JP2577153B2 - Sulfonated polyolefin fiber and fiber assembly thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sulfonated polyolefin fiber and an assembly using the fiber. More specifically, the present invention relates to a fiber containing a methylpentene-based polymer having excellent hydrophilicity and an aggregate using the fiber.

[0002]

2. Description of the Related Art Hitherto, polyolefin fibers are chemically stable fibers, and their use has been widely and generally used as nonwoven fabrics. When forming into a nonwoven fabric, it is also common to use a low-melting-point component excellent in thermal adhesion as an adhesive fiber for bonding fibers to each other. That is, it is used as a core-sheath type conjugate fiber (conjugate fiber) using polypropylene as a core component and a low melting point component such as polyethylene as a sheath component. However, such composite fibers are generally poor in hydrophilicity, and there is a limitation in developing them into applications such as fibers for separators of rechargeable batteries or storage batteries or fibers for cement reinforcement. For example, a separator for an alkaline battery is disclosed in
No. 7956, No. 58-194255 and No. 61-39362, a polyolefin nonwoven fabric treated with a surfactant to enhance hydrophilicity, and a polyamide having low oxidation resistance but good hydrophilicity Nonwoven fabrics mainly composed of fibers have been proposed. JP-A-58-145
Japanese Patent No. 705 discloses a method of making a polymer hydrophilic by sulfonation.
Polyolefin fibers have been proposed.

However, the nonwoven fabric for an alkaline battery separator is required to be made of an alkali-resistant material for a strong alkaline electrolyte and to have an antioxidant property against electrolytic oxygen generated during charging.
Furthermore, a high specific volume is required to maintain the penetration and wetting of the electrolyte. In addition, it must have morphological stability such that the electrodes are not short-circuited due to dielectric breakdown due to deterioration, shrinkage or dissolution during use, and appropriate mechanical strength for assembly work. From such a point, the polyamide fiber does not have sufficient alkali resistance and oxidation resistance, and does not have sufficient form stability.

For this reason, attempts have been made to use polyolefin fibers after they have been treated with a surfactant. However, the drawback is that the surfactant is eluted by a large number of charge / discharge cycles, and the hydrophilicity gradually deteriorates. is there. In order to solve these problems, the use of ethylene-vinyl alcohol copolymer fibers described in JP-A-63-34849, JP-A-58-175256, JP-A-64-57568, and Japanese Unexamined Patent Publication No. 1-132043 and Japanese Patent Application Laid-Open No.
Publication, EPC Publication No. 0316916A2 (198
It has been proposed to use those obtained by sulfonating polyethylene fibers or polypropylene fibers found in 9.5.24). JP-A-3-279452
Publication No. 2 contains polyethylene fibers and polypropylene fibers.
And composite fibers of polyethylene and polypropylene.
Woven fabrics have been proposed.

[0005]

However, Japanese Patent Application Laid-Open Nos. 63-34849 and 58-175256 describe the above-mentioned problems.
JP-A-64-57568, JP-A-1-13204
No. 3, JP-A-1-132044, and EPC Publication No. 0316916A2, in which a poly (α-olefin) such as polyethylene or polypropylene is subjected to a sulfonation treatment with fuming sulfuric acid or the like, and a hydrogen substitution reaction of tertiary carbon is performed. Therefore, the reaction rate is poor and there is a problem in the manufacturing process. In addition, sulfone groups cannot be efficiently introduced, and it is difficult to control the reaction rate. Also JP
Polyolefin proposed in JP-A-58-145705
The fiber is made of poly (α-olefin) or a copolymer thereof.
It is a single fiber of the body.
However, there was a problem that the curing and the strength of the resin decreased. JP-A-3-2
The nonwoven fabric proposed in JP 79452 increases strength.
The main focus is on the characteristics such as hydrophilicity.
Had not been considered.

In order to solve the above-mentioned problems of the prior art, the present invention provides a fiber containing a methylpentene-based polymer which can be easily sulfonated with hot concentrated sulfuric acid and has excellent alkali resistance and hydrophilicity, and an aggregate thereof. The purpose is to provide.

[0007]

In order to achieve the above object, the sulfonated polyolefin fiber of the present invention comprises poly (4-methylpentene-1) or a copolymer of 4-methylpentene-1 and another α-olefin. Components consisting of a methylpentene polymer composed of a polymer and poly (α-olefin)
A composite fiber according to the methylpentene polymer forms more than 40% of the fiber surface, and a structure that at least a part sulfone group in the structural unit of the methylpentene polymer is introduced It is a thing.

In the above construction, the fiber cross-section structure
And the poly (α-olefin)
Are present next to each other, and both components
It is preferable that a part thereof forms a fiber surface .

In the above structure, it is preferable that the fiber is a core-sheath composite fiber, the sheath component is a methylpentene polymer, and the core component is poly (α-olefin) .

Next, the fiber assembly of the present invention comprises a poly (4-methylpentene-1) or a methylpentene-based polymer comprising a copolymer of 4-methylpentene-1 and another α-olefin and poly (α -olefin). -Olefin).
Synthetic fiber, wherein the methylpentene polymer is 40
% Or more of the sulfonated polyolefin fibers forming a fiber surface and having a sulfone group introduced into at least a part of the structural units of the methylpentene polymer.
A composition in which polyolefin having a melting point of less than 140 ° C. is used as a heat bonding component, and 40 to 0% by weight of a heat bonding fiber containing polypropylene as a fiber forming component is a component, and the whole is melt bonded and integrated. It is provided with.

[0011]

According to the constitution of the present invention, since the methylpentene-based polymer forms a fiber surface of 40% or more and a sulfone group is introduced into at least a part of the constitutional unit, alkali resistance and hydrophilicity are improved. And a fiber assembly using the same. That is, it can be easily sulfonated with hot concentrated sulfuric acid. This is because methylpentene-based polymers are other poly (α-olefins such as polypropylene and polybutene-1 ).
Since the side chain is longer than the emission) in polypropylene in nobler mild sulfonation conditions, it is estimated that easy to introduce its backbone tertiary sulfone group to a carbon of the (-SO ₃ H). The methylpentene-based polymer used in the present invention preferably has a melting point of 210 to 245 ° C, and when the fiber is composed of only a polyolefin, it has excellent acid resistance and alkali resistance.

The fiber is a splittable conjugate fiber, and methyl pen
Ten-based polymer and poly (α-olefin) break fiber
Divided to be adjacent to each other in the surface structure
Some of the divided components form the fiber surface.
According to the preferred configuration of the present invention,
(Α-olefin) is more soluble than methylpentene polymer.
Because it is difficult to be converted to rufone, it changes in various properties such as strength as a fiber.
There is an effect that the operation in the post-process is easy without any modification.

According to a preferred configuration of the present invention in which the fiber is a core-sheath composite fiber, the sheath component is a methylpentene polymer, and the core component is polypropylene, the sheath portion of the fiber surface layer By exhibiting alkali resistance and hydrophilicity, the core portion of the fiber can have strength and shape retention.

Next, according to the structure of the fiber assembly of the present invention,
Because of the following constitutions (A) to (C), a heat-bonded nonwoven fabric having excellent alkali resistance and hydrophilicity can be obtained. (A) Methylpentene polymer and poly (α-olefin)
), Wherein the methylpentene-based polymer forms a fiber surface of 40% or more and a sulfone group is introduced into at least a part of the structural units of the methylpentene-based polymer. (C) 40 to 0% by weight of a heat-bonding fiber containing 60 to 100% by weight of a sulfonated polyolefin fiber and (B) a polyolefin having a melting point of less than 140 ° C. as a heat-bonding component and polypropylene as a fiber-forming component. ) The whole is melt bonded and integrated.

[0015]

The present invention will be described more specifically with reference to the following examples. The methylpentene polymer used in the present invention preferably has a melting point in the range of 210 to 245 ° C. Further, when the methylpentene polymer is exposed on the surface of 40% or more of the fibers, the hydrophilicity becomes excellent when sulfonated. The sulfonation treatment can be performed by immersion in hot concentrated sulfuric acid. This sulfone group introduction reaction is considered to proceed as shown in the following formula ( Formula 1).

[0016]

Embedded image

The above formula (1) represents one unit of the polymer. As shown in the above (Chemical formula 1), a sulfone group is easily introduced into at least a part of the tertiary carbon to which the side chain of the methylpentene unit is bonded. The introduction ratio of the sulfone group is from 0.01 to 0.01 in the methylpentene unit.
About 5 mol% is preferable.

The sulfonation treatment may be performed at the fiber stage, but is preferably performed after forming the nonwoven fabric. This is because it is easy to process. As the polyolefin fiber to be sulfonated according to the present invention, a homopolymer of 4-methyl-1-pentene and a copolymer of 4-methyl-1-pentene and another α-olefin can be used. In the present invention, these polymers are collectively referred to as “methylpentene polymers”. Other α-olefins copolymerized with 4-methyl-1-pentene include, for example, ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 3-methyl-1- Α-olefins such as pentene, 3-ethyl-1-pentene and 3-ethyl-1-hexene can be mentioned.

Next, a cross section of a conjugated composite fiber which is preferable as an example of the present invention is as shown in FIGS. 1 to 3, 1 is a conjugated composite fiber, 2 is a sulfonated methylpentene-based polymer,
3 is another poly (alpha-O olefins). The poly (alpha-olefins) such as polyethylene, polypropylene, poly (1-butene), Po Li (3-methyl-1
Etc. butene) can be mentioned.

When a core-sheath composite fiber is used, the core component is
Polypropylene is most preferable, and polyethylene having a melting point of 120 ° C. or more, an ethylene-propylene copolymer, a copolymer of ethylene and ethylene carboxylic acid, and the like can be used in order to perform sulfonation treatment with hot concentrated sulfuric acid or the like.

Next, a production example of the fiber or fiber aggregate of the present invention will be described. It is composed of 4-methylpentene-1 having heat stretchability and another α-polyolefin, and has a melting point of 210 to 24.
The melt flow rate (MFR) at a measurement temperature of 250 to 350 ° C. is 30 to 2 at a weight of 2169 g.
Fibers having a methylpentene copolymer having a fiber surface of 00 g / 10 minutes can be melt-spun at a temperature of 250 to 350 ° C. Thereafter, the fiber was hot-drawn by a factor of 2 or more, and the fiber strength and elongation were significantly improved compared to the undrawn yarn.
繊 維 30 denier fiber. This fiber can be directly sulfonated for use in a fibrous form such as a fiber for reinforcing cement for steam curing with improved cement affinity. Non-woven fabrics such as battery separators, and fiber compositions such as felt are used in hot roll processing such as spunlace processing or spot embossing processing in which fibers are entangled with pressurized water. Temperature (° C.) × sulfuric acid concentration (weight ratio of sulfuric acid) exceeds 50, and immersed in hot concentrated sulfuric acid of 60 ° C. or higher and lower than 110 ° C. to sulfonate and hydrophilize at least the methylpentene copolymer on the fiber surface. Thus, the hydrophilic polyolefin fiber of the present invention or its fiber composition can be obtained. Of course, Japanese Patent Application Laid-Open No.
It is also possible to use a conventional technique for sulfonating a polyolefin as described in JP-A No. 2 (1994), for example, a treatment method using fuming sulfuric acid, sulfur trioxide gas, chlorosulfonic acid or the like. In addition, since methylpentene copolymer is inherently water-repellent and hydrophobic like a fluororesin such as polytetrafluoroethylene, the methylpentene copolymer exposed on the fiber surface is somewhat sulfonated, but exhibits hydrophilicity. In the case of the conjugate fiber, if the methylpentene copolymer exposed on the fiber surface is sufficiently sulfonated and shows hydrophilicity, the exposed methylpentene copolymer preferably occupies at least 40% of the surface. % Is most preferred. The polyolefin fiber of the present invention refers to a fiber constituting a short cut fiber for paper, a staple fiber, a multifilament fiber, a spun bond nonwoven fabric and a melt blown nonwoven fabric. The fiber composition of the present invention refers to, for example, a nonwoven fabric, paper, felt, a spun yarn, a spun yarn, and a woven or knitted fabric composed of a multifilament yarn. Hereinafter, specific examples will be described.

Examples 1-4 Melt flow rate 50 g / 10 min (weight 2169 g,
270 ° C.), and a methylpentene copolymer (PMP, product “DX-820” manufactured by Mitsui Petrochemical Co., Ltd.) having a melting point of 240 ° C. is used as a sheath component (A component)) 2 and a melt flow rate of 20 g /
A polypropylene (PP) having a melting point of 163 ° C. and a core component (B component) of 3 for 10 minutes (weight 2169 g, 230 ° C.) is shown in FIGS. 1 to 3 in which the composite ratio (cross-sectional area ratio of each component) is 50:50. Core-sheath type composite fiber 1 or split type composite fiber 1 having fiber cross section
Is melt-spun and stretched 4 times using a hot roll at 140 ° C. in an atmosphere at 140 ° C., and after applying a fiber treatment agent, crimping is applied using a stuffing box. It was dried with a penetrating dryer and cut into 51 mm to form staples. Using a roller card as a web,
Using a spot-bonded hot roll at 165 ° C., a thermocompression-bonded nonwoven fabric is immersed in 90 ° C., 92% hot concentrated sulfuric acid for 30 minutes, then immersed in dilute sulfuric acid, washed with a large amount of water, and dried, followed by drying. A nonwoven fabric as a fiber composition was obtained. When these nonwoven fabrics were gently floated in water, Examples 1 and 2 immediately submerged in water ( submergence: 、 ), and Examples 3 and 4 submerged when pushed into water with a finger (submergence: △) .

Comparative Example 1 A diagram similar to that of Example 1 was used, except that the polymer component was changed.
It created a composite fiber cross-sectional shape shown in 4. The polymer component has a melt index of 6 g / 10 min (weight: 2169)
g, 190 ° C.), high-density polyethylene (HDPE) having a melting point of 126 ° C. as a sheath component 12, and a melt flow rate of 2
0 g / 10 min (weight 2169 g, 230 ° C), melting point 16
Composite fiber 11 was obtained in the same manner as in Example 1 except that polypropylene (PP) at 3 ° C. was used as core component 13. Next, the fiber was stretched 3.8 times in warm water at 80 ° C., applied with a fiber treatment agent, crimped using a stuffing box, and dried at 105 ° C. to obtain 51 mm staples. Then, a spot-bonded heat-bonded nonwoven fabric was prepared at 130 to 150 ° C. in the same manner as in Example 1, and sulfonated. The resulting sulfonated heat-bonded nonwoven fabric floated and did not submerge when pushed into water ( submersibility: X).

Comparative Example 2 A melt flow rate of 20 g / 1 as a core component of Comparative Example 1
It was melt-spun with a single PP of melting point 163 ° C. for 0 minutes.
These were stretched 3.8 times in hot water at 80 ° C., applied with a fiber treatment agent, crimped using a stuffing box, and dried at 105 ° C. to obtain 51 mm staples. Then, a spot-bonded heat-bonded nonwoven fabric was prepared at 130 to 150 ° C. and sulfonated in the same manner as in Example 1.
As in Comparative Example 1, even when pushed into water, it floated and did not submerge ( submersibility: X).

Examples 5 to 8 A fiber treatment agent was applied to the drawn yarns of Examples 1 to 4 to produce a tow.
And sulfonated in the same manner as in Example 1.
The affinity was exactly the same as that of Examples 1-4.

Conditions of Examples 1 to 8 and Comparative Examples 1 and 2
And the results are summarized in Table 1.

[0027]

[Table 1]

In Table 1, PMP is methylpentene.
Polymer, PP is polypropylene, HDPE is high density
The degree of polyethylene is shown. Table 1
The hydrophilicity of the fibers or heat-bonded nonwoven fabrics of Examples 1 to 8 is
It was excellent. Further, the fibers of Examples 1 to 8 or
The heat-bonded nonwoven fabric had excellent alkali resistance.

As described above, the fibers and fiber aggregates of the present embodiment have the following features. Excellent heat and alkali resistance. The melting point exceeds 200 ° C., but thermocompression bonding can be performed at 165 ° C. or higher. Sulfonation is easy with hot sulfuric acid, and good hydrophilicity can be imparted by sulfonation. It is useful as a separator for a rechargeable battery that requires strong heat-resistant alkalinity and hydrophilicity. Battery separators that require acid resistance and hydrophilicity,
It is also suitable as a hydrophilic nonwoven fabric for producing acids and alkalis. It is also suitable as a fiber for reinforcing cement for steam curing, which requires heat-resistant alkali resistance, hydrophilicity and cement affinity.

[0030]

According to the polyolefin fiber and the fiber composition of the present invention, the fiber is composed of polyolefin, and at least a part of the fiber surface is occupied by a sulfonated methylpentene polymer which has been hydrophilized by sulfonation treatment. Excellent in acid resistance, alkali resistance and hydrophilicity. For this reason, it was difficult to apply conventional water-repellent and hydrophobic polyolefin fibers to battery separators, filter cloths and cement reinforcing fibers, etc.
It can be conveniently used in fields requiring both alkali resistance.

[Brief description of the drawings]

FIG. 1 is a fiber sectional view showing one embodiment of a polyolefin fiber of the present invention.

FIG. 2 is a fiber sectional view showing another embodiment of the polyolefin fiber of the present invention.

FIG. 3 is a fiber sectional view showing another embodiment of the polyolefin fiber of the present invention.

4 is a fiber cross-sectional view of a fiber used in a ratio Comparative Examples.

[Explanation of symbols]

Reference Signs List 1 composite fiber 2 methylpentene-based polymer (component A) 3 α-polyolefin (component B ) 11 composite fiber 12 sheath component 13 core component

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location D06M 11/55 D06M 11/02 (72) Inventor Yoshiharu Usui 877 Komiya, Harimacho, Kako-gun, Hyogo Die (72) Inventor: Yosuke Takai, 877, Komiya, Harima-cho, Kako-gun, Hyogo Dai: Within Harima Research Laboratory, Wabobo Create Co., Ltd. (56) References: JP-A-58-145705 (JP, A) JP-A-3-279452 (JP, A)

Claims (4)

(57) [Claims] 1. A poly (α-O -olefin) comprising a poly (4-methylpentene-1) or a methylpentene-based polymer comprising a copolymer of 4-methylpentene-1 and another α-olefin.
And a component thereof, wherein the methylpentene-based polymer forms a fiber surface of 40% or more, and a sulfone group is introduced into at least a part of the structural units of the methylpentene-based polymer. Is a sulfonated polyolefin fiber. 2. The method according to claim 1 , wherein the methylpentene
Polymer and poly (α-olefin) are next to each other
Exist to fit together, some of which are part of the fiber surface
The sulfonated polyolefin fiber according to claim 1, which forms: 3. The fiber according to claim 1, wherein the fiber is a core-sheath composite fiber.
Sheath component is methylpentene polymer, the core component Po
The sulfonated polyolefin fiber according to claim 1, wherein the fiber is poly (α-olefin) . 4. A poly (α-O -methylpentene-1) or a methylpentene-based polymer comprising a copolymer of 4-methylpentene-1 and another α-olefin and poly (α-o -pentene-1).
And the methylpentene-based polymer forms a fiber surface of 40% or more,
60 to 100% by weight of a sulfonated polyolefin fiber having a sulfone group introduced into at least a part of the structural unit of the methylpentene polymer;
A sulfonated polyolefin fiber aggregate in which a polyolefin having a temperature of less than 40 ° C. is used as a heat bonding component, and 40 to 0% by weight of a heat bonding fiber containing polypropylene as a fiber forming component is a component, and the whole is melt-bonded and integrated.