JP6009399B2 - Fiber-reinforced composite and method for producing the same - Google Patents

Description

  The present invention relates to a fiber-reinforced composite having excellent impact resistance and a method for producing the same.

  A fiber reinforced plastic (FRP) in which a plastic is reinforced by a reinforced fiber such as carbon fiber or glass fiber is known. In recent years, FRP is lightweight and has excellent rigidity, and thus has become an indispensable component in various fields such as aircraft, automobiles, ships, and buildings.

  Vehicles such as airplanes, automobiles, and ships are required to improve fuel efficiency in order to reduce the burden on the global environment, and therefore further weight reduction is required for FRP. Therefore, a fiber-reinforced composite in which FRP is laminated and integrated as a skin material on at least one surface of a foam core has been proposed (for example, Patent Documents 1 and 2). By using the foam in this way, the FRP can be thinned, and it is possible to provide a fiber-reinforced composite that is large but lightweight and excellent in rigidity.

JP 2007-144919 A JP 2005-313613 A

  Fiber reinforced composites are also required to have excellent impact resistance. In order to ensure the impact resistance of the fiber reinforced composite, when the fiber reinforced composite is subjected to external impact, the fiber reinforced composite can absorb the impact energy by the elasticity of the foam, and the FRP There is a need to be able to maintain a certain shape by suppressing deformation by rigidity.

  However, in the conventional fiber reinforced composite, since the foam is flexible, when a strong impact is applied to the fiber reinforced composite, the FRP is easily deformed to generate a stress concentration portion. In some cases, the FRP breaks down as a starting point, and the fiber-reinforced composite is deformed. Therefore, the impact resistance of the conventional fiber reinforced composite is not sufficient, and improvement is desired.

  Accordingly, an object of the present invention is to provide a fiber-reinforced composite having excellent impact resistance and a method for producing the same.

The fiber reinforced composite of the present invention includes a foam including a core foam layer and a surface layer formed on both sides of the core foam layer, and a fiber reinforced plastic laminated and integrated on at least one of the surface layers. A fiber reinforced composite having a layer,
The surface layer in which the fiber reinforced plastic layer is laminated and integrated among the surface layers is formed as a harder surface foam layer than the core foam layer,
The average aspect ratio (Ac) of the bubbles contained in the core foam layer is 0.65 to 1, and the average aspect ratio (As) of the bubbles contained in the surface foam layer is 0.5 to 1. It is characterized by 0.8.

  Further, in the method for producing a fiber-reinforced composite of the present invention, a laminate in which a fiber-reinforced plastic layer forming material containing reinforcing fibers impregnated with a reinforcing synthetic resin is laminated on at least one surface of a foam, While being heated at a temperature 20 ° C. lower than the glass transition temperature of the reinforcing synthetic resin and 60 ° C. higher than the glass transition temperature of the reinforcing synthetic resin, the compression deformation rate of the foam is 1 to 45%. It has the compression process which compresses so that it may become.

  The fiber reinforced composite of the present invention can exhibit excellent impact resistance when the foam as the core material has the above-described core foam layer and surface foam layer.

It is the longitudinal cross-sectional view which showed the fiber reinforced composite_body | complex of this invention. It is sectional drawing which showed the manufacturing point of the fiber reinforced composite_body | complex of this invention. It is the schematic cross section which showed an example of the manufacturing apparatus of a synthetic resin expanded particle. It is the schematic diagram which looked at the multi-nozzle mold from the front.

  A schematic cross-sectional view of the fiber-reinforced composite A of the present invention is shown in FIG. The fiber reinforced composite A of the present invention includes a foam 1 and a fiber reinforced plastic layer 2 that is laminated and integrated on both surfaces of the foam 1. In the foam 1, the surface of the foam 1, and a portion having a dimension of 2.5% with respect to the thickness T of the foam 1 in this direction in a direction orthogonal to the surface of the foam 1. The portions in between are referred to as surface layers 1b and 1c. In the foam 1, the remaining part excluding the surface layers 1 b and 1 c is defined as a core foam layer 1 a. In FIG. 1, in a direction orthogonal to the surface of the foam 1, imaginary lines L and L represent portions connecting portions having a size of 2.5% with respect to the thickness T of the foam 1 in this direction. Indicated. Of the surface layers 1b and 1c, the surface layer in which the fiber reinforced plastic layer 2 is laminated and integrated is formed as a surface foam layer.

  In the foam, the core foam layer exhibits moderate elasticity, and thus, the core foam layer has a role of absorbing impact energy when an impact is applied to the fiber-reinforced composite. Further, in the foam, the surface foam layer is a harder layer than the core foam layer, and when an impact is applied to the fiber reinforced composite by laminating and integrating the fiber reinforced plastic layer on such a surface foam layer. The surface foam layer supports the fiber reinforced plastic layer, and has a role of highly reducing the occurrence of stress concentration due to deformation of the fiber reinforced plastic layer.

  Therefore, since the foam includes the above-described core foam layer and the surface foam layer harder than the core layer, it is possible to exhibit excellent impact energy absorption and to reduce the breakage due to deformation of the fiber reinforced plastic layer. Thus, it is possible to provide a fiber-reinforced composite with improved impact resistance. Note that the mechanism by which the effect of the present invention is obtained is not clear, and the above mechanism is a hypothesis of the present inventors. Hereinafter, the fiber reinforced composite of the present invention will be described in order.

[Foam]
The foam constituting the fiber-reinforced composite of the present invention contains a synthetic resin. The synthetic resin preferably has a polar group such as cyano group, hydroxy group (hydroxyl group), carbonyl group, amino group, epoxy group, halogen atom, oxo group, and phenyl group. By using a synthetic resin having a polar group, the foam containing this and the fiber-reinforced plastic layer can be firmly integrated. Thereby, when an impact is applied to the fiber reinforced composite, it is possible to reduce the peeling between the foam and the fiber reinforced plastic layer, thereby further improving the impact resistance of the fiber reinforced composite.

  Specific examples of the synthetic resin used for the foam include polycarbonate resin, acrylic resin, thermoplastic polyester resin, polymethacrylimide resin, polystyrene resin, and polypropylene resin. In addition, a synthetic resin may be used independently or 2 or more types may be used together. Especially, since a foam and a fiber reinforced plastic layer can be integrated more firmly, a thermoplastic polyester resin and an acrylic resin are preferable and an acrylic resin is more preferable.

  The thermoplastic polyester resin is a high molecular weight linear polyester obtained as a result of a condensation reaction between a dicarboxylic acid and a dihydric alcohol. Of the thermoplastic polyester resins, aromatic polyester resins are preferred.

  The aromatic polyester resin is a polyester containing an aromatic dicarboxylic acid component and a diol component, such as polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polycyclohexanedimethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, etc. And polyethylene terephthalate is preferred. In addition, an aromatic polyester resin may be used independently or 2 or more types may be used together.

  In addition to the aromatic dicarboxylic acid component and the diol component, the aromatic polyester resin includes, for example, a tricarboxylic acid such as trimellitic acid such as trimellitic acid, a tetracarboxylic acid such as pyromellitic acid, or a polyvalent carboxylic acid such as tricarboxylic acid or its anhydride. Products, triols such as glycerin, and trihydric or higher polyhydric alcohols such as tetraols such as pentaerythritol may be contained as constituent components.

  Polyethylene terephthalate may be crosslinked by a crosslinking agent. Known crosslinking agents are used, and examples thereof include acid dianhydrides such as pyromellitic anhydride, polyfunctional epoxy compounds, oxazoline compounds, and oxazine compounds. In addition, a crosslinking agent may be used independently or 2 or more types may be used together.

(Core foam layer)
The foam includes a core foam layer and a surface layer formed on both surfaces of the core foam layer.

  Although the average aspect-ratio (Ac) of the bubble contained in the core foam layer is limited to 0.65-1, 0.7-1 are preferable and 0.75-1 are more preferable. The core foam layer containing air bubbles having an average aspect ratio within the above range has appropriate elasticity and hardness, so that when impact is applied to the fiber reinforced composite, impact energy is transferred to the surface of the core foam layer. It is possible to absorb while diffusing in the direction.

  In the present invention, the aspect ratio of the bubbles contained in the core foam layer and the surface layer (surface foam layer) can be measured as follows. First, the fiber reinforced composite is cut in the thickness direction, and the cut surface is photographed at 200 times using a scanning electron microscope. Next, in the photographed image obtained by this, as shown in FIG. 1, the foam 1 in the foam 1 in the direction perpendicular to the surface of the foam 1 and the surface of the foam 1. The portions between the portion having a dimension of 2.5% with respect to the thickness T of 1 are defined as surface layers 1b and 1c. In the foam 1, the remaining part excluding the surface layers 1 b and 1 c is defined as a core foam layer 1 a. In FIG. 1, in a direction orthogonal to the surface of the foam 1, portions connecting portions having a dimension of 2.5% with respect to the thickness T of the foam 1 in this direction are phantom dotted lines L, L It showed in. The surface layer in which the fiber reinforced plastic layer 2 is laminated and integrated among the surface layers 1b and 1c is a surface foam layer.

  Next, the aspect ratio is measured for 30 bubbles contained in the core foam layer 1a and the surface layers (surface foam layers) 1b and 1c, respectively, and the arithmetic average value is defined as the average aspect ratio. The aspect ratio is a value obtained by measuring the major axis and minor axis of the bubble cross section and dividing the minor axis by the major axis. Then, two arbitrary points having the maximum mutual distance are selected on the outer contour line of the bubble cross section, and the distance between the two points is defined as “the major diameter of the bubble”. Also, any two points where the mutual distance is maximum are selected from any two points where the straight line perpendicular to the major axis of the bubble and the outer contour line of the bubble cross section intersect, and the distance between the two points is expressed as “ The short diameter of the bubble ”.

  In addition, when the bubble which the cross section is exposed in the foam 1 surface exists, such a bubble is excluded from the measurement object of an aspect ratio. For example, when the unfoamed skin is cut and removed from the foam 1, there is a possibility that bubbles having a cross-section exposed on the surface of the foam. In addition, bubbles existing across the virtual line L2 are also excluded from the aspect ratio measurement target.

  The average major axis of the bubbles contained in the core foam layer is preferably 0.05 to 0.8 mm, and more preferably 0.08 to 0.7 mm. The core foam layer in which the average major axis of the bubbles is too short has a too high hardness, so that the core foam layer may not be able to absorb impact energy sufficiently. In addition, the core foam layer having an average long diameter of bubbles that is too long becomes too flexible, and therefore, when a strong impact is applied to the fiber reinforced composite, the fiber reinforced plastic layer may be easily deformed and broken.

  In addition, the average major axis of the bubbles contained in the core foam layer and the surface layer (surface foam layer) is as described above, and the 30 bubbles contained in the core foam layer and the surface layer (surface foam layer), respectively. It can be obtained by measuring the major axis of the bubbles and calculating the arithmetic mean value thereof.

The apparent density of the core foam layer is preferably 0.01 to 0.9 g / cm ³ , and more preferably 0.02 to 0.7 g / cm ³ . If the apparent density of the core foam layer is too low, when a strong impact is applied to the fiber reinforced composite, a stress concentration part occurs in the core foam layer due to the buckling of the bubbles contained in the core foam layer, This may cause the fiber reinforced plastic layer to be easily deformed and broken. Further, in the core foam layer having an apparent density that is too high, there is a possibility that the hardness is too high and the impact energy cannot be sufficiently absorbed.

  In the present invention, the apparent density of the core foam layer and the surface foam layer (surface layer) described later is obtained by cutting out only the core foam layer or the surface foam layer (surface layer) from the foam, The surface layer is a value measured according to JIS K7222.

  5-35 are preferable and, as for the durometer hardness of a core foaming layer, 10-35 are more preferable. If the durometer hardness of the core foam layer is too low, when a strong impact is applied to the fiber reinforced composite, a stress concentration part occurs in the core foam layer due to the buckling of the bubbles contained in the core foam layer, This may cause the fiber reinforced plastic layer to be easily deformed and broken. Further, in the core foam layer having a durometer hardness that is too high, the impact energy may not be sufficiently absorbed.

  The durometer hardness of the core foam layer and the surface foam layer (surface layer) described later is a value measured 5 seconds after pressurizing with a load of 1 kgf in accordance with JIS K6253. And only a core foam layer or a surface foam layer (surface layer) is cut out from a foam, 30 durometer hardness is measured about a core foam layer or a surface foam layer (surface layer), and the arithmetic mean value is set to a core foam layer or The durometer hardness of the surface foam layer (surface layer). The durometer hardness can be measured using a hardness meter (for example, trade name “HARDNESS TESTER GS-720N TYPE D” manufactured by Teclock Corporation).

(Surface foam layer)
A surface layer is formed on each of the upper and lower surfaces in the thickness direction of the core foam layer described above. Of the surface layers, the surface layer in which the fiber reinforced plastic layers are laminated and integrated is formed as the surface foam layer. By interposing the surface foam layer between the core foam layer and the fiber reinforced plastic layer in this way, the surface foam layer can support the fiber reinforced plastic layer and reduce the breakage due to deformation of the fiber reinforced plastic layer. it can.

  As shown in FIG. 1, the surface foam layers 1b and 1c do not need to be formed on both surfaces of the core foam layer 1a, but are formed at least on the surface side where the fiber reinforced plastic layer 2 is laminated and integrated in the foam. It only has to be done. Therefore, when the fiber reinforced plastic layer 2 is laminated and integrated only on the upper surface of the foam 1, the core foam layer 1a out of the surface layers 1b and 1c formed on the upper and lower surfaces of the core foam layer 1a, respectively. It is sufficient that only the surface layer 1b formed on the upper surface is formed as a surface foam layer. In such a case, the surface layer 1c formed on the lower surface of the core foam layer 1a is not particularly limited and may be a foam layer or a non-foam layer, but is preferably a foam layer. . When the surface layer 1c formed on the lower surface of the core foam layer 1a is a foam layer, such a foam layer has the same configuration as the core foam layer or the surface foam layer (for example, the aspect ratio and average major axis of bubbles, It may have an apparent density and a durometer hardness.

  The average aspect ratio (As) of the bubbles contained in the surface foam layer is limited to 0.5 to 0.8, preferably 0.5 to 0.75, and 0.5 to 0.7. More preferred. The surface foamed layer containing bubbles having an average aspect ratio that is too small may be a brittle layer that is too hard and has reduced toughness. Such a surface foamed layer is easily cracked when impact energy is applied to the fiber reinforced composite, so that there is a possibility that the cracking of the fiber reinforced plastic layer cannot be sufficiently reduced. In addition, the surface foam layer containing air bubbles whose average aspect ratio is too large is insufficient in hardness and cannot sufficiently support the fiber reinforced plastic layer when an impact is applied to the fiber reinforced composite. There is a risk that the layer will easily deform and crack.

  In the foam, the average aspect ratio (Ac) of the bubbles contained in the core foam layer is preferably larger than the average aspect ratio (As) of the bubbles contained in the surface foam layer. In particular, the difference (Ac−As) between the average aspect ratio (Ac) of the bubbles contained in the core foam layer and the average aspect ratio (As) of the bubbles contained in the surface foam layer is 0.14 or more. Is preferable, 0.14 to 0.5 is more preferable, and 0.2 to 0.4 is particularly preferable. According to the core foam layer in which the difference (Ac-As) is within the above range, the impact resistance of the fiber-reinforced composite can be improved.

  The average major axis of the bubbles contained in the surface foam layer is preferably 0.05 to 0.7 mm, more preferably 0.05 to 0.6 mm. A surface foamed layer having an average length of bubbles that is too short becomes a hard and brittle layer, and therefore the surface foamed layer may be destroyed when a strong impact is applied to the fiber-reinforced composite. In addition, a foamed surface layer with an average long diameter of bubbles that is too long cannot provide sufficient support for the fiber reinforced plastic layer when the fiber reinforced composite is impacted due to insufficient hardness. There is a risk of easily deforming and cracking.

Apparent density of the surface foam layer is preferably 0.04~0.9g / cm ^3, more preferably 0.06~0.8g / cm ^3. In the surface foam layer having an apparent density that is too low, the hardness is insufficient and the fiber reinforced plastic layer may be easily deformed and broken when an impact is applied to the fiber reinforced composite. In addition, a surface foam layer having an apparent density that is too high becomes a hard and brittle layer, and easily breaks when impact energy is applied to the fiber-reinforced composite, resulting in a decrease in the impact resistance of the fiber-reinforced composite. There is.

  10-45 are preferable and, as for the durometer hardness of a surface foam layer, 15-40 are more preferable. When the surface foam layer has a durometer hardness that is too low, the hardness is insufficient and the fiber-reinforced plastic layer may be easily deformed and broken when an impact is applied to the fiber-reinforced composite. In addition, a surface foamed layer having a durometer hardness that is too high becomes a hard and brittle layer, and easily breaks when impact energy is applied to the fiber-reinforced composite, resulting in a decrease in the impact resistance of the fiber-reinforced composite. There is.

  The total thickness of the foam may be set as appropriate according to the use for which the fiber-reinforced composite is used, but is preferably 1 to 60 mm, and more preferably 2 to 50 mm.

[Fiber-reinforced plastic layer]
The fiber-reinforced plastic layer used in the fiber-reinforced composite of the present invention is formed by impregnating reinforcing fibers with a reinforcing synthetic resin.

  As shown in FIG. 1, the fiber reinforced plastic layer 2 does not need to be laminated and integrated on both surfaces of the foam 1, and the fiber reinforced plastic layer 2 is laminated and integrated on at least one surface of the foam 1. It only has to be made. The lamination of the fiber reinforced plastic layer 2 may be determined according to the use of the fiber reinforced composite A. Especially, when the impact resistance of the fiber reinforced composite A is considered, it is preferable that the fiber reinforced plastic layer 2 is laminated and integrated on each of the upper and lower surfaces in the thickness direction of the foam 1. As shown in FIG. 1, such a fiber reinforced composite A is a foam 1 including a core foam layer 1a and surface foam layers 1b and 1c formed as surface layers on both surfaces of the core foam layer 1a. And a fiber reinforced plastic layer 2 laminated and integrated with the surface foam layers 1b and 1c, respectively.

  The reinforcing fibers constituting the fiber reinforced plastic layer include inorganic fibers such as glass fibers, carbon fibers, silicon carbide fibers, alumina fibers, Tyranno fibers, basalt fibers, ceramic fibers; metal fibers such as stainless fibers and steel fibers; Organic fibers such as aramid fiber, polyethylene fiber, polyparaphenylene benzoxador (PBO) fiber; and boron fiber. Reinforcing fibers may be used alone or in combination of two or more. Among these, carbon fiber, glass fiber, and aramid fiber are preferable, and carbon fiber is more preferable. These reinforcing fibers have excellent mechanical strength despite being lightweight.

  The reinforcing fiber is preferably used as a reinforcing fiber substrate processed into a desired shape. Examples of the reinforcing fiber base material include woven fabrics, knitted fabrics, nonwoven fabrics, and face materials obtained by binding (sewing) fiber bundles (strands) obtained by aligning reinforcing fibers in one direction with yarns. . Examples of the weaving method include plain weave, twill weave and satin weave. Examples of the yarn include synthetic resin yarn such as polyamide resin yarn and polyester resin yarn, and stitch yarn such as glass fiber yarn.

  The fiber reinforced base material may be used without laminating only one fiber reinforced base material, or a plurality of fiber reinforced base materials may be laminated and used as a laminated fiber reinforced base material. As a laminated fiber reinforced base material in which a plurality of fiber reinforced base materials are laminated, (1) a laminated fiber reinforced base material in which only one kind of fiber reinforced base material is prepared and these fiber reinforced base materials are laminated, 2) A plurality of types of fiber reinforced base materials are prepared, a laminated fiber reinforced base material obtained by laminating these fiber reinforced base materials, and (3) a fiber bundle (strand) in which the reinforced fibers are aligned in one direction is bound with a thread ( Prepare a plurality of face materials made by stitching), superimpose these face materials so that the fiber directions of the fiber bundles are different from each other, and integrate the superposed face materials with a thread (sewing) A laminated fiber reinforced base material is used. Examples of the yarn include synthetic resin yarns such as polyamide resin yarns and polyester resin yarns, and stitch yarns such as glass fiber yarns.

  The fiber reinforced plastic layer is formed by impregnating a reinforcing fiber into a reinforcing fiber. The reinforcing fibers can be bonded and integrated by the impregnated reinforcing synthetic resin. As the reinforcing synthetic resin impregnated into the reinforcing fiber, either a thermoplastic resin or a thermosetting resin can be used, and a thermosetting resin is preferably used. The thermosetting resin is not particularly limited. For example, epoxy resin, unsaturated polyester resin, phenol resin, melamine resin, polyurethane resin, silicon resin, maleimide resin, vinyl ester resin, cyanate ester resin, maleimide resin and cyanide Examples thereof include a resin obtained by prepolymerizing an acid ester resin, and an epoxy resin and a vinyl ester resin are preferable since they are excellent in heat resistance, impact absorption or chemical resistance. The thermosetting resin may contain additives such as a curing agent and a curing accelerator. In addition, a thermosetting resin may be used independently or 2 or more types may be used together.

  The thermoplastic resin is not particularly limited, and examples thereof include olefin resins, polyester resins, thermoplastic epoxy resins, amide resins, thermoplastic polyurethane resins, sulfide resins, acrylic resins, and the like. Of these, polyester resins and thermoplastic epoxy resins are preferred because of their excellent adhesiveness or adhesiveness between the reinforcing fibers constituting the fiber-reinforced plastic layer. In addition, a thermoplastic resin may be used independently or 2 or more types may be used together.

  The thermoplastic epoxy resin may be a polymer or copolymer of epoxy compounds having a linear structure, or a copolymer of an epoxy compound and a monomer that can be polymerized with the epoxy compound. And a copolymer having a linear structure. Specifically, as the thermoplastic epoxy resin, for example, bisphenol A type epoxy resin, bisphenol fluorene type epoxy resin, cresol novolac type epoxy resin, phenol novolac type epoxy resin, cyclic aliphatic type epoxy resin, long chain aliphatic type An epoxy resin, a glycidyl ester type epoxy resin, a glycidylamine type epoxy resin and the like can be mentioned, and a bisphenol A type epoxy resin and a bisphenol fluorene type epoxy resin are preferable. In addition, a thermoplastic epoxy resin may be used independently or 2 or more types may be used together.

  Examples of the thermoplastic polyurethane resin include a polymer having a linear structure obtained by polymerizing diol and diisocyanate. Examples of the diol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, and the like. Diols may be used alone or in combination of two or more. Examples of the diisocyanate include aromatic diisocyanate, aliphatic diisocyanate, and alicyclic diisocyanate. Diisocyanate may be used independently or 2 or more types may be used together. In addition, a thermoplastic polyurethane resin may be used independently or 2 or more types may be used together.

  The content of the reinforcing synthetic resin in the fiber reinforced plastic layer is preferably 20 to 70% by weight, and more preferably 30 to 60% by weight. If the content of the reinforcing synthetic resin is too small, the binding properties between the reinforcing fibers and the adhesion between the fiber reinforced plastic layer and the foam are insufficient, and the mechanical strength of the fiber reinforced plastic layer and the fiber reinforced composite There is a possibility that the impact resistance cannot be sufficiently improved. Moreover, when there is too much content of the synthetic resin for reinforcement | strengthening, the mechanical strength of a fiber reinforced plastic layer may fall, and there exists a possibility that the impact resistance of a fiber reinforced composite cannot fully be improved.

  The thickness of the fiber reinforced plastic layer is preferably 0.02 to 2 mm, and more preferably 0.05 to 1 mm. The fiber reinforced plastic layer having a thickness within the above range is excellent in mechanical strength despite being lightweight.

Basis weight of the fiber-reinforced plastic layer is preferably ^{50~4000g / m 2, 100~1000g / m} 2 is more preferable. The fiber reinforced plastic layer having a basis weight within the above range is excellent in mechanical strength despite being lightweight.

  In the fiber reinforced composite of the present invention, the foam as the core material has the core foam layer and the surface foam layer described above, so that the impact resistance is improved while maintaining the rigidity of the fiber reinforced plastic layer. ing. Accordingly, such a fiber reinforced composite is not particularly limited, but is suitably used as a component member such as an aircraft, an automobile, a ship, and a building, or a casing of an electronic device.

  The specific absorbed energy amount of the fiber reinforced composite is preferably 160 J / g or more, and more preferably 200 J / g or more. A fiber reinforced composite having a too low specific absorption energy may not have excellent impact resistance.

  In addition, the measurement of the specific absorbed energy amount of a fiber reinforced composite can be performed as follows. First, by cutting the fiber reinforced composite, a test piece having a size and shape of 100 mm in length, 15 mm in width, and 10 mm in height is produced. Next, a load-displacement curve is created for the test piece in accordance with JIS K7221 under conditions of a load cell 1000N and a test speed of 20 mm / min. The value obtained by calculating the load-displacement integral value until the test piece breaks based on the obtained load-displacement curve is taken as the absorbed energy [J], and this absorbed energy [J] A value obtained by dividing by weight [g] is defined as a specific absorbed energy amount [J / g].

[Production method]
As a method for producing the fiber-reinforced composite of the present invention, a known thermoforming method can be used, and examples thereof include a vacuum forming method and a pressure forming method. Examples of thermoforming methods that apply vacuum forming method and pressure forming method include straight forming method, drape forming method, plug assist forming method, plug assist reverse draw forming method, air slip forming method, snapback forming method, reverse draw method. Examples include molding methods, plug assist / air slip molding methods, match molding methods, and thermoforming methods that combine these molding methods. Good appearance even when fiber reinforced plastic layer forming materials with poor moldability are used. Since a simple fiber reinforced composite can be obtained, the match molding method is preferable.

  An example of the point which manufactures a fiber reinforced composite using a thermoforming method is demonstrated concretely. As a method for producing a fiber reinforced composite of the present invention, a laminate in which a fiber reinforced plastic layer forming material including a reinforced fiber impregnated with a reinforcing synthetic resin is laminated on at least one surface of a foam, While being heated at a temperature 20 ° C. lower than the glass transition temperature of the reinforcing synthetic resin and 60 ° C. higher than the glass transition temperature of the reinforcing synthetic resin, the compression deformation rate of the foam is 1 to 45%. A method having a compressing step of compressing as described above is preferably used. In addition, the heating temperature of a laminated body means the surface temperature of the fiber reinforced plastic layer forming material of a laminated body.

  Since the foam contains bubbles, the thermal conductivity is low, so the center of the foam is difficult to be heated. Therefore, in the compression step, the synthetic resin contained in the surface portion of the foam can be moderately softened by heating the laminate at a predetermined temperature. In the compression step, the reinforcing synthetic resin impregnated in the reinforcing fibers can be appropriately softened by heating the laminate at a predetermined temperature. And by compressing a laminated body, performing such a heating, a fiber reinforced plastic layer forming material can press the foam surface entirely, deform | transforming along a foam surface. This makes it possible to form a surface foam layer containing bubbles having a desired average aspect ratio on the surface portion of the foam by slightly crushing and flattening the bubbles contained in the surface portion of the foam. .

  When the uncured thermosetting resin is contained in the reinforcing synthetic resin impregnated into the reinforcing fiber, preferably, the fiber reinforced plastic layer forming material is adjusted by adjusting the heating of the laminate in the compression step. Maintain the fluidity without curing the uncured thermosetting resin, deform the fiber reinforced plastic layer forming material along the foam surface, and then adjust the heating time of the laminate. By advancing the curing reaction of the uncured thermosetting resin, the thermosetting resin can be cured and the reinforcing fibers can be bonded and integrated with each other, whereby the thermosetting resin is bonded to the reinforcing fibers on the foam. A fiber-reinforced plastic layer impregnated with can be formed. When a thermoplastic resin is used as the reinforcing synthetic resin to be impregnated into the reinforcing fiber, the thermoplastic resin is cooled and solidified by cooling the laminated body after the laminated body is heated in the compression step. By reinforcing and bonding the reinforcing fibers, a fiber reinforced plastic layer formed by impregnating the reinforcing fibers with the thermoplastic resin on the foam can be formed.

  As a manufacturing method of a foam, a well-known manufacturing method can be used. Specifically, (1) The synthetic resin foam particles are filled in a mold, the synthetic resin foam particles are heated and foamed with a heat medium such as hot water or steam, and the foamed particles are generated by the foaming pressure of the synthetic resin foam particles. A method of producing a foam having a desired shape by fusing together, (2) a foaming agent such as a chemical foaming agent or a physical foaming agent by supplying synthetic resin to an extruder A method of producing a foam by melting and kneading in the presence of an extrusion machine and extruding and foaming from the extruder (extrusion foaming method), (3) supplying a synthetic resin and a chemical foaming agent to the extruder to be below the decomposition temperature of the chemical foaming agent Examples thereof include a method of producing a foamed product by melt-kneading and producing a foamable resin molded product from an extruder and foaming the foamable resin molded product. Especially, according to the in-mold foam molding method of (1), a foam having a desired shape can be easily produced.

  As a method for producing the synthetic resin foamed particles used in the above-mentioned in-mold foam molding method (1), (I) the synthetic resin is supplied into the extruder and melt-kneaded in the presence of a physical foaming agent. A method of producing synthetic resin foam particles by cutting the synthetic resin extrudate from the attached nozzle mold while extruding and cooling, and (II) supplying the synthetic resin into the extruder and in the presence of a physical foaming agent. A method of producing a synthetic resin expanded particle by cutting and blowing this synthetic resin extrudate at predetermined intervals by extrusion-foaming from a nozzle die attached to an extruder by melt-kneading, (III) Synthetic resin is supplied into the extruder, melt-kneaded in the presence of a physical foaming agent, extruded and foamed from an annular die or T-die attached to the extruder to produce a foamed sheet, and this foamed sheet is cut Synthetic resin by And a method of manufacturing a foam particles.

  An example of a method for producing such synthetic resin expanded particles will be described. First, an example of a production apparatus used when producing synthetic resin expanded particles by extrusion foaming will be described. In FIG. 3, reference numeral 10 denotes a nozzle mold attached to the front end of the extruder. As shown in FIGS. 3 and 4, a plurality of nozzle outlet portions 11, 11... Are formed on the same virtual circle C at equal intervals on the front end surface 10 a of the nozzle mold 10. The nozzle mold attached to the front end of the extruder is not particularly limited as long as the synthetic resin raw material does not foam in the nozzle.

  In the front end face 10a of the nozzle mold 10 surrounded by the nozzle outlet portions 11, 11,..., The rotary shaft 20 is disposed in a state of projecting forward. 20 is connected to a driving member 30 such as a motor through a front portion 41a of a cooling drum 41 constituting the cooling member 40.

  Further, one or a plurality of rotary blades 50, 50... Are integrally provided on the outer peripheral surface of the rear end portion of the rotary shaft 20, and all the rotary blades 50 are nozzles when rotating. The mold 10 is always in contact with the front end face 10a. If the rotary shaft 20 is integrally provided with a plurality of rotary blades 50, 50 ..., the plurality of rotary blades 50, 50 ... are equally spaced in the circumferential direction of the rotary shaft 20. Each is arranged. 4 shows a case where four rotary blades 50, 50... Are integrally provided on the outer peripheral surface of the rotary shaft 20 as an example.

  As the rotary shaft 20 rotates, the rotary blades 50, 50... Are constantly in contact with the front end surface 10a of the nozzle mold 10 to form nozzle outlet portions 11, 11,. It moves on the virtual circle C, and the synthetic resin extruded foam extruded from the outlet portions 11, 11.

  A cooling member 40 is disposed so as to surround at least the front end portion of the nozzle mold 10 and the rotary shaft 20. The cooling member 40 has a front circular front part 41a having a larger diameter than the nozzle mold 10 and a cylindrical peripheral wall part 41b extending rearward from the outer peripheral edge of the front part 41a. And a bottom cylindrical cooling drum 41.

  Further, a supply port 41c for supplying the cooling liquid 42 is formed in a portion of the peripheral wall portion 41b of the cooling drum 41 corresponding to the outside of the nozzle mold 10 so as to penetrate between the inner and outer peripheral surfaces. Yes. A supply pipe 41 d for supplying the coolant 42 into the cooling drum 41 is connected to the outer opening of the supply port 41 c of the cooling drum 41.

  The cooling liquid 42 is configured to be supplied obliquely forward along the inner peripheral surface of the peripheral wall portion 41b of the cooling drum 41 through the supply pipe 41d. Then, the coolant 42 spirals along the inner peripheral surface of the peripheral wall portion 41b of the cooling drum 41 due to the centrifugal force accompanying the flow velocity when being supplied from the supply pipe 41d to the inner peripheral surface of the peripheral wall portion 41b of the cooling drum 41. Go forward as you draw. Then, the coolant 42 gradually spreads in the direction perpendicular to the traveling direction while traveling along the inner peripheral surface of the peripheral wall portion 41b, and as a result, the inner surface of the peripheral wall portion 41b in front of the supply port 41c of the cooling drum 41 is increased. The peripheral surface is configured to be entirely covered with the coolant 42.

  The cooling liquid 42 is not particularly limited as long as the synthetic resin foam particles can be cooled, and examples thereof include water, alcohol and the like, but water is preferable in consideration of the treatment after use.

  A discharge port 41e is formed on the lower surface of the front end portion of the peripheral wall portion 41b of the cooling drum 41 so as to penetrate between the inner and outer peripheral surfaces. A discharge pipe 41f is connected to the outer opening of the discharge port 41e. The synthetic resin foam particles and the coolant 42 are configured to be continuously discharged through the discharge port 41e.

  Using such a manufacturing apparatus, the synthetic resin is supplied to an extruder and melt-kneaded in the presence of a foaming agent, and then the synthetic resin is extruded and foamed from a nozzle mold 10 attached to the front end of the extruder. The resulting extruded foam can be cut with the rotary blade 50 to produce synthetic resin particles. When using a cross-linking agent, supply the synthetic resin and cross-linking agent to an extruder, melt and knead in the presence of a foaming agent to cross-link the synthetic resin with the cross-linking agent, and then attach it to the front end of the extruder. The extruded foam obtained by extruding and foaming the synthetic resin from the nozzle mold 10 can be cut with the rotary blade 50 to produce synthetic resin particles.

  Examples of the chemical foaming agent include azodicarbonamide, dinitrosopentamethylenetetramine, hydrazoyl dicarbonamide, and sodium bicarbonate. In addition, a chemical foaming agent may be used independently or 2 or more types may be used together.

  Physical foaming agents include, for example, propane, normal butane, isobutane, normal pentane, isopentane, hexane and other saturated aliphatic hydrocarbons, ethers such as dimethyl ether, methyl chloride, 1,1,1,2-tetrafluoroethane, 1 , 1-difluoroethane, chlorofluorocarbons such as monochlorodifluoromethane, carbon dioxide, nitrogen and the like, dimethyl ether, propane, normal butane, isobutane and carbon dioxide are preferred, propane, normal butane and isobutane are more preferred, and normal butane and isobutane are preferred. Particularly preferred. In addition, a physical foaming agent may be used independently or 2 or more types may be used together.

  In the method of the present invention, a laminate in which a fiber reinforced plastic layer forming material including reinforcing fibers impregnated with a synthetic resin is laminated on at least one surface of the above-described foam is used. The surface of the foam on which the fiber reinforced plastic layer forming material is laminated may be determined according to the use of the obtained fiber reinforced composite, and is not particularly limited. Therefore, the fiber reinforced plastic layer forming material may be laminated only on one surface of the foam. Especially, when the impact resistance of the obtained fiber reinforced composite is considered, it is preferable to laminate | stack a fiber reinforced plastic layer forming material on both surfaces of a foam, respectively.

  In addition, about the synthetic resin for reinforcement | strengthening used for the foam used for a laminated body and a fiber reinforced plastic layer formation material, and a reinforced fiber, the synthetic resin for reinforcement | strengthening used for the foam in the fiber reinforced composite body mentioned above or a fiber reinforced plastic layer Since these are the same as those of the reinforcing fiber, detailed description thereof is omitted here.

  The foaming ratio of the foam used for the laminate is preferably 1.3 to 60 times, more preferably 1.5 to 30 times, and more preferably 5 to 20 times. The foam having an expansion ratio within the above range has an appropriate thermal conductivity, and thereby forms a surface foam layer containing bubbles having a desired aspect ratio on the surface of the foam in the compression step. It becomes easy. In the present invention, the foaming magnification of the foam is measured according to JIS K7222.

  In the fiber reinforced plastic layer forming material, the reinforcing fiber is impregnated with the reinforcing synthetic resin. The method of impregnating the reinforcing synthetic resin in the reinforcing fiber is not particularly limited. For example, (1) a method of immersing the reinforcing fiber in the reinforcing synthetic resin and impregnating the reinforcing synthetic resin in the reinforcing fiber, (2) A method in which a reinforcing synthetic resin is applied to the reinforcing fiber and the reinforcing fiber is impregnated with the reinforcing synthetic resin, and (3) a sheet containing the reinforcing synthetic resin is laminated on the reinforcing fiber substrate and then heated. Examples thereof include a method in which the reinforcing synthetic resin contained in the sheet is impregnated into the reinforcing fiber constituting the reinforcing fiber substrate by pressurization. In the methods (1) and (2), the reinforcing fiber is used as the reinforcing fiber base, and the reinforcing fiber base is immersed in the reinforcing synthetic resin or the reinforcing synthetic resin is applied to the reinforcing fiber base. By doing so, the reinforcing fiber constituting the reinforcing fiber base can be impregnated with the reinforcing synthetic resin.

  When a reinforcing fiber is impregnated with a thermosetting resin as a reinforcing synthetic resin, it is preferable to impregnate an uncured thermosetting resin. The order of impregnation of the reinforcing synthetic resin is not particularly limited, and the reinforcing fibers may be impregnated with the reinforcing synthetic resin after the reinforcing fibers are laminated on both sides of the foam. After the impregnation, the reinforcing fiber may be laminated on the foam.

  A commercially available reinforcing fiber plastic layer forming material including a reinforcing fiber substrate or a reinforcing fiber substrate impregnated with a reinforcing synthetic resin can be used. The reinforcing fiber substrate is commercially available from Mitsubishi Rayon under the trade name “Pyrofil”, for example. Further, a fiber reinforced plastic layer forming material including a reinforced fiber base material impregnated with a thermosetting resin is commercially available from Mitsubishi Rayon Co., Ltd. under the trade name “Pyrofil Prepreg”. A fiber reinforced plastic layer forming material including a reinforced fiber base material impregnated with a thermoplastic resin is commercially available from Nagase Chemtech under the trade name “NNGF60-03s”.

  In the method of the present invention, before the compression step, the laminate is at least 120 ° C. lower than the glass transition temperature of the reinforcing synthetic resin impregnated in the reinforcing fibers and above the glass transition temperature of the reinforcing synthetic resin. It is preferable to carry out a preheating step of heating at a temperature lower than 20 ° C. By carrying out such a preheating step, the surface portion of the foam is moderately softened on the surface on which the fiber-reinforced plastic layer forming material is laminated, and then the compression step is carried out to obtain the surface portion of the foam. It is possible to more efficiently press and flatten the bubbles contained in the surface and easily form a surface foam layer containing bubbles having a desired average aspect ratio. In addition, according to the preheating step, the reinforcing synthetic resin contained in the reinforcing fiber is moderately softened, and the conformability between the reinforcing synthetic resin and the reinforcing fiber is improved. It is also possible to form a fiber reinforced plastic layer excellent in mechanical strength in which reinforcing fibers are firmly bonded and integrated. Further, by appropriately softening the reinforcing synthetic resin contained in the fiber reinforcement in the preheating step, the softened reinforcing synthetic resin enters the irregularities on the foam surface, thereby obtaining an anchor effect. It is also possible to firmly bond and integrate the reinforced plastic layer and the foam. Therefore, it is possible to further improve the impact resistance of the fiber-reinforced composite obtained by performing such a preheating step.

  The heating temperature of the laminate in the preheating step is (Tg−120) ° C. or higher and (Tg + 80) ° C. when the glass transition temperature of the reinforcing synthetic resin impregnated in the reinforcing fiber is “Tg (° C.)”. Is less than (Tg−100) ° C. and less than (Tg + 70) ° C., more preferably (Tg−100) ° C. to (Tg + 60) ° C. If the heating temperature of the laminate is too low, the compatibility between the reinforcing synthetic resin and the reinforcing fibers will be reduced, and bubbles will be generated in the resulting fiber-reinforced plastic layer, which will reduce the impact resistance of the fiber-reinforced composite. There is a risk of doing. Moreover, when the heating temperature of a laminated body is too high, the bubble in a foam may be crushed and there exists a possibility that the impact resistance of a fiber reinforced composite may fall.

  In the present invention, the glass transition temperature of the thermoplastic resin is measured by the method described in JIS K7121: 1987 “Method for measuring plastic transition temperature”. However, the sampling method and temperature conditions are as follows. Using a differential scanning calorimeter device, about 6 mg of the sample is filled so that there is no gap at the bottom of the aluminum measurement container, and the sample is cooled from 30 ° C. to −40 ° C. for 10 minutes under a nitrogen gas flow rate of 20 mL / min. The sample was heated from -40 ° C. to 290 ° C. (1st Heating), held at 290 ° C. for 10 minutes, and then cooled from 290 ° C. to −40 ° C. (Cooling) for 10 minutes. The DSC curve was obtained when the temperature was raised from −40 ° C. to 290 ° C. (2nd Heating). In addition, all the temperature increase rates and temperature decrease rates are performed at 10 ° C./min, and alumina is used as a reference material. In the present invention, the glass transition point means an intermediate point glass transition temperature obtained from a DSC curve obtained in the 2nd Heating process. The midpoint glass transition temperature is obtained from JIS K7121: 1987 (9.3 “How to Obtain Glass Transition Temperature”). In addition, as a differential scanning calorimeter apparatus, the differential scanning calorimeter apparatus marketed by the SII nanotechnology company by the brand name "DSC6220 type | mold" can be used, for example.

  In the present invention, the glass transition temperature of the thermosetting resin refers to a temperature measured in the following manner. When measuring the glass transition temperature of a thermosetting resin, it is necessary to harden the thermosetting resin in advance. The curing temperature of the thermosetting resin is set to an exothermic peak temperature ± 10 ° C. measured in JIS K7121: 1987. The curing time of the thermosetting resin is 60 minutes as a guide. When the exothermic peak of the thermosetting resin after curing is measured according to JIS K7121: 1987, the curing is complete if no exothermic peak is observed. The glass transition temperature of the thermosetting resin is measured in the manner described later using the cured thermosetting resin. In addition, the detailed measuring method of the exothermic peak temperature used as the standard of the curing temperature of the thermosetting resin mentioned above is as follows. The exothermic peak temperature of the thermosetting resin is measured by the method described in JIS K7121: 1987 “Method for measuring plastic transition temperature”. However, the sampling method and temperature conditions are as follows. Using a differential scanning calorimeter device, about 6 mg of the sample is filled so that there is no gap at the bottom of the aluminum measurement container, alumina is used as a reference material under a nitrogen gas flow rate of 20 mL / min, and the sample is heated from 30 ° C. to 220 ° C. The temperature is raised to 5 ° C. at a rate of 5 ° C./min. In the present invention, the exothermic peak temperature of the thermosetting resin is a value obtained by reading the temperature at the peak top at the first temperature rise. In addition, as a differential scanning calorimeter apparatus, the differential scanning calorimeter apparatus marketed by the SII nanotechnology company by the brand name "DSC6220 type | mold" can be used, for example.

  The glass transition temperature of the thermosetting resin is a temperature measured in accordance with 9.3 “How to obtain glass transition temperature” in JIS K7121 (1987) “Method for measuring plastic transition temperature”. Specifically, 6 mg of a thermosetting resin after curing for measuring the glass transition temperature is taken as a sample. Using a differential scanning calorimeter device, the sample was heated from 30 ° C. to 200 ° C. at a rate of temperature increase of 20 ° C./min in a nitrogen gas flow at a flow rate of 20 mL / min. Hold for a minute. Thereafter, the sample is quickly taken out from the apparatus and cooled to 25 ± 10 ° C., and then the sample is again heated to 200 ° C. at a heating rate of 20 ° C./min under a nitrogen gas flow rate of 20 mL / min in the apparatus. The glass transition temperature (intermediate point) is calculated from the DSC curve obtained when the temperature is raised. In the measurement, alumina is used as a reference material. In addition, as a differential scanning calorimeter apparatus, the differential scanning calorimeter apparatus marketed by the SII nanotechnology company by the brand name "DSC6220 type | mold" can be used, for example.

  Moreover, it is preferable not to compress a laminated body at a preheating process. By carrying out the preheating step without compressing the laminate, it is possible to efficiently exclude bubbles contained in the fiber reinforced plastic layer forming material, etc., and foam the reinforcing synthetic resin contained in the reinforced fibers. High penetration can be achieved by unevenness on the body surface.

  Next, in the method of the present invention, the laminate is at least 20 ° C. lower than the glass transition temperature of the reinforcing synthetic resin impregnated in the reinforcing fibers and 60 ° C. higher than the glass transition temperature of the reinforcing synthetic resin. A compression step of compressing the foam so that the compression deformation rate of the foam is 1 to 45% is performed while heating at a temperature below.

  The heating temperature of the laminate in the compression step is limited to (Tg−50) ° C. to (Tg + 60) ° C. when the glass transition temperature of the reinforcing synthetic resin impregnated in the reinforcing fibers is “Tg”. (Tg-40) ° C to (Tg + 40) ° C is preferred. If the heating temperature of the laminate is too low, the fiber reinforced plastic layer forming material and the foam cannot be sufficiently bonded and integrated in the compression process, and thus a fiber reinforced composite having excellent impact resistance can be obtained. There is no fear. Moreover, when the heating temperature of a laminated body is too high, the bubble of a foam may be crushed and there exists a possibility that the impact resistance of a fiber reinforced composite may fall.

  In the compression step, the compression of the laminate is preferably adjusted so that the compression deformation rate of the foam is 1 to 45%, and more preferably adjusted so that the compression deformation rate of the foam is 1 to 40%. preferable. If the compression deformation rate of the foam is too small, there is a possibility that the foam surface cannot be flattened by sufficiently pressing the foam surface with the fiber reinforced plastic layer forming material. Moreover, if the compression deformation rate of the foam is too high, the entire foam may be deformed.

The compression deformation rate of the foam is defined as the thickness T ₁ of the foam before the compression step (before the pre-heating step when the pre-heating step is performed) and the thickness T ₂ of the foam after the compression step. The measurement is performed at 10 arbitrary points, and the compression deformation rate of the foam at each measurement point is calculated based on the following formula. The arithmetic average value of the compression deformation rate at each measurement point is calculated as the compression deformation rate of the foam. And The thickness T ₂ of the foam is the dimension of the foam portion where the thickness T ₁ of the foam is measured.
Compression deformation rate of foam (%)
= 100 × (| T ₁ (mm) −T ₂ (mm) |) / | T ₁ (mm) |

  The compression deformation rate of the foam can be adjusted by adjusting the degree of pressurization to the laminate. For example, as a method of adjusting the compressive deformation rate of the foam, a method of adjusting the pressing force applied to the laminate by using the pressing member by sandwiching the laminated body in the thickness direction thereof is used. At this time, it is preferable to arrange the spacers on the outer side of the laminated body, for example, outside both end portions in the width direction or the length direction of the laminated body. By adjusting the height of the spacer, it is possible to easily adjust the degree of pressurization to the laminate and the compression deformation rate of the foam.

  In the case of using a spacer, the spacer may be disposed outside the laminated body. For example, the spacer may be disposed at least outside both ends in the width direction or the length direction of the laminated body, and both ends in the width direction of the laminated body. You may arrange | position both to the part outer side and the both ends outer side in a length direction.

  As described above, the fiber reinforced body is formed by heat-compressing the laminate in the compression step, so that the foam is laminated and integrated on at least one surface of the foam, and the reinforcing fiber is impregnated with the reinforcing synthetic resin. A fiber reinforced composite comprising a plastic layer is obtained.

  After performing the compression process as described above, the fiber reinforced plastic layer is laminated and integrated only on one surface of the foam by cutting the foam contained in the laminate at the center in the thickness direction. The resulting fiber reinforced composite can also be obtained.

  Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

Example 1
A flat rectangular foam containing an acrylic resin A and having an unfoamed skin on the surface (expanding ratio 10 times, product name “Formac # 1000 grade” manufactured by Sekisui Plastics Co., Ltd.) is used as a raw foam. Prepared. The skin was cut off from the foam to expose the cell cross section on the surface of the foam. The thickness of the foam 1 ′ after the skin was cut and removed was 20 mm.

On the other hand, a fiber reinforced plastic layer forming material (thickness 0.3 mm, weight per unit area) in which 40% by weight of an uncured epoxy resin (glass transition temperature 128 ° C.) is impregnated into a reinforcing fiber substrate made of a twill weave made of carbon fiber : 200 g / m ² , a product name “Pyrofil Prepreg TR3523 381KMP” manufactured by Mitsubishi Rayon Co., Ltd.) was prepared. The fiber reinforced plastic layer forming material had a planar rectangular shape of 10 cm long × 30 cm wide. Then, the two fiber reinforced plastic layer forming materials were superposed so that the crossing angle between the warp length directions of the reinforcing fiber bases adjacent to each other was 90 °.

  Next, an aluminum plate is prepared, and a release agent (trade name “Chem Lease 2166” manufactured by Chem Lease Japan Co., Ltd.) is applied to the upper surface of the aluminum plate and left to stand for a day. did. In addition, in order to arrange | position the sealing material 8 and the back valve 9 which are mentioned later in the outer periphery part of the aluminum plate upper surface, the mold release process was not performed.

  As shown in FIG. 2, an aluminum plate whose upper surface has been subjected to a release treatment is used as the pressing member 3a. As shown in FIG. 2 'was placed, and foam 1' was placed on these fiber-reinforced plastic layer forming materials 2 '.

  Separately from the above, two fiber reinforced plastic layer forming materials identical to the above were prepared, and the two fiber reinforced plastic layer forming materials were superposed in the same manner as described above. These two laminated fiber reinforced plastic layer forming materials 2 'were placed on the foam 1' to produce a laminate A '.

  Next, a pair of spacers 4a and 4b were placed on the outer side of both end portions in the width direction of the multilayer body A 'on the surface of the pressing member 3a subjected to the mold release treatment. The spacers 4a and 4b were made of an aluminum plate and had a thickness of 18.2 mm. In addition, the upper surface of the spacers 4a and 4b that comes into contact with the pressing member 3b, which will be described later, was subjected to a mold release process in advance. In the same manner as described above, an aluminum plate having a release treatment on the lower surface was prepared as the pressing member 3b, and the pressing member 3b was stacked on the laminate A ′ and the spacers 4a and 4b. At this time, the release treatment surface of the pressing member 3b was in contact with the laminate A ′.

  Thereafter, on the pressing member 3b, a release film 5 (trade name “WL5200B-P” manufactured by AIRTECH) having a through hole and a breather cloth 6 (product manufactured by AIRTECH) so as to cover the entire surface of the pressing member 3b. The name “AIRWEAVE N4”) was stacked in order. The release film 5 is formed of a tetrafluoroethylene-ethylene copolymer film, and has a large number of through-holes that penetrate between both surfaces and allow the epoxy resin in the fiber-reinforced plastic layer forming material 2 ′ to pass therethrough. It was. The breather cloth 6 is formed of a non-woven fabric composed of polyester resin fibers, and can be impregnated with an epoxy resin.

  Cover the breather cloth 6 with a bagging film 7 (trade name “WL7400” manufactured by AIRTECH) and sealant tape (AIRTECH) with the sealing material 8 between the outer peripheral edge of the bagging film 7 and the pressing member 3a facing the bagging film 7. The laminate A ′ was hermetically sealed with the bagging film 7 using a product name “GS43MR”). The bagging film 7 was made of a nylon film. A back valve 9 (trade name “VAC VALVE 402A” manufactured by AIRTECH) was disposed on a part of the bagging film 7 to produce a laminated structure.

  Next, the laminated structure is supplied into the autoclave, the back valve 9 of the laminated structure is connected to a vacuum line, and the space B sealed with the bagging film 7 is passed from the laminated body A ′ to the laminated body A ′. The side surfaces were evacuated in the direction of the breather cloth 6 covering the spacers 4a and 4b, and the pressure was reduced to 0.10 MPa. Note that the decompression of the space B was continued after that.

  Thereafter, while the air present in the fiber reinforced plastic layer forming material 2 ′ is sucked and removed, the temperature inside the autoclave is increased to 90 ° C. at a temperature increase rate of 4 ° C./min. The fiber reinforced plastic layer forming material is heated for 90 minutes without compressing (preheating step), thereby softening the epoxy resin in the fiber reinforced plastic layer forming material 2 '. Acrylic contained in the surface portion of the surface of the foam 1 ′ on which the fiber reinforced plastic layer forming material 2 ′ is laminated, while deforming the fiber reinforced plastic layer forming material 2 ′ along the surface of the foam 1 ′. Resin A was softened appropriately.

  Next, the inside of the autoclave is pressurized to a gauge pressure of 0.1 MPa, a pressing force is applied to the laminate A ′ via the pressing members 3a and 3b, and the inside of the autoclave is 130 ° C. at a temperature rising rate of 4 ° C./min. The laminated body A ′ is heated for 60 minutes so that the fiber reinforced plastic layer forming material becomes 130 ° C. (compression process), whereby the fiber reinforced plastic layer forming material 2 of the foam 1 ′ is heated. After crushing and flattening the bubbles contained in the surface portion on the surface where “is laminated, the epoxy resin in the fiber reinforced plastic layer forming material 2 ′ was cured to obtain the fiber reinforced plastic layer 2. After that, when the inside of the autoclave was cooled and the inside of the autoclave reached 60 ° C., the pressure inside the autoclave was released and the pressure was returned to the atmospheric pressure, the laminate A ′ was taken out, and the laminate A ′ was cooled to room temperature. Thereby, as shown in FIG. 1, the core foam layer 1a, the upper surface side surface foam layer 1b formed on the upper surface of the core foam layer 1a, and the lower surface side surface formed on the lower surface of the core foam layer 1a. A fiber reinforced composite A having a fiber reinforced plastic layer 2 formed by laminating and integrating the foam 1 including the foamed layer 1c and the upper surface side surface foamed layer 1b and the lower surface side surface foamed layer 1c was obtained. The laminated fiber reinforced plastic layer forming materials were integrated with the cured epoxy resin contained therein to form the fiber reinforced plastic layer 2. The excess epoxy resin in the fiber reinforcements 2 ′ and 2 ′ was absorbed by the breather cloth 6 through the through-holes and the outside of the release film 5 due to the pressure applied to the laminate A ′.

(Example 2)
Instead of foam containing acrylic resin A and having an unfoamed skin on the surface (foaming ratio 10 times, product name “Formac # 1000 grade” manufactured by Sekisui Plastics Co., Ltd.), acrylic resin A is included. In addition, a foam having an unfoamed skin on the surface (density 0.77 g / cm ³ , expansion ratio 15 times, product name “Formac # 1500 grade” manufactured by Sekisui Plastics Co., Ltd.) was used. In the same manner as in Example 1, a fiber reinforced composite A was obtained.

(Example 3)
Instead of a foam containing an acrylic resin A and having an unfoamed skin on the surface (expanding ratio 10 times, product name “Formac # 1000 grade” manufactured by Sekisui Plastics Co., Ltd.), an acrylic resin B is included. In addition, a foam having an unfoamed skin on the surface (a density of 0.76 g / cm ³ , a foaming magnification of 15 times, a product name “Heat Resistant Formac” manufactured by Sekisui Plastics Co., Ltd.) and a spacer thickness of 20.2 mm A fiber reinforced composite A was obtained in the same manner as in Example 1 except that the above was changed.

Example 4
The manufacturing apparatus shown in FIGS. 3 and 4 was used. First, 100 parts by weight of polyethylene terephthalate (PET, trade name “SA-135” manufactured by Mitsui Chemicals, glass transition temperature 78 ° C., melting point: 247.1 ° C.), master batch (polyethylene terephthalate) containing polyethylene terephthalate and talc. (Content: 60% by weight, talc content: 40% by weight) A polyethylene terephthalate composition containing 1.8 parts by weight and pyromellitic anhydride 0.2 parts by weight is a single piece having a diameter of 65 mm and an L / D ratio of 35. It supplied to the screw extruder and melt-kneaded at 290 degreeC.

  Subsequently, from the middle of the extruder, butane composed of 35% by weight of isobutane and 65% by weight of normal butane was pressed into the polyethylene terephthalate composition in a molten state so as to be 0.8 parts by weight with respect to 100 parts by weight of polyethylene terephthalate. And uniformly dispersed in polyethylene terephthalate.

  Then, after the polyethylene terephthalate composition in a molten state was cooled to 280 ° C. at the front end of the extruder, the polyethylene terephthalate composition was extruded and foamed from each nozzle of the multi-nozzle mold 10 attached to the front end of the extruder. .

  The multi-nozzle mold 10 has 20 nozzles having an outlet portion 11 having a diameter of 1 mm, and all the outlet portions 11 of the nozzle have a diameter of 139, which is assumed on the front end face 10a of the multi-nozzle die 10. It was arranged on a virtual circle C of 5 mm at regular intervals.

  Two rotary blades 50 are integrally provided on the outer peripheral surface of the rear end portion of the rotary shaft 20 with a phase difference of 180 ° in the circumferential direction of the rotary shaft 20, and each rotary blade 50 is a multi-nozzle. The mold 10 is configured to move on the virtual circle C while always in contact with the front end face 10a of the mold 10.

The cooling member 40 further includes a cooling drum 41 including a front circular front part 41a and a cylindrical peripheral wall part 41b extending rearward from the outer peripheral edge of the front part 41a and having an inner diameter of 320 mm. It was. The cooling water 42 at 20 ° C. was supplied into the cooling drum 41 through the supply pipe 41d and the supply port 41c of the cooling drum 41. The volume in the cooling drum 41 was 17684 cm ³ .

  The cooling water 42 is spirally drawn along the inner peripheral surface of the peripheral wall portion 41b of the cooling drum 41 by the centrifugal force accompanying the flow velocity when being supplied from the supply pipe 41d to the inner peripheral surface of the peripheral wall portion 41b of the cooling drum 41. The cooling liquid 42 gradually spreads in the direction perpendicular to the traveling direction while traveling along the inner peripheral surface of the peripheral wall portion 41b, and as a result, the supply port 41c of the cooling drum 41 The inner peripheral surface of the more peripheral wall portion 41b was in a state of being entirely covered with the coolant 42.

  Then, a polyethylene terephthalate extrudate extruded and foamed from the outlet portion 11 of each nozzle of the multi-nozzle mold 10 is rotated by a rotary blade 50 disposed on the front end face 10a of the multi-nozzle mold 10 at a rotational speed of 2500 rpm. Was cut with a rotary blade 50 to produce substantially spherical polyethylene terephthalate expanded particles. The polyethylene terephthalate extrudate consisted of an unfoamed portion immediately after being extruded from the nozzle of the multi-nozzle mold 10 and a foaming portion in the process of foaming continuous with the unfoamed portion. The polyethylene terephthalate extrudate was cut at the open end of the outlet portion 11 of the nozzle, and the cut surface of the polyethylene terephthalate extrudate was formed at the unfoamed portion.

  In the production of the above-mentioned polyethylene terephthalate foamed particles for in-mold foam molding, first, the rotating shaft 20 was not attached to the multi-nozzle mold 10 and the cooling member 40 was retracted from the multi-nozzle mold 10. In this state, the polyethylene terephthalate extrudate is extruded and foamed from the extruder, and the polyethylene terephthalate extrudate immediately after being extruded from the nozzle of the multi-nozzle mold 10 and in the process of foaming continuous to the unfoamed portion. It confirmed that it consisted of a foaming part. Next, after attaching the rotating shaft 20 to the multi-nozzle mold 10 and disposing the cooling member 40 at a predetermined position, the rotating shaft 20 is rotated, and the polyethylene terephthalate extrudate is rotated at the opening end of the outlet portion 11 of the nozzle. Cutting with 50 produced polyethylene terephthalate expanded particles.

  The polyethylene terephthalate expanded particles are blown outward or forward by the cutting stress of the rotary blade 50, and the flow of the cooling water 42 flows into the cooling water 42 flowing along the inner surface of the cooling drum 41 of the cooling member 40. The polyethylene terephthalate foamed particles entered the cooling water 42 and immediately cooled as they collided with the surface of the cooling water 42 so as to follow the cooling water 42 from the upstream side to the downstream side.

  The cooled polyethylene terephthalate expanded particles were discharged together with the cooling water 42 through the discharge port 41e of the cooling drum 41, and then separated from the cooling water 42 by a dehydrator.

The polyethylene terephthalate expanded particles had an open cell ratio of 2%, a bulk density of 0.5 g / cm ³ , and a crystallinity of 5%. The butane content in the polyethylene terephthalate expanded particles was 0.5 parts by weight with respect to 100 parts by weight of polyethylene terephthalate.

  An in-mold foam molding machine equipped with molds (male mold and female mold) was prepared. In a state where the male mold and the female mold are clamped, a rectangular parallelepiped cavity having an internal dimension of 30 mm in length, 300 mm in width, and 300 mm in height is formed between the male and male molds.

  The mold cavity was filled with polyethylene terephthalate foam particles in the mold cavity of the in-mold foam molding machine. Thereafter, 105 ° C. water vapor is supplied into the mold cavity at a gauge pressure of 0.13 MPa for 90 seconds to cause secondary foaming of the polyethylene terephthalate foamed particles and secondary foaming of the polyethylene terephthalate foamed particles. The obtained secondary foamed particles were heat-fused and integrated with each other by these foaming pressures to obtain a rectangular solid-shaped foamed molded product having a length of 30 mm × width of 300 mm × height of 300 mm.

  Next, cooling water was supplied into the mold cavity to cool the foam molded article, and then the cavity was opened to obtain a foam molded article. The obtained foamed molded product was allowed to stand (cured) at 60 ° C. for 168 hours under atmospheric pressure to obtain a foam (foaming ratio 6 times). An unfoamed skin was formed on the surface of the foam.

  Instead of a foam containing an acrylic resin A and having an unfoamed skin on the surface (foaming ratio 10 times, product name “Formac # 1000 grade” manufactured by Sekisui Plastics Co., Ltd.), it was produced as described above. A fiber-reinforced composite A was obtained in the same manner as in Example 1 except that the foam was used and the thickness of the spacer was changed to 17.2 mm.

(Example 5)
The internal dimensions between the male and female dies were 20 mm long x 300 mm wide x 300 mm high, and a rectangular shaped foam molded body of 20 mm long x 300 mm wide x 300 mm high was obtained in the same manner as in Example 4, A foam having an unfoamed skin formed on the surface (foaming ratio 6 times) was produced. Then, instead of the foam containing the acrylic resin A and having an unfoamed skin on the surface (foaming ratio 10 times, product name “Formac # 1000 grade” manufactured by Sekisui Plastics Co., Ltd.), as described above A fiber-reinforced composite A was obtained in the same manner as in Example 1 except that the produced foam was not cut and removed, and the thickness of the spacer was changed to 17.2 mm.

(Example 6)
In the same way as in Example 4 except that butane was pressed into the molten polyethylene terephthalate composition so as to be 1.0 part by weight with respect to 100 parts by weight of polyethylene terephthalate from the middle of the extruder, it was not foamed on the surface. A foam (10 times the expansion ratio) was obtained. Then, instead of the foam containing the acrylic resin A and having an unfoamed skin on the surface (foaming ratio 10 times, product name “Formac # 1000 grade” manufactured by Sekisui Plastics Co., Ltd.), as described above A fiber-reinforced composite A was obtained in the same manner as in Example 1 except that the produced foam was not cut and removed, and the thickness of the spacer was changed to 14.2 mm.

(Example 7)
The internal dimensions between the male and female dies were 20 mm long x 300 mm wide x 300 mm high, and a rectangular shaped foam molded body of 20 mm long x 300 mm wide x 300 mm high was obtained in the same manner as in Example 4, A foam having an unfoamed skin formed on the surface (foaming ratio 6 times) was produced. The foam was used without cutting off the epidermis.

Fiber reinforcement with a thickness of 0.23 mm containing 40% by weight of an uncured epoxy resin (glass transition temperature: 121 ° C.) as a thermosetting resin in a reinforcing fiber substrate formed of a twill weave made of carbon fiber Two plastic layer forming materials (trade name “Pyrofil Prepreg TR3523-395GMP” manufactured by Mitsubishi Rayon Co., Ltd., basis weight: 200 g / m ² ) were prepared. The fiber reinforced plastic layer forming material was a square shape with a side of 300 mm. Two fiber-reinforced plastic layer forming materials were superposed so that their warp length directions were at an angle of 90 ° to each other. Further, two identical fiber reinforced plastic layer forming materials were prepared, and the two fiber reinforced plastic layer forming materials were overlapped so that the length directions of their warps formed an angle of 90 ° with each other.

  A laminate was prepared by laminating two superposed fiber reinforced plastic layer forming materials on both surfaces of the foam.

  A pair of molds was prepared. In a state in which the pair of molds are clamped, a rectangular parallelepiped cavity having a length of 300 mm × width of 300 mm × height of 17.2 mm is formed between the pair of molds. In order to easily take out the fiber-reinforced composite from the mold, a mold release treatment was performed on the entire inner surface of the mold cavity in the same manner as in Example 1.

  After the cavities of the pair of molds were opened and the laminate was disposed in the cavity, the pair of molds were clamped to close the cavities. Next, the mold temperature was heated to 140 ° C., and the laminate housed in the cavities of the pair of molds was heated for 1 minute so that the fiber-reinforced plastic layer forming material was 140 ° C. . By heating the laminate, the bubbles contained in the surface portion on the surface on which the foam fiber reinforced plastic layer forming material was laminated were crushed and flattened.

  Further, in a state where the mold is clamped, the mold temperature is increased to 145 ° C. at a temperature increase rate of 1 ° C./min, so that the fiber reinforced plastic layer forming material becomes 145 ° C. The mixture was heated for 5 minutes to cure the epoxy resin in the fiber reinforced plastic layer forming material, and the fiber reinforced plastic layer forming material was laminated and integrated on the surface of the foam to obtain a fiber reinforced composite. The fiber reinforced plastic layer forming materials were also integrated by the cured epoxy resin contained therein. The fiber reinforced composite was cooled and a pair of molds were opened to obtain a fiber reinforced composite. The resulting fiber-reinforced composite is made of a fiber-reinforced plastic layer in which the reinforcing fibers are bonded and fixed together by a cured epoxy resin, and the cured epoxy resin is used on both sides of the foam along the surfaces thereof. It was laminated and integrated in close contact.

(Example 8)
A foam containing an acrylic resin A and having an unfoamed skin on the surface (density 0.77 g / cm ³ , expansion ratio 15 times, product name “Formac # 1500 grade” manufactured by Sekisui Plastics Co., Ltd.) Prepared as an anti-foam. The skin was cut off from the foam to expose the cell cross section on the surface of the foam. The foam after the skin was cut and removed had a planar square shape with a side of 300 mm and a thickness of 20 mm.

Fiber reinforced plastic in which 40% by weight of a thermoplastic epoxy resin (glass transition temperature: 97 ° C.) is impregnated into a reinforced fiber base material formed from a satin weave fabric made of glass fiber (trade name “WE181D” manufactured by Nitto Boseki Co., Ltd.) Two layer forming materials (trade name “NNGF60-03s” manufactured by Nagase Chemtech Co., Ltd., basis weight: 300 g / m ² , thickness: 0.3 mm) were prepared. The fiber reinforced plastic layer forming material was a square shape with a side of 300 mm. Two fiber-reinforced plastic layer forming materials were superposed so that their warp length directions were at an angle of 90 ° to each other. Further, two identical fiber reinforced plastic layer forming materials were prepared, and the two fiber reinforced plastic layer forming materials were overlapped so that the length directions of their warps formed an angle of 90 ° with each other.

  A laminate was prepared by laminating two superposed fiber reinforced plastic layer forming materials on both surfaces of the foam.

  A pair of molds was prepared. In a state where the pair of molds are clamped, a rectangular parallelepiped cavity having a length of 300 mm × width of 300 mm × height of 18.2 mm is formed between the pair of molds. In order to easily take out the fiber-reinforced composite from the mold, a mold release treatment was performed on the entire inner surface of the mold cavity in the same manner as in Example 1.

  After the cavities of the pair of molds were opened and the laminate was disposed in the cavity, the pair of molds were clamped to close the cavities. Next, the mold temperature was heated to 125 ° C., and the laminate housed in the cavities of the pair of molds was heated for 1 minute so that the fiber-reinforced plastic layer forming material was 125 ° C. . By heating the laminate, the bubbles contained in the surface portion on the surface on which the foam fiber reinforced plastic layer forming material was laminated were crushed and flattened.

  Further, in a state where the mold is clamped, the mold temperature is increased to 130 ° C. at a temperature increase rate of 1 ° C./min so that the laminated body has a fiber reinforced plastic layer forming material of 130 ° C. After heating for 5 minutes, the laminate was cooled to 30 ° C. or less, and the fiber reinforced plastic layer forming material was laminated and integrated with the surface of the foam to obtain a fiber reinforced composite. The fiber reinforced plastic layer forming materials were also integrated by the cured epoxy resin contained therein. The fiber reinforced composite was cooled and a pair of molds were opened to obtain a fiber reinforced composite. The obtained fiber reinforced composite is a fiber reinforced plastic layer in which the reinforcing fibers are bound and fixed by the thermoplastic epoxy resin, and the thermoplastic epoxy resin is used to completely cover the both sides of the foam along their surfaces. It was laminated and integrated in close contact.

Example 9
A foam was produced in the same manner as in Example 7, and this foam was used. The same as Example 8 except that the height of the cavity formed between the pair of molds was 17.2 mm. Thus, a fiber reinforced composite was obtained.

(Comparative Example 1)
A fiber-reinforced composite A was obtained in the same manner as in Example 1 except that the thickness of the spacers 4a and 4b was changed to 11.2 mm.

(Comparative Example 2)
A fiber-reinforced composite A was obtained in the same manner as in Example 1 except that the spacers 4a and 4b were not placed on the outer sides of both end portions in the width direction of the laminate A ′.

(Comparative Example 3)
A fiber-reinforced composite A was obtained in the same manner as in Example 1 except that the thickness of the spacers 4a and 4b was changed to 21.2 mm.

(Comparative Example 4)
A fiber-reinforced composite A was obtained in the same manner as in Example 5 except that the thickness of the spacers 4a and 4b was changed to 21.2 mm.

(Comparative Example 5)
A fiber-reinforced composite A was obtained in the same manner as in Example 6 except that the thickness of the spacers 4a and 4b was changed to 21.2 mm.

(Comparative Example 6)
A fiber-reinforced composite was obtained in the same manner as in Example 8 except that the height of the cavity formed between the pair of molds was 11.2 mm.

(Evaluation)
For each of the core foam layer, the upper surface side foam layer and the lower surface foam layer constituting the foam contained in the fiber reinforced composite, the average aspect ratio of the bubbles, the average major axis of the bubbles, the apparent density, and The durometer hardness was measured according to the procedure described above. Moreover, the compression deformation rate of the foam in the compression process was measured according to the above-described procedure. Furthermore, the specific absorbed energy amount of the fiber reinforced composite A was evaluated according to the procedure described above. These results are shown in Tables 1 and 2.

A Fiber reinforced composite
1a Core foam layer
1b Surface layer (surface foam layer)
1c Surface layer (surface foam layer)
1 Foam 2 Fiber reinforced plastic layer
3a Pressing member
3b Press member
4a Spacer 5 Release film 6 Breather cross 7 Bagging film 8 Sealing material 9 Back valve B Space
10 nozzle mold
11 Exit
20 axis of rotation
30 Drive member
40 Cooling member
41 Cooling drum
42 Coolant C Virtual circle
50 rotary blade

Claims (5)

A fiber reinforced composite having a foam including a core foam layer and a surface layer formed on both surfaces of the core foam layer, and a fiber reinforced plastic layer laminated and integrated on at least one of the surface layers. And
The surface layer in which the fiber reinforced plastic layer is laminated and integrated among the surface layers is formed as a harder surface foam layer than the core foam layer,
The average aspect ratio (Ac) of the bubbles contained in the core foam layer is 0.65 to 1, and the average aspect ratio (As) of the bubbles contained in the surface foam layer is 0.5 to 1. A fiber-reinforced composite characterized by being 0.8.   The fiber reinforcement according to claim 1, wherein an average aspect ratio (Ac) of bubbles contained in the core foam layer is larger than an average aspect ratio (As) of bubbles contained in the surface foam layer. Complex.   The difference (Ac−As) of the average aspect ratio (As) of the bubbles contained in the surface foam layer with respect to the average aspect ratio (Ac) of the bubbles contained in the core foam layer is 0.14 or more. The fiber-reinforced composite according to claim 1 or 2, characterized by the above.   The laminated body in which the fiber reinforced plastic layer forming material containing the reinforcing fiber impregnated with the reinforcing synthetic resin is laminated on at least one surface of the foam is a temperature lower by 50 ° C. than the glass transition temperature of the reinforcing synthetic resin. It has the compression process which compresses so that the compression deformation rate of the above-mentioned foam may be 1 to 45%, while heating at the temperature below 60 ° C higher than the glass transition temperature of the above-mentioned synthetic resin for reinforcement. A method for producing a fiber-reinforced composite.   Prior to the compression step, the laminate has a preheating step of heating the laminate at a temperature that is 120 ° C. lower than the glass transition temperature of the reinforcing synthetic resin and less than 80 ° C. higher than the glass transition temperature of the reinforcing synthetic resin. The method for producing a fiber-reinforced composite according to claim 4.

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