JP5392088B2 - Resin composition - Google Patents

Description

  The present invention relates to a resin composition useful as an overcoat material for protecting the electronic circuit surface of a flexible printed circuit board, a flexible printed circuit board whose surface is protected by a cured product of the resin composition, and the flexible printed circuit board incorporated therein. It relates to electronic equipment.

  A flexible printed wiring board (FPC) used for TCP (Tape Carrier Package), COF (Chip On Flexible or Film), etc. is generally a conductor layer formed on one or both sides of a polyester terephthalate or polyimide film. It is mainly comprised from the board | substrate which has (conductor circuit layer), and the surface protective film which protects the surface of this board | substrate. As an insulating protective film for FPC, generally, a method in which a cover lay film in which an adhesive layer is provided on a polyimide film punched into a desired shape is attached to a substrate, or a varnish-like resin composition (over A method is known in which a coating agent) is printed in a desired pattern by screen printing and cured. Since a method using a coverlay film is disadvantageous in terms of workability and cost, a method of coating an overcoat agent by screen printing has become the mainstream. As an overcoating agent for flexible printed wiring boards, for example, Japanese Patent Publication No. 5-75032 discloses a composition comprising an epoxy resin, an imidazole compound and a long-chain dibasic acid anhydride.

  The overcoat agent for a flexible printed wiring board is required to have a material that simultaneously satisfies the performances of solvent resistance, flexibility (bending property), low warpage, and electrical insulation. Therefore, an object of this invention is to provide the resin composition useful as an overcoat agent of a flexible printed wiring board which is excellent in these characteristics.

  As a result of intensive studies to solve the above problems, the present inventors have found that a polyurethane resin having an epoxy group and a urethane structure, and a resin composition containing an epoxy curing agent have excellent characteristics as described above, and The present inventors have found that the resin composition is excellent for overcoat use and completed the present invention. That is, the present invention includes the following contents.

[1] A resin composition for an overcoat of a flexible printed wiring board containing (A) a polyurethane resin having an epoxy group and a urethane structure, and (B) an epoxy curing agent.
[2] The resin composition according to the above [1], wherein the polyurethane resin further has at least one structure selected from a polycarbonate structure, a polydiene structure, a polyester structure and a polyether structure.
[3] The resin composition according to the above [1], wherein the polyurethane resin further has a polycarbonate structure and / or a polydiene structure.
[4] The resin composition according to the above [1], wherein the polyurethane resin further has a polycarbonate structure.
[5] The polyurethane resin is (a) a polyol compound having two or more hydroxyl groups in the molecule, (b) an epoxy compound having one or more hydroxyl groups and one or more epoxy groups in the molecule, and (c) in the molecule. The resin composition according to any one of [1] to [4], which is a polyurethane resin obtained by reacting a polyisocyanate compound having two or more isocyanate groups.
[6] The resin composition according to the above [5], wherein the polyol compound is one or more polyol compounds selected from polycarbonate polyol, polydiene polyol, polyester polyol and polyether polyol.
[7] The resin composition according to the above [5], wherein the polyol compound is a polycarbonate polyol and / or a polydiene polyol.
[8] The resin composition according to the above [5], wherein the polyol compound is a polycarbonate polyol.
[9] The resin composition according to any one of [1] to [8], wherein (B) the epoxy curing agent is an acid anhydride compound.
[10] The resin composition according to any one of [1] to [8], wherein the (B) epoxy curing agent is a tetrabasic acid dianhydride.
[11] The resin composition according to any one of [1] to [10], further including (C) an oxazoline compound.
[12] The resin composition according to [11] above, wherein the (C) oxazoline compound is a bisoxazoline compound.
[13] The resin composition according to any one of [1] to [12], wherein the resin composition is a paste-like resin composition.
[14] The resin composition according to any one of [1] to [13], further including a curing accelerator.
[15] A flexible printed wiring board whose surface is protected with a cured product of the resin composition according to any one of [1] to [14].
[16] An electronic device incorporating the flexible printed wiring board according to [15].
[17] A resin composition comprising (A) a polyurethane resin having an epoxy group and a urethane structure, (B) an epoxy curing agent, and (C) an oxazoline compound.
[18] The resin composition according to the above [17], wherein the polyurethane resin further has a polycarbonate structure and / or a polydiene structure.
[19] The resin composition according to the above [17], wherein the polyurethane resin further has a polycarbonate structure.
[20] The polyurethane resin comprises (a) a polyol compound having two or more hydroxyl groups in the molecule, (b) an epoxy compound having one or more hydroxyl groups and one or more epoxy groups in the molecule, and (c) in the molecule. The resin composition according to any one of [17] to [19], which is a polyurethane resin obtained by reacting a polyisocyanate compound having two or more isocyanate groups.
[21] The resin composition according to the above [20], wherein the polyol compound is a polycarbonate polyol and / or a polydiene polyol.
[22] The resin composition according to the above [20], wherein the polyol compound is a polycarbonate polyol.
[23] The resin composition according to any one of [17] to [22], wherein the epoxy curing agent is an acid anhydride compound.
[24] The resin composition according to any one of [17] to [22], wherein the epoxy curing agent is a tetrabasic acid dianhydride.
[25] The resin composition according to the above [17] to [24], wherein the oxazoline compound is a bisoxazoline compound.
[26] The resin composition according to any one of [17] to [25], wherein the resin composition is a paste-like resin composition.

  The resin composition of the present invention is excellent in solvent resistance, flexibility (bendability), low warpage and electrical insulation, and becomes an excellent resin composition for overcoats of flexible printed wiring boards.

  The “polyurethane resin having an epoxy group and a urethane structure” as the component (A) in the present invention further has a polycarbonate structure, a polydiene structure, a polyester structure or a polyether structure from the viewpoint of sufficiently exerting the effects of the present invention. preferable. Of these structures, a polycarbonate structure and a polybutadiene structure are preferable, and a polycarbonate structure is particularly preferable. Two or more of these structures may be simultaneously contained in one molecule of the polyurethane resin having an epoxy group and a urethane structure.

  The “polyurethane resin having an epoxy group and a urethane structure” is preferably, for example, (a) a polyol compound having two or more hydroxyl groups in the molecule, and (b) one or more hydroxyl groups and one or more epoxy groups in the molecule. It can be obtained by reacting an epoxy compound having (c) a polyisocyanate compound having two or more isocyanate groups in the molecule.

  Examples of the polyol compound having two or more hydroxyl groups in the molecule of the raw material (a) include polycarbonate polyol, polydiene polyol, polyester polyol, and polyether polyol.

  Examples of the polyester polyol include adipate-based polyols such as polyethylene adipate polyol and polybutylene adipate polyol, terephthalic acid-based polyol, and polycaprolactone polyol. Two or more polyol compounds may be used in combination.

  Examples of the polyether polyol include polypropylene glycol, polytetramethylene ether glycol, and polyvinyl ether polyol. Examples of the polyvinyl ether polyol include TOE-2000H (manufactured by Kyowa Hakko Chemical Co., Ltd.).

  Examples of the polydiene polyol include polybutadiene polyol and polyisoprene polyol. As the polydiene polyol, a hydrogenated polydiene polyol such as a hydrogenated polybutadiene polyol or a hydrogenated polyisoprene polyol may be used. As polybutadiene polyol, hydroxyl-terminated liquid polybutadiene mainly having 1,4-bonds, Poly bd R-45HT, R-15HT (manufactured by Idemitsu Kosan Co., Ltd.), hydroxyl-terminated polybutadiene hydride polytail H, polytail HA (Mitsubishi) Chemical Co., Ltd.), terminal hydroxylated polybutadiene G-1000, G-2000, G-3000 (above Nippon Soda Co., Ltd.) mainly having 1,2-bonds, mainly 1,2-bonds Hydrides of terminal hydroxylated polybutadiene resin having GI-1000, GI-2000, GI-3000 (manufactured by Nippon Soda Co., Ltd.) and the like. Examples of the polyisoprene polyol include hydroxyl-terminated liquid isoprene Poly ip, Epol (manufactured by Idemitsu Kosan Co., Ltd.) and the like.

  Examples of the polycarbonate polyol include polycarbonate polyols containing a repeating unit derived from one or more diols among polyols such as linear aliphatic diols, alicyclic diols, and glycerin. Examples of the linear aliphatic diol include 1,6-hexanediol, 1,5-pentanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 2- And methyl-1,8-octanediol. Examples of the alicyclic diol include 1,4-cyclohexanedimethanol.

  Of these polyols, polybutadiene polyol and polycarbonate polyol are preferable from the viewpoint of water resistance, heat resistance and flexibility, and polycarbonate polyol is particularly preferable. As the polybutadiene polyol, polybutadiene diol is particularly preferable, and as the polycarbonate polyol, polycarbonate diol is particularly preferable.

  The number average molecular weight of the polyol is preferably 400 to 5,000. When the number average molecular weight is less than 400, the flexibility of the cured product of the resin composition tends to decrease, and when it exceeds 5,000, the solubility of the polyurethane resin in the solvent tends to decrease.

  The epoxy compound having one or more hydroxyl groups and one or more epoxy groups in the molecule of the raw material (b) includes one or more hydroxyl groups in the molecule, a glycidyl ether structure, a glycidyl ester structure, a glycidyl amine structure, an alicyclic epoxy. And an epoxy compound having one or more epoxy groups selected from a structure and an oxirane ring structure. Examples of commercially available compounds include Epicoat 1001, Epocoat 1004 (manufactured by Japan Epoxy Resin Co., Ltd.), etc., as epoxy compounds having one or more hydroxyl groups and one or more glycidyl ether structures in the molecule. Examples of the epoxy compound having one or more hydroxyl groups and one or more oxirane ring structures include hydroxyl group-terminated epoxidized polybutadiene PB-3600 (Daicel Chemical Industries, Ltd.).

  (B) An epoxy compound having one or more hydroxyl groups and one or more epoxy groups in the molecule is (d) an epoxy compound having two or more epoxy groups in the molecule and (e) an epoxy group that reacts with one in the molecule. It can also be obtained by reacting the above compound having an active hydrogen group.

  Examples of the epoxy compound having two or more epoxy groups in the molecule of the raw material (d) include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F. Type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, dicyclopentadiene type epoxy resin, alkylphenol novolac type epoxy resin, biphenol type epoxy resin, naphthalene type epoxy resin, aromatic aldehyde having phenol and phenolic hydroxyl group Epoxidized products of condensates with triglycidyl isocyanurate, alicyclic epoxy resin, glycidylamine resin, glycidyl ester resin, diglycidyl ether of aliphatic diol Epoxy resins such as diglycidyl ethers of cycloaliphatic diols. These epoxy compounds may be used in combination of two or more.

  Examples of the compound having one or more active hydrogen groups that react with an epoxy group in the molecule of the raw material (e) include compounds having one or more phenolic hydroxyl groups and compounds having one or more carboxyl groups. When there are 3 or more active hydrogen groups, there is a possibility of gelation during the reaction with the epoxy compound, so that the compound (e) preferably has 1 or 2 active hydrogen groups. Examples of the compound having one active hydrogen group include a phenol compound, a thiophenol compound, and a carboxylic acid compound. Examples of the compound having two active hydrogen groups include bisphenol A, bisphenol F, bisphenol S, biphenol, hydroquinone, adipic acid, sebacic acid, dodecanedioic acid, 8,12-eicosadienedioic acid, and eicosadioic acid. Two or more of these compounds may be used in combination.

  The raw materials (d) and (e) can be reacted at a reaction temperature of 80 ° C. to 180 ° C. in a range of usually 1 hour to 8 hours. An organic solvent may be added to the reaction as necessary, and a catalyst may be added if necessary. Examples of the catalyst include nitrogen compounds and phosphorus compounds.

  The polyisocyanate compound having two or more isocyanate groups in the molecule of the raw material (c) includes 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, naphthalene. Examples thereof include diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, tetramethylene xylylene diisocyanate, trimethylhexamethylene diisocyanate, and norbornene diisocyanate. These polyisocyanate compounds may be used in combination of two or more.

  As reaction conditions for the raw materials (a), (b), and (c), for example, the reaction can be performed in an organic solvent at a reaction temperature of 15 ° C. to 120 ° C. and a reaction time of usually 1 to 8 hours. . Moreover, you may react by adding a catalyst if needed.

  The reaction ratio of the raw materials (a), (b), and (c) is as follows: the number of hydroxyl groups in the raw material (a) is Xa, the number of hydroxyl groups in the raw material (b) is Xb, and the number of isocyanate groups in the raw material (c) is In the case of Y, a range in which the value of (Xa + Xb) / Y is 1 to 3 is preferable, and a range in which 1.0 to 2 is further preferable. When this ratio is less than 1.0, the reaction takes place in an excess of isocyanate groups, and it is difficult to control the molecular weight, and when it exceeds 3, it tends to be difficult to increase the molecular weight.

  Moreover, it is preferable to use raw material (a) and raw material (b) in the range of (a) :( b) = 90: 10-10: 90 by weight ratio, and also in the range of 90: 10-30: 70. More preferably it is used. When the weight ratio of the raw material (a) is larger than 90:10, the heat resistance of the cured coating film tends to decrease, and when the weight ratio of the raw material (b) is larger than 10:90, flexibility is not good. There is a tendency to be sufficient.

  Examples of the organic solvent used in the reaction include N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N-methyl-2-pyrrolidone, and tetramethyl. Nitrogen compounds such as urea, sulfur compounds such as dimethyl sulfoxide and diethyl sulfoxide, cyclic ester compounds such as γ-butyrolactone, ketone solvents such as cyclohexanone, ether solvents such as diglyme and triglyme, carb Examples include polar solvents such as ester solvents such as tall acetate, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate. These solvents may be used as a mixture of two or more. Further, if necessary, a nonpolar solvent such as an aromatic hydrocarbon can be appropriately mixed and used.

  The reaction may be carried out by adding a catalyst as necessary. Examples of the catalyst include tetramethylbutanediamine, benzyldimethylamine, triethanolamine, triethylamine, N, N-dimethylpiperidine, α-methylbenzyldimethylamine, N- Examples thereof include tertiary amines such as methylmorpholine and triethylenediemine, and organometallic catalysts such as dibutyltin laurate, dimethyltin dichloride, cobalt naphthenate and zinc naphthenate.

  The number average molecular weight of the component (A) in the present invention is preferably 500 to 100,000. More preferably, it is 2,000-50,000. In the present invention, the number average molecular weight is a value in terms of polystyrene measured by gel permeation chromatography (GPC). The number average molecular weight according to the GPC method is specifically shown by GPC-101 manufactured by Showa Denko KK as a measuring device, Shodex KF-800RH / LF-804 manufactured by Showa Denko KK as a column, and tetrahydrofuran as a mobile phase. Can be calculated at a column temperature of 40 ° C. using a standard polystyrene calibration curve. If the number average molecular weight of the component (A) is less than 500, the cured coating film tends to have insufficient flexibility. If the number average molecular weight exceeds 100,000, the viscosity of the component (A) becomes high and handling becomes difficult. Tend.

  As for the epoxy equivalent of the component (A) in this invention, 500-25,000 are preferable. More preferably, it is 500-10,000. If the epoxy equivalent of the component (A) is less than 500, the flexibility of the cured coating film may be impaired, and if it exceeds 25,000, the crosslinking reaction tends to be insufficient. In the present invention, the epoxy equivalent is a value measured according to JIS K7236.

  The epoxy curing agent as the component (B) in the present invention is not particularly limited as long as it is a compound that crosslinks or polymerizes an epoxy group. Specifically, anionic polymerization catalysts such as imidazole compounds, dicyandiamide, guanamine derivatives, melamine derivatives, polybasic acid hydrazide compounds, aliphatic amine compounds, aromatic amine compounds, polythiol compounds, acid anhydride compounds, phenol novolac Cationic polymerization catalysts such as functional phenol compounds and triphenylphosphonium hexafluoroantimonate are listed.

  Among these epoxy curing agents, acid anhydride compounds are preferred from the viewpoint of reactivity. Examples of the acid anhydride compound include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic acid anhydride, hydrogenated methylnadic acid anhydride, and trialkyl. Tetrahydrophthalic anhydride, dodecenyl succinic anhydride, 5- (2,5-dioxotetrahydro-3-furanyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, trimellitic anhydride, pyropyric anhydride Mellitic acid, benzophenone tetracarboxylic dianhydride, biphenyl tetracarboxylic dianhydride, naphthalene tetracarboxylic dianhydride, oxydiphthalic dianhydride, 3,3'-4,4'-diphenylsulfone tetracarboxylic acid Dianhydride, 1,3,3a, 4,5,9b-hexahydro- -(Tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-C] furan-1,3-dione, ethylene glycol bis (anhydrotrimellitate), styrene and maleic acid copolymerized Examples thereof include polymer-type acid anhydrides such as styrene / maleic acid resins. Among these acid anhydrides, from the viewpoint of ease of three-dimensional crosslinking reaction and reactivity, an acid anhydride group having two or more functional acid anhydrides per molecule is preferable, and tetrabasic acid dianhydride is particularly preferable. .

In the case where a curing agent having an active hydrogen group that reacts with epoxy and does not normally react with a hydroxyl group is used as the epoxy curing agent that is component (B) in the present invention, the number of epoxy groups in component (A) (W _EP ) And the number of active hydrogen groups that react with the epoxy group is preferably 1: 0.2 to 1: 2. When the ratio of the number of active hydrogen groups to the number of epoxy groups is less than 0.2 or exceeds 2.0, the crosslinking reaction tends to be insufficient. Here, “not normally reacting with a hydroxyl group” means that the reaction with the hydroxyl group does not occur at a temperature not higher than the curing temperature (for example, 80 to 200 ° C.) when the resin composition is cured. Epoxy curing agents that have an active group that reacts with an epoxy group and does not normally react with a hydroxyl group include dicyandiamide, guanamine derivatives, polybasic acid hydrazide compounds, aliphatic amine compounds, aromatic amine compounds, and phenolic compounds such as phenol novolac. Is mentioned.
As described above, the “polyurethane resin having an epoxy group and a urethane structure” of the present invention is preferably (a) a polyol compound having two or more hydroxyl groups in the molecule, and (b) one or more hydroxyl groups and one or more in the molecule. It can be obtained by reacting an epoxy compound having an epoxy group and (c) a polyisocyanate compound having two or more isocyanate groups in the molecule.
As described above, when the number of hydroxyl groups in the raw material (a) is Xa, the number of hydroxyl groups in the raw material (b) is Xb, and the number of isocyanate groups in the raw material (c) is Y, the value of (Xa + Xb) / Y is Although the range which becomes 1-3 is preferable, in this case, it is thought that this polyurethane resin has a hydroxyl group.
The molecular weight of the raw material (a) component is Ma, the hydroxyl group equivalent is Za, the molecular weight of the raw material (b) component is Mb, the hydroxyl group equivalent is Zb, the molecular weight of the raw material (c) is Mc, and the isocyanate group equivalent is Zc. The number of functional groups per molecule can be calculated by the following formula. Here, Na represents the number of functional groups per molecule of the hydroxyl group of the raw material (a), Nb represents the number of functional groups per molecule of the hydroxyl group of the raw material (b), and Nc represents the number of functional groups per molecule of the isocyanate group of the raw material (c). And
Na = Ma / Za
Nb = Mb / Zb
Nc = Mc / Zc
Furthermore, the theoretical value of the hydroxyl equivalent of the resin obtained by reacting the raw material (a), the raw material (b) and the raw material (c) at a molar ratio of a: b: c can be calculated by the following equation.
(Ma * a + Mb * b + Mc * c) / (Na * a + Nb * b-Nc * c)
In the case where the “polyurethane resin having an epoxy group and a urethane structure” of the present invention is an embodiment having a hydroxyl group theoretically from the reaction ratio of the raw materials as described above, in particular, as an epoxy curing agent, from the viewpoint of promoting a crosslinking reaction. It is preferable to use an acid anhydride compound that reacts with an epoxy group and a hydroxyl group.
The blending amount of the acid anhydride compound can be adjusted in a preferable amount depending on the hydroxyl group derived from the above calculation formula. The acid anhydride compound can be adjusted based on the total number of hydroxyl groups (W _OH ) and epoxy groups (W _EP ). It is preferable to use it so that the number of anhydride groups is 0.1 to 2.0. If the ratio of the number of acid anhydride groups to the total number of hydroxyl groups and epoxy groups is less than 0.1 or exceeds 2.0, the effect in the crosslinking reaction tends to be insufficient. Here, the acid anhydride group and the hydroxyl group react at an equivalent ratio of 1: 1, and similarly the acid anhydride group and the epoxy group react at an equivalent ratio of 1: 1.
Thus, in the present invention, in the embodiment in which the “polyurethane resin having an epoxy group and a urethane structure” has a hydroxyl group, a system using an acid anhydride compound (particularly, a tetrabasic acid anhydride) as an epoxy curing agent is crosslinked. From the viewpoint of promoting the reaction and improving the solvent resistance and the like, it is preferable. In this case, the hydroxyl group equivalent of the urethane resin is preferably 250 to 50,000, more preferably 1,000 to 25,000. If the hydroxyl equivalent is less than 250, the flexibility of the coating film tends to be impaired, and if it exceeds 50,000, the effect in the crosslinking reaction tends to be insufficient due to a decrease in reactivity with the acid anhydride compound.

  The resin composition of the present invention may further contain an oxazoline compound (C) for the purpose of further improving the insulation reliability. As the oxazoline compound, 2-ethyl-2-oxazoline, 2-propyl-2-oxazoline, 2-butyl-2-oxazoline, 2-octyl-2-oxazoline, 2-cyclohexyl-2-oxazoline, 2-allyl-2 -Oxazoline, 2-phenyl-2-oxazoline, laurylaminoethyloxazoline, dilaurylaminoethyloxazoline, lauryloxyethyloxazoline, 2,2'-bis (2-oxazoline), 2,2'-ethylenebis (2-oxazoline) ), 2,2′-tetramethylenebis (2-oxazoline), 2,2 ′-(1,3-phenylene) bis (2-oxazoline), 2,2 ′-(1,4-phenylene) bis (2 -Oxazoline) and the like. Furthermore, compounds containing an oxazoline skeleton in the polymer such as polyoxazoline compounds containing these oxazoline compounds as monomer units and styrene-2-isopropenyl-2-oxazoline copolymers can also be mentioned. Of these oxazoline compounds, oxazoline compounds having two or more oxazoline skeletons are preferable from the viewpoint of enabling a crosslinking reaction, and bisoxazoline compounds are preferable from the viewpoint of reactivity. Among these, 2,2 '-(1,3-phenylene) bis (2-oxazoline) (hereinafter abbreviated as 1,3-PBO) is particularly preferable. The blending amount of the oxazoline compound is preferably 0.05 to 3.0 in the ratio of the oxazoline group to the acid anhydride group. More preferably, it is 0.1-2.0. If it is less than 0.05 molar equivalent, the effect of adding the oxazoline compound is small, and if it exceeds 3.0, the insulation reliability may be lowered.

  The resin composition of this invention may use together the hardening accelerator which accelerates | stimulates hardening reaction of an epoxy hardening | curing agent as needed. Examples of the curing accelerator include triphenylphosphine, phosphonium borate compound, tetraphenylphosphonium tetraphenylborate, n-butylphosphonium tetraphenylborate, 1,8-diazabicyclo- [5.4.0] -7-undecene (DBU), Examples thereof include metal salts of DBU such as 2-ethylhexanoate, zinc octylate and tin octylate, and urea compounds such as phenyldimethylurea, toluenebisdimethylurea and methylenediphenyldimethylurea.

  Various resin additives can be mix | blended with the resin composition of this invention in the range with which the effect of this invention is exhibited. Resin additives include silica, alumina, barium sulfate, talc, clay, mica powder, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum borate, barium titanate, titanate Inorganic fillers such as strontium, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, barium zirconate and calcium zirconate, organic fillers such as acrylic rubber particles, polyamide fine particles and silicone particles, silane coupling agents , Titanate coupling agents, coupling agents such as aluminum coupling agents, silicone defoaming agents, fluorine defoaming agents, defoaming agents such as acrylic polymer defoaming agents, titanium oxide, zinc oxide, etc. Inorganic pigment, phthalocyanine bull , Organic pigments such as phthalocyanine green, iodine green, disazo yellow, carbon black, colorants such as organic dyes, antioxidants such as hindered phenol compounds, phosphorus compounds, sulfur compounds, hydrazide compounds, benzo UV absorbers such as triazole compounds and hindered amine compounds, phosphorus compounds, flame retardants such as aluminum hydroxide and magnesium hydroxide, leveling agents, thixotropic agents, 2,4,6-trimercapto-s-triazole, Examples thereof include adhesion improvers such as 2,5-dimercapto-1,3,4-thiadiazole.

  The resin composition of the present invention can be prepared by dissolving or dispersing a compounding component containing (A) an epoxy group-containing urethane resin and (B) an epoxy curing agent using a planetary mixer, three rolls, a bead mill, or the like. it can. In the preparation, if necessary, an organic solvent for adjusting the viscosity may be used. The organic solvent used for viscosity adjustment can be the same as the organic solvent used in the above-described reaction. When used as an overcoat for flexible printed wiring boards, it is usually prepared as a paste-like resin composition.

  A flexible printed wiring in which the entire surface or a part of the surface is protected by the resin composition of the present invention by applying the paste-like resin composition of the present invention to a predetermined portion of the flexible printed wiring board and drying the coated surface. A board can be obtained. The drying conditions can be set as appropriate by those skilled in the art depending on the type of paste-like resin composition to be used, but are usually dried at 100 to 200 ° C. for about 1 to 120 minutes. The thickness of the surface protective film to be formed is not particularly limited, but is usually 5 to 100 μm. There is no particular limitation on the flexible printed wiring board whose surface is protected by the resin composition of the present invention, TAB (Tape Automated Bonding) flexible printed wiring board, COF flexible printed wiring board, multilayer flexible printed wiring board, conductive paste Various flexible printed wiring boards such as a printed flexible printed wiring board can be used, but the resin composition of the present invention can be suitably used for overcoats of TAB flexible printed wiring boards and COF flexible printed wiring boards. .

  The flexible printed wiring board whose surface is protected by the resin composition of the present invention is used in a form incorporated in various electronic devices. For example, mobile phones, digital cameras, video cameras, game machines, personal computers, printers, hard disk drives, plasma TVs, liquid crystal TVs, liquid crystal displays, car navigation systems, copiers, fax machines, AV equipment, measuring equipment, medical equipment It is suitably used as internal wiring of various electronic devices such as.

EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated concretely, this invention is not limited to this. In the examples, “part” means “part by mass”. In addition, the hydroxyl group equivalent of the hydroxyl group containing epoxy resin of the synthesis example 1 and the epoxy group containing urethane resin of the synthesis examples 2-6 was calculated | required by calculation. For Synthesis Example 1, an equimolar hydroxyl group is formed with the phenolic hydroxyl group of bisphenol A to be reacted with the epoxy resin (HP-7200). For Epicoat 1001 used in Synthesis Examples 2 to 6, the epoxy group is 1 There are two in the molecule, and based on this assumption and the measured value of epoxy equivalent, the molecular weight is considered to be twice the epoxy equivalent,
Number of hydroxyl groups in one molecule = (molecular weight−57) / (228 + 58)) − 1
From this, the number of hydroxyl groups in one molecule was determined. Here, “57” is the molecular weight of the glycidyl ether group, “228” is the molecular weight of bisphenol A, and “58” is the molecular weight of the compound having a secondary hydroxyl structure generated when the glycidyl ether structure and the phenol group of bisphenol A react. is there.

<Synthesis Example 1> Synthesis of Hydroxyl-Containing Epoxy Resin (E-1) Dicyclopentadiene type epoxy resin HP-7200 (Dainippon Ink Chemical Co., Ltd., epoxy) in a 500 ml flask equipped with a stirrer, thermometer and condenser Equivalent 260) 291.4 g, bisphenol A (Mitsui Chemicals Co., Ltd.) 55.6 g, and ethyl diglycol acetate 150.0 g as a solvent were charged and heated to 70 ° C. in a nitrogen stream to obtain a uniform solution. 2.9 g of triphenylphosphine was added thereto, the temperature was raised to 120 ° C., and the reaction was performed as it was for 5 hours to obtain a hydroxyl group-containing epoxy resin E-1.

Properties of hydroxyl group-containing epoxy resin E-1:
Viscosity 74 Pa · s (25 ° C, E-type viscometer)
70% solids
Number average molecular weight 1,700 (GPC, polystyrene conversion)
Epoxy equivalent 538
Hydroxyl equivalent 711

<Synthesis Example 2> Synthesis of Epoxy Group-Containing Urethane Resin (EU-1) Polycarbonate diol T-6001 (Asahi Kasei Chemicals Corporation, hydroxyl value 115 mgKOH / g) in a 500 ml flask equipped with a stirrer, thermometer and condenser 185. 5 g, 188.8 g of the hydroxyl group-containing epoxy resin E-1 shown in <Synthesis Example 1> and 90.0 g of γ-butyrolactone were charged, and 32.3 g of 2,4-tolylene diisocyanate was stirred at room temperature in a nitrogen stream. Then, 3.5 g of 1% solution of ipsol # 150 of dibutyltin dilaurate (manufactured by Idemitsu Kosan Co., Ltd.) was added, and the product temperature (temperature of the mixture) was raised to 80 ° C. and reacted for 3 hours. After confirming that the absorption based on the isocyanate group disappeared by infrared spectroscopic analysis, the reaction was terminated to obtain an epoxy group-containing urethane resin EU-1.

Properties of epoxy group-containing urethane resin EU-1 Viscosity 107 Pa · s (25 ° C, E-type viscometer)
70% solids
Number average molecular weight 4,100 (GPC, polystyrene conversion)
Epoxy equivalent 1,411
Hydroxyl equivalent 1,476

Synthesis Example 3 Synthesis of Epoxy Group-Containing Urethane Resin (EU-2) Polycarbonate Diol T-6001 (Asahi Kasei Chemicals Corporation, hydroxyl value 115 mgKOH / g) 134 in a 500 ml flask equipped with a stirrer, thermometer and condenser 0.5 g, 41.9 g of Epicoat 1001 (manufactured by Japan Epoxy Resin Co., Ltd., epoxy equivalent 475) as a hydroxyl group-containing epoxy resin, 88.0 g of γ-butyrolactone, ipsol # 150 of dibutyltin dilaurate (manufactured by Idemitsu Kosan Co., Ltd.) 2.1 g of a 1% solution was charged, and 33.7 g of 4,4′-diphenylmethane diisocyanate was added little by little so that the product temperature did not exceed 80 ° C. while stirring at room temperature under a nitrogen stream. After the total amount of 4,4′-diphenylmethane diisocyanate was added, the product temperature was raised to 80 ° C. and reacted for 1 hour. After confirming that the absorption based on the isocyanate group disappeared by infrared spectroscopic analysis, the reaction was terminated to obtain an epoxy group-containing urethane resin EU-2.

Properties of epoxy group-containing urethane resin EU-2 Viscosity: 239 Pa · s (25 ° C., E-type viscometer)
70% solids
Number average molecular weight 5,326 (GPC, polystyrene conversion)
Epoxy equivalent 2,199
Hydroxyl equivalent 2,085

<Synthesis Example 4> Synthesis of epoxy group-containing urethane resin (EU-3) Polycarbonate diol UM-CARB90 (1/3) (produced by Ube Industries, Ltd., diol component) in a 500 ml flask equipped with a stirrer, a thermometer and a condenser Is 1,4-cyclohexanedimethanol / 1,6-hexanediol = 1/3 copolymer carbonate diol, hydroxyl value 126 mgKOH / g) 114.2 g, Epicoat 1001 (Japan Epoxy Resin Co., Ltd.) as a hydroxyl group-containing epoxy resin ), Epoxy equivalent 475) 58.0 g and γ-butyrolactone 198.0 g were charged and stirred at room temperature under a nitrogen stream, 27.8 g of 2,4-tolylene diisocyanate, ipzol # 150 of dibutyltin dilaurate (Idemitsu Kosan) 2.0 g of 1% solution (made by Co., Ltd.) It was allowed to react for 3 hours the temperature was raised to 80 ° C.. After confirming that the absorption based on the isocyanate group disappeared by infrared spectroscopic analysis, the reaction was terminated to obtain an epoxy group-containing urethane resin EU-3.

Properties of epoxy group-containing urethane resin EU-3 Viscosity 65 Pa · s (25 ° C., E-type viscometer)
Solid content 50%
Number average molecular weight 8,034 (GPC, polystyrene conversion)
Epoxy equivalent 1,443
Hydroxyl equivalent 2,928

<Synthesis Example 5> Synthesis of epoxy group-containing urethane resin (EU-4) Polycarbonate diol UM-CARB90 (1/1) (manufactured by Ube Industries, Ltd., diol component) in a 500 ml flask equipped with a stirrer, a thermometer and a condenser Is a copolymer carbonate diol containing 1,4-cyclohexanedimethanol / 1,6-hexanediol = 1/1, hydroxyl group value 124 mg KOH / g) 170.1 g, and polybutadiene diol G-1000 (manufactured by Nippon Soda Co., Ltd.) , Hydroxyl value 72 mgKOH / g) 15.3 g, Epicote 1001 (manufactured by Japan Epoxy Resin Co., Ltd., epoxy equivalent 475) 58.0 g, ethyl diglycol acetate 117.2 g as a hydroxyl group-containing epoxy resin > A 2,4-tolylene distillate with stirring at room temperature Cyanate 34.5 g, was added a 1% solution 2.8g of Ipuzoru # 150 of dibutyltin dilaurate (manufactured by Idemitsu Kosan Co., Ltd.), it was performed by elevating the temperature of the product temperature to 80 ° C. and reacted for 3 hours. After confirming that the absorption based on the isocyanate group disappeared by infrared spectroscopic analysis, the reaction was terminated to obtain an epoxy group-containing urethane resin EU-4.

Properties of epoxy group-containing urethane resin EU-4 Viscosity 267 Pa · s (25 ° C., E-type viscometer)
70% solids
Number average molecular weight 7,723 (GPC, polystyrene conversion)
Epoxy equivalent 2,028
Hydroxyl equivalent 2,139

<Synthesis Example 6> Synthesis of Urethane Resin (U-1) Containing No Epoxy Group Polycarbonate Diol T-6001 (Asahi Kasei Chemicals Co., Ltd., hydroxyl value 115 mgKOH / g) in a 500 ml flask equipped with a stirrer, thermometer and condenser ) 329.1 g and γ-butyrolactone 121.7 g were charged and stirred at room temperature under a nitrogen stream, 45.9 g of 2,4-tolylene diisocyanate, Dibutyltin dilaurate ipzol # 150 (manufactured by Idemitsu Kosan Co., Ltd.) 3.3 g of a 1% solution was added, the product temperature was raised to 80 ° C., and the reaction was performed for 3 hours. After confirming that the absorption based on the isocyanate group disappeared by infrared spectroscopic analysis, the reaction was terminated to obtain an epoxy group-containing urethane resin U-1.

Properties of urethane resin U-1 containing no epoxy group Viscosity: 185 Pa · s (25 ° C., E-type viscometer)
75% solids
Number average molecular weight 8,600 (GPC, polystyrene conversion)
Hydroxyl equivalent 2,541

  The epoxy group-containing urethane resin solution (EU-1) obtained in Synthesis Example 2 is 40.0 g in terms of solid content, tetrabasic acid dianhydride, and B-4400 (Dainippon Ink Chemical Co., Ltd., acid 2.91 g of anhydride equivalent 132), 0.21 g of triphenylphosphine (manufactured by Junsei Chemical Co., Ltd.), 0.8 g of hydrophilic fumed silica A-380 (manufactured by Nippon Aerosil Co., Ltd.) as an inorganic filler After kneading in a three-roll mill, γ-butyrolactone was added to adjust the viscosity to about 20 to 40 Pa · s to prepare a thermosetting resin composition.

  As a bisoxazoline compound, 3.44 g of 1,3-PBO (manufactured by Mikuni Pharmaceutical Co., Ltd., oxazoline group equivalent 108) is newly added, except that B-4400 is 3.64 g and triphenylphosphine is 0.24 g. A thermosetting resin composition was prepared in the same manner as in Example 1.

  40.0 g of the epoxy group-containing urethane resin solution (EU-2) obtained in Synthesis Example 3 in terms of solid content, 2.22 g of 1,3-PBO, 2.26 g of B-4400, and 0 of triphenylphosphine A thermosetting resin composition was prepared in the same manner as in Example 2 except that the amount was .22 g.

  40.0 g of the epoxy group-containing urethane resin solution (EU-3) obtained in Synthesis Example 4 in terms of solid content, 2.07 g of 1,3-PBO, 2.70 g of B-4400, and 0 of triphenylphosphine A thermosetting resin composition was prepared in the same manner as in Example 2 except that the amount was .23 g.

  The epoxy group-containing urethane resin solution (EU-4) obtained in Synthesis Example 5 was 40.0 g in terms of solid content, 3.24 g of 1,3-PBO, 2.64 g of B-4400, and 0 of triphenylphosphine. A thermosetting resin composition was prepared in the same manner as in Example 2 except that the amount was .23 g.

<Reference Example 1>
The urethane resin solution (U-1) not containing an epoxy group obtained in Synthesis Example 6 is 45.8 g in terms of solid content, and HP-7200 (manufactured by Dainippon Ink & Chemicals, Inc., epoxy equivalent) as an epoxy resin. 260) is 4.18 g, B-4400 is 2.13 g, triphenylphosphine is 0.22 g, and A-380 is 1.00 g. A thermosetting resin composition is prepared in the same manner as in Example 1. did.

<Reference Example 2>
The urethane resin solution (U-1) containing no epoxy group obtained in Synthesis Example 6 was 35.0 g in terms of solid content, 15.0 g of HP-7200, 7.62 g of B-4400, and 0 of triphenylphosphine. A thermosetting resin composition was prepared in the same manner as in Reference Example 1 except that the amount was .29 g.

<Reference Example 3>
Thermosetting resin composition as in Reference Example 2 except that 1.99 g of 1,3-PBO is newly added as a bisoxazoline compound, 9.24 g of B-4400 and 0.31 g of triphenylphosphine are used. Was prepared.

≪Evaluation as an overcoat material that protects the electronic circuit surface of flexible printed circuit boards≫
<Evaluation of solvent resistance>
The thermosetting resin compositions prepared in Examples and Reference Examples were screen-printed on a 50 μm-thick polyimide film (Upilex 50S: Ube Industries, Ltd.) using a 200 mesh plate, 120 ° C. for 1 hour, and further 150 ° C. And cured for 2 hours. The hardened surface is rubbed with a cotton swab soaked in acetone with a force of 400 to 500 g, ○ if there is no abnormality, △ if the printed surface is scratched and discolored, △, the printed surface is melted The case where the substrate was exposed was rated as x. The results are shown in Table 1.

<Evaluation of bendability>
The thermosetting resin compositions prepared in Examples and Reference Examples were screen-printed on a 50 μm-thick polyimide film (Upilex 50S: Ube Industries, Ltd.) using a 200 mesh plate, 120 ° C. for 1 hour, and further 150 ° C. And cured for 2 hours. The polyimide film was folded at 180 degrees with the printing surface facing outward. The case where whitening did not occur in the cured film was marked as ◯, and the case where whitening or cracking was observed in the cured film was marked as x. The results are shown in Table 1.

<Evaluation of warpage>
The thermosetting resin compositions prepared in Examples and Reference Examples were screen-printed on a 50 μm-thick polyimide film (Upilex 50S: manufactured by Ube Industries, Ltd.) using a 200 mesh, 10 cm × 10 cm large plate at 120 ° C. After curing for 1 hour, 4 sheets were cut out in a size of 5 cm × 5 cm. These were further cured at 150 ° C. for 2 hours to obtain test pieces. Curing caused the test piece to be warped in a form in which the printed surface became concave. Four test pieces are placed on a smooth glass plate with the printing surface facing up, and the size of the float from the glass plate at the position of one vertex with the largest warpage of each test piece is measured. The average value of was calculated. The results are shown in Table 1.

<Evaluation of electrical insulation reliability>
The thermosetting resin compositions prepared in Examples and Reference Examples were prepared using a 200-mesh plate on a polyimide substrate on which a 30 μm pitch comb-shaped electrode pattern was formed, and L / L on a polyimide film having a thickness of 37.5 μm. A polyimide substrate on which a comb-shaped electrode pattern having S = 15/15 μm and a circuit thickness of 8 μm is formed is screen-printed so as to cover the entire surface of the comb-shaped electrode pattern, and cured at 120 ° C. for 1 hour and further at 150 ° C. for 2 hours. I let you. While applying a voltage of 60 V to this, it was left in an atmosphere of 120 ° C. and a relative humidity of 85%. The holding time until ion migration and a decrease in insulation resistance value (up to 10 ⁶ Ω or less) were observed was measured as HAST (Highly Accelerated Temperature and Humidity Stress Test) endurance time. The results are shown in Table 1.

  As can be seen from Table 1, among the embodiments of the present invention, (A) a polyurethane resin having an epoxy group and a urethane structure, and (B) a resin composition for an overcoat of a flexible printed wiring board containing an epoxy curing agent is Compared with Comparative Examples 1 to 3, the warpage of the printed wiring board was greatly reduced. (C) Examples 2 to 5 further containing an oxazoline compound showed that the warpage was further reduced and the electrical insulation reliability was also excellent. Thus, the thermosetting resin composition of the present invention is excellent in solvent resistance and bendability and achieves both warpage and electrical insulation reliability.

  This application is based on Japanese Patent Application No. 2007-271600 filed in Japan, the contents of which are incorporated in full herein.

Claims (16)

(A) A polyurethane resin having an epoxy group and a urethane structure, and (B) a resin composition for an overcoat of a flexible printed wiring board containing an epoxy curing agent. The resin composition according to claim 1, wherein the polyurethane resin further has one or more structures selected from a polycarbonate structure, a polydiene structure, a polyester structure, and a polyether structure. The resin composition according to claim 1, wherein the polyurethane resin further has a polycarbonate structure and / or a polydiene structure. The resin composition according to claim 1, wherein the polyurethane resin further has a polycarbonate structure. The polyurethane resin is (a) a polyol compound having two or more hydroxyl groups in the molecule, (b) an epoxy compound having one or more hydroxyl groups and one or more epoxy groups in the molecule, and (c) two or more hydroxyl compounds in the molecule. The resin composition of any one of Claims 1-4 which is a polyurethane resin obtained by making the polyisocyanate compound which has an isocyanate group react. The resin composition according to claim 5, wherein the polyol compound is one or more polyol compounds selected from polycarbonate polyol, polydiene polyol, polyester polyol, and polyether polyol. The resin composition according to claim 5, wherein the polyol compound is a polycarbonate polyol and / or a polydiene polyol. The resin composition according to claim 5, wherein the polyol compound is a polycarbonate polyol. (B) The resin composition according to any one of claims 1 to 8, wherein the epoxy curing agent is an acid anhydride compound. (B) The resin composition according to any one of claims 1 to 8, wherein the epoxy curing agent is a tetrabasic acid dianhydride. (C) The resin composition of any one of Claims 1-10 which further contains an oxazoline compound. (C) The resin composition of Claim 11 whose oxazoline compound is a bisoxazoline compound. The resin composition according to any one of claims 1 to 12, wherein the resin composition is a paste-like resin composition. The resin composition according to claim 1, further comprising a curing accelerator. The flexible printed wiring board by which the surface was protected with the hardened | cured material of the resin composition of any one of Claims 1-14. An electronic device incorporating the flexible printed wiring board according to claim 15.