TW202028354A - Resin composition, cured film, printed wiring board with cured film, and method for producing same - Google Patents

Abstract

This resin composition includes a binder resin (a), a thermosetting resin (b), and a flame retardant (c). The binder resin (a) is a polymer having a urethane bond in a molecule, and may also have a carboxy group and/or a photopolymerizable functional group. The flame retardant (c) is an organic phosphorus compound represented by the general formula. In the formula, R2 and R5 are each independently a phenyl group which may have a substituent, a naphthyl group which may have a substituent, or an anthryl group which may have a substituent; R1, R3, R4, and R6 are each independently a hydrogen atom, an alkyl group having 1-4 carbon atoms, a phenyl group which may have a substituent, a naphthyl group which may have a substituent, or an anthryl group which may have a substituent.

Description

Resin composition, cured film, printed wiring board with cured film, and manufacturing method thereof

The present invention relates to a resin composition, a cured film obtained by curing the resin composition, and a printed wiring board provided with the cured film.

In order to maintain insulation reliability on the circuit of the printed wiring board, an insulating thermosetting resin or ultraviolet curable resin is used to form an insulating cured film. There are cases where flame retardancy is required for the insulating cured film, and from the viewpoint of environmental load, non-halogen flame retardants are used (Patent Document 1). [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2016-21243

[The problem to be solved by the invention]

In order to make the insulating cured film on the printed wiring board have sufficient flame retardancy, it is necessary to add a large amount of flame retardant, which may cause the strength or heat resistance of the cured film to decrease. In addition, if liquid flame retardants are used, there is a concern about bleeding. If flame retardants such as phosphinic acid metal salt or aluminum hydroxide are used, the flame retardant may be eluted due to alkali development or chemical treatment after curing. Or the situation of separation. Furthermore, if a flame retardant is added in a large amount in order to improve the flame retardancy, the flexibility of the cured film may decrease.

The object of the present invention is to provide a cured film that has excellent flame retardancy, is hard to cause abnormalities such as bleeding, and is excellent in flexibility, and a resin composition used in the formation of the cured film. [Technical means to solve the problem]

The resin composition of the present invention includes (a) a binder resin, (b) a thermosetting resin, and (c) a flame retardant. (a) The binder resin is a polymer having a urethane bond in the molecule, and may further have a carboxyl group and/or a photopolymerizable functional group. The acid value of the binder resin can be 5～200 mgKOH/g. (b) The thermosetting resin is, for example, a multifunctional epoxy resin.

(c) The flame retardant is an organophosphorus compound (spirocyclic diphosphonate compound) represented by the following general formula. [化1]

In the formula, R ² and R ⁵ are each independently an optionally substituted phenyl group, an optionally substituted naphthyl group, or an optionally substituted anthryl group. R ¹ , R ³ , R ⁴ and R ⁶ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a phenyl group which may have a substituent, a naphthyl group which may have a substituent, or an anthryl group which may have a substituent.

In addition to the above-mentioned (a) component, (b) component and (c) component, the resin composition may also contain (d) a compound having an ethylenically unsaturated group (photocurable compound), and (e) a photopolymerization initiator , (F) Colorants, etc. The content of the component (c) in the resin composition may be about 10 to 30 parts by weight relative to 100 parts by weight of the total solid content.

The coating film (insulating film) is formed by applying the above-mentioned resin composition on a substrate and drying the solvent as necessary. The cured film is obtained by photocuring and/or thermal curing of the insulating film. For example, the above-mentioned resin composition is coated on the surface of a printed wiring board to form a coating film, at least a part of the surface of the coating film is irradiated with active light for photocuring, and development with alkali or the like is carried out if necessary, and then the light The cured coating film is heated and thermally cured, thereby forming a printed wiring board with a cured film. The printed wiring board may be a flexible printed wiring board using a flexible film substrate such as a polyimide film. [Effects of Invention]

The cured film formed from the above resin composition has excellent flame retardancy, is difficult to produce abnormalities such as flame retardant bleeding, and has excellent flexibility.

The resin composition of the present invention includes (a) a binder resin, (b) a thermosetting resin, and (c) an organophosphorus compound. Due to the thermosetting resin, the resin composition has thermosetting properties. (a) The binder resin may be reactive with thermosetting resin.

(a) The binder resin may have a photocurable functional group such as an ethylenically unsaturated group. By making the resin composition contain a binder resin having photocuring, the resin composition has photocuring properties (photosensitive) in addition to thermosetting properties. The resin composition may further contain (d) a compound having an ethylenically unsaturated group (photocurable compound). The resin composition may further contain (e) a photopolymerization initiator.

The resin composition may further contain (f) a coloring agent. By containing a coloring agent, the insulating film obtained from the resin composition can be arbitrarily colored.

＜(a) Adhesive resin＞ The binder resin is a polymer having solubility in organic solvents and having a weight average molecular weight of 1,000 or more and 1,000,000 or less in terms of polyethylene glycol. The weight average molecular weight of the binder resin is more preferably 2,000 to 200,000, still more preferably 3,000 to 100,000, and particularly preferably 4,000 to 50,000. If the weight average molecular weight of the binder resin is within the above range, it is easy to obtain a cured film excellent in heat resistance and flexibility.

The binder resin is a urethane-based polymer having at least one urethane bond in the molecule. By using a urethane-based polymer as the binder resin and the following organophosphorus-based compound as the (c) flame retardant, it is possible to impart excellent flame retardancy without reducing the flexibility of the insulating cured film. The urethane-based polymer is obtained by, for example, the reaction of a diol and a diisocyanate.

The diisocyanate compound may be any of an alicyclic diisocyanate compound and an aliphatic diisocyanate compound. The diisocyanate compound may be a reactant with a compound having two or more functional groups capable of reacting with an isocyanate group, for example, may be a urethane compound having an isocyanate group at the end.

The diisocyanate compound may be any one of aromatic isocyanate, alicyclic isocyanate, aliphatic isocyanate, and alicyclic diisocyanate. The diisocyanate compound may be a reactant with a compound having two or more functional groups capable of reacting with the isocyanate group of the diisocyanate compound, for example, may be a urethane compound having an isocyanate group at the end. Among them, when an alicyclic diisocyanate or an aliphatic diisocyanate is used, the resin composition tends to be excellent in photosensitivity. As alicyclic diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, norene diisocyanate etc. are mentioned. As aliphatic diisocyanate, hexamethylene diisocyanate, trimethyl hexamethylene diisocyanate, lysine diisocyanate, etc. are mentioned.

Examples of the diol include ethylene glycol, diethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 3-methyl 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10 -Decanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol and other alkylene glycols; polyethylene glycol, polypropylene glycol, polytetramethylene glycol, 1,4- Polyoxyalkylene glycols such as random copolymers of butanediol and neopentyl glycol; polyester diols obtained by reacting polyhydric alcohols with polybasic acids; polycarbonate diols with a carbonate skeleton; γ- Polycaprolactone diol obtained by ring-opening addition reaction of lactones such as butyrolactone, ε-caprolactone, δ-valerolactone; ethylene oxide adducts of bisphenol A and bisphenol A, Propylene oxide adduct of bisphenol A, hydrogenated bisphenol A, ethylene oxide adduct of hydrogenated bisphenol A, propylene oxide adduct of hydrogenated bisphenol A, etc. Diol can be used in combination of 2 or more types. Among the above, long-chain chains such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyoxyalkylene glycol, polyester diol, polycarbonate diol, and polycaprolactone diol are used. In the case of diol, the elastic modulus of the cured film decreases and the flexibility tends to increase.

The binder resin may have a carboxyl group in the molecule. By having a carboxyl group, the binder resin reacts with the following component (b), so there is a tendency for the heat resistance or chemical resistance of the cured film to improve. In addition, when used as a photosensitive resin composition, by making the binder resin have a carboxyl group, the solubility to an alkaline developer is improved, so that a fine pattern can be formed by a short time of development. The acid value of the binder resin is preferably 5 to 200 mgKOH/g, more preferably 15 to 100 mgKOH/g. By making the binder resin have an appropriate acid value, the cross-linked structure with component (b) is formed densely, so the heat resistance, insulation reliability, and chemical resistance of the cured film can be improved.

The polymer having a carboxyl group in the molecule is obtained, for example, by using a compound having two hydroxyl groups and one carboxyl group in the molecule as the diol component for forming the urethane-based polymer. As the diol compound containing two hydroxyl groups and one carboxyl group, there may be mentioned: 2,2-bis(hydroxymethyl)propionic acid, 2,2-bis(2-hydroxyethyl)propionic acid, 2,2-bis (3-hydroxypropyl)propionic acid, 2,3-dihydroxy-2-methylpropionic acid, 2,2-bis(hydroxymethyl)butanoic acid, 2,2-bis(2-hydroxyethyl)butane Acid, 2,2-bis(3-hydroxypropyl)butanoic acid, 2,3-dihydroxybutanoic acid, 2,4-dihydroxy-3,3-dimethylbutanoic acid and 2,3-dihydroxypalm Aliphatic diols such as acids; 2,3-dihydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid Aromatic diols such as benzoic acid and 3,5-dihydroxybenzoic acid.

The binder resin may have an ethylenically unsaturated group in the molecule. Examples of ethylenically unsaturated groups include vinyl groups and (meth)acrylic groups. In addition, in this specification, "(meth)acrylic group" means acrylic or methacrylic group, and "(meth)acrylic acid group" means acrylic or methacrylic acid group.

If the binder resin has a photocurable functional group such as a (meth)acryloyl group, a photocurable film can be formed from the resin composition. In addition, when the resin composition contains the following component (d), the binder resin having a photocurable functional group also reacts with the component (d), thereby increasing the crosslinking density of the photocurable film, improving heat resistance or The tendency for chemical resistance. By increasing the photocrosslinking density, there is a tendency to suppress the elution of the flame retardant into the developer and the like.

A polymer having a (meth)acrylic acid group in the molecule can be obtained, for example, by using the following method: in addition to the diol component and diisocyanate component used to form the urethane-based polymer, A compound containing a hydroxyl group and at least one (meth)acrylic group and/or a compound containing an isocyanate group and at least one (meth)acrylic group in the molecule.

Examples of compounds having a hydroxyl group and a (meth)acrylic acid group in the molecule include: 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate Ester, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-hydroxy-1-propenoxy-3-methacryloxypropane, o-phenylphenol glycidyl ether (methyl )Acrylate, polyethylene glycol mono(meth)acrylate, pentaerythritol tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate di(meth)acrylate, 1,4-cyclohexane Alkyl dimethanol mono(meth)acrylate, 4-hydroxyphenyl (meth)acrylate, 2-(4-hydroxyphenyl)ethyl (meth)acrylate, N-methylol acrylamide, 3, 5-Dimethyl-4-hydroxybenzylacrylamide, etc. Examples of compounds having isocyanate groups and (meth)acrylic acid groups in the molecule include: 2-(meth)acrylic acid ethyl isocyanate, 1,1-(bisacrylic acid isocyanate) (Methyl)ethyl, 2-(2-methacryloxyethoxy)ethyl isocyanate and the like.

The binder resin may have two or more photocurable functional groups in one molecule. For example, in the polymerization of urethane polymers, in addition to diols and diisocyanates, compounds having one hydroxyl group and one (meth)acryloyl group in one molecule are used. If the ratio is increased, Obtained two (meth)acrylate urethanes having (meth)acrylic acid groups at both ends of the polymer chain.

From the viewpoint of improving the adhesion between the cured film formed of the resin composition and the substrate material such as polyimide film, the content of component (a) in the resin composition is relatively high relative to 100 parts by weight of the total solid content. It is preferably 10 to 80 parts by weight, more preferably 20 to 70 parts by weight, and still more preferably 30 to 60 parts by weight.

＜(b) Thermosetting resin＞ The thermosetting resin is a compound having at least one thermosetting functional group in the molecule. Examples of thermosetting resins include epoxy resins, oxetane resins, isocyanate resins, blocked isocyanate resins, bismaleimide resins, bisallyl imidimide resins, polyester resins (for example Unsaturated polyester resins, etc.), diallyl phthalate resins, silicone resins, vinyl ester resins, melamine resins, polybismaleimide resins (BT resins), cyanate ester resins (e.g. cyanide resins) CYANATE ESTER resin, etc.), urea resin, melamine resin, sulfonamide resin, aniline resin, polyurea resin, thiourethane resin, polyurethane resin, episulfide resin , Enthiol resin, benzo 㗁𠯤 resin, etc. From the viewpoint that heat resistance can be imparted to the cured film and adhesiveness to conductors such as metal foils or circuit boards can be imparted, a multifunctional epoxy resin having two or more epoxy groups per molecule is preferred.

Examples of polyfunctional epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, hydrogenated bisphenol A type epoxy resins, biphenyl type epoxy resins, Phenoxy type epoxy resin, naphthalene type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, triphenol methane type epoxy resin, dicyclopentadiene type epoxy resin, Amine type epoxy resin, etc. The epoxy resin may also be a modified epoxy resin obtained by using urethane, rubber, chelate, dimer acid, etc. As the (b) component, a commercially available epoxy resin can also be used directly.

From the viewpoint of the heat resistance and chemical resistance of the cured film, the epoxy equivalent of the epoxy resin (the mass (g) of the compound containing 1 equivalent of epoxy group) is preferably 2000 or less, more preferably 1500 or less . The weight average molecular weight of the epoxy resin is preferably about 150-2000, more preferably about 200-1500.

From the viewpoint of improving the heat resistance or chemical resistance of the cured film formed from the resin composition, the content of the component (b) in the resin composition is preferably 1 to 100 parts by weight of the total solid content. 70 parts by weight, more preferably 5-50 parts by weight, still more preferably 10-20 parts by weight.

The resin composition may also contain a curing agent and/or curing accelerator for the thermosetting resin. Examples of the curing agent include phenol resins such as phenolic novolak resins, cresol novolac resins, and naphthalene-type phenol resins; amino resins, urea resins, melamine, dicyandiamide, and the like. Examples of hardening accelerators include phosphine compounds such as triphenylphosphine; amine compounds such as tertiary amines, trimethanolamine, triethanolamine, and tetraethanolamine; 1,8-diaza-bicyclo[5,4, 0] Borate compounds such as-7-undecene tetraphenylborate; imidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-decene Monoalkylimidazole, 1-benzyl-2-methylimidazole, 2-heptadecylimidazole, 2-isopropylimidazole, 2,4-dimethylimidazole, 2-phenyl-4-methylimidazole, etc. Imidazoles; 2-methylimidazoline, 2-ethylimidazoline, 2-isopropylimidazoline, 2-phenylimidazoline, 2-undecylimidazoline, 2,4-dimethylimidazoline , 2-Phenyl-4-methylimidazoline and other imidazolines; 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-tris-tris 𠯤, 2 ,4-Diamino-6-[2'-Undecylimidazolyl-(1')]-Ethyl-s-tris, 2,4-Diamino-6[2'-ethyl-4 '-Methylimidazolyl-(1')]-Ethyl-same three 𠯤 etc. are imidazoles and so on.

＜(c) Flame retardant＞ The resin composition contains an organophosphorus compound (spirocyclic bisphosphonate compound) represented by the following general formula as a flame retardant.

[化2]

In the formula, R ² and R ⁵ are each independently an optionally substituted phenyl group, an optionally substituted naphthyl group, or an optionally substituted anthryl group. R ¹ , R ³ , R ⁴ and R ⁶ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a phenyl group which may have a substituent, a naphthyl group which may have a substituent, or an anthryl group which may have a substituent.

The above-mentioned organophosphorus-based compound can be produced, for example, by a method described in JP 2004-35480 A.

By using a urethane-based polymer as a binder resin and a spirocyclic bisphosphonate-based compound as a flame retardant, an insulating film exhibiting excellent flame retardancy can be obtained by adding a small amount of flame retardant . The flame retardant is added in a small amount, so it is possible to suppress the decrease in heat resistance or film strength accompanying the addition of the flame retardant. As a factor for the improvement of flame retardancy by the combination of the above-mentioned binder resin and flame retardant, it is thought that the thermal decomposition behavior of the polymer and the flame retardant match. For example, the free radicals generated by the thermal decomposition of the polymer are captured by the flame retardant, so the chain reaction can be stopped in the initial stage of combustion, which is a factor that contributes to the improvement of flame retardancy.

In the case of using a resin composition as a photosensitive resin composition, by using a spiro bisphosphonate-based compound as a flame retardant, the flame retardancy or adhesion of the photocured film is unlikely to change before and after alkali development. The exudation of flame retardant is also difficult to produce. As the reason for the small change in characteristics before and after alkaline development, the flame retardant is an organophosphorus compound and therefore has high compatibility with the binder resin; or the flame retardant is solid at room temperature and therefore difficult Dissolve into alkaline developer, etc.

Normally, the more the content of the flame retardant in the cured film containing the flame retardant, the more the flexibility is reduced and the bending resistance tends to deteriorate. However, the urethane polymer as the component (a) In the combination with the spirocyclic bisphosphonate flame retardant as the component (c), even if the flame retardant is added, the flexibility is difficult to decrease. Therefore, the resin composition of the present invention can also be preferably used for the formation of an insulating protective film of a flexible printed wiring board for a foldable device.

The content of component (c) in the resin composition is preferably 1 to 50 parts by weight, more preferably 5 to 40 parts by weight, and still more preferably 10 to 30 parts by weight relative to 100 parts by weight of the total solid content . Compared with inorganic phosphorus-based compounds, the above-mentioned spiro bisphosphonate-based compounds easily exhibit a flame retardant effect even in small amounts. Therefore, the content of the component (c) in the resin composition may be 20 parts by weight or less or 15 parts by weight or less. The amount of phosphorus atoms contained in the total solid content of the resin composition is preferably 0.5 to 10% by weight, more preferably 1 to 7% by weight, and still more preferably 1.5 to 5% by weight. The content of phosphorus atoms may also be 4% by weight or less or 3% by weight or less.

＜(d) Light-curing compound＞ The resin composition may also contain a photocurable compound. By containing the photocurable compound, the resin composition has photosensitivity. When (a) the binder resin has a photocurable functional group, the photocurable compound also reacts with the component (a), so the crosslinking density of the photocurable film is improved, and the heat resistance or chemical resistance is improved. tendency.

The photocurable compound has at least one photocurable functional group. The photocurable functional group is preferably an ethylenically unsaturated group. Examples of ethylenically unsaturated groups include (meth)acrylic groups and vinyl groups. (d) It is preferable that the component has 2 or more photocurable functional groups in 1 molecule.

From the viewpoint of increasing the crosslink density of the photocured film, a component having a molecular weight lower than the component (a) is used as the component (d). (d) The weight average molecular weight of the component is preferably 2,000 or less, more preferably 1,500 or less, and still more preferably less than 1,000. (d) The functional group equivalent of the component (the mass (g) of the compound containing 1 equivalent of the ethylenically unsaturated group) is preferably 1000 or less, more preferably 750 or less, and still more preferably 500 or less.

Examples of polyfunctional (meth)acrylates having two or more (meth)acrylic groups in one molecule include ethylene glycol di(meth)acrylate and diethylene glycol di(meth)acrylate , Triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol two (Meth)acrylate, polypropylene glycol di(meth)acrylate, 2-hydroxy-1-(meth)acryloxy-3-(meth)acryloxypropane, 1,4-butane Alcohol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate , Pentaerythritol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, 2,4-diethyl-1,5-pentanediol di(meth)acrylate, 2-hydroxy -1,3-bis(meth)acryloyloxypropane, 3-methyl-1,5-pentanediol di(meth)acrylate, 2,4-diethyl-1,5-pentane Alcohol di(meth)acrylate, 1,4-cyclohexanedimethanol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 4,4'-isopropylidene Diphenol bis(meth)acrylate, 2,2-bis[4-((meth)propenoxyethoxy)phenyl]propane, 2,2-bis[4-((meth)propene Oxydiethoxy)phenyl]propane, 2,2-bis[4-((meth)acryloxypolyethoxy)phenyl]propane, 2,2-hydrobis[4-( (Meth)acryloyloxypolyethoxy)phenyl)propane, 2,2-bis[4-((meth)acryloxypolypropoxy)phenyl]propane, bisphenol F EO(Ethylene Oxide, ethylene oxide) modification (n=2～50) di(meth)acrylate, bisphenol A EO modification (n=2～50) di(meth)acrylate, bisphenol S EO modification (N=2～50) di(meth)acrylate and other bifunctional (meth)acrylates; trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, triethoxylate Methylolpropane tri(meth)acrylate, propoxytrimethylolpropane tri(meth)acrylate, triisocyanurate (ethane (meth)acrylate), 1,3,5- Tri(meth)acrylic acid hexahydrotris(meth)acrylate and other trifunctional (meth)acrylates; tetramethylolmethane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, ethoxylated pentaerythritol tetra( Meth) acrylate, propoxylated pentaerythritol tetra(meth)acrylate, di-trimethylolpropane tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol poly(meth)acrylate (Meth)acrylates with four or more functions such as esters. Among the above, from the viewpoint that the solubility of the photosensitive resin composition in aqueous developing solutions such as alkaline aqueous solutions is improved and the development time can be shortened, bisphenol A EO modified (n=2-50) bis(methyl) )Acrylate.

When the resin composition contains component (d), its content is preferably 1-50 parts by weight, more preferably 5-40 parts by weight, and more preferably, relative to 100 parts by weight of the total solid content of the resin composition. Preferably it is 10-30 parts by weight.

＜(f) Photopolymerization initiator＞ When the (a) component has a photopolymerizable functional group and/or the resin composition contains the (d) component, it is preferable that the resin composition contains (e) a photopolymerization initiator. The photopolymerization initiator is a compound that absorbs light energy such as UV (Ultraviolet, ultraviolet light), activates, and initiates and promotes the reaction of radical polymerizable groups. By making the resin composition contain a photopolymerization initiator, the resin composition can be used as a photosensitive resin composition.

類、鹵代苯乙酮類、二烷氧基苯乙酮類、羥基苯乙酮類、鹵代雙咪唑類、鹵代三𠯤類等去氫型光自由基聚合起始劑。Examples of photoradical polymerization initiators include self-cleavable photoradicals such as benzoin-based compounds, acetophenones, aminoketones, oxime esters, phosphine oxide-based compounds, and azo-based compounds. Polymerization initiator; and benzophenones, benzoin ethers, benzil ketals, dibenzocycloheptanones, anthraquinones, ketones, 9-oxythio

Dehydrogenation type photo-radical polymerization initiators such as halogenated acetophenones, dialkoxy acetophenones, hydroxyacetophenones, halogenated bisimidazoles, halogenated triacetones, etc.

The content of the component (e) in the resin composition may be appropriately set. From the viewpoint of improving photosensitivity and preventing overexposure, the content of the (e) component is preferably 0.1 to 10 parts by weight, and more preferably 0.1 to 10 parts by weight relative to 100 parts by weight of the total of the (a) component and (d) component 0.3 to 5 parts by weight, more preferably 0.5 to 3 parts by weight.

＜(f) Coloring agent＞ By containing the (f) coloring agent in the resin composition, the insulating film formed from the resin composition can be arbitrarily colored. The colorant is either a dye or a pigment. As a coloring agent, a blue coloring agent, a red coloring agent, a yellow coloring agent, an orange coloring agent, a purple coloring agent, etc. are mentioned. By combining multiple coloring agents, insulating films of various colors can be formed. For example, by combining blue pigments, orange pigments, and purple pigments, black colorants can also be made.

Examples of blue colorants include CI Pigment Blue 15, 15:1, 15:2, 15:3, 15:4, 15:6, which are phthalocyanine-based, anthraquinone-based, or biswax-based pigments. , 16, 60; solvent blue 35, 63, 68, 70, 83, 87, 94, 97, 122, 136, 67, 70 as a dye system. In addition to the above, metal-substituted or unsubstituted phthalocyanine compounds can also be used as blue colorants.

Examples of orange colorants include CI Pigment Orange 5, 13, 14, 16, 17, 24, 34, 36, 38, 40, 43, 46, 49, 51, 55, 59, 61, 63, 64, 71, 73.

Examples of the purple coloring agent include: C. I. Pigment Violet 19, 23, 29, 30, 32, 36, 37, 38, 39, 40, 50; Solvent Violet 13, 36.

(f) The content of the component may be appropriately set according to the type of the coloring agent or the color of the insulating film. For example, it is about 1 to 10 parts by weight relative to 100 parts by weight of the total solid content of the resin composition, and may be 2 to About 7 parts by weight or 3 to 5 parts by weight.

＜Other ingredients＞ The resin composition may contain a solvent in addition to the above-mentioned (a) to (f) components. The solvent is not particularly limited as long as it can dissolve resin components such as the binder polymer, and it is preferably used: sulfites, formamides, acetamides, pyrrolidones, acetates, Polar organic solvents such as ethers, hexamethylphosphoramide, and γ-butyrolactone. These polar organic solvents can also be used in combination with aromatic hydrocarbons such as xylene and toluene.

The resin composition may optionally contain various additives such as a defoamer, a leveling agent, an adhesion imparting agent, a stabilizer, and a filler. Examples of defoamers and leveling agents include acrylic compounds, vinyl compounds, and silicone compounds.

＜Preparation of resin composition＞ The resin composition is prepared by mixing the above-mentioned components. The above-mentioned components can also be crushed, dispersed, or defoamed as necessary before and/or after mixing. The pulverization and dispersion may be carried out using a kneading device such as a bead mill, a ball mill, or a three-roll mill.

＜Formation of insulating film＞ By applying the resin composition (solution) on the substrate and drying the solvent as necessary, an insulating film can be formed. As the substrate, for example, a printed wiring board is used. By forming an insulating film on the metal wiring of the printed wiring board, the insulation reliability is improved. The printed wiring board may also be a flexible printed wiring board using a flexible substrate such as a polyimide film.

The coating of the resin composition on the substrate may be performed by screen printing, curtain roll, reverse roll, spray coating, spin coating using a spinner, or the like. The thickness of the coating film may be adjusted so that the thickness after drying becomes about 5-100 μm, preferably 10-100 μm. In the case of drying by heating, the drying temperature is preferably 120°C or lower, and more preferably 40 to 100°C from the viewpoint of suppressing the thermosetting reaction.

The dried coating film can be directly used as an insulating film. From the viewpoint of improving the heat resistance or chemical resistance of the insulating film, it is preferable to cure by heat curing and/or light curing. In the case of forming a thermosetting film, the (b) component may be cured by heat treatment of the coating film. When the component (a) has a carboxyl group, the component (a) reacts with the component (b) to increase the crosslinking density. From the viewpoint of making the thermal hardening sufficiently proceed and suppressing the oxidation of the metal wiring caused by heat, the hardening temperature (the highest temperature during thermal hardening) is preferably 100 to 250°C or less, more preferably 120 to 200°C, and further Preferably it is 130-180 degreeC.

In the case of forming a photocured film, the coating film may be exposed. During the exposure, the negative photomask is arranged on the coating film to irradiate active rays such as ultraviolet rays, visible rays, and electron beams to selectively harden the exposed parts. Next, by performing development by showering, covering with liquid, immersing, etc., the non-exposed part is dissolved, thereby forming a patterned cured film.

As the developer, an alkaline aqueous solution is usually used. When the component (a) has a carboxyl group and a photocurable functional group, the component (a) has alkali solubility in the unexposed coating film, and the component (a) is photocured in the coating film after exposure, so it is not It has alkali solubility again. Therefore, if a photomask is arranged for exposure and an alkaline developer is used for development, the unexposed part is dissolved in the developer, and thus a patterned cured film is formed. As described above, the spirocyclic bisphosphonate flame retardant of the component (c) is difficult to dissolve into the alkaline developer, and therefore, even if the alkaline development is performed, the characteristics such as flame retardancy and adhesion of the cured film can be maintained.

Examples of basic compounds of the developer include alkali metals, alkaline earth metals, ammonium ions, hydroxides, carbonates, bicarbonates, amine compounds, and the like. Specific examples of alkali compounds include sodium hydroxide, potassium hydroxide, ammonium hydroxide, sodium carbonate, potassium carbonate, ammonium carbonate, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, tetramethylammonium hydroxide, Tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetraisopropylammonium hydroxide, N-methyldiethanolamine, N-ethyldiethanolamine, N,N-dimethylethanolamine, triethanolamine, triiso Propanolamine, triisopropylamine, etc.

The developer may include methanol, ethanol, n-propanol, isopropanol, N-methyl-2-pyrrolidone and other organic solvents that are miscible with water. The alkali concentration of the developer is usually 0.01 to 20% by weight, preferably 0.02 to 10% by weight, and the temperature of the developer is usually 0 to 80°C, preferably 10 to 60°C. The pattern cured film (relief pattern) after development is preferably washed with a washing liquid such as water or an acidic aqueous solution.

The insulating film can be cured by heat after light curing. Regarding the coating film after photocuring, thermosetting functional groups such as epoxy groups of the component (b) remain unreacted and therefore have thermosetting properties. By heating, the carboxyl group of component (a) and the epoxy group of component (b) are reacted to form a network structure of the binder resin and the thermosetting resin, and the heat resistance of the cured film is improved. As described above, from the viewpoint of sufficiently progressing thermal hardening and suppressing oxidation of metal wiring caused by heat, the hardening temperature is preferably 100 to 250°C, more preferably 120 to 200°C, and still more preferably 130 to 180°C.

The cured film obtained from the resin composition has excellent heat resistance and flame retardancy, and therefore is preferably used as a surface protection material for printed circuit boards. In addition, the cured film is excellent in flexibility, so it is also preferably used as a cured film of a flexible printed circuit board with metal wiring on a flexible film such as a polyimide film. [Example]

Hereinafter, examples are shown to specifically describe the present invention, but the present invention is not limited by these examples.

[Synthesis example] In the following synthesis example, the polymerization is derived from a polymer having a carboxyl group in the molecule. The properties of the polymers obtained in Synthesis Examples 1 and 2 were evaluated by the following methods.

＜Solid component concentration＞ Measured in accordance with JIS K 5601-1-2. The drying conditions were 170°C×1 hour.

<Weight average molecular weight> It was measured by gel permeation chromatography (GPC) under the following conditions. Device used: Tosoh HLC-8220GPC equivalent column: Tosoh TSK gel Super AWM-H (6.0 mm ID×15 cm)×2 guard column: Tosoh TSK guard column Super AW-H Eluent: 30 mM LiBr＋20 mM H ₃ PO ₄ in DMF(N,N-Dimethylformamide, N,N-Dimethylformamide) Flow rate: 0.6 mL/min Column temperature: 40℃ Detection conditions: RI: polarity (+), response (0.5 sec) Sample concentration: about 5 mg/mL Molecular weight standard: PEG (Polyethylene Glycol, polyethylene glycol)

＜Acid value＞ Measured in accordance with JIS K 5601-2-1.

(Synthesis example 1) Add 1,2-bis(2-methoxyethoxy)ethane (triethylene glycol dimethyl ether) 40.00 as a polymerization solvent to a reaction vessel equipped with a stirrer, thermometer, dropping funnel, and nitrogen introduction tube g and 20.62 g (0.100 mol) of norene diisocyanate, while stirring under nitrogen flow, while heating to 80°C to dissolve. It took 1 hour to add polycarbonate diol (manufactured by Asahi Kasei Co., Ltd., trade name: PCDL T5652, weight average molecular weight 2000): 50.00 g (0.025 mol), 2,2-bis(hydroxymethyl) Butyric acid: 3.70 g (0.025 mol), and 2-hydroxyethyl methacrylate: 13.02 g (0.100 mol) dissolved in triethylene glycol dimethyl ether: 40.00 g. The solution was heated and stirred at 80°C for 5 hours to obtain a solution of a urethane polymer (a1) containing a carboxyl group in the molecule and having a methacryl group at the end. The solid content of the solution is 52%, the weight average molecular weight of the polymer is 8,600, and the acid value is 18 mgKOH/g.

(Synthesis example 2) To a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel, and a nitrogen introduction tube, 100.0 g of triethylene glycol dimethyl ether as a polymerization solvent was added, and the temperature was raised to 80°C while stirring under a nitrogen stream. 12.0 g (0.14 mol) of methacrylic acid, 28.0 g (0.16 mol) of benzyl methacrylate, 60.0 g (0.42 mol) of butyl methacrylate, which will be pre-mixed at room temperature, and used as free radical polymerization 0.5 g of azobisisobutyronitrile as the starting agent was kept at 80°C for 3 hours, and was added dropwise from the dropping funnel. After the dropwise addition, while stirring the reaction solution, the temperature was raised to 90°C, and then the temperature of the reaction solution was kept at 90°C, and stirring was continued for 2 hours to obtain a solution of acrylic polymer (a2) containing carboxyl groups in the molecule. . The solid content of the solution is 50%, the weight average molecular weight of the polymer is 48,000, and the acid value is 78 mgKOH/g.

[Preparation of resin composition] The formulated composition shown in Table 1 (unit: parts by weight) was dissolved in triethylene glycol dimethyl ether, stirred by a stirring device, and then dispersed by a three-roll mill. After that, defoaming is performed by the defoaming device to prepare a uniform solution. The amount of triethylene glycol dimethyl ether as a solvent (including the total solvent amount of the solvent contained in the polymer solution of the above synthesis example) was set to 30 parts by weight. In addition to the components shown in Table 1, 1.0 parts by weight of a photopolymerization initiator (ethyl ketone, 1-[9-ethyl-6-(2-methylbenzyl)-9H) was added to each resin composition -Carbazol-3-yl]-,1-(o-acetyloxime); "Irgacure OXE02" manufactured by BASF) and 0.1 parts by weight of butadiene-based defoamer ("Flowlen AC" manufactured by Kyoeisha Chemical -2000").

[Formation and evaluation of cured film] <Form cured film on polyimide film> On a polyimide film with a thickness of 25 μm ("Apical 25NPI" manufactured by Kaneka), screen printing to a final dry thickness The resin composition was applied to the thickness of 20 μm, dried at 80° C. for 20 minutes, and then irradiated with 100 mJ/cm ² of ultraviolet rays for exposure. Next, a 1.0 wt% sodium carbonate aqueous solution at 30°C was sprayed at a spray pressure of 1.0 kgf/mm ² for 60 seconds for development. After development, it was thoroughly washed with pure water, and then heated in an oven at 140°C for 60 minutes to form a cured film on the polyimide film (after development).

The resin composition was coated on the polyimide film in the same manner as above, and after drying and exposure, without developing, it was heated in an oven at 140°C for 60 minutes to form a cured film on the polyimide film (before development) ).

＜Flame retardancy＞ The polyimide film on which the cured film (before development and after development) was formed was used as a sample, and a flame retardancy test was performed as described below in accordance with the flame retardancy UL94 standard. Cut out the polyimide film with hardened film width 50 mm×length 200 mm, insert the marking line at the center of the length direction (125 mm), and roll it into a cylindrical shape so that the hardened film side becomes the outside. Stick tape on the overlapping part above the marking line (the part at 75 mm in the length direction) and the upper part without gaps to make a tube for flame retardancy test.

Clamp the upper part of the sample with a clamp and fix it vertically. Bring the flame of the burner close to the lower part of the sample for 3 seconds to ignite. After 3 seconds, keep the flame of the burner away, and measure the flame of the sample or disappear after a few seconds. Repeat the test 2 times for 1 sample. Set both times to keep the flame of the burner away from the sample within 10 seconds. The flame or combustion stops. The flame does not reach the mark and extinguishes itself. Set it to OK. Set any of the 2 times. The second time is not extinguished within 10 seconds or the flame burns up to the marking line as NG. Five samples were tested and evaluated based on the following criteria. A: All 5 are OK B: 1 to 4 out of 5 are OK C: All 5 are NG

＜Adhesion＞ The polyimide film on which the cured film (before and after development) was formed was used as a sample, and the adhesiveness of the cured film was evaluated in accordance with the checkerboard tape method of JIS K 5400. The tape peeling test was repeated 5 times on one sample, and the evaluation was made based on the following criteria based on the residual area rate (residual film rate) of the cured film in the sample after the test. A: No peeling is observed (the remaining area rate is 100%) B: Peeling is observed, but the remaining area rate is 95% or more C: The remaining area rate is more than 80% and less than 95 D: The remaining area rate is less than 80%

Cut the polyimide film with the cured film (after development) into a size of 5 mm×100 mm, bend it 180° so that the cured film becomes the outside, and place a load of 100 g on the bend for 3 seconds. After removing the load, observe the bent part with an optical microscope to evaluate whether there are cracks. Perform this operation until cracks appear in the cured film, and evaluate it based on the following criteria. A: No cracks are generated even if bent 10 times B: Cracks caused by bending 2 times or more and 9 times or less C: Cracks caused by bending once

＜Stickness＞ The resin composition was coated on the polyimide film in the same manner as above, and dried at 80°C for 20 minutes to produce a polyimide film on which a coating film (B-stage film) was formed. The two films were superimposed so that the coating films were in contact with each other, and the state at the time of peeling was observed, and the evaluation was performed based on the following criteria. A: No adhesion of the coating films to each other, and no traces of adhesion remain on the coating films B: Traces remain after the coating films are attached and peeled, or the coating films are completely attached and cannot be peeled off

＜Exudation＞ The copper foil of a flexible copper laminate laminated board formed by bonding a polyimide film with a thickness of 25 μm ("Apical 25NPI" manufactured by Kaneka) and an electrolytic copper foil with a thickness of 12 μm using a polyimide-based adhesive Etched into a comb-shaped pattern with line width/space width=100 μm/100 μm, immersed in a 10 vol% sulfuric acid aqueous solution for 1 minute for surface treatment of the copper foil, and then washed with pure water to produce a flexible printed wiring board . On the wiring forming surface of the flexible printed wiring board, the resin composition was applied by screen printing to a final dry thickness of 20 μm, and dried, exposed, developed, washed, and heated in the same manner as above to obtain Flexible printed wiring board with hardened film. Connect the wiring terminal of the sample to the power supply, and apply a direct current of 100 V in an environmental testing machine at 85℃ and 85%RH (Relative Humidity) for 1000 hours. Observe the sample visually. The benchmark is evaluated. A: No abnormalities such as bulging or exudation were observed on the surface of the test piece and the copper wiring B: Abnormalities such as bulging and oozing are observed on the surface of the test piece and/or copper wiring

[evaluation result] Table 1 shows the composition (components and percentage of P atom content relative to the total amount of solid components) of the resin compositions of the examples and comparative examples and the evaluation results. In addition, the diagonal line items in Table 1 are not evaluated. The details of each ingredient are shown below.

<1> "jER828US" manufactured by Mitsubishi Chemical; bisphenol A epoxy resin (average molecular weight 370, epoxy equivalent 190) <2> "Fancryl FA-321M" manufactured by Hitachi Chemical; EO modified bisphenol A dimethacrylate (average molecular weight 804) <3> "Fireguard FCX-210" manufactured by Teijin; Spirocyclic bisphosphonate flame retardant <4> "Exolit OP-935" manufactured by Clariant; phosphinic acid metal salt flame retardant <5> "SPB-100L" manufactured by Otsuka Chemical; phosphazene flame retardant <6> "APYRAL AOH60" manufactured by Nabaltec; aluminum hydroxide flame retardant <7> "CR-733S" manufactured by Oyagi Chemical Industry; phosphate ester flame retardant <8> A black pigment made by mixing the following blue pigments, orange pigments and purple pigments in a weight ratio of 1:1:1 Blue Pigment: Pigment Blue 15:4 made by BASF Orange Pigment: Pigment Orange 43 made by Clariant Violet Pigment: Pigment Violet 19 manufactured by Clariant

[Table 1] Reference example 1 Example 1 Example 2 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Comparative example 5 Comparative example 6 Reference example 2 Comparative example 7 Comparative example 8 composition Resin composition a1 40 40 40 40 40 40 40 40 40 - - - a2 - - - - - - - - - 40 40 40 ＜1＞jER 828US 12 12 12 12 12 12 12 12 12 12 12 12 ＜2＞FA-321M twenty one twenty one twenty one twenty one twenty one twenty one twenty one twenty one twenty one twenty one twenty one twenty one Flame retardant ＜3＞FCX - 13.2 24.3 - - - - - - - 13.2 24.3 ＜4＞Exolit - - - 14.6 27.0 40.0 - - - - - - ＜5＞SPB - - - - - - 13.2 - - - - - ＜6＞APYRAL - - - - - - - 13.2 - - - - ＜7＞CR - - - - - - - - 13.2 - - - Colorant ＜8＞Black pigment 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.4 P content (wt%) - 2.2 3.6 3.7 6.0 8.9 1.9 - 1.5 - 2.2 3.6 evaluation result Flame retardant Before development C A A B A A C C C C A A After development C A A B B A C C C C A A Adhesion Before development A A A A A D B D A A After development A A B B B D B D A A Folding resistance A A A B C C A B C Stickiness A A A A A B A B A A Ooze A A A A A B A B A A

In Reference Example 1 and Reference Example 2 where no flame retardant was added, the folding resistance was good, but the flame retardancy was insufficient. In Comparative Example 4 using a phosphazene-based flame retardant, Comparative Example 5 using an aluminum hydroxide-based flame retardant, and Comparative Example 6 using a phosphate-based flame retardant, no improvement in flame retardancy was observed. In addition, in Comparative Example 4 and Comparative Example 6 using a liquid flame retardant, the viscosity deteriorated.

In Comparative Examples 1 to 3 using phosphinic acid metal salt flame retardants, the flame retardancy is poor when the amount of flame retardant used is small. If the amount of flame retardant added is increased, the bending resistance is observed The tendency to decrease sex. In addition, in these comparative examples, the flame retardancy and adhesiveness tend to decrease after alkali development. It is believed that the cause is the elution or detachment of the flame retardant caused by alkali development.

Examples 1 and 2 using spiro diphosphonate flame retardants have excellent flame retardancy. In addition, according to the comparison between Example 1 and Comparative Examples 1 to 6, it can be seen that the spirocyclic bisphosphonate flame retardant can be added in a small amount to achieve the improvement of flame retardancy. It is believed that the reason for this is that the free radical trapping mechanism of the flame retardant effectively functions for the free radicals generated at the beginning of combustion.

In Examples 1 and 2, the cured film showed high adhesiveness, and there was no decrease in adhesiveness and heat resistance after alkali development. In addition, in Examples 1 and 2, the folding resistance was as good as the reference example 1 containing no flame retardant, and there was no reduction in the folding resistance caused by the addition of the flame retardant.

In Comparative Examples 7 and 8 in which an acrylic polymer was used as a binder resin and a spiro diphosphonate flame retardant was added, the flame retardancy, adhesion, and viscosity were good as in Examples 1 and 2. However, in Comparative Examples 7 and 8, with the increase in the addition amount of the flame retardant, the folding resistance decreased.

From the above results, it can be seen that when a spirocyclic diphosphonate flame retardant is added to a resin composition containing a urethane-based binder, it can be specifically formed to have excellent flame retardancy and adhesion. , And a cured film with excellent flexibility.

Claims (14)

A resin composition comprising (a) binder resin, (b) thermosetting resin and (c) flame retardant curable resin composition; and the above (a) binder resin has urethane in the molecule The above-mentioned (c) flame retardant is an organophosphorus compound represented by the following general formula: [Chemical Formula 1]

In the formula, R ² and R ⁵ are each independently optionally substituted phenyl, optionally substituted naphthyl or optionally substituted anthryl; R ¹ , R ³ , R ⁴ and R ⁶ are each independently hydrogen Atom, C1-C4 alkyl group, optionally substituted phenyl group, optionally substituted naphthyl group or optionally substituted anthryl group. The resin composition of claim 1, wherein the (a) binder resin has a carboxyl group in the molecule. The resin composition of claim 2, wherein the acid value of the (a) binder resin is 5 to 200 mgKOH/g. The resin composition according to any one of claims 1 to 3, wherein the (a) binder resin has an ethylenically unsaturated group in the molecule. The resin composition according to any one of claims 1 to 4, which further comprises (d) a compound having an ethylenically unsaturated group. The resin composition of claim 4 or 5, which further contains (e) a photopolymerization initiator. The resin composition according to any one of claims 1 to 6, which further contains (f) a colorant. The resin composition according to any one of claims 1 to 7, wherein the above-mentioned (b) thermosetting resin is a multifunctional epoxy resin. The resin composition according to any one of claims 1 to 8, wherein the content of the flame retardant (c) above is 10 to 30 parts by weight relative to 100 parts by weight of the total solid content. A cured film comprising a cured product of the resin composition according to any one of claims 1 to 9. A printed wiring board with a hardened film provided with the hardened film of claim 10 on the printed wiring board. The printed wiring board with a cured film of claim 11, wherein the printed wiring board has flexibility. A method of manufacturing a printed wiring board with a cured film, which coats the resin composition of any one of claims 1 to 9 on the metal wiring forming surface of the printed wiring board to form a coating film, and The coating film is hardened by heating and/or exposing it. A method for manufacturing a printed wiring board with a hardened film, which coats the resin composition of any one of claims 1 to 9 on the metal wiring forming surface of the printed wiring board to form a coating film, Irradiate at least a part of the inner surface of the coating film with active light for photocuring, The development is carried out with alkali to dissolve and remove the uncured coating film, thereby forming a patterned cured film.