WO2012101889A1

WO2012101889A1 - Curable resin composition

Info

Publication number: WO2012101889A1
Application number: PCT/JP2011/075811
Authority: WO
Inventors: 俊之飯島; 清田　達也
Original assignee: 株式会社タムラ製作所
Priority date: 2011-01-27
Filing date: 2011-11-09
Publication date: 2012-08-02
Also published as: JP5685097B2; JP2012153830A

Abstract

Provided is a curable resin composition which has high reflectance with respect to light in the wavelength range from the short wavelength side of the visible light region to the ultraviolet light region and which can be prevented from decrease in the reflectance of the above-described wavelength range even if exposed to the light within the above-described wavelength range. A curable resin composition which is characterized by containing (A) a curable resin and (B) a powder filler in which at least two kinds of inorganic compounds that are selected from the group consisting of zirconium oxide, aluminum oxide, barium carbonate and silicon dioxide are blended.

Description

Curable resin composition

The present invention relates to a curable resin composition having an excellent reflectance, particularly a curable resin composition useful as a solder resist film for a circuit board such as a printed wiring board or a reflective film for a reflective sheet, and the curable resin composition. The present invention relates to a printed wiring board having a cured product and a reflection sheet.

The printed wiring board is used for forming a conductor circuit pattern on a substrate and soldering and mounting an electronic component on the soldering land of the pattern. The circuit portion excluding the soldering land is covered with a solder resist film as a permanent protective film. This prevents solder from adhering to unnecessary parts when soldering electronic components to a printed wiring board, and prevents circuit conductors from being directly exposed to air and being corroded by oxidation or humidity. To do.

The printed wiring board is also used as a substrate for mounting a semiconductor light emitting element such as a light emitting diode element (LED). In this case, a function of improving the reflectance of visible light emitted from the semiconductor light emitting element is provided by blending a white pigment into the solder resist film formed on the mounting surface. However, the white solder resist film has a problem that the light reflectance is lowered due to discoloration caused by high temperature or light irradiation. Therefore, a solder resist material that is difficult to discolor even when exposed to high temperature conditions or light irradiation and that can suppress a decrease in reflectance has been proposed (Patent Document 1).

Further, a printed wiring board having a function of improving the reflectance of visible light emitted from a semiconductor light emitting element using a white resin composition containing a thermosetting resin and a white pigment has been proposed (patent) Reference 2). This printed wiring board has a laminated structure including a base material, a white resin composition layer, and a copper foil.

On the other hand, in recent years, development of a semiconductor light emitting device that emits light in a wavelength band (for example, a wavelength of 300 to 450 nm) from the short wavelength side of the visible light region to the ultraviolet light region is also under development. Accordingly, the solder resist film is required to have a function capable of preventing a decrease in reflectance of light in the wavelength band even when exposed to light in the wavelength band.

Furthermore, solar cells are attracting attention for reducing the environmental load, and in order to improve the power generation efficiency of the solar cells, the wavelength band from the short wavelength side of the visible light region to the ultraviolet light region (for example, the wavelength of 300 to 450 nm). There is a demand for a reflective sheet that can prevent a decrease in the reflectance of light even when exposed to light for a long time.

JP 2010-181693 A JP 2010-100800 A

In view of the above circumstances, the present invention has a high reflectance for light in the wavelength band from the short wavelength side of the visible light region to the ultraviolet light region, and even when exposed to light in the wavelength band, It aims at providing the curable resin composition which can prevent the reflectance fall of light.

An aspect of the present invention contains (A) a curable resin and (B) a powder filler containing at least two inorganic compounds selected from the group consisting of zirconium oxide, aluminum oxide, barium carbonate, and silicon dioxide. It is a curable resin composition characterized by doing. The powder filler containing at least two kinds of inorganic compounds selected from the group consisting of zirconium oxide, aluminum oxide, barium carbonate and silicon dioxide is a white pigment, and by adding this powder filler, the curable resin composition and The cured product becomes white. The curable resin is a thermosetting and / or photocurable resin.

An aspect of the present invention is a curable resin composition in which the powder filler (B) is fired.

An aspect of the present invention is a curable resin composition wherein the powder filler (B) further contains titanium oxide. In this aspect, in addition to at least two inorganic compounds selected from the group consisting of zirconium oxide, aluminum oxide, barium carbonate, and silicon dioxide, the powder filler also contains titanium oxide powder that is a white pigment.

An aspect of the present invention is a curable resin composition characterized in that the (B) powder filler contains 150 to 700 parts by mass with respect to 100 parts by mass of the (A) curable resin.

An aspect of the present invention is a curable resin composition wherein the (A) curable resin is (A-1) a compound having two or more unsaturated groups in one molecule.

An aspect of the present invention is a curable resin composition further comprising (C) a compound having at least one amino group or imino group in one molecule. By further blending the component (C) with the curable resin composition using the component (A-1), efficient thermal curing becomes possible.

An embodiment of the present invention is a curable resin composition further comprising (D) a photopolymerization initiator. When the curable resin is cured with light, that is, when it is exposed to light, a photopolymerization initiator is blended.

An aspect of the present invention is a printed wiring board having a cured film of the curable resin composition. Moreover, the aspect of this invention is a reflective sheet characterized by having the film | membrane obtained by hardening | curing the said curable resin composition.

According to the curable resin composition of the present invention, by containing a powder filler containing at least two inorganic compounds selected from the group consisting of zirconium oxide, aluminum oxide, barium carbonate and silicon dioxide, a visible light region can be obtained. Even when exposed to light in a wavelength band from the short wavelength side to the ultraviolet light region, a cured product capable of suppressing a decrease in reflectance of light in the wavelength band can be obtained. Therefore, the quality stability of the cured product is improved. In addition, the reflectivity of the cured product after being exposed to light in the wavelength band from the short wavelength side of the visible light region to the ultraviolet light region is any one of zirconium oxide, aluminum oxide, barium carbonate, or silicon dioxide. It is possible to maintain the same level of reflectance as the above-described reflectance.

According to the present invention, since the powder filler is fired, the reflectance after being exposed to light on the short wavelength side in the visible light region is not impaired, and after being exposed to light in the ultraviolet region. A decrease in reflectance can be further suppressed.

According to the present invention, by further adding titanium oxide, not only the light on the short wavelength side in the ultraviolet light region and the visible light region, but also the reduction in reflectance after being exposed to the light in the entire visible light region can be suppressed. Can do.

According to the present invention, the powder filler is blended in an amount of 150 to 700 parts by mass with respect to 100 parts by mass of the curable resin, so that the discoloration resistance and the coating property are not impaired, and from the short wavelength side in the visible light region. It is possible to suppress a decrease in reflectivity after exposure to light in the wavelength band over the ultraviolet region.

According to the present invention, the curable resin contains a curable compound having two or more unsaturated groups in one molecule and a compound having at least one amino group or imino group in one molecule. The speed of the polymerization reaction at the time of curing can be increased to the same extent as the speed of the polymerization reaction when the photopolymerization initiator is added and photocured. Thus, since the speed | rate of the polymerization reaction at the time of thermosetting improves, it does not need to harden | cure by light, Therefore, the mixing | blending of a photoinitiator is not required.

According to the present invention, photocuring with a fast polymerization reaction and a short curing time is possible by blending a photopolymerization initiator.

ADVANTAGE OF THE INVENTION According to this invention, the cured film which can prevent the reflectance fall of the light of this wavelength band can be formed on a printed wiring board even if it is exposed to the light of the wavelength band from the short wavelength side of a visible light region to an ultraviolet light region. . In addition, according to the present invention, it is possible to form a reflective film that can prevent a decrease in reflectance of light in the wavelength band even when exposed to light in a wavelength band from the short wavelength side of the visible light region to the ultraviolet light region.

It is a figure explaining the baking conditions of a powder filler.

Next, each component of the curable resin composition of the present invention will be described. The curable resin composition of the present invention is a powder filler comprising (A) a curable resin and (B) at least two inorganic compounds selected from the group consisting of zirconium oxide, aluminum oxide, barium carbonate and silicon dioxide. And each of the above components is as follows.

(A) Curable resin No particular limitation is imposed on either a thermosetting resin that is cured by heating or a photosensitive resin that is cured by ultraviolet rays as long as it is a resin that cures and exhibits electrical insulation.

Examples of the curable resin include (A-1) a compound having two or more unsaturated groups in one molecule.

A compound having two or more unsaturated groups in one molecule includes a compound not containing a carboxyl group having two or more ethylenically unsaturated groups in the molecule, and a carboxyl having two or more ethylenically unsaturated groups in the molecule. Examples thereof include a group-containing compound. Examples of the compound not containing a carboxyl group include a reaction product of an alicyclic epoxy resin and a radically polymerizable unsaturated monocarboxylic acid. The carboxyl group-containing compound is reacted with, for example, a reaction product of an alicyclic epoxy resin and a radical polymerizable unsaturated monocarboxylic acid with a saturated or unsaturated polybasic acid or polybasic acid anhydride. There is something that was obtained.

When the photopolymerization initiator is not included in the curable resin composition, that is, when the curable resin composition is heat-cured without being exposed, from the viewpoint of improving the reactivity of the curable resin composition, as described above. The carboxyl group of the carboxyl group-containing compound obtained by the reaction is further reacted with a glycidyl compound having one or more radically polymerizable unsaturated groups and an epoxy group, and two or more unsaturated groups in one molecule. It is good also as a compound which has. This is because the radically polymerizable unsaturated group is bonded to the side chain of the carboxyl group-containing compound skeleton by the reaction of the glycidyl compound, thereby increasing the degree of unsaturation and improving the reactivity.

The alicyclic epoxy resin is a resin having an alicyclic skeleton, and the skeleton is an epoxy resin formed by a chain of aliphatic cyclic compounds. The epoxy equivalent is not particularly limited, and is, for example, 1000 or less, preferably 100 to 500.

Examples of the alicyclic skeleton epoxy resin include “EHPE-3150” (1,2-epoxy-4- (2-oxiranyl) of 2,2-bis (hydroxymethyl) -1-butanol) manufactured by Daicel Chemical Industries, Ltd. Cyclohexene adduct).

When these epoxy resins are reacted with radically polymerizable unsaturated monocarboxylic acid, the epoxy group is cleaved by the reaction of the epoxy group and the carboxyl group to form a hydroxyl group and an ester bond.

The radically polymerizable unsaturated monocarboxylic acid to be used is not particularly limited, and examples thereof include acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, and at least one of acrylic acid and methacrylic acid is preferable, and acrylic acid is particularly preferable. .

The reaction method between the epoxy resin and the radically polymerizable unsaturated monocarboxylic acid is not particularly limited, and for example, the epoxy resin and acrylic acid can be reacted by heating in an appropriate diluent. Examples of the diluent include ketones such as methyl ethyl ketone and cyclohexanone, aromatic hydrocarbons such as toluene and xylene, alcohols such as methanol, isopropanol and cyclohexanol, alicyclic hydrocarbons such as cyclohexane and methylcyclohexane, Petroleum solvents such as petroleum ether and petroleum naphtha, cellosolves such as cellosolve and butylcellosolve, carbitols such as carbitol and butylcarbitol, ethyl acetate, butyl acetate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butylcarbi Examples include acetates such as tall acetate. Examples of the catalyst include amines such as triethylamine and tributylamine, and phosphorus compounds such as triphenylphosphine and triphenylphosphate.

In the reaction between the epoxy resin and the radically polymerizable unsaturated monocarboxylic acid, 0.7 to 1.2 equivalents of the radically polymerizable unsaturated monocarboxylic acid are reacted per equivalent of the epoxy group of the epoxy resin. If the radically polymerizable unsaturated monocarboxylic acid is less than 0.7 equivalent, gelation occurs during the synthesis reaction in the subsequent step, and the stability of the curable resin decreases. On the other hand, when the amount of the radically polymerizable unsaturated monocarboxylic acid exceeds 1.2 equivalents, a large amount of unreacted carboxylic acid remains, so that various properties (such as water resistance) of the cured product are deteriorated. When at least one of acrylic acid or methacrylic acid is used, it is preferable to react 0.8 to 1.0 equivalent per equivalent of epoxy group of the epoxy resin. The reaction between the epoxy resin and the radically polymerizable unsaturated monocarboxylic acid is preferably carried out in a heated state, and the reaction temperature is particularly preferably from 80 to 140 ° C. If the reaction temperature exceeds 140 ° C., the radically polymerizable unsaturated monocarboxylic acid may undergo thermal polymerization and may be difficult to synthesize. If the reaction temperature is less than 80 ° C., the reaction rate becomes slow and the production efficiency decreases. .

In the reaction of the epoxy resin and the radical polymerizable unsaturated monocarboxylic acid in the diluent, the blending amount of the diluent is preferably 20 to 50% with respect to the total weight of the reaction system. Without isolation of the reaction product of the epoxy resin and the radically polymerizable unsaturated monocarboxylic acid, it can be subjected to the reaction with the following polybasic acids as necessary in the form of a diluent solution.

When a carboxyl group-containing compound having two or more unsaturated groups in one molecule is used, the unsaturated monocarboxylic oxide epoxy resin, which is a reaction product of the epoxy resin and the radical polymerizable unsaturated monocarboxylic acid, is used. The polybasic acid or its anhydride is reacted. The polybasic acid or polybasic acid anhydride reacts with a hydroxyl group generated by the reaction between the epoxy resin and the radically polymerizable unsaturated monocarboxylic acid to give the curable resin a free carboxyl group.

The polybasic acid or its anhydride is not particularly limited, and either saturated or unsaturated can be used. Examples of the polybasic acid include succinic acid, maleic acid, adipic acid, citric acid, phthalic acid, tetrahydrophthalic acid, 3-methyltetrahydrophthalic acid, 4-methyltetrahydrophthalic acid, 3-ethyltetrahydrophthalic acid, 4- Ethyltetrahydrophthalic acid, hexahydrophthalic acid, 3-methylhexahydrophthalic acid, 4-methylhexahydrophthalic acid, 3-ethylhexahydrophthalic acid, 4-ethylhexahydrophthalic acid, methyltetrahydrophthalic acid, methylhexahydro Examples include phthalic acid, endomethylenetetrahydrophthalic acid, methylendomethylenetetrahydrophthalic acid, trimellitic acid, pyromellitic acid, and diglycolic acid. Examples of polybasic acid anhydrides include these anhydrides. These may be used alone or in combination of two or more.

The amount of the polybasic acid or polybasic acid anhydride used is the amino group or imino of the component (C) described later with respect to 1 mol of the hydroxyl group of the reaction product of the epoxy resin and the radical polymerizable unsaturated monocarboxylic acid. The lower limit is 0.3 mol from the viewpoint of preventing the reactivity with the group from being lowered and the solder heat resistance from being lowered, and prevents the deterioration of various properties (for example, water resistance) of the finally obtained cured coating film. From this point, the upper limit is 1.0 mol.

When the polybasic acid is added to the above-described unsaturated monocarboxylic oxide epoxy resin and undergoes the dehydration condensation reaction, it is preferable to continuously take out the water produced during the dehydration condensation reaction from the reaction system, and the reaction is carried out in a heated state. The reaction is preferably carried out at a reaction temperature of 70 to 130 ° C. When the reaction temperature exceeds 130 ° C., synthesis may be difficult due to thermal polymerization of radical-polymerized unsaturated groups of the epoxy resin or unreacted monomers, and the reaction rate is below 70 ° C. This is because the production efficiency is lowered due to the delay.

In order to improve the reactivity of the curable resin composition, the glycidyl compound having one or more radical polymerizable unsaturated groups and an epoxy group to be reacted with the polybasic acid-modified unsaturated monocarboxylic oxide epoxy resin includes, for example, glycidyl. Examples include acrylate, glycidyl methacrylate, allyl glycidyl ether, and pentaerythritol triacrylate monoglycidyl ether. In addition, you may have multiple glycidyl groups in 1 molecule. These compounds may be used alone or in combination of two or more.

The glycidyl compound is added to the solution of the polybasic acid-modified unsaturated monocarboxylic oxide epoxy resin and allowed to react. The glycidyl compound is reacted in an amount of 0.05 to 0.5 mol with respect to 1 mol of the carboxyl group introduced into the polybasic acid-modified unsaturated monocarboxylic oxide epoxy resin, from the viewpoint of electric characteristics such as electric insulation, 0.1 to It is preferable to carry out 0.5 mol reaction. The reaction temperature is preferably 80 to 120 ° C. The acid value of the glycidyl compound-added polybasic acid-modified unsaturated monocarboxylic oxide epoxy resin thus obtained is preferably 45 to 250 mgKOH / g.

(B) Powder filler containing at least two inorganic compounds selected from the group consisting of zirconium oxide, aluminum oxide, barium carbonate and silicon dioxide Zirconium oxide (ZrO ₂ ), aluminum oxide (Al ₂ O ₃ ), barium carbonate Both (BaCO ₃ ) and silicon dioxide (SiO ₂ ) can be used as white pigments. Therefore, the powdery filler of the component (B) is a white pigment mixture in which two or more kinds of white pigments are mixed. The component (B) is a cured product of the curable resin composition, and in order to obtain a predetermined reflectance, in particular, light in a wavelength band from the short wavelength side of the visible light region to the ultraviolet light region (hereinafter referred to as “wavelength 300 to In some cases, it is also referred to as “450 nm light”. By blending two or more of the above white pigments, it is possible to prevent the reflectance from being lowered than when used alone.

The average primary particle size of the powder filler of component (B) is preferably 5.0 μm or less from the viewpoint of coatability, and particularly preferably from 0.1 to 3.0 μm from the viewpoint of light reflectance characteristics and dispersibility. The powder filler preferably contains at least zirconium oxide from the viewpoint of increasing the reflectance of light having a wavelength of 300 to 450 nm, and suppresses a decrease in the reflectance of light even when exposed to light having a wavelength of 300 to 450 nm. It is particularly preferable to blend zirconium oxide, aluminum oxide, barium carbonate and silicon dioxide from the viewpoint of maintaining the reflectance at the beginning of the curing process, and reflectivity of light having a wavelength of 300 to 450 nm and reflection of light having a wavelength of 300 to 450 nm. More preferably, zirconium oxide, aluminum oxide, and barium carbonate are blended from the viewpoint of balance with reduction in rate. The powder filler can be used whether fired or unfired, but is preferably fired from the viewpoint of more stably suppressing a decrease in reflectance of light having a wavelength of 300 to 450 nm.

The blending ratio of two or more inorganic compounds blended in the powder filler can be appropriately selected. For example, in terms of molar ratio, ZrO ₂ is 1, Al ₂ O ₃ is 0.1 to 10, BaCO ₃ is 0.1 to 10, SiO ₂ is 0 to 10, and the short wavelength in the visible light region From the viewpoint of improving the reflectance of light in the wavelength band from the side to the ultraviolet region, ZrO ₂ is 1, Al ₂ O ₃ is 0.5 to 1.5, and BaCO ₃ is 0.5 to 1.5. SiO ₂ is preferably 0 to 1.5, and an equal molar ratio is particularly preferable in that the change in reflectance of light in the wavelength band is surely suppressed before and after ultraviolet irradiation.

The lower limit of the blending amount of the powder filler is 150 from the viewpoint of maintaining the reflectivity at the end of the curing process by suppressing the decrease in reflectivity after irradiation with light having a wavelength of 300 to 450 nm with respect to 100 parts by mass of the curable resin. 200 parts by mass is preferable from the viewpoint of further improving discoloration resistance, and 250 parts by mass is particularly preferable from the viewpoint of reliably improving discoloration resistance. Further, the upper limit is 700 parts by mass from the point of kneadability of the powder filler to the curable resin with respect to 100 parts by mass of the curable resin, and 600 parts by mass is preferable from the viewpoint of further improving the coatability. 500 parts by mass is particularly preferable from the viewpoint of leveling speed after printing.

Further, in the powder filler may be further blended titanium oxide (TiO _2). Titanium oxide is also a pigment for whitening the cured product. By incorporating titanium oxide, not only light with a wavelength of 300 to 450 nm but also light in other visible light regions can be prevented from lowering the reflectance after light irradiation. Examples of titanium oxide include anatase type titanium oxide and rutile type titanium oxide. Either anatase-type titanium oxide or rutile-type titanium oxide can be used, but anatase-type titanium oxide has higher whiteness than rutile-type titanium oxide, but has photocatalytic activity, so that the resin in the curable resin composition May cause discoloration. Since rutile type titanium oxide has almost no photocatalytic activity, it can prevent discoloration of the cured product.

The average particle diameter of the rutile type titanium oxide and anatase type titanium oxide particles is not particularly limited, but is, for example, 0.01 to 1 μm. Further, the surface treating agent for rutile type titanium oxide particles is not particularly limited. Examples of the rutile titanium oxide include “TR-600”, “TR-700”, “TR-750”, “TR-840” manufactured by Fuji Titanium Industry Co., Ltd., and “R-550” manufactured by Ishihara Sangyo Co., Ltd. ”,“ R-580 ”,“ R-630 ”,“ R-820 ”,“ CR-50 ”,“ CR-60 ”,“ CR-90 ”,“ CR-93 ”, manufactured by Titanium Industry Co., Ltd. “KR-270”, “KR-310”, “KR-380”, “JR-1000”, “JR-805”, “JR-806” manufactured by Teika Co., Ltd. can be used.

Either one of rutile titanium oxide and anatase titanium oxide may be used, or a mixture of rutile titanium oxide and anatase titanium oxide may be used. The total amount of rutile-type titanium oxide and anatase-type titanium oxide prevents a decrease in the reflectance of not only light with a wavelength of 300 to 450 nm but also light in the visible light region with respect to 100 parts by mass of the curable resin. From the point of view, it is 10 to 500 parts by weight, and from the viewpoint of coatability, 10 to 400 parts by weight are preferable.

When (A-1) a compound having two or more unsaturated groups in one molecule is used as the curable resin, if necessary, (C) further having at least one amino group or imino group in one molecule You may mix | blend a compound.

In the above aspect, when a compound having one or more amino groups or imino groups in one molecule is blended with a compound having two or more unsaturated groups in one molecule, the polymerization reaction rate during heating of the curable resin composition is increased. This is based on the knowledge that the polymerization reaction rate of the photocurable resin composition is increased to the same level. When a compound having at least one amino group or imino group in one molecule is added, the polymerization reaction rate by heating increases because the amino group or imino group of component (C) becomes carboxyl of component (A-1) by heating. This is considered to react with the group.

Any conventionally known compounds can be used as the compound having at least one amino group or imino group in one molecule. Specific examples include melamine and melamine derivatives. Examples of the melamine derivative include an alkylated melamine containing a functional group such as an imino group, a methylol group, and a methoxymethyl group. Examples of the alkylated melamine include the following general formula (i):

(Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ each independently represents hydrogen, a methylol group, or a methoxymethyl group).

Examples of commercially available melamine derivatives include “Nicarak MW-30HM”, “Nicarak MW-390”, “Nicarac MW-100LM”, “Nicarac MX-750LM” manufactured by Sanwa Chemical Co., Ltd. Can do.

The lower limit of the compounding amount of the compound having one or more amino groups or imino groups in one molecule is 0 from the viewpoint of ensuring the curing speed with respect to 100 parts by mass of the compound having two or more unsaturated groups in one molecule. 1.2 parts by mass from the viewpoint of further improving discoloration resistance, and 1.5 parts by mass is particularly preferable from the viewpoint of further improving the heat resistance of the solder. Moreover, the upper limit of the amount is 10 parts by mass from the viewpoint of water resistance, 5 parts by mass is preferable from the viewpoint of improving electrical characteristics in humidity, and 3 parts by mass is particularly preferable from the viewpoint of high insulation resistance.

(D) Photoinitiator A photoinitiator is mix | blended when photocuring a curable resin. The photopolymerization initiator is not particularly limited as long as it is generally used. For example, an oxime initiator, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether Acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl Phenylketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, ben Zophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tertiarybutylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4 diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, P-dimethylaminobenzoic acid ethyl ester, and the like. These may be used alone or in combination of two or more. The blending amount of the photopolymerization initiator is 1 to 40 parts by mass, preferably 5 to 30 parts by mass with respect to 100 parts by mass of the curable resin.

In addition to the components (A) to (D) described above, the curable resin composition of the present invention may contain the following components as necessary.

Diluent The diluent is, for example, a polymerizable monomer that is a reactive diluent, and is used to obtain a cured product having sufficient acid resistance, heat resistance, alkali resistance, etc., by sufficiently curing the curable resin. Examples of the polymerizable monomer include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, neo Pentyl glycol adipate di (meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone-modified dicyclopentenyl di (meth) acrylate, ethylene oxide-modified phosphate di (meth) Acrylate, allylated cyclohexyl di (meth) acrylate, isocyanurate di (meth) acrylate, trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate Propionate modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris (acryloxyethyl) isocyanurate, propionic acid modified dipentaerythritol Examples include penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and caprolactone-modified dipentaerythritol hexa (meth) acrylate. These may be used alone or in combination of two or more.

The amount of the reactive diluent described above is 2.0 to 100 parts by mass, preferably 10 to 60 parts by mass, and particularly preferably 20 to 50 parts by mass with respect to 100 parts by mass of the curable resin.

Epoxy compound The epoxy compound is for obtaining a cured coating film having sufficient mechanical strength by increasing the crosslinking density of the cured product. Examples of the epoxy compound include an epoxy resin. Examples of the epoxy resin include bisphenol A type epoxy resin, novolak type epoxy resin (phenol novolak type epoxy resin, o-cresol novolak type epoxy resin, p-tert-butylphenol novolak type, etc.), bisphenol F and bisphenol S with epichlorohydrin. Bisphenol F type and bisphenol S type epoxy resins obtained by reaction, alicyclic epoxy resins having cyclohexene oxide groups, tricyclodecane oxide groups, cyclopentene oxide groups, and the like, tris (2,3-epoxypropyl) isocyanurate , Triglycidyl isocyanurate having a triazine ring such as triglycidyl tris (2-hydroxyethyl) isocyanurate, dicyclopentadiene type epoxy resin, Adama It can be exemplified Tan type epoxy resin or the like. These compounds may be used alone or in combination of two or more. The compounding amount of the epoxy compound is 1 to 75 parts by mass with respect to 100 parts by mass of the curable resin from the viewpoint of obtaining a sufficient coating film after curing and improving the solder heat resistance. From the viewpoint of balance of properties, 10 to 30 parts by mass is preferable.

Solvent A non-reactive organic solvent may be used to adjust the viscosity and drying properties of the curable resin composition. Examples of the organic solvent include ketones such as methyl ethyl ketone and cyclohexanone, aromatic hydrocarbons such as toluene and xylene, alcohols such as methanol, isopropanol and cyclohexanol, alicyclic hydrocarbons such as cyclohexane and methylcyclohexane, Petroleum solvents such as petroleum ether and petroleum naphtha, cellosolves such as cellosolve and butylcellosolve, carbitols such as carbitol and butylcarbitol, ethyl acetate, butyl acetate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butylcarbi Examples include acetates such as tall acetate and diethylene glycol monoethyl ether acetate. When the organic solvent is used, the blending amount is 10 to 500 parts by weight, preferably 20 to 100 parts by weight, based on 100 parts by weight of the curable resin.

As the antifoaming agent, known ones can be used, and examples thereof include silicone-based, hydrocarbon-based and acrylic-based agents.

Examples of additives include dispersants such as coupling agents such as silane, titanate, and alumina, boron trifluoride-amine complex, dicyandiamide (DICY) and its derivatives, organic acid hydrazide, and diaminomaleonitrile (DAMN). And its derivatives, and latent curing agents such as guanamine and its derivatives, metal salts of acetylacetone such as acetylacetonate Zn and acetylacetonateCr, enamine, tin octylate, quaternary sulfonium salt, triphenylphosphine, imidazole, Examples include imidazolium salts and thermosetting accelerators such as triethanolamine borate.

Further, an extender pigment may be blended in order to increase the physical strength of the coating film of the curable resin composition. Examples of extender pigments include aluminum hydroxide, talc, and mica.

The method for producing the curable resin composition of the present invention is not limited to a specific method, for example, after blending the above-mentioned predetermined components in a predetermined ratio, at room temperature, kneading means such as a three roll, ball mill, sand mill, Alternatively, it can be produced by kneading or mixing with a stirring means such as a super mixer or a planetary mixer. Further, prior to the kneading or mixing, if necessary, preliminary kneading or premixing may be performed.

Hereinafter, a method for using the curable resin composition of the present invention will be described. First, the case where the curable resin composition of the present invention is applied to a printed wiring board and used as a solder resist film will be described as an example.

When photocuring a curable resin composition containing a photopolymerization initiator, the curable resin composition of the present invention produced as described above has a circuit pattern formed by etching a copper foil, for example. On a printed wiring board, it is applied to a desired thickness, for example, 5 to 100 μm, using a screen printing method, a roll coater method, a bar coater method, a spray coater method, a curtain flow coater method, a gravure coater method or the like. Next, in order to volatilize the solvent in the curable resin composition, preliminary drying is performed by heating at a temperature of about 60 to 80 ° C. for about 15 to 60 minutes to form a tack-free coating film. Then, the negative film which has the pattern which made translucent except the land of the said circuit pattern was stuck on the apply | coated curable resin composition, and an ultraviolet-ray is irradiated from it. Then, the coating film is developed by removing the non-exposed areas corresponding to the lands with a dilute alkaline aqueous solution. As the developing method, a spray method, a shower method, or the like is used. As the dilute alkaline aqueous solution used, a 0.5 to 5% sodium carbonate aqueous solution is generally used, but other alkalis can also be used. Next, the coating film is thermally cured by performing a post-cure for 20 to 80 minutes using a hot-air circulating dryer at 130 to 170 ° C. to form a solder resist film of the desired curable resin composition on the printed wiring board. Can be formed.

When thermosetting a curable resin composition not containing a photopolymerization initiator, the curable resin composition of the present invention produced as described above has, for example, a circuit pattern formed by etching a copper foil. On the printed wiring board, screen printing method, spray coater method, honmelt coater method, bar coater method, applicator method, blade coater method, knife coater method, air knife coater method, curtain flow coater method, roll coater method, gravure coater method, Using an offset printing method, a dip coater method, brush coating, etc., it is applied to a desired thickness, for example, 5 to 100 μm. After coating, in order to volatilize the solvent in the curable resin composition, preliminary drying is performed by heating at a temperature of about 60 to 80 ° C. for about 15 to 60 minutes to form a tack-free coating film. Thereafter, the coating film is thermally cured by performing a post-cure for 20 to 80 minutes with a hot air circulation dryer or the like at 130 to 170 ° C., and a solder resist film of the desired curable resin composition on the printed wiring board. Can be formed.

An electronic circuit unit is formed by soldering an electronic component to the printed wiring board covered with the cured coating film thus obtained by a jet soldering method, a reflow soldering method, or the like.

Next, the case where the curable resin composition described above is applied to the surface of a sheet-like base film and used as a reflective film will be described as an example. After the surface of the sheet-like base film is washed by, for example, acid treatment, the curable resin composition produced as described above is applied to the washed surface by a predetermined coating means with a desired thickness, for example, 5 to 100 μm. Apply to thickness. After coating, pre-drying is performed at a temperature of about 60 to 80 ° C. for about 15 to 60 minutes to form a tack-free coating film. Next, by performing post-cure at a temperature of about 130 to 170 ° C. for 10 to 80 minutes, a target white cured coating film, that is, a reflective coating film can be formed on the surface of the sheet-like base film to produce a reflective sheet.

The material of the sheet-like base film is not particularly limited. For example, polyimide, polyethylene terephthalate (PET), polyvinyl fluoride (PVF), fluorinated ethylene / propylene copolymer (FEP), polytetrafluoroethylene (PTFE), aramid , Polyamide / imide, epoxy, polyetherimide, polysulfone, polyethylene naphthalate (PEN), liquid crystal polymer (LCP), and the like.

Also, the coating means is not particularly limited, and for example, screen printing method, spray coater method, honmelt coater method, bar coater method, applicator method, blade coater method, knife coater method, air knife coater method, curtain flow coater method , Roll coater method, gravure coater method, offset printing method, dip coater method, brush coating and the like.

Hereinafter, an example of how to use the reflection sheet will be described. For example, the reflection sheet can be used as a back sheet by being disposed on the back surface side of the solar cell module, that is, on the surface opposite to the surface receiving solar radiation. When the reflective sheet is used as a back sheet, the sunlight transmitted through the solar cell module without being received by the power generation element of the solar cell module is reflected by the reflective film of the reflective sheet, and again from the back side of the solar cell module. Since it is returned to the inside of the module, the power generation efficiency of the solar cell module is improved. In addition, the installation method of the reflective sheet to a solar cell module back surface includes the method of sticking directly on a solar cell module back surface using an adhesive agent or an adhesive tape, for example.

When the reflective sheet is used for the back sheet of the solar cell module, for example, a polyethylene terephthalate film having a thickness of 40 μm is used as the base film. Further, the curable resin composition is applied so that the film thickness after curing becomes a predetermined value (for example, 20 to 23 μm). Furthermore, it is preferable that the coating part of the curable resin composition is performed on the entire surface or substantially the entire surface of the base film facing the back surface of the solar cell module.

Next, examples of the present invention will be described, but the present invention is not limited to these examples as long as it does not exceed the gist thereof.

Examples 1-7, Comparative Examples 1-5
Ingredients shown in Table 1 below were blended at the blending ratios shown in Table 1 below, premixed with a stirrer, mixed and dispersed at room temperature using three rolls, Examples 1 to 7 and Comparative Examples 1 to 5 curable resin compositions were prepared. In addition, the numerical value of the mixture ratio in Table 1 shows a mass part.

Details of each component in Table 1 are as follows.
(A) Curable resin / Cyclomer P (ACA) Z-300: A carboxyl group-containing resin using a resin having an acrylic copolymer structure manufactured by Daicel Chemical Industries, Ltd.
(B) Powder filler The composition of powder fillers A to D, which is a mixture of pigments used in the examples, and zirconium oxide (ZrO ₂ ), titanium oxide (TIO ₂ ), and aluminum oxide (Al ₂ O ₃ ) used in the comparative examples. The details of barium carbonate (BaCO ₃ ) are shown in Table 2 below.

The powder filler A is different from the powder filler C in that it is fired at 1300 ° C. under the firing conditions shown in FIG. 1 and in that a binder resin, a plasticizer, a lubricant and a solvent are blended. However, the binder resin, plasticizer, lubricant and solvent are all formulated for the purpose of further improving the moldability of the powder filler A upon firing. The binder resin, plasticizer, lubricant and solvent are volatilized by firing. Therefore, it does not affect the following evaluation results of the examples. The same applies to the relationship between the powder filler B and the powder filler D.

(D) Photopolymerization initiator Irgacure 184: 1-hydroxy-cyclohexyl-phenyl-ketone manufactured by Ciba Specialty Chemicals Co., Ltd.
Other components / diluent: M-408: Ditrimethylolpropane tetraacrylate manufactured by Toa Gosei Co., Ltd.
Epoxy compound; EPICRON 850: Dainippon Ink & Chemicals, Inc., bisphenol A type epoxy resin.
Antifoaming agent: KS-66: Silicone antifoaming agent manufactured by Shin-Etsu Chemical Co., Ltd.
Among the additives, DICY-7 is a curing accelerator manufactured by Japan Epoxy Resin Co., Ltd., R-974 is a thixotropic agent manufactured by Nippon Aerosil Co., Ltd., and Sumilizer GA-80 is manufactured by Sumitomo Chemical Co., Ltd. Of 3,9-bis [2- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl] -2,4,8,10-tetraoxa Spiro [5,5] undecane, an antioxidant.

Test piece preparation process 1
The surface of a printed wiring board having a circuit pattern formed by etching a copper foil (manufactured by Panasonic Electric Works Co., Ltd., FR-4 substrate, plate thickness 1.6 mmt, conductor thickness 35 μm) was acid-treated with a 3% sulfuric acid aqueous solution. Thereafter, the curable resin compositions of Examples 1 to 7 and Comparative Examples 1 to 5 were respectively applied by screen printing. Thereafter, preliminary drying was performed in a BOX furnace at 70 ° C. for 20 minutes (25 minutes in the BOX furnace). For Example 3 only, after preliminary drying, the coating film was exposed to 400 mJ / cm ^{2 with} an exposure apparatus (HMW-680GW manufactured by Oak Co.) for 1 minute, and then 0 ° C. was added with 30% 1% aqueous sodium carbonate solution. .Developed by spraying at 1 MPa for 60 seconds. For Example 3, after development, and for other Examples and Comparative Examples, after preliminary drying, post-curing was performed at 150 ° C. for 60 minutes (70 minutes in the BOX furnace) and cured on the printed wiring board. A cured coating film of the resin composition was formed to prepare a test piece. The thickness of the cured coating film was 20 to 23 μm.

Evaluation item (1) Reflectivity (%)
In the measurement of reflectance, the prepared curable resin composition was applied to the surface of a slide glass (50 × 50 × 1 mm) to a thickness of 100 μm by a screen printing method, and then cured by heating at 150 ° C. for 1 hour. It was a piece. Next, the cured coating film of this test piece was post-cured with a UV-visible spectrophotometer (UV-3310 manufactured by Hitachi High-Tech) with a scan width of 200 to 800 nm, a scan speed of 600 nm / min, and a slit width of 5 mm ( Hereinafter, the reflectance of “the initial stage of curing” was measured. The standard white board was Al ₂ O ₃ . After measuring the reflectivity at the initial stage of curing, UV light with a wavelength of 300 to 450 nm is applied to the cured coating film of the test piece using an exposure apparatus (Oak Seisakusho, HMW-680GW, lamp SMX-7000H) until the accumulated light quantity reaches 800 J / cm ² Were irradiated. Then, the reflectance after ultraviolet irradiation was measured by the same method as the reflectance at the initial stage of curing. Further, the reflectance maintenance rate (%) was calculated from reflectance after ultraviolet irradiation / reflectance at the initial stage of curing × 100.

(2) Discoloration resistance About the test piece created in the test piece preparation step 1, after heating at 170 ° C. for 100 hours, the color tone of the cured coating film was visually observed and evaluated according to the following criteria.
○: No discoloration, Δ: Some discoloration is observed, ×: Yellow discoloration (3) Insulation resistance IPC-TM-840B IPC-TM840B B- Using 25 test coupon comb electrodes, 85 ° C., 85% R.D. H. The insulation resistance after the humidification treatment for 200 hours was measured by applying DC 50V.
(4) Solder heat resistance After the test piece prepared in the test piece preparation step 1 is immersed in a solder bath at 260 ° C for 30 seconds in accordance with the test method of JIS C-6481, a peeling test using a cellophane tape is defined as one cycle. The coating state after repeating 1 to 3 times was visually observed and evaluated according to the following criteria.
A: No change is observed in the coating film even after 3 cycles are repeated. O: Only a slight change is observed in the coating film after the 3 cycles. Δ: A change is observed in the coating film after the 2 cycles. Peeling is observed in the coating film after one cycle.
(5) Viscosity Using a Brookfield HBT type viscometer, the viscosity at 25 ° C. of the curable resin composition before coating was measured.
(6) Coating property The state of the coated film after screen printing was visually observed and evaluated according to the following criteria.
○: Smooth coating surface and no bubbles, Δ: Slight unevenness on the coating surface, generation of bubbles is observed, ×: Many unevenness on the coating surface and not smooth.

Evaluation results are shown in Table 3 below.

In Table 3, “−” in the reflectance means that the reflectance is as low as 5% or less and measurement is impossible because noise is generated.

From Table 3, powder filler A or C containing zirconium oxide (ZrO ₂ ), aluminum oxide (Al ₂ O ₃ ), barium carbonate (BaCO ₃ ), and silicon dioxide (SiO ₂ ), or zirconium oxide (ZrO ₂ ) Examples 1 to 7 using powder filler B or D containing aluminum oxide (Al ₂ O ₃ ) and barium carbonate (BaCO ₃ ) are comparative examples 1 using aluminum oxide (ZrO ₂ ), aluminum oxide (Al Compared to Comparative Example 4 using ₂ O ₃ ) and Comparative Example 5 using barium carbonate (BaCO ₃ ), the maintenance ratio is high, that is, the decrease in reflectance of light having a wavelength of 300 to 450 nm after ultraviolet irradiation is suppressed. It was. Therefore, Examples 1 to 7 are excellent in quality stability because the decrease in reflectance can be suppressed even when exposed to light in the wavelength band from the short wavelength side of the visible light region to the ultraviolet light region. From Comparative Examples 2 and 3, even when titanium oxide (TiO ₂ ) was blended, a predetermined reflectance for ultraviolet light could not be obtained.

From the comparison between Examples 1 and 2 and Examples 4 and 5, when the powder filler was baked, the maintenance rate in light having a wavelength of 300 to 350 nm was particularly improved. From the comparison of Examples 1 to 5, 7 and Example 6, when the powder filler was mixed in an amount of more than 159.7 parts by mass with respect to 100 parts by mass of the curable resin, not only the maintenance rate but also the color fastness was further improved. From the comparison between Examples 1 to 6 and Example 7, by adding less than 689.8 parts by mass of the powder filler to 100 parts by mass of the curable resin, the increase in the viscosity of the curable resin composition can be suppressed and coating can be performed. Also improved. From the comparison between Example 1 and Example 2, when a powder filler containing zirconium oxide (ZrO ₂ ), aluminum oxide (Al ₂ O ₃ ), and barium carbonate (BaCO ₃ ) is used for the fired product, the initial stage of curing and ultraviolet rays are used. The reflectivity and maintenance rate after irradiation improved with better balance. Further, even when a photopolymerization initiator is blended and exposed to light (Example 3), or when a photopolymerization initiator is not blended and heat-cured (Examples 1, 2, 4 to 7), an equivalent reflectance is obtained. A retention rate was obtained.

The curable resin composition of the present invention provides a cured product that can prevent a decrease in reflectance of light in the wavelength band even when exposed to light in the wavelength band from the short wavelength side of the visible light region to the ultraviolet light region. Therefore, for example, the utility value is high as the solder resist film of the printed wiring board, in particular, a printed wiring board on which a semiconductor light emitting element that emits light in the above-mentioned wavelength band is mounted. Moreover, the utility value is high also as a reflection sheet, for example, a solar cell backsheet.

Claims

(A) A curable resin and (B) a powder filler containing at least two inorganic compounds selected from the group consisting of zirconium oxide, aluminum oxide, barium carbonate, and silicon dioxide. Curable resin composition.
2. The curable resin composition according to claim 1, wherein the (B) powder filler is fired.
The curable resin composition according to claim 1 or 2, wherein the (B) powder filler further contains titanium oxide.
The curable resin according to any one of claims 1 to 3, wherein the (B) powder filler contains 150 to 700 parts by mass with respect to 100 parts by mass of the (A) curable resin. Composition.
The curable resin composition according to claim 1, wherein the (A) curable resin is (A-1) a compound having two or more unsaturated groups in one molecule.
The curable resin composition according to claim 5, further comprising (C) a compound having at least one amino group or imino group in one molecule.
Furthermore, (D) a photoinitiator is contained, The curable resin composition of any one of the Claims 1 thru | or 6 characterized by the above-mentioned.
A printed wiring board comprising a cured film of the curable resin composition according to any one of claims 1 to 7.
A reflective sheet comprising a film obtained by curing the curable resin composition according to any one of claims 1 to 7.