JP6325873B2 - Photosensitive resin - Google Patents

Description

  The present invention relates to a photosensitive resin capable of obtaining a cured product excellent in bendability (flexibility) and insulation reliability without impairing basic characteristics such as dryness to touch, developability, low warpage, and sensitivity. It is.

  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. The circuit portion excluding the soldering land is used as an insulating 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.

  Usually, the solder resist film is required to have various characteristics such as dryness to touch, sensitivity, developability, and insulation reliability. Among the printed wiring boards, flexible printed wiring boards (hereinafter sometimes referred to as “FPC”) using a thin film substrate such as polyimide do not crack even when bent in addition to the characteristics of the solder resist film. There is a demand for a solder resist film having low warpage with little warpage caused by bendability (flexibility) and shrinkage after curing.

  Therefore, in Patent Document 1, in order to provide a cured coating film excellent in flexibility, (A) a photosensitive prepolymer having two or more unsaturated double bonds and one or more carboxyl groups in one molecule; (B) Photopolymerization initiator, (C) Diluent, (D) Epoxy compound, (E) Polybutadiene having one or more internal epoxide groups in one molecule, and (F) Photosensitive resin containing polyurethane fine particles Compositions have been proposed.

  However, Patent Document 1 still has a problem that not only the insulation reliability but also the bendability and low warpage are not sufficient.

JP 2002-293882 A

  In view of the above circumstances, an object of the present invention is to provide a photosensitive material capable of obtaining a cured product excellent in bendability (flexibility) and insulation reliability without impairing basic characteristics such as touch drying, low warpage, and sensitivity. Providing a functional resin.

  Embodiments of the present invention include: a) an epoxy resin having two or more epoxy groups in one molecule; b) at least one fatty acid having 10 or more carbon atoms per carboxyl group; and c) ethylenic unsaturation. It is a photosensitive resin which is a reaction product with a group-containing carboxylic acid.

  Embodiments of the present invention include: a) an epoxy resin having two or more epoxy groups in one molecule; b) at least one fatty acid having 10 or more carbon atoms per carboxyl group; and c) ethylenic unsaturation. It is a photosensitive resin obtained by adding d) a polybasic acid and / or polybasic acid anhydride to an unsaturated carboxylic epoxy resin which is a reaction product with a group-containing carboxylic acid.

  Embodiments of the present invention include: a) an epoxy resin having two or more epoxy groups in one molecule; b) at least one fatty acid having 10 or more carbon atoms per carboxyl group; and c) ethylenic unsaturation. To an unsaturated carboxylic acid epoxy resin that is a reaction product with a group-containing carboxylic acid, d) a polybasic acid-modified unsaturated carboxylic acid epoxy resin obtained by adding a polybasic acid and / or polybasic acid anhydride, Furthermore, e) is a photosensitive resin obtained by adding a compound having an epoxy group and an ethylenically unsaturated group and / or a compound having an isocyanate group and an ethylenically unsaturated group.

  An aspect of the present invention is a photosensitive resin in which at least one of the fatty acids is a dibasic acid. In this embodiment, the fatty acid can be used alone or in combination of two or more, but when the fatty acid is used alone, it is composed of a dibasic acid and is a mixture of two or more fatty acids. Contains at least one dibasic acid. Since fatty acids have 10 or more carbon atoms per carboxyl group, fatty acids that are dibasic acids have 20 or more carbon atoms.

  An aspect of the present invention is a photosensitive resin in which at least one of the fatty acids is a linear saturated aliphatic monobasic acid having 18 or more carbon atoms.

  In an aspect of the present invention, the polybasic acid is represented by the following general formula (1):

(Wherein R ² represents a hydrogen atom, a linear or branched alkyl group having 1 to 8 carbon atoms, an aryl group, a carboxyl group, or a hydroxyl group, and m is an integer of 1 to 3). It is a photosensitive resin which is a compound represented by.

  In an embodiment of the present invention, the polybasic acid anhydride is represented by the following general formula (1 '):

(Wherein R ² represents a hydrogen atom, a linear or branched alkyl group having 1 to 8 carbon atoms, an aryl group, a carboxyl group, or a hydroxyl group, and m is an integer of 1 to 3). It is a photosensitive resin which is a compound represented by.

  In an aspect of the present invention, the epoxy resin has the following general formula (2):

(In the formula, R ¹ represents a hydrogen atom, or a linear or branched alkyl group having 1 to 8 carbon atoms or an aryl group, l is an integer of 1 to 3, and n is an integer of 1 to 10. .) Is a photosensitive resin. In this embodiment, an epoxy resin of the general formula (2) which is a biphenyl aralkyl type epoxy resin (biphenyl novolac type epoxy resin) is used.

  According to the present invention, a long-chain fatty acid having a high flexibility and a structure excellent in insulation reliability, combustion resistance, and hydrophobicity, that is, a fatty acid having 10 or more carbon atoms per carboxyl group is converted into an ethylenic group. Along with an unsaturated group-containing carboxylic acid, an ethylenically unsaturated group and a long chain with excellent flexibility, insulation reliability, and combustion resistance by adding to an epoxy resin having two or more epoxy groups in one molecule A modified epoxy resin skeleton containing a fatty acid skeleton can be formed. In addition to the hydroxyl group (mainly secondary) produced by the reaction of the carboxyl group of the long chain fatty acid and / or ethylenically unsaturated group-containing carboxylic acid with the epoxy group of the epoxy resin, a polybasic acid and / or polybasic acid anhydride When a carboxyl group is introduced into the resin by adding a product, it can be solubilized in a weak alkaline aqueous solution (for example, an aqueous sodium carbonate solution, an aqueous potassium carbonate solution, etc.). Thereby, it is resin which has photocurability and developability in the weak alkaline aqueous solution, and the cured product is excellent in bendability, low warpage and insulation reliability.

  Further, a compound having an epoxy group and an ethylenically unsaturated group and / or a compound having an isocyanate group and an ethylenically unsaturated group is added to the resin to which the polybasic acid and / or polybasic acid anhydride is added. If a radically polymerizable unsaturated group is further introduced, a cured product with improved photosensitivity can be obtained. Accordingly, since the photopolymerization reaction of the coating film is further promoted during the exposure, it is possible to cope with the photocuring of the coating film by direct drawing exposure.

  When the fatty acid contains a dibasic acid, the resulting photosensitive resin has a relatively rigid skeleton possessed by the epoxy resin by bonding different epoxy groups of the epoxy resin to each other via the dibasic acid. However, it can be set as the structure bridge | crosslinked by the covalent bond in the highly flexible skeleton originating in a long-chain fatty acid. Thereby, the coating film which hardened the photosensitive resin composition containing the photosensitive resin of this invention or the photosensitive resin of this invention shall have heat resistance and a softness | flexibility. In addition, since the fatty acid contains a dibasic acid, the epoxy resin having a relatively low molecular weight can be adjusted to an appropriate molecular weight, so that curing with excellent touch dryness after drying is maintained while maintaining alkali developability. It becomes possible to use a photosensitive resin as a product.

  According to the invention, the fatty acid contains a linear saturated aliphatic monobasic acid having 18 or more carbon atoms, thereby introducing a structure derived from a long-chain fatty acid having excellent flexibility into the photosensitive resin. Thus, in improving the bendability of the cured coating film, a cohesive force that is considered to be derived from a hydrophobic bond of a linear saturated aliphatic chain having 18 or more carbon atoms is generated in the coating film after drying. As a result, even when a solvent is blended in the photosensitive resin composition containing the photosensitive resin of the present invention, the coating film after preliminary drying, which is a step of volatilizing the solvent, is excellent in touch dryness. Resin composition.

  Next, the photosensitive resin of the present invention will be described in detail. The photosensitive resin group of the present invention includes (1) a) an epoxy resin having two or more epoxy groups in one molecule, and b) at least one fatty acid having 10 or more carbon atoms per carboxyl group. c) photosensitive resin which is a reaction product with ethylenically unsaturated group-containing carboxylic acid (hereinafter sometimes referred to as “(1) resin”), (2) a) two or more epoxies in one molecule An unsaturated carboxylated epoxy resin which is a reaction product of an epoxy resin having a group, b) at least one fatty acid having 10 or more carbon atoms per carboxyl group, and c) a carboxylic acid containing an ethylenically unsaturated group And d) a photosensitive resin obtained by adding a polybasic acid and / or polybasic acid anhydride (hereinafter sometimes referred to as “(2) resin”), (3) a) 2 per molecule. An epoxy resin having at least two epoxy groups and b) An unsaturated carboxylic acid epoxy resin which is a reaction product of at least one fatty acid having 10 or more carbon atoms per ruboxyl group and an carboxylic acid containing an ethylenically unsaturated group; and d) a polybasic acid and And / or a polybasic acid-modified unsaturated carboxylic epoxy resin obtained by adding a polybasic acid anhydride, e) a compound having an epoxy group and an ethylenically unsaturated group, and / or an isocyanate group and an ethylenically unsaturated group. It is a photosensitive resin obtained by adding a group-containing compound (hereinafter sometimes referred to as “(3) resin”). Each of the above components is as follows.

  (1) The resin is a) an epoxy resin having two or more epoxy groups in one molecule, b) at least one fatty acid having 10 or more carbon atoms per carboxyl group, and c) ethylenic unsaturation. It is a reaction product with a group-containing carboxylic acid, photocured by irradiating with ultraviolet rays, and heat-cured by heat treatment.

a) Epoxy resin having two or more epoxy groups in one molecule Any epoxy resin having two or more epoxy groups in one molecule can be used as long as it is a bifunctional or more epoxy resin. The epoxy equivalent of an epoxy resin having two or more epoxy groups in one molecule is not particularly limited, but prevents deterioration in photosensitivity and bendability due to a decrease in the ratio of introduction of ethylenically unsaturated group-containing carboxylic acid and long chain fatty acid. From the point which does, 1000 or less are preferable and 100-500 are especially preferable.

  Examples of the epoxy resin having two or more epoxy groups in one molecule include biphenyl aralkyl type epoxy resin, phenyl aralkyl type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, and silicone-modified. Rubber modified epoxy resin such as epoxy resin, ε-caprolactone modified epoxy resin, phenol novolac type epoxy resin such as bisphenol A type, bisphenol F type, bisphenol AD type, cresol novolac type epoxy resin such as о-cresol novolac type, cyclic fat 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 type Examples thereof include a borac type epoxy resin, a condensate type epoxy resin of a phenol and an aromatic aldehyde having a phenolic hydroxyl group, an epoxy resin containing a fluorene skeleton, and an epoxy resin into which an adamantane skeleton is introduced. Moreover, what introduce | transduced halogen atoms, such as Br and Cl, to these resin can also be used.

  Among these, biphenylaralkyl type epoxy resin and dicyclopentadiene type epoxy resin are preferable from the viewpoint of the photosensitivity of the cured product of the photosensitive resin, bendability, low warpage, and insulation reliability, and from the viewpoint of superior bendability. The following general formula (2)

(In the formula, R ¹ represents a hydrogen atom, or a linear or branched alkyl group having 1 to 8 carbon atoms or an aryl group, l is an integer of 1 to 3, and n is an integer of 1 to 10. .) Is particularly preferred.

Examples of commercially available epoxy resins having two or more epoxy groups in one molecule include NC-3000 (manufactured by Nippon Kayaku Co., Ltd., R ^{1 in the} general formula (2) is a hydrogen atom. Biphenyl aralkyl type epoxy resin), HP-7200H (manufactured by DIC, dicyclopentadiene type epoxy resin) and the like. The above-mentioned epoxy resin having two or more epoxy groups in one molecule may be used alone or in combination of two or more.

b) Fatty acid having 10 or more carbon atoms per carboxyl group Fatty acid having 10 or more carbon atoms per carboxyl group is added to the epoxy group of an epoxy resin having two or more epoxy groups in one molecule. By reacting and the long-chain hydrocarbon structure derived from the fatty acid is introduced into the resin, the flexibility, water resistance and electrical insulation of the cured product of the photosensitive resin can be improved. The fatty acid having 10 or more carbon atoms per carboxyl group is not particularly limited, and either saturated or unsaturated can be used, and either linear or branched can be used. Examples of the fatty acid include a monobasic acid having 10 or more carbon atoms and a dibasic acid having 20 or more carbon atoms, and the monobasic acid and dibasic acid from the viewpoint of compatibility between bendability and dryness to touch. Is preferably linear or branched having 2 or less side chains having 2 or less carbon atoms.

  In addition, while introducing the fatty acid structure into the epoxy resin, different epoxy groups of the epoxy resin are bonded to each other via the fatty acid, so that the relatively rigid skeleton of the epoxy resin is flexible from the long chain fatty acid. The fatty acid is at least from the point of being able to have a structure crosslinked by a covalent bond with a high long-chain hydrocarbon skeleton, and imparting a structure excellent in bending property, heat resistance and chemical resistance of the cured coating film to the epoxy resin. It preferably contains one dibasic acid. Furthermore, in the present invention, it is possible to improve the bendability of the cured coating film by introducing many flexible long-chain hydrocarbon skeletons derived from long-chain fatty acids. In addition to a dibasic acid having a number of 10 or more, a fatty acid, a polyfunctional epoxy resin, and an ethylenically unsaturated group-containing carboxylic acid can be obtained by using a single base having 10 or more carbon atoms per carboxyl group. The molecular weight of the reaction product can be appropriately controlled while improving the composition ratio of the component derived from the long-chain fatty acid. In this way, by adjusting the molecular weight appropriately, it is possible to achieve both dryness of the coated film after drying, solubility in weak alkaline developer (ie, alkali developability) and flexibility of the cured film. It becomes.

  As the monobasic acid, in particular, a linear saturated monobasic acid having 18 or more carbon atoms per carboxyl group is included, so that the aggregation is considered to be derived from the hydrophobic bond of the linear saturated aliphatic chain. Force is generated in the coating after drying, and the coating after pre-drying not only has excellent touch drying properties, but also contains many structures derived from long-chain fatty acids with excellent flexibility. The coating film can have excellent bendability and low warpage.

  The number of carbon atoms per carboxyl group is 10 or more from the viewpoint of obtaining flexibility, hydrophobicity and insulation reliability in the cured coating film. On the other hand, the upper limit of the number of carbon atoms per carboxyl group is not particularly limited, but is preferably 22 or less from the viewpoint of maintaining alkali developability.

  Specific examples of fatty acids having 10 or more carbon atoms per carboxyl group include monobasic acids such as capric acid (decanoic acid: C10), tetradecanoic acid (C11), lauric acid (dodecanoic acid: C12), Pentadecanoic acid (C13), myristic acid (tetradecanoic acid: C14), pentadecylic acid (C15), palmitic acid (hexadecanoic acid: C16), margaric acid (heptadecanoic acid: C17), stearic acid (C18), isostearic acid (C18) Tuberculostearic acid (C19), arachidic acid (C20), behenic acid (C22), lignoceric acid (C23), tetracosanoic acid (C24), hexacosanoic acid (C26), octacosanoic acid (C28), triacontanoic acid (C30) ) And the like.

  Dibasic acids include eicosane diacid (C20), ethyl octadecanedioic acid (C20), eicosadiene diacid (C20), vinyl octadecaenedioic acid (C20), dimethyl eicosadiene diacid (C22), dimethyleico C36 dimer acid by dimerization reaction of unsaturated fatty acids such as sundioic acid (C22), diphenylhexadecanedioic acid (C28), oleic acid (C18), etc., and hydrogenated olefinic double bond of the dimer acid Examples thereof include hydrogenated dimer acid. As a commercial item of the above-mentioned dibasic acid, for example, “SL-20” manufactured by Okamura Seiyaku Co., Ltd., whose main component is eicosane diacid represented by the following formula (3),

  “SB-20” manufactured by Okamura Seiyaku Co., Ltd., whose main component is 8-ethyloctadecanedioic acid represented by the following formula (4),

  Mainly (8E, 12E) -eicosa-8,12-dienedioic acid represented by the following formula (5) and (8E) -11-vinyloctadeca-8-enedioic acid represented by the following formula (6), respectively. "ULB-20" manufactured by Okamura Essential Oil Co., Ltd.

  “IPU-22” manufactured by Okamura Seiyaku Co., Ltd., whose main component is (8E, 12E) -9,12-dimethyl-eicosa-8,12-dienedioic acid, represented by the following formula (7):

  “IPS-22” manufactured by Okamura Seiyaku Co., Ltd., which is mainly composed of 9,12-dimethyleicosanedioic acid represented by the following formula (8),

  “ST-2P” manufactured by Okamura Seiyaku Co., Ltd., whose main component is 8,9-diphenylhexadecanedioic acid represented by the following formula (9),

  "UNIDYM10", "UNIDYM14", "UNIDYM18", "UNIDYM22", "UNIDYM35" made by Arizona Chemical, whose main component is C36 dimer acid having an olefinically unsaturated double bond, olefinic unsaturation of the C36 dimer acid Examples thereof include “Pripol 1010” manufactured by Croda, which is a hydrogenated dimer acid in which a double bond is hydrogenated.

  The above fatty acids having 10 or more carbon atoms per carboxyl group may be used alone or in combination of two or more.

  The reaction method of an epoxy resin having two or more epoxy groups in one molecule and at least one fatty acid having 10 or more carbon atoms per carboxyl group may be a known method, for example, the above epoxy resin And a reaction method in which the fatty acid is heated in a suitable diluent.

  Although the ratio (preparation ratio) of the fatty acid having 10 or more carbon atoms per carboxyl group in the photosensitive resin is not particularly limited, the lower limit value is from the point of further improving the bendability and the insulation reliability. 15 mass% is preferable, and 18 mass% is especially preferable from the point which improves a bendability reliably. On the other hand, the upper limit is preferably 50% by mass and particularly preferably 30% by mass from the viewpoint of maintaining good photosensitivity by appropriately maintaining the amount of the ethylenically unsaturated group-containing carboxylic acid introduced.

c) Ethylenically unsaturated group-containing carboxylic acid Ethylenically unsaturated group-containing carboxylic acid reacts with an epoxy group of an epoxy resin having two or more epoxy groups in one molecule, and the epoxy resin is reacted with a photopolymerization initiator. A photocurable group is introduced that can be polymerized by the generated free radicals. The ethylenically unsaturated group-containing carboxylic acid is not particularly limited as long as it imparts photocurability to the epoxy resin. For example, acrylic acid, methacrylic acid, β-acryloxypropionic acid, ω-carboxypolycaprolactone- Examples thereof include carboxylic acids capable of introducing an acryloyl group or a methacryloyl group into an epoxy resin, such as (meth) acrylic acid, crotonic acid, and cinnamic acid. Among these, acrylic acid and methacrylic acid (hereinafter sometimes referred to as (meth) acrylic acid) are preferable, and acrylic acid is particularly preferable. These may be used alone or in combination of two or more.

  The ratio (preparation ratio) of the ethylenically unsaturated group-containing carboxylic acid in the photosensitive resin is not particularly limited, but the lower limit is preferably 2.0% by mass from the viewpoint of good sensitivity, and 3.0% by mass. % Is particularly preferred. On the other hand, the upper limit is preferably 15% by mass from the viewpoint of maintaining good bendability and insulation reliability by appropriately maintaining the amount of fatty acid having 10 or more carbon atoms per carboxyl group. 10% by mass is particularly preferable. The reaction method of the epoxy resin having two or more epoxy groups in one molecule and the ethylenically unsaturated group-containing carboxylic acid is not particularly limited. For example, the epoxy resin and the ethylenically unsaturated group-containing carboxylic acid are appropriately used. A reaction method of heating in a diluent is mentioned.

d) Polybasic acid, polybasic acid anhydride When adding further alkali developability to the photosensitive resin, (1) Add d) polybasic acid and / or polybasic acid anhydride to the resin. A polybasic acid-modified unsaturated carboxylic acid epoxy resin, that is, (2) resin is obtained.

  Polybasic acid, polybasic acid anhydride is a hydroxyl group and ethylenically unsaturated group-containing carboxylic acid produced by reaction of the epoxy resin with at least one fatty acid having 10 or more carbon atoms per carboxyl group A free carboxyl group is introduced into the epoxy resin by reacting with the hydroxyl group produced by the reaction. The polybasic acid and polybasic acid anhydride to be used are 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, trimellitic acid derivatives, pyromellitic acid and diglycolic acid. Anhydrides are mentioned.

  As the polybasic acid, from the viewpoint of alkali developability, the following general formula (1)

(Wherein R ² represents a hydrogen atom, a linear or branched alkyl group having 1 to 8 carbon atoms, an aryl group, a carboxyl group, or a hydroxyl group, and m is an integer of 1 to 3). From the viewpoint of alkali developability, the polybasic acid anhydride is preferably the following general formula (1 ′) which is an anhydride of the compound represented by the general formula (1).

(Wherein R ² represents a hydrogen atom, a linear or branched alkyl group having 1 to 8 carbon atoms, an aryl group, a carboxyl group, or a hydroxyl group, and m is an integer of 1 to 3). The compound represented by these is preferable.

  In the compound represented by the general formula (1), a hydroxyl group generated by a reaction between a carboxylic acid having a fatty acid and / or an ethylenically unsaturated group and an epoxy group reacts with one of the three carboxyl groups of the above compound. Then, it is introduced into the resin skeleton by an ester bond. At this time, two carboxyl groups can be introduced into the resin per molecule of the compound represented by the general formula (1). Therefore, while introducing many long-chain fatty acid components into the resin, it is possible to introduce into the resin an amount of carboxyl groups necessary to efficiently obtain alkali solubility with a small number of hydroxyl groups. Moreover, since the anhydride of the compound represented by the general formula (1) has a free carboxyl group and an acid anhydride group in one molecule, a carboxylic acid having a fatty acid and / or an ethylenically unsaturated group and an epoxy The hydroxyl group produced by the reaction with the group reacts with the acid anhydride group of the above compound and is introduced into the resin skeleton by an ester bond. The anhydride can also introduce two carboxyl groups into the resin per molecule.

  Therefore, while introducing many long-chain fatty acid components into the resin, it is possible to introduce into the resin an amount of carboxyl groups necessary to efficiently obtain alkali solubility with a small number of hydroxyl groups. Thereby, high flexibility, insulation reliability and hydrophobicity of the cured coating film by introduction of the long-chain fatty acid component and alkali developability after preliminary drying can be achieved at a high level. In particular, the photosensitive resin of the present invention in which the compound represented by the general formula (1) or the anhydride thereof is introduced while designing the same amount of carboxylic acid is used except for the compound represented by the general formula (1) or the anhydride thereof. Compared with the introduced photosensitive resin of the present invention, alkali development can be performed in a shorter time. In addition, these compounds may be used independently and may mix and use 2 or more types in order to adjust alkali developability moderately.

  The ratio of polybasic acid and / or polybasic acid anhydride (preparation ratio) in the photosensitive resin is not particularly limited, but the lower limit is preferably 5.0% by mass from the viewpoint of good developability. 7.0% by mass is particularly preferable. On the other hand, the upper limit value is preferably 15% by mass, particularly preferably 10% by mass, from the viewpoint of reliably preventing a decrease in insulation reliability. (2) The method of reacting the polybasic acid and / or polybasic acid anhydride with the resin is not particularly limited. For example, (1) the resin and the polybasic acid and / or polybasic acid anhydride are appropriately diluted. There is a reaction method in which heating is performed and a catalyst is added as necessary.

e) A compound having an epoxy group and an ethylenically unsaturated group and / or a compound having an isocyanate group and an ethylenically unsaturated group (2) A compound or isocyanate group having an epoxy group and an ethylenically unsaturated group on the carboxyl group of the resin By reacting a compound having an ethylenically unsaturated group with an ethylenically unsaturated group, the ethylenically unsaturated group is further introduced into the photosensitive resin, and the photosensitive resin is further improved in photosensitivity. A basic acid-modified unsaturated carboxylic acid epoxy resin (that is, (3) resin) may be used.

  This photosensitized (3) resin is a precursor of a radical polymerizable unsaturated group obtained by a reaction of a compound having an epoxy group and an ethylenically unsaturated group or a compound having an isocyanate group and an ethylenically unsaturated group. Since it is bonded to the side chain of the polymer skeleton of the photosensitive resin (that is, the resin (2)), it has high photopolymerization reactivity and can have excellent photosensitive characteristics.

  Examples of the compound having an epoxy group and an ethylenically unsaturated group include glycidyl compounds such as glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, and pentaerythritol triacrylate monoglycidyl ether.

  Moreover, as a compound which has an isocyanate group and an ethylenically unsaturated group, the compound which has an isocyanate group and a (meth) acryloyl group is mentioned, for example, Specifically, acryloyl isocyanate, methacryloyl isocyanate, 2-isocyanato Ethyl acrylate, 2-isocyanatoethyl methacrylate, 1,1- (bisacryloyloxymethyl) ethyl isocyanate, 1,1- (bismethacryloyloxymethyl) ethyl isocyanate, reaction product of pentaerythritol triacrylate and isophorone diisocyanate, Examples include the reaction product of hexamethylene diisocyanate and 4-hydroxybutyl acrylate, the reaction product of toluene diisocyanate and 1,4-cyclohexanedimethanol monoacrylate, etc. Can. These compounds may be used alone or in combination of two or more.

  The compound having an epoxy group and an ethylenically unsaturated group or the compound having an isocyanate group and an ethylenically unsaturated group is added to the solution of the polybasic acid-modified unsaturated carboxylic epoxy resin and reacted. The compounding ratio of the compound having an epoxy group and an ethylenically unsaturated group and the compound having an isocyanate group and an ethylenically unsaturated group is not particularly limited. For example, 0.05 to 0 with respect to 1 mol of a carboxyl group introduced into the resin. It is preferable to react at a ratio of 5 mol, and it is particularly preferable to react at a ratio of 0.1 to 0.5 mol from the viewpoint of the photosensitivity and insulation reliability of the composition containing the obtained photosensitive resin. . The reaction temperature is preferably 80 to 120 ° C.

  The solid content acid value of the (2) resin and (3) resin is not particularly limited, but is preferably 50 mgKOH / g to 200 mgKOH / g from the viewpoint of alkali development. If it is less than 50 mgKOH / g, alkali development at a sufficient speed tends to be difficult, and if it exceeds 200 mgKOH / g, it tends to be difficult to maintain the exposure pattern due to swelling of the exposed part by an alkali developer. In addition, the upper limit is more preferably 150 mgKOH / g from the viewpoint of moisture resistance of the cured product and prevention of deterioration of insulation reliability.

  The mass average molecular weight of the photosensitive resin ((1) resin, (2) resin and (3) resin) of the present invention is preferably in the range of 3000 to 50000. If it is less than 3000, the toughness and the touch-drying property of the cured product tend to be lowered. If it exceeds 50000, the alkali developability may be remarkably lowered when alkali developability is imparted. Although the double bond equivalent (henceforth "double bond equivalent") derived from the ethylenically unsaturated group containing carboxylic acid of the photosensitive resin of this invention is not specifically limited, 500-5000 g / eq is preferable. If it is less than 500, the crosslink density by photocuring tends to increase and the warpability tends to deteriorate due to the bendability and curing shrinkage of the cured coating film. If it exceeds 5000, the photocurability becomes low and the required exposure due to the decrease in sensitivity. There is a tendency to increase the amount, and to decrease the chemical resistance and plating resistance of the cured coating film. More preferably, it is 700-3500 from the point which makes the bendability and photosensitivity of a cured coating film compatible.

  In addition, the photosensitive resin of the present invention can be used in combination with other known resins having a carboxyl group. For example, a resin obtained by adding an acid anhydride compound to a hydroxyl group of an epoxy (meth) acrylate, or an epoxy (meta) ) Urethane-modified epoxy acrylates synthesized by condensing acrylates, diisocyanates, dimethylolpropionic acid, dimethylolbutanoic acid and other dialcohols having carboxyl groups, (meth) acrylic acid and styrene and monofunctional (meth) acrylates Examples thereof include a copolymer of an ethylenically unsaturated group-containing compound such as a resin, a resin obtained by adding a compound having an ethylenically unsaturated group and an epoxy group thereto, and the like.

  Next, the usage method of the photosensitive resin of this invention is demonstrated. Here, a method of using the photosensitive resin of the present invention as a resin for producing a photosensitive resin composition for an insulating film will be described as an example. A photopolymerization initiator, a thermosetting compound, a colorant, a diluent (solvent), an additive, an antifoaming agent, and the like are added to the photosensitive resin of the present invention at a predetermined ratio, and at room temperature, a three-roll, ball mill A photosensitive resin composition for an insulating coating can be produced by kneading or mixing by a kneading means such as a sand mill or a stirring means such as a super mixer or a planetary mixer. Further, prior to the kneading or mixing, if necessary, preliminary kneading or premixing may be performed.

  The photopolymerization initiator is not particularly limited as long as it is generally used. For example, oxime ester photopolymerization initiator, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n- Butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2- Propi ) Ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tertiarybutylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2 -Ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4 diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, P-dimethylaminobenzoic acid ethyl ester, 2,4,6-trimethylbenzoyldiphenylphosphine oxide Bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl -Pentylphosphine oxide, (2,4,6-trimethylbenzoyl) ethoxyphenylphosphine oxide, 1,2-octanedione, 1- [4- (phenylthio)-, 2- (O-benzoyloxime)], 2- Propanedion-2-O-benzoyloxime, 1-phenyl-1,2-propanedione-2-O-benzoyloxime, ethanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazole- 3-yl]-, 1- (O-acetyloxime) and the like.

  The thermosetting compound is activated by applying heat to increase the crosslink density of the cured product and impart sufficient mechanical strength and heat resistance to the cured product. And polyfunctional epoxy compounds such as the above-mentioned epoxy resin used for the synthesis of the functional resin.

  Examples of the colorant include a white colorant, a black colorant, a blue colorant, and a yellow colorant. Specific examples of these colorants include metal oxide inorganic pigments such as titanium oxide, organic pigments such as phthalocyanines, perylenes and anthraquinones, and carbons such as acetylene black.

  The diluent (solvent) is used to adjust the viscosity and drying property of the photosensitive resin composition. Diluents (solvents) include, for example, ketones such as methyl ethyl ketone and cyclohexanone, aromatic hydrocarbons such as toluene and xylene, alcohols such as methanol, isopropanol and cyclohexanol, and alicyclic carbonization such as cyclohexane and methylcyclohexane. Petroleum solvents such as hydrogen, petroleum ether, 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 And esters such as diethylene glycol monoethyl ether acetate and butyl carbitol acetate.

  Additives include dispersants such as silane, titanate and alumina coupling agents, dicyandiamide (DICY) and its derivatives, organic acid hydrazide, diaminomaleonitrile (DAMN) and its derivatives, guanamine and its derivatives, melamine And latent hardeners such as amine imide (AI) and polyamine. Examples of antifoaming agents include silicones, hydrocarbons, acrylics, and vinyl ethers.

  Next, an example of how to use the photosensitive resin composition for an insulating coating containing the above-described photosensitive resin of the present invention will be described. Here, a method for forming a solder resist film by coating a photosensitive resin composition containing the photosensitive resin of the present invention on a substrate for a flexible wiring board having a circuit pattern formed by etching a copper foil. Let's take an example.

  The photosensitive resin composition produced as described above is desired on a substrate for a flexible wiring board having a circuit pattern formed by etching a copper foil using a known method such as a screen printing method, a spray coating method, or a bar coater. Apply to a thickness of. After coating, if necessary, preliminary drying is performed by heating at a temperature of about 60 to 80 ° C. for about 15 to 60 minutes to volatilize the solvent in the photosensitive resin composition, and the solvent is volatilized from the photosensitive resin composition. To make the surface of the coating film tack-free. On the coated photosensitive resin composition, a negative film having a light-transmitting pattern other than the land of the circuit pattern is brought into close contact, and ultraviolet rays (for example, in a wavelength range of 300 to 400 nm) are irradiated from above. Then, the coating film is developed by removing the non-exposed areas corresponding to the lands with a dilute alkaline aqueous solution. As the developing method, a spray method, a shower method, or the like is used, and examples of the diluted alkaline aqueous solution used include 0.5 to 5% by mass of an aqueous sodium carbonate solution. Next, the target solder resist film can be formed on the substrate for a flexible wiring board by curing for 20 to 80 minutes with a hot-air circulating dryer or the like at 130 to 170 ° C.

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

Photosensitive resin Physical property measurement conditions The solid content was determined from the mass ratio before and after drying after drying the photosensitive resin at 150 ° C. for 2 hours. The solid content acid value was calculated by first measuring the acid value of the photosensitive resin by a phenolphthalein discoloration method based on alkali neutralization titration, and then multiplying by the solid content ratio. The double bond equivalent was calculated by the solid content mass (g) of the photosensitive resin / the number of moles of ethylenically unsaturated group-containing carboxylic acid.

2. The mass average molecular weight was measured as follows.
It measured using the Tosoh GPC apparatus. The measurement conditions are as follows.
Column: TSK gel (manufactured by Tosoh Corporation, "SuperH4000", "SuperHZ2500")
Detector: Differential refraction Solvent: Tetrahydrofuran Solute concentration: 10mg / mL
Standard material: Standard polystyrene (manufactured by VARIAN, "EASICAL PS-2" (monodisperse sample))
Flow rate: 0.3mL / min
Temperature: 40 ° C

  Synthetic examples of photosensitive resins A-1 to A-11 corresponding to the above (1) resin and A′-1 as a comparative example are shown in Table 1, and photosensitive resin A corresponding to the above (3) resin. Synthesis examples of -12 to A-15 and (2) Synthesis examples of photosensitive resins A-16 to A-26 corresponding to the resin will be described with reference to Table 2.

Photosensitive resin A-1
In a 500 mL separable flask equipped with a stirrer and a reflux condenser, 85.7 g of diethylene glycol monoethyl ether acetate (hereinafter “EDGAC”) and 8-ethyloctadecanedioic acid (Okamura Oil Co., Ltd.) in a nitrogen / air (2: 1) atmosphere SB-20 manufactured by Co., Ltd. 26.97 g, behenic acid 45.77 g, stearic acid 9.71 g, acrylic acid 14.36 g, triphenylphosphine (TPP) 0.65 g, methoxyhydroquinone (MEHQ) 0.43 g were charged and nitrogen was added to the reaction vessel. While stirring at a temperature of 110 ° C. while blowing air (2: 1) at 0.3 mL / sec, the mixture was heated and stirred. Separately, 138.5 g of biphenyl aralkyl type epoxy resin NC-3000 (epoxy equivalent 227 manufactured by Nippon Kayaku Co., Ltd.) in 59.3 g of EDGAC solvent was heated to 80 ° C. and uniformly dissolved, and the resulting solution was put into the flask. The mixture was allowed to heat and stir at 15 ° C. for 15 to 17 hours until the acid value of the reaction solution became 6 mgKOH / g or less. Thereby, photosensitive resin A-1 having a mass average molecular weight of about 5500 to 6500 was obtained. The mass ratio and characteristics of each component of the photosensitive resin A-1 are shown in A-1 in Table 1 below.

  Photosensitive resins A-2 to A-11 and A′-1 were also synthesized in the same manner as the photosensitive resin A-1 in the mass ratio of each component shown in Table 1 below. Photosensitive resins A-2 to A-11 and A'-1 having the characteristics shown in Fig. 1 were obtained.

Photosensitive resin A-12
In a 500 mL separable flask equipped with a stirrer and a reflux condenser, 85.7 g of diethylene glycol monoethyl ether acetate (hereinafter “EDGAC”) and 8-ethyloctadecanedioic acid (Okamura Oil Co., Ltd.) in a nitrogen / air (2: 1) atmosphere SB-20 manufactured by Co., Ltd. 26.97 g, behenic acid 45.77 g, stearic acid 9.71 g, acrylic acid 14.36 g, triphenylphosphine (TPP) 0.65 g, methoxyhydroquinone (MEHQ) 0.43 g were charged and nitrogen was added to the reaction vessel. While stirring at a temperature of 110 ° C. while blowing air (2: 1) at 0.3 mL / sec, the mixture was heated and stirred. Separately, 138.5 g of biphenyl aralkyl type epoxy resin NC-3000 (epoxy equivalent 227 manufactured by Nippon Kayaku Co., Ltd.) in 59.3 g of EDGAC solvent was heated to 80 ° C. and uniformly dissolved, and the resulting solution was put into the flask. The mixture was allowed to heat and stir at 15 ° C. for 15 to 17 hours until the acid value of the reaction solution became 6 mgKOH / g or less. To this reaction product, 39.24 g of hydrogenated trimellitic anhydride (manufactured by Mitsubishi Gas Chemical Co., Ltd., HTMAn) was added and stirred at 100 ° C. for 2 to 3 hours in an air atmosphere. The disappearance of the acid anhydride was confirmed by FT-IR (infrared spectrophotometer). To this reaction solution, 2.84 g of glycidyl methacrylate (manufactured by NOF Corporation, Blemmer GH) was charged and stirred at 110 ° C. for 2 to 3 hours. As a result, photosensitive resin A-12 having a solid content acid value of 75 mgKOH / g and a mass average molecular weight of about 7000 to 9000 was obtained. The mass ratio and characteristics of the above components of the curable resin A-12 are shown in A-12 of Table 2 below.

  The photosensitive resins A-13 to A-26 were also synthesized by the same method as the photosensitive resin A-12 at the ratio of the mass of each component shown in Table 2 below, and the characteristics shown in Table 2 below were obtained. Photosensitive resins A-13 to A-26 were obtained.

Examples 1-26, Comparative Examples 1-5
Ingredients shown in Tables 3 and 4 below were blended in the proportions shown in Tables 3 and 4 below, mixed and dispersed at room temperature using three rolls, and in Examples 1-26 and Comparative Examples 1-5. A photosensitive resin composition containing a photosensitive resin to be used was prepared. In addition, the compounding quantity shown to the following Tables 3 and 4 represents a mass part. Moreover, the blank part of a compounding quantity means 0 mass part.

Test piece preparation process The photosensitive resin composition containing the photosensitive resin prepared as mentioned above was applied as follows, and the test piece was produced.

Photosensitive resin compositions prepared by screen printing after surface treatment of a substrate for a flexible wiring board having a circuit pattern formed on a polyimide film (Kapton 100H manufactured by Toray DuPont Co., Ltd.) with dilute sulfuric acid (3% by mass). After applying the product, preliminary drying was performed in a BOX furnace at 80 ° C. for 20 minutes. After the preliminary drying, a negative film having a pattern in which light is transmitted except for the land of the circuit pattern is brought into close contact with the coating film, and ultraviolet rays are applied to the negative film up to 500 mJ / cm ² using an exposure device (OMW HMW-680GW). Exposed. Then, after developing with a 1% by weight sodium carbonate developer at 30 ° C., curing was performed at 150 ° C. for 60 minutes in a BOX furnace to form a cured coating film on the substrate. A specimen was obtained. The thickness of the cured coating film was 20 to 23 μm.

Evaluation item (1) Dryness to touch The negative film was brought into contact with the coating film after the preliminary drying in the test piece preparation step, and the sticking property of the coating film to the negative film after exposure was evaluated. Evaluation was carried out in three stages: ◯: no sticking, Δ: trace of sticking on the coating film remaining, x: coating of the negative film after peeling off the negative film.

(2) Sensitivity Step sensitivity tablet (21 stages of Kodak) is installed on the substrate that has been subjected to the preliminary drying process in the same manner as the above test piece preparation process, and the amount of ultraviolet light (main peak wavelength 365 nm) irradiated through this step tablet. Was irradiated to 400 mJ / cm ² using an integrating photometer manufactured by Oak Manufacturing Co., Ltd., and was used as a test piece. The test piece was developed with a 1% by weight aqueous sodium carbonate solution at a spray pressure of 2.0 kg / cm ² for 60 seconds. Of the exposed portion, the portion not removed by development was represented by a number (number of steps). The larger the number of steps, the better the photosensitive characteristics. The evaluation was performed in four stages: ◎: 9 steps or more, ○: 8 steps, Δ: 7 steps, ×: 6 steps or less.

(3) Developability The presence or absence of residues on the circuit pattern and the polyimide film after the development in the test piece preparation step was visually evaluated. Evaluation: ○: No residue on the circuit pattern or on the polyimide film, Δ: No residue on the circuit pattern, but a little residue on the polyimide film, ×: Residue on both the circuit pattern or the polyimide film The remaining three steps were performed.

(4) Bendability (flexibility)
A photosensitive resin composition is applied to a polyimide film by a bar coater method, and a test piece (preliminarily dried and post-cured in the same manner as the above-described test piece preparation step) is used. Folding was repeated 180 ° several times by folding, and the occurrence of cracks in the cured coating film during 180 ° bending was observed visually and with a × 200 optical microscope, and the number of times that no cracks were generated was measured. The evaluation was performed in four stages: ◎: 5 times or more, ○: 2 to 4 times, Δ: 1 time, ×: 0 times.

(5) Warpage property After cutting out the test piece prepared in the above-mentioned test piece preparation step to 3 cm × 3 cm, place the cut out test piece gently on a horizontal table so that the top is concave, and apply no external force. Thus, the vertical distance between the four corners of the test piece and the table was measured in a straight scale, and the maximum value was adopted. The evaluation was performed in four stages: ◎: 1 mm or less, ○: more than 1 mm to 3 mm, Δ: more than 3 mm to 5 mm, and x: more than 5 mm.

(6) Insulation reliability A cured coating film obtained by applying the photosensitive composition prepared as described above onto a comb-shaped test pattern (line width 50 μm, line spacing 50 μm) in the same manner as in the test piece preparation step. To form a test piece. The test piece was subjected to 50 V application for 24 hours in a bath at 60 ° C. and a humidity of 95%, and then the test piece was taken out of the bath and the resistance value was measured. The resistance value is 1.0E + 11Ω or more, “」 ”, 1.0E + 9Ω or more, less than 1.0E + 11Ω is“ ◯ ”, 1.0E + 7Ω or more, less than 1.0E + 9Ω is“ △ ”, and less than 1.0E + 7Ω is“ × ”. It was evaluated with.

  The evaluation results of Examples 1 to 11 and Comparative Examples 1 to 3 are shown in Table 3 above, and the evaluation results of Examples 12 to 26 and Comparative Examples 4 to 5 are shown in Table 4 above.

  From Table 3, Examples 1 to 11 using a resin modified with a fatty acid having 10 or more carbon atoms per carboxyl group, that is, the fatty acid structure introduced (1), are dry to touch and sensitive. In addition, good bendability and insulation reliability could be obtained without impairing low warpage. Moreover, when biphenyl aralkyl type epoxy resin was used as the epoxy resin of component a) from Examples 1 and 2, the bendability was further improved. Further, (1) Apart from the resin, developability could also be obtained by using a carboxyl group-containing photosensitive resin in combination.

  On the other hand, Comparative Examples 1 to 3 using only a photosensitive resin into which a fatty acid having 10 or more carbon atoms per carboxyl group is not introduced can not be bent and has excellent insulation reliability. I couldn't.

  From Table 4, in Examples 12 to 26, which were modified with a fatty acid having 10 or more carbon atoms per carboxyl group, that is, (2) resin or (3) resin in which the fatty acid structure was introduced, Good bendability and insulation reliability could be obtained without impairing touch dryness, sensitivity, developability and low warpage. In addition, in Examples 12 to 15 in which e) a compound having an epoxy group and an ethylenically unsaturated group and / or a compound having an isocyanate group and an ethylenically unsaturated group was added, Examples in which the above component e) was not added Compared with 16-26, the sensitivity was further improved while having good dryness to the touch, developability, low warpage, bendability and insulation reliability. In addition, d) Examples using trimellitic anhydride as polybasic acid and polybasic acid anhydride tend to improve developability more than examples using succinic anhydride. It was.

  On the other hand, Comparative Examples 4 to 5 using only a photosensitive resin into which a fatty acid having 10 or more carbon atoms per carboxyl group is not introduced cannot obtain excellent sensitivity, and bendability and insulation reliability. The sex could not be improved in a well-balanced manner.

  Since the photosensitive resin composition containing the photosensitive resin of the present invention is excellent in bendability and insulation reliability, it becomes a cured product having basic characteristics such as dryness to touch, developability, low warpage, and sensitivity. For example, the utility value is high in the field of printed wiring boards (particularly, FPC solder resist films).

Claims (5)

a) an epoxy resin having two or more epoxy groups in one molecule; b) at least one fatty acid having 10 or more carbon atoms per carboxyl group; and c) an ethylenically unsaturated group-containing carboxylic acid. D) a photosensitive resin obtained by adding a polybasic acid to an unsaturated carboxylated epoxy resin as a reaction product ,
The polybasic acid is represented by the following general formula (1)

(Wherein R ² represents a hydrogen atom, a linear or branched alkyl group having 1 to 8 carbon atoms, an aryl group, a carboxyl group, or a hydroxyl group, and m is an integer of 1 to 3). A photosensitive resin which is a compound represented by: a) an epoxy resin having two or more epoxy groups in one molecule; b) at least one fatty acid having 10 or more carbon atoms per carboxyl group; and c) an ethylenically unsaturated group-containing carboxylic acid. The polybasic acid-modified unsaturated carboxylic epoxy resin obtained by adding d) a polybasic acid to the unsaturated carboxylic epoxy resin as a reaction product, and e) having an epoxy group and an ethylenically unsaturated group A photosensitive resin obtained by adding a compound and / or a compound having an isocyanate group and an ethylenically unsaturated group ,
The polybasic acid is represented by the following general formula (1)

(Wherein R ² represents a hydrogen atom, a linear or branched alkyl group having 1 to 8 carbon atoms, an aryl group, a carboxyl group, or a hydroxyl group, and m is an integer of 1 to 3). A photosensitive resin which is a compound represented by: Among the fatty acids, at least one is, the photosensitive resin according to claim 1 or 2 is a dibasic acid. The photosensitive resin according to any one of claims 1 to 3 , wherein at least one of the fatty acids is a linear saturated aliphatic monobasic acid having 18 or more carbon atoms. The epoxy resin has the following general formula (2)

(In the formula, R ¹ represents a hydrogen atom, or a linear or branched alkyl group having 1 to 8 carbon atoms or an aryl group, l is an integer of 1 to 3, and n is an integer of 1 to 10. .) is a compound represented by the claims 1 to 4 any one in the photosensitive resin according to.