UV curable silicone composition

Abstract

This invention provides a UV-curable polysiloxane composition with excellent curability and storage stability. The UV-curable polysiloxane composition of the present invention comprises: (A) a polyorganosiloxane having at least one alkenyl group in one molecule and an average alkenyl content of less than 0.3 mmol / g; (B) a polyorganohydrosiloxane having at least three hydrogen atoms bonded to silicon atoms in one molecule; and (C) a platinum-based catalyst activated by ultraviolet light.

Description

UV-curable polysiloxane composition This invention relates to ultraviolet-curable polysiloxane compositions, and more particularly to ultraviolet-curable polysiloxane compositions whose cured forms are suitable for use in sealing materials such as electronic component sealants, optical component sealants, and adhesives. Polysiloxane (PVC) compositions are used as elastic adhesives, sealants, coatings, and electrical insulating sealants in semiconductor components such as ICs and LSIs, electrical and electronic components that mount these semiconductor components, capacitors, resistors, etc., and optical components such as lenses, mirrors, filters, and prisms. This is because of their excellent heat resistance and the good adhesion and bonding properties they provide to these components. In particular, hydrosilicified UV-curable addition-reaction PVC compositions can be cured by short-term UV irradiation, resulting in excellent manufacturability and good bonding between components, hence their widespread use. As a UV-curable polysiloxane composition, Patent Document 1 discloses a UV-curable organopolysiloxane gel composition for damping materials of objective lens drive devices, which contains in a specific proportion: (A) an organopolysiloxane having an average of 0.1 or more alkenyl groups bonded to silicon atoms in one molecule; (B) an organohydrogen polysiloxane having 2 or more hydrogen atoms bonded to silicon atoms in one molecule; and (C) a photoactive platinum complex curing catalyst, which can serve as a composition that combines the advantages of designing specific polymers with rapid curing under UV irradiation. Furthermore, Patent Document 2 discloses an ultraviolet-curable liquid polysiloxane composition for an image display device, which contains, in a specific proportion: (A) an organopolysiloxane with a viscosity of 50 to 100,000 mPa·s at 25°C and having at least two alkenyl groups in one molecule; (B) a linear organohydrogen polysiloxane, such as an organohydrogen polysiloxane, having hydrogen atoms (Si-H groups) directly bonded to silicon atoms only at both ends of the molecular chain; and (C) one or more photoactive hydrosilylation reaction catalysts selected from a specific group of compounds, and having a specific viscosity. This ultraviolet-curable liquid polysiloxane composition can be cured in a few minutes to tens of minutes under mild temperature conditions below 100°C, and can form a cured product with good mechanical and optical properties. [Previous Technical Documents] [Patent Literature] Patent document 1: Japanese Patent Application Publication No. 2003-213132. Patent Document 2: Japanese Patent Application Publication No. 2019-210351. The ultraviolet-curable polysiloxane compositions disclosed in Patent Documents 1 and 2 are cured by irradiation with ultraviolet light. Although they exhibit specific mechanical and optical properties, the composition has poor storage stability. Over time, the viscosity of the composition increases, or the curing properties of the composition change, resulting in unstable quality of the cured product. To address the issue of storage stability, an attempt was made to formulate a two-component composition. However, at this time, the composition containing a photoactive curing catalyst in the first component of the two-component composition showed changes in viscosity and curing properties over time, thus requiring a two-component UV-curable polysiloxane composition to improve storage stability. The purpose of this invention is to provide UV-curable polysiloxane compositions with excellent curability and storage stability. In order to solve the above-mentioned problems, the inventors focused on alkenyl-containing polyorganosiloxanes and polyorganohydrosiloxanes that constitute UV-curable polysiloxane compositions, and through continuous in-depth research, they discovered that by controlling the alkenyl content in the polyorganosiloxane within a specific range and using a specific polyorganohydrosiloxane, the storage stability of the composition can be improved without compromising curability, thereby completing the present invention. This invention relates to the following [1] to [9]. [1] An ultraviolet-curable polysiloxane composition comprising: (A) a polyorganosiloxane having at least one alkenyl group in one molecule and having an average alkenyl content of less than 0.3 mmol / g; (B) a polyorganohydrosiloxane having at least three hydrogen atoms bonded to silicon atoms in one molecule; and (C) a platinum-based catalyst activated by ultraviolet light. [2] The UV-curable polysiloxane composition as described in [1], wherein the alkenyl group in component (A) is vinyl and the vinyl content is on average 0.001 to 0.3 mmol / g. [3] The UV-curable polysiloxane composition as described in [1] or [2], wherein the content of hydrogen atoms bonded to silicon atoms in component (B) is on average 5.5 mmol / g or more. [4] An ultraviolet-curable polysiloxane composition as described in any one of [1] to [3], wherein component (B) comprises a polyorganohydrosiloxane containing (B1)R c1 2HSiO 1 / 2 Unit (where R) c1 Independent as C 1-C 6-alkyl or C 6-C 20 Aryl) and SiO 4 / 2 unit. [5] The UV-curable polysiloxane composition as described in [4], wherein (B1) component is composed of 3 to 6 SiO bonds. 4 / 2 Units and 6 to 12 R c1 2HSiO 1 / 2 The unit is a polyorganohydrosiloxane. [6] The UV-curable polysiloxane composition as described in any one of [1] to [5], wherein component (C) is a platinum-based catalyst having a cyclic diene compound in the ligand group. [7] The UV-curable polysiloxane composition described in any one of [1] to [6] is composed of a first agent and a second agent, wherein the first agent contains component (A) and component (C) but does not contain component (B); and the second agent contains component (B) but does not contain component (C). [8] A sealing material is a cured material containing an ultraviolet-curable polysiloxane composition as described in any one of [1] to [7]. [9] The sealing material described in [8] is an electronic component sealing material, an optical component sealing material, or an adhesive material. The present invention provides UV-curable polysiloxane compositions with excellent curability and storage stability. The UV-curable polysiloxane composition contains: (A) a polyorganosiloxane having at least one alkenyl group per molecule with an average alkenyl content of 0.3 mmol / g or less; (B) a polyorganohydrosiloxane having at least three hydrogen atoms bonded to silicon atoms per molecule; and (C) a platinum-based catalyst activated by ultraviolet light. By ensuring that the average alkenyl content of component (A) is 0.3 mmol / g or less, and by using a polyorganohydrosiloxane having at least three hydrogen atoms bonded to silicon atoms per molecule (B), a UV-curable polysiloxane composition with excellent curing properties and storage stability can be formed. In this specification, "organic group" refers to a group containing carbon. The valence of an organic group is represented by "n-valence" as an arbitrary natural number, where n is used as an arbitrary natural number. Therefore, for example, a "monovalent organic group" refers to a group that has only one bond and contains carbon. The bond may contain elements other than carbon. Unless otherwise specified, those skilled in the art can determine the appropriate valence from the context. In this specification, "hydrocarbon group" refers to a group containing carbon and hydrogen and having at least one hydrogen atom removed from the molecule. There is no particular limitation on the hydrocarbon group; it can be substituted by one or more substituents. Examples of hydrocarbon groups with 1 to 20 carbon atoms include aliphatic hydrocarbon groups and aromatic hydrocarbon groups. The aforementioned "aliphatic hydrocarbon group" can be linear, branched, or cyclic, and can be saturated or unsaturated. Furthermore, the hydrocarbon group can contain one or more ring structures. Additionally, the hydrocarbon group can have one or more nitrogen (N), oxygen (O), sulfur (S), silicon (Si), amide bonds, sulfonamide bonds, siloxane bonds, carbonyl groups, carbonyl groups, carbonyloxy groups, or other heteroatoms or structures containing heteroatoms at its terminal or in the molecular chain. When used in this specification, the substituents of "hydrocarbon group" are not particularly limited, and examples include: halogen atoms; C atoms selected that can be substituted by one or more halogen atoms. 1- 6-alkyl, C 2-6 alkenyl, C 2-6 alkynyl group, C 3-10 cycloalkyl, C 3-10 Unsaturated cycloalkyl groups, 5 to 10 heterocyclic groups, 5 to 10 unsaturated heterocyclic groups, C 6-10 Aromatic and 5 to 10 heteroaryl groups. In this specification, unless otherwise specified, alkyl and phenyl groups may be unsubstituted or substituted. The substituents of this group are not particularly limited and may be selected from, for example, halogen atoms, C atoms, etc. 1- 6-alkyl, C 2-6 alkenyl and C 2-6 One or more alkynyl groups. In this specification, the structural units of siloxane compounds are referred to by the following abbreviations. These structural units are sometimes referred to as "M units", "D units", etc. M:(CH 3) 3SiO 1 / 2 . M H :H(CH) 3) 2SiO 1 / 2 . M Vi CH 2=CH(CH 3) 2SiO 1 / 2 . D: (CH) 3) 2SiO 2 / 2 . D H :H(CH) 3) SiO 2 / 2 . D Vi CH 2=CH(CH 3) SiO 2 / 2 . T: CH 3SiO 3 / 2 . Q: SiO 4 / 2 (Four senses) Silicon oxide compounds are constructed by combining the above-described structural units, but at least some of the methyl groups containing these structural units may be replaced with other groups such as halogenated fluorine groups or alkyl groups such as phenyl groups. For example, they may be described as D... H 20 D 20 The time does not refer to connecting 20 Ds H The unit is followed by 20 D units, which should be cleaved so that the units can be arranged arbitrarily. Silicon alkane compounds can form various three-dimensional structures through T units or Q units. <(A) Polyorganosiloxanes having at least one alkenyl group in one molecule and an average alkenyl content of less than 0.3 mmol / g> (A) is a polyorganosiloxane having at least one alkenyl group per molecule and an average alkenyl content of less than 0.3 mmol / g. (A) functions as a base polymer for UV-curable polysiloxane compositions. The alkenyl group can be bonded to the end of the molecular backbone, to a side chain in the middle of the molecular chain, or to both. In this specification, the molecular backbone refers to the longest bonded chain in the molecule. (A) has no particular limitation on its molecular structure as long as it is based on siloxane bonds; it can be linear, branched, cyclic, or three-dimensional network, or the siloxane backbone can be interrupted by divalent organic groups. (A) can be used alone or in combination of two or more. (A) Component A has at least one alkenyl group per molecule. Component A may be a mixture of several polyorganosiloxanes having at least one alkenyl group per molecule. For example, component A may be a mixture of a polyorganosiloxane having one alkenyl group per molecule and a polyorganosiloxane having two or more alkenyl groups per molecule. From the viewpoint of improving curability and imparting appropriate hardness to the cured material, it is preferable that component A contains at least 30% by mass of a polyorganosiloxane having two or more alkenyl groups per molecule, more preferably at least 50% by mass, and even more preferably at least 80% by mass, relative to 100% by mass of component A. The maximum content of polyorganosiloxanes having two or more alkenyl groups per molecule relative to 100% by mass is 100% by mass. From the perspective of balancing hardening properties and storage stability, and imparting appropriate hardness to the hardened material, component (A) preferably contains a polyorganosiloxane having two alkenyl groups per molecule, and more preferably a linear polyorganosiloxane having one alkenyl group at each end of the molecular backbone. In this case, component (A) preferably contains at least 30% by mass of a polyorganosiloxane having two alkenyl groups per molecule, more preferably at least 50% by mass, and even more preferably at least 80% by mass, relative to 100% by mass of component (A). The maximum content of the polyorganosiloxane having two alkenyl groups per molecule relative to 100% by mass of component (A) is 100% by mass. The alkenyl content of component (A) is on average 0.3 mmol / g or less. By keeping the alkenyl content within the above range, a UV-curable polysiloxane composition with excellent curing properties and storage stability can be formed. Here, when component (A) is a mixture of multiple polyorganosiloxanes having at least one alkenyl group in one molecule, the alkenyl content of component (A) is the average value of the mixture. (A) The alkenyl content of the component is determined by... 1 H NMR determination by CH 2=CH- group and CH 3-Based peak area to calculate CH 2=CH- group and CH The 3- molar ratio, and the molecular weight of component (A) determined from that molar ratio and CH 2 = CH - the value calculated using the mole number of the base. Also, except... 1 In addition to H NMR measurements, it can be used by 29 Si NMR measurements were used to calculate the values ​​of each unit (M). Vi The result of the ratio of (unit, D unit, etc.). When component (A) is a mixture of multiple polyorganosiloxanes, it is preferable to determine the alkenyl content of component (A) in the manner described above. However, if the alkenyl content of each polyorganosiloxane and its mixing ratio are known, the values ​​obtained by multiplying the individual alkenyl content by its mixing ratio can be summed, and the calculated average value can be used as the alkenyl content of the aforementioned component (A). From the perspective of balancing hardening properties and storage stability, the average alkenyl content of component (A) is preferably 0.001 to 0.3 mmol / g, more preferably 0.003 to 0.24 mmol / g, even more preferably 0.010 to 0.20 mmol / g, and even more preferably 0.025 to 0.10 mmol / g. There are no particular restrictions on the alkenyl group as long as it has a carbon-carbon double bond and can undergo addition reactions. The alkenyl group preferably has 2 to 20 carbon atoms, more preferably 2 to 8, and even more preferably 2 to 6. The alkenyl group can have a branched structure or a cyclic structure. The carbon-carbon double bond in the hydrocarbon constituting the alkenyl group can be in any position. From a reactivity point of view, the carbon-carbon double bond is preferably located at the end of the group. A preferred example of an alkenyl group for the easy synthesis of polyorganosiloxanes is a vinyl group. That is, it is preferred that the alkenyl group in component (A) is a vinyl group and that the vinyl content averages 0.001 to 0.3 mmol / g. In one embodiment of the present invention, component (A) has at least one alkenyl group bonded to a silicon atom in one molecule. Component (A) forms a network structure by an addition reaction with the hydrogen silicon group (Si-H group) of component (B) described later. A representative example of component (A) is a siloxane unit containing an alkenyl group as shown in general formula (1) in one molecule. R 1 m R 2 n SiO (4-m-n) / 2 (1) (in the formula, R 1 It is a non-substituted or substituted monovalent hydrocarbon group that does not have an aliphatic unsaturated bond; R 2 It is an alkenyl group; m is an integer from 0 to 2; n is an integer from 1 to 3, but m+n is from 1 to 3. R 1 R is a non-substituted or substituted monovalent hydrocarbon group that does not have an aliphatic unsaturated bond. 1 Specifically, examples include: alkyl groups, such as C14. 1-C 6-alkyl groups (e.g., methyl, ethyl, propyl, etc.); cycloalkyl groups, such as C64... 3 to C 10 Cycloalkyl (e.g., cyclohexyl); aryl, e.g., C 6 to C 20 Aryl (e.g., phenyl, tolyl, styryl, naphthyl, anthyl, etc.); aralkyl, e.g., C 7 to C 13 Aryl groups (e.g., 2-phenylethyl, 2-phenylpropyl, etc.); substituted hydrocarbon groups, such as halogenated hydrocarbon groups (e.g., chloromethyl, chlorophenyl, 3,3,3-trifluoropropyl, etc.). From the viewpoint of ease of synthesis, alkyl groups are preferred, among which methyl, ethyl, and propyl are more preferred, and methyl is even more preferred. Aryl groups can be used together to adjust the refractive index, among which phenyl is preferred from the viewpoint of ease of synthesis. From the viewpoint of obtaining a UV-curable polysiloxane composition with excellent curing properties and storage stability, component (A) is preferably a linear polyorganosiloxane containing one alkenyl group at each end of the molecular backbone. In one embodiment of the present invention, the linear polyorganosiloxane may be represented, for example, by formula (I). (in the formula, R a1 Independently for C 2-C 6-Alkenyl R b1 Independently for C 1-C 6-alkyl or C 6-C 20 Aryl, n1 is the number of linear polyorganosiloxanes with an average alkenyl content of less than 0.3 mmol / g. C 2-C Examples of 6-alkenyl groups include vinyl, allyl, 3-butenyl, and 5-hexenyl. 1-C Examples of 6-alkyl groups include methyl, ethyl, propyl, butyl, pentyl, and hexyl. C 6-C 20 Examples of aryl groups include phenyl, naphthyl, and allyl. From the perspective of ease of synthesis without compromising the flowability of the uncured components and the heat resistance of the cured product, R a1 Vinyl is preferred. Considering its ease of synthesis and excellent balance between the flowability of its components and the mechanical strength of the cured product, R... b1 C is preferred 1-C 6-alkyl, preferably methyl. Therefore, component (A) is preferably a polymethylvinylsiloxane with dimethylvinylsiloxane units at both ends and a dimethylsiloxane unit in the middle. (A) Of 100% by mass, the content of polymethylvinylsiloxane, which is composed of dimethylvinylsiloxane units at both ends and dimethylsiloxane units in the middle, is preferably 30% by mass or more, more preferably 50% by mass or more, and even more preferably 80% by mass or more. The aforementioned content limit is 100% by mass. (A) The component may be a polymethyl vinyl silicate with dimethyl vinyl silicate units at both ends and dimethyl silicate units in the middle, or a mixture of other linear, branched or cyclic polyorganosiloxanes containing alkenyl groups. In a preferred embodiment of the present invention, the alkenyl group in component (A) is vinyl and the vinyl content is 0.001 to 0.3 mmol / g. From the viewpoint of balancing curability and storage stability, the average vinyl content of component (A) is preferably 0.001 to 0.3 mmol / g, more preferably 0.003 to 0.24 mmol / g, even more preferably 0.010 to 0.20 mmol / g, and even more preferably 0.025 to 0.10 mmol / g. (A) Components can be commercially available products. Alternatively, polyorganosiloxanes with alkenyl groups introduced via known reactions can be used. Depending on the position or type of substituents, degree of polymerization, etc., component (A) can use only one type of compound, or a mixture of two or more types of compounds. Since component (A) is a polyorganosiloxane, it can be a mixture of polyorganosiloxanes with various degrees of polymerization. From the perspective of balancing processability, curability and storage stability, the amount of component (A) is preferably 70.0 to 99.8% by mass, more preferably 80.0 to 99.7% by mass, and even more preferably 90.0 to 99.7% by mass, relative to 100% by mass of UV-curable polysiloxane composition. <(B) Polyorganohydrosiloxanes with at least 3 hydrogen atoms bonded to silicon atoms in one molecule> Component (B) is a polyorganohydrosiloxane having at least three hydrogen atoms bonded to silicon atoms in one molecule. Component (B) functions as a crosslinking agent and forms a network structure through an addition reaction with the alkenyl groups of component (A). Compared to polyorganohydrosiloxanes having two hydrogen atoms bonded to silicon atoms in one molecule, component (B) exhibits superior curability and can form a network structure with component (A). Therefore, even when using polyorganosiloxanes with lower alkenyl content, such as component (A), it is possible to maintain storage stability and form a composition with excellent curability and mechanical properties of the cured product. (B) The hydrogen atoms of component (B) may be bonded to silicon atoms at the ends of the molecular chain, or to silicon atoms in the middle of the molecular chain, or to both. There are no particular restrictions on the molecular structure of component (B), as long as it is based on a siloxane bond as the main framework; it can be linear, branched, cyclic, or a three-dimensional network, or the siloxane framework may be interrupted by a divalent organic group. Furthermore, component (B) may have hydroxyl groups or alkoxy groups such as methoxy and ethoxy bonded to silicon atoms. Component (B) may be used alone or in combination with two or more of the following. (B) A representative example of a component is a siloxane unit containing at least three hydrogen atoms bonded to silicon atoms, as shown in general formula (2). R 3 pH q SiO (4-p-q) / 2 (2) (in the formula, R 3 It is a non-substituted or substituted monovalent hydrocarbon group that does not have an aliphatic unsaturated bond; p is an integer from 0 to 2; q is an integer from 1 to 3, but p+q is from 1 to 3. R 3 Examples of R in general formula (1) can be cited. 1 The same applies to the preferred state. In component (B), the number of hydrogen atoms bonded to silicon atoms in one molecule is preferably 3 to 100, more preferably 5 to 50. From the perspective of the curability of the composition and the mechanical properties of the cured product, the average content of hydrogen atoms bonded to silicon atoms in component (B) is preferably 5.5 mmol / g or more, more preferably 6.0 to 12.0 mmol / g, even more preferably 7.0 to 11.0 mmol / g, and particularly preferably 8.0 to 11.0 mmol / g. From the perspective of ensuring hardening properties and the mechanical properties of the hardened product, component (B) is preferably one containing (B1)R. c1 2HSiO 1 / 2 Unit (where R) c1 Independently for C 1-C 6-alkyl or C 6-C 20 Aryl) and SiO 4 / 2 The unit is a polyorganohydrosiloxane. Component (B) contains component (B1), which helps to create a network structure in the hardened material and adjust its hardness. Component (B1) can be a branched, cyclic, or three-dimensional network structure (composed of SiO2). 4 / 2 Any of the densely packed unit structures. From the perspective of ease of synthesis, R c1 C is preferred 1-C 6-alkyl, preferably methyl. Among them, (B1) composition is preferred as it has 3 to 6 SiO bonds. 4 / 2 Units and 6 to 12 R c1 2HSiO 1 / 2 The unit is a polyorganohydrosiloxane; preferably, it is such as [R] c1 2HSiO 1 / 2 ] 6[SiO 4 / 2 ] 3. [R] c1 2HSiO 1 / 2 ] 8[SiO 4 / 2 ] 4. [R] c1 2HSiO 1 / 2 ] 10 [SiO 4 / 2 ] 5. [R] c1 2HSiO 1 / 2 ] 12 [SiO 4 / 2 ] 6 generally consists of 3 to 6 SiO 4 / 2 The unit cell forms a cyclic siloxane framework, and in each SiO₂ cell... 4 / 2 Unit bond 2 R c1 2HSiO 1 / 2 The unit is a cyclic polyorganohydrosiloxane. From the viewpoint of ensuring hardening properties and the mechanical properties of the hardened product, the content of component (B1) is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more, relative to 100% by mass of component (B). The upper limit of the content of component (B1) is 100% by mass relative to 100% by mass of component (B). (B) The viscosity of component at 23°C is preferably 1 to 100 mPa·s, more preferably 1 to 50 mPa·s. The viscosity is measured according to JIS K 6249 using a rotational viscometer with rotor No. 1 or 2, 60 rpm, and 23°C. (B) Component can be a commercially available product. Alternatively, (B) Component can be synthesized using known reactions. Depending on the position or type of substituents, degree of polymerization, etc., (B) Component can use only one type of compound, or a mixture of two or more types of compounds. (B) Component is a polyorganohydrosiloxane, therefore it can be a mixture of polyorganohydrosiloxanes with various degrees of polymerization. From the perspective of balancing processability, hardening properties and storage stability, component (B) is preferably blended in such a way that the number of hydrogen atoms bonded to silicon atoms is in the range of 0.6 to 2.2 mol relative to component (A) with 1 mol of alkenyl group, more preferably in the range of 0.8 to 1.8 mol, even more preferably in the range of 1.0 to 1.6 mol, and most preferably in the range of 1.2 to 1.4 mol. <(C) Platinum-based catalysts activated by ultraviolet light> Component (C) is a catalyst activated by ultraviolet light to promote the addition reaction between the alkenyl group of component (A) and the silyl group (Si-H group) of component (B). From the viewpoint of good catalyst activity, component (C) is preferably a platinum-based catalyst with a cyclic diene compound in the ligand group. Component (C) can be used alone or in combination with two or more other components. Examples of platinum-based catalysts with cyclic diene compounds as ligands include (1,5-cyclooctadienyl)diphenylplatinum complexes, (1,5-cyclooctadienyl)dipropylplatinum complexes, (2,5-norcampadiene)dimethylplatinum complexes, (2,5-norcampadiene)diphenylplatinum complexes, (cyclopentadienyl)dimethylplatinum complexes, (methylcyclopentadienyl)diethylplatinum complexes, (trimethylsilylcyclopentadienyl)diphenylplatinum complexes, and (methylcyclooctyl-1,5-diene)diphenylplatinum complexes. (Cyclopentadienyl)trimethylplatinum wrought iron, (cyclopentadienyl)ethyldimethylplatinum wrought iron, (cyclopentadienyl)ethoxydimethylplatinum wrought iron, (methylcyclopentadienyl)trimethylplatinum wrought iron, (methylcyclopentadienyl)trihexylplatinum wrought iron, (trimethylsilylcyclopentadienyl)trimethylplatinum wrought iron, (dimethylphenylsilylcyclopentadienyl)triphenylplatinum wrought iron, (cyclopentadienyl)dimethyltrimethylsilylmethylplatinum wrought iron, etc. The dosage of component (C) is preferably 0.1 to 500 ppm by weight of platinum metal relative to the total mass of components (A) and (B), more preferably 1 to 100 ppm, even more preferably 3 to 70 ppm, and most preferably 5 to 20 ppm. If the dosage of component (C) is less than 0.1 ppm, the addition reaction under ultraviolet irradiation may be slowed down or fail to harden. If it exceeds 500 ppm, the ultraviolet-cured polysiloxane composition is prone to deterioration of storage stability and yellowing of the cured product, resulting in higher costs. <Other Ingredients> UV-curable polysiloxane compositions may be blended with other components without compromising their purpose or effect. These other components may include flame retardants, adhesion promoters, heat-resistant promoters, diluents, volatile modifiers such as fumed silica, inorganic or organic pigments, inhibitors of addition reaction curing catalysts, and resins other than polyorganosiloxanes. Furthermore, UV-curable polysiloxane compositions may be blended with: (A) polyorganosiloxanes other than the components, such as polyorganosiloxanes without alkenyl groups; (B) polyorganohydrosiloxanes other than the components, such as polyorganohydrosiloxanes having two or fewer hydrogen atoms bonded to silicon atoms in one molecule; and (C) addition reaction curing catalysts other than the components, such as addition reaction curing catalysts activated by heat. These other components may be used alone or in combinations of two or more. <Preferred composition> The UV-curable polysiloxane composition can be a single liquid composition containing all components (A) to (C), or a two-liquid composition in which components (B) and (C) are contained in other containers to further improve the storage stability of the composition. When forming a two-liquid composition, it is preferable that the first agent contains components (A) and (C) but not component (B), and the second agent contains component (B) but not component (C). In this case, the second agent may contain component (A). The two-liquid composition is prepared by mixing the first and second agents during use to produce an ultraviolet-curable polysiloxane composition. In the embodiments, to focus solely on the effect of the interaction between the alkenyl group of component (A) and component (C) on storage stability, for the two-liquid composition consisting of a first agent containing only components (A) and (C) and a second agent containing only component (B), only the first agent was subjected to a maturation treatment for evaluation. For the one-liquid composition containing components (A), (C), and (B), the storage stability of the composition was also improved by using component (A). <Method for manufacturing ultraviolet-curable polysiloxane compositions> A liquid-type UV-curable polysiloxane composition can be obtained by mixing components (A) to (C) and other components as needed using a mixer such as a planetary mixer. During mixing, heating can be performed simultaneously within a range of 50 to 150°C, as needed. When the UV-curable polysiloxane composition contains powder, it is preferable to perform the mixing operation under high shear force to ensure uniformity. Mixing equipment includes three-roll mills, colloid mills, sand mills, etc., with three-roll mills being the preferred method. The two liquid-type UV-curable polysiloxane composition is prepared by separately preparing the first agent and the second agent. The first agent can be obtained by mixing component (A), component (C), and other components as needed using a mixer such as a planetary mixer. The second agent can be obtained by mixing component (B), component (A), and other components as needed using a mixer such as a planetary mixer. During mixing, heating can be performed while mixing in the range of 50 to 150°C as needed. When the first agent and / or the second agent contains powder, it is preferable to perform the mixing operation in the same manner as the one-liquid UV-curable polysiloxane composition. From the viewpoint of spreadability during coating, the viscosity of the UV-curable polysiloxane composition at 23°C is preferably below 100,000 mPa·s, more preferably 50 to 50,000 mPa·s. When the UV-curable polysiloxane composition is a two-component composition consisting of a first agent and a second agent, the viscosity of the first agent and the second agent is preferably 10 to 100,000 mPa·s, more preferably 50 to 50,000 mPa·s, and particularly preferably 100 to 20,000 mPa·s. The UV-curable polysiloxane composition is preferably stored at a temperature below room temperature under light-shielding conditions. The viscosities of the UV-curable polysiloxane composition, the first agent, and the second agent are values ​​measured using a viscoelasticity measuring device and a 25 mm cone plate at a shear rate of 10 / s and at 23°C. <Curing Methods for UV-Curable Polysiloxane Compositions> UV-curable polysiloxane compositions can be cured by irradiation with ultraviolet light. The preferred irradiation dose is 100 to 10,000 mJ / cm². 2 The optimal value is 300 to 6,000 mJ / cm³. 2 Even better is 500 to 5,000 mJ / cm³. 2Furthermore, the irradiation dose is the measured value of UVA. Here, UVA refers to ultraviolet radiation in the range of 315 to 400 nm. The composition exhibits good curing properties when irradiated with ultraviolet light at wavelengths, such as 250 to 450 nm. Examples of ultraviolet light sources emitting this wavelength include high-pressure mercury lamps (UV-7000) and metal halide lamps (UVL-4001M3-N1) manufactured by USHIO Electric Co., Ltd., metal halide lamps (JM-MTL 2KW) manufactured by JMtech Co., Ltd. of South Korea, ultraviolet irradiation lamps (OSBL360) manufactured by Mitsubishi Electric Co., Ltd., ultraviolet irradiation machines (UD-20-2) manufactured by GS-YUASA Co., Ltd., fluorescent lamps (FL-20BLB) manufactured by Toshiba Co., Ltd., H valves, H+ valves, V valves, D valves, Q valves and M valves manufactured by Heraeus Co., Ltd., and LED lamps (HLDL-155UV) manufactured by CCS Co., Ltd. The curing time of the composition varies depending on the amount of ultraviolet irradiation, but is generally less than 30 minutes, preferably less than 10 minutes. Curing can be visually assessed, but it can also be quantitatively evaluated by the time until the storage elastic modulus G' equals the loss elastic modulus G', or the time until the storage elastic modulus G' reaches a specific value. For example, if the time for the storage elastic modulus G' to reach 100 Pa at 23°C after ultraviolet irradiation is less than 30 minutes (preferably less than 10 minutes), it can be considered to have a short curing time and excellent processability, and is therefore preferred. Cured UV-curable polysiloxane (UVC) compositions are suitable for use as sealants. Articles using UVC-curable polysiloxane compositions as sealants exhibit excellent water resistance and durability at the bonding surfaces and seals, making them suitable for use as sealants for electronic components, optical components, or as bonding agents. Furthermore, UVC-curable polysiloxane compositions offer excellent shelf life and storage stability. Therefore, they can be used, for example, as adhesives for bonding liquid crystal, plasma, and organic EL image display devices, or as sealants for sealing LED or OLED components. [Example] The invention is further described in detail below with examples and comparative examples. However, the invention is not limited to these examples. Unless otherwise specified, all terms are parts by mass or percentages by mass. <Ingredients> The ingredients used are as follows. The symbols are shown below. M:(CH 3) 3SiO 1 / 2 . M H :H(CH) 3) 2SiO 1 / 2 . M Vi CH 2=CH(CH 3) 2SiO 1 / 2 . D: (CH) 3) 2SiO 2 / 2 . D H :H(CH) 3) SiO 2 / 2 . D Vi CH 2=CH(CH 3) SiO 2 / 2 . Q: SiO 4 / 2 (Four senses) (A) Composition: Polyorganosiloxane having at least one alkenyl group per molecule and an average alkenyl content of less than 0.3 mmol / g. Use the two ends shown below with M Vi Polymethyl vinyl siloxane with unit barrier and intermediate unit composed of D unit. M Vi D m1 M Vi (1): The average vinyl content is 0.030 mmol / g. M Vi D m2 M Vi (2): The average vinyl content is 0.049 mmol / g. M Vi D m3 M Vi (3): The average vinyl content is 0.075 mmol / g. M Vi D m4 M Vi (4): The average vinyl content is 0.178 mmol / g. M Vi D m5 M Vi (5): The average vinyl content is 0.227 mmol / g. (A') Ingredients: Polyorganosiloxanes other than (A) M Vi D m6 M Vi (6): The average vinyl content is 0.341 mmol / g. M Vi D m7 M Vi (7): The average vinyl content is 0.887 mmol / g. M Vi D m3 M Vi (3) / MD Vi Q resin = 60 / 40: average vinyl content is 0.475 mmol / g (MD) Vi Q resin consists of 5 vinyl groups per molecule with a vinyl content of 1.075 mmol / g. Furthermore, the alkenyl content of components (A) and (A') is determined by... 1 Measured by H NMR from CH 2=CH- group and CH 3-Based peak area to calculate CH 2=CH- group and CH The 3- molar ratio, and the molecular weight of components (A) and (A') determined from the molar ratio and CH The molar number of the 2=CH- group was calculated separately. Specifically, a 5% by mass dichloroform solution of component (A) or (A') was prepared and subjected to... 1 ¹H NMR determination. The SiCH=CH content was observed around 6 ppm. Peak area of ​​2-base and SiCH content near 0 ppm CH is calculated from the peak area of ​​the three bases. 2=CH- group and CH The molar ratio of 3-yl groups, and the molecular weight of component (A) or (A') and CH from the molar ratio. 2=CH- molar number. The molecular weights of components (A) and (A') thus obtained and CH The alkenyl content of components (A) and (A') was calculated by the molar number of the 2=CH- group. (B) Composition: Polyorganohydrosiloxane with at least 3 hydrogen atoms bonded to silicon atoms in one molecule. Average unit formula such as M H 8Q The cross-linked polymethylhydrosiloxane shown in Figure 4 (SiH content: 10.78 mmol / g). (C) Ingredients: Platinum-based catalyst activated by ultraviolet light (Methylcyclopentadienyl)trimethylplatinum complex (Strem Chemicals, Inc., Germany, platinum content: 61.1% by mass). Example 1 To prevent ultraviolet light from activating the catalyst, the treatment of component (C) was carried out in a yellow light chamber. Component (C) was then treated with M... Vi D m2 M Vi (2) Dilute to 0.05% by mass. (at M) Vi D m1 M Vi (1) Add 3.4 parts by weight of the diluted solution of the aforementioned component (C) to 100 parts by weight (Component (C): 0.00170 parts by weight, M Vi D m2 M Vi(2): 3.39830 parts by mass of component (B) and 0.36 parts by mass of component (B) were mixed to obtain the liquid-type UV-curable polysiloxane composition of Example 1. Examples 2 to 6 and Comparative Examples 1 to 3 The components (A) to (C) in Example 1 and their doping amounts were changed as shown in Table 1. Otherwise, the liquid-type UV-curable polysiloxane compositions of Examples 2 to 6 and Comparative Examples 1 to 3 were obtained in the same manner as in Example 1. [Table 1] <Determination Method> Viscosity and gelation time were measured under light-shielding conditions. [Viscosity] The viscosity (Pa·s) of the UV-curable polysiloxane composition at 23°C was determined using a viscoelasticity measuring apparatus MCR301 (Anton Paar) with a 25 mm cone plate at a shear rate of 10 / s and a 90-second time. The results are shown in Table 2. [Gel time] For UV-curable polysiloxane compositions, the storage elastic modulus G' before and after UV irradiation was measured over time using a viscoelasticity measuring device MCR301 (manufactured by Anton Paar). The aforementioned viscoelasticity measuring device was used, and an 8mm parallel plate was used at a frequency... 1 The storage elastic modulus G' of the UV-curable polysiloxane composition at 23°C was determined starting at Hz. An illuminance of 100 mW / cm² was used. 2 UV-curable polysiloxane was irradiated with ultraviolet light for 10 seconds (irradiation dose 1,000 mJ / cm). 2 The gelation time was defined as the time from the start of irradiation until the storage elastic modulus G' reached 100 Pa. A shorter gelation time indicates faster curing and is considered superior curing properties. Furthermore, the gelation time was measured up to 60 minutes after the start of UV irradiation; if the storage elastic modulus G' had not reached 100 Pa at this point, the gelation time was considered to be >60 minutes. The results are shown in Table 2. [Maintain stability] In the UV-curable polysiloxane compositions of Examples 1 to 6 and Comparative Examples 1 to 3, the effect of aging treatment on the viscosity and gelation time of the compositions was analyzed. Example 1-1 To prevent ultraviolet light from activating the catalyst, the treatment of component (C) was carried out in a yellow light chamber. Component (C) was then treated with M... Vi D m2 M Vi (2) Dilute to 0.05% by mass. (at M) Vi D m1 M Vi (1) Add 3.4 parts by weight of the diluted solution of the aforementioned component (C) to 100 parts by weight (Component (C): 0.00170 parts by weight, M Vi D m2 M Vi (2): 3.39830 parts by weight) were mixed to obtain the first agent. The first agent was transferred to a light-shielding black resin container and sealed. Component (B) was used directly as the second agent. In the above manner, the liquid-type UV-curable polysiloxane composition of Example 1-1, which is the same as that of Example 1, can be obtained. Examples 2-1 to 6-1 and Comparative Examples 1-1 to 3-1 The components (A) to (C) and their doping amounts in Examples 1-1 were changed as shown in Table 1. Otherwise, the liquid-type UV-curable polysiloxane compositions of Examples 2-1 to 6-1 and Comparative Examples 1-1 to 3-1 were obtained in the same manner as in Examples 1-1. In the two-liquid UV-curable polysiloxane compositions of Examples 1-1 to 6-1 and Comparative Examples 1-1 to 3-1, each light-shielding container containing the first agent was stored in a dryer set at 60°C for 2 weeks for curing. The second agent was added to the first agent after curing, as shown in Table 1, and mixed to obtain the UV-curable polysiloxane composition. The viscosity and gelation time of the resulting compositions were measured. The results are shown in Table 2. Furthermore, the rate of change of viscosity of the composition prepared after the first agent's aging treatment relative to the viscosity of the liquid composition was calculated, as well as the change of gelation time of the composition prepared after the first agent's aging treatment relative to the gelation time of the liquid composition. The results are shown in Table 2. In the table, nd indicates that it cannot be determined. [Table 2] As shown in Table 2, the UV-curable polysiloxane compositions of the examples contain: (A) a polyorganosiloxane having at least one alkenyl group per molecule with an average alkenyl content of 0.3 mmol / g or less; (B) a polyorganohydrosiloxane having at least three hydrogen atoms bonded to silicon atoms per molecule; and (C) a platinum-based catalyst activated by ultraviolet light. These UV-curable polysiloxane compositions exhibit shorter gelation times, excellent curing properties, and less variation in viscosity and gelation time after the first agent is cured, resulting in superior storage stability. In particular, Examples 1 to 3 and 1-1 to 3-1, where the average alkenyl content of component (A) is 0.025 to 0.10 mmol / g, show less variation in gelation time after the first agent is cured, and exhibit shorter gelation times and excellent curing properties regardless of whether curing treatment is performed, thus making them superior. Comparative Examples 1 to 3 and 1-1 to 3-1, which replace component (A) with a polyorganosiloxane having at least one alkenyl group in one molecule and an average alkenyl content of more than 0.3 mmol / g, exhibited greater changes in viscosity and gelation time after the first agent was cured, resulting in poorer storage stability. Furthermore, regardless of whether a curing treatment was performed, the gelation time was longer and the curability was poorer. [Industrial Utilization] Cured UV-curable polysiloxane compositions can be used as sealants for electronic components, optical components, or as bonding materials.

Claims

1. An ultraviolet-curable polysiloxane composition comprising: (A) a polyorganosiloxane having at least one alkenyl group in one molecule and having an average alkenyl content of less than 0.3 mmol / g; (B) a polyorganohydrosiloxane having at least three hydrogen atoms bonded to silicon atoms in one molecule; and (C) a platinum-based catalyst activated by ultraviolet light, wherein component (B) comprises a polyorganohydrosiloxane containing (B1)Rc12HSiO1 / 2 units and SiO4 / 2 units, wherein in formula (B1), Rc1 is independently a C1-C6 alkyl or a C6-C20 aryl group.

2. The UV-curable polysiloxane composition as described in claim 1, wherein, (A) The alkenyl group in the component is vinyl and the vinyl content is on average 0.001 to 0.3 mmol / g.

3. The UV-curable polysiloxane composition as described in claim 1 or 2, wherein, (B) The average content of hydrogen atoms bonded to silicon atoms in the component is above 5.5 mmol / g.

4. The UV-curable polysiloxane composition as described in claim 1 or 2, wherein, (B1) is a polyorganohydrosiloxane with 3 to 6 SiO4 / 2 units and 6 to 12 Rc12HSiO1 / 2 units bonded together.

5. The UV-curable polysiloxane composition as described in claim 1 or 2, wherein, (C) is a platinum-based catalyst with a cyclic diene compound in the ligand.

6. The UV-curable polysiloxane composition as described in claim 1 or 2 is composed of a first agent and a second agent, wherein the first agent contains components (A) and (C) but does not contain component (B); and the second agent contains component (B) but does not contain component (C).

7. A sealing material comprising a cured material containing an ultraviolet-curable polysiloxane composition as described in claim 1 or 2.

8. The sealing material described in claim 7 is an electronic component sealing material, an optical component sealing material, or an adhesive material.