JPH07216232A - UV-curable organopolysiloxane composition - Google Patents

Abstract

(57) [Summary] [Structure] (A) A linear organopolysiloxane having at least one acryloxy group and / or methacryloxy group at each end of the molecular chain, (B) the following general formula (1): [R ¹ is the following general formula (2): (R ³ is a divalent hydrocarbon group. R ⁴ is —H or —CH _3. )
A group represented by or a methyl group. R ² is a group represented by the above general formula (2). m and n are m + n ≧ 10 and 0.05 ≦ m / (m + n) ≦
A positive integer that satisfies 0.5. ] The diorganopolysiloxane represented by the following, and (C) a UV-curable organopolysiloxane composition comprising a photopolymerization initiator, and a method for producing a cured product using the composition. [Effect] A silicone rubber elastic body having excellent mechanical strength can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid ultraviolet-curable organopolysiloxane composition which is cured by irradiation with ultraviolet rays to form an elastic body having high strength, and a method for producing a cured product using the composition.

[0002]

2. Description of the Related Art Ultraviolet ray curable organopolysiloxane compositions have recently been used in the electrical and electronic industries and various machines because cured products are excellent in heat resistance, cold resistance, releasability and electrical insulation. Used in industry.

Conventionally, as an ultraviolet-curable organopolysiloxane composition, for example, a composition comprising an alkenyl group-containing polysiloxane, a mercapto group-containing polysiloxane and a photopolymerization initiator, an acryloxy group or a methacryloxy group is used. A composition comprising a polysiloxane and a photopolymerization initiator contained therein, a composition comprising an organopolysiloxane containing an epoxy group and an onium salt, etc. are known. However, a conventional cured product of an ultraviolet-curable organopolysiloxane composition has a drawback of low mechanical strength, so that its application range is limited.

[0004]

Therefore, in order to improve the mechanical strength, a method of adding a reinforcing filler such as fumed silica to the above composition has been attempted. However, when the reinforcing filler is added to the composition, it causes an increase in the viscosity of the composition and a reversion of plasticization, and there are new problems such as lack of transparency and insufficient curing of the obtained cured product. occured.

Therefore, an object of the present invention is to provide an ultraviolet-curable organopolysiloxane composition which gives an elastic body having improved mechanical strength without the above problems, and a method for producing a cured product using the composition. To provide.

[0006]

Means for Solving the Problems The inventors of the present invention have made extensive studies on improving the mechanical strength of a cured product of a composition comprising a polysiloxane containing an acryloxy group or a methacryloxy group and a photopolymerization initiator. As a result, an acryloxy group and / or a methacryloxy group (hereinafter,
It may be referred to as a (meth) acryloxy group. ) Containing a linear organopolysiloxane and an organopolysiloxane containing a (meth) acryloxy group in the side chain, a composition capable of obtaining a cured product having excellent mechanical strength can be obtained. The present invention has been completed and the present invention has been completed.

The present invention comprises (A) at least one group selected from the group consisting of an acryloxy group and a methacryloxy group at each end of a molecular chain and having a viscosity at 25 ° C. of 1000.
A linear organopolysiloxane of 00 cP or less, (B) the following general formula (1):

[0008]

[Chemical 3] [In the formula, a plurality of R ¹ may be the same or different and each is represented by the following general formula (2):

[0009]

[Chemical 4]

(In the formula, R ³ is a divalent hydrocarbon group,
R ⁴ is -H or -CH _3. ) Or a methyl group, R ² is a group represented by the above general formula (2), and when plural R ² are present, they may be the same or different, and m and n is m + n ≧ 10 and 0.05 ≦ m /
It is a positive integer that satisfies (m + n) ≦ 0.5. ], A diorganopolysiloxane having a viscosity of 100000 cP or less,
And (C) a UV-curable organopolysiloxane composition containing a photopolymerization initiator.

The present invention also provides a method for producing a cured product, which comprises curing the above ultraviolet-curable organopolysiloxane composition by irradiation with ultraviolet light.

Component (A) The linear organopolysiloxane of component (A) contains at least one group selected from the group consisting of an acryloxy group and a methacryloxy group at each end of the molecular chain, and the side chain thereof contains It is a compound containing no group. The (meth) acryloxy group is, for example, an alkylene group such as a methylene group, an ethylene group or a propylene group, or, for example,

[0013]

[Chemical 5] Is bonded to the silicon atom via a divalent linking group such as

The linear organopolysiloxane as the component (A) may be, for example, an alkyl group such as a methyl group, an ethyl group, a propyl group or a butyl group in addition to the above-mentioned group containing a (meth) acryloxy group; Aryl groups such as phenyl groups and tolyl groups; for example, cycloalkyl groups such as cyclohexyl groups; some or all of the hydrogen atoms bonded to carbon atoms of these groups are substituted with substituents such as halogen atoms and cyano groups. It has a monovalent organic group such as a chloromethyl group, a trifluoropropyl group, and a cyanomethyl group. These groups may be used alone or in combination of two or more.
Considering the compatibility with the component (B) described later, it is preferable that the phenyl group is contained in an amount of 3 to 10 mol% in all the organic groups of the linear organopolysiloxane of the component (A).

Specific examples of the linear organopolysiloxane as the component (A) include the following compounds.

[0016]

[Chemical 6]

(In each formula, a plurality of R ^{5 s} may be the same or different and are an acryloxy group or a methacryloxy group,
i is a positive integer and j is a positive integer. )

Further, the linear organopolysiloxane as the component (A) is required to be a liquid having a relatively low degree of polymerization in order to maintain fluidity at room temperature and to obtain good curability. Specifically, it is necessary that the viscosity at 25 ° C. is 100,000 cP or less, and particularly preferably in the range of 1,000 to 10,000 cP. If the degree of polymerization is too low, the resulting cured product becomes brittle,
The degree of polymerization is
It is preferably 100 or more.

Component (B) The organopolysiloxane of component (B) has the general formula (1)
Is a compound having a plurality of (meth) acryloxy group-containing groups in its side chain. The component (B) imparts mechanical strength to the elastic body obtained by curing the composition of the present invention.

In the general formula (1), a plurality of R ^{1 s} may be the same or different and are a group represented by the general formula (2) or a methyl group. R ² is a group represented by the above general formula (2), and when plural R ² are present, they may be the same or different.

R ³ in the above general formula (2) is a divalent hydrocarbon group connecting an acryloxy group or a methacryloxy group and a silicon atom, and specifically, for example, a methylene group,
Examples thereof include alkylene groups such as ethylene group and propylene group. R ⁴ in the general formula (2) is an acryloxy group or a methacryloxy group.

In the general formula (1), m and n are m + n ≧
10 and a positive integer satisfying 0.05 ≦ m / (m + n) ≦ 0.5. That is, the diorganopolysiloxane of the component (B) is
It contains 5 to 50 mol% of diorganosiloxane units having a (meth) acryloxy group-containing group and a methyl group in one molecule. If the unit is less than 5 mol%,
The strength of the cured product obtained by curing the composition of the present invention decreases, and when it exceeds 50 mol%, the compatibility with the above-mentioned component (A) deteriorates.

Specific examples of the organopolysiloxane as the component (B) include the following compounds.

[0024]

[Chemical 7] (In each formula, plural R ^{5 s} may be the same or different and are as described above, and m and n are also as described above.)

The component (B), the diorganopolysiloxane, must have a viscosity of 100,000 cP or less at 25 ° C. in order to maintain fluidity at room temperature, and particularly, 1,000-10,000 cP.
The P range is preferred.

The blending amount of the component (B) is preferably in the range of 5 to 200 parts by weight, and more preferably 10 to 10 parts by weight, per 100 parts by weight of the component (A).
A range of 0 parts by weight is preferred.

Component (C) The photopolymerization initiator of component (C) is a catalyst for promoting cross-linking polymerization of the acryloxy group or methacryloxy group of the components (A) and (B) by ultraviolet irradiation.

As the photopolymerization initiator as the component (C), those which cleave themselves to generate radicals and those which are used in combination by combining an aromatic ketone and a hydrogen donor are used. Examples of the former include, for example, benzoin isobutyl ether, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 2-benzyl-2-dimethylamino-1- (4 -Morpholinophenyl) -butanone and the like can be mentioned. As the aromatic ketone of the latter example,
Examples thereof include benzophenone, 4-phenylbenzophenone, 2-isopropylthioxanthone, and the like, and hydrogen donors combined therewith include, for example, methyldiethanolamine, triethanolamine, p-dimethylaminoacetophenone, ethyl p-dimethylaminobenzoate, Examples include amine compounds such as 4,4′-bis (diethylaminobenzophenone).

The photopolymerization initiator as the component (C) may be used alone or in combination of two or more. Further, the blending amount of the component (C) is the same as that of the component (A) and
The range of 0.1 to 10% by weight is preferable, and the range of 1 to 5% by weight is more preferable, based on the total weight of the component (B).

Other Additives In addition to the components (A) to (C) described above, the composition of the present invention may be, for example, a thermal polymerization inhibitor, an antioxidant, an ultraviolet ray, etc., as long as the effects of the present invention are not impaired. Additives known per se such as an absorbent, a flow control agent, and an adhesion promoter can be appropriately blended.

Organopolysiloxane Composition The composition of the present invention can be obtained as a one-pack type ultraviolet curable composition by uniformly mixing the above-mentioned components.
This composition is a fluid liquid and is shaped into an appropriate shape and then cured by irradiation with ultraviolet rays to give a silicone rubber elastic body. Since this elastic body has excellent mechanical strength, it can be used as a potting material, a coating material, an adhesive, a sealing material, and an electrical insulating material for electric / electronic parts.
It is expected to be effectively used for various applications such as coating materials for metals, glass, ceramics, release agents for plastics, papers, etc., coating materials for glass fibers for optical communication.

[0032]

EXAMPLES Examples 1 to 4 and Comparative Examples 1 to 5 As the component (A), an organopolysiloxane represented by the following formula (a) or (b) was used.

[Chemical 8]

As the component (B), the following formulas (c), (d) or
The organopolysiloxane represented by (e) was used.

[Chemical 9]

As the component (C), a photopolymerization initiator represented by the following formula (f) was used.

[Chemical 10]

In each of the Examples and Comparative Examples, the components (A) to (C) shown in Table 1 were mixed at the compounding ratio shown in Table 1 to prepare a composition. By curing each composition by the following method,
The strength, elongation and hardness of the obtained cured product were measured according to JIS C 2123. The results are shown in Table 1.

To cure the cured composition, a belt conveyor type ultraviolet irradiation device was used in which two 80 W / cm high-pressure mercury lamps were installed 10 cm above the belt line. The above composition was poured into a mold having a depth of 200 μm, the obtained molded product was placed on the belt line, and the speed of the belt line was set to 10 m / min to irradiate ultraviolet rays to cure the composition.

[0037]

[Table 1]

[0038]

The ultraviolet-curable organopolysiloxane composition of the present invention provides a silicone rubber elastic body having high mechanical strength. Therefore, potting materials, coating materials, adhesives, sealing materials, coating materials for metals, glass, ceramics, etc., release agents for plastics, paper, etc., coatings for optical communication glass fibers as electrical insulating materials for electric / electronic parts. It is expected to be effectively used for various purposes such as wood.

Claims (2)

[Claims] (A) A linear organopolysiloxane having at least one group selected from the group consisting of an acryloxy group and a methacryloxy group at each end of a molecular chain and having a viscosity at 25 ° C of 100000 cP or less, (B) ) The following general formula (1): [In the formula, plural R ^{1 s} may be the same or different and each is represented by the following general formula (2): (In the formula, R ³ is a divalent hydrocarbon group, R ⁴ is —H or —CH ₃ ), or a methyl group,
R ² is a group represented by the above general formula (2), and when plural R ² are present, they may be the same or different,
m and n are m + n ≧ 10 and 0.05 ≦ m / (m + n) ≦ 0.
It is a positive integer that satisfies 5. ], The viscosity is 1000
An ultraviolet-curable organopolysiloxane composition comprising a diorganopolysiloxane of 00 cP or less and (C) a photopolymerization initiator. 2. A method for producing a cured product, which comprises curing the composition according to claim 1 by irradiation of ultraviolet rays.