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

Abstract

This platinum-phosphite complex-containing hydrosilylation catalyst is liquid at 23°C, does not contain a hydrocarbon-based organic solvent, and comprises: a platinum-phosphite complex formed of platinum and a phosphite compound having a specific structure; an alkenyl group-containing siloxane compound that is liquid at 23°C and that contains an organopolysiloxane compound having two or more adjacent alkenyl groups; and an acetylene alcohol having a melting point of 35°C or lower. The catalyst has excellent storage stability. By using the catalyst, it is possible to easily obtain a one-component type (one-liquid type) curable organopolysiloxane composition not containing a hydrocarbon-based organic solvent. Further, the obtained one-component type curable organopolysiloxane composition has stable physical properties and characteristics even in a state of being exposed to ordinary temperatures for a long period of time.

Description

[Technical Field]

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

[0002] Addition-curable silicone compositions (addition-curable organopolysiloxane compositions; the term "addition-curable silicone composition" used herein refers to compositions obtained by curing the composition, and the resulting cured product may be either a rubber-cured product (an elastomer) such as silicone rubber, or a gel-cured product (a low-stress non-elastic material that does not exhibit a significant rubber hardness value), with no restrictions on the hardness after curing) contain an organopolysiloxane having alkenyl groups bonded to silicon atoms as the main component (base polymer), an organohydrogenpolysiloxane having hydrosilyl groups (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 a cured product is obtained by the addition reaction of the hydrosilyl groups to the alkenyl groups. Silicone rubber, silicone gel, and other silicone cured products obtained by heat-curing this addition-curable silicone composition have excellent heat resistance, weather resistance, oil resistance, cold resistance, electrical insulation, and other properties. For this reason, addition-curable silicone compositions are used in a wide range of applications, including electrical and electronic components, optical components, building materials, and automotive sealing materials.

[0003] When one-component addition-curable silicone compositions such as those described above are exposed to high temperatures during storage, they can experience problems such as changes in properties, such as thickening and gelation, as well as changes in physical properties after curing. To avoid these problems, one approach is to create a mixed silicone composition by dividing the components into two or more components and mixing them immediately before use. Another approach is to transport one-component silicone compositions at low temperatures. The former approach raises concerns about changes in the physical properties of the cured silicone due to formulation variations or uneven mixing. Furthermore, it requires highly advanced formulation and mixing techniques, making it a material that is not suitable for everyone. The latter approach requires low-temperature storage from storage to use, which increases transportation and storage costs, making it commercially disadvantageous. Against this backdrop, there has been a growing demand in recent years for one-component addition-curable silicone compositions that maintain their properties and performance even when stored for long periods at room temperature (hereinafter referred to as 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, the above publication has the problem that the addition of an amine compound causes 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 with a platinum catalyst. However, this method has the problem that the activity of the catalyst obtained by heat-aging is unstable. Furthermore, the use of an organic peroxide in combination with the catalyst imposes handling restrictions. Furthermore, prolonged exposure to room temperature can cause thickening and gelation, so low-temperature conditions are 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 two publications mentioned above, thickening and gelation occur when exposed to room temperature for a long period of time, so low-temperature conditions are essential during storage and transportation to ensure 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 method uses a tin compound, there are concerns about its harmfulness to the human body. Furthermore, if the product is left exposed to room temperature for a long period of time, it will thicken and gel, so low-temperature conditions are essential during 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. The composition proposed in this method also thickens and gels when exposed to room temperature for a long period of time, so low-temperature conditions are essential during 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 tris(2,4-di-tert-butylphenyl) phosphite. 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 a hydrocarbon organic solvent such as xylene to dissolve tris(2,4-di-tert-butylphenyl) phosphite. This has led to the problem of hydrocarbon organic solvents being contained in the resulting silicone composition.

[0009] Recently, Japanese Patent Application Laid-Open No. 2021-042323 (Patent Document 9) proposes a method for improving storage stability by using a specific phosphite ester compound. While this method does dramatically improve storage stability, a high temperature of around 150°C is required to obtain a fully cured silicone product. Furthermore, due to the high hydrolysis potential of the phosphite ester compound, storage stability in air is poor.

[0010] Therefore, there is a demand for a platinum-phosphite complex-containing hydrosilylation catalyst that is free of hydrocarbon organic solvents and is liquid at 23°C. If such a catalyst could be obtained, it would be possible to obtain a one-component addition-curable silicone composition that is free of hydrocarbon organic solvents and has stable properties and physical characteristics. Therefore, there has been a growing demand for a platinum-phosphite complex-containing hydrosilylation catalyst that is free of hydrocarbon organic solvents and is liquid at 23°C. [Prior art documents] [Patent documents]

[0011] [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] Japanese Patent Publication No. 2021-042323 Summary of the Invention [Problem to be solved by the invention]

[0012] 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, free of environmentally hazardous hydrocarbon organic solvents, and a method for producing the same. Another object is to provide a hydrocarbon-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 extended periods, as well as an article comprising the cured product. [Means for solving the problem]

[0013] The present inventors have conducted extensive research to achieve the above object and have come to the following findings. First, 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 compound represented by the following general formula (1) in a hydrocarbon organic solvent having a boiling point of 80°C or less. To this solution, a platinum catalyst containing no hydrocarbon organic solvent is added, and the platinum catalyst is selected from one or more platinum-alkenyl group-containing siloxane complexes formed from platinum chloride, chloroplatinic acid, or chloroplatinate salts and alkenyl group-containing siloxanes, and the mixture is dispersed and dissolved to prepare a solution containing a platinum-phosphite complex composed of platinum and the phosphite compound represented by the following general formula (1). To this complex solution, a platinum catalyst represented by the following general formula (2) is added. [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. An organopolysiloxane compound having a unit represented by the formula (2) is added to the platinum-phosphite complex and dispersed and dissolved therein to prepare a solution containing an association of the platinum-phosphite complex and the siloxane compound represented by the formula (2). Further, acetylene alcohol is added to the association solution and dispersed therein to stabilize the platinum-phosphite complex and the association of the platinum-phosphite complex and the siloxane compound represented by the formula (2). The hydrocarbon organic solvent having a boiling point of 80°C or less is then removed from the solution to obtain the desired platinum-phosphite complex-containing hydrosilylation catalyst of the present invention, which is liquid at 23°C and does not contain any 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 curable organopolysiloxane composition that does not contain a hydrocarbon organic solvent, and that the properties and physical characteristics of the obtained one-component curable organopolysiloxane composition remain stable even when exposed to room temperature for long periods of time, leading to the completion of the present invention. In this specification, the term "one-component composition" refers to a composition in which all components are configured as one composition, and is also called "one-liquid type."

[0014] Accordingly, the present invention provides the following platinum-phosphite complex-containing hydrosilylation catalyst and method for producing the hydrosilylation catalyst. The present invention also provides 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 formula: 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. an alkenyl group-containing siloxane compound that is liquid at 23°C, the alkenyl group-containing siloxane compound containing an organopolysiloxane compound having a unit represented by the formula: Acetylenic alcohol with a melting point of 35°C or less Made up of A platinum-phosphite complex-containing hydrosilylation catalyst that is liquid at 23°C and does not contain 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 0.01 to 100 mol % of the platinum-phosphite complex is associated with an organopolysiloxane compound having a unit represented by general formula (2). [4] The platinum-phosphite ester complex-containing hydrosilylation catalyst according to any one of [1] to [3], wherein the alkenyl group-containing siloxane compound further comprises at least one compound selected from the group consisting of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane and linear dimethylpolysiloxanes capped at both molecular chain terminals with dimethylvinylsiloxy groups. [5] The platinum-phosphite complex-containing hydrosilylation catalyst according to any one of [1] to [4], wherein the acetylene alcohol has one ethynyl group and one hydroxy group in one molecule. [6] The platinum-phosphite complex-containing hydrosilylation catalyst according to [1], wherein the organopolysiloxane compound having the unit represented by formula (2) is composed exclusively of the unit represented by formula (2) except for the molecular chain terminals. [7] The platinum-phosphite complex-containing hydrosilylation catalyst according to [1], wherein n in formula (2) is an integer of 4 to 10. [ 8 ] As a curing catalyst [1]~[ 7

[0023] The platinum-phosphite complex-containing hydrosilylation catalyst according to any one of

[0024] only A curable organopolysiloxane composition comprising: [ 9 ] Contains no hydrocarbon organic solvents 8 10. The curable organopolysiloxane composition according to claim 1, wherein the organopolysiloxane composition is a curable organopolysiloxane. [ 10 ] [ 8 ] or [ 9 10. An article comprising a cured product of the curable organopolysiloxane composition according to claim 1. [ 11 ] A method for producing a platinum-phosphite complex-containing hydrosilylation catalyst, comprising the following steps (a) to (e): (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 to the solution a platinum catalyst containing no hydrocarbon organic solvent, 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 product of a platinum-phosphite ester complex and an 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 R3 is a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, and n is an integer of 2 to 200. and, (d) adding an acetylenic alcohol having a melting point of 35°C or less to the solution obtained in step (c); (e) A step of removing the hydrocarbon organic solvent having a boiling point of 80°C or less from the solution obtained in step (d). [ 12 ] 0.01 to 500 moles of an organopolysiloxane compound having a unit represented by general formula (2) are added per mole of platinum atom in the platinum-phosphite complex. 11 10. A method for producing a platinum-phosphite complex-containing hydrosilylation catalyst according to claim 1, wherein the platinum-phosphite complex-containing hydrosilylation catalyst is a platinum-phosphite complex-containing hydrosilylation catalyst. [ 13 ] 0.50 to 800 moles of acetylene alcohol are added per mole of platinum atom in the platinum-phosphite ester complex. 11 ] or [ 12 10. A method for producing a platinum-phosphite complex-containing hydrosilylation catalyst according to claim 1, wherein the platinum-phosphite complex-containing hydrosilylation catalyst is a platinum-phosphite complex-containing hydrosilylation catalyst. [Effects of the Invention]

[0015] The platinum-phosphite complex-containing hydrosilylation catalyst of the present invention is liquid at 23°C even without the addition of hydrocarbon organic solvents, thereby providing excellent catalyst stability. In addition, the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention contains acetylene alcohol, providing excellent catalyst storage stability. Therefore, when the catalyst is incorporated into a one-component curable organopolysiloxane composition, it can be easily and uniformly dispersed while remaining stable, 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 for extended periods of time. Furthermore, the absence of hydrocarbon organic solvents allows for the production of extremely safe cured products. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 shows Pt-NMR profiles for each step in the preparation of the platinum-phosphite complex-containing hydrosilylation catalyst of Example 1, where (a) is a platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex solution, (b) is when the platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex solution is added to a solution containing a phosphite compound, (c) is when a vicinal alkenyl group-containing organopolysiloxane compound is further added, and (d) is when acetylene alcohol is further added. DETAILED DESCRIPTION OF THE INVENTION

[0017] [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. and an acetylene alcohol having a melting point of 35°C or less, and the platinum-phosphite complex-containing hydrosilylation catalyst is liquid at 23°C and does not contain any hydrocarbon organic solvent. In the present invention, a platinum-phosphite complex-containing hydrosilylation catalyst that is liquid at 23°C refers to a platinum-phosphite complex-containing hydrosilylation catalyst in which the platinum-phosphite complex and / or the phosphite compound are not crystallized (a state in which no crystallized components are present).

[0018] The platinum-phosphite complex-containing hydrosilylation catalyst of the present invention preferably comprises a platinum-phosphite complex associated with an organopolysiloxane compound having units represented by general formula (2); that is, the platinum-phosphite complex and the organopolysiloxane compound having units represented by general formula (2) preferably comprise an association of the platinum-phosphite complex and the platinum-phosphite complex with the siloxane compound represented by general formula (2), or more preferably comprise an association of the platinum-phosphite complex with the siloxane compound represented by general formula (2). Specifically, it is preferred that 0.01 to 100 mol %, and particularly 0.02 to 100 mol %, of the platinum-phosphite complex be associated with the organopolysiloxane compound having units represented by general formula (2). If the content is less than 0.01 mol%, the platinum-phosphite ester complex in the platinum-phosphite ester complex-containing hydrosilylation catalyst may crystallize and become cloudy during long-term storage. It is believed that an association complex is quantitatively and easily formed depending on the blend ratio between the platinum-phosphite ester complex and an organopolysiloxane compound having units represented by general formula (2) when the platinum-phosphite ester complex is dispersed or dissolved in the organopolysiloxane compound in a free (liquid) state and then contacted with the organopolysiloxane compound. The presence of this association complex is believed to suppress crystallization of the platinum-phosphite ester complex (see Examples 1, 2, and 3, described below). In contrast, alkenyl-containing siloxane compounds other than organopolysiloxane compounds having units represented by general formula (2) are believed not to effectively form association complexes even when in contact with the platinum-phosphite ester complex (see Comparative Example 1, described below).

[0019] In the present invention, by further adding an acetylene alcohol having a melting point of 35°C or less to the platinum-phosphite complex-containing hydrosilylation complex, it is possible to stabilize the complex state of the platinum-phosphite complex and also to stabilize the association state of the association product of the platinum-phosphite complex and the organopolysiloxane compound having a unit represented by general formula (2), thereby improving the storage stability of the catalyst.

[0020] Preferably, 0.01 to 100 mol %, and particularly 1.0 to 100 mol %, of the platinum-phosphite complex component contained in the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention is stabilized with the acetylene alcohol. If the amount is less than 0.01 mol %, the expected improvement in storage stability may not be achieved when used in a composition.

[0021] <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.

[0022] [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.

[0023] In the above formula (1), R 1are 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 methyl group.

[0024] 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 R are phosphite compounds having the same number of carbon atoms, and R is a phosphite compound 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, tris(2,4-di-tert-butylphenyl)phosphite is particularly preferred because it is easily available and has excellent storage stability.

[0025] 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, preferably 0.8 to 1.5 mol, per mol of platinum atom. If the amount is 0.6 mol or less, the resulting curable organopolysiloxane composition containing the platinum-phosphite complex-containing hydrosilylation catalyst may exhibit poor storage stability or gelation. 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, hereinafter the same) and may not be able to maintain its liquid (liquid phase state).

[0026] <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.

[0027] [Organopolysiloxane compounds] The organopolysiloxane compound contained in the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention is characterized by having a unit represented by the following general formula (2): This is an essential component that, by associating with the platinum-phosphite complex, prevents 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.

[0028] In the organopolysiloxane compound having a bifunctional siloxane unit represented by the general formula (2), n is 2 or more (i.e., [(R 2 )(R 3 )SiO 2 / 2 ]), and therefore, the organopolysiloxane has, in the molecule, two or more alkenyl groups (hereinafter sometimes referred to as adjacent alkenyl groups) bonded to silicon atoms at non-terminal locations (in the middle of the molecular chain) in adjacent bifunctional siloxane units that are connected to each other 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 (triorganosiloxy units or diorganohydroxysiloxy units).

[0029] In the above formula (2), R2 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, isobutenyl group, etc.), more preferably 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 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.

[0030] The terminals of the organopolysiloxane compound having the bifunctional siloxane unit represented by the general formula (2) are not particularly limited. For example, when the organopolysiloxane compound is linear or branched, the molecular chain terminals may be silanol-containing siloxy groups (diorganohydroxysiloxy groups) or triorganosiloxy groups such as trimethylsiloxy groups and dimethylvinylsiloxy groups. When the organopolysiloxane compound is cyclic, 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.

[0031] Specific examples of such organopolysiloxane compounds include organoalkenylcyclopolysiloxanes (where 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) that has been 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.

[0032] 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.

[0033] [Other alkenyl group-containing siloxane compounds] The alkenyl group-containing siloxane compound may include alkenyl group-containing siloxane compounds other than the organopolysiloxane compound having the unit represented by the general formula (2). Examples include vinyl group-containing disiloxanes 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, as well as linear dimethylpolysiloxanes capped at both molecular chain ends with dimethylvinylsiloxy groups. These vinyl group-containing disiloxanes are the same as those blended with the platinum catalyst used to prepare the platinum-phosphite complex in the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention.

[0034] The content of alkenyl group-containing siloxane compounds other than the organopolysiloxane compound having units represented by general formula (2) is preferably 0 to 5.0 mass%, and more preferably 0 to 3.0 mass%, of the alkenyl group-containing siloxane compound. If the content of this compound is too high, the purity of the organopolysiloxane compound having units represented by general formula (2) decreases, and the platinum-phosphite complex in the platinum-phosphite complex-containing hydrosilylation catalyst may crystallize and become cloudy during long-term storage.

[0035] <Acetylene alcohol> The acetylene alcohol contained in the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention is an essential component for stabilizing the platinum-phosphite complex and the association between the platinum-phosphite complex and the alkenyl group-containing siloxane compound. Acetylene alcohols are characterized by having a melting point of 35°C or lower. Among these, those having one ethynyl group with a carbon-carbon triple bond and one hydroxy group, which is an alcoholic hydroxyl group, per molecule are preferred. Considering that the platinum-phosphite ester complex and the association of the platinum-phosphite ester complex with the alkenyl group-containing siloxane compound are liquids at 23°C, the melting point of the acetylene alcohol must be 35°C or lower.

[0036] Specific examples of acetylene alcohols used in the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention include 1-ethynyl-1-cyclohexanol (melting point: 30°C), 3-methyltridec-1-yn-3-ol (melting point: no information, liquid at 20°C), 3-butyn-1-ol (melting point: -63.6°C), 2-methyl-3-butyn-2-ol (melting point: 2.6°C), and 3-methyl-1-pentadecyn-3-ol (melting point: no information, liquid at 20°C), with 1-ethynyl-1-cyclohexanol (melting point: 30°C) and 3-methyltridec-1-yn-3-ol (melting point: no information, liquid at 20°C) being more preferred. These may be used alone or in combination of two or more.

[0037] The content of acetylene alcohol used in the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention is preferably 0.50 to 800 moles, more preferably 1.0 to 500 moles, per mole of platinum atom in the platinum-phosphite complex. If the acetylene alcohol content is too high, the resulting platinum-phosphite complex-containing hydrosilylation catalyst may separate or form a precipitate, making it difficult to obtain a catalyst with uniform properties. Conversely, if the acetylene alcohol content is too low, it may take time to stabilize the resulting platinum-phosphite complex-containing hydrosilylation catalyst, causing variations in the storage stability of one-component curable organopolysiloxane compositions using this catalyst.

[0038] The platinum-phosphite complex-containing hydrosilylation catalyst of the present invention does not contain a hydrocarbon organic solvent. Hydrocarbon organic solvents are compounds consisting only of carbon and hydrogen, and examples thereof include the hydrocarbon organic solvents used to dissolve the phosphite compounds used in the method for producing the platinum-phosphite complex-containing hydrosilylation catalyst described below. Because the hydrocarbon organic solvent is a compound consisting only of carbon and hydrogen, it does not fall under the category of acetylene alcohols with melting points of 35°C or lower, or vinyl-containing siloxanes with approximately 2 to 4 silicon atoms, such as tetramethyldivinyldisiloxane, trimethyltrivinylcyclotrisiloxane, and tetramethyltetravinylcyclotetrasiloxane. Furthermore, "free of hydrocarbon organic solvents" means that the content of such hydrocarbon organic solvents is 1.0% by mass or less.

[0039] [Method for producing a platinum-phosphite complex-containing hydrosilylation catalyst] The platinum-phosphite complex-containing hydrosilylation catalyst described above can be produced stably through the following five 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 to the solution a platinum catalyst containing no hydrocarbon organic solvent, 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 general formula (2) to the solution obtained in the step (b), and dispersing and dissolving the compound to prepare a solution containing an association product of a platinum-phosphite ester complex and an organopolysiloxane compound having a unit represented by the general formula (2); and (d) adding an acetylenic alcohol having a melting point of 35°C or less to the solution obtained in step (c); (e) A step of removing the hydrocarbon organic solvent having a boiling point of 80°C or less from the solution obtained in step (d).

[0040] 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.

[0041] 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.

[0042] [Phosphite ester compounds] The phosphite ester compound represented by the 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.

[0043] [Hydrocarbon organic solvents with a boiling point of 80°C or less] The phosphite compound represented by the general formula (1) is often solid at room temperature. Therefore, when mixing with a platinum catalyst (described later) to form a platinum-phosphite complex in the second step, the phosphite compound must be dissolved in a hydrocarbon organic solvent having a boiling point of 80°C or lower to form a solution. As mentioned above, hydrocarbon organic solvents are compounds consisting only of carbon and hydrogen, and therefore the acetylene alcohol used in the present invention, which has a melting point of 35°C or lower, does not fall under this category.

[0044] The hydrocarbon-based organic solvent having a boiling point of 80°C or less is primarily composed of a linear or branched saturated hydrocarbon, and preferably a linear or branched saturated hydrocarbon. Specific examples of hydrocarbon-based 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.

[0045] The reason why a boiling point of 80°C or less is necessary is that, in the step of removing the hydrocarbon organic solvent described below, it is preferable to remove the solvent by vacuum distillation, and by setting the vacuum distillation temperature at 50°C or less, the hydrocarbon organic solvent can be removed, 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 hydrocarbon organic solvent used cannot be completely removed unless the vacuum distillation temperature exceeds 50°C. This may result in the hydrocarbon organic solvent remaining in the platinum-phosphite complex-containing hydrosilylation catalyst, or the platinum-phosphite complex-containing hydrosilylation catalyst may decompose due to the thermal history of the solvent removal step, resulting in the precipitation of crystals.

[0046] 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).

[0047] The temperature at which the phosphite 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. If the phosphite compound is dissolved at a temperature higher than 40°C, the phosphite compound is likely to be hydrolyzed by the water contained in the hydrocarbon organic solvent. As a result, the phosphite compound is likely to be converted to a phosphate ester compound, and the stability of the resulting catalyst is reduced. The dissolution time is not particularly limited as long as the phosphite compound represented by general formula (1) is dissolved in the hydrocarbon organic solvent, and specifically, it is about 10 minutes to 24 hours. As for the container for dissolution, it is preferable to select a container that can block oxygen.

[0048] Second step: (b) The second step is a step of adding a platinum catalyst containing no hydrocarbon organic solvent, 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, to the solution obtained in step (a), 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) above.

[0049] [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 a platinum catalyst containing no hydrocarbon organic solvent, 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. This platinum catalyst is typically itself a curing catalyst contained in an addition-curable silicone composition, which contributes to the hydrosilylation addition reaction between alkenyl groups in the alkenyl group-containing organopolysiloxane base polymer and hydrosilyl groups in the organohydrogenpolysiloxane crosslinker.

[0050] 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, the properties and storage stability of the physical properties of the target curable organopolysiloxane composition can be significantly improved.

[0051] 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, 1,3,5-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]

[0052] In the platinum catalyst containing no hydrocarbon organic solvent, the platinum catalyst is selected from one or more platinum-alkenyl group-containing siloxane complexes formed from a platinum compound selected from platinum chloride (PtCl4), chloroplatinic acid (H2PtCl6), and chloroplatinic acid salt (H2PtCl6·6H2O) and an alkenyl group-containing siloxane such as a vinyl group-containing siloxane. Specific examples of the platinum-alkenyl group-containing siloxane complex include platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex (K Examples of suitable platinum catalysts include platinum-1,3-diallyl-1,1,3,3-tetramethyldisiloxane complexes (Karstedt complexes), platinum-1,3-divinyl-1,3-dimethyl-1,3-diphenyldisiloxane complexes, platinum-1,3,5-trimethyl-1,3,5-trivinylcyclotrisiloxane complexes, platinum-1,3-divinyl-1,1,3,3-tetraphenyldisiloxane complexes, and platinum-1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane complexes. 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 a hydrocarbon organic solvent. Among the platinum catalysts listed above, platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complexes (Karstedt complexes) are particularly preferred.

[0053] A preferred platinum catalyst, platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex (Karstedt complex), is believed to have the following structure: [ka]

[0054] The platinum catalysts shown here must be free of basic hydrocarbon organic solvents, such as aromatic hydrocarbon organic solvents such as toluene and xylene, and alcohol organic solvents such as ethanol, n-butanol, and 2-ethylhexyl alcohol, due to concerns that these may have adverse effects on the human body.

[0055] This hydrocarbon-based organic solvent-free platinum catalyst, selected from one or more platinum-alkenyl group-containing siloxane complexes formed from platinum chloride, chloroplatinic acid, or chloroplatinic salts and alkenyl group-containing siloxanes, is preferably in the form of a silicone solution using as a diluent (solvent) an alkenyl group-containing organopolysiloxane (typically a linear organopolysiloxane capped at both molecular terminals with vinyldiorganosiloxy groups and no adjacent alkenyl groups in the molecule, such as a linear dimethylpolysiloxane capped at both molecular terminals with dimethylvinylsiloxy groups) that is the same or different from the alkenyl group-containing siloxane that forms the ligand of the platinum-alkenyl group-containing siloxane complex. The platinum atom content of this solution is preferably 0.001 to 0.010 mol %. Converting this to mass %, the amount of platinum (mass concentration) contained in the silicone solution is approximately 0.2 to 2.0 mass %. Within this range, the stability of the platinum-alkenyl group-containing siloxane complex can be improved.

[0056] The optimum ratio of the platinum catalyst and phosphite ester compound to platinum atom in the platinum catalyst is greater than 0.6 molecules and less than 1.9 molecules, and more preferably, 0.8 to 1.5 molecules per platinum atom in the platinum catalyst. If the ratio of phosphite ester compound to platinum atom in the platinum catalyst is 0.6 molecules or less, the resulting curable organopolysiloxane composition containing the platinum-phosphite ester complex-containing hydrosilylation catalyst may have poor storage stability or may be at high risk of gelation. On the other hand, if the ratio of phosphite ester compound to platinum atom in the platinum catalyst is greater than 1.9 molecules, the platinum-phosphite ester complex-containing hydrosilylation catalyst may not be able to remain liquid at 23°C in the subsequent step. The reason for this is believed to be that even if the platinum-phosphite ester complex obtained in this step is associated with the organopolysiloxane compound, the platinum-phosphite ester complex in the resulting platinum-phosphite ester complex-containing hydrosilylation catalyst is likely to precipitate. Furthermore, when the platinum-phosphite ester complex-containing hydrosilylation catalyst is blended into a curable organopolysiloxane composition, problems such as poor dispersibility and reduced blending workability may occur.

[0057] In this step, there is no particular limitation on the method of adding the platinum catalyst, and it may be added all at once or added dropwise.

[0058] In this step, the dispersion and dissolution of the platinum catalyst is preferably carried out at a temperature of 40° C. or less, particularly 0 to 35° C., for 30 minutes or more, particularly 30 minutes to 4 hours. As in the first step, it is preferable to select a container for this step that can block oxygen, and the container used in the first step can be used as is.

[0059] 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.

[0060] Third step: (c) The third step is a step of 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 product of a platinum-phosphite ester complex and an 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.

[0061] The present invention provides a platinum-phosphite complex-containing hydrosilylation catalyst that is liquid at 23°C and has excellent dispersibility and property stability even without containing a hydrocarbon organic solvent, by associating at least a portion of the platinum-phosphite complex with an organopolysiloxane compound having units represented by the above general formula (2). Furthermore, when this platinum-phosphite complex-containing hydrosilylation catalyst is used as a curing catalyst in an addition-curable silicone composition, it provides a composition that has stable properties and physical characteristics even when exposed to room temperature for long periods of time, and it is possible to obtain a composition that does not contain a hydrocarbon organic solvent.

[0062] The organopolysiloxane compound having units represented by general formula (2) is as described above. The organopolysiloxane compound having units represented by general formula (2) is a component that associates with a platinum-phosphite ester complex to prevent crystallization of the platinum-phosphite ester complex. The organopolysiloxane compound is characterized in that, although it associates with the complex, the molecules are in a liquid state in which they are individually free. In this respect, it differs from alkenyl-containing siloxanes, such as vinyl-containing siloxanes, which serve as ligands that form complexes with platinum atoms in the platinum catalyst.

[0063] In step (b), when the alkenyl-containing siloxane, such as the vinyl-containing siloxane, which is a ligand in the platinum catalyst, is liberated from the platinum-phosphite ester complex, the following may occur depending on the structure of the liberated alkenyl-containing siloxane, such as the vinyl-containing siloxane. First, if the liberated alkenyl-containing siloxane, such as a vinyl-containing siloxane, is an alkenyl-containing siloxane, such as a vinyl-containing siloxane, other than an organopolysiloxane compound having a unit represented by general formula (2), it is believed that the alkenyl-containing siloxane, such as a vinyl-containing siloxane, will not associate with the platinum-phosphite complex, as described above. Therefore, by mixing and contacting it with an organopolysiloxane compound having a unit represented by general formula (2) in this step, it is possible to reliably form an association with the platinum-phosphite complex. On the other hand, if the released alkenyl-containing siloxane, such as a vinyl-containing siloxane, corresponds to an organopolysiloxane compound having units represented by general formula (2), it is believed that the alkenyl-containing siloxane, such as a vinyl-containing siloxane, can also form an association with the platinum-phosphite complex. In this case, the role of this step is to prepare a platinum-phosphite complex, and then mix and contact it with an organopolysiloxane compound having units represented by general formula (2), thereby more reliably forming an association with the platinum-phosphite complex.

[0064] The amount of organopolysiloxane compound having units represented by general formula (2) used is preferably 0.01 to 500 moles, particularly 0.02 to 50 moles, per mole of platinum atom in the platinum-phosphite complex obtained in the previous 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 very small. As a result, it becomes 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.

[0065] In this step, there are no particular limitations on the method for adding the organopolysiloxane compound having units represented by the general formula (2). It may be added all at once, or added dropwise. However, because dropwise addition takes time, it is preferable to add it all at once or add it.

[0066] 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.

[0067] By dispersing and dissolving under the above conditions, a solution containing an association product of the platinum-phosphite ester complex and the organopolysiloxane compound having the unit represented by the general formula (2) can be prepared.

[0068] Fourth step:(d) The fourth step is to add an acetylene alcohol having a melting point of 35°C or lower to the solution obtained in step (c), and by dispersing the acetylene alcohol, it is possible to stabilize the complex state of the platinum-phosphite ester complex in the solution and the association state of the association product of the platinum-phosphite ester complex and the organopolysiloxane compound having a unit represented by general formula (2). Such acetylene alcohols have a boiling point of more than 80°C, preferably 100°C or higher.

[0069] The amount of acetylene alcohol used is preferably 0.50 to 800 moles, particularly 1.0 to 500 moles, per mole of platinum atom in the platinum-phosphite complex obtained in the previous step. Less than 0.50 moles of acetylene alcohol per mole of platinum atom in the platinum-phosphite complex is undesirable because the storage stability of one-component curable organopolysiloxane compositions using the catalyst varies. Furthermore, more than 800 moles of acetylene alcohol may result in separation or precipitate formation in the resulting platinum-phosphite complex-containing hydrosilylation catalyst, making it difficult to obtain a uniform catalyst.

[0070] In this step, the method of adding acetylene alcohol is not particularly limited. It may be added all at once, or may be added dropwise. However, since the dropwise addition method takes time, it is preferable to add it all at once or add it.

[0071] In this step, the addition and dispersion are preferably carried out at a temperature of 40°C or below, particularly 0 to 35°C, for 10 minutes or longer, particularly 30 to 400 minutes. Addition and dispersion under the above conditions provides the resulting platinum-phosphite complex-containing hydrosilylation catalyst with excellent storage stability and property stability, and when added to a composition, dramatically improves the storage stability of the composition. As with the first, second, and third steps, it is preferable to select a container for this step that can block oxygen, and the container used in the first, second, or third steps can be used as is.

[0072] Fifth step: (e) The fifth step is a step of removing the hydrocarbon organic solvent having a boiling point of 80° C. or lower from the solution obtained in the previous step (d). This step is essential for removing the hydrocarbon organic solvent having a boiling point of 80° C. or lower from the solution obtained in steps (a) to (d) and obtaining a platinum-phosphite complex-containing hydrosilylation catalyst that is free of hydrocarbon organic solvents.

[0073] The solvent removal method used here is preferably a vacuum distillation method in which the solvent is distilled off under reduced pressure at low temperatures to avoid reactivating the platinum-phosphite complex-containing hydrosilylation catalyst stabilized in the previous step. The vacuum distillation temperature in this vacuum removal step must be 50°C or lower, preferably 0 to 45°C, to obtain a stable platinum-phosphite complex-containing hydrosilylation catalyst. The vacuum distillation time is not particularly limited, but is preferably 30 minutes to 4 hours. The pressure varies depending on the boiling point of the hydrocarbon organic solvent used, but by maintaining the pressure at 50 hPa or lower, preferably 1 to 30 hPa, the hydrocarbon organic solvent used can be completely removed. These conditions are preferably such that the acetylene alcohol added in the fourth step is not removed.

[0074] 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, siloxane compound, and acetylene alcohol used to the mass of the platinum-phosphite complex-containing hydrosilylation catalyst obtained after completion of Step 5. If the mass of the resulting platinum-phosphite complex-containing hydrosilylation catalyst is greater than the total mass of the phosphite compound, platinum catalyst, siloxane compound, and acetylene alcohol 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 the hydrocarbon organic solvent.

[0075] In the present invention, by associating at least a portion of the platinum-phosphite ester complex with an organopolysiloxane compound having units represented by the above general formula (2), the resulting mixture becomes liquid at 23°C, and then adding the above-mentioned acetylene alcohol, a platinum-phosphite ester complex-containing hydrosilylation catalyst with even better dispersibility and property stability can be obtained. When this platinum-phosphite ester complex-containing hydrosilylation catalyst is used as a curing catalyst in an addition-curable silicone composition, it gives a composition with even more stable properties and physical characteristics, even when exposed to room temperature for long periods of time, and it is possible to create a composition that does not contain hydrocarbon organic solvents.

[0076] [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 that undergo a hydrosilylation reaction to form silicone resins (silicone rubber or silicone gel). Furthermore, it is preferable that the curable organopolysiloxane composition does not contain hydrocarbon organic solvents, which place a heavy burden on the environment.

[0077] The reasons for this are mainly the following four points: (1) When heated, it has a curing property almost equivalent to that of a platinum catalyst selected from one or more of the platinum compounds selected from platinum chloride, chloroplatinic acid, and chloroplatinate salts, which have been conventionally used, and platinum-alkenyl group-containing siloxane complexes formed from alkenyl group-containing siloxanes such as vinyl group-containing siloxanes, and acetylene alcohols. (2) When stored at room temperature, the phosphite ester compound forms a complex with platinum, suppressing catalytic activity and causing the hydrosilylation reaction to proceed very slowly. As a result, the resulting curable organopolysiloxane composition maintains stable properties and characteristics even when exposed to room temperature for long periods of time. (3) By associating at least a portion of the platinum-phosphite complex with an organopolysiloxane compound having units represented by general formula (2), it becomes possible to maintain the state of the resulting platinum-phosphite complex-containing hydrosilylation catalyst in a liquid state at 23°C. (4) The platinum-phosphite ester complex and the associated complex of the platinum-phosphite ester complex with an organopolysiloxane compound having a unit represented by general formula (2) are stabilized with acetylene alcohol. This enhances the stability of the resulting platinum-phosphite ester complex-containing hydrosilylation catalyst, further improving the reactivity of the catalyst itself. Furthermore, the production stability of the platinum-phosphite ester complex-containing hydrosilylation catalyst can also be improved.

[0078] For the reasons described above, the use of the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention in a curable organopolysiloxane composition offers the advantages of improved workability and ease of uniform dispersion.

[0079] Here, the curable organopolysiloxane composition is particularly preferably a one-component addition reaction type organopolysiloxane composition that uses an organopolysiloxane containing an alkenyl group as the base polymer and is blended with an organohydrogenpolysiloxane that has a hydrogen atom bonded to a silicon atom (i.e., a hydrosilyl group) as the curing agent (crosslinking agent).

[0080] 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 about 5 to 300 ppm, calculated as the mass of platinum atoms in the platinum-phosphite complex-containing hydrosilylation catalyst relative to the entire composition. Furthermore, when the platinum-phosphite complex-containing hydrosilylation catalyst is used in the form of a catalyst solution, such as a silicone solution containing an alkenyl-terminated organopolysiloxane (alkenyl-terminated silicone oil) or other solvent other than a hydrocarbon organic solvent, for example, when the platinum-phosphite complex-containing hydrosilylation catalyst solution has a platinum atom concentration of 1% by mass, the amount of the catalyst solution 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 platinum atom) is less than 0.001 part by mass (or 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 be reduced or the curing may be insufficient. Conversely, if the amount of platinum-phosphite complex-containing hydrosilylation catalyst solution (1 mass % platinum atoms) exceeds 10 parts by mass (or 1,000 ppm platinum atoms), the resulting curable organopolysiloxane composition will become discolored, the time until curing will be shortened, and it will also be unaffordable in terms of cost. The activity of the catalyst, i.e., the curability, can be adjusted by increasing or decreasing the concentration of the platinum-phosphite complex-containing hydrosilylation catalyst added.

[0081] An example of the curable organopolysiloxane composition of the present invention is the following one-component millable silicone rubber composition. (A) 100 parts by mass of a linear diorganopolysiloxane gum having an average degree of polymerization of 100 or more and having at least two silicon-bonded alkenyl groups per molecule, (B) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms per molecule: 0.01 to 50 parts by mass; (C) Specific surface area is 50m 2 / g or more reinforcing silica: 5 to 100 parts by mass, (D) The platinum-phosphite complex-containing hydrosilylation catalyst of the present invention: 0.001 to 10 parts by mass

[0082] -(A) Linear diorganopolysiloxane raw rubber- The linear diorganopolysiloxane gum of component (A) is the main component (base polymer) of the composition, and contains at least two, preferably 2 to 10,000, and more preferably 2 to 500 silicon-bonded alkenyl groups per molecule, with an average degree of polymerization of 100 or greater.

[0083] The component (A) is preferably one represented by the following average composition formula (I). R 11 n1 SiO (4-n1) / 2 (I) (In formula (I), R 11 are each independently the same or different monovalent hydrocarbon groups having 1 to 20 carbon atoms, and n1 is a positive number of 1.95 to 2.04.

[0084] In the above average compositional formula (I), R 11 R are the same or different monovalent hydrocarbon groups having 1 to 20 carbon atoms, preferably 1 to 12, and more preferably 1 to 8 carbon atoms. 11Examples of the monovalent hydrocarbon group represented by the formula include alkyl groups such as methyl, ethyl, propyl, and butyl groups, cycloalkyl groups such as cyclohexyl groups, alkenyl groups such as vinyl, allyl, butenyl, and hexenyl groups, aryl groups such as phenyl and tolyl groups, and aralkyl groups such as β-phenylpropyl groups. In addition, some or all of the hydrogen atoms bonded to the carbon atoms of these groups may be substituted with halogen atoms, for example, 3,3,3-trifluoropropyl groups. Among these, methyl, vinyl, phenyl, and trifluoropropyl groups are preferred, and methyl and vinyl groups are more preferred. Among these, in particular, R 11 Of the monovalent hydrocarbon groups represented by the formula (I), those in which 50 mol % or more are methyl groups are preferred, more preferably 80 mol % or more are methyl groups, and particularly preferably 95 mol % or more are methyl groups. Furthermore, all R s other than alkenyl groups are 11 is preferably a methyl group.

[0085] In the above average composition formula (I), n1 is a positive number of 1.95 to 2.04, and preferably a positive number of 1.98 to 2.02. If the n1 value is outside the range of 1.95 to 2.04, the resulting cured product may not exhibit sufficient rubber elasticity.

[0086] Furthermore, the linear diorganopolysiloxane raw rubber of component (A) must have at least two alkenyl groups per molecule, and in the above formula (I), R 11 It is preferable that 0.001 to 10 mol %, particularly 0.01 to 5 mol % of the total is an alkenyl group. The alkenyl group is preferably a vinyl group or an allyl group, and particularly preferably a vinyl group.

[0087] The average degree of polymerization of the organopolysiloxane of component (A) is 100 or higher (usually 100 to 100,000), more preferably in the range of 1,000 to 100,000, even more preferably in the range of 3,000 to 50,000, and particularly preferably in the range of 4,000 to 20,000. If the average degree of polymerization is less than 100, the silicone rubber composition of the present invention will no longer satisfy the properties required for millable rubber, and roll kneading properties and the like will be significantly impaired, which is undesirable.

[0088] The average degree of polymerization is determined from the weight average molecular weight in terms of polystyrene in a GPC (gel permeation chromatography) analysis measured under the following conditions. (Measurement conditions) Developing solvent: toluene ·Flow rate: 1mL / min Detector: Refractive index detector (RI) Column: KF-805L x 2 (Shodex) Column temperature: 25℃ Sample injection volume: 30 μL (0.2% by mass toluene solution)

[0089] The linear diorganopolysiloxane raw rubber of component (A) is not particularly limited as long as it satisfies the conditions of alkenyl group and average degree of polymerization, but it is also preferable that the main chain contains diorganosiloxane units (R 11 2SiO 2 / 2 , R 11 is the same as above, and so on below), and both ends of the molecular chain are triorganosiloxy groups (R 11 3SiO 1 / 2 Preferably, the organopolysiloxane is a straight-chain diorganopolysiloxane gum terminated with a trimethylsiloxy group, a dimethylvinylsiloxy group, a dimethylhydroxysiloxy group, a methyldivinylsiloxy group, a trivinylsiloxy group, or the like, and more preferably, the molecular chain is terminated with a siloxy group having at least one vinyl group. These organopolysiloxanes may be used alone, or two or more types with different degrees of polymerization or molecular structures may be used in combination.

[0090] The content of component (A) in the composition of the present invention is preferably 43 to 96 mass %, more preferably 50 to 90 mass %, and even more preferably 50 to 80 mass %.

[0091] -(B) Organohydrogenpolysiloxane- Component (B) is an organohydrogenpolysiloxane having at least two, and preferably three or more, silicon-bonded hydrogen atoms (SiH groups) per molecule. Component (B) acts as a curing agent (crosslinking agent) for curing the one-component millable silicone rubber composition of the present invention, which cures (crosslinks) via a hydrosilylation addition reaction; the SiH groups in component (B) crosslink with the alkenyl groups in component (A) via a hydrosilylation addition reaction to cure the composition.

[0092] Component (B) may be a conventional organohydrogenpolysiloxane contained in an addition reaction curable organopolysiloxane composition, preferably one having at least two, preferably three or more, more preferably 3 to 100, and even more preferably 4 to 50 silicon-bonded hydrogen atoms (SiH groups) per molecule.

[0093] The SiH group content in the organohydrogenpolysiloxane is preferably 0.0005 to 0.02 mol / g, and particularly preferably 0.001 to 0.017 mol / g. If the amount of SiH groups is less than the lower limit, crosslinking may be insufficient. If the amount of SiH groups is more than the upper limit, volatility may be high, and some of the organohydrogenpolysiloxane may volatilize out of the composition during compounding, production, or product storage.

[0094] Preferably, the number of silicon atoms per molecule is 2 to 300, particularly 3 to 150, and particularly about 4 to 100, and the organohydrogenpolysiloxane is liquid at room temperature (23°C ± 15°C, hereinafter the same). The hydrogen atoms bonded to the silicon atoms may be located at either the terminals of the molecular chain, midway along the molecular chain (non-terminal), or both. The molecular structure of the organohydrogenpolysiloxane may be linear, cyclic, branched, or three-dimensional network.

[0095] (B) Organohydrogenpolysiloxane is represented, for example, by the following average composition formula (II): R 12 b H c SiO (4-b-c) / 2 (II)

[0096] In formula (II), R 12 are each independently a monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 8. b is a positive number of 0.7 to 2.1, c is a positive number of 0.001 to 1.0, and b+c is a positive number that satisfies the range of 0.8 to 3.0. The organohydrogenpolysiloxane contains silicon-bonded hydrogen atoms (SiH groups) in the above-mentioned amount, and preferably has the above-mentioned number of silicon atoms. In the above formula (II), R 12 The monovalent hydrocarbon group represented by the formula 11 Among them, groups having no aliphatic unsaturated bonds are preferred.

[0097] In the above formula (II), b is a positive number of 0.7 to 2.1, preferably 0.8 to 2.0, c is a positive number of 0.001 to 1.0, preferably 0.01 to 1.0, and b+c is 0.8 to 3.0, preferably 1.0 to 2.5.

[0098] (B) Organohydrogenpolysiloxanes include, for example, 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, tris(hydrogendimethylsiloxy)methylsilane, tris(hydrogendimethylsiloxy)phenylsilane, methylhydrogencyclopolysiloxane, methylhydrogensiloxane-dimethylsiloxane cyclic copolymer, methylhydrogenpolysiloxane capped at both ends with trimethylsiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymer capped at both ends with trimethylsiloxy groups, dimethylpolysiloxane capped at both ends with dimethylhydrogensiloxy groups, dimethylsiloxane capped at both ends with dimethylhydrogensiloxy groups, Siloxane-methylhydrogensiloxane copolymer, methylhydrogensiloxane-diphenylsiloxane copolymer endblocked with trimethylsiloxy groups at both ends, methylhydrogensiloxane-diphenylsiloxane-dimethylsiloxane copolymer endblocked with trimethylsiloxy groups at both ends, methylhydrogensiloxane-methylphenylsiloxane-dimethylsiloxane copolymer endblocked with trimethylsiloxy groups at both ends, methylhydrogensiloxane-dimethylsiloxane-diphenylsiloxane copolymer endblocked with dimethylhydrogensiloxy groups at both ends, methylhydrogensiloxane-dimethylsiloxane-methylphenylsiloxane copolymer endblocked with dimethylhydrogensiloxy groups at both ends, (CH3)2HSiO 1 / 2 Units and (CH3)3SiO 1 / 2 Units and SiO 4 / 2 A copolymer consisting of (CH3)2HSiO units 1 / 2 Units and SiO 4 / 2 A copolymer consisting of (CH3)2HSiO units 1 / 2 Units and SiO 4 / 2 Units and (C6H5)SiO 3 / 2 and copolymers consisting of these exemplified compounds in which some or all of the methyl groups have been substituted with other alkyl groups, phenyl groups, or the like.

[0099] Furthermore, the organohydrogenpolysiloxane (B) may be a polyvalent aromatic ring-containing organohydrogenpolysiloxane in which, in the compounds exemplified above, a part of the siloxane skeleton (-Si-O-Si-) that constitutes the molecule (usually at a part of the position of the oxygen atom that forms the siloxane bond) contains a typically divalent to tetravalent aromatic ring-containing hydrocarbon skeleton (for example, a phenylene skeleton, a bisphenylene skeleton, a bis(phenylene)ether skeleton, a bis(phenylene)methane skeleton, a 2,2-bis(phenylene)propane skeleton, a 2,2-bis(phenylene)hexafluoropropane skeleton, etc.).

[0100] The amount of component (B) blended is 0.01 to 50 parts by mass, preferably 0.1 to 30 parts by mass, per 100 parts by mass of component (A). Furthermore, the molar ratio (SiH groups / alkenyl groups) of silicon-bonded hydrogen atoms (SiH groups) in component (B) to the total number of silicon-bonded alkenyl groups in components (A) and (B) (particularly in component (A)) is preferably 0.6 to 10, particularly 1 to 5. If this ratio is less than 0.6, curing (crosslink density) may be insufficient, resulting in a sticky rubber. If it is more than 10, the resulting silicone rubber composition may foam during curing or may be difficult to release from a mold.

[0101] -(C) Reinforcing Silica- The reinforcing silica of component (C) acts as a filler that imparts excellent mechanical properties to the resulting silicone rubber composition. The reinforcing silica may be precipitated silica (wet silica) or fumed silica (fumed silica or dry silica). Typically, untreated reinforcing silica has numerous silanol (SiOH) groups on its surface. In the present invention, the specific surface area of ​​the reinforcing silica of component (C) measured by the BET method is 50 m 2 / g or more, and preferably 100 to 450m 2 / g, more preferably 100 to 300m 2 / g. This specific surface area is 50m 2 If it is less than 1 / g, the reinforcing effect of component (C) will be insufficient.

[0102] The reinforcing silica of component (C) may be used in an untreated state, or may be surface-treated (hydrophobized) with an organosilicon compound such as organopolysiloxane, organopolysilazane, chlorosilane, alkoxysilane, etc. These reinforcing silicas may be used alone or in combination of two or more. The reinforcing silica of component (C) can be a commercially available product, and examples thereof include the Aerosil series (manufactured by Nippon Aerosil Co., Ltd.), such as Aerosil 130, Aerosil 200, Aerosil 300, Aerosil R-812, Aerosil R-972, and Aerosil R-974; surface-untreated or surface-hydrophobized (i.e., hydrophilic or hydrophobic) fumed silica, such as Cabosil MS-5 and MS-7 (manufactured by Cabot Corporation), and Reolosil QS-102, 103, and MT-10 (manufactured by Tokuyama Corporation); and surface-untreated or surface-hydrophobized precipitated silica, such as Tokusil US-F (manufactured by Tokuyama Corporation), NIPSIL-SS, and NIPSIL-LP (manufactured by Nippon Silica Co., Ltd.).

[0103] The amount of reinforcing silica (C) blended is 5 to 100 parts by mass, preferably 10 to 80 parts by mass, and more preferably 20 to 70 parts by mass per 100 parts by mass of organopolysiloxane (A). If the blending amount is outside this range, not only will the processability of the resulting silicone rubber composition decrease, but the mechanical properties such as tensile strength and tear strength of the cured silicone rubber obtained by curing the silicone rubber composition will also be insufficient.

[0104] -(D) Platinum-phosphite complex-containing hydrosilylation catalyst - As the platinum-phosphite complex-containing hydrosilylation catalyst of component (D), the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention described above is used. The amount of platinum-phosphite complex-containing hydrosilylation catalyst (Component (D)) 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 Component (A). If the amount of platinum-phosphite complex-containing hydrosilylation catalyst is less than 0.001 part by mass, the strength of the resulting cured product may be reduced or the product may be poorly cured. Conversely, if the amount of platinum-phosphite complex-containing hydrosilylation catalyst is more than 10 parts by mass, the resulting composition may become discolored, the time required for curing may be shortened, and the product may be uneconomical. The activity of the catalyst, i.e., curability, can be controlled by increasing or decreasing the concentration of the platinum-phosphite complex-containing hydrosilylation catalyst. The acetylene alcohol contained in component (D) acts as a reaction inhibitor in the composition, making it possible to inhibit the curing of the millable silicone rubber composition at room temperature for an extended period of time.

[0105] -Other ingredients- In addition to the above components, the one-component millable silicone rubber composition of the present invention may optionally contain, within the scope of the effects of the present invention, dispersants (wetters) for fillers such as reinforcing silica (component (C)); reinforcing inorganic fillers other than component (C) such as calcium carbonate and fumed titanium dioxide; non-reinforcing inorganic fillers such as calcium silicate, titanium dioxide, ferric oxide, and carbon black; various fillers such as inorganic fillers with or without surface hydrophobic treatment, and organic resin balloons; silane coupling agents (for example, alkoxysilanes containing a monovalent hydrocarbon group having a functional group (e.g., an epoxy group, a (meth)acryloxy group, a mercapto group, etc.) containing a heteroatom selected from oxygen, nitrogen, and sulfur atoms); Optional ingredients that can be blended include adhesion promoters such as hydrolyzable organosilane compounds 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) in the molecule, such as dimethylpolysiloxane (dimethylsilicone oil) terminated at both molecular chain ends with trimethylsilyl groups, dimethylsiloxane-diphenylsiloxane copolymers terminated at both molecular chain ends with trimethylsilyl groups, and dimethylsiloxane-methylphenylsiloxane copolymers terminated at both molecular chain ends with trimethylsilyl groups (methylphenylsilicone oil), addition reaction regulators, and additives such as pigment paste and reinforcing silicone resins.

[0106] -Method of manufacturing the composition- The one-component millable silicone rubber composition of the present invention can be obtained by kneading the components that make up the composition under shear stress using a known kneader such as a kneader, Banbury mixer, twin-roll mill, etc. In this case, the remainder of component (A), if any, is added to a base compound containing some or all of the organopolysiloxane of component (A) and the reinforcing silica of component (C), along with the organohydrogenpolysiloxane of component (B), and the platinum-phosphite complex-containing hydrosilylation catalyst of component (D), and the mixture is kneaded using a kneader such as a twin-roll mill, thereby easily obtaining the desired one-component millable silicone rubber composition with excellent storage stability.

[0107] The curing conditions for the curable organopolysiloxane composition containing the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention must be such that the composition is cured by heating. The heating temperature is preferably in the range of 60 to 250°C, more preferably 80 to 150°C. There are no particular restrictions on the curing time, but a curing time of approximately 10 to 120 minutes is more preferred.

[0108] [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]

[0109] 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.

[0110] [Example 1] 0.3311 parts of tris(2,4-di-tert-butylphenyl)phosphite was weighed into a transparent glass container, and 9.6689 parts of n-hexane (boiling point: 68°C) was added. The container was then 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 platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex solution containing 1% Pt atoms (solvent: dimethylpolysiloxane with a degree of polymerization of 180 and capped at both ends with vinyldimethylsiloxy groups) was added. The container was then sealed and stirred for 30 minutes to obtain a uniform solution (preparation of a silicone solution containing a platinum-phosphite ester complex). Next, 2.50 parts of 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane was added, the flask was sealed, and the mixture was stirred for 60 minutes to achieve uniformity. 1.0 part of 3-methyltridec-1-yn-3-ol was then added to the solution, the flask was sealed, and the mixture was stirred for 60 minutes to achieve 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: 40°C x 2 hours / approximately 35 hPa). The 100 ml eggplant-shaped flask yielded 13.6 g of a pale yellow, transparent liquid (yield: 98.3%). This silicone solution of platinum-phosphite complex-containing hydrosilylation catalyst was designated "Catalyst I." (The amount of the phosphite compound was 1.0 mole per mole of platinum atom in the platinum catalyst, the amount of the vicinal alkenyl group-containing organopolysiloxane compound was 14.2 moles per mole of platinum atom in the platinum-phosphite complex, and the amount of acetylene alcohol was 9.3 moles per mole of platinum atom in the platinum-phosphite complex.)

[0111] [Example 2] 0.3311 parts of tris(2,4-di-tert-butylphenyl)phosphite was weighed into a transparent glass container, and 9.6689 parts of n-hexane 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 platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex solution containing 1% 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 obtain a uniform solution (preparation of silicone solution containing platinum-phosphite ester complex). Next, 2.5 parts of 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane was added, the flask was sealed, and the mixture was stirred for 60 minutes to achieve uniformity. 2.0 parts of 1-ethynyl-1-cyclohexanol was then added to the solution, the flask was sealed, and the mixture was stirred for 60 minutes to achieve 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: 40°C x 2 hours / approximately 32 hPa). The 100 ml eggplant-shaped flask yielded 14.8 g of a pale yellow, transparent liquid (yield: 99.8%). This silicone solution of platinum-phosphite complex-containing hydrosilylation catalyst was designated "Catalyst II." (The amount of the phosphite compound was 1.0 mole per mole of platinum atom in the platinum catalyst, the amount of the vicinal alkenyl group-containing organopolysiloxane compound was 14.2 moles per mole of platinum atom in the platinum-phosphite complex, and the amount of acetylene alcohol was 18.6 moles per mole of platinum atom in the platinum-phosphite complex.)

[0112] [Example 3] 0.3311 parts of tris(2,4-di-tert-butylphenyl)phosphite was weighed into a transparent glass container, and 9.6689 parts of n-hexane 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 platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex solution containing 1% 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 obtain a uniform solution (preparation of silicone solution containing platinum-phosphite ester complex). Next, 0.1765 parts of 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane was added, the flask was sealed, and the mixture was stirred for 60 minutes to achieve uniformity. 1.0 parts of 3-methyltridec-1-yn-3-ol was then added to the solution, the flask was sealed, and the mixture was stirred for 60 minutes to achieve 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: 40°C x 2 hours / approximately 32 hPa). The 100 ml eggplant-shaped flask yielded 11.47 g of a clear yellow liquid (yield: 99.7%). This silicone solution of platinum-phosphite complex-containing hydrosilylation catalyst was designated "Catalyst III." (The amount of the phosphite compound was 1.0 mole per mole of platinum atom in the platinum catalyst, the amount of the vicinal alkenyl group-containing organopolysiloxane compound was 1.0 mole per mole of platinum atom in the platinum-phosphite complex, and the amount of acetylene alcohol was 9.3 moles per mole of platinum atom in the platinum-phosphite complex.)

[0113] [Comparative Example 1] The same procedure as in Example 1 was repeated, except that 2.5 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, 13.7 g of a transparent yellow liquid was obtained in a 100 ml eggplant-shaped flask (yield: 99.1%). This silicone solution of a platinum-phosphite complex-containing hydrosilylation catalyst is designated "Catalyst IV." (The amount of the phosphite compound was 1.0 mole per mole of platinum atom in the platinum catalyst, the amount of the vicinal alkenyl group-containing organopolysiloxane compound was 0 mole per mole of platinum atom in the platinum-phosphite complex, and the amount of acetylene alcohol was 9.3 moles per mole of platinum atom in the platinum-phosphite complex.)

[0114] Comparative Example 2 The same procedure as in Example 1 was repeated, except that 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane was not used. As a result, 11.15 g of a transparent yellow liquid was obtained in a 100 ml eggplant-shaped flask (yield: 98.4%). This silicone solution of a platinum-phosphite complex-containing hydrosilylation catalyst was designated "Catalyst V." (The amount of the phosphite compound was 1.0 mole per mole of platinum atom in the platinum catalyst, the amount of the vicinal alkenyl group-containing organopolysiloxane compound was 0 mole per mole of platinum atom in the platinum-phosphite complex, and the amount of acetylene alcohol was 9.3 moles per mole of platinum atom in the platinum-phosphite complex.)

[0115] Comparative Example 3 The same procedure as in Example 1 was repeated, except that 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane and 3-methyltridec-1-yn-3-ol were not used. As a result, 10.33 g of a colorless, transparent liquid was obtained in a 100 ml recovery flask (yield: 99.9%). This silicone solution of a platinum-phosphite complex-containing hydrosilylation catalyst is designated "Catalyst VI." (The amount of the phosphite compound is 1.0 mole per mole of platinum atom in the platinum catalyst, the amount of the vicinal alkenyl group-containing organopolysiloxane compound is 0 mole per mole of platinum atom in the platinum-phosphite complex, and the amount of the acetylene alcohol is 0 mole per mole of platinum atom in the platinum-phosphite complex.)

[0116] Comparative Example 4 The same procedure as in Example 1 was carried out, but without using n-hexane. As a result, a brown, transparent liquid (yield: 13.8 g) with white crystals dispersed therein was obtained in a 100 ml eggplant-shaped flask; a colorless, transparent liquid was not obtained (yield: 99.8%). This silicone solution of a platinum-phosphite complex-containing hydrosilylation catalyst is designated "Catalyst VII." (The amount of the phosphite compound was 1.0 mole per mole of platinum atom in the platinum catalyst, the amount of the vicinal alkenyl group-containing organopolysiloxane compound was 14.2 moles per mole of platinum atom in the platinum-phosphite complex, and the amount of acetylene alcohol was 9.3 moles per mole of platinum atom in the platinum-phosphite complex.)

[0117] [test] The following appearance 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.

[0118] 〔exterior〕 The platinum-phosphite ester complex-containing hydrosilylation catalysts obtained in Examples 1 to 3 and Comparative Examples 1 to 4 were each stored in a sealed container filled with nitrogen. The appearance was then checked immediately after production (23°C), and after 3 days and 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.

[0119] [Table 1]

[0120] [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.

[0121] 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 to pale yellow, transparent liquids at 23°C, and it was confirmed that the liquids retained the same color tone even after 3 months at 23°C.

[0122] In contrast, the platinum-phosphite complex-containing hydrosilylation catalysts of Comparative Examples 1 to 3 did not contain an organopolysiloxane compound (vicinal alkenyl group-containing organopolysiloxane compound) having a unit represented by general formula (2), and therefore, although the platinum-phosphite complex-containing hydrosilylation catalyst was initially produced as a yellow, transparent liquid, it had poor long-term property stability, resulting in the precipitation of crystals over time. Furthermore, with 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.

[0123] As is clear from the above results, the present invention provides a stable, liquid platinum-phosphite complex-containing hydrosilylation catalyst. In Example 1, the structure of the Pt catalyst in each step of preparing the platinum-phosphite complex-containing hydrosilylation catalyst was 195The results were confirmed by Pt-NMR, and are shown in Table 2 and Figure 1.

[0124] [Table 2]

[0125] [evaluation] For the platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex containing Pt atoms, a single peak was observed near -6,130 ppm. However, when a phosphite ester compound was added, the peak shifted to approximately -5,600 ppm and -5,660 ppm and split. The change in peak position suggested that the platinum catalyst and the phosphite ester compound formed a complex. When a vicinal alkenyl-containing organopolysiloxane compound was added to this complex, multiple peaks appeared near -5,540 ppm to -5,700 ppm. These results suggest that the platinum-phosphite ester complex and the vicinal alkenyl-containing organopolysiloxane compound associate with each other. Furthermore, when acetylene alcohol was added to this association, numerous peaks were confirmed between approximately -5,540 ppm and approximately -5,700 ppm, but the results showed that the peaks clearly had different intensities than before the addition of acetylene alcohol. Therefore, it is presumed that the acetylene alcohol stabilizes the unstable structures in the association between the platinum-phosphite ester complex and the adjacent alkenyl group-containing organopolysiloxane compound, causing a change in peak intensity.

[0126] [Examples of Curable Organopolysiloxane Compositions Utilizing Platinum-Phosphite Complex-Containing Hydrosilylation Catalysts] In order to clarify the effect of the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention, the catalysts obtained in Examples 1 to 3 and Comparative Examples 1 to 4 above (stored in a sealed container at 23°C for 3 months) and examples and comparative examples relating to curable organopolysiloxane compositions using a general platinum catalyst will be described in more 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.

[0127] [Composition Example 1] 100 parts of dimethylpolysiloxane crude rubber (corresponding to n1 = 2.00 in the above formula (I)) consisting of 99.85 mol% dimethylsiloxane units, 0.125 mol% methylvinylsiloxane units, and 0.025 mol% dimethylvinylsiloxy units and having an average degree of polymerization of 6,000; 2 55 parts of fumed silica (Aerosil 200, manufactured by Nippon Aerosil Co., Ltd.) with a molecular weight of 1 / g, 12 parts of dimethyldimethoxysilane, 0.2 parts of vinyltrimethoxysilane, 12 parts of dimethylpolysiloxane having silanol groups at both ends, an average degree of polymerization of 4, and a viscosity of 15 mPa·s at 23°C, and 0.15 parts of 3% 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).

[0128] To 100 parts of dimethylpolysiloxane gum, 1.7 parts of an organohydrogenpolysiloxane represented by the following formula (hydrosilyl group amount: 0.00726 mol / g, corresponding to b = 1.5 and c = 0.05 in formula (II) above), 0.05 parts of "Catalyst I" prepared in Example 1, and 0.00080 parts of ethynylmethyldecylcarbinol were added to the base compound (1), and the mixture was mixed uniformly using a twin roll mill to produce a gum-like one-component millable curable organopolysiloxane composition I. [ka]

[0129] Composition Example 2 A one-component millable curable organopolysiloxane composition II was prepared in the same manner as in Example 1, except that 0.05 parts of "catalyst II" was used instead of "catalyst I".

[0130] Composition Example 3 A one-component millable curable organopolysiloxane composition III was prepared in the same manner as in Example 1, except that 0.05 parts of "catalyst III" was used in place of "catalyst I".

[0131] [Comparative Composition Example 1] A one-component millable curable organopolysiloxane composition IV was prepared in the same manner as in Example 1, except that 0.05 parts of "catalyst IV" was used in place of "catalyst I".

[0132] [Comparative Composition Example 2] A one-component millable curable organopolysiloxane composition V was prepared in the same manner as in Example 1, except that 0.05 parts of "catalyst V" was used in place of "catalyst I".

[0133] [Comparative Composition Example 3] A one-component millable curable organopolysiloxane composition VI was prepared in the same manner as in Example 1, except that 0.05 parts of "catalyst VI" was used in place of "catalyst I".

[0134] [Comparative Composition Example 4] A one-component millable curable organopolysiloxane composition VII was prepared in the same manner as in Example 1, except that 0.05 parts of "catalyst VII" was used in place of "catalyst I".

[0135] [Comparative Composition Example 5] One-component millable curable organopolysiloxane composition VIII was produced in the same manner as in Example 1, except that 0.05 parts of a platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex solution containing 1% 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."

[0136] [Comparative Composition Example 6] In Composition Example 1, instead of 0.05 parts of "Catalyst I," 0.046 parts of "Catalyst I'" was added, which was prepared in the same manner as in Example 1, except that 1.0 part of 3-methyltridec-1-yn-3-ol was not added during the catalyst production process of Example 1. The mixture was then uniformly mixed and dispersed using a two-roll mill in the same manner as in Composition Example 1, and 0.004 parts of 3-methyltridec-1-yn-3-ol was added, and the mixture was uniformly mixed and dispersed using a two-roll mill to produce one-component millable curable organopolysiloxane Composition IX.

[0137] [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 6. The results, along with a pass / fail rating for the appearance of the catalyst, are shown in Table 3.

[0138] [Workability when preparing one-component millable curable organopolysiloxane compositions (workability when adding catalyst)] When preparing the one-component millable curable organopolysiloxane compositions prepared in Composition Examples 1 to 3 and Comparative Composition Examples 1 to 6, those in which the platinum-phosphite complex-containing hydrosilylation catalyst was liquid at 23°C and no problems occurred when it was added were judged to pass. Conversely, those in which the platinum-phosphite complex and / or the phosphite compound in the platinum-phosphite complex-containing hydrosilylation catalyst crystallized and problems occurred in workability when it was added were judged to fail.

[0139] [Storage stability of one-component millable curable organopolysiloxane compositions] The storage stability of the one-component millable curable organopolysiloxane compositions prepared in Composition Examples 1 to 3 and Comparative Composition Examples 1 to 6 was evaluated by measuring the initial curability of the resulting one-component millable curable organopolysiloxane compositions and their curability after 6 and 12 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 up to 12 months at 23°C were judged to pass.

[0140] [Table 3] *1) Platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex solution containing 1% by mass of Pt atoms

[0141] [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 these catalysts were found to be easy to work with when the catalyst was added, and to cure in 10 minutes at 150°C even when stored for long periods at 23°C, demonstrating curability virtually unchanged from that at the time of production.

[0142] In contrast, the platinum-phosphite complex-containing hydrosilylation catalysts of Comparative Examples 1 to 3 failed the appearance evaluation of the catalyst itself because crystals precipitated after 3 months or 3 days at 23°C. Furthermore, they also failed in workability because it was necessary to add the required amount of catalyst while removing the crystalline components when adding the catalyst. Furthermore, the one-component millable curable organopolysiloxane compositions of Comparative Examples 1 to 3 that used these catalysts hardened to a rubbery state after 1 year of storage at 23°C, demonstrating poor storage stability. 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 had poor storage stability. Comparative Composition Example 5 is an example of a one-component millable curable organopolysiloxane composition in which a typical platinum catalyst (i.e., a platinum catalyst containing no hydrocarbon organic solvent, selected from one or more platinum-vinyl group-containing siloxane complexes formed from platinum chloride, chloroplatinic acid, or chloroplatinic acid salts and vinyl group-containing siloxanes) was used directly without complexing with a phosphite ester or associating with a siloxane compound. The one-component millable curable organopolysiloxane composition of Comparative Composition Example 5, produced using this catalyst, resulted in reduced storage stability. Comparative Composition Example 6 represents a case in which a platinum-phosphite complex-containing hydrosilylation catalyst of the present invention was used without the addition of acetylene alcohol. This comparative composition example 6 separately contained the same amounts of platinum-phosphite complex-containing hydrosilylation catalyst and acetylene alcohol as in Composition Example 1, and the components and blending amounts were the same as those in Composition Example 1. However, after storing the composition of Comparative Composition Example 6 at 23°C for 12 months (1 year), it hardened into a rubber-like state, indicating poor storage stability. Therefore, even when the same components and amounts were added, the composition of the present invention, which used a platinum-phosphite complex-containing hydrosilylation catalyst to which acetylene alcohol had been added in advance, demonstrated significantly superior storage stability.

[0143] 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]

[0144] The platinum-phosphite complex-containing hydrosilylation catalyst of the present invention, while previously characterized by the formation of crystals, can maintain its liquid state at 23°C without the use of hydrocarbon organic solvents. Therefore, the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention improves the stability of the hydrosilylation catalyst itself and improves the workability of producing curable organopolysiloxane compositions using this catalyst. Furthermore, the absence of hydrocarbon organic solvents makes it extremely safe from an industrial perspective, resulting in minimal adverse effects on the human body and a high level of robustness. Furthermore, curable organopolysiloxane compositions incorporating the platinum-phosphite complex-containing hydrosilylation catalyst of the present invention have excellent storage stability and can maintain stable properties and physical characteristics even when exposed to room temperature for extended periods of time. This makes 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) 【Chemistry 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 comprising a phosphite ester compound represented by the formula: 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. an alkenyl group-containing siloxane compound that is liquid at 23°C, the alkenyl group-containing siloxane compound containing an organopolysiloxane compound having a unit represented by the formula: Acetylenic alcohol with a melting point of 35°C or less The platinum-phosphite complex-containing hydrosilylation catalyst is liquid at 23°C and does not contain any hydrocarbon organic solvent.

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. 3. The platinum-phosphite complex-containing hydrosilylation catalyst according to claim 1, 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).

4. The platinum-phosphite ester complex-containing hydrosilylation catalyst according to any one of claims 1 to 3, wherein the alkenyl group-containing siloxane compound further comprises at least one compound selected from the group consisting of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane and a linear dimethylpolysiloxane capped at both molecular chain terminals with dimethylvinylsiloxy groups.

5. 5. The platinum-phosphite complex-containing hydrosilylation catalyst according to claim 1, wherein the acetylene alcohol has one ethynyl group and one hydroxy group in one molecule.

6. The platinum-phosphite ester complex-containing hydrosilylation catalyst according to claim 1, wherein the organopolysiloxane compound having units represented by the above formula (2) is composed solely of units represented by the above formula (2) except for the terminals of the molecular chain.

7. The platinum-phosphite complex-containing hydrosilylation catalyst according to claim 1, wherein n in formula (2) is an integer of 4 to 10.

8. A curable organopolysiloxane composition containing only the platinum-phosphite ester complex-containing hydrosilylation catalyst according to any one of claims 1 to 5 as a curing catalyst.

9. 9. The curable organopolysiloxane composition according to claim 8, which does not contain a hydrocarbon organic solvent.

10. An article comprising a cured product of the curable organopolysiloxane composition according to claim 8 or 9.

11. A method for producing a platinum-phosphite complex-containing hydrosilylation catalyst, comprising the following steps (a) to (e): (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; 【Transformation 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 product of a platinum-phosphite ester complex and an 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) adding an acetylene alcohol having a melting point of 35°C or less to the solution obtained in step (c); (e) A step of removing the hydrocarbon organic solvent having a boiling point of 80° C. or less from the solution obtained in the step (d).

12. The method for producing 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.

13. 13. The method for producing a platinum-phosphite complex-containing hydrosilylation catalyst according to claim 11, wherein 0.50 to 800 moles of acetylene alcohol are added per mole of platinum atom in the platinum-phosphite complex.

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