WO2022201985A1

WO2022201985A1 - Modified epoxy resin, manufacturing method therefor, curable resin composition, cured product thereof, coating material, and adhesive agent

Info

Publication number: WO2022201985A1
Application number: PCT/JP2022/006176
Authority: WO
Inventors: 大樹杉山; 隼人小笠原; 航深山
Original assignee: 三菱ケミカル株式会社
Priority date: 2021-03-23
Filing date: 2022-02-16
Publication date: 2022-09-29
Also published as: JPWO2022201985A1; TW202248265A

Abstract

The present invention addresses the problem of providing: a modified epoxy resin that has excellent flexibility and adhesiveness, has good reactivity to a curing agent, and is capable of exhibiting characteristics even when combined with another epoxy resin; a curable resin composition including the modified epoxy resin; and a cured product thereof.　This modified epoxy resin is represented by formula 1 and includes a structural unit (X) derived from epoxy resin and a structural unit (Y) derived from acid terminated polyester, wherein the weight average molecular weight is 3,000-50,000, the epoxy equivalent weight is 500-10,000 g/eq, and the proportion of the structural unit (Y) derived from acid terminated polyester in formula 1 is 50-90 wt%.

Description

Modified epoxy resin, method for producing the same, curable resin composition, cured product thereof, paint and adhesive

The present invention relates to a modified epoxy resin, a curable resin composition containing the same, a cured product, and a paint or adhesive containing the cured product.

Epoxy resins are used in many applications, mainly in the fields of paints, civil engineering, and electricity, due to their excellent electrical properties, adhesiveness, heat resistance, and the like. Epoxy resins used in these applications are generally used as adhesives or paints by curing with a curing agent.
In recent years, in applications such as paints, electrical and electronic materials, adhesives, CFRP, etc., various advanced functions are progressing, and the cured products containing conventionally used epoxy resins are hard and brittle. It is becoming difficult to meet the performance required in applications. In order to improve this hard and brittle property, conventionally, flexible epoxy resins have been studied.

However, many flexible epoxy resins have poor reactivity with curing agents, causing local reactions during curing, making it difficult to obtain uniform physical properties. Moreover, even flexible epoxy resins with good reactivity may not exhibit their properties when blended with other epoxy resins.

As a flexible epoxy resin, a modified epoxy resin obtained by reacting an acid-terminated polyester with a bifunctional epoxy resin is known. and then reacting the adduct with an acid-terminated polyester having a ring to obtain a flexible modified epoxy resin.

Further, in Patent Document 2, a modified epoxy equivalent having an epoxy equivalent in the range of 450 to 800 g/equivalent is obtained by reacting an acid-terminated polyester obtained from an aliphatic divalent carboxylic acid and an aliphatic dihydric alcohol with a bifunctional epoxy resin. Epoxy resins are disclosed, and in Patent Document 3, a block copolymer composed of 5 to 95% by weight of a polyester having carboxyl groups at both ends and 5 to 95% by weight of an epoxy resin is mainly used as a raw material for a heat laminating adhesive for cans. A modified epoxy resin is described as a component, and a modified epoxy resin obtained by reacting an acid-terminated polyester obtained from an aliphatic dicarboxylic acid and an aliphatic dihydric alcohol with a bifunctional aromatic epoxy resin is disclosed. there is

JP-A-50-095398 JP 2017-8155 A JP-A-5-43859

However, the modified epoxy resin described in Patent Document 1 cannot sufficiently control the purity of the acid terminal when producing the raw material acid-terminated polyester because it uses a diol component with a high boiling point. The flexibility of the modified epoxy resin obtained was insufficient.
In Patent Document 2, since a low-molecular-weight acid-terminated polyester is used, the ratio of the skeleton derived from the bifunctional epoxy resin component contained in the modified epoxy resin is increased, resulting in insufficient flexibility.
The high-molecular-weight resin described in Patent Document 3 has a high skeleton ratio derived from a bifunctional epoxy resin contained in the high-molecular-weight resin, and has insufficient flexibility.

Therefore, the present invention provides a modified epoxy resin that has excellent flexibility and adhesiveness, has good reactivity with a curing agent, and can exhibit properties even when blended with other epoxy resins, including this modified epoxy resin. An object of the present invention is to provide a curable resin composition and a cured product.

As a result of intensive studies by the present inventors in order to solve the above problems, a modified An epoxy resin having a weight average molecular weight of 3,000 to 50,000, an epoxy equivalent of 500 to 10,000 g/eq, and a structural unit (Y) derived from an acid-terminated polyester in the formula (1) having a ratio of 50 to 90. % by weight, it was found that the modified epoxy resin can solve the above problems, and the invention was completed. That is, the gist of the present invention resides in the following [1] to [10].
[1] A modified epoxy resin containing a structural unit (X) derived from an epoxy resin and a structural unit (Y) derived from an acid-terminated polyester represented by the following formula (1),
A weight average molecular weight of 3000 to 50000 and an epoxy equivalent of 500 to 10000 g / eq,
A modified epoxy resin in which the ratio of the structural unit (Y) derived from an acid-terminated polyester in the formula (1) is 50 to 90% by weight.

(In the above formula (1), n is the average number of repetitions and is a positive number of 1 to 10. X is a divalent group represented by the following formula (2), and Y is the following formula (3 ) is a divalent group represented by

(In formula (2) above, R ¹ is a hydrocarbon group having 2 to 40 carbon atoms and may have a heteroatom. p is a repeating number and is an integer of 0 to 10.)

(In the above formula (3), R ² is a hydrocarbon group having 2 to 40 carbon atoms, may have a heteroatom, and the proportion of the aliphatic hydrocarbon group in all of R ² is 50 mol% or more. R ³ is a hydrocarbon group having 2 to 30 carbon atoms and may have a heteroatom, q is a repeating number and is an integer of 1 to 50.)
[2] The modified epoxy resin according to [1], wherein the proportion of aliphatic hydrocarbon groups having 3 or less carbon atoms in the entirety of R ³ in formula (3) is 50 mol % or more.
[3] The modified epoxy resin according to [1] or [2], wherein R ¹ contains a divalent group represented by the following formula (4) and/or the following formula (5).

(In formula (4) above, R ⁴ is a single bond, or -CH ₂ -, -C(CH ₃ ) ₂ -, -CH(CH ₃ )-, -S-, -SO ₂ -, -O- , and —CO— R ⁵ is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a phenyl group; may be different.)

(In formula (5) above, R ⁶ is selected from the group consisting of a hydrogen atom and a hydrocarbon group having 1 to 20 carbon atoms, each of which may be the same or different, and part of R ⁶ is , may form a ring condensed to this benzene ring.)
[4] The modified epoxy resin according to any one of [1] to [3], wherein R ¹ is a divalent group represented by the following formula (6).

(R ⁷ in the above formula (6) is a hydrocarbon group having 1 to 10 carbon atoms. r is the number of repetitions and is an integer of 0 to 20.)
[5] The modified epoxy resin according to any one of [1] to [4], wherein the modified epoxy resin has a molecular weight distribution (Mw/Mn) of 1.5 to 20.
[6] Any one of [1] to [5] obtained by reacting an epoxy compound (A) represented by the following formula (7) with an acid-terminated polyester (B) represented by the following formula (8) A method for producing the modified epoxy resin described.

(In formula (7) above, R ¹ and p have the same meanings as in formula (2) above.)

(In formula (8) above, R ² , R ³ and q have the same meanings as in formula (3) above.)
[7] A curable resin composition comprising the modified epoxy resin according to any one of [1] to [5] and a curing agent.
[8] A cured product obtained by curing the curable resin composition according to [7].
[9] A paint comprising the cured product of [8].
[10] An adhesive comprising the cured product of [8].

According to the present invention, a modified epoxy resin that is excellent in flexibility and adhesiveness, has good reactivity with a curing agent, and can exhibit properties even when blended with other epoxy resins, and the modified epoxy resin. A curable resin composition and a cured product thereof can be provided. However, the modified epoxy resin, curable resin composition and cured product of the present invention can be applied and developed in fields such as electric/electronic materials, FRP (fiber reinforced resin), adhesives and paints.

Although the embodiments of the present invention will be described in detail below, the present invention is not limited to the following description, and can be arbitrarily modified and implemented without departing from the gist of the present invention. In this specification, when a numerical value or a physical property value is sandwiched before and after the "~", it is used to include the values before and after it. In the present invention, the term “bifunctional” and “divalent” of the compound means that it is substantially bifunctional, and trifunctional if it does not induce gelation during production of the modified epoxy resin, i.e., 5% by weight or less. It may contain the above compounds.

[Modified epoxy resin]
A modified epoxy resin (hereinafter sometimes simply referred to as a modified epoxy resin), which is one embodiment of the present invention, is represented by the formula (1), wherein a structural unit (X) derived from an epoxy resin and a structure derived from an acid-terminated polyester are A modified epoxy resin containing a unit (Y), having a weight average molecular weight of 3000 to 50000 and an epoxy equivalent of 500 to 10000 g / eq, and a structural unit derived from the acid-terminated polyester in formula (1) The proportion of (Y) is 50 to 90% by weight.

In the above formula (1), n is the average number of repetitions and is a positive number of 1-10. X is a divalent group represented by the following formula (2), and Y is a divalent group represented by the following formula (3).

In formula (2) above, R ¹ is a hydrocarbon group having 2 to 40 carbon atoms, preferably 2 to 38 carbon atoms, more preferably 2 to 35 carbon atoms, and may have a heteroatom. The hydrocarbon group includes a hydrocarbon group containing an alicyclic skeleton, an aromatic hydrocarbon group, and a chain hydrocarbon group. Hydrocarbon groups containing an alicyclic skeleton include cycloalkylene groups, alkylenebiscycloalkylene groups, alkyl-substituted cycloalkylene groups, alkylenebis(alkyl-substituted cycloalkylene) groups, and the like. The aromatic hydrocarbon group may be any hydrocarbon group containing an aromatic ring, such as an alkylenebisphenylene group, a phenylene group, a bisphenylene group, an oxybisphenylene group, a sulfonylbisphenylene group, a carbonylbisphenylene group, and Alkyl-substituted groups and the like can be mentioned. Examples of the chain hydrocarbon group include an alkylene group and an alkylene group containing an oxygen atom. Among them, aromatic hydrocarbon groups and chain hydrocarbon groups are more preferable. p is the number of repetitions and is an integer from 0 to 10;

In the above formula (3), R ² is a hydrocarbon group having 2 to 40 carbon atoms, may have a heteroatom, and the proportion of aliphatic hydrocarbon groups in all of R ² is 50 mol% or more. . R ³ is a hydrocarbon group having 2 to 30 carbon atoms and may have a heteroatom. q is the number of repetitions and is an integer of 1-50.
The hydrocarbon group for R ² is not particularly limited, but includes, for example, linear or branched aliphatic hydrocarbon groups, alicyclic hydrocarbon groups and aromatic hydrocarbon groups, aromatic hydrocarbon groups, Straight-chain aliphatic hydrocarbon groups are preferred. The number of carbon atoms in the hydrocarbon group for R ² is preferably 3-35, more preferably 3-25, even more preferably 5-20, and particularly preferably 6-15. The proportion of the aliphatic hydrocarbon groups present in all R ² is 50 mol % or more, preferably 60 mol % or more, and more preferably 80 mol % or more. As this value increases, the flexibility tends to improve when the modified epoxy resin of the present invention is cured together with the cured product.
The hydrocarbon group for R ³ is not particularly limited, but includes, for example, a linear or branched aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, an aromatic hydrocarbon group, Straight-chain aliphatic hydrocarbon groups are preferred. The proportion of aliphatic hydrocarbon groups having 3 or less carbon atoms in all of R ³ is preferably 50 mol% or more, more preferably 60 mol% or more, still more preferably 80 mol% or more, and particularly preferably 95 mol% or more. As this value increases, the flexibility tends to improve when the modified epoxy resin of the present invention is cured together with the cured product.

The modified epoxy resin of this embodiment has excellent adhesiveness, flexibility, and good reactivity with the curing agent. This effect is due to the presence of an ester bond in the molecule, the adjustment of the ratio of the structural unit Y in the modified epoxy resin to a specific amount, and the structural unit (X) and the structural unit ( It is expressed by adjusting Y) to a specific structure.

The epoxy equivalent of the modified epoxy resin is 500 to 10000 g/eq, preferably 800 g/eq or more, more preferably 1000 g/eq or more, still more preferably 1300 g/eq or more, and particularly preferably 1400 g/eq or more. The larger the epoxy equivalent, the better the flexibility, but if the epoxy equivalent is less than 500 g/eq, the distance between the cross-linking points of the cured product becomes short, and the three-dimensional network structure becomes excessively dense. It is not preferable because there is a possibility that it will become hard and brittle.

On the other hand, it is preferably 6000 g/eq or less, more preferably 5000 g/eq or less, and even more preferably 4000 g/eq or less. The smaller the epoxy equivalent, the better the adhesiveness, but if it exceeds 10,000 g/eq, the distance between the cross-linking points becomes long and a dense three-dimensional network structure cannot be formed, which may reduce the adhesive strength. I don't like it.

The weight average molecular weight (Mw) of the modified epoxy resin is 3000 to 50000, preferably 4000 or more, more preferably 5500 or more, and even more preferably 7000 or more. On the other hand, it is more preferably 40,000 or less, more preferably 25,000 or less, and particularly preferably 20,000 or less. If the weight-average molecular weight exceeds 50,000, the distance between cross-linking points becomes long and a dense three-dimensional network structure cannot be formed, which tends to reduce the adhesive strength, which is not preferable.

The lower limit of the molecular weight distribution (=weight average molecular weight (Mw)/number average molecular weight (Mn)) of the modified epoxy resin is preferably 1.5 or more, more preferably 2.0 or more. On the other hand, the upper limit is preferably 20.0 or less, more preferably 15.0 or less, even more preferably 10.0 or less. By adjusting the value of the molecular weight distribution within the above range, a modified epoxy resin can be synthesized with good reproducibility.

The weight average molecular weight (Mw) and number average molecular weight (Mn) of the epoxy resin can be measured by gel permeation chromatography (GPC method). More detailed method examples are described in the examples below.

The modified epoxy resin exhibits excellent effects when the proportion of the acid-terminated polyester-derived structural unit (Y) in the above formula (1) is within a specific range. The ratio of structural units (Y) in the modified epoxy resin is represented by the following formula.
Formula: Proportion (% by weight) of structural unit (Y) = (weight of structural unit (Y)) x 100)/weight of modified epoxy resin

The proportion of the structural unit (Y) is 50 to 90% by weight, preferably 88% by weight or less, more preferably 85% by weight or less, and even more preferably 83% by weight or less. If the ratio of the structural unit (Y) exceeds 90% by weight, the ratio of the epoxy compound (A) to the acid-terminated polyester (B) is small when producing the modified epoxy resin, so there is a risk that the reaction will not proceed uniformly. There is
On the other hand, the proportion of the structural unit (Y) is preferably 55% by weight, more preferably 60% by weight, and even more preferably 70% by weight or more. If the ratio of the structural unit (Y) is less than 50% by weight, the properties derived from the flexible polyester skeleton exhibited by the modified epoxy resin are impaired, and the properties of the epoxy compound (A) tend to be greatly reflected. Elongation tends to deteriorate.

The modified epoxy resin has the structure of formula (1) above, where n is the average number of repetitions and is a positive number of 1 to 10, preferably a positive number of 1 to 8, more preferably It is a positive number from 1 to 5.

X is a structural unit derived from a bifunctional epoxy compound, specifically a divalent group represented by formula (2). In formula (2), R ¹ is a hydrocarbon group having 2 to 40 carbon atoms and may have a heteroatom. Note that p is the number of repetitions and is an integer of 0 to 10, preferably 1 to 8, more preferably 1 to 5.

R ¹ preferably contains a divalent group represented by the following formula (4) and/or the following formula (5).

In formula (4), R ⁴ is a single bond, or —CH ₂ —, —C(CH ₃ ) ₂ —, —CH(CH ₃ )—, —S—, —SO ₂ —, —O—, and It is a divalent group selected from the group consisting of groups represented by -CO-. R ⁵ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a phenyl group, each of which may be the same or different.

In formula (5), R ⁶ is selected from the group consisting of a hydrogen atom and a hydrocarbon group having 1 to 20 carbon atoms, each of which may be the same or different, and part of R ⁶ is bonded to each other to A ring condensed to the benzene ring may be formed.

When R ¹ includes formula (4) and/or formula (5), the total content of R ¹ is preferably 50% by weight or more, more preferably 65% by weight or more, still more preferably 75% by weight or more, and particularly preferably is 85% by weight or more.

R ¹ is also preferably a divalent group represented by formula (6).

In the above formula (6), R ⁷ is a hydrocarbon group having 1 to 10 carbon atoms, preferably 2 to 8 carbon atoms, more preferably 2 to 6 carbon atoms. Specifically, the hydrocarbon group is preferably an alkylene group, a cycloalkylene group or an aromatic hydrocarbon group, more preferably an alkylene group. The alkylene group is preferably an ethylene group, a propylene group, a trimethylene group, a butanediyl group, a pentanediyl group, a hexanediyl group, a heptanediyl group or an octanediyl group, more preferably an ethylene group, a propylene group, a butanediyl group, a pentanediyl group or a hexanediyl group. An ethylene group and a propylene group are particularly preferred. r is a repetition number and is an integer from 0 to 20;

The modified epoxy resin can also be produced by reacting the epoxy compound (A) represented by formula (7) with the acid-terminated polyester (B) represented by formula (8).

In formula (7) above, R ¹ and p have the same meanings as in formula (2) above.

In formula (8) above, R ² , R ³ and q have the same meanings as in formula (3) above.

[Epoxy compound (A)]
The epoxy compound (A) represented by formula (7) is a compound having two epoxy groups in the molecule.
Examples of bifunctional epoxy compounds having two epoxy groups include bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol E diglycidyl ether, bisphenol Z diglycidyl ether, bisphenol S diglycidyl ether, and bisphenol AD diglycidyl ether. Ether, bisphenol acetophenone diglycidyl ether, bisphenol trimethylcyclohexane diglycidyl ether, bisphenol fluorenediglycidyl ether, tetramethylbisphenol A diglycidyl ether, tetramethylbisphenol F diglycidyl ether, tetra-t-butylbisphenol A diglycidyl ether, tetramethyl bisphenol diglycidyl ethers such as bisphenol S diglycidyl ether; biphenol diglycidyl ethers such as biphenol diglycidyl ether, tetramethylbiphenol diglycidyl ether, dimethylbiphenol diglycidyl ether, tetra-t-butylbiphenol diglycidyl ether; Benzenediol-based diglycidyl ethers such as hydroquinone diglycidyl ether, dihydroanthracene diglycidyl ether, methylhydroquinone diglycidyl ether, dibutyl hydroquinone diglycidyl ether, resorcinol diglycidyl ether, methylresorcinol diglycidyl ether; dihydroanthrahydroquinone diglycidyl ether, Aromatic diglycidyl ethers such as dihydroxydiphenyl ether diglycidyl ether, thiodiphenol diglycidyl ether, dihydroxynaphthalenediglycidyl ether; the bisphenol diglycidyl ethers, biphenol diglycidyl ethers, benzenediol diglycidyl ethers and aromatic diglycidyl ethers with hydrogen added to the aromatic ring of diglycidyl ethers; adipic acid, succinic acid, phthalic acid, tetrahydrophthalic acid, methylhexahydrophthalic acid, terephthalic acid, isophthalic acid Epoxy resins produced from various carboxylic acids such as orthophthalic acid, biphenyldicarboxylic acid, dimer acid, and epihalohydrin; ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, poly Propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, polytetramethylene glycol diglycidyl ether, 1,5-pentanediol diglycidyl ether, polypentamethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, polyhexamethylene glycol diglycidyl ether, 1,7-heptanediol diglycidyl ether, polyheptamethylene glycol diglycidyl ether, 1,8-octanediol diglycidyl ether, 1,10-decanediol diglycidyl ether, 2, (Poly)alkylene glycol diglycidyl ethers consisting only of a chain structure such as 2-dimethyl-1,3-propanediol diglycidyl ether; Glycidyl ethers and the like can be mentioned.

The epoxy compound (A) is not particularly limited, but from the viewpoint of being able to control adhesion, bisphenol-based diglycidyl ethers, benzenediol-based diglycidyl ethers, biphenol-based diglycidyl ethers, polyalkylene polyol-based diglycidyl ethers, Alkylene glycol diglycidyl ethers are preferably used, and polyalkylene polyol-based diglycidyl ethers and alkylene glycol diglycidyl ethers are particularly preferably used.

Although the epoxy equivalent of the epoxy compound (A) is not particularly limited, it is preferably 100 g/eq to 1200 g/eq. From the viewpoints of handling, improvement of flexibility and adhesiveness, it is more preferably 110 g/eq to 1000 g/eq, still more preferably 120 g/eq to 800 g/eq.
The properties of the epoxy compound (A) are not particularly limited, and may be solid, liquid, or semi-solid, preferably liquid or semi-solid.

The epoxy compounds (A) listed above can be used alone or in combination of multiple types. A preferred combination is a combination selected from bisphenol-based diglycidyl ethers, benzenediol-based diglycidyl ethers, biphenol-based diglycidyl ethers, polyalkylenepolyol-based diglycidyl ethers, and alkylene glycol diglycidyl ethers.

[Acid-terminated polyester (B)]
The acid-terminated polyester (B) represented by formula (8) is a carboxylic acid-terminated polyester resin produced by polycondensation of a dihydric carboxylic acid and a dihydric alcohol.
In addition, R ² in the above formula (3) corresponds to a repeating structural unit derived from a divalent carboxylic acid described later in the acid-terminated polyester (B), and R ³ is 2 in the acid-terminated polyester (B). It corresponds to a repeating unit derived from a functional alcohol, and in the above formula (3), R ² and R ³ may also be referred to as compound units for compounds from which the respective repeating units are derived.

Although the divalent carboxylic acid is not particularly limited, it includes the following. Isomers of terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid (specifically 1,4-, 1,5-, 1,6-, 1,7-, 2,5-, 2,6-, 2,7 -, 2,8-), succinic acid, sebacic acid, isodecylsuccinic acid, dodecenylsuccinic acid, maleic acid, adipic acid, furandicarboxylic acid, malonic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, undecanedioic acid , dodecanedioic acid, brassylic acid, tetradecanedioic acid, pentadecanedioic acid, thapsic acid, heptadecanedioic acid, dipropylmalonic acid, 3-ethyl-3-methylglutaric acid, 3,3-tetramethyleneglutaric acid, dimer acid, Aliphatic dicarboxylic acids such as hydrogenated dimer acid; 1,1-cyclopropanedicarboxylic acid, 1,2-cyclopropanedicarboxylic acid, 1,1-cyclobutanedicarboxylic acid, 1,2-cyclobutanedicarboxylic acid, 1,2-cyclo pentanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, decahydro-1,4-naphthalenedicarboxylic acid, 2,3 -norbornanedicarboxylic acid, 1,3-adamantanedicarboxylic acid and the like, preferably terephthalic acid, isophthalic acid, adipic acid and sebacic acid. These divalent carboxylic acids may be used alone or in combination.

As the divalent carboxylic acid, it is preferable to use an aliphatic divalent carboxylic acid from the viewpoint of increasing flexibility.
The amount of the aliphatic dicarboxylic acid used is preferably 50 mol% or more, more preferably 60 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more, and 90 mol% or more of the total divalent carboxylic acid component. It is particularly preferred for this reason.

The dihydric alcohol is not particularly limited, but includes the following. Ethylene glycol, polyethylene glycol, 1,2-propylene glycol, 1,3-propanediol, polypropylene glycol, 1,4-butanediol, polytetramethylene glycol, 1,5-pentanediol, polypentamethylene glycol, neopentyl glycol , 1,6-hexanediol, polyhexamethylene glycol, 1,7-heptanediol, polyheptamethylene glycol, 1,8-octanediol, 1,10-decanediol, 2,2-dimethyl-1,3-propane Diols consisting only of a chain structure such as diols, diols having a cyclic structure such as 1,4-cyclohexanedimethanol and isosorbide, bisphenols such as bisphenol A ethylene oxide adducts, bisphenol A propylene oxide adducts and other aliphatic Examples include diols to which alcohol is added. These dihydric alcohols may be used alone or in combination.

As the dihydric alcohol, it is preferable to use a dihydric alcohol having 3 or less carbon atoms, and it is more preferable to use ethylene glycol and 1,2-propylene glycol. Both ethylene glycol and 1,2-propylene glycol have a boiling point of 200° C. or less, and can be reacted while sufficiently distilling off unnecessary dihydric alcohol components during the reaction under reduced pressure in the production process of acid-terminated polyester. The acid terminal purity of the polyester can be increased. On the contrary, when the acid terminal purity of the acid-terminated polyester is low, that is, when it is hydroxyl-terminated, it cannot participate in the copolymerization reaction with the epoxy resin, and the terminal epoxy group purity of the resulting modified epoxy resin is lowered. As a result, the three-dimensional network structure as designed cannot be constructed during curing, and flexibility and adhesiveness tend to decrease.

The amount of the dihydric alcohol having 3 or less carbon atoms used is preferably 50 mol% or more, more preferably 55 mol% or more, more preferably 60 mol% or more, more preferably 70 mol% or more, and further preferably 80 mol% or more of the total dihydric alcohol component. Preferably, 90 mol % or more is particularly preferable for the reason described above.

The method for producing the acid-terminated polyester (B) is not particularly limited, and it can be produced by a known method. For example, a monomer mixture containing a dihydric carboxylic acid component, a dihydric alcohol component, etc. is put into a reaction vessel, heated to raise the temperature, an esterification reaction or a transesterification reaction is performed, and the water or divalent Remove the alcohol component. After that, the polycondensation reaction is continued. At this time, the pressure inside the reactor is gradually reduced, and the polycondensation is carried out while distilling off the dihydric alcohol component under a vacuum of 150 mmHg (20 kPa) or less, preferably 15 mmHg (2 kPa) or less. I do.

Catalysts used for esterification reaction, transesterification reaction and polycondensation reaction include titanium-based catalysts, calcium acetate, calcium acetate hydrate, dibutyltin oxide, tin acetate, tin disulfide, tin oxide, 2-ethylhexanetin and the like. Tin-based catalysts, zinc acetate, antimony trioxide, germanium dioxide and the like. Among these catalysts, titanium-based catalysts are preferred because of their good reactivity.

Examples of titanium-based catalysts include titanium alkoxide compounds having an alkoxy group, titanium carboxylate compounds, titanyl carboxylates, titanyl carboxylate salts, and titanium chelate compounds.
Titanium alkoxide compounds having an alkoxy group include, for example, tetramethoxytitanium, tetraethoxytitanium, tetrapropoxytitanium, tetrabutoxytitanium, tetrapentoxytitanium, tetraoctoxytitanium and the like.

Examples of titanium carboxylate compounds include titanium formate, titanium acetate, titanium propionate, titanium octanoate, titanium oxalate, titanium succinate, titanium maleate, titanium adipate, titanium sebacate, titanium hexanetricarboxylate, and isooctanetricarboxylic acid. titanium, titanium octanetetracarboxylate, titanium decanetetracarboxylate, titanium benzoate, titanium phthalate, titanium terephthalate, titanium isophthalate, titanium 1,3-naphthalenedicarboxylate, titanium 4,4-biphenyldicarboxylate, 2, Titanium 5-toluenedicarboxylate, titanium anthracene dicarboxylate, titanium trimellitate, 2,4,6-naphthalenetricarboxylate, titanium pyromellitic acid, titanium 2,3,4,6-naphthalenetetracarboxylate, and the like. . Among these titanium-based catalysts, tetrabutoxy titanium is preferred. Titanium-based catalysts may be used alone or in combination of two or more.

The reaction temperature for the esterification reaction, transesterification reaction, or polycondensation reaction is preferably 150 to 300°C. If the reaction temperature is 150°C or higher, productivity tends to be good, and if it is 300°C or lower, decomposition of the obtained acid-terminated polyester (B) can be suppressed. The lower limit of the reaction temperature is more preferably 180°C or higher, and the upper limit is more preferably 280°C or lower.

The amount of catalyst used is preferably 10 ppm to 10000 ppm with respect to the total weight of the divalent carboxylic acid component and the dihydric alcohol component from the viewpoint of ensuring polymerization reactivity. If the amount of the catalyst used is less than 10 ppm or more than 10000 ppm, the time adjustment for polycondensation cannot cope with this, resulting in a decrease in polymerization reactivity.

The lower limit of the weight average molecular weight (Mw) of the acid-terminated polyester (B) is preferably 1,000 or more, more preferably 1,500 or more, and particularly preferably 2,000 or more. On the other hand, the upper limit of the weight average molecular weight (Mw) is preferably 10,000 or less, more preferably 9,000 or less, and particularly preferably 8,000 or less. By satisfying the above upper limit and lower limit, the structural unit (Y) occupying the modified epoxy resin can be adjusted to a suitable range.

The molecular weight distribution (=weight average molecular weight (Mw)/number average molecular weight (Mn)) is preferably 1.1 or more, more preferably 1.2 or more, and more preferably 1.3 or more. , is more preferably 1.5 or more, and particularly preferably 2.0 or more from the viewpoint of raw material availability. Further, the molecular weight distribution (Mw/Mn) is preferably 10.0 or less, more preferably 5.0 or less, and 4.3 or less to form a three-dimensional network structure as designed. It is particularly preferable in terms of improving the adhesiveness.

The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the acid-terminated polyester (B) can be measured by gel permeation chromatography (GPC method), and polystyrene equivalent values are used. A specific measuring method is as described in the section of Examples below.

The properties of the acid-terminated polyester (B) at room temperature are not particularly limited, such as a vitreous solid, a crystalline solid, or a liquid, but a crystalline solid or liquid is preferable from the viewpoint of lowering the viscosity of the modified epoxy resin and increasing miscibility.

The hydroxyl value of the acid-terminated polyester (B) is not particularly limited. It is particularly preferable from the viewpoint of raw material availability. Further, the hydroxyl value of the acid-terminated polyester (B) is preferably 60 mgKOH/g or less, more preferably 50 mgKOH/g or less, more preferably 40 mgKOH/g or less, and 30 mgKOH/g or less. is particularly preferable from the viewpoint of improving adhesiveness and flexibility.

The acid value of the acid-terminated polyester (B) is not particularly limited, but the acid value is preferably 10 mgKOH/g or more, more preferably 20 mgKOH/g or more, and particularly preferably 30 mgKOH/g or more. Also, the acid value is preferably 100 mgKOH/g or less, more preferably 90 mgKOH/g or less, and even more preferably 80 mgKOH/g or less. By adjusting the content within the above range, the purity of the terminal epoxy group of the modified epoxy resin can be improved, and the adhesiveness and flexibility can be improved.

Specific methods for measuring the glass transition temperature (Tg), hydroxyl value, and acid value of the acid-terminated polyester (B) are as described in Examples below.
The acid-terminated polyester (B) may be used singly or in combination with a plurality of divalent carboxylic acids or dihydric alcohols having different types and physical properties.

In the present invention, since the acid-terminated polyester (B) contains an aliphatic skeleton, this structural unit contained in the modified epoxy resin behaves as a soft segment. Therefore, by using an epoxy compound (A) having an aromatic skeleton that behaves as a hard segment, it is possible to control the physical properties of the modified epoxy resin as a whole. On the other hand, it is possible to further improve the flexibility of the modified epoxy resin by using the epoxy compound (A) having a polyalkylene polyol-based or alkylene glycol-based skeleton that behaves as a soft segment. By appropriately blending such a modified epoxy resin with other epoxy compounds, it is possible to exhibit excellent cured physical properties.

[Modified epoxy resin]
[Batch ratio]
The charge ratio of the epoxy compound (A) and the acid-terminated polyester (B) at the time of manufacturing the modified epoxy resin is calculated from the theoretical epoxy equivalent of the modified epoxy resin to be obtained, and the lower limit of the theoretical epoxy equivalent is It should be 500 g/eq or more, preferably 800 g/eq or more, more preferably 1000 g/eq or more, more preferably 1300 g/eq or more, still more preferably 1400 g/eq or more. The reason why it is preferable is as described in the section on the modified epoxy resin.
On the other hand, the upper limit of the theoretical epoxy equivalent must be 5000 g/eq or less, preferably 4500 g/eq or less, more preferably 4000 g/eq or less. The reason why it is preferable is as described in the section on the modified epoxy resin.

[Method for producing modified epoxy resin]
The modified epoxy resin is produced by reacting the epoxy compound (A) represented by the formula (7) and the acid-terminated polyester (B) represented by the formula (8) in the presence of a catalyst at a suitable feed ratio. can get.

[Catalyst (E)]
A catalyst (E) may be used in the reaction step for producing the modified epoxy resin. The catalyst (E) is not particularly limited as long as it is usually used as a catalyst for the advance method in the production of epoxy resins.
Examples of the catalyst (E) include alkali metal compounds, organic phosphorus compounds, tertiary amines, quaternary ammonium salts, cyclic amines, imidazoles and the like.

Specific examples of alkali metal compounds include alkali metal hydroxides such as sodium hydroxide, lithium hydroxide and potassium hydroxide; alkali metal salts such as sodium carbonate, sodium bicarbonate, sodium chloride, lithium chloride and potassium chloride; alkali metal alkoxides such as methoxide and sodium ethoxide; alkali metal hydrides such as alkali metal phenoxide, sodium hydride and lithium hydride; alkali metal salts of organic acids such as sodium acetate and sodium stearate;

Specific examples of organic phosphorus compounds include triphenylphosphine, tri-o-tolylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, tri-2,4-xylylphosphine, tri-2,5- xylylphosphine, tri-3,5-xylylphosphine, tris(p-tert-butylphenyl)phosphine, tris(p-methoxyphenyl)phosphine, tris(p-tert-butoxyphenyl)phosphine, tri(pn) -octylphenyl)phosphine, tri(pn-nonylphenyl)phosphine, triallylphosphine, tributylphosphine, trimethylphosphine, tribenzylphosphine, triisobutylphosphine, tri-tert-butylphosphine, tri-n-octylphosphine, tri Cyclohexylphosphine, tri-n-propylphosphine, di-t-butylmethylphosphine, tri-n-butylphosphine, cyclohexyldi-tert-butylphosphine, diethylphenylphosphine, di-n-butylphenylphosphine, di-tert-butyl phenylphosphine, methyldiphenylphosphine, ethyldiphenylphosphine, diphenylpropylphosphine, isopropyldiphenylphosphine, cyclohexyldiphenylphosphine, tetramethylphosphonium bromide, tetramethylphosphonium iodide, tetramethylphosphonium hydroxide, trimethylcyclohexylphosphonium chloride, trimethylcyclohexylphosphonium bromide, trimethylbenzylphosphonium chloride, trimethylbenzylphosphonium bromide, tetraphenylphosphonium bromide, triphenylmethylphosphonium bromide, triphenylmethylphosphonium iodide, triphenylethylphosphonium chloride, triphenylethylphosphonium bromide, triphenylethylphosphonium iodide, triphenylbenzyl phosphonium chloride, triphenylbenzylphosphonium bromide and the like.

Specific examples of tertiary amines include triethylamine, tri-n-propylamine, tri-n-butylamine, triethanolamine, N,N-dimethylbenzylamine, and the like.

Specific examples of quaternary ammonium salts include tetramethylammonium chloride, tetramethylammonium bromide, tetramethylammonium hydroxide, triethylmethylammonium chloride, tetraethylammonium chloride, tetraethylammonium bromide, tetraethylammonium iodide, tetrapropylammonium bromide, tetrapropylammonium hydroxide, tetrabutylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium iodide, benzyltrimethylammonium chloride, benzyltrimethylammonium bromide, benzyltrimethylammonium hydroxide, benzyltributylammonium chloride, phenyltrimethylammonium chloride, etc. be done.

Specific examples of cyclic amines include 1,8-diazabicyclo(5,4,0)-7-undecene and 1,5-diazabicyclo(4,3,0)-5-nonene.

Specific examples of imidazoles include 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole and the like.
The catalysts (E) listed above may be used alone or in combination of two or more.

As the catalyst, it is preferable to use a tertiary amine having a boiling point higher than the reaction temperature, in order to allow the polymerization reaction to proceed smoothly.

When the catalyst (E) is used, the amount used is usually 10000 ppm by weight or less, for example 10 to 5000 ppm by weight, relative to the amount of the epoxy compound (A) used. When the amount of the catalyst used exceeds 10000 ppm by weight, the catalyst remaining in the modified epoxy resin induces anionic polymerization of epoxy groups, resulting in a marked decrease in storage stability.

[Reaction solvent (F)]
A reaction solvent (F) may be used in the reaction step for producing the modified epoxy resin. As the reaction solvent (F), any solvent can be used as long as it dissolves the raw materials, but it is usually an organic solvent.

Examples of organic solvents include aromatic solvents, ketone solvents, amide solvents, glycol ether solvents, and the like. Specific examples of aromatic solvents include benzene, toluene, and xylene. Specific examples of ketone solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, 2-heptanone, 4-heptanone, 2-octanone, cyclopentanone, cyclohexanone and acetylacetone. Specific examples of amide solvents include formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, 2-pyrrolidone, N-methylpyrrolidone and the like. Specific examples of glycol ether solvents include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol dimethyl ether, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol. mono-n-butyl ether, diethylene glycol dimethyl ether, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether, propylene glycol mono-n-butyl ether, propylene glycol monomethyl ether acetate and the like.

The reaction solvents (F) listed above may be used alone or in combination of two or more.
In addition, when a highly viscous product is generated during the reaction, the reaction solvent (F) can be further added to continue the reaction.

<Reaction conditions>
The reaction between the epoxy compound (A) and the acid-terminated polyester (B) can be carried out under normal pressure, increased pressure, or reduced pressure.
The reaction temperature is generally 60-240°C, preferably 80-220°C, more preferably 100-200°C. It is preferable that the reaction temperature is equal to or higher than the above lower limit because the reaction can easily proceed. Further, when the reaction temperature is equal to or lower than the above upper limit, the side reaction hardly progresses, which is preferable from the viewpoint of obtaining a highly pure modified epoxy resin.

Although the reaction time is not particularly limited, it is usually 0.5 to 24 hours, preferably 1 to 22 hours, more preferably 1.5 to 20 hours. When the reaction time is equal to or less than the above upper limit, it is preferable from the viewpoint of improving production efficiency, and when it is equal to or more than the above lower limit, it is preferable from the point of being able to reduce unreacted components.

[Dilution solvent (G)]
The modified epoxy resin may be mixed with a diluent solvent (G) after completion of the reaction to adjust the solid content concentration. As the diluting solvent (G), any solvent can be used as long as it dissolves the epoxy resin, but it is usually an organic solvent. As specific examples of the organic solvent, the same ones as those mentioned above as the reaction solvent (F) can be used.

In the present invention, the terms "solvent" and "solvent" are used to refer to those used during the reaction as "solvent" and those used after completion of the reaction as "solvent". Different species may be used.

[Curable resin composition]
A curable resin composition, which is one embodiment of the present invention, contains at least the above-described modified epoxy resin and a curing agent. In addition, if necessary, other epoxy compounds, curing accelerators, other components, and the like can be appropriately blended into the curable resin composition.

[Curing agent]
A curing agent is a substance that contributes to cross-linking and/or chain extension reactions between epoxy groups of an epoxy resin. In the present invention, even if a substance is usually called a "curing accelerator", it is regarded as a curing agent if it is a substance that contributes to the cross-linking reaction and/or chain extension reaction between the epoxy groups of the epoxy resin. do.
The content of the curing agent in the curable resin composition is preferably 0.1 to 1000 parts by weight, more preferably 100 parts by weight or less, and still more preferably 80 parts by weight with respect to 100 parts by weight of the modified epoxy resin. or less, particularly preferably 60 parts by weight or less.

In addition, when other epoxy compounds described later other than the modified epoxy resin are included, the content of the curing agent is preferably 0.1 to 1000 parts by weight with respect to 100 parts by weight of the total epoxy component as a solid content, It is more preferably 100 parts by weight or less, still more preferably 80 parts by weight or less, and particularly preferably 60 parts by weight or less.
A more preferred amount of curing agent is as described below, depending on the type of curing agent.

As used herein, the term "solid content" means components excluding solvent, and includes not only solid epoxy resins or epoxy compounds, but also semi-solid and viscous liquid substances. Further, "total epoxy component" means the sum of the modified epoxy resin and other epoxy compounds described later.

Curing agents include polyfunctional phenols, polyisocyanate compounds, amine compounds, acid anhydride compounds and acid-terminated polyester resins, imidazole compounds, amide compounds, cationic polymerization initiators, and organic phosphines. It is preferable to use at least one of

Examples of polyfunctional phenols include bisphenols such as bisphenol A, bisphenol F, bisphenol S, bisphenol B, bisphenol AD, bisphenol Z, tetrabromobisphenol A, 4,4'-biphenol, 3,3',5, Biphenols such as 5'-tetramethyl-4,4'-biphenol; catechol, resorcinol, hydroquinone, dihydroxynaphthalenes; and hydrogen atoms bonded to aromatic rings of these compounds are halogen groups, alkyl groups, aryl groups, ethers and those substituted with non-interfering substituents such as organic substituents containing heteroatoms such as group, ester group, sulfur, phosphorus, silicon and the like.
Furthermore, these phenols, phenol, cresol, polycondensation products of monofunctional phenols such as alkylphenols and aldehydes, novolacs and resols, etc., can also be used.

Examples of polyisocyanate compounds include tolylene diisocyanate, methylcyclohexane diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, dimer acid diisocyanate, trimethylhexamethylene diisocyanate, Examples include polyisocyanate compounds such as lysine triisocyanate. Further, a polyisocyanate compound obtained by reacting these polyisocyanate compounds with a compound having at least two active hydrogen atoms such as an amino group, a hydroxyl group, a carboxyl group and water, or 3 to 5 amounts of the above polyisocyanate compound. The body and the like can be mentioned.

Examples of amine compounds include aliphatic primary, secondary and tertiary amines, aromatic primary, secondary and tertiary amines, cyclic amines, guanidines, urea derivatives and the like. Ethylenetetramine, diaminodiphenylmethane, diaminodiphenyl ether, metaxylenediamine, dicyandiamide, 1,8-diazabicyclo(5,4,0)-7-undecene, 1,5-diazabicyclo(4,3,0)-5-nonene, dimethyl Urea, guanyl urea and the like can be mentioned.
Examples of acid anhydride compounds include phthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, and condensates of maleic anhydride and unsaturated compounds.
Examples of acid-terminated polyester resins include polycondensates obtained by reacting dihydric carboxylic acids and dihydric alcohols listed in the section of acid-terminated polyester (B).

Examples of imidazole compounds include 1-isobutyl-2-methylimidazole, 2-methylimidazole, 1-benzyl-2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, benzimidazole and the like. be done. Although the imidazole compound also functions as a curing accelerator, which will be described later, it is classified as a curing agent in the present invention.
Examples of amide compounds include dicyandiamide and derivatives thereof, and polyamide resins.

Cationic polymerization initiators generate cations upon exposure to heat or active energy rays, and include aromatic onium salts and the like. Specifically, anionic components such as SbF ₆ -, BF ₄ -, AsF ₆ -, PF ₆ -, CF ₃ SO ₃₂ -, B(C ₆ F ₅ ) ₄ - and iodine, sulfur, nitrogen, phosphorus, etc. A compound consisting of an aromatic cation component containing atoms and the like can be mentioned. Diaryliodonium salts and triarylsulfonium salts are particularly preferred.
Examples of organic phosphines include tributylphosphine, methyldiphenylphosphine, triphenylphosphine, diphenylphosphine, and phenylphosphine. Phosphonium salts include tetraphenylphosphonium/tetraphenylborate, tetraphenylphosphonium/ethyltriphenylborate, tetra Examples include butylphosphonium/tetrabutylborate and the like, and tetraphenylboron salts include 2-ethyl-4-methylimidazole/tetraphenylborate and N-methylmorpholine/tetraphenylborate.

When using a polyfunctional phenol, an amine compound, an acid anhydride compound, or an acid-terminated polyester resin as a curing agent, the functional groups in the curing agent for all epoxy groups in the curable resin composition (hydroxyl groups of the polyfunctional phenol , the amino group of the amine-based compound or the acid anhydride group of the acid anhydride-based compound) is preferably used so that the equivalent ratio is in the range of 0.8 to 1.5. When a polyisocyanate-based compound is used, the number of isocyanate groups in the polyisocyanate-based compound to the number of hydroxyl groups in the curable resin composition is in the range of 1:0.01 to 1:1.5 in terms of equivalent ratio. preferable. When an imidazole compound is used, it is preferably used in the range of 0.5 to 10 parts by weight with respect to 100 parts by weight of all epoxy components as solid content in the curable resin composition. When an amide compound is used, it is preferably used in the range of 0.1 to 20% by weight with respect to the total amount of all epoxy components and the amide compound as solid content in the curable resin composition. When a cationic polymerization initiator is used, it is preferably used in the range of 0.01 to 15 parts by weight with respect to 100 parts by weight of all epoxy components as solid content in the curable resin composition. When organic phosphines are used, they are preferably used in a range of 0.1 to 20% by weight based on the total amount of all epoxy components and organic phosphines as solid content in the curable resin composition.

In addition to the curing agents listed above, for example, mercaptan compounds, organic acid dihydrazides, halogenated boron amine complexes, and the like can also be used as curing agents.
These curing agents may be used alone or in combination of two or more.

[Other epoxy compounds]
Epoxy compounds other than the above modified epoxy resin (in this specification, may be referred to as "another epoxy compound") can be used in the curable resin composition.
Other epoxy compounds include, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, biphenyl type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, bisphenol A novolak type epoxy resin. , Tetrabromobisphenol A type epoxy resin, glycidyl ether type epoxy resin such as other polyfunctional phenol type epoxy resin, epoxy resin obtained by hydrogenating the aromatic ring of the above aromatic epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy Epoxy compounds such as resins, linear aliphatic epoxy resins, alicyclic epoxy resins, and heterocyclic epoxy resins can be mentioned. The other epoxy compounds listed above may be used alone or in combination of two or more.

When the curable resin composition contains the modified epoxy resin and another epoxy compound, the proportion of the other epoxy compound in the total epoxy component as a solid content in the epoxy resin-containing composition is preferably 1 weight. % or more, more preferably 5 wt % or more, and preferably 99 wt % or less, more preferably 95 wt % or less. When the proportion of the other epoxy compound is at least the above lower limit, it is possible to sufficiently obtain the effect of improving physical properties by blending the other epoxy compound. On the other hand, when the ratio of the other epoxy compound is equal to or less than the above upper limit, the effect of improving the flexibility of the modified epoxy resin can be obtained.

[solvent]
The curable resin composition may be mixed with and diluted with a solvent in order to appropriately adjust the viscosity of the epoxy resin-containing composition during handling such as coating film formation. In the curable resin composition, the solvent is used to ensure handleability and workability in molding the curable resin composition, and there is no particular limitation on the amount used. As described above, in the present invention, the terms "solvent" and "solvent" are used separately depending on the mode of use, but the same type or different types may be used independently.
As the solvent that the modified epoxy resin may contain, one or more of the organic solvents exemplified as the reaction solvent (F) used in the production of the modified epoxy resin can be used.

[Other ingredients]
The curable resin composition may contain other components in addition to the components listed above. Other components include, for example, curing accelerators (excluding those corresponding to the above curing agents), coupling agents, flame retardants, antioxidants, light stabilizers, plasticizers, reactive diluents, pigments, Examples include inorganic fillers and organic fillers. The other components listed above can be used in appropriate combination depending on the desired physical properties of the epoxy resin-containing composition.
The fact that the above compound is blended in the curable resin composition can be confirmed by SEC-MALS, elemental analysis, and functional group analysis after separation and purification of the epoxy resin composition.

[Cured product]
A cured product can be obtained by curing the curable resin composition. The term "curing" as used herein means intentionally curing the epoxy resin with heat and/or light, and the degree of curing may be controlled according to desired physical properties and applications.
The curing method for curing the curable resin composition to obtain a cured product varies depending on the ingredients and amounts in the curable resin composition and the shape of the compound, but is usually 50 to 200 ° C. for 5 seconds. Heating conditions of ~180 minutes can be mentioned. This heating should be carried out in two stages: primary heating at 50 to 160°C for 5 seconds to 30 minutes, and secondary heating at 90 to 200°C, which is 40 to 120°C higher than the primary heating temperature, for 1 minute to 150 minutes. is preferable from the viewpoint of reducing poor curing.

When a cured product is produced as a semi-cured product, the curing reaction of the curable resin composition may be allowed to proceed by heating or the like to such an extent that the shape can be maintained. When the curable resin composition contains a solvent, most of the solvent is removed by heating, depressurization, air drying, etc., but 5% by weight or less of the solvent may remain in the semi-cured product. .
The presence of the modified epoxy resin in the cured product can be confirmed by identifying the modified epoxy resin from the cured product by infrared spectroscopy of the cured product.

[Use]
The present invention relates to a modified epoxy resin excellent in flexibility and adhesiveness, a curable resin composition containing this modified epoxy resin, and a cured product. The above-mentioned modified epoxy, curable resin composition, and cured product are excellent in electrical properties, adhesiveness, flexibility, heat resistance, etc., and are mainly used in many applications in the fields of coatings, adhesives, civil engineering, and electrical fields. It can be used particularly preferably in the field of paints and adhesive applications.

Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited by the following examples. It should be noted that various production conditions and values of evaluation results in the following examples have the meaning of preferred values for the upper limit or lower limit in the embodiments of the present invention, and the preferred range is the above-described upper limit or lower limit value. , the range defined by the values in the following examples or a combination of the values in the examples.

The epoxy resins, acid-terminated polyesters, and evaluation methods used in the following examples and comparative examples are as follows.
[Epoxy compound (A)]
The following A-1 to A-7 were used as the epoxy compound (A).
A-1: 1,6-hexanediol diglycidyl ether (manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 116 g/eq, liquid)
A-2: Bisphenol A type epoxy resin (manufactured by Mitsubishi Chemical Corporation jER (registered trademark) 828US, epoxy equivalent: 186 g / eq, liquid)
A-3: Bisphenol F type epoxy resin (manufactured by Mitsubishi Chemical Corporation jER (registered trademark) 806H, epoxy equivalent: 169 g / eq, liquid)
A-4: Polyoxypropylene glycol diglycidyl ether (manufactured by Sanyo Chemical Co., Ltd. Glycier PP300P, epoxy equivalent: 296 g / eq, liquid)
A-5: Resorcinol-type epoxy resin (Denacol EX-201 manufactured by Nagase ChemteX Corporation, epoxy equivalent: 113 g/eq, liquid)
A-6: Ultra-flexible epoxy resin (YX7110 manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 1000 g / eq, semi-solid)
A-7: Dimer acid type epoxy resin (manufactured by Mitsubishi Chemical Corporation jER (registered trademark) 871, epoxy equivalent: 415 g / eq, liquid)

[Acid-terminated polyester (B)]
B-1 to B-5 shown in Table 1 were used as the acid-terminated polyester (B). All of them are obtained by reacting dihydric carboxylic acids and dihydric alcohols shown in Table-1.
Hereinafter, production methods, acid values, carboxylic acid equivalents, hydroxyl values, glass transition temperatures, acid terminal purities, weight average molecular weights and number average molecular weights of B-1 to B-5 are shown in order.

<Production of B-1 to B-5>
Synthesis of B-1 to B-5 was carried out as follows. First, 1000 ppm of tetrabutoxytitanium with respect to the total weight of the dihydric carboxylic acid component and the dihydric alcohol component shown in Table 1 was put into a reaction vessel equipped with a distillation column. Next, while stirring, the temperature was started to rise, and the temperature in the reaction system was heated to 265°C, and this temperature was maintained. After the esterification reaction is completed and no more water is distilled out from the reaction system, the pressure in the reaction system is reduced while maintaining the temperature in the reaction system at 265° C. to distill off the dihydric alcohol component from the reaction system. Condensation reaction was carried out while letting out.
The viscosity of the reaction system increases with the reaction, and when the torque of the stirring blade reaches a predetermined torque, the stirring is stopped, the reaction system is returned to normal pressure, and pressurized with nitrogen to take out the reactant, and B-1 to B-5 was produced.

<Measurement of acid value/carboxylic acid equivalent>
The acid value of the acid-terminated polyester (B) was measured by the following procedure.
About 0.2 g of acid-terminated polyester (B) was precisely weighed in a side-armed Erlenmeyer flask (A (g)), 10 mL of benzyl alcohol was added, and the mixture was heated under a nitrogen atmosphere with a heater at 230°C for 15 minutes to dissolve completely. did. After allowing to cool to room temperature, 10 mL of benzyl alcohol, 20 mL of chloroform, and several drops of phenolphthalein solution were added and titrated with a 0.02N KOH solution (titration = B (mL), titer of KOH solution = p). . A blank measurement was performed in the same manner (titration = C (mL)), and the acid value was calculated according to the following formula.
Acid value (mgKOH/g) = {(BC) x 0.02 x 56.11 x p}/A
Subsequently, the acid equivalent was calculated according to the following formula from the obtained acid value (mgKOH/g).
Carboxylic acid equivalent (g/eq) = 56.11/acid value (mgKOH/g) x 1000

<Measurement of hydroxyl value>
The hydroxyl value of the acid-terminated polyester (B) was measured by the following procedure.
Solution 1: About 5 g of acid-terminated polyester (B) was precisely weighed into a side-armed Erlenmeyer flask (A (g)), and 50 mL of THF was added to dissolve completely.
Solution 2: 30 mL of dimethylaminopyridine THF solution prepared by dissolving 5 g of N,N-dimethylaminopyridine in 500 mL of THF was added to "Solution 1".
Prepare an acetic anhydride THF solution by adding 200 mL of THF to 22 mL of acetic anhydride, add 10 mL of this solution to "solution 2", and mix for 20 minutes to obtain "solution 3". Add 3 mL of ion-exchanged water to "Solution 3" and mix for 20 minutes to obtain "Solution 4". "Solution 5" is obtained by adding 50 mL of THF to "Solution 4". "Solution 6" is obtained by adding 25 mL of 0.5N-KOH methanol solution and phenolphthalein indicator to "Solution 5". "Solution 6" is titrated with a 0.5N-KOH methanol solution, and the added amount is measured at the point where the solution turns slightly purple (B (mL)). The titration amount (C (mL)) required for blank measurement was also confirmed at the same time, and the hydroxyl value was calculated according to the following formula using the acid value obtained above and the titer p of the 0.5N-KOH methanol solution.
Hydroxyl value (mgKOH/g) = [acid value] + {(CB) x 0.5 x 56.11 x p}/A

<Measurement of Tg (glass transition temperature)>
The glass transition temperature of the acid-terminated polyester (B) was measured using a differential scanning calorimeter DSC-60 manufactured by Shimadzu Corporation at a heating rate of 5 ° C./min. It was obtained as the temperature at the intersection with the tangent line of the endothermic curve near the transition temperature.

<Calculation of acid terminal purity>
Acid terminal purity was calculated according to the following formula.
Acid terminal purity = number average molecular weight/carboxylic acid equivalent (g/eq)
In this example, since a dihydric carboxylic acid and a dihydric alcohol are polycondensed to produce a linear acid-terminated polyester, one molecule ideally has two carboxylic acids. That is, the closer the calculated acid terminal purity is to 2, the higher the acid terminal purity. If the acid terminal purity is high, the epoxy group terminal purity of the modified epoxy resin is also high, and a three-dimensional network structure as designed can be formed during curing.

<Measurement of Weight Average Molecular Weight and Number Average Molecular Weight>
The weight average molecular weight and number average molecular weight of the acid-terminated polyester (B) were measured by gel permeation chromatography (GPC). The apparatus and measurement conditions used for GPC measurement are as follows.
Apparatus: GPC
Model: HLC-8020GPC (manufactured by Tosoh)
Column: Three TSKgelGMHXL (column size: 7.8 mm (ID) × 30.0 cm (L)) connected in series (manufactured by Tosoh)
Detector: RI (manufactured by Tosoh)
Eluent: THF (1 mL/min, 40°C)
Sample: 0.04% tetrahydrofuran solution (100μ injection)
Calibration curve: standard polystyrene (manufactured by Tosoh)

〔Evaluation method〕
Evaluation methods in the following examples and comparative examples are as follows.
[Epoxy equivalent]
Epoxy equivalents in Examples and Comparative Examples were measured according to JIS K 7236.

[Number average molecular weight (Mn), weight average molecular weight (Mw)]
The weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw/Mn) in Examples and Comparative Examples were measured by gel permeation chromatography (GPC). The apparatus and measurement conditions used for GPC measurement are as follows.
Apparatus: GPC
Model: HLC-8120GPC (manufactured by Tosoh)
Column: TSKGEL HM-H + H4000 + H4000 + H3000 + H2000 (manufactured by Tosoh)
Detector: UV-8020 (manufactured by Tosoh), 254 nm
Eluent: THF (0.5 mL/min, 40°C)
Sample: 1% tetrahydrofuran solution (10 μL injection)
Calibration curve: standard polystyrene (manufactured by Tosoh)

[Glass transition temperature (Tg)]
The glass transition point (Tg) in the examples and comparative examples was measured using a differential scanning calorimeter "DSC7020" manufactured by SII Nanotechnology Co., Ltd. by heating from -50 to 200°C at a rate of 10°C/min. rice field. It was obtained as the temperature at the intersection of the base line on the low temperature side of the chart measured at a heating rate of 10°C/min and the tangent line of the endothermic curve in the vicinity of the glass transition temperature.

[Melting point]
Melting points in Examples and Comparative Examples were measured using a melting point measuring instrument "ATM-02" manufactured by AS ONE Corporation.
[viscosity]
Viscosities in Examples and Comparative Examples were measured at 25° C. and 70° C. using a cone-plate viscometer.

[Properties]
In the examples and comparative examples, the state of the resin at 23° C. was classified into four types: liquid, solid, high-viscosity liquid and crystalline solid.
[Evaluation method of cured product]
For evaluation of cured products in Examples and Comparative Examples, handling properties were evaluated by compounding according to the compounding ratio in Table 3 and curing. Dicyandiamide (DICY) was used as a curing agent, and 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) was used as a curing accelerator. A tensile test and a T-peel test were performed using the cured product to comprehensively determine the flexibility and adhesiveness.

<Handleability>
Two items of miscibility and reactivity with the curing agent were evaluated for handleability.
The miscibility was evaluated as follows to determine whether or not each component was easily mixed uniformly at the time of blending, and was used as an index. If the miscibility rating was C or lower, no further evaluation was performed.
≪Evaluation Criteria≫
A: Easy to mix.
B1: The formulation is highly viscous and requires heating, but can be easily mixed.
B2: The formulation is crystalline and requires warming, but is easily miscible.
C: It is difficult to mix uniformly because the viscosity of the formulation is remarkably high.

The reactivity with the curing agent was obtained by preheating the composition at 80° C. for 1 hour and then heating it at 130° C. for 1.5 hours to cure the cured product. When the evaluation of reactivity with the curing agent was x, subsequent evaluation was not performed.
≪Evaluation Criteria≫
◯: A uniformly cured product is obtained.
x: The cured product is separated and not cured.

<Glass transition temperature (Tg)>
A portion of the tensile test piece was used and measured in the same manner as in the section [Glass transition temperature (Tg) and melting point]. The extrapolated glass transition start temperature (Tig) is the intersection of a straight line extending the base line on the low temperature side to the high temperature side and a tangent line drawn at a point where the gradient of the stepwise change portion of the glass transition curve is maximized. was the temperature of The midpoint glass transition temperature (Tmg) was taken as the temperature at the point where a straight line equidistant from the extended straight line of each base line intersects the curve of the stepwise change portion of the glass transition.

<Tensile test>
After preheating the formulation at 80° C. for 1 hour, it was cured by heating at 130° C. for 1.5 hours to prepare a cured plate having a thickness of 3 mm. This cured product was processed into a dumbbell shape to obtain a test piece. The tensile strain at break of the obtained test piece was measured according to JIS K7161 using a precision universal testing machine "INSTRON 5582 type" manufactured by Instron. The value of the tensile breaking strain was evaluated as follows and used as an index.
≪Evaluation Criteria≫
S: 80% or more.
A: 40% or more and less than 80%.
B: 7% or more and less than 40%.
C: 5% or more and less than 7%.
D: Less than 5%.

<T-type peel test>
0.02 parts of glass beads J-100 (particle diameter: 100 µm) were added to 10 parts of the compound and mixed to prepare a coating solution.
A degreased steel plate (JISG3141 SPCC-SD, manufactured by Engineering Test Service Co., Ltd.) having a width of 25 mm, a length of 200 mm, and a thickness of 0.5 mm was used as the substrate. The coating liquid is applied to two substrates, the coated surfaces are bonded together and fixed, preheated at 80 ° C. for 1 hour, and then cured by heating at 130 ° C. for 1.5 hours to obtain a laminate. rice field. The hardened material protruding from the side surface of the laminate was scraped off, and the gripping margins of the two steel plates were bent outward at a right angle by 90° to obtain a T-shaped test piece.

Using a precision universal testing machine "INSTRON 5582 type" manufactured by Instron, the peel adhesive strength of the obtained test piece was measured according to JIS K6854. The value of the peel adhesive strength was evaluated as follows and used as an index.
≪Evaluation Criteria≫
S: 100 N/25 mm or more.
A: 15 N/25 mm or more and less than 100 N/25 mm.
B: 10 N/25 mm or more and less than 15 N/25 mm.
C: less than 10 N/25 mm.

<Comprehensive evaluation>
The results of handleability, tensile test, and T-type peel test were comprehensively judged, evaluated as follows, and used as an index.
S: Fully satisfies the practical level.
A: It satisfies the practical level.
B: Does not satisfy the practical level.
C: Does not satisfy the practical level at all.
D: Not worthy of evaluation.

(Comparative Examples 1-3, Examples 1-7)
Epoxy compound (A), acid-terminated polyester (B), and N,N-dimethylbenzylamine (1000 ppm with respect to the charged weight of epoxy compound (A)) were placed in a reactor according to the charged weights shown in Table-2. , under a nitrogen gas atmosphere at 150°C for 6 hours, to obtain a modified epoxy resin.
The resulting modified epoxy resin was measured for epoxy equivalent, weight average molecular weight (Mw), number average molecular weight (Mn), molecular weight distribution (Mw/Mn), Tg, melting point, properties, and viscosity. rice field.

(Comparative Examples a to f, Examples a to g)
After compounding and curing according to the compounding ratio in Table-3 and confirming the handleability, Tg measurement, tensile test, and T-type peel test were performed, and the results are summarized in Table-3.

[Evaluation results]
As can be seen from the examples and comparative examples in Table 3, a modified epoxy resin containing a structural unit (X) derived from an epoxy resin and a structural unit (Y) derived from an acid-terminated polyester represented by formula (1) It has a weight average molecular weight of 3000 to 50000 and an epoxy equivalent of 500 to 10000 g / eq. It has excellent reactivity with curing agents, and can exhibit its properties even when blended with other epoxy resins.

Claims

A modified epoxy resin comprising an epoxy resin-derived structural unit (X) and an acid-terminated polyester-derived structural unit (Y) represented by the following formula (1),
A weight average molecular weight of 3000 to 50000 and an epoxy equivalent of 500 to 10000 g / eq,
A modified epoxy resin in which the ratio of the structural unit (Y) derived from an acid-terminated polyester in the formula (1) is 50 to 90% by weight.

(In the above formula (1), n is the average number of repetitions and is a positive number of 1 to 10. X is a divalent group represented by the following formula (2), and Y is the following formula (3 ) is a divalent group represented by

(In formula (2) above, R 1 is a hydrocarbon group having 2 to 40 carbon atoms and may have a heteroatom. p is a repeating number and is an integer of 0 to 10.)

(In the above formula (3), R 2 is a hydrocarbon group having 2 to 40 carbon atoms, may have a heteroatom, and the proportion of the aliphatic hydrocarbon group in all of R 2 is 50 mol% or more. R 3 is a hydrocarbon group having 2 to 30 carbon atoms and may have a heteroatom, q is a repeating number and is an integer of 1 to 50.)
2. The modified epoxy resin according to claim 1, wherein the proportion of aliphatic hydrocarbon groups having 3 or less carbon atoms in the entirety of R3 in formula ( 3 ) is 50 mol % or more.
The modified epoxy resin according to claim 1 or 2, wherein said R 1 contains a divalent group represented by the following formula (4) and/or the following formula (5).

(In formula (4) above, R 4 is a single bond, or -CH 2 -, -C(CH 3 ) 2 -, -CH(CH 3 )-, -S-, -SO 2 -, -O- , and —CO— R 5 is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a phenyl group; may be different.)

(In formula (5) above, R 6 is selected from the group consisting of a hydrogen atom and a hydrocarbon group having 1 to 20 carbon atoms, each of which may be the same or different, and part of R 6 is , may form a ring condensed to this benzene ring.)
The modified epoxy resin according to any one of claims 1 to 3, wherein said R 1 is a divalent group represented by the following formula (6).

(R 7 in the above formula (6) is a hydrocarbon group having 1 to 10 carbon atoms. r is the number of repetitions and is an integer of 0 to 20.)
The modified epoxy resin according to any one of claims 1 to 4, wherein the modified epoxy resin has a molecular weight distribution (Mw/Mn) of 1.5 to 20.
Modified according to any one of claims 1 to 5, obtained by reacting an epoxy compound (A) represented by the following formula (7) with an acid-terminated polyester (B) represented by the following formula (8). A method for producing an epoxy resin.

(In formula (7) above, R 1 and p have the same meanings as in formula (2) above.)

(In formula (8) above, R 2 , R 3 and q have the same meanings as in formula (3) above.)
A curable resin composition comprising the modified epoxy resin according to any one of claims 1 to 5 and a curing agent.
A cured product obtained by curing the curable resin composition according to claim 7.
A paint containing the cured product according to claim 8.
An adhesive comprising the cured product according to claim 8 .