Silicone pressure sensitive adhesive laminates

Abstract

An organic silicone pressure sensitive adhesive (PSA) laminate is provided, comprising: a first release liner, a cured silicone PSA layer formed on the first release liner, and a second release liner on the cured silicone PSA layer; wherein for a PSA having a dynamic storage modulus of less than 1 MPa at -20°C and a thickness of 50 µm, the wet side / tight side peel force between the first release liner and the cured silicone PSA layer (first interface) is less than 100 gf / inch at a peel rate of 0.3 m / min; or for a PSA having a dynamic storage modulus of less than 1 MPa at -20°C, a shear stress of less than 60 kPa at 700% shear strain, and a thickness of 50 µm, the wet side / tight side peel force between the first release liner and the cured silicone PSA layer (first interface) is less than 100 gf / inch at a peel rate of 0.3 m / min. The PSA laminate according to the present invention can exhibit low modulus at small deformation, low stress at large deformation, large creep, etc.

Description

Cross-references to related applications

[0001] none. Technical Field

[0002] The present invention relates to silicone pressure-sensitive adhesive (PSA) laminates, pressure-sensitive adhesive layers for preparing the laminates, and electronic devices or electrical apparatuses comprising the silicone pressure-sensitive adhesive (PSA) laminates. Background Technology

[0003] The use of silicone pressure-sensitive adhesives (PSAs) in assembly applications is growing and is expected to surpass that of masking and protective applications. Assembly applications include optically clear adhesives (OCAs) for displays (automotive displays, foldable displays, etc.), where control over rheological properties is a fundamental requirement in addition to adhesion. Many of these applications, specifically foldable electronics, require low modulus over a wide range of operating temperatures. While existing silicone PSAs exhibit dynamic shear storage modulus (G') of 3 MPa to 20 MPa at -20°C, assembly applications typically require much lower than 1 MPa. The inherently low modulus of silicone, with its good crosslinking elasticity (at low temperatures), is one of the advantages. OCA is coated onto a release liner, cured, and then covered with another release liner to prepare a liner / OCA / liner laminate. In practice, one side of the liner is peeled off to laminate the OCA to a substrate, and then the other side of the liner is peeled off to laminate to another substrate to assemble display panels, etc.

[0004] Patent document 1 describes a Si PSA layer having fine particles with a diameter of 2 μm to 15 μm, which is processable even without the use of a release liner and has no observed adhesion (force less than 1 N / cm). 2 However, the modulus of PSA is not specified, and the haze value is ≥5% in the presence of particles, which makes it unsuitable for use as an OCA.

[0005] Patent Document 2 describes a multilayer Si PSA with a peel force of <195 gf / inch after 46 days at 49°C. However, the peel mechanism is a stretch-peel method, wherein a first pressure-sensitive adhesive layer faces the release liner, and a second pressure-sensitive adhesive layer comprises an elastomer, and the first pressure-sensitive adhesive comprises a silicone polyurethane block copolymer. Patent Document 2's stretch-peel PSA does not mention the peel force from the liner for the specific rheological properties of the PSA, and because the elastomer layer is attached to the PSA layer, this material cannot be used for assembly applications.

[0006] Patent document 3 describes a laminate of a fluoro-organosilicon release liner / Si PSA / fluoro-organosilicon release liner, which has a wide release coating and PSA composition. Release force values ​​of 3 gf / inch to 15 gf / inch on the easy side and 11 gf / inch to 230 gf / inch on the tight side are described, and no OCA damage was observed. However, these are unrelated to any rheological properties of the PSA.

[0007] Related technical documents

[0008] Patent documents

[0009] [Patent Document 1] WO2017010140A1

[0010] [Patent Document 2] WO2008141004A1

[0011] [Patent Document 3] JP2007326312A Summary of the Invention

[0012] Problems to be solved

[0013] As mentioned above, existing technologies do not provide a solution for low-peel force when peeling a "soft" PSA from a release liner, but this is a fundamental requirement for using such PSAs in display assembly. This invention was created to address this problem, with the aim of providing a "soft" PSA (which has low modulus at small deformations, low stress at large deformations, large creep, etc.) as an OCA for display applications, including foldable displays and automotive displays. Silicone PSAs are superior to acrylic PSAs in terms of flexibility, specifically at low temperatures, and good elasticity for restoring function. Another object of this invention is to provide the use of a pressure-sensitive adhesive (PSA) layer as an OCA layer and electronic devices or electrical apparatuses comprising silicone pressure-sensitive adhesive (PSA) laminates.

[0014] Methods for solving problems

[0015] As a result of in-depth research into the problems described above, the inventors have completed this invention. Specifically, one object of the invention is achieved by using a specific hydrosilylation-curable pressure-sensitive adhesive (PSA) organopolysiloxane composition in assembly applications. The PSA film requires die-cutting. An example of the die-cutting process is to peel off the easy side of the pad, kiss-cut (cutting only the PSA, but not the other side of the pad), remove the PSA around the cut shape, and re-laminate the pad to provide a PSA film in the shape of a display between two peel pads having a size larger than the PSA film. In subsequent display assembly, the easy side of the peel pad is peeled off and the PSA is laminated onto a designated substrate, and then the tight side pad is peeled off to laminate with another substrate. In these processes, the peel force needs to be low enough so that (1) the easy pad can be peeled off without damaging the PSA (not the PSA film deformed due to delamination from the tight side during easy side peeling) and (2) the tight side pad can be peeled off without roughening the PSA surface to prevent loss of transparency during assembly. Liner / PSA / liner laminates with sufficiently low peel strength can be used in assembly applications that require flexibility.

[0016] Specifically, the above problems can be solved by using a silicone pressure-sensitive adhesive (PSA) laminate, which includes:

[0017] First peeling liner

[0018] The cured silicone PSA layer formed on the first release liner, and

[0019] The second release liner on the cured silicone PSA layer;

[0020] For a PSA with a dynamic energy storage modulus of less than 1 MPa and a thickness of 50 μm at -20°C, the wet / tight side peel force between the first release liner and the cured silicone PSA layer (first interface) is less than 100 gf / inch at a peel rate of 0.3 m / min.

[0021] In an alternative embodiment according to this disclosure, a silicone pressure-sensitive adhesive (PSA) laminate is provided, the silicone pressure-sensitive adhesive (PSA) laminate comprising:

[0022] First peeling liner

[0023] The cured silicone PSA layer formed on the first release liner, and

[0024] The second release liner on the cured silicone PSA layer;

[0025] For a PSA having a dynamic energy storage modulus of less than 1 MPa at -20°C, a shear stress of less than 60 kPa at 700% shear strain, and a thickness of 50 μm, the wet / tight side peel force between the first release liner and the cured silicone PSA layer (the first interface) is less than 100 gf / inch at a peel rate of 0.3 m / min.

[0026] In embodiments according to this disclosure, the cured silicone PSA layer is obtained by curing a PSA composition comprising:

[0027] (A) Straight-chain organopolysiloxanes with an average of more than one alkenyl group per molecule;

[0028] (B) An organopolysiloxane resin, wherein the total content of silicon atoms, hydroxyl groups and hydrolyzable groups relative to all silicon atoms in the molecule is 9.0 mol% or less;

[0029] (C) an organohydrogen polysiloxane having at least two Si-H bonds in its molecule; and

[0030] (D) Catalyst for hydrosilylation reaction;

[0031] The mass ratio of component (B) to component (A) is in the range of 0.5 to 3.5.

[0032] In an embodiment according to this disclosure, at least a portion of component (A) is (A1) a raw rubber-like organopolysiloxane containing alkenyl groups, 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 according to the method described in JIS K6249, and the content of the vinyl (CH2=CH-) moiety of the alkenyl groups is in the range of 0.005% by mass to 0.400% by mass;

[0033] Component (B) is (B1) basically composed of R 3 SiO 1 / 2 unit and SiO 4 / 2 The unit composition of the organic polysiloxane resin or mixture thereof, wherein 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;

[0034] 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 1 to 100; and

[0035] Component (D) is a platinum-based catalyst and is present in such an amount that, in a solvent-free PSA composition, the content of the platinum-based metal in the solids content of the composition is in the range of 0.1 ppm to 200 ppm.

[0036] In embodiments according to this disclosure, the PSA composition further comprises (A') a linear organopolysiloxane that does not contain carbon-carbon double bond reactive groups in the molecule.

[0037] In an embodiment according to this disclosure, 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 10 to 100 or 20 to 80.

[0038] In an alternative form according to this disclosure, a pressure-sensitive adhesive layer is provided by curing a PSA composition comprising:

[0039] (A) Straight-chain organopolysiloxanes with an average of more than one alkenyl group per molecule;

[0040] (B) An organopolysiloxane resin, wherein the total content of silicon atoms, hydroxyl groups and hydrolyzable groups relative to all silicon atoms in the molecule is 9.0 mol% or less;

[0041] (C) an organohydrogen polysiloxane having at least two Si-H bonds in its molecule; and

[0042] (D) Catalyst for hydrosilylation reaction;

[0043] The mass ratio of component (B) to component (A) is in the range of 0.5 to 3.5.

[0044] In an alternative form according to this disclosure, the use of a pressure-sensitive adhesive (PSA) layer in an assembly application is provided, whereby the assembly application requires a wet / tight side peel force of less than 100 gf / inch at a peel rate of 0.3 m / min for a PSA having a dynamic storage modulus of less than 1 MPa and a thickness of 50 μm at -20°C.

[0045] In embodiments according to this disclosure, PSA is used as an optically transparent adhesive (OCA) for the display.

[0046] In an alternative form according to this disclosure, electronic devices or electrical apparatuses comprising silicone pressure-sensitive adhesive (PSA) laminates are provided.

[0047] Effects of the present invention

[0048] This invention provides a PSA layer with low modulus under small deformation, low stress under large deformation, and high creep, which can be used as an OCA in display applications, including foldable displays and automotive displays. The silicone pressure-sensitive adhesive (PSA) laminate formed from the PSA layer exhibits a wet / tight side peel force of less than 100 gf / inch between the first release liner and the cured silicone PSA layer (the first interface) at a peel rate of 0.3 m / min, for a PSA having a dynamic storage modulus of less than 1 MPa at -20°C, a shear stress of less than 60 kPa at 700% shear strain, and a thickness of 50 μm. Alternatively, for a PSA having a dynamic storage modulus of less than 1 MPa at -20°C, a shear stress of less than 60 kPa at 700% shear strain, and a thickness of 50 μm, the wet / tight side peel force between the first release line and the cured silicone PSA layer (the first interface) is less than 100 gf / inch at a peel rate of 0.3 m / min. Detailed Implementation

[0049] [Silicone Pressure Sensitive Adhesive (PSA) Composition]

[0050] First, the silicone pressure-sensitive adhesive (PSA) composition according to the present invention will be described. This composition is rapidly cured via a curing reaction involving hydrosilylation to form a pressure-sensitive adhesive layer. For a PSA having a dynamic storage modulus of less than 1 MPa and a thickness of 50 μm at -20°C, at a peel rate of 0.3 m / min, the wet-side / tight-side peel force of the pressure-sensitive adhesive layer between the first peel line and the cured silicone PSA layer (the first interface) is less than 100 gf / inch. Hereinafter, the components of 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.

[0051] In an embodiment of the invention, the PSA composition comprises:

[0052] (A) Straight-chain organopolysiloxanes with an average of more than one or two alkenyl groups per molecule;

[0053] (B) An organopolysiloxane resin, wherein the total content of hydroxyl groups and hydrolyzable groups relative to all silicon atoms in the molecule is 9.0 mol% or less, 7.0 mol% or less, 5.0 mol% or less, 3.0 mol% or less, or 1.0 mol% or less;

[0054] (C) an organohydrogen polysiloxane having at least two Si-H bonds in its molecule; and

[0055] (D) Catalyst for hydrosilylation reaction;

[0056] The mass ratio of component (B) to component (A) is in the range of 0.5 to 3.5, 0.8 to 3.0, 0.8 to 2.6, or 0.8 to 2.4. In another embodiment of the invention, the organosilicon PSA composition may further comprise (A') a linear organopolysiloxane that does not contain carbon-carbon double bond reactive groups in its molecule.

[0057] In addition, since the composition contains a hydrogenation silanization reaction catalyst, from a workability point of view, the composition may also contain a curing delay agent (F), and may also contain other additives to a degree that does not contradict the purpose of the present invention.

[0058] [Component (A)]

[0059] In this invention, component (A) is a linear (i.e., chain-like) organopolysiloxane having an average of more than one alkenyl group per molecule, wherein the preferred number of alkenyl groups per molecule is not less than 1.5, and the more preferred number is not less than 2.0. In some embodiments of the invention, the average number of alkenyl groups per molecule can 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 the alkenyl group in component (A) include alkenyl groups having 2 to 10 carbon atoms, such as vinyl groups, allyl groups, butenyl groups, pentenyl groups, hexenyl groups, and heptenyl groups, with vinyl groups or hexenyl groups being particularly preferred. Examples of the bonding positions of the alkenyl group in component (A) include 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.

[0060] Examples of silicon-bonded organic groups in component (A) other than the alkenyl group of the organopolysiloxane include: alkyl groups, such as methyl, ethyl, propyl, butyl, pentyl, hexyl and heptyl groups; aryl groups, such as phenyl, tolyl, xylyl and naphthyl groups; aralkyl groups, such as benzyl and phenethyl groups; and haloalkyl groups, such as chloromethyl, 3-chloropropyl and 3,3,3-trifluoropropyl groups, wherein methyl and phenyl groups are particularly preferred.

[0061] In this invention, component (A) differs from component (B) and has a linear organopolysiloxane molecular structure. For example, component (A) is preferably linear or partially branched linear and may partially comprise a cyclic three-dimensional network. Preferably, the backbone of the organopolysiloxane consists of repeating diorganosiloxane units (i.e., -SiO₂). 2 / 2 It is composed of (or D unit), and preferably is a straight-chain or branched diorganopolysiloxane capped at both ends of the molecule with triorganosiloxy groups. Note that the siloxane unit providing the branched organopolysiloxane is the T unit or Q unit described below.

[0062] The properties of component (A) at room temperature may be those of an oily or raw rubber-like substance, and 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 invention is solvent-based, at least a portion of component (A) is a raw rubber-like organopolysiloxane containing alkenyl groups, with a viscosity of (A1) of not less than 100,000 mPa·s at 25°C or a plasticity value (read at most 1 / 100 mm thickness when a 1 kgf load is applied to a 4.2 g spherical sample at 25°C for 3 minutes and multiplied by 100) in the range of 50 to 200, preferably 80-200, more preferably 100-200, as measured according to the method described in JIS K6249.

[0063] Note that, 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 organopolysiloxane alkenyl group. This degree can be designed as needed, but 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.

[0064] Although the content of alkenyl groups in component (A1) is not specifically limited, the content of the vinyl (CH2=CH) moiety of these alkenyl groups in component (A1) (hereinafter referred to as "vinyl content") may 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 particularly preferably in the range of 0.005% by mass to 0.200% by mass.

[0065] In some embodiments of the invention, a component (A) with a lower viscosity than component (A1) may also be used as component (A) of the invention. Specifically, an organopolysiloxane (A2) containing alkenyl groups with 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).

[0066] In this invention, at least a portion (preferably 50% by mass or more) of component (A) is preferably an organopolysiloxane containing alkenyl groups with a high degree of polymerization, which is component (A1), wherein 75% to 100% by mass is specifically preferably component (A1). That is, when component (A1) (= organopolysiloxane containing alkenyl groups with a high degree of polymerization) and component (A2) (= organopolysiloxane containing alkenyl groups with a low degree of polymerization) are combined as component (A) of this invention, the mass ratio of component (A1) to component (A2) ranges from 50:50 to 100:0, preferably from 75:25 to 100:0, and more preferably from 80:20 to 100:0.

[0067] [Component (B)]

[0068] In this invention, the organopolysiloxane resin of component (B) is an adhesion-imparting component that imparts adhesion to the substrate, and a mixture of organopolysiloxane resins in a constant ratio with component (A) is used to simultaneously achieve a low-temperature energy storage modulus and a practical adhesion range. More specifically, component (B) is an organopolysiloxane resin with a low average molecular weight, wherein the content of hydroxyl groups or hydrolyzable groups is suppressed, and wherein hydrolysis / polymerization reactions between components (B) tend not to occur. The selective use of organopolysiloxane resins with low average molecular weight in the pressure-sensitive adhesive layer, which is its cured product, achieves a predetermined energy storage modulus and practical adhesion range.

[0069] Specifically, component (B) is an organopolysiloxane resin in which the total content of hydroxyl groups and hydrolyzable groups is 9.0 mol% or less, 7.0 mol% or less, 5.0 mol% or less, 3.0 mol% or less, or 1.0 mol% or less, relative to the total number of silicon atoms in the molecule. These hydroxyl groups or hydrolyzable groups are groups directly bonded to silicon atoms of T units or Q units, etc., in the siloxane units of the resin structure described below, and are obtained by hydrolyzing these silanes or silane derivatives. Therefore, the content of hydroxyl groups or hydrolyzable groups can be reduced by synthesizing organopolysiloxane resins through hydrolysis with a silylating agent such as trimethylsilane.

[0070] In component (B), when the amount of hydroxyl groups or hydrolyzable groups exceeds the aforementioned upper limit, condensation reactions occur between these organopolysiloxane resin molecules, thereby promoting the formation of organopolysiloxane resin structures with high molecular weights in the cured product. Such high molecular weight organopolysiloxane resins tend to impair the overall curability of the composition, which may be insufficient at low temperatures, and the resulting pressure-sensitive adhesive layer may not possess a sufficient energy storage modulus for practical use.

[0071] In this invention, component (B) is an organopolysiloxane resin having a three-dimensional structure. Examples of such resins include those made from R₂SiO₃. 2 / 2 Unit (D unit) and RSiO 3 / 2 Resins composed of units (where each R independently represents a monovalent organic group) and having a content of hydroxyl groups or hydrolyzable groups within the above-mentioned range, resins composed solely of T units and having a content of hydroxyl groups or hydrolyzable groups within the above-mentioned range, and resins composed of R3SiO 1 / 2 Unit (M unit) and SiO 4 / 2 A resin composed of units (Q units) and having a content of hydroxyl groups or hydrolyzable groups within the above-mentioned range. Specifically, it is preferable to use a resin composed of R3SiO 1 / 2 Unit (M unit) and SiO 4 / 2 A resin composed of units (Q units) (also known as MQ resin), wherein when all these functional groups are converted into hydroxyl groups, the sum of the contents of hydroxyl groups and hydrolyzable groups is preferably in the range of 0.0% by mass to 1.6% by mass.

[0072] The monovalent organic group of R is preferably a monovalent hydrocarbon group having 1 to 10 carbon atoms, examples of which include alkyl groups having 1 to 10 carbon atoms, alkenyl groups having 2 to 10 carbon atoms, aryl groups having 6 to 10 carbon atoms, cycloalkyl groups having 6 to 10 carbon atoms, benzyl groups, phenethyl groups, and phenylpropyl groups. Specifically, 90 mol% or more of R is preferably an alkyl group or a phenyl group having 1 to 6 carbon atoms, while 95 mol% to 100 mol% of R is specifically preferably a methyl group or a phenyl group.

[0073] Preferably, component (B) is (B1) essentially composed of R3SiO 1 / 2 unit and SiO 4 / 2 The unit composition is an organopolysiloxane resin or a mixture thereof, wherein 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 Unit (M unit) and SiO 4 / 2 When the resin is composed of units (Q units), the molar ratio of M units to Q units is preferably 0.5 to 2.0. This is because when the molar ratio is less than 0.5, the adhesion to the substrate may decrease, while when the molar ratio is greater than 2.0, the cohesive strength of the material constituting the adhesive layer decreases. Furthermore, D units and T units may also be included in component (B) to a degree that does not impair the properties of the invention. Further, to prevent contact failures, etc., low molecular weight siloxane oligomers in these organopolysiloxane resins can be reduced or eliminated.

[0074] In this 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 Mw of component (B), measured by gel permeation chromatography (GPC) according to standard polystyrene, ranges 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).

[0075] [Mass ratio of component (B) to component (A)]

[0076] The pressure-sensitive adhesive organopolysiloxane composition according to the present invention is characterized by having 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. The mass ratio of component (B) to component (A) is in the range of 0.5 to 3.5, 0.8 to 3.0, 0.8 to 2.6, or 0.8 to 2.4. If components (A) and (A') are used in the above-mentioned mass ratio, the technical effects of the present invention can be achieved even if the mass ratio of component (B) to component (A) is greater than the range of 1.8 to 2.4.

[0077] [Component (C)]

[0078] In this invention, component (C) is an organohydrogen polysiloxane having two or more Si-H bonds per molecule, and is a crosslinking agent in the organopolysiloxane composition of this invention. The molecular structure of component (C) is not specifically limited, examples of which include linear, partially branched linear, branched, cyclic, or organopolysiloxane resin structures, with linear, partially branched linear, or organopolysiloxane resin structures being preferred. The bonding positions of the silicon-bonded hydrogen atoms are not specifically limited, examples of which include molecular ends, side chains, or both. The content of 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.

[0079] 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, wherein 50% or more of their total number are preferably alkyl or phenyl groups having 1 to 8 carbon atoms. Other organic groups are preferably methyl or phenyl groups from the perspective of ease of manufacture and compatibility with the preferred components (A) and (B) described above.

[0080] When component (C) of the present invention is an organohydrogen polysiloxane, it is an organopolysiloxane resin, examples of which include organopolysiloxane copolymers composed of the general formula R'3SiO 1 / 2 The siloxane unit represented by the general formula R'2HSiO 1 / 2 The siloxane unit represented by SiO is derived from the formula SiO 4 / 2 The siloxane unit is represented; an organopolysiloxane copolymer composed of the following: [formula omitted for brevity] 1 / 2 The siloxane unit represented by SiO is derived from the formula SiO 4 / 2 The siloxane unit is represented; an organopolysiloxane copolymer composed of the following: [formula omitted for brevity] 1 / 2 The siloxane unit represented by R'SiO 3 / 2 The siloxane unit is represented; an organopolysiloxane copolymer composed of the following: [formula omitted for brevity] 2 / 2 The siloxane unit represented by: (e.g., R'SiO) 3 / 2 The siloxane unit represented by the formula HSiO 3 / 2 The formula represents a siloxane unit; and mixtures of two or more 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, with examples of the same as described above.

[0081] Specific examples of component (C) include tris(dimethylhydrosiloxy)methylsilane, tetra(dimethylhydrosiloxy)silane, methylhydropolysiloxane capped at both ends with trimethylsiloxy groups, dimethylsiloxane / methylhydrosiloxane copolymer capped at both ends with trimethylsiloxy groups, dimethylsiloxane / methylhydrosiloxane copolymer capped at both ends with dimethylhydrosiloxy groups, cyclic methylhydrooligomeric siloxane, cyclic methylhydrosiloxane / dimethylsiloxane copolymer, methylhydrosiloxane / diphenylsiloxane copolymer capped at both ends with trimethylsiloxy groups, methylhydrosiloxane / diphenylsiloxane / dimethylsiloxane copolymer capped at both ends with trimethylsiloxy groups, hydrolytic condensate of trimethylsilane, and (CH3)2HSiO 1 / 2 unit and SiO 4 / 2 A copolymer composed of units, consisting of (CH3)2HSiO 1 / 2 Unit, SiO 4 / 2 Unit and (C6H5)SiO 3 / 2 A copolymer composed of units, consisting of (CH3)2HSiO 1 / 2 Unit and CH3SiO 3 / 2 copolymers composed of units, and mixtures of two or more of them.

[0082] Specifically, in the case of a straight-chain structure, the molecular structural formula is: RTMe2SiO(Me2SiO). q (HMeSiO) r The preferred methylhydrogen polysiloxane is SiMe2RT (where Me is a methyl group, RT is a methyl group or a hydrogen atom, and the subscripts q and r are numbers satisfying 0.3≤r / (q+r)≤1 and 5≤(q+r)≤200). Note that two or more different types of components (C) can be used in combination.

[0083] Similarly, the following organosiloxanes can be given as examples. Note that in these formulas, Me and Ph represent methyl and phenyl groups, 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, with the sum of b, c, d, and e in one molecule being 1.

[0084] HMe2SiO(Ph2SiO) m SiMe2H

[0085] HMePhSiO(Ph2SiO) m SiMePhH

[0086] HMePhSiO(Ph2SiO) m (MePhSiO)n SiMePhH

[0087] HMePhSiO(Ph2SiO) m (Me2SiO) n SiMePhH

[0088] (HMe2SiO 1 / 2 ) b (PhSiO 3 / 2 ) c

[0089] (HMePhSiO 1 / 2 ) b (PhSiO 3 / 2 ) c

[0090] (HMePhSiO 1 / 2 ) b (HMe2SiO 1 / 2 ) c (PhSiO 3 / 2 ) d

[0091] (HMe2SiO 1 / 2 ) b (Ph2SiO2 / 2) c (PhSiO 3 / 2 ) d

[0092] (HMePhSiO 1 / 2 ) b (Ph2SiO2 / 2) c (PhSiO 3 / 2 ) d

[0093] (HMePhSiO 1 / 2 ) b (HMe2SiO 1 / 2 ) c (Ph2SiO2 / 2) d (PhSiO 3 / 2 ) e 。

[0094] [SiH / Vi ratio]

[0095] The composition according to the invention is curable by a hydrosilylation reaction, and the amount of component (C) is not specifically limited, as long as the composition can be fully cured by a hydrosilylation reaction. However, the molar ratio of the amount of hydrogen atoms (SiH) bonded to silicon atoms in component (C) relative to the sum of the amount (mass) of alkenyl groups in component (A) and alkenyl groups in component (B), i.e., the molar ratio, is preferably in the range of 1 to 100, 5 to 80, or 10 to 70; and can be in the range of 15 to 60, 20 to 50, or 30 to 40.

[0096] In contrast, to improve adhesion to substrates such as glass, the number of SiH groups per molecule can be designed to be 10 or more, or 20 or more, preferably more than 20, and more preferably 22 or more. For example, relative to the sum of the amount (mass) of alkenyl groups in component (A) and the amount (mass) of alkenyl groups in component (B) of the composition, the mass of hydrogen atoms (SiH) bonded to silicon atoms in component (C) can be designed to be in the range of 10 to 60 and 10 to 50. When the amount of these SiH groups is below the aforementioned lower limit, the technical effect of improving adhesion to the substrate may not be achieved. In contrast, when the amount of these SiH groups exceeds the aforementioned upper limit, the amount of unreacted residual curing agent becomes large, which may adversely affect the physical properties of the cured product, 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 aforementioned range, a pressure-sensitive adhesive layer sufficient for practical use can be formed.

[0097] [Component (D), catalyst for hydrosilylation reaction]

[0098] The organopolysiloxane compositions of the present invention comprise a hydrogenation silylation reaction catalyst. Examples of hydrogenation silylation reaction catalysts include platinum-based catalysts, rhodium-based catalysts, and palladium-based catalysts, wherein platinum-based catalysts are preferred because they significantly promote the curing of the compositions of the present invention. Examples of platinum-based catalysts include platinum fine powder, chloroplatinic acid, an alcoholic solution of chloroplatinic acid, platinum-alkenylsiloxane complexes, platinum-olefin complexes, and platinum-carbonyl complexes, wherein 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 are substituted with groups selected from the group consisting of: nitriles, amides, dioxolane, sulfolane, ethyl groups, phenyl groups, etc., and alkenylsiloxanes in which the vinyl groups are substituted with allyl groups, hexenyl groups, etc. Specifically, 1,3-divinyl-1,1,3,3-tetramethyldisiloxane is preferred because this platinum-alkenylsiloxane complex exhibits good stability. As the catalyst for promoting this hydrosilylation reaction, non-platinum-based metal catalysts such as iron, ruthenium, iron / cobalt, etc., can be used.

[0099] Although the content of the hydrosilylation catalyst is not specifically limited in this invention, the amount of platinum-based metal relative to the total amount of solids in the composition (i.e., excluding solvent) is in the range of 0.1 ppm to 200 ppm, and may be in the range of 0.1 ppm to 150 ppm, 0.1 ppm to 100 ppm, or 0.1 ppm to 50 ppm. Here, the platinum-based metal is a Group VIII metal element composed of platinum, rhodium, palladium, ruthenium, and iridium; however, in practical use, the content of platinum metal other than the ligand of the hydrosilylation catalyst is preferably within the range described above. Note that the solids content refers to the components that form the cured layer when the organopolysiloxane composition of this invention undergoes a curing reaction (mainly the main reagent, adhesion-improving components, crosslinking agents, catalysts, and other non-volatile components), and does not include volatile components such as solvents that evaporate during thermal curing.

[0100] When the content of the platinum-based metal in the organopolysiloxane composition according to the 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 staining of the transparent pressure-sensitive adhesive layer, specifically after curing or when heated or exposed to high-energy rays such as UV. Meanwhile, 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 below this lower limit, it may lead to curing defects.

[0101] [Component (E)]

[0102] In this invention, component (E) is a curing delay agent (=curing inhibitor), and is formulated to inhibit the crosslinking reaction between the alkenyl groups in the composition and the SiH groups in component (C) to extend the service life at room temperature and improve storage stability. Therefore, in practical use, component (E) can be added to the organopolysiloxane composition for forming a pressure-sensitive adhesive layer according to the present invention.

[0103] Specific examples of component (E) include yne compounds, enyne compounds, organonitrogen compounds, organophosphorus compounds, and oxime compounds. Specific examples include: yne 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.; methylenylcyclosiloxanes, 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.

[0104] From the perspective of the curing behavior of the composition, the organopolysiloxane composition of the present invention for forming a pressure-sensitive adhesive layer is preferably curable at 80°C to 200°C, and the viscosity increases by no more than 1.5 times after 8 hours at room temperature following the preparation of the composition. From the perspective of operability, pot life, and post-curing properties, inhibiting thickening is important, and a large excess of component (C) is contained, wherein even if the content of the platinum-based metal is optionally low, curability can be ensured by curing at a high temperature (80°C to 200°C). Note that such compositions can be achieved by selecting appropriate combinations and mixing amounts of the components described above, the hydrogenation silylation catalyst, and component (E).

[0105] [solvent]

[0106] In addition to the preferred components (A) and (B) described above, the organopolysiloxane composition of the present invention may also contain an organic solvent as a solvent. The type and blending amount of the organic solvent can be adjusted considering factors such as coating workability. Exemplary organic solvents include: aromatic hydrocarbon-based solvents, such as toluene, xylene, and benzene; aliphatic hydrocarbon-based solvents, such as heptane, hexane, octane, and isoparaffins; 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; wherein two or more types can be combined depending on factors such as the wettability of the sheet substrate. The blending amount of the organic solvent is preferably 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).

[0107] [additive]

[0108] The organopolysiloxane compositions of the present invention may optionally contain components other than those described above, without impairing the technical effects of the invention. For example, the composition may contain: adhesion promoters; non-reactive organopolysiloxanes, such as polydimethylsiloxane or polydimethyldiphenylsiloxane; antioxidants, such as phenolic, quinone, amine, phosphorus, phosphite, sulfur, or thioether antioxidants; flame retardants, such as phosphate, halogen, phosphorus, or antimony 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 microparticles (e.g., reinforcing fillers, dielectric fillers, conductive fillers, thermally conductive fillers), etc., may also optionally be blended.

[0109] [(A') Straight-chain organopolysiloxanes that do not contain reactive groups with carbon-carbon double bonds in their molecules]

[0110] The organopolysiloxane compositions according to the present invention may contain non-reactive organopolysiloxanes, such as polydimethylsiloxanes or polydimethyldiphenylsiloxanes, that do not contain reactive groups containing carbon-carbon double bonds, such as alkenyl groups, acryloyl groups, or methacryloyl groups. As a result, the loss coefficient (tan δ), storage modulus (G'), loss modulus (G''), and adhesion of the pressure-sensitive adhesive layer can be improved. For example, polydimethylsiloxanes with hydroxyl groups at the end or polydimethylsiloxanes or polydimethyldiphenylsiloxanes with trimethylsiloxy groups at the end can be used to increase the loss coefficient of the pressure-sensitive adhesive layer, wherein such compositions are included within the scope of the present invention.

[0111] Preferably, component (A') is a raw rubber-like organopolysiloxane with 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 according to the method described in JIS K 6249.

[0112] In a preferred embodiment of the invention, 50% to 100% by mass of component (A) is a raw rubber-like organopolysiloxane containing alkenyl groups, 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 according to the method described in JIS K6249, and the content of the vinyl (CH2=CH-) moiety of the alkenyl groups is in the range of 0.005% to 0.400% by mass; 50% to 100% by mass of optional component (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 according to the method described in JIS K6249; and the mass ratio of component (A) to component (A') in the composition ranges from 100:0 to 40:60.

[0113] [Using an organosilicon PSA composition to form an adhesive layer]

[0114] The method for preparing this organosilicon PSA composition is not specifically limited and is carried out by uniformly mixing the respective components. Solvents may be added as needed, and the composition can be prepared by mixing at temperatures from 0°C to 200°C using a known stirrer or kneader.

[0115] The aforementioned organosilicon PSA composition forms a cured adhesive layer when applied to a substrate, and is further cured by heating at a temperature of 80°C to 200°C, preferably 90°C to 190°C. Examples of application methods include gravure coating, offset coating, offset gravure, roller coating, reverse roller coating, air knife coating, curtain coating, and comma coating.

[0116] The cured adhesive layer from the said silicone PSA composition is arranged between the functional layers to bond / assemble the layers in the electronic article of the present invention.

[0117] [Silicone Pressure-Sensitive Adhesive (PSA) Laminate]

[0118] In embodiments of this disclosure, the pressure-sensitive adhesive layer is obtained by curing a PSA composition. In embodiments of this disclosure, the pressure-sensitive adhesive layer is used for assembly applications where, for a PSA having a dynamic storage modulus of less than 1 MPa and a thickness of 50 μm at -20°C, the assembly application requires a wet-side / tight-side peel force of less than 100 gf / inch at a peel rate of 0.3 m / min. In embodiments of this disclosure, the PSA is used as an optically clear adhesive (OCA) for displays.

[0119] In embodiments of this disclosure, a silicone pressure-sensitive adhesive (PSA) laminate is provided, the silicone pressure-sensitive adhesive (PSA) laminate comprising:

[0120] First peeling liner

[0121] The cured silicone PSA layer formed on the first release liner, and

[0122] The second release liner on the cured silicone PSA layer;

[0123] For a PSA with a dynamic energy storage modulus of less than 1 MPa and a thickness of 50 μm at -20°C, at a peel rate of 0.3 m / min, the wet / tight side peel force between the first release liner and the cured silicone PSA layer (the first interface) is less than 100 gf / inch, less than 90 gf / inch, less than 80 gf / inch, less than 70 gf / inch, less than 60 gf / inch, or less than 50 gf / inch.

[0124] In embodiments of this disclosure, a silicone pressure-sensitive adhesive (PSA) laminate is provided, the silicone pressure-sensitive adhesive (PSA) laminate comprising:

[0125] First peeling liner

[0126] The cured silicone PSA layer formed on the first release liner, and

[0127] The second release liner on the cured silicone PSA layer;

[0128] For a PSA having a dynamic energy storage modulus of less than 1 MPa at -20°C, a shear stress of less than 60 kPa at 700% shear strain, and a thickness of 50 μm, at a peel rate of 0.3 m / min, the wet / tight side peel force between the first release liner and the cured silicone PSA layer (the first interface) is less than 100 gf / inch, less than 90 gf / inch, less than 80 gf / inch, less than 70 gf / inch, less than 60 gf / inch, or less than 50 gf / inch.

[0129] In embodiments of this disclosure, an electronic device or electrical apparatus comprising a silicone pressure-sensitive adhesive (PSA) laminate is also provided.

[0130] [Wet side / Tight side peel force]

[0131] Wet / tight side peel force can be measured by coating a PSA onto a wet / tight side release liner, curing the PSA, laminating a PET film onto the PSA, and then peeling off the wet / tight side liner to measure the peel force. This can be done by keeping the PET film vertical by laminating it onto a rigid substrate (e.g., a plastic sheet) and pulling the release liner upwards at a 180° angle at a fixed speed (e.g., 0.3 m / min). In a roll coating process, a dry / easy side liner is laminated onto the cured PSA. In this case, the dry / easy side release liner is peeled off, and the PSA on the wet / tight side release liner is laminated onto the PET film, followed by measuring the peel force in the same manner as described above.

[0132] [Method for applying PSA composition]

[0133] As for the coating method applied to the substrate, there can be no limitation to gravure coating, offset coating, offset gravure, roller coating using an offset transfer roller coating machine, reverse roller coating, air knife coating, curtain coating using a curtain flow coating machine, comma coating, Meyer bar, or another known method for the purpose of forming a cured layer.

[0134] The coating amount can be designed to the desired thickness depending on the application, such as a display device. As an example, the thickness of the pressure-sensitive adhesive layer after curing can be 1µm to 1000µm, 5µm to 900µm, or 10µm to 800µm; however, it is not limited to this.

[0135] Depending on the required properties, the pressure-sensitive adhesive layer according to the invention can be a single layer or a multilayer structure obtained by laminating two or more pressure-sensitive adhesive layers. A multilayer pressure-sensitive adhesive layer can be formed by bonding a pressure-sensitive adhesive film (which is formed film-by-film) to it, or by repeatedly applying and curing the organopolysiloxane composition forming the pressure-sensitive adhesive layer onto a film substrate (including a release layer), etc.

[0136] In addition to its adhesive or bonding 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 dissipation layers, insulating layers, reinforcing layers, etc. Furthermore, as an interlayer silicone-based PSA layer, in addition to its adhesive or bonding function between components, the silicone-based PSA layer of the present invention can be applied as a damping / vibration-damping layer.

[0137] Preferably, since the interlayer adhesive layer has both assembly / adhesion layer and damping / vibration damping layer functions, electronic products based on the silicone PSA layer of the present invention do not require an additional interlayer damping / vibration damping layer between the two functional layers. Due to this dual-functionality of the interlayer adhesive layer, the present invention allows the electronic product to be constructed without using any other interlayer damping / vibration damping layer between the two functional layers besides the interlayer adhesive layer according to the present invention.

[0138] In a preferred embodiment, the electronic product having the silicone-based PSA layer of the present invention as its interlayer adhesive layer is an LED or OLED type display device and its modules, having a structure in which transparent display units are directly bonded or assembled to other functional units using the interlayer adhesive layer, wherein 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 with essentially no additional interlayer damping / vibration-damping layers besides the interlayer adhesive layer of the present invention (i.e., eliminating thick and multi-layered damping / vibration-damping layers from these devices), the overall thickness of the display can be thinner and lighter compared to conventional devices.

[0139] When the cured layer obtained by curing the organopolysiloxane composition of the present invention is a pressure-sensitive adhesive layer, specifically a pressure-sensitive adhesive layer, it is preferably treated as a laminate that can be peelably adhered to a membrane substrate provided with a release layer having peel coating capability. This release layer may also be referred to as a release liner, diaphragm, release layer, or release coating, and can preferably be a release layer with peel coating capability, such as a silicone-based release agent, a fluorine-based release agent, an alkyd-based release agent, or a fluorosilicone-based release agent. Alternatively, the release layer can be formed by creating physically fine irregularities on the surface of the substrate, making it difficult to adhere to the resin sheet of the present invention for the pressure-sensitive adhesive layer. 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.

[0140] The cured product obtained by curing the organopolysiloxane composition according to the invention possesses both viscoelasticity and adhesive strength as described above, making it suitable for use as an elastic adhesive component in various types of electronic devices or electrical installations. Specifically, it is useful as electronic materials, components for display devices, and components for transducers (including sensors, speakers, actuators, and generators), with suitable applications for the cured product being electronic parts or components for display devices. The cured product according to the invention can be transparent or opaque, wherein, specifically, film-like cured products, particularly substantially transparent pressure-sensitive adhesive films, are suitable as components for display panels or displays, and in which the device can be operated by touching the screen with fingertips, etc., particularly useful in so-called touch panel applications of electronic devices. Furthermore, opaque elastic adhesive layers do not need to be transparent, making them particularly suitable for applications involving film or sheet-like components used in sensors, speakers, actuators, etc., where the adhesive layer itself requires constant elasticity or flexibility.

[0141] 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 conventional silicone pressure-sensitive adhesive layers, and can improve adhesion to substrates such as display devices without causing problems of poor curing or reduced curing properties.

[0142] Example

[0143] These embodiments are intended to illustrate the invention to those skilled in the art and are not to be construed as limiting the scope of the invention as set forth in the claims. Note that in each of the embodiments, comparative embodiments, and reference embodiments, "curing" means that the compositions are fully cured under the respective curing conditions.

[0144] [Preparation of Curable Organopolysiloxane Compositions]

[0145] The curable organopolysiloxane compositions described in each example and comparative example were prepared using the components shown in Table 1.

[0146]

[0147] [Preparation of silicone pressure-sensitive adhesive (PSA) laminates]

[0148] Silicone pressure-sensitive adhesive (PSA) laminates were prepared using the pads listed in Table 2 for the examples (IE1 to 9), comparative examples (CE1 to 7), and reference examples (RE1 to 2).

[0149]

[0150] [Measurement of molecular weight of organopolysiloxane components]

[0151] Using gel permeation chromatography (GPC) available from Waters, equipped with two continuously connected Tosoh TSKgel Multipore H... XL -M column, toluene is used as solvent, and the weight-average molecular weight (Mw) and number-average molecular weight (Mn) of organopolysiloxane components such as organopolysiloxane resins are determined relative to standard polystyrene.

[0152] [Measurement of the content of hydroxyl groups (OH) in organopolysiloxane resins]

[0153] Use Bruker ACP-300 equipped with a glassless probe. 29 Si NMR spectrometer. By setting the chemical shift of tetramethylsilane to 0 ppm, Si(OH)O appearing in the range of -93 ppm to -103.5 ppm was determined. 2 / 3 The molar content of the unit relative to all silicon atoms. Note that in the following examples, the organopolysiloxane resin does not contain any hydrolyzable groups other than hydroxyl groups.

[0154] [Plasticizer]

[0155] Plasticity was measured according to the method described in JIS K 6249 by measuring the thickness of a 4.2 g spherical sample at 25 °C under a 1 kgf load for 3 minutes with an accuracy of 1 / 100 mm and multiplying by 100.

[0156] [Peel force measurement]

[0157] The organopolysiloxane composition was coated onto the release liner described in Table 2, cured to a thickness of 50 μm, and then cured in an oven at 150°C for 3 min. Another liner was laminated onto the cured organopolysiloxane composition. The side of the release liner coated with the organopolysiloxane composition before curing is designated as the "wet side," and the side of the release liner laminated onto the cured organopolysiloxane composition is designated as the "dry side." The 50 μm thick organopolysiloxane film between the two release liner films was cut into 20 mm wide strips. The wet-side liner film was adhered to a 5 mm thick plastic sheet using double-sided tape. Using an Orientec RTC-1210 tensile testing machine equipped with a 1 kgf load sensor, the plastic sheet, together with a wet-side gasket coated with organopolysiloxane, was vertically fixed to the lower part of the tensile testing machine fixture. The dry-side gasket film was peeled vertically upwards at a crosshead speed of 0.3 m / min at 23°C / 50%RH to measure the dry-side peel force. The organopolysiloxane layer on the wet-side gasket was then laminated onto a 50 μm thick PET film. The PET film was then adhered to the plastic sheet in the same manner, and the wet-side gasket was peeled off in the same way. The obtained values, expressed as gf / 20 mm, were converted to gf / inch.

[0158] [Viscoelasticity: Shear storage modulus and stress]

[0159] Each organopolysiloxane composition was applied to a release liner to a cured thickness of approximately 100 μm, and then cured at 150 °C for 5 minutes. Five or more cured organopolysiloxane composition films were laminated to obtain a film sample with a thickness of 500 μm or more, with both surfaces sandwiched between the release liner. In another case, the organopolysiloxane composition was applied to a release liner with a cured thickness of approximately 280 μm, and then cured at 150 °C for 15 minutes. In this case, two cured films were laminated to obtain a film sample with a thickness of 500 μm or more, with both surfaces sandwiched between the release liner. The film was cut into circles with a diameter of 8 mm and subjected to dynamic mechanical analysis using a parallel plate measurement system on an Anton Paar MCR301 rheometer. Measurements were taken at a frequency of 1 Hz and a temperature gradient of 3 °C / min, ranging from -70 °C to 200 °C, to provide the energy storage elastic modulus G', loss modulus G'', and tan δ, from which the value of G' at -20 °C was obtained.

[0160] For a similar membrane sample with a thickness of 300 μm, the shear stress-strain curve was obtained using the same instrument at a strain rate of 2 / min, and the stress value at 700% strain was recorded.

[0161] Example 1

[0162] 35.1 parts by weight of vinyl-functionalized polydimethylsiloxane adhesive A, 89.5 parts by weight of MQ silicone resin B-2, 42.1 parts by weight of toluene, 0.662 parts by weight of dimethylsiloxane / methylhydrosiloxane copolymer C with trimethylsiloxy groups at both ends, and 0.115 parts by weight of curing inhibitor E were thoroughly mixed at room temperature. Then, 0.355 parts by weight of platinum-based hydrosilylation catalyst D was added to the mixture and thoroughly mixed to form a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of SiH groups in component C to alkenyl groups in component A was 28.7, and the platinum metal content relative to the solids content was 22 ppm.

[0163] The composition was coated onto pad II-B and cured by the method described above. Peel strength and viscoelasticity were measured by the method described above, and the evaluation results are shown in Table 3.

[0164] Example 2

[0165] 29.7 parts by weight of vinyl-functionalized polydimethylsiloxane adhesive A, 7.43 parts by weight of non-functionalized polydimethylsiloxane adhesive A', 86.7 parts by weight of MQ silicone resin B-2, 42.8 parts by weight of toluene, 0.584 parts by weight of dimethylsiloxane / methylhydrosiloxane copolymer C with trimethylsiloxy groups at both ends, and 0.082 parts by weight of curing inhibitor E were thoroughly mixed at room temperature. Then, 0.355 parts by weight of platinum-based hydrosilylation catalyst D was added to the mixture and thoroughly mixed to form a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of SiH groups in component C to alkenyl groups in component A was 29.9, and the platinum metal content relative to the solids content was 22 ppm.

[0166] The composition was coated onto pad II-B and cured by the method described above. Peel strength and viscoelasticity were measured by the method described above, and the evaluation results are shown in Table 3.

[0167] Example 3

[0168] 18.6 parts by weight of vinyl-functionalized polydimethylsiloxane adhesive A, 18.6 parts by weight of non-functionalized polydimethylsiloxane adhesive A', 86.7 parts by weight of MQ silicone resin B-2, 42.8 parts by weight of toluene, 0.423 parts by weight of dimethylsiloxane / methylhydrosiloxane copolymer C with trimethylsiloxy groups at both ends, and 0.082 parts by weight of curing inhibitor E were thoroughly mixed at room temperature. Then, 0.355 parts by weight of platinum-based hydrosilylation catalyst D was added to the mixture and thoroughly mixed to form a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of SiH groups in component C to alkenyl groups in component A was 34.5, and the platinum metal content relative to the solids content was 22 ppm.

[0169] The composition was coated onto pad II-A and cured by the method described above, and the peel strength and viscoelasticity were measured by the method described above, with the evaluation results shown in Table 3.

[0170] Example 4

[0171] The same composition as in Example 3 was applied to pad II-B and cured via the method described above for peel force measurement, with the evaluation results shown in Table 3.

[0172] Example 5

[0173] The same composition as in Example 3 was applied to pad II-C and cured via the method described above for peel force measurement, with the evaluation results shown in Table 3.

[0174] Example 6

[0175] 24.5 parts by weight of vinyl-functionalized polydimethylsiloxane adhesive A, 10.5 parts by weight of non-functionalized polydimethylsiloxane adhesive A', 89.7 parts by weight of MQ silicone resin B-2, 42.0 parts by weight of toluene, 0.508 parts by weight of dimethylsiloxane / methylhydrosiloxane copolymer C with trimethylsiloxy groups at both ends, and 0.082 parts by weight of curing inhibitor E were thoroughly mixed at room temperature. Then, 0.355 parts by weight of platinum-based hydrosilylation catalyst D was added to the mixture and thoroughly mixed to form a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of SiH groups in component C to alkenyl groups in component A was 31.5, and the platinum metal content relative to the solids content was 22 ppm.

[0176] The composition was coated onto pad II-B and cured by the method described above. Peel strength and viscoelasticity were measured by the method described above, and the evaluation results are shown in Table 3.

[0177] Example 7

[0178] 21.0 parts by weight of vinyl-functionalized polydimethylsiloxane adhesive A, 14.0 parts by weight of non-functionalized polydimethylsiloxane adhesive A', 89.7 parts by weight of MQ silicone resin B-2, 42.0 parts by weight of toluene, 0.457 parts by weight of dimethylsiloxane / methylhydrosiloxane copolymer C with trimethylsiloxy groups at both ends, and 0.082 parts by weight of curing inhibitor E were thoroughly mixed at room temperature. Then, 0.355 parts by weight of platinum-based hydrosilylation catalyst D was added to the mixture and thoroughly mixed to form a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of SiH groups in component C to alkenyl groups in component A was 33.1, and the platinum metal content relative to the solids content was 22 ppm.

[0179] The composition was coated onto pad II-B and cured by the method described above. Peel strength and viscoelasticity were measured by the method described above, and the evaluation results are shown in Table 3.

[0180] Example 8

[0181] 17.5 parts by weight of vinyl-functionalized polydimethylsiloxane adhesive A, 17.5 parts by weight of non-functionalized polydimethylsiloxane adhesive A', 89.7 parts by weight of MQ silicone resin B-2, 42.0 parts by weight of toluene, 0.407 parts by weight of dimethylsiloxane / methylhydrosiloxane copolymer C with trimethylsiloxy groups at both ends, and 0.082 parts by weight of curing inhibitor E were thoroughly mixed at room temperature. Then, 0.355 parts by weight of platinum-based hydrosilylation catalyst D was added to the mixture and thoroughly mixed to form a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of SiH groups in component C to alkenyl groups in component A was 35.4, and the platinum metal content relative to the solids content was 22 ppm.

[0182] The composition was coated onto pad II-B and cured by the method described above. Peel strength and viscoelasticity were measured by the method described above, and the evaluation results are shown in Table 3.

[0183] Example 9

[0184] 22.3 parts by weight of vinyl-functionalized polydimethylsiloxane adhesive, 14.9 parts by weight of non-functionalized polydimethylsiloxane adhesive A', 86.7 parts by weight of MQ silicone resin B-2, 42.8 parts by weight of toluene, 0.476 parts by weight of dimethylsiloxane / methylhydrosiloxane copolymer C with trimethylsiloxy groups at both ends, and 0.082 parts by weight of curing inhibitor E were thoroughly mixed at room temperature. Then, 0.355 parts by weight of platinum-based hydrosilylation catalyst D was added to the mixture and thoroughly mixed to form a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of SiH groups in component C to alkenyl groups in component A was 32.4, and the platinum metal content relative to the solids content was 22 ppm.

[0185] The composition was coated onto pad II-B and cured by the method described above. Peel strength and viscoelasticity were measured by the method described above, and the evaluation results are shown in Table 3.

[0186] Comparative Example 1

[0187] The same composition as in Example 1 was applied to pad I and cured via the method described above for peel force measurement, with the evaluation results shown in Table 3.

[0188] Comparative Example 2

[0189] The same composition as in Example 2 was applied to pad I and cured via the method described above for peel force measurement, with the evaluation results shown in Table 3.

[0190] Comparative Example 3

[0191] The same composition as in Example 3 was applied to pad I and cured via the method described above for peel force measurement, with the evaluation results shown in Table 3.

[0192] Comparative Example 4

[0193] The same composition as in Example 6 was applied to pad I and cured via the method described above for peel force measurement, with the evaluation results shown in Table 3.

[0194] Comparative Example 5

[0195] The same composition as in Example 7 was applied to pad I and cured via the method described above for peel force measurement, with the evaluation results shown in Table 3.

[0196] Comparative Example 6

[0197] The same composition as in Example 8 was applied to pad I and cured via the method described above for peel force measurement, with the evaluation results shown in Table 3.

[0198] Comparative Example 7

[0199] The same composition as in Example 9 was applied to pad I and cured via the method described above for peel force measurement, with the evaluation results shown in Table 3.

[0200] Refer to Example 1

[0201] 30.7 parts by weight of vinyl-functionalized polydimethylsiloxane adhesive A, 15.1 parts by weight of MQ silicone resin B-1, 82.2 parts by weight of MQ silicone resin B-2, 38.7 parts by weight of toluene, 0.598 parts by weight of dimethylsiloxane / methylhydrosiloxane copolymer C with trimethylsiloxy groups at both ends, and 0.115 parts by weight of curing inhibitor E were thoroughly mixed at room temperature. Then, 0.355 parts by weight of platinum-based hydrosilylation catalyst D was added to the mixture and thoroughly mixed to form a curable organopolysiloxane composition. The molar ratio (SiH / Vi ratio) of SiH groups in component C to alkenyl groups in component A was 29.6, and the platinum metal content relative to the solids content was 22 ppm.

[0202] The composition was coated onto pad II-B and cured by the method described above. Peel strength and viscoelasticity were measured by the method described above, and the evaluation results are shown in Table 3.

[0203] Refer to Example 2

[0204] The same composition as in Reference Example 1 was applied to pad I and cured by the method described above for peel force measurement. The evaluation results are shown in Table 3.

[0205]

[0206] The formulations listed in Table 3 were coated onto a fluoro-silicone release liner and cured in an oven at 150°C for 3 min to prepare a PSA film with a thickness of 50 μm ± 5 μm. For a 100 μm thick PSA film, the curing time at 150°C was 5 min, and for a 280 μm thick PSA film, the curing time was 15 min. The 100 μm thick PSA film (IE1 and RE1) was laminated more than 5 times to prepare a PSA film >0.5 mm thick for DMA temperature profiling, and laminated 3 times to prepare a 300 μm thick film for shear strain measurement. The 280 μm thick film (IE2-10) was laminated twice or used as is.

[0207] Characteristic Measurement

[0208] The peel force of a 50 μm thick PSA film between two 20 mm wide peel pads was measured using a tensile testing instrument. First, the tight / wet side pads were adhered to a plastic sheet, vertically fixed to the instrument, and the easy / dry side pads were peeled at a 180° angle at a peel rate of 0.3 m / min to measure the easy side peel force. The tight side peel force (d) was measured in the same manner after the PSA laminated onto the tight side pads was applied to a PET film and the PET film was adhered to the plastic sheet. The force values ​​were converted to gf / inch. For PSA films >0.5 mm thick, dynamic mechanical analysis (DMA) was performed in parallel plate mode (8 mm diameter), with a temperature scan from -70 °C to 200 °C at a frequency of 1 Hz. Shear stress-strain curves were obtained using a 300 μm thick film sample and the same instrument at a shear rate of 200% / min at -20 °C.

[0209] As shown in Table 3, Examples 1 to 9 provided wet (tight) side peel forces below 30 gf / inch, while in Comparative Examples 1 to 7, this value exceeded 200 gf / inch or was unmeasurable due to intense rapid movement. In Examples 1 to 9, after peeling the dry side and laminating it onto the PET film, the dry (easy) side pad could be peeled off without damaging the PSA, and the wet side pad could be peeled off without roughening the PSA surface. Therefore, Examples 1 to 9 provide pad / PSA / pad laminates that can withstand the display assembly process.

[0210] The difference between the PSAs in Examples 2 to 9 and the PSA in Example 1 lies in the shear stress at 700% strain, which is less than 60 kPa, while the shear stress of the PSA in Example 1 shows a value of 69 kPa. Due to their softness or ease of deformation in this manner, these PSAs exhibit heavier peel strength, as shown in the dry-side peel strength of Comparative Examples 2 to 7, which unexpectedly shows a considerably lower peel strength compared to those in Examples 2 to 9. Therefore, the laminates shown in Examples 1 to 9 enable the industrial and practical use of these low-modulus OCAs currently required in the display market.

[0211] As shown in Examples 1 and 2, for PSAs with G' greater than 1 MPa at -20°C, the peel force is at a reasonably low level regardless of the type of peeling liner used.

Claims

1. A silicone pressure-sensitive adhesive (PSA) laminate, said silicone pressure-sensitive adhesive (PSA) laminate comprising: First peeling liner The cured silicone PSA layer formed on the first release liner, and A second release liner on the cured silicone PSA layer; For a PSA with a dynamic energy storage modulus of less than 1 MPa and a thickness of 50 μm at -20°C, the wet / tight side peel force between the first release liner and the cured silicone PSA layer is less than 100 gf / inch at a peel rate of 0.3 m / min.

2. A silicone pressure-sensitive adhesive (PSA) laminate, said silicone pressure-sensitive adhesive (PSA) laminate comprising: First peeling liner The cured silicone PSA layer formed on the first release liner, and A second release liner on the cured silicone PSA layer; For a PSA having a dynamic energy storage modulus of less than 1 MPa at -20°C, a shear stress of less than 60 kPa at 700% shear strain, and a thickness of 50 μm, the wet-side / tight-side peel force between the first release liner and the cured silicone PSA layer (first interface) is less than 100 gf / inch at a peel rate of 0.3 m / min.

3. The silicone pressure-sensitive adhesive (PSA) laminate according to claim 1 or 2, wherein the cured silicone PSA layer is obtained by curing a PSA composition, the PSA composition comprising: (A) Straight-chain organopolysiloxanes with an average of more than one alkenyl group per molecule; (B) An organopolysiloxane resin, wherein the total content of hydroxyl groups and hydrolyzable groups relative to all silicon atoms in the molecule is 9.0 mol% or less; (C) an organohydrogen polysiloxane having at least two Si-H bonds in its molecule; and (D) Catalyst for hydrosilylation reaction; The mass ratio of component (B) to component (A) is in the range of 0.5 to 3.

5.

4. The silicone pressure-sensitive adhesive (PSA) laminate according to claim 3, wherein at least a portion of component (A) is a raw rubber-like organopolysiloxane containing alkenyl groups, 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 according to 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; Component (B) is (B1) basically composed of R 3 SiO 1 / 2 unit and SiO 4 / 2 The unit composition of the organic polysiloxane resin or mixture thereof, wherein 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; 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 1 to 100; and Component (D) is a platinum-based catalyst and is present in such an amount that, in the PSA composition without solvent, the content of the platinum-based metal in the solids content of the composition is in the range of 0.1 ppm to 200 ppm.

5. The silicone pressure-sensitive adhesive (PSA) laminate according to claim 3, wherein the PSA composition further comprises (A') a linear organopolysiloxane that does not contain carbon-carbon double bond reactive groups in the molecule.

6. The silicone pressure-sensitive adhesive (PSA) laminate according to claim 3, wherein 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 10 to 100.

7. The silicone pressure-sensitive adhesive (PSA) laminate according to claim 3, wherein 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 20 to 80.

8. A pressure-sensitive adhesive layer, said pressure-sensitive adhesive layer being obtained by curing a PSA composition, said PSA composition comprising: (A) Straight-chain organopolysiloxanes with an average of more than one alkenyl group per molecule; (B) An organopolysiloxane resin, wherein the total content of hydroxyl groups and hydrolyzable groups relative to all silicon atoms in the molecule is 9.0 mol% or less; (C) an organohydrogen polysiloxane having at least two Si-H bonds in its molecule; and (D) Catalyst for hydrosilylation reaction; The mass ratio of component (B) to component (A) is in the range of 0.5 to 3.

5.

9. The use of the pressure-sensitive adhesive (PSA) layer according to claim 8 in an assembly application, wherein the assembly application requires a wet / tight side peel force of less than 100 gf / inch at a peel rate of 0.3 m / min for a PSA having a dynamic storage modulus of less than 1 MPa and a thickness of 50 μm at -20°C.

10. The use according to claim 9, wherein the PSA is used as an optically transparent adhesive (OCA) for the display.

11. An electronic device or electrical apparatus comprising a silicone pressure-sensitive adhesive (PSA) laminate according to any one of claims 1 to 7.

Images