JP7485496B2 - Curable silicone composition and its uses - Google Patents

Description

The present invention relates to a curable composition comprising a curable reactive organosiloxane and/or organopolysiloxane, a polysilsesquioxane having a cage molecular structure which may optionally have a curable reactive group, and a curing agent for curing the curable organosiloxane and/or organopolysiloxane, and in particular to a curable silicone composition having a cured product with a low dielectric constant. The curable silicone composition of the present invention has a low dielectric constant of less than 3.0 and is suitable as an insulating material for electronic and electric devices, in particular as a material for use as a coating agent.

Due to their high heat resistance and excellent chemical stability, silicone resins have been used as coating agents, potting agents, insulating materials, etc. for electronic and electric devices. Among silicone resins, curable silicone compositions containing silsesquioxanes consisting of T units (RSiO _3/2 , where R generally represents an alkyl group, an aryl group, etc.) as one component have also been reported.

International Publication No. 2015/064310 describes a photocurable silicone composition that contains a silsesquioxane compound having two or more polymerizable groups and a silicone compound having two or more polymerizable groups at the end in specific proportions, and also contains a photopolymerization initiator and a solvent, and describes the use of this composition as an imprint material for forming a film to which a predetermined pattern is transferred.

JP 2009-155442 A describes a resin composition for lenses that contains a cage-type silsesquioxane having two or more aliphatic unsaturated bonds in one molecule, an organohydrogenpolysiloxane having two or more SiH groups in one molecule, and an ethylenically unsaturated compound having two or more (meth)acrylic groups in one molecule, and that can be cured by a hydrosilylation reaction and a radical polymerization reaction.

JP 2007-332211 A describes a thermosetting polymer composition that contains a compound having a silsesquioxane skeleton as a repeating unit, a silsesquioxane derivative with a cage structure having a group such as 3,4-epoxycyclohexyl, and a curing agent, and describes the use of this composition as an insulating material for electric and electronic components. The curable composition described in the publication cures through a crosslinking reaction caused by the reaction between the epoxy group and the polyamine curing agent.

International Publication No. 2015/064310 JP 2009-155442 A JP 2007-332211 A

Colloids and Surfaces A: Physicochemical and Engineering Aspects, 522 (2017) 66-73

As described above, several curable compositions using polysilsesquioxanes, particularly cage-type polysilsesquioxanes, are known to date, but there is still a need for curable silicone compositions that have a low dielectric constant when cured and excellent workability, particularly low viscosity, when applied to a substrate. The present invention seeks to provide a novel curable composition that has a low dielectric constant when cured and also has excellent workability when applied to a substrate.

The present invention was developed based on the discovery that by incorporating a polysilsesquioxane having a cage molecular structure into a matrix obtained by crosslinking and curing an organosiloxane and/or organopolysiloxane having a crosslinkable group, the resulting cured product can have a low relative dielectric constant, and furthermore, this curable composition has low viscosity and is easy to work with when applied to a substrate.

In this specification, the term organo(poly)siloxane is used to mean organosiloxane and/or organopolysiloxane, and includes only organosiloxane, only organopolysiloxane, and a combination of organosiloxane and organopolysiloxane, and means that any one of them may be used.

The curable composition of the present invention comprises
(A) one or more curable reactive organo(poly)siloxanes;
(B) a polysilsesquioxane having a cage molecular structure, which may optionally have a curing reactive group; and (C) a curing agent for the curing reactive organo(poly)siloxane.

The curing reaction involving component (A), or, when component (B) has a curing reactive group, the curing reaction involving components (A) and (B), is preferably one or a combination of two or more reactions selected from a hydrosilylation reaction, a condensation reaction of a hydrolyzable silyl group and/or a silicon-bonded hydroxyl group, a radical polymerization reaction, and a peroxide crosslinking reaction of an organo(poly)siloxane.

When the curing reaction involving component (A) or the curing reaction involving components (A) and (B) when component (B) has a curing reactive group is a hydrosilylation reaction, the curing agent contains a hydrosilylation reaction catalyst; when the curing reaction involving component (A) or the curing reaction involving components (A) and (B) when component (B) has a curing reactive group is a condensation reaction of hydrolyzable silyl groups and/or silicon-bonded hydroxyl groups, the curing agent contains a condensation reaction catalyst; when the curing reaction involving component (A) or the curing reaction involving components (A) and (B) when component (B) has a curing reactive group is a radical reaction, the curing agent contains a radical initiator; and when the curing reaction involving component (A) or the curing reaction involving components (A) and (B) when component (B) has a curing reactive group is a peroxide crosslinking reaction of organo(poly)siloxane, the curing agent preferably contains an organic peroxide.

The curing reaction involving component (A), or, if component (B) has a curing reactive group, the curing reaction involving components (A) and (B), is preferably a hydrosilylation reaction.

Alternatively, it is preferred that the curing reaction involving component (A), or, if component (B) has a curing reactive group, the curing reaction involving components (A) and (B), is a condensation reaction of hydrolyzable silyl groups and/or silicon-bonded hydroxyl groups.

In one embodiment, it is preferred that component (B) has a curing reactive group, the curing reaction involving components (A) and (B) is a hydrosilylation reaction, component (A) is an organo(poly)siloxane having an alkenyl group-containing group, or an organo(poly)siloxane having a SiH group, or a combination thereof, component (B) is a polysilsesquioxane having a cage-like molecular structure having an SiH group, or a polysilsesquioxane having a cage-like molecular structure having an alkenyl group, the curing reactive groups of components (A) and (B) are selected so that components (A) and (B) can crosslink, and components (A) and (B) can crosslink by a hydrosilylation reaction, and the curing agent contains a hydrosilylation reaction catalyst.

In one embodiment, component (A) further contains an organo(poly)siloxane having a UV-curable functional group, and the curing reaction of component (A) is preferably carried out by a crosslinking reaction due to energy beam irradiation in addition to a hydrosilylation reaction, a condensation reaction of hydrolyzable silyl groups and/or silicon-bonded hydroxyl groups, a radical polymerization reaction, and/or a peroxide crosslinking reaction of the organo(poly)siloxane.

In one embodiment, the curing reaction of the curable composition is carried out by a combination of a hydrosilylation reaction and a crosslinking reaction caused by irradiation with energy rays.

In one embodiment, the curable composition can be cured at room temperature or by heating without the application of external energy rays, such as ultraviolet rays or electron beams, to promote the curing reaction.

Regarding the above component (B), the polysilsesquioxane having a cage molecular structure of (B) is represented by the following average unit formula (1):
( ^R9SiO3 _/2 ) _p ( ^R10SiO3 / ₂ ) _q ( _O1/ ^2Ra ) _r (2)
(In the formula, each R ⁹ is independently an unsubstituted or fluorine-substituted monovalent hydrocarbon group; R ¹⁰ is a curing reactive group; each R ^a is independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a cycloalkyl group having 5 to 20 carbon atoms; p, q, and r each represent the number of units, and either or both of q and r may be 0.)
It is preferable that the formula is represented by the formula:

In the above formula (2), it is preferred that each R ⁹ is independently an unsubstituted or fluorine-substituted alkyl group having 2 to 20 carbon atoms.

In the above formula (2), it is preferable that each R ¹⁰ is independently an alkenyl group having 2 to 20 carbon atoms. It is more preferable that each R ⁹ is independently an unsubstituted or fluorine-substituted alkyl group having 2 to 20 carbon atoms, and each R ¹⁰ is independently an alkenyl group having 2 to 20 carbon atoms.

In the above formula (2), it is preferred that q is 0 and the polysilsesquioxane of formula (2) does not have a curing reactive group R ¹⁰ bonded to a silicon atom.

It is preferred that the polysilsesquioxane having a cage molecular structure of component (B) has an average number of silicon atoms per molecule of 8 to 20, a number average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC) is in the range of 500 to 3,000, and a molecular weight dispersity ( _Mw / _Mn ) is 1.0 to 1.5.

In the above curable composition, the mass ratio of component (A) to component (B) is preferably (1-99):(99-1) (component (A):component (B)).

The curable composition of the present invention preferably has a viscosity in the range of 5 to 1,000 mPa.s at 25°C, and the dielectric constant of the cured product after curing is preferably less than 3.0, and more preferably less than 2.8.

The curable composition of the present invention is useful as a coating agent. Therefore, the present invention also provides a coating agent containing the curable composition.

The present invention also provides a method for using the cured product obtained from the above-mentioned curable composition as an insulating coating layer.

The present invention also provides a touch panel or a display device other than a touch panel, which includes a layer of a cured product obtained by curing the curable composition of the present invention.

The curable composition of the present invention has a suitable viscosity that provides good workability when applied to a substrate, and the cured product obtained from the composition has a low relative dielectric constant, and is therefore useful as an article including a low dielectric constant layer, particularly a low dielectric constant material for electronic devices, particularly a material for an insulating layer, and particularly a coating material, in any field in which a material having a low dielectric constant is used.

The configuration of the present invention will be described in further detail below.
The curable composition of the present invention includes the following components (A), (B), and (C). Component (C) is a compound for initiating or accelerating the curing reaction of the curing reactive groups of components (A) and (B) when component (A) or component (B) has a curing reactive group. In addition, an organic solvent may be added to the curable composition of the present invention if desired in order to reduce the viscosity of the composition, but the amount of the organic solvent is preferably less than 10% of the total mass of the composition, and more preferably, the composition of the present invention does not substantially contain an organic solvent. One of the features of the curable composition of the present invention is that the cured product obtained from the composition has a low relative dielectric constant. The reason why the relative dielectric constant of the cured product obtained from the curable composition of the present invention is low is not necessarily clear, but it is presumed that the polysilsesquioxane (component (B)) having a cage-shaped molecular structure dispersed in the matrix formed by crosslinking and curing component (A) or components (A) and (B) has nanoscale pores, which introduces nanoscale pores into the cured product, thereby lowering the relative dielectric constant. The curable composition of the present invention is useful as an insulating coating agent, particularly as a coating agent for forming insulating layers in electronic devices and electric devices, for example, display devices such as touch panels and displays, and components thereof, or semiconductor devices, taking advantage of the low dielectric constant and good workability of the cured product.

In the following description, the viscosity of the compound is a value measured by a rotational viscometer at 25°C (unit: mPa·s). The number average molecular weight and weight average molecular weight of the compound are values measured by gel permeation chromatography (GPC) in terms of polystyrene. The relative dielectric constant is a value measured by the capacitance method (capacitor method) at 23°C.

[ Component (A): Curable Reactive Organo(poly)siloxane ]
The curing reactive organo(poly)siloxane used as component (A) has a crosslinkable group or a crosslinkable curing reactive group, and is capable of curing the entire composition by a reaction between the curing reactive groups of component (A), or, if component (B) has a curing reactive group and the curing reactive group is capable of undergoing a curing reaction with the curing reactive group of component (A), by a reaction between the curing reactive groups of component (A) or between the curing reactive groups of component (A) and component (B), and its chemical structure is not particularly limited as long as the purpose can be achieved. The term "curing reactive group" as used herein includes both relatively highly reactive functional groups that are generally recognized as crosslinkable or crosslinkable groups capable of causing a curing reaction of the composition, such as alkenyl groups and SiH groups in a hydrosilylation reaction, and carbon-carbon double bonds in a radical reaction, and groups that are not generally recognized as crosslinking reactive groups active enough to cause a curing reaction of the composition, but that can crosslink molecules together by abstraction of hydrogen by an active curing agent, such as an organic peroxide (for example, a hydrogen atom of a methyl group bonded to a silicon atom of an organo(poly)siloxane when crosslinking with an organic peroxide).

As the curing reactive group of component (A), it is preferable to use any curing reactive group selected from hydrosilylation reactive groups, radical reactive groups, condensation reactive groups, peroxide crosslinking reactions, and groups that can react upon irradiation with energy rays. In particular, curing reactive groups include hydrosilylation reactive groups or radical reactive groups having a carbon-carbon double bond; hydrosilylation reactive groups having a silicon-bonded hydrogen group (Si-H); condensation reactive groups selected from hydroxyl groups, alkoxy groups, acyloxy groups, and oximoxy groups; photoreactive groups that can undergo a crosslinking reaction upon irradiation with energy rays, such as groups selected from photoradical polymerizable groups and photocationic polymerizable groups; hydrocarbon groups bonded to silicon atoms that can undergo a crosslinking reaction by abstraction of hydrogen atoms by organic peroxides, such as methyl groups; or any combination thereof. Component (A) used in the present invention may be an organo(poly)siloxane containing one type of curing reactive group in the molecule, or may be an organopolysiloxane having two or more different types of curing reactive groups, or may be a mixture of two or more organo(poly)siloxanes that differ from each other in either the type of curing reactive group, the bonding site of the curing reactive group, the content of the curing reactive group, or the siloxane skeleton.

Preferred examples of component (A) include:
(i) one selected from organo(poly)siloxanes (A1) having a group containing a carbon-carbon double bond capable of participating in a hydrosilylation reaction and organohydrogen(poly)siloxanes (A2) having silicon-bonded hydrogen (Si—H), or a combination of (A1) and (A2);
(ii) an organo(poly)siloxane having a hydrolytically condensable silyl group capable of participating in a condensation reaction;
(iii) an organo(poly)siloxane having a group containing a radical polymerization reactive group capable of participating in a radical polymerization reaction (excluding the case of (v));
(iv) organo(poly)siloxanes having a curing reactive group capable of participating in a peroxide crosslinking reaction, and (v) organo(poly)siloxanes having a curing reactive group capable of participating in a crosslinking reaction by irradiation with energy rays, generally known as actinic rays, such as ultraviolet rays or electron beams.

As component (A), only one of the above (i) to (v), especially (i) to (iv), can be used, or two or more of each group of (i) to (v), especially one or more of the group of (i) to (iv), can be used in combination with the organo(poly)siloxane (v). In other words, the curing reactive groups possessed by component (A) can be those involved in only one type of curing reaction, or two or more different types of curing reactive groups can be used in combination. Preferred examples of such combinations include, but are not limited to, a combination of one or more of (i) to (iv) with (v).

(i) Component (A) Curable by a Hydrosilylation Reaction
When component (A) is an organo(poly)siloxane that has a curing reactive group participating in a hydrosilylation reaction and is curable by a hydrosilylation reaction, component (A) includes one selected from the following components (A1) and (A2), or both (A1) and (A2).
(A1) an organo(poly)siloxane having a curing reactive group containing a carbon-carbon double bond;
(A2) Organohydrogen(poly)siloxane having a silicon-bonded hydrogen atom (Si—H) as a curing reactive group.
When the curable composition contains only one of the components (A1) and (A2) as component (A), a polysilsesquioxane having a curing reactive group containing a carbon-carbon double bond or a silicon-bonded hydrogen atom (Si-H) capable of undergoing a hydrosilylation reaction with component (A) is used as component (B), thereby allowing the entire curable composition to be cured.

Component (A1) is an organo(poly)siloxane having a curing reactive group containing a carbon-carbon double bond, and is preferably a linear, branched, cyclic, or resinous (network) organo(poly)siloxane containing a curing reactive group in the molecule selected from the group consisting of alkenyl groups having 2 to 20 carbon atoms, such as vinyl groups, allyl groups, butenyl groups, pentenyl groups, hexenyl groups, heptenyl groups, octenyl groups, nonenyl groups, decenyl groups, undecenyl groups, dodecenyl groups, and 4-vinylphenyl groups; acrylic-containing groups, such as 3-acryloxypropyl groups and 4-acryloxybutyl groups; and methacrylic-containing groups, such as 3-methacryloxypropyl groups and 4-methacryloxybutyl groups. In particular, organo(poly)siloxanes having a curing reactive group containing a carbon-carbon double bond selected from vinyl groups, allyl groups, and hexenyl groups are preferred as component (A1).

The organo(poly)siloxane of component (A1) may contain, in addition to a group containing a carbon-carbon double bond, a group selected from the group consisting of a monovalent hydrocarbon group having no carbon-carbon double bond in the molecule, a hydroxyl group, and an alkoxy group. In addition, some of the hydrogen atoms of the monovalent hydrocarbon group may be substituted with halogen atoms or hydroxyl groups. Examples of such monovalent hydrocarbon groups include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl; aryl groups such as phenyl, tolyl, xylyl, naphthyl, anthracenyl, phenanthryl, and pyrenyl; aralkyl groups such as benzyl, phenethyl, naphthylethyl, naphthylpropyl, anthracenylethyl, phenanthrylethyl, and pyrenylethyl; and groups in which the hydrogen atoms of these aryl or aralkyl groups are replaced with alkyl groups such as methyl and ethyl; alkoxy groups such as methoxy and ethoxy; and halogen atoms such as chlorine and bromine. When component (A1) contains a condensable functional group such as a hydroxyl group and/or an alkoxy group, component (A1) has condensation reactivity in addition to hydrosilylation reaction curability.

Preferably, component (A1) has the following average composition formula:
R ¹¹ _a R ¹² _b SiO _(4-a-b)/2
or a mixture of two or more thereof.
wherein R ¹¹ is a curing reactive group containing a carbon-carbon double bond as described above;
R ¹² is a group selected from the group consisting of the monovalent hydrocarbon groups having no carbon-carbon double bonds, hydroxyl groups, and alkoxy groups.
a and b are numbers that satisfy the following conditions: 1≦a+b≦3 and 0.001≦a/(a+b)≦0.33, and preferably are numbers that satisfy the following conditions: 1.5≦a+b≦2.5 and 0.005≦a/(a+b)≦0.5. This is because when a+b is equal to or greater than the lower limit of the above range, the flexibility of the cured product is increased, whereas when it is equal to or less than the upper limit of the above range, the mechanical strength of the cured product is increased, and when a/(a+b) is equal to or greater than the lower limit of the above range, the mechanical strength of the cured product is increased, whereas when it is equal to or less than the upper limit of the above range, the flexibility of the cured product is increased.

In the curable composition of the present invention, the component (A1) is particularly preferably
(A1-1) a linear organo(poly)siloxane having alkenyl groups only at the molecular chain terminals, and
(A1-2) Contains one or more organopolysiloxanes containing an average of three or more alkenyl groups per molecule, with the vinyl (CH ₂ ═CH-) group content being within the range of 1.0 to 32.0 mass%, and may contain both component (A1-1) and component (A1-2).

The component (A1-1) has at its molecular chain end a (Alk)R ¹² ₂ SiO _1/2
(In the formula, Alk is an alkenyl group having 2 or more carbon atoms, and R ¹² is as defined above.)
and other siloxane units are linear organo(poly)siloxanes consisting essentially of siloxane units represented by R ¹² ₂ SiO _2/2 . Here, R ¹² represents a group as defined above. The degree of siloxane polymerization of component (A1-1) is preferably in the range of 5 to 1000, including the terminal siloxane units. Such component (A1-1) is particularly preferably a linear organo(poly)siloxane in which both ends of the molecular chain are blocked with siloxane units represented by (Alk)R ¹² ₂ SiO _1/2 .

Component (A1-2) is an organopolysiloxane containing an average of three or more alkenyl groups per molecule,
Average unit formula:
( ^R21SiO3 _/2 ) _o ( ^R22SiO2 / ₂ ) _p ( ^R23SiO1 _{/ 2} ) _q ( _{SiO4/2 ) r} (XO1 _/2 ) _s
It is preferable that the organopolysiloxane resin is an alkenyl group-containing organopolysiloxane resin represented by the following formula:
In the above formula, R ²¹ , R ²² , and R ²³ are groups selected from alkenyl groups and the above-mentioned monovalent hydrocarbon groups not having a carbon-carbon double bond, and X is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, provided that, among all the substituents on silicon atoms, at least a portion of R ²¹ , R ²² , and R ²³ are alkenyl groups so that the content of vinyl (CH ₂ ═CH—) groups in the organopolysiloxane falls within the range of 1.0 to 32.0 mass%, and in particular, it is preferred that at least a portion of R ²³ on the siloxane unit represented by R ²³ ₃ SiO _1/2 is an alkenyl group.

In the above formula, (o+r) is a positive number, p is 0 or a positive number, q is 0 or a positive number, s is 0 or a positive number, and it is preferable that p/(o+r) is a number in the range of 0 to 10, q/(o+r) is a number in the range of 0 to 5, (o+r)/(o+p+q+r) is a number in the range of 0.3 to 0.9, and s/(o+p+q+r) is a number in the range of 0 to 0.4.

Particularly preferred examples of component (A1-2) include
{(Alk) ^R232SiO1 _{/ 2} } _q1 ( ^R233SiO1 _{/2 ) q2} ( _SiO4/2 ) _r
(In the formula, Alk and ^R23 are the groups defined above, q1+q2+r is a number in the range of 5 to 500, (q1+q2)/r is a number in the range of 0.1 to 4.0, and q2 is a number in which the content of vinyl ( _CH2 =CH-) groups in the organopolysiloxane resin is in the range of 1.0 to 32.0 mass%.)
Examples of the alkenyl-containing MQ organopolysiloxane include those represented by the following formula:

These components (A1-1) having alkenyl groups only at the molecular chain terminals, and organopolysiloxane component (A1-2) containing three or more alkenyl groups and a vinyl (CH ₂ ═CH—) group content of 1.0 mass% or more can each be used alone, but by using them in combination, a cured reaction product having excellent fast-curing/fast-drying properties as a whole composition, as well as excellent mechanical strength and flexibility, can be obtained.

The organohydrogen(poly)siloxane (A2) having silicon-bonded hydrogen atoms (Si-H) is preferably a component that has at least two silicon-bonded hydrogen atoms in the molecule and functions as a crosslinking agent for component (A1) having a curing reactive group having a carbon-carbon double bond and/or component (B) having a curing reactive group containing a carbon-carbon double bond. In the present invention, when component (B) has a curing reactive group containing a carbon-carbon double bond such as the alkenyl group, the entire composition including component (B) can be cured by a hydrosilylation reaction by using component (A2), and such an embodiment is preferable. When component (B) having a curing reactive group containing a carbon-carbon double bond is used, the use of the above-mentioned component (A1) is optional, that is, component (A1) may be used in addition to such component (B), or component (A1) may not be used.

Examples of such component (A2) include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, tris(dimethylhydrogensiloxy)methylsilane, tris(dimethylhydrogensiloxy)phenylsilane, tetrakis(dimethylhydrogensiloxy)silane, methylhydrogenpolysiloxane capped at both molecular chain terminals with trimethylsiloxy groups, and dimethylsiloxane-methylhydrogensiloxane capped at both molecular chain terminals with trimethylsiloxy groups. copolymers, dimethylpolysiloxanes terminated at both molecular chain ends with dimethylhydrogensiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymers terminated at both molecular chain ends with dimethylhydrogensiloxy groups, methylhydrogensiloxane-diphenylsiloxane copolymers terminated at both molecular chain ends with trimethylsiloxy groups, methylhydrogensiloxane-diphenylsiloxane-dimethylsiloxane copolymers terminated at both molecular chain ends with trimethylsiloxy groups, hydrolysis condensates of trimethoxysilane, (CH _{Examples of} the copolymer include a copolymer consisting of ( _CH3 ) _{2HSiO1 /2} units, ( _CH3 )3SiO1 _{/2 units} , and SiO4 _/2 units, a copolymer consisting of ( _CH3 )2HSiO1 _{/ 2} units and ( _C6H5 )SiO3 _{/ 2} units, a copolymer consisting of ( _CH3 ) _{2HSiO1 /2 units} , SiO4 _{/2 units} , and ( _C6H5 ) _{SiO3 /2} units, and a mixture of two or more selected from these.

In the curable composition of the present invention, component (A2) is
It is preferred that the composition contains (A2-1) a linear organohydrogen(poly)siloxane having silicon-bonded hydrogen atoms only at the molecular chain terminals, and optionally contains (A2-2) a linear or resinous organohydrogenpolysiloxane having at least three silicon-bonded hydrogen atoms in the molecule.

Component (A2-1) is an organohydrogen(poly)siloxane having silicon-bonded hydrogen atoms only at the molecular chain terminals, and functions as a chain extender in the hydrosilylation reaction with component (A1) above, thereby increasing the flexibility of the cured reaction product. Component (A2-1) is preferably a linear organohydrogen(poly)siloxane, and particularly preferred examples include those represented by the following structural formulas, and it is preferable to use one or a mixture of two or more selected from these.
_HMe2SiO ( _Ph2SiO ) _{m1 SiMe2H
HMe2SiO} ( _{Me2SiO ) m1SiMe2H
HMe2SiO} ( _MePhSiO ) _{m1SiMe2H
HMe2SiO} ( _Me2SiO ) _{m1 (} MePhSiO) _{n1SiMe2H
HMe2SiO} ( _Me2SiO ) _{m1 ( Ph2SiO} ) _n1SiMe2H
HMePhSiO( _Ph2SiO ) _m1SiMePhH
HMePhSiO( _Me2SiO ) _m1SiMePhH
HMePhSiO( _Ph2SiO ) _m1 (MePhSiO) _n1 SiMePhH
HMePhSiO( _Ph2SiO ) _m1 ( _Me2SiO ) _n1SiMePhH
In the above formulas, Me and Ph represent a methyl group and a phenyl group, respectively; m1 is a number from 1 to 100; and n1 is a number from 1 to 50.

The above-mentioned component (A2-2) is a linear or resinous organohydrogenpolysiloxane having an average of at least three silicon-bonded hydrogen atoms per molecule, and is a component that can impart rapid curing properties to the composition when used in combination with the above-mentioned component (A2-1).

Examples of linear organohydrogen(poly)siloxanes used as component (A2-2) include methylhydrogenpolysiloxanes with both molecular chain terminals blocked by trimethylsiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymers with both molecular chain terminals blocked by trimethylsiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymers with both molecular chain terminals blocked by dimethylhydrogensiloxane, methylhydrogensiloxane-diphenylsiloxane copolymers with both molecular chain terminals blocked by trimethylsiloxy groups, and methylhydrogensiloxane-diphenylsiloxane-dimethylsiloxane copolymers with both molecular chain terminals blocked by trimethylsiloxy groups.

Examples of resinous organohydrogen(poly)siloxanes used as component (A2-2) include M _{H MQ} type, ^M _H Q type, M ^H _MT type _{, M H} ^T type, M ^H _MQT type, M ^{H QT} type ^, M ^{H MDQ} type, M ^{H MDD H Q type, M H} _DQ ^{type ,} M ^{H DD H} Q type, ^{M H H MH ...} Examples of organohydrogenpolysiloxane resins include one or more types selected from the ^{group consisting} of ^MDT type, ^MHMDDHT type, ^MHDT type, ^MHDDHT type, ^MHMDQT type, ^MHMDDHQT type, ^MHDQT type ^, and ^MHDDHQT type.
In the above formulas, R ³¹ is independently a methyl group or a phenyl group.

In the curable composition of the present invention, the content of component (A2) is preferably an amount in which the silicon-bonded hydrogen atoms in component (A2) are in the range of 0.1 to 10 moles per mole of carbon-carbon double bonds in component (A1), more preferably an amount in the range of 0.2 to 5.0 moles, and particularly preferably an amount in the range of 0.5 to 2.0 moles. If the amount of silicon-bonded hydrogen atoms in component (A2) is equal to or less than the lower limit of the aforementioned range, the curable composition may not cure properly. If the amount of silicon-bonded hydrogen atoms in component (A2) exceeds the upper limit of the aforementioned range, the cured product obtained by curing the composition may be too hard or the remaining (A2) may phase-separate from the cured product, which is not preferable when attempting to obtain an elastic or gel-like cured product.

In the curable composition of the present invention, when a polysilsesquioxane having a carbon-carbon double bond as a curing reactive group is used as component (B), the content of component (A2) is preferably an amount such that the number of silicon-bonded hydrogen atoms in component (A2) is in the range of 0.1 to 10 moles per mole of the total carbon-carbon double bonds in components (A1) and (B) in the composition, more preferably an amount in the range of 0.2 to 5.0 moles, and particularly preferably an amount in the range of 0.5 to 2.0 moles. Furthermore, when a polysilsesquioxane having silicon-bonded hydrogen atoms as curing reactive groups is used as component (B), the content of component (A2) is preferably an amount in which the total of silicon-bonded hydrogen atoms in components (A2) and (B) is in the range of 0.1 to 10 moles per mole of total carbon-carbon double bonds in component (A1) in the composition, more preferably an amount in the range of 0.2 to 5.0 moles, and particularly preferably an amount in the range of 0.5 to 2.0 moles.

(ii) Component (A) that is curable by a condensation reaction of hydrolyzable silyl groups and/or silicon-bonded hydroxyl groups
Instead of or in combination with the above (i) component (A) capable of being cured by a hydrosilylation reaction, component (A3) capable of being cured by a condensation reaction of hydrolyzable silyl groups and/or silicon-bonded hydroxyl groups can be used as component (A). That is, a part or all of component (A) may be (A3) an organo(poly)siloxane having a condensation reactive group as described above, and in particular may be organo(poly)siloxane (A3-1) consisting of one or more types of organo(poly)siloxanes having condensation reactive groups only at the molecular chain terminals, or a combination thereof. The condensation reactive group may be any group capable of crosslinking molecular chains of an organo(poly)siloxane by a condensation reaction or by hydrolysis and condensation reaction, and the type is not particularly limited, but preferred condensation reactive groups include groups selected from hydroxyl groups bonded to silicon atoms in the organo(poly)siloxane, alkoxy groups (e.g., methoxy groups, 2-propenyloxy groups), acyloxy groups (e.g., acetyloxy groups), and ketoxime groups (e.g., methyl ethyl ketoxime groups), or combinations of two or more groups selected therefrom. Organo(poly)siloxanes that can be cured by a condensation reaction of a hydrolyzable silyl group are well known in the art, and a person skilled in the art would be able to adjust the degree of polymerization, etc. of the organopolysiloxane to obtain an appropriate viscosity and to appropriately adjust the type and number of condensation reactive groups per molecule in accordance with the purpose of the present invention, and use them as component (A) of the present invention. The silicon-bonded groups other than the condensation reactive groups contained in the organo(poly)siloxane are preferably monovalent hydrocarbon groups having 1 to 20 carbon atoms, and are particularly preferably methyl and/or phenyl groups.

(iii) Organo(poly)siloxane component (A) having a radical polymerization reactive group as a curing reactive group
Instead of or in combination with the hydrosilylation-curable component (A) of (i) above, an organo(poly)siloxane having a radically polymerizable group-containing group can be used as component (A). That is, a part or all of component (A) may be (A4) an organo(poly)siloxane having a radically polymerizable group-containing group, and in particular, it may be an organo(poly)siloxane (A4-1) consisting of one or more types of organo(poly)siloxanes having radically polymerizable groups only at the molecular chain terminals, or a combination thereof. The radically polymerizable group may be any functional group known as an organic group polymerizable by a radical reaction, and may be any radically polymerizable group capable of curing the composition of the present invention by crosslinking the molecular chain of the organo(poly)siloxane by a radical reaction. Examples of radically polymerizable groups that can be used in the present invention include acryloxy or methacryloxy group-containing groups, such as acryloxypropyl groups, methacryloxypropyl groups, and terminal alkenyl groups, such as styryl groups and allylphenyl groups. In particular, acryloxypropyl groups are preferred due to their high reactivity to radical polymerization. A person skilled in the art can adjust the degree of polymerization of the organo(poly)siloxane to an appropriate viscosity and appropriately adjust the type and number of radical polymerization reactive groups per molecule in accordance with the object of the present invention, and use the organo(poly)siloxane as component (A) of the present invention. The silicon atom-bonded group other than the radically polymerizable reactive group contained in the organo(poly)siloxane is preferably a monovalent hydrocarbon group having 1 to 20 carbon atoms, and is particularly preferably a methyl group and/or a phenyl group.

As an embodiment in which the radical polymerization reaction and the addition reaction are used in combination, an organo(poly)siloxane having an acryloxypropyl group as the above-mentioned radical polymerization reactive group can be used in combination with an organo(poly)siloxane having an SH group, for example a mercaptopropyl group.

(iv) an organo(poly)siloxane component (A) having a curing reactive group capable of curing by intermolecular crosslinking reaction via peroxide crosslinking;
Instead of or in combination with the component (A) that can be cured by the hydrosilylation reaction (i) above, an organo(poly)siloxane having a curing reactive group that can be cured by intermolecular crosslinking reaction by peroxide crosslinking can be used as the component (A). That is, a part or all of the component (A) may be (A5) an organo(poly)siloxane having a curing reactive group that can be cured by intermolecular crosslinking reaction by peroxide crosslinking. The curing reactive group that can be crosslinked between molecules by peroxide crosslinking also includes monovalent saturated hydrocarbon groups such as methyl groups bonded to silicon atoms of the organo(poly)siloxane, but it is preferable to use the above-mentioned component (A1-1) and/or component (A1-2) having an alkenyl group because the reactivity to peroxide crosslinking is high. Those skilled in the art can use the component (A1-1) and/or component (A1-2) by adjusting the content of the alkenyl group to an amount suitable for peroxide crosslinking.

(v) Organo(poly)siloxane component (A) having an ultraviolet-curable group as a curing reactive group
Instead of the component (A) that can be cured by the hydrosilylation reaction (i) above, preferably in combination with it, an organo(poly)siloxane having an ultraviolet curable group can be used as the component (A). That is, a part or all of the component (A), preferably a part, may be (A6) an organo(poly)siloxane having an ultraviolet curable group. The term "ultraviolet curable group" refers to a functional group that can cure the curable composition of the present invention by irradiation with ultraviolet light, but this functional group can also be reacted by energy rays such as electron beams other than ultraviolet light, and the curing of the organo(poly)siloxane having an ultraviolet curable group can be carried out under conditions that can cause a desired curing reaction, not limited to ultraviolet light, and this is also within the scope of the present invention.

で表すことができる。 The organo(poly)siloxane having an ultraviolet-curable group (A6) has, on average, two or more ultraviolet-curable groups per molecule, and may have any molecular structure as long as this purpose can be achieved. In general, the organo(poly)siloxane of component (A6) is represented by the following formula (1):

It can be expressed as:

In formula (1), among all the R ¹ to R ⁸ groups, two or more per molecule are ultraviolet curable groups on average. The ultraviolet curable groups are organic groups that can form bonds between each other by irradiation with ultraviolet light in the presence or absence of a photoinitiator. Examples of ultraviolet curable groups include radical reactive groups and cation reactive groups. The radical reactive groups are not particularly limited as long as they are functional groups that can form new bonds, particularly bonds between radical reactive groups, by a radical reaction mechanism. For example, groups that can be used alone include an acrylic group, a methacrylic group, a maleimide group, and an organic group containing any of these groups. In addition, functional groups that can be used in combination include a combination of an alkenyl group and an SH group. Specific examples include groups such as acryloxypropyl, methacryloxypropyl, acrylamidepropyl, methacrylamidepropyl, and 3-(N-maleimide)propyl that can be used alone as radical polymerizable groups, while a vinyl group and a mercaptopropyl group can also be used in combination. Examples of the cationically polymerizable group include groups such as a vinyl ether group, an epoxy group-containing group, and an oxetane group-containing group, for example, _CH2 =CH-O-( _CH2 )n- (n is an integer from 3 to 20), glycidyloxy-( _CH2 ) _n- (n is an integer from 3 to 20), and 3,4-epoxycyclohexyl-( _CH2 ) _n- (n is an integer from 2 to 20).
The ultraviolet-curable group is preferably one or more groups selected from epoxy group-containing groups and maleimide group-containing groups. Particularly preferred groups include an epoxycyclohexylethyl group, in particular a 3,4-epoxycyclohexylethyl group, and a 3-(N-maleimide)propyl group.

In formula (1), R ¹ to R ⁸ other than the ultraviolet curable group are each independently selected from unsubstituted or fluorine-substituted monovalent hydrocarbon groups, preferably unsubstituted or fluorine-substituted alkyl, cycloalkyl, arylalkyl, and aryl groups having 1 to 20 carbon atoms. Examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, sec-butyl, pentyl, and octyl groups, with methyl being particularly preferred. Examples of the cycloalkyl group include cyclopentyl and cyclohexyl. Examples of the arylalkyl group include benzyl and phenylethyl groups. Examples of the aryl group include phenyl and naphthyl groups. Examples of the monovalent hydrocarbon group substituted with fluorine include 3,3,3-trifluoropropyl. However, since the monovalent hydrocarbon group substituted with fluorine increases the relative dielectric constant of the cured product, it is preferable that it is not included in component (A) for the purposes of the present invention.

The number of UV-curable groups contained in the organo(poly)siloxane of formula (1), which is component (A), is not particularly limited, but the average number per molecule as a whole is 2 to 4, preferably 2 to 3, and particularly preferably 2.

In particular, it is preferred that one of R ₁ to R ₃ and one of R ₆ to R ₈ in formula (1) is an ultraviolet-curable group. Furthermore, it is particularly preferred that only one of R ₁ to R ₃ and one of R ₆ to R ₈ in formula (1) is an ultraviolet-curable group.

In formula (1), n is preferably a value that gives the organo(poly)siloxane of formula (1) a viscosity at 25°C of 1 to 10,000 mPa·s, more preferably a value that gives 1 to 2,000 mPa·s, and particularly preferably a value that gives 1 to 1,000 mPa·s. A person skilled in the art can easily determine the value of n so that the viscosity of the organo(poly)siloxane of formula (1) falls within the aforementioned viscosity range without the need for excessive trial and error. However, in general, the number of n is preferably 0 to 500, more preferably in the range of 0 to 100, so that the compound of formula (1) has the desired viscosity.

The organo(poly)siloxane of formula (1) can be used alone or as a mixture of two or more. When two or more organo(poly)siloxanes are used as a mixture, the viscosity of the mixture at 25°C is preferably 1 to 10,000 mPa·s, more preferably 1 to 2,000 mPa·s, and particularly preferably 1 to 1,000 mPa·s.

[ Component (B): Polysilsesquioxane having a cage-shaped molecular structure ]
The polysilsesquioxane having a cage molecular structure used as component (B) has the following average unit formula (2):
( ^R9SiO3 _/2 ) _p ( ^R10SiO3 / ₂ ) _q ( _O1/ ^2Ra ) _r (2)
Among polysilsesquioxanes consisting only of T units represented by the following formula (1), those having a cage molecular structure in particular have a cage molecular structure. Polysilsesquioxanes having a cage molecular structure have a so-called polyhedral cluster structure or a structure similar thereto, and are also called polyhedral oligomeric silsesquioxanes.

In formula (2), R ⁹ is a non-curing reactive group, each independently being an unsubstituted or fluorine-substituted monovalent hydrocarbon group, preferably an unsubstituted or fluorine-substituted group selected from an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an arylalkyl group having 7 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms. Examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, sec-butyl, pentyl, octyl, decyl, dodecyl, and tetradecyl groups. Examples of the cycloalkyl group include cyclopentyl and cyclohexyl. Examples of the arylalkyl group include benzyl and phenylethyl groups. Examples of the aryl group include phenyl and naphthyl groups. Particularly preferred monovalent hydrocarbon groups are alkyl groups having 2 to 20 carbon atoms, with hexyl, octyl, and decyl groups being particularly preferred. Examples of fluorinated monovalent hydrocarbon groups include 3,3,3-trifluoropropyl and 3,3,4,4,5,5,6,6,6-nonafluorohexyl, with 3,3,3-trifluoropropyl being preferred. In order to reduce the dielectric constant of the cured product obtained from the curable composition of the present invention, the polysilsesquioxane used in the present invention is preferably one with high molecular symmetry, and therefore, it is preferred that all of R ⁹ in formula (2) are the same group. This is because, for the compound of formula (2), it is advantageous to suppress the polarizability in the molecule by carrying out a molecular design that is symmetric or highly symmetric depending on the type of functional group or the arrangement in the molecule, in order to reduce the dielectric constant of the cured product obtained. Component (B) is a component that reduces the dielectric constant of the cured product obtained from the curable composition of the present invention.

In formula (2), R ¹⁰ is a curing reactive group and is an optional functional group in component (B). That is, as the compound represented by formula (2), both those in which R ¹⁰ is present and those in which R ¹⁰ is not present can be used as component (B) of the present invention. Examples of suitable curing reactive groups include functional groups that can be used as the curing reactive group of component (A) described above. Specific examples include: (a) groups containing a carbon-carbon double bond, such as vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, 4-vinylphenyl, 3-acryloxypropyl, and 3-methacryloxypropyl; (b) groups containing silicon-bonded hydrogen atoms (Si-H) and Si-H groups; (c) condensation-reactive groups, such as silicon-bonded hydroxyl groups, alkoxy groups (e.g., methoxy and 2-propenyloxy groups), acyloxy groups (e.g., acetyloxy groups), and ketoxime groups; (d) acryloxypropyl, methacryloxypropyl, acrylamidopropyl, methacrylamidepropyl, and 3-(N-maleimido)propyl, CH ₂ ═CH-O-(CH ₂ ) n - (n is an integer from 3 to 20), and 3,4-epoxycyclohexyl-(CH ₂ ) _{n .} Examples of such groups include ultraviolet-curable groups such as - (n is an integer from 2 to 20) and glycidyloxy-( _CH2 ) _n- (n is an integer from 3 to 20), (e) radically polymerizable groups such as an acryloxypropyl group and a styryl group, and (f) groups that can cause an intermolecular crosslinking reaction by peroxide crosslinking, for example, an alkenyl group.

In formula (2), it is preferred that each R ⁹ is independently an unsubstituted or fluorine-substituted alkyl group having 2 to 20 carbon atoms. It is also preferred that each R ¹⁰ is independently an alkenyl group having 2 to 20 carbon atoms. It is even more preferred that R ⁹ and R ¹⁰ satisfy both of the above requirements. This is particularly true when the curing reaction of component (A) is a hydrosilylation reaction.

In one embodiment of the present invention, the polysilsesquioxane represented by formula (2) does not have a curing reactive group. Therefore, in that case, the composition of the present invention is cured only by the action of the curing reactive group of component (A) and the curing agent of component (C). When the compound of formula (2) has a curing reactive group, depending on the type of curing reactive group possessed by the organo(poly)siloxane of component (A) and the type of curing reactive group possessed by the polysilsesquioxane of component (B), both cases are possible in which components (A) undergo a mutual curing reaction and components (B) undergo a mutual curing reaction independently of each other, and in which components (A) and (B) undergo a mutual curing reaction together, and the present invention includes all possible combinations.

In formula (2), (O _1/2 R ^a ) _r represents ^a Si ^-OH, Si- _O- alkyl group, or Si- _Ocycloalkyl group that remains after a portion of the condensation reaction is not completed when a polysilsesquioxane having a cage molecular structure composed of R 9 SiO 3/2 units and R 10 SiO 3/2 units is formed. That is, R ^a each independently represents a hydrogen atom, or an alkyl group having 1 to 20 carbon atoms, preferably 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms, particularly preferably a methyl group, an ethyl group, or an isopropyl group, or a cycloalkyl group having 5 to 20 carbon atoms, such as a cyclopentyl or cyclohexyl group.

When all of the condensation reactive groups in the polysilsesquioxane of formula (2) are bonded to each other to form Si-O-Si, r in formula (2) is 0 (zero). Such a case is called a complete cage structure. When r is not 0, all of the condensation reactive groups in the polysilsesquioxane of formula (2) are not bonded to each other to form Si-O-Si, and some of them are SiOR ^b . Such a case is called a partially cleaved structure. As described above, the cage molecular structure of polysilsesquioxane is known to be a complete cage structure and a partially cleaved structure, and either of these can be used as the polysilsesquioxane of formula (2) of the present invention. However, the polysilsesquioxane of formula (2) of the present invention is preferably a complete cage structure (i.e., r=0 in formula (2)) or a structure close thereto (for example, r is 20% or less, preferably 10% or less, relative to p+q), and it is particularly preferable that the polysilsesquioxane has a complete cage structure. Specific examples of the complete cage structure and partially cleaved structure of polysilsesquioxane are shown, for example, in paragraphs [0047] to [0049] of JP-A No. 2010-515778, and the cage polysilsesquioxane of the present invention may also have a similar chemical structure.

In formula (2), p and q may be any number as long as the polysilsesquioxane of formula (2) can have a cage molecular structure, and are not limited to any particular value. However, the total value of p and q in formula (2) is generally 6 to 20, preferably 8 to 20, more preferably 8 to 14, and particularly preferably 8, 10, or 12. Alternatively, the polysilsesquioxane of formula (2) may be a mixture of two or more polysilsesquioxanes having different totals of p and q. For example, the polysilsesquioxane of the present invention may be a mixture of polysilsesquioxanes having a cage molecular structure in which the total of p and q is 8, 10, or 12.

Furthermore, in the above formula (2), q may be 0 (zero). In that case, the polysilsesquioxane of component (B) does not have a curing reactive group bonded to a silicon atom. Therefore, when a composition using such component (B) is cured, under the curing conditions, a bond between the curing reactive groups of the polysilsesquioxane represented by formula (2) of component (B) and the curing reactive organo(poly)siloxane of component (A) is not formed in principle. However, even if such a bond is not formed, the compatibility of the organo(poly)siloxane of component (A) and the polysilsesquioxane represented by formula (2) is good, so that a highly uniform cured product can be obtained in which the polysilsesquioxane represented by formula (2) is uniformly dispersed without separation in the matrix formed by curing component (A). An embodiment in which q in formula (2) is 0 (zero) is one preferred embodiment of the curable composition of the present invention.

Therefore, in one preferred embodiment of the present invention, the polysilsesquioxane of formula (2) is represented by the following formula (2a), which corresponds to the case where q=0 in the above formula (2):
( ^R9SiO3 _/2 ) _p (O1 _/ ^2Ra ) _r (2a)
In formula (2a), R ⁹ is as defined for formula (2) above, and p is generally 6 to 20, preferably 8 to 20, more preferably 8 to 14, and particularly preferably 8, 10, or 12, or the compound of formula (2a) can be a mixture of any combination thereof. R ^a in formula (2a) is as defined for formula (2). In formula (2a), r is 0 or preferably 20% or less of p+r, more preferably 10% or less of p+r, and particularly preferably 5% or less of p+r. When the value of r is sufficiently small compared to p, the cage structure portion of the polysilsesquioxane of formula (2a) can have a clear void portion, which is considered to be effective in lowering the relative dielectric constant of the cured product obtained from the curable composition of the present invention.

As described above, the polysilsesquioxane of the above formula (2) may be a mixture of polysilsesquioxanes having different degrees of polymerization, in which the sum of p and q, or the value of p is different when q is 0, is different. In this case, the sum of p and q in formula (2), i.e., the number of silicon atoms, is 8 to 20 on average, the number average molecular weight of the polysilsesquioxane is in the range of 500 to 3,000, and the molecular weight dispersity ( _Mw / _Mn , where _Mw represents the weight average molecular weight and _Mn represents the number average molecular weight) is preferably 1.0 to 1.5, more preferably 1.0 to 1.4. The closer the value of _Mw / _Mn is to 1, the more advantageous it is for lowering the relative dielectric constant of the cured product obtained by curing the curable composition of the present invention. The weight average molecular weight and number average molecular weight of the polysilsesquioxane here are values measured by the weight average molecular weight and number average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC) method.

[ Component (C): Curing Agent ]
The curing agent of component (C) is a compound required for initiating or accelerating a curing reaction involving the curing reactive group of the organo(poly)siloxane of component (A), or in the case where component (B) has a curing reactive group, for initiating or accelerating a curing reaction involving the curing reactive groups of components (A) and (B) to cure the composition of the present invention, and it is preferable to use a compound appropriate for the type of reaction of the curing reactive group of the component (A) or components (A) and (B) used. Curing agents appropriate for the type of reaction of the curing reactive group are described below.

(1) When the curing reactive groups react via a hydrosilylation reaction When component (A) and/or component (B) as a whole contain groups capable of undergoing a hydrosilylation reaction as curing reactive groups, it is preferable to use a hydrosilylation reaction catalyst (C1) as a curing agent.
In such cases,
(i) When component (A) is made of one or more components selected from component (A1-1) and component (A1-2) having an alkenyl group, and component (A2) having a silicon-bonded hydrogen atom (Si—H),
(ii) In addition to the above (i), when component (B) has a group containing a carbon-carbon double bond as a curing reactive group, and/or when component (B) has a group having a silicon-bonded hydrogen atom (Si—H) or a Si—H group as a curing reactive group,
(iii) When component (A) has a group containing a carbon-carbon double bond as the curable reactive group, and component (B) has a Si-H group or a group having a Si-H group as the curable reactive group,
Among them, (i) and (ii) are preferred. In the case of (ii), a hydrosilylation reaction may occur between components (A) themselves, between components (B) themselves, and between components (A) and (B).

In the use of the present invention, the hydrosilylation reaction catalyst (C1) is
It is preferable for the composition to contain (C1-1) a first hydrosilylation reaction catalyst that exhibits catalytic activity in the composition without irradiation with high-energy rays such as ultraviolet rays, and/or (C1-2) a second hydrosilylation reaction catalyst that is inactive in the absence of irradiation with high-energy rays such as ultraviolet rays, but exhibits catalytic activity in the composition upon irradiation with high-energy rays, and the mass ratio of component (C1-1) to component (C1-2) is preferably in the range of 100/0 to 0/100.

Examples of high-energy rays include ultraviolet rays, X-rays, and electron beams, and among these, ultraviolet rays are preferred from the viewpoint of catalyst activation efficiency. The amount of irradiation varies depending on the type of high-energy ray-activated catalyst, but in the case of ultraviolet rays, the cumulative amount of irradiation at a wavelength of 365 nm is preferably within the range of 100 mJ/cm ² to 10 J/cm ² .

Component (C1-1) is a first hydrosilylation catalyst that exhibits catalytic activity in the curable composition of the present invention without irradiation with high-energy rays. This component is a hydrosilylation catalyst that gives the curable composition a desirable cure profile when the curable composition does not contain a hydrosilylation reaction inhibitor or contains a hydrosilylation reaction inhibitor in a small amount, and examples of the catalyst include platinum-based catalysts, rhodium-based catalysts, palladium-based catalysts, nickel-based catalysts, iridium-based catalysts, ruthenium-based catalysts, and iron-based catalysts, with platinum-based catalysts being preferred. Examples of platinum-based catalysts include platinum fine powder, platinum black, platinum-supported silica fine powder, platinum-supported activated carbon, chloroplatinic acid, alcohol solution of chloroplatinic acid, platinum olefin complexes, platinum alkenylsiloxane complexes, and other platinum compounds, with platinum alkenylsiloxane complexes being particularly preferred. Examples of this alkenylsiloxane include 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, alkenylsiloxanes in which a portion of the methyl groups of these alkenylsiloxanes have been substituted with ethyl groups, phenyl groups, etc., and alkenylsiloxanes in which the vinyl groups of these alkenylsiloxanes have been substituted with allyl groups, hexenyl groups, etc. In particular, 1,3-divinyl-1,1,3,3-tetramethyldisiloxane is preferred because the stability of the platinum-alkenylsiloxane complex containing it is good. In addition, since this can improve the stability of the platinum-alkenylsiloxane complex, it is preferable to add a compound selected from alkenylsiloxanes such as 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 1,3-diallyl-1,1,3,3-tetramethyldisiloxane, 1,3-divinyl-1,3-dimethyl-1,3-diphenyldisiloxane, 1,3-divinyl-1,1,3,3-tetraphenyldisiloxane, and 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, and organosiloxane oligomers such as dimethylsiloxane oligomers to the complex, and it is particularly preferable to add an alkenylsiloxane to the platinum complex.

Component (C1-1) is a catalyst that shows activity without irradiation with high-energy rays, but among them, those that show activity even at relatively low temperatures are preferable. Specifically, it shows catalytic activity in the composition in the temperature range of 0 to 200°C and promotes the hydrosilylation reaction. The content of component (C1-1) varies depending on the type of catalyst and the type of composition, but is usually an amount in which the metal atoms in this catalyst are within the range of 0.01 to 50 ppm by mass relative to the composition. In particular, it is particularly preferable to use a platinum alkenylsiloxane complex (C1-1-1) so that the platinum content of the curable composition is preferably within the range of 1.5 to 30 ppm, since this can achieve a good curing speed. If the amount of component (C1-1) added is too small, the curing of the composition will be slow, and if the amount of component (C1-1) added is too large, the pot life will be too short, causing practical inconvenience and being uneconomical. By adjusting the amount of catalyst added, the curing speed of the curable composition can be adjusted to the desired speed.

Component (C1-2) is a second hydrosilylation catalyst that does not exhibit catalytic activity without exposure to high-energy rays, but exhibits catalytic activity in the curable composition of the present invention upon exposure to high-energy rays such as ultraviolet rays, and is known as a high-energy ray-activated catalyst or photoactivated catalyst.

Specific examples of component (C1-2) include (methylcyclopentadienyl)trimethylplatinum(IV), (cyclopentadienyl)trimethylplatinum(IV), (1,2,3,4,5-pentamethylcyclopentadienyl)trimethylplatinum(IV), (cyclopentadienyl)dimethylethylplatinum(IV), (cyclopentadienyl)dimethylacetylplatinum(IV), (trimethylsilylcyclopentadienyl)trimethylplatinum(IV), (methoxycarbonylcyclopentadienyl)trimethylplatinum(IV), (dimethylphenylsilylcyclopentadienyl)trimethylcyclopentadienylplatinum(IV), (1,5-cyclooctadiene)dimethylplatinum(II), (1,5-cyclooctadiene)diphenyl ...IV), (1,5-cyclooctadiene)diphenylplatinum(IV), (1,5-cyclooctadiene)diphenylplatinum(IV), (1,5-cyclooctadiene)diphenylplatinum(IV), (1,5-cyclooctadiene)diphenylplatinum(IV), (1,5-cyclooctadiene)diphenylplatinum(IV), (1,5-cyclooctadiene)diphenylplatinum(IV), (1,5-cyclo (2,5-norbornadiene)dichloroplatinum(II), (2,5-norbornadiene)dimethylplatinum(II), (2,5-norbornadiene)dichloroplatinum(II), trimethyl(acetylacetonato)platinum(IV), trimethyl(3,5-heptanedionato)platinum(IV), trimethyl(methylacetoacetate)platinum(IV), bis(2,4-pentanedionato)platinum(II), bis(2,4-hexanedionato)platinum(II), bis(2,4-heptanedionato)platinum(II), bis(3,5-heptanedionato)platinum(II), bis(1-phenyl-1,3-butanedionato)platinum(II), bis(1,3-diphenyl-1,3-propanedionato)platinum(II), and bis(hexafluoroacetylacetonato)platinum(II). Among these, (methylcyclopentadienyl)trimethylplatinum(IV) and bis(2,4-pentanedionato)platinum(II) are preferred due to their versatility and ease of availability.

When component (C1-2) is used alone, its catalytic activity can be controlled by the cumulative amount of high-energy irradiation, and it is advantageous in terms of adjusting the pot life. On the other hand, when component (C1-2) is used in combination with component (C1-1), the reaction product obtained by (C1-1) can be given secondary curing properties (hereinafter sometimes referred to as "photocuring properties") by irradiation with high-energy rays, and by simultaneously irradiating high-energy rays in the presence of component (C1-1), the curing reaction can proceed auxiliaryally even in areas where sufficient light irradiation cannot be performed, and further curing reaction can be progressed for non-fluid reaction products, and further rapid curing/drying properties can be achieved compared to (C1-1) alone. When component (C1-2) is used, its amount is sufficient to increase the curing rate of the curable composition to a desired level, and is preferably an amount in which the metal atoms in this catalyst are within the range of 1 to 50 ppm by mass, and preferably within the range of 5 to 50 ppm, relative to the curable composition.

When the curable composition of the present invention contains a hydrosilylation catalyst that is a catalyst activated by high-energy rays such as ultraviolet rays or a photoactivated catalyst, which is component (C1-2), it can be designed to further have the characteristic of forming a non-flowable reactant within at least 20 minutes at 25°C when irradiated with high-energy rays immediately after preparation of the composition. The timing and amount of irradiation of high-energy rays such as ultraviolet rays in the composition of the present invention are optional, and when using the curable composition, the curable composition may be irradiated with high-energy rays immediately after application to a substrate or the like, or may be irradiated with high-energy rays as an auxiliary after a certain period of time. In addition, although the practical irradiation amount and the irradiation amount for defining the above-mentioned characteristics are as described above, it is sufficient to adopt an appropriate irradiation amount in actual use, and the irradiation amount is not limited to the above-mentioned irradiation amount.

When the curable composition of the present invention is one that cures by a hydrosilylation reaction, it may or may not contain a hydrosilylation reaction inhibitor together with the above-mentioned hydrosilylation catalyst. A hydrosilylation reaction inhibitor is usually added to a curable composition in order to improve the pot life of the composition and obtain a stable composition, but in the curable composition of the present invention, a hydrosilylation reaction inhibitor may not be added in order to prevent the curing time of the curable composition from being delayed. However, a hydrosilylation reaction inhibitor may be added to the composition in order to extend the pot life of the curable composition. Hydrosilylation reaction inhibitors are known in the art, and specific examples include alkyne alcohols such as 1-ethynylcyclohexan-1-ol, 2-methyl-3-butyn-2-ol, 3,5-dimethyl-1-hexyn-3-ol, and 2-phenyl-3-butyn-2-ol; enyne compounds such as 3-methyl-3-penten-1-yne and 3,5-dimethyl-3-hexen-1-yne; methylalkenylsiloxane oligomers such as 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane and 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane; alkyneoxysilanes such as dimethylbis(1,1-dimethyl-2-propynoxy)silane and methylvinylbis(1,1-dimethyl-2-propynoxy)silane, and triallyl isocyanurate compounds.
The content of this hydrosilylation reaction inhibitor in the curable composition is not particularly limited, and is preferably within the range of 0.0001 to 5 parts by mass, 0.01 to 5 parts by mass, or 0.01 to 3 parts by mass, per 100 parts by mass of the total of components (A) to (C). However, when the composition of the present invention is cured or semi-cured by leaving it at room temperature without heating and/or irradiating with high-energy rays, it does not need to contain a hydrosilylation reaction inhibitor, and from the viewpoint of the curing reaction, it is preferable that the composition does not contain a hydrosilylation reaction inhibitor.

(2) When component (A) is cured by a condensation reaction of a hydrolyzable silyl group and/or a silicon-bonded hydroxyl group In the curable composition of the present invention, when the curing reactive group possessed by component (A) is a hydrolyzable silyl group and/or a silicon-bonded hydroxyl group and the composition is cured by a condensation reaction of the hydrolyzable silyl group and/or the silicon-bonded hydroxyl group, a hydrolysis and condensation reaction catalyst (C2) for the hydrolyzable silyl group can be used as a curing agent for component (C). Such condensation reaction catalysts are known in the art, and any one or more can be selected and used. Examples of the condensation reaction catalyst include organotin compounds such as dibutyltin dilaurate, dibutyltin diacetate, tin octenate, dibutyltin dioctate, and tin laurate; organotitanium compounds such as tetrabutyl titanate, tetrapropyl titanate, and dibutoxybis(ethylacetoacetate); acidic compounds such as hydrochloric acid, sulfuric acid, and dodecylbenzenesulfonic acid; alkaline compounds such as ammonia and sodium hydroxide; and amine compounds such as 1,8-diazabicyclo[5.4.0]undecene (DBU) and 1,4-diazabicyclo[2.2.2]octane (DABCO). It is preferable to use a compound selected from the group consisting of organotin compounds and organotitanium compounds as component (C).

The amount of condensation reaction catalyst (C2) used is preferably an amount that will give a desired curing profile when the curable composition is cured.

(3) When component (A) is cured by radical polymerization reaction When the curable composition of the present invention has a curing reactive group that is a radical polymerizable group and the composition is cured by radical polymerization reaction, a radical polymerization initiator can be used as the curing agent of component (C). As the radical polymerization initiator, an initiator of the type that generates free radicals by heat, known as a thermal radical polymerization initiator, and/or an initiator of the type that generates free radicals by light irradiation, known as a photoradical polymerization initiator, can be used.

Examples of thermal radical polymerization initiators include, but are not limited to, azo compounds and peroxides such as 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile, 2,2'-azobis(2-methylbutyronitrile), 4,4'-azobis(4-cyanopentanoic acid, 2,2'-azobis(2-methylpropionamidine) dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride, perbenzoic acid, tert-butyl hydroperoxide, cumene hydroperoxide, di-tert-butyl peroxide, dimethyl 2,2'-azobis(2-methylpropionate), and dicumyl peroxide.

Photoradical polymerization initiators and sensitizers will be described later.

(4) When component (A) is cured by a peroxide crosslinking reaction In the curable composition of the present invention, when the curing reactive group of component (A) is a group that can be crosslinked by a peroxide, particularly an organic peroxide, and the composition is cured by the crosslinking reaction, it is preferable to use an organic peroxide, particularly an acyl-based organic peroxide and an alkyl-based organic peroxide, as the curing agent of component (C). Examples of organic peroxides include dibenzoyl peroxide, 4,4'-dimethyldibenzoyl peroxide, 3,3'-dimethyldibenzoyl peroxide, 2,2'-dimethyldibenzoyl peroxide, 2,2',4,4'-tetrachlorodibenzoyl peroxide, and cumyl peroxide.

(5) When component (A) contains an organo(poly)siloxane having an ultraviolet-curable functional group In the curable composition of the present invention, when component (A) contains an organo(poly)siloxane having an ultraviolet-curable functional group as a curing reactive group, when the curing reactive group of component (A) is a photocationically polymerizable functional group, it is preferable to use a photocationically polymerizable initiator as the curing agent of component (C). When the curing reactive group of component (A) is a photoradical polymerizable group, it is preferable to use a photoradical polymerization initiator as the curing agent of component (C). Furthermore, these photopolymerization initiators can be used in combination with a sensitizer if desired. When the ultraviolet-curable functional group is crosslinked by electron beam irradiation, a photopolymerization initiator is usually not required.

(5-1) Photocationic Polymerization Initiator The photocationic polymerization initiator used in the composition of the present invention can be arbitrarily selected from those known in the art, and is not particularly limited to a specific one. As the photocationic polymerization initiator, strong acid generating compounds such as diazonium salts, sulfonium salts, iodonium salts, and phosphonium salts are known, and these can be used. Examples of photocationic polymerization initiators include bis(4-tert-butylphenyl)iodonium hexafluorophosphate, cyclopropyldiphenylsulfonium tetrafluoroborate, dimethylphenacylsulfonium tetrafluoroborate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroarsenate, diphenyliodonium tetrafluoromethanesulfonate, 2-(3,4-dimethoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-[2-(furan-2-yl)vinyl]-4,6-bis(trichloromethyl)-1,3,5-triazine, and 4-isopropyl-4'-methyldiphenyliodonium. Tetrakis(pentafluorophenyl)borate, 2-[2-(5-methylfuran-2-yl)vinyl]-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-(4-methoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine, 4-nitrobenzenediazonium tetrafluoroborate, triphenylsulfonium tetrafluoroborate, triphenylsulfonium bromide, tri-p-tolylsulfonium hexafluorophosphate, tri-p-tolylsulfonium trifluoromethanesulfonate, diphenyliodonium triflate, triphenylsulfonium triflate, diphenyliodonium nitrate, bis(4-tert-butylphenyl)iodonium perfluoro-1-butanesulfonate, bis(4-tert-butylphenyl)iodonium Examples of the photocationic polymerization initiator include, but are not limited to, triflate, triphenylsulfonium perfluoro-1-butanesulfonate, N-hydroxynaphthalimide triflate, p-toluenesulfonate, diphenyliodonium p-toluenesulfonate, (4-tert-butylphenyl)diphenylsulfonium triflate, tris(4-tert-butylphenyl)sulfonium triflate, N-hydroxy-5-norbornene-2,3-dicarboximide perfluoro-1-butanesulfonate, (4-phenylthiophenyl)diphenylsulfonium triflate, and 4-(phenylthio)phenyldiphenylsulfonium triethyltrifluorophosphate. In addition to the above compounds, examples of the photocationic polymerization initiator include commercially available photoinitiators such as Omnicat 250, Omnicat 270 (both from IGM Resins BV) and Irgacure 290 (from BASF).

The amount of photocationic polymerization initiator added to the composition of the present invention is not particularly limited as long as the desired photocuring reaction occurs, but it is generally used in the range of 0.1 to 50 parts by mass, preferably 0.5 to 20 parts by mass, based on 100 parts by mass of the total amount of photocationic polymerizable functional groups in the composition of the present invention. Alternatively, it is preferable to use the photocationic polymerization initiator in an amount of 0.1 to 3% by mass, particularly 0.2 to 1% by mass, based on the total amount of components (A) and (B) of the present invention.

(5-2) Photoradical polymerization initiator Known photoradical polymerization initiators are roughly divided into photocleavage type and hydrogen abstraction type. The photoradical polymerization initiator used in the composition of the present invention can be arbitrarily selected from those known in the art and is not particularly limited to a specific one. Examples of photoradical polymerization initiators include acetophenone, p-anisyl, benzil, benzoin, benzophenone, 2-benzoylbenzoic acid, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(dimethylamino)benzophenone, benzoin methyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin ethyl ether, 4-benzoylbenzoic acid, 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, methyl 2-benzoylbenzoate, 2-(1,3-benzodioxol-5-yl)-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-benzyl-2-(dimethylamino)- 4'-Morpholinobutyrophenone, (±)-Camphorquinone, 2-Chlorothioxanthone, 4,4'-Dichlorobenzophenone, 2,2-Diethoxyacetophenone, 2,2-Dimethoxy-2-phenylacetophenone, 2,4-Diethylthioxanthen-9-one, Diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, Ethyl(2,4,6-trimethylbenzoyl)phenylphosphinate, 1,4-Dibenzoylbenzene, 2-Ethylanthraquinone, 1-Hydroxycyclohexyl phenyl ketone, 2-Hydroxy-2-methylpropiophenone, 2-Hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, 2-Isopropylthioxanthone, Lithium These include, but are not limited to, phenyl(2,4,6-trimethylbenzoyl)phosphineate, 2-methyl-4'-(methylthio)-2-morpholinopropiophenone, 2-isonitrosopropiophenone, 2-phenyl-2-(p-toluenesulfonyloxy)acetophenone, and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide. In addition to the above-mentioned compounds, examples of the photoradical polymerization initiator include Omnirad 651, 184, 1173, 2959, 127, 907, 369, 369E, and 379EG (alkylphenone-based photopolymerization initiators, IGM Resins BV), Omnirad TPO H, TPO-L, and 819 (acylphosphine oxide-based photopolymerization initiators, IGM Resins BV), Omnirad MBF and 754 (intramolecular hydrogen abstraction type photopolymerization initiators, IGM Resins BV), and Irgacure OXE01 and OXE02 (oxime ester-based non-depolymerization initiators, BASF).

The amount of photoradical polymerization initiator added to the composition of the present invention is not particularly limited as long as the desired photopolymerization reaction or photocuring reaction occurs, but it is generally used in an amount of 0.01 to 5 mass %, preferably 0.05 to 1 mass %, based on the total mass of the composition of the present invention.

A photosensitizer can also be used in combination with the above-mentioned photocationic polymerization initiator or photoradical polymerization initiator. The use of a sensitizer can increase the photon efficiency of the polymerization reaction, and since light of a longer wavelength can be used for the polymerization reaction compared to the case where only a photoinitiator is used, it is known to be particularly effective when the coating thickness of the composition is relatively thick or when an LED light source with a relatively long wavelength is used. As sensitizers, anthracene-based compounds, phenothiazine-based compounds, perylene-based compounds, cyanine-based compounds, merocyanine-based compounds, coumarin-based compounds, benzylidene ketone-based compounds, (thio)xanthene or (thio)xanthone-based compounds, such as isopropylthioxanthone, 2,4-diethylthioxanthone, squarium-based compounds, (thia)pyrylium-based compounds, and porphyrin-based compounds, are known, and any photosensitizer can be used in the curable composition of the present invention, without being limited to these.

The above-mentioned curing agent (C) can be used in combination of one or more curing agents corresponding to the type of curing reactive group possessed by component (A) depending on the type of the curing reactive group. For example, when component (A) contains both a functional group capable of crosslinking by a hydrosilylation reaction and a reactive group capable of crosslinking by a condensation reaction as a curing reactive group, a hydrosilylation catalyst and a condensation catalyst can be used in combination as a curing agent. Also, when component (A) contains a functional group capable of crosslinking by a hydrosilylation reaction and a cationic polymerizable group that is a UV-curable group as a curing reactive group, a combination of a hydrosilylation catalyst and a photocationic polymerization initiator can be used as a curing agent. In this way, depending on the curing group or curing reactive functional group possessed by component (A), a curing agent that is effective for crosslinking them to cure the composition can be used alone or in combination of two or more curing agents.

The above points are the same when polysilsesquioxane having a curing reactive group is used as component (B), and a curing agent capable of promoting the curing reaction involving the curing reactive group of component (B) can be used. In this case, if the reaction of the curing reactive group of component (B) is the same type of reaction as the reaction of the curing reactive group of component (A), the curing agent (C) for the reaction of the curing reactive group of component (A) can function as a curing agent (C) for the curing reactive group of component (B) as it is. On the other hand, if the reaction of the curing reactive group of component (B) is a different type of reaction from the reaction of the curing reactive group of component (A), and the curing agent (C) for component (A) is not effective as a curing agent (C) for the curing reactive group of component (B), a curing agent for component (B) can be used in addition to the curing agent for component (A).

[Curing reaction of component (A), or a combination of components (A) and (B)]
In the curable composition of the present invention, the curable reactive group may be roughly divided into two cases: only component (A) has a curable reactive group, and both component (A) and component (B) have a curable reactive group. Furthermore, the type of curable reactive group possessed by each component may be one or more types. Furthermore, the curable reactive group possessed by component (A) or components (A) and (B) may be a curable reactive group involved in one type of reaction, or a combination of different functional groups that may be involved in two or more types of reactions. Therefore, the type of curing reaction in which the curable reactive group possessed by component (A) participates and the type of curing reaction in which the curable reactive group that component (B) may have participates may be an arbitrary combination of one or more types of curing reactions from those described above. Specifically, it is preferable to combine one or more types of the following reactions as the curing reaction in which component (A) and component (B) participate.
(i) hydrosilylation reactions; (ii) condensation reactions of hydrolyzable silyl groups and/or silicon-bonded hydroxyl groups; (iii) radical polymerization reactions; and (iv) peroxide crosslinking reactions.
Furthermore, the combination of one or two of the above curing reactions may be used.
(v) A curing reactive group that participates in an ultraviolet curing reaction can be further combined.
In addition, the curing reaction between components (A) and the curing reaction between components (A) and (B) may be treated as different types of curing reactions, and the molecules may be designed so that components (A) and (B) each undergo a curing reaction independently.

Therefore, the curing reaction involving the curing reactive group possessed by component (A) or components (A) and (B) of the curable composition of the present invention may be, for example, any one of the above (i) to (iv), or a combination of two of each of the curing reactions (i) and (ii), (i) and (iii), (i) and (iv), (ii) and (iii), (ii) and (iv), and (iii) and (iv), or any combination of three or four types of curing reactions. Furthermore, each of these curing reactions or combinations thereof may be further combined with an ultraviolet curing reaction (v).

That is, the curable composition according to one embodiment of the present invention further contains, as component (A), an organo(poly)siloxane having one or more curing reactive groups involved in one or more of the above-mentioned curing reactions (i) to (iv), and an organo(poly)siloxane having an ultraviolet-curable functional group, and can be cured by a crosslinking reaction caused by energy beam irradiation in addition to a hydrosilylation reaction, a condensation reaction of a hydrolyzable silyl group and/or a silicon-bonded hydroxyl group, a radical polymerization reaction, and/or a peroxide crosslinking reaction of the organo(poly)siloxane. Among the embodiments in which one or more of the curing reactions (i) to (iv) are combined with a crosslinking reaction caused by energy beam irradiation, it is particularly preferable to combine the hydrosilylation reaction (i) with a crosslinking reaction caused by energy beam irradiation.

In general, when component (B) has a curing reactive group, it is preferable to select each curing reactive group so that the curing reactive group of component (A) and the curing reactive group of component (B) are involved in the same curing reaction so that a curing reaction, for example a crosslinking reaction, can occur between the curing reactive group of component (A) and the curing reactive group of component (B). This makes it possible to obtain a cured product in which components (A) and (B) are chemically bonded. Specifically, when a hydrosilylation reaction is used as the curing reaction, component (A) includes an organohydrogen(poly)siloxane having a silicon-bonded hydrogen atom (Si-H) and an organo(poly)siloxane having a curing reactive group having a carbon-carbon double bond, and component (B) can be used that has a carbon-carbon double bond or Si-H, especially a carbon-carbon double bond, as the curing reactive group, which is a particularly preferred embodiment of the present invention. In addition, when the curing reactive group of component (A) is a group that participates in the condensation reaction of a hydrolyzable silyl group and/or a silicon-bonded hydroxyl group, by using a polysilsesquioxane having a cage molecular structure that has a group that participates in the condensation reaction of a hydrolyzable silyl group and/or a silicon-bonded hydroxyl group as component (B), components (A) and (B) can be chemically bonded together.

The curable composition of the present invention also includes an embodiment in which component (A) alone cannot form a cured product through a curing reaction involving the curing reactive group of component (A), but the curable composition is cured to form a cured product through a total curing reaction between component (A) and component (B) having a curing reactive group. In other words, when component (A) alone does not form a cured product that is a crosslinking reaction product, it is necessary for the entire composition to form a cured product through a curing reaction between component (B) and component (A).

In the composition of the present invention, it is preferable to use one or more curing agents for the reaction in combination depending on the curing reaction involving component (A) or components (A) and (B). That is, when the curing reaction involving component (A) is a hydrosilylation reaction, or when component (B) has a curing reactive group, when component (A) and component (B) are involved, it is preferable that the curing agent contains a hydrosilylation reaction catalyst. When the curing reaction involving component (A) is a condensation reaction of hydrolyzable silyl groups and/or silicon-bonded hydroxyl groups, or when component (B) has a curing reactive group, when component (A) and component (B) are involved, it is preferable that the curing agent contains a condensation reaction catalyst. When the curing reaction involving component (A) is a radical reaction, or when component (B) has a curing reactive group, when component (A) and component (B) are involved, it is preferable that the curing agent contains a radical initiator. When the curing reaction involving component (A) or the curing reaction involving components (A) and (B) when component (B) has a curing reactive group is a peroxide crosslinking reaction of organo(poly)siloxane, it is preferable that the curing agent contains an organic peroxide. Also, when the curing reaction involving component (A) or the curing reaction involving components (A) and (B) when component (B) has a curing reactive group is an ultraviolet curing reaction, it is preferable that the curing agent contains a photoinitiator. As described above, two or more types of curing reactions can be used in combination in one curable composition, so in that case, it is preferable to use two or more types of curing agents required depending on the curing reaction in combination.

Particularly preferred combinations of components (A) and (B) for the curable composition of the present invention are as follows.
(i) The curing reaction in which component (A) participates is a hydrosilylation reaction, component (A) contains the above-mentioned component (A1), preferably the above-mentioned component (A1-1) and/or component (A1-2), and component (A2), preferably the above-mentioned component (A2-1) or a combination of components (A2-1) and (A2-2), and component (B) does not have a curing reactive group.
(ii) The curing reaction involving components (A) and (B) is a hydrosilylation reaction, component (A) contains the above-mentioned component (A1), preferably the above-mentioned component (A1-1) and/or component (A1-2), and component (A2), preferably the above-mentioned component (A2-1) or a combination of components (A2-1) and (A2-2), and component (B) contains a curing reactive group having a carbon-carbon double bond capable of participating in a hydrosilylation reaction.
(iii) The curing reaction involving components (A) and (B) is a hydrosilylation reaction, component (A) contains the above-mentioned component (A1), preferably the above-mentioned component (A1-1) and/or component (A1-2), and component (A2), preferably the above-mentioned component (A2-1) or a combination of components (A2-1) and (A2-2), and component (B) contains a silicon-bonded hydrogen atom (Si—H) or a curing reactive group containing Si—H.
(iv) In addition to any one of the above (i) to (iii), the composition further contains, as component (A), an organo(poly)siloxane having an ultraviolet-curable functional group.

As the curable composition according to the above aspects (ii) and (iii), there can be mentioned a curable composition in which component (B) has a curing reactive group, the curing reaction involving components (A) and (B) is a hydrosilylation reaction, component (A) is an organo(poly)siloxane having an alkenyl group-containing group, or an organo(poly)siloxane having a SiH group, or a combination thereof, component (B) is a polysilsesquioxane having a cage-like molecular structure having an SiH group, or a polysilsesquioxane having a cage-like molecular structure having an alkenyl group, the curing reactive groups of components (A) and (B) are selected so that components (A) and (B) can crosslink, and components (A) and (B) can crosslink by a hydrosilylation reaction, and the curing agent includes a hydrosilylation reaction catalyst.

The curable composition of the present invention can be cured at room temperature (particularly room temperature, e.g., 5 to 30°C) or under heated conditions (e.g., higher than 30°C and not higher than 200°C) due to the effect of the curing agent described above. In this case, it is not necessary to irradiate the curable composition with energy rays from the outside to promote the curing reaction, but if component (A) and/or component (B) contain a component having an ultraviolet-curable functional group, energy rays may be irradiated.

[Ratio of Components (A) and (B), Amount of Component (C), and Viscosity of Composition]
As described above, component (A) and component (B) having a curing reactive group have a curing reactive group selected so that a curing reaction can occur by one reaction or a combination of two or more reactions selected from hydrosilylation reaction, condensation reaction of hydrolyzable silyl group and/or silicon-bonded hydroxyl group, and peroxide crosslinking reaction of organo(poly)siloxane, and component (A) may be one organo(poly)siloxane or a combination of two or more organo(poly)siloxanes, i.e., a mixture, and component (B) may also be one or a mixture of two or more silsesquioxanes. In addition to the above curing system, ultraviolet-curable functional groups may be used as the curing reactive groups of component (A) or component (B). The amount of component (A) contained in the curable composition of the present invention is 40% by mass or more of the total composition, and particularly preferably 50% by mass or more. The ratio of component (A) to component (B) in the composition is, in mass ratio, (1-99):(99-1), preferably (25-99):(75-1), more preferably (50-99):(50-1). That is, the proportion of component (A) in the total of components (A) and (B) in the composition of the present invention is 1 mass% or more, preferably 25 mass% or more, more preferably 50 mass% or more. The amount of component (B) is not particularly limited as long as the composition of the present invention exhibits the desired properties, but is generally 60 mass% or less, preferably 50 mass% or less, and 7% or more, preferably 10 mass% or more, more preferably 15 mass% or more of the entire composition.

The cured product obtained from the composition of the present invention can be designed to have the desired hardness, tear strength, tensile strength, viscoelasticity including elongation at break, adhesive strength, curing reaction speed, etc., by selecting the structure, chain length, crosslinking density, and crosslinking reaction site of the organo(poly)siloxane component having a curing reactive group. For example, it is possible to design the molecule so that the physical properties according to the application of the cured product are obtained by selecting a polymer with molecular chain end reactivity, selecting a polymer with molecular chain side chain reactivity, selecting a resinous or branched polymer, etc., and any such cured product is included in the scope of the present invention. Furthermore, the shape of the cured product obtained from the curable composition of the present invention is not particularly limited, and may be a thin film coating layer or a molded product such as a sheet. The composition of the present invention may also be injected into a specific part of an article in an uncured state and then cured to form a filling, and the composition of the present invention may be used as a sealant or intermediate layer for a laminate or a display device, etc.

The cured product obtained from the composition of the present invention is substantially transparent and can be used for bonding or fixing between members, and can therefore be used as an optically transparent adhesive (OCA) or optically transparent resin (OCR). Furthermore, the composition of the present invention can form not only a resinous cured product with high hardness, but also a soft elastomeric cured product or a gel-like cured product, and therefore may be used in optical components, electronic components, protective materials for electronic materials, functional elastomers, functional gels, etc., which require a low relative dielectric constant. In addition, the cured product may be given further functions by using additives, etc., which will be described later.

The cured product obtained from the composition of the present invention is characterized by a low dielectric constant, and therefore the composition of the present invention is suitable for use as a coating agent or potting agent, particularly as an insulating coating agent or potting agent for electronic and electrical devices.

When the composition of the present invention is used as a coating agent, in order to provide the composition with suitable fluidity and workability for application to a substrate, the viscosity of the entire composition is preferably 1 to 5000 mPa·s, more preferably 5 to 1000 mPa·s, and particularly preferably 5 to 500 mPa·s at 25°C. In order to adjust the viscosity of the entire composition to a desired viscosity, it is preferable to use an organo(poly)siloxane as component (A) having a viscosity that will give the entire composition the desired viscosity. To achieve this, the molecular weight of the organo(poly)siloxane of component (A) can be appropriately adjusted to appropriately adjust the viscosity.

In order to adjust the viscosity of the composition of the present invention, an organic solvent can be used as a diluent. The organic solvent is not limited to a specific organic solvent as long as it can dissolve the above-mentioned components (A) and (B) to form a uniform solution. Examples of organic solvents that can be used include ester solvents, ether solvents, ketone solvents, and hydrocarbon solvents, which have a boiling point of 200°C or less at normal pressure. In particular, those with a boiling point of 60°C or more and 200°C or less are preferable. Specific organic solvents include ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 2-methoxyethyl acetate, 2-ethoxyethyl acetate, 2-propyloxyethyl acetate, 2-butoxyethyl acetate, propylene glycol-1-monomethyl ether-2-acetate, 1,2-dimethoxyethane, 2-methoxyethanol, 1,2-diethoxyethane, 2-ethoxyethanol, diethylene glycol dimethyl ether, diethylene glycol diethyl ... Examples of the solvent include ethylene glycol ethyl methyl ether, diethylene glycol monomethyl ether, dibutyl ether, tetrahydrofuran, 1,4-dioxane, anisole, phenetole, 2-butanone, 2-pentanone, 3-pentanone, methyl isobutyl ketone, isoamyl methyl ketone, hexane, heptane, n-octane, 2,2,4-trimethylpentane, cyclohexane, methylcyclohexane, ethylcyclohexane, toluene, xylene, mesitylene, ethylbenzene, and a mixture of two or more selected from these. However, the curable organo(poly)siloxane composition of the present invention does not contain any organic solvent at all, or even if it contains an organic solvent, the amount is preferably 10% or less of the entire composition, further 5% or less, and particularly 1% or less. It is particularly preferable that the composition of the present invention contains an organic solvent, but the amount is 1% or less of the entire composition, or does not contain any organic solvent at all. As described above, the composition of the present invention can achieve a viscosity that allows the entire composition to be easily applied to a substrate as a coating agent without using an organic solvent by adjusting the viscosity of component (A).

If necessary, from the viewpoint of adjusting the viscosity of the curable composition of the present invention and improving the coatability of the composition, it is possible and preferable to add a non-volatile or low-volatile low-molecular-weight compound having a boiling point of more than 200°C at normal pressure. Such a low-molecular-weight compound has a molecular weight of 500 or less and is non-volatile or low-volatile, is different from the above organic solvent, has a boiling point of more than 200°C, and preferably has a symmetrical molecular structure so as to maintain low dielectric properties, but is not limited thereto. In addition, this low-molecular-weight compound may be a compound having a curable functional group, and may be, for example, a reactive diluent having a functional group capable of reacting with the curable reactive group of the above component (A). Specific examples of non-volatile or low-volatile low-molecular-weight compounds include dodecane, tetradecane, hexadecane, dodecene, tetradecene, and hexadecene, with tetradecane and tetradecene being preferred. The amount of the compound is the amount necessary to adjust the viscosity of the curable composition, and may be 10% or less of the entire composition, or even 5% or less.

〔Additive〕
In addition to the above-mentioned components, the curable composition of the present invention may contain additives for improving the properties of the curable composition or the cured product obtained therefrom.

Adhesion promoters are preferably added to the curable composition of the present invention in order to improve the adhesion or adhesion between the cured product obtained from the curable composition or the curable composition in the middle of curing and the substrate with which it is in contact. As the adhesion promoter, any known adhesion promoter that can be added to a curable silicone composition can be used. When the curable composition of the present invention is cured by utilizing a hydrosilylation reaction, it is preferable to use a known adhesion promoter that can be added to a curable silicone composition that is cured by a hydrosilylation reaction.

Such adhesion promoters include organosilanes having a trialkoxysiloxy group (e.g., trimethoxysiloxy group, triethoxysiloxy group) or a trialkoxysilylalkyl group (e.g., trimethoxysilylethyl group, triethoxysilylethyl group) and a hydrosilyl group or an alkenyl group (e.g., vinyl group, allyl group), or organosiloxane oligomers having a linear, branched or cyclic structure with about 4 to 20 silicon atoms; organosilanes having a trialkoxysiloxy group or a trialkoxysilylalkyl group and a methacryloxyalkyl group (e.g., 3-methacryloxypropyl group); ganosilane, or an organosiloxane oligomer having a linear, branched or cyclic structure with about 4 to 20 silicon atoms; an organosilane having a trialkoxysiloxy group or a trialkoxysilylalkyl group and an epoxy group-bonded alkyl group (e.g., 3-glycidoxypropyl group, 4-glycidoxybutyl group, 2-(3,4-epoxycyclohexyl)ethyl group, 3-(3,4-epoxycyclohexyl)propyl group), or an organosiloxane oligomer having a linear, branched or cyclic structure with about 4 to 20 silicon atoms; a trialkoxysilyl group (e.g., trimethoxysilyl group, triethoxysilyl group, organic compounds having two or more alkyl groups); a reaction product of an aminoalkyltrialkoxysilane with an epoxy group-bonded alkyltrialkoxysilane, and an epoxy group-containing ethyl polysilicate. Specific examples of such compounds include vinyltrimethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, hydrogentriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 1,6-bis(2-methylphenyl)ethyltrimethoxy ...2-(2-methylphenyl)ethyltrimethoxysilane, 2-(2-methylphenyl)ethyltrimethoxysilane, 2-(2-methylphenyl)ethyltrimethoxysilane, 2-(2-methylphenyl)ethyltrimethoxysilane, 2-(2-methylphenyl)ethyltrimethoxysilane, 2-(2-methylphenyl)ethyltrimethoxysilane, 2-(2-methylphenyl)ethyltrimethoxysilane, (trimethoxysilyl)hexane, 1,6-bis(triethoxysilyl)hexane, 1,3-bis[2-(trimethoxysilyl)ethyl]-1,1,3,3-tetramethyldisiloxane, a reaction product of 3-glycidoxypropyltriethoxysilane and 3-aminopropyltriethoxysilane, a condensation reaction product of a silanol group-blocked methylvinylsiloxane oligomer and 3-glycidoxypropyltrimethoxysilane, a condensation reaction product of a silanol group-blocked methylvinylsiloxane oligomer and 3-methacryloxypropyltriethoxysilane, and tris(3-trimethoxysilylpropyl)isocyanurate.

The content of such adhesion promoters in the curable composition is not particularly limited, but it is preferably within the range of 0.01 to 10 parts by mass, or 0.01 to 5 parts by mass, per 100 parts by mass of the total of components (A) and (B), in order to ensure that the curing characteristics of the composition are within a desirable range and to avoid promoting discoloration of the cured product.

Other additives In addition to the above-mentioned components, other additives may be added to the curable composition of the present invention as desired. Additives that can be used include organopolysiloxanes other than components (A) and (B); leveling agents; ultraviolet absorbers; antioxidants; polymerization inhibitors; fillers (functional fillers such as reinforcing fillers, insulating fillers, and thermally conductive fillers), such as inorganic fillers such as silica, glass, alumina, and zinc oxide, organic resin fine powders such as polymethacrylate resins, phosphors; heat resistance agents; dyes; pigments; flame retardant agents; and solvents, but are not limited thereto. If necessary, appropriate additives can be added to the composition of the present invention. In addition, if necessary, a thixotropic agent may be added to the composition of the present invention, especially when used as a potting agent or a sealing material.

[Dielectric constant of the cured product of the composition of the present invention]
The cured product obtained from the curable composition of the present invention can have a low dielectric constant, and the relative dielectric constant, measured at 23° C., can be less than 2.8, preferably less than 2.7.

[Application]
The composition of the present invention can be used as an insulating material by utilizing the property that the relative dielectric constant of the cured product obtained therefrom is low. Specifically, the composition of the present invention is particularly useful as a material for forming an insulating layer constituting various articles, particularly electronic devices and electric devices. The composition of the present invention can be applied onto a substrate and cured to form an insulating layer. In this case, a pattern can be formed when the composition of the present invention is applied to a substrate, and then the composition can be cured to form an insulating layer of a desired pattern.

The curable composition of the present invention is suitable for use as a material for forming an insulating layer in a display device such as a touch panel or a display, or as a potting agent or sealing material for electronic and optical components. In this case, the insulating layer may be formed into any desired pattern as described above, if necessary. Therefore, a display device such as a touch panel or a display, which includes an insulating layer obtained by curing the curable composition of the present invention, is also an aspect of the present invention.

The curable composition of the present invention can be used to coat an article and then cured to form an insulating coating layer (insulating film). Therefore, the composition of the present invention can be used as an insulating coating agent. The curable composition of the present invention can also be cured to form a cured product, which can be used as an insulating coating layer.

The insulating film formed from the curable composition of the present invention can be used for various applications. In particular, it can be used as a component of an electronic device or as a material used in the process of manufacturing an electronic device. Electronic devices include electronic devices such as semiconductor devices and magnetic recording heads. For example, the curable composition of the present invention can be used as an insulating film for semiconductor devices such as LSIs, system LSIs, DRAMs, SDRAMs, RDRAMs, D-RDRAMs, and multi-chip module multilayer wiring boards, an interlayer insulating film for semiconductors, an etching stopper film, a surface protective film, a buffer coat film, a passivation film in LSIs, a cover coat for flexible copper-clad boards, a solder resist film, and a surface protective film for optical devices.

In addition to being used as a coating agent, the ultraviolet-curable composition of the present invention is also suitable for use as a potting agent or sealing agent, particularly as an insulating potting agent or sealing agent for electronic and electrical devices.

The present invention will be further described below with reference to examples, but the present invention is not limited to the following examples.

The curable organopolysiloxane composition of the present invention and its cured product will be described in detail with reference to the following examples. In the following formulas, Me and Vi represent a methyl group and a vinyl group, respectively. The physical properties in the examples and comparative examples were measured and evaluated as follows.

[Viscosity of Organopolysiloxane and Curable Organopolysiloxane Composition]
The viscosity (mPa·s) at 25° C. was measured using a rotational viscometer (E-type viscometer VISCONIC EMD manufactured by Tokimec Inc.).

[Preparation of Curable Organopolysiloxane Composition]
The materials in the amounts shown in Table 1 below were placed in a plastic container and thoroughly mixed using a planetary mixer to prepare a curable organopolysiloxane composition.

[Curing of the Curable Organopolysiloxane Composition]
A glass substrate (50×50 mm ² ; thickness 0.75 mm) whose surface was covered with ITO was partially masked with polyimide tape. Approximately 0.5 mL of the curable organopolysiloxane composition was dropped onto the substrate, and a coating was produced using a spin coater (1H-360S, manufactured by Mikasa Co., Ltd.). The rotation speed of the spin coater was adjusted so that the thickness of the coating layer after curing was 10 to 20 μm. The resulting coating was heated at 70° C. for 30 minutes to produce a cured organopolysiloxane thin film.

[Dielectric constant of thin film of cured organopolysiloxane]
An aluminum electrode was prepared on the prepared cured thin film by vacuum deposition. After removing the masked polyimide tape, the capacitance was measured at room temperature (23°C) and 100 KHz using a Keysight Technologies 4294A precision impedance analyzer. The relative dielectric constant was calculated using the measured capacitance value, the thickness of the cured thin film measured separately, and the electrode area value.

[Preparation of polysilsesquioxane having a cage-shaped molecular structure: Production Example 1]
75.1 g of hexenyltrimethoxysilane and 350 mL of tetrahydrofuran were added to a three-neck flask with an internal volume of 500 mL to obtain a homogeneous solution, to which an aqueous solution consisting of 0.20 g of potassium hydroxide and 10.1 g of water was slowly added. The mixture was heated to reflux at 75° C. for 6 hours under stirring. After cooling, the mixture was neutralized and the volatile components were removed under reduced pressure to prepare a hexenyl-substituted polysilsesquioxane having a cage molecular structure. The isolation yield was 98%. Analysis by gel permeation chromatography (GPC) showed that the polysilsesquioxane had a polystyrene-equivalent M _w of 1790, M _n of 1720, and M _w /M _n of 1.04. Analysis by silicon-29 nuclear magnetic resonance ( ²⁹ Si-NMR) showed that the proportion of partially cleaved structural units in the total siloxane structural units of this polysilsesquioxane was 7 mol%.

[Preparation of polysilsesquioxane having a cage-shaped molecular structure: Production Example 2]
A mixture of 58.0 g of hexyltrimethoxysilane and 19.2 g of hexenyltrimethoxysilane was used instead of 75.1 g of hexenyltrimethoxysilane, 0.89 g of a 50% by mass aqueous solution of cesium hydroxide was used instead of 0.20 g of potassium hydroxide, and the amount of water was 10.3 g. The reaction was carried out in the same manner as in Production Example-1 to prepare a hexyl- and hexenyl-substituted polysilsesquioxane having a cage molecular structure. The isolated yield was 97%. Similarly, as a result of analysis by the GPC method, the polysilsesquioxane had a polystyrene-equivalent _Mw of 1820, _Mn of 1690, and _Mw / _Mn of 1.08. Furthermore, as a result of analysis by the ²⁹ Si-NMR method, the proportion of partially cleaved structural units in the total siloxane structural units of this polysilsesquioxane was 7 mol%.

[Examples and Comparative Examples]
Curable organopolysiloxane compositions having the compositions (parts by weight) shown in Table 1 were prepared using the components listed below. (A1) A vinyl group-containing organopolysiloxane consisting of (Me ₂ ViSiO _1/2 ) units, (Me ₂ SiO _2/2 ) units, and (SiO _4/2 ) units, having a vinyl group content of 0.93% by mass, and a viscosity of 200 mPa·s. (A2) An organohydrogenpolysiloxane consisting of (Me ₃ SiO _1/2 ) units, (Me ₂ SiO _2/2 ) units, and (MeHSiO _2/2 ) units, having a hydrogen content of 0.77% by mass, and a viscosity of 5 mPa·s. (A3) A silicone resin consisting of 70% by mass of (Me ₂ ViSiO _1/2 ) units and (SiO _4/2 ) units and having a vinyl group content of 3.4% by mass, and a mixture of (Me ₂ ViSiO _1/2 ) units and (Me ₂ (A3) _A silicone resin polysiloxane masterbatch consisting of 30 mass% of a vinyl-terminated organopolysiloxane having a vinyl group content of 1.53 mass% and a viscosity of 60 mPa·s, which is composed of (Me ₂ ViSiO _1/2 ) units and (Me ₂ SiO _2/2 ) units, a vinyl group content of 0.09 mass% and a viscosity of 39,000 mPa·s, and 32 mass% of fumed silica.
(A5) A vinyl-terminated organopolysiloxane comprising (Me ₂ ViSiO _1/2 ) units and (Me ₂ SiO _2/2 ) units, having a vinyl group content of 0.22% by mass, and a viscosity of 2,000 mPa·s. (A6) An organopolysiloxane comprising (Me ₂ HSiO _1/2 ) units and (SiO _4/2 ) units, having a silicon-bonded hydrogen group content of 0.96% by mass. (A7) An organopolysiloxane comprising (Me ₂ HSiO _1/2 ) units and (Me ₂ SiO _2/2 ) units, having a silicon-bonded hydrogen group content of 0.125% by mass. (B1) The hexenyl-substituted polysilsesquioxane prepared in Production Example 1 above. (B2) The hexyl- and hexenyl-substituted polysilsesquioxane prepared in Production Example 2 above. (C) A solution of platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex in polydimethylsiloxane both ends of which are blocked with dimethylvinyl, having a platinum content of 0.7 mass%.
(D) 1-ethynylcyclohexan-1-ol.

The results of the examples show that the curable organopolysiloxane composition of the present invention has a sufficiently low viscosity and is suitable for coating applications, even though it does not contain an organic solvent. It was also confirmed that the relative dielectric constant of the cured product obtained from the composition is extremely low.

The curable composition of the present invention is particularly suitable for the above-mentioned applications, in particular as a material for forming insulating layers in display devices such as touch panels and displays.

Claims (5)

(A) a linear organohydrogenpolysiloxane having an average of at least 3 silicon-bonded hydrogen atoms per molecule and a viscosity of 5 mPa.s at 25° C.;
A curable composition comprising: (B ) a polysilsesquioxane having a cage molecular structure having an alkenyl group; and (C1) a hydrosilylation reaction catalyst, wherein the mass ratio of component (A) to component (B) is (50-99):(50-1) (component (A):component (B)), curing reactive groups of component (A) and component (B) are selected so that component (A) and component (B) can crosslink, component (A) and component (B) are crosslinked by a hydrosilylation reaction, and the relative dielectric constant of the cured product after curing is less than 2.8; and the viscosity of the entire composition is in the range of 5-9 mPa.s at 25°C . The curable composition according to claim 1, wherein the polysilsesquioxane having a cage molecular structure of component (B) has an average number of silicon atoms per molecule of 8 to 20, a number average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC) is in the range of 500 to 3,000, and a molecular weight dispersity ( _Mw / _Mn ) is 1.0 to 1.5. A coating agent comprising the curable composition according to any one of claims 1 to 2 . A method for using a cured product of the curable composition according to any one of claims 1 to 2 as an insulating coating layer. A touch panel or a display device other than a touch panel, comprising a layer made of a cured product of the curable composition according to claim 1 .