Laminate

Abstract

Provided is a laminate comprising a structure in which an organopolysiloxane-containing adhesive layer is disposed so as to face at least one peeling layer, wherein the peeling layer has a cured product obtained by curing a curable organopolysiloxane composition containing: (A) 100 parts by mass of a chain organopolysiloxane having a C2-12 alkenyl group, and either having a viscosity at 25°C of at least 1,000,000 mPa⋅s or having plasticity at 25°C; (B) 5-80 parts by mass of a chain organopolysiloxane having no alkenyl groups, and either having a viscosity at 25°C of at least 500,000 mPa⋅s or having plasticity at 25°C; (C) 0-20 parts by mass of a chain organopolysiloxane having no alkenyl groups and having a viscosity at 25°C of less than 500,000 mPa⋅s; (D) an organohydrogenpolysiloxane having two or more silicon-bonded hydrogen atoms (Si-H) per molecule; and (E) a hydrosilylation reaction catalyst.

Description

Laminate

[0001] The present invention relates to a laminate and an article. More specifically, the laminate has a structure in which a pressure-sensitive adhesive layer containing an organopolysiloxane is disposed opposite at least one release layer.

[0002] Silicone pressure-sensitive adhesives (pressure-sensitive adhesives) have excellent heat resistance, cold resistance, weather resistance, chemical resistance, and electrical insulation properties, and therefore have been widely used as pressure-sensitive adhesives for industrial protective tapes, masking tapes, and various functional medical tapes. Silicone pressure-sensitive adhesives have also recently been used in so-called assembly applications, such as bonding optical components for liquid crystal displays (display devices, functional films, lenses, and the like). Examples of such silicone pressure-sensitive adhesives include those described in Patent Documents 1 to 3. Patent Document 4 discloses a curable silicone composition containing a fluorine-containing compound.

[0003] Japanese Patent Application Laid-Open No. 61-162561 Japanese Patent Application Laid-Open No. 1-230669 Japanese Patent Application Laid-Open No. 6-93183 International Publication No. 2022 / 138349 Pamphlet

[0004] Under these circumstances, there has been a demand for new laminates and the like that have a cured product obtained by curing a curable organopolysiloxane composition.

[0005] The present invention provides the following laminate etc.: [1] A laminate having a structure in which a pressure-sensitive adhesive layer containing an organopolysiloxane is disposed opposite at least one release layer, the release layer comprising: (A) 100 parts by mass of a linear organopolysiloxane having an alkenyl group and having 2 to 12 carbon atoms, the linear organopolysiloxane having a viscosity of 1,000,000 mPa·s or more at 25°C or having a plasticity at 25°C, (B) 5 to 80 parts by mass of a linear organopolysiloxane having no alkenyl group, the linear organopolysiloxane having a viscosity of 500,000 mPa·s or more at 25°C or having a plasticity at 25°C, (C) 0 to 20 parts by mass of a linear organopolysiloxane having no alkenyl group, the linear organopolysiloxane having a viscosity of less than 500,000 mPa·s at 25°C, A laminate comprising a cured product obtained by curing a curable organopolysiloxane composition comprising: (D) an organohydrogenpolysiloxane having two or more silicon-bonded hydrogen atoms (Si—H) per molecule; and (E) a hydrosilylation reaction catalyst. [2] The laminate according to [1], wherein component (B) comprises a linear organopolysiloxane terminated at both molecular chain terminals with hydroxyl groups. [3] The laminate according to [1] or [2], wherein component (B) comprises a linear organopolysiloxane terminated at both molecular chain terminals with trialkylsilyl groups. [4] The laminate according to any one of [1] to [3], wherein component (C) comprises a linear organopolysiloxane terminated at both molecular chain terminals with trialkylsilyl groups or hydroxyl groups. [5] The laminate according to any one of [1] to [4], wherein component (C) comprises a linear organopolysiloxane having at least one group selected from the group consisting of an alkyl group and an aryl group having 1 to 12 carbon atoms in its side chain. [6] The laminate according to any one of [1] to [5], wherein component (C) comprises a linear organopolysiloxane having at least one group selected from the group consisting of a methyl group and a phenyl group in its side chain. [7] The laminate according to any one of [1] to [6], wherein component (D) comprises an organohydrogenpolysiloxane having a viscosity of 1 to 1,000 mPa s at 25°C and having both molecular chain terminals capped with trimethylsilyl groups.[8] The laminate according to any one of [1] to [7], wherein component (D) is contained in an amount such that the molar ratio of silicon-bonded hydrogen atoms in component (D) to alkenyl groups in component (A) is 0.5 to 10.0. [9] The laminate according to any one of [1] to [8], wherein component (A) comprises a linear organopolysiloxane having alkenyl groups having 2 to 12 carbon atoms in its side chain, component (B) comprises a linear organopolysiloxane whose molecular chain is terminally terminated with hydroxyl groups or whose molecular chain is terminally terminated with trimethylsilyl groups, and component (C) comprises a linear organopolysiloxane whose molecular chain is terminally terminated with trimethylsilyl groups or hydroxyl groups.

[10] The laminate according to any one of [1] to [9], wherein the laminate does not contain a fluorine-containing compound.

[11] The laminate according to any one of [1] to

[10] , which has a sheet, roll, or film shape.

[12] An article comprising the laminate according to any one of [1] to

[11] .

[0006] According to one aspect of the present invention, there is provided a laminate having a release layer (e.g., a release film; the same applies hereinafter) that can be peeled off with a low peel force and has reduced peel resistance to a silicone pressure-sensitive adhesive. According to one aspect of the present invention, there is provided a laminate having a release layer that has good residual adhesive strength even after peeling.

[0007] The upper and lower limit values ​​of the numerical ranges described herein can be arbitrarily combined. For example, when a numerical range is described as "preferably 30 to 100, more preferably 40 to 80," the ranges "30 to 80" and "40 to 100" are also included in the numerical ranges described herein. Furthermore, when a numerical range is described as "preferably 30 or more, more preferably 40 or more, and preferably 100 or less, more preferably 80 or less," the ranges "30 to 80" and "40 to 100" are also included in the numerical ranges described herein. In addition, when a numerical range described herein as "60 to 100," for example, means a range of "60 or more and 100 or less."

[0008] 1. Laminate One aspect of the present invention provides a laminate (hereinafter also referred to as "the laminate of the present invention"). The laminate of the present invention has a structure in which an organopolysiloxane-containing pressure-sensitive adhesive layer is disposed opposite at least one release layer, and the release layer comprises: (A) 100 parts by mass of a linear organopolysiloxane having an alkenyl group and having 2 to 12 carbon atoms, the linear organopolysiloxane having a viscosity of 1,000,000 mPa·s or more at 25°C or having a plasticity at 25°C; (B) 5 to 80 parts by mass of a linear organopolysiloxane having no alkenyl group, the linear organopolysiloxane having a viscosity of 500,000 mPa·s or more at 25°C or having a plasticity at 25°C; and optionally (C) a linear organopolysiloxane having no alkenyl group, the linear organopolysiloxane having a viscosity of less than 500,000 mPa·s at 25°C. The present invention has a cured product obtained by curing a curable organopolysiloxane composition (hereinafter also referred to as the "composition of the present invention") containing 0 to 20 parts by mass of (D) an organohydrogenpolysiloxane having two or more silicon-bonded hydrogen atoms (Si—H) per molecule, and (E) a hydrosilylation reaction catalyst. The laminate of one embodiment of the present invention does not contain a fluorine-containing compound. According to the laminate of one embodiment of the present invention, a laminate having a release layer with reduced peel resistance can be provided without using a fluorine-containing compound. Each component of the composition of the present invention that constitutes the release layer of the laminate of the present invention is described in detail below.

[0009] 1.1 Component (A) Component (A) is a linear organopolysiloxane with a high degree of polymerization that serves as a base polymer. The composition of the present invention contains, as component (A), a linear organopolysiloxane having an alkenyl group and 2 to 12 carbon atoms, which has a viscosity of 1,000,000 mPa·s or more at 25°C or has plasticity at 25°C. In one embodiment of the present invention, component (A) may be a mixture of linear organopolysiloxanes having the above properties. When a mixture of linear organopolysiloxanes is used as component (A), it is preferable that the mixture has the above properties. In one embodiment of the present invention, component (A) may continuously range from a high-viscosity liquid region (e.g., a viscosity of 1,000,000 mPa·s or more at 25°C) to a gum-like region having plasticity at 25°C, due to an increase in the degree of polymerization or the like. Generally, when the viscosity at 25°C exceeds 15,000,000 mPa s due to an increase in the degree of polymerization of the organopolysiloxane or other factors, it becomes difficult to measure the viscosity, and the viscosity transitions from a region exhibiting even higher viscosity (liquid state) to a region in which the physical properties are determined by plasticity (gummy state).

[0010] In one embodiment of the present invention, component (A) comprises an organopolysiloxane or a mixture thereof having a degree of polymerization or the like that allows viscosity measurement at 25° C. and that exhibits a liquid-like viscosity of 1,000,000 mPa s or more. Also, in another embodiment of the present invention, component (A) comprises an organopolysiloxane or a mixture thereof having a degree of polymerization or the like that allows viscosity measurement at 25° C. and that exhibits a gummy-like state whose physical properties should be determined by plasticity. Furthermore, in another embodiment of the present invention, component (A) comprises the above-described organopolysiloxane having a degree of polymerization or the like that exhibits a liquid-like state, and the above-described mixture of organopolysiloxanes having a degree of polymerization or the like that exhibits a gummy-like state.

[0011] The viscosity of the linear organopolysiloxane in component (A) at 25°C should be 1,000,000 mPa·s or higher, preferably 3,000,000 mPa·s or higher, more preferably 6,000,000 mPa·s or higher, even more preferably 9,000,000 mPa·s or higher, and particularly preferably 12,000,000 mPa·s or higher. The upper limit of the viscosity is not particularly limited, but examples include the range within which the viscosity can be measured at 25°C, specifically, 15,000,000 mPa·s or lower. By using a linear organopolysiloxane having a viscosity within the above range at 25°C, the peel resistance of the release layer formed by curing the composition of one embodiment of the present invention against adhesive substances can be reduced. In this specification, viscosity refers to a value measured at 25°C using a Brookfield viscometer.

[0012] The plasticity of the linear organopolysiloxane in component (A) at 25°C may be, specifically, 0.50 or more, preferably 1.00 or more, and particularly preferably 1.20 or more. The upper limit of the plasticity is not particularly limited, but may be, for example, 2.00 or less, 1.80 or less, or 1.70 or less. By using a linear organopolysiloxane having a plasticity at 25°C within the above range, the peel resistance of the release layer formed by curing the composition of one embodiment of the present invention can be reduced. Note that, in this specification, the plasticity is a value measured using a plasticity meter in accordance with the method specified in JIS K 6249. Specifically, it is the value (unit: mm) measured at 25°C when a load of 1 kgf is applied to a 4.2 g spherical sample for 3 minutes.

[0013] In one embodiment of the present invention, the alkenyl group having 2 to 12 carbon atoms specifically includes, for example, a vinyl group, a propenyl group (including an allyl group), a butenyl group, a pentenyl group, a hexenyl group, a heptenyl group, an octenyl group, a nonenyl group, a decenyl group, an undecenyl group, and a dodecenyl group. These groups also include structural isomers. In one embodiment of the present invention, the alkenyl group is preferably an alkenyl group having 2 to 10 carbon atoms, more preferably an alkenyl group having 2 to 8 carbon atoms, still more preferably a group selected from the group consisting of a vinyl group, an allyl group, and a hexenyl group, and particularly preferably a vinyl group or a hexenyl group.

[0014] The bonding position of the alkenyl group may be, for example, at the molecular chain terminal and / or at the molecular chain side chain, but it is preferable that component (A) has an alkenyl group bonded to a silicon atom at a site other than the molecular chain terminal. For example, by having an alkenyl group at the side chain, the release layer formed by curing the composition of one embodiment of the present invention can achieve good curability, release properties, and residual adhesive strength.

[0015] In one embodiment of the present invention, the vinyl (CH ２ The content of these (═CH—) moieties (hereinafter referred to as the “vinyl group content”) is preferably in the range of 0.005 to 5.0 mass %, more preferably 0.01 to 3.0 mass %, and even more preferably 0.10 to 1.5 mass %. By ensuring that the vinyl group content in component (A) falls within this range, it is possible to provide a curable organopolysiloxane composition that has good curability and residual adhesive strength, and is capable of forming a release layer with reduced peel resistance.

[0016] In component (A), the silicon-bonded group other than an alkenyl group may be a monovalent hydrocarbon group having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds. Specific examples of the monovalent hydrocarbon group having 1 to 12 carbon atoms and containing no aliphatic unsaturated bonds include alkyl groups, aryl groups, and aralkyl groups. Specific examples of the alkyl groups include methyl groups, ethyl groups, propyl groups such as n-propyl and isopropyl groups, butyl groups such as n-butyl, isobutyl, s-butyl, and t-butyl groups, pentyl groups, hexyl groups, heptyl groups, octyl groups, nonyl groups, decyl groups, undecyl groups, and dodecyl groups. These groups also include structural isomers. Specific examples of the aryl groups include phenyl groups, tolyl groups, xylyl groups, and naphthyl groups. Specific examples of the aralkyl groups include benzyl groups, phenethyl groups, 3-phenylpropyl groups, and 4-phenylbutyl groups. Among these, the monovalent hydrocarbon group is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and even more preferably a methyl group.

[0017] In one embodiment of the present invention, the linear organopolysiloxane of component (A) does not contain fluorine atoms.

[0018] The molecular structure of component (A) may be linear, partially branched linear, branched, cyclic, network, dendritic, or the like. In one embodiment of the present invention, component (A) may be a mixture of two or more of these molecular structures. In another embodiment of the present invention, component (A) may be one or more selected from the group consisting of linear organopolysiloxanes, branched organopolysiloxanes, and mixtures thereof. In another embodiment of the present invention, component (A) may be a linear organopolysiloxane.

[0019] Specific examples of linear organopolysiloxanes include dimethylsiloxane-methylvinylsiloxane copolymers capped at both molecular chain terminals with silanol groups, dimethylsiloxane-methylvinylsiloxane copolymers capped at both molecular chain terminals with trimethylsilyl groups, dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymers capped at both molecular chain terminals with trimethylsilyl groups, dimethylpolysiloxanes capped at both molecular chain terminals with dimethylvinylsiloxy groups, methylphenylpolysiloxanes capped at both molecular chain terminals with dimethylvinylsiloxy groups, dimethylsiloxane-methylvinylsiloxane copolymers capped at both molecular chain terminals with dimethylvinylsiloxy groups, dimethylpolysiloxane-methylphenylpolysiloxane copolymers capped at both molecular chain terminals with dimethylvinylsiloxy groups, dimethylsiloxane-methylvinylsiloxane copolymers capped at both molecular chain terminals with dimethylphenylsiloxy groups, and dimethylpolysiloxanes capped at both molecular chain terminals with methylvinylphenylsiloxy groups. In addition to the above, linear organopolysiloxanes include dimethylsiloxane-methylhexenylsiloxane copolymers capped at both molecular chain ends with silanol groups, dimethylsiloxane-methylhexenylsiloxane copolymers capped at both molecular chain ends with trimethylsilyl groups, dimethylsiloxane-methylhexenylsiloxane-methylphenylsiloxane copolymers capped at both molecular chain ends with trimethylsilyl groups, dimethylpolysiloxane capped at both molecular chain ends with dimethylhexenylsiloxy groups, and dimethylhexenylsiloxane copolymers capped at both molecular chain ends with dimethylhexenylsiloxy groups. These include methylphenylpolysiloxanes capped with dimethylsiloxy groups, dimethylsiloxane-methylhexenylsiloxane copolymers capped at both molecular chain ends with dimethylhexenylsiloxy groups, dimethylpolysiloxane-methylphenylpolysiloxane copolymers capped at both molecular chain ends with dimethylhexenylsiloxy groups, dimethylsiloxane-methylhexenylsiloxane copolymers capped at both molecular chain ends with dimethylphenylsiloxy groups, and dimethylpolysiloxanes capped at both molecular chain ends with methylhexenylphenylsiloxy groups.

[0020] Branched organopolysiloxanes include, for example, MQ resins, MDQ resins, MTQ resins, MDTQ resins, TD resins, TQ resins, and TDQ resins, which are composed of any combination of triorganosiloxy units (M units) (organo groups are methyl groups only, or groups selected from methyl groups, vinyl groups, and phenyl groups), diorganosiloxy units (D units) (organo groups are methyl groups only, or groups selected from methyl groups, vinyl groups, and phenyl groups), monoorganosiloxy units (T units) (organo groups are methyl groups, vinyl groups, or phenyl groups), and siloxy units (Q units).

[0021] In one embodiment of the present invention, the content of component (A) is not particularly limited. In the composition of the present invention, by adjusting the content of each component described below based on 100 parts by mass of component (A), it is possible to simultaneously maintain good release properties and residual adhesive strength of the release layer formed from the composition of one embodiment of the present invention.

[0022] 1.2 Component (B) Component (B) is a linear organopolysiloxane. The inclusion of component (B) can reduce the peel resistance of the release layer formed by curing the composition of one embodiment of the present invention. The composition of the present invention contains, as component (B), a linear organopolysiloxane having no alkenyl groups and having a viscosity at 25°C of 500,000 mPa·s or more or a plasticity at 25°C. In one embodiment of the present invention, component (B) may be a mixture of linear organopolysiloxanes having the above properties. When a mixture of linear organopolysiloxanes is used as component (B), it is preferable that the mixture has the above properties.

[0023] The viscosity of the linear organopolysiloxane in component (B) at 25°C needs only to be 500,000 mPa·s or higher, preferably 1,000,000 mPa·s or higher, more preferably 3,000,000 mPa·s or higher, even more preferably 6,000,000 mPa·s or higher, and particularly preferably 12,000,000 mPa·s or higher. The upper limit of the viscosity is not particularly limited, but examples include the range in which the viscosity can be measured at 25°C, and specifically, 15,000,000 mPa·s or lower. By using a linear organopolysiloxane having a viscosity at 25°C within the above range together with component (A), the peel resistance of the release layer formed by curing the composition of one embodiment of the present invention against adhesive substances can be reduced.

[0024] The plasticity of the linear organopolysiloxane in component (B) at 25°C may specifically be 0.50 or more, preferably 1.00 or more, and particularly preferably 1.20 or more. The upper limit of the plasticity is not particularly limited, but may be, for example, 2.00 or less, 1.80 or less, or 1.70 or less. By using a linear organopolysiloxane having a plasticity at 25°C within the above range together with component (A), it is possible to reduce the peel resistance of the release layer formed by curing the composition of one embodiment of the present invention.

[0025] In the composition of the present invention, component (B) does not have an alkenyl group in the molecule. In one embodiment of the present invention, component (B) does not have an alkenyl group at the molecular chain terminal or in a molecular chain side chain. When component (B) does not have an alkenyl group in the molecule, the peel resistance of the release layer formed by curing the composition of one embodiment of the present invention against adhesive substances can be reduced.

[0026] In one embodiment of the present invention, the linear organopolysiloxane of component (B) does not contain fluorine atoms.

[0027] The molecular structure of component (B) may be linear, partially branched linear, branched, cyclic, network, dendritic, or the like. In one embodiment of the present invention, component (B) may be a mixture of two or more of these molecular structures. In another embodiment of the present invention, component (B) may be one or more selected from the group consisting of linear organopolysiloxanes, branched organopolysiloxanes, and mixtures thereof. In another embodiment of the present invention, component (B) may be a linear organopolysiloxane.

[0028] Component (B) in one embodiment of the present invention comprises a linear organopolysiloxane whose molecular chain ends are capped with hydroxyl groups. Component (B) in one embodiment of the present invention comprises a linear organopolysiloxane whose molecular chain ends are capped with trialkylsilyl groups. The alkyl groups constituting the trialkylsilyl groups are as described below. Component (B) in one embodiment of the present invention comprises a mixture of a linear organopolysiloxane whose molecular chain ends are capped with hydroxyl groups and a linear organopolysiloxane whose molecular chain ends are capped with trialkylsilyl groups. The alkyl group constituting the trialkylsilyl group may be an alkyl group having 1 to 12 carbon atoms, and specifically includes, for example, methyl, ethyl, propyl groups such as n-propyl and isopropyl, butyl groups such as n-butyl, isobutyl, s-butyl and t-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl groups. These groups also include structural isomers. Among these, alkyl groups having 1 to 6 carbon atoms are preferred, alkyl groups having 1 to 4 carbon atoms are more preferred, and methyl groups are even more preferred.

[0029] Specific examples of linear organopolysiloxanes include dimethylpolysiloxanes capped at both molecular chain terminals with silanol groups, methylphenylpolysiloxanes capped at both molecular chain terminals with silanol groups, dimethylpolysiloxane-methylphenylpolysiloxane copolymers capped at both molecular chain terminals with silanol groups, dimethylsiloxanes capped at both molecular chain terminals with trimethylsilyl groups, dimethylpolysiloxanes capped at both molecular chain terminals with trimethylsilyl groups, methylphenylpolysiloxanes capped at both molecular chain terminals with trimethylsilyl groups, and dimethylpolysiloxane-methylphenylpolysiloxane copolymers capped at both molecular chain terminals with trimethylsilyl groups.

[0030] Branched organopolysiloxanes include, for example, MQ resins, MDQ resins, MTQ resins, MDTQ resins, TD resins, TQ resins, and TDQ resins, which are composed of any combination of triorganosiloxy units (M units) (organo groups are methyl groups only, or groups selected from methyl groups, vinyl groups, and phenyl groups), diorganosiloxy units (D units) (organo groups are methyl groups only, or groups selected from methyl groups, vinyl groups, and phenyl groups), monoorganosiloxy units (T units) (organo groups are methyl groups or phenyl groups), and siloxy units (Q units).

[0031] In the composition of the present invention, the content of component (B) is 5 to 80 parts by mass based on 100 parts by mass of component (A). In one embodiment of the present invention, the content of component (B) is more preferably in the range of 7 to 70 parts by mass, even more preferably in the range of 8 to 60 parts by mass, and particularly preferably in the range of 9 to 55 parts by mass based on 100 parts by mass of component (A). By adjusting the content of component (B) within the above range, it is possible to maintain both good release properties and residual adhesive strength of the release layer formed by curing the composition of one embodiment of the present invention.

[0032] 1.3 Component (C) Component (C) is a component that can control the release properties of the release layer formed from the composition of one embodiment of the present invention and is a component that may be optionally contained in the composition of one embodiment of the present invention. The inclusion of component (C) can stabilize the release resistance. The composition of one embodiment of the present invention contains, as component (C), a linear organopolysiloxane having no alkenyl groups and having a viscosity at 25°C of less than 500,000 mPa·s. In one embodiment of the present invention, component (C) may be a mixture of linear organopolysiloxanes having the above-described properties. When a mixture of linear organopolysiloxanes is used as component (C), it is preferable that the mixture has the above-described properties.

[0033] The viscosity of the linear organopolysiloxane in component (C) at 25°C may be less than 500,000 mPa s, but is preferably 250,000 mPa s or less, more preferably 100,000 mPa s or less, and even more preferably 50,000 mPa s or less. The lower limit of the viscosity is not particularly limited, but may be, for example, 10 mPa s or more, 100 mPa s or more, 300 mPa s or more, or 500 mPa s or more. By using a linear organopolysiloxane whose viscosity at 25°C is within the above range, the release behavior of the release layer formed from the composition of one embodiment of the present invention can be stabilized.

[0034] In the composition of the present invention, component (C) does not have an alkenyl group in the molecule. In one embodiment of the present invention, component (C) does not have an alkenyl group at the molecular chain terminal or in a molecular chain side chain. By not having an alkenyl group in the molecule of component (C), peel resistance against adhesive substances can be stabilized.

[0035] In one embodiment of the present invention, the linear organopolysiloxane of component (C) does not contain fluorine atoms.

[0036] The molecular structure of component (C) may be linear, partially branched linear, branched, cyclic, network, dendritic, or the like. In one embodiment of the present invention, component (C) may be a mixture of two or more of these molecular structures. In another embodiment of the present invention, component (C) may be one or more selected from the group consisting of linear organopolysiloxanes, branched organopolysiloxanes, and mixtures thereof. In another embodiment of the present invention, component (C) may be a linear organopolysiloxane.

[0037] Component (C) of one embodiment of the present invention comprises a linear organopolysiloxane terminally terminated with hydroxyl groups. Component (C) of one embodiment of the present invention comprises a linear organopolysiloxane terminally terminated with trialkylsilyl groups. Component (C) of one embodiment of the present invention comprises a mixture of a linear organopolysiloxane terminally terminated with hydroxyl groups and a linear organopolysiloxane terminally terminated with trialkylsilyl groups. The alkyl groups constituting the trialkylsilyl groups may be the same as those listed above in "1.2 Component (B)."

[0038] Component (C) in one embodiment of the present invention comprises a linear organopolysiloxane having at least one group selected from the group consisting of alkyl groups and aryl groups having 1 to 12 carbon atoms in its side chain. Component (C) in one embodiment of the present invention comprises a linear organopolysiloxane whose molecular chain is terminally capped with hydroxyl groups or trialkylsilyl groups and which has at least one group selected from the group consisting of alkyl groups and aryl groups having 1 to 12 carbon atoms in its side chain. The side chain is preferably an alkyl group or a phenyl group having 1 to 6 carbon atoms, and more preferably a methyl group or a phenyl group.

[0039] Specific examples of linear organopolysiloxanes include dimethylpolysiloxanes capped at both molecular chain terminals with silanol groups, methylphenylpolysiloxanes capped at both molecular chain terminals with silanol groups, dimethylpolysiloxane-methylphenylpolysiloxane copolymers capped at both molecular chain terminals with silanol groups, dimethylsiloxanes capped at both molecular chain terminals with trimethylsilyl groups, dimethylpolysiloxanes capped at both molecular chain terminals with trimethylsilyl groups, methylphenylpolysiloxanes capped at both molecular chain terminals with trimethylsilyl groups, and dimethylpolysiloxane-methylphenylpolysiloxane copolymers capped at both molecular chain terminals with trimethylsilyl groups.

[0040] Branched organopolysiloxanes include, for example, MQ resins, MDQ resins, MTQ resins, MDTQ resins, TD resins, TQ resins, and TDQ resins, which are composed of any combination of triorganosiloxy units (M units) (organo groups are methyl groups only, or groups selected from methyl groups, vinyl groups, and phenyl groups), diorganosiloxy units (D units) (organo groups are methyl groups only, or groups selected from methyl groups, vinyl groups, and phenyl groups), monoorganosiloxy units (T units) (organo groups are methyl groups or phenyl groups), and siloxy units (Q units).

[0041] In the composition of the present invention, the content of component (C) is 0 to 20 parts by mass, based on 100 parts by mass of component (A). In one embodiment of the present invention, the content of component (C) is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, even more preferably 1.0 to 5.0 parts by mass, and particularly preferably 1.2 to 2.0 parts by mass, based on 100 parts by mass of component (A). When component (C) is contained, by adjusting the content of component (C) within the above range, the curing reaction of the composition is not inhibited, and good adhesive strength is maintained, while the release layer formed by curing the composition of one embodiment of the present invention can simultaneously maintain good release properties and residual adhesive strength.

[0042] A composition according to one embodiment of the present invention comprises a curable organopolysiloxane composition having a combination of the following components (A) to (C): component (A) comprises a linear organopolysiloxane having a C2 to C12 alkenyl group in the side chain, component (B) comprises a linear organopolysiloxane the molecular chain of which is terminally terminated with hydroxyl groups or terminally terminated with trimethylsilyl groups, and component (C) comprises a linear organopolysiloxane the molecular chain of which is terminally terminated with trimethylsilyl groups or hydroxyl groups.

[0043] 1.4 Component (D) Component (D) is a component that functions as a crosslinking agent. The composition of the present invention contains an organohydrogenpolysiloxane having two or more silicon-bonded hydrogen atoms (Si—H) per molecule. In one embodiment of the present invention, component (D) may have three or more silicon-bonded hydrogen atoms (Si—H) per molecule. The bonding positions of the hydrogen atoms in the molecule are not particularly limited. The number of silicon-bonded hydrogen atoms per molecule is the average value for all molecules.

[0044] In component (D), the silicon-bonded group other than a hydrogen atom may be a monovalent hydrocarbon group having 1 to 12 carbon atoms that does not contain an aliphatic unsaturated bond. Examples of such monovalent hydrocarbon groups include the same groups as those listed above in "1.1 Component (A)." Furthermore, such monovalent hydrocarbon groups are preferably alkyl groups having 1 to 6 carbon atoms, more preferably alkyl groups having 1 to 4 carbon atoms, and even more preferably methyl groups.

[0045] The molecular structure of component (D) may be linear, partially branched linear, branched, cyclic, network, dendritic, or the like. In one embodiment of the present invention, component (D) may be a mixture of two or more of these molecular structures, and in particular may be a mixture of two or more organohydrogenpolysiloxanes differing in viscosity or molecular structure. In another embodiment of the present invention, component (D) may be one or more selected from the group consisting of linear organohydrogenpolysiloxanes, branched organohydrogenpolysiloxanes, and mixtures thereof. In another embodiment of the present invention, component (D) may be a linear organohydrogenpolysiloxane.

[0046] In one embodiment of the present invention, the viscosity of component (D) at 25°C is preferably in the range of 1 to 1,000 mPa·s, more preferably 2 to 300 mPa·s, and even more preferably 5 to 100 mPa·s. In one embodiment of the present invention, component (D) may be a mixture of two or more different organohydrogenpolysiloxanes. Furthermore, when a mixture of organohydrogenpolysiloxanes is used as component (D), for example, the viscosities at 25°C of two components (d-1) and (d-2) differing in viscosity and / or structure may each be in the following numerical ranges. That is, in one embodiment of the present invention, the viscosity of component (d-1) at 25°C is preferably 5 to 35 mPa·s, more preferably 10 to 30 mPa·s, and even more preferably 15 to 25 mPa·s. In one embodiment of the present invention, the viscosity of component (d-2) at 25°C is preferably 40 to 1,000 mPa·s, more preferably 45 to 500 mPa·s, and even more preferably 50 to 300 mPa·s. Similarly, a chain (particularly linear) organohydrogenpolysiloxane may be selected as component (d-1), and a resinous organohydrogenpolysiloxane (e.g., one having branched siloxane units such as T units and Q units) may be used as component (d-2). Furthermore, two or more types of resinous organohydrogenpolysiloxanes differing in viscosity and content of silicon-bonded hydrogen atoms may be used in combination as components (d-1) and (d-2). The content ratio of component (d-1) to component (d-2) may be any value that results in a viscosity of the mixture within the above range, and specifically, for example, is 90:10 to 10:90, preferably 80:20 to 20:80, more preferably 60:40 to 40:60, and even more preferably 50:50. By using a mixture of two or more organohydrogenpolysiloxanes having different viscosities or chemical structures, it is possible to adjust the curability and adhesion to the substrate.

[0047] In one embodiment of the present invention, the content of component (D) may be an amount such that the molar ratio of silicon-bonded hydrogen atoms in component (D) to alkenyl groups in component (A) (SiH / Vi) is 0.5 to 10.0. The content of component (D) is an amount such that this molar ratio is preferably 0.7 to 8.0, more preferably 0.8 to 5.0, and even more preferably 0.8 to 3.0. By adjusting this molar ratio within the above range, it is possible to reduce the peel resistance of a release film formed from the composition of one embodiment of the present invention while maintaining the curability of the composition.

[0048] Specific examples of component (D) include dimethylsiloxane-methylhydrogensiloxane copolymers capped at both molecular chain terminals with trimethylsilyl groups, dimethylsiloxane-methylhydrogensiloxane copolymers capped at both molecular chain terminals with dimethylhydrogensiloxy groups, dimethylpolysiloxanes capped at both molecular chain terminals with dimethylhydrogensiloxy groups, methylhydrogenpolysiloxanes capped at both molecular chain terminals with trimethylsilyl groups, cyclic methylhydrogenpolysiloxanes, and cyclic methylhydrogensiloxane-dimethylsiloxane copolymers. Component (D) preferably has a viscosity at 25°C within the above-mentioned range and includes an organohydrogenpolysiloxane capped at both molecular chain terminals with trimethylsilyl groups.

[0049] 1.5 Component (E) Component (E) is a component for accelerating the hydrosilylation reaction and curing the composition of the present invention. Specific examples of hydrosilylation reaction catalysts include platinum-based catalysts, rhodium-based catalysts, and palladium-based catalysts. Among these, platinum-based catalysts are preferred because they can significantly accelerate curing. Specific examples of the platinum-based catalyst include platinum fine powder, chloroplatinic acid, alcohol solutions of chloroplatinic acid, platinum-alkenylsiloxane complexes, platinum-olefin complexes, platinum-carbonyl complexes, and catalysts in which these platinum-based catalysts are dispersed or encapsulated in thermoplastic resins such as silicone resins, polycarbonate resins, and acrylic resins. Among these, platinum-alkenylsiloxane complexes are preferred. The alkenylsiloxane may be 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, alkenylsiloxanes in which a portion of the methyl groups of these alkenylsiloxanes have been substituted with ethyl groups, phenyl groups, or the like, or alkenylsiloxanes in which the vinyl groups of these alkenylsiloxanes have been substituted with allyl groups, hexenyl groups, or the like. 1,3-divinyl-1,1,3,3-tetramethyldisiloxane is particularly preferred because of the good stability of the platinum-alkenylsiloxane complex. Catalysts that promote the hydrosilylation reaction also include non-platinum metal catalysts such as iron, ruthenium, and iron / cobalt.

[0050] The hydrosilylation catalyst may also be a high-energy ray-activated catalyst (also called a photoactivated catalyst) that promotes the hydrosilylation reaction upon irradiation with high-energy rays such as ultraviolet rays. Examples of high-energy rays include ultraviolet rays, gamma rays, X-rays, alpha rays, and electron beams. Specific examples of the high energy ray activated catalyst include (methylcyclopentadienyl)trimethylplatinum(IV), (cyclopentadienyl)trimethylplatinum(IV), (1,2,3,4,5-pentamethylcyclopentadienyl)trimethylplatinum(IV), (cyclopentadienyl)dimethylethylplatinum(IV), (cyclopentadienyl)dimethylacetylplatinum(IV), (trimethylsilylcyclopentadienyl)trimethylplatinum(IV), (methoxycarbonylcyclopentadienyl)trimethylplatinum(IV), (dimethylphenylsilylcyclopentadienyl)trimethylcyclopentadienylplatinum(IV), trimethyl(acetylacetonato)platinum(IV), trimethyl(3,5-heptanedionato) ... Examples of the platinum (II) bis(2,4-pentanedionato)platinum(II), bis(2,4-hexanedionato)platinum(II), bis(2,4-heptanedionato)platinum(II), bis(3,5-heptanedionato)platinum(II), bis(1-phenyl-1,3-butanedionato)platinum(II), bis(1,3-diphenyl-1,3-propanedionato)platinum(II), and bis(hexafluoroacetylacetonato)platinum(II) are also included. Component (E) may be any of the above, and may be used alone or in combination of two or more.

[0051] In one embodiment of the present invention, the content of component (E) is preferably in the range of 1.0 to 1,000 ppm by mass, more preferably 10 to 500 ppm by mass, and even more preferably 100 to 300 ppm by mass, in terms of the amount of metal atoms, relative to the total amount of components (A), (B), (C), and (D).

[0052] 1.6 Component (F) Component (F) is an organic solvent that may be used optionally to dissolve the linear organopolysiloxane of component (A) uniformly and to dissolve the entire composition. "Dissolved" here means that a homogeneous, transparent liquid is obtained that is not turbid at 25°C. Addition of an organic solvent reduces the viscosity of the composition of one embodiment of the present invention, improving its ease of application and wettability to substrates.

[0053] Examples of the component (F) include aromatic hydrocarbon solvents such as toluene and xylene; aliphatic hydrocarbon solvents such as hexane, heptane, octane, isooctane, decane, cyclohexane, methylcyclohexane, and isoparaffin; hydrocarbon solvents such as industrial gasoline (rubber volatile oil, etc.), petroleum benzine, and solvent naphtha; ketone solvents such as acetone, methyl ethyl ketone, 2-pentanone, 3-pentanone, 2-hexanone, 2-heptanone, 4-heptanone, methyl isobutyl ketone, diisobutyl ketone, acetonylacetone, and cyclohexanone; and ethyl acetate. Examples of suitable solvents include ester-based solvents such as propylene glycol monomethyl ether acetate, propyl acetate, isopropyl acetate, butyl acetate, and isobutyl acetate; solvents having an ester and an ether moiety such as 2-methoxyethyl acetate, 2-ethoxyethyl acetate, propylene glycol monomethyl ether acetate, and 2-butoxyethyl acetate; and siloxane-based solvents such as hexamethyldisiloxane, octamethyltrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, tris(trimethylsilyl)methylsilane, and tetrakis(trimethylsilyl)silane. Furthermore, examples of suitable solvents that may be used as component (F) include diethyl ether, dipropyl ether, diisopropyl ether, dibutyl ether, diisobutyl ether, di-sec-butyl ether, di-tert-butyl ether, methyl tert-butyl ether, ethyl tert-butyl ether, and pentane. The above-mentioned solvents may be used alone or in combination of two or more.

[0054] In one embodiment of the present invention, the content of component (F) when used is not particularly limited as long as it is an amount that allows component (A) or the entire composition to be uniformly dissolved in the component (F). For example, the content is 10,000 parts by mass or less, and preferably in the range of 20 to 5,000 parts by mass, per 100 parts by mass of component (A).

[0055] 1.7 Component (G) Component (G) is a hydrosilylation reaction inhibitor that may be optionally used to inhibit the crosslinking reaction of the composition of one embodiment of the present invention. Specific examples of component (G) include alkyne alcohols such as 1-ethynylcyclohexane-1-ol, 3-methyl-1-butyn-3-ol, 2-methyl-3-butyn-2-ol, 3,5-dimethyl-1-hexyn-3-ol, and 2-phenyl-3-butyn-2-ol; eneyne compounds such as 3-methyl-3-penten-1-yne and 3,5-dimethyl-3-hexen-1-yne; methylalkenylsiloxane oligomers such as 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane and 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane; Alkyneoxysilanes such as dimethylbis(3-methyl-1-butyn-3-oxy)silane and methylvinylbis(3-methyl-1-butyn-3-oxy)silane; alkyneoxysilane compounds such as methyltris(1-methyl-1-phenyl-propynoxy)silane, dimethylbis(1-methyl-1-phenyl-propynoxy)silane, methyltris(1,1-dimethyl-propynoxy)silane and dimethylbis(1,1-dimethyl-propynoxy)silane; and others include benzotriazole; diallyl maleate, diallyl fumarate, and (tris((1,1-dimethyl-2-propynyl)oxy)methylsilane. As component (G), the above-mentioned compounds may be used alone or in combination of two or more.

[0056] In one embodiment of the present invention, the content of component (G) when used is not particularly limited as long as it is an amount that provides a sufficient pot life to the composition of one embodiment of the present invention. For example, the content is preferably in the range of 0.01 to 5 parts by mass, 0.05 to 5 parts by mass, or 0.05 to 3 parts by mass per 100 parts by mass of component (A).

[0057] 1.8 Optional Components In addition to components (A) to (E) and optional components (F) to (G), the composition of one embodiment of the present invention may further contain other components as needed. Examples of such optional components include photopolymerization initiators, antioxidants, reactive diluents, leveling agents, fillers, antistatic agents, antifoaming agents, and pigments. The type of antistatic agent is not particularly limited, and antistatic agents such as conductive fine particles such as carbon black, ionic conductive antistatic agents as described in JP 2009-030028 A, lithium salts as described in JP 2012-157978 A, cationic surfactants, anionic surfactants, and nonionic surfactants can be used without particular limitation. For example, the incorporation of an antistatic agent is preferred for use in protective films for electronic devices such as displays.

[0058] 1.9 Method for Producing the Composition of the Present Invention The composition of the present invention can be produced by uniformly mixing components (A) to (E), optional components (F) to (G), and other optional components. The order of addition of the components is not particularly limited. In one embodiment, if the composition obtained after mixing the components is not to be used immediately, the mixture of components (A) to (D) and component (E) may be stored separately and then mixed immediately before use. Furthermore, in a composition containing other components such as components (A) to (E) and optional component (F), the type and amount of the hydrosilylation reaction inhibitor in component (G) may be adjusted to produce a composition that does not crosslink at room temperature but crosslinks and cures upon heating.

[0059] 1.10 Method for Curing the Composition of the Present Invention The composition of the present invention can be cured by known methods. For example, a release layer (cured release layer) made of a cured silicone coating (cured organopolysiloxane coating) can be formed on the surface of the substrate by uniformly applying a composition of one embodiment of the present invention to a sheet-like or film-like substrate and then heating, irradiating with high-energy rays (e.g., ultraviolet rays, electron beams, etc.), or a combination of these, under conditions sufficient to crosslink components (A) to (D) via a hydrosilylation reaction.

[0060] 2. Other Configurations of the Laminate The laminate of the present invention contains an organopolysiloxane as the adhesive layer. The organopolysiloxane is not limited to a specific one, and any suitable organopolysiloxane can be used for the intended application of the laminate (e.g., adhesive tape). The curing mechanism of the silicone adhesive is not particularly limited, and hydrosilylation-curable, peroxide-curable, photocurable, or other suitable adhesives can be used. Commercially available silicone adhesive compositions can be used. For example, hydrosilylation-curable silicone adhesives such as SD 4580 PSA, SD 4584 PSA, SD 4585 PSA, and SH 4280 PSA manufactured by Dow-Toray Industries, Inc. can be used. Furthermore, in assembly applications, particularly OCA applications, high adhesive strength and high flexibility may be required over a wide temperature range, including low temperatures. For this reason, it is preferable to use a silicone pressure-sensitive adhesive composition that can be designed so that the cured pressure-sensitive adhesive composition has a low glass transition temperature, for example, at or below room temperature, and that has a low storage modulus at low temperatures and a sufficiently large elongation at break. Examples include the silicone pressure-sensitive adhesive composition proposed by the present applicant in WO 2017 / 188308 and the like.

[0061] In the laminate of one embodiment of the present invention, the thickness of the pressure-sensitive adhesive layer is not particularly limited, but is preferably 0.1 to 300 μm, and more preferably 0.5 to 200 μm. The thickness of the release layer is also not particularly limited, but is preferably 2.0 μm or less, 1.0 μm or less, 0.5 μm or less, 0.4 μm or less, or 0.3 μm or less. The thickness of the release layer is preferably 0.01 μm or more, 0.05 μm or more, or 0.1 μm or more. When the thickness of the release layer is within the above range, the peel resistance of the release layer from the silicone pressure-sensitive adhesive can be reduced.

[0062] The laminate of the present invention is a laminate having a structure in which a pressure-sensitive adhesive layer (silicone pressure-sensitive adhesive layer) containing an organopolysiloxane is disposed opposite at least one release layer. "Opposite" means that the release layer and the pressure-sensitive adhesive layer are in direct contact. The structure of the laminate of the present invention is not particularly limited as long as it includes a structure in which the pressure-sensitive adhesive layer and the release layer are disposed opposite each other. Specific examples of laminates are described below.

[0063] The laminate of one embodiment of the present invention may be, for example, any of the following (a) to (d): (a) a laminate consisting of a first substrate / release layer / silicone pressure-sensitive adhesive layer / second substrate; (b) a laminate consisting of two or more consecutive structural units consisting of a substrate / release layer / silicone pressure-sensitive adhesive layer; (c) a laminate consisting of a first substrate / first release layer / silicone pressure-sensitive adhesive layer / second release layer / second substrate; (d) a laminate consisting of two or more consecutive structural units consisting of a substrate / first release layer / silicone pressure-sensitive adhesive layer / second release layer. In (b) and (d) above, either discontinuous or continuous substrates can be used as the substrate. Generally, when a discontinuous substrate is used, the laminate will be in the form of a sheet or film, and when a continuous substrate is used, the laminate will be in the form of a roll. The substrate material is not particularly limited, and any known material can be selected and used. Examples of suitable plastics include polyesters such as polyethylene terephthalate and polyethylene naphthalate; polyolefins such as polypropylene and polymethylpentene; polycarbonate; and polyvinyl acetate. The substrate may be a single layer, or may be a multilayer consisting of two or more layers of the same or different plastics. The thickness of the substrate is generally 10 to 300 μm, preferably 15 to 200 μm, and more preferably 20 to 125 μm.

[0064] The laminate of one embodiment of the present invention may be a sheet- or film-like laminate in which multiple sheet- or film-like members are stacked vertically, or may be a roll-like laminate wound around, for example, a cylindrical or tubular core.

[0065] Furthermore, in the laminate of one embodiment of the present invention, the silicone pressure-sensitive adhesive layer may be formed on the entire surface constituting the layer, or may be formed only on a part of the surface.The embodiment in which the silicone pressure-sensitive adhesive layer is formed only on a part of the surface is not particularly limited, and may be applied to form any shape, such as one or more dots, one or more straight lines, curves, or concentric circles.Similarly, the release layer may be formed on the entire surface constituting the release layer, or may be formed to match the shape of the silicone pressure-sensitive adhesive formed on the silicone pressure-sensitive adhesive layer.

[0066] The method for producing the laminate of the present invention is not particularly limited, and the laminate of one aspect of the present invention described above can be produced by a known method. For the method for producing the laminate, reference can be made to, for example, Patent Document 4 and the pamphlet of International Publication No. 2020 / 138413 referenced in Patent Document 4.

[0067] 3. Article As one aspect, the present invention provides an article including the laminate of one embodiment of the present invention (hereinafter also referred to as "article of the present invention"). The laminate is as described above in "2. Laminate". The article of one embodiment of the present invention may be in the form of a sheet, a roll, or a film.

[0068] The article according to one embodiment of the present invention is not particularly limited, and examples thereof include optical components such as liquid crystal panels, plasma displays, polarizing plates, and retardation plates; and electric / electronic components such as printed wiring boards, ICs, transistors, and capacitors.

[0069] The present invention will be further described below based on examples, but the present invention is not limited to the following examples.

[0070] Examples 1 to 13, Comparative Examples 1 to 5 The following components (A) to (F) were mixed uniformly to obtain curable organopolysiloxane compositions corresponding to Examples 1 to 13 and Comparative Examples 1 to 5. Each composition was then mixed with a toluene / heptane mixed solution (toluene:heptane=50:50) and diluted so that the total amount of components (A) to (D) was 5.3 mass% of the composition. A diluted solution of curable organopolysiloxane composition was then prepared by adding chloroplatinic acid / 1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex as component (G) in an amount such that the platinum metal content was 260 ppm relative to the total amount of components (A) to (D). Release sheets were then prepared from each composition using the methods described below for the peel resistance evaluation and residual adhesive strength tests described below. The contents (parts by mass) of components (A) to (C) are shown in Tables 1 to 3.

[0071] <Component (A)> Component (A1): A gum-like polydimethylsiloxane whose molecular chain terminals are capped with hydroxyl groups and whose side chains contain vinyl groups (plasticity at 25°C = 1.50, vinyl group content = 0.85% by mass). Component (A2): A gum-like polydimethylsiloxane whose molecular chain terminals are capped with trimethylsilyl groups and whose side chains contain hexenyl groups (plasticity at 25°C = 1.20, vinyl group content = 0.77% by mass). Component (A3): A gum-like polydimethylsiloxane whose molecular chain terminals are capped with trimethylsilyl groups and whose side chains contain hexenyl groups (plasticity at 25°C = 1.20, vinyl group content = 0.25% by mass).

[0072] <Component (B)> Component (B1): A gum-like organopolysiloxane whose molecular chain terminals are capped with hydroxyl groups and whose side chains contain no alkenyl groups (plasticity at 25°C = 1.60) Component (B2): A gum-like organopolysiloxane whose molecular chain terminals are capped with trimethylsilyl groups and whose side chains contain no alkenyl groups (plasticity at 25°C = 1.70) Component (B3): A liquid organopolysiloxane whose molecular chain terminals are capped with trimethylsilyl groups and whose side chains contain no alkenyl groups (viscosity at 25°C = 4,000,000 mPa·s) Component (B4): A liquid organopolysiloxane whose molecular chain terminals are capped with trimethylsilyl groups and whose side chains contain no alkenyl groups (viscosity at 25°C = 100,000 mPa·s) Component (B5): Gum-like organopolysiloxane having vinyl groups at the molecular chain terminals (plasticity at 25°C = 1.40; vinyl group content = 0.02% by mass)

[0073] <Component (C)> Component (C1): A liquid organopolysiloxane whose molecular chain terminals are capped with trimethylsilyl groups and whose side chains have phenyl groups (viscosity at 25°C = 50,000 mPa·s) Component (C2): A liquid organopolysiloxane whose molecular chain terminals are capped with hydroxyl groups and whose side chains have methyl groups (viscosity at 25°C = 14,000 mPa·s) Component (C3): A liquid organopolysiloxane whose molecular chain terminals are capped with trimethylsilyl groups and whose side chains have methyl groups (viscosity at 25°C = 5,000 mPa·s) Component (C4): A liquid organopolysiloxane whose molecular chain terminals are capped with trimethylsilyl groups and whose side chains have phenyl groups (viscosity at 25°C = 500 mPa·s)

[0074] <Component (D)> A mixture of the following components (D1) and (D2) in a mass ratio of 50:50 (amounts such that the SiH / Vi ratio in the composition is 1.3): Component (D1): methylhydrogenpolysiloxane capped at both molecular chain terminals with trimethylsilyl groups (viscosity at 25°C = 25 mPa·s) Component (D2): dimethylmethylhydrogenpolysiloxane capped at both molecular chain terminals with trimethylsilyl groups (viscosity at 25°C = 55 mPa·s)

[0075] <Component (E)> Toluene in an amount such that the total amount of components (A) to (C) is 30% by mass of the composition.

[0076] <Component (F)> 1.5 parts by mass of 3-methyl-1-butyn-3-ol per 100 parts by mass of component (A).

[0077] [Preparation of Release Sheets] The diluted solution of each prepared curable organopolysiloxane composition was applied to a release sheet in an amount of 0.50 g / m2 in terms of solid content excluding the solvent. ２ The composition was applied to the surface of a biaxially stretched polyester film (manufactured by Toray Industries, Inc., thickness 50 μm) using an OSP A-bar. After coating, the substrate coated with each composition was heat-treated for 60 seconds in a hot air circulating oven set at a temperature of 130°C, thereby forming a cured layer of organopolysiloxane on the surface of the polyester film substrate. The composition was then stored for 24 hours in a hot air circulating oven set at a temperature of 70°C to prepare a release sheet.

[0078] [Evaluation of Peel Resistance] A silicone pressure-sensitive adhesive tape MY2G (manufactured by Taiwan Symbio Co., Ltd.) was attached to the prepared release sheet by rolling a 2 kg roller back and forth twice. ２ The laminate sheet was produced by storing the laminate sheet in a hot air circulating oven set at 70°C for 24 hours under a pressure of 1000 gf / 25 mm. The resistance value (peel resistance) was then measured using a Tensilon tester when the tape was peeled from the laminate sheet at an angle of 180° and a speed of 0.3 m / min. The unit gf / 25 mm can be converted to N / 25 mm. The results are shown in Tables 1 to 3. Resistance values ​​exceeding 500 gf / 25 mm in the peel resistance evaluation were deemed to have failed at that point, and the residual adhesive strength evaluation described below was not carried out.

[0079] [Residual Adhesion Strength Evaluation] The tape after peeling in the peel resistance evaluation was reattached to a BA plate (SUS plate) by rolling a 2 kg roller back and forth twice, and then stored at room temperature for 1 hour or 24 hours. Thereafter, the resistance value (residual adhesive strength) was measured when the tape was peeled from this laminate sheet at an angle of 180 degrees and a speed of 0.3 m / min using a Tensilon tester. The results are shown in Tables 1 to 3. Tests that had a resistance value of 600 gf / 25 mm or more within 24 hours were judged to have passed.

[0080]

[0081] As shown in Tables 1 and 2, the release sheets made from the compositions of Examples 1 to 13 had low peel resistance and were releasable with low peel force. Furthermore, the release sheets made from the compositions of Examples 1 to 13 exhibited stable peel behavior. Furthermore, the release sheets made from the compositions of Examples 1 to 13 had good residual adhesive strength. While Examples 6 and 8 exhibited low residual adhesive strength after 1 hour, they exhibited good residual adhesive strength after 24 hours, demonstrating sufficient practicality. On the other hand, as shown in Table 3, the release sheet made from the composition of Comparative Example 1, which did not contain component (B), exhibited high peel resistance and was poor in practical use. Similarly, the release sheets made from the compositions of Comparative Example 2, which contained component (B4) with a viscosity of less than 500,000 mPa·s at 25°C, and Comparative Examples 3 and 4, which contained component (B5) having an alkenyl group in the molecule, also exhibited high peel resistance and were poor in practical use. Furthermore, the composition of Comparative Example 5, in which the content of component (B1) exceeded 80 parts by mass per 100 parts by mass of component (A), did not yield a good cured coating to begin with.

Claims

1. A laminate having a structure in which a pressure-sensitive adhesive layer containing an organopolysiloxane is disposed opposite at least one release layer, the release layer comprising: (A) 100 parts by mass of a linear organopolysiloxane having an alkenyl group and having 2 to 12 carbon atoms, the linear organopolysiloxane having a viscosity at 25°C of 1,000,000 mPa·s or more or having a plasticity at 25°C; (B) 5 to 80 parts by mass of a linear organopolysiloxane having no alkenyl group, the linear organopolysiloxane having a viscosity at 25°C of 500,000 mPa·s or more or having a plasticity at 25°C; (C) 0 to 20 parts by mass of a linear organopolysiloxane having no alkenyl group, the linear organopolysiloxane having a viscosity at 25°C of less than 500,000 mPa·s; A laminate comprising a cured product obtained by curing a curable organopolysiloxane composition comprising: (D) an organohydrogenpolysiloxane having two or more silicon-bonded hydrogen atoms (Si—H) in each molecule; and (E) a hydrosilylation reaction catalyst.

2. The laminate according to claim 1, wherein component (B) comprises a linear organopolysiloxane the molecular chain of which is terminally blocked with hydroxyl groups.

3. The laminate according to claim 1, wherein component (B) comprises a linear organopolysiloxane having both molecular chain terminals blocked with trialkylsilyl groups.

4. The laminate according to claim 1, wherein component (C) comprises a linear organopolysiloxane having both molecular chain terminals blocked with trialkylsilyl groups or hydroxyl groups.

5. The laminate according to claim 1, wherein component (C) comprises a linear organopolysiloxane having at least one group selected from the group consisting of an alkyl group having 1 to 12 carbon atoms and an aryl group on the side chain.

6. The laminate according to claim 1, wherein component (C) comprises a linear organopolysiloxane having at least one group selected from the group consisting of methyl groups and phenyl groups in its side chains.

7. The laminate according to claim 1, wherein component (D) contains an organohydrogenpolysiloxane having a viscosity of 1 to 1,000 mPa·s at 25° C. and both molecular chain terminals are blocked with trimethylsilyl groups.

8. The laminate according to claim 1, wherein the content of component (D) is an amount such that the molar ratio of silicon-bonded hydrogen atoms in component (D) to alkenyl groups in component (A) is 0.5 to 10.

0.

9. The laminate according to claim 1, wherein component (A) comprises a linear organopolysiloxane having alkenyl groups having 2 to 12 carbon atoms on the side chain, component (B) comprises a linear organopolysiloxane the molecular chain of which is terminally terminated with hydroxyl groups or terminally terminated with trimethylsilyl groups, and component (C) comprises a linear organopolysiloxane the molecular chain of which is terminally terminated with trimethylsilyl groups or hydroxyl groups.

10. The laminate of claim 1, which is free of fluorine-containing compounds.

11. The laminate according to claim 1, which is in the form of a sheet, roll or film.

12. An article comprising the laminate according to any one of claims 1 to 11.

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