Platinum-phosphite complex-containing hydrosilylation catalyst, method for producing the same, method for inhibiting crystallization of platinum-phosphite complex-containing hydrosilylation catalyst, and curable organopolysiloxane composition and article

Abstract

A platinum-phosphite ester complex-containing hydrosilylation catalyst has good storage stability and comprises: a platinum-phosphite ester complex composed of platinum and a phosphite ester compound having a specific structure; and a liquid alkenyl group-containing siloxane compound containing an organopolysiloxane compound having two or more adjacent alkenyl groups, the catalyst being free of a hydrocarbon-based organic solvent and being liquid at 23°C. By using the catalyst, a one-component (one-part) curable organopolysiloxane composition free of a hydrocarbon-based organic solvent can be easily obtained, and the resulting one-component curable organopolysiloxane composition has stable characteristics and physical properties even when exposed to ambient temperature for a long period of time.

Description

[Technical Field]

[0001] The present invention relates to a platinum-phosphite complex-containing hydrosilylation catalyst, a method for producing the hydrosilylation catalyst, a method for inhibiting crystallization of the platinum-phosphite complex-containing hydrosilylation catalyst, a curable organopolysiloxane composition containing the hydrosilylation catalyst, and an article having a cured product thereof. [Background technology]

[0002] An addition-curable silicone composition (an addition-curable organopolysiloxane composition; the term "addition-curable silicone composition" used herein refers to a composition in which the cured product obtained by curing the composition can be either a rubber-cured product (an elastomer elastic material) such as silicone rubber, or a gel-cured product (a low-stress non-elastic material that does not exhibit an effective rubber hardness value) such as silicone gel, with no restrictions on the hardness after curing) contains an organopolysiloxane having alkenyl groups such as vinyl groups bonded to silicon atoms as the main component (base polymer), an organohydrogenpolysiloxane having hydrogen atoms bonded to silicon atoms (i.e., SiH groups) as the curing agent (crosslinking agent), and a platinum-based catalyst as the curing catalyst, and is prepared as a millable (raw rubber-like) or liquid addition-reaction-curable organopolysiloxane composition that obtains a cured product by an addition reaction of the hydrogen atoms bonded to the silicon atoms to the alkenyl groups. The addition-curable silicone compositions are heated to cure them, producing silicone cured products such as silicone rubber and silicone gel. These products have excellent heat resistance, weather resistance, oil resistance, cold resistance, and electrical insulation properties, and are therefore used in a wide range of applications, including electrical and electronic components, optical components, building materials, and automotive sealing materials.

[0003] As mentioned above, addition-curable silicone compositions produce a cured silicone product by heating. In the case of one-component silicone compositions, exposure to high temperatures during storage can lead to problems such as changes in properties, such as thickening and gelation, and changes in the physical properties of the cured silicone product obtained after curing. To avoid these problems, methods have been adopted, such as creating a mixed silicone composition by dividing the components into two or more components and mixing them immediately before use, or transporting one-component silicone compositions refrigerated or frozen. The former method raises concerns about changes in the physical properties of the resulting cured silicone product due to blending or mixing, requiring highly advanced blending and mixing techniques, making it unsuitable for everyone. Furthermore, the latter method requires refrigeration or freezing between storage and use, resulting in significant transportation and storage costs and making it commercially unsuitable. Against this backdrop, there has been a growing demand in recent years for one-component addition-curable silicone compositions whose properties and performance remain unchanged even after long-term storage at room temperature (here, 23°C ± 15°C).

[0004] Against this background, Japanese Patent No. 2849027 (Patent Document 1) proposes a method of adding an amine compound with an ethylenediamine skeleton. However, in this publication, the addition of an amine compound can cause problems such as corrosion of electronic substrates and a deterioration in electrical properties. Furthermore, Japanese Patent No. 4530147 (Patent Document 2) proposes a method of using a catalyst obtained by heat-aging a specific phosphite ester compound together with a platinum catalyst. However, in this publication, the activity of the catalyst obtained by heat-aging is unstable, and an organic peroxide is used in combination. Therefore, there are handling restrictions and prolonged exposure to room temperature can cause thickening and gelation, making low-temperature conditions essential for storage and transportation to ensure performance stability.

[0005] Additionally, overseas, European Patent Application Publication No. 2050768A1 and U.S. Patent No. 6706840 (Patent Documents 3 and 4) propose methods using platinum-phosphite complexes. However, even in the above two publications, prolonged exposure to room temperature causes thickening and gelation, so low-temperature conditions are essential for storage and transportation to maintain performance stability.

[0006] Furthermore, U.S. Patent No. 4,256,616 (Patent Document 5) proposes a method using a platinum-phosphite complex and a tin salt. However, since this publication uses a tin compound, there are concerns about its toxicity to the human body, and since prolonged exposure to room temperature causes thickening and gelation, low-temperature conditions are essential for storage and transportation to maintain performance stability.

[0007] Furthermore, U.S. Patent No. 4,329,275 (Patent Document 6) proposes a method using a platinum catalyst, a phosphorus compound, and an organic peroxide that does not contain a hydroperoxide group. Even with the composition proposed in the above publication, thickening and gelation occur when exposed to room temperature for a long period of time, so low-temperature conditions are essential for storage and transportation to ensure performance stability.

[0008] Recently, German Patent Application Publication No. 60316102T2 (Patent Document 7) describes a one-component organopolysiloxane gel composition made from a platinum catalyst, a phosphite triester, and an organic peroxide. The phosphite triester is described as tris(2,4-di-tert-butylphenyl) phosphite, and a method is proposed in which the amount of organic peroxide present is at least 2 equivalents based on the phosphite triester. Furthermore, Japanese Patent Publication No. 2018-503709 (Patent Document 8) proposes a method using tris(2,4-di-tert-butylphenyl) phosphite. However, these methods require the use of environmentally harmful hydrocarbon organic solvents such as xylene to dissolve tris(2,4-di-tert-butylphenyl) phosphite, resulting in the problem of hydrocarbon organic solvents being contained in the resulting silicone composition.

[0009] In recent years, WO 2021 / 014970 and JP 2021-042323 A (Patent Documents 9 and 10) have proposed methods for improving storage stability using certain specific phosphite ester compounds. While these proposals do indeed dramatically improve storage stability, they have the drawbacks of not being able to obtain a sufficiently cured silicone product unless exposed to high temperatures of around 150°C, and of having poor storage stability in air due to the high hydrolysis properties of the phosphite ester compound. Therefore, there has been a demand for a platinum-phosphite complex-containing hydrosilylation catalyst that is liquid at 23°C and does not contain hydrocarbon organic solvents. If such a catalyst could be obtained, it would be possible to obtain a one-component addition-curable silicone composition that does not contain hydrocarbon organic solvents, which have a high environmental impact, and has stable properties and physical characteristics. Therefore, there has been a growing demand for a platinum-phosphite complex-containing hydrosilylation catalyst that is liquid at 23°C and does not contain hydrocarbon organic solvents. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Patent No. 2849027 [Patent Document 2] Patent No. 4530147 [Patent Document 3] European Patent Application Publication No. 2050768A1 [Patent Document 4] U.S. Patent No. 6,706,840 [Patent Document 5] U.S. Patent No. 4,256,616 [Patent Document 6] U.S. Patent No. 4,329,275 [Patent Document 7] German Patent Application Publication No. 60316102T2 [Patent Document 8] Special Publication No. 2018-503709 [Patent Document 9] International Publication No. 2021 / 014970 [Patent Document 10] Japanese Patent Publication No. 2021-042323 Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been made to solve these problems, and its object is to provide a platinum-phosphite complex-containing hydrosilylation catalyst that is liquid at 23°C and has good storage stability without containing hydrocarbon organic solvents, which have a large environmental impact, and a method for producing the same; a method for suppressing crystallization of a platinum-phosphite complex-containing hydrosilylation catalyst; a hydrocarbon organic solvent-free curable organopolysiloxane composition that contains the catalyst and whose properties and physical properties are stable even when exposed to room temperature (23°C±15°C) for long periods of time; and an article comprising the cured product thereof. [Means for solving the problem]

[0012] As a result of extensive research conducted by the present inventors to achieve the above object, it has been found that a compound represented by the following general formula (1) [ka] (In the formula, R 1 are independently a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 3 carbon atoms. A solution is prepared by dissolving a phosphite ester compound represented by the formula: in a hydrocarbon organic solvent having a boiling point of 80°C or less, and platinum chloride, Sour a platinum catalyst containing no hydrocarbon organic solvent, selected from one or more platinum-alkenyl group-containing siloxane complexes formed from chloroplatinic acid salts and alkenyl group-containing siloxanes, is added, dispersed, and dissolved to prepare a solution containing a platinum-phosphite complex composed of platinum and the phosphite compound represented by the general formula (1) above, and ...2) below [ka] (In the formula, R 2 represents an alkenyl group having 2 to 10 carbon atoms, and R 3 is a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, and n is an integer of 2 to 200. and dispersing and dissolving the resulting solution containing an association of at least a portion of the platinum-phosphite complex and the siloxane compound represented by general formula (2), and then removing the hydrocarbon organic solvent having a boiling point of 80°C or less from the solution. This has been found to yield a platinum-phosphite complex-containing hydrosilylation catalyst that is stable in liquid form even during long-term storage at 23°C, even without the hydrocarbon organic solvent. The present inventors also discovered that by using the platinum-phosphite complex-containing hydrosilylation catalyst obtained above, it is possible to obtain a one-component (one-liquid) curable organopolysiloxane composition that does not contain a hydrocarbon organic solvent, and that the resulting one-component curable organopolysiloxane composition exhibits stable properties and physical characteristics even when exposed to room temperature for long periods of time, leading to the completion of the present invention.

[0013] Accordingly, the present invention provides the following platinum-phosphite complex-containing hydrosilylation catalyst, a method for producing the hydrosilylation catalyst, a method for inhibiting crystallization of the platinum-phosphite complex-containing hydrosilylation catalyst, a curable organopolysiloxane composition containing the hydrosilylation catalyst, and an article having a cured product thereof. [1] Platinum and the following general formula (1) [ka] (In the formula, R 1 are independently a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 3 carbon atoms. and a platinum-phosphite ester complex composed of a phosphite ester compound represented by the following general formula (2): [ka] (In the formula, R 2 represents an alkenyl group having 2 to 10 carbon atoms, and R 3 is a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, and n is an integer of 2 to 200. The platinum-phosphite ester complex-containing hydrosilylation catalyst is a liquid at 23°C and does not contain any hydrocarbon organic solvents. [2] The platinum-phosphite complex-containing hydrosilylation catalyst according to [1], wherein the organopolysiloxane compound having a unit represented by general formula (2) is a cyclic organopolysiloxane compound. [3] The platinum-phosphite complex-containing hydrosilylation catalyst according to [1] or [2], wherein at least a portion of the platinum-phosphite complex is associated with an organopolysiloxane compound having a unit represented by general formula (2). [4] The platinum-phosphite complex-containing hydrosilylation catalyst according to [3], wherein 0.01 to 100 mol % of the platinum-phosphite complex is associated with an organopolysiloxane compound having a unit represented by general formula (2). [5] The platinum-phosphite complex-containing hydrosilylation catalyst according to any one of [1] to [4], wherein the alkenyl group-containing siloxane compound further contains 1,3-divinyl-1,1,3,3-tetramethyldisiloxane and / or 1,5-divinyl-1,1,3,3,5,5-hexamethyltrisiloxane. [6] A curable organopolysiloxane composition containing the platinum-phosphite complex-containing hydrosilylation catalyst according to any one of [1] to [5]. [7] The curable organopolysiloxane composition according to [6], which does not contain a hydrocarbon organic solvent. [8] An article comprising a cured product of the curable organopolysiloxane composition according to [6] or [7]. [9] A method for producing a platinum-phosphite complex-containing hydrosilylation catalyst, comprising the following steps (a) to (d): (a) preparing a solution of a phosphite ester compound represented by the following general formula (1) in a hydrocarbon organic solvent having a boiling point of 80°C or less; [ka] (In the formula, R 1 are independently a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 3 carbon atoms. (b) adding platinum chloride, platinum chloride to the solution; Sour a step of adding, dispersing, and dissolving a platinum catalyst containing no hydrocarbon organic solvent, selected from one or more platinum-alkenyl group-containing siloxane complexes formed from chloroplatinic acid salts and alkenyl group-containing siloxanes, to prepare a solution containing a platinum-phosphite complex composed of platinum and the phosphite compound represented by the general formula (1); (c) adding an organopolysiloxane compound having a unit represented by the following general formula (2) to the solution obtained in step (b), and dispersing and dissolving the compound to prepare a solution containing an association of at least a portion of the platinum-phosphite ester complex and the organopolysiloxane compound having a unit represented by the following general formula (2); [ka] (In the formula, R 2 represents an alkenyl group having 2 to 10 carbon atoms, and R 3 is a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, and n is an integer of 2 to 200. and, (d) A step of removing the hydrocarbon organic solvent from the solution obtained in step (c).

[10] The method for producing a platinum-phosphite complex-containing hydrosilylation catalyst according to [9], wherein 0.01 to 500 moles of an organopolysiloxane compound having a unit represented by general formula (2) are added per mole of platinum atoms in the platinum-phosphite complex.

[11] A method for inhibiting crystallization of a platinum-phosphite complex-containing hydrosilylation catalyst, comprising the following steps (a) to (d): (a) preparing a solution of a phosphite ester compound represented by the following general formula (1) in a hydrocarbon organic solvent having a boiling point of 80°C or less; [ka] (In the formula, R 1 are independently a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 3 carbon atoms. (b) adding platinum chloride, platinum chloride to the solution; Sour a step of adding, dispersing, and dissolving a platinum catalyst containing no hydrocarbon organic solvent, selected from one or more platinum-alkenyl group-containing siloxane complexes formed from chloroplatinic acid salts and alkenyl group-containing siloxanes, to prepare a solution containing a platinum-phosphite complex composed of platinum and the phosphite compound represented by the general formula (1); (c) adding an organopolysiloxane compound having a unit represented by the following general formula (2) to the solution obtained in step (b), and dispersing and dissolving the compound to prepare a solution containing an association of at least a portion of the platinum-phosphite ester complex and the organopolysiloxane compound having a unit represented by the following general formula (2); [ka] (In the formula, R 2 represents an alkenyl group having 2 to 10 carbon atoms, and R 3 is a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, and n is an integer of 2 to 200. and, (d) A step of removing the hydrocarbon organic solvent from the solution obtained in step (c).

[12] The method for inhibiting crystallization of a platinum-phosphite complex-containing hydrosilylation catalyst according to

[11] , wherein 0.01 to 500 moles of an organopolysiloxane compound having a unit represented by general formula (2) are added per mole of platinum atoms in the platinum-phosphite complex. [Effects of the Invention]

[0014] The platinum-phosphite ester complex-containing hydrosilylation catalyst of the present invention remains a stable liquid even during long-term storage at 23°C, even without the addition of hydrocarbon organic solvents, and therefore exhibits excellent stability of its properties. Furthermore, when the catalyst is incorporated into a one-component (one-liquid) curable organopolysiloxane composition, it can be easily dispersed uniformly, resulting in a curable organopolysiloxane composition that is free of hydrocarbon organic solvents. The resulting one-component curable organopolysiloxane composition that is free of hydrocarbon organic solvents provides a composition with stable properties and physical characteristics even when exposed to room temperature (23°C ± 15°C) for extended periods of time. Furthermore, the absence of hydrocarbon organic solvents allows for the production of extremely safe cured products. DETAILED DESCRIPTION OF THE INVENTION

[0015] [Platinum-phosphite complex-containing hydrosilylation catalyst] The platinum-phosphite ester complex-containing hydrosilylation catalyst of the present invention comprises platinum and a compound represented by the following general formula (1): [ka] (In the formula, R 1 are independently a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 3 carbon atoms. and a platinum-phosphite ester complex composed of a phosphite ester compound represented by the following general formula (2): [ka] (In the formula, R 2 represents an alkenyl group having 2 to 10 carbon atoms, and R 3 is a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, and n is an integer of 2 to 200. The platinum-phosphite complex-containing hydrosilylation catalyst is a liquid at 23°C and does not contain any hydrocarbon organic solvents. The catalyst comprises a liquid alkenyl group-containing siloxane compound containing an organopolysiloxane compound having a unit represented by the formula: In the present invention, being a liquid at 23° C. means that the platinum-phosphite complex in the platinum-phosphite complex-containing hydrosilylation catalyst is not crystallized.

[0016] In the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention, at least a portion of the platinum-phosphite complex is preferably associated with an organopolysiloxane compound having units represented by general formula (2), and preferably 0.01 to 100 mol %, and particularly 0.02 to 100 mol %, of the platinum-phosphite complex is associated with an organopolysiloxane compound having units represented by general formula (2). If the amount is less than 0.01 mol %, the platinum-phosphite complex in the platinum-phosphite complex-containing hydrosilylation catalyst may crystallize and become cloudy during long-term storage. It is believed that when a platinum-phosphite ester complex and an organopolysiloxane compound having units represented by general formula (2) are dispersed or dissolved in the organopolysiloxane compound in a free (liquid) state and brought into contact with the organopolysiloxane compound, associations are quantitatively and easily formed in accordance with the blending ratio, and the presence of these associations is believed to suppress crystallization of the platinum-phosphite ester complex (see Examples 1, 2, and 3 and Comparative Example 2 described below). In contrast, alkenyl group-containing siloxane compounds other than organopolysiloxane compounds having units represented by general formula (2) are thought not to effectively form associations even when in contact with platinum-phosphite complexes (see Comparative Examples 1 and 2 described below).

[0017] <Platinum-phosphite complex> The platinum-phosphite complex contained in the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention is composed of platinum and a phosphite compound represented by the general formula (1) described below.

[0018] [Phosphite ester compounds] In the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention, the phosphite compound represented by the following general formula (1) contained as the platinum-phosphite complex is an essential component, and by forming a complex with platinum (platinum-phosphite complex), it is possible to significantly improve the storage stability of the properties and physical properties of the curable organopolysiloxane composition containing the catalyst of the present invention. [ka] (In the formula, R 1 are independently a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 3 carbon atoms.

[0019] In the above formula (1), R 1 are independently a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 3 carbon atoms, preferably a monovalent aliphatic hydrocarbon group having 1 or 2 carbon atoms, more preferably a monovalent aliphatic hydrocarbon group having 1 carbon atom, i.e., a methyl group.

[0020] Specific examples of the phosphite ester compound represented by the above formula (1) include tris(2,4-dimethylphenyl)phosphite, tris(2,4-di-tert-butylphenyl)phosphite, tris(2,4-bis(3-ethylpentan-3-yl)phenyl)phosphite, and tris(2,4-bis(4-propylheptan-4-yl)phenyl)phosphite. 1 and phosphite compounds having the same number of carbon atoms, and R such as tris(4-(tert-butyl)-2-methylphenyl)phosphite, tris(4-(tert-butyl)-2-ethylphenyl)phosphite, tris(2-(tert-butyl)-4-(3-ethylpentan-3-yl)phenyl)phosphite, and tris(2-(tert-butyl)-4-(3-methylhexan-3-yl)phenyl)phosphite. 1 Among these, it is particularly preferable to use tris(2,4-di-tert-butylphenyl)phosphite, which is easily available and has excellent storage stability.

[0021] In the platinum-phosphite complex, the phosphite compound represented by the general formula (1) is preferably present in an amount of more than 0.6 mol but not more than 1.9 mol, and more preferably 0.8 to 1.5 mol, per mol of platinum atom. If the amount is 0.6 mol or less, the storage stability of the resulting curable organopolysiloxane composition containing the platinum-phosphite complex-containing hydrosilylation catalyst may be poor or the composition may gel. If the amount is more than 1.9 mol, the platinum-phosphite complex in the resulting platinum-phosphite complex-containing hydrosilylation catalyst may crystallize at room temperature (23°C ± 15°C, the same applies hereinafter), potentially making it unable to retain liquid.

[0022] <Alkenyl group-containing siloxane compound> The alkenyl group-containing siloxane compound contained in the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention is liquid at 23°C and contains an organopolysiloxane compound having a unit represented by general formula (2) described below.

[0023] [Organopolysiloxane compounds] The organopolysiloxane compound having a unit represented by the following general formula (2), which is contained in the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention, is an essential component that associates with at least a portion of the platinum-phosphite complex described above, thereby preventing the platinum-phosphite complex in the platinum-phosphite complex-containing hydrosilylation catalyst from crystallizing at room temperature. [ka] (In the formula, R 2 represents an alkenyl group having 2 to 10 carbon atoms, and R 3 is a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, and n is an integer of 2 to 200.

[0024] In the organopolysiloxane compound having a bifunctional siloxane unit represented by the general formula (2), n is 2 or more (i.e., [(R2 )(R 3 )SiO 2 / 2 ]), and therefore, the organopolysiloxane has in its molecule at least two alkenyl groups such as vinyl groups (hereinafter, sometimes referred to as adjacent vinyl groups or adjacent alkenyl groups in the present invention) bonded to silicon atoms (hereinafter, sometimes referred to as adjacent silicon atoms in the present invention) at non-terminal positions of the molecular chain (in the middle of the molecular chain) present in adjacent bifunctional siloxane units via ether oxygen atoms that form siloxane bonds (Si-O-Si). It is preferable that the organopolysiloxane compound having units represented by the general formula (2) be composed solely of units represented by the formula (2) other than the molecular chain terminals (i.e., triorganosiloxy units or diorganohydroxysiloxy units).

[0025] In the above formula (2), R 2 is an alkenyl group having 2 to 10 carbon atoms, preferably an alkenyl group having 2 to 4 carbon atoms (such as a vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, or isobutenyl group), and more preferably an alkenyl group having 2 carbon atoms, i.e., a vinyl group. In addition, in the above formula (2), R 3 is a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, preferably a monovalent saturated aliphatic hydrocarbon group (alkyl group) having 1 to 4 carbon atoms, and more preferably a monovalent saturated aliphatic hydrocarbon group having 1 carbon atom, i.e., a methyl group. In the above formula (2), n is an integer of 2 to 200, preferably an integer of 3 to 100, more preferably an integer of 4 to 40, and even more preferably an integer of 4 to 10.

[0026] The terminals of the organopolysiloxane compound having the bifunctional siloxane unit represented by the general formula (2) are not particularly limited, but when the organopolysiloxane compound is linear or branched, the molecular chain terminals may be silanol group-containing siloxy groups (diorganohydroxysiloxy groups) or triorganosiloxy groups such as trimethylsiloxy groups or dimethylvinylsiloxy groups. Furthermore, when the organopolysiloxane compound is a cyclic organopolysiloxane compound (organocyclopolysiloxane compound), there are no molecular chain terminals. The organopolysiloxane compound having two or more adjacent alkenyl groups each having a unit represented by the general formula (2) is a component that prevents crystallization of the platinum-phosphite ester complex by associating with the platinum-phosphite ester complex. Therefore, when the compound is dispersed and mixed with the platinum-phosphite ester complex and brought into contact with the platinum-phosphite ester complex, it must be in a liquid state in which the molecules are individually free.

[0027] Specific examples of the organopolysiloxane compound include organoalkenylcyclopolysiloxanes (here, the organo group refers to an alkyl group) such as 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane, vicinal alkenyl group-containing cyclic polysiloxanes such as organoalkenylsiloxane-diorganosiloxane cyclic copolymers (ditto), and vicinal alkenyl group-containing siloxane polymers (vicinal alkenyl group-containing linear methylvinylpolysiloxanes) obtained by linear ring-opening polymerization of 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane via an equilibration reaction. As mentioned above, there are no limitations on the terminals of the vicinal alkenyl group-containing siloxane polymer (vicinal alkenyl group-containing linear methylvinylpolysiloxane) linearly ring-opening polymerized by an equilibration reaction, but polymers containing trimethylsiloxy groups, silanol group-containing siloxy groups (dimethylhydroxysiloxy groups), or dimethylvinylsiloxy groups are preferably used. Among these, the organopolysiloxane compound having a unit represented by the above general formula (2) is preferably a cyclic organopolysiloxane compound (organocyclopolysiloxane compound) that can reduce the viscosity of the platinum-phosphite complex-containing hydrosilylation catalyst itself.

[0028] The amount of organopolysiloxane compound having units represented by general formula (2) is preferably 0.01 to 500 moles, more preferably 0.02 to 200 moles, even more preferably 0.03 to 100 moles, and most preferably 0.05 to 50 moles, per mole of platinum atom in the platinum-phosphite complex. If the amount is less than 0.01 mole, the platinum-phosphite complex in the platinum-phosphite complex-containing hydrosilylation catalyst may crystallize at room temperature, making it unable to retain liquid, or may cause problems such as poor dispersibility and reduced blending workability when the catalyst is blended into a curable organopolysiloxane composition. Furthermore, if the amount exceeds 500 moles, the effective platinum amount of the platinum-phosphite complex-containing hydrosilylation catalyst itself will decrease, and therefore, when preparing a curable organopolysiloxane composition incorporating this catalyst, a significantly larger amount will be required. This will increase the amount of organopolysiloxane compound having units represented by general formula (2) added, increasing the likelihood of problems such as reduced mechanical properties and reduced curability.

[0029] [Other alkenyl group-containing siloxane compounds] In addition to organopolysiloxane compounds having units represented by the aforementioned general formula (2) (vicinal alkenyl group-containing organopolysiloxane compounds), the alkenyl group-containing siloxane compounds can also include alkenyl group-containing disiloxane compounds such as 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 1,3-diallyl-1,1,3,3-tetramethyldisiloxane, 1,3-divinyl-1,3-dimethyl-1,3-diphenyldisiloxane, and 1,3-divinyl-1,1,3,3-tetraphenyldisiloxane, and trisiloxane compounds containing terminal alkenyl groups such as 1,5-divinyl-1,1,3,3,5,5-hexamethyltrisiloxane. Examples of such alkenyl group-containing disiloxane compounds and trisiloxane compounds containing a terminal alkenyl group include the alkenyl group-containing siloxane compounds contained as ligands for the platinum atom in the platinum catalyst used as an intermediate raw material in preparing the platinum-phosphite complex in the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention. In the case of the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention, the platinum catalyst (for example, a platinum-alkenyl group-containing siloxane complex such as a Karstedt complex) which is an intermediate raw material described below is used in the form of a catalyst solution such as a silicone solution. The platinum catalyst is preferably a linear diorganopolysiloxane having no alkenyl groups along the molecular chain, such as a linear dimethylpolysiloxane having vinyldimethylsiloxy groups capped at both molecular chain ends, and particularly a linear diorganopolysiloxane having no alkenyl groups along the molecular chain, and particularly a linear diorganopolysiloxane having a degree of polymerization of 14 or more. Terminally alkenyl-containing siloxy-blocked linear diorganopolysiloxanes (terminally alkenyl-containing silicone oils) are not counted as alkenyl-containing siloxane compounds other than organopolysiloxane compounds having units represented by the general formula (2) described above (i.e., they are excluded from the constituent components of the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention). However, because they do not have an adverse effect on the present invention, they may be included in the curable organopolysiloxane composition as a silicone solution of the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention.

[0030] The content of the alkenyl group-containing siloxane compound other than the organopolysiloxane compound having the unit represented by general formula (2) is preferably 0 to 99.5 mass %, more preferably 0.5 to 98 mass %, of the alkenyl group-containing siloxane compound. If the content of this compound is too high, the concentration of the organopolysiloxane compound having the unit represented by general formula (2) in the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention will decrease, and the formation of an association between the platinum-phosphite complex and the organopolysiloxane compound having the unit represented by general formula (2) will not be effectively promoted, and the platinum-phosphite complex in the platinum-phosphite complex-containing hydrosilylation catalyst may crystallize and become cloudy during long-term storage.

[0031] [Method for producing a platinum-phosphite complex-containing hydrosilylation catalyst] The platinum-phosphite complex-containing hydrosilylation catalyst described above can be produced stably by carrying out the following four steps. (a) preparing a solution of the phosphite compound represented by the general formula (1) in a hydrocarbon organic solvent having a boiling point of 80°C or less; (b) adding platinum chloride, platinum chloride to the solution; Sour a step of adding, dispersing, and dissolving a platinum catalyst containing no hydrocarbon organic solvent, selected from one or more platinum-alkenyl group-containing siloxane complexes formed from chloroplatinic acid salts and alkenyl group-containing siloxanes, to prepare a solution containing a platinum-phosphite complex composed of platinum and the phosphite compound represented by the general formula (1); (c) adding an organopolysiloxane compound having a unit represented by the general formula (2) to the solution obtained in the step (b), and dispersing and dissolving the compound to prepare a solution containing an association of at least a portion of the platinum-phosphite ester complex and the organopolysiloxane compound having a unit represented by the general formula (2); and (d) A step of removing the hydrocarbon organic solvent from the solution obtained in step (c).

[0032] Each step will be described in detail below. First step: (a) The first step is to prepare a solution in which a phosphite compound represented by the following general formula (1) is dissolved in a hydrocarbon organic solvent having a boiling point of 80° C. or less. [ka] (In the formula, R 1 are independently a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 3 carbon atoms.

[0033] This is an essential step for quickly forming a complex with platinum, which is added in the subsequent step, since many of the phosphite ester compounds represented by general formula (1) are solid at room temperature.

[0034] [Phosphite ester compounds] The phosphite ester compound represented by general formula (1) is as described above, and among them, it is particularly preferable to use tris(2,4-di-tert-butylphenyl)phosphite, which is easily available and has excellent storage stability.

[0035] [Hydrocarbon organic solvents with a boiling point of 80°C or less] The phosphite ester compound represented by the general formula (1) is often solid at room temperature. Therefore, it is necessary to dissolve the phosphite ester compound in a hydrocarbon-based organic solvent having a boiling point of 80°C or less to prepare a solution, and then, in the second step, mix the solution with a platinum catalyst (described below) to form a platinum-phosphite ester complex. In the present invention, the term "hydrocarbon-based organic solvent" refers to an organic compound having a hydrocarbon skeleton that is liquid at room temperature (23°C ± 15°C) and may contain heteroatoms (oxygen, nitrogen, and sulfur atoms) in the molecule. This term excludes organosilicon compounds such as organosilane compounds and organopolysiloxane compounds. The boiling point referred to here is the boiling point at atmospheric pressure.

[0036] The hydrocarbon organic solvent having a boiling point of 80°C or less may be linear or branched. Specific examples of hydrocarbon organic solvents having a boiling point of 80°C or less include n-pentane (boiling point: 36°C), n-hexane (boiling point: 68°C), 2-methylbutane (boiling point: 30°C), 2,2-dimethylbutane (boiling point: 50°C), 2,3-dimethylbutane (boiling point: 58°C), 2-methylpentane (boiling point: 62°C), and 3-methylpentane (boiling point: 63°C). Among these, n-hexane (boiling point: 68°C) is particularly suitable because it is relatively easy to handle for industrial use and is easily removed in the subsequent removal process.

[0037] The boiling point of 80°C or less is required because, in the step of removing the hydrocarbon organic solvent from the prepared platinum-phosphite complex-containing hydrosilylation catalyst, it is preferred to distill the hydrocarbon organic solvent off under reduced pressure, and in this case, the hydrocarbon organic solvent can be removed even if the vacuum distillation temperature is 40°C or lower, making it possible to obtain a stable platinum-phosphite complex-containing hydrosilylation catalyst. In the case of a hydrocarbon organic solvent with a boiling point exceeding 80°C, the used hydrocarbon organic solvent cannot be completely removed unless the vacuum distillation temperature exceeds 40°C. This may result in the hydrocarbon organic solvent remaining in the platinum-phosphite complex-containing hydrosilylation catalyst or in the platinum-phosphite complex-containing hydrosilylation catalyst being decomposed by the temperature in the solvent removal step, resulting in the precipitation of crystals.

[0038] The amount of the hydrocarbon organic solvent having a boiling point of 80°C or less to be used is not particularly limited, but is preferably 100 to 10,000 parts by mass, and more preferably 1,000 to 5,000 parts by mass, per 100 parts by mass of the phosphite ester compound represented by general formula (1).

[0039] The temperature at which the phosphite ester compound represented by general formula (1) is dissolved in the hydrocarbon organic solvent is preferably 40°C or lower, more preferably in the range of 0 to 35°C. Dissolving at temperatures above 40°C makes the phosphite ester compound represented by general formula (1) more susceptible to hydrolysis by the water contained in the hydrocarbon organic solvent, which makes the phosphite ester compound represented by general formula (1) more likely to convert to a phosphate ester compound, resulting in a decrease in the stability of the resulting platinum-phosphite complex-containing hydrosilylation catalyst. The dissolution time is not particularly limited, and should be approximately 10 minutes to 24 hours, as long as the phosphite ester compound represented by general formula (1) is dissolved in the hydrocarbon organic solvent. It is preferable to select a container capable of blocking oxygen during dissolution.

[0040] Second step: (b) The second step is to add platinum chloride, platinum chloride to the solution obtained in step (a). Sour is a process for preparing a solution containing a platinum-phosphite ester complex composed of platinum and the phosphite ester compound represented by the general formula (1) by adding, dispersing, and dissolving a platinum catalyst containing no hydrocarbon organic solvent, selected from one or more platinum-alkenyl group-containing siloxane complexes formed from chloroplatinate and alkenyl group-containing siloxanes such as vinyl group-containing siloxanes.

[0041] [Platinum catalyst] The platinum catalyst used as an intermediate raw material in the preparation of the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention is platinum chloride, platinum chloride, Souris a platinum catalyst containing no hydrocarbon organic solvent, selected from one or more platinum-alkenyl group-containing siloxane complexes formed from chloroplatinate and an alkenyl group-containing siloxane such as a vinyl group-containing siloxane; the platinum catalyst itself is usually a curing catalyst (hydrosilylation addition reaction catalyst) contained in an addition-curable silicone composition, which contributes to the hydrosilylation addition reaction between alkenyl groups in the base polymer (alkenyl group-containing organopolysiloxane) and SiH groups in the crosslinker (organohydrogenpolysiloxane).

[0042] In the present invention, the platinum catalyst is further dispersed and dissolved in a solution containing the phosphite compound represented by the general formula (1) described above, to obtain a platinum-phosphite complex-containing hydrosilylation catalyst, which contains a platinum-phosphite complex composed of platinum and the phosphite compound represented by the general formula (1). By using this catalyst as a curing catalyst for an addition-curable silicone composition (addition-curable organopolysiloxane composition), the properties and storage stability of the physical properties of the target curable organopolysiloxane composition can be significantly improved.

[0043] Among the platinum catalysts used as intermediate raw materials, examples of the alkenyl group-containing siloxanes in the platinum-alkenyl group-containing siloxane complexes include 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 1,3-diallyl-1,1,3,3-tetramethyldisiloxane, 1,3-divinyl-1,3-dimethyl-1,3-diphenyldisiloxane, 1,3-divinyl-1,1,3,3-tetraphenyldisiloxane, 1,5-divinyl-1,1,3,3,5,5-hexamethyltrisiloxane, 1,3,5-trimethyl-1,3,5-trivinylcyclotrisiloxane, and 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane. The structures of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 1,3,5-trimethyl-1,3,5-trivinylcyclotrisiloxane, and 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane are shown below. [ka]

[0044] Platinum chloride (PtCl4), chloroplatinic acid (H2PtCl6 )again is selected from one or more platinum-alkenyl group-containing siloxane complexes formed from chloroplatinic acid salt (H2PtCl6·6H2O) and alkenyl group-containing siloxanes such as vinyl group-containing siloxanes, and is a platinum catalyst that does not contain hydrocarbon organic solvents. Specific examples of the platinum-alkenyl group-containing siloxane complex include platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex (Karstedt complex), platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex (Karstedt complex), Examples of suitable platinum catalysts include allyl-1,1,3,3-tetramethyldisiloxane complex, platinum-1,3-divinyl-1,3-dimethyl-1,3-diphenyldisiloxane complex, platinum-1,3,5-trimethyl-1,3,5-trivinylcyclotrisiloxane complex, platinum-1,3-divinyl-1,1,3,3-tetraphenyldisiloxane complex, and platinum-1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane complex. The platinum-alkenyl group-containing siloxane complex is preferably at least one selected from these groups, and it is essential that it does not contain hydrocarbon organic solvents. Among the platinum catalysts listed above, platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex (Karstedt complex) is particularly preferred.

[0045] The platinum catalysts described here must be free of basic hydrocarbon organic solvents, such as aromatic organic solvents such as toluene and xylene, and alcoholic organic solvents such as ethanol, n-butanol, and 2-ethylhexyl alcohol (however, this does not include low-molecular-weight, vinyl-containing oligosiloxanes such as tetramethyldivinyldisiloxane, trimethyltrivinylcyclotrisiloxane, and tetramethyltetravinylcyclotetrasiloxane, as well as linear organopolysiloxanes (so-called silicone oils) such as linear dimethylpolysiloxanes terminally capped with dimethylvinylsiloxy groups, linear dimethylpolysiloxanes terminally capped with trimethylsiloxy groups, and linear methylphenylpolysiloxanes terminally capped with trimethylsiloxy groups). These solvents may have adverse effects on the human body, so they must not be contained.

[0046] This platinum chloride, platinum chloride Sour The hydrocarbon-based organic solvent-free platinum catalyst is preferably in the form of a silicone solution using an alkenyl-containing organopolysiloxane (typically a linear organopolysiloxane capped at both molecular terminals with vinyldiorganosiloxy groups, such as a linear dimethylpolysiloxane capped at both molecular terminals with dimethylvinylsiloxy groups, that does not have adjacent alkenyl groups in the molecule) as a diluent (solvent), which may be the same or different from the alkenyl-containing siloxane that forms the ligand of the platinum-alkenyl-containing siloxane complex. This silicone solution is typically prepared to have a platinum atom content of approximately 0.001 to 0.010 mol %. This is to improve the stability and handleability (workability) of the platinum-alkenyl-containing siloxane complex. The amount (mass concentration) of platinum contained in the silicone solution is about 0.2 to 2.0 mass %.

[0047] The optimum ratio of the platinum catalyst and phosphite compound to be added is more than 0.6 molecules and not more than 1.9 molecules of phosphite compound per platinum atom in the platinum catalyst, and more preferably 0.8 molecules or more and 1.5 molecules or less per platinum atom in the platinum catalyst. If the ratio of the phosphite compound to the platinum atom in the platinum catalyst is 0.6 molecules or less, the storage stability of the resulting curable organopolysiloxane composition containing the platinum-phosphite complex-containing hydrosilylation catalyst may be impaired, and there is a high risk of the curable organopolysiloxane composition gelling. On the other hand, if there are more than 1.9 molecules of phosphite compound per platinum atom in the platinum catalyst, even if the platinum-phosphite complex obtained in the second step is associated in the third step with an organopolysiloxane compound having a unit represented by the general formula (2) described above, there is a high risk that the platinum-phosphite complex in the resulting platinum-phosphite complex-containing hydrosilylation catalyst will crystallize and precipitate at room temperature, making it impossible to maintain the platinum-phosphite complex-containing hydrosilylation catalyst in a liquid state at 23°C, or causing problems such as poor dispersibility and reduced blending workability when the platinum-phosphite complex-containing hydrosilylation catalyst is blended into a curable organopolysiloxane composition.

[0048] In this step, the method for adding the platinum catalyst is not particularly limited, and the platinum catalyst may be added to the phosphite compound solution all at once, or may be added in portions, or may be added dropwise over a predetermined period of time.

[0049] In this step, the dispersion and dissolution of the platinum catalyst is preferably carried out at a temperature of 40° C. or lower, particularly 0 to 35° C., for 30 minutes or longer, particularly 30 minutes to 4 hours. As in the first step, it is preferable to select a container that can block oxygen for this step, and the container used in the first step can be used as is.

[0050] By dispersing and dissolving under the above conditions, a platinum-phosphite complex composed of platinum and the phosphite compound represented by the general formula (1) is formed.

[0051] Third step: (c) The third step is a step of adding an organopolysiloxane compound having a unit represented by the following general formula (2) (organopolysiloxane compound having two or more vicinal alkenyl groups) to the solution obtained in step (b), and dispersing and dissolving the mixture to prepare a solution containing an association product of at least a portion of the platinum-phosphite ester complex and an organopolysiloxane compound having a unit represented by the following general formula (2) (organopolysiloxane compound having two or more vicinal alkenyl groups): [ka] (In the formula, R 2 represents an alkenyl group having 2 to 10 carbon atoms, and R 3 is a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, and n is an integer of 2 to 200.

[0052] In the present invention, by associating at least a portion of a platinum-phosphite complex with an organopolysiloxane compound having units represented by the above general formula (2), a platinum-phosphite complex-containing hydrosilylation catalyst is obtained that is liquid at 23°C without containing a hydrocarbon organic solvent and has excellent dispersibility and property stability. Furthermore, when this platinum-phosphite complex-containing hydrosilylation catalyst is used as a curing catalyst in an addition-curable silicone composition (curable organopolysiloxane composition), a composition with stable properties and physical characteristics can be obtained even when exposed to room temperature for long periods of time, and it is also possible to obtain a composition that does not contain a hydrocarbon organic solvent.

[0053] The organopolysiloxane compound having units represented by general formula (2) (organopolysiloxane compound having two or more adjacent alkenyl groups) is as described above. Note that the organopolysiloxane compound having units represented by general formula (2) is a component that prevents crystallization of the platinum-phosphite ester complex by associating with the platinum-phosphite ester complex, and when dispersed and mixed with the platinum-phosphite ester complex and brought into contact with the platinum-phosphite ester complex, it is in a liquid state with individually free molecules, which is different from the alkenyl group-containing siloxanes such as vinyl group-containing siloxanes that serve as ligands complexed with the platinum atom in the platinum-alkenyl group-containing siloxane complex.

[0054] In the step (b) of preparing the platinum-phosphite complex, the alkenyl-group-containing siloxane, which serves as a ligand and which has formed a complex with the platinum atom in the platinum-alkenyl-group-containing siloxane complex, which is the intermediate raw material, dissociates (is liberated) from the platinum-phosphite complex. However, if this liberated alkenyl-group-containing siloxane is an alkenyl-group-containing siloxane other than an organopolysiloxane compound having a unit represented by general formula (2) (an organopolysiloxane compound having two or more adjacent alkenyl groups) (for example, 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, which is a ligand of the Karstedt complex), it is believed that the alkenyl-group-containing siloxane will not associate with the platinum-phosphite complex, as described above. On the other hand, when the liberated alkenyl group-containing siloxane corresponds to an organopolysiloxane compound having units represented by general formula (2) (organopolysiloxane compound having two or more vicinal alkenyl groups), it is thought that the liberated alkenyl group-containing siloxane can also form an association complex with the platinum-phosphite ester complex. However, from the viewpoint of more reliably forming an association complex between the platinum-phosphite ester complex and an organopolysiloxane compound having units represented by general formula (2) (organopolysiloxane compound having two or more vicinal alkenyl groups) (from the viewpoint of suppressing crystallization of the platinum-phosphite ester complex and more reliably improving storage stability), after preparing the platinum-phosphite ester complex, it is further mixed and contacted with an organopolysiloxane compound having units represented by general formula (2) (organopolysiloxane compound having two or more vicinal alkenyl groups) in step (c).

[0055] The amount of organopolysiloxane compound having units represented by general formula (2) used is preferably 0.01 to 500 moles, more preferably 0.02 to 200 moles, even more preferably 0.03 to 100 moles, and most preferably 0.05 to 50 moles, per mole of platinum atom in the platinum-phosphite complex (the platinum catalyst used in the second step). If the amount of organopolysiloxane compound having units represented by general formula (2) per mole of platinum atom in the platinum-phosphite complex is less than 0.01 mole, the amount of organopolysiloxane compound having units represented by general formula (2) associated per mole of platinum atom will be so small that it will be difficult to maintain liquid properties at 23°C, and crystals will precipitate. This can lead to problems such as poor dispersibility and reduced compounding workability when the catalyst is incorporated into a curable organopolysiloxane composition. Furthermore, if the amount of organopolysiloxane compound having units represented by general formula (2) exceeds 500 moles per mole of platinum atoms in the platinum-phosphite complex, the viscosity of the resulting platinum-phosphite complex-containing hydrosilylation catalyst will be significantly affected, which may result in problems such as reduced workability when blending the catalyst.

[0056] In this step, the method for adding the organopolysiloxane compound having units represented by the general formula (2) above is not particularly limited; it may be added all at once to the solution containing the platinum-phosphite complex, or it may be added in portions, or it may be added dropwise over a predetermined period of time; however, because dropwise addition takes a long time, it is preferable to add it all at once or add it in portions.

[0057] In this step, the dispersion and dissolution are preferably carried out at a temperature of 40°C or less, particularly 0 to 35°C, for 60 minutes or more, particularly 60 minutes to 24 hours. By carrying out the dispersion and dissolution under the above conditions, an association of at least a portion of the platinum-phosphite ester complex with an organopolysiloxane compound having a unit represented by general formula (2) can be obtained. As with the first and second steps, it is preferable to select a container for this step that can block oxygen, and the container used in the first or second step can be used as is.

[0058] By dispersing and dissolving under the above conditions, a solution containing an association of at least a portion of the platinum-phosphite ester complex and an organopolysiloxane compound having units represented by the general formula (2) can be prepared.

[0059] Fourth step:(d) The fourth step is a step of removing the hydrocarbon organic solvent from the solution obtained in step (c). This step is essential for removing the hydrocarbon organic solvent from the solution obtained in steps (a) to (c) and obtaining a platinum-phosphite complex-containing hydrosilylation catalyst that is free of the hydrocarbon organic solvent.

[0060] The solvent removal method used here is preferably a reduced-pressure distillation method in which the solvent is distilled off under reduced pressure using a vacuum pump or the like. This is because a stable platinum-phosphite complex-containing hydrosilylation catalyst can be obtained by setting the reduced-pressure distillation temperature at 40°C or less, preferably 0 to 35°C. The reduced-pressure distillation time is not particularly limited, but is preferably 30 minutes to 4 hours. The degree of vacuum varies depending on the boiling point of the hydrocarbon organic solvent used, but by setting the pressure at 50 hPa or less, preferably 1 to 35 hPa, the hydrocarbon organic solvent used can be completely removed.

[0061] Whether the hydrocarbon organic solvent used has been completely removed can be confirmed by the mass ratio of the total mass of the phosphite compound, platinum catalyst, and siloxane compound used to the mass of the platinum-phosphite complex-containing hydrosilylation catalyst obtained after completion of Step 4. If the mass of the resulting platinum-phosphite complex-containing hydrosilylation catalyst is greater than the total mass of the phosphite compound, platinum catalyst, and siloxane compound used, residual hydrocarbon organic solvent remains, and complete removal of the hydrocarbon organic solvent can be achieved by further extending the time of this step to remove it.

[0062] [Method for inhibiting crystallization of platinum-phosphite complex-containing hydrosilylation catalysts] Crystallization of the aforementioned platinum-phosphite complex-containing hydrosilylation catalyst can be suppressed by carrying out the following four steps. (a) preparing a solution of the phosphite compound represented by the general formula (1) in a hydrocarbon organic solvent having a boiling point of 80°C or less; (b) adding platinum chloride, platinum chloride to the solution; Sour a step of adding, dispersing, and dissolving a platinum catalyst containing no hydrocarbon organic solvent, selected from one or more platinum-alkenyl group-containing siloxane complexes formed from chloroplatinic acid salts and alkenyl group-containing siloxanes, to prepare a solution containing a platinum-phosphite complex composed of platinum and the phosphite compound represented by the general formula (1); (c) adding an organopolysiloxane compound having a unit represented by the general formula (2) to the solution obtained in the step (b), and dispersing and dissolving the compound to prepare a solution containing an association of at least a portion of the platinum-phosphite ester complex and the organopolysiloxane compound having a unit represented by the general formula (2); and (d) A step of removing the hydrocarbon organic solvent from the solution obtained in step (c).

[0063] The above four steps for suppressing crystallization are the same as the four steps shown in the above method for producing a platinum-phosphite complex-containing hydrosilylation catalyst. The above-mentioned step can suppress crystallization of the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention.

[0064] [Curable organopolysiloxane composition containing a platinum-phosphite complex-containing hydrosilylation catalyst] The platinum-phosphite complex-containing hydrosilylation catalyst described above can be used in applications such as curing catalysts for various resins and purification catalysts, but its characteristics are particularly apparent when used as a curing catalyst for one-component (one-liquid) addition reaction curable curable organopolysiloxane compositions (e.g., millable (raw rubber-like) or liquid addition curable silicone rubber compositions or addition curable silicone gel compositions) that can be cured into silicone resins (e.g., silicone rubber, silicone gel, etc.) using a hydrosilylation reaction. Furthermore, it is preferable that the curable organopolysiloxane composition does not contain a hydrocarbon organic solvent.

[0065] The reason is that (1) when heating, the platinum chloride, which was previously used, Sour(2) The platinum catalyst (compound) exhibits curability (catalytic activity for hydrosilylation addition reactions) substantially equivalent to that of a platinum catalyst selected from one or more platinum-alkenyl group-containing siloxane complexes formed from a chloroplatinate salt and an alkenyl group-containing siloxane. Furthermore, (2) during storage at room temperature, the phosphite ester compound forms a complex with platinum (platinum-phosphite ester complex), resulting in poor catalytic activity (excellent storage stability) and extremely slow progress of the hydrosilylation reaction. Therefore, the resulting curable organopolysiloxane composition maintains stable properties even after prolonged exposure to room temperature. Furthermore, (3) by associating the platinum-phosphite ester complex with an organopolysiloxane compound having a unit represented by general formula (2) (an organopolysiloxane compound having two or more adjacent alkenyl groups), the resulting platinum-phosphite ester complex-containing hydrosilylation catalyst can be maintained in a liquid state at 23°C. Therefore, when this platinum-phosphite complex-containing hydrosilylation catalyst is used in a curable organopolysiloxane composition, it offers the advantages of improved workability and ease of uniform dispersion.

[0066] Here, particularly preferred curable organopolysiloxane compositions (e.g., addition-curable silicone rubber compositions, addition-curable silicone gel compositions, etc.) are millable (raw rubber-like) or liquid (one-component) addition-reaction-type organopolysiloxane compositions that contain, as basic constituents, an alkenyl-containing organopolysiloxane as the main component (base polymer), such as a linear dimethylpolysiloxane capped at both molecular chain terminals with vinyldimethylsiloxy groups, and, as the curing agent (crosslinking agent), an organohydrogenpolysiloxane having two or more silicon-bonded hydrogen atoms (i.e., SiH groups) per molecule, and a hydrosilylation addition reaction catalyst, and that cure via a hydrosilylation reaction between the alkenyl groups in the alkenyl-containing organopolysiloxane (base polymer) and the silicon-bonded hydrogen atoms (SiH groups) present in the organohydrogenpolysiloxane (crosslinking agent) to give a silicone rubber elastomer (cured rubber product) or a cured silicone gel product.

[0067] The amount of the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention that is blended into a curable organopolysiloxane composition is preferably 0.1 to 1,000 ppm, more preferably 1 to 500 ppm, and even more preferably 5 to 300 ppm, calculated as the mass of platinum atoms in the platinum-phosphite complex-containing hydrosilylation catalyst relative to the total mass of the composition. When the catalyst is used in the form of a catalyst solution, such as a silicone solution containing a solvent other than a hydrocarbon organic solvent, such as an organic solvent (e.g., oil), for example, when the platinum-phosphite complex-containing hydrosilylation catalyst is used in a catalyst solution having a platinum atom concentration of 1 mass %, the amount of the catalyst solution added is preferably 0.001 to 10 parts by mass, more preferably 0.01 to 5 parts by mass, and even more preferably 0.05 to 3 parts by mass per 100 parts by mass of the alkenyl group-containing organopolysiloxane (base polymer). If the amount of platinum-phosphite complex-containing hydrosilylation catalyst solution (1% by mass of platinum atoms) is less than 0.001 part by mass (or if the mass of platinum atoms relative to the total composition is less than 0.1 ppm), the strength of the cured product of the resulting curable organopolysiloxane composition may decrease or the composition may not cure properly. Conversely, if the amount of platinum-phosphite complex-containing hydrosilylation catalyst solution (1% by mass of platinum atoms) exceeds 10 parts by mass (or if the mass of platinum atoms is 1,000 ppm), the resulting curable organopolysiloxane composition may become discolored, the time to cure may be shortened, and the cost may be unfavorable. Note that the activity of the catalyst, i.e., the curability, can be controlled by increasing or decreasing the concentration of the platinum-phosphite complex-containing hydrosilylation catalyst added.

[0068] The addition reaction organopolysiloxane composition containing the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention may further contain, as necessary, various fillers such as silica-based fillers such as fumed silica (dry silica), precipitated silica (wet silica), sol-gel silica, fused silica, crushed silica, and crystalline silica (finely powdered quartz); reinforcing inorganic fillers such as calcium carbonate and fumed titanium dioxide; and non-reinforcing inorganic fillers such as calcium silicate, titanium dioxide, ferric oxide, and carbon black, which may or may not have been surface-hydrophobized or untreated inorganic fillers, as well as various fillers such as organic resin balloons; silane coupling agents (for example, monovalent hydrocarbons having a functional group (e.g., epoxy group, (meth)acryloxy group, mercapto group) containing a heteroatom selected from oxygen, nitrogen, and sulfur atoms); Optional ingredients that can be blended include adhesion promoters such as hydrolyzable organosilane compounds such as alkoxysilanes containing alkyl groups and / or their partial hydrolysis condensates, plasticizers such as non-functional silicone oils that do not contain functional groups involved in hydrosilylation addition reactions, such as alkenyl groups or hydrosilyl groups (SiH groups), such as dimethylpolysiloxanes terminally capped with trimethylsilyl groups (dimethylsilicone oil), dimethylsiloxane-diphenylsiloxane copolymers terminally capped with trimethylsilyl groups, and dimethylsiloxane-methylphenylsiloxane copolymers terminally capped with trimethylsilyl groups (methylphenylsilicone oil), dispersants (wetters), addition reaction regulators, pigment pastes, reinforcing silicone resins, and other additives.

[0069] A suitable curing condition for the curable organopolysiloxane composition containing the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention is to accelerate curing by heating, with a heating temperature of, for example, about 80 to 200° C., and particularly about 90 to 150° C. There are no particular restrictions on the curing time, but a period of, for example, 5 to 240 minutes, and particularly about 10 to 120 minutes, is preferred.

[0070] [Article Having a Cured Product of a Curable Organopolysiloxane Composition Containing a Platinum-Phosphite Complex-Containing Hydrosilylation Catalyst] The curable organopolysiloxane compositions containing the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention can be used in articles such as potting materials for electrical and electronic devices and IGBTs; adhesive articles used in various electronic substrates and resin cases; rubber contacts used as rubber contacts in remote controllers, typewriters, word processors, computer terminals, musical instruments, etc.; construction gaskets; various rolls such as copier rolls, developing rolls, transfer rolls, charging rolls, and paper feed rolls; vibration-isolating rubber for audio equipment, etc.; packing for compact discs used in computers; polymer insulators used in electrical wires, etc.; and articles used in medical equipment, such as rubber hoses and nipples. [Example]

[0071] The present invention will be described in more detail below with reference to examples and comparative examples in order to clarify the effects of the present invention, but the present invention is not limited thereto. In the examples, "parts" means "parts by mass" and "%" means "% by mass" unless otherwise specified.

[0072] [Example 1] 0.3311 parts of tris(2,4-di-tert-butylphenyl)phosphite were weighed into a transparent glass container, and 9.6689 parts of n-hexane (boiling point: 68°C) were added. The container was sealed and allowed to dissolve at room temperature (23°C) for approximately 1 hour. After visually confirming that the tris(2,4-di-tert-butylphenyl)phosphite crystals had dissolved, 10.0 parts of a silicone solution of platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex (Karstedt complex) containing 1% by weight of Pt atoms (solvent: dimethylpolysiloxane capped with vinyldimethylsiloxy groups at both ends and with a degree of polymerization of 180) was added. The container was sealed and stirred for 30 minutes to ensure uniformity. 0.0088 parts of 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane was then added, sealed, and stirred for 60 minutes to ensure uniformity. The solution was then transferred to a 100 ml eggplant-shaped flask, and n-hexane was removed under reduced pressure using a rotary evaporator (conditions: 30°C x 2 hours / approximately 35 hPa). 10.33 g of a colorless, transparent liquid was obtained in the 100 ml eggplant-shaped flask (yield as catalyst solution (hereinafter the same): 99.9%). This silicone solution of platinum-phosphite complex-containing hydrosilylation catalyst is referred to as "Catalyst I." (The amount of the phosphite ester compound to be blended is 1.0 mol per mol of platinum atoms in the platinum catalyst, and the amount of the vicinal alkenyl group-containing organopolysiloxane compound to be blended is 0.05 mol per mol of platinum atoms in the platinum catalyst.)

[0073] [Example 2] 0.3311 parts of tris(2,4-di-tert-butylphenyl)phosphite were weighed into a transparent glass container, and 9.6689 parts of n-hexane were added. The container was sealed and allowed to dissolve at room temperature for approximately 1 hour. After visually confirming that the tris(2,4-di-tert-butylphenyl)phosphite crystals had dissolved, 10.0 parts of a silicone solution of platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex (Karstedt complex) containing 1% by weight of Pt atoms (solvent: dimethylpolysiloxane capped with vinyldimethylsiloxy groups at both ends and with a degree of polymerization of 180) was added. The container was sealed and stirred for 30 minutes to ensure uniformity. 0.1765 parts of 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane was then added, sealed, and stirred for 60 minutes to ensure uniformity. The solution was then transferred to a 100 ml eggplant-shaped flask, and the n-hexane was removed under reduced pressure using a rotary evaporator (conditions: 30°C x 2 hours / approximately 32 hPa). 10.46 g of a colorless, transparent liquid was obtained in the 100 ml eggplant-shaped flask (yield: 99.5%). This silicone solution of platinum-phosphite complex-containing hydrosilylation catalyst was designated "Catalyst II." (The amount of the phosphite ester compound to be blended is 1.0 mole per mole of platinum atoms in the platinum catalyst, and the amount of the vicinal alkenyl group-containing organopolysiloxane compound to be blended is 1.0 mole per mole of platinum atoms in the platinum catalyst.)

[0074] [Example 3] 0.3311 parts of tris(2,4-di-tert-butylphenyl)phosphite were weighed into a transparent glass container, and 9.6689 parts of n-hexane were added. The container was sealed and allowed to dissolve at room temperature for approximately 1 hour. After visually confirming that the tris(2,4-di-tert-butylphenyl)phosphite crystals had dissolved, 10.0 parts of a silicone solution of platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex (Karstedt complex) containing 1% by weight of Pt atoms (solvent: dimethylpolysiloxane capped with vinyldimethylsiloxy groups at both ends and with a degree of polymerization of 180) was added. The container was sealed and stirred for 30 minutes to ensure uniformity. 2.50 parts of 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane were then added, sealed, and stirred for 60 minutes to ensure uniformity. The solution was then transferred to a 100 ml eggplant-shaped flask, and the n-hexane was removed under reduced pressure using a rotary evaporator (conditions: 30°C x 2 hours / approximately 34 hPa). 12.80 g of a colorless, transparent liquid was obtained in the 100 ml eggplant-shaped flask (yield: 99.8%). This silicone solution of platinum-phosphite complex-containing hydrosilylation catalyst was designated "Catalyst III." (The amount of the phosphite ester compound added was 1.0 mole per mole of platinum atom in the platinum catalyst, and the amount of the vicinal alkenyl group-containing organopolysiloxane compound added was 14.2 moles per mole of platinum atom in the platinum catalyst.)

[0075] [Comparative Example 1] The same procedure as in Example 1 was carried out, except that 0.0088 parts of 1,1,3,3,5,5,7,7-octamethylcyclotetrasiloxane was used instead of 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane. As a result, 10.33 g of a colorless, transparent liquid was obtained in a 100 ml eggplant-shaped flask (yield: 99.9%). This silicone solution of a platinum-phosphite complex-containing hydrosilylation catalyst is designated "Catalyst IV." (The amount of the phosphite ester compound added is 1.0 mole per mole of platinum atoms in the platinum catalyst, and the amount of the vicinal alkenyl group-containing organopolysiloxane compound added is 0 mole per mole of platinum atoms in the platinum catalyst.)

[0076] Comparative Example 2 The same procedure as in Example 1 was carried out, except that 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane was not added. As a result, 10.33 g of a colorless, transparent liquid was obtained in a 100 ml eggplant-shaped flask (yield: 99.9%). This silicone solution of a platinum-phosphite complex-containing hydrosilylation catalyst was designated "Catalyst V." (The amount of the phosphite ester compound added is 1.0 mole per mole of platinum atoms in the platinum catalyst, and the amount of the vicinal alkenyl group-containing organopolysiloxane compound added is 0 mole per mole of platinum atoms in the platinum catalyst.)

[0077] Comparative Example 3 0.3311 parts of tris(2,4-di-tert-butylphenyl)phosphite were weighed into a transparent glass container, and 9.6689 parts of n-heptane (boiling point: 98°C) was added. The container was sealed and allowed to dissolve at room temperature for approximately 1 hour. After visually confirming that the tris(2,4-di-tert-butylphenyl)phosphite crystals had dissolved, 10.0 parts of a silicone solution of platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex (Karstedt complex) containing 1% by weight of Pt atoms (solvent: dimethylpolysiloxane with a degree of polymerization of 180 and capped at both ends with vinyldimethylsiloxy groups) was added. The container was sealed and stirred for 30 minutes to ensure uniformity. 0.0088 parts of 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane was then added, sealed, and stirred for 60 minutes to ensure uniformity. The solution was then transferred to a 100 ml eggplant-shaped flask and evaporated using a rotary evaporator. ヘプタン The solvent was distilled off under reduced pressure (conditions: 50°C x 2 hours / approximately 35 hPa). A colorless, transparent liquid with dispersed white crystals (yield: 10.96 g) was obtained in a 100 ml eggplant-shaped flask; a colorless, transparent liquid without precipitated crystals was not obtained (yield: 106.0%). This silicone solution of platinum-phosphite complex-containing hydrosilylation catalyst was designated "Catalyst VI." (The amount of the phosphite ester compound to be blended is 1.0 mol per mol of platinum atoms in the platinum catalyst, and the amount of the vicinal alkenyl group-containing organopolysiloxane compound to be blended is 0.05 mol per mol of platinum atoms in the platinum catalyst.)

[0078] Comparative Example 4 The same procedure as in Example 1 was carried out, except that n-hexane was not added. As a result, a colorless, transparent liquid (yield: 10.33 g) containing dispersed white crystals was obtained in a 100 ml eggplant-shaped flask; a colorless, transparent liquid without precipitated crystals was not obtained (yield: 99.9%). This silicone solution of a platinum-phosphite complex-containing hydrosilylation catalyst is designated "Catalyst VII." (The amount of the phosphite ester compound added is 1.0 mole per mole of platinum atoms in the platinum catalyst, and the amount of the vicinal alkenyl group-containing organopolysiloxane compound added is 0.05 moles per mole of platinum atoms in the platinum catalyst.)

[0079] [test] The following tests were carried out using the silicone solutions of the platinum-phosphite complex-containing hydrosilylation catalysts (Catalysts I to VII) obtained in Examples 1 to 3 and Comparative Examples 1 to 4. The results, along with the yields, are shown in Table 1. 〔exterior〕 The resulting platinum-phosphite complex-containing hydrosilylation catalysts were all stored in sealed containers filled with nitrogen. The appearance was then checked immediately after production (23°C), after 3 days, and after 3 months at 23°C. Those that showed no crystal formation in the container were judged to pass, and those that showed crystal formation in the container were judged to fail.

[0080] [Table 1]

[0081] [evaluation] The platinum-phosphite complex-containing hydrosilylation catalysts obtained in Examples 1 to 3 satisfy the requirements of the present invention. In all of Examples 1 to 3, the amount of phosphite compound blended was 1.0 mole per mole of platinum atom in the platinum catalyst. The platinum-phosphite complex-containing hydrosilylation catalysts obtained in Examples 1 to 3 showed suppressed crystal precipitation even after being left at 23°C for 3 months under sealed conditions, demonstrating that platinum-phosphite complex-containing hydrosilylation catalysts with highly stable properties were obtained. The platinum-phosphite complex-containing hydrosilylation catalysts were prepared in the same manner as in Example 1, except that the amount of the phosphite compound was varied in 0.1 mol increments from 1.0 mol to 1.9 mol per mol of platinum atom in the platinum catalyst. All of the catalysts yielded colorless, transparent liquids at 23°C, and it was confirmed that these remained colorless, transparent liquids even after 3 months at 23°C. In contrast, the platinum-phosphite complex-containing hydrosilylation catalysts of Comparative Examples 1 and 2 did not contain an organopolysiloxane compound (organopolysiloxane compound containing a vicinal alkenyl group) having a unit represented by general formula (2). Therefore, although a colorless, transparent liquid platinum-phosphite complex-containing hydrosilylation catalyst was obtained initially, the catalyst exhibited poor long-term property stability, resulting in the precipitation of crystals over time. Furthermore, the platinum-phosphite complex-containing hydrosilylation catalyst of Comparative Example 3 used n-heptane, which has a boiling point above 80°C, as the hydrocarbon organic solvent for dissolving the phosphite compound. Therefore, even when the temperature for vacuum distillation was increased, the n-heptane used could not be completely distilled off. As a result of increasing the heating temperature, the phosphite compound in the platinum-phosphite complex-containing hydrosilylation catalyst lost its coordination, resulting in the precipitation of crystals, and a liquid platinum-phosphite complex-containing hydrosilylation catalyst could not be obtained. In the case of the platinum-phosphite complex-containing hydrosilylation catalyst of Comparative Example 4, the phosphite compound was coordinated to the platinum catalyst without being dissolved in a hydrocarbon organic solvent, but the phosphite compound did not dissolve and a liquid containing dispersed crystals was obtained. As is clear from the above results, the present invention provides a stable, liquid platinum-phosphite complex-containing hydrosilylation catalyst.

[0082] [Examples of Curable Organopolysiloxane Compositions Utilizing Platinum-Phosphite Complex-Containing Hydrosilylation Catalysts] In order to clarify the effects of the platinum-phosphite ester complex-containing hydrosilylation catalyst obtained by the present invention, examples and comparative examples relating to curable organopolysiloxane compositions that utilize this catalyst (stored in a sealed container at 23°C for 3 months) are described in further detail below. Note that although the following examples and comparative examples are of one-component millable curable organopolysiloxane compositions, the present invention is not limited thereto.

[0083] [Composition Example 1] 100 parts by mass of dimethylpolysiloxane gum having an average degree of polymerization of 6,000, which is composed of 99.85 mol% dimethylsiloxane units, 0.125 mol% methylvinylsiloxane units, and 0.025 mol% dimethylvinylsiloxy units, and a BET specific surface area of ​​200 m 2 55 parts by mass of 1 / g fumed silica (Aerosil 200, manufactured by Nippon Aerosil Co., Ltd.), 12 parts by mass of dimethyldimethoxysilane (surface treatment agent), 0.2 parts by mass of vinyltrimethoxysilane (surface treatment agent), 12 parts by mass of dimethylpolysiloxane (dispersant) having silanol groups at both ends, an average degree of polymerization of 4, and a viscosity at 23°C of 15 mPa s, and 0.15 parts by mass of 3% by mass potassium siliconate were added, and the mixture was heated with mixing in a kneader at 170°C for 2 hours to prepare base compound (1).

[0084] To 100 parts by mass of dimethylpolysiloxane raw rubber, 1.7 parts by mass of organohydrogensiloxane represented by the following formula (SiH content: 0.00726 mol / g), 0.05 parts by mass of "Catalyst I" prepared in Example 1, and 0.00080 parts by mass of ethynylmethyldecylcarbinol (addition reaction inhibitor) were added to the base compound (1), and the mixture was mixed uniformly using a twin roll mill to produce a raw rubber-like one-component millable curable organopolysiloxane composition I. [ka]

[0085] Composition Example 2 A one-component millable curable organopolysiloxane composition II was produced in the same manner as in Composition Example 1, except that 0.05 parts by mass of "Catalyst II" prepared in Example 2 was used instead of "Catalyst I."

[0086] Composition Example 3 A one-component millable curable organopolysiloxane composition III was produced in the same manner as in Composition Example 1, except that 0.05 parts by mass of “Catalyst III” prepared in Example 3 was used instead of “Catalyst I.”

[0087] [Comparative Composition Example 1] A one-component millable curable organopolysiloxane composition IV was produced in the same manner as in composition example 1, except that 0.05 parts by mass of "catalyst IV" prepared in comparative example 1 was used instead of "catalyst I."

[0088] [Comparative Composition Example 2] A one-component millable curable organopolysiloxane composition V was produced in the same manner as in composition example 1, except that 0.05 parts by mass of "catalyst V" prepared in comparative example 2 was used instead of "catalyst I."

[0089] [Comparative Composition Example 3] A one-component millable curable organopolysiloxane composition VI was produced in the same manner as in Composition Example 1, except that 0.05 parts by mass of “Catalyst VI” prepared in Comparative Example 3 was used instead of “Catalyst I.”

[0090] [Comparative Composition Example 4] A one-component millable curable organopolysiloxane composition VII was produced in the same manner as in Composition Example 1, except that 0.05 parts by mass of “Catalyst VII” prepared in Comparative Example 4 was used instead of “Catalyst I.”

[0091] [Comparative Composition Example 5] One-component millable curable organopolysiloxane composition VIII was prepared in the same manner as in composition example 1, except that 0.05 parts by mass of a solution of platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex (Karstedt complex) containing 1% by mass of Pt atoms (solvent: dimethylpolysiloxane with a degree of polymerization of 180 and capped at both ends with vinyldimethylsiloxy groups) was used in place of "catalyst I."

[0092] [test] The following tests were carried out using the one-component millable curable organopolysiloxane compositions obtained in Composition Examples 1 to 3 and Comparative Composition Examples 1 to 5. The results are shown in Table 2, along with a pass / fail rating for the appearance of the catalyst.

[0093] [Workability when preparing one-component millable curable organopolysiloxane compositions (workability when adding catalyst)] When preparing the one-component millable curable organopolysiloxane compositions prepared in the above Composition Examples 1 to 3 and Comparative Composition Examples 1 to 5, compositions in which the platinum-phosphite complex-containing hydrosilylation catalyst was liquid at 23°C and no problems occurred when added were judged to pass, whereas compositions in which the platinum-phosphite complex-containing hydrosilylation catalyst crystallized and problems occurred in workability when added were judged to fail.

[0094] [Storage stability of one-component millable curable organopolysiloxane compositions] The storage stability (curability after storage) of the one-component millable curable organopolysiloxane compositions prepared in Composition Examples 1 to 3 and Comparative Composition Examples 1 to 5 was evaluated by measuring the initial curability of the resulting one-component millable curable organopolysiloxane compositions and their curability after 6 months of storage at 23°C using a rheometer (ALPHA TECHNOLOGIES RUBBER PROCESS ANALYZER RPA2000) at a measurement temperature of 150°C. The curing torque of the one-component millable curable organopolysiloxane composition was measured over time, and the time (T50) from the start of measurement to reach 50% of the maximum torque value was confirmed and compared. Furthermore, compositions that could be evaluated after 6 months at 23°C were judged to pass.

[0095] [Table 2]

[0096] [Composition Evaluation] The platinum-phosphite ester complex-containing hydrosilylation catalysts obtained in Examples 1 to 3 fulfilled the requirements of the present invention, and the one-component millable curable organopolysiloxane compositions of Examples 1 to 3 using them were confirmed to have good workability when adding the catalyst, cure in 10 minutes at 150°C, and good curability. Furthermore, it was found that they also had good storage stability at 23°C (curability after storage). In contrast, the platinum-phosphite complex-containing hydrosilylation catalysts of Comparative Examples 1 to 3 failed the appearance judgment of the catalyst itself because crystals precipitated at 23°C after 3 months or immediately after production (23°C).Furthermore, when adding the catalyst to the composition, it was necessary to remove the precipitated crystalline component (solid) and blend only the required amount of the liquid component of the platinum-phosphite complex-containing hydrosilylation catalyst, so they also failed the workability test.In addition, the one-component millable curable organopolysiloxane compositions of Comparative Examples 1 to 3 that used these catalysts (liquid component only) showed good storage stability (curability after storage). Furthermore, the platinum-phosphite complex-containing hydrosilylation catalyst of Comparative Example 4 was prepared without using a hydrocarbon organic solvent, which resulted in poor complex formation between the phosphite compound and platinum. As a result, the one-component millable curable organopolysiloxane composition of Comparative Example 4 prepared using this catalyst failed to pass the workability test when adding the catalyst, and also had reduced storage stability (curability after storage). In the comparative composition 5, no complex was formed with the phosphite ester or associated with the siloxane compound, and platinum chloride, Sour is an example of a one-component millable curable organopolysiloxane composition that directly uses a platinum catalyst (Karstedt complex) itself that does not contain a hydrocarbon organic solvent and is selected from one or more platinum-alkenyl group-containing siloxane complexes formed from chloroplatinic acid salts and alkenyl group-containing siloxanes. One-component millable curable organopolysiloxane compositions produced using this catalyst exhibited good workability when the catalyst was added, but resulted in reduced storage stability (curability after storage). The above results demonstrate that the one-component millable curable organopolysiloxane composition using the platinum-phosphite complex-containing hydrosilylation catalyst obtained in accordance with the present invention exhibits excellent performance in terms of improved workability and storage stability. [Industrial Applicability]

[0097] The platinum-phosphite complex-containing hydrosilylation catalyst of the present invention, even though conventional platinum-phosphite complex-containing hydrosilylation catalysts tend to form crystals, can maintain liquid properties at 23°C without the use of hydrocarbon organic solvents. This improves the stability of the hydrosilylation catalyst itself, improves workability when producing curable organopolysiloxane compositions using this catalyst, and enables the production of highly safe curable organopolysiloxane compositions that are free of hydrocarbon organic solvents. This also minimizes adverse effects on the human body. Furthermore, the resulting hydrocarbon-free curable organopolysiloxane compositions exhibit stable properties and characteristics even when exposed to room temperature for extended periods of time, making them suitable for a wide range of applications, including electrical equipment, automobiles, construction, medicine, and food.

Claims

1. Platinum and the following general formula (1) 【Chemical 1】 (In the formula, R 1 are independently a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 3 carbon atoms. and a platinum-phosphite ester complex composed of a phosphite ester compound represented by the following general formula (2): 【Chemistry 2】 (In the formula, R 2 represents an alkenyl group having 2 to 10 carbon atoms, and R 3 is a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, and n is an integer from 2 to 200. The platinum-phosphite complex-containing hydrosilylation catalyst is a liquid at 23°C and does not contain any hydrocarbon organic solvents.

2. 2. The platinum-phosphite complex-containing hydrosilylation catalyst according to claim 1, wherein the organopolysiloxane compound having a unit represented by general formula (2) is a cyclic organopolysiloxane compound.

3. The platinum-phosphite complex-containing hydrosilylation catalyst according to claim 1, wherein at least a portion of the platinum-phosphite complex is associated with an organopolysiloxane compound having a unit represented by general formula (2).

4. The platinum-phosphite complex-containing hydrosilylation catalyst according to claim 3, wherein 0.01 to 100 mol % of the platinum-phosphite complex is associated with an organopolysiloxane compound having a unit represented by general formula (2).

5. 2. The platinum-phosphite complex-containing hydrosilylation catalyst according to claim 1, wherein the alkenyl group-containing siloxane compound further comprises 1,3-divinyl-1,1,3,3-tetramethyldisiloxane and / or 1,5-divinyl-1,1,3,3,5,5-hexamethyltrisiloxane.

6. A curable organopolysiloxane composition containing the platinum-phosphite complex-containing hydrosilylation catalyst according to any one of claims 1 to 5.

7. 7. The curable organopolysiloxane composition according to claim 6, which does not contain a hydrocarbon organic solvent.

8. An article comprising a cured product of the curable organopolysiloxane composition of claim 6.

9. A method for producing a platinum-phosphite complex-containing hydrosilylation catalyst, comprising the following steps (a) to (d): (a) preparing a solution of a phosphite ester compound represented by the following general formula (1) in a hydrocarbon organic solvent having a boiling point of 80°C or less; 【Chemistry 3】 (In the formula, R 1 are independently a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 3 carbon atoms. (b) adding to the solution a platinum catalyst containing no hydrocarbon organic solvent, the platinum catalyst being selected from one or more platinum-alkenyl group-containing siloxane complexes formed from platinum chloride, chloroplatinic acid or a chloroplatinate salt and an alkenyl group-containing siloxane, and dispersing and dissolving the catalyst to prepare a solution containing a platinum-phosphite complex composed of platinum and the phosphite compound represented by the general formula (1); (c) adding an organopolysiloxane compound having a unit represented by the following general formula (2) to the solution obtained in step (b), and dispersing and dissolving the compound to prepare a solution containing an association of at least a portion of the platinum-phosphite ester complex and the organopolysiloxane compound having a unit represented by the following general formula (2); 【Chemistry 4】 (In the formula, R 2 represents an alkenyl group having 2 to 10 carbon atoms, and R 3 is a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, and n is an integer from 2 to 200. and, (d) A step of removing the hydrocarbon organic solvent from the solution obtained in step (c).

10. The method for producing a platinum-phosphite complex-containing hydrosilylation catalyst according to claim 9, wherein 0.01 to 500 moles of an organopolysiloxane compound having a unit represented by general formula (2) are added per mole of platinum atoms in the platinum-phosphite complex.

11. A method for inhibiting crystallization of a platinum-phosphite complex-containing hydrosilylation catalyst, comprising the steps of: (a) preparing a solution of a phosphite ester compound represented by the following general formula (1) in a hydrocarbon organic solvent having a boiling point of 80°C or less; 【Chemistry 5】 (In the formula, R 1 are independently a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 3 carbon atoms. (b) adding to the solution a platinum catalyst containing no hydrocarbon organic solvent, the platinum catalyst being selected from one or more platinum-alkenyl group-containing siloxane complexes formed from platinum chloride, chloroplatinic acid or a chloroplatinate salt and an alkenyl group-containing siloxane, and dispersing and dissolving the catalyst to prepare a solution containing a platinum-phosphite complex composed of platinum and the phosphite compound represented by the general formula (1); (c) adding an organopolysiloxane compound having a unit represented by the following general formula (2) to the solution obtained in step (b), and dispersing and dissolving the compound to prepare a solution containing an association of at least a portion of the platinum-phosphite ester complex and the organopolysiloxane compound having a unit represented by the following general formula (2); 【Chemistry 6】 (In the formula, R 2 represents an alkenyl group having 2 to 10 carbon atoms, and R 3 is a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, and n is an integer from 2 to 200. and, (d) A step of removing the hydrocarbon organic solvent from the solution obtained in step (c).

12. The method for inhibiting crystallization of a platinum-phosphite complex-containing hydrosilylation catalyst according to claim 11, wherein 0.01 to 500 moles of an organopolysiloxane compound having a unit represented by general formula (2) are added per mole of platinum atoms in the platinum-phosphite complex.

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