Crosslinkable cyclic carbonate-modified silicone composition and crosslinked cyclic carbonate-modified silicone elastomer produced therefrom

Abstract

To provide a crosslinkable silicone composition that enables formation of a silicone elastomer exhibiting a high dielectric constant and low elastic modulus.SOLUTION: A crosslinkable cyclic carbonate-modified silicone composition comprises: a linear or branched cyclic carbonate-modified silicone polymer (A) having a weight-average molecular weight of 2500 or more and containing structural units having a vinyl group and structural units having a cyclic carbonate group in a side chain; and a linear or branched cyclic carbonate-modified silicone polymer (B) having a weight-average molecular weight of 2500 or more and containing structural units having a hydrosilyl group and structural units having a cyclic carbonate group in a side chain; wherein, in the silicone polymer (A), a ratio of the branched structural units to the total of the linear and branched structural units is 0 to 30 mol%, and in the silicone polymer (B), a ratio of the branched structural units to the total of the linear and branched structural units is 0 to 30 mol%, and the crosslink density is 0.35 mmol / g or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a crosslinkable cyclic carbonate-modified silicone composition and a crosslinked cyclic carbonate-modified silicone elastomer using the same. [Background technology]

[0002] Silicone polymers are polymeric materials that have properties such as low elastic modulus, high electrical resistance, and high moisture resistance, and are useful as materials for forming dielectric layers in actuators and sensors. However, conventional silicone polymers do not necessarily have a sufficiently high dielectric constant. For this reason, studies have been conducted to improve the dielectric constant by introducing functional groups with high polarization, such as cyano groups, into the side chains of silicone polymers (for example, JP 2002-265788 A (Patent Document 1) and JP 2013-28724 A (Patent Document 2)).

[0003] Furthermore, Japanese Patent Laid-Open No. 2007-77052 (Patent Document 3) and Japanese Patent Laid-Open No. 2007-77075 (Patent Document 4) disclose cyclic carbonate-modified polysiloxanes. These cyclic carbonate-modified polysiloxanes have a small molecular weight and no crosslinking points, so it is difficult to form a crosslinked structure to obtain a silicone elastomer. Furthermore, it is difficult to obtain a high molecular weight cyclic carbonate-modified polysiloxane using the methods described in Patent Documents 3 and 4. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Publication No. 2002-265788 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-28724 [Patent Document 3] Japanese Patent Application Laid-Open No. 2007-77052 [Patent Document 4] Japanese Patent Application Laid-Open No. 2007-77075 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention was made in consideration of the problems associated with the prior art described above, and has as its object to provide a silicone elastomer having a high relative dielectric constant and a low elastic modulus, and a crosslinkable silicone composition capable of forming this silicone elastomer. [Means for solving the problem]

[0006] As a result of extensive research into achieving the above object, the present inventors discovered that by using a crosslinkable cyclic carbonate-modified silicone composition that contains a high molecular weight cyclic carbonate-modified silicone polymer having vinyl groups and a high molecular weight cyclic carbonate-modified silicone polymer having hydrosilyl groups, and that has a proportion of branched structures and a crosslinking density within specified ranges, it is possible to obtain a crosslinked cyclic carbonate-modified silicone elastomer with a high dielectric constant and a low elastic modulus, which led to the completion of the present invention.

[0007] That is, the present invention provides the following aspects. [1] A linear or branched cyclic carbonate-modified silicone polymer (A) having a weight average molecular weight of 2500 or more and having a structural unit containing a vinyl group and a structural unit containing a cyclic carbonate group in a side chain; a linear or branched cyclic carbonate-modified silicone polymer (B) having a weight average molecular weight of 2500 or more and having a structural unit containing a hydrosilyl group and a structural unit containing a cyclic carbonate group in a side chain; Contains In the silicone polymer (A), the proportion of branched-chain structural units relative to the total of linear-chain structural units and branched-chain structural units is 0 to 30 mol %, In the silicone polymer (B), the proportion of branched-chain structural units relative to the total of linear-chain structural units and branched-chain structural units is 0 to 30 mol %, A crosslinkable cyclic carbonate-modified silicone composition having a crosslink density of 0.35 mmol / g or greater. [2] The crosslinkable cyclic carbonate-modified silicone composition according to [1], wherein the silicone polymer (A) has a structural unit containing a vinyl group at least at the terminal. [3] The crosslinkable cyclic carbonate-modified silicone composition according to [1] or [2], wherein the silicone polymer (B) has a structural unit containing a hydrosilyl group at least at the terminal. [4] The silicone polymer (A) is represented by the following formula (a):

[0008] [ka]

[0009] [In the above formula, A represents a cyclic carbonate group, Z represents one of a divalent hydrocarbon group and a divalent hetero group, a plurality of Rs each independently represent a monovalent hydrocarbon group, a is 0.45 to 0.98, b is 0 to 0.50, c is 0 to 0.15, d is 0.01 to 0.20, and a+b+c+d=1] It is expressed as The silicone polymer (B) is represented by the following formula (b):

[0010] [ka]

[0011] [In the above formula, A represents a cyclic carbonate group, Z represents one of a divalent hydrocarbon group and a divalent hetero group, a plurality of Rs each independently represent a monovalent hydrocarbon group, e is 0.45 to 0.98, f is 0 to 0.45, g is 0 to 0.10, h is 0.01 to 0.15, and e+f+g+h=1] The crosslinkable cyclic carbonate-modified silicone composition according to any one of [1] to [3], wherein the crosslinkable cyclic carbonate-modified silicone composition is represented by the following formula: [5] A hydrosilylation reaction product of the crosslinkable cyclic carbonate-modified silicone composition according to any one of [1] to [4], A crosslinked cyclic carbonate-modified silicone elastomer in which a vinyl group of the silicone polymer (A) and a hydrosilyl group of the silicone polymer (B) form a covalent bond. [6] The crosslinked cyclic carbonate-modified silicone elastomer according to [5], wherein the hydrosilylation reaction product is a crosslinked product obtained by a platinum group catalyst. [7] The crosslinked cyclic carbonate-modified silicone elastomer according to [5] or [6], which has a crosslink density of 0.35 mmol / g or more.

[0012] Although the reason why the crosslinkable cyclic carbonate-modified silicone composition of the present invention produces a silicone elastomer with a high dielectric constant and a low modulus of elasticity is not entirely clear, the present inventors speculate as follows. Specifically, the crosslinkable cyclic carbonate-modified silicone composition of the present invention contains a high molecular weight cyclic carbonate-modified silicone polymer (A) having vinyl groups and a high molecular weight cyclic carbonate-modified silicone polymer (B) having hydrosilyl groups. When this crosslinkable cyclic carbonate-modified silicone composition is crosslinked, a crosslinked silicone elastomer having cyclic carbonate groups in its side chains is formed. Because cyclic carbonate groups are highly polarizable functional groups, it is speculated that the crosslinked silicone elastomer of the present invention has a high dielectric constant.

[0013] Furthermore, since the silicone polymer contained in the crosslinkable cyclic carbonate-modified silicone composition of the present invention has a flexible polysiloxane structure as the main chain skeleton and excellent mobility, it is presumed that the crosslinked cyclic carbonate-modified silicone elastomer obtained by crosslinking the crosslinkable cyclic carbonate-modified silicone composition of the present invention will be a crosslinked silicone elastomer with a low elastic modulus. In the crosslinked cyclic carbonate-modified silicone elastomer of the present invention, the vinyl groups of the cyclic carbonate-modified silicone polymer (A) and the hydrosilyl groups of the cyclic carbonate-modified silicone polymer (B) are bonded to each other in a manner satisfying the following formula:

[0014] [ka]

[0015] As shown in the figure, a covalent bond is formed by a hydrosilylation (hydrosilylation) reaction to form an alkyl silicone structure (crosslinked structure). Because this alkyl silicone structure is unlikely to impair electrical properties, it is presumed that when the cyclic carbonate-modified silicone polymer (A) and the cyclic carbonate-modified silicone polymer (B) are subjected to a hydrosilylation (hydrosilylation) reaction, the crosslinkable cyclic carbonate-modified silicone composition of the present invention will maintain a high dielectric constant due to the cyclic carbonate groups while the elastic modulus will be lowered by crosslinking, resulting in the crosslinked cyclic carbonate-modified silicone elastomer of the present invention. [Effects of the Invention]

[0016] According to the present invention, it is possible to obtain a silicone elastomer having a high relative dielectric constant and a low modulus of elasticity. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a graph showing the molecular weight distribution of the vinyl group-containing cyclic carbonate-modified silicone polymers obtained in Synthesis Example A1 and Comparative Synthesis Example A1. [Figure 2] 1 is a graph showing the molecular weight distribution of the vinyl group-containing cyclic carbonate-modified silicone polymers obtained in Synthesis Examples A2 to A5. [Figure 3] 1 is a graph showing the molecular weight distribution of the vinyl group-containing cyclic carbonate-modified silicone polymer obtained in Comparative Synthesis Example A2. [Figure 4] 1 is a graph showing the molecular weight distribution of the cyclic carbonate-modified silicone polymers having hydrosilyl groups obtained in Synthesis Example B1 and Comparative Synthesis Example B1. [Figure 5] 1 is a graph showing the molecular weight distribution of the cyclic carbonate-modified silicone polymer having hydrosilyl groups obtained in Comparative Synthesis Example B2. [Figure 6]1 is a graph showing the relationship between the crosslink density and the storage modulus of the crosslinked cyclic carbonate-modified silicone elastomers prepared in Examples 1 to 3. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention will be described in detail below based on preferred embodiments thereof.

[0019] [Crosslinkable Cyclic Carbonate-Modified Silicone Composition] First, the crosslinkable cyclic carbonate-modified silicone composition of the present invention will be described. The crosslinkable cyclic carbonate-modified silicone composition of the present invention contains a linear or branched cyclic carbonate-modified silicone polymer (A) having a weight average molecular weight of 2500 or more and having a vinyl group-containing structural unit and a cyclic carbonate group-containing structural unit in the side chain, and a linear or branched cyclic carbonate-modified silicone polymer (B) having a weight average molecular weight of 2500 or more and having a hydrosilyl group-containing structural unit and a cyclic carbonate group-containing structural unit in the side chain, wherein the proportion of the branched structural units relative to the total of the linear and branched structural units in the silicone polymer (A) is 0 to 30 mol%, and the proportion of the branched structural units relative to the total of the linear and branched structural units in the silicone polymer (B) is 0 to 30 mol%, and the crosslink density is 0.35 mmol / g or more.

[0020] (A) A high molecular weight cyclic carbonate-modified silicone polymer having a vinyl group The high molecular weight cyclic carbonate-modified silicone polymer (A) having a vinyl group used in the present invention is a linear or branched silicone polymer having a weight average molecular weight of 2500 or more and containing a structural unit containing a cyclic carbonate group and a structural unit containing a vinyl group.

[0021] The structural unit containing a cyclic carbonate group is a bifunctional or trifunctional siloxane unit having a cyclic carbonate group in a side chain. The cyclic carbonate group may be directly bonded to a silicon atom in the siloxane unit, but is preferably bonded via a divalent hydrocarbon group or a divalent hetero group. Examples of the divalent hydrocarbon group include an alkylene group having 1 to 10 carbon atoms or an arylene group having 6 to 10 carbon atoms, with an alkylene group having 1 to 5 carbon atoms being preferred, and an alkylene group having 1 to 3 carbon atoms being more preferred. Examples of the divalent hetero group include an alkyleneoxy group having 1 to 20 carbon atoms or an aryleneoxy group having 6 to 10 carbon atoms, with an alkyleneoxy group having 1 to 10 carbon atoms being preferred, an alkyleneoxy group having 1 to 5 carbon atoms being more preferred, and an alkyleneoxy group having 1 to 3 carbon atoms being even more preferred. The remaining organic substituents bonded to silicon atoms in the siloxane units include monovalent hydrocarbon groups, preferably alkyl groups having 1 to 5 carbon atoms, and more preferably alkyl groups having 1 to 3 carbon atoms. The proportion of such structural units containing cyclic carbonate groups is preferably 60 to 98 mol%, more preferably 70 to 90 mol%, and even more preferably 75 to 85 mol%, based on all structural units of the cyclic carbonate-modified silicone polymer (A).

[0022] The vinyl group-containing structural unit is a monofunctional to trifunctional siloxane unit having a vinyl group in a side chain. The vinyl group may be bonded to a silicon atom in the siloxane unit via a divalent hydrocarbon group or a divalent hetero group, but from the viewpoint of mechanical properties, it is preferably bonded directly. Examples of the divalent hydrocarbon group include an alkylene group having 1 to 10 carbon atoms or an arylene group having 6 to 10 carbon atoms, with an alkylene group having 1 to 5 carbon atoms being preferred, and an alkylene group having 1 to 3 carbon atoms being more preferred. Examples of the divalent hetero group include an alkyleneoxy group having 1 to 20 carbon atoms or an aryleneoxy group having 6 to 10 carbon atoms, with an alkyleneoxy group having 1 to 10 carbon atoms being preferred, an alkyleneoxy group having 1 to 5 carbon atoms being more preferred, and an alkyleneoxy group having 1 to 3 carbon atoms being even more preferred. The remaining organic substituents bonded to silicon atoms in the siloxane units include monovalent hydrocarbon groups, preferably alkyl groups having 1 to 5 carbon atoms, and more preferably alkyl groups having 1 to 3 carbon atoms. The vinyl group-containing structural units may be present either within the main chain of the cyclic carbonate-modified silicone polymer (A) or at the terminals, but are preferably present at least at the terminals. The proportion of such vinyl group-containing structural units present within the main chain of the cyclic carbonate-modified silicone polymer (A) is preferably 0 to 25 mol%, more preferably 3 to 20 mol%, and even more preferably 5 to 15 mol%, relative to the total structural units of the cyclic carbonate-modified silicone polymer (A). The proportion of terminal structural units is preferably 1 to 25 mol%, more preferably 5 to 20 mol%, and even more preferably 10 to 18 mol%.

[0023] Furthermore, the cyclic carbonate-modified silicone polymer (A) may contain other difunctional or trifunctional siloxane units in addition to the cyclic carbonate group-containing structural units and the vinyl group-containing structural units. Examples of other difunctional or trifunctional siloxane units include siloxane units in which one or two monovalent hydrocarbon groups are bonded to one silicon atom. The monovalent hydrocarbon groups are preferably each independently an alkyl group having 1 to 5 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms. Examples of such other difunctional or trifunctional siloxane units include dialkylsiloxane units such as dimethylsiloxane units and ethylmethylsiloxane units, and alkylsiloxane units such as methylsiloxane units and ethylsiloxane units. Furthermore, the proportion of such other difunctional or trifunctional siloxane units is preferably 0 to 30 mol %, more preferably 0 to 20 mol %, and even more preferably 0 to 10 mol %, relative to all constituent units of the cyclic carbonate-modified silicone polymer (A).

[0024] In the cyclic carbonate-modified silicone polymer (A), the proportion of branched-chain structural units relative to the total of linear structural units and branched-chain structural units is 0 to 30 mol%. If the proportion of branched-chain structural units exceeds the upper limit, gelation of the cyclic carbonate-modified silicone polymer (A) occurs, making it impossible to obtain a uniform crosslinked cyclic carbonate-modified silicone elastomer. Furthermore, from the viewpoint of suppressing gelation of the cyclic carbonate-modified silicone polymer (A), the proportion of branched-chain structural units is preferably 0 to 20 mol%, more preferably 0 to 10 mol%, and even more preferably 0 to 5 mol%.

[0025] Examples of such cyclic carbonate-modified silicone polymers (A) include those represented by the following formula (a):

[0026] [ka]

[0027] Examples include those represented by the following formula:

[0028] In the formula, A represents a cyclic carbonate group. The cyclic carbonate group is a ring structure formed by bonding a carbonate group and a divalent hydrocarbon group. Examples of the divalent hydrocarbon group include an alkylene group and an alkenylene group. The alkylene group preferably has 1 to 5 carbon atoms, more preferably 1 to 3 carbon atoms. The alkenylene group preferably has 2 to 5 carbon atoms, more preferably 2 to 3 carbon atoms. Examples of the cyclic carbonate group include a dioxetanone ring, a dioxolanone ring, and a dioxanone ring.

[0029] In the above formula, Z represents a divalent hydrocarbon group or a divalent hetero group. Examples of the divalent hydrocarbon group include an alkylene group having 1 to 10 carbon atoms or an arylene group having 6 to 10 carbon atoms, with an alkylene group having 1 to 5 carbon atoms being preferred, and an alkylene group having 1 to 3 carbon atoms being more preferred. Examples of the divalent hetero group include an alkyleneoxy group having 1 to 20 carbon atoms or an aryleneoxy group having 6 to 10 carbon atoms, with an alkyleneoxy group having 1 to 10 carbon atoms being preferred, an alkyleneoxy group having 1 to 5 carbon atoms being more preferred, and an alkyleneoxy group having 1 to 3 carbon atoms being even more preferred.

[0030] In the formula, each of the multiple R's independently represents a monovalent hydrocarbon group. The monovalent hydrocarbon group is preferably an alkyl group having 1 to 5 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms.

[0031] In the formula, a is 0.60 to 0.98, preferably 0.70 to 0.90, and more preferably 0.75 to 0.85. b is 0 to 0.30, preferably 0 to 0.20, and more preferably 0 to 0.10. c is 0 to 0.25, preferably 0.03 to 0.20, and more preferably 0.05 to 0.15. d is 0.01 to 0.25, preferably 0.05 to 0.20, and more preferably 0.10 to 0.18. In the formula (a), a+b+c+d=1.

[0032] The weight-average molecular weight of the cyclic carbonate-modified silicone polymer (A) must be 2,500 or more. If the weight-average molecular weight of the cyclic carbonate-modified silicone polymer (A) is less than the lower limit, the mechanical strength of the resulting crosslinked cyclic carbonate-modified silicone elastomer will decrease. From the viewpoint of improving the mechanical strength of the resulting crosslinked cyclic carbonate-modified silicone elastomer, the weight-average molecular weight of the cyclic carbonate-modified silicone polymer (A) is preferably 5,000 or more. There is no particular upper limit to the weight-average molecular weight of the cyclic carbonate-modified silicone polymer (A), but because a molecular weight that is too high may induce gelation, it is preferably 1,000,000 or less, and more preferably 100,000 or less.

[0033] Such a cyclic carbonate-modified silicone polymer (A) can be prepared by reacting silane monomers corresponding to each structural unit using a known method.

[0034] (B) A high molecular weight cyclic carbonate-modified silicone polymer having hydrosilyl groups. The high molecular weight cyclic carbonate-modified silicone polymer (B) having hydrosilyl groups used in the present invention is a linear or branched silicone polymer having a weight average molecular weight of 2500 or more and containing structural units containing cyclic carbonate groups and structural units containing hydrosilyl groups.

[0035] The structural unit containing a cyclic carbonate group is a bifunctional or trifunctional siloxane unit having a cyclic carbonate group in a side chain. The cyclic carbonate group may be directly bonded to a silicon atom in the siloxane unit, but is preferably bonded via a divalent hydrocarbon group or a divalent hetero group. Examples of the divalent hydrocarbon group include an alkylene group having 1 to 10 carbon atoms or an arylene group having 6 to 10 carbon atoms, with an alkylene group having 1 to 5 carbon atoms being preferred, and an alkylene group having 1 to 3 carbon atoms being more preferred. Examples of the divalent hetero group include an alkyleneoxy group having 1 to 20 carbon atoms or an aryleneoxy group having 6 to 10 carbon atoms, with an alkyleneoxy group having 1 to 10 carbon atoms being preferred, an alkyleneoxy group having 1 to 5 carbon atoms being more preferred, and an alkyleneoxy group having 1 to 3 carbon atoms being even more preferred. The remaining organic substituents bonded to silicon atoms in the siloxane units include monovalent hydrocarbon groups, preferably alkyl groups having 1 to 5 carbon atoms, and more preferably alkyl groups having 1 to 3 carbon atoms. The proportion of such structural units containing cyclic carbonate groups is preferably 60 to 98 mol%, more preferably 70 to 90 mol%, and even more preferably 75 to 85 mol%, based on all structural units of the cyclic carbonate-modified silicone polymer (B).

[0036] The hydrosilyl group-containing structural unit has a structure (hydrosilyl group) in which a hydrogen atom is bonded to a silicon atom in a monofunctional to trifunctional siloxane unit. The remaining organic substituents bonded to the silicon atom in the siloxane unit include monovalent hydrocarbon groups, preferably alkyl groups having 1 to 5 carbon atoms, and more preferably alkyl groups having 1 to 3 carbon atoms. The hydrosilyl group-containing structural unit may be present either within the main chain of the cyclic carbonate-modified silicone polymer (B) or at a terminal, but is preferably present at least at a terminal. The proportion of such hydrosilyl group-containing structural units present within the main chain of the cyclic carbonate-modified silicone polymer (B) is preferably 0 to 35 mol %, more preferably 10 to 30 mol %, and even more preferably 15 to 25 mol %, relative to the total structural units of the cyclic carbonate-modified silicone polymer (B). The proportion of terminal structural units is preferably 1 to 15 mol %, more preferably 2 to 10 mol %.

[0037] Furthermore, the cyclic carbonate-modified silicone polymer (B) may contain other difunctional or trifunctional siloxane units in addition to the cyclic carbonate group-containing structural units and the hydrosilyl group-containing structural units. Examples of other difunctional or trifunctional siloxane units include siloxane units in which one or two monovalent hydrocarbon groups are bonded to one silicon atom. The monovalent hydrocarbon groups are preferably each independently an alkyl group having 1 to 5 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms. Examples of such other difunctional or trifunctional siloxane units include dialkylsiloxane units such as dimethylsiloxane units and ethylmethylsiloxane units, and alkylsiloxane units such as methylsiloxane units and ethylsiloxane units. Furthermore, the proportion of such other difunctional or trifunctional siloxane units is preferably 0 to 30 mol %, more preferably 0 to 20 mol %, and even more preferably 0 to 10 mol %, relative to all constituent units of the cyclic carbonate-modified silicone polymer (B).

[0038] In the cyclic carbonate-modified silicone polymer (B), the proportion of branched-chain structural units relative to the total of linear structural units and branched-chain structural units is 0 to 30 mol%. If the proportion of branched-chain structural units exceeds the upper limit, gelation of the cyclic carbonate-modified silicone polymer (B) occurs, making it impossible to obtain a uniform crosslinked cyclic carbonate-modified silicone elastomer. Furthermore, from the viewpoint of suppressing gelation of the cyclic carbonate-modified silicone polymer (B), the proportion of branched-chain structural units is preferably 0 to 20 mol%, more preferably 0 to 10 mol%, and even more preferably 0 to 5 mol%.

[0039] Examples of such cyclic carbonate-modified silicone polymers (B) include those represented by the following formula (b):

[0040] [ka]

[0041] Examples include those represented by the following formula:

[0042] In the formula, A represents a cyclic carbonate group. The cyclic carbonate group is a ring structure formed by bonding a carbonate group and a divalent hydrocarbon group. Examples of the divalent hydrocarbon group include an alkylene group and an alkenylene group. The alkylene group preferably has 1 to 5 carbon atoms, more preferably 1 to 3 carbon atoms. The alkenylene group preferably has 2 to 5 carbon atoms, more preferably 2 to 3 carbon atoms. Examples of the cyclic carbonate group include a dioxetanone ring, a dioxolanone ring, and a dioxanone ring.

[0043] In the above formula, Z represents a divalent hydrocarbon group or a divalent hetero group. Examples of the divalent hydrocarbon group include an alkylene group having 1 to 10 carbon atoms or an arylene group having 6 to 10 carbon atoms, with an alkylene group having 1 to 5 carbon atoms being preferred, and an alkylene group having 1 to 3 carbon atoms being more preferred. Examples of the divalent hetero group include an alkyleneoxy group having 1 to 20 carbon atoms or an aryleneoxy group having 6 to 10 carbon atoms, with an alkyleneoxy group having 1 to 10 carbon atoms being preferred, an alkyleneoxy group having 1 to 5 carbon atoms being more preferred, and an alkyleneoxy group having 1 to 3 carbon atoms being even more preferred.

[0044] In the formula, each of the multiple R's independently represents a monovalent hydrocarbon group. The monovalent hydrocarbon group is preferably an alkyl group having 1 to 5 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms.

[0045] In the formula (b), e is 0.60 to 0.98, preferably 0.70 to 0.90, and more preferably 0.75 to 0.85. f is 0 to 0.30, preferably 0 to 0.20, and more preferably 0 to 0.10. g is 0 to 0.35, preferably 0.10 to 0.30, and even more preferably 0.15 to 0.25. h is 0.01 to 0.15, and preferably 0.02 to 0.10. In the formula (b), e+f+g+h=1.

[0046] The weight-average molecular weight of the cyclic carbonate-modified silicone polymer (B) must be 2,500 or more. If the weight-average molecular weight of the cyclic carbonate-modified silicone polymer (B) is less than the lower limit, the mechanical strength of the resulting crosslinked cyclic carbonate-modified silicone elastomer will decrease. From the viewpoint of improving the mechanical strength of the resulting crosslinked cyclic carbonate-modified silicone elastomer, the weight-average molecular weight of the cyclic carbonate-modified silicone polymer (B) is preferably 5,000 or more. There is no particular upper limit to the weight-average molecular weight of the cyclic carbonate-modified silicone polymer (B), but because a molecular weight that is too high may induce gelation, it is preferably 1,000,000 or less, and more preferably 100,000 or less.

[0047] Such a cyclic carbonate-modified silicone polymer (B) can be prepared by reacting silane monomers corresponding to each structural unit using a known method.

[0048] (Crosslinkable Cyclic Carbonate-Modified Silicone Composition) The crosslinkable cyclic carbonate-modified silicone composition of the present invention contains the high molecular weight cyclic carbonate-modified silicone polymer (A) having a vinyl group and the high molecular weight cyclic carbonate-modified silicone polymer (B) having a hydrosilyl group. In the crosslinkable cyclic carbonate-modified silicone composition, the mass ratio (A / B) of the cyclic carbonate-modified silicone polymer (A) to the cyclic carbonate-modified silicone polymer (B) is preferably 50 / 1 to 1 / 50, more preferably 20 / 1 to 1 / 20, and even more preferably 5 / 1 to 1 / 5. If the mass ratio (A / B) is less than the lower limit, the effect of weighing error on the crosslink density becomes significant, making it difficult to adjust the molar ratio of crosslinking groups. On the other hand, if the mass ratio (A / B) exceeds the upper limit, the effect of weighing error on the crosslink density becomes significant, making it difficult to adjust the molar ratio of crosslinking groups. At the same time, decomposition of the hydrosilyl groups in the cyclic carbonate-modified silicone polymer (B) tends to make it difficult to balance the mass ratio with the vinyl groups.

[0049] The crosslinkable cyclic carbonate-modified silicone composition of the present invention has a crosslink density of 0.35 mmol / g or more. If the crosslink density is below the lower limit, the mechanical strength of the resulting crosslinked cyclic carbonate-modified silicone elastomer will decrease. From the viewpoints of improving the mechanical strength of the resulting crosslinked cyclic carbonate-modified silicone elastomer and preventing the density of crosslinking groups from becoming too low, making it difficult to obtain a crosslinked elastomer, the crosslink density of the crosslinkable cyclic carbonate-modified silicone composition is preferably 0.40 mmol / g or more, more preferably 0.50 mmol / g or more. There is no particular upper limit to the crosslink density of the crosslinkable cyclic carbonate-modified silicone composition, but from the viewpoint of preventing a decrease in the cyclic carbonate content, it is preferably 20 mmol / g or less, more preferably 5 mmol / g or less, and even more preferably 3 mmol / g or less.

[0050] The crosslinkable cyclic carbonate-modified silicone composition of the present invention may also contain a solvent, such as acetone, xylene, acetonitrile, alcohol, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), halogenated solvents, dioxane, and methyl ethyl ketone (MEK).

[0051] Furthermore, the crosslinkable cyclic carbonate-modified silicone composition of the present invention may contain a crosslinking catalyst. Examples of the crosslinking catalyst include platinum group catalysts such as platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex. By heating the crosslinkable cyclic carbonate-modified silicone composition containing such a crosslinking catalyst, the cyclic carbonate-modified silicone polymer (A) and the cyclic carbonate-modified silicone polymer (B) are thermally cured to produce the crosslinked cyclic carbonate-modified silicone elastomer of the present invention.

[0052] The crosslinkable cyclic carbonate-modified silicone composition of the present invention contains two types of cyclic carbonate-modified silicone polymers with the same or similar basic skeletons, and therefore can be easily mixed uniformly to easily form a uniform crosslinked product (crosslinked cyclic carbonate-modified silicone elastomer).

[0053] [Crosslinked cyclic carbonate-modified silicone elastomer] Next, the crosslinked cyclic carbonate-modified silicone elastomer of the present invention will be described. The crosslinked cyclic carbonate-modified silicone elastomer of the present invention is a hydrosilylation reaction product of the crosslinkable cyclic carbonate-modified silicone composition of the present invention. This hydrosilylation reaction product is preferably a product (crosslinked product) obtained by crosslinking the cyclic carbonate-modified silicone polymer (A) and the cyclic carbonate-modified silicone polymer (B) using the crosslinking catalyst (preferably a platinum group catalyst). This crosslinked product has a crosslinked structure formed by covalent bonding between the vinyl groups of the cyclic carbonate-modified silicone polymer (A) and the hydrosilyl groups of the cyclic carbonate-modified silicone polymer (B) through the action of the crosslinking catalyst.

[0054] The crosslinked cyclic carbonate-modified silicone elastomer of the present invention preferably has a crosslink density of 0.35 mmol / g or more. If the crosslink density is below the lower limit, the mechanical strength of the crosslinked cyclic carbonate-modified silicone elastomer decreases. From the viewpoint of improving the mechanical strength of the crosslinked cyclic carbonate-modified silicone elastomer, the crosslink density is preferably 0.40 mmol / g or more, and more preferably 0.50 mmol / g or more. There is no particular upper limit to the crosslink density, but from the viewpoint that an excessive increase in crosslinking groups reduces the carbonate content and also causes a loss of flexibility in the elastomer, it is preferably 10 mmol / g or less, more preferably 5 mmol / g or less, and even more preferably 3 mmol / g or less.

[0055] In the crosslinked cyclic carbonate-modified silicone elastomer of the present invention, since the polysiloxane has a glass transition temperature lower than room temperature, the polysiloxane structure, which is the main chain skeleton of the silicone, has high mobility at room temperature, and there is no factor that inhibits the orientation of the functional groups by an electric field, so it is thought that large orientation polarization can be obtained.In addition, since the polysiloxane structure, which is the main chain skeleton of the silicone, has high electrical insulation properties, it is thought that even if a cyclic carbonate group with high polarization is introduced into the side chain, it will show high electrical resistance.

[0056] Furthermore, in the crosslinked cyclic carbonate-modified silicone elastomer of the present invention, as described above, an alkyl silicone structure is formed as a crosslinked structure by the hydrosilylation reaction, making it possible to crosslink the crosslinkable cyclic carbonate-modified silicone composition without forming a crosslinked structure that would reduce insulating properties. As a result, it is believed that the resulting crosslinked cyclic carbonate-modified silicone elastomer exhibits high electrical resistance. [Example]

[0057] The present invention will be described in more detail below based on examples and comparative examples, but the present invention is not limited to the following examples.

[0058] (Synthesis Example A1) <Synthesis of high molecular weight cyclic carbonate-modified linear silicone polymers containing vinyl groups> A Schlenk flask was charged with 0.8 g (3.6 mmol) of 4-[2-(dimethoxymethylsilyl)ethyl]-1,3-dioxolan-2-one, 109 mg (0.91 mmol) of dimethoxydimethylsilane, 31 μL (0.19 mmol) of dimethylethoxyvinylsilane, and 0.75 mL of dimethoxyethane, and the resulting mixture was cooled to −10° C. for 10 minutes under a nitrogen atmosphere. To this solution, 105 μL of a 1.4 M aqueous sulfuric acid solution was added, and the mixture was stirred at −10° C. for 30 minutes and then at room temperature for 1.5 hours to obtain the compound of the following formula:

[0059] [ka]

[0060] The reaction represented by the formula (1) was carried out. The resulting reaction solution was stirred at room temperature and dehydrated under reduced pressure using a rotary pump for 3 hours. The resulting reaction product was dissolved in 3 ml of acetonitrile and then reprecipitated using 25 ml of ion-exchanged water. The resulting precipitate was dried in vacuo to yield 0.298 g of a viscous oily vinyl-containing cyclic carbonate-modified linear silicone polymer.

[0061] 5 mg of the obtained silicone polymer was dissolved in 1.5 ml of acetone and filtered through a 0.2 μm pore size filter. The solution was then subjected to gel permeation chromatography (GPC, solvent: acetone, column: Shodex α-M, detector: differential refractometer) to determine the molecular weight distribution, number average molecular weight (Mn), and weight average molecular weight (Mw) of the silicone polymer in terms of polymethyl methacrylate (PMMA). These results are shown in Figure 1 and Table 1.

[0062] Furthermore, for the obtained silicone polymer, the proportions of structural units containing cyclic carbonate groups, structural units containing methyl groups, structural units containing non-terminal vinyl groups, and structural units containing terminal vinyl groups were determined from the amounts of raw material monomers charged. 1 The vinyl group equivalent weight was determined by H-NMR measurement, and the results are shown in Table 1.

[0063] (Synthesis example A2) <Synthesis of high molecular weight cyclic carbonate-modified linear silicone polymers containing vinyl groups> A compound represented by the following formula: was obtained in the same manner as in Synthesis Example A1, except that 2.0 g (9.3 mmol) of 4-[2-(dimethoxymethylsilyl)ethyl]-1,3-dioxolan-2-one, 54 mg (0.45 mmol) of dimethoxydimethylsilane, 60 mg (0.45 mmol) of dimethoxymethylvinylsilane, and 270 μL (1.8 mmol) of dimethylethoxyvinylsilane were used, the amount of dimethoxyethane was changed to 2 mL, the amount of aqueous sulfuric acid solution was changed to 580 μL, and the stirring time during the reaction was changed to 2 hours.

[0064] [ka]

[0065] The reaction represented by the formula (1) was carried out. The resulting reaction solution was stirred at room temperature and dehydrated under reduced pressure using a rotary pump for 2 hours. The resulting reaction product was dissolved in 6 ml of acetonitrile and reprecipitated using 30 ml of 0.67 M phosphate buffer (pH 6.0). The resulting precipitate was then dissolved in 6 ml of acetonitrile and reprecipitated using 30 ml of water. This acetonitrile-water reprecipitation process was repeated a total of three times, after which the resulting precipitate was again dissolved in 6 ml of acetonitrile and reprecipitated using 30 ml of diethyl ether. The resulting precipitate was dried in vacuo to obtain 0.725 g of a viscous oily vinyl-containing cyclic carbonate-modified linear silicone polymer.

[0066] The resulting silicone polymer was analyzed in the same manner as in Synthesis Example A1 to determine its PMMA-equivalent molecular weight distribution, number-average molecular weight (Mn), weight-average molecular weight (Mw), and the proportions of structural units containing cyclic carbonate groups, structural units containing methyl groups, structural units containing non-terminal vinyl groups, and structural units containing terminal vinyl groups, as well as its vinyl equivalent. The results are shown in Figure 2 and Table 1.

[0067] (Synthesis example A3) <Synthesis of high molecular weight cyclic carbonate-modified linear silicone polymers containing vinyl groups> A compound of the following formula:

[0068] [ka]

[0069] The reaction represented by the formula (1) was carried out. The resulting reaction solution was stirred at room temperature and dehydrated under reduced pressure using a rotary pump for 10 hours. The resulting reaction product was dissolved in 6 ml of acetonitrile and then reprecipitated using 30 ml of diethyl ether. This reprecipitation process using acetonitrile-diethyl ether was repeated a total of four times, and the resulting precipitate was then dried in vacuo to yield 0.896 g of a viscous oily vinyl-containing cyclic carbonate-modified linear silicone polymer.

[0070] The resulting silicone polymer was analyzed in the same manner as in Synthesis Example A1 to determine its PMMA-equivalent molecular weight distribution, number-average molecular weight (Mn), weight-average molecular weight (Mw), and the proportions of structural units containing cyclic carbonate groups, structural units containing methyl groups, structural units containing non-terminal vinyl groups, and structural units containing terminal vinyl groups, as well as its vinyl equivalent. The results are shown in Figure 2 and Table 1.

[0071] (Synthesis example A4) <Synthesis of high molecular weight cyclic carbonate-modified linear silicone polymers containing vinyl groups> A compound of the following formula:

[0072] [ka]

[0073] The reaction represented by the formula (1) was carried out. The resulting reaction solution was stirred at room temperature and dehydrated under reduced pressure using a rotary pump for 3.5 hours. The resulting reaction product was dissolved in 3 ml of acetonitrile and then reprecipitated using 20 ml of diethyl ether. This reprecipitation process using acetonitrile-diethyl ether was repeated a total of four times, and the resulting precipitate was then dried in vacuo to yield 0.466 g of a viscous oily vinyl-containing cyclic carbonate-modified linear silicone polymer.

[0074] The resulting silicone polymer was analyzed in the same manner as in Synthesis Example A1 to determine its PMMA-equivalent molecular weight distribution, number-average molecular weight (Mn), weight-average molecular weight (Mw), and the proportions of structural units containing cyclic carbonate groups, structural units containing methyl groups, structural units containing non-terminal vinyl groups, and structural units containing terminal vinyl groups, as well as its vinyl equivalent. The results are shown in Figure 2 and Table 1.

[0075] (Synthesis example A5) <Synthesis of high molecular weight cyclic carbonate-modified linear silicone polymers containing vinyl groups> A compound of the following formula:

[0076] [ka]

[0077] The reaction represented by the formula (1) was carried out. The resulting reaction solution was stirred at room temperature and dehydrated under reduced pressure using a rotary pump for 2 hours. The resulting reaction product was dissolved in 6 ml of acetonitrile and reprecipitated using 20 ml of 0.67 M phosphate buffer (pH 6.0). The resulting precipitate was then dissolved in 6 ml of acetonitrile and reprecipitated using 30 ml of water. This acetonitrile-water reprecipitation process was repeated a total of three times, after which the resulting precipitate was again dissolved in 6 ml of acetonitrile and reprecipitated using 30 ml of diethyl ether. The resulting precipitate was dried in vacuo to obtain 0.663 g of a viscous oily vinyl-containing cyclic carbonate-modified linear silicone polymer.

[0078] The resulting silicone polymer was analyzed in the same manner as in Synthesis Example A1 to determine its PMMA-equivalent molecular weight distribution, number-average molecular weight (Mn), weight-average molecular weight (Mw), and the proportions of structural units containing cyclic carbonate groups, structural units containing methyl groups, structural units containing non-terminal vinyl groups, and structural units containing terminal vinyl groups, as well as its vinyl equivalent. The results are shown in Figure 2 and Table 1.

[0079] (Synthesis example A6) <Synthesis of high molecular weight cyclic carbonate-modified branched silicone polymers containing vinyl groups> A compound of the following formula:

[0080] [ka]

[0081] The reaction represented by the formula (1) was carried out. The resulting reaction solution was stirred at room temperature and dehydrated under reduced pressure using a rotary pump for 10 hours. The resulting reaction product was dissolved in 4 ml of acetonitrile and then reprecipitated using 20 ml of diethyl ether. This reprecipitation process using acetonitrile-diethyl ether was repeated a total of four times, and the resulting precipitate was then dried in vacuo to yield 0.277 g of a viscous oily vinyl-containing cyclic carbonate-modified branched-chain silicone polymer.

[0082] The resulting silicone polymer was subjected to the same procedures as in Synthesis Example A1 to determine its PMMA-equivalent number-average molecular weight (Mn) and weight-average molecular weight (Mw), as well as the proportions of structural units containing cyclic carbonate groups, structural units containing methyl groups, structural units containing non-terminal vinyl groups, and structural units containing terminal vinyl groups, and the vinyl group equivalent. The results are shown in Table 1.

[0083] (Comparative Synthesis Example A1) <Synthesis of low molecular weight cyclic carbonate-modified linear silicone polymers containing vinyl groups> A Schlenk flask was charged with 0.38 g (1.7 mmol) of 4-[2-(dimethoxymethylsilyl)ethyl]-1,3-dioxolan-2-one, 51 mg (0.43 mmol) of dimethoxydimethylsilane, and 1 ml of dimethoxyethane, and the resulting mixture was cooled to −10° C. for 10 minutes under a nitrogen atmosphere. 290 μL of 1.4 M aqueous sulfuric acid solution was added to the solution, and the mixture was stirred at −10° C. for 30 minutes and then at room temperature for 1.5 hours. 15 μL (0.11 mmol) of dimethylethoxyvinylsilane was then added, and the mixture was stirred at room temperature for 2.5 hours to obtain the compound of the following formula:

[0084] [ka]

[0085] The reaction represented by the formula (1) was carried out. The resulting reaction solution was neutralized with aqueous ammonia, and 7 ml of ethyl acetate was added to extract the reaction product into an organic phase. The mixture was centrifuged at 4800 rpm for 10 minutes to remove the aqueous phase. 3 ml of water was added to the resulting organic phase, and the organic phase was washed with water. The mixture was centrifuged at 4800 rpm for 10 minutes to remove the aqueous phase. This water washing process was repeated three times, and then the solvent was removed using a rotary evaporator. The resulting oily substance was dried in vacuo to yield 0.321 g of a viscous oily linear silicone polymer having vinyl groups and cyclic carbonate groups.

[0086] The resulting silicone polymer was analyzed in the same manner as in Synthesis Example A1 to determine its PMMA-equivalent molecular weight distribution, number-average molecular weight (Mn), weight-average molecular weight (Mw), and the proportions of structural units containing cyclic carbonate groups, structural units containing methyl groups, structural units containing non-terminal vinyl groups, and structural units containing terminal vinyl groups, as well as its vinyl equivalent. The results are shown in Figure 1 and Table 1.

[0087] (Comparative synthesis example A2) <Synthesis of low molecular weight cyclic carbonate-modified linear silicone polymers containing vinyl groups> A Schlenk flask was charged with 940 mg (4.3 mmol) of 4-[2-(dimethoxymethylsilyl)ethyl]-1,3-dioxolan-2-one, 178 mg (1.5 mmol) of dimethoxydimethylsilane, 69 mg (0.64 mmol) of dimethoxymethylvinylsilane, and 1 ml of isopropanol, and the resulting mixture was cooled to -15°C for 10 minutes under a nitrogen atmosphere. To this solution, 290 µL of 1.4 M aqueous sulfuric acid solution was added, and the mixture was stirred at -15°C for 30 minutes and then at room temperature for 2 hours. Further, under ice cooling, 300 µL (2.0 mmol) of dimethylethoxyvinylsilane was added, and the mixture was stirred at room temperature for 2 hours to obtain the compound of the following formula:

[0088] [ka]

[0089] The reaction represented by the following formula was then carried out. The procedure was the same as in Comparative Synthesis Example A1, except that 1 ml of 3 M sodium acetate buffer (pH 5.8) was used instead of the aqueous ammonia solution and washing with water was carried out a total of four times, yielding 903 mg of a viscous oily vinyl-containing cyclic carbonate-modified linear silicone polymer.

[0090] The molecular weight distribution, number average molecular weight (Mn), and weight average molecular weight (Mw) of the resulting silicone polymer, calculated as PMMA, were determined in the same manner as in Synthesis Example A1, except that chloroform was used as the solvent. The proportions of structural units containing cyclic carbonate groups, structural units containing methyl groups, structural units containing non-terminal vinyl groups, and structural units containing terminal vinyl groups, as well as the vinyl group equivalent, were also determined for the resulting silicone polymer in the same manner as in Synthesis Example A1. These results are shown in Figure 3 and Table 1.

[0091] (Comparative synthesis example A3) <Synthesis of high molecular weight cyclic carbonate-modified branched silicone polymers containing vinyl groups> A compound of the following formula:

[0092] [ka]

[0093] The reaction represented by the formula (1) was carried out. The resulting reaction solution was stirred at room temperature and dehydrated under reduced pressure using a rotary pump for 10 hours. The resulting reaction product was dissolved in 6 ml of acetonitrile and reprecipitated using 20 ml of 0.67 M phosphate buffer (pH 6.0). The resulting precipitate was then dissolved in 6 ml of acetonitrile and reprecipitated using 30 ml of water. This reprecipitation process using acetonitrile and water was repeated a total of three times, after which the resulting precipitate was again dissolved in 6 ml of acetonitrile and further reprecipitated using 30 ml of ethyl ether. This reprecipitation process using acetonitrile and diethyl ether was repeated a total of two times, after which the resulting precipitate was dried under vacuum; however, the precipitate gelled and was insoluble in acetonitrile.

[0094] [Table 1]

[0095] As shown in Table 1, it was confirmed that vacuum dehydration increases the weight average molecular weight (Mw) of the cyclic carbonate-modified linear or branched silicone polymer having a vinyl group-containing structural unit to 2500 or more.

[0096] Furthermore, it was confirmed that gelation and insolubilization of the silicone polymer can be suppressed by adjusting the proportion of tri- or higher functional monomers among the raw material monomers to 30 mol% or less and then adjusting the proportion of branched structural units to 30 mol% or less relative to the total of linear structural units and branched structural units in the resulting cyclic carbonate-modified silicone polymer having structural units containing vinyl groups.

[0097] (Synthesis Example B1) <Synthesis of High Molecular Weight Cyclic Carbonate-Modified Linear Silicone Polymers with Hydrosilyl Groups> A Schlenk flask was charged with 5 g (22.7 mmol) of 4-[2-(dimethoxymethylsilyl)ethyl]-1,3-dioxolan-2-one, 0.60 mg (5.7 mmol) of dimethoxy(methyl)silane, 163 μL (1.2 mmol) of dimethylethoxysilane, and 6.3 mL of dimethoxyethane, and the resulting mixture was cooled to −10° C. for 10 minutes under a nitrogen atmosphere. To this solution, 1.8 mL of a 1.4 M aqueous sulfuric acid solution was added, and the mixture was stirred at −10° C. for 30 minutes and then at room temperature for 2 hours to obtain the compound of the following formula:

[0098] [ka]

[0099] The reaction represented by the formula (1) was carried out. The resulting reaction solution was stirred at room temperature and dehydrated under reduced pressure using a rotary pump for 2 hours. The resulting reaction product was dissolved in 15 ml of acetonitrile and reprecipitated using 75 ml of 0.67 M phosphate buffer (pH 6.0). The resulting precipitate was then dissolved in 15 ml of acetonitrile and reprecipitated using 75 ml of water. This reprecipitation process using acetonitrile and water was repeated a total of four times, after which the resulting precipitate was again dissolved in 6 ml of acetonitrile and further reprecipitated using 30 ml of diethyl ether. This reprecipitation process using acetonitrile and diethyl ether was repeated a total of 24 times, after which the resulting precipitate was vacuum dried to obtain 2.73 g of a viscous oily cyclic carbonate-modified linear silicone polymer having hydrosilyl groups.

[0100] 5 mg of the obtained silicone polymer was dissolved in 1.5 ml of acetone and filtered through a 0.2 μm pore size filter. The solution was then subjected to gel permeation chromatography (GPC, solvent: acetone, column: Shodex α-M, detector: differential refractometer) to determine the molecular weight distribution, number average molecular weight (Mn), and weight average molecular weight (Mw) of the silicone polymer in terms of polymethyl methacrylate (PMMA). These results are shown in Figure 4 and Table 2.

[0101] Furthermore, for the obtained silicone polymer, the proportions of structural units containing cyclic carbonate groups, structural units containing methyl groups, structural units containing non-terminal hydrosilyl groups, and structural units containing terminal hydrosilyl groups were determined from the amounts of raw material monomers charged. 1 The hydrosilyl group equivalent weight was determined by H-NMR measurement, and the results are shown in Table 2.

[0102] (Comparative Synthesis Example B1) <Synthesis of low molecular weight cyclic carbonate-modified linear silicone polymers with hydrosilyl groups> A Schlenk flask was charged with 5 g (22.7 mmol) of 4-[2-(dimethoxymethylsilyl)ethyl]-1,3-dioxolan-2-one, 0.60 g (5.7 mmol) of dimethoxy(methyl)silane, 5 g of isopropanol, and 6.3 ml of dimethoxyethane, and the resulting mixture was cooled to −10° C. for 10 minutes under a nitrogen atmosphere. To this solution, 1.4 ml of a 1.4 M aqueous sulfuric acid solution was added, and the mixture was stirred at −10° C. for 30 minutes and then at 42.5° C. for 2 hours. 780 μL (5.7 mmol) of dimethylethoxysilane was then added, and the mixture was stirred at room temperature for 1.5 hours to give the compound represented by the following formula:

[0103] [ka]

[0104] The reaction represented by the formula (1) was carried out. The resulting reaction solution was neutralized with aqueous ammonia, and 15 ml of ethyl acetate was added to extract the reaction product into an organic phase. The mixture was centrifuged at 4800 rpm for 10 minutes to remove the aqueous phase. 5 ml of water was added to the resulting organic phase, and the organic phase was washed with water. The mixture was centrifuged at 4800 rpm for 10 minutes to remove the aqueous phase. This water washing process was repeated a total of four times, and then the solvent was distilled off using a rotary evaporator. The resulting oily substance was dried in vacuo to obtain 2.73 g of a viscous oily cyclic carbonate-modified linear silicone polymer having hydrosilyl groups.

[0105] The obtained silicone polymer was subjected to the same procedures as in Synthesis Example B1, except that chloroform was used as the solvent, to determine the polystyrene-equivalent molecular weight distribution, number-average molecular weight (Mn), weight-average molecular weight (Mw), the proportions of structural units containing cyclic carbonate groups, structural units containing methyl groups, structural units containing non-terminal hydrosilyl groups, and structural units containing terminal hydrosilyl groups, and the hydrosilyl group equivalent. These results are shown in Figure 4 and Table 2.

[0106] (Comparative synthesis example B2) <Synthesis of low molecular weight cyclic carbonate-modified linear silicone polymers with hydrosilyl groups> A Schlenk flask was charged with 950 mg (4.3 mmol) of 4-[2-(dimethoxymethylsilyl)ethyl]-1,3-dioxolan-2-one, 181 mg (1.5 mmol) of dimethoxydimethylsilane, 69 mg (0.65 mmol) of dimethoxy(methyl)silane, and 1 ml of isopropanol, and the resulting mixture was cooled to -15°C for 10 minutes under a nitrogen atmosphere. To this solution, 290 μL of 1.4 M aqueous sulfuric acid solution was added, and the mixture was stirred at -15°C for 30 minutes and then at room temperature for 2 hours. Further, 300 μL (2.2 mmol) of dimethoxy(methyl)silane was added under ice cooling, and the mixture was stirred at room temperature for 2 hours to obtain the compound of the following formula:

[0107] [ka]

[0108] The reaction represented by the following formula was then carried out. The procedure was then repeated as in Comparative Synthesis Example B1, except that 1 ml of a 3 M sodium acetate buffer solution (pH 5.8) was used instead of the aqueous ammonia solution, the amount of ethyl acetate was changed to 7 ml, and the amount of water was changed to 3 ml, yielding 923 mg of a viscous oily cyclic carbonate-modified linear silicone polymer having hydrosilyl groups.

[0109] The molecular weight distribution, number average molecular weight (Mn), and weight average molecular weight (Mw) of the resulting silicone polymer, calculated as PMMA, were determined in the same manner as in Synthesis Example B1, except that chloroform was used as the solvent. The proportions of structural units containing cyclic carbonate groups, structural units containing methyl groups, structural units containing non-terminal hydrosilyl groups, and structural units containing terminal hydrosilyl groups, as well as the hydrosilyl group equivalent, were also determined in the same manner as in Synthesis Example B1. These results are shown in Figure 5 and Table 2.

[0110] (Comparative synthesis example B3) <Synthesis of Cyclic Carbonate-Modified Linear Silicone Polymers via Hydrosilylation> To 2.0 g (17.5 mmol) of 4-vinyl-1,3-dioxolan-2-one, 1.31 g (21.7 mmol) of poly(methylhydrosiloxane) (manufactured by Aldrich, Mn: 1700 to 3200), and 1 mg of 2,6-di-tert-butyl-4-methylphenol, 7 g of tetrahydrofuran (THF) was added, and 10 μl of a platinum catalyst (a xylene solution of platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex (Karstedt catalyst manufactured by Aldrich, Pt amount: approximately 2% by mass)) was added, and the mixture was stirred under a nitrogen atmosphere at 70° C. for 10 hours, and the reaction mixture was reacted with the following formula:

[0111] [ka]

[0112] The reaction represented by the following formula was carried out. After that, the resulting reaction solution was dried under vacuum at 60°C to obtain a gel-like substance. Since this gel-like substance was not completely dissolved in deuterated chloroform, the soluble portion was extracted and 1 H-NMR analysis detected only 4-vinyl-1,3-dioxolan-2-one, and no components derived from poly(methylhydrosiloxane). From this result, it is believed that the components derived from poly(methylhydrosiloxane) were insolubilized by crosslinking.

[0113] [Table 2]

[0114] As shown in Table 2, it was confirmed that vacuum dehydration increases the weight average molecular weight (Mw) of the cyclic carbonate-modified linear or branched silicone polymer having a structural unit containing a hydrosilyl group to 2500 or more.

[0115] Furthermore, the results shown in Comparative Synthesis Example B3 demonstrate that it is difficult to obtain a high molecular weight cyclic carbonate-modified silicone polymer by the method of introducing cyclic carbonate groups into poly(methylhydrosiloxane) by hydrosilylation.

[0116] Example 1 35.5 mg of the vinyl-containing cyclic carbonate-modified linear silicone polymer (Mw: 10800, vinyl equivalent: 0.63 mmol / g) obtained in Synthesis Example A2 and 14.5 mg of the hydrosilyl-containing cyclic carbonate-modified linear silicone polymer (Mw: 3360, hydrosilyl equivalent: 1.55 mmol / g) obtained in Synthesis Example B1 were dissolved in 300 μL of acetonitrile, and 5 μL of a platinum catalyst (a xylene solution of platinum (0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex (Karstedt catalyst manufactured by Aldrich, Pt content: approximately 2% by mass)) was added to prepare a crosslinkable silicone composition solution. The crosslink density of this crosslinkable silicone composition solution was calculated to be 0.45 mmol / g, assuming 100% reaction between the vinyl groups and the hydrosilyl groups.

[0117] 300 μl of the resulting crosslinkable silicone composition solution was placed in a Teflon (registered trademark) Petri dish (diameter 20 mm) and dried, and then heated at 130° C. for 5 hours in a nitrogen atmosphere to obtain a compound of the following formula:

[0118] [ka]

[0119] A crosslinked high molecular weight cyclic carbonate-modified silicone elastomer film (diameter: approximately 20 mm, thickness: approximately 70 μm) was prepared by the thermal curing reaction shown in the following formula:

[0120] Example 2 A crosslinkable silicone composition solution was prepared in the same manner as in Example 1, except that 32.1 mg of the vinyl group-containing cyclic carbonate-modified linear silicone polymer (Mw: 6340, vinyl group equivalent: 0.86 mmol / g) obtained in Synthesis Example A3 was used instead of the vinyl group-containing cyclic carbonate-modified linear silicone polymer (Mw: 10800, vinyl group equivalent: 0.63 mmol / g), and the amount of hydrosilyl group-containing cyclic carbonate-modified linear silicone polymer (Mw: 3360, hydrosilyl group equivalent: 1.55 mmol / g) was changed to 17.9 mg. The crosslink density of this crosslinkable silicone composition solution was calculated to be 0.55 mmol / g, assuming 100% reaction between the vinyl groups and the hydrosilyl groups.

[0121] Using the resulting crosslinkable silicone composition solution, a crosslinked high molecular weight cyclic carbonate-modified silicone elastomer film (diameter: approximately 20 mm, thickness: approximately 70 μm) was produced in the same manner as in Example 1.

[0122] Example 3 A crosslinkable silicone composition solution was prepared in the same manner as in Example 1, except that 25.7 mg of the vinyl group-containing cyclic carbonate-modified linear silicone polymer (Mw: 8760, vinyl group equivalent: 1.47 mmol / g) obtained in Synthesis Example A4 was used instead of the vinyl group-containing cyclic carbonate-modified linear silicone polymer (Mw: 10800, vinyl group equivalent: 0.63 mmol / g), and the amount of hydrosilyl group-containing cyclic carbonate-modified linear silicone polymer (Mw: 3360, hydrosilyl group equivalent: 1.55 mmol / g) was changed to 24.3 mg. The crosslink density of this crosslinkable silicone composition solution was calculated to be 0.75 mmol / g, assuming 100% reaction between the vinyl groups and the hydrosilyl groups.

[0123] Using the resulting crosslinkable silicone composition solution, a crosslinked high molecular weight cyclic carbonate-modified silicone elastomer film (diameter: approximately 20 mm, thickness: approximately 70 μm) was produced in the same manner as in Example 1.

[0124] Example 4 A crosslinkable silicone composition solution was prepared in the same manner as in Example 1, except that 19.3 mg of the vinyl group-containing cyclic carbonate-modified linear silicone polymer (Mw: 9770, vinyl group equivalent: 0.46 mmol / g) obtained in Synthesis Example A6 was used instead of the vinyl group-containing cyclic carbonate-modified linear silicone polymer (Mw: 10800, vinyl group equivalent: 0.63 mmol / g), the amount of hydrosilyl group-containing cyclic carbonate-modified linear silicone polymer (Mw: 3360, hydrosilyl group equivalent: 1.55 mmol / g) was changed to 5.7 mg, and 100 μL of acetone was used instead of acetonitrile. The crosslink density of this crosslinkable silicone composition solution was calculated to be 0.35 mmol / g, assuming 100% reaction between the vinyl groups and hydrosilyl groups.

[0125] Using the obtained crosslinkable silicone composition solution, a crosslinked high molecular weight cyclic carbonate-modified silicone elastomer film (diameter: approximately 20 mm, thickness: approximately 70 μm) was produced in the same manner as in Example 1, except that the heating conditions were changed to 70°C x 10 hours.

[0126] (Comparative Example 1) A crosslinkable silicone composition solution was prepared in the same manner as in Example 1, except that 40.4 mg of the vinyl group-containing cyclic carbonate-modified linear silicone polymer (Mw: 9000, vinyl group equivalent: 0.37 mmol / g) obtained in Synthesis Example A5 was used instead of the vinyl group-containing cyclic carbonate-modified linear silicone polymer (Mw: 10800, vinyl group equivalent: 0.63 mmol / g), and the amount of hydrosilyl group-containing cyclic carbonate-modified linear silicone polymer (Mw: 3360, hydrosilyl group equivalent: 1.55 mmol / g) was changed to 9.6 mg. The crosslink density of this crosslinkable silicone composition solution was calculated to be 0.30 mmol / g, assuming 100% reaction between the vinyl groups and hydrosilyl groups.

[0127] Using the resulting crosslinkable silicone composition solution, a crosslinked high molecular weight cyclic carbonate-modified silicone elastomer film (diameter: approximately 20 mm, thickness: approximately 70 μm) was produced in the same manner as in Example 1.

[0128] (Comparative Example 2) A crosslinkable silicone composition solution was prepared in the same manner as in Example 1, except that 20 mg of the cyclic carbonate-modified linear silicone polymer having vinyl groups (Mw: 1540, vinyl group equivalent: 1.62 mmol / g) obtained in Comparative Synthesis Example A2 was used instead of the cyclic carbonate-modified linear silicone polymer having vinyl groups (Mw: 10800, vinyl group equivalent: 0.63 mmol / g), 25 mg of the cyclic carbonate-modified linear silicone polymer having hydrosilyl groups (Mw: 1110, hydrosilyl group equivalent: 1.30 mmol / g) obtained in Comparative Synthesis Example B2 was used instead of the cyclic carbonate-modified linear silicone polymer having hydrosilyl groups (Mw: 3360, hydrosilyl group equivalent: 1.55 mmol / g), and the amount of platinum catalyst was changed to 1 μL. The crosslink density of this crosslinkable silicone composition solution was calculated to be 0.72 mmol / g, assuming 100% reaction between vinyl groups and hydrosilyl groups.

[0129] Using the obtained crosslinkable silicone composition solution, a crosslinked low molecular weight cyclic carbonate-modified silicone elastomer film (diameter: approximately 20 mm, thickness: approximately 70 μm) was produced in the same manner as in Example 1, except that the heating conditions were changed to 100°C x 2 hours + 130°C x 2 hours.

[0130] <Viscoelasticity measurement> The crosslinked cyclic carbonate-modified silicone elastomer films prepared in the Examples and Comparative Examples were peeled from the Petri dish and cut into 10 mm × 5 mm strip-shaped test pieces. The storage modulus, loss modulus, and tan δ of the films were measured using a dynamic viscoelasticity measuring device (IT Measurement & Control Co., Ltd., "DVA-220") at a frequency of 10 Hz. The results are shown in Table 3 and Figure 6. For the film prepared in Example 4, the storage modulus was measured by a tensile test using a load-displacement measuring unit (IMADA Co., Ltd., "FSA-0.5K2-500N") at a tensile speed of 10 mm / min. The film prepared in Comparative Example 1 was too soft to perform viscoelasticity measurements. The film prepared in Comparative Example 2 was even softer, breaking into small pieces when peeled from the Petri dish, making it impossible to prepare test pieces of the required size.

[0131] <Dielectric properties> The crosslinked cyclic carbonate-modified silicone elastomer films prepared in the Examples and Comparative Examples were peeled from the Petri dish, and an Au thin film (thickness: approximately 70 μm) was formed on both sides of the obtained film by magnetron sputtering. Using this Au thin film as an electrode, the relative permittivity and dielectric loss tangent of the film were measured at a frequency of 1 kHz using an impedance analyzer (Keysight "HP4194A"). These results are shown in Table 3. Note that the film prepared in Comparative Example 2 was too soft and broke into small pieces when peeled from the Petri dish, so an Au thin film could not be formed, and therefore the relative permittivity and dielectric loss tangent could not be measured.

[0132] [Table 3]

[0133] As shown in FIG. 6 and Table 3, it was found that the higher the crosslink density, the higher the storage modulus and loss tangent. [Industrial Applicability]

[0134] As explained above, the crosslinkable cyclic carbonate-modified silicone composition of the present invention makes it possible to form a crosslinked cyclic carbonate-modified silicone elastomer that has a high dielectric constant and a low elastic modulus.

[0135] Therefore, the crosslinked cyclic carbonate-modified silicone elastomer of the present invention can be used as a dielectric elastomer layer in an electronic device by forming electrodes on both sides of the film. Such an electronic device can be used as an actuator, for example, by applying a voltage to change the distance between the electrodes. Furthermore, for example, when pressure is applied to cause deformation, the distance between the electrodes changes, resulting in a change in impedance, and thus the device can be used as a pressure sensor. In particular, the crosslinked cyclic carbonate-modified silicone elastomer of the present invention has a high dielectric constant and a low modulus of elasticity, making it useful as a dielectric elastomer layer in high-performance actuators and high-sensitivity sensors.

Claims

1. a linear or branched cyclic carbonate-modified silicone polymer (A) having a weight average molecular weight of 2,500 or more and having a vinyl group-containing structural unit and a cyclic carbonate group-containing structural unit in a side chain; a linear or branched cyclic carbonate-modified silicone polymer (B) having a weight average molecular weight of 2,500 or more and having a structural unit containing a hydrosilyl group and a structural unit containing a cyclic carbonate group in a side chain; Contains In the silicone polymer (A), the proportion of branched-chain structural units relative to the total of linear-chain structural units and branched-chain structural units is 0 to 30 mol %, In the silicone polymer (B), the proportion of branched-chain structural units relative to the total of linear-chain structural units and branched-chain structural units is 0 to 30 mol %, The crosslink density is 0.35 mmol / g or more. A crosslinkable cyclic carbonate-modified silicone composition comprising:

2. 2. The crosslinkable cyclic carbonate-modified silicone composition according to claim 1, wherein the silicone polymer (A) has a structural unit containing a vinyl group at least at the terminal thereof.

3. 2. The crosslinkable cyclic carbonate-modified silicone composition according to claim 1, wherein the silicone polymer (B) has a structural unit containing a hydrosilyl group at least at the terminal.

4. The silicone polymer (A) is represented by the following formula (a): 【Chemical 1】 [In the above formula, A represents a cyclic carbonate group, Z represents either a divalent hydrocarbon group or a divalent hetero group, each of the multiple Rs independently represents a monovalent hydrocarbon group, a is 0.45 to 0.98, b is 0 to 0.50, c is 0 to 0.15, d is 0.01 to 0.20, and a+b+c+d=1] It is expressed as The silicone polymer (B) is represented by the following formula (b): 【Chemistry 2】 [In the formula, A represents a cyclic carbonate group, Z represents either a divalent hydrocarbon group or a divalent hetero group, each of the multiple Rs independently represents a monovalent hydrocarbon group, e is 0.45 to 0.98, f is 0 to 0.45, g is 0 to 0.10, h is 0.01 to 0.15, and e+f+g+h=1] It is expressed as The crosslinkable cyclic carbonate-modified silicone composition according to claim 1 .

5. A hydrosilylation reaction product of the crosslinkable cyclic carbonate-modified silicone composition according to any one of claims 1 to 4, A crosslinked cyclic carbonate-modified silicone elastomer, characterized in that a vinyl group of the silicone polymer (A) and a hydrosilyl group of the silicone polymer (B) form a covalent bond.

6. 6. The crosslinked cyclic carbonate-modified silicone elastomer according to claim 5, wherein the hydrosilylation reaction product is a product crosslinked by a platinum group catalyst.

7. 6. The crosslinked cyclic carbonate-modified silicone elastomer according to claim 5, wherein the crosslink density is 0.35 mmol / g or more.

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