Addition-curing silicone adhesive composition

Abstract

The present invention is an addition-curable silicone sealant composition comprising the following components: (A) a linear organopolysiloxane with an average degree of polymerization of 480 or more and containing at least two alkenyl groups bonded to silicon atoms in one molecule; (B) an alkenyl-containing silicone resin represented by the following general formula (1), (R13SiO1 / 2)a(R12SiO2 / 2)b(R1SiO3 / 2)c(SiO4 / 2)d (1); (C) a linear organohydrogen polysiloxane represented by the following general formula (2); and (D) an addition reaction catalyst, the total mass of which relative to the composition in platinum group metals (mass conversion) is 0.1 to 10 ppm; wherein the mass ratio of the aforementioned component (A) to the aforementioned component (B) in the addition-curable silicone sealant composition is (A) / (B) = 40 / 60 to 60 / 40. This provides an addition-curing silicone resin composition that imparts a cured product with excellent mold release properties and high transparency.

Description

[Technical Field]

[0001] This invention relates to an addition-curing silicone adhesive composition. [Previous Technology]

[0002] In order to improve the weather resistance of LED lights and various LCD screens and optical waveguides, high hardness and high transparency of silicone resins have attracted attention. Among them, an addition-curing silicone resin has been used. It is completely free of silicon dioxide and highly transparent. It does not lose its elasticity at low temperatures and is easier to form by thermosetting (Patent Documents 1-6).

[0003] Generally, silicone sealants used as optical waveguides for LED lights, etc., are required to have a high hardness (Japanese Industrial Standard JIS K 6253, type A hardness tester) of 65 or higher. The molding method for such silicone sealants involves first performing a single vulcanization using a mold, followed by a second vulcanization using a high-temperature dryer (oven) to stabilize the physical properties or remove volatile components from the hardened material. However, when using high-hardness silicone sealants that do not contain reinforcing silica, the hardened material has low tensile strength after being removed from the mold following the first molding, which can lead to defects or cracks in the hardened material. [Prior Art Documents] (Patent Documents)

[0004] Patent Document 1: Japanese Patent Application Publication No. 2006-335857. Patent Document 2: Japanese Patent Application Publication No. 2008-101056. Patent Document 3: Japanese Patent Application Publication No. 2010-174233. Patent Document 4: Japanese Patent Application Publication No. 2010-174234. Patent Document 5: WO2016 / 098883. Patent Document 6: WO2016 / 098884. [Summary of the Invention]

[0005] [Problem to be Solved by the Invention] The present invention is made to improve upon the above-mentioned situation, and its object is to provide an addition-curing silicone resin composition that imparts a cured product with excellent mold removal properties and high transparency. [Technical Means for Solving the Problem]

[0006] To solve the above problems, the present invention provides an addition-curing silicone adhesive composition comprising the following components: (A) a linear organopolysiloxane having an average degree of polymerization of 480 or more and containing at least two alkenyl groups bonded to silicon atoms in one molecule; (B) an alkenyl-containing silicone resin represented by the following general formula (1), (R1 3SiO1 / 2)a(R1 2SiO2 / 2)b(R1SiO3 / 2)c(SiO4 / 2)d (1) In general formula (1), R1 is an independent monovalent hydrocarbon group selected from alkyl groups having 1 to 10 carbon atoms and alkenyl groups having 2 to 10 carbon atoms, having an average of 2.5 or more alkenyl groups in one molecule, and 0 < a ≦ 0.7, 0 ≦ b ≦ 0.2, 0 ≦ c ≦ 0.2, 0 < d ≦ 0.7, wherein is a number that is 0.8 ≦ a + d ≦ 1 and a + b + c + d = 1; (C) A linear organohydrogen polysiloxane represented by the following general formula (2), in general formula (2), R2 is an independent alkyl group having 1 to 10 carbon atoms, R3 is an independent alkyl group having 1 to 10 carbon atoms or a hydrogen atom, e is an integer of 8 or more, f is an integer of 0 to 100, e / (e + f) is 40 mol% or more and the number of silicon atoms bonded to hydroxyl groups in one molecule is 10 or more; and, (D) Addition reaction catalyst, which has a total mass of 0.1 to 10 ppm relative to the composition in terms of platinum group metals (mass conversion); In this addition-curing silicone rubber composition, the mass ratio of the aforementioned component (A) to the aforementioned component (B) is (A) / (B) = 40 / 60 to 60 / 40, the mole ratio of the total Si-H groups to the total alkenyl groups in the composition (Si-H groups / total alkenyl groups) is 1.0 to 1.5, and in the sulfurization test using a torsional vibration type conical mold sulfurization tester (B-2 method) as described in Japanese Industrial Standard JIS K 6300-2:2001, when the 10% curing time measured at 150°C for 5 minutes is set as T10, and the 90% curing time is set as T90, T90-T10 is 160 seconds or more.

[0007] Any addition-curing silicone adhesive composition of the present invention can impart a cured material with excellent removability from the mold and high transparency.

[0008] Furthermore, it is preferable that the alkenyl content of the aforementioned component (A) is less than 0.00006 mol / g.

[0009] As long as it is such an addition-curing silicone rubber composition, the tensile strength of the rubber after one vulcanization will be better.

[0010] Furthermore, it is preferable that the alkenyl content of the aforementioned component (B) is 0.0006 to 0.001 mol / g.

[0011] As long as it is an addition-curing silicone rubber composition, the hardness of the cured product and the tensile strength during cutting after a single vulcanization will be better. [Effects of the Invention]

[0012] According to the present invention, an addition-curing silicone rubber composition can be obtained, wherein the hardness (A-type curing tester) after primary vulcanization is less than 55, the elongation at cutting is more than 300%, and the hardness after secondary vulcanization is more than 65, thereby giving the cured material excellent removal from the mold and high transparency.

Implementation Method

[0013] As mentioned above, the aim is still to develop an addition-curing silicone adhesive composition that can impart a cured product with excellent removability from the mold and high transparency.

[0014] As a result of the inventors’ research efforts to achieve the above-mentioned objectives, the following insights were discovered, which led to the completion of the present invention: by using an appropriate ratio of a relatively long-chain alkenyl linear organic polysiloxane, a specific alkenyl silicone resin, and an organic hydrosiloxane with a specific structure, and by adjusting the composition to increase the difference between the 10% curing time and the 90% curing time in the vulcanization test, a silicone adhesive composition can be obtained, which can set the hardness of the cured material after one vulcanization to 55 or less, and the elongation at cutting time to 300% or more. Furthermore, by a second vulcanization, the hardness can be increased to the target hardness (e.g., 65 or more), and a highly transparent cured material can be obtained.

[0015] The above insights were obtained when investigating various materials and discovering the following phenomenon: if the hardness (type A hardness tester) of the hardened material after one sulfurization is below 55 and the stretching during cutting is above 300%, it is easy to remove it from the mold.

[0016] That is, the present invention is an addition-curing silicone adhesive composition comprising the following components: (A) a linear organopolysiloxane having an average degree of polymerization of 480 or more and containing at least two alkenyl groups bonded to silicon atoms in one molecule; (B) an alkenyl-containing silicone resin represented by the following general formula (1), (R1 3SiO1 / 2)a(R1 2SiO2 / 2)b(R1SiO3 / 2)c(SiO4 / 2)d (1) In general formula (1), R1 is an independent monovalent hydrocarbon group selected from alkyl groups having 1 to 10 carbon atoms and alkenyl groups having 2 to 10 carbon atoms, having an average of 2.5 or more alkenyl groups in one molecule, and 0 < a ≦ 0.7, 0 ≦ b ≦ 0.2, 0 ≦ c ≦ 0.2, 0 < d ≦ 0.7, wherein is a number that is 0.8 ≦ a + d ≦ 1 and a + b + c + d = 1; (C) A linear organohydrogen polysiloxane represented by the following general formula (2), in general formula (2), R2 is an independent alkyl group having 1 to 10 carbon atoms, R3 is an independent alkyl group having 1 to 10 carbon atoms or a hydrogen atom, e is an integer of 8 or more, f is an integer of 0 to 100, e / (e + f) is 40 mol% or more and the number of silicon atoms bonded to hydroxyl groups in one molecule is 10 or more; and, (D) Addition reaction catalyst, which has a total mass of 0.1 to 10 ppm relative to the composition in terms of platinum group metals (mass conversion); In this addition-curing silicone rubber composition, the mass ratio of the aforementioned component (A) to the aforementioned component (B) is (A) / (B) = 40 / 60 to 60 / 40, the mole ratio of the total Si-H groups to the total alkenyl groups in the composition (Si-H groups / total alkenyl groups) is 1.0 to 1.5, and in the sulfurization test using a torsional vibration type conical mold sulfurization tester (B-2 method) as described in Japanese Industrial Standard JIS K 6300-2:2001, when the 10% curing time measured at 150°C for 5 minutes is set as T10, and the 90% curing time is set as T90, T90-T10 is 160 seconds or more.

[0017] The present invention will now be described in detail, but it is not limited thereto.

[0018] <Addition-curing silicone sealant composition> The addition-curing silicone sealant composition of the present invention is characterized by comprising the following components (A) to (D). Preferably, the addition-curing silicone sealant composition is in liquid form.

[0019] (A) An organopolysiloxane containing alkenyl linear chain organopolysiloxane (A) component is an organopolysiloxane containing alkenyl linear chain organopolysiloxane, wherein one molecule has at least 2 alkenyl groups bonded to silicon atoms and the average degree of polymerization is 480 or more.

[0020] The component (A) is suitable and can be represented by the following general formula (3). In general formula (3), R4 is a monovalent hydrocarbon group selected from alkyl groups having 1 to 10 carbon atoms and alkenyl groups having 2 to 10 carbon atoms, and g is an integer of 500 or more, generally 500 to 10,000, preferably an integer of 500 to 8,000.

[0021] Examples of monovalent hydrocarbon groups represented by R4 include: alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, and cyclohexyl; and alkenyl groups such as vinyl, allyl, butenyl, pentenyl, hexenyl, and cyclohexenyl. Methyl is preferred as R4, but the molecule must contain at least two alkenyl groups. Vinyl is preferred as the alkenyl group.

[0022] Examples of the aforementioned alkenyl-containing linear organopolysiloxanes include: dimethylvinylsiloxy-terminated dimethylpolysiloxanes, dimethylvinylsiloxy-terminated dimethylsiloxane-methylvinylsiloxane copolymers, trimethylsiloxy-terminated dimethylsiloxane-methylvinylsiloxane copolymers, trivinylsiloxy-terminated dimethylpolysiloxanes, and trivinylsiloxy-terminated dimethylsiloxane-methylvinylsiloxane copolymers. These components may be used individually or in combination of two or more.

[0023] The average degree of polymerization of the organopolysiloxane must be above 480, generally 480 to 10000, preferably 500 to 8000. A degree less than 480 will result in lower tensile strength of the rubber after single vulcanization. Furthermore, the so-called average degree of polymerization mentioned in this invention refers to the quantitative average degree of polymerization, specifically the average degree of polymerization measured by gel permeation chromatography (GPC) using polystyrene as a standard. [Measurement Conditions] Developing solvent: toluene. Flow rate: 1 mL / min. Detector: Differential refractive index detector (RI). Column: KF-805L×2 (Shodex Corporation). Column temperature: 25°C. Sample injection volume: 30 μL (0.2% by mass toluene solution).

[0024] Furthermore, the amount of alkenyl groups bonded to silicon atoms in the organopolysiloxane (alkenyl content) must be below 0.00006 mol / g, generally 0.00006 to 0.000003 mol / g, preferably 0.00006 to 0.000006 mol / g, and even more preferably 0.00006 to 0.00001 mol / g. As long as it is below 0.00006 mol / g, the tensile strength of the rubber after one vulcanization will not decrease.

[0025] As component (A), any linear organopolysiloxane containing an alkenyl group can be used with one or more molecular structures (e.g., the type or ratio of substituents of the three organosiloxy groups at the end of the molecular chain or the two organosiloxane units of the main chain) or different degrees of polymerization.

[0026] (B) The alkenyl-containing silicone resin (B) is a silicone resin composed of constituent units selected from R1 3SiO1 / 2 units (M units), R1 2SiO2 / 2 units (D units), R1SiO3 / 2 units (T units) and SiO4 / 2 units (Q units), and the silicone resin is represented by the following general formula (1). (R1 3SiO1 / 2)a(R1 2SiO2 / 2)b(R1SiO3 / 2)c(SiO4 / 2)d (1)

[0027] In general formula (1), R1 is an independent monovalent hydrocarbon group selected from alkyl groups having 1 to 10 carbon atoms and alkenyl groups having 2 to 10 carbon atoms. As a specific example, the same group as R4 shown in the aforementioned general formula (3) can be exemplified, and an average of 2.5 alkenyl groups are present in one molecule, preferably 2.5 to 5. When the number of alkenyl groups in one molecule is less than an average of 2.5, the hardened material is more viscous, and processing becomes difficult. Furthermore, from the viewpoint of the compatibility of component (B) with other components, vinyl groups are preferred as alkenyl groups, and 80 moles or more of R1 groups are preferred as methyl groups. If the compatibility of each component deteriorates, there is a concern that the transparency of the hardened material of the addition-curing silicone sealant composition will decrease. Furthermore, a is 0 < a ≦ 0.7, preferably 0.3 < a < 0.7; b is 0 ≦ b ≦ 0.2, preferably 0 ≦ b ≦ 0.1; c is 0 ≦ c ≦ 0.2, preferably 0 ≦ c ≦ 0.1; d is 0 < d ≦ 0.7, preferably 0.3 < d < 0.7, and becomes a + b + c + d = 1.

[0028] In the silicone resin (general formula (1)) of component (B) above, among the above four constituent units, M unit and Q unit are essential. In order to improve the hardness of the cured product of the addition-curing silicone resin composition, the proportion of these two constituent units in the total constituent units must be 80 mol% or more (0.8 ≦a+d ≦1.0), preferably 90 mol% or more (0.9 ≦a+d ≦1.0), and more preferably 100 mol% (a+d=1.0). Furthermore, D unit and T unit may or may not be included. As long as the molar ratio (a / d) of M unit to Q unit is 0.5 or more, the compatibility of component (B) with other components will not deteriorate, and as long as it is 1.5 or less, there will be no concern about the hardness of the cured product of the addition-curing silicone resin composition decreasing. Therefore, the molar ratio (a / d) between the M unit and the Q unit is preferably in the range of 0.5 to 1.5, and more preferably in the range of 0.7 to 1.2.

[0029] The alkenyl content (alkenyl amount) of the above-mentioned component (B) is preferably 0.0006 to 0.001 mol / g, more preferably 0.0007 to 0.001 mol / g. As long as the alkenyl content is above 0.0006 mol / g, it will not become a hardened material with excessively low hardness, and as long as it is below 0.001 mol / g, the tensile strength during cutting after a single sulfurization will not decrease.

[0030] Specific examples of the silicone resin for component (B) include: copolymers of vinyl dimethylsiloxy and Q units, copolymers of vinyl dimethylsiloxy-trimethylsiloxy and Q units, copolymers of vinyl dimethylsiloxy-dimethylsiloxy and Q units, and copolymers of trimethylsiloxy-vinylmethylsiloxy and Q units. One of these components may be used alone, or two or more may be used in combination.

[0031] (C) Organohydrogen polysiloxane (C) component is a linear organohydrogen polysiloxane having hydrogen atoms (Si-H groups) bonded to silicon atoms. The Si-H groups in its molecule act as a hardener, which crosslinks with the alkenyl groups bonded to silicon atoms of the aforementioned components (A) and (B) through a silane hydroaddition reaction to harden the composition.

[0032] As component (C), it is represented by the following general formula (2). In general formula (2), R2 is an alkyl group having 1 to 10 carbon atoms, R3 is an alkyl group having 1 to 10 carbon atoms or a hydrogen atom, e is an integer of 8 or more, f is an integer of 0 to 100, e / (e+f) is 40 mol% or more, and the number of silicon atoms bonded to hydroxyl groups in one molecule is 10 or more.

[0033] Here, examples of alkyl groups having 1 to 10 carbon atoms represented by R2 include: methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tributyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, decyl, etc.; and, where some or all of the hydrogen atoms of such groups are replaced by halogen atoms such as fluorine, bromine, chlorine, or cyano, such as chloromethyl, chloropropyl, bromoethyl, trifluoropropyl, cyanoethyl, etc.; however, it is preferable that 90% or more of all R2 is methyl, and particularly preferably that all R2 groups are methyl. Furthermore, R3, in addition to those represented by R2, may include hydrogen atoms.

[0034] Furthermore, in general formula (2), e is an integer of 8 or more, preferably 10 to 200, and more preferably 12 to 100. When e is less than 8, there is a concern that the hardness will be lower than the target (e.g., 65 or more) even after secondary sulfurization. f is an integer of 0 to 100, preferably 5 to 80. Also, the molar ratio (ratio) e / (e+f) of the e unit relative to the sum of the e unit and the f unit is 40 molar% (0.4) or more, preferably 45 molar% (0.45) or more. There is no particular upper limit, for example, it can be set to 90 molar% (0.9) or less. When e / (e+f) is less than 40 molar%, the stretching during cutting after primary sulfurization will be lower, and the removal from the mold will be worse. Also, the number of silicon atoms bonded with hydrogen groups (Si-H groups) in one molecule is 10 or more, preferably 12 or more.

[0035] Specific examples of linear organohydrogen polysiloxanes as component (C) include: trimethylsiloxy-terminated methylhydrogen polysiloxanes, trimethylsiloxy-terminated dimethylsiloxane-methylhydrogen silicate copolymers, and dimethylsiloxy-terminated dimethylsiloxane-methylhydrogen silicate copolymers. One of these components may be used alone, or two or more may be used in combination.

[0036] (D) Addition reaction catalyst As an addition reaction catalyst of component (D), any catalyst used for the hydrosilicon addition reaction is acceptable and there are no particular limitations. However, examples include: platinum black, platinum tetrachloride, chloroplatinic acid, reactants of chloroplatinic acid and monovalent alcohols, complexes of chloroplatinic acid and alkenes, platinum group metal catalysts such as diacetyl acetate, palladium catalysts, and rhodium catalysts.

[0037] Other components In the addition-curing silicone adhesive composition of the present invention, the following components can be arbitrarily formulated as other components as needed: hydrogenation reaction control agents such as nitrogen-containing compounds and acetylene compounds, phosphorus compounds, nitrile compounds, carboxylic acid esters, tin compounds, mercury compounds, and sulfur compounds; internal release agents such as dimethyl silicone oil; adhesive imparting agents (especially organosilicone compounds such as alkoxysilanes containing functional groups in the molecule and not containing Si-H groups in the molecule, wherein the functional group is selected from at least one of alkenyl, epoxy, amino, (meth)acryloxy, and mercapto groups).

[0038] The amount of components (A) to (D) added to the curing silicone sealant composition is the amount of component (A) and component (B) mentioned above. The mass ratio of component (A) to component (B) is (A) / (B) = 40 / 60 to 60 / 40, preferably 45 / 55 to 55 / 45. If the proportion of component (B) is more than 60%, the hardness of the cured product after one vulcanization will become too high. If it is less than 40%, the tensile strength of the cured product after one vulcanization will be low when cutting, or the hardness will still be low after a second vulcanization.

[0039] Furthermore, regarding the formulation of component (C) in the above-mentioned addition-curing silicone rubber composition, the ratio of the total Si-H moles to the total alkenyl moles (Si-H moles / total alkenyl moles) is preferably 1.0 to 1.5, and particularly preferably 1.0 to 1.4. If it is lower than 1.0, the cured material will have strong adhesion and will still become a rubber with low hardness even after secondary vulcanization. On the other hand, if it is higher than 1.5, the hardness of the cured material after primary vulcanization will become too high, and the ability to be removed from the mold will deteriorate.

[0040] Furthermore, the amount of component (C) is preferably 7.4 parts by mass or less relative to the total of 100 parts by mass of components (A) and (B). With such an amount, the hardness and tensile strength of the hardened material after one vulcanization will be more ideal, and it will be easier to remove it from the mold.

[0041] The amount of the addition reaction catalyst, i.e., component (D), can be set as the catalyst amount, which is 0.1 to 10 ppm relative to the total mass of the components, in platinum group metals (mass conversion), preferably about 0.5 to 10 ppm. If the amount of component (D) is less than 0.1 ppm, curing will become difficult, and if it is more than 10 ppm, there is a concern that the cured product will be colored.

[0042] 〈Preparation of Addition-curing silicone adhesive composition〉 By adding and uniformly mixing the above-mentioned components (A) to (D) and any other components as needed, an addition-curing silicone adhesive composition can be prepared. However, in this mixing, any mixer used in general silicone adhesive preparation can be used, such as: a kneading machine, a gate mixer, a Shinagawa mixer, a pressure mixer, a three-roll mixer, a two-roll mixer, etc.

[0043] In the vulcanization test using a torsional vibration type conical mold vulcanization tester (B-2 method) as described in Japanese Industrial Standard JIS K 6300-2:2001, when the 10% curing time measured at 150°C for 5 minutes is set as T10 and the 90% curing time is set as T90, T90-T10 must be at least 160 seconds, preferably 160-260 seconds, and even more preferably 170-240 seconds. If it is shorter than 160 seconds, the hardness of the cured material after one vulcanization will be higher, and the tensile strength during cutting will be lower.

[0044] Thus, the addition-curing silicone adhesive composition of the present invention is characterized by a very long curing time from 10% curing to 90% curing (i.e., the curing process proceeds slowly during this period). Furthermore, T90 is less than 300 seconds (5 minutes).

[0045] <Molding of Addition-Curing Silicone Gel Composition> There are no particular limitations on the molding and curing methods of the above-mentioned addition-curing silicone gel composition. General methods can be used. As a molding method, compression molding and injection molding are suitable. In addition, during molding, in order to reduce the surface roughness of the cured material and improve its transparency, a liner with high flatness can also be used for molding. As for the curing conditions, a molded article with a specific hardness can be obtained by means of the following: using a mold at 100-180°C for 5 seconds to 30 minutes, preferably at 110-180°C for 10 seconds to 20 minutes, and most preferably at 120-160°C for about 30 seconds to 10 minutes, a first vulcanization is performed. After the cured article is removed from the mold, a second vulcanization is performed in an oven or the like at 80-200°C, especially at 100-200°C for 10 minutes to 24 hours, especially at 30 minutes to 10 hours.

[0046] <Silicone Molded Body> The addition-curing silicone composition of the present invention can impart silicone with high hardness and high transparency. The silicone molded body (elastomer) obtained by pressure curing at 120°C for 10 minutes (single curing) has a hardness (type A hardness tester) of 55 or less according to Japanese Industrial Standard JIS K 6253-3:2012, and a tensile stretch of 300% or more during cutting according to Japanese Industrial Standard JIS K 6251:2017. Furthermore, the silicone molded body (elastomer) obtained by post-curing at 150°C for 1 hour after pressure curing (secondary curing) has a hardness (type A hardness tester) of 65 or more. The above-mentioned post-cured 2mm thick molded body meets the requirements of Japanese Industrial Standard JIS K 6253-3:2012. The total light transmittance of D65 light, as described in 7361-1:1997, is 90% or higher, preferably 92% or higher. Furthermore, the haze value of the 2mm thick molded body after vulcanization is 2% or lower in the haze test using D65 light as described in Japanese Industrial Standard JIS K 7136:2000. If the hardness (type A hardness tester) of the cured material after a single vulcanization is 55 or lower and the elongation at cutting time is 300% or higher, removal from the mold becomes easier.

[0047] Thus, the addition-curing silicone sealant composition of the present invention exhibits excellent mold removal properties and, after secondary vulcanization, can impart a silicone sealant with high hardness and high transparency, making it suitable for optical applications such as LEDs. [Example]

[0048] Hereinafter, the present invention will be specifically described by way of examples and comparative examples, but the present invention is not limited to the following examples. Furthermore, in the following examples, parts refer to parts by mass. Also, the average degree of polymerization refers to the number average degree of polymerization.

[0049] [Example 1] The following components were added and stirred continuously for 15 minutes to obtain a silicone adhesive mixture. The components are: 50 parts of dimethyl polysiloxane (A-1, alkenyl content: 0.000038 mol / g), which is end-capped with dimethyl vinyl silicate and has an average degree of polymerization of 720; 50 parts of silicone resin (B-1, alkenyl content: 0.00089 mol / g, molar ratio of constituent units M:D:T:Q = 46:0:0:54, M / Q =0.85), which has an average of 3.6 vinyl groups per molecule and is a copolymer of vinyl dimethylsiloxy-trimethylsiloxy and Q units with a number average molecular weight of 4000; 6.2 parts of hydrogen polysiloxane (C-1, hydrogen methylsiloxane unit / (hydromethylsiloxane unit + dimethylsiloxane unit) = 51 mol%) as a crosslinking agent; and 0.025 parts of ethynylcyclohexanol as a reaction control agent. Furthermore, in this mixture, the mass ratio of component (A) to component (B) is (A) / (B) = 50 / 50, and the molar ratio of total Si-H groups to total alkenyl groups (Si-H groups / total alkenyl groups) is 1.1.

[0050] To this silicone sealant mixture, 0.05 parts of platinum catalyst (Pt concentration 1% by mass) were mixed to prepare a silicone sealant composition. Table 2 shows the following results for this composition: the curing properties (10% curing time T10 and 90% curing time T90) measured at 150°C for 5 minutes using a rheometer MDR2000 (manufactured by Alpha Technologies Ltd.) according to Japanese Industrial Standard JIS K 6300-2:2001; and the hardness measured by a type A hardness tester according to Japanese Industrial Standard JIS K 6253-3:2012 and the tensile strength measured during cutting according to Japanese Industrial Standard JIS K 6251:2017 for a 2 mm thick cured material obtained after pressure vulcanization (single vulcanization) at 120°C for 10 minutes. Furthermore, Table 3 shows the following results: for a 2 mm thick hardened material that has undergone post-curing (secondary curing) at 150°C / 1 hour in a baking oven after pressure curing, the hardness was measured using a type A hardness tester according to Japanese Industrial Standard JIS K 6253-3:2012, and the tensile strength during cutting was measured according to Japanese Industrial Standard JIS K 6251:2017; further, the total light transmittance of D65 light as described in Japanese Industrial Standard JIS K 7361-1:1997 and the haze test using D65 light as described in Japanese Industrial Standard JIS K 7136:2000 were measured.

[0051] [Example 2] The following components were added and stirred continuously for 15 minutes to obtain a silicone adhesive mixture, the components being: 50 parts of dimethyl polysiloxane (A-2, alkenyl content: 0.000054 mol / g), which is end-capped with dimethyl vinyl siloxy and has an average degree of polymerization of 500; 50 parts of the silicone resin (B-1) described in Example 1; 4.6 parts of hydrogen polysiloxane (C-2, hydrogen methyl siloxane unit / (hydrogen methyl siloxane unit + dimethyl siloxane unit) = 73 mol%) represented by the following formula (5) as a crosslinking agent; and 0.025 parts of ethynylcyclohexanol as a reaction control agent. Furthermore, in this mixture, the mass ratio of component (A) to component (B) is (A) / (B) = 50 / 50, and the molar ratio of total Si-H groups to total alkenyl groups (Si-H groups / total alkenyl groups) is 1.1.

[0052] To this silicone sealant mixture, 0.05 parts of platinum catalyst (Pt concentration 1% by mass) were mixed to prepare a silicone sealant composition. Table 2 shows the following results for this composition: the curing properties (10% curing time T10 and 90% curing time T90) measured at 150°C for 5 minutes using a rheometer MDR2000 (manufactured by Alpha Technologies Ltd.) according to Japanese Industrial Standard JIS K 6300-2:2001; and the hardness measured by a type A hardness tester according to Japanese Industrial Standard JIS K 6253-3:2012 and the tensile strength measured during cutting according to Japanese Industrial Standard JIS K 6251:2017 for a 2 mm thick cured material obtained after pressure vulcanization (single vulcanization) at 120°C for 10 minutes. Furthermore, Table 3 shows the following results: for a 2 mm thick hardened material that has undergone post-curing (secondary curing) at 150°C / 1 hour in a baking oven after pressure curing, the hardness was measured using a type A hardness tester according to Japanese Industrial Standard JIS K 6253-3:2012, and the tensile strength during cutting was measured according to Japanese Industrial Standard JIS K 6251:2017; further, the total light transmittance of D65 light as described in Japanese Industrial Standard JIS K 7361-1:1997 and the haze test using D65 light as described in Japanese Industrial Standard JIS K 7136:2000 were measured.

[0053] [Example 3] A silicone adhesive mixture was obtained by adding the following components and stirring continuously for 15 minutes. The components are: 55 parts of dimethyl polysiloxane (A-1) as described in Example 1; 45 parts of silicone resin (B-1) as described in Example 1; 5.3 parts of hydrogenated polysiloxane (C-2) as a crosslinking agent; and 0.025 parts of ethynylcyclohexanol as a reaction control agent. Furthermore, in this mixture, the mass ratio of component (A) to component (B) is (A) / (B) = 55 / 45, and the molar ratio of total Si-H groups to total alkenyl groups (Si-H groups / total alkenyl groups) is 1.4.

[0054] To this silicone sealant mixture, 0.05 parts of platinum catalyst (Pt concentration 1% by mass) were mixed to prepare a silicone sealant composition. Table 2 shows the following results for this composition: the curing properties (10% curing time T10 and 90% curing time T90) measured at 150°C for 5 minutes using a rheometer MDR2000 (manufactured by Alpha Technologies Ltd.) according to Japanese Industrial Standard JIS K 6300-2:2001; and the hardness measured by a type A hardness tester according to Japanese Industrial Standard JIS K 6253-3:2012 and the tensile strength measured during cutting according to Japanese Industrial Standard JIS K 6251:2017 for a 2 mm thick cured material obtained after pressure vulcanization (single vulcanization) at 120°C for 10 minutes. Furthermore, Table 3 shows the following results: for a 2 mm thick hardened material that has undergone post-curing (secondary curing) at 150°C / 1 hour in a baking oven after pressure curing, the hardness was measured using a type A hardness tester according to Japanese Industrial Standard JIS K 6253-3:2012, and the tensile strength during cutting was measured according to Japanese Industrial Standard JIS K 6251:2017; further, the total light transmittance of D65 light as described in Japanese Industrial Standard JIS K 7361-1:1997 and the haze test using D65 light as described in Japanese Industrial Standard JIS K 7136:2000 were measured.

[0055] [Example 4] The following components were added and stirred continuously for 15 minutes to obtain a silicone gel mixture, the components being: 47.5 parts of dimethyl polysiloxane (A-1) as described in Example 1; 5 parts of dimethyl polysiloxane (A-3, alkenyl content: 0.000020 mol / g), which is end-capped with dimethyl vinyl siloxy groups, has an average of 10 vinyl groups on the side chains and an average degree of polymerization of 8000; 47.5 parts of silicone resin (B-1) as described in Example 1; 7.3 parts of hydrogen polysiloxane (C-3, hydrogen methyl siloxane unit / (hydrogen methyl siloxane unit + dimethyl siloxane unit) = 50 mol%) as a crosslinking agent; and 0.025 parts of ethynylcyclohexanol as a reaction control agent. Furthermore, in this mixture, the mass ratio of component (A) to component (B) is (A) / (B) = 52.5 / 47.5, and the molar ratio of total Si-H groups to total alkenyl groups (Si-H groups / total alkenyl groups) is 1.2.

[0056] To this silicone sealant mixture, 0.05 parts of platinum catalyst (Pt concentration 1% by mass) were mixed to prepare a silicone sealant composition. Table 2 shows the following results for this composition: the curing properties (10% curing time T10 and 90% curing time T90) measured at 150°C for 5 minutes using a rheometer MDR2000 (manufactured by Alpha Technologies Ltd.) according to Japanese Industrial Standard JIS K 6300-2:2001; and the hardness measured by a type A hardness tester according to Japanese Industrial Standard JIS K 6253-3:2012 and the tensile strength measured during cutting according to Japanese Industrial Standard JIS K 6251:2017 for a 2 mm thick cured material obtained after pressure vulcanization (single vulcanization) at 120°C for 10 minutes. Furthermore, Table 3 shows the following results: for a 2 mm thick hardened material that has undergone post-curing (secondary curing) at 150°C / 1 hour in a baking oven after pressure curing, the hardness was measured using a type A hardness tester according to Japanese Industrial Standard JIS K 6253-3:2012, and the tensile strength during cutting was measured according to Japanese Industrial Standard JIS K 6251:2017; further, the total light transmittance of D65 light as described in Japanese Industrial Standard JIS K 7361-1:1997 and the haze test using D65 light as described in Japanese Industrial Standard JIS K 7136:2000 were measured.

[0057] [Comparative Example 1] A silicone resin mixture was obtained by adding the following components and stirring continuously for 15 minutes. The components were: 50 parts of dimethyl polysiloxane (A-4, alkenyl content: 0.000060 mol / g), which was end-capped with dimethyl vinylsiloxy groups and had an average degree of polymerization of 450; 50 parts of the silicone resin (B-1) described in Example 1; 4.7 parts of hydrogen polysiloxane (C-2) described in Example 2 as a crosslinking agent; and 0.025 parts of ethynylcyclohexanol as a reaction control agent. Furthermore, in this mixture, the mass ratio of component (A) to component (B) was (A) / (B) = 50 / 50, and the molar ratio of total Si-H groups to total alkenyl groups (Si-H groups / total alkenyl groups) was 1.1.

[0058] To this silicone sealant mixture, 0.05 parts of platinum catalyst (Pt concentration 1% by mass) were mixed to prepare a silicone sealant composition. Table 2 shows the following results for this composition: the curing properties (10% curing time T10 and 90% curing time T90) measured at 150°C for 5 minutes using a rheometer MDR2000 (manufactured by Alpha Technologies Ltd.) according to Japanese Industrial Standard JIS K 6300-2:2001; and the hardness measured by a type A hardness tester according to Japanese Industrial Standard JIS K 6253-3:2012 and the tensile strength measured during cutting according to Japanese Industrial Standard JIS K 6251:2017 for a 2 mm thick cured material obtained after pressure vulcanization (single vulcanization) at 120°C for 10 minutes. Furthermore, Table 3 shows the following results: for a 2 mm thick hardened material that has undergone post-curing (secondary curing) at 150°C / 1 hour in a baking oven after pressure curing, the hardness was measured using a type A hardness tester according to Japanese Industrial Standard JIS K 6253-3:2012, and the tensile strength during cutting was measured according to Japanese Industrial Standard JIS K 6251:2017; further, the total light transmittance of D65 light as described in Japanese Industrial Standard JIS K 7361-1:1997 and the haze test using D65 light as described in Japanese Industrial Standard JIS K 7136:2000 were measured.

[0059] [Comparative Example 2] A silicone adhesive mixture was obtained by adding the following components and stirring continuously for 15 minutes. The components were: 61 parts of dimethyl polysiloxane (A-1) as described in Example 1; 39 parts of silicone resin (B-1) as described in Example 1; 4.7 parts of hydrogen polysiloxane (C-2) as a crosslinking agent; and 0.025 parts of ethynylcyclohexanol as a reaction control agent. Furthermore, in this mixture, the mass ratio of component (A) to component (B) was (A) / (B) = 61 / 39, and the molar ratio of total Si-H groups to total alkenyl groups (Si-H groups / total alkenyl groups) was 1.4.

[0060] To this silicone sealant mixture, 0.05 parts of platinum catalyst (Pt concentration 1% by mass) were mixed to prepare a silicone sealant composition. Table 2 shows the following results for this composition: the curing properties (10% curing time T10 and 90% curing time T90) measured at 150°C for 5 minutes using a rheometer MDR2000 (manufactured by Alpha Technologies Ltd.) according to Japanese Industrial Standard JIS K 6300-2:2001; and the hardness measured by a type A hardness tester according to Japanese Industrial Standard JIS K 6253-3:2012 and the tensile strength measured during cutting according to Japanese Industrial Standard JIS K 6251:2017 for a 2 mm thick cured material obtained after pressure vulcanization (single vulcanization) at 120°C for 10 minutes. Furthermore, Table 3 shows the following results: for a 2 mm thick hardened material that has undergone post-curing (secondary curing) at 150°C / 1 hour in a baking oven after pressure curing, the hardness was measured using a type A hardness tester according to Japanese Industrial Standard JIS K 6253-3:2012, and the tensile strength during cutting was measured according to Japanese Industrial Standard JIS K 6251:2017; further, the total light transmittance of D65 light as described in Japanese Industrial Standard JIS K 7361-1:1997 and the haze test using D65 light as described in Japanese Industrial Standard JIS K 7136:2000 were measured.

[0061] [Comparative Example 3] A silicone adhesive mixture was obtained by adding the following components and stirring continuously for 15 minutes. The components were: 55 parts of dimethyl polysiloxane (A-1) as described in Example 1; 45 parts of silicone resin (B-1) as described in Example 1; 9.8 parts of hydrogen polysiloxane (C-3) as a crosslinking agent; and 0.025 parts of ethynylcyclohexanol as a reaction control agent. Furthermore, in this mixture, the mass ratio of component (A) to component (B) was (A) / (B) = 55 / 45, and the molar ratio of total Si-H groups to total alkenyl groups (Si-H groups / total alkenyl groups) was 1.6.

[0062] To this silicone sealant mixture, 0.05 parts of platinum catalyst (Pt concentration 1% by mass) were mixed to prepare a silicone sealant composition. Table 2 shows the following results for this composition: the curing properties (10% curing time T10 and 90% curing time T90) measured at 150°C for 5 minutes using a rheometer MDR2000 (manufactured by Alpha Technologies Ltd.) according to Japanese Industrial Standard JIS K 6300-2:2001; and the hardness measured by a type A hardness tester according to Japanese Industrial Standard JIS K 6253-3:2012 and the tensile strength measured during cutting according to Japanese Industrial Standard JIS K 6251:2017 for a 2 mm thick cured material obtained after pressure vulcanization (single vulcanization) at 120°C for 10 minutes. Furthermore, Table 3 shows the following results: for a 2 mm thick hardened material that has undergone post-curing (secondary curing) at 150°C / 1 hour in a baking oven after pressure curing, the hardness was measured using a type A hardness tester according to Japanese Industrial Standard JIS K 6253-3:2012, and the tensile strength during cutting was measured according to Japanese Industrial Standard JIS K 6251:2017; further, the total light transmittance of D65 light as described in Japanese Industrial Standard JIS K 7361-1:1997 and the haze test using D65 light as described in Japanese Industrial Standard JIS K 7136:2000 were measured.

[0063] [Comparative Example 4] A silicone gel mixture was obtained by adding the following components and stirring continuously for 15 minutes. The components were: 50 parts of dimethyl polysiloxane (A-1) as described in Example 1; 50 parts of silicone resin (B-1) as described in Example 1; 10.8 parts of hydrogen polysiloxane (C-4, hydrogen methyl silicate unit / (hydrogen methyl silicate unit + dimethyl silicate unit) = 36 mol%) as a crosslinking agent; and 0.025 parts of ethynylcyclohexanol as a reaction control agent. Furthermore, in this mixture, the mass ratio of component (A) to component (B) was (A) / (B) = 50 / 50, and the molar ratio of total Si-H groups to total alkenyl groups (Si-H groups / total alkenyl groups) was 1.2.

[0064] To this silicone sealant mixture, 0.05 parts of platinum catalyst (Pt concentration 1% by mass) were mixed to prepare a silicone sealant composition. Table 2 shows the following results for this composition: the curing properties (10% curing time T10 and 90% curing time T90) measured at 150°C for 5 minutes using a rheometer MDR2000 (manufactured by Alpha Technologies Ltd.) according to Japanese Industrial Standard JIS K 6300-2:2001; and the hardness measured by a type A hardness tester according to Japanese Industrial Standard JIS K 6253-3:2012 and the tensile strength measured during cutting according to Japanese Industrial Standard JIS K 6251:2017 for a 2 mm thick cured material obtained after pressure vulcanization (single vulcanization) at 120°C for 10 minutes. Furthermore, Table 3 shows the following results: for a 2 mm thick hardened material that has undergone post-curing (secondary curing) at 150°C / 1 hour in a baking oven after pressure curing, the hardness was measured using a type A hardness tester according to Japanese Industrial Standard JIS K 6253-3:2012, and the tensile strength during cutting was measured according to Japanese Industrial Standard JIS K 6251:2017; further, the total light transmittance of D65 light as described in Japanese Industrial Standard JIS K 7361-1:1997 and the haze test using D65 light as described in Japanese Industrial Standard JIS K 7136:2000 were measured.

[0065] The dosage of each component used in Examples 1-4 and Comparative Examples 1-4 is shown in Table 1.

[0066] [Table 1] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 A-1 (copy) 50 55 47.5 61 55 50 A-2 (copies) 50 A-3 (copies) 5 A-4 (copies) 50 B-1 (copy) 50 50 45 47.5 50 39 45 50 C-1 (copy) 6.2 C-2 (portions) 4.6 5.3 4.7 4.7 C-3 (portions) 7.3 9.8 C-4 (portions) 10.8 Platinum catalyst (Pt concentration per 1% by mass) (parts) 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 Ethynylcyclohexanol (parts) 0.025 0.025 0.025 0.025 0.025 0.025 0.025 0.025 (A) / (B) 50 / 50 50 / 50 50 / 45 52.5 / 47.5 50 / 50 61 / 39 55 / 45 50 / 50 (Si-H group / total alkenyl group) 1.1 1.1 1.4 1.2 1.1 1.4 1.6 1.2

[0067] [Table 2] Example Comparative example 1 2 3 4 1 2 3 4 Hardening T10 (seconds) 18 17 17 17 17 16 15 17 Hardening T90 (seconds) 198 203 200 205 203 169 133 196 T90-T10 (seconds) 180 186 183 188 186 153 118 179 Hardness: Type A hardness tester (After one sulfur addition) 53 50 50 53 48 37 60 59 Stretch during cutting (%) (After one sulfur addition) 390 310 430 340 240 390 100 130

[0068] [Table 3] Example Comparative example 1 2 3 4 1 2 3 4 Hardness: Type A hardness tester (After secondary sulfur addition) 69 68 68 68 68 54 71 72 Stretch during cutting (%) (After secondary sulfur addition) 340 270 400 100 200 390 80 100 Total light transmittance (%) 95 95 95 95 95 95 95 95 Haze (%) 1 1 1 1 1 1 1 1

[0069] As shown in Tables 2 and 3, the addition-curing silicone rubber compositions of Examples 1 to 4 can obtain an addition-curing silicone rubber composition with a hardness (type A hardness tester) of less than 55 after one vulcanization, an elongation of more than 300% during cutting, and a hardness of more than 65 after two vulcanizations and high transparency.

[0070] On the other hand, in Comparative Example 1, which uses linear organic polysiloxanes with an average degree of polymerization of less than 480, the tensile strength of the rubber after one vulcanization is lower. In Comparative Example 2, where the mass ratio of component (A) to component (B) is outside the range of (A) / (B) = 40 / 60 to 60 / 40, the hardness is still lower even after two vulcanizations.

[0071] Furthermore, in Comparative Example 3, where the ratio of the total Si-H moles to the total alkenyl moles (Si-H moles / total alkenyl moles) in the composition is outside the range of 1.0 to 1.5, the hardness after one sulfurization is higher and the tensile strength during cutting is lower. In Comparative Example 4, where the ratio of hydrogen methyl silicate unit / (hydromethyl silicate unit + dimethyl silicate unit) is not more than 40 moles, the hardness of the cured product after one sulfurization is higher and the tensile strength during cutting is lower.

[0072] As described above, any addition-curing silicone resin composition of the present invention will become an addition-curing silicone resin composition that can impart excellent removability from the mold and high transparency to the cured material.

[0073] Furthermore, the present invention is not limited to the embodiments described above. The embodiments described above are examples, but those having a structure substantially the same as the technical concept described in the claims of the present invention and capable of performing the same effects are all included within the technical scope of the present invention.

Claims

1. An addition-curable silicone sealant composition, characterized by comprising the following components: (A) a linear organopolysiloxane having an average degree of polymerization of 480 or more and containing at least two alkenyl groups bonded to silicon atoms in one molecule; (B) an alkenyl-containing silicone resin represented by the following general formula (1), (R13SiO1 / 2)a(R12SiO2 / 2)b(R1SiO3 / 2)c(SiO4 / 2)d (1) In general formula (1), R1 is an independent monovalent hydrocarbon group selected from alkyl groups having 1 to 10 carbon atoms and alkenyl groups having 2 to 10 carbon atoms, having an average of 2.5 or more alkenyl groups in one molecule, and 0 < a ≦ 0.7, 0 ≦ b ≦ 0.2, 0 ≦ c ≦ 0.2, 0 < d ≦ 0.7, wherein, (C) A linear organohydrogen polysiloxane represented by the following general formula (2), wherein R2 is an alkyl group having 1 to 10 carbon atoms, R3 is an alkyl group having 1 to 10 carbon atoms or a hydrogen atom, e is an integer of 8 or more, f is an integer of 5 to 9 or 11 to 100, e / (e+f) is 40 mol% or more and the number of hydrogen groups bonded to silicon atoms in one molecule is 10 or more; and (D) an addition reaction catalyst having a total mass of 0.1 to 10 ppm relative to the composition, calculated by mass conversion of platinum group metals. In this addition-curing silicone rubber composition, the mass ratio of the aforementioned component (A) to the aforementioned component (B) is (A) / (B) = 40 / 60 to 60 / 40, the ratio of the total Si-H moles to the total alkenyl moles (Si-H moles / total alkenyl moles) in the composition is 1.0 to 1.5, and in the vulcanization test using a torsional vibration type conical mold vulcanization tester (B-2 method) as described in Japanese Industrial Standard JIS K 6300-2:2001, when the 10% curing time measured at 150°C for 5 minutes is set as T10, and the 90% curing time is set as T90, T90-T10 is 160 seconds or more, and the alkenyl content of the aforementioned component (B) is 0.0006 to 0.001 mol / g.

2. The addition-curing silicone sealant composition as described in claim 1, wherein, The alkenyl content of the aforementioned component (A) is less than 0.00006 mol / g.