Silicone resin composition and cured product thereof

Abstract

Provided is a silicone resin composition which can be suitably used for applications as a damping material, a potting material, and a heat dissipation material, and can form a cured product having high deformation followability by having excellent extensibility.　This silicone resin composition comprises (A) a cyclic siloxane having a first functional group, (B) a linear polysiloxane having, at both ends of the molecular chain thereof, a second functional group capable of addition reaction with the first functional group, (C) a linear polymer having the first functional group at both ends of the molecular chain thereof, and (D) a photopolymerization initiator or thermosetting catalyst for starting or promoting the addition reaction between the first functional group and the second functional group, wherein: the cyclic siloxane (A) is a cyclic siloxane represented by general formula (1) or (2); the ratio of the number of second functional groups in the linear polysiloxane (B) to the total number of first functional groups in the cyclic siloxane (A) and the linear polymer (C) is 0.5-2.0; and the ratio of the number of moles of the linear polymer (C) to the number of moles of the linear polysiloxane (B) is 0.4-0.6. In general formula (1) and general formula (2), Ra represents the first functional group, each Rb independently represents an alkyl group or a phenyl group, and m represents an integer of 3-5. In general formula (2), n represents an integer of 1-1000.

Description

Silicone resin composition and cured product thereof

[0001] The present invention relates to a silicone resin composition that is cured by light such as ultraviolet light or heat, and more specifically to a silicone resin composition that can form a cured product (such as a silicone gel or silicone rubber) with excellent elongation, and to the cured product thereof.

[0002] Silicone gels have various properties such as flexibility, extensibility, heat resistance, light resistance, or light transmittance, and are therefore used in various fields such as electronic devices, construction, and medicine. In recent years, as the range of uses has become more diverse, there has been a demand for further improvement in the properties of silicone gels. In particular, in applications such as sealing materials for electrical and electronic components, coating materials for sensors, potting materials, damping materials, heat dissipation materials, and optical adhesives (OCR, OCA), silicone gels with excellent deformation conformability are required to withstand stronger impacts and large vibrations. Therefore, there is a growing need for silicone resin compositions that form silicone gels with high deformation conformability, i.e., excellent extensibility.

[0003] Therefore, in order to improve the elongation of the cured product of the silicone resin composition, Patent Document 1 proposes an ultraviolet-curable silicone resin composition that contains a specific linear organopolysiloxane (B) that contains an aliphatic unsaturated group, an organopolysiloxane (A2) that contains more than two mercaptoalkyl groups bonded to a silicon atom, and a specific organopolysiloxane (A1) that contains a dithiol at both ends, wherein the ratio of the number of thiol groups in components (A1+A2) to the number of aliphatic unsaturated groups in component (B) is 1 to 3.

[0004] Patent No. 6426023

[0005] However, the silicone resin composition of Patent Document 1 was proposed as a resin to be interposed between a protective part and an image display part in an image display device, and was not intended for use as a damping material, potting material, or heat dissipation material. Therefore, when used as a damping material, potting material, or heat dissipation material, it is necessary to include a solid filler such as a functional filler in the silicone resin composition in order to adjust the viscosity in the uncured state or to improve heat dissipation performance, but this may harden the cured product and reduce elongation.

[0006] Therefore, the present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a silicone resin composition that can be suitably used for applications such as a damping material, a potting material, and a heat dissipation material, and that has excellent elongation properties and is therefore capable of forming a cured product with high deformation followability.

[0007] As a result of extensive research, the present inventors have discovered that a silicone gel with excellent extensibility can be obtained by reacting a linear polysiloxane having specific functional groups at both ends of the molecular chain with a cyclic siloxane in which a functional group capable of addition reaction with the linear polysiloxane is bonded to the silicon atom. Based on this finding, the present invention has been completed.

[0008] In order to solve the above problems, the silicone resin composition of the present invention comprises a cyclic siloxane (A) having a first functional group, a linear polysiloxane (B) having second functional groups at both ends of the molecular chain that are capable of undergoing an addition reaction with the first functional group, a linear polymer (C) having the first functional groups at both ends of the molecular chain, and a photopolymerization initiator or a thermosetting catalyst (D) that initiates or accelerates the addition reaction between the first functional group and the second functional group, wherein the cyclic siloxane (A) is a cyclic siloxane represented by the following general formula (1) or general formula (2), ａ represents a first functional group, R ｂare each independently an alkyl group or a phenyl group, m is an integer of 3 to 5, and in general formula (2), n is an integer of 1 to 1000, the ratio of the number of second functional groups that the linear polysiloxane (B) has to the total number of first functional groups that the cyclic siloxane (A) and the linear polymer (C) have is 0.5 to 2.0, and the ratio of the amount of substance of the linear polymer (C) to the amount of substance of the linear polysiloxane (B) is 0.4 to 0.6.

[0009]

[0010] The silicone resin composition of the present invention comprises a cyclic siloxane (A) having a first functional group, a linear polysiloxane (B) having second functional groups capable of addition reacting with the first functional group at both ends of the molecular chain, and a linear polymer (C) having the first functional groups at both ends of the molecular chain. By setting the ratio of the amount of substance of the linear polymer (C) to the amount of substance of the linear polysiloxane (B) to be 0.4 to 0.6, the linear polysiloxane (B) is bonded to both ends of the linear polymer (C), thereby lengthening the molecular chain of the polysiloxane. Furthermore, by setting the ratio of the number of second functional groups possessed by the linear polysiloxane (B) to the total number of first functional groups possessed by the cyclic siloxane (A) and the linear polymer (C) to 0.5 to 2.0, the first functional group of the cyclic siloxane (A) and the second functional group at one end of the molecular chain containing the linear polysiloxane (B) and the linear polymer (C) can be bonded by addition reaction, and the second functional group at the other end of the molecular chain containing the linear polysiloxane (B) and the linear polymer (C) can be bonded by addition reaction with the first functional group of another cyclic siloxane (A). Thus, according to the present invention, a structure can be formed in which the molecular chain of a linear copolymer formed by bonding the linear polysiloxane (B) to both ends of the linear polymer (C) by addition reaction is linked between cyclic siloxane (A) molecules. By selecting as this cyclic siloxane (A) a cyclic siloxane represented by general formula (1) or general formula (2) where m is an integer of 3 to 5, the cyclic siloxane (A) will have the same number of first functional groups in its molecule as m, and the cyclic siloxane (A) will have branch points that can bond by addition reaction with linear polysiloxane molecules having second functional groups at their terminals, equal to the number of first functional groups. This allows crosslinking between the cyclic siloxane and the molecular chain of the copolymer containing the linearly chain-extended polysiloxane molecules at these 3 to 5 branch points, resulting in a silicone resin composition having excellent elongation and cured product properties.

[0011] The silicone resin composition of the present invention comprises a cyclic siloxane (A) having a first functional group, a linear polysiloxane (B) having second functional groups at both ends of the molecular chain that are capable of undergoing an addition reaction with the first functional group, and a photopolymerization initiator or a thermosetting catalyst (D) that initiates or accelerates the addition reaction between the first functional group and the second functional group, wherein the cyclic siloxane (A) is a cyclic siloxane represented by the following general formula (1) or general formula (2), wherein in general formula (1) and general formula (2), R ａ represents a first functional group, R ｂ are each independently an alkyl group or a phenyl group, m is an integer of 3 to 5, and in general formula (2), n is an integer of 1 to 1000, and the ratio of the number of second functional groups in the linear polysiloxane (B) to the number of first functional groups in the cyclic siloxane (A) is 0.5 to 2.0.

[0012]

[0013] The silicone resin composition of the present invention comprises a cyclic siloxane (A) having a first functional group and a linear polysiloxane (B) having second functional groups at both ends of its molecular chain that are capable of undergoing an addition reaction with the first functional group. By setting the ratio of the number of second functional groups in the linear polysiloxane (B) to the number of first functional groups in the cyclic siloxane (A) to the number of first functional groups in the linear polysiloxane (B) to be 0.5 to 2.0, the first functional group in the cyclic siloxane (A) is bonded to the second functional group at one end of the molecular chain of the linear polysiloxane (B) by addition reaction, and the second functional group at the other end of the molecular chain of this linear polysiloxane (B) is bonded to the first functional group of another cyclic siloxane (A) by addition reaction. Thus, according to the present invention, a structure in which linear polysiloxanes (B) are linked between cyclic siloxane (A) molecules can be formed during the addition reaction. By selecting as this cyclic siloxane (A) a cyclic siloxane represented by general formula (1) or general formula (2) where m is an integer of 3 to 5, the cyclic siloxane (A) will have the same number of first functional groups in its molecule as m, and the cyclic siloxane (A) will have branch points that can bond by addition reaction with the linear polysiloxane (B) having a second functional group at its terminal, equal to the number of first functional groups. This allows the cyclic siloxane (A) to crosslink with the linear polysiloxane (B) at these 3 to 5 branch points, resulting in a silicone resin composition having excellent elongation properties as a cured product.

[0014] It is also preferred that in the silicone resin composition of the present invention, one of the first functional group and the second functional group is an alkenyl group, and the other of the first functional group and the second functional group is a mercaptoalkyl group or a hydrosilyl group. This allows suitable functional groups to be selected for the cyclic siloxane (A), linear polysiloxane (B), and linear polymer (C), or functional groups for the cyclic siloxane (A) and linear polysiloxane (B), which are components of the silicone resin composition of the present invention. Here, the mercaptoalkyl group is a functional group in which one of the hydrogen atoms constituting the alkyl group is substituted with a mercapto group represented by the general formula SH, and this mercapto group can undergo an addition reaction with the double bond of the alkenyl group to form a C-S-C bond. The hydrosilyl group is a hydrogen atom bonded to a silicon atom represented by the general formula SiH, and can undergo an addition reaction with the double bond of the alkenyl group to form a Si-C bond. Such a reaction causes addition polymerization between the constituent components of the silicone resin composition, resulting in a gel-like or rubber-like cured product with excellent extensibility.

[0015] The cyclic siloxane (A) of the silicone resin composition of the present invention is also preferably a cyclic trisiloxane represented by general formula (1) or general formula (2), in which m is an integer of 3. This allows a particularly preferred material to be selected as the cyclic siloxane (A), a constituent component of the silicone resin composition of the present invention. By using a cyclic trisiloxane, a gel-like or rubber-like cured product with particularly excellent elongation can be obtained.

[0016] In addition, in the silicone resin composition of the present invention, it is also preferable that the first functional group is an alkenyl group, and the second functional group is a mercaptoalkyl group or a hydrosilyl group. Furthermore, it is also preferable that the alkenyl group of this first functional group is a vinyl group. This allows more suitable functional groups to be selected as the functional groups possessed by the cyclic siloxane (A), linear polysiloxane (B) and linear polymer (C), which are components of the silicone resin composition of the present invention, or the functional groups possessed by the cyclic siloxane (A) and linear polysiloxane (B). That is, the first functional group possessed by the cyclic siloxane (A) is preferably an alkenyl group, and particularly preferably a vinyl group. Furthermore, it is preferable that the second functional group possessed by the linear polysiloxane (B) is a mercaptoalkyl group or a hydrosilyl group.

[0017] The silicone resin composition of the present invention preferably further contains at least one functional filler (E) selected from the group consisting of a thixotropic filler, a thermally conductive filler, an electrically conductive filler, a magnetic filler, and a dielectric filler, thereby imparting desired properties to the silicone resin composition and its cured product.

[0018] In addition, the linear polymer (C) in the silicone resin composition of the present invention is preferably an organopolysiloxane represented by the following general formula (3): ａ represents a first functional group, R ｃ are each independently an alkyl group or a phenyl group, and p is an integer of 30 to 2000. By selecting such a linear polymer (C), it is possible to add-react with the linear polysiloxane (B) to extend the chain length of the polysiloxane molecule. This results in a silicone resin composition that can form a stable cured product as a silicone gel.

[0019]

[0020] The cured product of the present invention is obtained by curing the silicone resin composition described above. Due to the above-mentioned configuration, the cured product of the present invention has excellent elongation and high deformation followability.

[0021] The cured product of the present invention preferably has an elongation at break (Eb) of 200% or more (based on JIS K6251:2071) and a complex modulus of elasticity of 1,000 to 100,000 (based on JIS K7244-10), thereby providing a cured product with particularly favorable physical properties.

[0022] The damping member of the present invention is made of the cured product described above. The electronic device of the present invention is equipped with this damping member. The cured product (silicone gel) having the above-described configuration is suitable for use as a damping member, and can be provided as a damping member in precision electronic devices such as camera modules.

[0023] The heat dissipation sheet of the present invention comprises the cured product described above. The electronic device of the present invention is equipped with this heat dissipation sheet. The cured product (silicone gel) having the above-described configuration is suitable for use as a heat dissipation sheet, and can be provided as a heat dissipation sheet in electronic devices such as semiconductor etching devices.

[0024] According to the present invention, it is possible to provide a silicone resin composition that can form a gel-like or rubber-like cured product (silicone gel or silicone rubber) that has excellent elongation. This allows the cured product to have a high elongation at break (Eb), making it difficult for the cured product to break even when a tensile force is applied, and it is possible to provide a damping member or a heat dissipation sheet that has excellent deformation followability.

[0025] The silicone resin composition of the present invention and the cured product thereof will be described in detail below.

[0026] (Silicone Resin Composition) First, a silicone resin composition according to a first embodiment of the present invention will be described. The silicone resin composition according to the first embodiment contains a cyclic siloxane (A) having a first functional group, a linear polysiloxane (B) having second functional groups at both ends of the molecular chain that are capable of undergoing an addition reaction with the first functional group, a linear polymer (C) having the first functional groups at both ends of the molecular chain, and a photopolymerization initiator or a thermosetting catalyst (D) that initiates or promotes the addition reaction between the first functional group and the second functional group.

[0027] (Cyclic Siloxane (A)) The cyclic siloxane (A) contained in the silicone resin composition of this embodiment is a component capable of addition reacting with the linear polysiloxane (B) described later, and is a cyclic siloxane (A1) represented by the following general formula (1) or a cyclic siloxane (A2) represented by the following general formula (2). In the general formulas (1) and (2), R ａ represents a first functional group, R ｂ are each independently an alkyl group or a phenyl group, m is an integer of 3 to 5, and in general formula (2), n is an integer of 1 to 1000.

[0028]

[0029] The cyclic siloxane (A1) represented by the general formula (1) is a cyclic siloxane in which m in the general formula (1) is an integer of 3 to 5, and more specifically, is a cyclic trisiloxane (m=3), a cyclic tetrasiloxane (m=4), or a cyclic pentasiloxane (m=5). Of these, from the viewpoint of excellent elongation of the cured product, cyclic trisiloxane (m=3) or cyclic tetrasiloxane (m=4) is preferred, and cyclic trisiloxane (m=3) is more preferred. The cyclic siloxane (A1) may be a mixture of cyclic trisiloxane, cyclic tetrasiloxane, and cyclic pentasiloxane. The cyclic siloxane (A1) represented by the general formula (1) contains a first functional group R capable of addition reacting with a second functional group of the linear polysiloxane (B) described later. ａ This first functional group R ａ are bonded to the silicon atoms forming the siloxane ring. Therefore, the cyclic siloxane (A1) has first functional groups in the molecule in the same number as the number of silicon atoms forming the siloxane ring, i.e., the number m in general formula (1). ａ The first functional group R is not particularly limited as long as it is a functional group capable of addition reaction with the second functional group of the linear polysiloxane (B), but examples thereof include an alkenyl group, a mercaptoalkyl group, or a hydrosilyl group (general formula -SiH). ａis preferably an alkenyl group from the viewpoint of ease of synthesis or availability of materials. Here, examples of the alkenyl group include a vinyl group, an allyl group, a propenyl group, an isopropenyl group, a 2-methyl-1-propenyl group, a 2-methylallyl group, and a 2-butenyl group, with a vinyl group being particularly preferred. Furthermore, examples of the mercaptoalkyl group include a mercaptoethyl group, a mercaptopropyl group, and a mercaptobutyl group, but in the present invention, the mercapto group (general formula -SH) constituting the mercaptoalkyl group is preferably bonded to the terminal of the alkyl group, with a 2-mercaptopropyl group being particularly preferred.

[0030] The cyclic siloxane (A2) represented by the general formula (2) is a cyclic siloxane in which m is an integer of 3 to 5, more specifically, a cyclic trisiloxane (m=3), a cyclic tetrasiloxane (m=4), or a cyclic pentasiloxane (m=5). Of these, from the viewpoint of excellent elongation of the cured product, cyclic trisiloxane (m=3) or cyclic tetrasiloxane (m=4) is preferred, and cyclic trisiloxane (m=3) is more preferred. The cyclic siloxane (A1) may be a mixture of cyclic trisiloxane, cyclic tetrasiloxane, and cyclic pentasiloxane. The cyclic siloxane (A2) represented by the general formula (2) contains a first functional group R capable of addition reacting with a second functional group of the linear polysiloxane (B) described later. ａ The first functional group R of the cyclic siloxane (A2) ａ is bonded to the end of a siloxane chain, which is formed by bonding another siloxane chain to a silicon atom forming the siloxane ring. Therefore, the cyclic siloxane (A2) has first functional groups in the molecule in the same number as the number of silicon atoms forming the siloxane ring, i.e., the number m in general formula (2). ａ The first functional group R is not particularly limited as long as it is a functional group capable of addition reaction with the second functional group of the linear polysiloxane (B), but examples thereof include an alkenyl group, a mercaptoalkyl group, or a hydrosilyl group (general formula -SiH). ａis preferably an alkenyl group from the viewpoint of ease of synthesis or availability of materials. Examples of alkenyl groups include vinyl, allyl, propenyl, isopropenyl, 2-methyl-1-propenyl, 2-methylallyl, and 2-butenyl groups, with vinyl being particularly preferred. Examples of mercaptoalkyl groups include mercaptoethyl, mercaptopropyl, and mercaptobutyl groups, but in the present invention, the mercapto group (general formula -SH) constituting the mercaptoalkyl group is preferably bonded to the terminal of the alkyl group, with 2-mercaptopropyl being particularly preferred. Furthermore, n in general formula (2) is represented by an integer of 1 to 1,000, preferably 1 to 100, and more preferably 1 to 10.

[0031] In the cyclic siloxane (A1) represented by the general formula (1) and the cyclic siloxane (A2) represented by the general formula (2), R ｂ represents an alkyl group or a phenyl group. ｂ can be each independently an alkyl group or a phenyl group, and may be different for each silicon atom forming a siloxane ring or each silicon atom forming a siloxane chain. ｂ Examples of alkyl groups represented by the formula (I) include methyl, ethyl, propyl, and isopropyl groups, with methyl being preferred. Depending on the physical properties required for the silicone gel, which is the cured product of the silicone resin composition, R ｂ An alkyl group or a phenyl group can be selected for R. ｂ can also be a non-reactive group such as a polyether group, an aralkyl group, a fluoro group, a fluoroalkyl group, a higher fatty acid ester group, or a higher fatty acid amide group.

[0032] In addition, in the cyclic siloxane represented by the general formula (1) or (2), when a cyclic tetrasiloxane in which m in the general formula is 4 is selected, the four first functional groups R ａ and two first functional groups R ａIt is also possible to use a mixture with a cyclic tetrasiloxane having at the para position.

[0033] (Linear Polysiloxane (B)) The linear polysiloxane (B) contained in the silicone resin composition of this embodiment has second functional groups capable of addition reacting with first functional groups at both ends of its molecular chain, and is a component capable of addition reacting with the above-mentioned cyclic siloxane (A) and the linear polymer (C) described below. As a more specific example, the linear polysiloxane (B) can be represented by the following general formula (4). In this general formula (4), R ｄ represents a second functional group, R e are each independently a non-reactive group such as an alkyl group or a phenyl group, and r is an integer of 30 to 2000.

[0034]

[0035] The linear polysiloxane (B) represented by the general formula (4) contains a second functional group R capable of addition reacting with the first functional group of the cyclic siloxane (A) and the linear polymer (C) described later. ｄ The second functional group R ｄ are bonded to the silicon atoms at both ends of the siloxane chain, respectively, and bring about high addition reactivity with the first functional group at both ends of the linear polysiloxane (B). Therefore, the linear polysiloxane (B) is bonded to the cyclic siloxane (A) and the linear polymer (C), and the molecular chain of the linear copolymer formed by bonding the linear polysiloxane (B) to both ends of the linear polymer (C) can be made to act so as to form a structure in which the cyclic siloxane (A) molecules are linked together. ｄ is not particularly limited as long as it is a functional group capable of addition reaction with the first functional group of the cyclic siloxane (A) or the linear polymer (C), and examples thereof include an alkenyl group, a mercaptoalkyl group, and a hydrosilyl group. ｄFrom the viewpoint of ease of synthesis or availability of the material, a mercaptoalkyl group or a hydrosilyl group is preferred, with a mercaptoalkyl group being particularly preferred. Examples of alkenyl groups include vinyl, allyl, propenyl, isopropenyl, 2-methyl-1-propenyl, 2-methylallyl, and 2-butenyl groups, with a vinyl group being particularly preferred. Examples of mercaptoalkyl groups include mercaptoethyl, mercaptopropyl, and mercaptobutyl groups, but in the present invention, the mercapto group constituting the mercaptoalkyl group is preferably bonded to the terminal of the alkyl group, with a 2-mercaptopropyl group being particularly preferred. Furthermore, r, which indicates the degree of polymerization in general formula (4), is represented by an integer of 30 to 2000. By setting the value of r in general formula (4) to be in the range of 30 to 2000, a cured product with excellent elongation and high deformation followability can be obtained. Furthermore, from the viewpoint of improving the elongation of the obtained cured product and adjusting the complex modulus of elasticity of the cured product within a preferred range, the sum (p+r) of r in general formula (4) of the linear polysiloxane (B) and p in general formula (3) of the linear polymer (C) described below is preferably 30 to 6,000, more preferably 50 to 3,000.

[0036] In the linear polysiloxane (B) represented by the general formula (4), R e R is preferably a non-reactive group. Examples of the non-reactive group include an alkyl group, a phenyl group, a polyether group, an aralkyl group, a fluoro group, a fluoroalkyl group, a higher fatty acid ester group, or a higher fatty acid amide group, and among these, an alkyl group or a phenyl group is preferably selected depending on the physical properties required for the cured product of the silicone resin composition. e R can be independently an alkyl group or a phenyl group, and may be different for each silicon atom forming the siloxane chain. e Examples of the alkyl group represented by the formula (I) include a methyl group, an ethyl group, a propyl group, and an isopropyl group, and a methyl group is preferred.

[0037] (Linear Polymer (C)) The linear polymer (C) contained in the silicone resin composition of this embodiment has first functional groups at both ends of its molecular chain and is a component capable of addition reacting with the linear polysiloxane (B) described above. Here, the first functional group is the same functional group as the first functional group possessed by the cyclic siloxane (A). The linear polymer is not particularly limited as long as it is a polymer having the first functional groups bonded to both ends of its molecular chain, and examples thereof include polymers such as polysiloxane, polyolefin, polyurethane, polyamide, polyester, polystyrene, and combinations thereof. Of these, from the viewpoint of improving the stability of the resulting cured product (silicone gel or silicone rubber) in terms of heat resistance, weather resistance, chemical resistance, etc., the linear polymer (C) is preferably a polysiloxane, and a more specific example is an organopolysiloxane represented by the following general formula (3). In general formula (3), R ａ represents a first functional group, R ｃ are each independently a non-reactive group such as an alkyl group or a phenyl group, and p is an integer of 30 to 2000.

[0038]

[0039] In the linear polymer (C) represented by the general formula (3), a first functional group R capable of addition reaction with a second functional group possessed by the linear polysiloxane (B) is ａ In this linear organopolysiloxane (C), the first functional group R ａ are bonded to the silicon atoms at both ends of the siloxane chain, respectively, and bring about high addition reactivity with the second functional group at both ends of this molecule. Therefore, the linear polysiloxane (B) is bonded to both ends of the linear polymer (C), respectively, and can act to lengthen the molecular chain of the polysiloxane. The first functional group R ａ The explanation for the first functional group R ａSince the configuration is similar to that of the linear polymer (C) in the general formula (3), a description thereof will be omitted. Furthermore, p, which indicates the degree of polymerization, is expressed as an integer of 30 to 2000. By setting the value of p in the general formula (3) to be in the range of 30 to 2000, a cured product having excellent elongation and high deformation followability can be obtained. Furthermore, from the viewpoint of improving the elongation of the resulting cured product and adjusting the complex modulus to a preferred range, the sum (p + r) of p in the general formula (3) of the linear polymer (C) and r in the general formula (4) of the linear polysiloxane (B) described above is preferably 30 to 6000, more preferably 50 to 3000.

[0040] In the linear polymer (C) represented by the general formula (3), R ｃ R is preferably a non-reactive group. Examples of the non-reactive group include an alkyl group, a phenyl group, a polyether group, an aralkyl group, a fluoro group, a fluoroalkyl group, a higher fatty acid ester group, or a higher fatty acid amide group, and among these, an alkyl group or a phenyl group is preferably selected depending on the physical properties required for the cured product of the silicone resin composition. ｃ R can be independently an alkyl group or a phenyl group, and may be different for each silicon atom forming the siloxane chain. ｃ Examples of the alkyl group represented by the formula (I) include a methyl group, an ethyl group, a propyl group, and an isopropyl group, and a methyl group is preferred.

[0041] The first functional group and the second functional group of the constituent components of the silicone resin composition according to this embodiment are not particularly limited as long as they are capable of undergoing an addition reaction with each other, but it is preferred that one of the first functional group and the second functional group is an alkenyl group and the other of the first functional group and the second functional group is a mercaptoalkyl group or a hydrosilyl group. That is, the first functional group R of the cyclic siloxane (A) and the linear polymer (C) ａ is an alkenyl group, the second functional group R ｄ is preferably a mercaptoalkyl group or a hydrosilyl group.ａ is a mercaptoalkyl group or a hydrosilyl group, the second functional group R of the linear polysiloxane (B) ｄ is preferably an alkenyl group. Examples of alkenyl groups include vinyl, allyl, propenyl, isopropenyl, 2-methyl-1-propenyl, 2-methylallyl, and 2-butenyl groups, with vinyl being particularly preferred. Examples of mercaptoalkyl groups include mercaptoethyl, mercaptopropyl, and mercaptobutyl groups. In the present invention, the mercapto group (general formula -SH) constituting the mercaptoalkyl group is preferably bonded to the terminal of the alkyl group, with 2-mercaptopropyl being particularly preferred. This mercapto group can undergo an addition reaction with the double bond of the alkenyl group to form a C-S-C bond. Furthermore, hydrosilyl groups are hydrogen atoms bonded to silicon atoms, represented by the general formula -SiH, and can undergo an addition reaction with the double bond of the alkenyl group to form an Si-C bond. Such a reaction allows addition polymerization between the components of the silicone resin composition, resulting in a silicone gel with excellent elongation.

[0042] In the silicone resin composition according to this embodiment, the first functional group R of the cyclic siloxane (A) and the linear polymer (C) ａ is an alkenyl group such as a vinyl group, and the second functional group R ｄ When the alkenyl group R of the cyclic siloxane (A) is a mercaptoalkyl group, an addition reaction between the first functional group and the second functional group can be caused by a light energy reaction. Therefore, the silicone resin composition preferably contains a photopolymerization initiator as component (D) that initiates or accelerates the addition reaction between the first functional group and the second functional group. ａ and the mercaptoalkyl group R at the end of the linear polysiloxane (B). ｄ When the cyclic siloxane (A) and the linear polysiloxane (B) undergo an addition reaction, the cyclic siloxane (A) and the linear polysiloxane (B) can be linked together. On the other hand, the alkenyl groups R at both ends of the linear polymer (C) ａ and each represent a mercaptoalkyl group R of the linear polysiloxane (B). ｄWhen the linear polysiloxane (B) is added to both ends of the linear polymer (C), a linear polysiloxane copolymer with an increased molecular chain length can be formed. These addition reactions occur in a chain-like manner, forming a polymer in which the cyclic siloxane (A) molecules and the linear polysiloxane copolymer molecules are crosslinked. Note that the first functional group R of the cyclic siloxane (A) and the linear polymer (C) ａ is a mercaptoalkyl group, and the second functional group R ｄ is an alkenyl group, the same explanation applies with the functional groups interchanged.

[0043] In the silicone resin composition according to this embodiment, the first functional group R ａ is an alkenyl group such as a vinyl group, and the second functional group R ｄ When the alkenyl group R of the cyclic siloxane (A) is a hydrosilyl group, an addition reaction between the first functional group and the second functional group can be caused by a thermal reaction. Therefore, the silicone resin composition preferably contains a heat curing catalyst as component (D) that initiates or accelerates the addition reaction between the first functional group and the second functional group. ａ and the hydrosilyl group R at the end of the linear polysiloxane (B). ｄ When the cyclic siloxane (A) and the linear polysiloxane (B) undergo an addition reaction, the cyclic siloxane (A) and the linear polysiloxane (B) can be linked together. On the other hand, the alkenyl groups R at both ends of the linear polymer (C) ａ and each represent a hydrosilyl group R of the linear polysiloxane (B). ｄ When the linear polysiloxane (B) is added to both ends of the linear polymer (C), a linear polysiloxane copolymer with an increased molecular chain length can be formed. These addition reactions occur in a chain-like manner, forming a polymer in which the cyclic siloxane (A) molecules and the linear polysiloxane copolymer molecules are crosslinked. Note that the first functional group R of the cyclic siloxane (A) and the linear polymer (C) ａ is a hydrosilyl group, and the second functional group R ｄis an alkenyl group, the same explanation applies with the functional groups interchanged.

[0044] In the silicone resin composition of the present embodiment, the ratio of the amount of substance of the linear polymer (C) to the amount of substance of the linear polysiloxane (B), i.e., [amount of substance of (C) / amount of substance of (B)], is preferably 0.4 to 0.6, more preferably 0.42 to 0.58, and particularly preferably 0.45 to 0.55, from the viewpoint of bonding the linear polysiloxane (B) to both ends of the linear polymer (C) and efficiently extending the molecular chain of the polysiloxane molecule to form a linear polysiloxane copolymer. Furthermore, the ratio of the number of second functional groups in the linear polysiloxane (B) to the total number of first functional groups in the cyclic siloxane (A) and the linear polymer (C), i.e., [number of second functional groups / total number of first functional groups], can be appropriately set depending on the total molecular chain length (total molecular weight) of the linear polysiloxane (B) and the linear polymer (C), and is preferably 0.5 to 2.0, more preferably 0.5 to 1.6, and particularly preferably 0.7 to 1.4. More specifically, when the total molecular chain length (total molecular weight) of the linear polysiloxane (B) and the linear polymer (C) is small, it is preferable to design it within the smaller range, and when the total molecular chain length (total molecular weight) is large, it is preferable to design it within the larger range. More specifically, when the total molecular weight of the linear polysiloxane (B) and the linear polymer (C) is less than 20,000, the ρ is more preferably 0.5 to 1.2, and particularly preferably 0.7 or more and less than 1.0. Furthermore, when the total molecular weight of the linear polysiloxane (B) and the linear polymer (C) is 20,000 or more, the ρ is more preferably 0.7 to 1.6, and particularly preferably 0.8 to 1.4. This allows the first functional group of the cyclic siloxane (A) to undergo an addition reaction and bond with the second functional group at one end of the molecular chain of the linear polysiloxane copolymer containing the linear polysiloxane (B) and the linear polymer (C), and also allows the second functional group at the other end of the molecular chain of this linear polysiloxane copolymer to undergo an addition reaction and bond with the first functional group of another cyclic siloxane (A). As described above, according to the present invention, an addition reaction can be performed to form a structure in which two cyclic siloxane (A) molecules are linked by a molecular chain of a linear polysiloxane copolymer containing a linear polysiloxane (B) and a linear polymer (C).The molecular weight in the present invention refers to the weight average molecular weight Mw, which is measured by gel permeation chromatography (GPC).

[0045] (Photopolymerization initiator / thermosetting catalyst (D)) The photopolymerization initiator (D1) is a compound that reacts with the first functional group R ａ and the second functional group R ｄThe above combination is used, for example, in the case of a combination of an alkenyl group and a mercaptoalkyl group, and is a component capable of initiating an addition reaction between the mercapto group of the mercaptoalkyl group and the alkenyl group. As the photopolymerization initiator (D1), known compounds that act on a thiol-ene reaction under ultraviolet irradiation can be used. Examples of the photopolymerization initiator (D1) include 1-hydroxy-cyclohexyl-phenyl-ketone, 2,2-dimethoxy-2-phenylacetophenone, xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, triphenylamine, carbazole, 3-methylacetophenone, 4-chlorobenzophenone, 4,4'-dimethoxybenzophenone, 4,4'-diaminobenzophenone, Michler's ketone, benzoin propyl ether, benzoin ethyl ether, benzil dimethyl ketal, 1-(4-isopropylphenyl)-2-hydroxybenzophenone ... benzoin propyl ether, benzoin propyl ether, benzoin propyl ether, benzoin propyl ether, benzoin propyl ether, benzoin propyl ether, benzoin propyl ether, benzoin propyl ether, benzoin propyl ether, benzoin propyl ether, benzoin propyl ether, benzoin propyl ether, benzoin propyl ether, benzo Examples of the photopolymerization initiator (D1) include 2-hydroxy-2-methylpropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, thioxanthone, diethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide; Omnirad 184, 369, 651, 500, 907, 1173, and TPO H (all manufactured by BASF). The photopolymerization initiator (D1) can be used alone or in combination of two or more materials. The amount of the photopolymerization initiator to be added may be an amount effective for initiating a thiol-ene reaction by active energy rays, and is preferably 0.05 to 50 parts by mass, and more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the total amount of the cyclic siloxane (A), the linear polysiloxane (B), and the linear polymer (C).

[0046] The thermosetting catalyst (D2) is a compound having a first functional group R ａ and the second functional group R ｄThe above combination is used, for example, when an alkenyl group and a hydrosilyl group are combined, and is a component that can promote the reaction between the hydrosilyl group and the alkenyl group. The thermosetting catalyst (D2) can be a known catalyst used in hydrosilylation reactions. Examples of the thermosetting catalyst (D2) include platinum group metals such as platinum, rhodium, and palladium; platinum group catalysts such as chloroplatinic acid, alcohol-modified chloroplatinic acid, a complex of chloroplatinic acid and vinylsiloxane, a chloroplatinic acid-2-ethylhexanol solution, tetrakis(triphenylphosphine)palladium, and a mixture of palladium black and triphenylphosphine. The thermosetting catalyst (D1) can be formulated alone or in combination of two or more materials. The amount of the thermosetting catalyst to be added may be an amount effective for accelerating the hydrosilylation reaction by heat, and is preferably an amount that is 0.1 to 500 ppm, more preferably 1.0 to 100 ppm, in terms of the amount of metal atoms contained in the thermosetting catalyst, based on the total amount of the cyclic siloxane (A), the linear polysiloxane (B), and the linear polymer (C), by mass.

[0047] (Functional Filler (E)) The silicone resin composition according to the first embodiment of the present invention may further contain at least one functional filler (E) selected from the group consisting of thixotropic fillers, thermally conductive fillers, electrically conductive fillers, magnetic fillers, and dielectric fillers. These functional fillers have the function of imparting desired properties to the silicone resin composition or a cured product thereof. The functional filler is contained in the silicone resin composition in an appropriate proportion within a range that does not impair the effects of the present invention.

[0048] The thixotropic filler is a component that can impart thixotropy to the silicone resin composition, i.e., the property of high viscosity in the low shear rate region and decreasing viscosity in the high shear rate region. Known thixotropic fillers can be used alone or in combination of two or more. Examples of preferred thixotropic fillers include inorganic fine particles such as finely divided silica, calcium carbonate, heavy calcium carbonate, bentonite, and sepiolite; resin fine particles such as Teflon (registered trademark) and silicone; organic compounds such as long-chain fatty acid ester polymers, amide wax, oxidized polyethylene wax, sulfate ester-based anionic surfactants, polycarboxylic acids, polycarboxylic acid amine salts, and polyethers; and the shape of the fine particles can be appropriately selected from spherical, rod-like, and scale-like shapes.

[0049] The thermally conductive filler is a component that imparts thermal conductivity to the silicone resin composition or its cured product, and known fillers can be used alone or in combination of two or more. Examples of thermally conductive fillers include silica (quartz), aluminum oxide (alumina), aluminum hydroxide, magnesia, zinc oxide, boron nitride, aluminum nitride, silicon nitride, mica, ferrite, graphite, carbon nanotubes, and carbon microcoils.

[0050] The conductive filler is a component that imparts electrical conductivity to the silicone resin composition or its cured product, and known fillers can be used alone or in combination of two or more. Examples of conductive fillers that can be used include metals, carbon materials such as graphite, carbon nanotubes, carbon microcoils, and fullerenes, as well as metal oxides such as zinc oxide.

[0051] The magnetic filler is a component that imparts magnetism to the silicone resin composition or a cured product thereof, and known magnetic fillers can be used alone or in combination of two or more. Examples of magnetic fillers include iron alloys such as iron powder, Fe—Si alloy powder, Fe—Ni alloy powder, Fe—Co alloy powder, Fe—Cr alloy powder, and Fe—Cr—Si alloy powder, spinel ferrites such as Mg—Zn ferrite, Mn—Zn ferrite, Mn—Mg ferrite, Cu—Zn ferrite, Mg—Mn—Sr ferrite, and Ni—Zn ferrite, and hexagonal ferrites such as Ba—Zn ferrite, Ba—Mg ferrite, Ba—Ni ferrite, Ba—Co ferrite, and Ba—Ni—Co ferrite.

[0052] The dielectric filler is a component that imparts dielectric properties to the silicone resin composition or its cured product, and known dielectric fillers can be used alone or in combination of two or more. Examples of the dielectric filler include highly dielectric ceramic powders such as barium titanate, lead zirconate titanate (PZT), lanthanum-doped lead zirconate titanate (PLZT), strontium titanate, lead titanate, bismuth titanate, and bismuth barium titanate, as well as organic compounds having a thiocarbonyl group such as thiourea derivatives, thioamide derivatives, thioketone derivatives, and dithiocarbamate derivatives.

[0053] (Physical Properties of Silicone Resin Composition) Of the physical properties of the silicone resin composition according to this embodiment, the viscosity of the composition can be appropriately set depending on the application. From the viewpoint of coatability and dischargeability using a dispenser or the like, the viscosity at 23°C is preferably 50 to 100,000 cP, more preferably 70 to 9,000 cP, and even more preferably 100 to 7,000 cP.

[0054] The silicone resin composition according to this embodiment can be obtained by mixing the above-described cyclic siloxane (A), linear polysiloxane (B), linear polymer (C), and component (D) that initiates or accelerates the addition reaction, as well as a functional filler (E) and other various components, which are added as needed, in a predetermined mixing ratio. The order in which the above-described components (A) to (D) or (A) to (E) are mixed is not particularly limited. The mixing means is not particularly limited, and examples that can be used include a single-screw extruder, a twin-screw extruder, a kneader, a Banbury mixer, and a roll mill.

[0055] (Cured Product of Silicone Resin Composition) Next, the cured product of the silicone resin composition according to this embodiment will be described. The cured product according to this embodiment is a gel-like or rubber-like cured product (silicone rubber or silicone gel) formed by an addition reaction of the components of the silicone resin composition described above. The cured product thus formed has excellent elongation, and from the viewpoint of realizing high deformation followability, it is preferable that the elongation at break (Eb) is 200% or more (based on JIS K6251:2071), more preferably 1000% or more, and particularly preferably 1500% or more. These physical property values ​​can be designed to desired values ​​by adjusting the structure and amount of the cyclic siloxane (A) that acts as a branch point of the crosslinked structure of the cured product, and the molecular chain length of the linear polysiloxane copolymer, respectively. Furthermore, from the viewpoint of realizing high damping properties for use as a damping material, the cured product of the present invention preferably has a complex modulus of elasticity of 1,000 to 100,000 (in accordance with JIS K7244-10), more preferably 1,500 to 80,000, and particularly preferably 2,000 to 50,000.

[0056] (Applications of Cured Product) The cured product according to this embodiment has excellent elongation and high deformation followability, and therefore can be used as a damping material, potting material, heat dissipation material, sealing material, coating material, vibration-proofing material, vibration-damping material, and optical adhesive (OCR, OCA). Furthermore, the cured product according to this embodiment also has an excellent complex modulus of elasticity and exhibits high damping properties, and therefore this cured product is suitable for use as a damping member that supports precision components such as camera modules and absorbs vibrations. Furthermore, since the cured product according to this embodiment has excellent elongation, even when a heat-dissipating sheet is formed by blending a high proportion of a thermally conductive filler into the silicone resin composition, the elongation is maintained and the sheet is resistant to breakage, and therefore it is suitable for use as a durable heat-dissipating sheet that dissipates heat generated from semiconductor etching equipment and absorbs vibrations.

[0057] Next, a silicone resin composition according to a second embodiment of the present invention will be described. The silicone resin composition according to the second embodiment contains a cyclic siloxane (A) having a first functional group, a linear polysiloxane (B) having second functional groups at both ends of the molecular chain that are capable of undergoing an addition reaction with the first functional group, and a photopolymerization initiator or thermosetting catalyst (D) that initiates or promotes the addition reaction between the first functional group and the second functional group. This embodiment differs from the first embodiment in that it does not contain the linear polymer (C) that was a constituent component. Below, the silicone resin composition according to the second embodiment will be mainly described in terms of the configuration that differs from the first embodiment.

[0058] (Linear Polysiloxane (B)) The linear polysiloxane (B) is a component that has second functional groups capable of undergoing addition reaction with the first functional group at both ends of its molecular chain and is capable of undergoing addition reaction with the above-mentioned cyclic siloxane (A). As a more specific example, the linear polysiloxane (B) can be represented by the following general formula (4). In this general formula (4), R ｄ represents a second functional group, R e are each independently a non-reactive group such as an alkyl group or a phenyl group, and r is an integer of 30 to 6,000.

[0059]

[0060] The linear polysiloxane (B) represented by the general formula (4) contains a second functional group R capable of addition reacting with the first functional group of the cyclic siloxane (A). ｄ The second functional group R ｄ are bonded to the silicon atoms at both ends of the siloxane chain, respectively, and bring about high addition reactivity with the first functional group at both ends of the linear polysiloxane (B). Therefore, the linear polysiloxane (B) bonds with the cyclic siloxane (A), and can act to lengthen the polysiloxane chain between the two cyclic siloxane (A) molecules. ｄ is a functional group capable of addition reaction with the first functional group of the cyclic siloxane (A), and the second functional group R ｄ In addition, the functional group R of the side chain bonded to the silicon atom of the siloxane chain can be the same as e Regarding the R of the side chain of the linear polysiloxane (B) in the first embodiment, e The side chain can be the same as that described above. Furthermore, r in general formula (4) is represented by an integer of 30 to 6000, and from the viewpoint of improving the extensibility of the resulting cured product, it is preferably 50 to 5000, and more preferably 100 to 4000. By setting the numerical value of r in general formula (4) within this range, excellent extensibility can be obtained, and a silicone gel with high deformation followability can be obtained.

[0061] The first functional group and the second functional group contained in the constituent components of the silicone resin composition according to this embodiment are not particularly limited as long as they are capable of undergoing an addition reaction with each other, but it is preferred that one of the first functional group and the second functional group is an alkenyl group and the other of the first functional group and the second functional group is a mercaptoalkyl group or a hydrosilyl group. ａ is an alkenyl group, the second functional group R ｄ is preferably a mercaptoalkyl group or a hydrosilyl group. ａ is a mercaptoalkyl group or a hydrosilyl group, the second functional group R of the linear polysiloxane (B) ｄis preferably an alkenyl group.

[0062] In the silicone resin composition according to this embodiment, the first functional group R ａ is an alkenyl group such as a vinyl group, and the second functional group R ｄ When the alkenyl group R of the cyclic siloxane (A) is a mercaptoalkyl group, an addition reaction between the first functional group and the second functional group can be caused by a light energy reaction. Therefore, the silicone resin composition preferably contains a photopolymerization initiator as component (D) that initiates or accelerates the addition reaction between the first functional group and the second functional group. ａ and the mercaptoalkyl group R at the end of the linear polysiloxane (B). ｄ When the first functional group R of the cyclic siloxane (A) undergoes an addition reaction, the cyclic siloxane (A) and the linear polysiloxane (B) can be linked together. These addition reactions occur in a chain reaction, forming a polymer in which the linear polysiloxane (B) is linked between the cyclic siloxane (A) molecules. ａ is a mercaptoalkyl group, and the second functional group R ｄ is an alkenyl group, the same explanation applies with the functional groups interchanged.

[0063] In the silicone resin composition of the present embodiment, the first functional group R ａ is an alkenyl group such as a vinyl group, and the second functional group R ｄ When the alkenyl group R of the cyclic siloxane (A) is a hydrosilyl group, an addition reaction between the first functional group and the second functional group can be caused by a thermal reaction. Therefore, the silicone resin composition preferably contains a heat curing catalyst as component (D) that initiates or accelerates the addition reaction between the first functional group and the second functional group. ａ and the hydrosilyl group R at the end of the linear polysiloxane (B). ｄWhen the first functional group R of the cyclic siloxane (A) undergoes an addition reaction, the cyclic siloxane (A) and the linear polysiloxane (B) can be linked together. These addition reactions occur in a chain reaction, forming a polymer in which the linear polysiloxane (B) is linked between the cyclic siloxane (A) molecules. ａ is a hydrosilyl group, and the second functional group R ｄ is an alkenyl group, the same explanation applies with the functional groups interchanged.

[0064] In the silicone resin composition according to this embodiment, the ratio of the number of second functional groups in the linear polysiloxane (B) to the number of first functional groups in the cyclic siloxane (A), i.e., [number of second functional groups / number of first functional groups], can be appropriately set depending on the molecular chain length (molecular weight) of the linear polysiloxane (B), and is preferably 0.5 to 2.0, more preferably 0.5 to 1.6, and particularly preferably 0.7 to 1.4. More specifically, when the molecular chain length (molecular weight) of the linear polysiloxane (B) is small, it is preferably designed to be on the smaller side of the above range, and when the molecular chain length (molecular weight) is large, it is preferably designed to be on the larger side of the above range. More specifically, when the molecular weight of the linear polysiloxane (B) is less than 20,000, the ratio is more preferably 0.5 to 1.2, and particularly preferably 0.7 or more but less than 1.0. Furthermore, when the molecular weight of the linear polysiloxane (B) is 20,000 or more, the molecular weight is more preferably 0.7 to 1.6, and particularly preferably 0.8 to 1.4. This allows the first functional group of the cyclic siloxane (A) to be bonded to the second functional group at one end of the linear polysiloxane (B) by addition reaction, and also allows the second functional group at the other end of the linear polysiloxane (B) to be bonded to the first functional group of another cyclic siloxane (A) by addition reaction. Thus, according to the present invention, the linear polysiloxane (B) molecule is bonded between the cyclic siloxane (A) molecule and the cyclic siloxane (A) molecule by addition reaction, thereby forming a structure in which the molecular chain between the cyclic siloxane (A) molecules is elongated.

[0065] The other explanations regarding the cyclic siloxane (A) and linear polysiloxane (B) molecules, which are components of the silicone resin composition according to this embodiment, are the same as those in the silicone resin composition according to the first embodiment described above, and the effects thereof are also the same. Furthermore, the explanations regarding the photopolymerization initiator / thermosetting catalyst (D) and functional filler (E), which are components of the silicone resin composition according to this embodiment, are the same as those in the silicone resin composition according to the first embodiment described above, and the effects thereof are also the same.

[0066] The silicone resin composition according to this embodiment can be obtained by mixing the above-mentioned cyclic siloxane (A), linear polysiloxane (B), and component (D) that initiates or accelerates the addition reaction, as well as a functional filler (E) and other various components, which are added as needed, in a predetermined mixing ratio. The order in which the above-mentioned components (A), (B), and (D) or components (A), (B), (D), and (E) are mixed is not particularly limited. The mixing means is not particularly limited, and examples that can be used include a single-screw extruder, a twin-screw extruder, a kneader, a Banbury mixer, and a roll mill.

[0067] The cured product according to this embodiment is a gel-like or rubber-like cured product (silicone rubber or silicone gel) formed by an addition reaction of the components of the silicone resin composition described above. The cured product thus formed has excellent elongation, and from the viewpoint of realizing high deformation followability, the elongation at break (Eb) is preferably 200% or more (based on JIS K6251:2071), more preferably 500% or more, and particularly preferably 1000% or more. These physical property values ​​can be designed to the desired values ​​by adjusting the structure and amount of the cyclic siloxane (A) that acts as a branch point of the crosslinked structure, and the molecular chain length of the linear polysiloxane (B). Furthermore, from the viewpoint of achieving high damping properties for use as a damping material, the cured product according to this embodiment preferably has a complex modulus of 1,000 to 100,000 (in accordance with JIS K7244-10), more preferably a complex modulus of 1,500 to 80,000, and particularly preferably a complex modulus of 2,000 to 50,000. Furthermore, since the silicone gel according to this embodiment has excellent elongation and high deformation followability, it can be used as a damping material, potting material, heat dissipation material, sealing material, coating material, vibration-proof material, vibration-damping material, and optical adhesive (OCR, OCA). Furthermore, since the cured product according to this embodiment also has an excellent complex modulus and exhibits high damping properties, this cured product is suitable for use as a damping member that supports precision components such as camera modules and absorbs vibrations. Furthermore, since the cured product according to this embodiment has excellent elongation properties, even when a heat-dissipating sheet is formed by blending a high proportion of thermally conductive filler into the silicone resin composition, the elongation properties are maintained and the sheet is less likely to break, making it suitable for use as a durable heat-dissipating sheet that dissipates heat generated from semiconductor etching equipment and absorbs vibrations.

[0068] The present invention will be described in more detail below with reference to examples and comparative examples. However, the present invention is not limited to these examples. The elongation at break (Eb) and complex modulus G of the cured product of the silicone resin composition in the following examples and comparative examples were measured. ＊ The methods for measuring and evaluating the physical properties are as follows:

[0069] [Measurement and Evaluation Methods] (1) Elongation at Break (Eb) A cured product of the silicone resin composition was prepared into a sheet having a thickness of 2 mm, and the sheet was punched using a No. 6 dumbbell to prepare a measurement sample. The measurement sample was measured for elongation at break (tensile break) (Eb) as a percentage (%) of elongation at break at 23°C under conditions of 500 mm / min using a tensile tester (AG-Xplus, manufactured by Shimadzu Corporation) in accordance with JIS K6251:2017.

[0070] (2) Evaluation of Elongation at Break Comparative compositions were prepared, each of which had the same components except for the cyclic siloxane (A), but had the same ratio of the number of second functional groups to the total number of first functional groups (second functional groups / first functional groups) and the same ratio of the amount of substance of the linear polymer (C) to the amount of substance of the linear polysiloxane (B) [amount of substance of (C) / amount of substance of (B)]. The elongation at break (%) of the comparative sample was compared with the elongation at break (%) of the corresponding example sample. A sample with a higher elongation than that of the comparative example was judged as passing (◯), while a sample with a lower or equal elongation than that of the comparative example was judged as failing (×). The comparative examples corresponding to the examples described below are as follows: Comparative Example 1 for Examples 1 and 2, Comparative Example 2 for Example 3, Comparative Example 3 for Example 4, Comparative Example 4 for Example 6, Comparative Example 5 for Example 10, and Comparative Example 6 for Example 12.

[0071] (3) Complex elastic modulus G ＊ The cured product of the silicone resin composition was prepared into a sheet with a thickness of 2 mm, and then cut into a φ25 mm or φ8 mm to prepare measurement samples. The dynamic viscoelasticity of each measurement sample was measured using a rheometer (ARES-G2, manufactured by TA Instruments) in accordance with JIS K7244-10, and the complex modulus G at 25°C and 10 Hz was measured. ＊ obtained.

[0072] The specifications of the components of the silicone resin compositions prepared in the following Examples and Comparative Examples are shown in Table 1. The molecular weight and degree of polymerization indicated by p or r of each component shown in the table are design values ​​listed in the respective product specifications or calculated values ​​based on the molecular formula.

[0073]

[0074] Example 1 A silicone resin composition and a cured product thereof of this example were prepared according to the following procedure, and various physical properties were measured using the tests described above. The blending ratios of the components of the silicone resin composition of this example are shown in Table 2 below. The material numbers in Table 2 correspond to the material numbers shown in Table 1. The components shown in Table 1 were used, and the cyclic siloxane (A) was a cyclic trisiloxane (A1-1) having a vinyl group as the first functional group, the linear polysiloxane (B) was a linear polysiloxane (B1) having mercaptopropyl groups at both ends as second functional groups and a molecular weight of 4,600, the linear polymer (C) was a polydimethylsiloxane (C1) having vinyl groups at both ends as first functional groups and a molecular weight of 28,000, and the photopolymerization initiator was BASF's product name: Omnirad 1173 (D1). 0.186 g of Component A1-1, 12.07 g of Component B1, 36.74 g of Component C1, and 1.00 g of Component D1 were weighed and placed in a lidded plastic container. The components were blended so that the ratio of the number of mercaptopropyl groups (second functional groups) to the total number of vinyl groups (first functional groups) in the components was 1.1. The components were blended so that the ratio of the amount of the linear polymer (C) to the amount of the linear polysiloxane (B) [amount of substance of (C) / amount of substance of (B)] was 0.5. The ratio of the number of second functional groups / first functional groups and the ratio of the amount of substance of component (C) / component (B) shown in Table 2 were calculated based on the molecular weight values ​​of each material shown in Table 1. This blend was kneaded for 3 minutes at 2000 rpm using a planetary centrifugal mixer (product name: Awatori Rentaro (registered trademark) ARE-350, manufactured by Thinky Corporation) and then centrifugal degassed for 1 minute at 2200 rpm to obtain the silicone resin composition of Example 1. The resulting silicone resin composition was formed into a sheet on a transparent glass sheet so that the thickness of the cured product was 2 mm, and ultraviolet light having a wavelength of 365 nm was irradiated from the top and bottom surfaces at 3000 mJ / cm. ２ The cured product was subjected to irradiation at different temperatures to obtain a sheet-like cured product. The elongation at break (Eb) and complex modulus G were measured according to the above-mentioned measurement methods. ＊ Measurements and evaluations were carried out.

[0075] In this example, the silicone resin composition of Example 2 was obtained in the same manner as in Example 1, except that the material A1-1 used in Example 1 was replaced with a cyclic tetrasiloxane (A1-2) having a vinyl group as the first functional group as the cyclic siloxane (A). The obtained silicone resin composition was formed into a sheet on transparent glass so that the cured product had a thickness of 2 mm, and ultraviolet light having a wavelength of 365 nm was irradiated from the top and bottom surfaces at 3000 mJ / cm. ２ The cured product was subjected to irradiation at different temperatures to obtain a sheet-like cured product. The elongation at break (Eb) and complex modulus G were measured according to the above-mentioned measurement methods. ＊ Measurements and evaluations were carried out.

[0076] Comparative Example 1, unlike Examples 1 and 2, did not use a cyclic siloxane (A), but used a linear siloxane (a1) having multiple vinyl groups as the first functional group. This linear siloxane had an average of 4.67 mol% of vinyl-containing Si atoms relative to the number of Si atoms constituting 1 mol of the linear siloxane (model number: RH-Vi315, product of Constru Chemical Co.). The other constituent materials were the same as those used in Examples 1 and 2, and the silicone resin composition of Comparative Example 1 was obtained in the same manner as in Examples 1 and 2, except that the blending amounts of each material (a1, B1, C1, and D1) were changed to the blending amounts shown in Table 2. The ratio of the number of mercaptopropyl groups, which are second functional groups, to the total number of vinyl groups, which are first functional groups, in each component (second functional group / first functional group) was 1.1, as in Examples 1 and 2, and the amounts of each component were adjusted so that the ratio of the amount of substance of linear polymer (C) to the amount of substance of linear polysiloxane (B) [amount of substance of (C) / amount of substance of (B)] was 0.5, as in Examples 1 and 2. The resulting silicone resin composition was formed into a sheet on transparent glass so that the cured product would be 2 mm thick, and ultraviolet light having a wavelength of 365 nm was irradiated from the top and bottom surfaces at 3000 mJ / cm. ２ The cured product was subjected to irradiation at different temperatures to obtain a sheet-like cured product. The elongation at break (Eb) and complex modulus G were measured according to the above-mentioned measurement methods. ＊ Measurements and evaluations were carried out.

[0077] Example 3 In this example, the silicone resin composition of Example 3 was obtained in the same manner as in Example 1, except that the blending amounts of the materials (A1-1, B1, C1, and D1) used in Example 1 were changed to the blending amounts shown in Table 2. Furthermore, the ratio of the number of mercaptopropyl groups, which are second functional groups, to the total number of vinyl groups, which are first functional groups, in the constituent components (second functional groups / first functional groups) was 1.2, and the ratio of the amount of substance of linear polymer (C) to the amount of substance of linear polysiloxane (B) [amount of substance of (C) / amount of substance of (B)] was 0.5. A sheet-shaped cured product was prepared from this obtained silicone resin composition using the same procedure as in Example 1, and the elongation at break (Eb) and complex modulus G were measured according to the measurement methods described above. ＊ Measurements and evaluations were carried out.

[0078] Comparative Example 2 In this comparative example, a silicone resin composition of Comparative Example 2 was obtained in the same manner as in Comparative Example 1, except that the blending amounts of each material (a1, B1, C1, and D1) used in Comparative Example 1 were changed to the blending amounts shown in Table 2. The blending amounts of each component were adjusted so that the ratio of the number of mercaptopropyl groups, which are second functional groups, to the total number of vinyl groups, which are first functional groups, in each component was 1.2, as in Example 3, and the ratio of the amount of substance of linear polymer (C) to the amount of substance of linear polysiloxane (B) [amount of substance of (C) / amount of substance of (B)] was 0.5, as in Example 3. A sheet-shaped cured product was prepared from this obtained silicone resin composition using the same procedure as in Comparative Example 1, and the elongation at break (Eb) and complex modulus G were measured according to the measurement methods described above. ＊ Measurements and evaluations were carried out.

[0079] Example 4 In this example, the silicone resin composition of Example 4 was obtained in the same manner as in Example 1, except that the blending amounts of the materials (A1-1, B1, C1, and D1) used in Example 1 were changed to the blending amounts shown in Table 2. Furthermore, the ratio of the number of mercaptopropyl groups, which are second functional groups, to the total number of vinyl groups, which are first functional groups, in the constituent components (second functional groups / first functional groups) was 1.4, and the ratio of the amount of substance of linear polymer (C) to the amount of substance of linear polysiloxane (B) [amount of substance of (C) / amount of substance of (B)] was 0.5. A sheet-shaped cured product was prepared from this obtained silicone resin composition using the same procedure as in Example 1, and the elongation at break (Eb) and complex modulus G were measured according to the measurement methods described above. ＊ Measurements and evaluations were carried out.

[0080] Comparative Example 3 In this comparative example, the silicone resin composition of Comparative Example 3 was obtained in the same manner as in Comparative Example 1, except that the blending amounts of each material (a1, B1, C1, and D1) used in Comparative Example 1 were changed to the blending amounts shown in Table 2. The blending amounts of each component were adjusted so that the ratio of the number of mercaptopropyl groups, which are second functional groups, to the total number of vinyl groups, which are first functional groups, in each component was 1.4, as in Example 4, and the ratio of the amount of substance of linear polymer (C) to the amount of substance of linear polysiloxane (B) [amount of substance of (C) / amount of substance of (B)] was 0.5, as in Example 4. A sheet-shaped cured product was prepared from this obtained silicone resin composition using the same procedure as in Comparative Example 1, and the elongation at break (Eb) and complex modulus G were measured according to the measurement methods described above. ＊ Measurements and evaluations were carried out.

[0081] Examples 5 to 8 In these examples, the silicone resin compositions of Examples 5 to 8 were obtained in the same manner as in Example 1, except that the polydimethylsiloxane (C1) of the linear polymer (C) material used in Example 1 was replaced with a polydimethylsiloxane (C2) having a shorter molecular chain length, and the amounts of the materials (A1-1, B1, C2, and D1) added were changed to those shown in Table 3. In each component, the ratio of the number of mercaptopropyl groups, the second functional groups, to the total number of vinyl groups, the first functional groups (second functional groups / first functional groups) was 0.8 (Example 5), 0.9 (Example 6), 1.0 (Example 7), and 1.2 (Example 8), and the ratio of the amount of the linear polymer (C) to the amount of the linear polysiloxane (B) [amount of substance of (C) / amount of substance of (B)] was 0.5. For each of the silicone resin compositions obtained, a sheet-shaped cured product was prepared in the same manner as in Example 1, and the elongation at break (Eb) and complex modulus G were measured according to the measurement methods described above. ＊ Measurements and evaluations were carried out.

[0082] Comparative Example 4 In this comparative example, the same materials as in Comparative Example 1 were used, except that the polydimethylsiloxane (C1) of the linear polymer (C) material used in Comparative Example 1 was replaced with a polydimethylsiloxane (C2) having a shorter molecular chain length, and the amounts of the materials (a1, B1, C2, and D1) were changed to those shown in Table 3. The silicone resin composition of Comparative Example 4 was obtained in the same manner as in Comparative Example 1. Note that the ratio of the number of mercaptopropyl groups, the second functional groups, to the total number of vinyl groups, the first functional groups, in each component was 0.9, as in Example 6, and the amounts of the components were adjusted so that the ratio of the amount of substance of the linear polymer (C) to the amount of substance of the linear polysiloxane (B) [amount of substance of (C) / amount of substance of (B)] was also 0.5, as in Example 6. A sheet-shaped cured product was prepared from the obtained silicone resin composition in the same manner as in Comparative Example 1, and the elongation at break (Eb) and complex modulus G were measured according to the above-mentioned measurement methods. ＊ Measurements and evaluations were carried out.

[0083] Examples 9 to 11 In these examples, the silicone resin compositions of Examples 9 to 11 were obtained in the same manner as in Example 1, except that the polydimethylsiloxane (C1) of the linear polymer (C) material used in Example 1 was replaced with a polydimethylsiloxane (C3) having a longer molecular chain length, and the amounts of the materials (A1-1, B1, C3, and D1) were changed to those shown in Table 4. In each component, the ratio of the number of mercaptopropyl groups, the second functional groups, to the total number of vinyl groups, the first functional groups (second functional groups / first functional groups) was 1.0 (Example 9), 1.2 (Example 10), and 1.4 (Example 11), and the ratio of the amount of linear polymer (C) to the amount of linear polysiloxane (B) [amount of substance of (C) / amount of substance of (B)] was 0.5. For each of the silicone resin compositions obtained, a sheet-shaped cured product was prepared in the same manner as in Example 1, and the elongation at break (Eb) and complex modulus G were measured according to the measurement methods described above. ＊ Measurements and evaluations were carried out.

[0084] Comparative Example 5 In this comparative example, the same materials as in Comparative Example 1 were used, except that the polydimethylsiloxane (C1) of the linear polymer (C) material used in Comparative Example 1 was replaced with a polydimethylsiloxane (C3) having a longer molecular chain length, and the amounts of the materials (a1, B1, C3, and D1) were changed to those shown in Table 4. The silicone resin composition of Comparative Example 5 was obtained in the same manner as in Comparative Example 1. Note that the ratio of the number of mercaptopropyl groups, the second functional groups, to the total number of vinyl groups, the first functional groups, in each component was 1.2, as in Example 10, and the amounts of the components were adjusted so that the ratio of the amount of substance of the linear polymer (C) to the amount of substance of the linear polysiloxane (B) [amount of substance of (C) / amount of substance of (B)] was 0.5, as in Example 10. A sheet-shaped cured product was prepared from the obtained silicone resin composition in the same manner as in Comparative Example 1, and the elongation at break (Eb) and complex modulus G were measured according to the above-mentioned measurement methods. ＊ Measurements and evaluations were carried out.

[0085] Example 12 In this example, the silicone resin composition of Example 12 was obtained in the same manner as in Example 1, except that the composition was prepared without using the linear polymer (C) material used in Example 1 among the respective constituent components, and the amounts of the respective materials (A1-1, B1, and D1) were changed to the amounts shown in Table 5. The ratio of the number of mercaptopropyl groups, which are the second functional groups, to the number of vinyl groups, which are the first functional groups, in each constituent component (second functional groups / first functional groups) was 0.5. A sheet-shaped cured product was prepared from the obtained silicone resin composition using the same procedure as in Example 1, and the elongation at break (Eb) and complex modulus G were measured according to the measurement methods described above. ＊ Measurements and evaluations were carried out.

[0086] Comparative Example 6 In this comparative example, the silicone resin composition of Comparative Example 6 was prepared in the same manner as in Comparative Example 1, except that the composition was prepared without using the linear polymer (C) material used in Comparative Example 1, and the amounts of the materials (a1, B1, and D1) were changed to those shown in Table 5. The amounts of the components were adjusted so that the ratio of the number of mercaptopropyl groups, the second functional groups, to the number of vinyl groups, the first functional groups, in each component was 0.5, as in Example 12. A sheet-shaped cured product was prepared from the obtained silicone resin composition using the same procedure as in Comparative Example 1, and the elongation at break (Eb) and complex modulus G were measured according to the measurement methods described above. ＊ Measurements and evaluations were carried out.

[0087] The results of Examples 1 to 4 and Comparative Examples 1 to 3 are shown in Table 2 below, the results of Examples 5 to 8 and Comparative Example 3 are shown in Table 3 below, the results of Examples 9 to 11 and Comparative Example 5 are shown in Table 4 below, and the results of Example 12 and Comparative Example 6 are shown in Table 5 below.

[0088]

[0089]

[0090]

[0091]

[0092] The results of Examples 1 to 12 and Comparative Examples 1 to 6 revealed that the silicone resin composition of the present invention, particularly the use of "cyclic siloxane (A)" as a constituent, significantly improved the extensibility of the cured product (silicone gel). Among these, when a cyclic trisiloxane (m = 3) or a cyclic tetrasiloxane (m = 4) was used as the cyclic siloxane (A), both cyclic siloxanes exhibited high extensibility. However, the results of Examples 1 and 2 showed that the use of a cyclic trisiloxane with m = 3 in particular increased the elongation at break to a value exceeding the measurement limit, significantly improving the extensibility of the cured product. Furthermore, when the relationship between the molecular chain length (molecular weight) of the linear polymer (C) among the constituents and the elongation at break was examined, it was found that linear polymers (C) with longer molecular chain lengths (molecular weights: 28,000 and 72,000) had elongation at break that exceeded the measurement limit compared to linear polymers (C) with shorter molecular chain lengths (molecular weight: 9,400). Furthermore, when the relationship between the total molecular chain length (total molecular weight) of the linear polysiloxane (B) and the linear polymer (C) bonded between the cyclic siloxane (A) molecules among the constituent components and the elongation at break was investigated, it was found that the longer the total molecular chain length of the linear polysiloxane (B) and the linear polymer (C) (the larger the total molecular weight), the better the value of the elongation at break. More specifically, it is preferable to adjust the total molecular weight of the linear polysiloxane (B) and the linear polymer (C) to at least 20,000 or more, more preferably to adjust to 30,000 or more, and particularly preferably to adjust to 35,000 or more.

[0093] Furthermore, when the relationship between the value of [number of second functional groups / total number of first functional groups] and the elongation at break for the components of the silicone resin composition was investigated, it was found that when the total molecular chain length of the linear polysiloxane (B) and the linear polymer (C) is long (total molecular weight is large; molecular weight of component (B) is 4800, molecular weight of component (C) is 28000, 72000), it is preferable to set the [number of second functional groups / total number of first functional groups] to 1.4 or less, and particularly preferably to set it to 1 to 1.2 (Examples 1 to 4, Comparative Examples 1 to 3, Examples 9 to 11, and Comparative Example 5). On the other hand, when the total molecular chain length of the linear polysiloxane (B) and the linear polymer (C) is short (total molecular weight is small; molecular weight of component (B) is 4,800, molecular weight of component (C) is 9,400), it was found that it is preferable to set the [number of second functional groups / total number of first functional groups] to less than 1, and it is particularly preferable to set it to 0.8 or more and less than 1 (Examples 5 to 8 and Comparative Example 4).

[0094] Furthermore, the results of Example 12 and Comparative Example 6 show that the elongation at break is improved even when the silicone resin composition is composed of a cyclic siloxane (A) and a linear polysiloxane (B) without containing the linear polymer (C).

[0095] Furthermore, by using the silicone resin composition of the present invention, the complex modulus of elasticity G ＊ Regarding hardness, it showed values ​​of 7000 or more, which includes a low hardness region where the shape can be maintained to a minimum extent, and it was found that it could be adjusted over a wide range up to at least 72400, making it possible to obtain a hardened product that also has high damping properties.

[0096] The results of the above-mentioned examples show that by using the silicone resin composition of the present invention, a cured product having excellent elongation and high deformation followability can be obtained, and therefore the cured product of the present invention can be suitably used as a damping material, potting material, heat dissipation material, sealing material, coating material, vibration-proof material, vibration-damping material, and optical adhesive (OCR, OCA). Furthermore, this cured product also had an excellent complex modulus of elasticity and exhibited high damping properties, making it particularly suitable for use as a damping member.

[0097] The present invention is not limited to the above-described embodiments or examples, and various modified design forms are also included in the technical scope within the scope that does not deviate from the gist of the invention described in the claims.

[0098] The silicone resin composition of the present invention forms a cured product having high elongation, and is therefore useful as a damping material, potting material, or heat dissipation material for electric and electronic components, and is therefore widely useful in industries such as electronic devices and semiconductor devices.

Claims

1. A composition comprising: a cyclic siloxane (A) having a first functional group; a linear polysiloxane (B) having a second functional group at both ends of the molecular chain, the second functional group being capable of undergoing an addition reaction with the first functional group; a linear polymer (C) having the first functional group at both ends of the molecular chain; and a photopolymerization initiator or a thermosetting catalyst (D) that initiates or accelerates the addition reaction between the first functional group and the second functional group, wherein the cyclic siloxane (A) is a cyclic siloxane represented by the following general formula (1) or general formula (2), [In general formula (1) and general formula (2), R ａ represents the first functional group, R ｂ are each independently an alkyl group or a phenyl group, m is an integer of 3 to 5, and in general formula (2), n is an integer of 1 to 1000.] A silicone resin composition characterized in that a ratio of the number of second functional groups contained in said linear polysiloxane (B) to the total number of first functional groups contained in said cyclic siloxane (A) and said linear polymer (C) is 0.5 to 2.0, and a ratio of the amount of substance of said linear polymer (C) to the amount of substance of said linear polysiloxane (B) is 0.4 to 0.

6.

2. A composition comprising: a cyclic siloxane (A) having a first functional group; a linear polysiloxane (B) having a second functional group at both ends of the molecular chain, the second functional group being capable of undergoing an addition reaction with the first functional group; and a photopolymerization initiator or a thermosetting catalyst (D) that initiates or accelerates the addition reaction between the first functional group and the second functional group, wherein the cyclic siloxane (A) is a cyclic siloxane represented by the following general formula (1) or general formula (2), [In general formula (1) and general formula (2), R ａ represents the first functional group, R ｂ each independently represents an alkyl group or a phenyl group, m represents an integer of 3 to 5, and in general formula (2), n represents an integer of 1 to 1000.] A silicone resin composition, characterized in that a ratio of the number of second functional groups contained in said linear polysiloxane (B) to the number of first functional groups contained in said cyclic siloxane (A) is 0.5 to 2.

0.

3. The silicone resin composition according to claim 1 or 2, characterized in that one of the first functional group and the second functional group is an alkenyl group, and the other of the first functional group and the second functional group is a mercaptoalkyl group or a hydrosilyl group.

4. The silicone resin composition according to claim 3, characterized in that the cyclic siloxane (A) is a cyclic trisiloxane represented by general formula (1) or general formula (2), in which m is an integer of 3.

5. The silicone resin composition according to claim 4, wherein the first functional group is an alkenyl group, and the second functional group is a mercaptoalkyl group or a hydrosilyl group.

6. The silicone resin composition according to claim 5, wherein the alkenyl group is a vinyl group.

7. The silicone resin composition according to claim 1 or 2, further comprising at least one functional filler (E) selected from the group consisting of thixotropic fillers, thermally conductive fillers, electrically conductive fillers, magnetic fillers and dielectric fillers.

8. The silicone resin composition according to claim 1, wherein the linear polymer (C) is an organopolysiloxane represented by the following general formula (3). [In general formula (3), R ａ represents the first functional group, R ｃ each independently represents an alkyl group or a phenyl group, and p represents an integer of 30 to 2000.

9. A cured product obtained by curing the silicone resin composition according to claim 1 or 2.

10. The cured product according to claim 9, characterized in that the cured product has an elongation at break (Eb) of 200% or more (in accordance with JIS K6251:2071) and a complex modulus of elasticity of 1,000 to 100,000 (in accordance with JIS K7244-10).

11. A damping member made of the cured product according to claim 9.

12. An electronic device comprising the damping member according to claim 11.

13. A heat dissipation sheet comprising the cured product according to claim 9.

14. An electronic device equipped with the heat dissipation sheet according to claim 13.

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