Pressure-sensitive adhesive layer-forming organopolysiloxane composition and use thereof

Abstract

[Problem] To provide: an organopolysiloxane composition having curing reaction properties, the composition forming a pressure-sensitive adhesive layer that has a high shear storage elastic modulus, high stress during 500% warping, and strong adhesiveness with respect to a substrate; and a use for the composition [Solution] An organopolysiloxane composition having pressure-sensitive adhesive layer formation properties, the composition containing: (A) a chain-form organopolysiloxane having an alkenyl group; (B) a mixture that is an organopolysiloxane resin in which the hydroxyl group content, etc., is 9 mol% or less, the mixture including (b1) a component that has a molecular weight (Mw) of 4500 or higher, and (b2) a component that has a molecular weight (Mw) less than 4500; (C) an organo-hydrogen polysiloxane; and (D) a hydrosilylation reaction catalyst. The mass ratio of the resin component relative to the chain-form siloxane component is within the range of 1.4-3.0, the shear storage elastic modulus G' at 25°C of a pressure-sensitive adhesive layer obtained by curing the composition is 3.5 MPa or higher, and the stress during 500% warping is 0.25 MPa or higher.

Description

[Technical field]

[0001] The present invention relates to a curable reactive organopolysiloxane composition for forming a pressure-sensitive adhesive layer and its use. [Background technology]

[0002] Compared with acrylic or rubber-based pressure-sensitive adhesive compositions, polysiloxane-based pressure-sensitive adhesive compositions are excellent in electrical insulation, heat resistance, cold resistance, adhesion to various adherends, and transparency as required, and therefore, addition reaction curing type pressure-sensitive adhesive compositions in particular are widely used. In recent years, applications to advanced electronic materials such as smart devices, display element fields, speakers, etc. have been considered, and polysiloxane-based pressure-sensitive adhesives with excellent heat and cold resistance are expected to be effective in protecting electrode layers and display layers and improving adhesion between layers.

[0003] In particular, in recent material development, there is a demand for polysiloxane-based pressure-sensitive adhesive compositions that have a high degree of freedom in designing the storage modulus (e.g., shear storage modulus G') over a wide temperature range, including low temperatures such as -20°C, that have excellent curing properties, and that have adhesive strength sufficient for practical use. However, the pressure-sensitive adhesive compositions described in publicly known literature do not fully satisfy these properties, and there is still room for improvement.

[0004] For example, Patent Document 1 discloses an adhesive rubber sheet, but the ratio of the resin component and the siloxane polymer component is such that the resin component content is low, and there is no mention or suggestion of the use of a combination of a resin component with specific properties such as molecular weight, hydroxyl group content, etc. Furthermore, the adhesive rubber sheet uses finely powdered silica, etc., and does not satisfy the storage modulus (G') targeted by the present invention.

[0005] Similarly, Patent Document 2 discloses a silicone pressure-sensitive adhesive that uses an organopolysiloxane resin with a number average molecular weight of 950 to 1600, but does not mention or suggest the use of a combination of resin components that differ in molecular weight and have specific properties such as the content of hydroxyl groups. Furthermore, although the silicone pressure-sensitive adhesive has a certain level of adhesive strength, it does not satisfy the storage modulus (G') that is the objective of the present invention.

[0006] On the other hand, Patent Document 3 proposes a laminate having a transparent resin adhesive layer characterized by a ratio of the amount of substance of the resin component to the polymer component in the range of 0.5 to 1.0 and a small difference in storage modulus G' between low temperature and room temperature. However, only condensation-reactive transparent resin adhesive layers are specifically disclosed, and there is a problem that the curing reaction is too slow for industrial use. Furthermore, the transparent resin adhesive layer does not satisfy the storage modulus (G') and adhesive strength sufficient for practical use that are the objectives of the present invention.

[0007] Here, the present applicants have proposed a curable silicone composition capable of forming a cured layer having a sufficient elastic modulus and loss factor (tan δ) for flexible laminate applications in Patent Document 4. However, the compositions specifically disclosed in the examples and the like disclose a combination of resin components with different weight average molecular weights in some parts, but do not fully solve the problems of the present invention. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2006-225420 A [Patent Document 2] Japanese Patent Application Publication No. 05-214316 [Patent Document 3] International Patent Publication No. 2017-082654 [Patent Document 4] International Patent Publication No. 2017-188308 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made to solve the above problems, and aims to provide a curing-reactive organopolysiloxane composition that has sufficient curability for practical use, has a high shear storage modulus and stress at 500% strain, and forms a pressure-sensitive adhesive layer that has strong adhesive strength to a substrate. Another aim of the present invention is to provide the use of the curing-reactive organopolysiloxane composition or a cured product thereof as a pressure-sensitive adhesive layer, as an elastic adhesive member in a wide range of applications, and to provide an apparatus or device equipped with them. [Means for solving the problem]

[0010] The present inventors have intensively studied the above problems and have arrived at the present invention. That is, one of the objects of the present invention is achieved by a hydrosilylation reaction-curable pressure-sensitive adhesive layer-forming organopolysiloxane composition, in which the sum of the content of hydroxyl groups and hydrolyzable groups relative to the total silicon atoms in the molecule is 9 mol% or less, two or more organopolysiloxane resins having different molecular weight ranges are used in combination, the mass ratio of the organopolysiloxane resin to the linear organopolysiloxane is adjusted to the range of 0.9 to 4.0, and the pressure-sensitive adhesive layer obtained by curing the composition has a shear storage modulus G' at 25°C of 3.5 MPa or more and a stress at 500% strain at 25°C of 0.25 MPa or more. Furthermore, the above-mentioned object can be achieved by using the curing reactive organopolysiloxane composition or a cured product thereof as a pressure-sensitive adhesive layer, or as a membrane for an electronic material, a member for a display device, a speaker, or the like, or by using electronic components, displays, or speakers equipped with them. Effect of the Invention

[0011] The pressure-sensitive adhesive layer-forming organopolysiloxane composition of the present invention has excellent curing properties by hydrosilylation reaction, and can form a pressure-sensitive adhesive layer having a high shear storage modulus and stress at 500% strain, and strong adhesive strength to a substrate. Furthermore, the curing reactive organopolysiloxane composition or its cured product can be suitably used as a pressure-sensitive adhesive layer, electronic material, or display device member, and an electric / electronic component or display device equipped with them can form a pressure-sensitive adhesive layer that does not easily cause problems of poor curing and poor adhesion to a substrate such as an electronic component in a temperature range including low temperature to room temperature, since the viscoelasticity of the adhesive layer is sufficient in a wide temperature range including low temperature to room temperature by satisfying the above-mentioned required properties, and thus is easy to industrialize, and the performance of the laminate such as the display device and speaker obtained is expected to be improved. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] [Pressure-sensitive adhesive layer-forming organopolysiloxane composition] First, the pressure-sensitive adhesive layer-forming organopolysiloxane composition of the present invention will be described. The composition cures quickly by a curing reaction including a hydrosilylation reaction, and forms a pressure-sensitive adhesive layer having a high shear storage modulus and a high stress at 500% strain, and a strong adhesive strength to a substrate. Below, each of the components, the range of the organopolysiloxane resin mixture, which is a technical feature, the mass ratio of the organopolysiloxane resin to the linear organopolysiloxane, and the properties of the pressure-sensitive adhesive layer will be described.

[0013] As described above, the organopolysiloxane composition of the present invention cures by hydrosilylation reaction to form a pressure-sensitive adhesive layer having a certain adhesive strength, in which the sum of the content of hydroxyl groups and hydrolyzable groups relative to the total silicon atoms in the molecule is 9 mol% or less, a mixture of organopolysiloxane resins having different molecular weight ranges is used, and the range of the organopolysiloxane resin blended with the main component, the linear organopolysiloxane having alkenyl groups, is within a specific range. The pressure-sensitive adhesive layer obtained by curing the composition having these characteristics has a shear storage modulus G' at 25°C of 3.5 MPa or more, a stress at 500% strain at 25°C of 0.25 MPa or more, and preferably also has a certain adhesive strength.

[0014] Specifically, the organopolysiloxane composition of the present invention comprises: (A) a linear organopolysiloxane having an average of more than one alkenyl group in the molecule; (B) An organopolysiloxane resin mixture comprising the following components (b1) and (b2) in a mass ratio of 1:99 to 99:1: (b1) An organopolysiloxane resin in which the sum of the content of hydroxyl groups and hydrolyzable groups relative to the total silicon atoms in the molecule is 9 mol % or less and the weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) relative to standard polystyrene is 4,500 or more; (b2) An organopolysiloxane resin in which the sum of the content of hydroxyl groups and hydrolyzable groups relative to the total silicon atoms in the molecule is 9 mol % or less, and the weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) relative to standard polystyrene is less than 4,500. (C) an organohydrogenpolysiloxane having at least two Si-H bonds in the molecule; (D) an effective amount of a hydrosilylation reaction catalyst, and Optionally, (A') a linear organopolysiloxane that does not contain a carbon-carbon double bond-containing reactive group in the molecule. In addition, since the composition contains a hydrosilylation reaction catalyst, from the viewpoint of handling and workability, it may further contain a cure retarder (E), and may contain other additives within the scope of the present invention. Each component will be described below.

[0015] The alkenyl-containing organopolysiloxane of component (A) is a chain-like polysiloxane molecule, which is the main component (base polymer) of this composition, and contains an average of more than one alkenyl group bonded to a silicon atom per molecule, with the preferred number of alkenyl groups being 1.5 or more per molecule. The alkenyl group of the organopolysiloxane of component (A) may be an alkenyl group having 2 to 10 carbon atoms, and is particularly preferably a vinyl group or a hexenyl group. The bonding position of the alkenyl group of component (A) may be, for example, the molecular chain terminal and / or the molecular chain side chain. Note that component (A) may contain only a single component, or may be a mixture of two or more different components.

[0016] In the organopolysiloxane of component (A), examples of organic groups bonded to silicon atoms other than alkenyl groups include alkyl groups such as methyl groups; aryl groups such as phenyl groups; aralkyl groups; and halogenated alkyl groups, with methyl groups and phenyl groups being particularly preferred.

[0017] Unlike component (B), component (A) has a chain-like polysiloxane molecular structure. For example, component (A) is preferably linear or partially branched linear (branched), and may also be partially cyclic or three-dimensionally networked. It is preferably a linear or branched diorganopolysiloxane whose main chain is composed of repeated diorganosiloxane units and whose molecular chain is blocked at both ends with triorganosiloxy groups. The siloxane units that give branched organopolysiloxanes are T units or Q units, which will be described later.

[0018] The properties of component (A) at room temperature may be oil-like or rubber-like, and it is preferable that component (A) has a viscosity of 50 mPa·s or more, and particularly 100 mPa·s or more, at 25° C. In particular, when the organopolysiloxane composition according to the present invention is a solvent-based composition, it is preferable that at least a portion of component (A) is (A1) a rubber-like alkenyl-group-containing organopolysiloxane having a viscosity of 100,000 mPa·s or more at 25° C. or a plasticity measured in accordance with the method specified in JIS K6249 (a 4.2 g spherical sample is subjected to a load of 1 kgf for 3 minutes at 25° C., the thickness is read to the nearest 1 / 100 mm, and this value is multiplied by 100) in the range of 50 to 200, and more preferably in the range of 80 to 180.

[0019] From the viewpoint of preventing contact failure, it is preferable that these alkenyl group-containing organopolysiloxanes have reduced or removed volatile or low molecular weight siloxane oligomers (octamethyltetrasiloxane (D4), decamethylpentasiloxane (D5), etc.) The extent of this can be designed as desired, but it may be less than 1 mass% of the entire component (A), less than 0.1 mass% for each siloxane oligomer, or may be reduced to near the detection limit as necessary.

[0020] The content of alkenyl groups in the component (A1) is not particularly limited, but from the viewpoint of the technical effect of the present invention, the content of vinyl (CH2=CH) moieties in the alkenyl groups in the component (A1) (hereinafter referred to as "vinyl content") is preferably in the range of 0.005 to 0.400 mass%, and particularly preferably in the range of 0.02 to 0.300 mass%. When the vinyl content in the alkenyl groups in the component (A1) is 0.02 mass% or more, it is easy to obtain a high storage modulus and tensile stress, but at the same time, it is difficult to obtain a high adhesive strength of 2000 gf / inch or more, measured against a 2 mm thick polymethyl methacrylate sheet by using a 180° peel test method according to JIS Z 0237 at a tensile speed of 300 mm / min, for a 50 μm thick pressure-sensitive adhesive layer obtained by curing the composition.

[0021] However, in the present invention, by setting the mass ratio of the linear organopolysiloxane to the organopolysiloxane resin within a specified range and using a specified organopolysiloxane resin mixture, it is possible to simultaneously achieve these. On the other hand, when the vinyl content in the alkenyl group in the (A1) component is less than the lower limit, particularly less than 0.02 mass%, the tensile stress of the pressure-sensitive adhesive layer obtained is relatively low, but it is possible to obtain a shear storage modulus G' at 25°C of 3.5 MPa or more, a stress at 500% strain at 25°C of 0.25 MPa or more, and an extremely high adhesive strength of more than 2500 gf / inch under the above conditions. That is, in the present invention, by setting the vinyl content of the (A1) component within the above range, in addition to viscoelastic properties and stress sufficient for practical use, strong adhesive strength is also realized.

[0022] As the component (A) of the present invention, it is possible to use a component (A) having a lower viscosity than the aforementioned component (A1), specifically, (A2) an alkenyl group-containing organopolysiloxane having a viscosity of less than 100,000 mPa s at 25° C. Here, examples of component (A2) other than the viscosity are the same as those of component (A1).

[0023] From the viewpoint of the technical effects of the present invention, it is preferable that 50% by mass or more of the component (A) is the high polymerization degree alkenyl-containing organopolysiloxane (A1), and it is particularly preferable that 75 to 100% by mass is the component (A1). That is, when the component (A1) (= high polymerization degree alkenyl-containing organopolysiloxane) and the component (A2) (= lower polymerization degree alkenyl-containing organopolysiloxane) are used in combination as the component (A) of the present invention, the mass ratio of the two is in the range of 50:50 to 100:0, more preferably 75:25 to 100:0 or 75:25 to 90:10.

[0024] [Other cyclic siloxanes and organosilicon compounds having alkenyl groups] In the present invention, a small amount of cyclic siloxanes having an alkenyl group, such as 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, may be used together with component (A) as an option. These cyclic siloxanes may function as reactive diluents or curing reactivity regulators, and may be used as needed.

[0025] Similarly, optionally, an organosilicon compound having an average of more than one alkenyl group in the molecule may be used together with component (A), which does not fall under the above-mentioned components (A), (B), and cyclic siloxanes having an alkenyl group. These organosilicon compounds are usually reaction mixtures of alkenyl-containing silanes and alkenyl-containing silanes-siloxanes used as independent adhesion promoters in curable siloxane compositions, and are different from polyorganosiloxane components such as polydialkylsiloxanes and organopolysiloxane resin components. These organosilicon compounds having an alkenyl group and further having an epoxy group in the molecule are excellent in handling and workability, and can be rapidly cured by a hydrosilylation curing reaction without impairing viscoelastic properties such as shear storage modulus G' at room temperature. In addition, they can impart good adhesion to various substrates, and in particular, they may be capable of forming a pressure-sensitive adhesive layer having excellent tensile adhesive strength.

[0026] The organopolysiloxane resin mixture (B) is one of the characteristic components of the present invention, and is a tackifier that imparts adhesion to a substrate, and at the same time, when used in a certain ratio with component (A), it is a component that realizes the storage modulus, stress, and practical range of adhesion that are the objectives of the present invention. More specifically, component (B) is a mixture of organopolysiloxane resins with different average molecular weights in which the content of hydroxyl groups or hydrolyzable groups is suppressed, and hydrolysis / polymerization reactions between components (B) are unlikely to occur, and by using a combination of resins with different average molecular weights, it is possible to realize the desired storage modulus, stress, and practical range of adhesion in the pressure-sensitive adhesive layer, which is the cured product.

[0027] Specifically, the component (B) is an organopolysiloxane resin mixture containing the following components (b1) and (b2) in a mass ratio of 1:99 to 99:1. (b1) An organopolysiloxane resin in which the sum of the content of hydroxyl groups and hydrolyzable groups relative to the total silicon atoms in the molecule is 9 mol % or less and the weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) relative to standard polystyrene is 4,500 or more; (b2) An organopolysiloxane resin in which the sum of the content of hydroxyl groups and hydrolyzable groups relative to the total silicon atoms in the molecule is 9 mol % or less, and the weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) relative to standard polystyrene is less than 4,500.

[0028] The (B) component in the present invention, i.e., the (b1) component and the (b2) component, have a common property that the sum of the contents of hydroxyl groups and hydrolyzable groups in the molecule is in the range of 9 mol% or less with respect to the total silicon atoms in the organopolysiloxane resin molecule, and is preferably 7 mol% or less with respect to the total silicon atoms in the molecule. The contents of hydroxyl groups and hydrolyzable groups in the (B) component can also be expressed by converting all of these functional groups into hydroxyl groups. In this case, if the mass% is calculated assuming that all of the hydrolyzable groups other than hydroxyl groups in the organopolysiloxane resin molecule are hydroxyl groups (OH), the sum of the contents of the above hydroxyl groups and hydrolyzable groups can also be expressed as the sum of the contents of hydroxyl groups and the hydrolyzable groups converted into hydroxyl groups in the organopolysiloxane resin molecule is 2.0 mass% or less, and preferably 1.6 mass% or less. Hydroxyl groups or hydrolyzable groups are directly bonded to silicon in T units or Q units of the siloxane units in the resin structure described below, and are groups derived from the raw silane or generated as a result of hydrolysis of the silane. Therefore, the content of hydroxyl groups or hydrolyzable groups can be reduced by hydrolyzing the synthesized organopolysiloxane resin with a silylating agent such as trimethylsilane.

[0029] In the (b1) and (b2) components, if the amount of the hydroxyl group or hydrolyzable group exceeds the upper limit, the condensation reaction between the organopolysiloxane resin molecules proceeds, and an organopolysiloxane resin structure with a large molecular weight is likely to be formed in the cured product. Such an organopolysiloxane resin with a large molecular weight tends to impair the curability of the entire composition, and the curability of the composition at low temperatures may become insufficient, or the resulting pressure-sensitive adhesive layer may not have a storage modulus sufficient for practical use.

[0030] Both components (b1) and (b2) are organopolysiloxane resins, and are organopolysiloxanes having a three-dimensional structure. For example, RSiO 2 / 2 Units (D units) and RSiO 3 / 2 units (T units) (wherein R each independently represent a monovalent organic group) and the content of hydroxyl groups or hydrolyzable groups is within the above range, a resin consisting of only T units and the content of hydroxyl groups or hydrolyzable groups is within the above range, and RSiO 1 / 2 Units (M units) and SiO 4 / 2 In particular, RSiO 1 / 2 Units (M units) and SiO 4 / 2 It is preferable to use a resin (also called MQ resin) that is composed of units (Q units) and in which the sum of the contents of hydroxyl groups and hydrolyzable groups relative to all silicon atoms in the molecule is in the range of 0 to 7 mol % (preferably 0.0 to 1.6 mass % when all of these functional groups are converted into hydroxyl groups).

[0031] The monovalent organic group of R is preferably a monovalent hydrocarbon group having 1 to 10 carbon atoms, and examples thereof include an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, a cycloalkyl group having 6 to 10 carbon atoms, a benzyl group, a phenylethyl group, and a phenylpropyl group. In particular, it is preferable that 90 mol % or more of R are alkyl groups having 1 to 6 carbon atoms or phenyl groups, and it is particularly preferable that 95 to 100 mol % of R are methyl groups or phenyl groups.

[0032] The components (b1) and (b2) are RSiO 1 / 2 Units (M units) and SiO 4 / 2 In the case of a resin consisting of units (Q units), the molar ratio of M units to Q units is preferably 0.5 to 2.0. If this molar ratio is less than 0.5, the adhesive strength to the substrate may decrease, and if it is more than 2.0, the cohesive strength of the substance constituting the adhesive layer decreases. In addition, it is also possible to contain D units and T units in component (B) within a range that does not impair the characteristics of the present invention. Furthermore, from the viewpoint of preventing contact failure, etc., these organopolysiloxane resins may have reduced or removed low molecular weight siloxane oligomers.

[0033] The organopolysiloxane resins of components (b1) and (b2) differ from each other in their weight average molecular weight (Mw), which is the average molecular weight that takes into account the proportion of each molecule in the whole of each organopolysiloxane resin, as measured by gel permeation chromatography (GPC) using standard polystyrene as the conversion factor.

[0034] The component (b1) is an organopolysiloxane resin having a high molecular weight, and its weight average molecular weight (Mw) is 4500 or more, preferably 5000 or more, and particularly preferably 5500 or more. In practice, the component (b1) is the above-mentioned R3SiO 1 / 2 Units (M units) and SiO 4 / 2 Resins made of units (Q units) are particularly suitable.

[0035] Component (b2) is a low molecular weight organopolysiloxane resin, the weight average molecular weight (Mw) of which is less than 4500, preferably 4000 or less, and particularly preferably 3750 or less. In practice, component (b1) is the above-mentioned R3SiO 1 / 2 Units (M units) and SiO 4 / 2Resins made of units (Q units) are particularly suitable.

[0036] Component (B) is an organopolysiloxane resin mixture containing the above-mentioned components (b1) and (b2) in a mass ratio of 1:99 to 99:1, and the mixing ratio is not particularly limited, but may be in the range of 5:95 to 95:5, 10:90 to 90:10, or 15:85 to 85:15 depending on the composition and viscoelasticity design. On the other hand, the present invention is characterized by the use of two or more resin components having different molecular weights in substantial combination, and if component (B) is not a mixture of these organopolysiloxane resins having different molecular weights or the mixing ratio is outside the above upper and lower limits, the properties such as curability, adhesion, and storage modulus that are the objective of the present invention may not be realized even if the content of hydroxyl groups or hydrolyzable groups in the resin components is 2.0 mass% or less.

[0037] [Mass ratio of component (B) to components (A) and (A')] The pressure-sensitive adhesive layer-forming organopolysiloxane composition according to the present invention is characterized in that the mass ratio of the organopolysiloxane resin (B) component to the sum of the chain-like reactive siloxane component (A) and the later-described component (A') is in the range of 1.4 to 4.0. When the above-described characteristic organopolysiloxane resin mixture is selected as the component (B) and the above-described resin component is blended with the chain-like siloxane polymer component in the above-described range, the high storage modulus and viscoelastic properties such as stress that are the object of the present invention are suitably realized. In particular, from the viewpoint of increasing the adhesive strength of the obtained pressure-sensitive adhesive layer, the mass ratio of the (B) component to the (A) component and the later-described component (A') may be in the range of 1.9 to 4.0, and in order to realize the desired adhesive strength and storage modulus, the range of 1.9 to 3.5 is particularly preferred. On the other hand, if the mass ratio of the (B) component to the (A) component and the (A') component described below is outside the above range, the properties such as curability, adhesive strength, and storage modulus intended by the present invention may not be achieved even if other components are adjusted.

[0038] Component (C) is an organohydrogenpolysiloxane having two or more Si-H bonds in the molecule, and is a crosslinking agent for the organopolysiloxane composition of the present invention. The molecular structure of component (C) is not limited, and examples thereof include linear, partially branched linear, branched, cyclic, and organopolysiloxane resin, and preferably linear, partially branched linear, or organopolysiloxane resin. The bonding position of the silicon-bonded hydrogen atom is not particularly limited, and examples thereof include the molecular chain terminal, the side chain, and both. The content of silicon-bonded hydrogen atoms is preferably from 0.1 to 2.0 mass %, and more preferably from 0.5 to 1.7 mass %.

[0039] Examples of organic groups bonded to silicon atoms include alkyl groups having 1 to 8 carbon atoms, such as methyl groups; aryl groups, such as phenyl groups; aralkyl groups; and halogenated alkyl groups, and it is preferable that at least 50 mol % of the total number of these groups are alkyl groups having 1 to 8 carbon atoms or phenyl groups. In terms of ease of production and compatibility with the above-mentioned preferred components (A) and (B), the other organic groups are preferably methyl groups or phenyl groups.

[0040] Specific examples of component (C) include tris(dimethylhydrogensiloxy)methylsilane, tetra(dimethylhydrogensiloxy)silane, methylhydrogenpolysiloxane capped at both ends with trimethylsiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymer capped at both ends with trimethylsiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymer capped at both ends with dimethylhydrogensiloxane, cyclic methylhydrogenoligosiloxane, cyclic methylhydrogensiloxane-dimethylsiloxane copolymer, methylhydrogensiloxane-diphenylsiloxane copolymer capped at both molecular chain ends with trimethylsiloxy groups, methylhydrogensiloxane-diphenylsiloxane-dimethylsiloxane copolymer capped at both molecular chain ends with trimethylsiloxy groups, hydrolysis condensate of trimethoxysilane, (CH3)2HSiO 1 / 2 Units and SiO 4 / 2A copolymer consisting of (CH3)2HSiO units. 1 / 2 Units and SiO 4 / 2 Units and (C6H5)SiO 3 / 2 A copolymer consisting of (CH3)2HSiO units. 1 / 2 Units and CH3SiO 3 / 2 units, and mixtures of two or more of these.

[0041] [SiH / Vi ratio] The composition of the present invention is hydrosilylation reaction-curable, and there are no particular limitations on the amount of component (C) used so long as the composition can be sufficiently cured by a hydrosilylation reaction; however, the molar ratio of the amount of silicon-bonded hydrogen atom (SiH) groups in component (C) to the sum of the amount (amount of substance) of alkenyl groups in component (A) and the amount (amount of substance) of alkenyl groups in component (B) in the composition is preferably in the range of 0.1 to 100, and may also be in the range of 0.5 to 60, 1.0 to 50, or 1.0 to 40.

[0042] On the other hand, for the purpose of improving adhesion to a substrate such as glass, the amount of SiH groups can be designed to be 10 or more, or 20 or more, and preferably exceeds 20, more preferably 22 or more. For example, the amount of silicon-bonded hydrogen atoms (SiH) groups in the component (C) relative to the sum of the amount (amount of substance) of alkenyl groups in the component (A) and the amount (amount of substance) of alkenyl groups in the component (B) in the composition can be designed to be in the range of 20 to 60, or in the range of 22 to 50. If the amount of SiH groups is below the lower limit, the technical effect of improving adhesion to the substrate may not be realized. On the other hand, if the amount of SiH groups exceeds the upper limit, the amount of curing agent remaining without reacting increases, which may cause adverse effects on the cured physical properties such as brittleness of the cured product, or problems such as gas generation. However, even if the SiH / Vi ratio of the composition is outside the above range, a pressure-sensitive adhesive layer sufficient for practical use can be formed.

[0043] When alkenyl-containing cyclic siloxanes and organosilicon compounds other than components (A) and (B) are optionally used, from the viewpoint of the curability of the composition of the present invention, the amount of silicon-bonded hydrogen (SiH) groups in component (C) relative to the total amount (amount of substance) of alkenyl groups in the composition including these components is preferably 1.0 or more, and the amount of silicon-bonded hydrogen (SiH) groups in component (C) relative to the total amount (amount of substance) of alkenyl groups in the composition may be in the range of 1.5 to 60, or may be in the range of 20 to 60.

[0044] [Hydrosilylation reaction catalyst] The organopolysiloxane composition according to the present invention contains a hydrosilylation reaction catalyst. Examples of the hydrosilylation reaction catalyst include platinum-based catalysts, rhodium-based catalysts, and palladium-based catalysts. Platinum-based catalysts are preferred because they can significantly accelerate the curing of the composition. As the platinum-based catalyst, platinum-alkenylsiloxane complexes are preferred, and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane is particularly preferred because the platinum-alkenylsiloxane complexes have good stability. In addition, non-platinum metal catalysts such as iron, ruthenium, and iron / cobalt may also be used as catalysts for accelerating the hydrosilylation reaction.

[0045] In the present invention, the content of the hydrosilylation reaction catalyst is not particularly limited, but the platinum metal content is in the range of 0.1 to 200 ppm, may be in the range of 0.1 to 150 ppm, may be in the range of 0.1 to 100 ppm, or may be in the range of 0.1 to 50 ppm, relative to the total amount of solids in the composition. Here, the platinum metal is a metal element of Group VIII consisting of platinum, rhodium, palladium, ruthenium, and iridium, and in practical use, the content of the platinum metal excluding the ligand of the hydrosilylation reaction catalyst is preferably in the above range. Note that the solid content refers to the components (mainly the base agent, adhesion imparting component, crosslinking agent, catalyst, and other non-volatile components) that form a cured layer when the organopolysiloxane composition according to the present invention is cured, and does not include volatile components such as solvents that volatilize during heat curing.

[0046] When the content of platinum-based metal in the organopolysiloxane composition according to the present invention is 50 ppm or less (45 ppm or less, 35 ppm or less, 30 ppm or less, 25 ppm or less, or 20 ppm or less), discoloration or coloring of the transparent pressure-sensitive adhesive layer may be particularly suppressed after curing or when exposed to high-energy rays such as heating or ultraviolet light. On the other hand, from the viewpoint of the curability of the organopolysiloxane composition, the content of platinum-based metal is 0.1 ppm or more, and if it is below this lower limit, it may cause poor curing.

[0047] Component (E) is a cure retarder that is added to inhibit the crosslinking reaction between the alkenyl groups in the composition and the SiH groups in component (C), thereby extending the pot life at room temperature and improving storage stability. Therefore, from a practical standpoint, it is a nearly essential component for the pressure-sensitive adhesive layer-forming organopolysiloxane composition of the present invention.

[0048] Specifically, the (E) component can be exemplified by acetylene compounds, enyne compounds, organic nitrogen compounds, organic phosphorus compounds, and oxime compounds.Specifically, the (E) component can be exemplified by alkyne alcohols such as 3-methyl-1-butyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, 3-methyl-1-pentyn-3-ol, 1-ethynyl-1-cyclohexanol, and phenylbutynol; enyne compounds such as 3-methyl-3-penten-1-yne and 3,5-dimethyl-1-hexyn-3-yne; 2-ethynyl-4-methyl-2-pentene, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, and 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane, and methylalkenylcyclosiloxane; and benzotriazole.

[0049] From the viewpoint of the curing behavior of the composition, it is preferable that the pressure-sensitive adhesive layer-forming organopolysiloxane composition of the present invention has a viscosity increase of no more than 1.5 times 8 hours after preparation at room temperature and is curable at 80 to 200°C. Suppression of viscosity increase is important from the viewpoints of handling, pot life, and post-curing properties, because even if a large excess of component (C) is contained and the platinum-based metal content is optionally low, curability can be ensured by curing at a certain high temperature (80 to 200°C) or higher. Note that such a composition can be realized by selecting a suitable combination and blending amount of each of the above components, the hydrosilylation catalyst, and component (E) as described above.

[0050] The organopolysiloxane composition according to the present invention may contain an organic solvent as a solvent in addition to the above-mentioned preferred components (A) and (B). The type and amount of the organic solvent are adjusted in consideration of coating workability and the like. Examples of the organic solvent include aromatic hydrocarbon solvents such as toluene, xylene, and benzene, aliphatic hydrocarbon solvents such as heptane, hexane, octane, and isoparaffin, ester solvents such as ethyl acetate and isobutyl acetate, ether solvents such as diisopropyl ether and 1,4-dioxane, chlorinated aliphatic hydrocarbon solvents such as trichloroethylene, perchloroethylene, and methylene chloride, and solvent volatile oils, and two or more of them may be combined depending on the wettability of the sheet-like substrate. The amount of the organic solvent to be added is preferably an amount that allows the mixture of components (A) to (C) to be uniformly applied to the surface of the sheet-like substrate, for example, 5 to 3,000 parts by mass per 100 parts by mass of the total of components (A), (B), and (C).

[0051] The organopolysiloxane composition of the present invention may optionally contain components other than the above-mentioned components, provided that the technical effects of the present invention are not impaired. For example, the composition may contain an adhesion promoter; a non-reactive organopolysiloxane such as polydimethylsiloxane or polydimethyldiphenylsiloxane; an antioxidant; a light stabilizer; a flame retardant; and one or more types of antistatic agents. In addition to these components, pigments, dyes, inorganic fine particles (reinforcing fillers, dielectric fillers, conductive fillers, thermally conductive fillers), etc. may also be optionally blended.

[0052] [(A') A chain organopolysiloxane that does not contain a carbon-carbon double bond-containing reactive group in the molecule] The organopolysiloxane composition of the present invention may contain a non-reactive organopolysiloxane such as polydimethylsiloxane or polydimethyldiphenylsiloxane that does not contain a carbon-carbon double bond-containing reactive group such as an alkenyl group, an acrylic group, or a methacrylic group, which may improve the loss factor (tan δ), storage modulus (G'), and loss modulus (G'') of the pressure-sensitive adhesive layer described below. For example, the loss factor of the pressure-sensitive adhesive layer can be increased by using polydimethylsiloxane having a hydroxyl group terminal, or polydimethylsiloxane or polydimethyldiphenylsiloxane having a trimethylsiloxy terminal, and such compositions are within the scope of the present invention.

[0053] Here, the (A') component is a linear organopolysiloxane that does not participate in the curing reaction by hydrosilylation, and the mass ratio of the (B) component in the composition can affect the properties of the composition, such as adhesive strength and storage modulus. As described above, the mass ratio of the (B) component to the (A) and (A') components may be in the range of 1.4 to 4.0, and in order to achieve the desired adhesive strength and storage modulus, the range of 1.9 to 3.5 is particularly preferred. The mass ratio of the (A) component to the (A') component is not particularly limited, but may be designed to be in the range of 100:0 to 60:40, 100:0 to 65:35, 90:10 to 65:35, 85:15 to 70:30, etc., depending on the desired storage modulus and mass ratio of the (B) component.

[0054] The method for preparing the organopolysiloxane composition of the present invention is not particularly limited, and the composition is prepared by mixing the components homogeneously. If necessary, a solvent may be added, and the components may be mixed at a temperature of 0 to 200°C using a known stirrer or kneader.

[0055] The organopolysiloxane composition of the present invention is applied onto a substrate to form a coating film, and then heated at a temperature of 80 to 200° C., preferably at a temperature of 90 to 190° C., to form a cured product. Examples of the coating method include gravure coating, offset coating, offset gravure, roll coating, reverse roll coating, air knife coating, curtain coating, and comma coating. The amount of coating can be designed to a desired thickness depending on the application, such as a display device. For example, the thickness of the pressure-sensitive adhesive layer after curing is 1 to 1,000 μm, may be 5 to 900 μm, or may be 10 to 800 μm, but is not limited thereto.

[0056] [Pressure-sensitive adhesive and adhesion range] The organopolysiloxane composition of the present invention is characterized in that the cured layer obtained by curing the composition by a hydrosilylation reaction has pressure-sensitive adhesive properties. The pressure-sensitive adhesive layer of the present invention has the above-mentioned configuration and exhibits high adhesive strength to substrates, so that it can be used as a replacement for known silicone pressure-sensitive adhesives, if desired.

[0057] Specifically, the adhesive strength of a 50 μm thick pressure-sensitive adhesive layer obtained by curing the organopolysiloxane composition of the present invention, measured against a 2 mm thick polymethyl methacrylate sheet at a tensile speed of 300 mm / min using a 180° peel test method according to JIS Z 0237, is in the range of 2000 gf / inch or more, preferably 2200 gf / inch or more, and in particular, a pressure-sensitive adhesive layer in the range of 2000 to 4000 gf / inch can be designed, with a pressure-sensitive adhesive layer in the range of 2200 to 3500 gf / inch being preferred. Note that the above thickness (50 μm) is the thickness of the cured layer itself, which is the standard for objectively defining the adhesive strength of the cured layer according to the present invention, and it goes without saying that the organopolysiloxane composition of the present invention can be used as a cured layer or pressure-sensitive adhesive layer of any thickness, not limited to a thickness of 50 μm.

[0058] [Storage modulus and other mechanical properties] The pressure-sensitive adhesive layer-forming organopolysiloxane composition of the present invention is such that the pressure-sensitive adhesive layer obtained by curing has a shear storage modulus G' at 25°C of 3.5 MPa or more, preferably in the range of 3.5 to 20 MPa, and those having a storage modulus G' in the range of 3.5 to 17.5 MPa are preferably included in the scope of the present invention.

[0059] Furthermore, the pressure-sensitive adhesive layer obtained by curing the composition of the present invention has a stress at 500% strain at 25°C of 0.25 MPa or more, preferably in the range of 0.25 to 3.0 MPa, and those having a stress in the range of 0.27 to 2.5 MPa are preferably included in the scope of the present invention.

[0060] Since the organopolysiloxane composition capable of forming a pressure-sensitive adhesive layer of the present invention has such a storage modulus G' and tensile stress at room temperature, and also has the above-mentioned high adhesive strength, it is suitable for use in forming elastic adhesive members, as members of electronic devices and electrical equipment such as speakers and transducers, as well as for application in the field of advanced electronic materials and display elements such as smart devices.

[0061] The storage modulus (G') of the pressure-sensitive adhesive layer according to the present invention can be measured by a known measurement method. For example, the storage modulus (G') can be measured using an MCR301 viscoelasticity measuring device (manufactured by Anton Paar), and can be measured using a disk-shaped sample with a diameter of 8 mm and a thickness of about 0.5 to 1 mm, with 8 mm parallel plates, a frequency of 1 Hz, a strain of 0.1%, and a heating rate of 3°C / min, in the range of -70°C to 250°C, and can be measured as a value at 25°C.

[0062] The pressure-sensitive adhesive layer according to the present invention may have a storage modulus G' at 1.0 Hz at -20°C that is at least three times the storage modulus G' at 1.0 Hz at 25°C.

[0063] [Transparency, color tone, or color-changing properties of pressure-sensitive adhesive layer] The organopolysiloxane composition of the present invention may be substantially transparent, translucent or opaque, and the transparency can be designed according to the application of the pressure-sensitive adhesive layer. When it is transparent to the naked eye, more objectively, the transmittance of light at a wavelength of 450 nm of the pressure-sensitive adhesive layer for a display device, which is made of a cured layer having a thickness of 100 μm, is 80% or more, preferably 90% or more, and may be designed to be 95% or more, assuming that the value of air is 100%. On the other hand, in the case of bonding electric and electronic parts that do not require light transmittance, the pressure-sensitive adhesive layer may be translucent to opaque, and filler components or additives that impair colorability or light transmittance may be used according to required properties other than light transmittance.

[0064] The organopolysiloxane composition of the present invention can be designed so that the cured product is not colored in addition to the above-mentioned transparency by optionally reducing the content of platinum-based metals in the cured layer, etc. Furthermore, the cured layer of the present invention can be designed so that its color tone does not change significantly, and in particular so that the problem of yellowing does not occur, even when exposed to high temperatures or high-energy rays such as ultraviolet rays for a long period of time.

[0065] [Use as a pressure-sensitive adhesive layer] The cured product of the present invention can be used as a pressure-sensitive adhesive layer in particular. In addition, in order to improve adhesion to an adherend, the surface of the pressure-sensitive adhesive layer or the substrate may be subjected to surface treatment such as primer treatment, corona treatment, etching treatment, plasma treatment, etc. However, since the pressure-sensitive adhesive layer of the present invention has excellent adhesion to substrates such as display devices as described above, these steps may be added as necessary to further improve adhesion to the adherend, and these steps may be omitted to achieve higher production efficiency.

[0066] The curable organopolysiloxane composition according to the present invention can be applied to a release liner, cured by heating under the above-mentioned temperature conditions, and the release liner can be peeled off and the composition can be attached to a film-like substrate, a tape-like substrate, or a sheet-like substrate (hereinafter referred to as a "film-like substrate"), or the composition can be applied to a film-like substrate and cured by heating under the above-mentioned temperature conditions to form a pressure-sensitive adhesive layer on the surface of the substrate. A laminate having a cured layer, particularly a film-like pressure-sensitive adhesive layer, formed by curing the organopolysiloxane composition according to the present invention on these film-like substrates can be used for adhesive tapes, bandages, low-temperature supports, transfer films, labels, emblems, and decorative or explanatory signs. Furthermore, the cured layer formed by curing the organopolysiloxane composition according to the present invention can be used in the assembly of automobile parts, toys, electronic circuits, or keyboards. Alternatively, the cured layer formed by curing the organopolysiloxane composition according to the present invention, particularly a film-like pressure-sensitive adhesive layer, can be used in the construction and use of laminated touch screens or flat panel displays. The surface of the film substrate opposite the pressure-sensitive adhesive layer may be subjected to a surface treatment such as treatment to prevent scratches, stains, fingerprints, glare, reflection, or static electricity.

[0067] Examples of substrate types include paperboard, corrugated cardboard, clay-coated paper, polyolefin-laminated paper, especially polyethylene-laminated paper, synthetic resin films and sheets, natural fiber fabrics, synthetic fiber fabrics, artificial leather fabrics, and metal foils.

[0068] The substrate is preferably in the form of a film or sheet. Its thickness is not particularly limited and can be designed to a desired thickness depending on the application. Furthermore, in order to improve the adhesion between the support film and the pressure-sensitive adhesive layer, a support film that has been subjected to a primer treatment, a corona treatment, an etching treatment, or a plasma treatment may be used. In addition, the surface opposite to the pressure-sensitive adhesive layer of the film-like substrate may be surface-treated, such as to prevent scratches, to prevent dirt, to prevent fingerprints, to prevent glare, to prevent reflection, or to prevent static electricity.

[0069] The pressure-sensitive adhesive layer according to the present invention may be a single layer or a multilayer formed by laminating two or more pressure-sensitive adhesive layers depending on the required properties. The multilayer pressure-sensitive adhesive layer may be formed by laminating pressure-sensitive adhesive films prepared one by one, or a process of applying and curing a pressure-sensitive adhesive layer-forming organopolysiloxane composition onto a film substrate provided with a release layer may be carried out multiple times.

[0070] The pressure-sensitive adhesive layer according to the present invention may be given the role of other functional layers selected from a dielectric layer, a conductive layer, a heat dissipation layer, an insulating layer, a reinforcing layer, etc., in addition to the adhesive or cohesive function between members.

[0071] When the cured layer obtained by curing the organopolysiloxane composition of the present invention is a pressure-sensitive adhesive layer, particularly a pressure-sensitive adhesive film, it is preferable to handle the cured layer as a laminate film that is peelably attached to a film substrate having a release layer with release coating ability.The release layer may be a release layer having release coating ability such as a silicone-based release agent, a fluorine-based release agent, an alkyd-based release agent, or a fluorosilicone-based release agent, or the substrate itself that forms physically fine irregularities on the substrate surface or is difficult to adhere to the pressure-sensitive adhesive layer of the present invention, and it is preferable to use a release layer obtained by curing a fluorosilicone-based release agent.In addition, in the laminate, the release layer may be a differential release layer that is a first release layer and a second release layer that are different in type and release force of the release agent that constitutes the release layer, and the fluorosilicone-based release agent may be a curing reactive silicone composition that contains one or more fluorine-containing groups selected from a fluoroalkyl group and a perfluoropolyether group.

[0072] The cured product obtained by curing the organopolysiloxane composition of the present invention has both the above-mentioned viscoelasticity and adhesive strength, and is therefore useful as an elastic adhesive member for various electronic devices or electrical devices. In particular, it is useful as an electronic material, a display device member, or a transducer member (including sensors, speakers, actuators, and generators), and the preferred use of the cured product is as a member of an electronic component or a display device. The cured product of the present invention may be transparent or opaque, but a film-shaped cured product, particularly a substantially transparent pressure-sensitive adhesive film, is suitable as a member for a display panel or display, and is particularly useful for so-called touch panel applications in which devices, particularly electronic devices, can be operated by touching the screen with fingertips or the like. In addition, the opaque elastic adhesive layer is particularly useful for applications as film- or sheet-shaped members used in sensors, speakers, actuators, etc., which do not require transparency and require a certain degree of stretchability or flexibility in the adhesive layer itself.

[0073] In particular, a pressure-sensitive adhesive layer obtained by curing the organopolysiloxane composition of the present invention can achieve pressure-sensitive adhesive properties equivalent to those of conventional silicone pressure-sensitive adhesive layers, and can improve adhesion to substrates such as display devices without causing problems of poor curing or reduced curing properties.

[0074] [Display panel or display components] The cured product obtained by curing the organopolysiloxane composition of the present invention can be used in the construction and use of a laminated touch screen or flat panel display, and the specific method of use thereof can be any known method for using a pressure-sensitive adhesive layer (particularly a silicone PSA) without any particular limitation.

[0075] For example, a cured product obtained by curing the organopolysiloxane composition of the present invention can be used in the manufacture of a display device such as a touch panel as an optically transparent silicone-based pressure-sensitive adhesive film or pressure-sensitive adhesive layer disclosed in the above-mentioned JP-T 2014-522436 or JP-T 2013-512326, etc. In addition, a cured product obtained by curing the organopolysiloxane composition of the present invention may be used as an adhesive film for a polarizing plate used in the manufacture of a display device such as a touch panel, or as a pressure-sensitive adhesive layer used for bonding between a touch panel and a display module as described in JP-A 2013-065009. [Industrial Applicability]

[0076] The curing reactive organopolysiloxane composition of the present invention and the cured product obtained by curing the composition are not limited to the above-mentioned uses, and the pressure-sensitive adhesive film comprising the cured product obtained by curing the composition can be used in various display devices for displaying characters, symbols, and images. The surface shape of such a display device may be curved or curved rather than flat, and examples thereof include curved displays or curved transmission screens used in automobiles (including electric automobiles) and aircraft, as well as various flat panel displays (FPDs). Furthermore, these display devices can display icons for executing functions or programs on the screen or display, notification displays such as e-mail and programs, and operation buttons for various devices such as car navigation devices, audio devices, and air conditioners, and may be provided with a touch panel function that allows input operations by touching these icons, notification displays, and operation buttons with a finger. Furthermore, the cured product obtained by curing the composition has excellent adhesiveness and viscoelastic properties, and can therefore be used as a film or sheet-like member that is a transducer member (including those for sensors, speakers, actuators, and generators) such as a membrane for a speaker, and can also be used as a sealing layer or adhesive layer for a secondary battery, a fuel cell, or a solar cell module.

[0077] In addition, JP 2017-047767 A, JP 2014-182335 A, JP 2014-063064 A, JP 2013-233852 A, and the like disclose vehicle display devices having a curved display surface, and the pressure-sensitive adhesive layer of the present invention can be suitably applied or replaced as part or all of the adhesive layer or pressure-sensitive adhesive layer in these documents that require transparency. EXAMPLES

[0078] Examples and Comparative Examples of the present invention are described below. In each Example, Comparative Example, and Reference Example, "cured" means that each composition was completely cured under each curing condition.

[0079] (Preparation of Curable Reactive Organopolysiloxane Composition) The curable organopolysiloxane compositions shown in the Examples, Comparative Examples, and Reference Examples were prepared using the components shown in Table 1. Note that all % in Table 1 is by mass %.

[0080] (Measurement of molecular weight of organopolysiloxane component) The weight average molecular weight (Mw) and number average molecular weight (Mn) of organopolysiloxane components such as organopolysiloxane resins were determined in terms of standard polystyrene using a Waters gel permeation chromatography (GPC) with tetrahydrofuran (THF) as a solvent. (Measurement of hydroxyl (OH) content in organopolysiloxane resin) Bruker ACP-300 with glass-free probe 29 Using a Si NMR spectrometer, the chemical shift of Si(OH)O appears at -93 to -103.5 ppm when the chemical shift of tetramethylsilane is set at 0 ppm. 2 / 3 The molar content was calculated from the ratio of the units to the total silicon, and was then converted into the mass% of hydroxyl groups (OH) in the organopolysiloxane resin. Note that the organopolysiloxane resins in the following examples did not contain any hydrolyzable functional groups other than hydroxyl groups. (Adhesive strength measurement) Each composition was applied to a PET film (manufactured by Toray Industries, Inc., product name Lumirror (registered trademark) S10, thickness 50 μm) so that the thickness after curing was 50 μm, and cured at 150 ° C for 3 minutes. After leaving it for 1 day, the sample was cut to a width of 20 mm, and the adhesive layer surface was attached to a PMMA plate (manufactured by Paltec, Acrylite L001, 50 x 120 x 2 mm) using a roller to prepare a test piece. The test piece using the PMMA plate was measured for adhesive strength (measurement at a width of 20 mm was converted to gf / inch) using a 180 ° peel test method according to JIS Z0237 using an Orientec RTC-1210 tensile tester at a tensile speed of 300 mm / min. (Dynamic viscoelasticity: storage modulus G' at 25℃) Each composition was applied to a release liner coated with a fluorosilicone release coating so that the thickness after curing was about 100 μm, and cured at 150 ° C for 3 minutes. Five or more sheets of this pressure-sensitive adhesive film were stacked to obtain a film sample with a thickness of 500 μm or more, sandwiched between release liners on both sides. The film was cut out to a diameter of 8 mm and attached to a parallel plate probe of a dynamic viscoelasticity device (Made by Anoton Paar, MCR301) to measure the storage modulus G'. The measurement conditions were in the range of -70 ° C to 250 ° C, a frequency of 1 Hz, and a heating rate of 3 ° C / min. The loss factor, storage modulus G', and loss modulus G'' were measured, and the storage modulus G' at 25 ° C was recorded (unit: MPa). (Tensile test) A film sample with a thickness of 500 μm or more, sandwiched between release liners on both sides, obtained in the same manner as the above dynamic viscoelasticity test sample, was cut to a width of approximately 5 mm and a length of approximately 70 mm, and the release liner was peeled off while applying baby powder to the adhesive surface to prepare a tensile test sample. The tensile test was performed using Shimadzu Autograph AGS-X, holding the sample at approximately 25 mm above and below, at a speed of 300 mm / min. The stress and strain were determined for each sample from the exact sample width, thickness, and crosshead distance, and the stress at 500% strain was recorded (unit: MPa).

[0081] The materials of the curable reactive organopolysiloxane composition are shown in Table 1. The viscosity or plasticity of each component was measured at room temperature by the following method. [viscosity] Viscosity (mPa s) is a value measured using a rotational viscometer conforming to JIS K7117-1, and kinematic viscosity (mm 2 / s) is a value measured using an Ubbelohde viscometer conforming to JIS Z8803. [Plasticity] The plasticity was measured according to the method specified in JIS K 6249 (a 4.2 g spherical sample was subjected to a load of 1 kgf for 3 minutes at 25°C, the thickness was read to the nearest 1 / 100 mm, and this value was multiplied by 100).

[0082] Table 1. Components of the curable organopolysiloxane composition [Table 1]

[0083] [Examples 1 to 7, Comparative Examples 1 to 5] The compositions of the following Examples 1 to 7 and Comparative Examples 1 to 5 were cured by the above-mentioned method, and the adhesive strength to the PMMA plate, viscoelasticity, and stress-strain were measured by the above-mentioned methods. The evaluation results are shown in Table 2. Example 1 32.3 parts by weight of vinyl-functional polydimethylsiloxane of component a1, 100.8 parts by weight of MQ silicone resin of component b1, 4.3 parts by weight of MQ silicone resin of component b2, 84.9 parts by weight of toluene, 0.287 parts by weight of methylhydrogenpolysiloxane of component c2, 0.409 parts by weight of 20% solution of cure retarder of component e were mixed well at room temperature, and 0.355 parts by weight of platinum-based hydrosilylation reaction catalyst of component d was added to the mixture to obtain a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of SiH group in component c2 to the amount of alkenyl group in component a1 was 29.2, and the content of platinum metal in the solid content was 22 ppm.

[0084] Example 2 30.3 parts by weight of vinyl-functional polydimethylsiloxane of component a1, 99.4 parts by weight of MQ silicone resin of component b1, 8.0 parts by weight of MQ silicone resin of component b2, 84.4 parts by weight of toluene, 0.274 parts by weight of methylhydrogenpolysiloxane of component c2, 0.409 parts by weight of 20% solution of cure retarder of component e were mixed well at room temperature, and 0.355 parts by weight of platinum-based hydrosilylation reaction catalyst of component d was added to the mixture to obtain a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of SiH group in component c2 to the amount of alkenyl group in component a1 was 29.6, and the content of platinum metal in the solid content was 22 ppm.

[0085] Example 3 30.3 parts by weight of vinyl-functional polydimethylsiloxane of component a1, 97.1 parts by weight of MQ silicone resin of component b1, 10.0 parts by weight of MQ silicone resin of component b2, 84.8 parts by weight of toluene, 0.274 parts by weight of methylhydrogenpolysiloxane of component c2, 0.409 parts by weight of 20% solution of cure retarder of component e were mixed well at room temperature, and 0.355 parts by weight of platinum-based hydrosilylation reaction catalyst of component d was added to the mixture to obtain a curing reactive organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of SiH group in component c2 to the amount of alkenyl group in component a1 was 29.6, and the content of platinum metal in the solid content was 22 ppm.

[0086] Example 4 32.3 parts by weight of vinyl-functional polydimethylsiloxane of component a3, 100.8 parts by weight of MQ silicone resin of component b1, 4.3 parts by weight of MQ silicone resin of component b2, 84.9 parts by weight of toluene, 0.266 parts by weight of methylhydrogenpolysiloxane of component c2, 0.491 parts by weight of 20% solution of cure retarder of component e were mixed well at room temperature, and 0.355 parts by weight of platinum-based hydrosilylation reaction catalyst of component d was added to the mixture to obtain a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of SiH group in component c2 to the amount of alkenyl group in component a3 was 5.40, and the content of platinum metal in the solid content was 22 ppm.

[0087] Example 5 30.3 parts by weight of vinyl-functional polydimethylsiloxane of component a3, 99.4 parts by weight of MQ silicone resin of component b1, 8.0 parts by weight of MQ silicone resin of component b2, 84.4 parts by weight of toluene, 0.249 parts by weight of methylhydrogenpolysiloxane of component c2, 0.491 parts by weight of 20% solution of cure retarder of component e were mixed well at room temperature, and 0.355 parts by weight of platinum-based hydrosilylation reaction catalyst of component d was added to the mixture to obtain a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of SiH group in component c2 to the amount of alkenyl group in component a3 was 5.40, and the content of platinum metal in the solid content was 22 ppm.

[0088] Example 6 30.3 parts by weight of vinyl-functional polydimethylsiloxane of component a3, 97.1 parts by weight of MQ silicone resin of component b1, 10.0 parts by weight of MQ silicone resin of component b2, 84.8 parts by weight of toluene, 0.249 parts by weight of methylhydrogenpolysiloxane of component c2, 0.491 parts by weight of 20% solution of cure retarder of component e were mixed well at room temperature, and 0.355 parts by weight of platinum-based hydrosilylation reaction catalyst of component d was added to the mixture to obtain a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of SiH group in component c2 to the amount of alkenyl group in component a3 was 5.40, and the content of platinum metal in the solid content was 22 ppm.

[0089] Example 7 32.3 parts by weight of vinyl-functional polydimethylsiloxane of component a3, 100.8 parts by weight of MQ silicone resin of component b1, 4.3 parts by weight of MQ silicone resin of component b2, 29.3 parts by weight of toluene, 0.629 parts by weight of methylhydrogenpolysiloxane of component c2, 0.491 parts by weight of 20% solution of cure retarder of component e were mixed well at room temperature, and 0.355 parts by weight of platinum-based hydrosilylation reaction catalyst of component d was added to the mixture to obtain a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of SiH group in component c2 to the amount of alkenyl group in component a3 was 12.8, and the content of platinum metal in the solid content was 22 ppm.

[0090] Comparative Example 1 36.2 parts by weight of vinyl-functional polydimethylsiloxane of component a2, 99.6 parts by weight of MQ silicone resin of component b1, 30.8 parts by weight of toluene, 0.332 parts by weight of methylhydrogenpolysiloxane of component c2, and 0.71 parts by weight of 20% solution of cure retarder of component e were mixed well at room temperature, and 0.645 parts by weight of platinum-based hydrosilylation reaction catalyst of component d was added to the mixture to obtain a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of SiH group in component c2 to the amount of alkenyl group in component a2 was 23.0, and the content of platinum metal in the solid content was 40 ppm.

[0091] Comparative Example 2 43.1 parts by weight of vinyl-functional polydimethylsiloxane of component a2, 88.9 parts by weight of MQ silicone resin of component b1, 34.7 parts by weight of toluene, 0.434 parts by weight of methylhydrogenpolysiloxane of component c2, and 0.75 parts by weight of 20% solution of cure retarder of component e were mixed well at room temperature, and 0.645 parts by weight of platinum-based hydrosilylation reaction catalyst of component d was added to the mixture to obtain a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of SiH groups in component c2 to the amount of alkenyl groups in component a2 was 25.3, and the content of platinum metal relative to the solid content was 40 ppm.

[0092] Comparative Example 3 50.0 parts by weight of vinyl-functional polydimethylsiloxane of component a2, 78.1 parts by weight of MQ silicone resin of component b1, 38.5 parts by weight of toluene, 0.350 parts by weight of methylhydrogenpolysiloxane of component c2, and 0.75 parts by weight of 20% solution of cure retarder of component e were mixed well at room temperature, and 0.645 parts by weight of platinum-based hydrosilylation reaction catalyst of component d was added to the mixture to obtain a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of SiH groups in component c2 to the amount of alkenyl groups in component a2 was 17.6, and the content of platinum metal relative to the solid content was 40 ppm.

[0093] Comparative Example 4 36.4 parts by weight of vinyl-functional polydimethylsiloxane of component a1, 100.0 parts by weight of MQ silicone resin of component b1, 86.1 parts by weight of toluene, 0.737 parts by weight of methylhydrogenpolysiloxane of component c1, and 0.577 parts by weight of 20% solution of cure retarder of component e were mixed well at room temperature, and 0.484 parts by weight of platinum-based hydrosilylation reaction catalyst of component d was added to the mixture to obtain a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of SiH groups in component c1 to the amount of alkenyl groups in component a1 was 30.7, and the content of platinum metal in the solid content was 30 ppm.

[0094] Comparative Example 5 48.3 parts by weight of vinyl-functional polydimethylsiloxane of component a1, 81.3 parts by weight of MQ silicone resin of component b1, 92.9 parts by weight of toluene, 0.910 parts by weight of methylhydrogenpolysiloxane of component c1, and 0.577 parts by weight of 20% solution of cure retarder of component e were mixed well at room temperature, and 0.484 parts by weight of platinum-based hydrosilylation reaction catalyst of component d was added to the mixture to obtain a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of SiH groups in component c1 to the amount of alkenyl groups in component a1 was 28.6, and the content of platinum metal relative to the solid content was 30 ppm.

[0095] [Table 2]

[0096] As shown in Table 2, the pressure-sensitive adhesive layer-forming organopolysiloxane compositions of Examples 1 to 7 had a mass ratio of the linear organopolysiloxane to the organopolysiloxane resin within the range specified in the present invention, and used a specified organopolysiloxane resin mixture, but had sufficient curability, a storage modulus G' at 25°C of 3.5 MPa or more, a tensile stress at 500% strain of 0.25 MPa or more, and an adhesive strength of 2000 gf / inch or more. From these results, the pressure-sensitive adhesive layer-forming organopolysiloxane compositions of these Examples have a high storage modulus and tensile stress, and have strong adhesive strength to the substrate.

[0097] On the other hand, in Comparative Examples 1 to 5, which do not use a specific organopolysiloxane resin mixture, the shear storage modulus G' at 25°C is less than 3.5 MPa, and the tensile stress at 500% strain is less than 0.25 MPa, so that the object of the present invention could not be achieved. In Comparative Examples 1 and 4, the mass ratios of the linear organopolysiloxane and the organopolysiloxane resin are 1.75 and 1.76, respectively, and the adhesive strength of the resulting pressure-sensitive adhesive layer is 2000 gf / inch or more, but the shear storage modulus G' and the tensile stress at 500% strain are insufficient. That is, within the range of the composition of the prior art, there is a trade-off relationship between the shear storage modulus G' and the tensile stress at 500% strain and the adhesive strength, and it was not possible to realize a pressure-sensitive adhesive layer that achieves both of these.

Claims

1. (A) a linear organopolysiloxane having an average of more than one alkenyl group per molecule, at least a part of which is (A1) a crude rubber-like alkenyl-group-containing organopolysiloxane having a viscosity of 100,000 mPa·s or more at 25° C. or a plasticity of 50 to 200 as measured in accordance with the method specified in JIS K6249, the content of vinyl (CH 2 ═CH) moieties in the alkenyl groups being in the range of 0.005 to 0.400 mass %, (B) An organopolysiloxane resin mixture containing the following components (b1) and (b2) in a mass ratio of 15:85 to 99:1, the organopolysiloxane resin mixture being essentially composed of R 3 SiO 1 / 2 units (wherein R is a monovalent organic group and 90 mol % or more of R are alkyl groups or phenyl groups having 1 to 6 carbon atoms; M units) and SiO 4 / 2 units (Q units): (b1) an organopolysiloxane resin in which the sum of the content of hydroxyl groups and hydrolyzable groups relative to the total silicon atoms in the molecule is 9 mol % or less and the weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) relative to standard polystyrene is 4,500 or more; (b2) An organopolysiloxane resin in which the sum of the content of hydroxyl groups and hydrolyzable groups relative to the total silicon atoms in the molecule is 9 mol % or less, and the weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) relative to standard polystyrene is less than 4,500. (C) an organohydrogenpolysiloxane having at least two Si-H bonds in the molecule, the amount of which is such that the ratio (molar ratio) of the amount of substance of SiH groups in component (C) to the sum of the amounts of substances of alkenyl groups in components (A) and (B) is 0.1 to 100; (D) an effective amount of a hydrosilylation catalyst, the amount of which is in the range of 0.1 to 200 ppm of platinum-based metal in the solid content of the composition; and Optionally, (A') a linear organopolysiloxane that does not contain a carbon-carbon double bond-containing reactive group in the molecule. a mass ratio of component (B) to the sum of components (A) and (A') is in the range of 1.9 to 4.0, and a pressure-sensitive adhesive layer obtained by curing the composition has a shear storage modulus G' at 25°C of 3.5 MPa or more and a stress at 500% strain at 25°C of 0.25 MPa or more.

2. 2. The organopolysiloxane composition for forming a pressure-sensitive adhesive layer according to claim 1, wherein the adhesive strength of a 50 μm-thick pressure-sensitive adhesive layer obtained by curing the composition against a 2 mm-thick polymethyl methacrylate sheet is in the range of 2,000 gf / inch or more, as measured at a tensile speed of 300 mm / min using the 180° peel test method according to JIS Z 0237.

3. 3. The organopolysiloxane composition for forming a pressure-sensitive adhesive layer according to claim 1 or 2, characterized in that the mass ratio of component (B) to the sum of components (A) and (A') is in the range of 1.9 to 3.5, and the adhesive strength of a 50 μm-thick pressure-sensitive adhesive layer obtained by curing the composition against a 2 mm-thick polymethyl methacrylate sheet is in the range of 2,200 gf / inch or more, as measured using a 180° peel test method in accordance with JIS Z 0237 at a tensile speed of 300 mm / min.

4. Vinyl (CH) in the alkenyl group of component (A) ２ 4. The pressure-sensitive adhesive layer-forming organopolysiloxane composition according to claim 1, wherein the content of the =CH) moiety is within the range of 0.02 to 0.300 mass %.

5. 5. The organopolysiloxane composition capable of forming a pressure-sensitive adhesive layer according to claim 1, wherein the amount of component (C) is an amount such that the ratio (molar ratio) of the amount of substance of SiH groups in component (C) to the sum of the amounts of substances of alkenyl groups in components (A) and (B) is 20 to 60.

6. A pressure-sensitive adhesive layer obtained by curing the organopolysiloxane composition for forming a pressure-sensitive adhesive layer according to any one of claims 1 to 5.

7. A laminate comprising a film-like substrate and a pressure-sensitive adhesive layer formed by curing the organopolysiloxane composition capable of forming a pressure-sensitive adhesive layer according to any one of claims 1 to 5.

8. 8. The laminate of claim 7, wherein one or more film-like substrates are provided with a release layer for the pressure-sensitive adhesive layer.

9. 6. An elastic adhesive member obtained by curing the pressure-sensitive adhesive layer-forming organopolysiloxane composition according to any one of claims 1 to 5.

10. An electronic device or electrical device comprising the elastic adhesive member according to claim 9.

11. A speaker comprising the elastic adhesive member according to claim 9.

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