JP7140131B2 - Multi-layer prepreg with release sheet, prepreg roll, prepreg tape and composites - Google Patents

Description

TECHNICAL FIELD The present invention relates to a prepreg that can achieve both vacuum pressure moldability and handleability.

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.

FRP obtains an intermediate base material by impregnating reinforcing fibers with a matrix resin. Among the intermediate base materials, sheet-shaped prepregs are widely used. In this case, prepregs are laminated and molded to produce FRP. requires heat curing. Autoclaves have traditionally been used for heat curing, and since the resin flows in the prepreg moderately during the curing process due to heat and pressure, voids are less likely to form in the FRP, and FRP with excellent mechanical properties can be obtained. . However, since an autoclave is a pressure vessel, the initial investment for an autoclave that can process large-sized materials for aerospace use is large, and a molding method that does not use an autoclave has been desired.

For this reason, as described in Patent Document 1, vacuum pressure molding using a vacuum oven, which requires a relatively small initial investment and is easy to increase in size, has been studied. However, in vacuum pressure molding, since the differential pressure that promotes the impregnation of the matrix resin is 1 atm or less, the impregnation time is longer than in the autoclave molding. There is a problem that voids tend to remain inside. Also, in order to reduce the voids, it was necessary to lengthen the time under heating vacuum. For this reason, as described in Patent Document 1, the vacuum pressure molding method is improved to shorten the impregnation time, or as described in Patent Documents 2 and 3, prepregs with unimpregnated portions are intentionally laminated. Therefore, it has been studied to form a degassing path to promote the removal of volatile matter and suppress the generation of voids.

JP 2017-179357 A International publication WO2012/135754 pamphlet U.S. Pat. No. 6,139,942

However, in the prepreg with the unimpregnated portion left as described in Patent Documents 2 and 3, the unimpregnated portion is concentrated in the central portion of the prepreg. Since the carbon fibers to which the matrix resin is not adhered are likely to fall apart in some parts, the prepreg tends to peel off or shift in the non-impregnated parts, resulting in poor shape stability. For this reason, the prepreg sheet or the prepreg roll is likely to have a defective shape during transportation in the prepreg manufacturing process or in the process of finally winding up the prepreg into a roll shape. In addition, in the prepreg cutting and slitting process, reinforcing fiber fluff may occur from the non-impregnated part of the cut surface, and in the prepreg lamination process, when using wide prepreg, the non-impregnated part may occur during the lamination process. However, troubles such as peeling and slippage of the film tended to occur.

Furthermore, in recent years, devices called ATL (Automated Tape Laying) and AFP (Automated Fiber Placement), which automatically laminate narrow prepregs and prepreg tapes, have been widely used in order to improve the efficiency of the prepreg lamination process. However, if the automatic lamination speed is increased, there is a possibility that troubles such as deformation and peeling of the prepreg tape will occur. In this way, conventional prepregs with an unimpregnated portion left in the central portion tend to have poor handling properties in the prepreg manufacturing process, the prepreg roll storage process, the prepreg cutting/slitting process, and the laminating process. .

Thus, a prepreg that is excellent in handleability while leaving an unimpregnated portion for forming a degassing path has not yet been established.

An object of the present invention is to provide a prepreg that has both vacuum pressure moldability and handleability with respect to a prepreg that has a non-impregnated portion.

The prepreg of the present invention for solving the above problems is a multilayer structure prepreg in which an impregnated layer in which a matrix resin is impregnated in a reinforcing fiber sheet and a non-impregnated layer are alternately laminated, wherein the upper surface and the lower surface of the multilayer structure prepreg are Consists of an impregnated layer, having at least one impregnated layer in the inner layer portion of the multilayer structure prepreg excluding the upper and lower surfaces, and a release sheet bonded to either or both of the upper surface and the lower surface of the multilayer structure prepreg a multi-layered prepreg with a release sheet.

Moreover, the prepreg roll of the present invention is obtained by winding the multilayer structure prepreg with the release sheet. Furthermore, the prepreg tape having a width of 30 mm or less according to the present invention comprises the multi-layered prepreg. Furthermore, the composite material of the present invention is obtained by molding the above-mentioned multi-layer structure prepreg with release sheet, prepreg roll or prepreg tape.

Furthermore, a liquid pool portion in which matrix resin as a coating liquid is stored and which has a portion in which the cross-sectional area continuously decreases downward in the vertical direction, and a constricted portion having a slit-shaped outlet communicating with the lower end of the liquid pool portion. A method for manufacturing a prepreg in which a reinforcing fiber sheet is passed vertically downward through a coating portion having a and a step of uniting the plurality of reinforcing fiber sheets inside the application section after introduction.

According to the prepreg of the present invention, it is possible to achieve both reduction of voids during vacuum pressure molding and handling of the prepreg. can be done.

1 is a cross-sectional photograph of a multi-layered prepreg according to an embodiment of the present invention; FIG. 2 is a cross-sectional photograph of a multilayer structure prepreg of another embodiment different from FIG. 1. FIG. 1 is a schematic view of one embodiment of a manufacturing method for manufacturing a multilayer prepreg of the present invention; FIG. FIG. 4 is a schematic diagram of a manufacturing method for manufacturing a multilayer structure prepreg of the present invention in another embodiment from FIG. 3 ; FIG. 4 is a detailed cross-sectional view enlarging the portion of the application unit 20 in FIG. 3 ; 4 is a bottom view of the application unit 20 in FIG. 3 as seen from the direction of A in FIG. 3. FIG. FIG. 4 is a cross-sectional view illustrating the structure of the inner layer portion of the coating section when the coating section 20 in FIG. 3 is viewed from the direction of B in FIG. 3 ; 8 is a cross-sectional view showing the flow of matrix resin 4 in gap 26 in FIG. 7. FIG. It is a figure which shows the installation example of a width control mechanism. FIG. 4 is a detailed cross-sectional view of an application portion 20b of another embodiment different from that of FIG. 3; FIG. 11 is a detailed cross-sectional view of an application portion 20c of another embodiment different from that of FIG. 10; FIG. 11 is a detailed cross-sectional view of an application section 20d of another embodiment different from that of FIG. 10; FIG. 11 is a detailed cross-sectional view of an application portion 20e of another embodiment different from that of FIG. 10; FIG. 4 is a detailed cross-sectional view of the application unit 30 of an embodiment different from this manufacturing method. FIG. 4 is a detailed cross-sectional view enlarging the portion of the application unit 20 in FIG. 3 ; FIG. 16 is a detailed cross-sectional view of an application portion 20a of another embodiment different from that of FIG. 15; FIG. 9B is a detailed view for explaining the arrangement of the width direction restricting members, with reference to the view of FIG. 9A; FIG. 4 is a detailed cross-sectional view of an application portion 20f according to one embodiment of the present invention; FIG. 4 is a detailed cross-sectional view of the applicator 40 and its vicinity, showing an embodiment different from the present invention.

Preferred embodiments of the invention are described below. 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. .

FIG. 1 shows a cross-sectional photograph of a multilayer structure prepreg according to one embodiment of the present invention. In FIG. 1, the layer structure is impregnated layer/non-impregnated layer/impregnated layer/non-impregnated layer/impregnated layer from the top. This is a structure in which impregnated layers are arranged on the outer and inner layers in the prepreg cross section, and non-impregnated layers are arranged on the upper and lower surfaces of the central impregnated layer. It is the smallest unit. In the present invention, the impregnated layer includes a layer formed by bonding two impregnated layers with a matrix resin.

By arranging the impregnated layer on the outside, the tackiness of the prepreg is ensured, and the sticking property in the prepreg lamination process is improved. In particular, 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. Therefore, the tackiness of the prepreg is very important in this process. In addition, the adhesion between the multi-layered prepreg and the release sheet is improved, and separation between the multi-layered prepreg and the release paper can be suppressed.

On the other hand, by having the impregnated layer also in the inner layer of the prepreg cross section, the inner layer of the prepreg is fixed with the impregnated layer, and the reinforcing fibers in the prepreg are prevented from coming apart. It is possible to suppress the deformation and ensure the shape retention of the prepreg. Further, by fixing the prepreg inner layer portion with the impregnated layer, even if the prepreg has a non-impregnated portion, the prepreg is given appropriate rigidity, and the prepreg handleability is improved. Thus, by adopting the layer structure of the present invention, even if there is an unimpregnated layer, the prepreg does not lose its handleability, and it is possible to realize good shape retention and handleability of the prepreg. .

Reinforcing fibers include carbon fiber, glass fiber, metal fiber, metal oxide fiber, metal nitride fiber, organic fiber (aramid fiber, polybenzoxazole fiber, polyvinyl alcohol fiber, polyethylene fiber, polyamide fiber, polyester fiber, etc.). can be exemplified, but it is preferable to use carbon fiber from the viewpoint of mechanical properties and lightness of FRP.

Also, the reinforcing fibers can be provided to the prepreg manufacturing process as a reinforcing fiber sheet in which the reinforcing fibers are arranged to form a sheet-like article. At this time, as the reinforcing fiber sheet, a unidirectional material (UD base material) in which a plurality of reinforcing fibers are arranged on a surface in one direction, a sheet in which reinforcing fibers are arranged in a multiaxial manner, or arranged randomly. and reinforced fiber fabrics. 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 non-woven 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 of being able to design the structure and characteristics of the upper or lower surface of the fabric and the inner layer of the fabric. 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. .

The multi-layer prepreg among the multi-layer prepregs with a release sheet of the present invention is a multi-layer prepreg in which a reinforcing fiber sheet is impregnated with a matrix resin. It is important to have a structure in which non-impregnated layers that are not impregnated or impregnated insufficiently are laminated. Here, the impregnated portion and the non-impregnated portion are first defined. The impregnated portion refers to the portion where the matrix resin is attached to the reinforcing fibers and the portion where only the matrix resin exists, while the non-impregnated portion refers to the portion where the matrix resin is not attached to the reinforcing fibers and the reinforcing fibers are not attached. It refers to the exposed portion (dry reinforcing fiber portion) and the void portion where neither reinforcing fiber nor matrix resin is present. The impregnated layer and the non-impregnated layer are defined in the prepreg cross section when the prepreg is cut in the thickness direction. In the present invention, the prepreg thickness direction cross section is simply referred to as a prepreg cross section. In the present invention, the impregnated layer is a region having a horizontal non-impregnated portion ratio of less than 7% in the prepreg cross section, and the non-impregnated layer is a region having a horizontal non-impregnated portion ratio of 7% or more. .

The non-impregnated portion ratio is obtained by the following procedure. A prepreg cross section for this purpose can be obtained, for example, as follows. That is, the prepreg is frozen at −18° C. in a freezer, and after taking it out of the freezer, the prepreg can be quickly cut with a cutter at room temperature to obtain a prepreg cross section. A cross-sectional photograph of the prepreg cross section is taken as follows using a scanning electron microscope (SEM) or the like. That is, the upper and lower surfaces of the prepreg are placed in the same field of view, and the lines on the upper and lower surfaces of the prepreg are aligned in the horizontal direction of the photograph as much as possible. The vertical size of the prepreg cross-sectional photograph is set to 250 to 600 μm, and the horizontal size is set to 350 to 900 μm. If the prepreg cross section does not fit within this size, the photograph may be divided into a plurality of sheets. Then, in the photograph of the cross section of the prepreg, a reference line is drawn horizontally so as to be in contact with the upper surface of the prepreg, and horizontal auxiliary lines are drawn every 10 μm in the vertical direction (longitudinal direction). Then, the length (L _U ) of the unimpregnated portion on this horizontal auxiliary line is measured. Next, the length (L _P ) of the prepreg portion on the horizontal auxiliary line is measured. Then, the unimpregnated portion ratio (%)=(L _U /L _P )×100 (%) is obtained. Then, the non-impregnated area ratio obtained by a certain horizontal auxiliary line is taken as the non-impregnated area ratio of a band-like region having a thickness of 5 μm above and below that horizontal auxiliary line, that is, a thickness of 10 μm. As a result, the boundary between the impregnated layer and the non-impregnated layer becomes an intermediate portion between the horizontal auxiliary lines with the non-impregnated portion ratio of less than 7% and the horizontal auxiliary lines with the non-impregnated portion ratio of 7% or more.

In the present invention, it is important that prepreg cross-sectional slices are produced at three different points, and that the layer structure of the present invention is formed in all of the prepreg cross-sectional photographs. The minimum unit of the layered structure of the present invention is 5 layers, but it may be 7 layers or more depending on the location. Further, as long as all three different points have the layer structure of the present invention, the layer thickness and the layer position in the prepreg thickness direction may be different for each of the three different points, and the number of layers may be different. can be different.

In the non-impregnated layer, when the maximum value of the non-impregnated portion ratio is 25% or more, it is advantageous for reducing voids during vacuum pressure molding, and is preferable. On the other hand, when the maximum value of the non-impregnated portion ratio is 60% or less, peeling in the non-impregnated portion can be suppressed, and the shape stability of the prepreg can be improved, which is preferable.

Since the matrix resin is not attached to the dry reinforcing fibers, the cross-sectional shape of the reinforcing fibers can be clearly observed in the prepreg cross-sectional photograph. can be ambiguous. Moreover, if the matrix resin is not adhered to the reinforcing fibers, the reinforcing fibers are likely to separate from each other, often forming voids.

Hereinafter, examples of the prepreg of the present invention will be described in more detail with reference to the drawings.

1 and 2 show examples of cross-sectional photographs (SEM) of the multilayer structure prepreg of the present invention. In the cross-sectional photograph, a reference line was drawn on the upper surface of the prepreg, and horizontal auxiliary lines were drawn every 10 μm below the reference line to obtain the non-impregnated area rate (horizontal auxiliary lines are omitted in FIGS. 1 and 2). A dashed line indicates a boundary separating an impregnated layer and an unimpregnated layer between a horizontal auxiliary line with an unimpregnated portion ratio of less than 7% and a horizontal auxiliary line with an unimpregnated portion ratio of 7% or more. FIG. 1 is a typical example of the invention. The first layer is an impregnated layer on the upper surface of the prepreg, and the cross-sectional shape of the reinforcing fibers is unclear, indicating that the matrix resin is impregnated. Although the first layer includes small voids (cross-sectional area of about 70 μm ² ) of about 10 μm on one side, most of the layer is an impregnated portion. It can be seen that impregnated portions and voids are alternately arranged in the horizontal direction in the second layer, which is the non-impregnated layer. Moreover, the maximum value of the non-impregnated portion ratio in the second layer is 45%. In the third layer, which is an impregnated layer, there are some portions including small voids (cross-sectional area of about 120 μm ² ) near the central portion, but almost the entire layer is an impregnated portion. Moreover, the thickness of the third layer is 50 μm or more. It can be seen that impregnated portions and voids are alternately arranged in the horizontal direction in the fourth layer, which is the non-impregnated layer. Moreover, the maximum value of the non-impregnated portion ratio in the fourth layer is 30%. The fifth layer (layer on the lower surface of the prepreg), which is an impregnated layer, has a portion including a small void (cross-sectional area of about 170 μm ² ) on the right side, but most of the layer is an impregnated portion.

FIG. 2 is an example of a multilayer structure prepreg of the present invention different from FIG. The first layer is the impregnation layer on the upper surface of the prepreg, and it can be seen that the matrix resin is impregnated to such an extent that the cross-sectional shape of the reinforcing fibers cannot be confirmed. Also, almost all of the layers are impregnated portions. It can be seen that in the second layer, which is the non-impregnated layer, large voids and large dry reinforcing fiber aggregates are horizontally arranged in the impregnated portion. A portion where the dry reinforcing fibers are aggregated to form a large area is called a dry reinforcing fiber aggregate portion. In addition, the dry reinforcing fiber portion appears to split vertically. The maximum non-impregnated portion ratio in the second layer is 49%. The third layer, which is the impregnated layer, contains two small voids (with cross-sectional areas of about 310 μm ² and about 220 μm ² ) on the left side, but almost the entire layer is impregnated. Moreover, the thickness of the third layer is 50 μm or more. It can be seen that the fourth layer, which is the non-impregnated layer, has a large dry reinforcing fiber assembly part in the central part, and is split vertically in it. Moreover, the maximum value of the non-impregnated portion ratio in the fourth layer is 54%. Almost all of the fifth layer (the layer on the lower surface of the prepreg), which is the impregnated layer, is the impregnated portion.

In the example of FIGS. 1 and 2, the second and fourth layers, which are the non-impregnated layers, include the dry reinforcing fiber assembly part and the void as well as the impregnated part, which suppresses peeling and displacement in the non-impregnated part. and the shape stability of the prepreg as a whole can be improved. In addition, even when the prepreg is formed into a roll shape and placed vertically, it is possible to greatly suppress the collapse of the roll. Specifically, the maximum value of the non-impregnated portion is preferably 60% or less.

Further, when the impregnated layer thickness of the prepreg inner layer portion is set to 30 μm or more, the shape stability of the prepreg as a whole can be further improved.

In addition, it is preferable that the number of large voids and large dry reinforcing fiber aggregates is zero in the prepreg cross section in the impregnated layer because the shape stability of the prepreg as a whole can be improved. Here, the size of large voids and large dry reinforcing fiber aggregates is 500 μm ² or more in cross-sectional area.

In the present invention, the non-impregnated layer forms a deaeration path during molding, and can suppress or prevent the generation of voids derived from volatile components contained in the matrix resin. This effect is particularly useful during vacuum pressure molding.

1 and 2 show an example of five layers of impregnated layer/non-impregnated layer/impregnated layer/non-impregnated layer/impregnated layer. Of course, a prepreg having a multi-layered structure is also possible. When the thickness of the entire prepreg is constant, increasing the number of layers reduces the thickness of the non-impregnated portion relatively, so that the shape stability of the prepreg as a whole can be further improved.

In the prior art, when partially impregnated prepregs are laminated, an air layer tends to be sandwiched between the prepregs, which tends to remain as voids during molding. Since the prepreg is already laminated in the structure, the possibility of sandwiching an air layer between the prepregs can be greatly reduced.

Further, in order to improve the toughness and impact resistance of FRP, interlaminar reinforcing particles can be incorporated into the prepreg as described in Japanese Patent Application Laid-Open No. 1-104624. Since the interlaminar reinforcing particles form a matrix resin layer between reinforcing fiber layers, when this is applied to the present invention, it can be contained in the impregnated layers on the upper and lower surfaces of the multilayer structure prepreg. preferable. It is more preferable that the interlayer reinforcing particles are contained in the impregnation layer of the inner layer portion in addition to the upper and lower surfaces of the multilayer structure prepreg. That is, it is more preferable to have a form in which two thin prepregs containing interlayer reinforcing particles are bonded to the impregnated layer.

In the prepreg containing the interlaminar reinforcing particles, two thin prepregs are laminated as an example, but three, four, or more prepregs may be laminated. In particular, when laminating thin-layer prepregs in multiple layers, the toughness and impact resistance of FRP can be further improved, which is preferable.

Further, it is preferable that the arrangement of the reinforcing fibers in the plane direction is substantially the same in the prepreg, because it is easy to design the mechanical properties and anisotropy of the FRP by the laminated structure of the prepreg. Here, the fact that the arrangement of the reinforcing fibers in the plane direction is substantially the same in the prepreg means that when a unidirectional base material (UD base material) in which the reinforcing fibers are aligned in one direction is used, all of the above It means that the reinforcing fibers are oriented in the 0° direction on the horizontal auxiliary line of . Also, when a normal fabric is used, it means that the number of reinforcing fibers in the 0° direction and the 90° direction are the same. When a bias substrate is used, it means that the number of reinforcing fibers in each bias direction is the same. These can be obtained by stacking a plurality of reinforcing fiber sheets of the same standard in the same direction to produce a multilayer structure prepreg.

In addition, the multilayer prepreg with a release sheet of the present invention has a release sheet laminated on at least one side of the multilayer prepreg. becomes possible.

The matrix resin used in the multilayer structure prepreg according to the present invention can be appropriately selected depending on the application, but generally contains a thermoplastic resin or a thermosetting resin. The matrix resin may be a resin melted by heating or a resin that is liquid 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 a polymer blend alloy.

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 coating liquid, 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.

Moreover, in the present invention, inorganic particles or organic particles can be contained in the matrix resin. 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.

In addition, the prepreg of the present invention may contain polymer particles such as the interlayer reinforcing particles described above, and the polymer particles are generally contained in the matrix resin. At this time, if the glass transition temperature (Tg) or melting point (Tm) of the polymer particles is higher than the coating liquid 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 interlayer resin layer of CFRP, it is preferable to retain the polymer particles in the interlayer resin layer. 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 bundle of reinforcing fibers and can remain in the 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 obtained CFRP can be optimized.

In the multilayer structure prepreg of the present invention, the degree of impregnation with the matrix resin is desirably high within a range that does not impair the vacuum pressure moldability. The impregnation state of the matrix resin can be confirmed by tearing the sampled multilayer structure prepreg and visually inspecting the inner layer, but it is possible to evaluate more quantitatively, for example, by a peeling method. . The impregnation rate of the coating liquid by the peeling method can be measured as follows. That is, the sampled multilayer structure prepreg is sandwiched between adhesive tapes, which are peeled off to separate the reinforcing fibers to which the matrix resin is adhered and the reinforcing fibers to which the matrix resin is not adhered. 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. The degree of impregnation can also be evaluated from the water absorption of the prepreg using capillary action, and the lower the water absorption, the higher the degree of impregnation. More specifically, the method described in Japanese Patent Publication No. 2016-510077 can be applied.

In the present invention, the width of the multi-layer structure prepreg is not particularly limited, and may be as wide as several tens of cm to 2 m, or as a tape having a width of several mm to several tens of mm, and the width may be selected according to the application. can do. 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. Therefore, in the present invention, the width is preferably 30 mm or less when forming a prepreg tape.

As described above, the prepreg of the present invention has been described. Next, specific manufacturing methods for obtaining the prepreg of the present invention will be specifically described with examples. A manufacturing method for efficiently obtaining a prepreg having a multilayer structure according to the present invention has not been known in the past. Therefore, an unprecedented manufacturing method is used to obtain the prepreg of the present invention. The present invention should not be construed as being limited to the specific examples described below.

Specifically, a liquid pool portion in which matrix resin is stored and which has a portion in which the cross-sectional area continuously decreases downward in the vertical direction; a constricted portion having a slit-shaped outlet communicating with the lower end of the liquid pool portion; A prepreg manufacturing method in which a reinforcing fiber sheet is passed vertically downward through an application section provided with a The method of manufacturing a prepreg comprises the steps of: introducing the prepreg at intervals; and uniting the plurality of reinforcing fiber sheets inside the application section after introduction.

In addition, as a prepreg manufacturing method using a plurality of reinforcing fiber sheets, for example, Japanese Patent Application Laid-Open No. 2012-167230 discloses that a resin is applied to one side of a reinforcing fiber sheet, and then another reinforcing fiber sheet is laminated and impregnated. A method for manufacturing a prepreg is described. The manufacturing method is to arrange resin in the inner layer in advance so as not to form an unimpregnated portion even in a thick prepreg, and the object is to obtain a prepreg without an unimpregnated portion. Therefore, the technical idea is completely different from the method of obtaining the prepreg of the present invention described above. Moreover, even if the degree of impregnation is intentionally lowered in the method described in JP-A-2012-167230, the prepreg of the present invention cannot be obtained because the upper and lower surfaces of the prepreg become non-impregnated layers.

Hereinafter, the manufacturing method for obtaining the multilayer structure prepreg of the present invention will be described in detail with reference to FIG. FIG. 3 shows the case where the reinforcing fiber sheet is used as the UD base material. After obtaining a reinforcing fiber sheet 2 by arranging a plurality of reinforcing fibers 1 unwound from a creel 11 in one direction (the depth direction of the paper surface) by an arranging device 12, the reinforcing fiber sheet 2 is substantially applied to an application portion 20. , and the angle and position of incidence on the matrix resin 4 are adjusted by the pressing guide 14 , and guided to the application section 20 . After that, the matrix resin 4 is applied to both surfaces of each of the reinforcing fiber sheets 2 in the application section 20, and the matrix resin 4 is applied to both surfaces of each of the reinforcing fiber sheets 2, and the partially impregnated prepreg is partially impregnated. is formed. Then, the plurality of partially impregnated prepregs are combined into one in the vicinity of the narrowed portion in the application section 20, that is, the operation of overlapping the reinforcing fiber sheets so that they are integrated when pulled out from the narrowed portion. to obtain a multilayer structure prepreg 3. FIG. 3 exemplifies a case in which there are two reinforcing fiber sheets, but the number of reinforcing fiber sheets and the type of each reinforcing fiber sheet can be appropriately changed as required. Here, passing substantially vertically downward Z means that the angle α formed by the Z direction (vertical line) and the running direction of the reinforcing fiber sheet is within 20°.

At this time, at the upper end liquid surface of the liquid pool portion 22, the narrowest interval Ln (Fig. 5, the distance between the wall member 21a and the reinforcing fiber sheet 2) and the widest distance Lb (in the case of FIG. 5, the distance between the plurality of reinforcing fiber sheets 2) is 1≦Lb/Ln≦3. is preferably satisfied. This is because when the reinforcing fiber sheet 2 is run and the matrix resin 4 is applied, the matrix resin 4 is consumed and the liquid level at the upper end of the liquid pool 22 gradually decreases. If the ratio is too large, the liquid level at the upper end of each region of the liquid pool 22 divided by the reinforcing fiber sheet 2 will differ, and the liquid level at the upper end of each region of the liquid pool 22 divided by the reinforcing fiber sheet 2 will be different. Height difference occurs. When the liquid level difference between the front and back of the reinforcing fiber sheet 2 increases, the matrix resin 4 tries to flow from the higher liquid level to the lower liquid level, and the reinforcing fiber sheet 2 deforms in its thickness direction and contacts the wall member 21. Alternatively, when a UD base material is used as the reinforcing fiber sheet 2, there is a concern that the matrix resin 4 may flow into the gaps between the reinforcing fibers, disturbing the arrangement of the reinforcing fibers.

For example, when the ratio of Lb/Ln is too large in FIG. The matrix resin 4 tries to flow from the region (central region) sandwiched between the reinforcing fiber sheets 2 , and the reinforcing fiber sheets 2 are pressed against the wall surface member 21 . At this time, the reinforcing fiber sheet 2 rubs against the wall surface member 21 to generate a large amount of fluff, and in the worst case, the reinforcing fiber sheet 2 cannot run.

On the other hand, in FIG. 5, when the distance between the plurality of reinforcing fiber sheets 2 at the upper end liquid level of the liquid reservoir 22 is too narrow, the liquid level in the region sandwiched between the plurality of reinforcing fiber sheets 2 (central region) rises sharply. , and the matrix resin 4 is depleted, the matrix resin 4 tends to flow into the central region, which may also destabilize the running of the reinforcing fiber sheet 2 .

From the above, from the viewpoint of stabilizing the running of the reinforcing fiber sheet 2, in order to make the height of the liquid surface at the upper end of the liquid pool 22 uniform over the entire area, the distance between the wall surface of the liquid pool and the reinforcing fiber sheet 2 , the ratio of the intervals between the plurality of reinforcing fiber sheets 2 is preferably brought close to one. Specifically, the relationship between the narrowest interval Ln and the widest interval Lb preferably satisfies 1≦Lb/Ln≦3.

Here, in the application section 20 shown in FIG. 5, the gap between the wall surface member 21 and the reinforcing fiber sheet 2 at the upper end liquid surface of the liquid pool section 22 is narrower than the gap between the plurality of reinforcing fiber sheets. This is not the case as long as the relational expression is satisfied. For example, the spacing between the plurality of reinforcing fiber sheets 2 may be widened somewhat.

Further, the release sheet 5a is unwound from the release sheet supply device 16a, laminated on one side of the multi-layer structure prepreg 3, and wound into a roll shape by the winding device 17 via the take-up roll 15. In particular, even when the matrix resin 4 applied to the multilayer structure prepreg 3 reaches the take-up roll 15, part or all of the matrix resin 4 exists on the surface of the multilayer structure prepreg 3 and has high fluidity and adhesiveness. , the release sheet 5 a can prevent a part of the matrix resin 4 on the surface of the multilayer structure prepreg 3 from being transferred to the take-up roll 15 . Furthermore, adhesion between the multilayer structure prepregs 3 can be prevented, and handling in subsequent processes is facilitated. The release sheet is not particularly limited as long as it exhibits the above effects. Moreover, a release sheet 5b may be further laminated on another surface of the multi-layered prepreg 3, if necessary. The release sheets 5a and 5b may be of the same type, or may be of different types depending on the purpose.

Even when the reinforcing fiber sheet is a reinforcing fiber fabric, the same process can be adopted after the reinforcing fiber sheet 2 is formed in FIG. When using a reinforcing fiber fabric, the creel portion may be used as the reinforcing fiber fabric unwinding device.

In addition, FIG. 4 shows another preferred embodiment of this production method. Reinforcing fibers 414 are pulled out from a reinforcing fiber bobbin 412 hung on a creel 411 , passed through a direction changing guide 413 , and formed into a reinforcing fiber sheet 416 by a reinforcing fiber arranging device 415 . Although two sets of this process are shown in FIG. 4, three or more sets may be used. Although three reinforcing fiber bobbins in one set are described, in practice, the required number is multiplied according to the purpose. A plurality of reinforcing fiber sheets 416 are guided upward via direction changing rolls 419, then conveyed vertically downward via direction changing rolls 419, and preheated by preheating device 420 to a temperature equal to or higher than the matrix resin temperature in the coating section. be. Then, the pressing guide 412 adjusts the angle and position of incidence on the matrix resin and guides it to the application section 430 . After that, the matrix resin is applied and impregnated in the coating section 430, respectively, and combined into one sheet in the vicinity of the outlet in the coating section 430, so that the multilayer structure prepreg 471 can be formed. The multilayer structure prepreg 471 is laminated on the direction change roll 441 with the release sheet 446 unwound from the release sheet (upper) supply device 442, and is taken up by the high tension take-up S-shaped roll 449 which is the high tension take-up device. be done. At the same time, the release sheet unwound from the release sheet (lower) supply device 443 is laminated on the high-tension take-up S-shaped roll 449, and the release sheets are arranged on both upper and lower surfaces of the multilayer structure prepreg. Then, this is supplied to the add-on new device 450 , preheated by the hot plate 451 , and then impregnated using the heating nip rolls 452 . Thereafter, after being cooled by a cooling device 461 , the upper release sheet is peeled off via a take-up device 462 , and the multi-layer structure prepreg/release sheet is wound up into a roll shape by a winder 464 . The upper release sheet is taken up by the release sheet (upper) take-up device 463 .

Detailed preferred embodiments of the present manufacturing method are further described below.

<Formation of UD substrate>
When a UD base material is used as the reinforcing fiber sheet, a known method can be used for forming it, and there is no particular limitation. Forming the UD substrate by further arranging the fiber bundles 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. A reinforcing fiber arranging mechanism for arranging the reinforcing fiber bundles pulled out from the bobbin on the creel in an orderly manner to eliminate undesirable overlapping or folding of the reinforcing fiber bundles in the sheet-like reinforcing fiber bundles and eliminating gaps between the reinforcing fiber bundles. It is preferred to have As the reinforcing fiber arranging mechanism, a known roller or comb arranging device can be used. It is also useful from the viewpoint of reducing gaps between reinforcing fibers to stack a plurality of sheet-like reinforcing fiber bundles arranged in advance. 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.

<Smoothing of reinforcing fiber sheet>
In the manufacturing method, by increasing the surface smoothness of the reinforcing fiber sheet, it is possible to improve the uniformity of the application amount of the matrix resin at the applied portion. For this reason, it is preferable to guide the reinforcing fiber sheet to the application section after smoothing. 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 flow, 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. The smoothing device can be installed, for example, between the reinforcing fiber arrangement device 415 and the preheating device 420 in FIG.

<Expanding the width of the reinforcing fiber sheet>
Further, in the manufacturing method, it is also preferable from the viewpoint of efficiently manufacturing the thin-layer prepreg that the reinforcing fiber sheet is led to the liquid pool after being widened. Moreover, by multilayering the thin-layer prepreg, the layer thickness of the multilayer structure prepreg can be reduced, and the toughness and impact resistance of the FRP can be improved. The widening treatment method is not particularly limited, but examples include a method of imparting mechanical vibration and a method of widening the reinforcing fiber bundle by air flow. As a method of mechanically imparting vibration, there is a method of bringing a sheet-like reinforcing fiber bundle into contact with a vibrating roll, as described in Japanese Patent Application 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 sheet-like reinforcing fiber bundle is the X axis. It is also preferred to use a combination of rolls. 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 air flow, for example, SEN-I GAKKAISHI, vol. 64, P-262-267 (2008). The methods described can be used. The widening device can be installed, for example, between the reinforcing fiber arrangement device 415 and the preheating device 420 in FIG.

<Preheating of reinforcing fiber sheet>
Further, in the present invention, it is preferable to heat the reinforcing fiber sheet and then lead it to the liquid pooling portion, since the temperature drop of the matrix resin can be suppressed and the viscosity uniformity of the coating liquid can be improved. The reinforcing fiber sheet is preferably heated to a temperature close to the matrix resin temperature in the liquid pool. Heating means for this purpose include air heating, infrared heating, far infrared heating, laser heating, contact heating, heat medium heating steam, etc.) can be used. Among them, infrared heating is preferable because the device is simple and the sheet-shaped reinforcing fiber bundle 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 viscosity>
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 the coating liquid temperature at the liquid pool <Coating process>
Next, the step of applying the matrix resin to the reinforcing fiber sheet will be described in detail with reference to FIGS. Here, as the reinforcing fiber sheet 2, a UD base material is illustrated as an example. FIG. 5 is an enlarged detailed cross-sectional view of the application portion 20 in FIG. The application unit 20 includes wall surface members 21a and 21b facing each other with a predetermined gap D therebetween. , a slit-shaped constriction having a cross-sectional area smaller than the cross-sectional area of the upper surface of the liquid pool 22 (introduction side of the reinforcing fiber sheet 2) located below the liquid pool 22 (on the carrying-out side of the reinforcing fiber sheet 2). 23 are formed. In FIG. 5, the reinforcing fiber sheet 2 is described assuming a UD base material, but the reinforcing fibers are arranged in the depth direction of the paper surface.

In the application section 20, the reinforcing fiber sheet 2 introduced into the liquid pool section 22 travels downward while accompanying the matrix resin 4 around it. At this time, since the cross-sectional area of the liquid reservoir 22 decreases in the downward direction Z in the vertical direction, the accompanying matrix resin 4 is gradually compressed, and the pressure of the matrix resin 4 increases toward the bottom of the liquid reservoir 22. . 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, in the liquid reservoir 22, a circulation flow T is formed along the outer plane of the reinforcing fiber sheet 2 and the wall surfaces of the wall members 21a and 21b. As a result, even if the reinforcing fiber sheet 2 brings 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. Furthermore, as will be 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 2 is run at a high speed, the hydraulic pressure is further increased, so that the fluff removal effect is enhanced. As a result, it becomes possible to apply the matrix resin 4 at a high speed to the reinforcing fiber sheet 2, thereby greatly improving productivity.

In addition, the increased hydraulic pressure has the effect of facilitating impregnation of the matrix resin 4 into the inner layer portion of the reinforcing fiber sheet 2 . This is based on the property (Darcy's law) that when a porous body such as a reinforcing fiber bundle is impregnated with a coating liquid, the degree of impregnation increases with the pressure of the coating liquid. Also in this case, when the reinforcing fiber sheet 2 is run at a higher speed, the hydraulic pressure increases, so that the impregnation effect can be further enhanced. The matrix resin 4 is impregnated with air bubbles remaining in the inner layer of the reinforcing fiber sheet 2 by gas/liquid substitution. It is discharged in the orientation direction of the fibers (upper vertical direction). At this time, since the air bubbles are discharged without pushing away the impregnated matrix resin 4, there is an effect that the impregnation is not hindered. Also, some of the air bubbles are discharged from the surface of the reinforcing fiber sheet 2 into the liquid, but these air bubbles are also quickly removed vertically upward by the liquid pressure and buoyancy, so the liquid pool has a high impregnation effect. There is also an effect that air bubbles are efficiently discharged without staying at the lower part of 22 . These effects allow the reinforcing fiber sheet 2 to be efficiently impregnated with the matrix resin 4 . Since the degree of impregnation is governed by the liquid pressure and pressurization time of the matrix resin 4 in the application portion 20 as described by Darcy's Law, the degree of impregnation should not be 100% (unimpregnated portions should be left). d) The shape of the application portion 20 can be designed and the viscosity of the matrix resin can be adjusted. Then, since a plurality of prepreg sheets with non-impregnated portions are combined at the coating portion 20, it is possible to obtain the multilayer structure prepreg of the present invention.

In the manufacturing method of the present invention, not only can the multilayer structure prepreg described above be obtained, but depending on the condition setting, it is also possible to obtain a prepreg with a high degree of impregnation. It is explained below. In the application section 20 of FIG. 5 , a plurality of reinforcing fiber sheets 2 are introduced into the liquid pooling section 22 at intervals in the thickness direction, and then are united inside the coating section 20 and taken out, thereby forming the liquid pooling section 22 . and the constricted portion 23, the impregnation of the matrix resin 4 progresses in each of the supplied reinforcing fiber sheets 2. As shown in FIG. As a result, the prepreg 3 with a higher degree of impregnation with the matrix resin 4 can be obtained in the application section 20 of FIG. becomes possible. Here, in the application section 20 of FIG. 5, two reinforcing fiber sheets 2 are introduced into the liquid pool section 22 with an interval in the thickness direction thereof, but the number may be three or more. When obtaining a prepreg 3 with a constant thickness, the greater the number of reinforcing fiber sheets 2 introduced into the liquid reservoir 22, the thinner the thickness of each of the reinforcing fiber sheets introduced, and the shorter the required impregnation distance. , the degree of impregnation of the matrix resin 4 can be further increased. At this time, as the number of reinforcing fiber sheets 2 increases, the thickness of each reinforcing fiber sheet 2 becomes thinner. It is preferable that the prepreg 3 having a uniform thickness can be obtained by throwing the prepreg 3 into the liquid pool portion 22 after the prepreg 3 has been thinned.

Furthermore, due to the increased hydraulic pressure, the layered prepreg 3 formed by uniting the plurality of reinforcing fiber sheets 2 is automatically aligned in the center of the gap D, and the reinforcing fiber sheet 2 and/or the layered prepreg 3 are liquid. It also has the effect of suppressing the generation of fluff without directly rubbing against the wall surfaces of the pooled portion 22 and the constricted portion 23 . This is because when the reinforcing fiber sheet 2 and/or the layered prepreg 3 approaches either of the gaps D due to disturbance or the like, the matrix resin 4 is pushed into the narrower gap on the approaching side and is compressed. This is because the hydraulic pressure increases more on the side and pushes the reinforcing fiber sheet 2 and/or the layered prepreg 32 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. 5 and 7, the cross-sectional area is small because the length in the direction perpendicular to the pseudo-plane due to the reinforcing fiber sheet 2 is small, that is, the distance between the members is small. 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 2 and the flow control of the matrix resin 4, 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.

In addition, the total amount of the matrix resin 4 applied to the reinforcing fiber sheet 2 can be controlled by the gap D of the narrowed portion 23. ), the wall surface members 21a and 21b may be installed so that the gap D is widened.

FIG. 6 is a bottom view of the application unit 20 viewed from the direction of A in FIG. Side wall members 24a and 24b for preventing leakage of the matrix resin 4 from both ends of the reinforcing fiber sheet 2 in the direction in which the reinforcing fibers are arranged are provided in the application section 20. An outlet 25 of the constriction 23 is formed in the enclosed space. Here, the outlet 25 has a slit shape, and the cross-sectional aspect ratio (Y/D in FIG. 6) may be set according to the shape of the reinforcing fiber sheet 2 to which the matrix resin 4 is to be applied.

FIG. 7 is a cross-sectional view for explaining the structure of the inner layer portion of the coating section when the coating section 20 is viewed from direction B. As shown in FIG. In order to make the drawing easier to see, the wall member 21b is omitted, and the reinforcing fibers of the reinforcing fiber sheet 2 are drawn as if they are arranged with gaps between them. Arrangement is preferable from the viewpoint of the quality of the multilayer structure prepreg 3 and the mechanical properties of the FRP.

FIG. 8 shows the flow of the coating liquid 2 in the gap 26. As shown in FIG. If the gap 26 is large, a vortex flow is generated in the R direction in the matrix resin. This vortex flow R becomes an outward flow (Ra) at the lower portion of the liquid pool 22, and tears the reinforcing fiber sheet 2 (if the reinforcing fiber sheet 2 is a UD base material, cracking of the reinforcing fiber bundle may occur). In some cases, the spacing between the reinforcing fibers may be widened, which may cause uneven arrangement of the reinforcing fibers when the multilayer structure prepreg 3 is formed. On the other hand, in the upper portion of the liquid pool portion 22, since the flow (Rb) is directed inward, the reinforcing fiber sheet 2 is compressed in the width direction, and the end portion may be broken. In a device that applies a coating liquid to both sides of a film, as typified by Patent Document 2 (Japanese Patent No. 3252278), even if such a vortex flow occurs in the gap 26, the quality will be less affected. was not done.

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 is configured to satisfy the following relationship with the width W of the sheet-shaped reinforcing fiber bundle measured directly below the constricted portion 23. is preferred.
L≦W+10 (mm).

As a result, the generation of eddy currents at the ends is suppressed, cracking and edge folding of the reinforcing fiber sheet 2 can be suppressed, and the reinforcing fibers are uniformly arranged over the entire width (W) of the multilayer structure prepreg 3, resulting in a high-quality prepreg. A multilayer structure prepreg 3 with high stability can be obtained. As a result, not only the grade and quality of the prepreg can be improved, but also the mechanical properties and quality of the FRP obtained by using the prepreg can be improved. If the relationship between L and W is more preferably L≦W+2 (mm), it is possible to further suppress cracking and edge folding of the reinforcing fiber sheet.

Moreover, 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 multilayer structure prepreg 3 .

Note that this width regulation is preferably performed at least at the lower portion of the liquid pool portion 22 (the position of G in FIG. 7) from the viewpoint of suppressing the generation of the eddy flow R due to the high liquid pressure in the lower portion of the liquid pool portion 22 . 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 sheet-like reinforcing fiber bundle is prevented from cracking and breaking at the ends. It is possible to suppress it almost completely.

From the viewpoint of suppressing the vortex flow in the gap 26, the width regulation may be applied only to the liquid pool portion 22. However, if the narrowed portion 23 is also subjected to the width regulation, excessive matrix resin 4 is applied to the side surface of the multi-layer structure prepreg 3. It is preferable from the viewpoint of suppressing that it is done.

<Gap between reinforcing fiber sheets>
FIG. 15 is a detailed sectional view of the application section 20 same as that of FIG. In the application section 20 of FIG. 15, a plurality of reinforcing fiber sheets 2 are thrown into the liquid pool section 22 with intervals in the thickness direction. The incident angle and position of the reinforcing fiber sheet 2 are adjusted by the pressing guide 14 . At this time, at the upper end liquid surface of the liquid pool portion 22, the narrowest interval Ln ( In the case of FIG. 15, the distance between the wall member 21 and the reinforcing fiber sheet 2) and the widest distance Lb (in the case of FIG. 15, the distance between the plurality of reinforcing fiber sheets 2) is 1≦Lb/Ln≦3. preferably fulfilled. This is because when the reinforcing fiber sheet 2 is run and the matrix resin 4 is applied, the matrix resin 4 is consumed and the liquid level at the upper end of the liquid pool 22 gradually decreases. If the ratio is too large, the liquid level at the upper end of each region of the liquid pool 22 divided by the reinforcing fiber sheet 2 will differ, and the liquid level at the upper end of each region of the liquid pool 22 divided by the reinforcing fiber sheet 2 will be different. Height difference occurs. When the liquid level difference between the front and back of the reinforcing fiber sheet 2 increases, the matrix resin 4 tries to flow from the higher liquid level to the lower liquid level, and the reinforcing fiber sheet 2 deforms in its thickness direction and contacts the wall member 21. Alternatively, when a UD base material is used as the reinforcing fiber sheet 2, there is a concern that the matrix resin 4 may flow into the gaps between the reinforcing fibers, disturbing the arrangement of the reinforcing fibers.

For example, when the ratio of Lb/Ln is too large in FIG. The matrix resin 4 tries to flow from the region (central region) sandwiched between the reinforcing fiber sheets 2 , and the reinforcing fiber sheets 2 are pressed against the wall surface member 21 . At this time, the reinforcing fiber sheet 2 rubs against the wall surface member 21 to generate a large amount of fluff, and in the worst case, the reinforcing fiber sheet 2 cannot run.

On the contrary, in FIG. 15, when the distance between the plurality of reinforcing fiber sheets 2 at the upper end liquid level of the liquid pool 22 is too narrow, the liquid level in the region (central region) sandwiched between the plurality of reinforcing fiber sheets 2 sharply rises. and the matrix resin 4 is depleted, the matrix resin 4 applied to the gaps between the plurality of reinforcing fiber sheets 2 becomes insufficient, and the impregnation from the inside of the reinforcing fiber sheet 2 at the application portion 20 does not sufficiently proceed, and the prepreg There is a concern that 3 may result in poor impregnation.

From the above, from the viewpoint of stabilizing the running of the reinforcing fiber sheet 2 and improving the degree of impregnation of the matrix resin into the prepreg 3, the liquid It is preferable to bring the ratio of the distance between the wall surface of the pool and the reinforcing fiber sheet 2 to the distance between the plurality of reinforcing fiber sheets 2 close to one. Specifically, the relationship between the narrowest interval Ln and the widest interval Lb preferably satisfies 1≦Lb/Ln≦3.

Here, in the application section 20 shown in FIG. 15, the gap between the wall surface member 21 and the reinforcing fiber sheet 2 at the upper end liquid surface of the liquid pool section 22 is narrower than the gap between the plurality of reinforcing fiber sheets. This is not the case as long as the dimensional relationship is satisfied. For example, the distance between the plurality of reinforcing fiber sheets 2 may be widened.

<Unification of reinforcing fiber sheets>
15 shows an example in which a plurality of reinforcing fiber sheets 2 are united in the vicinity of the boundary between the liquid pool portion 22 and the constricted portion 23. may be performed anywhere inside the application unit 20 . For example, as in the application portion 20a of FIG. 16, a submerged guide 18 may be provided inside the liquid pool portion 22, and the plurality of reinforcing fiber sheets 2 may be united in the middle of the liquid pool portion 22. However, if the reinforcing fiber sheets 2 are united near the upper liquid surface of the liquid reservoir 22, the matrix resin 4 in the region sandwiched between the plurality of reinforcing fiber sheets 2 is small, and the above <interval between the reinforcing fiber sheets> As described above, there is a concern that the matrix resin 4 applied to the gaps between the plurality of reinforcing fiber sheets 2 is insufficient, impregnation from the inside of the reinforcing fiber sheet 2 does not proceed sufficiently, and impregnation of the prepreg 3 becomes defective. Therefore, it is preferable to combine the reinforcing fiber sheets 2 below the center of the liquid reservoir 22 . When the submerged guide 18 is not used, the plurality of reinforcing fiber sheets 2 are united at the portion where the cross-sectional area of the liquid pool 22 is the narrowest, that is, near the boundary between the liquid pool 22 and the narrowed portion 23. become.

<Width regulation mechanism>
In the above description, the side wall members 24a and 24b are responsible for width regulation, but as shown in FIG. 9, width regulation mechanisms 27a and 27b are provided between the side wall members 24a and 24b. It can also be regulated. 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 narrowed portion in FIG. and more preferably L2≦W+2 (mm). In addition, it is preferable to adjust the lower limit of L2 to W−5 (mm) or more from the viewpoint of improving the uniformity of the width direction dimension of the prepreg 3 . The shape and material of the width regulating mechanism are not particularly limited, but a plate-shaped bush is convenient and preferable. On the other hand, it is preferable that the width regulating mechanism has a shape that conforms to the internal shape of the coating portion from the intermediate portion to the lower portion, because it is possible to suppress the retention of the coating liquid in the liquid pool portion and to suppress deterioration of the coating liquid. From this point of view, it is preferable that the width regulating mechanism is inserted up to the narrowed portion 23 as shown in FIG. 9(b).

Moreover, it is preferable that the width regulating mechanisms 27 are provided at both ends in the width direction of the plurality of reinforcing fiber sheets 2 so as to be along the traveling path of the reinforcing fiber sheets 2 . For example, when a plurality of reinforcing fiber sheets 2 are run in a V-shape as shown in FIG. 3, it is preferable that the width regulating mechanism is V-shaped as shown in FIG. 9(d).

17 is a view of the application section 20 of FIG. 5 as seen from the Z direction of FIG. 3, similar to FIG. indicates In the vicinity of the liquid surface at the upper end of the liquid pool 22, as shown in FIG. 17, the width regulating mechanism 27 is divided from each other, that is, the width regulating mechanism 27 is divided between the plurality of reinforcing fiber sheets introduced into the coating section. It is preferable to provide the width regulating mechanism so that there is a place where the mechanism does not exist, and to provide a gap from the wall surface members 21a and 21b or the side plate members 24a and 24b. Specifically, the interval Lx between the wall surface member 21 and the width regulating mechanism 27 or the interval Ly between the side plate member 24 and the width regulating mechanism 27 is preferably 10 mm or more. By not obstructing the horizontal flow F of the matrix resin 4, the matrix resin 4 spreads over the entire region of the liquid reservoir 22, and the liquid level is increased as described in the <Gap between reinforcing fiber sheets> section. This is for the purpose of reducing the height difference, stabilizing the running of the reinforcing fiber sheet 2, and improving the degree of impregnation of the prepreg 3 with the matrix resin.

Furthermore, it is preferable that the dimension E of the width regulating mechanism 27 in the thickness direction of the reinforcing fiber sheet 2 is set to 10 mm or more at the upper end liquid surface of the liquid pool portion 22 . More preferably, it is 20 mm or more. This is to prevent the ends of the reinforcing fiber sheet 2 from bending or shaking by preventing the horizontal flow F from directly hitting the ends of the reinforcing fiber sheet 2 in the width direction.

9 shows an example of a plate-shaped bush as the width regulating mechanism, but in FIG. shows an example of FIG. 9(b) shows an example in which L2 is constant from the surface of the coating liquid to the exit of the narrowed portion, but 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 plate-shaped bush can be fixed even if high hydraulic pressure is applied. It is possible to suppress fluctuations in the restricted width due to deformation of the . 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 manufacturing method of the present invention, the cross-sectional area in the liquid reservoir 22 continuously decreases in the Z direction, so that the liquid pressure in the running direction of the reinforcing fiber sheet 2 can be increased. It is important to note that the continuous decrease in the cross-sectional area in the running direction of the sheet-like reinforcing fiber bundle 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. 10-13.

FIG. 10 is a detailed cross-sectional view of the 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. 10, 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 accompanied by the reinforcing fiber sheet is compressed in the region 22a where the cross-sectional area of the liquid pool 22 continuously decreases, and the liquid pressure generated in the lower part of the liquid pool 22 is reduced. can be sufficiently increased. As a result, it is possible to obtain the effect of preventing fluff from clogging the constricted portion 23 by the hydraulic pressure and impregnating the reinforcing fiber sheet with the matrix resin by the hydraulic pressure.

Here, when the region 22a in which the cross-sectional area of the liquid pooling portion 22 continuously decreases is tapered like the application portion 20 in FIG. 5 or the application 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 can be enhanced in the region 22a (tapered portion) where the cross-sectional area of the liquid reservoir portion 22 continuously decreases, and a high liquid pressure can be easily obtained.

FIG. 11 is a detailed cross-sectional view of an application portion 20c of another embodiment than that of FIG. 10 except that wall surface members 21e and 21f forming the liquid reservoir 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. 11, 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 coating liquid 2 can be further enhanced.

FIG. 12 is a detailed cross-sectional view of an application portion 20d of another embodiment different from that of FIG. 10 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 a shape as shown in FIG. 12, the depth B of the liquid pooling portion 22 can be expanded and the coating liquid 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 coating liquid 2 cannot be continuously supplied to the coating portion 20d, the matrix resin can be continuously applied to the reinforcing fiber sheet for a long time, and the productivity of the multilayer structure prepreg is further improved.

FIG. 13 is a detailed cross-sectional view of an application section 20e of another embodiment from that of FIG. 10 except that wall surface members 21i and 21j forming the liquid reservoir 22 are shaped like trumpet (curved). In the application portion 20b of FIG. 10, the region 22a in which the cross-sectional area of the liquid pool portion 22 continuously decreases is tapered (straight), but is not limited to this. 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 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. 14 is a detailed cross-sectional view of another form of the application unit 30. As shown in FIG. 10 to 13, the liquid reservoir 32 in FIG. 14 does not include a region in which the cross-sectional area continuously decreases in the downward vertical direction Z, and the cross-sectional area is discontinuous and sharply It is a decreasing configuration. For this reason, it is preferable to avoid reinforcing fiber sheets and multi-layered prepregs because they are easily clogged.

<Travel mechanism>
A known roller or the like can be suitably used as a traveling mechanism for conveying the reinforcing fiber sheet or the multilayer structure prepreg of the present invention. In the present invention, since the reinforcing fiber sheet is conveyed substantially vertically downward, it is preferable to arrange rollers above and below with the application section interposed therebetween.

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, in the process of transporting a sheet-shaped integrated body, which is a laminate of a multilayer structure prepreg and a release sheet, if there is a bent portion, wrinkles may occur due to the difference in the peripheral length between the inner layer and the outer layer. It is preferable that the traveling route of the vehicle is also 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 dispose a high-tension take-up device for pulling out the multilayer structure 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 application part, and in order to overcome this and pull out the multilayer structure prepreg, a high take-up tension must be generated downstream of the process. This is because it is preferable. Nip rolls, S-shaped rolls, etc. can be used as the high-tension take-up device, but in any case, by increasing the frictional force between the roll and the multilayer structure prepreg, it is possible to prevent slippage and enable stable running. can be done. For this purpose, it is preferable to apply a material having a high coefficient of friction to the surface of the roll, or to increase the nip pressure or the pressing pressure of the multi-layer structure 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 by the production method of the present invention, a release sheet supply device and a winder can be used as appropriate, and known ones 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. The release sheet is bonded to either or both of the upper and lower surfaces of the prepreg (or multilayer prepreg). Incidentally, joining means "laminate", and needless to say, the release sheet can be peeled off when the prepreg is used.

<Additional impregnation>
In order to adjust the degree of impregnation to a desired degree, it is also possible to combine means for further increasing the degree of impregnation using an impregnation device after application of the matrix resin. 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 a reinforcing fiber sheet and a resin with a hot plate to sufficiently soften the resin on the sheet-like carbon fiber bundle, Impregnation can be advanced by using a pressurizing device 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. The "S-wrap roll" is referred to herein simply as the "S-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 and the degree of impregnation is increased, 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, it is possible to improve the impregnation efficiency by applying ultrasonic waves to the prepreg before impregnation and rapidly raising the temperature of the prepreg. be. Further, as described in Japanese Patent Application Laid-Open No. 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 multilayer structure 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 impregnation is not completed, it is possible to omit or simplify a heating device such as a hot plate for reheating the multilayer structure prepreg, and to greatly simplify and downsize 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, but compared to a normal impregnation device, the roll diameter, set pressure, and contact length between the prepreg and the roll can be reduced, making the device more compact. Not only can it be possible, but also power consumption can be reduced, which is preferable.

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

<Width of prepreg>
Moreover, there is no particular limitation on the method of obtaining a prepreg of a desired width, 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.

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. .

In the present invention, the impregnation rate of the coating liquid is desirably 10% or more. The impregnation rate of the coating liquid can be confirmed by tearing the collected sheet-like reinforcing fiber bundle impregnated with the coating liquid and visually inspecting the inner layer, and can be evaluated more quantitatively by, for example, a peeling method. It is possible. The impregnation rate of the coating liquid by the peeling method can be measured as follows. That is, the sampled sheet-shaped reinforcing fiber bundle impregnated with the coating liquid is sandwiched with an adhesive tape and peeled off to separate the reinforcing fibers to which the coating liquid is adhered and the reinforcing fibers to which the coating liquid is not adhered. Then, the ratio of the mass of the reinforcing fibers to which the coating liquid is adhered to the total mass of the supplied sheet-like reinforcing fiber bundle can be used as the impregnation rate of the coating liquid by the peeling method.

<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, since most of the cut ends become a release sheet, it is possible to reduce fluff of the matrix resin and reinforcing fibers adhering to the slit cutter blade, and there is also the advantage that the cleaning cycle of the slit cutter blade can be extended. .

<Matrix resin supply mechanism>
In this production method, the matrix resin is stored in the coating portion, but it is preferable to replenish the matrix resin as appropriate 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, the weight of the coating liquid can be used as a driving force from a tank in which the coating liquid is stored, or the coating liquid can be continuously supplied 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 depending on the properties of the coating liquid. 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 coating liquid in accordance with the coating amount so that the liquid surface of the upper portion of the coating liquid to be coated 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.

<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 coating amount can be estimated by measuring the thickness of the reinforcing fiber sheet and the thickness of the multilayer structure 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. 5) 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. can be done. It is also preferable to perform on-line defect monitoring using infrared rays, near-infrared rays, cameras (image analysis), and the like.

<Production of prepreg>
(1) Prepreg Manufacturing Apparatus In Examples 1 to 5, the coating section of the coating section 20c type shown in FIG. 11 was used, and the pressing guide 14 having the configuration shown in FIG. 18 was installed. As a prepreg manufacturing apparatus, an apparatus having the configuration shown in FIG. 4 (illustration of the matrix resin supply section is omitted) was used.

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. The liquid reservoir portion was tapered in two stages, with the upper taper having an opening angle of 17°, the taper height (ie, H) being 100 mm, and the lower taper having an opening angle of 7°. In addition, as a width control mechanism, a plate-like bush matching the shape of the inside of the coating part as shown in FIG. 9 is provided. did. 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 0.2 mm. In this case, the exit slit has an aspect ratio of 1,500. In addition, the plate-like bushing used at this time was Y-shaped so that the matrix resin could flow into the central region from the space between the two reinforcing fiber sheets. In addition, in order to prevent the application liquid from leaking from the outlet of the narrowed portion, the lower surface of the outlet of the narrowed portion was closed outside the bush. Further, in order to heat the coating liquid, plate heaters were attached to the outer peripheries of the wall surface members 21e and 21f and the side plate members 24a and 24b, and the temperature and viscosity of the matrix resin were adjusted while measuring the temperature with thermocouples.

In Examples 6 to 12 and Comparative Example 5, the prepreg manufacturing apparatus shown in FIG. 4 (illustration of the matrix resin supply section is omitted) was used, and the application section used the pressing guide 14 and the application section 20f shown in FIG. Examples 6 to 12) or the pressing guide 14 and the application portion 40 having the configuration shown in FIG. 19 (Comparative Example 5) were used. 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. The liquid pool portion was tapered in two steps, the upper taper having an opening angle of 17°, the lower taper having an opening angle of 7°, and the total height of the tapers (that is, H) was 100 mm. The width Y of the constricted portion was 300 mm, and the gap D of the constricted portion was 0.2 mm. In this case, the exit slit has an aspect ratio of 1,500. Further, in order to heat the matrix resin, plate heaters were attached to the outer peripheries of the wall surface members 21e and 21f and the side plate members 24a and 24b, and the temperature of the matrix resin was maintained at 90°C while measuring the temperature with thermocouples. Table 2 is a table summarizing the experimental results of fabricating CFRP prepregs in Examples 6 to 8 and Comparative Example 5 and evaluating running stability and degree of impregnation. As a condition common to Examples 6 to 8 and Comparative Example 5, no width regulating mechanism was used.

(2) Reinforcing fiber sheet As the reinforcing fiber sheet, two UD base materials in which carbon fibers (Torayca T800S (24K), manufactured by Toray) are arranged are formed, and a thermosetting epoxy resin composition described later is used as a matrix resin. A multi-layer prepreg for CFRP was produced using the apparatus. Also, the number of reinforcing fiber bobbins 412 was adjusted according to the prepreg to be produced, but the number was set to 29 bobbins per reinforcing fiber sheet unless otherwise specified.

(3) Prepreg manufacturing method Reinforcing fibers were pulled out from a plurality of reinforcing fiber bobbins hung on a creel, two reinforcing fiber sheets were formed by a reinforcing fiber arranging device, and guided upward by a direction change roll. After that, it was conveyed vertically downward via direction changing rolls and preheated to the temperature of the matrix resin in the coating section or higher by a preheating device. Then, using a pressing guide, the incident angle α and the incident position were adjusted so that the two reinforcing fiber sheets were symmetrical, and at this time, Lb / Ln was guided to the application part so that 2 (however, If there is a special note, it was adjusted to that Lb/Ln). After that, a matrix resin was applied and impregnated in each of the coating portions, and the prepregs were combined into one sheet in the vicinity of the constricted portion in the coating portion to form a multi-layer structure prepreg. The multi-layered prepreg was laminated on the turning roll with a release sheet unwound from a release sheet (upper) feeder and taken up by a high tension take-up S-roll. At the same time, the release sheet unwound from the release sheet (lower) supply device was laminated on the high-tension take-up S-shaped roll, and the release sheets were arranged on both upper and lower surfaces of the multilayer structure prepreg. Then, this was supplied to a new impregnation device, preheated by a hot plate, and then subjected to additional impregnation using a heating nip roll. Thereafter, after being cooled by a cooling device, the release sheet on the upper side was peeled off through a take-up device, and the multilayer structure prepreg/release sheet was wound up into a roll shape by a winder. However, in Comparative Example 5, the prepreg was produced by introducing the superimposed reinforcing fiber sheets into the coating portion.

(4) Matrix resin Thermosetting epoxy resin composition 1 (matrix resin A):
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 1 was measured using ARES-G2 manufactured by TA Instruments at a measurement frequency of 0.5 Hz and a heating rate of 1.5°C/min. was 15 Pa·s at 105°C and 4 Pa·s at 105°C.

Thermosetting epoxy resin composition 2 (matrix resin B):
A mixture of epoxy resin (aromatic amine type epoxy resin + bisphenol type epoxy resin), curing agent (diaminodiphenylsulfone), polyethersulfone, as polymer particles, "particles described in Examples of JP-A-2011-162619 3” (Tg=150° C.) was added so as to be 12% by mass when the mass of the entire resin composition was 100% by mass.

The viscosity of this thermosetting epoxy resin 2 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. was 32 Pa·s at 105°C and 10 Pa·s at 105°C.

<Prepreg evaluation method>
(1) Evaluation of prepreg layer structure The prepreg was frozen at −18° C. in a freezer, removed from the freezer, and then quickly cut at room temperature using a cutter to prepare a prepreg cross section in the thickness direction. This sample was observed using a scanning electron microscope, VHX-5000 manufactured by Keyence Corporation.

(2) Matrix resin impregnation degree of prepreg (water absorption rate of prepreg)
The degree of impregnation in Examples 1 to 5 and Comparative Examples 1 to 4 can be evaluated from the water absorption rate of the prepreg due to capillary action. , one side of which is 5 mm, was calculated from the change in mass when immersed in water for 5 minutes. The lower the water absorption, the higher the degree of impregnation.

The degree of impregnation of the prepregs of Examples 6 to 12 and Comparative Example 5 was quantitatively evaluated by a peeling method. The degree of impregnation of the coating liquid by the peeling method was 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 was adhered to the mass of the entire reinforcing fiber sheet put in was obtained as the degree of impregnation of the matrix resin by the peeling method.

(3) Shape retention of prepreg A. Adhesion between prepreg and release paper in the prepreg manufacturing process In the transport process of prepreg and release paper in the prepreg manufacturing process, "Good" means that there are no peelings of the release paper per 400 m of running, and "Fair" means that the peeling occurs only once. ", and two times or more were evaluated as "Bad".

B. Shape retention of prepreg roll A prepreg with release paper laminated on one side was rolled up into a 400 m roll shape, and this roll was placed vertically and left at 20°C and 65% RH for 24 hours. "Good" when the length in the direction (peeling distance) is less than 5 cm, "Fair" when the peeling distance is 5 cm or more and less than 30 cm, and "Bad" when the peeling distance is 30 cm or more.

In addition, the non-impregnated prepreg layer, that is, the prepreg peel distance in the dry reinforcing fiber or void portion of less than 5 cm is "Good", the peel distance is 5 cm or more and less than 30 cm is "Fair", and the peel distance is 30 cm or more. The one with 1 was set as "Bad".

C. Shape retention of prepreg in prepreg lamination process When 16 sheets of 30 cm square prepreg (using UD base material) are laminated in one direction, the unimpregnated layer of prepreg, that is, dry reinforcing fibers and voids are evaluated for peeling and displacement. did. One layer or less of peeling or displacement was evaluated as "Good", two or three layers of peeling or displacement were evaluated as "Fair", and four or more layers of peeling or displacement were evaluated as "Bad".

D. When cutting prepreg into 16 sheets of 30 cm square, if there are 2 or less reinforced fiber fluffs on the cut surface, it is rated as "Good", and if it is in 3 to 4 places. was set as "Fair", and those with 5 or more points were set as "Bad".

(4) Vacuum pressure formability After 16 sheets of 30 cm square prepreg (using UD base material) were laminated in one direction to form a prepreg laminate, 100 μm thick PTFE films were placed on both surfaces of the prepreg laminate. , was placed on an aluminum plate having a thickness of 10 mm and covered with a polyamide film. Furthermore, in an environment of 25° C., the degree of vacuum around the prepreg laminate was set to 3 kPa, and the laminate was left for 3 hours to remove volatile matter. After that, while maintaining the degree of vacuum at 3 kPa, the temperature was raised to 120° C. at a rate of temperature rise of 1.5° C./min and held for 180 minutes. Thereafter, the temperature was further raised to 180° C. at a rate of temperature increase of 1.5° C./min and held for 120 minutes to cure the matrix resin and obtain CFRP.

Three sample pieces of 1 cm in length and 1 cm in width were cut out from this CFRP, and after polishing the cross section, the upper and lower surfaces of the CFRP were observed with an optical microscope using a 50x lens so that the upper and lower surfaces of the CFRP were within the field of view, and an image was obtained. . From this obtained image, the ratio of the void area to the total cross-sectional area was calculated, and the void ratio of each image was calculated. The same operation was performed at 3 points for each sample piece, and the void ratio was calculated at a total of 9 points, and the average value was taken as the void ratio for each evaluation level. An average void fraction of less than 1% was rated as "Good", an average void ratio of 1% or more and less than 2% was rated as "Fair", and an average void rate of 2% or more was rated as "Bad".

(5) Process stability of the prepreg manufacturing process In order to evaluate the running stability of the reinforcing fiber sheet in the application part in each example or comparative example, the state of the reinforcing fiber sheet near the upper liquid surface of the liquid pool, the reinforcing fiber The difference in liquid level between the front and back of the sheet and the appearance of fluff circulating in the liquid pool were observed. In the vicinity of the liquid level at the upper end of the liquid pool, a liquid level difference occurs between the front and back of the reinforcing fiber sheet, and the flow of the matrix resin causes cracking of the fiber bundles over the entire width of the reinforcing fiber sheet. "Good" indicates that there are no cracks in the fiber bundle, but fluff circulates in the liquid pool. A sample with a difference in surface height was evaluated as "Very Good", and a sample with a difference in liquid surface height of less than 5 mm without cracking of the fiber bundle or fluff in the liquid pool was evaluated as "Excellent".

In addition, when the end of the obtained prepreg has a break or crack in the fiber bundle (the region where the reinforcing fiber does not exist in the prepreg and only the matrix resin exists), the quality of the end is "Fair", and the fiber bundle is broken. "Good" indicates that the thickness of the reinforcing fiber is uneven at the end of the obtained prepreg, although no cracks or cracks are observed. "

[Example 1]
Thermosetting epoxy resin composition 1 (matrix resin A) was used as the matrix resin, and a multilayer structure prepreg having a width of 300 mm was produced with the distance L2 between the lower ends of each prepreg being 300 mm as the width regulating mechanism. However, the hot plates and heating nip rolls of the additional impregnation device were not used here, and no additional impregnation was performed. The temperature of the coating liquid in the liquid reservoir was set to 90° C. (equivalent to 15 Pa·s). Moreover, the running speed of the reinforcing fiber sheet and the multilayer structure prepreg was set to 10 m/min.

When the cross section of the obtained multilayer structure prepreg was observed with an SEM, it had a layer structure of impregnated layer/non-impregnated layer/impregnated layer/non-impregnated layer/impregnated layer, and the maximum value of the non-impregnated portion was 54%. Met. Moreover, the cross-sectional area of voids and dry reinforcing fiber aggregates contained in the non-impregnated layer was 320 μm ² at maximum. As a result, the multilayer prepreg obtained as shown in Table 1 exhibited excellent handleability.

In addition, since the reinforcing fiber sheet used was a UD base material arranged according to the same standard, the arrangement of the reinforcing fibers in the planar direction in the obtained multilayer structure prepreg was substantially the same throughout the thickness direction of the prepreg. Met.

In addition, since this multi-layered prepreg has an unimpregnated layer, voids in the vacuum pressure moldability were sufficiently small. Moreover, the CFRP obtained by this vacuum pressure molding 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.

[Example 2]
A multilayer structure prepreg was produced in the same manner as in Example 1, except that thermosetting epoxy resin 2 (matrix resin B) was used as the matrix resin and the temperature of the coating liquid in the liquid pool was set to 105°C. After the experiment, the resin remaining between the width regulating devices of the coating portion was sampled, dissolved with a solvent, filtered to separate the polymer particles, and the mass was measured. According to this, it was calculated that the percentage of the polymer particles passing through the coating portion was 99% or more, so it was determined that most of the polymer particles passed through the coating portion and were coated on the prepreg.

When the cross section of the obtained multilayer structure prepreg was observed with an SEM, it had a layer structure of impregnated layer/non-impregnated layer/impregnated layer/non-impregnated layer/impregnated layer, and the maximum value of the non-impregnated portion was 56%. Met. Moreover, the cross-sectional area of voids and dry reinforcing fiber aggregates contained in the non-impregnated layer was 350 μm ² at maximum. As a result, the multilayer prepreg obtained as shown in Table 1 exhibited excellent handleability.

In addition, since the reinforcing fiber sheet used was a UD base material arranged according to the same standard, the arrangement of the reinforcing fibers in the planar direction in the obtained multilayer structure prepreg was substantially over the entire thickness direction of the prepreg. were identical.

[Example 3]
The multilayer structure prepreg was impregnated with the matrix resin by the method described in Example 2, except that the additional impregnation device equipped with a hot plate and a heating nip roll was operated and used, followed by introducing it to the additional impregnation device, Additional impregnation was performed in-line with reference to JP-A-2011-132389. The obtained prepreg had a water absorption rate of 4%. When the cross section of the obtained multilayer structure prepreg was observed with an SEM, it had a layer structure of impregnated layer/non-impregnated layer/impregnated layer/non-impregnated layer/impregnated layer, and the maximum value of the non-impregnated portion was 20%. Met. Moreover, the cross-sectional area of voids and dry reinforcing fiber aggregates contained in the non-impregnated layer was 100 μm ² at maximum. As a result, the multilayer prepreg obtained as shown in Table 1 exhibited excellent handleability. In addition, the number of voids in the vacuum pressure moldability of this multi-layered prepreg was small.

[Comparative Examples 1 and 2]
With reference to the description of Patent Document 2, a matrix resin film was prepared by applying the matrix resin A onto a release paper, and a 30 cm wide UD corresponding to a stack of two reinforcing fiber sheets used in Example 1 was formed. A prepreg was prepared by sandwiching the substrate from both sides and impregnating it with an impregnator to change the degree of impregnation.

In Comparative Example 1, since the matrix resin was completely impregnated, no non-impregnated layer was formed.

In Comparative Example 2, a prepreg having a three-layer structure of impregnated layer/non-impregnated layer/impregnated layer was obtained, but since the central impregnated layer was thick, the non-impregnated layer peeled off or shifted, resulting in poor handleability. . Also, although the degree of impregnation was varied, it was not possible to achieve both vacuum pressure moldability and handleability.

[Comparative Example 3]
With reference to Japanese Unexamined Patent Application Publication No. 2012-167230, the matrix resin A used in Example 1 was applied onto the reinforcing fiber sheet used in Example 1 using a die coater. The laminated reinforcing fiber sheets were laminated and sandwiched between release papers from the upper and lower surfaces. Then, this was impregnated using an impregnator, the degree of impregnation was adjusted, and a non-impregnated portion was left to prepare a three-layer structure prepreg of non-impregnated layer/impregnated layer/non-impregnated layer. However, since the prepreg surface is an unimpregnated layer, there is a problem that the prepreg is easily peeled off from the release paper. In addition, since non-impregnated layers of prepreg are laminated when laminating prepregs, the adhesion between prepregs is poor, and peeling and shifting of prepregs occur, resulting in poor handleability.

[Examples 4 and 5 and Comparative Example 4]
The sheet-like integral body composed of the prepreg/release paper obtained in Examples 1 and 3 and Comparative Example 1 was slit to obtain a prepreg tape with a width of 7 mm. The prepreg tapes of Examples 4 (multilayer structure prepreg of Example 1) and 5 (multilayer structure prepreg of Example 3) generate less fluff at the slitter than Comparative Example 4 (prepreg of Comparative Example 1). rice field.

[Example 6]
Using the pressing guide 14 and the application portion 20f shown in FIG. 18, two reinforcing fiber sheets are put into the liquid pool portion 22 with a gap in the thickness direction, and the matrix resin is applied and impregnated. was united inside to produce one prepreg. Using the pressing guide 14, the reinforcing fiber sheet was adjusted so that the angle of incidence and the position of the liquid on the liquid reservoir 22 were bilaterally symmetrical. At this time, the distance between the wall surface member 21 and the reinforcing fiber sheet 2 was set to 20 mm, and the distance between the reinforcing fiber sheets 21 was set to 100 mm (Lb/Ln=5).

Observation of the state of the applied part revealed that the liquid level in the area sandwiched between the wall member and the reinforcing fiber sheet dropped rapidly, creating a liquid level difference of 20 mm or more between the front and back of the reinforcing fiber sheet. Cracking of the fiber bundle was observed over the entire width of the reinforcing fiber sheet due to the inflow (running stability "Fair"). The impregnation degree of the matrix resin of the obtained prepreg was 85%.

[Comparative Example 5]
A prepreg was produced using the presser guide 14 and the coating section 40 shown in FIG. 19 having a form different from the present invention. As a difference from Example 6, the position of the pressing guide 14 and the running path of the reinforcing fiber sheet 2 were adjusted, and the reinforcing fiber sheets were united and thrown into the liquid pool portion 22 before being thrown into the application portion 40 . The impregnation degree of the matrix resin of the obtained prepreg was 60%.

[Example 7]
A prepreg was produced using the pressing guide 14 and the application portion 20f shown in FIG. 18 according to the present invention. The position of the pressing guide 14 was adjusted from Example 6 to set the distance between the wall surface member 21 and the reinforcing fiber sheet 2 to 28 mm and the distance between the reinforcing fiber sheets 21 to 84 mm (Lb/Ln=3). Observation of the state of the application part revealed that the liquid level in the area sandwiched between the wall surface member and the reinforcing fiber sheet was lowered, resulting in a liquid level difference of about 10 mm between the front and back of the reinforcing fiber sheet. No cracking of the fiber bundle was observed. Furthermore, when the liquid pool 22 was observed, fluff was observed near the liquid surface at the upper end (running stability "Good"). The impregnation degree of the matrix resin of the obtained prepreg was 85%.

[Example 8]
A prepreg was produced using the pressing guide 14 and the application portion 20f shown in FIG. 18 according to the present invention. The position of the pressing guide 14 was further adjusted from Example 7 to set the interval between the wall surface member 21 and the reinforcing fiber sheet 2 to 35 mm and the interval between the reinforcing fiber sheets 21 to 70 mm (Lb/Ln=2). Observation of the state of the application part revealed that the liquid level in the area sandwiched between the wall member and the reinforcing fiber sheet was lowered, and a liquid level difference of about 5 mm was generated between the front and back of the reinforcing fiber sheet. No cracking of the fiber bundle was observed. Also, no fluff was observed in the liquid pool 22 (running stability "Very Good"). The impregnation degree of the matrix resin of the obtained prepreg was 85%.

Table 3 is a table summarizing experimental results in which CFRP prepregs were produced in Examples 9 to 12, and the running stability of the reinforcing fiber sheets and the quality of the obtained prepreg end portions were evaluated. As the implementation conditions common to Examples 9 to 12, two reinforcing fiber sheets were introduced into the liquid pool portion 22 with an interval in the thickness direction thereof, and the interval between the wall surface member 21 and the reinforcing fiber sheet 2 was 35 mm. The interval between the reinforcing fiber sheets 21 was set to 70 mm (Lb/Ln=2). Further, in Examples 9 to 12, the width regulating mechanism 27 (plate-shaped bush) as shown in FIG. The width regulating mechanism 27 has a V-shape as shown in FIG. 9(d), and the dimensions Lx, Ly, and E of each portion in FIG. 18 are different for each embodiment. 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 plate-like bush.

[Example 9]
A prepreg was produced using the coating portion 20f of FIG. 18 and the width regulating mechanism 27 of FIG. 17, the distance Lx=Ly=5 mm between the wall surface member or the side plate member and the width regulating mechanism 27, and the dimension E of the width regulating mechanism in the thickness direction of the reinforcing fiber sheet was 5 mm. Observation of the state of the application part revealed that the liquid level in the area sandwiched between the wall member and the reinforcing fiber sheet was lowered, and a liquid level difference of about 5 mm was generated between the front and back of the reinforcing fiber sheet. No cracking of the fiber bundle was observed. Also, no fluff was observed in the liquid pool 22 (running stability "Very Good"). Further, when the obtained prepreg was sampled and observed, it was found that the fiber bundle was continuously broken and cracked at the widthwise end of the prepreg (end quality "Fair").

[Example 10]
A prepreg was produced using the coating portion 20f of FIG. 18 and the width regulating mechanism 27 of FIG. The shape of the width regulating mechanism 27 is changed from that of the ninth embodiment, and will be described with reference to FIG. The dimension in the direction was set to E=5 mm. Observation of the state of the applied portion revealed that the liquid level difference between the front and back of the reinforcing fiber sheet was less than 5 mm, and no cracking of the fiber bundles was observed in the reinforcing fiber sheet. Also, no fluff was observed in the liquid pool 22 (running stability "Excellent"). Further, when the obtained prepreg was sampled and observed, it was found that the fiber bundle was continuously broken and cracked at the widthwise end of the prepreg (end quality "Fair").

[Example 11]
A prepreg was produced using the coating portion 20f of FIG. 18 and the width regulating mechanism 27 of FIG. The shape of the width regulating mechanism 27 is further changed from that of the fifth embodiment, and will be described with reference to FIG. The dimension in the thickness direction was E=10 mm. Observation of the state of the applied portion revealed that the liquid level difference between the front and back of the reinforcing fiber sheet was less than 5 mm, and no cracking of the fiber bundles was observed in the reinforcing fiber sheet. Also, no fluff was observed in the liquid pool 22 (running stability "Excellent"). In addition, when the obtained prepreg was collected and observed, although no breakage or cracking of the fiber bundle was observed at the widthwise end of the prepreg, unevenness in the thickness of the reinforcing fiber was observed (quality of the end "Good"). .

[Example 12]
A prepreg was produced using the coating portion 20f of FIG. 18 and the width regulating mechanism 27 of FIG. The shape of the width regulating mechanism 27 is further changed from that of the eleventh embodiment, and will be described with reference to FIG. The dimension in the thickness direction was E=20 mm. Observation of the state of the applied portion revealed that the liquid level difference between the front and back of the reinforcing fiber sheet was less than 5 mm, and no cracking of the fiber bundles was observed in the reinforcing fiber sheet. Also, no fluff was observed in the liquid pool 22 (running stability "Excellent"). Further, when the obtained prepreg was sampled and observed, no breakage or cracking of the fiber bundle was observed at the ends of the prepreg in the width direction, and the thickness of the reinforcing fibers was uniform (the quality of the ends was "Good").

The multilayer structure prepreg of the present invention has both the vacuum pressure formability of FRP represented by CFRP and the handleability as a prepreg, and is used for aerospace applications, automobiles, trains, ships, etc. Structural materials and interior materials, pressure vessels, It can be widely applied to industrial material applications, sports material applications, medical equipment applications, housing applications, civil engineering and construction applications, and the like.

1 Reinforcing fiber 2 Reinforcing fiber sheet 3 Multilayer structure prepreg/prepreg 4 Matrix resin 5a, 5b Release sheet 11 Creel 12 Aligning device 13 Conveying roll 14 Pressing guide 15 Take-up rolls 16a, 16b Release sheet supply device 17 Winding device 18 Liquid Middle guide 20 Application portion 20a Another embodiment of application portion 20b Another embodiment of application portion 20c Another embodiment of application portion 20d Another embodiment of application portion 20e Another embodiment of application portion 20f Another embodiment Application portions 21a and 21b Wall surface members 21c and 21d Different shaped wall surface members 21e and 21f Different shaped wall surface members 21g and 21h Different shaped wall surface members 21i and 21j Different shaped wall surface members 22 Liquid reservoir 22a Liquid A region 22b in which the cross-sectional area of the pooling portion continuously decreases A region 22c in which the cross-sectional area of the liquid pooling portion does not decrease A region 23 of the liquid pooling portion in which the cross-sectional area decreases intermittently Narrowed portions 24a and 24b Side plate member 25 Outlet 26 gaps 27, 27a, 27b width regulating mechanism 30 application parts 31a, 31b in an embodiment different from the present invention wall surface member 32 of application part 30 liquid pool 33 of application part 30 cross-sectional area of liquid pool of application part 30 intermittently decreasing regions 35a, 35b, 35c Bar 100 Coating device B Depth C of liquid reservoir 22 Height D to upper liquid surface of liquid reservoir 22 Gap E of constricted section Reinforcing fiber of width regulating mechanism 27 Dimension in the sheet thickness direction F Horizontal flow G Width regulation position H Vertical height J at which the cross-sectional area of the liquid reservoir 22 continuously decreases Upper edge line L of the position along the tapered shape of the width regulation mechanism 27 Width L2 of the liquid pool portion 22 Width regulated by the width regulating mechanism at the lower end of the width regulating mechanism Ln The narrowest interval Lb at the upper end liquid surface The widest interval Lx at the upper end liquid surface Interval Ly between the width regulating mechanism of the wall surface member and the width of the side plate member Intervals R, Ra, and Rb between regulating mechanisms Eddy flow T Circulating flow T′ Circulating flow W Width Y of prepreg 1b measured immediately below constricted portion 23 Width Z of constricted portion 23 Traveling direction (vertical direction) of sheet-shaped reinforcing fiber bundle 1a downward)
α Angle between the Z direction (vertical line) and the running direction of the reinforcing fiber sheet θ Opening angle of the tapered portion 411 Creel 412 Reinforcing fiber bobbin 413 Direction changing guide 414 Reinforcing fiber 415 Reinforcing fiber arrangement device 416 Reinforcing fiber sheet 417 Widening device 418 Smooth Heating device 419 Direction changing roll 420 Preheating device 421 Pressing guide 430 Coating unit 441 Direction changing roll 442 Release sheet (upper) supply device 443 Release sheet (lower) supply device 445 Direction change roll 446 Release sheet 447 Lamination roll 449 Height Tension take-up S-shaped roll 450 Additional impregnation device 451 Hot plate 452 Heating nip roll 453 Simple additional impregnation device 461 Cooling device 462 Take-up device 463 Release sheet (upper) winding device 464 Winder 471 Prepreg 472 Prepreg/release sheet

Claims (13)

A multilayer structure prepreg in which impregnated layers in which a matrix resin is impregnated in a reinforcing fiber sheet and non-impregnated layers are alternately laminated, wherein the upper and lower surfaces of the multilayer structure prepreg are composed of impregnated layers, and the upper and lower surfaces are excluded. At least one impregnated layer in the inner layer portion of the multilayer structure prepreg, the maximum value of the unimpregnated portion ratio in the unimpregnated layer is 60% or less, and either or both of the upper surface and the lower surface of the multilayer structure prepreg A multi-layered prepreg with a release sheet attached to the surface. 2. The multi-layer prepreg with a release sheet according to claim 1, wherein the arrangement of the reinforcing fibers in the plane direction is substantially the same in the multi-layer prepreg. A prepreg roll obtained by winding the multi-layered prepreg with a release sheet according to claim 1 or 2. A prepreg tape having a width of 30 mm or less, comprising the multi-layered prepreg with a release sheet according to claim 1 or 2. A step of obtaining the multilayer structure prepreg with a release sheet according to claim 1 or 2, the prepreg roll according to claim 3, or the prepreg tape according to claim 4, and the multilayer structure prepreg with the release sheet, the prepreg roll, or A method of manufacturing a composite material, comprising the step of molding a prepreg tape. A liquid pool portion in which matrix resin as a coating liquid is stored and which has a portion in which the cross-sectional area continuously decreases downward in the vertical direction; A method for manufacturing a prepreg in which a reinforcing fiber sheet is passed vertically downward through a coating portion provided to apply a coating liquid to the reinforcing fiber sheet, wherein a plurality of reinforcing fiber sheets are spaced in the thickness direction in the liquid pool portion. A method of manufacturing a prepreg, comprising the steps of: introducing the prepreg with a gap therebetween; and uniting the plurality of reinforcing fiber sheets inside the application section after the introduction. At the upper end liquid surface of the liquid pool, the narrowest space Ln and the widest space Lb among the space between the wall surface (wall surface member) of the liquid pool and the reinforcing fiber sheet and the space between the plurality of reinforcing fiber sheets. 7. The method for manufacturing a prepreg according to claim 6, wherein the relationship of satisfies 1≦Lb/Ln≦3. 8. The manufacturing of the prepreg according to claim 6 or 7, wherein a width regulating mechanism is installed corresponding to each end in the arrangement direction of each of the plurality of reinforcing fiber sheets in the liquid pool to regulate the width of the reinforcing fiber sheet. Method. 9. The method of manufacturing a prepreg according to claim 8, wherein the width regulating mechanisms are divided from each other at the upper liquid surface of the liquid reservoir. 10. The method of manufacturing a prepreg according to claim 8, wherein a distance between the width regulating mechanism and the wall surface (wall surface member) of the liquid pool is 10 mm or more at the liquid level at the upper end of the liquid pool. The method of manufacturing a prepreg according to any one of claims 8 to 10, wherein the width regulating mechanism extends from the lower end of the liquid reservoir to the upper liquid surface. The method for manufacturing a prepreg according to any one of claims 8 to 11, wherein the dimension of the width regulating mechanism with respect to the thickness direction of the reinforcing fiber sheet is 10 mm or more at the liquid level at the upper end of the liquid reservoir. A prepreg manufacturing apparatus for applying a matrix resin as a coating liquid to a reinforcing fiber sheet, the liquid reservoir having a portion in which the coating liquid can be stored and whose cross-sectional area continuously decreases downward in the vertical direction; An application section having a narrowed portion having a slit-shaped outlet communicating with the lower end of the liquid pool, and a plurality of reinforcing fiber sheets are run vertically downward at intervals in the thickness direction and introduced into the application section. A prepreg having a running mechanism equipped with an introduction mechanism and a lead-out mechanism for withdrawing the prepreg led out from the constricted portion, and a uniting mechanism for uniting the plurality of reinforcing fiber sheets inside the application unit. manufacturing device.

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