Method for producing a curable liquid silicone composition and method for curing said composition

Abstract

Provided is a curable liquid silicone composition comprising two types of platinum catalysts which are a platinum catalyst that is activated by irradiation with UV rays to act as a hydrosilylation addition reaction catalyst and an aerobic platinum catalyst mixture that is activated by being in contact with moisture and / or oxygen, particularly with atmospheric moisture (humidity) and / or oxygen to act as hydrosilylation addition reaction catalyst. The curable liquid silicone composition has long-term storage stability as a single-liquid composition. Said composition is a curable liquid silicone rubber composition or a curable liquid silicone gel composition that, after being irradiated with UV rays at room temperature and further being exposed to the atmosphere for a prescribed time, exhibits excellent UV curing properties and favorable curing properties of a non-UV-irradiated part (shadow parts).

Description

[Technical Field]

[0001] The present invention relates to a curable liquid silicone composition (curable liquid silicone rubber composition or curable liquid silicone gel composition) that contains two platinum catalysts: a platinum catalyst that is activated by ultraviolet light, and a platinum catalyst mixture that is activated by moisture and / or oxygen, and that can be cured to give a cured silicone rubber (a silicone elastomer elastic body) or a cured silicone gel. Manufacturing method The present invention also relates to a method for curing the curable liquid silicone composition. [Background technology]

[0002] In light of the demands for energy conservation and the SDGs (Sustainable Development Goals), there has been a growing demand in recent years for curable liquid silicone compositions that can be cured without heating. Furthermore, in order to simplify the use of curable liquid silicone compositions and to prevent errors during use, one-component curable liquid silicone compositions are preferred.

[0003] Among the curable liquid silicone compositions that are one-component and can be cured without heating through crosslinking reactions such as condensation reactions, UV radical reactions, and hydrosilylation addition reactions, some have extremely short shelf lives, and some can activate the catalyst with UV light. However, all of these reactions have insufficient deep curing ability or curing ability in the shadow areas of UV light, limiting the applications in which they can be used.

[0004] The following are examples of prior art related to the present invention. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. 4,510,094 [Patent Document 2] U.S. Patent No. 4,530,879 [Patent Document 3] Patent No. 6020740 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in view of the above circumstances, and provides a curable liquid silicone composition which can be stored in a single liquid form for an extended period of time in a light-shielded sealed container under refrigeration or room temperature (-5 to 38°C), and which, when irradiated with ultraviolet light without heating (i.e., at room temperature (23°C±15°C)) and brought into contact with moisture and / or oxygen, particularly moisture (humidity) and / or oxygen in the atmosphere, cures in the ultraviolet irradiated areas and also cures in the non-irradiated areas (shadow areas) and shadow areas that are not reached by ultraviolet light, to give a cured silicone rubber or cured silicone gel product. Manufacturing method and a method for curing the curable liquid silicone composition. [Means for solving the problem]

[0007] The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result have discovered that a curable liquid silicone composition containing two platinum catalysts - a platinum catalyst that is activated by irradiation with ultraviolet light and acts as a hydrosilylation addition reaction catalyst, and an aerobic platinum catalyst mixture that is activated by contact with moisture and / or oxygen, particularly atmospheric moisture (humidity) and / or oxygen, and acts as a hydrosilylation addition reaction catalyst - has long-term storage stability as a one-component composition, and that when this composition is irradiated with ultraviolet light at room temperature and then exposed to the atmosphere for a predetermined period of time, it becomes a curable liquid silicone rubber composition or curable liquid silicone gel composition that exhibits excellent UV curability and good curability in areas not irradiated with UV light (shadow areas), thereby completing the present invention.

[0008] The present invention cures a liquid silicone composition into silicone rubber or silicone gel using a curing (crosslinking) reaction system that employs a hydrosilylation addition reaction using a platinum-based catalyst that is activated by ultraviolet light and a mixture of (aerobic) platinum-based catalysts that are activated by moisture and / or oxygen. However, what is particularly noteworthy is that the curable liquid silicone composition of the present invention can be stored as a single-part product in a sealed container protected from light at temperatures ranging from refrigeration to room temperature (-5 to 38°C), and that when exposed to ultraviolet light and in the absence of heat (i.e., room temperature (23°C±15°C)), the catalytic function is activated by exposure to ultraviolet light and contact with air (atmospheric moisture (humidity) and / or oxygen), causing the hydrosilylation addition reaction to proceed, resulting in curing not only in the UV-irradiated areas but also in the shaded areas.

[0009] Therefore, the present invention provides the following curable liquid silicone composition: Manufacturing method and a method for curing the curable liquid silicone composition. [1] (A) a diorganopolysiloxane having at least one alkenyl group per molecule; (B) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms per molecule: an amount such that there are 0.5 to 4 moles of silicon-bonded hydrogen atoms in component (B) per mole of alkenyl groups in component (A); (C) an ultraviolet-activated platinum-based catalyst: an amount such that the mass of platinum atoms in component (C) is 0.1 to 1,000 ppm relative to the total mass of component (A) and component (B); (D )water A platinum-based catalyst mixture activated by oxygen and / or water: an amount equivalent to 0.1 to 1,000 ppm by mass of platinum atoms in component (D) relative to the total mass of components (A) and (B). A curable liquid silicone composition comprising In the manufacturing method of A method for producing a curable liquid silicone composition, comprising the steps of: mixing, as component (D), a platinum-alkenyl group-containing organosiloxane complex with an organohydrogensiloxane oligomer having, per molecule, at least two hydrogen atoms (adjacent SiH groups) bonded to adjacent silicon atoms via ether oxygen atoms that form siloxane bonds (Si-O-Si), in an amount such that the number of hydrogen atoms bonded to silicon atoms is in molar excess relative to the alkenyl groups in the platinum-alkenyl group-containing organosiloxane complex; and contacting the resulting mixture with water and / or oxygen to obtain a reaction mixture. . [2] The curable liquid silicone composition one-component Things The curable liquid silicone composition according to [1], Manufacturing method . [3] The curable liquid silicone composition according to [1] or [2], wherein the organohydrogensiloxane oligomer is 1,1,3,3-tetramethyldisiloxane, 1,1,1,3,5,7,7,7-octamethyltetrasiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, or 1,3,5,7,9-pentamethylcyclopentasiloxane. Manufacturing method . [4] The curable liquid silicone composition The curable liquid silicone composition according to any one of [1] to [3], further comprising (E) a dehydrating agent in an amount of 0.01 to 5% by mass of the total composition. Manufacturing method . [5] The curable liquid silicone composition The curable liquid silicone composition according to any one of [1] to [4], further comprising (F) a hydrosilylation addition reaction inhibitor in an amount of 0.1 to 1 mole per mole of platinum atoms contained in the composition. Manufacturing method . [6] The curable liquid silicone composition according to any one of [1] to [5]. Curable liquid silicone composition produced by the method of and then exposing the composition to the atmosphere for a predetermined period of time. [Effects of the Invention]

[0010] The curable liquid silicone composition of the present invention is one in which the curing reaction proceeds through the use of two platinum catalysts: a platinum catalyst that is activated by ultraviolet irradiation to act as a hydrosilylation addition reaction catalyst, and an aerobic platinum catalyst mixture that is activated by contact with moisture and / or oxygen, particularly atmospheric moisture (humidity) and / or oxygen, to act as a hydrosilylation addition reaction catalyst. The curable liquid silicone composition of the present invention, which contains the platinum catalyst and platinum catalyst mixture, has a sufficiently long shelf life as a one-part product when stored and transported at refrigerated to room temperature in a light-shielded sealed container. When in use, the platinum catalyst and platinum catalyst mixture contained in the composition are activated by ultraviolet irradiation and contact with moisture and / or oxygen, particularly atmospheric moisture (humidity) and / or oxygen, under unheated conditions (i.e., at room temperature), causing the hydrosilylation addition reaction to proceed, enabling rapid curing not only on the UV-irradiated surface but also in shadowed areas. Therefore, the curable liquid silicone compositions of the present invention (curable liquid silicone rubber compositions and curable liquid silicone gel compositions) can contribute to energy conservation and the production of various parts and products in line with the SDGs. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described in detail below.

[0012] [Curable liquid silicone composition] The curable liquid silicone composition of the present invention (curable liquid silicone rubber composition or curable liquid silicone gel composition) is a composition containing the components (A) to (D) described below, and, if necessary, other components.

[0013] [(A) Alkenyl group-containing diorganopolysiloxane] The alkenyl-containing diorganopolysiloxane of component (A) is a linear or branched diorganopolysiloxane having at least one, and preferably 1 to 20, alkenyl groups per molecule. It functions as the main component (base polymer) of the curable liquid silicone composition of the present invention (hereinafter also referred to as the composition of the present invention). Typically, it is a linear diorganopolysiloxane whose main chain is essentially composed of repeating diorganosiloxane units and whose molecular chain is terminated at both ends with triorganosiloxy groups; however, it may also be a branched diorganopolysiloxane containing a branched structure as part of the siloxane structure that makes up the molecular chain.

[0014] The alkenyl-containing diorganopolysiloxane of component (A) contains at least one alkenyl group (usually 1 to 50), preferably 1 to 20, more preferably 2 to 10, and even more preferably 2 alkenyl groups per molecule. Examples of alkenyl groups include vinyl, allyl, propenyl, isopropenyl, butenyl, hexenyl, and cyclohexenyl, which typically have about 2 to 8 carbon atoms. The alkenyl group may be bonded to a silicon atom at a molecular chain terminal or a non-terminal (mid-chain) silicon atom. Preferably, the alkenyl group contains alkenyl groups bonded to silicon atoms at at least one or both terminals of the molecular chain. In this case, the alkenyl groups may be present only at one or both terminals of the molecular chain, or at one or both terminals and non-terminals (mid-chain) of the molecular chain.

[0015] Such alkenyl group-containing diorganopolysiloxanes include, for example, linear diorganopolysiloxanes represented by the following general formula (1). [ka] (In the formula, R 1are independently unsubstituted or substituted monovalent hydrocarbon groups that do not contain aliphatic unsaturated bonds. X is an alkenyl group, and at least one is contained in one molecule. n is an integer of 0 or greater, m is an integer of 0 or greater, and a is an integer of 0 to 3 independently for each silicon atom to which it is bonded, with at least one of a and m at both ends being an integer of 1 or greater.

[0016] In the formula, R 1 Examples of the unsubstituted or substituted monovalent hydrocarbon group not containing an aliphatic unsaturated bond include those having 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, and more preferably 1 to 6 carbon atoms. Specific examples include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, and dodecyl; cycloalkyl groups such as cyclopentyl, cyclohexyl, and cycloheptyl; aryl groups such as phenyl, tolyl, xylyl, naphthyl, and biphenylyl; and aralkyl groups such as benzyl, phenylethyl, phenylpropyl, and methylbenzyl; and groups in which some or all of the hydrogen atoms bonded to the carbon atoms of these groups have been substituted with halogen atoms such as fluorine, chlorine, or bromine, or with cyano groups, for example, chloromethyl groups, 2-bromoethyl groups, 3-chloropropyl groups, 3,3,3-trifluoropropyl groups, chlorophenyl groups, fluorophenyl groups, cyanoethyl groups, and 3,3,4,4,5,5,6,6,6-nonafluorohexyl groups, with preferred being unsubstituted or substituted alkyl groups having 1 to 3 carbon atoms such as methyl groups, ethyl groups, propyl groups, chloromethyl groups, bromoethyl groups, 3,3,3-trifluoropropyl groups, and cyanoethyl groups, and unsubstituted or substituted phenyl groups such as phenyl groups, chlorophenyl groups, and fluorophenyl groups. 1 As the alkyl group, a methyl group and a phenyl group are preferred.

[0017] In the formula, examples of the alkenyl group for X include those having about 2 to 8 carbon atoms, such as a vinyl group, an allyl group, a propenyl group, an isopropenyl group, a butenyl group, a hexenyl group, and a cyclohexenyl group, and among these, lower alkenyl groups such as a vinyl group and an allyl group are preferred.

[0018] In the formula, n is an integer of 0 or greater, preferably an integer of 10 to 2,000, and more preferably an integer of 50 to 1,200, and m is an integer of 0 or greater, preferably an integer of 0 to 40, and more preferably an integer of 0 to 20. Furthermore, n and m are preferably integers that satisfy 10≦n+m≦2,000, and more preferably 50≦n+m≦1,200, and 0≦m / (n+m)≦0.2. In this case, the units in parentheses enclosed by n and m may be arranged randomly. In the formula, a is an integer of 0 to 3, preferably an integer of 1 to 3, for each silicon atom to be bonded.

[0019] Furthermore, it is preferable that such alkenyl group-containing diorganopolysiloxanes have a viscosity at 23°C of about 10 to 1,000,000 mPa·s, and particularly about 100 to 500,000 mPa·s.

[0020] In the present invention, the number of repeating diorganosiloxane units in a molecule (or degree of polymerization) can be determined as the polystyrene-equivalent number average molecular weight (or number average degree of polymerization) by gel permeation chromatography (GPC) analysis using toluene or the like as a developing solvent. Viscosity can usually be measured at 23°C using a rotational viscometer (e.g., BL type, BH type, BS type, cone-plate type, rheometer, etc.).

[0021] (A) The alkenyl group-containing diorganopolysiloxane may be used alone or in combination of two or more. Also, in order not to impair the function of the platinum-based catalyst mixture of component (D) described later, it is advisable to reduce the amount of oxygen and moisture contained in the alkenyl group-containing diorganopolysiloxane of component (A) in advance before blending it into the composition. For example, it may be carried out by methods such as substitution with an inert gas such as nitrogen gas, heating, reduced pressure, or a combination thereof.

[0022] [(B) Organohydrogenpolysiloxane] (B) The organohydrogenpolysiloxane of component (B) is a linear, cyclic, branched or three-dimensional network structure (resin structure) organohydrogenpolysiloxane having at least 2 (usually 2 to 200, preferably about 3 to 100) hydrogen atoms (SiH groups) bonded to silicon atoms in one molecule, and functions as a curing agent (crosslinking agent) for the curable liquid silicone composition of the present invention.

[0023] Examples of such organohydrogenpolysiloxanes include, for example, organohydrogenpolysiloxanes represented by the following average composition formula (2). H b R 2 c SiO (4-b-c) / 2 (2) (In the formula, R 2 is independently an unsubstituted or substituted monovalent hydrocarbon group not containing an aliphatic unsaturated bond, and b and c are numbers such that 0.001 ≦ b ≦ 1.2, 0.8 ≦ c ≦ 2 and 0.8 < b + c ≦ 3, preferably numbers such that 0.05 ≦ b ≦ 1, 1.5 ≦ c ≦ 2 and 1.8 ≦ b + c ≦ 2.7.)

[0024] In the formula, R 2 The unsubstituted or substituted monovalent hydrocarbon group not containing an aliphatic unsaturated bond is the same as R in the general formula (1) 1Examples include those having 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, and more preferably 1 to 7 carbon atoms, and particularly preferred are lower alkyl groups having 1 to 3 carbon atoms such as a methyl group, a phenyl group, and a 3,3,3-trifluoropropyl group.

[0025] Component (B) is preferably a compound that is liquid at room temperature (23°C ± 15°C, hereinafter the same) and has 2 to 300, particularly 2 to 150, and especially about 2 to 100 silicon atoms per molecule. The hydrogen atoms bonded to the silicon atoms (SiH groups) may be located at either the terminals of the molecular chain, midway along the molecular chain (non-terminal), or both.

[0026] Examples of such organohydrogenpolysiloxanes include methylhydrogencyclosiloxane oligomers such as 1,1,3,3-tetramethyldisiloxane, 1,1,3,3,5,5-hexamethyltrisiloxane, 1,3,5,7-tetramethyltetracyclosiloxane, and 1,3,5,7,9-pentamethylpentacyclosiloxane; tris(dimethylhydrogensiloxy)methylsilane; tris(dimethylhydrogensiloxy)phenylsilane; methylhydrogenpolysiloxanes terminated at both molecular chain ends with trimethylsiloxy groups; dimethylsiloxane-methylhydrogensiloxane copolymers terminated at both molecular chain ends with trimethylsiloxy groups; diphenylsiloxane-methylhydrogensiloxane copolymers terminated at both molecular chain ends with trimethylsiloxy groups; and methylphenylsiloxane-methylhydrogensiloxanes terminated at both molecular chain ends with trimethylsiloxy groups. Copolymer, dimethylsiloxane-diphenylsiloxane-methylhydrogensiloxane copolymer terminated at both molecular chain ends with trimethylsiloxy groups, dimethylpolysiloxane terminated at both molecular chain ends with dimethylhydrogensiloxy groups, methylhydrogenpolysiloxane terminated at both molecular chain ends with dimethylhydrogensiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymer terminated at both molecular chain ends with dimethylhydrogensiloxy groups, diphenylsiloxane-methylhydrogensiloxane copolymer terminated at both molecular chain ends with dimethylhydrogensiloxy groups, methylphenylsiloxane-methylhydrogensiloxane copolymer terminated at both molecular chain ends with dimethylhydrogensiloxy groups, dimethylsiloxane-diphenylsiloxane-methylhydrogensiloxane copolymer terminated at both molecular chain ends with dimethylhydrogensiloxy groups, dimethylhydrogensiloxy units and SiO 4 / 2Examples of suitable organosilicon compounds include silicone resins having a three-dimensional network structure consisting of units, which may optionally contain trimethylsiloxy units, dimethylsiloxane units, methylhydrogensiloxane units, hydrogensilsesquioxane units, and / or methylsilsesquioxane units, and compounds in which some or all of the methyl groups in the above-mentioned exemplary compounds have been substituted with other alkyl groups or phenyl groups. Note that component (B) and the organosilicon compound in component (D), which will be described later, may be the same.

[0027] The organohydrogenpolysiloxane used in the composition of the present invention can be obtained by known methods, for example, a compound represented by the following general formula: 2 SiHCl2 and R 2 2SiHCl (where R 2 is the same as above.) or by (co)hydrolytic condensation of the chlorosilane with a compound represented by the following general formula: R 2 3SiCl and R 2 2SiCl2 (wherein, R 2 are the same as above.) and at least one chlorosilane selected from the group consisting of chlorosilanes ...

[0028] From the viewpoint of providing a good silicone rubber and gel upon curing, the amount of organohydrogenpolysiloxane (B) blended is an amount such that the number of hydrogen atoms bonded to silicon atoms (i.e., SiH groups) in the organohydrogenpolysiloxane of component (B) is 0.5 to 4 moles, and preferably 0.8 to 2.5 moles, per mole of alkenyl groups in the alkenyl-group-containing diorganopolysiloxane of component (A).

[0029] The organohydrogenpolysiloxane of component (B) may be used alone or in combination of two or more. In order to avoid impairing the function of the aerobic platinum-based catalyst mixture of component (D), which will be described later, it is advisable to reduce the oxygen and water contents in the organohydrogenpolysiloxane of component (B) before blending it into the composition. This can be done, for example, by replacing the atmosphere with an inert gas such as nitrogen gas, by heating or reducing the pressure, or by a combination of these methods.

[0030] [(C) Platinum-based catalyst activated by ultraviolet light] Component (C) in the curable liquid silicone composition of the present invention is a platinum-based catalyst that is activated by light with a wavelength of 200 to 500 nm, preferably ultraviolet light with a wavelength of 200 to 400 nm. In other words, it is a catalyst that is inactive in the dark and that, when irradiated with light with a wavelength of 200 to 500 nm, preferably ultraviolet light with a wavelength of 200 to 400 nm, changes to a platinum-based catalyst (hydrosilylation addition reaction catalyst) that is active at room temperature, thereby accelerating the hydrosilylation addition reaction between alkenyl groups in component (A) and silicon-bonded hydrogen atoms in component (B).

[0031] As the platinum catalyst activated by ultraviolet light, which is component (C), platinum acetylacetonato complexes and platinum cyclopentadienyl complexes, etc., as disclosed in U.S. Pat. Nos. 4,510,094 and 4,530,879, etc., are used. Specific examples of such component (C) include (η 5 and complexes of tri-aliphatic platinum compounds, of which cyclopentadienyltrimethylplatinum complex and methylcyclopentadienyltrimethylplatinum complex are preferred. Further examples include complexes of bis(β-diketonato)platinum compounds, of which bis(acetylacetonato)platinum complexes are preferred.

[0032] The amount of platinum catalyst in component (C) is 0.1 to 1,000 ppm, preferably 0.1 to 500 ppm, and more preferably 0.1 to 50 ppm, of platinum atoms contained in component (C) relative to the total mass of components (A) and (B). If the amount of component (C) is less than this range, the curing reaction rate may be insufficient or the composition may not cure due to the influence of surrounding curing inhibitors. If the amount is more than this range, sufficient shelf life may not be achieved.

[0033] The component (C) may be used alone or in combination of two or more types. Furthermore, when using component (C), if it is a solid catalyst it can be used in solid form; however, to obtain a more uniform cured product, it is preferable to use the catalyst dissolved in an appropriate solvent, such as toluene, xylene, ethyl acetate, or 2-(2-butoxyethoxy)ethyl acetate.

[0034] [(D) Platinum-based catalyst mixture activated by moisture and / or oxygen] The moisture- and / or oxygen-activated platinum catalyst mixture of component (D) is activated by contact with moisture and / or oxygen, particularly atmospheric moisture (humidity) and / or oxygen, and acts as a hydrosilylation addition reaction catalyst. It is an aerobic platinum catalyst mixture comprising a reaction mixture of a platinum-alkenyl group-containing organosiloxane complex and an organosilicon compound having at least one silicon-bonded hydrogen atom (SiH group) per molecule in such an amount that the silicon-bonded hydrogen atom (SiH group) is in molar excess (molar ratio of greater than 1) relative to the alkenyl groups in the platinum-alkenyl group-containing organosiloxane complex. In the present invention, "aerobic" refers to a property (aerobic reaction type) in which the catalytic activity as a hydrosilylation addition reaction catalyst is low in a sealed state with a low oxygen concentration (substantially no oxygen) and low moisture content, where contact with moisture (humidity) and oxygen is blocked, but the catalyst is activated as a hydrosilylation addition reaction catalyst upon contact with moisture (humidity) and / or oxygen in the atmosphere. Here, "atmosphere" refers to an oxygen concentration of 21% by volume and a humidity of more than 5% RH and not more than 100% RH. A low oxygen concentration in a sealed state refers to an oxygen concentration of 0.1% by volume or less, and a low moisture content refers to a humidity of 5% RH or less. Furthermore, "sealed state (or under sealing)" refers to a state in which contact with the atmosphere is blocked (i.e., contact with moisture (humidity) and oxygen is blocked), and a sealed container refers to a container that achieves this sealed state.

[0035] In the platinum catalyst mixture of component (D), the platinum-alkenyl group-containing organosiloxane complex is preferably a complex of platinum, platinum chloride, chloroplatinic acid, or a chloroplatinate salt with a vinyl group-containing siloxane (e.g., an organodisiloxane compound having two alkenyl groups per molecule, such as 1,3-divinyl-1,1,3,3-tetramethyldisiloxane). For example, in the case of a complex of chloroplatinic acid (HPtCl) and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, three molecules of the bidentate ligand 1,3-divinyl-1,1,3,3-tetramethyldisiloxane are coordinated to one molecule of chloroplatinic acid.

[0036] The platinum-alkenyl group-containing organosiloxane complex is preferably used by dissolving it in a solvent such as toluene, a lower alcohol, a higher alcohol, a silicone-based solvent, etc. In this case, the platinum atom content (concentration) in the solution is preferably 0.05 to 5 mass %.

[0037] In the platinum catalyst mixture of component (D), the organosilicon compound having at least one silicon-bonded hydrogen atom (SiH group) per molecule can be an organohydrogensilane, organohydrogensiloxane oligomer, or the like, each having at least one SiH group per molecule (e.g., 1 to 10, preferably 1 to 5). From the standpoints of ease of handling and safety, organohydrogensiloxane oligomers are more preferred. The molecular structure of this organohydrogensiloxane oligomer may be linear or cyclic, and the number of silicon atoms per molecule is preferably 2 to 40, more preferably 2 to 10, and even more preferably 2 to 5.

[0038] Examples of organohydrogensilanes and organohydrogensiloxane oligomers used in the present invention include trialkoxy(hydrogen)silanes, alkyldialkoxy(hydrogen)silanes, dialkylalkoxy(hydrogen)silanes, 1,1,1,3,3-pentamethyldisiloxane, 1,1,3,3-tetramethyldisiloxane, 1,1,1,3,5,5,5-heptamethyltrisiloxane, 1,1,3,3,5,5-hexamethyltrisiloxane, 1,1,1,3,5,7,7,7-octamethyltetrasiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, and 1,3,5,7,9-pentamethylcyclopentasiloxane. These compounds may be used alone or in combination of two or more.

[0039] The platinum catalyst mixture of component (D) is a reaction mixture in which the alkenyl groups in the platinum-alkenyl group-containing organosiloxane complex react with the SiH groups derived from the organosilicon compound, which is added in excess molar amount relative to the alkenyl groups during preparation of the mixture (i.e., more than 1 mole, preferably about 1.1 to 30 moles, more preferably about 1.5 to 25 moles, and even more preferably about 5 to 25 moles per mole of alkenyl groups), in a moisture- and oxygen-free atmosphere (for example, a sealed environment with a low oxygen concentration (substantially no oxygen) and low moisture content, where contact with moisture (humidity) and oxygen is blocked), resulting in all of the alkenyl groups being converted to alkylene groups via a hydrosilylation addition reaction (the alkenyl groups have essentially disappeared), and in which excess SiH groups derived from the organosilicon compound remain in the mixture.

[0040] The method for preparing the platinum catalyst mixture of component (D) involves mixing the platinum-alkenyl group-containing organosiloxane complex and the organosilicon compound having at least one silicon-bonded hydrogen atom (SiH group) per molecule in a proportion such that the SiH groups of the organosilicon compound are in molar excess relative to the alkenyl groups in the platinum-alkenyl group-containing organosiloxane complex in a moisture- and oxygen-free atmosphere to obtain a reaction mixture.

[0041] Here, the blending ratio in which the SiH groups of the organosilicon compound having at least one hydrogen atom (SiH group) bonded to a silicon atom per molecule relative to the alkenyl groups in the platinum-alkenyl group-containing organosiloxane complex are in excess molar amount means that the blending amounts of the platinum-alkenyl group-containing organosiloxane complex and the organosilicon compound are such that the SiH groups in the organosilicon compound are greater than 1 mole, preferably 1.1 to 30 moles, more preferably 1.5 to 25 moles, and even more preferably about 5 to 25 moles, relative to 1 mole of alkenyl groups in the complex.

[0042] The mixing method is not particularly limited as long as it is a method that uniformly mixes the platinum-alkenyl group-containing organosiloxane complex and the organosilicon compound having at least one hydrogen atom bonded to a silicon atom (SiH group) per molecule, but it is preferable to use, for example, a glass reactor such as a glass flask or a stainless steel reactor.

[0043] The mixing atmosphere is preferably moisture- and oxygen-free, and is preferably an inert gas atmosphere such as nitrogen or reduced pressure (vacuum). The temperature during mixing does not need to be elevated, and room temperature is acceptable. The mixing time (i.e., reaction time) may be any time required to uniformly mix the platinum-alkenyl group-containing organosiloxane complex and the organosilicon compound having at least one silicon-bonded hydrogen atom (SiH group) per molecule, and is preferably, for example, 0.5 to 100 hours, particularly 1 to 24 hours.

[0044] Furthermore, in the platinum-based catalyst mixture of component (D), when the organosilicon compound having at least one hydrogen atom bonded to a silicon atom (SiH group) per molecule is an organohydrogensiloxane oligomer having at least two hydrogen atoms (hereinafter sometimes referred to as adjacent SiH groups) bonded to adjacent silicon atoms (hereinafter sometimes referred to as adjacent silicon atoms) via ether oxygen atoms that form a siloxane bond (Si-O-Si) per molecule (for example, when the organosilicon compound is 1,1,3,3-tetramethyldisiloxane, 1,1,1,3,5,7,7,7-octamethyltetrasiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, 1,3,5,7,9-pentamethylcyclopentasiloxane, etc.), In the latter case, the reaction mixture is preferably prepared by uniformly mixing the organohydrogensiloxane oligomer having at least two vicinal SiH groups and the platinum-alkenyl group-containing organosiloxane complex in a moisture- and oxygen-free atmosphere, and then contacting the resulting mixture with moisture and / or oxygen by means of mixing in the air, or by mixing the organohydrogensiloxane oligomer having at least two vicinal SiH groups and the platinum-alkenyl group-containing organosiloxane complex in a blending ratio such that the SiH groups in the organohydrogensiloxane oligomer having at least two vicinal SiH groups are in molar excess relative to the alkenyl groups in the platinum-alkenyl group-containing organosiloxane complex, while in contact with moisture and / or oxygen. As a result, a curable liquid silicone composition containing this mixture as a hydrosilylation addition reaction catalyst can be stored in a sealed state for an extended period of time as a one-component product without losing its curability when exposed to moisture (humidity) and / or oxygen in the atmosphere, as long as the system (composition) is substantially free of moisture and oxygen during storage.

[0045] When the organosilicon compound having at least one silicon-bonded hydrogen atom (SiH group) per molecule is an organohydrogensiloxane oligomer having at least two hydrogen atoms (vicinal SiH groups) per molecule, each bonded to adjacent silicon atoms via an ether oxygen atom forming a siloxane bond (Si-O-Si), the preparation method preferably includes a step of further mixing the reaction mixture obtained by mixing in a moisture- and oxygen-free atmosphere while contacting it with moisture and / or oxygen. This step involves contacting the reaction mixture with moisture and / or oxygen by means of mixing in air, for example. The mixing time in air is preferably 0.5 to 100 hours, particularly 1 to 12 hours. The platinum-based catalyst mixture is then placed in a sealed container.

[0046] Furthermore, when the organosilicon compound having at least one hydrogen atom (SiH group) bonded to a silicon atom in one molecule is an organohydrogensiloxane oligomer having at least two hydrogen atoms (adjacent SiH groups) bonded to adjacent silicon atoms via ether oxygen atoms forming a siloxane bond (Si-O-Si) in one molecule, another preparation method is to mix a platinum-alkenyl group-containing organosiloxane complex with the organohydrogensiloxane oligomer in the above-mentioned mixing ratio, in which the SiH groups of the organohydrogensiloxane oligomer are in excess molar relative to the alkenyl groups in the platinum-alkenyl group-containing organosiloxane complex, in a state of contact with moisture and / or oxygen.By this preparation method, the above components are brought into contact with moisture and / or oxygen by means of mixing in the atmosphere, for example, and the mixing time in the atmosphere is preferably 0.5 to 100 hours, particularly preferably 1 to 12 hours. Thereafter, the platinum-based catalyst mixture is placed in a sealed container.

[0047] The component (D) may be used alone or in combination of two or more types. The amount of the platinum catalyst mixture in component (D) is an amount that corresponds to 0.1 to 1,000 ppm, and preferably 0.5 to 200 ppm, calculated as the mass of platinum atoms contained in component (D) relative to the combined mass of components (A) and (B). If the amount of component (D) is less than this range, the curable liquid silicone composition will not cure sufficiently due to the influence of catalyst inhibitors, while if the amount is greater than this range, the storage stability will be poor. Furthermore, because the blending amount of component (D) is a so-called catalytic amount, any excess molar amount of SiH groups remaining in component (D) is negligibly small and does not substantially affect the molar ratio of SiH groups in component (B) to alkenyl groups in component (A) described above.

[0048] [Other ingredients] In addition to the above components (A) to (D), the curable liquid silicone composition of the present invention can contain various optional components as described below, as needed, provided that the object of the present invention is not impaired.

[0049] [(E) Dehydrating agent] The curable liquid silicone composition of the present invention can further contain, as an optional component, a dehydrating agent (component (E)) to remove water from the composition, as needed. By incorporating a dehydrating agent (component (E)), it is possible to obtain even better storage stability.

[0050] As mentioned above, the platinum catalyst mixture of component (D), which is one of the core technologies of the present invention, has the property that its catalytic activity is kept low in low-oxygen concentration (substantially oxygen-free) and low-moisture environments where contact with moisture (humidity) and oxygen is blocked, and its catalytic function as a hydrosilylation addition reaction catalyst is activated upon contact with moisture and / or oxygen from the outside air (atmosphere) (aerobic reaction type). For this reason, it has been confirmed that reducing the amount of moisture in each component and in the mixed composition improves the shelf life of the one-component curable liquid silicone composition, and introducing a mechanism (dehydration using a dehydrating agent (E)) that consumes moisture from each component in the composition and trace amounts of moisture that enter from outside the container within the composition when stored in a sealed container is useful in ensuring the shelf life of the one-component.

[0051] The dehydrating agent for component (E) may be either an inorganic or organic compound, provided that it does not impair the functions of components (A), (B), (C), and (D). However, depending on the dehydrating agent, compounds produced as by-products in the dehydration reaction may cause foaming. Furthermore, many dehydrating agents may also cause decomposition of the organohydrogenpolysiloxane of component (B) or the organosilicon compound containing at least one silicon-bonded hydrogen atom (SiH group) per molecule contained in component (D), or may reduce the catalytic activity of the platinum-based catalyst mixture of component (D).

[0052] Therefore, silyl ketenes (including silyl ketene acetals), silyl enol esters, and α-silyl esters are suitable as dehydrating agents for component (E), as they enable efficient in-situ dehydration. These compounds have a structure in which the by-products produced during dehydration do not impair the functions of components (A), (B), (C), and (D). Furthermore, they dissolve in the curable liquid silicone composition, allowing for the formation of a stable curable liquid silicone composition. Among these, silyl ketenes (including silyl ketene acetals) and α-silyl esters undergo dehydration reactions under non-basic conditions, and therefore do not decompose the organohydrogenpolysiloxane (component (B)) or organosilicon compounds containing at least one silicon-bonded hydrogen atom (SiH group) per molecule contained in component (D), or reduce the catalytic activity of the platinum-based catalyst mixture (component (D)).

[0053] Examples of silyl ketenes (containing silyl ketene acetals) include 1-methoxy-2-methyl-1-(trimethylsiloxy)propene, dimethyl ketene trimethylsilyl acetal, and tert-butoxy-1-(trimethylsiloxy)propene.

[0054] Examples of α-silyl esters include ethyl 2-(trimethoxysilyl)propionate (ECMS) and octyl 2-(methyldimethoxysilyl)propionate (OCMS-2).

[0055] The dehydrating agent (component E) may be added to each component beforehand, during the preparation of the composition, or after the composition has been prepared. The amount added is preferably 0.01 to 5 mass %, particularly 0.1 to 2 mass %, of the total composition. Addition of too much component E may adversely affect the heat-resistant physical properties of the cured product.

[0056] A catalyst may also be added to promote the reaction between component (E) and water. Examples of such catalysts include titanate esters (such as tetra(isopropyl)titanate (TPT), tetrabutyltitanate (TBT), and tetra(2-ethylhexyl)titanate (TOT)), titanium chelate compounds (such as titanium diisopropoxybis(ethylacetoacetate) and titanium tetraacetylacetonate), and tin compounds (such as dibutyldimethoxytin and dibutyltin dilaurate). The amount of catalyst added is preferably 0.001 to 2% by mass, and particularly preferably 0.01 to 1% by mass, of the total composition.

[0057] [(F) Hydrosilylation Addition Reaction Control Agent] It is also useful to further incorporate, as an optional component, a hydrosilylation addition reaction inhibitor (Component (F)) into the curable liquid silicone composition of the present invention, if necessary, for the purpose of improving the shelf life of the one-part composition.

[0058] As described above, the platinum-based catalysts of components (C) and (D) of the composition of the present invention have the property that their catalytic function is activated by exposure to ultraviolet light or contact with moisture and / or oxygen. Therefore, a portion of the platinum-based catalysts of components (C) and (D) may be activated as hydrosilylation addition reaction catalysts due to trace amounts of ultraviolet light to which the composition is exposed during preparation, moisture in the components, moisture introduced during the composition preparation process or container filling process, and ultraviolet light, oxygen, and moisture entering from outside the light-shielded, sealed container. This activated catalyst may significantly reduce the shelf life of the one-part composition. However, the addition of a hydrosilylation addition reaction inhibitor (component (F)) as a supplementary agent can prevent such a decrease in shelf life.

[0059] Hydrosilylation addition reaction inhibitors include acetylene alcohols such as 1-ethynylcyclohexanol and 3-methyltridec-1-yn-3-ol (EMDC), silanes of acetylene alcohols such as dimethylbis(1,1-dimethyl-2-propynyloxy)silane (PLR-22) and 3-(trimethylsilyloxy)-3-methyl-1-butyne (PLR-31), siloxane-modified products, tri(isopropyl)phosphite, tris(di-tert-butylphenyl)phosphite, triphenylphosphite, tris(2-ethylhexyl)phosphite, Examples of suitable compounds include compounds selected from the group consisting of phosphorous acid compounds (particularly phosphite esters) such as tri(isopropyl)phosphite and tris(di-tert-butylphenyl)phosphite, ethylenediamines such as tetramethylethylenediamine, benzotriazoles such as 5-methyl-1H-benzotriazole, and mixtures thereof. In particular, phosphorous acid compounds, particularly the phosphorous acid esters tri(isopropyl)phosphite and tris(di-tert-butylphenyl)phosphite are preferred, as they provide curable liquid silicone compositions that have good one-component storage stability when protected from light and sealed.

[0060] The amount of hydrosilylation addition inhibitor (F) added may be any amount that does not affect the curability of the composition of the present invention, depending on the performance of the respective hydrosilylation addition inhibitor. However, it is preferable to add an amount that does not impair the curability due to the secondary hydrosilylation addition reaction promoted by the platinum-based catalyst mixture (D) activated by exposure to air (moisture and / or oxygen) after UV irradiation. In the case of phosphorous compounds such as phosphites, the amount added may be small, less than 1 mole per mole of platinum atoms contained in the composition, and preferably about 0 to 0.75 moles. If present, an amount of 0.1 moles or more per mole of platinum atoms contained in the composition is preferred. If the amount of component (F) added is too high, it may deactivate both the platinum-based catalyst (C) activated by UV light during use and the platinum-based catalyst (D) activated by moisture and / or oxygen during use, thereby reducing the curability when exposed to the atmosphere.

[0061] In addition to the optional components (E) dehydrating agent and (F) hydrosilylation addition reaction inhibitor described above, the curable liquid silicone composition of the present invention may also contain other optional components, such as inorganic fillers, adhesion promoters, pigment pastes, and reinforcing silicone resins, as needed.

[0062] The curable liquid silicone composition of the present invention can be stored in a light-shielding, airtight container that is capable of blocking ultraviolet light and blocking or reducing the intrusion of oxygen and moisture, particularly atmospheric moisture (humidity) and oxygen, thereby achieving superior one-component shelf life, which allows the composition to be distributed and sold as a one-component curable liquid silicone composition. Furthermore, when the curable liquid silicone composition of the present invention is opened from its light-tight, sealed container and irradiated with ultraviolet light at room temperature, the ultraviolet-irradiated areas will harden, and when the composition is then exposed to the atmosphere and brought into contact with atmospheric moisture (humidity) and / or oxygen at room temperature, not only the surface in contact with the air but also the areas not irradiated with ultraviolet light (shadow areas) and even the shadow areas that are not reached by ultraviolet light will rapidly harden to give a cured silicone rubber or cured silicone gel.

[0063] [Method for curing the curable liquid silicone composition] The method for curing the curable liquid silicone composition of the present invention comprises the following steps. (1) A step of irradiating the curable liquid silicone composition with ultraviolet light at room temperature. (2) Thereafter, the substrate is exposed to the atmosphere at room temperature for a predetermined period of time.

[0064] [Ultraviolet irradiation process] The first step of the curing method of the present invention is to irradiate the curable liquid silicone composition of the present invention with ultraviolet light at room temperature (23°C±15°C), preferably with light of 200 to 500 nm at room temperature. By irradiating with ultraviolet light, the platinum-based catalyst of component (C) in the ultraviolet-irradiated portion is activated and acts as a hydrosilylation addition reaction catalyst, accelerating the hydrosilylation addition reaction and curing the ultraviolet-irradiated portion. The lamp for irradiating ultraviolet light is not particularly limited as long as it can supply ultraviolet light with a wavelength of 200 to 500 nm, and examples thereof include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, xenon lamps, metal halide lamps, ultraviolet LED lamps, etc. The amount of ultraviolet light irradiation varies depending on the type and amount of photoactive platinum complex (platinum-based catalyst of component (C)) used, but it is sufficient as long as it is an amount sufficient to activate the photoactive platinum complex, and is 10 to 1,000 mW / cm. 2 , especially 20-400mW / cm 2 It is preferable to irradiate the ultraviolet light having the above intensity for 0.1 seconds to 5 minutes, particularly for 0.5 seconds to 1 minute.

[0065] [Atmospheric exposure process] The curing method of the present invention involves, as a second step, exposing the composition to the atmosphere at room temperature for a predetermined time after the above-mentioned ultraviolet irradiation step. The curable liquid silicone composition of the present invention described above is irradiated with ultraviolet light at room temperature (23°C±15°C) to cure through a hydrosilylation addition reaction by component (C), which has been activated, and then further exposing the composition to the atmosphere at room temperature for a predetermined time (usually 0.5 hours or more, preferably 1 to 48 hours, more preferably 2 to 24 hours). This activates the platinum catalyst mixture of component (D) and causes it to act as a hydrosilylation addition reaction catalyst, further promoting the hydrosilylation addition reaction and thereby curing particularly areas shaded by the ultraviolet irradiation and areas that are not reached by the ultraviolet light.

[0066] The silicone rubbers and silicone gels obtained as the cured products of the curable liquid silicone composition of the present invention thus obtained have excellent heat resistance and electrical insulation properties, and are applicable to automotive parts, aircraft, home appliances, and the like. [Example]

[0067] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. The viscosity is measured at 23°C using a rotational viscometer, and the degree of polymerization is the number-average degree of polymerization in terms of polystyrene measured by GPC analysis using toluene as the developing solvent. Me represents a methyl group, and Vi represents a vinyl group. "Room temperature" means 23°C.

[0068] [Examples 1 to 4, Comparative Examples 1 to 3] A curable liquid silicone composition was prepared as follows. (Preparation of Curable Liquid Silicone Composition) Each composition was prepared by uniformly mixing the components in the amounts shown in Table 2 below in a brown glass bottle under a nitrogen atmosphere at room temperature (23°C) and sealing the bottle in a dark place. The molar ratio of SiH groups in component (B) to vinyl groups in component (A) was 2.2. The ingredients were added in the following order while mixing: (A) alkenyl-containing diorganopolysiloxane, (B) organohydrogenpolysiloxane, (E) dehydrating agent, (F) hydrosilylation addition reaction inhibitor, (C) platinum-based catalyst activated by ultraviolet light, and (D) platinum-based catalyst mixture activated by moisture and / or oxygen. If any component was not added, that component was skipped and the addition of the subsequent components continued. To ensure reproducible preparation of the composition, (A) the alkenyl-containing diorganopolysiloxane and (B) the organohydrogenpolysiloxane were each previously dehydrated by degassing under reduced pressure in a glass flask at 120° C. The mixing and container-filling steps for the composition were carried out under a nitrogen atmosphere.

[0069] The components are as follows: (A) Alkenyl group-containing diorganopolysiloxane: A vinyl-containing linear diorganopolysiloxane with a viscosity of 5,000 mPa·s at 23°C, as shown by the average formula below: [ka]

[0070] (B) Organohydrogenpolysiloxane: A linear organohydrogenpolysiloxane represented by the following average formula: [ka]

[0071] (C) Platinum-based catalysts activated by ultraviolet light: (C-1) Toluene solution of methylcyclopentadienyltrimethylplatinum complex (platinum content 0.5% by mass) (C-2) 2-(2-butoxyethoxy)ethyl acetate solution of bisacetylacetonatoplatinum complex (platinum content 0.5% by mass)

[0072] (D) Aerobic platinum-based catalyst mixture: The aerobic platinum-based catalyst mixtures (D-1) and (D-2) prepared as follows were used. In a nitrogen atmosphere at room temperature (23°C), 8.0 g of a toluene solution of a platinum-alkenyl group-containing organosiloxane complex (platinum atom content 0.5% by mass) and 2.0 g of 1,1,3,3-tetramethyldisiloxane were mixed and reacted uniformly in a 25 g glass bottle for 12 hours, and then sealed to prepare an aerobic platinum-based catalyst mixture (D-1). The lid of the glass bottle was then opened in the air at room temperature (23°C), and the mixture was further mixed uniformly while in contact with the air for another 2 hours, and then sealed to prepare an aerobic platinum-based catalyst mixture (D-2).

[0073] [Table 1]

[0074] (E) Dehydrating agent: Ethyl 2-(trimethoxysilyl)propionate (ECMS) (α-silyl esters) (E') A catalyst that promotes the reaction of component (E) with moisture: Tetra(isopropyl)titanate (TPT)

[0075] (F) Hydrosilylation addition reaction inhibitor: Tris(di-tert-butylphenyl)phosphite (0.31% by mass toluene solution) represented by the following formula [ka]

[0076] The curable liquid silicone compositions thus prepared were evaluated for cured product appearance, one-component storage stability under light-shielded and sealed conditions, curability after UV irradiation after storage, and shadow curability as follows.

[0077] [Appearance of cured product] The appearance of the cured product was evaluated by visual inspection, and was colorless and transparent to pale yellow and transparent in each of the Examples and Comparative Examples.

[0078] [One-liquid storage stability (light-shielded / sealed)] To evaluate the one-component shelf life, the curable liquid silicone composition was filled into a brown glass bottle under a nitrogen atmosphere and sealed, and then the brown glass bottle was left in the air / room temperature, and the thickening and gelling behavior of the curable liquid silicone composition was observed.At this time, the thickening and gelling behavior of the curable liquid silicone composition was observed by tilting the brown glass bottle and observing the degree to which the composition in the brown glass bottle followed the tilt (fluidity), and when the fluidity became worse than immediately after sealing, it was judged that the curable liquid silicone composition had thickened or gelled.In addition, at this time, the brown glass bottle containing the sealed curable liquid silicone composition was left in the air / room temperature, and then observed for 5 minutes, and then observed every day to determine the time (minutes, days) until the curable liquid silicone composition thickened or gelled.

[0079] For evaluation of curability after UV irradiation and curability in shadow areas (areas not irradiated with UV), a curable liquid silicone composition that had been stored in a sealed brown glass bottle for one day was used, as described above.

[0080] [Cureability after UV irradiation] Curability after UV irradiation was evaluated by casting 25 g of each composition prepared in the Examples and Comparative Examples into an aluminum dish with a diameter of 60 mm and a depth of 1 mm, and irradiating the composition at 23°C with a UV-LED lamp with a wavelength of 365 nm at an irradiation intensity of 100 mW / cm. 2 and a dose of 3,000 mJ / cm 2After irradiating with ultraviolet light so as to achieve a curing temperature of 23°C, the composition was allowed to stand in the air at 23°C to cure, and the state of cure was confirmed. For evaluation, the hardness (Type A durometer) specified in JIS K 6249 was measured for rubber-like cured products that could be measured. For products that could not be measured, visual observation was performed. Observation was performed 10 minutes, 1 hour, 6 hours, and 24 hours after UV irradiation.

[0081] [Shadow hardening] Shadow curing (without UV irradiation) was performed by placing an aluminum plate (25 mm × 50 mm) with 1 mm spacers on both ends in an aluminum dish with a diameter of 60 mm and a depth of 1 mm, and then casting 25 g of each composition prepared in the Examples and Comparative Examples into multiple samples. The samples were then irradiated at 23°C with a UV-LED lamp with a wavelength of 365 nm and an irradiation intensity of 100 mW / cm. 2 and a dose of 3,000 mJ / cm 2 After irradiating with ultraviolet light so that the composition was cured, the composition was allowed to stand in the air at 23°C, and the state of curing on the back side of the aluminum plate was visually confirmed 10 minutes, 1 hour, 6 hours, and 24 hours after ultraviolet irradiation.

[0082] [Table 2]

[0083] The above results confirm that the curable liquid silicone composition of the present invention has excellent one-component storage stability in a light-shielded, airtight container, and that after UV irradiation, the platinum-based catalyst in the irradiated areas is activated, causing a hydrosilylation addition reaction to proceed.Furthermore, after leaving the composition to stand in the atmosphere, the platinum-based catalyst mixture in the shaded areas is activated, causing a hydrosilylation addition reaction to proceed, resulting in curing into a rubber or gel.

Claims

1. (A) a diorganopolysiloxane having at least one alkenyl group per molecule; (B) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms per molecule: an amount such that there are 0.5 to 4 moles of silicon-bonded hydrogen atoms in component (B) per mole of alkenyl groups in component (A); (C) an ultraviolet-activated platinum-based catalyst: an amount equivalent to 0.1 to 1,000 ppm by mass of platinum atoms in component (C) relative to the total mass of component (A) and component (B); (D) a platinum-based catalyst mixture activated by moisture and / or oxygen: an amount equivalent to 0.1 to 1,000 ppm by mass of platinum atoms in component (D) relative to the total mass of components (A) and (B) A method for producing a curable liquid silicone composition comprising: A method for producing a curable liquid silicone composition includes the steps of: mixing, as component (D), a platinum-alkenyl group-containing organosiloxane complex with an organohydrogensiloxane oligomer having per molecule at least two hydrogen atoms bonded to adjacent silicon atoms (adjacent SiH groups) via ether oxygen atoms that form siloxane bonds (Si—O—Si), in an amount such that the number of hydrogen atoms bonded to silicon atoms is in molar excess relative to the alkenyl groups in the platinum-alkenyl group-containing organosiloxane complex; and contacting the resulting mixture with moisture and / or oxygen to obtain a reaction mixture.

2. A method for producing a curable liquid silicone composition as described in claim 1, wherein the curable liquid silicone composition is a one-component composition.

3. 2. The method for producing a curable liquid silicone composition according to claim 1, wherein the organohydrogensiloxane oligomer is 1,1,3,3-tetramethyldisiloxane, 1,1,1,3,5,7,7,7-octamethyltetrasiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, or 1,3,5,7,9-pentamethylcyclopentasiloxane.

4. A method for producing a curable liquid silicone composition according to claim 1, wherein the curable liquid silicone composition further contains (E) a dehydrating agent in an amount of 0.01 to 5 mass % of the total composition.

5. A method for producing a curable liquid silicone composition according to claim 1, wherein the curable liquid silicone composition further contains (F) a hydrosilylation addition reaction inhibitor in an amount of 0.1 to 1 mole per mole of platinum atoms contained in the composition.

6. A method for curing a curable liquid silicone composition, comprising the steps of irradiating a curable liquid silicone composition produced by the method for producing a curable liquid silicone composition according to any one of claims 1 to 5 with ultraviolet light at room temperature, and then exposing the composition to the atmosphere for a predetermined period of time.

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