Method for supplying granular molding material containing carbon fibers, method for manufacturing resin sheet containing carbon fibers, and device for manufacturing resin sheet containing carbon fibers

Abstract

According to the present invention, a method for continuously supplying a granular molding material containing carbon fibers includes conveying the granular molding material to a discharge end of a first belt conveyor that is provided with a rising incline part and has a conveyor belt whose conveyance surface is an uneven surface. According to the present invention, a method for manufacturing a resin sheet containing carbon fibers includes a first step for continuously supplying a granular molding material containing carbon fibers to a double belt press, and a second step for forming a sheet by fusing particles contained in the granular molding material together by using the double belt press. The first step includes conveying the granular molding material to a discharge end of a first belt conveyor that is provided with a rising incline part and has a conveyor belt whose conveyance surface is an uneven surface.

Description

Method for supplying granular molding material containing carbon fiber, method for manufacturing a resin sheet containing carbon fiber, and device for manufacturing a resin sheet containing carbon fiber

[0001] The present invention relates primarily to a method for supplying a granular molding material containing carbon fibers, a method for producing a resin sheet containing carbon fibers, and an apparatus for producing a resin sheet containing carbon fibers.

[0002] Granular molding materials containing carbon fibers have been proposed as molding materials for use in the production of carbon fiber reinforced polymer (CFRP) products by compression molding (Patent Documents 1 to 3). Patent Documents 1 and 2 further disclose that resin sheets that can be used as molding materials for CFRP products can be produced by fusing the particles that make up such granular molding materials together. Patent Document 3 describes a granular molding material that is composed of a plurality of inorganic fibers, a plurality of organic fibers, and an organic binder.

[0003] International Publication No. 2007 / 020910 International Publication No. 2023 / 167102 Japanese Patent Application Laid-Open No. 2023-144177

[0004] Fig. 1 of Patent Document 2 shows a method for continuously producing a resin sheet by fusing together particles that constitute a granular molding material containing carbon fiber. In order to obtain a resin sheet with a uniform mass per unit length using this method, it is necessary to continuously supply a fixed amount of granular molding material onto a running film.

[0005] The present invention has as its main object the provision of a technique for supplying a granular molding material containing carbon fiber that can be preferably used when continuously producing a resin sheet formed by fusing together particles constituting the granular molding material containing carbon fiber, a method for producing a resin sheet containing carbon fiber using this technique, and an apparatus for producing a resin sheet containing carbon fiber using this technique. The problems to be solved by each embodiment of the present invention may be explicitly or implicitly disclosed in this specification.

[0006] According to one aspect of the present invention, there is provided a method for continuously supplying a granular molding material containing carbon fiber, the method comprising conveying the granular molding material to a discharge end of a first belt conveyor having a conveyor belt with an uneven conveying surface and an upwardly sloping section.

[0007] According to another aspect of the present invention, there is provided a method for producing a resin sheet containing carbon fiber, comprising: a first step of continuously supplying a granular molding material containing carbon fiber to a double belt press; and a second step of using the double belt press to fuse particles contained in the granular molding material to form a sheet, wherein the first step comprises transporting the granular molding material to the discharge end of a first belt conveyor having a conveyor belt with an uneven transport surface and an upwardly sloping section.

[0008] According to yet another aspect of the present invention, there is provided an apparatus for manufacturing a resin sheet containing carbon fiber, the apparatus including: a double belt press for fusing particles contained in a granular molding material containing carbon fiber to form a sheet; and a first belt conveyor having a conveyor belt with an uneven transport surface and an upwardly sloping section for supplying the granular molding material to the double belt press.

[0009] According to one aspect of the present invention, there is provided a technique for supplying granular molding material that can be preferably used when continuously producing a resin sheet made by fusing together particles that constitute a granular molding material containing carbon fiber.

[0010] Fig. 1 is a schematic diagram showing an example of an apparatus for manufacturing a resin sheet containing carbon fiber. Fig. 2 is a schematic diagram showing a part of a cross section obtained when a conveyor belt is cut perpendicular to the width direction. Fig. 3 is a side view showing a part of a spiked lattice, i.e., a schematic diagram showing a part of a spiked lattice as viewed from the width direction. Fig. 4 is a schematic diagram showing a lattice made of rods.

[0011] 1. Granular molding material containing carbon fiber Granular molding material containing carbon fiber is a granule that can be used as a molding material for CFRP products, and in particular, is a granule that can be used as a molding material when producing CFRP products by compression molding.

[0012] Hereinafter, for convenience, the "granular molding material containing carbon fiber" may be simply referred to as the "granular molding material." Furthermore, hereinafter, when simply referring to the "granular molding material," it means the "granular molding material containing carbon fiber" unless otherwise specified.

[0013] 1.1. Examples of Granular Molding Materials Granular molding materials can be broadly divided into thermoplastic and thermosetting types.

[0014] The thermoplastic granular molding material contains at least a thermoplastic polymer as a component other than carbon fiber. The content of the thermoplastic polymer is usually 10% by mass or more, preferably 20% by mass or more, and more preferably 30% by mass or more, based on the total mass of the granular molding material. The content of the thermoplastic polymer is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 65% ​​by mass or less.

[0015] The thermosetting granular molding material contains, as components other than carbon fiber, at least a thermosetting resin and its curing agent. The content of the thermosetting resin is usually 10% by mass or more, preferably 20% by mass or more, and more preferably 30% by mass or more, based on the total mass of the granular molding material. The content of the thermosetting resin is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 65% ​​by mass or less.

[0016] (1) Chopped carbon fiber tow prepreg One example of particles that can constitute the granular molding material is chopped carbon fiber tow prepreg. Chopped carbon fiber tow prepreg is a carbon fiber prepreg obtained by cutting continuous carbon fiber tows impregnated with a resin matrix so that the fiber length is within a range of, for example, 5 mm to 100 mm. The resin matrix may be thermosetting or thermoplastic.

[0017] When the resin matrix of the chopped carbon fiber tow prepreg is thermoplastic, examples of polymers that the resin matrix may contain include polypropylene, polysulfone, polyethersulfone, polyetherketone, polyetheretherketone, aromatic polyamide, aliphatic polyamide, aromatic polyesters such as polybutylene terephthalate and polyethylene terephthalate, aromatic polycarbonate, polyetherimide, polyarylene oxide, polyarylene sulfide, thermoplastic polyimide, polyamideimide, polyethylene, ethylene-vinyl alcohol copolymer, and acrylonitrile butadiene styrene, as well as linear polymers of difunctional epoxy compounds. The resin matrix may contain two or more types of polymers.

[0018] In chopped carbon fiber tow prepregs containing a thermoplastic resin matrix, the fiber volume content is preferably 20 to 50%. However, the fiber volume content is not limited to this range. Among the "chopped strand prepregs" described in the aforementioned Patent Document 1, those containing carbon fibers as reinforcing fibers are a type of chopped carbon fiber tow prepreg referred to in this specification.

[0019] When the resin matrix of the chopped carbon fiber tow prepreg is thermosetting, the resin matrix contains a thermosetting resin and its curing agent. Examples of thermosetting resins include unsaturated polyester resin, vinyl ester resin, cyanate resin, and epoxy resin. In chopped carbon fiber tow prepreg containing a thermosetting resin matrix, the fiber volume content is preferably 50 to 75%, although the fiber volume content is not limited to this range.

[0020] (2) Impregnated Carbon Fiber Agglomerates Another example of particles that can constitute the granular molding material is carbon fiber agglomerates impregnated with a thermosetting resin matrix. In this specification, such carbon fiber agglomerates are referred to as "impregnated carbon fiber agglomerates."

[0021] The impregnated carbon fiber agglomerates can be formed by mixing the flocculent carbon fibers with the liquid composition at a temperature lower than the curing initiation temperature of the liquid composition in a ratio of, for example, 25 to 150 parts by mass of the liquid composition to 100 parts by mass of the flocculent carbon fibers. The viscosity of the liquid composition when mixed with the flocculent carbon fibers is preferably 10 Pa s or less.

[0022] The carbon fiber agglomerates are formed by the aggregation of fiber filaments due to capillary forces generated by the presence of the liquid composition. The liquid composition remains in the formed carbon fiber agglomerates as a resin matrix. After the carbon fiber agglomerates are formed, the liquid composition may thicken or solidify.

[0023] The liquid composition contains a thermosetting resin and a curing agent thereof. Examples of the thermosetting resin include unsaturated polyester resin, vinyl ester resin, cyanate resin, and epoxy resin.

[0024] Examples of optional components that the liquid composition may contain include reactive diluents, thickeners, polymerization inhibitors, low-shrinkage agents, flame retardants, antifoaming agents, antioxidants, internal mold release agents, colorants, modifiers (e.g., rubber, elastomer, or thermoplastic resin), and antibacterial agents.

[0025] In the impregnated carbon fiber agglomerate, all or almost all of the contained fiber filaments may be aggregated so as to be parallel to one another, in other words, all or almost all of the contained fiber filaments may form a single bundle.

[0026] The "carbon fiber bundle composite" described in the aforementioned Patent Document 1 is a type of the impregnated carbon fiber agglomerate referred to in this specification.

[0027] (3) Carbon Fiber-Containing Fiber Agglomerates Another example of particles that can constitute the particulate molding material is a fiber agglomerate containing carbon fiber, thermoplastic polymer fiber, and a binder. In this specification, such a fiber agglomerate is referred to as a "carbon fiber-containing fiber agglomerate."

[0028] The carbon fiber-containing fiber agglomerate can be obtained by mixing cotton-like carbon fiber, thermoplastic polymer fiber, and a binder-containing liquid in a ratio of, for example, 25 to 150 parts by mass of the binder-containing liquid per 100 parts by mass of the total amount of cotton-like carbon fiber and thermoplastic polymer fiber, and then drying the wet fiber agglomerate.

[0029] The fiber agglomerates are formed by the aggregation of fiber filaments due to capillary forces generated by the presence of a binder-containing liquid. The binder-containing liquid is a liquid in which a binder is dispersed and / or dissolved. The binder-containing liquid is preferably water in which a binder is dispersed and / or dissolved.

[0030] Examples of the polymer contained in the thermoplastic polymer fibers include polypropylene, polysulfone, polyethersulfone, polyetherketone, polyetheretherketone, aromatic polyamide, aliphatic polyamide, aromatic polyesters such as polybutylene terephthalate and polyethylene terephthalate, aromatic polycarbonate, polyetherimide, polyarylene oxide, polyarylene sulfide, thermoplastic polyimide, polyamideimide, polyethylene, ethylene-vinyl alcohol copolymer, and acrylonitrile butadiene styrene, as well as linear polymers of difunctional epoxy compounds.

[0031] The thermoplastic polymer fibers may be used singly or in combination of two or more types of thermoplastic polymer fibers.

[0032] The filament length of the thermoplastic polymer fiber is, for example, within the range of 5 to 100 mm. The filament length of the thermoplastic polymer fiber preferably does not exceed the length of the longest carbon fiber filament contained in the cotton-like carbon fiber.

[0033] The binder serves to bind the fiber filaments together so that the carbon fiber-containing fiber agglomerate can maintain its shape. A sizing agent applied to typical PAN-based carbon fiber tows is a suitable example of the binder.

[0034] Examples of materials that the binder may contain include epoxy resins, urethane-modified epoxy resins, polyester resins, phenolic resins, polyamides, polyurethanes, polyvinyl alcohol, polyvinylpyrrolidone, carboxymethyl cellulose, sodium alginate, and polyacrylamides.

[0035] The ratio of carbon fiber to the total amount of carbon fiber and thermoplastic polymer fiber contained in the carbon fiber-containing fiber agglomerate is preferably 20 to 60 mass %, although the ratio of carbon fiber to the total amount of carbon fiber and thermoplastic polymer fiber is not limited to this range.

[0036] In the carbon fiber-containing fiber agglomerate, all or almost all of the contained fiber filaments may be aggregated so as to be parallel to one another, in other words, all or almost all of the contained fiber filaments may form a single bundle.

[0037] Among the "self-assembled fiber bundles consisting of a plurality of inorganic fibers, a plurality of organic fibers, and an organic binder" described in the aforementioned Patent Document 3, those containing carbon fibers as the inorganic fibers and thermoplastic polymer fibers as the organic fibers are a type of carbon fiber-containing fiber agglomerate referred to in this specification.

[0038] 1.2. Flocculent Carbon Fibers Preferred examples of flocculent carbon fibers that can be used to produce the impregnated carbon fiber agglomerates and carbon fiber-containing fiber agglomerates are described below.

[0039] The purest flocculent carbon fiber consists of only a plurality of carbon fiber filaments that are not bonded to one another. However, the flocculent carbon fiber used to produce the impregnated carbon fiber agglomerates or carbon fiber-containing fiber agglomerates may contain impurities to the extent that they do not cause any problems. Examples of impurities include fine carbon fiber bundles in which a plurality of carbon fiber filaments are bonded to one another, and fiber filaments other than carbon fiber filaments, such as glass fiber filaments.

[0040] The flocculent carbon fiber preferably contains carbon fiber filaments having a length of 5 mm or more, more preferably 10 mm or more, and even more preferably 20 mm or more. The flocculent carbon fiber preferably contains carbon fiber filaments having a length of 100 mm or less, more preferably 60 mm or less, even more preferably 40 mm or less, and even more preferably 30 mm or less. In one example, all of the carbon fiber filaments contained in the flocculent carbon fiber may have a length of 100 mm or less, further 60 mm or less, further 40 mm or less, or even 30 mm or less.

[0041] 1.3 Recycled Carbon Fiber The granular molding material may contain recycled carbon fiber recovered from CFRP or carbon fiber prepreg. There are no limitations on the method for removing the resin matrix from CFRP or carbon fiber prepreg to obtain recycled carbon fiber, and any method can be used, including pyrolysis, a method using a supercritical fluid, a method using superheated steam, a chemical decomposition method, an electrolytic oxidation method, and a method using active oxygen.

[0042] In order to obtain cotton-like recycled carbon fibers in which the carbon fiber filaments are not bonded to each other, it is effective to remove most of the resin matrix and then remove the residual carbon by heating in an oxidizing atmosphere. In one example, recycled carbon fibers containing carbon fiber filaments bonded to each other by the residual carbon may be made cotton-like by mechanically loosening them.

[0043] Recycled carbon fibers obtained from CFRP molded from SMC (sheet molding compound) or SMC scraps often contain only carbon fibers with filament lengths of 60 mm or less, and can be used to produce impregnated carbon fiber agglomerates and carbon fiber-containing fiber agglomerates without further cutting.

[0044] Recycled carbon fibers obtained from CFRP products manufactured using UD prepregs, fabric prepregs, or tow prepregs, or recycled carbon fibers obtained from CFRP products manufactured by the RTM method, VaRTM method, filament winding method, or pultrusion method, may be cut, as needed, to form carbon fiber filaments of a length suitable for manufacturing impregnated carbon fiber agglomerates and carbon fiber-containing fiber agglomerates.

[0045] In a method in which a CFRP product is crushed using a uniaxial, biaxial, or quadriaxial crusher and then the polymer matrix is ​​removed, the carbon fibers contained therein are cut when the CFRP product is crushed. When the dimensions of the crushed pieces produced by crushing are 60 mm or less in any direction, almost all of the carbon fibers contained in the crushed pieces are cut to filament lengths of 60 mm or less. If the crushed pieces that are less than 5 mm in any direction are removed by sieving and then the polymer matrix is ​​removed, recycled carbon fiber with a reduced content of carbon fibers with filament lengths of less than 5 mm can be obtained.

[0046] 1.4. Particle Shape The granular molding material may contain elongated particles, such as strips, needles, spindles, or wires. The chopped carbon fiber tow prepreg is often strip-shaped. The impregnated carbon fiber agglomerates and carbon fiber-containing fiber agglomerates exhibit needle, spindle, or wire shapes when all or almost all of the contained fiber filaments are aggregated so that they are parallel to one another. This type of aggregation is likely to occur when the carbon fiber contains fiber filaments with a length of 5 mm or more. Elongated particles tend to curve along their longitudinal direction as their length increases. This tendency becomes stronger when the particle length is 20 mm or more, especially when it is 30 mm or more.

[0047] Granular molding materials containing elongated particles are prone to bridging, making continuous, metered feeding difficult using a hopper feeder. This tendency becomes more pronounced as the length of the particles increases. When granular molding materials contain elongated particles that are curved along their longitudinal direction, it also becomes difficult to meter them using a screw conveyor or vibrating conveyor. This is because the curved particles tend to become entangled when the granular molding material is compressed in the feeder.

[0048] From the above, it can be seen that supplying a granular molding material using the method according to an embodiment of the present invention is particularly advantageous when the granular molding material contains elongated particles. Supplying a granular molding material using the method according to an embodiment of the present invention is even more advantageous when at least some of the particles are curved along the longitudinal direction. In other words, supplying a granular molding material using the method according to an embodiment of the present invention is even more advantageous when the granular molding material contains elongated particles having a length of 20 mm or more.

[0049] 1.5 Others A granular molding material does not necessarily have to be composed of particles of the same type. Thus, an example granular molding material may contain chopped carbon fiber tow prepreg and impregnated carbon fiber agglomerates.

[0050] 2. Method for Supplying Granular Molding Material Containing Carbon Fiber One embodiment of the present invention relates to a method for supplying a granular molding material containing carbon fiber. This method will be described in detail below using as an example the case where it is applied to the production of a resin sheet containing carbon fiber.

[0051] Hereinafter, the "method for supplying a granular molding material containing carbon fiber" may be simply referred to as the "supply method." When simply referring to the "supply method" below, it means the "method for supplying a granular molding material containing carbon fiber" unless otherwise specified.

[0052] Hereinafter, the "carbon fiber-containing resin sheet" may be simply referred to as the "resin sheet." Hereinafter, when simply referring to the "resin sheet," it means the "carbon fiber-containing resin sheet" unless otherwise specified.

[0053] 2.1 Resin Sheet Manufacturing Apparatus An example of a manufacturing apparatus that can be preferably used when manufacturing a resin sheet using the supply method according to the embodiment is shown in FIG.

[0054] Referring to FIG. 1 , a resin sheet manufacturing apparatus 1 includes a first belt conveyor 10 , a scraping roller 20 , a rod 30 , a second belt conveyor 40 , and a double belt press 50 .

[0055] The first belt conveyor 10 is an example of a belt conveyor having an upward gradient portion, and is an inclined belt conveyor having only an upward gradient portion. In a modified example, the first belt conveyor 10 may have a horizontal portion on either or both the upstream side and downstream side of the upward gradient portion.

[0056] The conveying surface 11a of the conveyor belt 11 of the first belt conveyor 10, i.e., the surface on which the granular molding material 2 is placed, is an uneven surface. This is to prevent the granular molding material 2 to be conveyed from sliding down the conveying surface 11a of the conveyor belt 11 on the upward slope of the first belt conveyor 10.

[0057] The conveying surface 11a of the conveyor belt 11 may be an uneven surface having a recess having a bottom surface and a protrusion protruding from the bottom surface, as shown in the cross-sectional view of FIG. 2, for example. In this case, the proportion of the area occupied by the protrusions when the uneven surface is viewed in plan is preferably 50% or less, more preferably 10% or less. In one example, the protrusions in such an uneven surface may be walls perpendicular to the bottom surface of the recess. Such walls may be parallel to the width direction of the conveyor belt. In another example, the protrusions in such an uneven surface may be columnar. The columnar protrusions may be perpendicular to the bottom surface of the recess, or may be inclined toward the running direction of the first conveyor belt.

[0058] In a preferred example, the conveyor belt 11 may be a spiked lattice. Figure 3 is a side view showing an example of a spiked lattice. In the spiked lattice, the slat width is preferably 5 to 30 mm, and the spike length is preferably 5 to 20 mm. In the spiked lattice conveyor belt, the surface with the spikes is the conveying surface.

[0059] The scraping roller 20 is an example of a scraping means for scraping off a portion of the granular molding material 2 being transported by the first belt conveyor 10, and is optionally provided midway along the upward slope of the first belt conveyor 10 or at the top end thereof. The scraping roller 20 has a rotation axis parallel to the T direction of the first belt conveyor 10 and a cylinder with the rotation axis as its central axis, and a plurality of blades, each parallel to the rotation axis, are arranged on the outer circumferential surface of the cylinder.

[0060] Here, the T direction of the belt conveyor means a horizontal direction perpendicular to the conveying direction of the belt conveyor. The T direction of the belt conveyor usually coincides with the width direction of the conveyor belt of the belt conveyor. If the conveyor belt is a spiked lattice, the longitudinal direction of the slats coincides with the T direction of the belt conveyor.

[0061] The rod 30 is an example of a dispersing means for dispersing the granular molding material 2 dropping from the discharge end 10E of the first belt conveyor 10, and is optionally disposed below the discharge end 10E. The rod 30 is a rod supported so that its longitudinal direction is horizontal or oblique, and its cross-sectional shape is not limited to a circle but may be a polygon such as a triangle, a rectangle, or a hexagon.

[0062] The rod 30 is reciprocated or circularly moved by a drive mechanism (not shown). When the rod 30 is reciprocated, the direction of the reciprocating motion includes a component inclined with respect to the longitudinal direction of the rod 30 and a horizontal component. In a preferred embodiment, the rod 30 is reciprocated horizontally along a direction perpendicular to its longitudinal direction. When the rod 30 is circularly moved, the longitudinal direction of the rod 30 is kept constant, and the trajectory of the circular motion is not parallel to a vertical plane parallel to the longitudinal direction of the rod 30. In a preferred embodiment, the trajectory of the circular motion is horizontal.

[0063] Typically, a lattice is formed by the plurality of rods 30. In other words, the plurality of rods 30 are arranged at equal intervals in the same plane.

[0064] In a preferred example, as shown in Figure 4, the first lattice L1 and the second lattice L2 are arranged so as to be stacked one on top of the other. The first lattice L1, which is made up of a plurality of rods 31, is arranged so that the rods 31 are horizontal and perpendicular to the T direction of the first belt conveyor 10. The second lattice L2, which is made up of a plurality of rods 32, is arranged so that the rods 32 are horizontal and parallel to the T direction of the first belt conveyor 10. Either the first lattice L1 or the second lattice L2 may be on top or bottom.

[0065] Other examples of dispersing means for dispersing the granular molding material 2 dropping from the discharge end 10E of the first belt conveyor 10 include grids and punched metal. The grid may be an expanded metal. The grid and punched metal are also reciprocated or circularly moved by a drive mechanism. In the case of reciprocating movement, the direction of movement is preferably horizontal. In the case of circular movement, the trajectory is preferably horizontal.

[0066] The second belt conveyor 40 is a horizontal belt conveyor with no inclined portion in the conveying path. The second belt conveyor 40 is optionally arranged downstream of the first belt conveyor 10. The T direction of the second belt conveyor 40 is the same as the T direction of the first belt conveyor 10.

[0067] It is preferable, but not essential, that the conveying path of the second belt conveyor 40 be horizontal. Even if the second belt conveyor 40 has a slope, it is acceptable as long as the slope is not so steep that the granular molding material 2 being conveyed on the conveyor belt 41 moves due to gravity.

[0068] The granular molding material 2 dropping from the discharge end 10E of the first belt conveyor 10 drops onto the second belt conveyor 40 and is transported toward the discharge end 40E. The belt running speed v2 of the second belt conveyor 40 is preferably equal to or less than the belt running speed v1 of the first belt conveyor 10, and more preferably lower than the belt running speed v1 of the first belt conveyor 10.

[0069] The discharge end 40E of the second belt conveyor 40 is disposed above the path of the first carrier film 3, which runs along the longitudinal direction of the second belt conveyor 40. The granular molding material 2 falls from the discharge end 40E of the second belt conveyor 40 onto the first carrier film 3, and forms a deposit layer 5 on the first carrier film 3.

[0070] The width direction of the first carrier film 3 is parallel to the T direction of the second belt conveyor 40. In the area where the granular molding material 2 falls, the upper surface of the first carrier film 3 is held horizontal. The running speed v3 of the first carrier film 3 is preferably equal to or less than the belt running speed v2 of the second belt conveyor 40, and more preferably lower than the belt running speed v2 of the second belt conveyor 40.

[0071] If the second belt conveyor 40 is not provided, the granular molding material 2 is dropped onto the first carrier film 3 from the discharge end 10E of the first belt conveyor 10 to form the deposit layer 5. In such a case, the running speed v3 of the first carrier film 3 is preferably equal to or less than the belt running speed v1 of the first belt conveyor 10, and more preferably lower than the belt running speed v1 of the first belt conveyor 10.

[0072] After the deposition layer 5 is formed on the first carrier film 3, the second carrier film 4 is superimposed on the first carrier film 3, and the deposition layer 5 is sandwiched between the first carrier film 3 and the second carrier film 4.

[0073] The double belt press 50 includes a lower conveyor belt 52 and an upper conveyor belt 54, as well as rolls for compressing the deposited layer 5 sandwiched between two carrier films 3 and 4 by sandwiching the lower conveyor belt 52 and the upper conveyor belt 54 together.

[0074] At least some of the rolls included in the double belt press 50 may be heating rolls. Also, at least some of the rolls included in the double belt press 50 may be cooling rolls. The resin sheet manufacturing apparatus may be provided with a far-infrared heater for heating the deposition layer 5 before compressing it with the double belt press 50.

[0075] 2.2 Manufacturing Method of Resin Sheet Next, a manufacturing method of a resin sheet using the supply method according to the embodiment will be described using an example in which the resin sheet manufacturing apparatus 1 shown in FIG. 1 is used.

[0076] In this method, first, the granular molding material 2 is supplied to the bottom of the first belt conveyor 10. The means for supplying the granular molding material 2 to the bottom of the first belt conveyor 10 may include any conveying device including a belt conveyor, a screw conveyor, and a vibrating conveyor.

[0077] The granular molding material 2 supplied to the bottom of the first belt conveyor 10 is conveyed by the first belt conveyor 10 toward the discharge end 10E, which is the end of its upwardly inclined portion. If the inclination of the upwardly inclined portion is sufficiently steep, the amount of granular molding material 2 that reaches the discharge end 10E of the first belt conveyor 10 per unit time is limited. This is because the amount of granular molding material 2 that passes through the upwardly inclined portion while remaining on the conveying surface 11a of the conveyor belt 11 is limited. The amount of granular molding material 2 that can remain on the conveying surface 11a of the conveyor belt 11 in the upwardly inclined portion is determined by the balance between the frictional forces acting between the particles contained in the granular molding material 2 and gravity.

[0078] Since there is an upper limit to the amount of granular molding material 2 that can reach the discharge end 10E of the first belt conveyor 10, the amount of granular molding material 2 discharged from the discharge end 10E of the first belt conveyor 10 per unit time is constant. In other words, it is possible to supply a fixed amount of granular molding material 2 to the downstream side of the first belt conveyor 10.

[0079] By rotating the scraping roller 20, which is optionally provided, it is possible to further reduce the variation in the amount of granular molding material 2 that reaches the discharge end 10E of the first belt conveyor 10 per unit time. This is because when the height of the granular molding material 2 on the first conveyor belt 11 exceeds the gap between the scraping roller 20 and the first conveyor belt 11, part of the granular molding material 2 is scraped off by the scraping roller 20.

[0080] The granular molding material 2 can be dropped evenly onto the second belt conveyor 20 by horizontally reciprocating the rod 30 arranged optionally in a direction perpendicular to its longitudinal direction.

[0081] When the belt running speed v2 of the second belt conveyor 40 is lower than the belt running speed v1 of the first belt conveyor 10, the variation in the amount of granular molding material 2 transported by the second belt conveyor 40 per unit time can be smaller than the variation in the amount of granular molding material 2 discharged from the first belt conveyor 10 per unit time.

[0082] The granular molding material 2 falls from the discharge end 40E of the second belt conveyor 40 onto the first carrier film 3 traveling underneath, and forms a deposit layer 5 on the first carrier film 3.

[0083] When the running speed v3 of the first carrier film 3 is lower than the belt running speed v2 of the second belt conveyor 40, the variation in the amount of granular molding material 2 carried by the first carrier film 3 per unit time can be smaller than the variation in the amount of granular molding material 2 discharged from the second belt conveyor 40 per unit time. Here, the amount of granular molding material 2 carried by the first carrier film 3 per unit time can be rephrased as the mass of the deposited layer 5 per unit length along the running direction of the first carrier film 3.

[0084] The deposition layer 5 is sandwiched between the first carrier film 3 and the second carrier film 4 and then compressed by the double belt press 50. This causes the particles contained in the granular molding material 2 that form the deposition layer 5 to fuse together, forming a resin sheet. The deposition layer 5 is heated to a temperature at which the fusion becomes possible. The heating means may be a heating roll provided in the double belt press 50, or a far-infrared heater provided in the resin sheet manufacturing apparatus.

[0085] When the particles constituting the granular molding material 2 are impregnated carbon fiber agglomerates and the thermosetting resin matrix contained in the particles is a liquid having a viscosity of, for example, less than 1000 Pa·s at 25°C, heating is not necessarily required to fuse the particles together.

[0086] The formed resin sheet is wound up on a bobbin while sandwiched between the first carrier film 3 and the second carrier film 4. However, winding up on a bobbin is not essential. In one example, the formed resin sheet may be folded and stored in a container. In another example, the formed resin sheet may be cut into a size that is easy to transport and stored in a container.

[0087] In one alternative embodiment, the second belt conveyor 40 may be omitted and the granular molding material 2 may be dropped onto the first carrier film 3 from the discharge end 10E of the first belt conveyor 10 to form the deposition layer 5.

[0088] In another modified embodiment, the use of the first carrier film 3 and the second carrier film 4 may be omitted. That is, the deposited layer 5 may be formed directly on the lower conveyor belt 52 of the double belt press 50, and the deposited layer 5 may be directly sandwiched between the lower conveyor belt 52 and the upper conveyor belt 54.

[0089] 2.3 Resin Sheet By using the method described in 2.2 above, a resin sheet can be obtained in which fluctuations in weight per unit length along the M direction are suppressed. The M direction here refers to a direction parallel to the direction of movement of the resin sheet material when it passes through the double belt press (the running direction of the conveyor belt of the double belt press).

[0090] The thickness of the resin sheet may be, for example, within a range of 1 mm to 5 mm. However, the thickness of the resin sheet is not limited to this range. The width of the resin sheet (the dimension in the direction perpendicular to the M direction) may be, for example, within a range of 0.3 m to 3 m. However, the width of the resin sheet is not limited to this range.

[0091] Resin sheets are used as molding materials (intermediate materials) when producing CFRP products by, for example, compression molding. CFRP products molded using resin sheets have a wide range of uses, including parts for aircraft, automobiles, ships, and other transportation equipment, as well as sporting goods and leisure goods.

[0092] 3. Summary of Embodiments Embodiments of the present invention include those described in the following items. [Item 1] A method for continuously supplying a granular molding material containing carbon fiber, comprising conveying the granular molding material to a discharge end of a first belt conveyor having a conveyor belt with an uneven transport surface and an upwardly sloping section. [Item 2] The method described in Item 1, wherein the transport surface is an uneven surface having concave portions with bottom surfaces and convex portions protruding from the bottom surface, and wherein, when the convex and concave surfaces are viewed from above, the convex portions account for 50% or less, preferably 10% or less, of the area of ​​the uneven surface. [Item 3] The method described in Item 1, wherein the conveyor belt is a spiked lattice. [Item 4] The method described in any one of Items 1 to 3, wherein the steepness of the upwardly sloping section limits the amount of the granular molding material that reaches the discharge end of the first belt conveyor per unit time. [Item 5] The method of any one of Items 1 to 4, further comprising using a scraping means to scrape off a portion of the granular molding material being conveyed by the first belt conveyor midway through or at the top end of the upwardly sloping section. [Item 6] The method of Item 5, wherein the scraping means comprises a scraping roller having a rotation axis parallel to the T direction of the first belt conveyor, a cylindrical portion whose central axis is the rotation axis, and a plurality of blades disposed on the outer circumferential surface of the cylindrical portion, each blade being parallel to the rotation axis. [Item 7] The method of any one of Items 1 to 6, further comprising causing the granular molding material to fall from the discharge end of the first belt conveyor. [Item 8] The method of any one of Items 1 to 7, wherein a dispersing means capable of reciprocating or circular motion is disposed below the discharge end of the first belt conveyor to disperse the granular molding material. [Item 9] The method of Item 8, wherein the dispersing means comprises a rod that is reciprocated horizontally along a direction perpendicular to its longitudinal direction. [Item 10] The granular molding material is dropped from the discharge end of the first belt conveyor onto a second belt conveyor that is in the same T direction as the first belt conveyor and is preferably a horizontal belt conveyor. The method according to any one of items 1 to 9.[Item 11] The method according to Item 10, wherein the belt running speed of the second belt conveyor is lower than the belt running speed of the first belt conveyor. [Item 12] The method according to any one of Items 1 to 11, wherein the granular molding material comprises elongated particles. [Item 13] The method according to Item 12, wherein the elongated particles have the shape of a strip, needle, spindle, or wire. [Item 14] The method according to Item 12 or 13, wherein the elongated particles are curved along the longitudinal direction. [Item 15] The method according to any one of Items 12 to 14, wherein the length of the elongated particles is 20 mm or more. [Item 16] The method according to any one of Items 1 to 11, wherein the granular molding material comprises chopped carbon fiber tow prepreg. [Item 17] The method according to Item 16, wherein the chopped carbon fiber tow prepreg has the shape of a strip. [Item 18] The method according to Item 16 or 17, wherein the chopped carbon fiber tow prepreg is curved along the longitudinal direction. [Item 19] The method according to any one of Items 16 to 18, wherein the length of the chopped carbon fiber tow prepreg is 20 mm or more. [Item 20] The method according to any one of Items 1 to 11, wherein the granule molding material comprises impregnated carbon fiber agglomerates, and the impregnated carbon fiber agglomerates are carbon fiber agglomerates impregnated with a thermosetting resin matrix. [Item 21] The method according to Item 20, wherein the impregnated carbon fiber agglomerates have an elongated shape, which may be a needle, spindle, or wire shape. [Item 22] The method according to Item 21, wherein the carbon fiber agglomerates are curved along the longitudinal direction. [Item 23] The method according to Item 21 or 22, wherein the length of the carbon fiber agglomerates is 20 mm or more. [Item 24] The method according to any one of Items 1 to 11, wherein the granule molding material comprises carbon fiber-containing agglomerates, and the carbon fiber-containing agglomerates are fiber agglomerates containing carbon fibers, thermoplastic polymer fibers, and a binder. [Item 25] The method according to Item 24, wherein the carbon fiber-containing fiber agglomerate has an elongated shape, which may be a needle, a spindle, or a wire. [Item 26] The method according to Item 25, wherein the carbon fiber-containing fiber agglomerate is curved along its longitudinal direction.[Item 27] ​​The method according to Item 25 or 26, wherein the length of the carbon fiber-containing fiber agglomerates is 20 mm or more.

[0093] [Item 28] A method for producing a resin sheet containing carbon fiber, comprising: a first step of continuously supplying a granular molding material containing carbon fiber to a double belt press; and a second step of fusing particles contained in the granular molding material to form a sheet using the double belt press, wherein the first step comprises conveying the granular molding material to a discharge end of a first belt conveyor having a conveyor belt with an uneven transport surface and an upwardly sloping section. [Item 29] The method according to Item 28, wherein the transport surface is an uneven surface having a concave portion having a bottom surface and a convex portion protruding from the bottom surface, and wherein the convex portion occupies 50% or less, preferably 10% or less, of the area of ​​the uneven surface when viewed from above. [Item 30] The method according to Item 28, wherein the conveyor belt is a spiked lattice. [Item 31] The method according to any one of Items 28 to 30, wherein the steepness of the upwardly sloping section limits the amount of the granular molding material reaching the discharge end of the first belt conveyor per unit time. [Item 32] The method of any one of Items 28 to 31, further comprising using a scraping means to scrape off a portion of the granular molding material being conveyed by the first belt conveyor midway through or at the top end of the upwardly sloping section. [Item 33] The method of Item 32, wherein the scraping means comprises a scraping roller having a rotation axis parallel to the T direction of the first belt conveyor, a cylindrical portion whose central axis is the rotation axis, and a plurality of blades disposed on the outer circumferential surface of the cylindrical portion, each blade being parallel to the rotation axis. [Item 34] The method of any one of Items 28 to 33, further comprising dropping the granular molding material from the discharge end of the first belt conveyor. [Item 35] The method of any one of Items 28 to 34, wherein a dispersing means capable of reciprocating or circular motion is disposed below the discharge end of the first belt conveyor to disperse the granular molding material. [Item 36] The method of Item 35, wherein the dispersing means comprises a rod that is reciprocated horizontally along a direction perpendicular to its longitudinal direction.[Item 37] The method of any one of Items 28 to 36, which includes dropping the granular molding material from the discharge end of the first belt conveyor onto a second belt conveyor, which is preferably a horizontal belt conveyor and has the same T direction as the first belt conveyor. [Item 38] The method of Item 37, wherein the belt running speed of the second belt conveyor is lower than the belt running speed of the first belt conveyor. [Item 39] The method of any one of Items 28 to 38, wherein the granular molding material comprises elongated particles. [Item 40] The method of Item 39, wherein the elongated particles have the shape of a strip, needle, spindle, or wire. [Item 41] The method of Items 39 or 40, wherein the elongated particles are curved along the longitudinal direction. [Item 42] The method of any one of Items 39 to 41, wherein the length of the elongated particles is 20 mm or more. [Item 43] The method of any one of Items 28 to 38, wherein the granular molding material comprises chopped carbon fiber tow prepreg. [Item 44] The method of item 43, wherein the chopped carbon fiber tow prepreg has a strip shape. [Item 45] The method of item 43 or 44, wherein the chopped carbon fiber tow prepreg is curved along the longitudinal direction. [Item 46] The method of any one of items 43 to 45, wherein the length of the chopped carbon fiber tow prepreg is 20 mm or more. [Item 47] The method of any one of items 28 to 38, wherein the granule molding material comprises impregnated carbon fiber agglomerates, and the impregnated carbon fiber agglomerates are carbon fiber agglomerates impregnated with a thermosetting resin matrix. [Item 48] The method of item 47, wherein the impregnated carbon fiber agglomerates have an elongated shape, which may be a needle, spindle, or wire shape. [Item 49] The method of item 48, wherein the carbon fiber agglomerates are curved along the longitudinal direction. [Item 50] The method of item 48 or 49, wherein the length of the carbon fiber agglomerates is 20 mm or more. [Item 51] The method according to any one of Items 28 to 38, wherein the particulate molding material comprises a carbon fiber-containing agglomerate, and the carbon fiber-containing agglomerate is a fiber agglomerate containing carbon fiber, thermoplastic polymer fiber, and a binder.[Item 52] The method according to Item 51, wherein the carbon fiber-containing fiber agglomerate has an elongated shape, which may be a needle, spindle, or wire. [Item 53] The method according to Item 52, wherein the carbon fiber-containing fiber agglomerate is curved along the longitudinal direction. [Item 54] The method according to Item 52 or 53, wherein the length of the carbon fiber-containing fiber agglomerate is 20 mm or more.

[0094] [Item 55] An apparatus for manufacturing a resin sheet containing carbon fiber, comprising: a double belt press for fusing particles contained in a granular molding material containing carbon fiber to form a sheet; and a first belt conveyor having a conveyor belt with an uneven transport surface and an upwardly inclined portion for supplying the granular molding material to the double belt press. [Item 56] The apparatus described in Item 55, wherein the transport surface is an uneven surface having a concave portion having a bottom surface and a convex portion protruding from the bottom surface, and when the convex portion is viewed from above, the proportion of the area occupied by the convex portion of the uneven surface is 50% or less, preferably 10% or less. [Item 57] The apparatus described in Item 55, wherein the conveyor belt is a spiked lattice. [Item 58] The apparatus described in any one of Items 55 to 57, wherein the steepness of the upwardly inclined portion limits the amount of the granular molding material reaching the discharge end of the first belt conveyor per unit time. [Item 59] The apparatus according to any one of Items 55 to 58, further comprising scraping means for scraping off a portion of the granular molding material conveyed by the first belt conveyor midway through or at the top end of the upwardly inclined portion. [Item 60] The apparatus according to Item 59, wherein the scraping means comprises a scraping roller having a rotation axis parallel to the T direction of the first belt conveyor, a cylindrical portion whose central axis is the rotation axis, and a plurality of blades disposed on the outer circumferential surface of the cylindrical portion, each blade being parallel to the rotation axis. [Item 61] The apparatus according to any one of Items 55 to 60, wherein dispersing means capable of reciprocating or circular motion is disposed below the discharge end of the first belt conveyor for dispersing the granular molding material dropping from the discharge end of the first belt conveyor. [Item 62] The apparatus according to Item 61, wherein the dispersing means comprises a rod that is reciprocated horizontally along a direction perpendicular to its longitudinal direction.

[0095] The present invention has been described above with reference to specific embodiments. However, each embodiment is presented as an example and does not limit the scope of the present invention. Each embodiment described in this specification can be modified in various ways within the scope of the effects of the invention and can be combined with features described in other embodiments to the extent possible. This application is based on Japanese Patent Application No. 2024-010347, filed on January 26, 2024, and is incorporated by reference in its entirety.

[0096] REFERENCE SIGNS LIST 1 Resin sheet manufacturing apparatus 2 Granular molding material containing carbon fiber 10 First belt conveyor 11 Conveyor belt 11a Conveying surface 20 Scraper roller 30 Rod 40 Second belt conveyor 50 Double belt press

Claims

1. A method for continuously supplying a granular molding material containing carbon fibers, comprising conveying the granular molding material to its discharge end using a first belt conveyor having a conveyor belt with an uneven surface and an upward sloping section.

2. The method according to claim 1, wherein the conveying surface is an uneven surface having a recess with a bottom surface and a protrusion protruding from the bottom surface, and when the uneven surface is viewed from above, the proportion of the area occupied by the protrusion on the uneven surface is 50% or less, preferably 10% or less.

3. The method according to claim 1, wherein the conveyor belt is a lattice with spikes.

4. The method according to any one of claims 1 to 3, wherein the steep incline of the upward sloping section limits the amount of granular molding material that reaches the discharge end of the first belt conveyor in a unit time.

5. The method according to any one of claims 1 to 3, further comprising scraping off a portion of the granular molding material being transported by the first belt conveyor using a scraping means at the middle or upper end of the upward sloping section.

6. The method according to claim 5, wherein the scraping means includes a scraping roller, and the scraping roller has a rotation axis parallel to the T direction of the first belt conveyor, a cylindrical portion with the rotation axis as its central axis, and a plurality of blades arranged on the outer circumferential surface of the cylindrical portion, each parallel to the rotation axis.

7. The method according to any one of claims 1 to 3, comprising dropping the granular molding material from the discharge end of the first belt conveyor.

8. The method according to any one of claims 1 to 3, wherein a dispersion means that is moved in a reciprocating or circular motion for dispersing the granular molding material is disposed below the discharge end of the first belt conveyor.

9. The method according to claim 8, wherein the dispersion means includes a rod, and the rod is moved horizontally back and forth along a direction perpendicular to its longitudinal direction.

10. The method according to any one of claims 1 to 3, comprising dropping the granular molding material from the discharge end of the first belt conveyor onto a second belt conveyor which has the same T-direction as the first belt conveyor and is preferably a horizontal belt conveyor.

11. The method according to claim 10, wherein the belt travel speed of the second belt conveyor is lower than the belt travel speed of the first belt conveyor.

12. The method according to any one of claims 1 to 3, wherein the granular molding material includes particles with an elongated shape.

13. The method according to claim 12, wherein the elongated particles have the shape of a strip, needle, spindle, or wire.

14. The method according to claim 12, wherein the elongated particle is curved along its longitudinal direction.

15. The method according to claim 12, wherein the length of the elongated particle is 20 mm or more.

16. The method according to any one of claims 1 to 3, wherein the granular molding material includes chopped carbon fiber tow prepreg.

17. The method according to claim 16, wherein the shape of the chopped carbon fiber tow prepreg is a strip.

18. The method according to claim 16, wherein the chopped carbon fiber tow prepreg is curved along the longitudinal direction.

19. The method according to claim 16, wherein the length of the chopped carbon fiber tow prepreg is 20 mm or more.

20. The method according to any one of claims 1 to 3, wherein the granular molding material includes an impregnated carbon fiber aggregate, and the impregnated carbon fiber aggregate is a carbon fiber aggregate impregnated with a thermosetting resin matrix.

21. The method according to claim 20, wherein the impregnated carbon fiber aggregate has a long, elongated shape, and the shape may be a needle, a spindle, or a wire.

22. The method according to claim 21, wherein the carbon fiber aggregate is curved along the longitudinal direction.

23. The method according to claim 21, wherein the length of the carbon fiber aggregate is 20 mm or more.

24. The method according to any one of claims 1 to 3, wherein the granular molding material includes a carbon fiber-containing fiber aggregate, and the carbon fiber-containing aggregate is a fiber aggregate containing carbon fibers, thermoplastic polymer fibers, and a binder.

25. The method according to claim 24, wherein the carbon fiber-containing fiber aggregate has an elongated shape, and the shape may be a needle, a spindle, or a wire.

26. The method according to claim 25, wherein the carbon fiber-containing fiber aggregate is curved along the longitudinal direction.

27. The method according to claim 25, wherein the length of the carbon fiber-containing fiber aggregate is 20 mm or more.

28. A method for manufacturing a resin sheet containing carbon fibers, comprising: a first step of continuously supplying a granular molding material containing carbon fibers to a double belt press; and a second step of fusing particles contained in the granular molding material together with the double belt press to form a sheet, wherein the first step includes transporting the granular molding material to its discharge end using a first belt conveyor having a conveyor belt with an uneven surface and an upward sloping section.

29. The method according to claim 28, wherein the conveying surface is an uneven surface having a recess with a bottom surface and a protrusion protruding from the bottom surface, and when the uneven surface is viewed from above, the proportion of the area occupied by the protrusion on the uneven surface is 50% or less, preferably 10% or less.

30. The method according to claim 28, wherein the conveyor belt is a lattice with spikes.

31. The method according to any one of claims 28 to 30, wherein the steep incline of the upward sloping portion limits the amount of granular molding material that reaches the discharge end of the first belt conveyor in a unit time.

32. The method according to any one of claims 28 to 30, further comprising scraping off a portion of the granular molding material being transported by the first belt conveyor using a scraping means at the middle or upper end of the upward sloping section.

33. The method according to claim 32, wherein the scraping means includes a scraping roller, and the scraping roller has a rotation axis parallel to the T direction of the first belt conveyor, a cylindrical portion with the rotation axis as its central axis, and a plurality of blades arranged on the outer circumferential surface of the cylindrical portion, each parallel to the rotation axis.

34. The method according to any one of claims 28 to 30, comprising dropping the granular molding material from the discharge end of the first belt conveyor.

35. The method according to any one of claims 28 to 30, wherein a dispersion means that is moved in a reciprocating or circular motion for dispersing the granular molding material is disposed below the discharge end of the first belt conveyor.

36. The method according to claim 35, wherein the dispersion means includes a rod, and the rod is moved horizontally back and forth along a direction perpendicular to its longitudinal direction.

37. The method according to any one of claims 28 to 30, comprising dropping the granular molding material from the discharge end of the first belt conveyor onto a second belt conveyor which has the same T-direction as the first belt conveyor and is preferably a horizontal belt conveyor.

38. The method according to claim 37, wherein the belt travel speed of the second belt conveyor is lower than the belt travel speed of the first belt conveyor.

39. The method according to any one of claims 28 to 30, wherein the granular molding material includes particles with an elongated shape.

40. The method according to claim 39, wherein the elongated particles have the shape of a strip, needle, spindle, or wire.

41. The method according to claim 39, wherein the elongated particle is curved along its longitudinal direction.

42. The method according to claim 39, wherein the length of the elongated particle is 20 mm or more.

43. The method according to any one of claims 28 to 30, wherein the granular molding material includes chopped carbon fiber tow prepreg.

44. The method according to claim 43, wherein the shape of the chopped carbon fiber tow prepreg is a strip.

45. The method according to claim 43, wherein the chopped carbon fiber tow prepreg is curved along the longitudinal direction.

46. The method according to claim 43, wherein the length of the chopped carbon fiber tow prepreg is 20 mm or more.

47. The method according to any one of claims 28 to 30, wherein the granular molding material includes an impregnated carbon fiber aggregate, and the impregnated carbon fiber aggregate is a carbon fiber aggregate impregnated with a thermosetting resin matrix.

48. The method according to claim 47, wherein the impregnated carbon fiber aggregate has a long, elongated shape, and the shape may be a needle, a spindle, or a wire.

49. The method according to claim 48, wherein the carbon fiber aggregate is curved along the longitudinal direction.

50. The method according to claim 48, wherein the length of the carbon fiber aggregate is 20 mm or more.

51. The method according to any one of claims 28 to 30, wherein the granular molding material includes a carbon fiber-containing fiber aggregate, and the carbon fiber-containing aggregate is a fiber aggregate containing carbon fibers, thermoplastic polymer fibers, and a binder.

52. The method according to claim 51, wherein the carbon fiber-containing fiber aggregate has an elongated shape, and the shape may be a needle, a spindle, or a wire.

53. The method according to claim 52, wherein the carbon fiber-containing fiber aggregate is curved along the longitudinal direction.

54. The method according to claim 52, wherein the length of the carbon fiber-containing fiber aggregate is 20 mm or more.

55. An apparatus for manufacturing a resin sheet containing carbon fibers, comprising: a double belt press for fusing particles contained in a granular molding material containing carbon fibers together to form a sheet; and a first belt conveyor for supplying the granular molding material to the double belt press, the conveyor belt having an uneven surface and an upward sloping section.

56. The apparatus according to claim 55, wherein the conveying surface is an uneven surface having a recess with a bottom surface and a protrusion protruding from the bottom surface, and when the uneven surface is viewed in plan, the proportion of the area occupied by the protrusion on the uneven surface is 50% or less, preferably 10% or less.

57. The apparatus according to claim 55, wherein the conveyor belt is a lattice with spikes.

58. The apparatus according to any one of claims 55 to 57, wherein the steep incline of the upward sloping section limits the amount of granular molding material that reaches the discharge end of the first belt conveyor in a unit time.

59. The apparatus according to any one of claims 55 to 57, further comprising a scraping means for scraping off a portion of the granular molding material being transported by the first belt conveyor at an intermediate or upper end of the upward sloping section.

60. The apparatus according to claim 59, wherein the scraping means includes a scraping roller, and the scraping roller has a rotation axis parallel to the T direction of the first belt conveyor, a cylindrical portion with the rotation axis as its central axis, and a plurality of blades arranged on the outer circumferential surface of the cylindrical portion, each parallel to the rotation axis.

61. The apparatus according to any one of claims 55 to 57, wherein a dispersing means that is moved in a reciprocating or circular motion for dispersing the granular molding material falling from the discharge end of the first belt conveyor is arranged below the discharge end of the first belt conveyor.

62. The apparatus according to claim 61, wherein the dispersion means includes a rod, and the rod is moved horizontally back and forth along a direction perpendicular to its longitudinal direction.