JP7163927B2 - Prepreg manufacturing method, prepreg tape manufacturing method, and fiber reinforced composite material manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a prepreg, and more particularly to a method for uniformly impregnating a reinforcing fiber sheet with a matrix resin.

Fiber reinforced composite materials (FRP), which are made by reinforcing matrix resins containing thermoplastic resins and thermosetting resins with reinforcing fibers, are used in aerospace materials, automotive materials, industrial materials, pressure vessels, building materials, housings, medical It is used in various fields such as applications and sports applications. Carbon fiber reinforced composite materials (CFRP) are widely and preferably used when particularly high mechanical properties and lightness are required. On the other hand, glass fiber reinforced composite materials (GFRP) are sometimes used when cost is given priority over mechanical properties and lightness. In FRP, a reinforcing fiber bundle is impregnated with a matrix resin to obtain an intermediate base material, which is then laminated and molded, and when a thermosetting resin is used, it is thermally cured to produce a member made of FRP. In the above-mentioned applications, there are many flat objects and shapes formed by bending them, and as an intermediate base material for FRP, a two-dimensional sheet-like object is more suitable than a one-dimensional strand or roving-like object when producing a member. It is widely used from the viewpoint of lamination efficiency and formability.

In addition, 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-like intermediate base material can be obtained by slicing a wide sheet-like intermediate base material in a desired width, or by directly impregnating a narrow reinforcing fiber sheet with a matrix resin.

A prepreg is generally used as the two-dimensional sheet-like intermediate base material. A prepreg is produced by applying and impregnating a matrix resin to reinforcing fibers. As a reinforcing fiber sheet, a unidirectional material (UD base material) in which a plurality of reinforcing fibers are arranged in one direction on a surface, or a reinforcing fiber sheet in which reinforcing fibers are arranged in a multiaxial manner or randomly arranged. There is fabric.

The hot-melt method, which is one of the prepreg manufacturing methods, melts the matrix resin, coats it on the release paper, sandwiches it between the upper and lower surfaces of the reinforcing fiber sheet to create a laminated structure, and then heats and presses it. The inside of the reinforcing fiber sheet is impregnated with a matrix resin. This method involves a large number of steps, and the production speed cannot be increased, resulting in a problem of high cost.

As for improving the efficiency of impregnation, there have been proposals such as those disclosed in Patent Document 1, for example. In this method, glass fibers are melt-spun, bundled into strands or rovings, and passed through a liquid reservoir having a conical channel filled with a thermoplastic resin.

On the other hand, Patent Document 2 describes a method of simultaneously forming coating films on both sides of a sheet. , and then coated with a pipe-type doctor.

As a method for manufacturing strip-shaped prepreg using thermoplastic resin, a horizontal drawing method ( Patent Document 3) is known. In Patent Document 3, a plurality of band-shaped reinforcing fiber bundles are separately introduced into a die filled with a molten thermoplastic resin, spread, impregnated, and laminated by a fixed guide (for example, a squeeze bar), and finally 1 It is described to be drawn from a die as a single sheet of prepreg.

Patent Document 4 describes a device that applies ultrasonic vibrations to an outlet in a pultrusion method in which a manifold is filled with a thermoplastic resin and a reinforcing fiber bundle is pulled out vertically.

Further, Patent Document 5 describes blowing a thermoplastic resin onto a carbon fiber sheet using a so-called meltblowing method. Further, in Comparative Example 1 of Patent Document 5, it is described that a film slit die is used for a carbon fiber sheet to laminate PPS (polyphenylene sulfide), which is a thermoplastic resin.

International publication WO2001/028951 pamphlet JP-A-10-337516 International publication WO2012/002417 pamphlet JP-A-1-178412 International publication WO2003/091015 pamphlet

However, the method of Patent Document 1 can only produce strands and rovings, and cannot be applied to the production of sheet-like prepreg, which is the object of the present invention. Further, in Patent Document 1, in order to improve the impregnation efficiency, a thermoplastic resin fluid is applied to the side surface of the strand or roving-shaped reinforcing fiber bundle to actively generate turbulence 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, but if this idea is applied to the reinforcing fiber sheet, the reinforcing fiber sheet will deform and the quality of the prepreg will deteriorate. It is thought that not only does this decrease, but the mechanical properties of FRP also deteriorate.

Moreover, when the technique disclosed in Patent Document 2 is applied, fluff is generated due to abrasion by the web guide, and it is considered that the reinforcing fiber sheet becomes difficult to run. Further, the technique of Patent Document 2 is resin coating and impregnation is not intended.

Further, in the method of Patent Document 3, the fluff tends to stay in the liquid pool during continuous production, and the fluff tends to clog the pulling-out portion. In particular, when the band-like reinforcing fiber bundles are continuously run at high speed, the frequency of clogging with fluff increases significantly, so that production can only be performed at a very slow speed, resulting in a problem of poor productivity. In addition, in the case of the horizontal drawing method, the die part must be sealed in order to prevent liquid leakage, and collection of fluff during continuous production is not sufficient. Furthermore, in the horizontal drawing method, when the inside of the reinforcing fiber sheet is impregnated with the matrix resin, the air bubbles remaining inside the band-shaped reinforcing fiber bundle are removed by buoyancy in the direction perpendicular to the orientation direction of the reinforcing fiber bundle (band-shaped reinforcement Since the air bubbles are discharged in the thickness direction of the fiber bundle), the air bubbles are discharged by pushing away the impregnated matrix resin. Therefore, there is a problem that impregnation efficiency is low because movement of air bubbles is hindered by the liquid and the impregnation of the matrix resin is also hindered by the air bubbles. Furthermore, it has been proposed to exhaust air bubbles through a vent, but it is only in the vicinity of the die exit, and its effect is considered to be limited.

In addition, in the method described in Patent Document 4, a nozzle portion that is not filled with resin is provided at the top of the manifold, and the nozzle can be optimized with a strand or roving-like material, but a flat surface such as a reinforcing fiber sheet is used. It is difficult to deal with the shape, and when the reinforcing fiber sheet passes through here, fluff is generated, and if it is brought into the manifold, it is considered that the die is likely to clog.

The method disclosed in Patent Document 5 is inefficient because the matrix resin can be applied only to one side of the carbon fiber sheet.

Thus, an efficient method for imparting a matrix resin to a reinforcing fiber sheet, particularly an efficient method for producing a prepreg using a UD base material has not yet been established.

The object of the present invention is to provide a prepreg manufacturing method that suppresses the generation of fluff and enables continuous production without clogging of fluff. To provide a method for manufacturing a prepreg, which can increase the production speed, suppresses bending of the obtained prepreg, has a uniform basis weight, and is excellent in appearance and workability.

The prepreg manufacturing method of the present invention, which solves the above-mentioned problems, provides the matrix resin to the reinforcing fiber sheet by allowing the reinforcing fiber sheet to pass substantially downward in the vertical direction through the application section in which the matrix resin is stored. and then spray coating the primary prepreg withdrawn from the coating section, wherein the coating section comprises a liquid reservoir communicating with each other and a liquid reservoir below the liquid reservoir. a constricted portion located at a position , the liquid pooling portion has a portion where the cross-sectional area continuously decreases along the running direction of the reinforcing fiber sheet, the narrowing portion has a slit-shaped cross section, and the liquid pools A method for manufacturing a prepreg having a cross-sectional area smaller than the upper surface of a part.

In addition, the matrix resin is imparted to the reinforcing fiber sheet by passing the reinforcing fiber sheet substantially vertically downward into the application section in which the matrix resin is stored, and then the primary prepreg is pulled out from the application section. a prepreg manufacturing method for performing curtain coating in which a liquid is further discharged to the prepreg, wherein the coating section includes a liquid reservoir section communicating with each other and a constricted section positioned below the liquid reservoir section, and the liquid reservoir section is Production of a prepreg having a portion where the cross-sectional area continuously decreases along the running direction of the reinforcing fiber sheet, the constricted portion having a slit-shaped cross-section and a cross-sectional area smaller than the upper surface of the liquid pool. The method.

Further, a method for manufacturing a prepreg in which the matrix resin is applied to the reinforcing fiber sheet by passing the reinforcing fiber sheet substantially downward in the interior of the coating portion in which the matrix resin is stored, wherein the coating portions are mutually It comprises a communicating liquid reservoir and a constricted section positioned below the liquid reservoir , the liquid reservoir having a portion in which the cross-sectional area continuously decreases along the running direction of the reinforcing fiber sheet, The constricted portion has a slit-shaped cross section and has a smaller cross-sectional area than the upper surface of the liquid pooling portion, and before the reinforcing fiber sheet is passed through the application portion, the reinforcing fiber sheet is treated with a thread splitting prevention agent to improve toughness. A method for producing a prepreg by applying at least one modifier selected from the group consisting of a modifier, a flame retardant and a fluff sizing agent.

A method for manufacturing a prepreg tape of the present invention is characterized by slitting the prepreg obtained by the method for manufacturing a prepreg.

Furthermore, a method for producing a fiber-reinforced composite material of the present invention is characterized by molding a prepreg obtained by the method for producing a prepreg or a prepreg tape obtained by the method for producing a prepreg tape.

According to the prepreg manufacturing method of the present invention, clogging due to fluff can be greatly suppressed and prevented. Furthermore, the reinforcing fiber sheet can be run continuously and at high speed, improving the productivity of the prepreg.

Furthermore, in one of the embodiments of the present invention, another substance can be added to the surface of the prepreg, so that the physical properties and functionality of the prepreg and the FRP obtained therefrom can be improved. Further, when the same resin as the matrix resin is used instead of the other substance, process stability and quality can be improved.

In another embodiment, a modifier can be applied to the reinforcing fiber sheet before applying the matrix resin, so that the physical properties and functionality of the FRP can be improved, and the process stability and quality can be improved. can be improved.

1 is a schematic cross-sectional view showing a prepreg manufacturing method and a coating apparatus according to an embodiment of a first manufacturing method of the present invention; FIG. FIG. 4 is a schematic cross-sectional view showing a prepreg manufacturing method and a coating apparatus according to an embodiment of the second manufacturing method of the present invention. It is a detailed cross-sectional view enlarging the portion of the application part 20 in FIGS. 1a and 1b. FIG. 3 is a bottom view of the application unit 20 in FIG. 2 as seen from the direction of A in FIG. 2 ; FIG. 3 is a cross-sectional view illustrating the internal structure of the application section 20 in FIG. 2 when viewed from the direction of B in FIG. 2 ; 4B is a cross-sectional view showing the flow of the matrix resin 2 in the gap 26 in FIG. 4A. FIG. It is a figure which shows the installation example of a width control mechanism. FIG. 3 is a detailed cross-sectional view of an application portion 20b of another embodiment different from that of FIG. 2; FIG. 7 is a detailed cross-sectional view of an application portion 20c of another embodiment different from that of FIG. 6; FIG. 7 is a detailed cross-sectional view of an application section 20d of another embodiment different from that of FIG. 6; FIG. 7 is a detailed cross-sectional view of an application portion 20e of another embodiment different from that of FIG. 6; FIG. 4 is a detailed cross-sectional view of an application section 30 of an embodiment different from the present invention; FIG. 4 is a diagram showing a mode in which a bar is provided inside a liquid pool portion, which is an example of an embodiment of the present invention; It is a schematic diagram showing an example of a spray coating process used in the present invention. FIG. 4 is a schematic diagram for explaining the spinning behavior of the discharged liquid and its solidified product when the coating height h is lowered in the spray coating process used in the present invention. FIG. 4 is a schematic diagram for explaining the spinning behavior of the discharged liquid and its solidified product when the coating height h is increased in the spray coating process used in the present invention. FIG. 4 is a side view of the case where the coating angle is 90° in the curtain coating process used in the present invention. FIG. 4 is a side view of the curtain coating apparatus tilted at a coating angle of α° in the curtain coating process used in the present invention. FIG. 4 is a front view for explaining the state of the edge of the film (with airflow control) in the curtain coating process used in the present invention; FIG. 4 is a top view of the vicinity of the curtain coating process used in the present invention. FIG. 10 is a side view for explaining the state of the surface of the film (without airflow control) in the curtain coating process used in the present invention; FIG. 10 is a side view for explaining the state of the surface portion of the film (with airflow control) in the curtain coating process used in the present invention; FIG. 2 is a side view showing an example of a curtain coating apparatus used in the present invention, which is provided with airflow control means. FIG. 4 is a side view of coating on a roll in the curtain coating process used in the present invention. It is a figure which shows the example of the aspect which comprises the simple impregnation apparatus which concerns on one Embodiment of this invention. FIG. 4 is a diagram showing an example of a mode having a plurality of application units according to one embodiment of the present invention; It is a figure which shows the example of the aspect which laminates|stacks several prepregs which concern on one Embodiment of this invention. FIG. 10 is a diagram illustrating an example of another aspect comprising a plurality of applicators according to an embodiment of the present invention; BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic which shows the example of a prepreg manufacturing process and apparatus using the 1st manufacturing method of this invention. FIG. 3 is a schematic diagram of another example of a prepreg manufacturing process/apparatus using the first manufacturing method of the present invention; It is a schematic diagram showing an example of a prepreg manufacturing process and apparatus using the second manufacturing method of the present invention. It is a schematic diagram showing an example of a prepreg manufacturing process and apparatus using the second manufacturing method of the present invention. FIG. 4 is a schematic diagram showing an example of another prepreg manufacturing process/apparatus using the second manufacturing method of the present invention. FIG. 4 is a schematic diagram showing an example of another prepreg manufacturing process/apparatus using the second manufacturing method of the present invention. FIG. 4 is a schematic diagram showing an example of another prepreg manufacturing process/apparatus using the second manufacturing method of the present invention. FIG. 4 is a schematic diagram showing an example of another prepreg manufacturing process/apparatus using the second manufacturing method of the present invention. FIG. 4 is a schematic diagram showing an example of another prepreg manufacturing process/apparatus using the second manufacturing method of the present invention. FIG. 29B is a schematic diagram showing an example of using spray coating as a modifying agent application device in FIG. 29a. FIG. 35b is a schematic view of the state of applying the modifier in FIG. 35a, viewed from the direction of M in FIG. 35a; FIG. 29B is a schematic diagram showing an example of using a melt blower as a modifier application device in FIG. 29a. FIG. 36b is a schematic view of the state of applying the modifier in FIG. 36a, viewed from the direction of M in FIG. 36a; FIG. 29B is a schematic diagram showing an example of using curtain coating as a modifier application device in FIG. 29a. FIG. 37b is a schematic view of the state of applying the modifier in FIG. 37a, viewed from the direction of M in FIG. 37a; 37a is a schematic diagram showing an example of using a surface coating device as a modifier applying device in FIG. 29a of another embodiment. FIG. FIG. 38b is a schematic view of the state of applying the modifier in FIG. 38a, viewed from the direction of M in FIG. 38a;

Preferred embodiments of the present invention will be described with reference to the drawings. It should be noted that the following description exemplifies the embodiments of the invention, and the present invention is not to be construed as being limited thereto, and various modifications are possible without departing from the object and effect of the present invention. .

<Overview of prepreg manufacturing method>
The present invention is characterized by the method of applying the matrix resin to the reinforcing fiber sheet. Further, in order to stabilize this process and improve the functionality and quality of the resulting prepreg, before and after the application and impregnation of the matrix resin, Furthermore, a resin, a modifier, etc. are added.

First, referring to FIG. 1a, the outline of the first manufacturing method of the present invention, in which coating is further applied after application of the matrix resin, will be described. FIG. 1a is a schematic cross-sectional view showing a prepreg manufacturing method and apparatus according to an embodiment of the first manufacturing method of the present invention. The coating device 100 includes transport rolls 13 and 14, which are running mechanisms for running the reinforcing fiber sheet 1a substantially downward in the vertical direction Z, and is provided between the transport rolls 13 and 14, and the matrix resin 2 is accumulated. An application unit 20 is provided. In addition, before and after the coating device 100, a plurality of creels 11 for unwinding the reinforcing fibers 1, and a reinforcing fiber sheet 1a in which the unwound reinforcing fibers 1 are arranged in one direction (arranged in the depth direction of the paper surface in FIG. 1a). and a winding device 15 for the prepreg 1c. The coating device 100 is also equipped with a matrix resin supply device (not shown). Further, supply devices 16a and 16b for supplying release sheets 3a and 3b are provided. After forming the primary prepreg 1c, a spray coating device 41 and a curtain coating device 42 are arranged. Either one of the spray coating device 41 and the curtain coating device 42 may be used, or both may be used. Moreover, when both are used, the order of the spray coating device 41 and the curtain coating device 42 can be changed depending on the purpose. In FIG. 1a, the spray coating device 41 and the curtain coating device 42 are shown only on one side of the primary prepreg 1c. be.

Next, with reference to FIG. 1b, the outline of the second manufacturing method of the present invention, in which the modifier is applied before the matrix resin is applied, will be described. FIG. 1b is a schematic sectional view showing a prepreg manufacturing method when using a UD base material as a reinforcing fiber sheet according to one embodiment of the second manufacturing method of the present invention. The coating device 100 is provided between a transport roll 13 and a transport roll 14, which are running mechanisms for running the reinforcing fiber sheet 1a substantially downward in the vertical direction Z, and stores the matrix resin 2, which is the coating mechanism. A coating unit 20 is provided. In addition, before and after the coating device 100, a plurality of creels 11 for unwinding the reinforcing fibers 1 and a reinforcing fiber sheet 1a (in FIG. arranging device 12 for obtaining a prepreg 1d arrangement), a modifier application device 28 for obtaining a reinforcing fiber sheet 1b to which a modifier is applied, and a winding device 15 for the prepreg 1d (not shown). However, the coating device 100 is equipped with a matrix resin supply device. Furthermore, a release sheet supplying device 16 for supplying the release sheet 3 can be provided as required.

Further, when using a reinforcing fiber fabric as the reinforcing fiber sheet, an unwinding device for unwinding the reinforcing fiber fabric instead of the creel 11 in FIGS. A prepreg in which a reinforcing fiber fabric is impregnated with a matrix resin can be produced.

In FIGS. 1a and 1b, the direction in which the reinforcing fiber sheet is passed through the application section is shown as an example of vertically downward, but this direction may be a horizontal direction, or a direction inclined from the horizontal plane. There may be. When passing in the horizontal direction, it does not necessarily have to be strictly horizontal, and can be selected within a range of ±5° from the horizontal plane.

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

As a reinforcing fiber sheet, a unidirectional material (UD base material) in which a plurality of reinforcing fibers are arranged in one direction on a surface, or a reinforcing fiber sheet in which reinforcing fibers are arranged in a multiaxial manner or randomly arranged. fabric.

A known method can be used for forming the UD substrate, and there is no particular limitation, but a reinforcing fiber bundle is formed by arranging single fibers in advance, and this reinforcing fiber bundle is further arranged to form a reinforcing fiber sheet. Formation is preferable from the viewpoint of process efficiency and uniform arrangement. For example, in the case of carbon fiber, a "tow", which is a tape-shaped reinforcing fiber bundle, is wound around a bobbin, and a reinforcing fiber sheet can be obtained by arranging the tape-shaped reinforcing fiber bundles pulled out from the bobbin. Further, it has a reinforcing fiber arranging mechanism for orderly arranging the reinforcing fiber bundles pulled out from the bobbin on the creel, eliminating undesirable overlapping and folding of the reinforcing fiber bundles in the reinforcing fiber sheet, and eliminating gaps between the reinforcing fiber bundles. is preferred. As the reinforcing fiber arranging mechanism, a known roller or comb arranging device can be used. Also, stacking a plurality of reinforcing fiber sheets arranged in advance is useful from the viewpoint of reducing the gaps between the reinforcing fibers. In addition, it is preferable that the creel is provided with a tension control mechanism when pulling out the reinforcing fibers. As the tension control mechanism, a known one can be used, and a brake mechanism or the like can be used. The tension can also be controlled by adjusting the thread guide.

On the other hand, specific examples of reinforcing fiber fabrics include woven and knitted fabrics, as well as those in which reinforcing fibers are arranged two-dimensionally and multiaxially, and those in which reinforcing fibers are randomly oriented, such as nonwoven fabrics, mats, and paper. . In this case, the reinforcing fibers can be formed into a sheet by applying a binder, entangling, welding, or fusing. As the woven fabric, non-crimp woven fabric, bias structure, leno weave, multiaxial woven fabric, multiple woven fabric, etc. can be used in addition to plain weave, twill and satin basic weave structures. A fabric that combines a bias structure and a UD base material not only suppresses deformation of the fabric due to tension in the coating and impregnation processes due to the UD structure, but also has pseudo-isotropy due to the bias structure, which is a preferable form. . In addition, the multi-layered fabric has the advantage that the upper or lower surface of the fabric and the structure and characteristics of the inner part of the fabric can be individually designed. Considering the shape stability in the coating and impregnation steps, warp knitting is preferable for knitted fabrics, but a braid, which is a tubular knitted fabric, can also be used.

Among these, when giving priority to the mechanical properties of FRP, it is preferable to use a UD base material, and the UD base material can be produced by a known method of arranging reinforcing fibers in a sheet in one direction. .

<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 coating amount at the coating portion. For this reason, it is preferable to guide the reinforcing fiber sheet to the liquid pool after smoothing it. The smoothing treatment method is not particularly limited, but examples include a method of physically pressing with a counter roll or the like, a method of moving reinforcing fibers using an air current, and the like. The physical pressing method is preferable because it is simple and less likely to disturb the arrangement of the reinforcing fibers. More specifically, calendering or the like can be used. The method using an air stream is preferable because it not only causes less abrasion but also has the effect of widening the reinforcing fiber sheet.

<Expansion of reinforcing fiber sheet>
Further, in the present invention, it is also preferable from the viewpoint of efficiently producing a thin prepreg that the reinforcing fiber sheet is led to the liquid pool after being widened. The widening treatment method is not particularly limited, but examples include a method of imparting mechanical vibration and a method of spreading the reinforcing fiber bundle by 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 Japanese Patent Laid-Open No. 2015-22799, for example. As for the direction of vibration, it is preferable to apply vibration in the Y-axis direction (horizontal direction) and Z-axis direction (vertical direction) when the direction of movement of the reinforcing fiber sheet is the X axis. It is also preferable to use them in combination. Further, it is preferable to provide a plurality of projections on the surface of the vibrating roll, because the reinforcing fibers can be prevented from being rubbed by the roll. As a method using airflow, for example, SEN-I
GAKKAISHI, vol. 64, P-262-267 (2008). The methods described can be used.

<Preheating of reinforcing fiber sheet>
Further, in the present invention, preheating is preferable because the temperature drop of the matrix resin can be suppressed and the viscosity uniformity of the matrix resin can be improved by guiding the reinforcing fiber sheet to the liquid pool after heating. The reinforcing fiber sheet is preferably heated to a temperature close to the temperature of the matrix resin, and various heating means such as air heating, infrared heating, far-infrared heating, laser heating, contact heating, and heat medium heating (steam, etc.) are used for this purpose. means can be used. Among them, infrared heating is preferable because the device is simple and the reinforcing fiber sheet can be directly heated, so that even if the running speed is high, heating can be efficiently performed to a desired temperature.

<Matrix resin>
The matrix resin used in the present invention can be used as a resin composition containing various resins, particles, curing agents, and various additives described later. The prepreg obtained by the present invention is in a state in which the reinforcing fiber sheet is impregnated with the matrix resin, and can be laminated and molded as it is as a sheet-like prepreg to obtain a member made of FRP. The degree of impregnation can be controlled by designing the coating part and additional impregnation after coating. The matrix resin can be appropriately selected depending on the application, but generally thermoplastic resins and thermosetting resins are used. The matrix resin may be a molten resin melted by heating or a matrix resin at room temperature. A solution or a varnish using a solvent may also be used.

As the matrix resin, those commonly used for FRP, such as thermoplastic resins, thermosetting resins, and photocurable resins, can be used. If these are liquids at room temperature, they may be used as they are. may be dissolved in a solution or varnish for use.

The thermoplastic resin has a main chain selected from carbon-carbon bonds, amide bonds, imide bonds, ester bonds, ether bonds, carbonate bonds, urethane bonds, urea bonds, thioether bonds, sulfone bonds, imidazole bonds, and carbonyl bonds. Polymers with bonds can be used. Specifically, polyacrylate, polyolefin, polyamide (PA), aramid, polyester, polycarbonate (PC), polyphenylene sulfide (PPS), polybenzimidazole (PBI), polyimide (PI), polyetherimide (PEI), polysulfone (PSU), polyethersulfone (PES), polyetherketone (PEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyaryletherketone (PAEK), polyamideimide (PAI), etc. can. PPS, PES, PI, PEI, PSU, PEEK, PEKK, PEAK and the like are suitable for fields such as aircraft applications where heat resistance is required. On the other hand, for industrial applications and automotive applications, polyolefins such as polypropylene (PP), PA, polyester, PPS, etc. are suitable in order to increase molding efficiency. These may be polymers, or may be oligomers or monomers for low viscosity and low temperature application. Of course, depending on the purpose, these may be copolymerized, or various types may be mixed and used as polymer blends or polymer alloys.

Thermosetting resins include epoxy resins, maleimide resins, polyimide resins, acetylene-terminated resins, vinyl-terminated resins, allyl-terminated resins, nadic acid-terminated resins, and cyanate ester-terminated resins. be done. These can generally be used in combination with curing agents and curing catalysts. Moreover, it is also possible to mix and use these thermosetting resins suitably.

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. Particularly preferred are epoxy resins whose precursors are amines, phenols, and compounds having a carbon-carbon double bond. Specifically, as epoxy resins having amines as precursors, tetraglycidyldiaminodiphenylmethane, triglycidyl-p-aminophenol, triglycidyl-m-aminophenol, various isomers of triglycidylaminocresol, and phenols are used as precursors. Epoxy resins used as the body include 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, and a compound having a carbon-carbon double bond as a precursor. Examples of the epoxy resin to be used include, but are not limited to, alicyclic epoxy resins and the like. Brominated epoxy resins obtained by bromating these epoxy resins are also used. Epoxy resins whose precursors are aromatic amines represented by tetraglycidyldiaminodiphenylmethane are most suitable for the present invention because they have good heat resistance and good adhesiveness to reinforcing fibers.

A thermosetting resin is preferably used in combination with a curing agent. For example, in the case of an epoxy resin, any compound having an active group capable of reacting with an epoxy group can be used as the curing agent. Compounds having an amino group, an acid anhydride group, or an azide group are preferred. Specifically, dicyandiamide, various isomers of diaminodiphenylsulfone, and aminobenzoic acid esters are suitable. Specifically, dicyandiamide is preferably used because it is excellent in preservability of the prepreg. Further, various isomers of diaminodiphenylsulfone are most suitable for the present invention since they give a cured product having good heat resistance. As aminobenzoic acid esters, trimethylene glycol di-p-aminobenzoate and neopentyl glycol di-p-aminobenzoate are preferably used. Because it is excellent, it is selected and used according to the application. Of course, it is also possible to use a curing catalyst if necessary. In order to improve the pot life of the matrix resin, it is also possible to use a complexing agent capable of forming a complex with the curing agent or the curing catalyst.

In the present invention, it is also preferable to use a mixture of a thermoplastic resin and a thermosetting resin. Mixtures of thermosets and thermoplastics give better results than thermosets alone. This is because thermosetting resins generally have the disadvantage of being brittle but can be molded at low pressure using an autoclave, whereas thermoplastic resins generally have the advantage of being tough but are difficult to mold at low pressure using an autoclave. This is because the physical properties and moldability can be balanced by mixing and using them. When mixed and used, it is preferable that the thermosetting resin is contained in an amount of more than 50% by mass from the viewpoint of the mechanical properties of the FRP obtained by curing the prepreg.

<Inorganic particles, organic particles, polymer particles>
In addition, in the present invention, inorganic particles or organic particles can be contained in the matrix resin or the resin film described later. Although the inorganic particles are not particularly limited, for example, carbon-based particles, boron nitride particles, titanium dioxide particles, silicon dioxide particles, etc. can be suitably used in order to impart electrical conductivity, heat transfer properties, thixotropic properties, etc. Can do. The organic particles are not particularly limited, but the use of polymer particles is particularly preferable because the toughness, impact resistance, damping properties, etc. of the resulting FRP can be improved. At this time, if the glass transition temperature (Tg) or melting point (Tm) of the polymer particles is higher than the matrix resin temperature by 20° C. or more, the shape of the polymer particles can be easily maintained in the matrix resin, which is preferable. The Tg of polymer particles can be measured using a temperature-modulated DSC under the following conditions. As the temperature-modulated DSC apparatus, Q1000 manufactured by TA Instruments is suitable, and can be used after being calibrated with high-purity indium in a nitrogen atmosphere. The measurement conditions can be a temperature elevation rate of 2°C/min, a temperature modulation condition of a period of 60 seconds, and an amplitude of 1°C. The reversible component can now be separated from the resulting total heat flow and the temperature at the midpoint of the stepped signal can be taken as Tg.

Also, Tm can be measured with 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 taken as Tm.

The polymer particles are preferably insoluble in the matrix resin, and suitable polymer particles can be used by referring to, for example, WO2009/142231 pamphlet. More specifically, polyamides and polyimides can be preferably used, and polyamides are most preferred because they have excellent toughness and can greatly improve impact resistance. Examples of polyamide include polyamide 12, polyamide 11, polyamide 6, polyamide 66 and polyamide 6/12 copolymer, and semi-IPN (polymer interpenetrating network structure) with the epoxy compound described in Example 1 of JP-A-01-104624. Polyamide (semi-IPN polyamide) or the like can be preferably used. The shape of the thermoplastic resin particles may be spherical particles, non-spherical particles, or porous particles, but spherical particles are particularly preferred in the production method of the present invention because they do not reduce the fluidity of the resin. In addition, if the shape is spherical, there is no starting point for stress concentration, which is a preferable aspect in terms of providing high impact resistance.

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

Further, in order to increase the toughness of the resin layer between reinforcing fibers of FRP, it is preferable to retain the polymer particles in the resin layer between reinforcing fibers. Therefore, the number average particle diameter of the polymer particles is preferably in the range of 5 to 50 μm, more preferably in the range of 7 to 40 μm, 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 reinforcing fiber bundle and can remain in the reinforcing fiber interlayer resin layer of the resulting fiber-reinforced composite material. By setting the number average particle diameter to 50 μm or less, the thickness of the matrix resin layer on the surface of the prepreg can be optimized, and the fiber mass content in the resulting FRP can be optimized.

<Viscosity of matrix resin>
As the matrix resin used in the present invention, it is preferable to select an optimum viscosity from the viewpoint of processability and stability. Specifically, a viscosity in the range of 1 to 60 Pa·s is preferable because dripping at the outlet of the narrowed portion can be suppressed and the high-speed running performance and stable running performance of the reinforcing fiber sheet can be improved. Here, the viscosity is measured at a strain rate of 3.14 s ⁻¹ and at the matrix resin temperature at the liquid reservoir. As a measuring device, a viscoelasticity measuring device such as a parallel disk type or a cone type can be used. The viscosity of the matrix resin is more preferably 10-30 Pa·s.

<Process of applying matrix resin>
Taking the UD base material as an example, the process of applying the matrix resin will be described with reference to FIG. After the reinforcing fiber sheet 1a is obtained by arranging the reinforcing fibers 1 in one direction (the depth direction of the paper surface) by the arranging device 12, the reinforcing fiber sheet 1a is passed through the coating section 20, and on both sides of the reinforcing fiber sheet 1a A matrix resin 2 is provided. Thereby, the primary prepreg 1c can be obtained. In addition, in the second manufacturing method of the present invention, the modifier is applied before the reinforcing fiber sheet 1a is introduced into the coating section 20. As shown in FIG.

Next, the step of applying the matrix resin 2 to the reinforcing fiber sheet 1a or the reinforcing fiber sheet 1b to which the modifier has been applied will be described in detail with reference to FIGS. Since this is a step common to the first manufacturing method and the second manufacturing method, the first manufacturing method will be described as an example. FIG. 2 is an enlarged detailed cross-sectional view of the application portion 20 in FIG. 1a. The application unit 20 includes wall surface members 21a and 21b that are opposed to each other with a predetermined gap D therebetween. Between the wall surface members 21a and 21b, the cross-sectional area is continuous in the vertical direction downward Z (that is, the running direction of the reinforcing fiber sheet). and a liquid pooling portion 22 which decreases exponentially, and which is positioned below the liquid pooling portion 22 (on the carrying-out side of the reinforcing fiber sheet 1a) and is smaller than the cross-sectional area of the upper surface of the liquid pooling portion 22 (on the introduction side of the reinforcing fiber sheet 1a). 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 runs vertically downward Z while accompanying the matrix resin 2 around it. At this time, since the cross-sectional area of the liquid pool 22 decreases in the vertical direction downward Z (the running direction of the reinforcing fiber sheet 1a), the accompanying matrix resin 2 is gradually compressed and moves toward the bottom of the liquid pool 22. The pressure of the matrix resin 2 increases accordingly. When the pressure at the bottom of the liquid pool 22 increases, the accompanying liquid flow becomes difficult to flow further downward, flows in the direction of the wall surface members 21a and 21b, and then flows upward while being blocked by the wall surface members 21a and 21b. become. As a result, a circulating flow T is formed along the plane of the reinforcing fiber sheet 1a and the walls of the wall members 21a and 21b in the liquid reservoir 22. As shown in FIG. As a result, even if the sheet-like reinforcing fiber 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 constricted section 23 where the liquid pressure is high. . Further, as described below, the air bubbles adhere to the fluff, causing the fluff to move upward from the circulating flow T and pass near the upper liquid surface of the liquid pool 22 . Therefore, it is possible not only to prevent fluff from clogging the lower portion of the liquid pool portion 22 and the constricted portion 23 but also to easily collect the stagnant fluff from the upper liquid surface of the liquid pool portion 22 . Furthermore, when the reinforcing fiber sheet 1a is run at a high speed, the hydraulic pressure is further increased, so that the fluff removal effect is further enhanced. As a result, it becomes possible to apply the matrix resin 2 to the reinforcing fiber sheet 1a at a high speed, thereby greatly improving productivity.

Moreover, the increased hydraulic pressure has the effect of facilitating impregnation of the matrix resin 2 into the inside of the reinforcing fiber sheet 1a. This is based on the property (Darcy's law) that when a porous body such as a reinforcing fiber bundle is impregnated with a matrix resin, the degree of impregnation increases with the pressure of the matrix resin. Also in this case, when the reinforcing fiber sheet 1a is run at a higher speed, the hydraulic pressure increases, so that the impregnation effect can be further enhanced. The matrix resin 2 is impregnated with the air bubbles remaining inside the reinforcing fiber sheet 1a by gas/liquid substitution, but the air bubbles pass through the gaps inside the reinforcing fiber sheet 1a due to the liquid pressure and buoyancy, and are transferred to the fibers. It is discharged in the orientation direction (vertically upward). At this time, since the air bubbles are discharged without pushing away the impregnated matrix resin 2, there is an effect that the impregnation is not hindered. Some of the air bubbles are discharged from the surface of the reinforcing fiber sheet 1a in the out-of-plane direction (normal direction). There is also an effect that air bubbles are efficiently discharged without remaining in the lower portion of the liquid pool portion 22, which is highly effective. These effects allow the reinforcing fiber sheet 1a to be efficiently impregnated with the matrix resin 2, and as a result, a high-quality primary prepreg 1c uniformly impregnated with the matrix resin 2 can be obtained.

Furthermore, the increased hydraulic pressure automatically aligns the reinforcing fiber sheet 1a with the center of the gap D, preventing the reinforcing fiber sheet 1a from directly rubbing against the walls of the liquid reservoir 22 and 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 a disturbance or the like, the matrix resin 2 is pushed into the narrower gap on the approaching side and is compressed, so the hydraulic pressure on the approaching side increases more. and pushes the reinforcing fiber sheet 1a back to the center of the gap D.

The constricted portion 23 is designed to have a smaller cross-sectional area than the upper surface of the liquid pool portion 22 . As can be understood from FIGS. 2 and 4, the cross-sectional area is reduced because the length of the pseudo plane perpendicular to the reinforcing fiber sheet is small, that is, the interval between members is narrowed. This is because the impregnation and self-aligning effects can be obtained by increasing the hydraulic pressure at the constricted portion as described above. From the viewpoint of the running performance of the reinforcing fiber sheet 1a and the flow control of the matrix resin 2, the cross-sectional shape of the uppermost surface of the constricted portion 23 should match the cross-sectional shape of the lowermost surface of the liquid pool portion 22. Although preferred, the constriction 23 may be slightly larger if desired.

Here, in the application section 20 of FIG. 2, the reinforcing fiber sheet 1a runs completely downward in the vertical direction (90 degrees from the horizontal plane). It is sufficient that the reinforcing fiber sheet 1a is substantially vertically downward within a range in which the reinforcing fiber sheet 1a can stably and continuously travel.

In addition, the total amount of the matrix resin 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 matrix resin 2 applied to the reinforcing fiber sheet 1a ), the wall surface members 21a and 21b may be installed so that the gap D is widened.

FIG. 3 is a bottom view of the application unit 20 as seen from the direction A in FIG. Side wall members 24a and 24b for preventing leakage of the matrix resin 2 from both ends in the arrangement direction of the reinforcing fiber sheet 1a are provided in the application section 20, and are surrounded by the wall members 21a and 21b and the side wall members 24a and 24b. An outlet 25 of the constricted portion 23 is formed in the space. Here, the outlet 25 has a slit shape, and the cross-sectional aspect ratio (Y/D in FIG. 3) may be set according to the shape of the reinforcing fiber sheet 1a to which the matrix resin 2 is to be applied.

FIG. 4a is a cross-sectional view illustrating the internal structure of the coating section 20 when viewed from direction B. FIG. In order to make the drawing easier to see, the wall member 21b is omitted, and in the reinforcing fiber sheet 1a, the reinforcing fibers 1 are drawn as if they are arranged with a gap, but actually the reinforcing fibers 1 are arranged. It is preferable to arrange without gaps from the viewpoint of the quality of the sheet-like prepreg and the mechanical properties of the FRP.

FIG. 4b shows the flow of matrix resin 2 in gap 26. FIG. If the gap 26 is large, a vortex flow is generated in the R direction in the matrix resin 2 . Since this vortex flow R becomes a flow (Ra) directed to the outside at the lower portion of the liquid pool portion 22, it may tear the reinforcing fiber sheet (cracking of the sheet-like fiber bundle) or reduce the spacing between the reinforcing fibers. As a result, when the prepreg is made into a prepreg, there is a possibility that the reinforcing fibers are arranged unevenly. On the other hand, in the upper part of the liquid pool 22, since the flow (Rb) is directed inward, the reinforcing fiber sheet 1a is compressed in the width direction, and the ends thereof may be broken. In an apparatus for applying a matrix resin on both sides of an integrated sheet-like base material (especially a film), as typified by Patent Document 2 (Japanese Patent No. 3252278), such a vortex flow occurs in the gap 26. However, due to the small impact on quality, no attention was paid to it.

Therefore, in the present invention, it is preferable to restrict the width of the gap 26 so as to suppress the generation of eddy currents at the ends. Specifically, the width L of the liquid pool portion 22, that is, the interval L between the side plate members 24a and 24b can be configured to satisfy the following relationship with the width W of the primary prepreg measured directly below the constricted portion 23. preferable.
L≦W+10 (mm)
As a result, generation of eddy currents at the ends is suppressed, cracking and edge folding of the reinforcing fiber sheet 1a can be suppressed, and the reinforcing fibers 1 are uniformly arranged over the entire width (W) of the primary prepreg 1c, resulting in a high quality prepreg. A highly stable primary prepreg 1c can be obtained. Furthermore, when this technique is applied to prepreg, it is possible not only to improve the grade and quality of prepreg, but also to improve the mechanical properties and quality of FRP obtained by using this. If the relationship between L and W is more preferably L≦W+2 (mm), cracking and edge folding of the reinforcing fiber sheet can be further suppressed.

Also, it is preferable to adjust the lower limit of L to W-5 (mm) or more from the viewpoint of improving the uniformity of the width direction dimension of the primary prepreg 1c.

From the viewpoint of suppressing the generation of vortex flow R due to high liquid pressure in the lower portion of the liquid pool portion 22, it is preferable to perform this width regulation at least at the lower portion of the liquid pool portion 22 (position G in FIG. 4a). Furthermore, more preferably, this width regulation is performed over the entire liquid pool portion 22, so that the generation of the eddy flow R can be almost completely suppressed, and as a result, the reinforcing fiber sheet is almost completely prevented from cracking and edge folding. can be suppressed to

Further, the width regulation may be applied only to the liquid pool portion 22 from the viewpoint of suppressing the swirl flow in the gap 26. However, if the narrowed portion 23 is also subjected to the width regulation, excessive matrix resin 2 is applied to the side surface of the primary prepreg 1c. It is preferable from the viewpoint of suppressing that it is done.

<Width regulation mechanism>
Although the side wall members 24a and 24b are responsible for width regulation in the above description, width regulation mechanisms 27a and 27b may be provided between the side wall members 24a and 24b as shown in FIG. can. This is preferable from the viewpoint of being able to freely change the width regulated by the width regulating mechanism, thereby making it possible to manufacture prepregs of various widths using a single coating section. Here, the relationship between the width (W) of the reinforcing fiber sheet immediately below the constricted portion 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). Also, the lower limit of L2 is preferably adjusted to W-5 (mm) or more, preferably W (mm) or more, from the viewpoint of improving the uniformity of the widthwise dimension of the prepreg 1b. The shape and material of the width regulating mechanism are not particularly limited, but a plate-shaped bush is convenient and preferable. In addition, at the upper portion, that is, at a location near the liquid surface, the width (see FIG. 5. Refers to the length in the vertical direction of the width regulating mechanism in the "view from the Z direction") that is smaller than the interval between the wall surface members 21a and 21b. By having it, it is possible not to hinder the horizontal flow of the matrix resin, which is preferable. On the other hand, from the middle part to the lower part of the width regulating mechanism, it is preferable to have a shape that follows the internal shape of the application part because it is possible to suppress retention of the matrix resin in the liquid pool part and to suppress deterioration of the matrix resin. From this point of view, it is preferable that the width regulating mechanism is inserted up to the constricted portion 23 . FIG. 5 shows an example of a plate-shaped bush as the width regulating mechanism, and shows an example in which the lower portion of the bush is inserted along the tapered shape of the liquid pool portion 22 to the constricted portion 23 . Although FIG. 5 shows an example in which L2 is constant from the liquid surface to the outlet, the width to be regulated may be changed depending on the part within the range of achieving the purpose of the width regulating mechanism. The width regulating mechanism can be fixed to the application part 20 by any method, but in the case of a plate-shaped bush, by fixing it at a plurality of parts in the vertical direction, the restriction due to deformation of the plate-shaped bush due to high hydraulic pressure can be achieved. Width variation can be suppressed. For example, it is preferable to use a stay for the upper part and insert the lower part into the application part, because the width is easily regulated by the width regulating mechanism.

<Shape of Liquid Reservoir>
As described in detail above, in the present invention, the cross-sectional area of the liquid reservoir 22 continuously decreases in the running direction of the reinforcing fiber sheet, so that the liquid pressure can be increased in the running direction of the reinforcing fiber sheet. It is important to note that the continuous decrease in the cross-sectional area in the running direction of the reinforcing fiber sheet means that the shape 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, it may be tapered (straight) or curved such as a trumpet. Further, the cross-sectional area reduction 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 where the cross-sectional area expands as long as the objects and effects of the present invention can be obtained. You can stay. These are described in detail below with examples in FIGS.

FIG. 6 is a detailed cross-sectional view of an application portion 20b of another embodiment different from that of FIG. It is the same as the application section 20 of FIG. As in the application portion 20b of FIG. 6, the liquid pool portion 22 may be divided into a region 22a in which the cross-sectional area continuously decreases downward in the vertical direction Z 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 continuously decreases is preferably 10 mm or more. More preferably, the vertical height H at which the cross-sectional area continuously decreases is 50 mm or more. As a result, the matrix resin 2 entrained by the reinforcing fiber sheet 1a is compressed in the area 22a where the cross-sectional area of the liquid reservoir 22 continuously decreases, and the liquid generated in the lower part of the liquid reservoir 22 is secured. The pressure can be increased sufficiently. As a result, it is possible to obtain the effect of preventing fluff from clogging the narrowed portion 23 by the hydraulic pressure and impregnating the reinforcing fiber sheet 1a with the matrix resin 2 by the hydraulic pressure. In addition, when the reinforcing fiber sheet passes through the application portion in the horizontal direction or the inclined direction, the “vertical direction” is read as the “horizontal direction” or the “inclined direction”, and the “height” is the “liquid pooling portion”. distance from the outlet (that is, the interface between the liquid pool and the constriction)".

Here, when the region 22a where the cross-sectional area of the liquid pooling portion 22 continuously decreases is tapered like the coating portion 20 in FIG. 2 or the coating portion 20b in FIG. is preferable, and specifically, an acute angle (90° or less) is preferable. As a result, the effect of compressing the matrix resin 2 is enhanced in the region 22a (tapered portion) where the cross-sectional area of the liquid reservoir portion 22 continuously decreases, making it easier to obtain a high liquid pressure.

FIG. 7 is a detailed cross-sectional view of the application portion 20c of another embodiment different from that of FIG. It is the same as the application section 20b in FIG. 6 except that the wall surface members 21e and 21f forming the liquid pool section 22 are tapered in two stages. In this manner, the region 22a in which the cross-sectional area of the liquid pooling portion 22 continuously decreases may be configured with a multi-step taper portion having two or more steps. 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 pooling portion 22 continuously decreases is 10 mm or more. More preferably, the vertical height H at which the cross-sectional area continuously decreases is 50 mm or more. As shown in FIG. 7, a region 22a in which the cross-sectional area of the liquid reservoir 22 continuously decreases is formed into a multi-step tapered portion. can be made smaller. As a result, the liquid pressure generated in the lower portion of the liquid pool portion 22 becomes higher, and the effect of removing fluff and the effect of impregnating the matrix resin 2 can be further enhanced.

FIG. 8 is a detailed cross-sectional view of an application portion 20d of another embodiment different from that of FIG. 6 except that wall surface members 21g and 21h forming the liquid reservoir 22 are stepped. Thus, if there is a region 22a in which the cross-sectional area continuously decreases at the lowermost portion of the liquid pool portion 22, the effect of increasing the liquid 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 pooling portion 22 into the shape shown in FIG. 8, the depth B of the liquid pooling portion 22 can be expanded and the matrix resin 2 can be stored while maintaining the shape of the region 22a in which the cross-sectional area continuously decreases. Volume can be increased. As a result, even if the matrix resin 2 cannot be continuously supplied to the application portion 20d, the matrix resin 2 can be continuously applied to the reinforcing fiber sheet 1a for a long period of time, further improving the productivity of the prepreg.

FIG. 9 is a detailed cross-sectional view of an application portion 20e of another embodiment different from that of FIG. It is the same as the application section 20b in FIG. 6 except that the wall surface members 21i and 21j forming the liquid pool section 22 are shaped like trumpet (curved). In the application portion 20b of FIG. 6, the region 22a in which the cross-sectional area of the liquid pool portion 22 continuously decreases is tapered (straight), but is not limited thereto, and for example, has a trumpet shape (curved shape) as shown in FIG. It's okay. However, it is preferable that the lower portion of the liquid pool portion 22 and the upper portion of the constricted portion 23 are smoothly connected. This is because if there is a step at the boundary between the lower portion of the liquid pool portion 22 and the upper portion of the constricted portion 23, the reinforcing fiber sheet 1a may be caught by the step and fluff may be generated at this portion. Further, when the region where the cross-sectional area of the liquid pooling portion 22 continuously decreases is formed into a trumpet shape, the imaginary tangent line at the lowermost portion of the region 22a where the cross-sectional area of the liquid pooling portion 22 continuously decreases diverges. It is preferable to make the angle θ acute.

In the above description, an example in which the cross-sectional area decreases smoothly has been described, but the cross-sectional area of the liquid reservoir does not necessarily decrease smoothly in the present invention as long as the object of the present invention is not lost.

FIG. 10 is a detailed cross-sectional view of the application section 30 of another embodiment of the present invention. Unlike the embodiment of the present invention, the liquid reservoir 32 in FIG. It is a configuration that reduces to Therefore, the reinforcing fiber sheet 1a is easily clogged.

Further, it is possible to improve the impregnation effect by bringing the reinforcing fiber sheet into contact with a plurality of bars in the application section. FIG. 11 shows an example using three bars (35a, 35b and 35c). can be improved. In the example of FIG. 11, the impregnation rate can be made 90% or more. It should be noted that a plurality of types of means for improving the impregnation effect may be used in combination.

<Spray application process>
Next, the step of spray coating after forming the primary prepreg, which is used in the first manufacturing method, will be described in detail. In the second production method, spray coating can be used as a means for applying the modifier, but in this case, the modifier is applied onto the reinforcing fiber sheet. The spray coating process referred to in the present invention refers to a process of discharging a liquid from a discharge portion, guiding the discharged liquid by air currents or electric lines of force, and collecting the discharged liquid on a continuously conveyed sheet. Say things. Examples of the method using airflow include melt blowing and spunbonding. These methods are described, for example, in "Latest Spinning Technology", Textile Society, Kobunshi Publishing, pp. 123-127 (meltblown method), pp. 118-123 (spunbond method), (1992). . In this coating method, the equipment is relatively simple. Moreover, as a method using electric lines of force, an electrospinning method and an electrospray method can be mentioned. These methods are described, for example, in "Nanofiber Technology", CMC Publishing, pp. 113-118. In this coating method, the direction of coating is determined by the lines of electric force. There is a degree of freedom in setting up (bottom, horizontal, bottom to top, etc.).

If the liquid to be discharged is solid at room temperature, it can be melted by heating or dissolved in a solvent to be liquefied. Moreover, even if it is a liquid at room temperature, it is possible to dilute it by adding a solvent. Further, the liquid may contain solids such as inorganic particles, organic particles, and polymer particles.

The spray coating method using airflow will be described in detail below.

In this spray coating method, it is preferable that the nozzle holes are arranged in one or several rows in the width direction, and a heated air current is applied near the location where the liquid is to be discharged, as in the melt blow method. At this time, as shown in FIG. 12, it is preferable from the viewpoint of coating stability to apply air currents 44 from the front and back of the rows of die holes arranged in the width direction. Further, by adjusting the temperature, flow rate, flow velocity and direction of the airflow, it is possible to control the spinnability and cooling of the discharged liquid and its solidified material 46 . The meltblowing method is usually used for the production of short fiber nonwoven fabrics of thermoplastic resin, in which a low-viscosity resin is exposed to high-speed air currents to blow off the resin extruded from the nozzle holes to form short fibers. The fiber diameter of the resin fibers obtained here varies greatly from 1 μm to several tens of μm. In the present invention, from the viewpoint of improving the uniformity of the basis weight of the resin, it is preferable to reduce the variation in fiber diameter as much as possible, and to use continuous fibers instead of short fibers, that is, long fibers. The production conditions for the meltblown method, which is used for ordinary polyester nonwoven fabrics, are set so that the viscosity of the resin is extremely low and the velocity of the air accompanying the extruded polymer is set high in order to obtain ultrafine fibers. However, in the present invention, the ejection conditions and accompanying air velocity are adjusted for the purpose of uniformly applying the liquid and its solidified substance 46 onto the primary prepreg 1b. From this point of view, it is preferable that the viscosity of the liquid in the spray coating device is 1 to 60 Pa·s. A value measured at a strain rate of 3.14 sec ⁻¹ can be used as the viscosity of the liquid. On the other hand, the air velocity can be determined while observing the fiberization state of the discharged liquid 19 .

Whether or not the discharged liquid and its solidified substance 46 are fibrous is determined, for example, by the route of the fibrous liquid and its solidified substance 46 reaching the primary prepreg 1c from the spray coating device 41. It can be determined by observing the movement of (spinning lines) photographed with a high-speed video camera. In the case of continuous fibers, the movement of the fibrous liquid and its solidified substance 46 is observed to be linked and oscillating upstream and downstream of the spinning line. Further, when observing the solidified substance of the liquid collected on the primary prepreg 1c, it can be determined that the prepreg 1c is in the form of a continuous fiber nonwoven fabric. Also, in the case of short fibers, it can be judged that the solidified liquid collected on the primary prepreg 1c is observed, and if it is in the form of a short fiber nonwoven fabric, it is fiberized. In the present invention, the fiber length of the solidified liquid collected and shaped into fibrous form is preferably 1 cm or more, more preferably 10 cm or more, and further preferably continuous fibers. On the other hand, as described above, when the liquid is not formed into continuous fibers and is scattered as droplets, the liquid and its solidified substance collected on the primary prepreg 1c become droplets. Also, even when observed with the above-described high-speed video camera, it is difficult to observe that the upstream and downstream of the spinning line are moving in a linked manner.

In the present invention, when the discharged liquid and its solidified material are shaped into fibers and collected on the primary prepreg, unevenness in basis weight of the liquid and its solidified material can be suppressed, and the quality of the prepreg can be improved. preferable. There is also the advantage that the surroundings of the apparatus can be less contaminated with liquids and their solidified substances. When the ejected liquid or its solidified substance becomes droplets, especially in the case of micro droplets with a droplet size of several μm to several hundred μm, the droplet mass is small and the droplets are easily scattered. Unlike the case of (1), there is no mechanism for stopping the scattering of droplets.

In the present invention, when the liquid is heated, after being discharged, the liquid is cooled toward the primary prepreg, increasing its viscosity and rigidity. In particular, in the case of making continuous fibers, when the viscosity and rigidity increase due to cooling, the path of the liquid shaped into fibers and its solidified material reaching the primary prepreg is greatly affected by the air flow. become. In FIG. 13, if the height h (corresponding to the spinning length, hereinafter referred to as the coating height) from the primary prepreg 1b to the lower surface (or nozzle) of the spray coating device 41, which is the liquid discharge portion, is low, the prepreg will be fibrously applied. The shaped liquid and its solidified material 46 reach the primary prepreg 1c in a state of low viscosity and low rigidity, and the arrival route of the liquid shaped into fibers by the air flow and its solidified material 46 (equivalent to the spinning line) is less likely to be affected by the fibrous liquid and its solidified material 46, which is less likely to intersect or entangle in the middle of the spinning line, or to flow horizontally on the primary prepreg 1c. becomes linear. Therefore, the intervals between the fibrous liquid and its solidified material 46 become substantially equal, and the uniformity of basis weight of the liquid and its solidified material 46 in the width direction is improved. On the other hand, when the coating height h is high as shown in FIG. 14, the liquid formed into fibrous form before reaching the primary prepreg 1c and its solidified material 46 become highly viscous and highly rigid. In some cases, the fibrous liquid and its solidified material 46 are crossed and entangled in the middle of the spinning line, and the liquid tends to flow horizontally on the primary prepreg 1c. Therefore, it is preferable to set the coating height h to 1 to 100 mm because the uniformity of the basis weight of the resin is improved. More preferably, it is 70 mm or less. On the other hand, when the coating height h is 25 mm or more, turbulence of the air current on the primary prepreg 1b is suppressed, so droplets of the liquid and its solidified material 46 and scattering of fibers are suppressed, and the vicinity of the coating process is suppressed. Resin contamination can be suppressed, which is more preferable.

Further, when the ejected liquid is fibrillated, particularly continuous filamentized, scattering due to air currents is suppressed, and contamination of the liquid and its solidified substances in the vicinity of the coating process can be suppressed, which is preferable.

Further, as described above, the ejected fiber-shaped liquid and its solidified material are less likely to be affected by the air flow if they can maintain low viscosity and/or low rigidity even downstream of the spinning line. Therefore, in some cases, the cooling rate of the fibrous liquid and its solidified material can be controlled according to the amount of the liquid and its solidified material and the specific surface area of the fiber, so that the effect of the air flow can be reduced. Therefore, it is possible to adjust the single-hole ejection amount and the single-hole ejection area of the liquid. In addition, even if the viscosity is lowered by using a low-viscosity liquid or raising the temperature of the liquid to be ejected, it may be possible to reduce the influence of the air current. Since there is a limit to the upper limit of the resin temperature that can be applied to a thermosetting resin as a liquid, it is also effective to adjust the single hole discharge amount and the single hole discharge area as described above when the resin viscosity is high. In addition, since the cooling and thinning process of the fibrous resin can also be adjusted by the temperature, flow rate, and flow velocity of the airflow acting on the discharged resin, these process parameters can be appropriately combined. The velocity and flow rate of the airflow may be adjusted by the pressure of the supplied air in industrial production equipment.

In addition, in the present invention, when the discharged liquid and its solidified substance are collected in the region where the primary prepreg is conveyed in a substantially flat shape, the reinforcing fiber sheet curves downward as described in Patent Document 5. Various problems caused by this can be solved. Here, the region in which the primary prepreg 1c is substantially linearly conveyed in the longitudinal direction near the collection portion of the liquid and its solidified material 46 as shown in FIG. It refers to the area that is conveyed in a shape. This is because, in FIG. 12, the primary prepreg 1c conveyed in the vicinity of the collecting portion of the liquid and its solidified substance 46 appears substantially linear when viewed from the horizontal arrangement direction of the reinforcing fibers, that is, from the front side to the back side. means that In the present invention, there is no particular limitation on the specific method for preventing the primary prepreg from bending downward even if there is a downward air flow in the spray coating process. In the process, it is effective to place an object (a table 45 is illustrated in FIG. 12) that can support the primary prepreg 1c under the primary prepreg 1c. In addition, it is preferable to convey the primary prepreg with an appropriate tension from the viewpoint of maintaining the alignment of the reinforcing fibers.

<Curtain coating process>
Next, the curtain coating process after forming the primary prepreg will be described in detail. Here, the term "curtain coating" means that a liquid is discharged in a plane, and a film-like substance is formed in the discharged space and applied. Also good. Therefore, since the present invention employs non-contact coating, it is possible to solve various problems caused by rubbing, as compared with the method of pressing the coating head. In the second production method, curtain coating can be used as means for applying the modifier, but in this case, the modifier is applied onto the reinforcing fiber sheet.

Next, in the present invention, it is preferable that the angle formed by the direction of liquid ejection and the direction of transport of the primary prepreg (this angle may be referred to as a "coating angle" for convenience) is 80° or less. FIG. 15 shows a general coating method when the transport direction of the primary prepreg 1c is horizontal, but the angle formed by the liquid ejection direction and the transport direction of the primary prepreg 1c is 90°. . When the present inventors conducted an experiment using a thermosetting resin (epoxy resin, etc.), it was found that when the angle formed by the direction of liquid ejection and the direction of transport of the primary prepreg was 90°, the transport speed was increased for coating. Sometimes it was difficult to do In addition, when the coating device is pressed against the primary prepreg, the film is not formed in the air, so it is considered that such a problem does not occur. However, as shown in FIG. 16, by setting the angle between the liquid ejection direction and the transport direction of the primary prepreg 1c to 80° or less, the liquid is planarly ejected to form the film 47. The inventors of the present invention have also found that the coating can be stably performed at a high speed. A smaller application angle α is preferable because it enables stable and high-speed application. However, when the coating angle α becomes small, the size of the coating head tends to interfere with the transporting process of the primary prepreg, which may cause restrictions on the apparatus. From this point of view, the coating angle α is preferably 30 to 70°.

The coating height h, which is the distance between the center of the discharge line and the primary prepreg 1c shown in FIG. It is preferable because it can improve the property. Further, it is preferable to set the thickness to 18 mm or less because the formation of the film is stabilized.

The curtain coating device may be any device as long as it is capable of planarly discharging a liquid. More specifically, a preferred example is an apparatus capable of forming a surface or curtain-like film by ejecting liquid having a uniform thickness in the width direction from a nozzle for ejecting liquid. In general, what is called a die coater can be used, and a structure that can discharge liquid from slits having a uniform thickness without intermittence can be used. Further, the curtain coating apparatus preferably has a heating mechanism capable of heating the liquid immediately before ejection and adjusting the viscosity to an arbitrary value. In particular, when using a curable resin as a liquid, there is a risk of deterioration due to the heat history of the resin during storage, an increase in viscosity, and a runaway reaction. is preferred. The viscosity of the liquid in the curtain coating device is preferably 1 to 60 Pa·s. A value measured at a strain rate of 3.14 sec ⁻¹ can be used as the viscosity of the liquid.

Moreover, in the present invention, the film has a free surface in the space into which the liquid is discharged, so the shape of the film is easily deformed. For example, the edges of the film shrink in the width direction due to so-called "neck-in", or the entire film is pulled when the primary prepreg is conveyed at high speed, resulting in unstable film formation. or the uniformity of the basis weight of the film may be impaired. Therefore, it is preferable to stabilize the formation of the film by applying an air flow to the widthwise end of the film.

In the film, a phenomenon called "neck-in" occurs, in which the edge of the film is pulled toward the center of the film in the direction perpendicular to the direction of tension, and the width of the film is reduced (see FIG. 17, the portion indicated by N). , the width of membrane 47 is reduced). It is considered that this phenomenon is particularly likely to occur when the film is subjected to high tension, such as when the viscosity of the liquid forming the film or its solidified substance is high, or when the pulling speed is high. In particular, when the film is formed at high speed by the prepreg manufacturing method of the present invention, it is preferable to suppress neck-in. For this reason, in the present invention, an air flow (end air 48) is caused to act from the front surface of the membrane toward the ends, for example, by blowing (see FIGS. 17 and 18) to expand the ends of the membrane. preferable. The airflow for this purpose is called edge air in the present invention. A metal pipe or a nozzle can generally be used as means for applying end air. It is preferable to appropriately select the air velocity, flow rate, angle, position, and temperature of the edge air in consideration of neck-in and stable formation of the resin film. Edge air can also be used when applying a film. The time of coating means before starting to discharge the liquid from the nozzle, when starting to discharge the liquid from the nozzle, while discharging the liquid from the nozzle, while the film is formed and applied to the primary prepreg, etc. as appropriate. Can be selected and applied.

Also, as shown in FIG. 19, the film may be excessively pulled in the film pulling direction, that is, the prepreg transport direction. In this case, for example, as shown in FIG. It is preferable to blow an air current (surface air 47) toward the surface to move the position where the film 47 contacts the primary prepreg 1c closer to the curtain coating device side. The airflow for this purpose is called face air in the present invention. It is preferable to appropriately select the air velocity, flow rate, angle, position, and temperature of the face air in consideration of whether the film is stably formed. As a means for applying air to the surface, a nozzle having a slit-like or line-like arrangement of pores can be generally used. In addition, it is preferable to equip the curtain coating apparatus with the apparatus for applying both the edge air and the surface air, from the viewpoint of making the apparatus compact and handleability (see FIG. 21). As for the effect on the surface portion of the film, the position where the film contacts the primary prepreg can also be brought closer to the coating portion side by sucking air from the back side of the film.

Although the above describes the case where the primary prepreg is conveyed horizontally, as shown in FIG. 22, curtain coating can also be applied to the primary prepreg on the roll. At this time, the angle formed by the tangent line when the film 47 and the primary prepreg 1b on the roll 50 are in contact with each other and the ejection direction can be defined as the "coating angle".

<Liquid applied by spray coating or curtain coating in the first manufacturing method>
In the first production method of the present invention, the liquid applied to the primary prepreg by spray coating or curtain coating is not particularly limited and can be appropriately selected according to the purpose. For example, the matrix resin described above can be used. Thermosetting resins and thermoplastic resins can also be used alone, and curing agents and various additives can also be used alone. Furthermore, the liquid may contain solids such as inorganic particles, organic particles, and polymer particles. In addition, these materials can be adjusted to a viscosity suitable for spray coating or curtain coating by heating or adding a solvent depending on the purpose.

For example, when it is desired to impart tackiness to the prepreg surface, a substance capable of imparting tackiness, such as liquid epoxy resin, urethane resin, or rubber, can be appropriately adjusted so as to achieve the desired tackiness. Alternatively, part or all of the curing agent may be extracted from the matrix resin used to form the primary prepreg and applied again by spray coating or curtain coating. By doing so, the viscosity of the matrix resin used when forming the primary prepreg can be lowered, the process stability can be improved, and the production speed can be increased. Alternatively, some or all of the particles may be extracted from the matrix resin used to form the primary prepreg and may be applied again by spray coating or curtain coating. By doing so, the viscosity of the matrix resin used when forming the primary prepreg can be lowered, the process stability can be improved, and the production speed can be increased. At this time, the particles can be used by forming a suspension with an appropriate liquid, or by being contained in a thermosetting resin or thermoplastic resin. Moreover, by doing so, it is possible to selectively arrange the particles on the surface of the prepreg, and to selectively arrange the particles between the reinforcing fiber layers. In addition, by using a liquid that is solid at room temperature, it is possible to adjust the unevenness (roughness) of the prepreg surface, thereby improving the vacuum pressure moldability.

<Addition of modifier in second production method>
In the second manufacturing method of the present invention, a modifier is applied to the reinforcing fiber sheet 1a before being introduced into the coating section.

(Modifier)
The modifier is a general term for agents selected from the group consisting of anti-thread splitting agents, toughness improvers, flame retardants and fluff bundling agents, and is an agent capable of improving the quality and functionality of prepregs. . As for the modifier to be applied, one modifier can be selected from these groups and applied, and it is of course possible to use a plurality of modifiers in combination or to use them in combination. Each modifier will be described in detail.

(Thread crack prevention agent)
The thread splitting inhibitor is an agent that enhances the uniformity of weight in the width direction, which is an important quality of prepreg. Yarn breakage will be described with reference to FIG. 1b. When carbon fibers are used as the reinforcing fibers 1, the reinforcing fiber sheet 1a can be obtained by arranging tows. There may be cracks between the toes. This is called thread breakage. When this fiber-split reinforcing fiber sheet is passed through the matrix resin 2, the obtained prepreg 1c has no reinforcing fibers in the width direction, resulting in poor quality, and the uniformity of basis weight in the width direction may deteriorate. In particular, when the width of the portion of the prepreg 1c where there is no reinforcing fiber in the width direction with respect to the reinforcing fiber arrangement direction is 2 mm or more, the quality is determined to be poor. This thread splitting can be improved or eliminated by applying a thread splitting prevention agent to the reinforcing fiber sheet 1 a before passing through the application section 20 . The thread splitting inhibitor is a chemical agent applied so as to connect or span between tows. By applying the filament splitting inhibitor to restrict or suppress the movement of the tow in the width direction, the reinforcing fiber sheet can be substantially integrated, and as a result, filament splitting between the tows can be suppressed. . The component of the yarn splitting inhibitor to be applied is not particularly limited as long as it can suppress yarn splitting between tows. When the anti-thread splitting agent is a matrix resin 2 to be applied in the coating section 20 described later, a component contained in the matrix resin 2, or a combination of components selected from the components, the finally obtained prepreg is laminated and cured. It is preferable because the mechanical properties of the CFRP that has been treated are not significantly deteriorated. As a specific component, a mixture selected from epoxy resins, epoxy resin curing agents, and thermoplastic resins is also preferable. Excellent. As a specific example of the component of the anti-thread splitting agent to be applied, a low-viscosity resin is preferable, and the heating required for melting when applying can be omitted or simplified, and the degree of impregnation during coating or additional impregnation can be increased. can be done. The term “low viscosity” as used herein means a viscosity of 4000 Pa·s or less when measured at 40° C. and a strain rate of 3.14 s ⁻¹ . As a measuring device, a viscoelasticity measuring device such as a parallel disk type or a cone type can be used.

(Toughness improver)
The toughness improver is an agent capable of enhancing the toughness and impact resistance of CFRP obtained by laminating and curing prepregs obtained by adding the agent. By applying the toughness improving agent to the reinforcing fiber sheet before entering the matrix resin, the toughness improving component can be applied to the surface layer of the reinforcing fiber sheet, the toughness of CFRP can be increased, and further, it can be used as a thread cracking prevention agent. It is also possible to fulfill the roles simultaneously. Polyamide and polyimide are preferable as the component of the toughness improver to be imparted, and impact resistance can be enhanced due to their excellent toughness. From the viewpoint of imparting high heat resistance, the Tg is preferably 180° C. or higher, and preferably has an aromatic ring in the molecule. Specifically, polyethersulfone, polyetherethersulfone, polyetherimide, polyphenylene oxide, polysulfone, etc. are preferably used. As the toughness improver, these components can be melted and imparted, or particles can be kneaded with the resin and used.

(Flame retardant material)
A flame retardant is an agent that can improve the flame retardancy of CFRP by adding it, and is a property particularly required for structural members and building materials such as aircraft and vehicles. By applying the flame retardant to the reinforcing fiber sheet before entering the matrix resin, the flame retardant property of CFRP can be imparted by applying the flame retardant to the surface layer of the reinforcing fiber sheet. As the flame retardant used in the present invention, a resin obtained by kneading a generally known flame retardant can be used. For example, resins obtained by kneading metal hydroxides, metal oxides, phosphorus atom-containing compounds such as red phosphorus, phosphoric acid esters, and phosphates, nitrogen-containing compounds, antimony trioxide, and the like can be used.

(Fluff sizing agent)
The fluff sizing agent is an agent that, when applied, integrates the fluff protruding in the out-of-plane direction of the reinforcing fiber sheet into the reinforcing fiber sheet. If there is fluff protruding out of the plane of the reinforcing fiber sheet, the fluff may be cut off when passing through the narrowed portion of the application portion and deposited in the matrix resin retained in the application portion. By applying a fluff sizing agent to the reinforcing fiber sheet before it enters the application section, the fluff protruding from the reinforcing fiber sheet in the application section is cut at the constricted section, and the fluff stays in the matrix resin stored in the application section. In addition, it is possible to achieve the role of a thread splitting inhibitor at the same time. The component of the fluff sizing agent to be applied is not particularly limited, but the anti-fluff agent is a matrix resin 2 to be applied in the coating unit 20 described later, a component contained in the matrix resin 2, or a combination of components selected from the components. In this case, the mechanical properties of the finally obtained CFRP obtained by laminating and curing the prepreg are not greatly deteriorated, and the occurrence of fluff deposited on the coated portion can be suppressed, which is preferable. As a specific component, a mixture selected from epoxy resins, epoxy resin curing agents, and thermoplastic resins is also preferable. Excellent. As a specific example of the component of the fluff sizing agent to be applied, a low-viscosity resin is preferable, and it is possible to omit or simplify the heating required for melting when applying, or to increase the degree of impregnation during coating or additional impregnation. can. The term “low viscosity” as used herein means a viscosity of 4000 Pa·s or less when measured at 40° C. and a strain rate of 3.14 s ⁻¹ . As a measuring device, a viscoelasticity measuring device such as a parallel disk type or a cone type can be used.

(Method of applying modifier)
The method for applying the modifier is not particularly limited, and various methods can be used. A non-contact coating method with respect to the reinforcing fiber sheet is preferred because it can be suppressed. For example, spray coating (including melt blowing) and curtain coating described above can be used.

(Basket weight of modifier to be applied)
The weight per unit area of the modifying agent applied to both sides (the mass of the modifying agent applied to the reinforcing fiber sheet 1a per unit area) is preferably 20 g/m ² or less. Within this range, the process stability and the quality, grade, and functionality of the prepreg can be obtained, and the mechanical properties of the CFRP obtained by laminating and curing the finally obtained prepreg can be suppressed from significantly deteriorating.

(Longitudinal Application Interval of Modifier)
When the width of the spray application head is narrower than the width in the width direction of the reinforcing fiber sheet, the spray application head can also be traversed in the width direction. In this case, since the spray coating may form a zigzag pattern on the reinforcing fiber sheet, the modifier may be applied intermittently in the running direction of the reinforcing fiber sheet. At this time, the application interval in the longitudinal direction of the modifier (also referred to as the spray application interval when the modifier is applied by spray coating) is preferably within a maximum of 30 mm, and the effect of the modifier is within this range. easy to obtain. Note that the application interval is within a maximum of 30 mm, when the reinforcing sheet to which the modifier is applied is observed at three locations near both ends and near the center of the reinforcing fiber sheet at 100 cm (running direction) x 10 cm (width direction). It means that there is no part where the distance exceeding 30 mm in the running direction of the part to which the modifier is not applied is not present at any of the observation points. By using a wide spray coating head or using a plurality of spray coating heads, the spray coating interval can be reduced even if the running speed of the reinforcing fiber sheet is increased.

<Modifying agent application step in the second manufacturing method>
In the case of using the UD base material as the reinforcing fiber sheet, the modifying agent application step will be described with reference to FIG. 1b. A plurality of reinforcing fibers 1 unwound from a creel 11 are arranged by an arranging device 12, and the resulting reinforcing fiber sheet is linearly passed through a modifier applying device to apply a modifier, thereby obtaining a modified In this example, the reinforcing fiber sheet 1b to which the agent is applied is changed from the horizontal direction to the vertical downward direction by the transport roll 13 and passed through the coating section 20. FIG.

As the modifying agent application device, it is possible to appropriately select and use from various application devices without limitation within the scope of achieving the object of the present invention. Spray coating (including melt blowing) is preferable because it facilitates coating with a low basis weight. Furthermore, melt blowing is preferable because the modifier is led to the reinforcing fiber sheet by an air flow, so that there is little contamination around the apparatus, less loss of the modifier, and high uniformity in basis weight. The curtain cloth is preferable because the modifier can be applied without interruption.

The modifier may be applied to one side or both sides of the reinforcing fiber sheet 1a. In FIG. 1b, the place where the modifier is applied to the reinforcing fiber sheet 1a is the area where the reinforcing fiber sheet 1a obtained by the arranging device 12 is horizontally conveyed up to the conveying roll 13 that changes the direction. Although an example in which the device 28 is provided and the modifier is applied has been shown, of course, the application of the modifier is not particularly limited as long as it is between the reinforcing fiber arrangement device 12 and the coating section 20, and the coating is performed from the transport roll 13. A modifying agent application device may be provided in the section up to the part, and the modifying agent may be applied to the reinforcing fiber sheet running vertically downward. Although omitted in FIG. 1B, a reinforcing fiber sheet widening device, a smoothing device, and a reinforcing fiber sheet preheating device can be used between the creel for unwinding the reinforcing fibers and the coating section. Further, the arranging device, the widening device, the smoothing device, and the preheating device can be used by appropriately changing the order.

When a reinforcing fiber fabric is used, the creel 11 in FIG. 1b may be replaced with a reinforcing fiber fabric unwinding device, and the arranging device 12 in FIG. 1 may be replaced with a nip roll to pull out the reinforcing fiber fabric.

<Travel mechanism>
A known roller or the like can be suitably used as a traveling mechanism for conveying the reinforcing fiber sheet or the prepreg of the present invention.

In addition, in the present invention, it is preferable that the running path of the reinforcing fiber sheet is as straight as possible in order to suppress the arrangement disorder and fluffing of the reinforcing fibers. In addition, prepreg is often laminated with a release sheet to form a sheet-like integrated product, and in the process of transporting this, if it has a bent portion, wrinkles may occur due to the difference in peripheral length between the inner layer and the outer layer. Therefore, it is preferable that the running path of the sheet-like integrated object be as straight as possible. From this point of view, it is preferable to use nip rolls in the traveling path of the sheet-like integrated product.

Which of the S-shaped rolls and the nip rolls is used 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 pulling out the primary prepreg from the coating section downstream of the coating section. This is because high frictional force and shearing stress are generated between the reinforcing fiber sheet and the matrix resin at the coating part, and in order to overcome this and pull out the prepreg, it is preferable to generate high take-up tension downstream of the process. is. A nip roll, an S-shaped roll, or the like can be used as the high-tension take-up device, but by increasing the frictional force between the roll and the prepreg, slip can be prevented and stable running can be made possible. . For this purpose, it is preferable to arrange a material having a high coefficient of friction on the surface of the roll, or to increase the nip pressure or the pressing pressure of the prepreg against the S-shaped roll. From the viewpoint of preventing slippage, the S-shaped roll is preferable because the frictional force can be easily controlled by the roll diameter, contact length, and the like.

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

<Additional impregnation>
In order to adjust the degree of impregnation to a desired degree, it is possible to combine the present invention with means for further increasing the degree of impregnation using an impregnation device after coating. Here, in order to distinguish from the impregnation at the coating part, additional impregnation after coating is referred to as additional impregnation, and a device therefor is referred to as additional impregnation device. The device used as the additional impregnation device is not particularly limited, and can be appropriately selected from known devices depending on the purpose. For example, as described in JP-A-2011-132389 and WO2015/060299 pamphlet, after preheating a laminate of sheet-like carbon fiber bundles and resin with a hot plate to sufficiently soften the resin on the sheet-like carbon fiber bundles, The impregnation can be proceeded by using a pressurizing device, also with heated nip rolls. The temperature of the hot plate for preheating, the surface temperature of the nip rolls, the linear pressure of the nip rolls, and the diameter and number of the nip rolls can be appropriately selected so as to obtain a desired degree of impregnation. It is also possible to use an "S-wrap roll" in which a prepreg sheet runs in an S shape, as described in WO2010/150022 pamphlet. In the present invention, the "S-wrap roll" is simply referred to as the "S-shaped roll". WO2010/150022 pamphlet Fig. 1 describes an example in which the prepreg sheet runs in an S shape. may be adjusted. Further, when the impregnation pressure is increased to increase the degree of impregnation, it is possible to add opposing contact rolls. Furthermore, as shown in FIG. 4 of WO2015/076981 pamphlet, it is possible to improve the impregnation efficiency by arranging a conveyor belt facing the "S-wrap roll", thereby increasing the production speed of the prepreg. In addition, as described in WO2017/068159 pamphlet and Japanese Patent Application Laid-Open No. 2016-203397, the impregnation efficiency can be improved by applying ultrasonic waves to the prepreg before impregnation and rapidly raising the temperature of the prepreg. be. Further, as described in JP-A-2017-154330, it is also possible to use an impregnation device that vibrates a plurality of "squeezing blades" with an ultrasonic generator. In addition, it is also possible to impregnate the prepreg by folding it as described in Japanese Patent Application Laid-Open No. 2013-22868.

<Simple additional impregnation>
In the above, an example of applying a conventional additional impregnation device was shown, but there are cases where the temperature of the primary prepreg is still high immediately below the coating section, and in such cases, it takes a long time after leaving the coating section. If the additional impregnation operation is added at the stage where the primary prepreg is not pre-heated, it is possible to omit or simplify a heating device such as a hot plate for reheating the primary prepreg, thereby greatly simplifying and miniaturizing the impregnation device. Such an impregnating device positioned directly below the coating section is called a simple additional impregnating device. A heating nip roll or a heating S-shaped roll can be used as a simple additional impregnation device. It is preferable because not only the size can be reduced but also the power consumption can be reduced.

Further, it is preferable to apply a release sheet to the primary prepreg before the primary prepreg enters the simple additional impregnation device, because the running properties of the primary prepreg are improved.

FIG. 23 shows an example of a process equipped with a follow-up impregnation device. A simple additional impregnation device 453 is provided directly below the application unit 430 . Here, the simple additional impregnation device 453 shows an example of a nip roll, but the nip roller preferably has a heating mechanism. Also, the number of stages of the nip rolls can be appropriately selected depending on the purpose, but from the viewpoint of process simplification, three stages or less is preferable (FIG. 23 shows an example of two stages). Moreover, it is preferable that the nip rollers are provided with a driving device from the viewpoint of facilitating tension control during prepreg transport. The nip pressure can be adjusted appropriately according to the desired degree of impregnation.

In addition, it is preferable that the surface of the nip roll is subjected to an appropriate release treatment so that the primary prepreg does not stick, or that a release sheet is inserted between the primary prepreg and the nip roll (for simplification, the figure 23 is not drawn). When inserting the release sheet between the primary prepreg and the nip roll, it is preferable to insert from the coating section 430 side and separate the release sheet from the primary prepreg by the rolls on the high tension take-off device 444 side. The separated release sheet may be wound as it is, or may be run on a circuit so as to be inserted again from the application section 430 side as it is.

In addition to the nip rolls, the above-mentioned "S-wrap rolls" and fixed bars can also be used as the additional impregnation device. A non-contact heating device using infrared rays, laser, or the like can also be used.

<Prepreg>
The impregnation rate of the matrix resin in the prepreg obtained by the manufacturing method of the present invention is desirably 10% or more. The state of impregnation with the matrix resin can be checked by tearing the sampled prepreg and visually inspecting the inside, and can be evaluated more quantitatively by, for example, a peeling method. The impregnation rate of the matrix resin by the peeling method can be measured as follows. That is, the collected prepreg is sandwiched between adhesive tapes, which are peeled off to separate the reinforcing fibers to which the matrix resin is attached and the reinforcing fibers to which the matrix resin is not attached. Then, the ratio of the mass of the reinforcing fibers to which the matrix resin is adhered to the mass of the entire reinforcing fiber sheet that has been put in can be used as the impregnation rate of the matrix resin by the peeling method. Moreover, in the case of a prepreg having a high degree of impregnation, the degree of impregnation can also be evaluated based on the water absorption rate of the prepreg due to capillary action. Specifically, according to the method described in Japanese Patent Application Publication No. 2016-510077, the prepreg is cut into 10 cm × 10 cm, one side is 5 mm, and it can be calculated from the mass change when immersed in water for 5 minutes. .

In describing the present invention, the reinforcing fiber sheet impregnated with the matrix resin drawn out from the application portion is referred to as a primary prepreg, but as a term, the primary prepreg is a term belonging to the concept of prepreg. Needless to say.

<Prepreg width>
Since prepreg, which is a kind of precursor of FRP, is one form of prepreg obtained in the present invention, the case where the present invention is applied to FRP use will be described below.

The width of the prepreg is not particularly limited, and may be as wide as several tens cm to 2 m, or may be tape-like with a width of several mm to several tens mm, and the width can be selected according to the application. In recent years, devices called ATL (Automated Tape Laying) and AFP (Automated Fiber Placement), which automatically laminate narrow prepregs and prepreg tapes, have become widely used in order to improve the efficiency of the prepreg lamination process. It is also preferable to set the width to match this. ATL often uses narrow prepregs with widths of about 7.5 cm, about 15 cm, and about 30 cm, and AFPs often use prepreg tapes with a width of about 3 mm to about 25 mm.

A method for obtaining a prepreg having a desired width is not particularly limited, and a method of slitting a wide prepreg having a width of about 1 m to 2 m into narrow widths can be used. Also, in order to simplify or omit the slitting process, the width of the application portion used in the present invention can be adjusted so that the desired width is obtained from the beginning. For example, when manufacturing a narrow prepreg with a width of 30 cm for ATL, the width of the outlet of the coating section may be adjusted accordingly. In order to manufacture this efficiently, it is preferable to manufacture the product with a width of 30 cm. A line of prepregs can be manufactured. FIG. 24 shows an example in which five application units are connected in parallel. At this time, the five reinforcing fiber sheets 416 may pass through five independent reinforcing fiber preheating devices 420 and coating units 430 to obtain five primary prepregs 471. Alternatively, the five reinforcing fiber preheating The device 420 and the application section 430 may be integrated in parallel. In this case, the application section 430 may be provided with five independent width regulating mechanisms and five application section outlet widths.

In the case of prepreg tape, a reinforcing fiber sheet is formed from one to three tape-shaped reinforcing fiber bundles, and the sheet is passed through an application section whose width is adjusted so that the desired tape width can be obtained. You can also get it by In the case of prepreg tapes, there are many cases where precision in the width of the tape is particularly required from the viewpoint of controlling the overlapping of the tapes in the lateral direction. For this reason, it is preferable to control the width of the outlet of the application section more strictly. In this case, it is preferable that the aforementioned L, L2 and W satisfy the relationship of L≦W+1 mm and/or L2≦W+1 mm. .

<Slit>
There is no particular limitation on the method of slitting the prepreg, and a known slitting device can be used. After winding the prepreg once, the prepreg may be installed in a slitting device again and slitting may be performed, or for efficiency, the slitting process may be arranged continuously from the prepreg manufacturing process without once winding the prepreg. In addition, in the slitting process, a wide prepreg of 1 m or more may be directly slit to a desired width, or once cut and subdivided into narrow prepregs of about 30 cm, and then slit again to a desired width. good.

When a plurality of application portions of the narrow prepreg and prepreg tape are arranged in parallel, the release sheets may be supplied independently, or one wide release sheet may be supplied and A plurality of prepregs may be laminated. The widthwise end of the prepreg thus obtained can be cut off and supplied to an ATL or AFP apparatus. In this case, most of the cut edge becomes a release sheet, so the matrix resin component (resin component in the case of FRP) adhering to the slit cutter blade can be reduced, and the cleaning cycle of the slit cutter blade can be extended. There is also the advantage of being able to

<Modifications (Variations) and Applications of the Present Invention>
In the present invention, by using a plurality of coating units, it is possible to further improve the efficiency of the manufacturing process and improve the functionality.

For example, a plurality of coating units can be arranged so as to laminate a plurality of prepregs. FIG. 25 shows an example of a mode in which prepreg lamination is performed using two coating units. The two primary prepregs 471 pulled out from the first coating section 431 and the second coating section 432 pass through the direction change roll 445 and are laminated together with the resin film 443 on the lamination roll 447 below. Placing a release sheet between the prepreg and the direction change roll is preferable because it prevents the prepreg from sticking to the nip rolls and stabilizes running. FIG. 16 exemplifies an apparatus in which a release sheet 446 is caused to run on two direction changing rolls 445 in a circuit. It should be noted that the direction changing roll can be replaced by a direction changing guide or the like that has been subjected to mold release treatment. Although the high tension take-up device 444 is arranged after lamination of the primary prepreg 471 in FIG. 25, it can of course be arranged before lamination. Although the spray coating device and the curtain coating device are not shown in FIG. 25, they can be arranged at arbitrary positions after the primary prepreg is formed.

By using such laminated prepregs, it is possible to improve the efficiency of the prepreg laminating process, which is effective, for example, when manufacturing thick FRP. In addition, by laminating thin prepregs in multiple layers, the toughness and impact resistance of FRP can be expected to be improved, and by applying this manufacturing method, thin multilayer laminated prepregs can be obtained efficiently. Furthermore, by easily laminating different kinds of prepregs, a heterobonded prepreg with added functionality can be easily obtained. In this case, it is possible to change the type and fineness of the reinforcing fiber, the number of filaments, mechanical properties, fiber surface properties, and the like. Also, different matrix resins (resins in the case of prepreg) can be used. For example, a heterobond prepreg in which prepregs with different thicknesses or prepregs with different mechanical properties are laminated can be used. In addition, a resin with excellent mechanical properties is applied in the first application part, and a resin with excellent tackiness is applied in the second application part. Obtainable. Conversely, it is also possible to place a non-tacky resin on the surface. It is also possible to apply the particle-free resin in the first application section and apply the particle-containing resin in the second application section.

As another mode, as illustrated in FIG. 24 and described above, a plurality of application portions are arranged in parallel in the running direction of the reinforcing fiber sheet, that is, a plurality of application portions are arranged in parallel in the width direction of the reinforcing fiber sheet. can be done. This makes it possible to efficiently manufacture a narrow width or tape-shaped prepreg. Also, by changing the reinforcing fiber or the matrix resin for each coated portion, it is possible to obtain a prepreg having different properties in the width direction.

As another aspect, a plurality of application portions can be arranged in series with respect to the running direction of the reinforcing fiber sheet. FIG. 26 shows an example in which two application units are arranged in series. It is preferable to dispose a high tension take-up device 448 between the first application section 431 and the second application section 432 from the viewpoint of stabilizing the running of the reinforcing fiber sheet 416, but depending on the application conditions and the take-up conditions downstream of the process, can be omitted. In addition, if a release sheet is placed between the primary prepreg pulled out from the first coating section and the high-tension take-up device 448, sticking of the primary prepreg to the nip rolls can be suppressed, and running can be stabilized. ,preferable. FIG. 26 exemplifies a device in which the high-tension take-up device 448 is a nip roll, and the release sheet 446 is run on two rolls in a circuit.

Such a serial arrangement allows the type of matrix resin to be changed in the thickness direction of the primary prepreg. Moreover, even with the same kind of matrix resin, by changing the application conditions depending on the application part, it is possible to improve the running stability and high-speed running performance. For example, a resin with excellent mechanical properties is applied in the first application part, and a resin with excellent tackiness is applied in the second application part. Obtainable. Conversely, it is also possible to place a non-tacky resin on the surface. It is also possible to apply the particle-free resin in the first application section and apply the particle-containing resin in the second application section. Although the spray coating device and the curtain coating device are not shown in FIG. 26, they can be arranged at arbitrary positions after the primary prepreg is formed.

As described above, several modes of arranging a plurality of application parts have been shown, but the number of application parts is not particularly limited, and can be applied in various ways according to the purpose. Of course, it is also possible to combine these arrangements. Furthermore, various sizes and shapes of application portions and application conditions (temperature, etc.) can be mixed and used.

As described above, the manufacturing method of the present invention enables not only manufacturing efficiency and stability, but also high performance and functionalization of products, and is a manufacturing method excellent in expandability.

<Matrix resin supply mechanism>
In the present invention, the matrix resin is stored in the coating portion, but it is preferable to replenish the matrix resin appropriately as the coating progresses. There is no particular limitation on the mechanism for supplying the matrix resin to the application section, and a known device can be used. It is preferable to continuously supply the matrix resin to the application section, since the running of the reinforcing fiber sheet can be stabilized without disturbing the upper liquid surface of the application section. For example, it is possible to supply the matrix resin with its own weight as a driving force from a tank in which the matrix resin is stored, or to supply the matrix resin continuously using a pump or the like. As the pump, a gear pump, a tube pump, a pressure pump, or the like can be appropriately used according to the properties of the matrix resin. Moreover, when the matrix resin is solid at room temperature, it is preferable to provide a melter above the reservoir. A continuous extruder or the like can also be used. In addition, it is preferable to provide a mechanism capable of continuously supplying the matrix resin in accordance with the amount of application so that the liquid surface of the upper portion of the application portion of the matrix resin becomes as constant as possible. For this purpose, for example, a mechanism is conceivable in which the height of the liquid surface and the weight of the application portion are monitored and fed back to the supply device.

A liquid supply mechanism used for spray coating and curtain coating can also be provided like the matrix resin supply mechanism.

<Online monitoring>
Moreover, it is preferable to provide a mechanism for online monitoring of the coating amount for monitoring the coating amount. The online monitoring method is also not particularly limited, and known methods can be used. For example, a beta ray meter or the like can be used as a device for measuring thickness. In this case, the application amount can be estimated by measuring the thickness of the reinforcing fiber sheet and the thickness of the prepreg and analyzing the difference between them. The coating amount monitored online is immediately fed back to the coating section and can be used to adjust the temperature of the coating section and the gap D (see FIG. 2) of the constricted section 23 . Coating amount monitoring can of course also be used as defect monitoring. As for the thickness measurement position, for example, in FIG. It is also preferable to perform on-line defect monitoring using infrared rays, near-infrared rays, cameras (image analysis), and the like.

Hereinafter, the present invention will be described in more detail with specific examples of manufacturing the prepreg according to the present invention. The following are examples, and the present invention should not be construed as being limited to the embodiments described below.

FIG. 27 is a schematic diagram of an example of a prepreg manufacturing process and apparatus using the first manufacturing method of the present invention. A plurality of reinforcing fiber bobbins 412 are hung on a creel 411 and pulled out through a direction changing guide 413 . At this time, the reinforcing fiber bundle 414 can be pulled out with a constant tension by the brake mechanism provided to the creel. A plurality of reinforcing fiber bundles 414 pulled out are arranged in order by a reinforcing fiber arranging device 415 to form a reinforcing fiber sheet 416 . In FIG. 27, only three reinforcing fiber bundles are drawn, but in reality, one to several hundred yarns can be used, and the prepreg width and fiber basis weight can be adjusted as desired. be. After that, the sheet is conveyed vertically downward through a widening device 417, a smoothing device 418, and a direction change roll 419. As shown in FIG. In FIG. 27, the reinforcing fiber sheet 416 is conveyed linearly between the reinforcing fiber arranging device 415 and the direction changing roll 419 . Note that the widening device 417 and the smoothing device 418 can be appropriately skipped or not arranged depending on the purpose. Also, the arrangement order of the reinforcing fiber arranging 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 , passes through the reinforcing fiber preheating device 420 and the coating section 430 and reaches the direction changing roll 441 . Applicator 430 can adopt any applicator shape as long as the object of the present invention is achieved. For example, shapes such as those shown in FIGS. 2 and 6 to 9 can be mentioned. Also, if necessary, a bush can be provided as shown in FIG. Furthermore, as shown in FIG. 11, a bar can be provided inside the application section. The apparatus of FIG. 27 is provided with a spray coating device 481 and a curtain coating device 482 after the primary prepreg 471 is formed in the coating section 430 . In FIG. 27, the spray coating device 481 and the curtain coating device 482 are drawn on both sides of the primary prepreg. You can change the order. Then, after spray coating and/or curtain coating, a release sheet 443 can be applied and taken up by a high tension take-up device 444 . FIG. 27 depicts a nip roll as the high tension take-off device 444 . After that, the integrated sheet passes through a follow-up impregnation device 450 equipped with a hot plate 451 and a heating nip roll 452, is cooled by a cooling device 461, is taken up by a take-up device 462, and after peeling off the upper release sheet 446. , and a winder 464 to obtain a sheet-like integrated body 472 consisting of prepreg/release sheet as a product. Since the sheet-like one piece is conveyed in a basic straight line from the direction change roll 441 to the winder 464, the occurrence of wrinkles can be suppressed. In FIG. 27, illustration of a matrix resin supply device and an online monitoring device is omitted.

FIG. 28 is a schematic diagram of another example of the prepreg manufacturing process and apparatus using the first manufacturing method of the present invention. In FIG. 28, since the creel to the coating portion 430 are the same as in FIG. 27, illustration is omitted. In FIG. 28, a release sheet 446 is applied after the primary prepreg 471 is formed, and the high-tension take-off device 444 takes it off. Here, the high tension take-off device 444 shows an example of an S-shaped roll. After peeling off the release sheet on the upper side, the coating can be performed using the spray coating device 481 and the curtain coating device 482 . Either one of the spray coating device 481 and the curtain coating device 482 may be used, or the order may be changed. Thereafter, after applying the upper release sheet, additional impregnation is performed, the upper release liner is peeled off, and the sheet-like unitary prepreg/release sheet is wound up.

Next, with regard to the second manufacturing method, the present invention will be described in more detail with specific manufacturing examples.

FIG. 29a is a schematic diagram of an example of a prepreg manufacturing process using the present invention when a UD base material is used as a reinforcing fiber sheet. A plurality of reinforcing fiber bobbins 412 are hung on a creel 411 and drawn upward through a direction changing guide 413 . At this time, the reinforcing fiber bundle 414 can be pulled out with a constant tension by the brake mechanism provided to the creel. A plurality of reinforcing fiber bundles 414 pulled out are arranged in order by a reinforcing fiber arranging device 415 to form a reinforcing fiber sheet 416 . Although only three reinforcing fiber bundles are drawn in FIG. 29a, in reality, it can be two to several hundred yarns, and can be adjusted to the desired prepreg width and fiber basis weight. be. After that, through a widening device 417, a smoothing device 418, and a modifier application device 421, a reinforcing fiber sheet 422 to which a modifier is applied is obtained. The reinforcing fiber sheet 422 to which the modifier is applied is conveyed vertically downward through the direction changing rolls 419 .

As the modifying agent application device, it is possible to appropriately select and use from various application methods without limitation within the scope of achieving the object of the present invention. For example, spray coating (including meltblowing), curtain coating, and the like can be used.

FIG. 29a shows an example in which the reinforcing fiber sheet 416 is conveyed linearly between the reinforcing fiber arranging device 415 and the modifying agent applying device 421. FIG. The widening device 417 and the smoothing device 418 may be known ones or may be skipped appropriately depending on the purpose, or may be omitted. Also, the arrangement order of the reinforcing fiber arranging device 415, the widening device 417, and the smoothing device 418 can be appropriately changed according to the purpose. The reinforcing fiber sheet 422 to which the modifier is applied 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 coating section 430 . The reinforcing fiber preheating device 420 can be appropriately skipped according to the purpose, or the device can be omitted. Applicator 430 can adopt any applicator shape as long as the object of the present invention is achieved. For example, shapes such as those shown in FIGS. 2 and 6 to 9 can be mentioned. Also, if necessary, a bush can be provided as shown in FIG. Furthermore, as shown in FIG. 11, a bar can be provided inside the application section. In FIG. 12a, a release sheet 446 unwound from a release sheet (upper) feeder 442 can be laminated to a prepreg 471 on a turn-around roll 441 into a sheet-like monolith. Furthermore, a release sheet 446 unwound from a release sheet supply device 442 can be inserted into the lower surface of the sheet-like integral body. Here, a release paper, a release film, or the like can be used as the release sheet. This can be pulled off with a high tension take off device 444 . 29a depicts a nip roll as the high tension take-off device 444. FIG. After that, the integrated sheet passes through a follow-up impregnation device 450 equipped with a hot plate 451 and a heating nip roll 452, is cooled by a cooling device 461, is taken up by a take-up device 462, and after peeling off the upper release sheet 446. , and a winder 464 to obtain a sheet-like integrated body 472 consisting of prepreg/release sheet as a product. Since the sheet-like one piece is conveyed in a basic straight line from the direction change roll 441 to the winder 464, the occurrence of wrinkles can be suppressed. In addition, in FIG. 29a, drawing of a matrix resin supply device and an online monitoring device is omitted.

FIG. 29b is an example of a prepreg manufacturing process using the present invention when a UD base material is used as the reinforcing fiber sheet, similar to the example shown in FIG. 29a. It is different in that the modifier is applied after being directed downward from the horizontal direction to the vertical direction. Also, an example in which the modifier application device 421 is installed after the reinforcing fiber preheating device 420 is shown. The modifier applying device 421 and the reinforcing fiber preheating device 420 may be arranged in an appropriate order. It is preferable to arrange the modifier application device 421 later. As a result, it is possible to prevent contamination of the equipment and rolls due to contact with the modifying agent applied to the reinforcing fiber sheet, and the modifying agent is heated by the reinforcing fiber preheating device 420, and the fluidity of the modifying agent is increased. Dissolution of the modifier in the matrix resin stored in 430 can be suppressed. In FIG. 29b, the running direction of the reinforcing fiber sheet when applying the modifier is downward from the horizontal direction to the vertical direction, but the orientation of the modifier application device may be changed by 90 degrees to apply the modifier. In addition, in FIG. 29b, drawing of a matrix resin supply device and an online monitoring device is omitted.

29a and 29b show an example in which the modifier is applied to the reinforcing fiber sheet being conveyed downward in the horizontal or vertical direction, but it can also be applied on rolls that change direction.

FIG. 30 is a schematic view of another example of a prepreg manufacturing process and apparatus using the present invention when using a UD base material as a reinforcing fiber sheet. In FIG. 30, a reinforcing fiber bundle 414 is pulled out from a creel 411 and directly formed into a reinforcing fiber sheet 416 by a reinforcing fiber arranging device 415. After that, it is linearly conveyed to a widening device 417 and a smoothing device 418. It differs from FIG. 29b in that the sheet 416 is guided upward. With such a configuration, it becomes unnecessary to install a device above, and the installation of a scaffold or the like can be greatly simplified.

FIG. 31 is a schematic diagram of another example of a prepreg manufacturing process and apparatus using the present invention when using a UD base material as a reinforcing fiber sheet. In FIG. 31, a creel 411 is installed on the floor to further straighten the running path of the reinforcing fiber sheet 416 .

FIG. 32 is a schematic diagram of another example of a prepreg manufacturing process and apparatus using the present invention when using a UD base material as a reinforcing fiber sheet. An example of using a simple additional impregnation device instead of the normal additional impregnation device shown in FIG. 29b is shown. 32, since the simple additional impregnation device 453 is installed directly below the coating part 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 miniaturized. In FIG. 32, the heating nip roll 454 is drawn as an example, but depending on the purpose, a small heating S-shaped roll or a non-contact heating device may be used. Another advantage is that the use of the simple additional impregnation device can make the entire prepreg manufacturing device very compact.

30, 31, and 32 are schematic diagrams of another example of the prepreg manufacturing process/apparatus when a unidirectionally arranged reinforcing fiber bundle is used as the reinforcing fiber sheet as in FIG. 29b. By using the reinforcing fiber fabric roll for the unwinding device, 412, and the nip roll for 413, the devices shown in each figure can be applied even when the reinforcing fiber fabric is used.

FIG. 33 shows an example in which 2 rolls-2 sets (4 rolls in total) of a high-tension take-up S-shaped roll 449 as a high-tension take-up device and an "S-wrap roll" type heating S-shaped roll 455 as a supplementary impregnation device are used. Although it is drawn, the number of rolls can of course be increased or decreased according to the purpose. In FIG. 33, the 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. 34 is a schematic diagram of another example of a prepreg manufacturing process and apparatus using the present invention. This example shows an example in which an "S-wrap roll" type heated S-shaped roll 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.

An example using a thread splitting inhibitor is described below as a more specific example.

As a prepreg manufacturing apparatus, a device obtained by removing the widening device 417, the smoothing device 418, and the additional impregnation device 450 from the device shown in FIG.

(Addition of yarn splitting inhibitor)
A plurality of reinforcing fiber bobbins 412 can be hung on a creel 411 and drawn upward through a direction changing guide 413 . The pulled out plurality of reinforcing fiber bundles 414 can be orderly arranged by the reinforcing fiber arranging device 415 to form a reinforcing fiber sheet 416 . Using a modifying agent application device 421, a filament splitting prevention agent can be applied to the formed reinforcing fiber sheet 416, and a filament splitting prevention agent-applied reinforcing fiber sheet 422 can be obtained. The reinforcing fiber sheet 422 to which the yarn splitting prevention agent is applied can be changed from the horizontal direction to the vertical downward direction through the direction change roll 419 and can be made to run, and passes through the reinforcing fiber preheating device 420 and the coating section 430. can be made

As the reinforcing fiber, carbon fiber (“Torayca (registered trademark)” T800S (24K) manufactured by Toray Industries) can be used. The number of reinforcing fiber bobbins can be changed according to the basis weight of the prepreg to be produced, but if 56 yarns are used, a prepreg with a general basis weight can be obtained.

(Method of applying yarn cracking inhibitor)
As a method for applying the anti-thread splitting agent, any applying device can be appropriately selected and used without limitation within the scope of achieving the object of the present invention. For example, spray coating, curtain coating, or the like can be used.

If spray application is used, the anti-split agent can be applied as shown in Figures 35a and 35b. As shown in FIG. 35a, a spray nozzle 510 is installed above the reinforcing fiber sheet 416 so as not to come into contact with it. It can be applied to one side of the running reinforcing fiber sheet 416, and as shown in FIG. Any nozzle other than the spray nozzle can be used as long as it can form droplets of the anti-thread breakage agent and spray them. In FIG. 35a, the reinforcing fiber sheet 416 is provided with the modifier 500, which is a filament prevention agent, on one side, but of course, the spray nozzles 510 can be arranged on both sides of the reinforcing fiber sheet 416 to apply the modifier 500 on both sides. Although omitted in FIGS. 35a and 35b, the spray nozzle 510 can be provided with a mechanism for continuously supplying the modifier, and the basis weight of the modifier supplied to the spray nozzle 510 is the modifier supplied to the spray nozzle 510. can be adjusted by the amount of The modifier to be supplied can also be supplied in the form of a heated and melted one.

When using the melt blowing method, a thread splitting inhibitor can be applied as shown in FIGS. 36a and 36b. As shown in FIG. 36a, a coating head 520 having a discharge part is installed above the reinforcing fiber sheet 416 so as not to contact it, and the modifier 500 that prevents thread cracking is discharged from the installed coating head 520, and discharged. By guiding the modified agent 500 by the air flow 521 , the anti-thread splitting agent can be shaped into fibers and then applied to one side of the reinforcing fiber sheet 416 . As shown in FIG. 36b, the anti-thread splitting agent discharged from the coating head 520 is guided by an air flow and shaped into fibers before reaching the reinforcing fiber sheet. can be crossed and entangled and applied to the reinforcing fiber sheet. As the melt blow method, more specifically, a method as described in Japanese Patent Application No. 2018-511189 can be used. The coating head has a plurality of flow paths for distributing the filament-cracking prevention agent supplied inside in the width direction, and a structure that guides the filament-cracking prevention agent to the discharge part can be used. The ejection part of the coating head has a plurality of holes in the width direction, and by adjusting the area of the holes, the diameter of the fiber shaped by ejection can be adjusted. The interval between applications can also be adjusted. In FIG. 36a, the reinforcing fiber sheet 416 is provided with the modifier 500, which is a thread splitting prevention agent, on one side. Of course, the coating heads 520 can be arranged on both sides of the reinforcing fiber sheet 416 to apply the modifier 500 on both sides. Although omitted in FIGS. 36a and 36b, the coating head is equipped with a mechanism for continuously supplying the anti-thread splitting agent, and the basis weight of the anti-thread splitting agent is the amount of anti-thread splitting agent supplied to the coating head. By adjusting, it is possible to impart the desired yarn splitting prevention agent with a basis weight. A gear pump can also be used as a supply mechanism, and the basis weight of the yarn splitting prevention agent to be applied can be adjusted by adjusting the supply amount by the gear pump used and its rotation speed. Thread splitting inhibitor can be supplied in a heated and melted form.

If curtain coating is used, an anti-split agent can be applied as shown in Figures 37a, 37b and 38a and 38b. As shown in FIG. 37a , the application head 530 is installed above the reinforcing fiber sheet 416 so as not to contact it. It can be applied to one side of the reinforcing fiber sheet 416 to be used. Note that the coating head can also be installed so that the angle formed by the discharge direction of the thread splitting prevention agent and the conveying direction of the reinforcing fiber sheet 416 is 80° or less, as in Japanese Patent Application No. 2018-511188. The coating head is not particularly limited as long as it is capable of planarly ejecting the anti-spinning agent to be supplied, and a head capable of ejecting a resin having a uniform thickness in the width direction and forming a planar or curtain-like film can be used. . More specifically, it is possible to use a structure in which the resin can be discharged from slits that are uniform in thickness and are not intermittent. In FIG. 37a, the reinforcing fiber sheet 416 is provided with the modifier 500, which is a filament prevention agent, on one side. Of course, the coating heads 530 may be arranged on both sides of the reinforcing fiber sheet 416 to apply the modifier to both sides. can. By installing the application head 530 on the direction change roll 419 as shown in FIG. 38a, the angle formed by the ejection direction of the application head and the conveying direction of the reinforcing fiber sheet can be set to 80° or less. When the modifier is applied as shown in FIG. 38a, the diameter of the direction changing roll 419 can be increased to improve workability and coating stability at the start of modifier application. Although omitted in FIGS. 37a, 37b, 38a, and 38b, the coating head 530 is provided with a mechanism for continuously supplying the modifier, and the basis weight of the modifier is supplied to the coating head. By adjusting the amount of the modifier to be used, it is possible to provide the modifier with the desired basis weight. A gear pump can also be used as a supply mechanism, and the applied weight can be adjusted by adjusting the supply amount according to the gear pump used and its rotation speed. Also, the modifier can be heated and melted to be supplied.

(Thread crack prevention agent)
The basis weight of the anti-thread splitting agent to be applied can be 20 g/m ² or less. When the anti-thread splitting agent is applied intermittently, the interval between application of the anti-thread splitting agent in the longitudinal direction can be 30 mm or less at maximum.

Various resins can be used as the component of the thread splitting prevention agent, and the above-described thermosetting resins, thermosetting resin curing agents, thermoplastic resins, polymer particles, and combinations thereof can also be used. The thread splitting inhibitor may be a molten resin melted by heating or a liquid at room temperature. A solution or varnish using a solvent can also be used.

Epoxy resin can also be used as the thermosetting resin. In particular, if the resin is fluid at room temperature, the heating device for melting in the modifier application device can be simplified and simplified, and the resin impregnation of the reinforcing fiber sheet can be easily progressed, so it can be preferably used. As a commercially available epoxy resin, if it is a liquid bisphenol A type epoxy resin, "jER (registered trademark)" 825, "jER (registered trademark)" 827, "jER (registered trademark)" 828, "Epiclon ( registered trademark)”850 (manufactured by DIC Corporation), “Epototh (registered trademark)” YD-128 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), DER-331 (manufactured by Dow Chemical Co.), etc. can be used. , Commercial products of liquid bisphenol F type epoxy resin include "jER (registered trademark)" 806, "jER (registered trademark)" 807, "jER (registered trademark)" 1750, "Epiclon (registered trademark)" 830 (DIC (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), "Epototo (registered trademark)" YDF-170 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), etc., and commercial products of liquid triglycidylaminophenol include p-aminophenol As a precursor, "Araldite (registered trademark)" MY0500, "Araldite (registered trademark)" MY0510 (manufactured by Huntsman Advanced Materials Co., Ltd.) and "jER (registered trademark)" 630 (manufactured by Mitsubishi Chemical Corporation), etc. are used. "Araldite (registered trademark)" MY0600 and "Araldite (registered trademark)" MY0610 (manufactured by Huntsman Advanced Materials Co., Ltd.) having m-aminophenol as a precursor can be used.

A toughness improver can also be mixed with these, and specifically polyamides, polyimides, polyethersulfones, polyetherethersulfones, polyetherimides, polyphenylene oxides, polysulfones, and the like can be used. Commercially available products of polyethersulfone include "Sumika Excel (registered trademark)" PES5003P (manufactured by Sumitomo Chemical Co., Ltd.) and "Virantage (registered trademark)" VW10700 (Solvay Advanced
Polymers Co., Ltd.), "Sumika Excel (registered trademark)" PES7600P (manufactured by Sumitomo Chemical Co., Ltd.), "Ultem (registered trademark)" 1010 (manufactured by Sabic Innovative Plastics Co., Ltd.) as a commercially available polyetherimide, Commercially available polysulfones such as "Virantage (registered trademark)" VW30500 (manufactured by Solvay Advanced Polymers Co., Ltd.) can be used. It should be noted that it is also possible to knead and use not only those in which these are melted, but also those in the form of particles. It is also possible to mix the polymer particles mentioned above.

In addition, the thread splitting prevention agent is kneaded with a phosphorus atom-containing compound such as metal hydroxide, metal oxide, red phosphorus, phosphate ester, and phosphate, a nitrogen-containing compound, and a flame retardant such as antimony trioxide. can also be used.

(Application of matrix resin)
As shown in FIG. 29a, a reinforcing fiber sheet 422 to which a modifier is applied is passed through a coating section 430 to obtain a prepreg having both sides coated with a matrix resin.

As the application part, the application part of the application part 20c type shown in FIG. 7 can be used.

The application part is made of stainless steel, and in order to heat the matrix resin, a plate heater is attached to the outer periphery of the application part, and the temperature and viscosity of the matrix resin can be adjusted while measuring the temperature with a thermocouple. . In addition, the running direction of the reinforcing fiber sheet in the liquid pool is downward in the vertical direction, and the liquid pool is two-step tapered. 10 to 70 mm, and the opening angle of the second stage taper can be 5 to 10°. Further, as a width regulating mechanism, a plate-like bush matching the internal shape of the application portion as shown in FIG. 5 is provided, and furthermore, the installation position of this plate-like bush can be freely changed so that L2 can be adjusted as appropriate. Although it can be adjusted according to the desired basis weight, a prepreg with a general basis weight can be obtained by setting L2 to 300 mm and setting the gap D of the constricted portion to about 0.2 mm. In addition, in order to prevent the matrix resin from leaking from the outlet of the narrowed portion, the outer side of the outlet of the narrowed portion can be blocked for use.

(matrix resin)
A matrix resin that is a thermosetting epoxy resin composition can be used as the matrix resin applied by the application unit 430 . It is a mixture of epoxy resin (aromatic amine-type epoxy resin + bisphenol-type epoxy resin mixture), hardener (diaminodiphenylsulfone), polyethersulfone, and does not contain polymer particles. The viscosity of this matrix resin can be measured using ARES-G2 manufactured by TA Instruments, with a measurement frequency of 0.5 Hz, a heating rate of 1.5° C./min, 3675 Pa s at 40° C., 50 Pa s at 75° C., 90 15 Pa·s at °C and 4 Pa·s at 105 °C. Using this matrix resin, a prepreg can be produced by setting the temperature of the matrix resin at the applied portion to 75 to 105° C. and the running speed of the reinforcing fiber sheet and prepreg to 5 to 25 m/min.

A yarn cracking inhibitor is used as a modifier, and as a method for applying the yarn cracking inhibitor, referring to the description of Japanese Patent Application No. 2018-511189, as shown in FIG. A modifier 500, which is an anti-thread splitting agent, can be applied. A coating head having a plurality of discharge holes in the width direction can be arranged in a non-contact state on the reinforcing fiber sheet 416 conveyed in the horizontal direction. The number of revolutions of the gear pump that supplies the anti-split agent to the coating head is adjusted, the applied weight of the anti-split agent is 10 g / m ² , and the interval between application of the anti-spread agent in the longitudinal direction is 30 mm at the maximum. The component of the anti-cracking agent is the same as the matrix resin, the temperature of the matrix resin in the application part is 90 ° C., the taper at the first stage of the application part has an opening angle of 17 degrees, H = 70 mm, and the taper at the second stage opens. The angle can be 7°. If the running speed of the reinforcing fiber sheet, the reinforcing fiber sheet to which the modifier is added, and the prepreg is set to 20 m/min, the reinforcing fiber sheet can be continuously run for 30 minutes or more without causing thread clogging or thread breakage at the coating portion.

If the fiber-reinforcing agent is not added to the reinforcing fiber sheet, there are fiber cracks with a width of 2 mm or more, resulting in poor quality. can be obtained. For cracking of the prepreg, the obtained prepreg is unwound for 10 m, and the maximum width of the cracked portion where there is no reinforcing fiber is measured with a vernier caliper.

In addition, the impregnation rate of the obtained prepreg by the peeling method can be 50% or more. The impregnation rate by the peeling method is obtained by sandwiching the sampled prepreg with adhesive tape, peeling it, separating the reinforcing fiber with the matrix resin attached and the reinforcing fiber without the matrix resin attached, and measuring the mass of the entire reinforcing fiber sheet. It is calculated from the ratio of the mass of the reinforcing fiber to which the matrix resin is attached.

In addition, the basis weight of 100 mm square in the width direction of the prepreg can be within the range of plus or minus 3% by mass for both the carbon fiber and the resin, and excellent uniformity in basis weight in the width direction can be obtained. In addition, the uniformity of basis weight in the width direction of the prepreg can be evaluated as follows. A prepreg having a width of 300 mm is cut into 100 mm squares in the width direction at the right end, the center, and the left end, and the mass of the prepreg and the mass of the carbon fiber are respectively measured with n=3. The mass of the carbon fiber is measured as a residue obtained by eluting the resin from the prepreg with a solvent. From this, the average value at each sampling position is calculated, and the average values at each sampling position are compared.

Moreover, CFRP can be obtained by laminating 6 layers of this prepreg and curing for 2 hours at 180° C. and 6 kgf/cm ² (0.588 MPa) using an autoclave. The tensile strength is about 2.9 GPa, and a prepreg obtained without adding a thread splitting inhibitor and a prepreg prepared by a conventional hot-melt method using carbon fibers and matrix resin A are laminated and cured in the same manner. The tensile strength of the CFRP obtained in (1) is also about the same as 2.9 GPa. The CFRP tensile strength is measured in the same manner as in the pamphlet of WO2011/118106, and the value obtained by normalizing the volume % of reinforcing fibers in the prepreg to 56.5% is used.

In addition, the surface of the reinforcing fiber sheet 1a to which the anti-cracking agent is applied is only one side of the upper surface, thereby preventing the anti-cracking agent applied to the reinforcing fiber sheet from adhering to the conveying roll 419 and contaminating it. can be done.

By adding a thread splitting prevention agent, the thread splitting of the finally obtained prepreg can be improved without impairing the process stability, and the prepreg has good quality and does not significantly decrease the tensile strength of the laminated and cured CFRP. Obtainable.

<Prepreg manufacturing equipment>
A coating unit of the coating unit 20c type shown in FIG. 7 was used, and the apparatus shown in FIG. 28 was used as the prepreg manufacturing apparatus. In FIG. 28, drawing of a device such as a creel is omitted, and a reinforcing fiber preheating device and subsequent devices are drawn.

<Coating part>
In the application section, a stainless steel block was used as the wall surface member forming the liquid reservoir and the constricted section, and a stainless steel plate was used as the side plate member. Further, in order to heat the matrix resin, a plate heater was attached to the outer periphery of the wall member and the side plate member, and the temperature and viscosity of the matrix resin were adjusted while measuring the temperature with a thermocouple. The running direction of the reinforcing fiber sheet is downward in the vertical direction, and the liquid pool has a two-step tapered shape. there were. Further, as a width control mechanism, a plate-like bush matching the shape of the inside of the application portion as shown in FIG. The width Y of the narrowed portion was set to 300 mm when L2 was 300 mm. The gap D of the narrowed portion was set to 0.18 mm. In this case, the exit slit has an aspect ratio of 1,500. In addition, in order to prevent the matrix resin from leaking from the outlet of the narrowed portion, the lower surface of the outlet of the narrowed portion was closed outside the bush.

<Reinforcing fiber sheet>
The prepreg is produced by using carbon fiber (manufactured by Toray, "Torayca (registered trademark)" T800S (24K)) as a reinforcing fiber, using a thermosetting epoxy resin composition described later as a matrix resin, and using the above equipment to prepare an FRP sheet. A prepreg with a shape was produced. The number of reinforcing fiber bobbins was changed according to the prepreg to be produced, but was set to 56 unless otherwise specified.

<Prepreg manufacturing process>
A reinforcing fiber bundle was pulled out from a plurality of reinforcing fiber bobbins hung on a creel, a reinforcing fiber sheet was formed by a reinforcing fiber arranging device, and was once guided upward by a direction changing roll. After that, the reinforcing fiber sheet was conveyed vertically downward through direction changing rolls, heated to a temperature equal to or higher than the temperature of the coating section by the reinforcing fiber preheating device, guided to the coating section, and coated with the matrix resin. After that, the primary prepreg was pulled out from the coating part, and after being provided with a release sheet, it was taken up by a high-tension take-up device, and the release sheet on the upper side was peeled off. Then, spray coating was performed on the table. After this, an upper release sheet was applied, which was led to a post-impregnation device with hot plates and heated nip rolls for optional post-impregnation. After that, it passed through a cooling device, the upper release paper was peeled off, and the sheet-like integral body of prepreg/release sheet was wound up.

<Matrix resin>
Matrix resin (thermosetting epoxy resin composition):
It is a mixture of epoxy resin (aromatic amine type epoxy resin + bisphenol type epoxy resin mixture), curing agent (diaminodiphenylsulfone) and polyethersulfone, and does not contain polymer particles. The viscosity of this thermosetting epoxy resin 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. 15 Pa·s and 4 Pa·s at 105°C.

<Liquid for spray coating>
A bisphenol type liquid epoxy resin was used. When the viscosity of this liquid epoxy resin was measured using ARES-G2 manufactured by TA Instruments at a measurement frequency of 0.5 Hz and a temperature of 25° C., it was 10 Pa·s.

<Spray application conditions>
The coating head temperature was 25° C., the single hole area of the die was 0.025 mm ² , the single hole discharge rate was 0.16 g/min, and the number of holes in the width direction was 220. Air was supplied at a flow rate of 0.15 MPa, and the coating height h from the carbon fiber sheet to the lower surface of the coating head (face of the nozzle) was 50 mm.

<Evaluation of continuous running performance>
In order to evaluate the continuous runnability at the application part of the reinforcing fiber sheet, the sheet was run continuously for 30 minutes, and "Good" was given when there was no fluff clogging or thread breakage, and "Bad" when fluff was clogged and thread breakage occurred.

In addition, in order to evaluate signs of fluff clogging, the coated portion was disassembled after continuous running for 60 minutes and 120 minutes, and the wetted surface of the wall surface member was visually observed to examine the presence or absence of fluff. "Poor" fluff-preventing properties are those in which fluff adheres to the vicinity of the constricted portion after continuous running, and those in which fluff adheres to the portion far from the constricted portion 23 (near the upper portion of the liquid pool portion 22) after continuous running. The anti-fluff property was evaluated as "Fair" and "Good" when no fluff adhered to the wetted surface of the wall surface member 21 after continuous running.

In addition, it was continuously run at a running speed of 20 m / min for 60 minutes, and the reinforcing fiber sheet directly above the liquid pool was cracked in the fiber bundle (the part where the sheet-like carbon fiber bundle was torn in a vertical streak) and the edge of the fiber bundle was broken. The time for uniform running without (a portion where the carbon fiber bundles overlap) was measured. "Excellent" indicates that the ratio of the time during which the fiber bundle is running uniformly without cracks or end breakage of the fiber bundle accounts for 90% or more of the total running time, and "Good" indicates that it is 50% or more and less than 90%. ", 10% or more and less than 50% were evaluated as "Fair", and less than 10% as "Poor".

<Evaluation of degree of impregnation>
・Peeling method (when the degree of impregnation is low)
The sampled prepreg was sandwiched between adhesive tapes and peeled off to separate the reinforcing fibers to which the matrix resin was attached and the reinforcing fibers to which the matrix resin was not attached. Then, the ratio of the mass of the reinforcing fibers with the matrix resin adhered to the mass of the entire reinforcing fiber sheet put in was taken as the impregnation rate of the matrix resin by the peeling method.

・Water absorption rate (when the degree of impregnation is high)
According to the method described in JP-T-2016-510077, the prepreg was cut into 10 cm × 10 cm pieces, and one side was 5 mm, and it was calculated from the mass change when immersed in water for 5 minutes.

[Examples 1 to 4]
A prepreg was produced by using the thermosetting epoxy resin composition (matrix resin) in the coating portion and using the liquid epoxy resin in the spray coating. However, in this example, additional impregnation after spray coating was not performed. The temperature of the matrix resin in the liquid reservoir was set at 90° C. (equivalent to 15 Pa·s). The running speed of the reinforcing fiber sheet and prepreg was set to 20 m/min.

The relationship between the width L2 of the lower end of the width regulating mechanism and the width W of the primary prepreg, and the running of the primary prepreg in the coating portion when the height H at which the cross-sectional area of the coating portion continuously decreases is varied. Table 1 shows the stability evaluation results. From this, it can be seen that the smaller L2−W and the larger H are, the more stable running performance of the primary prepreg is improved. In addition, when the primary prepreg was collected from the lower part of the simple additional impregnation device without performing the simple additional impregnation, and the impregnation rate was examined by the peeling method, it was 50 to 60% in all cases, indicating that the impregnation was progressing in the coated part. It was confirmed. Further, the uniformity of basis weight in the width direction of the primary prepreg sampled as described above was evaluated as follows. A prepreg having a width of 300 mm was cut into 100 mm squares in the width direction at the right end, the center and the left end, and the mass of the prepreg and the mass of the carbon fiber were each measured with n=3. The mass of the carbon fiber was measured as a residue obtained by eluting the resin from the prepreg with a solvent. From this, the average value at each sampling position was calculated, and when the average values at each sampling position were compared, both the carbon fiber and the resin were within the range of plus or minus 2% by mass, indicating excellent basis weight uniformity. Met. In addition, the prepreg surface had excellent tackiness due to the effect of the sprayed liquid.

[Comparative Example 1]
An attempt was made to produce a prepreg in the same manner as in Example 1 under the conditions shown in Table 1, using the portion without a continuously decreasing cross-sectional area (H=0) shown in FIG. Immediately after the start of running in minutes, the reinforcing fiber sheet was clogged and the continuous running performance was poor.

[Example 5]
After the matrix resin was applied under the conditions of Example 1, spray coating was performed, and the substrate was led to the additional impregnation device for additional impregnation. When the water absorption rate of this prepreg was examined, it was found to be a sufficient impregnation degree of 5%.

Next, six layers of the obtained prepreg were laminated and cured at 180° C. and 6 kgf/cm ² (0.588 MPa) for 2 hours using an autoclave to obtain CFRP. Each CFRP obtained had a tensile strength of 3.0 GPa and had mechanical properties suitable as a structural material for aerospace applications. The CFRP tensile strength was measured in the same manner as in the pamphlet of WO2011/118106, and the value obtained by normalizing the volume % of reinforcing fibers in the prepreg to 56.5% was used.

[Reference example 1]
Using carbon fiber and thermosetting epoxy resin (matrix resin), a prepreg made by a conventional hot-melt method was cured in an autoclave at 180°C and 6 kgf/cm ² (0.588 MPa) for 2 hours. The strength was 2.9 GPa.

The prepreg obtained by the production method of the present invention is used as FRP represented by CFRP for aerospace applications, structural materials and interior materials for automobiles, trains, ships, etc., pressure vessels, industrial material applications, sports material applications, medical equipment. It can be widely applied to applications, housing applications, civil engineering and construction applications, and the like.

1 Reinforcing fiber 1a Reinforcing fiber sheet 1b Reinforcing fiber sheet 1c to which a modifier is applied Primary prepreg 1d Prepreg 2 Matrix resins 3, 3a, 3b Release sheet 11 Creel 12 Arranging devices 13, 14 Conveying rolls 15 Winding device 16 , 16a, 16b Feeding device 20 Coating part 20b Another coating part 20c Another coating part 20d Another coating part 20e Another coating part 21a, 21b Another wall surface member 21c, 21d Other Wall surface members 21e and 21f having different shapes Wall surface members 21g and 21h having different shapes Wall surface members 21i and 21j having different shapes Region 22b Region 22c where the cross-sectional area of the liquid pool does not decrease Region 23 where the cross-sectional area of the liquid pool intermittently decreases Narrowed portions 24a, 24b Side plate member 25 Outlet 26 Gap 27, 27a, 27b Width regulating mechanism 28 Modified Material supplying device 30 Coating parts 31a and 31b of Comparative example 1 Wall member 32 of Comparative example 1 Liquid pooling part 33 of Comparative example 1 Areas 35a and 35b of the liquid pooling part of Comparative example 1 whose cross-sectional area decreases intermittently , 35c bar 41 spray coating device 42 curtain coating device 43 liquid 44 air flow 45 table 46 liquid or solidified product thereof or mixture thereof 47 film 48 edge air 49 surface air 50 roll 100 coating device B depth C of liquid pool 22 Height D to the upper liquid level of the liquid pool 22 Gap of the constricted portion G Width regulation position H Vertical height L at which the cross-sectional area of the liquid pool 22 continuously decreases Width R of the liquid pool 22 Ra, Rb Eddy flow T Circulating flow W Width Y of primary prepreg 1b measured immediately below constricted portion 23 Width Z of constricted portion 23 Conveying direction θ of reinforcing fiber sheet, primary prepreg, and prepreg Open angle E of tapered portion End Blowing direction F of face air Blowing direction N of face air Neck-in h Application height α Applied reinforcing fiber sheet 417 Widening device 418 Smoothing device 419 Direction changing roll 420 Reinforcing fiber preheating device 421 Modifier applying device 422 Reinforcing fiber sheet 430 with modifier applied Applicator 431 Table 441 Direction changing roll 442 Release Sheet supply mechanism 443 Release sheet 44 4 High-tension take-up device 445 Direction changing roll 446 Release sheet 447 Laminated roll 448 High-tension take-up device 449 High-tension take-up S-shaped roll 450 Additional impregnation device 451 Hot plate 452 Heating nip roll 453 Simple additional impregnation device 454 Heating nip roll 455 Heating S-shaped roll 456 Contact roll 461 Cooling device 462 Take-up device 463 Release sheet (upper) winding device 464 Winder 471 Primary prepreg/prepreg 472 Sheet-like integrated product 481 Spray coating device 482 Curtain coating device 500 Modifier 510 Spray nozzle 520 application head 521 airflow 530 application head

Claims (12)

The matrix resin is applied to the reinforcing fiber sheet by passing the reinforcing fiber sheet substantially vertically downward into the application section in which the matrix resin is stored, and then the primary prepreg pulled out from the application section is further coated with the matrix resin. In a method for manufacturing a prepreg by spray coating by discharging a liquid, the coating section includes a liquid pool section communicating with each other and a constricted section positioned below the liquid pool section, and the liquid pool section is made of reinforcing fibers. A method of manufacturing a prepreg, wherein the narrowed portion has a slit-shaped cross section and has a smaller cross-sectional area than the upper surface of the liquid pool portion. The matrix resin is applied to the reinforcing fiber sheet by passing the reinforcing fiber sheet substantially vertically downward into the application section in which the matrix resin is stored, and then the primary prepreg pulled out from the application section is further coated with the matrix resin. A prepreg manufacturing method that performs curtain coating that discharges a liquid, wherein the coating section includes a liquid pool section communicating with each other and a constricted section positioned below the liquid pool section, and the liquid pool section comprises reinforcing fibers. A method of manufacturing a prepreg, wherein the narrowed portion has a slit-shaped cross section and has a smaller cross-sectional area than the upper surface of the liquid pool portion. A prepreg manufacturing method in which a matrix resin is applied to a reinforcing fiber sheet by passing a reinforcing fiber sheet substantially vertically downward through an application section in which a matrix resin is stored, wherein the application sections are communicated with each other. and a narrowed portion positioned below the liquid pooled portion, the liquid pooled portion having a portion in which the cross-sectional area continuously decreases along the running direction of the reinforcing fiber sheet, and the narrowed portion has a slit-shaped cross section and a cross-sectional area smaller than the upper surface of the liquid pool, and before the reinforcing fiber sheet is passed through the application section, the reinforcing fiber sheet is added with a thread cracking prevention agent, a toughness improving agent, A method for producing a prepreg to which at least one modifier selected from the group consisting of a flame retardant and a fluff sizing agent is applied. The method for producing a prepreg according to claim 3, wherein the modifier is applied to the reinforcing fiber sheet after application such that the modifier has a basis weight of 20 g/m ² or less. 5. The method for producing a prepreg according to claim 3 or 4, wherein the modifier is applied continuously in the longitudinal direction of the reinforcing fibers, or the coating interval is within a maximum of 30 mm. The method for producing a prepreg according to any one of claims 3 to 5, wherein the modifier is a thread splitting inhibitor. Claims 1 to 6, wherein the relationship between the width (L) of the lower portion of the liquid pool portion in the arrangement direction of the reinforcing fibers and the width (W) of the primary prepreg immediately below the constricted portion satisfies L≤W+10 (mm). A method for producing a prepreg according to any one of items 1 to 3. A width regulating mechanism for regulating the width of the reinforcing fiber sheet is provided in the liquid pool, and the width (W) of the primary prepreg immediately below the constricted portion and the width (L2) regulated by the width regulating mechanism at the lower end of the width regulating mechanism. satisfies L2≦W+10 (mm). The method for producing a prepreg according to any one of claims 1 to 8, wherein the vertical height of the portion where the cross-sectional area of the liquid reservoir continuously decreases is 10 mm or more. A method for producing a prepreg, wherein the prepreg obtained by the method for producing a prepreg according to any one of claims 1 to 9 is further impregnated. A method for producing a prepreg tape by slitting the prepreg obtained by the method for producing a prepreg according to any one of claims 1 to 10 . A method for producing a fiber-reinforced composite material, in which a prepreg obtained by the method for producing a prepreg according to any one of claims 1 to 10 or a prepreg tape obtained by the method for producing a prepreg tape according to claim 11 is molded. .

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