JP2021011545A - Polyurethane and curable composition - Google Patents

Abstract

To provide a polyurethane that can give a curable composition the performance of preventing warpage of an over coat film or a flexible wiring board.SOLUTION: A polyurethane has a first urethane constitutional unit, a second urethane constitutional unit, and a third urethane constitutional unit. Each of the first urethane constitutional unit, second urethane constitutional unit, and third urethane constitutional unit have a 1,3-phenylenedimethylene group, a 1,3-cyclohexanedimethylene group, or a trans 1,4-cyclohexanedimethylene group represented by the formula (6).SELECTED DRAWING: None

Description

The present invention relates to polyurethane, a curable composition, a cured product, an overcoat film, a flexible wiring board, and a method for producing the same.

The flexible wiring board is coated with an overcoat film to protect the surface. This overcoat film is formed by applying a curable composition to the surface of a flexible substrate on which wiring is formed by a printing method or the like and curing it. As the circuit formed on the flexible wiring board is processed into fine wiring and the module is made lighter and smaller, the curable composition for forming the overcoat film causes the overcoat film to warp as compared with the conventional one. Difficult performance is required. If the overcoat film is warped, the flexible wiring board will be warped, and as a result, in the mounting process for mounting the IC chip on the flexible wiring board, the alignment accuracy of the mounting position of the IC chip will be adversely affected. Yield may be low.

A large number of curable compositions for forming an overcoat film of a flexible wiring board have been conventionally proposed. For example, Patent Document 1 contains polyurethane obtained by reacting a diisocyanate compound with a plurality of types of diol compounds. Curable compositions are disclosed. By using the curable composition disclosed in Patent Document 1, it is possible to obtain an overcoat film for a flexible wiring board which is excellent in low warpage, flexibility, long-term insulation reliability, and wire breakage suppression property.

International Publication No. 2017/110591

However, with the development of the semi-additive method, the distance (pitch) between wirings of the flexible wiring board is expected to be further narrowed (for example, 20 μm or less). Therefore, regarding the low warpage of the overcoat film and the flexible wiring board, Further improvement was desired.
An object of the present invention is to provide a curable composition having excellent performance of preventing warpage of an overcoat film or a flexible wiring board. Another object of the present invention is to provide a polyurethane capable of imparting a curable composition to a performance that does not easily cause warpage in an overcoat film or a flexible wiring board. Another object of the present invention is to provide a cured product having low warpage and an overcoat film. Another object of the present invention is to provide a flexible wiring board having low warpage and a method for manufacturing the same.

One aspect of the present invention is as follows [1] to [16].
[1] A first urethane structural unit represented by the following formula (1), a second urethane structural unit represented by the following formula (2), and a third urethane structure represented by the following formula (3). Have a unit,
X number of R ¹ in formula (1) are each independently, 1,3-phenylene methylene group represented by the following formula (4) is represented by the following formula (5) 1,3 It represents a cyclohexanedimethylene group or a trans-type 1,4-cyclohexanedimethylene group represented by the following formula (6), and x is an integer of 1 or more.
Y-number of R ¹ in formula (2) are each independently, 1,3-phenylene methylene group represented by the following formula (4) is represented by the following formula (5) 1,3 cyclohexane dimethylene group, or a trans type 1,4cyclohexanedimethylene group represented by the following formula (6), (n × y ) number of R ² is 6 to 14 carbon atoms each independently represents a divalent organic group, [(n + 1) × y] number of R ³ each independently represents a divalent hydrocarbon group having 3 to 9 carbon atoms, the y-number of n, each independently It is an integer of 0 or more and 50 or less, however, y n is not all 0, and y is an integer of 1 or more.
Z number of R ¹ of formula (3) in each independently, 1,3-phenylene methylene group represented by the following formula (4) is represented by the following formula (5) 1,3 cyclohexane dimethylene group, or a trans type 1,4cyclohexanedimethylene group represented by the following formula (6), z number of R ⁴ each independently represents a methyl group or an ethyl group, z is Polyurethane that is an integer greater than or equal to 1.

[2] The polyurethane according to [1], wherein the ratios of x in the formula (1), y in the formula (2), and z in the formula (3) to x + y + z satisfy the following conditions, respectively.
0.01 ≤ x / (x + y + z) ≤ 0.4
0.1 ≤ y / (x + y + z) ≤ 0.9
0.01 ≤ z / (x + y + z) ≤ 0.4

[3] The polyurethane according to [1] or [2], which has a number average molecular weight of 10,000 or more and 50,000 or less.
[4] The polyurethane according to any one of [1] to [3], which has an acid value of 10 mgKOH / g or more and 70 mgKOH / g or less.
[5] The polyurethane according to any one of [1] to [4], wherein the aromatic ring concentration is 0.1 mmol / g or more and 5.0 mmol / g or less.

[6] The polyurethane (a) according to any one of [1] to [5], the solvent (b), and the epoxy compound (c) having two or more epoxy groups in one molecule are used. Curable composition to contain.
[7] The ratio of the content of the solvent (b) to the total amount of the polyurethane (a), the solvent (b) and the epoxy compound (c) is 25% by mass or more and 75% by mass or less, and the polyurethane ( The ratio of the content of the polyurethane (a) to the total amount of the polyurethane (a) and the epoxy compound (c) is 40% by mass or more and 99% by mass or less, and the total amount of the polyurethane (a) and the epoxy compound (c). The curable composition according to [6], wherein the ratio of the content of the epoxy compound (c) to the epoxy compound (c) is 1% by mass or more and 60% by mass or less.

[8] The curable composition according to [6] or [7], which further contains at least one fine particle (d) selected from the group consisting of inorganic fine particles and organic fine particles.
[9] The curable composition according to [8], wherein the fine particles (d) contain silica fine particles.
[10] The curable composition according to [8], wherein the fine particles (d) contain hydrotalcite fine particles.

[11] The ratio of the content of the solvent (b) to the total amount of the polyurethane (a), the solvent (b), the epoxy compound (c) and the fine particles (d) is 25% by mass or more and 75% by mass or less. The ratio of the content of the fine particles (d) is 0.1% by mass or more and 60% by mass or less.
The ratio of the content of the polyurethane (a) to the total amount of the polyurethane (a) and the epoxy compound (c) is 40% by mass or more and 99% by mass or less, and the ratio of the content of the epoxy compound (c) is 1% by mass. The curable composition according to any one of [8] to [10], which is% or more and 60% by mass or less.

[12] A cured product of the curable composition according to any one of [6] to [11].
[13] An overcoat film containing the cured product according to [12].
[14] A flexible wiring board in which a portion of the surface of a flexible substrate on which wiring is formed is covered with the overcoat film according to [13].
[15] The flexible wiring board according to [14], wherein the wiring is tin-plated copper wiring.
[16] After the curable composition according to any one of [6] to [11] is arranged in a film shape on the portion of the surface of the flexible substrate on which the wiring is formed, where the wiring is formed. A method for producing a flexible wiring board, wherein the film-like curable composition is cured to form an overcoat film.

The curable composition according to the present invention is excellent in the ability to prevent warping of the overcoat film and the flexible wiring board. The polyurethane according to the present invention can impart to the curable composition the ability to prevent warpage of the overcoat film and the flexible wiring board. The cured product, overcoat film, and flexible wiring board according to the present invention have excellent low warpage. The method for manufacturing a flexible wiring board according to the present invention can manufacture a flexible wiring board having low warpage.

An embodiment of the present invention will be described below. It should be noted that the present embodiment shows an example of the present invention, and the present invention is not limited to the present embodiment. In addition, various changes or improvements can be added to the present embodiment, and the modified or improved forms may be included in the present invention.

As a result of diligent research to solve the above problems, the present inventors have obtained an overcoat film obtained by curing the curable composition by using a curable composition containing polyurethane having a specific structure. Further, they have found that the flexible wiring plate is less likely to warp, and have completed the present invention.

I. Polyurethane The polyurethane of the present embodiment is represented by the first urethane structural unit represented by the above formula (1), the second urethane structural unit represented by the above formula (2), and the above formula (3). It has a third urethane structural unit. In addition, other structural units may be further provided as long as the effects of the present invention are not impaired.

X number of R ¹ in the formula (1) are each independently, 1,3-phenylene methylene group represented by the formula (4), represented by the formula (5) 1,3 It represents a cyclohexanedimethylene group or a trans-type 1,4-cyclohexanedimethylene group represented by the above formula (6), and x is an integer of 1 or more. x is preferably 1 or more and 15 or less, more preferably 2 or more and 12 or less, and further preferably 3 or more and 10 or less.

Y-number of R ¹ in the formula (2) are each independently, 1,3-phenylene methylene group represented by the formula (4), represented by the formula (5) 1,3 A cyclohexanedimethylene group or a trans-type 1,4-cyclohexanedimethylene group represented by the above formula (6) is shown. Further, (n × y) R ² independently represent a divalent organic group having 6 or more and 14 or less carbon atoms, and [(n + 1) × y] R ³ independently represent carbon. It represents a divalent hydrocarbon group of number 3 or more and 9 or less, and y n is an integer of 0 or more and 50 or less independently. However, y n are not all 0. Further, y is an integer of 1 or more. y is preferably 1 or more and 15 or less, more preferably 2 or more and 12 or less, and further preferably 3 or more and 10 or less.

Z number of R ¹ in the formula (3) are each independently 1,3-phenylene methylene group represented by the formula (4), represented by the formula (5) 1,3 A cyclohexanedimethylene group or a trans-type 1,4-cyclohexanedimethylene group represented by the above formula (6) is shown. Further, z number of R ⁴ represents a methyl group or an ethyl group independently. Further, z is an integer of 1 or more. z is preferably 1 or more and 15 or less, more preferably 2 or more and 12 or less, and further preferably 3 or more and 10 or less.

It is preferable that the ratios of x in the above formula (1), y in the above formula (2), and z in the above formula (3) to x + y + z satisfy the following conditions, respectively.
0.01 ≤ x / (x + y + z) ≤ 0.4
0.1 ≤ y / (x + y + z) ≤ 0.9
0.01 ≤ z / (x + y + z) ≤ 0.4

Further, it is more preferable that the ratios of x in the above formula (1), y in the above formula (2), and z in the above formula (3) to x + y + z satisfy the following conditions, respectively.
0.02 ≤ x / (x + y + z) ≤ 0.3
0.2 ≤ y / (x + y + z) ≤ 0.8
0.02 ≤ z / (x + y + z) ≤ 0.3

R ¹ in the above formulas (1), (2) and (3) is a 1,3-phenylenedimethylene group represented by the above formula (4), and 1, represented by the above formula (5). Since it is a 3-cyclohexanedimethylene group or a trans-type 1,4-cyclohexanedimethylene group represented by the above formula (6), the polyurethane of the present embodiment warps the overcoat film and the flexible wiring board. It is possible to impart a performance that is difficult to prevent to the curable composition. Therefore, if the curable composition containing polyurethane of the present embodiment is cured to produce an overcoat film or a flexible wiring board, an overcoat film or a flexible wiring board having low warpage (small warpage) can be obtained. it can.

It should be noted that R ¹ in the above equations (1), (2), and (3) may be all the same, some may be different, and all other parts may be the same, or all may be different. You may.
When R ¹ is a 1,3-cyclohexanedimethylene group, R ¹ may be a trans-type 1,3-cyclohexanedimethylene group or a cis-type 1,3-cyclohexanedimethylene group. , A mixture of trans and cis types may be a 1,3-cyclohexanedimethylene group.

(N × y) pieces of R ² in the formula (2) each independently is a divalent organic group having 6 to 14 carbon atoms, a phenylene group, phenylene group having a substituent group are preferred, A 1,2-phenylene group and a 1,2-phenylene group having a substituent are more preferable. Examples of the substituent include an alkyl group having 1 to 5 carbon atoms, a halogen atom and the like. Specific examples of R ² include 1,2-phenylene group, 1,3-phenylene group, 1,4-phenylene group, 3-methyl-1,2-phenylene group, 4-methyl-1,2-phenylene group. , 4-Methyl-1,3-phenylene group, 2-methyl-1,4-phenylene group, 3-chloro-1,2-phenylene group, 4-chloro-1,2-phenylene group, 4-chloro-1 , 3-Phenylene group, 2-Chloro-1,4-Phenylene group, 3-Bromo-1,2-Phenylene group, 4-Bromo-1,2-Phenylene group, 4-Bromo-1,3-Phenylene group, 2-bromo-1,4-phenylene group and the like can be mentioned. Incidentally, (n × y) number of R ² is, wholly may be the same, partially different to all other parts may be the same or may be entirely different.

Among these, at least one R ² out of (n × y) R ² is a 1,2-phenylene group, a 1,3-phenylene group, a 3-methyl-1,2-phenylene group, 4-. is preferably any one group selected from the group consisting of methyl-1,2-phenylene group and 4-methyl-1,3-phenylene group, at least one of the (n × y) pieces of R ² More preferably, R ² is a 1,2-phenylene group or a 1,3-phenylene group, and at least one R ² out of (n × y) R ² is a 1,2-phenylene group. Is even more preferable.

[(N + 1) × y] number of R ³ in the formula (2) in represents a divalent hydrocarbon group having 3 to 9 carbon atoms independently. As the divalent hydrocarbon group having 3 or more and 9 or less carbon atoms, an alkylene group and a cycloalkylene group are preferable, and an alkylene group is more preferable. Preferred alkylene groups include, for example, groups represented by the following formulas (7) to (17). [(N + 1) × y] R ³ may be all the same, some may be different, and all the other parts may be the same, or all may be different.

Then, the equation (2) of [(n + 1) × y] pieces of at least one R ³ out of R ^3, the following equation (10), equation (11) is represented by any one of formula (12) is preferably that group, with a group of at least one of R ³ of the above formula (2) in the [(n + 1) × y] number of R ³ is represented by the formula (11) or (12) more preferably in, it is more preferably a group all of the above formula (2) in [(n + 1) × y] number of R ³ is represented by the formula (11) or formula (12).
The y n in the above formula (2) are independently integers of 0 or more and 50 or less, but it is preferable that they are independently integers of 1 or more and 20 or less.

The method of synthesizing the polyurethane of the present embodiment but is not particularly limited, for example, in the presence or absence of a urethane-forming catalyst such as dibutyltin dilaurate, diisocyanate compound (OCN-R ¹ -NCO), following Examples thereof include a method of polymerizing three kinds of diol compounds represented by the formulas (18), (19) and (20) in a solvent.

If desired, a polyol other than the three diol compounds represented by the following formulas (18), (19), and (20), a monohydroxy compound having one hydroxy group in one molecule, and one molecule. At least one of the monoisocyanate compounds having one isocyanato group may coexist in the compound to carry out the above polymerization reaction.
Further, it is preferable to carry out the above polymerization reaction without a catalyst or in the presence of a small amount of catalyst because the long-term insulation reliability of the overcoat film described later is improved.

Diisocyanate compound OCN-R ¹ -NCO of R ^1, the above equation (1), (2) are the same as R ¹ in (3), description thereof is omitted. That is, this diisocyanate compound is 1,3-bis (isocyanatomethyl) benzene, 1,3-bis (isocyanatomethyl) cyclohexane, or trans-1,4-bis (isocyanatomethyl) cyclohexane.

The diol compound represented by the above formula (18) is 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene.
Furthermore, R ^2, R ³ in the formula (19), n is the same as R ^2, R ^3, n in the above formula (2), description thereof is omitted. Further, R ⁴ in the formula (20) are the same as R ⁴ in the formula (3), description thereof is omitted.

As the diol compound represented by the above formula (19), at least one selected from the group of the following dicarboxylic acids and at least one selected from the group of the following diols are combined and subjected to an esterification reaction. Examples of polyester polyols to be produced.
Examples of the dicarboxylic acid include orthophthalic acid, isophthalic acid, terephthalic acid, 3-methyl-benzene-1,2-dicarboxylic acid, 4-methyl-benzene-1,2-dicarboxylic acid, 4-methyl-benzene-1, Examples thereof include 3-dicarboxylic acid, 5-methyl-benzene-1,3-dicarboxylic acid, 2-methyl-benzene-1,4-dicarboxylic acid and the like.

Among the above dicarboxylic acids, orthophthalic acid and 3-methyl, from the viewpoint of simultaneously suppressing the crystallinity and the hydrolyzability of the ester bond in order to develop low warpage and good long-term insulation reliability. −benzene-1,2-dicarboxylic acid and 4-methyl-benzene-1,2-dicarboxylic acid are more preferable, and orthophthalic acid is even more preferable.

Examples of the diol include 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 3-methyl-1,5. -Pentanediol, 1,8-octanediol, 1,9-nonanediol, 2,4-diethyl-1,5-pentanediol, 2-ethyl-2-butyl-1,3-propanediol and the like can be mentioned. it can.

Among the above diols, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 3-methyl-1,5-pentanediol are more preferable, and 1 , 6-Hexanediol, 3-methyl-1,5-pentanediol is more preferable, and 1,6-hexanediol is particularly preferable.
As the diol compound represented by the above formula (19), one type may be used alone, or two or more types may be used in combination.

The number average molecular weight of the diol compound represented by the above formula (19) is preferably 800 or more and 5000 or less, more preferably 800 or more and 3000 or less, and further preferably 900 or more and 2500 or less.
The diol compound represented by the above formula (20) is 2,2-dimethylolpropionic acid or 2,2-dimethylolbutanoic acid.

The polyurethane of the present embodiment is represented by the above formulas (18), (19) and (20) together with the three types of diol compounds represented by the above formulas (18), (19) and (20). When a low molecular weight polyol other than the three diol compounds is used, for example, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol , 1,6-Hexanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, diethylene glycol, dipropylene glycol, glycerin, and trimethylolpropane can be used. Among these polyols, 1,6-hexanediol and 3-methyl-1,5-pentanediol are more preferable. One of these polyols may be used alone, or two or more thereof may be used in combination.

In the polyurethane of the present embodiment, the ratios of x in the above formula (1), y in the above formula (2), and z in the above formula (3) are the above formulas (18), (19), (20). It can be adjusted by the charging ratio of the diol compound represented by.
The number average molecular weight of the polyurethane of the present embodiment is not particularly limited, but is preferably 10,000 or more and 50,000 or less in consideration of the ease of adjusting the viscosity of the curable composition of the present embodiment described later. It is more preferably 40,000 or more, and further preferably 10,000 or more and 30,000 or less.

When the number average molecular weight is within the above range, the solvent solubility of polyurethane is good and the viscosity of the polyurethane solution is unlikely to increase. Therefore, the curable composition described later is used to manufacture an overcoat film or flexible wiring board described later. It is suitable for use in. Further, the elongation, flexibility, and strength of the cured product and the overcoat film, which will be described later, tend to be good.
The "number average molecular weight" referred to here is a polystyrene-equivalent number average molecular weight measured by gel permeation chromatography (hereinafter referred to as "GPC"). In this specification, unless otherwise specified, the measurement conditions of GPC are as follows.

Device name: HPLC unit HSS-2000 manufactured by JASCO Corporation
Column: Showa Denko Corporation Shodex column LF-804 x 3 (series)
Mobile phase: tetrahydrofuran Flow velocity: 1.0 mL / min
Detector: RI-2031Plus manufactured by JASCO Corporation
Temperature: 40.0 ° C
Sample amount: Sample loop 100 μL
Sample concentration: Approximately 0.1% by mass

The acid value of the polyurethane of the present embodiment is not particularly limited, but is preferably 10 mgKOH / g or more and 70 mgKOH / g or less, more preferably 10 mgKOH / g or more and 50 mgKOH / g or less, and 15 mgKOH / g. It is more preferably 35 mgKOH / g or less.

When the acid value is within the above range, the polyurethane of the present embodiment has sufficient reactivity with the epoxy group. Therefore, in the curable composition described later, the reactivity with other components such as an epoxy compound having two or more epoxy groups in one molecule is unlikely to be insufficient, and thus the heat resistance of the cured product of the curable composition. The cured product of the curable composition does not become too hard and brittle. In addition, it becomes easy to balance the solvent resistance of the overcoat film described later with the warp of the flexible wiring board described later.
In this specification, the acid value of polyurethane is the value of the acid value measured by the potentiometric titration method specified in JIS K0070.

The aromatic ring concentration of the polyurethane of the present embodiment is not particularly limited, but is preferably 0.1 mmol / g or more and 5.0 mmol / g or less, and 0.5 mmol / g or more and 4.5 mmol / g or less. More preferably, it is more preferably 1.0 mmol / g or more and 4.0 mmol / g or less.
When the aromatic ring concentration is within the above range, it becomes easy to balance the solvent resistance of the overcoat film described later and the warp of the flexible wiring board described later.

The aromatic ring concentration means the number (number of moles) of aromatic rings contained in 1 g of the compound. For example, if a polyurethane having a molecular weight of 438.5 as a repeating unit (structural unit) has four aromatic rings (for example, phenyl groups) per repeating unit, the number of repeating units in 1 g of this polyurethane is 2. Since it is .28 mmol, the aromatic ring concentration is 9.12 mmol / g (4 × 2.28 mmol / 1 g).

The type of aromatic ring is not particularly limited as long as it is a cyclic functional group having aromaticity with 3 or more ring members, and for example, a monocyclic aromatic hydrocarbon group such as a phenyl group, a biphenyl group, or a fluorene group. Examples thereof include a polycyclic aromatic hydrocarbon group such as, a condensed ring aromatic hydrocarbon group such as a naphthalene group and an indenyl group, and a heteroaromatic hydrocarbon group such as a pyridyl group.

However, in the case of a functional group having a plurality of cyclic structural parts such as a polycyclic aromatic hydrocarbon group and a fused cyclic aromatic hydrocarbon group, the number of aromatic rings is not one but the number of cyclic structural parts. To do. For example, since a fluorene group has two benzene rings which are cyclic structure sites, in the case of a polyurethane having one fluorene group per repeating unit, the number of aromatic rings possessed by the polyurethane is 1 repeating unit. Two per piece.

Similarly, in the case of a biphenyl group or naphthalene group, the number of aromatic rings is 2, in the case of an anthracene group or phenanthrene group, the number of aromatic rings is 3, and in the case of a triphenylene group or binaphthyl group, the number of aromatic rings is 4. And.
The aromatic ring concentration can be calculated from the charging ratio of the monomers, but can be obtained by ¹ H-NMR analysis after determining the structure of the polyurethane by spectroscopic methods such as ¹ H-NMR, ¹³ C-NMR, and IR. It can also be calculated by comparing the number of protons derived from the aromatic ring with the number of protons derived from one repeating unit using the integration curve.

The polymerization reaction for synthesizing the polyurethane of the present embodiment may be carried out in a solvent, but the type of solvent used as the polymerization solvent when carried out in the solvent is any solvent capable of dissolving the polyurethane of the present embodiment. There is no particular limitation. Examples of the solvent used for synthesizing the polyurethane of the present embodiment include diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol dibutyl ether, diethylene glycol butyl methyl ether, diethylene glycol isopropyl methyl ether, and triethylene glycol dimethyl ether. Ether solvents such as triethylene glycol butyl methyl ether, tetraethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol dimethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol mono Ethyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, methyl methoxypropionate, ethyl methoxypropionate, methyl ethoxypropionate, ethyl ethoxypropionate, Examples thereof include ester solvents such as γ-butyrolactone, hydrocarbon solvents such as decahydronaphthalin, and ketone solvents such as cyclohexanone. One of these solvents may be used alone, or two or more of these solvents may be used in combination.

Among these solvents, γ-butyrolactone, diethylene glycol diethyl ether, diethylene glycol monoethyl ether acetate, and diethylene glycol are considered in consideration of the ease of adjusting the molecular weight of polyurethane and the printability of the curable composition described below during screen printing. Monomethyl ether acetate is preferable, γ-butyrolactone, diethylene glycol monoethyl ether acetate, and diethylene glycol diethyl ether are more preferable, a single solvent of γ-butyrolactone, a mixed solvent of γ-butyrolactone and diethylene glycol monoethyl ether acetate, γ-butyrolactone and diethylene glycol. More preferably, a mixed solvent of 2 types of diethyl ether and a mixed solvent of 3 types of γ-butyrolactone, diethylene glycol monoethyl ether acetate and diethylene glycol diethyl ether are preferable.

The solid content concentration of the polyurethane solution of the present embodiment is not particularly limited, but is preferably 10% by mass or more and 90% by mass or less, more preferably 15% by mass or more and 70% by mass or less, and 20% by mass or more and 60% by mass or less. % Or less is more preferable. When a polyurethane solution having a solid content concentration of 20% by mass or more and 60% by mass or less is used to produce a curable composition described below, the viscosity of the polyurethane solution is determined by the measurement conditions described later in the section of Examples. In, for example, it is preferably 5,000 mPa · s or more and one million mPa · s or less from the viewpoint of uniform dispersion.

Further, the order in which the raw materials such as monomers are charged into the reaction vessel when the polymerization reaction for synthesizing the polyurethane of the present embodiment is carried out is not particularly limited, but may be charged in the following order, for example. That is, three kinds of diol compounds represented by the above formulas (18), (19) and (20), and, if desired, three kinds of diols represented by the above formulas (18), (19) and (20). After dissolving the polyol other than the compound in the solvent in the reaction vessel, the diisocyanate compound OCN-R ^1- NCO is added little by little to the reaction vessel at 30 ° C. or higher and 140 ° C. or lower, preferably 60 ° C. or higher and 120 ° C. or lower. , 50 ° C. or higher and 160 ° C. or lower, preferably 60 ° C. or higher and 150 ° C. or lower, react each of the above monomers to carry out polymerization.

The molar ratio of the monomer charged is adjusted according to the molecular weight, acid value, and the ratio of x, y, and z of the target polyurethane. A monohydroxy compound may be used as a raw material for the polyurethane of the present embodiment in order to adjust the molecular weight of the polyurethane. In that case, when the molecular weight of the polyurethane being polymerized reaches the desired number average molecular weight (or approaches the target number average molecular weight) by the above method, the isocyanato group at the molecular end of the polyurethane being polymerized is sealed. A monohydroxy compound is added for the purpose of stopping and suppressing a further increase in the number average molecular weight.

When a monohydroxy compound is used, the total number of hydroxy groups obtained by subtracting the total number of hydroxy groups of the monohydroxy compound from the total number of hydroxy groups of all the raw materials of polyurethane (that is, two in one molecule which is the raw material of polyurethane). The total number of isocyanato groups contained in all the raw materials of polyurethane may be smaller, the same, or larger than the total number of hydroxy groups contained in the above compounds having hydroxy groups.

When an excess amount of the monohydroxy compound is used, an unreacted monohydroxy compound remains. In this case, the excess monohydroxy compound may be used as it is as a part of the solvent. Alternatively, it may be removed by an operation such as distillation.
The reason why the monohydroxy compound is used as a raw material for polyurethane is to suppress an increase in the molecular weight of the polyurethane of the present embodiment (that is, to stop the polymerization reaction), and to add the monohydroxy compound in the reaction solution at 30 ° C. or higher and 150 ° C. or lower. , Preferably added little by little at 70 ° C. or higher and 140 ° C. or lower, and then held at the above temperature to complete the reaction.

Moreover, in order to adjust the molecular weight of polyurethane, a monoisocyanate compound may be used as a raw material of polyurethane of this embodiment. In that case, the total number of isocyanato groups contained in all the raw materials of polyurethane is used rather than the total number of hydroxy groups contained in all raw materials of polyurethane so that the molecular terminal of the polyurethane at the time of adding the monoisocyanate compound becomes a hydroxy group. It is necessary to reduce the total number of isocyanato groups obtained by subtracting the total number of isocyanato groups contained in the isocyanate compound (that is, the total number of isocyanato groups contained in a compound having two or more isocyanato groups in one molecule which is a raw material of polyurethane).

When the reaction between the hydroxy group of all the raw materials of polyurethane and the isocyanato group of the diisocyanate compound is almost completed, the hydroxy group remaining at the molecular terminal of the polyurethane during production is reacted with the isocyanato group of the monoisocyanate compound. For that purpose, the temperature of the polyurethane solution during polyurethane production is set to 30 ° C. or higher and 150 ° C. or lower, preferably 70 ° C. or higher and 140 ° C. or lower, and then the monoisocyanate compound is added little by little to the polyurethane solution and then maintained at the above temperature. Complete the reaction.

In producing the polyurethane of the present embodiment, the blending amount of each component of the raw material is preferably as follows. The amount of the diol compound represented by the above formula (20) is preferably 1% by mass or more and 20% by mass or less, and 2% by mass or more and 10% by mass, based on the total amount of the total raw materials of the polyurethane of the present embodiment. The following is more preferable.

Further, the ratio of the total number of hydroxy groups contained in the diol compound which is the raw material of the polyurethane of the present embodiment to the total number of isocyanato groups contained in the diisocyanate compound which is the raw material of the polyurethane of the present embodiment is: hydroxy group: isocyanato group = 1. : 0.9 to 0.9: 1, and more preferably hydroxy group: isocyanato group = 1: 0.92 to 0.92: 1.

Further, the amount of the diol compound represented by the above formula (18) is 3% by mass with respect to the total mass of all the raw materials of the polyurethane of the present embodiment minus the total mass of the monohydroxy compound and the monoisocyanate compound. It is preferably 20% by mass or less, and more preferably 5% by mass or more and 15% by mass or less.

The amount of the diol compound represented by the above formula (18) is 3% by mass or more and 20 with respect to the total mass of the total raw materials of the polyurethane of the present embodiment minus the total mass of the monohydroxy compound and the monoisocyanate compound. When it is in the range of mass% or less, it is possible to balance the low warpage property of the flexible wiring board of the present embodiment described later and the disconnection suppressing property of the wiring.

II. Curable Composition The curable composition of the present embodiment comprises the polyurethane (a) of the present embodiment, a solvent (b), and an epoxy compound (c) having two or more epoxy groups in one molecule. It is a composition containing.

(1) Solvent (b)
The type of the solvent (b), which is one of the essential components of the curable composition of the present embodiment, is not particularly limited as long as the polyurethane (a) of the present embodiment can be dissolved. Diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol dibutyl ether, diethylene glycol butyl methyl ether, diethylene glycol isopropyl methyl ether, triethylene glycol dimethyl ether, triethylene glycol butyl methyl ether, tetraethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, tripropylene Examples thereof include ether-based solvents such as glycol dimethyl ether.

Examples of the solvent (b) include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, dipropylene glycol monomethyl ether acetate, and dipropylene glycol monoethyl ether acetate. Examples thereof include ester solvents such as diethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, methyl methoxypropionate, ethyl methoxypropionate, methyl ethoxypropionate, ethyl ethoxypropionate, and γ-butyrolactone.
Further, examples of the solvent (b) include hydrocarbon solvents such as decahydronaphthalene and ketone solvents such as cyclohexanone.
One of these solvents may be used alone, or two or more of these solvents may be used in combination.

Among these solvents, γ-butyrolactone, diethylene glycol diethyl ether, diethylene glycol monoethyl ether acetate and diethylene glycol monomethyl ether acetate are preferable, and γ-butyrolactone and diethylene glycol are preferable in consideration of the balance between printability during screen printing and solvent volatility. More preferably, monoethyl ether acetate and diethylene glycol diethyl ether are a single solvent of γ-butyrolactone, a mixed solvent of γ-butyrolactone and diethylene glycol monoethyl ether acetate, a mixed solvent of γ-butyrolactone and diethylene glycol diethyl ether, and γ-. A three-kind mixed solvent of butyrolactone, diethylene glycol monoethyl ether acetate, and diethylene glycol diethyl ether is more preferable.

A combination of these preferable solvents is suitable because it is excellent as a solvent for screen printing ink.
Further, as a part or all of the solvent (b) contained in the curable composition of the present embodiment, the synthetic solvent used for producing the polyurethane (a) of the present embodiment can be used as it is. This is preferable in terms of process because the curable composition of the present embodiment can be easily produced.

The content of the solvent (b) in the curable composition of the present embodiment is preferably 25% by mass or more and 75% by mass or less, and 35% by mass or more, based on the total amount of the curable composition of the present embodiment. It is more preferably 65% by mass or less. Here, the total amount of the curable composition of the present embodiment is the total amount of the polyurethane (a), the solvent (b), and the epoxy compound (c) having two or more epoxy groups in one molecule. .. However, when the curable composition of the present embodiment contains other components such as fine particles (d) described later, the total amount of the curable composition of the present embodiment is the polyurethane (a) and the solvent. (B), the epoxy compound (c) having two or more epoxy groups in one molecule, and other components such as fine particles (d).

When the content of the solvent (b) is within the range of 25% by mass or more and 75% by mass or less with respect to the total amount of the curable composition of the present embodiment, the viscosity of the curable composition is printed by the screen printing method. The viscosity is good, and the spread of the curable composition after screen printing due to bleeding is not so large. As a result, the phenomenon that the printed area of the curable composition actually printed is larger than the portion to which the curable composition is to be applied (that is, the shape of the printing plate) is less likely to occur, which is preferable.

(2) An epoxy compound having two or more epoxy groups in one molecule (c)
The epoxy compound (c), which is one of the essential components of the curable composition of the present embodiment, reacts with the carboxy group or the hydroxy group of the polyurethane (a) and functions as a curing agent in the curable composition. is there.

The type of the epoxy compound (c) is not particularly limited as long as it is a compound having two or more epoxy groups in one molecule, and examples thereof include a novolak type epoxy resin obtained by epoxidizing a novolak resin. Specific examples of the novolak type epoxy resin include phenol novolac type epoxy resin and orthocresol novolac type epoxy resin.

The novolak resin includes phenols such as phenol, cresol, xylenol, resorcin, and catechol, and / or naphthols such as α-naphthol, β-naphthol, and dihydroxynaphthalene, and formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, and salicylaldehyde. It is a resin obtained by condensing or co-condensing a compound having an aldehyde group such as the above under an acidic catalyst.

Further, examples of the epoxy compound (c) having two or more epoxy groups in one molecule include diglycidyl ethers of phenols and glycidyl ethers of alcohols. Here, examples of the above-mentioned phenols include bisphenol A, bisphenol F, bisphenol S, alkyl-substituted or unsubstituted biphenols, and stillben-based phenols. That is, the diglycidyl ethers of these phenols are bisphenol A type epoxy compound, bisphenol F type epoxy compound, bisphenol S type epoxy compound, biphenyl type epoxy compound, and stillben type epoxy compound. Examples of the alcohol include butanediol, polyethylene glycol, polypropylene glycol and the like.

Further, examples of the epoxy compound (c) having two or more epoxy groups in one molecule include glycidyl ester type epoxy resins of carboxylic acids such as phthalic acid, isophthalic acid and tetrahydrophthalic acid, and aniline and bis (4). -Aminophenyl) Nitrogen of glycidyl-type or methylglycidyl-type epoxy resin, which is a compound in which active hydrogen bonded to a nitrogen atom of methane, isocyanuric acid, etc. is replaced with a glycidyl group, and aminophenols such as p-aminophenol. Examples thereof include glycidyl-type or methylglycidyl-type epoxy resins, which are compounds in which active hydrogen bonded to an atom and active hydrogen of a phenolic hydroxy group are substituted with glycidyl groups, respectively.

Further, examples of the epoxy compound (c) having two or more epoxy groups in one molecule include vinylcyclohexene diepoxide, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 2- (3). , 4-Epoxy) Cyclohexyl-5,5-Spiro (3,4-Epoxy) Cyclohexane-m-dioxane and other alicyclic epoxy resins can be mentioned. These alicyclic epoxy resins are obtained by epoxidizing the olefin bonds of an alicyclic hydrocarbon compound having an olefin bond in the molecule.

Further, examples of the epoxy compound (c) having two or more epoxy groups in one molecule include glycidyl ether of paraxylylene and / or metaxylylene-modified phenolic resin, glycidyl ether of terpene-modified phenolic resin, and dicyclopentadiene-modified phenolic resin. Examples thereof include glycidyl ether of glycidyl ether, glycidyl ether of cyclopentadiene-modified phenol resin, glycidyl ether of polycyclic aromatic ring-modified phenol resin, and glycidyl ether of naphthalene ring-containing phenol resin.

Further, examples of the epoxy compound (c) having two or more epoxy groups in one molecule include a halogenated phenol novolac type epoxy resin, a hydroquinone type epoxy resin, a trimethylol propane type epoxy resin, and a linear aliphatic epoxy resin. (A product obtained by oxidizing an olefin bond of a linear aliphatic hydrocarbon compound having an olefin bond in the molecule with a peracid such as peracetic acid), and a diphenylmethane type epoxy resin can be mentioned.

Further, as the epoxy compound (c) having two or more epoxy groups in one molecule, for example, an epoxidized product of an aralkyl type phenol resin such as a phenol aralkyl resin or a naphthol aralkyl resin, a sulfur atom-containing epoxy resin, or a tricyclo [5.2.1.0 ^2,6 ] Examples thereof include diglycidyl ether of decandimethanol and an epoxy resin having an adamantan structure. Examples of epoxy resins having an adamantane structure include 1,3-bis (1-adamantyl) -4,6-bis (glycidyloyl) benzene, 1- [2', 4'-bis (glycidiroyl) phenyl] adamantane, 1 , 3-Bis (4'-glycidyl phenyl) adamantane, 1,3-bis [2', 4'-bis (glycidyl phenyl) phenyl] adamantane and the like.
One of these epoxy compounds (c) may be used alone, or two or more thereof may be used in combination.

Among these epoxy compounds (c), an epoxy compound having two or more epoxy groups in one molecule and having an aromatic ring structure and / or an alicyclic structure is preferable.
When the long-term insulation performance of the cured product of the present embodiment to be described later is emphasized, a cured product having a low water absorption rate can be obtained. Therefore, one molecule has two or more epoxy groups and has an aromatic ring structure and /. Alternatively, among the epoxy compounds having an alicyclic structure, a compound having two or more epoxy groups in one molecule and having a tricyclodecane structure and an aromatic ring structure is preferable.

Specific examples of the compound having two or more epoxy groups in one molecule and having a tricyclodecane structure and an aromatic ring structure include glycidyl ether of a dicyclopentadiene-modified phenol resin (that is, two or more in one molecule). Compound having an epoxy group of and having a tricyclo [5.2.1.0 ^2,6 ] decane structure and an aromatic ring structure), 1,3-bis (1-adamantyl) -4,6-bis (glycidyloyl) ) Benzene, 1- [2', 4'-bis (glycidylyl) phenyl] adamantane, 1,3-bis (4'-glycidylphenyl) adamantane, and 1,3-bis [2', 4'-bis (Glysidiloyl) phenyl] An epoxy resin having an adamantane structure such as adamantane (that is, having two or more epoxy groups in one molecule and having a tricyclo [3.3.1.1 ^3,7 ] decane structure and aromatic ring structure A compound having the above formula (21) and a compound represented by the following formula (21). Among these, the compound represented by the following formula (21) is particularly preferable. In addition, k in the following formula (21) is an integer of 1 or more, and is preferably an integer of 10 or less.

On the other hand, when the reactivity with polyurethane is emphasized, among the epoxy compounds having two or more epoxy groups in one molecule and having an aromatic ring structure and / or an alicyclic structure, two in one molecule. A compound having the above epoxy group and having an amino group and an aromatic ring structure is preferable.
Specific examples of the compound having two or more epoxy groups in one molecule and having an amino group and an aromatic ring structure include glycidyl as an active hydrogen bonded to a nitrogen atom of aniline and bis (4-aminophenyl) methane. Glycidyl-type or methylglycidyl-type epoxy resin, which is a compound substituted with a group, and glycidyl, which is a compound in which active hydrogen bonded to a nitrogen atom of aminophenols and active hydrogen of a phenolic hydroxy group are each substituted with a glycidyl group. Examples thereof include type or methylglycidyl type epoxy resins and compounds represented by the following formula (22). Among these, the compound represented by the following formula (22) is particularly preferable.

The ratio of the content of the epoxy compound (c) to the total amount of the polyurethane (a) and the epoxy compound (c) in the curable composition of the present embodiment is preferably 1% by mass or more and 60% by mass or less. It is more preferably 2% by mass or more and 50% by mass or less, and further preferably 3% by mass or more and 40% by mass or less. That is, the ratio of the content of the polyurethane (a) to the total amount of the polyurethane (a) and the epoxy compound (c) in the curable composition of the present embodiment is preferably 40% by mass or more and 99% by mass or less. , 50% by mass or more and 98% by mass or less, and more preferably 60% by mass or more and 97% by mass or less.

When the ratio of the content of the epoxy compound (c) to the total amount of the polyurethane (a) and the epoxy compound (c) is 1% by mass or more and 60% by mass or less, the overcoat film described later is coated, which will be described later. It is possible to balance the low warpage of the flexible wiring board and the ability to suppress disconnection of the wiring.

(3) Fine particles (d)
At least one kind of fine particles (d) selected from the group consisting of inorganic fine particles and organic fine particles may be added to the curable composition of the present embodiment. By adding the fine particles (d), the viscosity and thixotropy of the curable composition at the time of printing can be adjusted, and the curable composition (that is, ink) can be suppressed from flowing out.

Examples of the inorganic fine particles include silica (SiO ₂ ), alumina (Al ₂ O ₃ ), titanium (TIO ₂ ), titanium oxide (Ta ₂ O ₅ ), zirconia (ZrO ₂ ), and silicon nitride (Si ₃ N ₄ ). , Barium titanate (BaO · TiO ₂ ), barium carbonate (BaCO ₃ ), lead titanate (PbO · TiO ₂ ), lead zirconate titanate (PZT), lead zirconate titanate, lead lanthanum (PLZT), gallium oxide (Ga ₂ O _3), spinel _{(MgO · Al 2 O 3)} , mullite _{(3Al 2 O 3 · 2SiO 2} ), cordierite _{(2MgO · 2Al 2 O 3 ·} 5SiO 2), talc (3MgO · 4SiO ₂ · H ₂ O), aluminum titanate _{(TiO 2 -Al 2 O 3)} , yttria-containing zirconia _{(Y 2 O 3 -ZrO 2)} , barium silicate (BaO · 8SiO _2), boron nitride (BN), calcium carbonate (CaCO ₃ ), calcium sulfate (CaSO ₄ ), zinc oxide (ZnO), magnesium titanate (MgO / TiO ₂ ), barium sulfate (BaSO ₄ ), organic bentonite, carbon (C), hydrotalcite, etc. May be used alone or in combination of two or more.

As the organic fine particles, fine particles of a heat-resistant resin having an amide bond, an imide bond, an ester bond or an ether bond are preferable. Examples of these resins include polyimide resins or precursors thereof, polyamideimide resins or precursors thereof, or polyamide resins from the viewpoint of heat resistance and mechanical properties.
Among these fine particles, silica fine particles and hydrotalcite fine particles are preferable, and the curable composition of the present embodiment preferably contains at least one selected from silica fine particles and hydrotalcite fine particles.

The silica fine particles used in the curable composition of the present embodiment are in the form of powder, and may be silica fine particles having a coating on the surface or silica fine particles chemically surface-treated with an organic compound.
The silica fine particles used in the curable composition of the present embodiment are not particularly limited as long as they are dispersed in the curable composition to form a paste, but for example, from Nippon Aerosil Co., Ltd. Examples include Aerosil (trade name) provided. Silica fine particles typified by Aerosil (trade name) are sometimes used to impart printability at the time of screen printing to a curable composition, and in that case, they are used for the purpose of imparting tincture. ..

Hydrotalcite particles used in the curable composition of the present embodiment is a kind of clay minerals naturally occurring typified by _{Mg 6 Al 2 (OH) 16} CO 3 · 4H 2 O , etc., a layered It is an inorganic compound. Hydrotalcite can also be obtained synthetically. For example, Mg _1-x Al _x (OH) ₂ (CO ₃ ) _{x / 2} · mH ₂ O and the like can be obtained synthetically. That is, the hydrotalcite is Mg / Al-based layered compound, by ion exchange with carbonate groups in the interlayer, chloride ions immobilized anions (Cl - ^-) and / or sulfate ions (SO ₄₎ it can. Using this feature, chloride ions that cause migration of copper and tin (Cl ^-) and sulfate ions (SO ₄ ^-) to capture, it is possible to improve the long-term insulation reliability of the cured product.

Examples of commercially available hydrotalcite products include STABIACE HT-1, STABIACE HT-7, and STABIACE HT-P of Sakai Chemical Industry Co., Ltd., and DHT-4A, DHT-4A2, and DHT-4C of Kyowa Chemical Industry Co., Ltd. Can be mentioned.
The mass average particle diameter of these inorganic fine particles and organic fine particles is preferably 0.01 to 10 μm, more preferably 0.1 to 5 μm.

The content of the fine particles (d) in the curable composition of the present embodiment is 0.1 mass by mass with respect to the total amount of the polyurethane (a), the solvent (b), the epoxy compound (c) and the fine particles (d). % Or more and 60% by mass or less, more preferably 0.5% by mass or more and 40% by mass or less, and further preferably 1% by mass or more and 20% by mass or less.

When the content of the fine particles (d) in the curable composition of the present embodiment is within the above range, the viscosity of the curable composition is good for printing by the screen printing method, and the screen The spread of the curable composition after printing due to bleeding is not so large. As a result, the phenomenon that the printed area of the curable composition actually printed is larger than the portion to which the curable composition is to be applied (that is, the shape of the printing plate) is less likely to occur, which is preferable.

(4) Curing Accelerator The curing accelerator (e) may be added to the curable composition of the present embodiment. The type of the curing accelerator is not particularly limited as long as it is a compound that promotes the reaction between the carboxy group of the polyurethane (a) and the epoxy group of the epoxy compound (c), and examples thereof include the following compounds. Be done.

That is, examples of the curing accelerator include melamine, acetoguanamine, benzoguanamine, 2,4-diamino-6-methacryloyloxyethyl-s-triazine, 2,4-methacryloyloxyethyl-s-triazine, and 2,4-diamino. Examples thereof include triazine compounds such as -6-vinyl-s-triazine and 2,4-diamino-6-vinyl-s-triazine / isocyanuric acid adduct.

Examples of curing accelerators include imidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1-benzyl-2-methyl. Imidazole, 2-phenyl-4-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-aminoethyl-2-ethyl-4-methylimidazole, 1-amino Ethyl-2-methylimidazole, 1- (cyanoethylaminoethyl) -2-methylimidazole, N- [2- (2-methyl-1-imidazolyl) ethyl] urea, 1-cyanoethyl-2-undecylimidazole, 1- Cyanoethyl-2-methylimidazolium trimerite, 1-cyanoethyl-2-phenylimidazolium trimerite, 1-cyanoethyl-2-ethyl-4-methylimidazolium trimerite, 1-cyanoethyl-2-undecylimidazole Rium trimellitate, 2,4-diamino-6- [2'-methylimidazolyl- (1')]-ethyl-s-triazine, 2,4-diamino-6- [2'-undecylimidazolyl- (1') ')]-Ethyl-s-triazine, 2,4-diamino-6- [2'-ethyl-4'-methylimidazolyl- (1')]-ethyl-s-triazine, 1-dodecyl-2-methyl- 3-benzylimidazolium chloride, N, N'-bis (2-methyl-1-imidazolylethyl) urea, N, N'-bis (2-methyl-1-imidazolylethyl) adipamide, 2-phenyl-4-methyl -5-Hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-methylimidazole / isocyanuric acid adduct, 2-phenylimidazole / isocyanuric acid adduct, 2,4-diamino-6- [2' -Methylimidazolyl- (1')]-ethyl-s-triazine isocyanuric acid adduct, 2-methyl-4-formylimidazole, 2-ethyl-4-methyl-5-formylimidazole, 2-phenyl-4 -Methylformylimidazole, 1-benzyl-2-phenylimidazole, 1,2-dimethylimidazole, 1- (2-hydroxyethyl) imidazole, vinyl imidazole, 1-methylimidazole, 1-allyl imidazole, 2-ethylimidazole, 2-butyl Imidazole, 2-butyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo [1,2-a] benzimidazole, 1-benzyl-2-phenylimidazole hydrogen bromide, 1-dodecyl-2- Examples thereof include imidazole compounds such as methyl-3-benzylimidazolium chloride.

Further, examples of the curing accelerator include cycloamidine compounds such as diazabicycloalkene and salts thereof and derivatives thereof. Examples of the diazabicycloalkene include 1,5-diazabicyclo (4.3.0) nonene-5 and 1,8-diazabicyclo (5.4.0) undecene-7.

Further, as examples of curing accelerators, triphenylphosphine, diphenyl (p-tryl) phosphine, tris (alkylphenyl) phosphine, tris (alkoxyphenyl) phosphine, tris (alkyl alkoxyphenyl) phosphine, tris (dialkylphenyl) Trisphine, tris (trialkylphenyl) phosphine, tris (tetraalkylphenyl) phosphine, tris (dialkoxyphenyl) phosphine, tris (trialkoxyphenyl) phosphine, tris (tetraalkoxyphenyl) phosphine, trialkylphosphine, dialkylarylphosphine, Examples include organic phosphine compounds such as alkyldiarylphosphine.

Further, examples of the curing accelerator include amine compounds such as triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, and tris (dimethylaminomethyl) phenol, and dicyandiazide.
One of these curing accelerators may be used alone, or two or more thereof may be used in combination.

Among these curing accelerators, melamine, imidazole compound, cycloamidine compound and its derivative, phosphine compound, and amine compound are considered in consideration of both the curing promoting action and the electrical insulation performance of the cured product of the present embodiment described later. Is preferable, melamine, 1,5-diazabicyclo (4.3.0) nonen-5 and a salt thereof, 1,8-diazabicyclo (5.4.0) undecene-7 and a salt thereof are more preferable.

The content of the curing accelerator (e) in the curable composition of the present embodiment is not particularly limited as long as the curing promoting effect is exhibited, but the curability and the curable composition of the present embodiment From the viewpoint of the electrical insulation characteristics and water resistance of the cured product and overcoat film of the present embodiment, which will be described later, the total amount of the polyurethane (a) and the epoxy compound (c) is 100 parts by mass, and the curing accelerator (e) is 0. It is preferably blended in the range of 05 parts by mass or more and 5 parts by mass or less, and more preferably in the range of 0.1 parts by mass or more and 3 parts by mass or less.
When the content of the curing accelerator (e) in the curable composition of the present embodiment is within the above range, the curable composition of the present embodiment can be cured in a short time, and the present embodiment will be described later. The cured product in the form and the overcoat film have good electrical insulation characteristics and water resistance.

(5) Other Additives In addition to the fine particles (d) and the curing accelerator (e), various additives may be added to the curable composition of the present embodiment. The additives that can be blended in the curable composition of the present embodiment will be described below.

When the curable composition of the present embodiment is cured, a cured product having good electrical insulation characteristics can be obtained. Therefore, the curable composition of the present embodiment is used, for example, for resist ink for insulating and protecting wiring. It can be used as a composition. When the curable composition of the present embodiment is used as a composition for a resist ink for insulating and protecting wiring (that is, an overcoating agent for a flexible wiring board), the generation of bubbles during printing is prevented or suppressed. For the purpose, the antifoaming agent (f) may be added.

The type of defoaming agent is such that the generation of bubbles can be prevented or suppressed when the curable composition of the present embodiment is printed and applied on the surface of the flexible substrate at the time of manufacturing the flexible wiring board. Although not particularly limited, for example, the following antifoaming agents can be mentioned as examples.
That is, examples of antifoaming agents include BYK-077 (manufactured by Big Chemie Japan Co., Ltd.), SN Deformer 470 (manufactured by Sannopco Co., Ltd.), TSA750S (manufactured by Momentive Performance Materials Co., Ltd.), and silicone oil SH-203 (manufactured by Momentive Performance Materials). Silicone defoamers such as Toray Dow Corning Co., Ltd., Dappo SN-348 (San Nopco Co., Ltd.), Dappo SN-354 (San Nopco Co., Ltd.), Dappo SN-368 (San Nopco Co., Ltd.), Acrylic polymerization system defoamers such as Disparon 230HF (manufactured by Kusumoto Kasei Co., Ltd.), Surfinol DF-110D (manufactured by Nisshin Chemical Industry Co., Ltd.), Surfinol DF-37 (manufactured by Nisshin Chemical Industry Co., Ltd.), etc. Examples thereof include an acetylene diol-based defoaming agent and a fluorine-containing silicone-based defoaming agent such as FA-630.

The content of the defoaming agent (f) in the curable composition of the present embodiment is not particularly limited, but is limited to polyurethane (a), solvent (b), epoxy compound (c), and fine particles (d). ) Is 100 parts by mass, and the defoaming agent (f) is preferably blended in the range of 0.01 part by mass or more and 5 parts by mass or less, and 0.05 parts by mass or more and 4 parts by mass or less. It is more preferable to blend, and it is further preferable to blend in the range of 0.1 parts by mass or more and 3 parts by mass or less.

Further, the curable composition of the present embodiment includes a surfactant such as a leveling agent, phthalocyanine blue, phthalocyanine green, iodin green, disazo yellow, crystal violet, carbon black, naphthalene black, if necessary. And other colorants can be added.

If it is necessary to suppress the oxidative deterioration of polyurethane (a) and discoloration during heating, use an antioxidant such as a phenolic antioxidant, a phosphite-based antioxidant, or a thioether-based antioxidant. It is preferably added to the curable composition of the embodiment.
Further, a flame retardant or a lubricant can be added to the curable composition of the present embodiment, if necessary.

In the curable composition of the present embodiment, a part or all of the components to be blended (that is, polyurethane (a), solvent (b), epoxy compound (c), fine particles (d), etc.) are rolled mill, bead mill, etc. It can be obtained by uniformly kneading and mixing with. When a part of the components to be blended is mixed, the remaining components can be mixed when the curable composition of the present embodiment is actually used.

<Viscosity of curable composition>
The viscosity of the curable composition of the present embodiment at 25 ° C. is preferably 10,000 mPa · s or more and 100,000 mPa · s or less, and more preferably 20,000 mPa · s or more and 60,000 mPa · s or less.

In the present specification, the viscosity of the curable composition of the present embodiment at 25 ° C. is determined by using a cone / plate viscometer (manufactured by Brookfield, model DV-II + Pro, spindle model number CPE-52). This is the viscosity measured 7 minutes after the start of rotation under the condition of a rotation speed of 10 rpm.

<Thixotropy index of curable composition>
When the curable composition of the present embodiment is used as a composition for resist ink for insulating and protecting wiring (that is, an overcoat agent for a flexible wiring board), the printability of the curable composition of the present embodiment is improved. In order to improve the quality, it is preferable that the thixotropy index of the curable composition of the present embodiment is within a certain range.

When the curable composition of the present embodiment is used as an overcoat agent for a flexible wiring board, in order to improve the printability of the curable composition of the present embodiment (for example, printability in screen printing), the present embodiment The thixotropy index of the curable composition of is preferably 1.1 or more, more preferably 1.1 or more and 3.0 or less, and 1.1 or more and 2.5 or less. It is more preferable to have.

When the curable composition of the present embodiment is used as an overcoat agent for a flexible wiring board, if the thixotropy index of the curable composition of the present embodiment is within the range of 1.1 or more and 3.0 or less, printing is performed. Since the curable composition of the present embodiment is difficult to flow and can be maintained in the form of a film having a constant thickness, it is easy to maintain the printed pattern.

Examples of the method for setting the thixotropy index of the curable composition to 1.1 or more include a method of adjusting the thixotropy index using the above-mentioned inorganic fine particles and organic fine particles, a method of adjusting the thixotropy index using a polymer additive, and the like. However, a method of adjusting the thixotropy index using inorganic fine particles or organic fine particles is preferable.

In the present specification, the thixotropy index of the curable composition of the present embodiment is the ratio of the viscosity measured at a rotation speed of 1 rpm at 25 ° C. to the viscosity measured at a rotation speed of 10 rpm at 25 ° C. ([Rotation speed 1 rpm. [Viscosity in the case of] / [Viscosity in the case of a rotation speed of 10 rpm]). These viscosities can be measured using a cone / plate viscometer (Brookfield, model DV-II + Pro, spindle model number CPE-52).

III. Cured product The cured product of the present embodiment is a cured product obtained by curing the curable composition of the present embodiment, has good low warpage and flexibility, and has excellent long-term insulation reliability. .. The method for curing the curable composition of the present embodiment is not particularly limited, and the curable composition can be cured by heat or active energy rays (for example, ultraviolet rays, electron beams, X-rays). Therefore, a polymerization initiator such as a thermal radical generator or a photoradical generator may be added to the curable composition of the present embodiment.

The cured product of this embodiment can be used as an insulating protective film (overcoat film). In particular, the cured product of this embodiment can be used as an insulating protective film for wiring by covering all or part of the wiring of a flexible wiring board such as a chip-on film (COF).

IV. Overcoat film and flexible wiring board and method for manufacturing the overcoat film of the present embodiment is a film containing a cured product of the present embodiment, and can be produced by curing the curable composition of the present embodiment. it can. More specifically, the overcoat film of the present embodiment is formed by forming the curable composition of the present embodiment into a film on all or a part of the surface of the flexible substrate on which the wiring is formed. After the arrangement, it can be produced by curing the film-like curable composition by heating or the like to obtain a film-like cured product. The overcoat film of the present embodiment is suitable as an overcoat film for a flexible wiring board.

In the flexible wiring board of the present embodiment, all or a part of the surface of the flexible substrate on which the wiring is formed is covered with an overcoat film.
The flexible wiring board of the present embodiment can be manufactured from the curable composition of the present embodiment and a flexible substrate. More specifically, in the flexible wiring board of the present embodiment, the curable composition of the present embodiment is formed into a film on all or a part of the surface of the flexible substrate on which the wiring is formed. After the arrangement, it can be produced by curing the film-like curable composition to form an overcoat film. The wiring covered with the overcoat film is preferably tin-plated copper wiring in consideration of antioxidant and economical aspects of the wiring.

An example of the method for manufacturing the overcoat film and the flexible wiring board of the present embodiment will be described below. The overcoat film and the flexible wiring board of the present embodiment can be formed, for example, through the following steps 1, 2, and 3.
(Step 1) A printing step of forming a printing film on the wiring pattern portion by printing the curable composition of the present embodiment on at least a part of the wiring pattern portion of the flexible substrate.
(Step 2) A solvent removing step of evaporating part or all of the solvent in the printing film by placing the printing film obtained in step 1 in an atmosphere of 40 to 100 ° C.
(Step 3) A curing step of forming an overcoat film by curing the printing film obtained in step 1 or the printing film obtained in step 2 by heating at 100 to 170 ° C.

The printing method of the curable composition in step 1 is not particularly limited. For example, the curable composition of the present embodiment is coated on a flexible substrate by a screen printing method, a roll coater method, a spray method, a curtain coater method, or the like. The printing film can be obtained.
Step 2 is an operation performed as needed, and step 3 may be performed immediately after step 1, and the curing reaction and solvent removal may be performed simultaneously in step 3. When step 2, the temperature is preferably 40 ° C. or higher and 100 ° C. or lower, and 60 ° C. or higher and 100 ° C. or lower, in consideration of the evaporation rate of the solvent and the rapid transition to the thermosetting operation. Is more preferable, and it is further preferable that the temperature is 70 ° C. or higher and 90 ° C. or lower. The time for evaporating the solvent in step 3 and step 2 is not particularly limited, but is preferably 10 minutes or more and 120 minutes or less, and more preferably 20 minutes or more and 100 minutes or less.

The thermosetting temperature in step 3 is preferably 105 ° C. or higher and 160 ° C. or lower from the viewpoint of preventing diffusion of the plating layer and imparting low warpage and flexibility suitable as a protective film to the overcoat film. , 110 ° C. or higher and 150 ° C. or lower is more preferable. The thermosetting time performed in the step 3 is not particularly limited, but is preferably 10 minutes or more and 150 minutes or less, and more preferably 15 minutes or more and 120 minutes or less.

By the method as described above, it is possible to obtain a flexible wiring board in which all or a part of the surface of the flexible substrate on which the wiring is formed is covered with an overcoat film. Since the overcoat film thus obtained is excellent in flexibility and flexibility, the flexible wiring board of the present embodiment is also excellent in flexibility and flexibility, and the flexible wiring board is shaken. Even so, it is difficult for wiring to break (excellent in suppressing wiring breaks). Therefore, the flexible wiring board of the present embodiment is less likely to cause cracks, and is suitable for a flexible printed wiring board used in a technique such as chip-on-film (COF).

Further, since the curable composition of the present embodiment is less likely to shrink during curing, the flexible wiring board of the present embodiment has a small warp. Therefore, in the process of mounting the IC chip on the flexible wiring board of the present embodiment, it is easy to align the mounting position of the IC chip. Further, since the overcoat film has excellent long-term insulation reliability, the flexible wiring board of the present embodiment also has excellent long-term insulation reliability.

〔Example〕
Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.
<Synthesis of polyester diol (reference synthesis example)>
983.5 g (6.74 mol) of phthalic anhydride and 879.2 g (7.44 mol) of 1,6-hexanediol were put into a reaction vessel equipped with a stirrer, a thermometer and a condenser with a distillation device, and an oil bath was added. The internal temperature of the reaction vessel was raised to 140 ° C. and stirring was continued for 4 hours. Then, while continuing stirring, 1.74 g of mono-n-butyltin oxide was added.

Then, while gradually raising the internal temperature of the reaction vessel, the pressure inside the reaction vessel was gradually reduced by a vacuum pump, and water was removed from the reaction vessel by vacuum distillation. Finally, the internal temperature was raised to 220 ° C. and the pressure was reduced to 133.32 Pa. After 15 hours, it was confirmed that the water did not completely distill off, and the reaction was terminated.
When the hydroxyl value of the obtained polyester diol was measured, the hydroxyl value was 53.1 mgKOH / g.

<Synthesis of polyurethane>
(Example 1 of Synthesis)
In a reaction vessel equipped with a stirrer, a thermometer and a condenser, polyester diol (Polylite (registered trademark) OD-X-2900 manufactured by DIC Co., Ltd., hydroxyl value 53.4 mgKOH / g, 1,6-hexanediol and anhydrous phthal) 122.1 g of polyester diol made from acid, 12.9 g of 2,2-dimethylol propanoic acid (manufactured by Nippon Kasei Co., Ltd.), which is a carboxy group-containing diol, and diols other than polyester diol and carboxy group-containing diol. 21.4 g of a certain 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene (manufactured by Osaka Gas Chemical Co., Ltd., trade name BPEF) and γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.) 203. 5 g was charged and heated to 100 ° C. to dissolve all the raw materials.

After lowering the temperature of the reaction solution to 90 ° C, 20.9 g of the diisocyanate compound trans-1,4-bis (isocyanatomethyl) cyclohexane (Fortimo (registered trademark) manufactured by Mitsui Chemicals, Inc.) and dicyclohexylmethane-4 , 4'-Diisocyanate (manufactured by Mitsui Chemicals, Inc.) was added dropwise over 30 minutes using a dropping funnel.

After the reaction at 120 ° C. for 8 hours, it was confirmed by infrared spectroscopy (IR) that the absorption due to the C = O expansion and contraction vibration of the isocyanato group was hardly observed. Methylethyloxime (Ube Kosan Co., Ltd.) (Manufactured) 1.7 g was added dropwise to the reaction solution, and the reaction was further carried out at 80 ° C. for 3 hours. Then, after cooling to room temperature, 44.7 g of γ-butyrolactone and 43.8 g of diethylene glycol diethyl ether were added to adjust the handleability. As a result, a solution containing a polyurethane having a carboxy group (hereinafter referred to as "polyurethane solution A1") was obtained.

The viscosity of the obtained polyurethane solution A1 was 133000 mPa · s. Further, the number average molecular weight (Mn) of the polyurethane having a carboxy group contained in the polyurethane solution A1 (hereinafter referred to as “polyurethane AU1”) is 8000, and the weight average molecular weight (Mw) is 74000. The parameter Mz / Mw representing the spread was calculated to be 8.9. The acid value of polyurethane AU1 was 25.0 mgKOH / g. The solid content concentration in the polyurethane solution A1 was 40.5% by mass. The aromatic ring concentration of polyurethane AU1 was 3.21 mmol / g.

Further, the ratios of x in the above formula (1), y in the above formula (2), and z in the above formula (3) to x + y + z were as follows.
x / (x + y + z) = 0.14
y / (x + y + z) = 0.78
z / (x + y + z) = 0.082

(Example 2 of Synthesis)
In a reaction vessel equipped with a stirrer, a thermometer and a condenser, polyester diol (Polylite (registered trademark) OD-X-2900 manufactured by DIC Co., Ltd., hydroxyl value 53.4 mgKOH / g, 1,6-hexanediol and anhydrous phthal) 126.6 g of polyester diol made from acid as a raw material, 13.4 g of 2,2-dimethylol propanoic acid (manufactured by Nippon Kasei Co., Ltd.) which is a carboxy group-containing diol, and diols other than polyester diol and carboxy group-containing diol. 22.1 g of a certain 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene (manufactured by Osaka Gas Chemical Co., Ltd., trade name BPEF) and γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.) 203. 5 g was charged and heated to 100 ° C. to dissolve all the raw materials.

After lowering the temperature of the reaction solution to 90 ° C., 43.4 g of the diisocyanate compound trans-1,4-bis (isocyanatomethyl) cyclohexane (Fortimo (registered trademark) manufactured by Mitsui Chemicals, Inc.) was added in a dropping funnel. It was added dropwise over 30 minutes.
After the reaction at 120 ° C. for 8 hours, it was confirmed by infrared spectroscopy (IR) that the absorption due to the C = O expansion and contraction vibration of the isocyanato group was hardly observed. Methylethyloxime (Ube Kosan Co., Ltd.) (Manufactured) 1.5 g was added dropwise to the reaction solution, and the reaction was further carried out at 80 ° C. for 3 hours. Then, after cooling to room temperature, 44.7 g of γ-butyrolactone and 43.8 g of diethylene glycol diethyl ether were added to adjust the handleability. As a result, a solution containing a polyurethane having a carboxy group (hereinafter referred to as "polyurethane solution A2") was obtained.

The viscosity of the obtained polyurethane solution A2 was 140000 mPa · s. Further, the number average molecular weight (Mn) of the polyurethane having a carboxy group (hereinafter referred to as "polyurethane AU2") contained in the polyurethane solution A2 is 12000, and the weight average molecular weight (Mw) is 92000. The parameter Mz / Mw representing the spread was calculated to be 7.7. The acid value of polyurethane AU2 was 25.0 mgKOH / g. The solid content concentration in the polyurethane solution A2 was 45.2% by mass. The aromatic ring concentration of polyurethane AU2 was 3.33 mmol / g.

Further, the ratios of x in the above formula (1), y in the above formula (2), and z in the above formula (3) to x + y + z were as follows.
x / (x + y + z) = 0.14
y / (x + y + z) = 0.78
z / (x + y + z) = 0.082

(Example 3 of Synthesis)
In a reaction vessel equipped with a stirrer, a thermometer and a condenser, polyester diol (Polylite (registered trademark) OD-X-2900 manufactured by DIC Co., Ltd., hydroxyl value 53.4 mgKOH / g, 1,6-hexanediol and anhydrous phthal) 113.8 g of polyester diol made from acid, 12.9 g of 2,2-dimethylol propanoic acid (manufactured by Nippon Kasei Co., Ltd.), which is a carboxy group-containing diol, and diols other than polyester diol and carboxy group-containing diol. 27.3 g of a certain 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene (manufactured by Osaka Gas Chemical Co., Ltd., trade name BPEF) and γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.) 203. 3 g was charged and heated to 100 ° C. to dissolve all the raw materials.

After lowering the temperature of the reaction solution to 90 ° C., 21.9 g of the diisocyanate compound trans-1,4-bis (isocyanatomethyl) cyclohexane (Fortimo (registered trademark) manufactured by Mitsui Chemicals, Inc.) and dicyclohexylmethane-4 , 4'-Diisocyanate (manufactured by Mitsui Chemicals, Inc.) was added dropwise over 30 minutes using a dropping funnel.

After the reaction at 120 ° C. for 8 hours, it was confirmed by infrared spectroscopy (IR) that the absorption due to the C = O expansion and contraction vibration of the isocyanato group was hardly observed. Methylethyloxime (Ube Kosan Co., Ltd.) 1.9 g was added dropwise to the reaction solution, and the reaction was further carried out at 80 ° C. for 3 hours. Then, after cooling to room temperature, 44.9 g of γ-butyrolactone and 43.8 g of diethylene glycol diethyl ether were added to adjust the handleability. As a result, a solution containing a polyurethane having a carboxy group (hereinafter referred to as "polyurethane solution A3") was obtained.

The viscosity of the obtained polyurethane solution A3 was 161000 mPa · s. Further, the number average molecular weight (Mn) of the polyurethane having a carboxy group contained in the polyurethane solution A3 (hereinafter referred to as “polyurethane AU3”) is 13000, and the weight average molecular weight (Mw) is 119000. The parameter Mz / Mw representing the spread was calculated to be 3.2. The acid value of polyurethane AU3 was 25.1 mgKOH / g. The solid content concentration in the polyurethane solution A3 was 41.1% by mass. The aromatic ring concentration of polyurethane AU3 was 3.87 mmol / g.

Further, the ratios of x in the above formula (1), y in the above formula (2), and z in the above formula (3) to x + y + z were as follows.
x / (x + y + z) = 0.178
y / (x + y + z) = 0.74
z / (x + y + z) = 0.084

(Example 4 of Synthesis)
As diisocyanate compounds, 20.9 g of 1,3-bis (isocyanatomethyl) cyclohexane (Takenate (registered trademark) 600 manufactured by Mitsui Chemicals, Inc.) and dicyclohexylmethane-4,4'-diisocyanate (manufactured by Mitsui Chemicals, Inc.) 28 The reaction was carried out in the same manner as in Example 1 of Synthesis, except that 3 g was used. Then, after cooling to room temperature, 44.7 g of γ-butyrolactone and 43.8 g of diethylene glycol diethyl ether were added to adjust the handleability. As a result, a solution containing a polyurethane having a carboxy group (hereinafter referred to as "polyurethane solution A4") was obtained.

The viscosity of the obtained polyurethane solution A4 was 155,000 mPa · s. Further, the number average molecular weight (Mn) of the polyurethane having a carboxy group (hereinafter referred to as "polyurethane AU4") contained in the polyurethane solution A4 is 12000, and the weight average molecular weight (Mw) is 120,000. The parameter Mz / Mw representing the spread was calculated to be 10.2. The acid value of polyurethane AU4 was 25.0 mgKOH / g. The solid content concentration in the polyurethane solution A4 was 41.7% by mass. The aromatic ring concentration of polyurethane AU4 was 3.21 mmol / g.

Further, the ratios of x in the above formula (1), y in the above formula (2), and z in the above formula (3) to x + y + z were as follows.
x / (x + y + z) = 0.14
y / (x + y + z) = 0.78
z / (x + y + z) = 0.082

(Example 5)
In a reaction vessel equipped with a stirrer, a thermometer and a condenser, polyester diol (Polylite (registered trademark) OD-X-2900 manufactured by DIC Co., Ltd., hydroxyl value 53.4 mgKOH / g, 1,6-hexanediol and anhydrous phthal) 122.3 g of polyester diol made from acid, 12.9 g of 2,2-dimethylol propanoic acid (manufactured by Nippon Kasei Co., Ltd.), which is a carboxy group-containing diol, and diols other than polyester diol and carboxy group-containing diol. 21.4 g of a certain 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene (manufactured by Osaka Gas Chemical Co., Ltd., trade name BPEF) and γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.) 203. 6 g was charged and heated to 100 ° C. to dissolve all the raw materials.

After lowering the temperature of the reaction solution to 90 ° C., 20.5 g of diisocyanate compound 1,3-bis (isocyanatomethyl) benzene (Takenate (registered trademark) 500 manufactured by Mitsui Chemicals, Inc.) and dicyclohexylmethane-4, 28.3 g of 4'-diisocyanate (manufactured by Mitsui Chemicals, Inc.) was added dropwise over 30 minutes using a dropping funnel.

After the reaction at 120 ° C. for 8 hours, it was confirmed by infrared spectroscopy (IR) that the absorption due to the C = O expansion and contraction vibration of the isocyanato group was hardly observed. Methylethyloxime (Ube Kosan Co., Ltd.) (Manufactured) 1.7 g was added dropwise to the reaction solution, and the reaction was further carried out at 80 ° C. for 3 hours. Then, after cooling to room temperature, 44.7 g of γ-butyrolactone and 43.8 g of diethylene glycol diethyl ether were added to adjust the handleability. As a result, a solution containing a polyurethane having a carboxy group (hereinafter referred to as "polyurethane solution A5") was obtained.

The viscosity of the obtained polyurethane solution A5 was 122000 mPa · s. Further, the number average molecular weight (Mn) of the polyurethane having a carboxy group (hereinafter referred to as "polyurethane AU5") contained in the polyurethane solution A5 is 10,000, and the weight average molecular weight (Mw) is 124,000. The parameter Mz / Mw representing the spread was calculated to be 12.0. The acid value of polyurethane AU5 was 25.0 mgKOH / g. The solid content concentration in the polyurethane solution A5 was 42.2% by mass. The aromatic ring concentration of polyurethane AU5 was 4.27 mmol / g.

Further, the ratios of x in the above formula (1), y in the above formula (2), and z in the above formula (3) to x + y + z were as follows.
x / (x + y + z) = 0.14
y / (x + y + z) = 0.78
z / (x + y + z) = 0.082

(Comparative Synthesis Example 1)
65.6 g of methylenebis (4-cyclohexylisocyanate) (Death Module-W (trade name) manufactured by Sumika Bayer Urethane Co., Ltd.) was used as the diisocyanate compound, and ethanol (Wako Jun) was used instead of 1.5 g of methylethyloxime. A solution containing polyurethane having a carboxy group (hereinafter, "" Polyurethane solution B1 ”) was obtained.

The viscosity of the obtained polyurethane solution B1 was 120,000 mPa · s. Further, the number average molecular weight (Mn) of the polyurethane having a carboxy group contained in the polyurethane solution B1 (hereinafter referred to as “polyurethane BU1”) is 14,000, and the weight average molecular weight (Mw) is 104000. The parameter Mz / Mw representing the spread was calculated to be 7.25. The acid value of polyurethane BU1 was 25.0 mgKOH / g. The solid content concentration in the polyurethane solution B1 was 39.6% by mass. The aromatic ring concentration of polyurethane BU1 was 3.10 mmol / g.

(Comparative Synthesis Example 2)
Except for the fact that 64.14 g of methylenebis (4,1-phenylene) diisocyanate (manufactured by Mitsui Chemicals, Inc.) was used as the diisocyanate compound, the reaction and handleability were adjusted in the same manner as in Comparative Synthesis Example 1 to have a carboxy group. A solution containing polyurethane (hereinafter referred to as "polyurethane solution B2") was obtained.

The viscosity of the obtained polyurethane solution B2 was 152000 mPa · s. Further, the number average molecular weight (Mn) of the polyurethane having a carboxy group contained in the polyurethane solution B2 (hereinafter referred to as "polyurethane BU2") is 16000, and the weight average molecular weight (Mw) is 120,000. The parameter Mz / Mw representing the spread was calculated to be 7.8. The acid value of polyurethane BU2 was 25.0 mgKOH / g. The solid content concentration in the polyurethane solution B2 was 40.2% by mass. The aromatic ring concentration of polyurethane BU2 was 7.20 mmol / g.

(Comparative Synthesis Example 3)
Except for the fact that 38.7 g of hexamethylene diisocyanate (Duranate HDI (trade name) manufactured by Asahi Kasei Corporation) was used as the diisocyanate compound, the reaction and handleability were adjusted in the same manner as in Comparative Synthesis Example 1 to have a carboxy group. A solution containing polyurethane (hereinafter referred to as "polyurethane solution B3") was obtained.

The viscosity of the obtained polyurethane solution B3 was 110,000 mPa · s. Further, the number average molecular weight (Mn) of the polyurethane having a carboxy group contained in the polyurethane solution B3 (hereinafter referred to as “polyurethane BU3”) is 15,000, and the weight average molecular weight (Mw) is 115,000. The parameter Mz / Mw representing the spread was calculated to be 9.20. The acid value of polyurethane BU3 was 25.2 mgKOH / g. The solid content concentration in the polyurethane solution B3 was 41.5% by mass. The aromatic ring concentration of polyurethane BU3 was 3.01 mmol / g.

(Measurement of acid value)
A method for measuring the acid value of the synthesized polyurethane will be described. The solvent in the polyurethane solution was distilled off under reduced pressure under heating to obtain polyurethane, and the acid value was measured according to the potentiometric titration method specified in JIS K0070. For the measurement of the acid value by the potentiometric titration method, for example, a potentiometric titration device AT-510 manufactured by Kyoto Denshi Kogyo Co., Ltd. and a composite glass electrode C-173 can be used.

(Measurement of number average molecular weight and weight average molecular weight of polyurethane)
The number average molecular weight and weight average molecular weight of polyurethane are polystyrene-equivalent number average molecular weight and weight average molecular weight measured by GPC. The measurement conditions of GPC are as described above.

(Measurement of viscosity of polyurethane solution)
The viscosity of the polyurethane solution was measured using a cone / plate viscometer (manufactured by Brookfield, model DV-II + Pro, spindle model number CPE-52) under the conditions of a temperature of 25.0 ° C. and a rotation speed of 5 rpm. The measured value is the viscosity measured 7 minutes after the start of rotation of the spindle. Moreover, in the measurement of the viscosity, about 0.8 g of the polyurethane solution was used.

<Manufacturing of main ingredient formulation>
160.0 parts by mass of polyurethane solution A1 with γ-butyrolactone added to adjust the solid content concentration to 40% by mass, and 6.3 parts by mass of silica fine particles (manufactured by Nippon Aerosil Co., Ltd., trade name Aerosil R-974). , 0.72 parts by mass of melamine (manufactured by Nissan Chemical Industries, Ltd.) and 8.4 parts by mass of diethylene glycol diethyl ether, which are curing accelerators, in a three-roll mill (manufactured by Inoue Seisakusho Co., Ltd., model S-4 3 / 4 × 11) was used for mixing. To this, 2.0 parts by mass of an antifoaming agent (manufactured by Momentive Performance Materials, trade name TSA750S) was added and mixed with a spatula to obtain a main agent formulation C1 (see Table 1). ).

In the same manner as in the main agent formulation C1, the polyurethane solutions A2 to A5 and B1 to B3 and the above other components are mixed according to the formulation composition shown in Table 1, and the main agent formulations C2 to C5 and D1 to D3 are mixed, respectively. Obtained. The numerical values in Table 1 represent "parts by mass".

<Manufacturing of curing agent solution>
In a container equipped with a stirrer, a thermometer and a condenser, 16.85 parts by mass of an epoxy compound represented by the above formula (22) (manufactured by Mitsubishi Chemical Corporation, grade name JER604, epoxy equivalent 120 g / eqv) and diethylene glycol diethyl ether After adding 18.25 parts by mass and raising the internal temperature of the container to 40 ° C. while stirring, stirring was continued for 30 minutes. After confirming that the epoxy compound was completely dissolved, the mixture was cooled to room temperature to obtain an epoxy compound solution having a concentration of 48% by mass. This epoxy compound solution is referred to as a curing agent solution E.

<Manufacturing of curable composition>
90 parts by mass of the main agent formulation C1 and 4.0 parts by mass of the curing agent solution E were placed in a plastic container, and 5.0 parts by mass of diethylene glycol diethyl ether and 1.5 parts by mass of diethylene glycol ethyl ether acetate were added as solvents. .. The mixture was stirred at room temperature for 5 minutes using a spatula to obtain a curable composition F1. The viscosity of the curable composition F1 at 25 ° C. was 35,000 mPa · s.

The viscosity of the curable composition was measured using a cone / plate viscometer (manufactured by Brookfield, model DV-II + Pro, spindle model number CPE-52) at a temperature of 25.0 ° C. and a rotation speed of 10 rpm. This measured value is the viscosity measured 7 minutes after the start of rotation of the spindle. Moreover, in the measurement of the viscosity, about 0.6 g of the curable composition was used.
Curable compositions F2 to F5 and G1 to G3 in the same manner as in the case of the curable composition F1, except that any of the main agent formulations C2 to C5 and D1 to D3 is used instead of the main agent formulation C1. (See Table 2).

<Evaluation of overcoat film and flexible wiring board>
Flexible wiring boards having an overcoat film (Examples 1 to 5 and Comparative Examples 1 to 3) were produced by using the curable compositions F1 to F5 and G1 to G3, and the flexibility and wire breakage inhibitory property were obtained. Warpage and long-term insulation reliability were evaluated.

(Evaluation of flexibility)
Flexible copper-clad laminate (manufactured by Sumitomo Metal Mining Co., Ltd., grade name: Esperflex, copper thickness 8 μm, polyimide thickness 38 μm) on copper with a width of 75 mm and a length of 110 mm, and the thickness after curing. The curable composition was applied by screen printing so that the size was 15 μm. The flexible copper-clad laminate on which the curable composition was printed was held at room temperature for 10 minutes and then placed in a hot air circulation dryer at a temperature of 120 ° C. for 60 minutes to cure the curable composition.

After peeling off the PET film lining the flexible copper-clad laminate, it was cut out with a cutter knife to prepare a strip-shaped test piece having a width of 10 mm. The test piece was bent about 180 degrees so that the surface on which the film of the cured product was formed was on the outside, and compressed at a pressure of 0.5 ± 0.2 MPa for 3 seconds using a compressor. Then, with the bent portion of the test piece bent, the film of the cured product was observed at a magnification of 30 times using a microscope to confirm the presence or absence of cracks. The results are shown in Table 3.

(Evaluation of wiring disconnection suppression)
Flexible copper-covered laminated board (manufactured by Sumitomo Metal Mining Co., Ltd., grade name: Esperflex US, copper thickness 8 μm, polyimide thickness 38 μm) is etched and JPCA- is a standard of the Japan Electronic Circuit Industry Association (JPCA). A substrate having a fine comb-shaped pattern as described in ET01 (copper wiring width / copper wiring spacing = 15 μm / 15 μm) was used, and the substrate having a fine comb-shaped pattern was tin-plated to produce a flexible wiring board.

Next, the curable composition was applied onto the flexible wiring board by a screen printing method. The thickness of the film of the printed curable composition was set so that the thickness of the film of the curable composition on the polyimide surface after drying was 10 μm.
The flexible wiring board thus obtained was placed in a hot air circulation dryer having a temperature of 80 ° C. for 30 minutes, and then placed in a hot air circulation dryer having a temperature of 120 ° C. for 120 minutes to cure the flexible wiring board formed on the flexible wiring board. The film of the sex composition was cured. Then, using this test piece, a MIT test was performed by the method described in JIS C5016 to evaluate the disconnection inhibitory property of the wiring of the flexible wiring board. The test conditions for the MIT test are as follows.

Testing machine: MIT tester BE202 manufactured by Tester Sangyo Co., Ltd.
Bending speed: 10 times / minute Load: 200 g
Bending angle: ± 90 °
Radius of the tip of the grip: 0.5 mm
A MIT test was conducted under the above test conditions, and the presence or absence of cracks in the wiring was visually observed every 10 bends, and the wire breakage inhibitory property was evaluated by the number of bends in which the cracks occurred. The results are shown in Table 3.

(Evaluation of warpage)
Screen printing was performed using a # 180 mesh polyester printing plate, and a curable composition was coated on a polyimide base material (Kapton (registered trademark) 100EN manufactured by Toray DuPont Co., Ltd., thickness 25 μm).

The substrate coated with the curable composition thus obtained is placed in a hot air circulation dryer at a temperature of 80 ° C. for 30 minutes, and then placed in a hot air circulation dryer at a temperature of 120 ° C. for 60 minutes. The film of the curable composition formed on the substrate was cured.
The base material having the cured product film was cut with a circle cutter to obtain a circular base material having a cured product film and having a diameter of 50 mm (hereinafter referred to as “substrate”). The obtained substrate exhibits a deformation in which the vicinity of the center warps in a convex or concave shape.

After the substrate is left at 23 ° C. for 1 hour, the substrate is placed on a flat plate in a downwardly convex state. That is, the convex portion near the center of the warped substrate is placed on the flat plate with the convex portion facing downward so that the convex portion of the warped substrate is in contact with the horizontal plane of the flat plate. Then, the distance of the portion of the peripheral edge of the warped substrate farthest from the horizontal plane of the flat plate and the distance of the closest portion were measured, the average value was obtained, and the warpage property was evaluated by this average value. The results are shown in Table 3.
The numerical values shown in Table 3 indicate the direction of warpage. When the substrate is allowed to stand in a downwardly convex state, if the cured product film is on the upper side with respect to the polyimide base material, it is "+", and on the lower side. If it becomes, it is set to "-". Then, the case where the size of the warp was more than -3.0 mm + less than 3.0 mm was regarded as acceptable.

(Evaluation of long-term insulation reliability)
Flexible copper-covered laminated board (manufactured by Sumitomo Metal Mining Co., Ltd., grade name: Esperflex US, copper thickness 8 μm, polyimide thickness 38 μm) is etched and JPCA- is a standard of the Japan Electronic Circuit Industry Association (JPCA). A substrate having a fine comb-shaped pattern as described in ET01 (copper wiring width / copper wiring spacing = 15 μm / 15 μm) was used, and the substrate having a fine comb-shaped pattern was tin-plated to produce a flexible wiring board.

Next, the curable composition was applied onto the flexible wiring board by a screen printing method. The thickness of the film of the printed curable composition was set so that the thickness of the film of the curable composition on the polyimide surface after drying was 15 μm.
The flexible wiring board thus obtained was placed in a hot air circulation dryer having a temperature of 80 ° C. for 30 minutes, and then placed in a hot air circulation dryer having a temperature of 120 ° C. for 120 minutes to cure the flexible wiring board formed on the flexible wiring board. The film of the sex composition was cured.

Then, a bias voltage of 60 V was applied to this test piece using a MIGRATION TESTER MODEL MIG-8600 manufactured by IMV, and a constant temperature / humidity test was conducted under the conditions of a temperature of 120 ° C. and a humidity of 85% RH.
The resistance values of the flexible wiring boards were measured at the initial stage of the constant temperature and humidity test, 100 hours after the start, 250 hours, and 400 hours after the start. The results are shown in Table 3.

As can be seen from the results in Table 3, the flexible wiring board having an overcoat film made of the cured product of the curable compositions F1 to F5 (Examples 1 to 5) is made of the cured product of the curable compositions G1 to G3. A flexible wiring board having an overcoat film made of a cured product of the curable compositions G1 to G3 and having excellent low warpage as compared with a flexible wiring board having an overcoat film (Comparative Examples 1 to 3) (Comparative Example). It had the same or higher flexibility as 1 to 3), the ability to suppress disconnection of wiring, and the long-term insulation reliability.

Therefore, the film made of the cured product of the curable compositions F1 to F5 is useful as an insulating protective film for a flexible wiring board. In particular, the flexible wiring board (Examples 1 to 5) having an overcoat film made of a cured product of the curable compositions F1 to F5 has excellent low warpage, so that the processability is improved in the printing process and the curing process. .. For example, in the mounting process of mounting the IC chip on the flexible wiring board, the alignment accuracy of the mounting position of the IC chip is improved, so that the yield in the manufacturing process is increased.

Claims (16)

It has a first urethane structural unit represented by the following formula (1), a second urethane structural unit represented by the following formula (2), and a third urethane structural unit represented by the following formula (3). And
X number of R ¹ in formula (1) are each independently, 1,3-phenylene methylene group represented by the following formula (4) is represented by the following formula (5) 1,3 It represents a cyclohexanedimethylene group or a trans-type 1,4-cyclohexanedimethylene group represented by the following formula (6), and x is an integer of 1 or more.
Y-number of R ¹ in formula (2) are each independently, 1,3-phenylene methylene group represented by the following formula (4) is represented by the following formula (5) 1,3 cyclohexane dimethylene group, or a trans type 1,4cyclohexanedimethylene group represented by the following formula (6), (n × y ) number of R ² is 6 to 14 carbon atoms each independently represents a divalent organic group, [(n + 1) × y] number of R ³ each independently represents a divalent hydrocarbon group having 3 to 9 carbon atoms, the y-number of n, each independently It is an integer of 0 or more and 50 or less, however, y n is not all 0, and y is an integer of 1 or more.
Z number of R ¹ of formula (3) in each independently, 1,3-phenylene methylene group represented by the following formula (4) is represented by the following formula (5) 1,3 cyclohexane dimethylene group, or a trans type 1,4cyclohexanedimethylene group represented by the following formula (6), z number of R ⁴ each independently represents a methyl group or an ethyl group, z is Polyurethane that is an integer greater than or equal to 1.

The polyurethane according to claim 1, wherein the ratios of x in the formula (1), y in the formula (2), and z in the formula (3) to x + y + z satisfy the following conditions, respectively.
0.01 ≤ x / (x + y + z) ≤ 0.4
0.1 ≤ y / (x + y + z) ≤ 0.9
0.01 ≤ z / (x + y + z) ≤ 0.4 The polyurethane according to claim 1 or 2, wherein the number average molecular weight is 10,000 or more and 50,000 or less. The polyurethane according to any one of claims 1 to 3, which has an acid value of 10 mgKOH / g or more and 70 mgKOH / g or less. The polyurethane according to any one of claims 1 to 4, wherein the aromatic ring concentration is 0.1 mmol / g or more and 5.0 mmol / g or less. A curable composition containing the polyurethane (a) according to any one of claims 1 to 5, the solvent (b), and the epoxy compound (c) having two or more epoxy groups in one molecule. Stuff. The ratio of the content of the solvent (b) to the total amount of the polyurethane (a), the solvent (b) and the epoxy compound (c) is 25% by mass or more and 75% by mass or less, and the polyurethane (a) and the above. The ratio of the content of the polyurethane (a) to the total amount of the epoxy compound (c) is 40% by mass or more and 99% by mass or less, and the epoxy with respect to the total amount of the polyurethane (a) and the epoxy compound (c). The curable composition according to claim 6, wherein the content ratio of the compound (c) is 1% by mass or more and 60% by mass or less. The curable composition according to claim 6 or 7, further comprising at least one fine particle (d) selected from the group consisting of inorganic fine particles and organic fine particles. The curable composition according to claim 8, wherein the fine particles (d) contain silica fine particles. The curable composition according to claim 8, wherein the fine particles (d) contain hydrotalcite fine particles. The ratio of the content of the solvent (b) to the total amount of the polyurethane (a), the solvent (b), the epoxy compound (c) and the fine particles (d) is 25% by mass or more and 75% by mass or less, and the fine particles. The ratio of the content of (d) is 0.1% by mass or more and 60% by mass or less.
The ratio of the content of the polyurethane (a) to the total amount of the polyurethane (a) and the epoxy compound (c) is 40% by mass or more and 99% by mass or less, and the ratio of the content of the epoxy compound (c) is 1% by mass. The curable composition according to any one of claims 8 to 10, which is% or more and 60% by mass or less. A cured product of the curable composition according to any one of claims 6 to 11. An overcoat film containing the cured product according to claim 12. The flexible wiring board in which the portion of the surface of the flexible substrate on which the wiring is formed is covered with the overcoat film according to claim 13. The flexible wiring board according to claim 14, wherein the wiring is tin-plated copper wiring. After the curable composition according to any one of claims 6 to 11 is arranged in a film shape on the portion of the surface of the flexible substrate on which the wiring is formed, the coating is formed. A method for manufacturing a flexible wiring board in which a curable composition is cured to form an overcoat film.