Curable silicone composition and cured product thereof

Abstract

This invention relates to a curable polysiloxane composition comprising: (A) a diorganopolysiloxane having two silanized alkenyl groups at the ends of two molecular chains; (B) an organopolysiloxane having silanized alkenyl groups; (C) an organopolysiloxane having silanized hydrogen atoms, and substantially composed of (c1) a diorganopolysiloxane having silanized hydrogen atoms at the ends of two molecular chains and (c2) an organopolysiloxane resin having silanized hydrogen atoms; and (D) a hydrosilylation catalyst. The composition can be cured to form a cured product exhibiting excellent adhesion properties to various substrates used in optical devices.

Description

Technical Field

[0001] The present invention relates to a curable polysilicone composition and its cured product. Prior Art

[0002] The curable polysilicone composition can be cured to form a cured product having high transparency and high elongation, allowing it to be used as an adhesive or a pressure-sensitive adhesive to improve the visibility of optical displays.

[0003] For example, Patent Document 1 discloses a curable polysiloxane composition comprising: at least one organopolysiloxane having at least two alkenyl groups in its molecule, at least one organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms in its molecule, and a hydrosilylation reaction catalyst.

[0004] Meanwhile, Patent Document 2 discloses a curable polysiloxane composition comprising: a linear or partially branched organopolysiloxane having an alkenyl group in its molecule, a resinous organopolysiloxane having an alkenyl group in its molecule, a linear or partially branched organohydrogenpolysiloxane having a silicon-bonded hydrogen atom at the end of the molecular chain, a resinous organohydrogenpolysiloxane having a silicon-bonded hydrogen atom in its molecule, and a hydrosilylation reaction catalyst.

[0005] However, a problem with these curable silicone compositions in forming cured products is that they exhibit poor adhesion properties to various substrates used in optical displays. Prior Art Documents Patent documents

[0006] Patent Document 1: U.S. Patent Application Publication No. 2014 / 0150972 A1 Patent Document 2: U.S. Patent Application Publication No. 2022 / 0002493 A1 Summary of the Invention

[0007] Technical issues

[0008] The present invention aims to provide a curable polysilicone composition capable of forming a cured product exhibiting excellent adhesion properties for various substrates used in optical displays; and further to provide a cured product exhibiting excellent adhesion properties. Solution to the problem

[0009] The curable polysilicone composition of the present invention comprises: (A) Diorganopolysiloxane, which is represented by the following general formula: R 1 2R 2SiO(R 1 2SiO) mSiR 1 2R 2 wherein each R 1 is independently an alkyl group having 1 to 12 carbon atoms, each R 2 is independently an alkenyl group having 2 to 12 carbon atoms, and "m" is an integer from 100 to 1000; (B) a resinous organopolysiloxane represented by the following average unit formula; (R 1 3SiO 1 / 2) a(R 2R 1 2SiO 1 / 2) b(SiO 4 / 2) c(HO 1 / 2) d wherein R1 and R2 are as described above, and "a", "b", "c", and "d" are values ​​satisfying the following conditions: a ≥ 0, b > 0, 0.3 ≤ c ≤ 0.7, 0 ≤ d ≤ 0.05, and a + b + c = 1, and the amount thereof is 1.0 to 5.0 parts by mass relative to 100 parts by mass of component (A); (C) an organopolysiloxane having silicon-bonded hydrogen atoms in an amount such that the molar ratio of silicon-bonded hydrogen atoms provided by component (C) relative to 1 mol of alkenyl groups provided by components (A) and (B) is in the range of 0.5 to 2; and (D) an effective amount of a hydrosilylation catalyst, Wherein component (C) is an organopolysiloxane consisting essentially of the following components (c1) and (c2): (c1) a diorganopolysiloxane having silicon-bonded hydrogen atoms at both molecular chain ends, and (c2) a resinous organopolysiloxane represented by the following average unit formula: (R 1 3SiO 1 / 2) e(HR 1 2SiO 1 / 2) f(SiO 4 / 2) g(HO 1 / 2) h Wherein R1 is as described above, and "e", "f", "g" and "h" are values ​​that satisfy the following conditions: e ≥ 0, f > 0, 0.3 ≤ g ≤ 0.7, 0 ≤ h ≤ 0.05, and e + f + g = 1, and The molar ratio of silicon-bonded hydrogen atoms provided by component (c1) to silicon-bonded hydrogen atoms provided by component (c2) is in the range of 10 to 60.

[0010] In various embodiments, the curable polysilicon composition may further include: (E) a hydrosilylation inhibitor in an amount of about 0.00001 to about 0.5 parts by mass relative to 100 parts by mass of the total mass of components (A) to (C).

[0011] The cured product of the present invention is obtained by curing the above-mentioned curable polysilicone composition. Effects of the Invention

[0012] The curable polysilicone composition of the present invention can be cured to form a cured product that exhibits excellent adhesion properties to various substrates used in optical displays. The cured product of the present invention exhibits excellent adhesion properties. definition

[0013] The terms "comprising" and "comprise" are used herein in their broadest sense to mean and encompass the concepts of "including," "consisting essentially of," and "consisting of." The use of "for example," "e.g.," "such as," and "including" to list illustrative examples is not limited to the examples listed. Thus, "for example" or "such as" means "for example, but not limited to" or "such as, but not limited to," and encompasses similar or equivalent examples. The term "about" is used herein to reasonably encompass or describe minor variations in values ​​measured by instrumental analysis or due to sample processing. These minor variations may be within approximately ±0 to 25%, ±0 to 10%, ±0 to 5%, or ±0 to 2.5% of a numerical value. Furthermore, the term "about," when used in conjunction with a range of values, applies to both values ​​within the range. Furthermore, the term "about" may apply to a numerical value even when not expressly stated.

[0014] Generally, as used herein, a hyphen "-" or a dash "–" means "to" or "up to" in a range of values; ">" means "higher than" or "greater than"; "≥" means "at least" or "greater than or equal to"; "<" means "lower than" or "less than"; and "≤" means "at most" or "less than or equal to." Each of the aforementioned patent applications, patents, and / or patent application publications is expressly incorporated herein by reference in its entirety, on a case-by-case basis, in one or more non-limiting embodiments. Simple diagram description

[0015] none Implementation Method

[0016] <Curable Polysilicone Composition>

[0017] First, the curable polysilicone composition of the present invention will be described in detail. <Component (A)>

[0018] Component (A) is an organopolysiloxane represented by the following general formula: R 1 2R 2SiO(R 1 2SiO) mSiR 1 2R 2.

[0019] In the above formula, each R 1 is independently an alkyl group having 1 to 12 carbon atoms. Examples of the alkyl group include methyl, ethyl, propyl, butyl and octyl, with methyl being preferred.

[0020] In the above formula, each R2 is independently an alkenyl group having 2 to 12 carbon atoms. Examples of alkenyl groups include vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, and dodecenyl, with vinyl being preferred.

[0021] In the above formula, "m" is an integer from 100 to 1000, alternatively an integer of 100 or 800. This is because when "m" is greater than or equal to the lower limit of the above range, the mechanical properties of the resulting cured product are sufficient, and when it is less than or equal to the upper limit of the above range, the resulting composition has a viscosity suitable for processing and handling.

[0022] The viscosity of component (A) at 25°C is not limited, but is generally in the range of about 100 mPa·s to about 100,000 mPa·s, alternatively in the range of about 200 mPa·s to about 50,000 mPa·s, and alternatively in the range of about 300 mPa·s to about 50,000 mPa·s. Note that in this specification, viscosity is a value measured at 23±2°C using a B-type viscometer in accordance with ASTM D 1084.

[0023] Component (B) is an organopolysiloxane resin represented by the following average unit formula: (R 1 3SiO 1 / 2) a(R 2R 1 2SiO 1 / 2) b(SiO 4 / 2) c(HO 1 / 2) d.

[0024] In the above formula, R 1 and R 2 are as described above. Examples thereof include the same groups as described above.

[0025] In the above formula, “a”, “b”, “c” and “d” are values ​​that satisfy the following conditions: a ≥ 0, b > 0, 0.3 ≤ c ≤ 0.7, 0 ≤ d ≤ 0.05, and a + b + c = 1, alternatively, 0.1 ≤ a ≤ 0.5, 0.01 ≤ b ≤ 0.2, 0.4 ≤ c ≤ 0.7, 0 ≤ d ≤ 0.05, and a + b + c = 1, or alternatively, 0.2 ≤ a ≤ 0.5, 0.01 ≤ b ≤ 0.2, 0.4 ≤ c ≤ 0.7, 0 ≤ d ≤ 0.05, and a + b + c = 1. This is because if "a", "b", "c" and "d" are values ​​within the above-mentioned ranges, the cured product obtained by curing the composition will have appropriate hardness and mechanical strength.

[0026] The amount of component (B) is in the range of 1.0 to 5.0 parts by mass, or alternatively, 1.0 to 3.0 parts by mass, relative to 100 parts by mass of component (A). This is because when the amount is greater than or equal to the lower limit of the above range, the mechanical properties of the resulting cured product are sufficient, while when it is less than or equal to the upper limit of the above range, the resulting composition has a viscosity suitable for processing and handling. <Component (C)>

[0027] Component (C) is a crosslinker for components (A) and (B) in the present composition and is an organopolysiloxane having silicon-bonded hydrogen atoms and is essentially composed of the following components (c1) and (c2): (c1) a diorganopolysiloxane having silicon-bonded hydrogen atoms at both molecular chain ends, and (c2) Resinous organopolysiloxanes represented by the following average unit formula: (R₁₃SiO₁₂)₄₄( ... Wherein R1 is as described above, and "e", "f", "g" and "h" are values ​​that satisfy the following conditions: e ≥ 0, f > 0, 0.3 ≤ g ≤ 0.7, 0 ≤ h ≤ 0.05, and e + f + g = 1.

[0028] Component (c1) acts as a chain extender in the hydrosilylation reaction with components (A) and (B) and improves the flexibility of the cured product. Examples of groups other than hydrogen atoms bonded to silicon atoms in component (C) include alkyl groups having 1 to 12 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, and the like; aryl groups having 6 to 20 carbon atoms, such as phenyl, tolyl, xylyl, and the like; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, phenethyl, and the like; and halogen-substituted alkyl groups having 1 to 12 carbon atoms, such as 3-chloropropyl, 3,3,3-trifluoropropyl, and the like. Methyl groups are preferred from the perspectives of economic efficiency and heat resistance.

[0029] Examples of such component (c1) include dimethylpolysiloxane terminated at both molecular chain terminals with dimethylhydrogensiloxy groups, copolymers of dimethylsiloxane terminated at both molecular chain terminals with dimethylhydrogensiloxy groups and methylphenylsiloxane, and mixtures of two or more types thereof.

[0030] Component (c2) acts as a crosslinking agent in the hydrosilylation reaction with components (A) and (B) and improves the mechanical properties of the cured product.

[0031] In the formula of component (c2), each R 1 is independently an alkyl group having 1 to 12 carbon atoms. Examples of the alkyl group are as mentioned above. Among them, a methyl group is preferred from the perspectives of economic efficiency and heat resistance.

[0032] In the formula of component (c2), "e", "f", "g" and "h" are values ​​that satisfy the following conditions: e ≥ 0, f > 0, 0.3 ≤ g ≤ 0.7, 0 ≤ h ≤ 0.05, and e + f + g = 1, alternatively 0 ≤ e ≤ 0.3, 0.1 ≤ f ≤ 0.7, 0.3 ≤ g ≤ 0.6, 0 ≤ h ≤ 0.05, and e + f + g = 1, or alternatively 0 ≤ e ≤ 0.1, 0.3 ≤ f ≤ 0.7, 0.3 ≤ g ≤ 0.6, 0 ≤ h ≤ 0.01, and e + f + g = 1. This is because if "e", "f", "g" and "h" are values ​​within the above-mentioned ranges, the cured product obtained by curing the composition will have appropriate hardness and mechanical strength.

[0033] The molar ratio of silicon-bonded hydrogen atoms provided by component (c1) to silicon-bonded hydrogen atoms provided by component (c2) is in the range of 10 to 60. This is because when the molar ratio is greater than or equal to the lower limit of the above range, the modulus of the obtained cured product is sufficient, while when it is less than or equal to the upper limit of the above range, the mechanical properties of the obtained cured product are sufficient.

[0034] The amount of component (C) is such that the molar ratio of silicon-bonded hydrogen atoms provided by component (C) to 1 mol of alkenyl groups provided by components (A) and (B) is in the range of 0.5 to 2, alternatively in the range of 0.8 to 2, or alternatively in the range of 0.5 to 1.5. This is because if the amount is greater than or equal to the lower limit of the above range, the resulting composition will be sufficiently cured. However, if the amount is less than or equal to the upper limit of the above range, the mechanical properties of the resulting cured product will be enhanced. <Component (D)>

[0035] Component (D) is a hydrosilylation catalyst used to promote the curing of the present composition. Examples include platinum-based catalysts, rhodium-based catalysts, and palladium-based catalysts, with platinum-based catalysts being preferred. Examples of platinum-based catalysts include finely divided platinum powder, platinum black, finely divided platinum-supported silica powder, platinum-supported activated carbon, chloroplatinic acid, alcoholic solutions of chloroplatinic acid, platinum-olefin complexes, and platinum-alkenylsiloxane complexes.

[0036] The amount of component (D) is an effective amount for promoting the curing of the present composition, and specifically, an amount in which the platinum atoms in the catalyst are in the range of about 0.1 to about 1,000 ppm, alternatively, in the range of about 1 to about 500 ppm, based on the mass unit of the present composition. This is because when the content of component (D) is greater than or equal to the lower limit of the above range, the curing of the resulting composition progresses, while when the content is less than or equal to the upper limit of the above range, the resulting product becomes less likely to discolor. <Component (E)>

[0037] The present composition may also contain (E) a hydrosilylation inhibitor to control its crosslinking reaction. Examples of component (E) include alkynols such as 1-ethynylcyclohexan-1-ol, 2-methyl-3-butyn-2-ol, 3,5-dimethyl-1-hexyn-3-ol, and 2-phenyl-3-butyn-2-ol; enyne compounds such as 3-methyl-3-pentene-1-yne and 3,5-dimethyl-3-hexene-1-yne; methylalkenylsiloxane oligomers such as 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane and 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane; alkynyloxysilanes such as dimethylbis(3-methyl-1-butyn-3-oxy)silane and methylvinylbis(1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane); (3-methyl-1-butyn-3-oxy)silane; alkynyloxysilane compounds such as methyltris(1-methyl-1-phenyl-propynyloxy)silane, dimethylbis(1-methyl-1-phenyl-propynyloxy)silane, methyltris(1,1-dimethyl-propynyloxy)silane, dimethylbis(1,1-dimethyl-propynyloxy)silane; triazoles, phosphines, thiols, hydrazines, sulfoxides, phosphates, nitriles, hydroperoxides, amines, ethylenically unsaturated isocyanates, fumarates (e.g., dialkyl fumarates, dienyl fumarates, and / or dialkoxyalkyl fumarates), maleates (e.g., diallyl maleate), olefins, and combinations thereof.

[0038] The amount of component (E) is not limited, and from the perspective of providing a sufficient pot life to the present composition, it is generally in the range of about 0.00001 to about 0.5 parts by mass, alternatively in the range of about 0.0001 to about 0.5 parts by mass, or alternatively in the range of about 0.0001 to about 0.1 parts by mass, relative to 100 parts by mass of the total mass of components (A) to (C). This is because when the amount of component (E) is greater than or equal to the lower limit of the above range, the pot life of the present composition is sufficient for use, and when the content is less than or equal to the upper limit of the above range, the curability of the present composition is suitable for use. <Other components>

[0039] The composition may contain an adhesion promoter, an antioxidant, a reactive diluent, a leveling agent, a filler, an antistatic agent, a defoaming agent, a pigment, or the like, within the scope not impairing the purpose of the present invention. <Cured Product>

[0040] Next, the cured product of the present invention will be described in detail.

[0041] A cured product can be obtained by curing the aforementioned curable silicone composition. The hardness of the cured product is not limited, but it generally has a 1 / 4 cone penetration of 20 to 90, as measured using a penetrometer specified in ASTM D1403. This is because when the penetration is greater than or equal to the lower limit of the aforementioned range, the cured product exhibits good peel strength, while when it is less than or equal to the upper limit of the aforementioned range, the cured product exhibits good mechanical properties.

[0042] Although the shape of the cured product is not limited, examples thereof include sheets, films, tapes, and blocks. In addition, it can be integrated with various types of substrates. Examples

[0043] The curable polysiloxane composition and cured product of the present invention will be described in further detail below using practical and comparative examples. However, the present invention is not limited to the following examples. Note that in the formula, Me and Vi represent methyl and vinyl groups, respectively. The viscosity of the organopolysiloxane was measured as follows. <Viscosity>

[0044] The viscosity at 23 ± 2°C was measured using a B-type viscometer (Brookfield HADVIII rotational viscometer, RV-03, 10 rpm, 2 min) according to ASTM D 1084 “Standard Test Methods for Viscosity of Adhesives.” <Penetration>

[0045] The curable silicone composition having a thickness of 10 mm or more was statically cured in an aluminum pan at 120° C. for 40 minutes, and the 1 / 4 cone penetration at 25° C. was measured using an Anton Paar penetrometer PNR 12 manufactured by Anton Paar GmbH. <180° Peel Strength>

[0046] A curable silicone composition having a thickness of 1 mm and a width of 25 mm was placed between a glass sheet and a PET film for 30 minutes at 60° C. and then post-cured for 3 days at 25° C. The 180° peel strength was measured at a peel speed of 305 mm / min. <Cohesive failure>

[0047] After measuring the 180° peel strength, the cured product exhibited cohesive failure to the glass sheet and the PET film. <Haze and Transmittance>

[0048] A curable silicone composition having a thickness of 1 mm was statically cured on a glass slide at 70° C. for 40 minutes, and then post-cured at 25° C. for 3 days. The haze and transmittance of the cured product at 25° C. were measured using a spectrophotometer CM-5 manufactured by Konica Minolta. <Haze and transmittance after high temperature / high humidity testing>

[0049] The cured product on the glass sheet was subjected to 85°C / 85% RH conditions for 3 days and then cooled. After the high temperature / high humidity test, the haze and transmittance of the cured product at 25°C were measured using a Konica Minolta CM-5 spectrophotometer. <Examples 1 to 6 and Comparative Examples 1 to 3>

[0050] The curable silicone composition shown in Table 1 was prepared using the components mentioned below. First, components (A), (B), and (D) were homogeneously mixed. Next, components (C) and (E) were added to produce the curable silicone composition. The resulting cured product was evaluated as described above. The results are shown in Table 1. The "SiH / Vi Ratio" in Table 1 indicates the molar ratio of silicon-bonded hydrogen atoms provided by component (C) relative to the vinyl groups provided by components (A) and (B). Furthermore, the "SiH Ratio" in Table 1 indicates the molar ratio of silicon-bonded hydrogen atoms provided by component (c1) relative to the silicon-bonded hydrogen atoms provided by component (c2).

[0051] The following components were used as component (A).

[0052] Component (a-1): dimethyl polysiloxane having a vinyl content of 0.21% by mass and The viscosity is 2400 mPa·s and is expressed by the following formula: ViMe 2SiO(Me 2SiO) 290SiMe 2Vi Component (a-2): dimethyl polysiloxane having a vinyl content of 0.14% by mass and The viscosity is 9600 mPa·s and is expressed by the following formula: ViMe 2SiO(Me 2SiO) 522SiMe 2Vi The following components were used as component (B).

[0053] Component (b-1): an organopolysiloxane resin having a vinyl content of 1.8% by mass and represented by the following average unit formula: (Me 3SiO 1 / 2) 0.39 (ViMe 2SiO 1 / 2) 0.05 (SiO 4 / 2) 0.56

[0054] The following components were used as component (C).

[0055] Component (c-1): dimethylpolysiloxane having a silicon-bonded hydrogen atom content of 0.14 mass % and represented by the following formula: HMe 2SiO(Me 2SiO) 20SiMe 2H Component (c-2): a resinous organopolysiloxane having a silicon-bonded hydrogen atom content

[0056] 1.0 mass % and is represented by the following average unit formula: (HMe 2SiO 1 / 2) 0.63(SiO 4 / 2) 0.37

[0057] The following components were used as component (D). Component (e-1): a solution of Pt-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex in 1,3-divinyl-1,1,3,3-tetramethyldisiloxane (the Pt content in the solution is 0.9% by mass)

[0058] The following components were used as component (E). Component (e-1): A mixture containing 3% by mass of 1-ethynylcyclohexan-1-ol and 97% by mass of dimethylpolysiloxane having a vinyl content of 0.21% by mass, having a viscosity of 430 mPa·s, and represented by the following formula: ViMe 2SiO(Me 2SiO) 179SiMe 2Vi Implementation Examples 1 2 3 4 5 Curable silicone composition (parts by mass) (A) (a-1) 62.59 57.59 63.25 63.75 62.61 (a-2) 30.00 35.00 30.00 30.00 30.00 (B) (b-1) 2.17 2.17 1.55 1.55 2.17 (C) (c-1) 5.00 5.00 5.00 4.50 5.00 (c-2) 0.045 0.045 0.045 0.045 0.035 (D) (d-1) 0.045 0.045 0.045 0.045 0.045 (E) (e-1) 0.015 0.015 0.015 0.015 0.015 SiH / Vi ratio 0.91 0.93 0.97 0.88 0.89 SiH ratio 15.6 15.6 15.6 14.0 28.0 Cured product penetrate 48 30 42 73 56 180° peeling strength (N) 23.5 23.3 29.0 11.3 9.6 Cohesive failure on glass (%) 100 100 100 100 100 Cohesive failure on PET (%) 100 100 100 100 100 Haze 0.07 0.07 0.07 0.07 0.07 initial After 85℃ / 85%RH 0.15 0.15 0.15 0.15 0.15 Transmittance (%) 99.7 99.7 99.7 99.7 99.7 initial After 85℃ / 85%RH 99.9 99.9 99.9 99.9 99.9 <Table 1 (continued)> Implementation Examples Comparative Example 6 1 2 3 Curable silicone composition (parts by mass) (A) (a-1) 62.12 59.77 62.56 61.60 (a-2) 30.00 30.00 30.00 30.00 (B) (b-1) 2.17 0.62 2.17 3.10 (C) (c-1) 5.50 4.50 5.00 5.00 (c-2) 0.015 0.0075 0.075 0.045 (D) (d-1) 0.045 0.045 0.045 0.045 (E) (e-1) 0.015 0.015 0.015 0.015 SiH / Vi ratio 0.97 0.92 0.94 0.83 SiH ratio 51.3 84.0 9.3 15.6 Cured product penetrate 35 97 28 60 180° peel strength (N) 25.4 0 28.5 10.6 Cohesive failure on glass (%) 100 0 100 10 Cohesive failure on PET (%) 100 0 33 100 Haze initial 0.07 0.07 0.07 0.07 After 85℃ / 85%RH 0.15 0.15 0.15 0.15 Transmittance (%) 99.7 99.7 99.7 99.7 initial After 85℃ / 85%RH 99.9 99.9 99.9 99.9 Industrial applicability

[0059] The curable polysilicone composition of the present invention has excellent curability and, upon curing, forms a cured product exhibiting excellent adhesive properties even under high temperature and high humidity conditions. Therefore, the curable polysilicone composition can be used as an adhesive and pressure-sensitive adhesive for display devices such as optical displays and the like (including touch panels) and optical semiconductor devices (including micro-LEDs).

Claims

1. A curable polysiloxane composition comprising: (A) a diorganopolysiloxane, represented by the following general formula: R12R2SiO(R12SiO)mSiR12R2 where each R1 is independently an alkyl group having 1 to 12 carbon atoms, each R2 is independently an alkenyl group having 2 to 12 carbon atoms, and "m" is an integer from 100 to 1000; (B) a resinous organopolysiloxane, represented by the average unit formula: (R13SiO1 / 2)a(R2R12SiO1 / 2)b(SiO4 / 2)c(H2O1 / 2)d where R1 and R2 are as described above, and "a", "b", "c" and "d" are values ​​satisfying the following conditions: a ≥ 0, b > 0, 0.3 ≤ c ≤ 0.7, 0 ≤ d ≤ 0.05, and a + b + c = 1, the amount of which is 1.0 to 5.0 parts by mass relative to 100 parts by mass of component (A); (C) an organopolysiloxane having silicon-bonded hydrogen atoms, the amount of which is such that the molar ratio of silicon-bonded hydrogen atoms provided by component (C) to 1 mol of alkenyl groups provided by components (A) and (B) is in the range of 0.5 to 2; and (D) an effective amount of a hydrosilylation catalyst, wherein component (C) is an organopolysiloxane consisting essentially of the following components (c1) and (c2): (c1) a diorganopolysiloxane having silicon-bonded hydrogen atoms at the ends of two molecular chains, and (c2) a resinous organopolysiloxane, which is represented by the following average unit formula: (R 13SiO 1 / 2) e(HR 12SiO 1 / 2) f(SiO₄ / 2) g(HO₁ / 2) h where R₁ is as described above, and "e", "f", "g", and "h" are values ​​satisfying the following conditions: e ≥ 0, f > 0, 0.3 ≤ g ≤ 0.7, 0 ≤ h ≤ 0.05, and e + f + g = 1, and where, The molar ratio of silicon-bonded hydrogen atoms provided by component (c1) to silicon-bonded hydrogen atoms provided by component (c2) is in the range of 10 to 60.

2. The curable polysiloxane composition of claim 1 further comprises: (E) a silane hydrocracking reaction inhibitor, in an amount of about 0.00001 to about 0.5 parts by mass relative to the total mass of 100 parts by mass of components (A) to (C).

3. A cured product obtained by curing a curable polysiloxane composition as claimed in claims 1 to 2.