Photocurable silicone composition

Abstract

The present invention provides a photocurable silicone composition characterized by containing (A) an organopolysiloxane represented by general formula (1) (in the formula, n is an integer of 10 or more, R1 is independently a methyl group or a phenyl group, and R2 is a group represented by general formula (2)): (A) an organopolysiloxane represented by general formula (1) (in the formula, n is an integer of 10 or more, R1 is independently a methyl group or a phenyl group, and R2 is a group represented by general formula (2)). [Chemical Formula 2] (In the formula, m is an integer of 0-20, R3 is independently a methyl group or a phenyl group, Z1 is a substituted or unsubstituted divalent organic group having 1-10 carbon atoms, Z2 is an oxygen atom or a substituted or unsubstituted divalent organic group having 1-10 carbon atoms, and a wavy line represents a bond) The present invention relates to a composition comprising (A) an organic compound having a (meth) acryloyl group and an epoxy group in one molecule and not having an alkoxysilyl group, (B) an organic compound having a (meth) acryloyl group and an epoxy group in one molecule and not having an alkoxysilyl group, (C) a photo-radical polymerization initiator, and (D) a silica powder having a BET specific surface area of 100 m2 / g or more, the composition being characterized in that the ratio of a methyl group bonded to a silicon atom to a phenyl group bonded to a silicon atom in component (A) is in the range of 97: 3 to 80: 20. As a result, provided is a photocurable silicone composition with which a cured product having excellent surface curability and deep curability and small compression set can be obtained.

Description

Technical Field

[0001] This invention relates to a photocurable silicone composition that yields a cured product with good surface and deep curing properties and low compression set, making it suitable as a liquid gasket material. Background Technology

[0002] The simplification and cost reduction of manufacturing processes align with the trend towards environmentally friendly energy conservation, and are being actively promoted in various fields. In particular, the curing of curable elastomers used in electronic and structural components often involves high-temperature heating processes, requiring significant energy, time, and equipment; therefore, improvements are desired. Furthermore, improvements to this heating process are not only significant in terms of energy and cost, but also in terms of manufacturing techniques that prevent damage to other components.

[0003] In recent years, photocurable compositions have attracted much attention in order to solve these problems. Photocurable compositions contain photoinitiators activated by light, particularly ultraviolet light, which then undergo polymerization or cross-linking reactions, typically curing within a short time of tens of seconds to tens of minutes. Therefore, they are less likely to damage other components and do not require large equipment. Recently, ultraviolet irradiation devices utilizing LEDs have also been developed, becoming an excellent manufacturing process.

[0004] To date, organosilicon compositions using photoradical polymerization as a crosslinking system have been reported. These compositions exhibit rapid reaction rates due to their high reactivity, resulting in curing within a short time. Conversely, free radicals have very short lifetimes and are easily deactivated by oxygen and other substances. Consequently, the curability of the organosilicon composition's surface exposed to air may be significantly reduced. On the other hand, deep curing is also important; to allow light to reach the interior, the organosilicon composition needs a certain degree of transparency.

[0005] Currently, there are attempts to apply such photocurable compositions to liquid gasket materials. One method, known as in-situ cured gasket (CIPG), is suitable for producing small batches of diverse gaskets and is a method that easily creates cured materials through light irradiation. CIPG involves forming the gasket material on one flange and then pressing it against the other flange to ensure a seal. Therefore, the gasket material must maintain its resilience even after prolonged compression; that is, it needs to have low compressive strength.

[0006] As a photocurable composition with low compression set, compositions comprising ethylene polymers having (meth)acryloyl groups and compounds having olefinic unsaturated groups have been proposed, but they are still inferior to silicone rubber in terms of softness and durability (Patent Document 1).

[0007] To achieve good surface curability and low compression set, a silicone composition containing fumigated silica surface-treated with both (meth)acryloyl-containing and (non-meth)acryloyl-containing silicone compounds has been proposed (Patent Document 2). However, the composition suffers from reduced shelf life due to the simultaneous condensation reaction performed to improve surface curability. Existing technical documents Patent documents

[0008] Patent Document 1: International Publication No. 2007 / 004584 Patent Document 2: Japanese Patent Application Publication No. 2018-058946 Summary of the Invention The technical problem that the invention aims to solve

[0009] The present invention was made in view of the above circumstances, and its object is to provide a photocurable organosilicon composition that yields a cured product with excellent surface curing and deep curing properties and low compression set. Technical means to solve the problem

[0010] To address the aforementioned problems, this invention provides a photocurable organosilicon composition, characterized in that... It contains the following components (A) to (D); (A) An organopolysiloxane represented by the following general formula (1): 100 parts by mass, [Chemical Formula 1] (In the formula, n is an integer greater than or equal to 10, R) １ Independently methyl or phenyl, R 2 (This refers to a group represented by the following general formula (2).) [Chemical Formula 2] (In the formula, m is an integer from 0 to 20, R) 3 Independently methyl or phenyl, Z 1 Z is a divalent organic group with 1 to 10 carbon atoms, either substituted or unsubstituted. 2 (A divalent organic group consisting of 1 to 10 carbon atoms, either with an oxygen atom or with substituted or unsubstituted carbon atoms; the wavy line indicates a bond.) (B) Organic compounds having a (meth)acryloyl group and an epoxy group in one molecule but not an alkoxysilyl group: 0.1 to 10 parts by weight, (C) Photoradical polymerization initiator: 0.1–10 parts by weight, and (D) BET specific surface area 100m² 20.1 to 50 parts by weight of silica powder with a density of 1 g or higher. Furthermore, 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.

[0011] In such a photocurable silicone composition, the surface curing properties are excellent due to the dense photopolymerizable reactive groups at the ends of component (A). Furthermore, the ratio of phenyl groups bonded to silicon atoms in component (A) meets the specified range, reducing the refractive index difference between it and other components, allowing light to easily penetrate deeper, thus resulting in excellent deep curing properties. Additionally, it exhibits the characteristic of low compression set in the resulting cured product.

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

[0013] Organic compounds containing such a structure do not deteriorate compression set and adhere well to the substrate.

[0014] In this invention, the above-mentioned component (D) is preferably silica powder that has been surface-treated with an organosilicon compound having (meth)acryloyl groups.

[0015] If it is silica powder of this type, it will not worsen compression set and will improve shape retention.

[0016] In addition, the present invention can provide a liquid pad made of the above-described photocurable silicone composition.

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

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

[0019] If such a substance is used, the effects of the present invention can be achieved more reliably. Invention Effects

[0020] As described above, in the case of the photocurable silicone composition of the present invention, since the methacryloyl groups densely introduced at the ends of the molecular chain rapidly induce a free radical polymerization reaction under light irradiation, it is possible not only to overcome the uncured surface portion caused by oxygen hindrance, but also to obtain a cured product with excellent deep curing properties and small compression set. Detailed Implementation

[0021] As described above, there is a need to develop a photocurable silicone composition that is useful as a liquid gasket material, and to obtain a cured product with good surface curing and deep curing properties and low compression set.

[0022] The inventors conducted in-depth research to achieve the above objectives and discovered that a photocurable silicone composition containing a methacryloyl group densely arranged at the end of the molecular chain, a specific adhesive-improving component, a photoradical polymerization initiator, and silica powder can produce a cured product with good surface curing and deep curing properties and low compression set, thus completing the present invention.

[0023] That is, the present invention is a photocurable organosilicon composition, characterized in that, It contains the following components (A) to (D); (A) An organopolysiloxane represented by the following general formula (1): 100 parts by mass, [Chemical Formula 4] (In the formula, n is an integer greater than or equal to 10, R) 1 Independently methyl or phenyl, R 2 (This refers to a group represented by the following general formula (2).) [Chemical Formula 5] (In the formula, m is an integer from 0 to 20, R) 3 Independently methyl or phenyl, Z 1 Z is a divalent organic group with 1 to 10 carbon atoms, either substituted or unsubstituted. 2 It is a divalent organic group with 1 to 10 carbon atoms, either with oxygen atoms or with substituted or unsubstituted atoms. The wavy line indicates a bond. (B) Organic compounds having a (meth)acryloyl group and an epoxy group in one molecule but not an alkoxysilyl group: 0.1 to 10 parts by weight, (C) Photoradical polymerization initiator: 0.1–10 parts by weight, and (D) BET specific surface area 100m² 2 0.1 to 50 parts by weight of silica powder with a density of 1 g or higher. Furthermore, 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 now be described in detail, but the invention is not limited thereto.

[0025] <(A) Ingredient> (A) The organopolysiloxane represented by the following general formula (1) can achieve good curability by having multiple methacrylamide groups locally at the ends of the molecular chain. [Chemical Formula 6]

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

[0027] The above R 1 Independently methyl or phenyl, R 2 The group is represented by the following general formula (2).

[0028] [Chemical Formula 7]

[0029] In the above formula (2), m is an integer from 0 to 20, preferably from 0 to 5, and more preferably 0 or 1. If it is within such a range, good reactivity can be achieved because the methacryloyl groups are tightly fixed to each other.

[0030] The above R 3 It can be methyl or phenyl on its own.

[0031] The above Z 1 The hydrocarbon chain may contain a substituted or unsubstituted divalent organic group having 1 to 10 carbon atoms. Examples of alkylene groups include methylene, ethylene, and trimethylene. Furthermore, these hydrocarbon chains may also contain heteroatoms such as oxygen atoms. Among these, alkylene groups having 1 to 3 carbon atoms are preferred, and trimethylene is particularly preferred.

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

[0033] (A) The ratio of methyl groups bonded to silicon atoms to phenyl groups bonded to silicon atoms is in the range of 97:3 to 80:20, preferably in the range of 95:5 to 90:10. If it is in this range, the refractive index is close to that of (C) as described later, and light can penetrate to a deeper depth, thus achieving good deep curing properties.

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

[0035] The following shows a specific example of component (A). Here, C6H5 represents a phenyl group (the same applies below). Furthermore, the arrangement of the diorganosiloxane units can be arbitrary. [Chemical Formula 8]

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

[0037] The polysiloxane represented by the above formula (6) can be obtained by hydrosilylation of 3-(methacryloyloxypropyl)dimethylsilane with a two-terminated trivinylsiloxy-terminated dimethylsiloxane-diphenylsiloxane copolymer.

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

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

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

[0041] (B) The component is a component that has a methacryloyl or acryloyl group as a photoradical reactive group, an epoxy group that imparts an adhesive effect, and does not contain alkoxysilyl groups, which does not degrade compression set and imparts adhesiveness to the bonded material.

[0042] (B) The preferred component is an organic compound represented by the following general formula (3). [Chemical Formula 9]

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

[0044] The following are specific examples of component (B). [Chemical Formula 10]

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

[0046] The content of component (B) relative to 100 parts by mass of component (A) 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. If it is less than 0.1 parts by mass, the adhesion may be poor; if it is more than 10 parts by mass, the compression set of the cured material may be large.

[0047] <(C) Component> (C) is a photoradical polymerization initiator used to promote the curing of the composition of the present invention by a free radical polymerization reaction. Examples include any photoradical polymerization initiator known in the art that cures acryloyl functional groups, such as benzoin and substituted benzoin, Michler's ketone, diethoxyacetophenone (DEAP) and other diethoxyacetophenones, benzophenone and substituted benzophenones, acetophenone and substituted acetophenones, xanthonone and substituted xanthonones.

[0048] Specific examples of component (C) include 2,2-diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one (Omnirad 651 manufactured by IGM Resins BV), 1-hydroxy-cyclohexyl-phenyl-methyl ketone (Omnirad 184 manufactured by IGM Resins BV), 2-hydroxy-2-methyl-1-phenyl-1-propane-1-one (Omnirad 1173 manufactured by IGM Resins BV), 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propanoyl)-benzyl]-phenyl}-2-methyl-propane-1-one (Omnirad 127 manufactured by IGM Resins BV), and methyl benzoylformate (Omnirad 127 manufactured by IGM Resins BV). MBF), 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1-one (Omnirad 907 manufactured by IGM Resins B.V.), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone (Omnirad 369 manufactured by IGM Resins B.V.), 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] From the viewpoint of compatibility with component (A), the preferred components in component (C) are 2,2-diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-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).

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

[0051] <(D) component> (D) The component has a BET specific surface area of ​​100m². 2The silica powder at a concentration of / g or higher is a component that imparts shape retention to the composition. This component ensures the thickness required to maintain a seal when the photocurable silicone composition of the present invention is used as a liquid gasket material. It should be noted that the BET specific surface area is a value measured according to JIS Z8830:2013 standard using a Macsorb (registered trademark) HM Model-1201 manufactured by Mounttech Co., Ltd.

[0052] Component (D) is insoluble in components (A) to (C), thus hindering light transmission and potentially reducing deep curing properties. However, by using a material with a larger specific surface area, light transmittance can be improved. It should be noted that the upper limit of the BET specific surface area is preferably 500 m². 2 / g or less, especially preferably 300m 2 / g or less.

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

[0054] Specific examples of component (D) include Caplux CS-5, Caplux CS-7 (manufactured by Evonik Industries, Inc. of Japan), and AEROSIL R-711 and AEROSIL R-7200 (manufactured by AEROSIL Corporation of Japan).

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

[0056] The amount of component (D) is equivalent to 100 parts by weight of component (A), ranging from 0.1 to 50 parts by weight, preferably from 1 to 30 parts by weight, and more preferably from 3 to 20 parts by weight. If the amount of component (D) is less than 0.1 parts by weight, the desired shape retention may not be imparted to the composition, and if it exceeds 50 parts by weight, the deep curing properties of the composition may sometimes deteriorate.

[0057] <Other Ingredients> In the composition of the present invention, adhesiveness improvers, free radical reaction inhibitors, and other components other than component (B) may be added, depending on the purpose.

[0058] As an adhesiveness enhancer other than component (B), organosilicon compounds such as silanes and siloxanes, or non-organosilicon organic compounds, containing functional groups that impart adhesiveness can be used.

[0059] More specifically, it is preferable that a single molecule does not simultaneously contain a radical reactive group and an alkoxysilane, for example, trialkyl isocyanurate or triallyl isocyanurate, glycidoxypropyltrimethoxysilane, etc.

[0060] Examples of free radical reaction inhibitors include phenolic free radical reaction inhibitors such as butylated hydroxytoluene (BHT) and amine free radical reaction inhibitors such as diphenylamine derivatives.

[0061] <Photocurable Organosilicon Composition> The photocurable silicone composition of the present invention comprises the above-mentioned components (A) to (D) and other components as needed.

[0062] The preparation method of 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. There are no particular limitations on the mixing, stirring, and dispersing apparatus, but high-speed dispersers, three-roll mills, ball mills, planetary mixers, bead mills, etc., equipped with stirring and heating devices can be used. Furthermore, these apparatuses can be used in appropriate combinations.

[0063] <Liquid Gasket> The photocurable silicone composition of the present invention is highly reactive and can be well cured in air by necessary light irradiation, and the cured product has low compression set, making it useful as a liquid gasket. In particular, there is a CIPG method for ensuring a seal by applying liquid gasket material to one flange, curing and bonding it by light irradiation, and then pressing the other flange.

[0064] <Cured product> The photocurable silicone composition of the present invention is rapidly cured by irradiation with ultraviolet light.

[0065] In this case, the light source for irradiating ultraviolet light can include, for example, UV-LED lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, carbon arc lamps, xenon lamps, etc., and a light source containing light in the wavelength range of 220 to 400 nm can be used appropriately.

[0066] The preferred intensity of ultraviolet radiation is 30–2,000 mW / cm². 2 The preferred irradiation dose (cumulative light intensity) is 150–10,000 mJ / cm². 2 The irradiation temperature is preferably 10–60°C, more preferably 20–40°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 after being compressed at 25% for 100 hours at 120°C. Such a cured product is particularly useful as a liquid gasket. [Example]

[0068] The following examples and comparative examples illustrate the present invention in detail, but the present invention is not limited to the following examples. It should be noted that the abbreviations representing each siloxane unit are shown below.

[0069] [Chemical Formula 11]

[0070] [Examples 1-5, Comparative Examples 1-5] A photocurable silicone composition was prepared by mixing the following components in the proportions shown in Table 1. It should be noted that, unless otherwise stated, the values ​​for each component in Table 1 represent parts by mass. The brackets for component (A) indicate the ratio of methyl groups bonded to silicon atoms to phenyl groups bonded to silicon atoms in component (A). (A) Ingredients: (A-1)M 3MA -1 Unit: D Unit: D 2Φ Organopolysiloxane (methyl:phenyl = 90:10) with a unit 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:phenyl = 90:10) with a unit ratio of 2:390:43 and a viscosity of 10 Pa·s at 25°C. (A-3)M 3MA -1 Unit: D Unit: D 2Φ Organopolysiloxane (methyl:phenyl = 95:5) with a unit ratio of 2:370:22 and a viscosity of 5 Pa·s at 25°C. (A'-4)M 3MA Organopolysiloxane (methyl:phenyl = 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: D 2Φ Organopolysiloxane (methyl:phenyl = 90:10) with a unit ratio of 2:390:43 and a viscosity of 10 Pa·s at 25°C. (A'-6)M 2A Unit: D 2Φ Organopolysiloxane (methyl:phenyl = 90:10) with a unit ratio of 2:390:43 and a viscosity of 10 Pa·s at 25°C.

[0071] (Component B): (B-1) 4-Hydroxybutylacrylate glycidyl ether (B-2) Glycidyl acrylate (B'-3)3-Methacryloyloxypropyltrimethoxysilane

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

[0073] (D) Ingredients: (D-1) AEROSIL R-711 (manufactured by AEROSIL Corporation of Japan, methacryloylsilane treated fuzzy silica, BET specific surface area 150m²) 2 / g) (D-2) Caplux CS-5 (manufactured by Evonik Industries, Japan, wet silica, BET specific surface area 130m²) 2 / g)

[0074] [Table 1]

[0075] The photocurable silicone compositions obtained in Examples 1-5 and Comparative Examples 1-5 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. It should be noted that ultraviolet irradiation was performed using a lamp H(M)06-L-61 manufactured by EYE Graphics Co., Ltd., at 7,500 mJ / cm² in air at 25°C. 2 The amount of radiation was determined.

[0076] [Surface curing properties] Pour the composition into a mold to a thickness of 10 mm. After irradiating one side with ultraviolet light, the surface that has solidified on the irradiated side is recorded as "good" and the surface that is still partially liquid is recorded as "bad".

[0077] [Deep curing properties] Pour the composition into a mold to make it 10 mm thick. When irradiating it with ultraviolet light from one side, the state of the surface opposite the irradiated side that has solidified is recorded as "good", and the state where any part is still liquid is recorded as "bad".

[0078] [hardness] A cured product with a thickness of 6.0 mm was prepared by irradiating the composition with ultraviolet light. The hardness was measured immediately after curing using a Shore A hardness tester at 25°C.

[0079] [Adhesiveness] The composition was dropped onto an SUS plate, irradiated with ultraviolet light, and then the cured material, which had been left to stand at 25°C for 24 hours, was peeled off and tested. The state in which the cured material agglomerated and broke down was recorded as "adhesion," and the state in which the interface peeled off was recorded as "peeling."

[0080] [Compression permanent deformation] The composition was irradiated with ultraviolet light to prepare a cured material with a thickness of 4 mm and a diameter of 25 mm. Three layers of this material were stacked together (the thickness at this point is denoted as t0), compressed to 9 mm, and held at 120°C for 100 hours. After compression, the thickness t was measured after standing 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 1-5 exhibit good surface curing and deep curing properties, as well as good adhesion and low compression set of the cured product.

[0083] On the other hand, in Comparative Example 1, where component (A) was changed to an organopolysiloxane with a lower content of phenyl groups bonded to silicon atoms, both surface curing and deep curing properties deteriorated. Furthermore, in Comparative Example 2, where component (A) was changed to an organopolysiloxane with fewer terminal functional groups, surface curing properties worsened. In Comparative Example 3, where component (A) was changed to an organopolysiloxane with acryloyl terminal functional groups, and in Comparative Example 4, where component (B) was changed to a compound without epoxy groups, the compression set of the cured product was large. In Comparative Example 5, which did not contain component (B), no adhesion was observed.

[0084] As described above, the present invention provides a photocurable silicone composition that produces a cured product with excellent surface and deep curing properties, good adhesion, and low compression set.

[0085] The present invention includes the following methods. A photocurable organosilicon composition, characterized in that, It contains the following components (A) to (D); [1]: (A) an organopolysiloxane represented by the following general formula (1): 100 parts by mass, [Chemical Formula 12] (In the formula, n is an integer greater than or equal to 10, R) 1 Independently methyl or phenyl, R 2(This refers to a group represented by the following general formula (2).) [Chemical Formula 13] (In the formula, m is an integer from 0 to 20, R) 3 Independently methyl or phenyl, Z 1 Z is a divalent organic group with 1 to 10 carbon atoms, either substituted or unsubstituted. 2 (A divalent organic group consisting of 1 to 10 carbon atoms, either with an oxygen atom or with substituted or unsubstituted atoms; the wavy line indicates a bond.) (B) Organic compounds having a (meth)acryloyl group and an epoxy group in one molecule but not an alkoxysilyl group: 0.1 to 10 parts by weight, (C) Photoradical polymerization initiator: 0.1–10 parts by weight, and (D) BET specific surface area 100m² 2 0.1 to 50 parts by weight of silica powder with a density of 1 g or higher. Furthermore, 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]: The photocurable organosilicon composition according to [1] above is characterized in that the (B) component is an organic compound represented by the following general formula (3). [Chemical Formula 14] (In the formula, R) 4 Z represents a hydrogen atom or a methyl group. 3 (A divalent organic group having 1 to 10 carbon atoms, either substituted or unsubstituted.) [3]: The photocurable organosilicon composition according to [1] or [2] above is characterized in that the (D) component is silica powder that has been surface-treated with an organosilicon compound having (meth)acryloyl groups. [4]: A liquid pad, characterized in that it is composed of any one of the above-mentioned [1] to [3] photocurable organosilicon compositions. [5]: The cured product of the photocurable organosilicon composition described in any one of [1] to [3] above is characterized in that the compression set measured after being compressed at 25% for 100 hours at 120°C is less than 30%.

[0086] It should be noted that the present invention is not limited to the above-described embodiments. The above embodiments are illustrative examples, and any technical solutions having a substantially the same structure and achieving the same effect as the technical concept described in the claims of the present invention are included within the protection scope of the present invention.

Claims

1. A photocurable organosilicon composition, characterized in that, It contains the following components (A) to (D); (A) An organopolysiloxane represented by the following general formula (1): 100 parts by mass, [Chemical Formula 1] In the formula, n is an integer greater than or equal to 10, and R 1 Independently methyl or phenyl, R 2 For groups represented by the following general formula (2), [Chemical Formula 2] In the formula, m is an integer from 0 to 20, and R 3 Independently methyl or phenyl, Z 1 Z is a divalent organic group with 1 to 10 carbon atoms, either substituted or unsubstituted. 2 These are divalent organic groups consisting of 1 to 10 carbon atoms, either with an oxygen atom or with substituted or unsubstituted carbon atoms. The wavy lines indicate bonding bonds. (B) Organic compounds having a (meth)acryloyl group and an epoxy group in one molecule but not an alkoxysilyl group: 0.1 to 10 parts by weight, (C) Photoradical polymerization initiator: 0.1–10 parts by weight, and (D) BET specific surface area 100m² 2 0.1 to 50 parts by weight of silica powder with a density of 1 g or higher. Furthermore, 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. The photocurable organosilicon composition according to claim 1, characterized in that, Component (B) is an organic compound represented by the following general formula (3). [Chemical Formula 3] In the formula, R 4 Z represents a hydrogen atom or a methyl group. 3 A divalent organic group consisting of 1 to 10 carbon atoms, either substituted or unsubstituted.

3. The photocurable organosilicon composition according to claim 1, characterized in that, The component (D) is silica powder that has been surface-treated with an organosilicon compound having (meth)acryloyl groups.

4. A liquid gasket, characterized in that, It is composed of the photocurable organosilicon composition according to any one of claims 1 to 3.

5. The cured product of the photocurable silicone composition according to any one of claims 1 to 3, characterized in that, The compression set measured after 100 hours of compression at 25% at 120°C was less than 30%.

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