Addition-curable organopolysiloxane composition

Abstract

This addition-curable silicone composition contains: (A) a polysiloxane resin represented by formula (1) [where R1 is a monovalent hydrocarbon group not containing an aliphatic unsaturated bond, R2 is a hydrogen atom or an alkenyl group (the percentage of the number of hydrogen atoms in R2 is 10-90 mol%), R3 is a hydrogen atom or an alkyl group, and formula (1) is such that 0≤a≤0.6, 0.2≤b≤0.9, 0≤c≤0.8, 0≤d≤0.6, 0≤e≤0.8, 0≤f≤0.6, 0≤g≤0.8, 0.1≤(c+e+g)≤0.8, a+b+c+d+e+f+g=1, and 0≤h≤1 are satisfied]; (B) a straight-chain polysiloxane represented by formula (2) (where R4 is a monovalent hydrocarbon group not containing an aliphatic unsaturated bond, R5 is a hydrogen atom or an alkenyl group, R6 is a monovalent hydrocarbon group, and n is an integer from 0 to 1,200); and (C) a platinum group metal catalyst. The addition-curable silicone composition has an organosilsesquioxane unit and is excellent in flexibility and moldability.

Description

Addition-curable organopolysiloxane composition

[0001] The present invention relates to an addition-curable organopolysiloxane composition.

[0002] Conventionally, polysiloxanes that can be addition-crosslinked by hydrosilylation are known. However, it has been clarified by the studies of the present inventors that an addition-crosslinkable polysiloxane containing an alkylsilsesquioxane unit is difficult to synthesize because the hydrolysis-condensation reaction of its monomer, an alkyltrialkoxysilane compound, is very fast and gelation occurs.

[0003] Patent Document 1 discloses a method of performing hydrolysis by using a silanol group generated by hydrolysis of an alkoxysilyl group as a catalyst in order to slow down the rate of hydrolysis-condensation when hydrolyzing an alkoxysilane mixture containing methyltrimethoxysilane. Further, this document discloses a method of synthesizing an organopolysiloxane without gelation by adding a carboxylic acid or a carboxylate after performing hydrolysis-condensation and distilling off methanol. However, although the method of Patent Document 1 is suitable for the synthesis of low molecular weight organopolysiloxanes, since the polymerization is slow, severe reaction conditions are required to obtain a relatively high molecular weight organopolysiloxane, so the reaction control is difficult, and there are problems such as gelation, reduction in reproducibility, and deterioration in workability due to generation of microgels.

[0004] In order to solve these problems, Patent Document 2 discloses a method for efficiently producing an addition-crosslinkable polysiloxane having an alkylsilsesquioxane unit. However, the organopolysiloxane obtained by the formulation of Patent Document 2 has problems such as a hard cured film being obtained, but having no flexibility or softness and being inferior in moldability.

[0005] Japanese Patent No. 2712817 Japanese Unexamined Patent Application Publication No. 2020-111657

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide an addition-curable silicone composition having an organosilsesquioxane unit and excellent flexibility and moldability.

[0007] As a result of intensive studies to achieve the above object, the present inventors have found that a predetermined polysiloxane having an organosilsesquioxane unit and capable of addition crosslinking gives a cured product excellent in heat resistance and curability by heating, and is thus suitable as a binder component or a coating material such as a heat-resistant paint. They have also found that by blending a predetermined linear organopolysiloxane, flexibility and flexibility can be imparted to the polysiloxane and it can be easily molded, thereby completing the present invention.

[0008] That is, the present invention provides: 1. (A) A polysiloxane resin represented by the following formula (1): 100 parts by mass [In the formula, R 1 each independently represents a monovalent hydrocarbon group having 1 to 12 carbon atoms and not containing an aliphatic unsaturated bond, and R 2 each independently represents a hydrogen atom or an alkenyl group having 2 to 12 carbon atoms (however, the proportion of the number of hydrogen atoms among the total number of R 2 is 10 to 90 mol%), and R 3 each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and a, b, c, d, e, f and g satisfy 0 ≦ a ≦ 0.6, 0.2 ≦ b ≦ 0.9, 0 ≦ c ≦ 0.8, 0 ≦ d ≦ 0.6, 0 ≦ e ≦ 0.8, 0 ≦ f ≦ 0.6, 0 ≦ g ≦ 0.8, and 0.1 ≦ (c + e + g) ≦ 0.8 and a + b + c + d + e + f + g = 1, and h is a number satisfying 0 ≦ h ≦ 1.], (B) A linear polysiloxane represented by the following formula (2): 10 to 300 parts by mass, (In the formula, R 4 each independently represents a monovalent hydrocarbon group having 1 to 12 carbon atoms and not containing an aliphatic unsaturated bond, R 5 each independently represents a hydrogen atom or an alkenyl group having 2 to 12 carbon atoms, R 6 each independently represents a monovalent hydrocarbon group having 1 to 12 carbon atoms, and n is an integer of 0 to 1,200.) and (C) An addition-curable silicone composition containing a platinum group metal catalyst, 2. The R 1 is a methyl group or a phenyl group, and the R 21. An addition-curable silicone composition in which the alkenyl group is a vinyl group. 3. An addition-curable silicone composition in which a is 0. 4. An addition-curable silicone composition in which g is 0. 5. An addition-curable silicone composition in which c, e, and g are numbers satisfying 0 ≤ c ≤ 0.4, 0.1 ≤ e ≤ 0.5, 0 ≤ g ≤ 0.4, and 0.2 ≤ (c + e + g) ≤ 0.8. 6. An addition-curable silicone composition in which the alkenyl group content in component (A) is 0.05 to 0.6 mol / 100g. 7. An addition-curable silicone composition in which the weight-average molecular weight (Mw) of component (A) in terms of polystyrene in gel permeation chromatography is 1,000 to 50,000. 8. The present invention provides an addition-curable silicone composition in which the number of hydrogen atoms bonded to silicon atoms in the composition is 0.8 to 2.0 per alkenyl group bonded to silicon atoms in the composition, and a cured product of any of the addition-curable silicone compositions of 1 to 8.

[0009] The present invention provides a composition containing an addition-crosslinkable polysiloxane having organosilsesquioxane units, which, upon heating, yields a heat-resistant cured product. Therefore, it is suitable for use as a binder component in heat-resistant paints and resins, as well as for coatings on building materials and molded articles, and as a coating and sealing material for electronic components. Furthermore, the polysiloxane of the present invention exhibits excellent flexibility and pliability, making it easy to mold and process, and enabling its application in a wide range of uses.

[0010] The present invention will be described in detail below. [1] Addition-curable organopolysiloxane composition The addition-curable organopolysiloxane composition in the present invention contains (A) organopolysiloxane resin, (B) linear organopolysiloxane, and (C) platinum group metal catalyst.

[0011] [Component (A)] Component (A) is a polysiloxane resin represented by the following formula (1), and has an alkenyl group bonded to a silicon atom and a hydrogen atom (Si-H group) bonded to a silicon atom. It is a component that imparts hardness to the resulting cured product by forming crosslinks with other components (A) and / or with component (B), which will be described later, through a hydrosilylation reaction.

[0012]

[0013] In equation (1), R 1 Each of these independently represents a monovalent hydrocarbon group having 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms, and more preferably 1 to 6 carbon atoms, that does not contain an aliphatic unsaturated bond. 1 The monovalent hydrocarbon group having 1 to 12 carbon atoms can be linear, branched, or cyclic. Specific examples include linear or branched alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, i-butyl, tert-butyl, neopentyl, n-hexyl, n-heptyl, and n-octyl groups; cycloalkyl groups such as cyclopentyl and cyclohexyl groups; unsubstituted aryl groups such as phenyl and naphthyl groups; alkylaryl groups such as tolyl, xylyl, ethylphenyl, propylphenyl, and butylphenyl groups; and aralkyl groups such as benzyl and phenylethyl groups. Among these, R 1 The group is preferably a methyl group or a phenyl group, and particularly preferably a methyl group.

[0014] R 2 Each of these is independently a hydrogen atom or an alkenyl group having 2 to 12 carbon atoms. 2 The alkenyl group having 2 to 12 carbon atoms may be linear, branched, or cyclic. Specific examples include vinyl, 1-propenyl, allyl(2-propenyl), hexenyl, octenyl, cyclopentenyl, and cyclohexenyl groups, with vinyl being preferred among these. 2 The proportion of hydrogen atoms in the total number of atoms is 10 to 90 mol%, preferably 30 to 70 mol%. If the proportion of hydrogen atoms is less than 10 mol% or more than 90 mol%, curing failure may occur, and the hardness of the cured product may decrease significantly.

[0015] R 3 Each of these is independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. 3The alkyl group having 1 to 4 carbon atoms can be linear, branched, or cyclic, and specific examples include methyl, ethyl, n-propyl, isopropyl, n-butyl, i-butyl, tert-butyl, and among them R 3 Hydrogen atoms, methyl groups, and ethyl groups are preferred as the elements.

[0016] In equation (1), a is a number satisfying 0 ≤ a ≤ 0.6, but from the viewpoint of crack suppression effect, a number satisfying 0 ≤ a ≤ 0.3 is preferred, and 0 is more preferred. b is a number satisfying 0.2 ≤ b ≤ 0.9, but from the viewpoint of scratch resistance of the resulting cured product, a number satisfying 0.2 ≤ b ≤ 0.7 is preferred, and a number satisfying 0.3 ≤ b ≤ 0.6 is preferred. c is a number satisfying 0 ≤ c ≤ 0.7, but from the viewpoint of hardness and flexibility of the resulting cured product, a number satisfying 0.1 ≤ c ≤ 0.4 is preferred, and 0 is more preferred. d is a number satisfying 0 ≤ d ≤ 0.6, but from the viewpoint of hardness of the resulting cured product, a number satisfying 0 ≤ d ≤ 0.5 is preferred, and a number satisfying 0 ≤ d ≤ 0.4 is more preferred. e is a number satisfying 0 ≤ e ≤ 0.7, but from the viewpoint of hardness of the resulting cured product, a number satisfying 0.1 ≤ e ≤ 0.5 is preferred, and a number satisfying 0.1 ≤ e ≤ 0.3 is more preferred. f is a number that satisfies 0 ≤ f ≤ 0.6, but from the viewpoint of the heat stability and crack resistance of the resulting cured product, a number that satisfies 0.1 ≤ f ≤ 0.4 is preferred, and a number that satisfies 0.1 ≤ f ≤ 0.2 is more preferred. g is a number that satisfies 0 ≤ g ≤ 0.7, but from the viewpoint of the hardness of the resulting cured product and the stability of the composition, a number that satisfies 0 ≤ g ≤ 0.4 is preferred, and 0 is more preferred. a, b, c, d, e, f, and g are numbers that satisfy a + b + c + d + e + f + g = 1. Also, c + e + g is a number that satisfies 0.1 ≤ (c + e + g) ≤ 0.8, but a number that satisfies 0.1 ≤ (c + e + g) ≤ 0.5 is preferred, and a number that satisfies 0.1 ≤ (c + e + g) ≤ 0.3 is more preferred. h is a number satisfying 0 ≤ h ≤ 1, but from the viewpoint of the curability of the composition and the crack resistance of the resulting cured product, a number satisfying 0 ≤ h ≤ 0.2 is preferred, and a number satisfying 0 ≤ h ≤ 0.1 is more preferred.

[0017] (A) Specific examples of components include, but are not limited to, those listed below. Note that Me represents a methyl group, Ph represents a phenyl group, and Vi represents a vinyl group (the same applies below). (MeSiO 3 / 2 ) 0.5 (MeViSIO) 2 / 2 ) 0.15 (MeHSio 2 / 2 ) 0.15 (Me3SiO 1 / 2 ) 0.2 (HO 1 / 2 ) 0.02 (PhSiO 3 / 2 ) 0.5 (MeViSIO) 2 / 2 ) 0.15 (MeHSio 2 / 2 ) 0.15 (Me3SiO 1 / 2 ) 0.2 (HO 1 / 2 ) 0.02 (SiO 4 / 2 ) 0.1 (MeSiO 3 / 2 ) 0.43 (MeViSIO) 2 / 2 ) 0.15 (MeHSio 2 / 2 ) 0.15 (Me3SiO 1 / 2 ) 0.17 (HO 1 / 2 ) 0.02

[0018] (A) The alkenyl group content in component (A) is preferably 0.05 to 0.6 mol / 100g, and more preferably 0.1 to 0.3 mol / 100g, from the viewpoint of the curability of the composition. For example, the method used in the later examples can be used as the measurement conditions for the alkenyl group content.

[0019] The weight-average molecular weight (Mw) of the above organopolysiloxane in gel permeation chromatography (GPC), calculated in terms of polystyrene, is preferably 1,000 to 50,000, and more preferably 5,000 to 20,000. If the weight-average molecular weight is 1,000 or higher, it exhibits excellent film formation, storage stability, and coating properties, and if it is 50,000 or lower, there is no risk of unevenness or uneven coating during painting. For example, the measurement conditions for GPC can be the method used in the later examples.

[0020] Note that component (A) may be a single composition or a mixture of multiple polysiloxane resins with different compositions.

[0021] Component (A) can be produced by known methods. For example, it can be synthesized according to the procedure described in Japanese Patent Application Publication No. 2020-111657, and is obtained by hydrolyzing and condensing a chlorosilane and / or alkoxysilane, or a partially hydrolyzed condensate thereof, which can form siloxane units constituting the polysiloxane resin represented by formula (1) above by hydrolysis and condensation, in an organic solvent capable of dissolving the raw material silane compound and the resulting polysiloxane resin under acidic conditions. To obtain a polysiloxane with a desired weight-average molecular weight, this can be done by adjusting the monomer mixing ratio, reaction temperature and time, and the amounts of water and organic solvent used. The polysiloxane resin thus produced is then subjected to removal of organic solvents as needed, and precipitates are removed by filtration.

[0022] [Component (B)] Component (B) is a linear polysiloxane represented by the following formula (2), and is a component that forms crosslinks with the alkenyl groups and / or Si-H groups bonded to the silicon atoms of component (A) through a hydrosilylation reaction, thereby imparting flexibility to the cured product.

[0023]

[0024] In equation (2), R 4 Each of these is independently a monovalent hydrocarbon group having 1 to 12 carbon atoms, preferably 1 to 6 carbon atoms, and more preferably 1 to 3 carbon atoms, that does not contain an aliphatic unsaturated bond. 4The monovalent hydrocarbon group having 1 to 12 carbon atoms can be linear, branched, or cyclic. Specific examples include linear or branched alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, i-butyl, tert-butyl, neopentyl, n-hexyl, n-heptyl, and n-octyl groups; cycloalkyl groups such as cyclopentyl and cyclohexyl groups; aryl groups such as phenyl and naphthyl groups; alkylaryl groups such as tolyl, xylyl, ethylphenyl, propylphenyl, and butylphenyl groups; and aralkyl groups such as benzyl and phenylethyl groups. Preferably, the alkyl group has 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms, with the methyl group being particularly preferred.

[0025] R 5 Each of these is independently a hydrogen atom or an alkenyl group having 2 to 12 carbon atoms. 5 The alkenyl group having 2 to 12 carbon atoms can be linear, branched, or cyclic, and specific examples include vinyl, 1-propenyl, allyl(2-propenyl), hexenyl, octenyl, cyclopentenyl, and cyclohexenyl groups. Among these, R 5 A hydrogen atom or a vinyl group is preferred.

[0026] R 6 Each of these is independently a monovalent hydrocarbon group having 1 to 12 carbon atoms, preferably 1 to 6 carbon atoms, and more preferably 1 to 3 carbon atoms. 6 The monovalent hydrocarbon group having 1 to 12 carbon atoms can be linear, branched, or cyclic. Specific examples include linear or branched alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, i-butyl, tert-butyl, neopentyl, n-hexyl, n-heptyl, and n-octyl groups; cycloalkyl groups such as cyclopentyl and cyclohexyl groups; aryl groups such as phenyl and naphthyl groups; alkylaryl groups such as tolyl, xylyl, ethylphenyl, propylphenyl, and butylphenyl groups; aralkyl groups such as benzyl and phenylethyl groups; vinyl, 1-propenyl, allyl(2-propenyl), hexenyl, octenyl, cyclopentenyl, and cyclohexenyl groups. Among these, R6 A methyl group or a vinyl group is preferred.

[0027] n is an integer between 0 and 1,200, and is preferably an integer between 10 and 1,000, considering the balance between the hardness and flexibility of the cured product.

[0028] (B) Specific examples of component include, but are not limited to, those listed below. HMe2SiO-(Me2SiO) 10 -SiMe2H HMe2SiO- (Me2SiO) 20 -SiMe2H HMe2SiO- (Me2SiO) 40 -SiMe2H HMe2SiO- (Me2SiO) 400 -SiMe2H HMe2SiO- (Me2SiO) 1000 -SiMe2H ViMe2SiO- (Me2SiO) 10 -SiMe2Vi ViMe2SiO- (Me2SiO) 20 -SiMe2Vi ViMe2SiO- (Me2SiO) 40 -SiMe2Vi ViMe2SiO- (Me2SiO) 400 -SiMe2Vi ViMe2SiO- (Me2SiO) 1000 -SiMe2Vi Vi3SiO- (Me2SiO) 10 -SiVi3 Vi3SiO- (Me2SiO) 20 -SiVi3 Vi3SiO- (Me2SiO) 40 -SiVi3 Vi3SiO- (Me2SiO) 400 -SiVi3 Vi3SiO- (Me2SiO) 1000 -SiVi3

[0029] The amount of component (B) is in the range of 10 to 300 parts by mass, preferably 25 to 250 parts by mass, and more preferably 40 to 200 parts by mass, per 100 parts by mass of component (A). If the amount of component (B) is less than the lower limit, the flexibility may be poor, and if it exceeds the upper limit, the hardness may be insufficient. Component (B) may be used alone or in combination of two or more types.

[0030] From the viewpoint of the reactivity of the composition, the number of hydrogen atoms bonded to silicon atoms in the composition is preferably 0.8 to 2.0 per alkenyl group bonded to silicon atoms, and more preferably 1.0 to 1.7 per alkenyl group bonded to silicon atoms. Furthermore, the ratio of the number of hydrogen atoms bonded to silicon atoms to the alkenyl groups bonded to silicon atoms can be determined, for example, by the method used in later examples.

[0031] [Component (C)] Component (C) is a platinum group metal catalyst, and any platinum group metal catalyst that promotes the addition reaction (hydrosilylation reaction) of organopolysiloxanes is acceptable. Conventional and known platinum group metal catalysts used in hydrosilylation reactions can be used. Examples include platinum-based, palladium-based, and rhodium-based catalysts, but platinum-based catalysts, which are relatively easy to obtain, are preferred. Examples include elemental platinum, platinum black, chloroplatinic acid, chloroplatinic acid-olefin complex, chloroplatinic acid-divinyltetramethyldisiloxane complex, chloroplatinic acid-alcohol coordination compound, platinum diketone complex, platinum-olefin complex, platinum-alcohol complex, platinum coordination compound, etc. Note that a single platinum group metal catalyst may be used, or two or more may be used in combination.

[0032] The amount of component (C) should be an effective amount as a catalyst, that is, an effective amount necessary to promote the hydrosilylation reaction and cure the composition of the present invention. Preferably, it is 0.1 to 500 ppm, more preferably 1 to 300 ppm, on a mass basis converted to platinum group metal atoms relative to the mass of component (A). If the amount of catalyst is above the lower limit, the catalytic effect is reliably obtained, and if it is below the upper limit, the catalytic effect increases in proportion to the amount added, making it economical.

[0033] [Other Components] In addition to the components (A) to (C) above, the addition-curable silicone composition of the present invention may contain any other components as long as they do not impair the effects of the present invention. For example, the addition-curable silicone composition of the present invention may contain a reaction control agent that suppresses the progress of the hydrosilylation reaction in order to extend the shelf life and pot life. The reaction control agent may be a conventionally known reaction control agent used in addition-curable silicone compositions, and examples include acetylene compounds such as ethynylmethyldecylcarbinol, 1-ethynyl-1-cyclohexanol, and 3,5-dimethyl-1-hexyne-3-ol; various nitrogen compounds such as tributylamine, tetramethylethylenediamine, and benzotriazole; organophosphorus compounds such as triphenylphosphine; oxime compounds; and organochloro compounds.

[0034] When using a reaction control agent, the amount to be added is preferably 0.01 to 2.0 parts by mass, more preferably 0.01 to 0.1 parts by mass, per 100 parts by mass of component (A). Within this range, the reaction control effect is sufficiently exhibited. The reaction control agent may be diluted with organopolysiloxane, toluene, or the like to improve its dispersibility in the addition-curable silicone composition.

[0035] The addition-curable silicone composition of the present invention may contain a heat-resistant additive to improve heat resistance. Examples of heat-resistant additives include cerium oxide, iron oxide, halogen compounds, and hindered amine compounds. When a heat-resistant additive is used, the amount added is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, per 100 parts by mass of component (A).

[0036] The addition-curable silicone composition of the present invention may contain a diluent to reduce viscosity. The diluent is not particularly limited as long as it can dissolve or disperse the organopolysiloxane of the present invention, and specific examples include aromatic hydrocarbons such as toluene and xylene; hydrocarbons such as hexane and octane; ketones such as methyl ethyl ketone and methyl isobutyl ketone; esters such as ethyl acetate and isobutyl acetate; and alcohols such as methanol, ethanol, isopropanol, butanol, isobutanol, and t-butanol.

[0037] The addition-curable silicone composition of the present invention may contain an adhesion aid to impart adhesion to a substrate. Examples of adhesion aids include organosilicon compounds such as silanes and siloxanes containing functional groups that impart adhesion, and non-silicone organic compounds. Specific examples of functional groups that impart adhesion include vinyl groups bonded to silicon atoms, alkenyl groups such as allyl groups, epoxy groups bonded to silicon atoms via hydrogen atoms or carbon atoms (e.g., γ-glycidoxypropyl group, β-(3,4-epoxycyclohexyl)ethyl group, acryloxy groups (e.g., γ-acryloxypropyl group), methacryloxy groups (e.g., γ-methacryloxypropyl group), and alkoxysilyl groups (e.g., trimethoxysilyl groups, triethoxysilyl groups, methyldimethoxysilyl groups, and other alkoxysilyl groups bonded to silicon atoms via alkylene groups that may contain one or two ester, urethane, or ether structures).

[0038] Examples of organosilicon compounds containing functional groups that impart adhesion include silane coupling agents, siloxanes having alkoxysilyl groups and organic functional groups, and compounds obtained by introducing alkoxysilyl groups into organic compounds having reactive organic groups. Examples of non-silicone organic compounds include allyl esters of organic acids such as triallyl isocyanurate, epoxy ring-opening catalysts, organotitanium compounds, organozirconium compounds, and organoaluminum compounds. The adhesive aid may be used alone or in combination of two or more types.

[0039] When using an adhesive aid, the amount to be added is preferably 0.05 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, per 100 parts by mass of component (A).

[0040] The addition-curable silicone composition of the present invention may contain inorganic fillers to improve its reinforcing properties. Examples of inorganic fillers include fuzzy silica (dry silica), precipitated silica (wet silica), crystalline silica, polysilsesquioxane, titanium dioxide, alumina, and fillers obtained by surface hydrophobizing these fillers with organosilicon compounds such as organoalkoxysilane compounds, organochlorosilane compounds, organosilazane compounds, and low molecular weight siloxane compounds. When using inorganic fillers, the amount added is preferably 0.1 to 30 parts by mass, more preferably 1 to 15 parts by mass, per 100 parts by mass of component (A).

[0041] The addition-curable silicone composition of the present invention may contain organopolysiloxane raw rubber to improve its strength. Raw rubber refers to a high polymer that is either a very viscous liquid or a non-liquid (paste or solid) substance with no self-flow properties at room temperature (25°C). The average degree of polymerization of the organopolysiloxane raw rubber is preferably 2,000 to 50,000, and more preferably 2,500 to 30,000. Examples of organopolysiloxane raw rubber include dimethylpolysiloxane, methylphenylpolysiloxane, methylvinylpolysiloxane, methylphenylsiloxane / dimethylsiloxane copolymer, methylvinylsiloxane / dimethylsiloxane copolymer, and methylphenylsiloxane / methylvinylsiloxane / dimethylsiloxane copolymer, in which both ends of the molecular chain are sealed with trimethylsiloxy groups, dimethylphenylsiloxane groups, vinyldimethylsiloxane groups, divinylmethylsiloxane groups, trivinylsiloxy groups, methylphenylvinylsiloxane groups, etc. When using organopolysiloxane raw rubber, the amount blended is preferably 0.1 to 30 parts by mass, more preferably 1 to 15 parts by mass, per 100 parts by mass of component (A).

[0042] There are no particular limitations on the method for preparing the addition-curable silicone composition of the present invention; the components (A) to (C) described above and any other components as needed can be mixed by appropriate means.

[0043] [2] Cured Products The addition-curable silicone composition of the present invention can be cured to form a cured product. The curing conditions are not particularly limited, but it is preferable to use a temperature of 100 to 250°C for 30 to 300 minutes. The cured products of the present invention have an excellent balance of heat resistance, hardness, and flexibility, and can therefore be suitably used as binder components for heat-resistant paints and heat-resistant resins, as well as for coatings on building materials and molded articles, and as coating and sealing materials for electronic components.

[0044] The present invention will be described in more detail below with reference to synthesis examples, examples, and comparative examples, but the present invention is not limited to the following examples. The average composition of organopolysiloxanes was determined using an NMR measuring device manufactured by JEOL Ltd. 1 H-NMR and 29 These values ​​are calculated from the integrated values ​​of the Si-NMR spectrum, and similarly, the amount of alkenyl groups in the composition and the ratio of the number of hydrogen atoms bonded to silicon atoms to the alkenyl groups bonded to silicon atoms in the composition are also calculated. 1 The weight-average molecular weight (Mw) was calculated from 1H-NMR. The weight-average molecular weight is the polystyrene equivalent value obtained by GPC (gel permeation chromatography) measurement under the following conditions. [GPC conditions] Apparatus: HLC-8220 (manufactured by Tosoh Corporation) Columns: TSKgel GMHXL-L, TSKgel G4000HXL, TSKgel G2000HXL ×2 Developing solvent: Tetrahydrofuran (THF) Flow rate: 1 mL / min Detector: RI Column oven temperature: 40°C Standard substance: Polystyrene

[0045] [1] Synthesis of organopolysiloxane resins [Synthesis Example 1] 4,086.6 g of methyltrimethoxysilane was placed in a glass flask equipped with a stirrer, thermometer, condenser, and dropping device. Then, 486 g of 1N hydrochloric acid was added dropwise over 1 hour while stirring, and the mixture was reacted at 67°C for 2 hours. The resulting solution was neutralized with 29.2 g of propylene oxide, and polysilsesquioxane (A-0) was obtained by distilling off volatile components and solvent. 2,252 g of the obtained polysilsesquioxane (A-0), 1,090 g of vinylmethyldimethoxysilane, 876 g of methyldimethoxysilane, 1,292 g of hexamethyldisiloxane, and 4,137 g of toluene were mixed with 60 g of methanesulfonic acid while stirring. Then, 539 g of water was added dropwise over 1 hour, and the mixture was reacted at 67°C for 2 hours, and then at a temperature range of 80-90°C for 3 hours. The obtained solution was washed with water until the aqueous solution of the extract became neutral, and then the solvent was removed by distillation to obtain the product. The proportions of each constituent unit in equation (1) calculated from the NMR measurement results of the obtained organopolysiloxane resin (A-1) were a=0, b=0.5, c=0, d=0, e=0.3, f=0.2, g=0, and h=0.02, respectively. 1 R is a methyl group, 2 The vinyl group:hydrogen atom = 50:50 (molar ratio), R 3 The hydrogen atom was present, with a weight-average molecular weight of 10,000 and an alkenyl group content of 0.2 moles / 100g.

[0046] [Synthesis Example 2] Organopolysiloxane resin (A-2) was synthesized using the same method as in Synthesis Example 1, except that polysilsesquioxane (A-0) was replaced with 1,3-diphenyl-1,1,3,3-tetramethoxydisiloxane in the same amount as in Synthesis Example 1 in terms of silicon atoms. The proportions of each constituent unit in equation (1) calculated from the NMR measurement results of the obtained organopolysiloxane resin (A-2) were a=0, b=0.5, c=0, d=0, e=0.3, f=0.2, g=0, h=0.02, and R 1 The ratio of methyl group to phenyl group is 9:5 (molar ratio), and R 2 The vinyl group:hydrogen atom = 50:50 (molar ratio), R 3is a hydrogen atom, having a weight average molecular weight of 8,000 and an alkenyl group content of 0.2 mol / 100 g.

[0047] [2] Preparation of addition-curable silicone compositions [Examples 1-1 to 1-7, Comparative Examples 1-1 to 1-3] Each of the components shown below was mixed at 25°C in the blending amounts (parts by mass) in Table 1 to prepare an addition-curable silicone composition. Further, the ratio (H / Vi) of the number of hydrogen atoms bonded to silicon atoms to the number of alkenyl groups bonded to silicon atoms in each composition was calculated from the results of NMR measurement.

[0048] Component (A) (A-1): Organopolysiloxane resin obtained in Synthesis Example 1 (A-2): Organopolysiloxane resin obtained in Synthesis Example 2 Component (B) (B-1): In the above formula (2), R 4 = methyl group, R 5 = hydrogen atom, R 6 = methyl group, linear polysiloxane represented by n = 20 (B-2): In the above formula (2), R 4 = methyl group, R 5 = hydrogen atom, R 6 = methyl group, linear polysiloxane represented by n = 40 (B-3): In the above formula (2), R 4 = methyl group, R 5 = hydrogen atom, R 6 = methyl group, linear polysiloxane represented by n = 10 (B-4): In the above formula (2), R 4 = methyl group, R 5 = vinyl group, R 6 = vinyl group, linear polysiloxane represented by n = 1000 Component (C) (C-1): Toluene solution of platinum-divinyltetramethyldisiloxane complex (platinum concentration 0.5% by mass) Other components inhibitor: ethynylmethyldecylcarbinol

[0049]

[0050] [3] Preparation and Evaluation of Cured Products The compositions obtained in Examples 1-1 to 1-8 and Comparative Examples 1-1 to 1-3 were added to Teflon® Petri dishes, heated at 200°C for 2 hours, and then allowed to cool to 25°C to produce cured products with a thickness of 0.3 mm. The moldability, hardness, and tensile elongation at break of the obtained cured products were measured. The results are shown in Table 2.

[0051] (1) When removing the hardened film formed in the moldable petri dish, samples with significant cracks were evaluated as ×, and samples that could be removed as a single film without cracks or other abnormalities were evaluated as ○. (2) Hardness Hardness was measured using a durometer type A in accordance with ASTM D2240. Samples with a score of less than A50 were evaluated as ×, and samples with a score of A50 or higher were evaluated as ○. (3) Tensile elongation at fracture Tensile elongation at fracture was calculated as a percentage of the initial state (100%) when a 1cm x 1cm test piece was taken and a load was applied diagonally until fracture. Samples with an elongation of 5% or more were evaluated as ○.

[0052]

[0053] As shown in Table 2, the addition-curing silicone compositions used in Examples 2-1 to 2-8 exhibited an excellent balance of moldability, hardness, and tensile elongation, as well as good workability. On the other hand, Comparative Example 2-1 lacked sufficient component (B), resulting in poor moldability; Comparative Example 2-2 had no problems with moldability, but lacked sufficient component (B), leading to poor tensile elongation at break; and Comparative Example 2-3 had an excess of component (B), resulting in insufficient hardness.

Claims

1. (A) Polysiloxane resin represented by the following formula (1): 100 parts by mass [In the formula, R 1 Each of these independently represents a monovalent hydrocarbon group having 1 to 12 carbon atoms that does not contain an aliphatic unsaturated bond, R 2 Each of these independently represents a hydrogen atom or an alkenyl group having 2 to 12 carbon atoms (however, R 2 The proportion of hydrogen atoms in the total number of atoms is 10-90 mol%, R 3 Each of these independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and a, b, c, d, e, f, and g are numbers satisfying 0 ≤ a ≤ 0.6, 0.2 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.8, 0 ≤ d ≤ 0.6, 0 ≤ e ≤ 0.8, 0 ≤ f ≤ 0.6, 0 ≤ g ≤ 0.8, and 0.1 ≤ (c + e + g) ≤ 0.8 and a + b + c + d + e + f + g = 1, and h is a number satisfying 0 ≤ h ≤ 1. ] (B) Linear polysiloxane represented by the following formula (2): 10 to 300 parts by mass, (In the formula, R 4 Each of these independently represents a monovalent hydrocarbon group having 1 to 12 carbon atoms that does not contain an aliphatic unsaturated bond, R 5 Each of these independently represents a hydrogen atom or an alkenyl group with 2 to 12 carbon atoms, R 6 Each of these independently represents a monovalent hydrocarbon group having 1 to 12 carbon atoms, and n is an integer from 0 to 1,200.) and (C) an addition-curable silicone composition containing a platinum group metal catalyst.

2. The R 1 is a methyl group or a phenyl group, and the alkenyl group in the R 2 is a vinyl group. The addition-curable silicone composition according to claim 1.

3. The addition-curable silicone composition according to claim 1, wherein a is 0.

4. The addition-curable silicone composition according to claim 1, wherein g is 0.

5. The addition-curable silicone composition according to claim 1, wherein c, e, and g are numbers satisfying 0 ≤ c ≤ 0.4, 0.1 ≤ e ≤ 0.5, 0 ≤ g ≤ 0.4, and 0.2 ≤ (c + e + g) ≤ 0.

8.

6. The addition-curable silicone composition according to claim 1, wherein the alkenyl group content in component (A) is 0.05 to 0.6 mol / 100g.

7. The addition-curable silicone composition according to claim 1, wherein the weight-average molecular weight (Mw) of component (A) in terms of polystyrene, as measured by gel permeation chromatography, is 1,000 to 50,000.

8. The addition-curable silicone composition according to claim 1, wherein the number of hydrogen atoms bonded to silicon atoms in the composition is 0.8 to 2.0 per alkenyl group bonded to silicon atoms in the composition.

9. A cured product of an addition-curable silicone composition according to any one of claims 1 to 8.

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