JP2012041430A - White curable resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a white curable resin composition that can prevent cracks from occurring on a cured film due to punching process, hole-forming process or the like.SOLUTION: The white curable resin composition comprises: an active energy ray-curable resin (A) having at least two ethylenically unsaturated bonds in one molecule; a photoinitiator (B); a diluent (C); titanium oxide (D); an epoxy thermosetting compound (E); and an inorganic compound (F) having an aspect ratio of 5 or larger.

Description

  The present invention relates to a white curable resin composition having crack resistance suitable for various resists such as a solder resist of a printed wiring board and a reflective film of a reflection sheet, and a printed wiring board coated with a cured product obtained by curing the same. The present invention relates to a reflection sheet.

  Conventionally, the curable resin composition may be used as, for example, a solder resist film of a printed wiring board. The printed wiring board may be used as a mounting substrate for a light emitting diode element (LED) or the like. In this case, the solder resist film formed on the mounting surface has a function of improving the reflectance of light from the light source. It has been demanded. And in order to raise the reflectance of the cured film of curable resin composition, mix | blending inorganic white pigments, such as a titanium oxide, is known.

  However, when a large amount of an inorganic white pigment such as titanium oxide is added to increase the reflectance of the cured film of the curable resin composition, there is a problem that the crack resistance of the cured film is not sufficient. Accordingly, cracks and peeling occur in the solder resist film during the punching process and the hole punching process of the printed wiring board.

  Therefore, in order to impart large mechanical properties to the cured film, Patent Document 1 discloses that the inorganic filler is 10 to 1200 parts by mass, the elastic modulus (MPa) is 1 to 2000, and the average particle diameter is 100 parts by mass of the curable resin. A curable resin composition containing 0.01 to 10 μm of an organic filler of 1 to 100 parts by mass and containing an inorganic filler and an organic filler in a weight ratio of 1 to 41 is disclosed.

  However, even with the curable resin composition of Patent Document 1, although the reduction in pencil hardness and adhesion can be suppressed, the cured film has insufficient crack resistance, and the cured film still has cracks and delamination during punching and drilling. There was a problem that it would occur.

  Moreover, when using a reflective sheet as a back sheet | seat of a solar cell, it is necessary to attach a reflective sheet to a solar cell, or to process into the shape of a solar cell. Accordingly, the reflective film of the reflective sheet is also required to have crack resistance enough to withstand punching and drilling.

JP 2009-102623 A

  In view of the above circumstances, an object of the present invention is to provide a white curable resin composition capable of preventing and suppressing cracks generated in a cured film by punching or drilling.

  Aspects of the present invention include (A) an active energy ray-curable resin having at least two ethylenically unsaturated bonds in one molecule, (B) a photopolymerization initiator, (C) a diluent, and (D) titanium oxide. And (E) an epoxy-based thermosetting compound, and (F) an inorganic compound having an aspect ratio of 5 or more.

  In an embodiment of the present invention, (F) the inorganic compound having an aspect ratio of 5 or more is added to (A) 100 parts by mass of the active energy ray-curable resin having at least two ethylenically unsaturated bonds in one molecule. The white curable resin composition is characterized by containing 5 to 80 parts by mass.

  An aspect of the present invention is characterized in that the (F) inorganic compound having an aspect ratio of 5 or more is at least one whisker-like compound selected from the group consisting of potassium titanate, magnesium sulfate, silicon carbide, and calcium carbonate. The white curable resin composition.

  Furthermore, the following general formula (I)

(Wherein R ¹ and R ² each independently represents a methyl group, a hydrogen atom or a t-butyl group) (G) a phenolic compound containing the phenolic compound It is a resin composition.

  In an embodiment of the present invention, (H) urethane acrylate is further added in an amount of 10 to 30 with respect to 100 parts by mass of (A) active energy ray-curable resin having at least two ethylenically unsaturated bonds in one molecule. It is a white curable resin composition characterized by containing a mass part.

  The aspect of this invention is a printed wiring board which has the cured film of the said white curable resin composition.

  The aspect of this invention is a reflective sheet which has a reflective film formed with the said white curable resin composition.

  According to the aspect of the present invention, a cured product having excellent punch crack resistance can be formed by adding an inorganic compound having an aspect ratio of 5 or more to the white curable resin composition, so that a crack caused by punching or drilling or the like can be formed. Can be prevented and suppressed. According to the aspect of the present invention, the inorganic compound having an aspect ratio of 5 or more is 5 to 80 masses per 100 mass parts of the active energy ray-curable resin having at least two ethylenically unsaturated bonds in one molecule. By containing a part, a cured product having excellent cupping resistance in addition to punching crack resistance can be formed. According to the aspect of the present invention, it is possible to further suppress a decrease in reflectivity after heating by containing the phenol compound of the general formula (i). According to the aspect of the present invention, by containing 10 to 30 parts by mass of urethane acrylate with respect to 100 parts by mass of active energy ray-curable resin having at least two ethylenically unsaturated bonds in one molecule, The flexibility of the cured product is improved and the cupping resistance is further improved.

  According to the aspect of the present invention, a printed wiring board having a cured film excellent in punch crack resistance and cupping resistance can be obtained. Moreover, according to the aspect of the present invention, it is possible to obtain a reflective sheet having a reflective coating excellent in punch crack resistance and cupping resistance.

  Next, the white curable resin composition of the present invention will be described. The white curable resin composition of the present invention includes (A) an active energy ray-curable resin having at least two ethylenically unsaturated bonds in one molecule, (B) a photopolymerization initiator, (C) a diluent, It contains (D) titanium oxide, (E) an epoxy thermosetting compound, and (F) an inorganic compound having an aspect ratio of 5 or more, and each of the above components is as follows.

(A) Active energy ray-curable resin having at least two ethylenically unsaturated bonds in one molecule For an active energy ray-curable resin having at least two ethylenically unsaturated bonds in one molecule, for example, A radically polymerizable unsaturated monocarboxylic acid such as acrylic acid or methacrylic acid is reacted with at least a part of the epoxy group of a polyfunctional epoxy resin having two or more epoxy groups in the molecule to obtain an epoxy (meth) acrylate, A polybasic acid-modified epoxy (meth) acrylate obtained by reacting the produced hydroxyl group with a polybasic acid or an anhydride thereof can be mentioned.

  Any polyfunctional epoxy resin can be used as long as it is a bifunctional or higher functional epoxy resin, and there is no particular limitation on the epoxy equivalent, but, for example, one having 1000 or less, preferably 100 to 500 is used. Examples of the polyfunctional epoxy resin include biphenyl type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, rubber modified epoxy resin such as silicone modified epoxy resin, ε-caprolactone modified epoxy resin, bisphenol A type, bisphenol. Phenol type novolak type epoxy resin such as F type, bisphenol AD type, cresol novolak type epoxy resin such as о-cresol novolak type, bisphenol A novolak type epoxy resin, cyclic aliphatic polyfunctional epoxy resin, glycidyl ester type polyfunctional epoxy resin, Glycidylamine type polyfunctional epoxy resin, heterocyclic polyfunctional epoxy resin, bisphenol modified novolac type epoxy resin, polyfunctional modified novolak type epoxy resin, phenols and phenolic hydroxyl group Examples thereof include condensate type epoxy resins with aromatic aldehydes. Moreover, what introduce | transduced halogen atoms, such as Br and Cl, to these resin can also be used. Of these, rubber-modified epoxy resins such as silicone-modified epoxy resins are preferred from the viewpoint of the flexibility of the coating film. These epoxy resins may be used alone or in combination of two or more.

  The above-mentioned epoxy resin is reacted with a radically polymerizable unsaturated monocarboxylic acid. The epoxy group is cleaved by the reaction between 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 the like. At least one of acrylic acid and methacrylic acid (hereinafter referred to as (meth)). Acrylic acid is sometimes preferred.) Acrylic acid is particularly preferred. What reacted (meth) acrylic acid is epoxy (meth) acrylate.

  The reaction method of an epoxy resin and radically polymerizable unsaturated monocarboxylic acid is not specifically limited, For example, it can react by heating an epoxy resin and acrylic acid in a suitable 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, and 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, butyl Examples include acetates such as carbitol acetate. Examples of the catalyst include amines such as triethylamine and tributylamine, and phosphorus compounds such as triphenylphosphine and triphenylphosphate. Moreover, although heating temperature can be set suitably, the lower limit is preferable from the point which prevents that reaction rate becomes slow. The upper limit of the reaction rate is preferably 140 ° C. from the viewpoint of preventing thermal polymerization of the radical polymerizable unsaturated monocarboxylic acid.

  In the reaction between the epoxy resin and the radically polymerizable unsaturated monocarboxylic acid, it is preferable to react 0.7 to 1.2 equivalents of the radically polymerizable unsaturated monocarboxylic acid per 1 equivalent of the epoxy group of the epoxy resin. When at least one of acrylic acid or methacrylic acid is used as the radically polymerizable unsaturated monocarboxylic acid, 0.8 to 1.0 equivalent of the radically polymerizable unsaturated monocarboxylic acid is reacted per 1 equivalent of epoxy group of the epoxy resin. It is particularly preferred that When the radically polymerizable unsaturated monocarboxylic acid is less than 0.7 equivalent, gelation occurs during the synthesis reaction in the subsequent step, or the stability of the resin decreases. Further, when the radical polymerizable unsaturated monocarboxylic acid exceeds 1.2 equivalents, a large amount of unreacted carboxylic acid remains, and various properties (for example, water resistance) of the cured product are deteriorated.

  A polybasic acid or an anhydride thereof is reacted with the unsaturated monocarboxylic oxide epoxy resin which is a reaction product of the epoxy resin and the radically polymerizable unsaturated monocarboxylic acid. 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 resin a free carboxyl group. The polybasic acid to be used or its anhydride is not particularly limited, and either saturated or unsaturated can be used. Polybasic acids include, for example, 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 compounds may be used alone or in combination of two or more.

  The lower limit of the amount of polybasic acid or polybasic acid anhydride used prevents the deterioration of dilute alkali developability with respect to 1 mol of hydroxyl group in the reaction product of epoxy resin and radically polymerizable unsaturated monocarboxylic acid. The amount is 0.3 mol from the viewpoint of performing, and is preferably 0.4 mol, particularly preferably 0.6 mol from the viewpoint of increasing the sensitivity during exposure. Moreover, the upper limit of the usage-amount of a polybasic acid or a polybasic acid anhydride is preferable 1.0 mol from the point which prevents the various characteristics (for example, water resistance etc.) of a cured coating film.

  The polybasic acid is preferably added to the unsaturated monocarboxylic oxide epoxy resin and subjected to a dehydration condensation reaction. The water produced during the reaction is preferably removed continuously from the reaction system, but the reaction is preferably carried out in a heated state. The reaction temperature is preferably 70 to 130 ° C. When the reaction temperature exceeds 130 ° C., those bonded to an epoxy resin and radically polymerizable unsaturated groups of unreacted monomers may easily cause thermal polymerization, making synthesis difficult. The speed is slow, which may be undesirable in actual manufacturing.

  The acid value of the polybasic acid-modified unsaturated monocarboxylic acid epoxy resin, which is a reaction product of the polybasic acid or polybasic acid anhydride and the unsaturated monocarboxylic acid epoxy resin, is preferably 60 to 300 mgKOH / g. The acid value of the reaction product can be adjusted by the amount of the polybasic acid to be reacted.

  In the present invention, the polybasic acid-modified unsaturated monocarboxylic oxide epoxy resin can also be used as an active energy ray-curable resin having at least two ethylenically unsaturated bonds in one molecule. By reacting the carboxyl group of the saturated monocarboxylic oxide epoxy resin with one or more radically polymerizable unsaturated groups and a glycidyl compound having an epoxy group, radically polymerizable unsaturated groups are further introduced to further improve photosensitivity. It is good also as an active energy ray-curable resin which has at least 2 ethylenically unsaturated bond in 1 molecule improved.

  In the active energy ray-curable resin having at least two ethylenically unsaturated bonds in one molecule with improved photosensitivity, the radically polymerizable unsaturated group is reacted with the precursor photosensitivity by the reaction of the last glycidyl compound. Since it bonds to the side chain of the polymer skeleton of the photosensitive resin, it has high photopolymerization reactivity and can have excellent photosensitivity. Examples of the compound having one or more radically polymerizable unsaturated groups and an epoxy group include glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, pentaerythritol triacrylate monoglycidyl ether, and the like. 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 and reacted with the polybasic acid-modified unsaturated monocarboxylic oxide epoxy resin solution. For example, 0.05 to 0.5 mol per mol of the carboxyl group introduced into the resin. React at a rate of From the viewpoint of electrical characteristics such as photosensitivity, thermal management width and electrical insulation of a white curable resin composition containing an active energy ray-curable resin having at least two ethylenically unsaturated bonds in one molecule, 0 It is preferable to make it react in the ratio of 1-0.5 mol. 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) Photopolymerization initiator The photopolymerization initiator is not particularly limited as long as it is a commonly used photopolymerization initiator. For example, 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-phenyl Propan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2- (Hydroxy- -Propyl) ketone, benzophenone, 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 compounding quantity of a photoinitiator is 1-30 mass parts with respect to 100 mass parts of active energy ray-curable resins which have at least 2 ethylenically unsaturated bond in 1 molecule, Preferably it is 5-20. Part by mass.

(C) Diluent The diluent is, for example, a photopolymerizable monomer that is a reactive diluent, and is sufficient for photocuring an active energy ray-curable resin having at least two ethylenically unsaturated bonds in one molecule. And used to obtain a cured product having acid resistance, heat resistance, alkali resistance and the like. Examples of the photopolymerizable monomer include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, Neopentyl glycol adipate di (meth) acrylate, hydroxypivalic acid neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl di (meth) acrylate, ethylene oxide modified di (meth) phosphate ) Acrylate, allylated cyclohexyl di (meth) acrylate, isocyanurate di (meth) acrylate, trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate Rate, propionic acid modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris (acryloxyethyl) isocyanurate, propionic acid modified dipentaerythritol penta Examples include reactive diluents such as (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 40 parts by mass with respect to 100 parts by mass of the active energy ray-curable resin having at least two ethylenically unsaturated bonds in one molecule. -25 mass parts is preferable.

(D) Titanium oxide Titanium oxide is used for whitening the cured product, and examples thereof 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 a higher whiteness than rutile-type titanium oxide, but has photocatalytic activity, so the resin in the white 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 particles is not particularly limited, and 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 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. The compounding amount of the rutile type titanium oxide is 30 to 800 parts by mass, preferably 50 to 500 parts by mass with respect to 100 parts by mass of the active energy ray-curable resin having at least two ethylenically unsaturated bonds in one molecule. Part.

(E) Epoxy thermosetting compound The epoxy thermosetting compound is a compound having an epoxy group, and in the white curable resin composition, the crosslink density of the cured product is increased and energy ray (for example, UV) irradiation is performed. It is for obtaining the hardened | cured material which can suppress the discoloration by a heat history, and the fall of a reflectance, For example, an epoxy resin can be mentioned. Examples of the epoxy resin include bisphenol A type epoxy resin (bisphenol A type liquid epoxy resin, bisphenol A type modified flexible epoxy resin, nuclear hydrogenated bisphenol A type liquid epoxy resin, etc.), novolac type epoxy resin (phenol novolac type epoxy). Resin, o-cresol novolak type epoxy resin, p-tert-butylphenol novolak type, etc.), bisphenol F type and bisphenol S type epoxy resin obtained by reacting bisphenol F and bisphenol S with epichlorohydrin, cyclohexene oxide group, tri Cycloaliphatic epoxy resin having cyclodecane oxide group, cyclopentene oxide group, tris (2,3-epoxypropyl) isocyanurate, triglycidyl tris (2-hydro Shiechiru) triglycidyl isocyanurate having a triazine ring such as isocyanurate, dicyclopentadiene type epoxy resins, adamantane type epoxy resin. These compounds may be used alone or in combination of two or more.

  The compounding amount of the epoxy thermosetting compound is based on 100 parts by mass of the active energy ray-curable resin having at least two ethylenically unsaturated bonds in one molecule from the viewpoint of obtaining sufficient curability and reflectance. 1 to 75 parts by mass, and 10 to 50 parts by mass is preferable from the viewpoint of balance between curability and punching crack resistance and cupping resistance.

(F) Inorganic compound having an aspect ratio of 5 or more By containing an inorganic compound having an aspect ratio of 5 or more, the cured product is given rigidity and strength, and punch crack resistance is improved. Examples of the inorganic compound having an aspect ratio of 5 or more include potassium titanate whisker, magnesium sulfate whisker, silicon carbide whisker, calcium carbonate whisker, and glass fiber. If the aspect ratio is 5 or more, the punch crack resistance is improved. However, the aspect ratio is preferably 10 or more from the viewpoint of surely improving the punch crack resistance, and in addition to further improving the punch crack resistance, the cured product has elasticity. An aspect ratio of 15 or more is particularly preferable from the viewpoint of imparting. These compounds may be used alone or in combination of two or more.

  The amount of the inorganic compound having an aspect ratio of 5 or more is not particularly limited. For example, the lower limit of the amount of the inorganic compound having an aspect ratio of 5 or more is determined by punching the cured product with respect to 100 parts by mass of the active energy ray-curable resin having at least two ethylenically unsaturated bonds in one molecule. It is 4 parts by mass from the viewpoint of reliably obtaining crack resistance, and 5 parts by mass is preferred from the viewpoint of obtaining cupping resistance in addition to the punching crack resistance of the cured product, and a point that improves the punching crack resistance and cupping resistance in a balanced manner. To 10 parts by mass is particularly preferable. Moreover, the upper limit of the compounding quantity of the inorganic compound whose aspect ratio is 5 or more is the punching of hardened | cured material with respect to 100 mass parts of active energy ray-curable resins which have at least 2 ethylenically unsaturated bond in 1 molecule. It is 100 parts by mass from the viewpoint of preventing a decrease in crack resistance, and 80 parts by mass is preferable from the viewpoint of preventing a decrease in cupping resistance in addition to the punching crack resistance of a cured product. 60 mass parts is especially preferable from the point which prevents the fall of this reliably.

(G) Phenol compound In the white curable resin composition of the present invention, a phenol compound may be further blended in addition to the components (A) to (F). By containing a phenol type compound, the fall of the reflectance after a heating is suppressed about hardened | cured material. The phenolic compound is, for example, the following general formula (I)

(Wherein R ¹ and R ² each independently represents a methyl group, a hydrogen atom or a t-butyl group).

  The compounding quantity of the phenol type compound shown to general formula (I) can be selected suitably. For example, the lower limit of the compounding amount of the phenolic compound is that the reflectance after heating is reduced with respect to 100 parts by mass of the active energy ray-curable resin having at least two ethylenically unsaturated bonds in one molecule. From the point of suppression, 0.1 part by mass is preferable, and 1 part by mass is particularly preferable from the viewpoint of surely suppressing a decrease in reflectance after heating. The upper limit of the compounding amount of the phenolic compound is that the cured product turns brown with respect to 100 parts by mass of the active energy ray-curable resin having at least two ethylenically unsaturated bonds in one molecule. 10 parts by mass is preferable from the viewpoint of preventing, and 5 parts by mass is particularly preferable from the viewpoint of preventing the photoradical polymerization reaction in the exposure step from being inhibited due to the increase of the phenolic hydroxyl group, thereby reducing the sensitivity.

(H) Urethane acrylate In the white curable resin composition of the present invention, in addition to the components (A) to (F), urethane acrylate may be further blended. Urethane acrylate is used to further improve the cupping resistance of the cured product. The urethane acrylate is not particularly limited as long as it is a compound obtained by reacting urethane resin with acrylic acid which is a radically polymerizable unsaturated monocarboxylic acid. The urethane resin is obtained by reacting a compound having two or more isocyanate groups in one molecule with a polyol compound having two or more hydroxyl groups in one molecule.

  Examples of the compound having two or more isocyanate groups in one molecule include hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), methylene diisocyanate (MDI), methylenebiscyclohexyl isocyanate, trimethylhexamethyl diisocyanate, Examples thereof include diisocyanates such as hexane diisocyanate, hexamethylamine diisocyanate, methylenebiscyclohexyl isocyanate, toluene diisocyanate, 1,2-diphenylethane diisocyanate, 1,3-diphenylpropane diisocyanate, diphenylmethane diisocyanate, and dicyclohexylmethyl diisocyanate. These compounds may be used alone or in combination of two or more.

Polyol compounds having two or more hydroxyl groups in one molecule include ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butylene glycol, 1,3-butylene glycol, 1,2-butylene glycol, 1, 5-pentanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, neopentyl glycol, 1,6-hexanediol, 2,2-diethyl-1,3- C ₂ -C ₂₂ alkanediols such as propanediol, 3,3-dimethylolheptane, 2-ethyl-2-butyl-1,3-propanediol, 1,12-dodecanediol, 1,18-octadecanediol, 2-butene-1,4-diol, 2,6-dimethyl-1-octene-3,8-dioe Aliphatic diols such as alkene diols; alicyclic diols such as 1,4-cyclohexanediol and 1,4-cyclohexanedimethanol; glycerin, 2-methyl-2-hydroxymethyl-1,3-propanediol, 2 , 4-dihydroxy-3-hydroxymethylpentane, 1,2,6-hexanetriol, trimethylolethane, trimethylolpropane, 2-methyl-2-hydroxymethyl-1,3-propanediol, 2,4-dihydroxy- Aliphatic triols such as 3- (hydroxymethyl) pentane and 2,2-bis (hydroxymethyl) -3-butanol; polyols having four or more hydroxyl groups such as tetramethylolmethane, pentaerythritol, dipentaerythritol and xylitol Can be mentioned. These compounds may be used alone or in combination of two or more.

  Examples of commercially available urethane acrylates include “purple light UV-1400B”, “purple light UV-1700B”, “purple light UV-6300B”, “purple light UV-7510B” manufactured by Nippon Synthetic Chemical Co., Ltd., “ Purple light UV-7600B, Purple light UV-7605B, Purple light UV-7610B, Purple light UV-7620EA, Purple light UV-7630B and Purple light UV-7640B, manufactured by Negami Kogyo Co., Ltd. "Resin UN-9000H", "Art Resin UN-3320HA", "Art Resin UN-3320HC", "Art Resin UN-3320HS" and "Art Resin UN-901T", "NK Oligo manufactured by Shin-Nakamura Chemical Co., Ltd." U-4HA "," NK Oligo U-6HA "," NK Oligo U-6LPA "," NK Oligo U-15HA " , “NK Oligo UA-32P”, “NK Oligo U-324A” and “NK Oligo U-6H”, “EBECRYL1204”, “EBECRYL1205”, “EBECRYL215”, “EBECRYL230”, “manufactured by Daicel Cytec Co., Ltd.” EBECRYL244, EBECRYL245, EBECRYL264, EBECRYL265, EBECRYL1280, EBECRYL285Y, EBECRYL84200, EBECRYL8405, EBECRYL845 , "EBECRYL1290", "EBECRYL1290K", "EBECRYL5129", "EBECRYL2 "0", "EBECRYL220", "EBECRYL284", "EBECRYL8210", "EBECRYL8402" and "EBECRYL9260", "UX-2201", "UX-2301", "UX-3204" and "UX-3204" manufactured by Nippon Kayaku Co., Ltd. “UX-3301”, “UX-4101”, “UX-0937”, “UX-5000”, “UX-5001”, “UX-5002”, “Beamset 575” manufactured by Arakawa Chemical Industries, Ltd., Tojo Examples thereof include “M-313” and “M-315” manufactured by Synthetic Co., Ltd.

  The skeleton of the urethane acrylate is not particularly limited, but those having a large number of acrylic functional groups have remarkable curing shrinkage, and therefore the number of acrylic functional groups in one molecule is preferably 2 to 4. In addition, the weight average molecular weight of urethane acrylate is preferably 1500 because the lower limit of the weight average molecular weight is 1500 from the viewpoint of preventing the artwork film from adhering to the substrate and obtaining the desired cured coating. The upper limit is preferably 3000 from the viewpoint of an excellent cured product. Therefore, for example, “EBECRYL 8405” manufactured by Daicel Cytec Co., Ltd., which is tetrafunctional and has a weight average molecular weight of 2700, and “EBECRYL215” manufactured by Daicel Cytec Co., Ltd. which is bifunctional and has a weight average molecular weight of 1,500 are preferable. The compounding amount of urethane acrylate is 10 to 30 parts by mass from the viewpoint of improving cupping resistance with respect to 100 parts by mass of active energy ray-curable resin having at least two ethylenically unsaturated bonds in one molecule. The amount is preferably 15 to 25 parts by mass.

  In addition to the above-described components, the white curable resin composition of the present invention contains various additive components, for example, an antifoaming agent, an organic solvent, various additives, an extender, and the like as necessary. Can do.

  A well-known thing can be used for an antifoamer, for example, a silicone type, a hydrocarbon type, an acrylic type etc. can be mentioned. The organic solvent is used for adjusting the viscosity and drying property of the white 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, and 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, butyl Examples include acetates such as carbitol acetate. The amount of the organic solvent used is preferably 40 to 500 parts by weight with respect to 100 parts by weight of the active energy ray-curable resin having at least two ethylenically unsaturated bonds in one molecule.

  Examples of various 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 derivatives thereof, guanamine and derivatives thereof, amine imide (AI) and latent curing agents such as polyamines, metal salts of acetylacetone such as acetylacetonate Zn and acetylacetonate Cr, enamines, tin octylates, quaternary sulfonium salts And thermosetting accelerators such as triphenylphosphine, imidazole, imidazolium salt and triethanolamine borate.

  The extender pigment is for increasing the physical strength of the cured product of the white curable resin composition, and examples thereof include silica, barium sulfate, alumina, aluminum hydroxide, talc, mica and the like.

  Although the manufacturing method of the above-described white curable resin composition of the present invention is not limited to a specific method, for example, after blending the above components (A) to (F) and other components at a predetermined ratio as necessary, It can be produced by kneading or mixing at room temperature by a kneading means such as a three-roll, ball mill or sand mill, or 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.

  Next, the coating method of the above-described white curable resin composition of the present invention will be described. First, a method for forming a solder resist film by applying the white curable resin composition of the present invention on a printed wiring board having a circuit pattern formed by etching a copper foil will be described as an example. On a printed wiring board having a circuit pattern formed by etching a copper foil, the white curable resin composition produced as described above is applied to a desired thickness using a method such as a screen printing method or a spray coating method. In order to volatilize the organic solvent in the white curable resin composition, preliminary drying is performed at a temperature of about 60 to 80 ° C. for about 15 to 60 minutes, and the organic solvent is volatilized from the white curable resin composition. Make the surface of the coating film tack-free. Then, the negative film which has the pattern which made translucent other than the land of the said circuit pattern is closely_contact | adhered on the apply | coated white curable resin composition, and an active energy ray (for example, 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 a developing method, a spray method, a shower method, or the like is used. As a dilute alkali aqueous solution used, a 0.5 to 5% sodium carbonate aqueous solution is generally used, but other alkalis can also be used. Subsequently, the target solder resist film can be formed on the printed wiring board by performing post-cure for 20 to 80 minutes with a hot-air circulating dryer or the like at 130 to 170 ° C.

  An electronic circuit unit is formed by soldering an electronic component to the printed wiring board coated with the solder resist film thus obtained by a jet soldering method, a reflow soldering method, or the like. In the example of the coating method described above, a printed wiring board is coated with a solder resist film formed using the curable resin composition of the present invention. However, the curable resin composition of the present invention is formed on a flexible wiring board. You may coat | cover the soldering resist film formed using the curable resin composition of this invention on a flexible wiring board by applying a thing.

  Next, a method for producing a reflective sheet by applying the above-described white curable resin composition of the present invention to the surface of a sheet-like base film will be described as an example. When the white curable resin composition of the present invention is thermally cured to form a reflective film, for example, the surface of the sheet-like base film is treated with an acid and washed, and then the white curable resin composition is applied to the washed surface. Is applied to a desired thickness, for example, 5 to 100 μm, using a method such as screen printing or spray coating. Next, preliminary drying is performed in a hot air furnace or a far-infrared furnace, and the organic solvent is volatilized from the white curable resin composition to make the surface of the coating film tack-free. In the preliminary drying, heating is performed at a temperature of about 60 to 80 ° C. for about 15 to 60 minutes. Next, post-curing is performed by heating for 10 to 80 minutes in a dryer such as a hot-air oven or a far-infrared furnace at 130 to 170 ° C., for example, to thermally cure the coating film on the surface of the base film, and to have a reflective coating Manufacture sheets.

  When the white curable resin composition of the present invention is photocured to form a reflective film, for example, the surface of the sheet-like base film is treated with an acid and washed, and then the white curable resin composition is applied to the washed surface. The product is applied to a desired thickness, for example, 5 to 100 μm, using a screen printing method, a spray coating method, or the like. Next, in order to volatilize the organic solvent in the white curable resin composition, preliminary drying is performed by heating at a temperature of about 60 to 80 ° C. for about 15 to 60 minutes. Thereafter, the applied white curable resin composition is photocured by irradiation with active energy rays (for example, ultraviolet rays). At this time, when a predetermined pattern of the reflective film is formed on the reflective sheet, a negative film having a predetermined pattern portion made translucent is brought into close contact with the applied curable resin composition, and active energy rays are formed thereon. The reflective film having the predetermined pattern is developed by irradiating (for example, ultraviolet rays) and removing the non-exposed areas corresponding to the predetermined pattern with a dilute alkaline aqueous solution. As a developing method, a spray method, a shower method, or the like is used. As a dilute alkali aqueous solution used, a 0.5 to 5% sodium carbonate aqueous solution is generally used, but other alkalis can also be used. Then, a post-cure is performed for 20 to 80 minutes with a hot air circulating dryer or the like at 130 to 170 ° C. to produce a reflective sheet having a target reflective film formed on the sheet-like base film.

  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.

  When the reflective sheet is used as a solar battery back sheet, for example, a polyethylene terephthalate film having a thickness of 40 μm is used as the base film. Moreover, a white curable resin composition is applied to the polyethylene terephthalate film surface so that the film thickness after hardening may be 20-23 micrometers, for example. Furthermore, it is preferable that the coating part of the white curable resin composition is performed on the entire surface or almost the entire surface of the base film surface region facing the back surface of the solar cell module.

  Next, an example of how to use a reflective sheet having a reflective coating formed with the white curable resin composition of the present invention will be described. The reflective sheet of the present invention can be used as a solar battery back sheet by being arranged on the back side of the solar cell module, that is, on the surface opposite to the surface that receives solar radiation. When the reflective sheet of the present invention is used as a solar battery back sheet, 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 sheet and again from the back side of the solar cell module. Since it returns to the inside of the solar cell 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.

  Next, examples of the present invention will be described. However, the present invention is not limited to these examples as long as the gist thereof is not exceeded.

Examples 1 to 15 and Comparative Example 1
Each component shown in Table 1 below is blended in the proportions shown in Table 1 below, mixed and dispersed at room temperature using three rolls, and used in Examples 1 to 15 and Comparative Example 1, white curability. A resin composition was prepared. The numbers in the formulation in Table 1 below indicate parts by mass.

Details of each component in Table 1 are as follows.
(A) Active energy ray-curable resin having at least two ethylenically unsaturated bonds in one molecule. FLX-2089: a carboxyl group-containing resin having a urethane-modified epoxy acrylate structure manufactured by Nippon Kayaku Co., Ltd.
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) Photopolymerization initiator Irgacure 819: Bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide manufactured by Ciba Specialty Chemicals Co., Ltd.
DAROCURE TPO: Ciba Specialty Chemicals Co., Ltd., 2,4,6-trimethylbenzoyldiphenylphosphine oxide.
KAYACURE DETX: Nippon Kayaku Co., Ltd., 2,4-diethylthioxanthen-9-one.
(C) Diluent SR454: Sartomer, ethoxylated trimethylolpropane triacrylate.
DPHA: Nippon Kayaku Co., Ltd. dipentaerythritol hexaacrylate.
(D) Titanium oxide R-680: Ishihara Sangyo Co., Ltd., Rutile type titanium oxide (E) Epoxy thermosetting compound YX-4000: Bixylenol type epoxy resin manufactured by Japan Epoxy Resin Co., Ltd.
EP850: Dainippon Ink & Chemicals, bisphenol A type epoxy resin.
(F) Inorganic compound having an aspect ratio of 5 or more, Tismo D: manufactured by Otsuka Chemical Co., Ltd., potassium titanate fiber.
・ Moss Heidi: Magnesium sulfate whisker manufactured by Ube Materials Co., Ltd.
(G) Phenol-based compound / Smilizer GA-80: manufactured by Sumitomo Chemical Co., Ltd., 3,9-bis [2- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy]- 1,1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5,5] undecane.
(H) Urethane acrylate / EBECRYL 8405: manufactured by Daicel-Cytec Co., Ltd., tetrafunctional, weight average molecular weight 2700.

  In addition, KS-66 is a silicone-based antifoaming agent manufactured by Shin-Etsu Chemical Co., Ltd., the additive R-974 is a thixotropy imparting agent manufactured by Nippon Aerosil Co., Ltd., and DICY-7 is Japan Epoxy Resin ( Co., Ltd., a latent curing agent, Irganox 1010 is an antioxidant manufactured by Ciba Specialty Chemicals Co., Ltd., and melamine is a latent curing agent. EDGAC is diethylene glycol monoethyl ether acetate manufactured by Sanyo Kasei Co., Ltd.

Test piece preparation process After buffing the surface of a printed wiring board (FR-4 substrate, plate thickness 1.6 mm, copper foil thickness 50 μm) having a circuit pattern formed by etching copper foil, the screen printing method was applied. After applying the white curable resin composition, preliminary drying was performed in a BOX furnace at 70 ° C. for 20 minutes (in the furnace: 25 minutes). After preliminary drying, the coating film was exposed to ultraviolet rays (300 to 450 nm) with an exposure apparatus (OMW HMW-680GW) at 400 mJ / cm ² (about 40 seconds), and then at 150 ° C. for 60 minutes in a BOX furnace ( In the furnace: 70 minutes) post cure was performed to form a cured coating film on the printed wiring board. The thickness of the cured coating film was 20-23 μm.

Evaluation (1) Reflectance For the test piece prepared as described above, the reflectance at 450 nm was measured using a spectrophotometer U-3410 (manufactured by Hitachi, Ltd .: φ60 mm integrating sphere). “Initial” means post-curing, “after irradiation” means after 50 J / cm ² UV irradiation (2 minutes), and “after heating” means after heat treatment at 170 ° C. for 100 hours.
(2) Solder heat resistance After the cured coating of the test piece prepared as described above was immersed in a solder bath at 260 ° C. for 30 seconds in accordance with the test method of JIS C-6481, a peeling test with a cellophane tape was set as one cycle. The coating state after repeating this 1 to 3 times was observed visually. As for the observation results, “◎” indicates that no change is observed in the coating even after 3 cycles, “◯” indicates that the coating is slightly changed after 3 cycles, and “○” indicates that the change after 2 cycles is repeated. A film in which a change was observed was evaluated as “Δ”, and a film in which peeling was observed in one cycle was evaluated as “×”.
(3) Punching crack resistance A test piece (5 cm x 5 cm) coated on the entire surface of a copper foil by the same method as in the above test piece preparation process is used as an evaluation substrate, and in accordance with JIS K-5600-5-3, DuPont Using an impact device, a weight of 500 g (punched portion: radius 6 mm) was dropped from a height of 50 cm onto the test piece, and the coating film around the punched portion was observed for cracking and peeling. The observation results were evaluated as “◯” when the coating film was not peeled off, “Δ” when the coating film was slightly peeled, and “X” when the coating film was peeled off.
(4) Cupping resistance The surface of a bonded steel plate (10 cm × 10 cm, thickness 0.8 mm) was washed with xylene, and the oil was completely removed. Using the same method to form a coating film as an evaluation substrate, using a cupping tester in accordance with JIS K-5600-5-2, a steel ball is placed from the back side where the cured coating film of the test piece is not formed. When the test piece was extruded and deformed, the extrusion distance (mm) until cracking and peeling of the cured coating film was measured.

  The evaluation results are shown in Table 2.

  As shown in Table 2 above, Examples 1 to 15 containing an inorganic compound having an aspect ratio of 5 or more had punching crack resistance. Further, Examples 1 to 5 containing an inorganic compound having an aspect ratio of 5 or more with respect to 100 parts by mass of the active energy ray-curable resin having at least two ethylenically unsaturated bonds in one molecule. In 10, 13, and 14, punching crack resistance was further improved, and in addition, cupping resistance was also provided. Furthermore, Example 1 containing 30 to 35 parts by mass of an inorganic compound having an aspect ratio of 5 or more with respect to 100 parts by mass of the active energy ray-curable resin having at least two ethylenically unsaturated bonds in one molecule, In 2, 5, 10 and 13, both the punch crack resistance and the cupping resistance were further improved.

  Furthermore, in Examples 7 to 10 containing a phenol compound, it was possible to suppress a decrease in reflectance after heating. Further, in Examples 6 to 8 further containing urethane acrylate, the cupping resistance was further improved.

  Since the white curable resin composition of the present invention can prevent and suppress the occurrence of cracks in punching and drilling, it can be used, for example, in the field of printed wiring boards and flexible wiring boards and in the field of reflective sheets for solar battery backsheets. High value.

Claims (7)

(A) an active energy ray-curable resin having at least two ethylenically unsaturated bonds in one molecule;
(B) a photopolymerization initiator,
(C) Diluent,
(D) titanium oxide,
(E) an epoxy-based thermosetting compound,
And (F) a white curable resin composition comprising an inorganic compound having an aspect ratio of 5 or more.   (F) 5 to 80 masses of the inorganic compound having an aspect ratio of 5 or more with respect to 100 mass parts of the active energy ray-curable resin (A) having at least two ethylenically unsaturated bonds in the molecule (A). 2 part of white curable resin composition of Claim 1 characterized by the above-mentioned.   The (F) inorganic compound having an aspect ratio of 5 or more is at least one whisker-like compound selected from the group consisting of potassium titanate, magnesium sulfate, silicon carbide, and calcium carbonate. 2. The white curable resin composition according to 2. Furthermore, the following general formula (I)

(Wherein R ¹ and R ² each independently represents a methyl group, a hydrogen atom, or a t-butyl group), and (G) a phenolic compound is contained. The white curable resin composition of any one of thru | or 3.   Furthermore, (H) 10-30 mass parts of urethane acrylate is contained with respect to 100 mass parts of the active energy ray-curable resin having at least two ethylenically unsaturated bonds in the molecule (A). The white curable resin composition according to any one of claims 1 to 4, wherein   The printed wiring board which has a cured film of the white curable resin composition of any one of Claims 1 thru | or 5.   The reflective sheet which has a reflective film formed with the white curable resin composition of any one of Claims 1 thru | or 5.