Composition for forming silicone-based adhesive layer and use thereof

Abstract

A composition for forming a silicone-based pressure sensitive adhesive layer, the composition comprising components (A) to (E): (A) a linear organopolysiloxane having an average number of greater than one alkenyl group per molecule; (B) an organopolysiloxane resin in which the total content of hydroxyl groups and hydrolysable groups is 2.0 mass% or less with respect to all silicon atoms in the molecule; (C) an organohydrogenpolysiloxane having at least two Si-H bonds in a molecule; (D) at least one of tetraalkoxysilane or a prepolymer thereof; and (E) a hydrosilylation reaction catalyst, in which the mass ratio of component (B) to component (A) is in the range of 0.5 to 3.5, and the amount of component (D) is in the range of 0.1 to 9.0 mass% based on the total mass of components (A) to (C). The composition for forming a silicone-based pressure-sensitive adhesive layer can form a pressure-sensitive adhesive layer having excellent curability due to a hydrosilylation reaction, improved adhesion, and lower Tg / modulus and softness properties at lower temperatures.

Description

[0001] Cross - reference to related applications

[0002] None. Technical field

[0003] The present invention relates to a curable reactive organopolysiloxane composition which forms a pressure - sensitive adhesive layer having a greater adhesive force (i.e., a composition for forming a silicone - based pressure - sensitive adhesive layer) by using at least one tetraalkoxysilane or a prepolymer of the tetraalkoxysilane as a fixing additive. In addition, the present invention relates to a pressure - sensitive adhesive composition using the composition and applications using the composition, such as laminates, electronic parts, or display devices (including flexible displays, foldable displays, automotive displays, and touch panels, etc.). Background art

[0004] Polysiloxane pressure - sensitive adhesive (PSA) compositions have excellent electrical insulation properties, heat resistance, cold resistance, and adhesion to various substrates and adherends compared to acrylic or rubber - based pressure - sensitive adhesive compositions, thus promoting their use in heat - resistant adhesive tapes, electrical insulation adhesive tapes, heat - seal tapes, electroplating masking tapes, etc. These polysiloxane pressure - sensitive adhesive compositions are classified into addition - reaction - curing type, condensation - reaction - curing type, peroxide - curing type, etc. according to their curing mechanisms. Addition - reaction - curing type pressure - sensitive adhesive compositions are widely used because these compositions cure rapidly at room temperature or when left standing by heating and do not produce any by - products.

[0005] Utilizing the above - mentioned characteristics of polysiloxane pressure - sensitive adhesive compositions and the characteristic that high transparency required thereof can be achieved, applications in advanced electronic materials and display elements such as the field of smart devices have been studied in recent years. Such devices adopt a structure in which a film composed of a plurality of layers including an electrode layer and a display layer is sandwiched between transparent substrates, and a polysiloxane pressure - sensitive adhesive composition having excellent heat resistance and cold resistance is expected to be effectively used for protecting the electrode layer and the display layer and improving the adhesion between these layers.

[0006] Specifically, in recent material development, there is a need for a polysiloxane pressure - sensitive adhesive composition having a relatively low storage elastic modulus (e.g., shear storage elastic modulus G') in a wide temperature range including low temperatures such as - 20°C, having excellent curability, and having sufficient adhesion for practical use. For example, various compositions for forming a silicone - based PSA (including optically clear adhesive (OCA)) layer and their applications have been proposed in Patent Documents 1 to 4. In these patent documents, silicone - based PSA layers having a low Tg and low modulus values at low temperatures have been proposed.

[0007] However, on the other hand, it has been found that such silicone-based PSA layers with a lower Tg and a lower modulus tend to have a lower adhesion. For this trade-off relationship between the adhesion in the silicone-based PSA layer and the low Tg / modulus, there is a potential problem that the silicone-based PSA layer cannot be applied to some applications in the assembly / adhesion layer or unit in laminates, electronic devices (such as displays), and articles where a strong adhesion is required.

[0008] On the other hand, hydrolyzable silanes are widely used in curable silicone compositions as crosslinking agents in condensation reaction-curable silicones or as silane coupling agents that are additives or treating agents for some components (see Patent Documents 5 to 8). However, there is no disclosure or suggestion of applying a specific tetraalkoxysilane in an addition reaction-curable silicone-based pressure-sensitive adhesive composition to enhance its adhesion.

[0009] Patent Documents 9 and 10 disclose addition reaction-curable silicone-based adhesive compositions, which may contain silanes such as vinyltriacetoxysilane and glycidoxypropyltrimethoxysilane. However, there is no disclosure or suggestion of applying a specific tetraalkoxysilane as an anchoring additive to enhance its adhesion. In addition, the curable PSA compositions disclosed in Patent Documents 9 and 10 cannot provide low Tg or low modulus properties in the cured PSA layer. Additionally, since the molar ratio of Si-H bonds to vinyl groups (i.e., SiH / Vi ratio) in the composition in Patent Document 9 is too low, the cured PSA layer tends to show cohesive failure with a low adhesion value. That is, there is no disclosure or substantial suggestion of selectively using a tetraalkoxysilane as an anchoring additive to solve the trade-off relationship between the adhesion and the low Tg / modulus in the silicone-based PSA layer.

[0010] Related technical literature

[0011] Patent Document

[0012] [Patent Document 1] WO2020032286A1

[0013] [Patent Document 2] WO2020032287A1

[0014] [Patent Document 3] WO2020032285A1

[0015] [Patent Document 4] WO2022138913A1

[0016] [Patent Document 5] US20100059171A1

[0017] [Patent Document 6] US20140356620A1

[0018] [Patent Document 7] JP2000017246A

[0019] [Patent Document 8] US5561203A

[0020] [Patent Document 9] WO2021000279A1

[0021] [Patent Document 10] WO2020248181A1 Summary of the Invention

[0022] Problems to be Solved

[0023] The present invention has been completed in order to solve the above problems, and an object thereof is to provide a curable reactive organopolysiloxane composition that forms a pressure-sensitive adhesive layer having improved and higher adhesiveness, having a low storage elastic modulus (G') / Tg property without impairing its curability. Another object of the present invention is to provide the use of the curable reactive organopolysiloxane composition or its cured product as a pressure-sensitive adhesive layer and their use as elastic adhesive members having improved adhesiveness in various applications, as well as devices and apparatuses provided with them.

[0024] Means for Solving the Problems

[0025] As a result of intensive studies on the problems described above, the present inventors have completed the present invention. That is, an object of the present invention is achieved by an organopolysiloxane composition that forms a pressure-sensitive adhesive layer and is curable by a specific hydrosilylation reaction, the composition containing at least one of tetraalkoxysilane or a prepolymer of the tetraalkoxysilane as an anchoring additive. Compared with the pressure-sensitive adhesive layer obtained from the same or similar composition but without the tetraalkoxysilane or its prepolymer as an anchoring additive, the pressure-sensitive adhesive layer of the present invention can exhibit an adhesiveness that is more than 20% greater. In addition, the tetraalkoxysilane as an anchoring additive does not impair the low Tg / modulus property in the silicone-based pressure-sensitive adhesive layer.

[0026] Specifically, the above-described problems can be solved by a composition for forming a silicone-based pressure-sensitive adhesive layer, the composition containing components (A) to (E):

[0027] (A) A linear organopolysiloxane having an average of more than 1 alkenyl group per molecule;

[0028] (B) An organopolysiloxane resin in which the total content of hydroxyl groups and hydrolyzable groups is 2.0 mass% or less relative to all silicon atoms in the molecule;

[0029] (C) An organohydrogenpolysiloxane having at least two Si-H bonds per molecule;

[0030] (D) at least one of a tetraalkoxysilane or a prepolymer of the tetraalkoxysilane; and

[0031] (E) a hydrosilylation reaction catalyst,

[0032] wherein the mass ratio of component (B) to component (A) is in the range of 0.5 to 3.5, and based on the total mass of components (A) to (C), the amount of component (D) is in the range of 0.1% by mass to 9.0% by mass.

[0033] In an embodiment according to the present disclosure, the composition for forming a silicone-based pressure-sensitive adhesive layer further comprises (A') a linear organopolysiloxane that does not contain any carbon-carbon double bond-reactive groups in the molecule. In a preferred embodiment of the present invention, at least a part of the components (A) and (A') is a raw rubber-like organopolysiloxane having a viscosity of 100,000 mPa·s or higher at 25°C or a plasticity value in the range of 50 to 200 as measured by the method described in JIS K6249.

[0034] Furthermore, by using these compositions for forming a silicone-based pressure-sensitive adhesive layer or their cured products as a pressure-sensitive adhesive layer, using them as members of an electronic material or a display device, and an electronic part or a display device provided with them, the problems described above can be solved.

[0035] Effects of the present invention

[0036] According to the present invention, it is possible to overcome to some extent the trade-off between the relatively high adhesion in the silicone-based pressure-sensitive adhesive layer and the relatively low Tg or modulus at a relatively low temperature. That is, the composition for forming a silicone-based pressure-sensitive adhesive layer according to the present invention can form a pressure-sensitive adhesive layer which has excellent curability due to a hydrosilylation reaction, has improved adhesion and a low Tg / modulus at a low temperature, and has soft properties such as a low modulus with small deformation, a low strain with large deformation, and a larger creep compliance. Further, the composition for forming a silicone-based pressure-sensitive adhesive layer or a cured product thereof can be suitably used as a member of a pressure-sensitive adhesive layer, an electronic material, or a display device, and the electrical / electronic part or the display device provided with them satisfies the above-described required characteristics. Therefore, the pressure-sensitive adhesive layer can be applied to a substrate such as an electronic component in a temperature range including a low temperature to room temperature, and thus it is advantageously promoted for industrialization, and it is desired to improve the performance of a laminate such as the resulting display device. Specifically, the present invention can provide a relatively low Tg or modulus and relatively high adhesion in the silicone-based pressure-sensitive adhesive layer without affecting the rheological / viscoelastic properties of the silicone-based pressure-sensitive adhesive layer. This will contribute to expanding the applications and potential markets of silicone-based pressure-sensitive adhesive layers including optically clear adhesives (OCA) applied to various display devices and electronic products. Detailed Description

[0037] [Composition for forming silicone-based PSA]

[0038] First, a composition for forming a silicone-based pressure-sensitive adhesive (PSA) layer according to the present invention will be described. The composition is rapidly cured by a curing reaction including a hydrosilylation reaction to form a pressure-sensitive adhesive layer which has improved adhesion and relatively low shear storage elastic modulus G' and Tg properties at -20°C. Hereinafter, each component in the composition, the range of the organopolysiloxane resin, the mass ratio of the organopolysiloxane resin to the linear organopolysiloxane, and the characteristics of the pressure-sensitive adhesive layer will be described.

[0039] As described above, the composition according to the present invention is characterized by containing at least one of tetraalkoxysilane or a prepolymer of the tetraalkoxysilane as an anchoring additive to improve adhesion without affecting the rheological / viscoelastic properties of the silicone-based pressure-sensitive adhesive layer. Therefore, the present invention can provide a silicone-based pressure-sensitive adhesive layer which has improved adhesion and a relatively low Tg / modulus and soft properties at a relatively low temperature.

[0040] In an embodiment according to the present invention, the composition for forming a silicone-based PSA contains components (A) to (E):

[0041] (A) A linear organopolysiloxane having an average of more than 1 alkenyl group per molecule;

[0042] (B) An organopolysiloxane resin in which the total content of hydroxyl groups and hydrolyzable groups is 2.0% by mass or less relative to all silicon atoms in the molecule;

[0043] (C) An organohydrogenpolysiloxane having at least two Si-H bonds in the molecule;

[0044] (D) At least one of a tetraalkoxysilane or a prepolymer of the tetraalkoxysilane; and

[0045] (E) A hydrosilylation reaction catalyst;

[0046] wherein the mass ratio of component (B) to component (A) is in the range of 0.5 to 3.5; and

[0047] Based on the combined weight of components (A) to (C), the amount of component (D) is in the range of 0.1% by mass to 9.0% by mass, 0.1% by mass to 7.0% by mass, 0.1% by mass to 5.0% by mass, 0.1% by mass to 3.0% by mass, 0.1% by mass to 1.0% by mass, 1.0% by mass to 9.0% by mass, 1.0% by mass to 7.0% by mass, 1.0% by mass to 5.0% by mass, 1.0% by mass to 3.0% by mass, 3.0% by mass to 9.0% by mass, 3.0% by mass to 7.0% by mass, 3.0% by mass to 5.0% by mass, 5.0% by mass to 9.0% by mass, 5.0% by mass to 7.0% by mass, 7.0% by mass to 9.0% by mass.

[0048] In a further embodiment according to the present invention, the composition for forming a silicone-based PSA may further comprise (A') a linear organopolysiloxane that does not contain a carbon-carbon double bond-reactive group in the molecule.

[0049] In addition, since the composition contains a hydrosilylation reaction catalyst, from the perspective of operability, the composition may further contain (F) a curing retarder, and may further contain other additives in an amount that does not conflict with the object of the present invention.

[0050] In the present invention, component (A) is a linear (i.e., in a chain form) organopolysiloxane having on average more than 1 alkenyl group per molecule, wherein the preferred number of alkenyl groups per molecule is not less than 1.5, and wherein the more preferred number of alkenyl groups per molecule is not less than 2.0. In some embodiments according to the present invention, the number of alkenyl groups per molecule on average may range from 1.01 to 5.0, 1.01 to 4.0, 1.01 to 3.0, 1.01 to 2.0, 1.01 to 1.5, 1.5 to 5.0, 1.5 to 4.0, 1.5 to 3.0, 1.5 to 2.0, 2.0 to 5.0, 2.0 to 4.0, 2.0 to 3.0, 3.0 to 5.0, 3.0 to 4.0, or 4.0 to 5.0. Examples of these alkenyl groups of component (A) include alkenyl groups having 2 to 10 carbon atoms, such as vinyl group, allyl group, butenyl group, pentenyl group, hexenyl group, and heptenyl group, wherein specifically preferably vinyl group or hexenyl group. Examples of the bonding positions of these alkenyl groups of component (A) include the molecular chain ends and / or molecular side chains. Note that component (A) may contain a single component or may be a mixture of two or more different components.

[0051] Examples of the silicon-bonded organic groups in component (A) other than the alkenyl groups of the organopolysiloxane include: alkyl groups, such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, and heptyl group; aryl groups, such as phenyl group, tolyl group, xylyl group, and naphthyl group; aralkyl groups, such as benzyl group and phenethyl group; and haloalkyl groups, such as chloromethyl group, 3-chloropropyl group, and 3,3,3-trifluoropropyl group, wherein methyl group and phenyl group are specifically preferred.

[0052] In the present invention, component (A) is different from component (B) and has a linear organopolysiloxane molecular structure. For example, component (A) is preferably linear or partially branched linear and may partially include a cyclic three-dimensional network. Preferably, the main chain of the organopolysiloxane is composed of repeating diorganosiloxane units (i.e., -SiO 2 / 2 or D units), and is preferably a linear or branched diorganopolysiloxane terminated with triorganosilyloxy groups at both molecular ends. Note that the siloxane units providing the branched organopolysiloxane are the T units or Q units described below.

[0053] The properties of component (A) at room temperature can be those of an oily or raw rubber-like substance. The viscosity of component (A) at 25 °C is not less than 50 mPa·s, and specifically preferably not less than 100 mPa·s. Specifically, when the linear organopolysiloxane composition according to the present invention is a solvent type, at least a part of component (A) is (A1) a raw rubber-like alkenyl group-containing organopolysiloxane having a viscosity of not less than 100,000 mPa·s at 25 °C or a plasticity value (read the thickness up to 1 / 100 mm when applying a 1 kgf load to a 4.2 g spherical sample for 3 minutes at 25 °C and multiply this value by 100) measured by the method described in JIS K6249 in the range of 50 to 200, preferably 80 - 200, more preferably 100 - 200.

[0054] Note that in order to prevent contact failures, etc., it is preferable to reduce or eliminate volatile or low molecular weight siloxane oligomers (such as octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), etc.) in the alkenyl groups of the organopolysiloxane. The degree can be designed as needed, but it must be less than 1% by mass of the total component (A), less than 0.1% by mass of each siloxane oligomer, and must be reduced to near the detection limit as needed.

[0055] Although the content of alkenyl groups in component (A1) is not particularly limited, the content of vinyl (CH2=CH) moieties in these alkenyl groups in component (A1) (hereinafter referred to as "vinyl content") can be in the range of 0.005% by mass to 0.400% by mass, preferably in the range of 0.005% by mass to 0.300% by mass, and specifically preferably in the range of 0.005% by mass to 0.200% by mass.

[0056] In some embodiments according to the present invention, component (A) having a viscosity lower than that of component (A1) can also be used as component (A) of the present invention. Specifically, an alkenyl group-containing organopolysiloxane (A2) having a viscosity of less than 100,000 mPa·s at 25 °C can be obtained. Here, the examples other than the viscosity of component (A2) are the same as those of component (A1).

[0057] In the present invention, 50 mass% or more of component (A) is preferably an alkenyl group-containing organopolysiloxane having a high degree of polymerization, which is component (A1), and specifically preferably 75 mass% to 100 mass% thereof is component (A1). That is, when component (A1) (= alkenyl group-containing organopolysiloxane having a relatively high degree of polymerization) and component (A2) (= alkenyl group-containing organopolysiloxane having a relatively low degree of polymerization) are used in combination as component (A) of the present invention, the range of the mass ratio of component (A1) to component (A2) is from 50:50 to 100:0, preferably from 75:25 to 100:0, more preferably from 75:25 to 90:10.

[0058] In the present invention, the organopolysiloxane resin of component (B) is an adhesion-imparting component that imparts adhesion to the substrate, and an organopolysiloxane resin mixture having a constant ratio with component (A) is used to achieve a storage elastic modulus at low temperature and a practical adhesion range. More specifically, component (B) is an organopolysiloxane resin having a small average molecular weight, in which the content of hydroxyl groups or hydrolyzable groups is suppressed, and in which the hydrolysis / polymerization reaction between component (B) tends not to occur, and the selective use of an organopolysiloxane resin having a small average molecular weight achieves a predetermined storage elastic modulus and practical adhesion range in the pressure-sensitive adhesive layer as its cured product.

[0059] Specifically, component (B) is an organopolysiloxane resin in which the total content of hydroxyl groups and hydrolyzable groups is 2.0 mass% or less, 1.6 mass% or less, 1.5 mass% or less, 1.2 mass% or less with respect to the number of all silicon atoms in the molecule. Note that in component (B), the content of such hydroxyl groups and hydrolyzable groups can be expressed by converting all these functional groups into hydroxyl groups. In this case, when calculating the mass% assuming that all these hydrolyzable groups other than these 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 be expressed such that the content of these hydrolyzable groups converted into hydroxyl groups and the hydroxyl groups in the organopolysiloxane resin molecule is 2.0 mass% or less, 1.6 mass% or less, 1.5 mass% or less, 1.2 mass% or less. These hydroxyl groups or hydrolyzable groups are directly bonded to the silicon atoms in the T units or Q units, etc. of these siloxane units in the resin structure described below, and are groups obtained by hydrolyzing these silanes or silane derivatives. Therefore, the content of hydroxyl groups or hydrolyzable groups can be reduced in an organopolysiloxane resin synthesized by hydrolysis with a silylating agent such as trimethylsilane.

[0060] In component (B), when the amount of the hydroxyl group or the hydrolyzable group exceeds the above upper limit, the condensation reaction between these organopolysiloxane resin molecules proceeds, thereby promoting the formation of an organopolysiloxane resin structure having a large molecular weight in the cured product. Such organopolysiloxane resins having a high molecular weight tend to impair the curability of the entire composition, the curability of the composition at low temperatures may be insufficient, and the resulting pressure-sensitive adhesive layer may not have a storage elastic modulus sufficient for practical use.

[0061] In the present invention, component (B) is an organopolysiloxane resin having a three-dimensional structure. Examples thereof include resins composed of R2SiO 2 / 2 units (D units) and RSiO 3 / 2 units (T units) (wherein each R independently represents a monovalent organic group) and having a content of hydroxyl groups or hydrolyzable groups within the above range, resins composed only of T units and having a content of hydroxyl groups or hydrolyzable groups within the above range, and resins composed of R3SiO 1 / 2 units (M units) and SiO 4 / 2 units (Q units) and having a content of hydroxyl groups or hydrolyzable groups within the above range. Specifically, resins composed of R3SiO 1 / 2 units (M units) and SiO 4 / 2 units (Q units) (also referred to as MQ resins) are preferably used, and when all these functional groups are converted to hydroxyl groups, the sum of the contents of the hydroxyl groups and the hydrolyzable groups is preferably in the range of 0.0% by mass to 1.6% by mass.

[0062] The monovalent organic group of R is preferably a monovalent hydrocarbon group having 1 to 10 carbon atoms, examples of which 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 phenethyl group, and a phenylpropyl group. Specifically, 90 mol% or more of R is preferably an alkyl group or a phenyl group having 1 to 6 carbon atoms, and 95 mol% to 100 mol% of R is specifically preferably a methyl group or a phenyl group.

[0063] Preferably, component (B) is (B1) an organopolysiloxane resin composed essentially of R3SiO 1 / 2 units and SiO 4 / 2 units or a mixture thereof, where R is a monovalent organic group and 90 mol% or more of R is an alkyl group or a phenyl group having 1 to 6 carbon atoms. When component (B) is composed of R3SiO 1 / 2 units (M units) and SiO 4 / 2When the resin is composed of units (Q units), the molar ratio of M units to Q units is preferably from 0.5 to 2.0. This is because when the molar ratio is less than 0.5, the adhesion to the substrate may decrease, and when the molar ratio is greater than 2.0, the cohesive strength of the material constituting the adhesive layer decreases. In addition, D units and T units may also be included in component (B) to an extent that does not impair the characteristics of the present invention. Further, in order to prevent contact failures and the like, low molecular weight siloxane oligomers in these organopolysiloxane resins may be reduced or eliminated.

[0064] In the present invention, the weight average molecular weight (Mw) of the organopolysiloxane resin used as component (B) is not limited, and at least one organopolysiloxane resin having a specific Mw or a mixture of two or more organopolysiloxane resins having different Mws can be used as component (B). From a practical point of view, the range of Mw of component (B) measured by gel permeation chromatography (GPC) based on standard polystyrene is from 500 to 20,000 (g / mol), preferably from 1,000 to 17,500 (g / mol), and most preferably from 2,000 to 16,500 (g / mol).

[0065] [Mass ratio of component (B) to component (A)]

[0066] The organopolysiloxane composition for forming a pressure-sensitive adhesive layer according to the present invention characteristically has a mass ratio of component (B) (which is an organopolysiloxane resin) to component (A) (which is a chain-reactive siloxane component) within a specific range. In combination with component (D) as an anchoring additive, the mass ratio of component (B) to component (A) is in the range of 0.5 to 3.5, 0.5 to 2.5, 0.5 to 1.5, 0.5 to 0.75, 0.75 to 3.5, 0.75 to 3.0, 0.75 to 2.5, 0.75 to 1.5, 1.5 to 3.5, 1.5 to 2.5, or 2.5 to 3.5. Specifically, if (A') which is a linear organopolysiloxane not containing a reactive group having a carbon-carbon double bond in the molecule is optional, the mass ratio of component (B) to component (A) is in the range of 0.9 to 1.8, 0.9 to 1.6, 0.9 to 1.4, 0.9 to 1.2, 1.2 to 1.8, 1.2 to 1.6, 1.2 to 1.4, 1.4 to 1.8, 1.4 to 1.6, or 1.6 to 1.8. In contrast, if the composition contains component (A'), and the mass ratio of component (A) to component (A') is in the range of 95:5 to 60:40, 90:10 to 60:40, 80:20 to 60:40, 70:30 to 60:40, 90:10 to 70:30, or 80:20 to 70:30, the mass ratio of component (B) to component (A) is in the range of 0.9 to 2.4, 0.9 to 2.0, 0.9 to 1.6, or 0.9 to 1.2. In other words, if component (A) and (A') are used in the above mass ratio, even if the mass ratio of component (B) to component (A) is in the range greater than 1.8 to 2.4, the technical effects of the present invention can be achieved.

[0067] If component (A') is not an essential component in the composition according to the present invention, in order to achieve the desired adhesiveness and storage elastic modulus, the mass ratio of component (B) to the sum of component (A) and (A') is in the range of 0.9 to 1.8, and can be in the range of 1.0 to 1.77, 1.2 to 1.6, or 1.4 to 1.5. Note that in the case of the mass ratio of component (B) to component (A), the further use of component (A') is one of the preferred embodiments of the present invention without impairing the technical effects of the present invention.

[0068] In contrast, if component (A') is an essential component in the composition according to the present invention and the mass ratio of component (A) to component (A') is in the range of 95:5 to 60:40, the mass ratio of component (B) to the sum of component (A) and (A') is in the range of 0.9 to 2.4, 0.9 to 2.0, 0.9 to 1.6, or 0.9 to 1.2, and can be in the range of 0.9 to 2.3 or in the range of 1.0 to 2.3.

[0069] In the present invention, component (C) is an organohydrogenpolysiloxane having two or more Si-H bonds per molecule and is a crosslinking agent in the organopolysiloxane composition of the present invention. The molecular structure of component (C) is not particularly limited, examples thereof including linear, partially branched linear, branched, cyclic or organopolysiloxane resin structures, with linear, partially branched linear or organopolysiloxane resin structures being preferred. The bonding position of the silicon-bonded hydrogen atoms is not particularly limited, examples thereof including the molecular ends, side chains or both the molecular ends and side chains. The content of the silicon-bonded hydrogen atoms is from 0.1% by mass to 2.0% by mass, preferably from 0.5% by mass to 1.7% by mass.

[0070] Exemplary silicon-bonded organic groups in component (C) include: alkyl groups having 1 to 8 carbon atoms, such as methyl, ethyl, propyl, butyl and octyl groups; aryl groups, such as phenyl and tolyl groups; aralkyl groups, such as benzyl and phenethyl groups; and haloalkyl groups, such as 3-chloropropyl and 3,3,3-trifluoropropyl groups, with 50% mole or more of the total thereof preferably being an alkyl group having 1 to 8 carbon atoms or a phenyl group. From the viewpoint of ease of manufacture and compatibility with the preferred components (A) and (B) described above, other organic groups are preferably methyl or phenyl groups.

[0071] When component (C) of the present invention is an organohydrogenpolysiloxane as an organopolysiloxane resin, examples thereof include organopolysiloxane copolymers composed of siloxane units represented by the general formula: R'3SiO 1 / 2 siloxane units represented by the general formula R'2HSiO 1 / 2 and siloxane units represented by the formula: SiO 4 / 2 organopolysiloxane copolymers composed of siloxane units represented by the general formula: R'2HSiO 1 / 2 and siloxane units represented by the formula: SiO 4 / 2 organopolysiloxane copolymers composed of siloxane units represented by the general formula: R'2HSiO 1 / 2 and siloxane units represented by the formula: R'SiO 3 / 2 organopolysiloxane copolymers composed of siloxane units represented by the general formula: R'HSiO 2 / 2 siloxane units represented by the general formula: R'SiO 3 / 2 or siloxane units represented by the formula: HSiO 3 / 2 and mixtures of two or more types of these organopolysiloxanes. Note that R' in these formulas is an alkyl group, aryl group, aralkyl group or haloalkyl group having 1 to 8 carbon atoms, examples thereof being the same as those described above.

[0072] Specific examples of component (C) include tris(dimethylhydroxysilyloxy)methylsilane, tetrakis(dimethylhydroxysilyloxy)silane, methylhydrogenpolysiloxane capped with trimethylsilyloxy groups at both ends, dimethylsiloxane / methylhydrogensiloxane copolymer capped with trimethylsilyloxy groups at both ends, dimethylsiloxane / methylhydrogensiloxane copolymer capped with dimethylhydroxysilyloxy groups at both ends, cyclic methylhydrogen oligosiloxane, cyclic methylhydrogensiloxane / dimethylsiloxane copolymer, methylhydrogensiloxane / diphenylsiloxane copolymer capped with trimethylsilyloxy groups at both ends, methylhydrogensiloxane / diphenylsiloxane / dimethylsiloxane copolymer capped with trimethylsilyloxy groups at both ends, hydrolysis condensate of trimethylsilane, copolymer composed of (CH3)2HSiO 1 / 2 units and SiO 4 / 2 units, copolymer composed of (CH3)2HSiO 1 / 2 units, SiO 4 / 2 units and (C6H5)SiO 3 / 2 units, copolymer composed of (CH3)2HSiO 1 / 2 units and CH3SiO 3 / 2 units, and mixtures of two or more types thereof.

[0073] Specifically, in the case of a linear structure, methylhydrogenpolysiloxane represented by the molecular structural formula: RTMe2SiO(Me2SiO) q (HMeSiO) r SiMe2RT (where Me is a methyl group, RT is a methyl group or a hydrogen atom, and q and r are numbers satisfying 0.3 ≤ r / (q + r) ≤ 1 and 5 ≤ (q + r) ≤ 200) is preferred. Note that two or more different types of component (C) can be used in combination.

[0074] Similarly, the following organosiloxanes can be given as examples. Note that in these formulas, Me and Ph represent a methyl group and a phenyl group, respectively, m is an integer from 1 to 100, n is an integer from 1 to 50, and b, c, d, and e are each positive numbers, and the sum of b, c, d, and e in one molecule is 1.

[0075] HMe2SiO(Ph2SiO) m SiMe2H

[0076] HMePhSiO(Ph2SiO) m SiMePhH

[0077] HMePhSiO(Ph2SiO) m (MePhSiO)n SiMePhH

[0078] HMePhSiO(Ph2SiO) m (Me2SiO) n SiMePhH

[0079] (HMe2SiO 1 / 2 ) b (PhSiO 3 / 2 ) c

[0080] (HMePhSiO 1 / 2 ) b (PhSiO 3 / 2 ) c

[0081] (HMePhSiO 1 / 2 ) b (HMe2SiO 1 / 2 ) c (PhSiO 3 / 2 ) d

[0082] (HMe2SiO 1 / 2 ) b (Ph2SiO2 / 2) c (PhSiO 3 / 2 ) d

[0083] (HMePhSiO 1 / 2 ) b (Ph2SiO2 / 2) c (PhSiO 3 / 2 ) d

[0084] (HMePhSiO 1 / 2 ) b (HMe2SiO 1 / 2 ) c (Ph2SiO2 / 2) d (PhSiO 3 / 2 ) e 。

[0085] [SiH / Vi ratio]

[0086] The composition according to the present invention is curable by hydrosilylation reaction, and the amount of component (C) is not particularly limited as long as the composition can be sufficiently cured by hydrosilylation reaction. However, the amount of hydrogen atoms bonded to silicon atoms (SiH) in component (C), that is, the molar ratio, is preferably in the range of 7 to 300, 7 to 200, 7 to 100, and can be in the range of 7 to 60, in the range of 7 to 50, or in the range of 7 to 40, relative to the sum of the amounts (number of moles) of alkenyl groups in component (A) and the amount (number of moles) of alkenyl groups in component (B) in the composition.

[0087] In contrast, in order to improve the adhesion to substrates such as glass, the number of SiH groups per molecule can be designed to be 10 or more and 20 or more, preferably more than 20, and more preferably 22 or more. For example, relative to the sum of the amounts (number of moles) of alkenyl groups in component (A) and the amount (number of moles) of alkenyl groups in component (B) in the composition, the amount of hydrogen atoms bonded to silicon atoms (SiH) in component (C) can be designed to be in the range of 10 to 60 and in the range of 10 to 50. When the amount of these SiH groups is below the above lower limit, the technical effect of improving the adhesion to the substrate may not be achieved. In contrast, when the amount of these SiH groups exceeds the above upper limit, the amount of unreacted residual curing agent becomes large, which may have an adverse effect on the cured physical properties such as the brittleness of the cured product, or may cause problems such as gas generation. However, even when the SiH / Vi ratio of the composition is outside the above range, a pressure-sensitive adhesive layer sufficient for practical use can be formed.

[0088] [Hydrosilylation reaction catalyst]

[0089] The organopolysiloxane composition of 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, among which platinum-based catalysts are preferred because they significantly promote the curing of the composition of the present invention. Examples of the platinum-based catalyst include platinum fine powder, chloroplatinic acid, an alcoholic solution of chloroplatinic acid, a platinum-vinylsiloxane complex, a platinum-olefin complex, and a platinum-carbonyl complex, among which the platinum-vinylsiloxane complex is specifically preferred. Examples of the vinylsiloxane include 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, and vinylsiloxanes in which some of the methyl groups of these vinylsiloxanes are replaced by groups selected from the group consisting of nitrile, amide, dioxolane, sulfolane, ethyl group, phenyl group, etc., and vinylsiloxanes in which the vinyl groups of these vinylsiloxanes are replaced by allyl group, hexenyl group, etc. Specifically, 1,3-divinyl-1,1,3,3-tetramethyldisiloxane is preferred because the platinum-vinylsiloxane complex has good stability. As the catalyst for promoting the hydrosilylation reaction, non-platinum-based metal catalysts such as iron, ruthenium, iron / cobalt, etc. can be used.

[0090] Although the content of the hydrosilylation reaction catalyst in the present invention is not specifically limited herein, the amount of platinum-based metal is in the range of 0.1 ppm to 200 ppm, and can be in the range of 0.1 ppm to 150 ppm, in the range of 0.1 ppm to 100 ppm, or in the range of 0.1 ppm to 50 ppm, relative to the total amount of solids in the composition (i.e., without solvent). Here, the platinum-based metal is a Group VIII metal element composed of platinum, rhodium, palladium, ruthenium, and iridium; however, in actual use, the content of platinum metal other than the ligand of the hydrosilylation catalyst is preferably in the range described above. Note that the solid content is the components (mainly the main agent, adhesion-imparting component, crosslinking agent, catalyst, and other non-volatile components) that form a cured layer when the organopolysiloxane composition of the present invention undergoes a curing reaction, and does not include volatile components such as solvents that volatilize during thermal curing.

[0091] When the content of the platinum-based metal in the organopolysiloxane composition according to the present invention is 60 ppm or less, 50 ppm or less, 35 ppm or less, 30 ppm or less, 25 ppm or less or 20 ppm or less, this can suppress discoloration or coloring of the transparent pressure-sensitive adhesive layer, specifically after curing or when heated or exposed to high-energy rays such as UV. At the same time, from the perspective of the curability of the organopolysiloxane composition, the content of the platinum-based metal is not less than 0.1 ppm, because when the content is lower than the lower limit, this may cause curing defects.

[0092] [Component (D) as an anchoring additive]

[0093] Component (D) is at least one tetraalkoxysilane or a prepolymer of the tetraalkoxysilane, which is an anchoring additive of the silicone-based PSA composition of the present invention to improve adhesion without affecting its rheological / viscoelastic properties to the silicone-based pressure-sensitive adhesive layer. Although the rheological / viscoelastic properties in the cured silicone PSA layer are generally determined by its crosslinked polymer structure (including polymer chain length), resin structure (including silicone-resin units and Mw) and the molar ratio therein, resulting in a trade-off relationship between lower Tg or modulus and higher adhesion, in the present invention, by using a tetraalkoxysilane or a prepolymer of the tetraalkoxysilane as an anchoring additive, only the adhesion can be increased without affecting the lower Tg or modulus properties in the cured silicone PSA layer.

[0094] In a preferred embodiment of the present invention, the adhesive force of a pressure-sensitive adhesive layer with a thickness of 50 μm obtained by curing the composition, measured by the 180° peel test method according to JIS Z 0237 at a tensile speed of 300 mm / min on a glass substrate, is more than 20% greater, preferably 30% to 80% greater, than the adhesive force of a pressure-sensitive adhesive layer obtained by the same composition but without component (D). In addition, as measured by the same method, the adhesive force of the pressure-sensitive adhesive layer can be in the range of 800 gf / inch to 3000 gf / inch, preferably in the range of 800 gf / inch to 2000 gf / inch, more preferably in the range of 800 gf / inch to 1500 gf / inch, with lower Tg or modulus.

[0095] In order to achieve greater adhesion, component (D) is required to be at least one tetraalkoxysilane or a prepolymer of the tetraalkoxysilane, examples of which are tetramethoxysilane, tetraethoxysilane or a mixture thereof. As the prepolymer of the tetraalkoxysilane, a complete or partial condensation reaction product of the tetraalkoxysilane is exemplified. Using other silanes such as glycidoxypropyltrimethoxysilane or vinyltrimethoxysilane instead of the tetraalkoxysilane will not improve or enhance the adhesion without affecting its rheological / viscoelastic properties for the silicone-based pressure-sensitive adhesive layer. In addition, in order to achieve a sufficient improvement in the adhesion, it is assumed that the mass ratio of component (B) to component (A) is in the range of 0.5 to 3.5, and based on the total mass of components (A) to (C), the amount of component (D) is in the range of 0.1% by mass to 9.0% by mass, preferably in the range of 0.2% by mass to 7.0% by mass, more preferably in the range of 0.5% by mass to 5.0% by mass. When the amount of component (D) is lower than the above lower limit, the technical effect of improving the adhesion to the substrate may not be fully achieved. In contrast, when the amount of component (D) exceeds the above upper limit, the excessive component (D) may have an adverse effect on the cured physical properties.

[0096] In the present invention, component (F) is a curing retarder (= curing inhibitor), and is compounded to inhibit the crosslinking reaction between the alkenyl groups in the composition and these SiH groups in component (C) to extend the service life at room temperature and improve the storage stability. Therefore, in actual use, component (F) can be added to the organopolysiloxane composition for forming a pressure-sensitive adhesive layer according to the present invention.

[0097] Specific examples of component (F) include acetylenic compounds, enyne compounds, organic nitrogen compounds, organic phosphorus compounds and oxime compounds. Specific examples include: acetylenic 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, phenylbutanol, etc.; enyne compounds such as 3-methyl-3-penten-1-yne, 3,5-dimethyl-3-hexen-1-yne, etc.; methylvinylcyclosiloxanes such as 2-ethynyl-4-methyl-2-pentene, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane, etc., and benzotriazoles.

[0098] From the perspective of the curing behavior of the composition, the organopolysiloxane composition for forming a pressure-sensitive adhesive layer of the present invention is preferably curable at 80°C to 200°C and has a viscosity increase within 1.5 times after 8 hours at room temperature after the preparation of the composition. From the perspectives of workability, pot life, and properties after curing, it is important to suppress thickening, and a large amount of an excess of component (C) is contained, where even if the content of the platinum-based metal is optionally low, curability can be ensured by curing at a high temperature of at least a specific temperature (80°C to 200°C). Note that such a composition can be achieved by selecting a suitable combination and blending amount of the respective components, the hydrosilylation catalyst, and component (F) described above.

[0099] In addition to the preferred components (A) and (B) described above, the organopolysiloxane composition of the present invention may further contain an organic solvent as a solvent. The type and blending amount of the organic solvent can be adjusted in consideration of coating workability and the like. Exemplary organic solvents include: aromatic hydrocarbon-based solvents such as toluene, xylene, and benzene; aliphatic hydrocarbon-based solvents such as heptane, hexane, octane, and isoparaffin; ester-based solvents such as ethyl acetate and isobutyl acetate; ether-based solvents such as diisopropyl ether and 1,4-dioxane; chlorinated aliphatic hydrocarbon-based solvents such as trichloroethylene, perchloroethylene, and dichloromethane; and solvent volatile oils; among which two or more types can be combined according to the wettability of the sheet substrate and the like. The blending amount of the organic solvent is preferably an amount such that the mixture of components (A) to (C) can be uniformly applied to the surface of the sheet substrate. For example, the blending amount can be 5 to 3000 parts by mass per 100 parts by mass of the total amount of components (A), (B), and (C).

[0100] The organopolysiloxane composition of the present invention may optionally contain components other than the components described above to such an extent that the technical effects of the present invention are not impaired. For example, the composition may contain: an adhesion promoter; non-reactive organopolysiloxanes such as polydimethylsiloxane or polydimethyldiphenylsiloxane; antioxidants such as phenolic, quinone-type, amine-type, phosphorus-type, phosphite-type, sulfur-type, or thioether-type antioxidants; flame retardants such as phosphate-type, halogen-type, phosphorus-type, and antimony-type flame retardants; and one or more types of antistatic agents composed of cationic surfactants, anionic surfactants, nonionic surfactants, etc. Note that in addition to these components, pigments, dyes, inorganic fine particles (e.g., reinforcing fillers, dielectric fillers, conductive fillers, heat conductive fillers), etc. may also be optionally blended.

[0101] [(A') Linear organopolysiloxane having no reactive group containing a carbon-carbon double bond in the molecule]

[0102] The organopolysiloxane composition according to the present invention may comprise a non-reactive organopolysiloxane that does not contain a reactive group having a carbon-carbon double bond, such as an alkenyl group, an acryloyl group, or a methacryloyl group, such as polydimethylsiloxane or polydimethyldiphenylsiloxane. As a result, the loss coefficient (tan δ), storage elastic modulus (G'), loss modulus (G"), and adhesiveness of the pressure-sensitive adhesive layer can be improved. For example, polydimethylsiloxane having a hydroxyl group at the terminal or polydimethylsiloxane or polydimethyldiphenylsiloxane having a trimethylsilyloxy group at the terminal can be used to increase the loss coefficient of the pressure-sensitive adhesive layer, and such compositions are included within the scope of the present invention.

[0103] Preferably, component (A') is (A'1) a raw rubber-like organopolysiloxane having a viscosity of 100,000 mPa·s or higher at 25 °C or a plasticity value in the range of 50 to 200 as measured by the method described in JIS K6249.

[0104] In the most preferred embodiment of the present invention, assuming that component (D) is used as a fixing additive to improve the adhesiveness in the cured PSA layer, both component (A) and component (A') are 50% to 100% by mass of a raw rubber-like organopolysiloxane having a higher viscosity or plasticity value. Specifically, in a preferred embodiment of the present invention, 50% to 100% by mass of the component (A) is (A1) a raw rubber-like alkenyl group-containing organopolysiloxane having a viscosity of 100,000 mPa·s or higher at 25 °C or a plasticity value in the range of 50 to 200 as measured by the method described in JIS K6249, and the content of the vinyl (CH2=CH-) moiety of the alkenyl group is in the range of 0.005% to 0.400% by mass; 50% to 100% by mass of the optional component (A') is (A'1) a raw rubber-like organopolysiloxane having a viscosity of 100,000 mPa·s or higher at 25 °C or a plasticity value in the range of 50 to 200 as measured by the method described in JIS K6249; and the range of the mass ratio of component (A) to component (A') in the composition is 100:0 to 40:60.

[0105] The method for preparing the composition for forming a silicone-based PSA is not particularly limited and is carried out by uniformly mixing the corresponding components. A solvent can be added as needed, and the composition can be prepared by mixing at a temperature of 0 °C to 200 °C using a known stirrer or kneader.

[0106] [Forming an adhesive layer using the composition for forming silicone-based PSA]

[0107] The aforementioned composition for forming a silicone-based PSA forms a cured adhesive layer when applied to a substrate and forms a cured product by heating under temperature conditions of 80°C to 200°C, preferably under temperature conditions of 90°C to 190°C. Examples of application methods include gravure coating, offset coating, offset gravure, roll coating, reverse roll coating, air knife coating, curtain coating, and comma coating.

[0108] This cured adhesive layer from the composition for forming a silicone-based PSA is disposed between these functional layers to bond / assemble these layers in the electronic article of the present invention.

[0109] [Storage elastic modulus and other viscoelastic properties]

[0110] The pressure-sensitive adhesive layer (obtained by curing) of the aforementioned composition for forming a silicone-based PSA according to the present invention has a shear storage modulus G' at -20°C in the range of 0.01 MPa to 2.0 MPa. This storage modulus G' can be in the range of 0.02 MPa to 1.5 MPa and in the range of 0.03 MPa to 1.2 MPa, and those in the range of 0.04 MPa to 1.0 MPa are also suitably included within the scope of the present invention. The organopolysiloxane composition for forming a pressure-sensitive adhesive layer according to the present invention, which has a relatively low storage modulus G' at low temperatures and the above-mentioned practical adhesive force, is suitable as a component of an electronic device or an electrical device (such as a speaker or a transducer), and is suitable for applications in advanced electronic materials and display elements such as in the field of smart devices in order to form an elastic adhesive component.

[0111] The storage modulus (G') of the pressure-sensitive adhesive layer according to the present invention can be measured by known measurement methods. For example, it can be measured using a storage modulus (G') MCR301 viscoelastic measurement device (available from Anton Paar). Using a disk-shaped sample with a diameter of approximately 8 mm and a thickness of approximately 0.5 mm to 1 mm, this value can be measured in the range of -40°C to 100°C as the value at -20°C, using this temperature, using 8 mm parallel plates, a frequency of 1 Hz, a strain of 0.1%, and a heating rate of 3°C / minute.

[0112] The storage modulus G' of the pressure-sensitive adhesive layer according to the present invention at -20°C at 1.0 Hz can be not less than three times the storage modulus G' at 25°C at 1.0 Hz.

[0113] [Properties related to the transparency, hue or coloring and discoloration of the pressure-sensitive adhesive layer]

[0114] The aforementioned silicone-based PSA layer of the present invention can be substantially transparent, translucent, or opaque, such that its transparency can be designed according to the application of the interlayer adhesive layer. For example, as the interlayer pressure-sensitive adhesive layer applied to the display device of the present invention, a film-shaped cured product with a thickness of 10 μm to 1000 μm obtained by curing the composition forming the silicone-based PSA is preferably visually transparent and preferably does not contain coloring additives such as carbon black. Note that in the case of being visually transparent, or more objectively, when the value of air is 100%, the light transmittance of this pressure-sensitive adhesive layer for the display device formed by a cured layer with a thickness of 100 μm is 80% or higher at a wavelength of 450 nm, and suitably 90% or higher, and can be designed to be 95% or higher. In contrast, in the adhesion of electrical or electronic components where light transmittance is not required, a translucent to opaque pressure-sensitive adhesive layer can be used, and filler components or additives that impair colorability or light transmittance can be used according to the required properties other than light transmittance.

[0115] The adhesive layer can be designed by optionally reducing the content of the platinum-based metal in the cured layer such that, in addition to the above transparency, the cured product is not colored. Specifically, after curing a cured layer with a thickness of 100 μm obtained by curing the organopolysiloxane composition of the present invention, the b* value measured immediately using the L*a*b* color system specified in JIS Z 8729 can be designed to be not greater than 0.15 and not greater than 0.10. Having such a b* value means that the cured layer is substantially transparent and not yellow.

[0116] Even when the cured layer of the present invention is exposed to high temperature or high-energy beams such as UV rays for a long time, it can be designed such that its hue does not change significantly and specifically the problem of yellowing does not occur. Specifically, even when any of the following evaluations is performed, after evaluating a cured layer with a thickness of 100 μm obtained by curing the organopolysiloxane composition of the present invention, the change in the b* value (Δb*) measured immediately using the L*a*b* color system specified in JIS Z 8729 can be designed to be not greater than 0.20 and preferably not greater than 0.15. Note that Δb* is the absolute value of the numerical change.

[0117] (1) Thermal aging evaluation: Aging the cured layer at 105 °C for 300 hours.

[0118] (2) High-energy beam irradiation: Using a light intensity of 12 mW / cm at 365 nm 2 and a light intensity of 3.5 mW / cm at 254 nm 2A mercury lamp (e.g., optical module X manufactured by Ushio Electric Co., Ltd., etc.) irradiates a sample of the cured layer with UV light at room temperature for 75 hours.

[0119] [Used as a pressure-sensitive adhesive layer]

[0120] The cured product of the present invention can be specifically used as a pressure-sensitive adhesive layer. Additionally, in order to improve the adhesiveness to an adherend, surface treatment such as primer treatment, corona treatment, etching treatment, or plasma treatment can be performed on the surface of the pressure-sensitive adhesive layer or the substrate. However, since the pressure-sensitive adhesive layer according to the present invention has excellent adhesiveness to substrates such as display devices, as described above, these steps can be added if necessary to further improve the adhesion to the adherend, and higher production efficiency can be achieved by eliminating these steps.

[0121] The curable organopolysiloxane composition of the present invention is cured after the following steps: applying the composition onto a release liner, heating under the temperature conditions described above, and then, after peeling off the release liner and attaching the composition to a film-like substrate, a strip-like substrate, or a sheet-like substrate (hereinafter referred to as "film-like substrate"), or applying it onto a film-like substrate, curing by heating under the temperature conditions described above, thereby forming a pressure-sensitive adhesive layer on the surface of the substrate. The laminate provided with a cured layer (specifically, a film-like pressure-sensitive adhesive layer) obtained by curing the organopolysiloxane composition of the present invention on these film-like substrates can be used for adhesive tapes, adhesive bandages, cryogenic supports, transfer films, labels, badges, and decorative or explanatory signs. Further, the cured layer obtained by curing the organopolysiloxane composition of the present invention can be used for assembling automotive parts, toys, electronic circuits, or keyboards. Alternatively, the cured layer formed by curing the organopolysiloxane composition of the present invention, and specifically the film-like pressure-sensitive adhesive layer, can be used for constructing and using laminated touchscreens or flat panel displays.

[0122] Exemplary types of substrates include: cardboard; carton board; clay-coated paper; polyolefin-laminated paper, specifically polyethylene-laminated paper; synthetic resin films and sheets; natural fiber woven materials; synthetic fiber woven materials; artificial leather woven materials; and metal foils. Specifically, synthetic resin films and sheets are preferred, and examples of synthetic resins include polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polycarbonate, polyethylene terephthalate, cycloolefin, and nylon. In cases where heat resistance is required, heat-resistant synthetic resin films such as polyimide, polyether ether ketone, polyethylene naphthalate (PEN), liquid crystal polyacrylate, polyamideimide, polyethersulfone, etc. are specifically preferred. Meanwhile, for applications where visibility is required, such as display devices, transparent substrates and specifically transparent materials such as polypropylene, polystyrene, polyvinylidene chloride, polycarbonate, polyethylene terephthalate, etc. are preferred.

[0123] The substrate is preferably a film-like or sheet-like substrate. Its thickness is not specifically limited and can be designed to a desired thickness according to the application. In addition, in order to improve the adhesion between the support film and the pressure-sensitive adhesive layer, a support film that has been subjected to primer treatment, corona treatment, etching treatment, or plasma treatment can be used. In addition, surface treatment such as anti-scratch, anti-fouling, anti-fingerprint adhesion, anti-glare, anti-reflection, anti-static treatment, or other treatments can be performed on the surface of the film-like substrate that is opposite to the surface of the pressure-sensitive adhesive layer.

[0124] As for the coating method for the substrate, gravure coating, offset coating, offset gravure, roll coating using an offset transfer roll coater, reverse roll coating, air knife coating, curtain coating using a curtain coater, comma coating, Meyer bar, or another known method for the purpose of forming a cured layer can be used without limitation.

[0125] The coating amount can be designed to a desired thickness according to applications such as display devices. As an example, the thickness of the pressure-sensitive adhesive layer after curing can be 1 μm to 1000 μm, 5 μm to 900 μm, or 10 μm to 800 μm; however, it is not limited thereto.

[0126] According to the required characteristics, the pressure-sensitive adhesive layer according to the present invention can be a single layer or a multi-layer structure obtained by laminating two or more pressure-sensitive adhesive layers. The multi-layer pressure-sensitive adhesive layer can be formed by bonding pressure-sensitive adhesive films (which are formed film by film) thereto, or the steps of applying and curing the organopolysiloxane composition for forming the pressure-sensitive adhesive layer can be performed multiple times on a film substrate (including a release layer), etc.

[0127] In addition to the bonding or adhering function between components, the pressure-sensitive adhesive layer according to the present invention can also serve as other functional layers selected from dielectric layers, conductive layers, heat-dissipating layers, insulating layers, reinforcing layers, etc. Additionally, as an interlayer silicone-based PSA layer, in addition to the bonding or adhering function between components, the silicone-based PSA layer of the present invention can be applied as a damping / shock-absorbing layer.

[0128] Preferably, since the interlayer adhesive layer has both an assembly / bonding layer function and a damping / shock-absorbing layer function, an electronic article having the silicone-based PSA layer of the present invention does not require an interlayer damping / shock-absorbing layer to be arranged between the two functional layers. For this dual-functional feature of the interlayer adhesive layer, through the present invention, the electronic article can be constructed without using any other interlayer damping / shock-absorbing layer other than the interlayer adhesive layer according to the present invention between the two functional layers.

[0129] In a preferred embodiment, the electronic article having the silicone-based PSA layer of the present invention as its interlayer adhesive layer is an LED or OLED type display device and their modules, which have a structure in which a transparent display unit is directly bonded or assembled to other functional units with the interlayer adhesive layer, and the interlayer adhesive layer is a single adhesive / assembly layer sandwiched between the units in the display device. Since these display devices having the silicone-based PSA layer can be designed to have substantially no additional interlayer damping / shock-absorbing layer other than the interlayer adhesive layer of the present invention (i.e., thick and multi-layer damping / shock-absorbing layers are omitted from these devices), the total thickness of the display can be thinner and lighter compared to conventional devices.

[0130] When the cured layer obtained by curing the organopolysiloxane composition of the present invention is a pressure-sensitive adhesive layer, specifically in the case of a pressure-sensitive adhesive layer, preferably, the cured layer is treated as a laminated film that is peelably adhered to a film substrate provided with a release coating layer having release coating ability. The release layer can also be referred to as a release liner, separator, release layer, or release coating, and can preferably be a release layer having release coating ability, such as a silicone-based release agent, fluorine-based release agent, alkyd-based release agent, or fluorosilicone-based release agent, or the release layer can be formed as a substrate itself that is not easily adhered to the resin sheet for the pressure-sensitive adhesive layer of the present invention by forming physically fine irregularities on the surface of the substrate. Specifically, in the laminate according to the present invention, a release layer obtained by curing a fluorosilicone release agent is preferably used as the release layer.

[0131] The cured product obtained by curing the organopolysiloxane composition according to the present invention has both the viscoelasticity and adhesive strength as described above, such that it can be used as a component of various types of electronic devices or electrical apparatuses as an elastic adhesive component. Specifically, it is useful as a component for electronic materials, components for display devices, and components for transducers (including sensors, speakers, actuators, and generators), and a suitable application of the cured product is a component for electronic parts or display devices. The cured product according to the present invention can be transparent or opaque. Specifically, a film-like cured product, specifically a substantially transparent pressure-sensitive adhesive film, is suitable as a component for a display panel or a display, and is particularly useful in a so-called touch panel application in which a device, specifically an electronic device, can be operated by touching the screen with a fingertip or the like. In addition, the opaque elastic adhesive layer does not need to have transparency, which makes it particularly applicable to applications of film-like or sheet-like components used in sensors, speakers, actuators, etc., which require the adhesive layer itself to have constant elasticity or flexibility.

[0132] Specifically, the pressure-sensitive adhesive layer obtained by curing the organopolysiloxane composition according to the present invention can achieve pressure-sensitive adhesive properties comparable to those of a conventional silicone pressure-sensitive adhesive layer, and can improve the adhesion to a substrate such as a display device without causing problems such as poor curing or reduced curability.

[0133] [Components of a display panel or monitor]

[0134] The cured product obtained by curing the organopolysiloxane composition of the present invention can be used to construct and use a laminated touch screen or a flat panel display, and the specific method of use thereof can be a known method of using a pressure-sensitive adhesive layer (specifically, silicone PSA) without any specific limitation.

[0135] For example, the cured product obtained by curing the organopolysiloxane composition of the present invention can be used to produce a display device, such as a touch panel, as an optically transparent silicone-based pressure-sensitive adhesive film or adhesive layer disclosed in JP 2014-522436 W or JP 2013-512326W as described above. Specifically, the cured product obtained by curing the organopolysiloxane composition of the present invention can be used as the adhesive layer or adhesive film described in JP 2013-512326W without any specific limitation.

[0136] As an example, the touch panel according to the present invention may be a touch panel including a base material such as a conductive plastic film, the base material having a conductive layer formed on one surface and a cured layer obtained by curing the curable organopolysiloxane composition of the present invention, the cured layer being connected to the surface on the side where the conductive layer is formed or on the opposite side thereof. The base material is preferably a sheet-like or film-like base material, examples of which include a resin film or a glass plate. Further, the conductive plastic film may be a resin film or a glass plate having an ITO layer formed on one surface thereof, specifically a polyethylene terephthalate film. These are disclosed in JP 2013-512326 W etc. described above.

[0137] In addition, the cured product obtained by curing the organopolysiloxane composition of the present invention can be used as an adhesive film for a polarizing plate used in the production of a display device such as a touch panel, or can be used as a pressure-sensitive adhesive layer used in the adhesion between a touch panel and a display module described in Japanese Unexamined Patent Application Publication No. 2013-065009.

[0138] Industrial applicability

[0139] The application of the composition for forming a silicone-based pressure-sensitive adhesive layer according to the present invention and the cured product obtained by curing the composition is not limited to the above disclosure. The pressure-sensitive adhesive film provided with the cured product obtained by curing the composition can be used in various display devices for displaying characters, symbols, and images, such as instrument panel displays of television receivers, computer monitors, personal digital assistant monitors, surveillance monitors, cameras, digital cameras, mobile phones, personal digital assistants, automobiles, etc., instrument panel displays of various equipment, devices, and instruments, ticket vending machines, automated teller machines, in-vehicle display devices, and in-vehicle transmission screens. The surface shape of such display devices can be a curved shape or an arcuate shape instead of a flat surface, and examples thereof include curved displays or curved transmissive screens for automobiles (including electric vehicles), airplanes, etc., and various flat panel displays (FPDs). Further, these display devices can display on the screen or display icons for executing functions or programs, notification indicators such as emails, programs, etc., and operation buttons for various devices such as automotive navigation devices, membranes of speakers, audio devices, and air conditioning devices, and have a touch panel function that enables input operations to be added by touching these icons, notification indicators, or operation buttons with a finger. Applications using CRT displays, liquid crystal displays, plasma displays, organic electroluminescent (EL) displays, inorganic EL displays, LED displays, surface-conduction electron-emitter displays (SED), field emission displays (FED), and other display devices, or touch panels using these display devices are possible. In addition, the cured product obtained by curing the composition has excellent adhesion and viscoelastic properties, and in addition to being able to be used as a sealing layer or adhesive layer used in secondary batteries, fuel cells, or solar cell modules, it also allows it to be used as a film-like or sheet-like member as a member for transducers (including sensors, speakers, actuators, etc.).

[0140] The pressure-sensitive adhesive layer obtained by curing the composition for forming a silicone-based pressure-sensitive adhesive layer according to the present invention can be substantially transparent, and in addition to having excellent adhesion to substrates such as various display devices, it does not cause problems such as poor curing or reduced curability. Therefore, the pressure-sensitive adhesive layer can be applied to a vehicle display device that exhibits good visibility and operability of the displayed content over an extended period of time, and specifically, a vehicle display device having a curved screen or a curved display and optionally equipped with a touch panel function. For example, vehicle display devices equipped with a curved display surface are disclosed in Japanese Unexamined Patent Application Publication No. 2017-047767, Japanese Unexamined Patent Application Publication No. 2014-182335, Japanese Unexamined Patent Application Publication No. 2014-063064, Japanese Unexamined Patent Application Publication No. 2013-233852, etc.; however, the pressure-sensitive adhesive layer of the present invention can be appropriately applied or replaced as part or all of the adhesive layer or pressure-sensitive adhesive layer that requires transparency in these documents. Further, it goes without saying that regarding the organopolysiloxane composition for forming a pressure-sensitive adhesive layer according to the present invention, the currently used adhesive layer or the pressure-sensitive adhesive layer that requires transparency can also be used as a substitute for other known curved display devices, and in order to further exhibit the advantages of the pressure-sensitive adhesive of the present invention, it is preferable to adjust the design of the display device or the thickness of the member using known techniques.

[0141] Note that the transparent film-like substrate provided with the pressure-sensitive adhesive layer of the present invention can be used for purposes such as scratch prevention, stain prevention, fingerprint adhesion prevention, antistatic, antiglare, and privacy protection on the surfaces of these displays.

[0142] Examples

[0143] These examples are intended to illustrate the present invention to those skilled in the art and are not to be construed as limiting the scope of the present invention described in the claims. Note that "curing" in each of the examples, comparative examples, and reference examples means that each composition is completely cured under the corresponding curing conditions.

[0144] The materials in Table 1 are used in these examples. These materials of these curable reactive organopolysiloxane compositions are shown in Table 2. Note that the viscosity and plasticity values of each component are measured at room temperature by the following methods.

[0145] (Viscosity)

[0146] The viscosity (mPa·s) is the value measured using a rotational viscometer in accordance with JIS K7117-1, while the kinematic viscosity (mm² / s) is the value measured using an Ubbelohde viscometer in accordance with JIS Z8803).

[0147] (Plastic value)

[0148] The plasticity value is expressed as the value measured according to the method specified in JIS K 6249 (when a 1 kgf load is applied to a 4.2 g spherical sample at 25°C for 3 minutes, the thickness read to the nearest 1 / 100 mm is multiplied by 100).

[0149] Table 1. Components of the composition for forming silicone-based PSA

[0150]

[0151] [Preparation of the composition for forming silicone-based PSA]

[0152] Each of the examples, comparative examples, and reference examples described herein for forming the silicone-based PSA was prepared using these components shown in Table 1. Additionally, the formulations and adhesions of the working examples, comparative examples, and reference examples are summarized in Table 2.

[0153] (Measurement of the molecular weight of the organopolysiloxane component)

[0154] The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of organopolysiloxane components such as organopolysiloxane resins were determined according to standard polystyrene using gel permeation chromatography (GPC) available from Waters and tetrahydrofuran (THF) as a solvent.

[0155] (Measurement of the content of hydroxyl groups (OH) in the organopolysiloxane resin)

[0156] Using an ACP-300 ²⁹Si NMR spectrometer available from Bruker equipped with a no-glass probe, when the chemical shift of tetramethylsilane is set to 0 ppm, the molar content is obtained from the ratio of the Si(OH)O 2 / 3 units to the presence of all silicon atoms appearing at -93 ppm to -103.5 ppm, and then further converted to the mass % of hydroxyl groups (OH) in the organopolysiloxane resin. Note that in the following examples, the organopolysiloxane resin does not contain hydrolysable groups other than hydroxyl groups.

[0157] (Adhesion measurement)

[0158] Each composition was applied to a PET film (available from Toray Co., Ltd., product name: Lumirror (registered trademark) S10, thickness: 50 μm) such that the thickness after curing was 50 μm, and then cured at 150 °C for 3 minutes. After standing for one day, the sample was cut into 20 mm wide, and the surface of the adhesive layer was attached to a glass slide (provided by Sinopharm Chemical Reagent Co., Ltd, 25.4 x 76.2 x 2.0 mm) or a polymethyl methacrylate (PMMA) plate (manufactured by Paltec, ACRYLITE L001, 50 x 120 x 2 mm) using a roller to form a test piece, and kept at room temperature for 30 minutes. Regarding the test pieces using glass or PMMA plates, the adhesive strength was measured at a tensile speed of 300 mm / min using an RTC-1210 tensile tester manufactured by Orientec Co., Ltd and a 180° peel test method according to JIS Z0237 (measured at a width of 20 mm and converted to the display unit gf / inch).

[0159] Comparative Example 1

[0160] 18.64 parts by weight of the vinyl-functional polydimethylsiloxane of component A,

[0161] 4.66 parts by weight of the methyl-terminated high molecular weight polydimethylsiloxane of component A',

[0162] 40.00 parts by weight of the trimethylsilyl-terminated MQ resin of component B,

[0163] 23.30 parts by weight of toluene of component G,

[0164] 0.4 part by weight of the trimethylsilyl-terminated poly(dimethylsiloxane-co-methylhydrogen) siloxane of component C,

[0165] 0.2 part by weight of 1-ethynyl-1-cyclohexanol of component F

[0166] were thoroughly mixed at room temperature,

[0167] and then 0.36 part by weight of the platinum-based hydrosilylation reaction catalyst of component E was added to the mixture to form a curable reactive organopolysiloxane composition.

[0168] The molar ratio (SiH / Vi ratio) of the amount of SiH groups in component (E) to the alkenyl groups in component (A) was 33.

[0169] The composition was cured by the above method, and then the adhesion to the glass slide was measured by the above method, and the evaluation results and the like are shown in Table 2.

[0170] Comparative Example 2

[0171] 16.31 parts by weight of the vinyl-functional polydimethylsiloxane of component A,

[0172] 6.99 parts by weight of the methyl-capped high molecular weight polydimethylsiloxane of component A',

[0173] 45.00 parts by weight of the trimethylsilyl-capped MQ resin of component B,

[0174] 23.30 parts by weight of toluene of component G,

[0175] 0.4 part by weight of the trimethylsilyl-capped poly(dimethylsiloxane-co-methylhydrogen) siloxane of component C,

[0176] 0.2 part by weight of 1-ethynyl-1-cyclohexanol of component F

[0177] were thoroughly mixed at room temperature,

[0178] and then 0.36 part by weight of the platinum-based hydrosilylation reaction catalyst of component E was added to the mixture to form a curable reactive organopolysiloxane composition.

[0179] The molar ratio (SiH / Vi ratio) of the amount of SiH groups in component (E) to the alkenyl groups in component (A) was 37.

[0180] The composition was cured by the above method, and then the adhesion to the glass slide was measured by the above method, and the evaluation results and the like are shown in Table 2.

[0181] Comparative Example 3

[0182] 13.98 parts by weight of the vinyl-functional polydimethylsiloxane of component A,

[0183] 9.32 parts by weight of the methyl-capped high molecular weight polydimethylsiloxane of component A',

[0184] 45.00 parts by weight of the trimethylsilyl-capped MQ resin of component B,

[0185] 23.30 parts by weight of toluene of component G,

[0186] 0.4 part by weight of the trimethylsilyl-capped poly(dimethylsiloxane-co-methylhydrogen) siloxane of component C,

[0187] 0.2 parts by weight of 1-ethynyl-1-cyclohexanol of component F

[0188] Mix well at room temperature,

[0189] Then add 0.36 parts by weight of the platinum-based hydrosilylation reaction catalyst of component E to the mixture to form a curable reactive organopolysiloxane composition.

[0190] The molar ratio (SiH / Vi ratio) of the amount of SiH groups in component (E) to the amount of alkenyl groups in component (A) is 44.

[0191] The composition is cured by the above method, and then the adhesion to the glass slide is measured by the above method, and the evaluation results are shown in Table 2.

[0192] Comparative Example 4

[0193] 11.65 parts by weight of vinyl-functional polydimethylsiloxane of component A,

[0194] 11.65 parts by weight of methyl-terminated high molecular weight polydimethylsiloxane of component A',

[0195] 45.00 parts by weight of trimethylsilyl-terminated MQ resin of component B,

[0196] 23.30 parts by weight of toluene of component G,

[0197] 0.4 parts by weight of trimethylsilyl-terminated poly(dimethylsiloxane-co-methylhydrogen) siloxane of component C,

[0198] 0.2 parts by weight of 1-ethynyl-1-cyclohexanol of component F

[0199] Mix well at room temperature,

[0200] Then add 0.36 parts by weight of the platinum-based hydrosilylation reaction catalyst of component E to the mixture to form a curable reactive organopolysiloxane composition.

[0201] The molar ratio (SiH / Vi ratio) of the amount of SiH groups in component (E) to the amount of alkenyl groups in component (A) is 52.

[0202] The composition is cured by the above method, and then the adhesion to the glass slide is measured by the above method, and the evaluation results are shown in Table 2.

[0203] Comparative Example 5

[0204] 16.31 parts by weight of vinyl-functional polydimethylsiloxane of component A,

[0205] 6.99 parts by weight of a methyl-terminated high molecular weight polydimethylsiloxane of component A'

[0206] 65.37 parts by weight of a trimethylsilyl-terminated MQ resin of component B

[0207] 23.30 parts by weight of toluene of component G

[0208] 0.053 parts by weight of a trimethylsilyl-terminated poly(dimethylsiloxane-co-methylhydrogen) siloxane of component C

[0209] 0.06 parts by weight of 1-ethynyl-1-cyclohexanol of component F

[0210] Mix well at room temperature.

[0211] Then, 0.25 parts by weight of a platinum-based hydrosilylation reaction catalyst of component E is added to the mixture to form a curable reactive organopolysiloxane composition.

[0212] The molar ratio (SiH / Vi ratio) of the amount of SiH groups in component (E) to the amount of vinyl groups in component (A) is 5.0.

[0213] The composition is cured by the above method, and then the adhesion to a PMMA plate is measured by the above method, and the evaluation results are shown in Table 2.

[0214] Example 1

[0215] 18.64 parts by weight of a vinyl-functional polydimethylsiloxane of component A

[0216] 4.66 parts by weight of a methyl-terminated high molecular weight polydimethylsiloxane of component A'

[0217] 40.00 parts by weight of a trimethylsilyl-terminated MQ resin of component B

[0218] 23.30 parts by weight of toluene of component G

[0219] 0.4 parts by weight of a trimethylsilyl-terminated poly(dimethylsiloxane-co-methylhydrogen) siloxane of component C

[0220] 1.0 parts by weight of tetraethoxysilane of component D

[0221] 0.2 parts by weight of 1-ethynyl-1-cyclohexanol of component F

[0222] Mix well at room temperature.

[0223] Then, 0.36 parts by weight of a platinum-based hydrosilylation reaction catalyst of component (E) was added to the mixture to form a curable reactive organopolysiloxane composition.

[0224] The molar ratio (SiH / Vi ratio) of the amount of SiH groups in component (E) to the amount of vinyl groups in component (A) was 33.

[0225] The composition was cured by the above method, and then the adhesion to a glass slide was measured by the above method, and the evaluation results are shown in Table 2.

[0226] Example 2

[0227] 18.64 parts by weight of vinyl-functional polydimethylsiloxane of component (A),

[0228] 4.66 parts by weight of methyl-terminated high molecular weight polydimethylsiloxane of component (A'),

[0229] 40.00 parts by weight of trimethylsilyl-terminated MQ resin of component (B),

[0230] 23.30 parts by weight of toluene of component (G),

[0231] 0.4 parts by weight of trimethylsilyl-terminated poly(dimethylsiloxane-co-methylhydrogen) siloxane of component (C),

[0232] 2.0 parts by weight of tetraethoxysilane of component (D),

[0233] 0.2 parts by weight of 1-ethynyl-1-cyclohexanol of component (F)

[0234] They were thoroughly mixed at room temperature,

[0235] Then, 0.36 parts by weight of a platinum-based hydrosilylation reaction catalyst of component (E) was added to the mixture to form a curable reactive organopolysiloxane composition.

[0236] The molar ratio (SiH / Vi ratio) of the amount of SiH groups in component (E) to the amount of vinyl groups in component (A) was 33.

[0237] The composition was cured by the above method, and then the adhesion to a glass slide was measured by the above method, and the evaluation results are shown in Table 2.

[0238] Example 3

[0239] 16.31 parts by weight of vinyl-functional polydimethylsiloxane of component (A),

[0240] 6.99 parts by weight of methyl-terminated high molecular weight polydimethylsiloxane of component (A'),

[0241] 45.00 parts by weight of trimethylsilyl - terminated MQ resin of component B,

[0242] 23.30 parts by weight of toluene of component G,

[0243] 0.4 part by weight of trimethylsilyl - terminated poly(dimethylsiloxane - co - methylhydrogen) siloxane of component C,

[0244] 2.0 parts by weight of tetraethoxysilane of component D,

[0245] 0.2 part by weight of 1 - ethynyl - 1 - cyclohexanol of component F

[0246] Mix well at room temperature,

[0247] Then add 0.36 part by weight of a platinum - based hydrosilylation reaction catalyst of component E to the mixture to form a curable reactive organopolysiloxane composition.

[0248] The molar ratio (SiH / Vi ratio) of the amount of SiH groups in component (E) to the amount of alkenyl groups in component (A) is 37.

[0249] The composition is cured by the above - mentioned method, and then the adhesion to a glass slide is measured by the above - mentioned method, and the evaluation results are shown in Table 2.

[0250] Example 4

[0251] 13.98 parts by weight of vinyl - functional polydimethylsiloxane of component A,

[0252] 9.32 parts by weight of methyl - terminated high - molecular - weight polydimethylsiloxane of component A',

[0253] 45.00 parts by weight of trimethylsilyl - terminated MQ resin of component B,

[0254] 23.30 parts by weight of toluene of component G,

[0255] 0.4 part by weight of trimethylsilyl - terminated poly(dimethylsiloxane - co - methylhydrogen) siloxane of component C,

[0256] 2.0 parts by weight of tetraethoxysilane of component D,

[0257] 0.2 part by weight of 1 - ethynyl - 1 - cyclohexanol of component F

[0258] Mix well at room temperature,

[0259] Then, 0.36 parts by weight of a platinum-based hydrosilylation reaction catalyst of component (E) was added to the mixture to form a curable reactive organopolysiloxane composition.

[0260] The molar ratio (SiH / Vi ratio) of the amount of SiH groups in component (E) to the amount of vinyl groups in component (A) was 44.

[0261] The composition was cured by the above method, and then the adhesion to a glass slide was measured by the above method, and the evaluation results are shown in Table 2.

[0262] Example 5

[0263] 11.65 parts by weight of vinyl-functional polydimethylsiloxane of component (A),

[0264] 11.65 parts by weight of methyl-terminated high molecular weight polydimethylsiloxane of component (A'),

[0265] 45.00 parts by weight of trimethylsilyl-terminated MQ resin of component (B),

[0266] 23.30 parts by weight of toluene of component (G),

[0267] 0.4 parts by weight of trimethylsilyl-terminated poly(dimethylsiloxane-co-methylhydrogen) siloxane of component (C),

[0268] 2.0 parts by weight of tetraethoxysilane of component (D),

[0269] 0.2 parts by weight of 1-ethynyl-1-cyclohexanol of component (F)

[0270] They were thoroughly mixed at room temperature,

[0271] Then, 0.36 parts by weight of a platinum-based hydrosilylation reaction catalyst of component (E) was added to the mixture to form a curable reactive organopolysiloxane composition.

[0272] The molar ratio (SiH / Vi ratio) of the amount of SiH groups in component (E) to the amount of vinyl groups in component (A) was 52.

[0273] The composition was cured by the above method, and then the adhesion to a glass slide was measured by the above method, and the evaluation results are shown in Table 2.

[0274] Reference Example 1

[0275] 16.31 parts by weight of vinyl-functional polydimethylsiloxane of component (A),

[0276] 6.99 parts by weight of methyl-terminated high molecular weight polydimethylsiloxane of component (A'),

[0277] 65.37 parts by weight of a trimethylsilyl - terminated MQ resin of component B,

[0278] 23.30 parts by weight of toluene of component G,

[0279] 0.34 parts by weight of a trimethylsilyl - terminated poly(dimethylsiloxane - co - methylhydrogen) siloxane of component C,

[0280] 0.06 parts by weight of 1 - ethynyl - 1 - cyclohexanol of component F

[0281] Mix well at room temperature,

[0282] Then add 0.25 parts by weight of a platinum - based hydrosilylation reaction catalyst of component E to the mixture to form a curable reactive organopolysiloxane composition.

[0283] The molar ratio (SiH / Vi ratio) of the amount of SiH groups in component (E) to the amount of vinyl groups in component (A) is 32.

[0284] Cure the composition by the above - mentioned method, then measure the adhesion to the PMMA plate by the above - mentioned method, and show the evaluation results in Table 2.

[0285] Reference Example 2

[0286] 16.31 parts by weight of a vinyl - functional polydimethylsiloxane of component A,

[0287] 6.99 parts by weight of a methyl - terminated high - molecular - weight polydimethylsiloxane of component A',

[0288] 65.37 parts by weight of a trimethylsilyl - terminated MQ resin of component B,

[0289] 23.30 parts by weight of toluene of component G,

[0290] 0.11 parts by weight of a trimethylsilyl - terminated poly(dimethylsiloxane - co - methylhydrogen) siloxane of component C,

[0291] 0.06 parts by weight of 1 - ethynyl - 1 - cyclohexanol of component F

[0292] Mix well at room temperature,

[0293] Then add 0.25 parts by weight of a platinum - based hydrosilylation reaction catalyst of component E to the mixture to form a curable reactive organopolysiloxane composition.

[0294] The molar ratio (SiH / Vi ratio) of the amount of SiH groups in component (E) to the amount of alkenyl groups in component (A) is 10.

[0295] The composition was cured by the above method, and then the adhesion to the PMMA plate was measured by the above method, and the evaluation results thereof are shown in Table 2.

[0296] Table 2

[0297]

[0298]

[0299] *Adhesion measured relative to the PMMA plate.

[0300] As shown in Table 2, the compositions for forming a silicone-based PSA layer according to Examples 1 to 5 using tetraethoxysilane (TEOS) as a fixing additive provided an adhesion increase of 34% to 65% compared to the same compositions without TEOS (= component (C)). Specifically, the adhesions of Examples 1 and 2 compared to Comparative Example 1 (increased by 39% and 65%); Example 3 compared to Comparative Example 2 (increased by 34%); Example 4 compared to Comparative Example 3 (increased by 42%); and Example 5 compared to Comparative Example 4 (increased by 65%) showed that by using TEOS, the adhesion in the examples was significantly increased and / or improved compared to the corresponding comparative examples.

[0301] In addition, the SiH / vinyl ratios of Examples 1 - 5 and Comparative Examples 1 - 4 were in the range of 33 - 52. In Reference Examples 1 and 2, the SiH / vinyl ratios were 32 and 10, respectively. The peel adhesions of these two reference examples to PMMA were 2200 gf / inch, indicating good curing. However, in Comparative Example 5 with a SiH / vinyl ratio of 5.0, the adhesion value to PMMA was 440 gf / inch, where cohesive failure of the PSA occurred, indicating that a SiH / vinyl ratio > 5 is preferred for achieving the technical benefits in the present invention.

Claims

1. A composition for forming a silicone-based pressure-sensitive adhesive layer, the composition comprising components (A) to (E): (A) A linear organopolysiloxane having an average of more than 1 alkenyl group per molecule; (B) An organopolysiloxane resin in which the total content of hydroxyl groups and hydrolyzable groups is 2.0% by mass or less relative to all silicon atoms in the molecule; (C) An organohydrogenpolysiloxane having at least two Si-H bonds in the molecule; (D) At least one of a tetraalkoxysilane or a prepolymer thereof; and (E) A hydrosilylation reaction catalyst, wherein the mass ratio of component (B) to component (A) is in the range of 0.5 to 3.5, and based on the total mass of components (A) to (C), the amount of component (D) is in the range of 0.1% by mass to 9.0% by mass.

2. The composition for forming a silicone-based pressure-sensitive adhesive layer according to claim 1, wherein the component (D) is tetramethoxysilane, tetraethoxysilane, or a mixture thereof.

3. The composition for forming a silicone-based pressure-sensitive adhesive layer according to claim 1 or claim 2, where 50% to 100% by mass of the component (A) is (A1) a raw rubber-like alkenyl group-containing organopolysiloxane having a viscosity of 100,000 mPa·s or higher at 25°C or a plasticity value in the range of 50 to 200 as measured by the method described in JIS K6249, and the content of the vinyl (CH2=CH-) moiety of the alkenyl group is in the range of 0.005% by mass to 0.400% by mass; The component (B) is (B1) an organopolysiloxane resin consisting essentially of R 3 SiO 1 / 2 units and SiO 4 / 2 units, or a mixture thereof, where R is a monovalent organic group and 90 mol% or more of the R is an alkyl group or a phenyl group having 1 to 6 carbon atoms; the component (C) is present in an amount such that the molar ratio of the amount of SiH groups in the component (C) to the total amount of alkenyl groups in components (A) and (B) is 7 to 100; and the component (E) is a platinum-based catalyst and is present in an amount such that in the composition for forming the silicone-based pressure-sensitive adhesive without a solvent, the content of platinum-based metal in the solid content of the composition is in the range of 0.1 ppm to 200 ppm.

4. The composition for forming a silicone-based pressure-sensitive adhesive layer according to any one of claims 1 to 3, the composition further comprising (A') a linear organopolysiloxane that does not contain a carbon-carbon double bond-reactive group in the molecule.

5. The composition for forming a silicone-based pressure-sensitive adhesive layer according to claim 4, wherein 50% to 100% by mass of the component (A') is (A'1) a raw rubber-like organopolysiloxane having a viscosity of 100,000 mPa·s or higher at 25°C or a plasticity value in the range of 50 to 200 as measured by the method described in JIS K6249.

6. The composition for forming a silicone-based pressure-sensitive adhesive layer according to any one of claims 1 to 5, wherein 50% to 100% by mass of the component (A) is (A1) a raw rubber-like alkenyl group-containing organopolysiloxane having a viscosity of 100,000 mPa·s or higher at 25°C or a plasticity value in the range of 50 to 200 as measured by the method described in JIS K6249, and the content of the vinyl (CH2=CH-) moiety of the alkenyl group is in the range of 0.005% to 0.400% by mass; 50% to 100% by mass of the optional component (A') is (A'1) a raw rubber-like organopolysiloxane having a viscosity of 100,000 mPa·s or higher at 25°C or a plasticity value in the range of 50 to 200 as measured by the method described in JIS K6249; and the mass ratio range of component (A) to component (A') is from 100:0 to 40:

60.

7. The composition for forming a silicone-based pressure-sensitive adhesive layer according to any one of claims 1 to 6, wherein the component (C) is present in such an amount that the molar ratio of the amount of SiH groups in the component (C) to the total amount of alkenyl groups in components (A) and (B) is from 7 to 60.

8. The composition for forming a silicone-based pressure-sensitive adhesive layer according to any one of claims 1 to 7, wherein the adhesive strength of the pressure-sensitive adhesive layer having a thickness of 50 μm obtained by curing the composition, as measured by the 180° peel test method according to JIS Z 0237 at a tensile speed of 300 mm / min on a glass substrate, is more than 20% greater than the adhesive strength of the pressure-sensitive adhesive layer obtained from the same composition but without component (D).

9. The composition for forming a silicone-based pressure-sensitive adhesive layer according to any one of claims 1 to 8, wherein the adhesive strength of the pressure-sensitive adhesive layer having a thickness of 50 μm obtained by curing the composition, as measured by the 180° peel test method according to JIS Z 0237 at a tensile speed of 300 mm / min on a glass substrate, is in the range of 800 gf / inch to 3000 gf / inch.

10. A pressure-sensitive adhesive layer obtained by curing the composition for forming a silicone-based pressure-sensitive adhesive layer according to any one of claims 1 to 9.

11. A laminate comprising a pressure-sensitive adhesive layer obtained by curing the composition for forming a silicone-based pressure-sensitive adhesive layer according to any one of claims 1 to 9 on a film-like substrate.

12. The laminate according to claim 11, wherein a release layer for the pressure-sensitive adhesive layer is provided on one or two or more film-like substrates.

13. The laminate according to claim 11 or 12, the laminate comprising: a film-like substrate; a first release layer formed on the film-like substrate; A pressure-sensitive adhesive layer, which is formed by applying and curing a composition for forming a silicone-based pressure-sensitive adhesive layer according to any one of claims 1 to 9 on the release layer; and A second release layer, which is laminated on the pressure-sensitive adhesive layer.

14. An elastic adhesive member, which is obtained by curing a composition for forming a silicone-based pressure-sensitive adhesive layer according to any one of claims 1 to 9.

15. An electronic device or an electrical apparatus, which includes the elastic adhesive member according to the claim.

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