JPH1060760A - Thermoplastic fluororesin fiber fabric and short fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably obtain thermoplastic fluororesin fibers useful as a raw material for non-woven fabrics such as filters without corroding a spinneret by melt-spinning a vinylidene fluoride polymer having a specific melt flow value. SOLUTION: This thermoplastic fluororesin fiber fabric comprises melt-brown fibers comprising a vinylidene fluoride homopolymer or a thermoplastic fluororesin containing the vinylidene fluoride in an amount of >=60wt.% and having a melt-flow rate of 10-800g/10min, a flat raw material formed by a spun bond method or a flat raw material formed by the wet paper-making method of the short fibers. The fiber fabric is al-so formed from side-by-side type or sheath-core type conjugate fibers comprising the vinylidene fluoride homopolymer or the copolymer containing the vinylidene fluoride units in an amount of >=60wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic fluororesin short fiber and a fiber cloth. It is an object of the present invention to provide a fluororesin fiber cloth excellent in chemical resistance, antifouling property and the like, and a short fiber constituting the same.

[0002]

2. Description of the Related Art Thermoplastic fluorine-based resins such as polyvinylidene fluoride are excellent in weather resistance and chemical resistance, and are used as paints, electric / electronic parts, steel pipe linings, chemical plant parts, weather-resistant antifouling films, and the like. It is used for However, since it has little adhesiveness, there is a disadvantage that it is difficult to combine or modify with other materials.

In addition, the fibers have drawbacks such as difficulty in spinning and drawing from the viewpoint of viscosity and crystallinity, and low knot strength.

[0004] In order to improve these, for example, polymethyl methacrylate (PMMA) (JP-A-60-11091)
No. 2, JP-A-50-143848, etc.), isobutylene copolymer (JP-A-54-106622, etc.),
Acrylate (JP-B-60-17845, JP-A-57
JP-A-89611 and other blends of other fluororesins (Japanese Patent Publication No. 4-44012, JP-A-60-104514).
JP-A-55-84413, etc.), polyolefin (JP-A-62-268811, etc.), metal soap (JP-A-61-174418, etc.), fluorocarbon wax (Japanese Patent Laid-Open No. 60-115
652, etc.), or combinations thereof (Japanese Patent Application Laid-Open No. 6-101114, etc.), other special spinning and drawing methods (Japanese Patent Publication No. 53-22574, etc.), and the like. There are problems such as poor dispersibility and bleeding out due to the incorporation of components, and a decrease in strength and chemical resistance.
Not always enough.

[0005] In order to avoid such drawbacks, it has been proposed to use a polymer having physical properties in a specific range in combination without mixing other components. For example, molecular weight (Japanese Patent Publication No. 58-39922 and others), Haggins constant (Japanese Patent Application Laid-Open No. 60-59115 and others), melt viscosity (Japanese Patent Publication No.
No. 61087, etc.), head-to-head coupling (JP-A-60-59)
114, etc.), copolymerization ratio (JP-A-60-88123)
And the like, and a method of blending and spinning different polymers and fibers obtained therefrom.
Japanese Patent Publication No. 43-13399 discloses an intrinsic viscosity index (η
fibers having an inh) of 0.6 to 1.5,
No. 5359 discloses an intrinsic viscosity (ηinh) of 0.7-1.
Three are disclosed. However, in these publications, the notation and abbreviation in Japanese are different, it is unknown which is correct, and there are mixed properties that define physical properties such as solution viscosity, melt viscosity, MFR related to the molecular weight of the polymer. , It is difficult to grasp the mutual relationship. In any case, however, these are mainly concerned with monofilaments and long fibers (multifilaments), and there is little suggestion regarding short fibers (staple fibers).

[0006]

In the case of short fibers, or in the case of spinning by melt-blowing or spunbonding, in which a large amount of fibers are spun at a high speed, unlike monofilaments and long fibers, once from many adjacent spinning holes. Since it is necessary to spin a large amount of the molten polymer, the melting characteristics of the polymer, particularly the melt viscosity and the stability of the melt heat, are important. The present invention is intended to improve the spinnability and performance of fluororesin staple fibers, and to provide a thermoplastic fluororesin staple fiber and a fiber cloth without adding other substances.

[0007]

The present invention comprises a thermoplastic fluororesin containing at least 60% by weight of vinylidene fluoride as a constituent unit, and has a melt flow rate (23).
0 ° C, MFR under 2.16 kg load) 10 to 800 g
/ 10 minutes.

The thermoplastic fluororesin used in the present invention is a thermoplastic fluororesin containing 60% by weight or more, preferably 80% by weight or more, more preferably 90% by weight or more of vinylidene fluoride as a constituent unit. . Therefore, the copolymer is not limited to a homopolymer composed of one kind of monomer. Even if it is a copolymer containing other components in a range of 40% by weight or less as long as the properties of the thermoplastic fluororesin are not impaired, May be a mixture of the above polymers. Examples of the copolymerizable monomer include ethylene tetrafluoride, propylene hexafluoride, ethylene trifluoride, ethylene trifluoride chloride, vinyl fluoride, ethylene, and perfluoroalkyl vinyl ether.
Species or two or more species can be used. The thermoplastic fluororesin is obtained by a commonly used polymerization method such as emulsion polymerization and suspension polymerization, and its MFR value (230
° C, melt flow rate at 2.16 kg load)
Should be 10 to 800 g / 10 min.
If the MFR is less than 10, the spinning temperature must be set high, which is problematic in terms of thermal stability and mass productivity. Conversely, if it exceeds 800, droplet breakage tends to occur, and spinning stability is lacking.

In addition, the optimum MF of thermoplastic fluororesin
The R value differs slightly depending on the spinning process used, and the MFR value is preferably 30 to 800 g / 10 min in the case of the melt blow method, and 10 to 300 g / 10 min in the case of the spun bond method.

[0010] In the case of short fibers, the fibers of the present invention can be obtained by spinning, drawing, heat-treating and crimping if necessary by a conventional melt spinning method, and then cutting to a required length. In the case of melt blowing, a molten polymer is blown from a spinneret by a heated and compressed gas, and spun bonding is generally performed by a known method. These spinning temperatures are from 180 to 290C, preferably from 200 to 270C. When the temperature exceeds the upper limit, the polymer is decomposed, or the degraded polymer remaining in the dead space of the spinning machine or the polymer conduit not only deteriorates the fiber quality but also deteriorates the spinning process. If the temperature is lower than the lower limit temperature, not only the polymer is insufficiently melted or spinning is difficult due to the high viscosity, but also only fibers of poor quality are obtained due to the heat generated by the resin.

In the present invention, the fibers constituting the fiber cloth may have an irregular cross section or a hollow fiber in addition to the usual solid round cross section. Further, a composite fiber comprising a vinylidene fluoride homopolymer and a copolymer containing vinylidene fluoride units in an amount of 60% by weight or more may be used. Representative examples of such composite fibers include side / by / side type composite fibers and core / sheath type composite fibers.

In the case of melt blowing or spun bonding, a method of producing a fiber cloth from fibers is obtained by directly spinning the fibers onto a conveyor belt and, in some cases, press-bonding the fibers by a heat roller or the like. In the case of short fibers, the fibers can be entangled with each other by a wet papermaking method and made into a flat material to obtain a fiber cloth.

The fiber of the present invention contains a conventionally known antioxidant,
Thermal decomposition inhibitor, UV absorber, hydrolysis resistance improver, coloring agent (dye, pigment), antistatic agent, conductive agent, crystal nucleating agent, crystallization accelerator, plasticizer, lubricating agent, lubricant, release agent ,Flame retardants,
A flame retardant aid, a reinforcing agent, a filler, an adhesion aid, a pressure-sensitive adhesive, and the like can be arbitrarily contained.

[0014]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but it goes without saying that the present invention is not limited to these examples. The melt flow rate (MFR) of the thermoplastic fluororesin is 2 in accordance with ISO1133.
It is a value measured at 30 ° C. under a load of 2.16 kg. (Unit g / 10 minutes)

[0015]

Example 1 A vinylidene fluoride homopolymer having an MFR value of 33 g / 10 min was fed to a 32 mm single screw extruder equipped with a mouthpiece having ten 0.5 mmφ holes at the tip.
Spinning was performed at 260 ° C. to obtain a fiber of 150 de / 10 fill. Spinning was completed without any trouble during this time. Ten undrawn yarns are bundled to a total of 1500 de, stretched 3.2 times in hot water at 90 ° C., then crimped by mechanical buckling while running continuously, and further heated in hot air at 120 ° C. , And cut into 8 mm with a cutter to obtain cotton-like short fibers. The physical properties of the staple fiber are as follows: strength 3.2 g / de, elongation 16
It was 0%. After dispersing the short fibers in water, papermaking was performed using a papermaking canvas to obtain a flat fiber cloth having a basis weight of 50 g / m2. When a drop of water is dropped on this fiber cloth, 1
Water droplets did not disappear even after 0 minutes, indicating excellent water repellency.

[0016]

Comparative Example 1 A vinylidene fluoride homopolymer having an MFR value of 0.3 g / 10 min was used in the same manner as in Example 1 to obtain a 15
Attempting to spin a 0de / 10fil yarn,
At ℃, the viscosity was high, and the yarn was frequently broken, and a satisfactory yarn could not be drawn. When the temperature was raised to 300 ° C., a continuous thread came out of the die, but the droplet was broken and could not be wound up properly. After spinning for 4 hours, the spinneret was inspected, and a slight trace of corrosion was observed.

[0017]

Example 2 and Comparative Example 2 The same single screw extruder as in Example 1 was used.
A base with 100 holes of 0.3 mmφ arranged in a row, and a coat hanger type spinning head with a width of 100 mm with slits for hot air blowing of 0.5 mm on both sides are attached, and a vinylidene fluoride homopolymer having an MFR of 66 Was extruded at 255 ° C., and the compressed air heated to 280 ° C. was blown out from the slits on both sides and collected on a screen-shaped conveyor belt to obtain a fiber cloth having a basis weight of 60 g / m 2.
The simple test of dropping water showed excellent water repellency. When melt blown similarly using a vinylidene fluoride homopolymer of MFR4 for comparison, the blowing of the molten polymer was non-uniform, and a satisfactory fiber cloth was not obtained. In addition, a simple test of dropping water droplets showed that water droplets on the fiber cloth tended to slightly bleed in 5 minutes.

[0018]

Example 3 Vinylidene fluoride homopolymer having an MFR of 150 g / 10 min, 23% of ethylene tetrafluoride, 15% of propylene hexafluoride, and 62% of vinylidene fluoride
% Of a terpolymer having a copolymerization ratio of MFR of 380 g / 10 min and a spunbond process using a circular nozzle to obtain a web composed of a core / sheath type composite fiber having a vinylidene fluoride homopolymer core and a terpolymer sheath. . The resin temperature for spinning was 250 ° C. The spinning was smooth and no trouble occurred even after 3 hours. When the web was thermocompressed through a 130 ° C. heat roller, a good nonwoven sheet was obtained.

[0019]

As described above, the fiber cloth and staple fiber of the present invention can be spun stably without corrosion of the die due to the appropriate viscosity of the polymer, and the obtained fiber cloth has excellent water repellency. It is useful as a nonwoven fabric material for filters and the like.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location D21H 13/12 D21H 5 / 20F (72) Inventor Takatoshi Kuratsuji Nakadoji Temple, Shimogyo-ku, Kyoto-shi, Kyoto 1 Awatacho Elf Atochem Japan Co., Ltd. Kyoto Technical Center

Claims (7)

[Claims] 1. Vinylidene fluoride as a constituent unit
A fiber cloth comprising a thermoplastic fluorine-based resin containing at least 10% by weight and having a melt flow rate (MFR at 230 ° C. under a load of 2.16 kg) of 10 to 800 g / 10 minutes. 2. The fiber cloth according to claim 1, wherein the fiber cloth is made of thermoplastic fluororesin short fibers. 3. The fiber cloth according to claim 1, wherein the fiber cloth is a melt blown fiber of a thermoplastic fluororesin or a planar material formed by a spun bond method. 4. Vinylidene fluoride as a constituent unit in 60
A short fiber comprising a thermoplastic fluororesin containing at least 10% by weight and having a melt flow rate (MFR at 230 ° C. under a load of 2.16 kg) of 10 to 800 g / 10 minutes. 5. A fiber according to claim 1, wherein the fiber constituting the fiber cloth is a composite fiber comprising vinylidene fluoride homopolymer and a copolymer containing vinylidene fluoride units in an amount of 60% by weight or more. A fiber cloth according to any one of claims 3 to 3. 6. The fiber cloth according to claim 5, wherein the conjugate fiber is a side / by / side type conjugate fiber. 7. The fiber cloth according to claim 5, wherein the composite fiber is a core / sheath type composite fiber.