JP2009209211A - Cyclic phosphorous based flame retardant-containing prepreg, and layered product using the prepreg - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a prepreg capable of manufacturing a layered product attaining non-halogen flame retardancy using a conjugated diene polymer such as polybutadiene and polyisoprene having a high Q value, and a layered product using the prepreg. <P>SOLUTION: The layered product is manufactured by using the prepreg in which a reinforced fiber is impregnated with a curable resin composition containing a conjugated diene polymer, a curing agent, a filling agent and a cyclic phosphorous flame retardant having a cyclic structure and having a phosphorous atom in the cyclic structure, and curing the prepreg after the mutual prepregs are layered or it is layered with other materials. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a prepreg suitable for a multilayer wiring board including an electronic circuit wiring board, and a laminate using the prepreg.

  A circuit board is generally composed of a dielectric layer and a conductor layer. In recent years, with the advent of advanced information era, information transmission has started to move to higher speeds and higher frequencies, and microwave communication and millimeter wave communication have become a reality. In these high frequency era circuit boards, it is necessary to reduce noise and transmission loss at high frequencies to the limit, and selection of a dielectric material having a high Q value and formation of a smooth conductor layer have become important issues.

  As for the dielectric material, an epoxy resin having a Q value of usually about 10 to 30 has been used in a conventional low-frequency (K to MHz region) circuit board. However, in a high-frequency circuit board in the GHz range, if the Q value is small, the performance and reliability of the circuit board are not sufficient, and several times to 10 times or more than the conventional Q value, specifically, the Q value is 100 or more. The material is preferably 200 or more, more preferably 300 or more, and so-called non-halogen flame retardant which does not contain halogen and has flame retardancy is demanded.

  As dielectric materials having a high Q value, conjugated diene polymers such as polybutadiene and polyisoprene are attracting attention. For example, Patent Document 1 discloses a thermoplastic block copolymer such as 1,2-polybutadiene having a molecular weight of less than 5,000 at room temperature and a solid polymer such as styrene-butadiene-styrene triblock polymer, dicumyl peroxide and t- Organic peroxides (curing agents) such as butylperoxyhexine-3, crosslinking agents such as divinylbenzene and polyfunctional acrylates, bromine such as ethylenebistetrabromophthalimide, tetradecabromodiphenoxybenzene and decabromodiphenoxyl oxide A flame retardant, a filler such as silica or titania, and a silane coupling agent are mixed and impregnated into a fiber reinforcing material as a slurry, and then the solvent is removed to prepare a prepreg, and then a plurality of sheets between two copper foils Laminates made by laminating and curing prepregs are disclosed. .

  Patent Document 2 includes a thermosetting composition containing polybutadiene or polyisoprene in a proportion of 25 to 50% by volume of the whole, a woven fabric containing 10 to 40% by volume of the whole, and A wiring board material comprising a granular filler contained in a ratio of 5 to 60% by volume per whole, a free radical curing initiator, and a flame retardant is disclosed, and a bromine-containing flame retardant is described as the flame retardant. ing.

  Patent Document 3 discloses an electric circuit material containing polybutadiene and polyisoprene, ethylene-propylene rubber having a weight average molecular weight of less than 50,000, a flame retardant, a knitted fabric, a granular filler, and a peroxide curing agent. Examples of the flame retardant include bromides such as ethylenebistetrabromophthalimide, tetradecabromodiphenoxybenzene, and decabromodiphenoxyl oxide. However, these flame retardant technologies are based on bromides, and non-halo flame retardants have been desired for consumer use.

  On the other hand, Patent Document 4 discloses a flame retardant resin composition containing, as essential components, a crosslinking (auxiliary) agent such as polyphenylene ether resin and triallyl isocyanurate, a phosphorus compound that functions as a flame retardant, and a silicone compound. Yes. Furthermore, radical generators such as perbutyl P and peroximon F-40 (trade name) that promote crosslinking of polyphenylene ether and triallyl isocyanurate may be used, and cyclic phosphorus compounds as phosphorus compounds that function as flame retardants That the flame retardant resin composition is impregnated into a porous substrate and then heated to produce a prepreg, and specific examples include 60 parts by mass of polyphenylene ether and triallyl isocyanurate as a crosslinking (auxiliary) agent. A flame retardant composition comprising 46 parts by weight, 18 parts by weight of a phosphinic acid ester, 15 parts by weight of a silicone compound and 4 parts by weight of a reaction accelerator is described. However, this publication is a flame retardant technology for a resin, which is a polyphenylene ether-based resin containing a polar group such as an ether bond in a basic structural unit and having an aromatic ring, and is excellent in flame retardancy. The technical field is different from the flame retardancy of polymers close to rubber called polymers.

JP-A-8-208856 JP-A-10-117052 Special table 2003-528450 gazette JP 2005-225913 A

  An object of the present invention is to provide a prepreg capable of producing a laminate capable of non-halogen flame retardant using a conjugated diene polymer such as polybutadiene or polyisoprene having a high Q value, and a laminate using the prepreg. is there.

  As a result of intensive studies in view of the above problems, the present inventor has found that a curable composition containing a conjugated diene polymer such as 1,2-polybutadiene or a conjugated diene polymer such as a styrene-butadiene-styrene block copolymer, a crosslinking agent, and a filler. A specific cyclic phosphorus flame retardant is added to the composition and impregnated into a reinforcing fiber to produce a prepreg, and then the prepreg is laminated with the same prepreg or with other materials and cured by hot press to obtain a laminate property. And found that a laminate excellent in flame retardancy can be obtained. In addition, by setting the ratio of the filler and the cyclic phosphorus flame retardant in the curable resin composition within a specific range, the characteristics of the Q value and the non-halo flame retardant can be highly balanced, and the curable resin composition It has been found that when a siloxane compound is further added to the product, the non-halo flame retardancy is highly enhanced. The present inventor has completed the present invention based on these findings.

Thus, according to the present invention, a reinforcing fiber is impregnated with a curable resin composition containing a conjugated diene polymer, a curing agent, a filler, and a cyclic phosphorus-based flame retardant having a ring structure and a phosphorus atom in the ring structure. A prepreg is provided.
According to the present invention, there is also provided a laminate obtained by curing the prepreg described above after laminating the prepregs with each other or with other materials.

  According to the present invention, using a polybutadiene or polyisoprene having a high Q value, it is possible to easily produce a laminate excellent in laminateability and non-halo flame retardancy and a prepreg that provides the laminate. Moreover, since the laminate of the present invention is excellent in laminateability and non-halo flame retardancy, it can be suitably used for high-frequency circuit boards such as microwaves or millimeter waves for communication equipment applications.

(Conjugated diene polymer)
The conjugated diene polymer used in the present invention is not particularly limited as long as it contains at least a conjugated diene unit, but at least one selected from the group consisting of a conjugated diene homopolymer and a conjugated diene copolymer is preferable. Used for. These polymerization modes are appropriately selected according to the purpose of use and can be carried out according to a conventional method.

  Examples of the conjugated diene include butadiene, isoprene, chloroprene, pentadiene and the like, preferably butadiene and isoprene, and more preferably butadiene.

  Examples of the conjugated diene homopolymer include polybutadiene, polyisoprene, polychloroprene, polycyanobutadiene, polypentadiene, and the like, preferably polybutadiene, polyisoprene, and more preferably polybutadiene.

  The conjugated diene copolymer is not particularly limited as long as it is a copolymer containing at least a conjugated diene unit. For example, a random copolymer or a block copolymer can be used.

  Examples of the monomer copolymerizable with the conjugated diene in the conjugated diene copolymer include cyano group-containing vinyl, amino group-containing vinyl, pyridyl group-containing vinyl, alkoxyl group-containing vinyl, and aromatic vinyl. Of these, cyano group-containing vinyl and aromatic vinyl are preferable, and aromatic vinyl is particularly preferable.

  Examples of the aromatic vinyl include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2,4-diisopropylstyrene, 2,4-dimethylstyrene, and 4-t-butylstyrene. , 5-t-butyl-2-methylstyrene, N, N-dimethylaminoethylstyrene, N, N-diethylaminoethylstyrene, etc., among which styrene and α-methylstyrene are particularly preferable.

  The ratio of the conjugated diene unit of the conjugated diene copolymer and the copolymerizable monomer unit is appropriately selected according to the purpose of use, and is usually 95/5 to 5 by weight ratio of conjugated diene unit / copolymerizable monomer unit. 5/95, preferably 90/10 to 10/90, more preferably 80/20 to 20/80, and characteristics within this range such as operability, mechanical strength and toughness of the prepreg and laminate Is highly balanced and suitable.

  The bonding mode of the conjugated diene block copolymer is appropriately selected according to the purpose of use, such as a 2-block copolymer, a 3-block copolymer, a 4-block copolymer, and a 5-block copolymer. A polymer is preferred because it can maintain a high balance between the laminateability and mechanical strength of the prepreg and laminate. Specific examples include styrene-butadiene-styrene block polymers, styrene-isoprene-styrene block polymers, α-methylstyrene-butadiene-α-methylstyrene block polymers, and preferably styrene-butazine-styrene block polymers.

  The vinyl bond amount of the conjugated diene part of the conjugated diene polymer used in the present invention is appropriately selected according to the purpose of use, but it is determined using a Hampton method (R. Hampton, Anal. Chem., Using an infrared spectrophotometer). 21, 923 (1949)), usually 5 mol%, preferably 40 mol% or more, more preferably 60 mol% or more, most preferably 80 mol% or more. When the 1,2-vinyl bond amount is in this range, the mechanical strength and heat resistance of the laminate can be highly improved, which is preferable.

  The molecular weight of the conjugated diene polymer used in the present invention can be appropriately selected according to the purpose of use, but it is a weight average molecular weight measured by gel permeation chromatography (polystyrene equivalent toluene eluent), usually 500 to 5,000. In the range of 1,000 to 1,000,000.

  In the present invention, each of the conjugated diene polymers can be used alone or in combination of two or more. By combining a conjugated diene homopolymer and a conjugated diene copolymer, the operability of the prepreg and the laminate machine It is preferable because characteristics such as mechanical properties and toughness can be highly balanced. When the conjugated diene homopolymer and the conjugated diene copolymer are combined, the molecular weight of the conjugated diene homopolymer is a weight average molecular weight measured by gel permeation chromatography (polystyrene equivalent toluene eluent) and is usually 500 to 500,000. The range is preferably 1,000 to 10,000, more preferably 1,000 to 5,000. When combined, the molecular weight of the conjugated diene copolymer is a weight average molecular weight measured by gel permeation chromatography (polystyrene equivalent toluene eluent) and is usually 1,000 to 1,000,000, preferably 5,000. It is -500,000, More preferably, it is the range of 10,000-300,000. When the molecular weights of the conjugated diene homopolymer and the conjugated diene copolymer are within this range, the relationship between the laminate property of the laminate and the mechanical strength is highly balanced, which is preferable.

  The ratio in the case of combining the conjugated diene homopolymer and the conjugated diene copolymer is appropriately selected according to the purpose of use, but is usually 90/10 to 5 / in the weight ratio of the conjugated diene homopolymer / conjugated diene copolymer. 95, preferably in the range of 50/50 to 10/90, more preferably in the range of 30/70 to 15/85. When the ratio between the two is in this range, characteristics such as mechanical properties, toughness and dielectric properties of the laminate are highly balanced, which is preferable.

(Curing agent)
The curing agent used in the present invention is not particularly limited as long as it can crosslink the conjugated diene polymer, but a radical generator is usually used. Examples of the radical generator include organic peroxides, diazo compounds, and nonpolar radical generators, with organic peroxides and nonpolar radical generators being preferred. In particular, a non-polar radical generator is suitable for increasing the Q value.

  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. Of these, dialkyl peroxides and peroxyketals are preferable.

  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 curing agent used in the present invention is a radical generator, the one-minute half-life temperature is appropriately selected depending on the type and use conditions of the radical generator, but is usually 50 to 350 ° C, preferably 100 to 250 ° C. More preferably, it is the range of 150-230 degreeC. Here, the half-life temperature for 1 minute is a temperature at which half of the radical generator decomposes in 1 minute. For example, it is 186 ° C. for di-t-butyl peroxide and 194 ° C. for 2,5-dimethyl-2,5-bis (t-butylperoxy) -3-hexyne.

  These curing agents can be used alone or in combination of two or more. The amount of the curing agent used is usually 0.01 to 10 parts by weight, preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the conjugated diene polymer. .

(Cyclic phosphorus flame retardant)
The cyclic phosphorus-based flame retardant used in the present invention is a compound having a ring structure and having a phosphorus atom in the ring structure. For example, a cyclic phosphoric acid compound, a cyclic phosphonic acid compound, a cyclic phosphinic acid compound and the like can be mentioned, and a cyclic phosphinic acid compound is preferable.

  Examples of the cyclic phosphinic acid compound include 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 8-t-butyl-9,10-dihydro-9-oxa-10-phosphaphenanthrene. -10 oxide, 10- (2,5-dihydroxyphenyl) -10H-9-oxa-10-phosphaphenanthrene-10-oxide, 10- (2,3-dihydroxyphenyl) -10H-9-oxa 10-phos Examples include phenanthrene-10-oxide, 10- (2,4-dihydroxyphenyl) -10H-9-oxa-10-oxide, and the like.

  These cyclic phosphorus flame retardants can be used alone or in combination of two or more. The blending amount is appropriately selected according to the purpose of use, but is usually 10 to 500 parts by weight, preferably 20 to 200 parts by weight, more preferably 50 to 100 parts by weight with respect to 100 parts by weight of the conjugated diene polymer. It is a range.

(filler)
The filler used in the present invention is not particularly limited as long as it is generally used industrially, and any of inorganic fillers and organic fillers can be used. is there.

  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, and oxidation. Inorganic oxide particles such as titanium, iron oxide, zinc oxide, magnesium oxide, tin oxide, beryllium oxide, barium ferrite and strontium ferrite; inorganic carbonate particles such as calcium carbonate, magnesium carbonate and sodium hydrogen carbonate; inorganic such as calcium sulfate 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, nitriding Aluminum, silicon carbide particles and Isuka, and the like. Among these, metal particles, inorganic oxide particles, inorganic hydroxide particles, inorganic silicate particles, titanate particles, and the like are preferable in order to highly balance the dielectric loss tangent and laminate property of the laminate. Oxide particles and titanates are more preferred.

  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, various elastomers, and waste plastics.

  These fillers can be used alone or in combination of two or more, and the blending amount is usually 10 to 1,000 parts by weight, preferably 50 to 100 parts by weight with respect to 100 parts by weight of the conjugated diene polymer. It is in the range of 750 parts by weight, more preferably 100 to 500 parts by weight.

  The ratio of the filler and the cyclic phosphorus flame retardant is appropriately selected according to the purpose of use, but is usually 1/9 to 9/1, preferably 1/9, by weight ratio of the cyclic phosphorus flame retardant / filler. When it is in the range of ˜7 / 3, more preferably 1/9 to 5/5, and most preferably 2/8 to 4/6, the characteristics of dielectric loss and flame retardancy are highly balanced and suitable.

(Curable resin composition)
The curable resin composition used in the present invention contains the conjugated diene polymer, the curing agent, the cyclic phosphorus flame retardant, and the filler as essential components, and if necessary, a siloxane compound, an anti-aging agent, and a curing aid. And other compounding agents can be added.

  In the present invention, it is preferable to add a siloxane compound to the curable resin composition so that the non-halo flame retardancy can be highly enhanced. A siloxane compound is a compound having a siloxane skeleton. Specifically, low molecular silicones, silicone oligomers, silicone polymers, and the like can be used. In particular, siloxane compounds having an aromatic ring-containing siloxane skeleton (low molecular silicones, silicone oils, silicone polymers, etc.) are preferable.

  These siloxane compounds can be used alone or in combination of two or more, and the amount used is usually 1 to 100 parts by weight, preferably 5 to 50 parts by weight, based on 100 parts by weight of the conjugated diene polymer. Parts, more preferably in the range of 10 to 40 parts by weight.

  In the present invention, when a siloxane compound is added to the curable resin composition, the total amount of the siloxane compound, the cyclic phosphorus-based flame retardant and the filler is preferably 50 parts by weight or more with respect to 100 parts by weight of the conjugated diene polymer. More preferably 50 to 1,500 parts by weight, still more preferably 100 to 1,000 parts by weight, particularly preferably 200 to 600 parts by weight, the properties of lamination and non-halo flame retardant are highly balanced It is preferable. The proportions of the cyclic phosphorus flame retardant, the filler and the siloxane compound are appropriately selected according to the purpose of use, but are usually 1/9 by weight ratio of (siloxane compound + cyclic phosphoric acid flame retardant) / filler. ~ 9/1, preferably 1/9 to 7/3, more preferably 1/9 to 5/5, most preferably 2/8 to 4/6, with dielectric loss and flame retardancy The characteristics are highly balanced and suitable.

  As an anti-aging agent, a curing reaction is achieved by adding at least one anti-aging agent selected from the group consisting of a phenol-based anti-aging agent, an amine-based anti-aging agent, a phosphorus-based anti-aging agent and a sulfur-based anti-aging agent. The oxidation-resistant deterioration resistance of the obtained fiber-reinforced composite material can be improved to a high degree without hindering the above, 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 amount of the antioxidant used is appropriately selected depending on 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 conjugated diene polymer. Is in the range of 0.01 to 1 part by weight.

  Examples of other compounding agents include other flame retardants, colorants, dyes, and pigments. Other flame retardants include phosphorus-containing flame retardants other than the above-mentioned cyclic phosphorus flame retardants, nitrogen-containing flame retardants, halogen-containing flame retardants, metal hydroxide flame retardants such as aluminum hydroxide, antimony compounds such as antimony trioxide, etc. Is mentioned. 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 additives can be used alone or in combination of two or more, and the amount used is appropriately selected within a range not impairing the effects of the present invention.

  The curable composition used for this invention can be obtained by mixing the said component. As a mixing method, it can carry out in accordance with a conventional method.

(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 fibers and glass fibers are preferable, and aramid fibers, liquid crystal polyester fibers, and glass fibers are particularly preferable. As the glass fiber, fibers such as E glass, NE glass, S glass, D glass, and H glass can be suitably used.

  These reinforcing fibers can be used alone or in combination of two or more. The amount of reinforcing fibers used is appropriately selected according to the purpose of use, but is usually in the range of 10 to 90% by weight, preferably 20 to 80% by weight, more preferably 30 to 70% by weight in the prepreg or laminate. In this range, the dielectric loss tangent and mechanical strength of the laminate are highly balanced, which is preferable.

(Prepreg)
The prepreg of the present invention can be produced by impregnating the curable resin composition into the reinforcing fiber.

  As an impregnation method, a conventional method may be followed. For example, a conjugated diene polymer, a cross-linking agent, a cyclic phosphorus compound, a filler, a curing agent, and other compounding agents as required may be dissolved in a solvent to lower the viscosity. Wet method in which reinforced fiber is impregnated and then desolvated, curable resin composition is coated on release paper, reinforced fiber is aligned on it, and heat-dissolved resin is pressure impregnated with a roll or doctor blade. Thereafter, there is a hot melt method (dry method) for allowing to cool, but usually a wet method is performed.

  The drying temperature after impregnation by the wet method is usually in the range of 50 to 250 ° C., preferably 100 to 200 ° C., more preferably 120 to 170 ° C. In particular, when the crosslinking agent is a radical generator, The temperature is usually 1 minute half-life temperature or less, preferably 10 minutes or less of 1-minute half-life temperature, more preferably 20 minutes or less of 1-minute half-life temperature or less. The drying time may be appropriately selected, but is usually in the range of 0.1 to 120 minutes, preferably 0.5 to 60 minutes, more preferably 1 to 20 minutes. Heating the curable resin composition in this range of temperature and time is preferable because a prepreg with less unreacted monomer can be obtained.

  Although the thickness of the prepreg of this invention is suitably selected according to a use purpose, it is 0.001-10 mm normally, Preferably it is 0.01-1 mm, More preferably, it is the range of 0.05-0.5 mm. When it is within this range, the operability of the prepreg and the mechanical strength and toughness characteristics of the laminate obtained by curing are sufficiently exhibited, which is preferable.

  The amount of volatile components of the prepreg of the present invention is the amount that volatilizes when heated at 200 ° C. for 1 hour, and is usually 30% by weight or less, preferably 10% by weight or less, more preferably 5% by weight or less, most preferably 1% % Or less. If the amount of volatile components in the prepreg is excessively large, stickiness of the prepreg will occur and the operability and storage stability will deteriorate, and voids will occur in the cured laminate, reducing the appearance and mechanical strength, and bleeding. Problems such as heat resistance and chemical resistance are undesirable.

(Laminate)
The laminated body of the present invention is obtained by curing the above prepreg between the same prepregs or with other materials and shaping as necessary. Other materials that may be laminated are appropriately selected according to the purpose of use, and examples thereof include thermoplastic resin materials and metal materials, and metal materials are particularly preferably used. As a metal material, what is generally used with a circuit board can be used without a special restriction | limiting, Usually, metal foil, Preferably copper foil is used. Although the thickness of a metal material is suitably selected according to the intended purpose, it is 1-50 micrometers normally, Preferably it is 3-30 micrometers, More preferably, it is 5-20 micrometers, Most preferably, it is the range of 5-15 micrometers.

  The lamination and curing method may be in accordance with a conventional method, for example, using a known press machine having a press frame mold for flat plate molding, a press molding machine such as a sheet mold compound (SMC) or a bulk mold compound (BMC). Can be hot-pressed. The heating temperature is a temperature at which crosslinking with a curing agent occurs, and is usually at least 1 minute half-life temperature, preferably at least 5 ° C. above the 1-minute half-life temperature, more preferably at least 10 ° C. above the 1-minute half-life temperature. Temperature. Usually, it is 100-300 degreeC, Preferably it is the range of 150-250 degreeC. The heating time is in the range of 0.1 to 180 minutes, preferably 1 to 120 minutes, more preferably 2 to 20 minutes. As a press pressure, it is 0.1-20 MPa normally, Preferably it is 0.1-10 MPa, More preferably, it is 1-5 MPa. Further, the hot pressing may be performed in a vacuum or a reduced pressure atmosphere.

  The laminate of the present invention thus obtained can be suitably used as a high-frequency substrate material in a wide range because it has little transmission loss in the high-frequency region and is imparted with non-halo flame retardancy.

  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 was measured and evaluated according to the following method.
(1) Laminating property: The appearance of the obtained fiber reinforced composite material laminate was observed and evaluated according to the following criteria.
A: No separation between layers, no deformation of shape is observed. B: Separation between layers, a deformation of shape is observed, but slight.
X: Exfoliation between layers, shape collapse, etc. are severely observed (2) Flame retardance: A 0.9 mm thick laminate is cut out as a 125 mm x 15 mm test piece, and the flame is brought close to 10 cm below and left for 10 seconds After that, the flame was released and the subsequent burning was observed and evaluated according to the following criteria.
(Double-circle): There is no flaming after flare-off.
○: Although there is a flaming after taking off the flame, it disappears soon.
X: The flame after flare reached the upper part and burned violently.

Example 1
100 parts of polybutadiene resin B3000 (manufactured by Nippon Soda Co., Ltd .; molecular weight 3000, 1,2-vinyl bond content 95 mol%), 20 parts of styrene-butadiene-styrene block polymer (Tufrene manufactured by Asahi Kasei Co., Ltd.), 9,10-dihydro as a flame retardant 80 parts of -9-oxa-10-phosphaphenanthrene-10-oxide, 35 parts of silica (manufactured by Admafine, average particle size 0.5 μm), 1.2 parts of di-t-butyl peroxide were mixed in xylene, A curable composition was obtained. Next, the obtained polymerizable composition was impregnated into glass cloth (E glass), and the solvent was removed by heating to prepare a prepreg. The reinforcing fiber content of the prepreg was 41%.

  Next, 5 sheets of the prepared prepreg sheets were stacked, and heated and pressed at 200 ° C. for 10 minutes at 3 MPa to obtain a laminate. The laminate properties and flame retardancy of the obtained laminate were evaluated, and the results are shown in Table 1.

Example 2
Example 1 was repeated except that the amount of flame retardant 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was changed to 60 parts, and the amount of filler silica was changed to 100 parts. A laminate was obtained. The laminate properties and flame retardancy of the obtained laminate were evaluated, and the results are shown in Table 1. Moreover, when the dielectric loss tangent of the obtained laminated body was measured, it turned out that it is smaller than the dielectric loss tangent of the laminated body obtained in Example 1, and preferable.

Example 3
The amount of flame retardant 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is changed to 40 parts, and 20 parts of DC4-7081 (manufactured by Dow Corning Toray) is newly added as a silicone compound. Except that, a laminate was obtained in the same manner as in Example 1. The laminate properties and flame retardancy of the obtained laminate were evaluated, and the results are shown in Table 1. Moreover, when the dielectric loss tangent of the obtained laminated body was measured, it turned out that it is still smaller than the dielectric loss tangent of the laminated body obtained in Example 2.

Comparative Example 1
A laminate was obtained in the same manner as in Example 1 except that ammonium polyphosphate was used as a flame retardant. The properties of the obtained laminate were evaluated and the results are shown in Table 1.

Comparative Example 2
A laminate was obtained in the same manner as in Example 1 except that the flame retardant was eliminated and the silica was changed to 150 parts. The properties were evaluated, and the results are summarized in Table 1.

Comparative Example 3
Except using 100 parts of silicone compounds instead of silica, it carried out similarly to the comparative example 1, and obtained the laminated body, evaluated each characteristic, and put together the result in Table 1.

Claims (5)

A prepreg formed by impregnating reinforcing fibers with a curable resin composition containing a conjugated diene polymer, a curing agent, a filler, and a cyclic phosphorus-based flame retardant having a ring structure and a phosphorus atom in the ring structure. The prepreg according to claim 1, wherein the ratio of the cyclic phosphorus flame retardant to the filler is in the range of 1/9 to 9/1 in terms of the weight ratio of the cyclic phosphorus flame retardant / filler. The prepreg according to claim 1 or 2, wherein the curable resin composition further contains a siloxane compound. The prepreg according to claim 3, wherein the total amount of the filler, the cyclic phosphorus-based flame retardant and the siloxane compound is 50 parts by weight or more with respect to 100 parts by weight of the conjugated diene polymer. A laminate obtained by curing the prepreg according to any one of claims 1 to 4 between the prepregs or after being laminated with another material.