JP6404197B2 - FIBER-REINFORCED FOAM, PROCESS FOR PRODUCING THE SAME, AND FIBER-REINFORCED COMPOSITE USING FIBER-REINFORCED FOAM - Google Patents

Description

  The present invention relates to a fiber reinforced foam, a method for producing the same, and a fiber reinforced composite having the fiber reinforced foam as a core material.

In recent years, fiber-reinforced synthetic resins reinforced with fibers are lightweight and have high mechanical strength, so demand is high in fields where high mechanical strength and light weight are required, such as in the automotive field, ship field, and aircraft field. Is expanding.
Among the fields of automobiles, ships, aircrafts, etc., particularly in the automobile field, it is strongly required that the structural members are lightweight and have high strength.
In order to satisfy the above requirements, a fiber reinforced composite has been proposed in which a resin foam such as a foam or a bead foam molded body is used as a core material, and a fiber reinforced resin material is laminated and integrated on the surface of the core material. Yes.
In this fiber reinforced composite, a fiber reinforced resin layer with excellent strength is formed on the surface layer portion by the fiber reinforced resin material and an excellent lightness is exhibited by the core material. Therefore, the roof, bonnet, fender of an automobile It is said to be useful as a member such as an undercover and a trunk lid.

  Regarding such a fiber-reinforced composite, JP-A-2015-017190 (Patent Document 1) describes a composite molded body composed of a plurality of resin foam pieces and a cured product of a thermosetting resin. In this composite molded body, a cured product is formed by impregnating and curing a thermosetting resin raw material between resin foam small pieces. Moreover, the hardened | cured material which comprises a composite molded object occupies 3-30 volume%.

Japanese Patent Laying-Open No. 2015-017190

  Since the composite molded body of Patent Document 1 is configured to exhibit strength with a thermosetting resin, the strength and rigidity per weight unit are insufficient.

The present inventors diligently studied a member that exhibits a sufficient improvement effect based on the above-described knowledge that the thermosetting resin has an insufficient effect of improving the strength and rigidity per weight unit. As a result, it has been found that the strength and rigidity per unit of weight can be greatly improved if reinforcing fibers are present together with the binder resin in the foam instead of the thermosetting resin, and the present invention has been completed.
Thus, according to the present invention, a fiber reinforced foam including a thermoplastic resin foam, a binder resin, and reinforcing fibers, wherein the fiber reinforced foam includes 1 to 40% by volume of the reinforcing fibers, and the reinforcing fibers are Present at least partially in the binder resin ,
The thermoplastic foam is a fusion product of a plurality of foam particles,
The binder resin and the reinforcing fiber are derived from a fiber reinforced resin containing a binder resin and a reinforcing fiber, and the reinforcing fiber is a face material selected from a sheet-like material composed of a woven fabric, a nonwoven fabric, and a fiber bundle, fiber reinforced foam surface material is characterized Rukoto which have a surface area of up to face the 0.01～100Mm ² is provided.

Moreover, according to this invention, the fiber reinforced composite_body | complex characterized by making the said fiber reinforced foam into a core material is provided.
Furthermore, according to the present invention, there is provided a method for producing the above fiber-reinforced foam,
When the thermoplastic resin foam is obtained by molding, and the binder resin is a thermosetting resin, the binder resin is obtained by thermosetting from a thermosetting resin simultaneously with the molding. A method of manufacturing a body is provided.

ADVANTAGE OF THE INVENTION According to this invention, the fiber reinforced foam which has the outstanding mechanical strength, its manufacturing method, and a fiber reinforced composite can be provided.
In any of the following cases, a fiber-reinforced foam having superior mechanical strength can be provided.
(1) The thermoplastic foam is a fusion product of a plurality of foam particles.
(2) The reinforcing fibers are long fibers having a fiber length of 1 mm or more, the foamed particles have a non-foamed layer on the surface, and the long fibers are present on the non-foamed layer.
(3) The reinforcing fiber includes at least a part of long fibers in contact with three or more foamed particles.
(4) The reinforcing fiber is made of carbon fiber or glass fiber.
(5) The binder resin and the reinforcing fiber are derived from a fiber reinforced resin including the binder resin and the reinforcing fiber, and the reinforcing fiber is a face material selected from a sheet-like material including a woven fabric, a nonwoven fabric, and a fiber bundle, face material has a surface area of up to face the 0.01~100mm ^2.

  Further, in the method for producing a fiber reinforced foam, a thermoplastic resin foam is obtained by molding foamed particles, and is a face material selected from a sheet-like material composed of a woven fabric, a nonwoven fabric, and a fiber bundle in a binder resin. When reinforced fibers are included, a fiber reinforced foam having better mechanical strength can be produced.

It is the schematic of the fiber reinforced foam of this invention. It is the schematic of the fiber reinforced foam of this invention. 2 is a cross-sectional photograph of the fiber-reinforced foam of Example 1.

(Fiber reinforced foam)
The fiber reinforced foam includes a thermoplastic resin foam, a binder resin, and reinforcing fibers. In the case of a thermosetting resin, the binder resin means a resin obtained by thermosetting. On the other hand, in the case of a thermoplastic resin, foaming in a foam obtained by foaming foamed particles by foaming the foamed particles by being in a molten state when foamed particles are foamed during in-mold foam molding It means a resin capable of bonding and integrating particles and reinforcing fibers.
(1) Thermoplastic resin foam (a) Thermoplastic resin The thermoplastic resin constituting the thermoplastic foam includes polyester resin, polycarbonate resin, acrylic resin, polyphenylene ether resin, polymethacrylimide resin, and polyolefin resin. , Polystyrene resin, polyamide resin and the like.
As the polyester resin, a linear polyester obtained by condensation polymerization of a dicarboxylic acid and a dihydric alcohol can be generally used. The thermoplastic resin may consist of one or more resins.
Examples of the thermoplastic polyester resin include an aromatic polyester resin and an aliphatic polyester resin.

  The aromatic polyester resin is a polyester containing an aromatic dicarboxylic acid component and a diol component. Examples of this resin include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polycyclohexanedimethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, and the like. Of these, polyethylene terephthalate is preferred.

In addition to the aromatic dicarboxylic acid component and the diol component, the aromatic polyester resin may be, for example, a tricarboxylic acid such as trimellitic acid or a trivalent or higher polyvalent carboxylic acid such as tetracarboxylic acid such as pyromellitic acid. The anhydride, a triol such as glycerin, and a trihydric or higher polyhydric alcohol (for example, a tetraol such as pentaerythritol) may be contained as a constituent component.
As the aromatic polyester resin, a recycled material collected and regenerated from a used PET bottle or the like can be used.

  Polyethylene terephthalate may be crosslinked by a crosslinking agent. A well-known thing is used as a crosslinking agent. Examples of the crosslinking agent include acid dianhydrides such as pyromellitic anhydride, polyfunctional epoxy compounds, oxazoline compounds, and oxazine compounds. In addition, you may use together a crosslinking agent 1 type (s) or 2 or more types.

  When polyethylene terephthalate is crosslinked with a crosslinking agent, the crosslinking agent may be supplied to the extruder together with the polyethylene terephthalate. 0.01-5 mass parts is preferable with respect to 100 mass parts of polyethylene terephthalates, and, as for the quantity of the crosslinking agent supplied to an extruder, 0.1-1 mass part is more preferable. If the amount of the crosslinking agent is too small, the melt viscosity at the time of melting of polyethylene terephthalate becomes too small, and bubbles may be broken. If the amount is too large, the melt viscosity of polyethylene terephthalate at the time of melting becomes too high, and extrusion foaming may be difficult when the foam is produced by extrusion foaming.

Examples of the aliphatic polyester resin include a polylactic acid resin.
As the polylactic acid resin, a resin in which lactic acid is polymerized by an ester bond can be used. A polylactic acid resin is a copolymer of D-lactic acid (D-form) and L-lactic acid (L-form), D-lactic acid or L-, from the viewpoint of commercial availability and imparting foamability to foamed particles. A ring-opening polymer of one or more lactides selected from the group consisting of any one homopolymer of lactic acid, D-lactide, L-lactide and DL-lactide is preferred. In addition, you may use together 1 type (s) or 2 or more types of polylactic acid-type resin.

  Polylactic acid-based resins include, as monomer components other than lactic acid, for example, aliphatic hydroxycarboxylic acids such as glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid, hydroxyheptanoic acid; succinic acid, adipic acid, suberic acid, sebacin Aliphatic polycarboxylic acids such as acid, dodecanedicarboxylic acid, succinic anhydride, adipic anhydride, trimesic acid, propanetricarboxylic acid, pyromellitic acid, pyromellitic anhydride; ethylene glycol, 1,4-butanediol, 1, It may contain aliphatic polyhydric alcohols such as 6-hexanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, decamethylene glycol, glycerin, trimethylolpropane and pentaerythritol.

  The polylactic acid resin may contain other functional groups such as an alkyl group, a vinyl group, a carbonyl group, an aromatic group, an ester group, an ether group, an aldehyde group, an amino group, a nitrile group, and a nitro group. The polylactic acid-based resin may be crosslinked by an isocyanate-based crosslinking agent or the like, or may be bound by a bond other than an ester bond.

The acrylic resin is produced by polymerizing a (meth) acrylic monomer. In addition, (meth) acryl means acryl or methacryl.
The (meth) acrylic monomer is not particularly limited, and (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, lauryl (meth) acrylate, (meth ) 2-ethylhexyl acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, (meth) acrylamide and the like.
Moreover, acrylic resin may contain the monomer component copolymerizable with this other than the said (meth) acrylic-type monomer. Examples of such monomers include maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, crotonic acid, maleic amide, maleic imide and the like.

The polystyrene resin is not particularly limited. For example, a homopolymer or copolymer of a styrene monomer such as styrene, methylstyrene, ethylstyrene, i-propylstyrene, dimethylstyrene, chlorostyrene, bromostyrene, styrene Examples thereof include a copolymer of a monomer and one or more vinyl monomers copolymerizable with the styrenic monomer.
The thermoplastic resin is preferably a polyester resin, an acrylic resin, or the like that is excellent in affinity with the thermosetting resin.

(B) Foamed particles The thermoplastic resin foam is preferably a fusion product of a plurality of foamed particles. The shape of the expanded particles is not particularly limited. For example, spherical shape, cylindrical shape, etc. are mentioned. Of these, it is preferable that the shape be as spherical as possible. The expanded particles preferably have an average particle diameter of 0.5 to 5 mm.
The foamed particles preferably have a non-foamed layer on the surface. Not only the expanded particles are firmly fused by the non-foamed layer, but also deformation of the fiber-reinforced foam under load can be suppressed.

The average thickness of the non-foamed layer is preferably 0.005 to 1.0 mm, and more preferably 0.01 to 0.8 mm. If the average thickness of the non-foamed layer is too thin, the effect of suppressing deformation under load is reduced, and the mechanical strength of the fiber-reinforced foam may be lowered. If it is too thick, the fiber-reinforced foam may become too hard and brittle, and the weight may increase and the lightness may be lost.
In addition, the thickness of a non-foaming layer means the thickness of the direction orthogonal to the surface of a non-foaming layer. The average thickness of the non-foamed layer refers to the average value of the minimum thickness and the maximum thickness of the non-foamed layer.
The expanded particles can be produced by the following method.
(I) Supplying the resin into the extruder, melt-kneading in the presence of a physical foaming agent, cutting the resin extrudate from the nozzle mold attached to the extruder while extrusion foaming, and cooling to produce expanded particles how to.
(Ii) A resin is supplied into an extruder, melted and kneaded in the presence of a physical foaming agent, and extruded and foamed from a nozzle mold attached to the extruder to produce a strand-like resin extrudate. A method for producing foamed particles by cutting at predetermined intervals.
(Iii) Supplying resin into the extruder, melt-kneading in the presence of a physical foaming agent, extrusion-foaming from an annular die or T-die attached to the extruder to produce a foam, and cutting the foam To produce expanded particles.
(Iv) After producing thermoplastic resin particles by suspension polymerization and impregnating a foaming agent with an autoclave to produce expandable particles, the mixture is heated and foamed using a pre-foaming machine capable of supplying a heat medium such as water vapor. A method for producing expanded particles.
(V) A thermoplastic resin is supplied into an extruder, melt-kneaded and extruded from a nozzle die attached to the extruder to produce a strand-like extrudate, and the extrudate is cut at predetermined intervals to obtain resin particles. Is produced by impregnating a foaming agent with an autoclave to produce expandable particles, and then heated and foamed using a pre-foaming machine capable of supplying a heat medium such as water vapor.

  Examples of the physical blowing agent include saturated aliphatic hydrocarbons such as propane, normal butane, isobutane, normal pentane, isopentane and hexane, ethers such as dimethyl ether, methyl chloride, halogenated hydrocarbons, carbon dioxide and nitrogen. . Among these, dimethyl ether, propane, normal butane, isobutane and carbon dioxide are preferable, propane, normal butane and isobutane are more preferable, and normal butane and isobutane are particularly preferable. The physical foaming agent may be used alone or in combination of two or more.

(2) Binder resin The binder resin is derived from one that is adhered to the surface of the reinforcing fiber prior to the production of the foam by molding, or one that is dry blended with the reinforcing fiber and the expanded particles. The resin constituting this binder resin is a thermoplastic obtained by foaming foamed particles by foaming the foamed particles when they are foamed in-mold and in a molten state when they are foamed. There is no particular limitation as long as the foam particles and the reinforcing fibers constituting the resin foam can be bonded and integrated. A thermoplastic resin and a thermosetting resin can be used as the binder resin.
(A) Thermoplastic resin Examples of the thermoplastic resin include low-density polyethylene, polyvinyl acetate, thermoplastic polyester resin, polyamide resin, ionomer resin, and polyurethane resin. Among these, a thermoplastic polyester resin is preferable, and a crystalline thermoplastic polyester resin is more preferable from the viewpoint of improving the mechanical strength of the foamed molded article by crystallization of the adhesive resin. Specifically, as the thermoplastic polyester resin, for example, terephthalic acid commercially available from DIC under the trade name “M8843” is used as the main dicarboxylic acid component, and neopentyl glycol is used as the main glycol component. Thermoplastic polyester resin (glass transition temperature: 65.9 ° C), terephthalic acid and adipic acid commercially available from Tokyo Ink as trade name “G-125” are the main dicarboxylic acid components, and ethylene glycol is the main glycol. Examples thereof include crystalline thermoplastic polyester resins (melting point: 100.6 ° C., glass transition temperature: 8.3 ° C.) as components.
(B) Thermosetting resin The thermosetting resin is not particularly limited. For example, epoxy resin, unsaturated polyester resin, phenol resin, melamine resin, polyurethane resin, silicone resin, maleimide resin, vinyl ester resin, cyanate ester resin. And a resin derived from a thermosetting resin obtained by polymerizing a maleimide resin and a cyanate ester resin. Of these, epoxy resins and vinyl ester resins are preferred because of their excellent heat resistance, shock absorption or chemical resistance.

As an epoxy resin, it is a polymer or copolymer of epoxy compounds and has a linear structure, or a copolymer of an epoxy compound and a monomer that can be polymerized with this epoxy compound, and has a linear structure. And a copolymer having.
Specifically, as the 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 epoxy resin , Glycidyl ester type epoxy resin, glycidyl amine type epoxy resin and the like. Among these, bisphenol A type epoxy resins and bisphenol fluorene type epoxy resins are preferable. In addition, you may use together 1 type, or 2 or more types of epoxy resins.

(3) Reinforcing fibers Reinforcing fibers include glass fibers, carbon fibers, silicon carbide fibers, alumina fibers, Tyranno fibers, basalt fibers, ceramic fibers, etc .; metal fibers such as stainless steel fibers and steel fibers; aramid fibers, polyethylene Examples thereof include organic fibers such as fibers and polyparaphenylene benzoxador (PBO) fibers; boron fibers and the like.
One or more reinforcing fibers may be used in combination.
Among these, carbon fiber, glass fiber, and aramid fiber are preferable, and carbon fiber and glass fiber are more preferable. These reinforcing fibers have excellent mechanical properties despite being lightweight.
The fiber length of the reinforcing fiber is preferably 1 mm or more, more preferably 1 to 30 mm, and particularly preferably 1 to 10 mm. If the fiber length is too short, strength may not be exhibited. If the fiber is too long, not only the filling property of the foamed particles is deteriorated during the production of the foam, but also there is a possibility that the in-plane strength variation becomes large.

The binder resin between the expanded particles preferably has the same composition and configuration as the above-described fiber reinforced layer. The amount of the binder resin contained in the fiber reinforced foam is preferably 1 to 40% by weight, more preferably 2 to 35% by weight, and particularly preferably 3 to 30% by weight. When the amount of the resin is small, the adhesion between the fiber and the foam is lowered, and when the fiber-reinforced composite is obtained, the strength may be low. If the amount of resin is large, the effect of reducing the weight may be reduced. Regarding the dispersibility of the fibers, it is preferable that the amount of fibers near the surface is large. Even if it is uniform, there is no problem, but the presence of a large amount in the vicinity of the surface has a high effect of improving the strength.
Moreover, it is preferable that a reinforced fiber contains at least one part of the long fiber which contact | connects 3 or more of foamed particles. When the number is three or more, the apparent fusion strength between the expanded particles is improved, and the strength is effectively improved.
Note that recycled materials can be used for the reinforcing fibers. The recycled material refers to a discarded part other than a part used as a product in a prepreg or the like.

A method for observing reinforcing fibers without limitation is shown below.
First, the fiber reinforced composite is cut along a plane orthogonal to the surface, and the cut surface is enlarged 100 to 200 times using an electron microscope to obtain an enlarged photograph. In addition, as an electron microscope, the electron microscope marketed with the brand name "digital microscope VHX-1000" from Keyence Corporation can be used, for example.
The determination of each region (presence / absence of thermosetting resin) can be made based on microscopic FT-IR measurement inside and outside the region identified by the microscope. For epoxy resins, for example, 3100 cm ^-1, absorption peaks were observed at around 3600 cm ^-1, it can be determined.
The amount of reinforcing fiber in the fiber-reinforced foam is preferably 1 to 40% by weight, more preferably 1 to 30% by weight, and particularly preferably 3 to 30% by weight. If it is this range, it will become a structure with a good balance of intensity | strength, the addition amount of a fiber, and weight. The determination as to whether the resin is a semi-curable resin can be determined by having an exothermic peak in calorimetric measurement such as DSC.

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, non-woven fabrics, and face materials obtained by binding (stitching) 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 binding yarn include synthetic resin yarns such as polyamide resin yarns and polyester resin yarns, and stitch yarns such as glass fiber yarns.

The reinforcing fiber substrate may be used without laminating only one reinforcing fiber substrate, or a plurality of reinforcing fiber substrates may be laminated and used as a laminated reinforcing fiber substrate.
Examples of the laminated reinforcing fiber base material obtained by laminating a plurality of reinforcing fiber base materials include the following modes.
(I) A laminated reinforcing fiber base material prepared by laminating only one kind of reinforcing fiber base material and laminating these reinforcing fiber base materials.
(Ii) A laminated reinforcing fiber substrate in which a plurality of types of reinforcing fiber substrates are prepared and these reinforcing fiber substrates are laminated.
(Iii) preparing a plurality of reinforcing fiber bases obtained by binding (sewing) fiber bundles (strands) obtained by aligning reinforcing fibers in one direction with yarns. A laminated reinforcing fiber base material formed by superimposing them so as to be directed in different directions and integrating (stitching) the superposed reinforcing fiber base materials with a thread.

The reinforcing fiber is preferably present in the fiber-reinforced foam as a fiber-reinforced resin containing a binder resin and a reinforcing fiber. The fiber reinforced resin is preferably obtained by impregnating a binder fiber with a reinforcing fiber and curing it.
The fiber reinforced resin sheet may contain a curing agent or curing accelerator for curing the thermosetting resin, or may contain other additives. The thermosetting resin may be used alone or in combination of two or more.
The content of the binder resin in the fiber reinforced resin is preferably 20 to 70% by mass, and more preferably 30 to 60% by mass. If the resin content is too small, the binding property between the reinforcing fibers becomes insufficient, and the mechanical properties of the fiber-reinforced foam may not be sufficiently improved. Moreover, when there is too much content of resin, a mechanical physical property may fall.

The fiber reinforced resin is preferably a face material, and the thickness is preferably 0.01 to 2 mm, and more preferably 0.02 to 1 mm. According to the face material having a thickness within this range, it is possible to provide a fiber-reinforced foam excellent in mechanical properties despite being lightweight.
The face material preferably has a maximum surface area of 0.01 to 100 mm ² . According to the face material having an area in this range, a fiber-reinforced foam having excellent mechanical properties can be provided.
Basis weight of the fiber-reinforced resin is preferably ^{50~4000g / m 2, 100~1000g / m} 2 is more preferable. A fiber reinforced resin having a basis weight within this range is excellent in mechanical properties despite being lightweight.

A known method can be used as thermoforming for imparting a three-dimensional shape such as a raised portion to a preform formed by laminating a fiber reinforced resin material on a core material.
Examples of thermoforming include vacuum forming, pressure forming, and compression forming.
Examples of thermoforming methods that apply vacuum forming, pressure forming, and compression forming include straight forming, drape forming, plug assist forming, plug assist reverse draw forming, air slip forming, and snapback. Examples thereof include a molding method, a reverse draw molding method, a plug assist / air slip molding method, a match molding method, a press molding method, an SMC molding method, and a thermoforming method combining these molding methods. Among these, a fiber reinforced composite having a good appearance can be obtained even if a fiber reinforced resin material having poor moldability is used, and therefore, a press molding method and a match mold molding method are preferable.

(4) Density of structure fiber-reinforced foams of the fiber-reinforced foam, preferably ^{0.05~1.2g / cm 3, 0.08~0.9g / cm} 3 is more preferable. If the density is too low, the mechanical strength of the fiber-reinforced foam may be lowered. If it is too high, it may be difficult to maintain the shape of the fiber-reinforced foam.
The thickness is preferably 1 to 30 mm, and particularly preferably 1 to 10 mm.
A schematic diagram of the preferred structure of the fiber reinforced foam is shown in FIGS. In these drawings, the thermoplastic resin foam is a fusion product of a plurality of foam particles, and reinforcing fibers are located between the foam particles. Moreover, the thermosetting resin covers the reinforcing fibers located between the foamed particles, and plays a role of holding the reinforcing fibers in the fiber-reinforced foam. FIG. 1 shows a case where the reinforcing fiber is a short fiber, and FIG. 2 shows a case where the reinforcing fiber is a long fiber. 1 and 2, 1 is foamed particles, 2 is a thermosetting resin, 3 is short fibers, and 4 is long fibers.

(Method for producing fiber-reinforced foam)
When the thermoplastic resin foam is obtained by molding, the fiber reinforced foam using the thermosetting resin as a binder resin can be obtained by thermosetting the thermosetting resin from the thermosetting resin simultaneously with the molding. A fiber reinforced foam using a thermoplastic resin as a binder resin can be obtained by softening the thermoplastic resin simultaneously with molding and solidifying after molding.
A thermoplastic resin foam is obtained by molding foamed particles, and the binder resin contains reinforcing fibers that are face materials (woven fabric, non-woven fabric, or sheet-like material composed of fiber bundles), and is easy to manufacture From the viewpoint of Specifically, the foam particles are filled in a mold, and the foam particles are heated and foamed by heat transfer from a mold using a heat medium such as hot water or steam and a heater heat source, and the foam pressure of the foam particles There is a method (in-mold foam molding method) for producing a foam having a desired shape by fusing and integrating the foam particles. In addition, a sheet-like thing shows the form which aggregated within the space | interval of the reinforcement fiber surfaces within 20 micrometers.

(Fiber reinforced composite)
The above fiber reinforced foam is excellent in mechanical strength and light weight such as compressive strength and bending strength, so it is used for transportation equipment such as automobiles, aircraft, railway vehicles or ships, home appliances, information terminals, wind power generation. Can be used as a core material in a wide range of applications such as parts, industrial machinery, medical equipment, furniture, etc. Especially as a core of fiber-reinforced composites for blades of automobile parts (floor panels, etc.) and windmills. It can be used suitably.
The fiber reinforced composite can have various shapes such as a rectangular shape, a square shape, other polygonal shapes, a circular shape, an elliptical shape, a semicircular shape, a crescent shape, and an indeterminate shape in plan view.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples. The measuring methods of various measured values in the examples are described below.
(density)
The density of the foam refers to a value measured according to JIS K7222: 1999 “Foamed plastics and rubbers—Measurement of apparent density”.

(Maximum point intensity)
Ten strip samples (a strip sample having a lateral dimension of 15 mm, a thickness of 20 mm, and a depth dimension of 100 mm) are collected from the fiber reinforced foam or the fiber reinforced composite. Using this sample, the “maximum point load” is measured, and the “maximum point load” is divided by the mass of the sample to obtain “mass efficiency”.
The maximum point strength of fiber reinforced foam and the like is measured using a small tabletop testing machine (trade name “FGS-1000TV / 1000N + FGP-100” manufactured by Nidec Symposium) and software “FGS-TV Ver2” for small tabletop testing machines. taking measurement.
As the jig, “FGTT-531” manufactured by Nidec Symposium is used.
A strip-shaped sample is placed on a support table, and the maximum point strength is measured under the conditions of a load cell 1000N, a test speed of 5 mm / min, a tip jig 5R of the support table, and an opening width of 80 mm. The value obtained by dividing by mass is mass efficiency.

Example 1
Modified polyethylene terephthalate containing 1,4-cyclohexanedimethanol as part of the diol unit (modified PET, trade name “EN099” manufactured by Eastman, melting point: 238.5 ° C., glass transition temperature Tg: 75.6 ° C.) 100 Modified by containing 1.8 parts by weight of a masterbatch (polyethylene terephthalate content: 60% by weight, talc content: 40% by weight) and 0.26 parts by weight of pyromellitic anhydride containing talc in polyethylene terephthalate The polyethylene terephthalate composition was supplied to a single screw extruder having a diameter of 65 mm and an L / D ratio of 35, and melt kneaded at 290 ° C.
Next, in the middle of the single-screw extruder, butane containing 35% by weight of isobutane and 65% by weight of normal butane is melted so that the total amount of modified polyethylene terephthalate and polyethylene terephthalate is 1.3 parts by weight. The modified polyethylene terephthalate composition was press-fitted and uniformly dispersed in the modified polyethylene terephthalate composition.

Thereafter, after the molten modified polyethylene terephthalate composition was cooled to 280 ° C. at the front end of the extruder, the modified polyethylene terephthalate composition was extruded and foamed from a nozzle of a multi-nozzle mold attached to the front end of the extruder. . The multi-nozzle mold had a nozzle having a diameter of 1 mm at the outlet.
The extrudate extruded from the outlet of the nozzle of the multi-nozzle mold was cut with a rotating blade and immediately cooled to produce expanded particles having a substantially spherical re-expandability. The extrudate consisted of an unfoamed portion immediately after being extruded from the nozzle of the multi-nozzle mold, and a foamed portion in the process of foaming continuous with the unfoamed portion. The extrudate was cut in the unfoamed portion at the open end of the outlet portion of the nozzle. The expanded particles had re-expandability.

Subsequently, a prepreg formed by a twill weave made of carbon fiber (CF) and impregnated with a thermosetting resin (epoxy resin 40 wt%, indicated as EP in the table) (trade name “Pyro” manufactured by Mitsubishi Rayon Co., Ltd.) Fill Prepreg TR3523-395GMP ”, basis weight: 200 g / m ² , thickness: 0.23 mm) was cut into a length of 4 mm and a width of 2 mm, and dry blended with the foamed particles.
A hydraulic press with a male 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 200 mm in length, 200 mm in width, and 20 mm in height is formed between the male and male molds. The dry blended expanded particles and the cut prepreg were filled into the mold so as to have the blending amounts shown in Table 1. After filling, heat pressing was performed at 140 ° C. for 5 minutes, and then the mold was opened and released to obtain a fiber-reinforced foam. A cross-sectional photograph of the obtained fiber reinforced foam is shown in FIG. 3 (dotted lines in the figure indicate the grain boundaries of the expanded particles). In addition, the average thickness of the non-foamed layer of the obtained fiber reinforced foam was 0.01 mm.

(Examples 2 to 4 and Comparative Example 1)
A fiber-reinforced foam was obtained in the same manner as in Example 1 except that the raw materials were blended in the amounts shown in Table 1.

(Example 5)
As a fiber reinforced resin material, a face material in which a twill weave made of carbon fiber is impregnated with a thermosetting resin (trade name “Pyrofil Prepreg TR3523-395GMP” manufactured by Mitsubishi Rayon Co., Ltd., basis weight: 200 g / m ² , thickness: Two sheets (0.23 mm, CFRP) were prepared. The face material had a planar square shape with a side of 250 mm. The face material contained 50% by mass of an uncured epoxy resin as a thermosetting resin.
Two face materials were superposed on each of the front and back surfaces so that the length directions of the warp yarns made an angle of 90 ° to each other to obtain a multilayer face material.

Subsequently, a multilayer body of the multilayer surface material and the fiber reinforced foam (core material) of Example 1 is disposed between the male and female molds, and the male and male molds are clamped to perform press molding, thereby performing the multilayer surface material. A fiber-reinforced composite was obtained by thermally bonding to the core material.
Details of the press molding conditions are as follows. The pressing temperature was controlled so that the laminate was held at 145 ° C., and the fluidity was maintained without curing the epoxy resin contained in the multilayer face material. Thereafter, the laminate is heated at 145 ° C. for 5 minutes to cure the uncured epoxy resin contained in the multilayer face material, and the fibers of the multilayer face material are bound and fixed with a cured epoxy resin. The layer face material was laminated and integrated on both surfaces of the core material to produce a fiber reinforced composite (curing step). Thereafter, the fiber reinforced composite was cooled to 30 ° C. or lower, and then the male and female molds were opened to take out the fiber reinforced composite.

(Examples 6-8 and Comparative Examples 2-3)
A fiber-reinforced composite was obtained in the same manner as in Example 5 except that it was blended in the amounts shown in Table 1.
(Example 10)
Instead of the fiber reinforced resin material of Example 1, carbon fiber cloth TR3523M (manufactured by Mitsubishi Rayon Co., Ltd., basis weight: 200 g / m ² , thickness: 0.20 mm) and copolymer polyester resin (manufactured by Tokyo Ink Co., Ltd.) Except that the name “G125”, melting point: 100.6 ° C., density: 1.28 g / cm ³ , average particle size: 0.1 mm, indicated as PE in the table) in the amounts shown in Table 1. A fiber reinforced composite was obtained in the same manner as in Example 1.

  From Table 1, the fiber-reinforced foam contains 1 to 40% by volume of the reinforcing fiber, and the fiber-reinforced foam contains the thermoplastic resin foam in which the reinforcing fiber is at least partially present in the binder resin, the binder resin, and the reinforcing fiber. It can be seen that excellent mechanical properties can be realized with a body.

1 expanded particles, 2 thermosetting resin, 3 short fibers, 4 long fibers

Claims (7)

A fiber reinforced foam including a thermoplastic resin foam, a binder resin, and reinforcing fibers, wherein the fiber reinforced foam includes 1 to 40% by volume of the reinforcing fibers, and the reinforcing fibers are at least partially in the binder resin. Exists ,
The thermoplastic foam is a fusion product of a plurality of foam particles,
The binder resin and the reinforcing fiber are derived from a fiber reinforced resin containing a binder resin and a reinforcing fiber, and the reinforcing fiber is a face material selected from a sheet-like material composed of a woven fabric, a nonwoven fabric, and a fiber bundle, fiber reinforced foam surface material is characterized Rukoto which have a surface area of up to face the 0.01~100mm ^2. The fiber-reinforced foam according to claim 1 , wherein the reinforcing fibers are long fibers having a fiber length of 1 mm or more, the foamed particles have a non-foamed layer on the surface, and the long fibers are present on the non-foamed layer. . The fiber reinforced foam according to claim 1 or 2 , wherein the reinforcing fibers include at least a part of long fibers in contact with three or more foamed particles. The fiber-reinforced foam according to any one of claims 1 to 3 , wherein the reinforcing fiber is made of carbon fiber or glass fiber. A fiber-reinforced composite comprising the fiber-reinforced foam according to any one of claims 1 to 4 as a core material. It is a manufacturing method of the fiber reinforced foam according to any one of claims 1 to 4 ,
When the thermoplastic resin foam is obtained by molding, and the binder resin is a thermosetting resin, the binder resin is obtained by thermosetting from a thermosetting resin simultaneously with the molding. Body manufacturing method. The thermoplastic resin foam is obtained by molding foamed particles, and the binder resin contains reinforcing fibers that are face materials selected from a sheet-like material composed of a woven fabric, a nonwoven fabric, and a fiber bundle. 6. A method for producing a fiber-reinforced foam according to item 6 .