TW202424112A - Curable organopolysiloxane composition and laminate - Google Patents

Abstract

The purpose of the present invention is to provide a curable organopolysiloxane composition which can form a cured coating film having stable release properties from an adhesive substance without impairing the adhesive properties of the adhesive substance. This composition contains: (A) a linear organopolysiloxane which has a viscosity at 25 DEG C of 20-1500 mPa.s and has a higher alkenyl group having 4-12 carbon atoms at a terminal and in a side chain of a molecular chain; (B) a linear organopolysiloxane which has a viscosity at 25 DEG C of 3000-50,000 mPa.s and has, in one molecule, at least two alkenyl groups having 2-12 carbon atoms only in side chains of a molecular chain, with the content of vinyl groups (CH2=CH-) in the alkenyl groups in component (B) being 0.1-0.3 mass%; (C) an organohydrogenpolysiloxane having at least two silicon atom-bonded hydrogen atoms per molecule; and (D) a hydrosilylation reaction catalyst.

Description

Curable organopolysiloxane composition and laminate

The present invention relates to a curable organopolysiloxane composition and a laminate made using the composition.

The curable organopolysiloxane composition can form a cured film with moderate peeling performance for adhesive substances, and is therefore used as a material for forming a peeling cured film. It is well known that the peeling resistance of the adhesive substance can be reduced by adding an organopolysiloxane that does not participate in the curing reaction to the composition. However, even such a composition is difficult to sufficiently reduce the peeling resistance, and instead has the problem of reducing the residual adhesion of the adhesive substance.

On the other hand, in recent years, there is a demand for solvent-free or low-solvent compositions. For example, Patent Document 1 proposes the following composition, which contains: a linear diorganopolysiloxane having a viscosity of 50 to 5,000 mPa·s at 25°C, with both ends of the molecular chain capped by trimethylsiloxy groups, and having at least two alkenyl groups with a carbon number of 4 or more on the side chain (the content of the alkenyl group in the siloxane is 0.2 to 10.0 mol% of all organic groups) and a viscosity of 50 to 5,000 mPa·s at 25°C. mPa·s, a mixture of a linear diorganopolysiloxane having at least two alkenyl groups in the molecule and end-capped with dimethylalkenylsiloxy groups at both ends of the molecular chain (in the siloxane, the alkenyl content is 0.2 to 10.0 mol% of all organic groups); an organohydropolysiloxane having a viscosity of 1 to 1,000 cSt at 25°C and having at least three silicon-atom-bonded hydrogen atoms in one molecule; and a platinum catalyst; in addition, patent document 2 proposes the following composition, which contains: a viscosity of 5 to 1,000 cSt at 25°C mPa·s, 99 to 90 parts by weight of a linear diorganopolysiloxane having a molecular chain end-capped by dimethylalkenylsiloxy groups and an alkenyl content of 0.2 to 10.0 mol% of all organic groups, and a viscosity of 1,000 to 10,000 mPa·s at 25°C, 1 to 10 parts by weight of a linear diorganopolysiloxane having a molecular chain end-capped by trimethylsiloxy groups and at least 2 alkenyl groups bonded to silicon atoms in the side chain and an alkenyl content of 0.05 to 0.5 mol% of all organic groups; an organohydropolysiloxane having a viscosity of 1 to 1,000 mPa·s at 25°C and at least 3 hydrogen atoms bonded to silicon atoms in one molecule; and a platinum catalyst.

However, when a peelable sheet having a peelable film made of such a composition is left at rest without a load or when it is subjected to a pressure treatment under a certain pressure, there is a problem that the peeling resistance of the adhesive substance changes. The peeling resistance of the adhesive substance increases due to the pressure treatment, resulting in heavy peeling, which limits its use.

In addition, there are attempts to reduce the peeling resistance of adhesive materials before and after the pressure treatment in order to suppress their re-peeling. However, there is a problem that the residual adhesion rate decreases after the adhesive material is peeled off. [Known technical literature] Patent literature

Patent document 1: Japanese Patent Publication No. 2000-160102 Patent document 2: Japanese Patent Publication No. 2002-201417

[The problem that the invention is trying to solve]

The purpose of the present invention is to provide a curable organopolysiloxane composition that can form a cured film with stable peeling performance and does not damage its adhesive performance for an adhesive substance. In addition, another purpose of the present invention is to provide a laminate having a cured film with stable peeling performance. [Technical means to solve the problem]

The curable organopolysiloxane composition of the present invention is characterized by comprising: (A) a linear organopolysiloxane having a viscosity of 20 to 1,500 mPa·s at 25°C and having a higher alkenyl group with a carbon number of 4 to 12 at the end and side chain of the molecular chain; (B) a linear organopolysiloxane having a viscosity of 3,000 to 50,000 mPa·s at 25°C and having at least 2 alkenyl groups with a carbon number of 2 to 12 only at the side chain of the molecular chain in one molecule, and the content of the vinyl group ( _CH2 =CH-) of the alkenyl group in component (B) is 0.1 to 0.3% by mass; (C) an organohydropolysiloxane having at least 2 silicon-atom-bonded hydrogen atoms in one molecule; and (D) A catalyst for hydrosilylation reaction with a catalytic amount; the mass ratio of the aforementioned component (A) to the aforementioned component (B) {component (A)/component (B)} is 90/10 to 75/25, and the ratio of the molar number of hydrogen atoms bonded to silicon atoms in the aforementioned component (C) to the total molar number of higher alkenyl groups in the aforementioned component (A) and alkenyl groups in the aforementioned component (B) is 0.5 to 5.0.

In the present composition, the higher alkenyl group in component (A) is preferably a hexenyl group, and the content of the vinyl group (CH ₂ =CH-) conversion of the hexenyl group in component (A) is 0.5 to 3.0 mass %.

In the present composition, it is preferred that both ends of the molecular chain of component (B) are capped with trialkylsilyl groups.

This composition is suitable for forming a peelable curing film.

The laminate of the present invention is characterized in that it has a cured material layer formed by curing the curable organopolysiloxane composition on at least one side of a sheet-like substrate.

In addition, the laminate of the present invention is characterized in that it has a peeling layer formed by curing the curable organic polysiloxane composition on at least one side of the sheet-like substrate, and an adhesive layer on the peeling layer. Effect of the invention

The curable organopolysiloxane composition of the present invention is characterized in that it can form a cured film with stable peeling performance and does not damage the adhesive performance of the adhesive material. In addition, the laminate of the present invention is characterized in that it has stable peeling performance.

＜Definition of Terms＞

The term "viscosity" used in this manual refers to the value at 25°C (unit: mPa·s or Pa·s) measured by a B-type rotational viscometer in accordance with JIS K 7117-1:1999 "Plastics - Liquid, emulsified or dispersed resins - Determination of apparent viscosity using a Brookfield rotational viscometer".

The term "molecular chain side chain" used in this specification refers to a bonding position other than the molecular chain terminal, and "having an alkenyl group on the molecular chain side chain" means that an alkenyl group is bonded to a silicon atom other than the molecular chain terminal of the linear organopolysiloxane.

The term "vinyl group (CH ₂ =CH-) conversion content" used in the present specification refers to the vinyl group content when the alkenyl group is converted to an equivalent mole of vinyl group.

First, the curable organopolysiloxane composition of the present invention is described in detail. [Component (A)]

Component (A) is a linear organic polysiloxane having a higher alkenyl group having 4 to 12 carbon atoms at the molecular chain terminal and side chain. Examples of the higher alkenyl group in component (A) include butenyl, pentenyl, hexenyl, heptenyl, and octenyl, preferably hexenyl. Examples of the group bonded to the silicon atom other than the higher alkenyl group in component (A) include alkyl groups having 1 to 12 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, and heptyl; aryl groups having 6 to 12 carbon atoms, such as phenyl, tolyl, and xylyl; aralkyl groups having 7 to 12 carbon atoms, such as benzyl and phenethyl; and fluoroalkyl groups having 3 to 12 carbon atoms, such as 3,3,3-trifluoropropyl, 4,4,4,3,3-pentafluorobutyl, 5,5,5,4,4,3,3-heptafluoropentyl, 6,6,6,5,5,4,4,3,3-nonafluorohexyl, and 7,7,7,6,6,5,5,4,4,3,3-undecafluoroheptyl. A methyl group is preferred. Furthermore, a small amount of hydroxyl groups and alkoxy groups having 1 to 3 carbon atoms such as methoxy and ethoxy groups may be bonded to the silicon atom in component (A) within the scope not impairing the purpose of the present invention.

The content of the higher alkenyl group of component (A) is not limited. When the higher alkenyl group is a hexenyl group, the content of the vinyl group (CH ₂ =CH-) of the aforementioned hexenyl group in component (A) is preferably in the range of 0.5 to 3.0 mass % or in the range of 0.5 to 2.0 mass %. The reason is that when the content of the hexenyl group of component (A) is above the lower limit of the above range, the composition is sufficiently cured, and the transfer of the silicone component of the obtained peelable cured film to the adhesive substance is suppressed, thereby suppressing the decrease in the residual adhesion rate of the adhesive substance. On the other hand, when the content of the hexenyl group of component (A) is below the upper limit of the above range, the obtained peelable cured film has a moderate light peel resistance.

The viscosity of component (A) at 25°C is in the range of 20 to 1,500 mPa·s, preferably in the range of 50 to 1,500 mPa·s, in the range of 50 to 1,000 mPa·s, or in the range of 100 to 500 mPa·s. The reason is that when the viscosity of component (A) is above the lower limit of the above range, the curability of the present composition can be improved, while on the other hand, when the viscosity of component (A) is below the upper limit of the above range, the peelable cured film obtained has relatively light peeling resistance and its change over time becomes small.

As such component (A), there can be cited dimethylsiloxane-methylhexenylsiloxane copolymers in which both ends of the molecular chain are capped with dimethylhexenylsiloxy groups, and methylhexenyl polysiloxane in which both ends of the molecular chain are capped with dimethylhexenylsiloxy groups. [Component (B)]

Component (B) is a linear organic polysiloxane having at least two alkenyl groups with carbon numbers of 2 to 12 only on the side chains of the molecular chain. Examples of the alkenyl group in component (B) include vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, and octenyl, preferably vinyl. Examples of the groups bonded to the silicon atom in component (B) other than the alkenyl group include alkyl groups with carbon numbers of 1 to 12, aryl groups with carbon numbers of 6 to 12, aralkyl groups with carbon numbers of 7 to 12, and fluoroalkyl groups with carbon numbers of 3 to 12 as exemplified in the aforementioned component (A), preferably methyl. In addition, component (B) has alkenyl groups only on the side chains of the molecular chain, and the groups at the ends of the molecular chain are not limited, and for example, trialkylsilyl groups are preferred. Examples of the trialkylsilyl group include trimethylsilyl and triethylsilyl. In addition, a small amount of hydroxyl groups and alkoxy groups having 1 to 3 carbon atoms such as methoxy and ethoxy groups may be bonded to the silicon atom in the component (B) within the scope not impairing the purpose of the present invention.

Regarding the content of the alkenyl group in component (B), the content of the vinyl group (CH ₂ =CH-) conversion of the alkenyl group is in the range of 0.1 to 0.3 mass %, preferably in the range of 0.1 to 0.25 mass % or in the range of 0.1 to 0.2 mass %. The reason is that when the content of the alkenyl group in component (B) is at least the lower limit of the above range, the composition is sufficiently cured, and the transfer of the silicone component of the obtained peelable cured film to the adhesive substance is suppressed, thereby suppressing the decrease in the residual adhesion rate of the adhesive substance. On the other hand, when the content of the alkenyl group in component (B) is at most the upper limit of the above range, the obtained peelable cured film has a moderate light peel resistance, and the change in peel resistance based on the presence or absence of pressure treatment becomes small.

The viscosity of component (B) at 25°C is in the range of 3,000 to 50,000 mPa·s, preferably in the range of 4,000 to 45,000 mPa·s. The reason is that when the viscosity of component (B) is above the lower limit of the above range, the curability of the present composition can be improved. On the other hand, when the viscosity of component (B) is below the upper limit of the above range, the obtained peelable cured film has a relatively light peel resistance, and the variation in peel resistance based on the presence or absence of pressurization treatment becomes smaller. In particular, when the viscosity of component (B) is low, its molecular weight becomes low, so even with the same alkenyl content, the number of alkenyl groups in one molecule becomes less. As a result, the reactivity of component (B) becomes low, so it is easy for the silicone component of the peelable cured film to transfer to the adhesive substance. In order to suppress this, a relatively high olefin content is preferred. On the other hand, when the viscosity is high, the molecular weight becomes higher, so even if the olefin content is the same, the number of olefins in one molecule increases. As a result, the reactivity of component (B) becomes higher, and the silicone component tends to remain inside the peelable cured film. In order to promote the localization of component (B) to the surface, it is effective to create a difference in relative reactivity with component (A), and in this regard, a relatively low olefin content is preferred.

Examples of such component (B) include dimethylsiloxane-methylvinylsiloxane copolymers having trimethylsiloxy groups capped at both ends of the molecular chain, methylvinylpolysiloxane having trimethylsiloxy groups capped at both ends of the molecular chain, and dimethylsiloxane-methylvinylsiloxane copolymers having dimethylhydroxysiloxy groups capped at both ends of the molecular chain.

In the present composition, the mass ratio of the above-mentioned component (A) to the above-mentioned component (B) {component (A)/component (B)} is in the range of 90/10 to 75/25, preferably in the range of 90/10 to 77/23. The reason is that when the mass ratio is above the lower limit of the above range, the curability of the present composition can be improved, especially the curability at a low temperature of about 100°C, and the strength of the obtained peelable cured film can be improved. On the other hand, when the mass ratio is below the upper limit of the above range, the obtained peelable cured film has a relatively light peeling resistance. In this composition, component (B) is formulated at a specific ratio relative to component (A), so that a relatively low peeling resistance can be formed, the change in peeling resistance based on the presence or absence of pressurization treatment is small, and the reduction in the residual adhesion rate of adhesive substances can be suppressed. [Component (C)]

Component (C) is an organic hydropolysiloxane having at least two hydrogen atoms bonded to silicon atoms in one molecule. As the groups bonded to silicon atoms other than hydrogen atoms in component (C), there can be exemplified the alkyl groups having 1 to 12 carbon atoms, the aryl groups having 6 to 12 carbon atoms, the aralkyl groups having 7 to 12 carbon atoms, and the fluoroalkyl groups having 3 to 12 carbon atoms listed in the aforementioned component (A), preferably the methyl group. Furthermore, a small amount of hydroxyl groups and alkoxy groups having 1 to 3 carbon atoms such as methoxy and ethoxy groups may be bonded to the silicon atoms in component (C) within the scope that does not impair the purpose of the present invention.

The viscosity of component (C) at 25°C is not limited, but is preferably in the range of 1 to 1,000 mPa·s or 5 to 500 mPa·s. The reason for this is that when the viscosity of component (C) is above the lower limit of the above range, the volatility of component (C) from the present composition is suppressed, and the composition is stable; on the other hand, when the viscosity of component (C) is below the upper limit of the above range, the curing property of the present composition is promoted.

The molecular structure of the component (C) is not limited, and examples thereof include a linear chain, a linear chain partially branched, a branched chain, a ring, or a resin. Examples of such component (C) include dimethylsiloxane-methylhydrosiloxane copolymers having both ends of the molecular chain blocked by trimethylsiloxy groups, dimethylsiloxane-methylhydrosiloxane copolymers having both ends of the molecular chain blocked by dimethylhydrosiloxy groups, dimethylpolysiloxane having both ends of the molecular chain blocked by dimethylhydrosiloxy groups, methylhydropolysiloxane having both ends of the molecular chain blocked by trimethylsiloxy groups, cyclomethylhydropolysiloxane, cyclomethylhydrosiloxane-dimethylsiloxane copolymers, copolymers containing siloxane units represented by the formula: H(CH ₃ ) ₂ SiO _1/2 and siloxane units represented by the formula: SiO _4/2 , and copolymers containing siloxane units represented by the formula: (CH ₃ ) ₃ SiO A copolymer of a siloxane unit represented by the formula: H(CH ₃ ) ₂ SiO _1/2 , a siloxane unit represented by the formula: H(CH 3 ) 2 SiO _1/2 , and a siloxane unit represented by the formula: SiO _4/2 .

In the present composition, the content of component (C) is an amount in the range of 0.5 to 5.0, preferably 0.5 to 3.0, or 1.0 to 3.0, of the molar number of hydrogen atoms bonded to silicon atoms in the present component relative to the total molar number of higher alkenyl groups in component (A) and alkenyl groups in component (B). The reason is that when the content of component (C) is above the lower limit of the above range, the curability of the present composition is improved, while on the other hand, when the content of component (C) is below the upper limit of the above range, the peeling cured film obtained is lightly peelable to adhesive substances. [Component (D)]

Component (D) is a catalyst for the hydrosilation reaction used to promote the curing reaction of the composition. Examples of component (D) include platinum-based catalysts, palladium-based catalysts, and rhodium-based catalysts, and platinum-based catalysts are preferred. The platinum catalyst is a catalyst containing platinum metal, and specifically, chloroplatinic acid, alcohol-modified chloroplatinic acid, olefin complex of chloroplatinic acid, complex of chloroplatinic acid and ketone, complex of chloroplatinic acid and vinyl siloxane, platinum tetrachloride, platinum powder, solid platinum supported on a carrier of alumina or silica, platinum black, olefin complex of platinum, alkenyl siloxane complex of platinum, carbonyl complex of platinum, and thermoplastic organic resin powders such as methyl methacrylate resin, polycarbonate resin, polystyrene resin, silicone resin, etc. containing the platinum catalysts can be cited. Particularly preferred are platinum siloxane complexes such as a complex of chloroplatinic acid and divinyltetramethyldisiloxane, a complex of chloroplatinic acid and tetramethyltetravinylcyclotetrasiloxane, a platinum divinyltetramethyldisiloxane complex, and a platinum tetramethyltetravinylcyclotetrasiloxane complex.

The content of component (D) is the amount of a catalyst that promotes the hydrosilylation reaction of the present composition. Specifically, the amount of the catalyst metal in the present composition is in the range of 1 to 1,000 ppm, or in the range of 5 to 500 ppm, in terms of mass unit, relative to the total amount of components (A) to (C). The reason for this is that if the content of component (D) is above the lower limit of the above range, the curing of the present composition is promoted, while on the other hand, if the content of component (D) is below the upper limit of the above range, the obtained peelable cured film is less likely to be colored.

In order to adjust the curing speed, the composition may contain (E) a silanization reaction inhibitor. Examples of such component (E) include alkynols such as 2-methyl-3-butyn-2-ol, 3,5-dimethyl-1-hexyn-3-ol, 3-methyl-1-pentyn-3-ol, 2-phenyl-3-butyn-2-ol, 1-ethynyl-1-cyclohexanol, 2-ethynyl isopropanol, and 2-ethynylbutane-2-ol; trimethyl (3,5-dimethyl-1-hexyn-3 Silylated acetylenic alcohols such as [(1,1-dimethyl-2-propynyl)oxy]trimethylsilane, [(1,1-dimethyl-2-propynyl)oxy]trimethylsilane, [(1,1-dimethyl-2-propynyl)oxy]trimethylsilane] ... -1-yne, 3-methyl-3-hexene-1-yne, 1-ethynylcyclohexene, 3-ethyl-3-butene-1-yne, and 3-phenyl-3-butene-1-yne and other enyne compounds; diallyl maleate, dimethyl maleate, diethyl fumarate, diallyl fumarate, bis-2-methoxy-1-methylethyl maleate, monooctyl maleate, monoisooctyl maleate, Unsaturated carboxylic acid esters such as monoallyl maleate, monomethyl maleate, monoethyl fumarate, monoallyl fumarate, and 2-methoxy-1-methylethyl maleate; alkenyl siloxanes such as 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane and 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane; and benzotriazole.

In the present composition, the content of component (E) is not limited, but is preferably 0.001 parts by mass or more, 0.01 parts by mass or more, or 0.1 parts by mass or more, and on the other hand, is 5 parts by mass or less, or 3 parts by mass or less, relative to 100 parts by mass of the total of component (A) and component (B).

The composition can be used substantially without a solvent, or can be used after being diluted with a known organic solvent. Examples of the organic solvent include aromatic hydrocarbon solvents such as toluene and xylene; aliphatic hydrocarbon solvents such as hexane, octane, and isoparaffin; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ester solvents such as ethyl acetate and isobutyl acetate; ether solvents such as diisopropyl ether and 1,4-dioxane; cyclic polysiloxanes with a polymerization degree of 3 to 6 such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and decamethylcyclopentasiloxane; and halogenated hydrocarbons such as trichloroethylene, perchloroethylene, trifluorotoluene, 1,3-bis(trifluoromethyl)benzene, and methylpentafluorobenzene. Especially when applying a thin layer on a thin sheet substrate such as polyolefin with low heat resistance, ether solvents are preferred in terms of curability and swelling properties.

The composition may also contain the following as optional components: a thickener composed of an alkoxysilane compound such as 3-glycidyloxypropyltrimethoxysilane and 3-methacryloyloxypropyltrimethoxysilane; an antioxidant such as phenols, quinones, amines, phosphorus, phosphites, sulfurs, and thioethers; a light stabilizer such as triazoles and benzophenones; a flame retardant such as phosphates, halogens, phosphorus, and antimony; one or more antistatic agents composed of cationic surfactants, anionic surfactants, and nonionic surfactants; and well-known additives such as heat-resistant agents, dyes, and pigments.

In addition, in terms of the excellent physical properties and peeling properties of the obtained cured film, the composition can be cured by energy rays (also called chemical action rays), such as ultraviolet rays or electron beams, especially ultraviolet irradiation. At this time, curing using ultraviolet rays includes curing using only ultraviolet rays, or curing using ultraviolet rays and heat. In order to give the composition good ultraviolet curing properties, it can further contain (F) a photopolymerization initiator. Component (F) is a component that gives ultraviolet curing properties to the composition, and has the following advantages: by combining the thermal curing of the addition reaction with the ultraviolet curing, the heat damage caused to the plastic film substrate with low heat resistance can be reduced, and the adhesion of the cured product obtained by curing the composition to the plastic film can be improved. Furthermore, it has the following advantages: it can prevent the silicone component from migrating from the surface of the cured film obtained by curing the composition to the thin sheet, causing the thin sheet to be contaminated by the silicone component (this is called the transferability of silicone), and further reduce the transferability of silicone.

The component (F) can be appropriately selected from compounds known as compounds that generate free radicals by ultraviolet irradiation, such as organic peroxides, carbonyl compounds, organic sulfur compounds and azo compounds. Specifically, acetophenone, propiophenone, benzophenone, xanthol, fluorene, benzaldehyde, anthraquinone, triphenylamine, 4-methylacetophenone, 3-pentylacetophenone, 4-methoxyacetophenone, 3-bromoacetophenone, Acetophenone, 4-allylacetophenone, p-diethylbenzene, 3-methoxybenzophenone, 4-methylbenzophenone, 4-chlorobenzophenone, 4,4-dimethoxybenzophenone, 4-chloro-4-benzylbenzophenone, 3-chlorobenzophenone, 3,9-dichlorobenzophenone, 3-chloro-8-nonylbenzophenone, benzoin, benzoin methyl ether, benzoin butyl ether, bis(4-dimethylaminophenyl)ketone, benzyl methoxy ketal, 2-chloro-9-oxysulfuron , diethylacetophenone, 2-methyl[4-(methylthio)phenyl]2- The component (F) may be 1-propanol, 2,2-dimethoxy-2-phenylacetophenone, diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, or a mixture of two or more thereof, and diethoxyacetophenone and 1-hydroxycyclohexyl phenyl ketone are particularly preferred.

The content of component (F) is not limited, but is preferably in the range of 0.01 to 10 parts by mass or 0.01 to 2.5 parts by mass relative to 100 parts by mass of component (A). If the content of component (F) is within the above range, the peelable cured film obtained by curing the composition can improve the silicone transfer property and improve the physical properties such as mechanical strength. [Preparation method of the composition]

The composition can be produced by uniformly mixing the above-mentioned components (A) to (D), and further component (E) and any other arbitrary components. The order of adding the components is not particularly limited. When the components are not used immediately after mixing, it is preferred to mix components (A), (B) and (C), store them separately from component (D), and mix the two before use. In addition, in the composition containing components (A) to (D) and (E), by adjusting the content of component (E), a composition that does not crosslink at room temperature but crosslinks and solidifies when heated can be produced.

By uniformly coating the composition on a thin sheet substrate and heating it under conditions sufficient to cause component (A) and component (C) to undergo a silane hydrolysis reaction and crosslink, a thin sheet substrate having a cured layer on the surface of the thin sheet substrate having smoothness, transparency, and excellent adhesion to the thin sheet substrate can be produced. In addition, the cured layer formed by curing the composition has the following advantages: excellent softness and air permeability, and rarely involves bubbles when adhered to a non-planar object. Therefore, it is extremely suitable for use in optical displays, protective films on glass surfaces, etc., which require both the peeling properties of the cured layer and the adhesion properties of the cured layer to the object to be protected.

The laminate of the present invention is described in detail below.

The laminate is characterized in that at least one surface of a sheet-like substrate has a cured material layer formed by curing the composition.

In the present laminate, the sheet-like substrate is not limited, for example, polyesters such as polyethylene terephthalate and polyethylene naphthalate; polyolefins such as polypropylene and polymethylpentene; polycarbonate; polyimide; and plastics such as polyvinyl acetate; and Japanese paper, paperboard, corrugated paperboard, glass paper, clay-coated paper, polyolefin laminated paper, polyethylene laminated paper, synthetic paper, and other papers; natural fiber cloth, synthetic fiber cloth, artificial leather cloth, and other cloths; and glass wool and metal foil. The film may be a single layer, or may be composed of two or more layers of the same or different plastics. As the substrate, a plastic film is preferred, especially a polyester film, and a polyethylene terephthalate film is further preferred, and a biaxially oriented polyethylene terephthalate film is particularly preferred. Polyethylene terephthalate film is not prone to generate dust during processing and use. Therefore, it is possible to effectively prevent dust from causing poor coating of adhesive substances on the peeling sheet. In addition, by performing an antistatic treatment on the polyethylene terephthalate film and using it as a substrate, problems such as poor coating of adhesive substances can be effectively prevented.

The thickness of the sheet-like substrate is not particularly limited, but is generally 10 to 300 µm, preferably 15 to 200 µm, and particularly preferably 20 to 125 µm.

Furthermore, in order to improve the adhesion between the thin sheet substrate and the cured layer, a support film that has been treated with a primer, a corona treatment, an etching treatment, or a plasma treatment may be used. In addition, examples of primer compositions that may be used include: a condensation-type silicone primer composition containing a polydiorganosiloxane having a terminal SiOH group, a polysiloxane having a SiH group, and/or a polysiloxane having an alkoxy group, and a condensation reaction catalyst; and an addition-type silicone primer composition containing a polydiorganopolysiloxane having an alkenyl group such as a vinyl group, a polysiloxane having a SiH group, and an addition reaction catalyst.

The surface of the sheet-like substrate opposite to the cured layer may also be subjected to surface treatment, such as anti-scratch, anti-fouling, anti-fingerprint, anti-glare, anti-reflection, anti-static and the like. The above surface treatment may be applied to the sheet-like substrate after the composition is applied, or the composition may be applied after the surface treatment is applied in advance. For example, the anti-scratch treatment (hard coating treatment) may be performed using hard coating agents such as acrylates, silicones, cyclohexane, inorganics, and organic-inorganic hybrids. For example, the anti-fouling treatment may be performed using anti-fouling agents such as fluorine, silicones, ceramics, and photocatalysts. Examples of anti-reflection treatment include wet treatment by coating fluorine-based, silicone-based, and other anti-reflection agents, and dry treatment by evaporation or sputtering. Examples of anti-static treatment include treatment using surfactant-based, silicone-based, organic boron-based, conductive polymer-based, metal oxide-based, and evaporated metal-based anti-static agents.

The temperature for curing the composition on a flaky substrate is generally suitable to be 50 to 200°C. If the flaky substrate has good heat resistance, it may be above 200°C. The heating method is not particularly limited, and examples include heating in a hot air circulation oven, heating through a long heating furnace, and heat radiation from an infrared lamp or a halogen lamp. Moreover, curing may also be performed by heating and ultraviolet irradiation. If component (D) is a platinum vinyl siloxane complex catalyst, even if its formulation amount is 1 to 5,000 ppm in terms of platinum metal relative to the total amount of the composition, a cured layer with excellent smoothness, transparency, and adhesion to a flaky substrate can be easily obtained at 100 to 150°C in a short time of 1 to 40 seconds.

On the other hand, for a flaky substrate such as polyolefin having low heat resistance, the composition is applied to the flaky substrate such as polyolefin and then heated at a low temperature of preferably 50°C to 100°C, more preferably 50°C to 80°C. In this case, the curing time is 30 seconds to several minutes (e.g., 1 to 10 minutes) to achieve stable curing.

There are no particular limitations on the method of applying the composition to the surface of the sheet-like substrate, and dipping, spraying, gravure printing, offset printing, gravure offset printing, roll coating using an offset transfer roll, reverse roll coating, air knife coating, curtain coating using a curtain flow coating, comma blade coating, Meyer bar coating, and other well-known methods for forming a cured layer can be used. The thickness of the release cured film on the substrate is not limited, but is preferably in the range of 0.01 to 3 µm or in the range of 0.03 to 2 µm. The reason for this is that if the thickness of the peelable cured film is at least the lower limit of the above range, the adhesive substance can be easily peeled off, while on the other hand, if it is below the upper limit of the above range, the occurrence of blocking can be suppressed when the obtained peelable sheet is rolled into a roll.

This composition is used to form a cured layer with excellent surface smoothness and release properties to adhesive substances. It can be used particularly as a releasable cured film forming agent for engineering paper, asphalt packaging paper, and various plastic films.

In addition, the present laminate is characterized in that a peeling layer formed by curing the present composition is provided on at least one side of a sheet-like substrate, and an adhesive layer is provided on the peeling layer.

In particular, the peeling layer formed by curing the composition has excellent peeling properties for other adhesive layers, and can therefore be used as a release layer for laminates including an adhesive layer, such as construction paper, adhesive material packaging paper, adhesive tape, and adhesive labels. Specifically, by using the composition, the following laminate can be obtained: a sheet-like substrate having a cured layer (release layer or peeling layer) formed by heat-curing the composition on at least one side of the sheet-like substrate, and an adhesive sheet having an adhesive layer (or adhesive layer) on at least one side of the sheet-like substrate, and the adhesive layer is bonded in such a way that the adhesive layer contacts the cured layer.

The adhesive material used in the laminate is various adhesives, various adhesives, etc., and examples thereof include acrylic adhesives, rubber adhesives, silicone adhesives; acrylic adhesives, synthetic rubber adhesives, silicone adhesives, epoxy adhesives, and polyurethane adhesives. In addition, examples thereof include asphalt, rice cakes and other adhesive foods, pastes, and bird glue.

On the other hand, the cured layer composed of the composition can be used as an adhesive layer with the same excellent peeling property as when the composition is applied thinly, especially by applying the composition thickly, and is extremely useful in terms of being used as an adhesive layer such as a protective sheet and a re-peelable adhesive sheet. The adhesive layer has the following advantages: after being pasted on an object, the adhesive force is stably maintained for a long time, and the pasting position does not shift or peel off, and the re-peeling property is excellent after long-term pasting. In addition, it has the following advantages: it is easy to re-paste, and the cured layer is not easily deformed, whitened, and the paste residue is not likely to occur when the protective sheet is used for a long time.

The protective sheet or removable adhesive sheet having a cured layer composed of the present composition is used for attaching to the surface of metal plates, painted metal plates, aluminum window frames, resin plates, decorative steel plates, vinyl chloride laminated steel plates, glass plates and other components for protection during transportation, processing or aging. In addition, it can be preferably used as a protective sheet used in the manufacturing process of various liquid crystal display panels (also called screens or displays), the distribution process of polarizing plates, the manufacturing process and distribution process of resin components for various machines such as automobiles, and food packaging.

Similarly, the protective sheet having an adhesive layer composed of the cured layer of the composition is easy to re-stick, and is therefore suitable for the following various display protective sheets. The protective sheet of the present invention can be used for the purpose of preventing scratches, dirt, fingerprint adhesion, static electricity, reflection, and peeping on the surface of the display in various situations during the manufacture, distribution, and use of the display.

Specifically, the laminate as the surface protection sheet can be obtained by using the present composition in the form of a laminate having a sheet-like substrate provided with a cured layer (peel-off layer and adhesive layer) formed by heat-curing the present composition on at least one side of the sheet-like substrate, and a peel-off sheet provided with a peel-off layer on at least one side of the sheet-like substrate and pasted in such a manner that the peel-off layer contacts the cured layer. Example

The curable organopolysiloxane composition and the laminate of the present invention are described in more detail by way of examples. However, the present invention is not limited to the examples. In addition, the viscosity in the examples is the value at 25°C measured by a DV1 type rotational viscometer manufactured by Brookfield Company in accordance with JIS K 7117-1:1999 "Plastics - Liquid, emulsified or dispersed resins - Determination of apparent viscosity using a Brookfield rotational viscometer".

The preparation and evaluation of the peeling sheet are carried out as follows. ＜Preparation method of peeling sheet＞

Using a printing suitability tester [Ming Seisakusho Co., Ltd.; RI-2], a curable organopolysiloxane composition was applied to the surface of the substrate in a silicone conversion of 0.6 g/ ^m2 . After application, it was heated in a hot air circulation oven at 120°C for 30 seconds to produce a release sheet having a release cured film on the surface of the substrate. <Aging of release sheet (pressurization treatment)>

A portion of the peeling sheets made by the above method were placed at 23°C and 65% RH without load to produce "untreated peeling sheets". The other peeling sheets were treated at 20 g/ ^cm2 pressure for 20 hours at 23°C and 65% RH to produce "pressure-treated peeling sheets". <Peeling resistance of adhesive substances>

Use an applicator to evenly apply an acrylic adhesive [manufactured by Toyo INK Co., Ltd., trade name Oribain BPS5127] to the surface of the release cured film in a wet form to a thickness of 70 µm, and dry at 70°C for 2 minutes. Then, after bonding double-sided coated paper (manufactured by Kobayashi Create Co., Ltd.) to it, a load of 20 g/ ^cm2 is applied, and it is placed at 25°C and 60% humidity for 1 day. Then, using a tensile tester, the peeling force when the bonded paper is stretched in a 180° direction at a speed of 0.3 m/min is measured. In addition, the peeling force is required to be less than 150 mN/50 mm in both the untreated release sheet and the pressure-treated release sheet. ＜Repeating ionization rate＞

The re-peeling ionization rate is calculated by measuring the peeling resistance of the peeling sheet after the above-mentioned aging and the untreated peeling sheet under pressure, and using the following formula. Re-peeling ionization rate = (peeling resistance of the peeling sheet after the pressure treatment / peeling resistance of the untreated peeling sheet) In addition, the re-peeling ionization rate is required to be 1.10 or less. ＜Residual adhesion rate＞

Adhesive tape No. 31B manufactured by Nitto Denko Corporation was pasted on the peeling sheet, a load of 20 g/cm ² was applied, and the sheet was placed at a temperature of 70°C for 20 hours. Then, the adhesive tape was torn off, and the torn adhesive tape was pasted on a stainless steel plate, a load of 20 g/cm ² was applied, and the sheet was placed in air at a temperature of 25°C and a humidity of 60% for 30 minutes. Then, the adhesive tape was stretched at an angle of 180 degrees and a peeling speed of 0.3 m/min using a tensile tester [tensile force universal tester manufactured by A&D Co., Ltd.], and the force required for peeling (gf1) was measured. In addition, as a blank test, the above-mentioned tape was attached to a Teflon (registered trademark) sheet in the same manner as above, and the force (gf2) required to peel off the adhesive tape was measured according to the above operation. The residual adhesion rate (%) was calculated based on these values according to the following formula. Residual adhesion rate (%) = (gf1/gf2) × 100 In addition, the residual adhesion rate is required to be 90% or more. <Examples 1 to 6, Comparative Examples 1 to 19>

The following components were uniformly mixed in a manner to form the composition shown in Tables 1 to 4 to prepare a curable organopolysiloxane composition. In addition, in the table, the content of component (D) is relative to the total amount of components (A) to (C), and the platinum in component (D) is an amount of 100 ppm in mass units. In addition, "component (A)/component (B)" in the table represents the ratio of the content of component (A)/the content of component (B), and "SiH/ _CH2 =CH" represents the ratio of the molar number of hydrogen atoms bonded to silicon atoms in component (C) relative to the total molar number of alkenyl groups in components (A) and (B). The properties of the peeling sheet prepared using the curable organopolysiloxane composition prepared in the above manner were measured, and the results are shown in Tables 1 to 4.

As component (A), the following components were used. (a-1): Dimethylsiloxane-methylhexenylsiloxane copolymer (hexenyl vinyl equivalent content = 1.15 mass %) with a viscosity of 200 mPa·s and a molecular chain end-capped with dimethylhexenylsiloxy groups at both ends

In addition, for the comparison of component (A), the following components were used. (a-2): Dimethylsiloxane-methylhexenylsiloxane copolymer with a viscosity of 200 mPa·s and a molecular chain end-capped with dimethylvinylsiloxy groups (vinyl content of vinyl and hexenyl groups = 1.10 mass%) (a-3): Dimethylsiloxane-methylvinylsiloxane copolymer with a viscosity of 350 mPa·s and a molecular chain end-capped with dimethylvinylsiloxane groups (vinyl content = 0.94 mass%) (a-4): Dimethylsiloxane-methylhexenylsiloxane copolymer with a viscosity of 350 mPa·s and a molecular chain end-capped with trimethylsiloxy groups (vinyl content of hexenyl groups = 1.25 mass%)

As component (B), the following components are used. (b-1): Dimethylsiloxane-methylvinylsiloxane copolymer with trimethylsiloxy groups at both ends of the molecular chain having a viscosity of 5,000 mPa·s (vinyl content = 0.15 mass%) (b-2): Dimethylsiloxane-methylvinylsiloxane copolymer with trimethylsiloxy groups at both ends of the molecular chain having a viscosity of 40,000 mPa·s (vinyl content = 0.15 mass%)

In addition, for the comparison of component (B), the following components were used. (b-3): dimethylsiloxane-methylvinylsiloxane copolymer with a molecular chain end-capped by trimethylsiloxy groups at both ends (vinyl content = 0.5 mass %) with a viscosity of 35,000 mPa·s (b-4): dimethylsiloxane-methylvinylsiloxane copolymer with a molecular chain end-capped by trimethylsiloxy groups at both ends (vinyl content = 0.31 mass %) with a viscosity of 8,000 mPa·s (b-5): dimethylpolysiloxane with a molecular chain end-capped by trimethylsiloxy groups at both ends (b-6): dimethylpolysiloxane with a molecular chain end-capped by trimethylsiloxy groups at both ends (b-7): viscosity of 10,000 mPa·s, dimethyl polysiloxane with trimethylsiloxy end-capping at both ends of the molecular chain (b-8): dimethyl polysiloxane with dimethylhydroxysiloxy end-capping at both ends of the molecular chain (b-9): dimethyl polysiloxane with dimethylhydroxysiloxy end-capping at both ends of the molecular chain (b-10): dimethyl polysiloxane with dimethylhydroxysiloxy end-capping at both ends of the molecular chain (b-11): dimethyl polysiloxane with dimethylvinylsiloxy end-capping at both ends of the molecular chain (b-12): viscosity 10,000 mPa·s mPa·s, dimethyl polysiloxane with dimethyl vinyl end-capped at both ends of the molecular chain (vinyl content = 0.13 mass%)

As component (C), the following components are used. (c-1): Methyl hydropolysiloxane with a molecular chain end-capped by trimethylsiloxy groups at both ends with a viscosity of 20 mPa·s (content of hydrogen atoms bonded to silicon atoms = 1.58 mass %)

As component (D), the following components are used. (d-1): 1,3-divinyltetramethyldisiloxane solution of platinum-1,3-divinyltetramethyldisiloxane complex (platinum content = 6,500 ppm)

As the component (E), the following components were used. (e-1): 1-ethynylcyclohexane-1-ol

[Table 1] Implementation Example 1 2 3 4 5 6 (Parts by weight) Composition of curable organopolysiloxane composition (A) (a-1) 87.03 87.03 82.19 77.36 82.19 77.36 (a-2) 0 0 0 0 0 0 (a-3) 0 0 0 0 0 0 (a-4) 0 0 0 0 0 0 (B) (b-1) 10.00 0 15.00 20.00 0 0 (b-2) 0 10.00 0 0 15.00 20.00 (b-3) 0 0 0 0 0 0 (b-4) 0 0 0 0 0 0 (b-5) 0 0 0 0 0 0 (b-6) 0 0 0 0 0 0 (b-7) 0 0 0 0 0 0 (b-8) 0 0 0 0 0 0 (b-9) 0 0 0 0 0 0 (b-10) 0 0 0 0 0 0 (b-11) 0 0 0 0 0 0 (b-12) 0 0 0 0 0 0 (C) (c-1) 2.70 2.70 2.55 2.40 2.55 2.40 (D) (d-1) 1.50 1.50 1.50 1.50 1.50 1.50 (E) (e-1) 0.27 0.27 0.26 0.24 0.26 0.24 Ingredient (A) / Ingredient (B) 90/10 90/10 85/15 80/20 85/15 80/20 SiH/CH _２ =CH 1.1 1.1 1.1 1.1 1.1 1.1 Peeling resistance (mN/50 mm) Unprocessed 130 130 140 130 145 135 Pressure treatment 140 135 150 140 150 145 Restripping rate 1.08 1.04 1.07 1.08 1.03 1.07 Residual adhesion rate (%) 95.5 96.4 91.8 90.0 92.7 92.7

[Table 2] Comparison Example 1 2 3 4 5 6 7 (Parts by weight) Composition of curable organopolysiloxane composition (A) (a-1) 87.03 87.03 87.03 87.03 87.03 87.03 87.03 (a-2) 0 0 0 0 0 0 0 (a-3) 0 0 0 0 0 0 0 (a-4) 0 0 0 0 0 0 0 (B) (b-1) 0 0 0 0 0 0 0 (b-2) 0 0 0 0 0 0 0 (b-3) 10.00 0 0 0 0 0 0 (b-4) 0 10.00 0 0 0 0 0 (b-5) 0 0 10.00 0 0 0 0 (b-6) 0 0 0 10.00 0 0 0 (b-7) 0 0 0 0 10.00 0 0 (b-8) 0 0 0 0 0 10.00 0 (b-9) 0 0 0 0 0 0 10.00 (b-10) 0 0 0 0 0 0 0 (b-11) 0 0 0 0 0 0 0 (b-12) 0 0 0 0 0 0 0 (C) (c-1) 2.70 2.70 2.70 2.70 2.70 2.70 2.70 (D) (d-1) 1.50 1.50 1.50 1.50 1.50 1.50 1.50 (E) (e-1) 0.27 0.27 0.27 0.27 0.27 0.27 0.27 Ingredient (A) / Ingredient (B) 90/10 90/10 90/10 90/10 90/10 90/10 90/10 SiH/CH _２ =CH 1.1 1.1 1.1 1.1 1.1 1.1 1.1 Peeling resistance (mN/50 mm) Unprocessed 145 145 160 140 140 150 150 Pressure treatment 160 155 185 175 165 175 180 Restripping rate 1.10 1.07 1.16 1.25 1.18 1.17 1.20 Residual adhesion rate (%) 97.3 98.2 83.6 80.0 76.4 71.8 72.7

[table 3] Comparison Example 8 9 10 11 12 13 (Parts by weight) Composition of curable organopolysiloxane composition (A) (a-1) 87.03 87.03 87.03 0 0 0 (a-2) 0 0 0 87.03 0 0 (a-3) 0 0 0 0 87.03 0 (a-4) 0 0 0 0 0 87.03 (B) (b-1) 0 0 0 10.00 10.00 10.00 (b-2) 0 0 0 0 0 0 (b-3) 0 0 0 0 0 0 (b-4) 0 0 0 0 0 0 (b-5) 0 0 0 0 0 0 (b-6) 0 0 0 0 0 0 (b-7) 0 0 0 0 0 0 (b-8) 0 0 0 0 0 0 (b-9) 0 0 0 0 0 0 (b-10) 10.00 0 0 0 0 0 (b-11) 0 10.00 0 0 0 0 (b-12) 0 0 10.00 0 0 0 (C) (c-1) 2.70 2.70 2.70 2.70 2.70 2.70 (D) (d-1) 1.50 1.50 1.50 1.50 1.50 1.50 (E) (e-1) 0.27 0.27 0.27 0.27 0.27 0.27 Ingredient (A) / Ingredient (B) 90/10 90/10 90/10 90/10 90/10 90/10 SiH/CH _２ =CH 1.1 1.1 1.1 1.2 1.4 1.1 Peeling resistance (mN/50 mm) Unprocessed 150 180 180 140 160 115 Pressure treatment 180 190 190 155 200 130 Restripping rate 1.20 1.06 1.06 1.11 1.25 1.13 Residual adhesion rate (%) 69.1 97.9 97.8 95.9 95.3 82.0

[Table 4] Comparison Example 14 15 16 17 18 19 (Parts by weight) Composition of curable organopolysiloxane composition (A) (a-1) 90.37 71.03 66.19 90.37 71.03 66.19 (a-2) 0 0 0 0 0 0 (a-3) 0 0 0 0 0 0 (a-4) 0 0 0 0 0 0 (B) (b-1) 5.00 25.00 30.00 0 0 0 (b-2) 0 0 0 5.00 25.00 30.00 (b-3) 0 0 0 0 0 0 (b-4) 0 0 0 0 0 0 (b-5) 0 0 0 0 0 0 (b-6) 0 0 0 0 0 0 (b-7) 0 0 0 0 0 0 (b-8) 0 0 0 0 0 0 (b-9) 0 0 0 0 0 0 (b-10) 0 0 0 0 0 0 (b-11) 0 0 0 0 0 0 (b-12) 0 0 0 0 0 0 (C) (c-1) 2.85 2.25 2.10 2.85 2.25 2.10 (D) (d-1) 1.50 1.50 1.50 1.50 1.50 1.50 (E) (e-1) 0.29 0.23 0.21 0.29 0.23 0.21 Ingredient (A) / Ingredient (B) 95/5 74/26 69/31 95/5 74/26 69/31 SiH/CH _２ =CH 1.2 1.1 1.1 1.2 1.1 1.1 Peeling resistance (mN/50 mm) Unprocessed 155 125 110 155 120 120 Pressure treatment 160 135 115 170 120 125 Restripping rate 1.03 1.08 1.05 1.10 1.00 1.04 Residual adhesion rate (%) 99.1 83.6 80.0 98.2 87.3 80.0

From the results in Tables 1 to 4, it can be seen that when a dimethylsiloxane-methylvinylsiloxane copolymer having a vinyl content exceeding 0.3% by mass and having both ends of the molecular chain capped by trimethylsiloxy groups is used as component (B) (Comparative Examples 1 and 2), the peeling resistance after the pressure treatment becomes larger, that is, heavy peeling occurs. In addition, it can be seen that even when a dimethylsiloxane-methylvinylsiloxane copolymer having a vinyl content of less than 0.3% by mass and having both ends of the molecular chain capped by trimethylsiloxy groups is used as component (B), if the ratio of component (A)/component (B) is outside the range of 90/10 to 75/25, sufficient light peeling is difficult (Comparative Examples 14 and 17), and the residual adhesion rate is significantly reduced (Comparative Examples 15, 16, 18, and 19). In addition, it can be seen that when dimethylpolysiloxane with trimethylsilyl groups capped at both ends of the molecular chain is used as component (B) (Comparative Examples 3 to 5) and dimethylpolysiloxane with dimethylsilanol groups capped at both ends of the molecular chain is used as component (B) (Comparative Examples 6 to 8), the tendency of heavy stripping is large and the residual adhesion rate is significantly reduced. Furthermore, when a dimethylsiloxane-methylvinylsiloxane copolymer with a vinyl content of 0.3 mass % or less and dimethylvinyl groups capped at both ends of the molecular chain is used as component (B) (Comparative Examples 9 and 10), although the heavy stripping rate and residual adhesion rate are good, the stripping resistance becomes large. Furthermore, it can be seen that when a dimethylsiloxane-methylhexenylsiloxane copolymer having a hexenyl group only in the side chain of the molecular chain is used as component (A) (Comparative Example 13), the tendency of re-exfoliation is large and the residual adhesion rate is also low.

In contrast, it can be seen that in the present invention (Examples 1 to 6), the peeling resistance is small, the re-peeling rate is low when the cured peeling sheet is subjected to overpressure treatment, and the residual adhesion rate will not be reduced. [Industrial Applicability]

The curable organopolysiloxane composition of the present invention can form a cured film with stable peeling performance and without damaging the adhesive performance of adhesive substances, and is therefore suitable as a composition for forming a peelable cured film. That is, even when a release sheet obtained by coating the present composition on a sheet-like substrate such as polyethylene laminated paper and curing the resulting sheet is laminated and pressurized, the release layer composed of the present composition has little difference from the release layer not subjected to the pressurization treatment, has stable release performance, and can suppress the decrease in the adhesion of the adhesive substance, thereby providing a laminated body having a release layer and an adhesive layer using the above-mentioned composition, like a release adhesive tape/sheet.

without

without

Claims (9)

A curable organopolysiloxane composition comprising: (A) a linear organopolysiloxane having a viscosity of 20 to 1,500 mPa·s at 25°C and having a higher alkenyl group with a carbon number of 4 to 12 at the end and side chain of the molecular chain; (B) a linear organopolysiloxane having a viscosity of 3,000 to 50,000 mPa·s at 25°C and having at least 2 alkenyl groups with a carbon number of 2 to 12 only at the side chain of the molecular chain in one molecule, and wherein the content of the vinyl group ( _CH2 =CH-) of the alkenyl group in component (B) is 0.1 to 0.3% by mass; (C) an organohydropolysiloxane having at least 2 silicon-atom-bonded hydrogen atoms in one molecule; and (D) A catalyst for hydrosilylation reaction with a catalytic amount; the mass ratio of the aforementioned component (A) to the aforementioned component (B) {component (A)/component (B)} is 90/10 to 75/25, and the ratio of the molar number of hydrogen atoms bonded to silicon atoms in the aforementioned component (C) to the total molar number of higher alkenyl groups in the aforementioned component (A) and alkenyl groups in the aforementioned component (B) is 0.5 to 5.0. The curable organopolysiloxane composition of claim 1, wherein the higher alkenyl group in component (A) is a hexenyl group, and the content of the vinyl group (CH ₂ =CH-) converted in the hexenyl group in component (A) is 0.5 to 3.0 mass %. The curable organopolysiloxane composition of claim 1 or 2, wherein both ends of the molecular chain of component (B) are capped with trialkylsiloxy groups. The curable organopolysiloxane composition of claim 1 or 2 is used to form a releasable cured film. The curable organopolysiloxane composition of claim 3 is used to form a releasable cured film. A laminate having a cured layer formed by curing the curable organopolysiloxane composition of claim 1 or 2 on at least one side of a sheet-like substrate. A laminate having a cured material layer formed by curing the curable organopolysiloxane composition of claim 3 on at least one surface of a sheet-like substrate. A laminate having a peeling layer formed by curing the curable organopolysiloxane composition of claim 1 or 2 on at least one side of a sheet-like substrate, and an adhesive layer on the peeling layer. A laminate having a peeling layer formed by curing the curable organopolysiloxane composition as claimed in claim 3 on at least one side of a sheet-like substrate, and an adhesive layer on the peeling layer.