JP2007039843A - Spun yarn of thermoplastic fiber-mixed oxidized fiber and method for producing woven fabric of oxidized fiber and woven fabric of carbon fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spun yarn of a thermoplastic fiber-mixed oxidized fiber having high strength, excellent in spinning properties in a spinning process and excellent in woven fabric-processing properties in a weaving process. <P>SOLUTION: In the spun yarn in which an oxidized fiber is mixed with a thermoplastic fiber and the mixture is spun, carbonization yield of the thermoplastic fiber is 0.5 mass% and fineness of the thermoplastic fiber is 0.5-10.0 dtex and fineness of the oxidized fiber is 0.5-3.4 dtex and mixing ratio of the thermoplastic fiber in the spun yarn is 7-45 mass% and dry strength of the spun yarn is ≥16 mN/dtex and twist count of the spun yarn is 150-900 times/m. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a carbon fiber fabric with less surface fluff, an oxidized fiber spun yarn for producing the carbon fiber fabric, and a method for producing an oxidized fiber fabric.

  Oxidized fiber has infusibility and flame retardancy, and is carbonized in a high-temperature inert gas atmosphere as needed, and applied to various applications such as heat insulating materials, non-combustible materials, conductive materials, and reinforcing materials. Yes. In particular, carbonized fibers (carbon fibers) are attracting attention as electrode materials that can utilize the characteristics of the fiber form such as flexibility, processability, and moldability, and are applied to polymer electrolyte fuel cells.

  As the carbon fiber material used for the electrode material of the polymer electrolyte fuel cell, there is a great demand for a carbon fiber material having a particularly thin sheet shape, strength, low electrical resistance, and flexibility, and various carbon fibers. A structure has been developed.

  Carbon fiber structures for polymer electrolyte fuel cells include (1) C / C paper (sheet-like carbon fiber reinforced carbon material), (2) carbon fiber nonwoven fabric, (3) carbon fiber filament fabric, and (4) Carbon fiber spun yarn fabric and the like are exemplified.

  Among these structures, carbon fiber spun yarn fabric is more flexible than C / C paper. Higher strength than carbon fiber nonwoven fabric. Compared to carbon fiber filaments, they are bulky and have a high degree of fiber alignment in the thickness direction, so they have excellent gas permeability and electrical conductivity.

In addition to making use of these characteristics, further problem improvement has been studied (see, for example, Patent Documents 1 and 2). In particular, Patent Document 2 has studied the reduction in the amount of surface fluff and has achieved some improvement. However, despite the examination in Patent Document 2, it cannot be said that the amount of surface fluff generation is sufficiently reduced, and further improvement is necessary.
JP 2002-348743 A (claims, paragraph numbers [0096] to [0111]) JP 2003-109616 A (Claims, paragraph numbers [0089] to [0102])

  While the present inventor has made various studies in order to solve the above problems, the oxidized fiber, which is a raw material for producing a carbon fiber fabric, is a fiber compared to a general thermoplastic fiber (nylon, polyester, polyolefin, etc.). It was considered that the above problems were caused by low strength and elongation and inferior spinning workability.

  General organic fibers / thermoplastic fibers are excellent in fiber characteristics, but burn and burn out in a high temperature atmosphere in the atmosphere. However, in an inert atmosphere, it melts and decomposes at a high temperature and remains as a part of tar. That is, it has a certain carbonization yield.

  Taking advantage of the above-mentioned characteristics of oxidized fibers and the characteristics of thermoplastic fibers, thermoplastic fibers can be effectively used as a binder between carbon fibers using the remaining amount of tar as a binder in an inert gas. Oxidized fibers and thermoplastic fibers It has been found that a spun yarn obtained by mixing and spinning under a predetermined condition is excellent in spinnability in the spinning process, excellent in fabric processability in the weaving process, and high in strength.

  Knowing that weaving, pressurizing heat treatment, and carbonization treatment of this oxidized fiber spun yarn yields a carbon fiber woven fabric with good shapeability and thinness with less surface fluff, and the present invention is completed. It was.

  Accordingly, an object of the present invention is to provide a thermoplastic fiber-mixed oxidized fiber spun yarn and a method for producing an oxidized fiber fabric and a carbon fiber fabric that solve the above problems.

  The present invention for achieving the above object is described below.

  [1] A spun yarn obtained by mixing and spinning oxidized fibers and thermoplastic fibers, wherein the carbonization yield of the thermoplastic fibers is 0.5 mass% or more, and the fineness of the thermoplastic fibers is 0.5 to 10. 0 dtex, oxide fiber fineness of 0.5 to 3.4 dtex, thermoplastic fiber mixing ratio of spun yarn of 7 to 45% by mass, spun yarn dry strength of 16 mN / dtex or more, spun yarn twist of several hundred to fifty Thermoplastic fiber mixed oxidized fiber spun yarn of 900 times / m.

[2] A fabric weight obtained by weaving the spun yarn according to [1] is subjected to pressure heat treatment at 100 to 350 ° C. and 0.5 to 100 MPa, and has a basis weight of 100 to 350 g / m ^2. A method for producing an oxidized fiber fabric having a bulk density of 0.40 to 0.95 g / cm ³ .

[3] The oxidized fiber woven fabric according to [2] is heat-treated in an inert gas at a temperature of 1000 to 2800 ° C., and has a basis weight of 60 to 210 g / m ² and a thickness of 0.14 to 0 A method for producing a carbon fiber fabric having a diameter of 0.6 mm and a bulk density of 0.25 to 0.55 g / cm ³ .

  The oxidized fiber spun yarn of the present invention is obtained by mixing and spinning oxidized fiber and thermoplastic fiber under predetermined conditions. Therefore, in the spinning process for obtaining it, the spun yarn is excellent in spinnability, and weaved it to give oxidized fiber fabric. In the weaving process to obtain a woven fabric, it is excellent in fabric processability and itself has high strength.

  The carbon fiber woven fabric of the present invention is a woven fabric having good shapeability, thinness and less surface fluff since the oxidized fiber spun yarn is woven, pressure heat treated, and carbonized.

  Hereinafter, the present invention will be described in detail.

  The thermoplastic fiber-mixed oxidized fiber spun yarn of the present invention is a spun yarn obtained by mixing and spinning thermoplastic fibers in an oxidized fiber, and has a dry strength of 16 mN / dtex or more. When the dry strength is less than 16 mN / dtex, yarn breakage is likely to occur during textile processing. The quality of the resulting fabric is reduced.

  The thermoplastic fiber-mixed oxidized fiber spun yarn of the present invention has a number of 150 to 900 times / m. If the number is less than 150 times / m, the spun yarn strength decreases, fabric processing is difficult, and fluff is likely to occur. If the number exceeds 900 times / m, the processability of the spun yarn is reduced, the single fiber is cut, and fluff is likely to occur.

  As for the thickness of the thermoplastic fiber mixed oxidized fiber spun yarn of this invention, 170-1000 dtex / book is preferable. When the thickness of the yarn is less than 170 dtex, the spun yarn strength decreases. Weaving becomes difficult. When the thickness of the yarn exceeds 1000 dtex / piece, a carbon fiber fabric having a desired thickness cannot be produced. Can not be thinned.

  Each material which comprises this thermoplastic fiber mixed oxidation fiber spun yarn is demonstrated with a manufacturing method.

[Thermoplastic fibers]
The mixing ratio of the thermoplastic fiber in the thermoplastic fiber-mixed oxidized fiber spun yarn of the present invention is 7 to 45% by mass. When the amount is less than 7% by mass, the effect of improving the spinning property is not recognized. No formability and strength improvement effect during carbonization treatment. When it exceeds 45 mass%, strength reduction and carbon fluff generation become remarkable during carbonization.

  The types of thermoplastic fibers are nylon fibers such as nylon 6 and nylon 66, polyethylene terephthalate (PET), polytrimethylene terephthalate, polybutylene terephthalate, polyarylate fiber, polyester fiber such as polylactic acid fiber, and polyacrylonitrile. Any conventionally known thermoplastic fibers such as acrylic fibers such as (PAN) and polyolefin fibers such as polypropylene (PP) and polyethylene can be used.

  The carbonization yield of the thermoplastic fiber is 0.5% by mass or more.

  The fineness of the thermoplastic fiber is 0.5 to 10 dtex, and preferably 1.0 to 5.0 dtex. If it is less than 0.5 dtex, the spreadability is poor, and homogeneous mixing with oxidized fibers is difficult. If it exceeds 10.0 dtex, a spun yarn with high strength cannot be obtained.

  The crimp rate of the thermoplastic fiber is preferably 8 to 20%. Outside this range, spinnability is low and yarn breakage often occurs. The spreadability is poor, and homogeneous mixing with oxidized fibers is difficult.

  The number of crimps of the thermoplastic fiber is preferably 3 to 7 / cm. If it is less than 3 pieces / cm, entanglement is difficult to occur and spun yarn processing is difficult. When it exceeds 7 pieces / cm, the single fiber strength is lowered, and fiber breakage tends to occur.

  The dry strength of the thermoplastic fiber is preferably 20 to 80 mN / dtex. The dry elongation of the thermoplastic fiber is preferably 25 to 50%. When the dry strength is less than 20 mN / dtex, or when the dry elongation is less than 25%, the contribution to improving the characteristics at the time of mixing with the oxidized fiber is lowered.

  The average cotton length of the thermoplastic fiber is preferably 35 to 100 mm. In the case of less than 35 mm, there is no entanglement, and the spun yarn strength decreases. When it exceeds 100 mm, it is difficult to spin as the uniform dispersibility of the fiber decreases.

[Oxidized fiber]
Any of the conventionally known fibers such as PAN-based, pitch-based, phenol-based, and rayon-based can be used as the precursor fiber used as the raw material for the oxidized fiber. In the spinning process, a PAN-based fiber having a relatively high strength and elongation is most preferable.

  For example, PAN-based oxidized fibers are obtained by a flameproofing treatment in which PAN-based fibers are treated in air at a high temperature to cause a cyclization reaction and increase the amount of oxygen bonds to make them infusible and flame-retardant.

  The fineness of the oxidized fiber is 0.5 to 3.5 dtex, and more preferably 1.0 to 3.2 dtex. If it is less than 0.5 dtex, the spreadability is poor, and homogeneous mixing with oxidized fibers is difficult. When it exceeds 3.5 dtex, a spun yarn with high strength cannot be obtained.

  The average cotton length of the oxidized fiber is preferably 35 to 150 mm. In the case of less than 35 mm, there is no entanglement, and the spun yarn strength decreases. If it exceeds 150 mm, spinning becomes difficult as the uniform dispersibility of the fibers decreases.

  The limiting oxygen index (LOI) of the oxidized fiber is preferably 30-60. If it is less than 30, strength deterioration and carbon fiber fine powder are likely to occur during carbonization. When it exceeds 60, the strength of the spun yarn at the time of spinning processing is lowered.

  The dry strength of the oxidized fiber is preferably 5 mN / dtex or more. The higher the dry strength, the better the spinnability. If it is less than 5 mN / dtex, fiber breakage occurs frequently and spinning is difficult.

  The dry elongation of the oxidized fiber is preferably 5 to 30%. The higher the dry elongation, the better the spinnability. If it is less than 5%, fiber breakage frequently occurs and spinning is difficult.

  The number of crimps of the oxidized fiber is preferably 2.4 to 5.0 / cm. If it is less than 2.4 pieces / cm, the spun yarn strength decreases during spinning. When it exceeds 5.0 pcs / cm, the crimp breakage frequently occurs during the crimping process.

  The crimp rate of the oxidized fiber is preferably 8 to 16%. If it is less than 8%, the spun yarn strength decreases during spinning. If it exceeds 16%, crimping frequently occurs during crimping.

[Weaving]
Next, the oxidized fiber spun yarn is woven to produce an oxidized fiber spun yarn fabric. The weaving form may be any of plain weave, twill weave, satin weave, cedar weave, etc., but plain weave is most preferable from the viewpoint of formability.

  The number of oxidized fiber spun yarns to be driven is not particularly limited, but is preferably 20 to 60 / 24.5 mm.

[Pressure heat treatment]
The oxidized fiber fabric of the present invention can be obtained by subjecting the spun yarn fabric to pressure heat treatment. The optimum conditions are somewhat different depending on the thermal characteristics of the thermoplastic fibers, but the following conditions are employed.

  The pressure heat treatment atmosphere is performed in an oxidizing atmosphere such as air.

  The temperature during the pressure heat treatment is preferably 100 to 350 ° C, more preferably 110 to 250 ° C. When the temperature is less than 100 ° C., effects such as improvement of formability to fabric, improvement of strength, and thinning cannot be obtained. When it exceeds 350 ° C., the fiber performance deteriorates. There is a risk of causing problems such as heat storage or ignition.

  The pressure during the pressure heat treatment is preferably 0.5 to 100 MPa, more preferably 2 to 50 MPa. In the case of less than 0.5 MPa, effects such as improvement of formability to fabric, improvement of strength, and thinning cannot be obtained. If it exceeds 100 MPa, the fiber performance deteriorates.

  The pressure heat treatment time is preferably maintained at the pressure heat treatment temperature for 0.1 seconds to 5 minutes.

The basis weight of the oxidized fiber fabric after the pressure heat treatment is preferably 100 to 350 g / m ² . If it is less than 100 g / m ² , the fabric strength is lowered. When it exceeds 350 g / m ² , it is difficult to produce a thin-layer woven fabric having a desired thickness. The basis weight can be adjusted by the thickness of the spun yarn and the number of driven yarns.

  The thickness of the oxidized fiber fabric after the pressure heat treatment is preferably 0.15 to 0.50 mm. In the case of less than 0.15 mm, the fabric strength decreases. When it exceeds 0.50 mm, it cannot be made to the thickness of the intended carbon fiber fabric.

[Carbonization treatment]
The carbon fiber fabric of the present invention can be obtained by carbonizing the oxidized fiber fabric. That is, the above-described oxidized fiber fabric is carbonized under the following carbonization conditions to produce a carbon fiber fabric having the following physical properties with less surface fluff.

  Carbonization is performed at 1000 to 2800 ° C. in an inert atmosphere such as nitrogen, helium, or argon. In addition, the temperature increase rate in the case of carbonization under temperature increase is preferably 200 ° C./min or less. When the temperature is lower than 1000 ° C., the inherent characteristics of the carbon fiber, that is, heat resistance, strength retention, electrical conductivity and the like are not exhibited. When the temperature exceeds 2800 ° C., a large amount of fine powder is generated as the fiber strength deteriorates. The residence time at the maximum temperature is preferably 0.5 to 20 minutes.

  At the time of carbonization, the oxidized fiber in the woven fabric remains in the form of fiber by 50 to 60% in terms of weight. On the other hand, the thermoplastic fiber melts and remains in an amount of 0.5 to 10% in terms of weight, and has an effect of binding carbon fibers (binder effect). By this effect, the shapeability and strength of the carbon fiber fabric can be improved, and a thin carbon fiber fabric with less surface fluff can be obtained.

  The thickness of the carbon fiber fabric is preferably 0.15 to 0.60 mm. In the case of less than 0.15 mm, the fabric strength decreases. When it exceeds 0.60 mm, the electrical conductivity in the thickness direction decreases and the surface fluff increases.

Basis weight of the carbon fiber woven fabric is preferably 60~210g / m ^2. When it is less than 60 g / m ² , the fabric strength is lowered. When it exceeds 210 g / m ² , it is difficult to produce a thin-layer woven fabric with a desired thickness, and the electrical resistance value increases.

The bulk density of the carbon fiber fabric is preferably 0.25 to 0.55 g / m ³ . If it is less than 0.25 g / m ³ , the strength of the fabric is lowered and the electrical conductivity is lowered. When it exceeds 0.55 g / m ³ , the fabric strength decreases and the surface fluff increases.

  The electric resistance value of the carbon fiber fabric is preferably 4.0 mΩ or less. If it exceeds 4 mΩ, the conductivity is low and application is difficult.

  The strength of the carbon fiber fabric is preferably 25 to 80 N / cm. When it is less than 25 N / cm, the handleability is lowered. If it exceeds 80 N / cm, it is difficult to produce.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. Each physical property was measured by the following method.

[LOI of oxidized fibers: limiting oxygen index]
The sample is placed in a mixed gas of oxygen and nitrogen, and the oxygen concentration (volume%) at which combustion and ignition start is LOI.

[Oxidized fiber mixing rate]
It is calculated from the input weight ratio in the mixing process of the blended cotton and the like during spinning.

[Fiber properties: fineness, dry strength, dry elongation, number of crimps, crimp rate, average fiber length]
Measured based on JIS L 1015.

[Thickness of spun yarn]
The spun yarn is 10 m in length, each of the five yarns is dried at 120 ° C. for 1 hour, and the calculated mass is calculated.

[Number of spun yarn]
Take out a length of 10 cm, measure the number using a magnifier with a magnification of 20 times, and convert it per m.

[Strong yarn strength]
The breaking strength when the spun yarn is held at a grip interval of 100 mm and pulled at a pulling speed of 30 mm / min is defined as spun yarn strength (N / piece).

[Weaving thickness]
The thickness when a 1.2 N load (61.9 kPa) is applied in the thickness direction with a circular pressure plate having a diameter of 5 mm is measured.

[Weaving basis weight]
It is calculated from the mass value after drying a 200 mm × 250 mm woven fabric at 120 ° C. for 1 hour.

[Textile strength]
This is a value obtained by converting the breaking strength when a sample having a width of 50 mm and a length of 120 mm or more is fixed to a jig having a distance between chucks of 100 mm and pulled at a speed of 30 mm / min to 10 mm.

[Electric resistance value]
Two 50mm square (thickness 10mm) gold-plated electrodes are sandwiched between carbon fiber spun yarn fabrics so that the electrodes are in full contact with each other, and the electric resistance value in the thickness direction when a load of 10kPa is applied in the thickness direction of the fabric. Measure.

[Surface fluff measurement method]
A carbon fiber fabric is cut into a width of 50 mm and a length of 200 mm. As shown in FIG. 1, the cut-out carbon fiber fabric 2 is wound around a metal pipe 4 having an outer diameter of 8 mm (curvature radius of 4 mm) half a turn. The end side 6 of the wound carbon fiber fabric is held down by a metal plate 8 having a mass of about 80 g (thickness 10 mm × width 30 mm × length 35 mm). The number of fluffs having a length of 0.5 mm or more is measured along the ridge line portion 10 at the top of the carbon fiber woven fabric half-wrapped.

  For the measurement, a photo is taken of the ridge portion using an optical microscope (50 times magnification). The number of fluffs is counted at five measurement points, and the average value is calculated.

[Examples 1 to 5]
Oxidized fibers and thermoplastic fibers were mixed and spun under the conditions shown in Table 1 to produce spun yarn (single yarn) having the physical properties shown in Table 1. Using this spun yarn, weaving was carried out under the conditions shown in Table 1 to produce a plain woven fabric. After pressurizing heat treatment under the conditions shown in Table 1, oxidized fiber woven fabrics having physical properties shown in Table 1 were obtained. This fabric is carbonized in an inert gas at the temperature ramp shown in Table 1, the maximum temperature reached after the temperature rise (shown as temperature in Table 1), and the residence time at the maximum temperature (shown as time in Table 1). Processed.

  As a result, as shown in Table 1, a carbon fiber woven fabric having good physical properties with a small amount of surface fluff was obtained in any of Examples 1 to 5.

[Comparative Examples 1-5]
Oxidized fiber and thermoplastic fiber were mixed and spun under the conditions shown in Table 2, but in Comparative Example 4, fiber cutting occurred during spinning, and a spun yarn could not be made. For Comparative Examples 1 to 3 and 5, spun yarn (single yarn) having the physical properties shown in Table 2 was obtained.

  Using this spun yarn, weaving was performed under the conditions shown in Table 2. However, in Comparative Examples 1 and 2, the spun yarn strength was low, so a woven fabric could not be made. For Comparative Examples 3 and 5, plain woven fabrics having the physical properties shown in Table 2 were obtained. After pressure heat treatment under the conditions shown in Table 2, oxidized fiber woven fabrics having physical properties shown in Table 2 were obtained. This fabric is carbonized in an inert gas with the temperature gradient shown in Table 2, the maximum temperature reached after temperature increase (indicated as temperature in Table 2), and the residence time at the maximum temperature (indicated as time in Table 2). Processed.

  As a result, as shown in Table 2, the amount of surface fluff was large in any of Comparative Examples 3 and 5, and a carbon fiber fabric with good physical properties could not be obtained.

  The part shown by x in Table 2 deviates from the configuration of the present invention.

[Comparative Examples 6 to 7 and Example 6]
Oxidized fibers and thermoplastic fibers were mixed and spun under the conditions shown in Table 3 to produce spun yarn (single yarn) having the physical properties shown in Table 3. Using this spun yarn, weaving was carried out under the conditions shown in Table 3 to prepare a plain woven fabric. After pressurizing heat treatment under the conditions shown in Table 3, an oxidized fiber woven fabric having physical properties shown in Table 3 was obtained. This fabric is carbonized in an inert gas at the temperature ramp shown in Table 3, the maximum temperature reached after temperature rise (shown as temperature in Table 3), and the residence time at the maximum temperature (shown as time in Table 3). Processed.

  As a result, as shown in Table 3, a carbon fiber woven fabric having good physical properties with a small amount of surface fluff was obtained in Example 6, whereas in Comparative Examples 6 to 7, carbon having a large amount of surface fluff and good physical properties was obtained. No fiber fabric was obtained.

  The part shown by x in Table 3 deviates from the configuration of the present invention.

It is explanatory drawing which shows the measuring method of the number of marks on the surface of a carbon fiber fabric.

Explanation of symbols

2 Carbon fiber fabric 4 Metal pipe 6 End side 8 Metal plate 10 Ridge part

Claims (3)

A spun yarn in which oxidized fiber and thermoplastic fiber are mixed and spun, and the carbonization yield of the thermoplastic fiber is 0.5 mass% or more, the fineness of the thermoplastic fiber is 0.5 to 10.0 dtex, oxidized The fineness of the fiber is 0.5 to 3.4 dtex, the mixing ratio of the thermoplastic fiber in the spun yarn is 7 to 45% by mass, the dry strength of the spun yarn is 16 mN / dtex or more, and the number of the spun yarn is several hundred to 900 times / m, a thermoplastic fiber-mixed oxidized fiber spun yarn. A spun yarn fabric obtained by weaving the spun yarn according to claim 1 is subjected to pressure heat treatment at 100 to 350 ° C. and 0.5 to 100 MPa, and has a basis weight of 100 to 350 g / m ² and a bulk density. Is a method for producing an oxidized fiber woven fabric of 0.40 to 0.95 g / cm ³ . The oxidized fiber fabric according to claim 2 is heat-treated in an inert gas at a temperature of 1000 to 2800 ° C, and has a basis weight of 60 to 210 g / m ² , a thickness of 0.14 to 0.6 mm, A method for producing a carbon fiber woven fabric having a bulk density of 0.25 to 0.55 g / cm ³ .

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