FRP precursor manufacturing method

Abstract

Provided is a method for producing an FRP precursor having a precoating step for applying a resin varnish having a filler content of 5 vol% or less in the solids fraction to a sheet-shaped aggregate and a melt pasting step for melt pasting a pair of resin films, each having a filler content of 30 vol% or higher, to both surfaces of the aggregate after the precoating step.

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing an FRP precursor. [Background technology]

[0002] FRP (Fiber Reinforced Plastics) is a composite material that uses a highly elastic material such as fiber as an aggregate and places this aggregate in a base material (matrix) such as plastic to improve its strength. Taking advantage of its weather resistance, heat resistance, and chemical resistance, FRP is an inexpensive, lightweight, and highly durable composite material. Taking advantage of these properties, FRP is used in a wide range of fields. For example, due to its moldability and high strength, FRP is used as a structural material for housing equipment, ships, vehicles, aircraft, etc. Furthermore, taking advantage of its insulating properties, FRP is also used in the field of electronic parts such as electrical equipment and semiconductor chips.

[0003] The integration density of electronic components such as semiconductor chips is becoming increasingly high, and the printed wiring boards on which they are mounted are also becoming increasingly smaller. Although semiconductor chips generate little heat, they are densely packed together, resulting in extremely high heat density per unit area (see, for example, Non-Patent Document 1). While cooling methods using cooling fans or heat dissipation fins are employed to dissipate the generated heat, the installation of these components poses a problem: the device becomes larger. Wearable electronic devices, in particular, require small, light, and thin designs, making cooling methods using cooling fans or heat dissipation fins difficult to employ. Therefore, the present applicant previously proposed a method for increasing the thermal conductivity of printed wiring boards to dissipate the generated heat throughout the device via the printed wiring board (see Patent Document 1).

[0004] To increase the thermal conductivity of printed wiring boards, a method is often used in which FRP precursors, such as prepregs, are heavily loaded with fillers that have higher thermal conductivity than the resin. However, a high loading of fillers can impregnate aggregates, such as woven glass fabric, with the resin composition, potentially resulting in poor insulation and heat resistance. Furthermore, when the resin composition is applied to the aggregate, the filler may settle in the impregnation container, making it impossible to apply the desired amount of filler-containing resin composition to the aggregate.

[0005] For this reason, a method may be adopted in which the resin varnish to be used is applied to a carrier film, and then dried to form a resin film, and the resin film is then laminated onto the aggregate under heat and pressure conditions (see, for example, Patent Document 2). With this method, settling of the filler is unlikely to occur during lamination, and it becomes possible to laminate a resin film containing a desired amount of filler onto the aggregate. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-031405 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-176169 [Non-patent literature]

[0007] [Non-Patent Document 1] Scientific Systems Research Group, 2006 Scientific and Technical Computing Subcommittee Materials (October 5, 2006), Toshishige Ando, ​​Trends in Semiconductor and Computer Technology Summary of the Invention [Problem to be solved by the invention]

[0008] The method using a resin film, as described in Patent Document 2, etc., uses a material with lower fluidity than the method of applying a resin varnish. Therefore, when laminating the resin film to, for example, glass cloth, care must be taken to ensure that the resin is sufficiently impregnated between the filaments of the yarn that make up the glass cloth. However, during lamination, the yarn can exhibit the function of a filter cloth, with only the resin impregnating between the filaments of the yarn, resulting in the filler agglomerating on the surface of the yarn like a filtration residue. When this occurs, it has been found that the filler ratio of the resin layer near the surface of the glass cloth increases locally, resulting in high viscosity and poor flowability, and poor formability during lamination.

[0009] Therefore, the object of the present disclosure is to provide a method for producing an FRP precursor that uses a resin film, which allows the resin to penetrate into the voids in the aggregate while suppressing local increases in the filler ratio. [Means for solving the problem]

[0010] As a result of intensive research, the present inventors have found that the above object can be achieved by the method for producing an FRP precursor of the present disclosure. The present disclosure includes the following embodiments [1] to [8].

[0011] [1] Pre-coating a resin varnish containing filler material at a solid content of 5% by volume or less on the sheet aggregate; and After the pre-application, a pair of resin films each having a filler content of 30% by volume or more are melt-attached to both surfaces of the aggregate; A method for producing an FRP precursor, comprising: [2] The method for producing an FRP precursor according to the above [1], wherein the amount of resin varnish used in the pre-application satisfies the following formula (1):

number

[0012] According to the manufacturing method of the FRP precursor of this embodiment, even while using a resin film, it is possible to impregnate the resin into the fine details of the aggregate while suppressing a local increase in the filler ratio. Therefore, there is no local increase in the filler ratio of the resin layer near the surface of the glass cloth, and the viscosity and flowability are not increased, so deterioration of formability during lamination can be suppressed. Therefore, formability can be ensured while improving thermal conductivity by the filler. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a conceptual diagram of an apparatus that can be used in the pre-coating operation in the method for producing an FRP precursor according to this embodiment. [Figure 2] FIG. 1 is a conceptual diagram of an apparatus that can be used after pre-coating in the method for producing an FRP precursor according to this embodiment. [Figure 3] FIG. 2 is a schematic diagram of a cross section of a glass cloth for explaining bulk thickness. DETAILED DESCRIPTION OF THE INVENTION

[0014] This embodiment involves pre-coating a resin varnish having a filler content of 5% by volume or less of the solid content onto a sheet-like aggregate (hereinafter, for convenience, this may be referred to as the "pre-coating step"); After the pre-application, a pair of resin films each having a filler content of 30% by volume or more is melt-attached to both surfaces of the aggregate (hereinafter, for convenience, referred to as the "melt-attaching step"); The present invention relates to a method for producing an FRP precursor, comprising: Here, in this specification, for convenience, a specific operation, such as the pre-coating process and the melt-pasting process, may be referred to as an "XX process," but the XX process is not limited to only the embodiments specifically described in this specification.

[0015] Hereinafter, one embodiment of a method for producing an FRP precursor according to this embodiment will be described with reference to FIGS. 1 and 2, but this embodiment is not limited to this embodiment. Specifically, the explanation will be given using a pre-coating device 100 and an FRP precursor manufacturing device 200 (hereinafter sometimes simply referred to as the FRP precursor manufacturing device 200) that is used after the pre-coating step. The FRP precursor manufacturing device 200 will be explained as a device that uses a pair of resin films 54 to attach them to both sides of a sheet-like pre-coated aggregate 41. The pre-coating device 100 and the FRP precursor manufacturing device 200 are under normal pressure. Since this embodiment is carried out under normal pressure, unlike when vacuum lamination is used, it is easy to deal with any manufacturing problems that may occur. The FRP precursor manufacturing method according to this embodiment can be carried out using the pre-coating device 100 and the FRP precursor manufacturing device 200. 1 and 2 show a "two-stage method" in which the pre-coated aggregate 41 is first wound up by the pre-coated aggregate winding device 8 in the pre-coating device 100 and then used in the FRP precursor manufacturing apparatus 200 used after the pre-coating process. However, a "one-stage method" may also be employed in which the pre-coated aggregate 41 is not wound up by the pre-coated aggregate winding device 8 in the pre-coating device 100 shown in FIG. 1 but is instead used directly in the FRP precursor manufacturing apparatus 200 used after the pre-coating process. However, the pre-coating device 100 shown in FIG. 1 can increase the coating speed, and the aggregate delivery rate can be increased compared to the FRP precursor manufacturing apparatus 200 shown in FIG. 2. For this reason, it is preferable that the pre-coating device 100 and the FRP precursor manufacturing apparatus 200 are independent of each other, i.e., the two-stage method is preferred. In the two-stage method, using multiple FRP precursor manufacturing apparatuses 200 significantly increases productivity.

[0016] (Pre-coating step, pre-coating device 100; Figure 1) As described above, the pre-application step is a step of applying a resin varnish having a filler content of 5% by volume or less of the solid content to the sheet-like aggregate 40. Here, the term "solid content" as used herein refers to components in the composition other than water and volatile substances such as organic solvents, which will be described later. In other words, the term "solid content" includes liquid, starch syrup-like, and wax-like substances at room temperature around 25°C, and does not necessarily mean a solid. The pre-coating step can be performed using a pre-coating device 100. The pre-coating device 100 includes a resin varnish 13a, a container 13b, and deflecting rollers 14, 15, and 16. The pre-coating device 100 applies the resin varnish 13a to the aggregates 40 by submerging the aggregates 40 delivered from the aggregate delivery device 2 in the resin varnish 13a. The pre-coating device 100 delivers the aggregates 41 to which the resin varnish 13a has been applied (i.e., the pre-coated aggregates) toward a dryer 17. The resin varnish 13a is a resin varnish in which the content of filler is 5% by volume or less of the solid content, and will be described in detail later. There are no particular limitations on the container 13b as long as it can store the resin varnish 13a and has a width greater than the width of the aggregate 40. A predetermined amount of resin varnish 13a is placed in the container 13b. The diverting rollers 14, 15, and 16 are all rollers that diverge the direction in which the aggregates 40 move. The diverting rollers 14 and 16 are located at the front and rear of the upper side of the container 13b in the direction in which the aggregates 40 are sent out, respectively, so that the aggregates 40 are diverted above them. The lower side of the diverting roller 15 is located below the surface of the resin varnish 13a in the container 13b, so that the aggregates 40 are diverted below it. In FIG. 1, the diverting roller 15 is submerged in the resin varnish 13a.

[0017] In the manufacturing method of the FRP precursor of this embodiment, resin varnish 13a is applied to the aggregate 40 in advance, thereby introducing resin into the voids of the aggregate. Here, the voids of the aggregate refer to the spaces between the yarn filaments that make up the glass cloth, for example, if the aggregate is glass cloth. Therefore, when laminating a thermosetting resin sheet to the aggregate in the melt-bonding process described below, the resin in the thermosetting resin sheet is prevented from penetrating between the yarn filaments, preventing the filler from aggregating on the yarn surface like a filtration residue. As a result, there is no local increase in the filler ratio in the resin layer near the glass cloth surface, and the viscosity and flowability are not increased, preventing deterioration of formability during lamination. Therefore, formability can be ensured while improving thermal conductivity through the filler. Furthermore, the pre-coating device 100 tends to improve adhesion between the resin film and the aggregate. Hereinafter, these effects may be referred to as "Effect A." Note that Effect A tends to be particularly pronounced when the bulk thickness of the aggregate is 30 μm or more. The greater the bulk thickness of the aggregate, the greater the amount of resin from the thermosetting resin sheet that penetrates into the aggregate, making it easier for the filler in the thermosetting resin sheet to aggregate on the surface of the yarn. Therefore, when the bulk thickness of the aggregate is 30 μm or more, Effect A obtained by pre-impregnating the aggregate with resin varnish becomes significant. From this perspective, the bulk thickness of the aggregate is preferably 30 μm or more, more preferably 30 to 250 μm, even more preferably 35 to 200 μm, and particularly preferably 40 to 180 μm. The bulk thickness of the aggregate may be 30 to 70 μm, 100 to 250 μm, or 140 to 250 μm. The "bulk thickness" refers to the thickness of the part shown in Figure 3, and more specifically, it refers to the thickness measured in accordance with JIS R3420 (2013) 7.10.1 (however, in "7.10.1.4 Operation", Method B is adopted).

[0018] Here, in the pre-coating step, the amount of resin varnish used preferably satisfies the following formula (1).

number

[0019] Hereinafter, the "volume of solid content of applied resin varnish / (bulk volume of aggregate-true volume of aggregate)" in formula (1) may be referred to as "solid content impregnation rate." The lower limit of the solid content impregnation rate is preferably 0.10, more preferably 0.15, and the upper limit is preferably 0.5, more preferably 0.45. These numerical values ​​can be rewritten independently as the lower limit or upper limit in formula (1). With regard to the amount of resin varnish used, when the solid content impregnation rate is 0.05 or more, the above-mentioned effect of preliminarily applying the resin varnish 13a to the aggregate 40 tends to be fully realized. Furthermore, when the solid content impregnation rate is 0.6 or less, the filler in the resin film can be sufficiently impregnated into the gaps between the yarns of the glass cloth, which makes it easier to produce an FRP precursor highly filled with filler and also makes it possible to avoid excessive impregnation of the resin in the resin varnish, which tends to make it easier to maintain the properties of the resin film.

[0020] After resin varnish 13a is applied to aggregate 40 in advance, the resin varnish is heated and dried in dryer 17 to remove the organic solvent in the resin varnish and adjust the hardness of the resin applied to the aggregate. The dryer is not particularly limited, but a hot air dryer is preferred. The drying temperature is not particularly limited, but is preferably adjusted in the range of 120 to 200°C, and may be 150 to 190°C or 160 to 185°C. The pre-coated aggregate 41, the hardness of which has been adjusted by the dryer 17, moves towards the pre-coated aggregate winding device 8.

[0021] (Apparatus 200 for manufacturing FRP precursors that can be used after the pre-coating process; Figure 2) The FRP precursor manufacturing apparatus 200 includes a pre-coated aggregate delivery device 2', a pair of resin film delivery devices 3, 3, a sheet heating and pressurizing device 6, and an FRP precursor winding device 9. The FRP precursor manufacturing apparatus 200 preferably further includes a sheet pressurizing and cooling device 7, a pair of protective film peeling mechanisms 4, 4, and a pair of protective film winding devices 5, 5.

[0022] The pre-coated aggregate delivery device 2' is a device that delivers the pre-coated aggregate 41 obtained in the pre-coating step, and is a device that delivers the pre-coated aggregate 41 wound around the roll by rotating the roll in the direction opposite to the winding direction. In Figure 2, the pre-coated aggregate delivery device 2' delivers the pre-coated aggregate 41 from below the roller toward the FRP precursor winding device 9.

[0023] Each resin film feeding device 3 has a roll on which the resin film 50 fitted with a protective film is wound, and a support mechanism that rotatably supports the roll while applying a predetermined tension to the resin film 50 fitted with a protective film to be fed out. Each resin film feeding device 3 is a device that rotates a roll around which the protective film-attached resin film 50 is wound in a direction opposite to the winding direction, and feeds out the rolled resin film 50. As will be described later, the protective film-attached resin film 50 is a sheet-like film that includes a resin film 54, a protective film 52 laminated on one aggregate-side film surface 54a of the resin film 54 (the surface of the resin film 54 that faces the aggregate 40), and a carrier film (not shown) laminated on the side of the resin film 54 opposite to the protective film 52.

[0024] The pair of resin film delivery devices 3 and 3 are located on the front surface 41a side and the back surface 41b side of the delivered pre-coated aggregate 41, respectively. One of the resin film delivery devices 3 is positioned on the surface 41a side of the delivered pre-coated aggregate 41, and is a device that delivers one of the protective film-coated resin films 50 from the underside of the roller toward one of the protective film peeling mechanisms 4 so that the protective film 52 is positioned on the side of the delivered pre-coated aggregate 41. Similarly, the other resin film feeding device 3 is positioned on the back surface 41b side of the fed pre-coated aggregate 41, and is a device that feeds the other protective film-coated resin film 50 from the upper side of the roller toward the other protective film peeling mechanism 4 so that the protective film 52 is positioned on the fed aggregate 41 side.

[0025] The pair of protective film peeling mechanisms 4 and 4 are deflecting rollers located on the front surface 41a side and the back surface 41b side of the fed pre-coated aggregate 41, respectively. One protective film peeling mechanism 4 receives the protective film-attached resin film 50, which is sent out from one resin film delivery device 3 and advances toward one protective film peeling mechanism 4, on the surface of a rotating deflecting roller, and advances one resin film 54 of one protective film-attached resin film 50 toward the sheet heating and pressurizing device 6, while advancing one protective film 52 toward one protective film winding device 5, thereby peeling one protective film 52 from one protective film-attached resin film 50. This exposes the aggregate-side film surface 54a of one resin film 54. Similarly, the other protective film peeling mechanism 4 receives the other protective film-attached resin film 50, which is fed from the other resin film feed device 3 and advances toward the other protective film peeling mechanism 4, on the surface of a rotating deflecting roller, and advances the other resin film 54 of the other protective film-attached resin film 50 toward the sheet heating and pressurizing device 6, while advancing the other protective film 52 toward the other protective film take-up device 5, thereby peeling the other protective film 52 from the other protective film-attached resin film 50. This exposes the aggregate-side film surface 54a of the other resin film 54.

[0026] Before the film pressure-welding step described later, it is preferable to preheat the aggregate-side film surface 54a of both surfaces of the resin film 54 by preheating mechanisms 11a and 11b (hereinafter referred to as "film preheating step A"). This promotes melting of the thermosetting resin of each resin film 54, making it easier to melt and bond the films. From a similar viewpoint, it is preferable to further preheat both surfaces (the front surface 41a side and the back surface 41b side) of the pre-coated aggregate 41 using preheating mechanisms 10a and 10b (hereinafter referred to as "aggregate preheating process B") before the film pressing process described later. This embodiment preferably includes at least one of the film preheating step A and the aggregate preheating step B, and more preferably includes both, but it is not necessary to include one or both of them.

[0027] The heating temperatures in the film preheating step A and the aggregate preheating step B are both preferably 5 to 70° C. higher, more preferably 7 to 60° C. higher, and more preferably 10 to 50° C. higher than the heating temperature in the film pressure welding step described below. These heating temperatures are the heating temperatures in preheating mechanisms 10a, 10b, 11a, and 11b, and refer to the surface temperatures of the resin film and the aggregate, respectively. In the film preheating step A, the heating temperature is more preferably set so that the surface temperature of the resin film is in the range of minus 20°C to plus 30°C of the minimum melt viscosity temperature of the resin film, even more preferably set so that it is in the range of minus 10°C to plus 25°C of the minimum melt viscosity temperature of the resin film, particularly preferably set so that it is in the range of minus 5°C to plus 15°C of the minimum melt viscosity temperature of the resin film, and most preferably set so that it is in the range of plus 2°C to plus 15°C of the minimum melt viscosity temperature of the resin film. Herein, the minimum melt viscosity temperature is a temperature measured with a rheometer, and more specifically, a temperature measured according to the method described in the Examples. Furthermore, in the aggregate preheating step B, the heating temperature is more preferably set so that the surface temperature of the resin impregnated in the aggregate is in the range of minus 20°C to plus 30°C of the minimum melt viscosity temperature of the resin, even more preferably set so that it is in the range of minus 5°C to plus 30°C of the minimum melt viscosity temperature of the resin, particularly preferably set so that it is in the range of plus 5°C to plus 25°C of the minimum melt viscosity temperature of the resin, and most preferably set so that it is in the range of plus 8°C to plus 17°C of the minimum melt viscosity temperature of the resin. If the heating temperatures in the film preheating step A and the aggregate preheating step B are too low, the degree of softening of the resin film and the resin in the aggregate tends to be small, and the mixing of the resin film and the aggregate tends to be poor. If the preheating temperature is too high, heat curing proceeds too quickly, hardening the resin film and the resin in the aggregate, and again, the mixing of the resin film and the aggregate tends to be poor. The heating method in the film preheating step A and the aggregate preheating step B is not particularly limited, and various methods such as radiation, contact, and convection can be used. Among these, radiation is preferred. As a radiation-type heater, infrared light or visible light containing infrared light can be used. By using such a heater, deformation of the resin surface due to "fluttering" of the film and stickiness of the film surface can be suppressed. In the film preheating step A and the aggregate preheating step B, the heating position is preferably within 20 seconds of the line speed, more preferably within 5 seconds of the line speed, before the heating and pressure roll, from the viewpoint of suppressing cooling.

[0028] A pair of protective film winding devices 5 and 5 are located on the front surface 41a side and the back surface 41b side of the delivered pre-coated aggregate 41, respectively, and are winding devices that wind up the protective films 52 and 52 peeled off by a pair of protective film peeling mechanisms 4 and 4.

[0029] (Fusing and pasting process; Figure 2) As described above, the melt-bonding step is a step of melt-bonding a pair of resin films each containing 30% or more by volume of filler onto both surfaces of the aggregate after the pre-application step. The melt-sticking process can be carried out using a sheet heating and pressurizing device 6. The sheet heating and pressurizing device 6 has a pair of heating and compression rollers and a compression force applying mechanism (not shown) that applies a compression force to the pair of heating and compression rollers. The pair of heating and compression rollers have a heater inside so that they can be heated to a predetermined set temperature. The sheet heating and pressurizing device 6 presses the resin films 54, 54 against the inserted pre-coated aggregate 41 with a pair of rotating heating and compression rollers to form a sheet-like FRP precursor 60 (film pressing process), and then sends the FRP precursor 60 toward the sheet pressing and cooling device 7.

[0030] More specifically, the film pressing process is a film pressing process in which, under normal pressure, one of the two surfaces of one of the pair of resin films, the surface facing the aggregate, is pressed against one of the two surfaces of the aggregate, and the other of the two surfaces of the other of the pair of resin films, the surface facing the aggregate, is pressed against the other of the two surfaces of the aggregate, to obtain an FRP precursor. Specifically, resin films 54 and 54 delivered from a pair of protective film peeling mechanisms 4 and 4 are laminated on the front surface 41a and back surface 41b of the pre-coated aggregate 41 delivered from the pre-coated aggregate delivery device 2', respectively, and the pre-coated aggregate 41 and the resin films 54 and 54 delivered from the pair of protective film peeling mechanisms 4 and 4, respectively, are inserted between a pair of heated compression rollers. When the resin film 54 is bonded to the pre-coated aggregate 41 under heat and pressure, the temperature of the heat compression roller is preferably in the range of minus 40°C to plus 20°C of the minimum melt viscosity temperature of the resin film 54, more preferably in the range of minus 30°C to plus 10°C of the minimum melt viscosity temperature of the resin film 54, even more preferably in the range of minus 20°C to minus 5°C of the minimum melt viscosity temperature of the resin film 54, and most preferably in the range of minus 20°C to minus 5°C of the minimum melt viscosity temperature of the resin film 54. Any linear pressure may be used, but a linear pressure that results in oozing of 50 to 1,200 μm from a 6.4 mm punch hole when heat and pressure are applied by roll lamination according to the test method of IPC-TM-650 No. 2.3.17.1B is preferred, and a linear pressure that results in oozing of 100 to 1,000 μm from a 6.4 mm punch hole is more preferred. At this time, one resin film 54 is laminated onto the pre-coated aggregate 41 with the aggregate-side film surface 54a of one resin film 54 in contact with the surface 41a of the pre-coated aggregate 41. Also, the other resin film 54 is laminated onto the pre-coated aggregate 41 with the aggregate-side film surface 54a of the other resin film 54 in contact with the back surface 41b of the pre-coated aggregate 41. In this way, the FRP precursor 60 is formed. The FRP precursor 60 is in a high temperature state when it is delivered from the sheet heating and pressurizing device 6.

[0031] The sheet pressurizing and cooling device 7 has a pair of cooling and compressing rollers and a compressing force applying mechanism (not shown) that applies a compressive force to the pair of cooling and compressing rollers. The pair of cooling and compressing rollers compress and cool the high-temperature FRP precursor 60 sent out from the sheet heating and pressurizing device 6 with the pair of rotating cooling and compressing rollers, and send it to the FRP precursor winding device 9.

[0032] The FRP precursor winding device 9 has a roll that winds up the sheet-like FRP precursor 60 sent out from the sheet pressurizing and cooling device 7, and a drive mechanism (not shown) that rotates the roll.

[0033] Next, the aggregate, the resin varnish, and the resin film used in the method for producing an FRP precursor will be described in detail.

[0034] (aggregate) Examples of the aggregate include inorganic fiber substrates such as glass and carbon; organic fiber substrates such as aramid and cellulose; and metal fiber substrates made of iron, copper, aluminum, alloys of these metals, etc., used alone or in combination of two or more types, such as woven fabrics and nonwoven fabrics. The aggregate may be appropriately selected depending on the purpose, such as insulation and conductivity. Glass cloth (glass woven fabric) can be selected as the aggregate. The aggregate is 1m 2 The gap between the aggregates is 15cm 3 When the voids are large, the effect A tends to be significant. This is because, when there are many voids, the resin in the resin film easily penetrates into the voids, while the filler has difficulty penetrating into the voids, and when there are few voids, the amount of resin in the resin film that penetrates into the voids is small, so the filler does not aggregate to a large extent like a filtration residue on the aggregate surface (the yarn surface in the case of glass cloth). 1m 2 From the above viewpoint, the voids of the aggregate per unit area should be 15 to 100 cm 3 May be 20~85cm 3 May be 23~75cm 3The void volume can be calculated by subtracting the true volume from the bulk volume. Furthermore, when the aggregate is a woven fabric such as glass cloth, if the number of filaments constituting the yarn is 50 or more, the woven fabric tends to function easily as a filter cloth for the resin film, and in the case of such aggregate, the effect A is likely to be significantly exhibited. The number of filaments constituting the yarn may be 50 to 500, 50 to 450, 100 to 450, or 100 to 300. Alternatively, the number of filaments constituting the yarn may be 300 to 500.

[0035] (resin varnish) As described above, the resin varnish used in the pre-coating step is a resin varnish with a filler content of 5% by volume or less based on the solid content, and the remaining solid content is volatile components such as organic solvents. The filler content in the resin varnish is preferably 3% by volume or less, more preferably 2.5% by volume or less, and even more preferably 2.0% by volume or less based on the solid content. Such a small amount of filler in the resin varnish is used to prevent the resin varnish from becoming too fluid. For example, when a resin with a higher viscosity is used, the resin varnish does not need to contain a filler. In other words, the lower limit of the filler content in the resin varnish used in the pre-coating step may be 0% by volume based on the solid content, or may be 0.2% by volume based on the solid content, 0.5% by volume based on the solid content, 1.0% by volume based on the solid content, or 1.3% by volume based on the solid content. The average particle size of the filler contained in the resin varnish is preferably 0.1 to 10 μm, more preferably 0.3 to 7 μm, and even more preferably 0.5 to 5 μm. If the average particle size of the filler contained in the resin varnish is within the above range, the fluidity of the resin varnish tends to be appropriate.

[0036] The filler that can be contained in the resin varnish is not particularly limited, and examples thereof include oxides such as silica, aluminum oxide, zirconia, mullite, magnesia, etc.; hydroxides such as aluminum hydroxide, magnesium hydroxide, hydrotalcite, etc.; nitride ceramics such as aluminum nitride, silicon nitride, boron nitride, etc.; sparingly soluble salts such as titanates such as barium titanate, calcium titanate, etc.; natural or synthetic clay minerals such as talc, montmorillonite, saponite, hydrotalcite, etc.; metal particles, carbon particles, etc. As the filler that can be contained in the resin varnish, inorganic fillers are preferred from the viewpoints of insulation and fluidity adjustment, oxides and hydroxides are more preferred, and silica and aluminum hydroxide are even more preferred from the viewpoints of price, insulation, low thermal expansion, flame retardancy, mechanical wear resistance, etc.

[0037] The solid content concentration of the resin varnish is preferably 5 to 55 mass %, from the viewpoint of allowing the resin to penetrate into the voids in the aggregate (for example, between the filaments of the yarn in the case of glass cloth), and may be 5 to 50 mass %, 5 to 45 mass %, 15 to 45 mass %, 25 to 45 mass %, or 35 to 45 mass %. The organic solvent contained in the resin varnish is not particularly limited and includes, for example, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, 4-methyl-2-pentanone, etc.; aromatic solvents such as toluene, xylene, mesitylene, etc.; ester solvents such as ethyl acetate, γ-butyrolactone, etc.; ether solvents such as tetrahydrofuran, etc.; alcohol solvents such as ethylene glycol monoethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, etc.; nitrogen atom-containing solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, etc.; sulfur atom-containing solvents such as dimethyl sulfoxide, etc. These organic solvents may be used alone or in combination of two or more. The other components contained in the resin varnish are explained in the same manner as the components contained in the resin film described below.

[0038] (resin film) The resin film is not particularly limited, but is preferably a thermosetting resin film. In this specification, the description of the resin film can be read as a description of the thermosetting resin film. The resin film used for melt-bonding to aggregate is a resin composition (preferably a thermosetting resin composition) containing 30% or more by volume of filler, which is formed into a film and then dried. In particular, in the case of a thermosetting resin composition, the film is formed into a film and then dried to B-stage. Here, B-staging refers to bringing the composition into a B-stage state as defined in JIS K6900 (1994), also known as semi-curing. There are no particular limitations on the drying conditions, but heat drying at 80 to 180°C for 1 to 5 minutes can be used. The thermosetting resin film contains a thermosetting resin, a filler, and other components as required. Each component that the thermosetting resin film may contain will be described in detail below.

[0039] The thermosetting resin is not particularly limited, and examples thereof include phenol resin, urea resin, furan resin, epoxy resin, polyimide resin, etc. In particular, epoxy resin is preferred from the viewpoints of workability, handling, and cost.

[0040] The epoxy resin is preferably a bifunctional or higher functional epoxy resin. The bifunctional or higher functional epoxy resin is not particularly limited, and examples thereof include bisphenol-type epoxy resins such as bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, and bisphenol AD-type epoxy resins; alicyclic epoxy resins; novolac-type epoxy resins such as phenol novolac-type epoxy resins, cresol novolac-type epoxy resins, bisphenol A novolac-type epoxy resins, and aralkyl novolac-type epoxy resins; diglycidyl ethers of polyfunctional phenols; and hydrogenated versions thereof. These epoxy resins may be used alone or in combination of two or more. Although not particularly limited, the epoxy resin preferably contains at least one selected from the group consisting of bisphenol-type epoxy resins and novolac-type epoxy resins, and more preferably contains a novolac-type epoxy resin. If flame retardancy is required for the FRP precursor, a halogenated epoxy resin may be blended in. Alternatively, to achieve flame retardancy without adding a halogenated epoxy resin, compounds generally referred to as flame retardants or flame retardant assistants, such as tetrabromobisphenol A, decabromodiphenyl ether, antimony oxide, tetraphenylphosphine, organic phosphorus compounds, and zinc oxide, may be added.

[0041] When an epoxy resin is used as the thermosetting resin, an epoxy resin curing agent may be used. The epoxy resin curing agent is not particularly limited, and examples thereof include phenol resins, amine compounds, acid anhydrides, boron trifluoride monoethylamine, isocyanates, dicyandiamide, and urea resins. The phenolic resin is not particularly limited, and examples thereof include resol-type phenolic resins, novolac-type phenolic resins such as phenol novolac resins and cresol novolac resins, naphthalene-type phenolic resins, high-ortho novolac phenolic resins, terpene-modified phenolic resins, terpene phenol-modified phenolic resins, aralkyl-type phenolic resins, dicyclopentadiene-type phenolic resins, salicylaldehyde-type phenolic resins, and benzaldehyde-type phenolic resins. Among these, phenol novolac resins, cresol novolac resins, and partially modified aminotriazine novolac resins are preferred. The amine compound is not particularly limited, and examples thereof include aliphatic amines such as triethylenetetramine, tetraethylenepentamine, and diethylaminopropylamine; and aromatic amines such as metaphenylenediamine and 4,4'-diaminodiphenylmethane. The acid anhydride is not particularly limited, and examples thereof include phthalic anhydride, methyltetrahydrophthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, etc. These epoxy resin curing agents may be used alone or in combination of two or more. The content of the epoxy resin curing agent is preferably an amount such that the reactive group equivalent ratio of the curing agent is 0.3 to 1.5 equivalents per epoxy equivalent of the epoxy resin of 1. When the content of the epoxy resin curing agent is within the above range, it is easy to control the degree of curing, and productivity tends to be good.

[0042] The thermosetting resin film may further contain a curing accelerator. The curing accelerator is not particularly limited, and examples thereof include imidazole compounds, organic phosphorus compounds, tertiary amines, and quaternary ammonium salts. The imidazole compound may be an imidazole compound in which the secondary amino group of imidazole is masked with acrylonitrile, isocyanate, melamine, acrylate, or the like to impart latency. Examples of the imidazole compound used here include imidazole, 2-methylimidazole, 4-ethyl-2-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 1-benzyl-2-methylimidazole, 2-heptadecylimidazole, 4,5-diphenylimidazole, 2-methylimidazoline, 2-ethyl-4-methylimidazoline, 2-undecylimidazol- ine, and 2-phenyl-4-methylimidazoline. Although not particularly limited, the curing accelerator preferably contains an imidazole compound. The thermosetting resin film may also contain a photoinitiator, which has the function of initiating curing by generating radicals, anions, or cations through photodecomposition. These curing accelerators may be used alone or in combination of two or more.

[0043] The content of the curing accelerator is preferably 0.01 to 20 parts by mass relative to 100 parts by mass of the thermosetting resin. When the content of the curing accelerator is 0.01 part by mass or more relative to 100 parts by mass of the thermosetting resin, a sufficient curing acceleration effect tends to be obtained, and when the content is 20 parts by mass or less, the storage stability of the thermosetting resin film and the physical properties of the cured product tend to be excellent, and also economical.

[0044] The thermosetting resin film contains a predetermined amount of filler from the viewpoints of optical opacity, abrasion resistance, low thermal expansion, dielectric properties, thermal conductivity, reducing magnetic permeability, and increasing the amount of contained components. The filler is not particularly limited, but examples thereof include oxides such as silica, aluminum oxide, zirconia, mullite, and magnesia; hydroxides such as aluminum hydroxide, magnesium hydroxide, and hydrotalcite; nitride ceramics such as aluminum nitride, silicon nitride, and boron nitride; sparingly soluble salts such as barium titanate and calcium titanate; natural or synthetic clay minerals such as talc, montmorillonite, saponite, and hydrotalcite; metal particles, carbon particles; and magnetic materials such as ferrite. As the filler contained in the thermosetting resin film, inorganic fillers are preferred from the viewpoint of insulation, and silica is more preferred from the viewpoints of cost and low thermal expansion. The fillers may be used alone or in combination of two or more.

[0045] Fillers vary widely in specific gravity compared to resins, from low to high, so it is preferable to consider the amount of filler added in terms of volume percentage rather than parts by mass. From the viewpoint of highly filling a filler with a high thermal conductivity, the filler content in the thermosetting resin film is 30% by volume or more, preferably 30 to 65% by volume, more preferably 30 to 55% by volume, and even more preferably 35 to 45% by volume. When the filler content in the thermosetting resin film is 30% by volume or more, the filler is highly filled, which can sufficiently increase the thermal conductivity and low thermal expansion of the FRP precursor. Furthermore, when the filler content in the thermosetting resin film is 65% by volume or less, a significant increase in resin viscosity can be suppressed, which tends to prevent deterioration in workability and adhesiveness when melt-applied to aggregate.

[0046] In addition to the above components, other components may be contained as needed within a range that does not impair the effects of this embodiment. For example, a coupling agent may be contained to improve the dispersibility of the filler and the adhesion to the aggregate or the target object. The coupling agent is not particularly limited, and examples thereof include silane coupling agents having a vinyl group such as vinyltrichlorosilane and vinyltriethoxysilane; silane coupling agents having an epoxy group such as 3-glycidoxypropyltrimethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; silane coupling agents having an amino group such as 3-aminopropyltrimethoxysilane and N-2-(aminoethyl)-3-aminopropyltriethoxysilane; and titanate-based coupling agents. These coupling agents may be used alone or in combination of two or more. The content of the coupling agent in the thermosetting resin film is preferably 0.01 to 5% by mass. If the content of the coupling agent in the thermosetting resin film is 0.01% by mass or more, the surfaces of the aggregate and the filler tend to be sufficiently covered, and if it is 5% by mass or less, the generation of excess coupling agent tends to be suppressed.

[0047] A thermosetting resin film can be obtained by applying a thermosetting resin composition containing the above components to a carrier film, removing any unnecessary organic solvent, and drying by heating. The carrier film is not particularly limited, and examples thereof include organic films such as polyethylene terephthalate (PET), biaxially oriented polypropylene (OPP), polyethylene, polyvinyl fluorate, and polyimide; films of copper, aluminum, and alloys of these metals; and films in which the surface of these organic films or metal films has been treated with a release agent for release.

[0048] Preferable examples of FRP precursors obtained by the manufacturing method of this embodiment include prepregs. When a thermosetting resin film is used as the resin film, the resulting FRP precursor is sufficiently thermoset, i.e., C-staged, to produce FRP. Here, C-staged refers to bringing the material into the C-stage state defined by JIS K6900 (1994). The FRP obtained in this manner has high thermal conductivity and excellent heat resistance due to the high filler content, and also effectively suppresses blurring (an indicator of the formability of an FRP precursor).Furthermore, when the filler is an inorganic filler, it also has excellent low thermal expansion properties.

[0049] Furthermore, a metal-clad laminate can be produced by preparing one sheet of the FRP precursor obtained in this embodiment or by stacking 2 to 20 sheets and arranging metal foil on one or both sides of the stack. For example, the metal foil used in laminates for electrical insulating materials can be used. The metal-clad laminate has a configuration in which metal foil is provided on one or both sides of the laminate configuration described above. The metal for the metal foil is preferably copper, gold, silver, nickel, platinum, molybdenum, ruthenium, aluminum, tungsten, iron, titanium, chromium, or an alloy containing at least one of these metal elements, and copper is more preferred. The laminate molding conditions are, for example, a temperature of 100 to 250°C, a pressure of 0.2 to 10 MPa, and a heating time of 0.1 to 5 hours, using a multi-stage press, a multi-stage vacuum press, a continuous molding machine, an autoclave molding machine, or the like. [Example]

[0050] The present embodiment will now be described in more detail with reference to the following examples, but these examples do not limit the present disclosure.

[0051] [Example 1] <Preparation of Resin Varnish 1 for Pre-Coating Process> 100 parts by weight of phenol novolac epoxy resin (N-660; manufactured by DIC Corporation) and 60 parts by weight of cresol novolac resin (KA-1165; manufactured by DIC Corporation) were dissolved in 30 parts by weight of cyclohexane and 200 parts by weight of methyl ethyl ketone by thorough stirring. 5 parts by weight of amorphous silica (AEROSIL200; manufactured by AEROSIL Corporation) as a filler, 1 part by weight of coupling agent (A-187; manufactured by Momentive Performance Materials), and 1.4 parts by weight of isocyanate masked imidazole (G8009L; manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) as a curing accelerator were added and dissolved and dispersed by stirring to prepare Resin Varnish 1 with a solids concentration of 42% by weight.

[0052] <Preparation of Thermosetting Resin Film A> 100 parts by weight of phenol novolac epoxy resin (N-660; manufactured by DIC Corporation) and 60 parts by weight of cresol novolac resin (KA-1165; manufactured by DIC Corporation) were dissolved in 15 parts by weight of cyclohexane and 130 parts by weight of methyl ethyl ketone by thorough stirring. 180 parts by weight of aluminum hydroxide (CL-303; manufactured by Sumitomo Chemical Co., Ltd.) as a filler, 1 part by weight of coupling agent (A-187; manufactured by Momentive Performance Materials Co., Ltd.), and 2.5 parts by weight of isocyanate-mask imidazole (G8009L; manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) as a curing accelerator were added and dissolved and dispersed by stirring to obtain thermosetting resin varnish A with a solids concentration of 70% by weight. This thermosetting resin varnish A was applied to a 580 mm wide PET film (G-2; manufactured by Teijin DuPont Films Co., Ltd.) to a coating width of 525 mm and a thickness of 50 μm after drying, and then dried at 130°C to produce thermosetting resin film A. The minimum melt viscosity temperature of the produced thermosetting resin film A was measured using a rheometer (AR-200ex; manufactured by TA Instruments Japan, φ20 mm jig) at a temperature rise rate of 3°C / min, and was found to be 124°C.

[0053] (Pre-coating process) Next, the resin varnish 1 was diluted with a mixed solvent of methyl ethyl ketone and cyclohexanone (methyl ethyl ketone:cyclohexanone=10:1 (mass ratio)), and then mixed with glass cloth (basis weight 209 g / m 2 The coating was applied to a substrate (IPC#7628, substrate width 530 mm: manufactured by Nanya Plastics Co., Ltd.), and then the solvent was removed by drying at 175°C in a hot air dryer to obtain primed glass cloth α with a solids content of 8 mass %. The mass of the solids contained in the primed glass cloth α can be calculated from the difference between the mass of the primed glass cloth α and the mass of the glass cloth aggregate. The minimum melt viscosity temperature of the resin impregnated into the prepared primer glass cloth α was measured using a rheometer (AR-200ex; TA Instruments Japan, φ20 mm jig) at a heating rate of 3°C / min, and was found to be 133°C. (Film pressure welding process) The primed glass cloth α was sandwiched between thermosetting resin films A, and the aggregate was pressure-impregnated with the thermosetting resin film A using a pressure-heating roll at a roll temperature of 110°C, a linear pressure of 0.2 MPa, and a speed of 1.0 m / min. However, the surface of the thermosetting resin film A that contacts the aggregate was preheated to a surface temperature of 130°C by a halogen heater 30 mm in front of the pressure-heating roll (based on the center of the heating surface), and the aggregate was also preheated to a surface temperature of 145°C before the pressure-impregnation. Thereafter, the mixture was cooled on a cooling roll and wound up to prepare FRP precursor A, which is a so-called prepreg.

[0054] [Example 2] An FRP precursor B, which is a so-called prepreg, was produced in the same manner as in Example 1, except for the following changes. (Changes) Instead of producing thermosetting resin film A with a thickness of 50 μm after drying, a thermosetting resin film (referred to as "thermosetting resin film B"; minimum melt viscosity: 131°C) was produced so that the thickness after drying would be 40 μm, and this was used instead of thermosetting resin film A. Glass cloth (basis weight 209g / m 2 , IPC#7628, substrate width 530 mm: Nanya Plastics Co., Ltd.) with glass cloth (basis weight 48 g / m 2 , IPC#1080, substrate width 530mm: manufactured by Nitto Boseki Co., Ltd. Instead of obtaining primed glass cloth α with a solids content of 8 mass%, a primed glass cloth (hereinafter referred to as "primed glass cloth β"; the minimum melt viscosity of the resin in primed glass cloth β was 138°C) was prepared by adjusting the solids content to 25 mass%, and this was used instead of primed glass cloth α. During preheating, the surface temperature of the thermosetting resin film B was adjusted to 120°C, and the surface temperature of the aggregate was adjusted to 130°C.

[0055] [Example 3] An FRP precursor C, which is a so-called prepreg, was produced in the same manner as in Example 1, except for the following changes. (Changes) Instead of producing thermosetting resin film A with a thickness of 50 μm after drying, a thermosetting resin film (referred to as "thermosetting resin film C"; minimum melt viscosity 127°C) was produced so that the thickness after drying would be 20 μm, and this was used instead of thermosetting resin film A. Instead of obtaining primed glass cloth α with a solids content of 8% by mass, a primed glass cloth (referred to as primed glass cloth γ; the minimum melt viscosity of the resin in primed glass cloth γ was 126°C) was prepared by adjusting the solids content to 33% by mass, and this was used instead of primed glass cloth α.

[0056] [Comparative Example 1] In Example 1, the pre-coating step was not performed [i.e., instead of the primed glass cloth α, a glass cloth (basis weight 209 g / m 2 An FRP precursor W was prepared in the same manner as above, except that a 530 mm wide base material (IPC#7628, manufactured by Nan-A Plastics Co., Ltd.) was used as it was.

[0057] Comparative Example 2 In Example 2, the pre-coating step was not performed [i.e., instead of the primed glass cloth β, a glass cloth (basis weight 48 g / m 2 The same procedure was carried out except that the substrate (IPC#1080, substrate width 530 mm: manufactured by Nitto Boseki Co., Ltd.) was used as is, and FRP precursor X was produced.

[0058] [Reference example 1] In Example 2, instead of producing thermosetting resin film B having a thickness of 40 μm after drying, a thermosetting resin film (referred to as "thermosetting resin film 1"; minimum melt viscosity 130°C) was used so as to have a thickness of 45 μm after drying, and glass cloth (basis weight 48 g / m 2 , IPC#1080, substrate width 530 mm: manufactured by Nitto Boseki Co., Ltd.) instead of glass cloth (basis weight 24 g / m 2 FRP precursor Y was produced by the same procedure as above, except that the pre-coating step was not carried out using a 530 mm wide substrate (manufactured by Nitto Boseki Co., Ltd., IPC#1037).

[0059] The resin varnish 1 and all thermosetting resin films are summarized in Table 1 below, the glass cloth used in each example is summarized in Table 2, and the conditions for producing the FRP precursor in each example are summarized in Table 3 below. In addition, resin was collected from the surface of the FRP precursor prepared in each example, and the minimum melt viscosity was measured using a rheometer (AR-200ex; manufactured by TA Instruments Japan, φ20 mm jig) at a heating rate of 3°C / min. The results are summarized in Table 4. [Table 1]

[0060] [Table 2]

[0061] [Table 3]

[0062] [Table 4]

[0063] [Evaluation method] The FRP precursor obtained in each example was subjected to the following measurements and evaluations. The measurement and evaluation methods in Examples 1 and 3 and Comparative Example 1 are different from those in Example 2, Comparative Example 2 and Reference Example 1, and will be described in order.

[0064] (1. Measurement and Evaluation Methods for Examples 1 and 3 and Comparative Example 1) First, each FRP precursor produced in Examples 1 and 3 and Comparative Example 1 was cut to a length of 530 mm, and four of each was stacked. Copper foil (GTS-MP-18, manufactured by Furukawa Electric Co., Ltd.) was laminated on both sides of the stack, and the stack was sandwiched between SUS end plates. The stack was heated and molded by holding the product pressure at 3.0 MPa and the product temperature at 185°C for 70 minutes to produce a copper-clad laminate for evaluation with a thickness of 0.8 mm. The measurements and evaluations were carried out according to the following methods.

[0065] (1-1) Evaluation of solder heat resistance The copper-clad laminates for evaluation were subjected to a soldering heat resistance test in accordance with JIS C6481 (1996) 5.5, and the appearance of the samples after soldering was visually observed and evaluated according to the following criteria. The results are shown in Table 5. A: Swelling has occurred. C: No swelling occurs.

[0066] (1-2) Evaluation of formability The copper foils on both sides of the copper-clad laminate for evaluation were etched with an acidic iron chloride solution containing hydrochloric acid, and the appearance of the surface of the laminate after etching was visually observed and evaluated according to the following criteria. The results are shown in Table 5. A: No fading is visible. C: Blurring is observed.

[0067] (1-3) Measurement of thermal conductivity The thermal conductivity of the etched laminate prepared in the above "(1-2) Evaluation of formability" was measured according to JIS R1611 (2010) 6.2 flash method. The results are shown in Table 5.

[0068] (2. Measurement and Evaluation Methods for Example 2, Comparative Example 2, and Reference Example 1) Next, each of the FRP precursors produced in Example 2, Comparative Example 2, and Reference Example 1 was cut to a length of 530 mm. Then, an inner layer pattern as shown in Fig. 6.4-19 in JPCA-UB-01 7.5.5 was formed on a 510mm square copper clad laminate (MCL-E-679FG, 0.2mm thick, 35μm thick copper foil on both sides, manufactured by Showa Denko Materials Co., Ltd.), and the copper surface was then roughened (CZ-8101, etching amount (gravimetric method) 1.5μm, manufactured by MEC Co., Ltd.) to produce an inner layer substrate. One piece of the FRP precursor cut to a length of 530 mm was placed on each side of the inner layer substrate, and copper foil (GTS-MP-12: manufactured by Furukawa Electric Co., Ltd.) was placed on the outside, then sandwiched between SUS end plates and held at a product pressure of 2.5 MPa and a maximum temperature of 185°C for 90 minutes to produce a 0.4 mm thick four-layer copper-clad laminate. The pattern shown in Fig. 6.4-19 in JPCA-UB-01 7.5.5 was also formed on the outer layer to obtain a multilayer printed wiring board (four-layer board).

[0069] (2-1) Evaluation of solder heat resistance A multilayer printed wiring board (four-layer board) was tested in accordance with JPCA-UB-01 7.5.5.1 at a solder bath temperature of 288°C. After the test, the appearance of the sample was visually inspected and evaluated according to the following criteria. The results are shown in Table 5. A: Swelling has occurred. C: No swelling occurs.

[0070] (2-2) Evaluation of formability The copper foil of the outermost layer of a multilayer printed wiring board (four-layer board) was removed with an acidic iron chloride solution containing hydrochloric acid, and the embedding property (formability) of the inner layer pattern in the FRP precursor was visually observed and evaluated according to the following criteria. The results are shown in Table 5. A: No fading is visible. C: Blurring is observed.

[0071] [Table 5]

[0072] In Table 5, Examples 1 and 3 can be compared with Comparative Example 1, and Example 2, Comparative Example 2 and Reference Example 1 can be compared. The FRP precursors obtained by the manufacturing methods of Examples 1 to 3 have excellent solder heat resistance and moldability. This is presumably because there is no local increase in the filler ratio of the resin layer near the glass cloth surface, and the viscosity and flowability are not increased, which prevents deterioration of moldability during lamination. On the other hand, the FRP precursor obtained by the manufacturing method of Comparative Example 1 was insufficient in solder heat resistance and moldability compared to the FRP precursors obtained by the manufacturing methods of Examples 1 and 3 (see Table 5). Also, the FRP precursor obtained by the manufacturing method of Comparative Example 2 was insufficient in solder heat resistance and moldability compared to the FRP precursor obtained by the manufacturing method of Example 2 (see Table 5). Incidentally, the FRP precursor obtained by the manufacturing method of Reference Example 1 has excellent solder heat resistance and moldability. However, as shown in Table 2, when the bulk thickness of the aggregate is small, there tends to be no decrease in solder heat resistance and moldability, and the effect of this embodiment is more easily seen when the bulk thickness of the aggregate is large. [Explanation of symbols]

[0073] 100 Pre-coating device 200 FRP precursor manufacturing equipment used after the pre-coating process 2. Aggregate delivery device 2' Pre-coated aggregate delivery device 3 Resin film feeding device 4 Protective film removal mechanism 5 Protective film winding device 6 Sheet heating and pressure device (film pressure welding means) 7. Sheet pressurized cooling device 8. Pre-coated aggregate winding device 9 FRP precursor winding device 10a Preheating mechanism 10b Preheating mechanism 11a Preheating mechanism 11b Preheating mechanism 17 Dryer 40 Aggregate 40a One surface of the aggregate (one of both surfaces of the aggregate) 40b The other surface of the aggregate (the other of both surfaces of the aggregate) 41 Pre-coated aggregate 41a One surface of pre-coated aggregate (one of both surfaces of aggregate) 41b The other surface of the pre-coated aggregate (the other of both surfaces of the aggregate) 50 Resin film with protective film 52 Protective Film 54 Resin film 54a Aggregate side film surface 60 FRP precursor

Claims

1. Pre-applying a resin varnish containing a filler of 5% by volume or less of the solid content to the sheet-shaped aggregate; After the pre-application, a pair of resin films each having a filler content of 30% by volume or more are melt-attached to both surfaces of the aggregate; A method for producing an FRP precursor, comprising:

2. The method for producing an FRP precursor according to claim 1 , wherein the amount of resin varnish used in the pre-coating satisfies the following formula (1): [Equation 1]

3. The method for producing an FRP precursor according to claim 1 or 2, wherein the melt-bonding step includes the following film pressure bonding. Film pressing: Under normal pressure, one of the two surfaces of one of the pair of resin films, which is the surface facing the aggregate, is pressed against one of the two surfaces of the aggregate, and the other of the two surfaces of the other of the pair of resin films, which is the surface facing the aggregate, is pressed against the other of the two surfaces of the aggregate, to obtain an FRP precursor.

4. The method for producing an FRP precursor according to claim 3, further comprising preheating the aggregate-side film surface of both surfaces of the resin film before the film pressure welding.

5. The method for producing an FRP precursor according to claim 3 or 4, further comprising preheating both surfaces of the aggregate before the film pressure welding.

6. The method for producing an FRP precursor according to any one of claims 1 to 5, wherein the aggregate has a bulk thickness of 30 µm or more.

7. The method for producing an FRP precursor according to any one of claims 1 to 6, wherein the average particle size of the filler contained in the resin varnish is 0.1 to 10 µm.

8. The method for producing an FRP precursor according to any one of claims 1 to 7, wherein the resin film is a thermosetting resin film.

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