JP2023042918A - Production method of semi-cured composite, method for producing cured composite, and semi-cured composite - Google Patents

Abstract

To suppress a rapid rise in the viscosity of a semi-cured material in a semi-cured composite in which a porous material is impregnated with a semi-cured material of a curable composition.SOLUTION: An aspect of the present invention provides a method for producing a semi-cured composite, comprising the steps of: impregnating a porous body with a curable composition containing a first polymerizable component, a first polymerization initiator for initiating the polymerization of the first polymerizable component, a second polymerizable component, and a second polymerization initiator for initiating the polymerization of the second polymerizable component under conditions different from those of the first polymerization initiator; and polymerizing the first polymerizable component with the first polymerization initiator.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a method for producing a semi-cured composite, a method for producing a cured composite, and a semi-cured composite.

Electronic parts such as LED lighting devices and in-vehicle power modules face the problem of efficiently dissipating heat generated during use. To solve this problem, a method of increasing the thermal conductivity of an insulating layer of a printed wiring board on which electronic components are mounted, and a method of attaching an electronic component or a printed wiring board to a heat sink via an electrically insulating thermal interface material. etc. are being taken. A composite (radiation member) composed of a resin and a ceramic such as boron nitride is used for such an insulating layer and thermal interface material.

WO2014/196496

Since the composite as described above is used by adhering it to an adherend such as an electronic component, it is desirable that the state of high adhesiveness can be maintained for a long time because of excellent handleability. In the composite, when the resin is in a semi-cured state and within a predetermined viscosity range, excellent adhesiveness is achieved. In conventional composites, it was difficult to keep the viscosity within the desired range because the viscosity of the semi-cured resin tended to increase rapidly.

An object of one aspect of the present invention is to suppress a rapid increase in the viscosity of the semi-cured product in a semi-cured composite in which a porous body is impregnated with a semi-cured product of a curable composition.

The present inventors contain a first polymerizable component and a second polymerizable component as polymerizable components, and contain a polymerization initiator that initiates the polymerization of each polymerizable component under conditions different from each other. It has been found that the use of the curable composition makes it difficult for the viscosity of the semi-cured product of the curable composition to rise sharply in a desired viscosity range (for example, a viscosity range in which adhesion is excellent).

One aspect of the present invention provides a first polymerizable component, a first polymerization initiator that initiates polymerization of the first polymerizable component, a second polymerizable component, and a first polymerization initiator. a step of impregnating the porous body with a curable composition containing a second polymerization initiator that initiates polymerization of the second polymerizable component under different conditions; and a step of polymerizing with a polymerization initiator.

Another aspect of the present invention includes a first polymerizable component, a first polymerization initiator that initiates polymerization of the first polymerizable component, a second polymerizable component, and a first polymerization initiator A step of impregnating the porous body with a curable composition containing a second polymerization initiator that initiates polymerization of the second polymerizable component under conditions different from the first polymerizable component, A cured product composite comprising a step of polymerizing with a first polymerization initiator, and a step of polymerizing a second polymerizable component with a second polymerization initiator after polymerizing the first polymerizable component. to provide a method of manufacturing

Another aspect of the present invention is a semi-cured composite comprising a porous body and a semi-cured curable composition impregnated in the porous body, wherein the curable composition is a first a polymerizable component, a first polymerization initiator for initiating polymerization of the first polymerizable component, a second polymerizable component, and a second polymerizable component under conditions different from those of the first polymerization initiator; and a second polymerization initiator that initiates polymerization, and the semi-cured product contains the polymer of the first polymerizable component, the second polymerizable component, and the second polymerization initiator. , to provide a semi-cured composite.

In the production method and semi-cured composite described above, the first polymerizable component may contain at least one selected from the group consisting of maleimide compounds, cyanate compounds, and silicone compounds. Moreover, the porous body may have an average pore diameter of 1 μm or more and a porosity of 30% by volume or more.

In the above semi-cured composite, part of the first polymerizable component may remain in the semi-cured composite.

According to one aspect of the present invention, in a semi-cured composite in which a porous body is impregnated with a semi-cured material of a curable composition, a rapid increase in the viscosity of the semi-cured material can be suppressed.

It is a graph which shows an example of the viscosity behavior of a curable composition.

Embodiments of the present invention will be described below. However, the present invention is not limited to the following embodiments.

As used herein, "(meth)acryl" means acryl or methacryl corresponding thereto, and similar expressions such as "(meth)acrylate" are also used.

<Method for producing semi-cured composite and semi-cured composite>
A method for producing a semi-cured composite according to one embodiment comprises a first polymerizable component, a first polymerization initiator that initiates polymerization of the first polymerizable component, a second polymerizable component, A step of impregnating a porous body with a curable composition containing a second polymerization initiator that initiates polymerization of the second polymerizable component under conditions different from the first polymerization initiator (hereinafter referred to as impregnation and a step of polymerizing the first polymerizable component with a first polymerization initiator (hereinafter also referred to as a semi-curing step) S2.

In the impregnation step S1, first, a porous body is prepared. A porous body has a structure in which a plurality of fine pores (hereinafter also referred to as “pores”) are formed. At least some of the pores in the porous body may be connected to each other to form continuous pores.

The porous body may be made of an inorganic compound, preferably a sintered body of an inorganic compound. The sintered body of an inorganic compound may be a sintered body of an insulator. The insulator in the insulator sintered body preferably contains non-oxides such as carbide, nitride, diamond and graphite, and more preferably contains nitride. The carbide may be silicon carbide or the like. The nitride may contain at least one nitride selected from the group consisting of boron nitride, aluminum nitride and silicon nitride, preferably boron nitride. That is, the porous body may preferably be formed of a sintered body of an insulator containing boron nitride, more preferably a sintered body of boron nitride. When the porous body is formed of a boron nitride sintered body, the boron nitride sintered body may be formed by sintering together primary particles of boron nitride. As boron nitride, both amorphous boron nitride and hexagonal boron nitride can be used.

The thermal conductivity of the porous body may be, for example, 30 W/(m·K) or more, 50 W/(m·K) or more, or 60 W/(m·K) or more. When the porous material is made of an inorganic compound having excellent thermal conductivity, the heat resistance of the resulting semi-cured composite can be reduced. The thermal conductivity of the porous body is measured by a laser flash method on a sample of the porous body having a length of 10 mm, a width of 10 mm and a thickness of 1 mm.

The average pore diameter of the pores in the porous body may be, for example, 0.1 μm or more, 0.3 μm or more, or 0.5 μm or more, and the curable composition described later in the pores is preferably 0.6 μm or more, more preferably 0.8 μm or more, and still more preferably 1 μm or more, from the viewpoint of being able to fill the . The average pore diameter of the pores is preferably 5.0 μm or less, 4.0 μm or less, 3.5 μm or less, 3.0 μm or less, 2.5 μm or less, 2 0 μm or less, or 1.5 μm or less.

The average pore diameter of the pores in the porous body is the pore diameter distribution (horizontal axis: pore diameter, vertical axis: cumulative pore volume) measured using a mercury porosimeter, and the cumulative pore volume is the total pore volume. Defined as the pore size reaching 50%. As the mercury porosimeter, for example, a mercury porosimeter manufactured by Shimadzu Corporation can be used, and the pressure is increased from 0.03 atmosphere to 4000 atmospheres for measurement.

The ratio of pores in the porous body (porosity) is preferably 10% by volume or more, 20% by volume or more, or 30% by volume or more, preferably 70% by volume or less, more preferably 60% by volume or less, from the viewpoint of improving the insulation and thermal conductivity of the semi-cured composite , more preferably 60% by volume or less, particularly preferably 50% by volume or less. The ratio (porosity) is determined by the bulk density D1 (g/cm ³ ) obtained from the volume and mass of the porous body and the theoretical density D2 of the material constituting the porous body (for example, 2.28 g/ cm ³ ), the following formula:
Porosity (volume%) = [1-(D1/D2)] × 100
Calculated according to

In this embodiment, at least two polymerizable components are used. For this reason, it may be difficult for one of the polymerizable components (for example, the polymerizable component whose polymerization reaction starts first) to impregnate the porous body. , it is preferable to use a porous body that is easily impregnated. If the average pore diameter or porosity is small, it becomes difficult for the polymerizable component to impregnate. Also in this embodiment using , the porous body can be more appropriately impregnated with the polymerizable component. From the viewpoint of achieving both impregnability and heat dissipation, it is more preferable to use a porous body having an average pore diameter of 1 to 5 μm and a porosity of 30 to 65% by volume.

The porous body may be produced by sintering raw materials, or a commercially available product may be used. When the porous body is a sintered body of an inorganic compound, the porous body can be obtained by sintering powder containing the inorganic compound. That is, in one embodiment, the impregnation step S1 includes a step of sintering a powder containing an inorganic compound (hereinafter also referred to as an inorganic compound powder) to obtain a sintered body of the inorganic compound, which is a porous body.

A sintered body of an inorganic compound may be prepared by subjecting a slurry containing a powder of an inorganic compound to a spheroidizing treatment using a spray dryer or the like, further molding the sintered body, and then sintering the sintered body to prepare a porous sintered body. The molding method is not particularly limited, and for example, a sheet-like molding may be formed by a doctor blade method. Press molding may be performed using a mold to obtain a compact, a mold may be used, or a cold isostatic pressing (CIP) method may be used.

A sintering aid may be used during sintering. The sintering aid may be, for example, yttria oxide, oxides of rare earth elements such as alumina oxide and magnesium oxide, alkali metal carbonates such as lithium carbonate and sodium carbonate, and boric acid. When a sintering aid is added, the amount of the sintering aid added is, for example, 0.01 parts by mass or more, or 0.1 parts by mass with respect to a total of 100 parts by mass of the inorganic compound and the sintering aid. or more. The amount of the sintering aid added may be 20 parts by mass or less, 15 parts by mass or less, or 10 parts by mass or less with respect to a total of 100 parts by mass of the inorganic compound and the sintering aid. By setting the addition amount of the sintering aid within the above range, it becomes easy to adjust the average pore diameter of the sintered body (porous body) within the above range.

The sintering temperature of the inorganic compound may be, for example, 1600° C. or higher, or 1700° C. or higher. The sintering temperature of the inorganic compound may be, for example, 2200° C. or lower, or 2000° C. or lower. The sintering time of the inorganic compound may be, for example, 1 hour or more and 30 hours or less. The atmosphere during sintering may be, for example, an inert gas atmosphere such as nitrogen, helium, and argon.

For sintering, for example, a batch type furnace, a continuous type furnace, or the like can be used. Batch type furnaces include, for example, muffle furnaces, tubular furnaces, atmosphere furnaces, and the like. Examples of continuous furnaces include rotary kilns, screw conveyor furnaces, tunnel furnaces, belt furnaces, pusher furnaces, and koto-shaped continuous furnaces.

The porous body may be formed by cutting or the like into a desired shape and thickness before the impregnation step S1, if necessary.

In the impregnation step S1, subsequently, a solution containing a curable composition is prepared in an impregnation device, and the porous body is immersed in the solution to impregnate the pores of the porous body with the curable composition.

The curable composition contains, as polymerizable components, a first polymerizable component and a second polymerizable component. The first polymerizable component and the second polymerizable component may be components polymerizable by a thermal polymerization initiator. That is, the curable composition may be a thermosetting composition. The first polymerizable component and the second polymerizable component may be the same or different.

The polymerizable components used as the first polymerizable component and the second polymerizable component are not particularly limited as long as they are components that can be generally used in curable compositions. These polymerizable components include, for example, epoxy compounds, (meth) acrylic compounds, oxetane compounds, vinyl compounds, phenol compounds, maleimide compounds, cyanate compounds, and at least one selected from the group consisting of silicone compounds. good.

Examples of epoxy compounds include bifunctional epoxy resins such as bisphenol A type epoxy resins, bisphenol F type epoxy resins, and bisphenol A/F type epoxy resins; novolak type epoxy resins such as phenol novolak type epoxy resins and cresol novolak type epoxy resins; Polyfunctional epoxy resins such as phenolmethane type epoxy resins; Glycidylamine type epoxy resins such as N,N-diglycidylaniline and N,N-diglycidyl-o-toluidine; Heterocyclic ring-containing epoxy resins such as triglycidyl isocyanurate; Alicyclic epoxy resins such as bisphenol A-type epoxy resins and hydrogenated bisphenol F-type epoxy resins; aromatic ring-containing epoxy resins such as 1,6-bis(2,3-epoxypropan-1-yloxy)naphthalene; dicyclo So-called epoxy resins such as pentadiene type epoxy resins can be mentioned. An epoxy compound may be used individually by 1 type or in combination of 2 or more types.

The (meth)acrylic compound may be a monofunctional (meth)acrylate having one (meth)acryloyl group, or may be a polyfunctional (meth)acrylate having two or more (meth)acryloyl groups.

Monofunctional (meth)acrylates include (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2 - ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate , 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, glycidyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate , phenylglycidyl (meth)acrylate, dimethylaminomethyl (meth)acrylate, phenylcellosolve (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, biphenyl (meth)acrylate, 2-hydroxy Ethyl (meth)acryloyl phosphate, phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxypropyl (meth)acrylate, benzyl (meth)acrylate and the like.

Polyfunctional (meth)acrylates include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, nonaethylene glycol di(meth)acrylate. , 1,3-butylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, dimethyloltricyclodecane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, neopentyl glycol di( meth)acrylate, 1,6-hexamethylene di(meth)acrylate, hydroxypivalic acid ester neopentyl glycol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetraacrylate , dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tris(meth)acryloxyethyl isocyanurate and the like.

As the (meth)acrylic compound, the compounds shown above may be used singly or in combination of two or more.

The oxetane compounds include 3-ethyl-3-hydroxymethyloxetane, 3-ethyl-3-{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane, 1,4-bis{[(3-ethyl -3-oxetanyl)methoxy]methyl}benzene, 4,4′-bis[(3-ethyl-3-oxetanyl)methoxymethyl]biphenyl, 1,4-benzenedicarboxylate bis[(3-ethyl-3-oxetanyl) ] methyl ester, 3-ethyl-3-(phenoxymethyl)oxetane, 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane, di[1-ethyl(3-oxetanyl)]methyl ether, 3-ethyl- 3-{[3-(triethoxysilyl)propoxy]methyl}oxetane, oxetanylsilsesquioxane, phenol novolac oxetane and the like. The oxetane compounds may be used singly or in combination of two or more.

Examples of vinyl compounds include ethyl vinyl ether, propyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexanedimethanol monovinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, and isopropenyl. ether-propylene carbonate, dodecyl vinyl ether, diethylene glycol monovinyl ether, octadecyl vinyl ether, hydroxyethyl vinyl ether, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, butanediol divinyl ether, Vinyl ether group-containing compounds such as hexanediol divinyl ether, cyclohexanedimethanol divinyl ether, and trimethylolpropane trivinyl ether; styrene compounds such as styrene, methylstyrene, and ethylstyrene; A vinyl compound may be used individually by 1 type or in combination of 2 or more types.

Phenol compounds include phenol novolak resin, alkylphenol borak resin, bisphenol A novolak resin, dicyclopentadiene type phenol resin, Xylok type phenol resin, terpene-modified phenol resin, polyvinylphenols, bisphenol F, bisphenol S type phenol resin, poly So-called phenolic resins such as p-hydroxystyrene, condensates of naphthol and aldehydes, and condensates of dihydroxynaphthalene and aldehydes. Phenol compounds may be used alone or in combination of two or more.

Maleimide compounds include 4,4′-diphenylmethanebismaleimide, polyphenylmethanemaleimide, m-phenylenebismaleimide, 2,2′-bis[4-(4-maleimidophenoxy)phenyl]propane, 3,3′-dimethyl -5,5′-diethyl-4,4′-diphenylmethanebismaleimide, 4-methyl-1,3-phenylenebismaleimide, 4,4′-diphenyletherbismaleimide, 4,4′-diphenylsulfonebismaleimide, 1, 3-bis(3-maleimidophenoxy)benzene, 1,3-bis(4-maleimidophenoxy)benzene and the like. These maleimide compounds may be used singly or in combination of two or more.

Examples of cyanate compounds include novolac type cyanate resins; bisphenol type cyanate resins such as bisphenol A type cyanate resins, bisphenol E type cyanate resins, and tetramethylbisphenol F type cyanate resins; Naphthol aralkyl type cyanate resins; dicyclopentadiene type cyanate resins; and biphenylene skeleton-containing phenol aralkyl type cyanate resins. A cyanate compound may be used individually by 1 type or in combination of 2 or more types.

The silicone compound (also referred to as silicone resin) may be a millable silicone, preferably an addition reaction silicone. The addition-reactive silicone may be an addition-reactive liquid silicone. Specific examples of addition reaction type liquid silicones include one-component reaction type organopolysiloxanes having both vinyl groups and H—Si groups in one molecule, or organopolysiloxanes having vinyl groups at terminals or side chains. Examples include two-liquid silicone with organopolysiloxane having two or more H—Si groups at the terminal or side chain.

From the viewpoint of reaction control and safety during semi-curing, the first polymerizable component is preferably at least one selected from the group consisting of epoxy compounds, (meth)acrylic compounds, maleimide compounds, cyanate compounds and silicone compounds. It contains a seed, more preferably at least one selected from the group consisting of an epoxy compound, a maleimide compound and a cyanate compound, and may contain an epoxy compound and a maleimide compound.

The second polymerizable component contains at least one selected from the group consisting of epoxy compounds, (meth)acrylic compounds, vinyl compounds, maleimide compounds, cyanate compounds and silicone compounds, more preferably epoxy compounds and vinyl compounds. and at least one selected from the group consisting of maleimide compounds, and may contain an epoxy compound, a vinyl compound and a maleimide compound.

The combination of the first polymerizable component and the second polymerizable component may be the following combination from the viewpoint that the semi-cured product can be more preferably maintained within the desired viscosity range.
(1) The first polymerizable component contains a cyanate compound, and the second polymerizable component contains an epoxy compound, a vinyl compound and a maleimide compound.
(2) The first polymerizable component contains an epoxy compound and a maleimide compound, and the second polymerizable component contains an epoxy compound.
As with the cyanate compound and the epoxy compound in (1) above, the first polymerizable component may be a combination that also functions as a curing agent for the second polymerizable component. The same applies to the second polymerizable component.

The content of the first polymerizable component is preferably 5% by mass or more, more preferably 8% by mass or more, based on the total amount of the curable composition, from the viewpoint of facilitating handling of the semi-cured composite. It is preferably 10% by mass or more, and may be 20% by mass or more or 30% by mass or more. The content of the first polymerizable component is preferably 51% by mass or less, more preferably 40% by mass or less, based on the total amount of the curable composition, from the viewpoint that the adhesiveness and adhesion of the semi-cured product are suitable. , more preferably 30% by mass or less.

The content of the second polymerizable component is preferably 49% by mass or more, more preferably 60% by mass or more, more preferably 60% by mass or more, based on the total amount of the curable composition, from the viewpoint that the adhesion of the semi-cured product is suitable. is 70% by mass or more. The content of the second polymerizable component is preferably 95% by mass or less, more preferably 92% by mass or less, based on the total amount of the curable composition, from the viewpoint of facilitating handling of the semi-cured composite. Preferably, it is 90% by mass or less.

The mass ratio of the content of the first polymerizable component to the content of the second polymerizable component in the curable composition (first polymerizable component/second polymerizable component) is 0.1 or more. , 0.15 or more, 0.2 or more, 0.25 or more, or 0.4 or more, and 1.5 or less, 1 or less, 0.7 or less, 0.5 or less, or 0.3 or less It's okay.

The curable composition comprises a first polymerization initiator (curing agent) that initiates polymerization of the first polymerizable component, and a second polymerization initiator that initiates polymerization of the second polymerizable component under conditions different from those of the first polymerization initiator. and a second polymerization initiator (curing agent) that causes the

Each of the first polymerization initiator and the second polymerization initiator may be at least one selected from the group consisting of radical polymerization initiators, cationic polymerization initiators, and anionic polymerization initiators. The radical polymerization initiator, cationic polymerization initiator, and anionic polymerization initiator may be thermal radical polymerization initiators, thermal cationic polymerization initiators, and thermal anionic polymerization initiators, respectively. The curable composition may further contain a polymerization initiation aid that assists the functions of the first polymerization initiator and the second polymerization initiator.

The radical polymerization initiator is preferably a compound (thermal radical polymerization initiator) that generates radicals upon heating to initiate a chain polymerization reaction. Examples of the radical polymerization initiator include organic peroxides, azo compounds, benzoin compounds, benzoin ether compounds, acetophenone compounds, benzopinacol and the like, and benzopinacol is preferably used. As the radical polymerization initiator, these compounds may be used alone or in combination of two or more.

Examples of organic peroxides include ketone peroxides such as methyl ethyl ketone peroxide, cyclohexanone peroxide, and methyl cyclohexanone peroxide; 1,1-bis(t-butylperoxy)cyclohexane, 1,1-bis(t-butylperoxy )-2-methylcyclohexane, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-hexylperoxy)cyclohexane, 1,1-bis(t -hexylperoxy)-peroxyketals such as 3,3,5-trimethylcyclohexane; hydroperoxides such as p-menthane hydroperoxide; α,α'-bis(t-butylperoxy)diisopropylbenzene, dicumyl dialkyl peroxide such as peroxide, t-butyl cumyl peroxide, di-t-butyl peroxide; diacyl peroxide such as octanoyl peroxide, lauroyl peroxide, stearyl peroxide, benzoyl peroxide; bis(4-t -butyl cyclohexyl) peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-3-methoxybutyl peroxycarbonate; t-butyl peroxy pivalate, t-hexyl peroxypivalate, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, 2,5-dimethyl-2,5-bis(2-ethylhexanoyl per oxy)hexane, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-hexylperoxyisopropylmonocarbonate, t- Butyl peroxy-3,5,5-trimethylhexanoate, t-butyl peroxylaurylate, t-butyl peroxy isopropyl monocarbonate, t-butyl peroxy-2-ethylhexyl monocarbonate, t-butyl peroxybenzoate , t-hexylperoxybenzoate, 2,5-dimethyl-2,5-bis(benzoylperoxy)hexane, and peroxyesters such as t-butylperoxyacetate.

Organic peroxides include Kayamec RTMA, M, R, L, LH, SP-30C, Perkadox CH-50L, BC-FF, Kadox B-40ES, Perkadox 14, Trigonox RTM22-70E, 23-C70, 121, 121-50E, 121-LS50E, 21-LS50E, 42, 42LS, Kayaester RTMP-70, TMPO-70, CND-C70, OO-50E, AN, Kayabutyl RTMB, Parkadox 16, Kayacarbon RTMBIC-75, AIC-75 (manufactured by Kayaku Nourion Co., Ltd.); Permek RTMN, H, S, F, D, G, Perhexa RTMH, HC, TMH, C, V, 22, MC, Purcure RTMAH, AL, HB, Perbutyl Commercially available products such as RTMH, C, ND, L, Permil RTMH, D, Perroyl RTMIB, IPP, and Perocta RTMND (manufactured by NOF Corporation) may also be used.

Azo compounds include 2,2′-azobisisobutyronitrile, 2,2′-azobis(2,4-dimethylvaleronitrile), 2,2′-azobis(4-methoxy-2′-dimethylvaleronitrile ) and the like.

As the azo compound, commercially available products such as VA-044, V-70, VPE-0201 and VSP-1001 (manufactured by Wako Pure Chemical Industries, Ltd.) may be used.

The radical polymerization initiator is preferably at least one selected from the group consisting of diacyl peroxides, peroxy esters and azo compounds, from the viewpoint of curability and heat resistance of the semi-cured product.

The radical polymerization initiator may be uniformly dispersed by reducing the particle size. The average particle size of the radical polymerization initiator is preferably 5 μm or less, more preferably 3 μm or less, from the viewpoint of appropriately using the semi-cured composite for various purposes. Although the lower limit of the average particle size of the radical polymerization initiator is not limited, it is, for example, 0.1 μm or more. The average particle size of the radical polymerization initiator can be measured with a laser diffraction/scattering particle size distribution analyzer (dry type) (for example, LMS-30 manufactured by Seishin Enterprise Co., Ltd.).

The cationic polymerization initiator is not particularly limited as long as it generates cationic species such as Bronsted acids and Lewis acids. Cationic polymerization initiators include, for example, sulfonium salts, phosphonium salts, quaternary ammonium salts, aryldiazonium salts, organic metal salts, allene-ion complexes, boron trifluoride amine complexes and the like. The use of such a cationic polymerization initiator tends to improve the dimensional accuracy and degree of cure. As the cationic polymerization initiator, these compounds may be used singly or in combination of two or more.

Examples of sulfonium salts include San-Aid SI-L85, SI-L110, SI-L145, SI-L160, SI-H15, SI-H20, SI-H25, SI-H40, SI-H50, SI-60L, SI- Commercial products such as 80L, SI-100L, SI-80, SI-100 (manufactured by Sanshin Chemical Industry Co., Ltd.) and CP-77 (manufactured by ADEKA Corporation) can be used.

Phosphonium salts include benzyl-4-hydroxyphenylmethylsulfonium hexafluoroantimonate, benzyl-4-hydroxyphenylmethylsulfonium hexafluorophosphate, 4-acetoxyphenylbenzylmethylsulfonium hexafluoroantimonate, 4-acetoxyphenyldimethylsulfonium hexafluoro antimonate, benzyl-4-methoxyphenylmethylsulfonium hexafluoroantimonate, benzyl-2-methyl-4-hydroxyphenylmethylsulfonium hexafluoroantimonate, benzyl-3-chloro-4-hydroxyphenylmethylsulfonium hexafluoroarsenate, benzyl-3-methyl-4-hydroxy-5-tert-butylphenylmethylsulfonium hexafluoroantimonate, 4-methoxybenzyl-4-hydroxyphenylmethylsulfonium hexafluoroantimonate, dibenzyl-4-hydroxyphenylsulfonium hexafluoroantimonate, Dibenzyl-4-hydroxyphenylsulfonium hexafluorophosphate, 4-acetoxyphenyldibenzylsulfonium hexafluoroantimonate, dibenzyl-4-methoxyphenylsulfonium hexafluoroantimonate, nitrobenzyl-4-hydroxyphenylmethylsulfonium hexafluoroantimonate, 3 ,5-dinitrobenzyl-4-hydroxyphenylmethylsulfonium hexafluoroantimonate, β-naphthylmethyl-4-hydroxyphenylmethylsulfonium hexafluoroantimonate and the like.

As the quaternary ammonium salt, commercially available products such as CXC-1616 (manufactured by KING INDUSTRY) can be used.

Examples of organic metal salts include organic salts such as bis(2,4-pentanedionato) zinc (II), zinc octylate, zinc naphthenate, cobalt naphthenate, copper naphthenate, iron acetylacetonate, nickel octylate, and manganese octylate. metal salts.

As the anionic polymerization initiator, a known one that can be used as an anionic polymerization initiator for the polymerizable component can be employed. The anionic polymerization initiator may be, for example, a thermal anionic polymerization initiator that generates a base capable of anionically polymerizing the anionically polymerizable compound by heat. More specifically, the anionic polymerization initiator includes known aliphatic amine compounds, aromatic amine compounds, secondary or tertiary amine compounds, imidazole compounds, polymercaptan compounds, boron trifluoride-amine complexes, dicyandiamide, Organic acid hydrazides and the like can be used, and encapsulated imidazole compounds that exhibit good latency against temperature can also be preferably used.

A phenol-based polymerization initiator (curing agent) can also be used as the anionic polymerization initiator. A phenol-based polymerization initiator may have a plurality of phenolic hydroxyl groups. Examples of the phenol-based polymerization initiator include phenolic resins such as novolac-type phenolic resins and resol-type phenolic resins. etc. A phenol-based polymerization initiator can be particularly preferably used as the first polymerization initiator when the first polymerizable component is a cyanate compound.

With regard to the second polymerization initiator, "initiating the polymerization of the second polymerizable component under conditions different from those of the first polymerization initiator" means that a polymerization initiator of a type different from that of the first polymerization initiator is used. By use is meant to initiate the polymerization of the second polymerizable component under different conditions than the first polymerization initiator. In order to make the types of polymerization initiators different between the first polymerization initiator and the second polymerization initiator, for example, the first polymerization initiator is a radical polymerization initiator and the second polymerization initiator is The agent may be a cationic polymerization initiator, or may be some other combination. Alternatively, by selecting a polymerization initiator having a reaction initiation temperature different from that of the first polymerization initiator as the second polymerization initiator, the types of the polymerization initiators may be different from each other. By selecting a polymerization initiator that is less reactive than the first polymerization initiator as the agent, the types of the polymerization initiators may be different from each other. The ease of reaction of the polymerization initiator can be determined, for example, by the strength of the nucleophilicity of the catalyst, the magnitude of the electron-donating property of the ligand, the molecular weight, and the like.

The reaction initiation temperature of the polymerization initiator was measured using a differential scanning calorimeter (DSC) at a temperature elevation rate of 10°C/min. can be confirmed by reacting with a polymerization initiator.

When a polymerization initiator having a reaction initiation temperature different from that of the first polymerization initiator is selected as the second polymerization initiator, the reaction initiation temperature of the second polymerization initiator and the reaction initiation temperature of the first polymerization initiator are (the reaction initiation temperature of the second polymerization initiator - the reaction initiation temperature of the first polymerization initiator) is preferably 20°C or higher, more preferably 40°C or higher, and still more preferably 60°C or higher. The upper limit of the difference is not particularly limited, and can be appropriately set according to the heating temperature for obtaining a cured composite (details will be described later). When the difference between the reaction initiation temperature of the second polymerization initiator and the reaction initiation temperature of the first polymerization initiator is 20° C. or more, the polymerization of the second polymerizable component is initiated in the semi-curing step S2. It can be suppressed.

The content of the first polymerization initiator, based on the total amount of the curable composition, may be 0.005% by mass or more, 0.01% by mass or more, or 0.1% by mass or more, and 5% by mass or less , 3% by mass or less, or 1% by mass or less.

The content of the second polymerization initiator, based on the total amount of the curable composition, may be 0.005% by mass or more, 0.01% by mass or more, or 0.5% by mass or more, and 10% by mass or less , 5% by mass or less, or 3% by mass or less.

The curable composition may further contain other components in addition to the above-described first polymerizable component, second polymerizable component, first polymerization initiator, and second polymerization initiator. . Other components include, for example, silane coupling agents, surface treatment agents, adhesion imparting agents, antioxidants, and additives for inhibiting polymerization inhibition (phosphorus compounds, thiol compounds, etc.). The total content of other components may be 10% by mass or less, 5% by mass or less, or 3% by mass or less based on the total amount of the curable composition.

The impregnation step S1 may be performed under reduced pressure conditions or under increased pressure conditions, or may be performed in combination with impregnation under reduced pressure conditions and impregnation under increased pressure conditions. The pressure in the impregnation device when the impregnation step S1 is performed under reduced pressure conditions may be, for example, 1000 Pa or less, 500 Pa or less, 100 Pa or less, 50 Pa or less, or 20 Pa or less. The pressure in the impregnation device when the impregnation step S1 is performed under pressurized conditions may be, for example, 1 MPa or higher, 3 MPa or higher, 10 MPa or higher, or 30 MPa or higher.

The curable composition may be heated when the porous body is impregnated with the curable composition. By heating the curable composition, the viscosity of the solution is adjusted and impregnation into the porous body is promoted. The temperature for heating the curable composition for impregnation can be appropriately set, but may be a temperature exceeding the reaction initiation temperature of the first polymerization initiator, and the reaction initiation temperature of the second polymerization initiator. may be lower than The upper limit of the temperature for heating the curable composition may be equal to or lower than the reaction initiation temperature of the first polymerization initiator +20°C.

In the impregnation step S1, the porous body is immersed in the solution containing the curable composition and held for a predetermined time. The predetermined time (immersion time) is not particularly limited, and may be, for example, 5 minutes or longer, 30 minutes or longer, 1 hour or longer, 5 hours or longer, 10 hours or longer, 100 hours or longer, or 150 hours or longer.

In the semi-curing step S2, the first polymerizable component in the curable composition is polymerized with the first polymerization initiator. When the first polymerization initiator is a thermal polymerization initiator, the porous body impregnated with the curable composition is heated at a temperature at which the first polymerization initiator reacts (hereinafter also referred to as temperature T1). can polymerize the first polymerizable component.

The temperature T1 is preferably 70° C. or higher, more preferably 80° C. or higher, and still more preferably 90° C. or higher, from the viewpoint of sufficiently impregnating the semi-cured material into the porous body. The temperature T1 is preferably 180° C. or lower, more preferably 150° C. or lower, and even more preferably 120° C. or lower, from the viewpoint of reducing the change in viscosity over time. The temperature T1 refers to the atmospheric temperature when heating the porous body impregnated with the curable composition.

The heating time in the semi-curing step S2 may be 1 hour or longer, 3 hours or longer, or 5 hours or longer, and may be 12 hours or shorter, 10 hours or shorter, or 8 hours or shorter.

A semi-cured composite can be produced by the steps described above. That is, a semi-cured composite according to one embodiment includes the porous body described above and the semi-cured material of the curable composition impregnated in the porous body.

The proportion of the porous material in the semi-cured composite is preferably 30% by volume or more based on the total volume of the semi-cured composite, from the viewpoint of improving the insulation and thermal conductivity of the semi-cured composite. , more preferably 40% by volume or more, and still more preferably 50% by volume or more. The proportion of the porous material in the semi-cured composite is, for example, 90% by volume or less, 80% by volume or less, 70% by volume or less, or 60% by volume or less based on the total volume of the semi-cured composite. you can

The semi-cured product contains a polymer of the first polymerizable component, a second polymerizable component, and a second polymerization initiator. That is, it can be said that the semi-cured product contains a polymer of the first polymerizable component and an unpolymerized product of the second polymerizable component.

The semi-cured product comprises a polymer of an epoxy compound, a polymer of a (meth)acrylic compound, a polymer of a maleimide compound, a polymer of a cyanate compound, and a polymer of a silicone compound as the polymer of the first polymerizable component. may contain at least one selected from the group, and may contain at least one selected from the group consisting of a polymer of an epoxy compound, a polymer of a maleimide compound, and a polymer of a cyanate compound; and may contain a polymer of a maleimide compound. It can be confirmed by FT-IR and NMR that the semi-cured product contains these polymers.

The semi-cured product may not contain the first polymerizable component (all of the first polymerizable component may be polymerized), and the semi-cured product may contain one of the first polymerizable components. The moieties may be included without polymerization. That is, in the semi-cured composite according to one embodiment, part of the first polymerizable component remains in the semi-cured composite as a minor component. By intentionally allowing a part of the first polymerizable component to remain in the semi-cured composite as a minor component, it is possible to suppress the initiation of polymerization of the second polymerizable component in the semi-curing step S2. .

The fact that the semi-cured product contains a part of the first polymerizable component can be confirmed by analyzing the semi-cured product composite using FT-IR or NMR and determining the functional group contained in the first polymerizable component. It can be confirmed by analysis. At this time, a solvent such as acetone may be used to extract and concentrate the first polymerizable component before analysis. Alternatively, the decomposition product of the semi-cured composite is analyzed using pyrolysis gas chromatography to confirm that the semi-cured composite contains part of the first polymerizable component. can be done.

When the semi-cured product contains the first polymerizable component, its content is less than the second polymerizable component. The content of the first polymerizable component contained in the semi-cured product is 5 parts by mass or less with respect to a total of 100 parts by mass of the content of the first polymerizable component and the content of the second polymerizable component. , 3 parts by mass or less, or 1 part by mass or less, or 0.5 mass % or more. The content is determined by analyzing the semi-cured composite by FT-IR to examine the types of functional groups possessed by the first polymerizable component and the second polymerizable component, and then by NMR to determine the structure of the functional group, and by checking the ratio of the peaks obtained.

Since this semi-cured composite contains the second polymerizable component in an unpolymerized state, it is superior in adhesion to an adherend as compared with a cured product in which the curable composition is completely cured. In addition, this semi-cured composite can easily maintain a desired viscosity for excellent adhesion to adherends unless the second polymerizable component is polymerized. Thereby, a semi-cured composite having excellent handleability can be obtained.

The semi-cured composite can be used by forming it into a sheet or the like and adhering it to an adherend. For example, by obtaining a semi-cured composite by the method described above, removing the resin (curable composition or semi-cured product) attached to the outer periphery of the composite, and cutting it into a predetermined thickness, semi-cured The composite can be formed into sheets. The sheet-shaped semi-cured composite is placed on an adherend and pressed while being heated at the reaction temperature of the second polymerization initiator, for example, to attach the semi-cured composite to the adherend. The semi-cured material can be cured while being adhered to form a cured material composite (details will be described later).

<Method for producing cured composite and cured composite>
By polymerizing the second polymerizable component of the semi-cured composite described above, a cured composite can be produced. That is, the method for producing a cured product composite according to one embodiment includes a first polymerizable component, a first polymerization initiator that initiates polymerization of the first polymerizable component, and a second polymerizable component. and a second polymerization initiator that initiates polymerization of the second polymerizable component under conditions different from those of the first polymerization initiator, impregnating the porous body with a curable composition (impregnation step) S1, a step of polymerizing the first polymerizable component with the first polymerization initiator (semi-curing step) S2, and after polymerizing the first polymerizable component, the second polymerizable component is and a step (curing step) S3 of polymerizing with the second polymerization initiator. Specific aspects of the impregnation step S1 and the semi-curing step S2 are as described above.

In the curing step S3, the second polymerizable component in the semi-cured product is polymerized with the second polymerization initiator. When the second polymerization initiator is a thermal polymerization initiator, the porous body impregnated with the curable composition is heated at a temperature at which the second polymerization initiator reacts (hereinafter also referred to as temperature T2). can polymerize the second polymerizable component.

From the viewpoint of polymerizing the second polymerizable component in a short time, the temperature T2 is preferably 150° C. or higher, more preferably 180° C. or higher, and even more preferably 200° C. or higher. The temperature T2 is preferably 260° C. or lower, more preferably 240° C. or lower, and still more preferably 220° C. or lower from the viewpoint of volatilization of low molecular weight components contained in the curable composition and thermal stability of the composition. The temperature T2 refers to the ambient temperature when heating the semi-cured composite.

The heating time at temperature T2 may be 1 hour or more, 5 hours or more, or 10 hours or more, and may be 30 hours or less, 25 hours or less, or 20 hours or less.

An example of the viscosity behavior of the curable composition in such a method for producing a cured composite is shown in FIG. FIG. 1 shows an example in which the first polymerization initiator and the second polymerization initiator are thermal polymerization initiators. As shown in FIG. 1, in the semi-curing step S2, the first polymerizable component is polymerized by heating, and the viscosity of the curable composition increases as the polymerization progresses over time. Then, when most of the polymerization of the first polymerizable component is completed, the viscosity of the curable composition becomes substantially constant within a specific range. Specifically, in the viscosity range of 10 ² to 10 ⁶ Pa s, it is preferable that there is no time region where the viscosity increase per hour is 200000 Pa s or more, and the viscosity increase per hour is 110000 Pa s or more. It is more preferable that there is no time region where the viscosity rises to 50000 Pa·s or more per hour. Subsequently, in the curing step S3, first, the viscosity of the curable composition is reduced due to the viscosity reduction (softening) of the second polymerizable component by heating, and then the second polymerizable component is polymerized by heating. However, the viscosity of the curable composition increases as the polymerization progresses over time. The viscosity behavior of the cured composition is measured by the method described in Examples.

A cured composite can be produced by the steps described above. That is, a cured product composite according to one embodiment includes the above-described porous body and a cured product of the above-described curable composition impregnated in the porous body.

The cured product in the cured product composite contains a polymer of the first polymerizable component and a polymer of the second polymerizable component. The cured product may not contain the first polymerizable component and the second polymerizable component (all of the first polymerizable component and the second polymerizable component may be polymerized), and cured A part of the first polymerizable component and/or the second polymerizable component may remain in the product as a minor component.

EXAMPLES The present invention will be described in more detail below based on examples, but the present invention is not limited to the following examples.

The following materials were used to prepare the curable composition.
<First polymerizable component>
(A1) cyanate compound (“TA-CN”, manufactured by Mitsubishi Gas Chemical Company, Inc.)
(A2) maleimide compound (“BMI-80”, manufactured by K.I Kasei Co., Ltd.)
(A3) epoxy compound ("MA-DGIC", manufactured by Shikoku Kasei Co., Ltd.)
<Second polymerizable component>
(B1) Epoxy compound ("HP-4032D", manufactured by DIC Corporation)
(B2) vinyl compound (“BPA-AE”, manufactured by Konishi Chemical Industry Co., Ltd.)
(B3) maleimide compound (“BMI-80”, manufactured by K.I Kasei Co., Ltd.)
(B4) maleimide compound (“BMI-TMH”, manufactured by Daiwa Chemical Industry Co., Ltd.)
<First polymerization initiator>
(C1) Organic peroxide ("Perbutyl Z", NOF Corporation)
(C2) Organometallic salt (“Bis(2,4-pentanedionato)zinc (II)”, manufactured by Tokyo Chemical Industry Co., Ltd.)
(C3) Phenolic resin ("MEH8000H", manufactured by Meiwa Kasei Co., Ltd.)
<Second polymerization initiator>
(D1) Imidazole compound (“2E4MZ-CN”, manufactured by Shikoku Kasei Co., Ltd.)
(D2) Organic peroxide ("Percumyl D", manufactured by NOF Corporation)
(D3) Sulfonium salt ("San-Aid SI-150", manufactured by Sanshin Chemical Industry Co., Ltd. <Comparative polymerization initiator>
(E1) Phosphonium salt ("TPP-MK", Hokko Chemical Industry Co., Ltd.)

[Preparation of curable composition]
The first polymerizable component and the second polymerizable component were weighed into a container so as to obtain the composition (parts by mass) shown in Table 1. Furthermore, the first polymerization initiator and the second polymerization initiator are added in the amounts shown in Table 1 (phr based on the total of the first polymerizable component and the second polymerizable component), and these All mixed. Thus, curable compositions according to Examples and Comparative Examples were prepared.

[Evaluation of viscosity behavior]
The curable compositions of Examples and Comparative Examples were cured by heating at 120° C. under atmospheric pressure. Simultaneously with heating, using a rotational viscometer, the viscosity of the curable composition is measured while continuously rotating at a shear rate of 10 (1 / sec), and the curable composition with respect to the heating time. was evaluated. The viscosity was measured every few seconds until about 24 hours after the start of heating. Based on the obtained viscosity behavior (viscosity change of the curable composition with respect to heating time), evaluation was made according to the following criteria based on the viscosity increase per hour in the viscosity range of 10 ² to 10 ⁶ Pa·s. Table 1 shows the results.
S: No time region where the viscosity increase was 50000 Pa s or more was confirmed (that is, none of A, B, or C below applies)
A: A time region where the viscosity increase was 50000 Pa s or more and less than 110000 Pa s was confirmed B: A time region where the viscosity increase was 110000 Pa s or more and less than 200000 Pa s was confirmed C: The viscosity increase was confirmed A time region of 200,000 Pa·s or more was confirmed

From the evaluation results of the viscosity behavior, by using the curable composition according to the example, compared with the curable composition according to the comparative example, the semi-cured product of the curable composition can easily be in a state of excellent adhesion. I have found that it can be adjusted.

[Production of semi-cured composite]
(Preparation of porous body 1)
In a container, 40.0% by mass of amorphous boron nitride powder (manufactured by Denka Co., Ltd., oxygen content: 1.5%, boron nitride purity: 97.6%, average particle size: 6.0 μm), hexagonal boron nitride powder (manufactured by Denka Co., Ltd., oxygen content: 0.3%, boron nitride purity: 99.0%, average particle size: 30.0 μm) was measured so that it was 60.0% by mass, and the sintering aid After adding (boric acid and calcium carbonate), an organic binder and water were added and mixed, followed by drying and granulation to prepare mixed powder of nitride.

The mixed powder was filled in a mold and press-molded at a pressure of 5 MPa to obtain a compact. Next, using a cold isostatic press (CIP) device (manufactured by Kobe Steel, Ltd., trade name: ADW800), the compact was compressed by applying a pressure of 20 to 100 MPa. Then, using a batch-type high-frequency furnace (manufactured by Fuji Dempa Kogyo Co., Ltd., product name: FTH-300-1H), nitrogen is flowed into the furnace so that the flow rate is 10 L / min under standard conditions. The porous body 1 was produced by sintering the compacted compact by holding it at 2000° C. for 10 hours under a nitrogen atmosphere. The obtained porous body 1 had an average pore diameter of 1.0 μm and a porosity of 45% by volume.

(Production of porous body 2)
Porous body 2 was produced in the same manner as for porous body 1, except that the amount of sintering aid was reduced so that the porous body had an average pore diameter of 0.3 μm and a porosity of 35% by volume. .

(Preparation of porous body 3)
Porous body 3 was produced in the same manner as for porous body 1, except that the amount of the sintering aid was increased so that the porous body had an average pore diameter of 5 μm and a porosity of 65% by volume.

The porous bodies 1 to 3 produced as described above were impregnated with the curable compositions according to Examples 1 to 3, respectively, by the following method. First, the porous body and the curable composition contained in a container were placed in a vacuum heating and impregnating device (manufactured by Kyoshin Engineering Co., Ltd., trade name: G-555AT-R). Next, the inside of the apparatus was degassed for 10 minutes under the conditions of temperature: 100°C and pressure: 15 Pa. After degassing, the porous body was immersed in the curable composition for 40 minutes under the same conditions to impregnate the porous body with the curable composition.

After that, the container containing the porous body and the curable composition was taken out and placed in a pressure heating impregnation device (manufactured by Kyoshin Engineering Co., Ltd., product name: HP-4030AA-H45), and the temperature was 130 ° C. and The porous body was further impregnated with the curable composition by holding for 120 minutes under the condition of pressure: 3.5 MPa. After that, the nitride sintered body was taken out from the apparatus and heated for a predetermined time under conditions of a temperature of 120° C. and atmospheric pressure.
Semi-cured composite 1-1 (porous body 1 impregnated with the curable composition of Example 1)
Semi-cured composite 1-2 (porous body 2 impregnated with the curable composition of Example 1)
・Semi-cured composite 1-3 (porous body 3 impregnated with the curable composition of Example 1)
・Semi-cured composite 2-1 (porous body 1 impregnated with the curable composition of Example 2)
・Semi-cured composite 2-2 (porous body 2 impregnated with the curable composition of Example 2)
Semi-cured composite 2-3 (porous body 3 impregnated with the curable composition of Example 2)
・Semi-cured composite 3-1 (porous body 1 impregnated with the curable composition of Example 3)
Semi-cured composite 3-2 (impregnating the porous body 2 with the curable composition of Example 3)
・Semi-cured composite 3-3 (porous body 3 impregnated with the curable composition of Example 3)

[Evaluation of Impregnation]
The filling rate of the semi-cured material of the curable composition contained in the semi-cured material composite is calculated by the following formula:
Filling rate (volume %) = {(bulk density of semi-cured composite - bulk density of porous body) / (theoretical density of semi-cured composite - bulk density of porous body)} x 100
sought by
The bulk density of the porous body and semi-cured composite is in accordance with JIS Z8807:2012 "Method for measuring density and specific gravity by geometric measurement", and each side of the porous body and semi-cured composite It was obtained based on the volume calculated from the length (measured with a vernier caliper) and the mass of the composite of the porous body and the semi-cured material measured with an electronic balance (see JIS Z8807:2012, item 9).
The theoretical density of the semi-cured composite is given by the following formula:
Theoretical density of semi-cured composite = true density of porous body + true density of resin × (1 - bulk density of porous body / true density of boron nitride)
sought by
The true density of the porous body and resin is the volume and volume of the porous body and resin measured using a dry automatic densitometer in accordance with JIS Z8807:2012 "Method for measuring density and specific gravity by gas replacement method". It was determined from the mass (see formulas (14) to (17) in item 11 of JIS Z8807:2012).
Based on the filling factor obtained above, the impregnability was evaluated according to the following criteria. It means that the higher the filling rate, the better the impregnability (the curable composition easily impregnates the porous body). Table 2 shows the evaluation results.
A: Filling rate is 93% or more B: Filling rate is 85% or more and less than 93% C: Filling rate is less than 85%

[Evaluation of insulation]
A sample was prepared by processing the resulting semi-cured composite into a size of length×width×thickness=20 mm×20 mm×0.40 mm. The dielectric breakdown voltage of this sample was measured according to JIS C2110-1:2016 using a withstand voltage tester (manufactured by Kikusui Electronics Co., Ltd., device name: TOS-8700). Based on the measured dielectric breakdown voltage, insulation was evaluated according to the following criteria. It means that the higher the dielectric breakdown voltage, the better the insulation. Table 2 shows the evaluation results.
A: Dielectric breakdown voltage of 20 kV/mm or more B: Dielectric breakdown voltage of 10 kV/mm or more and less than 20 kV/mm C: Dielectric breakdown voltage of less than 10 kV/mm

[Preparation of cured product composite]
The resulting semi-cured composite was placed in a pressurized heating impregnation device and further heated for 5 hours under conditions of a temperature of 200° C. and atmospheric pressure, whereupon the semi-cured composite of the curable composition was further cured. Thus, a cured product composite in which no adhesion was observed was able to be produced.

Claims (10)

The first polymerizable component, the first polymerization initiator that initiates the polymerization of the first polymerizable component, the second polymerizable component, and the first polymerization initiator under different conditions. A step of impregnating the porous body with a curable composition containing a second polymerization initiator that initiates polymerization of the polymerizable component of 2;
and a step of polymerizing the first polymerizable component with the first polymerization initiator. 2. The method for producing a semi-cured composite according to claim 1, wherein the first polymerizable component contains at least one selected from the group consisting of maleimide compounds, cyanate compounds, and silicone compounds. 3. The method for producing a semi-cured composite according to claim 1, wherein said porous body has an average pore size of 1 [mu]m or more and a porosity of 30% by volume or more. The first polymerizable component, the first polymerization initiator that initiates the polymerization of the first polymerizable component, the second polymerizable component, and the first polymerization initiator under different conditions. A step of impregnating the porous body with a curable composition containing a second polymerization initiator that initiates polymerization of the polymerizable component of 2;
polymerizing the first polymerizable component with the first polymerization initiator;
and a step of polymerizing the second polymerizable component with the second polymerization initiator after polymerizing the first polymerizable component. 5. The method for producing a cured product composite according to claim 4, wherein the first polymerizable component contains at least one selected from the group consisting of maleimide compounds, cyanate compounds, and silicone compounds. 6. The method for producing a cured composite according to claim 4, wherein said porous body has an average pore size of 1 μm or more and a porosity of 30% by volume or more. A semi-cured composite comprising a porous body and a semi-cured curable composition impregnated in the porous body,
The curable composition comprises a first polymerizable component, a first polymerization initiator that initiates polymerization of the first polymerizable component, a second polymerizable component, and the first polymerization initiator. and a second polymerization initiator that initiates polymerization of the second polymerizable component under conditions different from
A semi-cured material composite, wherein the semi-cured material contains a polymer of the first polymerizable component, the second polymerizable component, and the second polymerization initiator. 8. The semi-cured composite according to claim 7, wherein said first polymerizable component contains at least one selected from the group consisting of maleimide compounds, cyanate compounds and silicone compounds. 9. The method for producing a semi-cured composite according to claim 7, wherein said porous body has an average pore size of 1 μm or more and a porosity of 30% by volume or more. The semi-cured composite according to any one of claims 7 to 9, wherein a part of said first polymerizable component remains in said semi-cured product.

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