JPS63117024A - Ultraviolet-curable silicone composition - Google Patents

Abstract

PURPOSE:To obtain the title composition which is excellent in low-temperature properties and can be satisfactorily cured by UV radiation even in the presence of oxygen, by mixing a specified polysiloxane with a specified acrylic compound and a sensitizer. CONSTITUTION:A (meth)acryloxy group-containing trifunctional silane, an aryl group-containing chlorosilane and a bifunctional silane are hydrolyzed together and condensed in the presence of a catalyst such as KOH to give a polysiloxane (A) of formula I [wherein R<1> is H or methyl, Q<1> is an (un)substituted bivalent 1-5C hydrocarbon group, R<2> is an (un)substituted aryl, R<3> is an (un)substituted monovalent hydrocarbon group, a is 1-3, b is 0-8, c is 0-3, d is 2-10, a/(a+b+c+d)>=0.08 and (b+c)/(a+b+c+d)>=0.10]. 100pts.wt. in total of 100pts.wt. component A and 5-2,000pts.wt. acrylic compound (B) of formula II (wherein R<4> is R<1>, R<5> is a 1-3C alkyl or aryl, Q<2> is a 1-5C bivalent hydrocarbon group, and e is 0-8) is mixed with 0.5-15pts.wt. sensitizer (C) (e.g., 2-hydroxy-2- methyl-1-phenylpropan-1-one).

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an ultraviolet curable silicone composition, and more particularly to an ultraviolet curable silicone composition that exhibits good curability even in the presence of oxygen.

[Technical background of the invention and its problems]

Compositions and methods for curing silicone with ultraviolet light include
Described in the prior art. For example, U.S. Pat.
No. 26,710 discloses a curing method in which various sensitizers are added to vinyl group-containing polyorganosiloxane and high-intensity ultraviolet irradiation is used. However, this method has the disadvantage that curing occurs only on the surface and does not uniformly cure the inside. Also, U.S. Patent No. 3.816.
No. 282 proposes a composition in which addition crosslinking is performed using a mercapto group-containing polyorganosiloxane, polymethylvinylsiloxane, and various organic peroxides, but this composition has poor storage stability at room temperature and does not gel. There was a serious drawback in that it progressed. In addition, the synthesis of mercapto group-containing polyorganosiloxanes requires a multi-step process, and there are also drawbacks such as emitting a bad odor peculiar to mercapto groups. Furthermore, JP-A-50-86553 discloses a composition comprising a mercapto group-containing polyorganosiloxane and a dihydric phenol or its alkyl derivative as a gelling inhibitor, but the stability during storage is improved. However, the drawbacks mentioned above for mercapto group-containing polyorganosiloxanes remained as well. Furthermore, there was a drawback that the curing was limited to only the surface and the inside was not uniformly cured. Furthermore, JP-A No. 50-61486 discloses a composition that is crosslinked by an addition reaction using a vinyl group-containing polyorganosiloxane, a polyorganohydrodiene siloxane, and an exacerbating agent, but this also cures only the surface. It has the serious disadvantage that it does not harden to the inside and causes foaming. Furthermore, JP-A-48-19682 proposes a composition consisting of an acrylic unsaturated group-containing polyorganosiloxane and an aggravating agent, but while this method has an excellent photosensitizing effect, it is susceptible to the effects of oxygen. It has the drawbacks of being easily susceptible to photosensitivity, and having large changes in photosensitivity over time and dark decay. Moreover, the synthesis of the polyorganosiloxane containing an acrylic unsaturated group requires multiple steps, and the resulting silicone has the disadvantage of poor heat resistance. Further, a composition comprising an azide group-containing polyorganosiloxane, a vinyl i-containing polyorganosiloxane, and an organic peroxide has been proposed in JP-A-54-69197. This is a hydrogen abstraction reaction from the hydrocarbon group of the polyorganosiloxane by decomposition of the azide in the azide group-containing polyorganosiloxane, an insertion reaction into the vinyl group of the vinyl group-containing polyorganosiloxane, and crosslinking by a coupling reaction between nitrenes. Further, hydrogen abstraction reaction from the hydrocarbon groups of polyorganosiloxane by decomposition of organic peroxide and crosslinking reaction by insertion reaction into vinyl groups of polyorganosiloxane containing vinyl groups are used simultaneously. This proposal had the advantage of having excellent photosensitivity, being unaffected by oxygen, and having little change in photosensitivity over time, but had the disadvantage of yellowing. Furthermore, JP-A-55-125123 discloses a method of irradiating a vinyl group-containing polyorganosiloxane or a composition comprising a vinyl group-containing polyorganosiloxane and an organic peroxide with ultraviolet rays with a wavelength of 100 to 300 nm. However, in the case of only vinyl group-containing polyorganosiloxane, the disadvantage is that only the surface is cured, and the deep part is not cured, and the curing time is too long to be practical. there were. In addition, when using organic peroxides in combination, the beryoxykecool-based, dialkyl-based, and ester-based organic peroxides exemplified in the same patent do not have an uncured surface and the curing time is too long for practical use. The drawback was that it required a long time.

Furthermore, JP-A-48-16991 and JP-A-53
JP-134085 discloses a composition comprising a methacryloylpropoxy-modified polysiloxane, a sensitizer, and a solvent, and describes that a film with high strength is formed by ultraviolet irradiation. Furthermore, JP-A-54-162787 discloses a composition comprising a (meth)acryloxyalkyl group-containing polyorganosiloxane, an acrylate crosslinking agent, and a photosensitizer, which can be rapidly cured by low-energy ultraviolet irradiation. It is written. However, all of these acrylic group-containing compositions have the problem that they are insufficiently cured when irradiated with ultraviolet rays in the presence of oxygen, leaving a sticky state on the surface.

[Purpose of the invention]

An object of the present invention is to provide a silicone composition that is well cured by ultraviolet irradiation even in the presence of oxygen and has excellent low-temperature properties.

[Structure of the invention]

As a result of repeated studies to obtain such an ultraviolet curable silicone composition, the present inventors have developed a three-dimensional structure containing a siloxane unit having a three-dimensional structure containing a (meth)acryloki dialkyl group and an allyl group. The present inventors have discovered that by using a silicone compound having a siloxane unit, it is possible to obtain a composition that is well cured by ultraviolet irradiation even in the presence of oxygen, and has thus arrived at the present invention.

The present invention is characterized in that: (A) average formula; aryl group, R3 is a substituted or unsubstituted monovalent hydrocarbon group, a is 1 to 3, b is O to 8, C is O to 3, d is an integer of 2 to 1O, a/(a +
b + c + d)≧0.08 and (b+c)/(
a+b+c+d)≧0.10. ) 100 parts by weight of polysiloxane (B) Formula; % Formula % (In the formula, R4 is a hydrogen atom or a methyl group, R5 is an alkyl group or an aryl group having 1 to 3 carbon atoms, and Q2 is a carbon number 1
-5 divalent hydrocarbon group, e represents an integer of 0-8.

) Acrylic compound represented by 5-2
000 parts by weight (C) This is an ultraviolet curable silicone composition characterized by comprising 0.5 to 15 parts by weight of the sensitizer (A) + (B), based on a total of 100 parts by weight.

The polysiloxane as the component (A) in the present invention is a compound represented by the average formula: It is a main component of the cured product in the composition of the present invention, and can be cured well by ultraviolet irradiation even in the presence of oxygen. This is the most characteristic component of the present invention. Examples of R1 include a hydrogen atom or a methyl group.

Ql is a substituted or unsubstituted divalent hydrocarbon group having 1 to 5 carbon atoms; alkylene groups such as methylene, ethylene, propylene, and butylene; arylene groups such as phenylene; and halogens in these groups. Examples include groups with substituted atoms, but for ease of synthesis, groups with 2 to 4 carbon atoms are preferred.
An alkylene group is preferred. Examples of R2 include aryl groups such as phenyl, tolyl, xylyl, and biphenyl, and substituted aryl groups such as 2,4-chlorophenyl. or 2,4-chlorophenyl group R3 is an alkyl group such as methyl group, ethyl group, propyl group, butyl group, isobutyl group, amyl group, hexyl group, octyl group, decyl group; allyl group , alkenyl groups such as cyclohexenyl; cycloalkyl groups such as cyclopentyl and cyclohexyl; alkaryl groups such as tolyl, xylyl and mesityl; aralkyl groups such as benzyl and phenylethyl; or A group in which some or all of the hydrogen atoms are substituted with a halogen atom, such as 3
．． 3.3-) Lifluoropropyl group, chloromethyl group, chlorophenyl group, cyanoethyl group, etc. are exemplified, but all are methyl groups from the viewpoint of ease of synthesis, strength and heat resistance of the formed cured film. It is preferable.

In addition, a, b, c, and d indicating each siloxane component are
a is an integer of 1 to 3, b is an integer of fJ<o to g, C is an integer of O to 3, and d is an integer of 2 to 10. In order to obtain good curability in air, a/ (a+b+c+d)≧
0.08 and (b+c)/(a+b+c+d)≧0.1
It is necessary to satisfy the condition of 0, and furthermore, b/(a
It is more preferable that +b+c+d)≧0.12.

Examples of such compounds include substances represented by the following average formula.

Such polysiloxanes include trifunctional silanes containing (meth)acryloxy groups such as r-(meth)acryloxypropyltrimethoxysilane; chlorosilanes containing aryl groups such as phenyltrichlorosilane, chlorophenyltrichlorosilane, and diphenyldichlorosilane. ; It is obtained by cohydrolyzing a difunctional silane such as dimethylchlorosilane by a well-known method and condensing it in the presence of a catalyst such as potassium hydroxide.

The acrylic compound (B) in the present invention is represented by R' 0 (in the formula, R', R', Q", and e are as described above), and when the component (A) is solid, acts as a solvent and is a component for maintaining the mechanical properties of the cured product. Examples of H4 include a hydrogen atom or a methyl group, similar to R'.

Examples of R5 include alkyl groups such as -methyl group, ethyl group, and propyl group; aryl groups such as phenyl group; however, when good photocurability is obtained and a high refractive index is required, aryl groups are used. is preferred. Q2 has 1 or more carbon atoms such as methylene group, ethylene group, propylene group, butylene group, etc.
Alkylene group in 5; Examples include aryl groups such as phenylene groups, and groups with substituents such as halogen on these groups, but alkylene groups with 2 to 4 carbon atoms are preferred due to compatibility with the (^) component. A group is preferable, and an ethylene group is more preferable from the viewpoint of toxicity and curability at low temperatures. Also, e is O~
It is an integer of 8, and is preferably an integer of 1 to 5 because it provides compatibility with component (A) and good curability.

The blending amount of component (B) in the present invention is 10% of component (A).
5 to 2000 parts by weight, preferably 10 to 0 parts by weight
It is 1000 parts by weight. If it is less than 5 parts by weight, the viscosity of the composition will be too high, causing problems in workability, and if it exceeds 2,000 parts by weight, the curability by ultraviolet irradiation in the presence of oxygen, which is a feature of the present invention, will be significantly impaired.

The sensitizer (C) in the present invention is excited upon receiving light, imparts excitation energy to the siloxane containing a (meth)acryloxy group, and promotes the curing reaction by ultraviolet irradiation. Such substances include acetophenone, benzoinpropyl ether, benzoin butyl ether, jetoxyacetophenone, 2-methyl-2-
Hydroxypropiophenone, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropanone,
2-Hydroxy-2-methyl-1-phenylpropane-
Examples include ketone or ether compounds such as 1-one, quinone compounds such as benzoquinone, anthraquinone, and 1,2-naphthoquinone, but 2-hydroxy-2-methyl-1-phenyl is used to speed up the curing speed. Most preferred is propan-1-one.

The blending amount of this component (C) is the total of (A) + (B) 1
0.5 to 15 parts by weight, preferably 1
．． It is 0 to 10 parts by weight. If it is less than 0.5 parts by weight, a desirable sensitizing effect cannot be obtained, and if it exceeds 15 parts by weight, the viscosity tends to increase and the stability of the system is impaired.

In the composition of the present invention, polyacrylic resin or polymethacrylic resin may be used as a thickener, if necessary.

Thereby, flexibility can also be imparted to the cured product.

However, if the amount is too large, the curability in the presence of oxygen due to ultraviolet rays will be lost, so the blending amount must be 10 parts by weight or less per 100 parts by weight of component (A). Further, as a softening agent, polymethylphenylsiloxane in which 5 to 40 mol % of the total organic compounds bonded to silicon are phenyl groups may be used, and thereby the hardness of the cured product can be adjusted. If this amount is too large, a separation phenomenon or bleeding from the cured product may occur, so the blending amount must be 10 parts by weight or less per 100 parts by weight of component (A).

In addition, in order to further improve the mechanical strength of the cured product,
Fumed silica, precipitated silica, pyrogenic silica,
There is no harm in adding silica airgel, quartz fine powder, etc. These silicas can be used alone or in combination of two or more, and even if used as is, the surface can be coated with polydimethylsiloxane, octa It may be used after being treated with an organosilicon compound such as methylcyclotetrasiloxane or hexamethyldisilazane.

Furthermore, a solvent can be used in the composition of the present invention for the purpose of adjusting the viscosity for coating on a support. Examples of such a solvent include ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, and aromatic hydrocarbon solvents such as benzene, toluene and xylene.

In addition to the above-mentioned solvents, in the composition of the present invention, for example, halogenated hydrocarbon solvents, alcohol solvents, ester solvents, etc. that are inert to (meth)acryloxy groups may be used as diluents. .

〔Effect of the invention〕

According to the composition of the present invention, unlike conventional ultraviolet curable silicone compositions, it can be effectively cured by short-time irradiation with ultraviolet light even in the presence of oxygen. The cured product thus obtained has extremely excellent electrical properties, heat resistance, and weather resistance. Therefore, the cured product can be applied to a wide range of applications, including protective coatings for semiconductor junctions, moisture-proof coatings for passive devices such as condenser coils, and primary and buffer coatings for optical fibers.

〔Example〕

Hereinafter, the present invention will be explained by examples. In the examples, all parts represent parts by weight.

Reference Example 1 1,000 parts of water and 1,000 parts of toluene were placed in a flask, the temperature was kept at 10°C, and γ-methacryloxypropyltriethoxysilane, phenyltrichlorosilane and dimethyldichlorosilane were added in the proportions shown in Table 1 for 1 hour. The solution was added dropwise over the course of 1 hour, and the mixture was kept at 70° C. for 1 hour to perform hydrolysis while stirring. After the reaction is complete, separate the lower layer, wash with water,
After dehydration by heating, the mixture was kept at 115°C for 5 hours in a 0.1 potassium hydroxide aqueous solution to carry out a condensation reaction, and then neutralized with ethylene chlorohydrin, toluene was partially removed, and filtered. A methacryloxy group-containing siloxane shown in Table 1 was obtained.

Table 1 here, C) 1.0 D: (C113)ZSiO It is.

Reference Example 2 The following compound was obtained as a methacryloxy group-containing siloxane as a comparative example compound.

In a flask, 1000 parts of water, 150 parts of toluene and n-
Charge 200 parts of butyl alcohol, and while maintaining the temperature at 10°C, add 150 parts of dimethyldichlorosilane, 100 parts of diphenyldichlorosilane, 40 parts of phenyltrichlorosilane, and 60 parts of γ-methacryloxypropyltriethoxysilane over 1 hour. Dripping, Reference Example 1
Hydrolyzed in the same manner. This was stirred for 30 minutes to separate the stationary condensate layer, and after washing with water, toluene was extracted by vacuum distillation.
Solid composition P is obtained by distilling off butyl alcohol, etc.
I got it.

Example 1 Acrylic compound C) 1 was added to the compounds (A1゜A2 and P) obtained in Reference Examples 1 and 2 in the proportions shown in Table 2.
．． =Cl1-Cken0CJah-0-Calls (Bl
) and 0H C2-methyl-1-phenylpropan-1-one) and uniformly dispersed with a universal kneader to form the composition of the present invention @
IJ511 to S14 and comparative compositions C11 and C12 were obtained.

These compositions were poured into a stainless steel container coated with polytetrafluoroethylene with a diameter of about 6 cm to a thickness of about 2 cm, and after defoaming, an
0W/cm high-pressure mercury lamp (manufactured by Ushio Inc., UV-
7000) in the air from a distance of 10 cm for 0.5 seconds, and the photocurability was examined by comparing and confirming the curing state. Further, for completely cured S11 to S14, the hardness of the cured products was measured by a method according to JIS K 6301. The results are shown in Table 2.

[Example 2 A2, 81 of Reference Example 1. Dial BR1 as a thickener
02 (manufactured by Mitsubishi Rayon i, poly (meth)acrylic resin), both ends are blocked with trimethylsiloxane units and the remainder consists of 70% dimethylsiloxane units and 30% diphenylsiloxane units, and the viscosity at 25°C is 200c.
St polymethylphenylsiloxane and 2-hydroxy-2-methyl-1-phenylpropan-1-one were uniformly mixed in the same manner as in Example 1 in the ratios shown in Table 3 to form composition 521. Obtained S22.

Regarding this composition, a photocurability test, hardness and viscosity were measured in the same manner as in Example 1.

All exhibited good photocurability. It is also understood that the hardness of the cured product can be lowered by using a thickener and polymethylphenylsiloxane.

Table 3 Reference Example 3 A flask was charged with 1,000 parts of water and 1,000 parts of toluene, and γ-methacryloxypropyltriethoxysilane, phenyltrichlorosilane, diphenyldichlorosilane and dimethyldichlorosilane were added in the same manner as in Example 1. They were blended in the proportions shown in the table and subjected to hydrolysis, condensation reaction, neutralization, desolvation, and filtration to obtain methacryloxy-containing siloxanes A3 to A6 shown in Table 4.

Example 3 To the compound 3~^6 and P, C) Iz=CH-CO
-(OCJ4)z-OC6H4・C91119(B2)
and 2-hydroxy-2-methyl-1-phenylpropan-1-one were mixed uniformly in the ratio shown in Table 5, and compositions S31 to S34 and comparative composition C31 were prepared.
I got it.

A photocuring test was conducted on these in the same manner as in Example 1 except that the irradiation conditions were changed to 0.5 seconds, 1 second, and 2 seconds. The results are shown in Table 5.

Claims (1)

[Claims] 1 (A) Average formula; ▲ Numerical formulas, chemical formulas, tables, etc. Substituted divalent hydrocarbon group, R^2 is a substituted or unsubstituted aryl group, R^3 is a substituted or unsubstituted monovalent hydrocarbon group, a is 1-3, b is 0-8, c represents an integer from 0 to 3, d represents an integer from 2 to 10, and a/(a+b
+c+d)≧0.08 and (b+c)/(a+b+c+
d) ≧0.10. ) 100 parts by weight of polysiloxane (B) Formula; ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ (In the formula, R^4 is a hydrogen atom or a methyl group, and R^5 is an alkyl group having 1 to 3 carbon atoms. or an aryl group, Q^2 is a divalent hydrocarbon group having 1 to 5 carbon atoms, and e represents an integer of 0 to 8.) 5 to 2000 parts by weight of an acrylic compound (C) Sensitizer ( 0.5 to 1 per 100 parts by weight of A) + (B)
5 parts by weight of an ultraviolet curable silicone composition. 2. The composition according to claim 1, wherein Q^1 in (A) is an alkylene group having 2 to 4 carbon atoms. 3. The composition according to claim 1, wherein R^2 in (A) is a phenyl group or a 2,4-chlorophenyl group. 4. The composition according to claim 1, wherein R^3 in (A) is a methyl group. 5. The composition according to claim 1, wherein b/(a+b+c+d) of (A) is 0.12 or more. 6. The composition according to claim 1, wherein R^5 in (B) is an aryl group. 7. The composition according to claim 1, wherein Q^2 in (B) is an ethylene group. 8. The composition according to claim 1, wherein e in (B) is an integer of 1 to 5. 9. The composition according to claim 1, wherein the amount of component (B) is 10 to 1000 parts by weight per 100 parts by weight of component (A). 10. The composition of claim 1, wherein (C) is 2-hydroxy-2-methyl-1-phenylpropan-1-one. 11 The blending amount of component (C) is (A) + (B), total 10
The composition according to claim 1, wherein the amount is 1.0 to 10 parts by weight relative to 0 parts by weight.