Silicone-based pressure-sensitive adhesive layer-forming composition and use thereof

Abstract

A silicone-based pressure-sensitive adhesive layer-forming composition comprising components (A) to (E), (A) a linear organopolysiloxane having an average of more than one alkenyl group per molecule; (B) an organopolysiloxane resin having a combined content of hydroxyl groups and hydrolyzable groups relative to all silicon atoms in the molecule of 2.0 mass% or less; (C) an organohydrogenpolysiloxane having at least two Si-H bonds per molecule; (D) at least one of a tetraalkoxysilane or a prepolymer thereof; and (E) a hydrosilylation reaction catalyst; the mass ratio of component (B) to component (A) is within the range of 0.5 to 3.5; and the amount of component (D) relative to the total mass of components (A) to (C) is within the range of 0.1 to 9.0 mass%. The silicone-based pressure-sensitive adhesive layer-forming composition has excellent curing properties through a hydrosilylation reaction, and can form a pressure-sensitive adhesive layer with improved adhesive strength, a lower Tg / elastic modulus at lower temperatures, and flexible properties.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) none.

[0002] FIELD OF THE INVENTION The present invention relates to a curable reactive organopolysiloxane composition that forms a pressure-sensitive adhesive layer (i.e., a silicone-based pressure-sensitive adhesive layer-forming composition) with higher adhesive strength by using at least one tetraalkoxysilane or a prepolymer of the tetraalkoxysilane as an anchor additive. The present invention also relates to a pressure-sensitive adhesive composition using the composition, as well as applications of the composition, such as laminates, electronic components, and display devices (including flexible displays, foldable displays, in-vehicle displays, touch panels, etc.). [Background technology]

[0003] Polysiloxane pressure-sensitive adhesive (PSA) compositions are superior to acrylic and rubber-based pressure-sensitive adhesive compositions in terms of electrical insulation, heat resistance, cold resistance, and adhesion to various substrates and adherends, and are therefore used in heat-resistant adhesive tapes, electrically insulating adhesive tapes, heat-sealing tapes, plating masking tapes, etc. These polysiloxane pressure-sensitive adhesive compositions are classified according to their curing mechanism into addition reaction curing types, condensation reaction curing types, peroxide curing types, etc. Addition reaction curing pressure-sensitive adhesive compositions are widely used because they cure rapidly when left at room temperature or when heated, and do not produce by-products.

[0004] Taking advantage of the above-mentioned characteristics of polysiloxane pressure-sensitive adhesive compositions, as well as their ability to achieve high transparency as needed, their application in the fields of advanced electronic materials and display elements such as smart devices has been studied in recent years. Such devices have a structure in which a film consisting of multiple layers, including an electrode layer and a display layer, is sandwiched between transparent substrates, and polysiloxane pressure-sensitive adhesive compositions with excellent heat resistance and cold resistance are expected to be effective in protecting the electrode layer and display layer and improving adhesion between the layers.

[0005] In particular, recent material development has required polysiloxane pressure-sensitive adhesive compositions that have a relatively low storage modulus (e.g., shear storage modulus G'), excellent curing properties, and sufficient adhesiveness for practical use over a wide temperature range, including as low as -20°C. For example, the present inventors have already proposed various silicone-based PSA (including optically clear adhesive (OCA)) layer-forming compositions and their uses in Patent Documents 1 to 4. In these patent documents, the present inventors proposed silicone-based PSA layers that have a lower Tg and a lower modulus at low temperatures.

[0006] However, it has been found that silicone-based PSA layers with low Tg or modulus tend to have reduced adhesive strength. This trade-off between adhesive strength and low Tg / modulus in silicone-based PSA layers poses a potential problem in that the silicone-based PSA layers cannot be used in some applications requiring strong adhesive strength in assembly / bonding layers or units in laminates, electronic devices (e.g., displays), and articles.

[0007] On the other hand, hydrolyzable silanes have been widely applied in curable silicone compositions as crosslinkers in condensation-curable silicones or as silane coupling agents as additives or treatments for several components (see Patent Documents 5 to 8). However, there has been no disclosure or suggestion of applying specific tetraalkoxysilane(s) to addition-curable silicone-based pressure-sensitive adhesive compositions to improve their adhesive strength.

[0008] Patent Documents 9 and 10 disclose addition-reaction-curable silicone adhesive compositions that may contain silanes such as vinyltriacetoxysilane and glycidoxypropyltrimethoxysilane. However, they neither disclose nor suggest the use of specific tetraalkoxysilanes as anchor additives to enhance adhesive strength. Furthermore, the PSA compositions disclosed in Patent Documents 9 and 10 fail to achieve low Tg or low modulus properties in the curable PSA layer. Furthermore, Patent Document 9 discloses that the molar ratio of Si-H bonds to alkenyl groups in the composition (i.e., the SiH / Vi ratio) is too low, resulting in cured PSA layers with low adhesion values ​​and prone to cohesive failure. In other words, they neither disclose nor suggest the selective use of tetraalkoxysilanes as anchor additives to resolve the trade-off between adhesive strength and low Tg / modulus in silicone PSA layers. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] International Publication No. 2020032286(A1) [Patent Document 2] International Publication No. 2020032287(A1) [Patent Document 3] International Publication No. 2020032285(A1) [Patent Document 4] International Publication No. 2022138913(A1) [Patent Document 5] U.S. Patent No. 20100059171(A1) [Patent Document 6] U.S. Patent No. 20140356620(A1) [Patent Document 7] JP 2000017246(A) [Patent Document 8] U.S. Patent No. 5,561,203(A) [Patent Document 9] International Publication No. 2021000279(A1) [Patent Document 10] International Publication No. 2020248181(A1) Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention has been made to solve the above problems, and its object is to provide a curable reactive organopolysiloxane composition that forms a pressure-sensitive adhesive layer with a low storage modulus (G') / Tg characteristic and excellent adhesive strength without impairing curability. Another object of the present invention is to provide the use of the curable reactive organopolysiloxane composition or a cured product thereof as a pressure-sensitive adhesive layer, as an elastic adhesive member with improved adhesive strength in various applications, and as equipment and devices equipped with these. [Means for solving the problem]

[0011] The present inventors have intensively investigated the above-mentioned problems and arrived at the present invention. Specifically, one object of the present invention is achieved by a specific hydrosilylation-curable pressure-sensitive adhesive layer-forming organopolysiloxane composition that contains at least one of a tetraalkoxysilane or a tetraalkoxysilane prepolymer as an anchor additive. Compared to a pressure-sensitive adhesive layer obtained from the same or a similar composition but not containing the tetraalkoxysilane or its prepolymer as an anchor additive, the pressure-sensitive adhesive layer of the present invention can exhibit adhesive strength that is more than 20% greater. Furthermore, the tetraalkoxysilane as an anchor additive does not impair the low Tg / elastic modulus characteristics of the silicone-based pressure-sensitive adhesive layer.

[0012] That is, the above-mentioned problems can be solved by using a silicone-based pressure-sensitive adhesive layer-forming composition containing components (A) to (E). (A) a linear organopolysiloxane having an average of more than one alkenyl group per molecule; (B) an organopolysiloxane resin having a total content of hydroxyl groups and hydrolyzable groups of 2.0 mass% or less relative to all silicon atoms in the molecule; (C) an organohydrogenpolysiloxane having at least two Si-H bonds in one molecule; (D) at least one of a tetraalkoxysilane or a prepolymer of a tetraalkoxysilane, and (E) a hydrosilylation reaction catalyst; The mass ratio of component (B) to component (A) is within the range of 0.5 to 3.5, and the amount of component (D) relative to the total mass of components (A) to (C) is within the range of 0.1 to 9.0 mass %.

[0013] In one embodiment according to the present disclosure, the silicone-based pressure-sensitive adhesive layer-forming composition further comprises (A') a linear organopolysiloxane that does not contain a carbon-carbon double bond-containing reactive group in the molecule. In a preferred embodiment of the present invention, at least a portion of components (A) and (A') is a crude rubber-like organopolysiloxane that has a viscosity at 25°C of 100,000 mPa s or more, or a plasticity in the range of 50 to 200 when measured according to the method described in JIS K6249.

[0014] Furthermore, the above-mentioned problems can be solved by using these silicone-based pressure-sensitive adhesive layer-forming compositions or their cured products as pressure-sensitive adhesive layers, using them as electronic materials or display device components, and making them into electronic components or display devices. [Effects of the Invention]

[0015] The present invention overcomes to some extent the trade-off between high adhesive strength and a low Tg or modulus of elasticity at low temperatures in silicone-based pressure-sensitive adhesive layers. That is, the silicone-based pressure-sensitive adhesive layer-forming composition of the present invention has excellent curing properties through a hydrosilylation reaction, improved adhesive strength, and can form a pressure-sensitive adhesive layer that has flexible properties such as a low Tg / modulus of elasticity at low temperatures, a low modulus of elasticity at small deformations, low stress at large deformations, and high creep compliance. Furthermore, the silicone-based pressure-sensitive adhesive layer-forming composition or a cured product thereof can be suitably used as a pressure-sensitive adhesive layer, electronic material, or display device member, and electrical or electronic components or display devices equipped with these satisfy the above-mentioned required properties. Therefore, the pressure-sensitive adhesive layer can be applied to substrates such as electronic components in a temperature range from low to room temperature, offering the advantage of ease of industrialization, which is expected to improve the performance of the resulting laminates, such as display devices. In particular, the present invention can provide a silicone-based pressure-sensitive adhesive layer with a low Tg or modulus of elasticity and high adhesive strength without affecting the rheological / viscoelastic properties of the silicone-based pressure-sensitive adhesive layer. The present invention is well suited to expanding the applications and potential markets for silicone-based pressure-sensitive adhesive layers, including optically clear adhesives (OCAs), that are applied to a variety of display devices and electronic articles. DETAILED DESCRIPTION OF THE INVENTION

[0016] [Silicone-based PSA-forming composition] First, we will describe the silicone-based pressure-sensitive adhesive (PSA) layer-forming composition of the present invention. The composition rapidly cures via a curing reaction that includes a hydrosilylation reaction to form a pressure-sensitive adhesive layer with improved adhesive strength and relatively low shear storage modulus G' and Tg at -20°C. Below, we will explain each component in the composition, the range of organopolysiloxane resins, the mass ratio of organopolysiloxane resin to linear organopolysiloxane, and the characteristics of the pressure-sensitive adhesive layer.

[0017] As described above, the composition according to the present invention is characterized by including at least one of tetraalkoxysilane or tetraalkoxysilane prepolymer as an anchor additive to improve adhesive strength 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 with improved adhesive strength, a low Tg / elastic modulus at low temperatures, and flexible properties.

[0018] In one embodiment of the present invention, the silicone-based PSA-forming composition comprises the following components (A) through (E): (A) a linear organopolysiloxane having an average of more than one alkenyl group per molecule; (B) an organopolysiloxane resin having a total content of hydroxyl groups and hydrolyzable groups of 2.0 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 of a tetraalkoxysilane, and (E) a hydrosilylation reaction catalyst; the mass ratio of component (B) to component (A) is within the range of 0.5 to 3.5; The content of component (D) relative to the total weight of components (A) to (C) is within the ranges of 0.1 to 9.0 mass%, 0.1 to 7.0 mass%, 0.1 to 5.0 mass%, 0.1 to 3.0 mass%, 0.1 to 1.0 mass%, 1.0 to 9.0 mass%, 1.0 to 7.0 mass%, 1.0 to 5.0 mass%, 1.0 to 3.0 mass%, 3.0 to 9.0 mass%, 3.0 to 7.0 mass%, 3.0 to 5.0 mass%, 5.0 to 9.0 mass%, 5.0 to 7.0 mass%, and 7.0 to 9.0 mass%.

[0019] Furthermore, in a further embodiment of the present invention, the silicone-based PSA-forming composition may further contain (A') a linear organopolysiloxane that does not contain a carbon-carbon double bond-containing reactive group in the molecule.

[0020] Furthermore, since the composition contains a hydrosilylation reaction catalyst, from the viewpoint of handleability, it may further contain a cure retarder (F), and may further contain other additives within a range that does not contradict the object of the present invention.

[0021] In the present invention, component (A) is a linear (i.e., chain) organopolysiloxane having an average of more than one alkenyl group per molecule, preferably 1.5 or more alkenyl groups per molecule, and more preferably 2.0 or more alkenyl groups per molecule. In some embodiments according to the present invention, the average number of alkenyl groups per molecule may be in the range of 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 the alkenyl group in component (A) include alkenyl groups having 2 to 10 carbon atoms, such as vinyl, allyl, butenyl, pentenyl, hexenyl, and heptenyl, with vinyl and hexenyl being particularly preferred. The bonding position of the alkenyl group in component (A) may be at the molecular chain terminal and / or molecular side chain. Component (A) may be a single component or a mixture of two or more different components.

[0022] Examples of silicon-bonded organic groups other than alkenyl groups in the organopolysiloxane of component (A) include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, and heptyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl and phenethyl; and halogenated alkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl, with methyl and phenyl groups being particularly preferred.

[0023] In the present invention, component (A) has a linear organopolysiloxane molecular structure, unlike component (B). For example, component (A) is preferably linear or partially branched linear, and may also contain a partially cyclic three-dimensional network. Preferably, the main chain of the organopolysiloxane is composed of repeating diorganosiloxane units (i.e., -SiO 2 / 2 Preferably, the diorganopolysiloxane is a linear or branched diorganopolysiloxane consisting of a triorganosiloxy unit (T or D unit) and both molecular chain terminals are blocked with triorganosiloxy groups. The siloxane units that provide the branched organopolysiloxane are T units or Q units, which will be described later.

[0024] Component (A) may be in the form of an oil or a crude rubber-like substance at room temperature, and preferably has a viscosity of 50 mPa·s or greater, particularly 100 mPa·s or greater, at 25° C. In particular, when the linear organopolysiloxane composition according to the present invention is a solvent-based composition, at least a portion of component (A) is (A1) a crude rubber-like alkenyl group-containing organopolysiloxane having a viscosity of 100,000 mPa·s or greater at 25° C. or a plasticity, measured in accordance with the method specified in JIS K6249 (the value obtained by applying a load of 1 kgf to a 4.2 g spherical sample at 25° C. for 3 minutes, reading the thickness to the nearest 1 / 100 mm, and multiplying the result by 100), in the range of 50 to 200, preferably 80 to 200, and more preferably 100 to 200.

[0025] To prevent poor contact, it is preferable to reduce or remove volatile or low-molecular-weight siloxane oligomers (e.g., octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), etc.) in the organopolysiloxane alkenyl groups. The amount can be designed as desired, but must be less than 1% by mass of the total component (A), less than 0.1% by mass for each siloxane oligomer, and, if necessary, reduced to near the detection limit.

[0026] There are no particular restrictions on the amount of alkenyl groups in component (A1), but the amount of vinyl (CH2=CH) moieties in the alkenyl groups in component (A1) (hereafter referred to as the "vinyl content") can be within a range of 0.005 to 0.400 mass%, preferably 0.005 to 0.300 mass%, and particularly preferably 0.005 to 0.200 mass%.

[0027] In some embodiments of the present invention, a component (A) having a lower viscosity than 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 used. Note that, apart from the viscosity, examples of component (A2) are the same as those of component (A1).

[0028] In the present invention, it is preferred that 50 mass % or more of component (A) is component (A1), a high-degree-of-polymerization alkenyl-containing organopolysiloxane, and it is particularly preferred that 75 to 100 mass % is component (A1). That is, when component (A) of the present invention is a combination of component (A1) (= a high-degree-of-polymerization alkenyl-containing organopolysiloxane) and component (A2) (= a low-degree-of-polymerization alkenyl-containing organopolysiloxane), the mass ratio of component (A1) to component (A2) is 50:50 to 100:0, preferably 75:25 to 100:0, and more preferably 75:25 to 90:10.

[0029] In the present invention, the organopolysiloxane resin of component (B) is an adhesion-imparting component that imparts adhesion to a substrate, and a low-temperature storage modulus and a practical range of adhesive strength are simultaneously achieved by using a mixture of organopolysiloxane resins in a specific ratio relative to component (A). More specifically, component (B) is an organopolysiloxane resin with a low average molecular weight, and the content of hydroxyl groups and hydrolyzable groups is reduced, making it less likely for hydrolysis and polymerization reactions to occur between components (B). By selectively using an organopolysiloxane resin with a low average molecular weight, the pressure-sensitive adhesive layer, which is the cured product, can achieve a desired storage modulus and a practical range of adhesive strength.

[0030] Specifically, component (B) is an organopolysiloxane resin in which the total content of hydroxyl groups and hydrolyzable groups relative to the total number of silicon atoms in the molecule is 2.0% by mass or less, 1.6% by mass or less, 1.5% by mass or less, or 1.2% by mass or less. The hydroxyl and hydrolyzable group contents of component (B) can be expressed by converting all of these functional groups into hydroxyl groups. In this case, when the mass % is calculated assuming that all hydrolyzable groups other than hydroxyl groups in the organopolysiloxane resin molecule are hydroxyl groups (OH), the total content of the hydroxyl groups and hydrolyzable groups can be expressed such that the content of hydroxyl groups and the hydrolyzable groups converted to hydroxyl groups in the organopolysiloxane resin molecule is 2.0% by mass or less, 1.6% by mass or less, 1.5% by mass or less, or 1.2% by mass or less. The hydroxyl group or hydrolyzable group is a group directly bonded to a silicon atom of a siloxane unit, such as a T unit or a Q unit, in the resin structure described below, and is obtained by hydrolyzing a silane or a silane derivative. Therefore, the content of hydroxyl groups or hydrolyzable groups can be reduced by hydrolyzing the synthesized organopolysiloxane resin with a silylating agent such as trimethylsilane.

[0031] In component (B), if the amount of hydroxyl groups or hydrolyzable groups exceeds the upper limit, a condensation reaction between organopolysiloxane resin molecules proceeds, and a high-molecular-weight organopolysiloxane resin structure is likely to form in the cured product. Such high-molecular-weight organopolysiloxane resins tend to impair the curability of the entire composition, which may result in insufficient curing of the composition at low temperatures, and the resulting pressure-sensitive adhesive layer may not have a storage modulus sufficient for practical use.

[0032] In the present invention, component (B) is an organopolysiloxane resin having a three-dimensional structure. For example, RSiO 2 / 2 Units (D units) and RSiO 3 / 2 units (T units) (wherein each R independently represents a monovalent organic group) and the content of hydroxyl groups or hydrolyzable groups is within the above range; a resin consisting only of T units and the content of hydroxyl groups or hydrolyzable groups is within the above range; RSiO 1 / 2Units (M units) and SiO 4 / 2 The resins include those consisting of units (Q units) and having a hydroxyl group or hydrolyzable group content within the above range. 1 / 2 Units (M units) and SiO 4 / 2 A resin (also called an MQ resin) is preferably used which is composed of units (Q units) and in which the total content of hydroxyl groups and hydrolyzable groups is preferably within the range of 0.0 to 1.6 mass % when all of these functional groups are converted to hydroxyl groups.

[0033] The monovalent organic group for R is preferably a monovalent hydrocarbon group having 1 to 10 carbon atoms, such as an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, a cycloalkyl group having 6 to 10 carbon atoms, a benzyl group, a phenylethyl group, a phenylpropyl group, etc. In particular, it is preferable that 90 mol % or more of R are alkyl groups having 1 to 6 carbon atoms or phenyl groups, and it is particularly preferable that 95 to 100 mol % of R are methyl groups or phenyl groups.

[0034] Preferably, component (B) is (B1)RSiO 1 / 2 Units and SiO 4 / 2 The organopolysiloxane resin or mixture thereof is essentially composed of RSiO units, in which R is a monovalent organic group and 90 mol % or more of the R are alkyl groups having 1 to 6 carbon atoms or phenyl groups. 1 / 2 Units (M units) and SiO 4 / 2 In the case of a resin composed of M units and Q units, the molar ratio of M units to Q units is preferably 0.5 to 2.0. This is because a molar ratio of less than 0.5 may result in a decrease in adhesive strength to the substrate, while a molar ratio of more than 2.0 may result in a decrease in cohesive strength of the material constituting the adhesive layer. Component (B) may also contain D units and / or T units to the extent that the properties of the present invention are not impaired. Furthermore, to prevent poor contact and the like, the amount of low-molecular-weight siloxane oligomers in these organopolysiloxane resins may be reduced or removed.

[0035] In the present invention, the weight-average molecular weight (Mw) of the organopolysiloxane resin that functions 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 standpoint, the Mw of component (B) determined by gel permeation chromatography (GPC) relative to standard polystyrene is 500 to 20,000 (g / mol), preferably 1,000 to 17,500 (g / mol), and most preferably 2,000 to 16,500 (g / mol).

[0036] [Mass ratio of component (B) to component (A)] The pressure-sensitive adhesive layer-forming organopolysiloxane composition according to the present invention is characterized in that the mass ratio of component (B) (organopolysiloxane resin) to component (A) (linear reactive siloxane component) is within a specific range. The mass ratio of component (B) to component (A), in combination with component (D) as a fixed additive, is within 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, when the chain organopolysiloxane (A') that does not contain a carbon-carbon double bond-containing reactive group in the molecule is optional, the mass ratio of component (B) to component (A) is within 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. On the other hand, when this composition contains component (A') and the mass ratio of component (A) to component (A') is within 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 within 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, as long as components (A) and (A') are used in the above mass ratio, the technical effects of the present invention can be achieved even if the mass ratio of component (B) to component (A) is within the range of more than 1.8 but less than 2.4.

[0037] When component (A') is not an essential component in the composition of the present invention, the mass ratio of component (B) to the total of components (A) and (A') is within the range of 0.9 to 1.8, and may also be within the range of 1.0 to 1.77, 1.2 to 1.6, or 1.4 to 1.5 to achieve the desired adhesive strength and storage modulus. Note that in the case of the mass ratio of component (B) to component (A), the additional use of component (A') is one of the preferred embodiments of the present invention, without impairing the technical effect of the present invention.

[0038] In contrast, when component (A') is an essential component in the composition of the present invention and the mass ratio of component (A) to component (A') is within the range of 95:5 to 60:40, the mass ratio of component (B) to the sum of components (A) and (A') is within 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 may also be within the range of 0.9 to 2.3 or within the range of 1.0 to 2.3.

[0039] In the present invention, component (C) is an organohydrogenpolysiloxane having two or more Si-H bonds per molecule, and serves as a crosslinking agent in the organopolysiloxane composition of the present invention. The molecular structure of component (C) is not particularly limited, and examples include linear, partially branched linear, branched, cyclic, and organopolysiloxane resin structures, with linear, partially branched linear, and organopolysiloxane resin structures being preferred. The bonding positions of the silicon-bonded hydrogen atoms are not particularly limited, and examples include molecular terminals, side chains, or both molecular terminals and side chains. The content of silicon-bonded hydrogen atoms is preferably 0.1 to 2.0% by mass, and more preferably 0.5 to 1.7% by mass.

[0040] 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; aryl groups, such as phenyl and tolyl; aralkyl groups, such as benzyl and phenethyl; and halogenated alkyl groups, such as 3-chloropropyl and 3,3,3-trifluoropropyl. Preferably, at least 50 mol% of the total group are alkyl groups having 1 to 8 carbon atoms or phenyl groups. From the standpoints of ease of production and compatibility with the above-mentioned preferred components (A) and (B), the other organic groups are preferably methyl or phenyl groups.

[0041] When component (C) of the present invention is an organopolysiloxane resin, such as an organohydrogenpolysiloxane, examples of which include organopolysiloxanes having the general formula: R'SiO 1 / 2 Siloxane units represented by the general formula: R'HSiO 1 / 2 and siloxane units represented by the formula: SiO 4 / 2Organopolysiloxane copolymers comprising siloxane units represented by the general formula: R'HSiO 1 / 2 and siloxane units represented by the formula: SiO 4 / 2 Organopolysiloxane copolymers consisting of siloxane units represented by the general formula: R'HSiO 1 / 2 and siloxane units represented by the formula: R'SiO 3 / 2 Organopolysiloxane copolymers comprising siloxane units represented by the general formula: R'HSiO 2 / 2 Siloxane units represented by the general formula: R'SiO 3 / 2 Siloxane units represented by the general formula: HSiO 3 / 2 and mixtures of two or more of these organopolysiloxanes. In the formula, R' is an alkyl group, aryl group, aralkyl group or halogenated alkyl group having 1 to 8 carbon atoms, and examples thereof are the same as those mentioned above.

[0042] Examples of component (C) include tris(dimethylhydrogensiloxy)methylsilane, tetra(dimethylhydrogensiloxy)silane, methylhydrogenpolysiloxane terminated at both ends with trimethylsiloxy groups, dimethylsiloxane / methylhydrogensiloxane copolymer terminated at both ends with trimethylsiloxy groups, dimethylsiloxane / methylhydrogensiloxane copolymer terminated at both ends with dimethylhydrogensiloxane groups, cyclic methylhydrogenoligosiloxane, cyclic methylhydrogensiloxane / dimethylsiloxane copolymer, methylhydrogensiloxane / diphenylsiloxane copolymer terminated at both ends with trimethylsiloxy groups, methylhydrogensiloxane / diphenylsiloxane / dimethylsiloxane copolymer terminated at both ends with trimethylsiloxy groups, hydrolysis condensate of trimethylsilane, (CH3)2HSiO 1 / 2 Units and SiO 4 / 2 Copolymer consisting of units, (CH3)2HSiO 1 / 2 Units, SiO 4 / 2 Units, and (C6H5)SiO 3 / 2Copolymer consisting of units, (CH3)2HSiO 1 / 2 Units and CH3SiO 3 / 2 Copolymers of units, as well as mixtures of two or more of these.

[0043] In the case of a linear structure, the molecular formula is RTMe2SiO(Me2SiO) q (HMeSiO) r Preferred is a methylhydrogenpolysiloxane represented by SiMe2RT (wherein 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). Two or more types of component (C) may be used in combination.

[0044] Similarly, the following organosiloxanes can be given as examples: In the formula, 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, b, c, d, and e are each positive numbers, and the sum of b, c, d, and e in one molecule is 1. HMe2SiO(Ph2SiO) m SiMe2H HMePhSiO(PhSiO) m SiMePhH HMePhSiO(PhSiO) m (MePhSiO) n SiMePhH HMePhSiO(PhSiO) m (Me2SiO) n SiMePhH (HMeSiO 1 / 2 ) b (PhSiO 3 / 2 ) c (HMePhSiO 1 / 2 ) b (PhSiO 3 / 2 ) c (HMePhSiO 1 / 2 ) b (HMe2SiO 1 / 2 ) c (PhSiO 3 / 2 )d (HMe2SiO 1 / 2 ) b (Ph2SiO2 / 2) c (PhSiO 3 / 2 ) d (HMePhSiO 1 / 2 ) b (Ph2SiO2 / 2) c (PhSiO 3 / 2 ) d (HMePhSiO 1 / 2 ) b (HMe2SiO 1 / 2 ) c (Ph2SiO2 / 2) d (PhSiO 3 / 2 ) e .

[0045] [SiH / Vi ratio] The composition of the present invention is hydrosilylation-curable, and the amount of component (C) used is not particularly limited as long as the composition can be sufficiently cured by a hydrosilylation reaction. However, the molar ratio (i.e., the amount of silicon-bonded hydrogen (SiH) groups in component (C) relative to the sum of the amount (substance amount) of alkenyl groups in component (A) and the amount (substance amount) of alkenyl groups in component (B) in the composition is preferably within the range of 7 to 300, 7 to 200, or 7 to 100, and may be within the range of 7 to 60, 7 to 50, or 7 to 40.

[0046] On the other hand, to improve adhesion to substrates such as glass, the number of SiH groups per molecule can be designed to be 10 to 20 or more, preferably greater than 20, and more preferably 22 or more. For example, the ratio of the amount of silicon-bonded hydrogen (SiH) groups in component (C) relative to the sum of the amount (amount) of alkenyl groups in component (A) and the amount (amount) of alkenyl groups in component (B) in the composition can be designed to be in the range of 10 to 60 or 10 to 50. If the amount of SiH groups is below the lower limit, the technical effect of improving adhesion to the substrate may not be achieved. On the other hand, if the amount of SiH groups exceeds the upper limit, the amount of unreacted curing agent remaining increases, which may adversely affect cured physical properties such as brittleness of the cured product or cause problems such as gas generation. However, even if the SiH / Vi ratio of the composition is outside the above range, a pressure-sensitive adhesive layer sufficient for practical use can be formed.

[0047] [Hydrosilylation reaction catalyst] The organopolysiloxane composition of the present invention contains a hydrosilylation catalyst. Examples of hydrosilylation catalysts include platinum-based catalysts, rhodium-based catalysts, and palladium-based catalysts. Platinum-based catalysts are preferred because they significantly accelerate the curing of the composition. Examples of platinum-based catalysts include platinum fine powder, chloroplatinic acid, alcohol solutions of chloroplatinic acid, platinum-alkenylsiloxane complexes, platinum-olefin complexes, and platinum-carbonyl complexes. Platinum-alkenylsiloxane complexes are particularly preferred. Examples of alkenylsiloxanes include 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, alkenylsiloxanes in which some of the methyl groups of these alkenylsiloxanes have been substituted with groups selected from the group consisting of nitrile, amide, dioxolane, sulfolane, ethyl, and phenyl, and alkenylsiloxanes in which the vinyl groups of these alkenylsiloxanes have been substituted with allyl, hexenyl, or the like. 1,3-divinyl-1,1,3,3-tetramethyldisiloxane is particularly preferred because of the good stability of the platinum-alkenylsiloxane complex. Non-platinum metal catalysts such as iron, ruthenium, and iron / cobalt can be used as catalysts to promote the hydrosilylation reaction.

[0048] In the present invention, the content of the hydrosilylation catalyst is not particularly limited, but the amount of platinum-based metal relative to the total solids content in the composition (i.e., excluding the solvent) is within the range of 0.1 to 200 ppm, and may be within the range of 0.1 to 150 ppm, 0.1 to 100 ppm, or even 0.1 to 50 ppm. Here, platinum-based metals refer to Group VIII metal elements consisting of platinum, rhodium, palladium, ruthenium, and iridium. However, for practical purposes, it is preferable that the content of platinum metal excluding the ligands of the hydrosilylation catalyst be within the above range. The solids content refers to the components that form a cured layer when the organopolysiloxane composition of the present invention is cured (mainly the base resin, adhesion-imparting component, crosslinking agent, catalyst, and other non-volatile components), but does not include volatile components such as the solvent that volatilizes during heat curing.

[0049] When the platinum-based metal content in the organopolysiloxane composition of 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, discoloration or coloring of the transparent pressure-sensitive adhesive layer can be suppressed, particularly after curing, when heated, or when exposed to high-energy rays such as ultraviolet rays. On the other hand, from the viewpoint of the curability of the organopolysiloxane composition, the platinum-based metal content should be 0.1 ppm or more; if it is less than this lower limit, it may cause poor curing.

[0050] [Component (D) as anchor additive] Component (D) is at least one tetraalkoxysilane or tetraalkoxysilane prepolymer, which is an anchor additive for the silicone-based PSA composition of the present invention, improving adhesive strength without affecting the rheological / viscoelastic properties of the silicone-based pressure-sensitive adhesive layer. The rheological / viscoelastic properties of a cured silicone PSA layer are generally determined by its crosslinked polymer structure (including polymer chain length), resin structure (including silicone resin unit and Mw), and the molar ratio therein, resulting in a trade-off between low Tg or elastic modulus and high adhesive strength. However, in the present invention, by using a tetraalkoxysilane or tetraalkoxysilane prepolymer as an anchor additive, it is possible to increase only adhesive strength without affecting the low Tg or elastic modulus properties of the cured silicone PSA layer.

[0051] In a preferred embodiment of the present invention, the adhesive strength of a 50 μm-thick pressure-sensitive adhesive layer obtained by curing the composition is more than 20%, preferably 30% to 80%, greater than the adhesive strength of a pressure-sensitive adhesive layer obtained from the same composition but not containing component (D), when measured on a glass substrate at a tensile speed of 300 mm / min using the 180-degree peel test method in accordance with JIS Z 0237. Furthermore, when measured by the same method, the adhesive strength of the pressure-sensitive adhesive layer can be in the range of 800 to 3000 gf / inch, preferably 800 to 2000 gf / inch, and more preferably 800 to 1500 gf / inch, with a low Tg or modulus.

[0052] To achieve higher adhesive strength, component (D) must be at least one tetraalkoxysilane or tetraalkoxysilane prepolymer, such as tetramethoxysilane, tetraethoxysilane, or a mixture thereof. Tetraalkoxysilane prepolymers include complete or partial condensation products of the tetraalkoxysilane. Substituting other silanes, such as glycidoxypropyltrimethoxysilane or vinyltrimethoxysilane, for the tetraalkoxysilane cannot improve or enhance adhesive strength without affecting the rheological / viscoelastic properties of the silicone-based pressure-sensitive adhesive layer. Furthermore, to achieve sufficient adhesive strength, the amount of component (D) relative to the total mass of components (A) to (C) is in the range of 0.1 to 9.0 mass%, preferably 0.2 to 7.0 mass%, and more preferably 0.5 to 5.0 mass%, assuming a mass ratio of component (B) to component (A) of 0.5 to 3.5. If the amount of component (D) is less than the above lower limit, the technical effect of improving adhesion to the substrate may not be fully achieved. In contrast, if the amount of component (D) exceeds the upper limit, the excess amount of component (D) may adversely affect the cured physical properties.

[0053] In the present invention, component (F) is a cure retarder (=cure inhibitor) that is incorporated to inhibit the crosslinking reaction between the alkenyl groups in the composition and the SiH groups in component (C), thereby extending the usable life at room temperature and improving storage stability. Therefore, in practice, component (F) may be added to the pressure-sensitive adhesive layer-forming organopolysiloxane composition of the present invention.

[0054] Specific examples of component (F) include acetylene compounds, ene-yne ​​compounds, organic nitrogen compounds, organic phosphorus compounds, and oxime compounds. Specific examples include alkyne alcohols such as 3-methyl-1-butyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, 3-methyl-1-pentyn-3-ol, 1-ethynyl-1-cyclohexanol, and phenylbutanol; ene-yne ​​compounds such as 3-methyl-3-penten-1-yne and 3,5-dimethyl-1-hexyn-3-yne; methylalkenylcyclosiloxanes such as 2-ethynyl-4-methyl-2-pentene, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, and 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane; and benzotriazole.

[0055] From the viewpoint of the curing behavior of the composition, the pressure-sensitive adhesive layer-forming organopolysiloxane composition of the present invention is curable at 80 to 200°C, and preferably exhibits a viscosity increase of no more than 1.5 times after 8 hours at room temperature following the composition's preparation. Suppressing viscosity increase is important from the viewpoints of ease of handling, pot life, and post-curing properties. Even if a large amount of excess component (C) is contained and the platinum-based metal content is optionally low, curability can be ensured by curing at a high temperature above a certain level (80 to 200°C). Such a composition can be achieved by selecting an appropriate combination and amounts of the above-mentioned components, hydrosilylation catalyst, and component (F).

[0056] In addition to the preferred components (A) and (B), the organopolysiloxane composition of the present invention may contain an organic solvent as a solvent. The type and amount of organic solvent can be adjusted taking into account factors such as coating workability. Exemplary organic solvents include aromatic hydrocarbon solvents such as toluene, xylene, and benzene; aliphatic hydrocarbon solvents such as heptane, hexane, octane, and isoparaffin; ester solvents such as ethyl acetate and isobutyl acetate; ether solvents such as diisopropyl ether and 1,4-dioxane; chlorinated aliphatic hydrocarbon solvents such as trichloroethylene, perchloroethylene, and methylene chloride; and volatile oil solvents. Two or more types can be combined depending on the wettability of the sheet-like substrate. The amount of organic solvent is preferably an amount that allows the mixture of components (A) to (C) to be uniformly applied to the surface of the sheet-like substrate. For example, the amount may be 5 to 3,000 parts by mass per 100 parts by mass of the total amount of components (A), (B), and (C).

[0057] The organopolysiloxane composition of the present invention may optionally contain components other than those described above, provided that the effects of the present invention are not impaired. For example, the composition may contain an adhesion promoter; a non-reactive organopolysiloxane such as polydimethylsiloxane or polydimethyldiphenylsiloxane; an antioxidant such as a phenol-type, quinone-type, amine-type, phosphorus-type, phosphite-type, sulfur-type, or thioether-type antioxidant; a flame retardant such as a phosphate ester-type, halogen-type, phosphorus-type, or antimony-type; and one or more antistatic agents such as cationic surfactants, anionic surfactants, or nonionic surfactants. In addition to these components, pigments, dyes, inorganic fine particles (e.g., reinforcing fillers, dielectric fillers, conductive fillers, or thermally conductive fillers), etc., may also be optionally mixed.

[0058] [(A') Linear organopolysiloxane that does not contain a carbon-carbon double bond-containing reactive group in the molecule] The organopolysiloxane composition of the present invention can contain a non-reactive organopolysiloxane, such as polydimethylsiloxane or polydimethyldiphenylsiloxane, that does not contain a carbon-carbon double bond-containing reactive group, such as an alkenyl group, an acrylic group, or a methacrylic group. As a result, the loss factor (tan δ), storage modulus (G'), loss modulus (G"), and adhesive properties of the pressure-sensitive adhesive layer can be improved. For example, the loss factor of the pressure-sensitive adhesive layer can be increased by using a hydroxyl-terminated polydimethylsiloxane, or a trimethylsiloxy-terminated polydimethylsiloxane or polydimethyldiphenylsiloxane, and such compositions are within the scope of the present invention.

[0059] Preferably, component (A') is (A'1) a crude rubber-like organopolysiloxane having a viscosity at 25°C of 100,000 mPa·s or more, or a plasticity in the range of 50 to 200 when measured according to the method described in JIS K6249.

[0060] In the most preferred embodiment of the present invention, assuming that component (D) is used as an anchor additive to improve the adhesive strength of the cured PSA layer, both component (A) and component (A') are 50 to 100 mass% raw rubber-like organopolysiloxanes having high viscosity or plasticity. Specifically, in a preferred embodiment of the present invention, 50 to 100 mass% of component (A) is (A1) a crude rubber-like alkenyl group-containing organopolysiloxane having a viscosity of 100,000 mPa s or more at 25°C or a plasticity of 50 to 200 when measured according to the method specified in JIS K6249, and a vinyl (CH═CH—) moiety content of alkenyl groups of 0.005 to 0.400 mass%, and 50 to 100 mass% of the optional component (A′) is (A′1) a crude rubber-like organopolysiloxane having a viscosity of 100,000 mPa s or more at 25°C or a plasticity of 50 to 200 when measured according to the method specified in JIS K6249, and the mass ratio of component (A) to component (A′) in the composition is 100:0 to 40:60.

[0061] The silicone-based PSA-forming composition can be prepared by any method, including uniformly mixing the components together, adding a solvent if necessary, and mixing at a temperature of 0 to 200°C using a known mixer or kneader.

[0062] [Formation of adhesive layer using the silicone-based PSA-forming composition] The silicone-based PSA-forming composition forms a cured adhesive layer when applied to a substrate, and forms a cured product by heating at a temperature of 80 to 200° C., preferably 90 to 190° C. Coating methods include, for example, gravure coating, offset coating, offset gravure, roll coating, reverse roll coating, air knife coating, curtain coating, and comma coating.

[0063] Cured adhesive layers from the silicone-based PSA-forming compositions are disposed between functional layers to bond / assemble the layers in the electronic articles of the present invention.

[0064] [Storage modulus and other viscoelastic properties] The silicone-based PSA-forming composition according to the present invention has a pressure-sensitive adhesive layer (obtained by curing) with a shear storage modulus G' at -20°C in the range of 0.01 to 2.0 MPa, and the storage modulus G' may be in the range of 0.02 to 1.5 MPa, or 0.03 to 1.2 MPa; a storage modulus G' in the range of 0.04 to 1.0 MPa is also preferably included within the scope of the present invention. The organopolysiloxane composition for forming a pressure-sensitive adhesive layer according to the present invention has a relatively low storage modulus G' at low temperatures and possesses the above-mentioned practical adhesive strength, making it suitable for use in forming elastic adhesive members, as components for electronic and electrical devices (speakers, transducers, etc.), and also suitable for use in the fields of advanced electronic materials and display elements such as smart devices.

[0065] The storage modulus (G') of the pressure-sensitive adhesive layer according to the present invention can be measured by a known measurement method. For example, it can be measured using a storage modulus (G') viscoelasticity measuring device MCR301 (manufactured by Anton Paar). Using a disk-shaped sample with a diameter of approximately 8 mm and a thickness of approximately 0.5 to 1 mm, and 8 mm parallel plates, the measurement can be performed at a frequency of 1 Hz, a strain of 0.1%, a heating rate of 3°C / min, and a temperature of -20°C within the operating temperature range of -40°C to 100°C.

[0066] The pressure-sensitive adhesive layer according to the present invention may have a storage modulus G' at 1.0 Hz at -20°C that is at least three times the storage modulus G' at 1.0 Hz at 25°C.

[0067] [Transparency, color tone, or coloring and discoloration properties of the pressure-sensitive adhesive layer] The silicone-based PSA layer of the present invention may be substantially transparent, translucent, or opaque, and its transparency can be designed according to the intended use of the interlayer adhesive layer. For example, as an interlayer pressure-sensitive adhesive layer applied to a display device of the present invention, a 10-1000 μm thick film-like cured product obtained by curing the silicone-based PSA-forming composition is preferably visually transparent and preferably does not contain a coloring additive such as carbon black. Furthermore, when the pressure-sensitive adhesive layer for a display device formed from a 100 μm thick cured layer is visually transparent, the transmittance of light at a wavelength of 450 nm, when the value for air is taken as 100%, is more objectively 80% or more, preferably 90% or more, and may even be designed to be 95% or more. On the other hand, for bonding electrical or electronic components that do not require light transmittance, a translucent to opaque pressure-sensitive adhesive layer may be used, and filler components or additives that impair colorability or light transmittance may be used depending on the required characteristics other than light transmittance.

[0068] In addition to the transparency, the adhesive layer can be designed to prevent the cured product from becoming discolored by optionally reducing the content of platinum-based metals in the cured layer. Specifically, the L defined in JIS Z 8729 immediately after curing of a 100 μm-thick cured layer obtained by curing the organopolysiloxane composition of the present invention is * a * b * b measured in the color system * The value of b can be set to 0.15 or less to 0.10 or less. * Having a value of 0.1 means that the cured layer is substantially transparent and not yellow in color.

[0069] The cured layer of the present invention can be designed so that its color tone does not change significantly, and in particular, does not cause the problem of yellowing, even when exposed to high temperatures or high-energy rays such as ultraviolet rays for a long period of time. Specifically, in any of the following evaluations, a 100 μm-thick cured layer obtained by curing the organopolysiloxane composition of the present invention has a color tone that does not change significantly, and does not cause the problem of yellowing. * a * b * b measured in the color system * The change in value (Δb * ) can be designed to be 0.20 or less, preferably 0.15 or less. * is the absolute value of the change in value. (1) Heat aging evaluation: The cured layer was aged at 105°C for 300 hours. (2) High-energy ray irradiation: The hardened layer sample is irradiated with high-energy ray with an intensity of 12 mW / cm at 365 nm. 2 and the intensity at 254 nm is 3.5 mW / cm 2 The sample is irradiated with ultraviolet light at room temperature for 75 hours using a mercury lamp (for example, Optical Module X manufactured by Ushio Electric Co., Ltd.).

[0070] [Use as a pressure-sensitive adhesive layer] The cured product of the present invention can be used particularly as a pressure-sensitive adhesive layer. In addition, in order to improve adhesion to an adherend, the surface of the pressure-sensitive adhesive layer or the substrate may be subjected to surface treatment such as primer treatment, corona treatment, etching treatment, plasma treatment, etc. However, since the pressure-sensitive adhesive layer according to the present invention has excellent adhesion to substrates of display devices, etc., as described above, these steps can be added as necessary to further improve adhesion to the adherend, and higher production efficiency can be achieved by omitting these steps.

[0071] The curable organopolysiloxane composition of the present invention can be cured by applying it to a release liner, heating it under the temperature conditions described above, peeling off the release liner, and applying the composition to a film-like substrate, tape-like substrate, or sheet-like substrate (hereinafter referred to as a "film-like substrate"), or by applying it to a film-like substrate and then heating and curing it under the temperature conditions described above to form a pressure-sensitive adhesive layer on the surface of the substrate. Laminates having a cured layer, particularly 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, bandages, low-temperature supports, transfer films, labels, emblems, decorative and explanatory signs, and the like. Furthermore, the cured layer obtained by curing the organopolysiloxane composition of the present invention can be used in the assembly of automobile parts, toys, electronic circuits, keyboards, and the like. Alternatively, the cured layer, particularly a film-like pressure-sensitive adhesive layer, formed by curing the organopolysiloxane composition of the present invention can be used in the construction and use of laminated touch screens or flat panel displays.

[0072] Exemplary types of substrates include paperboard, cardboard, clay-coated paper, polyolefin-laminated paper, particularly polyethylene-laminated paper, synthetic resin films and sheets, natural fiber woven materials, synthetic fiber woven materials, artificial leather woven materials, and metal foils. Synthetic resin films and sheets are particularly preferred, and examples of synthetic resins include polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polycarbonate, polyethylene terephthalate, cyclopolyolefin, nylon, and the like. When heat resistance is required, heat-resistant synthetic resin films such as polyimide, polyether ether ketone, polyethylene naphthalate (PEN), liquid crystal polyacrylate, polyamide imide, and polyether sulfone are particularly preferred. On the other hand, for applications requiring visibility, such as display devices, transparent substrates, specifically transparent materials such as polypropylene, polystyrene, polyvinylidene chloride, polycarbonate, and polyethylene terephthalate are preferred.

[0073] The substrate is preferably a film- or sheet-like substrate. Its thickness is not particularly limited and can be designed to a desired thickness depending on the application. Furthermore, in order to improve adhesion between the support film and the pressure-sensitive adhesive layer, a support film that has been subjected to a primer treatment, corona treatment, etching treatment, or plasma treatment may be used. Furthermore, the surface of the film-like substrate opposite the pressure-sensitive adhesive layer may be subjected to a surface treatment, such as a treatment for scratch prevention, stain prevention, fingerprint prevention, glare prevention, anti-reflection, or anti-static treatment.

[0074] As a method for applying the composition to a substrate, any known method used for forming a cured layer, such as 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 flow coater or the like, comma coating, or Mayer bar coating, can be used without any limitation.

[0075] The coating amount can be designed to a desired thickness depending on the application, such as a display device, and the thickness of the pressure-sensitive adhesive layer after curing may be, for example, 1 to 1000 μm, 5 to 900 μm, or 10 to 800 μm, but is not limited to these.

[0076] The pressure-sensitive adhesive layer according to the present invention may be a single layer or a multilayer structure in which two or more pressure-sensitive adhesive layers are laminated, depending on the required properties. Multiple pressure-sensitive adhesive layers may be formed by bonding pressure-sensitive adhesive films (formed for each film), or the step of applying a pressure-sensitive adhesive layer-forming organopolysiloxane composition onto a film substrate (including a release layer) or the like and curing the composition may be carried out multiple times.

[0077] The pressure-sensitive adhesive layer according to the present invention may, in addition to its adhesive or cohesive function between members, also serve as another functional layer selected from a dielectric layer, a conductive layer, a heat dissipation layer, an insulating layer, a reinforcing layer, etc. Furthermore, as an interlayer silicone-based PSA layer, in addition to its adhesive or cohesive function between members, the silicone-based PSA layer of the present invention can also be used as a damping / shock absorbing layer.

[0078] Preferably, the interlayer adhesive layer has both an assembly / bonding layer function and a damping / impact-absorbing layer function, so that an electronic article having a silicone-based PSA layer of the present invention does not need to have an additional interlayer damping / impact-absorbing layer disposed between the two functional layers. Due to this dual-functional feature of the interlayer adhesive layer, electronic articles can be constructed through the present invention without using any additional interlayer damping / impact-absorbing layer other than the interlayer adhesive layer of the present invention between the two functional layers.

[0079] In a preferred embodiment, the electronic article having the silicone-based PSA layer of the present invention as an interlayer adhesive layer is an LED or OLED display device and its module, which has a structure in which a transparent display unit is directly bonded or assembled to other functional units using an interlayer adhesive layer, and the interlayer adhesive layer is a single adhesive / assembly layer sandwiched between the units in the display device. Since the display device having the silicone-based PSA can be designed to include substantially no additional interlayer damping / shock absorbing layers except for the interlayer adhesive layer of the present invention (i.e., omitting thick, multi-layer damping / shock absorbing layers from the device), the overall thickness of the display can be thinner and lighter than conventional devices.

[0080] When the cured layer obtained by curing the organopolysiloxane composition of the present invention is a pressure-sensitive adhesive layer, particularly a pressure-sensitive adhesive layer, the cured layer is preferably treated as a laminate film releasably adhered to a film substrate equipped with a release layer having release coating capability. The release layer is also called a release liner, separator, release layer, or release coating layer, and is preferably a release layer having release coating capability using a silicone-based release agent, a fluorine-based release agent, an alkyd-based release agent, or a fluorosilicone-based release agent. It may also be formed as a substrate itself, which is less likely to adhere to the resin sheet for pressure-sensitive adhesive layers of the present invention, by physically forming fine irregularities on the surface of the substrate. In particular, in the laminate of the present invention, a release layer obtained by curing a fluorosilicone-based release agent is preferably used as the release layer.

[0081] The cured product obtained by curing the organopolysiloxane composition of the present invention possesses both viscoelasticity and adhesive strength as described above, making it useful as an elastic adhesive member for various electronic devices and electrical devices. It is particularly useful as an electronic material, a display device member, or a transducer (including sensors, speakers, actuators, and generators). The cured product is preferably used as a member for electronic components or display devices. The cured product of the present invention may be transparent or opaque. However, a film-like cured product, particularly a substantially transparent pressure-sensitive adhesive film, is particularly suitable as a member for display panels and displays, and is particularly useful for touch panel applications, where devices, particularly electronic devices, can be operated by touching the screen with a fingertip or the like. Furthermore, because an opaque elastic adhesive layer does not require transparency, it is particularly useful for film- or sheet-like members used in sensors, speakers, actuators, and the like, where a certain degree of elasticity and flexibility is required for the adhesive layer itself.

[0082] In particular, the pressure-sensitive adhesive layer obtained by curing the organopolysiloxane composition of the present invention can achieve adhesive properties equivalent to those of conventional silicone-based pressure-sensitive adhesive layers, and can improve adhesion to substrates such as display devices without causing problems such as poor curing or reduced curing properties.

[0083] [Display panel or display component] The cured product obtained by curing the organopolysiloxane composition of the present invention can be used in the construction and application of laminated touch screens and flat panel displays, and the specific method of use thereof can be any known method for using pressure-sensitive adhesive layers (particularly silicone PSAs) without any particular restrictions.

[0084] For example, a cured product obtained by curing the organopolysiloxane composition of the present invention can be used as the optically transparent silicone-based pressure-sensitive adhesive film or adhesive layer described in the aforementioned JP 2014-522436 W and JP 2013-512326 W in the production of display devices such as touch panels. Specifically, a cured product obtained by curing the organopolysiloxane composition of the present invention can be used without particular limitation as the adhesive layer or adhesive film described in JP 2013-512326 W.

[0085] As an example, the touch panel according to the present invention may be a touch panel including a substrate such as a conductive plastic film having a conductive layer formed on one surface thereof, and a cured layer obtained by curing the curable organopolysiloxane composition of the present invention, attached to the side on which the conductive layer is formed or the surface opposite thereto. The substrate is preferably a sheet-like or film-like substrate, such as a resin film or a glass plate. The conductive plastic film may also be a resin film or a glass plate, particularly a polyethylene terephthalate film, having an ITO layer formed on one surface thereof. These are disclosed in the aforementioned JP 2013-512326 W and the like.

[0086] Furthermore, the cured product obtained by curing the organopolysiloxane composition of the present invention may be used as an adhesive film for polarizing plates used in the production of display devices such as touch panels, or may be used as a pressure-sensitive adhesive layer used to bond a touch panel to a display module as described in JP 2013-065009 A.

[0087] Industrial Applicability The uses of the silicone-based pressure-sensitive adhesive layer-forming composition of the present invention and the cured product obtained by curing the composition are not limited in any way to those disclosed above, and an adhesive film comprising a cured product obtained by curing the composition can be used in various display devices for displaying characters, symbols, and images, such as television sets, computer monitors, monitors for personal digital assistants, surveillance monitors, video cameras, digital cameras, mobile phones, personal digital assistants, instrument panel displays for automobiles, etc., instrument panel displays for various meters, devices, and equipment, automatic ticket machines, automatic teller machines, in-vehicle display devices, in-vehicle transmission screens, etc. The surface shape of such display devices may not be flat, but may be curved or bent, and examples thereof include various flat panel displays (FPDs), as well as curved displays and curved transmission screens used in automobiles (including electric vehicles) and aircraft, etc. Furthermore, these display devices can display icons for executing functions or programs on a screen or display, notification indicators for emails, programs, etc., and operation buttons for various devices such as car navigation devices, speaker membranes, audio devices, and air conditioners, and have a touch panel function that allows input operations to be added by touching these icons, notification indicators, or operation buttons with a finger. The composition can be used in display devices such as CRT displays, liquid crystal displays, plasma displays, organic electroluminescence displays, inorganic electroluminescence displays, LED displays, surface-emitting diode (SED) displays, and field emission displays (FED) displays, as well as devices such as touch panels using these display devices. Furthermore, the cured product obtained by curing the composition has excellent adhesiveness and viscoelastic properties and can be used as a sealing layer or adhesive layer for secondary batteries, fuel cells, and solar cell modules, as well as a film- or sheet-like member for transducers (including sensors, speakers, actuators, etc.).

[0088] The pressure-sensitive adhesive layer obtained by curing the silicone-based pressure-sensitive adhesive layer-forming composition of the present invention not only has excellent adhesion to substrates such as various display devices, but is also substantially transparent and does not suffer from problems such as poor curing or reduced curing properties. Therefore, the pressure-sensitive adhesive layer is suitable for use in vehicle display devices that provide good visibility and operability of displayed content over long periods of time, particularly vehicle display devices having curved screens or curved displays and optionally equipped with touch panel functionality. For example, vehicle display devices equipped with curved display surfaces are disclosed in JP 2017-047767 A, JP 2014-182335 A, JP 2014-063064 A, JP 2013-233852 A, etc. However, the pressure-sensitive adhesive layer of the present invention can be suitably used as or replace part or all of the adhesive layer or pressure-sensitive adhesive layer required to be transparent in these documents. Furthermore, with regard to the pressure-sensitive adhesive layer-forming organopolysiloxane composition of the present invention, it goes without saying that currently used adhesive layers and pressure-sensitive adhesive layers that require transparency can also be used in place of other known curved display devices, and in order to further utilize the advantages of the adhesive of the present invention, it is preferable to adjust the design of the display device and the thickness of the components using known techniques.

[0089] The transparent film substrate provided with the pressure-sensitive adhesive layer of the present invention can be used for purposes such as preventing scratches, dirt, fingerprints, static electricity, glare, and peeping on the display surface. [Example]

[0090] These examples are intended to illustrate the present invention to those skilled in the art and should not be construed as limiting the scope of the invention as defined in the claims. Note that "cured" in the examples, comparative examples, and reference examples means that each composition was fully cured under the respective curing conditions.

[0091] The materials used in these examples are listed in Table 1. The materials for the curable reactive organopolysiloxane composition are listed in Table 2. The viscosity and plasticity of each component were measured at room temperature using the following methods.

[0092] (viscosity) Viscosity (mPa.s) is a value measured using a rotational viscometer conforming to JIS K7117-1, and kinematic viscosity (mm 2 / s) is a value measured using an Ubbelohde viscometer in accordance with JIS Z8803.

[0093] (Plasticity) The plasticity was expressed as a value measured in accordance with the method specified in JIS K 6249 (the thickness when a 1 kgf load was applied to a 4.2 g spherical sample at 25°C for 3 minutes was read to the nearest 1 / 100 mm, and this value was multiplied by 100).

[0094] [Table 1]

[0095] Preparation of Silicone-Based PSA-Forming Compositions The silicone-based PSA formulations described in each of the Examples, Comparative Examples, and Reference Examples were prepared using the ingredients shown in Table 1. The formulations and adhesive strengths of the Examples, Comparative Examples, and Reference Examples are also summarized in Table 2.

[0096] (Measurement of molecular weight of organopolysiloxane component) The weight average molecular weight (Mw) and number average molecular weight (Mn) of organopolysiloxane components such as organopolysiloxane resins were determined in terms of standard polystyrene using a Waters gel permeation chromatography (GPC) and tetrahydrofuran (THF) as a solvent.

[0097] (Measurement of hydroxyl group (OH) content in organopolysiloxane resin) Using a Bruker ACP-30029 Si NMR spectrometer equipped with a glass-free probe, Si(OH)O, which appears at -93 to -103.5 ppm, with the chemical shift of tetramethylsilane set at 0 ppm, was measured. 2 / 3 The molar content was determined from the abundance ratio of the unit to all silicon atoms, and then converted into mass % of hydroxyl groups (OH) in the organopolysiloxane resin. Note that in the following examples, the organopolysiloxane resin does not contain hydrolyzable groups other than hydroxyl groups.

[0098] (Adhesion force measurement) Each composition was applied to a PET film (manufactured by Toray Co., Ltd., product name: Lumirror (registered trademark) S10, thickness: 50 μm) to a cured thickness of 50 μm, and then cured at 150°C for 3 minutes. After leaving it for 1 day, the sample was cut to a width of 20 mm, and the adhesive layer surface was attached to a glass slide (provided by Sinopharm Chemical Reagent Co., Ltd., 25.4 × 76.2 × 2.0 mm) or a polymethyl methacrylate (PMMA) plate (manufactured by Paltec, ACRYLITE L001, 50 × 120 × 2 mm) using a roller to prepare a test specimen, which was then left at room temperature for 30 minutes. For test pieces using glass plates or PMMA plates, adhesive strength (measured over a 20 mm width in gf / inch) was measured at a tensile speed of 300 mm / min using a tensile tester RTC-1210 manufactured by Orientec Co., Ltd., according to the 180-degree peel test method in accordance with JIS Z 0237.

[0099] Comparative Example 1 18.64 parts by weight of component A vinyl-functional polydimethylsiloxane, 4.66 parts by weight of component A' methyl-terminated high molecular weight polydimethylsiloxane; 40.00 parts by weight of component B trimethylsilyl-capped MQ resin, 23.30 parts by weight of component G toluene, 0.4 parts by weight of component C, trimethylsilyl end-blocked poly(dimethylsiloxane-co-methylhydrogen)siloxane; 0.2 parts by weight of component F, 1-ethynyl-1-cyclohexanol Mix thoroughly at room temperature, Then, 0.36 parts by weight of Component E, a platinum-based hydrosilylation reaction catalyst, was added to the mixture to form a curable reactive organopolysiloxane composition. The molar ratio of SiH groups in component (E) to the amount of alkenyl groups in component (A) (SiH / Vi ratio) was 33. After this composition was cured by the above method, the adhesive strength to the glass slide was measured by the same method as above. The evaluation results are shown in Table 2.

[0100] Comparative Example 2 16.31 parts by weight of component A vinyl-functional polydimethylsiloxane, 6.99 parts by weight of component A' methyl-terminated high molecular weight polydimethylsiloxane; 45.00 parts by weight of component B trimethylsilyl-capped MQ resin, 23.30 parts by weight of component G toluene, 0.4 parts by weight of component C, trimethylsilyl end-blocked poly(dimethylsiloxane-co-methylhydrogen)siloxane; 0.2 parts by weight of component F, 1-ethynyl-1-cyclohexanol Mix thoroughly at room temperature, Then, 0.36 parts by weight of Component E, a platinum-based hydrosilylation reaction catalyst, was added to the mixture to form a curable reactive organopolysiloxane composition. The molar ratio of SiH groups in component (E) to the amount of alkenyl groups in component (A) (SiH / Vi ratio) was 37. After this composition was cured by the above method, the adhesive strength to the glass slide was measured by the same method as above. The evaluation results are shown in Table 2.

[0101] Comparative Example 3 13.98 parts by weight of component A vinyl-functional polydimethylsiloxane, 9.32 parts by weight of component A' methyl-terminated high molecular weight polydimethylsiloxane; 45.00 parts by weight of component B trimethylsilyl-capped MQ resin, 23.30 parts by weight of component G toluene, 0.4 parts by weight of component C, trimethylsilyl end-blocked poly(dimethylsiloxane-co-methylhydrogen)siloxane; 0.2 parts by weight of component F, 1-ethynyl-1-cyclohexanol Mix thoroughly at room temperature, Then, 0.36 parts by weight of Component E, a platinum-based hydrosilylation reaction catalyst, was added to the mixture to form a curable reactive organopolysiloxane composition. The molar ratio of SiH groups in component (E) to the amount of alkenyl groups in component (A) (SiH / Vi ratio) was 44. After the composition was cured by the above method, the adhesive strength to the glass slide was measured by the above method. The evaluation results are shown in Table 2.

[0102] Comparative Example 4 11.65 parts by weight of component A vinyl-functional polydimethylsiloxane, 11.65 parts by weight of component A' methyl-terminated high molecular weight polydimethylsiloxane; 45.00 parts by weight of component B trimethylsilyl-capped MQ resin, 23.30 parts by weight of component G toluene, 0.4 parts by weight of component C, trimethylsilyl end-blocked poly(dimethylsiloxane-co-methylhydrogen)siloxane; 0.2 parts by weight of component F, 1-ethynyl-1-cyclohexanol Mix thoroughly at room temperature, Then, 0.36 parts by weight of Component E, a platinum-based hydrosilylation reaction catalyst, was added to the mixture to form a curable reactive organopolysiloxane composition. The molar ratio of SiH groups in component (E) to the amount of alkenyl groups in component (A) (SiH / Vi ratio) was 52. After this composition was cured by the above method, the adhesive strength to the glass slide was measured by the same method as above. The evaluation results are shown in Table 2.

[0103] Comparative Example 5 16.31 parts by weight of component A vinyl-functional polydimethylsiloxane, 6.99 parts by weight of component A' methyl-terminated high molecular weight polydimethylsiloxane; 65.37 parts by weight of Component B trimethylsilyl-capped MQ resin, 23.30 parts by weight of component G toluene, 0.053 parts by weight of component C, trimethylsilyl end-capped poly(dimethylsiloxane-co-methylhydrogen)siloxane; 0.06 parts by weight of component F, 1-ethynyl-1-cyclohexanol Mix thoroughly at room temperature, Then, 0.25 parts by weight of Component E, a platinum-based hydrosilylation reaction catalyst, was added to the mixture to form a curable reactive organopolysiloxane composition. The molar ratio of SiH groups in component (E) to the amount of alkenyl groups in component (A) (SiH / Vi ratio) was 5.0. After this composition was cured by the above method, the adhesive strength to the PMMA plate was measured by the same method as above. The evaluation results are shown in Table 2.

[0104] Example 1 18.64 parts by weight of component A vinyl-functional polydimethylsiloxane, 4.66 parts by weight of component A' methyl-terminated high molecular weight polydimethylsiloxane; 40.00 parts by weight of component B trimethylsilyl-capped MQ resin, 23.30 parts by weight of component G toluene, 0.4 parts by weight of component C, trimethylsilyl end-blocked poly(dimethylsiloxane-co-methylhydrogen)siloxane; 1.0 part by weight of component D, tetraethoxysilane; 0.2 parts by weight of component F, 1-ethynyl-1-cyclohexanol Mix thoroughly at room temperature, Then, 0.36 parts by weight of Component E, a platinum-based hydrosilylation reaction catalyst, was added to the mixture to form a curable reactive organopolysiloxane composition. The molar ratio of SiH groups in component (E) to the amount of alkenyl groups in component (A) (SiH / Vi ratio) was 33. After this composition was cured by the above method, the adhesive strength to the glass slide was measured by the same method as above. The evaluation results are shown in Table 2.

[0105] Example 2 18.64 parts by weight of component A vinyl-functional polydimethylsiloxane, 4.66 parts by weight of component A' methyl-terminated high molecular weight polydimethylsiloxane; 40.00 parts by weight of component B trimethylsilyl-capped MQ resin, 23.30 parts by weight of component G toluene, 0.4 parts by weight of component C, trimethylsilyl end-blocked poly(dimethylsiloxane-co-methylhydrogen)siloxane; 2.0 parts by weight of component D tetraethoxysilane, 0.2 parts by weight of component F, 1-ethynyl-1-cyclohexanol Mix thoroughly at room temperature, Then, 0.36 parts by weight of Component E, a platinum-based hydrosilylation reaction catalyst, was added to the mixture to form a curable reactive organopolysiloxane composition. The molar ratio of SiH groups in component (E) to the amount of alkenyl groups in component (A) (SiH / Vi ratio) was 33. After this composition was cured by the above method, the adhesive strength to the glass slide was measured by the same method as above. The evaluation results are shown in Table 2.

[0106] Example 3 16.31 parts by weight of component A vinyl-functional polydimethylsiloxane, 6.99 parts by weight of component A' methyl-terminated high molecular weight polydimethylsiloxane; 45.00 parts by weight of component B trimethylsilyl-capped MQ resin, 23.30 parts by weight of component G toluene, 0.4 parts by weight of component C, trimethylsilyl end-blocked poly(dimethylsiloxane-co-methylhydrogen)siloxane; 2.0 parts by weight of component D tetraethoxysilane, 0.2 parts by weight of component F, 1-ethynyl-1-cyclohexanol Mix thoroughly at room temperature, Then, 0.36 parts by weight of Component E, a platinum-based hydrosilylation reaction catalyst, was added to the mixture to form a curable reactive organopolysiloxane composition. The molar ratio of SiH groups in component (E) to the amount of alkenyl groups in component (A) (SiH / Vi ratio) was 37. After this composition was cured by the above method, the adhesive strength to the glass slide was measured by the same method as above. The evaluation results are shown in Table 2.

[0107] Example 4 13.98 parts by weight of component A vinyl-functional polydimethylsiloxane, 9.32 parts by weight of component A' methyl-terminated high molecular weight polydimethylsiloxane; 45.00 parts by weight of component B trimethylsilyl-capped MQ resin, 23.30 parts by weight of component G toluene, 0.4 parts by weight of component C, trimethylsilyl end-blocked poly(dimethylsiloxane-co-methylhydrogen)siloxane; 2.0 parts by weight of component D tetraethoxysilane, 0.2 parts by weight of component F, 1-ethynyl-1-cyclohexanol Mix thoroughly at room temperature, Then, 0.36 parts by weight of Component E, a platinum-based hydrosilylation reaction catalyst, was added to the mixture to form a curable reactive organopolysiloxane composition. The molar ratio of SiH groups in component (E) to the amount of alkenyl groups in component (A) (SiH / Vi ratio) was 44. After this composition was cured by the above method, the adhesive strength to the glass slide was measured by the same method as above. The evaluation results are shown in Table 2.

[0108] Example 5 11.65 parts by weight of component A vinyl-functional polydimethylsiloxane, 11.65 parts by weight of component A' methyl-terminated high molecular weight polydimethylsiloxane; 45.00 parts by weight of component B trimethylsilyl-capped MQ resin, 23.30 parts by weight of component G toluene, 0.4 parts by weight of component C, trimethylsilyl end-blocked poly(dimethylsiloxane-co-methylhydrogen)siloxane; 2.0 parts by weight of component D tetraethoxysilane, 0.2 parts by weight of component F, 1-ethynyl-1-cyclohexanol Mix thoroughly at room temperature, Then, 0.36 parts by weight of Component E, a platinum-based hydrosilylation reaction catalyst, was added to the mixture to form a curable reactive organopolysiloxane composition. The molar ratio of SiH groups in component (E) to the amount of alkenyl groups in component (A) (SiH / Vi ratio) was 52. After this composition was cured by the above method, the adhesive strength to the glass slide was measured by the same method as above. The evaluation results are shown in Table 2.

[0109] Reference Example 1 16.31 parts by weight of component A vinyl-functional polydimethylsiloxane, 6.99 parts by weight of component A' methyl-terminated high molecular weight polydimethylsiloxane; 65.37 parts by weight of Component B trimethylsilyl-capped MQ resin, 23.30 parts by weight of component G toluene, 0.34 parts by weight of component C, trimethylsilyl end-blocked poly(dimethylsiloxane-co-methylhydrogen)siloxane; 0.06 parts by weight of component F, 1-ethynyl-1-cyclohexanol Mix thoroughly at room temperature, Then, 0.25 parts by weight of Component E, a platinum-based hydrosilylation reaction catalyst, was added to the mixture to form a curable reactive organopolysiloxane composition. The molar ratio of SiH groups in component (E) to the amount of alkenyl groups in component (A) (SiH / Vi ratio) was 32. After this composition was cured by the above method, the adhesive strength to the PMMA plate was measured by the same method as above. The evaluation results are shown in Table 2.

[0110] Reference Example 2 16.31 parts by weight of component A vinyl-functional polydimethylsiloxane, 6.99 parts by weight of component A' methyl-terminated high molecular weight polydimethylsiloxane; 65.37 parts by weight of Component B trimethylsilyl-capped MQ resin, 23.30 parts by weight of component G toluene, 0.11 parts by weight of component C, trimethylsilyl end-blocked poly(dimethylsiloxane-co-methylhydrogen)siloxane; 0.06 parts by weight of component F, 1-ethynyl-1-cyclohexanol Mix thoroughly at room temperature, Then, 0.25 parts by weight of Component E, a platinum-based hydrosilylation reaction catalyst, was added to the mixture to form a curable reactive organopolysiloxane composition. The molar ratio of SiH groups in component (E) to the amount of alkenyl groups in component (A) (SiH / Vi ratio) was 10. After this composition was cured by the above method, the adhesive strength to the PMMA plate was measured by the same method as above. The evaluation results are shown in Table 2.

[0111] [Table 2] * Adhesion force measured against a PMMA plate.

[0112] As shown in Table 2, the silicone-based PSA layer-forming compositions of Examples 1 to 5, which used tetraethoxysilane (TEOS) as an anchor additive, provided 34 to 65% improvements in adhesion compared to the same compositions without TEOS (=component (C)). Specifically, comparisons of adhesion between Examples 1 and 2 vs. Comparative Example 1 (39% and 65% increases), Example 3 vs. Comparative Example 2 (34% increase), Example 4 vs. Comparative Example 3 (42% increase), and Example 5 vs. Comparative Example 4 (65% increase) show that the use of TEOS resulted in a clear increase and / or improvement in adhesion in the Examples compared to the corresponding Comparative Examples.

[0113] Additionally, the SiH / Vinyl ratios for Examples 1-5 and Comparative Examples 1-4 ranged from 33 to 52. For Reference Examples 1 and 2, the SiH / Vinyl ratios were 32 and 10, respectively. Peel adhesion to PMMA for these two Reference Examples was 2200 gf / in, indicating good cure. However, Comparative Example 5, with a SiH / Vinyl ratio of 5.0, had an adhesion value of 440 gf / in to PMMA, indicating cohesive failure of the PSA, indicating that a SiH / Vinyl ratio >5 is preferred to achieve the technical benefits of the present invention.

Claims

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

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

3. (A1) 50 to 100 mass % of the component (A) has a viscosity of 100,000 mPa s or more at 25°C when measured by the method described in JIS K6249, or a plasticity in the range of 50 to 200, and the alkenyl group is vinyl (CH ２ a crude rubber-like alkenyl group-containing organopolysiloxane having a content of (═CH—) moieties in the range of 0.005 to 0.400 mass %, The component (B) is (B1)R ３ SiO １／２ Units and SiO ４／２ an organopolysiloxane resin or mixture thereof consisting essentially of units, wherein R is a monovalent organic group, and 90 mol % or more of the R are alkyl groups having 1 to 6 carbon atoms or phenyl groups; component (C) is present in an amount such that the molar ratio of the amount of SiH groups in component (C) to the total amount of alkenyl groups in components (A) and (B) is 7 to 100; The silicone-based pressure-sensitive adhesive layer-forming composition according to claim 1, wherein component (E) is a platinum-based catalyst, and is present in an amount such that the content of the platinum-based metal in the solids of the composition, excluding the solvent, is within the range of 0.1 to 200 ppm.

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

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

6. (A1) 50 to 100 mass % of the component (A) has a viscosity of 100,000 mPa s or more at 25°C when measured by the method described in JIS K6249, or a plasticity in the range of 50 to 200, and the alkenyl group is vinyl (CH ２ a crude rubber-like alkenyl group-containing organopolysiloxane having a content of (═CH—) moieties in the range of 0.005 to 0.400 mass %, 50 to 100 mass % of the optional component (A') is (A'1) a crude rubber-like organopolysiloxane having a viscosity at 25°C of 100,000 mPa s or more or a plasticity in the range of 50 to 200 as measured by the method described in JIS K6249; 2. The silicone-based pressure-sensitive adhesive layer-forming composition according to claim 1, wherein the mass ratio of component (A) to component (A') is from 100:0 to 40:

60.

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

8. 2. The silicone-based pressure-sensitive adhesive layer-forming composition according to claim 1, wherein the adhesive strength of a pressure-sensitive adhesive layer having a thickness of 50 μm obtained by curing the composition is more than 20% greater than the adhesive strength of a pressure-sensitive adhesive layer obtained from the same composition but not containing component (D), when measured on a glass substrate at a pull rate of 300 mm / min using a 180-degree peel test method in accordance with JIS Z 0237.

9. 2. The silicone-based pressure-sensitive adhesive layer-forming composition according to claim 1, wherein the adhesive strength of a 50 μm thick pressure-sensitive adhesive layer obtained by curing the composition is in the range of 800 to 3,000 gf / inch when measured at a tension rate of 300 mm / min using a 180-degree peel test method in accordance with JIS Z 0237 on a glass substrate.

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

11. A laminate comprising a pressure-sensitive adhesive layer obtained by curing the silicone-based pressure-sensitive adhesive layer-forming composition described in claim 1 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 more film-like substrates.

13. A film-like substrate; a first release layer formed on the film-like substrate; a pressure-sensitive adhesive layer formed by applying the silicone-based pressure-sensitive adhesive layer-forming composition according to claim 1 onto the release layer and curing the composition; a second release layer laminated to the pressure-sensitive adhesive layer.

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

15. An electronic device or electrical device comprising the elastic adhesive member described in claim 14.