Patent Description:
A fiber-reinforced resin molding configured comprising FRP (Fiber Reinforced Plastic), which is a type of composite material, is known from the prior art (refer, for example, to <CIT>).

<CIT> discloses a carbon fiber composite material molding obtained by sandwiching a core layer of nonwoven fabric between two carbon fiber layers, which form skin layers, to form a stacked body, and impregnating the stacked body with an impregnating resin, followed by curing. <CIT> discloses a structure having a core layer and a pair of skin layers. The pair of skin layers has fibers and a matrix resin that covers the fibers. The skin layers join to both sides of the core layer. <CIT> discloses a structure which has a core and a pair of skin layers. The core has syntactic foam and is sandwiched by a pair of sheets.

In the carbon fiber composite material molding described above, the skin layers and the core layer are joined only by resin, and the joining force between the skin layers and the core layer is low; consequently, when a load is applied to the carbon fiber composite material molding, there is the possibility that the skin layers and the core layer between the layers will separate.

Thus, the object of the present invention is to prevent the skin layer from separating from the core layer by increasing the joining force between the skin layer and the core layer.

A first feature of the present invention is a fiber-reinforced resin molding comprising a core layer comprising a nonwoven fabric and impregnating resin that has been impregnated into the nonwoven fabric, and a pair of skin layers comprising fibers and a matrix resin that covers the fibers. The skin layers have recesses that are formed in the core layer side surfaces and in which some of the fibers in the matrix resin are exposed, and portions of the nonwoven fabric and the impregnating resin penetrate the recesses.

A second aspect of the present invention is a method for producing a fiber-reinforced resin molding. The production method includes a step for forming recesses in which some of the fibers in the matrix resin the skin layers are exposed to the core layer side surfaces, and a step for disposing a nonwoven fabric between a pair of the skin layers, causing portions of the nonwoven fabric and the impregnating resin to penetrate the recesses, and joining the skin layers and the core layer in that state.

According to the present invention, it is possible to prevent separation of the skin layers from the core layer by increasing the joining force between the skin layers and the core layer.

An embodiment of the present invention will be described in detail below with reference to the drawings.

A fiber-reinforced resin molding <NUM> according to an embodiment of the present invention will now be described with reference to <FIG>.

The fiber-reinforced resin molding <NUM> can be applied, for example, to vehicle component members, such as a hood (bonnet), a bumper, a trunk lid, a rear gate, a fender panel, a side body panel, and a roof panel. In addition, the fiber-reinforced resin molding <NUM> is not limited to vehicle component members and can be applied to various types of component members.

The fiber-reinforced resin molding <NUM> comprises a core layer <NUM> and a pair of skin layers <NUM>, <NUM> that are joined to both surfaces of the core layer <NUM>, as illustrated in <FIG> and <FIG>.

The core layer <NUM> is a nonwoven fabric layer comprising a nonwoven fabric <NUM> and an impregnating resin <NUM> that has been impregnated in the nonwoven fabric <NUM>. The thickness of the core layer <NUM> is, for example, about <NUM>-<NUM>. The nonwoven fabric <NUM> is formed from known fibers, such as cotton, rayon, nylon, polyester, polypropylene, and aramid fibers. The impregnating resin <NUM> is formed from a thermosetting resin, such as epoxy resin, unsaturated polyester resin, vinyl ester resin, and phenol resin. In addition, the impregnating resin <NUM> may be formed from a thermoplastic resin, such as polyamide resin, polyolefin resin, dicyclopentadiene resin, and polyurethane resin.

The skin layers <NUM> are made up of a fiber layer comprising fibers <NUM> and a matrix resin <NUM> that covers the fibers <NUM>. That is, the skin layers <NUM> are what is referred to as an FRP (fiber-reinforced resin). The thicknesses of the skin layers <NUM> are, for example, about <NUM> to <NUM>. The fibers <NUM> can be formed from various fibers, such as carbon fiber, glass fiber, and aramid fiber (Kevlar fiber). The matrix resin <NUM> can be formed from thermosetting resin, such as epoxy resin, unsaturated polyester resin, vinyl ester resin, and phenol resin. In addition, the matrix resin <NUM> can be formed from a thermoplastic resin, such as polyamide resin, polyolefin resin, dicyclopentadiene resin, and polyurethane resin.

The impregnating resin <NUM> of the core layer <NUM> and the matrix resin <NUM> of the skin layers <NUM> can be of the same or of different types. From the standpoint of enhancing the joining force between the core layer <NUM> and the skin layers <NUM>, the impregnating resin <NUM> of the core layer <NUM> and the matrix resin <NUM> of the skin layers <NUM> are preferably resins that have high affinity.

The skin layers <NUM> have a plurality of recesses <NUM> formed on side surface <NUM> facing the core layer <NUM> such that portions of the fibers <NUM> in the matrix resin <NUM> are exposed. The matrix resin <NUM> of the skin layers <NUM> and the impregnating resin <NUM> of the core layer <NUM> are joined (bonded), in a state in which portions of the nonwoven fabric <NUM> and the impregnating resin <NUM> have penetrated the recesses <NUM>. Thus, the fiber-reinforced resin molding <NUM> has a plurality of mixed regions <NUM> which is formed in the joint portion <NUM> between the core layer <NUM> and the skin layers <NUM> and in which the nonwoven fabric <NUM> and the fibers <NUM> are mixed.

The recesses <NUM> and the mixed regions <NUM> are arranged at intervals in the longitudinal direction and the lateral direction on the surfaces of the skin layers <NUM>, as illustrated in <FIG>. In the figure, the recesses <NUM> and the mixed regions <NUM> are arranged at equal intervals, but no limitation is imposed thereby, and the intervals need not be equal.

In addition, the positions of the recesses <NUM> and the mixed regions <NUM> in the in-plane direction of the skin layers <NUM> (direction that is parallel to the surface) are asymmetrical relative to the core layer <NUM> between one and the other of the pair of skin layers <NUM>, <NUM>, as illustrated in <FIG>. That is, the recesses <NUM> and the mixed regions <NUM> are arranged in different locations between one and the other of the pair of skin layers <NUM>, <NUM>. However, no limitation is imposed thereby; the positions of the recesses <NUM> and the mixed regions <NUM> in the in-plane direction of the skin layer <NUM> can be symmetrical relative to the core layer <NUM> between one and the other of the pair of skin layers <NUM>, <NUM>.

Next, a method for producing the fiber-reinforced resin molding <NUM> according to the present embodiment will be described.

First, a wax <NUM> is applied to a sheet or a bundle of fiber <NUM>, as illustrated in <FIG>, in randomly distributed fashion and the applied wax <NUM> is cured and hardened.

Thermoplastic resins such as polyvinyl alcohol (PVA), polyethylene (PE), or polypropylene (PP), for example, may be used as the wax <NUM>. Polyethylene and polypropylene have relatively low melting points; therefore, when polyethylene or polypropylene is used as the wax <NUM>, it is necessary to set the injection temperature of the matrix resin <NUM> to be less than or equal to the melting points of polyethylene and polypropylene.

Next, the fibers <NUM> are placed in the mold and the matrix resin <NUM> is injected into the mold to impregnate the fibers <NUM> with the matrix resin <NUM>, as illustrated in <FIG>. Then, the impregnated matrix resin <NUM> is cured and hardened to prepare the skin layer <NUM>.

Next, the wax <NUM> is melted with warm water or a solvent to form recesses <NUM> on the skin layer <NUM>, as illustrated in <FIG>.

That is, in the present embodiment, the lost wax method is used to form the recesses <NUM> on the skin layer <NUM>.

Next, the nonwoven fabric <NUM> is stacked between a pair of skin layers <NUM>, <NUM> to prepare a stacked body <NUM>, as illustrated in <FIG>.

Next, the stacked body <NUM> is placed in a mold, impregnating resin <NUM> is injected into the mold, and the nonwoven fabric <NUM> is impregnated with the impregnating resin14, as illustrated in <FIG>. In this step to inject the impregnating resin <NUM> into a mold, portions of the nonwoven fabric <NUM> and the impregnating resin <NUM> are made to penetrate each recess <NUM>, and the fibers <NUM> that are exposed due to the removal of the wax <NUM> become entangled with the nonwoven fabric <NUM>. Then, the impregnating resin <NUM> is cured and hardened to prepare a fiber-reinforced resin molding <NUM>.

That is, in the present embodiment, the RTM molding (Resin Transfer Molding) method is used to mold the stacked body <NUM>.

The action and effects of the present embodiment will be described below.

In the fiber-reinforced resin molding <NUM> according to the present embodiment, the matrix resin <NUM> of the skin layer <NUM> and the impregnating resin <NUM> of the core layer <NUM> are joined in a state in which portions of the nonwoven fabric <NUM> and the impregnating resin <NUM> have penetrated the recesses <NUM>. That is, mixed regions <NUM>, in which the nonwoven fabric <NUM> and the fibers <NUM> are mixed, are formed in the joint portion <NUM> between the core layer <NUM> and the skin layer <NUM>. Thus, it is possible to enhance the joining force between the skin layer <NUM> and the core layer <NUM> and to reduce the possibility that the skin layer <NUM> and the core layer <NUM> will separate between the layers, even if a load is applied to the fiber-reinforced resin molding <NUM>.

Therefore, according to the fiber-reinforced resin molding <NUM> of the present embodiment, it is possible to prevent the skin layer <NUM> from separating from the core layer <NUM> by increasing the joining force between the skin layer <NUM> and the core layer <NUM>.

(<NUM>) The positions of the recesses <NUM> in the in-plane direction of the skin layer <NUM> are asymmetrical relative to the core layer <NUM> between one and the other of the pair of skin layers <NUM>, <NUM>.

Thus, it is possible to shift the positions of the mixed regions <NUM>, in which the nonwoven fabric <NUM> and the fibers <NUM> are mixed, in the in-plane direction of the skin layer <NUM> between one and the other of the pair of skin layers <NUM>, <NUM>, and to thereby prevent the generation of locations with low densities of the nonwoven fabric <NUM> in the core layer <NUM>.

(<NUM>) The method for producing a fiber-reinforced resin molding <NUM> according to the present embodiment comprises a step (Step <NUM>) for forming recesses <NUM> in which portions of the fibers <NUM> in the matrix resin <NUM> are exposed on side surfaces <NUM> of the skin layer <NUM> facing the core layer <NUM>, and a step (Step <NUM>) for disposing the nonwoven fabric <NUM> between the pair of skin layers <NUM>, <NUM>, causing some of the nonwoven fabric <NUM> and impregnating resin <NUM> to penetrate the recesses <NUM>, and joining the skin layer <NUM> and the core layer <NUM> in that state.

As a result, the matrix resin <NUM> of the skin layer <NUM> and the impregnating resin <NUM> of the core layer <NUM> are joined in a state in which some of the nonwoven fabric <NUM> and the impregnating resin <NUM> have penetrated the recesses <NUM>. That is, mixed regions <NUM>, in which the nonwoven fabric <NUM> and the fibers <NUM> are mixed, are formed in the joint portion <NUM> between the core layer <NUM> and the skin layer <NUM>. Thus, it is possible to enhance the joining force between the skin layer <NUM> and the core layer <NUM> and to reduce the possibility that the skin layer <NUM> and the core layer <NUM> will separate between the layers, even if a load is applied to the fiber-reinforced resin molding <NUM>.

Therefore, according to the method for producing a fiber-reinforced resin molding <NUM> of the present embodiment, it is possible to prevent the skin layer <NUM> from separating from the core layer <NUM> by increasing the joining force between the skin layer <NUM> and the core layer <NUM>.

(<NUM>) The recesses <NUM> are formed using a lost wax method.

Thus, it is possible to precisely form the recesses <NUM> on the skin layer <NUM>.

A method for producing a fiber-reinforced resin molding <NUM> according to another embodiment will be described with reference to <FIG>.

First, wax <NUM> is applied to a sheet or a bundle of fibers <NUM>, as illustrated in <FIG>, in randomly distributed fashion and the applied wax <NUM> is cured and hardened.

Next, the fibers <NUM> are placed in the mold and the matrix resin <NUM> is injected into the mold to impregnate the fibers <NUM> with the matrix resin <NUM>, as illustrated in <FIG>. The impregnated matrix resin <NUM> is then cured and hardened to prepare the skin layer <NUM>.

Next, a nonwoven fabric-containing adhesive (nonwoven fabric <NUM> that has been impregnated with impregnating resin <NUM> in advance) is stacked between a pair of skin layers <NUM>, <NUM> to prepare a stacked body <NUM>, as illustrated in <FIG>.

Next, the stacked body <NUM> is placed in a mold, and a fiber-reinforced resin molding <NUM> is formed inside the mold, as illustrated in <FIG>. In this step to form the fiber-reinforced resin molding <NUM> in a mold, portions of the nonwoven fabric <NUM> and the impregnating resin <NUM> are made to penetrate each recess <NUM>, and the fibers <NUM> that are exposed due to the removal of the wax <NUM> become entangled with the nonwoven fabric <NUM>. The impregnating resin <NUM> is cured and hardened to prepare a fiber-reinforced resin molding <NUM>.

In this embodiment, a hot press molding method or an autoclave molding method may be used as the method for forming the fiber-reinforced resin molding <NUM>.

Claim 1:
A fiber-reinforced resin molding (<NUM>) comprising:
a core layer (<NUM>) comprising a nonwoven fabric (<NUM>) and an impregnating resin (<NUM>) that has been impregnated in the nonwoven fabric (<NUM>); and
a pair of skin layers (<NUM>) comprising fibers (<NUM>) and a matrix resin (<NUM>) that covers the fibers (<NUM>), and joined to both sides of the core layer (<NUM>); wherein
the skin layers (<NUM>) have recesses (<NUM>) formed on a core layer side surface such that portions of the fibers (<NUM>) in the matrix resin (<NUM>) are exposed, and
portions of the nonwoven fabric (<NUM>) and the impregnating resin (<NUM>) have entered the recesses (<NUM>).