JP2020029014A - Manufacturing method for prepreg and sheet-like integrated product, and coating device - Google Patents

Abstract

To provide a manufacturing method for prepreg in which coating liquid is applied to a reinforcement fiber sheet, which can be continuously run without clogging of generated fuzz even at high running speed, and can efficiently impregnate the reinforcement fiber sheet with the coating liquid, and a coating device.SOLUTION: In a manufacturing method for prepreg 1b, a reinforcement fiber sheet 1a is passed downward in a substantially vertical direction to inside a coating part 20 storing coating liquid 2 and the coating liquid 2 is applied to the reinforcement fiber sheet 1a. The coating part 20 comprises a liquid pool part and a narrowed part communicated with each other. The liquid pool part has a part at which a cross-sectional area continuously reduces along a running direction of the reinforcement fiber sheet 1a. The narrowed part has a slit-like cross section and has a cross sectional area smaller than an upper surface of the liquid pool part. Surface roughness Rz of a surface forming a tip of the narrowed part is 0.005 μm or more and 5 μm or less.SELECTED DRAWING: Figure 1a

Description

  The present invention relates to a method and an apparatus for producing a prepreg and a sheet-like integrated body, and more particularly to a method and an apparatus for uniformly impregnating a reinforcing fiber sheet with a coating liquid.

  Fiber reinforced composite material (FRP), which is a matrix resin containing thermoplastic resin and thermosetting resin reinforced with reinforcing fibers, is a material for aviation and space, automotive material, industrial material, pressure vessel, building material, housing, medical equipment. It is used in various fields such as applications and sports. Particularly when high mechanical properties and lightness are required, carbon fiber reinforced composite materials (CFRP) are widely and suitably used. On the other hand, when cost is prioritized over mechanical properties and light weight, a glass fiber reinforced composite material (GFRP) may be used. In the FRP, a reinforcing fiber bundle is impregnated with a matrix resin to obtain an intermediate base material, which is laminated and molded, and when a thermosetting resin is used, is thermoset to produce a member made of FRP. In the above-mentioned applications, there are many planar objects and those obtained by bending the same, and the two-dimensional sheet-like material is more often used as an intermediate substrate of FRP than a one-dimensional strand or roving-like material when producing a member. It is widely used from the viewpoint of lamination efficiency and moldability.

  Recently, in order to improve the production efficiency of members made of FRP, mechanization and automation of lamination of sheet-like intermediate base materials have been promoted, and narrow tape-like intermediate base materials are preferably used here. The narrow tape-shaped intermediate substrate can be obtained by slicing a wide sheet-shaped intermediate substrate at a desired width, or by directly impregnating a narrow reinforcing fiber sheet with a matrix resin.

  As a two-dimensional sheet-like intermediate substrate, a prepreg in which a matrix resin is impregnated into a reinforcing fiber sheet is widely used. Examples of the reinforcing fiber sheet used for the prepreg include a UD base material in which reinforcing fibers are arranged in one direction and in a sheet form, and a reinforcing fiber fabric which is a woven fabric arranged in multiple directions. In particular, when the mechanical properties are prioritized, the unidirectional array reinforcing fiber bundle is often used. On the other hand, when producing an FRP having a complicated shape, a reinforcing fiber fabric having excellent shapeability and shape following properties is often used.

  Hot-melt method, one of the prepreg manufacturing methods, is to melt the matrix resin, coat it on release paper, create a laminated structure sandwiched between the upper and lower surfaces of the reinforcing fiber sheet, and apply heat and pressure. The matrix resin is impregnated inside the reinforcing fiber sheet. This method has a problem that the number of steps is large, the production speed cannot be increased, and the cost is high.

  For improving the efficiency of impregnation, for example, there has been a proposal as in Patent Document 1. In this method, a glass fiber is melt-spun and then bundled into a strand or roving to pass through a liquid reservoir having a conical flow path filled with a thermoplastic resin.

  On the other hand, a method for simultaneously forming a coating film on both sides of a sheet material is described in Patent Document 2. However, in order to prevent the fluctuation of the sheet material at the time of forming the coating film, the sheet material is passed through a web guide. After that, coating is performed with a pipe type doctor.

  As a method for producing a strip-shaped prepreg using a thermoplastic resin, a strip-type reinforcing fiber bundle is conveyed in a horizontal direction (horizontal direction), passed through a die, and a thermoplastic resin is applied to and impregnated into the strip-shaped reinforcing fiber bundle. Patent Literature 3, Patent Literature 4, etc.) are known. In Patent Document 3, a tape-like reinforcing fiber is passed through a crosshead (FIG. 2 of Patent Document 3), and a resin is applied to a tape-like reinforcing fiber bundle immediately before a linear die portion in the crosshead. Patent Document 4 discloses that a plurality of band-shaped reinforcing fiber bundles are separately introduced into a die filled with a molten thermoplastic resin, opened, impregnated, and laminated by a fixed guide (for example, a squeeze bar). It is described that the sheet-shaped prepreg is pulled out from a die.

  Further, Patent Document 5 describes that a reinforcing fiber bundle is passed through a manifold filled with a thermoplastic resin, and the die is ultrasonically vibrated by a pull-pulling method in which the reinforcing fiber bundle is pulled out from the die, thereby improving impregnation.

International Publication WO2001 / 028551 pamphlet Patent No. 3252278 JP-A-6-31821 International Publication WO2012 / 002417 Pamphlet JP-A-1-178412

  However, the method of Patent Document 1 can only produce strands or rovings, and cannot be applied to the production of sheet-shaped prepregs that are the subject of the present invention. Further, in Patent Literature 1, in order to improve the impregnation efficiency, a fluid of a thermoplastic resin is applied to the strand or the side surface of the roving-like reinforcing fiber bundle to generate turbulent flow positively in the conical flow path. It is thought that this is intended to partially disturb the arrangement of the reinforcing fiber bundles and allow the matrix resin to flow in.However, when this idea is applied to the reinforcing fiber sheet, the arrangement of the reinforcing fiber bundles is disturbed, and the quality of the prepreg is degraded. It is considered that not only does FRP decrease, but also the mechanical properties of FRP decrease.

  Further, the sheet-like material in Patent Document 2 is a film, cloth, paper, foil, a punching plate, a net-like sheet material, and the like, and the reinforcing fiber sheet which is the object of the present invention is not intended. If the technique of Patent Literature 2 is applied to a reinforcing fiber sheet made of carbon fibers, it is considered that fluff is generated by rubbing with a web guide, and the running of the reinforcing fiber sheet becomes difficult. Further, the technique of Patent Document 2 is coating of a resin, and impregnation is not intended.

  In the technique of Patent Document 3, since the tape-like reinforcing fiber passes through the slit-shaped guider chip without resin at the front portion of the die portion in the crosshead, the fluff is easily clogged, and there is no function of removing the fluff. Therefore, it is considered difficult to continuously run for a long time. In particular, it is considered that this tendency is remarkable in carbon fibers in which fluff is easily generated.

  Further, in the method of Patent Document 4, fluff is likely to stay in the liquid pool portion during continuous production, and fluff is likely to be clogged in the withdrawn portion. In particular, when the band-shaped reinforcing fiber bundle is continuously run at a high speed, the frequency of clogging of the fluff is extremely increased, so that production can be performed only at a very low speed, and there is a problem that productivity is not improved. Further, in the case of the horizontal drawing method, it is necessary to seal the die portion to prevent liquid leakage, and it is not sufficient to collect fluff during continuous production. Further, in the horizontal drawing method, when the coating liquid is impregnated inside the reinforcing fiber sheet, bubbles remaining inside the reinforcing fiber sheet are discharged in a direction orthogonal to the running direction of the reinforcing fiber sheet by buoyancy. Therefore, the discharge of air bubbles proceeds as if the impregnating coating liquid is pushed away. Therefore, there is a problem that impregnation efficiency is poor because the movement of bubbles is inhibited by the liquid and the impregnation of the coating liquid is also inhibited by the bubbles. In addition, although patent document 4 proposes exhausting air bubbles from a vent, the effect is considered to be limited only in the vicinity of the die outlet.

  Also in the technique of Patent Document 5, the reinforced fiber sheet passes through a narrow passage before the resin is applied, so that fluff is easily generated, and since it is held between the dies and brought into the die, the nap is easily clogged with the die. It is considered that the long-term running property of the fiber sheet is limited.

  Thus, a method for efficiently applying a coating liquid to a reinforcing fiber sheet such as a UD base material or a reinforcing fiber fabric and a manufacturing method have not been established yet.

  An object of the present invention is to reduce the generation of fluff in the prepreg production method, to enable continuous production without clogging, to impregnate the reinforcing fiber sheet with the coating liquid efficiently, and to increase the production speed. It is another object of the present invention to provide a prepreg manufacturing method and a coating apparatus, in which the obtained prepreg is prevented from being broken, has a uniform basis weight, and is excellent in appearance and workability.

  The method for producing a prepreg of the present invention that solves the above-mentioned problem provides a coating liquid to the reinforcing fiber sheet by passing the reinforcing fiber sheet substantially vertically downward inside the coating section where the coating liquid is stored. A method for manufacturing a prepreg, wherein the application section includes a liquid reservoir and a constricted portion that are communicated with each other, and the liquid reservoir has a portion where a cross-sectional area decreases continuously along a running direction of a reinforcing fiber sheet. The constricted portion has a slit-shaped cross section and has a cross-sectional area smaller than the upper surface of the liquid reservoir portion, and the surface forming the tip of the constricted portion has a surface roughness Rz of 0.005 μm or more and 5 μm or less. A method for producing a prepreg, which satisfies the following.

  ADVANTAGE OF THE INVENTION According to the manufacturing method of the prepreg of this invention, clogging by fluff can be suppressed and prevented greatly. Further, the reinforcing fiber sheet can be run continuously and at a high speed, and the productivity of the reinforcing fiber sheet to which the coating liquid is applied is improved.

  Further, it is possible to obtain a prepreg having a uniform basis weight and excellent appearance and workability, in which the obtained prepreg is prevented from being broken.

1 is a schematic cross-sectional view showing a prepreg manufacturing method and a coating apparatus according to an embodiment of the present invention. FIG. 1B is a schematic cross-sectional view showing a method for producing a prepreg and a coating apparatus according to another embodiment of the present invention, which is different from FIG. 1A. FIG. 2 is an enlarged detailed cross-sectional view of a coating section 20 in FIG. 1. FIG. 3 is an enlarged view of a surface forming a distal end of a stenosis portion in FIG. 2 from a cross-sectional direction. FIG. 3 is a bottom view of the application unit 20 in FIG. 2 as viewed from a direction A in FIG. 2. FIG. 3 is a cross-sectional view illustrating a structure inside the coating unit when the coating unit 20 in FIG. 2 is viewed from a direction B in FIG. 2. FIG. 6 is a cross-sectional view illustrating a flow of a coating liquid 2 in a gap 26 in FIG. 5. It is a figure showing an example of installation of a width regulation mechanism. FIG. 4 is a detailed cross-sectional view of a coating unit 20b according to another embodiment different from FIG. 2. FIG. 9 is a detailed cross-sectional view of a coating section 20c of another embodiment different from FIG. FIG. 9 is a detailed cross-sectional view of a coating unit 20d according to another embodiment different from FIG. 8. FIG. 9 is a detailed cross-sectional view of a coating unit 20e of another embodiment different from FIG. FIG. 4 is a detailed cross-sectional view of a coating unit 30 according to an embodiment different from the present invention. It is a figure showing the mode provided with the bar in the liquid pool part which is an example of an embodiment of the present invention. It is the schematic which shows the example of the prepreg manufacturing process and apparatus using this invention. It is the schematic which shows the example of the prepreg manufacturing process and apparatus using this invention. It is the schematic of an example of another prepreg manufacturing process and apparatus using this invention. It is the schematic which shows the example of the prepreg manufacturing process and apparatus using this invention. It is the schematic of an example of another prepreg manufacturing process and apparatus using this invention. It is the schematic which shows the example of the prepreg manufacturing process and apparatus using this invention. It is the schematic of an example of another prepreg manufacturing process and apparatus using this invention. It is the schematic which shows the example of the prepreg manufacturing process and apparatus using this invention. It is the schematic of an example of another prepreg manufacturing process and apparatus using this invention. It is the schematic of an example of another prepreg manufacturing process and apparatus using this invention. It is the schematic of another prepreg manufacturing process and apparatus using this invention. It is the schematic of another prepreg manufacturing process and apparatus using this invention.

  A preferred embodiment of the present invention will be described with reference to the drawings. Note that the following description exemplifies embodiments of the present invention, and the present invention is not construed as being limited thereto, and various modifications can be made without departing from the objects and effects of the present invention. .

<Outline of prepreg manufacturing method and coating apparatus>
First, an outline of a method for producing a prepreg of the present invention will be described with reference to FIG. FIG. 1a is a schematic cross-sectional view showing a prepreg manufacturing method and apparatus when a UD base material is used as a reinforcing fiber sheet according to one embodiment of the present invention. The coating apparatus 100 is provided between the transport rolls 13 and 14 as transport mechanisms 13 and 14 which are traveling mechanisms for traveling the reinforcing fiber sheet 1a substantially vertically downward Z, and a coating liquid as an application mechanism. 2 is provided with an application section 20 in which 2 is stored. In addition, before and after the coating apparatus 100, a plurality of creels 11a for unwinding the reinforcing fibers 1 and a reinforcing fiber sheet 1a in which the unwound reinforcing fibers 1 are arranged in one direction and used as a UD base (in FIG. An arrangement device 12a for obtaining an arrangement in the depth direction) and a winding device 15 for the prepreg 1b can be provided, and the coating device 100 (not shown) is provided with a coating liquid supply device. Further, if necessary, a release sheet supply device 16 for supplying the release sheet 3 can be provided. When a reinforcing fiber sheet is used as the reinforcing fiber sheet, as shown in FIG. 1B, an unwinding device 11b for unwinding the reinforcing fiber fabric and a nip roll 12b for extracting the reinforcing fiber fabric are provided in the same manner as in FIG. 1A. be able to.

<Reinforced fiber sheet>
Here, examples of the reinforcing fiber 1 include carbon fiber, glass fiber, metal fiber, metal oxide fiber, metal nitride fiber, organic fiber (aramid fiber, polybenzoxazole fiber, polyvinyl alcohol fiber, polyethylene fiber, etc.). However, it is preferable to use carbon fibers from the viewpoint of the mechanical properties and light weight of the FRP.

  Examples of the reinforcing fiber sheet used in the present invention include a UD substrate in which reinforcing fibers are arranged in one direction and a reinforcing fiber fabric as a woven fabric.

  The UD base material arranged in one direction as a reinforcing fiber sheet refers to a material in which a plurality of reinforcing fibers are arranged on a surface in one direction, and the plurality of reinforcing fibers are not necessarily integrated by being entangled with each other. You don't have to. That is, according to the production method of the present invention, after the application of the coating liquid, the coating liquid is obtained as a sheet impregnated with the coating liquid. Here, the thickness and width of the reinforcing fiber sheet are not particularly limited, and can be appropriately selected depending on the purpose and application. In the case of a carbon fiber, a fiber in which about 1,000 to about 1,000,000 single fibers are aggregated in a tape shape is called a "tow", and the tow is arranged to form a reinforcing fiber sheet. Although it can be obtained, tows may be laminated in the thickness direction. The reinforcing fiber sheet preferably has an aspect ratio defined by the width / thickness of 10 or more because it is easy to handle. In the present invention, one tape-shaped “toe” is also understood as one form of the reinforcing fiber sheet.

  The method for forming the reinforcing fiber sheet can be a known method, and is not particularly limited. A reinforcing fiber bundle in which single fibers are arranged in advance is formed, and the reinforcing fiber bundle is further arranged to form a reinforcing fiber. Forming a sheet is preferable from the viewpoints of process efficiency and uniform arrangement. For example, in carbon fiber, as described above, a `` toe '' which is a tape-shaped reinforcing fiber bundle is wound around a bobbin, and a reinforcing fiber sheet is obtained by arranging a tape-shaped reinforcing fiber bundle drawn out from this. Can be. Also, a reinforcing fiber arrangement mechanism for orderly arranging reinforcing fiber bundles drawn out from the creeled bobbin, eliminating undesirable overlapping and folding of reinforcing fiber bundles in the reinforcing fiber sheet bundle, and gaps between reinforcing fiber bundles. It is preferred to have. As the reinforcing fiber arranging mechanism, a known roller or comb-type arranging device can be used. It is also useful to stack a plurality of pre-arranged reinforcing fiber sheets from the viewpoint of reducing the gap between the reinforcing fibers. The creel is preferably provided with a tension control mechanism when drawing out the reinforcing fibers. As the tension control mechanism, a known mechanism can be used, and a brake mechanism or the like can be used. The tension can also be controlled by adjusting the thread guide.

  In addition, the reinforcing fiber fabric as the reinforcing fiber sheet of the present invention is a sheet in which reinforcing fibers are arranged in a multiaxial manner or randomly arranged. Specific examples thereof include those in which reinforcing fibers are two-dimensionally arranged in a multiaxial manner, and those in which reinforcing fibers such as a nonwoven fabric, a mat, and paper are randomly oriented, in addition to a woven fabric or a knitted fabric. In this case, the reinforcing fibers can be formed into a sheet using a method such as binder application, entanglement, welding, or fusion. As the woven fabric, a non-crimp woven fabric, a bias structure, an entangled woven fabric, a multiaxial woven fabric, a multiple woven fabric, or the like can be used in addition to the plain woven fabric, twill fabric, and satin woven fabric. The woven fabric combining the bias structure and the UD substrate not only suppresses the deformation of the woven fabric due to the tension in the coating / impregnation process due to the UD structure, but also has the pseudo-isotropy due to the bias structure, which is a preferable form. . In addition, the multi-layer fabric has an advantage that the structure / characteristics of the fabric upper / lower surface and the inside of the fabric can be individually designed. In the case of knitted fabrics, warp knitting is preferred in view of the form stability in the coating / impregnation step, but a blade which is a tubular knitted fabric can also be used.

  The thickness of the reinforcing fiber fabric is not particularly limited as long as the effects of the present invention can be obtained, and may be determined in consideration of the required FRP performance and the stability of the coating process. In consideration of the permeability of the stenosis, it is preferably 1 mm or less, more preferably 0.3 mm or less.

  A reinforcing fiber fabric suitable for the purpose can be obtained and manufactured from the market, and an example thereof will be described below. Examples of the fabric include, for example, C06142, C06347B, and C05642 of “Treca” cloth manufactured by Toray Industries, Inc., “HexForce” Fabrics manufactured by HEXCEL and 84, G0801, XAGP282P, 43195, G0939, G0803, 43936PXXG of “PrimeTex”. , SGP203CS, XC1400, 48200, 48287, 46150, "Injetex" Fabrics GB201, G0986, G0926, etc., and G1088, G0874, G0973, 43743, etc., which are hybrid fabrics of carbon fiber and glass fiber, and 20796, 21263, which are aramid fiber fabrics And Quartz fabrics 610, 593, and the like. Examples of the nonwoven fabric, mat, and paper include “Torayca” mats B030, B050, and BV03 manufactured by Toray Industries, Inc., and CEO-030, CBP-030, and ZX-020 manufactured by Olivet “Carbolite”.

<Smoothing of reinforcing fiber sheet>
In the present invention, by increasing the surface smoothness of the reinforcing fiber sheet, it is possible to improve the uniformity of the application amount in the application section. For this reason, it is preferable to guide the reinforcing fiber sheet to the liquid pool after performing the smoothing treatment. The method of smoothing is not particularly limited, and examples thereof include a method of physically pressing with a facing roll or the like, and a method of moving a reinforcing fiber using an air flow. The physical pressing method is preferred because it is simple and does not easily disturb the arrangement of the reinforcing fibers. More specifically, calendering or the like can be used. The method using an air flow is preferable because it not only causes less abrasion but also has the effect of widening the reinforcing fiber sheet.

<Widening of reinforced fiber sheet>
In the present invention, it is also preferable to guide the reinforcing fiber sheet to the liquid pool after widening the reinforcing fiber sheet from the viewpoint of efficiently producing a thin prepreg. There is no particular limitation on the widening method, and examples thereof include a method of mechanically applying vibration and a method of expanding the reinforcing fibers by an air flow. As a method of mechanically applying vibration, there is a method of bringing a reinforcing fiber sheet into contact with a vibrating roll as described in, for example, JP-A-2015-22799. As the vibration direction, when the traveling direction of the reinforcing fiber sheet is the X axis, it is preferable to apply vibrations in the Y axis direction (horizontal direction) and the Z axis direction (vertical direction). It is also preferable to use them in combination. It is preferable that a plurality of projections are provided on the surface of the vibrating roll, because the abrasion of the reinforcing fibers by the roll can be suppressed. As a method using an air flow, for example, SEN-IGAKKAISHI, vol. 64, P-262-267 (2008). The described method can be used.

<Preheating of reinforced fiber sheet>
In addition, in the present invention, it is preferable that the reinforcing fiber sheet is heated and then guided to the liquid pool portion, because the temperature decrease of the coating liquid can be suppressed and the viscosity uniformity of the coating liquid can be improved. The reinforcing fiber sheet is preferably heated to a temperature close to the temperature of the coating solution, and various heating means for this purpose include air heating, infrared heating, far infrared heating, laser heating, contact heating, and heating medium heating (such as steam). Means can be used. Above all, infrared heating is preferable because the apparatus is simple and the reinforcing fiber sheet can be directly heated, so that it can be efficiently heated to a desired temperature even at a high running speed.

<Coating liquid>
The coating liquid used in the present invention can be appropriately selected according to the purpose of application. For example, when applied to the production of a sheet-shaped prepreg, a coating liquid of a matrix resin can be used. The prepreg coated with the matrix resin obtained by the present invention is in a state where the matrix resin is impregnated in the reinforcing fiber sheet, and can be laminated and molded as it is as a sheet-shaped prepreg to obtain a member made of FRP. The degree of impregnation can be controlled by the design of the application section and the additional impregnation after application. The matrix resin can be appropriately selected depending on the application, but it is common to use a thermoplastic resin or a thermosetting resin. The matrix resin may be a molten resin heated and melted or a coating liquid at room temperature. Further, a solution or a varnish formed using a solvent may be used.

  As the matrix resin, those generally used for FRP, such as a thermoplastic resin, a thermosetting resin, and a photocurable resin, can be used. Further, these may be used as they are if they are liquids at room temperature, or may be used as solids or viscous liquids at room temperature to reduce the viscosity by heating, or may be used as a melt by melting, or a solvent. May be used as a solution or varnish.

  The thermoplastic resin is selected from a carbon-carbon bond, an amide bond, an imide bond, an ester bond, an ether bond, a carbonate bond, a urethane bond, a urea bond, a thioether bond, a sulfone bond, an imidazole bond, and a carbonyl bond in the main chain. A polymer having a bond can be used. Specifically, polyacrylate, polyolefin, polyamide (PA), aramid, polyester, polycarbonate (PC), polyphenylene sulfide (PPS), polybenzimidazole (PBI), polyimide (PI), polyetherimide (PEI), polysulfone (PSU), polyether sulfone (PES), polyether ketone (PEK), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyaryl ether ketone (PAEK), polyamide imide (PAI), etc. it can. In fields requiring heat resistance such as aircraft applications, PPS, PES, PI, PEI, PSU, PEEK, PEKK, PAEK, and the like are suitable. On the other hand, for industrial applications and automotive applications, polyolefins such as polypropylene (PP), PA, polyester, PPS, and the like are preferable in order to increase molding efficiency. These may be polymers or oligomers or monomers for low viscosity and low temperature coating. Of course, these may be copolymerized depending on the purpose, or may be used as a polymer blend alloy by mixing various types.

  Examples of the thermosetting resin include an epoxy resin, a maleimide resin, a polyimide resin, a resin having an acetylene terminal, a resin having a vinyl terminal, a resin having an allyl terminal, a resin having a nadic acid terminal, and a resin having a cyanate ester terminal. Can be These can be generally used in combination with a curing agent or a curing catalyst. In addition, these thermosetting resins can be appropriately used in combination.

  As a thermosetting resin suitable for the present invention, an epoxy resin is preferably used because of its excellent heat resistance, chemical resistance, and mechanical properties. In particular, an epoxy resin using an amine, a phenol, or a compound having a carbon-carbon double bond as a precursor is preferable. Specifically, various isomers of tetraglycidyldiaminodiphenylmethane, triglycidyl-p-aminophenol, triglycidyl-m-aminophenol, and triglycidylaminocresol, and phenols are used as epoxy resins having amines as precursors. Bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, a compound having a carbon-carbon double bond as a precursor Examples of the epoxy resin include, but are not limited to, alicyclic epoxy resins. Brominated epoxy resins obtained by brominating these epoxy resins are also used. An epoxy resin having an aromatic amine represented by tetraglycidyldiaminodiphenylmethane as a precursor has a good heat resistance and a good adhesion to a reinforcing fiber, and is most suitable for the present invention.

  A thermosetting resin is preferably used in combination with a curing agent. For example, in the case of an epoxy resin, the curing agent may be a compound having an active group capable of reacting with an epoxy group. Preferably, a compound having an amino group, an acid anhydride group, or an azide group is suitable. Specifically, dicyandiamide, various isomers of diaminodiphenylsulfone, and aminobenzoic acid esters are suitable. More specifically, dicyandiamide is preferably used because of its excellent prepreg preservability. Further, various isomers of diaminodiphenyl sulfone are most suitable for the present invention because they give cured products having good heat resistance. As the aminobenzoic acid esters, trimethylene glycol di-p-aminobenzoate and neopentyl glycol di-p-aminobenzoate are preferably used. Compared with diaminodiphenyl sulfone, the heat resistance is lower, but the tensile strength is lower. Because it is excellent, it is selected and used according to the application. It is also possible to use a curing catalyst if necessary. From the viewpoint of improving the pot life of the coating liquid, it is also possible to use a complexing agent capable of forming a complex with a curing agent or a curing catalyst.

  In the present invention, it is also preferable to use a thermoplastic resin mixed with a thermosetting resin. A mixture of a thermosetting resin and a thermoplastic resin gives better results than using the thermosetting resin alone. This is because while thermosetting resins generally have the disadvantage of being brittle, low-pressure molding with an autoclave is possible, whereas thermoplastic resins have the advantage of being generally tough, but low-pressure molding with an autoclave is difficult. This is because they exhibit a trade-off characteristic, that is, they can be used in combination to balance physical properties and moldability. When mixed and used, it is preferable to contain the thermosetting resin in an amount of more than 50% by mass from the viewpoint of the mechanical properties of the FRP obtained by curing the prepreg.

<Polymer particles>
In the present invention, it is preferable to use a coating liquid containing polymer particles because the toughness and impact resistance of the obtained CFRP can be improved. At this time, it is preferable that the glass transition temperature (Tg) or the melting point (Tm) of the polymer particles is higher than the coating liquid temperature by 20 ° C. or more, because the shape of the polymer particles can be easily maintained in the coating liquid. The Tg of the polymer particles can be measured using a temperature-modulated DSC under the following conditions. As the temperature modulation DSC device, Q1000 manufactured by TA Instruments or the like is suitable, and it can be used after being calibrated with high-purity indium in a nitrogen atmosphere. The measurement conditions are as follows: the temperature rise rate is 2 ° C./min, and the temperature modulation condition is a cycle of 60 seconds and an amplitude of 1 ° C. The reversible component is separated from the total heat flow obtained in this way, and the temperature at the middle point of the step signal can be set to Tg.

  In addition, Tm is measured by a normal DSC at a heating rate of 10 ° C./min, and the peak top temperature of a peak signal corresponding to melting can be defined as Tm.

  Further, the polymer particles are preferably insoluble in the coating liquid. As such polymer particles, for example, appropriate ones can be used by referring to the description in WO2009 / 142231 pamphlet and the like. More specifically, polyamide or polyimide can be preferably used, and polyamide, which can greatly improve impact resistance due to excellent toughness, is most preferable. As the polyamide, semi-IPN (polymer interpenetrating network structure) using polyamide 12, polyamide 11, polyamide 6, polyamide 66 or polyamide 6/12 copolymer, or the epoxy compound described in Example 1 of JP-A-01-104624. Polyamide (semi-IPN polyamide) or the like can be suitably used. The shape of the thermoplastic resin particles may be a spherical particle, a non-spherical particle, or a porous particle, but a spherical shape is particularly preferable in the production method of the present invention since the flow characteristics of the resin are not deteriorated. Further, a spherical shape is a preferable embodiment in that there is no starting point of stress concentration and high impact resistance is given.

  Commercially available polyamide particles include SP-500, SP-10, TR-1, TR-2, 842P-48, 842P-80 (all manufactured by Toray Industries, Inc.) and "Orgasol (registered trademark)" 1002D. , 2001UD, 2001EXD, 2002D, 3202D, 3501D, 3502D (all manufactured by Arkema Co., Ltd.), "Grillamide (registered trademark)" TR90 (manufactured by Mazaverke Co., Ltd.), "TROGAMID (registered trademark)" CX7323, CX9701 , CX9704 (manufactured by Degussa Co., Ltd.) and the like can be used. These polyamide particles may be used alone or in combination of two or more.

  Further, in order to increase the toughness of the CFRP interlayer resin layer, it is preferable to keep the polymer particles in the interlayer resin layer. Therefore, the number average particle size of the polymer particles is preferably in the range of 5 to 50 μm, more preferably in the range of 7 to 40 μm, and still more preferably in the range of 10 to 30 μm. By setting the number average particle diameter to 5 μm or more, the particles do not enter the bundle of the reinforcing fibers and can stay in the interlayer resin layer of the obtained fiber-reinforced composite material. By setting the number average particle size to 50 μm or less, the thickness of the matrix resin layer on the prepreg surface can be optimized, and thus, in the obtained CFRP, the fiber mass content can be optimized.

<Coating liquid viscosity>
As the coating liquid used in the present invention, it is preferable to select an optimum viscosity from the viewpoint of processability and stability. Specifically, when the viscosity is in the range of 1 to 60 Pa · s, it is possible to suppress the liquid dripping at the outlet of the constriction portion and to improve the high-speed running property and the stable running property of the reinforcing fiber sheet, which is preferable. Here, the viscosity refers to a value measured at a coating liquid temperature in a liquid pool at a strain rate of 3.14 s ^-1 . As the measuring device, a viscoelasticity measuring device such as a parallel disk type or a cone type can be used. The viscosity of the coating liquid is more preferably from 10 to 30 Pa · s.

<Coating process>
The case where a UD base material is used as the reinforcing fiber sheet will be described with reference to FIG. 1A. The method of applying the coating liquid 2 to the reinforcing fiber sheet 1a in the coating apparatus 100 is based on a method in which a plurality of the creels 11 are unwound. After arranging the reinforcing fibers 1 in one direction (in the depth direction of the paper) by the arrangement device 12a to obtain a reinforcing fiber sheet 1a as a UD base material, the reinforcing fiber sheet 1a is applied to the application section 20 in a substantially vertically downward Z direction. To apply the coating liquid 2 to both sides of the sheet-like reinforcing fiber sheet 1a. Thereby, the prepreg 1b can be obtained. In the case where a reinforcing fiber fabric is used, the creel 11 shown in FIG.

  Further, if necessary, the release sheet 3 may be provided on at least one side of the prepreg 1b, and the prepreg 1b and the release sheet 3 may be simultaneously wound by the winding device 15. In particular, even when the coating liquid 2 applied to the prepreg 1b reaches the transport roll 14, a part or all of the coating liquid 2 is present on the surface of the prepreg 1b, and when the fluidity or the adhesiveness is high, the release sheet is used. 3 prevents a part of the coating liquid 2 on the prepreg 1b from being transferred to the transport roll 14. Further, the adhesion between the prepregs 1b can be prevented, and the handling in the subsequent process becomes easy. The release sheet is not particularly limited as long as it has the above-mentioned effect, and examples thereof include release paper, and those obtained by applying a release agent to the surface of an organic polymer film.

  Next, the step of applying the coating liquid 2 to the reinforcing fiber sheet 1a will be described in detail with reference to FIGS. FIG. 2 is an enlarged detailed cross-sectional view of the application unit 20 in FIG. The coating unit 20 includes wall members 21a and 21b facing each other with a predetermined gap D therebetween, and a cross-sectional area between the wall members 21a and 21b is continuous in a vertically downward Z (that is, a running direction of the reinforcing fiber sheet). The liquid reservoir 22 which is gradually reduced, is located below the liquid reservoir 22 (the side where the reinforcing fiber sheet 1a is carried out), and is smaller than the cross-sectional area of the upper surface of the liquid reservoir 22 (the side where the reinforcing fiber sheet 1a is introduced). A slit-shaped constriction 23 having a cross-sectional area is formed. In FIG. 2, the reinforcing fiber sheets 1a are arranged in the depth direction of the paper surface.

  In the application section 20, the reinforcing fiber sheet 1a introduced into the liquid pool section 22 travels in the vertical downward Z while accompanying the surrounding coating liquid 2. At that time, since the cross-sectional area of the liquid reservoir 22 decreases in the vertical downward direction Z (the running direction of the reinforcing fiber sheet 1a), the accompanying coating liquid 2 is gradually compressed and moves toward the lower part of the liquid reservoir 22. As the pressure increases, the pressure of the coating liquid 2 increases. When the pressure in the lower part of the liquid reservoir 22 becomes higher, the accompanying liquid flow becomes more difficult to flow further downward, flows in the direction of the wall members 21a and 21b, and is then blocked by the wall members 21a and 21b and flows upward. Become like As a result, a circulating flow T is formed in the liquid reservoir 22 along the flat surface of the reinforcing fiber sheet 1a and the wall surfaces of the wall members 21a and 21b. Thereby, even if the reinforcing fiber sheet 1a brings the fluff into the liquid reservoir 22, the fluff moves along the circulating flow T and cannot approach the lower part of the liquid reservoir 22 or the narrowed portion 23 where the hydraulic pressure is large. As described further below, the air bubbles adhere to the fluff, and the fluff moves upward from the circulating flow T and passes near the upper liquid level of the liquid reservoir 22. Therefore, not only is it possible to prevent the fluff from clogging the lower portion of the liquid reservoir 22 and the narrowed portion 23, but also it is possible to easily collect the retained fluff from the upper liquid surface of the liquid reservoir 22. Furthermore, when the reinforcing fiber sheet 1a is run at a high speed, the above-mentioned liquid pressure is further increased, so that the effect of eliminating fluff becomes higher. As a result, it becomes possible to apply the coating liquid 2 at high speed to the reinforcing fiber sheet 1a, and productivity is greatly improved.

  Further, there is an effect that the coating liquid 2 is easily impregnated into the inside of the reinforcing fiber sheet 1a by the increased liquid pressure. This is based on the property (Darcy's law) that when a coating liquid is impregnated into a porous body such as a UD substrate or a reinforcing fiber fabric, the degree of impregnation increases with the pressure of the coating liquid. Also in this case, when the reinforcing fiber sheet 1a is run at a higher speed, the hydraulic pressure is further increased, so that the impregnation effect can be further enhanced. The coating liquid 2 is impregnated with the air bubbles remaining inside the reinforcing fiber sheet 1a by gas / liquid replacement. It is discharged in the orientation direction (vertically upward). At this time, since the air bubbles are discharged without displacing the impregnated coating liquid 2, there is also an effect of not impairing the impregnation. Some of the air bubbles are discharged out of the surface of the reinforcing fiber sheet 1a in the out-of-plane direction (normal direction). However, the air bubbles are also quickly eliminated vertically upward by the above-mentioned liquid pressure and buoyancy. There is also an effect that the discharge of air bubbles proceeds efficiently without staying at the lower part of the liquid reservoir 22 having a high effect. By these effects, it is possible to impregnate the reinforcing fiber sheet 1a with the coating liquid 2 efficiently, and as a result, it is possible to obtain a high-quality prepreg 1b in which the coating liquid 2 is uniformly impregnated.

  Further, the reinforcing fiber sheet 1a is automatically centered at the center of the gap D by the increased liquid pressure, and the reinforcing fiber sheet 1a does not directly rub against the wall surface of the liquid reservoir 22 or the narrowed portion 23. It also has the effect of suppressing the generation of fluff. This is because when the reinforcing fiber sheet 1a approaches one of the gaps D due to disturbance or the like, the coating liquid 2 is pushed into the narrower gap on the approaching side and compressed, so that the hydraulic pressure increases on the approaching side. Then, the reinforcing fiber sheet 1a is pushed back to the center of the gap D.

  The constricted portion 23 is designed to have a smaller sectional area than the upper surface of the liquid reservoir 22. As can be understood from FIG. 2, the length of the pseudo plane due to the reinforcing fiber sheet bundle in the perpendicular direction is small, that is, the interval between the members is small, so that the cross-sectional area is small. This is because the impregnation and the self-centering effect can be obtained by increasing the fluid pressure at the constricted portion as described above. The cross-sectional shape of the uppermost surface of the constricted portion 23 should be made to match the cross-sectional shape of the lowermost surface of the liquid reservoir 22, from the viewpoint of the running property of the reinforcing fiber sheet 1a and the flow control of the coating liquid 2. Although preferred, the constriction 23 may be slightly larger if necessary.

  Here, in the application section 20 of FIG. 2, the reinforcing fiber sheet 1a runs completely downward in the vertical direction Z (90 degrees from the horizontal plane), but the present invention is not limited to this. Is obtained, and the reinforcing fiber sheet 1a may be directed substantially vertically downward within a range in which the fiber sheet 1a can be stably and continuously driven.

  Further, the total amount of the coating liquid 2 applied to the reinforcing fiber sheet 1a can be controlled by the gap D of the narrowed portion 23. For example, it is desired to increase the total amount of the coating liquid 2 applied to the reinforcing fiber sheet 1a (to increase the basis weight). In this case, the wall members 21a and 21b may be installed so that the gap D is widened.

  FIG. 3 shows an enlarged view of the distal end 50 of the stenosis part in FIG. The distal end of the constricted portion has a constricted surface 51 and an open-to-atmosphere surface 52 that is open to the atmosphere adjacent to the constricted surface, and is formed by corners 53 formed by the respective surfaces. The surface forming the distal end of the constricted portion refers to the constricted surface 51 and the open-to-atmosphere surface 52. In the application section of the present invention, it is necessary that the surface forming the front end of the constriction has a surface roughness Rz (surface height roughness) of 0.005 μm or more and 5 μm or less. From the viewpoint of wall member processing, it is preferable that the entire surface of the constricted surface 51 and the open-to-atmosphere surface 52 satisfy the above range of the surface roughness Rz. Even when only the surface roughness Rz satisfies the above range, the effects of the present invention can be exhibited. U in FIG. 3 is a coating liquid flow U near the corresponding position. The coating liquid flow U flows along the corner formed by the constriction surface 51 and the open-to-atmosphere surface 52, and then separates from the wall member. If the surface roughness Rz of the surface forming the distal end of the constricted portion is not 0.005 μm or more, the releasability of the coating liquid flow U from the wall member is deteriorated, the amount of the coating liquid applied becomes unstable, and the basis weight is reduced. Vary. If the releasability of the coating liquid flow U is poor, the coating liquid solidifies in the vicinity of the corner formed by the constriction surface and the open air surface, and the coating liquid becomes streaky on the prepreg. It causes poor appearance such as defects due to detachment of the applied coating liquid from the wall surface. In addition, the streak of the coating liquid on the prepreg is a variation in the thickness of the coating liquid in the width direction of the prepreg. . Preferably, the surface forming the tip of the constriction has a surface roughness Rz of 0.1 μm or more. on the other hand. It is necessary that the surface forming the tip of the constriction has a surface roughness Rz of 5 μm or less. If the surface roughness Rz is greater than 5 μm, the unevenness of the stenotic surface is transferred to the coating liquid and becomes streak-like, the appearance is poor, the weight per unit area is reduced, and the friction between the coating liquid and the wall surface is reduced. The liquid drips and causes variations in the basis weight. More preferably, the surface forming the tip of the constriction has a surface roughness Rz of 1 μm or less.

  FIG. 4 is a bottom view of the application unit 20 as viewed from the direction of A in FIG. The coating section 20 is provided with side wall members 24a and 24b for preventing the coating liquid 2 from leaking from both ends in the arrangement direction of the reinforcing fiber sheet 1a, and is surrounded by the wall members 21a and 21b and the side wall members 24a and 24b. The outlet 26 of the constricted portion 23 is formed in the closed space. Here, the outlet 26 has a slit shape, and the sectional aspect ratio (Y / D in FIG. 4) may be set according to the shape of the reinforcing fiber sheet 1a to which the coating liquid 2 is to be applied.

  FIG. 5 is a cross-sectional view illustrating the structure inside the application section when the application section 20 is viewed from the direction B. Note that the wall member 21b is omitted for easy viewing of the drawing.

  FIG. 6 shows the flow of the coating liquid 2 in the gap 26. If the gap 26 is large, a vortex flows in the coating liquid 2 in the direction of R. Since the vortex flow R becomes a flow (Ra) directed outward at a lower portion of the liquid pool 22, there is a possibility that the reinforcing fiber sheet is torn (fibers are broken). On the other hand, in the upper part of the liquid reservoir 22, since the flow becomes inward (Rb), the reinforcing fiber sheet 1a is compressed in the width direction, and the end may be broken. In an apparatus represented by Patent Document 2 (Japanese Patent No. 3252278) for applying a coating liquid to both surfaces of a monolithic substrate (especially, a film), even if such a vortex occurs in the gap 26, the quality is high. Attention was not paid to the impact on the environment.

Therefore, in the present invention, it is preferable to restrict the width of the gap 26 so as to suppress the generation of the vortex at the end. Specifically, the width L of the liquid reservoir 22, that is, the interval L between the side plate members 24a and 24b may be configured to satisfy the following relationship with the width W of the reinforcing fiber sheet measured immediately below the narrowed portion 23. preferable.
L ≦ W + 10 (mm).

  Thereby, the generation of vortex flow at the end is suppressed, the cracking of the reinforcing fiber sheet 1a and the breaking of the end can be suppressed, and the reinforcing fibers 1 are uniformly arranged over the entire width (W) of the prepreg 1b, and high quality and stable. A highly reliable prepreg 1b can be obtained. Furthermore, when this technology is applied to a prepreg, not only can the quality and quality of the prepreg be improved, but also the mechanical properties and quality of the FRP obtained using the prepreg can be improved. More preferably, when the relationship between L and W is L ≦ W + 2 (mm), cracks and end breaks in the reinforcing fiber sheet can be further suppressed.

  Further, it is preferable to adjust the lower limit of L to be not less than W-5 (mm) from the viewpoint of improving the uniformity of the dimension in the width direction of the prepreg 1b.

  Note that this width regulation is preferably performed at least at the lower part of the liquid reservoir 22 (the position G in FIG. 5) from the viewpoint of suppressing the generation of the vortex R due to the high liquid pressure below the liquid reservoir 22. Further, more preferably, when this width regulation is performed in the entire area of the liquid pool 22, the generation of the vortex flow R can be almost completely suppressed, and as a result, cracks and end breaks of the reinforcing fiber sheet can be almost completely prevented. Can be suppressed.

  In addition, from the viewpoint of suppressing the vortex flow in the gap 26, the width regulation may be performed only on the liquid pool portion 22, but when the constriction portion 23 is similarly performed, the excess coating liquid 2 is applied to the side surface of the prepreg 1b. It is preferable from the viewpoint of suppressing this.

<Width regulation mechanism>
In the above, the case where the side wall members 24a and 24b play the width regulation has been described. However, as shown in FIG. 7, width regulation mechanisms 27a and 27b may be provided between the side wall members 24a and 24b, and the width regulation may be performed by such a mechanism. it can. This is preferable from the viewpoint that prepregs having various widths can be manufactured by one coating portion by allowing the width regulated by the width regulating mechanism to be freely changed. Here, the relationship between the width (W) of the reinforcing fiber sheet immediately below the constriction and the width (L2) regulated by the width regulating mechanism at the lower end of the width regulating mechanism is preferably L2 ≦ W + 10 (mm), More preferably, L2 ≦ W + 2 (mm). Further, it is preferable to adjust the lower limit of L2 to be equal to or more than W-5 (mm) from the viewpoint of improving the uniformity of the dimension in the width direction of the prepreg 1b. There is no particular limitation on the shape and material of the width regulating mechanism, but a plate-shaped bush is simple and preferable. In the upper part, that is, in a place close to the liquid surface, the width is smaller than the distance between the wall members 21a and 21b (refer to FIG. 7, which indicates the length in the vertical direction of the width regulating mechanism in the "view from the Z direction"). By having this, the flow of the coating liquid in the horizontal direction can be prevented, which is preferable. On the other hand, from the middle part to the lower part of the width regulating mechanism, it is preferable that the shape conforms to the internal shape of the application part, because the retention of the coating liquid in the liquid pool part can be suppressed and the deterioration of the coating liquid can be suppressed. In this sense, it is preferable that the width regulating mechanism is inserted up to the constriction 23. FIG. 7 shows an example of a plate-shaped bush as the width regulating mechanism, but shows an example in which the lower part from the middle of the bush follows the tapered shape of the liquid reservoir 22 and is inserted to the constriction 23. FIG. 7 shows an example in which L2 is constant from the liquid surface to the outlet, but the width regulated by the portion may be changed within a range that achieves the purpose of the width regulating mechanism. The width regulating mechanism can be fixed to the application section 20 by an arbitrary method. In the case of a plate-shaped bush, by fixing the plate-shaped bush at a plurality of portions in the up-down direction, regulation by deformation of the plate-shaped bush due to high hydraulic pressure. Variation in width can be suppressed. For example, it is preferable to use a stay for the upper portion and to insert the lower portion into the application portion, since the width can be easily regulated by the width regulating mechanism.

<Shape of liquid pool>
As described in detail above, in the present invention, the liquid pressure is increased in the running direction of the reinforcing fiber sheet by continuously decreasing the cross-sectional area in the running direction of the reinforcing fiber sheet in the liquid reservoir 22. It is important to note that the continuous decrease in the cross-sectional area in the running direction of the reinforcing fiber sheet is not particularly limited as long as the hydraulic pressure can be continuously increased in the running direction. In the cross-sectional view of the liquid reservoir, the liquid reservoir may have a curved shape such as a tapered shape (linear shape) or a trumpet shape. In addition, the cross-sectional area decreasing portion may be continuous over the entire length of the liquid pool portion, or may include a portion where the cross-sectional area does not decrease or a portion which expands conversely as long as the object and effects of the present invention can be obtained. You may go out. These will be described in detail below with reference to FIGS.

  FIG. 8 is a detailed cross-sectional view of the application section 20b of another embodiment different from FIG. It is the same as the coating unit 20 of FIG. 2 except that the shapes of the wall members 21c and 21d constituting the liquid pool 22 are different. As in the application section 20b in FIG. 8, the liquid reservoir 22 may be divided into a region 22a in which the cross-sectional area continuously decreases in the vertical direction Z downward and a region 22b in which the cross-sectional area does not decrease. At this time, the vertical height H at which the cross-sectional area is continuously reduced is preferably 10 mm or more. The vertical height H at which the more preferable cross-sectional area is continuously reduced is 50 mm or more. As a result, the distance in which the coating liquid 2 entrained by the reinforcing fiber sheet 1a is compressed in the region 22a where the cross-sectional area of the liquid pool 22 is continuously reduced is secured, and the liquid generated in the lower part of the liquid pool 22 is secured. The pressure can be increased sufficiently. As a result, it is possible to prevent the fluff from clogging the constricted portion 23 due to the hydraulic pressure, and to obtain the effect of impregnating the reinforcing fiber sheet 1a with the coating liquid 2 by the hydraulic pressure.

  Here, when the region 22a where the cross-sectional area of the liquid reservoir 22 is continuously reduced is tapered like the coating portion 20 in FIG. 2 or the coating portion 20b in FIG. 8, the opening angle θ of the taper is smaller. More specifically, it is preferable to form an acute angle (90 ° or less). Thereby, the compression effect of the coating liquid 2 can be enhanced in the region 22a (tapered portion) where the cross-sectional area of the liquid reservoir 22 is continuously reduced, and a high liquid pressure can be easily obtained.

  FIG. 9 is a detailed cross-sectional view of the application section 20c of another embodiment different from FIG. 8 is the same as the application section 20b in FIG. 8 except that the wall members 21e and 21f forming the liquid pool section 22 have a two-step tapered shape. As described above, the region 22a where the cross-sectional area of the liquid reservoir 22 is continuously reduced may be configured by a multi-stage taper portion of two or more stages. At this time, it is preferable to make the opening angle θ of the tapered portion closest to the constricted portion 23 an acute angle from the viewpoint of enhancing the compression effect. Also in this case, it is preferable that the height H of the region 22a where the cross-sectional area of the liquid reservoir 22 is continuously reduced is 10 mm or more. The vertical height H at which the more preferable cross-sectional area is continuously reduced is 50 mm or more. As shown in FIG. 9, the area 22 a where the cross-sectional area of the liquid reservoir 22 is continuously reduced is formed as a multi-stage tapered portion, so that the volume of the coating liquid 2 that can be stored in the liquid reservoir 22 is maintained while the constricted portion 23 is maintained. Can be further reduced. As a result, the liquid pressure generated in the lower part of the liquid reservoir 22 is further increased, and the effect of removing fluff and the effect of impregnating the coating liquid 2 can be further enhanced.

  FIG. 10 is a detailed cross-sectional view of a coating unit 20d according to another embodiment different from FIG. It is the same as the application part 20b of FIG. 8 except that the shape of the wall members 21g and 21h constituting the liquid pool part 22 is stepped. As described above, if there is a region 22a in which the cross-sectional area is continuously reduced at the lowermost portion of the liquid reservoir 22, the effect of increasing the hydraulic pressure, which is the object of the present invention, can be obtained. May include a region 22c in which the cross-sectional area decreases intermittently. By forming the liquid reservoir 22 in a shape as shown in FIG. 10, the depth B of the liquid reservoir 22 can be stored while expanding the depth B of the liquid reservoir 22 while maintaining the shape of the region 22 a where the cross-sectional area is continuously reduced. The volume can be increased. As a result, even when the coating liquid 2 cannot be continuously supplied to the coating section 20d, the coating liquid 2 can be continuously applied to the reinforcing fiber sheet 1a for a long time, and the productivity of the prepreg 1b is further improved.

  FIG. 11 is a detailed cross-sectional view of a coating unit 20e according to another embodiment different from FIG. It is the same as the application section 20b of FIG. 8 except that the shape of the wall members 21i and 21j forming the liquid pool section 22 is a trumpet shape (curved shape). In the application section 20b of FIG. 8, the area 22a where the cross-sectional area of the liquid pool section 22 is continuously reduced is tapered (linear), but is not limited to this. For example, as shown in FIG. May be. However, it is preferable that the lower part of the liquid pool part 22 and the upper part of the narrow part 23 are connected smoothly. This is because if there is a step at the boundary between the lower part of the liquid pool part 22 and the upper part of the narrow part 23, the reinforcing fiber sheet 1a is caught by the step, and there is a concern that fluff is generated at this part. When the region where the cross-sectional area of the liquid reservoir 22 is continuously reduced is a trumpet-like shape, the opening of the virtual tangent line at the lowermost part of the region 22a where the cross-sectional area of the liquid reservoir 22 is continuously reduced. It is preferable that the angle θ be an acute angle.

  In the above description, an example in which the cross-sectional area is smoothly reduced has been described. However, in the present invention, the cross-sectional area of the liquid reservoir does not necessarily have to be smoothly reduced unless the object of the present invention is impaired.

  FIG. 12 is a detailed cross-sectional view of a coating unit 30 according to another embodiment different from the present invention. Unlike the embodiment of the present invention, the liquid reservoir 32 in FIG. 12 does not include a region in which the cross-sectional area continuously decreases in the vertical direction Z, and the cross-sectional area is discontinuous and sharp at the boundary 33 with the constriction 23. It is a structure which reduces to. Therefore, the reinforcing fiber sheet 1a is easily clogged.

  In addition, it is also possible to improve the impregnation effect by bringing the reinforcing fiber sheet into contact with a plurality of bars in the application section. FIG. 13 shows an example in which three bars (35a, 35b, and 35c) are used. The greater the number of bars, the longer the contact length between the reinforcing fiber sheet and the bars, the larger the contact angle, the greater the impregnation ratio. Can be improved. In the example of FIG. 13, the impregnation rate can be set to 90% or more. The means for improving the impregnation effect may be used in combination of plural kinds.

<Travel mechanism>
As a traveling mechanism for transporting the reinforcing fiber sheet or the prepreg of the present invention, a known roller or the like can be suitably used. In the present invention, since the reinforcing fiber sheet is conveyed vertically downward, it is preferable to arrange rollers vertically above and below the application section.

  In the present invention, it is preferable that the running path of the reinforcing fiber sheet is as linear as possible in order to suppress the arrangement disorder and the fluffing of the reinforcing fibers. In addition, in the process of transporting the sheet-like integrated material, which is a laminate of the prepreg and the release sheet, if there is a bent portion, wrinkles may occur due to a difference in circumference between the inner layer and the outer layer. It is also preferable that the path is as straight as possible. From this viewpoint, it is preferable to use a nip roll in the traveling path of the sheet-like integrated object.

  Whether to use the S-shaped roll or the nip roll can be appropriately selected according to the manufacturing conditions and the characteristics of the product.

<High tension take-up device>
In the present invention, it is preferable to arrange a high tension take-up device for drawing out the prepreg from the application section downstream of the application section. This is because high frictional force and shear stress are generated between the reinforcing fiber sheet and the coating liquid in the application section, and it is preferable to generate a high take-up tension downstream of the process in order to overcome the drawback and draw out the prepreg. It is. As the high tension take-up device, a nip roll or an S-shaped roll can be used, but by increasing the frictional force between the roll and the prepreg, slip can be prevented and stable running can be achieved. . For this purpose, it is preferable to arrange a material having a high coefficient of friction on the roll surface or to increase the nip pressure or the pressing pressure of the prepreg against the S-shaped roll. From the viewpoint of preventing the slip, the S-shaped roll is preferable because the frictional force can be easily controlled by the roll diameter and the contact length.

<Release sheet feeding device, winder>
In the production of a prepreg or FRP using the present invention, a release sheet feeding device or a winder can be used as appropriate, and as such a device, a known device can be used. It is preferable to provide a mechanism capable of feeding back the winding tension or feeding back the winding speed from the viewpoint of stable running of the sheet.

<Addition impregnation>
In order to adjust the degree of impregnation to a desired degree, it is also possible to combine a means for further increasing the degree of impregnation using an impregnating apparatus separately after coating with the present invention. Here, in order to distinguish it from the impregnation in the application section, additional impregnation after application is referred to as additional impregnation, and an apparatus therefor is referred to as an additional impregnation apparatus. The device used as the additional impregnation device is not particularly limited, and can be appropriately selected from known devices according to the purpose. For example, as described in JP-A-2011-132389 and WO2015 / 060299, after laminating a sheet-like carbon fiber bundle and a resin with a hot plate and sufficiently softening the resin on the sheet-like carbon fiber bundle, The impregnation can also be advanced by using a device that presses with a heated nip roll. The temperature of the hot plate for preheating, the surface temperature of the nip roll, the linear pressure of the nip roll, and the diameter and number of the nip rolls can be appropriately selected so as to obtain a desired impregnation degree. It is also possible to use an “S-wrap roll” in which a prepreg sheet travels in an S-shape as described in WO 2010/150022 pamphlet. In the present invention, “S-wrap roll” is simply referred to as “S-shaped roll”. WO 2010/150022 Pamphlet FIG. 1 shows an example in which the prepreg sheet runs in an S-shape, but if impregnation is possible, the contact length between the sheet and the roll, such as a U-shape, V-shape or Λ-shape, is described. May be adjusted. When the impregnation pressure is increased to increase the degree of impregnation, it is also possible to add an opposing contact roll. Further, as shown in FIG. 4 of the pamphlet of WO2015 / 076981, it is possible to improve the impregnation efficiency by arranging the conveyor belt opposite to the “S-wrap roll”, thereby increasing the production speed of the prepreg. Further, as described in WO 2017/068159 pamphlet or JP-A-2006-20397, etc., it is possible to improve the impregnation efficiency by applying ultrasonic waves to the prepreg before impregnation and rapidly raising the temperature of the prepreg. is there. Further, as described in JP-A-2017-154330, it is also possible to use an impregnation device that vibrates a plurality of “ironing blades” with an ultrasonic generator. Further, it is also possible to fold and impregnate the prepreg as described in JP-A-2013-22868.

<Simple additional impregnation>
In the above, the example of applying the conventional additional impregnation device was shown, but there is a case where the temperature of the prepreg is still high immediately below the application section, and in such a case, after leaving the application section, not much time has passed. When the additional impregnation operation is added at the stage, a heating device such as a hot plate for reheating the prepreg can be omitted or simplified, and the impregnation device can be greatly simplified and downsized. Such an impregnating device located immediately below the coating section is referred to as a simple additional impregnating device. As a simple additional impregnating device, a heating nip roll or a heated S-shaped roll can be used, but the roll diameter, the set pressure, and the contact length between the prepreg and the roll can be reduced as compared with a normal impregnating device, and the device can be downsized. This is preferable because power consumption can be reduced as much as possible.

  In addition, it is preferable that a release sheet be provided to the prepreg before the prepreg enters the simple additional impregnation device, because the running property of the prepreg is improved.

<Prepreg>
In the prepreg obtained by the production method of the present invention, the impregnation ratio of the coating liquid is preferably 10% or more. The impregnation rate of the coating liquid can be checked by tearing the collected prepreg and visually inspecting the inside, and more quantitatively, for example, by a peeling method. The impregnation rate of the coating liquid by the peeling method can be measured as follows. That is, the collected prepreg is sandwiched between adhesive tapes, peeled off, and the reinforcing fibers to which the coating liquid has adhered and the reinforcing fibers to which the coating liquid has not adhered are separated. Then, the ratio of the mass of the reinforcing fibers to which the coating liquid has adhered to the mass of the whole reinforcing fiber sheet put therein can be taken as the impregnation rate of the coating liquid by the peeling method.

<Prepreg width>
Since the prepreg, which is one of the precursors of FRP, is one form of the prepreg obtained by the present invention, the prepreg will be described below as a prepreg when the present invention is applied to FRP applications.

  The width of the prepreg is not particularly limited, and may be a wide width of about several tens cm to 2 m or a tape having a width of several mm to several tens mm. The width can be selected according to the application. In recent years, devices called ATL (Automated Tape Laying) or AFP (Automated Fiber Placement) for automatically laminating narrow prepregs and prepreg tapes have been widely used in order to increase the efficiency of the prepreg lamination process. Therefore, it is also preferable that the width is adjusted to this.

  There is no particular limitation on a method of obtaining a prepreg having a desired width, and a method of slitting a wide prepreg having a width of about 1 m to 2 m into a narrow width can be used. Further, in order to simplify or omit the slitting step, the width of the coating portion used in the present invention can be adjusted so as to have a desired width from the beginning. For example, when manufacturing a narrow prepreg having a width of 30 cm for ATL, the width of the application section outlet may be adjusted accordingly.

<Slit>
The method of slitting the prepreg is not particularly limited, and a known slit device can be used. After winding the prepreg once, it may be installed in the slit device again to perform slitting, or for efficiency, a slitting step may be arranged continuously from the prepreg producing step without winding the prepreg once. Also, in the slitting step, a wide prepreg of 1 m or more may be directly slit to a desired width, or once cut and divided into narrow prepregs of about 30 cm, and then slit again to a desired width. good.

<Coating liquid supply mechanism>
In the present invention, the coating liquid is stored in the coating section, but it is preferable to appropriately supply the coating liquid because the coating proceeds. The mechanism for supplying the coating liquid to the coating unit is not particularly limited, and a known device can be used. It is preferable that the coating liquid is continuously supplied to the coating section because the running of the reinforcing fiber sheet can be stabilized without disturbing the upper liquid level of the coating section. For example, self-weight can be supplied as a driving force from a tank storing the coating liquid, or can be supplied continuously using a pump or the like. As the pump, a gear pump, a tube pump, a pressure pump, or the like can be used as appropriate according to the properties of the coating liquid. When the coating liquid is solid at room temperature, it is preferable to provide a melter above the reservoir. Further, a continuous extruder or the like can be used. Further, it is preferable to provide a mechanism capable of continuously supplying the coating liquid in accordance with the amount of the coating liquid so that the liquid level above the coating portion of the coating liquid is as constant as possible. For this purpose, for example, a mechanism that monitors the liquid level, the weight of the application section, and the like and feeds it back to the supply device is conceivable.

<Online monitoring>
Further, it is preferable to provide a mechanism capable of online monitoring of the application amount for monitoring the application amount. The online monitoring method is not particularly limited, and a known method can be used. For example, as a device for measuring the thickness, for example, a beta-ray meter or the like can be used. In this case, it is possible to estimate the coating amount by measuring the thickness of the reinforcing fiber sheet and the thickness of the prepreg and analyzing the difference. The application amount monitored online is immediately fed back to the application unit, and can be used for adjusting the temperature of the application unit and the gap D (see FIG. 2) of the constricted portion 23. Application amount monitoring can of course be used as defect monitoring. As the thickness measurement position, for example, in FIG. 14, the thickness of the reinforcing fiber sheet 416 can be measured in the vicinity of the direction change roll 419, and the thickness of the prepreg can be measured between the application section 430 and the direction change roll 441. It is also preferable to perform online defect monitoring using infrared rays, near infrared rays, a camera (image analysis), or the like.

  The coating apparatus of the present invention has a traveling mechanism for causing the reinforcing fiber sheet to travel substantially vertically downward, and an application mechanism, wherein the application mechanism can store a coating liquid therein, and is further communicated with each other. Liquid pool portion and a constricted portion, the liquid reservoir portion has a portion whose cross-sectional area continuously decreases along the running direction of the reinforcing fiber sheet, and the constricted portion has a slit-shaped cross section. Having a cross-sectional area smaller than the upper surface of the liquid reservoir, and having a constricted surface forming the constricted portion, and an atmosphere-opening surface that is open to the atmosphere adjacent to the constricted portion. The surface forming the tip has a surface roughness Rz of 0.005 μm or more and 5 μm or less.

  Hereinafter, the present invention will be described in more detail with a specific example of the production of a prepreg using the coating apparatus, as an example of a prepreg which is one embodiment of the prepreg. Note that the following is an example, and the present invention is not construed as being limited to the embodiments described below.

  FIG. 14a is a schematic diagram of an example of a prepreg manufacturing process / apparatus using the present invention when a UD substrate is used as a reinforcing fiber sheet. The plurality of reinforcing fiber bobbins 412a are hung on a creel 411a, and are drawn upward through a direction changing guide 413a. At this time, the reinforcing fiber bundle 414 can be pulled out with a constant tension by the brake mechanism provided to the creel. The plurality of pulled out reinforcing fiber bundles 414 are orderly arranged by the reinforcing fiber arrangement device 415, and the reinforcing fiber sheet 416 is formed. In FIG. 14a, only three yarns are drawn on the reinforcing fiber bundle, but in practice, it can be made from two yarns to several hundred yarns, and can be adjusted to have a desired prepreg width and fiber weight. is there. Thereafter, the sheet is conveyed vertically downward through a widening device 417, a smoothing device 418, and a direction change roll 419. In FIG. 14 a, the reinforcing fiber sheet 416 is transported linearly between the reinforcing fiber arranging devices 415 to the turning roll 419. As the widening device 417 and the smoothing device 418, known devices can be used or can be appropriately skipped according to the purpose, or the devices can be omitted. The arrangement order of the reinforcing fiber arrangement device 415, the widening device 417, and the smoothing device 418 can be appropriately changed according to the purpose. The reinforcing fiber sheet 416 travels vertically downward from the direction changing roll 419, and reaches the direction changing roll 441 via the reinforcing fiber preheating device 420 and the application unit 430. The application section 430 can adopt any application section shape as long as the object of the present invention is achieved. For example, the shapes as shown in FIG. 2 and FIGS. Further, a bush can be provided as shown in FIG. 7 if necessary. Further, as shown in FIG. 15, a bar can be provided in the application section. In FIG. 14A, the release sheet 446 unwound from the release sheet (upper) supply device 442 can be laminated on a prepreg, in this case, a prepreg 471, on a direction change roll 441 to form a sheet-like integrated body. Furthermore, the release sheet 446 unwound from the release sheet (lower) supply device 443 can be inserted into the lower surface of the sheet-like integrated body. Here, release paper, release film, or the like can be used as the release sheet. This can be taken off by the high tension take-up device 444. In FIG. 14a, a nip roll is drawn as the high tension take-up device 444. Thereafter, the sheet-like integrated material passes through an additional impregnating device 450 provided with a hot plate 451 and a heating nip roll 452, is cooled by a cooling device 461, is taken off by a take-off device 462, and peels off the upper release sheet 446. Then, a sheet-like integrated body 472 composed of a prepreg / release sheet as a product can be obtained by winding with a winder 464. Since the sheet-like integrated object is conveyed in a basic straight line from the direction changing roll 441 to the winder 464, generation of wrinkles can be suppressed. In FIG. 14A, illustrations of the coating liquid supply device and the online monitoring device are omitted. FIG. 14b shows an apparatus when a reinforcing fiber fabric is used as a reinforcing fiber sheet. It has the same configuration as that of FIG. 14A except that an unwinding device is used for 411b, a reinforcing fiber fabric roll for 412b, and a nip roll for 413b.

  FIG. 15a is a schematic view of another example of a prepreg manufacturing process / apparatus using the present invention when a UD substrate is used as a reinforcing fiber sheet. In FIG. 15a, the reinforcing fiber bundle 414 is pulled out from the creel 411a, and the reinforcing fiber sheet 416 is formed as it is by the reinforcing fiber arrangement device 415, and then is linearly conveyed to the widening device 417 and the smoothing device 418. FIG. 14A is different from FIG. 14A in that the sheet 416 is guided upward. With such a configuration, it is not necessary to install the device above, and the installation of a scaffold or the like can be greatly simplified.

  FIG. 16a is a schematic view of another example of a prepreg manufacturing process / apparatus using the present invention when a UD substrate is used as a reinforcing fiber sheet. In FIG. 16a, a creel 411a is installed on the floor, and the running path of the reinforcing fiber sheet 416 is further linearized.

  FIG. 17a is a schematic view of another example of a prepreg manufacturing process / apparatus using the present invention when a UD substrate is used as a reinforcing fiber sheet. An example in which a simple additional impregnation device is used instead of the normal additional impregnation device shown in FIG. 14A is shown. In FIG. 17 a, since the simple additional impregnation device 453 is installed immediately below the coating unit 430, the prepreg 471 is guided to the simple additional impregnation device 453 in a high temperature state, so that the impregnation device can be simplified and downsized. In FIG. 17a, the heating nip roll 454 is drawn as an example, but a small heating S-shaped roll may be used depending on the purpose. The use of the simple additional impregnation apparatus is also advantageous in that the entire prepreg manufacturing apparatus can be made very compact.

  FIGS. 15a, 16a, and 17a are schematic diagrams of another example of a prepreg manufacturing process / apparatus when a unidirectional array reinforcing fiber bundle is used as a reinforcing fiber sheet as in FIG. 14a. As shown in FIG. 15b, FIG. 16b, and FIG. 17b, the unwinding device is used for 411b, the reinforcing fiber fabric roll is used for 412b, and the nip roll is used for 413b, so that each device can be used for the reinforcing fiber fabric as in FIG. 14b.

  FIG. 18 is a schematic view of another example of a prepreg manufacturing process / apparatus using the present invention. FIG. 19 shows an example in which a high tension take-up S-shaped roll 449 is used as a high tension take-up device, and two S-2 rolls 455 of “S-wrap roll” type are used as the additional impregnating device (two in total). Although the drawing is performed, the number of rolls can of course be increased or decreased according to the purpose. Further, in FIG. 19, a contact roll 456 for enhancing the impregnation effect is also drawn, but it is of course possible to omit it depending on the purpose.

  FIG. 19 is a schematic view of another example of a prepreg manufacturing process / apparatus using the present invention. In this example, an example is shown in which a heated S-shaped roll of the "S-wrap roll" type is also used as a high tension take-up device. There is an advantage that the entire prepreg manufacturing apparatus can be made very compact.

[Surface roughness]
The maximum height Rz was measured using a Mitutoyo surface roughness measuring instrument (SV-C4500S4) according to JIS B0601 (2001).

  Each of the evaluation methods was determined as follows. In each case, “「 ”,“ ○ ”, and“ △ ”were passed, and“ × ”was rejected.

[Running stability]
In order to evaluate the running stability (continuous productivity) of the reinforced fiber sheet in the coating liquid application section, continuous running was performed for 60 minutes, and if there was no fuzz clogging or yarn breakage, "◎" was continuously run for 60 minutes. There was no clogging or thread breakage, but the dispensed part was disassembled and the liquid contact surface of the wall member 21 was visually observed. In the coating liquid, fluff was visually observed. The result is indicated by "x".

[Break of fiber bundle]
When the end of the reinforcing fiber sheet is not broken or deformed at all, "◎" is shown. When the end is not slightly problematic, occasionally the end is slightly broken or deformed. The problematic end was broken or deformed, but the time that was less than 30 minutes was changed to "△". The end was problematic in continuous running for 60 minutes. Was 30 minutes or more, was rated "x".

[Weight-wise basis weight measurement]
The prepreg is cut in the width direction (perpendicular to the sheet running direction) into a strip having a width of 25 mm and a length of 200 mm. The mass of the resin composition of the obtained strip-shaped sheet is measured to the third decimal place by an electronic balance to obtain the mass of the resin composition. By returning dividing the mass by the area of the strip, to obtain a resin composition having a basis weight per 1 m ^2. This operation is performed from the end of the prepreg to the opposite end, and the average, maximum, and minimum values of the obtained resin composition are calculated except for both ends, and (maximum value−minimum value) ÷ average value Was calculated to determine the basis weight variation. This operation was performed a total of three times at intervals of 1 m in the longitudinal direction, and the average value of the obtained areal variation was defined as the areal variation of the resin-impregnated reinforced fiber sheet. For example, in the case of a resin sheet having a width of 350 mm, 14 strips are obtained, and values for 12 strips are obtained except for both end portions. When it was larger than 20%, it was evaluated as "x".

[Example 1]
A coating liquid A composed of the following epoxy resin was used as the coating liquid.

  As the application unit, an application unit of the application unit 20c type shown in FIG. 9 was used, and an apparatus having a configuration shown in FIG. 20a (a resin supply unit was omitted) was used as a prepreg manufacturing apparatus. In the application part 20c, a stainless steel block was used for the wall members 21e and 21f forming the liquid reservoir 22 and the constricted part 23, and a stainless steel plate was used for the side plate members 24a and 24b. In order to further heat the coating liquid, a plate heater is attached to the outer periphery of the wall members 21e, 21f and the side plate members 24a, 24b, and the temperature and viscosity of the coating liquid are adjusted while measuring the temperature with a thermocouple. Was carried out at a temperature of 90 ° C. The running direction of the carbon fiber sheet 1a was vertically downward Z, and the liquid reservoir 22 was tapered (taper opening angle 60 °, taper height (ie, H) 100 mm). The width of the liquid reservoir 22 was 306 mm. The gap D of the constriction 23 was 0.2 mm. In this case, the aspect ratio of the exit slit is 1500. In addition, in order to prevent the coating liquid from leaking from the stenotic portion outlet, the lower surface of the stenotic portion outlet was closed with the outside of the bush being used. The surface forming the tip of the constriction was processed so that the surface roughness Rz was 0.5 μm.

  The prepreg was prepared by using a carbon fiber (“Torayca (registered trademark)” T800S (24K) manufactured by Toray Co., Ltd.) as a reinforcing fiber, using a thermosetting epoxy resin composition described later as a coating liquid, and using the above apparatus to prepare a CFRP sheet. A prepreg was prepared. The number of the reinforcing fiber bobbins 412a was changed according to the prepreg to be produced, but was set to 56 unless otherwise specified.

  The reinforcing fiber sheet 1a was caused to travel vertically downward, and passed through the liquid reservoir 22 and the narrowed portion 23. The running speed was 20 m / min.

  The reinforcing fiber bundle 414 was pulled out from the plurality of reinforcing fiber bobbins 412 a hung on the creel 411 a, the reinforcing fiber sheet 416 was formed by the reinforcing fiber arrangement device 415, and once guided upward by the direction change roll 419. Thereafter, the reinforcing fiber sheet 416 is conveyed vertically downward through the direction change roll 419, heated to a temperature equal to or higher than the application unit temperature by the reinforcing fiber preheating device 420, guided to the application unit 430, and the following coating liquid A is applied. . Thereafter, the prepreg (prepreg) 471 was pulled out from the application section 430, stacked on the direction change roll 441 with the upper release sheet 446 (release paper in this case), and taken up by the high tension take-off S-shaped roll 449. Then, the lower release sheet 446 (release paper in this case) was supplied to the upper roll of the high tension take-off S-shaped roll 449, and a sheet-like integrated body in which the prepreg was sandwiched by the release paper was formed. Further, this was guided to an additional impregnation device 450 provided with a hot plate 451 and a heating nip roll 452, and additional impregnation was performed in some cases. Thereafter, the upper release paper was peeled off via the cooling device 461, and the sheet-like integrated material 472 was wound.

  Table 1 shows various stable running evaluation items at this time. The carbon fiber impregnated with the coating liquid was quickly obtained immediately below the coating apparatus, and the impregnating property of the coating liquid was visually checked, and it was confirmed that the fibers inside the carbon fiber impregnated with the coating liquid were wet with the coating liquid. It was also confirmed that the appearance was good.

<Coating liquid>
Thermosetting epoxy resin composition 1 (coating liquid A):
It is a mixture of an epoxy resin (a mixture of an aromatic amine type epoxy resin and a bisphenol type epoxy resin), a curing agent (diaminodiphenyl sulfone), and a polyether sulfone, and does not contain polymer particles. The viscosity of the thermosetting epoxy resin 1 was measured using ARES-G2 manufactured by TA Instruments at a measurement frequency of 0.5 Hz and a heating rate of 1.5 ° C./min. At 15 ° C. and 4 Pa · s at 105 ° C.

<Reinforced fiber fabric>
Carbon fiber fabric (Toray “Torayca” cloth C6343B)
Carbon fiber: Trading card T300B (3K))
Woven structure: plain weave density: 12.5 strands / 25 mm Weft density: 12.5 strands / 25 mm
Weight: 198 g / m ² Thickness: 0.23 mm

[Examples 2 to 8]
The evaluation was performed in the same manner as in Example 1 except that the surface roughness Rz of the surface forming the distal end of the constriction was changed as shown in Table 1. At any level, samples with evaluations higher than usable could be collected. Table 1 shows the results.

[Comparative Example 1]
FIG. 12 is a detailed cross-sectional view of a coating unit 30 according to another embodiment different from the present invention. Unlike the embodiment of the present invention, the liquid reservoir 32 in FIG. 10 does not include a region where the cross-sectional area decreases continuously in the vertical downward direction Z, and the cross-sectional area is intermittent at the boundary 33 with the constriction 23 ( This is a configuration that decreases rapidly. When the coating liquid A was applied to the reinforcing fiber sheet 1a using the application unit 30 under the same conditions as in Example 1, the reinforcing fiber sheet 1a was placed inside the application unit 30 immediately after the running at a running speed of 20 m / min. And it became impossible to run. Then, when the application part 30 was disassembled and the inside was confirmed, it was confirmed that a large amount of fluff was clogged at the boundary 33 between the liquid pool part 32 and the constricted part 23. Table 2 shows the results.

[Comparative Examples 2 and 3]
The evaluation was performed in the same manner as in Example 1 except that the surface roughness Rz of the surface forming the distal end of the stenosis portion was set in Table 2. Although there was no problem in running stability, the variation in the basis weight was large, and the appearance was confirmed. As a result, it was confirmed that the coating liquid had a streak shape. Table 2 shows the results.

[Examples 8 and 9]
Evaluation was performed in the same manner as in Example 1 except that the width of the liquid pool 22 was changed as shown in Table 3. At any level, samples with evaluations higher than usable could be collected. Table 3 shows the results.

[Examples 10 and 11]
As a width regulating mechanism, a plate-shaped bush 27 adapted to the inner shape of the application section as shown in FIG. 7 is provided, and the installation position of the plate-shaped bush is changed freely. An experiment was performed in the same manner as in Example 8, except that the following conditions were satisfied. At any level, samples with evaluations higher than usable could be collected. Table 4 shows the results.

[Example 12]
Using the apparatus shown in FIG. 20b, a prepreg was produced using a carbon fiber fabric obtained by cutting the carbon fiber fabric into a 300 mm width as the reinforcing fiber fabric. An experiment was performed in the same manner as in Example 1 except that a reinforcing fiber fabric was used for unwinding, and the gap D of the narrowed portion 23 of the application portion was set to 0.3 mm. That is, the application portion, the impregnated portion, and the transport winding portion other than the gap are the same as those in the first embodiment. Table 5 shows the results.

Example 13
Evaluation was performed in the same manner as in Example 1 except that the surface roughness Rz of the surface forming the distal end of the constriction was changed as shown in Table 5. Samples with evaluations higher than usable could be collected. Table 5 shows the results.

[Examples 14 and 15, Comparative Example 4]
The sheet-like integrated product made of the prepreg / release paper having a width of 300 mm obtained in Example 1 and Example 2 was slit to obtain a prepreg tape having a width of 7 mm. Since the impregnation of the prepreg tapes of Example 1 and Example 2 was sufficiently advanced, adhesion of the resin to the cutter blade of the slitter was small. On the other hand, in the prepreg tape of Comparative Example 2, meandering occurred during cutting in the slitter.

[Examples 16 to 19, Reference Example 1]
Six layers of the prepregs and prepreg tapes obtained in Examples 1 to 4 were laminated and cured at 180 ° C. and 6 kgf / cm ² (0.588 MPa) for 2 hours using an autoclave to obtain CFRP (Examples 18 to 18). 21). Each of the obtained CFRPs had a tensile strength in the range of 2.8 GPa to 3.1 GPa, and had mechanical properties suitable as structural materials for aerospace.

A prepreg prepared by the conventional hot melt method using the carbon fiber and the thermosetting epoxy resin 1 (coating liquid A) used in Example 1 was used at 180 ° C., 6 kgf / cm ² (0.588 MPa) using an autoclave. ) Had a tensile strength of 2.92 GPa (Reference Example 1).

  The CFRP tensile strength was measured in the same manner as in WO2011 / 118106, and the value obtained by standardizing the volume% of the reinforcing fibers in the prepreg to 56.5% was used.

  The prepreg obtained by the production method of the present invention is a FRP typified by CFRP, and is a structural material or interior material for aerospace applications, automobiles, trains, ships, etc., a pressure vessel, an industrial material application, a sports material application, a medical device. It can be widely used for applications, housing applications, civil engineering and construction applications.

REFERENCE SIGNS LIST 1 reinforcing fiber 1a reinforcing fiber sheet 1b prepreg 2 coating liquid 3 release sheet 11a creel 11b unwinding device 12a array device 12b nip rolls 13, 14 transport roll 15 winding device 16 release sheet supply device 20 coating unit 20b Another embodiment Coating part 20c of another embodiment Coating part 20d of another embodiment Coating part 20e of another embodiment Coating parts 21a and 21b of another embodiment Wall members 21c and 21d Wall members 21e and 21f of different shapes Wall members of different shapes 21g, 21h Differently shaped wall members 21i, 21j Differently shaped wall members 22 Liquid reservoir 22a Region in which cross-sectional area decreases continuously in liquid reservoir 22b Region 22c in which cross-sectional area does not decrease in liquid reservoir A region 23 of the liquid reservoir where the cross-sectional area is intermittently reduced 23 Narrowing portions 24a, 24b Side plate member 25 Outlet 26 Gap 27 Plate Bush 27a One end 27b of width regulating mechanism One end 30 different from 27a of width regulating mechanism 30 Coating portions 31a and 31b of Comparative Example 1 Wall member 32 of Comparative Example 1 Liquid reservoir 33 of Comparative Example 1 Liquid reservoir 33 of Comparative Example 1 Of these, the areas 35a, 35b, and 35c where the cross-sectional area decreases intermittently. C The height D to the upper liquid surface of the liquid reservoir 22 D The gap G between the constrictions The position H where the width is regulated The vertical height I where the cross-sectional area of the liquid reservoir 22 continuously decreases I The wall height L The liquid Width M of reservoir 22 Distance R to wall surface R, Ra, Rb Vortex flow T Circulation flow U Coating liquid flow W near corner formed by intersection of constricted surface and open air surface Coating liquid impregnation measured just below constricted portion 23 The width Y constricted portion 23 of the reinforcing fiber sheet 1b Width Z running direction of the reinforcing fiber sheet 1a (vertically downward)
θ Taper opening angle 411a Creel 411b Unwinding device 412a Reinforcement fiber bobbin 413a Redirection guide 414 Reinforcement fiber bundle 415 Reinforcement fiber arrangement device 416 Reinforcement fiber sheet 417 Widening device 418 Smoothing device 419 Redirection roll 420 Reinforcement fiber preheating device 430 Coating section 431 First coating section 432 Second coating section 441 Direction change roll 442 Release sheet (upper) supply device 443 Release sheet (lower) supply device 444 High tension take-up device 445 Direction change roll 446 Release sheet 447 Laminating roll 448 High tension take-up device 449 High tension take-off S-shaped roll 450 Additional impregnating device 451 Heating plate 452 Heating nip roll 453 Simple additional impregnating device 454 Heating nip roll 455 Heating S-shaped roll 456 Contact roll 461 Cooling device 462 Pulling-in 463 release sheet (upper) winding device 464 winder 471 prepreg 472 prepreg / release sheet (sheet-like integrated product)

Claims (16)

  A method for producing a prepreg for applying a coating liquid to a reinforcing fiber sheet by passing a reinforcing fiber sheet substantially vertically downward inside an application section in which a coating liquid is stored, wherein the application sections are communicated with each other. Liquid pool portion and a constricted portion, the liquid reservoir portion has a portion whose cross-sectional area is continuously reduced along the running direction of the reinforcing fiber sheet, the constricted portion has a slit-shaped cross section, and A method for producing a prepreg, wherein the prepreg has a cross-sectional area smaller than an upper surface of a liquid reservoir portion, and a surface roughness Rz of a surface forming a tip of the constricted portion is 0.005 μm or more and 5 μm or less.   The prepreg manufacturing method according to claim 1, wherein a width L of a lower portion of the liquid reservoir in a direction in which the reinforcing fibers are arranged and a width W of the reinforcing fiber sheet immediately below the constriction satisfy L ≦ W + 10 (mm).   A width regulating mechanism for regulating the width of the reinforcing fiber sheet is provided in the liquid reservoir. The width (W) of the reinforcing fiber sheet immediately below the constriction and the width (L2) regulated by the width regulating mechanism at the lower end of the width regulating mechanism. The method for producing a prepreg according to claim 1, wherein the relationship with L) satisfies L2 ≦ W + 10 (mm).   4. The method for producing a prepreg according to claim 3, wherein the width regulating mechanism is provided over the entire area of the liquid pool and the constriction.   The method for producing a prepreg according to any one of claims 1 to 4, wherein the coating liquid contains a thermosetting resin.   Using a coating liquid containing polymer particles, and keeping the temperature of the coating liquid in the coating section at least 20 ° C. lower than the glass transition temperature (Tg) or melting point (Tm) of the resin constituting the polymer particles. A method for producing a prepreg according to any one of claims 1 to 5, wherein the method is applied to a reinforcing fiber sheet.   The method for producing a prepreg according to any one of claims 1 to 6, wherein the reinforcing fiber sheet is heated and then guided to a liquid reservoir.   The method for producing a prepreg according to any one of claims 1 to 7, wherein the reinforcing fiber sheet is guided to a liquid pool after smoothening treatment.   The method for producing a prepreg according to any one of claims 1 to 8, wherein after the reinforcing fiber sheet is subjected to a widening process, the reinforcing fiber sheet is guided to a liquid reservoir.   A prepreg is obtained by the method for producing a prepreg according to any one of claims 1 to 9, and a release sheet is applied to at least one surface of the obtained prepreg to form a sheet-like integrated body. A method for producing a sheet-like monolith.   The method for producing a sheet-like integrated body according to claim 10, wherein the additional impregnation is performed after the sheet-like integrated body is formed.   A coating device for applying a coating liquid to a reinforcing fiber sheet, comprising a traveling mechanism for causing the reinforcing fiber sheet to travel substantially vertically downward, and a coating mechanism, wherein the coating mechanism stores the coating liquid therein. A liquid reservoir and a constriction, which are communicated with each other, wherein the liquid reservoir has a portion having a continuously decreasing cross-sectional area along a running direction of the reinforcing fiber sheet; The coating has a slit-shaped cross section and a smaller cross-sectional area than the upper surface of the liquid reservoir, and has a surface roughness Rz of the surface forming the tip of the constricted portion of not less than 0.005 μm and not more than 5 μm. apparatus.   A mechanism for arranging reinforcing fibers to form a reinforcing fiber sheet, a mechanism for heating the reinforcing fiber sheet, a coating device according to claim 12, a supply device for a release sheet, a nip roll and / or an S-shaped roll, and a winder. Equipment for manufacturing sheet-like monoliths.   A prepreg manufactured by the manufacturing method according to any one of claims 1 to 11 and / or the manufacturing apparatus according to claim 12 or 13.   A prepreg tape obtained by slitting the prepreg according to claim 14.   A fiber-reinforced composite material obtained by molding the prepreg according to claim 14 and / or the prepreg tape according to claim 15.

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