JP7632468B2 - Photocurable composition, cured product thereof, and method for producing the cured product - Google Patents

Description

The present disclosure relates to a photocurable composition, a cured product thereof, and a method for producing the cured product, and belongs to the technical fields of heat-resistant materials, insulating materials, electronic materials, and automobiles. More specifically, the present disclosure relates to a photocurable composition containing an organosilicon compound having a hydrosilylation-reactive carbon-carbon unsaturated group and a hydrosilyl group, and a hydrosilylation catalyst. The cured product of the photocurable composition is useful as a heat-resistant insulating material.

2. Description of the Related Art In recent years, with the miniaturization, high integration and high performance of electronic devices and automobile parts, there has been an increasing demand for high heat resistance of various protective films and insulating films used therein.
From the viewpoints of workability, optical properties, chemical resistance, heat resistance, weather resistance, and the like, siloxane-based compounds such as silicone, which are organic-inorganic composite materials, have been used, and addition-curing silsesquioxane derivatives have attracted particular attention from the viewpoints of high heat resistance and workability.

International Publication No. 2005/010077 discloses a thermosetting, highly heat-resistant silsesquioxane derivative in which a carbon-carbon unsaturated bond group and a hydrosilyl group are both bonded to a silicon atom of a T structure in the same molecule.

International Publication No. 2009/066608 discloses a thermosetting, highly heat-resistant silsesquioxane derivative having a carbon-carbon unsaturated bond group and a hydrosilyl group in the same molecule and having a T structure, a D structure, and an M structure.

However, in order to cure the silsesquioxane derivatives disclosed in WO 2005/010077 and WO 2009/066608 by hydrosilylation crosslinking, a heat treatment is essential, and therefore the substrate to which it is applied is limited to one that can withstand the heating temperature. In addition, long periods of heating are required for curing, resulting in problems in productivity.
According to one embodiment of the present invention, it is possible to provide a photocurable composition containing a silsesquioxane derivative that has excellent curability and can be applied to various substrates, a cured product thereof, and a method for producing the cured product.

The present invention includes the following aspects [1] to [11].
[1]
A photocurable composition comprising a silsesquioxane derivative represented by the following formula (1) and a hydrosilylation catalyst containing a transition metal:

[In formula (1),
R ¹ is an organic group having 2 to 12 carbon atoms and a hydrosilylation-reactive carbon-carbon unsaturated bond,
^R2 is at least one selected from the group consisting of an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, and an aralkyl group having 7 to 10 carbon atoms;
each of a plurality of R ^3's and R ^4's is independently at least one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aralkyl group having 7 to 10 carbon atoms, and an organic group having 2 to 12 carbon atoms and a hydrosilylation reactive carbon-carbon unsaturated bond;
A plurality of R ³ 's may be the same or different.
A plurality of R ⁴ 's may be the same or different.
u, v, w and x each independently represent 0 or a positive number, at least one of which is a positive number;
Each of y and z is independently 0 or a positive number;
0≦y/(u+v+w+x)≦2.0,
0≦z/(u+v+w+x)≦2.0,
However, when v=0, at least one of the multiple R ^3's and R ⁴ 's is a hydrogen atom, and when w=0, at least one of the multiple R ^3's and R ^4's is an organic group having 2 to 12 carbon atoms and a carbon-carbon unsaturated bond capable of undergoing a hydrosilylation reaction.
[2]
The photocurable composition according to [1], wherein the ratio of the number of hydrogen atoms bonded to silicon atoms to one organic group having a hydrosilylation reactive carbon-carbon unsaturated bond present in the silsesquioxane derivative is 0.5 to 5.0.
[3]
The photocurable composition according to [1] or [2], wherein the content of the transition metal is 0.1 to 30,000 ppm by weight based on 100 parts by weight of the silsesquioxane derivative.
[4]
The photocurable composition according to any one of [1] to [3], wherein the transition metal is a platinum group metal.
[5]
The photocurable composition according to any one of [1] to [4], wherein the hydrosilylation catalyst containing a transition metal is at least one selected from the group consisting of β-diketonato platinum complexes, (η-cyclopentadienyl)trialkyl platinum complexes, (η ^-1,5 -cyclooctadiene)diaryl platinum complexes, and dialkyl azodicarboxylate platinum complexes.
[6]
The photocurable composition according to any one of [1] to [5], further comprising a heat resistance improver.
[7]
A cured product obtained by curing the photocurable composition according to any one of [1] to [6].
[8]
The cured product according to [7], having a dielectric constant of 4.0 or less at 1 MHz.
[9]
The cured product according to [7] or [8], which has a 5% weight loss temperature in air in thermogravimetry of 300° C. or higher.
[10]
The cured product according to any one of [7] to [9], which is an insulating film.
[11]
A method for producing a cured product, comprising a step of curing the photocurable composition according to any one of [1] to [6] by irradiating it with ultraviolet light.

According to one embodiment of the present invention, it is possible to provide a photocurable composition containing a silsesquioxane derivative that has excellent curability and can be applied to various substrates, a cured product thereof, and a method for producing the cured product.

The present disclosure relates to a photocurable composition, a cured product thereof, and a method for producing the cured product.
The present disclosure will be described in detail below.
In addition, unless otherwise specified, "%" means "% by weight", "parts" means "parts by weight", and "ppm" means "ppm by weight". In addition, in this disclosure, the description "lower limit to upper limit" indicating a numerical range means "not less than the lower limit, not more than the upper limit", and the description "upper limit to lower limit" means "not more than the upper limit, not less than the lower limit". In other words, it represents a numerical range including the upper limit and the lower limit. Furthermore, in this disclosure, a combination of two or more of the preferred embodiments described below is also a preferred embodiment.
In the present disclosure, the term "process" refers not only to an independent process, but also to a process that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved.

Below, we will explain the silsesquioxane derivatives, the method for producing the silsesquioxane derivatives, the hydrosilylation catalyst, the photocurable composition, the cured product thereof, the method for producing the cured product, and applications.

The silsesquioxane derivative according to the present disclosure is a silsesquioxane derivative represented by the following formula (1): The silsesquioxane derivative represented by the following formula (1) has, in the same molecule, an organic group having a carbon-carbon unsaturated bond capable of undergoing a hydrosilylation reaction and a hydrosilyl group.

The structural units that the silsesquioxane derivatives according to the present disclosure may have are referred to as structural units (a) to (f) as follows, and are described below.

Structural unit (a): (SiO _4/2 ) _u

Structural unit (b): (HSiO _3/2 ) _v

Structural unit (c): (R ¹ SiO _3/2 ) _w

Structural unit (d): (R ² SiO _3/2 ) _x

Structural unit (e): (R ³ ₂ SiO _2/2 ) _y

Structural unit (f): (R ⁴ ₃ SiO _1/2 ) _z

The silsesquioxane derivative according to the present disclosure can contain the above-mentioned structural units (a) to (f).
In formula (1), u, v, w and x are each independently 0 or a positive number, at least one of which is a positive number, y and z are each independently 0 or a positive number, 0≦y/(u+v+w+x)≦2.0, and 0≦z/(u+v+w+x)≦2.0.
That is, u, v, w, x, y, and z in formula (1) represent the molar ratio of each of the constituent units. In addition, in formula (1), u, v, w, x, y, and z represent the relative molar ratio of each of the constituent units contained in the silsesquioxane derivative according to the present disclosure represented by formula (1). That is, the molar ratio is the relative ratio of the total number of each of the constituent units represented by formula (1). The molar ratio can be determined from the NMR (nuclear magnetic resonance) analysis value of the silsesquioxane derivative according to the present disclosure. In addition, when the reaction rate of each raw material of the present silsesquioxane derivative is clear or the yield is 100%, it can be determined from the amount of the raw material charged.

Each of the structural units (c), (d), (e), and (f) in formula (1) may be of only one type, or may be of two or more types. Furthermore, the order of arrangement in formula (1) indicates the composition of the structural units, but does not mean the order of arrangement. Therefore, the condensation form of the structural units in the silsesquioxane derivative according to the present disclosure does not necessarily have to be the order of arrangement in formula (1).

1-1. Structural unit (a): (SiO _4/2 ) _u
The structural unit (a) is a so-called Q unit having four O _1/2 's (two oxygen atoms) per silicon atom. The Q unit means a unit having four O _1/2 's per silicon atom.
The proportion of the structural unit (a) in the silsesquioxane derivative according to the present disclosure is not particularly limited, but in consideration of the viscosity of the photocurable composition according to the present disclosure and the flexibility of the cured product thereof, the molar ratio (u/(u+v+w+x+y+z)) of the structural unit to all structural units is preferably 0.5 or less, more preferably 0.4 or less, even more preferably 0.3 or less, and even more preferably 0. Here, a molar ratio of 0 means that the structural unit is not included, and the same applies hereinafter.

1-2. Structural unit (b): (HSiO _3/2 ) _v
The structural unit (b) is a so-called T unit having three O _1/2 (1.5 oxygen atoms) per silicon atom, and has a hydrogen atom bonded to the silicon atom. The T unit means a unit having three O _1/2 per silicon atom.
That is, the structural unit (b) has a hydrosilyl group capable of undergoing a hydrosilylation reaction.
The proportion of the structural unit (b) in the silsesquioxane derivative according to the present disclosure is not particularly limited, but in consideration of the heat resistance, oxidation resistance, weather resistance, and insulating properties of the photocurable composition of the present disclosure and the cured product thereof, the molar ratio (v/(u+v+w+x+y+z)) of the structural unit (b) to all structural units is preferably 0 to 0.7, and in consideration of the heat resistance, oxidation resistance, and weather resistance as an insulating film, it is more preferably 0 to 0.1.

1-3. Structural unit (c): (R ¹ SiO _3/2 ) _w
The structural unit (c) is a T unit having three O _1/2 's (1.5 oxygen atoms) per silicon atom, and has R ¹ bonded to the silicon atom.
^R1 represents an organic group having 2 to 12 carbon atoms and a hydrosilylation-reactive carbon-carbon unsaturated bond, that is, this organic group ^R1 is preferably a functional group having a hydrosilylation-reactive carbon-carbon double bond or carbon-carbon triple bond.
Specific examples of such an organic group R ¹ include, but are not limited to, a vinyl group, an orthostyryl group, a methstyryl group, a parastyryl group, an acryloyloxymethyl group, a methacryloyloxymethyl group, a 2-acryloyloxyethyl group, a 2-methacryloyloxyethyl group, a 3-acryloyloxypropyl group, a 3-methacryloyloxypropyl group, an 8-acryloyloxyoctyl group, an 8-methacryloyloxyoctyl group, Examples include 1-propenyl group, 2-propenyl group, 1-methylethenyl group, 1-butenyl group, 3-butenyl group, 1-pentenyl group, 4-pentenyl group, 3-methyl-1-butenyl group, 1-phenylethenyl group, 2-phenylethenyl group, ethynyl group, 1-propynyl group, 2-propynyl group, 1-butynyl group, 3-butynyl group, 1-pentynyl group, 4-pentynyl group, 3-methyl-1-butynyl group, and phenylbutynyl group.
From the viewpoints of hydrosilylation reactivity and the heat resistance, oxidation resistance and/or weather resistance of the cured product, R ¹ is preferably a hydrocarbon group having a carbon-carbon double bond, more preferably a vinyl group and a 2-propenyl group (allyl group) having a small number of carbon atoms, or an aromatic orthostyryl group, metastyryl group and parastyryl group, and even more preferably a vinyl group.
The silsesquioxane derivative represented by formula (1) may contain two or more organic groups R ¹ as a whole, and in this case, all the organic groups R ¹ may be the same as or different from each other. For example, when they are different, a vinyl group and a parastyryl group may be present.

The proportion of structural unit (c) in the silsesquioxane derivative according to the present disclosure is not particularly limited, but in consideration of the heat resistance, oxidation resistance, weather resistance and insulating properties of the photocurable composition of the present disclosure and the cured product thereof, the molar ratio (w/(u+v+w+x+y+z)) of the structural unit (c) to all structural units is preferably 0 to 0.5, and more preferably 0.1 to 0.3.

1-4. Structural unit (d): (R ² SiO _3/2 ) _x
The structural unit (d) is a T unit having three O _1/2 's (1.5 oxygen atoms) per silicon atom, and has R ² bonded to the silicon atom.
^R2 is at least one selected from the group consisting of an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, and an aralkyl group having 7 to 10 carbon atoms. The structural unit (d) differs from the structural units (b) and (c) described above in that it does not contain a hydrogen atom and does not contain an organic group having a carbon-carbon unsaturated bond capable of hydrosilylation reaction.
The structural unit (d) basically forms three siloxane bonds per silicon atom in the photocurable composition and the cured product thereof, but does not form crosslinks by hydrosilylation reaction, and has one organic group with an appropriate number of carbon atoms per silicon atom, which contributes to improving the heat resistance, oxidation resistance, insulating properties, adhesion to substrates, and/or flexibility of the photocurable composition and the cured product thereof of the present disclosure. In addition, the amount of hydrogen atoms remaining in the cured product of the photocurable composition of the present disclosure can be reduced.

The alkyl group having 1 to 10 carbon atoms may be either an aliphatic group or an alicyclic group, and may be either linear or branched. Although not particularly limited, examples include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl groups. From the viewpoint of heat resistance, preferred are methyl and ethyl groups, and more preferred is methyl.

The aryl group having 6 to 10 carbon atoms is not particularly limited, but examples include a phenyl group, a group in which one or more hydrogen atoms of a phenyl group are substituted with an alkyl group having 1 to 4 carbon atoms, and a naphthyl group. From the viewpoint of heat resistance, a phenyl group is preferable.

The aralkyl group having 7 to 10 carbon atoms is not particularly limited, but examples include an alkyl group having 1 to 4 carbon atoms in which one of the hydrogen atoms is substituted with an aryl group such as a phenyl group. Examples include a benzyl group and a phenethyl group, and from the viewpoint of heat resistance, a benzyl group is preferred.

The silsesquioxane derivative represented by formula (1) may contain two or more organic groups ^R2 as a whole, and in that case, all of the organic groups ^R2 may be the same as or different from one another.

The proportion of the structural unit (d) in the silsesquioxane derivative according to the present disclosure is not particularly limited, but the molar ratio (x/(u+v+w+x+y+z)) of the structural unit (d) to all structural units is preferably 0 to 0.7 in consideration of the heat resistance, oxidation resistance, weather resistance, and insulating properties of the photocurable composition and its cured product according to the present disclosure, and more preferably 0.3 to 0.6 in consideration of the heat resistance, oxidation resistance, and weather resistance as an insulating film.

1-5. Structural unit (e): (R ³ ₂ SiO _2/2 ) _y
The structural unit (e) is a so-called D unit having two O _1/ 2's (one oxygen atom) per silicon atom. The D unit means a unit having two O _1/ 2's per silicon atom.
Each of the multiple R ^3s is independently at least one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aralkyl group having 7 to 10 carbon atoms, and an organic group having 2 to 12 carbon atoms and a carbon-carbon unsaturated bond capable of hydrosilylation, and the multiple R ^3s may be the same or different. Examples of these substituents include the same substituents as those exemplified for R ¹ of the structural unit (c) and R ² of the structural unit (d) described above.
The structural unit (e) is a D unit, and therefore contributes to lowering the viscosity of the photocurable composition of the present disclosure and improving the flexibility, heat resistance, oxidation resistance, and/or insulating properties of the cured product thereof.
From the viewpoints of heat resistance, availability of raw materials, and imparting flexibility to the cured product, it is preferable that a plurality of R ^3s are each independently a methyl group or a phenyl group.

The proportion of the structural unit (e) in the silsesquioxane derivative according to the present disclosure is not particularly limited, but in consideration of the low viscosity of the photocurable composition according to the present disclosure and the weather resistance and flexibility of the cured product thereof, the molar ratio (y/(u+v+w+x)) relative to all Q units and T units is preferably 0≦y/(u+v+w+x)≦2.0, more preferably 0.1 to 1.0, and even more preferably 0.1 to 0.5. However, when v=0, at least one of the multiple R ^3s and the multiple R ^4s in the structural unit (f) described below is a hydrogen atom, and when w=0, at least one of the multiple R ^3s and R ^4s is an organic group having 2 to 12 carbon atoms and a carbon-carbon unsaturated bond capable of undergoing a hydrosilylation reaction.

1-6. Structural unit (f): (R ⁴ ₃ SiO _1/2 ) _z
The structural unit (f) is a so-called M unit having one O _1/2 (0.5 oxygen atoms) per silicon atom. The M unit means a unit having one O _1/2 per silicon atom.
Each of the multiple R ^4s is independently at least one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aralkyl group having 7 to 10 carbon atoms, and an organic group having 2 to 12 carbon atoms and a carbon-carbon unsaturated bond capable of hydrosilylation, and the multiple R ^4s may be the same or different. Examples of these substituents include the same substituents as those exemplified for R ¹ in the structural unit (c) and R ² in the structural unit (d) described above.
The structural unit (f) is an M unit, and therefore contributes to lowering the viscosity of the photocurable composition of the present disclosure and improving the flexibility and/or insulating properties of the cured product thereof.

Since the M unit in the silsesquioxane derivative according to the present disclosure has one siloxane bond bonded to a silicon atom, it has high flexibility, and therefore when the multiple R ^4s are each independently an organic group having a hydrogen atom or a hydrosilylation-reactive carbon-carbon unsaturated bond, the hydrosilylation reactivity is generally higher and the curing reaction proceeds more smoothly than when these groups are bonded to the T unit and the D unit. Also, when the multiple R ^4s are each independently an organic group having 2 to 12 carbon atoms and a hydrogen atom or a hydrosilylation-reactive carbon-carbon unsaturated bond, the M unit in the cured product is incorporated into the skeleton of the cured product via two bonds, the siloxane bond and the hydrosilylation crosslink, and therefore the heat resistance and weather resistance of the cured product are improved compared to when R ⁴ does not have such a group.
For this reason, it is preferable that at least one of the three ^R4s in the structural unit (f) is a hydrogen atom or an organic group having a hydrosilylation reactive carbon-carbon unsaturated bond and having 2 to 12 carbon atoms. From the viewpoints of heat resistance and ease of availability of raw materials, the organic group having 2 to 12 carbon atoms and having a hydrosilylation reactive carbon-carbon unsaturated bond is preferably a vinyl group.

From the viewpoint of improving the flexibility, heat resistance, and weather resistance of the cured product, it is preferable that at least one of the three ^R4s in the structural unit (f) is at least one selected from the group consisting of an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, and an aralkyl group having 7 to 10 carbon atoms. From the viewpoints of heat resistance, ease of availability of raw materials, and imparting flexibility to the cured product, a methyl group or a phenyl group is preferable.

The proportion of the structural unit (f) in the silsesquioxane derivative according to the present disclosure is not particularly limited, but in consideration of the low viscosity of the photocurable composition according to the present disclosure and the weather resistance and flexibility of the cured product thereof, the molar ratio (z/(u+v+w+x)) to all Q units and T units is preferably 0≦z/(u+v+w+x)≦2.0, more preferably 0.1 to 1.0, and even more preferably 0.1 to 0.5.
However, when v=0, at least one of ^R3 and ^R4 in the aforementioned structural unit (e) is a hydrogen atom, and when w=0, at least one of ^R3 and ^R4 is an organic group having 2 to 12 carbon atoms and a carbon-carbon unsaturated bond capable of undergoing a hydrosilylation reaction.

1-7. Other structural units (g)
The silsesquioxane derivative according to the present disclosure can further include (R ⁵ O _1/2 ) as a structural unit that does not contain Si (hereinafter, referred to as structural unit (g)).
Here, ^R5 is a hydrogen atom and/or an alkyl group having 1 to 6 carbon atoms, which may be either an aliphatic group or an alicyclic group, and may be either linear or branched. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group.

This structural unit is either an alkoxy group, which is a hydrolyzable group contained in the raw material monomer described below, or an alkoxy group generated when an alcohol contained in the reaction solvent replaces a hydrolyzable group in the raw material monomer, and which remains in the molecule without undergoing hydrolysis or polycondensation, or a hydroxyl group which remains in the molecule after hydrolysis without undergoing polycondensation.

1-8. The ratio of the number of hydrogen atoms bonded to silicon atoms to one organic group having a hydrosilylation-reactive carbon-carbon unsaturated bond present in the silsesquioxane derivative according to the functional basic disclosure of the hydrosilylation reaction is not particularly limited, but from the viewpoints of the heat resistance, oxidation resistance, and weather resistance of the cured product, it is preferably 0.5 to 5.0, more preferably 0.8 to 3.0, and even more preferably 0.9 to 1.5.

1-9. Molecular Weight, etc. The weight average molecular weight (hereinafter referred to as "Mw") of the silsesquioxane derivative according to the present disclosure is not particularly limited, but is preferably in the range of 300 to 30,000. Such a silsesquioxane derivative is itself a liquid, has a low viscosity suitable for handling, is easily soluble in an organic solvent, the viscosity of the solution is easy to handle, and has excellent storage stability. Mw is more preferably 500 to 15,000, even more preferably 700 to 10,000, and particularly preferably 1,000 to 5,000.
In the present disclosure, Mw refers to a value obtained by converting the molecular weight measured by GPC (gel permeation chromatography) using polystyrene as a standard substance. The measurement conditions for Mw can be, for example, the measurement conditions in the Examples described below.

The state of the silsesquioxane derivative according to the present disclosure is not particularly limited, and may be, for example, liquid, solid, or semi-solid. It is preferably a liquid, and its viscosity is not particularly limited, and its viscosity at 25°C is preferably 1,000,000 mPa·s or less, more preferably 100,000 mPa·s or less, even more preferably 80,000 mPa·s or less, and particularly preferably 50,000 mPa·s or less. The lower limit of the viscosity is not particularly limited, and is, for example, 1 mPa·s.
In this disclosure, the viscosity refers to a value measured at 25° C. using an E-type viscometer (a cone-plate type viscometer, for example, TVE22H type viscometer manufactured by Toki Sangyo Co., Ltd.).

2. Method for Producing Silsesquioxane Derivative The silsesquioxane derivative according to the present disclosure can be produced by a known method. Methods for producing silsesquioxane derivatives are disclosed in detail as methods for producing polysiloxanes in International Publication No. WO 2005/01007, International Publication No. WO 2009/066608, International Publication No. WO 2013/099909, JP 2011-052170 A, and JP 2013-147659 A, etc.

The silsesquioxane derivative according to the present disclosure can be produced, for example, by the following method.
That is, the method for producing a silsesquioxane derivative according to the present disclosure can include a condensation step in which a raw material monomer is hydrolyzed and polycondensed in a suitable reaction solvent to give the structural unit in the above formula (1). In this condensation step, for example, a silicon compound having four siloxane bond-forming groups forming the structural unit (a) (Q unit) (hereinafter referred to as "Q monomer"), a silicon compound having three siloxane bond-forming groups forming the structural units (b) to (d) (T unit) (hereinafter referred to as "T monomer"), a silicon compound having two siloxane bond-forming groups forming the structural unit (e) (D unit) (hereinafter referred to as "D monomer"), and a silicon compound having one siloxane bond-forming group forming the structural unit (f) (M unit) (hereinafter referred to as "M monomer") can be used.

The method for producing a silsesquioxane derivative according to the present disclosure preferably includes a distillation step in which the raw material monomer is subjected to a hydrolysis/polycondensation reaction in the presence of a reaction solvent, and then the reaction solvent, by-products, residual monomers, water, etc. in the reaction liquid are distilled off.

2-1. Raw Material Monomers The siloxane bond-forming groups contained in the raw material monomers Q monomer, T monomer, D monomer, and M monomer are hydroxyl groups and/or hydrolyzable groups. Among these, examples of the hydrolyzable groups include halogeno groups, alkoxy groups, and siloxy groups. In the condensation step, the hydrolyzable group is preferably an alkoxy group, more preferably an alkoxy group having 1 to 3 carbon atoms, because it has good hydrolysis properties and does not by-produce acid. In addition, in the M monomer, the hydrolyzable group is preferably a siloxy group because of the ease of obtaining the raw material, and a disiloxane consisting of two structural units (f) can be used.

In the condensation step, the siloxane bond-forming groups of the Q monomer, T monomer, and D monomer corresponding to each of the constituent units are preferably alkoxy groups, and the siloxane bond-forming groups contained in the M monomer are preferably alkoxy groups or siloxy groups. Furthermore, the monomers corresponding to each of the constituent units may be used alone or in combination of two or more kinds.

Examples of the Q monomer that provides the structural unit (a) include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane.
Examples of the T monomer that provides the structural unit (b) include trimethoxysilane, triethoxysilane, tripropoxysilane, and trichlorosilane.
Examples of T monomers which provide the structural unit (c) include trimethoxyvinylsilane, triethoxyvinylsilane, trichlorovinylsilane, allyltrimethoxysilane, (p-styryl)trimethoxysilane, (p-styryl)triethoxysilane, (3-methacryloyloxypropyl)trimethoxysilane, (3-methacryloyloxypropyl)triethoxysilane, (3-acryloyloxypropyl)trimethoxysilane, (3-acryloyloxypropyl)triethoxysilane, (8-methacryloyloxyoctyl)trimethoxysilane, and (8-acryloyloxyoctyl)trimethoxysilane.
Examples of T monomers that provide the structural unit (d) include methyltrimethoxysilane, methyltriethoxysilane, methyltripoxysilane, methyltriisopropoxysilane, methyltrichlorosilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltriethoxysilane, butyltrimethoxysilane, cyclohexyltrimethoxysilane, cyclohexyltriethoxysilane, phenyltrimethoxysilane, and phenyltriethoxysilane.
Examples of D monomers which give the structural unit (e) include dimethoxydimethylsilane, dimethoxydiethylsilane, diethoxydimethylsilane, diethoxydiethylsilane, dipropoxydimethylsilane, dipropoxydiethylsilane, dimethoxymethylphenylsilane, diethoxymethylphenylsilane, dimethoxydiphenylsilane, diethoxydiphenylsilane, dimethoxybenzylmethylsilane, diethoxybenzylmethylsilane, dichlorodimethylsilane, dimethoxymethylsilane, dimethoxyphenylsilane, dimethoxymethylvinylsilane, diethoxymethylsilane, diethoxyphenylsilane, and diethoxymethylvinylsilane.
Examples of the M monomer that provides the structural unit (f) include hexamethyldisiloxane, hexaethyldisiloxane, hexapropyldisiloxane, 1,1,3,3-tetramethyldisiloxane, 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, which provide two structural units (f) upon hydrolysis, as well as methoxydimethylsilane, ethoxydimethylsilane, methoxydimethylvinylsilane, ethoxydimethylvinylsilane, methoxytrimethylsilane, ethoxytrimethylsilane, methoxydimethylphenylsilane, ethoxydimethylphenylsilane, chlorodimethylsilane, chlorodimethylvinylsilane, chlorotrimethylsilane, dimethylsilanol, dimethylvinylsilanol, trimethylsilanol, triethylsilanol, tripropylsilanol, and tributylsilanol.
Examples of the compound that reacts with the raw material monomer to give the structural unit (g) include water and alcohols such as methanol, ethanol, 1-propanol, 2-propanol, and 2-butanol.

The ratio of the raw material monomers Q monomer, T monomer, D monomer and M monomer to be charged may be appropriately set depending on the desired values of u to z in formula (1) in the present silsesquioxane derivative.

2-2. In the reaction solvent condensation step, an alcohol can be used as the reaction solvent. The alcohol according to the present disclosure is an alcohol in the narrow sense represented by the general formula R-OH, and is a compound having no functional groups other than an alcoholic hydroxyl group.
The alcohol is not particularly limited, but specific examples thereof include methanol, ethanol, 1-propanol, 2-propanol, 2-butanol, 2-pentanol, 3-pentanol, 2-methyl-2-butanol, 3-methyl-2-butanol, cyclopentanol, 2-hexanol, 3-hexanol, 2-methyl-2-pentanol, 3-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-3-pentanol, 2-ethyl-2-butanol, 2,3-dimethyl-2-butanol, and cyclohexanol. Of these, secondary alcohols such as 2-propanol, 2-butanol, 2-pentanol, 3-pentanol, 3-methyl-2-butanol, cyclopentanol, 2-hexanol, 3-hexanol, 3-methyl-2-pentanol, and cyclohexanol are preferably used.
In the condensation step, these alcohols can be used alone or in combination of two or more. More preferred alcohols are compounds that can dissolve water at the concentration required in the condensation step. Alcohols with such properties are compounds with a water solubility of 10 g or more per 100 g of alcohol at 20° C.

The amount of alcohol used in the condensation step, including the amount added during the hydrolysis and polycondensation reaction, is 0.5% by mass or more based on the total amount of all reaction solvents, thereby preventing gelation of the silsesquioxane derivative produced. The preferred amount is 1% by mass or more and 60% by mass or less, and more preferably 3% by mass or more and 40% by mass or less.

The reaction solvent used in the condensation step may be alcohol alone, or may be a mixed solvent with at least one auxiliary solvent. The auxiliary solvent may be either a polar solvent or a non-polar solvent, or a combination of both. Preferred polar solvents are secondary or tertiary alcohols having 3 or 7 to 10 carbon atoms, and diols having 2 to 20 carbon atoms.

Non-polar solvents include, but are not limited to, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, chlorinated hydrocarbons, ethers, amides, ketones, esters, and cellosolves. Of these, aliphatic hydrocarbons, alicyclic hydrocarbons, and aromatic hydrocarbons are preferred. Non-polar solvents include, but are not limited to, n-hexane, isohexane, cyclohexane, heptane, toluene, xylene, and methylene chloride, which form azeotropes with water, and the use of these compounds in combination makes it possible to efficiently remove water when removing the reaction solvent by distillation from the reaction mixture containing the silsesquioxane derivative after the condensation step. As a non-polar solvent, xylene, which is an aromatic hydrocarbon, is particularly preferred because of its relatively high boiling point.

2-3. Water and catalyst used in hydrolysis reaction The hydrolysis and polycondensation reaction in the condensation step is carried out in the presence of water.
The amount of water used to hydrolyze the hydrolyzable groups contained in the raw material monomer is preferably 0.5 to 5 times, more preferably 1 to 2 times the molar amount (mol) of the hydrolyzable groups.
The hydrolysis and polycondensation reaction of the raw material monomers may be carried out without a catalyst or with a catalyst. When a catalyst is used, an acid catalyst such as an inorganic acid, such as sulfuric acid, nitric acid, hydrochloric acid, or phosphoric acid, or an organic acid, such as formic acid, acetic acid, oxalic acid, or paratoluenesulfonic acid, is preferably used.
The amount of the acid catalyst used is preferably an amount corresponding to 0.01 to 20 mol %, and more preferably an amount corresponding to 0.1 to 10 mol %, based on the total amount (mol) of silicon atoms contained in the raw material monomers.

2-4. Other Additives The completion of the hydrolysis/polycondensation reaction in the condensation step can be appropriately detected by the methods described in various publications, etc. In addition, in the condensation step of the production of the silsesquioxane derivative according to the present disclosure, an auxiliary can be added to the reaction system.
Examples of such agents include antifoaming agents that suppress foaming of the reaction liquid, scale control agents that prevent scale adhesion to the reaction vessel or stirring shaft, polymerization inhibitors, hydrosilylation reaction inhibitors, etc. The amount of these agents used is arbitrary, but is preferably about 1 to 100% by weight based on the concentration of the silsesquioxane derivative according to the present disclosure in the reaction mixture.

2-5. Distillation of reaction solvent, etc. By providing a distillation step for distilling off the reaction solvent, by-products, residual monomers, water, catalyst, etc. contained in the reaction liquid obtained from the condensation step after the condensation step in the production of the silsesquioxane derivative according to the present disclosure, the stability of the produced silsesquioxane derivative according to the present disclosure can be improved. The distillation can be performed under normal pressure or reduced pressure, at room temperature or under heating, or under cooling.

3. Hydrosilylation Catalyst The photocurable composition of the present disclosure contains a hydrosilylation catalyst containing a transition metal, which allows the silsesquioxane derivative to be photocured.
The transition metal contained in the hydrosilylation catalyst is not particularly limited, and examples thereof include simple substances, metal complexes, metal salts, and metal oxides of metals belonging to Groups 8 to 10, such as iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, and platinum.
Of these, the hydrosilylation catalyst is preferably one containing one or more of the platinum group metals consisting of ruthenium, rhodium, palladium, osmium, iridium, and platinum. From the viewpoints of reactivity and availability, a catalyst containing platinum is more preferred, and a platinum complex is even more preferred.
The platinum complex is preferably at least one selected from the group consisting of β-diketonato platinum complexes, (η-cyclopentadienyl)trialkyl platinum complexes, (η ⁴ -1,5-cyclooctadiene)diaryl platinum complexes, and dialkyl azodicarboxylate platinum complexes. Particularly preferred platinum complexes are β-diketonato platinum complexes represented by the following formula (2), (η-cyclopentadienyl)trialkyl platinum complexes represented by the following formula (3), (η ⁴ -1,5-cyclooctadiene)diaryl platinum complexes represented by the following formula (4), and dialkyl azodicarboxylate platinum complexes containing a dialkyl azodicarboxylate as a ligand represented by the following formula (5).

[In formula (2), ^R6 and ^R7 are each independently at least one selected from the group consisting of a hydrogen atom, an alkyl group, and an aryl group, and may be the same or different from each other, and ^R8 , ^R9 , ^R10 , and ^R11 are each independently at least one selected from the group consisting of an alkyl group, an aryl group, and an alkoxy group, and may be the same or different from each other.]

(In formula (3), Cp is a cyclopentadienyl group η-bonded to a platinum atom, which may or may not be substituted with a substituent, and R ¹² , R ¹³ and R ¹⁴ each independently represent an aliphatic group having 1 to 18 carbon atoms σ-bonded to a platinum atom, which may be the same or different from each other.)

[In formula (4), R ¹⁵ is a linear, branched or cyclic alkadiene group π-bonded to a platinum atom, each of which may or may not have a substituent, R ¹⁷ and R ¹⁸ are each independently an aryl group σ-bonded to a platinum atom, each of which may or may not have a substituent and may be the same or different from each other, and R ¹⁶ and R ¹⁹ are each independently at least one selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxy group and a halogen atom, each of which may be the same or different from each other, may be substituted at any position of the aryl group, and each of which may be substituted with multiple substituents.]

In formula (5), each of the multiple R ^20s independently represents a hydrocarbon group having 1 to 6 carbon atoms and may be the same or different.
In addition, in formula (5), only the ligand is shown, and the platinum atom is omitted.

Specific examples of the β-diketonato platinum complexes represented by the formula (2) include bis(acetylacetonato)platinum(II).
Specific examples of the (η-cyclopentadienyl)trialkylplatinum complexes represented by the formula (3) include trimethyl(methylcyclopentadienyl)platinum(IV) and (cyclopentadienyl)trimethylplatinum(IV).
Specific examples of the (η ⁴ -1,5-cyclooctadiene)diarylplatinum complexes represented by the formula (4) include (η ⁴ -1,5-cyclooctadiene)bis(4-methoxyphenyl)platinum(II).
Specific examples of platinum complexes containing a dialkyl azodicarboxylate represented by the formula (5) as a ligand include diethyl azodicarboxylate platinum(II).
Among these compounds, bis(acetylacetonato)platinum(II) and trimethyl(methylcyclopentadienyl)platinum(IV) are more preferred.

The transition metal content is not particularly limited, but is preferably 0.1 to 30,000 ppm by weight, more preferably 1.0 to 10,000 ppm by weight, and even more preferably 10 to 2,000 ppm by weight, per 100 parts by weight of the total amount of the silsesquioxane derivative according to the present disclosure.

4. Photocurable Composition The photocurable composition of the present disclosure (hereinafter also referred to as the "composition of the present disclosure") contains the silsesquioxane derivative according to the present disclosure and a hydrosilylation catalyst.
The composition of the present disclosure has excellent flowability and, as described below, has excellent heat resistance and insulating properties when cured, making it a good insulating material for insulating elements that require heat resistance. In addition, the composition of the present disclosure can itself exhibit good curability and adhesive properties, and can be used as an adhesive composition or a binder composition.
The composition of the present disclosure contains the silsesquioxane derivative and a hydrosilylation catalyst, and may contain various other components (hereinafter referred to as "other components") as necessary.
As the other components, a heat resistance improver, a hydrosilylation reaction inhibitor, a solvent, and the like are preferable.
The other ingredients will be described below.

4-1. Heat Resistance Improver The composition of the present disclosure may contain a heat resistance improver.
The heat resistance improver is not particularly limited, and known ones can be used. Examples of the heat resistance improver include iron 2-ethylhexanoates such as iron tris(2-ethylhexanoate)(III), cerium 2-ethylhexanoates such as cerium tris(2-ethylhexanoate)(III), and zirconium 2-ethylhexanoates such as zirconium tetra(2-ethylhexanoate)(IV) and zirconium bis(2-ethylhexanoate)(IV), as well as metal oxides such as iron oxide, cerium oxide, and zirconium oxide.
The proportion of the heat resistance improver used is not particularly limited, but is, for example, 0 to 10,000 ppm by weight, preferably 1 to 1,000 ppm by weight, more preferably 5 to 500 ppm by weight, and even more preferably 10 to 300 ppm by weight, relative to 100 parts by weight of the total amount of the silsesquioxane derivative according to the present disclosure.
The addition of a heat resistance improver can improve or suppress a decrease in the thermal weight loss temperature, suppress a decrease in the relative dielectric constant and insulating properties, suppress the occurrence of cracks, and suppress coloration during use and storage under heating and at room temperature.

4-2. Hydrosilylation Reaction Inhibitor The composition of the present disclosure may contain a hydrosilylation reaction inhibitor.
By doing so, the storage stability of the composition of the present disclosure can be improved. There is no particular limitation on the hydrosilylation reaction inhibitor, and examples thereof include compounds that can be coordinated to a hydrosilylation catalyst metal, such as vinyl siloxanes such as methylvinyltetrasiloxane, acetylene alcohols such as 2-methyl-3-butyn-2-ol, siloxane-modified acetylene alcohols, hyperoxides, and known hydrosilylation reaction inhibitors containing a nitrogen atom, a sulfur atom, or a phosphorus atom. Among these, siloxane compounds having a structure in which a group having a carbon-carbon triple bond is bonded to a silicon atom, as disclosed in JP 2010-143973 A, are preferred, in that they have an appropriate reaction inhibition effect, are low in volatility, and suppress odor, coloration, and the like.
The proportion of the hydrosilylation reaction inhibitor used is not particularly limited, but is, for example, 0 to 5.0 wt %, preferably 0 to 2.0 wt %, and more preferably 0 to 1.0 wt %, relative to 100 parts by weight of the total amount of the silsesquioxane derivative according to the present disclosure.

4-3. Solvent The composition of the present disclosure, if it is a liquid substance, can be applied directly to the surface of a substrate, but can also be diluted with a solvent as necessary. When a solvent is used, a solvent that dissolves the silsesquioxane derivative according to the present disclosure is preferable, and examples of the solvent include various organic solvents such as aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, chlorinated hydrocarbon solvents, alcohol solvents, ether solvents, amide solvents, ketone solvents, ester solvents, and cellosolve solvents.
When a solvent is used, it is preferable to volatilize the solvent contained in the applied film prior to curing the composition of the present disclosure. The solvent may be volatilized in the air or in an inert gas atmosphere such as nitrogen. Heating may be performed to volatilize the solvent, and the heating temperature in this case is preferably less than 100°C.

4-4. Other Components Other Than the Above-described Components The composition of the present disclosure may contain other components other than the above-described components as necessary.
Specifically, it may contain any other auxiliary agent such as surfactants, antistatic agents (e.g., conductive polymers), leveling agents, photosensitizers, UV absorbers, antioxidants, stabilizers, lubricants, pigments, dyes, plasticizers, suspending agents, nanoparticles, nanofibers, nanosheets, and fillers, etc. It may also contain silane-based reactive diluents such as tetraalkoxysilanes, trialkoxysilanes, dialkoxysilanes, monoalkoxysilanes, and disiloxanes.
Furthermore, other photocurable compounds such as radically curable compounds and cationic curable compounds may also be contained, and a photopolymerization initiator therefor may also be contained.

5. Cured Product The cured product of the present disclosure is a cured product obtained by curing the above-described composition of the present disclosure.

The cured product of the present disclosure has excellent heat resistance. There are no particular limitations on the index of heat resistance, but examples thereof include thermal weight loss temperature, dielectric constant, insulation, coloration, adhesiveness, tackiness, light transparency, and crack generation.

5-1-1. Thermal weight loss temperature The cured product of the present disclosure has excellent heat resistance and a high thermal weight loss temperature. The thermal weight loss temperature can be determined by thermogravimetric differential thermal analysis (hereinafter referred to as TG/DTA). There is no particular limit to the measurement atmosphere, and the measurement can be performed in air or in an inert gas atmosphere such as nitrogen. The measurement atmosphere is appropriately selected in consideration of the environment in which the cured product of the present disclosure is used, but it is preferable to perform the measurement in air. There is no particular limit to the heating rate during measurement, and it can be, for example, 5, 10, or 20 ° C./min. Considering that it can be measured in a short time, 20 ° C./min is preferable. There is no particular limit to the index of the weight loss temperature, and it can be, for example, the temperature at the time when a certain percentage of the original weight is reduced, such as the weight loss start temperature and the 1, 5, or 10% weight loss temperature. It can also be expressed as the weight loss rate at a certain temperature, such as the weight loss rate at 400 ° C.

The 5% weight loss temperature of the cured product of the present disclosure, measured in air at 20°C/min, is, for example, 300°C or higher, preferably 370°C or higher, more preferably 400°C or higher, and particularly preferably 500°C or higher.

5-1-2. Dielectric constant The cured product of the present disclosure has a low dielectric constant and is excellent in insulation over a wide frequency band. The dielectric constant of the cured product of the present disclosure is not particularly limited, but is, for example, 4.0 or less, preferably 3.6 or less, and more preferably 3.5 or less. The frequency band in which the dielectric constant is used is not particularly limited, but is, for example, 1 kHz to 100 GHz, preferably 1 kHz to 1 GHz, and more preferably 1 kHz to 10 MHz. For example, the cured product of the present disclosure has a dielectric constant of 4.0 or less at 1 MHz.
When comparing the values of the dielectric constant between cured products, the measurement frequency is not particularly limited, but for example, the dielectric constant can be measured at 1 kHz, 10 kHz, 100 kHz, 1 MHz, 10 MHz, 1 GHz, etc., to compare the insulating properties of the cured products. In addition, the insulating properties can be evaluated by showing that the dielectric constant is equal to or lower than a certain value over a certain frequency band. The frequency band is not particularly limited, but for example, the dielectric constant from 1 kHz to 10 MHz can be shown.
In addition, the relative dielectric constant in this disclosure means a value measured at room temperature (23° C.±2° C.).

As described above, the cured product of the present disclosure has a low dielectric constant and excellent insulating properties over a wide frequency band. Therefore, the cured product of the present disclosure can be an insulating film.
The cured product (insulating film) of the present disclosure is obtained by curing the composition of the present disclosure, and the curing means is not particularly limited, but may be, for example, cured by irradiation with ultraviolet light. Details of the curing means will be described later in "Method for producing a cured product."

6. Method for Producing a Cured Product The method for producing a cured product (insulating film) of the present disclosure includes a step of curing the composition of the present disclosure by irradiating it with ultraviolet light. The obtained cured product (insulating film) may be the cured product (insulating film) of the present disclosure described above.
When the composition of the present disclosure is cured, for example, the composition of the present disclosure is applied to a suitable substrate, and then irradiated with light such as ultraviolet light to promote the hydrosilylation reaction and cure the composition.
The composition of the present disclosure may or may not contain a solvent. When the composition contains a solvent, it is preferable to remove the solvent before photocuring or the like, as described above.

When the composition of the present disclosure is used by coating it on a substrate, the coating method is not particularly limited, and for example, a typical coating method such as a casting method, a spin coating method, a bar coating method, a dip coating method, a spray coating method, a roll coating method, a flow coating method, or a gravure coating method can be used.
There is no particular limitation on the thickness to which the composition of the present disclosure is applied, and it may be appropriately set depending on the purpose.
There are no particular limitations on the substrate to which the composition of the present disclosure can be applied, and the composition can be applied to a variety of materials, including wood, metal, inorganic materials, plastics, paper, fibers, and fabrics.
Examples of metals include copper, silver, iron, aluminum, silicon, silicon steel, and stainless steel. Examples of inorganic materials include metal oxides such as aluminum oxide, silicon oxide, magnesium oxide, zirconium oxide, zinc oxide, indium tin oxide, and gallium oxide, metal nitrides such as aluminum nitride, gallium nitride, and silicon nitride, ceramics such as silicon carbide and boron nitride, mortar, concrete, and glass. Specific examples of plastics include acrylic resins such as polymethyl methacrylate, polyester resins such as polyethylene terephthalate, polyvinyl chloride resins, polycarbonate resins, epoxy resins, polyamide resins such as nylon and aramid, polyimide resins, polyamideimide resins, fluororesins such as tetrafluoroethylene resins, polyolefin resins such as cross-linked polyethylene resins, composite resins such as polychloroprene, polyphenylene sulfide, polysulfone, polyethersulfone, polyetheretherketone, polyurethane resins, and glass epoxy resins. Examples of fibers include natural fibers, regenerated fibers, semi-synthetic fibers, metal fibers, glass fibers, carbon fibers, ceramic fibers, and known chemical fibers. The fabric may be woven or nonwoven and may be made, for example, using the fibers described above.
These materials may be used alone, or two or more of them may be used in combination, mixture, or composite.
The shape of the substrate is not particularly limited, and examples thereof include a plate, a sheet, a film, a rod, a sphere, a fiber, a powder, and a structure having a complex shape.

6-2. Curing method In order to cure the composition of the present disclosure, active energy rays can be irradiated. Examples of active energy rays include electron beams, and light such as ultraviolet rays, visible light, and X-rays. Light is preferred, and ultraviolet rays are more preferred because inexpensive equipment can be used.
Examples of ultraviolet ray irradiation devices include high pressure mercury lamps, metal halide lamps, UV electrodeless lamps, and LEDs.
The irradiation energy should be appropriately set depending on the type of active energy rays and the formulation composition. For example, in the case of using a high-pressure mercury lamp, the irradiation energy in the UV-A region (315 nm to 400 nm) is preferably 0.1 to 30 J/ ^cm2 , more preferably 0.5 to 20 J/ ^cm2 , and even more preferably 1.0 to 15 J/ ^cm2 .

Furthermore, before and/or after the photocuring, heat curing can be appropriately combined.
For example, a two-stage curing process can be performed in which a substrate having a portion that is shaded when irradiated with light is impregnated with the composition of the present disclosure, and then the substrate is irradiated with light to first cure the composition of the present disclosure in the portion exposed to light, and then heat is applied to cure the composition of the present disclosure in the portion not exposed to light. There are no particular limitations on such substrates, and examples of the substrates include substrates having complex shapes such as fabric, fiber, powder, porous, and uneven shapes, and the substrates may have a shape in which two or more of these shapes are combined.

7. Applications The cured product of the composition of the present disclosure has excellent heat resistance, oxidation resistance, weather resistance, hardness, transparency, and flexibility, and materials having a cured film of the composition of the present disclosure can be used for various applications by taking advantage of these properties.
For example, it can be used in various industrial product fields such as the electrical and electronic fields. Particularly, specific examples of preferred applications include lighting devices such as LED lighting and organic EL lighting, semiconductor modules, electronic circuit boards such as printed wiring boards and flexible wiring boards, electric rotating devices such as small motors and in-vehicle motors, power supply devices such as transformers, power storage devices such as lithium batteries, and power generation devices such as solar panels.
For example, a composite material having a cured product of the composition of the present disclosure and the above-mentioned substrate is useful as a heat-resistant insulating member. As the substrate, the substrates described in the above section "6. Method for producing the cured product" can be used.

Next, the present disclosure will be specifically described based on examples and comparative examples, but the present disclosure is not limited to the following examples.
The weight average molecular weight (Mw) was determined by gel permeation chromatography (hereinafter referred to as "GPC") using a combination of GPC columns "TSK gel G4000HX" and "TSK gel G2000HX" (model names, manufactured by Tosoh Corporation) in a toluene solvent at 40°C, and the molecular weight was calculated from the retention time using standard polystyrene.
The molar ratio of each of the structural units in the obtained silsesquioxane derivative was calculated by dissolving the sample in deuterated chloroform, performing ^1H -NMR analysis, and, if necessary, performing ^29Si -NMR analysis. The alkoxysilane monomer reacted quantitatively and was introduced into the silsesquioxane derivative, but the M unit derived from the disiloxane monomer was not quantitatively introduced depending on the composition of the silsesquioxane derivative.

[Synthesis of silsesquioxane derivatives]
<Synthesis Example 1>
Trimethoxyvinylsilane (7.4 g, 50 mmol), methyltriethoxysilane (26.7 g, 150 mmol), dimethoxydimethylsilane (3.0 g, 25 mmol), 1,1,3,3-tetramethyldisiloxane (3.4 g, 25 mmol), xylene (15 g) and 2-propanol (15 g) were weighed out and placed in a 200 mL four-neck round-bottom flask equipped with a thermometer, a dropping funnel and a stirring blade, and thoroughly stirred in a water bath at about 20°C. A solution that had been separately prepared by mixing 1 mol/L aqueous hydrochloric acid solution (0.45 g, 4.4 mmol), pure water (11.4 g) and 2-propanol (4.5 g) was dropped into the flask from the dropping funnel over a period of about 1 hour, and stirring was continued overnight at room temperature. The solvent and the like were removed from the resulting solution at 60°C under reduced pressure, and 19 g of silsesquioxane derivative 1 was obtained as a colorless and transparent liquid.

<Synthesis Example 2>
Silsesquioxane derivative 2 was obtained as a colorless, transparent liquid by carrying out the same operation as for silsesquioxane derivative 1, except that allyltrimethoxysilane (50 mmol), phenyltrimethoxysilane (150 mmol), dimethoxydiphenylsilane (25 mmol), and 1,1,3,3-tetramethyldisiloxane (25 mmol) were used as raw material silane monomers.

<Synthesis Example 3>
Silsesquioxane derivative 3 was obtained as a colorless, transparent liquid by carrying out the same procedure as for silsesquioxane derivative 1, except that triethoxysilane (150 mmol), trimethoxyvinylsilane (50 mmol), dimethoxydimethylsilane (25 mmol), and 1,1,3,3-tetramethyldisiloxane (50 mmol) were used as raw material silane monomers.

<Synthesis Example 4>
Silsesquioxane derivative 4 was obtained as a colorless, transparent liquid by carrying out the same procedure as for silsesquioxane derivative 1, except that triethoxysilane (150 mmol), trimethoxyvinylsilane (50 mmol), and 1,1,3,3-tetramethyldisiloxane (50 mmol) were used as raw silane monomers.

<Synthesis Example 5>
Silsesquioxane derivative 5 was obtained as a colorless, transparent liquid by carrying out the same procedure as for silsesquioxane derivative 1, except that triethoxysilane (150 mmol), trimethoxyvinylsilane (25 mmol), (p-styryl)trimethoxysilane (25 mmol), and 1,1,3,3-tetramethyldisiloxane (50 mmol) were used as raw material silane monomers.

<Synthesis Example 6>
Silsesquioxane derivative 6 was obtained as a colorless, transparent liquid by carrying out the same procedure as for silsesquioxane derivative 1, except that triethoxysilane (200 mmol), dimethoxymethylsilane (75 mmol), and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane (50 mmol) were used as raw material silane monomers.

<Synthesis Example 7>
Silsesquioxane derivative 7 was obtained as a colorless, transparent liquid by carrying out the same operation as for silsesquioxane derivative 1, except that triethoxysilane (100 mmol), trimethoxyvinylsilane (100 mmol), and dimethoxymethylsilane (100 mmol) were used as raw silane monomers.

<Synthesis Example 8>
Silsesquioxane derivative 8 was obtained as a colorless, transparent liquid by carrying out the same procedure as for silsesquioxane derivative 1, except that triethoxysilane (150 mmol) and trimethoxyvinylsilane (120 mmol) were used as raw silane monomers.

<Synthesis Example 9>
Silsesquioxane derivative 9 was obtained as a colorless, transparent liquid by carrying out the same procedure as for silsesquioxane derivative 1, except that triethoxysilane (150 mmol), trimethoxyvinylsilane (50 mmol), phenyldimethoxysilane (25 mmol), and 1,1,3,3-tetramethyldisiloxane (50 mmol) were used as raw material silane monomers.

<Synthesis Example 10>
Silsesquioxane derivative 10 was obtained as a colorless, transparent liquid by carrying out the same operation as for silsesquioxane derivative 1, except that tetramethoxysilane (100 mmol), dimethoxydimethylsilane (100 mmol), 1,1,3,3-tetramethyldisiloxane (12.5 mmol), and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane (12.5 mmol) were used as raw material silane monomers.

<Synthesis Example 11>
Silsesquioxane derivative 11 was obtained as a colorless semisolid by carrying out the same operation as for silsesquioxane derivative 1, except that tetramethoxysilane (90 mmol), triethoxysilane (36 mmol), trimethoxyvinylsilane (30 mmol), dimethoxydimethylsilane (36 mmol), 1,1,3,3-tetramethyldisiloxane (7.5 mmol), and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane (22.5 mmol) were used as raw material silane monomers.

The compositions, Mw and molar ratios of each introduced structural unit for Synthesis Examples 1 to 11 are summarized in Tables 1 and 2.

<Reference Example 1>
[Synthesis of 3-acryloyloxypropylsilsesquioxane]
Except for using (3-acryloyloxypropyl)trimethoxysilane as the raw material silane monomer and using only 2-propanol as the reaction solvent, the same procedure as for silsesquioxane derivative 1 was carried out to obtain 3-acryloyloxypropylsilsesquioxane as a colorless, transparent liquid. The Mw was 2,370.
<Reference Example 2>
AC-SQ SI-20 (a composite derivative of 3-acryloyloxypropylsilsesquioxane and silicone) manufactured by Toagosei Co., Ltd. was used as is.

Example 1
(1) Preparation of photocurable composition
10 g of the silsesquioxane derivative obtained in Synthesis Example 1 and 10 mg of bis(acetylacetonato)platinum(II) (hereinafter referred to as Pt(acac) ₂ ) were weighed out and dissolved by stirring in a planetary centrifugal mixer.
(2) Confirmation of photohydrosilylation curing properties
The photocurable composition (1) described above was applied to a copper plate using a bar coater to form a coating of about 100 μm in thickness. Then, ultraviolet light was irradiated under the following conditions, and it was confirmed that the surface had lost its tackiness. Furthermore, the coating formed from the copper plate was peeled off, and FT-IR (Fourier transform infrared spectroscopy) analysis (Spectrum 100, manufactured by Perkin Elmer) confirmed that the hydrosilyl groups and vinyl groups had decreased, indicating that the hydrosilylation reaction had progressed.
[Ultraviolet light irradiation conditions]
Lamp: 80 W/cm high pressure mercury lamp Lamp height: 10 cm
Conveyor speed: 4.5 m/min
Accumulated light amount per pass: 990 mJ/ ^cm2
Atmosphere: Air Number of passes: 10

Example 2
[Preparation of photocurable composition and confirmation of photocurability]
A photocurable composition was prepared in the same manner as in Example 1(1) using the silsesquioxane derivative 2 obtained in Synthesis Example 2. The photocurable composition was subjected to photocuring in the same manner as in Example 1(2), and it was confirmed that a photohydrosilylation reaction proceeded to give a cured product.

<Examples 3 to 11>
[Preparation of photocurable composition and confirmation of photocurability]
Photocurable compositions were prepared in the same manner as in Example 1(1) using the silsesquioxane derivatives 3 to 11 obtained in Synthesis Examples 3 to 11. These were subjected to photocuring in the same manner as in Example 1(2) except for the following ultraviolet irradiation conditions, and it was confirmed that a photohydrosilylation reaction proceeded in all cases to give a cured product.
[Ultraviolet light irradiation conditions]
Lamp: 80 W/cm high pressure mercury lamp Lamp height: 10 cm
Conveyor speed: 10 m/min
Accumulated light amount per pass: 210 mJ/ ^cm2
Atmosphere: Air Number of passes: 30

Example 12
Heat resistance evaluation of cured product
A photohydrosilylation cured product was produced in the same manner as in Example 1(2) using the silsesquioxane derivative 1 obtained in Synthesis Example 1 and the photocurable composition prepared in Example 1(1), except that the substrate in Example 1(2) was replaced with a PET film. The resulting cured product was peeled off from the PET film and subjected to thermogravimetric differential thermal analysis (hereinafter referred to as TG/DTA) (TG/DTA6300 manufactured by Seiko Instruments Inc., in air, heating rate of 20°C/min) to determine the 5% weight loss temperature (hereinafter referred to as _Td5 ), which was 396°C.

<Examples 13 to 16>
[Evaluation of heat resistance of cured product]
The silsesquioxane derivatives 3, 4, 7 and 10 obtained in Synthesis Examples 3, 4, 7 and 10 were used to prepare photocurable compositions in Examples 3, 4, 7 and 10, and the TG/DTA of the cured products was measured in the same manner as in Example 12 to determine each _Td5 .

The T _d5 values determined in Examples 12 to 16 are summarized in Table 3.

<Example 17>
Measurement of the dielectric constant of the cured material
Using the silsesquioxane derivative 1 obtained in Synthesis Example 1, the photocurable composition prepared in Example 1(1) was poured into a mold made by cutting a hole measuring 40 mm × 40 mm in a 1 mm thick silicone rubber sheet, and the molded product was sandwiched between a PET film and a white glass plate, and a photohydrosilylation cured product was produced under the same UV irradiation conditions as in Example 1(2).
The resulting cured product was subjected to dielectric constant measurement (Agilent Technologies Impedance Analyzer 4294A) at room temperature (23° C.) and found to have a dielectric constant of 3.38 at 1 MHz. The dielectric constant at 1 MHz and the dielectric constants in other frequency bands are shown in Table 4.

<Example 18>
Measurement of the dielectric constant of the cured material
The photocurable composition prepared in Example 4 was used to measure the dielectric constant in the same manner as in Example 17, using Silsesquioxane 4 obtained in Synthesis Example 4. The dielectric constant at 1 MHz was 3.28. Table 4 shows the dielectric constant at 1 MHz and the dielectric constants in other frequency bands.

<Comparative Example 1>
0.3 g of 2-hydroxy-2-methylpropiophenone (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to 10 g of 3-acryloyloxypropylsilsesquioxane obtained in Reference Example 1, and the mixture was stirred and dissolved to prepare a photocurable composition. This was applied to a PET film with a bar coater to form a coating film with a thickness of about 10 μm. Then, ultraviolet irradiation was performed under the following conditions to produce a cured product.
[Ultraviolet light irradiation conditions]
Lamp: 80 W/cm high pressure mercury lamp Lamp height: 10 cm
Conveyor speed: 10 m/min Accumulated light amount per irradiation pass: 210 mJ/ ^cm2
Atmosphere: air Number of passes: 30 times T _d5 (in air) determined in the same manner as in Example 12 was 360°C.
The dielectric constant at 1 MHz was found to be 4.24 in the same manner as in Example 17. The dielectric constant at 1 MHz and the dielectric constants in other frequency bands are shown in Table 4.

<Comparative Example 2>
A cured product was prepared in the same manner as in Comparative Example 1, except that AC-SQ SI-20 of Reference Example 2 was used, and the T _d5 (in air) and dielectric constant of the cured product were measured. T _d5 (in air) was 340° C., and the dielectric constant at 1 MHz was 4.31. The dielectric constant at 1 MHz and the dielectric constants in other frequency bands are shown in Table 4.

The photohydrosilylation-curable composition of the present disclosure has good photocurability and is applicable to a wider range of substrates than known thermal hydrosilylation-curable compositions, enabling use in a variety of applications.
Furthermore, the _Td5 of the photohydrosilylation-cured product of the present disclosure is extremely high and has excellent heat resistance, compared to the cured products of photoradical curable compositions (Comparative Examples 1 and 2), which are representative examples of conventional photocurable silsesquioxane derivatives.
Furthermore, the photohydrosilylation-cured product of the present disclosure has a dielectric constant that is very low compared to the cured product of the photoradical curable composition (Comparative Examples 1 and 2), and has excellent insulating properties at all frequencies measured. In the wide frequency range measured from 1 kHz to 10 MHz, the photohydrosilylation-cured product of the present disclosure has a dielectric constant of 3.5 or less, and has high heat resistance and excellent insulating properties.

The photocurable composition of the present disclosure is useful for forming a heat-resistant film, and is a liquid composition that can be easily applied and filled into any shape. It can be cured at room temperature and can form a film having good properties such as water resistance, chemical resistance, stability, electrical insulation, and mechanical strength such as scratch resistance. Therefore, it can be used as a film or layer of articles or parts in a wide range of fields including electronics, optical functional materials, mobility, aerospace, and building materials. It can be used to form passivation films, resist films, interlayer insulating films, and various protective films in semiconductors, etc. The photocurable composition of the present disclosure and its cured product are useful in various fields where both high heat resistance and insulation properties are increasingly required in the future.

The disclosure of Japanese Patent Application No. 2020-106880, filed on June 22, 2020, is incorporated herein by reference in its entirety.
All publications, patent applications, and standards mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent application, or standard was specifically and individually indicated to be incorporated by reference.

Claims (11)

A photocurable composition comprising a silsesquioxane derivative represented by the following formula (1) and a hydrosilylation catalyst containing a transition metal:


[In formula (1),
R ¹ is an organic group having 2 to 12 carbon atoms and a hydrosilylation-reactive carbon-carbon unsaturated bond,
^R2 is at least one selected from the group consisting of an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, and an aralkyl group having 7 to 10 carbon atoms;
each of a plurality of R ^3's and R ^4's is independently at least one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aralkyl group having 7 to 10 carbon atoms, and an organic group having 2 to 12 carbon atoms and a hydrosilylation reactive carbon-carbon unsaturated bond;
A plurality of R ³ 's may be the same or different.
A plurality of R ⁴ 's may be the same or different.
u, v, w and x each independently represent 0 or a positive number, at least one of which is a positive number;
Each of y and z is independently 0 or a positive number;
0≦y/(u+v+w+x)≦2.0,
0≦z/(u+v+w+x)≦2.0,
However, when v=0 and w is a positive number , at least one of the multiple R ^3's and R ⁴ 's is a hydrogen atom, when w=0 and v is a positive number , at least one of the multiple R ^3's and R ^4's is an organic group having 2 to 12 carbon atoms and a carbon-carbon unsaturated bond capable of hydrosilylation, and when v=w=0, at least one of the multiple R ^3's and R ⁴ 's is a hydrogen atom, and at least one of the multiple R ^3's and R ^4's is an organic group having 2 to 12 carbon atoms and a carbon-carbon unsaturated bond capable of hydrosilylation . The photocurable composition according to claim 1, wherein the ratio of the number of hydrogen atoms bonded to silicon atoms to one organic group having a hydrosilylation-reactive carbon-carbon unsaturated bond present in the silsesquioxane derivative is 0.5 to 5.0. The photocurable composition according to claim 1 or 2, wherein the transition metal content is 0.1 to 30,000 ppm by weight per 100 parts by weight of the silsesquioxane derivative. The photocurable composition according to any one of claims 1 to 3, wherein the transition metal is a platinum group metal. The photocurable composition according to any one of claims 1 ^to 4, wherein the hydrosilylation catalyst containing a transition metal is at least one selected from the group consisting of β-diketonato platinum complexes, (η-cyclopentadienyl)trialkyl platinum complexes, (η-1,5-cyclooctadiene)diaryl platinum complexes, and dialkyl azodicarboxylate platinum complexes. The photocurable composition according to any one of claims 1 to 5, further comprising a heat resistance improver. A cured product obtained by curing the photocurable composition according to any one of claims 1 to 6. The cured product according to claim 7, having a relative dielectric constant of 4.0 or less at 1 MHz. The cured product according to claim 7 or 8, which has a 5% weight loss temperature in air in thermogravimetry of 300°C or higher. The cured product according to any one of claims 7 to 9 is an insulating film. A method for producing a cured product, comprising a step of curing the photocurable composition according to any one of claims 1 to 6 by irradiating it with ultraviolet light.