0528048A4; EP0528048A1

Abstract

A composite fiber having a strength sufficient for practical use, easily going through carding process, and resistant to higher temperature when being processed into non-woven fabric or used as a non-woven fabric, which fiber is provided with a sheath part composed of porous polyolefin series synthetic resin and a non-porous core part. An apparent cross-sectional area of said sheath part is from 20 to 80 % of the entire cross-sectional area of the fiber. Said polyolefin series synthetic resin is preferably high density polyethylene or polyproylene. Said resin is made porous by mixing it with paraffin wax which is then removed after spinning process. The core part is selected from polyprolylene resin, nylon of low melting point, and polyester of low melting point.

Description

Specification

Composite fiber with porous sheath

Technical field

TECHNICAL FIELD The present invention relates to a composite fiber having a sheath portion formed by making a polyolefin-based synthetic resin porous, and more particularly to a porous fiber having practically usable fiber strength and force-treatability.

Background art

Conventionally, as a synthetic fiber having micropores, a porous water-absorbing polyester fiber or the like has been used as a fiber for clothing, and water absorbing performance has been provided to improve comfort. On the other hand, polyolefin microporous fibers have been developed as various kinds of hollow fiber membranes for separation, and are widely used in the fields of medicine, engineering, and consumer use. Many such microporous fibers have been developed in the past, but there were technical difficulties in controlling the shape or size of the holes.

For example, as a polyolefin-based porous fiber, propylene or polyethylene is spun hollow at low temperature and high draft, and after heat treatment, is stretched to a predetermined magnification or stretched at cryogenic temperature. Then, it is known to obtain hollow fibers having strip-shaped voids by so-called lamellae, but these are mainly used as the above-mentioned hollow fiber membranes and the like. The denier is relatively large and the pore size is relatively small, making it unsuitable for applications that make use of functions such as liquid retention and ripening.

Thus, the present inventors have studied porous fibers having relatively low denier, and as the porosity of the porous fiber is increased, the strength of the arrowhead fiber is significantly reduced, which causes a practical problem. Know that there is I got it. In other words, in the case of fibers with high porosity, the strength is greatly reduced, and when the fibers are processed into a nonwoven fabric, woven fabric, or the like, only low-strength fibers can be obtained. Further, for example, even if the porous fiber is made of high-density polyethylene and has a porosity of 30 to 50%, it is difficult to impart crimp in the fiber manufacturing process, and therefore, it is necessary to use a card. At the time of processing, there is a problem that the fiber sinks into the card cylinder, the web connection is poor, and uniform carding cannot be performed.

In addition, heat resistance is required for certain applications. For example, polyethylene-based porous fibers need to be sufficiently resistant to use in boiling water and disinfection by steam. It is mixed with a binder fiber consisting of a composite fiber of polyethylene fiber and polyethylene propylene, applied to a card and made into a web, and then passed through a heat roller such as an emboss roller or a force render roller to be thermally bonded. When a nonwoven fabric is used, it is necessary to prevent the porosity from decreasing due to heat shrinkage and to prevent the nonwoven fabric from shrinking when the fabric is entirely porous. In this case, even in the case of a polypropylene-based porous fiber, the overall effect is about 130 V in the case of a porous fiber, and shrinkage increases the effect and decreases the porosity. However, the surface temperature of the heat roller could not be raised to 120 ° C. or more even when the fabric was formed, and the productivity of the nonwoven fabric was low. Accordingly, the present inventors have conducted intensive studies on the practical strength, good card permeability, and the structure of polyolefin-based porous fibers that can withstand higher temperatures during nonwoven fabric manufacturing and nonwoven fabric use, and completed the present invention. did.

Disclosure of the invention

The composite fiber according to the present invention is a sheath-core type composite fiber comprising a sheath made of a polyolefin-based synthetic resin made porous and a nonporous core, wherein the sheath has an apparent appearance. The basic feature is that the cross-sectional area is in the range of 20 to 80% of the total cross-sectional area of the fiber. Polyethylene and polypropylene are suitable as the polyolefin resin that can be used in the present invention. In the case of polyethylene, the melt flow rate is determined by a measurement method according to ASTM D12238. High-density polyethylene with an (MFR) value of 0.3 to 20 g / lO min (HDPE) is recommended. Further, it is preferable that the polypropylene has a density of about 0.90 or more and an MFR value in the range of 0.5 to 20 gZ10 minutes by the same measuring method.

When the MFR is out of the above range, the melt viscosity during melt spinning after mixing with paraffin-pack at the time of forming the porous body becomes inadequate, and a problem occurs during spinning. To make the sheath porous, for example, when melt-spinning the sheath, after mixing and spinning a paraffin wax mainly composed of a saturated aliphatic compound, a hydrocarbon compound, etc. This can be achieved by eluting the wax with a solvent.

The resin component used in the core of the composite fiber of the present invention has a melting point difference from a homopolymer such as high-density polyethylene or polypropylene or a polyolefin resin such as copolymer, or HDPE in the sheath. Approximately 70 or less low melting point or low melting point Polyester resin and the like can be mentioned, but polypropylene homopolymer is desirable from the viewpoint of fiber physical properties and suitability for composite spinning. The cross-sectional area ratio between the sheath and the core should be such that the apparent cross-sectional area of the sheath is within the range of 2ΟδΟ ^ of the total cross-sectional area of the fiber. When the value is less than 20 <¾, the ratio of the porous portion is small, and the function of the porous fiber cannot be sufficiently exhibited.When the content exceeds 80%, the strength retention by the core is insufficient and the strength becomes practical. I can't reach it.

In the present invention, the apparent cross-sectional area of the sheath is a cross-sectional area defined by the maximum outer periphery of the sheath and the outer periphery of the core, and is an area including a void portion. The total cross-sectional area of the fiber is the sum of the apparent cross-sectional area of the sheath and the cross-sectional area of the core.

Since the composite fiber having a porous sheath portion of the present invention is composed of a porous sheath portion and a solid core portion, the crimping is performed on the core portion in the crimping process to the fiber. Therefore, crimping is sufficient, and strength can be ensured by the core, so that entanglement between single fibers is possible, and problems of card suitability and strength, which have been problems in the past, are effective. Can be resolved.

In addition, since the composite fiber of the present invention is composed of a porous sheath and a solid core, the core suppresses shrinkage when heated, so that the shrinkage of the porous sheath is entirely reduced. It becomes smaller than the case where it is made of a porous material, the decrease in the porosity of the porous sheath portion due to heating is small, and the heat resistance of the entire composite fiber is improved.

Hereinafter, preferred embodiments of the present invention will be described.

Example 1

HDPE with MFR value of 5.5 g '10 min as raw material for sheath (Mitsui Petrochemical: Hi-Zex 220 J) 100 parts by weight, density 0.78 g / cc, melting point 59 ° C paraffin wax (Nippon Oil 135 degree paraffin ) After mechanically mixing with 100 parts by weight, put them in a flat bottomed container, put them in an oven of 150 hours for 2.5 hours, make them homogeneously compatible, cool and solidify. This was crushed to prepare a raw material for melt spinning.

On the other hand, as a raw material for the core part, polypropylene (TS365, manufactured by Ube Industries, Ltd.) with an MFR value of 8 OgZl0 was used, and two units with a screw diameter of 32 mm were used. The above-mentioned raw material for the sheath portion is supplied to the extruder for the sheath portion by a sheath-core composite spinning device which is composed of an extruder and has a composite nozzle of 0.40 × 500 H attached thereto. An undrawn yarn of 10 denier was spun at a nozzle temperature of 170 ° C. and a spinning speed of 400 m / min with a core cross-sectional area ratio of 5: 5.

At this stage, if the paraffin wax is extracted, the porosity will be about 15%.

The undrawn yarn is bundled to about 20,000 denier, and the first drawing roller speed is 8 m minutes and the second drawing roller speed is 32 mZ minutes under a 100 ° C. atmosphere using a drawing roller. And stretched 4 times and wound up on a bobbin.

Next, the fiber wound on the bobbin is subjected to a constant-length heat treatment in an oven set at 110 ° C. for one hour, and then crimped at a rate of 12 pieces / inch using a lid box type crimper. After crimping with a target of, this fiber is pressed to about 51 mm to make it into a short fiber form, which is then put into a Soxhlet extractor and sheathed with n-hexane. Extract the paraffin mix of the Was done.

The resulting composite fiber had a denier of 2.5 densities, a strength of 2.59 g Zd, an elongation of 150 ° C., a number of crimps of 12.5 pieces, an inch, and a porosity of 35.3%. Was. This was passed through a test card machine, SC-360DR manufactured by Daiwa Kikai Co., Ltd., and was tested for force-passability. The porosity was calculated from the following equation.

Diameter denier one weight denier

Porosity (%) = X 100

-Denier diameter π

Diameter denier = 1 R ² X i) ₀ x 9 0 0 0 X l 0 ⁵

Four

R: Apparent diameter after paraffin wax extraction (cm) Weight of core and weight of sheath

P 0 =

Core volume + sheath resin volume

Example 2

In the same manner as in Example 1 except that the same sheath material and core material as in Example 1 were used, the cross-sectional area ratio of the sheath core was 8: 2, and the nozzle temperature was 160 ° C. After spinning 10 denier undrawn, and then drawing, heat treatment, crimping, and pressing as in Example 1, this was put into a Soxhlet extractor, and the sheath portion was similarly drawn. Porosity was performed.

The obtained fiber had a denier of 2.1, a strength of 1. gsg./d, and an elongation.

8 6 ° ύ, number 1 three crimped, 'inch was porosity 4 8.8 ⁰ 6. When the force passing property of this fiber was tested, the sagging of the web was slightly observed compared to Example 1, but the card workability was actually higher. It was judged that there was no problem in use.

Examples 3 and 4

The same material as that of Example 1 was used for the sheath portion, and polypropylene having an MFR value of 48 (Ube Industries, Ltd .: ZS-1238) was used as the core material. The one having a core ratio of 7: 3 (Example 3) and the other having a core ratio of 2: 8 (Example 4) were spun. In Example 4, the nozzle temperature was set at 200 ° C., and the other conditions were the same as in Example 1 for both Examples 3 and 4.

The composite fiber obtained was that of Example 3, 2.2 denier. The strength was 2.15 g / d, the elongation was 95, the porosity was 46.5%, and that of Example 4 was 3.1 denier, strength 3.10 g Zd, elongation 150%, porosity 17.0%, all of which have good cardability.

Example 5

The same raw material as in Example 1 was used for the sheath, and the melting point was 176 to 18 (low melting point nylon of TC (Ube Industries, Ltd .: 3035U)) for the core, and the sheath-to-core ratio was 5: 5. A composite fiber was obtained in the same manner as in Example 1 except that a 10-denier undrawn yarn was obtained at a nozzle temperature of 170.

The composite fiber had 2.4 denier, a strength of 2.36 g Zd, an elongation of 180%, and a porosity of 33.8 <¾, and had good force permeability. Comparative Examples 1 and 2

Without using multi-spinning equipment, a 0.4-øX160-hole nozzle was attached to a single-spin spinning machine with a screw diameter of 25 mm, and a 10-denier nozzle with a nozzle temperature of 144 was used. After spinning the drawn yarn, drawing A porous arrowhead fiber was obtained in the same manner as in Example 1 except that the magnification was 3 times (Comparative Example 1) and 4 times (Comparative Example 2). The fiber obtained in Comparative Example 1 had 2.2 denier, strength 1.10 g / d, elongation 270 96, porosity 45, and the fiber obtained in Comparative Example 2 had 1.7 denier, strength. 1.74 gZd, elongation 130%, porosity 37. ό) In both Comparative Examples 1 and 2, the cardability was quite poor, and it was difficult to carry out carding alone.

Example 6

Polypropylene with an MFR value of 310 minutes (Ube Industries, Ltd .: YK121) 100 parts by weight and paraffin wax (Nippon Oil Co., Ltd .: 135 ° paraffin) After 100 parts by weight were mechanically mixed with the mixture, the mixture was placed in a flat-bottomed container and placed in a 180 ° C oven for 2.5 hours to allow both to be uniformly mixed, and then cooled. It was solidified and pulverized to obtain a sheath material for melt spinning. The core is made of polypropylene (MFR value: 48, manufactured by Ube Industries, Ltd .: ZS-1238), and is composed of two extruders with a screw diameter of 32 mm. The above-mentioned raw material for the sheath portion is supplied to the extruder for the sheath portion by the sheath-core compound spinning device having a composite nozzle of 0.4 øX500H attached, and the cross-sectional area ratio of the sheath core is set to 8 As a ratio of 2, a 10-denier undrawn yarn was spun at a nozzle temperature of 200 and a spinning speed of 400 minutes.

The undrawn yarns are bundled to about 20,000 denier, and the first drawing roller speed is 8 m / min and the second drawing port speed is 24 m / min by a drawing roller in an atmosphere of 100 ° C. The film was stretched three times and wound on a bobbin. Next, the fiber as wound on this bobbin is heat-treated for 1 hour in an oven at 130 ° C, and then 12 pieces of Z-inch with a staffing box type crimper. After crimping with the number of crimps as a target, this fiber is pressed to about 51 mm to make it into a short fiber, and then put into a Soxhlet extractor, and n-hex The paraffin wax in the sheath was extracted by Sun to make the sheath porous.

The obtained composite textile had a strength of 2.2 g Zd and an elongation of 360 porosity of 259, and had good force properties.

Comparative Example 3

Instead of using the multi-spinning equipment, the raw material of the sheath part of Example 6 was used, and a 0.4-φ x 160-hole nozzle was attached to a single-screw spinning machine with a screw diameter of 25 mm. After spinning a 10-denier undrawn yarn at a nozzle temperature of 175 ° C., a porous fiber was obtained in the same manner as in Example 6, except that the drawing ratio was set to 3 times. The obtained fiber had a strength of 1.9 g d, an elongation of 450%, and a porosity of 2696.

The spinning conditions, physical properties, and the like of the above Examples and Comparative Examples are summarized in Table 1 below.

o

a: paraffin wax, p. ί): polypropylene, cardability: 〇: good, X: bad

Heat resistance test

Each of the fibers obtained in Examples 2 and 6 and Comparative Examples 1 and 3 was placed in an oven at 80 ° (: 1130) for 30 minutes, and the change in porosity before and after heating was measured. Table 2 below shows the measurement results.

(Table 2)

As is clear from the results shown in Table 2, it can be seen that the fibers of the examples are excellent in heat resistance because the solid core suppresses shrinkage, so that the porosity does not decrease due to ripening.

Further, in the force examples that can be seen from Table 1, the porosity is equal to or higher than that of the whole, despite the small content of paraffin wax. For example, Example 2 has a porosity of 48.8 <¾ with a paraffin wax of 40. Meanwhile Comparative Example 1 is a 5 0 ⁰ porosity 4 5 paraffin I Nwa click scan of. In other words, the sheath of Example 2 has a porosity of 61% '. The reason for this is considered as follows. In other words, the spinning temperature must be increased because a high-melting polypropylene component is added during spinning, and as a result, the porous sheath tends to cool more slowly. Spun in a lamellar crystal It is presumed that the length is promoted and the pore size increases.

On the other hand, in the case of Comparative Example 1, since the spinning is performed with a single PE porous portion, raising the nozzle temperature and performing the cooling conditions more slowly deteriorates the spinnability or deniers. It is not preferable because it causes an increase in unevenness. In addition, since the composite textile of Example 6 has high heat resistance, it is expected to be used as a liquid filter used in boiling water and can be subjected to high-temperature sterilization (130 ° C) using an autoclave. .

Industrial applicability

As described above, according to the composite curtain having the sheath according to the present invention, the strength is high, the card suitability is improved, and the heat resistance is also provided, so that a high-temperature liquid filter or high-temperature sterilization is possible. It can be used as a raw material for non-woven fabrics.

Claims

Range of request

(1) A sheath-core composite fiber comprising a sheath made of a polyolefin-based synthetic resin made porous and a nonporous core, wherein the apparent cross-sectional area of the sheath is a fiber A composite fiber having a porous sheath portion, having a cross-sectional area of 20 to 80%.

(2) The composite fiber having a porous sheath according to claim 1, wherein the polyolefin-based synthetic resin is high-density polyethylene.

(3) The composite fiber having a porous sheath according to claim 1, wherein the polyolefin-based synthetic resin is polypropylene.

(4) The first aspect of the present invention is characterized in that the porosification is performed by mixing paraffin wax with the polyolefin-based resin and removing the paraffin wax after spinning. Item 4. The composite fiber having a porous sheath portion according to any one of items 3 to 3.

(5) The composite fiber having a porous sheath portion according to any one of claims 1 to 3, wherein the core portion is a polypropylene resin.

(6) The composite fiber having a porous sheath portion according to any one of claims 1 to 3, wherein the core portion is a low melting point nylon resin.

(7) The composite fiber having a porous sheath according to any one of claims 1 to 3, wherein the core is a low-melting polyester resin.