TWI828774B - Carbon fiber sheet material, prepreg, molded body, method of producing carbon fiber sheet material, method of producing prepreg and method of producing molded body - Google Patents

Abstract

A carbon fiber sheet material of the present invention includes a plurality of carbon fibers and a binder that binds the carbon fibers, wherein the carbon fibers includes first carbon fibers that are virgin carbon fibers and second carbon fibers that are recycled carbon fibers. When an average length of the first carbon fibers is L_VCF [mm] and an average length of the second carbon fibers is L_RCF [mm], it is preferred that a relationship of 1.1

L_VCF/L_RCF

Description

Carbon fiber sheet, prepreg material, molded body, manufacturing method of carbon fiber sheet, manufacturing method of prepreg material Methods and methods for manufacturing shaped bodies

The present invention relates to a carbon fiber sheet, a prepreg, a formed body, a method for manufacturing a carbon fiber sheet, a method for manufacturing a prepreg, and a method for manufacturing a shaped body.

Fiber-reinforced sheets or fiber-reinforced resin molding systems using them are used in various fields such as vehicles and aircraft. In particular, Fiber Reinforced Plastic (FRP) uses embedded reinforcing fibers to reinforce the plastic, thereby achieving excellent strength that is absolutely impossible to achieve in plastic alone.

Among them, carbon fiber reinforced plastics (CFRP) using carbon fibers with excellent physical properties have attracted much attention (see Patent Document 1).

In conventional CFRP, in order to take advantage of the excellent physical properties of carbon fibers, long carbon fibers are often used. dimension, and use carbon fibers as fabrics.

However, such CFRP has a problem in that its formability is poor when producing a molded body having a predetermined three-dimensional structure from a sheet material such as a prepreg material. Furthermore, in the manufactured molded article, unexpected unevenness may easily occur in the distribution of fibers and resin materials. For example, near the surface of the molded article, there is a region where more carbon fibers are exposed and the amount of carbon fibers exposed is smaller. There are problems such as a reduction in local strength due to the coexistence of areas with less resin material and more exposed resin material.

From the viewpoint of effective utilization of resources, there is also a demand for carbon fiber recycling.

However, a problem with the conventional technology is that satisfactory strength or reliability cannot be obtained when recycled carbon fibers are used.

[Prior technical literature] [Invention patent documents]

[Invention Patent Document 1] Japanese Patent Application Publication No. 2014-077209.

An object of the present invention is to provide a molded article excellent in strength and reliability and to provide a prepreg that can be used to produce a molded article excellent in strength and reliability with excellent formability. material; provide a carbon fiber sheet that is excellent in its own strength and reliability and can be used to produce molded bodies excellent in strength and reliability with excellent formability; and provide a carbon fiber sheet that can stably produce such shapes. Methods for manufacturing body, prepreg material and carbon fiber sheet.

The above objects can be achieved by the present invention described in the following (1) to (27).

(1) A carbon fiber sheet, which includes a plurality of carbon fibers and a binder used to connect the carbon fibers, wherein the carbon fibers include a first carbon fiber of original carbon fiber and a second carbon fiber of recycled carbon fiber. Carbon fiber.

(2) The carbon fiber sheet according to the above (1), wherein the average length of the second carbon fibers is shorter than the average length of the first carbon fibers.

(3) The carbon fiber sheet according to the above (2), wherein the average length of the first carbon fiber is L _VCF [mm] and the average length of the second carbon fiber is L _RCF [mm]. , which satisfies the relational expression of 1.1≦L _VCF /L _RCF ≦30.

(4) The carbon fiber sheet according to any one of (1) to (3) above, wherein the average length of the second carbon fibers is 1.0 mm or more and 10 mm or less.

(5) The carbon fiber sheet according to any one of the above (1) to (4), wherein the first carbon fiber content is X _VCF [mass %] and the second carbon fiber content is When the content rate is X _RCF [mass %], it satisfies _the relational expression 0.006≦X _VCF /

(6) The carbon fiber sheet according to any one of the above (1) to (5), wherein the second carbon fiber is derived from a recycled raw material having the second carbon fiber as an attachment on its surface. organic components and/or carbonized products of the organic components.

(7) The carbon fiber sheet according to the above (6), wherein the coverage rate of the attachments on the surface of the second carbon fiber is 2% or more and 40% or less.

(8) The carbon fiber sheet according to the above (6) or (7), which includes a bundle in which a plurality of the second carbon fibers are connected into a bundle through the attachment.

(9) The carbon fiber sheet according to the above (8), wherein the aspect ratio relative to the length of the width of the bundled body is 2 to 500.

(10) A prepreg material obtained by impregnating the carbon fiber sheet according to any one of the above (1) to (9) with a resin material.

(11) A prepreg material including a plurality of carbon fibers, a plurality of resin fibers, and a binder for connecting the carbon fibers and the resin fibers, wherein the carbon fibers include first carbon fibers of original carbon fibers. and the second carbon fiber of recycled carbon fiber.

(12) The prepreg material according to the above (11), wherein the average length of the resin fibers is 2.0 mm or more and 20 mm or less.

(13) The prepreg material according to the above (11) or (12), wherein the carbon fiber content ratio is X _CF [mass %] and the resin fiber content ratio is X _RF [mass %] When , the system satisfies the relational expression of 0.30≦X _CF /X _RF ≦28.

(14) The prepreg material according to any one of the above (11) to (13), wherein the average length of the carbon fiber is L _CF [mm] and the average length of the resin fiber is L _RF [ mm], it satisfies the relational expression of 0.10≦L _RF /L _CF ≦18.

(15) The prepreg material according to any one of (11) to (14) above, wherein the average length of the second carbon fibers is shorter than the average length of the first carbon fibers.

(16) The prepreg material according to the above (15), wherein the average length of the first carbon fiber is L _VCF [mm] and the average length of the second carbon fiber is L _RCF [mm], It satisfies the relational expression of 1.1≦L _VCF /L _RCF ≦30.

(17) The prepreg material according to any one of the above (11) to (16), wherein the average length of the second carbon fibers is 1.0 mm or more and 10 mm or less.

(18) The prepreg material according to any one of the above (11) to (17), wherein the first carbon fiber content is X _VCF [mass %], and the second carbon fiber content is When the ratio is X _RCF [mass %], it satisfies the relationship _of 0.006≦X _VCF /

(19) The prepreg material according to any one of the above (11) to (18), wherein the second carbon fiber is derived from a recycled raw material having the second carbon fiber attached as an attachment on its surface. Organic components and/or carbonized products of the organic components.

(20) The prepreg material according to the above (19), wherein the coverage rate of the attachments on the surface of the second carbon fiber is 2% or more and 40% or less.

(21) The prepreg material according to the above (19) or (20), which includes a bundle in which a plurality of the second carbon fibers are connected into a bundle through the attachment.

(22) The prepreg material according to the above (21), wherein the aspect ratio relative to the length of the width of the bundled body is 2 to 500.

(23) A molded article formed by heating and pressing the prepreg material according to any one of the above (10) to (22).

(24) A method for manufacturing a carbon fiber sheet, which includes: first carbon fiber of original carbon fiber, second carbon fiber of recycled carbon fiber, and a second carbon fiber for connecting the first carbon fiber and the second carbon fiber. The step of mixing the adhesive.

(25) A method of manufacturing a prepreg, which includes the step of impregnating a carbon fiber sheet produced by the method described in (24) above with a resin material.

(26) A method for manufacturing a prepreg material, which includes combining first carbon fibers of original carbon fibers, second carbon fibers of recycled carbon fibers, resin fibers, and connecting the first carbon fibers and the second carbon fibers. The carbon fiber and the binder of the aforementioned resin fiber are mixed and copied.

(27) A method of manufacturing a molded article, which includes the step of heating and press-molding a prepreg produced using the method described in (25) or (26) above.

According to the present invention, it is possible to provide a molded body that is excellent in strength and reliability; to provide a prepreg material that can be used to produce a molded body that is excellent in strength and reliability with excellent formability; and to provide a molded body that has its own strength. and carbon fiber sheets that are excellent in reliability and can be used to produce molded bodies that are excellent in strength and reliability with excellent formability; and provide a method that can stably produce such molded bodies, prepregs and carbon fiber sheets The method of manufacturing the material.

1, 11, 12: Carbon fiber

2: Attachments

10: fascicle

20: Adhesive

30: Resin material (impregnated with resin)

40:Resin fiber

100: Carbon fiber sheet

200: Prepreg material

Figure 1 is a schematic top view showing a preferred embodiment of the carbon fiber sheet of the present invention.

Figure 2 is a schematic longitudinal cross-sectional view showing a preferred embodiment of the carbon fiber sheet of the present invention.

FIG. 3 is a schematic top view showing Embodiment 1 of the prepreg material of the present invention.

FIG. 4 is a schematic top view showing Embodiment 2 of the prepreg material of the present invention.

The following is a detailed description of the preferred embodiments of the present invention.

In the following description, the same names and symbols refer to the same or homogeneous members, and detailed descriptions are appropriately omitted. In this specification, "sheet" refers not only to a single sheet, but also to a laminate, a mat, or a block in which the single sheets are laminated into a plurality of layers. mean.

[Carbon fiber sheet]

First, the carbon fiber sheet of the present invention will be described.

Figure 1 is a schematic top view showing a preferred embodiment of the carbon fiber sheet of the present invention, and Figure 2 is a schematic longitudinal cross-sectional view showing a preferred embodiment of the carbon fiber sheet of the present invention. In addition, in FIG. 2 , illustration of the attachment 2 and the adhesive 20 is omitted.

The carbon fiber sheet 100 includes a plurality of carbon fibers 1 and an adhesive 20 used to connect the carbon fibers 1 . Next, the carbon fibers 1 include first carbon fibers 11 of original carbon fibers and second carbon fibers 12 of recovered carbon fibers.

With such a structure, the carbon fiber sheet 100 excellent in strength and reliability can be provided. Such a carbon fiber sheet 100 can be appropriately used to produce a sheet with excellent formability, strength and reliability. Excellent molded body.

Further detailed description is provided below. That is, by including the first carbon fibers 11 that are less prone to quality deterioration and have higher quality original carbon fibers, the strength and reliability of the entire carbon fiber sheet 100 can be improved, and the use of carbon fibers can be improved. The strength of the molded body produced from the fiber sheet 100 also becomes excellent. Furthermore, generally speaking, recycled carbon fibers have excellent affinity with resin materials such as binders, which can improve the processability and formability of carbon fiber sheets compared to the case of using virgin carbon fibers. It is excellent and can appropriately prevent the occurrence of defects in molded objects produced using carbon fiber sheets, and can make the reliability of the molded object excellent. Furthermore, since molding defects are less likely to occur, it is particularly suitable for the production of molded articles having a fine structure or molded articles having small parts with a radius of curvature. Generally speaking, the fractured portions of the recycled carbon fibers formed during recycling are likely to become rough, which can easily lead to entanglement and hooking of the fibers, and can also easily become excellent with resin materials such as the adhesive 20. of adhesion. Furthermore, the recovered carbon fiber can be stably and stably controlled by appropriately controlling the amount of attachment (coverage rate) of the attachment 2 described below, the constituent materials, and the formation of bundles 10 of a predetermined shape according to the recovery conditions. The quality of the carbon fiber sheet 100, the molded body, etc. can be easily improved.

In addition, since excellent formability is obtained during the production of the molded article, the production conditions (for example, temperature, pressure, etc.) of the molded article can be relaxed. This makes it possible to use an object with a simple structure as a manufacturing device, or to suppress the load on the manufacturing device to extend the life of the manufacturing device. Furthermore, it is also advantageous from the viewpoint of suppressing the production cost of the molded body.

In addition, since excellent formability can be maintained even if the content rate of carbon fiber is increased, the content rate of the resin material can be reduced, so that the excellent properties of carbon fiber (such as strength and thermal conductivity) can be more effectively exhibited in the molded article. properties, conductivity, etc.).

In addition, by using the recycled second carbon fiber 12, it is also preferable from the viewpoints of saving resources and reducing environmental load.

On the other hand, if the above-mentioned conditions are not satisfied, the above-mentioned excellent effects cannot be obtained.

For example, when only virgin carbon fibers are used as carbon fibers without using recycled carbon fibers, it is difficult to achieve extremely excellent adhesion between the carbon fibers and resin materials such as binders, and it is difficult to make carbon fiber sheets. The formability of the material or the prepreg produced using the carbon fiber sheet, or the reliability of the carbon fiber sheet or the molded article produced using the carbon fiber sheet, have become very excellent.

In addition, when only recycled carbon fibers are used as carbon fibers without using original carbon fibers, it is difficult to increase the strength of carbon fiber sheets or molded articles produced using the carbon fiber sheets. Excellent.

(1st carbon fiber)

As mentioned above, the carbon fiber sheet 100 includes original carbon fibers (first carbon fibers 11) as the carbon fibers 1.

By including the first carbon fiber 11 which is a higher quality original carbon fiber that is less prone to quality deterioration, the overall strength and reliability of the carbon fiber sheet 100 can be improved, and the carbon fiber sheet can be used. The strength of the molded body produced by 100 also becomes excellent.

Furthermore, by including the second carbon fiber 12 (recycled carbon fiber) which will be described in detail later and including the first carbon fiber 11 (original carbon fiber), for example, compared with the case where no virgin carbon fiber is used, it is possible to The ratio of the bundled body in which a plurality of carbon fibers are connected to form a bundle and the carbon fibers that are not bundled, or the distribution of the carbon fiber lengths is appropriately adjusted. As a result, the properties of the carbon fiber sheet 100 or the molded article can be appropriately controlled.

The average length of the first carbon fiber 11 (the same is true for the average length of the first carbon fiber 11 included in the prepreg 200 and the molded body described later) is preferably 1.5 mm or more and 30 mm or less, and more preferably 2.0 mm. mm and above and below 20mm, and preferably above 4.0mm and below 16mm.

Thereby, the strength of the carbon fiber sheet 100, the molded body, etc. can be made more excellent, and at the same time, defects that may occur during molding can be more effectively prevented, and the reliability of the carbon fiber sheet 100, the molded body, etc. can be improved. Become better.

In addition, in the present invention, for example, 100 fibers can be randomly extracted from the fibers included in the randomly selected field of view of microscope observation, and the average of the lengths can be used as the average length of the fibers. In addition, when one field of view does not contain 100 fibers, a total of 100 fibers can be randomly extracted from multiple different fields of view, and the average of the lengths is used as the average. length.

The average width of the first carbon fiber 11 (the same is true for the average width of the first carbon fiber 11 included in the prepreg 200 and the molded body described later) is preferably 1.0 μm or more and 20 μm or less, and more preferably 2.0 μm or more. μm or more and 18 μm or less, and more preferably 3.0 μm or more and 15 μm or less.

Thereby, the strength of the carbon fiber sheet 100, the molded body, etc. can be made very excellent, and the processability and formability of the carbon fiber sheet 100 etc. can become especially excellent. Furthermore, it is possible to more effectively prevent unexpected unevenness on the surface of the carbon fiber sheet 100 or the molded body.

In addition, in this specification, for example, 100 fibers included in the randomly selected field of view of microscope observation can be randomly extracted, and the average value of the widths can be used as the average width of the fibers. In addition, when one field of view does not contain 100 fibers, a total of 100 fibers can be randomly extracted from multiple different fields of view, and the average of the widths is used as the average width.

The content rate of the first carbon fiber 11 in the carbon fiber sheet 100 is preferably from 0.5% by mass to 40% by mass, more preferably from 1.0% by mass to 30% by mass, and even more preferably from 1.0% to 30% by mass. It is 1.5 mass % or more and 20 mass % or less.

By satisfying such conditions, the effect (synergetic effect) produced by the coexistence of the first carbon fiber 11 and the second carbon fiber 12 is more significantly exerted.

In addition, a plurality of types of carbon fibers produced under different conditions may also be used as the first carbon fibers 11 .

(2nd carbon fiber)

As mentioned above, the carbon fiber sheet 100 includes the recycled carbon fibers (second carbon fibers 12 ) as the carbon fibers 1 .

Although the average length of the second carbon fibers 12 is not particularly limited, it is preferably shorter than the average length of the first carbon fibers 11 .

Thereby, the formability of the carbon fiber sheet 100, prepreg, etc. can be further improved. It can also more effectively prevent undesirable conditions that occur during molding (such as local strength reduction, poor appearance, etc. caused by unexpected uneven distribution of fibers and resin materials). Furthermore, since molding defects are less likely to occur, it is particularly suitable for the production of molded articles having a fine structure or molded articles having a small portion with a radius of curvature.

When the average length of the first carbon fiber 11 is L _VCF [mm] and the average length of the second carbon fiber 12 is L _RCF [mm], the relationship of 1.1≦L _VCF /L _RCF ≦30 is preferably satisfied. The formula is preferably a relational expression satisfying 1.3≦L _VCF /L _RCF ≦12, and still more preferably a relational expression satisfying 1.8≦L _VCF /L _RCF ≦7.0.

In this way, the above-mentioned effects can be more effectively exerted, and the strength of the carbon fiber sheet 100 or the formed body can be made more excellent.

Although the average length of the second carbon fiber 12 is not particularly limited (the average length of the second carbon fiber 12 included in the prepreg 200 and the molded body to be described later is the same), it is preferably 1.0 mm or more and 10 mm. Below, it is more preferably not less than 1.5mm and not more than 9.0mm, and still more preferably not less than 2.0mm and not more than 8.0mm.

In this way, the above-mentioned effects can be more effectively exerted, and the strength of the carbon fiber sheet 100 or the formed body can be made more excellent. Furthermore, internal stress is less likely to accumulate even when exposed to heat, so dimensional accuracy can be improved and unexpected deformation during use of the molded body is less likely to occur.

The average width of the second carbon fiber 12 (the same applies to the average width of the second carbon fiber 12 included in the prepreg 200 and the molded body described later) is preferably 1.0 μm or more and 20 μm or less, more preferably 2.0 μm. More than 18 μm and less, more preferably, not less than 3.0 μm and not more than 15 μm.

Thereby, the strength of the carbon fiber sheet 100, the molded body, etc. can be made very excellent, and the processability and formability of the carbon fiber sheet 100 etc. can become especially excellent. Furthermore, it is possible to more effectively prevent unexpected unevenness on the surface of the carbon fiber sheet 100 or the molded body.

Although the second carbon fiber 12 only needs to be recycled, it is made from carbon fiber reinforced plastic (Carbon fiber reinforced plastic). Fiber Reinforced Plastics; CFRP) is preferred.

CFRP generally uses high-quality carbon fibers, and by using the second carbon fibers 12 recovered from CFRP, the quality of the carbon fiber sheet 100, molded products, etc. can be improved. Furthermore, by using CFRP as a recycled raw material, it is possible to more appropriately control the formation of the bundle 10 described later, the composition of the deposit 2 , or the adjustment of the deposit amount.

The second carbon fiber 12 can be recovered by any method. For example, it can be obtained by appropriately heat-treating crushed or pulverized recycled raw materials.

Although the heat treatment conditions for the recovered raw materials are not particularly limited, for example, by performing the first heat treatment (heat treatment mainly for the purpose of thermal decomposition of the resin material) at a temperature of 300°C or more and 400°C or less in an air atmosphere, and The second carbon fiber 12 satisfying the above conditions can be appropriately obtained by performing the second heat treatment (heat treatment mainly for the purpose of removing carbonized residues) at a temperature of 400°C to 600°C in an air atmosphere.

In addition, a plurality of types of carbon fibers recovered under different conditions can also be used as the second carbon fibers 12 .

In this embodiment, the second carbon fiber 12 has an organic component derived from the recycled raw material (for example, CFRP, etc.) of the second carbon fiber 12 as attachment 2 and/or a carbonized product of the organic component adhered to its surface. .

Such attachment 2 has excellent adhesion to the carbon fiber compared with attachments that are generally attached to the original carbon fiber as a post-treatment. In addition, the attachment 2 has excellent affinity with the adhesive 20 or the resin material (impregnated resin) 30 or the like. This is beneficial to further improving the strength and reliability of the carbon fiber sheet 100, the formed body, and the like. Furthermore, by adhering the attachment 2 to the surface of the second carbon fiber 12, the bundled body 10 described below can be formed more appropriately, and the strength and stability of the bundled body 10 can be further improved.

Examples of the organic component system include sizing agent, matrix resin, and the like.

Although the coverage rate of the attachment 2 on the surface of the second carbon fiber 12 is not particularly limited (the same applies to the coverage rate of the attachment 2 on the surface of the second carbon fiber 12 contained in the prepreg 200 and the molded article described later), but Preferably, the ratio is between 2% and below 40%, more preferably between 4% and below 30%, and still more preferably between 6% and below.

In this way, the strength and reliability of the carbon fiber sheet 100 or the formed body can be further improved.

In this embodiment, the bundled body 10 includes a plurality of second carbon fibers 12 connected in a bundled shape.

In this way, the strength and reliability of the carbon fiber sheet 100 or the formed body can be further improved.

In particular, this embodiment includes a bundle 10 in which a plurality of second carbon fibers 12 are connected into a bundle through the attachment 2 .

In this way, the strength and stability of the bundled body 10 itself can be improved, and the strength and reliability of the carbon fiber sheet 100 or the formed body can be further improved.

The aspect ratio (L/W) relative to the ratio (L/W) of the length L of the width W of the bundled body 10 (the same applies to the bundled body 10 included in the prepreg 200 and the molded body to be described later) is preferably It should be above 2 and below 500, preferably above 10 and below 450, and still more preferably above 20 and below 400.

By satisfying such conditions, the formability (processability such as bending) of the molded object during manufacturing can be improved, and the strength and reliability of the carbon fiber sheet 100 or the molded object can be further improved.

In addition, when the carbon fiber sheet 100 (the same applies to the prepreg 200 and the molded body described later) includes a plurality of bundles 10, the average of the aspect ratios of the plurality of bundles 10 satisfies The conditions as mentioned above are preferred.

In addition, the average value of the aspect ratio can be, for example, randomly selecting 100 bundles 10 included in the field of view of a randomly selected microscope observation, and using the values of the obtained aspect ratios. The average is taken as the average of the aspect ratios. In addition, when one field of view does not contain 100 fascicles, a total of 100 fascicles 10 can be randomly selected from a plurality of different fields of view and collected. Use the average of these aspect ratios.

Furthermore, in the structure of the drawings, in the carbon fiber sheet 100 (the same applies to the prepreg 200 and the molded body described later), in addition to the second carbon fibers 12 constituting the bundled body 10, the carbon fiber sheet 100 also includes the second carbon fibers 12 that are not bundled. The second carbon fiber 12 of the body 10.

This achieves a higher level of both excellent strength and ease of handling (including formability).

When the content rate of the first carbon fiber 11 in the carbon fiber sheet 100 is X _VCF [mass %] and the content rate of the second carbon fiber 12 is X _RCF [mass %], it is preferable to satisfy 0.006≦ X _VCF /X _{RCF ≦ 1.0} , more preferably a relation satisfying 0.015 ≦ X _{VCF /}

By satisfying such conditions, the effect (synergistic effect) produced by the coexistence of the first carbon fiber 11 and the second carbon fiber 12 is more significantly exerted.

The content rate of the second carbon fiber 12 in the carbon fiber sheet 100 is preferably 40 mass% or more and 99 mass% or less, more preferably 50 mass% or more and 98 mass% or less, and still more preferably More than 60% by mass and less than 97% by mass.

By satisfying such conditions, the effect (synergistic effect) produced by the coexistence of the first carbon fiber 11 and the second carbon fiber 12 is more significantly exerted.

The content rate of carbon fiber 1 in the carbon fiber sheet 100 (the sum of the content rate of the first carbon fiber 11 and the content rate of the second carbon fiber 12) is preferably 50 mass% or more and 99.5 mass% or less. More preferably, it is 54 mass % or more and 99 mass % or less, and still more preferably, it is 63 mass % or more and 98.5 mass % or less.

By satisfying such conditions, the characteristics of the carbon fiber 1 can be brought out more effectively, and the strength, reliability, etc. of the carbon fiber sheet 100 or the molded article can be made more excellent.

(adhesive)

The binder 20 has a function of connecting the carbon fibers 1 (the first carbon fibers 11 and the second carbon fibers 12). In addition, when the adhesive 20 remains in the molded body produced using the carbon fiber sheet 100, it may also constitute a part of the matrix resin in the molded body.

In addition, the adhesive 20 may directly connect the carbon fibers 1 or may connect the carbon fibers 1 to each other through other components (such as attachments 2 or other components described below).

Examples of the adhesive 20 include polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polylactic acid (PLA), etc. polyester); polyolefins (polyolefins) such as polyethylene (PE) and polypropylene (PP); polyamides (polyamides) such as nylon 6 (nylon 6) and nylon 6,6 (nylon 6/6); Polyvinyl alcohol (PVA), poly Thermoplastic resins such as vinyl acetate (PVAc), polyphenylene sulfide (PPS), polyetherketone, polycarbonate, phenoxy resin, etc.; epoxy resin Thermohardening resins such as epoxy resin, phenol resin, melamine resin, unsaturated polyester, or their copolymers, or modified resins , polymer alloy, etc., and one or more of them can be selected for use in combination.

Among them, the adhesive 20 is preferably polyvinyl alcohol.

Thereby, the adhesive 20 can more appropriately connect and fix the carbon fibers 1 to each other, and can provide the carbon fiber sheet 100 with appropriate drape properties.

The content of the binder 20 in the carbon fiber sheet 100 is preferably 0.5 mass% or more and 50 mass% or less, more preferably 1.0 mass% or more and 45 mass% or less, still more preferably 1.5 mass% or more. 35% by mass or less.

By satisfying such conditions, the characteristics of the carbon fiber 1 can be brought out more effectively, and the strength, reliability, etc. of the carbon fiber sheet 100 or the molded article can be made more excellent.

(other ingredients)

The carbon fiber sheet 100 may contain components other than those mentioned above (other components).

Examples of such a series of ingredients include plasticizers, colorants, antioxidants, ultraviolet absorbers, Light stabilizer, softener, modifier, antirust, filler, surface lubricant, corrosion inhibitor, heat-resistant stabilizer, lubricant, primer, antistatic agent, polymerization Polymerization inhibitor, cross-linking agent, catalyst, leveling agent, viscous agent, dispersant, anti-aging agent, flame retardant , anti-hydrolysis agent, carbon nanotube (CNT), carbon nanofiber, cellulose nanofiber, fullerene, graphite, etc.

Although the thickness of the carbon fiber sheet 100 is not particularly limited, it is preferably not less than 0.15 mm and not more than 2.5 mm, more preferably not less than 0.20 mm and not more than 2.0 mm, still more preferably not less than 0.25 mm and not more than 1.5 mm.

This makes it possible to further improve the ease of handling of the carbon fiber sheet 100, the ease of manufacturing the prepreg 200 and the like, and the formability when forming a molded article.

The use of the carbon fiber sheet 100 is not particularly limited. It can be used, for example, in the manufacture of prepregs or formed bodies described below, or as heat sinks (fins), thermal conductive sheets, or electromagnetic shielding materials. , electrode materials, etc.

[Prepreg]

Next, the prepreg material of the present invention will be described.

The prepreg material of the present invention is a sheet-like member that can be used for pre-shaping by heating and pressing. Manufacture of a shaped body, and includes first carbon fibers of original carbon fibers and second carbon fibers of recycled carbon fibers, and includes a resin material. The resin material may be either thermoplastic resin or thermosetting resin. In addition, in the present invention, the concept of semi-preg (semipreg) in which the resin material is not completely impregnated is also included in the prepreg.

<Implementation Pattern 1>

FIG. 3 is a schematic top view showing Embodiment 1 of the prepreg material of the present invention.

The prepreg material 200 of this embodiment is formed by impregnating the carbon fiber sheet 100 with the resin material (impregnated resin) 30 .

This makes it possible to provide the prepreg 200 that can be used to produce a molded article excellent in strength and reliability with excellent formability.

In addition, since excellent formability is obtained during the production of the molded article, the production conditions (for example, temperature, pressure, etc.) of the molded article can be relaxed. This makes it possible to use an object with a simple structure as a manufacturing device, or to suppress the load on the manufacturing device to extend the life of the manufacturing device. Furthermore, it is also advantageous from the viewpoint of suppressing the production cost of the molded body.

In addition, since excellent formability can be maintained even if the content rate of carbon fiber is increased, the content rate of the resin material can be reduced, so that the excellent properties of carbon fiber (such as strength and thermal conductivity) can be more effectively exhibited in the molded article. properties, conductivity, etc.).

In addition, by using the recycled second carbon fiber 12, it is also preferable from the viewpoints of saving resources and reducing environmental load.

In addition, the resin material (impregnated resin) 30 constitutes the matrix resin in the molded body.

As the resin material (impregnated resin) 30, the series includes polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polylactic acid; polyolefins such as polyethylene and polypropylene; nylon 6, nylon Polyamides such as 6 and 6; thermoplastic resins such as polyvinyl alcohol (PVA), polyvinyl acetate, polyphenylene sulfide, polyetherketone, polycarbonate, phenoxy resin; epoxy resin, phenolic resin, melamine Resins, thermosetting resins such as unsaturated polyester, or copolymers thereof, or modified resins, polymer alloys, etc., and one or more of them may be selected and used in combination.

Among them, the resin material (impregnated resin) 30 is preferably a thermosetting resin.

Thereby, the strength, durability, etc. of the molded body can be made particularly excellent.

The content rate of the resin material (impregnated resin) 30 in the prepreg 200 is preferably 3.0 mass% or more and 70 mass% or less, more preferably 4.0 mass% or more and 68 mass% or less, and still more preferably 5.0 mass% or more. More than 65% by mass and less than 65% by mass.

By satisfying such conditions, the strength and reliability of the molded body produced using the prepreg material 200 can be greatly improved, and at the same time, the formability of the molded body can be further improved.

The content rate of the carbon fiber 1 in the prepreg 200 (the sum of the content rate of the first carbon fiber 11 and the content rate of the second carbon fiber 12) is preferably 16 mass % or more and 96 mass % or less, more preferably The earth system should be 17.5 mass% or more and 95 mass% or less, and even better, the earth system should be 23 mass% or more and 93 mass% or less.

By satisfying such conditions, the characteristics of the carbon fiber 1 itself can be brought out more effectively, and the strength and reliability of the molded body produced using the prepreg material 200 can be greatly improved, and at the same time, the manufacturing process can be improved. The formability of the molded body becomes even better.

Furthermore, assuming that the content rate of the carbon fiber 1 in the prepreg material 200 (the sum of the content rate of the first carbon fiber 11 and the content rate of the second carbon fiber 12) is X _CF [mass %], the prepreg material 200 _{When the} content rate of the resin material (impregnated _resin ) 30 in ₂₀₀ is /X _CF ≦3.8; more preferably, it is a relation satisfying 0.055≦X _IR /X _CF ≦2.8.

By satisfying such conditions, the characteristics of the carbon fiber 1 itself can be brought out more effectively, and the strength and reliability of the molded body produced using the prepreg material 200 can be greatly improved, and at the same time, the manufacturing process can be improved. The formability of the molded body becomes even better.

The prepreg 200 may contain components other than those mentioned above (other components).

Examples of such a series of ingredients include plasticizers, colorants, antioxidants, ultraviolet absorbers, light stabilizers, softeners, modifiers, anti-rust agents, fillers, surface lubricants, anti-corrosion agents, anti-corrosion agents, etc. Thermal stabilizer, lubricant, primer, antistatic agent, polymerization inhibitor, cross-linking agent, catalyst, leveling agent, tackifier, dispersant, anti-aging agent, flame retardant, anti-hydrolysis agent, nanometer Carbon tubes, nanocarbon fibers, nanocellulose, fullerene, graphite, etc.

Although the thickness of the prepreg 200 is not particularly limited, it is preferably 0.15 mm or more and 2.5 mm or less, more preferably 0.20 mm or more and 2.0 mm or less, and still more preferably 0.25 mm or more and 1.5 mm or less.

Thereby, the prepreg material 200 can be made more excellent in ease of handling, ease of manufacture, formability when it is formed into a molded article, and the like.

<Implementation Pattern 2>

FIG. 4 is a schematic top view showing Embodiment 2 of the prepreg material of the present invention. In the following description, differences from the aforementioned embodiments will be mainly described, and descriptions of the same matters will be omitted.

The prepreg material 200 in this embodiment includes a plurality of carbon fibers 1 , a plurality of resin fibers 40 , and an adhesive 20 used to connect the carbon fibers 1 and the resin fibers 40 . Next, the carbon fibers 1 include the first carbon fibers 11 of original carbon fibers and the second carbon fibers 12 of recycled carbon fibers.

Thereby, the prepreg material 200 which can be used for manufacturing the molded object excellent in strength and reliability with excellent formability can be provided.

In addition, since excellent formability is obtained during the production of the molded article, the production conditions (for example, temperature, pressure, etc.) of the molded article can be relaxed. This makes it possible to use an object with a simple structure as a manufacturing device, or to suppress the load on the manufacturing device to extend the life of the manufacturing device. Furthermore, it is also advantageous from the viewpoint of suppressing the production cost of the molded body.

In addition, since excellent formability can be maintained even if the content rate of carbon fiber is increased, the content rate of the resin material can be reduced, so that the excellent properties of carbon fiber (such as strength and thermal conductivity) can be more effectively exhibited in the molded article. properties, conductivity, etc.).

In addition, by using the recycled second carbon fiber 12, it is also preferable from the viewpoints of saving resources and reducing environmental load.

In addition, the resin fiber 40 constitutes the matrix resin in the molded body.

In addition, in the prepreg material 200 of this embodiment, regarding the carbon fiber 1 (the first carbon fiber 11, the second carbon fiber 12), the attachment 2, and the adhesive 20, conditions other than those described below are The conditions are preferably the same as those described for the carbon fiber sheet 100 .

As the constituent materials of the resin fiber 40, the series includes polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polylactic acid; polyolefins such as polyethylene and polypropylene; nylon 6, nylon 6, Polyamides such as 6; polyetherketone (polyetherketone; PEEK) and other polyetherketones; polyvinyl acetate, polyphenylene sulfide, polycarbonate, polystyrene Thermoplastics such as (polystyrene), acrylonitrile-butadiene-styrene resin (ABS resin), polyvinyl chloride resin (PVC resin), phenoxy resin, etc. Resin; epoxy resin, phenolic resin, melamine resin, unsaturated polyester and other thermosetting resins, or their copolymers, or modified resins, polymer alloys, etc., and you can choose one or a combination of two or more from these use.

Among them, as the constituent material of the resin fiber 40, polypropylene, polycarbonate, polyamide, polyetheretherketone, and polyphenylene sulfide are preferred.

This makes the prepreg material 200 easier to handle and can achieve a higher level of both the formability and the characteristics of the molded object (strength, reliability, etc.) during manufacturing.

Although the average length of the resin fiber 40 is not particularly limited, it is preferably not less than 2.0 mm and not more than 20 mm, more preferably not less than 3.0 mm and not more than 18 mm, still more preferably not less than 4.0 mm and not more than 16 mm.

This makes it possible to further improve the ease of handling of the prepreg material 200, the strength and reliability of the molded object produced using the prepreg material 200, and the formability during the production of the molded object.

When the average length of the carbon fiber 1 is L _CF [mm] and the average length of the resin fiber 40 is L _RF [mm], it is preferable to satisfy the relational expression of 0.10≦L _RF /L _CF ≦18, and more preferably The earth system satisfies the relational expression of 0.25≦L _RF /L _CF ≦11, and even better, the earth system satisfies the relational expression of 0.45≦L _RF /L _CF ≦7.0.

This makes it possible to further improve the ease of handling of the prepreg material 200, the strength and reliability of the molded object produced using the prepreg material 200, and the formability during the production of the molded object.

The content rate of the carbon fiber 1 in the prepreg 200 (the sum of the content rate of the first carbon fiber 11 and the content rate of the second carbon fiber 12) is preferably 16 mass % or more and 96 mass % or less, more preferably The earth system should be 17.5 mass% or more and 95 mass% or less, and even better, the earth system should be 23 mass% or more and 93 mass% or less.

By satisfying such conditions, the characteristics of the carbon fiber 1 itself can be brought out more effectively, and the strength and reliability of the molded body produced using the prepreg material 200 can be greatly improved, and at the same time, the manufacturing process can be improved. The formability of the molded body becomes even better.

When the content rate of the first carbon fiber 11 in the prepreg 200 is X _VCF [mass %] and the content rate of the second carbon fiber 12 is X _RCF [mass %], it is preferable to satisfy 0.006≦X _{VCF / _ _ _ _}

By satisfying such conditions, the characteristics of the carbon fiber 1 itself can be brought out more effectively, and the strength and reliability of the molded body produced using the prepreg material 200 can be greatly improved, and at the same time, the manufacturing process can be improved. The formability of the molded body becomes even better.

The content rate of the binder 20 in the prepreg 200 is preferably 0.2 mass% or more and 20 mass% or less, more preferably 0.3 mass% or more and 15 mass% or less, still more preferably 0.6 mass% or more and 10 mass% or more. mass% or less.

This makes it possible to further improve the ease of handling of the prepreg material 200, the strength and reliability of the molded object produced using the prepreg material 200, and the formability during the production of the molded object.

The content rate of the resin fiber 40 in the prepreg material 200 is preferably 3.0 mass% or more and 75 mass% or less, more preferably 4.0 mass% or more and 72 mass% or less, still more preferably 5.0 mass% or more and 70 mass% or more. mass% or less.

This makes it possible to further improve the ease of handling of the prepreg material 200, the strength and reliability of the molded object produced using the prepreg material 200, and the formability during the production of the molded object.

Let the content rate of the carbon fiber 1 in the prepreg 200 (the sum of the content rate of the first carbon fiber 11 and the content rate of the second carbon fiber 12) be X _CF [mass %], and let the content rate of the resin fiber 40 be _{When it is _ _} Satisfies the relational expression 0.50≦X _CF /X _RF ≦15.

By satisfying such conditions, the characteristics of the carbon fiber 1 itself can be brought out more effectively, and the strength and reliability of the molded body produced using the prepreg material 200 can be greatly improved, and at the same time, the manufacturing process can be improved. The formability of the molded body becomes even better.

The prepreg 200 may contain components other than those mentioned above (other components).

Examples of such a series of ingredients include plasticizers, colorants, antioxidants, ultraviolet absorbers, light stabilizers, softeners, modifiers, rust inhibitors, fillers, surface lubricants, corrosion inhibitors, heat-resistant stabilizers, and lubricants. Agent, primer, antistatic agent, polymerization inhibitor, cross-linking agent, catalyst, leveling agent, tackifier, dispersant, anti-aging agent, flame retardant, anti-hydrolysis agent, carbon nanotube, nanometer Carbon fiber, nanocellulose, fullerene, graphite, etc.

Furthermore, the resin material (impregnated resin) described in the above-mentioned Embodiment 1 may be impregnated into the gaps between the fibers.

[molded body]

Next, the molded article of the present invention will be described.

The forming system of the present invention is formed by heating and pressurizing the prepreg material of the present invention.

Thereby, a molded body excellent in strength and reliability can be provided.

The molding system of the present invention only needs to have a portion formed by heating and pressurizing the prepreg of the present invention, and may further have a structure such as a coating film.

Although the molded article of the present invention can be used for any purpose, examples of uses of the molded article of the present invention include structural members of vehicles (such as cars, bicycles, trains, airplanes, rockets, elevators, etc.), Components of electronic and electrical parts (such as personal computers, mobile phones (including smartphones, PHS (Personal Handy Phone), etc.), tablets, etc.) Body parts for terminals, etc.), components for buildings and civil structures, furniture, etc.

[Manufacturing method of carbon fiber sheet]

Next, the method for manufacturing the carbon fiber sheet of the present invention will be described.

The carbon fiber sheet 100 may be made of, for example, a first carbon fiber 11 of original carbon fiber, a second carbon fiber 12 of recycled carbon fiber, and a carbon fiber for connecting the first carbon fiber 11 and the second carbon fiber 12. The adhesive 20 is produced by performing a mixing step (papermaking step).

This provides a method for manufacturing the carbon fiber sheet 100 that can stably produce the carbon fiber sheet 100 that is excellent in strength and reliability and can be used to produce a molded body that is excellent in strength and reliability with excellent formability.

In the papermaking step, at least a part of the surface of the carbon fiber 1 (the first carbon fiber 11 and the second carbon fiber 12) may be treated with a sizing agent or the like.

Thereby, the adhesion with resin materials such as the adhesive 20 can be improved, and the strength and reliability of the carbon fiber sheet 100 or the molded body can be improved.

Examples of the sizing agent series include epoxy resin, phenolic resin, polyethyleneglycol, polyurethane, polyester, emulsifiers, surfactants, etc.

Although the content rate of the carbon fiber 1 in the composition for papermaking is not particularly limited (the sum of the content rate of the first carbon fiber 11 and the content rate of the second carbon fiber 12), by making it 0.01 mass % or more and 0.3 mass % % or less, the bundled body 10 as mentioned above can be formed very efficiently.

[Manufacturing method of prepreg]

Next, the manufacturing method of the prepreg material of this invention is demonstrated.

<Implementation Pattern 1>

The prepreg 200 of the above-mentioned Embodiment 1 is stabilized by, for example, a method having a step (impregnation step) of impregnating the resin material (impregnating resin) 30 into the carbon fiber sheet 100 obtained through the paper-making step. manufactured locally.

The series of impregnation steps includes, for example, thermal transfer of a sheet made of a material containing thermosetting resin or thermoplastic resin in an uncured state (B stage) as the resin material (impregnated resin) 30 . ) to the carbon fiber sheet 100, or a method of impregnating the carbon fiber sheet 100 with a liquid resin material (impregnated resin) 30, etc.

<Implementation Pattern 2>

The prepreg material 200 of the aforementioned embodiment 2 uses, for example, the first carbon fiber 11 of the original carbon fiber, the second carbon fiber 12 of the recycled carbon fiber, the resin fiber 40, and the first carbon fiber 11 for connecting. The second carbon fiber 12 and the binder 20 of the resin fiber 40 are mixed together (papermaking step) to be stably produced.

Furthermore, in the manufacturing method of Embodiment 1 described above, the carbon fiber sheet 100 obtained through the papermaking step is impregnated. In contrast, in the manufacturing method of this embodiment, the carbon fiber sheet 100 obtained through the papermaking step is impregnated. The carbon fiber 1 (the first carbon fiber 11 and the second carbon fiber 12), the resin fiber 40, and the adhesive 20 are used without the subsequent impregnation step. Therefore, the productivity of the prepreg 200 can be improved.

[Method for manufacturing molded body]

Next, the manufacturing method of the molded body of this invention is demonstrated.

The above-described molding system can be stably produced using, for example, a method including a step (forming step) of subjecting the prepreg 200 produced as described above to heat and pressure molding.

When manufacturing a molded body, a plurality of prepregs 200 may be laminated.

Although the number of laminated sheets is not particularly limited, it is preferably from 2 to 50 sheets, and more preferably from 3 to 30 sheets.

In addition, when a plurality of prepregs 200 are used, the prepregs 200 may be prepregs 200 with different conditions, or may be prepregs 200 with the same condition.

Furthermore, an intermediate layer may be provided between adjacent prepregs 200 .

In addition, before the joining step, a process of joining a plurality of prepregs 200 may be performed. Examples of a series of methods for joining a plurality of prepregs 200 include dissolution (including solvent dissolution, polymerization). melting, etc.), melting, sticking, etc.

The heating temperature in the molding step varies depending on the type, content rate, etc. of the resin material (impregnated resin) 30 or resin fiber 40. Although it is not particularly limited, it is preferably 100°C or more and 380°C or less, more preferably Preferably, the temperature is above 110°C and below 350°C, and more preferably, it is above 120°C and below 300°C.

In addition, the molding pressure in the molding step varies depending on the type, content rate, etc. of the resin material (impregnated resin) 30 or resin fiber 40. Although it is not particularly limited, it is preferably 0.1 MPa or more and 15 MPa or less. More preferably, it is 0.2MPa or more and 12MPa or less, and still more preferably, it is 0.3MPa or more and 10MPa or less.

When the prepreg 200 includes a thermosetting resin, the curing reaction of the thermosetting resin proceeds through heating in the molding step, so that the obtained molded article also becomes excellent in heat resistance and the like.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these.

For example, in the method of manufacturing a carbon fiber sheet, the method of manufacturing a prepreg, and the method of manufacturing a molded body, in addition to the above-mentioned steps, other steps (pre-processing step, intermediate processing step, post-processing step) may also be included. wait).

In addition, the carbon fiber sheet, prepreg, and molding system of the present invention are not limited to those produced by the above-mentioned method, and may be produced by any method.

In addition, in the above-mentioned embodiments, the carbon fiber sheets, prepregs, and molded bodies are represented by structures including carbon fibers that do not constitute the bundled body in addition to the carbon fibers constituting the bundled body. has been described above, but it may be a composition including only one of them.

[Example]

Although the present invention will be described in detail below based on Examples and Comparative Examples, the present invention is not limited to these. In addition, processing and measurement where temperature conditions are not specified are performed at 20°C.

《1》Manufacturing of carbon fiber sheets

The carbon fiber sheets of each example and each comparative example were produced in the following manner.

(Example A1)

First, 20 parts by mass of original carbon fiber (first carbon fiber: average fiber diameter (average width) 7.0 μm, average length 6.0 mm) and recovered carbon fiber (second carbon fiber: average fiber diameter (average width) 7.0 μm, average length 5.0 mm): 75 parts by mass, and polyvinyl alcohol fiber used as a binder (fineness: 1.1 dtex, average length 3.0 mm, weighted average density) : 1.20g/cm ³ ): A composition consisting of 5.0 parts by mass is mixed and dispersed in water to prepare a slurry for papermaking with a solid content of 0.03% by mass.

Next, 0.001 parts by mass of anionic polyacrylamide as a dispersant was added to 100 parts by mass of the papermaking slurry to obtain a dispersion, and the dispersion was adsorbed in the gaps of the mesh. It is deposited on the papermaking surface of the 0.2mm mesh conveyor to form a sheet (papermaking step).

Thereafter, the sheet in a humidified state produced in the papermaking step is heated and dried at 120° C., and the polyvinyl alcohol fibers are melted and the carbon fibers are connected through intersection points to obtain a carbon fiber sheet.

In addition, as the recovered carbon fibers, those obtained by subjecting crushed or pulverized CFRP to a first heat treatment at 350°C in an air atmosphere, and further subjecting a second heat treatment to 550°C in an air atmosphere were used. of carbon fiber.

(Example A2, Example A3)

A carbon fiber sheet was produced in the same manner as in Example A1 except that the conditions of the first carbon fiber, the second carbon fiber, and the binder were changed to those shown in Table 1.

(Comparative example A1)

A carbon fiber sheet was produced in the same manner as in Example A1 except that only the first carbon fiber was used as the carbon fiber and the mixing ratio of each component was as shown in Table 1.

(Comparative example A2)

A carbon fiber sheet was produced in the same manner as in Example A1 except that only the second carbon fiber was used as the carbon fiber and the mixing ratio of each component was as shown in Table 1.

Table 1 shows the composition of the carbon fiber sheets of each of the aforementioned Examples and Comparative Examples. In addition, the second carbon fiber used in each of the above-described examples and Comparative Example A2 has adhesion derived from recycled raw materials adhered to a part of its surface. Moreover, the carbon fiber sheet of each of the above-mentioned Examples and Comparative Example A2 includes bundles containing a plurality of carbon fibers, and also includes carbon fibers that do not constitute bundles. Furthermore, the thickness of the carbon fiber sheets in each of the above-mentioned examples and comparative examples is 0.5 mm or more and 0.8 mm or less.

《2》Manufacturing of prepreg materials

The prepreg materials of each Example and each Comparative Example were produced in the following manner.

(Example B1)

First, a methanol (methanol) solution (40% by mass) of a phenolic resin, which is an uncured thermosetting resin, was prepared.

Next, the methanol solution was applied to the carbon fiber sheet of the aforementioned Example A1 to impregnate it. Thereafter, it was heated to 80° C. to remove methanol, and further heat treatment was performed at 150° C. for 15 minutes to harden the phenolic resin to obtain a prepreg.

(Example B2, Example B3)

The carbon fiber sheet was produced in the same manner as in Example B1, except that the carbon fiber sheet produced in Example A2 and Example A3 was used as the carbon fiber sheet instead of the carbon fiber sheet produced in Example A1. prepreg material.

(Example B4)

First, original carbon fiber (first carbon fiber: average fiber diameter (average width) 7.0 μm, average length 6.0 mm): 5.0 parts by mass, recovered carbon fiber (second carbon fiber: average fiber diameter (average width) 7.0 μm, average length 5.0 mm): 35.2 parts by mass, polyvinyl alcohol fiber used as a binder (density 1.1 dtex, average length 3.0 mm, weighted average density: 1.20 g/cm ³ ): 2.9 A composition consisting of 56.9 parts by mass and 56.9 parts by mass of nylon 6 fiber (density 1.1 dtex, average length 6.0 mm) as resin fiber was mixed and dispersed in water to prepare a papermaking slurry with a solid content of 0.03% by mass.

Next, 0.001 parts by mass of anionic polyacrylamide as a dispersant was added to 100 parts by mass of the papermaking slurry to obtain a dispersion, and the dispersion was adsorbed on a mesh conveyor with a mesh gap of 0.3 mm. They are accumulated on the papermaking surface to form a sheet (papermaking step).

Thereafter, the humidified sheet produced in the papermaking step was heated and dried at 120°C, and the polyvinyl alcohol fibers were melted and the carbon fibers were connected through intersections to obtain a prepreg. In the obtained prepreg, the nylon 6 fibers are not melted and remain in the fiber state.

In addition, as the recovered carbon fibers, those obtained by subjecting crushed or pulverized CFRP to a first heat treatment at 350°C in an air atmosphere, and further subjecting a second heat treatment to 550°C in an air atmosphere were used. of carbon fiber.

(Example B5, Example B6)

A prepreg was produced in the same manner as in Example B4 except that the conditions of the first carbon fiber, the second carbon fiber, the binder, and the resin fiber were changed to those shown in Table 2.

(Comparative Example B1, Comparative Example B2)

It was produced in the same manner as in Example B1 except that the carbon fiber sheet produced in Comparative Example A1 and Comparative Example A2 was used as the carbon fiber sheet instead of the carbon fiber sheet produced in Example A1. prepreg material.

(Comparative example B3)

A prepreg was produced in the same manner as in Example B4 except that only the first carbon fiber was used as the carbon fiber and the mixing ratio of each component was as shown in Table 2.

(Comparative example B4)

A prepreg was produced in the same manner as in Example B4 except that only the second carbon fiber was used as the carbon fiber and the mixing ratio of each component was as shown in Table 2.

Table 2 shows the composition of the prepreg materials of each of the above-mentioned Examples and Comparative Examples. In addition, the second carbon fiber used in each of the above-mentioned Examples and Comparative Examples B2 and Comparative Examples B4 has adhesion derived from recycled raw materials adhered to a part of its surface. In addition, the prepreg materials of each of the above-described Examples and Comparative Examples B2 and B4 include bundles containing a plurality of carbon fibers, and carbon fibers that do not constitute bundles are also included. Furthermore, the thickness of the prepreg materials in each of the above-mentioned examples and comparative examples is 0.8 mm or more and 1.4 mm or less.

《3》Manufacture of formed bodies

The molding systems of each Example and each Comparative Example were produced in the following manner.

(Example C1)

First, 15 sheets of the prepreg produced in the above-mentioned Example B1 were laminated.

Next, the prepreg laminate was heated and pressurized under conditions of 50 kg/cm ² and 150°C. Thereby, the thermosetting resin contained in the prepreg is hardened, and a flat-plate shaped body A is obtained in which the layers of the prepreg are connected to each other.

Furthermore, a molded body B was produced in the same manner as the above-mentioned molded body A, except that the molded body was formed into a curved plate having an L-shaped curvature radius of the outer peripheral surface.

(Example C2, Example C3)

A molded body was produced in the same manner as in Example C1, except that the prepregs produced in Examples B2 and B3 were used instead of the prepregs produced in Example B1. (Molded object A and molded object B).

(Example C4)

First, 15 sheets of the prepreg produced in the above-mentioned Example B4 were laminated.

Next, the prepreg laminate was heated and pressurized under conditions of 50 kg/cm ² and 250°C. Thereby, the thermoplastic resin contained in the prepreg material is softened and melted, and a flat-plate shaped body A is obtained in which the layers of the prepreg material are connected to each other.

Furthermore, a molded body B was produced in the same manner as the above-mentioned molded body A, except that the molded body was formed into a curved plate having an L-shaped curvature radius of the outer peripheral surface.

(Example C5, Example C6)

A molded body was produced in the same manner as in Example C4, except that the prepregs produced in Examples B5 and B6 were used instead of the prepregs produced in Example B4. (Molded object A and molded object B).

(Comparative Example C1, Comparative Example C2)

A molded body was produced in the same manner as in Example C1, except that the prepregs produced in Comparative Examples B1 and B2 were used instead of the prepregs produced in Example B1. (Molded object A and molded object B).

(Comparative Example C3, Comparative Example C4)

A molded body was produced in the same manner as in Example C4, except that the prepregs produced in Comparative Examples B3 and B4 were used instead of the prepregs produced in Example B5. (Molded object A and molded object B).

In addition, the molded articles of each of the above-described Examples and Comparative Examples C2 and C4 include bundles containing a plurality of carbon fibers, and carbon fibers that do not constitute bundles are also included.

"4" review

《4-1》Bending strength evaluation

The required bending strength of the molded bodies A of Examples C1 to C6 and Comparative Examples C1 to C4 was measured by a bending test in compliance with the standards of JIS K7074, and the evaluation was carried out in accordance with the following standards.

A: The bending strength is above 250MPa.

B: The bending strength is more than 200MPa and less than 250MPa.

C: The bending strength is more than 150MPa and less than 200MPa.

D: The bending strength is more than 100MPa and less than 150MPa.

E: Bending strength is less than 100MPa.

"4-2" appearance evaluation

(Visual evaluation)

The molded bodies B of Examples C1 to C6 and Comparative Examples C1 to C4 were visually observed and evaluated based on the following standards.

A: No appearance defects were detected at all.

B: Almost no appearance defect was recognized.

C: Some appearance defects are recognized.

D: The exact appearance defect is recognized.

E: Significant appearance defect is recognized.

(Evaluation of Microscope)

The vicinity of the bent portion of the molded body B of Examples C1 to C6 and Comparative Examples C1 to C4 was observed through a microscope and evaluated based on the following standards.

A: Uneven amount of carbon fiber exposure was not recognized.

B: Coexistence of areas with a large amount of carbon fiber exposure and areas with a small amount of carbon fiber exposure but a large amount of resin material, and slight unevenness in the amount of carbon fiber exposure were recognized.

C: The coexistence of an area with a large amount of exposed carbon fiber and an area with a small amount of exposed carbon fiber but a large amount of resin material, and the exact unevenness of the amount of exposed carbon fiber, are recognized.

D: Coexistence of an area with a large amount of exposed carbon fiber and an area with a small amount of exposed carbon fiber but a large amount of resin material, and significant uneven exposure of the carbon fiber, were recognized.

The results are summarized and shown in Table 3.

As is apparent from Table 3, excellent results were obtained in the present invention, but satisfactory results were not obtained in the comparative examples.

[Industrial availability]

The carbon fiber sheet of the present invention includes a plurality of carbon fibers and a binder used to connect the aforementioned carbon fibers, and as the aforementioned carbon fibers, it includes a first carbon fiber of original carbon fiber and a second carbon fiber of recycled carbon fiber. fiber. Thereby, it is possible to provide a carbon fiber sheet that is excellent in its own strength and reliability and can be used to produce a molded article that is excellent in strength and reliability with excellent formability. Therefore, the carbon fiber sheet of the present invention has industrial applicability.

1, 11, 12: Carbon fiber

2: Attachments

10: fascicle

20: Adhesive

100: Carbon fiber sheet

Claims (21)

A carbon fiber sheet, which includes: a plurality of carbon fibers; and a binder used to connect the aforementioned carbon fibers; wherein, as the aforementioned carbon fibers, it includes: a first carbon fiber, which is an original carbon fiber; and a second carbon fiber. Carbon fiber, which is recycled carbon fiber; the aforementioned second carbon fiber has an organic component derived from the recycled raw material of the second carbon fiber as an attachment attached to its surface and/or a carbonized product of the organic component; including through The attachments connect a plurality of the second carbon fibers into a bundled body; the coverage rate of the attachments on the surface of the second carbon fibers is 2% or more and 40% or less. The carbon fiber sheet according to claim 1, wherein the average length of the second carbon fibers is shorter than the average length of the first carbon fibers. The carbon fiber sheet according to claim 2, wherein the average length of the first carbon fiber is L _VCF [mm] and the average length of the second carbon fiber is L _RCF [mm], satisfying 1.1 ≦L _VCF /L _RCF ≦30 relationship. The carbon fiber sheet according to Claim 1, wherein the average length of the second carbon fiber is 1.0 mm or more and 10 mm or less. The carbon fiber sheet according to claim 1, wherein the first carbon fiber content is X _VCF [mass %] and the second carbon fiber content is X _RCF [mass %]. Satisfies the relationship expression of 0.006≦X _VCF /X _RCF ≦1.0. The carbon fiber sheet according to claim 1, wherein the aspect ratio relative to the length of the width of the bundled body is 2 to 500. A prepreg made by impregnating the carbon fiber sheet described in claim 1 with a resin material. A prepreg material, which includes: a plurality of carbon fibers; a plurality of resin fibers; and a binder used to connect the aforementioned carbon fibers and the aforementioned resin fibers; wherein, as the aforementioned carbon fibers, it includes: a first carbon fiber, which It is original carbon fiber; and the second carbon fiber is recycled carbon fiber; the aforementioned second carbon fiber has an organic component derived from the recycled raw material of the second carbon fiber as an attachment attached to its surface and/or The carbonized substance of the organic component includes a bundle in which a plurality of the second carbon fibers are connected into a bundle through the attachment; and the coverage rate of the attachment on the surface of the second carbon fiber is 2% or more and 40%. the following. The prepreg material according to claim 8, wherein the average length of the resin fibers is 2.0 mm or more and 20 mm or less. The prepreg material according to claim 8, wherein the carbon fiber content ratio is X _CF [mass %] and the resin fiber content ratio is X _RF [mass %], and 0.30≦ X _CF is satisfied. /X _RF ≦28 relationship. The prepreg material according to claim 8, wherein the average length of the carbon fiber is L _CF [mm] and the average length of the resin fiber is L _RF [mm], satisfying 0.10≦L _RF /L The relational expression of _CF ≦18. The prepreg material according to Claim 8, wherein the average length of the second carbon fibers is shorter than the average length of the first carbon fibers. The prepreg material according to Claim 12, wherein the average length of the first carbon fiber is L _VCF [mm] and the average length of the second carbon fiber is L _RCF [mm], and 1.1≦ is satisfied. The relationship expression of L _VCF /L _RCF ≦30. The prepreg material according to Claim 8, wherein the average length of the second carbon fibers is 1.0 mm or more and 10 mm or less. The prepreg material according to claim 8, wherein the content of the first carbon fiber is X _VCF [mass %] and the content of the second carbon fiber is X _RCF [mass %]. 0.006≦X _VCF /X _RCF ≦1.0. The prepreg material according to Claim 8, wherein the aspect ratio relative to the length of the width of the bundled body is 2 to 500. A formed body formed by heating and pressurizing the prepreg material described in claim 7. A method of manufacturing a carbon fiber sheet, which includes first carbon fiber of original carbon fiber, second carbon fiber of recycled carbon fiber, and a binder for connecting the first carbon fiber and the second carbon fiber. The step of carrying out mixing; the aforementioned second carbon fiber has an organic component derived from the recycled raw material of the second carbon fiber as an attachment attached to its surface and/or a carbonized product of the organic component; It includes a bundled body in which a plurality of second carbon fibers are connected into a bundle through the attachment; the coverage rate of the attachment on the surface of the second carbon fiber is 2% or more and 40% or less. A method for manufacturing a prepreg, which includes the step of impregnating a carbon fiber sheet produced using the method described in claim 18 with a resin material. A method of manufacturing a prepreg material, which has the following steps: first carbon fiber of original carbon fiber, second carbon fiber of recycled carbon fiber, resin fiber, and connecting the aforementioned first carbon fiber, the aforementioned second carbon fiber, and the step of mixing the binder of the resin fiber; the surface of the second carbon fiber is attached with an organic component derived from the recycled raw material of the second carbon fiber as an attachment and/or a carbonized product of the organic component; including A plurality of the second carbon fibers are connected to form a bundle through the attachment; the coverage rate of the attachment on the surface of the second carbon fiber is 2% or more and 40% or less. A method of manufacturing a molded article, which includes the step of heating and pressurizing a prepreg material produced using the method described in Claim 19.

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