JP2024026969A - Method for producing varnish, method for producing prepreg, method for producing resin film, and method for producing laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a varnish that prepares a slurry with high redispersibility through a process that enables the slurrification of high dielectric constant materials, and can suppress generation of aggregates by using the slurry, and to provide a method for producing a prepreg, a method for producing a resin film and a method for producing a laminate, each of which utilizes the method for producing the varnish.

SOLUTION: The present invention provides a method for producing a varnish that comprises (A) 100 pts.mass of thermosetting resin, (B) 50 to 400 pts.mass of at least one inorganic filler selected from the group consisting of titanium inorganic fillers and zircon inorganic fillers, (C) 20 to 300 pts.mass of particles with its average particle size smaller than the average particle size of the component (B), and an organic solvent. The method for producing the varnish includes dispersing the component (B) in liquid along with the component (C) to prepare slurry, which is then mixed with 80 pts.mass or more of 100 pts.mass of the thermosetting resin (A), thereby producing the varnish.

SELECTED DRAWING: None

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present disclosure relates to a method for manufacturing a varnish, a method for manufacturing a prepreg, a method for manufacturing a resin film, and a method for manufacturing a laminate.

In recent years, as mobile terminals such as smartphones have become widespread, and technological innovations such as IoT (Internet of Things) have progressed, the number of home appliances and electronic devices having wireless communication functions is increasing. There are concerns that this will increase the communication traffic of wireless networks and reduce communication speed and communication quality.
In order to solve this problem, a fifth generation mobile communication system (hereinafter sometimes referred to as "5G") is being developed and is already being used. In 5G, multiple antenna elements are used to perform advanced beamforming and spatial multiplexing, and in addition to the conventionally used 6GHz frequency signals, higher frequency millimeter wave bands of several tens of GHz will be used. use the signal. This is expected to increase communication speed and improve communication quality. Hereinafter, frequencies of 10 GHz and above will be referred to as high frequencies.

In this way, in 5G, the antenna module needs to be able to handle high frequency signals, and for this purpose, the dielectric loss tangent (Df) of the laminate is required to be low in the high frequency band.
Since high-frequency radio waves have high linearity, signals carried on high-frequency radio waves tend to be easily blocked by obstacles such as buildings. Therefore, in order to avoid this interruption, a plurality of antenna devices are mounted on the antenna module. The antenna device can be made smaller by increasing the dielectric constant (Dk) of the substrate material, so increasing the dielectric constant (Dk) is effective for mounting multiple antenna devices, and also reduces the size of the antenna module. This also leads to miniaturization of communication devices. Therefore, a laminate used in an antenna module capable of handling high-frequency signals is required to have a relative dielectric constant (Dk) of a predetermined height and a low dielectric loss tangent (Df).

Here, one method of increasing the dielectric constant (Dk) of the substrate material is to use a high dielectric constant material (for example, see Patent Document 1). The small antenna described in Patent Document 1 is manufactured by laminating and sandwiching a first dielectric layer made of a low dielectric constant material with second and third dielectric layers made of a high dielectric constant material. .

International Publication No. 2005/101574

When the present inventors attempted to prepare a varnish made of a thermosetting resin composition containing a high dielectric constant material, it was found that aggregates were likely to occur in the varnish, and as a result, the appearance of the cured product could be impaired. There was found. Therefore, the present inventors speculated that the aggregates were caused by the high dielectric constant material, and the high dielectric constant material was dispersed in a liquid to form a slurry, and then mixed with other components. When they prepared the varnish, they found that it was difficult to make a high dielectric constant material into a slurry, and it was not easy to solve the problem of aggregates in the varnish. Here, in the present disclosure, a state in which solid particles are dispersed or suspended in a liquid is referred to as "slurrying", and the state in which solid particles are dispersed or suspended is referred to as a "slurry". Note that if aggregates are generated in the varnish, the appearance of the cured product will be poor, and it may lead to a decrease in insulation reliability.
Further, as a result of further investigation by the present inventors, it was found that even in a slurry in which generation of aggregates was suppressed, aggregates could occur when left for several days. In industrial practice, there are embodiments in which the slurry is allowed to stand for several days before being used. Therefore, it is required that the dispersibility of the solid content after the slurry is allowed to stand for several days (hereinafter referred to as redispersibility) is good.

In view of the current situation, the present disclosure provides a method for preparing a slurry with good redispersibility using a method that enables slurrying of high dielectric constant materials, and by using the slurry, generation of aggregates can be suppressed. It is an object of the present invention to provide a method for producing varnish, and to provide a method for producing prepreg, a method for producing resin film, and a method for producing laminate using the production method.

As a result of intensive research, the present inventors have found that the above object can be achieved using the manufacturing method of the present disclosure.

The present disclosure includes the embodiments [1] to [13] below.
[1] (A) 100 parts by mass of a thermosetting resin, (B) 50 to 400 parts by mass of at least one inorganic filler selected from the group consisting of titanium-based inorganic fillers and zircon-based inorganic fillers, (C ) A method for producing a varnish comprising 20 to 300 parts by mass of particles having an average particle diameter smaller than the average particle diameter of the component (B) and an organic solvent,
Prepare a slurry by dispersing the component (B) together with the component (C) in a liquid, and then mix it with 80 parts by mass or more of 100 parts by mass of the thermosetting resin (A) to form a varnish. ,
A method of manufacturing a varnish, including:
[2] The method for producing a varnish according to [1] above, wherein the average particle diameter of the component (C) is 0.3 μm or more smaller than the average particle diameter of the component (B).
[3] The method for producing a varnish according to [1] or [2] above, wherein the average particle diameter of the component (B) is 0.1 to 4.0 μm.
[4] When preparing a slurry by dispersing the (B) component together with the (C) component in a liquid, adding and mixing the (B) component to the slurry in which the (C) component is dispersed. The method for producing a varnish according to any one of [1] to [3] above, comprising:
[5] When preparing a slurry by dispersing the (B) component together with the (C) component in a liquid, (A ) The above [[ The method for producing a varnish according to any one of [1] to [4].
[6] The method for producing a varnish according to any one of [1] to [5] above, wherein the titanium-based inorganic filler is at least one selected from the group consisting of titanium dioxide and metal titanate.
[7] Production of the varnish according to [6] above, wherein the metal titanate is at least one selected from the group consisting of an alkali metal titanate, an alkaline earth metal titanate, and a lead titanate. Method.
[8] The method for producing a varnish according to any one of [1] to [7] above, wherein the zircon-based inorganic filler is an alkali metal zirconate salt.
[9] The method for producing a varnish according to any one of [1] to [8] above, wherein the component (C) contains at least one selected from the group consisting of an inorganic filler and a flame retardant.
[10] The method for producing a varnish according to any one of [1] to [9] above, wherein the liquid contains a ketone solvent.
[11] A prepreg manufacturing method comprising impregnating or coating a sheet-like fiber base material with the varnish obtained by the manufacturing method according to any one of [1] to [10] above, and then drying the varnish.
[12] A method for producing a resin film, comprising applying a varnish obtained by the production method according to any one of [1] to [10] above to a support and then drying the varnish.
[13] A metal foil is placed on one or both sides of a prepreg obtained by stacking two or more prepregs obtained by the manufacturing method described in [11] above, or a total of two sheets of the prepreg and another prepreg are arranged. A method for producing a laminate, the method comprising placing a metal foil on one or both sides of the prepreg obtained by stacking the above, followed by heating and pressure forming.

The present disclosure provides a method for producing a varnish that can suppress the generation of aggregates by preparing a slurry with good redispersibility using a method that enables slurrying of a high dielectric constant material, and using the slurry. In addition, it is possible to provide a prepreg manufacturing method, a resin film manufacturing method, and a laminate manufacturing method using the manufacturing method.

In the numerical range of the present disclosure, the upper limit or lower limit of the numerical range may be replaced with the values shown in the examples. Further, the lower limit value and upper limit value of the numerical range can be arbitrarily combined with the lower limit value or upper limit value of other numerical ranges, respectively. In the notation of a numerical range "AA to BB", the numerical values AA and BB at both ends are included in the numerical range as the lower limit value and upper limit value, respectively.
In this disclosure, for example, the description "10 or more" means 10 and a numerical value exceeding 10, and this applies even if the numerical values are different. Further, for example, the description "10 or less" means a numerical value of 10 and less than 10, and this applies even if the numerical values are different.
Further, each of the components and materials exemplified in the present disclosure may be used alone or in combination of two or more, unless otherwise specified. In the present disclosure, if there are multiple substances corresponding to each component in the composition, unless otherwise specified, the content of each component in the composition refers to the total amount of the multiple substances present in the composition. means.

In the present disclosure, the term "resin component" refers to all components of the solid content constituting the resin composition, excluding inorganic compounds such as inorganic fillers described below.
In the present disclosure, "solid content" refers to components other than the organic solvent in the resin composition. That is, the solid content includes those that are solid at room temperature around 25°C, as well as those that are liquid, starch syrup-like, or wax-like at room temperature around 25°C.
In the present disclosure, the expression "contains XX" may refer to containing XX in a reacted state when XX can react, or may simply contain XX as it is, or may include both of these. This aspect may also be included.
Aspects in which the items described in this disclosure are arbitrarily combined are also included in this disclosure and this embodiment.

[Varnish manufacturing method]
The method for manufacturing the varnish of this embodiment is as follows.
(A) 100 parts by mass of a thermosetting resin, (B) 50 to 400 parts by mass of at least one inorganic filler selected from the group consisting of titanium-based inorganic fillers and zircon-based inorganic fillers, (C) the above ( B) A method for producing a varnish containing 20 to 300 parts by mass of particles having an average particle diameter smaller than the average particle diameter of component and an organic solvent,
Prepare a slurry by dispersing the component (B) together with the component (C) in a liquid, and then mix it with 80 parts by mass or more of 100 parts by mass of the thermosetting resin (A) to form a varnish. ,
A method of manufacturing a varnish, including:
In the present disclosure, varnish refers to a thermosetting resin composition containing an organic solvent and having a resin component concentration of 40% by mass or more. On the other hand, the concentration of the resin component in the slurry prepared by dispersing the component (B) together with the component (C) in a liquid is 0 to 10% by mass, preferably 0 to 8% by mass, more preferably It is 0 to 6% by mass. The lower limit of the concentration of the resin component in the slurry may be 0.1% by mass, 0.5% by mass, 1.5% by mass, or 3% by mass. It may be %.
Note that the component (B) corresponds to the above-mentioned high dielectric constant material.

As mentioned above, even if it is desired to slurry the component (B) before preparing the varnish in order to suppress the agglomeration of the component (B) in the varnish, the component (B) It is difficult to make slurry alone. One of the reasons for this is considered to be that the component (B) is generally a substance that is difficult to surface treat. Based on this, in the present embodiment, the component (B) is slurried together with the component (C), which is "particles having an average particle diameter smaller than the average particle diameter of the component (B)". Adopt a method. The exact reason why component (B), which is difficult to slurry on its own, became possible when combined with component (C) is unknown, but component (B) has a larger average particle size than component (C). It is inferred that the dispersibility of component (B) was greatly increased by entering the small component (C). By mixing a slurry containing the component (B) and the component (C) with the component (A) and, if necessary, an organic solvent and other components described below, the dispersibility of the component (B) in the varnish can be improved. It is presumed that this resulted in the effective suppression of the formation of aggregates in the varnish mixed with a predetermined amount or more of the thermosetting resin.
However, even if the above speculation is not necessarily correct, this does not affect the scope of this embodiment.

The liquid used when forming a slurry by dispersing the component (B) together with the component (C) in a liquid is not particularly limited, but includes the below-mentioned organic solvents that can be contained in the varnish. From the viewpoint of dispersibility of component (B) and component (C), the liquid preferably contains a ketone solvent, and more preferably contains methyl isobutyl ketone.
The solid content concentration of the slurry containing the (B) component and the (C) component [solid content concentration that is not limited to the (B) component and (C) component but also includes other solid content that the slurry may contain] is: Although not particularly limited, mainly from the viewpoint of the dispersibility of the component (B) and the component (C) and the fluidity of the slurry, preferably 55 to 80% by mass, more preferably 60 to 75% by mass. , more preferably 65 to 72% by mass.
Further, the content ratio [(B)/(C)] of the (B) component and the (C) component in the slurry containing the (B) component and the (C) component is not particularly limited. From the viewpoint of dispersibility of the component (B), the mass ratio is preferably 90/10 to 50/50, more preferably 85/15 to 55/45, and even more preferably 80/20 to 60/40. .

In this embodiment, although not particularly limited, when preparing a slurry by dispersing the component (B) together with the component (C) in a liquid, that is, the component (B) and the component (C) When preparing a slurry containing the components, it is preferable to add and mix the component (B) to the slurry in which the component (C) is dispersed. In this case, the solid content concentration of the slurry in which the component (C) is dispersed is preferably 55 to 90% by mass, more preferably from the viewpoint of the dispersibility of the component (C) and the fluidity of the slurry containing the component (C). is 60 to 85% by weight, more preferably 65 to 75% by weight.
As a method of adding and mixing the component (B) to the slurry in which the component (C) is dispersed, the component (B) is added all at once to the slurry in which the component (C) is dispersed and mixed. Alternatively, the mixture may be added in two or more portions and mixed.
The mixing method is not particularly limited, but includes a method of mixing component (B) and component (C) using at least one selected from the group consisting of a stirrer and a mixer. . Examples of the stirrer or mixer include a motor stirrer, an air stirrer, a planetary mixer, a sanitary mixer, and a revolution mixer.

Note that when dispersing the component (B) together with the component (C) in a liquid, the thermosetting resin (A) and the D) Preferably, 1 to 10 parts by mass of at least one selected from the group consisting of thermoplastic resins is dispersed in the liquid together with the component (B) and the component (C). Thus, by incorporating the above amount of thermosetting resin or the above amount of thermoplastic resin into the slurry containing the component (B) and the component (C), the redispersibility of the slurry tends to be improved. be. The good redispersibility of the slurry makes it possible to use the slurry after redispersing the component (B), etc. in the slurry after it has been allowed to stand for several days, which makes it possible to adopt the above embodiment. Industrially useful.
Specifically, the content of the thermosetting resin or thermoplastic resin contained in the slurry containing the component (B) and the component (C) is 100 mass of the total of the component (B) and the component (C). 1 to 10 parts by weight, preferably 2 to 8 parts by weight, and more preferably 3 to 7 parts by weight.
The above amount of thermosetting resin or the above amount of thermoplastic resin may be added and mixed after preparing the slurry containing the above (B) component and the above (C) component, or the above (C) component may be dispersed. When adding and mixing the (B) component to the slurry, the above amount of (A) thermosetting resin or the above amount of (D) thermoplastic resin is added and mixed together with the (B) component. Good too.
In addition, the above amount of (A) thermosetting resin or the above amount of (D) thermoplastic resin is added and mixed to the slurry in which the above (C) component is dispersed, and the above (B) component is added thereto. Alternatively, another component (C) may be added and mixed after that.

Furthermore, the slurry containing the component (B) and the component (C) may contain a surface treatment agent (E), which will be described later. By incorporating the surface treatment agent (E) into the slurry, the redispersibility of the slurry may be improved. The surface treatment agent (E) to be included in the slurry is as described below, but from the viewpoint of redispersibility of the slurry, in particular, a silane coupling agent having no tertiary amino group, a tertiary amino Titanate coupling agents without groups are preferred. Silane coupling agents that do not have a tertiary amino group include, but are not limited to, 3-glycidoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, N-phenyl-3-amino Preferably, it is a trialkoxysilane without a tertiary amino group, such as propyltrimethoxysilane. The titanate coupling agent that does not have a tertiary amino group is preferably a phosphoric acid-modified titanate that does not have a tertiary amino group, or a terminal long chain alkyl fatty acid modified titanate that does not have a tertiary amino group. . The long chain alkyl fatty acid of the terminal long chain alkyl fatty acid modified titanate that does not have a tertiary amino group is preferably a fatty acid with 8 or more carbon atoms, more preferably a fatty acid with 12 to 30 carbon atoms, A fatty acid having 14 to 24 carbon atoms is more preferable, and a fatty acid having 14 to 20 carbon atoms is particularly preferable. Specific examples of the long chain alkyl fatty acid of the terminal long chain alkyl fatty acid modified titanate having no tertiary amino group include -O-(C=O)-C ₁₇ H ₃₅ and the like.
The content of the surface treatment agent (E) to be contained in the slurry containing the component (B) and the component (C) is the sum of the component (B) and the component (C) from the viewpoint of redispersibility of the slurry. The amount is 0.05 to 5 parts by weight, preferably 0.1 to 3 parts by weight, and more preferably 0.5 to 2 parts by weight per 100 parts by weight.

Each component used in the manufacturing method of this embodiment will be described in detail below.
((A) Thermosetting resin)
(A) Components include epoxy resin, maleimide compound, modified polyphenylene ether resin, phenol resin, polyimide resin, cyanate resin, isocyanate resin, benzoxazine resin, oxetane resin, amino resin, unsaturated polyester resin, allyl resin, dicyclo Examples include pentadiene resin, silicone resin, triazine resin, and melamine resin. Among these, component (A) used in the production of varnish is preferably an epoxy resin, a maleimide compound, or a modified polyphenylene ether resin, and from the viewpoint of low thermal expansion and heat resistance, it is an epoxy resin or a maleimide compound. is more preferred, and maleimide compounds and modified polyphenylene ether resins are more preferred from the viewpoint of low thermal expansion, dielectric loss tangent (Df), and the like. In addition, from the viewpoint of redispersibility, the thermosetting resin (A) to be contained when dispersing the component (B) together with the component (C) in a liquid to form a slurry should be an epoxy resin or a maleimide compound. is preferred, and epoxy resin is more preferred.
Component (A) may be used alone or in combination of two or more.

The epoxy resin preferably has two or more epoxy groups in one molecule. Here, the epoxy resin is classified into glycidyl ether type epoxy resin, glycidyl amine type epoxy resin, glycidyl ester type epoxy resin, and the like. Among these, glycidyl ether type epoxy resins are preferred.
Epoxy resins are classified into various epoxy resins depending on the main skeleton, and in each of the above types of epoxy resins, there are also bisphenol type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, etc. Epoxy resin; alicyclic epoxy resin such as dicyclopentadiene epoxy resin; aliphatic chain epoxy resin; phenol novolak epoxy resin, cresol novolac epoxy resin, bisphenol A novolak epoxy resin, bisphenol F novolak epoxy resin, Novolac type epoxy resins such as phenol aralkyl novolac type epoxy resins and biphenylaralkyl novolac type epoxy resins; stilbene type epoxy resins; naphthalene skeleton-containing epoxy resins such as naphthol novolak type epoxy resins, naphthol cresol novolak type epoxy resins, naphthol aralkyl type epoxy resins It is classified into resins; biphenylaralkyl-type epoxy resins; xylylene-type epoxy resins; dihydroanthracene-type epoxy resins, etc.
In addition, when the component (A) used in the production of the varnish is an epoxy resin, the epoxy resin must be a naphthalene skeleton-containing epoxy resin from the viewpoint of high elastic modulus, high glass transition temperature, and low water absorption. is preferred. If the component (A) to be contained when dispersing the component (B) together with the component (C) into a liquid to form a slurry is an epoxy resin, from the viewpoint of redispersibility, the epoxy resin should have a naphthalene skeleton. Preferably, it is a containing type epoxy resin.

The maleimide compound preferably contains at least one selected from the group consisting of maleimide compounds having one or more (preferably two or more) N-substituted maleimide groups and derivatives thereof; It is more preferable to include a derivative of a maleimide compound having 1 or more (preferably 2 or more).
Maleimide compounds having one or more N-substituted maleimide groups include, but are not particularly limited to, N-phenylmaleimide, N-(2-methylphenyl)maleimide, N-(4-methylphenyl)maleimide, N- -(2,6-dimethylphenyl)maleimide, N-(2,6-diethylphenyl)maleimide, N-(2-methoxyphenyl)maleimide, N-benzylmaleimide, etc., preferably one N- bonded to the aromatic ring Aromatic maleimide compounds having substituted maleimide groups; bis(4-maleimidophenyl)methane, bis(4-maleimidophenyl)ether, bis(4-maleimidophenyl)sulfone, 3,3'-dimethyl-5,5'-diethyl -4,4'-diphenylmethane bismaleimide, 4-methyl-1,3-phenylenebismaleimide, m-phenylenebismaleimide, 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane, indane ring-containing bis Aromatic bismaleimide compounds preferably having two N-substituted maleimide groups bonded to an aromatic ring, such as maleimide; preferably three or more N-substituted maleimide groups bonded to an aromatic ring, such as polyphenylmethane maleimide, biphenylaralkyl maleimide, etc. Aromatic polymaleimide compound having a maleimide group; N-dodecylmaleimide, N-isopropylmaleimide, N-cyclohexylmaleimide, 1,6-bismaleimide-(2,2,4-trimethyl)hexane, pyrrolilonate binder type long chain alkyl Examples include aliphatic maleimide compounds such as bismaleimide. Among these, from the viewpoint of compatibility with other resins, adhesion with conductors, heat resistance, low thermal expansion, and mechanical properties, aromatic compounds having two N-substituted maleimide groups bonded to aromatic rings are preferred. Bismaleimide compounds are more preferred, and 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane is even more preferred.

In addition, as a derivative of a maleimide compound, an addition reaction product (hereinafter referred to as a "modified product") of a maleimide compound having one or more (preferably two or more) N-substituted maleimide groups and an amine compound such as a monoamine compound or a diamine compound is used. (sometimes referred to as "maleimide compounds").
The monoamine compounds include o-aminophenol, m-aminophenol, p-aminophenol, o-aminobenzoic acid, m-aminobenzoic acid, p-aminobenzoic acid, o-aminobenzenesulfonic acid, m-aminobenzene. Examples include monoamine compounds having acidic substituents such as sulfonic acid, p-aminobenzenesulfonic acid, 3,5-dihydroxyaniline, and 3,5-dicarboxyaniline. The diamine compounds include 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane, 4,4'-diaminodiphenylpropane, 2,2'-bis(4,4'-diaminodiphenyl)propane, 3 , 3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-diethyl-4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylethane, 3,3'- Diethyl-4,4'-diaminodiphenylethane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylthioether, 3,3'-dihydroxy-4,4'-diaminodiphenylmethane, 2,2',6, 6'-tetramethyl-4,4'-diaminodiphenylmethane, 3,3'-dichloro-4,4'-diaminodiphenylmethane, 3,3'-dibromo-4,4'-diaminodiphenylmethane, 2,2',6 , 6'-tetrachloro-4,4'-diaminodiphenylmethane, 2,2',6,6'-tetrabromo-4,4'-diaminodiphenylmethane, etc., in which an amino group is bonded to an aromatic hydrocarbon group. Aromatic diamines; siloxane diamines and the like.
The maleimide compound preferably includes an addition reaction product of a maleimide compound having two or more N-substituted maleimide groups and an amine compound, and a maleimide compound having two or more N-substituted maleimide groups and a diamine containing siloxane diamine. It is more preferable to include an addition reaction product with the compound.
The weight average molecular weight (Mn) of the maleimide compound is not particularly limited, but is preferably 400 to 10,000, more preferably 1,000 to 5,000, and still more preferably 1,500 to 4,000. In the present disclosure, weight average molecular weight (Mw) means a value measured in terms of polystyrene by gel permeation chromatography (GPC).

The modified polyphenylene ether resin may be a polyphenylene ether resin having an ethylenically unsaturated bond-containing group at the end. The polyphenylene ether resin having an ethylenically unsaturated bond-containing group at the end is preferably a polyphenylene ether resin having an ethylenically unsaturated bond-containing group at both ends. Here, the "ethylenic unsaturated bond-containing group" means a substituent containing a carbon-carbon double bond capable of an addition reaction, and does not include a double bond in an aromatic ring. The ethylenically unsaturated bond-containing group includes unsaturated aliphatic hydrocarbon groups such as vinyl group, allyl group, 1-methylallyl group, isopropenyl group, 2-butenyl group, 3-butenyl group, and styryl group; maleimide group , a group containing a hetero atom and an ethylenically unsaturated bond such as a (meth)acryloyl group, and the like. The ethylenically unsaturated bond-containing group is preferably a group containing a hetero atom and an ethylenically unsaturated bond, more preferably a (meth)acryloyl group, and even more preferably a methacryloyl group.
In addition, in this disclosure, a "(meth)acryloyl group" means an acryloyl group or a methacryloyl group.

(Amount of component (A) to be mixed during varnish preparation after slurrying)
In the manufacturing method of the present embodiment, after the component (B) is dispersed in a liquid together with the component (C) to form a slurry, 80 parts by mass or more (100 parts by mass) of 100 parts by mass of the thermosetting resin (A) is prepared. (parts by weight). The amount of the thermosetting resin (A) to be mixed when preparing the varnish after slurrying is when the thermosetting resin (A) is added to the slurry containing the component (B) and the component (C). is equivalent to the amount minus the amount used. In other words, if the slurry containing the component (B) and the component (C) does not contain the thermosetting resin (A), 100 parts by mass of the thermosetting resin (A) is used when preparing the varnish. For example, when the slurry containing the component (B) and the component (C) contains 5 parts by mass of the thermosetting resin (A), the thermosetting resin (A) is added to the slurry containing the component (B) and the component (C). 95 parts by mass of resin will be used.
After the component (B) is dispersed into a liquid together with the component (C) to form a slurry, it is mixed with 85 parts by mass or more (including 100 parts by mass) of the 100 parts by mass of the thermosetting resin (A). It is preferable to prepare a varnish, and it is more preferable to prepare a varnish by mixing it with 90 parts by mass or more (including 100 parts by mass) of 100 parts by mass of the thermosetting resin (A).

((B) At least one inorganic filler selected from the group consisting of titanium-based inorganic fillers and zircon-based inorganic fillers)
From the viewpoint of dielectric constant (Dk), the titanium-based inorganic filler is preferably at least one selected from the group consisting of titanium dioxide and metal titanate. From the viewpoint of dielectric constant (Dk), the titanate metal salts include alkali metal titanates such as potassium titanate; alkaline earth metal titanates such as barium titanate, calcium titanate, and strontium titanate; Examples include lead titanate. The metal titanate is preferably at least one selected from these examples, more preferably an alkaline earth metal titanate from the viewpoint of dielectric constant (Dk), and calcium titanate. , more preferably strontium titanate, and particularly preferably calcium titanate.
The zircon-based inorganic filler is preferably an alkali metal zirconate salt from the viewpoint of dielectric constant (Dk). The alkali metal zirconate salt is preferably at least one selected from the group consisting of calcium zirconate and strontium zirconate from the viewpoint of dielectric constant (Dk).
Component (B) is preferably a titanium-based inorganic filler from the viewpoint of dielectric loss tangent (Df) and specific gravity, and more preferable ones are as described above.

The average particle diameter of component (B) is not particularly limited, but is preferably 0.1 μm or more, more preferably 0.4 μm or more, and from the viewpoint of heat resistance, 1.0 μm or more. It is more preferable that it is, and it is especially preferable that it is 1.5 μm or more. The upper limit of the average particle diameter of component (B) is preferably 4.0 μm or less, more preferably 3.5 μm or less, from the viewpoint of eliminating coarse particles that may cause insulation defects. It is more preferably 0 μm or less, and particularly preferably 2.5 μm or less.
From the above, the average particle diameter of component (B) is preferably 0.1 to 4.0 μm, and the lower limit and upper limit in this numerical range can be changed based on the above description.
Here, in the present disclosure, the average particle diameter refers to the average primary particle diameter.
In addition, by using two types of (B) components with different average particle diameters, the other (B) component, which has a smaller average particle diameter than the average particle diameter of one (B) component, can substitute for the (C) component. When we investigated whether or not this would become a component, we found that in this case, the redispersibility of the slurry would be extremely poor (see Comparative Examples 4 and 5).
In the present disclosure, the average particle diameter is the d50 value (median diameter of volume distribution) in the particle size distribution measured by a particle size distribution measuring device. The method and conditions for measuring the average particle diameter may be in accordance with the methods described in Examples.

(B) There is no particular restriction on the shape of the component, but since industrially available products are generally irregular in shape, it may be irregular in shape, but other shapes such as spherical are also acceptable. It's okay.

(Content of component (B) in varnish)
In the manufacturing method of the present embodiment, the content of component (B) in the varnish is not particularly limited, but from the viewpoint of dielectric constant (Dk), the content of component (A) is as follows: 50 to 400 parts by mass, preferably 70 to 350 parts by mass, more preferably 100 to 300 parts by mass, even more preferably 110 to 290 parts by mass, and 120 to 280 parts by mass. It may be 130 to 270 parts by mass, 140 to 260 parts by mass, 150 to 250 parts by mass, or 120 to 140 parts by mass. The amount may be from 160 to 180 parts by mass, or from 270 to 290 parts by mass. Here, the content of component (B) in the varnish also includes the amount of component (B) in the slurry.
If the amount of the component (B) used is at least the lower limit value, it tends to be possible to sufficiently increase the dielectric constant (Dk), and if it is at least the upper limit value, the dielectric loss tangent (Df) also increases. There is a tendency to be able to control excess.

((C) Particles having an average particle diameter smaller than the average particle diameter of the component (B))
In the manufacturing method of this embodiment, as described above, particles having an average particle diameter smaller than the average particle diameter of the component (B) are used as the component (C). Component (C) may be used alone or in combination of two or more types, but from the viewpoint of dispersibility of component (B), it is preferable to use two or more types in combination. .
The average particle size of the component (C) is preferably smaller than the average particle size of the component (B) by 0.3 μm or more, and preferably 0.5 μm or more smaller than the average particle size of the component (B) from the viewpoint of the dispersibility of the component (B). More preferably, it is smaller by 1.0 μm or more, and even more preferably by 1.3 μm or more.

The material of the component (C) is different from the material of the component (B). Component (C) is not particularly limited, but preferably contains at least one selected from the group consisting of an inorganic filler and a flame retardant, more preferably an inorganic filler and a flame retardant. The inorganic filler is preferably an inorganic filler other than titanium-based inorganic fillers and zircon-based inorganic fillers, and examples of such inorganic fillers include silica, alumina, mica, beryllia, aluminum carbonate, and hydroxide. Magnesium, aluminum hydroxide, aluminum silicate, calcium carbonate, calcium silicate, magnesium silicate, silicon nitride, boron nitride, clay such as calcined clay, molybdate compounds such as zinc molybdate, talc, aluminum borate, silicon carbide etc. Among these, silica, alumina, mica, and talc are preferred, silica and alumina are more preferred, and silica is even more preferred from the viewpoint of low thermal expansion, elastic modulus, heat resistance, and flame retardancy. Examples of the silica include crushed silica, fumed silica, and fused silica. Among these, fused silica is preferred, and fused spherical silica is more preferred.
The average particle diameter of the inorganic filler is preferably 0.1 to 5 μm, more preferably 0.1 to 1.5 μm, even more preferably 0.2 to 1.0 μm, and particularly preferably 0.3 to 0.8 μm. .

Further, the flame retardant is preferably a flame retardant that does not dissolve in the liquid in the slurry of component (C). Whether or not it dissolves in the liquid is determined by visually checking the state when 50 parts by mass of the flame retardant is added to 100 parts by mass of the liquid and stirred at 25° C. for 30 minutes. If no precipitate is generated, it is determined to be "dissolved", and if a precipitate is generated, it is determined to be "not dissolved". The flame retardant that does not dissolve in the liquid in the slurry of component (C) is not particularly limited as long as it does not dissolve in the liquid in the slurry of component (C), and any known flame retardant can be used. The flame retardant is selected from the group consisting of (C1) a phosphate compound, (C2) a phosphine oxide compound, and (C3) a phosphaphenanthrene compound, (C4) a metal salt of phosphinic acid, and (C5) an organic nitrogen-containing phosphorus compound. It is preferable that at least one type of phosphate compound (C1) is included, and it is more preferable that a phosphate compound (C1) is included.
The average particle diameter of the flame retardant is preferably 0.1 to 5 μm, more preferably 0.5 to 3.5 μm, even more preferably 1.0 to 2.5 μm, and particularly preferably 1.0 to 2.0 μm.

((C1) Phosphate compound)
The phosphate compounds may be used alone or in combination of two or more. As the phosphate compound, commercially available products can be used.
The component (C1) preferably has two or more phosphate groups in its molecule, more preferably two phosphate groups in its molecule. Here, the phosphate group is a group represented by the following formula.

(* indicates the bonding position.)

The phosphate compound having two or more phosphate groups in the molecule preferably has a linking group that connects the two or more phosphate groups. Examples of the linking group include, but are not limited to, a phenylene group, a xylylene group, a biphenylene group, a naphthylene group, a methylene group, an ethylene group, and the like. From the viewpoint of component (C1) having a high melting point, the linking group preferably contains at least one selected from the group consisting of a phenylene group, a xylylene group, a biphenylene group, and a naphthylene group, and preferably contains a phenylene group. More preferred.

From the viewpoint of flame retardancy, the oxygen atom contained in the phosphate group may be substituted in the aromatic ring.
From the viewpoint of flame retardancy, component (C1) is preferably a compound represented by the following general formula (C1-1).

(In the formula, R ^c1 to R ^c4 each independently represent an aliphatic hydrocarbon group having 1 to 5 carbon atoms. ^{Z c1} is a divalent group represented by the following general formula (C1-2) or Represents a divalent fused polycyclic aromatic hydrocarbon group. ^{n c1} to n ^c4 each independently represent an integer of 0 to 5, and n ^c5 represents an integer of 0 to 5.)

(In the formula, R ^c5 and R ^c6 each independently represent an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom. Z ^c2 represents an alkylene group having 1 to 5 carbon atoms, an alkylene group having 2 to 5 carbon atoms, represents an alkylidene group, -O-, -S-, a sulfonyl group, a carbonyloxy group, a keto group, or a single bond. n ^c6 and n ^c7 each independently represent an integer of 0 to 4. n ^c8 is (Indicates an integer from 1 to 3.)

The aliphatic hydrocarbon groups having 1 to 5 carbon atoms represented by R ^c1 to R ^c4 in the general formula (C1-1) include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, Examples include isobutyl group, t-butyl group, n-pentyl group and the like. The aliphatic hydrocarbon group is preferably an aliphatic hydrocarbon group having 1 to 3 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and even more preferably a methyl group.
n ^c1 to n ^c4 represent an integer of 0 to 5, preferably an integer of 0 to 2, more preferably 0 or 2, and even more preferably 2. When n ^c1 to n ^c4 are integers of 2 or more, the plurality of R ^c1s , R ^c2s , R ^c3s , or R ^c4s may be the same or different.
n ^c5 represents an integer of 0 to 5, preferably an integer of 1 to 3, more preferably 1 or 2, and even more preferably 1. When n ^c5 is an integer of 2 or more, the plurality of Z ^c1s and the plurality of n ^c4s may be the same or different.

The definitions of each group in the general formula (C1-2) are as described above.

The divalent fused polycyclic aromatic hydrocarbon group represented by Z ^c1 in the general formula (C1-1) is a group containing two hydrogen atoms from a fused polycyclic aromatic hydrocarbon group such as naphthalene, anthracene, pyrene, etc. Examples include divalent groups obtained by excluding. The fused polycyclic aromatic hydrocarbon group may be substituted with a substituent or not. Substituents of the fused polycyclic aromatic hydrocarbon group include carbon numbers such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, n-pentyl group, etc. 1 to 5 aliphatic hydrocarbon groups; examples include halogen atoms such as fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

Specific examples of the phosphate compound (C1) include 1,3-phenylene-bis(di-2,6-dimethylphenyl phosphate), 1,3-phenylene-bis(diphenyl phosphate), bisphenol A bis(diphenyl phosphate), 1,4-phenylene-bis(di-2,6-dimethylphenylphosphate), 4,4'-biphenylene-bis(di-2,6-dimethylphenylphosphate), bisphenol A-polyphenylphosphate, 4,4' -Biphenol-polycresyl phosphate, bisphenol A-polycresyl phosphate, 4,4'-biphenol-poly(2,6-xylenyl phosphate), bisphenol A-poly(2,6-xylenyl phosphate), etc. can be mentioned. As the phosphate compound (C1), 4,4'-biphenylene-bis(di-2,6-dimethylphenylphosphate) is preferred.
In addition, "poly" in the above specific example of the phosphate compound means a compound in which the number of repeating units consisting of a structure derived from a divalent phenol compound constituting the phosphate compound and a structure derived from phosphoric acid is 2 or more; Containing a compound may also mean that the average value of the repeating units exceeds 1. Here, the "repeating unit" refers to, for example, the structural unit within the square brackets in the general formula (C1-1).

((C2) Phosphine oxide compound)
One type of phosphine oxide compound may be used alone, or two or more types may be used in combination. A commercially available product can be used as the phosphine oxide compound.
The component (C2) preferably has two or more diphenylphosphine oxide groups in its molecule, more preferably two diphenylphosphine oxide groups in its molecule. Here, the diphenylphosphine oxide group is a group represented by the following formula.

(* indicates the bonding position.)

The phosphine oxide compound having two or more diphenylphosphine oxide groups in the molecule preferably has a linking group that connects the two or more diphenylphosphine oxide groups. Examples of the linking group include, but are not limited to, a phenylene group, a xylylene group, a biphenylene group, a naphthylene group, a methylene group, an ethylene group, and the like. From the viewpoint of component (C2) having a high melting point, the linking group preferably contains at least one selected from the group consisting of a phenylene group, a xylylene group, a biphenylene group, and a naphthylene group, and preferably contains a phenylene group. More preferred.

((C3) Phosphaphenanthrene compound)
One type of phosphaphenanthrene compound may be used alone, or two or more types may be used in combination. A commercially available product can be used as the phosphaphenanthrene compound.
As the component (C3), 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide, 9,10-dihydro-10-(2,5-dihydroxyphenyl)-9-oxa-10-phospho Examples include faphenanthrene 10-oxide.

((C4) Metal salt of phosphinic acid)
Component (C4) is preferably a metal salt of dialkylphosphinic acid. Here, examples of the "metal salt" include lithium salt, sodium salt, potassium salt, calcium salt, magnesium salt, aluminum salt, titanium salt, zinc salt, and the like. Among these, the metal salt is preferably an aluminum salt.
Furthermore, examples of the alkyl group possessed by the dialkylphosphinic acid include alkyl groups having 1 to 10 carbon atoms. The alkyl group is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and even more preferably an ethyl group.

((C5) Organic nitrogen-containing phosphorus compound)
As the component (C5), a phosphazene compound can be mentioned. A commercially available product can be used as the phosphazene compound.
The phosphazene compound may be a chain phosphazene compound or a cyclic phosphazene compound, but is preferably a cyclic phosphazene compound.

(Content of component (C) in varnish)
In the manufacturing method of the present embodiment, the content of component (C) in the varnish is 20 to 300 parts by mass, preferably 50 to 250 parts by mass, more preferably 75 parts by mass, per 100 parts by mass of component (A). ~225 parts by weight, more preferably 80 to 220 parts by weight, particularly preferably 85 to 215 parts by weight, may be 85 to 180 parts by weight, may be 85 to 150 parts by weight, and may be 85 to 150 parts by weight, It may be up to 120 parts by mass. In addition, the upper limit of the numerical range may be 200 parts by mass or less, 170 parts by mass or less, 130 parts by mass or less, or 110 parts by mass. or less. Here, the content of component (C) in the varnish also includes the amount of component (C) in the slurry.
If the amount used is within the above range, good low thermal expansion and heat resistance tend to be obtained when component (C) contains the above inorganic filler, and when component (C) contains the above flame retardant. tends to provide good flame retardancy.

In the manufacturing method of this embodiment, the varnish may further contain other components. Other components include, but are not particularly limited to, (D) thermoplastic resin, (E) surface treatment agent, (F) curing accelerator, flame retardant aid, antioxidant, adhesion improver, It is preferable to include one or more selected from the group consisting of heat stabilizers, antistatic agents, ultraviolet absorbers, pigments, colorants, and lubricants.

((D) Thermoplastic resin)
In the manufacturing method of this embodiment, although not particularly limited, it is also preferable to incorporate (D) a thermoplastic resin into the varnish.
The thermoplastic resin (D) includes a styrene thermoplastic elastomer, an olefin thermoplastic elastomer, a urethane thermoplastic elastomer, a polyester thermoplastic elastomer, a polyamide thermoplastic elastomer, an acrylic thermoplastic elastomer, and a silicone thermoplastic elastomer. Thermoplastic elastomers such as elastomers; polyphenylene ether resins, etc. may be mentioned. Here, the thermoplastic elastomer is composed of a hard segment component and a soft segment component, and generally, the hard segment component contributes to heat resistance and strength, and the soft segment component contributes to flexibility and toughness. are doing.
(D) Thermoplastic resins may be used alone or in combination of two or more.

The thermoplastic resin (D) is preferably a styrene thermoplastic elastomer from the viewpoint of dielectric loss tangent (Df). Here, in the present disclosure, the styrenic thermoplastic elastomer includes a hydrogenated styrenic thermoplastic elastomer. The styrene-based thermoplastic elastomer only needs to have a structural unit derived from a styrene-based compound, and from the viewpoints of dielectric loss tangent (Df), adhesion to conductors, heat resistance, and low thermal expansion, styrene-butadiene- selected from the group consisting of hydrogenated styrene block copolymers (SEBS or SBBS), hydrogenated styrene-isoprene-styrene block copolymers (SEPS), and styrene-maleic anhydride copolymers (SMA) One or more types are preferred, and one or more types selected from the group consisting of hydrogenated styrene-butadiene-styrene block copolymer (SEBS) and styrene-maleic anhydride copolymer (SMA) are more preferred.
Note that the styrenic thermoplastic elastomer (here, excluding the above-mentioned SMA) may be one modified with an acid anhydride such as maleic anhydride. and SEPS modified with an acid anhydride such as maleic anhydride. The acid value of the acid-modified styrenic thermoplastic elastomer (here, excluding the above-mentioned SMA) is not particularly limited, but is preferably 2 to 20 mg CH ₃ ONa/g, more preferably 5 to 15 mg CH ₃ ONa/g, More preferably 7 to 13 mg CH ₃ ONa/g.

In a styrenic thermoplastic elastomer (excluding the above-mentioned SMA), the content of structural units derived from styrene (hereinafter sometimes referred to as "styrene content"). ] is preferably 5 to 80% by mass, and preferably 10 to 75% by mass, from the viewpoint of dielectric loss tangent (Df), adhesion with conductors, heat resistance, and low thermal expansion, although it is not particularly limited. The amount is more preferably 15 to 60% by weight, even more preferably 20 to 45% by weight.
Furthermore, in the SMA, the molar ratio [styrene/maleic anhydride] of the structural unit derived from styrene and the structural unit derived from maleic anhydride is preferably 5 to 11, more preferably 6 to 10, and still more preferably 7 to 9. It is.
The weight average molecular weight (Mw) of the styrenic thermoplastic elastomer is not particularly limited, but is preferably from 12,000 to 1,000,000, more preferably from 30,000 to 500,000. It is preferably from 50,000 to 120,000, more preferably from 70,000 to 100,000.

(Content of component (D) in varnish)
In the manufacturing method of the present embodiment, the content of component (D) in the varnish is not particularly limited, but is preferably 1 to 100 parts by mass, and 5 to 70 parts by mass, based on 100 parts by mass of component (A). Parts by weight are more preferred, even more preferably 10 to 60 parts by weight, particularly preferably 25 to 55 parts by weight. Note that the content of the (D) component in the varnish includes the (D) component in the slurry when the (D) component is contained in a slurry containing the (B) component and the (C) component. It also includes the amount of ingredients. When the amount of component (D) used is more than the above lower limit, the dielectric loss tangent (Df) tends to decrease, and when it is less than the above upper limit, good heat resistance, moldability, workability and flame retardance are achieved. tends to be obtained.

((E) Surface treatment agent)
In the manufacturing method of this embodiment, the varnish may contain (E) a surface treatment agent. A coupling agent can be used as component (E). Examples of the coupling agent include a silane coupling agent and a titanate coupling agent. One type of coupling agent may be used alone, or two or more types may be used in combination.
When a surface treatment agent is used, the treatment method may be a so-called integral blend treatment method in which a coupling agent is added to the varnish. A method using . By employing these processing methods, the characteristics of the inorganic filler can be more effectively expressed.

(Content of component (E) in varnish)
In the manufacturing method of the present embodiment, the content of component (E) in the varnish is not particularly limited, but from the viewpoint of redispersibility of the slurry, the content of component (E) is 0 to 100 parts by mass of component (A). .1 to 10 parts by weight is preferable, 0.1 to 5 parts by weight is more preferable, and even more preferably 0.5 to 3 parts by weight. In addition, when the content of the (E) component in the varnish includes the (E) component in a slurry containing the (B) component and the (C) component, the content of the (E) component in the slurry It also includes the amount of ingredients.

((F) Curing accelerator)
In the manufacturing method of this embodiment, the varnish may contain (F) a curing accelerator.
Examples of the curing accelerator (F) include amine curing accelerators, imidazole curing accelerators, phosphorus curing accelerators, organic metal salts, acidic catalysts, and organic peroxides. In this embodiment, the imidazole-based curing accelerator is not classified as an amine-based curing accelerator. (F) The curing accelerator may be used alone or in combination of two or more. (F) The curing accelerator is preferably an amine-based curing accelerator, an imidazole-based curing accelerator, or a phosphorus-based curing accelerator, and more preferably an amine-based curing accelerator or an imidazole-based curing accelerator.
Examples of the amine curing accelerator include amine compounds having primary to tertiary amino groups such as triethylamine, 4-aminopyridine, tributylamine, and dicyandiamide; quaternary ammonium compounds, and the like.
As the imidazole curing accelerator, imidazole compounds such as methylimidazole, phenylimidazole, 2-undecylimidazole, isocyanate mask imidazole (for example, an addition reaction product of hexamethylene diisocyanate resin and 2-ethyl-4-methylimidazole), etc. can be mentioned.
Examples of the phosphorus-based curing accelerator include tertiary phosphines such as triphenylphosphine; and quaternary phosphonium compounds such as tri-n-butylphosphine addition reaction product of p-benzoquinone.

(Content of (F) component in varnish)
In the manufacturing method of the present embodiment, the content of component (F) in the varnish is not particularly limited, but from the viewpoint of storage stability of the varnish and physical properties of the laminate, the content of component (A) is 100 parts by mass. The amount is preferably 0.1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, and even more preferably 0.5 to 3 parts by weight. Note that the content of the (F) component in the varnish includes (D) in the slurry when the (F) component is contained in a slurry containing the (B) component and the (C) component. It also includes the amount of ingredients.

(organic solvent)
The varnish obtained by the manufacturing method of this embodiment contains an organic solvent.
The organic solvent is not particularly limited, but includes alcoholic solvents such as ethanol, propanol, butanol, methyl cellosolve, butyl cellosolve, and propylene glycol monomethyl ether; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. ; Ether solvents such as tetrahydrofuran; Aromatic solvents such as toluene, xylene, and mesitylene; Nitrogen-containing solvents such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone; Sulfur-containing solvents such as dimethyl sulfoxide; γ-butyrolactone, etc. Examples include ester solvents. From the viewpoint of solubility, ketone solvents and aromatic solvents are preferred, ketone solvents are more preferred, and methyl isobutyl ketone is even more preferred. One type of organic solvent may be used alone, or two or more types may be used in combination.

In this embodiment, the solid content concentration of the varnish is preferably 40 to 90% by mass, more preferably 50 to 80% by mass, and even more preferably 55 to 70% by mass. When the solid content concentration of the varnish is within the above range, the varnish will be easy to handle, will have good impregnability into the base material and the appearance of the manufactured prepreg, and will have good coating properties when made into a resin film. Become.

In this embodiment, the varnish can be manufactured by mixing the components with a slurry containing the components (B) and (C). At this time, each component may be dissolved or dispersed in the organic solvent while stirring. Conditions such as mixing order, temperature, time, etc. are not particularly limited and can be set arbitrarily.
The varnish obtained by the manufacturing method of this embodiment can exhibit a high dielectric constant (Dk) and a low dielectric loss tangent (Df), so it is suitable for use in antenna modules, especially small-sized ones compatible with the 5th generation mobile communication system (5G). It is useful for use as an integrated antenna module.

[Prepreg manufacturing method]
One of the present embodiments is a prepreg manufacturing method that includes impregnating or coating a sheet-like fiber base material with the varnish obtained by the manufacturing method of the present embodiment and then drying the varnish.
Specifically, a prepreg is obtained by impregnating or coating a sheet-like fiber base material with the varnish obtained by the manufacturing method of the present embodiment, drying, and semi-curing (B-staged) as necessary. be able to. More specifically, the drying method includes, for example, producing a prepreg by heating and drying for 1 to 30 minutes in a drying oven at a temperature of 80 to 200 ° C. to semi-cure (B stage). I can do it. Here, in the present disclosure, B-staging refers to making a B-stage state defined in JIS K6900 (1994).
The prepreg after drying preferably has a varnish-derived solid content concentration of 30 to 90% by mass. By setting the concentration of solid content derived from the varnish within the above range, better moldability tends to be obtained when it is made into a laminate.

As the sheet-like fiber base material, known materials used in various electrically insulating material laminates can be used. Examples of the material for the sheet-like fiber base material include inorganic fibers such as E glass, D glass, S glass, and Q glass; organic fibers such as polyimide, polyester, and tetrafluoroethylene; and mixtures thereof. These sheet-like fiber substrates have shapes such as woven fabrics, nonwoven fabrics, raw binders, chopped strand mats, or surfacing mats.
The thickness of the prepreg is not particularly limited, and may be 10 to 170 μm, 20 to 150 μm, or 30 to 120 μm.

The prepreg obtained by the manufacturing method of this embodiment can exhibit a high dielectric constant (Dk) and a low dielectric loss tangent (Df), so it is useful for antenna modules, especially for miniaturized antenna modules compatible with 5G. .

[Method for manufacturing resin film]
One of the embodiments is a method for producing a resin film, which includes applying a varnish obtained by the production method of the embodiment to a support and then drying the varnish.
Specifically, a resin film can be produced by applying a varnish to a support, drying it, and semi-curing (B-staging) if necessary.
Examples of the support include a plastic film, metal foil, and release paper.
The drying temperature and drying time may be determined as appropriate depending on the amount of organic solvent used and the boiling point of the organic solvent used, but the resin film can be dried by heating at 50 to 200°C for about 1 to 10 minutes. It can be formed suitably.
The resin film obtained by the manufacturing method of this embodiment can exhibit a high dielectric constant (Dk) and a low dielectric loss tangent (Df), so it is useful for antenna modules, especially for miniaturized antenna modules compatible with 5G. be.

[Method for manufacturing laminate]
One of the present embodiments is to arrange metal foil on one or both sides of a prepreg obtained by stacking two or more sheets of prepreg obtained by the manufacturing method of this embodiment, or to combine the prepreg and other prepregs. This is a method for manufacturing a laminate, which includes arranging metal foil on one or both sides of prepreg obtained by stacking two or more sheets, and then heat-pressing forming. The prepreg in the laminate obtained by this manufacturing method is C-staged. In the present disclosure, C-staging refers to bringing the material into a C-stage state as defined in JIS K6900 (1994). Note that a laminate having metal foil is sometimes referred to as a metal-clad laminate.
The metal of the metal foil is not particularly limited, but from the viewpoint of conductivity, copper, gold, silver, nickel, platinum, molybdenum, ruthenium, aluminum, tungsten, iron, titanium, chromium, or one of these metal elements can be used. It may be an alloy containing the above, copper and aluminum are preferred, and copper is more preferred.
The conditions for hot-press molding are not particularly limited, but can be carried out, for example, at a temperature of 100 to 300°C, a pressure of 0.2 to 10 MPa, and a time of 0.1 to 5 hours. Further, for the heating and pressure forming, a method of maintaining a vacuum state for 0.5 to 5 hours using a vacuum press or the like can be adopted.

Considering that the laminate is used for an antenna module, the method for manufacturing a laminate of this embodiment makes it possible to form conductor patterns such as a power feeding conductor pattern, a grounding conductor pattern, and a shorting conductor on the laminate. preferable. The short-circuiting conductor is a conductor that short-circuits the power feeding conductor pattern and the grounding conductor pattern, and is provided at a via hole portion to be described later.
The conductor pattern is preferably formed of a metal whose main component is copper, aluminum, gold, silver, or an alloy thereof.

In the method for manufacturing a laminate of this embodiment, it is preferable to form via holes in the laminate. The via hole makes it possible to form the shorting conductor, thereby making it possible to conduct the power feeding conductor pattern and the grounding conductor pattern.
There are no particular limitations on the method for forming via holes, and methods such as laser, plasma, or a combination thereof can be used. As the laser, a carbon dioxide laser, a YAG laser, a UV laser, an excimer laser, etc. can be used.
Further, after forming the via hole, desmear treatment may be performed using an oxidizing agent. The oxidizing agent is preferably a permanganate such as potassium permanganate or sodium permanganate; dichromate; ozone; hydrogen peroxide-sulfuric acid; nitric acid, and more preferably a permanganate. , an aqueous sodium hydroxide solution of permanganate, a so-called alkaline aqueous permanganic acid solution is more preferable.

In the method for manufacturing a laminate of this embodiment, it is preferable that a shorting conductor is formed in the via hole after the via hole is formed. The conductor used here is preferably formed of the same metal as the metal forming the conductor pattern.

The laminate obtained by the manufacturing method of this embodiment has a high dielectric constant (Dk) and a low dielectric loss tangent (Df), so it is suitable for antenna modules, especially for miniaturized antenna modules compatible with 5G. Useful.

(Printed wiring board)
Using one or more selected from the group consisting of a prepreg obtained by the production method of this embodiment, a resin film obtained by the production method of this embodiment, and a laminate obtained by the production method of this embodiment, known Depending on the method, a printed wiring board can be manufactured by performing circuit forming processing such as drilling, metal plating, and etching of metal foil. Moreover, a multilayer printed wiring board can be manufactured by further performing a multilayer adhesive process as required.

(antenna device)
According to the present disclosure, an antenna device can be manufactured using a laminate obtained by the manufacturing method of this embodiment. The antenna device may be one in which one of the above laminates is installed, or may be one in which a plurality of the above laminates are installed. Although there is no particular restriction on how to install the plurality of antenna elements, it is preferable, for example, to arrange them in a two-dimensional array. The configuration of the antenna device is not particularly limited, and for example, Japanese Patent No. 6777273 can be referred to.

(antenna module)
An antenna module can be manufactured using a power feeding circuit and the antenna device. The power supply circuit is not particularly limited, but an RFIC (Radio Frequency Integrated Circuit) or the like can be used. The RFIC includes a switch, a power amplifier, a low-noise amplifier, an attenuator, a phase shifter, a signal combiner/brancher, a mixer, an amplifier circuit, and the like.
The high frequency signal supplied from the RFIC is transmitted to the power feeding point of the power feeding conductor via a shorting conductor formed in a via of the antenna module laminate.
The configuration of the antenna module is not particularly limited, and for example, Japanese Patent No. 6777273 can be referred to.

(Communication device)
Furthermore, a communication device can be manufactured using the baseband signal processing circuit and the antenna module.
The communication device up-converts the signal transmitted from the baseband signal processing circuit to the antenna module into a high-frequency signal and radiates it from the antenna device, and down-converts the high-frequency signal received by the antenna device to transmit the high-frequency signal to the baseband signal processing circuit. The signal can be processed at

Although the preferred embodiments have been described above, these are examples for explaining the present disclosure, and the scope of the present disclosure is not intended to be limited only to these embodiments. The present disclosure also includes various aspects different from the embodiments described above without departing from the gist thereof.

Hereinafter, this embodiment will be specifically described with reference to Examples. However, this embodiment is not limited to the following examples.

In addition, in each example, the weight average molecular weight (Mw) was measured by the following method.
(Method for measuring weight average molecular weight (Mw))
Calculation was performed using gel permeation chromatography (GPC) using a calibration curve using standard polystyrene. The calibration curve is based on standard polystyrene: TSK standard POLYSTYRENE (Type; A-2500, A-5000, F-1, F-2, F-4, F-10, F-20, F-40) [manufactured by Tosoh Corporation, Product name] was approximated by a cubic equation. GPC measurement conditions are shown below.
Device:
Pump: L-6200 type [manufactured by Hitachi High-Technologies Corporation]
Detector: L-3300 type RI [manufactured by Hitachi High-Technologies Corporation]
Column oven: L-655A-52 [manufactured by Hitachi High-Technologies Corporation]
Column: Guard column; TSK Guardcolumn HHR-L+ column; TSKgel G4000HHR+TSKgel G2000HHR (all manufactured by Tosoh Corporation, product names)
Column size: 6.0 x 40 mm (guard column), 7.8 x 300 mm (column)
Eluent: Tetrahydrofuran Sample concentration: 30mg/5mL
Injection volume: 20μL
Flow rate: 1.00mL/min Measurement temperature: 40℃

Furthermore, the average particle diameter of component (B) and component (C) used in each example was measured by the following method.
(Method for measuring average particle diameter)
The particle size distribution was measured using a particle size distribution measuring device "Microtrac MT3300EXII" (manufactured by Microtrac Bell Co., Ltd.), and the average particle size (d50) was determined. Note that water (containing 0.1% by mass of sodium hexametaphosphate) was used as the measurement solvent, the measurement mode was set to transmission, and the measurement time was 30 seconds.

[Production Example 1: Production of modified maleimide compound]
100 parts by mass of 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane was placed in a 5 L reaction vessel that can be heated and cooled and equipped with a thermometer, a stirring device, and a moisture meter with a reflux condenser. 5.6 parts by mass of a siloxane compound having amino groups at both ends (functional group equivalent: 750 g/mol), 7.9 parts by mass of 3,3'-diethyl-4,4'-diaminodiphenylmethane, and 171 parts by mass of propylene glycol monomethyl ether. parts by mass were added, and the mixture was reacted for 2 hours under reflux. This was concentrated at reflux temperature for 3 hours to produce a modified maleimide compound solution with a solid content concentration of 65% by mass. The weight average molecular weight (Mw) of the obtained modified maleimide compound was 2,700.

[Example 1]
(Preparation of slurry)
After adding component (B-1) to the mixed solution of component (C-1) and methyl isobutyl ketone in the usage amount listed in the upper row of Table 1, the slurry was prepared by stirring at 25°C for 6 hours with a motor stirrer. Obtained.
(Preparation of varnish)
The slurry obtained above was mixed with each component and the amount used as shown in the lower part of Table 1 to prepare a varnish having the composition ratio shown in the lower part of Table 1.
(Preparation of prepreg)
A prepreg was obtained by impregnating a glass cloth (thickness: 0.08 mm) of IPC standard #3313 with the resin varnish obtained above and drying it at 150° C. for 5 minutes.
(Production of double-sided copper-clad laminate)
A low profile copper foil (BF-ANP18, Rz of M side: 1.5 μm, manufactured by CIRCUIT FOIL) with a thickness of 18 μm was placed on the top and bottom of the prepreg obtained above, respectively, so that the M side (matte side) was in contact with the prepreg. A double-sided copper-clad laminate (thickness: 0.10 mm) was produced by heat-pressing molding at a temperature of 230° C., a pressure of 3.0 MPa, and a time of 90 minutes.
Using the obtained slurry, varnish, and double-sided copper-clad laminate, various evaluations were performed according to the following methods. The results are shown in Table 1.

[Slurry evaluation]
(1. Possibility of preparing slurry)
When preparing the slurry, it was evaluated visually according to the following evaluation criteria.
A: It was possible to prepare a slurry.
B: It was difficult to prepare a slurry because it did not become liquid.
C: The slurry could not be prepared due to gelation.
(2. Redispersibility of slurry)
The slurry was introduced into a polybottle, allowed to stand for one day, and then stirred by shaking the polybottle by hand. The condition inside the polybottle was visually observed and evaluated according to the following evaluation criteria.
A: Precipitation was observed in the slurry before stirring, but the components in the slurry were redispersed by simply shaking the polyethylene bottle by hand.
B: Precipitation was observed in the slurry before stirring, but by shaking the polybottle by hand, the components in the slurry were redispersed.
C: Precipitation was observed in the slurry before stirring, but the components in the slurry were redispersed by shaking the polybottle vigorously by hand.
D: Before stirring, the slurry was separated into a liquid phase and a solid phase, but by shaking the polyethylene bottle vigorously by hand, the components in the slurry were redispersed.
E: Before stirring, the slurry was separated into a liquid phase and a solid phase, and although the polybottle was shaken violently by hand, it was impossible to redisperse the components in the slurry.

[Evaluation of varnish]
(3. Presence or absence of aggregates in varnish)
A mixture obtained by adding 0.1 mL of the varnish obtained in each example to 3 mL of methyl isobutyl ketone was used as a varnish evaluation sample. Using 1 to 2 mL of the evaluation sample prepared above, the particle size distribution was measured using a particle size distribution measuring device "Microtrac MT3300EXII" (manufactured by Microtrac Bell Co., Ltd.), and evaluated according to the following evaluation criteria. The measurement was carried out using methyl isobutyl ketone as the measurement solvent, the measurement mode was set to transmission, and the measurement time was 30 seconds. The measurement was performed twice, and the average value of the two measurements was adopted as the particle size distribution of the substance contained in the evaluation sample.
A: There were no aggregates with a size of 100 μm or more in the varnish.
C: Aggregates with a size of 100 μm or more were present in the varnish.

[Evaluation of cured product]
(4. Appearance)
An evaluation board was prepared by removing the copper foil by immersing the double-sided copper-clad laminate obtained in each example in a 10% by mass solution of ammonium persulfate, which is a copper etching solution, and the surface of the evaluation board was visually observed. Evaluation was made according to the evaluation criteria.
A: No aggregates were observed on the surface.
C: Aggregates were observed on the surface.

[Example 2]
(Preparation of slurry)
Component (B-1) was added to the mixed solution of component (C-1) and methyl isobutyl ketone in the amount shown in the upper part of Table 1, and the mixture was stirred for 3 hours at 25°C using a motor stirrer. A slurry was obtained by adding the -2) ingredients and then stirring with a motor stirrer at 25°C for 3 hours.
(Preparation of varnish, production of prepreg, production of copper-clad laminates)
A varnish was prepared, a prepreg was produced, and a copper-clad laminate was produced by performing the same operations as in Example 1 except that the above slurry was used.
Using the obtained slurry, varnish, and double-sided copper-clad laminate, various evaluations were performed according to the methods described above. The results are shown in Table 1.

[Examples 3-4]
(Preparation of slurry)
Add component (A-2) or component (D-2) to the mixed solution of component (C-1) and methyl isobutyl ketone in the amounts listed in the upper row of Table 1, and then use a motor stirrer to heat the mixture at 25°C for 1 hour. Component (A-2) or (D-2) was dissolved by stirring. Thereafter, component (B-1) is further added and stirred at 25°C for 3 hours using a motor stirrer, and finally component (C-2) is added and further stirred at 25°C for 3 hours using a motor stirrer. A slurry was obtained by
(Preparation of varnish, production of prepreg, production of copper-clad laminates)
A varnish was prepared, a prepreg was produced, and a copper-clad laminate was produced by performing the same operations as in Example 1 except that the above slurry was used.
Using the obtained slurry, varnish, and double-sided copper-clad laminate, various evaluations were performed according to the methods described above. The results are shown in Table 1.

[Examples 5-6]
(Preparation of slurry)
Add component (A-2) or component (D-2) to the mixed solution of component (C-1) and methyl isobutyl ketone in the amounts listed in the upper row of Table 1, and then use a motor stirrer to heat the mixture at 25°C for 1 hour. Component (A-2) or (D-2) was dissolved by stirring. Thereafter, component (B-1) was further added and stirred at 25° C. for 3 hours using a motor stirrer, and then component (C-2) was added and stirred for 3 hours at 25° C. using a motor stirrer. Thereafter, component (E-1) was further added and the mixture was stirred at 25° C. for 1 hour using a motor stirrer to obtain a slurry.
(Preparation of varnish, production of prepreg, production of copper-clad laminates)
A varnish was prepared, a prepreg was produced, and a copper-clad laminate was produced by performing the same operations as in Example 1 except that the above slurry was used.
Using the obtained slurry, varnish, and double-sided copper-clad laminate, various evaluations were performed according to the methods described above. The results are shown in Table 1.

[Comparative Examples 1 to 5]
(Preparation of slurry)
One or more components selected from the group consisting of components (B-1), (B-2) and (B-3) are added to methyl isobutyl ketone in the usage amounts listed in the upper row of Table 1, and then mixed with a motor stirrer. A slurry was obtained by stirring at 25°C for 6 hours.
(Preparation of varnish, production of prepreg, production of copper-clad laminates)
A varnish was prepared, a prepreg was produced, and a copper-clad laminate was produced by performing the same operations as in Example 1 except that the above slurry was used.
Using the obtained slurry, varnish, and double-sided copper-clad laminate, various evaluations were performed according to the methods described above. The results are shown in Table 1.
In Comparative Examples 4 and 5, varnishes and copper-clad laminates were produced using the slurry after the slurry redispersibility evaluation test, and each evaluation was also performed on these according to the above-mentioned method. The results are also shown in Table 1.

Each component listed in Table 1 will be explained below.
[(A) Thermosetting resin]
・(A-1): Modified maleimide compound obtained in Production Example 1 ・(A-2): Naphthalene skeleton-containing epoxy resin "NC-7000L" (manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent: 230 g/eq)

[(B) Inorganic filler]
・(B-1): Calcium titanate, average particle size (d50); 2.0 μm
・(B-2): Calcium titanate, average particle size (d50); 0.3 μm
・(B-3): Calcium titanate, average particle size (d50); 0.5 μm

[(C) Particles having an average particle diameter smaller than the average particle diameter of the component (B)]
・(C-1): Spherical fused silica (surface treated product with phenylaminosilane coupling agent), average particle size: 0.5 μm, slurry with solid content concentration of 70% by mass (methyl isobutyl ketone dispersion), inorganic filler. (C-2): 4,4'-bisphenol-bis(di-2,6-dimethylphenylphosphate), average particle size: 1.5 μm, flame retardant

[(D) Thermoplastic resin]
・(D-1): Maleic anhydride-modified styrenic thermoplastic elastomer (maleic anhydride-modified SEBS), acid value 10 mg CH ₃ ONa/g, styrene content 30% by mass
・(D-2): Copolymer of styrene and maleic anhydride, styrene/maleic anhydride (mole ratio) = 8

[(E) Surface treatment agent]
- (E-1): terminal long chain alkyl fatty acid modified titanate "KR-TTS" (manufactured by Ajinomoto Fine Techno Co., Ltd.), a surface treatment agent that does not have a tertiary amino group.

[(F) Curing accelerator]
・(F-1): Isocyanate mask imidazole "G8009-L" (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
・(F-2): Dicyandiamide

Table 1 shows that according to the methods of Examples 1 to 6, it is easy to prepare a slurry containing component (B), and the redispersibility of the slurry is also good or excellent. The generation of aggregates in the varnish was suppressed, and therefore, no aggregates were observed in the cured product.
On the other hand, in the methods of Comparative Examples 1 to 3, it was difficult to prepare the slurry containing component (B) due to gelation. In addition, in the methods of Comparative Examples 1 to 3, aggregates were present in the varnish prepared using the gelled product containing component (B), and aggregates were also observed on the surface of the cured product of the varnish. .
Further, in the methods of Comparative Examples 4 and 5, although the slurry preparation itself was easy, the redispersibility of the slurry was poor. Therefore, aggregates were present in the varnish prepared using the slurry after the redispersibility evaluation test, and aggregates were also observed on the surface of the cured product of the varnish.

Claims (13)

(A) 100 parts by mass of a thermosetting resin, (B) 50 to 400 parts by mass of at least one inorganic filler selected from the group consisting of titanium-based inorganic fillers and zircon-based inorganic fillers, (C) the above ( B) A method for producing a varnish containing 20 to 300 parts by mass of particles having an average particle diameter smaller than the average particle diameter of component and an organic solvent,
Prepare a slurry by dispersing the component (B) together with the component (C) in a liquid, and then mix it with 80 parts by mass or more of 100 parts by mass of the thermosetting resin (A) to form a varnish. ,
A method of manufacturing a varnish, including: The method for producing a varnish according to claim 1, wherein the average particle diameter of the component (C) is smaller than the average particle diameter of the component (B) by 0.3 μm or more. The method for producing a varnish according to claim 1, wherein the average particle diameter of the component (B) is 0.1 to 4.0 μm. When preparing a slurry by dispersing the component (B) together with the component (C) in a liquid, the method includes adding and mixing the component (B) to the slurry in which the component (C) is dispersed. A method for producing a varnish according to claim 1. When preparing a slurry by dispersing the (B) component together with the (C) component in a liquid, (A) thermosetting is added to 100 parts by mass of the (B) component and (C) component in total. 2. The method according to claim 1, further comprising dispersing 1 to 10 parts by mass of at least one selected from the group consisting of a thermoplastic resin and a thermoplastic resin (D) into a liquid together with the component (B) and the component (C). varnish manufacturing method. The method for producing a varnish according to claim 1, wherein the titanium-based inorganic filler is at least one selected from the group consisting of titanium dioxide and metal titanate. The method for producing a varnish according to claim 6, wherein the metal titanate is at least one selected from the group consisting of an alkali metal titanate, an alkaline earth metal titanate, and a lead titanate. The method for producing a varnish according to claim 1, wherein the zircon-based inorganic filler is an alkali metal zirconate salt. The method for producing a varnish according to claim 1, wherein the component (C) contains at least one selected from the group consisting of an inorganic filler and a flame retardant. The method for producing a varnish according to claim 1, wherein the liquid contains a ketone solvent. A method for producing a prepreg, comprising impregnating or coating a sheet-like fiber base material with the varnish obtained by the production method according to any one of claims 1 to 10, and then drying the varnish. A method for producing a resin film, comprising applying a varnish obtained by the production method according to any one of claims 1 to 10 to a support and then drying the varnish. A metal foil is arranged on one or both sides of a prepreg obtained by stacking two or more prepregs obtained by the manufacturing method according to claim 11, or a prepreg obtained by stacking two or more prepregs in total with the prepreg obtained by the manufacturing method according to claim 11. A method for manufacturing a laminate, the method comprising placing a metal foil on one or both sides of a prepreg, followed by heating and pressure forming.