JPWO2020040289A1 - Carbon fiber sheet material, prepreg, molded body, carbon fiber sheet material manufacturing method, prepreg manufacturing method and molded body manufacturing method - Google Patents

Abstract

The carbon fiber sheet material of the present invention is a carbon fiber sheet material containing a plurality of carbon fibers and a binder for binding the carbon fibers, and the carbon fibers are the first carbon fibers which are virgin carbon fibers. And a second carbon fiber, which is a recycled carbon fiber. When the average length of the first carbon fiber is LVCF [mm] and the average length of the second carbon fiber is LRCF [mm], the relationship of 1.1 ≦ LVCF / LRCF ≦ 30 is satisfied. Is preferable.

Description

The present invention relates to a carbon fiber sheet material, a prepreg, a molded product, a method for producing a carbon fiber sheet material, a method for producing a prepreg, and a method for producing a molded product.

Fiber reinforced sheet materials and fiber reinforced resin molded products using the same are used in various fields such as vehicles and aircraft. In particular, fiber reinforced plastic (FRP) can realize excellent strength that cannot be achieved by plastic alone because the plastic is reinforced by the reinforced fibers to be embedded.

Among them, carbon fiber reinforced plastics (CFRP) using carbon fibers having particularly excellent physical properties are attracting attention (see Patent Document 1).

In conventional CFRP, long carbon fibers are used in order to take advantage of the excellent physical properties of carbon fibers, and carbon fibers are often used as a woven fabric.

However, such CFRP has a problem that it is inferior in moldability when producing a molded product having a predetermined three-dimensional structure from a sheet material such as a prepreg. Further, in the manufactured molded product, the distribution of the fibers and the resin material is likely to be unintentionally varied. For example, in the vicinity of the surface of the molded product, a region where many carbon fibers are exposed and an exposed carbon fiber. There are cases where the amount is small and the area where the resin material is exposed coexists, and there is a problem that the local strength is lowered.

In addition, from the viewpoint of effective use of resources, carbon fiber is also required to be recycled.

However, in the past, when recycled carbon fiber was used, there was a problem that satisfactory strength and reliability could not be obtained.

Japanese Unexamined Patent Publication No. 2014-077209

An object of the present invention is to provide a molded product having excellent strength and reliability, and to provide a prepreg that can be used for producing a molded product having excellent strength and reliability with excellent moldability. To provide a carbon fiber sheet material which is excellent in its own strength and reliability and can be used for producing a molded product having excellent strength and reliability with excellent moldability, and stably producing these. The purpose is to provide a manufacturing method that can be used.

Such an object is achieved by the present invention described in the following (1) to (27).
(1) A carbon fiber sheet material containing a plurality of carbon fibers and a binder for binding the carbon fibers.
A carbon fiber sheet material containing, as the carbon fiber, a first carbon fiber which is a virgin carbon fiber and a second carbon fiber which is a recycled carbon fiber.

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

(3) When the average length of the first carbon fiber is _LVCF [mm] and the average length of the second carbon fiber is _LRCF [mm], 1.1 ≤ L _VCF / L _RCF ≤ The carbon fiber sheet material according to (2) above, which satisfies the relationship of 30.

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

(5) When 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 ≤ The carbon fiber sheet material according to any one of (1) to (4) above, which satisfies the relationship of 1.0.

(6) The second carbon fiber is obtained by adhering an organic component derived from a recycled raw material of the second carbon fiber and / or a carbide of the organic component as an deposit on the surface thereof (1) to the above. The carbon fiber sheet material according to any one of (5).

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

(8) The carbon fiber sheet material according to (6) or (7) above, which comprises a bundle-like body in which a plurality of the second carbon fibers are bonded by the deposit to form a bundle.

(9) The carbon fiber sheet material according to (8) above, wherein the aspect ratio, which is the ratio of the length to the width of the bundle, is 2 or more and 500 or less.

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

(11) A prepreg containing a plurality of carbon fibers, a plurality of resin fibers, the carbon fibers, and a binder for binding the resin fibers.
The prepreg is characterized by containing, as the carbon fiber, a first carbon fiber which is a virgin carbon fiber and a second carbon fiber which is a recycled carbon fiber.

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

(13) When the carbon fiber content is X _CF [mass%] and the resin fiber content is X _RF [mass%], _{the relationship of 0.30 ≤ X CF} / X _RF ≤ 28 is satisfied. The prepreg according to (11) or (12) above.

(14) When the average length of the carbon fibers is L _CF [mm] and the average length of the resin fibers is L _RF [mm], _{the relationship of 0.10 ≤ L RF} / L _CF ≤ 18 is satisfied. The prepreg according to any one of (11) to (13) above.

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

(16) When the average length of the first carbon fiber is _LVCF [mm] and the average length of the second carbon fiber is _LRCF [mm], 1.1 ≤ L _VCF / L _RCF ≤ The prepreg according to (15) above, which satisfies the relationship of 30.

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

(18) When 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 ≤ The prepreg according to any one of (11) to (17) above, which satisfies the relationship of 1.0.

(19) The second carbon fiber is obtained by adhering an organic component derived from a recycled raw material of the second carbon fiber and / or a carbide of the organic component as an deposit on the surface thereof (11) to the above. The prepreg according to any one of (18).

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

(21) The prepreg according to (19) or (20) above, which comprises a bundle-like body in which a plurality of the second carbon fibers are bonded by the deposit to form a bundle.

(22) The prepreg according to (21) above, wherein the aspect ratio, which is the ratio of the length to the width of the bundle, is 2 or more and 500 or less.

(23) A molded product obtained by heat-press molding the prepreg according to any one of (10) to (22) above.

(24) A mixed extract of a first carbon fiber which is a virgin carbon fiber, a second carbon fiber which is a recycled carbon fiber, and a binder that binds the first carbon fiber and the second carbon fiber. A method for producing a carbon fiber sheet material, which comprises a step of making a carbon fiber sheet material.

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

(26) A first carbon fiber which is a virgin carbon fiber, a second carbon fiber which is a recycled carbon fiber, a resin fiber, the first carbon fiber, the second carbon fiber and the resin. A method for producing prepreg, which comprises a step of mixing with a binder for binding fibers.

(27) A method for producing a molded product, which comprises a step of heat-press molding a prepreg produced by using the method according to (25) or (26) above.

According to the present invention, to provide a molded product having excellent strength and reliability, and to provide a prepreg that can be used for producing a molded product having excellent strength and reliability with excellent moldability. To provide a carbon fiber sheet material which is excellent in its own strength and reliability and can be used for producing a molded product having excellent strength and reliability with excellent moldability, and stably producing these. It is possible to provide a manufacturing method that can be used.

FIG. 1 is a plan view schematically showing a preferred embodiment of the carbon fiber sheet material of the present invention. FIG. 2 is a vertical cross-sectional view schematically showing a preferred embodiment of the carbon fiber sheet material of the present invention. FIG. 3 is a plan view schematically showing a first embodiment of the prepreg of the present invention. FIG. 4 is a plan view schematically showing a second embodiment of the prepreg of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail.
In the following description, members of the same or the same quality are shown with the same name and reference numeral, and detailed description thereof will be omitted as appropriate. Further, in the present specification, the term "sheet material" is used to include not only a single sheet material but also a laminated body in which these are laminated in a plurality of layers, a mat-like shape, and a lump-like shape.

[Carbon fiber sheet material]
First, the carbon fiber sheet material of the present invention will be described.

FIG. 1 is a plan view schematically showing a preferred embodiment of the carbon fiber sheet material of the present invention, and FIG. 2 is a vertical sectional view schematically showing a preferred embodiment of the carbon fiber sheet material of the present invention. .. In FIG. 2, the deposit 2 and the binder 20 are not shown.

The carbon fiber sheet material 100 includes a plurality of carbon fibers 1 and a binder 20 that binds the carbon fibers 1. The carbon fibers 1 include a first carbon fiber 11 which is a virgin carbon fiber and a second carbon fiber 12 which is a recycled carbon fiber.

With such a configuration, it is possible to provide the carbon fiber sheet material 100 having excellent strength and reliability. Further, such a carbon fiber sheet material 100 can be suitably used for producing a molded product having excellent strength and reliability with excellent moldability.

A more detailed explanation is as follows. That is, the strength and reliability of the carbon fiber sheet material 100 as a whole are improved by containing the first carbon fiber 11, which is a virgin carbon fiber having higher quality and less likely to deteriorate in quality. Therefore, the strength of the molded product produced by using the carbon fiber sheet material 100 can be made excellent. In addition, recycled carbon fibers generally have excellent affinity with resin materials such as binders, and are superior in processability and moldability of carbon fiber sheet materials as compared with the case of using virgin carbon fibers. Therefore, it is possible to preferably prevent the occurrence of defects in the molded product manufactured by using the carbon fiber sheet material, and it is possible to improve the reliability of the molded product. Further, since molding defects are unlikely to occur, it can be suitably applied to the production of a molded product having a fine structure or a molded product having a portion having a small radius of curvature. Further, in the recycled carbon fiber, in general, the broken portion formed at the time of recycling tends to be in a relatively rough state, and the fibers are liable to be entangled or caught, and also adhere to a resin material such as a binder 20. It tends to be excellent in nature. Further, the recycled carbon fiber can suitably control the adhesion amount (coverage) of the deposit 2, the constituent material, the formation of the bundle 10 having a predetermined shape, and the like, which will be described later, depending on the recycling conditions. Therefore, the quality of the carbon fiber sheet material 100, the molded product, and the like can be stably and easily improved.

Further, since excellent moldability can be obtained during the production of the molded product, the manufacturing conditions (for example, temperature, pressure, etc.) of the molded product can be relaxed. Therefore, it is possible to use a manufacturing apparatus having a simple structure, suppress the load on the manufacturing apparatus, and extend the life of the manufacturing apparatus. It is also advantageous from the viewpoint of suppressing the production cost of the molded product.

Further, even if the carbon fiber content is increased, the excellent moldability can be maintained, so that the resin material content can be lowered, and the excellent properties of the carbon fiber in the molded product can be reduced. (For example, strength, thermal conductivity, conductivity, etc.) can be exhibited more effectively.

It is also preferable to use the recycled second carbon fiber 12 from the viewpoint of resource saving and reduction of environmental load.

On the other hand, if the above conditions are not satisfied, the above excellent effect cannot be obtained.
For example, when only virgin carbon fiber is used as the carbon fiber and recycled carbon fiber is not used, the adhesion between the carbon fiber and the resin material such as a binder may be sufficiently excellent. It became difficult, and the formability of the carbon fiber sheet material and the prepreg produced by using the carbon fiber sheet material and the reliability of the carbon fiber sheet material and the molded body produced by using the carbon fiber sheet material were sufficiently improved. It is difficult to make it excellent.

Further, when only recycled carbon fiber is used as the carbon fiber and no virgin carbon fiber is used, the strength of the carbon fiber sheet and the molded product produced by using the carbon fiber sheet is sufficiently excellent. It is difficult to make it.

(First carbon fiber)
As described above, the carbon fiber sheet material 100 contains virgin carbon fibers (first carbon fibers 11) as the carbon fibers 1.

By including the first carbon fiber 11, which is a virgin carbon fiber having higher quality and less likely to deteriorate in quality, the strength and reliability of the carbon fiber sheet material 100 as a whole can be made excellent. Therefore, the strength of the molded product produced by using the carbon fiber sheet material 100 can be made excellent.

Further, by including the first carbon fiber 11 (virgin carbon fiber) together with the second carbon fiber 12 (recycled carbon fiber) described in detail later, for example, as compared with the case where the virgin carbon fiber is not used. Therefore, the ratio of the bundled body in which a plurality of carbon fibers are bonded to form a bundle and the carbon fibers not formed into a bundle, and the distribution of the lengths of the carbon fibers can be preferably adjusted. As a result, the characteristics of the carbon fiber sheet material 100 and the molded product can be suitably controlled.

The average length of the first carbon fibers 11 (the same applies to the prepreg 200 described later and the average length of the first carbon fibers 11 contained in the molded product) is preferably 1.5 mm or more and 30 mm or less. It is more preferably 0.0 mm or more and 20 mm or less, and further preferably 4.0 mm or more and 16 mm or less.

As a result, it is possible to more effectively prevent defects during molding while making the strength of the carbon fiber sheet material 100, the molded body, etc. more excellent, and the reliability of the carbon fiber sheet material 100, the molded body, etc. Can be made better.

In the present invention, as the average length of fibers, for example, 100 fibers contained in a randomly selected field of view of microscopic observation are randomly selected, and the average value of these lengths is adopted. Can be done. When 100 fibers are not included in one field of view, a total of 100 fibers are randomly sampled in a plurality of different fields of view, and the average value of these lengths is adopted as the average length. be able to.

The average width of the first carbon fibers 11 (the same applies to the prepreg 200 described later and the average width of the first carbon fibers 11 contained in the molded product) is preferably 1.0 μm or more and 20 μm or less, preferably 2.0 μm. It is more preferably 18 μm or less, and further preferably 3.0 μm or more and 15 μm or less.

As a result, the strength of the carbon fiber sheet material 100 and the molded body can be made sufficiently excellent, and the processability and moldability of the carbon fiber sheet material 100 and the like can be made particularly excellent. In addition, it is possible to more effectively prevent undesired irregularities from being generated on the surface of the carbon fiber sheet material 100, the molded product, or the like.

In the present specification, as the average width of the fibers, for example, 100 fibers contained in a randomly selected field of view of microscopic observation may be randomly selected, and the average value of these widths may be adopted. can. If 100 fibers are not included in one field of view, a total of 100 fibers may be randomly sampled in a plurality of different fields of view, and the average value of these widths may be adopted as the average width. can.

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

By satisfying such a condition, the effect (synergistic effect) due to the coexistence of the first carbon fiber 11 and the second carbon fiber 12 is exhibited more remarkably.

As the first carbon fiber 11, a plurality of types of carbon fibers produced under different conditions may be used.

(Second carbon fiber)
As described above, the carbon fiber sheet material 100 contains the carbon fiber (second carbon fiber 12) recycled as the carbon fiber 1.

The average length of the second carbon fiber 12 is not particularly limited, but is preferably shorter than the average length of the first carbon fiber 11.

As a result, the moldability of the carbon fiber sheet material 100, the prepreg, and the like can be made more excellent. In addition, it is possible to more effectively prevent the occurrence of defects during molding (for example, local decrease in strength due to unintentional variation in distribution between fibers and resin material, poor appearance, etc.). Further, since molding defects are unlikely to occur, it can be more preferably applied to the production of a molded product having a fine structure or a molded product having a portion having a small radius of curvature.

When the average length of the first carbon fiber 11 is _LVCF [mm] and the average length of the second carbon fiber 12 is _LRCF [mm], the relationship of _{1.1 ≤ L VCF} / L _{RCF ≤ 30.} It is preferable _{to satisfy the relationship of 1.3 ≤ L VCF} / L _RCF ≤ 12, and it is further preferable to satisfy the relationship of 1.8 ≤ L _VCF / L _RCF ≤ 7.0. ..

As a result, the above-mentioned effects can be exhibited more remarkably, and the strength of the carbon fiber sheet material 100, the molded product, and the like can be made more excellent.

The specific value of the average length of the second carbon fiber 12 (the same applies to the prepreg 200 described later and the average length of the second carbon fiber 12 contained in the molded product) is not particularly limited, but is 1.0 mm. It is preferably 10 mm or more, more preferably 1.5 mm or more and 9.0 mm or less, and further preferably 2.0 mm or more and 8.0 mm or less.

As a result, the above-mentioned effects can be exhibited more remarkably, and the strength of the carbon fiber sheet material 100, the molded product, and the like can be made more excellent. Further, even when the molded product is subjected to a thermal history, internal stress is unlikely to accumulate, dimensional accuracy can be improved, and unintentional deformation or the like during use of the molded product is unlikely to occur.

The average width of the second carbon fiber 12 (the same applies to the prepreg 200 described later and the average width of the second carbon fiber 12 contained in the molded product) is preferably 1.0 μm or more and 20 μm or less, preferably 2.0 μm. It is more preferably 18 μm or less, and further preferably 3.0 μm or more and 15 μm or less.

As a result, the strength of the carbon fiber sheet material 100 and the molded body can be made sufficiently excellent, and the processability and moldability of the carbon fiber sheet material 100 and the like can be made particularly excellent. In addition, it is possible to more effectively prevent undesired irregularities from being generated on the surface of the carbon fiber sheet material 100, the molded product, or the like.

The second carbon fiber 12 may be recycled, but is preferably recycled from carbon fiber reinforced plastics (CFRP).

High-quality carbon fibers are generally used for CFRP, and by using the second carbon fiber 12 recycled from CFRP, the quality of the carbon fiber sheet material 100, the molded body, etc. should be further improved. Can be done. Further, by using CFRP as a recycled raw material, it is possible to more preferably control the formation of the bundle 10 described later and the adjustment of the composition of the deposit 2 and the amount of the deposit.

The second carbon fiber 12 may be recycled by any method, but can be preferably obtained by, for example, heat-treating the crushed and crushed recycled raw material.

The heat treatment conditions for the recycled raw material are not particularly limited, but for example, a first heat treatment at a temperature of 300 ° C. or higher and 400 ° C. or lower in an air atmosphere (heat treatment mainly for the purpose of thermal decomposition of the resin material) and air. A second heat treatment (mainly a heat treatment for the purpose of removing carbonized residue) at a temperature of 400 ° C. or higher and 600 ° C. or lower in an atmosphere satisfies the above conditions. Carbon fiber 12 can be preferably obtained.

As the second carbon fiber 12, a plurality of types of carbon fibers recycled under different conditions may be used.

In the present embodiment, the organic component derived from the recycled raw material (for example, CFRP, etc.) of the second carbon fiber 12 and / or the carbide of the organic component adhere to the surface of the second carbon fiber 12 as the deposit 2. It was done.

Such deposits 2 are generally superior in adhesion to carbon fibers as compared with deposits adhered to virgin carbon fibers as a post-treatment. Further, such an deposit 2 has an excellent affinity with the binder 20 and the resin material (impregnated resin) 30 and the like. Therefore, it is advantageous for further improving the strength and reliability of the carbon fiber sheet material 100, the molded product, and the like. Further, since the deposit 2 is attached to the surface of the second carbon fiber 12, the bundled body 10 described later can be formed more preferably, and the strength and stability of the bundled body 10 are more excellent. Can be considered.
Examples of the organic component include a sizing agent and a matrix resin.

The coverage of the deposit 2 on the surface of the second carbon fiber 12 (the same applies to the prepreg 200 described later, the coverage of the deposit 2 on the surface of the second carbon fiber 12 contained in the molded product) is particularly high. Although not limited, it is preferably 2% or more and 40% or less, more preferably 4% or more and 30% or less, and further preferably 6% or more and 20% or less.

Thereby, the strength and reliability of the carbon fiber sheet material 100 and the molded product can be further improved.

Further, in the present embodiment, a bundle-shaped body 10 in which a plurality of second carbon fibers 12 are bonded to form a bundle is included.

Thereby, the strength and reliability of the carbon fiber sheet material 100 and the molded product can be further improved.

In particular, in the present embodiment, the deposit 2 includes a bundle 10 in which a plurality of second carbon fibers 12 are bonded to form a bundle.

Thereby, the strength and stability of the bundled body 10 itself can be improved, and the strength and reliability of the carbon fiber sheet material 100 and the molded body can be further improved.

The aspect ratio (the same applies to the prepreg 200 described later and the bundled body 10 contained in the molded body), which is the ratio (L / W) of the length L to the width W of the bundled body 10, is 2 or more and 500 or less. It is more preferable that it is 10 or more and 450 or less, and further preferably 20 or more and 400 or less.

By satisfying such conditions, the strength and reliability of the carbon fiber sheet material 100 and the molded product are further improved while improving the moldability (processability such as bending) at the time of manufacturing the molded product. Can be made to.

When the carbon fiber sheet material 100 (the same applies to the prepreg 200 and the molded body described later) contains a plurality of bundled bodies 10, the average value of the aspect ratios of the plurality of bundled bodies 10 is the above. It is preferable to satisfy the above conditions.

The average value of the aspect ratio is, for example, the average of 100 bundles 10 included in the field of view of microscopic observation selected at random, and the aspect ratios for these are obtained. The value can be adopted. When 100 bundles are not included in one field of view, a total of 100 bundles 10 are randomly selected in a plurality of different fields of view, and the average value of the aspect ratios for these is adopted. can do.

Further, in the illustrated configuration, the carbon fiber sheet material 100 (the same applies to the prepreg 200 and the molded body described later) comprises the bundled body 10 in addition to the second carbon fiber 12 constituting the bundled body 10. It also contains a second carbon fiber 12 that does not.

As a result, both excellent strength and ease of handling (including moldability) can be achieved at a higher level.

When the content of the first carbon fiber 11 in the carbon fiber sheet material 100 is X _VCF [mass%] and the content of the second carbon fiber 12 is X _RCF [mass%], 0.006 ≤ X _VCF. It is preferable to satisfy the relationship of / X _{RCF ≤ 1.0, more preferably the relationship of 0.015 ≤ X VCF} / X _RCF ≤ 0.60, and 0.020 ≤ X _VCF / X _RCF ≤ 0. It is more preferable to satisfy the relationship of .33.

By satisfying such a condition, the effect (synergistic effect) due to the coexistence of the first carbon fiber 11 and the second carbon fiber 12 is exhibited more remarkably.

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

By satisfying such a condition, the effect (synergistic effect) due to the coexistence of the first carbon fiber 11 and the second carbon fiber 12 is exhibited more remarkably.

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

By satisfying such conditions, the original characteristics of the carbon fiber 1 are exhibited more effectively, and the strength, reliability, etc. of the carbon fiber sheet material 100 and the molded product are made more excellent. Can be done.

(binder)
The binder 20 has a function of binding carbon fibers 1 (first carbon fiber 11 and second carbon fiber 12). Further, when the binder 20 remains in the molded product manufactured by using the carbon fiber sheet material 100, it may form a part of the matrix resin in the molded product.

The binder 20 may directly bond the carbon fibers 1, or may bond the carbon fibers 1 to each other via other components (for example, deposits 2 or other components described later). It may be.

Examples of the binder 20 include polyesters such as polyethylene terephthalate, polybutylene terephthalate and polylactic acid; polyolefins such as polyethylene and polypropylene; polyamides such as nylon 6, nylon 6 and 6; polyvinyl alcohol (PVA), polyvinyl acetate and polyphenylene sulfide. , Thermoplastic resins such as polyether ketones, polycarbonates and phenoxy resins, thermosetting resins such as epoxy resins, phenol resins, melamine resins and unsaturated polyesters, copolymers thereof, modified resins, polymer alloys and the like. And one or a combination of two or more selected from these can be used.

Above all, the binder 20 is preferably polyvinyl alcohol.
As a result, the binder 20 can more preferably bond and immobilize the carbon fibers 1 to each other, and can impart suitable drapeability to the carbon fiber sheet material 100.

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

By satisfying such conditions, the original characteristics of the carbon fiber 1 are exhibited more effectively, and the strength, reliability, etc. of the carbon fiber sheet material 100 and the molded product are made more excellent. Can be done.

(Other ingredients)
The carbon fiber sheet material 100 may contain components (other components) other than those described above.

Such components include, for example, plasticizers, colorants, antioxidants, ultraviolet absorbers, light stabilizers, softeners, modifiers, rust inhibitors, fillers, surface lubricants, corrosion inhibitors, heat resistant agents. Stabilizers, lubricants, primers, antistatic agents, polymerization inhibitors, cross-linking agents, catalysts, leveling agents, thickeners, dispersants, anti-aging agents, flame retardants, antioxidants, corrosion inhibitors, carbon nanotubes, carbon Examples thereof include nanofibers, cellulose nanofibers, fullerene, and graphite.

The thickness of the carbon fiber sheet material 100 is not particularly limited, but 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 0.25 mm or more and 1. It is more preferably 5 mm or less.

As a result, the ease of handling the carbon fiber sheet material 100, the ease of manufacturing the prepreg 200 and the like, the moldability of the molded product, and the like can be further improved.

The use of the carbon fiber sheet material 100 is not particularly limited, and for example, it can be used for manufacturing a prepreg or a molded product, which will be described later, or as a heat radiating sheet / fin, a conductive sheet, an electromagnetic wave shielding material, an electrode material, or the like. ..

[Prepreg]
Next, the prepreg of the present invention will be described.

The prepreg of the present invention is a sheet-shaped member that can be used for producing a molded product having a predetermined shape by heat-press molding, and is a first carbon fiber which is a virgin carbon fiber and a recycled carbon fiber. It contains a second carbon fiber, and also contains a resin material. The resin material may be either a thermoplastic resin or a thermosetting resin. In the present invention, the prepreg is a concept including a semi-preg incompletely impregnated with a resin material.

<First Embodiment>
FIG. 3 is a plan view schematically showing a first embodiment of the prepreg of the present invention.

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

This makes it possible to provide a prepreg 200 that can be used for producing a molded product having excellent strength and reliability with excellent moldability.

Further, since excellent moldability can be obtained during the production of the molded product, the manufacturing conditions (for example, temperature, pressure, etc.) of the molded product can be relaxed. Therefore, it is possible to use a manufacturing apparatus having a simple structure, suppress the load on the manufacturing apparatus, and extend the life of the manufacturing apparatus. It is also advantageous from the viewpoint of suppressing the production cost of the molded product.

Further, even if the carbon fiber content is increased, the excellent moldability can be maintained, so that the resin material content can be lowered, and the excellent properties of the carbon fiber in the molded product can be reduced. (For example, strength, thermal conductivity, conductivity, etc.) can be exhibited more effectively.

It is also preferable to use the recycled second carbon fiber 12 from the viewpoint of resource saving and reduction of environmental load.

The resin material (impregnated resin) 30 constitutes a matrix resin in the molded product.

Examples of the resin material (impregnated resin) 30 include polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polylactic acid; polyolefins such as polyethylene and polypropylene; polyamides such as nylon 6, nylon 6, 6; polyvinyl alcohol (PVA), and poly. Thermoplastic resins such as vinyl acetate, polyphenylene sulfide, polyether ketone, polycarbonate, phenoxy resin, thermosetting resins such as epoxy resin, phenol resin, melamine resin, unsaturated polyester, copolymers thereof, modified resins, etc. Examples thereof include polymer alloys, and one or a combination of two or more selected from these can be used.

Above all, the resin material (impregnated resin) 30 is preferably a thermosetting resin.
As a result, the strength, durability, etc. of the molded product can be made particularly excellent.

The content of the resin material (impregnated resin) 30 in the prepreg 200 is preferably 3.0% by mass or more and 70% by mass or less, and more preferably 4.0% by mass or more and 68% by mass or less. It is more preferably 0.0% by mass or more and 65% by mass or less.

By satisfying such conditions, the strength and reliability of the molded product manufactured by using the prepreg 200 are sufficiently excellent, and the moldability when manufacturing the molded product is further improved. be able to.

The content of carbon fiber 1 in the prepreg 200 (the sum of the content of the first carbon fiber 11 and the content of the second carbon fiber 12) is preferably 16% by mass or more and 96% by mass or less. It is more preferably 17.5% by mass or more and 95% by mass or less, and further preferably 23% by mass or more and 93% by mass or less.

By satisfying such conditions, the original characteristics of the carbon fiber 1 are exhibited more effectively, and the strength and reliability of the molded product produced by using the prepreg 200 are sufficiently excellent. On the other hand, the moldability at the time of manufacturing the molded product can be made more excellent.

Further, the content of carbon fiber 1 in the prepreg 200 (the sum of the content of the first carbon fiber 11 and the content of the second carbon fiber 12) is X _CF [mass%], and the resin material in the prepreg 200. When the content of (impregnated resin) 30 is X _IR [mass%], it is preferable to satisfy the relationship of _{0.035 ≤ X IR} / X _{CF ≤ 4.3, and 0.045 ≤ X IR} / X _CF. It is more preferable to satisfy the relationship of ≦ 3.8, and further preferably to satisfy the relationship of 0.055 ≦ X _IR / X _CF ≦ 2.8.

By satisfying such conditions, the original characteristics of the carbon fiber 1 are exhibited more effectively, and the strength and reliability of the molded product produced by using the prepreg 200 are sufficiently excellent. On the other hand, the moldability at the time of manufacturing the molded product can be made more excellent.

The prepreg 200 may contain components (other components) other than those described above.
Such components include, for example, plasticizers, colorants, antioxidants, ultraviolet absorbers, light stabilizers, softeners, modifiers, rust inhibitors, fillers, surface lubricants, corrosion inhibitors, heat resistant agents. Stabilizers, lubricants, primers, antistatic agents, polymerization inhibitors, cross-linking agents, catalysts, leveling agents, thickeners, dispersants, anti-aging agents, flame retardants, antioxidants, corrosion inhibitors, carbon nanotubes, carbon Examples thereof include nanofibers, cellulose nanofibers, fullerene, and graphite.

The thickness of the prepreg 200 is not particularly limited, but 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 0.25 mm or more and 1.5 mm or less. It is even more preferable to have it.

As a result, the prepreg 200 can be made more excellent in ease of handling, ease of manufacture, moldability when formed into a molded product, and the like.

<Second Embodiment>
FIG. 4 is a plan view schematically showing a second embodiment of the prepreg of the present invention. In the following description, the differences from the above-described embodiment will be mainly described, and the description of the same matters will be omitted.

The prepreg 200 of the present embodiment includes a plurality of carbon fibers 1, a plurality of resin fibers 40, and a binder 20 for binding the carbon fibers 1 and the resin fibers 40. The carbon fiber 1 includes a first carbon fiber 11 which is a virgin carbon fiber and a second carbon fiber 12 which is a recycled carbon fiber.

This makes it possible to provide a prepreg 200 that can be used for producing a molded product having excellent strength and reliability with excellent moldability.

Further, since excellent moldability can be obtained during the production of the molded product, the manufacturing conditions (for example, temperature, pressure, etc.) of the molded product can be relaxed. Therefore, it is possible to use a manufacturing apparatus having a simple structure, suppress the load on the manufacturing apparatus, and extend the life of the manufacturing apparatus. It is also advantageous from the viewpoint of suppressing the production cost of the molded product.

Further, even if the carbon fiber content is increased, the excellent moldability can be maintained, so that the resin material content can be lowered, and the excellent properties of the carbon fiber in the molded product can be reduced. (For example, strength, thermal conductivity, conductivity, etc.) can be exhibited more effectively.

It is also preferable to use the recycled second carbon fiber 12 from the viewpoint of resource saving and reduction of environmental load.
The resin fiber 40 constitutes a matrix resin in a molded product.

Further, in the prepreg 200 of the present embodiment, regarding the carbon fiber 1 (first carbon fiber 11, the second carbon fiber 12), the deposit 2, and the binder 20, the conditions other than the conditions described below are carbon. It is preferable to satisfy the same conditions as described in the fiber sheet material 100.

Examples of the constituent material of the resin fiber 40 include polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polylactic acid; polyolefins such as polyethylene and polypropylene; polyamides such as nylon 6, nylon 6, 6; and polyether such as polyetheretherketone. Ketone; thermoplastic resins such as polyvinyl acetate, polyphenylene sulfide, polycarbonate, polystyrene, acrylonitrile-butadiene-styrene resin (ABS resin), polyvinyl chloride resin, phenoxy resin, epoxy resin, phenol resin, melamine resin, unsaturated Examples thereof include thermosetting resins such as polyester, copolymers thereof, modified resins, polymer alloys, and the like, and one or a combination of two or more selected from these can be used.

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

As a result, the prepreg 200 can be handled more easily, and the moldability at the time of manufacturing the molded product and the characteristics (strength, reliability, etc.) of the molded product can be compatible at a higher level.

The average length of the resin fiber 40 is not particularly limited, but is preferably 2.0 mm or more and 20 mm or less, more preferably 3.0 mm or more and 18 mm or less, and further preferably 4.0 mm or more and 16 mm or less. preferable.

Thereby, the ease of handling of the prepreg 200, the strength and reliability of the molded product manufactured by using the prepreg 200, the moldability at the time of manufacturing the molded product, and the like can be further improved.

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 relationship of _{0.10 ≤ L RF} / L _{CF ≤ 18.} , 0.25 ≤ L _RF / L _CF ≤ 11 is more preferable, and 0.45 ≤ L _RF / L _CF ≤ 7.0 is more preferable.

Thereby, the ease of handling of the prepreg 200, the strength and reliability of the molded product manufactured by using the prepreg 200, the moldability at the time of manufacturing the molded product, and the like can be further improved.

The content of carbon fiber 1 in the prepreg 200 (the sum of the content of the first carbon fiber 11 and the content of the second carbon fiber 12) is preferably 16% by mass or more and 96% by mass or less. It is more preferably 17.5% by mass or more and 95% by mass or less, and further preferably 23% by mass or more and 93% by mass or less.

By satisfying such conditions, the original characteristics of the carbon fiber 1 are exhibited more effectively, and the strength and reliability of the molded product produced by using the prepreg 200 are sufficiently excellent. On the other hand, the moldability at the time of manufacturing the molded product can be made more excellent.

When the content of the first carbon fiber 11 in the prepreg 200 is X _VCF [mass%] and the content of the second carbon fiber 12 is X _RCF [mass%], 0.006 ≤ X _VCF / X _RCF. Satisfying the relationship of ≤1.0, more preferably satisfying the relationship of _{0.015≤X VCF} / X _{RCF ≤0.60 , 0.020≤X VCF} / X _RCF ≤0.33 It is even more preferable to satisfy the relationship.

By satisfying such conditions, the original characteristics of the carbon fiber 1 are exhibited more effectively, and the strength and reliability of the molded product produced by using the prepreg 200 are sufficiently excellent. On the other hand, the moldability at the time of manufacturing the molded product can be made more excellent.

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

Thereby, the ease of handling of the prepreg 200, the strength and reliability of the molded product manufactured by using the prepreg 200, the moldability at the time of manufacturing the molded product, and the like can be further improved.

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

Thereby, the ease of handling of the prepreg 200, the strength and reliability of the molded product manufactured by using the prepreg 200, the moldability at the time of manufacturing the molded product, and the like can be further improved.

The content of carbon fiber 1 in the prepreg 200 (the sum of the content of the first carbon fiber 11 and the content of the second carbon fiber 12) is X _CF [mass%], and the content of the resin fiber 40 is X. _{When RF} [mass%] is set, it is preferable to satisfy the relationship of _{0.30 ≤ X CF} / X _RF ≤ 28, and more preferably the relationship of _{0.40 ≤ X CF} / X _{RF ≤ 20 is satisfied.} It is more preferable to satisfy the relationship of 0.50 ≦ X _CF / X _{RF ≦ 15.}

By satisfying such conditions, the original characteristics of the carbon fiber 1 are exhibited more effectively, and the strength and reliability of the molded product produced by using the prepreg 200 are sufficiently excellent. On the other hand, the moldability at the time of manufacturing the molded product can be made more excellent.

The prepreg 200 may contain components (other components) other than those described above.
Such components include, for example, plasticizers, colorants, antioxidants, ultraviolet absorbers, light stabilizers, softeners, modifiers, rust inhibitors, fillers, surface lubricants, corrosion inhibitors, heat resistant agents. Stabilizers, lubricants, primers, antistatic agents, polymerization inhibitors, cross-linking agents, catalysts, leveling agents, thickeners, dispersants, anti-aging agents, flame retardants, antioxidants, corrosion inhibitors, carbon nanotubes, carbon Examples thereof include nanofibers, cellulose nanofibers, fullerene, and graphite.

Further, the gaps between the fibers may be impregnated with the resin material (impregnated resin) described in the first embodiment.

[Molded product]
Next, the molded product of the present invention will be described.

The molded product of the present invention is formed by heat-press molding the prepreg of the present invention.
Thereby, it is possible to provide a molded product having excellent strength and reliability.

The molded product of the present invention may have a portion formed by heat-press molding the prepreg of the present invention, and may further have, for example, a coating film or the like.

The molded body of the present invention may be used for any purpose, and the molded body of the present invention is used, for example, as a component of a vehicle (for example, an automobile, a bicycle, a train, an aircraft, a rocket, an elevator, etc.). , Electronic and electrical component components (for example, personal computers, mobile phones (including smartphones, PHS, etc.), housings for portable terminals such as tablets), construction, civil engineering structure members, furniture, etc. Can be mentioned.

[Manufacturing method of carbon fiber sheet material]
Next, the method for producing the carbon fiber sheet material of the present invention will be described.

The carbon fiber sheet material 100 described above includes, for example, a first carbon fiber 11 which is a virgin carbon fiber, a second carbon fiber 12 which is a recycled carbon fiber, and a first carbon fiber 11 and a second carbon fiber. It can be produced by using a method having a step (paper making step) of mixing the binder 20 to which the carbon fibers 12 are bonded.

Thereby, a manufacturing method capable of stably manufacturing the carbon fiber sheet material 100 which is excellent in strength and reliability and can be used for manufacturing a molded product having excellent strength and reliability with excellent moldability. Can be provided.

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

As a result, the adhesion to the resin material such as the binder 20 can be improved, and the strength and reliability of the carbon fiber sheet material 100 and the molded product can be made more excellent.

Examples of the sizing agent include epoxy resin, phenol resin, polyethylene glycol, polyurethane, polyester, emulsifier, surfactant and the like.

The content of carbon fiber 1 (the sum of the content of the first carbon fiber 11 and the content of the second carbon fiber 12) in the papermaking composition is not particularly limited, but is 0.01% by mass or more and 0. By setting the content to 0.3% by mass or less, the bundled body 10 as described above can be efficiently formed.

[Manufacturing method of prepreg]
Next, the method for producing the prepreg of the present invention will be described.

<First Embodiment>
The prepreg 200 according to the first embodiment described above uses, for example, a method having a step (impregnation step) of impregnating the carbon fiber sheet material 100 obtained through the papermaking step described above with the resin material (impregnated resin) 30. Can be manufactured stably.

In the impregnation step, for example, a sheet material composed of a thermosetting resin or a thermoplastic resin in an uncured state (B stage) as the resin material (impregnated resin) 30 is thermally transferred to the carbon fiber sheet material 100. Examples thereof include a method and a method of impregnating the carbon fiber sheet material 100 with the liquid resin material (impregnated resin) 30.

<Second Embodiment>
The prepreg 200 according to the second embodiment described above includes, for example, a first carbon fiber 11 which is a virgin carbon fiber, a second carbon fiber 12 which is a recycled carbon fiber, a resin fiber 40, and a first carbon fiber. It can be stably produced by using a method having a step (paper making step) of mixing the carbon fiber 11, the second carbon fiber 12, and the binder 20 that binds the resin fiber 40.

Further, in the manufacturing method of the first embodiment described above, the carbon fiber sheet material 100 obtained through the paper making step is impregnated, whereas in the manufacturing method of the present embodiment, the carbon fiber 1 (the first) is carried out in the paper making step. It is not necessary to use the carbon fiber 11 of 1 and the second carbon fiber 12), the resin fiber 40, and the binder 20 and perform the subsequent impregnation step. Therefore, the productivity of the prepreg 200 can be increased.

[Manufacturing method of molded product]
Next, a method for producing the molded product of the present invention will be described.

The above-mentioned molded product can be stably produced, for example, by using a method having a step (molding step) of heat-press molding the prepreg 200 produced as described above.

When manufacturing the molded product, a plurality of prepregs 200 may be laminated.
The number of laminated sheets is not particularly limited, but is preferably 2 or more and 50 or less, and more preferably 3 or more and 30 or less.

When a plurality of prepregs 200 are used, these prepregs 200 may have different conditions or the same conditions.
Further, an intermediate layer may be provided between the adjacent prepregs 200.

Further, prior to the joining step, a process of joining a plurality of prepregs 200 may be performed. Examples of the method for joining a plurality of prepregs 200 include welding (including solvent welding, polymerization welding, etc.), fusion, adhesion, and the like.

The heating temperature in the molding process varies depending on the type and content of the resin material (impregnated resin) 30 and the resin fiber 40, and is not particularly limited, but is preferably 100 ° C. or higher and 380 ° C. or lower, and 110 ° C. or higher and 350 ° C. or lower. It is more preferable that the temperature is 120 ° C. or higher and 300 ° C. or lower.

The molding pressure in the molding step varies depending on the type and content of the resin material (impregnated resin) 30 and the resin fiber 40, and is not particularly limited, but is preferably 0.1 MPa or more and 15 MPa or less, preferably 0.2 MPa or more. It is more preferably 12 MPa or less, and further preferably 0.3 MPa or more and 10 MPa or less.

When the prepreg 200 contains a thermosetting resin, the curing reaction of the thermosetting resin proceeds by heating in the molding step, and the obtained molded product has excellent heat resistance and the like.

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

For example, the carbon fiber sheet material manufacturing method, the prepreg manufacturing method, and the molded product manufacturing method further include other steps (pretreatment step, intermediate treatment step, posttreatment step, etc.) in addition to the above-mentioned steps. You may be.

Further, the carbon fiber sheet material, the prepreg, and the molded product of the present invention are not limited to those produced by the above-mentioned method, and may be produced by any method.

Further, in the above-described embodiment, in the carbon fiber sheet material, the prepreg, and the molded body, a configuration in which the carbon fibers constituting the bundled body and the carbon fibers not forming the bundled body are included is typically described. A configuration may include only one of these.

Hereinafter, the present invention will be described in detail based on Examples and Comparative Examples, but the present invention is not limited thereto. The treatment and measurement, which did not particularly indicate the temperature conditions, were carried out at 20 ° C.

<< 1 >> Production of Carbon Fiber Sheet Material The carbon fiber sheet material of each Example and each Comparative Example was produced as follows.

(Example A1)
First, virgin carbon fibers (first carbon fiber, fiber average diameter (average width) 7.0 μm, average length 6.0 mm): 20 parts by mass and recycled carbon fibers (second carbon fiber, fiber). Average diameter (average width) 7.0 μm, average length 5.0 mm): 75 parts by mass and polyvinyl alcohol fiber as a binder (fineness 1.1 decitex, average length 3.0 mm, weighted average density: 1.20 g / Cm ³ ): A composition consisting of 5.0 parts by mass was mixed and dispersed in water to prepare a papermaking slurry having a solid content of 0.03% by mass.

Next, an anionic polyacrylamide as a dispersant: 0.001 part by mass was added to 100 parts by mass of the papermaking slurry to obtain a dispersion liquid, and this dispersion liquid was applied to a mesh having a mesh gap of 0.2 mm. It was sucked onto the papermaking surface of the conveyor and deposited to form a sheet (papermaking process).

Then, the humidified sheet produced in the papermaking process was heated and dried at 120 ° C. to melt the polyvinyl alcohol fibers and bond the carbon fibers at the intersections to obtain a carbon fiber sheet material.

As the recycled carbon fiber, the crushed and crushed CFRP is subjected to a first heat treatment at 350 ° C. in an air atmosphere, and further subjected to a second heat treatment at 550 ° C. in an air atmosphere. The obtained one was used.

(Examples A2 and A3)
A carbon fiber sheet material 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 as shown in Table 1.

(Comparative Example A1)
A carbon fiber sheet material 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 compounding ratio of each component was as shown in Table 1.

(Comparative Example A2)
A carbon fiber sheet material 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 compounding ratio of each component was as shown in Table 1.

Table 1 summarizes the configurations of the carbon fiber sheet materials of each of the above-mentioned Examples and Comparative Examples. The second carbon fibers used in each of the above Examples and Comparative Example A2 had deposits derived from recycled raw materials attached to a part of the surface thereof. Further, the carbon fiber sheet materials of the respective Examples and Comparative Example A2 contained not only a bundle containing a plurality of carbon fibers but also carbon fibers not forming the bundle. Moreover, the thickness of the carbon fiber sheet material of each of the Examples and Comparative Examples was 0.5 mm or more and 0.8 mm or less.

<< 2 >> Production of prepregs The prepregs of each Example and each Comparative Example were produced as follows.

(Example B1)
First, a methanol solution (40% by mass) of a phenol resin as an uncured thermosetting resin was prepared.

Next, the methanol solution was applied to the carbon fiber sheet material of Example A1 and impregnated. Then, the mixture was heated to 80 ° C. to remove methanol, and further heat-treated at 150 ° C. for 15 minutes to cure the phenol resin to obtain a prepreg.

(Examples B2 and B3)
A prepreg was produced in the same manner as in Example B1 except that the carbon fiber sheet material produced in Examples A2 and A3 was used instead of the one produced in Example A1.

(Example B4)
First, virgin carbon fiber (first carbon fiber, fiber average diameter (average width) 7.0 μm, average length 6.0 mm): 5.0 parts by mass and recycled carbon fiber (second carbon fiber). , Fiber average diameter (average width) 7.0 μm, average length 5.0 mm): 35.2 parts by mass and polyvinyl alcohol fiber as a binder (fineness 1.1 decitex, average length 3.0 mm, weighted average density : 1.20 g / cm ³ ): A composition consisting of 2.9 parts by mass and 6 nylon fibers as resin fibers (fineness 1.1 decitex, average length 6.0 mm): 56.9 parts by mass. It was mixed and dispersed in water to prepare a papermaking slurry having a solid content of 0.03% by mass.

Next, an anionic polyacrylamide as a dispersant: 0.001 part by mass was added to 100 parts by mass of the papermaking slurry to obtain a dispersion liquid, and this dispersion liquid was used as a mesh having a mesh gap of 0.3 mm. It was sucked onto the papermaking surface of the conveyor and deposited to form a sheet (papermaking process).

Then, the humidified sheet produced in the papermaking process was heated and dried at 120 ° C. to melt the polyvinyl alcohol fibers and bond the carbon fibers at the intersections to obtain a prepreg. In the obtained prepreg, the nylon 6 fibers did not melt and maintained the state of the fibers.

As the recycled carbon fiber, the crushed and crushed CFRP is subjected to a first heat treatment at 350 ° C. in an air atmosphere, and further subjected to a second heat treatment at 550 ° C. in an air atmosphere. The obtained one was used.

(Examples B5 and 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 as shown in Table 2.

(Comparative Examples B1 and B2)
A prepreg was produced in the same manner as in Example B1 except that the carbon fiber sheet material produced in Comparative Examples A1 and A2 was used instead of the carbon fiber sheet material produced in Example A1.

(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 compounding 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 compounding ratio of each component was as shown in Table 2.

Table 2 summarizes the configurations of the prepregs of each of the above-mentioned Examples and Comparative Examples. The second carbon fibers used in each of the above Examples and Comparative Examples B2 and B4 had deposits derived from recycled raw materials attached to a part of the surface thereof. Further, the prepregs of the respective Examples and Comparative Examples B2 and B4 contained not only a bundle containing a plurality of carbon fibers but also carbon fibers not forming the bundle. The thickness of the prepregs of each of the Examples and Comparative Examples was 0.8 mm or more and 1.4 mm or less.

<< 3 >> Manufacture of molded article The molded article of each Example and each Comparative Example was produced as follows.

(Example C1)
First, 15 prepregs produced in Example B1 were laminated.

Next, the laminated body of the prepreg was heat-pressurized under the conditions of ^{50 kg / cm 2 and 150 ° C.} As a result, the thermosetting resin contained in the prepreg was cured, and a flat plate-shaped molded product A in which a plurality of prepregs were bonded to each other between layers was obtained.

Further, the molded body B was manufactured in the same manner as the molded body A except that the outer peripheral surface was molded into a bent plate having an L-shaped radius of curvature.

(Examples C2 and C3)
Molds (molds A and B) were produced in the same manner as in Example C1 except that the prepregs produced in Examples B2 and B3 were used instead of those produced in Example B1. ..

(Example C4)
First, 15 prepregs produced in Example B4 were laminated.

Next, the laminated body of the prepreg was heat-pressurized under the conditions of ^{50 kg / cm 2 and 250 ° C.} As a result, the thermoplastic resin contained in the prepreg was softened and melted, and a flat plate-shaped molded product A in which a plurality of prepregs were bonded to each other between layers was obtained.

Further, the molded body B was manufactured in the same manner as the molded body A except that the outer peripheral surface was molded into a bent plate having an L-shaped radius of curvature.

(Examples C5 and C6)
Molds (molds A and B) were produced in the same manner as in Example C4, except that the prepregs produced in Examples B5 and B6 were used instead of those produced in Example B4. ..

(Comparative Examples C1 and C2)
Molds (molds A and B) were produced in the same manner as in Example C1 except that the prepregs produced in Comparative Examples B1 and B2 were used instead of those produced in Example B1. ..

(Comparative Examples C3, C4)
Molds (molds A and B) were produced in the same manner as in Example C4, except that the prepregs produced in Comparative Examples B3 and B4 were used instead of those produced in Example B5. ..

The molded bodies of the respective Examples and Comparative Examples C2 and C4 contained not only a bundle containing a plurality of carbon fibers but also carbon fibers not forming the bundle.

<< 4 >> Evaluation << 4-1 >> Bending strength evaluation For the molded product A of Examples C1 to C6 and Comparative Examples C1 to C4, the bending strength obtained by a bending test according to JIS K7074 was measured, and the bending strength was measured according to the following criteria. I evaluated it accordingly.

A: Bending strength is 250 MPa or more.
B: Bending strength is 200 MPa or more and less than 250 MPa.
C: Bending strength is 150 MPa or more and less than 200 MPa.
D: Bending strength is 100 MPa or more and less than 150 MPa.
E: Bending strength is less than 100 MPa.

<< 4-2 >> Appearance evaluation (visual evaluation)
The molded products B of Examples C1 to C6 and Comparative Examples C1 to C4 were visually observed and evaluated according to the following criteria.

A: No poor appearance is observed.
B: Almost no poor appearance is observed.
C: A slight appearance defect is observed.
D: Poor appearance is clearly recognized.
E: Poor appearance is noticeable.

(Evaluation by microscope)
The vicinity of the bent portion of the molded product B of Examples C1 to C6 and Comparative Examples C1 to C4 was observed with a microscope and evaluated according to the following criteria.

A: There is no variation in the amount of exposed carbon fibers.
B: A region where a large amount of carbon fiber is exposed and a region where the amount of exposed carbon fiber is small and a large amount of resin material is exposed coexist, and a slight variation in the amount of exposed carbon fiber is observed.
C: A region where a large amount of carbon fiber is exposed and a region where the amount of exposed carbon fiber is small and a large amount of resin material is exposed coexist, and a variation in the amount of exposed carbon fiber is clearly observed.
D: A region where a large amount of carbon fiber is exposed and a region where the amount of exposed carbon fiber is small and a large amount of resin material is exposed coexist, and a variation in the amount of exposed carbon fiber is remarkably observed.
These results are summarized in Table 3.

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

The carbon fiber sheet material of the present invention contains a plurality of carbon fibers and a binder for binding the carbon fibers, and the carbon fibers include a first carbon fiber which is a virgin carbon fiber and a recycled carbon fiber. It contains a second carbon fiber which is. Therefore, it is possible to provide a carbon fiber sheet material which is excellent in its own strength and reliability and can be used for producing a molded product having excellent strength and reliability with excellent moldability. Therefore, the carbon fiber sheet material of the present invention has industrial applicability.

100 ... Carbon fiber sheet material 200 ... Prepreg 1 ... Carbon fiber 11 ... First carbon fiber 12 ... Second carbon fiber 2 ... Adhesion 10 ... Bundle 20 ... Binder 30 ... Resin material (impregnated resin)
40 ... Resin fiber

Claims (27)

A carbon fiber sheet material containing a plurality of carbon fibers and a binder for binding the carbon fibers.
A carbon fiber sheet material containing, as the carbon fiber, a first carbon fiber which is a virgin carbon fiber and a second carbon fiber which is a recycled carbon fiber. The carbon fiber sheet material according to claim 1, wherein the average length of the second carbon fiber is shorter than the average length of the first carbon fiber. When the average length of the first carbon fiber is _LVCF [mm] and the average length of the second carbon fiber is _LRCF [mm], the relationship of _{1.1 ≤ LVCF} / L _{RCF ≤ 30.} The carbon fiber sheet material according to claim 2, which satisfies the above requirements. The carbon fiber sheet material according to any one of claims 1 to 3, wherein the average length of the second carbon fiber is 1.0 mm or more and 10 mm or less. When 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 carbon fiber sheet material according to any one of claims 1 to 4, which satisfies the above relationship. Any of claims 1 to 5, wherein the second carbon fiber has an organic component derived from a recycled raw material of the second carbon fiber and / or a carbide of the organic component adhered to the surface thereof as an deposit. The carbon fiber sheet material according to item 1. The carbon fiber sheet material according to claim 6, wherein the coverage of the deposit on the surface of the second carbon fiber is 2% or more and 40% or less. The carbon fiber sheet material according to claim 6 or 7, which comprises a bundle-like body in which a plurality of the second carbon fibers are bonded by the deposit to form a bundle. The carbon fiber sheet material according to claim 8, wherein the aspect ratio, which is the ratio of the length to the width of the bundle, is 2 or more and 500 or less. A prepreg obtained by impregnating the carbon fiber sheet material according to any one of claims 1 to 9 with a resin material. A prepreg containing a plurality of carbon fibers, a plurality of resin fibers, the carbon fibers, and a binder for binding the resin fibers.
The prepreg is characterized by containing, as the carbon fiber, a first carbon fiber which is a virgin carbon fiber and a second carbon fiber which is a recycled carbon fiber. The prepreg according to claim 11, wherein the average length of the resin fibers is 2.0 mm or more and 20 mm or less. Claim 11 that satisfies the relationship of _{0.30 ≤ X CF} / X _RF ≤ 28, where the carbon fiber content is X _CF [mass%] and the resin fiber content is X _RF [mass%]. Or the prepreg according to 12. Claim 11 that satisfies the relationship of _{0.10 ≤ L RF} / L _CF ≤ 18 when the average length of the carbon fibers is L _CF [mm] and the average length of the resin fibers is L _RF [mm]. The prepreg according to any one of 13 to 13. The prepreg according to any one of claims 11 to 14, wherein the average length of the second carbon fiber is shorter than the average length of the first carbon fiber. When the average length of the first carbon fiber is _LVCF [mm] and the average length of the second carbon fiber is _LRCF [mm], the relationship of _{1.1 ≤ LVCF} / L _{RCF ≤ 30.} The prepreg according to claim 15, which satisfies the above. The prepreg according to any one of claims 11 to 16, wherein the average length of the second carbon fiber is 1.0 mm or more and 10 mm or less. When 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 according to any one of claims 11 to 17, which satisfies the relationship of. Any of claims 11 to 18, wherein the second carbon fiber has an organic component derived from a recycled raw material of the second carbon fiber and / or a carbide of the organic component adhered to the surface thereof as an deposit. The prepreg according to item 1. The prepreg according to claim 19, wherein the coverage of the deposit on the surface of the second carbon fiber is 2% or more and 40% or less. The prepreg according to claim 19 or 20, wherein the deposit comprises a bundle of a plurality of the second carbon fibers bonded to each other to form a bundle. The prepreg according to claim 21, wherein the aspect ratio, which is the ratio of the length to the width of the bundle, is 2 or more and 500 or less. A molded product obtained by heat-press molding the prepreg according to any one of claims 10 to 22. A step of mixing a first carbon fiber, which is a virgin carbon fiber, a second carbon fiber, which is a recycled carbon fiber, and a binder that binds the first carbon fiber and the second carbon fiber. A method for producing a carbon fiber sheet material, which comprises having. A method for producing a prepreg, which comprises a step of impregnating a carbon fiber sheet material produced by the method according to claim 24 with a resin material. The first carbon fiber which is a virgin carbon fiber, the second carbon fiber which is a recycled carbon fiber, the resin fiber, the first carbon fiber, the second carbon fiber and the resin fiber are bonded. A method for producing prepreg, which comprises a step of mixing with a binder to be produced. A method for producing a molded product, which comprises a step of heat-press molding a prepreg produced by the method according to claim 25 or 26.

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