JP2010083079A - Method of manufacturing honeycomb core - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a honeycomb core having superior mechanical strength and water resistance with high productivity. <P>SOLUTION: The method comprises impregnating a reinforced fiber with a polymerizable composition comprising a cycloolefin monomer, a polymerization catalyst and a cross-linking agent, polymerizing the polymerizable composition to obtain a prepreg, forming into a corrugated shape and laminating and cross-linking the resultant product to obtain a honeycomb core having superior mechanical strength and water resistance. The honeycomb core having superior mechanical strength can be manufactured with high productivity by using reinforced fibers which has a high ratio of fibers and consists of a one-way material. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a manufacturing method excellent in productivity of a honeycomb core having high mechanical strength.

  Honeycomb cores are formed by continuously forming hollow cells of various shapes next to each other in the outer circumferential direction, and are lightweight and excellent in mechanical strength. It is used in a wide range of applications. As the base material of the honeycomb core, aluminum foil, kraft paper or the like is used. However, although a honeycomb structure made of aluminum foil has high strength, when it is used for an aircraft member or the like, further reduction in weight is required. Moreover, although the honeycomb core made of kraft paper is light and inexpensive, there are problems such as insufficient mechanical strength and large shrinkage due to humidity. On the other hand, an FRP honeycomb core made of a matrix resin and reinforcing fibers has recently been proposed as a honeycomb core that satisfies both of the two characteristics of being lightweight and excellent in mechanical strength.

  For example, Patent Document 1 describes an aramid sheet in which a fiber and pulp obtained by mixing and heating a thermosetting resin such as a phenol resin, aramid fiber, and aramid pulp are heated. An aramid honeycomb is described in which a corrugated sheet of this aramid sheet is formed into a corrugated shape, and then a plurality of sheets are laminated via an adhesive and further immersed in an impregnating liquid such as a phenol resin. However, since the aramid honeycomb obtained by this method has low water resistance, there is a problem that the mechanical strength is lowered when used under high humidity.

Patent Document 2 describes the following invention in order to solve such a problem. That is, a carbon fiber base cloth is impregnated with an epoxy resin, formed into a honeycomb shape, and then a plurality of corrugated sheets that are cross-linked and cured are laminated via an adhesive, and the adhesive is cured to obtain a laminate. Further, a honeycomb structure is described in which this laminate is impregnated with an N-methylpyrrolidone solution of a phenol resin prepolymer, the solvent is evaporated, the resin is cured, and this impregnation-evaporation-curing is repeated. Furthermore, in Patent Document 3, a carbon fiber woven fabric is impregnated with a phenol resin, and then a prepreg obtained by polymerization is laminated through an epoxy resin adhesive, stretched and formed into a honeycomb shape, and then cured. A honeycomb core is described.
Japanese Patent Laid-Open No. 10-278145 JP-A-8-187802 JP 2001-9942 A

However, according to the knowledge of the present inventors, the honeycomb cores described in Patent Documents 2 and 3 use a carbon fiber base fabric, so that the water resistance is improved compared to an aramid fiber. The water absorption rate of the resin to be obtained is high, and the water resistance of the resulting honeycomb core as a whole has not been sufficient. Moreover, since it took a long time to cure the resin, it was found that there was a problem in productivity. Furthermore, the present inventors used unreinforced resin in the honeycomb cores described in Patent Documents 2 and 3 from the viewpoint of mechanical strength, particularly when reinforcing fibers aligned in one direction among the reinforcing fibers were used. When the prepreg made of is folded into a corrugated shape, cracks occur from the end of the prepreg, so that there is a problem that cracks remain in the obtained honeycomb core, the mechanical strength of the honeycomb core decreases, and the appearance deteriorates. all right.
An object of the present invention is to provide a method for manufacturing a honeycomb core having excellent mechanical strength and water resistance and high productivity.

  As a result of intensive studies in view of the above problems, the present inventors have impregnated a polymerizable composition containing a cycloolefin monomer, a polymerization catalyst, and a crosslinking agent into a carbon fiber, molded it into a corrugated shape, and then crosslinked it. It has been found that the honeycomb core obtained is excellent in mechanical strength and water resistance. Further, it has been found that a honeycomb core excellent in mechanical strength can be produced with good productivity by using unidirectional carbon fibers having a high fiber ratio.

Thus, according to the present invention, the following (1) to (4) are provided.
(1) impregnating a polymerizable composition comprising a cycloolefin monomer and a polymerization catalyst into a reinforcing fiber, polymerizing the prepreg, a step of forming the prepreg into a corrugated shape, and laminating the obtained molded product (2) The method for manufacturing a honeycomb core according to (1), wherein the polymerizable composition includes a cross-linking agent.
(3) The method for manufacturing a honeycomb core according to (1) or (2), wherein the reinforcing fibers are reinforcing fibers arranged in one direction.
(4) The method for manufacturing a honeycomb core according to any one of (1) to (3), wherein the reinforcing fibers are carbon fibers.

  According to the present invention, a honeycomb core excellent in mechanical strength and water resistance can be obtained with high productivity. Moreover, the honeycomb core of the present invention can be suitably used in the fields of vehicles such as automobiles and airplanes, and sports, civil engineering, and architecture.

(Cycloolefin monomer)
The cycloolefin monomer used in the present invention is a compound having a ring structure formed of carbon atoms and having one polymerizable carbon-carbon double bond in the ring structure. As used herein, “polymerizable carbon-carbon double bond” refers to a carbon-carbon double bond capable of chain polymerization (ring-opening polymerization). There are various types of ring-opening polymerization, such as ionic polymerization, radical polymerization, and metathesis polymerization. In the present invention, it usually refers to metases ring-opening polymerization.

Examples of the ring structure of the cycloolefin monomer include monocycles, polycycles, condensed polycycles, bridged rings, and combination polycycles thereof. Although there is no limitation in particular in carbon number which comprises each ring structure, Usually, 4-30 pieces, Preferably it is 5-20 pieces, More preferably, it is 5-15 pieces.
The cycloolefin monomer may have a hydrocarbon group having 1 to 30 carbon atoms such as an alkyl group, an alkenyl group, an alkylidene group or an aryl group, or a polar group such as a carboxyl group or an acid anhydride group as a substituent. However, from the viewpoint of improving the water resistance of the resulting honeycomb core, those having no polar group, that is, comprising only carbon atoms and hydrogen atoms are preferred.

  As the cycloolefin monomer, either a monocyclic cycloolefin monomer or a polycyclic cycloolefin monomer can be used. From the viewpoint of highly balancing the heat resistance, mechanical strength, and water resistance of the resulting honeycomb core, a polycyclic cycloolefin monomer is preferred. As the polycyclic cycloolefin monomer, a norbornene-based monomer is particularly preferable. The “norbornene monomer” refers to a cycloolefin monomer having a norbornene ring structure in the molecule. For example, norbornenes, dicyclopentadiene, tetracyclododecene and the like can be mentioned.

  Cycloolefin monomers are divided into those having no crosslinkable carbon-carbon unsaturated bonds and those having one or more crosslinkable carbon-carbon unsaturated bonds. As used herein, “crosslinkable carbon-carbon unsaturated bond” refers to a carbon-carbon unsaturated bond that does not participate in ring-opening polymerization and can participate in a crosslinking reaction. The crosslinking reaction is a reaction that forms a bridge structure, and there are various forms such as a condensation reaction, an addition reaction, a radical reaction, and a metathesis reaction. In the present invention, usually, a radical crosslinking reaction or a metathesis crosslinking reaction. In particular, it refers to a radical crosslinking reaction. Examples of the crosslinkable carbon-carbon unsaturated bond include carbon-carbon unsaturated bonds other than aromatic carbon-carbon unsaturated bonds, that is, aliphatic carbon-carbon double bonds or triple bonds. Usually refers to an aliphatic carbon-carbon double bond. In the cycloolefin monomer having one or more crosslinkable carbon-carbon unsaturated bonds, the position of the unsaturated bond is not particularly limited, and within the ring structure formed of carbon atoms, any other than the ring structure For example, at the end or inside of the side chain.

  Examples of cycloolefin monomers having no crosslinkable carbon-carbon unsaturated bond include cyclopentene, 3-methylcyclopentene, 4-methylcyclopentene, 3,4-dimethylcyclopentene, 3,5-dimethylcyclopentene, and 3-chlorocyclopentene. , Cyclohexene, 3-methylcyclohexene, 4-methylcyclohexene, 3,4-dimethylcyclohexene, 3-chlorocyclohexene, cycloheptene and other monocyclic cycloolefin monomers; norbornene, 5-methylnorbornene, 5-ethylnorbornene 5-propylnorbornene, 5,6-dimethylnorbornene, 1-methylnorbornene, 7-methylnorbornene, 5,5,6-trimethylnorbornene, 5-phenylnorbornene, 1,4,5,8-dimethano 1,2,3,4,4a, 5,8,8a-octahydronaphthalene, 2-methyl-1,4,5,8-dimethano-1,2,3,4,4a, 5,8,8a- Octahydronaphthalene, 2-ethyl-1,4,5,8-dimethano-1,2,3,4,4a, 5,8,8a-octahydronaphthalene, 2,3-dimethyl-1,4,5 8-Dimethano-1,2,3,4,4a, 5,8,8-octahydronaphthalene, 2-hexyl-1,4,5,8-dimethano-1,2,3,4,4a, 5 8,8a-octahydronaphthalene, 2-ethylidene-1,4,5,8-dimethano-1,2,3,4,4a, 5,8,8a-octahydronaphthalene, 2-fluoro-1,4 5,8-dimethano-1,2,3,4,4a, 5,8,8a-octahydronaphthalene, 1 5-Dimethyl-1,4,5,8-dimethano-1,2,3,4,4a, 5,8,8a-octahydronaphthalene, 2-cyclohexyl-1,4,5,8-dimethano- 1,2,3,4,4a, 5,8,8a-octahydronaphthalene, 2,3-dichloro-1,4,5,8-dimethano-1,2,3,4,4a, 5,8, 8a-octahydronaphthalene, 2-isobutyl-1,4,5,8-dimethano-1,2,3,4,4a, 5,8,8a-octahydronaphthalene, 1,2-dihydrodicyclopentadiene, 5 -Chloronorbornene, 5,5-dichloronorbornene, 5-fluoronorbornene, 5,5,6-trifluoro-6-trifluoromethylnorbornene, 5-chloromethylnorbornene, 5-methoxynorbornene, 5,6-dicarboxene Norbornene monomers such as silnorbornene anhydrate, 5-dimethylaminonorbornene, 5-cyanonorbornene and the like can be mentioned, and norbornene monomers having no crosslinkable carbon-carbon unsaturated bond are preferable.

Examples of the cycloolefin monomer having one or more crosslinkable carbon-carbon unsaturated bonds include 3-vinylcyclohexene, 4-vinylcyclohexene, 1,3-cyclopentadiene, 1,3-cyclohexadiene, 1,4- Monocyclic cycloolefin monomers such as cyclohexadiene, 5-ethyl-1,3-cyclohexadiene, 1,3-cycloheptadiene, 1,3-cyclooctadiene; 5-ethylidene-2-norbornene, 5-methylidene Norbornene monomers such as 2-norbornene, 5-isopropylidene-2-norbornene, 5-vinylnorbornene, 5-allylnorbornene, 5,6-diethylidene-2-norbornene, dicyclopentadiene, 2,5-norbornadiene; Preferably crosslinkable carbon- The containing unsaturated bonds is a norbornene-based monomer having one or more.
These cycloolefin monomers can be used alone or in combination of two or more.

As the cycloolefin monomer used in the present invention, one containing a cycloolefin monomer having one or more crosslinkable carbon-carbon unsaturated bonds is suitable because the mechanical strength of the resulting honeycomb core is improved.
In the cycloolefin monomer blended in the polymerizable composition of the present invention, a blend of a cycloolefin monomer having one or more crosslinkable carbon-carbon unsaturated bonds and a cycloolefin monomer having no crosslinkable carbon-carbon unsaturated bonds The ratio is appropriately selected as desired, but in a weight ratio (cycloolefin monomer having at least one crosslinkable carbon-carbon unsaturated bond / cycloolefin monomer having no crosslinkable carbon-carbon unsaturated bond), usually, It is in the range of 5/95 to 100/0, preferably 10/90 to 90/10, more preferably 15/85 to 70/30. When the blending ratio is within such a range, the obtained honeycomb core is suitable because properties such as mechanical strength, heat resistance, interlayer adhesion, and water resistance are highly balanced.

(Polymerization catalyst)
The polymerization catalyst used in the present invention is not particularly limited as long as it can polymerize the cycloolefin monomer, but the polymerizable composition of the present invention is directly subjected to bulk polymerization in the production of the prepreg described below. It is preferable to use a metathesis polymerization catalyst.

  Examples of the metathesis polymerization catalyst include a complex formed by bonding a plurality of ions, atoms, polyatomic ions, compounds, etc. with a transition metal atom as a central atom, which is capable of metathesis ring-opening polymerization of the cycloolefin monomer. It is done. As transition metal atoms, atoms of Group 5, Group 6 and Group 8 (according to the long-period periodic table; the same shall apply hereinafter) are used. Although the atoms of each group are not particularly limited, examples of the Group 5 atom include tantalum. Examples of the Group 6 atom include molybdenum and tungsten. Examples of the Group 8 atom include Examples thereof include ruthenium and osmium. Among them, group 8 ruthenium and osmium are preferable as the transition metal atom. That is, the metathesis polymerization catalyst used in the present invention is preferably a complex having ruthenium or osmium as a central atom, and more preferably a complex having ruthenium as a central atom. As the complex having ruthenium as a central atom, a ruthenium carbene complex in which a carbene compound is coordinated to ruthenium is preferable. Here, the “carbene compound” is a general term for compounds having a methylene free group, and refers to a compound having an uncharged divalent carbon atom (carbene carbon) as represented by (> C :). Since ruthenium carbene complex is excellent in catalytic activity during bulk polymerization, when the prepreg is obtained by subjecting the polymerizable composition of the present invention to bulk polymerization, the resulting prepreg has little odor derived from unreacted monomers and is produced. Good quality prepreg can be obtained. In addition, it is relatively stable to oxygen and moisture in the air and is not easily deactivated, so that it can be used even in the atmosphere.

  The ruthenium carbene complex preferably has at least one carbene compound having a heterocyclic structure as a ligand because the mechanical strength and impact resistance of the obtained prepreg and honeycomb core can be highly balanced. . As a hetero atom which comprises a heterocyclic structure, an oxygen atom, a nitrogen atom, etc. are mentioned, for example, Preferably it is a nitrogen atom. Moreover, as a heterocyclic structure, an imidazoline ring structure or an imidazolidine ring structure is preferable. Specific examples of the compound having such a heterocyclic structure include 1,3-di (1-adamantyl) imidazolidin-2-ylidene, 1,3-dimesityloctahydrobenzimidazol-2-ylidene, 1,3- Di (1-phenylethyl) -4-imidazoline-2-ylidene, 1,3,4-triphenyl-2,3,4,5-tetrahydro-1H-1,2,4-triazole-5-ylidene, 1 , 3-dicyclohexylhexahydropyrimidin-2-ylidene, N, N, N ′, N′-tetraisopropylformamidinylidene, 1,3-dimesitylimidazolidine-2-ylidene, 1,3-dicyclohexylimidazolidine 2-ylidene, 1,3-diisopropyl-4-imidazoline-2-ylidene, 1,3-dimesityl-2,3-dihydrobenzii Such as imidazole-2-ylidene and the like.

  Specific examples of a suitable ruthenium carbene complex used as a metathesis polymerization catalyst in the present invention include benzylidene (1,3-dimesityrylimidazolidine-2-ylidene) (tricyclohexylphosphine) ruthenium dichloride, (1,3 -Dimesitylimidazolidin-2-ylidene) (3-methyl-2-buten-1-ylidene) (tricyclopentylphosphine) ruthenium dichloride, benzylidene (1,3-dimesityl-octahydrobenzimidazol-2-ylidene) Tricyclohexylphosphine) ruthenium dichloride, benzylidene [1,3-di (1-phenylethyl) -4-imidazoline-2-ylidene] (tricyclohexylphosphine) ruthenium dichloride, benzylidene (1,3-dimesityl-2,3- Hydrobenzimidazol-2-ylidene) (tricyclohexylphosphine) ruthenium dichloride, benzylidene (tricyclohexylphosphine) (1,3,4-triphenyl-2,3,4,5-tetrahydro-1H-1,2,4- Triazole-5-ylidene) ruthenium dichloride, (1,3-diisopropylhexahydropyrimidin-2-ylidene) (ethoxymethylene) (tricyclohexylphosphine) ruthenium dichloride, benzylidene (1,3-dimesityloimidazolidine-2-ylidene ) Ruthenium carbene complexes having a carbene compound having a heterocyclic structure and other neutral electron donors as ligands such as pyridine ruthenium dichloride. Here, the “neutral electron donor” refers to a ligand having a neutral charge when separated from the central metal atom. A carbene compound having a heterocyclic structure is also a kind of neutral electron donor.

  The metathesis polymerization catalysts may be used alone or in combination of two or more. The amount of the metathesis polymerization catalyst used is a molar ratio (metal atom in the metathesis polymerization catalyst: cycloolefin monomer) and is usually from 1: 2,000 to 1: 2,000,000, preferably from 1: 5,000 to 1. : 1,000,000, more preferably in the range of 1: 10,000 to 1: 500,000.

  If desired, the metathesis polymerization catalyst can be used dissolved or suspended in a small amount of an inert solvent. Such solvents include chain aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane, liquid paraffin and mineral spirits; cyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, trimethylcyclohexane, ethylcyclohexane, diethylcyclohexane , Decahydronaphthalene, dicycloheptane, tricyclodecane, hexahydroindene, cyclooctane and other alicyclic hydrocarbons; benzene, toluene, xylene and other aromatic hydrocarbons; indene, tetrahydronaphthalene and other alicyclic and aromatic rings A nitrogen-containing hydrocarbon such as nitromethane, nitrobenzene, and acetonitrile; an oxygen-containing hydrocarbon such as diethyl ether and tetrahydrofuran; and the like. Among these, it is preferable to use a chain aliphatic hydrocarbon, an alicyclic hydrocarbon, an aromatic hydrocarbon, and a hydrocarbon having an alicyclic ring and an aromatic ring.

(Crosslinking agent)
The crosslinking agent used in the present invention is used for the purpose of inducing a crosslinking reaction in a cycloolefin polymer obtained by subjecting the polymerizable composition of the present invention to a polymerization reaction. Accordingly, the cycloolefin polymer becomes a post-crosslinkable thermoplastic resin. In the present invention, a radical generator is usually preferably used as the crosslinking agent. Examples of the radical generator include organic peroxides, diazo compounds, and nonpolar radical generators, and organic peroxides and nonpolar radical generators are preferable.

  Examples of the organic peroxide include hydroperoxides such as t-butyl hydroperoxide, p-menthane hydroperoxide, cumene hydroperoxide; dicumyl peroxide, t-butylcumyl peroxide, α, α′-bis (t- Butylperoxy-m-isopropyl) benzene, di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) -3-hexyne, 2,5-dimethyl-2,5-di ( dialkyl peroxides such as t-butylperoxy) hexane; diacyl peroxides such as dipropionyl peroxide and benzoyl peroxide; 2,2-di (t-butylperoxy) butane, 1,1-di (t-hexylperoxy) cyclohexane, 1,1-di (t-butylperoxy) -2-methyl Peroxyketals such as chlorocyclohexane and 1,1-di (t-butylperoxy) cyclohexane; peroxyesters such as t-butylperoxyacetate and t-butylperoxybenzoate; t-butylperoxyisopropylcarbonate, di (isopropylperoxy) ) Peroxycarbonates such as dicarbonate; alkylsilyl peroxides such as t-butyltrimethylsilyl peroxide; and the like. In particular, when a metathesis polymerization catalyst is used as the polymerization catalyst, dialkyl peroxides and peroxyketals are preferable in that the inhibition of the metathesis polymerization reaction is small.

  Examples of the diazo compound include 4,4'-bisazidobenzal (4-methyl) cyclohexanone and 2,6-bis (4'-azidobenzal) cyclohexanone.

  Nonpolar radical generators include 2,3-dimethyl-2,3-diphenylbutane, 3,4-dimethyl-3,4-diphenylhexane, 1,1,2-triphenylethane, 1,1,1- And triphenyl-2-phenylethane.

When the crosslinking agent used in the present invention is a radical generator, the 1-minute half-life temperature is appropriately selected depending on the conditions of curing (crosslinking of a cycloolefin polymer obtained by subjecting the polymerizable composition of the present invention to a polymerization reaction). However, it is usually in the range of 100 to 300 ° C, preferably 150 to 250 ° C, more preferably 160 to 230 ° C. Here, the half-life temperature for 1 minute is a temperature at which half of the radical generator decomposes in 1 minute. For the 1 minute half-life temperature of the radical generator, refer to, for example, a product catalog (http://www.nof.co.jp/upload_public/sogo/B0100.pdf) introduced on the homepage of Nippon Oil & Fats Co., Ltd. Good.
The radical generators can be used alone or in combination of two or more. The amount of the radical generator used in the polymerizable composition of the present invention is usually 0.01 to 10 parts by weight, preferably 0.1 to 10 parts by weight, more preferably 0 to 100 parts by weight of the cycloolefin monomer. The range is from 5 to 5 parts by weight.

(Reinforced fiber)
The reinforcing fiber used in the present invention is not particularly limited. For example, organic fibers such as PET (polyethylene terephthalate) fiber, aramid fiber, ultrahigh molecular polyethylene fiber, polyamide (nylon) fiber, and liquid crystal polyester fiber; And inorganic fibers such as glass fibers, carbon fibers, alumina fibers, tungsten fibers, molybdenum fibers, budene fibers, titanium fibers, steel fibers, boron fibers, silicon carbide fibers, silica fibers, and the like. Among these, organic fiber, glass fiber, and carbon fiber are preferable, and carbon fiber is more preferable. In particular, the carbon fiber is excellent in compatibility with the polymerizable composition containing a cycloolefin monomer, and by uniformly impregnating the polymerizable composition, the mechanical strength, toughness, and heat resistance of the resulting honeycomb core are improved. It can be improved to a high degree and is suitable. The type of carbon fiber is not particularly limited. For example, carbon fibers produced by various conventionally known methods such as acrylic, pitch, and rayon can be used. Among them, acrylic fiber (polyacrylonitrile fiber) Acrylic carbon fiber produced using as a raw material is suitable because it does not inhibit metathesis polymerization and can improve properties such as mechanical strength, toughness and heat resistance.

  The strength characteristic of the reinforcing fiber used in the present invention is not particularly limited and is appropriately selected according to the purpose of use. The tensile strength is a strand tensile strength measured according to JIS R7601, and is usually 0.5 to 50 GPa, preferably 1 to 10 GPa, more preferably 2 to 8 GPa. The tensile modulus is a strand tensile modulus measured according to JIS R7601, and is usually in the range of 100 to 1,000 GPa, preferably 200 to 800 GPa, more preferably 300 to 700 GPa. The elongation is a strand tensile elongation measured according to JIS R7601, and is usually 0.1 to 10%, preferably 0.5 to 5%, more preferably 1 to 3%. When the strength characteristics of the reinforcing fibers are within these ranges, the mechanical strength and toughness characteristics of the resulting honeycomb core are highly balanced and suitable.

  The cross-sectional shape of the reinforcing fiber used in the present invention is not particularly limited, but is preferably substantially circular. This is because, when the cross-sectional shape is circular, when the polymerizable composition is impregnated, rearrangement of the filaments is likely to occur, and the polymerizable composition can easily penetrate between the fibers. Furthermore, since the thickness of the fiber bundle can be reduced, there is an advantage that it is easy to obtain a prepreg excellent in drapeability. Note that the cross-sectional shape is substantially circular when the ratio of the circumscribed circle radius R to the inscribed circle radius r (R / r) of the cross section is defined as the degree of deformation. Meaning one or less.

  The length of the reinforcing fiber used in the present invention is appropriately selected according to the purpose of use without any particular limitation, and either a short fiber or a long fiber can be used, but a honeycomb having higher mechanical strength and toughness. When it is desired to obtain a core, the length of the fiber is 1 cm or more, preferably 2 cm or more, more preferably 3 cm or more, and most preferably continuous fiber.

The form of the reinforcing fiber used in the present invention is not particularly limited, and can be appropriately selected from a unidirectional material in which the reinforcing fibers are aligned in one direction, a woven fabric, a nonwoven fabric, a mat, a knit, a braid, a roving, a chopped, and the like. Among these, it is preferable that it is the form of continuous fibers, such as a unidirectional material, a textile fabric, and a roving, and a unidirectional material is still more preferable. The unidirectional material is preferable because it can improve the impregnation property of the polymerizable composition to a high degree and can improve the mechanical strength of the resulting honeycomb core because of the high fiber ratio.
As the woven form, conventionally known ones can be used. For example, all of woven structures in which fibers such as plain weave, satin weave, twill weave, and triaxial weave are interlaced can be used. Moreover, as a woven fabric form, not only two-dimensional but also a stitch woven fabric and a three-dimensional woven fabric in which fibers are reinforced in the thickness direction of the woven fabric can be used.

When the reinforcing fiber used in the present invention is used in a woven fabric or the like, it is used as a fiber bundle yarn. In this case, the number of filaments in one fiber bundle yarn is not particularly limited, but is preferably 1,000 to 100,000, more preferably 5,000 to 50,000, and still more preferably 10, The range is from 000 to 30,000.
These reinforcing fibers can be used alone or in combination of two or more, and the amount used is appropriately selected according to the purpose of use, but the reinforcing fiber content in the obtained prepreg is usually 10%. It is selected to be in the range of -90% by weight, preferably 20-85% by weight, more preferably 30-80% by weight. The mechanical strength and toughness characteristics of the honeycomb core obtained when the reinforcing fiber content is in this range are highly balanced and suitable.

(Polymerizable composition)
The polymerizable composition used in the present invention includes, in addition to the cycloolefin monomer, the polymerization catalyst, and the crosslinking agent described above, if desired, a polymerization regulator, a polymerization reaction retarding agent, a chain transfer agent, a crosslinking aid, a filler, An anti-aging agent, an elastomer material, and other compounding agents can be blended.

  The polymerization regulator is blended for the purpose of controlling the metathesis polymerization activity or improving the metathesis polymerization reaction rate. For example, trialkoxyaluminum, triphenoxyaluminum, dialkoxyalkylaluminum, alkoxydialkylaluminum, Examples include trialkylaluminum, dialkoxyaluminum chloride, alkoxyalkylaluminum chloride, dialkylaluminum chloride, trialkoxyscandium, tetraalkoxytitanium, tetraalkoxytin, and tetraalkoxyzirconium. These polymerization regulators can be used alone or in combination of two or more. The blending amount of the polymerization regulator is usually 1: 0.05 to 1: 100, preferably 1: 0.2 to 1:20, in a molar ratio of (metal atom in the metathesis polymerization catalyst: polymerization regulator). More preferably, it is in the range of 1: 0.5 to 1:10.

  It is preferable for the polymerizable composition used in the present invention to contain a polymerization reaction retarder because the increase in viscosity can be suppressed and the reinforcing fiber can be uniformly impregnated with the polymerizable composition. Polymerization retarders include phosphine compounds such as triphenylphosphine, tributylphosphine, trimethylphosphine, triethylphosphine, dicyclohexylphosphine, vinyldiphenylphosphine, allyldiphenylphosphine, triallylphosphine, styryldiphenylphosphine; Lewis bases such as aniline and pyridine Etc. can be used.

  Among these polymerization reaction retarders, a phosphine compound is preferable because of its great effect of suppressing the progress of the polymerization reaction at room temperature or lower, and triphenylphosphine, triethylphosphine, dicyclohexylphosphine, and vinyldiphenylphosphine are more preferable. These polymerization reaction retarders can be used alone or in combination of two or more, and the blending amount is usually a molar ratio of (metal atom in the metathesis polymerization catalyst: polymerization reaction retarder), It is in the range of 1: 0.01 to 1: 100, preferably 1: 0.1 to 1:10, more preferably 1: 0.1 to 1: 5.

The chain transfer agent is a compound that can participate in ring-opening polymerization and has one aliphatic carbon-carbon double bond that can be bonded to the terminal of a polymer obtained by subjecting the polymerizable composition of the present invention to a polymerization reaction. . Examples of the double bond include a terminal vinyl group. The chain transfer agent may have one or more crosslinkable carbon-carbon unsaturated bonds.
Specific examples of the chain transfer agent include 1-hexene, 2-hexene, styrene, vinylcyclohexane, allylamine, glycidyl acrylate, allyl glycidyl ether, ethyl vinyl ether, methyl vinyl ketone, 2- (diethylamino) ethyl acrylate, 4-vinyl. Chain transfer agent having no crosslinkable carbon-carbon unsaturated bond such as aniline; divinylbenzene, vinyl methacrylate, allyl methacrylate, styryl methacrylate, allyl acrylate, undecenyl methacrylate, styryl acrylate, ethylene glycol diacrylate A chain transfer agent having one crosslinkable carbon-carbon unsaturated bond, a chain transfer agent having two or more crosslinkable carbon-carbon unsaturated bonds, such as allyltrivinylsilane and allylmethyldivinylsilane; Et That. Among these, in order to highly balance the mechanical strength of the obtained honeycomb core and the shapeability of the prepreg, those having one or more crosslinkable carbon-carbon unsaturated bonds in the molecule are preferable. Those having one carbon-carbon unsaturated bond are more preferred. Among such chain transfer agents, chain transfer agents having one vinyl group and one methacryl group are preferable, and vinyl methacrylate, allyl methacrylate, styryl methacrylate, allyl acrylate, undecenyl methacrylate, and the like are particularly preferable.
These chain transfer agents can be used alone or in combination of two or more. The amount used is usually 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight, based on 100 parts by weight of the cycloolefin monomer.

  In the invention, by adding a crosslinking aid to the polymerizable composition, the impregnation property of the polymerizable composition into the reinforcing fibers can be improved to a high degree, and the shapeability and mechanical strength of the honeycomb core obtained by crosslinking can be improved. It can be highly balanced and is suitable. As the crosslinking aid, a polyfunctional crosslinking aid having two or more crosslinkable carbon-carbon unsaturated bonds that can participate in the crosslinking reaction induced by the crosslinking agent without involving in the ring-opening polymerization is suitably used. . Such a crosslinkable carbon-carbon unsaturated bond is preferably present in the compound constituting the crosslinking aid, for example, as a terminal vinylidene group, particularly as an isopropenyl group or a methacryl group, particularly as a methacryl group.

  Specific examples of the crosslinking aid include, for example, a polyfunctional crosslinking aid having two or more isopropenyl groups such as p-diisopropenylbenzene, m-diisopropenylbenzene, and o-diisopropenylbenzene; ethylene dimethacrylate 1,3-butylene dimethacrylate, 1,4-butylene dimethacrylate, 1,6-hexanediol dimethacrylate, polyethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, diethylene glycol dimethacrylate 2,2′-bis (4-methacryloxydiethoxyphenyl) propane, trimethylolpropane trimethacrylate, pentaerythritol trimethacrylate, etc. Polyfunctional coagent having a group 2 or more; and the like. Among these, as the crosslinking aid, a polyfunctional crosslinking aid having two or more methacryl groups is preferable. Of the polyfunctional crosslinking aids having two or more methacrylic groups, polyfunctional crosslinking aids having three methacrylic groups such as trimethylolpropane trimethacrylate and pentaerythritol trimethacrylate are more preferred.

  These crosslinking aids can be used alone or in combination of two or more. The usage-amount of a crosslinking adjuvant is 0.1-100 weight part normally with respect to 100 weight part of cycloolefin monomers, Preferably it is 0.5-50 weight part, More preferably, it is 1-30 weight part.

  The filler is not particularly limited as long as it is generally used industrially, and either an inorganic filler or an organic filler can be used, but an inorganic filler is preferred. Examples of the inorganic filler include metal particles such as iron, copper, nickel, gold, silver, aluminum, lead, and tungsten; carbon particles such as carbon black, graphite, activated carbon, and carbon balloon; silica, silica balloon, alumina, Inorganic oxide particles such as titanium oxide, iron oxide, zinc oxide, magnesium oxide, tin oxide, beryllium oxide, barium ferrite, strontium ferrite; inorganic carbonate particles such as calcium carbonate, magnesium carbonate, sodium hydrogen carbonate; calcium sulfate, etc. Inorganic sulfate particles; inorganic silicate particles such as talc, clay, mica, kaolin, fly ash, montmorillonite, calcium silicate, glass, glass balloon; titanate particles such as calcium titanate and lead zirconate titanate, Aluminum nitride, silicon carbide particles Whiskers, and the like. Examples of the organic filler include particulate compounds such as wood flour, starch, organic pigments, polystyrene, nylon, polyolefins such as polyethylene and polypropylene, vinyl chloride, and waste plastics. These fillers can be used alone or in combination of two or more, and the blending amount thereof is usually 50 parts by weight or more, preferably 50 to 500 parts by weight with respect to 100 parts by weight of the cycloolefin monomer. More preferably, it is the range of 50-350 weight part. When the amount of the filler used is within this range, the honeycomb core can be remarkably improved in properties such as mechanical strength, heat resistance, and chemical resistance.

  As an anti-aging agent, it can be used without particular limitation, but at least one selected from the group consisting of a phenol anti-aging agent, an amine anti-aging agent, a phosphorus anti-aging agent and a sulfur anti-aging agent. By using an anti-aging agent, the oxidation deterioration resistance of the resulting honeycomb core can be highly improved without inhibiting the crosslinking reaction, which is preferable. Among these, a phenolic antiaging agent and an amine antiaging agent are preferable, and a phenolic antiaging agent is particularly preferable.

  These anti-aging agents can be used alone or in combination of two or more. The blending amount of the antioxidant is appropriately selected according to the purpose of use, but is usually 0.0001 to 10 parts by weight, preferably 0.001 to 5 parts by weight, more preferably 100 parts by weight of the cycloolefin monomer. Is in the range of 0.01 to 2 parts by weight.

  By adding an elastomer material to the polymerizable composition used in the present invention, the toughness of the resulting honeycomb core is preferably improved. Examples of the elastomer material include natural rubber, polyisoprene, polybutadiene, styrene-butadiene copolymer, chloroprene, acrylonitrile-butadiene copolymer, styrene-isoprene-styrene block copolymer, and styrene-butadiene-styrene block copolymer. , Ethylene-propylene copolymer, ethylene-propylene-diene terpolymer, ethylene-vinyl acetate copolymer, and hydrogenated products thereof. These elastomer materials can be used alone or in combination of two or more. The compounding quantity is 0.1-100 weight part normally with respect to 100 weight part of cycloolefin monomers, Preferably it is 1-50 weight part, More preferably, it is the range of 3-30 weight part.

  The polymerizable composition used in the present invention can contain other compounding agents. Examples of other compounding agents include flame retardants, colorants, light stabilizers, pigments, foaming agents, polymer modifiers, and the like. Examples of the flame retardant include phosphorus flame retardants, nitrogen flame retardants, halogen flame retardants, metal hydroxides such as aluminum hydroxide, and antimony compounds such as antimony trioxide. As the colorant, dyes, pigments and the like are used. There are various kinds of dyes, and known ones may be appropriately selected and used. These other compounding agents can be used alone or in combination of two or more, and the compounding amount is appropriately selected within a range not impairing the effects of the present invention.

  The polymerizable composition used in the present invention can be obtained by mixing the above components. As a mixing method, for example, a liquid (monomer liquid) in which a liquid (catalyst liquid) in which a polymerization catalyst is dissolved or dispersed in an appropriate solvent is mixed with a cycloolefin monomer and, if necessary, other compounding ingredients such as a crosslinking agent. ) And stirring.

(Prepreg)
The prepreg used in the present invention is formed by impregnating the above-mentioned polymerizable composition into the reinforcing fiber and then polymerizing the prepreg. The polymerization method is not particularly limited, but bulk polymerization is preferable. The cycloolefin polymer in the prepreg obtained by polymerization does not have a crosslinked structure and is dissolved in a solvent. Such a solvent is appropriately selected from solvents such as aromatic hydrocarbons such as benzene and toluene, ethers such as diethyl ether and tetrahydrofuran, and halogenated hydrocarbons such as dichloromethane and chloroform.
The molecular weight of the cycloolefin polymer is a polystyrene-reduced weight average molecular weight of a tetrahydrofuran solution measured by gel permeation chromatography, and is usually 1,000 to 1,000,000, preferably 5,000 to 500,000, More preferably, it is the range of 10,000-100,000.

  As the impregnation method, for example, a predetermined amount of the polymerizable composition is applied to the reinforcing fiber by a known method such as a spray coating method, a dip coating method, a roll coating method, a curtain coating method, a die coating method, and a slit coating method, If desired, a protective film can be stacked thereon and pressed from above with a roller or the like. After impregnating the polymerizable composition into the carbon fiber, the polymerizable composition can be bulk polymerized by heating the impregnated product to a predetermined temperature, whereby a sheet-like or film-like prepreg is obtained. Examples of the protective film used herein include resins such as polyethylene terephthalate, polypropylene, polyethylene, polycarbonate, polyethylene naphthalate, polyarylate, and nylon; metal materials such as iron, stainless steel, copper, aluminum, nickel, chromium, gold, and silver; The thing which consists of is mentioned.

  In the case where the impregnation is performed in a mold, it can be performed by placing reinforcing fibers in the mold and pouring the polymerizable composition into the mold. According to this method, a prepreg having an arbitrary shape can be obtained. As the mold used here, a conventionally known mold, for example, a mold having a split mold structure, that is, a core mold and a cavity mold, can be used, and a polymerizable composition is injected into these voids (cavities). And bulk polymerization is performed. The core mold and the cavity mold are produced so as to form a gap that matches the shape of the target prepreg. Further, the shape, material, size and the like of the mold are not particularly limited. Also, a plate-shaped mold such as a glass plate or a metal plate and a spacer having a predetermined thickness are prepared, and the polymerizable composition is injected into a space formed by sandwiching the spacer between two plate-shaped molds. A sheet-like or film-like prepreg can be obtained by curing in the mold.

  The polymerizable composition used in the present invention has a low viscosity as compared with a conventional epoxy resin solution and the like, and is excellent in impregnation with reinforcing fibers. Therefore, the obtained prepreg and honeycomb core have few voids, and the machine Excellent strength.

  In addition, when bulk polymerization is performed, the polymerizable composition has a low content of a solvent or the like that does not participate in the reaction. Therefore, a process such as removing the solvent after impregnating the reinforcing fiber is not required, which increases productivity. Excellent, no odor or swelling caused by residual solvent. In particular, when an acrylic carbon fiber is used as the reinforcing fiber, the metathesis polymerization reaction is not hindered on the surface, and preliminary drying or the like is not required, so that the production method of the present invention is further excellent in productivity. Furthermore, the cycloolefin polymer obtained by polymerization has a low content of unreacted monomers, the prepreg thus obtained has little odor, and the resulting honeycomb core is excellent in heat resistance.

  When the reinforcing fiber is a short fiber such as chopped, the reinforcing fiber can be mixed with the polymerizable composition, and then bulk polymerization can be performed. The reinforcing fiber may be added to the monomer liquid and / or the catalyst liquid before mixing the monomer liquid and the catalyst liquid, or may be added after mixing the monomer liquid and the catalyst liquid. Examples of the bulk polymerization method include a method of performing bulk polymerization in a mold in the same manner as described above. Alternatively, short fibers and woven fabrics composed of long fibers may be used in combination, and a polymerizable composition containing short fibers of reinforcing fibers may be impregnated into the woven fabric composed of long fibers in the same manner as described above before polymerization.

  The polymerizable composition of the present invention usually comprises a metathesis polymerization catalyst. The heating temperature for polymerizing the polymerizable composition is usually in the range of 50 to 250 ° C., preferably 80 to 200 ° C., more preferably 100 to 150 ° C. in any of the above methods. In addition, when a radical generator is used as the crosslinking agent, for example, it is usually at most 1 minute half-life temperature of the radical generator, preferably 10 ° C. or less, more preferably 20 ° C. or less. The polymerization time may be appropriately selected, but is usually 10 seconds to 20 minutes, preferably 10 seconds to 5 minutes. Heating the polymerization composition to a temperature in this range is preferable because a prepreg with little unreacted monomer can be obtained.

  In the present invention, when the reinforcing fiber is a unidirectional material, the prepreg is preferably used as a laminate of 4 layers or 8 layers. The prepreg constituting each layer is laminated with the direction of each reinforcing fiber being shifted from the angle with respect to the prepreg constituting the other layer of the laminate. When the prepreg laminate has four layers, one reference line is taken, and the angle between the direction of the reinforcing fiber of each layer and the reference line (the one with the smaller absolute value) is defined as θ. It is preferable to laminate with = 45 °, 45 °, 45 °, and −45 °. Moreover, when the laminated body of prepreg is 8 layers, it is preferable to laminate | stack in order with (theta) = 0 degree, 90 degrees, -45 degrees, 45 degrees, 45 degrees, -45 degrees, 90 degrees, 0 degrees. When each layer of the prepreg laminate is configured as described above, the prepreg laminate and the honeycomb core are not warped, and the mechanical strength anisotropy is eliminated.

  A laminate of prepregs is obtained by stacking a predetermined number of prepregs, heating and melting the cycloolefin polymer with a hot press machine, a molding machine, or the like, and bringing the layers into close contact with each other. The heating temperature is usually in the range of 100 to 180 ° C, preferably 120 to 170 ° C, more preferably 140 to 160 ° C. The heating time is usually in the range of 1 to 30 minutes, preferably 2 to 20 minutes, more preferably 5 to 15 minutes. When the heating temperature and time are within this range, the crosslinking reaction does not proceed and the adhesion between layers is improved.

The thickness of the prepreg used in the present invention is appropriately selected according to the purpose of use, but is usually 0.03 to 0.50 mm, preferably 0.05 to 0.30 mm, more preferably 0.10 to 0. The range is 20 mm. When the thickness of the prepreg is within this range, the shapeability at the time of lamination and the properties such as mechanical strength and toughness of the honeycomb core obtained by crosslinking are sufficiently exhibited, which is preferable.
The amount of the volatile component of the prepreg used in the present invention is an amount that volatilizes in one hour at 200 ° C., and is usually 5% by weight or less, preferably 3% by weight or less, more preferably 1% by weight or less. If the amount of volatile components in the prepreg, such as unreacted monomers, is excessive, stickiness of the prepreg occurs, resulting in poor operability, and voids are generated in the honeycomb core after crosslinking, resulting in decreased mechanical strength or bleeding. There is a risk that problems such as heat resistance decrease will occur. Such a prepreg with a small amount of volatile components and a small amount of voids can be easily obtained by the bulk polymerization method. In a wet method in which a reinforcing fiber is impregnated with a polymer solution and dried to obtain a prepreg, both volatile components and voids may remain in large amounts. In addition, a large amount of voids may remain even in a hot melt method in which a polymer is heated and melted to impregnate reinforcing fibers to obtain a prepreg.

(Honeycomb core)
In the honeycomb core of the present invention, the prepreg or the prepreg laminate is formed into a corrugated shape, and the obtained plurality of corrugated shaped products are stacked while being shifted by a half pitch. After joining, it can be easily obtained by cross-linking as desired. When the reinforcing fiber to be used is a unidirectional material, a reference line is set so as to be orthogonal to the opening end face of the honeycomb core obtained as shown in FIG. 1, and the direction in which the reinforcing fiber faces as described above, The corrugated shaped product is manufactured while adjusting the angle θ formed with the reference line.
The corrugated shape has a cross-sectional shape formed in a wave shape, and examples of the shape include a wave shape, an uneven shape, and a V shape. FIG. 2 shows an example of a corrugated shaped product obtained by the present invention.
As a method of forming into a corrugated shape, a conventional method may be used. For example, a method of installing a prepreg or a prepreg laminate in a corrugated mold and heating and bending, a corrugated roll, or a press Examples include a method of forming by supplying a prepreg to a machine and heating and pressing. The heating temperature and time depend on the lamination conditions of the prepreg laminate.
As a method of joining the corrugated molded product, a method of applying an adhesive to the ridges and valleys of the corrugated molded product shown in FIG. A method of melting and joining the crests and troughs of the corrugated molded product that are stacked by using a chain transfer agent as the constituent component and lowering the melt viscosity at the time of heating can be mentioned.

  In the present invention, it is preferable to laminate the molded product via an adhesive because the mechanical strength of the honeycomb core can be improved to a high degree. As the adhesive used in the present invention, those generally used can be used without particular limitation, and examples thereof include epoxy resin-based, polyurethane-based, acrylic-based, and rubber-based adhesives.

  In the present invention, the honeycomb core can be obtained by bonding the corrugated molded product as described above and crosslinking the cycloolefin polymer. The cycloolefin polymer in the honeycomb core has a crosslinked structure and does not dissolve in the solvent. Such a solvent is appropriately selected from solvents such as aromatic hydrocarbons such as benzene and toluene; ethers such as diethyl ether and tetrahydrofuran; halogenated hydrocarbons such as dichloromethane and chloroform.

  As a method of crosslinking the cycloolefin polymer, a conventional method may be used, and the above-described mold, autoclave, hot press machine, oven, and the like can be used. The heating temperature is equal to or higher than the temperature at which a crosslinking reaction is induced by the crosslinking agent, and typically ranges from 100 to 300 ° C, preferably from 150 to 250 ° C. For example, when a radical generator is used as the cross-linking agent, it is at least 1 minute half-life temperature of the radical generator, preferably at least 5 ° C. higher than the 1-minute half-life temperature, more preferably 10 ° C. above the 1-minute half-life temperature. This is a high temperature. The heating time is usually in the range of 0.1 to 120 minutes, preferably 1 to 60 minutes, more preferably 2 to 20 minutes. The pressure is usually 0.01 to 1 MPa, preferably 0.05 to 0.5 MPa. Further, the hot pressing may be performed in a vacuum or a reduced pressure atmosphere. When the heating temperature, time, and pressure are within this range, the adhesion between the corrugated shaped articles is improved.

  The honeycomb core of the present invention thus obtained is lightweight and excellent in mechanical strength. For example, it is used for sports such as golf shafts and fishing rods, such as OA and AV equipment, automobile and railway vehicle components, aircraft interior parts, and the like. It is suitably used for other general industrial applications. Specific applications include, for example, fishing rods, golf club shafts, tennis rackets, ski stocks, and other sports applications; displays, FDD carriages, chassis, HDD, MO, motor brush holders, parabolic antennas, laptop computers, mobile phones, Electric / electronic devices such as digital still cameras, PDAs, portable MDs, liquid crystal displays, plasma displays; telephones, facsimiles, VTRs, photocopiers, televisions, irons, hair dryers, rice cookers, microwave ovens, audio equipment, vacuum cleaners, toiletries Supplies, leather discs, compact discs, lighting, refrigerators, air conditioners, typewriters, word processors, office automation equipment and household appliances; undercovers, scuff plates, pillar trims, professionals Automobiles such as rubber shafts, drive shafts, wheels, wheel covers, fenders, door mirrors, room mirrors, feshers, bumpers, bumper beams, bonnets, trunk hoods, aero parts, platforms, cowl louvers, roofs, instrument panels, spirals and various modules Parts; aircraft parts such as landing gear pods, wing reds, spoilers, edges, ladders, and failings; and building materials such as panels. Among these, it is particularly suitable as a member for vehicles such as automobiles and airplanes.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited to these Examples. In the examples and comparative examples, “part” and “%” are based on weight unless otherwise specified.

Each characteristic in an Example and a comparative example is measured and evaluated according to the following method.
(1) Mechanical strength: The obtained honeycomb core was allowed to stand for 24 hours in a constant temperature and humidity chamber kept constant at a temperature of 25 ° C. and a humidity of 55%, and the mechanical strength (shear strength) before and after standing was determined as MIL. -Measured in the W direction of FIG. 3 based on STD-401, and the rate of decrease is determined according to the following criteria.
○: Decreasing rate of less than 20% ×: Decreasing rate of 20% or more (2) Productivity: The time required for the process of heating the prepreg is judged according to the following criteria.
○: Less than 90 minutes Δ: 90 minutes or more, less than 180 minutes ×: 180 minutes or more

Example 1
A catalyst solution is prepared by dissolving 51 parts of benzylidene (1,3-dimesityl-4-imidazolidin-2-ylidene) (tricyclohexylphosphine) ruthenium dichloride and 79 parts of triphenylphosphine in 952 parts of toluene. Separately, 100 parts of dicyclopentadiene (DCP), 0.74 part of allyl methacrylate as a chain transfer agent, 1.2 parts of di-t-butyl peroxide (a 1 minute half-life temperature of 186 ° C.), a crosslinking aid A monomer solution is prepared by mixing 15 parts of trimethylolpropane trimethacrylate as an agent and 1.0 part of 3,5-di-t-butyl-4-hydroxyanisole as a phenolic antioxidant. The above catalyst solution is added at a rate of 0.12 ml per 100 g of cycloolefin monomer and stirred to prepare a polymerizable composition.
Next, 100 parts of the resulting polymerizable composition was cast on a polyethylene naphthalate film (thickness 75 μm), and carbon fiber pyrofil TR 30S 3L (manufactured by Mitsubishi Rayon Co., Ltd.) aligned in one direction on the polyethylene naphthalate film. Further, 80 parts of the above polymerizable composition is cast thereon, and further covered with a polyethylene naphthalate film, and a carbon fiber is impregnated with the polymerizable composition using a roller. Subsequently, a prepreg having a thickness of 125 μm is obtained by heating at 130 ° C. for 1 minute in an inert oven. By stacking the four prepregs obtained so that the carbon fibers of each layer are θ = −45 ° / 45 ° / 45 ° / −45 ° in order from the bottom, and heat-pressing at 150 ° C. for 5 minutes at 3 MPa. To obtain a prepreg laminate. Next, the obtained prepreg laminate is placed in an uneven mold. Here, the orientation of the prepreg laminate is such that the direction of θ = 0 ° (reference line when a unidirectional material is used for reinforcing fibers) as shown in FIG. 1 is orthogonal to the opening end face of the obtained honeycomb core. In the mold, the honeycomb core cells after joining became hexagonal and the cell pitch (shown in FIG. 4) by heating and pressing at a temperature of 6 ° C./min, 220 ° C. for 15 minutes, and 3 MPa. A corrugated shaped product having a length of one cell) of 3/8 inch is obtained (FIG. 2). Next, an adhesive denatite (manufactured by Nagase ChemteX Corporation) is applied to the peaks and valleys of the corrugated molded product. This is shifted by a half pitch for each sheet, and 5 sheets are stacked so that the wave crest portion shown in FIG. 2 is bonded to the adjacent prepreg valley portion, and at 0.1 MPa and 180 ° C. with a heating press. A honeycomb core is obtained by thermocompression bonding for 15 minutes. The obtained honeycomb core is immersed in chloroform, and after being left at room temperature for 30 minutes, there is no change in weight, and it is confirmed that sufficient crosslinking occurs in the cycloolefin polymer. The evaluation results are shown in Table 1.

(Comparative Example 1)
As epoxy resins, 30 parts of EP-828 (liquid bisphenol A type; manufactured by Japan Epoxy Resin Co., Ltd.), 10 parts of EPC-152 (brominated; manufactured by Asahi Kasei Co., Ltd.), and YD-170 (liquid bisphenol F type; manufactured by Toto Kasei Co., Ltd.) ) 10 parts and 20 parts of 4,4′-diaminodiphenylsulfone as a curing agent are mixed to obtain a polymerizable composition. The obtained polymerizable composition is impregnated into carbon fiber pyrofil TR 30S 3L (manufactured by Mitsubishi Rayon Co., Ltd.) arranged in one direction, and dried in an oven at 100 ° C. for 10 minutes to obtain a prepreg. Thereafter, the conditions for obtaining a laminate of prepregs were set to 3 MPa at 120 ° C. for 5 minutes, and the conditions for obtaining a corrugated shaped product were set to 3 ° C./minute for temperature rise and 60 minutes for 150 ° C. Similarly, a honeycomb core is obtained. The obtained honeycomb core is immersed in chloroform, and after standing for 30 minutes at room temperature, there is no change in weight, and it is confirmed that sufficient crosslinking has occurred. The evaluation results are shown in Table 1.

(Comparative Example 2)
A 250 μm prepreg is obtained in the same manner as in Comparative Example 1 except that carbon fiber woven pyrofil TR 3110M (manufactured by Mitsubishi Rayon Co., Ltd.) is used as the reinforcing fiber. The obtained two prepreg polyethylene naphthalate films are peeled off, the prepregs are overlapped, and heated at 100 ° C. for 5 minutes at 3 MPa to obtain a laminate of prepregs.
Thereafter, a honeycomb core is obtained in the same manner as in Comparative Example 1. The obtained honeycomb core is immersed in chloroform, and after standing for 30 minutes at room temperature, there is no change in weight, and it is confirmed that sufficient crosslinking has occurred. The evaluation results are shown in Table 1.

In this invention, it is a figure which shows the relationship between the reference line when using a unidirectional material for a reinforced fiber ((theta) = 0 degree), and the structure of a corrugated molded object. It is a figure which shows the position of the peak and trough of the corrugated shaped product obtained by this invention. It is a figure of an example of the honeycomb core obtained by this invention. The concept of the cell pitch in the honeycomb core obtained by the present invention is illustrated in an easy-to-understand manner.

Claims (4)

  A step of impregnating a reinforcing fiber with a polymerizable composition comprising a cycloolefin monomer and a polymerization catalyst, followed by polymerization to produce a prepreg, forming a prepreg into a corrugated shape, and obtaining a molded product A method for manufacturing a honeycomb core, comprising: stacking and cross-linking the formed products.   The method for manufacturing a honeycomb core according to claim 1, wherein the polymerizable composition further contains a crosslinking agent.   The method for manufacturing a honeycomb core according to claim 1 or 2, wherein the reinforcing fibers are reinforcing fibers arranged in one direction.   The method for manufacturing a honeycomb core according to any one of claims 1 to 3, wherein the reinforcing fibers are carbon fibers.

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