Curable silicone composition, release coating agent for silicone pressure sensitive adhesive, release film, and laminate comprising said composition

Abstract

[Problem] To provide a curable silicone composition for a release agent that can form a release film in which, even when the film is thin, the release force is small from a silicone adhesive, particularly from a silicone adhesive having a low storage modulus at a low temperature. Further, to provide: a release film that has a low release force and that has superior smoothness of an adhesive layer surface after release; a laminate; and a method for producing said laminate. [Solution] A curable silicone composition comprising: (A) a mixture of two or more types of fluoroalkyl group-containing organopolysiloxanes which are not compatible with each other, which each include a fluoroalkyl group and an alkenyl group, and in which the contained amounts of fluoroalkyl groups are different from each other; (B) an organohydrogen polysiloxane; (C) an organopolysiloxane that has a fluorine atom-containing organic group and that does not include a hydrosilylation reaction-causing group; (D) a catalyst for hydrosilylation reaction; and (E) an organic solvent. A use of a release film or the like provided with a cured product of said curable silicone composition.

Description

[Technical Field]

[0001] The present invention relates to a curable silicone composition, a release coating comprising the composition, in particular a release coating for silicone pressure-sensitive adhesives (pressure-sensitive adhesives) that have a low storage modulus at low temperatures, a release film using the release coating, in particular a release film for silicone pressure-sensitive adhesives, and a laminate comprising the release film, in particular a laminate comprising a release film and a silicone pressure-sensitive adhesive. [Background technology]

[0002] Silicone pressure-sensitive adhesives (pressure-sensitive adhesives) have excellent heat resistance, cold resistance, weather resistance, chemical resistance, and electrical insulation properties, and have therefore been widely used as adhesives for industrial protective tapes, masking tapes, and various medical functional tapes. In recent years, they have also been used in so-called assembly applications, such as bonding optical components for liquid crystal displays (display devices, functional films, lenses, etc.). Because silicone pressure-sensitive adhesives adhere strongly to surfaces coated with silicone rubber or silicone-based materials, they cannot be used with conventional silicone release agents used for acrylic or organic rubber-based pressure-sensitive adhesives. Therefore, various curable silicone release agent compositions have been proposed for forming release films that can easily release silicone pressure-sensitive adhesives. These compositions are coated on flexible substrates such as plastic films as release coating agents to form release films, which are then laminated with silicone pressure-sensitive adhesives to form sheet- or roll-shaped tapes, etc.

[0003] For example, Patent Document 1 proposes a curable coating composition as a release agent for silicone pressure-sensitive adhesives, which comprises an organopolysiloxane having at least 300 silicon atoms and containing 0.5 to 2 mol % of vinyl group-containing siloxane units and 30 mol % of fluoroalkyl group-containing siloxane units, an organohydrogenpolysiloxane having an average of at least two silicon-bonded hydrogen atoms per molecule and compatible with the organopolysiloxane, a hydrosilylation reaction catalyst, and a hydrosilylation reaction inhibitor.

[0004] Furthermore, Patent Document 2 proposes a release agent composition for silicone pressure-sensitive adhesives that contains two types of fluoroalkyl-modified polydimethylsiloxanes with different amounts of alkenyl groups for the purpose of achieving light release, and a release sheet formed by applying this to a substrate.

[0005] Furthermore, Patent Document 3 proposes a release agent composition for silicone pressure-sensitive adhesives, which is composed of an organopolysiloxane having an alkenyl-containing organic group and a fluoroalkyl group, an organohydrogenpolysiloxane having at least three silicon-bonded hydrogen atoms in one molecule, a hydrosilylation reaction catalyst, an organic solvent, and an organopolysiloxane having an alkenyl group but no fluoroalkyl group, for the purpose of adjusting the release force, and a release film formed by applying the composition to a plastic film.

[0006] Patent Document 4 proposes an organosiloxane release control agent that has a fluorine atom-containing organic group and does not contain a hydrosilylation reactive group, a release agent composition containing the same, and a release sheet that includes a cured layer made of the cured product of the same.

[0007] Patent Document 5 proposes a curable silicone composition comprising a combination of two or more organopolysiloxanes having a fluoroalkyl group and at least two alkenyl groups in the molecule, which, when mixed without a solvent, are stirred at 25°C, left to stand for 24 hours, and then visually observed to be completely incompatible or completely incompatible; a release sheet comprising a release layer made of a cured product obtained by curing the composition; and a laminate comprising a structural unit in which a silicone pressure-sensitive adhesive layer is laminated on a release layer.

[0008] However, these documents do not describe or suggest anything about combining a specific release control agent with a specific curable silicone composition, and in particular, they do not describe or suggest anything about the significantly more significant effects that would be achieved in technical terms with silicone pressure-sensitive adhesives that have a low storage modulus at low temperatures, or about the industrial significance of such combinations. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 2-245031 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-60554 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-182391 [Patent Document 4] Special publication WO2016-006252 [Patent Document 5] Special publication WO2020-138413 Summary of the Invention [Problem to be solved by the invention]

[0010] The inventors have discovered a new technical problem. Specifically, when a release film is peeled off from a release laminate containing a silicone pressure-sensitive adhesive (also known as a "pressure-sensitive adhesive," hereinafter), a lower and more stable peel force is required to improve the efficiency of the peeling process and to prevent the surface of the silicone pressure-sensitive adhesive from becoming rough after peeling. However, in recent years, there has been an increasing demand for silicone-based optically clear pressure-sensitive adhesives (OCAs) for bonding and constructing display devices such as flexible displays and touch panels. For these applications, a pressure-sensitive adhesive layer with sufficient viscoelasticity and a low storage modulus is required, particularly at low temperatures (such as -20°C).

[0011]

[0005] However, when a conventionally known composition is used as a release coating to form a release film and further a laminate, the peel force between the release layer and a silicone pressure-sensitive adhesive layer having a low storage modulus at the low temperatures described above cannot be sufficiently reduced, and even if peeling occurs, problems such as roughness or wrinkles may occur on the surface of the silicone pressure-sensitive adhesive after peeling of the release film, which may impair transparency and visibility and have adverse effects on yield and performance. If a release agent layer that can be peeled while maintaining a sufficiently small peel force and a good, smooth adhesive surface could be realized for a silicone pressure-sensitive adhesive with these new properties, silicone pressure-sensitive adhesives with excellent low-temperature properties could be more effectively utilized industrially.

[0012]

[0006] Specifically, the object of the present invention is to provide a release film that can be peeled off with a low peel force from a silicone pressure-sensitive adhesive adhered to the release layer, even if the release layer is thin, particularly from a silicone pressure-sensitive adhesive having a low storage modulus at low temperatures, and that has a stable release force for silicone pressure-sensitive adhesives, a release agent for such a release film, a curable silicone composition that can be used as a release agent, and a laminate comprising a substrate, a silicone pressure-sensitive adhesive layer, and a release agent layer. Release films generally have a release layer formed by coating a release agent on a flexible substrate such as a plastic film. [Means for solving the problem]

[0013] The present inventors discovered that the above-mentioned problems could be solved by a hydrosilylation-curable silicone composition that uses a combination of (A) two or more organopolysiloxanes having a fluoroalkyl group and at least two alkenyl groups in the molecule, which, when mixed without a solvent, are found to be completely incompatible or completely immiscible when visually observed after stirring at 25°C and standing for 24 hours, and (C) an organopolysiloxane that has a fluorine atom-containing organic group and no hydrosilylation-reactive group, and completed the present invention.

[0014] That is, the curable silicone composition of the present invention is characterized by being hydrosilylation-curable and using a mixture of organopolysiloxanes having specific fluorine-containing organic groups and alkenyl groups as the main agent, with the further addition of an organopolysiloxane having a fluorine-containing organic group that does not contribute to the hydrosilylation reaction.Furthermore, the present invention is characterized by a release coating agent, a release film, and a laminate that utilize a release layer obtained by curing the curable silicone composition as a release layer for silicone pressure-sensitive adhesives, particularly silicone pressure-sensitive adhesives with a low storage modulus at low temperatures.

[0015] Specifically, the curable silicone composition of the present invention comprises: (A) a mixture of two or more types of fluoroalkyl group-containing organopolysiloxanes each having a fluoroalkyl group and at least two alkenyl groups in one molecule, with the fluoroalkyl group contents being different from one another, wherein the two or more types of fluoroalkyl group-containing organopolysiloxanes are not completely miscible at 25°C when mixed without a solvent; (B) an organohydrogenpolysiloxane having at least three silicon-bonded hydrogen atoms in each molecule; (C) an organopolysiloxane having a fluorine atom-containing organic group and not containing a hydrosilylation reactive group; (D) a catalyst for a hydrosilylation reaction, and (E) Organic solvent It includes:

[0016] Furthermore, the above-mentioned problems can be solved by a release coating agent, a release film, and a laminate that utilize a release layer obtained by curing the curable silicone composition as a release layer for a silicone pressure-sensitive adhesive having a storage modulus of 5 MPa or less at -20°C. [Effects of the Invention]

[0017] By using the curable silicone composition of the present invention as a release coating agent, it is possible to form a release film that can peel a silicone pressure-sensitive adhesive adhered to the release layer, particularly a silicone pressure-sensitive adhesive with a low storage modulus at low temperatures, from the release layer with a low peel force, even if the release layer is thin. Furthermore, the release film and laminate of the present invention can stably peel a silicone pressure-sensitive adhesive arranged on the release layer (including both a pressure-sensitive adhesive formed by a curing reaction on the release layer and a release layer attached to an already formed pressure-sensitive adhesive) from the release layer with a low peel force, and can maintain a uniform adhesive surface with little roughness or wrinkles after peeling, making them suitable for use as components for display devices and electronic materials that require a uniform adhesive surface.

[0018] In particular, by utilizing a release layer obtained by curing the curable silicone composition of the present invention, it is possible to provide release films and release laminates that exhibit low release force and good release properties for silicone pressure-sensitive adhesives, particularly sheet-type / film-type pressure-sensitive adhesives, that have a storage modulus of 5 MPa or less at -20°C, which have been difficult to handle and produce release laminates from using conventional release agents.This makes it possible to expand the range of industrial uses of silicone pressure-sensitive adhesives that have good viscoelasticity at low temperatures. DETAILED DESCRIPTION OF THE INVENTION

[0019] First, the curable silicone composition of the present invention will be described in detail.

[0020] [Curable Silicone Composition] The curable silicone composition of the present invention comprises: (A) a mixture of two or more types of fluoroalkyl group-containing organopolysiloxanes each having a fluoroalkyl group and at least two alkenyl groups in one molecule, with the fluoroalkyl group contents being different from one another, wherein the two or more types of fluoroalkyl group-containing organopolysiloxanes are not completely miscible at 25°C when mixed without a solvent; (B) an organohydrogenpolysiloxane having at least three silicon-bonded hydrogen atoms in each molecule; (C) an organopolysiloxane having a fluorine atom-containing organic group and not containing a hydrosilylation reactive group; (D) a catalyst for a hydrosilylation reaction, and (E) Organic solvent and optionally (F) a hydrosilylation reaction inhibitor and other optional components. These essential components and other components will be described below.

[0021] [Component (A)] Component (A) is a mixture of two or more fluoroalkyl-containing organopolysiloxanes, each containing a fluoroalkyl group and at least two alkenyl groups per molecule, with the fluoroalkyl group contents differing from one another. Furthermore, the two or more fluoroalkyl-containing organopolysiloxanes must be a combination that is not completely miscible at 25°C when mixed without a solvent. "Not completely miscible at 25°C when mixed without a solvent" means that when a mixture of two or more fluoroalkyl-containing organopolysiloxanes is placed in a transparent glass vial with a lid and thoroughly stirred at 25°C, and then visually observed immediately and 24 hours later, the mixture becomes cloudy or separates into two phases, and does not remain a homogeneous, clear liquid. In addition, when the fluoroalkyl group-containing organopolysiloxane is in a state other than a liquid such as a gum or paste at 25°C, this refers to the state where the mixture is heated to a temperature at which it becomes liquid, thoroughly stirred, and then cooled to 25°C, and when visually observed immediately after and 24 hours later, the mixture is cloudy or separated into two phases, and does not exhibit a homogeneous, transparent liquid state. Mixtures using these components in combination achieve a release force for silicone pressure-sensitive adhesives that is lower than the arithmetic mean estimated from the results when each component is used alone, and when used in combination with component (C) described below, the release force between a silicone pressure-sensitive adhesive layer with a low storage modulus at low temperatures and a release layer can be sufficiently reduced, and the silicone pressure-sensitive adhesive surface can be maintained with little roughness or wrinkles after peeling.

[0022] Specifically, component (A) has the following average composition formula (I): (R 1 3SiO 1 / 2 ) a (R 1 2SiO 2 / 2 ) b (R 1 SiO 3 / 2 ) c (SiO 4 / 2 ) d (I) (In the formula, R 1are the same or different and independently represent an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or a fluoroalkyl group having 1 to 12 carbon atoms, and at least two R 1 is the alkenyl group, and at least one R 1 is a fluoroalkyl group having 1 to 12 carbon atoms, a is a positive number, b is a positive number, c is 0 or a positive number, and d is 0 or a positive number. Preferably, the organopolysiloxane is represented by the following formula: In addition, in formula (I), R 1 may contain a small amount of hydroxyl groups or alkoxy groups as long as the object of the present invention is not impaired.

[0023] In formula (I), R 1 The alkyl group having 1 to 12 carbon atoms that can be represented by is preferably a methyl group.

[0024] In formula (I), R 1 The alkenyl groups having 2 to 12 carbon atoms that can be represented by are preferably independently a vinyl group or a hexenyl group, and a vinyl group is particularly preferred. 1 is an alkenyl group, and the content of the alkenyl group, calculated as a vinyl group, is not particularly limited as long as it can be used to form a curable composition, but is preferably 2.0 mass% or less, more preferably 1.0 mass% or less, and even more preferably 0.5 mass% or less. This is because if the alkenyl group content is higher than necessary, when the curable silicone composition of the present invention is used as a release coating agent to form a release layer for a silicone pressure-sensitive adhesive, the peel strength of the release layer from the silicone pressure-sensitive adhesive layer may increase. Note that the content of alkenyl groups, calculated as a vinyl group, means the content calculated by replacing alkenyl groups other than vinyl groups with the mass of an equimolar amount of vinyl groups.

[0025] In formula (I), R 1 Examples of the aryl group having 6 to 12 carbon atoms that can be represented include a phenyl group, a tolyl group, and a xylyl group, with a phenyl group being preferred.

[0026] In formula (I), R 1 Examples of the aralkyl group having 7 to 12 carbon atoms that can be represented include a benzyl group and a phenylethyl group.

[0027] In formula (I), R 1 Examples of the fluoroalkyl group having 1 to 12 carbon atoms that can be represented include a 3,3,3-trifluoropropyl group, a 3,3,4,4,4-pentafluorobutyl group, a 3,3,4,4,5,5,5-heptafluoropentyl group, a 3,3,4,4,5,5,6,6,6-nonafluorohexyl group, a 3,3,4,4,5,5,6,6,7,7,7-undecafluoroheptyl group, a 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl group, and a 3,3,4,4,5,5,6,6,7,7,8,8,9,9,9-pentadecafluorononyl group, with a 3,3,4,4,5,5,6,6,6-nonafluorohexyl group being preferred.

[0028] With respect to a to d in formula (I) above, a is an integer of 2 or greater, preferably 2 to 6, b is an integer of 1 or greater, preferably 1 to 5,000, and more preferably 30 to 4,000, c is 0 or a positive number, and d is 0 or a positive number. With regard to component (A), if the degree of siloxane polymerization is below the lower limit of the above range, it may be difficult to form a release layer when the curable silicone composition obtained using this component is used as a release coating agent. If the degree of siloxane polymerization exceeds the upper limit of the above range, the coatability (particularly thin film coatability) of the resulting curable silicone composition may be reduced.

[0029] The two or more fluoroalkyl group-containing organopolysiloxanes that make up component (A) are preferably a mixture of two or more organopolysiloxanes each represented by the above formula (I), and it is particularly preferred that component (A) is a mixture of the following components (A1) and (A2):

[0030] (A1) one or more linear or branched organopolysiloxanes containing fluoroalkyl group-containing organodisiloxane units and having a fluorine atom content of 40% by mass or more, preferably 41% by mass or more, and more preferably 42% by mass or more; and (A2) One or more linear or branched organopolysiloxanes containing fluoroalkyl group-containing organodisiloxane units and having a fluorine atom content of less than 40% by mass, preferably 39% by mass or less, and more preferably 38% by mass or less.

[0031] That is, the component (A1) is a compound represented by "R 1 2SiO 2 / 2 Two R units expressed as 1 at least one of the above, preferably one of the above, is a fluoroalkyl group having 1 to 12 carbon atoms, particularly preferably a 3,3,4,4,5,5,6,6,6-nonafluorohexyl group, and the proportion of the mass of fluorine atoms to the mass of the entire compound represented by formula (I) is 40 mass% or more, preferably 41 mass% or more, and further preferably 42 mass% or more.

[0032] In addition, the component (A2) is a compound represented by the formula (I) above, which is represented by "R 1 2SiO 2 / 2 Two R units expressed as 1 and wherein at least one, preferably one, of the above is a fluoroalkyl group having 1 to 12 carbon atoms, particularly preferably a 3,3,4,4,5,5,6,6,6-nonafluorohexyl group, and the proportion of the mass of fluorine atoms to the mass of the entire compound represented by formula (I) is less than 40 mass%, preferably 39 mass% or less, and more preferably 38 mass% or less.

[0033] Therefore, the fluorine atom contents of components (A1) and (A2) are different. The difference between the fluorine atom contents of components (A1) and (A2) is preferably greater than 3% by mass, and more preferably 4% by mass or greater. This is because when the difference in fluorine atom content between components (A1) and (A2) is within the above range, the two components tend to become incompatible.

[0034] In one embodiment of the present invention, it is preferred that, while the above-mentioned conditions for the fluorine atom content of components (A1) and (A2) are satisfied, component (A1) is one or more linear or branched organopolysiloxanes containing fluoroalkyl group-containing organodisiloxane units, where the fluoroalkyl groups are 3,3,4,4,5,5,6,6,6-nonafluorohexyl groups, and said units account for 39 mol% or more of all organosiloxane units, and component (A2) is one or more linear or branched organopolysiloxanes containing fluoroalkyl group-containing organodisiloxane units, where the fluoroalkyl groups are 3,3,4,4,5,5,6,6,6-nonafluorohexyl groups, and said units account for 36 mol% or less of all organosiloxane units.

[0035] Specific examples of components (A1) and (A2) include, but are not limited to, the fluoroalkyl group-containing organopolysiloxanes shown below: In the following formula, Me, Vi, Hex, Fa1, Fa2, and Fa3 represent a methyl group, a vinyl group, an n-hexenyl group, a 3,3,4,4,5,5,6,6,6-nonafluorohexyl group, a 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl group, and a 3,3,3-trifluoropropyl group, respectively. Average formula: (Me2ViSiO 1 / 2 )2(Me2SiO 2 / 2 ) 750 (Me(Fa1)SiO 2 / 2 ) 750 (MeViSiO 2 / 2 ) 20 An organopolysiloxane represented by the formula: Average formula: (MeSiO 1 / 2 )2(Me2SiO 2 / 2 ) 450 (Me(Fa1)SiO 2 / 2 ) 350 (MeViSiO 2 / 2 ) 10 An organopolysiloxane represented by the formula: Average formula: (Me2(Fa1)SiO 1 / 2 )2(Me2SiO 2 / 2 ) 450 (Me(Fa1)SiO 2 / 2 ) 350 (MeViSiO 2 / 2 ) 10 An organopolysiloxane represented by the formula: Average formula: (Me2HexSiO 1 / 2 )2(Me2SiO 2 / 2 ) 1000 (Me(Fa1)SiO 2 / 2 ) 1000 (MeHexSiO 2 / 2 ) 20 An organopolysiloxane represented by the formula: Average formula: (Me2ViSiO 1 / 2 )4(Me2SiO 2 / 2 ) 500 (Me(Fa1)SiO 2 / 2 ) 500 (SiO 4 / 2 )1 An organopolysiloxane represented by the formula: Average formula: (Me2ViSiO 1 / 2 )2(Me2SiO 2 / 2 ) 500 (Me(Fa)SiO 2 / 2 ) 500 MeViSiO 2 / 2 ) 10 An organopolysiloxane represented by the formula: Average formula: (Me2ViSiO 1 / 2 )2(Me2SiO 2 / 2 ) 1470 (Me(Fa1)SiO 2 / 2 ) 1100 (MeViSiO 2 / 2 )8 An organopolysiloxane represented by the formula: Average formula: (Me2ViSiO 1 / 2 )2(Me2SiO 2 / 2 ) 1280 (Me(Fa1)SiO 2 / 2 ) 1270 (MeViSiO 2 / 2 )7 An organopolysiloxane represented by the formula: Average formula: (Me2ViSiO 1 / 2 )2(Me2SiO 2 / 2 ) 900 (Me(Fa1)SiO 2 / 2 ) 450 (MeViSiO 2 / 2 ) 10 An organopolysiloxane represented by the formula: Average formula: (Me2ViSiO 1 / 2 )2(Me2SiO 2 / 2 ) 1100 (Me(Fa1)SiO 2 / 2 ) 400 (MeViSiO 2 / 2 )7 An organopolysiloxane represented by the formula: Average formula: (Me2ViSiO 1 / 2 )2(Me2SiO 2 / 2 ) 1100 (Me(Fa1)SiO 2 / 2 ) 400 (Me(Fa)SiO 2 / 2 ) 100 (MeViSiO 2 / 2 ) 10 Organopolysiloxane represented by the formula:

[0036] In the curable silicone composition of the present invention, the mass ratio of component (A1) to component (A2) contained in the composition is preferably 1 / 99 to 99 / 1 ((A1) / (A2)), more preferably 10 / 90 to 90 / 10, even more preferably 20 / 80 to 80 / 20, and most preferably 30 / 70 to 70 / 30. When components (A1) and (A2) are used in combination, a release force for a silicone pressure-sensitive adhesive that is lower than the release force estimated by arithmetic mean based on the results when component (A1) or component (A2) is used alone instead of component (A1).

[0037] [(B) Component] Component (B) is an organopolysiloxane having at least three silicon-bonded hydrogen atoms (Si-H) per molecule, and undergoes a hydrosilylation addition reaction with component (A) to cure the composition of the present invention. In particular, component (B) may contain a certain amount of a fluorine-containing organic group selected from a fluoroalkyl group having 1 to 12 carbon atoms and a fluoro(poly)ether-containing organic group, and this is preferred from the viewpoint of the technical effects of the present invention.

[0038] Examples of groups other than hydrogen atoms bonded to silicon atoms in component (B) include alkyl groups having 1 to 12 carbon atoms, aryl groups having 6 to 12 carbon atoms, aralkyl groups having 7 to 12 carbon atoms, fluoroalkyl groups having 1 to 12 carbon atoms, and fluoro(poly)ether-containing organic groups having 2 to 100 carbon atoms. Furthermore, small amounts of hydroxyl groups or alkoxy groups may be bonded to silicon atoms in component (B) as long as the object of the present invention is not impaired.

[0039] The molecular structure of component (B) is not limited, and examples include linear, branched, partially branched linear, resinous, and cyclic structures, with linear or partially branched linear structures being preferred.

[0040] Such component (B) is preferably a compound represented by the following average composition formula (II): (R 2 3SiO 1 / 2 ) aa (R 2 2SiO 2 / 2 )ab (R 2 SiO 3 / 2 ) ac (SiO 4 / 2 ) ad (II) Examples of organopolysiloxanes include those represented by the following formula:

[0041] In formula (II), R 2 are the same or different and independently represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, a fluoroalkyl group having 1 to 12 carbon atoms, or a fluoro(poly)ether-containing organic group, with the proviso that R 2 At least three of the groups are hydrogen atoms. Furthermore, aa is a positive number, ab is a positive number, ac is 0 or a positive number, and ad is 0 or a positive number. However, when aa is 2, the total of aa to ad is preferably within the range of 5 to 200, with the lower limit being 10 or 15, and the upper limit being 150, 120, 100, 80, 70, 60, 50, or 40. This is because, when aa is 2, if the total of aa to ad is equal to or greater than the lower limit of the above range, crosslinking of the composition proceeds sufficiently, whereas if it is equal to or less than the upper limit of the above range, handling and workability of the composition are good.

[0042] R 2 Examples of the alkyl group having 1 to 12 carbon atoms that can be represented include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, and a dodecyl group, and a methyl group is preferred.

[0043] Also, R 2 Examples of the aryl group having 6 to 12 carbon atoms that can be represented include a phenyl group, a tolyl group, and a xylyl group, with a phenyl group being preferred.

[0044] Also, R 2 Examples of the aralkyl group having 7 to 12 carbon atoms that can be represented include a benzyl group and a phenylethyl group.

[0045] Furthermore, R 2 Examples of the fluoroalkyl group having 1 to 12 carbon atoms that can be represented by the formula (I) include a 3,3,3-trifluoropropyl group, a 3,3,4,4,4-pentafluorobutyl group, a 3,3,4,4,5,5,5-heptafluoropentyl group, a 3,3,4,4,5,5,6,6,6-nonafluorohexyl group, a 3,3,4,4,5,5,6,6,7,7,7-undecafluoroheptyl group, a 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl group, and a 3,3,4,4,5,5,6,6, An example is a 7,7,8,8,9,9,9-pentadecafluorononyl group, and a group selected from a 3,3,4,4,5,5,5-heptafluoropentyl group, a 3,3,4,4,5,5,6,6,6-nonafluorohexyl group, a 3,3,4,4,5,5,6,6,7,7,7-undecafluoroheptyl group, and a 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl group is preferred, with a 3,3,4,4,5,5,6,6,6-nonafluorohexyl group being particularly preferred.

[0046] Also, R 2 The fluoro(poly)ether-containing organic group that can be represented by R 1 The fluoro(poly)ether-containing organic groups exemplified in are preferably used.

[0047] The component (B) of the present invention may have a group selected from a fluoroalkyl group and a fluoro(poly)ether-containing organic group, but it does not have to have one. Even if an organohydrogenpolysiloxane having a fluorine atom-containing group is not used as the component (B), by combining it with the above-mentioned component (A), when the composition of the present invention is used as a coating agent and cured, a release layer with excellent releasability, particularly excellent releasability for silicone pressure-sensitive adhesives, can be obtained. However, from the viewpoint of the technical effect of the present invention, it is particularly preferable that the component (B) has a certain amount of these fluorine atom-containing groups. As the component (B), an organohydrogenpolysiloxane represented by the above average composition formula (II), R 2However, organopolyhydrogensiloxanes containing a combination of hydrogen atoms, alkyl groups (especially methyl groups), and fluoroalkyl groups and / or fluoro(poly)ether-containing organic groups are particularly preferred.

[0048] When component (B) of the present invention has a group selected from the group consisting of a fluoroalkyl group and a fluoro(poly)ether-containing organic group, the content of fluorine atoms derived from the fluoroalkyl group and / or the fluoro(poly)ether-containing organic group in the molecule is not particularly limited, but is preferably at least 20 mass%, at least 25 mass%, at least 30 mass%, or at least 35 mass%. The upper limit of the fluorine atom content in component (B) is preferably at most 60 mass%, or at most 50 mass%.

[0049] Specific examples of component (B) include, but are not limited to, the organopolysiloxanes shown below. In the following formula, Me, F2a, and F1b represent a methyl group, a 3,3,4,4,5,5,6,6,6-nonafluorohexyl group, and a group represented by the following formula: F[CF(CF3)CF2O]2CF(CF3)CH2O-(CH2)3- represents a group represented by the formula: Average formula: (MeSiO 1 / 2 )2(Me(F2aSiO 2 / 2 ) 12 (MeHSiO 2 / 2 ) 27 An organopolysiloxane represented by the formula: Average formula: (MeSiO 1 / 2 )2(Me2SiO 2 / 2 ) 55 (Me(FbSiO 2 / 2 ) 25 (MeHSiO 2 / 2 ) 25 An organopolysiloxane represented by the formula: Average formula: (MeSiO 1 / 2 )2(MeHSiO 2 / 2) 50 An organopolysiloxane represented by the formula: Average formula: (MeSiO 1 / 2 )2(Me2SiO 2 / 2 ) 30 (MeHSiO 2 / 2 ) 30 An organopolysiloxane represented by the formula: Average formula: (MeHSiO 1 / 2 )2(Me2SiO 2 / 2 ) 30 (MeHSiO 2 / 2 ) 30 Organopolysiloxane represented by the formula: One or a combination of two or more selected from these can be used as component (B).

[0050] The content of component (B) in the curable silicone composition of the present invention is an amount such that the molar ratio of silicon-bonded hydrogen atoms to alkenyl groups in component (A) is within the range of 0.1 to 20 (silicon-bonded hydrogen atoms / alkenyl groups), and is preferably within any combination of upper and lower limits such that the lower limit is 0.5, 0.8, or 1, and the upper limit is 18, 17, 16, 15, 14, 13, or 12. This is because when the content of component (B) is at or above the lower limit of this range, crosslinking of the curable silicone composition proceeds sufficiently, while when the content is below the upper limit of this range, the properties of the resulting release coating can be stabilized.

[0051] [(C) component] Component (C) is an organopolysiloxane that has a fluorine atom-containing organic group in the molecule but does not contain a hydrosilylation reactive group, and is a release control agent component that imparts excellent release properties to the film obtained by curing the silicone release agent composition. By using the above-mentioned components (A) and (C) in combination, the curable silicone composition of the present invention and the release agent layer obtained thereby not only achieve low release properties, but also achieve a sufficiently low release force for silicone pressure-sensitive adhesives for which conventional release agents have not been able to achieve sufficient release properties, particularly for silicone pressure-sensitive adhesives with a low storage modulus at low temperatures, and make it possible to maintain a uniform pressure-sensitive adhesive surface after release.

[0052] The molecular structure of component (C) is not limited, and examples include linear, branched, partially branched linear, resinous, and cyclic structures, with linear or partially branched linear structures being preferred. Such component (C) is preferably a compound represented by the following average composition formula (III): (R 3 3SiO 1 / 2 ) ba (R 3 2SiO 2 / 2 ) bb (R 3 SiO 3 / 2 ) bc (SiO 4 / 2 ) bd (III) It is desirable that the organopolysiloxane is represented by the following formula:

[0053] In formula (III), R 3 are the same or different and independently represent an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, a fluoroalkyl group having 1 to 12 carbon atoms, or a fluoro(poly)ether-containing organic group. ba is a positive number, bb is a positive number, bc is 0 or a positive number, and bd is 0 or a positive number. However, when ba is 2, the sum of ba to bd is preferably within a range of 1 to 5,000, and more preferably an integer of 30 to 3,000.

[0054] R 3The alkyl group having 1 to 12 carbon atoms that can be represented by is preferably a methyl group.

[0055] Also, R 3 The aryl group having 6 to 12 carbon atoms that can be represented by is preferably a phenyl group.

[0056] Also, R 3 Examples of the aralkyl group having 7 to 12 carbon atoms that can be represented include a benzyl group and a phenylethyl group.

[0057] Furthermore, R 3 The fluoroalkyl group having 1 to 12 carbon atoms that can be represented by R 2 The fluoroalkyl groups having 1 to 12 carbon atoms exemplified in are preferably used.

[0058] Also, R 3 The fluoro(poly)ether-containing organic group that can be represented by R 1 The fluoro(poly)ether-containing organic groups exemplified in are preferably used.

[0059] The content of fluorine atoms from the fluorine atom-containing organic groups in component (C) is preferably 20 to 40 mass%, more preferably 23 to 35 mass%, and particularly preferably 27 to 34 mass%. On the other hand, if the content of fluorine atom-containing organic groups per molecule is less than the above lower limit or exceeds the above upper limit, excellent releasability may not be obtained.

[0060] The organopolysiloxane is characterized by the content of fluorine atom-containing organic groups and the absence of hydrosilylation reactive groups in the molecule. When the organopolysiloxane contains hydrosilylation reactive groups, particularly in silicone release agent compositions that cure by hydrosilylation reactions, the organopolysiloxane is likely to form covalent bonds with the crosslinking agent or base compound in the silicone cured product that has release properties, and this may prevent the release control agent from achieving excellent release properties.

[0061] The molecular chain terminals of the organopolysiloxane are preferably trimethylsiloxy groups or silanol groups, and it is more preferable that one or more of the molecular chain terminals be trimethylsilyl groups.

[0062] Specific examples of such organopolysiloxanes include methyl(3,3,3-trifluoropropyl)polysiloxanes terminated at both molecular chain ends with trimethylsiloxy groups, methyl(3,3,3-trifluoropropyl)siloxane-dimethylsiloxane copolymers terminated at both molecular chain ends with trimethylsiloxy groups, methyl(3,3,4,4,5,5,6,6,6-nonafluorohexyl)siloxane-dimethylsiloxane copolymers terminated at both molecular chain ends with trimethylsiloxy groups, methyl(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)siloxane-dimethylsiloxane copolymers terminated at both molecular chain ends with trimethylsiloxy groups, and silanols terminated at both molecular chain ends. Examples include methyl(3,3,3-trifluoropropyl)siloxane-dimethylsiloxane copolymers capped with silanol groups at both molecular chain ends, methyl(3,3,4,4,5,5,6,6,6-nonafluorohexyl)siloxane-dimethylsiloxane copolymers capped with silanol groups at both molecular chain ends, methyl(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)siloxane-dimethylsiloxane copolymers capped with silanol groups at both molecular chain ends, and methyl(3,3,4,4,5,5,6,6,6-nonafluorohexyl)siloxane-dimethylsiloxane copolymers in which one molecular chain end is capped with a silanol group and the other end is capped with a trimethylsiloxy group.

[0063] The content of component (C) is in the range of 0.01 to 20 parts by mass, preferably 0.1 to 10 parts by mass, per 100 parts by mass of component (A). If the content of component (C) is less than 0.01 part by mass per 100 parts by mass of component (A), the easy release properties of the film (cured release film) obtained upon curing may be significantly reduced against adhesive substances. If the content of component (C) exceeds 20 parts by mass, the strength of the film obtained upon curing may be significantly reduced, making it difficult to obtain the desired release agent composition.

[0064] Furthermore, as the component (C) of the present invention, these organopolysiloxanes can be used alone or in combination of two or more.

[0065] [(D) component] Component (D) is a hydrosilylation catalyst that promotes curing of the curable silicone composition via a hydrosilylation reaction, and examples thereof include platinum catalysts, rhodium catalysts, and palladium catalysts, with platinum catalysts being preferred. Examples of platinum catalysts include platinum fine powder, platinum black, platinum-supported silica fine powder, platinum-supported activated carbon, chloroplatinic acid, alcohol solutions of chloroplatinic acid, platinum olefin complexes, and platinum alkenylsiloxane complexes.

[0066] The content of component (D) is an amount that promotes the curing of the present curable silicone composition, specifically an amount such that the metal atoms, preferably platinum atoms, in the catalyst are in the range of 0.1 to 1,000 ppm by mass relative to the present curable silicone composition. This is because if the content of component (D) is at or above the lower limit of the above range, the curing of the resulting curable silicone composition will proceed sufficiently, whereas if it is below the upper limit of the above range, the resulting cured product will be less likely to be discolored.

[0067] [(E) component] Component (E) is any organic solvent that can uniformly dissolve the fluorine-containing organopolysiloxane mixture (component (A)) and the entire composition. "Dissolved" here means that the solvent gives a homogeneous, transparent liquid at 25°C that is not turbid in appearance.

[0068] Furthermore, the addition of an organic solvent can reduce the viscosity of the curable silicone composition, improving application workability and wettability to substrates.

[0069] The component (E) is preferably one solvent or a mixed solvent of two or more solvents selected from the group consisting of 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, pentane, m-xylene hexafluoride, methyl heptafluoropropyl ether, methyl nonafluorobutyl ether, ethyl nonafluorobutyl ether, and 3-methoxy-1,1,1,2,2,3,4,4,5,5,6,6,6-tridecafluorohexane.

[0070] In addition to the organic solvents described above, other organic solvents may also be used, provided that the appearance of the curable silicone composition can be maintained as transparent and uniform at 25°C from the time the composition is prepared until it is used. Such additional organic solvents are not particularly limited, and examples thereof 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 volatiles, 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; ester solvents such as ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, and isobutyl acetate; and esters such as 2-methoxyethyl acetate, 2-ethoxyethyl acetate, propylene glycol monomethyl ether acetate, and 2-butoxyethyl acetate. and solvents having an ether moiety; siloxane-based solvents such as hexamethyldisiloxane, octamethyltrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, tris(trimethylsiloxy)methylsilane, and tetrakis(trimethylsiloxy)silane; fluorine-modified solvents other than the above-mentioned m-xylene hexafluoride, methyl heptafluoropropyl ether, methyl nonafluorobutyl ether, ethyl nonafluorobutyl ether, and 3-methoxy-1,1,1,2,2,3,4,4,5,5,6,6,6-tridecafluorohexane, for example, fluorine-modified aromatic hydrocarbon-based solvents such as benzotrifluoride, fluorine-modified ether-based solvents such as perfluoro(2-butyltetrahydrofuran), and fluorine-modified alkylamine-based solvents such as perfluorotributylamine and perfluorotripentylamine; and mixed solvents of two or more selected from these.

[0071] The content of component (E) is the amount necessary to uniformly dissolve the entire curable silicone composition, and is preferably 10,000 parts by mass or less, and more preferably within the range of 20 to 5,000 parts by mass, per 100 parts by mass of component (A).

[0072] [Component (F)] The curable silicone composition may contain (F) a hydrosilylation reaction inhibitor to inhibit the crosslinking reaction. Component (F) may be an alkyne alcohol such as 1-ethynylcyclohexane-1-ol, 2-methyl-3-butyn-2-ol, 3,5-dimethyl-1-hexyn-3-ol, or 2-phenyl-3-butyn-2-ol; an enyne compound such as 3-methyl-3-penten-1-yne or 3,5-dimethyl-3-hexen-1-yne; a methyl alkenyl compound such as 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane or 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane; or a methyl alkenyl compound such as 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane or 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane. Examples include siloxane oligomers; 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-phenylpropynoxy)silane, dimethylbis(1-methyl-1-phenylpropynoxy)silane, methyltris(1,1-dimethylpropynoxy)silane, and dimethylbis(1,1-dimethylpropynoxy)silane; and other compounds such as benzotriazole, diallyl maleate, diallyl fumarate, and (tris((1,1-dimethyl-2-propynyl)oxy)methylsilane).

[0073] There are no restrictions on the amount of component (F), and in order to provide the present curable silicone composition with a sufficient pot life, when component (F) is used, the amount thereof is preferably within a range from 0.01 to 5 parts by mass, from 0.05 to 5 parts by mass, or from 0.05 to 3 parts by mass per 100 parts by mass of component (A).

[0074] [Other additives] The curable silicone composition may contain additives selected from photopolymerization initiators, antioxidants, reactive diluents, leveling agents, fillers, antistatic agents, antifoaming agents, pigments, and the like, as long as the object of the present invention can be achieved.

[0075] [Application] The curable silicone composition of the present invention is preferably used as a release coating agent, and is suitable for use as a release coating agent for silicone pressure-sensitive adhesives. In particular, it is most suitable for use as a release coating agent for silicone pressure-sensitive adhesives with a low storage modulus at low temperatures. Specifically, it is capable of maintaining low release force and a uniform adhesive layer surface after release for silicone pressure-sensitive adhesives with a storage modulus at -20°C of 5 MPa or less, preferably 2.5 MPa or less, and more preferably 1.0 MPa or less, and therefore greatly expands the industrial applicability of silicone pressure-sensitive adhesive films / sheets, which could not be handled or worked with using conventional release agents.

[0076] The present invention also relates to a release film comprising a substrate, particularly a film-like substrate, and a release layer formed from a cured product obtained by curing the release coating agent of the present invention. Such a release film can be produced, for example, by applying the curable silicone composition of the present invention to the film-like substrate and curing the curable silicone composition. The release film of the present invention is particularly suitable for use with silicone pressure-sensitive adhesives.

[0077] The substrate used for the release film can be a film-like substrate selected from paper, plastic film, glass, metal, etc. When a product having a release layer provided on a substrate is used as a release film, the substrate is preferably a plastic film, more preferably a polyester film. In particular, it is preferable that both the substrate and the release layer are light-transmitting.

[0078] The thickness of the release layer is preferably 2.0 μm or less, 1.0 μm or less, or 0.5 μm or less, more preferably 0.4 μm or less, and even more preferably 0.3 μm or less. Also, it is preferably 0.05 μm or more, more preferably 0.1 μm or more. This is because, if the film thickness is above the lower limit of the above range, the peeling force of the resulting release layer is sufficiently low, while, if it is below the upper limit of the above range, the light transmittance of the release layer is particularly excellent.

[0079] [Laminate] The present invention also relates to a laminate including at least a release layer made of a cured product obtained by curing the curable silicone composition of the present invention and a pressure-sensitive adhesive layer, particularly a silicone pressure-sensitive adhesive layer, disposed opposite the release layer. In this case, the curable silicone composition can also be referred to as a release coating agent. In this case, the term "opposite" means that the release layer and the pressure-sensitive adhesive layer are in direct contact. Therefore, in general, in the present invention, the release layer and the pressure-sensitive adhesive layer are disposed opposite each other. In the following description, the structure of the laminate of the present invention will be described using a silicone pressure-sensitive adhesive as an example of the pressure-sensitive adhesive, but the pressure-sensitive adhesive is not limited to a silicone pressure-sensitive adhesive.

[0080] The laminate of the present invention may have any structure as long as it includes the above-mentioned structure in which the release layer and the silicone pressure-sensitive adhesive layer are disposed facing each other. Specific examples of laminates are described below.

[0081] Examples of the configuration of the laminate of the present invention include the following (a) to (d). These specific configurations are the same as those disclosed by the present applicant in, for example, Patent Document 6 and Patent Document 7, except that the release layer is replaced with a cured layer obtained by curing the curable silicone composition of the present invention, and preferably the silicone pressure-sensitive adhesive layer has a storage modulus at -20°C of 5 MPa or less. (a) a structure consisting of a first substrate / a release layer / a silicone adhesive layer / a second substrate; (b) A structure in which two or more structural units each consisting of a substrate / release layer / silicone adhesive layer are stacked in succession; (c) a structure consisting of a first substrate / a first release layer / a silicone adhesive layer / a second release layer / a second substrate; (d) A structure in which two or more structural units each consisting of a substrate / first release layer / silicone adhesive layer / second release layer are stacked in succession. In the structures (b) and (d), the substrate can be discontinuous or continuous. Generally, when the substrate is discontinuous, the laminate is in the form of a sheet, and when a continuous substrate is used, the laminate is in the form of a roll.

[0082] Such a substrate is preferably in the form of a sheet or film, and is particularly preferably in the form of a film, and the same substrate as that used for the release film can be used. The substrate may be either light-transmitting or light-non-transmitting, and when a plurality of substrates are used, they may be arbitrarily combined depending on the purpose.

[0083] The laminate of the present invention may be in the form of a laminated sheet in which multiple sheet-like members, each consisting of a substrate / release layer / silicone pressure-sensitive adhesive layer, are stacked vertically, or may be in the form of a roll, for example, wound around a suitable cylindrical or tubular core.

[0084] In the laminate of the present invention, when a first release layer is arranged facing one of the two surfaces of a silicone adhesive layer and a second release layer is arranged facing the other surface (e.g., corresponding to structure (c) or (d)), at least one of the first release layer and the second release layer must be a release layer made of a cured product obtained by curing the release coating agent of the present invention, and here, it is preferable that the peel force (F1) when peeling the silicone adhesive from the first release layer is different from the peel force (F2) when peeling the silicone adhesive from the second release layer.

[0085] If the difference in peel strength between F1 and F2 is small, after the operation of peeling one release layer from the silicone adhesive layer (peeling of the first opposing surface), when peeling the other release layer (second opposing surface), the second opposing surface may unintentionally peel partially during peeling of the first opposing surface, destroying the silicone adhesive layer and making it difficult to use it as an adhesive as originally intended. The peel force difference is preferably, for example, 10 gf / inch or more, and more preferably 20 gf / inch or more.

[0086] Methods for realizing the above-mentioned difference in peeling force include selecting a method for forming the opposing surfaces as described below, and using different types of two release layers.

[0087] In the laminate of the present invention, the thickness of the release layer is preferably 2.0 μm, 1.0 μm, or 0.5 μm or less, more preferably 0.4 μm or less, and even more preferably 0.3 μm or less. Also, it is preferably 0.05 μm or more, more preferably 0.1 μm or more. This is because, when the film thickness of the release layer is above the lower limit of the aforementioned range, the peel strength of the release layer from the silicone pressure-sensitive adhesive is sufficiently low, while, when the film thickness is below the upper limit of the aforementioned range, the light transmittance of the release layer is particularly excellent and it is also economical.

[0088] The silicone pressure-sensitive adhesive composition or curable silicone pressure-sensitive adhesive composition that can be used in the laminate of the present invention is not limited to any particular one, and any composition that is suitable for the intended use of the laminate, such as use as a pressure-sensitive adhesive tape, can be used. In particular, silicone pressure-sensitive adhesives that have a low storage modulus at low temperatures are preferably used.

[0089] There are no particular restrictions on the curing mechanism of the curable silicone pressure-sensitive adhesive, and hydrosilylation-curable, peroxide-curable, photocurable, or other types may be used. However, hydrosilylation-curable pressure-sensitive adhesives are preferred because they can be cured at relatively low temperatures, minimizing the thermal impact on the substrate or applied materials, while also being economical in terms of process simplicity.

[0090] Furthermore, it is extremely useful for the release layer of the present invention to be applied to a silicone pressure-sensitive adhesive with a low storage modulus at low temperatures. 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 that can be designed so that the glass transition temperature of the cured pressure-sensitive adhesive composition is low, for example, below room temperature, and that has a low storage modulus at low temperatures and a sufficiently large elongation at break. For example, a silicone pressure-sensitive adhesive layer having a storage modulus of 5 MPa or less, preferably 2.5 MPa or less, and more preferably 1.0 MPa or less at -20°C, obtained by curing the silicone pressure-sensitive adhesive composition proposed by the applicant in International Publication Nos. 2017 / 188308, 2020 / 32285, and 2020 / 32286, etc., can be particularly suitably used in the present invention. Here, the release layer of the present invention is preferably applied to silicone adhesives with a low storage modulus at low temperatures, but this does not preclude its application to silicone adhesives with a high storage modulus at low temperatures, and it is possible to maintain a sufficiently reduced peel force against silicone adhesives and a uniform adhesive layer surface after peeling.

[0091] There are no particular limitations on the thickness of the silicone pressure-sensitive adhesive layer of the laminate of the present invention, but it is preferably 0.1 to 300 μm, and more preferably 0.5 to 200 μm.

[0092] Furthermore, in the laminate of the present invention, the silicone pressure-sensitive adhesive layer can be formed on the entire surface that constitutes the layer, or can be formed only on a part of the surface.The form in which the silicone pressure-sensitive adhesive layer is formed only on a part of the surface is not particularly limited, and the silicone pressure-sensitive adhesive can be applied to form, for example, one or more dots, one or more straight or curved lines, concentric circles, or any other arbitrary shape.The release layer can also be formed on the entire surface that constitutes the release layer, or it can be formed to match the shape formed by the silicone pressure-sensitive adhesive formed on the silicone pressure-sensitive adhesive layer.

[0093] [Method of manufacturing laminate] The method for producing the laminate of the present invention is not particularly limited, but some preferred methods will be listed below. First, in producing the laminate of the present invention, the following two methods are exemplified as methods for preparing the opposing surfaces of the silicone adhesive layer and the release layer.

[0094] <Method for preparing the opposing surfaces of the silicone adhesive layer and the release layer (1)> The first method for preparing the opposing surfaces is as follows: a step (1) of applying a release coating agent comprising the curable silicone composition of the present invention to a film-like substrate and curing the coating agent to form a first release film having a first release layer; Step (2) of applying a curable silicone pressure-sensitive adhesive composition to the same film substrate as the film substrate or a second film substrate different from the film substrate and curing the composition to form a silicone pressure-sensitive adhesive layer; and Step (3) of laminating the release layer of the first release film obtained in step (1) above onto the silicone pressure-sensitive adhesive layer obtained in step (2); This preparation method involves bringing an already cured release layer into contact with an already cured silicone pressure-sensitive adhesive layer to form opposing surfaces of the two layers.

[0095] <Method for preparing the opposing surfaces of the silicone adhesive layer and the release layer (2)> The second method for preparing the opposing surfaces is as follows: a step (1) of applying a release coating agent comprising the curable silicone composition of the present invention to a film-like substrate and curing the coating agent to form a first release film having a first release layer; Step (2) of applying a curable silicone pressure-sensitive adhesive composition to the first release film obtained in step (1) and curing the composition to form a silicone pressure-sensitive adhesive layer; and Step (3) of laminating a film-like substrate identical to the film-like substrate or a film-like substrate different from the film-like substrate onto the silicone pressure-sensitive adhesive layer obtained in step (2). This preparation method involves coating a curable silicone adhesive onto an already cured release layer, followed by curing to form opposing surfaces of the two layers. Generally, the second method often results in a larger difference in release force between the silicone pressure-sensitive adhesive and the release agent than the first method.

[0096] The laminate configuration examples (a) to (d) described above can be produced by, for example, the same production method as that disclosed by the applicant in the aforementioned Patent Document 5. In this case, the release layer can be replaced with a cured layer obtained by curing the curable silicone composition of the present invention, and the silicone pressure-sensitive adhesive layer can preferably have a storage modulus at −20° C. of 5 MPa or less, preferably 2.5 MPa or less, and more preferably 1.0 MPa or less. The opposing surfaces of the silicone pressure-sensitive adhesive and the release agent can be prepared by a method corresponding to the aforementioned opposing surface preparation method (1) or (2), as appropriate. [Example]

[0097] The curable silicone composition and release film of the present invention will be described in detail using examples, but the present invention is not limited to these examples in any way. In the average composition formula shown below, the symbol Me represents a methyl group, and Vi represents a vinyl group. The method for measuring the peel force when peeling the silicone pressure-sensitive adhesive from the release film is as follows.

[0098] Reference Example 1 Preparation of "Hydrosilylation-curable Silicone Pressure-Sensitive Adhesive Composition Solution 1" 36.4 parts by weight of vinyl-functional polydimethylsiloxane (gum-like (plasticity index 152), vinyl content 0.013% by weight), (CH3)3SiO 1 / 2 Units and SiO 4 / 2A homogeneous solution was prepared by thoroughly mixing 84.3 parts by weight of an MQ silicone resin (molecular weight 3300, hydroxyl group content 3.5 mol% (0.8 mass%) xylene solution (solids content 75.5%) consisting of methylsiloxane units and hydroxyl groups, 101.6 parts by weight toluene, 0.807 parts by weight of a dimethylsiloxane-methylhydrogensiloxane copolymer (molecular weight 1600, SiH content 0.73%) terminated at both molecular chain ends with trimethylsiloxy groups, and 0.577 parts by weight of 1-ethynyl-1-cyclohexanol (20% toluene solution) at room temperature. 0.484 parts by weight of a platinum-based hydrosilylation catalyst (containing 0.62 mass% platinum) was then thoroughly mixed with the mixture. The molar ratio of SiH groups in the dimethylsiloxane-methylhydrogensiloxane copolymer, in which both ends of the molecular chain are capped with trimethylsiloxy groups, to the amount of alkenyl groups in the vinyl-functional polydimethylsiloxane (SiH / Vi ratio) was 33.7, and the platinum metal content relative to the solid content was 30 ppm.

[0099] Reference Example 2: Measurement of adhesive strength of "Hydrosilylation-curable silicone adhesive composition solution 1" The "Hydrosilylation-Curable Silicone Pressure-Sensitive Adhesive Composition Solution 1" from the Reference Example was applied to a polyethylene terephthalate (PET) film (manufactured by Toray Industries, Inc., product name: Lumirror® S10, thickness: 50 μm) using an applicator to a thickness of 50 μm after curing. The applied film was then heated at 150°C for 3 minutes to form a silicone pressure-sensitive adhesive layer. After leaving the sample for 1 day, the sample was cut into 20 mm wide pieces, and the adhesive layer surface was attached to a PMMA plate (manufactured by Partec, Acrylite L001, 50 x 120 x 2 mm) using a roller to prepare a test specimen. The adhesive strength of the PMMA plate test specimen was measured using an Orientec RTC-1210 tensile tester at a 180° peel test speed of 300 mm / min in accordance with JIS Z0237 (measured at a 20 mm wide width and converted to gf / inch). The result was 1490 gf / inch.

[0100] Reference Example 3: Measurement of storage modulus of "Hydrosilylation-curable silicone pressure-sensitive adhesive composition solution 1" The "Hydrosilylation-curable Silicone Pressure-Sensitive Adhesive Composition Solution 1" from the above Reference Example was applied to a release liner coated with a fluoro-modified organopolysiloxane release agent using an applicator so that the cured film would have a thickness of 100 μm. The applied layer was then heated to 150°C for 3 minutes to cure, forming a silicone pressure-sensitive adhesive layer. Five or more of these pressure-sensitive adhesive layers were stacked to obtain a film sample with a thickness of 500 μm or more, sandwiched between release liners on both sides. An 8 mm diameter section was cut out from the film and attached to the parallel plate probe of a dynamic viscoelasticity analyzer (Anoton Paar, MCR301). The storage modulus at -20°C was measured, finding a value of 0.52 MPa. The measurement temperature ranged from -70°C to 200°C, with a frequency of 1 Hz and a heating rate of 3°C / min.

[0101] <Method for measuring peel strength> A curable silicone release agent composition was applied to a polyethylene terephthalate (hereinafter abbreviated as PET) film (manufactured by Toray Industries, Inc., product name: Lumirror (registered trademark) S10, thickness 50 μm) using a Mayer bar so that the release agent layer would be 0.2 μm thick after curing, and the mixture was heated at 150°C for 3 minutes to prepare a "release film" with a cured silicone release layer. The "hydrosilylation-curable silicone pressure-sensitive adhesive composition solution 1" from the above Reference Example was applied to the release layer of the "release film" using an applicator so that the film would be 50 μm thick after curing, and the mixture was heated at 150°C for 3 minutes to cure, forming a silicone pressure-sensitive adhesive layer. The PET film was then laminated to the resulting silicone pressure-sensitive adhesive layer using a 2 kg hand roller. The obtained film was cut into 1-inch widths, and the "Release Film 1" was pulled in a 180° direction at a rate of 0.3 m / min using a tensile tester (RTC-1210 manufactured by Orientec Co., Ltd.), and the force (peel force) required to peel the "Release Film" from the silicone adhesive layer at 25°C was measured.

[0102] <Surface condition of silicone pressure-sensitive adhesive layer after peeling off release liner> After measuring the peel strength, the surface condition of the silicone pressure-sensitive adhesive layer after the release liner was removed was visually observed, and the results were defined as follows: ○: The adhesive surface is uniform and free of roughness or wrinkles ×: Roughness and / or wrinkles occurred on the adhesive surface

[0103] [Examples 1 to 4] and [Comparative Examples 1 to 3] The curable silicone compositions of Examples 1 to 4 and Comparative Examples 1 to 3 were prepared by uniformly mixing the following components according to the formulations shown in Table 1. In the formulas, Me, Vi, and Pf represent a methyl group, a vinyl group, and a 3,3,4,4,5,5,6,6,6-nonafluorohexyl (C4F9CH2CH2) group, respectively.

[0104] (A1): Fluoroalkyl and alkenyl group-containing organopolysiloxane having a fluorine atom content of 40% by mass or more Average formula: (MeSiO 1 / 2 )2(Me2SiO 2 / 2 ) 1470 (MePfSiO 2 / 2 ) 1100 (MeViSiO 2 / 2 ) 10 The vinyl group content is 0.060 mass%, (MePfSiO 2 / 2 ) units account for 43 mol % of all diorganosiloxane units (D units) and the fluorine content is 42 mass %. (A2): Fluoroalkyl and alkenyl group-containing organopolysiloxane having a fluorine atom content of less than 40% by mass Average formula: (Me2ViSiO 1 / 2 )2(Me2SiO 2 / 2 ) 900 (Me(Pf)SiO 2 / 2 ) 450 (MeViSiO 2 / 2 ) 10 The vinyl group content is 0.16 mass%, (Me(Pf)SiO 2 / 2) units account for 33 mol % of all diorganosiloxane units (D units), and the fluorine atom content is 38 mass %. (B) Average composition formula: (MeSiO 1 / 2 )2(MePfSiO 2 / 2 ) 12 (MeHSiO 2 / 2 ) 27 and having a fluorine atom content of 38 mass % and a silicon-bonded hydrogen atom content of 0.50 mass %. (C) Average composition formula: (MeSiO 1 / 2 )2(Me2SiO 2 / 2 ) 900 (MePfSiO 2 / 2 ) 300 and the fluorine atom content is 32 mass %. (D) 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex (in an amount such that the amount of platinum metal was 270 ppm relative to the amount of solids in the curable composition) was used. (E) Diisopropyl ether (F) 2-Methyl-3-butyn-2-ol

[0105] [Mixed Test] The above (A1) and (A2) were placed in a 1:1 mass ratio in a transparent glass vial with a lid and thoroughly stirred and mixed at 25°C. The mixture became cloudy and did not become uniformly transparent. This mixture was left to stand at 25°C, and when the appearance was observed again after 24 hours, it remained cloudy. Note that (A1) and (A2) are both clear liquids at 25°C.

[0106] A curable silicone composition was prepared according to the formulation shown in Table 1 below, and a release film was prepared using this as a release coating agent according to the method described above. The peel force when peeling the release film from the silicone pressure-sensitive adhesive layer was measured. In addition, the surface condition of the silicone pressure-sensitive adhesive layer after peeling the release film was visually observed.

[0107] [Table 1]

[0108] As mentioned above, the release layer of the present invention is suitable for use with silicone adhesives that have a low storage modulus at low temperatures, but it can also be applied to silicone adhesives that have a high storage modulus at low temperatures, as shown in Reference Examples 4 to 7.

[0109] Reference Example 4: Preparation of "Hydrosilylation-curable Silicone Pressure-Sensitive Adhesive Composition Solution 2" A homogeneous solution was prepared by thoroughly mixing 100.0 parts by mass of the hydrosilylation-curable adhesive DOWSIL™ 7657 ADHESIVE (solids content 56% by mass) manufactured by The Dow Chemical Company, 0.42 parts by mass of 4000 CATALYST (platinum metal-containing hydrosilylation reaction catalyst) manufactured by the same company, and 33.3 parts by mass of toluene.

[0110] Reference Example 5: Measurement of adhesive strength of "Hydrosilylation-curable silicone adhesive composition solution 2" The adhesive strength was measured in the same manner as in Reference Example 2 above, except that "hydrosilylation-curable silicone pressure-sensitive adhesive composition solution 1" was replaced with "hydrosilylation-curable silicone pressure-sensitive adhesive composition solution 2" and the heat curing conditions were changed from 150°C for 3 minutes to 140°C for 5 minutes. The result was 1450 gf / inch.

[0111] Reference Example 6: Measurement of storage modulus of "Hydrosilylation-curable silicone pressure-sensitive adhesive composition solution 2" In the same manner as in Reference Example 3 above, "hydrosilylation-curable silicone pressure-sensitive adhesive composition solution 1" was changed to "hydrosilylation-curable silicone pressure-sensitive adhesive composition solution 2," and the heat curing conditions were changed from 150°C for 3 minutes to 140°C for 5 minutes. The storage modulus at -20°C was measured and found to be 9.5 MPa.

[0112] <Reference Examples 7-1, 7-2> Curable silicone compositions were prepared according to the compositions shown in Table 2 below, the same composition as in Example 3, and a composition (Example 3') in which the amount of component (C) was changed to 0.5 parts by mass. Using these as release coating agents, release films were prepared according to the method described above, and the peel force when peeling the release film from the silicone pressure-sensitive adhesive layer was measured. In addition, the surface condition of the silicone pressure-sensitive adhesive layer after peeling the release film was visually observed. The results are shown in Table 2.

[0113] [Table 2]

[0114] [Summary] The curable silicone compositions of Examples 1 to 4 according to the present invention achieved much lower release forces than those of Comparative Examples 1 to 3. Furthermore, after the release liners made of the curable compositions of Examples 1 to 4 were removed, the surface of the silicone pressure-sensitive adhesive layer was uniform, with no roughness or wrinkles observed. In contrast, when component (A) was used alone, or when component (C) was not used, a sufficient reduction in release force could not be achieved for silicone pressure-sensitive adhesives with low storage moduli at low temperatures. In particular, the silicone pressure-sensitive adhesive layer remained non-uniform after removal, raising serious concerns that this could limit the scope of industrial use. (Comparative Examples 1 to 3) As confirmed in Reference Examples 7-1 and 7-2, the curable silicone compositions according to the present invention are also suitable for use with silicone pressure-sensitive adhesives with a low-temperature storage modulus of more than 5 MPa. [Industrial Applicability]

[0115] As shown in the examples, a release film equipped with a release layer formed using the curable silicone composition of the present invention as a release coating agent for silicone pressure-sensitive adhesives can release silicone pressure-sensitive adhesives, particularly those with a low storage modulus at low temperatures, with little force, and can maintain a uniform surface of the silicone pressure-sensitive adhesive after the release film has been removed, preventing roughness and wrinkles. Therefore, the curable silicone composition of the present invention is useful not only for conventional commercially available silicone pressure-sensitive adhesives, but also as a release coating agent for release films for silicone pressure-sensitive adhesives with a low storage modulus at low temperatures. Furthermore, despite their excellent performance, silicone pressure-sensitive adhesives with a low storage modulus at low temperatures have tended to have limited application because there are few release agents that are compatible with them. However, the availability of the release coating agent of the present invention makes it easy to provide silicone pressure-sensitive adhesive films / sheets with good release properties and low release properties, and it is strongly expected that their industrial application will expand.

Claims

1. (A) A mixture of two or more types of fluoroalkyl group-containing organopolysiloxanes each having a fluoroalkyl group and at least two alkenyl groups in one molecule, with the fluoroalkyl group contents being different from one another, wherein the two or more types of fluoroalkyl group-containing organopolysiloxanes are not completely miscible at 25°C when mixed without a solvent. (B) an organohydrogenpolysiloxane having at least three silicon-bonded hydrogen atoms in each molecule; (C) an organopolysiloxane having a fluorine atom-containing organic group and not containing a hydrosilylation reactive group; (D) a hydrosilylation catalyst, and (E) Organic Solvent A release coating agent for silicone pressure-sensitive adhesives, which comprises a curable silicone composition containing the compound (I) and has a storage modulus at -20°C of 1.0 MPa or less.

2. The component (A) is (A1) one or more linear or branched organopolysiloxanes containing fluoroalkyl group-containing organodisiloxane units and having a fluorine atom content of 40% by mass or more; and (A2) One or more linear or branched organopolysiloxanes containing fluoroalkyl group-containing organodisiloxane units and having a fluorine atom content of less than 40% by mass 2. The release coating agent for silicone pressure-sensitive adhesives according to claim 1, which is a mixture of

3. 3. The release coating agent for silicone pressure-sensitive adhesives according to claim 2, wherein the difference between the fluorine atom content (% by mass) of component (A1) and the fluorine atom content (% by mass) of component (A2) is 3% by mass or more.

4. The component (A) is (A1) one or more linear or branched organopolysiloxanes containing fluoroalkyl group-containing organodisiloxane units, the fluoroalkyl groups being 3,3,4,4,5,5,6,6,6-nonafluorohexyl groups, and the units accounting for 39 mol % or more of all organosiloxane units; and (A2) One or more linear or branched organopolysiloxanes containing fluoroalkyl group-containing organodisiloxane units, the fluoroalkyl groups being 3,3,4,4,5,5,6,6,6-nonafluorohexyl groups, and the units accounting for 36 mol % or less of all organosiloxane units. The release coating agent for silicone pressure-sensitive adhesives according to any one of claims 1 to 3, which is a mixture of

5. 5. The release coating agent for silicone pressure-sensitive adhesives according to claim 4, wherein the mass ratio of the components (A1) and (A2) is (A1) / (A2) = 1 / 99 to 99 / 1.

6. The component (C) has a trimethylsilyl group at one or more of its molecular chain terminals, the fluorine atom-containing organic group is one or more groups selected from a fluoroalkyl group having 1 to 12 carbon atoms and a fluoro(poly)ether-containing organic group, 6. The release coating agent for silicone pressure-sensitive adhesives according to any one of claims 1 to 5, which is an organopolysiloxane in which the content of fluorine atoms due to fluorine atom-containing organic groups in the molecule is in the range of 20 to 40 mass%.

7. 7. The release coating agent for silicone pressure-sensitive adhesives according to any one of claims 1 to 6, wherein component (B) is an organohydrogenpolysiloxane further having a fluoroalkyl group having 1 to 12 carbon atoms or a fluoro(poly)ether-containing organic group.

8. 8. A release coating agent for silicone pressure-sensitive adhesives according to any one of claims 1 to 7, comprising, per 100 parts by mass of component (A), 0.1 to 40 parts by mass of component (B), 0.01 to 20 parts by mass of component (C), a quantity of component (D) such that the platinum metal content is 0.1 to 500 ppm, and 20 to 10,000 parts by mass of component (E).

9. a film-like substrate, and A release layer comprising a cured product obtained by curing the release coating agent for silicone pressure-sensitive adhesives according to any one of claims 1 to 8. Including a release film.

10. A laminate having a structure in which a silicone adhesive layer having a storage modulus of 1.0 MPa or less at -20°C is arranged opposite at least one release layer, the release layer being a release layer made of a cured product obtained by curing a release coating agent for silicone adhesives described in any one of claims 1 to 8.

11. The laminate according to claim 10, wherein the entire laminate is in at least one shape selected from i) a laminated sheet and ii) a roll.

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