JP6760815B2 - Resin varnish, its manufacturing method and laminated board manufacturing method - Google Patents

Description

The present invention relates to a resin varnish, a method for producing the same, and a method for producing a laminated board.

Conventionally, an epoxy resin has been used for a member used in an electronic product, for example, an insulating laminated plate or a laminated plate (copper-clad laminate) in which copper foil is laminated on one side or both sides thereof. The laminated board is made by impregnating a fibrous base material such as glass cloth with a resin varnish in which an epoxy resin, a curing agent, etc. is dissolved in a solvent, drying the prepreg, and heat-pressing the prepreg alone or in combination of two or more. Manufactured by As a curing agent for the epoxy resin, a phenol novolac resin using phenol and formaldehyde is widely used. As the solvent for the resin varnish, a polar solvent such as methyl ethyl ketone is generally used.

In recent years, as the performance of electronic products has been improved, it is required to further improve the high glass transition temperature, low dielectric constant, and low dielectric loss tangent of the resin constituting the laminated plate.
Although the electrical characteristics (low dielectric constant, low dielectric loss tangent) of the cured product obtained by curing the epoxy resin with phenol novolac resin can meet the levels required for general-purpose electronic products, high-performance electronic products (smartphones, It is difficult to meet the level required for tablets, etc.). In addition, this cured product has a low glass transition temperature and a high coefficient of thermal expansion for use in power devices that have been developed in recent years.

Non-Patent Document 1 reports that a polyvalent phenol-cured bismaleimide resin obtained by curing a bismaleimide compound with an allyl novolac type phenol resin exhibits a high glass transition temperature, a high thermal decomposition temperature, and a low thermal expansion rate.

Reio Takaiwa and 2 others, "Research on multivalent phenol-cured bismaleimide resin", [оnline], 26th Electronics Packaging Society Spring Lecture Meeting (March 7-9, 2012), [2016 Search on June 23], Internet, <URL: https://www.jstage.jst.go.jp/article/ejisso/26/0/26_32/_pdf>

However, the polyvalent phenol-cured bismaleimide resin has a high dielectric constant and dielectric loss tangent. Further, due to the hardness derived from the curing of maleimide, there is a problem that the adhesion to the copper foil, the fibrous base material and the like is poor. In addition, there is a problem that the gel time is long when the bismaleimide compound is cured with the allyl novolac type phenol resin. If the gel time is long, the productivity of laminated boards and the like deteriorates.

The present invention has been made in view of the above circumstances, and is a maleimide-based resin varnish capable of obtaining a cured product having a short gel time, low dielectric constant, low dielectric loss tangent, and high adhesion, a method for producing the same, and the resin varnish. It is an object of the present invention to provide a method for manufacturing a laminated board using.

The present invention has the following aspects.
<1> Contains a maleimide compound having two or more maleimide groups, an allyl group-containing resin, and a solvent.
The allyl group-containing resin is represented by one or both of the structural unit (1) represented by the following formula (1) and the structural unit (2) represented by the following formula (2), and the following formula (3). It has a structural unit (3) represented by it and a structural unit (4) represented by the following formula (4).
The total content of the structural unit (2) and the structural unit (4) is the same as that of the structural unit (1), the structural unit (2), the structural unit (3), and the structural unit (4). Resin varnish which is 10 to 80 mol% based on the total.

［式中、Ａｒはベンゼン環またはナフタレン環を示し、Ｒは下記式（ｒ１）または（ｒ２）で表される基を示し、ｐおよびｑはそれぞれ独立に０または１を示し、−＊および−＊＊はそれぞれ結合手を示す。−＊は、他の構成単位に結合し、−（Ｒ）_ｐ−＊＊の−＊＊は、ｐが０である場合は他の構成単位または水素原子に結合し、ｐが１である場合は他の構成単位に結合し、−（Ｒ）_ｑ−＊＊の−＊＊は、ｑが０である場合は他の構成単位または水素原子に結合し、ｑが１である場合は他の構成単位に結合する。］

[In the formula, Ar represents a benzene ring or a naphthalene ring, R represents a group represented by the following formula (r1) or (r2), p and q each independently represent 0 or 1, and − * and − ** indicates a bonder. -* Bonds to another structural unit, and-(R) _p -**-** binds to another structural unit or hydrogen atom when p is 0, and when p is 1. Is bonded to another structural unit, and-(R) _q -**-** is bonded to another structural unit or hydrogen atom when q is 0, and other when q is 1. Combine into building blocks. ]

<2> The resin varnish of <1>, wherein the molar ratio (maleimide group / allyl group) of the maleimide group of the maleimide compound to the allyl group of the allyl group-containing resin is 0.2 to 1.4.
<3> A method for producing a resin varnish by mixing a maleimide compound having two or more maleimide groups, an allyl group-containing resin, and a solvent.
The allyl group-containing resin is represented by one or both of the structural unit (1) represented by the formula (1) and the structural unit (2) represented by the formula (2), and the structural unit (3). It has a structural unit (3) represented by the above formula (4) and a structural unit (4) represented by the above formula (4).
The total content of the structural unit (2) and the structural unit (4) is the same as that of the structural unit (1), the structural unit (2), the structural unit (3), and the structural unit (4). A method for producing a resin varnish, which is 10 to 80 mol% of the total.
<4> The method for producing a resin varnish according to <3>, wherein the maleimide compound and the allyl group-containing resin are prereacted after the mixing.
<5> Production of a laminated board in which the fibrous base material is impregnated with the resin varnish of <1> or <2>, and the fibrous base material impregnated with the resin varnish is heated and pressed and cured to obtain a laminated board. Method.

According to the present invention, there is provided a maleimide-based resin varnish capable of obtaining a cured product having a short gel time, a low dielectric constant, a low dielectric loss tangent, and a high adhesion, a method for producing the same, and a method for producing a laminated board using the resin varnish. it can.

≪Resin varnish≫
The resin varnish of the present invention (hereinafter, also referred to as "the present resin varnish") contains a maleimide compound having two or more maleimide groups, a specific allyl group-containing resin, and a solvent.
The allyl group-containing resin functions as a maleimide curing agent. The "maleimide curing agent" means a curing agent for curing the maleimide compound.
The resin varnish may further contain a curing reaction catalyst.
The resin varnish may further contain components other than the maleimide compound, the allyl group-containing resin, the solvent and the curing reaction catalyst.
In the present resin varnish, a part of the maleimide group of the maleimide compound may be in a state of reacting with a part of the allyl group or the hydroxy group of the allyl group-containing resin.

<Allyl group-containing resin>
The allyl group-containing resin in the present invention includes one or both of the structural unit (1) represented by the following formula (1) and the structural unit (2) represented by the following formula (2), and the following formula (3). ), And a structural unit (4) represented by the following formula (4).
“Constituent unit” indicates a unit constituting the polymer.

［式中、Ａｒはベンゼン環またはナフタレン環を示し、Ｒは下記式（ｒ１）または（ｒ２）で表される基を示し、ｐおよびｑはそれぞれ独立に０または１を示し、−＊および−＊＊はそれぞれ結合手を示す。−＊は、他の構成単位に結合し、−（Ｒ）_ｐ−＊＊の−＊＊は、ｐが０である場合は他の構成単位または水素原子に結合し、ｐが１である場合は他の構成単位に結合し、−（Ｒ）_ｑ−＊＊の−＊＊は、ｑが０である場合は他の構成単位または水素原子に結合し、ｑが１である場合は他の構成単位に結合する。］

[In the formula, Ar represents a benzene ring or a naphthalene ring, R represents a group represented by the following formula (r1) or (r2), p and q each independently represent 0 or 1, and − * and − ** indicates a bonder. -* Bonds to another structural unit, and-(R) _p -**-** binds to another structural unit or hydrogen atom when p is 0, and when p is 1. Is bonded to another structural unit, and-(R) _q -**-** is bonded to another structural unit or hydrogen atom when q is 0, and other when q is 1. Combine into building blocks. ]

The allyl group-containing resin is derived from the structural units (1) to (4) and contains a plurality of Ars. In the allyl group-containing resin, a plurality of Ars are bonded to each other via one R and are not directly bonded to each other.

Therefore, the connecting hand (-*) extending from R of the structural unit (1) or (2) is bound to the connecting hand (-*) extending from Ar of the structural unit (3) or (4).
The bond extending from Ar of the structural unit (3) or (4) is the bond extending from R of the structural unit (1) or (2), and another structural unit (3) in which at least one of p and q is 1. Alternatively, it bonds to a bond extending from R in (4) or a hydrogen atom.
A bond extending from R of the structural unit (3) or (4) in which at least one of p and q is 1, is bonded to a bond extending from Ar of another structural unit (3) or (4).
Here, in the structural unit (3) or (4), the connecting hands extending from Ar are (R) _p -** where _p is 0 and (R) _q -** where q is 0. Is one of. The bond extending from R is either (R) _p -** where _p is 1 and (R) _q -** where q is 1.

In the formulas (1) to (4), Ar may be a benzene ring or a naphthalene ring, and a benzene ring is preferable.
R may be a group represented by the formula (r1) or a group represented by the formula (r2).
In the formula (r1), the bonding positions of the two methylene groups in the biphenylene ring are not particularly limited, but when the allyl group-containing resin is manufactured by the manufacturing method (I) described later, it is represented by the formula (r1). The 4-position and 4'-position are preferable from the viewpoint that the reactivity of the cross-linking agent (B) corresponding to the group with the monomer (A) is good.
In the above formula (r2), the bonding positions of the two methylene groups on the benzene ring are not particularly limited, but when the allyl group-containing resin is produced by the production method (I) described later, the group represented by the formula (r1). From the viewpoint of good reactivity of the cross-linking agent (B) corresponding to the above with the monomer (A), the para-position is preferable.
The plurality of Ars contained in the allyl group-containing resin may be the same or different. When the allyl group-containing resin contains a plurality of Rs, the plurality of Rs may be the same or different.

Specific examples of the structural unit (1) include a structural unit represented by the following formulas (1-1), (1-2) or (1-3). Among these, the structural unit represented by the formula (1-1) is preferable.

The bonding positions of the -R- * and aldehyde groups in the benzene ring of the structural unit represented by the formula (1-1) are not particularly limited.
The bonding positions of the -R- * and aldehyde groups in the naphthalene ring of the structural unit represented by the formula (1-2) or (1-3) are not particularly limited. For example, in the formula (1-2), when the position where the hydroxy group is bonded is set to the 1-position, -R- * or the aldehyde group may be bonded at any of the 2 to 8 positions. In the formula (1-3), when the position where the hydroxy group is bonded is set to the 2-position, -R- * or the aldehyde group may be bonded at any of the 1st, 3rd to 8th positions.
The structural unit (1) is preferably a structural unit represented by the formula (1-1) in which the bond position of the aldehyde group is the ortho position with respect to the hydroxy group. With such a structural unit, when the allyl group-containing resin is produced by the production method (I) described later, the cross-linking agent (B) of the monomer (A) corresponding to the structural unit represented by the formula (1-1). ) Is good, and the monomer (A) can be easily recovered and recycled.
The structural unit (1) contained in the allyl group-containing resin may be one type or two or more types.

Specifically, as the structural unit (2), the aldehyde group (-CHO) in the above formulas (1-1), (1-2) or (1-3) is -CH = N-CH ₂ -CH = CH _2. The structural unit of the structure converted to is mentioned. Among these, a structural unit having a structure in which the aldehyde group (-CHO) in the formula (1-1) is converted to -CH = N-CH ₂ -CH = CH ₂ is preferable, and -CH = N-CH ₂ -CH = It is particularly preferable that the bond position of CH _{2 is} the ortho position with respect to the hydroxy group.
The structural unit (2) contained in the allyl group-containing resin may be one type or two or more types.

Specific examples of the structural unit (3) include a structural unit represented by the following formulas (3-1), (3-2) or (3-3). Among these, the structural unit represented by the formula (3-1) is preferable.

The bonding positions of − *, − (R) _p − **, − (R) _q − **, and the aldehyde group in the benzene ring of the structural unit represented by the formula (3-1) are not particularly limited.
The bond positions of-*,-(R) _p -**,-(R) _q -**, and aldehyde groups in the naphthalene ring of the structural unit represented by the formula (3-2) or (3-3) are There is no particular limitation. For example, in the formula (3-2), when the position where the hydroxy group is bonded is set to the 1-position, -R- * or the aldehyde group may be bonded at any of the 2 to 8 positions. In the formula (3-3), when the position where the hydroxy group is bonded is set to the 2-position, -R- * or the aldehyde group may be bonded at any of the 1st, 3rd to 8th positions.
The structural unit (3) is preferably a structural unit represented by the formula (3-1) in which the bond position of the aldehyde group is the ortho position with respect to the hydroxy group. With such a structural unit, when the allyl group-containing resin is produced by the production method (I) described later, the cross-linking agent (B) of the monomer (A) corresponding to the structural unit represented by the formula (3-1). ) Is good, and the monomer (A) can be easily recovered and recycled.
The structural unit (3) contained in the allyl group-containing resin may be one type or two or more types.

Specifically, as the structural unit (4), the aldehyde group (-CHO) in the formulas (3-1), (3-2) or (3-3) is -CH = N-CH ₂ -CH = CH _2. The structural unit of the structure converted to is mentioned. Among these, a structural unit having a structure in which the aldehyde group (-CHO) in the formula (3-1) is converted to -CH = N-CH ₂ -CH = CH ₂ is preferable, and -CH = N-CH ₂ -CH = It is particularly preferable that the bond position of CH _{2 is} the ortho position with respect to the hydroxy group.
The structural unit (4) contained in the allyl group-containing resin may be one type or two or more types.

If necessary, the allyl group-containing resin contains structural units other than the structural unit (1), the structural unit (2), the structural unit (3), and the structural unit (4), as long as the effects of the present invention are not impaired. You may also have.

In the allyl group-containing resin, the total content of the structural unit (2) and the structural unit (4) is the structural unit (1), the structural unit (2), the structural unit (3), and the above. It is 10 to 80 mol% with respect to the total (100 mol%) with the structural unit (4), preferably 25 to 70 mol%, and particularly preferably 25 to 50 mol%. This ratio is equal to the ratio (mol%) of the allyl group to the total of the aldehyde group and the allyl group in the allyl group-containing resin. When this ratio is equal to or higher than the lower limit of the above range, the gel time when curing the resin varnish is shortened. In addition, the obtained cured product exhibits high glass transition temperature, high thermal decomposition temperature, low dielectric constant, low dielectric loss tangent, and high adhesion. When this ratio is not more than the upper limit of the above range, the allyl group-containing resin has excellent solubility in a polar solvent such as methyl ethyl ketone, and the allyl group-containing resin can be dissolved in the polar solvent to form a resin varnish. In addition, the cost can be suppressed.

In the allyl group-containing resin, the structural unit (1), the structural unit (2), the structural unit (3), and the structural unit (4) per molecule of the polymer constituting the allyl group-containing resin. The total number is preferably 2 to 62. When the total number is not more than the above upper limit value, the mass average molecular weight (Mw) of the allyl group-containing resin becomes low, so that the allyl group-containing resin can be dissolved in a polar solvent to form a resin varnish.

The mass average molecular weight (Mw) of the allyl group-containing resin is preferably 300 to 8000, more preferably 2000 to 5000. When Mw is not more than the above upper limit value, the solution viscosity of the allyl group-containing resin becomes sufficiently low. When Mw is at least the above lower limit value, the crystallinity of the allyl group-containing resin can be suppressed, and the solubility when dissolved in a solvent is excellent.
The dispersity (Mw / number average molecular weight (Mn)) of the allyl group-containing resin is preferably 1.20 to 5.00.
In the present invention, Mw and Mn are values measured by gel permeation chromatography (GPC) using polystyrene as a standard substance.

(Manufacturing method of allyl group-containing resin)
Examples of the method for producing the allyl group-containing resin include the following production method (I).
Production method (I): At least one monomer (A) selected from the group consisting of monohydroxybenzaldehyde and monohydroxynaphthaldehyde, a compound represented by the following formula (b1), and a compound represented by the following formula (b2). A step of reacting with at least one cross-linking agent (B) selected from the group consisting of compounds to obtain an aldehyde group-containing resin containing the structural unit (1) and the structural unit (3).
A step of reacting the aldehyde group-containing resin with 10 to 80 mol% of allylamine with the aldehyde group of the aldehyde group-containing resin to obtain the allyl group-containing resin.
A method for producing an allyl group-containing resin having.

［式中、Ｘは炭素数１〜４のアルコキシ基またはハロゲン原子である。］

[In the formula, X is an alkoxy group or a halogen atom having 1 to 4 carbon atoms. ]

(Monomer (A))
Examples of monohydroxybenzaldehyde include orthohydroxybenzaldehyde, parahydroxybenzaldehyde, and metahydroxybenzaldehyde.
Examples of the monohydroxynaphthaldehyde include 1-hydroxy-2-naphthaldehyde, 2-hydroxy-1-naphthaldehyde, 6-hydroxy-2-naphthaldehyde and the like.
Any one of these may be used alone, or two or more thereof may be used in combination.
As the monomer (A), orthohydroxybenzaldehyde is preferable because it has good reactivity with the cross-linking agent (B) and the monomer remaining in the reaction can be easily recovered and recycled.

(Crosslinking agent (B))
In the formula (b1) or (b2), examples of the halogen atom of X include a chlorine atom and a bromine atom.
Examples of the compound represented by the formula (b1) include 4,4'-bis (alkoxymethyl) biphenyl, 2,2'-bis (alkoxymethyl) biphenyl, and 2,4'-bis (alkoxymethyl) biphenyl, 4 , 4'-bis (methyl halide) biphenyl, 2,2'-bis (methyl halogenated) biphenyl, 2,4'-bis (methyl halogenated) biphenyl, etc. (However, the number of carbon atoms in the alkoxy group is 1 to 4 Is mentioned.).
Examples of the compound represented by the formula (b2) include paraxylylene glycol dialkyl ether, metaxylylene glycol dialkyl ether, 1,4-bis (methyl halide) benzene and the like (however, the number of carbon atoms of the alkyl group is 1 to 1). 4).
These may be used alone or in combination of two or more.
Among the above, the cross-linking agent (B) is relatively inexpensive and has good reactivity with the monomer (A). Therefore, 4,4'-bis (alkoxymethyl) biphenyl, 4,4' -Bis (methyl halide) biphenyl, paraxylylene glycol dialkyl ether, 1,4-bis (methyl halogenated) benzene are preferred.

(Reaction between monomer (A) and cross-linking agent (B))
In the reaction between the monomer (A) and the cross-linking agent (B), Ar of a plurality of monomers (A) is cross-linked by the cross-linking agent (B), and an aldehyde having the structural unit (1) and the structural unit (3). A group-containing resin is produced.

In the reaction between the monomer (A) and the cross-linking agent (B), the molar ratio of the cross-linking agent (B) to the monomer (A) (cross-linking agent (B) / monomer (A)) was 0.01 to 0.99. It is preferably 0.05 to 0.60, and more preferably 0.05 to 0.60.
If the ratio of the cross-linking agent (B) to the monomer (A) is too low, the yield may decrease. If the ratio of the cross-linking agent (B) to the monomer (A) is too high, the reaction between the monomer (A) and the cross-linking agent (B) takes a long time, and the productivity may decrease.

The reaction between the monomer (A) and the cross-linking agent (B) may be carried out in the presence of an acidic catalyst. When the reaction is carried out under an acidic catalyst, the reaction rate between the monomer (A) and the cross-linking agent (B) is improved. In particular, when X contained in the cross-linking agent (B) is an alkoxy group, it is preferably carried out in the presence of an acidic catalyst.
When the X contained in the cross-linking agent (B) is a halogen atom, it is not necessary to add an acidic catalyst separately. When X is a halogen atom, the halogen atom is desorbed by the heat of the reaction to become HX. Since this HX functions as an acidic catalyst, the reaction rate becomes sufficiently high without adding an acidic catalyst separately.

The acidic catalyst is not particularly limited as long as the reaction proceeds, and examples thereof include inorganic acids, organic acids, and alkaline metal compounds. Specific examples include hydrochloric acid, sulfuric acid, phosphoric acid, oxalic acid, trifluoroacetic acid, p-toluenesulfonic acid, methanesulfonic acid, boron trifluoride, aluminum chloride, iron chloride, zinc chloride and the like. The acidic catalyst may be used alone or in combination of two or more.

The amount of the acidic catalyst used is preferably 0.01 to 10% by mass, more preferably 0.10 to 1.00% by mass, based on the monomer (A).
If the amount of the acidic catalyst used is too small, the effect of improving the reaction rate may be insufficient, and if the amount used is too large, the reaction proceeds rapidly and it becomes difficult to control the reaction.

The reaction temperature of the monomer (A) and the cross-linking agent (B) is preferably 10 to 250 ° C, more preferably 60 to 200 ° C. If the reaction temperature is too low, the reaction will not proceed, and if it is too high, it will be difficult to control the reaction, and it will be difficult to stably obtain the desired aldehyde group-containing resin.
At the end of the reaction, an alkali may be added to the resulting reaction product to neutralize the acidic catalyst.

The reaction product obtained by the reaction of the monomer (A) and the cross-linking agent (B) contains an aldehyde group-containing resin having the structural unit (1) and the structural unit (3).
This reaction product is left as it is, or if necessary, it is subjected to treatments such as removal of unreacted raw materials by distillation, concentration, purification (washing, column chromatography, etc.), and the next step (aldehyde group-containing resin). And allylamine).

(Reaction between aldehyde group-containing resin and allylamine)
When the aldehyde group-containing resin generated by the reaction of the monomer (A) and the cross-linking agent (B) is reacted with allylamine, the aldehyde group of the aldehyde group-containing resin (aldehyde groups of the constituent units (1) and (3)). Is converted to -CH = N-CH ₂ -CH = CH ₂ .
At this time, the allyl group-containing resin is produced by reacting 10 to 80 mol% of allylamine with the aldehyde group (100 mol%) of the aldehyde group-containing resin.
The amount of allylamine to be reacted with the aldehyde group-containing resin is preferably 25 to 70 mol%, particularly preferably 25 to 50 mol% with respect to the aldehyde group of the aldehyde group-containing resin.
Therefore, in the reaction between the aldehyde group-containing resin and allylamine, the molar ratio (amino group / aldehyde group) of the amino group of allylamine to the aldehyde group of the aldehyde group-containing resin is preferably 0.10 to 0.80, preferably 0.25. ~ 0.70 is more preferable, and 0.25 to 0.50 is particularly preferable.

The reaction temperature of the aldehyde group-containing resin and allylamine is preferably 10 to 150 ° C, more preferably 30 to 90 ° C. If the reaction temperature is too low, the reaction will not proceed easily. When the reaction temperature is equal to or lower than the boiling point of allylamine (97 ° C.), the production stability is excellent.

The reaction product obtained by the reaction of the aldehyde group-containing resin with allylamine contains the allyl group-containing resin.
After the reaction, if necessary, the reaction product may be subjected to treatments such as removal of unreacted raw materials by distillation and the like, concentration and purification (washing, column chromatography, etc.).

<Maleimide compound>
The maleimide compound is not particularly limited as long as it is a compound having two or more maleimide groups, and examples thereof include bismaleimide compounds and polyphenylmethane maleimide.
Examples of the bismaleimide compound include 4,4'-diphenylmethane bismaleimide (for example, BMI-1000 manufactured by Daiwa Kasei Kogyo Co., Ltd.), alkyl bismaleimide, diphenylmethane bismaleimide, phenylene bismaleimide, bisphenol A diphenyl ether bismaleimide, 3,3 '-Dimethyl-5,5'-diethyl-4,4'-diphenylmethanebismaleimide, 4-methyl-1,3-phenylene bismaleimide, 1,6'-bismaleimide- (2,2,4-trimethyl) hexane , 4,4'-Diphenylether bismaleimide, 4,4'-diphenylsulphon bismaleimide, 1,3-bis (3-maleimidephenoxy) benzene, 1,3-bis (4-maleimidephenoxy) benzene and the like.
Polyphenylmethane maleimide is a polymer in which three or more benzene rings substituted with maleimide groups are bonded via a methylene group, and examples thereof include BMI-2300 manufactured by Daiwa Kasei Kogyo Co., Ltd.
Maleimide compounds include 4,4'-diphenylmethanebismaleimide and polyphenyl because they have good compatibility with the allyl group-containing resin, have better heat resistance and adhesion of cured products, and are relatively inexpensive. Methanemaleimide is preferred.
These maleimide compounds may be used alone or in combination of two or more.

The content of the maleimide compound in the resin varnish is such that the molar ratio (maleimide group / allyl group) of the maleimide group of the maleimide compound to the allyl group of the allyl group-containing resin is 0.2 to 1.4. preferable. The maleimide group / allyl group is more preferably 0.3 to 1.2, and even more preferably 0.4 to 1.1. When the maleimide group / allyl group is at least the lower limit of the above range, the curing temperature of the resin varnish can be lowered, for example, 200 ° C. or less. When the maleimide group / allyl group is equal to or higher than the lower limit of the above range, the cured product of this resin varnish exhibits a higher glass transition temperature, a higher thermal decomposition temperature, a low linear expansion coefficient, a low dielectric constant, and a low dielectric loss tangent. Become.

<Solvent>
The solvent is not particularly limited as long as it dissolves the components contained in the resin varnish (the allyl group-containing resin, the maleimide compound, a curing reaction catalyst, etc., if necessary).
A polar solvent is typically used as the solvent. Examples of the polar solvent include ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, diethyl ketone, methyl propyl ketone, methyl amyl ketone, isophorone, diisobutyl ketone, diacetone alcohol, and cyclohexanone, N, N-dimethylformamide, and N-. Examples thereof include methyl-2-pyrrolidone, methanol, ethanol, butanol, ethyl acetate, butyl acetate, methyl cellosolve, ethyl diglycol acetate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, tetrahydrofuran and the like. Any one of these solvents may be used alone, or two or more thereof may be used in combination. Among the above, a ketone solvent is preferable, and methyl ethyl ketone is particularly preferable.

The content of the solvent in the resin varnish is appropriately set according to the solid content concentration of the resin varnish.
The solid content concentration of the present resin varnish varies depending on the application, but is preferably 30 to 80% by mass, more preferably 50 to 70% by mass.
The solid content concentration of the resin varnish is the ratio of the mass of the resin varnish excluding the solvent to the total mass of the resin varnish.

<Curing reaction catalyst>
As the curing reaction catalyst, for example, one having an action of accelerating the reaction between the allyl group and the maleimide group can be used. Examples of the curing reaction catalyst having such an action include imidazole compounds and organic peroxides. Examples of the imidazole compound include 2-ethyl-4-methylimidazole, 2-methylimidazole, 2-ethylimidazole, 2,4-dimethylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 2 -Phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 1-vinyl-2-methyl Imidazole, 1-propyl-2-methylimidazole, 2-isopropylimidazole, 1-cyanomethyl-2-methyl-imidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1 Examples thereof include imidazoles such as −cyanoethyl-2-phenylimidazole. Examples of the organic peroxide include ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxydicarbonates, peroxyesters and the like. In the dialkyl peroxide, the alkyl group may be substituted with a phenyl group or the like.
Of the above, 2-ethyl-4-methylimidazole is preferable for imidazoles, and dialkyl peroxide, which is a dialkyl peroxide, is more preferable for organic peroxides. They are relatively stable at high temperatures, have good solvent solubility and are easy to handle.

Any one of these curing reaction catalysts may be used alone, or two or more of them may be used in combination.
The content of the curing reaction catalyst in the resin varnish is preferably 0.1 to 5.0% by mass with respect to the maleimide compound.

<Other ingredients>
Examples of other components include inorganic fillers (for example, carbon black, glass cloth, silica, etc.), waxes, flame retardants, coupling agents, and other maleimide curing agents other than the allyl group-containing resin (hereinafter, also referred to as other curing agents). ), Filler, mold release agent, surface treatment agent, colorant, flexibility imparting agent and the like.
As the other curing agent, conventionally known maleimide curing agents can be used, and examples thereof include novolac type resins such as allyl novolac type phenol resins.
The content of the other curing agent in the resin varnish is preferably 10% by mass or less, particularly preferably 0% by mass, based on the solid content (100% by mass) of the present resin varnish in terms of the effect of the present invention.
The solid content of the resin varnish is the portion of the resin varnish from which the solvent has been removed.

Examples of the filler include carbon black, crystalline silica powder, molten silica powder, quartz glass powder, talc, calcium silicate powder, zirconium silicate powder, alumina powder, calcium carbonate powder, and the like, and are crystalline. Silica powder and meltable silica powder are preferable.
Examples of the release agent include various waxes such as carnauba wax.
Examples of the surface treatment agent include known silane coupling agents and the like.
Examples of the colorant include carbon black and the like.
Examples of the flexibility-imparting agent include silicone resin, butadiene-acrylonitrile rubber, and the like.

<Manufacturing method of resin varnish>
The present resin varnish can be produced, for example, by mixing the maleimide compound, the allyl group-containing resin, and the solvent. Mixing of each component can be carried out by a conventional method.
As the maleimide compound, a commercially available product can be used.
The allyl group-containing resin can be produced by the above-mentioned production method (I).
When or after mixing the maleimide compound, the allyl group-containing resin, and the solvent, a curing reaction catalyst or other components may be further mixed, if necessary.
After mixing the maleimide compound, the allyl group-containing resin, and the solvent, the maleimide compound and the allyl group-containing resin may be prereacted. By performing a pre-reaction on the varnished mixture obtained by the mixing, it is possible to suppress the precipitation of the highly crystalline maleimide compound from the resin varnish.
The reaction temperature at the time of carrying out the pre-reaction is preferably 50 to 150 ° C, more preferably 70 to 130 ° C, still more preferably 80 to 120 ° C. If the reaction temperature is too low, the reaction will not proceed, and if it is too high, it will be difficult to control the reaction, and it will be difficult to stably obtain the desired resin varnish.

Since this resin varnish contains a maleimide compound and an allyl group-containing resin, it can be cured by heating to obtain a cured product.
The heating temperature (curing temperature) when curing the resin varnish is preferably 60 to 250 ° C.
As an example of the curing operation, a method of performing pre-curing at the above-mentioned suitable temperature for 30 seconds or more and 1 hour or less, removing the solvent, and then further performing post-curing at the above-mentioned suitable temperature for 1 to 20 hours is used. Can be mentioned.

<Action effect>
Since the allyl group-containing resin is used as the curing agent in this resin varnish, the gel time at the time of curing is shorter than that in the case of using the allyl phenol resin. Further, since the cured product of this resin varnish uses a maleimide compound, it exhibits a high glass transition temperature, a high thermal decomposition temperature, and a low coefficient of linear thermal expansion. In addition, compared to a cured product obtained by curing a maleimide compound with an allylphenol resin, it has excellent adhesion to other members (for example, copper foil used for copper-clad laminates, fibrous base material such as glass cloth, etc.). It has a low dielectric constant and a low dielectric loss tangent.

Since the allyl group-containing resin has a hydroxy group and -CH = N-CH ₂ -CH = CH ₂ and also has an aldehyde group in some cases, when the resin varnish is heated and cured, a solvent is used. It is considered that volatilization and the following reactions (1) to (5) occur and the mixture is cured.
(1) Reaction of an allyl group with a maleimide group.
(2) Reaction of hydroxy group and maleimide group.
(3) Reaction between allyl groups.
(4) Reaction between maleimide groups.
(5) Reaction of the imine moiety of -CH = N-CH ₂ -CH = CH ₂ with an aldehyde group.
It is considered that the inclusion of imine groups in the resin contributes to shortening the gel time and improving the adhesion.

Further, the allyl group-containing resin is excellent in solubility in a solvent generally used for dissolving a maleimide compound. Therefore, it is possible to obtain a resin varnish in which both the allyl group-containing resin and the maleimide compound are dissolved in a solvent.
As the solvent, a polar solvent such as methyl ethyl ketone is generally used. Since the allyl group-containing resin has an aldehyde group, it is considered that the resin has high solubility in such a solvent.

The allyl group-containing resin can be cured alone by the reactions (3) and (5) above without being combined with the maleimide compound. However, by combining with a maleimide compound, the curing temperature can be lowered and the glass transition temperature can be increased as compared with the case of curing alone. Therefore, it is preferable to combine it with a maleimide compound and subject it to a curing reaction.

The use of this resin varnish is not particularly limited. For example, it may be similar to the use of a known thermosetting molding material, and examples thereof include a sealing material, a film material, and a laminated material. More specific examples of applications include semiconductor encapsulation materials, resin materials for encapsulating electronic components, electrical insulation materials, resin materials for copper-clad laminates, build-up laminate materials, resist materials, and liquid crystal color filters. Examples thereof include resin materials, paints, various coating agents, adhesives, fiber reinforced plastic (FRP) materials, and the like.
The cured product obtained from this resin varnish has a high glass transition temperature, a high thermal decomposition temperature, a low thermal expansion rate, a low dielectric constant, and a low dielectric loss tangent, and is excellent in heat resistance and insulating properties. In addition, it has excellent adhesion to other members (for example, copper foil used for copper-clad laminates, fibrous base materials such as glass cloth, etc.). Therefore, this resin varnish is useful as a material for manufacturing laminated plates used for electronic parts.

≪Manufacturing method of laminated board≫
In the method for producing a laminated board of the present invention, the fibrous base material is impregnated with the resin varnish, and the fibrous base material impregnated with the resin varnish is heated and pressed to be cured to obtain a laminated board.

The laminated board manufactured by the method for manufacturing a laminated board of the present invention includes a fiber-reinforced resin layer containing a fibrous base material and a cured product of the present resin varnish. The number of fiber-reinforced resin layers included in the laminated board may be one layer or two or more layers.
The laminated board may further include a layer other than the fiber reinforced resin layer. Examples of the other layer include a metal foil layer such as copper foil.

Examples of the fibrous base material include inorganic fibers such as glass fiber, carbon fiber, ceramic fiber and stainless fiber; natural fiber such as cotton, linen and paper; synthetic organic fiber such as polyester resin and polyamide resin; and the like. Any one of these may be used alone, or two or more thereof may be used in combination.
The shape of the fibrous base material is not particularly limited, and examples thereof include short fibers, yarns, mats, and sheets.

As one embodiment of the method for producing a laminated board of the present invention, the fibrous base material is impregnated with the resin varnish and dried (solvent is removed) to obtain a prepreg, and a plurality of the prepregs are laminated as needed. If necessary, a method of further laminating a metal foil on one side or both sides of the prepreg or a laminate thereof and heating and pressurizing the prepreg or a laminate thereof to cure the prepreg.

The amount of the resin varnish impregnated in the fibrous base material is not particularly limited. For example, the solid content of the present resin varnish is about 30 to 50% by mass with respect to the fibrous base material (100% by mass).
The above-mentioned curing temperature is preferable as the heating temperature when the fibrous base material impregnated with the resin varnish is heated and pressurized. The pressurizing condition is preferably ² to ²⁰ kN / m ² .

<Action effect>
The laminated board obtained by the method for producing a laminated board of the present invention includes a fiber-reinforced resin layer containing a fibrous base material and a cured product of the present resin varnish, and the cured product is high in the fiber-reinforced resin layer. Since it has a glass transition temperature, a high thermal decomposition temperature, a low thermal expansion rate, a low dielectric constant, and a low dielectric loss tangent, it is excellent in heat resistance and insulation. Further, in the case where the metal foil layer is provided, the adhesion between the metal foil layer and the fiber reinforced resin layer and the adhesion between the fibrous base material and the cured product of the present resin varnish in the fiber reinforced resin layer are improved. Excellent. Moreover, since the gel time of this resin varnish is short, the productivity of the laminated board is excellent.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the examples.
In each of the following examples, "%" indicates "mass%" unless otherwise specified.
The measurement methods used in each of the following examples are shown below.

[Mass average molecular weight (Mw), dispersity (Mw / Mn) of resin]
The standard material was measured as polystyrene using the GPC device and column below.
GPC device: HLC8120 GPC manufactured by Tosoh Corporation.
Column: TSKgel G3000HXL + G2000H + G2000H.

[Resin softening point]
The softening point (° C.) was measured according to JIS K 6910: 1999.

[Melted viscosity of resin]
The melt viscosity (P) at 150 ° C. was measured with a melt viscometer (CAP2000 VISCOMETER manufactured by Brookfield) set at 150 ° C.

[Glass transition temperature of cured product]
The obtained molded product was processed into a size of 10.0 mm in width × 5.5 mm in length × 1.5 mm in thickness to prepare a measurement sample. For this measurement sample, tan δ was measured in the range of 30 ° C. to 350 ° C. at a heating rate of 2 ° C./min using a viscoelasticity measuring device (DMA7100 manufactured by Hitachi High-Tech Science Co., Ltd.) to determine the glass transition temperature (° C.). It was. The glass transition temperature of the cured product is preferably 300 ° C. or higher.

[5% thermal decomposition temperature of cured product]
The obtained molded product was finely pulverized and used as a measurement sample. For this measurement sample, the thermogravimetric weight loss was measured in the range of 30 to 800 ° C. at a heating rate of 10 ° C./min in an air atmosphere using a differential thermogravimetric simultaneous measuring device (TG / DTA6300 manufactured by Seiko Instruments). The 5% thermal decomposition temperature (° C.) was determined. The 5% thermal decomposition temperature of the cured product is preferably 365 ° C. or higher.

[Relative permittivity of cured product, dielectric loss tangent]
The obtained molded product was processed into a size of width 50.0 mm × length 50.0 mm × thickness 1.5 mm to prepare a measurement sample. The relative permittivity (ε _r ) and the dielectric loss tangent (tan δ) at a frequency of 1 GHz were determined for this measurement sample by the cavity resonance perturbation method. The relative permittivity of the cured product is preferably 4.00 or less. The dielectric loss tangent of the cured product is preferably 0.01 or less.

[Coefficient of linear expansion of cured product]
The obtained molded product was processed into a size of width 5.0 mm × length 5.0 mm × thickness 1.5 mm to prepare a measurement sample. This measurement sample was measured in the range of 30 ° C. to 300 ° C. at a heating rate of 2 ° C./min using a thermomechanical analyzer (TMA7100 manufactured by Hitachi High-Tech Science Co., Ltd.) to determine the coefficient of linear expansion (ppm). .. The coefficient of linear expansion at room temperature indicates the coefficient of linear expansion at 30 ° C. The coefficient of linear expansion of the cured product at room temperature is preferably 50 ppm or less.

[Gel time]
The gel time (gelation time) (seconds) of the resin varnish was measured at 170 ° C. by a method according to JIS K 6910: 2007.
Separately, for the resin varnishes of each example, a catalyst-free thermosetting molding material was prepared in the same manner except that dicumyl peroxide was not blended. Further, a resin varnish was prepared in the same manner except that 2-ethyl-4-imidazole was blended instead of dicumyl peroxide. The gel time of these resin varnishes was measured in the same manner as described above. However, the measurement temperature was 200 ° C.
All evaluations other than gel time were performed using a resin varnish containing dicumyl peroxide or a resin molded product obtained from this resin varnish.

[Tension adhesive strength]
220 using a thermosetting molding material as an adhesive and a copper plate with a width of 10.0 mm, a length of 50.0 mm, and a thickness of 1.0 mm as an adherend in a method according to JIS K 6849: 1994. The tensile adhesive strength (N / mm ² ) of the product cured at ° C. for 2 hours was measured.

<Manufacturing of aldehyde group-containing resin>
[Synthesis Example 1]
(Reaction of orthohydroxybenzaldehyde with 4,4'-bis (methoxymethyl) biphenyl: molar ratio = 0.40)
850 g (6.967 mol) of orthohydroxybenzaldehyde, 674.5 g (2.787 mol) of 4,4'-bis (methoxymethyl) biphenyl in a 1 L reaction vessel equipped with a thermometer, a stirrer, and a cooling tube. 8.5 g of toluenesulfonic acid (1% with respect to orthohydroxybenzaldehyde) was charged, the temperature was raised to 160 ° C., and the reaction was carried out for 4 hours. Methanol produced by the reaction was removed from the system. After completion of the reaction, the reaction was neutralized and washed with water to remove unreacted orthohydroxybenzaldehyde to obtain an aldehyde-containing biphenyl resin. The softening point of the obtained resin was 81 ° C., and the melt viscosity at 150 ° C. was 1.2P. The mass average molecular weight (Mw) was 815 and the dispersity (Mw / Mn) was 1.48 by gel permeation chromatography analysis (hereinafter, sometimes abbreviated as GPC).

[Synthesis Example 2]
(Reaction of orthohydroxybenzaldehyde with para-xylene glycol dimethyl ether: molar ratio = 0.40)
850 g (6.967 mol) of orthohydroxybenzaldehyde, 462.6 g (2.787 mol) of paraxylene glycol dimethyl ether, 8.5 g of paratoluenesulfonic acid in a reaction vessel having a content of 1 L equipped with a thermometer, a stirrer, and a cooling tube. 1%) was charged with respect to orthohydroxybenzaldehyde, the temperature was raised to 160 ° C., and the reaction was carried out for 4 hours. Methanol produced by the reaction was removed from the system. After completion of the reaction, the reaction was neutralized and washed with water to remove unreacted orthohydroxybenzaldehyde to obtain an aldehyde-containing xylylene resin. The softening point of the obtained resin was 1.8 ° C., and the melt viscosity at 150 ° C. was 1.7P. The mass average molecular weight (Mw) by GPC was 756, and the dispersity (Mw / Mn) was 1.44.

<Manufacturing of allyl group-containing resin>
[Manufacturing Example 1]
(Reaction between aldehyde group-containing biphenyl resin and allylamine: denaturation rate of about 30 mol%)
100.0 g of the aldehyde-containing biphenyl resin obtained in Synthesis Example 1 was dissolved in 100.0 g of toluene, and the temperature was raised to 80 ° C. To this, 7.6 g of allylamine was added over 2 hours, paying attention to heat generation. Then, the temperature was raised to 150 ° C. while removing the used toluene under normal pressure, and aging was carried out for 3 hours. Methyl ethyl ketone (MEK) was added thereto so as to have a solid content of 60% to obtain an allyl group-containing resin A. The mass average molecular weight (Mw) by GPC was 2159, and the dispersity (Mw / Mn) was 2.39. ^The aldehyde group denaturation rate by ¹³ C-nuclear magnetic resonance analysis (hereinafter, also abbreviated as NMR) was 31 mol%.
The aldehyde group denaturation rate indicates the ratio of allyl groups to the total of aldehyde groups and allyl groups in the resin.

[Manufacturing Example 2]
(Reaction between aldehyde group-containing biphenyl resin and allylamine: denaturation rate of about 45 mol%)
100.0 g of the aldehyde-containing biphenyl resin obtained in Synthesis Example 1 was dissolved in 100.0 g of toluene, and the temperature was raised to 80 ° C. 11.4 g of allylamine was added thereto over 2 hours while paying attention to heat generation. Then, the temperature was raised to 150 ° C. while removing the used toluene under normal pressure, and aging was carried out for 3 hours. MEK was added thereto so as to have a solid content of 60% to obtain an allyl group-containing resin B. The mass average molecular weight (Mw) by GPC was 3105, and the dispersity (Mw / Mn) was 3.81. The aldehyde group denaturation rate by NMR was 44 mol%.

[Manufacturing Example 3]
(Reaction between aldehyde group-containing xylylene resin and allylamine: denaturation rate of about 30 mol%)
100.0 g of the aldehyde-containing xylylene resin obtained in Synthesis Example 2 was dissolved in 100.0 g of toluene, and the temperature was raised to 80 ° C. To this, 9.9 g of allylamine was added over 2 hours, paying attention to heat generation. Then, the temperature was raised to 150 ° C. while removing the used toluene under normal pressure, and aging was carried out for 3 hours. MEK was added thereto so as to have a solid content of 60% to obtain an allyl group-containing resin C. The mass average molecular weight (Mw) by GPC was 2311, and the dispersity (Mw / Mn) was 2.52. The aldehyde group denaturation rate by NMR was 32 mol%.

<Manufacturing of resin varnish and molded product (cured product)>
[Example 1]
To 166.7 g (resin content 100 g) of the allyl group-containing resin A, BMI-1000 (4,5'-diphenylmethanebismaleimide, maleimide equivalent 179 g / eq) manufactured by Daiwa Kasei Kogyo Co., Ltd .; hereinafter, "maleimide compound (1) ) ”) Was mixed in 19.2 g, and the reaction was carried out 5 hours before under reflux (95 ° C.). Then, 1.2 g of dicumyl peroxide and MEK were added so as to have a solid content of 60% to obtain a resin varnish A. The molar ratio (maleimide group / allyl group) of the maleimide group of the maleimide compound to the allyl group of the allyl group-containing resin was 1.0.
The resin varnish A was impregnated into a glass cloth (E glass) so as to have a resin content of 40%, and dried at 100 ° C. for 10 minutes to remove the solvent to obtain a prepreg. Six of these prepregs were stacked and press-molded at 200 ° C., and then after-baked at 220 ° C. for 2 hours to obtain a molded product A having a thickness of 1.5 mm.
The resin content indicates the ratio of the resin to the molded product A.

[Example 2]
166.7 g (resin content 100 g) of the allyl group-containing resin A and BMI-2300 (polyphenylmethane maleimide, maleimide equivalent 186 g / eq; hereinafter referred to as "maleimide compound (2)" manufactured by Daiwa Kasei Kogyo Co., Ltd. ) Was mixed, and the reaction was carried out 5 hours before under reflux (95 ° C.). Then, 1.2 g of dicumyl peroxide and MEK were added so as to have a solid content of 60% to obtain a resin varnish B. The molar ratio (maleimide group / allyl group) of the maleimide group of the maleimide compound to the allyl group of the allyl group-containing resin was 1.0. A molded product B having a thickness of 1.5 mm was obtained in the same manner as in Example 1 except that the resin varnish B was used instead of the resin varnish A.

[Example 3]
28.8 g of the maleimide compound (1) was mixed with 166.7 g (resin content 100 g) of the allyl group-containing resin B, and the reaction was carried out under reflux (95 ° C.) for 5 hours. Then, 1.3 g of dicumyl peroxide and MEK were added so as to have a solid content of 60% to obtain a resin varnish C. The molar ratio (maleimide group / allyl group) of the maleimide group of the maleimide compound to the allyl group of the allyl group-containing resin was 1.0.
A molded product C having a thickness of 1.5 mm was obtained in the same manner as in Example 1 except that the resin varnish C was used instead of the resin varnish A.

[Example 4]
20.1 g of the maleimide compound (1) was mixed with 166.7 g (resin content 100 g) of the allyl group-containing resin B, and the reaction was carried out under reflux (95 ° C.) for 5 hours. Then, 1.2 g of dicumyl peroxide and MEK were added so as to have a solid content of 60% to obtain a resin varnish D. The molar ratio (maleimide group / allyl group) of the maleimide group of the maleimide compound to the allyl group of the allyl group-containing resin was 0.7.
A molded product D having a thickness of 1.5 mm was obtained in the same manner as in Example 1 except that the resin varnish D was used instead of the resin varnish A.

[Example 5]
11.50 g of the maleimide compound (1) was mixed with 166.7 g (resin content 100 g) of the allyl group-containing resin B, and the reaction was carried out under reflux (95 ° C.) for 5 hours. Then, 1.1 g of dicumyl peroxide and MEK were added so as to have a solid content of 60% to obtain a resin varnish E. The molar ratio (maleimide group / allyl group) of the maleimide group of the maleimide compound to the allyl group of the allyl group-containing resin was 0.4.
A molded product E having a thickness of 1.5 mm was obtained in the same manner as in Example 1 except that the resin varnish E was used instead of the resin varnish A.

[Example 6]
29.9 g of the maleimide compound (2) was mixed with 166.7 g (resin content 100 g) of the allyl group-containing resin B, and the reaction was carried out under reflux (95 ° C.) for 5 hours. Then, 1.3 g of dicumyl peroxide and MEK were added so as to have a solid content of 60% to obtain a resin varnish F. The molar ratio (maleimide group / allyl group) of the maleimide group of the maleimide compound to the allyl group of the allyl group-containing resin was 1.0.
A molded product F having a thickness of 1.5 mm was obtained in the same manner as in Example 1 except that the resin varnish F was used instead of the resin varnish A.

[Example 7]
26.9 g of the maleimide compound (1) was mixed with 166.7 g (resin content 100 g) of the allyl group-containing resin C, and the reaction was carried out under reflux (95 ° C.) for 5 hours. Then, 1.3 g of dicumyl peroxide and MEK were added so as to have a solid content of 60% to obtain a resin varnish G. The molar ratio (maleimide group / allyl group) of the maleimide group of the maleimide compound to the allyl group of the allyl group-containing resin was 1.0.
A molded product G having a thickness of 1.5 mm was obtained in the same manner as in Example 1 except that the resin varnish G was used instead of the resin varnish A.

[Example 8]
27.9 g of the maleimide compound (2) was mixed with 166.7 g (resin content 100 g) of the allyl group-containing resin C, and the reaction was carried out under reflux (95 ° C.) for 5 hours. Then, 1.3 g of dicumyl peroxide and MEK were added so as to have a solid content of 60% to obtain a resin varnish H. The molar ratio (maleimide group / allyl group) of the maleimide group of the maleimide compound to the allyl group of the allyl group-containing resin was 1.0.
A molded product H having a thickness of 1.5 mm was obtained in the same manner as in Example 1 except that the resin varnish H was used instead of the resin varnish A.

[Comparative Example 1]
100 g of the following allyl group-containing resin D, 120.9 g of the maleimide compound (1), and 2.2 g of dicumyl peroxide were dissolved in methyl ethyl ketone to obtain a resin varnish I having a solid content of 60%. The molar ratio (maleimide group / allyl group) of the maleimide group of the maleimide compound to the allyl group of the allyl group-containing resin was 1.0.
Allyl group-containing resin D: Product name manufactured by Gun Ei Chemical Industry Co., Ltd .: XPL-4437E (allyl phenol formaldehyde resin). The allyl group-containing resin D was liquid at room temperature, and the viscosity at 25 ° C. was measured with an E-type viscometer and found to be 31 Pa · s.
A molded product I having a thickness of 1.5 mm was obtained in the same manner as in Example 1 except that the resin varnish I was used instead of the resin varnish A.

[Comparative Example 2]
100 g of the allyl group-containing resin D, 125.7 g of the maleimide compound (2), and 1.3 g of dicumyl peroxide were dissolved in methyl ethyl ketone to obtain a resin varnish J having a solid content of 60%. The molar ratio (maleimide group / allyl group) of the maleimide group of the maleimide compound to the allyl group of the allyl group-containing resin was 1.0.
A molded product J having a thickness of 1.5 mm was obtained in the same manner as in Example 1 except that the resin varnish J was used instead of the resin varnish A.

The glass transition temperature, 5% thermal decomposition temperature, room temperature linear expansion coefficient, relative permittivity, and dielectric loss tangent were measured for the molded articles A to J. In addition, the gel time and tensile adhesive strength of the resin varnish used in each molded product were measured. The results are shown in Tables 1-2.
Tables 1 and 2 also show the types of the allyl group-containing resin, the maleimide compound, and the curing reaction catalyst used in the resin moldings A to J, and the aldehyde group modification rate of the allyl group-containing resin.

The resin varnishes A to H of Examples 1 to 8 had a shorter gel time than the resin varnishes I to J of Comparative Examples 1 and 2. The same tendency was observed when the curing reaction catalyst was not included or when the type of curing reaction catalyst was changed. Further, the molded products A to H obtained from the resin varnishes A to H had stronger tensile adhesive strength and excellent adhesion than the molded products I to J obtained from the resin varnishes I to J. The relative permittivity and dielectric loss tangent were also low. Furthermore, the glass transition temperature, 5% thermal decomposition temperature, and normal temperature linear expansion rate were also sufficiently excellent.

According to this resin varnish, a cured product having a high glass transition temperature, a high thermal decomposition temperature, a low coefficient of linear thermal expansion, a low dielectric constant, a low dielectric loss tangent, and a high adhesion can be obtained in a short gel time. Therefore, this resin varnish is extremely useful as a highly functional polymer material, and as a thermally and electrically excellent material, a semiconductor encapsulation material, a resin material for encapsulating electronic parts, an electrically insulating material, and a copper-clad laminate. It can be used in a wide range of applications such as resin materials for use, build-up laminate materials, resist materials, resin materials for liquid crystal color filters, paints, various coating agents, adhesives, and FRP.

Claims (5)

It contains a maleimide compound having two or more maleimide groups, an allyl group-containing resin, and a solvent.
The allyl group-containing resin is represented by one or both of the structural unit (1) represented by the following formula (1) and the structural unit (2) represented by the following formula (2), and the following formula (3). It has a structural unit (3) represented by it and a structural unit (4) represented by the following formula (4).
The total content of the structural unit (2) and the structural unit (4) is the same as that of the structural unit (1), the structural unit (2), the structural unit (3), and the structural unit (4). Resin varnish which is 10 to 80 mol% based on the total.

[In the formula, Ar represents a benzene ring or a naphthalene ring, R represents a group represented by the following formula (r1) or (r2), p and q each independently represent 0 or 1, and − * and − ** indicates a bonder. -* Bonds to another structural unit, and-(R) _p -**-** binds to another structural unit or hydrogen atom when p is 0, and when p is 1. Is bonded to another structural unit, and-(R) _q -**-** is bonded to another structural unit or hydrogen atom when q is 0, and other when q is 1. Combine into building blocks. ]

The resin varnish according to claim 1, wherein the molar ratio (maleimide group / allyl group) of the maleimide group of the maleimide compound to the allyl group of the allyl group-containing resin is 0.2 to 1.4. A method for producing a resin varnish by mixing a maleimide compound having two or more maleimide groups, an allyl group-containing resin, and a solvent.
The allyl group-containing resin is represented by one or both of the structural unit (1) represented by the following formula (1) and the structural unit (2) represented by the following formula (2), and the following formula (3). It has a structural unit (3) represented by it and a structural unit (4) represented by the following formula (4).
The total content of the structural unit (2) and the structural unit (4) is the same as that of the structural unit (1), the structural unit (2), the structural unit (3), and the structural unit (4). A method for producing a resin varnish, which is 10 to 80 mol% of the total.

[In the formula, Ar represents a benzene ring or a naphthalene ring, R represents a group represented by the following formula (r1) or (r2), p and q each independently represent 0 or 1, and − * and − ** indicates a bonder. -* Bonds to another structural unit, and-(R) _p -**-** binds to another structural unit or hydrogen atom when p is 0, and when p is 1. Is bonded to another structural unit, and-(R) _q -**-** is bonded to another structural unit or hydrogen atom when q is 0, and other when q is 1. Combine into building blocks. ]

The method for producing a resin varnish according to claim 3, wherein after the mixing, the maleimide compound and the allyl group-containing resin are prereacted. A method for producing a laminated board, wherein the fibrous base material is impregnated with the resin varnish according to claim 1 or 2, and the fibrous base material impregnated with the resin varnish is heated and pressed to be cured to obtain a laminated board.