JP7600582B2 - Resin composition - Google Patents

Description

The present invention relates to a resin composition. It also relates to a cured product, a resin sheet, a reflective sheet, and a printed wiring board obtained using the resin composition.

In printed wiring boards, there is an increasing use of low-power light-emitting diodes (LEDs) that are directly mounted on the board, such as for backlighting liquid crystal displays in mobile terminals, computers, televisions, etc., and as light sources for lighting fixtures.

A reflective sheet is formed on the outermost layer of such a printed wiring board to reflect light and increase the efficiency of extracting light emitted from the light source.

Epoxy resin compositions used in reflective sheeting applications mainly use acid anhydrides as epoxy curing agents. However, when acid anhydrides are used, problems with adhesion to the underlying wiring may occur due to ester bond cleavage during curing, especially after HAST (High Speed Accelerated Life Test). On the other hand, such problems can be solved by using phenolic resin as the epoxy curing agent, but the use of phenolic resin poses problems with yellowing resistance.

On the other hand, resin compositions using fluorine-based resins for use in reflective sheets have been known (Patent Document 1).

Patent No. 4914221

The objective of the present invention is to provide a resin composition that produces a cured product that has excellent adhesion to the underlying wiring and excellent reflectance.

As a result of intensive research to solve the above problems, the inventors have unexpectedly discovered that when a composition contains (A) a curing agent, (B) an epoxy resin, and (C) a white inorganic pigment, and when (A) the curing agent contains a specific bisphenol-based curing agent, it is possible to obtain a cured product that has excellent adhesion to the underlying wiring and excellent reflectance, and have completed the present invention.

That is, the present invention includes the following.
[1] A resin composition comprising (A) a curing agent, (B) an epoxy resin, and (C) a white inorganic pigment,
A resin composition, wherein the component (A) contains a curing agent selected from a bisphenol compound having a fluorine atom, a bisphenol compound having an alicyclic structure, and a bisphenol compound having a fluorene skeleton.
[2] A resin composition comprising (A) a curing agent, (B) an epoxy resin, and (C) a white inorganic pigment,
The component (A) is represented by the following formula (I):

[wherein R ¹ is the same or different and represents an alkyl group or an alkyl group substituted with a fluorine atom, or two R ¹ are bonded together to form a carbon ring which may be substituted with a group selected from an alkyl group and a fluorine atom, R ² is the same or different and represents an alkyl group or a fluorine atom, and a is the same or different and represents an integer of 0 to 4.]
[3] The resin composition according to the above [1] or [2], wherein the component (A) contains a bisphenol compound having a fluorine atom.
[4] The resin composition according to the above [3], wherein the component (A) contains 2,2-bis(4-hydroxyphenyl)hexafluoropropane (bisphenol AF).
[5] The resin composition according to any one of the above [1] to [4], wherein the content of the component (A) is 1% by mass to 20% by mass, based on 100% by mass of the non-volatile components in the resin composition.
[6] The resin composition according to any one of the above [1] to [5], wherein the content of the component (C) is 10% by mass to 60% by mass, based on 100% by mass of the non-volatile components in the resin composition.
[7] The resin composition according to any one of the above [1] to [6], wherein the component (C) is selected from aluminum oxide, titanium oxide, zirconium oxide, magnesium oxide, barium titanate, zinc oxide, cerium oxide, and calcium carbonate.
[8] The resin composition according to any one of [1] to [7] above, wherein the content of the component (B) is 10% by mass to 35% by mass, based on 100% by mass of the non-volatile components in the resin composition.
[9] The resin composition according to any one of the above [1] to [8], wherein the mass ratio of the component (A) to the component (B) (mass of the component (A)/mass of the component (B)) is 0.1 to 1.0.
[10] The resin composition according to any one of the above [1] to [9], wherein the mass ratio of the component (C) to the component (B) (mass of the component (C)/mass of the component (B)) is 3.0 or less.
[11] The resin composition according to any one of the above [1] to [10], further comprising (D) silica.
[12] The resin composition according to the above [11], wherein the total content of the (C) component and the (D) component is 30% by mass to 80% by mass, where the total amount of non-volatile components in the resin composition is 100% by mass.
[13] The resin composition according to the above [11] or [12], wherein the mass ratio of the component (D) to the component (C) (mass of the component (D) / mass of the component (C)) is 5.0 or less.
[14] The resin composition according to any one of the above [1] to [13], wherein the adhesive strength of a cured product of the resin composition to a copper substrate at 23°C is 0.3 kgf/cm or more.
[15] The resin composition according to any one of the above [1] to [14], wherein a cured product of the resin composition has a reflectance of 90% or more for light with a wavelength of 460 nm.
[16] The resin composition according to any one of the above [1] to [15], which is for light reflection.
[17] A cured product of the resin composition according to any one of [1] to [16] above.
[18] A resin sheet comprising a support and a resin composition layer formed from the resin composition according to any one of [1] to [16] above, provided on the support.
[19] A reflecting sheet comprising a cured product of the resin composition according to any one of [1] to [16] above.
[20] A printed wiring board comprising the reflective sheet according to [19] above as an interlayer insulating layer or a solder resist layer.

The resin composition of the present invention can produce a cured product that has excellent adhesion to the underlying wiring and excellent reflectance.

FIG. 1 is a schematic cross-sectional view showing an example of a printed wiring board.

The present invention will be described in detail below with reference to preferred embodiments. However, the present invention is not limited to the following embodiments and examples, and may be modified as desired without departing from the scope of the claims of the present invention and their equivalents.

[Resin composition]
In a first embodiment, the resin composition of the present invention comprises (A) a curing agent, (B) an epoxy resin, and (C) a white inorganic pigment, and the (A) curing agent comprises a curing agent selected from a bisphenol compound having a fluorine atom, a bisphenol compound having an alicyclic structure, and a bisphenol compound having a fluorene skeleton.

In a second embodiment, the resin composition of the present invention comprises (A) a curing agent, (B) an epoxy resin, and (C) a white inorganic pigment, and the (A) curing agent is represented by the following formula (I):

[wherein R ¹ is the same or different and represents an alkyl group or an alkyl group substituted with a fluorine atom, or two R ¹ are bonded together to form a carbon ring which may be substituted with a group selected from an alkyl group and a fluorine atom, R ² is the same or different and represents an alkyl group or a fluorine atom, and a is the same or different and represents an integer of 0 to 4.]

By using such a resin composition, it is possible to obtain a cured product that has excellent adhesion to the underlying wiring and excellent reflectance.

The resin composition may contain optional components in addition to (A) the curing agent, (B) the epoxy resin, and (C) the white inorganic pigment. Examples of optional components include (D) silica, (E) the curing accelerator, (F) the thermoplastic resin, (G) the antioxidant, (H) the ultraviolet absorber, (I) other additives, and (J) the organic solvent. Each component contained in the resin composition will be described in detail below.

<(A) Curing Agent>
The resin composition of the present invention contains a curing agent (A). The curing agent (A) has a function of reacting with the epoxy resin (B) to cure the resin composition. The curing agent (A) may be used alone or in combination of two or more kinds.

In the first embodiment, the (A) curing agent includes a curing agent selected from a bisphenol compound having a fluorine atom, a bisphenol compound having an alicyclic structure, and a bisphenol compound having a fluorene skeleton (hereinafter sometimes referred to as "specific bisphenol-based curing agent A"), and preferably includes a bisphenol compound having a fluorine atom. A bisphenol compound is a compound having two phenols. Examples of the alicyclic structure in the "bisphenol compound having an alicyclic structure" include saturated carbon ring structures having 3 to 15 carbon atoms, such as monocycloalkane rings such as a cyclopentane ring, a cyclohexane ring, and a cyclododecane ring; bicycloalkane rings such as a norbornane ring, a decalin ring, and a hydrindane ring; and tricycloalkane rings such as a tetrahydrodicyclopentadiene ring and an adamantane ring.

In the second embodiment, the curing agent (A) is represented by the following formula (I):

[wherein R ¹ is the same or different and represents an alkyl group or an alkyl group substituted with a fluorine atom, or two R ¹ are bonded together to form a carbon ring which may be substituted with a group selected from an alkyl group and a fluorine atom, R ² is the same or different and represents an alkyl group or a fluorine atom, and a is the same or different and represents an integer of 0 to 4.] (hereinafter, may be referred to as "specific bisphenol-based curing agent B").

The alkyl group is a linear, branched, and/or cyclic monovalent saturated hydrocarbon group, preferably an alkyl group having 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms, such as a methyl group, an ethyl group, or a propyl group.

The carbocyclic ring formed by two R ^1s is a non-aromatic carbocyclic ring, or a partially saturated fused carbocyclic ring in which an aromatic carbocyclic ring is fused to a non-aromatic carbocyclic ring, and is preferably a carbocyclic ring having 3 to 15 carbon atoms. Examples of the carbocyclic ring include monocycloalkane rings such as a cyclopentane ring, a cyclohexane ring, and a cyclododecane ring; bicycloalkane rings such as a norbornane ring, a decalin ring, and a hydrindane ring; tricycloalkane rings such as a tetrahydrodicyclopentadiene ring and an adamantane ring; bicyclic partially saturated fused carbocyclic rings such as an indane ring, an indene ring, a tetralin ring, a 1,2-dihydronaphthalene ring, and a 1,4-dihydronaphthalene ring; and tricyclic partially saturated fused carbocyclic rings such as a fluorene ring and a 9,10-dihydroanthracene ring.

In formula (I), formula (A):

[In the formula, * indicates a binding site, and ^R1 is the same as above.]
The structural portion represented by the formulae (Aa) to (Ad):

[wherein R ^1′ and R ³ are the same or different and each represents an alkyl group or an alkyl group substituted with a fluorine atom, m represents an integer of 0 to 10, n represents 0 or 1, b represents an integer of 0 to 4, and * represents a bonding site.]

The phenolic hydroxyl group equivalent of the specific bisphenol-based curing agent A or the specific bisphenol-based curing agent B is preferably 50 g/eq. to 3000 g/eq., more preferably 100 g/eq. to 1000 g/eq., even more preferably 100 g/eq. to 500 g/eq., and particularly preferably 100 g/eq. to 300 g/eq. The phenolic hydroxyl group equivalent is the mass of the curing agent per equivalent of phenolic hydroxyl group.

Specific examples of the specific bisphenol-based curing agent A or the specific bisphenol-based curing agent B include, for example, 2,2-bis(4-hydroxyphenyl)hexafluoropropane (bisphenol AF), 1,1-bis(4-hydroxyphenyl)cyclohexane (bisphenol Z), 1,1-bis(4-hydroxyphenyl)cyclododecane, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, and 2,2-bis(3-fluoro-4-hydroxyphenyl)propane, among which bisphenol AF is preferred.

Specific examples of commercially available specific bisphenol-based hardener A or specific bisphenol-based hardener B include "BIS-AF" and "BIS-Z" manufactured by Central Glass Co., Ltd., and "BisOFP-A", "BisOC-FL", and "BisP-CDE" manufactured by Honshu Chemical Industry Co., Ltd.

The (A) curing agent may further contain other curing agents. The other curing agents are not particularly limited, but examples thereof include other phenol-based curing agents, carbodiimide-based curing agents, amine-based curing agents, benzoxazine-based curing agents, cyanate ester-based curing agents, and thiol-based curing agents.

Other phenol-based hardeners include, for example, biphenyl-type phenol-based hardeners, naphthalene-type phenol-based hardeners, phenol novolac-type phenol-based hardeners, naphthylene ether-type phenol-based hardeners, triazine skeleton-containing phenol-based hardeners, polyphenylene ether-type phenol-based hardeners, phenol aralkyl-type phenol-based hardeners, cresol novolac-type phenol-based hardeners, bisphenol-type phenol-based hardeners, etc.

Carbodiimide-based curing agents are curing agents that have two or more carbodiimide structures in one molecule, and examples of such curing agents include aliphatic biscarbodiimides such as tetramethylene-bis(t-butylcarbodiimide) and cyclohexane-bis(methylene-t-butylcarbodiimide); aromatic biscarbodiimides such as phenylene-bis(xylylcarbodiimide); aliphatic polycarbodiimides such as polyhexamethylenecarbodiimide, polytrimethylhexamethylenecarbodiimide, polycyclohexylenecarbodiimide, poly(methylenebiscyclohexylenecarbodiimide), and poly(isophoronecarbodiimide); Examples of polycarbodiimides include aromatic polycarbodiimides such as poly(naphthylenecarbodiimide), poly(tolylenecarbodiimide), poly(methyldiisopropylphenylenecarbodiimide), poly(triethylphenylenecarbodiimide), poly(diethylphenylenecarbodiimide), poly(triisopropylphenylenecarbodiimide), poly(diisopropylphenylenecarbodiimide), poly(xylylenecarbodiimide), poly(tetramethylxylylenecarbodiimide), poly(methylenediphenylenecarbodiimide), and poly[methylenebis(methylphenylene)carbodiimide].

Commercially available carbodiimide curing agents include, for example, "Carbodilite V-02B," "Carbodilite V-03," "Carbodilite V-04K," "Carbodilite V-07," and "Carbodilite V-09" manufactured by Nisshinbo Chemical Co., Ltd.; and "Stavaxol P," "Stavaxol P400," and "Hi-Kasil 510" manufactured by Rhein Chemie.

The amine-based curing agent is a curing agent having two or more amino groups, and examples thereof include aliphatic amines, polyether amines, alicyclic amines, aromatic amines, etc., among which aromatic amines are preferred from the viewpoint of achieving the desired effects of the present invention. The amine-based curing agent is preferably a primary amine or a secondary amine, and more preferably a primary amine. Specific examples of amine-based curing agents include 4,4'-methylenebis(2,6-dimethylaniline), 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, m-phenylenediamine, m-xylylenediamine, diethyltoluenediamine, 4,4'-diaminodiphenylether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxybenzidine, 2,2-bis(3-amino-4-hydroxyphenyl)propane, and the like. propane, 3,3-dimethyl-5,5-diethyl-4,4-diphenylmethanediamine, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis(4-(4-aminophenoxy)phenyl)sulfone, bis(4-(3-aminophenoxy)phenyl)sulfone, and the like. Commercially available amine-based curing agents may be used, such as "SEIKACURE-S" manufactured by Seika Corporation, "KAYABOND C-200S", "KAYABOND C-100", "KAYAHARD A-A", "KAYAHARD A-B", and "KAYAHARD A-S" manufactured by Nippon Kayaku Co., Ltd., and "Epicure W" manufactured by Mitsubishi Chemical Corporation.

Specific examples of benzoxazine-based curing agents include "JBZ-OP100D" and "ODA-BOZ" manufactured by JFE Chemical Corporation; "HFB2006M" manufactured by Showa Polymer Co., Ltd.; and "P-d" and "F-a" manufactured by Shikoku Chemical Industry Co., Ltd.

Examples of cyanate ester curing agents include bifunctional cyanate resins such as bisphenol A dicyanate, polyphenol cyanate (oligo(3-methylene-1,5-phenylene cyanate)), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylidene diphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanate)phenylpropane, 1,1-bis(4-cyanate phenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanate phenyl-1-(methylethylidene))benzene, bis(4-cyanate phenyl)thioether, and bis(4-cyanate phenyl)ether; polyfunctional cyanate resins derived from phenol novolac and cresol novolac; and prepolymers in which these cyanate resins have been partially converted to triazine. Specific examples of cyanate ester-based hardeners include Lonza Japan's "PT30" and "PT60" (both of which are phenol novolac-type multifunctional cyanate ester resins), "BA230" and "BA230S75" (prepolymers in which part or all of bisphenol A dicyanate has been converted to triazine and formed into a trimer).

Thiol-based curing agents are curing agents that have two or more mercapto groups, and examples of such curing agents include trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), and tris(3-mercaptopropyl)isocyanurate.

The reactive group equivalent of other curing agents is preferably 50 g/eq. to 3000 g/eq., more preferably 100 g/eq. to 1000 g/eq., even more preferably 100 g/eq. to 500 g/eq., and particularly preferably 100 g/eq. to 300 g/eq. The reactive group equivalent is the mass of the curing agent per equivalent of reactive group. For example, in the case of a phenol-based curing agent, the reactive group is a phenolic hydroxyl group. In the case of an acid anhydride-based curing agent, one equivalent of a carboxylic anhydride group (-CO-O-CO-) corresponds to two equivalents of reactive groups.

From the viewpoint of obtaining a significant effect of the present invention, the content of the specific bisphenol-based curing agent A or the specific bisphenol-based curing agent B in the (A) curing agent is preferably 50% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 100% by mass, when the total amount of the (A) curing agent is taken as 100% by mass.

From the viewpoint of obtaining a significant effect of the present invention, the content of the (A) curing agent in the resin composition is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 1% by mass or more, and particularly preferably 3% by mass or more, and is preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 15% by mass or less, and particularly preferably 10% by mass or less, when the non-volatile components in the resin composition are taken as 100% by mass.

<(B) Epoxy Resin>
The resin composition of the present invention contains an epoxy resin (B). The epoxy resin (B) means a curable resin having an epoxy group. The epoxy resin (B) may be used alone or in combination of two or more kinds.

(B) Examples of epoxy resins include bixylenol type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bisphenol AF type epoxy resins, hydrogenated bisphenol A type epoxy resins, dicyclopentadiene type epoxy resins, trisphenol type epoxy resins, naphthol novolac type epoxy resins, phenol novolac type epoxy resins, tert-butyl-catechol type epoxy resins, naphthalene type epoxy resins, naphthol type epoxy resins, anthracene type epoxy resins, glycidylamine type epoxy resins, and glycidyl estherin type epoxy resins. terephthalate type epoxy resins, cresol novolac type epoxy resins, phenol aralkyl type epoxy resins, biphenyl type epoxy resins, linear aliphatic epoxy resins, epoxy resins having a butadiene structure, alicyclic epoxy resins, heterocyclic epoxy resins, spiro ring-containing epoxy resins, cyclohexane type epoxy resins, cyclohexane dimethanol type epoxy resins, naphthylene ether type epoxy resins, trimethylol type epoxy resins, tetraphenylethane type epoxy resins, isocyanurate type epoxy resins, phenolphthalimidine type epoxy resins, phenolphthalein type epoxy resins, etc.

The resin composition preferably contains, as the epoxy resin (B), an epoxy resin having two or more epoxy groups in one molecule. The proportion of the epoxy resin having two or more epoxy groups in one molecule relative to 100% by mass of the non-volatile components of the epoxy resin (B) is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more.

Epoxy resins include epoxy resins that are solid at a temperature of 25°C (hereinafter sometimes referred to as "solid epoxy resins") and epoxy resins that are liquid at a temperature of 25°C (hereinafter sometimes referred to as "liquid epoxy resins"). The resin composition of the present invention may contain only solid epoxy resins as the epoxy resin (B), or may contain only liquid epoxy resins, or may contain a combination of solid and liquid epoxy resins.

As the solid epoxy resin, a solid epoxy resin having three or more epoxy groups in one molecule is preferable, and an aromatic solid epoxy resin having three or more epoxy groups in one molecule is more preferable.

Preferred solid epoxy resins are bixylenol type epoxy resins, naphthalene type epoxy resins, naphthalene type tetrafunctional epoxy resins, naphthol novolac type epoxy resins, cresol novolac type epoxy resins, dicyclopentadiene type epoxy resins, trisphenol type epoxy resins, naphthol type epoxy resins, biphenyl type epoxy resins, naphthylene ether type epoxy resins, anthracene type epoxy resins, bisphenol A type epoxy resins, bisphenol AF type epoxy resins, phenol aralkyl type epoxy resins, tetraphenylethane type epoxy resins, phenolphthalimidine type epoxy resins, and phenolphthalein type epoxy resins.

Specific examples of solid epoxy resins include DIC's "HP4032H" (naphthalene type epoxy resin); DIC's "HP-4700" and "HP-4710" (naphthalene type tetrafunctional epoxy resin); DIC's "N-690" (cresol novolac type epoxy resin); DIC's "N-695" (cresol novolac type epoxy resin); DIC's "HP-7200", "HP-7200HH", "HP-7200H", and "HP-7200L" (dicyclopentadiene type epoxy resin); DIC's "EXA-73 11", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", "HP6000" (naphthylene ether type epoxy resin); "EPPN-502H" (trisphenol type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC7000L" (naphthol novolac type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC3000H", "NC3000", "NC3000L", "NC3000FH", "NC3100" (biphenyl type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "ESN475V" manufactured by Nippon Steel Chemical & Material Co., Ltd. (naphthalene type epoxy resin); "ESN485" (naphthol type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "ESN375" (dihydroxynaphthalene type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YX4000H", "YX4000", "YX4000HK", "YL7890" (bixylenol type epoxy resin) manufactured by Mitsubishi Chemical Co., Ltd.; "YL6121" (biphenyl type epoxy resin) manufactured by Mitsubishi Chemical Co., Ltd.; "YX8800" (anthracene type epoxy resin) manufactured by Mitsubishi Chemical Co., Ltd.; "YX77" manufactured by Mitsubishi Chemical Co., Ltd. 00" (phenol aralkyl type epoxy resin); "PG-100" and "CG-500" manufactured by Osaka Gas Chemicals; "YX7760" (bisphenol AF type epoxy resin) manufactured by Mitsubishi Chemical; "YL7800" (fluorene type epoxy resin) manufactured by Mitsubishi Chemical; "jER1010" (bisphenol A type epoxy resin) manufactured by Mitsubishi Chemical; "jER1031S" (tetraphenylethane type epoxy resin) manufactured by Mitsubishi Chemical; "WHR991S" (phenolphthalimidine type epoxy resin) manufactured by Nippon Kayaku Co., Ltd. These may be used alone or in combination of two or more types.

Preferably, the liquid epoxy resin has two or more epoxy groups in one molecule.

Preferred liquid epoxy resins are bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AF type epoxy resins, hydrogenated bisphenol A type epoxy resins, naphthalene type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, phenol novolac type epoxy resins, alicyclic epoxy resins having an ester skeleton, cyclohexane type epoxy resins, cyclohexane dimethanol type epoxy resins, and epoxy resins having a butadiene structure.

Specific examples of liquid epoxy resins include DIC's "HP4032", "HP4032D", and "HP4032SS" (naphthalene type epoxy resins); Mitsubishi Chemical's "828US", "828EL", "jER828EL", "825", and "jER828EL" (bisphenol A type epoxy resins); Mitsubishi Chemical's "jER807" and "1750" (bisphenol F type epoxy resins); Mitsubishi Chemical's "jER152" (phenol novolac type epoxy resin); Mitsubishi Chemical's "630", "630LSD", and "604" (glycidylamine type epoxy resins); ADEKA's "ED-523T" (glycirol type epoxy resin); ADEKA's "EP-3950L" and "EP-3980S" (glycidylamine type epoxy resins); A Examples of such epoxy resins include "EP-4088S" (dicyclopentadiene type epoxy resin) manufactured by DEKA Corporation; "ZX1059" (mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "EX-721" (glycidyl ester type epoxy resin) manufactured by Nagase Chemtex Corporation; "Celloxide 2021P" (alicyclic epoxy resin having an ester skeleton) manufactured by Daicel Corporation; "PB-3600" manufactured by Daicel Corporation, "JP-100" and "JP-200" (epoxy resin having a butadiene structure) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "ZX1658" and "ZX1658GS" (1,4-glycidylcyclohexane type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; and "YX8000" (hydrogenated bisphenol A type epoxy resin) manufactured by Mitsubishi Chemical Corporation. These may be used alone or in combination of two or more types.

The (B) epoxy resin may be a solid epoxy resin, a liquid epoxy resin, or a combination thereof, but it is preferable that it contains a solid epoxy resin, and it is particularly preferable that it is a combination of a solid epoxy resin and a liquid epoxy resin.

When a combination of a solid epoxy resin and a liquid epoxy resin is used as the (B) epoxy resin, the mass ratio thereof (solid epoxy resin:liquid epoxy resin) is preferably 20:1 to 1:20, more preferably 10:1 to 1:10, and particularly preferably 3:1 to 1:3.

The epoxy equivalent of the (B) epoxy resin is preferably 50 g/eq. to 5,000 g/eq., more preferably 60 g/eq. to 1,000 g/eq., even more preferably 80 g/eq. to 500 g/eq., and even more preferably 100 g/eq. to 300 g/eq. The epoxy equivalent is the mass of the resin per equivalent of epoxy groups. This epoxy equivalent can be measured according to JIS K7236.

The weight average molecular weight (Mw) of the (B) epoxy resin is preferably 100 to 5,000, more preferably 250 to 3,000, and even more preferably 400 to 1,500. The weight average molecular weight of the resin can be measured by gel permeation chromatography (GPC) as a polystyrene-equivalent value.

From the viewpoint of obtaining a significant effect of the present invention, the content of (B) epoxy resin is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, and particularly preferably 15% by mass or more, and is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 35% by mass or less, and particularly preferably 30% by mass or less, when the non-volatile components in the resin composition are taken as 100% by mass.

The mass ratio of the (A) curing agent to the (B) epoxy resin (mass of the (A) component/mass of the (B) component) is preferably 0.01 or more, more preferably 0.05 or more, even more preferably 0.1 or more, particularly preferably 0.2 or more, and is preferably 2.0 or less, more preferably 1.0 or less, even more preferably 0.5 or less, particularly preferably 0.3 or less.

<(C) White Inorganic Pigment>
The resin composition of the present invention contains a white inorganic pigment (C). In one embodiment, the white inorganic pigment (C) refers to an inorganic compound having a reflectance of 90% or more for light with a wavelength of 500 nm. The white inorganic pigment (C) does not contain silica. The white inorganic pigment (C) has a function of improving reflectance. The white inorganic pigment (C) may be used alone or in combination of two or more kinds.

(C) Examples of white inorganic pigment materials include white metal oxides such as aluminum oxide (alumina), titanium oxide, zirconium oxide, magnesium oxide, zinc oxide, cerium oxide, antimony oxide, tin oxide, barium titanate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, barium titanate zirconate, barium zirconate, and calcium zirconate; white metal sulfides such as zinc sulfide and strontium sulfide; white metal hydroxides such as aluminum hydroxide, magnesium hydroxide, and calcium hydroxide; white metal nitrides such as boron nitride, aluminum nitride, and manganese nitride; calcium carbonate, carbonate Examples of the white metal carbonates include barium, magnesium carbonate, strontium carbonate, and lead carbonate; white metal sulfates include barium sulfate, calcium sulfate, and lead sulfate; white metal phosphates include zinc phosphate, titanium phosphate, zirconium phosphate, and zirconium tungstate phosphate; white metal borates include aluminum borate; and white minerals such as cordierite, talc, clay, mica, hydrotalcite, and boehmite. Among these, it is preferable to select from aluminum oxide, titanium oxide, zirconium oxide, magnesium oxide, barium titanate, zinc oxide, cerium oxide, and calcium carbonate, and titanium oxide is particularly suitable. As the titanium oxide, any of rutile type, anatase type, and brookite type may be used, and among them, rutile type is preferable from the viewpoint of further improving the reflectance and the reflectance after the heat resistance test. Titanium oxide obtained by a method such as a sulfuric acid method or a chlorine method can be used. The material of the white inorganic pigment (C) may be one type alone or a mixture of two or more types. (C) The shape of the white inorganic pigment may be, for example, irregular, crushed, scaly, or spherical.

(C) Commercially available white inorganic pigments include, for example, "PX3788" manufactured by Sakai Chemical Industry Co., Ltd.; Typec "CR-50", "CR-57", "CR-80", "CR-90", "CR-93", "CR-95", "CR-97", "CR-60", "CR-63", "CR-67", "CR-58", "CR-85", and "UT771" manufactured by Ishihara Sangyo Kaisha; Typepure "R-100", "R-101", "R-102", "R-103", "R-104", "R-105", "R-108", "R-900", "R-902", "R-960", "R-706", and "R-931" manufactured by DuPont; "AHP300" manufactured by Nippon Light Metal Co., Ltd.; and Alnabeads "CB-P05" and "CB-A30S" manufactured by Showa Denko KK.

The specific surface area of the (C) white inorganic pigment is preferably 0.5 m ² /g or more, more preferably 1 m ² /g or more, and particularly preferably 2 m ² /g or more. There is no particular upper limit, but it is preferably 80 m ² /g or less, 70 m ² /g or less, or 60 m ² /g or less. The specific surface area is obtained according to the BET method by adsorbing nitrogen gas onto the surface of a sample using a specific surface area measuring device (Macsorb HM-1210 manufactured by Mountech Co., Ltd.) and calculating the specific surface area using the BET multipoint method.

The average particle size of the (C) white inorganic pigment is preferably 0.01 μm or more, more preferably 0.05 μm or more, and even more preferably 0.1 μm or more, from the viewpoint of significantly obtaining the desired effects of the present invention, and is preferably 5 μm or less, more preferably 2 μm or less, and even more preferably 1 μm or less.

The average particle size of the (C) white inorganic pigment can be measured by a laser diffraction/scattering method based on the Mie scattering theory. Specifically, a particle size distribution of the (C) white inorganic pigment is created on a volume basis using a laser diffraction/scattering particle size distribution measuring device, and the median diameter is used as the average particle size. The measurement sample can be prepared by weighing 100 mg of the (C) white inorganic pigment and 10 g of methyl ethyl ketone into a vial and dispersing the mixture ultrasonically for 10 minutes. The measurement sample is measured using a laser diffraction particle size distribution measuring device with blue and red light wavelengths as the light source, and the volume-based particle size distribution of the (C) white inorganic pigment is measured using a flow cell method, and the average particle size can be calculated as the median diameter from the particle size distribution obtained. An example of a laser diffraction particle size distribution measuring device is the "LA-960" manufactured by Horiba, Ltd.

(C) The white inorganic pigment is preferably treated with a surface treatment agent from the viewpoint of improving moisture resistance and dispersibility. The surface treatment agent may be used alone or in any combination of two or more types. Examples of the surface treatment agent include silane coupling agents such as vinyl silane coupling agents, epoxy silane coupling agents, styryl silane coupling agents, (meth)acrylic silane coupling agents, amino silane coupling agents, isocyanurate silane coupling agents, ureido silane coupling agents, mercapto silane coupling agents, isocyanate silane coupling agents, acid anhydride silane coupling agents, alkyl silane coupling agents, and phenyl silane coupling agents. From the viewpoint of improving reflectance and suppressing yellowing and deterioration of copper adhesion, the surface treatment agent is preferably a silane coupling agent that does not contain a nitrogen atom, and is particularly preferably a silane coupling agent selected from a phenyl silane coupling agent, an alkyl silane coupling agent, an epoxy silane coupling agent, a vinyl silane coupling agent, a (meth)acrylic silane coupling agent, and a styryl silane coupling agent.

Examples of phenyl silane coupling agents include phenyl trimethoxy silane and phenyl triethoxy silane. Examples of alkyl silane coupling agents include methyl trimethoxy silane, dimethyl dimethoxy silane, methyl triethoxy silane, dimethyl diethoxy silane, n-propyl trimethoxy silane, n-propyl triethoxy silane, hexyl trimethoxy silane, hexyl triethoxy silane, octyl triethoxy silane, decyl trimethoxy silane, and 1,6-bis (trimethoxy silyl) hexane. Examples of epoxy silane coupling agents include 2- (3,4-epoxy cyclohexyl) ethyl trimethoxy silane, 3-glycidoxy propyl methyl dimethoxy silane, 3-glycidoxy propyl trimethoxy silane, 3-glycidoxy propyl methyl diethoxy silane, and 3-glycidoxy propyl triethoxy silane.

Examples of vinyl-based silane coupling agents include vinyltrimethoxysilane and vinyltriethoxysilane. Examples of (meth)acrylic-based silane coupling agents include 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3-acryloxypropyltrimethoxysilane. Examples of styryl-based silane coupling agents include p-styryltrimethoxysilane.

Commercially available surface treatment agents include, for example, "KBM-103" and "KBE-103" (phenyl silane coupling agents) manufactured by Shin-Etsu Chemical Co., Ltd.; "KBM-13", "KBM-22", "KBE-13", "KBE-22", "KBM-3033", "KBE-3033", "KBM-3063", "KBE-3063", "KBE-3083", "KBM-3103C", "KBM-3066", and "KBM-7103" (alkyl silane coupling agents); -1003", "KBE-1003" (vinyl-based silane coupling agent); "KBM-303", "KBM-402", "KBM-403", "KBE-402", "KBE-403" (epoxy-based silane coupling agent); "KBM-1403" (styryl-based silane coupling agent); "KBM-502", "KBM-503", "KBE-502", "KBE-503", "KBM-5103" ((meth)acrylic silane coupling agent), etc.

From the viewpoint of improving the dispersibility of the (C) white inorganic pigment, it is preferable that the degree of surface treatment with the surface treatment agent falls within a specified range. Specifically, it is preferable that 100 parts by mass of the (C) white inorganic pigment is surface-treated with 0.2 parts by mass to 5 parts by mass of the surface treatment agent, it is preferable that it is surface-treated with 0.2 parts by mass to 3 parts by mass, and it is preferable that it is surface-treated with 0.3 parts by mass to 2 parts by mass.

The degree of surface treatment by the surface treatment agent can be evaluated by the amount of carbon per unit surface area of the white inorganic pigment (C). From the viewpoint of improving the dispersibility of the white inorganic pigment (C), the amount of carbon per unit surface area of the white inorganic pigment (C) is preferably 0.02 mg/m ² or more, more preferably 0.1 mg/m ² or more, and even more preferably 0.2 mg/m ² or more. On the other hand, from the viewpoint of suppressing an increase in the melt viscosity of the resin varnish and the melt viscosity in the sheet form, it is preferably 1 mg/m ² or less, more preferably 0.8 mg/m ² or less, and even more preferably 0.5 mg/m ² or less.

The amount of carbon per unit surface area of the (C) white inorganic pigment can be measured after the surface-treated (C) white inorganic pigment is washed with a solvent (e.g., methyl ethyl ketone (MEK)). Specifically, a sufficient amount of MEK as a solvent is added to the (C) white inorganic pigment that has been surface-treated with a surface treatment agent, and ultrasonic cleaning is performed at 25°C for 5 minutes. After removing the supernatant and drying the solids, the amount of carbon per unit surface area of the (C) white inorganic pigment can be measured using a carbon analyzer. An example of a carbon analyzer that can be used is the "EMIA-320V" manufactured by Horiba, Ltd.

In order to obtain a significant effect of the present invention, the content of the (C) white inorganic pigment is preferably 1% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, and particularly preferably 25% by mass or more, based on 100% by mass of the non-volatile components in the resin composition, and is preferably 80% by mass or less, more preferably 70% by mass or less or 60% by mass or less, even more preferably 50% by mass or less or 40% by mass or less, and particularly preferably 30% by mass or less.

The mass ratio of the white inorganic pigment (C) to the epoxy resin (B) (mass of component (C)/mass of component (B)) is preferably 0.2 or more, more preferably 0.5 or more, even more preferably 0.8 or more, particularly preferably 1.0 or more, and is preferably 5.0 or less, more preferably 3.0 or less, even more preferably 2.0 or less, particularly preferably 1.8 or less.

<(D) Silica>
The resin composition of the present invention may contain (D) silica as an optional component.

(D) Silica includes, for example, amorphous silica, fused silica, crystalline silica, synthetic silica, hollow silica, etc. In addition, as (D) silica, spherical silica is preferable. The specific surface area and average particle size of (D) silica are the same as those of (C) white inorganic pigment. (D) Silica may be used alone or in combination of two or more types.

(D) Commercially available silica products include, for example, "UFP-30" manufactured by Denka; "SP60-05" and "SP507-05" manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YC100C", "YA050C", "YA050C-MJE", and "YA010C" manufactured by Admatechs; "Silfil NSS-3N", "Silfil NSS-4N", and "Silfil NSS-5N" manufactured by Tokuyama Corporation; "SC2500SQ", "SO-C4", "SO-C2", and "SO-C1" manufactured by Admatechs; and the like.

From the viewpoint of improving moisture resistance and dispersibility, it is preferable that (D) silica is treated with a surface treatment agent. Examples of the surface treatment agent include the same as the surface treatment agent for (C) white inorganic pigment. The degree of surface treatment of (D) silica with the surface treatment agent is the same as that of (C) white inorganic pigment.

In order to obtain a significant effect of the present invention, the content of (D) silica is preferably 70% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less, and particularly preferably 35% by mass or less, when the non-volatile components in the resin composition are taken as 100% by mass, and may be, for example, 0% by mass or more, 1% by mass or more, 5% by mass or more, 10% by mass or more, 15% by mass or more, 20% by mass or more, etc.

From the viewpoint of suppressing cracks while maintaining high reflectance, the total content of (C) white inorganic pigment and (D) silica is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, and particularly preferably 50% by mass or more, and is preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 75% by mass or less, and particularly preferably 70% by mass or less, when the non-volatile components in the resin composition are taken as 100% by mass.

The mass ratio of (D) silica to (C) white inorganic pigment (mass of (D) component/mass of (C) component) is, for example, 0 or more, preferably 0.1 or more, more preferably 0.2 or more, even more preferably 0.5 or more, particularly preferably 0.8 or more, from the viewpoint of suppressing cracks while maintaining high reflectance, and is preferably 20.0 or less, more preferably 10.0 or less, even more preferably 5.0 or less, particularly preferably 2.0 or less.

<(E) Curing Accelerator>
The resin composition of the present invention may contain a curing accelerator (E) as an optional component. The curing accelerator (E) has a function of accelerating the curing reaction of the epoxy resin (A). The curing accelerator (E) may be used alone or in combination of two or more kinds.

(E) Examples of the curing accelerator include phosphorus-based curing accelerators, imidazole-based curing accelerators, amine-based curing accelerators, guanidine-based curing accelerators, and metal-based curing accelerators. Among them, as the (E) curing accelerator, from the viewpoint of achieving a higher reflectance, phosphorus-based curing accelerators and imidazole-based curing accelerators are preferred, and phosphorus-based curing accelerators are more preferred.

From the viewpoint of achieving a higher reflectance, it is preferable that the phosphorus-based curing accelerator contains one or more selected from the group consisting of phosphonium salts and phosphines.

Examples of phosphonium salts include aliphatic phosphonium salts such as tetrabutylphosphonium bromide, tetrabutylphosphonium chloride, tetrabutylphosphonium acetate, tetrabutylphosphonium decanoate, tetrabutylphosphonium laurate, bis(tetrabutylphosphonium)pyromellitate, tetrabutylphosphonium hydrogenhexahydrophthalate, tetrabutylphosphonium 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenolate, and di-tert-butylmethylphosphonium tetraphenylborate; methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, propyltriphenylphosphonium bromide, butyltriphenylphosphonium bromide, and the like. Examples of aromatic phosphonium salts include phenylphosphonium bromide, benzyltriphenylphosphonium chloride, tetraphenylphosphonium bromide, p-tolyltriphenylphosphonium tetra-p-tolylborate, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra-p-tolylborate, triphenylethylphosphonium tetraphenylborate, tris(3-methylphenyl)ethylphosphonium tetraphenylborate, tris(2-methoxyphenyl)ethylphosphonium tetraphenylborate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, and butyltriphenylphosphonium thiocyanate.

Examples of phosphines include aliphatic phosphines such as tributylphosphine, tri-tert-butylphosphine, trioctylphosphine, di-tert-butyl(2-butenyl)phosphine, di-tert-butyl(3-methyl-2-butenyl)phosphine, and tricyclohexylphosphine; dibutylphenylphosphine, di-tert-butylphenylphosphine, methyldiphenylphosphine, ethyldiphenylphosphine, butyldiphenylphosphine, diphenylcyclohexylphosphine, triphenylphosphine, tri-o-tolylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, tris(4-ethylphenyl)phosphine, tris(4-propylphenyl)phosphine, tris(4-isopropylphenyl)phosphine, tris(4-butylphenyl)phosphine, tris(4-tert-butylphenyl)phosphine, tris(2,4-dimethylphenyl)phosphine, and tris(2,5-dimethylphenyl)phosphine. tris(2,6-dimethylphenyl)phosphine, tris(3,5-dimethylphenyl)phosphine, tris(2,4,6-trimethylphenyl)phosphine, tris(2,6-dimethyl-4-ethoxyphenyl)phosphine, tris(2-methoxyphenyl)phosphine, tris(4-methoxyphenyl)phosphine, tris(4-ethoxyphenyl)phosphine, tris(4-tert-butoxyphenyl)phosphine, diphenyl-2-pyridylphosphine, 1,2-biphenylphosphine, Examples of such aromatic phosphines include bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, 1,2-bis(diphenylphosphino)acetylene, and 2,2'-bis(diphenylphosphino)diphenylether; aromatic phosphine-borane complexes such as triphenylphosphine-triphenylborane; and aromatic phosphine-quinone adducts such as triphenylphosphine-p-benzoquinone adducts.

Commercially available phosphorus-based curing accelerators may be used, such as "TBP-DA" manufactured by Hokko Chemical Industry Co., Ltd.

Examples of imidazole-based curing accelerators include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4 -diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl Examples of the imidazole compounds include 1-dodecyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, 2-phenylimidazoline, and adducts of imidazole compounds and epoxy resins, with 2-ethyl-4-methylimidazole and 1-benzyl-2-phenylimidazole being preferred.

Commercially available imidazole curing accelerators may be used, such as "P200-H50" manufactured by Mitsubishi Chemical Corporation and "1B2PZ-10M" manufactured by Shikoku Kasei Co., Ltd.

Examples of amine-based curing accelerators include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, and 1,8-diazabicyclo(5,4,0)-undecene, with 4-dimethylaminopyridine and 1,8-diazabicyclo(5,4,0)-undecene being preferred.

Examples of guanidine-based curing accelerators include dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene. Examples include o[4.4.0]dec-5-ene, 1-methylbiguanide, 1-ethylbiguanide, 1-n-butylbiguanide, 1-n-octadecylbiguanide, 1,1-dimethylbiguanide, 1,1-diethylbiguanide, 1-cyclohexylbiguanide, 1-allylbiguanide, 1-phenylbiguanide, and 1-(o-tolyl)biguanide, and dicyandiamide and 1,5,7-triazabicyclo[4.4.0]dec-5-ene are preferred.

Metal-based curing accelerators include, for example, organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, and tin. Specific examples of organometallic complexes include organocobalt complexes such as cobalt (II) acetylacetonate and cobalt (III) acetylacetonate, organocopper complexes such as copper (II) acetylacetonate, organozinc complexes such as zinc (II) acetylacetonate, organoiron complexes such as iron (III) acetylacetonate, organonickel complexes such as nickel (II) acetylacetonate, and organomanganese complexes such as manganese (II) acetylacetonate. Organometallic salts include, for example, zinc octylate, tin octylate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

In order to obtain a significant effect of the present invention, the content of the curing accelerator (E) is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, and particularly preferably 0.8% by mass or less, when the non-volatile components in the resin composition are taken as 100% by mass, and for example, 0% by mass or more, 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and particularly preferably 0.1% by mass or more.

<(F) Thermoplastic resin>
The resin composition of the present invention may contain a thermoplastic resin (F) as an optional component. The thermoplastic resin (F) may be used alone or in combination of two or more kinds. It may be used.

(F) Examples of thermoplastic resins include phenoxy resins, polyvinyl acetal resins, acrylic resins, polyolefin resins, polybutadiene resins, polyimide resins, polyamideimide resins, polysulfone resins, polyethersulfone resins, polyphenylene ether resins, polyetherimide resins, polycarbonate resins, polyetheretherketone resins, and polyester resins. Among these, resins selected from phenoxy resins, acrylic resins, and polyphenylene ether resins are preferred.

Examples of phenoxy resins include phenoxy resins having one or more skeletons selected from the group consisting of bisphenol A skeleton, bisphenol F skeleton, bisphenol S skeleton, bisphenolacetophenone skeleton, novolac skeleton, biphenyl skeleton, fluorene skeleton, dicyclopentadiene skeleton, norbornene skeleton, naphthalene skeleton, anthracene skeleton, adamantane skeleton, terpene skeleton, and trimethylcyclohexane skeleton. The terminal of the phenoxy resin may be any functional group such as a phenolic hydroxyl group or an epoxy group. The phenoxy resin may be used alone or in combination of two or more types. Specific examples of phenoxy resins include "1256" and "4250" (both phenoxy resins containing a bisphenol A skeleton), "YX8100" (phenoxy resin containing a bisphenol S skeleton), and "YX6954" (phenoxy resin containing a bisphenol acetophenone skeleton) manufactured by Mitsubishi Chemical Corporation, "FX280" and "FX293" manufactured by Nippon Steel Chemical & Material Co., Ltd., and "YX7200B35", "YL7500BH30", "YX6954BH30", "YX7553", "YX7553BH30", "YL7769BH30", "YL6794", "YL7213", "YL7290", and "YL7482" manufactured by Mitsubishi Chemical Corporation.

Examples of polyvinyl acetal resins include polyvinyl formal resins and polyvinyl butyral resins, with polyvinyl butyral resins being preferred. Specific examples of polyvinyl acetal resins include Denka Butyral 4000-2, Denka Butyral 5000-A, Denka Butyral 6000-C, and Denka Butyral 6000-EP, all manufactured by Denki Kagaku Kogyo Co., Ltd., and the S-LEC BH series, BX series (e.g. BX-5Z), KS series (e.g. KS-1), BL series, and BM series, all manufactured by Sekisui Chemical Co., Ltd.

Acrylic resin refers to a polymer obtained by polymerizing monomer components including (meth)acrylic acid ester monomers. The monomer components constituting the acrylic resin may contain, in addition to (meth)acrylic acid ester monomers, (meth)acrylamide monomers, styrene monomers, functional group-containing monomers, etc. as copolymerization components. Specific examples of acrylic resins include "ARUFON UP-1000", "ARUFON UP-1010", "ARUFON UP-1020", "ARUFON UP-1021", "ARUFON UP-1061", "ARUFON UP-1080", "ARUFON UP-1110", "ARUFON UP-1170", "ARUFON UP-1190", "ARUFON UP-1500", "ARUFON UH-2000", "ARUFON UH-2041", "ARUFON UH-2190", "ARUFON UHE-2012", "ARUFON UC-3510", and "ARUFON UP-1021", all manufactured by Toagosei Co., Ltd. UG-4010, ARUFON US-6100, ARUFON US-6170, etc. These may be used alone or in combination of two or more.

Examples of polyolefin resins include ethylene-based copolymer resins such as low-density polyethylene, very low-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-methyl acrylate copolymer; and polyolefin-based elastomers such as polypropylene and ethylene-propylene block copolymer.

Examples of polybutadiene resins include hydrogenated polybutadiene skeleton-containing resins, hydroxyl group-containing polybutadiene resins, phenolic hydroxyl group-containing polybutadiene resins, carboxyl group-containing polybutadiene resins, acid anhydride group-containing polybutadiene resins, epoxy group-containing polybutadiene resins, isocyanate group-containing polybutadiene resins, urethane group-containing polybutadiene resins, polyphenylene ether-polybutadiene resins, etc.

Specific examples of polyimide resins include "Rikacoat SN20" and "Rikacoat PN20" manufactured by New Japan Chemical Co., Ltd. Specific examples of polyimide resins also include modified polyimides such as linear polyimides obtained by reacting bifunctional hydroxyl-terminated polybutadiene, a diisocyanate compound, and a tetrabasic acid anhydride (polyimides described in JP-A-2006-37083), and polysiloxane skeleton-containing polyimides (polyimides described in JP-A-2002-12667 and JP-A-2000-319386, etc.).

Specific examples of polyamide-imide resins include "Viromax HR11NN" and "Viromax HR16NN" manufactured by Toyobo Co., Ltd. Specific examples of polyamide-imide resins also include modified polyamide-imides such as "KS9100" and "KS9300" (polyamide-imide containing a polysiloxane skeleton) manufactured by Hitachi Chemical Co., Ltd.

A specific example of a polyethersulfone resin is "PES5003P" manufactured by Sumitomo Chemical Co., Ltd.

Specific examples of polysulfone resins include polysulfones "P1700" and "P3500" manufactured by Solvay Advanced Polymers, Inc.

Specific examples of polyphenylene ether resins include oligophenylene ether-styrene resins "OPE-2St1200" and "OPE-2St2200" manufactured by Mitsubishi Gas Chemical Co., Inc., and "NORYL SA90" manufactured by SABIC. Specific examples of polyetherimide resins include "Ultem" manufactured by GE.

Examples of polycarbonate resins include hydroxyl group-containing carbonate resins, phenolic hydroxyl group-containing carbonate resins, carboxyl group-containing carbonate resins, acid anhydride group-containing carbonate resins, isocyanate group-containing carbonate resins, and urethane group-containing carbonate resins. Specific examples of polycarbonate resins include "FPC0220" manufactured by Mitsubishi Gas Chemical Co., Ltd., "T6002" and "T6001" (polycarbonate diols) manufactured by Asahi Kasei Chemicals Corporation, and "C-1090", "C-2090", and "C-3090" (polycarbonate diols) manufactured by Kuraray Co., Ltd. Specific examples of polyether ether ketone resins include "Sumiploy K" manufactured by Sumitomo Chemical Co., Ltd. Examples of polyester resins include polyethylene terephthalate resins, etc.

The weight average molecular weight of the (F) thermoplastic resin is preferably 8,000 or more, more preferably 10,000 or more, even more preferably 20,000 or more, and is preferably 100,000 or less, more preferably 70,000 or less, even more preferably 60,000 or less. . The weight average molecular weight of the resin can be measured as a polystyrene-equivalent value by gel permeation chromatography (GPC).

(F) The thermoplastic resin is preferably a thermoplastic resin that, when formed into a film of 20 μm, has a transmittance of 80% or more for light with a wavelength of 450 nm incident perpendicularly to the film surface.

The content of (F) thermoplastic resin is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and particularly preferably 25% by mass or less, when the non-volatile components in the resin composition are taken as 100% by mass, and is, for example, 0% by mass or more, 0.1% by mass or more, preferably 1% by mass or more, more preferably 5% by mass or more, and particularly preferably 10% by mass or more.

<(G) Antioxidant>
The resin composition of the present invention may contain an antioxidant (G) as an optional component. The antioxidant (G) may be used alone or in combination of two or more kinds.

(G) Examples of the antioxidant include hindered phenol-based antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants. Among these, from the viewpoint of further increasing the reflectance after heat resistance treatment, hindered phenol-based antioxidants are preferred as the antioxidant.

(G) Specific examples of antioxidants include, for example, 2,6-di-tert-butyl-4-methylphenol, pentaerythritol tetrakis [3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, 2,4,6-tris(4-hydroxy-3,5-di-tert-butylbenzyl)mesitylene, 6-(4-hydroxy-3,5-di-tert-butylanilino)-2,4-bis(octylthio)-1,3,5-triazine, 2,2'-thiodiethylbis[3-( 3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,2-bis[3-(4-hydroxy-3,5-di-tert-butylphenyl)propionyl]hydrazine, 3-(4-hydroxy-3,5-diisopropylphenyl)octylpropionate, 4,6-bis(octylthiomethyl)-o-cresol, N,N'-hexamethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanamide], 1,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], etc.

(G) The antioxidant may be a commercially available product. Commercially available products of the antioxidant (G) include "BHT" manufactured by Wako Pure Chemical Industries, Ltd., and Irganox "1010", "3114", "1330", "565", "1035", "MD1024", "1135", "1520L", "1098", and "259" (hindered phenol-based antioxidants) manufactured by BASF Corporation.

The content of (G) antioxidant is preferably 0.5% by mass or less, more preferably 0.1% by mass or less, even more preferably 0.08% by mass or less, and particularly preferably 0.06% by mass or less, when the non-volatile components in the resin composition are taken as 100% by mass, and is, for example, 0% by mass or more, 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and particularly preferably 0.04% by mass or more.

<(H) Ultraviolet absorber>
From the viewpoint of further improving the light stability of the resin composition, the resin composition may further contain (H) an ultraviolet absorbing agent as an optional component.

(H) Examples of ultraviolet absorbers include benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, and salicylic acid-based ultraviolet absorbers. (F) The ultraviolet absorbers may be used alone or in combination of two or more.

Examples of benzophenone-based UV absorbers include 2-hydroxy-4-octyloxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxy-benzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, bis(2-methoxy-4-hydroxy-5-benzoylphenyl)methane, 2,2'-dihydroxy-4-methoxy-benzophenone, and 2,2'-dihydroxy-4,4'-dimethoxybenzophenone.

Examples of benzotriazole-based UV absorbers include 2-(2H-benzotriazol-2-yl)-4-methylphenol, 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, 2-(5-chloro-2H-benzotriazol-2-yl)-6-(1,1-dimethylethyl)-4-methylphenol, 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol, and 2,2'-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol].

Examples of salicylic acid-based ultraviolet absorbers include phenyl salicylate, 4-tert-butylphenyl 2-hydroxybenzoate, phenyl 2-hydroxybenzoate, 2,4-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate, and hexadecyl-3,5-di-tert-butyl-4-hydroxybenzoate.

(H) The ultraviolet absorber may be a commercially available product. (F) Examples of commercially available ultraviolet absorbers include "Chimassorb 81" and "Chimassorb 81 FL" (benzophenone-based ultraviolet absorbers) manufactured by BASF Corporation; "Tinuvin P", "Tinuvin 234", "Tinuvin 234 FF", "Tinuvin 326", "Tinuvin 326 FL", "Tinuvin 329", "Tinuvin 329 FL", and "Tinuvin 360" (benzotriazole-based ultraviolet absorbers) manufactured by BASF Corporation.

The content of (H) ultraviolet absorber is preferably 0.5% by mass or less, more preferably 0.1% by mass or less, even more preferably 0.08% by mass or less, and particularly preferably 0.06% by mass or less, when the non-volatile components in the resin composition are taken as 100% by mass, and is, for example, 0% by mass or more, 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and particularly preferably 0.04% by mass or more.

<(I) Other Additives>
The resin composition of the present invention may further contain any additive as a non-volatile component. Examples of such additives include organic fillers such as rubber particles; leveling agents such as silicone-based leveling agents and acrylic polymer-based leveling agents; thickeners such as bentone and montmorillonite; defoamers such as silicone-based defoamers, acrylic defoamers, fluorine-based defoamers, and vinyl resin-based defoamers; adhesion improvers such as urea silane; adhesion imparters such as triazole-based adhesion imparters, tetrazole-based adhesion imparters, and triazine-based adhesion imparters; fluorescent brighteners such as stilbene derivatives; surfactants such as fluorine-based surfactants and silicone-based surfactants; phosphorus-based flame retardants (e.g. Flame retardants such as phosphoric acid ester compounds, phosphazene compounds, phosphinic acid compounds, red phosphorus), nitrogen-based flame retardants (e.g. melamine sulfate), halogen-based flame retardants, and inorganic flame retardants (e.g. antimony trioxide); dispersants such as phosphoric acid ester dispersants, polyoxyalkylene dispersants, acetylene dispersants, silicone dispersants, anionic dispersants, and cationic dispersants; stabilizers such as borate stabilizers, titanate stabilizers, aluminate stabilizers, zirconate stabilizers, isocyanate stabilizers, carboxylic acid stabilizers, and carboxylic anhydride stabilizers. (I) Other additives may be used alone or in combination of two or more at any ratio. (I) The content of other additives can be appropriately set by a person skilled in the art.

<(J) Organic Solvent>
The resin composition of the present invention may further contain an arbitrary organic solvent as a volatile component in addition to the non-volatile components described above. As the (J) organic solvent, any known organic solvent may be appropriately used, and the type is not particularly limited. As the (J) organic solvent, for example, ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.; ester-based solvents such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, isoamyl acetate, methyl propionate, ethyl propionate, γ-butyrolactone, etc.; ether-based solvents such as tetrahydropyran, tetrahydrofuran, 1,4-dioxane, diethyl ether, diisopropyl ether, dibutyl ether, diphenyl ether, etc.; alcohol-based solvents such as methanol, ethanol, propanol, butanol, ethylene glycol, etc.; 2-ethoxyethyl acetate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl diglycol acetate, γ-butyrolactone, methyl methoxypropionate, etc. Examples of the organic solvent include ether ester solvents such as methyl lactate, ethyl lactate, and methyl 2-hydroxyisobutyrate; ester alcohol solvents such as 2-methoxypropanol, 2-methoxyethanol, 2-ethoxyethanol, propylene glycol monomethyl ether, and diethylene glycol monobutyl ether (butyl carbitol); amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; sulfoxide solvents such as dimethyl sulfoxide; nitrile solvents such as acetonitrile and propionitrile; aliphatic hydrocarbon solvents such as hexane, cyclopentane, cyclohexane, and methylcyclohexane; and aromatic hydrocarbon solvents such as benzene, toluene, xylene, ethylbenzene, and trimethylbenzene. The organic solvent (J) may be used alone or in combination of two or more in any ratio.

The content of (J) organic solvent is not particularly limited, but when all components in the resin composition are taken as 100% by mass, it can be, for example, 60% by mass or less, 40% by mass or less, 30% by mass or less, 20% by mass or less, 15% by mass or less, 10% by mass or less, 5% by mass or less, etc.

The method for preparing the resin composition of the present invention is not particularly limited, and examples include a method in which the components described above are added to any container and mixed and dispersed using a rotary mixer or the like.

<Physical properties and applications of resin composition>
According to the resin composition of the present invention, a cured product having excellent reflectance can be obtained. Therefore, the resin composition of the present invention can be suitably used as a resin composition (light reflecting resin composition) for obtaining a cured product for light reflection applications for reflecting light from a light source. Specifically, it can be suitably used as a resin composition for a reflective sheet application formed on the outermost layer of a printed wiring board. Examples of light sources include light emitting diodes (LEDs), mini LEDs, micro LEDs, and the like. In addition, the resin composition of the present invention can be suitably used as a resin composition for insulating the solder resist layer of a printed wiring board. Therefore, the resin composition of the present invention can be suitably used as a resin composition for forming a layer that serves both as a solder resist layer and a reflective sheet. Furthermore, the resin composition of the present invention can be suitably used as a resin composition for interlayer insulation of a printed wiring board. Therefore, the resin composition of the present invention can be suitably used as a resin composition for forming an interlayer insulating layer.

The resin composition of the present invention contains (A) a curing agent, (B) an epoxy resin, and (C) a white inorganic pigment, and (A) the curing agent contains a specific bisphenol-based curing agent. By using such a resin composition, it is possible to obtain a cured product that has excellent adhesion to the underlying wiring and excellent reflectance.

The cured product of the resin composition of the present invention may have high adhesion to the underlying wiring. Therefore, in one embodiment, when measured as in Test Example 1 below, the adhesion strength (copper foil peel strength calculated from the load when the laminated copper foil is peeled off in the vertical direction) of the cured product of the resin composition (cured product obtained by heating at 100°C for 30 minutes, then 180°C for 30 minutes, then 200°C for 90 minutes) to the copper substrate at room temperature (23°C) (before HAST (high-speed accelerated life test)) is preferably 0.3 kgf/cm or more, more preferably 0.5 kgf/cm or more, and even more preferably 0.8 kgf/cm or more, and furthermore, the adhesion strength (after HAST (high-speed accelerated life test)) of the cured product of the resin composition to the copper substrate at room temperature (23°C) after HAST (high-speed accelerated life test) (temperature 130°C, humidity 85% RH, 100 hours) can be preferably 0.2 kgf/cm or more, more preferably 0.3 kgf/cm or more, even more preferably 0.5 kgf/cm or more, and particularly preferably 0.7 kgf/cm or more.

The cured product of the resin composition of the present invention may have a high reflectance. Therefore, in one embodiment, the reflectance (before heat resistance test) of the cured product of the resin composition (cured product obtained by heating at 100°C for 30 minutes, then 180°C for 30 minutes, then 200°C for 90 minutes) to light with a wavelength of 460 nm when measured as in Test Example 2 below is preferably 80% or more, more preferably 85% or more, even more preferably 90% or more, and particularly preferably 95% or more, and the reflectance (after heat resistance test) of the cured product of the resin composition after a heat resistance test (temperature 125°C, 100 hours) to light with a wavelength of 460 nm may be preferably 75% or more, more preferably 80% or more, even more preferably 85% or more, and particularly preferably 90% or more.

[Resin sheet]
The resin sheet of the present invention includes a support and a resin composition layer formed from the resin composition of the present invention provided on the support.

The thickness of the resin composition layer is preferably 200 μm or less, more preferably 100 μm or less, and even more preferably 80 μm or less, from the viewpoint of making the printed wiring board thinner and being able to provide a cured product with excellent insulation even if the cured product of the resin composition is a thin film. The lower limit of the thickness of the resin composition layer is not particularly limited, but can usually be 5 μm or more, 10 μm or more, etc.

Examples of the support include films made of plastic materials, metal foils, and release paper, with films made of plastic materials and metal foils being preferred.

When a film made of a plastic material is used as the support, examples of the plastic material include polyesters such as polyethylene terephthalate (hereinafter sometimes abbreviated as "PET") and polyethylene naphthalate (hereinafter sometimes abbreviated as "PEN"), polycarbonate (hereinafter sometimes abbreviated as "PC"), acrylics such as polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, polyimide, etc. Among these, polyethylene terephthalate and polyethylene naphthalate are preferred, with inexpensive polyethylene terephthalate being particularly preferred.

When a metal foil is used as the support, examples of the metal foil include copper foil and aluminum foil, with copper foil being preferred. As the copper foil, a foil made of a single metal, copper, or an alloy of copper and another metal (e.g., tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.) may be used.

The support may be subjected to a matte treatment, corona treatment, or antistatic treatment on the surface that is to be bonded to the resin composition layer.

As the support, a support with a release layer having a release layer on the surface to be bonded to the resin composition layer may be used. Examples of the release agent used in the release layer of the support with a release layer include one or more release agents selected from the group consisting of alkyd resins, polyolefin resins, urethane resins, and silicone resins. The support with a release layer may be a commercially available product, and examples thereof include "PET501010", "SK-1", "AL-5", and "AL-7" manufactured by Lintec Corporation, which are PET films having a release layer mainly composed of an alkyd resin-based release agent; "Lumirror T60" manufactured by Toray Industries, Inc.; "Purex" manufactured by Teijin Limited; and "Unipeel" manufactured by Unitika Limited.

The thickness of the support is not particularly limited, but is preferably in the range of 5 μm to 75 μm, and more preferably in the range of 10 μm to 60 μm. When using a support with a release layer, it is preferable that the thickness of the entire support with the release layer is in the above range.

In one embodiment, the resin sheet may further include other layers as necessary. Examples of such other layers include a protective film similar to the support provided on the surface of the resin composition layer that is not bonded to the support (i.e., the surface opposite the support). The thickness of the protective film is not particularly limited, but is, for example, 1 μm to 40 μm. By laminating the protective film, it is possible to suppress adhesion of dirt and the like and scratches on the surface of the resin composition layer.

The resin sheet can be produced, for example, by preparing a resin varnish by dissolving the liquid resin composition in an organic solvent or by applying the resin varnish to a support using a die coater or the like, and then drying the varnish to form a resin composition layer.

The organic solvent may be the same as the organic solvent described as a component of the resin composition. The organic solvent may be used alone or in combination of two or more kinds.

Drying may be performed by known methods such as heating or blowing hot air. There are no particular limitations on the drying conditions, but drying is performed so that the content of organic solvent in the resin composition layer is 10% by mass or less, preferably 5% by mass or less. Although it varies depending on the boiling point of the organic solvent in the resin composition (resin varnish), for example, when using a resin composition (resin varnish) containing 30% by mass to 60% by mass of organic solvent, the resin composition layer can be formed by drying at 50°C to 150°C for 3 to 10 minutes.

The resin sheet can be stored in a roll. If the resin sheet has a protective film, it can be used by peeling off the protective film.

The resin composition of the present invention used in the resin composition layer has a low melt viscosity and therefore has excellent flexibility. Therefore, the resin sheet exhibits the property of having excellent flexibility. Specifically, when the resin sheet is folded 180° along an axis having a diameter of 1 mm so that the support is on the inside, cracking of the resin sheet is suppressed.

[Cured product]
The cured product of the present invention is obtained by curing the resin composition of the present invention. The curing conditions of the resin composition may be the conditions of step (II) described below. In addition, the resin composition may be preheated before curing, and heating may be performed multiple times including preheating.

[Reflective sheets, printed wiring boards]
The reflecting sheet of the present invention includes a cured product of the resin composition of the present invention. The printed wiring board of the present invention includes the reflecting sheet of the present invention. The printed wiring board of the present invention preferably includes the reflecting sheet as an interlayer insulating layer or a solder resist layer.

As shown in FIG. 1, the printed wiring board 1 has a reflective sheet 3 formed on a substrate 2, and a light source 4 such as a light-emitting diode (LED) is disposed on a surface 31 of the reflective sheet 3.

The reflective sheet contains a cured product of the resin composition of the present invention, and therefore can reflect light with a high reflectance. For example, the reflectance of light having a wavelength of 460 nm is preferably more than 85%, more preferably 90% or more, and even more preferably 92% or more. The upper limit of the reflectance can be 100% or less. In addition, the reflective sheet contains a cured product of the resin composition of the present invention, and therefore can reflect light with a high reflectance even after a heat resistance test (temperature 125°C, 100 hours) treatment. For example, the reflectance of light having a wavelength of 460 nm after the heat resistance test treatment is preferably more than 80%, more preferably 85% or more, and even more preferably 88% or more. The upper limit of the reflectance after the heat resistance test treatment can be 100% or less. The reflectance and the reflectance after the heat resistance test treatment can be measured, for example, using a multichannel spectrometer (MCPD-7700, manufactured by Otsuka Electronics Co., Ltd.).

The printed wiring board and the reflective sheet of the present invention can be produced, for example, by a method including the following steps (I), (II) and (III) using the above-mentioned resin sheet.
(I) a step of laminating the resin composition layer of the resin sheet on a substrate so that the resin composition layer is bonded to the substrate; (II) a step of thermally curing the resin composition layer to form a reflective sheet; and (III) a step of arranging a light source on the reflective sheet.

There are no limitations on the substrate used in step (I); for example, a circuit board having an insulating layer, a conductor layer formed on the insulating layer, and a solder resist layer formed on the conductor layer may be used.

The substrate and the resin sheet can be laminated, for example, by heat-pressing the resin sheet to the substrate from the support side. Examples of the member for heat-pressing the resin sheet to the substrate (hereinafter also referred to as the "heat-pressing member") include a heated metal plate (such as a SUS panel) or a metal roll (SUS roll). Note that rather than pressing the heat-pressing member directly onto the resin sheet, it is preferable to press it via an elastic material such as heat-resistant rubber so that the resin sheet can adequately follow the surface irregularities of the substrate.

The lamination of the substrate and the resin sheet may be performed by a vacuum lamination method. In the vacuum lamination method, the heat-pressure bonding temperature is preferably in the range of 60°C to 160°C, more preferably in the range of 80°C to 140°C, the heat-pressure bonding pressure is preferably in the range of 0.098MPa to 1.77MPa, more preferably in the range of 0.29MPa to 1.47MPa, and the heat-pressure bonding time is preferably in the range of 20 seconds to 400 seconds, more preferably in the range of 30 seconds to 300 seconds. The lamination is preferably performed under reduced pressure conditions of a pressure of 26.7hPa or less.

Lamination can be performed using a commercially available vacuum laminator. Examples of commercially available vacuum laminators include a vacuum pressure laminator manufactured by Meiki Seisakusho Co., Ltd., a vacuum applicator manufactured by Nikko Materials Co., Ltd., and a batch type vacuum pressure laminator.

After lamination, the laminated resin sheets may be smoothed under normal pressure (atmospheric pressure), for example by pressing a heat-pressure bonding member from the support side. The pressing conditions for the smoothing treatment may be the same as the heat-pressure bonding conditions for the lamination. The smoothing treatment may be performed using a commercially available laminator. Note that lamination and smoothing treatment may be performed consecutively using the commercially available vacuum laminator.

The support may be removed between steps (I) and (II), or after step (II).

In step (II), the resin composition layer is thermally cured to form a reflective sheet. For example, the thermal curing conditions for the resin composition layer vary depending on the type of resin composition, but the curing temperature is preferably 120°C to 240°C, more preferably 130°C to 220°C, and even more preferably 150°C to 210°C. The curing time is preferably 5 minutes to 120 minutes, more preferably 10 minutes to 100 minutes, and even more preferably 15 minutes to 100 minutes.

Before curing the resin composition, the resin composition may be preheated at a temperature lower than the curing temperature. For example, prior to thermally curing the resin composition, the resin composition may be preheated for 5 minutes or more (preferably 5 minutes to 150 minutes, more preferably 15 minutes to 120 minutes, and even more preferably 15 minutes to 100 minutes) at a temperature of 50°C or higher and lower than 120°C (preferably 60°C or higher and 115°C or lower, and more preferably 70°C or higher and 110°C or lower).

In order to increase the efficiency of extracting light emitted from the light source, the surface of the reflective sheet facing the light source may have a recess in addition to being flat as shown in Figure 1.

In step (III), a light source is placed on the reflective sheet. For example, if the reflective sheet has a recess on its surface, the light source is placed in the recess.

If necessary, the light source may be electrically connected and then sealed to fix it in place.

The present invention will be described in more detail below using examples, but the present invention is not limited to these examples. In the following description, unless otherwise specified, "parts" and "%" mean "parts by mass" and "% by mass", respectively.

Example 1
20 parts of a liquid bisphenol A type epoxy resin ("jER828EL" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 180 g/eq.), 20 parts of a solid fluorine atom-containing epoxy resin ("YX7760" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 245 g/eq.), 35 parts of a phenoxy resin containing a biphenyl skeleton and a cyclohexane skeleton ("YX7200B35" manufactured by Mitsubishi Chemical Corporation, weight average molecular weight 30,000, 20 μm film light transmittance (450 nm) 88%, MEK solution having a solid content of 35 mass %), 0.1 part of an antioxidant ("BHT" manufactured by Wako Pure Chemical Industries, Ltd.), and 0.1 part of an ultraviolet absorber ("Tinuvin P" manufactured by BASF Corporation) were heated and dissolved in 40 parts of MEK with stirring. To this, 50 parts of titanium oxide ("PX3788" manufactured by Sakai Chemical Industry Co., Ltd., average particle size 0.26 μm, treated with phenyltrimethoxysilane ("KBM-103" manufactured by Shin-Etsu Chemical Co., Ltd.), 50 parts of spherical silica ("SO-C2" manufactured by Admatechs Co., Ltd., average particle size 0.5 μm, treated with 3-methacryloxypropyltrimethoxysilane ("KBM-503" manufactured by Shin-Etsu Chemical Co., Ltd.), 20 parts of bisphenol AF ("BIS-AF" manufactured by Central Glass Co., Ltd. (2,2-bis(4-hydroxyphenyl)hexafluoropropane) adjusted to 50% non-volatile content with MEK), and 0.7 parts of phosphorus-based catalyst ("TBP-DA" manufactured by Hokko Chemical Industry Co., Ltd.) were mixed and uniformly dispersed using a high-speed rotating mixer to prepare a resin composition.

Example 2
A resin composition was prepared in the same manner as in Example 1, except that 20 parts of fluorine-containing bisphenol A (a solution of "BisOFP-A" (2,2-bis(3-fluoro-4-hydroxyphenyl)propane) manufactured by Honshu Chemical Industry Co., Ltd.) adjusted to a non-volatile content of 50% with MEK) was used in place of 20 parts of bisphenol AF (a solution of "BIS-AF" (2,2-bis(4-hydroxyphenyl)hexafluoropropane) manufactured by Central Glass Co., Ltd.) adjusted to a non-volatile content of 50% with MEK).

Example 3
A resin composition was prepared in the same manner as in Example 1, except that 20 parts of bisphenol Z (a solution of "BIS-Z" (1,1-bis(4-hydroxyphenyl)cyclohexane) manufactured by Central Glass Co., Ltd.) adjusted to a non-volatile content of 50% with MEK) was used in place of 20 parts of bisphenol AF (a solution of "BIS-AF" (2,2-bis(4-hydroxyphenyl)hexafluoropropane) manufactured by Central Glass Co., Ltd.) adjusted to a non-volatile content of 50% with MEK).

Example 4
A resin composition was prepared in the same manner as in Example 1, except that 20 parts of a fluorene skeleton-containing bisphenol (a solution of "BisOC-FL" (9,9-bis(4-hydroxy-3-methylphenyl)fluorene) manufactured by Honshu Chemical Industry Co., Ltd., adjusted to a non-volatile content of 50% with MEK) was used in place of 20 parts of bisphenol AF (a solution of "BIS-AF" (2,2-bis(4-hydroxyphenyl)hexafluoropropane) manufactured by Central Glass Co., Ltd., adjusted to a non-volatile content of 50% with MEK).

Example 5
A resin composition was prepared in the same manner as in Example 1, except that 20 parts of a hydrogenated liquid epoxy resin ("YX8000" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 205 g/eq.) was used instead of 20 parts of a liquid bisphenol A type epoxy resin ("jER828EL" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 180 g/eq.).

Example 6
A resin composition was prepared in the same manner as in Example 1, except that the amount of titanium oxide ("PX3788" manufactured by Sakai Chemical Industry Co., Ltd., average particle size 0.26 μm, treated with phenyltrimethoxysilane ("KBM-103" manufactured by Shin-Etsu Chemical Co., Ltd.)) was changed from 50 parts to 80 parts, and the amount of spherical silica ("SO-C2" manufactured by Admatechs Co., Ltd., average particle size 0.5 μm, treated with 3-methacryloxypropyltrimethoxysilane ("KBM-503" manufactured by Shin-Etsu Chemical Co., Ltd.)) was changed from 50 parts to 80 parts.

Example 7
A resin composition was prepared in the same manner as in Example 1, except that the amount of titanium oxide ("PX3788" manufactured by Sakai Chemical Industry Co., Ltd., average particle size 0.26 μm, treated with phenyltrimethoxysilane ("KBM-103" manufactured by Shin-Etsu Chemical Co., Ltd.)) used was changed from 50 parts to 100 parts, and 50 parts of spherical silica ("SO-C2" manufactured by Admatechs Co., Ltd., average particle size 0.5 μm, treated with 3-methacryloxypropyltrimethoxysilane ("KBM-503" manufactured by Shin-Etsu Chemical Co., Ltd.)) was not used.

<Comparative Example 1>
A resin composition was prepared in the same manner as in Example 1, except that 20 parts of bisphenol AF (a solution of Central Glass's "BIS-AF" (2,2-bis(4-hydroxyphenyl)hexafluoropropane) adjusted with MEK to a non-volatile content of 50%) was not used, the amount of titanium oxide (average particle size 0.26 μm, Sakai Chemical Industry's "PX3788", treated with phenyltrimethoxysilane (Shin-Etsu Chemical's "KBM-103")) was changed from 50 parts to 44 parts, and the amount of spherical silica (Admatechs'"SO-C2", average particle size 0.5 μm, treated with 3-methacryloxypropyltrimethoxysilane (Shin-Etsu Chemical's "KBM-503")) was changed from 50 parts to 44 parts.

<Comparative Example 2>
A resin composition was prepared in the same manner as in Example 1, except that 20 parts of phthalic anhydride (a solution of New Japan Chemical's "Ricadit TH" adjusted to 50% non-volatile content with MEK) was used instead of 20 parts of bisphenol AF (a solution of Central Glass's "BIS-AF" (2,2-bis(4-hydroxyphenyl)hexafluoropropane) adjusted to 50% non-volatile content with MEK).

<Comparative Example 3>
A resin composition was prepared in the same manner as in Example 1, except that 20 parts of bisphenol F (a solution of "Bis-F" (bis(4-hydroxyphenyl)methane) manufactured by Honshu Chemical Industry Co., Ltd., adjusted to a non-volatile content of 50% with MEK) was used in place of 20 parts of bisphenol AF (a solution of "BIS-AF" (2,2-bis(4-hydroxyphenyl)hexafluoropropane) manufactured by Central Glass Co., Ltd., adjusted to a non-volatile content of 50% with MEK).

<Test Example 1: Measurement of copper foil peel strength (substrate adhesion) before and after HAST (High Speed Accelerated Life Test)>
(1) Preparation of resin sheet A PET film with a release layer ("PET501010" manufactured by Lintec Corporation, thickness 38 μm) was prepared as a support. The resin compositions prepared in the examples and comparative examples were uniformly applied onto the release layer of this support so that the thickness of the resin composition layer after drying was 50 μm. Thereafter, the resin composition was heated at 80 ° C. for 4 minutes to obtain a resin sheet including a resin composition layer having a thickness of 50 μm.

(2) Undercoat treatment of inner layer circuit board A circuit pattern was formed by etching on both sides of a glass cloth-based epoxy resin double-sided copper-clad laminate (copper foil thickness 18 μm, substrate thickness 0.8 mm, Matsushita Electric Works "R5715ES") to produce an inner layer circuit board with an in-plane copper area of 30%. The copper circuit of the obtained inner layer circuit board was roughened with a microetching agent (Mec Co., Ltd. "CZ8100"). Then, it was dried at 190° C. for 30 minutes.

(3) Lamination of resin sheet The resin sheet prepared in (1) above was laminated on both sides of the inner layer circuit board prepared in (2) above using a batch type vacuum pressure laminator (MVLP-500, manufactured by Meiki Co., Ltd.) The lamination was carried out by reducing the pressure for 30 seconds to 13 hPa or less, and then pressing at 120°C for 30 seconds at a pressure of 0.74 MPa to produce an inner layer circuit board laminated with the resin sheet.

(4) Flattening of Resin Sheet Next, the inner layer circuit board laminated with the resin sheet was flattened by heat pressing at atmospheric pressure, 100° C., and a pressure of 0.5 MPa for 60 seconds. Thereafter, the support was peeled off to obtain an “intermediate laminate I” including the resin composition layer, the inner layer board, and the resin composition layer in this order.

(5) Copper foil undercoat treatment On the other hand, the shiny side of "3EC-III" (electrolytic copper foil, 35 μm) manufactured by Mitsui Mining & Smelting Co., Ltd. was immersed in MEC Etch Bond "CZ-8101" manufactured by MEC Corporation to roughen the copper surface (Ra value = 1 μm) and to apply anti-rust treatment (CL8300). This copper foil is called CZ copper foil. It was then heated in an oven at 130°C for 30 minutes.

(6) Lamination of copper foil and formation of insulating layer This roughened copper foil was laminated on both sides of the intermediate laminate I so that the roughened surface of the roughened copper foil was bonded to the resin composition layer of the intermediate laminate I. This lamination was performed under the same conditions as the lamination of the resin sheet to the inner layer substrate described above. As a result, an "intermediate laminate II" was obtained that contained the roughened copper foil, the resin composition layer, the inner layer substrate, the resin composition layer, and the roughened copper foil in this order.

(7) Resin curing This intermediate laminate II was placed in an oven at 100 ° C. and heated for 30 minutes, then transferred to an oven at 180 ° C. and heated for 30 minutes. Next, the intermediate laminate II was removed from the oven under room temperature atmosphere, and then placed in an oven at 200 ° C. and heated for an additional 90 minutes. This resulted in thermal curing of the resin composition layer, and an "evaluation substrate A" was obtained that contained the roughened copper foil, the insulating layer as the cured product of the resin composition layer, the inner layer substrate, the insulating layer as the cured product of the resin composition layer, and the roughened copper foil in this order.

(8) Measurement of copper foil peel strength (substrate adhesion) before HAST (after curing) The evaluation substrate A prepared in (7) above was cut into small pieces of 150 x 30 mm. A cutter was used to make a 10 mm wide and 100 mm long cut in the copper foil part of the small piece, one end of the copper foil was peeled off and held with a gripper (TSE Corporation, Autocom type testing machine, "AC-50C-SL"). Using an Instron universal testing machine, the load (adhesion strength between the roughened copper foil (substrate copper) of the evaluation substrate A and the insulating layer) (kgf/cm) when 35 mm was peeled off in the vertical direction at room temperature (23°C) at a speed of 50 mm/min was measured in accordance with JIS C6481, and the evaluation was performed according to the following criteria.

Evaluation criteria: ⊚: The measurement result of the adhesion to the base is 0.8 kgf/cm or more; ◯: The measurement result of the adhesion to the base is 0.5 kgf/cm or more and less than 0.8 kgf/cm; Δ: The measurement result of the adhesion to the base is 0.3 kgf/cm or more and less than 0.3 kgf/cm; ×: The measurement result of the adhesion to the base is less than 0.3 kgf/cm

(9) Measurement of copper foil peel strength (underlying adhesion) after HAST Meanwhile, HAST was performed on the evaluation substrate A prepared in (7) above, in which the evaluation substrate A was placed in an environment of a temperature of 130° C. and a humidity of 85% RH for 100 hours. After this HAST, the adhesion strength (kgf/cm) between the roughened copper foil (underlying copper) and the insulating layer of the evaluation substrate A was measured by the same method as before the HAST, and evaluated according to the following evaluation criteria.

Evaluation criteria: ⊚: The measurement result of the adhesion to the base is 0.7 kgf/cm or more; ◯: The measurement result of the adhesion to the base is 0.3 kgf/cm or more and less than 0.7 kgf/cm; Δ: The measurement result of the adhesion to the base is 0.2 kgf/cm or more and less than 0.3 kgf/cm; ×: The measurement result of the adhesion to the base is less than 0.2 kgf/cm

<Test Example 2: Measurement of reflectance before and after heat resistance test>
(1) Curing of Resin Sheet The "intermediate laminate I" obtained in Test Example 1(4) above was cured at 180° C. for 60 minutes to obtain an evaluation substrate B.

(2) Measurement of reflectance before heat resistance test (after curing) The evaluation substrate B obtained in (1) above was cut into a piece 50 mm wide and 50 mm long, and the reflectance of light having a wavelength of 460 nm was measured using a multichannel spectrometer (Otsuka Electronics Co., Ltd., MCPD-7700) and evaluated according to the following evaluation criteria.

Evaluation criteria: ⊚: Reflectance is 95% or more; ◯: Reflectance is 90% or more and less than 95%; △: Reflectance is 85% or more and less than 90%; ×: Reflectance is less than 85%

(3) Measurement of reflectance after heat resistance test The evaluation substrate B obtained in (1) above was heated under curing conditions of 125°C for 100 hours, and cut into a piece of 50 mm in width and 50 mm in length. The reflectance of light having a wavelength of 460 nm was measured using a multichannel spectrometer (Otsuka Electronics Co., Ltd., MCPD-7700) and evaluated according to the following evaluation criteria.

Evaluation criteria: ⊚: Reflectance is 90% or more; ◯: Reflectance is 85% or more and less than 90%; △: Reflectance is 80% or more and less than 85%; ×: Reflectance is less than 80%

The above results show that by using a resin composition containing (A) a curing agent, (B) an epoxy resin, and (C) a white inorganic pigment, in which component (A) contains a specific bisphenol curing agent, it is possible to obtain a cured product that has excellent adhesion to the underlying wiring and excellent reflectance.

1 Printed wiring board 2 Substrate 3 Reflective sheet 31 Reflective sheet surface 4 Light source

Claims (27)

A resin composition comprising (A) a curing agent, (B) an epoxy resin, and (C) a white inorganic pigment,
A resin composition, wherein the component (A) contains a curing agent selected from a bisphenol compound having a fluorine atom, a bisphenol compound having an alicyclic structure, and a bisphenol compound having a fluorene skeleton. A resin composition comprising (A) a curing agent, (B) an epoxy resin, and (C) a white inorganic pigment,
The component (A) is represented by the following formula (I):

[wherein R ¹ is the same or different and represents an alkyl group substituted with a fluorine atom, or two R ¹ are bonded together to form a carbon ring which may be substituted with a group selected from an alkyl group and a fluorine atom, R ² is the same or different and represents an alkyl group or a fluorine atom, and a is the same or different and represents an integer of 0 to 4.] In formula (I), R ¹ are the same or different and each represents an alkyl group substituted with a fluorine atom, or two R ¹ The resin composition according to claim 2 , wherein: 4. The resin composition according to claim 1, wherein the component (A) comprises a curing agent selected from a bisphenol compound having a fluorine atom and a bisphenol compound having an alicyclic structure. The resin composition according to any one of claims 1 to 4 , wherein the component (A) comprises a bisphenol compound having a fluorine atom. The resin composition according to claim 5 , wherein the component (A) contains 2,2-bis(4-hydroxyphenyl)hexafluoropropane (bisphenol AF). The resin composition according to any one of claims 1 to 6 , wherein the content of the component (A) is 1% by mass to 20% by mass, based on 100% by mass of non-volatile components in the resin composition. The resin composition according to any one of claims 1 to 7 , wherein the content of the component (C) is 10% by mass to 60% by mass, based on 100% by mass of non-volatile components in the resin composition. The resin composition according to any one of claims 1 to 8, wherein the content of the component (C) is 20 mass% or more, based on 100 mass% of non-volatile components in the resin composition. The resin composition according to any one of claims 1 to 9 , wherein the component (C) is selected from aluminum oxide, titanium oxide, zirconium oxide, magnesium oxide, barium titanate, zinc oxide, cerium oxide, and calcium carbonate. The resin composition according to any one of claims 1 to 10, wherein the content of the component (B) is 40 mass% or less, when the non-volatile components in the resin composition are 100 mass%. The resin composition according to any one of claims 1 to 11 , wherein the content of the component (B) is 10% by mass to 35% by mass, based on 100% by mass of non-volatile components in the resin composition. The resin composition according to any one of claims 1 to 12 , wherein the mass ratio of the component (A) to the component (B) (mass of the component (A)/mass of the component (B)) is 0.1 to 1.0. The resin composition according to any one of claims 1 to 13 , wherein a mass ratio of the component (C) to the component (B) (mass of the component (C)/mass of the component (B)) is 3.0 or less. The resin composition according to any one of claims 1 to 14, wherein the mass ratio of the component (C) to the component (B) (mass of the component (C) / mass of the component (B)) is 0.2 or more. The resin composition according to any one of claims 1 to 15 , further comprising (D) silica. The resin composition according to claim 16, wherein the total content of the components (C) and (D) is 20% by mass or more, based on 100% by mass of non-volatile components in the resin composition. The resin composition according to claim 16 or 17 , wherein the total content of the (C) component and the (D) component is 30% by mass to 80% by mass, where the total amount of non-volatile components in the resin composition is 100% by mass. The resin composition according to any one of claims 16 to 18 , wherein the mass ratio of the component (D) to the component (C) (mass of the component (D) / mass of the component (C)) is 5.0 or less. The resin composition according to any one of claims 16 to 19, wherein the mass ratio of the component (D) to the component (C) (mass of the component (D) / mass of the component (C)) is 0.5 or more. The resin composition according to any one of claims 1 to 20 , wherein the adhesive strength of a cured product of the resin composition to a copper substrate at 23°C is 0.3 kgf/cm or more. The resin composition according to any one of claims 1 to 21 , wherein a cured product of the resin composition has a reflectance of 90% or more for light with a wavelength of 460 nm. The resin composition according to any one of claims 1 to 22 , which is for light reflection. A cured product of the resin composition according to any one of claims 1 to 23 . A resin sheet comprising a support and a resin composition layer formed from the resin composition according to any one of claims 1 to 23 provided on the support. A reflecting sheet comprising a cured product of the resin composition according to any one of claims 1 to 23 . A printed wiring board comprising the reflective sheet according to claim 26 as an interlayer insulating layer or a solder resist layer.

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