Photocurable silicone composition

Abstract

To provide a photocurable silicone composition that has excellent surface curability and depth curability, and gives a cured product having small compression set.SOLUTION: A photocurable silicone composition contains (A) organopolysiloxane expressed by formula (1) (in the formula, n denotes an integer of 10 or more, R1 denotes independently a methyl group or phenyl group, R2 denotes a (meth)acryloyloxy group-containing group), (B) an organic compound that has a (meth)acryl group and an epoxy group, and does not have an alkoxysilyl group in one molecule, (C) a photoradical polymerization initiator, and (D) silica powder having a BET specific surface area of 100 m2 / g or more, where the ratio between the methyl groups bonded to silicon atoms and the phenyl groups bonded to silicon atoms in component (A) is within the range of 97:3 to 80:20.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a photocurable silicone composition that exhibits excellent surface curing and deep curing properties, provides a cured product with low compression set, and is suitable as a liquid gasket material. [Background technology]

[0002] Simplification and cost reduction in manufacturing processes are being actively promoted in various fields, overlapping with the trend toward low energy consumption with consideration for the environment. In particular, many curable elastomers used in electronic and structural parts require a high-temperature heating process for curing, which requires a huge amount of energy, time, and equipment, and therefore improvement is required. Furthermore, improvement of this heating process is significant not only in terms of energy and cost, but also in terms of manufacturing technology, as it does not damage other components.

[0003] In recent years, photocurable compositions have been attracting attention as a way to solve these problems. Photocurable compositions contain a photoinitiator that is activated by exposure to light, particularly ultraviolet light, which causes a polymerization or crosslinking reaction, and the composition cures in a short time, usually from a few tens of seconds to a few minutes. This means that it is less likely to damage other components, and does not require large facilities. Recently, ultraviolet light irradiation devices that use LEDs have been developed, making this an excellent manufacturing process.

[0004] So far, silicone compositions that use photoradical polymerization as a crosslinking system have been reported. These compositions have the characteristic of having a high reaction rate and curing in a short time due to their high reactivity, but on the other hand, the radicals have a very short life span and are easily deactivated by oxygen, etc. As a result, the curing property of the silicone composition surface that comes into contact with air can be significantly reduced. On the other hand, deep curing is also important, and a certain degree of transparency is required for the silicone composition to allow light to reach the inside.

[0005] Attempts are being made to use such photocurable compositions as liquid gasket materials. Among them, a method called cured-in-place gasket (CIPG) is suitable for gaskets that are produced in small quantities and in a wide variety of products, and is a method that makes it easy to create a cured product by irradiating light. This CIPG method involves forming a gasket material on one flange, and then pressing the other flange against it to ensure sealing. For this reason, the gasket material must not lose its restoring force even when compressed for a long period of time. In other words, low compression set is required.

[0006] As a photocurable composition characterized by low compression set, a composition containing a vinyl polymer having a (meth)acryloyl group and a compound having an ethylenically unsaturated group has been proposed, but it is insufficient in flexibility and durability compared to silicone rubber (Patent Document 1).

[0007] In order to provide two properties, namely, good surface curing property and low compression set, a silicone composition has been proposed to which fumed silica surface-treated with an organosilicon compound having a (meth)acryloyl group and an organosilicon compound not having a (meth)acryloyl group has been added (Patent Document 2). However, since a condensation reaction is used in combination with the aim of increasing the surface curing property, there is a problem in that the storage stability of the composition is reduced. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. 2007 / 004584 [Patent Document 2] JP 2018-058946 A Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made in view of the above circumstances, and has as its object to provide a photocurable silicone composition that has excellent surface curing properties and deep curing properties, and that gives a cured product with low compression set. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention provides a composition comprising the following components (A) to (D): (A) 100 parts by mass of an organopolysiloxane represented by the following general formula (1): [ka] (In the formula, n is an integer of 10 or more, and R 1 are independently a methyl group or a phenyl group, R 2 is a group represented by the following general formula (2). [ka] (In the formula, m is an integer of 0 to 20, and R 3 are independently a methyl group or a phenyl group, and Z 1 is a substituted or unsubstituted divalent organic group having 1 to 10 carbon atoms, Z 2 is an oxygen atom or a substituted or unsubstituted divalent organic group having 1 to 10 carbon atoms, and the wavy line represents a bond. (B) an organic compound having a (meth)acrylic group and an epoxy group in one molecule and no alkoxysilyl group: 0.1 to 10 parts by mass, (C) a photoradical polymerization initiator: 0.1 to 10 parts by mass, and (D)BET specific surface area 100m 2 Silica powder of / g or more: 0.1 to 50 parts by mass Contains a photocurable silicone composition, wherein the ratio of methyl groups bonded to silicon atoms to phenyl groups bonded to silicon atoms in component (A) is in the range of 97:3 to 80:20; to provide.

[0011] In such a photocurable silicone composition, the photopolymerizable reactive groups at the ends of component (A) are densely packed, resulting in good surface curability, and since the ratio of phenyl groups bonded to silicon atoms in component (A) falls within a specified range, the difference in refractive index with other components is small, making it easier for light to penetrate deeper, resulting in excellent deep curing properties.Furthermore, the resulting cured product has the characteristic of having low compression set.

[0012] The component (B) is preferably an organic compound represented by the following general formula (3). [ka] (In the formula, R 4 is a hydrogen atom or a methyl group, and Z 3 is a substituted or unsubstituted divalent organic group having 1 to 10 carbon atoms.

[0013] By including an organic compound having such a structure, good adhesion to the adherend is achieved without deteriorating the compression set.

[0014] In the present invention, the component (D) is preferably a silica powder whose surface has been treated with an organic compound having a (meth)acryloyl group.

[0015] Such a silica powder can improve shape retention without deteriorating compression set.

[0016] The present invention also provides a liquid gasket that is made from the above-mentioned photocurable silicone composition.

[0017] The photocurable silicone composition of the present invention has a cured product that has adhesive properties and exhibits low compression set, making it suitable for use as a liquid gasket material.

[0018] Furthermore, the cured product of the photocurable silicone composition of the present invention preferably has a compression set of 30% or less when measured at 120° C. and compressed by 25% for 100 hours.

[0019] In this way, the effects of the present invention can be more reliably achieved. Effect of the Invention

[0020] As described above, with the photocurable silicone composition of the present invention, the methacryl groups densely introduced at the molecular chain terminals rapidly undergo a radical polymerization reaction upon irradiation with light, making it possible not only to overcome the uncured surface portion caused by oxygen inhibition, but also to obtain a cured product with excellent deep curing properties and low compression set. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] As described above, there has been a need for the development of a photocurable silicone composition that has good surface curing properties and deep curing properties, gives a cured product with low compression set, and is useful as a liquid gasket material.

[0022] As a result of extensive research into achieving the above-mentioned object, the present inventors have discovered that a photocurable silicone composition containing an organopolysiloxane in which methacryl groups are densely arranged at the molecular chain terminals, a specific adhesion-imparting component, a photoradical polymerization initiator, and silica powder has good surface curing properties and deep curing properties, and gives a cured product with small compression set, thereby completing the present invention.

[0023] That is, the present invention provides the following components (A) to (D): (A) 100 parts by mass of an organopolysiloxane represented by the following general formula (1): [ka] (In the formula, n is an integer of 10 or more, and R 1 are independently a methyl group or a phenyl group, R 2 is a group represented by the following general formula (2). [ka] (In the formula, m is an integer of 0 to 20, and R 3are independently a methyl group or a phenyl group, and Z 1 is a substituted or unsubstituted divalent organic group having 1 to 10 carbon atoms, Z 2 is an oxygen atom or a substituted or unsubstituted divalent organic group having 1 to 10 carbon atoms, and the wavy line represents a bond. (B) an organic compound having a (meth)acrylic group and an epoxy group in one molecule and no alkoxysilyl group: 0.1 to 10 parts by mass, (C) a photoradical polymerization initiator: 0.1 to 10 parts by mass, and (D)BET specific surface area 100m 2 Silica powder of / g or more: 0.1 to 50 parts by mass Contains This is a photocurable silicone composition, characterized in that the ratio of methyl groups bonded to silicon atoms to phenyl groups bonded to silicon atoms in component (A) is in the range of 97:3 to 80:20.

[0024] The present invention will be described in detail below, but the present invention is not limited thereto.

[0025] <Component (A)> (A) An organopolysiloxane represented by the following general formula (1), which has a plurality of methacryl groups locally at the molecular chain terminals, thereby obtaining good curability. [ka]

[0026] In the above formula (1), n ​​is an integer of 10 or more, preferably 10 to 5000, and more preferably 100 to 1000. Within such a range, the composition will have good workability before curing and flexibility after curing.

[0027] Above R 1 are independently a methyl group or a phenyl group, R 2 is a group represented by the following general formula (2).

[0028] [ka]

[0029] In the above formula (2), m is an integer of 0 to 20, preferably 0 to 5, and more preferably 0 or 1. Within such a range, methacryl groups are fixed close to each other, resulting in good reactivity.

[0030] Above R 3 are independently a methyl group or a phenyl group.

[0031] Above Z 1 is a substituted or unsubstituted divalent organic group having 1 to 10 carbon atoms, examples of which include alkylene groups such as methylene, ethylene, and trimethylene, which may further contain a heteroatom such as an oxygen atom in the hydrocarbon chain. Among these, alkylene groups having 1 to 3 carbon atoms are preferred, with trimethylene being particularly preferred.

[0032] Above Z 2 is an oxygen atom or a substituted or unsubstituted divalent organic group having 1 to 10 carbon atoms, and examples of the divalent organic group having 1 to 10 carbon atoms include alkylene groups such as a methylene group, an ethylene group, and a trimethylene group. Among these, an alkylene group having 1 to 3 carbon atoms is preferred, and an ethylene group is particularly preferred.

[0033] The ratio of methyl groups bonded to silicon atoms in component (A) to phenyl groups bonded to silicon atoms is in the range of 97:3 to 80:20, and preferably in the range of 95:5 to 90:10.Within this range, the refractive index is close to that of component (C) described below, and light penetrates deeper, resulting in good deep curing properties.

[0034] The component (A) is preferably in a liquid state with a viscosity of 10 to 1,000,000 mPa·s at 25° C. The viscosity can be a value measured, for example, with a rotational viscometer.

[0035] Specific examples of component (A) are shown below. Here, C6H5 represents a phenyl group (hereinafter the same). The diorganosiloxane units may be arranged in any order. [ka]

[0036] Such organopolysiloxanes can be produced by known methods. For example, the polysiloxanes represented by the above formulas (4) and (5) can be obtained as the hydrosilylation reaction product of a dimethylsiloxane-diphenylsiloxane copolymer capped at both ends with trivinylsiloxy groups and 3-(1,1,3,3-tetramethyldisiloxanyl)propyl methacrylate (CAS No. 96474-12-3).

[0037] The polysiloxane represented by the above formula (6) can be obtained by subjecting a dimethylsiloxane-diphenylsiloxane copolymer, both ends of which are blocked with trivinylsiloxy groups, to a hydrosilylation reaction with 3-(methacryloyloxypropyl)dimethylsilane.

[0038] The polysiloxane represented by the above formula (7) can be obtained by reacting 2-hydroxyethyl methacrylate with the hydrosilylation product of a dimethylsiloxane-diphenylsiloxane copolymer capped at both ends with trivinylsiloxy groups and chlorodimethylsilane.

[0039] These components (A) may be used alone or in combination of two or more.

[0040] <(B) component> The component (B) is an organic compound that has a (meth)acrylic group and an epoxy group in one molecule, but does not have an alkoxysilyl group.

[0041] Component (B) has a photoradical reactive group, such as a methacryl group or an acrylic group, and an epoxy group that has an adhesion-imparting effect, and does not contain an alkoxysilyl group, thereby imparting adhesion to the adherend without worsening the compression set.

[0042] The component (B) is preferably an organic compound represented by the following general formula (3). [ka]

[0043] R 4 is a hydrogen atom or a methyl group, and Z 3 Z is a substituted or unsubstituted divalent organic group having 1 to 10 carbon atoms. 3 Examples of the alkylene group include alkylene groups such as methylene, ethylene and trimethylene, and these hydrocarbon chains may further contain heteroatoms such as oxygen atoms.

[0044] Specific examples of the component (B) are shown below. [ka]

[0045] These components (B) may be used alone or in combination of two or more.

[0046] The content of component (B) is 0.1 to 10 parts by mass, preferably 0.2 to 5 parts by mass, and more preferably 0.3 to 2 parts by mass, per 100 parts by mass of component (A). If the content is less than 0.1 part by mass, the adhesiveness may be poor, whereas if it exceeds 10 parts by mass, the compression set of the cured product may be large.

[0047] <(C) component> Component (C) is a photoradical polymerization initiator for promoting curing of the composition of the present invention by a radical polymerization reaction, and examples thereof include any photoradical polymerization initiator known in the art for curing acrylic functionality, such as benzoin and substituted benzoins, Michle's ketones, dialkoxyacetophenones such as diethoxyacetophenone (DEAP), benzophenone and substituted benzophenones, acetophenone and substituted acetophenones, xanthone and substituted xanthones.

[0048] Specific examples of component (C) include 2,2-diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethan-1-one (Omnirad 651, manufactured by IGM Resins BV), 1-hydroxy-cyclohexyl-phenyl-ketone (Omnirad 184, manufactured by IGM Resins BV), 2-hydroxy-2-methyl-1-phenyl-propan-1-one (Omnirad 1173, manufactured by IGM Resins BV), 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl}-2-methyl-propan-1-one (Omnirad 127, manufactured by BASF, IGM Resins BV), and phenylglyoxylic acid methyl ester (Omnirad 127, manufactured by IGM Resins BV). MBF), 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (Omnirad 907 manufactured by IGM Resins BV), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone (Omnirad 369 manufactured by IGM Resins BV), bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (Omnirad 819 manufactured by IGM Resins BV), 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (Omnirad TPO H manufactured by IGM Resins BV), and mixtures thereof.

[0049] Of the above-mentioned (C) components, from the viewpoint of compatibility with the (A) component, 2,2-diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one (Omnirad 1173 manufactured by IGM Resins BV), bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (Omnirad 819 manufactured by IGM Resins BV), and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (Omnirad TPO H manufactured by IGM Resins BV) are preferred.

[0050] The content of component (C) is 0.1 to 10 parts by mass, preferably 0.2 to 8 parts by mass, and more preferably 0.5 to 6 parts by mass, per 100 parts by mass of component (A). If the content of component (C) is less than 0.1 part by mass, the effect of promoting curing may not be obtained, whereas if it exceeds 10 parts by mass, the deep curing property of the composition may deteriorate, or the mechanical properties of the cured product may decrease.

[0051] <(D) component> (D) component has a BET specific surface area of ​​100 m 2 / g or more of silica powder, which is a component that imparts shape retention to the composition. This component ensures a thickness sufficient to maintain sealing properties when the photocurable silicone composition of the present invention is used as a liquid gasket material.

[0052] Component (D) is insoluble in components (A) to (C), and therefore may impede light transmission and reduce deep curing properties. However, by using a component with a large specific surface area, light transmission can be improved. The upper limit of the BET specific surface area is 500 m. 2 / g or less, especially 300m 2 It is preferable that the molecular weight is not more than 1 / g.

[0053] Component (D) is preferably wet silica or fumed silica, and more preferably silica that has been surface-treated with an organosilicon compound having a (meth)acryloyl group.

[0054] Specific examples of the component (D) include Carplex CS-5 and Carplex CS-7 (manufactured by Evonik Japan), Aerosil R-711 and Aerosil R-7200 (manufactured by Nippon Aerosil Co., Ltd.).

[0055] These components (D) may be used alone or in combination of two or more.

[0056] The amount of component (D) is 0.1 to 50 parts by mass, preferably 1 to 30 parts by mass, and more preferably 3 to 20 parts by mass, per 100 parts by mass of component (A). If the amount of component (D) is less than 0.1 part by mass, it may not be possible to impart the desired shape retention to the composition, whereas if it exceeds 50 parts by mass, the deep section curing properties of the composition may deteriorate.

[0057] <Other ingredients> Depending on the purpose, the composition of the present invention may contain other components such as an adhesion improver other than the component (B) and a radical reaction inhibitor.

[0058] As the adhesion improver other than component (B), there may be used organosilicon compounds such as silanes and siloxanes, which contain functional groups that impart adhesion, and non-silicone organic compounds.

[0059] More specifically, those which do not simultaneously contain a radical reactive group and an alkoxysilyl group in one molecule are preferred, and examples thereof include trialkyl-isocyanurate or triallyl-isocyanurate, and glycidoxypropyltrimethoxysilane.

[0060] Examples of the radical reaction inhibitor include phenol-based radical reaction inhibitors such as dibutylhydroxytoluene (BHT) and amine-based radical reaction inhibitors such as diphenylamine derivatives.

[0061] <Photocurable silicone composition> The photocurable silicone composition of the present invention contains the above-mentioned components (A) to (D), and, if necessary, other components.

[0062] The method for preparing the photocurable silicone composition of the present invention is not particularly limited, and can be carried out by mixing, stirring, and dispersing the above-mentioned components. The equipment for mixing, stirring, dispersing, etc. is not particularly limited, but a mortar and pestle machine equipped with a stirring and heating device, a three-roll mill, a ball mill, a planetary mixer, a bead mill, etc. can be used. These equipments may also be used in appropriate combination.

[0063] <Liquid gasket> The photocurable silicone composition of the present invention has high reactivity, and when irradiated with the necessary light, it cures well even in air, and furthermore, the compression set of the cured product is small, making it useful as a liquid gasket. It is particularly useful for the CIPG method, in which a liquid gasket material is applied to one flange, cured and bonded by irradiation with light, and then the other flange is pressed against it to ensure sealing.

[0064] <Cured product> The photocurable silicone composition of the present invention cures rapidly when irradiated with ultraviolet light.

[0065] In this case, examples of light sources for the ultraviolet light to be irradiated include UV-LED lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, carbon arc lamps, and xenon lamps, and those that emit light with a wavelength in the range of 220 to 400 nm can be suitably used.

[0066] The UV irradiation intensity is 30 to 2,000 mW / cm 2 is preferable, and the irradiation amount (accumulated light amount) is 150 to 10,000 mJ / cm 2 The temperature during irradiation is preferably 10 to 60°C, and more preferably 20 to 40°C.

[0067] The cured product obtained by curing the photocurable silicone composition of the present invention preferably has a compression set of 30% or less when measured after 100 hours at 120° C. and 25% compression. Such a cured product is particularly useful as a liquid gasket. EXAMPLES

[0068] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. The abbreviations representing the respective siloxane units are as follows.

[0069] [ka]

[0070] [Examples 1 to 5, Comparative Examples 1 to 5] A photocurable silicone composition was prepared by mixing the following components in the amounts shown in Table 1. The numerical values ​​for each component in Table 1 are in parts by mass unless otherwise specified. The numbers in parentheses for component (A) indicate the ratio of methyl groups bonded to silicon atoms and phenyl groups bonded to silicon atoms in component (A). (A) Component: (A-1)M 3MA -1Unit:DUnit:D 2Φ Organopolysiloxane (methyl group:phenyl group=90:10) with a ratio of 2:390:43 and a viscosity of 10 Pa s at 25°C. (A-2)M 3MA -2 Unit: D Unit: D 2Φ Organopolysiloxane (methyl group:phenyl group=90:10) with a ratio of 2:390:43 and a viscosity of 10 Pa s at 25°C. (A-3)M 3MA -1Unit:DUnit:D 2Φ Organopolysiloxane (methyl group:phenyl group=95:5) with a ratio of 2:370:22 and a viscosity of 5 Pa s at 25°C. (A'-4)M 3MA An organopolysiloxane (methyl group:phenyl group=100:0) with a ratio of -1 unit:D unit=2:530 and a viscosity of 10 Pa s at 25°C. (A'-5)M MA Unit: DUnit: D 2Φ Organopolysiloxane (methyl group:phenyl group=90:10) with a ratio of 2:390:43 and a viscosity of 10 Pa s at 25°C. (A'-6)M 2A Unit: DUnit: D 2Φ Organopolysiloxane (methyl group:phenyl group=90:10) with a ratio of 2:390:43 and a viscosity of 10 Pa s at 25°C.

[0071] (B component): (B-1) 4-Hydroxybutyl acrylate glycidyl ether (B-2) Glycidyl acrylate (B'-3) 3-Methacryloxypropyltrimethoxysilane

[0072] (Component C): 2-hydroxy-2-methyl-1-phenyl-propan-1-one (Omnirad 1173 manufactured by IGM Resins BV)

[0073] (D) Ingredients: (D-1) Aerosil R-711 (manufactured by Nippon Aerosil Co., Ltd., methacryloylsilane-treated fumed silica, BET specific surface area 150 m 2 / g) (D-2) Carplex CS-5 (Evonik Japan, wet silica, BET specific surface area 130 m 2 / g)

[0074] [Table 1]

[0075] The photocurable silicone compositions obtained in Examples 1 to 5 and Comparative Examples 1 to 5 in Table 1 were evaluated for surface curability, deep curability, hardness, adhesion, and compression set as described below. The results are shown in Table 2. UV irradiation was performed using a lamp H(M)06-L-61 manufactured by Eye Graphics Co., Ltd. at 7,500 mJ / cm in air at 25°C. 2 The irradiation was performed at a dose of .

[0076] [Surface hardening] The composition was poured into a mold to a thickness of 10 mm and irradiated with ultraviolet light from one side. If the surface of the irradiated side was hardened, it was rated as "good," and if even a part of it was liquid, it was rated as "poor."

[0077] [Deep hardenability] The composition was poured into a mold to a thickness of 10 mm, and when it was irradiated with ultraviolet light from one side, if the surface opposite the irradiated side had hardened it was rated as "good", and if even a part of it was liquid it was rated as "bad".

[0078] [Hardness] The composition was irradiated with ultraviolet light to produce a cured product having a thickness of 6.0 mm. The hardness immediately after curing was measured in an environment of 25° C. using a durometer type A hardness tester.

[0079] [Adhesiveness] The composition was dropped onto a stainless steel plate, irradiated with ultraviolet light, and then left to stand for 24 hours in an environment of 25°C before the cured product was peeled off and tested. If the cured product underwent cohesive failure, it was rated as "adhesion", and if it peeled off at the interface, it was rated as "peeling".

[0080] [Compression set] The composition was irradiated with ultraviolet light to produce a cured product with a thickness of 4 mm and a diameter of 25 mm. Three of these were stacked (the thickness at this point was designated as t0), compressed to 9 mm, and held at 120°C for 100 hours. After compression, the thickness t was measured after leaving the material to stand at 23°C for 30 minutes, and the compression set (%) was calculated using the following formula. (t0-t) / (t0-9.00)×100

[0081] [Table 2]

[0082] As shown in Table 2, the photocurable silicone compositions of Examples 1 to 5 exhibited excellent surface curability and deep curability, exhibited good adhesion, and exhibited small compression set in the cured product.

[0083] On the other hand, in Comparative Example 1, in which the (A) component was changed to an organopolysiloxane with a small content of phenyl groups bonded to silicon atoms, the surface curing properties and deep curing properties were inferior. In Comparative Example 2, in which the (A) component was changed to an organopolysiloxane with a small number of terminal functional groups, the surface curing properties were deteriorated. In Comparative Example 3, in which the (A) component was changed to an organopolysiloxane with an acrylic terminal functional group, and in Comparative Example 4, in which the (B) component was changed to a compound without an epoxy group, the compression set of the cured product was large, and in Comparative Example 5, in which the (B) component was not included, no adhesion was exhibited.

[0084] In this way, the present invention is able to provide a photocurable silicone composition that has excellent surface curing properties and deep curing properties, and that gives a cured product that has good adhesive properties and small compression set.

[0085] The present invention includes the following aspects. The following components (A) to (D): [1]: (A) an organopolysiloxane represented by the following general formula (1): 100 parts by mass, [ka] (In the formula, n is an integer of 10 or more, and R 1 are independently a methyl group or a phenyl group, R 2 is a group represented by the following general formula (2). [ka] (In the formula, m is an integer of 0 to 20, and R 3 are independently a methyl group or a phenyl group, and Z 1 is a substituted or unsubstituted divalent organic group having 1 to 10 carbon atoms, Z 2 is an oxygen atom or a substituted or unsubstituted divalent organic group having 1 to 10 carbon atoms, and the wavy line represents a bond. (B) an organic compound having a (meth)acrylic group and an epoxy group in one molecule and no alkoxysilyl group: 0.1 to 10 parts by mass, (C) a photoradical polymerization initiator: 0.1 to 10 parts by mass, and (D)BET specific surface area 100m 2 Silica powder of / g or more: 0.1 to 50 parts by mass Contains A photocurable silicone composition, wherein the ratio of methyl groups bonded to silicon atoms to phenyl groups bonded to silicon atoms in component (A) is within the range of 97:3 to 80:20. [2]: The photocurable silicone composition according to the above [1], wherein the component (B) is an organic compound represented by the following general formula (3): [ka] (In the formula, R 4 is a hydrogen atom or a methyl group, and Z 3 is a substituted or unsubstituted divalent organic group having 1 to 10 carbon atoms. [3]: The photocurable silicone composition according to the above [1] or [2], wherein the component (D) is a silica powder that has been surface-treated with an organosilicon compound having a (meth)acryloyl group. [4]: A liquid gasket comprising the photocurable silicone composition according to any one of the above [1] to [3]. [5]: A cured product of the photocurable silicone composition according to any one of [1] to [3] above, characterized in that the cured product has a compression set of 30% or less when measured after 100 hours at 120°C and 25% compression.

[0086] The present invention is not limited to the above-described embodiment. The above-described embodiment is merely an example, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits similar effects is included in the technical scope of the present invention.

Claims

1. The following components (A) to (D): (A) 100 parts by mass of an organopolysiloxane represented by the following general formula (1): 【Chemistry 1】 (In the formula, n is an integer of 10 or more, and R １ are independently a methyl group or a phenyl group, R ２ is a group represented by the following general formula (2): 【Chemistry 2】 (In the formula, m is an integer from 0 to 20, and R ３ are independently a methyl group or a phenyl group; Z １ is a substituted or unsubstituted divalent organic group having 1 to 10 carbon atoms; Z ２ is an oxygen atom or a substituted or unsubstituted divalent organic group having 1 to 10 carbon atoms, and the wavy line represents a bond. (B) an organic compound having a (meth)acrylic group and an epoxy group in one molecule and having no alkoxysilyl group: 0.1 to 10 parts by mass, (C) a photoradical polymerization initiator: 0.1 to 10 parts by mass, and (D) BET specific surface area 100m ２ / g or more silica powder: 0.1 to 50 parts by mass Contains A photocurable silicone composition, wherein the ratio of methyl groups bonded to silicon atoms to phenyl groups bonded to silicon atoms in component (A) is in the range of 97:3 to 80:

20.

2. 2. The photocurable silicone composition according to claim 1, wherein the component (B) is an organic compound represented by the following general formula (3): 【Chemistry 3】 (In the formula, R ４ is a hydrogen atom or a methyl group, Z ３ is a substituted or unsubstituted divalent organic group having 1 to 10 carbon atoms.

3. 2. The photocurable silicone composition according to claim 1, wherein component (D) is a silica powder that has been surface-treated with an organosilicon compound having a (meth)acryloyl group.

4. A liquid gasket comprising the photocurable silicone composition according to any one of claims 1 to 3.

5. 4. A cured product of the photocurable silicone composition according to any one of claims 1 to 3, characterized in that the cured product has a compression set of 30% or less when measured after 100 hours at 120°C and 25% compression.