JP2003012794A - Thermally curable resin composition and cured product thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a thermally curable oxetane resin composition having excellent fast curability. SOLUTION: The thermally curable oxetane resin composition comprises (a) a compound represented by formula (1) (wherein (n) is an integer of 2 or more; R is an n-valent organic group; R1 is H or a monovalent alkyl: n R1 s may be identical or different), (b) a curing agent, (c) a curing catalyst as essential components. As the curing agent (b), is cited at least one selected from the group consisting of compounds bearing 2 or more carboxyl groups and compounds bearing one or more acid anhydride groups in one molecule. As the curing catalyst (c), is cited at least one selected from the group consisting of Lewis acids and organic boron compounds represented by formula (2) (wherein D is a divalent organic group).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a thermosetting oxetane resin composition and a cured product thereof.

[0002]

2. Description of the Related Art For photo / thermosetting oxetane resins using cationic curing agents, hard coat agents for the surface of articles,
It is being actively researched in the fields of photocurable adhesives and casting resins.

Japanese Unexamined Patent Publication (Kokai) No. 11-209599 describes a casting resin which comprises a compound having an oxetane ring and a cationic photopolymerization initiator and is useful for sealing optical elements and the like. Further, JP-A-8-85775 describes a resin composition suitable for surface coating of steel sheet, which comprises a compound having 1 to 4 oxetane rings and a photocationic polymerization initiator. However, such a cation-curable resin is a resin obtained by homopolymerizing an oxetane compound or by copolymerizing with an epoxy resin, and like a normal epoxy resin composition, a curing agent is added for imparting properties. It has the drawback that it cannot be used together. In addition, the high cost of the oxetane compound prevents the generalization of thermosetting resins by the cationic curing of oxetane.

On the other hand, it is known that oxetane reacts with various protic compounds, and Nishikubo et al. Have studied the polymerization of a phenol curing agent and an oxetane compound.
urnal of Polymer Science, Part A; Polymer Chemistr
y, vol.37, 2782-2790 (1999)) has been announced. It is disclosed that a bifunctional phenol and a bifunctional oxetane compound cause gelation under a specific catalyst.

Further, it is known that an oxetane compound undergoes polyaddition with a carboxylic acid and then undergoes a polycondensation reaction. In JP-A No. 11-43540, 1 to 1 is included in the molecule.
A technique is disclosed in which a thermosetting resin is obtained by adding a quaternary onium salt as a curing accelerator to a compound having four oxetane rings and a compound having a carboxyl group. However, the oxetane resin composition using these quaternary onium salts has a very slow curing rate and requires a high temperature for curing, or otherwise requires a long time for curing, and therefore, as a thermosetting resin. Was not very practical.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermosetting oxetane resin composition excellent in fast curability and a cured product obtained therefrom.

[0007]

DISCLOSURE OF THE INVENTION In view of the present situation of thermosetting oxetane resins, the inventors of the present invention have made earnest studies and as a result, as a result of using oxetane compounds, carboxylic acids, and a specific curing catalyst, curing We have succeeded in obtaining a resin composition that exhibits various properties depending on the type of agent and has a curing rate that can be sufficiently put to practical use.

That is, in the present invention, the compound (a) represented by the general formula (1), the curing agent (b), and the curing catalyst (c) are essential components, and two curing agents (b) are contained in the molecule. At least one selected from the group consisting of the above compounds having a carboxyl group and compounds having one or more acid anhydride groups in the molecule.
And the curing catalyst (c) is at least one selected from the group consisting of a Lewis acid and an organic boron compound represented by the general formula (2). A curable resin composition and a thermosetting resin cured product obtained by heating and curing the curable resin composition.

[0009]

[Chemical 4] In the formula, n represents an integer of 2 or more, R represents an n-valent organic group, and R represents
₁ is a monovalent alkyl group or hydrogen, and n R _{1 s in} one molecule may be the same or different.

[0010]

[Chemical 5] In the formula, D represents a divalent organic group.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION As the compound (a) represented by the general formula (1) used in the present invention, conventionally known compounds can be used. For example, 1,4-bis [{(3-ethyl-3-oxetanyl) methoxy} methyl] benzene (XDO), di [1-ethyl (3-oxetanyl)] methyl ether (DOX), 9,9-bis [ 2-Methyl-4- {2- (3-oxetanyl)} butoxyphenyl] fluorene, 9,9-bis [4- [2-
Examples include bifunctional oxetane compounds such as {2- (3-oxetanyl)} butoxy] ethoxyphenyl] fluorene, and polyfunctional oxetane compounds such as oxetanized novolac resins. These compounds are readily available on the market.

The hardener (b) used in the present invention is at least one selected from the group consisting of compounds having two or more carboxyl groups in the molecule and compounds having one or more acid anhydride groups in the molecule. Be done. As such compounds, conventionally known compounds can be used, and specifically, dibasic acids such as maleic acid, fumaric acid, hexahydrophthalic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, adipic acid and oxalic acid. , Tribasic acids such as trimellitic acid, tetrabasic acids such as pyromellitic acid, polycarboxylic acids having 5 or more carboxylic acid groups in one molecule such as polyacrylic acid derivatives, and their anhydrides. Examples thereof include, but are not limited thereto, and the kind thereof is not limited as long as it is a compound having a carboxyl group or a carboxylic acid anhydride group reactive with an oxetane compound.

When a carboxylic acid anhydride is used, the composition and composition are determined so that one acid anhydride group corresponds to two carboxyl groups. Two or more carboxyl groups in the curing agent (b) are contained in one molecule, and three or more carboxyl groups are preferably contained in order to improve the crosslink density. As a combination of the compound (a) and the curing agent (b), in consideration of availability, the bifunctional compound (a) and the curing agent (b) having three or more carboxyl groups in one molecule are used. ) Is the best combination.

The compounding ratio of the compound (a) and the curing agent (b) is such that one oxetane ring of the compound (a) has 1.5 to 2.5 carboxyl groups of the curing agent (b). It is preferable to mix them in a ratio of 1.8 to 2.2. If the amount of the carboxyl groups is below this range, a dense crosslinked structure cannot be obtained, and the heat resistance of the cured resin may decrease. On the other hand, if the amount exceeds this range, unreacted groups are generated, which may adversely affect properties such as water absorption of the resin.

In order for the resin composition of the present invention to exhibit excellent fast curing properties, it is essential to use the curing catalyst (c). The curing catalyst is a compound that accelerates the reaction between the compound (a) and the curing agent (b), and is selected from a Lewis acid and an organic boron compound represented by the general formula (2). Here, a Lewis acid is a compound as defined by GN Lewis, and all acids included in this definition are included in the technical scope of the present invention. The organic boron compound represented by the general formula (2) includes diglycerin borate and di (2,3-dihydroxynaphthalene).
Boron chelate compounds such as borates may be mentioned.

[0016]

[Chemical 6] In the formula, D represents a divalent organic group.

Among the Lewis acids, more preferable ones are Lewis acids containing at least one element selected from the group consisting of boron, aluminum, titanium, zinc, tin, and rare earths, and boron is also preferable. The Lewis acid contained is preferably an organic boron compound represented by the general formula (3). As these curing catalysts,
Specifically, a Lewis acid containing an aluminum element such as aluminum chloride, aluminum phenoxide, and aluminum laurate, a Lewis acid containing a zinc element such as zinc chloride, stannous chloride, stannous bromide, and 2-ethylhexyl acid. Lewis acid containing tin element such as tin, triethyl borate,
Triisopropyl borate, tri-n-butyl borate,
Examples thereof include boric acid esters such as triphenyl borate, but boric acid esters are most preferable in consideration of easy availability.

[0018]

[Chemical 7] In the formula, R _{2 to} R ₄ are monovalent groups selected from an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a carboxyl group, a halogen, and hydrogen, and they may be the same or different. May be.

The amount of the curing catalyst (c) used in the present invention is preferably 0.01 to 10 parts by weight based on 100 parts by weight of the compound (a) and the curing agent (b). However, if the characteristics of the resin composition of the present invention are not impaired, there is no problem even if it is out of this range.

In the thermosetting resin composition of the present invention, a coupling agent, a releasing agent, a lubricant, a filler, an antioxidant, etc. within a range not affecting the properties, if necessary, are known to those skilled in the art. It does not matter at all to combine additives and auxiliary materials.

The method for producing the resin composition of the present invention includes:
A general method of mixing each component and heating and kneading with equipment such as a heating kneader and a heating roll can be applied.

[0022]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

(Examples 1 to 6 and Comparative Examples 1 to 4) The compound (a), the compound (b, the curing agent), and the compound (c, the curing catalyst) were mixed at the mixing ratio shown in Table 1 at 120 ° C. The mixture was heated and mixed with, and cooled to obtain a resin composition. To evaluate the characteristics, the gelation time of each resin composition was measured by the following method. The measurement results are summarized in Table 1.

[Measurement of Gelation Time] 1 g of a resin composition prepared in advance was weighed out, spread on a hot plate of 175 ° C., and the molten resin was gelled while stirring with a metal spatula, so that the metal spatula could be easily The time until peeling was measured was taken as the gel time. At this time, those in which gelation was not observed by 30 minutes were described as 30 minutes or longer.

[0025]

[Table 1]

In the table, (Note 1) is 1,4-made by Toagosei.
Bis [{(3-ethyl-3-oxetanyl) methoxy}
Methyl] benzene (oxetane equivalent 179), (Note 2)
Is manufactured by Toagosei, di [1-ethyl (3-oxetanyl)] methyl ether (oxetane equivalent 107), (Note 3) is a bifunctional carboxylic acid (carboxyl equivalent 83),
(Note 4) is a trifunctional carboxylic acid (carboxylic xyl equivalent 7
0) and (Note 5) are polyacrylic acid having a number average molecular weight of 5000 (carboxyl equivalent 72).

As is clear from the gel time measurement results shown in Table 1, the curing catalyst (c) according to the present invention was used as compared with the case where no curing catalyst was added and the comparative example using a conventional curing catalyst. In addition, the thermosetting resin compositions of the present invention (Examples 1 to 6) can exhibit extremely excellent fast curability.

[0028]

INDUSTRIAL APPLICABILITY The thermosetting resin composition according to the present invention can exhibit various properties depending on the type of the curing agent by using a specific curing catalyst for the oxetane compound and the carboxylic acid curing agent. The present invention also provides a new thermosetting oxetane resin composition having a curing rate that can be sufficiently put to practical use.

Claims (4)

[Claims] 1. A compound (a) represented by the general formula (1),
A curing agent (b) and a curing catalyst (c) as essential components,
The curing agent (b) is at least one selected from the group consisting of a compound having two or more carboxyl groups in the molecule and a compound having one or more acid anhydride groups in the molecule, and A thermosetting resin composition, wherein the curing catalyst (c) is at least one selected from the group consisting of a Lewis acid and an organic boron compound represented by the general formula (2). [Chemical 1] In the formula, n represents an integer of 2 or more, R represents an n-valent organic group, and R represents
₁ is a monovalent alkyl group or hydrogen, and n R _{1 s in} one molecule may be the same or different. [Chemical 2] In the formula, D represents a divalent organic group. 2. The thermosetting resin composition according to claim 1, wherein the Lewis acid contains at least one element selected from the group consisting of boron, aluminum, titanium, zinc, tin, and rare earths. object. 3. A Lewis acid containing boron is represented by the general formula (3):
Is an organic boron compound represented by,
The thermosetting resin composition according to claim 2. [Chemical 3] In the formula, R _{2 to} R ₄ are monovalent groups selected from an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a carboxyl group, a halogen, and hydrogen, and they may be the same or different. May be. 4. A cured thermosetting resin, which is obtained by heating and curing the thermosetting resin composition according to any one of claims 1 to 3.