JPH06279679A - Curable organopolysiloxane composition and cured product thereof - Google Patents

Abstract

PURPOSE:To provide the subject composition containing a specific hydroxy- terminated organopolysiloxane, etc., curable in a short time, having excellent adhesion, storage stability and corrosion resistance and useful for sealing agent, etc. CONSTITUTION:The objective composition contains (A) a hydroxy-terminated organopolysiloxane of formula I [R<1> is (substituted) univalent hydrocarbon group; (n) is 1-10,000], (B) a (meth)acryl-functional alkoxysilane of formula II (R<2> is H or methyl; R<3> is bivalent organic group; R<4> and R<5> are R<1>; (a) is 0-2), (C) a bivalent tin compound of the formula SnX2 (X is halogen, alkoxy or carboxyl), (D) an alkoxy-alpha-silyl ester of formula III [R<8> and R<9> are methyl or ethyl; R<10> and R<11> are H or (substituted) univalent hydrocarbon group; R<12> is (substituted) univalent hydrocarbon group; (b) is 0-2], (E) a silacyclo-cyclic compound having alkenoxy group, (F) an onium salt compound, (G) a photo-polymerization initiator and (H) a curing catalyst. A cured product can be produced by curing the composition.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a curable organopolysiloxane composition which can be cured by either room temperature curing or photo-curing.

[0002]

2. Description of the Related Art Various room temperature curable organopolysiloxane compositions (hereinafter abbreviated as RTV siloxane compositions) are known. Among them, a composition obtained by adding a cross-linking agent such as methyltrimethoxysilane and a catalyst such as an organic titanium compound or a titanium chelate compound to an organopolysiloxane having a hydroxyl group at the terminal of the molecular chain, generates alcohol during curing to give a rubber-like composition. To form the organopolysiloxane of. Therefore,
This curable composition is not corrosive and does not generate an irritating odor, and is therefore widely used as an adhesive in the electrical or electronic industry.

However, this type of dealcohol type RTV
Siloxane compositions generally have the drawbacks of slow curing speed, poor internal curability and poor storage stability, and in the case of long-term storage, there is the problem that even if they are anhydrous, they will not cure during use.

Therefore, this type of dealcoholized RT
A method has been proposed in which a silane compound having two alkoxy groups is added to a V siloxane composition as a so-called silas scavenger to improve its storage stability and curability. Further, as the dealcohol-type RTV siloxane composition, a diorganopolysiloxane having a molecular chain end blocked with a hydroxyl group, an alkoxysilane or a partial hydrolyzate thereof, represented by the following formula: [(CH ₃ ) ₂ N] C = N ( CH _{2) 3} -Si (OCH
₃ ) A product obtained by adding a guanidyl-substituted alkylalkoxysilane represented by ₃ and an organic tin compound has been proposed (see Japanese Patent Application Laid-Open No. 58-52351).

However, in a composition in which a silane compound having two alkoxy groups is blended as a silas scavenger, in order to improve the storage stability, a group other than the two alkoxy groups of the silane compound is used as an amide. It is necessary to have a highly reactive hydrolyzable group such as a group or an amino group. Therefore, this composition has a problem of causing corrosiveness and odor, which limits its use as an adhesive in the electrical and electronic industries. In addition, the present inventors have previously proposed a dealcohol type RTV siloxane composition in which an α-silyl ester compound having a highly active reactivity to alcohols is blended to solve this disadvantage (Japanese Patent Application Laid-Open No. Hei 10 (1999) -242242). 3-47868 gazette). This composition has good storage stability and effectively avoids corrosiveness and odor.

However, due to the speeding up of production lines in the electric and electronic industries in recent years, it has been required to improve the curing speed of curable compositions used for adhesives and the like. RTV such as
Siloxane compositions have not met the requirements regarding their cure rate.

In contrast to the conventionally known curable compositions such as condensation type, heat curable type, platinum addition reaction type and the like, UV curable compositions are known as those having a curing mechanism with a fast curing speed.

[0008]

As a UV-curable organopolysiloxane composition, for example, one obtained by curing a vinyl group-containing polysiloxane and a mercapto group-containing polysiloxane by a photoradical addition reaction is known. (Japanese Patent Publication No. 52-40334 and Japanese Patent Laid-Open No. 60)
-104158). However, this composition has problems in odor due to mercapto group and in corrosiveness to metal, so that its use is limited.

Further, as a composition which is cured by irradiation with light, a composition comprising an acrylic group-containing polysiloxane and a sensitizer has been proposed (Japanese Patent Publication No. 53-36515 and Japanese Patent Laid-Open No. 60-215009). reference). However, in this composition, it is necessary to use a high molecular weight linear polymer as a base polymer in order to obtain a cured product of a rubber-like elastic body, and for this reason, the amount of acrylic group at the end is relatively very small. However, there is a drawback that the curability is poor and the surface portion in contact with air is hardly cured due to the inhibition of curing by oxygen. Therefore, as a photocurable composition of this kind, only a resin-like composition having a relatively large amount of an acrylic group has been put into practical use, and a composition capable of forming a cured product having a satisfactory rubber-like elasticity is known. Not not.
For example, the obtained cured product has a problem that it has a poor tensile strength and the composition itself has a poor storability.

Further, as a solution of the above-mentioned drawbacks of the photocurable organopolysiloxane composition, the present inventors have previously added a novel compound called an alkoxy-α-silyl ester to a (meth) acrylic functional group. A composition used in combination with an alkoxysilane, a divalent tin compound, a photopolymerization initiator and a curing catalyst was proposed.

However, although this composition has the advantage of providing a silicone rubber elastic body that can be used as a cured product, it has the problem that this cured product does not adhere to glass or metal at all, and various compositions are used. It turned out to be unsuitable for bonding and sealing. In order to improve the adhesiveness, it is possible to add an organosilicon compound having an amino group or an acryl group to the composition. In this case, the adhesiveness to glass is improved, but the metal or the like is improved. Adhesiveness to materials other than glass is still insufficient. Further, regarding the adhesiveness to glass, there is a drawback that it takes about several days to develop it.

Therefore, the object of the present invention is that it can be cured at room temperature in the presence of moisture, can be easily cured by UV irradiation, and has good storage stability. Another object of the present invention is to provide a curable organopolysiloxane composition capable of forming a rubber elastic cured product having excellent adhesiveness.

[0013]

According to the present invention, (A) the following general formula (1):

[Chemical 4] In the formula, R ¹ is the same or different, unsubstituted or substituted monovalent hydrocarbon group, and n is an integer of 1 to 10,000,
A terminal hydroxyorganopolysiloxane represented by: (B) the following general formula (2):

[Chemical 5] In the formula, R ² is a hydrogen atom or a methyl group, R ³ is a divalent organic group, R ⁴ and R ⁵ are the same or different unsubstituted or substituted monovalent hydrocarbon groups, and a is 0, (Meth) acryl-functional alkoxysilane represented by the formula, which is an integer of 1 or 2, (C) the following general formula (3): SnX ₂ (3) In the formula, X may be the same or different, and halogen. Atoms, alkoxy groups and carboxyl groups (-OOC-R:
R is at least one group selected from the group consisting of monovalent hydrocarbon groups, and (D) a divalent tin compound represented by the following general formula (4):

[Chemical 6] In the formula, R ⁸ and R ⁹ are a methyl group or an ethyl group, R ¹⁰
And R ¹¹ may be the same or different and each is a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group, R
¹² is an unsubstituted or substituted monovalent hydrocarbon group, b is
An alkoxy-, which is an integer of 0, 1 or 2.
Provided is a curable organopolysiloxane composition containing an α-silyl ester, (E) an alkenoxy group-containing silacyclo ring compound, (F) an onium salt compound (G) a photopolymerization initiator (H) a curing catalyst.

That is, the present inventors have conducted various studies to develop a curable organopolysiloxane composition having particularly excellent adhesiveness and storage stability, and as a result, the above-mentioned components (A) to (D)
When the components are mixed and the silacyclo ring compound having an alkenoxy group and the onium salt compound are added to the composition in which the photopolymerization initiator and the curing catalyst are added, the composition cures in a short time when irradiated with ultraviolet rays. However, the present invention has been completed by discovering that the adhesive strength is unexpectedly and unexpectedly exhibited, and that it can well adhere to glass, metal, plastic and the like.

The component (A) organopolysiloxane (A) is a base polymer, and the terminal hydroxyorganopolysiloxane represented by the general formula (1) is used for this. In the general formula (1), the unsubstituted or substituted monovalent hydrocarbon group R ¹ is preferably one having 1 to 10 carbon atoms, particularly 1 to 8 carbon atoms, specifically, a methyl group, an ethyl group or a propyl group. Group, alkyl group such as butyl group, alkenyl group such as vinyl group and allyl group, aryl group such as phenyl group and tolyl group, aralkyl group such as benzyl group and 2-phenylethyl group, or part of these hydrogen atoms Or a group in which all are substituted with halogen atoms,
Examples thereof include a chloromethyl group and a 3,3,3-trifluoropropyl group. In addition, n is 1 to 10
It is an integer of 000.

As is clear from the above general formula (1), this organopolysiloxane is linear and has hydroxyl groups bonded to both ends thereof. Suitable examples of such organopolysiloxanes include, but are not limited to, the following. In the following formulae, Me represents a methyl group, and Ph represents a substituted or unsubstituted phenyl group.

[Chemical 7]

(B) (Meth) acryl-functional alkoxysilane This (B) component, the (meth) acryl-functional alkoxysilane, imparts UV curability to this composition, for example by condensation, the base organo It is incorporated into polysiloxane and provides stable UV curability.

The above general formula (2) representing the alkoxylane
In, R ² is a hydrogen atom or a methyl group. R ³ is a divalent organic group, for example, an alkylene group can be exemplified, and one having 1 to 6 carbon atoms is particularly preferable. Further, R ⁴ and R ⁵ are each an unsubstituted or substituted monovalent hydrocarbon group, specifically, an alkyl group such as a methyl group, an ethyl group, a propyl group and a butyl group, and an aryl group such as a phenyl group. In particular, those having 1 to 8 carbon atoms are preferable. Further, in the general formula (2), a is an integer of 0, 1 or 2, and as understood from this number, the hydrocarbon group R ⁴ is not an essential group. Suitable examples of such alkoxysilanes include, but are not limited to, the following.

[0019]

[Chemical 8]

In the present invention, the (meth) acryl-functional alkoxysilane is used in an amount of 0.1 to 10 parts by weight, particularly 1 to 5 parts by weight, based on 100 parts by weight of the organopolysiloxane (A). Is desirable. 0.1
If it is less than 10 parts by weight, the ultraviolet curability of the composition will be deteriorated, and if it is used in an amount of more than 10 parts by weight, the rubber elasticity of the cured product will be impaired by the curing of only the (meth) acryl-functional alkoxysilane. This may cause inconvenience such as being lost.

(C) Divalent Tin Compound The divalent tin compound of the component (C) acts as a catalyst that selectively advances the condensation reaction of silanol and an alkoxy group, and generally ( It is preferably used in an amount of 0.01 to 5 parts by weight, particularly 0.1 to 3 parts by weight, based on 100 parts by weight of the component (A) organopolysiloxane. 0.
When the amount is less than 01 parts by weight, the ability as a catalyst is not sufficiently exhibited, and when the amount is more than 5 parts by weight,
This may cause inconvenience such as poor storage stability of the composition.

This divalent tin compound has the above general formula (3)
, And suitable examples thereof include, but are not limited to, the following. SnCl ₂ , SnBr ₂ , SnI ₂ , Sn (OOCCH
₃ ) ₂ , Sn (OOC) ₂ , Sn (OOCC
₇ H ₁₅ ) ₂ , Sn (OMe) ₂ , Sn (OOCC
₁₅ H ₃₁ ) ₂

(D) Alkoxy-α-silyl ester Since the alkoxy-α-silyl ester represented by the component (D) has an alkoxy, it acts as a cross-linking agent. Reacts with the organopolysiloxane to form a cured product and also acts as a dealcohol scavenger. By incorporating this alkoxy-α-silyl ester, the storage stability of the composition is improved.

As such an alkoxy-α-silyl ester, the one represented by the above general formula (4) is used. In this general formula (4), R ⁸ and R ⁹ are each a methyl group or an ethyl group, preferably a methyl group.

R ¹⁰ and R ¹¹ are each a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group. Examples of such a monovalent hydrocarbon group include a lower alkyl group having 4 or less carbon atoms such as a methyl group, an ethyl group, a propyl group and a butyl group, and a group obtained by substituting a part or all of the hydrogen atoms with a halogen atom. Is preferred.

Further, R ¹² is an unsubstituted or substituted monovalent hydrocarbon group, for example, an alkyl group having 8 or less carbon atoms, a phenyl group, and some or all of the hydrogen atoms of these groups are halogen atoms. Groups substituted with are preferred.

Suitable examples of such alkoxy-α-silyl esters include, but are not limited to:
The following can be illustrated.

[0028]

[Chemical 9]

[Chemical 10]

In the present invention, the above-mentioned alkoxy-α
The silyl ester is usually used in an amount of 0.1 to 10 parts by weight, especially 100 parts by weight of the organopolysiloxane (A).
It is preferably used in an amount of 0.5 to 10 parts by weight. 0.
When the amount is less than 1 part by weight, the storage stability of the composition is lowered, and when the amount is more than 10 parts by weight, the alkoxysilane which is not incorporated into the crosslinkage remains, so that the rubber elasticity of the cured product is impaired. This may cause inconvenience such as being lost.

(E) Silacyclo Ring Compound In the present invention, the alkenoxy group-containing silacyclo ring compound as the component (E) improves the adhesiveness of the composition. That is, since this compound has an alkenoxy group and further forms a ring, it exhibits extremely high reactivity with a compound having an active hydrogen atom such as alcohol.
For this reason, it has an effect of improving the surface characteristics of various substances, and can extremely effectively improve the adhesiveness of the composition to various substrates, such as glass, metals, and various plastics.

Examples of such silacyclo ring compounds include the following general formula (5) or (6):

[Chemical 11]

[Chemical 12] In the formula, R ¹³ may be the same or different and is a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group having 1 to 8 carbon atoms, and R ¹⁴ may be the same or different. , Hydrogen atom or unsubstituted or substituted carbon atom 1
A hydrocarbon group of 8 to 8 and Y is a divalent hydrocarbon group of 2 to 6 carbon atoms.

The above-mentioned silacyclo ring compound is represented by the following general formula (7):

[Chemical 13] Or the following general formula (8):

[Chemical 14] In the above formula, R ¹⁴ and Y are as described above, and are easily synthesized by reacting a compound represented by the formula with dichlorosilane or tetrachlorosilane for condensation cyclization. That is, when dichlorosilane is used, the organosilicon compound of the general formula (5) is obtained, and when tetrachlorosilane is used, the organosilicon compound of the general formula (6) is obtained. The above condensed ring cyclization reaction is preferably carried out using an alkali catalyst. Most preferred as such an alkali catalyst is triethylamine. The reaction temperature is generally 1
The range of 0 to 150 ° C. is suitable, and a suitable inert solvent is used in the reaction.

In the present invention, the following may be mentioned as typical examples of the silacyclo ring compound represented by the general formula (5).

[Chemical 15]

Further, as typical examples of the silacyclo ring compound represented by the general formula (6), the following can be exemplified.

[Chemical 16] In the above formula, Me is a methyl group, Et is an ethyl group, Pr
Is a propyl group, Vi is a vinyl group, and Ph is a phenyl group.

It is desirable that the above-mentioned silacyclocyclo compound is generally used in an amount of 0.1 to 10 parts by weight, particularly 0.1 to 5 parts by weight, per 100 parts by weight of the organopolysiloxane as the component (A). . If it is less than 0.1 part by weight, the adhesiveness of the composition may be lowered, and if it is used in excess of 10 parts by weight, the rubber elasticity of the cured product may be impaired.

(F) Onium Salt Compound The onium salt compound of component (F) is used in combination with the silacyclo ring compound of component (E) to improve the adhesiveness of the composition. This onium salt-based compound may be a compound known per se, for example, the aryl group is represented by Ar and has the following formula: (Ar) ₂ I ⁺ X ⁻ , (Ar) ₃ S ⁺ X ⁻ , (Ar) ₃ Se. ⁺ X ⁻ , (Ar) ₄ P ⁺ X ⁻ , (Ar) N ₂ ⁺ X ^−, where X ⁻ is SbF ₆ ⁻ , AsF ₆ ⁻ , PF ₆ ⁻ , B
A diaryliodonium salt, a triarylsulfonium salt, a triarylselenonium salt, a tetraarylphosphonium salt, which is a non-nucleophilic and non-basic anion such as F ₄ ⁻ , HSO ₄ ⁻ , ClO ₄ ⁻ , An aryl diazonium salt etc. can be illustrated. This onium salt-based compound is usually used in an amount of 0.01 to 40 parts by weight per 100 parts by weight of the organopolysiloxane (A),
Particularly, it is desirable to use it in an amount of 0.1 to 10 parts by weight. If the amount is less than 0.1 part by weight, the adhesiveness exhibited when the composition is irradiated with ultraviolet rays becomes poor, and if the amount is more than 40 parts by weight, the adhesiveness is improved but the surface condition of the cured film is adversely affected. , The rubber may deteriorate.

(G) Photopolymerization Initiator The photopolymerization initiator of the component (G) is for accelerating the photopolymerization of the acrylic group, which may be well known in the art. For example, acetophenone, propiophenone, benzophenone, xanthol, fluorein, benzaldehyde, anthraquinone, triphenylamine, 4-methylacetophenone, 3-pentylacetophenone, 4-methoxyacetophenone, 3-bromoacetophenone, 4-allylacetophenone, p. -Diacetylbenzene, 3-methoxybenzophenone, 4-
Methylbenzophenone, 4-chlorobenzophenone,
4,4-dimethoxybenzophenone, 4-chloro-4-
Benzylbenzophenone, 3-chloroxanthone,
3,9-dichloroxanthone, 3-chloro-8-nonylxanthone, benzoin, benzoin methyl ether, benzoin butyl ether, bis (4-dimethylaminophenyl) ketone, benzyl methoxy ketal, 2
-Chlorothioxanthone, diethyl acetophenone,
Examples thereof include 1-hydroxycyclohexyl phenyl ketone, 2-methyl- [4- (methylthio) phenyl] 2-morpholino-1-propanone, 2,2-dimethoxy-2-phenylacetophenone and diethoxyacetophenone.

It is desirable that the compounding amount is 0.01 to 10 parts by weight, particularly 0.1 to 5 parts by weight, based on 100 parts by weight of the above-mentioned component (A) organopolysiloxane. If the amount is less than 0.01 part by weight, the effect is not obtained
If the amount is more than 10 parts by weight, the silicone rubber obtained from this will have low strength and the physical properties of the cured product will tend to deteriorate.

The component (H), which is a curing catalyst (H), accelerates the curing of the component (D) with the alkoxy-α-silyl ester, and can be used, for example, in a silicone resin composition that is cured in the presence of moisture. Similar to those used, specifically tin-based catalysts,
A titanium-based catalyst or the like can be used. As the tin-based catalyst, dibutyltin diacetate, dibutyltin dioctate, dibutyltin dilaurate, dibutyltin dioleate,
Examples thereof include diphenyltin diacetate, dibutyltin oxide, dibutyltin dimethoxide, dibutylbis (triethoxysiloxy) tin, dibutyltin benzylmalate and the like. Further, as the titanium-based catalyst, titanic acid esters such as tetraisopropoxy titanium, tetra-n-butoxy titanium, tetrabis (2-ethylhexoxy) titanium, dipropoxybis (acetylacetona) titanium, titanium isopropoxyoctylene glycol, and the like, Mention may be made of titanium chelate compounds. Generally, this curing catalyst is composed of the organopolysiloxane 100 as the component (A).
It is used in an amount of 0.01 to 10 parts by weight, in particular 0.1 to 5 parts by weight, per part by weight.

Other compounding agents The composition of the present invention contains the above-mentioned components (A) to (H) as essential components, but within a range that does not impair the adhesiveness or storage stability thereof. It is also possible to use a compounding agent known per se. For example, in order to improve the mechanical properties of the resulting silicone rubber elastic body, a fumed silica-based filler that does not inhibit photocuring may be added, and further a thixotropy-imparting agent for the purpose of adjusting its physical properties, It is also possible to add a heat resistance improver, a coloring agent and the like.

The composition of the present invention can be obtained by uniformly mixing the above-mentioned components in the absence of water. The curable composition of the present invention thus obtained is cured at room temperature by the action of moisture in the atmosphere when exposed to the atmosphere. It also cures extremely quickly by irradiation with ultraviolet light. The obtained cured product is a silicone rubber elastic body having excellent properties such as heat resistance, weather resistance and low temperature properties, and is put to practical use in a wide range of fields. In particular, the cured product has excellent adhesiveness to glass, various metals, plastics, etc., and is not corrosive and does not generate an irritating odor. Therefore, it is extremely useful as an adhesive, a sealant, a coating agent, and a potting agent.

[0042]

EXAMPLES Next, examples of the present invention will be given. Parts in the examples are parts by weight, and viscosities are measured values at 25 ° C.

Example 1 Polydimethylsiloxane having both ends blocked with OH groups (viscosity 5,000 cP) 100 parts Fume-like silica 10 parts Methacryloxypropyltrimethoxysilane 1.7 parts Tin dioctoate 0.1 parts 2-tri 2-Ethylhexyl methoxysilylpropionate 3 parts Diethoxyacetophenone 2 parts Dibutyltin dilaurate 0.5 parts Diaryl iodonium salt 0.5 parts 2,4,4-Trimethyl-2-vinyl-6-methylene-
A curable composition was prepared by adding 0.5 part of 1,3-dioxa-2-silacyclohexane.

Then, this curable composition was irradiated with ultraviolet rays (irradiation energy amount: 1.5 J / cm ² ) at 1 m / mi by using an ultraviolet irradiation device ASE-20 (trade name of Nippon Battery Co., Ltd.).
Irradiate 3 times at a speed of n to cure this, 20 ± 3
The rubber physical properties were measured after 7 days at 55 ° C. and 55 ± 5% RH.

Further, a sample for measuring glass shear adhesive strength was prepared using the above-mentioned curable composition, cured under the same conditions as above, and the glass shear adhesive strength after 1 hour of curing was measured. The same measurement was carried out after heat storage for 7 days. The results are shown in Table 1.

Example 2 Cured in the same manner as in Example 1 except that the same amount of 2-ethyl 2-trimethoxysilylpropionate was used instead of 3 parts of 2-ethylhexyl 2-trimethoxysilylpropionate. A sex composition was prepared and a similar test was conducted. The results are shown in Table 1.

Comparative Example 1 In Example 1, the silacyclo ring compound (2,4,4-
A curable composition was prepared in the same manner except that trimethyl-2-vinyl-6-methylene-1,3-dioxa-2-silacyclohexane) was not used, and the same test was performed. The results are shown in Table 1.

Comparative Example 2 A curable composition was prepared in the same manner as in Example 1 except that the diaryl iodonium salt was not used, and the same test was conducted. The results are shown in Table 1.

Comparative Example 3 A curable composition was prepared in the same manner as in Example 1 except that the α-silyl ester (2-ethylhexyl 2-trimethoxysilylpropionate) was not used, and the same test was conducted. went. The results are shown in Table 1.

[0050]

[Table 1]

From this result, regarding the preservability, (D)
It was confirmed that the alkoxy-α-silyl ester as a component is an essential component in terms of adhesiveness, the silacyclo ring compound having an alkeno group as the component (E) and the onium salt compound as the component (F).

[0052]

EFFECT OF THE INVENTION The composition of the present invention cures in a short time when irradiated with ultraviolet rays, and also easily cures at room temperature due to the presence of moisture even when exposed to the atmosphere. The obtained silicone rubber cured product adheres well to glass, plastic and the like. Furthermore, this curable composition is excellent in storability due to the effect of the alkoxy-α-silyl ester which is the component (D). Therefore, the composition of the present invention is useful as an adhesive, a sealant, a coating agent, and a potting agent, and is not corrosive to metals and does not generate an irritating odor. Therefore, it is extremely useful in the field of electric and electronic parts. It is useful.

Claims (2)

[Claims] 1. (A) The following general formula (1): In the formula, R ¹ is the same or different unsubstituted or substituted monovalent hydrocarbon group, n is an integer of 1 to 10,000, and the terminal hydroxyorganopolysiloxane is represented by: (B) The following general formula (2) ): [Chemical 2] In the formula, R ² is a hydrogen atom or a methyl group, R ³ is a divalent organic group, R ⁴ and R ⁵ are the same or different unsubstituted or substituted monovalent hydrocarbon groups, and a is 0, (Meth) acryl-functional alkoxysilane represented by the formula, which is an integer of 1 or 2, (C) the following general formula (3): SnX ₂ (3) In the formula, X may be the same or different, and halogen. Atoms, alkoxy groups and carboxyl groups (-OOC-R:
R is at least one group selected from the group consisting of monovalent hydrocarbon groups, and (D) a divalent tin compound represented by the following general formula (4): In the formula, R ⁸ and R ⁹ are methyl groups or ethyl groups, R ¹⁰ and R ¹¹ may be the same or different, and each is a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group, and R ¹² is An unsubstituted or substituted monovalent hydrocarbon group, b is an integer of 0, 1 or 2, an alkoxy-α-silyl ester represented by: (E) an alkenoxy group-containing silacyclo ring compound (F) an onium salt A curable organopolysiloxane composition containing a compound (G) a photopolymerization initiator (H) a curing catalyst. 2. A cured product obtained by curing the composition according to claim 1.