Curable organopolysiloxane composition, slightly-adhesive organopolysiloxane adhesive agent layer obtained by curing same, and laminate

Abstract

[Problem] To provide: an organopolysiloxane composition which can undergo a curing reaction, which forms a slightly-adhesive adhesive agent layer having excellent transparency, and from which it is possible to design a heat-curable / light-curable composition that can be applied even if the contained amount of a solvent is less; a cured product of same; and use of same. [Solution] A curable organopolysiloxane composition comprising: (A) a chain-like organopolysiloxane having an alkenyl group; (B) at least one radically reactive component selected from (B1) vinyl-based monomers and (B2) (meth)acrylic group-containing organopolysiloxane compounds; and (C) a radical polymerization initiator, wherein the sum of component (A) and component (B2) is 50 mass% or more with respect to the total mass of solid content in the composition.

Description

Curable organopolysiloxane composition, and weakly adhesive organopolysiloxane pressure-sensitive adhesive layer and laminate obtained by curing the same

[0001] The present invention relates to a curable organopolysiloxane composition that can be made solvent-free or low-solvent as needed and that undergoes a radical polymerization curing reaction upon heating or high-energy radiation irradiation to form an organopolysiloxane pressure-sensitive adhesive layer that is highly transparent and has low adhesiveness, a laminate having the organopolysiloxane pressure-sensitive adhesive layer, and a method for producing the same. In the present invention, the pressure-sensitive adhesive includes so-called pressure-sensitive adhesives (PSA).

[0002] Curable silicone compositions capable of forming pressure-sensitive adhesive layers upon curing are used in a wide range of industrial fields because they form pressure-sensitive adhesive layers that have excellent heat resistance, cold resistance, electrical insulation, weather resistance, water repellency, and transparency compared to acrylic or rubber-based pressure-sensitive adhesives or pressure-sensitive adhesive compositions. In particular, silicone-based pressure-sensitive adhesive layers after curing have excellent heat resistance compared to other organic materials, are less likely to discolor even at high temperatures, and experience little deterioration in physical properties, making them suitable for use as adhesives, sealants, or temporary fixing agents between components in manufacturing processes for optical materials, semiconductor devices, and the like that include high-temperature retention processes.

[0003] In particular, in recent years, taking advantage of the above-mentioned properties of silicone-based pressure-sensitive adhesive layers and their ability to achieve high transparency as needed, applications to advanced electronics materials such as smart devices and the field of display elements have been considered. 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 it is expected that a silicone-based pressure-sensitive adhesive layer with excellent heat and cold resistance will function effectively in the article and in its manufacturing process, with the aim of protecting the electrode layer and the display layer and improving the adhesion between the layers.

[0004] These silicone-based pressure-sensitive adhesive cured products are classified into addition reaction curing types, condensation reaction curing types, peroxide curing types, etc., depending on their curing mechanism. Addition reaction curing silicone-based pressure-sensitive adhesive compositions are widely used because they cure quickly when left at room temperature or when heated, are less likely to cause cloudiness in the pressure-sensitive adhesive layer, have excellent transparency, and do not produce by-products. However, from the standpoint of coatability and handling, they are generally commercialized by dissolving them in organic solvents, which limits their applications. In particular, in recent years, due to the direction of environmental regulations around the world, there has been a strong demand for the development of solvent-free or low-solvent compositions. In addition, with the recent trend toward lower energy consumption in manufacturing processes, there are an increasing number of situations in which photocurable materials that cure upon irradiation with high-energy rays such as ultraviolet light, which do not require high temperatures, are required in the process. In addition, in recent years, in manufacturing processes such as semiconductors, there has been a demand for easily peelable, slightly adhesive layers, such as for temporary fixing of components or protective films.

[0005] Patent Document 1 (particularly Preparation Example 1, etc.) discloses a solvent-free silicone pressure-sensitive adhesive composition containing an acrylic group-containing dimethylpolysiloxane, an MQ-type dimethylpolysiloxane resin, and a photopolymerization initiator, and a dicing tape using the same. Similarly, Patent Document 2 discloses a solvent-free silicone pressure-sensitive adhesive composition containing an MQT OH

[0003] Solventless addition-type silicone pressure-sensitive adhesive compositions have been disclosed, each comprising a resin component of the type and a platinum-based catalyst. However, these silicone pressure-sensitive adhesive compositions have the drawback that they are difficult to cure within a practical curing time unless the temperature is substantially higher than 100°C, and because the pressure-sensitive adhesive layer contains a large amount of the resin component, they are difficult to apply to applications requiring weak adhesion and easy peelability.

[0006] Patent Document 3 discloses a solventless ultraviolet-curable silicone pressure-sensitive adhesive composition containing an organopolysiloxane having a (meth)acrylic functional group, a monofunctional or polyfunctional acrylate monomer, an MQ-type organopolysiloxane resin, and a photopolymerization initiator, and its uses for temporary fixing, etc. However, this document does not disclose a composition containing an alkenyl group as the main component, and the composition disclosed in Patent Document 3 only produces a relatively hard pressure-sensitive adhesive layer that contains a large amount of resin, so there is a strong demand for a silicone pressure-sensitive adhesive that has low adhesion due to the rubber-like viscoelastic properties of the cured product.

[0007] In addition, the present applicants have proposed a solvent-free / low-solvent silicone pressure-sensitive adhesive composition containing a relatively low-molecular-weight organopolysiloxane resin and using a photoactivatable hydrosilylation reaction catalyst in Patent Document 4 (unpublished at the time of filing). However, there is no mention or suggestion of a radically polymerizable composition, and heating may be required to achieve a practical curing time.

[0008] JP 2004-327801 A (Patent Registration No. 4171898) JP 2012-041505 A (Patent Registration No. 5234064) International Publication (WO) No. 2018 / 225430 Pamphlet Patent Application No. 2020-216896 (unpublished at the time of filing)

[0009] The present invention has been made to solve the above problems, and aims to provide a curable organopolysiloxane composition that can be used to design a composition with a coatable viscosity even with a low solvent content, that can be used in industrial processes not only with commonly used heat curing processes but also with high-energy ray curing processes such as ultraviolet radiation, and that gives a cured product with excellent transparency and low adhesiveness, as well as an organopolysiloxane pressure-sensitive adhesive layer that is the cured product. Another aim of the present invention is to provide a laminate including the organopolysiloxane pressure-sensitive adhesive layer, and a method for producing a laminate that includes a bonding step between substrates.

[0010] As a result of extensive research, the present inventors have discovered that the above-mentioned problems can be solved by a curable organopolysiloxane composition containing 50 to 99 parts by mass of (A) a linear organopolysiloxane having two or more alkenyl groups per molecule, and 0.1 to 49.9 parts by mass of one or more radical-reactive components selected from (B) (B1) a monofunctional or polyfunctional vinyl monomer, and (B2) an organopolysiloxane compound having an organic group containing at least one acrylic or methacrylic group per molecule, wherein the sum of components (A) and (B2) is 50% by mass or more based on the total mass of the solids of the composition. This composition can be designed to have sufficient coatability even in solvent-free or low-solvent environments, and can be cured at high temperatures or cured at room temperature or low temperatures by irradiation with high-energy rays, depending on the radical polymerization initiator selected. Upon curing or semi-curing, the composition can form an organopolysiloxane pressure-sensitive adhesive layer with excellent transparency and low adhesion. The above-mentioned problems can also be solved by a laminate having an organopolysiloxane pressure-sensitive adhesive layer according to the present invention, and a method for producing a laminate including the steps of applying the curable organopolysiloxane composition onto a substrate and curing or semi-curing the composition.

[0011] The curable organopolysiloxane composition of the present invention can be designed to have a viscosity that allows coating even with a low solvent content, and by selecting the type of radical polymerization initiator (C), it can be used not only in industrially common heat curing processes but also in curing processes using high-energy rays such as ultraviolet light, and upon curing or semi-curing, it is possible to form an organopolysiloxane pressure-sensitive adhesive layer that is slightly adhesive, has excellent transparency, and exhibits little haze. Furthermore, the present invention can provide a laminate including the organopolysiloxane pressure-sensitive adhesive layer, and a method for producing a laminate including a bonding step between substrates.

[0012] The curable silicone composition of the present invention contains the above-mentioned components (A) to (C). From the standpoint of ease of handling, it may also optionally contain (D) an organic solvent, and may also contain a photosensitizer and other additives as long as they do not interfere with the objectives of the present invention. Each component is described below.

[0013] [Component (A)] Component (A) is a linear polysiloxane molecule containing at least two alkenyl groups within the molecule and serves as the base polymer of this composition. Examples of the alkenyl groups in the organopolysiloxane of 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 positions of the alkenyl groups in component (A) include, for example, the terminal and / or side chains of the molecular chain. From the standpoint of the technical effects of the present invention, it is preferable that at least a portion or all of component (A) have alkenyl groups bonded to silicon atoms at sites other than the terminals of the molecular chain. The use of a linear organopolysiloxane containing alkenyl groups in side chains of the molecular chain is one preferred embodiment of the present invention. Component (A) may contain a single component or a mixture of two or more different components.

[0014] In the organopolysiloxane of component (A), examples of organic groups bonded to silicon atoms other than alkenyl groups 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.

[0015] Unlike component (B), component (A) has a chain polysiloxane molecular structure. For example, component (A) is preferably linear or partially branched linear (branched), and may also contain a cyclic or three-dimensional network structure. Preferably, the main chain is a linear or branched diorganopolysiloxane consisting of repeating diorganosiloxane units, with both molecular chain terminals blocked with triorganosiloxy groups. The siloxane units that give branched organopolysiloxanes are T units or Q units, as described below.

[0016] The state of component (A) at room temperature may be oily or rubber-like; however, from the standpoint of coatability, particularly when the curable organopolysiloxane composition of the present invention is to be a solventless or low-solvent composition, it is preferable that component (A) be oily at room temperature, and the viscosity of component (A) at 25°C is preferably 1 mPa s or more and 100,000 mPa s or less, and in relation to the vinyl content described below, it is particularly preferable that the viscosity be 10 mPa s or more and 50,000 mPa s or less, to 10,000 mPa s or less. When the curable organopolysiloxane composition of the present invention is a solvent-based composition, at least a portion of component (A) may be a crude rubber-like alkenyl group-containing organopolysiloxane that has a viscosity of greater than 100,000 mPa s at 25°C or a plasticity, measured according to the method specified in JIS K6249 (measure the thickness of a 4.2 g spherical sample at 25°C when a load of 1 kgf is applied for 3 minutes, read to the nearest 1 / 100 mm, and multiply this value by 100), in the range of 50 to 200, and more preferably in the range of 80 to 180.

[0017] The content of alkenyl groups in component (A) is preferably in the range of 0.001 to 10% by mass, more preferably 0.005 to 5.0% by mass, and even more preferably 0.01 to 3.0% by mass, relative to the mass of component (A). In particular, vinyl (CH ２ The content of the (=CH-) moiety (hereinafter referred to as "vinyl content") is preferably in the range of 0.005 to 10.0 mass %, and it is particularly preferable to use an organosiloxane in which the content is in the range of 0.005 to 5.0 mass %.

[0018] Component (A) may contain, as an organic group other than the aliphatic unsaturated carbon-carbon bond-containing group, 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. From an industrial standpoint, it is particularly preferable for component (A) to contain a methyl group. On the other hand, from the standpoints of improving the elongation, adhesion to substrates, and transparency of the cured product, particularly at high temperatures, and particularly reducing the haze value, it is preferable that component (A) contains a methyl group as the organic group other than the aliphatic unsaturated carbon-carbon bond-containing group, and that the content of aryl or aralkyl groups is less than 0.1 mol %, and particularly 0.0 mol %, of all groups bonded to silicon atoms, so that component (A) is substantially free of aryl or aralkyl groups.

[0019] While component (A) may be a single component or a mixture of multiple components, from the viewpoint of the technical effects of the present invention, particularly the elongation of the cured product and adhesion to substrates, it may be a mixture containing (A1) a linear or branched organopolysiloxane having at least two alkenyl groups only at both molecular chain terminals, and (A2) a linear or branched organopolysiloxane having at least one alkenyl group at a site other than the molecular chain terminals and having at least three alkenyl groups per molecule, in a mass ratio of 30:70 to 70:30. Furthermore, components (A1) and (A2) may also be, and are preferred to be, mixtures of two or more components differing in viscosity, degree of siloxane polymerization, or alkenyl group content.

[0020] From the standpoint of preventing contact failure, etc., it is preferable that volatile or low-molecular-weight siloxane oligomers (octamethyltetrasiloxane (D4), decamethylpentasiloxane (D5), etc.) be reduced or removed from component (A). The extent of this can be designed as desired, but it may be less than 1 mass% of the entire component (A), less than 0.1 mass% for each siloxane oligomer, or even reduced to near the detection limit, if necessary.

[0021] [Component (B)] The composition of the present invention may contain one or more radical-reactive components selected from (B1) a monofunctional or polyfunctional vinyl monomer and (B2) an organopolysiloxane compound having an organic group containing at least one acrylic or methacrylic group in the molecule. Hereinafter, "(meth)acrylic acid" refers to both acrylic acid and methacrylic acid. Similarly, "(meth)acrylate," "(meth)acryloxy," and "(meth)acrylamide" refer to both acrylate and methacrylate, acryloxy and methacryloxy, and acrylamide and methacrylamide, respectively.

[0022] Like component (A), component (B) is a radically reactive component because it contains carbon-carbon unsaturated double bonds primarily derived from acrylic or methacrylic groups within its molecule, and like component (A), it participates in the curing reaction by radical polymerization. Therefore, by using component (B) in combination, it is possible to adjust the adhesion to substrates and the crosslink density of the cured product, and depending on the amount of component (B) used, it is possible to adjust the hardness and adhesion to substrates of the organopolysiloxane pressure-sensitive adhesive layer obtained by curing or semi-curing the composition so that it has slight adhesion, making it particularly useful for improving the curing rate, adjusting the crosslink density, and adjusting the adhesion to substrates.

[0023] The amount of the radical-reactive component (B) used is within the range of 0.1 to 49.9 parts by mass, and particularly preferably 0.1 to 25 parts by mass, per 50 to 99 parts by mass of component (A). In particular, the composition of the present invention requires that the sum of components (A) and (B2) be 50% by mass or more relative to the total mass of the solids. If the content of component (B) exceeds the upper limit, the organopolysiloxane pressure-sensitive adhesive layer obtained by curing the composition tends to be hard and brittle, making it insufficient for use as a low-tack pressure-sensitive adhesive layer. Furthermore, the transparency of the pressure-sensitive adhesive layer is impaired, making it prone to cloudiness (haze). On the other hand, if the content of component (B) is below the lower limit, adjustment of the curing rate, crosslink density, etc. of the organopolysiloxane pressure-sensitive adhesive layer may be insufficient, preventing the desired low-tack pressure-sensitive adhesive layer from being achieved.

[0024] The component (B1) is a vinyl monomer, which is the starting material for organic resins generally called vinyl resins, and examples thereof include lower alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, and isopropyl (meth)acrylate; glycidyl (meth)acrylate; n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-hexyl (meth)acrylate, cyclohexyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. Higher (meth)acrylates such as methyl (meth)acrylate, isoamyl (meth)acrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, isobornyl (meth)acrylate, stearyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, 3,3,5-tricyclohexyl (meth)acrylate, and phenoxyethyl (meth)acrylate; lower fatty acid vinyl esters such as vinyl acetate and vinyl propionate; vinyl butyrate and vinyl 2-ethyl caproate Higher fatty acid esters such as vinyl hexanoate, vinyl laurate, and vinyl stearate; aromatic vinyl monomers such as styrene, vinyl toluene, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, and vinylpyrrolidone; amide group-containing vinyl monomers such as (meth)acrylamide, N-methylol (meth)acrylamide, N-methoxymethyl (meth)acrylamide, isobutoxymethoxy (meth)acrylamide, and N,N-dimethyl (meth)acrylamide; 2-hydroxyethyl (meth)acrylate, 4- Hydroxyl group-containing vinyl monomers such as hydroxybutyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and tetrahydrofurfuryl (meth)acrylate; fluorine-containing vinyl monomers such as trifluoropropyl (meth)acrylate, perfluorobutylethyl (meth)acrylate, and perfluorooctylethyl (meth)acrylate; epoxy group-containing vinyl monomers such as glycidyl (meth)acrylate and 3,4-epoxycyclohexylmethyl (meth)acrylate;Carboxylic acid-containing vinyl monomers such as (meth)acrylic acid, itaconic acid, crotonic acid, fumaric acid, and maleic acid; ether bond-containing vinyl monomers such as tetrahydrofurfuryl (meth)acrylate, butoxyethyl (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, polyethylene glycol (meth)acrylate, polypropylene glycol mono(meth)acrylate, hydroxybutyl vinyl ether, cetyl vinyl ether, 2-ethylhexyl vinyl ether, diethylene glycol monoethyl ether (meth)acrylate, and diethylene glycol monomethyl ether (meth)acrylate; unsaturated group-containing silicone compounds such as (meth)acryloxypropyltrimethoxysilane and polydimethylsiloxane having a styryl group at one end; butadiene Examples include: vinyl chloride; vinylidene chloride; (meth)acrylonitrile; dibutyl fumarate; maleic anhydride; dodecyl succinic anhydride; (meth)acrylic glycidyl ether; alkali metal salts, ammonium salts, and organic amine salts of radically polymerizable unsaturated carboxylic acids such as (meth)acrylic acid, itaconic acid, crotonic acid, fumaric acid, and maleic acid; radically polymerizable unsaturated monomers having a sulfonic acid group such as styrenesulfonic acid, and alkali metal salts, ammonium salts, and organic amine salts thereof; quaternary ammonium salts derived from (meth)acrylic acid such as 2-hydroxy-3-methacryloxypropyltrimethylammonium chloride; methacrylic acid esters of alcohols having a tertiary amine group such as methacrylic acid diethylamine ester, and quaternary ammonium salts thereof;

[0025] Similarly, polyfunctional vinyl monomers can also be used, such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 1,4-bis((meth)acryloyloxy)butane, 1,6-bis((meth)acryloyloxy)hexane, 1,9-bis((meth)acryloyloxy)nonane, 1,12-bis((meth)acryloyloxy)dodecane, tris(2-acryloyloxy)ethyl isosialate, pentaerythritol tetraacrylate, trimethylolpropane tri(meth)acrylate, pentyl glycol di ... Examples include di(meth)acrylate of diol of an adduct of bisphenol A with ethylene oxide or propylene oxide, di(meth)acrylate of diol of an adduct of hydrogenated bisphenol A with ethylene oxide or propylene oxide, (meth)acryloyl group-containing monomers such as triethylene glycol divinyl ether, and unsaturated group-containing silicone compounds such as polydimethylsiloxane capped at both ends with styryl groups.

[0026] In the present invention, the preferred component (B1) is an acrylate vinyl monomer having one acryloxy group, and can be used alone or in combination of two or more types, taking into consideration the viscosity, curability, hardness after curing, and glass transition temperature of the compound. Among these, acrylate compounds or methacrylate compounds having 8 or more carbon atoms in the molecule, preferably 8 to 30 carbon atoms, are preferred from the viewpoint of providing low volatility, low viscosity of the composition, and high glass transition temperature of the cured product. More specifically, a vinyl monomer selected from dodecyl acrylate, 2-ethylhexyl acrylate, isobornyl acrylate, and dicyclopentanyl acrylate is preferred.

[0027] Similarly, suitable components (B1) are acrylate vinyl monomers having two acryloxy groups, which can be used alone or in combination of two or more, taking into consideration the viscosity of the compound, curability, compatibility with the compound having one acryloxy group, and hardness and glass transition temperature after curing. Diethylene glycol diacrylate, 1,6-bis(acryloyloxy)hexane, trimethylolpropane triacrylate, and polydimethylsiloxane having acryloxy functionality at both ends are preferably used.

[0028] Furthermore, taking into consideration the above physical properties, it is also possible to use a compound having two or more acryloxy groups in combination with a compound having one acryloxy group.In this case, the two can be combined in any ratio, but usually, the ratio of [compound having two or more acryloxy groups] / [compound having one acryloxy group] is in the range of 1 / 99 to 50 / 50 (mass ratio).This is because if the ratio of the compound having two or more acryloxy groups is too high, the cured product tends to be hard and brittle.

[0029] Component (B2) is an organopolysiloxane compound having an organic group containing at least one acrylic or methacrylic group in the molecule, and any of the following can be used: resinous, chain (including linear and branched), cyclic, and resin-linear block copolymers composed of resinous blocks and chain blocks.

[0030] Preferably, the component (B2) has a structure represented by the general formula (1): at the end or side chain of the molecular chain: A silicon atom-bonded functional group R represented by Ａ In the formula, R １ are each independently a hydrogen atom, a methyl group, or a phenyl group, and are preferably a hydrogen atom or a methyl group to form an acrylic or methacrylic group moiety. Z is a divalent organic group which may contain a heteroatom and is bonded to a silicon atom which constitutes the main chain of the polysiloxane represented by *, and may be a divalent organic group which may contain a silicon atom, an oxygen atom, a nitrogen atom, or a sulfur atom.

[0031] where Z is an alkylene group having 2 to 22 carbon atoms; ３ -C(=O)-OR ４ - {wherein R ３ is an alkylene group having 2 to 22 carbon atoms, and R ４ is a group selected from an ethylene group, a propylene group, a methylethylene group, or a hexylene group; １ -X-C(=O)-X-Z ２ a divalent organic group represented by the formula - {wherein Z １ Ha -O(CH ２ ) ｋ - (k is a number ranging from 0 to 3), and X represents an oxygen atom, a nitrogen atom, or a sulfur atom. ２ is bonded to a silicon atom constituting the main chain of polysiloxane, where * is -[(CH ２ ) ２ O] ｍ (C ｎ H ２ｎ )-(m is a number ranging from 0 to 3, and n is a number ranging from 2 to 10)}, and —Z １ -R ２ ２ Si—O—R ２ ２ Si-Z ２ Preferably, the linking group is any one of the groups selected from the following divalent linking groups:

[0032] Particularly preferably, the silicon atom-bonded functional group (R Ａ ) is represented by the general formula (1): In the formula, R １ R each independently represents a hydrogen atom, a methyl group, or a phenyl group, and is preferably a hydrogen atom or a methyl group. ２ are each independently an alkyl group or an aryl group, and from an industrial standpoint, an alkyl group having 1 to 20 carbon atoms or a phenyl group is preferred, and a methyl group is particularly preferred. １ Ha -O(CH ２ ) ｍ - (m is a number ranging from 0 to 3), and m is preferably 1 or 2. Z ２ is bonded to a silicon atom constituting the main chain of polysiloxane, where * is -Cｎ H ２ｎ - (n is a number ranging from 2 to 10), and those in which n is 2 to 6 are practically preferred. Ａ ) is a silicon atom-bonded functional group (R Ａｌｋ The (meth)acrylic functional group can be introduced into a molecule by reacting the (meth)acrylic functional group with a hydrosilane compound having a silicon-bonded hydrogen atom and a (meth)acrylic functional group in the molecule (e.g., 3-(1,1,3,3-tetramethyldisiloxanyl)propyl methacrylate) in the presence of a hydrosilylation catalyst. This reaction may be, and is preferably, carried out in the presence of a polymerization inhibitor such as dibutylhydroxytoluene (BHT).

[0033] More specifically, the component (B2) may contain one or more linear organopolysiloxanes selected from the following components (B2-1-1) and (B2-1-2).

[0034] The component (B2-1-1) is a functional group (R Ａ ) in the molecule.

[0035] Structural formula:

[0036] In the formula, R １ are each independently a C1 to C6 alkyl group, a C2 to C20 alkenyl group, or a C6 to C12 aryl group; R Ａ’ are each independently a C1 to C6 alkyl group, a C2 to C20 alkenyl group, a C6 to C12 aryl group, and a silicon atom-bonded functional group (R Ａ ), n1 is a positive number, and n2 is 0 or a positive number. However, when n2 is 0, R Ａ’ At least one of the groups is a silicon atom-bonded functional group (R Ａ) n1+n2 is a positive number of 0 or greater, and is not limited, but is preferably in the range of 10 to 5000, more preferably 10 to 2000, and even more preferably 10 to 1000. The value of n1+n2 may be, and is preferably, a number such that the viscosity of component (C'1) at 25°C falls within the range of 1 to 100,000 mPa s, more preferably 10 to 50,000 mPa s, and even more preferably 500 to 50,000 mPa s.

[0037] The component (B2-1-2) has a functional group (R Ａ ) in the molecule and containing a branched siloxane unit.

[0038] Average unit formula: (R Ａ’ R １ ２ SiO １／２ ) x (R １ ２ SiO ２／２ ) ｙ１ (R Ａ’ R １ SiO ２／２ ) ｙ２ (R １ SiO ３／２ ) ｚ１ (R Ａ’ SiO ３／２ ) ｚ２ (I-2)

[0039] In the above formula, R １ , R Ａ’ is the same group as above, and x, y1, y2, z1, and z2 represent the ratio of the amount of substance when the sum of the siloxane units is 1. Specifically, when all of the following conditions are satisfied: x + y1 + y2 + z1 + z2 = 1, 0 < x ≦ 0.2, 0.3 ≦ y1 + y2 < 1, 0 < z1 + z2 ≦ 0.2, and y2 + z2 = 0, R Ａ’ At least one of the groups is a silicon atom-bonded functional group (R Ａ ) Either or both of y2 and z2 may be 0.

[0040] More specifically, the component (B2-1-2) is a branched-chain organopolysiloxane represented by the following siloxane unit formula: (R Ａ’ R １ ２ SiO １／２ ) a (R １ ２ SiO ２／２ ) b１ (R Ａ’ R １ SiO ２／２ ) b２ (R １ SiO ３／２ ) c１ (R Ａ’ SiO ３／２ ) c２ (In the formula, R １ , R Ａ’ are the same groups as above), 0<a≦10, 15≦b1+b2<2000, 0<c1+c2≦10, and when b2+c2=0, R Ａ’ At least one of the groups is a silicon atom-bonded functional group (R Ａ )

[0041] As an example, the component (B2-1-2) may be a branched-chain organopolysiloxane having a methacryloyl group-containing organic group only on the terminal M unit represented by the following siloxane unit formula: (R Ａ’ R １ ２ SiO １／２ ) a (R １ ２ SiO ２／２ ) b１ (R １ SiO ３／２ ) c１ In the formula, R １ , R Ａ’ is the same group as above, 0<a≦10, 15≦b1<2000, 0<c1≦10, R Ａ’ At least one of the groups is a silicon atom-bonded functional group (R Ａ )

[0042] The viscosity of component (B2-1-2) at 25°C is preferably 10 to 50,000 mPa·s, and more preferably 100 to 2,000 mPa·s.

[0043] Examples of the component (B2) that are widely available on the market include (branched or linear) polydimethylsiloxanes containing a (meth)acrylic group at one end, and polydimethylsiloxanes blocked at both ends with methacryloxypropyl.

[0044] [Siloxane Mass % of Composition] The curable organopolysiloxane composition of the present invention comprises component (A), a linear reactive siloxane component, and optionally (B2), an organopolysiloxane compound having an organic group containing at least one acrylic or methacrylic group in the molecule. The sum of the masses of components (A) and (B2) relative to the total mass of the solids of the composition (components that form the organopolysiloxane pressure-sensitive adhesive layer upon curing, excluding organic solvents), can be defined as the "siloxane mass % of the composition." When this siloxane mass % is 50 mass % or more, preferably 55 to 99.5 mass %, and more preferably 60 to 99.5 mass %, the organopolysiloxane pressure-sensitive adhesive layer of the present invention can be designed to have a transparent appearance, the flexibility characteristic of silicone, and slight adhesion resulting from the viscoelastic properties of the cured product.

[0045] [Organopolysiloxane Resin Other Than Component (A) and Component (B2)] The composition of the present invention may contain an organopolysiloxane resin other than component (A) and component (B2) to the extent that the technical effect of the present invention, i.e., slight adhesion, can be achieved. Such an organopolysiloxane resin is a component that adjusts the adhesive strength, i.e., the adhesion strength to a substrate, and it is possible to adjust the hardness of the cured product of the composition and its adhesion to a substrate depending on the amount of this component used.

[0046] Such organopolysiloxane resins contain R ３ SiO １／２ (wherein R each independently represent a monovalent organic group), and a siloxane unit (M unit) represented by SiO ４／２An example is an organopolysiloxane resin containing siloxane units (Q units) represented by the following formula: Here, the molar ratio of M units to Q units may be 0.5 to 2.0. If this molar ratio is less than 0.5, the adhesion of the cured product to the substrate may decrease, while if it is more than 2.0, the cohesive force of the substance constituting the adhesive layer decreases.

[0047] On the other hand, from the viewpoint of low adhesiveness, it is preferable that the curable organopolysiloxane composition of the present invention contains little or substantially no organopolysiloxane resin as described above. Specifically, in the curable organopolysiloxane composition of the present invention, the mass ratio of the organopolysiloxane resin to the sum of the linear reactive siloxane components (Component (A) and Component (B2) described below) (= [mass of organopolysiloxane resin] / [sum of masses of Component (A) + Component (B2)]) is preferably in the range of 0 to 0.1, more preferably 0 to 0.05, and most preferably 0, i.e., the composition is substantially free of organopolysiloxane resin. If the organopolysiloxane resin content exceeds the upper limit, the adhesive strength and bonding strength of the cured organopolysiloxane pressure-sensitive adhesive layer derived from the organopolysiloxane resin will be so strong that the pressure-sensitive adhesive layer may not have low adhesiveness.

[0048] [Component (C)] Component (C) is a radical polymerization initiator and may be a (C1) photoradical polymerization initiator, a (C2) thermal radical polymerization initiator, or a combination thereof. The type of component (C), curing method, and curing temperature may be selected appropriately depending on the curing and adhesion process of the curable organopolysiloxane composition of the present invention, the heat resistance of the substrate, the energy reduction requirements, etc. Because the composition of the present invention contains alkenyl groups in component (A), the main component, it can achieve good curability by irradiation with high-energy rays and / or heating in the presence of component (C).

[0049] The amount of component (C) used is 0.1 to 10 parts by mass, and particularly preferably 0.2 to 5 parts by mass, when the mass of component (A) is 30 to 99 parts by mass. The amount of component (C) used can be appropriately designed within the above range depending on the formation process and curing time of the pressure-sensitive adhesive layer to which the composition is applied, the content of alkenyl groups derived from component (A), and the irradiation dose and / or heating conditions of high-energy rays.

[0050] The component (C1) is a photoradical polymerization initiator that accelerates the photocuring reaction of the alkenyl group in the component (A) and, optionally, the thiol compound (E) when irradiated with high-energy rays such as ultraviolet rays.

[0051] Although known photoradical polymerization initiators are roughly divided into photocleavage type and hydrogen abstraction type, the photoradical polymerization initiator used in the composition of the present invention can be arbitrarily selected from those known in the art and is not particularly limited to a specific one. Note that some photoradical polymerization initiators can promote the curing reaction not only by irradiation with high-energy rays such as ultraviolet rays but also by irradiation with light in the visible light region.

[0052] Specific examples of the photoradical polymerization initiator include α-ketol compounds such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, and 1-hydroxycyclohexylphenyl ketone; acetophenone compounds such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, and 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane-1; benzoin ether compounds such as benzoin ethyl ether, benzoin isopropyl ether, and anisoin methyl ether; and benzyldimethyl ether. aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; photoactive oxime compounds such as 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; benzophenone compounds such as benzophenone, benzoylbenzoic acid, and 3,3'-dimethyl-4-methoxybenzophenone; thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone; camphorquinone; and halogenated ketones.

[0053] Similarly, examples of photoradical polymerization initiators suitable as the component (C1) in the present invention include bis-(2,6-dichlorobenzoyl)phenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-2,5-dimethylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide. side, bis(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide, bis(2,6-dichlorobenzoyl)-2,5-dimethylphenylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide, bis-(2,4,6-trimethylbenzoyl)-phenylphosphine oxide and other bisacylphosphine oxides; 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,6-dichlorobenzoyldiphenyl Phosphine oxide, monoacylphosphine oxides such as 2,4,6-trimethylbenzoylphenylphosphinic acid methyl ester, 2-methylbenzoyldiphenylphosphine oxide, pivaloylphenylphosphinic acid isopropyl ester, and 2,4,6-trimethylbenzoyldiphenylphosphine oxide; anthraquinone, chloroanthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, and 2-amyl anthraquinone. Anthraquinones such as anthraquinone and 2-aminoanthraquinone; benzoic acid esters such as ethyl-4-dimethylaminobenzoate, 2-(dimethylamino)ethyl benzoate, and p-dimethylbenzoic acid ethyl ester; titanocenes such as bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl)titanium and bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(1-pyr-1-yl)ethyl)phenyl]titanium;Examples include phenyl disulfide 2-nitrofluorene, butyroin, anisoin ethyl ether, azobisisobutyronitrile, and tetramethylthiuram disulfide;

[0054] Commercially available acetophenone-based photopolymerization initiators suitable as component (C1) in the present invention include Omnirad 907, 369, 369E, and 379 manufactured by IGM Resins. Commercially available acylphosphine oxide-based photopolymerization initiators include Omnirad TPO, TPO-L, and 819 manufactured by IGM Resins. Commercially available oxime ester-based photopolymerization initiators include Irgacure OXE01 and OXE02 manufactured by BASF Japan Ltd., N-1919 and ADEKA Arcles NCI-831 and NCI-831E manufactured by ADEKA Corporation, and TR-PBG-304 manufactured by Changzhou New Advanced Electronic Materials Co., Ltd.

[0055] Component (C2) is a thermal radical polymerization initiator that generates radical species upon heating and promotes the thermal curing reaction of the alkenyl groups in component (A) and, optionally, the thiol compound (E). Examples of such thermal radical polymerization initiators include azo compounds and organic peroxides.

[0056] Examples of azo compounds include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 1,1'-azobis-1-cyclohexanecarbonitrile, dimethyl-2,2'-azobisisobutyrate, dimethyl-2,2'-azobis(2-methylpropionate), dimethyl-1,1'-azobis(1-cyclohexanecarboxylate), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-amidinopropane) dihydrochloride, 2-tert-butylazo-2-cyanopropane, 2,2'-azobis(2-methylpropionamide) dihydrate, and 2,2'-azobis(2,4,4-trimethylpentane).

[0057] Examples of organic peroxides include alkyl peroxides, diacyl peroxides, peroxide esters, and carbonate peroxides. Specific examples of alkyl peroxides include dicumyl peroxide, di-tert-butyl peroxide, di-tert-butylcumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3, tert-butylcumyl, 1,3-bis(tert-butylperoxyisopropyl)benzene, and 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxonane. Examples of diacyl peroxides include benzoyl peroxide, lauroyl peroxide, and decanoyl peroxide. Examples of peroxide esters include 1,1,3,3-tetramethylbutylperoxyneodecanoate, α-cumylperoxyneodecanoate, tert-butylperoxyneodecanoate, tert-butylperoxyneoheptanoate, tert-butylperoxypivalate, tert-hexylperoxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, and tert-amylperoxy-2-ethylhexanoate. , tert-butylperoxy-2-ethylhexanoate, tert-butylperoxyisobutyrate, di-tert-butylperoxyhexahydroterephthalate, tert-amylperoxy-3,5,5-trimethylhexanoate, tert-butylperoxy-3,5,5-trimethylhexanoate, tert-butylperoxyacetate, tert-butylperoxybenzoate, and di-butylperoxytrimethyladipate are examples. Examples of peroxycarbonates include di-3-methoxybutyl peroxydicarbonate, di(2-ethylhexyl) peroxydicarbonate, diisopropyl peroxycarbonate, tert-butylperoxyisopropyl carbonate, di(4-tert-butylcyclohexyl) peroxydicarbonate, dicetyl peroxydicarbonate, and dimyristyl peroxydicarbonate.

[0058] [Component (C'): Photosensitizer] The present composition may optionally contain a photosensitizer (C') in combination with the photoradical polymerization initiator (C1). The use of a sensitizer can increase the photon quantum efficiency of the polymerization reaction, allowing longer wavelength light to be utilized in the polymerization reaction compared to when a photoinitiator alone is used. This is known to be particularly effective when the composition is coated to a relatively thick thickness or when a relatively long wavelength LED light source is used. Known sensitizers include anthracene-based compounds, phenothiazine-based compounds, perylene-based compounds, cyanine-based compounds, merocyanine-based compounds, coumarin-based compounds, benzylidene ketone-based compounds, (thio)xanthene or (thio)xanthone-based compounds, such as isopropylthioxanthone, 2,4-diethylthioxanthone, squarylium-based compounds, (thia)pyrylium-based compounds, and porphyrin-based compounds. However, any photosensitizer can be used in the curable organopolysiloxane composition and pressure-sensitive adhesive composition of the present invention, without limitation. The amount used is arbitrary, but is generally selected so that the mass ratio of component (C') to component (C1) is in the range of 0 to 10, and when used, is in the range of 0.01 to 5.

[0059] [Selection of Component (C) and Curing Method] Because the present composition contains the above-described components (A) and (B), it forms a cured product by a radical polymerization reaction. Here, when at least a portion of component (C) is a photoradical polymerization initiator (C1), the present composition can be cured by irradiating it with high-energy rays such as ultraviolet rays. Similarly, when at least a portion of component (C) is a thermal radical polymerization initiator (C2), the present composition can be cured by heating. Furthermore, by combining the two, it is possible to selectively or combinedly cure the composition by heating and high-energy ray irradiation, and these can be appropriately selected depending on the desired curing method and sealing process.

[0060] In particular, the composition according to the present invention is solvent-free or low-solvent, and at least a portion of the component (C) is a photoradical polymerization initiator (C1), and optionally further contains a photosensitizer (C'), which has the advantages of low environmental impact, enabling a rapid curing reaction even at low temperatures, including room temperature, even for substrates or members with poor heat resistance, and making it suitable for use in industrial production processes that respond to the trend toward low energy consumption in fields such as semiconductors. On the other hand, when at least a portion of the component (C) is a thermal radical polymerization initiator (C2), there is the advantage that rapid curing is possible at high temperatures in a short period of time.

[0061] [(D) Organic Solvent and Low-Solvent / Solvent-Free Compositions] The curable organopolysiloxane composition of the present invention can be designed as a low-solvent or solvent-free composition by selecting its constituent components (particularly by selecting components with a low viscosity as component (A) overall). Even compositions containing a small amount of (D) organic solvent or substantially no organic solvent can be designed to have practically sufficient coatability. Specifically, the organic solvent content is preferably 0 to less than 60% by mass, less than 50% by mass, and substantially within the range of 0 to 30% by mass, based on 100 parts by mass of the total composition. Meanwhile, the inclusion of a small amount of organic solvent is permissible when it is necessary to improve the wettability of the composition to the substrate or when it is unavoidably included as a solvent accompanying other components. The type and amount of organic solvent are adjusted taking into account factors such as coating operability, but from the standpoint of designing a solvent-free composition, it is preferable to use as little as possible.

[0062] More specifically, when the total amount (= sum) of components (A), (B), and (C), and optionally other non-volatile components, which form the solid content of the curable organopolysiloxane composition of the present invention upon curing, is taken as 100 parts by mass, the total amount of component (D), which serves as a diluent, is in the range of 0 to 100 parts by mass, and preferably in the range of 0 to 25 parts by mass.

[0063] In the present invention, examples of the organic solvent (D) 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 oils. Two or more of these may be used in combination depending on the wettability of the sheet-like substrate.

[0064] [(E) Thiol Compound] The composition according to the present invention may further contain (E) a polyfunctional thiol compound having at least two thiol groups (—SH) in the molecule. The polyfunctional thiol compound acts as a chain transfer agent to promote a radical polymerization reaction. Therefore, particularly when a part of component (C) according to the present invention is a photoradical polymerization initiator and the present composition is cured by irradiation with high-energy rays such as ultraviolet rays, the polyfunctional thiol compound can improve the curing rate and deep curability of the cured product even when the irradiation dose of high-energy rays is small, and also functions as a crosslinking point in the present composition.

[0065] Examples of such polyfunctional thiol compounds include pentaerythritol tetrakis(3-mercaptobutyrate), 1,4-bis(3-mercaptobutyryloxy)butane, 1,3,5-tris(2-(3-sulfanylbutanoyloxy)ethyl)-1,3,5-triazinane-2,4,6-trione, and trimethylolpropane tris(3-mercaptobutyrate).

[0066] Component (E) may also be an organopolysiloxane compound having an organic group containing at least two thiol groups within the molecule. Resinous, chain (including linear and branched), cyclic, and resin-linear block copolymers composed of resinous blocks and chain blocks can all be used. In the thiol group-containing organopolysiloxane compound of component (E), the bonding site of the thiol-modified group is not particularly limited, and it may be either at the molecular chain end or at the side chain. An example is a linear organopolysiloxane having a thiol-modified group at the side chain, such as a dimethylsiloxane-2-thiolpropylmethylsiloxane copolymer whose molecular chain end is capped with a trimethylsiloxy group. In particular, when component (E) is a thiol group-containing organopolysiloxane compound, compatibility with other components, the uniformity and viscosity of the entire composition can be improved, and the intramolecular crosslink density, etc., can be adjusted.

[0067] The use of component (E) is optional, but the amount used is 0 to 20 parts by mass, preferably 0 to 10 parts by mass, and particularly preferably 0 to 5 parts by mass, relative to 50 to 99 parts by mass of component (A).

[0068] [(A') Linear Organopolysiloxane Containing No Carbon-Carbon Double Bond-Containing Reactive Group in the Molecule] The curable organopolysiloxane composition of the present invention can be blended with a non-reactive organopolysiloxane, such as a 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. This may improve the loss factor (tan δ), storage modulus (G'), and loss modulus (G'') of the organopolysiloxane pressure-sensitive adhesive layer. For example, the use of a polydimethylsiloxane or polydimethyldiphenylsiloxane having terminal hydroxyl groups can increase the loss factor of the cured layer, and such compositions are encompassed within the scope of the present invention.

[0069] The curable organopolysiloxane composition of the present invention may optionally contain components other than those described above, provided that the technical effects of the present invention are not impaired. For example, the composition may contain adhesion promoters; antioxidants such as phenols, quinones, amines, phosphorus, phosphites, sulfur, or thioethers; light stabilizers such as triazoles or benzophenones; flame retardants such as phosphate esters, halogens, phosphorus, or antimony; one or more antistatic agents such as cationic surfactants, anionic surfactants, or nonionic surfactants; polymerization inhibitors; and ultraviolet absorbers. In addition to these components, pigments, dyes, and inorganic fine particles (reinforcing fillers, dielectric fillers, conductive fillers, thermally conductive fillers) that may be optionally surface-treated may also be optionally blended.

[0070] The method for preparing the curable organopolysiloxane composition of the present invention is not particularly limited, and can be carried out by homogeneously mixing the respective components. If necessary, an organic solvent may be added, and the composition may be prepared by mixing using a known stirrer or kneader. Depending on the type of component (C), the composition may exhibit radical polymerizability upon heating. In such cases, mixing is preferably carried out at a temperature below 200°C, preferably below 150°C.

[0071] [Viscosity of the Overall Composition] From the standpoint of coatability and handling as an adhesive or an adhesive-forming composition, the curable organopolysiloxane composition of the present invention has a viscosity at 25°C of the overall composition in the range of 1,000 to 300,000 mPa·s, preferably 5,000 to 50,000 mPa·s. In particular, when the content of organic solvent is 30 mass% or less per 100 parts by mass of the composition, the viscosity of the overall composition is preferably 5,000 to 300,000 mPa·s. Such compositions can achieve practically sufficient coatability even in low-solvent or solvent-free types.

[0072] [Method of Use as an Adhesive] The curable organopolysiloxane composition of the present invention contains the aforementioned components (A), (B), and (C), and can be cured by one or more radical polymerization reactions selected from (i) a heat curing reaction and (ii) a photocuring reaction by irradiation with high-energy rays. Here, an organopolysiloxane pressure-sensitive adhesive layer that adheres to a substrate can be formed in either the form of a cured product in which the curing reaction has been completed or a semi-cured product in which the composition retains curing reactivity. When the expression "curing or semi-curing the curable organopolysiloxane composition" is used in the present invention, "cured" refers to a state in which the radical polymerization reaction has been completed in the organopolysiloxane pressure-sensitive adhesive layer, and "semi-cured" refers to a state in which a solid organopolysiloxane pressure-sensitive adhesive layer has been formed but the pressure-sensitive adhesive layer retains radical polymerization reactivity and can undergo further curing by heating and irradiation with high-energy rays. The reaction for forming a semi-cured organopolysiloxane pressure-sensitive adhesive layer and the reaction for forming a subsequent cured organopolysiloxane pressure-sensitive adhesive layer may be the same or different radical polymerization reactions, or two or more types of radical polymerization reactions may be carried out simultaneously. For example, a semi-cured organopolysiloxane pressure-sensitive adhesive layer may be formed by a heat curing reaction, and then a completely cured organopolysiloxane pressure-sensitive adhesive layer may be formed by irradiation with high-energy rays. Alternatively, the same curing reaction may be carried out in stages by temporarily interrupting and then resuming heating or high-energy radiation irradiation to form a semi-cured / cured organopolysiloxane pressure-sensitive adhesive layer.

[0073] Here, when the organopolysiloxane pressure-sensitive adhesive layer in a "semi-cured" state undergoes one or more radical polymerization reactions selected from (i) a heat curing reaction and (ii) a photocuring reaction by irradiation with high-energy rays, the crosslink density of the adhesive layer changes as the layer changes to a "cured" state, which may change the adhesive strength to the substrate. For example, by curing the organopolysiloxane pressure-sensitive adhesive layer in a "semi-cured" state by allowing the radical polymerization reaction to proceed while the layer is in contact with the substrate, the fully cured pressure-sensitive adhesive layer may exhibit stronger adhesive strength to the substrate than at the time of contact and form a strong bond. Conversely, if the crosslink density of the organopolysiloxane pressure-sensitive adhesive layer increases due to curing, and the adhesive strength to the substrate decreases, the adhesive strength to the substrate may also decrease compared to the time of contact, allowing the layer to be easily peeled off. The former is particularly advantageous when forming a permanent adhesive layer as a bonding layer between substrates, while the latter is advantageous when, for example, it functions as a weak adhesive layer that temporarily fixes substrates together in a process, such as a process protection film, and when it is necessary to reduce the adhesive strength of the adhesive layer by irradiating it with high-energy rays in a later process, thereby enabling it to be easily peeled from the substrate. These methods of use that involve changing the adhesive strength are methods of use that the applicants clearly intend and teach for the curable organopolysiloxane composition and organopolysiloxane adhesive layer of the present invention.

[0074] [Coating and Curing] The curable organopolysiloxane composition of the present invention forms a coating film by coating on a substrate, and then forms an organopolysiloxane pressure-sensitive adhesive layer as a cured or semi-cured product through one or more radical polymerization reactions selected from (i) a heat curing reaction and (ii) a photocuring reaction by irradiation with high-energy rays.

[0075] Examples of coating methods include gravure coating, offset coating, offset gravure, roll coating, reverse roll coating, air knife coating, curtain coating, and comma coating. The amount of coating can be designed to a desired thickness depending on the application of the pressure-sensitive adhesive layer and the display device, etc. For example, the thickness of the pressure-sensitive adhesive layer after curing is 1 to 1,000 μm, or may be 5 to 900 μm, or may be 10 to 800 μm, but is not limited to these.

[0076] When the curable organopolysiloxane composition of the present invention is cured by (i) a heat curing reaction, heating is performed at a temperature of 80 to 200°C, preferably 100°C or higher, and more preferably 100 to 180°C, to produce a slightly adhesive cured or semi-cured pressure-sensitive adhesive layer through a thermal radical polymerization reaction. The heating time required for curing can be selected appropriately depending on the degree of curing, the thickness of the pressure-sensitive adhesive layer, and the amount of catalyst used, but is generally in the range of 0.5 to 90 minutes. By interrupting or gradually heating, an organopolysiloxane pressure-sensitive adhesive layer in the form of a semi-cured product that retains heat curing reactivity can be obtained. The heating temperature and heating time can be selected appropriately depending on the heat resistance of the substrate, the sealing process, etc.

[0077] When the curable organopolysiloxane composition of the present invention is cured by (ii) a photocuring reaction induced by irradiation with high-energy rays, usable high-energy rays include ultraviolet rays, gamma rays, X-rays, α rays, and electron beams, with ultraviolet rays being preferred from the viewpoint of practicality. Suitable sources of ultraviolet rays include high-pressure mercury lamps, medium-pressure mercury lamps, Xe—Hg lamps, and deep UV lamps. UV irradiation with a wavelength of 280 to 400 nm, preferably 300 to 400 nm, is particularly preferred, and light sources having multiple emission bands may also be used.

[0078] The dose of high-energy radiation varies depending on the type and amount of (C1) photoradical polymerization initiator and the degree of curing reaction. In the case of ultraviolet light, the cumulative dose at a wavelength of 365 nm is 100 mJ / cm. ２ ~100 J / cm ２It is preferable that the wavelength of the high-energy ray is within the above range. Note that the high-energy ray may be irradiated through the substrate supporting the pressure-sensitive adhesive layer according to the present invention, as long as the substrate does not absorb electromagnetic waves in the above wavelength range. In other words, as long as a certain amount of irradiation can be achieved, the high-energy ray may be irradiated through the substrate or a cover material such as a protective film.

[0079] Because the curing reaction does not require heating, curing can be achieved at low temperatures (15 to 100°C), including room temperature (25°C). In the present embodiment, "low temperature" refers to, for example, 100°C or lower, specifically, a temperature range of 15 to 100°C, and temperatures of 80°C or lower are also acceptable. When the reaction of the composition (including semi-cured product) of the present invention is allowed to proceed at a temperature range of 15 to 100°C, the composition may be left standing at approximately room temperature (a temperature range that can be reached without heating or cooling, particularly a temperature range of 20 to 25°C), cooled to 15°C or higher below room temperature, or heated to 100°C or higher above room temperature. The time required for the curing reaction can be appropriately designed depending on the irradiation dose and temperature of high-energy rays such as ultraviolet rays. Furthermore, by interrupting irradiation before a predetermined cumulative irradiation dose is reached, an organopolysiloxane pressure-sensitive adhesive layer in the form of a semi-cured product that retains photocuring reactivity may be obtained.

[0080] The organopolysiloxane pressure-sensitive adhesive layer obtained by the above curing reaction is slightly adhesive, and it is possible to design a pressure-sensitive adhesive layer having an adhesive strength of 5 to 50 gf / 25 mm, preferably 5 to 40 gf / 25 mm, measured, for example, by a 55 μm-thick cured product layer against a 2 mm-thick polymethyl methacrylate sheet at a tensile speed of 300 mm / min using the 180° peel test method according to JIS Z 0237. Note that the above thickness (55 μm) is the thickness of the cured layer itself, which serves as a standard for objectively defining the adhesive strength of the cured layer according to the present invention, and it goes without saying that the curable organopolysiloxane composition of the present invention can be used as a cured layer or pressure-sensitive adhesive layer of any thickness, not limited to 55 μm.

[0081] [Use of the cured product] The cured product or semi-cured product of the present invention is slightly adhesive and can be used as an organopolysiloxane pressure-sensitive adhesive layer or an elastic pressure-sensitive adhesive material. Here, in order to improve the adhesion between the adherend and the pressure-sensitive adhesive layer, the surface of the pressure-sensitive adhesive layer or the substrate may be subjected to a surface treatment such as a primer treatment, a corona treatment, an etching treatment, or a plasma treatment.

[0082] The curable organopolysiloxane composition of the present invention can be coated on a release liner and cured by heating under the above-mentioned temperature conditions. The release liner can then be peeled off and the composition can be attached to a film-like, tape-like, or sheet-like substrate (hereinafter referred to as a "film-like substrate"). Alternatively, the composition can be coated on a film-like substrate and cured by heating under the above-mentioned temperature conditions to form a pressure-sensitive adhesive layer on the surface of the substrate. Laminates comprising a cured layer, particularly a film-like pressure-sensitive adhesive layer, formed on these film-like substrates by curing the organopolysiloxane composition of the present invention can be used for adhesive tapes, bandages, low-temperature supports, transfer films, labels, emblems, and decorative or explanatory signs. Furthermore, the cured layer formed by curing the organopolysiloxane composition of the present invention can be used in the assembly of automobile parts, toys, electronic circuits, or keyboards. 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.

[0083] Examples of substrates include paperboard, corrugated cardboard, clay-coated paper, polyolefin-laminated paper, particularly polyethylene-laminated paper, synthetic resin film / sheet, natural fiber cloth, synthetic fiber cloth, artificial leather cloth, and metal foil. Synthetic resin film / sheet is particularly preferred, and examples of synthetic resins include polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polycarbonate, polyethylene terephthalate, cyclopolyolefin, and nylon. When heat resistance is particularly required, films of heat-resistant synthetic resins such as polyimide, polyether ether ketone, polyethylene naphthalate (PEN), liquid crystal polyarylate, polyamide imide, and polyether sulfone are 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, polyethylene terephthalate, and PEN are preferred.

[0084] The substrate is preferably in the form of a film or sheet. There are no particular limitations on its thickness, and it can be designed to a desired thickness depending on the application. Furthermore, in order to improve the adhesion between the support film and the pressure-sensitive adhesive layer, a support film that has been subjected to a primer treatment, a corona treatment, an etching treatment, or a plasma treatment may be used. In addition, the surface opposite to the pressure-sensitive adhesive layer of the film substrate may be surface-treated, such as for scratch resistance, stain resistance, fingerprint resistance, anti-glare, anti-reflection, or anti-static treatment.

[0085] The pressure-sensitive adhesive layer according to the present invention may be a single layer or a multilayer formed by laminating two or more pressure-sensitive adhesive layers depending on the required properties. A multilayer pressure-sensitive adhesive layer may be formed by laminating pressure-sensitive adhesive films prepared one by one, or the step of applying the curable organopolysiloxane composition according to the present invention to a film substrate provided with a release layer and then curing the composition may be carried out multiple times.

[0086] The pressure-sensitive adhesive layer according to the present invention has adhesive or adhesive properties between members, and is therefore expected to function as an elastic pressure-sensitive adhesive member. Furthermore, the pressure-sensitive adhesive layer may also be given the role of another functional layer selected from a dielectric layer, a conductive layer, a heat-dissipating layer, an insulating layer, a reinforcing layer, etc. Furthermore, when the above-described curing reaction is carried out in multiple stages, and the change in adhesive strength that accompanies the change from a semi-cured product to a cured product is utilized, the pressure-sensitive adhesive layer may be used as an easily peelable temporary-fixing pressure-sensitive adhesive layer.

[0087] When the cured layer obtained by curing the curable organopolysiloxane composition of the present invention is a pressure-sensitive adhesive layer, particularly a pressure-sensitive adhesive / pressure-sensitive adhesive film, it is preferable to handle the cured layer as a laminate film releasably adhered to a film substrate equipped with a release layer having release coating properties. The release layer is also called a release liner, separator, release layer, or release coating layer. Preferably, it is a release layer having release coating properties such as a silicone-based release agent, a fluorine-based release agent, an alkyd-based release agent, or a fluorosilicone-based release agent, or it may be the substrate itself, which physically forms fine irregularities on the substrate surface or is difficult to adhere to the pressure-sensitive adhesive layer of the present invention. Furthermore, the laminate of the present invention may use a release layer obtained by curing a fluorosilicone-based release agent. The release layer in the laminate may be a differential release layer, i.e., a first release layer and a second release layer having different release agents and different release strengths, and the fluorosilicone-based release agent may be a curable, reactive silicone composition containing one or more fluorine-containing groups selected from a fluoroalkyl group and a perfluoropolyether group.

[0088] The cured product obtained by curing the curable organopolysiloxane composition of the present invention possesses both the above-mentioned viscoelasticity and slight adhesiveness, making it useful as an elastic adhesive member for various electronic devices or electrical devices. It is particularly useful as an electronic material, a display device member, or a transducer member (including sensors, speakers, actuators, and generators), and the cured product is preferably used as a member for electronic components or display devices. Because the cured product of the present invention has excellent transparency, a film-shaped cured product, particularly a substantially transparent pressure-sensitive adhesive film, is suitable as a member for display panels or displays, and is particularly useful for so-called touch panel applications in which devices, particularly electronic devices, can be operated by touching the screen with a fingertip or the like. The elastic adhesive layer of the present invention is particularly useful for film- or sheet-like components used in sensors, speakers, actuators, etc., where transparency is not required and a certain degree of stretchability or flexibility is required for the adhesive layer itself.

[0089] Furthermore, a pressure-sensitive adhesive layer obtained by curing a curable organopolysiloxane composition can be designed to be low-solvent or solvent-free, and can achieve pressure-sensitive adhesive properties that are weakly adhesive or easy to peel, thereby improving adhesion to substrates such as display devices, etc. Furthermore, if desired, by utilizing a semi-cured product or a multi-stage curing reaction, there is the advantage that it can be used as an easily peelable adhesive layer for the purpose of temporary fixing of display devices, semiconductors, etc., as a functional film (e.g., a protective film) that is used temporarily on the premise of being attached and detached.

[0090] [Use as an Adhesive Tape] An article comprising an adhesive layer obtained by curing the curable organopolysiloxane composition of the present invention may be an adhesive tape, particularly a protective tape intended to be attached and detached, and is characterized by comprising the above-mentioned adhesive layer and a sheet-like member made of a textile product such as the above-mentioned synthetic resin film / sheet, metal foil, woven fabric, nonwoven fabric, or paper. The type of such adhesive tape is not particularly limited, and examples include insulating tape, heat-resistant tape, solder masking tape, mica tape binder, temporary fixing tape (particularly including temporary fixing tape for silicone rubber parts, etc.), and splicing tape (particularly including splicing tape for silicone release paper).

[0091] [Adhesion Sheet] A laminate having a pressure-sensitive adhesive layer formed by curing the curable organopolysiloxane composition of the present invention may be formed on the above-mentioned film-like substrate, and preferably, these film-like substrates may be provided with a release layer for the cured adhesion layer.

[0092] In the laminate of the above-mentioned form, it is preferable that the sheet-like substrate has at least one release layer, and the release layer is in contact with the cured adhesive layer. This makes it possible to easily release the pressure-sensitive adhesive layer of the present invention from the sheet-like substrate. The release agent contained in the release layer is not particularly limited, and the same release agents as those mentioned above can be used.

[0093] In particular, the laminate may be capable of handling the pressure-sensitive adhesive layer separated from the film-like substrate alone, or may have two film-like substrates. Specifically, the laminate may comprise: a film-like substrate, a first release layer formed on the film-like substrate, a pressure-sensitive adhesive layer formed by coating the curable organopolysiloxane composition on the release layer and curing it, and a second release layer laminated on the pressure-sensitive adhesive layer.

[0094] Similarly, the laminate of the above form may be formed, for example, by applying the curable organopolysiloxane composition to one release layer formed on a film-like substrate and curing the composition to form a pressure-sensitive adhesive layer, and then laminating another release layer on the adhesive layer.

[0095] Preferably, the laminate of the above configuration can be produced by a production method including: Step (L1-I): applying the curable organopolysiloxane composition of the present invention to a film-like substrate that may optionally have a release layer; Step (L1-II): curing or semi-curing the curable organopolysiloxane composition applied in Step (L1-I) by one or more curing reactions selected from (i) a heat curing reaction and (ii) a photocuring reaction by irradiation with high-energy rays; and, optionally, Step (L1-III): laminating another substrate on the organopolysiloxane pressure-sensitive adhesive layer formed in Step (L1-II). Here, the first substrate used in Step (L1-I) is preferably a film-like substrate having a first release layer on its surface, and the other substrate used in Step (L2-III) is preferably a film-like substrate having a second release layer on its surface.

[0096] Alternatively, a laminate of the above form may be produced, for example, by sandwiching the curable silicone composition between a first film-like substrate and a second film-like substrate, forming the composition to a certain thickness with a press or roll while heating, and then curing the composition.

[0097] The first sheet substrate may have a first release layer, or the first sheet substrate itself may have release properties. Similarly, the second sheet substrate may have a second release layer, or the second sheet substrate itself may have release properties. When the first sheet substrate and / or the second sheet substrate have a first release layer and / or a second release layer, it is preferred that the cured adhesive layer contacts the first release layer and / or the second release layer.

[0098] Examples of sheet substrates having release properties include sheet substrates made of materials having release properties such as fluororesin films, and sheet substrates made of materials with no or low release properties such as polyolefin films to which release agents such as silicone, fluororesin, etc. On the other hand, examples of sheet substrates having a release layer include polyolefin films coated with release agents such as silicone, fluororesin, etc.

[0099] The laminate can be used, for example, by applying the cured adhesive layer to an adherend and then peeling the adhesive layer from the film-like substrate.

[0100] The thickness of the adhesive layer (cured adhesive layer) is preferably 5 to 10,000 μm, more preferably 10 μm or more or 8,000 μm or less, and even more preferably 20 μm or more or 5,000 μm or less.

[0101] [Semiconductors, Electronic Components, Batteries, Display Panels, or Display Members] The organopolysiloxane pressure-sensitive adhesive layer obtained by semi-curing the curable organopolysiloxane composition of the present invention can be used as a weakly adhesive adhesion layer in the production of laminates other than the above-mentioned peelable laminates. Specifically, the organopolysiloxane pressure-sensitive adhesive layer of the present invention can be used to protect, construct, and use electronic components such as semiconductors (including semiconductor precursors and integrated semiconductor devices such as LSIs and MEMS), semiconductor substrates (including flexible substrates and stretchable substrates such as wearable devices), batteries such as secondary batteries, and display panels or displays such as laminated touch screens or flat panel displays. The specific method of use can be any known method for adhesion layers (e.g., silicone PSAs, silicone adhesives, and silicone sealants) without any particular restrictions.

[0102] The method for producing a laminate such as a semiconductor is not particularly limited as long as an organopolysiloxane pressure-sensitive adhesive layer is used to bond components together, and an already cured or semi-cured organopolysiloxane pressure-sensitive adhesive layer may be used. For example, when producing a laminate such as a semiconductor, the release members on one or both sides of the organopolysiloxane pressure-sensitive adhesive layer of a laminate (for example, a single-sided or double-sided pressure-sensitive adhesive film) containing the organopolysiloxane pressure-sensitive adhesive layer described above may be peeled off, and a substrate on which a laminate such as a semiconductor is to be formed may be adhered to the exposed organopolysiloxane pressure-sensitive adhesive layer to form a laminate such as a semiconductor (including a precursor and temporary fixation for the purpose of protection in the process).

[0103] On the other hand, in the laminate of semiconductors or the like according to the present invention, the organopolysiloxane pressure-sensitive adhesive layer may be formed by applying an uncured curable organopolysiloxane composition onto or between substrates and then curing or semi-curing the composition.

[0104] For example, the laminate of the present invention can be obtained by a method for producing a laminate comprising: Step (L2A-I): applying the curable organopolysiloxane composition of the present invention to a first substrate; Step (L2A-II): curing or semi-curing the curable organopolysiloxane composition applied in Step (L2A-I) by one or more curing reactions selected from (i) a heat curing reaction and (ii) a photocuring reaction by irradiation with high-energy rays; and Step (L2A-III): laminating another substrate on the organopolysiloxane pressure-sensitive adhesive layer formed in Step (L2A-II). This method takes the form of forming an organopolysiloxane pressure-sensitive adhesive layer on one of the substrates, and then laminating another substrate on top of that.

[0105] Similarly, the laminate of the present invention can be obtained by a method for producing a laminate comprising: Step (L2B-I): applying the curable organopolysiloxane composition of the present invention to a first substrate; Step (L2B-II): laminating another substrate on the curable organopolysiloxane composition applied in Step (L2B-I); and Step (L2B-III): curing or semi-curing the uncured curable organopolysiloxane composition between the substrates using the laminate precursor formed in Step (L2B-II) through one or more curing reactions selected from (i) a heat curing reaction and (ii) a photocuring reaction by irradiation with high-energy rays. In this method, an uncured curable organopolysiloxane composition is placed between the substrates to be laminated, and the curable organopolysiloxane composition is subjected to a curing reaction to form an organopolysiloxane pressure-sensitive adhesive layer between the substrates.

[0106] Furthermore, when at least one of the substrates forming the laminate is a light-transmitting substrate, and the curable organopolysiloxane composition of the present invention contains (C1) a photoradical polymerization initiator and is photocurable by irradiation with high-energy rays, the laminate may be formed by irradiating high-energy rays through the light-transmitting substrate. When a plurality of light-transmitting substrates are present in the laminate, a laminate precursor having a plurality of uncured layers made of curable organopolysiloxane compositions therein may be prepared, such as "light-transmitting substrate / curable organopolysiloxane composition / light-transmitting substrate / curable organopolysiloxane composition...", and the interior of the laminate may be irradiated with high-energy rays through the light-transmitting substrate, thereby forming a plurality of organopolysiloxane pressure-sensitive adhesive layers within the laminate by a single irradiation of high-energy rays.

[0107] Specifically, the laminate of the present invention can be obtained by a method for producing a laminate, comprising the steps of: Step (L3-I): applying, to a substrate, the curable organopolysiloxane composition of the present invention, which is photocurable by irradiation with high-energy rays; Step (L3-II): laminating another substrate on the curable organopolysiloxane composition applied in Step (L3-I); and Step (L3-III): irradiating the laminate precursor formed in Step (L3-II) with high-energy rays that pass through the light-transmitting substrate, thereby curing or semi-curing the uncured curable organopolysiloxane composition between the substrates. This method is particularly suitable for forming an organopolysiloxane pressure-sensitive adhesive layer between substrates with low heat resistance, because it allows irradiation with high-energy rays that pass through the light-transmitting substrate. Furthermore, this method may be advantageous in industrial production efficiency, since it allows for the formation of a large number of laminates with low energy by first laminating the substrates together to form a laminate precursor, and then irradiating the laminate precursor with high-energy rays at a low temperature.

[0108] In these laminate manufacturing methods, the curing method may be selected from a heat curing reaction and a photocuring reaction depending on the curing reactivity of the curable organopolysiloxane, the intended use of the laminate, heat resistance, process requirements, etc., and the two curing reactions may be carried out simultaneously or in stages. Furthermore, when the organopolysiloxane pressure-sensitive adhesive layer in the laminate is in a semi-cured state, the laminate may be subjected to the same or different curing reaction to complete the curing reaction and convert the organopolysiloxane pressure-sensitive adhesive layer in the laminate into a completely cured state. That is, when the laminate contains an organopolysiloxane pressure-sensitive adhesive layer in a semi-cured state, the laminate manufacturing method according to the present invention may optionally further include a step of curing the organopolysiloxane pressure-sensitive adhesive layer in the semi-cured state by one or more curing reactions selected from (i) a heat curing reaction and (ii) a photocuring reaction by irradiation with high-energy rays.

[0109] [Display Panel or Display Member] As described above, the organopolysiloxane pressure-sensitive adhesive layer obtained by curing or semi-curing the curable organopolysiloxane composition of the present invention can be used in the construction and use of a laminated touch screen or flat panel display. For example, a cured product obtained by curing the curable organopolysiloxane composition of the present invention can be used in the manufacture of display devices such as touch panels as the optically transparent silicone-based pressure-sensitive adhesive film or pressure-sensitive adhesive layer disclosed in the aforementioned JP-T-2014-522436 or JP-T-2013-512326. Specifically, the organopolysiloxane pressure-sensitive adhesive layer of the present invention can be used, without particular limitation, as the pressure-sensitive adhesive layer or pressure-sensitive adhesive film described in JP-T-2013-512326.

[0110] 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 formed 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 the conductive layer. The substrate is preferably a sheet-like or film-like substrate, and examples thereof include 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 above-mentioned JP-A-2013-512326 and the like.

[0111] In addition, the organopolysiloxane pressure-sensitive adhesive layer according to the present invention may be used as an adhesive film for polarizing plates used in the manufacture of display devices such as touch panels, or as a pressure-sensitive adhesive layer used to bond a touch panel and a display module as described in JP 2013-065009 A.

[0112] The uses of the curable organopolysiloxane composition of the present invention and the cured product obtained by curing the same are not limited to those disclosed above, and organopolysiloxane pressure-sensitive adhesive layers comprising cured products obtained by curing the composition can be used in a variety of 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, dashboard displays for automobiles, etc., dashboard displays for various facilities, devices, and equipment, automatic ticket machines, automated teller machines, in-vehicle display devices, and in-vehicle transmission screens. The surface shape of such display devices may be curved rather than flat, and examples include various flat panel displays (FPDs) as well as curved displays or curved transmission screens used in automobiles (including electric vehicles) and aircraft, etc. Furthermore, these display devices can display on a screen or display icons for executing functions or programs, notification displays for emails and programs, and operation buttons for various devices such as car navigation systems, audio systems, and air conditioners, and may be equipped with a touch panel function that allows input operations by touching these icons, notification displays, and operation buttons with a finger. Examples of devices that can be used include CRT displays, liquid crystal displays, plasma displays, organic EL displays, inorganic EL displays, LED displays, surface electrolytic displays (SEDs), and field emission displays (FEDs), as well as touch panels using these displays. Furthermore, cured products obtained by curing the composition have excellent adhesiveness and viscoelastic properties and can be used as film or sheet-like members for transducers such as speaker membranes (including those for sensors, speakers, actuators, and generators), as well as sealing layers or adhesive layers for secondary batteries, fuel cells, or solar cell modules.

[0113] The organopolysiloxane pressure-sensitive adhesive layer according to the present invention has excellent transparency and excellent adhesion to substrates of various display devices, etc., and is therefore 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 equipped with a curved screen or curved display and optionally with a touch panel function. For example, JP 2017-047767 A, JP 2014-182335 A, JP 2014-063064 A, JP 2013-233852 A, etc. disclose vehicle display devices equipped with curved display surfaces, and the pressure-sensitive adhesive layer according to the present invention can be suitably used as or replace all or part of the adhesive layer or pressure-sensitive adhesive layer in these documents that requires transparency. Furthermore, it goes without saying that the curable organopolysiloxane composition of the present invention and its cured product can also be used in other known curved display devices to replace currently used adhesive or pressure-sensitive adhesive layers that require transparency, and it is preferable to adjust the design of the display device and the thickness of the components by known techniques in order to further utilize the advantages of the organopolysiloxane pressure-sensitive adhesive layer of the present invention.

[0114] The transparent film substrate provided with the organopolysiloxane pressure-sensitive adhesive layer of the present invention may be used for the purposes of preventing scratches, stains, fingerprints, static electricity, reflection, and peeping on the display surface.

[0115] EXAMPLES The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0116] Examples 1 to 10, Comparative Examples 1 to 4 Examples and Comparative Examples of the present invention are described below. In each Example, Comparative Example, and Reference Example, the term "cured" means that the composition was completely cured under the respective curing conditions.

[0117] (Preparation of Curable Silicone Compositions) Pressure-sensitive adhesive compositions comprising curable organopolysiloxane compositions shown in each Example and Comparative Example were prepared using the components shown in Table 1. Note that all percentages in the table are by mass. The viscosity and plasticity of each component were measured at 25°C. (A1) dimethylsiloxane / (5-hexenyl)methylsiloxane copolymer terminated at both ends by trimethylsiloxy groups, having a viscosity of 45 Pa s (vinyl group content: 0.83% by mass); (A2) dimethylsiloxane / methylvinylsiloxane copolymer crude rubber terminated at both ends by trimethylsiloxy groups, having a plasticity of 120 (vinyl group content: 0.84% ​​by mass); (A3) phenylmethylsiloxane polymer terminated at both ends by dimethylvinylsiloxy groups, having a viscosity of 40 Pa s (vinyl group content: 1.50% by mass); (B1-1) isobornyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.); (B1-2) dodecyl acrylate (=dodecyl acrylate) (manufactured by Tokyo Chemical Industry Co., Ltd.); (B1-3) trimethylolpropane triacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.); (B2-1) Dimethylsiloxane polymer capped at both ends with dimethyl(acryloyloxyoctyl)siloxy groups (C ３ H ３ O ２ Group content: 8.43% by mass) (C1-1) 2,4,6-trimethylbenzoyldiphenylphosphine oxide (product name: Omnirad TPO-L, manufactured by IGM Resins) (C1-2) 2-hydroxy-2-methylpropiophenone (manufactured by Tokyo Chemical Industry Co., Ltd.) (C2-1) Mixture of dibenzoyl peroxide, benzoyl-meta-methylbenzoyl peroxide, and meta-tolyl peroxide diluted with xylene (Niper BMT-K40, manufactured by NOF Corporation) (D) Xylene

[0118] (Siloxane mass % of composition) When the total mass % of component A relative to the total mass of the solids of each composition (components that form a cured product, excluding (D) organic solvent) is a and the combined mass % of component B2 is b, the siloxane mass % of the composition is defined as a + b2. Note that the compositions according to the present examples do not contain an organopolysiloxane resin component.

[0119] (Viscosity of Curable Composition) The viscosity (Pa·s) of the composition and each component at 25° C. was measured using a rotational viscometer (E-type viscometer VISCONIC EMD, manufactured by Tokimec Inc.).

[0120] (Measurement of adhesive strength of ultraviolet-curable adhesive) Each composition was applied to a PET film (manufactured by Toray, Lumirror (registered trademark) S10, thickness 50 μm) so that the thickness after curing would be 55 μm. After covering the composition with a release film (manufactured by Nippa, FSC-6, thickness 50 μm), a UV-LED ultraviolet irradiation device (manufactured by JATEC) was used to irradiate the adhesive from the PET film side with an ultraviolet ray irradiation amount (illuminance) of 4,000 mJ / cm2 as an integrated light amount. ２ The composition was cured by irradiating it with ultraviolet light having a wavelength of 365 nm. After leaving it for 1 hour, the sample was cut into a width of 25 mm, and the adhesive layer surface was attached to a SUS304BA plate (manufactured by Partec) and a PMMA plate (manufactured by Partec, Acrylite L001, 50 x 120 x 2 mm) using a roller to prepare test specimens. The adhesive strength (gf / 25 mm) of the test specimens was measured using the 180° peel test method according to JIS Z 0237 at a tensile speed of 300 mm / min, and is shown in Table 1.

[0121] (Measurement of Adhesion Strength of Thermosetting Pressure-Sensitive Adhesives) Each composition was coated onto a PET film (Toray, Lumirror (registered trademark) S10, 50 μm thick) to a cured thickness of 55 μm and cured at 130°C for 5 minutes. After leaving for 1 hour, the sample was cut into a width of 25 mm, and the adhesive layer surface was bonded to a SUS304BA plate (Partec) and a PMMA plate (Partec, Acrylite L001, 50 x 120 x 2 mm) using a roller to prepare test specimens. The adhesive strength (gf / 25 mm) of the test specimens measured at a tensile speed of 300 mm / min using the 180° peel test method according to JIS Z 0237 is shown in Table 1.

[0122] (Appearance Measurement of Cured Product) Two alkali-free glass plates (manufactured by Corning) were bonded together with each composition so that the thickness after curing was 200 μm. If the composition was uncured, it was cured after bonding to prepare a test piece. The haze value of the test piece was measured using a spectrophotometer CM-5 (manufactured by Konica Minolta). A haze value of less than 1 was classified as "Good", and a haze value of 1 or more was classified as "Poor".

[0123] As shown in Table 1, the compositions of the present invention according to Examples 1 to 4 have a viscosity that allows them to be applied without using an organic solvent, and can be easily cured with ultraviolet light. Furthermore, the composition of the present invention according to Example 5 has a viscosity that allows it to be applied and can be cured by heating, similar to conventional methods, by using an organic solvent. The cured product obtained by curing the composition had a clear, transparent appearance and practically low adhesiveness.

[0124] On the other hand, compositions with a silicone mass percentage of less than 50% lacked flexibility and only produced hard, brittle cured products, as in Comparative Example 1, making them unsuitable for practical use as adhesive layers, or, as in Comparative Example 2, the components were incompatible and cloudy, making it impossible to achieve a transparent, slightly adhesive layer.

Claims

1. (A) 50 to 99 parts by mass of a linear organopolysiloxane having two or more alkenyl groups in the molecule, (B) 0.1 to 49.9 parts by mass of one or more radical-reactive components selected from the following components (B1) and (B2): (B1) a monofunctional or polyfunctional vinyl monomer, and (B2) Organopolysiloxane compound having an organic group containing at least one acrylic or methacrylic group in the molecule (C) Radical polymerization initiator: 0.1 to 10 parts by mass wherein the sum of component (A) and component (B2) is 50 mass% or more based on the total mass of the solids of the composition.

2. 2. The curable organopolysiloxane composition according to claim 1, wherein the sum of components (A) and (B2) is in the range of 60 to 99.5 mass% based on the total mass of solids in the composition, and the mass ratio of the organopolysiloxane resin component to the sum of the masses of components (A) and (B2) is in the range of 0 to 0.

1.

3. 2. The curable organopolysiloxane composition according to claim 1, wherein at least a portion of component (B) is (B1-1) a vinyl monomer selected from (meth)acrylate compounds having 8 to 30 carbon atoms.

4. At least a part of the component (B) is attached to the terminal or side chain of the molecular chain of (B2-1). General formula (1): 【Chemical 1】 (In the formula, R １ are each independently a hydrogen atom, a methyl group, or a phenyl group, and Z is a divalent organic group which may contain a heteroatom and is bonded to a silicon atom constituting the main chain of the polysiloxane represented by *. A silicon atom-bonded functional group R represented by Ａ 2. The curable organopolysiloxane composition according to claim 1, which is a linear organopolysiloxane having at least one of the following:

5. 2. The curable organopolysiloxane composition according to claim 1, wherein at least a portion of component (B) is (B1-1-1) a vinyl monomer selected from the group consisting of dodecyl acrylate, isobornyl acrylate, and 2-ethylhexyl acrylate.

6. The curable organopolysiloxane composition according to claim 1, characterized in that the adhesive strength of a 55 μm thick cured product layer obtained by curing the composition to a 2 mm thick polymethyl methacrylate sheet is in the range of 5 to 50 gf / 25 mm, as measured using the 180° peel test method in accordance with JIS Z 0237 at a tensile speed of 300 mm / min.

7. 2. The curable organopolysiloxane composition according to claim 1, which is a solvent-free or low-solvent type.

8. 2. The curable organopolysiloxane composition according to claim 1, further comprising (D) an organic solvent in an amount of 0 to 100 parts by mass.

9. 2. The curable organopolysiloxane composition according to claim 1, wherein the viscosity of the entire composition at 25°C is in the range of 500 to 100,000 mPa·s.

10. 2. The curable organopolysiloxane composition according to claim 1, wherein at least a portion of component (C) is (C1) a photoradical polymerization initiator, and the composition is photocurable by irradiation with high-energy rays.

11. 2. The curable organopolysiloxane composition according to claim 1, wherein at least a portion of component (C) is a thermal radical polymerization initiator (C2), and the composition has heat-curing properties.

12. An organopolysiloxane pressure-sensitive adhesive layer obtained by curing or semi-curing the curable organopolysiloxane composition according to any one of claims 1 to 11.

13. An elastic pressure-sensitive adhesive member obtained by curing the curable organopolysiloxane composition according to any one of claims 1 to 11.

14. A laminate comprising a film-like substrate and an organopolysiloxane pressure-sensitive adhesive layer formed by curing or semi-curing the curable organopolysiloxane composition according to any one of claims 1 to 11.

15. The laminate according to claim 14, wherein one or more film-like substrates are provided with a release layer for the organopolysiloxane pressure-sensitive adhesive layer.

16. A laminate comprising at least two substrates and an organopolysiloxane pressure-sensitive adhesive layer formed by curing or semi-curing the curable organopolysiloxane composition according to any one of claims 1 to 11.

17. Step (L1-I): A step of applying the curable organopolysiloxane composition according to any one of claims 1 to 11 onto a film-like substrate which may optionally have a release layer; Step (L1-II): A step of curing or semi-curing the curable organopolysiloxane composition applied in Step (L1-I) by one or more curing reactions selected from (i) a heat curing reaction and (ii) a photocuring reaction by irradiation with high-energy rays. The method for producing a laminate according to claim 14, comprising at least

18. Process (L2A-I): A step of applying the curable organopolysiloxane composition according to any one of claims 1 to 11 onto a first substrate; Step (L2A-II): A step of curing or semi-curing the curable organopolysiloxane composition applied in Step (L2A-I) by one or more curing reactions selected from (i) a heat curing reaction and (ii) a photocuring reaction by irradiation with high-energy rays; and Step (L2A-III): A step of laminating another substrate on the organopolysiloxane pressure-sensitive adhesive layer formed in Step (L2A-2). The method for producing a laminate according to claim 16, comprising:

19. Process (L2B-I): A step of applying the curable organopolysiloxane composition according to any one of claims 1 to 11 onto a first substrate; Step (L2B-II): A step of further laminating another substrate on the curable organopolysiloxane composition applied in Step (L2B-I); and Step (L2B-III): A step of curing or semi-curing the uncured curable organopolysiloxane composition between the substrates by one or more curing reactions selected from (i) a heat curing reaction and (ii) a photocuring reaction by irradiation with high-energy rays, for the laminate precursor formed in Step (L2B-II). The method for producing a laminate according to claim 16, comprising:

20. At least one of the substrates forming the laminate is a light-transmitting substrate, Step (L3-I): A step of applying the curable organopolysiloxane composition photocurable by irradiation with high-energy rays according to claim 10 onto a substrate; Step (L3-II): A step of further laminating another substrate on the curable organopolysiloxane composition applied in Step (L3-I); Step (L3-III): A step of curing or semi-curing the uncured curable organopolysiloxane composition between the substrates by irradiating the laminate precursor formed in Step (L3-II) with high-energy rays transmitted through the light-transmitting substrate. The method for producing a laminate according to claim 16, comprising:

21. The method for producing a laminate according to any one of claims 18 to 20, further comprising, when a semi-cured organopolysiloxane pressure-sensitive adhesive layer is present in the laminate, a step of curing the semi-cured organopolysiloxane pressure-sensitive adhesive layer by one or more curing reactions selected from (i) a heat curing reaction and (ii) a photocuring reaction by irradiation with high-energy rays.

22. 22. The method for producing a laminate according to claim 21, wherein the adhesive strength of the organopolysiloxane pressure-sensitive adhesive layer to the substrate is changed by the step of curing the organopolysiloxane pressure-sensitive adhesive layer in a semi-cured state.

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