JPH11116682A - Photo-cation curable resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition capable of arbitrarily controlling the physical properties of cured products, capable of forming cured products excellent e.g. in balance between surface hardness and elasticity and useful for coating materials and the like by adding a silsesquioxane preferably having an oxetanyl group. SOLUTION: This composition comprises (A) a photo-cation-polymerizable silsesquioxane compound (e.g. having a number-average mol.wt. of 600-5,000) obtained by hydrolyzing a compound of formula I [R<1> is an oxetanyl-having organic functional group such as a group of formula II (R<1> is H, a 1-6C alkyl; R<2> is a 2-6C alkenylene); X is a hydrolyzable group such as a (cyclo)alkoxy or an aryloxy group, (B) a photo-cation polymerizable compound except the component A, and (C) a cationic photopolymerization initiator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cationic photocurable resin composition, and more particularly, to a cationic photocurable resin composition containing a photocationically polymerizable silsesquioxane compound. The cationic photocurable resin composition of the present invention,
Since a cured product excellent in photocurability and excellent in balance between surface hardness and elasticity can be formed, it is suitable as a photocationically curable coating agent composition.

[0002]

2. Description of the Related Art In the field of ultraviolet (UV) -initiated polymerization or ultraviolet-initiated curing, photoinitiated radical polymerization using polyfunctional acrylates and unsaturated polyesters has been widely studied and industrially used.

However, there is a problem that this radical polymerization is inhibited by oxygen in the air or the like. Especially when the coating composition is cured by radical polymerization,
As the composition becomes thinner, the influence of polymerization inhibition by oxygen becomes more remarkable, and there is a limitation that the composition must be cured under an inert atmosphere in order to cure the composition quickly and completely.

[0004] On the other hand, the photoinitiated cationic polymerization is not affected by polymerization inhibition by oxygen unlike the photoinitiated radical polymerization, and can be completely polymerized even in the air. In particular, according to the composition using an epoxide or oxetane compound as a monomer, good heat resistance,
It is possible to obtain a cured product having excellent adhesive strength and good chemical resistance.

[0005]

However, a cured product formed from a photocationically curable composition using the above-mentioned epoxide or oxetane compound as a monomer has a basic skeletal structure of polyether. When used, there is a problem that the surface hardness tends to be insufficient.

An object of the present invention is to provide a cationic photocurable resin composition capable of adjusting properties such as surface hardness of a cured product.

[0007]

Means for Solving the Problems The present inventors added a silsesquioxane compound having an oxetanyl group to a conventional composition comprising a cationic photocurable monomer, thereby obtaining a cured product having a surface hardness. Was found to improve. Furthermore, since the silsesquioxane compound has good compatibility with other photocationic curable monomers, it has been found that the physical properties of the cured product can be adjusted by mixing these at an arbitrary ratio. The present invention has been completed.

That is, the cationic photocurable resin composition of the first invention according to the present invention is a photocationically polymerizable silsesquioxane obtained by hydrolyzing a compound represented by the following structural formula (I). It is characterized by containing a compound (a), a cationic photopolymerizable compound (b) other than the above (a), and a cationic photopolymerization initiator (c).

[0009]

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According to the first invention, the photocationic polymerizable silsesquioxane compound (a) (hereinafter referred to as “silsesquioxane compound (a)”) and the photocationic polymerizable compound (b) are used. The physical properties of the cured product formed from this composition can be arbitrarily adjusted by the mixing ratio. Therefore, this composition can be used in various fields by designing the balance of the surface hardness, elasticity, etc. of the cured product according to the use. For example, the composition of the present invention can be suitably used as a hard coating agent if it has a composition that forms a cured film whose surface hardness is improved within a range where practically sufficient elasticity can be maintained.

In the above formula (I), R ⁰ is preferably an organic functional group represented by the following structural formula (II), as in the second invention.

[0012]

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[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
In the present specification, a compound having an oxetanyl group is referred to as an “oxetane compound”.

(1) Silsesquioxane Compound (a) The silsesquioxane compound (a) in the photocationically curable resin composition of the present invention is represented by the above structural formula (I) as a raw material. And obtained by hydrolyzing this compound using a silicon compound. Here, the hydrolysis is preferably performed in an atmosphere having a pH of 7 or more. This is because the oxetanyl group is liable to open when hydrolyzed in an acidic atmosphere, which may cause the gelation of the system, and the oxetanyl group is consumed and the curability of the silsesquioxane compound (a) is reduced. It is because it falls. This hydrolysis is particularly preferably performed in an atmosphere having a pH of 9 to 13. When the pH is less than 9, the production efficiency of the silsesquioxane compound (a) decreases because the rate of hydrolysis and condensation of the silicon compound is low. On the other hand, when the pH exceeds 13, the amount of the alkali agent and the like used increases, so that it is not economical and the step of removing the alkali agent and the like from the reaction system becomes complicated.

R ⁰ in the above formula (I) is not particularly limited as long as it is an organic functional group having at least one oxetanyl group in a part thereof, and is a group represented by the structural formula shown in the above formula (II). Preferably, there is. In the formula (II), R ¹ is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and it is particularly preferable that R ¹ is an ethyl group. Also,
R ² is an alkylene group having 2 to 6 carbon atoms, and particularly preferably, R ² is a propylene group. This is because it is easy to obtain or synthesize such an oxetane compound. When the composition of the present invention is used as a photocationically curable coating agent composition, when the number of carbon atoms of R ¹ or R ² in the silsesquioxane compound (a) is 7 or more, the composition It is not preferable because the surface hardness of the formed film tends to be insufficient.

X in the above formula (I) is not particularly limited as long as it is a hydrolyzable group.
It is preferably a cycloalkoxy group or an aryloxy group. Further, one molecule of this compound contains three X's, and these may be all the same group or two or more different groups. As the other hydrolyzable group, a halogen atom can be mentioned. In this case, since the hydrogen halide is generated by the hydrolysis, the reaction system is likely to be in an acidic atmosphere, and thus the oxetanyl group may be opened.

The above "alkoxy group" includes, for example, methoxy group, ethoxy group, n- and i-propoxy group,
-, I- and t-butoxy groups. Also,
Examples of the “cycloalkoxy group” include a cyclohexyloxy group and the like, and examples of the “aryloxy group” include a phenyloxy group and the like. Among them, X is preferably an alkoxy group having 1 to 3 carbon atoms because the alkoxy group has good hydrolyzability. Further, the availability of raw materials is easy, and the silsesquioxane compound (a)
It is particularly preferable that X is an ethoxy group because the hydrolysis reaction during the production of is easily controlled.

When the compound represented by the formula (I) is hydrolyzed, the system is preferably set to an atmosphere having a pH of 7 or more.
Therefore, an alkali agent is usually added to the system. As the alkaline agent, ammonia, quaternary ammonium salts, organic amines and the like can be used, and quaternary ammonium salts are preferably used because they have good activity as basic catalysts. Other reaction conditions during the hydrolysis are not particularly limited, but the preferred reaction temperature is 10 to 1
20 ° C. (more preferably 20-80 ° C.), and a suitable reaction time is 2-30 hours (more preferably 4-24 hours). The organic solvent used in the hydrolysis is not particularly limited, and examples thereof include alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol; ketones such as acetone and methyl ethyl ketone; tetrahydrofuran, toluene, 1,4-dioxane, hexane, and the like.
Ligroin or the like can be used. Among them, those capable of uniformly dissolving the reaction system are preferable.

The silsesquioxane compound (a) in the composition of the present invention may be any of ladder, basket and random as long as it is produced by hydrolysis of the compound represented by the above formula (I). It may be composed of a silsesquioxane compound having a structure. This composition may contain only one kind of silsesquioxane compound, or may contain two or more kinds of silsesquioxane compounds having different structures or molecular weights.

The number average molecular weight of the silsesquioxane compound (a) is preferably from 600 to 5,000, more preferably from 1,000 to 3,000. When the number average molecular weight is less than 600, a film formed from the composition of the present invention may not have sufficient hardness. On the other hand, when the number average molecular weight exceeds 5,000, the viscosity of the silsesquioxane compound (a) becomes too high, which makes handling difficult, and the compatibility with other components may be reduced. In particular, when this composition is used as a coating composition, the number average molecular weight of the silsesquioxane compound (a) is from 1,000 to 1,000.
The ratio of the 3,000 silsesquioxane compound is preferably 50% by weight or more, more preferably 70% by weight or more. In addition, the number average molecular weight in the present specification is a molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC).

(2) Photocationically polymerizable compound (b) The photocationically polymerizable compound (b) in the photocationically curable resin composition of the present invention may be any compound other than the silsesquioxane compound (a). There is no particular limitation, and one or two or more compounds selected from compounds having a photocationically polymerizable group such as a vinyloxy group, an epoxy group or an oxetanyl group can be used. The number of cationic photopolymerizable groups in one molecule of the compound is not particularly limited, but it is preferable to use a bifunctional or higher functional cationic photopolymerizable compound (b) in order to improve curability.

Specific examples of the cationic photopolymerizable compound (b) include ethyl vinyl ether and the like having a vinyloxy group, bisphenol F diglycidyl ether and the like having an epoxy group, and 1,1 having an oxetanyl group. 4-bis [(3-ethyl-3-oxetanylmethoxy) methyl] benzene and the like can be mentioned.

Of these, it is preferable to use an epoxide or oxetane compound because a cured product having good heat resistance, excellent adhesive strength, and good chemical resistance can be formed as described above. In addition, it is particularly preferable to use an oxetane compound as the photocationically polymerizable compound (b), since the photopolymerization rate is generally higher than that of the epoxide and a higher degree of polymerization is easily obtained. In addition, the cationic photopolymerizable compound (b) is referred to as the “oxetane compound”
May include a compound represented by the above formula (I),
Further, it may contain an oxetane compound other than the silsesquioxane compound produced by hydrolysis of the compound represented by the above formula (I) or other side reaction.

(3) Cationic Photopolymerization Initiator (c) As the cationic photopolymerization initiator (c) in the photocationic curable resin composition of the present invention, generally used cationic photopolymerization is used. Any of the initiators can be used. For example, diallyliodonium salts and triarylsulfonium salts are preferably used.

(4) Mixing ratio of each component In the composition of the present invention, the proportion of the silsesquioxane compound (a) in the composition increases, and the surface hardness of the cured product tends to increase. . Further, since the silsesquioxane compound (a) is a silicon compound, an effect of imparting flame retardancy to the cured product, an effect of improving the heat resistance of the cured product, and the like can be expected. On the other hand, when the composition comprising only the silsesquioxane compound (a) is used, for example, as a coating agent, the cured film is excellent in surface hardness but low in elasticity, so that the mechanical strength of the film is insufficient. On the other hand, according to the composition of the present invention, the physical properties of the cured product can be balanced by adjusting the mixing ratio of the silsesquioxane compound (a) and the cationic photopolymerizable compound (b).

When the silsesquioxane compound (a) in the present invention is compared at the same molecular weight, for example, the silsesquioxane compound (a) is generally different from a compound obtained by introducing an oxetanyl group into silicone which is a one-dimensional polysiloxane. Excellent compatibility with cationic photopolymerizable compounds. For this reason, since the mixing ratio of the silsesquioxane compound (a) and the cationic photopolymerizable compound (b) can be selected from a wide range, there is an advantage that the physical properties of the cured product can be easily adjusted. In the composition of the present invention, the components (a) and (b) do not necessarily need to be completely compatible with each other, and can be put into practical use in consideration of the stability of the composition and the physical properties of the cured product. What is necessary is just to have compatibility.

The preferred mixing ratio of the component (a) and the component (b) varies depending on the composition of each component and the use of the composition of the present invention, but the component (a) / component (b) is in a weight ratio. It is preferably in the range of 5/95 to 95/5, and 1
More preferably, it is in the range of 0/90 to 90/10. If any component is less than 5% by weight based on the total weight of the component (a) and the component (b), the effect of adding the component may not be sufficiently exhibited.

The amount of the component (c) added is (a)
It is usually preferably in the range of 1 to 10% by weight, more preferably 3 to 5% by weight, based on the total weight of the component and the component (b).

The cationic photocurable resin composition of the present invention comprises
In addition to the components (a) to (c), general additives such as a viscosity modifier, a leveling agent, a stabilizer, and a silane coupling agent can be included. Further, the composition may contain an organic solvent, but the content thereof is 20% based on the whole composition.
It is preferably at most 10% by weight, more preferably at most 10% by weight.

[0030]

EXAMPLES The present invention will be described more specifically with reference to the following examples.

(1) Synthesis of Silsesquioxane Compound (a) (Synthesis Example 1) A silsesquioxane compound A was obtained by hydrolyzing a silicon compound represented by the following formula (III). Hereinafter, the silicon compound represented by the formula (III) is referred to as “Oxe-T
RIES ".

[0032]

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(1) In a reactor equipped with a stirrer and a thermometer,
30 ml of isopropyl alcohol and tetramethylammonium hydroxide (hereinafter also referred to as “Me ₄ NOH”)
0.91 g of 0% aqueous solution (H ₂ O; 45.6 mmol, M
e ₄ NOH; 1.0 mmol), 2.42 g of water (13
4.4 mmol), and then Oxe-TRIES1
9.23 g (60.0 mmol) were gradually added, and the mixture was stirred and left at room temperature for 24 hours. At this time, the pH of the reaction system was 1
1.5. (2) After the completion of the reaction, 100 ml of toluene was added to the system, and the reaction solution was washed with saturated saline using a separating funnel. (3) After repeatedly washing with water until the aqueous layer of the separating funnel becomes neutral, the organic layer is separated, dehydrated with anhydrous sodium sulfate, and toluene is distilled off under reduced pressure to obtain the desired silsesquie. Oxane compound A was obtained. The number average molecular weight of this silsesquioxane compound A was 1,800.

(Synthesis Example 2) A silsesquioxane compound B was obtained by hydrolyzing a silicon compound represented by the following formula (IV). Hereinafter, the silicon compound represented by the formula (IV) is referred to as “Epx-TRIES”.

[0035]

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(1) In a reactor equipped with a stirrer and a thermometer,
30 ml of isopropyl alcohol, 10 of Me ₄ NOH
% Aqueous solution 0.91 g (H ₂ O; 45.6 mmol, Me ₄
NOH; 1.0 mmol), 2.42 g of water (134.4).
mmol) and then Epx-TRIES 16.7.
0 g (60.0 mmol) was gradually added, and the mixture was stirred at room temperature for 24 hours. At this time, the pH of the reaction system was 11.5. (2) After completion of the reaction, the same treatment as in Synthesis Example 1 was performed to obtain a silsesquioxane compound B. The number average molecular weight of the obtained silsesquioxane compound B was 1,500.

(2) Preparation of Photocationic Curable Resin Composition The silsesquioxane compound A or B obtained in Synthesis Examples 1 and 2 in the ratio shown in Table 1 below, and the photocationism shown in (V) below 2.5% by weight based on the total weight of the polymerizable compound (b) and bis (dodecylphenyl) iodonium hexafluoroantimonate ((a) and (b) as the cationic photopolymerization initiator (c) ) Were mixed to prepare the photocationically curable resin compositions of Examples 1 to 5 and Comparative Examples 1 and 2. At this time, all the compositions of Examples 1 to 5 were transparent, indicating that the compatibility of each component was good.

[0038]

[Table 1]

[0039]

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(3) Evaluation of Photocationic Curable Resin Composition The curability, pencil hardness and elasticity of the photocationic curable resin compositions of Examples 1 to 5 and Comparative Examples 1 and 2 were evaluated by the following methods. . The results are shown in Table 2 below.

(1) Curability Each composition was coated on a glass substrate for about 2 hours using a bar coater.
It was applied to a thickness of 0 μm and irradiated with ultraviolet rays under the following conditions, and the number of times of irradiation until the tack on the surface disappeared was measured. [UV irradiation conditions] Lamp: 80 W / cm high-pressure mercury lamp Lamp height: 10 cm Conveyor speed: 10 m / min Irradiation atmosphere: in air

(2) Pencil hardness Each composition is applied to a thickness of about 20 μm on a steel plate and a glass substrate using a bar coater, and is irradiated with ultraviolet rays five times under the above irradiation conditions to obtain a cured film. Was. The pencil hardness of the surface of the cured film was measured according to JIS K5400.

(3) Elasticity The cured film obtained in the above (2) was subjected to a sensory evaluation on the ease of peeling and the feel when the cured film was to be peeled off from the substrate with a knife tip. The evaluation results were expressed in three stages: Δ; supple and difficult to peel off; Δ; slightly less pliable; ×; peeled off crisp.

[0044]

[Table 2]

As can be seen from Table 2, the cured film formed from the composition of the present invention was different from the cured film formed from the composition of Comparative Example 1 containing no silsesquioxane compound. As the mixing ratio of the silsesquioxane compound increased to 4, the hardness of both the flaw and the peel improved. Similarly, in Example 5, a cured film having higher hardness than the cured film formed from the composition of Comparative Example 1 was obtained. The cured films of Examples 1 to 5 all had moderate elasticity. On the other hand, the composition of Comparative Example 2 containing no photocationic polymerizable compound formed a film having higher hardness than that of Example 4, but this cured film lacked elasticity. It was easy to peel off from. In addition, the compositions of Examples 1 to 5 all showed good photocurability, but compared with Example 5 using the silsesquioxene compound B having an epoxy group, the silsesquioxane having an oxetanyl group was used. It can be seen that Example 3 using the sun compound A has higher photocurability.

The present invention is not limited to the specific embodiments described above, but may be variously modified within the scope of the present invention in accordance with the purpose and application.

[0047]

The cationic photocurable resin composition of the present invention contains a silsesquioxane compound (a) and a cationic photopolymerizable compound (b). Because the compatibility with the components is relatively high,
The physical properties of the cured product can be arbitrarily adjusted by the mixing ratio of these components. Accordingly, for example, a cured product having an excellent balance between surface hardness and elasticity can be formed, so that the composition of the present invention is useful as a coating composition or the like. Further, since the silsesquioxane compound (a) has an oxetanyl group having a high photocationic polymerization rate, the composition of the present invention has good photocurability.

Claims (2)

[Claims] 1. A photocationically polymerizable silsesquioxane compound (a) obtained by hydrolyzing a compound represented by the following structural formula (I), and a photocationically polymerizable compound other than the above (a) A cationic photocurable resin composition comprising: a compound (b); and a cationic photopolymerization initiator (c). Embedded image (2) R ⁰ in the above formula (I) is the following formula (I)
The cationic photocurable resin composition according to claim 1, which is an organic functional group represented by the structural formula shown in I). Embedded image