JP2000017524A - Splittable composite fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a splittable conjugate fiber having excellent heat resistance and chemical resistance and having a single fiber denier of 1 dr or less, and a sheet-like material comprising the fiber. SOLUTION: At least two kinds selected from a thermoplastic polyamide component, a polyphenylene sulfide component, and polymethylpentene in which 60 to 100 mol% is composed of terephthalic acid units and 60 to 100 mol% is composed of fatty 1,9-nonanediamine units. Is a splittable conjugate fiber having a fiber cross-sectional shape in which the polymer of the above is bonded, wherein the single fiber denier after splitting is 1 dr or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a splitting device comprising at least two kinds of polymers selected from a specific semi-aromatic polyamide, polyphenylene sulfide and polymethylpentene, and having a single fiber denier of 1 dr or less after splitting. Type composite fiber. The splittable conjugate fiber of the present invention,
Excellent chemical resistance such as acid resistance, alkali resistance, organic solvent resistance, etc., and also excellent heat resistance. The woven or nonwoven sheet-like material using the splittable fiber has a very dense structure because the fiber is split to 1 dr or less, and is suitable for an air filter and a liquid filter. It can also be used as a wiper, heat-resistant insulating paper, separator, papermaking canvas, flame-retardant interior material, resin reinforcing material, and rubber reinforcing agent.

[0002]

2. Description of the Related Art As a filter having excellent chemical resistance, a filter using a lower polyolefin such as polypropylene or polyethylene has been widely used. Polyolefins are excellent in both acid resistance and alkali resistance, but have low heat resistance and cannot be used for applications used at high temperatures such as bag filters for collecting particles in soot and smoke. Therefore, in applications used at high temperatures, woven or nonwoven fabrics made of aramid such as polyparaphenylene terephthalamide or polymetaphenylene terephthalamide, or polyarylate having excellent heat resistance have been proposed as filters. However, aramid had insufficient acid resistance and polyarylate had insufficient alkali resistance. In order to solve the above problem, it has been proposed to use a woven or nonwoven sheet made of polymethylpentene or polyphenylene sulfide as a filter.

[0003]

A filter using a woven or nonwoven fabric made of polymethylpentene or polyphenylene sulfide has excellent chemical resistance and heat resistance. However, the monofilament denier of the fiber exceeded 1 dr, and the filter obtained was not dense, so that particles could not be collected on the surface and could not be repeatedly used after being washed off. In view of the above problems, an object of the present invention is to provide a splittable conjugate fiber having excellent heat resistance and chemical resistance, and a single fiber denier divided into 1 dr or less, and a sheet-like material comprising the fiber. It is in.

[0004]

That is, according to the present invention, 60 to 100 mol% of dicarboxylic acid units are composed of aromatic dicarboxylic acid units, and 60 to 100 mol% of diamine units.
Is a splittable composite fiber composed of at least two kinds of polymers selected from the group consisting of thermoplastic polyamides composed of aliphatic diamine units, polyphenylene sulfide and polymethylpentene, and each single fiber denier after division is 1 dr or less. It is a splittable conjugate fiber excellent in heat resistance and chemical resistance.

[0005] If a sheet-like material is prepared from the splittable conjugate fiber having such a structure and the splittable conjugate fiber is split, a dense sheet-like material made of ultrafine fibers having excellent heat resistance and chemical resistance can be provided. Can be.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. The thermoplastic polyamide used in the present invention substantially consists of dicarboxylic acid units and diamine units. As the dicarboxylic acid unit, terephthalic acid unit is 60 mol%
It is necessary that it be contained in an amount of at least 75 mol%, more preferably at least 90 mol%. Content of terephthalic acid unit is 6
When the amount is less than 0 mol%, various properties such as alkali resistance, acid resistance, and strength of the obtained fiber are undesirably reduced.

The dicarboxylic acid unit other than the terephthalic acid unit includes, for example, malonic acid, dimethylmalonic acid,
Succinic acid, 3,3-diethylsuccinic acid, glutaric acid,
Aliphatic dicarboxylic acids such as 2,2-dimethylglutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelic acid, azelaic acid, sebacic acid and suberic acid; 1,3-cyclopentanedicarboxylic acid; 4
Alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; isophthalic acid, 2,6-naphthalenedicarboxylic acid,
2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,4-phenylenedioxydiacetic acid,
1,3-phenylenedioxydiacetic acid, diphenic acid, 4,
4'-oxydibenzoic acid, diphenylmethane-4,4 '
One or more units derived from an aromatic dicarboxylic acid such as -dicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid, and 4,4'-biphenyldicarboxylic acid. From the viewpoint of chemical resistance, heat resistance, and the like, it is preferable to include an aromatic dicarboxylic acid unit among the above dicarboxylic acid units. Further, a polycarboxylic acid having three or more functional groups such as trimellitic acid, trimesic acid, and pyromellitic acid can be contained in a range where fiberization is possible.

The diamine unit must contain an aliphatic diamine unit in an amount of 60 mol% or more.
It is preferable to contain 5 mol% or more, and 90 mol%
More preferably, it is contained. When the content of the aliphatic diamine unit is less than 60 mol%, the resulting fiber has reduced acid resistance and strength.

The preferred diamine unit is 1,9
-Nonanediamine, but other diamine units other than the 1,9-nonanediamine unit include, for example, ethylenediamine, propylenediamine, 1,4-butanediamine, 1,6-hexanediamine, 1,8-octanediamine, , 10-decanediamine, 1,12-dodecanediamine, 2-methyl-1,5-pentanediamine, 3
-Methyl-1,5-pentanediamine, 2,2,4-trimethyl-1,6-hexanediamine, 2,4,4-trimethyl-1,6-hexanediamine, 2-methyl-
Aliphatic diamines such as 1,8-octanediamine and 5-methyl-1,9-nonanediamine; alicyclic diamines such as cyclohexanediamine, methylcyclohexanediamine and isophoronediamine; p-phenylenediamine;
m-phenylenediamine, xylylenediamine, xylenediamine, 4,4′-diaminodiphenylmethane,
One or more units derived from an aromatic diamine such as 4,4'-diaminodiphenylsulfone and 4,4'-diaminodiphenylether can be contained.

When the diamine unit contains a diamine unit other than the 1,9-nonanediamine unit, for example, the conjugate fiber of the present invention may be used for heat resistance, hydrolysis resistance, chemical resistance and the like of a battery separator or the like. In view of using the compound for applications in which is required, 2-methyl-1,8-octanediamine unit is preferred. And the diamine unit is a 1,9-nonanediamine unit and 2-methyl-
When 1,8-octanediamine unit is contained, 60 to 100 mol% of the diamine unit is composed of 1,9-nonanediamine unit and 2-methyl-1,8-octanediamine unit, and 1,9-nonanediamine unit. And the molar ratio of 2-methyl-1,8-octanediamine units is 40:
It is preferably 60 to 99: 1, and 70:30 to 9
More preferably, the ratio is 5: 5.

The method for producing a thermoplastic polyamide is not particularly limited, and any production method known as a method for producing a crystalline polyamide can be used. For example, polymerization can be performed by a solution polymerization method or an interfacial polymerization method using acid chloride and diamine as raw materials, a melt polymerization method using dicarboxylic acid and diamine as raw materials, a solid phase polymerization method, a melt extruder polymerization method, or the like.

The polyphenylene sulfide (sometimes abbreviated as PPS) used in the present invention includes a crosslinked type and a linear type. A cross-linked polyphenylene sulfide can be used, but it is preferable to use a linear type, since cross-linking may occur during yarn production. Further, if PPS is spun with a spinner of a usual material, the spinneret is severely damaged. Therefore, it is preferable to use a material having excellent corrosion resistance (for example, SUS420 hardened).

The polymethylpentene (PM) used in the present invention
P may be abbreviated as P) and poly-4 methylpentene-1 and a copolymer thereof. 4- as the copolymer
Methylpentene-1 and, for example, ethylene, propylene, butene-1, hexene-1, octene-1, decene-1,
One or more copolymers of tetradecene-1, octadecene-1 and the like.

The splitting property of the splittable conjugate fiber is affected by the adhesiveness caused by the difference in solubility parameter between the polymers or the swelling difference caused by the difference in the moisture absorption. For example, if the value of the solubility parameter is too close, the interface between the polymers will adhere, and it will not be possible to make a splittable conjugate fiber.
Conversely, if the difference between the solubility parameters is too large, the interface between the polymers is likely to peel off, and the fibers will be split, and when crimping or carding is performed to produce a nonwoven fabric, the processability will be poor. When a woven fabric is used, it is often divided into a woven fabric in a false twisting step after spinning. In this case, it is better to increase the difference in solubility parameter so that the woven fabric can be easily divided. A polymer may be selected in consideration of the value of the solubility parameter so as to have a necessary resolution according to the purpose of use. In the present invention, as a combination of the polymers to be composited, as long as there is no problem in the above-described division property, even a combination of polymers of the same kind, that is, a combination of thermoplastic polyamides having different chemical structures. It is not a problem.

The composite form in the fiber cross section of the splittable conjugate fiber composed of a combination of any two or more polymers of the thermoplastic polyamide, polyphenylene sulfide and polymethylpentene used in the present invention is a cross sectional form that can be split after yarn production. The fiber is not particularly limited as long as it is a fiber of the above type. For example, a laminated composite fiber in which the cross-sectional shape of a single fiber after division is wedge-shaped, plate-shaped (strip-shaped), or a combination thereof is used.

The splittable conjugate fiber of the present invention is used as an aggregate of ultrafine fibers having a single fiber denier of 1 dr or less by a splitting process. Since it is too thick, a dense sheet-like material cannot be formed, and particles cannot be collected on the filter surface and used after being removed.
Therefore, clogging occurs immediately and cannot be used continuously for a long time. Further, for example, a nonwoven fabric made of a single fiber exceeding 1 dr cannot obtain a sheet having sufficient texture and strength by needle punching or by hydroentanglement.

In the present invention, a fiber having excellent heat resistance means a fiber having a melting point of 220 ° C. or higher.
The melting point of the fiber can be easily known using, for example, DSC. Fibers having a melting point of less than 220 ° C. cannot be used due to insufficient heat resistance when used at a high temperature, for example, for collecting soot.

The chemical resistance in the present invention means alkali resistance, acid resistance, oxidation deterioration resistance, and solvent resistance. When the strength retention is 80% or more, it is suitable for use in industrial filters and wipers. Can withstand enough.

The form of the sheet obtained by dividing the splittable conjugate fiber of the present invention may be a woven fabric, a nonwoven fabric, or a combination thereof. In the case of producing a woven fabric as long fiber filaments, it may be woven by a method of producing an ordinary woven fabric using the split fibers by false twisting after the spinning. The weaving machine is not particularly limited. Manufacturing methods of nonwoven fabric using short fibers include those including carding and air lay called dry type and those including papermaking method called wet type.Either method is used to manufacture the sheet material of the present invention. Can be done. For forming a web of a dry short-fiber nonwoven fabric, a web can be formed using a roller card, a random card, a webber, or the like. The fibers in the web can be mechanically entangled by needle punching, water entanglement, or a combination thereof to form a fabric.However, when the splittable conjugate fibers are split in this entanglement step, a uniform sheet is formed. It is preferable because it is formed. After the papermaking, the fiber is split by hydroentanglement and the entangled sheet is
It is particularly preferable when making a thin filter because of good texture and high strength. The sheet entangled by needle punch or water entanglement can be used as it is, but it may be bonded by thermal bonding in order to increase the strength. In the case of bonding, if there is a difference in melting point between the polymers constituting the splittable conjugate fiber, the split fiber composed of a polymer having a low melting point may be used as a binder fiber, and may be thermally bonded using a calender, hot air, ultrasonic wave, or the like. Good.

[0020]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited thereto. In the following examples, the physical properties, chemical resistance, and the like of the splittable conjugate fiber and the sheet-like material were measured and evaluated by the following methods.

Melting point of fiber The endothermic peak was determined as the melting point by using DSC (Mettler: TA3000).・ Chemical resistance During the specified temperature and time in the specified chemical,
0 g of a wrapped fiber was immersed, the tenacity before and after the treatment was measured, and the retention (%) was evaluated. Resistance Acid resistance: · 10% HCl × 70 ℃ × 10h · 10% H 2 SO 4 × 70 ℃ × 100h Alkali resistance: · 10% NaOH × 70 ℃ × 60h · 28% NH 3 × 70 ℃ × 24h oxidation degradation Properties: 5% KMnO ₄ : 30% KOH = 250 cc: 50 cc, 50 ° C.
1 h Solvent resistance: Toluene × 90 ° C. × 1 hr Basis weight The obtained sample sheet was cut into a 10 cm square according to JIS P8124, and the weight W was measured with an electronic balance (Mettler: AE160). The basis weight (g / m ² ) was determined according to 0.01.・ Strength, tear length Sample sheet width 15 according to JIS P8113
The strength (kg / 15 cm) was measured using a test piece cut out to a length of 250 mm and a breaking length (km).

Example 1 Terephthalic acid (19.5 mol), 1,9-nonanediamine (10.0 mol), 2-methyl-1,8-ooctanediamine (10.0 mol), benzoic acid (1. 0 mol),
Sodium hypophosphite monohydrate (0.1% by weight based on the raw material) and 2.2 liters of distilled water were placed in an autoclave having an inner volume of 20 liters, and the atmosphere was replaced with nitrogen. The mixture was stirred at 100 ° C for 30 minutes, and the internal temperature was raised to 210 ° C over 2 hours. At this time, the pressure in the autoclave was increased to 22 kg / cm ² . After continuing the reaction for 1 hour, 230 ° C
Then, the temperature was maintained at 230 ° C. for 2 hours, and the reaction was carried out while gradually removing water vapor and maintaining the pressure at 22 kg / cm ² . Next, the pressure is increased to 10 kg / cm ² over 30 minutes.
, And reacted for another hour to obtain a prepolymer.
This was dried at 100 ° C. under reduced pressure for 12 hours and pulverized to a size of 2 mm or less. 230 ° C, 0.1mm
Polyamide (referred to as 9MT) was obtained by solid-phase polymerization under Hg for 10 hours. The obtained polyamide and polyphenylene sulfide (Toray: Fortron E24
81-50) is melt-extruded using two extruders,
Polyamide and polyphenylene sulfide were discharged at a weight ratio of 1: 1 from a composite nozzle of 0.2 mmφ × 24 holes, and an 11-division multilayer bonded composite fiber was spun. Subsequently, a water bath drawing treatment was performed at a drawing temperature of 95 ° C. and a draw ratio of 2.5 to obtain a tow of a splittable conjugate fiber having a single fiber denier of about 3 dr before splitting. Table 1 shows the physical properties and chemical resistance of the obtained fibers. FIG. 1 shows a schematic diagram of the cross-sectional shape of the obtained fiber.

[0023]

[Table 1]

Example 2 As raw materials for polyamide, terephthalic acid (19.4 mol), 1,9-nonanediamine (20.0 mol), benzoic acid (1.2 mol), sodium hypophosphite monohydrate A polyamide (referred to as 9T) was obtained in the same manner as in Example 1 except that (0.1% by weight based on the raw material) and 2.2 liters of distilled water were used. The obtained polyamide was spun at 340 ° C. in the same manner as in Example 1 to obtain a splittable conjugate fiber tow. Table 1 shows the physical properties and chemical resistance of the obtained fibers.

Example 3 As a raw material of polyamide, 2159.8 g of terephthalic acid was used.
(13.0 mol), 830.7 g of isophthalic acid (5.0
Mol), 292.3 g (2.0 mol) of adipic acid, 1,
Performed except that 2324.2 g (20.0 mol) of 6-hexanediamine, 24.43 g (0.2 mol) of benzoic acid, 6.5 g of sodium hypophosphite monohydrate, and 6 liters of distilled water were used. In the same manner as in Example 1, the polyamide (6
6IT). A tow of splittable conjugate fiber was obtained in the same manner as in Example 1 using the obtained polyamide. Table 1 shows the physical properties and chemical resistance of the obtained fibers.

Example 4 A splittable conjugate fiber was obtained in the same manner as in Example 2 except that the polyamide (9MT) used in Example 1 was used instead of the polyphenylene sulfide used in Example 2.
Table 1 shows the physical properties and chemical resistance of the obtained fibers.

Example 5 A splittable conjugate fiber was obtained in the same manner as in Example 1 except that polymethylpentene (Mitsui Chemicals: DX820) was used instead of the polyphenylene sulfide used in Example 1. Table 1 shows the physical properties and chemical resistance of the obtained fibers.

Example 6 A splittable conjugate fiber was obtained in the same manner as in Example 1 except that polymethylpentene (Mitsui Chemicals: DX820) was used instead of the polyamide used in Example 1. Table 1 shows the physical properties and chemical resistance of the obtained fibers.

COMPARATIVE EXAMPLE 1 Instead of the polyamide of Example 1, a commercially available polyamide comprising the same aliphatic (ε-caprolactam) having the same diamine unit and dicarboxylic acid unit (Ube Industries: UBE nylon 6, P
A6), and a splittable conjugate fiber was produced in the same manner as in Example 1. When the chemical resistance of the obtained fiber was examined, it was found that although the alkali resistance was excellent, the alkali resistance was low and insufficient (see Table 2).

[0030]

[Table 2]

Comparative Example 2 A commercially available polyamide (Ube Industries: UBE nylon) in which a diamine unit and a dicarboxylic acid unit consist of an aliphatic diamine (hexamethylenediamine) and an aliphatic dicarboxylic acid (adipic acid) instead of the polyamide of Example 1. 66, PA
66, and a splittable conjugate fiber was produced in the same manner as in Example 1. Although the obtained splittable conjugate fiber had excellent alkali resistance, the alkali resistance was low and insufficient (see Table 2).

Comparative Example 3 In place of the polyamide of Example 1, a commercially available polyamide (Mitsubishi Gas Chemical: MX) in which a diamine unit and a dicarboxylic acid unit consist of an aromatic diamine (metaxylylenediamine) and an aliphatic dicarboxylic acid (adipic acid) Nylon 6007,
MX) to produce splittable conjugate fibers in exactly the same manner as in Example 1. Although the obtained splittable conjugate fiber was excellent in alkali resistance, it had insufficient oxidation deterioration resistance and was insufficient (see Table 2).

Comparative Example 4 A splittable composite fiber was produced in exactly the same manner as in Example 1 except that polypropylene (Grand Polymer: Grand Polypro S106LA, referred to as PP) was used instead of the polyamide of Example 1. Although the obtained splittable conjugate fiber was excellent in chemical resistance, it had insufficient heat resistance and was insufficient (see Table 2).

Comparative Example 5 A splittable conjugate fiber was produced in exactly the same manner as in Example 1 except that polyethylene (Nippon Polychem: Novatec LD, LC500, PE) was used in place of the polyamide of Example 1. The obtained splittable conjugate fiber had insufficient toluene resistance and low heat resistance and was insufficient (see Table 2).

Comparative Example 6 A splittable conjugate fiber was prepared in exactly the same manner as in Example 1 except that a commercially available polyamide (Ube Industries: UBE nylon 6, PA6) was used in place of the polyphenylene sulfide of Example 1. Manufactured. Although the obtained splittable conjugate fiber was excellent in alkali resistance, it was insufficient in acid resistance and was insufficient (see Table 2).

Comparative Example 7 A splittable conjugate fiber was prepared in exactly the same manner as in Example 1 except that a commercially available polyamide (Ube Industries, Ltd .: UBE nylon 6, PA6) was used in place of the polyamide 9MT of Example 5. Manufactured. Although the obtained splittable conjugate fiber had excellent alkali resistance, it had poor acid resistance and was insufficient (see Table 2).

Examples 7 to 9 The tows obtained in Examples 1, 6 and 7 were crimped with a number of crimps of about 20/25 mm, cut into 51 mm and made into cotton. The cotton was formed into a web using a roller card, and entangled with a water to form a sheet having a basis weight of about 70 g / m ² . Table 3 shows the physical properties of the sheet.

[0038]

[Table 3]

Comparative Example 8 The polyamide (9MT) used in Example 1 was 0.2 mm ×
Spinning was performed at 310 ° C. using a 24-hole nozzle. Then, a water bath drawing treatment was performed at a drawing temperature of 95 ° C. and a draw ratio of 2.5 to obtain a tow of single fiber denier of about 3 dr. About 20 crimps / 25 mm of crimp were applied to the obtained tow, and 51
It was cut into mm and made into cotton. This cotton is made into a web using a roller card, entangled with water, and weighed about 70 g.
/ M ² . Table 3 shows the physical properties of the sheet.

Comparative Example 9 A sheet was obtained in the same manner as in Comparative Example 8 except that the polyphenylene sulfide used in Example 1 was used instead of the polyamide used in Comparative Example 8 (see Table 3).

Comparative Example 10 A sheet was obtained in the same manner as in Comparative Example 8 except that the polymethylpentene used in Example 5 was used instead of the polyamide used in Comparative Example 8 (see Table 3). Comparative Examples 8 to 1
Compared with the sheets of Examples 7 to 9, the sheet of No. 0 seems to have a larger diameter of the single fiber, but has not obtained sufficient strength due to insufficient entanglement due to entanglement.

Example 10 The cotton obtained in Example 7 was formed into a web shape using a roller card, and entangled with a needle punch to a weight of about 500 g.
/ M ^{2 in} the form of a sheet. Table 4 shows the physical properties of the sheet.

[0043]

[Table 4]

Example 11 The tow of single fiber denier 3dr before splitting obtained in Example 7 was cut into 5 mm to obtain cut fibers. The cut fiber was used to form a sheet by a wet method, and then subjected to splitting and entanglement by water entanglement to obtain a sheet having a basis weight of about 70 g / m ² . Table 4 shows the physical properties of the obtained sheet.

Example 12 A sheet was obtained in exactly the same manner as in Example 11, except that a composite nozzle having an orange cross-section was used instead of the composite nozzle of the lamination type used in Example 11. FIG. 2 shows a schematic diagram of the cross-sectional shape of the obtained fiber. Table 4 shows the physical properties of the obtained sheet.

[0046]

The present invention comprises at least two or more polymers selected from a specific semi-aromatic polyamide, polyphenylene sulfide and polymethylpentene,
Since the single fiber denier after splitting is a splittable conjugate fiber having a denier of 1 dr or less, it is excellent in chemical resistance such as acid resistance, alkali resistance and organic solvent resistance, and also excellent in heat resistance. The woven or non-woven fabric using the splittable fiber is divided into 1d
Since it is less than r, it can be used for a dense filter. It can also be used for wipers, separators, and papermaking canvases.

[Brief description of the drawings]

FIG. 1 is a schematic view of a fiber cross section of a splittable conjugate fiber produced in Example 1.

FIG. 2 is a schematic view of a fiber cross section of a splittable conjugate fiber manufactured in Example 12.

Claims (4)

[Claims] 1. 60 to 100 mol% of dicarboxylic acid units
Consists of aromatic dicarboxylic acid units, and 6 of diamine units
A splittable conjugate fiber composed of at least two polymers selected from the group consisting of thermoplastic polyamide, polyphenylene sulfide, and polymethylpentene in which 0 to 100 mol% is an aliphatic diamine unit; A splittable conjugate fiber excellent in heat resistance and chemical resistance, having a denier of 1 dr or less. 2. The thermoplastic polyamide has a dicarboxylic acid unit comprising a terephthalic acid unit and a diamine unit having a 1,9-diamine unit.
2. The splittable conjugate fiber according to claim 1, comprising a nonanediamine unit. 3. The thermoplastic polyamide, wherein the dicarboxylic acid unit comprises a terephthalic acid unit and the diamine unit comprises 1,9-
It is composed of nonanediamine units and 2-methyl-1,8-octanediamine units, and the molar ratio of 1,9-nonanediamine units to 2-methyl-1,8-octanediamine units is from 40:60 to 99: 1. Item 4. The splittable conjugate fiber according to Item 1. 4. A fibrous sheet comprising the splittable conjugate fiber according to claim 1, wherein at least a part of the fiber is split.