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EP-4523875-B1 - METHOD FOR MANUFACTURING FRP PRECURSOR AND METHOD FOR MANUFACTURING FRP

EP4523875B1EP 4523875 B1EP4523875 B1EP 4523875B1EP-4523875-B1

Inventors

  • UMEZAKI SHOTA
  • SASAKI RYOTA
  • SAITOH TAKESHI
  • NAKAMURA YUKIO

Dates

Publication Date
20260506
Application Date
20230426

Claims (5)

  1. A method for producing an FRP precursor by adhering a thermosetting resin film to at least one surface of an aggregate that is in a form of a sheet, the method comprising: after the adhesion, transporting the FRP precursor while imparting a tension of 1.5 to 5.5 N/25mm to the FRP precursor.
  2. The method for producing the FRP precursor according to claim 1, wherein a thickness of the aggregate is 25 µm or less.
  3. The method for producing the FRP precursor according to claim 1 or 2, wherein a tensile strength of the aggregate is 20 to 150 N/25mm.
  4. The method for producing the FRP precursor according to any one of claims 1 to 3, wherein the adhesion of the thermosetting resin film to at least one surface of the aggregate that is in a form of a sheet is conducted under an atmospheric pressure.
  5. A method for producing an FRP, wherein the method comprises curing of the FRP precursor obtained by the production method according to any one of claims 1 to 4.

Description

[Technical Field] The present invention relates to a method for producing an FRP precursor as well as a method for producing an FRP. [Background Art] FRP (Fiber Reinforced Plastics) is a composite material using an aggregate having a high modulus, such as fibers, in which the aggregate is incorporated into a mother material (matrix) such as a plastic in order to enhance the strength thereof. Therefore, FRP is a cheap, light, and highly durable composite material utilizing its superior weatherability, lightness, and resistances to heat and chemicals. By utilizing these characteristics, FRP is used in a wide variety of fields. For example, FRP is used in a wide variety of fields such as structural materials of housing equipment, a marine vessel, a vehicle, and an airplane because FRP can be molded and has high strength. It is also used in a field such as an electric device because of its electric non-conductance. Illustrative examples of the FRP production method include: (1) an RTM (Resin Transfer Molding) method in which a resin is charged into a matched mold having an aggregate spread therein; (2) a Hand Lay-up (HLU) method and a spray-up method in which a resin is laminated in a multiple fashion onto a spread aggregate with defoaming the resin; and (3) an SMC (Sheet Molding Compound) press method in which an aggregate and a resin are pre-mixed and made to a form of a sheet, and then this is press-molded in a mold. When the FRP is used for a printed wiring board, thickness of the FRP for the printed wiring board is required to be thinner than the thickness of the FRP for other uses. In addition, the FRP for the printed wiring board is required to have a high quality specification, such as absence of a void and a narrow acceptable range of variance in its thickness after FRP molding. Accordingly, many FRP for the printed wiring board are produced by the Hand Lay-up (HLU) method. The Hand Lay-up method is the production method in which a varnish having a resin dissolved therein is applied to an aggregate by using a coating machine, which is then followed by drying it in order to remove a solvent and cure it with heating. Industrially, a vertical coating method is used in which an aggregate is transported into a vessel in which a resin varnish is charged, which is then followed by pulling up a FRP precursor having the resin varnish impregnated therein by a Roll-to-Roll method into a vertical drying oven (see Patent Document 1). In recent years, however, in an electronic part used in electronic equipment, from the viewpoint of convenience in use and the like, further reduction in the weight and size thereof is required. Under such circumstances, a printed wiring board used in an electronic part is also reduced in the thickness and size thereof, so that a wiring pattern is made finer and an insulating layer is made thinner as well. Therefore, a thinner FRP is required, which in turn requires a thinner aggregate that is contained in the FRP. When the aggregate is made thinner in the vertical coating method, upon pulling-up the FRP precursor having the resin varnish impregnated therein by a Roll-to-Roll method, the weight of the FRP precursor outweighs the allowable load of the aggregate thereby occasionally resulting in a cut of the FRP precursor into piece. On the other hand, as for the method other than the vertical coating method, a method has been known in which a resin film of a thermosetting resin is prepared in advance, which is followed by adhering an aggregate to the resin film and further followed by heating it to produce an FRP precursor (see Patent Document 2). [Citation List] [Patent Document] Patent Document 1: Japanese Patent Laid-Open Publication No. H01-272416Patent Document 2: International Patent Laid-Open Publication No. 2018/181513 [Summary of the Invention] [Problems to be Solved by the Invention] The inventors of the present invention carried out an extensive investigation on the method described in Patent Document 2; then, as a result, it was found that in the FRP, which is a cured product of the FRP precursor, especially in the FRP having copper foil, the production condition of the FRP precursor has an effect on "size-change rate" before and after "copper foil etching and drying by heating". In general, there is no significant problem with regard to the size-change rate of the FRP when the rate is constant without varying among the lots. However, a small size-change rate itself is prone to lower the variance among the lots, so that it is preferable to lower the size-change rate in an industrial production. Here, the lot means the products that are produced under the same condition. Accordingly, an object of the present invention is to provide a method for producing the FRP precursor causing a small size-change rate after copper foil etching and drying by heating of the FRP as well as a method for producing the FRP. [Means for Solving the Problems] The inventors of the present invention