Release control agent, silicone composition for forming release coating, and release liner

Abstract

The present invention relates to: a release control agent comprising a silicone resin represented by the average unit formula (R1 3SiO1 / 2 a(SiO4 / 2 1.0 (in the formula, each R1 independently is a C1-6 alkyl group and a is a number of 0.5-1.5.) and having a weight average molecular weight in terms of standard polystyrene by gel permeation chromatography of 3,000-6,000, and (B) a diorganopolysiloxane having at least two silicon atom-bonded alkenyl groups per molecule and / or (C) a C12-24 α-olefin; and a silicone composition for forming a releaseable film including the same. This silicone composition for forming a releaseable film forms a releaseable film that, although exhibiting relatively large release force relative to an adhesive, undergoes little change in release force after long-term aging with an adhesive adhered and does not lower the residual adhesive strength of an adhesive.

Description

[Technical Field]

[0001] The present invention relates to a release control agent, a silicone composition for forming a release coating containing the same, and a release liner having a release coating formed thereon from the composition. [Background technology]

[0002] Silicone compositions for forming release coatings can be applied to the surface of various substrates such as paper, synthetic resin film, etc., and then cured to form a coating that exhibits release properties against pressure-sensitive adhesives. Such release coatings are required to have a consistent release force when peeling off the pressure-sensitive adhesive, and to maintain their residual adhesive strength even after the pressure-sensitive adhesive has been left in contact with the substrate for an extended period of time.

[0003] On the other hand, in order to make the release coating for the pressure sensitive adhesive strong release (requiring a large force to release), a silicone resin is generally blended as a release control agent. For example, Patent Document 1 discloses R3SiO 1 / 2 units (where R is the same or different monovalent hydrocarbon group having two or fewer carbon atoms) and SiO 4 / 2 The silicone resin consisting of units may be optionally mixed with dibutyl maleate, decyl vinyl ether, dodecyl vinyl ether, camphene, C 16-18 It has been proposed to compound a curable silicone composition comprising an alkenyl-containing diorganopolysiloxane, a methylhydrogenpolysiloxane having silicon-bonded hydrogen atoms, and a hydrosilylation catalyst together with a reactive diluent selected from the group consisting of -α-olefins and m-bisisopropenylbenzene. Patent Document 2 also proposes compounding a diorganopolysiloxane having at least two alkenyl groups per molecule, an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms per molecule, and a compound of the formula: (CH3)3SiO 0.5 and a solvent-soluble silicone resin comprising siloxane units represented by the formula: (CH3)3SiO 0.5 , (CH3)2(CH2=CH)SiO 0.5Patent Document 3 also proposes a silicone composition for forming a release coating, which comprises a mixture of a solvent-soluble silicone resin consisting of siloxane units represented by the general formula: SiO2 and R'3SiO2, and a catalyst for addition reaction. 1 / 2 R' is a monovalent hydrocarbon group having up to 3 carbon atoms, a hydrogen atom, an alkenyl group, or an oxyalkenyl group, and at least one R' in one molecule is the alkenyl group or the oxyalkenyl group, and the R'3SiO 1 / 2 A silicone composition for forming a release coating has been proposed, which comprises a silicone resin in which 50% or less of the units have the alkenyl group or oxyalkenyl group, an organopolysiloxane having at least three silicon-bonded hydrogen atoms per molecule, and a hydrosilylation catalyst, and optionally contains an organopolysiloxane having at least two alkenyl groups per molecule.

[0004] However, with release coatings formed from the above-mentioned silicone compositions for forming release coatings, it is difficult to achieve a sufficiently strong release force, and there are problems such as changes in release force and a decrease in the residual adhesive strength of the adhesive after the adhesive has been in close contact for an extended period of time. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 59-084953 [Patent Document 2] Japanese Patent Application Publication No. 01-215857 [Patent Document 3] Japanese Patent Application Publication No. 07-252360 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a release control agent for forming a release coating which, despite exhibiting a relatively high release force against a pressure-sensitive adhesive, shows only a small change in release force after long-term aging in a state in which the pressure-sensitive adhesive is adhered, and which does not reduce the residual adhesive strength of the pressure-sensitive adhesive. Another object of the present invention is to provide a release coating-forming silicone composition which is capable of forming such a release coating, and a release liner in which a release coating has been formed from said composition. [Means for solving the problem]

[0007] The peeling control agent of the present invention comprises (A) Average unit formula: (R 1 3SiO 1 / 2 ) a (SiO 4 / 2 ) 1.0 (In the formula, each R 1 are independently an alkyl group having 1 to 6 carbon atoms, and a is a number from 0.5 to 1.5. and a weight average molecular weight of 3,000 to 6,000 in terms of standard polystyrene as determined by gel permeation chromatography. (B) a diorganopolysiloxane having at least two silicon-bonded alkenyl groups per molecule, in an amount of 0 to 150 parts by mass per 100 parts by mass of component (A), and (C) α-olefin having 12 to 24 carbon atoms, 0 to 200 parts by mass per 100 parts by mass of component (A) and characterized in that it contains at least one of the above component (B) and the above component (C).

[0008] In the release control agent, the component (A) is preferably a silicone resin containing 2 to 5 mass % of hydroxyl groups bonded to silicon atoms.

[0009] In the release control agent, the component (C) is preferably an α-olefin having 12 to 18 carbon atoms.

[0010] The release control agent further contains at most 300 parts by mass of (D) an average unit formula: (R 2 3SiO 1 / 2 ) b (SiO 4 / 2 ) 1.0 (In the formula, each R 2 are independently an alkyl group having 1 to 6 carbon atoms or an alkenyl group having 2 to 6 carbon atoms, provided that at least one R 2 is the alkenyl group, and b is a number from 0.5 to 1.5. It is preferable that the silicone resin contains a silicone resin represented by the formula:

[0011] The release coating-forming silicone composition of the present invention comprises: (I) the above-mentioned peeling control agent, (II) a diorganopolysiloxane having at least two silicon-bonded alkenyl groups per molecule; at most 400 parts by mass of component (I) per 100 parts by mass of components (A), (B), and (C) combined; (III) an organopolysiloxane having at least two silicon-bonded hydrogen atoms per molecule, in an amount such that there are 0.5 to 10 moles of silicon-bonded hydrogen atoms in this component per mole of total alkenyl groups in the composition; and (IV) Hydrosilylation reaction catalyst The present invention is characterized in that it comprises:

[0012] The composition preferably further contains (V) a hydrosilylation reaction inhibitor in an amount that accounts for 0.001 to 5% by mass of the composition.

[0013] The composition further comprises (VI) an average unit formula: (R 2 3SiO 1 / 2 ) b (SiO 4 / 2 ) 1.0 (In the formula, each R 2are independently an alkyl group having 1 to 6 carbon atoms or an alkenyl group having 2 to 6 carbon atoms, provided that at least one R 2 is the alkenyl group, and b is a number from 0.5 to 1.5. It is preferable that the silicone resin represented by the following formula be contained in an amount of at most 50 parts by mass per 100 parts by mass of the total of components (A), (B), and (C) in component (I).

[0014] The release liner of the present invention is characterized by having a release coating formed on the surface of a film- or tape-like substrate from the above-described silicone composition for forming release coatings. [Effects of the Invention]

[0015] By incorporating the release control agent of the present invention into a silicone composition for forming a release coating, it is possible to form a release coating that exhibits a relatively high release force against a pressure-sensitive adhesive, yet shows little change in release force after long-term aging with the pressure-sensitive adhesive adhered to it, and does not reduce the residual adhesive force of the pressure-sensitive adhesive. The silicone composition for forming a release coating of the present invention is also capable of forming the release coating described above. Furthermore, because the release liner of the present invention contains the release coating described above, it is characterized by the fact that, despite showing a relatively high release force against a pressure-sensitive adhesive, shows little change in release force after long-term aging with the pressure-sensitive adhesive adhered to it, and does not reduce the residual adhesive force of the pressure-sensitive adhesive. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view of a release liner of the present invention. [Figure 2] 1 is a cross-sectional view showing a state in which a pressure-sensitive adhesive is laminated on a release liner of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] <Terminology> In this specification, the "weight average molecular weight" refers to a value calculated using standard polystyrene as determined by gel permeation chromatography. The gel permeation chromatography was performed using a Waters Alliance e2695 Separations Module as the measuring device, two Tosoh TSKgel Multipore HXL-M columns, toluene as the eluent, and standard polystyrenes covering the molecular weight range of 590 to 6,770,000.

[0018] <Peeling control agent> The peeling control agent of the present invention comprises (A) Average unit formula: (R 1 3SiO 1 / 2 ) a (SiO 4 / 2 ) 1.0 Silicone resins represented by the formula: (B) Diorganopolysiloxane having at least two silicon-bonded alkenyl groups per molecule Consists of The above component (A), and (C) α-olefins having 12 to 24 carbon atoms or Components (A) to (C) It consists of:

[0019] Component (A) is the main component of the release control agent and is a silicone resin represented by the above average unit formula. 1 are independently an alkyl group having 1 to 6 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group, and preferably a methyl group.

[0020] In the formula, a represents the formula: SiO 4 / 2 For siloxane units represented by the formula: R 1 3SiO 1 / 2is a number in the range of 0.5 to 1.5, and preferably a number in the range of 0.6 to 1.2, or a number in the range of 0.6 to 1.0. This is because when a is at or above the lower limit of the above range, the coatability of the silicone composition for forming a release coating containing this is improved, while when it is below the upper limit of the above range, the resulting release coating can have heavy release properties.

[0021] The weight-average molecular weight of such silicone resins, measured by gel permeation chromatography in terms of standard polystyrene, is in the range of 3,000 to 6,000, and preferably in the range of 3,000 to 5,000, 4,000 to 6,000, or 4,000 to 5,000. This is because when the weight-average molecular weight of the silicone resin is at or above the lower limit of this range, the resulting release coating can have strong release properties, while when it is at or below the upper limit of this range, the coatability of the silicone composition for forming a release coating containing it is improved.

[0022] Furthermore, such silicone resins preferably have hydroxyl groups bonded to silicon atoms in the molecule, and the content of these hydroxyl groups bonded to silicon atoms is preferably within the range of 2 to 5 mass%, 2 to 4 mass%, 2.5 to 4 mass%, or 2.5 to 3.5 mass%. This is because when the content of silicon-bonded hydroxyl groups in the silicone resin is within the above range, they contribute to the curing reaction of the release coating-forming silicone composition, and can improve the residual adhesion rate of the pressure-sensitive adhesive when the resulting release liner is used.

[0023] Component (B) is a dispersant for component (A) and is a diorganopolysiloxane containing at least two silicon-bonded alkenyl groups per molecule. Examples of the alkenyl groups in component (B) include alkenyl groups having 2 to 6 carbon atoms, such as vinyl, allyl, butenyl, pentenyl, and hexenyl, with vinyl and hexenyl being preferred. Examples of groups bonded to silicon atoms other than alkenyl groups in component (B) include alkyl groups having 1 to 6 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, and hexyl; aryl groups having 6 to 12 carbon atoms, such as phenyl, tolyl, and xylyl; and halogen-substituted alkyl groups having 1 to 6 carbon atoms, such as 3,3,3-trifluoropropyl, with methyl being preferred. Furthermore, small amounts of hydroxyl groups or alkoxy groups having 1 to 3 carbon atoms, such as methoxy groups and ethoxy groups, may be bonded to silicon atoms in component (B), provided that the object of the present invention is not impaired.

[0024] The molecular structure of component (B) is not limited, and examples include linear and partially branched linear structures. The viscosity of component (B) at 25°C is also not limited, and components ranging from low viscosity to high viscosity gum-like components can be used. However, since this provides good dispersibility for the release control agent, the viscosity is preferably in the range of 10 to 1,000 mPa·s or 10 to 500 mPa·s. The viscosity of component (B) at 25°C can be measured using a rotational viscometer in accordance with JIS K7117-1.

[0025] Examples of such component (B) include dimethylpolysiloxanes terminally capped with dimethylvinylsiloxy groups, dimethylsiloxane-methylvinylsiloxane copolymers terminally capped with dimethylvinylsiloxy groups, partially branched dimethylpolysiloxanes terminally capped with dimethylvinylsiloxy groups, partially branched dimethylpolysiloxanes terminally capped with dimethylvinylsiloxy groups and the other terminals capped with trimethylsiloxy groups, dimethylsiloxane-methylvinylsiloxane copolymers terminally capped with trimethylsiloxy groups, methylvinylsiloxane-methyl(3,3,3-trifluoropropyl)siloxane copolymers terminally capped with trimethylsiloxy groups, and dimethylsiloxane-methylvinylsiloxane copolymers terminally capped with silanol groups.

[0026] In the present release control agent, the inclusion of component (B) is optional; however, if component (C) is not included, component (B) is essential. The content of component (B) in the present release control agent is within the range of 0 to 150 parts by mass, preferably 10 to 150 parts by mass, or 20 to 100 parts by mass, per 100 parts by mass of component (A). This is because, when the content of component (B) is at or above the lower limit of the above range, the viscosity of the resulting release control agent can be reduced, making it easier to handle, and furthermore, the release coating can be stably imparted with a heavy release force. On the other hand, when the content is at or below the upper limit of the above range, the release force is stable, and a heavy release force can be achieved with a small amount of release control agent.

[0027] The release control agent may contain (C) an α-olefin having 12 to 24 carbon atoms in addition to the dispersant for component (A) or together with component (A) to impart heavy release to the release coating. Examples of such α-olefins include 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, and 1-eicosene, and preferably an α-olefin having 14 to 18 carbon atoms.

[0028] Inclusion of component (C) in this release control agent is optional, but if component (B) is not included, component (C) is essential. To promote heavy release, component (C) is preferably included. While there are no limitations on the amount of component (C), to promote hardening of the release coating and heavy release, it is preferable that the amount be at most 200 parts by weight, at most 180 parts by weight, at most 150 parts by weight, or at most 100 parts by weight per 100 parts by weight of component (A).

[0029] In addition, the release control agent further contains (D) an average unit formula: (R 2 3SiO 1 / 2 ) b (SiO 4 / 2 ) 1.0 The silicone resin may contain a silicone resin represented by the following formula:

[0030] In the formula, each R 2 are independently an alkyl group having 1 to 6 carbon atoms or an alkenyl group having 2 to 6 carbon atoms, provided that at least one R 2 is the alkenyl group. 2 The alkyl group of R 1 Examples of the alkyl group include the same groups as those shown in the formula (1), and a methyl group is preferred. 2 Examples of the alkenyl group include a vinyl group, an allyl group, a butenyl group, a pentenyl group, and a hexenyl group, and preferably a vinyl group or a hexenyl group.

[0031] In addition, in the formula, b is a group represented by the formula: SiO 4 / 2 For siloxane units represented by the formula: R 2 3SiO 1 / 2is a number in the range of 0.5 to 1.5, and preferably a number in the range of 0.6 to 1.2, or a number in the range of 0.6 to 1.0, indicating the molar ratio of siloxane units represented by the formula: When b is equal to or greater than the lower limit of the above range, the dispersibility of the release control agent is improved, whereas when b is equal to or less than the upper limit of the above range, the mechanical strength of the resulting release coating is improved.

[0032] In the present release control agent, the content of component (D) is not limited, but in order not to affect the releasability of the release coating, it is preferable that the content be at most 300 parts by mass per 100 parts by mass of component (A), because if the content of component (D) is too high, it becomes difficult to achieve heavy release of the release coating.

[0033] Furthermore, the release control agent may contain an organic solvent used when preparing component (A) or when blending component (A) with component (B), as long as it does not impair the object of the present invention. Examples of such organic solvents include aliphatic solvents such as hexane, heptane, and octane; aromatic solvents such as toluene and xylene; and ketone solvents such as acetone. The content of this organic solvent is not limited, and if it is contained, it is preferably at most 100 parts by mass per 100 parts by mass of component (A).

[0034] By incorporating this release control agent into a silicone composition for forming a release coating, the release strength of the resulting release coating from the pressure-sensitive adhesive can be controlled, resulting in a strong release. The curing mechanism of this silicone composition for forming a release coating is not limited, and examples include a hydrosilylation reaction, a condensation reaction, a radical reaction, a radical reaction induced by high-energy radiation, a condensation reaction induced by high-energy radiation, or a hydrosilylation reaction induced by high-energy radiation, with the hydrosilylation reaction being preferred.

[0035] <Silicone composition for forming a peelable coating> The release coating-forming silicone composition of the present invention comprises: (I) the above-mentioned peeling control agent, (II) a diorganopolysiloxane having at least two silicon-bonded alkenyl groups per molecule; (III) an organopolysiloxane having at least two silicon-bonded hydrogen atoms in each molecule, and (IV) Hydrosilylation reaction catalyst The present invention is characterized in that it comprises:

[0036] Component (I) is a release control agent for adjusting the release strength of the release coating obtained by applying the composition to the surface of various substrates such as paper and synthetic resin film and curing it, as described above.

[0037] Component (II) is an optional component that is added when it is difficult to cure the composition using only the alkenyl-containing diorganopolysiloxane or alkenyl-containing silicone resin in component (I) or to adjust the release force. It is a diorganopolysiloxane containing at least two silicon-bonded alkenyl groups per molecule. Examples of alkenyl groups in component (II) include the same alkenyl groups as in component (B), with vinyl and hexenyl being preferred. Examples of groups bonded to silicon atoms other than alkenyl groups in component (II) include the same alkyl groups, aryl groups, and halogen-substituted alkyl groups as in component (B), with methyl being preferred. Furthermore, small amounts of hydroxyl groups or alkoxy groups having 1 to 3 carbon atoms, such as methoxy and ethoxy groups, may be bonded to silicon atoms in component (II), provided that the objectives of the present invention are not impaired.

[0038] The molecular structure of component (II) is not limited, and examples include linear and partially branched linear structures. The viscosity of component (II) at 25°C is also not limited; components ranging from low viscosity to high viscosity gum-like structures can be used. However, the viscosity is preferably in the range of 10 to 10,000 mPa·s or 10 to 1,000 mPa·s, as this provides good coatability for the composition and excellent releasability for the resulting cured coating. The viscosity of component (II) at 25°C can be measured using a rotational viscometer in accordance with JIS K7117-1.

[0039] Examples of such component (II) include the same diorganopolysiloxanes as those listed above for component (B).

[0040] The content of component (II) in this composition is optional, and if there is sufficient alkenyl group-containing diorganopolysiloxane or alkenyl group-containing silicone resin in component (I) to cure the composition, there is no need to include component (II), but if this is not the case, or to adjust the release force or to impart flexibility to the resulting release coating, the content of component (II) is at most 400 parts by weight, preferably at most 100 parts by weight, or at most 50 parts by weight, per 100 parts by weight of components (A) to (C) combined in component (I). This is because, as long as the content of component (II) is not more than the above-mentioned upper limit, the resulting release coating can be sufficiently cured and have a high release strength.

[0041] Component (III) is the crosslinking agent for this composition and is an organopolysiloxane containing at least two silicon-bonded hydrogen atoms per molecule. Examples of groups other than hydrogen atoms bonded to silicon atoms in component (III) include alkyl groups having 1 to 6 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, and hexyl; aryl groups having 6 to 12 carbon atoms, such as phenyl, tolyl, and xylyl; and halogen-substituted alkyl groups having 1 to 6 carbon atoms, such as 3,3,3-trifluoropropyl. Methyl groups are preferred. Furthermore, silicon atoms in component (III) may be bonded to small amounts of hydroxyl groups or alkoxy groups having 1 to 3 carbon atoms, such as methoxy and ethoxy, as long as the objective of the present invention is not impaired.

[0042] The molecular structure of component (III) is not limited, and may be linear, partially branched linear, branched, resinous, or cyclic. It is preferably linear, partially branched linear, or resinous. The viscosity of component (III) at 25°C is also not limited, but is preferably in the range of 1 to 1,000 mPa·s or 5 to 200 mPa·s. The viscosity of component (III) at 25°C can be measured using a rotational viscometer conforming to JIS K7117-1.

[0043] Examples of such component (III) include methylhydrogenpolysiloxanes terminated at both molecular chain ends with trimethylsiloxy groups, methylhydrogensiloxane-dimethylsiloxane copolymers terminated at both molecular chain ends with trimethylsiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymers terminated at both molecular chain ends with dimethylhydrogensiloxy groups, and dimethylpolysiloxanes terminated at both molecular chain ends with dimethylhydrogensiloxy groups, and compounds of the formula: H(CH3)2SiO 1 / 2 Siloxane units represented by the formula: SiO 4 / 2 and copolymers comprising siloxane units represented by the formula: (CH3)3SiO 1 / 2 Siloxane units represented by the formula: H(CH3)2SiO 1 / 2 Siloxane units represented by the formula: SiO 4 / 2Examples include copolymers comprising siloxane units represented by the following formula:

[0044] The content of component (III) in this composition is not limited, but is an amount such that the number of silicon-bonded hydrogen atoms in this component is in the range of 0.5 to 10 moles per mole of total alkenyl groups in the composition, preferably in the range of 1.0 to 5.0 moles, or in the range of 1.5 to 4.0 moles. This is because, if the content of component (III) is at or above the lower limit of the above range, the resulting release coating can be sufficiently cured, while, on the other hand, if it is below the upper limit of the above range, the release force of the resulting release coating is less likely to change.

[0045] Component (IV) is a hydrosilylation catalyst that accelerates the curing of the composition, and examples thereof include platinum-based catalysts, rhodium-based catalysts, and palladium-based catalysts. Component (IV) is preferably a platinum-based catalyst, as it significantly accelerates the curing of the composition. Examples of platinum-based catalysts include platinum fine powder, chloroplatinic acid, an alcohol solution of chloroplatinic acid, a platinum-alkenylsiloxane complex, a platinum-olefin complex, and a platinum-carbonyl complex. Platinum-alkenylsiloxane complexes are particularly preferred. In this platinum-alkenylsiloxane complex, examples of the alkenylsiloxane include 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, alkenylsiloxanes in which some of the methyl groups of these alkenylsiloxanes have been substituted with ethyl groups, phenyl groups, etc., and alkenylsiloxanes in which the vinyl groups of these alkenylsiloxanes have been substituted with allyl groups, hexenyl groups, etc. In particular, 1,3-divinyl-1,1,3,3-tetramethyldisiloxane is preferred because the stability of this platinum-alkenylsiloxane complex is good.

[0046] There are no particular restrictions on the amount of component (IV) contained in the composition, so long as it is an amount that promotes curing of the composition. However, it is preferable that the amount of catalyst metal atoms in component (IV) be in the range of 0.01 to 1,000 ppm, 0.01 to 500 ppm, or 0.1 to 500 ppm, by mass, relative to the total of components (A) to (D) and components (II) to (VI) in the composition.

[0047] In order to adjust the curability of the composition or to improve the pot life of the composition at room temperature, the composition may contain alkyne alcohols such as 2-methyl-3-butyn-2-ol, 3,5-dimethyl-1-hexyn-3-ol, 2-phenyl-3-butyn-2-ol, and 1-ethynylcyclohexane-1-ol; (1,1-dimethyl-2-propynyloxy)trimethylsilane, bis(1,1-dimethyl-2-propynyloxy)dimethylsilane, bis(1,1-dimethyl-2-propynyloxy)methylvinylsilane, tris(1,1-dimethyl-2-propynyloxy)methylsilane, tris(1-methyl-1-phenyl ... It is preferable to incorporate a small amount of a (V) hydrosilylation reaction inhibitor, such as a silylated alkyne alcohol such as tetrakis(1,1-dimethyl-2-propynyloxy)silane, tetrakis(1,1-dimethyl-2-propynyloxy)silane, or (1-ethynyl-cyclohexyloxy)dimethylvinylsilane; an eneyne compound such as 3-methyl-3-penten-1-yne or 3,5-dimethyl-3-hexen-1-yne; a cycloalkenylsiloxane 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 triazole compound such as benzotriazole. The amount of such component (V) is not limited, but is preferably within the range of 0.001 to 5% by mass of the composition.

[0048] The present composition may further contain, within the scope of the present invention, a copolymer having (VI) an average unit formula: (R 2 3SiO 1 / 2 ) b (SiO4 / 2 ) 1.0 The silicone resin may contain a silicone resin represented by the following formula:

[0049] In the formula, each R 2 are independently an alkyl group having 1 to 6 carbon atoms or an alkenyl group having 2 to 6 carbon atoms, provided that at least one R 2 is the alkenyl group. 2 The alkyl group of R 1 Examples of the alkyl group include the same groups as those shown in the formula (1), and a methyl group is preferred. 2 Examples of the alkenyl group include a vinyl group, an allyl group, a butenyl group, a pentenyl group, and a hexenyl group, and preferably a vinyl group or a hexenyl group.

[0050] In addition, in the formula, b is a group represented by the formula: SiO 4 / 2 For siloxane units represented by the formula: R 2 3SiO 1 / 2 is a number in the range of 0.5 to 1.5, and preferably a number in the range of 0.6 to 1.2, or a number in the range of 0.6 to 1.0, representing the molar ratio of siloxane units represented by the formula: When b is equal to or greater than the lower limit of the above range, the coatability of the composition is improved, whereas when b is equal to or less than the upper limit of the above range, the mechanical strength of the resulting release coating is improved.

[0051] While there are no particular limitations on the amount of component (VI) in the present composition, it is preferable that the amount be at most 80 parts by mass per 100 parts by mass of the total of components (A), (B), and (C) in component (I). This is because, when the amount of component (VI) is below the upper limit of the above range, the releasability of the resulting release coating is not affected.

[0052] Furthermore, the present composition may contain an organic solvent to improve the coating workability of the present composition and to adjust the coating amount on the substrate surface, as long as the object of the present invention is not impaired. Examples of such organic solvents include aliphatic solvents such as hexane, heptane, and octane; aromatic solvents such as toluene and xylene; and ketone solvents such as acetone. The content of this organic solvent is not limited and can be appropriately adjusted depending on the coating amount, etc.

[0053] <Release liner> The release liner of the present invention is characterized by having a release coating 2 formed on the surface of a film- or tape-like substrate 1, using the above-described silicone composition for forming a release coating, as shown in Figure 1. Examples of substrate 1 include papers such as Japanese paper, paperboard, corrugated cardboard, glassine paper, clay-coated paper, polyolefin-laminated paper, polyethylene-laminated paper, and synthetic paper; plastic films such as polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polycarbonate, polyethylene terephthalate, and nylon; fabrics such as natural fiber fabrics, synthetic fiber fabrics, and artificial leather fabrics; and other materials such as glass wool and metal foil.

[0054] The release liner of the present invention can be produced by applying the silicone composition for forming a release coating to the surface of a substrate using, for example, gravure coating, bar coating, spray coating, spin coating, knife coating, roll coating, or die coating, and then curing the composition at room temperature or by heating to form a release coating. Furthermore, in the release liner of the present invention, the coating weight of the release coating formed on the surface of the substrate (after drying and curing) is not limited, but is preferably 0.01 to 10 g / m. 2 or 0.1 to 5 g / m 2 is within the range.

[0055] The release liner of the present invention may further comprise a pressure-sensitive adhesive 3 formed on a release coating 2 formed on the surface of a substrate 1, as shown in Figure 2. Examples of such pressure-sensitive adhesive 3 include silicone-based pressure-sensitive adhesives and acrylic-based pressure-sensitive adhesives. [Example]

[0056] The release control agent, release coating-forming silicone composition, and release liner of the present invention are described in more detail below with reference to the following examples. The release liner was prepared, and the release force and residual adhesive rate of the adhesive were measured as follows.

[0057] <How to make a release liner> To adjust the viscosity, the silicone composition for forming a release coating was diluted with heptane so that the total of components (A) to (D) and components (II) to (VI) in the composition was 10% by mass. This solution was applied to the surface of polyethylene-laminated kraft paper using a Mayer bar #5, and after drying and curing, 0.6 to 0.8 g / m 2 The resulting mixture was cured by heating in a hot air dryer at 120°C for 30 seconds to prepare a release liner.

[0058] <Peel force measurement> The release liner prepared by the above method was treated in a dryer at 70°C for 3 days, after which a 25 mm wide adhesive tape (Tesa 7475 tape; a trade name of Tesa Tape, Inc.) was attached, and the release liner was cut into 30 mm wide strips with the adhesive tape in the center to prepare a test specimen. A part of this test specimen was dried at 23°C with 20 g / cm 2 The test piece was then treated for one day with a load of 20 g / cm applied, and then the load was removed and the test piece was left for 30 minutes. After that, the Tesa 7475 tape was pulled at an angle of 180° and at a peeling speed of 0.3 m / min using a tensile tester, and the peel strength (gf / 25 mm) was measured. The remaining test piece was then dried in a dryer at 70°C with a tensile strength of 20 g / cm. 2 The load was applied and the specimen was treated for 1 day, then the load was removed and the specimen was air-cooled for 30 minutes, and the peel strength was measured in the same manner as above.

[0059] <Residual adhesion rate> The release liner prepared by the above method was treated in a dryer at 70°C for 3 days, after which a 38mm wide adhesive tape (Polyester Adhesive Tape 31B; product name manufactured by Nitto Denko Corporation) was attached, and the release liner was cut into 45mm wide strips around the adhesive tape to prepare a test specimen. For reference, a similar test specimen was also prepared using this adhesive tape and a Teflon (registered trademark) sheet as the release liner. These test specimens were dried in a dryer at 70°C under a pressure of 27g / cm. 2 After applying a load of 0.05g for one day, the tape was air-cooled for about 30 minutes. The adhesive tape was then attached to a 200 μm thick polyethylene terephthalate film and pressed back and forth twice with a 2 kg tape roller. The adhesive tape was then pulled at an angle of 180° at a peeling speed of 0.3 m / min using a tensile tester, and the peel strength (gf / 38 mm) was measured. The residual adhesion rate was defined as the percentage of the adhesive strength when the release liner prepared in the example was used relative to the adhesive strength when a Teflon (registered trademark) sheet was used as the release liner.

[0060] <Examples 1-19 and Comparative Examples 1-6> Release control agents and silicone compositions for forming release coatings containing them were prepared by uniformly mixing the components listed below to obtain the compositions shown in Tables 1 to 5. The content of the hydrosilylation catalyst in the silicone composition for forming release coatings was adjusted to provide 100 ppm of platinum metal, by mass, relative to the total of components (A) to (D) and components (II) to (VI) in the composition.

[0061] The following components were used as the silicone resin (A). (a-1): Weight average molecular weight of 4490 in terms of standard polystyrene measured by gel permeation chromatography, average unit formula: [(CH3)3SiO 1 / 2 ] 0.75 (SiO 4 / 2 ) 1.0 Silicone resin (content of silicon-bonded hydroxyl groups = 3.0 mass%) (a-2): Weight average molecular weight of 4900 in terms of standard polystyrene measured by gel permeation chromatography, average unit formula: [(CH3)3SiO 1 / 2 ] 0.74 (SiO 4 / 2 ) 1.0 Silicone resin (content of silicon-bonded hydroxyl groups = 3.0 mass%) (a-3): Weight average molecular weight of 2240 in terms of standard polystyrene measured by gel permeation chromatography, average unit formula: [(CH3)3SiO 1 / 2 ] 0.97 (SiO 4 / 2 ) 1.0 Silicone resin (content of silicon-bonded hydroxyl groups = 2.8% by mass) (a-4): Weight average molecular weight of 6860 in terms of standard polystyrene measured by gel permeation chromatography, average unit formula: [(CH3)3SiO 1 / 2 ] 0.92 (SiO 4 / 2 ) 1.0 Silicone resin (content of silicon-bonded hydroxyl groups = 1.0 mass%)

[0062] The following components were used as the diorganopolysiloxane of component (B). (b-1): Dimethylpolysiloxane with a viscosity of 60 mPa·s and terminated at both ends with dimethylvinylsiloxy groups (vinyl group content = 1.5% by mass) (b-2): Dimethylsiloxane-methylhexenylsiloxane copolymer with a viscosity of 200 mPa·s, both ends of which are capped with dimethylvinylsiloxy groups (vinyl group content = 1.1% by mass).

[0063] The following components were used as the α-olefins of component (C). (c-1): 1-hexadecene (c-2): 1-tetradecene (c-3): 1-octadecene

[0064] The following components were used as component (D): (d-1): Average unit formula: [(CH2=CH)(CH3)2SiO 1 / 2 ] 0.05 [(CH3)3SiO 1 / 2 ] 0.43 (SiO 4 / 2 ) 0.52 Silicone resin (vinyl group content = 2.0 mass%)

[0065] (E) As the organic solvent, the following components were used: (e-1): Xylene

[0066] The following components were used as component (II): (ii-1): Dimethylpolysiloxane with a viscosity of 60 mPa·s and terminated at both ends with dimethylvinylsiloxy groups (vinyl group content = 1.5% by mass) (ii-2): Dimethylsiloxane-methylhexenylsiloxane copolymer (vinyl group content = 1.1% by mass) capped at both ends of the molecular chain with dimethylvinylsiloxy groups, with a viscosity of 200 mPa·s

[0067] The following components were used as component (III): (iii-1): Methylhydrogenpolysiloxane with a viscosity of 20 mPa·s and terminated at both ends with trimethylsiloxy groups (content of silicon-bonded hydrogen atoms = 1.6% by mass) (iii-2): Methylhydrogensiloxane-dimethylsiloxane copolymer with both ends capped with trimethylsiloxy groups, viscosity 70 mPa·s (content of silicon-bonded hydrogen atoms = 1.0 mass%)

[0068] The following components were used as component (IV): (iv-1): A 1,3-divinyltetramethyldisiloxane solution of a platinum 1,3-divinyltetramethyldisiloxane complex having a platinum concentration of 0.6% by mass.

[0069] The following components were used as component (V): (v-1): 1-ethynyl-cyclohexan-1-ol (v-2): 2-methyl-3-butyn-2-ol

[0070] The following components were used as component (VI): (vi-1):Average unit formula: [(CH2=CH)(CH3)2SiO 1 / 2 ] 0.05 [(CH3)3SiO 1 / 2 ] 0.43 (SiO 4 / 2 ) 0.52 Silicone resin (vinyl group content = 2.0 mass%)

[0071] (VII) As the organic solvent, the following components were used: (vii-1): Heptane

[0072] [Table 1]

[0073] [Table 2]

[0074] [Table 3]

[0075] [Table 4]

[0076] [Table 5] [Industrial Applicability]

[0077] The silicone composition for forming release coatings containing the release control agent of the present invention exhibits a relatively high release force against pressure-sensitive adhesives, yet changes little in release force after long-term aging in a state where the pressure-sensitive adhesive is still in close contact with the composition, and it is capable of forming a release coating that does not reduce the residual adhesive strength of the pressure-sensitive adhesive. Therefore, the composition is suitable for applications requiring long-term control of release performance, such as adhesive labels, adhesive stickers, adhesive tapes, casting paper, and optical adhesive films. [Explanation of symbols]

[0078] 1 Base material 2 Peelable coating 3. Adhesive

Claims

1. (A) Average unit formula: (R １ ３ SiO １／２ ) ａ (SiO ４／２ ) １.０ (In the formula, each R １ are independently alkyl groups having 1 to 6 carbon atoms, and a is a number between 0.5 and 1.

5. and the silicone resin has a weight average molecular weight of 3,000 to 6,000 in terms of standard polystyrene as determined by gel permeation chromatography, A release control agent comprising at least one of (B) a diorganopolysiloxane having at least two silicon-bonded alkenyl groups in one molecule and (C) an α-olefin having 12 to 24 carbon atoms, The content of the (B) component is 0 to 150 parts by mass per 100 parts by mass of the (A) component, The content of the component (C) is 0 to 200 parts by mass per 100 parts by mass of the component (A).

2. 2. The release control agent according to claim 1, wherein component (A) is a silicone resin containing 2 to 5% by mass of hydroxyl groups bonded to silicon atoms.

3. 3. The release control agent according to claim 1, wherein component (C) is an α-olefin having 14 to 18 carbon atoms.

4. Furthermore, at most 300 parts by mass of (D) an average unit formula: (R ２ ３ SiO １／２ ) ｂ (SiO ４／２ ) １.０ (In the formula, each R ２ are independently an alkyl group having 1 to 6 carbon atoms or an alkenyl group having 2 to 6 carbon atoms, provided that at least one R ２ is the alkenyl group, and b is a number from 0.5 to 1.

5. The release control agent according to claim 1 , comprising a silicone resin represented by the formula:

5. (I) the peeling control agent according to any one of claims 1 to 4, (II) a diorganopolysiloxane having at least two silicon-bonded alkenyl groups per molecule, in an amount of at most 400 parts by weight per 100 parts by weight of components (A), (B), and (C) combined; (III) an organopolysiloxane having at least two silicon-bonded hydrogen atoms per molecule, in an amount such that there are 0.5 to 10 moles of silicon-bonded hydrogen atoms in this component per mole of total alkenyl groups in the composition; and (IV) Hydrosilylation reaction catalyst A silicone composition for forming a release coating comprising:

6. 6. The release coating-forming silicone composition according to claim 5, further comprising (V) a hydrosilylation reaction inhibitor in an amount of 0.001 to 5% by mass of the composition.

7. Furthermore, (VI) the average unit formula: (R ２ ３ SiO １／２ ) ｂ (SiO ４／２ ) １.０ (In the formula, each R ２ are independently an alkyl group having 1 to 6 carbon atoms or an alkenyl group having 2 to 6 carbon atoms, provided that at least one R ２ is the alkenyl group, and b is a number from 0.5 to 1.

5.

7. The silicone composition for forming a release coating according to claim 5, wherein component (I) contains at most 50 parts by weight of a silicone resin represented by the formula:

8. A release liner comprising a film- or tape-like substrate on the surface of which a release coating is formed from the silicone composition for forming release coatings according to any one of claims 5 to 7.

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