JP2022009524A - Weft for carbon fiber fabric and carbon fiber fabric using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a weft for carbon fiber fabric, which is adequate for unidirectional fabric whose flatness is not inhibited, and a carbon fiber fabric using the weft.

SOLUTION: A weft for a fabric using carbon fiber for warp is formed of a conjugate type thermal bonding fibers 14 obtained by compounding a low melting point thermoplastic polymer and a high melting point thermoplastic polymer having higher melting point than the low melting point thermoplastic polymer. The conjugate type thermal bonding fiber 14 is a core-sheath type thermal bonding fiber in which a high melting point polyester having melting point of 240°C or higher is used for a core portion 15 and a low melting point polyester having melting point of 110 to 200°C is used for a sheath portion 16. The weft is multifilament formed by binding a plurality of conjugate type thermal bonding fibers together.

SELECTED DRAWING: Figure 2

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to a warp and weft for a carbon fiber fabric and a carbon fiber fabric using the weft, and particularly for a carbon fiber fabric suitable for a unidirectional fabric in which the total fineness of the carbon fiber used for the warp is extremely larger than that of the weft. It relates to a warp and a carbon fiber woven fabric using this warp and weft.

Patent Document 1 describes a unidirectional woven fabric in which the total fineness of carbon fibers used for warp is extremely larger than that of warp and weft. Such a unidirectional woven fabric is suitably used as a carbon fiber material for a molded product using a carbon fiber reinforced resin.

In the unidirectional woven fabric described in Patent Document 1, warps having a large total fineness are composed of flat carbon fiber threads, and a large number of warps are arranged side by side, which is fine and has a low weave density. By weaving together with, a sheet-shaped woven fabric suitable for molding a fiber-reinforced molded product is obtained. As the weft, a yarn in which a heat-sealed fiber is attached to a glass fiber yarn is used (particularly, paragraph 0023 of Patent Document 1).

With such a configuration, the finished woven fabric has excellent flatness as compared with the case where the warp and weft made of carbon fiber having the same fineness are woven in a plain weave, and therefore a carbon fiber reinforced resin is used. It can have particularly preferable properties as a sheet-shaped carbon fiber material for a molded product.

In the unidirectional woven fabric of Patent Document 1, the glass fiber thread as a weft is adhered to the carbon fiber of the warp by the heat fusion action of the heat fusion fiber (particularly, paragraph 007 of Patent Document 1). ..

Japanese Unexamined Patent Publication No. 2013-129936

However, since the weft used in Patent Document 1 is composed of glass fibers, it is harder than the carbon fibers of the warp, and therefore, in the finished woven fabric, the glass fiber of the weft and the carbon fiber of the warp At the intersection with the glass fiber, the carbon fiber rises greatly upward in the intersection region where the glass fiber is located below, while in the intersection region where the glass fiber is located above, the carbon fiber sinks greatly downward and the entire sheet. The carbon fibers rise and fall up and down to generate waviness, and the waviness hinders the flatness of the sheet.

Therefore, the present invention solves such a problem and obtains a weft for carbon fiber woven fabric suitable for a unidirectional woven fabric whose flatness is not impaired and a carbon fiber woven fabric using this weft. The purpose.

In order to achieve this object, the warp and weft for carbon fiber woven fabric of the present invention is used.
Warp and weft for woven fabrics that use carbon fiber for the warp.
It is composed of a composite heat-sealing fiber in which a low melting point thermoplastic polymer and a high melting point thermoplastic polymer having a higher melting point than this low melting point thermoplastic polymer are composited.
The composite heat-fusing fiber has a core in the form of a filament in which a high melting point polyester having a melting point of 240 ° C. or higher is arranged in the core portion and a low melting point polyester having a melting point of 110 to 200 ° C. is arranged in the sheath portion. Sheath-type heat-sealing fiber,
The warp and weft is characterized by being a multifilament formed by converging a plurality of composite heat-sealing fibers.

In the carbon fiber woven fabric of the present invention, carbon fibers are arranged on the warp, the above-mentioned weft for carbon fiber woven fabric is arranged on the weft, and the high melting point heat as a fiber forming component is obtained by heat fusion of the low melting point thermoplastic polymer of the weft. It is characterized in that the plastic polymer is a woven fabric adhered to warp and weft.

According to the weft for carbon fiber woven fabric of the present invention, it is a composite type heat-sealing fiber in which a low melting point thermoplastic polymer and a high melting point thermoplastic polymer having a higher melting point than this low melting point thermoplastic polymer are composited. Since it is composed, it is possible to construct a weft with a high melting point thermoplastic polymer as a fiber forming component and a low melting point thermoplastic polymer as a heat bonding component, and therefore, compared with a weft made of a conventional glass fiber. Therefore, it is possible to satisfactorily prevent the occurrence of waviness in the finished woven fabric, and it is possible to obtain a carbon fiber woven fabric having excellent flatness. Further, the composite type heat-sealing fiber has a core-sheath type heat in which a high melting point polyester having a melting point of 240 ° C. or higher is arranged in the core portion and a low melting point polyester having a melting point of 110 to 200 ° C. is arranged in the sheath portion. Since it is a fused fiber, that is, since both the core portion and the sheath portion are made of a polyester-based polymer, it has the advantages of high versatility and excellent strength.

It is a figure which shows the carbon fiber woven fabric which used the weft for carbon fiber woven fabric of embodiment of this invention. It is a figure which shows the cross-sectional structure of the weft for the carbon fiber woven fabric. It is a figure which shows the adhesion state of the weft for carbon fiber woven fabric, and the warp and weft of carbon fiber. It is a figure which shows typically the vertical cross-sectional structure of a carbon fiber woven fabric.

The carbon fiber woven fabric 11 using the weft for carbon fiber woven fabric according to the embodiment of the present invention shown in FIG. 1 is woven using the warp 12 and the weft 13.

The warp 12 is composed of a multifilament in which a plurality of carbon fibers are aligned substantially in parallel and have no twist. For example, it is a multifilament composed of a plurality of carbon fibers, and is composed of a multifilament of about 800tex / 12000f to 3200tex / 48000f. Since the plurality of carbon fibers are aligned substantially in parallel, a flat multifilament structure having a width of 3.0 to 5.0 mm and a thickness of about 0.1 to 0.3 mm is formed. Thereby, it can be suitably used as a carbon fiber material for a molded product using the above-mentioned carbon fiber reinforced resin. The warps are preferably closely arranged without gaps, and the weaving density may be appropriately selected according to the width of the multifilament made of carbon fibers so as to be closely arranged. Among them, 3 pieces / 2.54 cm to 10 pieces / 2.54 cm are preferable.

The weft 13 is composed of a composite heat-sealing fiber in which a low melting point thermoplastic polymer and a high melting point thermoplastic polymer having a higher melting point than the low melting point thermoplastic polymer are composited. The form of the composite heat-fusing fiber is a filament which is a continuous fiber. The warp and weft 13 is composed of a multifilament in which a plurality of filaments are converged.

The multifilament is formed by focusing about 30 to 80 filaments (heat-fused fiber fibers) having a single fiber fineness of 3 to 8 decitex, and a total fineness of about 150 to 400 decitex is preferable.

By setting the fineness and weaving density of the warp and weft to the above ranges, as shown in FIG. 1, a plurality of strip-shaped warp 12s are arranged in the horizontal direction, and the warp threads 12 are extremely thin as compared with these warp threads 12. It is possible to obtain a carbon fiber woven fabric 11 in which the warp and weft 13 is arranged at a pitch considerably wider than the yarn diameter.

As described above, the carbon fiber woven fabric 11 can be suitably used as a sheet-shaped carbon fiber material for a molded product using a carbon fiber reinforced resin. In that case, the carbon fiber of the warp 12 constitutes the main component of the carbon fiber material. On the other hand, the warp and weft 13 made of the composite heat-sealing fiber does not lose its shape until the carbon fiber woven fabric 11 is incorporated into the resin for reinforcing the resin. It suffices to fulfill only the role of holding the warp threads 12 together. Therefore, it is sufficient to arrange the small diameter ones as described above with a wide pitch, that is, with a low weaving density.

FIG. 2 shows a configuration example of the weft 13 as a material constituting the woven fabric 11. In the weft 13 illustrated in FIG. 2, a plurality of core-sheath type heat-sealing fibers 14 are focused in the form of filaments as shown in the figure at the stage of the constituent material before forming the woven fabric 11. Each core-sheath type heat-sealing fiber 14 has a structure in which the above-mentioned high-low melting point thermoplastic polymer is arranged in the core portion 15 and the above-mentioned low-melting point thermoplastic polymer is arranged in the sheath portion 16. .. In the carbon fiber woven fabric 11 shown in FIG. 1, as shown in FIG. 3, the low melting point thermoplastic polymer in the sheath portion 16 of the core-sheath type heat-sealing fiber 14 of the weft 13 is softened or melted by heat, and at the same time, the carbon fiber woven fabric 11 is softened or melted by heat. The core portion 15 in a state in which the high melting point thermoplastic polymer of the core portion 15 maintains the fiber morphology without softening and melting, and the high melting point thermoplastic polymer in a state of maintaining the fiber morphology constitutes the sheath portion 16. The low melting point thermoplastic polymer 17 is used to bond the warp threads 12 made of multifilament carbon fibers.

The mass ratio of the low melting point thermoplastic polymer and the high melting point thermoplastic polymer in the composite heat-fusing fiber of the weft 13 is the required strength of the core portion 15 substantially constituting the weft 13 in the carbon fiber woven fabric 11 and the sheath. From the viewpoint of the adhesive strength of the low melting point thermoplastic polymer 17 constituting the portion 16, for example, the ratio of the high melting point thermoplastic polymer / the low melting point thermoplastic polymer is 2/8 to 8/2, particularly 3/1 to 5/5 is preferable.

The low melting point thermoplastic polymer and the high melting point thermoplastic polymer in the composite heat-fusing fiber of the weft 13 need to have the yarn-making property by melt spinning, and also have the necessary characteristics for forming the weft thread 13. It is necessary to have it, and it is necessary that the warp and weft 12 has good adhesion to carbon fibers. In consideration of these points, both polymers are polymers of the same type as each other, that is, polyester-based polymers. Since both polymers are polyester-based polymers, they have the advantages of high versatility and excellent strength.

The cross-sectional shape of the composite heat-sealing fiber constituting the weft 13 may be any of a round cross section, a modified cross section, a hollow cross section and the like as long as the desired performance is not impaired.

The low melting point thermoplastic polymer and the high melting point thermoplastic polymer in the composite heat-fusing fiber constituting the weft 13 are independently heat stabilizer, crystal nucleating agent, matting agent, pigment, light resistant agent, and weather resistant. Additives such as agents, lubricants, antioxidants, antibacterial agents, fragrances, plasticizers, dyes, surfactants, flame retardants, surface modifiers, various inorganics, organic electrolytes and the like may be contained.

The core-sheath type heat-sealing fiber 14 as a composite type heat-sealing fiber is available as a commercially available product. For example, as the multifilament composed of continuous fibers, "MELSET (registered trademark)" manufactured by Unitika Ltd. can be used.

As the composite heat-fusing fiber constituting the weft 13, two or more types of composites having different physical properties such as melting point of low melting point thermoplastic polymer and high melting point thermoplastic polymer, mass ratio, fineness, strength and elongation of both. Molded thermoplastic fibers may be used.

The melting point of the low melting point thermoplastic polymer as a thermal adhesion component is preferably 20 ° C. or higher lower than the melting point of the high melting point thermoplastic polymer as a fiber forming component. With such temperature characteristics, there is an advantage that the physical properties of the refractory thermoplastic polymer are not affected even if it is subjected to the heat treatment described later, and the fiber morphology can be well maintained. The melting point of the low melting point thermoplastic polymer is preferably in the range of 80 to 200 ° C. in consideration of processability, various physical properties and the like. When the low melting point thermoplastic polymer does not have a definite melting point, the softening point of the low melting point thermoplastic polymer can be regarded as the melting point.

Specific preferred combinations of the low melting point thermoplastic polymer and the high melting point thermoplastic polymer include low melting point polyester and high melting point polyester in consideration of compatibility and thermal adhesion between the two.

As the core-sheath type composite heat-sealing fiber 1, specifically, a high melting point polyester having a melting point of 240 ° C. or higher is arranged in the core portion, and a low melting point copolymerized polyester having a melting point of 110 to 200 ° C. is used. A core-sheath type polyester fiber arranged in a sheath is used.

As a method for melting the low melting point thermoplastic polymer which is a heat fusion component, heat treatment can be mentioned. The heat treatment is a process of maintaining an atmospheric temperature higher than the melting point of the low melting point thermoplastic polymer. As a result, the warp and weft 13 can be adhered to each other as shown in FIG. 3 by melting and solidifying the low melting point thermoplastic polymer which is a heat fusion component.

When two or more types of composite threads containing different types of low melting point thermoplastic polymers are used as the weft 13, the melting point of the low melting point thermoplastic polymer having the highest melting point is used as a reference, and the melting point is the highest. Melting point The heat treatment may be performed at an atmospheric temperature higher than the melting point of the thermoplastic polymer. The ambient temperature during the heat treatment is preferably higher than the melting point of the low melting point thermoplastic polymer and lower than the melting point of the high melting point thermoplastic polymer. If the atmospheric temperature is too high, not only is it disadvantageous in terms of cost, but also the refractory thermoplastic polymer is damaged by heat, resulting in a decrease in the strength of the weft 13. The atmospheric temperature is preferably Mp _L + 5 ° C. or higher and Mp _L + 20 ° C. or lower, when the melting point of the low melting point thermoplastic polymer is expressed as Mp _L.

The time for applying the heat treatment may be any time as long as the low melting point thermoplastic polymer is sufficiently melted. However, if the heat treatment time is too long, not only is it disadvantageous in terms of cost, but also the refractory thermoplastic polymer is damaged by heat, and the strength of the weft 13 as a whole is lowered. Therefore, the heat treatment time is preferably 30 seconds to 5 minutes, more preferably 1 minute to 3 minutes. The heating method for applying the heat treatment is not particularly limited, but a well-known means such as an iron, a hot air welder, a hot air dryer, a tenter machine, a hot roller, and a hot press can be used.

According to the carbon fiber woven fabric 11 using the above-mentioned weft 13, the weft 13 is more flexible than the weft made of conventional glass fibers, and therefore the occurrence of waviness in the finished woven fabric 11 is satisfactorily prevented. It is possible to obtain a carbon fiber woven fabric 11 having excellent flatness.

FIG. 4 is a schematic comparison of the flatness of a carbon fiber woven fabric when a conventional weft made of glass fiber is used and when a weft based on the present invention is used. FIG. 2A shows a conventional configuration, in which 12 is a warp and 13 is a weft. The weft 13 was composed of a glass fiber yarn containing a plurality of glass fibers and a binder yarn containing a plurality of binder fibers. However, the binder fibers are softened and melted by the heat treatment, and the binder does not retain its fiber morphology. 21 is obtained, and the glass fiber 22 is adhered to the warp thread 12 composed of carbon fibers. However, the glass fiber 22 of the weft 13 is harder than the carbon fiber of the warp thread 12. Therefore, in the finished woven fabric, as shown in the figure, at the intersection of the glass fiber 22 of the weft 13 and the carbon fiber of the warp 12, the carbon fiber of the warp 12 moves upward in the intersection region where the glass fiber 22 is located below. On the other hand, in the crossing region where the glass fiber 22 is located above, the carbon fiber of the warp 12 sinks greatly downward. As a result, as shown in the figure, the carbon fibers of the warp 12 rise and fall up and down in the entire sheet to generate waviness, and the waviness hinders the flatness of the sheet, that is, the woven fabric.

On the other hand, FIG. 4B shows a configuration when the weft 13 of the present invention is used. As described above, since the warp and weft 13 is more flexible than the conventional warp and weft made of glass fiber, as shown in the figure, it is possible to satisfactorily prevent the occurrence of waviness in the finished woven fabric 11 and to have flatness. It is possible to obtain an excellent carbon fiber woven fabric 11.

In order to make the weft 13 flexible, in addition to the present invention, the weft 13 is made of synthetic resin fiber instead of the conventional glass fiber, and the yarn made of this synthetic resin fiber and the binder having a low melting point are used. It is also possible to consider a configuration in which a yarn made of fibers is used in combination to heat-adhere to the warp and weft. However, in that case, a plurality of types of fibers, that is, a yarn made of synthetic resin fibers and a yarn made of binder fibers, must be used as the weft. On the other hand, the weft 13 of the present invention is a composite heat-fused fiber in which a low melting point thermoplastic polymer and a high melting point thermoplastic polymer having a higher melting point than the low melting point thermoplastic polymer are composited. , It is enough to use only one kind of composite fiber. Furthermore, since it is composed of only composite heat-sealing fibers, it also has an effect of excellent adhesion of warp threads to carbon fibers. In addition, since only the refractory thermoplastic polymer that constitutes a part of this one type of fiber functions as a fiber component, it is about the same as a general synthetic resin fiber that is bonded with a binder from the viewpoint of handleability and the like. Even when the fiber having the fineness of the above is used, the fineness of the weft in the finished woven fabric can be lowered as compared with the case where the general synthetic resin fiber is used. That is, the weft can be made thinner, and from that point as well, the occurrence of waviness in the woven fabric 11 can be effectively prevented, and the smoothness of the woven fabric can be improved.

(Example 1)
A 2310tex carbon fiber roving yarn in which a plurality of carbon fibers are aligned is arranged in the warp and weft, and a multifilament (280dtex / 48f, polyethylene terephthalate in the core and melting point in the sheath) made of polyester core-sheath type continuous fiber is arranged in the weft. A woven fabric having a warp and weft density of 6.8 / 2.54 cm and a warp and weft density of 3.7 / 2.54 cm was produced using a copolymerized polyester at 160 ° C. and a trade name “MELSET” manufactured by Unitica. The produced woven fabric was heat-treated at 180 ° C. with a hot roll press to obtain a sheet having a thickness of 0.2 mm.

(Comparative Example 1)
Compared to Example 1, a multifilament yarn (Unitika Trading) consisting of 68tex glass fiber (Unitika "G150S / 1 / 0-1Z") and polyamide-based fully fused type heat-fused fiber with a total fineness of 330 dex. The difference from the company's product name "Flor M") was that a synthetic twisted yarn that was S-twisted at 50 T / m was used as the weft. Then, a sheet was obtained in the same manner as in Example 1 except for the above.

When the appearance of the sheets of Example 1 and Comparative Example 1, that is, the carbon fiber woven fabric was visually confirmed, the sheet of Example 1 had little waviness and was excellent in flatness. On the other hand, since the sheet of Comparative Example 1 used glass fiber for the weft, remarkable waviness occurred, and the sheet was inferior in flatness to the sheets of Examples 1 and 2.

Claims (2)

Warp and weft for woven fabrics that use carbon fiber for the warp.
It is composed of a composite heat-sealing fiber in which a low melting point thermoplastic polymer and a high melting point thermoplastic polymer having a higher melting point than this low melting point thermoplastic polymer are composited.
The composite heat-fusing fiber has a core in the form of a filament in which a high melting point polyester having a melting point of 240 ° C. or higher is arranged in the core portion and a low melting point polyester having a melting point of 110 to 200 ° C. is arranged in the sheath portion. Sheath-type heat-sealing fiber,
The warp and weft is a weft for carbon fiber woven fabric, which is a multifilament formed by converging a plurality of composite heat-sealing fibers. Carbon fibers are arranged in the warp, the weft for carbon fiber fabric according to claim 1 is arranged in the weft, and the high melting point thermoplastic polymer as a fiber forming component becomes the warp by heat fusion of the low melting point thermoplastic polymer of the weft. A carbon fiber woven fabric characterized by being a bonded woven fabric.

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