Carboxygroup-containing modified imide resin, resin composition, laminate, and flexible printed circuit board

Abstract

This invention provides a carboxyl group-containing modified imide resin that is useful as an adhesive for electronic components and as a material for forming coatings such as surface protective layers and insulating protective films, and exhibits excellent solution stability, elastic modulus, heat resistance, and low warping. [Solution] A carboxyl group-containing modified imide resin comprising a structure represented by the following general formula (X), having a constituent unit derived from polyol (a), a constituent unit derived from polyamine (b), and a constituent unit derived from tetracarboxylic dianhydride (c), wherein the polyamine (b) includes an aromatic diamine (b1) and a dimer amine (b2), and the imide bond concentration is 0.5 to 2.0 mmol / g. TIFF2026100789000010.tif50170

Description

[Technical Field]

[0001] The present invention relates to a carboxyl group-containing modified imide resin, a resin composition, a laminate, and a flexible printed circuit board. [Background technology]

[0002] Generally, polyimide resins are widely used as materials for forming adhesive layers, surface protective layers, and insulating protective layers of electronic components because they are highly elastic, as well as having excellent heat resistance, flexibility, and insulation properties. However, while polyimide resins have excellent heat resistance, their rigid resin structure has presented a challenge: when applied to a substrate, the substrate tends to warp significantly.

[0003] Furthermore, polyimide resins are poorly soluble in solvents, often requiring high-boiling point solvents for dissolution. Additionally, forming coatings may require high-temperature treatment above 200°C, posing challenges in terms of processability. When forming coatings such as insulating protective layers for electronic components by applying and drying resin solutions, it is desirable to be able to dry and cure at lower temperatures and in shorter times. For polyimide resins, there has been a need for improved solubility in solvents with boiling points below 200°C and improved solution stability.

[0004] To address the above-mentioned challenges, attempts have been made to improve warpage and solution stability by incorporating a highly flexible skeleton into polyimide resins. For example, a urethaneimide resin having carboxyl groups has been proposed, obtained by reacting an isocyanate-terminated polyurethane, consisting of a polycarbonate polyol and an isocyanate, with an acid anhydride and a chain extender (Patent Document 1). Furthermore, a polyimide resin having carboxyl groups in the side chains has been proposed, obtained by reacting an acid anhydride-terminated imide oligomer, obtained by reacting a tetracarboxylic dianhydride and an isocyanate, with a polyol (Patent Documents 2 and 3). In addition, an esterimide resin synthesized from a polyol, a dimer amine, and a tetracarboxylic dianhydride has been proposed (Patent Document 4). Moreover, an adhesive composition containing a polyimide resin obtained using a dimer amine, a monoamine, and a tetracarboxylic dianhydride, along with a curing agent, has been proposed (Patent Document 5). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2011-094037 [Patent Document 2] Patent No. 6882263 [Patent Document 3] Patent No. 5304954 [Patent Document 4] Patent No. 7436352 [Patent Document 5] Japanese Patent Publication No. 2023-097359 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, while the urethane-imide resin proposed in Patent Document 1 exhibited good low warping and flexibility, its high proportion of polyol-derived structural units and low imide bond concentration meant that its heat resistance was not necessarily good. Furthermore, while the polyimide resins proposed in Patent Documents 2 and 3 exhibited good low warping and flexibility, they contained structural units derived from relatively small molecular weight isocyanates, resulting in short distances between imide bonds and strong cohesive forces. Therefore, there was room for improvement in terms of solution stability.

[0007] The polyimide resins proposed in Patent Documents 4 and 5 contain many highly flexible structural units derived from dimer amine, resulting in good solution stability, flexibility, and low warpage, but their elastic modulus is not necessarily good. Furthermore, because dimer amine contains many branched structures, it is prone to oxidative degradation, leaving room for improvement in terms of long-term heat resistance. In addition, the polyimide resin proposed in Patent Document 5 has crosslinking points concentrated at the ends of the resin, making it difficult to sufficiently increase the crosslinking density of the cured product, leaving room for improvement in terms of thermal dimensional stability.

[0008] This invention has been made in view of the problems of the prior art, and its objective is to provide a carboxyl group-containing modified imide resin that is useful as an adhesive for electronic components and as a material for forming coatings such as surface protective layers and insulating protective films, and that has excellent solution stability, elastic modulus, heat resistance, and low warping. Another objective of this invention is to provide a resin composition that can form a cured product with excellent elastic modulus, thermal dimensional stability, long-term heat resistance, flexibility, and low warping. Furthermore, an objective of this invention is to provide a laminate having a cured layer formed using the above resin composition and having excellent solder heat resistance, and a flexible printed circuit board containing this laminate as a component. [Means for solving the problem]

[0009] In other words, the present invention provides the following carboxyl group-containing modified imide resin. [1] A carboxyl group-containing modified imide resin comprising a structure represented by the following general formula (X), having a constituent unit derived from a polyol (a), a constituent unit derived from a polyamine (b), and a constituent unit derived from a tetracarboxylic dianhydride (c), wherein the polyamine (b) comprises an aromatic diamine (b1) and a dimer amine (b2), and the imide bond concentration is 0.5 to 2.0 mmol / g.

[0010] TIFF2026100789000001.tif37170 (In the above general formula (X), n represents a number from 0 to 20, R1 represents an organic group obtained by removing the acid anhydride group from a tetracarboxylic dianhydride, R2 represents an organic group obtained by removing the amino group from polyamine (b), and R3 represents an organic group obtained by removing the hydroxyl group from polyol (a))

[0011] [2] The carboxyl group-containing modified imide resin according to [1], wherein the polyol (a) comprises at least one selected from the group consisting of polycarbonate diols and polyester diols. [3] The carboxyl group-containing modified imide resin according to [2], wherein the polyol (a) further contains a polyol (a1) that is liquid at 25°C, and the content of constituent units derived from the polyol (a1) is 20 to 60% by mass. [4] The carboxyl group-containing modified imide resin according to any one of [1] to [3], wherein the molar ratio of the dimer amine (b2) in the polyamine (b) is (b2) / (b) = 0.1 to 0.7. [5] The carboxyl group-containing modified imide resin according to any one of [1] to [4], wherein the aromatic diamine (b1) is a compound having an aromatic ether bond, and the molecular weight of the portion of the aromatic diamine (b1) other than the amino group is 240 to 500. [6] A carboxyl group-containing modified imide resin according to any one of [1] to [5] above, having a number average molecular weight of 10,000 to 50,000 and an acid value of 5 to 40 mgKOH / g.

[0012] Furthermore, the present invention provides the following resin compositions. [7] The carboxyl group-containing modified imide resin according to any one of [1] to [6], and an epoxy resin having two or more epoxy groups in one molecule, and a resin composition containing the same. [8] The resin composition according to [7], further containing an organic solvent having a boiling point of 200°C or lower and dissolving the carboxyl group-containing modified imide resin.

[0013] Further, according to the present invention, a laminate and a flexible printed wiring board shown below are provided. [9] A laminate having a cured layer obtained by curing the resin composition according to [7] or [8].

[10] A flexible printed wiring board including the laminate according to [9] as a component.

Advantages of the Invention

[0014] According to the present invention, it is possible to provide a carboxyl group-containing modified imide resin that is useful as an adhesive for electronic members and a material for forming coating films such as surface protective layers and insulating protective films, and has excellent solution stability, elastic modulus, heat resistance, and low warpage properties. Further, according to the present invention, it is possible to provide a resin composition capable of forming a cured product having excellent elastic modulus, thermal dimensional stability, long-term heat resistance, flexibility, and low warpage properties. Furthermore, according to the present invention, there is provided a laminate having excellent solder heat resistance and having a cured layer formed using the above resin composition, and a flexible printed wiring board including this laminate as a component.

Modes for Carrying Out the Invention

[0015] <Carboxyl Group-Containing Modified Imide Resin> The embodiments of the present invention will be described below, but the present invention is not limited to the embodiments described below. One embodiment of the carboxyl group-containing modified imide resin of the present invention (hereinafter also simply referred to as "modified imide resin") is a resin containing a structure represented by the following general formula (X), having a constituent unit derived from polyol (a), a constituent unit derived from polyamine (b), and a constituent unit derived from tetracarboxylic dianhydride (c). Polyamine (b) includes aromatic diamine (b1) and dimeramine (b2). The imide bond concentration of the carboxyl group-containing modified imide resin of this embodiment is 0.5 to 2.0 mmol / g. The modified imide resin of this embodiment may be a resin substantially composed only of the structure represented by the following general formula (X), or it may be a resin further containing structures other than the structure represented by the following general formula (X). The details of the carboxyl group-containing modified imide resin (modified imide resin) of this embodiment will be described below.

[0016] TIFF2026100789000002.tif37170 (In the above general formula (X), n represents a number from 0 to 20, R1 represents an organic group obtained by removing the acid anhydride group from a tetracarboxylic dianhydride, R2 represents an organic group obtained by removing the amino group from polyamine (b), and R3 represents an organic group obtained by removing the hydroxyl group from polyol (a))

[0017] (Polyol (a)) Polyol (a) is a compound (diol) having two hydroxyl groups in its molecule. Polycarbonate diol and polyester diol are preferred as polyol (a). Using polycarbonate diol as polyol (a) allows for the formation of cured products such as cured layers with even better heat resistance. Furthermore, using polyester diol as polyol (a) allows for the formation of cured products such as cured layers with even better low warping and flexibility.

[0018] The polyol (a) preferably contains at least one selected from the group consisting of polycarbonate diols and polyester diols. Furthermore, the polyol (a) preferably further contains polyol (a1) that is liquid at 25°C. By using polyol (a1) that is liquid at 25°C, the viscosity of the resin solution can be reduced and the solution stability of the modified imide resin solution can be further improved. It is preferable that the polyol (a) contains 30% by mass or more of polyol (a1) that is liquid at 25°C. On the other hand, if the polyol (a) contains more than 70% by mass of polyol that is solid at 25°C, compared to the case where only polyol that is liquid at 25°C is included, the heat resistance and elastic modulus are improved, and the tackiness (stickiness) when formed into a film is reduced, and handling tends to be improved.

[0019] In the modified imide resin, the content of constituent units derived from polyol (a1) that is liquid at 25°C is preferably 20 to 60% by mass, more preferably 25 to 55% by mass, and particularly preferably 30 to 50% by mass. If the content of constituent units derived from polyol (a1) that is liquid at 25°C is less than 20% by mass, the effect of improving low warpage and flexibility may be insufficient. On the other hand, if the content of constituent units derived from polyol (a1) that is liquid at 25°C is more than 60% by mass, the heat resistance and elastic modulus may decrease slightly.

[0020] As polycarbonate diols, for example, reaction products of dialkyl carbonates such as dimethyl carbonate and diol compounds having two hydroxyl groups in the molecule can be used. Commercially available polycarbonate diols can also be used. Examples of diol compounds include linear or side-chain diols having 2 to 10 carbon atoms.

[0021] Examples of diol compounds include aliphatic diols and alicyclic diols. Examples of aliphatic diols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, and 2-methyl-1,8-octanediol. Examples of alicyclic diols include 1,4-cyclohexanedimethanol. From the viewpoint of improving the flexibility of the modified imide resin, aliphatic diols are preferred, and 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, and 3-methyl-1,5-pentanediol are more preferred.

[0022] Examples of polyester diols include those obtained by condensation polymerization of at least one of aliphatic dicarboxylic acids and aromatic dicarboxylic acids with low molecular weight glycols. Examples of aliphatic dicarboxylic acids include succinic acid, adipic acid, sebacic acid, glutaric acid, and azelaic acid. Examples of aromatic dicarboxylic acids include isophthalic acid and terephthalic acid. Examples of low molecular weight glycols include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 3-methylpentanediol, 1,6-hexamethylene glycol, neopentyl glycol, and 1,4-bishydroxymethylcyclohexane.

[0023] Other polymer polyols besides the polycarbonate diols and polyester diols mentioned above can also be used as polyol(a). Examples of other polymer polyols include polyether polyols, polylactone polyols, and dimer ols. Furthermore, short-chain polyols with a molecular weight of 300 or less can also be used in combination. The acid value of the modified imide resin can be adjusted by appropriately using short-chain polyols.

[0024] The number-average molecular weight (Mn) of polyol (a) is preferably 350 to 3,500, and more preferably 400 to 3,000. If the number-average molecular weight (Mn) of polyol (a) is less than 300, the acid value of the modified imide resin will increase, which may reduce the warpability of the modified imide resin and cured products (making them more prone to warping). On the other hand, if the number-average molecular weight (Mn) of polyol (a) is greater than 3,500, it may become difficult to increase the acid value of the modified imide resin, which may reduce the heat resistance of the cured products.

[0025] (Polyamine (b)) Polyamine (b) includes aromatic diamine (b1) and dimer amine (b2). Preferably, polyamine (b) consists substantially only of aromatic diamine (b1) and dimer amine (b2). By using polyamine (b), imide bonds can be introduced into the resin.

[0026] By introducing imide bonds derived from aromatic diamine (b1), the tensile modulus, thermal dimensional stability, and long-term heat resistance of the resulting modified imide resin and its composition can be improved. However, introducing only imide bonds derived from aromatic diamine (b1), or introducing an excessive amount of imide bonds derived from aromatic diamine (b1), tends to reduce the warp and flexure properties of the modified imide resin.

[0027] In contrast, the modified imide resin of this embodiment has improved warp flexibility, flexibility, and solution stability by further introducing imide bonds derived from dimeramine (b2) in addition to imide bonds derived from aromatic diamine (b1). Depending on the type of solvent used, if the amount of imide bonds derived from dimeramine (b2) is insufficient, the resulting imide resin solution may become cloudy. Furthermore, if only imide bonds derived from dimeramine (b2) are introduced, or if an excessive amount of imide bonds derived from dimeramine (b2) are introduced, the long-term heat resistance may be easily reduced due to oxidative degradation of the dimeramine, which contains many branched structures.

[0028] The molar ratio of dimer amine (b2) in polyamine (b) is preferably (b2) / (b) = 0.1 to 0.7, more preferably 0.15 to 0.6, and particularly preferably 0.3 to 0.5. If the molar ratio of dimer amine (b2) in polyamine (b) (=(b2) / (b)) is greater than 0.7, the elastic modulus and the long-term heat resistance of the cured product may tend to decrease. On the other hand, if the above molar ratio (=(b2) / (b)) is less than 0.1, the low warping and flexibility may tend to decrease.

[0029] Aromatic diamines (b1) include 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 3,3'-diaminodiphenyl sulfone, 1,5-diaminonaphthalene, m-phenylenediamine, p-phenylenediamine, 3,3'-dimethyl-4,4'-biphenyldiamine, benzidine, 3,3'-dimethylbenzidine, 3,3'-dimethoxybenzidine, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenylpropane, 2,4-diaminotoluene, and bis(4-amino-3-carboxyphenyl Examples include methane, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, bis[4-(4-aminophenoxy)phenyl]sulfone, bis-p-(1,1-dimethyl-5-aminopentyl)benzene, 1-isopropyl-2,4-m-phenylenediamine, m-xylylenediamine, p-xylylenediamine, 4,4'-methylenebis(2,6-xylidine), and α,α'-bis(4-aminophenyl)-1,4-diisopropylbenzene.

[0030] The aromatic diamine (b1) is preferably a compound having an aromatic ether bond. The molecular weight of the portion of aromatic diamine (b1) other than the amino group is 240 to 500. If an aromatic diamine that does not have an aromatic ether bond and whose molecular weight of the portion other than the amino group is less than 240 is used, the distance between imide bonds in the resulting modified imide resin will be shorter, and the cohesive force between imide bonds may reduce the stability of the solution. In addition, the proportion of polyol will be higher, which may reduce the heat resistance. On the other hand, if an aromatic diamine whose molecular weight of the portion other than the amino group is greater than 500 is used, the proportion of aromatic diamine in the resulting modified imide resin will be higher, which may reduce the flexibility and bendability.

[0031] Aromatic diamines (b1) having an aromatic ether bond and a molecular weight of 240-500 for the non-amino group portion include 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, and bis[4-(4-aminophenoxy)phenyl]sulfone. Using these aromatic diamines (b1) with appropriately separated aniline structures at both ends can effectively suppress turbidity or precipitate formation during synthesis.

[0032] The modified imide resin may, if necessary, further contain constituent units derived from polyamines other than aromatic diamines (b1) and dimer amines (b2) (other polyamines (diamines)). Examples of other polyamines include cyclic aliphatic diamines and linear aliphatic diamines.

[0033] Examples of cyclic aliphatic diamines include di(p-aminocyclohexyl)methane, 1,4-diaminocyclohexane, 1,3-bisaminomethylcyclohexane, isophoronediamine, and norbornanediamine. Examples of chain-like aliphatic diamines include hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, diaminopropyltetramethylene, 3-methylheptamethylenediamine, 4,4-dimethylheptamethylenediamine, 2,11-diaminododecane, 1,2-bis-3-aminopropoxyethane, 2,2-dimethylpropylenediamine, 3-methoxyhexamethylenediamine, 2,5-dimethylhexamethylenediamine, 2,5-dimethylheptamethylenediamine, 3-methylheptamethylenediamine, 5-methylnonamethylenediamine, 2,17-diaminoeicosadecane, 1,10-diamino-1,10-dimethyldecane, and 1,12-diaminooctadecane.

[0034] (Tetracarboxylic acid dianhydride (c)) Examples of tetracarboxylic dianhydrides (c) (hereinafter also simply referred to as "acid anhydrides (c)") include trimellitic anhydride ester of ethylene glycol, 4,4'-(4,4'-isopropylidene diphenoxy)diphthalic anhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 3,4'-oxydiphthalic anhydride, and 4,4'-oxydiphthalic acid Examples include anhydrides, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, ethylene glycol bis(anhydrotrimellitate), p-phenylene bis(trimellitate anhydride), cyclobutanetetracarboxylic dianhydride, methylcyclobutanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, ethanetetracarboxylic dianhydride, and 3,3',4,4'-bicyclohexyltetracarboxylic dianhydride.

[0035] From the viewpoint of heat resistance and other factors, the acid anhydride (c) is preferably an ester of trimellitic anhydride and ethylene glycol, 4,4'-(4,4'-isopropylidene diphenoxy)diphthalic anhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, and 4,4'-oxydiphthalic anhydride.

[0036] (Polyisocyanate) The modified imide resin of this embodiment may further have constituent units having urethane bonds derived from polyisocyanate. That is, the modified imide resin of this embodiment preferably includes a structure represented by the following general formula (Y), and may be substantially composed only of the structure represented by the following general formula (Y). Having constituent units with urethane bonds (urethane modification) can improve compatibility with epoxy resins. In addition, by extending the urethane with polyisocyanate, it becomes easier to adjust the molecular weight to an arbitrary value. The polyisocyanate is preferably a diisocyanate having two isocyanate groups in its molecule. Examples of diisocyanates include aromatic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates.

[0037] TIFF2026100789000003.tif31170 (In the above general formula (Y), n represents a number from 0 to 20, m represents a number from 1 to 5, R1 represents an organic group obtained by removing the acid anhydride group from a tetracarboxylic dianhydride, R2 represents an organic group obtained by removing the amino group from a polyamine (b), R3 represents an organic group obtained by removing the hydroxyl group from a polyol (a), and R4 represents an organic group obtained by removing the isocyanate group from a polyisocyanate.)

[0038] Examples of aromatic diisocyanates include tolylene diisocyanate, 4-methoxy-1,3-phenylenediisocyanate, 4-isopropyl-1,3-phenylenediisocyanate, 4-chlor-1,3-phenylenediisocyanate, 4-butoxy-1,3-phenylenediisocyanate, 2,4-diisocyanate diphenyl ether, diphenylmethane diisocyanate, juliene diisocyanate, xylylene diisocyanate, 1,5-naphthalene diisocyanate, benzidine diisocyanate, o-nitrobenzidine diisocyanate, and 4,4'-diisocyanate dibenzyl.

[0039] Examples of aliphatic diisocyanates include methylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,5-pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate, and 1,10-decamethylene diisocyanate.

[0040] Examples of alicyclic diisocyanates include 1,4-cyclohexylene diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), 1,5-tetrahydronaphthalene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, and hydrogenated xylylene diisocyanate.

[0041] From the viewpoint of reactivity and other factors, polyisocyanates such as diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), isophorone diisocyanate (IPDI), 1,6-hexamethylene diisocyanate (HDI), 1,5-pentamethylene diisocyanate (PDI), and hydrogenated diphenylmethane diisocyanate (HMDI) are preferred.

[0042] (Carboxyloid-containing modified imide resin) The modified imide resin of this embodiment has constituent units derived from a polyamine (b) containing an aromatic diamine (b1) and a dimeramine (b2), and therefore exhibits excellent elastic modulus, low warpage, and solution stability, as well as forming a cured product with excellent elastic modulus, flexibility, and long-term heat resistance. Furthermore, because the modified imide resin of this embodiment has carboxyl groups in the side chains of the polymer chain that serve as reaction sites with epoxy groups, the crosslinking density of the cured product obtained by curing with epoxy resin is higher compared to imide resins that have crosslinking sites such as carboxyl groups or acid anhydride groups at the ends of the polymer chain, and it is possible to form a cured product such as a cured layer with better thermal dimensional stability.

[0043] In the modified imide resin, the imide bond concentration (imide bond concentration derived from polyamine(b)) is 0.5 to 2.0 mmol / g, preferably 0.7 to 1.8 mmol / g, and more preferably 0.8 to 1.7 mmol / g. If the imide bond concentration is less than 0.5 mmol / g, the heat resistance and elastic modulus may decrease. On the other hand, if the imide bond concentration is greater than 2.0 mmol / g, the solution stability and low warping may decrease.

[0044] In this specification, "imide bond concentration" refers to the amount of imide bonds (mmol) per gram of modified imide resin. Furthermore, in this specification, "imide bond" refers to a bond derived from the reaction between the acid anhydride and polyamine (b), and does not include a bond derived from the reaction between the acid anhydride and isocyanate. The imide bond concentration of the modified imide resin can be controlled, for example, by adjusting the amount (mol) of polyamine (b) and the amount (g) of solids in the preparation containing polyol (a) and tetracarboxylic dianhydride (c). The theoretical value of the imide bond concentration of the modified imide resin can be calculated from the following formula (A). Imide bond concentration (theoretical value) of modified imide resin =A1×N1×1,000 / C1···(A) A1: Amount of polyamine (b) (mol) N1: Number of amino groups in polyamine (b) C1: Solid content of the prepared food (g)

[0045] When the modified imide resin contains a structure represented by general formula (Y), the urethane bond concentration in the modified imide resin is preferably 1.0 mmol / g or less, and more preferably 0.5 mmol / g or less. If the urethane bond concentration in the modified imide resin exceeds 1.0 mmol / g, the heat resistance may tend to decrease.

[0046] "Urethane bond concentration" refers to the amount of urethane bonds (mmol) per gram of modified imide resin. The urethane bond concentration of modified imide resin can be controlled, for example, by adjusting the amount (mol) of polyisocyanate and the amount (g) of solids in the preparation containing polyol (a) and tetracarboxylic dianhydride (c). The theoretical value of the urethane bond concentration of modified imide resin can be calculated using the following formula (B). Urethane bond concentration of modified imide resin (theoretical value) =A2 × N2 × 1,000 / C2 ···(B) A2: Amount of polyisocyanate (mol) N2: Number of isocyanate groups in polyisocyanate C2: Amount of solids added (g)

[0047] The number-average molecular weight (Mn) of the modified imide resin is preferably 10,000 to 50,000, and more preferably 12,000 to 45,000. If the number-average molecular weight of the modified imide resin is less than 10,000, the film-forming ability may be slightly reduced, and the heat resistance of the cured product, such as the formed cured layer, may decrease. On the other hand, if the number-average molecular weight of the modified imide resin is greater than 50,000, the solubility in organic solvents may decrease.

[0048] In this specification, the "number-average molecular weight (Mn)" of a resin refers to the polystyrene-converted value measured by gel permeation chromatography (GPC). GPC can be measured, for example, using the following apparatus and conditions.

[0049] (1) Equipment: Product name "HLC-8020" (manufactured by Tosoh Corporation) (2) Column: Product names "TSKgel G2000HXL", "G3000HXL", "G4000GXL" (manufactured by Tosoh Corporation) (3) Solvent: THF (4)Flow rate: 1.0mL / min (5) Sample concentration: 2 g / L (6) Injection volume: 100μL (7) Temperature: 40℃ (8) Detector: Model number "RI-8020" (manufactured by Tosoh Corporation) (9) Standard material: TSK standard polystyrene (manufactured by Tosoh Corporation)

[0050] The acid value of the modified imide resin is preferably 5 to 40 mgKOH / g. When the acid value of the modified imide resin is 5 mgKOH / g or higher, the crosslinking density of the cured product (crosslinked product) formed by reaction with a curing agent such as epoxy resin becomes higher, further improving the heat resistance and thermal dimensional stability of the cured product. Furthermore, when the acid value of the modified imide resin is 40 mgKOH / g or lower, it is possible to suppress the excessive increase in the crosslinking density of the cured product (crosslinked product) formed by reaction with a curing agent such as epoxy resin. This makes it possible to suppress the generation of strain, further improving the low warping and flexibility of the cured product. Moreover, when the acid value of the modified imide resin is 10 to 35 mgKOH / g, it is even more preferable because it is easier to adjust the crosslinking density of the cured product (crosslinked product) to an appropriate range. Among these, when the acid value of the modified imide resin is 15 to 25 mgKOH / g, it is particularly preferable because it is easier to achieve an optimal crosslinking density.

[0051] The acid value (measured value) of modified imide resin can be measured using a solution prepared by dissolving the modified imide resin in an organic solvent such as methyl ethyl ketone (MEK) as a sample, according to the method compliant with JIS K1557-5:2007.

[0052] (Method for producing carboxyl group-containing modified imide resin) Modified imide resins can be produced, for example, by a manufacturing method comprising the following steps (1) and (2). Steps (1) and (2) may be performed simultaneously. Step (2) may further include reacting polyisocyanate with hydroxyl groups present at the ends of the obtained modified imide resin to introduce urethane bonds. Step (1): A step to obtain an imide oligomer having an acid anhydride terminus by reacting a tetracarboxylic dianhydride (c) with a polyamine (b). Step (2): A step in which the imide oligomer having an acid anhydride end obtained in step (1) is reacted with polyol (a) to obtain a carboxyl group-containing modified imide resin.

[0053] An example of a specific procedure for producing the modified imide resin of this embodiment is shown below. First, polyamine (b), tetracarboxylic dianhydride (c), and an organic solvent are mixed and reacted at 130-160°C for about 1-7 hours with stirring to obtain an imide oligomer having acid anhydride groups at its ends. Next, polyol (a) is added so that the molar ratio of acid anhydride groups to hydroxyl groups (= acid anhydride groups / hydroxyl groups) is approximately 0.5-1.0 (0.7-1.0 is preferable if urethane modification is not performed; 0.5-0.7 is preferable if urethane modification is performed), and the mixture is reacted at 50-150°C for about 1-12 hours. After that, the mixture is diluted with an organic solvent as needed and cooled to obtain the desired carboxyl group-containing modified imide resin in resin solution form. Note that the molar ratio of acid anhydride groups to hydroxyl groups (= acid anhydride groups / hydroxyl groups) affects the acid value of the obtained carboxyl group-containing modified imide resin. For example, if the acid anhydride group / hydroxyl group (molar ratio) is less than 0.5 or greater than 1.0, the molecular weight of the resulting carboxyl group-containing modified imide resin may not be sufficiently increased, and its flexibility may decrease.

[0054] As the organic solvent, it is preferable to use an organic solvent that does not substantially react with any of the polyols (a), polyamines (b), and tetracarboxylic dianhydrides (c). In particular, it is preferable to use an organic solvent with a boiling point of 200°C or lower. By reacting and diluting with an organic solvent with a boiling point of 200°C or lower, the resulting resin solution can be used directly as a paint or composition, and can be dried or cured at low temperatures and in a short time.

[0055] Examples of organic solvents with a boiling point of 200°C or lower include toluene, cyclohexane, methylcyclohexane, ethylene glycol diethyl ether, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, methyl methoxypropionate, ethyl methoxypropionate, ethyl acetate, n-butyl acetate, isoamyl acetate, acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, dimethyl carbonate, tetrahydrofuran, and dioxane. Among these, toluene, methyl ethyl ketone, dimethyl carbonate, cyclopentanone, and cyclohexanone are preferred from the viewpoint of solubility and ease of drying of the modified imide resin, and toluene, methyl ethyl ketone, cyclohexanone, and dimethyl carbonate are more preferred.

[0056] <Resin composition> One embodiment of the resin composition of the present invention contains the aforementioned carboxyl group-containing modified imide resin and an epoxy resin having two or more epoxy groups in one molecule. That is, by reacting the aforementioned modified imide resin with an epoxy resin acting as a curing agent and curing it, a cured product such as a cured layer with excellent elastic modulus, thermal dimensional stability, long-term heat resistance, flexibility, and low warping can be formed.

[0057] The epoxy resin used as a curing agent has two or more epoxy groups in one molecule. Examples of such epoxy resins include bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, bisphenol F type epoxy resin, brominated bisphenol A type epoxy resin, phenol novolac type epoxy resin, o-cresol novolac type epoxy resin, flexible epoxy resin, epoxidized polybutadiene, amine type epoxy resin, heterocyclic epoxy resin, alicyclic epoxy resin, bisphenol S type epoxy resin, dicyclopentadiene type epoxy resin, triglycidyl isocyanurate, bixylenol type epoxy resin, and compounds having glycidyl groups.

[0058] The epoxy equivalent of the epoxy resin is preferably 100 to 10,000 g / eq, and more preferably 100 to 600 g / eq, from the viewpoint of the mechanical strength, flexibility, and heat resistance of the cured product formed.

[0059] The number-average molecular weight (Mn) of the epoxy resin is preferably 100 to 100,000, and more preferably 300 to 70,000, from the viewpoint of compatibility with the modified imide resin to be reacted with.

[0060] By adjusting the molar ratio of epoxy groups in the epoxy resin to carboxyl groups in the modified imide resin, a cured product with desired properties can be obtained. For example, it is preferable to react the epoxy resin and the modified imide resin in amounts such that the molar ratio of epoxy groups to carboxyl groups is 10 / 1 to 1 / 2. If the molar ratio is outside this range, the crosslinking properties tend to decrease, and the thermal dimensional stability of the resulting cured product may be slightly reduced.

[0061] In the resin composition, the epoxy resin content is preferably 5 to 200 parts by mass, and more preferably 10 to 100 parts by mass, per 100 parts by mass of modified imide resin (solids). A epoxy resin content of 5 parts by mass or more per 100 parts by mass of modified imide resin results in better crosslinking properties. Furthermore, a epoxy resin content of 200 parts by mass or less per 100 parts by mass of modified imide resin reduces the likelihood of decreased crosslinking properties, thereby further improving the heat resistance of the resulting cured product.

[0062] The resin composition can be prepared by mixing an epoxy resin and the aforementioned modified imide resin in a desired ratio. During preparation, the mixture may be mixed in the presence of the aforementioned organic solvent, or the epoxy resin may be added to a solution of the modified imide resin and then mixed. That is, the resin composition of this embodiment may further contain an organic solvent. By using an organic solvent, it can be used as a paint composition. When used as a paint composition, it can be dried and cured at low temperatures and used as an adhesive with excellent properties such as heat resistance and adhesion. Such a paint composition is useful, for example, as an adhesive for electronic components or as a paint composition for forming insulating protective films. Furthermore, the paint composition can be used in applications such as solder resists, electromagnetic shielding films, and paints, as well as as an adhesive for flexible printed circuit boards (substrates), conductive adhesives, and structural material adhesives.

[0063] The organic solvent is preferably one that can dissolve both epoxy resin and modified imide resin. When considering its use as a paint composition, it is preferable to use an organic solvent with a boiling point of 200°C or lower, and even more preferable to use a non-nitrogen-based organic solvent with a boiling point of 200°C or lower. By using an organic solvent with a boiling point of 200°C or lower, drying and curing can be carried out under lower temperature conditions.

[0064] As the organic solvent, the same organic solvents that can be used when producing modified imide resins can be used as described above. Specifically, toluene, cyclohexane, methylcyclohexane, ethylene glycol diethyl ether, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, methyl methoxypropionate, ethyl methoxypropionate, ethyl acetate, n-butyl acetate, isoamyl acetate, acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, and dimethyl carbonate can be used. Among these, toluene, methyl ethyl ketone, cyclohexanone, and dimethyl carbonate are preferred from the viewpoint of solubility of epoxy resins and modified imide resins, and drying efficiency when used as a paint composition.

[0065] The resin composition may optionally contain other components besides the modified imide resin, epoxy resin, and organic solvent mentioned above. Examples of other components include curing accelerators, isocyanate crosslinking agents, thermoplastic polymers, tackifying resins, pigments, antioxidants, UV absorbers, surfactants, and fillers.

[0066] The resin composition of this embodiment can be cured, for example, by applying it to a desired substrate and then holding it at a temperature of preferably 40 to 200°C, and more preferably 130 to 180°C.

[0067] <Laminates and Flexible Printed Circuit Boards> One embodiment of the laminate of the present invention has a cured layer obtained by curing the aforementioned resin composition. Another embodiment of the flexible printed circuit board of the present invention includes this laminate as a component.

[0068] The aforementioned resin compositions containing organic solvents can be used as paint compositions. For example, the paint composition can be applied to a release film by methods such as screen printing, spraying, roll coating, electrostatic coating, and curtain coating to form a coating film with a thickness of 5 to 80 μm. The organic solvent can then be removed by holding the film at 0 to 180°C for 3 to 10 minutes, and the coating film can be dried. This yields an adhesive film, which is a dried film. The drying of the coating film may be done in air or in an inert atmosphere. Furthermore, to adjust the fluidity during heat bonding, the film may be heat-treated after drying to react a portion of the modified imide resin with the curing agent. This state before heat bonding is generally called the B stage.

[0069] The laminate of this embodiment is suitable as a component of a flexible printed circuit board (substrate) (FPC). Among the constituent layers of the FPC, examples of layers formed by the aforementioned resin composition (paint composition (adhesive)) and laminate include CL (coverlay) film, adhesive film, and three-layer copper-clad laminate.

[0070] Since CL films and adhesive films are generally wound, stored, cut, and die-cut in their B-stage state, they need to be flexible in that state. Furthermore, after heat-pressing the B-stage film with the adherend, a cured layer is formed by heat-curing treatment.

[0071] CL film is composed of, for example, an "insulating plastic film / adhesive layer" or an "insulating plastic film / adhesive layer / protective film". The insulating plastic film is a film with a thickness of 1 to 200 μm, formed from plastics such as polyimide, polyimide urethane, polyester, polyphenylene sulfide, polyethersulfone, polyetheretherketone, aramid, polycarbonate, and polyarylate. Multiple layers of these films may be laminated together.

[0072] The protective film is preferably a film that can be peeled off without impairing the properties of the adhesive. Examples of protective films include films made of plastics such as polyethylene, polypropylene, polyolefin, polyester, polymethylpentene, polyvinyl chloride, polyvinylidene fluoride, and polyphenylene sulfide; films coated with silicone, fluoride, and other release agents; paper laminated with these films; and paper impregnated or coated with a release resin.

[0073] The adhesive film has a structure in which a protective film is provided on at least one surface of an adhesive layer formed from a resin composition (paint composition), and is composed, for example, of "protective film / adhesive layer" or "protective film / adhesive layer / protective film". In some cases, an insulating plastic film layer is provided within the adhesive layer. The adhesive film can also be used in multilayer printed circuit boards.

[0074] A three-layer copper-clad laminate has a structure in which copper foil is bonded to at least one surface of an insulating plastic film via an adhesive layer formed by a resin composition (coating composition). As the copper foil, for example, rolled copper foil or electrolytic copper foil conventionally used in flexible printed circuit boards can be used. The resin composition (coating composition) becomes the solder resist layer, surface protection layer, interlayer insulating layer, or adhesive layer of the FPC.

[0075] The resin composition (paint composition) of this embodiment is useful as a material for constructing semiconductor elements, overcoat inks for various electronic components, solder resist inks, and interlayer insulating films, and can also be used as a paint, coating agent, and adhesive. Solder resist ink is an ink used to form a solder resist layer. The solder resist layer is a layer that forms a film over the entire surface of a circuit conductor except for the part to be soldered, and functions as a protective film that prevents solder from adhering to unnecessary parts when wiring electronic components on a printed circuit board, and also prevents the circuit from being directly exposed to air.

[0076] The surface protection layer is a layer applied to the surface of circuit components to mechanically and chemically protect the electronic components from processing and usage environments. The interlayer insulation layer (film) is a layer (film) that prevents current from flowing between layers in which fine wiring is formed within the package substrate. The adhesive layer is a layer mainly used to bond metal layers and film layers, and is used when laminating them. [Examples]

[0077] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. In the examples and comparative examples, "parts" and "%" are based on mass unless otherwise specified.

[0078] <Preparing the materials> The following materials were prepared.

[0079] (Polyol (a)) • PH-50: Product name "Ethanacol PH-50", manufactured by UBE, polyhexamethylene / pentamethylene copolymer carbonate diol, number average molecular weight 508, liquid at 25°C. • PH-100: Product name "Ethanacol PH-100", manufactured by UBE, polyhexamethylene / pentamethylene copolymer carbonate diol, number average molecular weight 984, liquid at 25°C. • PH-200: Product name "Ethanacol PH-200", manufactured by UBE, polyhexamethylene / pentamethylene copolymer carbonate diol, number average molecular weight 1,968, liquid at 25°C. • PH-300: Product name "Ethanacol PH-300", manufactured by UBE, polyhexamethylene / pentamethylene copolymer carbonate diol, number average molecular weight 2,914, liquid at 25°C. • UH-100: Product name "Ethanacol UH-100", manufactured by UBE, polyhexamethylene carbonate diol, number average molecular weight 1,000, solid at 25°C. • UH-200: Product name "Ethanacol UH-200", manufactured by UBE, polyhexamethylene carbonate diol, number average molecular weight 1,958, solid at 25°C. • P-1050: Product name "Kuraray Polyol P1050", manufactured by Kuraray Co., Ltd., 3-methyl-1,5-pentanediol / sebacic acid-based polyester diol, number average molecular weight 989, liquid at 25°C. • P-2050: Product name "Kuraray Polyol P2050", manufactured by Kuraray Co., Ltd., 3-methyl-1,5-pentanediol / sebacic acid-based polyester diol, number average molecular weight 1,941, liquid at 25°C. • 1,6-HD: 1,6-hexanediol, solid at 25°C

[0080] (Aromatic diamine (b1)) • BAPP: 2,2-bis[4-(4-aminophenoxy)phenyl]propane, molecular weight 410 (molecular weight of non-amino group portion 378) TPE-R: 1,3-bis(4-aminophenoxy)benzene, molecular weight 292 (molecular weight of the non-amino group portion 260) • ODA: 4,4'-diaminodiphenyl ether, molecular weight 200 (molecular weight of non-amino group portion 168)

[0081] (Dimer amine (b2)) • P1074: Product name "Priamine 1074", manufactured by CRODA, dimer amine, number average molecular weight 529

[0082] (Aliphatic diamines) • 1,3-BAC: 1,3-bisaminomethylcyclohexane, number-average molecular weight 142.25

[0083] (acid anhydride(c)) BPADA: 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride • BPDA: 3,3',4,4'-biphenyltetracarboxylic acid dianhydride

[0084] (Polyisocyanate) • TDI: Trilene-2,4-diisocyanate MDI: Diphenylmethane diisocyanate

[0085] (Hardening agent) • Epoxy resin A: Product name "jER828", manufactured by Mitsubishi Chemical Corporation, bisphenol A type epoxy resin, epoxy equivalent weight 184 g / eq, number average molecular weight 368

[0086] <Manufacturing of Modified Imide Resins> (Example 1) 26.0 parts (0.06 mol) of BAPP, 26.0 parts (0.05 mol) of P1074, 85.6 parts (0.16 mol) of BPADA, and 58.5 parts of cyclohexanone were placed in a separable flask equipped with a stirrer. The mixture was reacted at 150°C for 3 hours to obtain an imide oligomer having acid anhydride groups at its ends. After dilution with the addition of 97.5 parts of cyclohexanone, 100.0 parts (0.05 mol) of PH-200 and 0.5 parts (0.004 mol) of 1,6-HD were added, and the mixture was reacted at 120°C for 5 hours. Infrared absorption spectroscopy revealed an imide oligomer at 1,850 cm² derived from the free acid anhydride groups. -1 After confirming that the absorption had disappeared, 195.1 parts of cyclohexanone were added to dilute the solution, and it was cooled to room temperature to obtain a solution of modified imide resin A with a solid content of 40%. The number-average molecular weight (Mn) of modified imide resin A was 15,000, and the acid value (measured value) was 25 mgKOH / g.

[0087] (Example 9) 31.0 parts (0.08 mol) of BAPP, 31.0 parts (0.06 mol) of P1074, 115.0 parts (0.20 mol) of BPADA, and 69.6 parts of cyclohexanone were placed in a separable flask equipped with a stirrer. The mixture was reacted at 150°C for 3 hours to obtain an imide oligomer having acid anhydride groups at its ends. After dilution with the addition of 116.0 parts of cyclohexanone, 100.0 parts (0.1 mol) of PH-100 was added, and the mixture was reacted at 120°C for 5 hours. Infrared absorption spectroscopy revealed that a 1,850 cm⁻¹ ¹⁵ -1 After confirming that the absorption had disappeared, 6.3 parts (0.04 mol) of TDI was added and the mixture was reacted at 90°C for 2 hours. Infrared absorption spectroscopy revealed that the absorption of 2,270 cm⁻¹ originated from the free isocyanate group. -1 After confirming that the absorption had disappeared, 232.0 parts of cyclohexanone were added to dilute the solution, and it was cooled to room temperature to obtain a solution of modified imide resin I with urethane bonds and a solid content of 40%. The number-average molecular weight (Mn) of modified imide resin I was 25,000, and the acid value (measured value) was 25 mgKOH / g.

[0088] (Comparative Example 1) 70.0 parts (0.13 mol) of P1074, 99.6 parts (0.19 mol) of BPADA, and 66.6 parts of cyclohexanone were placed in a separable flask equipped with a stirrer. The mixture was reacted at 150°C for 3 hours to obtain an imide oligomer having acid anhydride groups at its ends. After dilution with the addition of 110.9 parts of cyclohexanone, 100.0 parts (0.10 mol) of PH-200 and 1.4 parts (0.01 mol) of 1,6-HD were added, and the mixture was reacted at 120°C for 5 hours. Infrared absorption spectroscopy revealed that a 1,850 cm⁻¹ ray originating from the free acid anhydride groups was detected. -1 After confirming that the absorption had disappeared, 221.9 parts of cyclohexanone were added to dilute the solution, and it was cooled to room temperature to obtain a 40% solids solution of modified imide resin AA. The number-average molecular weight (Mn) of modified imide resin AA was 15,000, and the acid value (measured value) was 25 mgKOH / g.

[0089] (Comparative Example 7: Reaction of acid anhydride with isocyanate) 85.7 parts (0.16 mol) of BPADA, 30.0 parts (0.12 mol) of MDI, and 50.4 parts of cyclohexanone were placed in a separable flask equipped with a stirrer. 0.1 parts of diazabicycloundecene (DBU) was added as a catalyst, and the mixture was reacted at 150°C for 8 hours to obtain an imide resin. After dilution with the addition of 84.1 parts of cyclohexanone, 92.0 parts (0.05 mol) of PH-200 were added, and the mixture was reacted at 120°C for 5 hours. However, the mixture became insoluble during the reaction, and no resin could be obtained.

[0090] (Comparative Example 8: Imide resin with crosslinking points at the terminals) In a separable flask equipped with a stirrer, 50 parts (0.09 mol) of P1074, 50 parts (0.12 mol) of BAPP, 139.2 parts (0.27 mol) of BPADA, and 154.3 parts of cyclohexanone were added and reacted at 150°C for 5 hours. The mixture was diluted with 189.2 parts of cyclohexanone and cooled to room temperature to obtain a 40% solids solution of modified imide resin HH. This modified imide resin HH is a modified imide resin having acid anhydride groups at its terminal ends. The number-average molecular weight (Mn) of the modified imide resin HH was 15,000, and the acid anhydride value (theoretical value) was 12.5 mg KOH / g.

[0091] (Examples 2-8, 11-17) Solutions of modified imide resins B-H and K-Q were obtained in the same manner as in Example 1 described above, except that the formulations (in parts) were as shown in Tables 1-1 and 1-2 (all with a solid content concentration of 40%). The physical properties of the modified imide resins are shown in Tables 1-1 and 1-2.

[0092] (Example 10) A solution of modified imide resin J was obtained in the same manner as in Example 9 described above, except that the formulation (in parts) was as shown in Table 1-2. The physical properties of the modified imide resin are shown in Table 1-2.

[0093] (Comparative Examples 2-6) Solutions of modified imide resins BB to FF were obtained in the same manner as in Comparative Example 1, except that the formulations (in parts) were as shown in Table 1-3. The physical properties of the modified imide resins are shown in Table 1-3. In Comparative Example 3 (modified imide resin CC), insolubilization occurred during the reaction. In Comparative Examples 4 and 6 (modified imide resins DD and FF), turbidity or precipitates were formed during the reaction.

[0094] <Evaluation of Modified Imide Resins> The solution stability, elastic modulus, heat resistance, and low warpage of the modified imide resins were evaluated below. The results are shown in Tables 1-1 to 1-3. Note that the elastic modulus, heat resistance, and low warpage were evaluated only for modified imide resins CC and GG, which became insoluble during synthesis, and for modified imide resins DD and FF, which produced turbidity or precipitates.

[0095] (Solution stability) The solution stability during and after synthesis was evaluated according to the following evaluation criteria. ○: No turbidity or precipitate occurred after storing the obtained solution at 25°C for one week. ×: Turbidity or precipitate occurred during synthesis.

[0096] (Elastic modulus) The solution of the modified imide resin was applied to a release paper so that the thickness after drying was 40 μm, and then dried at 150°C for 10 minutes to form a coating film (dry film). The formed coating film was cut into a size of 60 mm in length × 15 mm in width to obtain a test piece. For the obtained test piece, a tensile test was carried out at room temperature (25°C) using an autograph (trade name "AGS-J", manufactured by Shimadzu Corporation) in accordance with JIS K-7127:1999. Then, the tensile elastic modulus of the test piece was measured, and the elastic modulus was evaluated according to the following evaluation criteria. ◎: The tensile elastic modulus was 600 N / mm 2 or more. ○: The tensile elastic modulus was 180 N / mm 2 or more and less than 600 N / mm 2 . △: The tensile elastic modulus was 100 N / mm 2 or more and less than 180 N / mm 2 . ×: The tensile elastic modulus was less than 100 N / mm 2 .

[0097] (Heat resistance) The solution of the modified imide resin was applied to a release paper so that the thickness after drying was 40 μm, and then dried at 150°C for 10 minutes to form a coating film (dry film). Next, TG-DTA (trade name "TG8120", manufactured by Rigaku Corporation) was used to obtain a TG-DTA curve by heating from room temperature at 10°C / min in an atmosphere of 100 mL / min of dry air. Then, paying attention to the temperature at which the mass decreased by 10% (10% decomposition temperature), the heat resistance was evaluated according to the following evaluation criteria. ○: The 10% decomposition temperature was 335°C or higher. △: The 10% decomposition temperature was between 330°C and 335°C. ×: The 10% decomposition temperature was less than 330°C.

[0098] (Low curvature) A modified imide resin solution was applied to a 50 μm thick polyimide film so that the thickness after drying would be 20 μm. The film was then dried at 150°C for 10 minutes to form a coating (dried film). The formed coating was cut into 5 cm x 5 cm pieces, heated to 25°C, and placed on a horizontal glass plate. The average height of the warp at the four corners was measured, and the low warp resistance (resistance to warping) was evaluated according to the evaluation criteria shown below. ◎: The average height was less than 2 mm. ○: The average height was between 2mm and 4mm. △: The average height was between 4mm and 10mm. ×: The average height was between 10mm and 15mm.

[0099] TIFF2026100789000004.tif249170

[0100] TIFF2026100789000005.tif255164

[0101] TIFF2026100789000006.tif255165

[0102] <Manufacturing of resin compositions> (Examples 18-34, Comparative Examples 9-12) Resin compositions 1 to 21 were obtained by mixing the main components (modified imide resins A to Q, AA, BB, EE, HH) in a solution (solid content concentration 40%) and a curing agent to the compositions shown in Table 2.

[0103] <Evaluation of resin compositions> (modulus of elasticity) The resin composition was applied to release paper to a thickness of 40 μm after drying, and then dried at 120°C for 10 minutes to form a coating film (dried film). The formed coating film was heated at 150°C for 3 hours to heat-cur it and form a cured film. The formed cured film was cut to a size of 60 mm in length and 15 mm in width to obtain test specimens. Tensile tests were performed on the obtained test specimens using an Autograph (product name "AGS-J", manufactured by Shimadzu Corporation) in accordance with JIS K-7127:1999 under room temperature (25°C) conditions. The tensile modulus of the test specimens was then measured, and the modulus of the cured film was evaluated according to the evaluation criteria shown below. The results are shown in Table 2. ◎: Tensile modulus of elasticity is 800 N / mm 2 That was all. ○: Tensile modulus of elasticity is 280 N / mm 2 More than 800N / mm 2 It was less than [amount missing]. △: Tensile modulus of elasticity is 100 N / mm 2 More than 280N / mm 2 It was less than [amount missing]. ×: Tensile modulus of elasticity is 100 N / mm 2 It was less than [amount missing].

[0104] (thermal dimensional stability) The resin composition was applied to release paper to a thickness of 40 μm after drying, and then dried at 120°C for 10 minutes to form a coating film (dried film). The formed coating film was heated at 150°C for 3 hours to heat-cur it and obtain a test specimen (cured film). The coefficient of linear expansion (CTE, 25-300°C) of the obtained test specimens was measured under the conditions shown below, and the heat resistance of the cured film was evaluated according to the evaluation criteria shown below. The results are shown in Table 2. (1) Equipment: Product name "Thermomechanical analyzer TMA-7100E" (manufactured by Hitachi High-Tech Science Co., Ltd.) (2) Probe: Metal tensile probe (3) Load: 10mN (4) Heating rate: 5°C / min (5) Measurement temperature range: 20~300℃ (6) Sample length: 10 mm ◎: CTE was less than 200 ppm / ℃. ○: CTE was 200 ppm or higher and less than 350 ppm / ℃. △: CTE was between 350 ppm / °C and 400 ppm / °C. ×: CTE was 400 ppm / ℃ or higher.

[0105] (Long-term heat resistance) The resin composition was applied to release paper to a thickness of 40 μm after drying, and then dried at 120°C for 10 minutes to form a coating film (dried film). The formed coating film was heated at 150°C for 3 hours to heat-cur it and form a cured film. The formed cured film was cut to a size of 10 cm in length and 10 cm in width to obtain a cured film. The obtained cured film was subjected to a long-term heat resistance test by storing it in a hot air oven at 150°C in an air atmosphere for 500 hours. The cured film before and after the test were cut to a size of 60 mm in length and 15 mm in width to obtain test specimens. Tensile tests were performed on the obtained test specimens using an Autograph (product name "AGS-J", manufactured by Shimadzu Corporation) in accordance with JIS K-7127:1999 under room temperature (25°C) conditions. The breaking strength of the test specimens was measured, and the rate of change in breaking strength was calculated according to the following formula (C), and the long-term heat resistance of the cured film was evaluated according to the evaluation criteria shown below. The results are shown in Table 2. Breaking strength change rate (%) = (S2 / S1) × 100 ... (C) S1: Breaking strength of cured film before long-term heat resistance test S2: Breaking strength of cured film after long-term heat resistance test ◎: The rate of change in fracture strength was between 90% and less than 110%. ○: The rate of change in fracture strength was 110% or more but less than 135%. △: The rate of change in fracture strength was between 135% and 150%. ×: The rate of change in fracture strength was 150% or more.

[0106] (flexibility) The resin composition was applied to release paper to a thickness of 40 μm after drying, and then dried at 120°C for 10 minutes to form a coating film (dried film). The formed coating film was heated at 150°C for 3 hours to heat-cur it and form a cured film. The formed cured film was cut into pieces measuring 1.5 cm in length and 10 cm in width to obtain test specimens. The obtained test specimens were subjected to a flexibility test using an MIT testing machine under the conditions shown below, and the number of folds at which the cured film broke was recorded. The flexibility of the cured film was then evaluated according to the evaluation criteria shown below. The results are shown in Table 2. (1) Equipment: Product name "MIT type folding resistance tester" (manufactured by Yasuda Seiki Seisakusho Co., Ltd.) (2) Load: 0.98N (3) Angle: ±135° (4) Number of flexions: 175 times / min (5) Radius of curvature: 0.38mm ○: The number of folds was 12,000 or more. △: The number of folds was between 5,000 and 12,000. ×: The number of folds was less than 5,000.

[0107] (Low curvature) The resin composition was applied to a 50 μm thick polyimide film so that the thickness after drying was 20 μm, and then dried at 150°C for 10 minutes to form a coating (cured film). The formed coating was cut into 5 cm x 5 cm pieces, heated to 25°C, and then placed on a horizontal glass plate. The average height of the warp at the four corners was measured, and the low warp resistance (resistance to warping) of the cured film was evaluated according to the evaluation criteria shown below. The results are shown in Table 2. ◎: The average height was less than 2 mm. ○: The average height was between 2mm and 4mm. △: The average height was between 4mm and 10mm. ×: The average height was between 10mm and 15mm.

[0108] TIFF2026100789000007.tif158170

[0109] <Manufacturing of laminates> Resin compositions 1 to 21 obtained in Examples 18 to 34 and Comparative Examples 9 to 12 were applied to release films, respectively, so that the thickness after drying was 20 μm. The films were then heated at 150°C for 10 minutes to dry and form a coating film (dried film). The formed coating films were heat-pressed onto a polyimide film (PI) film (product name "Kapton 200H", manufactured by Toray DuPont) at 100°C using a laminating machine. A copper-clad laminate (product name "ESPANEX MC12-25-00HRM", manufactured by Nippon Steel Chemical & Material Co., Ltd.) was laminated onto the coating film so that the copper surface was in contact with it, and heat-pressed onto it at 150°C and 3 MPa for 1 hour using a hot press. Subsequently, the laminate was heat-cured at 150°C for 2 hours to obtain a laminate (PI film / adhesive layer (cured resin composition) / copper-clad laminate (copper surface)).

[0110] <Evaluation of laminates> (Solder heat resistance) The obtained laminate was cut into 20mm x 20mm pieces to prepare test specimens. The prepared test specimens were suspended in a 288°C solder bath with the PI film side facing upwards and held for a predetermined time. After holding, the test specimens were observed, and the solder heat resistance of the laminate was evaluated according to the evaluation criteria shown below. The results are shown in Table 3. Generally, if no change occurs in a 288°C solder bath for 30 seconds, the solder heat resistance is judged to be satisfactory. ○: No swelling occurred at 288℃ for 30 seconds. △: No swelling occurred at 288℃ for 20 seconds, but swelling occurred at 288℃ for 30 seconds. ×: Swelling occurred at 288℃ for 20 seconds.

[0111] TIFF2026100789000008.tif148170 [Industrial applicability]

[0112] The carboxyl group-containing modified imide resin of the present invention is useful, for example, as a material for flexible printed circuit boards.

Claims

1. The structure comprises a constituent unit derived from a polyol (a), a constituent unit derived from a polyamine (b), and a constituent unit derived from a tetracarboxylic dianhydride (c), and is represented by the following general formula (X): The polyamine (b) comprises an aromatic diamine (b1) and a dimer amine (b2). A carboxyl group-containing modified imide resin having an imide bond concentration of 0.5 to 2.0 mmol / g. (In the above general formula (X), n represents a number from 0 to 20, R １ R represents an organic group obtained by removing the acid anhydride group from a tetracarboxylic dianhydride, ２ R represents the organic group obtained by removing the amino group from polyamine (b), ３ (This indicates an organic group obtained by removing a hydroxyl group from polyol (a)).

2. The carboxyl group-containing modified imide resin according to claim 1, wherein the polyol (a) comprises at least one selected from the group consisting of polycarbonate diols and polyester diols.

3. The polyol (a) further contains polyol (a1) which is liquid at 25°C. The carboxyl group-containing modified imide resin according to claim 2, wherein the content of constituent units derived from the polyol (a1) is 20 to 60% by mass.

4. The carboxyl group-containing modified imide resin according to claim 1, wherein the molar ratio of the dimer amine (b2) in the polyamine (b) is (b2) / (b) = 0.1 to 0.

7.

5. The aromatic diamine (b1) is a compound having an aromatic ether bond, The carboxyl group-containing modified imide resin according to claim 1, wherein the molecular weight of the portion of the aromatic diamine (b1) other than the amino group is 240 to 500.

6. A carboxyl group-containing modified imide resin according to claim 1, wherein the number average molecular weight is 10,000 to 50,000 and the acid value is 5 to 40 mgKOH / g.

7. A carboxyl group-containing modified imide resin according to any one of claims 1 to 6, A resin composition containing an epoxy resin having two or more epoxy groups in one molecule.

8. The resin composition according to claim 7, further comprising an organic solvent having a boiling point of 200°C or less, for dissolving the carboxyl group-containing modified imide resin.

9. A laminate having a cured layer obtained by curing the resin composition according to claim 7.

10. A flexible printed circuit board comprising the laminate described in claim 9 as a component.

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