JP2012150461A - White curable resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a white curable resin composition capable of obtaining a cured material without deterioration in reflectance, resolution and dimensional accuracy and with excellent hiding power and reduced discoloration due to a thermal history.SOLUTION: A white curable resin composition contains (A) carboxyl group-containing photosensitive resin, (B) photopolymerization initiator, (C) diluent, (D) epoxy compound, (E) titanium oxide, and (F) threne blue colorant.

Description

  The present invention provides a white curable resin composition having an excellent hiding power, in particular, a white curable resin composition useful as a solder resist film for a circuit board such as a printed wiring board and a reflective film for a reflective sheet, and the white curable resin composition The present invention relates to a printed wiring board having a cured product of a curable resin composition and a reflective sheet.

  A printed wiring board is used to form a pattern of a conductor circuit on a substrate and to mount electronic components on the soldering land of the pattern by soldering, and the circuit portion excluding the soldering land is used as a permanent protective film. It is covered with a solder resist 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. In addition, the hiding power of the solder resist film is used to prevent the conductor circuit pattern information from being found outside.

  In recent years, with the advancement of technology, the demand for miniaturization and weight reduction has further increased in the electronics field. Accordingly, in order to arrange more compact electronic components at high density, the conductors of printed wiring boards There is a demand for fine pitches, miniaturization, and high accuracy of circuit patterns. Accordingly, higher performance is required for the solder resist film with respect to characteristics such as resolution, dimensional accuracy, and thinning. Therefore, Patent Document 1 proposes a solder resist composition that can conceal the pattern of the conductor circuit even if the solder resist film is thinned by blending a predetermined white pigment and a predetermined color pigment. A white curable resin composition for printed wiring boards, which contains titanium oxide at a high content by blending phthalocyanine and has storage stability, has been proposed.

  However, even if the predetermined coloring pigment proposed in Patent Document 1 is blended, the solder resist film turns yellowish brown due to the heat history when the solder resist composition is applied to the printed wiring board and cured. Thus, there is a problem that the hiding power for the conductor circuit pattern is reduced.

  Moreover, in the white curable resin composition proposed by patent document 2, since it is a pigment with low discoloration by a heat history, it mix | blends phthalocyanine. However, in the white curable resin composition of Patent Document 2, due to the yellowing of the resin component due to the thermal history, the solder resist film turns yellowish brown, resulting in a decrease in the hiding power for the conductor circuit pattern. There is a problem of end.

  In recent years, solar cells have been attracting attention for reducing the environmental load, and in order to improve the power generation efficiency of solar cells, there is a demand for a reflective sheet having high reflectivity and excellent discoloration resistance. .

JP-A-2005-311233 JP2009-238771

  In view of the above circumstances, the object of the present invention is to provide a white curable resin that provides a cured product that has excellent hiding power and suppresses discoloration due to thermal history without impairing various properties such as reflectance, resolution, and dimensional accuracy. An object is to provide a composition.

  Embodiments of the present invention include (A) a carboxyl group-containing photosensitive resin, (B) a photopolymerization initiator, (C) a diluent, (D) an epoxy compound, (E) titanium oxide, and (F) A white curable resin composition comprising a selenium blue colorant. The selenium blue colorant as component (F) is a selenium pigment and means a blue dye having a polycyclic quinone skeleton. Therefore, the selenium blue colorant of the present invention is a selenium dye and is different from the phthalocyanine which is a pigment.

  According to an embodiment of the present invention, the white curable resin composition is characterized by containing 0.003 to 0.055 parts by mass of the (F) selenium blue colorant with respect to 100 parts by mass of the (E) titanium oxide. It is.

  An aspect of the present invention is a white curable resin composition, wherein the titanium oxide (E) is contained in an amount of 40 to 300 parts by mass with respect to 100 parts by mass of the (A) carboxyl group-containing photosensitive resin. .

  An embodiment of the present invention is a white curable resin composition further comprising (G) an inorganic ion exchanger.

  The aspect of this invention is a printed wiring board characterized by having the hardened | cured material which hardened the said white curable resin composition.

  In the aspect of the present invention, when the cured product has a film thickness of 20 μm, the L * value is 70 or more, the a * value is −2.5 to −0.5, and the b * value is −6.0 to −2.5. It is a printed wiring board characterized by being.

  An aspect of the present invention is a reflective sheet having a film obtained by curing the white curable resin composition.

  In addition to titanium oxide, which is a white pigment, by adding a selenium blue colorant, it is possible to suppress discoloration due to thermal history without impairing reflectivity, resolution and dimensional accuracy, and to have excellent hiding power A white curable resin composition can be obtained. In addition, when the cured product of the white curable resin compound of the present invention is applied on the substrate on which the conductor circuit pattern is formed, the difference between the color tone of the cured product on the conductor circuit pattern and the color tone of the cured product on the substrate. Can be reduced. Therefore, the white curable resin composition used as the hardened | cured material excellent in the concealing power with respect to a conductor circuit pattern can be obtained. In the above aspect, by blending a selenium blue colorant, even when the carboxyl group-containing photosensitive resin turns yellow due to thermal history, yellowing as a cured white curable resin composition is suppressed, and the hiding power is reduced. It is thought to prevent the decrease of In other words, although the carboxyl group-containing photosensitive resin is yellowed due to the thermal history, the cured white curable resin composition is suppressed from yellowing due to the discoloration due to the thermal history of the selenium-based blue colorant. This is considered to prevent the hiding power from being reduced.

  The hiding power is further improved by adding 0.003 to 0.055 parts by mass of a selenium blue colorant to 100 parts by mass of titanium oxide. In addition, by adding 40 to 300 parts by mass of titanium oxide to 100 parts by mass of the carboxyl group-containing photosensitive resin, a white cured product that has a high reflectance and a cured product with excellent resolution and dimensional accuracy. Resin composition can be obtained. Furthermore, the ion migration phenomenon in the hardened | cured material of white curable resin composition can be prevented by mix | blending an inorganic ion exchanger also under high temperature and humidity.

  By applying the white curable resin composition of the present invention to a printed wiring board, discoloration due to thermal history can be suppressed without impairing reflectivity, resolution, and dimensional accuracy, and the hiding power to the conductor circuit pattern can be reduced. An excellent solder resist film can be formed. For a cured coating film having a film thickness of 20 μm, the L * value is 70 or more, the a * value is −2.5 to −0.5, and the b * value is −6.0 to −2.5. The white of the film is clear, and for example, a printed wiring board that can efficiently use light emission of a light emitting diode element (LED) can be obtained.

  By applying the white curable resin composition of the present invention to the surface of the sheet-like base film, the reflection having a reflective film in which discoloration due to thermal history is suppressed without impairing the reflectance, resolution and dimensional accuracy. A sheet can be obtained.

  Next, each component of the white curable resin composition of this invention is demonstrated. The white curable resin composition of the present invention comprises (A) a carboxyl group-containing photosensitive resin, (B) a photopolymerization initiator, (C) a diluent, (D) an epoxy compound, and (E) titanium oxide. And (F) a selenium blue colorant.

(A) Carboxyl group-containing photosensitive resin The carboxyl group-containing photosensitive resin is not particularly limited, and is a photosensitive carboxyl group-containing resin having at least one photosensitive unsaturated double bond, photosensitive unsaturated double bond. Any carboxyl group-containing resin having no bond can be used. As an example of the component (A), at least a part of the epoxy group of a polyfunctional epoxy resin having two or more epoxy groups in the molecule is reacted with a radically polymerizable unsaturated monocarboxylic acid such as acrylic acid or methacrylic acid. Mention may be made of polybasic acid-modified epoxy (meth) acrylates obtained by obtaining (meth) acrylates and reacting the produced hydroxyl groups with polybasic acids or anhydrides thereof.

  Any polyfunctional epoxy resin may 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 one having a molecular weight of usually 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 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. There is no restriction | limiting in particular in the reaction method of an epoxy resin and radically polymerizable unsaturated monocarboxylic acid, For example, it can react by heating an epoxy resin and acrylic acid in a suitable diluent.

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.

In the present invention, the polybasic acid-modified unsaturated monocarboxylic oxide epoxy resin can also be used as a photosensitive resin. However, one or more carboxyl groups in the polybasic acid-modified unsaturated monocarboxylic oxide epoxy resin have one or more. It is good also as the photosensitive resin which further introduce | transduced the radically polymerizable unsaturated group by making the glycidyl compound which has a radically polymerizable unsaturated group and an epoxy group react, and also improved photosensitivity.

  The photosensitive resin with improved photosensitivity has a photopolymerization reaction because the radical polymerizable unsaturated group is bonded to the side chain of the polymer skeleton of the precursor photosensitive resin by the reaction of the last glycidyl compound. It has high properties 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. The above-mentioned compounds having one or more radically polymerizable unsaturated groups and epoxy groups may be used alone or in combination of two or more.

  The lower limit of the acid value of the carboxyl group-containing photosensitive resin is 30 mg KOH / g, preferably 40 mg KOH / g, from the viewpoint of reliable alkali development. On the other hand, the upper limit of the acid value is 200 mgKOH / g from the viewpoint of preventing dissolution of the exposed area with an alkali developer, and 150 mgKOH / g is preferable from the viewpoint of preventing moisture resistance of the cured product and preventing deterioration of electrical characteristics.

  The lower limit of the weight average molecular weight of the carboxyl group-containing photosensitive resin is 3000, preferably 5000, from the viewpoint of the toughness of the cured product and the touch drying property. On the other hand, the upper limit of the weight average molecular weight is 200,000, preferably 50,000 from the viewpoint of compatibility with the diluent (C) and the like and smooth alkali developability.

  Examples of commercially available carboxyl group-containing photosensitive resins include ZFR-1124, FLX-2089 (manufactured by Nippon Kayaku Co., Ltd.), Cyclomer P (ACA) Z-250, Cyclomer P ( ACA) Z-300 (manufactured by Daicel Chemical Industries, Ltd.), lipoxy SP-4621 (manufactured by Showa Polymer Co., Ltd.), and the like. These resins may be used alone or in combination of two or more.

(B) Photopolymerization initiator The photopolymerization initiator is not particularly limited as long as it is generally used. For example, oxime initiators, 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-phenylpropane- 1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy -2-propyl Ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tertiarybutylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2- Examples include ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4 diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, and P-dimethylaminobenzoic acid ethyl ester. These may be used alone or in combination of two or more. The compounding quantity of a photoinitiator is 5-25 mass parts with respect to 100 mass parts of carboxyl group-containing photosensitive resin, and 8-20 mass parts is preferable.

(C) Diluent Diluent is, for example, a photopolymerizable monomer that is a reactive diluent, and sufficiently cures the carboxyl group-containing photosensitive resin to have acid resistance, heat resistance, alkali resistance, and the like. Used to get things. 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 compounding quantity of an above-described reactive diluent is 2.0-40 mass parts with respect to 100 mass parts of carboxyl group-containing photosensitive resin, and 10-35 mass parts is preferable.

  Moreover, in order to adjust the viscosity and drying property of a white curable composition as a diluent, it replaces with the said reactive diluent or uses the organic solvent which is a non-reactive diluent with the said reactive diluent. Also good. 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 thereof include acetates such as carbitol acetate and diethylene glycol monoethyl ether acetate. These may be used alone or in combination of two or more. As for the compounding quantity in the case of using an organic solvent, 10-500 weight part is preferable with respect to 100 weight part of carboxyl group-containing photosensitive resin.

(D) Epoxy compound The epoxy compound is for increasing the crosslinking density of the cured product to obtain a cured coating film having sufficient mechanical strength. 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. These compounds may be used alone or in combination of two or more. The compounding quantity of an epoxy compound is 5-50 mass parts with respect to 100 mass parts of carboxyl group-containing photosensitive resin from the point which obtains the coating film of sufficient mechanical strength after hardening, and 10-30 mass parts is preferable. .

(E) 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. These may be used alone or in combination of two or more. The compounding amount of titanium oxide is 30 to 800 parts by mass with respect to 100 parts by mass of the carboxyl group-containing photosensitive resin, and preferably 35 to 500 parts by mass from the viewpoint of the balance between whiteness and resolution. In view of further improving the balance between whiteness and resolution, the amount is particularly preferably 40 to 300 parts by mass.

(F) Selenium blue colorant The selenium blue colorant increases the whiteness by increasing the L * value of the cured product formed from the white curable resin composition and prevents yellowing of the cured product due to thermal history. And is added to increase the hiding power. In particular, when the white curable resin composition of the present invention is used as a solder resist film for a printed wiring board, the difference between the color tone of the cured product on the conductor circuit pattern and the color tone of the cured product on the substrate of the printed wiring board is determined. Since the reduction of the hiding power of the portion can be suppressed by preventing yellowing particularly in the portion on the conductor circuit pattern, a solder resist film having an excellent hiding power can be formed. In addition, by blending a selenium-based blue colorant, compared to the case where the whiteness of the cured product is increased by blending other blue colorants (for example, phthalocyanine-based, anthraquinone-based, dioxazine-based pigments), The resolution and dimensional accuracy of the cured coating are improved.

  Specific examples of the selenium blue colorant include Indanthrene Blue RS (C.I. 69800), Indanthrene Blue BC (C.I. 69825), and the like. Specific products include, for example, “LIONOGEN BLUE6510” manufactured by Toyo Ink Mfg. Co., Ltd., “Slen Blue GA210” manufactured by Sanyo Dye Co., Ltd., “Paliogen Blue” manufactured by BASF Corporation, and manufactured by ICI "Monolight Blue 3R", "Monolight Blue 3RN", etc. are on the market. These may be used alone or in combination of two or more.

  The blending amount of the selenium blue colorant can be appropriately selected so that the a * value and the b * value are within the range where the white color becomes clear while the L * value of the cured product is set to a predetermined value or more. The L * value of the cured product is 70 or more in terms of whiteness, and preferably 80 or more. The a * value is preferably in the range of -2.5 to -0.5 from the viewpoint of suppressing the redness and greenness of the cured product and clarifying the white color, and the copper-colored redness of the conductor pattern coated with the cured product. The range of −2.0 to −1.0 is particularly preferable in that it is prevented from being visually recognized. The b * value is preferably in the range of −6.0 to −2.5 in terms of making the white color clear by suppressing the yellow and purple colors of the cured product, and the copper-colored yellowness of the conductor pattern coated with the cured product. A range of −5.0 to −3.0 is particularly preferable from the viewpoint of preventing visual recognition.

  In the present invention, when the white color condition is adjusted within the range of the above L * value, a * value, and b * value, for example, the lower limit value of the blend amount of the selenium blue colorant is 100 parts by mass of titanium oxide. On the other hand, it is 0.003 parts by mass in terms of setting the L * value to 70 or more while adjusting the white color of the cured product while suppressing redness and yellowness, and the conductor pattern copper coated with the cured product The amount is preferably 0.004 parts by mass from the viewpoint of preventing the color from being visually recognized and enhancing the concealing property, and 0.01 parts by mass is particularly preferable from the viewpoint of obtaining a visually clear whiteness. The upper limit of the blending amount of the selenium blue colorant is that the L * value is 70 or more while controlling the white color of the cured product while suppressing the greenness and purpleness with respect to 100 parts by mass of titanium oxide. 0.055 parts by mass, preferably 0.053 parts by mass in terms of preventing the copper color of the conductor pattern coated with the cured product from being visually recognized and improving the concealment, and providing a visually clear whiteness. In terms of obtaining, 0.050 parts by mass is particularly preferable.

  That is, in the white curable resin composition of the present invention, the above-described components (A) to (F) and the following optional components are determined in consideration of the L * value, a * value, and b * value of the cured product. It will mix | blend with the compounding ratio of.

  In the white curable resin composition of the present invention, in addition to the above components (A) to (F), (G) inorganic ion exchangers and various additive components such as antifoaming agents, Additives, extender pigments, thickeners and the like can be appropriately blended.

(G) Inorganic ion exchanger The inorganic ion exchanger takes in ions of opposite charge and performs ion exchange, so that ionic properties such as chlorine ions and sodium ions remaining in the white curable resin composition of the present invention are obtained. Impurities are captured and fixed, and metal ions that move and become ions by applying a voltage are captured and fixed, so that the ion migration phenomenon in the cured product of the white curable resin composition can be achieved even under high temperature and high humidity conditions. Used to prevent. By preventing this ion migration phenomenon, for example, when the white curable resin composition of the present invention is used for a solder resist film of a printed wiring board, a short circuit between electrodes due to the solder resist film can be prevented.

  The type of the inorganic ion exchanger is not particularly limited, and examples thereof include an anion exchange type, a cation exchange type, and a both ion exchange type. Examples of inorganic ion exchangers include Zr, Sb, Bi, Bi-Sb, Mg-Al, and Zr-Bi, but can be used without any particular limitation.

  Inorganic ion exchangers include, for example, “IXE-100” and “IXE-300” manufactured by Toagosei Co., Ltd. as cation exchangers, and “Toyo Gosei Co., Ltd.” manufactured by Toagosei Co., Ltd. “IXE-500”, “IXE-530”, “IXE-550”, “IXE-700”, “IXE-700F”, “IXE-800”, both ion exchangers, manufactured by Toagosei Co., Ltd. IXE-600 "," IXE-633 "," IXE-6107 "," IXE-6136 "," IXEPLUS-A1 "," IXEPLUS-A2 "," IXEPLUS-B1 ", and the like. These may be used alone or in combination of two or more.

  The inorganic ion exchanger has a cation exchange capacity of 0.2 meq / g or more in terms of Na ions and an anion exchange capacity of 0.2 meq in terms of Cl ions from the viewpoint of suppressing the addition amount to prevent a decrease in coatability. The ion exchange capacity is preferably 0.5 meq / g or less in terms of Na ion, and the anion exchange capacity is preferably 0.5 meq / g or less in terms of Cl ion from the viewpoint of ion trapping. The median diameter (d50) of the inorganic ion exchanger is not particularly limited, but is preferably 2.5 μm or less from the viewpoint of dispersibility in the white curable resin composition of the present invention.

  Although the compounding quantity of an inorganic ion exchanger is not specifically limited, The lower limit is 0.1 mass part from the point which prevents an ion migration phenomenon reliably with respect to 100 mass parts of (A) carboxyl group-containing photosensitive resin. 0.5 parts by mass is particularly preferable from the viewpoint of preventing discoloration due to ion migration. On the other hand, the upper limit is 20 parts by mass from the viewpoint of preventing the increase in the viscosity of the white curable resin composition and providing the coatability with certainty, preventing the decrease in resolution and increasing the undercut value. 10 mass parts is preferable from the point which suppresses reliably.

  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. 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, melamine and its derivatives, guanamine and its derivatives, amine imide (AI) and latent curing agents such as polyamine, metal salts of acetylacetone such as acetylacetonate Zn and acetylacetonate Cr, enamine, tin octylate, Examples thereof include quaternary sulfonium salts, triphenylphosphine, imidazole, imidazolium salts and curing accelerators such as triethanolamine borate. The extender is for increasing the physical strength of the cured product, and examples thereof include silica, barium sulfate, alumina, aluminum hydroxide, talc, and mica. Moreover, organic bentonite etc. can be mentioned as a thickener.

  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 each of the above components at a predetermined ratio, kneading such as a three roll, ball mill, sand mill, etc. at room temperature. It can be produced by kneading or mixing by means, or stirring means such as a super mixer or planetary mixer. Further, prior to the kneading or mixing, if necessary, preliminary kneading or premixing may be performed.

  Below, the coating method of the above-mentioned white curable resin composition of this invention is demonstrated. First, the case where the white curable resin composition of the present invention is applied to a printed wiring board as a solder resist film will be described as an example.

  The white curable resin composition of the present invention produced as described above, for example, on a printed wiring board having a circuit pattern formed by etching a copper foil, screen printing method, roll coater method, bar coater method, spray coater It is applied to the desired thickness using the method, curtain flow coater method, gravure coater method, etc., and heated for about 15 to 60 minutes at a temperature of about 60 to 80 ° C. to volatilize the solvent in the white curable resin composition. Pre-drying is performed 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 white 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 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. Next, the coating film is thermally cured by performing post-cure for 20 to 80 minutes with a hot-air circulating dryer or the like at 130 to 170 ° C., and a cured coating film of the desired white 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 coated with the cured coating film thus obtained by a jet soldering method, a reflow soldering method, or the like.

  Next, an example of a method for producing a reflective sheet by coating the above-described white curable resin composition on the surface of a sheet-like base film will be described. After the surface of the sheet-like base film is washed by acid treatment, for example, the white curable resin composition produced as described above is applied to the washed surface with a desired thickness (for example, 5 to 100 μm) by a predetermined coating means. (Thickness). After coating, preliminary 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 desired white cured coating film, that is, a reflective coating film is formed on the surface of the sheet-like base film to produce a white reflective sheet. it can.

  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.

  As the coating means, printing by a screen printing method using a printing mask is generally used at present, but there is no particular limitation as long as it is a coating means that can be applied uniformly including this. Examples of coating means other than the screen printing method include spray coater, honmelt coater, bar coater, applicator, blade coater, knife coater, air knife coater, curtain flow coater, roll coater, gravure coater, offset printing, dip coater, brush A paint etc. can be mentioned.

  Below, the usage example of the said reflection sheet is demonstrated. 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 a back sheet of a solar cell module, 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 so that the film thickness after hardening may become a predetermined value (for example, 20-23 micrometers). Furthermore, it is preferable that the white curable resin composition is applied on the entire surface or substantially the entire surface of the base film facing the back surface of the solar cell module.

  The white curable resin composition of the present invention can be used for streetlight backlights, LED backsheet surfaces, and the like by an appropriate coating method in addition to the above applications.

  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 1-15, Comparative Examples 1-4
Each component shown in the following Table 1 is blended at the blending ratio shown in the following Table 1, and after preliminary mixing with a stirrer, the mixture is mixed and dispersed at room temperature using three rolls. Examples 1 to 15 and Comparative Examples The white curable resin composition used in 1-4 was prepared. And the prepared white curable resin composition was apply | coated on the board | substrate using the test piece preparation process mentioned later, and the test piece was created. In addition, unless otherwise indicated, the compounding quantity of each component shown in following Table 1 shows a mass part.

Details of each component in Table 1 are as follows.
(A) Carboxyl group-containing photosensitive 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) Photopolymerization initiator Irgacure 819: Bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide manufactured by Ciba Specialty Chemicals.
DAROCURE TPO: Ciba Specialty Chemicals Co., Ltd., 2,4,6-trimethylbenzoyldiphenylphosphine oxide.
(C) Diluent Aronix M245: manufactured by Toagosei Co., Ltd., polyethylene glycol diacrylate.
-EDGAC: Sanyo Chemical Co., Ltd. diethylene glycol monoethyl ether acetate.
(D) Epoxy compound / YX-4000: Boxylenol type epoxy resin manufactured by Japan Epoxy Resin Co., Ltd.
(E) Titanium oxide CR-93: manufactured by Ishihara Sangyo Co., Ltd., rutile titanium oxide.
-Taipei A100: manufactured by Ishihara Sangyo Co., Ltd., anatase type titanium oxide.
(F) Selenium blue colorant LIONOGEN BLUE6510: manufactured by Toyo Ink Manufacturing Co., Ltd.
(G) Inorganic ion exchanger IXE-100: manufactured by Toagosei Co., Ltd., Zr-based cation exchanger, median diameter 1.0 μm.
IXE-700F: manufactured by Toagosei Co., Ltd., Mg-Al anion exchanger, median diameter 1.5 μm.
IXE-6107: manufactured by Toagosei Co., Ltd., Zr-Bi-based amphoteric ion exchanger, median diameter 1.5 μm.
IXE-6136: manufactured by Toagosei Co., Ltd., Zr-Bi-based ion exchanger, median diameter 2.1 μm.
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., DICY-7 is a latent curing agent manufactured by Japan Epoxy Resin Co., Ltd., and melamine is also a latent curing agent. LIONOL BLUE 7350 is a phthalocyanine blue colorant manufactured by Toyo Ink Mfg. Co., Ltd.

Test piece preparation process A glass epoxy substrate (made by Panasonic Electric Works Co., Ltd., double-sided copper-clad laminate R-1766, plate thickness 1.6 mmt, conductor thickness 50 μm) on which a conductive pattern was formed was surface-treated by buffing, and then screened After applying each of the white curable resin compositions of Examples 1 to 15 and Comparative Examples 1 to 4 by a printing method, preliminary drying was performed in a BOX furnace at 80 ° C. for 20 minutes (25 minutes in the BOX furnace). . After preliminary drying, the coating film was exposed to 500 mJ / cm ^{2 with} an exposure apparatus (OMW HMW-680GW) for 1 minute and then developed with a 1% aqueous sodium carbonate solution at 30 ° C. After the development, a post-cure was performed at 150 ° C. for 60 minutes (70 minutes in the BOX furnace) in a BOX furnace to form a cured coating film of a white curable resin composition on a glass epoxy substrate, thereby preparing a test piece. The thickness of the cured coating film was 20 to 23 μm.

Evaluation (1) Concealing power for conductor pattern After the electroless gold plating treatment, the reflow treatment was performed, and then the pre-shear cooker treatment was performed, and the concealing power of the white coating film for the conductor pattern, which was a copper foil, was visually observed. Evaluation was performed according to the following criteria.
(Double-circle): There is no difference in the color tone on a conductor pattern and a base material.
○: Slightly yellowed at the edge of the conductor pattern.
Δ: Some yellowing on the conductor pattern.
X: Yellowing occurred on the conductor pattern.
In the electroless gold plating treatment, the test piece is immersed in an 85 ° C. plating bath containing an electroless nickel plating solution (trade name “Melplate NI-865T”, manufactured by Meltex) for 15 minutes, It was immersed in a 90 ° C. plating tank containing an electroless gold plating solution (trade name “Melplate AU-601”, manufactured by Meltex) for 10 minutes. The reflow treatment was performed at a preheat temperature of 60 to 120 ° C., a temperature increase rate of 1 ° C./second, a peak temperature of 230 ° C., and 30 seconds. The pressure cooker treatment was performed under the conditions of 121 ° C., 100% RH, 72 hours.

(2) Color tone After the electroless gold plating treatment, after the reflow treatment, the test piece subjected to the pre-shear cooker, the lightness (L * value) on the conductive pattern of the glass epoxy substrate and the base material of the glass epoxy substrate The chromatic index (a * value, b * value) was measured with a color difference meter SE2000 (Nippon Denshoku Industries Co., Ltd.).
(3) Reflectance (%)
Initial: With respect to the test piece after post-cure, the reflectance at 450 nm was measured with a spectrophotometer U-3410 (manufactured by Hitachi, Ltd .: φ60 mm integrating sphere).
After irradiation: Light resistance is evaluated. After the post-curing test piece, 50 J / cm ² of UV irradiation (300 to 450 nm UV, 2 minutes) is applied, and then a spectrophotometer U-3410 ) The reflectance of the test piece at 450 nm was measured with Hitachi Ltd. (φ60 mm integrating sphere).
After heating: heat resistance is evaluated. After the post-cure test piece is heated at 170 ° C. for 50 hours, the spectrophotometer U-3410 (manufactured by Hitachi, Ltd .: φ60 mm integrating sphere) is used. The reflectance of the test piece at 450 nm was measured.
(4) Resolution The remaining line and the missing space of the exposed portion formed through a predetermined photomask (line width 30 to 130 μm) were visually confirmed and evaluated.
(5) Undercut Using a photomask with a width of 100 μm, cut the glass epoxy substrate on which the cured coating line was formed, and observed the line from the cut surface. The width (x) on the surface side of the line and the bottom side (deep part) Side) width (y) was measured, and the undercut value was evaluated from (xy) / 2.

(6) Ion migration Instead of the glass epoxy substrate on which the conductor pattern is formed, the cured coating film is applied to the IPC-TM-650 IPC-SM840B B-25 test coupon comb electrode in the same manner as described above. And an imprint voltage of DC 50 V, 85 ° C., 85% R.D. H. The comb pattern after being humidified for 1000 hours was observed with an optical microscope (× 100) and evaluated according to the following criteria.
○: No ion migration occurred.
Δ: Some ion migration occurs, but no short circuit occurs between the comb electrodes.
×: Short-circuited between comb-type electrodes due to migration.

  For Examples 1 to 15 and Comparative Examples 1 to 4, the results of hiding power, color tone, reflectance, resolution, undercut and ion migration for the conductor pattern are shown in Table 2 below.

  From Table 2, the Example which mix | blended the slen system blue colorant was compared with the comparative example 2-4 which mix | blended the comparative example 1 which did not mix | blend the blue colorant, and the phthalocyanine system blue colorant. Yellowing of the cured coating film on the conductor pattern was suppressed. In Examples 1 to 7, the chromaticity index (a * value, b * value) on the conductive pattern of the glass epoxy substrate and the chrominetic index (a * value, b * value) on the base material of the glass epoxy substrate. Is smaller than Comparative Examples 1 to 4 (in the example, the difference in the a * value is 0.2 at the maximum and the difference in the b * value is 0.3 at the maximum, whereas in the comparative example, the difference is a Since the difference in the * value is 0.4 at the minimum and the difference in the b * value is the minimum 0.4), in the examples, the difference in color tone between the conductor pattern and the substrate was reduced. Therefore, each Example was excellent in hiding power with respect to the conductor pattern.

  In particular, from Examples 1 to 5 and Examples 6 and 7, the selenium blue colorant is blended in the range of 0.0036 to 0.0375 parts by mass with respect to 100 parts by mass of titanium oxide, thereby concealing the conductor pattern. Power improved further. In Examples 1 to 5, the a * value was −2.5 to −0.5, and the b * value was −6.0 to −2.5, so that the white color of the cured coating film was It was even clearer.

  The example which mix | blended the slen type | system | group blue colorant is a comparative example 1 which did not mix | blend a blue colorant, and the comparative examples 2-4 which mix | blended the phthalocyanine type | system | group blue colorant, or the reflectance and resolution beyond it. And undercut values were obtained. In particular, from Examples 1 to 3 and Comparative Examples 2 to 4, a cured coating film containing a selenium blue colorant is superior in resolution compared to a cured coating film containing a phthalocyanine blue colorant, The undercut value was small and the dimensional accuracy was good.

  In addition, when an inorganic ion exchanger is further blended from Examples 8 to 14, a white curable resin composition is obtained without impairing the reflectance, resolution, dimensional accuracy, color tone (brightness and chromaticness index) and hiding power. The occurrence of ion migration was reliably prevented. Therefore, it has been found that the short circuit between the electrodes due to the cured coating film can be surely suppressed by blending the inorganic ion exchanger. From Examples 8 to 12 and 14, when the inorganic ion exchanger is blended in the range of 0.1 to 2.0 parts by mass with respect to 100 parts by mass of the carboxyl group-containing photosensitive resin, the resolution decreases. The increase in the undercut value was reliably suppressed. Further, from Example 15, even when anatase type titanium oxide is used instead of rutile type titanium oxide, similarly, when an inorganic ion exchanger is blended, reflectance, resolution, dimensional accuracy, color tone and hiding power are improved. Without impairing, the occurrence of ion migration of the white curable resin composition was reliably prevented.

  The white curable resin composition of the present invention provides a cured product that has excellent hiding power and suppresses discoloration due to thermal history without impairing reflectivity, resolution, and dimensional accuracy. The utility value is high in fields such as a solder resist film and a reflective sheet such as a back sheet of a solar cell module.

Claims (7)

  (A) a carboxyl group-containing photosensitive resin, (B) a photopolymerization initiator, (C) a diluent, (D) an epoxy compound, (E) titanium oxide, and (F) a selenium blue colorant A white curable resin composition comprising:   The white curable resin composition according to claim 1, wherein 0.003 to 0.055 parts by mass of the (F) selenium blue colorant is contained with respect to 100 parts by mass of the (E) titanium oxide. .   The white curable resin composition according to claim 1 or 2, wherein the (E) titanium oxide is contained in an amount of 40 to 300 parts by mass with respect to 100 parts by mass of the (A) carboxyl group-containing photosensitive resin. .   Furthermore, (G) inorganic ion exchanger is contained, The white curable resin composition of any one of Claim 1 thru | or 3 characterized by the above-mentioned.   A printed wiring board comprising a cured product obtained by curing the white curable resin composition according to any one of claims 1 to 4.   The cured product has an L * value of 70 or more, an a * value of −2.5 to −0.5, and a b * value of −6.0 to −2.5 at a film thickness of 20 μm. The printed wiring board according to claim 5.   A reflective sheet comprising a film obtained by curing the white curable resin composition according to claim 1.