Method for preparing platinum catalyst mixture

Abstract

An aerobic platinum catalyst mixture comprising a reaction mixture of a platinum-alkenyl group-containing organosiloxane complex and an organic silicon compound having at least one SiH group per molecule in an amount that makes a molar excess of hydrogen atoms bonded to silicon atoms (SiH groups) relative to the alkenyl groups in the platinum-alkenyl group-containing organosiloxane complex. The platinum catalyst mixture has the property of catalytic activity being low as a hydrosilylation addition reaction catalyst when in an oxygen-free, low-moisture content closed state in which contact with moisture (humidity) and oxygen is cut off and being activated as a hydrosilylation addition reaction catalyst by contact with moisture (humidity) and / or oxygen in the atmosphere.

Description

[Technical field]

[0001] The present invention relates to an aerobic platinum catalyst mixture that is activated as a hydrosilylation addition reaction catalyst by contact with atmospheric moisture (humidity) and / or oxygen. of It relates to a preparation method. [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 liquid silicone compositions that can be cured without heating. In addition, one-component materials are preferred for the sake of ease of use and to prevent mistakes during use.

[0003] In liquid silicone compositions, the crosslinking reactions that are one-part and can be cured without heating include condensation reactions, UV radical reactions, and addition reactions, some of which have extremely short shelf life and some of which can activate the catalyst with UV. However, all of these reactions have insufficient deep curing properties or curing properties in dark areas exposed to UV light, limiting the applications in which they can be used. In addition, when UV irradiation is required, electricity and energy are required for this purpose.

[0004] Among the technologies for curing silicone compositions into rubber or gel through a crosslinking reaction that utilizes an addition reaction with a platinum catalyst, the following prior art technologies aim to ensure the one-part storage stability and pot life of the unreacted composition and to cure at lower temperatures; however, none of them enable one-part storage stability under airtightness at a level suitable for sale and distribution, or room temperature curing after opening. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Pat. No. 3,989,666 [Patent Document 2] U.S. Pat. No. 3,989,667 [Patent Document 3] U.S. Pat. No. 4,510,094 [Patent Document 4] Japanese Patent Application Publication No. 9-143373 [Patent Document 5] Japanese Patent Application Publication No. 6-192576 [Patent Document 6] Japanese Patent Application Publication No. 9-141107 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 an aerobic platinum catalyst mixture that is activated as a hydrosilylation addition reaction catalyst by contact with the atmosphere (air), more specifically, by contact with moisture (humidity) and / or oxygen in the atmosphere. of The present invention aims to provide a method for preparation thereof. [Means for solving the problem]

[0007]

[0011] As a result of intensive research by the present inventors in order to solve the above-mentioned problems, they have found that a reaction mixture obtained by uniformly mixing a platinum-alkenyl group-containing organosiloxane complex and an organosilicon compound having at least one hydrogen atom bonded to a silicon atom (SiH group, hydrosilyl group) in an oxygen-free atmosphere in a ratio such that there is an excess of molar SiH groups in the organosilicon compound per mole of alkenyl groups in the platinum-alkenyl group-containing organosiloxane complex becomes activated on contact with moisture (humidity) and / or oxygen in the air and acts as an aerobic platinum catalyst (hydrosilylation addition reaction catalyst). They have also found that a curable liquid silicone composition containing this aerobic platinum catalyst mixture becomes a curable liquid silicone rubber composition or curable liquid silicone gel composition which has long-term storage stability as a one-part composition and which exhibits good deep curing properties when cured without heating, and have thus completed the present invention. The present invention cures a liquid silicone composition into silicone rubber or silicone gel by a curing (crosslinking) reaction system that applies a hydrosilylation addition reaction with an aerobic platinum catalyst mixture, and what is particularly noteworthy is that, by containing the platinum catalyst mixture of the present invention, the curable liquid silicone composition has "single-liquid storage stability in a sealed container" at refrigerated to room temperature (temperature range of -5 to 38°C), and also has the following characteristics: "When in contact with air, the platinum catalyst function is activated, the addition reaction progresses, and the composition cures not only on the surface in contact with air, but also in deeper areas" under unheated, open conditions (i.e., when in contact with moisture (humidity) and / or oxygen in the air at room temperature (23°C±15°C)).

[0008] Accordingly, the present invention provides the following platinum catalyst mixture: of A method of preparation is provided. [ 1 ] A method for preparing a platinum catalyst mixture, comprising mixing a platinum-alkenyl group-containing organosiloxane complex with an organosilicon compound having at least one hydrogen atom (SiH group) bonded to a silicon atom in the molecule in such a ratio 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 an oxygen-free atmosphere, to obtain a reaction mixture. [2] The platinum catalyst mixture according to [1], wherein the platinum-alkenyl group-containing organosiloxane complex is a complex of platinum, platinum chloride, chloroplatinic acid or a chloroplatinate salt with a vinyl group-containing siloxane. Method for preparing . [3] The platinum catalyst mixture according to [2], wherein the vinyl group-containing siloxane is 1,3-divinyl-1,1,3,3-tetramethyldisiloxane. Method for preparing . [4] The platinum catalyst mixture according to any one of [1] to [3], wherein the organosilicon compound having at least one hydrogen atom bonded to a silicon atom is an organohydrogensilane or an organohydrogensiloxane oligomer. Method for preparing . [5] The organosilicon compound having at least one hydrogen atom bonded to a silicon atom is one or more selected from trialkoxy(hydrogen)silane, alkyldialkoxy(hydrogen)silane, dialkylalkoxy(hydrogen)silane, 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 [1] to [ 3

[0023] The platinum catalyst mixture according to any one of the preceding claims. Method for preparing . [6] The organosilicon compound having at least one hydrogen atom bonded to a silicon atom is an organohydrogensiloxane oligomer having at least two hydrogen atoms (SiH groups) bonded to adjacent silicon atoms via oxygen atoms forming a siloxane bond (Si-O-Si) in the molecule.[1]~[ 3

[0023] The platinum catalyst mixture according to any one of the preceding claims. Method for preparing . [ 7 ] When the organosilicon compound having at least one hydrogen atom bonded to a silicon atom is an organohydrogensiloxane oligomer having at least two hydrogen atoms (SiH groups) in the molecule, each of which is bonded to adjacent silicon atoms via an oxygen atom forming a siloxane bond (Si-O-Si), the method further comprises a step of mixing the reaction mixture obtained by mixing in the above oxygen-free atmosphere while contacting it with moisture and / or oxygen. 1 ] ~[3] 2. A method for preparing a platinum catalyst mixture according to claim 1. Effect of the Invention

[0009] The platinum catalyst mixture of the present invention is activated as a hydrosilylation addition reaction catalyst by contacting with moisture (humidity) and / or oxygen in the air. The curable liquid silicone composition of the present invention containing the platinum catalyst mixture has sufficient "long-term one-liquid storage stability in a sealed container" for storing and transporting materials under refrigeration to room temperature, and when the material is used, it is possible for the aerobic platinum catalyst mixture contained in the composition to be activated, the hydrosilylation addition reaction to proceed, and the material to be rapidly cured not only on the surface exposed to air but also in the depths, under non-heated and open conditions (i.e., by contacting with moisture (humidity) and / or oxygen in the air at room temperature). The curable liquid silicone composition of the present invention (curable liquid silicone rubber composition and curable liquid silicone gel composition) can contribute to energy conservation and the production of various parts and products in accordance with the SDGs. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be described in detail below. [Platinum catalyst mixture] The platinum catalyst mixture of the present invention is an aerobic catalyst consisting of a reaction mixture of a platinum-alkenyl group-containing organosiloxane complex and an organosilicon compound having at least one SiH group in the molecule in an amount such that the number of hydrogen atoms bonded to silicon atoms (SiH groups) is in molar excess (molar ratio of more 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 an oxygen-free or low-moisture sealed state where contact with moisture (humidity) and oxygen is blocked, but the catalyst is activated as a hydrosilylation addition reaction catalyst by contact with moisture (humidity) and / or oxygen in the atmosphere. In addition, a sealed state (or under sealing) refers to a state where 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 realizes the sealed state. In addition, the "atmosphere" here is premised on an oxygen concentration of 21 vol% and a relative humidity of 5 to 100% RH (particularly 10 to 100% RH). An oxygen-free sealed state refers to an oxygen concentration of 0.1 vol% or less (particularly 0 to 0.05 vol%), and a low moisture content refers to a relative humidity of 3% RH or less (particularly 0 to 1% RH).

[0011] In the platinum catalyst mixture of the present invention, the platinum-alkenyl group-containing organosiloxane complex is preferably a complex of platinum, platinum chloride, chloroplatinic acid or chloroplatinate with a vinyl group-containing siloxane (for example, an organodisiloxane compound having two alkenyl groups in the molecule, such as 1,3-divinyl-1,1,3,3-tetramethyldisiloxane). 2 PtCl 6 In the case of a complex of platinic acid with 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.

[0012] 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 (content concentration) in the solution is preferably 0.05 to 5 mass %.

[0013] In the platinum catalyst mixture of the present invention, as the organosilicon compound having at least one hydrogen atom (SiH group) bonded to a silicon atom, an organohydrogensilane, an organohydrogensiloxane oligomer, etc. having at least one SiH group in the molecule (for example, 1 to 10, preferably 1 to 5) can be suitably used, but from the viewpoint of handling and safety, an organohydrogensiloxane oligomer is more preferable. The molecular structure of this organohydrogensiloxane oligomer may be linear or cyclic, and the number of silicon atoms in one molecule is preferably 2 to 40, more preferably 2 to 10, and even more preferably 2 to 5.

[0014] Examples of the organohydrogensilane and organohydrogensiloxane oligomer used in the present invention include trialkoxy(hydrogen)silane, alkyldialkoxy(hydrogen)silane, dialkylalkoxy(hydrogen)silane, 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. One or more compounds selected from these exemplary compounds may be used.

[0015] The platinum catalyst mixture of the present invention is a reaction mixture in which the alkenyl groups in the platinum-alkenyl group-containing organosiloxane complex react in an oxygen-free atmosphere with the SiH groups derived from the organosilicon compound added in an excess molar amount relative to the alkenyl groups (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 the alkenyl groups) during preparation of the mixture, resulting in all of the alkenyl groups being converted to alkylene groups by a hydrosilylation addition reaction (the alkenyl groups have essentially disappeared) and with excess SiH groups derived from the organosilicon compound remaining in the mixture.

[0016] It is also worth noting that in the platinum catalyst mixture of the present invention, the organosilicon compound having at least one hydrogen atom bonded to a silicon atom is an organohydrogensiloxane oligomer having in the molecule 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 forming a siloxane bond (Si-O-Si) (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-pentamethylcyclopentasiloxane, etc.), In the case where the organohydrogensiloxane oligomer having at least two adjacent SiH groups and the platinum-alkenyl group-containing organosiloxane complex are mixed uniformly in an oxygen-free atmosphere, the resulting reaction mixture is then contacted with moisture and / or oxygen by means of mixing in the air or the like. Alternatively, the reaction mixture is preferably obtained by mixing the organohydrogensiloxane oligomer having at least two adjacent SiH groups and the platinum-alkenyl group-containing organosiloxane complex in a state in contact with moisture and / or oxygen in a blending ratio such that the SiH groups in the organohydrogensiloxane oligomer having at least two adjacent SiH groups are in molar excess relative to the alkenyl groups in the platinum-alkenyl group-containing organosiloxane complex. As a result, a curable liquid silicone composition that contains this mixture as a hydrosilylation addition reaction catalyst can be made to have even better long-term one-part storage stability under sealed conditions without losing its curability when contacted with moisture (humidity) and / or oxygen in the air (see, for example, Examples 17, 21, and 22 below).

[0017] The method for preparing the platinum catalyst mixture of the present invention is characterized by mixing the above-mentioned platinum-alkenyl group-containing organosiloxane complex with an organosilicon compound having in the molecule at least one hydrogen atom bonded to a silicon atom (SiH group) in a compounding ratio 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 an oxygen-free atmosphere (for example, in an oxygen-free, sealed environment with low moisture content that is isolated from contact with moisture (humidity) and oxygen), to obtain a reaction mixture.

[0018] Here, the blending ratio in which the SiH groups of the organosilicon compound are in excess of moles relative to the alkenyl groups in the platinum-alkenyl group-containing organosiloxane complex 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 exceed 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.

[0019] 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) in the molecule. For example, it is preferable to use a glass reactor such as a glass flask or a stainless steel reactor.

[0020] The atmosphere during mixing is preferably oxygen-free, and is preferably an inert gas atmosphere such as nitrogen or reduced pressure (vacuum). There is no need to heat the mixture, and room temperature (23°C ± 15°C, the same applies below) may be used. The mixing time (i.e., reaction time) may be any time that allows the platinum-alkenyl group-containing organosiloxane complex and the organosilicon compound to be mixed uniformly, and is preferably, for example, 0.5 to 100 hours, particularly 1 to 24 hours.

[0021] In the method for preparing the platinum catalyst mixture of the present invention, when the organosilicon compound having at least one hydrogen atom bonded to a silicon atom in the platinum catalyst mixture of the present invention is an organohydrogensiloxane oligomer having at least two hydrogen atoms in the molecule bonded to adjacent silicon atoms via ether oxygen atoms forming a siloxane bond (Si-O-Si) (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-pentamethylcyclopentasiloxane, etc.), it is preferable to further include a step of mixing the reaction mixture obtained by mixing in the oxygen-free atmosphere while contacting it with moisture and / or oxygen. In this step, the reaction mixture is brought into contact with moisture and / or oxygen by means of mixing in the atmosphere, and for example, the mixing time in the atmosphere is preferably 0.5 to 100 hours, particularly preferably 1 to 12 hours. Thereafter, the platinum catalyst mixture is placed in a sealed container.

[0022] Further, another method for preparing a platinum catalyst mixture of the present invention is a method for preparing a platinum catalyst mixture by mixing a platinum-alkenyl group-containing organosiloxane complex with an organosilicon compound having at least one hydrogen atom (SiH group) bonded to a silicon atom in the molecule to obtain a reaction mixture, in which the organosilicon compound having at least one hydrogen atom bonded to a silicon atom in the molecule has hydrogen atoms bonded to adjacent silicon atoms via oxygen atoms forming a siloxane bond (Si-O-Si). The organohydrogensiloxane oligomer has at least two (adjacent SiH groups) in the molecule, and is characterized by mixing a platinum-alkenyl group-containing organosiloxane complex with an organosilicon compound having at least one hydrogen atom (SiH group) bonded to a silicon atom in the molecule in a blending ratio such that the SiH group of the organosilicon compound is in excess molar amount relative to the alkenyl group in the platinum-alkenyl group-containing organosiloxane complex, in a state of contact with moisture and / or oxygen. This preparation method brings the above components into contact with moisture and / or oxygen by means such as mixing in the atmosphere, and the mixing time in the atmosphere is preferably 0.5 to 100 hours, particularly 1 to 12 hours. Thereafter, the platinum catalyst mixture is stored in a sealed container.

[0023] As a result, a curable liquid silicone composition that contains this mixture as a hydrosilylation addition reaction catalyst can achieve even greater long-term one-part storage stability under sealed conditions without losing its curability when contacted with moisture (humidity) and / or oxygen in the air.

[0024] The platinum catalyst mixture of the present invention obtained as described above has low catalytic activity as a hydrosilylation addition reaction catalyst when it is kept in a sealed container that is protected from contact with oxygen and has a low moisture content, but when it comes into contact with moisture (humidity) and / or oxygen in the air, it becomes highly catalytically active. Thus, for example, when the platinum catalyst mixture of the present invention is added as a curing catalyst to a hydrosilylation addition reaction curing type curable liquid silicone composition, and the curable liquid silicone composition is stored in a sealed container that is protected from contact with oxygen and has a low moisture content, the composition will be able to exhibit sufficiently long-term one-part storage stability at refrigerated to room temperature. However, when the sealed container is opened and the composition is brought into contact with moisture (humidity) and / or oxygen from the atmosphere, the platinum catalyst mixture in the composition is activated at room temperature, achieving a state of high catalytic activity, and in the curable liquid silicone composition, the crosslinking (curing) reaction via the hydrosilylation addition reaction proceeds rapidly even without heating, and the curable liquid silicone composition will rapidly cure not only on the surface in contact with air but also in deeper portions, converting the curable liquid silicone composition into a rubber or gel.

[0025] [Curable liquid silicone composition] The curable liquid silicone composition of the present invention (curable liquid silicone rubber composition or curable liquid silicone gel composition) refers to a composition containing the below-described components (A) to (C) and, if necessary, other components.

[0026] [(A) Alkenyl-containing diorganopolysiloxane] The alkenyl-containing diorganopolysiloxane of component (A) is a linear or branched diorganopolysiloxane having at least one, and preferably two or more, alkenyl groups per molecule, and acts as the main agent (base polymer) of the curable liquid silicone composition of the present invention (hereinafter also referred to as the composition of the present invention). Typically, the main chain portion is basically composed of repeating diorganosiloxane units, and is generally a linear diorganopolysiloxane in which both molecular chain terminals are blocked with triorganosiloxy groups, but this may also be a branched one that contains a branched structure as part of the siloxane structure that makes up the molecular chain.

[0027] The alkenyl-containing diorganopolysiloxane of component (A) contains at least one alkenyl group (usually 1 to 50), preferably 1 to 20, more preferably 1 to 10, and even more preferably 1 or 2 alkenyl groups per molecule. Examples of the alkenyl group include vinyl, allyl, propenyl, isopropenyl, butenyl, hexenyl, and cyclohexenyl groups, which usually have about 2 to 8 carbon atoms. The alkenyl group may be bonded to a silicon atom at the molecular chain terminal or to a silicon atom at a non-terminal (in the middle of the molecular chain), and it is preferable that the alkenyl group contains an alkenyl group bonded to a silicon atom at at least (both) terminals of the molecular chain. In this case, the alkenyl group may be present only at both terminals of the molecular chain, or may be present at both terminals of the molecular chain and non-terminals (in the middle of the molecular chain).

[0028] An example of such an alkenyl-containing diorganopolysiloxane is a linear diorganopolysiloxane represented by the following general formula (1). [ka] (In the formula, R 1 are independently an unsubstituted or substituted monovalent hydrocarbon group that does not contain an aliphatic unsaturated bond. X is an alkenyl group, and at least one is contained in the molecule. n is an integer of 0 or more, m is an integer of 0 or more, and a is an integer of 0 to 3 independently for each silicon atom to which it is bonded.

[0029] In the formula, R 1Examples 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 of such groups include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, and dodecyl groups; cycloalkyl groups such as cyclopentyl, cyclohexyl, and cycloheptyl groups; aryl groups such as phenyl, tolyl, xylyl, naphthyl, and biphenylyl groups; aralkyl groups such as benzyl, phenylethyl, phenylpropyl, and methylbenzyl groups; 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 a cyano group, for example, a chloromethyl group, a 2-bromoethyl group, a 3-chloropropyl group, a 3,3,3-trifluoropropyl group, a chlorophenyl group, a fluorophenyl group, a cyanoethyl group, or a 3,3,4,4,5,5,6,6,6-nonafluorohexyl group, and the like, are included, and preferred are unsubstituted or substituted alkyl groups having 1 to 3 carbon atoms such as a methyl group, an ethyl group, a propyl group, a chloromethyl group, a bromoethyl group, a 3,3,3-trifluoropropyl group, or a cyanoethyl group, and unsubstituted or substituted phenyl groups such as a phenyl group, a chlorophenyl group, or a fluorophenyl group. R 1 As the alkyl group, a methyl group and a phenyl group are preferable.

[0030] 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. Among these, lower alkenyl groups such as a vinyl group and an allyl group are preferred.

[0031] In the formula, n is an integer of 0 or more, preferably an integer of 10 to 2,000, more preferably an integer of 50 to 1,200, and m is an integer of 0 or more, preferably an integer of 0 to 40, more preferably an integer of 0 to 20. In addition, n and m are preferably integers that satisfy 10≦n+m≦2,000, more preferably 50≦n+m≦1,200 and 0≦m / (n+m)≦0.2. In this case, each unit in the parentheses enclosed by n and m may be randomly arranged. 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.

[0032] Furthermore, such alkenyl-containing diorganopolysiloxanes preferably have a viscosity at 23° C. of about 10 to 1,000,000 mPa·s, and more preferably about 100 to 500,000 mPa·s.

[0033] In the present invention, the number of repetitions of 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) in gel permeation chromatography (GPC) analysis using toluene as a developing solvent, etc. The 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.).

[0034] The alkenyl-containing diorganopolysiloxane of component (A) may be used alone or in combination of two or more. In order not to impair the function of the platinum catalyst mixture of component (C) described below, it is advisable to reduce the oxygen and water content in the alkenyl-containing diorganopolysiloxane of component (A) before blending it into the composition, for example, by replacing it with an inert gas such as nitrogen gas, heating or reducing the pressure, or a combination of these.

[0035] [(B) Organohydrogenpolysiloxane] (B) The organohydrogenpolysiloxane has a linear, cyclic, branched or three-dimensional network structure and has at least two 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.

[0036] (B) The organohydrogenpolysiloxane acts as a crosslinking agent (curing agent) for the composition of the present invention, contains at least two (usually 2 to 200, preferably about 3 to 100) hydrogen atoms bonded to silicon atoms (i.e., SiH groups) in one molecule, and may have any of a linear, branched, cyclic, or three-dimensional network structure (resin structure).

[0037] 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 that does not contain 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.)

[0038] In the formula, R 2 Examples of the unsubstituted or substituted monovalent hydrocarbon group that does not contain an aliphatic unsaturated bond are the same as those exemplified as R 1 in the general formula (1), and include, for example, those having 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 7 carbon atoms, and particularly preferably lower alkyl groups having 1 to 3 carbon atoms such as a methyl group, a phenyl group, and a 3,3,3-trifluoropropyl group.

[0039] The component (B) is preferably a compound that is liquid at room temperature and has 2 to 300 silicon atoms in one molecule, particularly 2 to 150, and even more particularly about 2 to 100 silicon atoms. The hydrogen atoms bonded to the silicon atoms may be located at either the terminals of the molecular chain or in the middle of the molecular chain (non-terminal), or may be located at both.

[0040] 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 capped with trimethylsiloxy groups at both molecular chain terminals; dimethylsiloxane-methylhydrogensiloxane copolymers capped with trimethylsiloxy groups at both molecular chain terminals; diphenylsiloxane-methylhydrogensiloxane copolymers capped with trimethylsiloxy groups at both molecular chain terminals; and methylphenylsiloxane-methylhydrogensiloxane capped with trimethylsiloxy groups at both molecular chain terminals. copolymer, dimethylsiloxane-diphenylsiloxane-methylhydrogensiloxane copolymer capped at both molecular chain ends with trimethylsiloxy groups, dimethylpolysiloxane capped at both molecular chain ends with dimethylhydrogensiloxy groups, methylhydrogenpolysiloxane capped at both molecular chain ends with dimethylhydrogensiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymer capped at both molecular chain ends with dimethylhydrogensiloxy groups, diphenylsiloxane-methylhydrogensiloxane copolymer capped at both molecular chain ends with dimethylhydrogensiloxy groups, methylphenylsiloxane-methylhydrogensiloxane copolymer capped at both molecular chain ends with dimethylhydrogensiloxy groups, dimethylsiloxane-diphenylsiloxane-methylhydrogensiloxane copolymer capped at both molecular chain ends with dimethylhydrogensiloxy groups, dimethylhydrogensiloxy unit and SiO 4 / 2Examples of such compounds include silicone resins having a three-dimensional network structure consisting of units and optionally containing 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 the organosilicon compound in component (C) described below may be the same as that in component (B).

[0041] The organohydrogenpolysiloxane used in the composition of the present invention can be obtained by a known method, for example, a compound represented by the following general formula: 2 SiHCl 2 and R 2 2 SiHCl (wherein, R 2 is the same as above.) or by co-hydrolyzing the chlorosilane with a compound represented by the following general formula: R 2 3 SiCl and R 2 2 SiCl 2 (In the formula, R 2 is the same as above.) and at least one chlorosilane selected from the group consisting of chlorosilanes ...

[0042] From the viewpoint of providing a good silicone rubber and gel upon curing, the amount of the organohydrogenpolysiloxane of component (B) blended is desirably such that 0.5 to 4 moles, and preferably 0.8 to 2.5 moles, of hydrogen atoms bonded to silicon atoms in the organohydrogenpolysiloxane of component (B) (i.e., SiH groups) per mole of alkenyl groups in the alkenyl-group-containing diorganopolysiloxane of component (A).

[0043] The organohydrogenpolysiloxane of component (B) may be used alone or in combination of two or more. In order not to impair the function of the aerobic platinum catalyst mixture of component (C) described later, it is preferable to reduce the oxygen and water content in the organohydrogenpolysiloxane of component (B) before blending it into the composition, for example, by replacing it with an inert gas such as nitrogen gas, heating or reducing the pressure, or a combination of these.

[0044] [(C) Platinum catalyst mixture] The curable liquid silicone composition of the present invention is characterized by the incorporation of the above-mentioned platinum catalyst mixture of the present invention as a platinum catalyst in component (C) for promoting the hydrosilylation addition reaction between the alkenyl groups in component (A) and the hydrogen atoms bonded to silicon atoms (SiH groups) in component (B).

[0045] In the curable liquid silicone composition of the present invention, the amount of the platinum catalyst mixture in the component (C) may be a so-called catalytic amount, but it is an amount that is 0.1 to 1,000 ppm, preferably 0.5 to 200 ppm, calculated as the mass of platinum atoms contained in the component (C) relative to the total mass of the components (A) and (B). If the amount of the component (C) is less than the above range, the material will not be cured sufficiently due to the influence of catalyst inhibition factors when the material is used, and if it is more than the above range, the storage stability will be poor. Note that, since the amount of the component (C) is a so-called catalytic amount, the excess molar amount of SiH groups remaining in the component (C) is negligibly small, and does not substantially affect the molar ratio of the SiH groups in the component (B) to the alkenyl groups in the component (A) described above.

[0046] [Other ingredients] In addition to the above components (A) to (C), various optional components such as those listed below can be added to the curable liquid silicone composition of the present invention, as necessary, provided the object of the present invention is not impaired.

[0047] [(D) Dehydrating agent] The curable liquid silicone composition of the present invention can further contain, as an optional component, a dehydrating agent (D) to remove water from the composition, if necessary. By incorporating a dehydrating agent (D), it becomes possible to obtain better storage stability.

[0048] As described above, the platinum catalyst mixture of component (C), which is the core technology of the present invention, has the property that its catalytic activity is suppressed to a low level in an oxygen-free, low-moisture environment where contact with moisture (humidity) and oxygen is blocked, and its catalytic function is activated by moisture and / or oxygen from the outside air (atmosphere) (aerobic reaction type). For this reason, it has been confirmed that the one-part storage stability of the curable liquid silicone composition is improved by reducing the amount of moisture in each component and the amount of moisture in the mixed composition, and it is useful in ensuring the storage stability of the one-part composition to introduce a mechanism that consumes (dehydrates) moisture from the components and trace amounts of moisture that enter from outside the container within the composition when stored in a sealed container.

[0049] The compound that enables this dehydration may be either an inorganic compound or an organic compound, so long as it does not impair the functions of the above components (A), (B), and (C). However, depending on the compound that enables dehydration, foaming may occur due to the by-product compound produced by the dehydration reaction, and many compounds may also cause decomposition of the hydrogen siloxane in the composition or a decrease in the catalytic activity of the platinum catalyst mixture.

[0050] Therefore, as the dehydrating agent of component (D), silyl ketenes (including silyl ketene acetals), silyl enol esters, and α-silyl esters are suitable as they enable efficient dehydration within the system. These compounds have a structure in which the by-products produced during dehydration do not impair the functions of the above components (A), (B), and (C), and are soluble in the liquid silicone composition, making it possible to form 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, so they do not cause decomposition of hydrogen siloxanes or a decrease in the catalytic activity of the platinum catalyst mixture.

[0051] Examples of the silyl ketenes (containing silyl ketene acetals) include 1-methoxy-2-methyl-1-(trimethylsiloxy)propene, dimethyl ketene trimethylsilyl acetal, and tert-butoxy-1-(trimethylsiloxy)propene.

[0052] Examples of α-silyl esters include ethyl 2-(trimethoxysilyl)propionate (ECMS) and octyl 2-(methyldimethoxysilyl)propionate (OCMS-2).

[0053] The dehydrating agent (D) may be added to each component in advance, may be added during the preparation of the composition, or may be added after the composition has been prepared. The amount added is preferably 5% by mass or less, particularly preferably 2% by mass or less, of the total composition.

[0054] A catalyst may be added to promote the reaction between the component (D) and water. Examples of such catalysts include titanate esters (e.g., tetra(isopropyl)titanate (TPT), tetrabutyltitanate (TBT), tetra(2-ethylhexyl)titanate (TOT), etc.), titanium chelate compounds (e.g., titanium diisopropoxybis(ethylacetoacetate), titanium tetraacetylacetonate), and tin compounds (e.g., dibutyldimethoxytin, dibutyltin dilaurate). The amount of the catalyst added is preferably 2% by mass or less, particularly 1% by mass or less, of the entire composition.

[0055] [(E) Addition reaction regulator]

[0043] It is also useful to further incorporate an addition reaction inhibitor, component (E), as an optional component in the curable liquid silicone composition of the present invention, for the purpose of improving the storage stability of the one-part composition, in the same manner as the dehydrating agent, component (D), described above.

[0056] As described above, the platinum catalyst mixture of component (C), which is the core technology of the present invention, has the property that its catalytic function is activated by moisture. Therefore, a part of the platinum catalyst mixture of component (C) may be activated as an addition reaction catalyst due to moisture in each component, moisture mixed in during the process of preparing the composition or the process of filling the container, and moisture entering from outside the sealed container. This activated catalyst may significantly reduce the one-part storage stability of the composition, but such a decrease in one-part storage stability can be suppressed by supplementarily adding the addition reaction inhibitor of component (E).

[0057] Examples of the addition reaction inhibitor of component (E) include acetylene alcohols such as 1-ethynylcyclohexanol and 3-methyltridec-1-yn-3-ol (EMDC), and silane and siloxane modified products of acetylene alcohols such as dimethylbis(1,1-dimethyl-2-propynyloxy)silane (PLR-22) and 3-(trimethylsilyloxy)-3-methyl-1-butyne (PLR-31), tri(isopropyl)phosphite, tris(di-tert-butylphenyl)phosphite, triphenylphosphite, tris(2-ethyl) ... Examples of suitable compounds include compounds selected from the group consisting of phosphorous acid compounds (particularly phosphite esters) such as tris(isopropyl)phosphite and tris(di-tert-butylphenyl)phosphite, ethylenediamines such as tetramethylethylenediamine, benzotriazole, 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-liquid storage stability under airtightness.

[0058] The amount of the addition reaction inhibitor (E) may be any amount that does not affect the curing properties of the composition of the present invention, depending on the performance of each addition reaction inhibitor, but in the case of a phosphorous compound such as a phosphorous ester, the amount may be a small amount, less than 1 mole, particularly about 0 to 0.75 moles, per mole of platinum atom contained in the composition. If the amount of the (E) component is too large, the platinum catalyst mixture (C) activated by moisture during use will be deactivated, and the curing properties when exposed to the atmosphere may decrease.

[0059] [(F) Inorganic filler] The curable liquid silicone composition of the present invention may further contain an inorganic filler (F) as an optional component, as necessary, for the purposes of adjusting the viscosity when uncured, improving the strength of the cured silicone rubber or cured silicone gel product after curing, and adjusting the appearance color. Examples of the inorganic filler (F) that may be added include reinforcing inorganic fillers such as fumed silica and fumed titanium dioxide, and non-reinforcing inorganic fillers such as calcium silicate, titanium dioxide, ferric oxide, and carbon black.

[0060] The amount of the inorganic filler in the (F) component is usually 200 parts by mass or less per 100 parts by mass of the (A) component, and when the (F) component is used, the amount is preferably 0.1 to 200 parts by mass, more preferably 0.5 to 50 parts by mass, per 100 parts by mass of the (A) component. If the amount of the inorganic filler used is less than 0.1 part by mass, the effect of adding the filler may not be obtained, and if it exceeds 200 parts by mass, it may be difficult to mix the filler uniformly into a mixture.

[0061] [(G) Adhesion promoter] When the application requires high self-adhesion, the curable liquid silicone composition of the present invention may further contain, as an optional component if necessary, a hydrolyzable organosilane compound (so-called carbon functional silane or silane coupling agent) and / or a partial hydrolyzed condensate thereof as an adhesion promoter for component (G) in order to improve the adhesion of the cured product to various substrates. The optional component may be an alkoxysilane containing a monovalent hydrocarbon group having a functional group containing a heteroatom selected from oxygen, nitrogen and sulfur atoms (epoxy group, (meth)acryloxy group, mercapto group, etc.).

[0062] When the adhesion promoter (G) is added, the amount is preferably 0.1 to 20 parts by mass, and more preferably about 0.2 to 10 parts by mass, per 100 parts by mass of the (A) component. If the amount of the adhesion promoter is less than 0.1 part by mass, the desired adhesiveness will not be fully achieved, and if it is more than 20 parts by mass, the material viscosity may be significantly reduced.

[0063] [(H) Plasticizer] The curable liquid silicone composition of the present invention may further contain, as an optional component, so-called non-functional silicone oils such as dimethylpolysiloxane capped at both molecular terminals with trimethylsilyl groups (dimethylsilicone oil), dimethylsiloxane-diphenylsiloxane copolymer capped at both molecular terminals with trimethylsilyl groups, and dimethylsiloxane-methylphenylsiloxane copolymer capped at both molecular terminals with trimethylsilyl groups (methylphenylsilicone oil), which do not contain functional groups in the molecule that participate in hydrosilylation addition reactions, such as alkenyl groups or hydrosilyl groups (SiH groups), in order to adjust the viscosity of the composition and the hardness of the cured product, as necessary.

[0064] When the plasticizer (H) is added, the amount is preferably 0.1 to 50 parts by mass, and more preferably about 0.5 to 20 parts by mass, per 100 parts by mass of the (A) component. If the amount of non-functional silicone oil (plasticizer) is less than 0.1 part by mass, the plasticization intended for its addition may not be achieved, whereas if it is more than 50 parts by mass, the plasticizer may separate and bleed out from the cured material.

[0065] In addition to the above-mentioned optional components of (D) dehydrating agent, (E) addition reaction regulator, (F) inorganic filler, (G) adhesion imparting agent, and (H) plasticizer, the curable liquid silicone composition of the present invention may further contain, as necessary, other optional components such as pigment pastes that use as binders the same components as the non-functional silicone oils used as the plasticizers described above, or reinforcing silicone resins.

[0066] The curable liquid silicone composition of the present invention can achieve better one-part storage stability by using a highly airtight container capable of blocking or reducing the intrusion of moisture (humidity) and / or oxygen from the atmosphere, storing the composition in the airtight container, and distributing and selling the composition. Furthermore, when the airtight container is opened and the curable liquid silicone composition of the present invention is exposed to the atmosphere and exposed to moisture (humidity) and / or oxygen from the atmosphere at room temperature, not only the surface exposed to air but also the deeper parts are rapidly cured to give a silicone rubber cured product or a silicone gel cured product.

[0067] (Method of curing the curable liquid silicone composition) The method for curing the curable liquid silicone composition of the present invention is characterized by comprising the step of exposing the above-mentioned curable liquid silicone composition of the present invention to the atmosphere at room temperature to cure it.

[0068] When the curable liquid silicone composition of the present invention is exposed to the atmosphere, the platinum catalyst mixture of component (C) in the composition comes into contact with moisture (humidity) and / or oxygen in the atmosphere, activating the catalytic function of the platinum catalyst mixture, and curing of the curable liquid silicone composition begins even at room temperature. At this time, not only the surface of the composition exposed to air but also the deeper part quickly cures, and a silicone rubber cured product or a silicone gel cured product can be obtained.

[0069] 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 in-vehicle parts, aircraft, home appliances, etc. EXAMPLES

[0070] 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 a value measured by a rotational viscometer at 23°C, and the degree of polymerization is a number-average degree of polymerization calculated as polystyrene in GPC analysis using toluene as a developing solvent. Me represents a methyl group, and Vi represents a vinyl group. "Room temperature" means 23°C. The oxygen concentration in the "atmosphere" is 21 vol%, and the relative humidity is 50% RH.

[0071] [Preparation Examples 1-9] Preparation of platinum catalyst mixture Aerobic platinum catalyst mixtures (C-1) to (C-9) were prepared as follows. At this time, a toluene solution of (Ca) chloroplatinic acid-divinyltetramethyldisiloxane complex (platinum atom content: 0.5% by mass) was used as the platinum-alkenyl group-containing organosiloxane complex. The following organohydrogenpolysiloxanes (Cb-1) to (Cb-4) were used as organosilicon compounds having at least one hydrogen atom bonded to a silicon atom. Note that (Cb-2) and (Cb-4) are organohydrogenpolysiloxanes each having adjacent SiH groups in the molecule. (Cb-1) 1,1,1,3,3-Pentamethyldisiloxane (Cb-2) 1,1,3,3-Tetramethyldisiloxane (vicinal SiH group type) (Cb-3) 1,1,1,3,5,5,5-heptamethyltrisiloxane (Cb-4) 1,3,5,7-Tetramethylcyclotetrasiloxane (vicinal SiH group type) (Preparation instructions) At room temperature (23°C) in a nitrogen atmosphere, the platinum-alkenyl group-containing organosiloxane complex (Ca) and the organohydrogenpolysiloxanes (Cb-1) to (Cb-4) were uniformly mixed and reacted in a 25 g glass bottle for 12 hours in the proportions shown in Table 1 below, and then the bottle was sealed to prepare aerobic platinum catalyst mixtures (C-1), (C-3), (C-5), and (C-7). Furthermore, for each of the mixtures in 25 g glass bottles prepared in the same manner as above (C-1), (C-3), (C-5), and (C-7), the lids of the glass bottles were opened in the atmosphere at room temperature (23°C) and the mixtures were mixed uniformly while being in contact with the atmosphere for a further 2 hours, and then the bottles were sealed to prepare aerobic platinum catalyst mixtures (C-2), (C-4), (C-6), and (C-8). In addition, two components with the same composition as (C-3) (platinum-alkenyl group-containing organosiloxane complex (Ca) and organohydrogenpolysiloxane (Cb-2)) were mixed in a glass bottle for 12 hours in air, and the glass bottle was sealed while still containing air to prepare an aerobic platinum catalyst mixture (C-9).

[0072] [Table 1]

[0073] [Examples 1 to 22, 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 Tables 2 and 3 below in a glass bottle under a nitrogen atmosphere at room temperature (23°C) and sealing the bottle. The molar ratio of SiH groups in component (B) to vinyl groups in component (A) was 2.2 in the formulation in Table 2 and 1.2 in the formulation in Table 3. The ingredients were added in the following order while mixing: (A) alkenyl-containing diorganopolysiloxane, (B) organohydrogenpolysiloxane, (D) dehydrating agent, (E) addition reaction inhibitor, and (C) aerobic platinum catalyst mixture. If any ingredient was not added, that ingredient was skipped and the addition of the subsequent ingredients was continued. In order to prepare the composition with good reproducibility, (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 process and container filling process of the composition were carried out under a nitrogen atmosphere.

[0074] The details of each component are as follows: (A) Alkenyl group-containing diorganopolysiloxane: (A-1) a vinyl group-containing linear diorganopolysiloxane having a viscosity of 5,000 mPa s at 23°C, as represented by the following average formula: Vi(Me) 2 SiO-(Si(Me) 2 O) 300 -Si(Me) 2 Vi (A-2) A vinyl-containing linear diorganopolysiloxane having a viscosity of 800 mPa s at 23°C, as represented by the following average formula: [Vi(Me) 2 SiO] 1.2 -(Si(Me) 2 O) 100 -[Si(Me) 3 ] 0.8

[0075] (B) Organohydrogenpolysiloxane: (B-1) A linear organohydrogenpolysiloxane represented by the following average formula: (Me) 3 SiO-(Si(Me) 2 O) 63 -(Si(H)(Me)O) 20 -Si(Me) 3

[0076] (C) Aerobic platinum catalyst mixture: The aerobic platinum catalyst mixtures (C-1) to (C-9) prepared in Preparation Examples 1 to 9 were used. In addition, as a comparative component (C'), a toluene solution (platinum atom content 0.5% by mass) of (Ca) chloroplatinic acid-divinyltetramethyldisiloxane complex, which was an intermediate raw material used in the preparation of the platinum catalyst mixture, was used.

[0077] (D) Dehydrating agent: (D-1) Ethyl 2-(trimethylsilyl)propionate (ECMS) (α-silyl esters) (D-2) 1-methoxy-2-methyl-1-(trimethylsiloxy)propene (silyl ketene acetal) represented by the following formula [ka] (D') If necessary, tetra(isopropyl)titanate (TPT) was added as a catalyst for promoting the reaction of component (D) with moisture.

[0078] (E) Addition reaction regulator: (E-1) Tri(isopropyl)phosphite (0.10% by mass solution in toluene) (E-2) Tris(di-tert-butylphenyl)phosphite represented by the following formula (0.31% by mass solution in toluene) [ka]

[0079] The prepared curable liquid silicone compositions were evaluated for their one-part storage stability under closed conditions, their curability after storage in the open air at room temperature (room temperature curability), and the hardness of the cured product, as described below. The one-liquid storage stability is measured by filling a glass bottle with the curable liquid silicone composition under a nitrogen atmosphere, sealing the bottle, and then leaving the bottle in air / room temperature to observe the thickening and gelling behavior of the curable liquid silicone composition.At this time, the thickening and gelling behavior of the curable liquid silicone composition is measured by observing the degree to which the composition in the glass bottle flows following the tilt of the glass bottle (fluidity), and the state in which the fluidity becomes worse than that immediately after sealing is judged to be thickened or gelled.In addition, at this time, the glass bottle in which the curable liquid silicone composition is sealed is left in air / room temperature and then observed for 5 minutes, and then observed every day to confirm the time (minutes, days) until the curable liquid silicone composition thickens or gels. The room temperature curing property was evaluated by taking the curable liquid silicone composition stored in a sealed glass bottle for one day as described above, taking it out into another container (depth 4 mm) under a nitrogen atmosphere, exposing it to an air / room temperature environment, and measuring the time it took to cure into a rubber or gel state as the curing time. At this time, a needle was pierced into the container to check the state of cure deep inside. The hardness of the cured product was measured by casting the curable liquid silicone rubber composition immediately after preparation as obtained above into a glass petri dish and exposing it to an air / room temperature environment for 24 hours. For the rubber-like cured product, the hardness (type A durometer) specified in JIS K 6249 was measured, and for the gel-like cured product, the penetration (1 / 4 cone consistency according to JIS K 2220) specified in JIS K 6249 was measured. The above results are shown in Tables 2 and 3.

[0080] [Table 2]

[0081] [Table 3]

[0082] As a result of the above, it was confirmed that the curable liquid silicone composition of the present invention has excellent one-part storage stability in a sealed container, and that when exposed to air in an unheated, open environment (room temperature in the atmosphere), the platinum catalyst mixture is activated, the addition reaction proceeds, and the composition hardens into a rubber-like or gel-like form.

Claims

1. A method for preparing a platinum catalyst mixture, comprising mixing a platinum-alkenyl group-containing organosiloxane complex with an organosilicon compound having in the molecule at least one hydrogen atom bonded to a silicon atom (SiH group) in an oxygen-free atmosphere in such a compounding ratio 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, to obtain a reaction mixture.

2. 2. The method for preparing a platinum catalyst mixture according to claim 1, wherein the platinum-alkenyl group-containing organosiloxane complex is a complex of platinum, platinum chloride, chloroplatinic acid or a chloroplatinate salt with a vinyl group-containing siloxane.

3. 3. The method for preparing a platinum catalyst mixture according to claim 2, wherein the vinyl-containing siloxane is 1,3-divinyl-1,1,3,3-tetramethyldisiloxane.

4. 4. The method for preparing a platinum catalyst mixture according to claim 1, wherein the organosilicon compound having at least one hydrogen atom bonded to a silicon atom is an organohydrogensilane or an organohydrogensiloxane oligomer.

5. The method for preparing a platinum catalyst mixture according to any one of claims 1 to 3, wherein the organosilicon compound having at least one hydrogen atom bonded to a silicon atom is one or more selected from 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.

6. 4. The method for preparing a platinum catalyst mixture according to any one of claims 1 to 3, wherein the organosilicon compound having at least one hydrogen atom bonded to a silicon atom is an organohydrogensiloxane oligomer having in the molecule at least two hydrogen atoms (SiH groups) bonded to adjacent silicon atoms via oxygen atoms forming a siloxane bond (Si-O-Si).

7. 4. The method for preparing a platinum catalyst mixture according to any one of claims 1 to 3, wherein the organosilicon compound having at least one hydrogen atom bonded to a silicon atom is an organohydrogensiloxane oligomer having in its molecule at least two hydrogen atoms (SiH groups) bonded to adjacent silicon atoms via oxygen atoms forming a siloxane bond (Si-O-Si), further comprising a step of mixing the reaction mixture obtained by mixing in an oxygen-free atmosphere while contacting it with moisture and / or oxygen.

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