TW201842071A - Heavy-release composition for release sheets, and release sheet - Google Patents

Abstract

A heavy-release composition for release sheets, comprising (A) a one-end-reactive organopolysiloxane having one alkenyl group at one end, (B) an organopolysiloxane having at least two alkenyl groups per molecule, (C) an organohydrogenpolysiloxane having at least two hydrogen atoms each bonded to a silicon atom per molecule, and (D) a platinum-group metal catalyst, wherein the amount of the component (A), the structure of the component (B) and the structure of the component (C) are adjusted to respective specified ranges.

Description

Heavy release composition for release sheet and release sheet

The present invention relates to a heavy-peeling composition for an addition reaction-hardening type peeling sheet that provides an excellent heavy-peeling effect, and a peeling sheet using the same.

Conventionally, in order to prevent adhesion and fixation of a base material such as paper or plastic and an adhesive material, a hardened film of an organic polysiloxane composition is formed on the base material surface to impart peeling properties. As a method for forming an organic polysiloxane curing film on the substrate surface, the method of forming a peelable film by an addition reaction is excellent in hardenability, and can correspond to various peeling characteristics from low-speed peeling to high-speed peeling. It is widely used.

The method for forming a peelable film by an addition reaction is a type in which an organic polysiloxane composition is dissolved in an organic solvent, an emulsifier is dispersed in water and used as an emulsion, and only organic polysiloxane is used. The solvent-free type composed of alkane has the disadvantage that it may be harmful to the human body or the environment. Therefore, in terms of safety, the solvent-based type is being switched to the solvent-free type.

In general, the organopolysiloxane composition for release paper is required to have various peeling forces according to the purpose, and it is necessary for heavy peeling, and it is widely used to add an alkenyl-containing MQ resin (M unit A composition which means R ' ₃ SiO _1/2 unit and Q unit means SiO _4/2 unit. R' represents a monovalent hydrocarbon group. The same applies hereinafter.

However, the MQ resin containing an alkenyl group is often a resinous or highly viscous compound. When it is added in a large amount, it must be diluted with an organic solvent before use. In addition, if it is added in a small amount, it can be used without a solvent, but the re-peeling effect is insufficient in this case. In addition, it is known that the MQ resin containing an alkenyl group tends to decrease in peeling force with time as compared with the peeling force immediately after hardening, and it is required that the peeling force with time does not change.

On the other hand, when the tape is peeled from the heavily peeled sheet, peeling sound (tearing sound, zipping) may be a problem. Although there are many unknown parts of the detailed mechanism of the tearing sound, especially for a sheet that is peeled off with a high crosslink density, the tearing sound tends to occur easily. Therefore, when developing a heavily peeled sheet, suppression of tearing sound is also an important issue.

Japanese Unexamined Patent Publication No. 5-53183 (Patent Document 1) refers to an organic polysiloxane composition for release paper which uses an alkenyl-containing MQ resin and an alkenyl-free MQ resin in combination, and the peeling force with time Although the amount of change can be reduced, the effect of heavy peeling is insufficient.

Japanese Patent No. 2750896 (Patent Document 2) is obtained by blending a resin containing an alkenyl group in an organic polysiloxane composition for a solvent-type addition reaction type release paper, and has low-temperature hardening properties and little change over time. Peeling force, but not for the purpose of heavy peeling, peeling force is not large. In addition, as a method of adding an adhesive polyorganosiloxane resin to the addition reaction type organic polysiloxane composition to perform re-peeling, the following technique is reported.

Japanese Unexamined Patent Publication No. 6-086582 (Patent Document 3) is an adhesive organic polysiloxane protection coating agent, which has a hardenable silicone rubber, an organic polysiloxane containing hydroxyl groups at both ends, and an MQ containing The unit of silicone is partially dehydrated and condensed. Since the silicone rubber and the silicone resin are high in viscosity or solid, a solvent is necessary.

Japanese Patent Application Laid-Open No. 10-110156 (Patent Document 4) relates to a technology of an organopolysiloxane-based pressure-sensitive adhesive based on a mixture or a partial condensation product of vinyl raw rubber and MQ resin. Since it uses a silicone rubber, a solvent is necessary, and the effect as a heavy release composition for release paper is not mentioned.

Japanese Patent Application Laid-Open No. 2010-37557 (Patent Document 5) is a peeling adjusting agent, which makes the molar ratio of (a1) M unit to Q unit 0.6 to 1.0, and the content of hydroxyl or alkoxy group is 100 parts by mass of MQ-type resin in the range of 0.3 to 2.0% by mass, and (a2) 20 to 150 parts by mass of chain polydiorganosiloxane having an average degree of polymerization of 100 to 1,000 of hydroxyl or alkoxy groups, and a condensation reaction is performed The obtained organic polysiloxane resin-organic polysiloxane condensation reaction product. In Patent Document 6, the peeling force in the examples is only 1.4 times to 2.2 times lower at a low speed (0.3 m / min) than the comparative example in which the condensation reactant is not added, and sufficient heavy peeling is not obtained. effect. This is speculated that the content of hydroxyl or alkoxy groups used in (a1) is in the range of 0.3 to 2.0% by mass, which is low, the reaction point with (a2) is small, and the crosslinked structure obtained by sufficient condensation is not available. Therefore.

Japanese Patent Application Laid-Open No. 5-329184 (Patent Document 6) is a patent for the purpose of suppressing the tearing sound when the tape is peeled off from a paper diaper. The silicone resin release agent is mixed with a release layer of MQ resin. It is composed of an adhesive layer mixed with an AB block copolymer and a tackifier. According to this patent, although a cracking sound can be suppressed, a solvent is used for the peeling layer, and only evaluation as an adhesive is performed, and peeling characteristics are not mentioned.

Japanese Patent Application Laid-Open No. 6-228501 (Patent Document 7) proposes a method of increasing the peeling force of a pressure-sensitive adhesive without using an MQ resin containing an alkenyl group. This is because the composition that uses a higher alkenyl group to adjust the crosslinking density at the cross-linking site, but does not mention the tearing sound, and does not use an MQ resin containing an alkenyl group, so the heavy peeling effect is also insufficient.

Japanese Patent Application Laid-Open No. 7-188562 (Patent Document 8) is a heavy peeling composition using an alkenyl-containing MQ resin, an α, ω-diene, and an organohydrogenpolysiloxane. By using an MQ resin containing an alkenyl group and an α, ω-diene, it has a very high peeling force, but there is no mention of the problem of tearing sound, nor does it suggest a solution to this problem. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 5-53183 [Patent Literature 2] Japanese Patent Publication No. 2750896 [Patent Literature 3] Japanese Patent Publication No. 6-086582 [Patent Literature 4] Japanese Patent Publication No. 10-110156 [Patent Document 5] JP 2010-37557 [Patent Document 6] JP 5-329184 [Patent Document 7] JP 6-228501 [Patent Document 8] JP 7-185862 Bulletin

[Problems to be Solved by the Invention]

The present invention has been made in view of the above-mentioned facts, and its object is to provide a heavy-peeling composition for a peeling sheet, which is excellent in heavy-peeling effect, suppresses the tearing sound at the time of peeling, and further reduces the degradation of the peeling force over time after curing, and forms the same. Release sheet with its hardened film. [Means to solve the problem]

As a result of diligent investigations by the present inventors in order to achieve the above-mentioned object, it was found that since a single-terminal reactive organopolysiloxane having one alkenyl group at the (A) terminal has at least two in one molecule (B) Composition composed of alkenyl organic polysiloxane, (C) organic hydrogen polysiloxane having at least two hydrogen atoms bonded to silicon atom in one molecule, and (D) platinum group metal catalyst In the component (A), the amount of the component (A) with respect to the total amount of the component (A) and the component (B) is set to a specific range, and the component (B) has an organic polysiloxane resin (B-1) having a three-dimensional network structure. ) An organic hydrogen polysiloxane having a specific mass ratio with a linear or branched organic polysiloxane (B-2) and having a side chain having a hydrogen atom bonded to a silicon atom in the component (C) The alkane (C-1) has a specific mass ratio with an organohydrogenpolysiloxane (C-2) having a terminal and a side chain not having a hydrogen atom bonded to a silicon atom. The composition obtained has excellent re-peeling effect and suppresses peeling. The present invention has completed the present invention by reducing the tearing sound and the decrease in the peeling force over time after hardening.

Therefore, the present invention provides the following inventions. [1]. A heavy release composition for a release sheet, which contains (A) the following general formula (1): (In the formula, R ¹ represents an alkenyl group, R ² independently represents an unsubstituted or substituted monovalent hydrocarbon group containing no alkenyl group, and a is a positive number satisfying 1 ≦ a ≦ 200.) Single-end reactive organic polysiloxane: 10 to 35 parts by mass (B) of the following average composition formula (2) relative to the total amount of the (A) component and the (B) component: (In the formula, R ³ is an unsubstituted or substituted monovalent hydrocarbon group, and b is a positive number satisfying 0 ≦ b ≦ 3.) An organic polysiloxane having at least two alkenyl groups in one molecule represented by: For the total of 100 parts by mass of the components (A) and (B), the component (B) is 65 to 90 parts by mass (C) and the following average composition formula (3): (In the formula, R ⁴ is independently an unsubstituted or substituted monovalent hydrocarbon group containing no alkenyl group, and c and d are those satisfying 0.7 ≦ c ≦ 2.1, 0.001 ≦ d ≦ 1.0, and 0.8 ≦ c + d ≦ 3.0. (Positive number) An organohydrogenpolysiloxane having at least two hydrogen atoms bonded to a silicon atom in one molecule: (C) For all alkenyl groups in the components (A) and (B) (D) Platinum group metal catalyst: effective amount of heavy peeling composition for peeling sheet, characterized by the above-mentioned (B) component , Is an organic polysiloxane resin (B-1) having at least two alkenyl groups in one molecule and having a three-dimensional network structure at 25 ° C as a wax or solid, and having a liquid end at 25 ° C having Combination of linear or branched organic polysiloxane (B-2) with at least 2 alkenyl groups, the mass ratio of (B-1) component to (B-2) component (B-2) / ( B-1) is 0.1 to 0.5, and the component (C) is an organohydrogenpolysiloxane (C-1) having a hydrogen atom bonded to a silicon atom in a side chain, and having a bond at the end and no side chain The combination of organohydrogen polysiloxane (C-2) with hydrogen atom of silicon atom, The mass ratio (C-2) / (C-1) of the (C-1) component to the (C-2) component is 1 to 5. [2]. The heavy release composition for release sheet according to [1], wherein the component (B-1) is an average composition formula (4) below: (In the formula, R ⁵ independently represents an alkenyl group, and R ⁶ independently represents an unsubstituted or substituted monovalent hydrocarbon group containing no alkenyl group, but at least 80 mole% of all R ⁶ is methyl, e, f , G, h, i, j, and k are numbers that satisfy e ≧ 0, f ≧ 0, g ≧ 0, h ≧ 0, i ≧ 0, j ≧ 0, and k ≧ 0, respectively, but satisfy f + g + i> 0, i + j + k> 0, (e + f + g + h) / (i + j + k) <1.3, and e + f + g + h + i + j + k = 1 (Number) represents an organic polysiloxane resin having at least two alkenyl groups in a molecule and having a three-dimensional network structure at 25 ° C, which is waxy or solid. [3]. The heavy peeling composition for a release sheet according to [1] or [2], wherein the above (B-2) has the following average composition formula (5): (In the formula, R ⁷ independently represents an alkenyl group, and R ⁸ independently represents an unsubstituted or substituted monovalent hydrocarbon group containing no alkenyl group, but at least 80 mole% of all R ⁸ is methyl, l, m , N, p, and q are numbers satisfying l ≧ 0, m> 0, n ≧ 0, p ≧ 0, and q ≧ 0, respectively, but satisfying n + p + q> 0, p + q <0.1 , And l + m + n + p + q = 1) means a linear or branched organic polysiloxane that is liquid at 25 ° C and has at least 2 alkenyl groups at the end. [4]. The heavy release composition for a release sheet according to any one of [1] to [3], wherein the component (C-1) is the following average composition formula (6): (In the formula, R ⁹ independently represents an unsubstituted or substituted monovalent hydrocarbon group containing no alkenyl group, and r, s, t, u, v, w, and x are those satisfying r ≧ 0, s ≧ 0, t ≧ 0, u ≧ 0, v ≧ 0, w ≧ 0, and x ≧ 0, except that it satisfies t + v> 0 and s + t + u + v + w + x + y = 1 An organohydrogenpolysiloxane represented by a side chain having a hydrogen atom bonded to a silicon atom. [5]. The heavy release composition for a release sheet according to any one of [1] to [4], wherein the component (C-2) is an average composition formula (7) below: (In the formula, R ¹⁰ independently represents an unsubstituted or substituted monovalent hydrocarbon group containing no alkenyl group, α, β, γ, δ, and ε, respectively, satisfying α ≧ 0, β> 0, and γ ≧ 0. , Δ ≧ 0 and ε ≧ 0, but satisfying γ + δ + ε> 0, δ + ε <0.1, and α + β + γ + δ + ε = 1) represent that the end has and side An organohydrogenpolysiloxane that does not have a hydrogen atom bonded to a silicon atom. [6]. The heavy release composition for release sheet according to any one of [1] to [5], wherein the viscosity at 25 ° C is 50 to 2,000 mPams. [7] A release sheet having a flaky substrate, and the hardening of the heavy release composition for a release sheet according to any one of [1] to [6] on one or both sides of the surface of the substrate Capsule. [8]. The peeling sheet according to [7], in which a Tesa7475 tape is attached to the cured film, and the peeling force measured at an angle of 180 ° and a peeling speed of 0.3 m / min is 5 to 20 N / 25 mm. [Effect of the invention]

The heavy-peeling composition for the release sheet of the present invention can also obtain a very large peeling force compared with the conventional heavy-peeling composition. In addition, since the tearing sound at the time of peeling is suppressed, and the decrease of the peeling force with time after hardening is also small, it is useful as a material for a peeling sheet for heavy peeling.

Hereinafter, the present invention will be described in detail. [(A) component] (A) component is the following general formula (1): (In the formula, R ¹ is an alkenyl group, and R ² is an unsubstituted or substituted monovalent hydrocarbon group not containing an alkenyl group, and a is a positive number satisfying 1 ≦ a ≦ 200.) Single-end reactive organic polysiloxane. The cross-linking density is adjusted by using a single-terminal reactive organic polysiloxane having one alkenyl group at the end of the component (A). The release sheet for the release sheet of the present invention (hereinafter, referred to as a re-release composition) Or), can provide peeling sheet without tearing sound. Moreover, (A) component can be used individually by 1 type or in combination of 2 or more types as appropriate.

In the general formula (1), R ¹ is independently an alkenyl group, and the number of carbon atoms thereof is usually 2 to 8, preferably 2 to 4. Specific examples include vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl and the like, and vinyl is preferred.

R ² is independently an unsubstituted or substituted monovalent hydrocarbon group that does not contain an alkenyl group, and is not particularly limited as long as it does not have an alkenyl group. For example, the number of unsubstituted or substituted carbon atoms is usually 1 to 12, It is preferably a monovalent hydrocarbon group of 1 to 10. Examples of the unsubstituted or substituted monovalent hydrocarbon group include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, and heptyl; cycloalkyl groups such as cyclohexyl; phenyl, tolyl, Aryl groups such as xylyl, naphthyl, etc .; aralkyl groups such as benzyl, phenethyl, and the like; chloroform in which some or all of the hydrogen atoms of these groups are replaced by halogen atoms such as chlorine, fluorine, and bromine atoms Alkyl, 3-chloropropyl, 3,3,3-trifluoropropyl and the like. Among them, an alkyl group is preferred, and a methyl group is more preferred.

a is a positive number satisfying 1 ≦ a ≦ 200, preferably 5 ≦ a ≦ 100, and more preferably 5 ≦ a ≦ 30. When a exceeds 200, the component (A) functions as a light peeling component, and therefore it is difficult to obtain a target heavy peeling effect. In addition, the viscosity of the composition becomes high, and there is a problem that it cannot be used without dilution with a solvent.

Specific examples of the component (A) include the following compounds (wherein Bu represents butyl).

Content of (A) component is 10-35 mass parts with respect to 100 mass parts of the total of (A) component and (B) component. When the content of the component (A) is less than 10 parts by mass, the cross-linking density of the hardened material increases, and a problem of tearing sound occurs. In addition, when the content of the component (A) exceeds 35 parts by mass, the crosslink density of the cured product needs to be lowered more than necessary, and thus it is difficult to obtain the intended heavy peeling effect.

[(B) component] (B) component is the following average composition formula (2): (In the formula, R ³ is an unsubstituted or substituted monovalent hydrocarbon group, and b is a positive number satisfying 0 ≦ b ≦ 3.) An organopolysiloxane having at least two alkenyl groups in one molecule. (B) A component can be used individually by 1 type or in combination of 2 or more types as appropriate.

In the above average composition formula (2), among the unsubstituted or substituted monovalent hydrocarbon groups represented by R ³ , preferably 0.1 to 40 mole% is an alkenyl group, and more preferably 0.2 to 20 mole%. When the content of the alkenyl group satisfies the range of 0.1 to 40 mol%, the crosslinking reaction proceeds sufficiently, and a film having a high re-peeling effect can be obtained.

Examples of the alkenyl group in the component (B) are the same as those specifically exemplified as R ¹ in the formula (1) as the component (A), and among them, a vinyl group is particularly preferred. The non-substituted or substituted monovalent hydrocarbon group other than the alkenyl group in the component (B) may be the same as those specifically exemplified as R ² in the general formula (1) as the component (A), and among them, an alkyl group is particularly preferred. More preferably, it is methyl.

In the present invention, the component (B) is an organic polysiloxane resin (B-1) having at least two alkenyl groups in one molecule and having a three-dimensional network structure at 25 ° C as a wax or solid, and 25 ° C is a combination of linear or branched organic polysiloxane (B-2) having at least two alkenyl groups at the liquid end, and (B-1) and (B-2) The mass ratio (B-2) / (B-1) is 0.1 to 0.5.

[(B-1) Component] "Wax-like" means a gel-like (raw rubber-like) material that hardly shows self-flowability at 25 ° C and is 10,000 Pa · s or more, particularly 100,000 Pa · s or more. The measurement of the viscosity is a value of the absolute viscosity (the same applies hereinafter) measured at 25 ° C by a B-type rotary viscometer.

(B-1) includes the following average composition formula (4): (In the formula, R ⁵ independently represents an alkenyl group, and R ⁶ independently represents an unsubstituted or substituted monovalent hydrocarbon group containing no alkenyl group, but at least 80 mole% of all R ⁶ is methyl, e, f , G, h, i, j, and k are numbers that satisfy e ≧ 0, f ≧ 0, g ≧ 0, h ≧ 0, i ≧ 0, j ≧ 0, and k ≧ 0, respectively, but satisfy f + g + i> 0, i + j + k> 0, (e + f + g + h) / (i + j + k) <1.3, and e + f + g + h + i + j + k = 1 (Number)), and the molecule contains at least two alkenyl groups bonded to a silicon atom, and trifunctional siloxane units and / or SiO _4/2 units are required components.

The alkenyl group represented by R ⁵ in the average composition formula (4) may be the same as those specifically exemplified as R ¹ in the formula (1) as the component (A), and particularly preferably a vinyl group. The unsubstituted or substituted monovalent hydrocarbon group other than the alkenyl group represented by R ⁶ may be the same as those specifically exemplified as R ² in the formula (1) as the component (A), and at least 80 moles of all R ⁵ % Is methyl. When the ratio of the methyl group is less than 80 mol% of all R ⁵ , the compatibility with the component (A) is poor, so the composition may be turbidly separated, and a uniform film may not be obtained.

e is preferably 0 to 0.65, f is preferably 0 to 0.65, g is preferably 0 to 0.5, h is preferably 0 to 0.5, i is preferably 0 to 0.8, j is preferably 0 to 0.8, and k is more It is preferably a number from 0 to 0.6. In addition, f + g + i is preferably a number from 0.1 to 0.8, i + j + k is preferably a number from 0.1 to 0.8, particularly preferably a number from 0.2 to 0.6, (e + f + g + h) / (i + j + k) is preferably a number from 0.6 to 1.25.

Examples of the organic polysiloxane resin represented by the average composition formula (4) include the following. (In the formula, Me represents a methyl group, Vi represents a vinyl group, and e, f, g, h, i, j, and k are as defined in the above-mentioned average composition formula (4)), etc., and Me ₃ SiO _{1 is} particularly used. Organic polysiloxane resins composed of _{/ 2} , ViMe ₂ SiO _1/2 and SiO _4/2 units are more preferred. By using such an organic polysiloxane resin, the crosslinked density of the obtained hardened | cured material becomes sufficiently high, and the desired heavy peeling effect can be obtained.

[(B-2) Component] A linear or branched organic polysiloxane having a liquid state at 25 ° C and having at least two alkenyl groups at the terminal, and the following average composition formula (5) can be cited: (In the formula, R ⁷ independently represents an alkenyl group, and R ⁸ independently represents an unsubstituted or substituted monovalent hydrocarbon group containing no alkenyl group, but at least 80 mole% of all R ⁸ is methyl, l, m , N, p, and q are numbers that satisfy l ≧ 0, m> 0, n ≧ 0, p ≧ 0, and q ≧ 0, respectively, but satisfy n + p + q> 0, p + q <0.1, And l + m + n + p + q = 1).

Examples of the alkenyl group represented by R ⁷ in the average composition formula (5) include the same as those specifically exemplified as R ¹ in the formula (1) as the component (A), and particularly preferred is a vinyl group. An unsubstituted or substituted monovalent hydrocarbon group other than the alkenyl group represented by R ⁸ is the same as that exemplified by R ² in the formula (1) as the component (A), and at least 80 mol% of all R ⁸ Is methyl. When the proportion of methyl groups is less than 80 mol% of all R ⁸ , the compatibility with the component (A) is poor, so the composition may be turbidly separated, and a uniform film may not be obtained.

l is preferably 0 to 0.65, m is preferably 0.01 to 0.65, n is preferably 0 to 1, p is preferably 0 to 0.1, and q is preferably a number of 0 to 0.1. In addition, n + p + q is preferably 0.5 to 1, particularly preferably 0.7 to 1, and p + q is preferably a number less than 0.1. When p + q exceeds 0.1, the cross-linking density of the hardened material increases, and the problem of tearing sound occurs. Specific examples of the above average composition formula (5) include: Indicated linear polysiloxane, Shown as branched-chain polysiloxane. Among them, a linear organic polysiloxane composed of units of ViMe ₂ SiO _1/2 and Me ₂ SiO is more preferably used. By using such an organic polysiloxane, adjustment of the crosslinking density of the obtained hardened | cured material becomes easier.

The viscosity of the component (B) at 25 ° C is preferably 1,000 mPa ･ s or less, more preferably 0.5 to 1,000 mPa ･ s, and still more preferably 2 to 500 mPa ･ s. When the viscosity exceeds 1,000 mPa ･ s, the viscosity of the composition becomes high, and there is a problem that it cannot be used without dilution with a solvent.

(B) The proportion of the organopolysiloxane resin (B-1) having a three-dimensional network structure and the linear or branched organopolysiloxane (B-2) in the component is also the present invention. One of the important factors of the composition. That is, it is necessary to make the mass ratio ((B-2) / (B-1)) of (B-1) component and (B-2) component into 0.1-0.5, Preferably it is 0.2-0.4. When (B-2) / (B-1) is less than 0.1, the crosslinked density of the hardened material is increased, and a tearing sound occurs. When (B-2) / (B-1) exceeds 0.5, the crosslink density of the cured product must be lowered more than necessary, so that it is difficult to obtain the target heavy peeling effect.

The content of the component (B) is 65 to 90 parts by mass based on 100 parts by mass of the total of the components (A) and (B).

[(C) component] (C) component is the following average composition formula (3): (In the formula, R ⁴ is independently an unsubstituted or substituted monovalent hydrocarbon group containing no alkenyl group, and c and d are those satisfying 0.7 ≦ c ≦ 2.1, 0.001 ≦ d ≦ 1.0, and 0.8 ≦ c + d ≦ 3.0. (Positive number) An organohydrogenpolysiloxane having at least two hydrogen atoms bonded to silicon atoms in one molecule.

The component (C) functions as a cross-linking agent that crosslinks with the alkenyl group contained in the components (A) and (B) by a hydrosilylation reaction. From such a viewpoint, the viscosity of the component (C) at 25 ° C is preferably 1,000 mPa ･ s or less, more preferably 0.5 to 1,000 mPa ･ s, and still more preferably 2 to 200 mPa ･ s. In terms of the balance of cross-linking, it is controlled so that the hydrogen atom bonded to the silicon atom in the component (C) becomes 0.5 to the total alkenyl groups in the component (A) and (B). 5.0 mol times, preferably 0.7 to 3.0 mol times. If it is not satisfied that the amount becomes 0.5 to 5.0 mol times, the balance of crosslinking may become unsuitable.

The content of the hydrogen atom bonded to the silicon atom in the component (C) is preferably in the range of 0.001 to 0.02 mol, and more preferably in the range of 0.002 to 0.017 mol per 1 g of the component (C).

In the above average composition formula (3), the unsubstituted or substituted monovalent hydrocarbon group containing no alkenyl group represented by R ⁴ may be specifically exemplified by R ² in formula (1) as the component (A), but more than Preferably, at least 50 mole% of all R ⁴ , typically 60 to 100 mole% is methyl. When the proportion of the methyl group is less than 50 mol% of all R ⁴ , the compatibility with the component (A) and the component (B) is poor, and there may be a problem of turbidity or phase separation of the composition. c is 0.7 ≦ c ≦ 2.1, d is 0.001 ≦ d ≦ 1.0, and c + d is a positive number that satisfies 0.8 ≦ c + d ≦ 3.0.

In the present invention, the component (C) is an organic hydrogen polysiloxane (C-1) having a hydrogen atom bonded to a silicon atom in a side chain, and a hydrogen atom having a terminal and a side chain not bonded to a silicon atom. A combination of atomic organic hydrogen polysiloxane (C-2). The component (C-1) is a component for imparting mainly adhesiveness to a substrate, and the component (C-2) is a component for adjusting a crosslinking density. (C) A component can be used individually by 1 type or in combination of 2 or more types as appropriate.

(C-1) includes the following average composition formula (6): (In the formula, R ⁹ independently represents an unsubstituted or substituted monovalent hydrocarbon group containing no alkenyl group, and r, s, t, u, v, w, and x are those satisfying r ≧ 0, s ≧ 0, t ≧ 0, u ≧ 0, v ≧ 0, w ≧ 0, and x ≧ 0, except that it satisfies t + v> 0 and s + t + u + v + w + x + y = 1 ).

The non-substituted or substituted monovalent hydrocarbon group other than the alkenyl group represented by R ⁹ may be the same as those specifically exemplified as R ² in the formula (1) as the component (A), preferably an alkyl group, more preferably Is methyl.

r is preferably 0 to 0.65, s is preferably 0 to 0.65, t is preferably 0 to 1, u is preferably 0 to 1, v is preferably 0 to 1, and w is preferably 0 to 0.75. It is preferably a number from 0 to 0.65. In addition, t + v is preferably 0.01 to 1.

Specific examples of the above average composition formula (6) include: The cyclic organic hydrogen polysiloxane, Represented linear organic hydrogen polysiloxane, (In the formula, r, s, t, u, v, w, and x are as defined in the above-mentioned average composition formula (6).) Branched-chain organic hydrogen polysiloxane and the like. In particular, it is more preferable to use a linear organic polysiloxane composed of Me ₃ SiO _1/2 and MeHSiO units, or Me ₃ SiO _1/2 , MeHSiO, and Me ₂ SiO units. By using such an organic polysiloxane, adhesion to a substrate can be imparted.

(C-2) Examples (In the formula, R ¹⁰ independently represents an unsubstituted or substituted monovalent hydrocarbon group containing no alkenyl group, α, β, γ, δ, and ε, respectively, satisfying α ≧ 0, β> 0, and γ ≧ 0. , Δ ≧ 0 and ε ≧ 0, but are compounds represented by γ + δ + ε> 0, δ + ε <0.1, and α + β + γ + δ + ε = 1).

The unsubstituted or substituted monovalent hydrocarbon group other than the alkenyl group represented by R ¹⁰ may be specifically exemplified by R ² in the formula (1) as the component (A), and is preferably an alkyl group, more preferably a methyl group. .

α is preferably 0 to 0.65, β is preferably 0.01 to 0.65, γ is preferably 0 to 1, δ is preferably 0 to 0.1, and ε is preferably a number of 0 to 0.1. In addition, γ + δ + ε is preferably 0.5 to 1, particularly preferably 0.7 to 1, and δ + ε is preferably a number less than 0.1. When δ + ε exceeds 0.1, the crosslinking density of the hardened material may increase.

Specific examples of the above average composition formula (7) include: Represented linear organic hydrogen polysiloxane, The branched-chain organic hydrogen polysiloxane and the like. In the structure of the branched-chain organic hydrogen polysiloxane, at least one of 0 to 60 representing the number of each (CH ₃ ) ₂ SiO unit is 1 to 60, and at least one of 0 to 50 is 1 to 50. good. In particular, it is more preferable to use a linear organic polysiloxane composed of Me ₂ HSiO _1/2 and Me ₂ SiO units. By using such an organic polysiloxane, adjustment of the crosslinking density of the obtained hardened | cured material becomes easy.

In the component (C), an organohydrogenpolysiloxane (C-1) component having a hydrogen atom bonded to a silicon atom as a side chain and a hydrogen atom bonded to a silicon atom at the end and not having a side chain is necessary. The ratio of organic hydrogen polysiloxane (C-2) is also one of the important factors of the composition of the present invention. That is, the mass ratio ((C-2) / (C-1)) of the (C-1) component to the (C-2) component must be 1 to 5. When (C-2) / (C-1) is less than 1, the cross-linking density of the hardened material will increase and a problem of tearing will occur. Moreover, when (C-2) / (C-1) exceeds 5, the crosslinking density of a hardened | cured material will fall more than necessary, and it will become difficult to obtain the target heavy peeling effect.

[(D): Platinum group metal catalyst] (D) The platinum group metal catalyst is a catalyst for promoting the addition reaction between (A) component and (B) component and (C) component, It can be used as long as it promotes the so-called hydrosilylation reaction and is known to those skilled in the art. Such platinum group metal catalysts include, for example, platinum-based, palladium-based, rhodium-based, and ruthenium-based catalysts. Among these, platinum-based catalysts are particularly preferably used. Examples of the platinum-based catalyst include chloroplatinic acid, an alcohol solution or an aldehyde solution of chloroplatinic acid, and complexes of chloroplatinic acid with various olefins or vinylsiloxanes. More specifically, a platinum catalyst modified with chloroplatinic acid by 1,3-divinyltetramethyldisilazane is mentioned.

The blending amount of the component (D) may be a so-called effective amount as a catalyst, but specifically, from the viewpoint of obtaining a good hardened film and being economical, compared with the components (A), (B), and (C) The total mass of the component is in the range of 0.1 to 1,000 ppm, and more preferably 1 to 500 ppm in terms of the mass conversion of the platinum group metal.

[Other components] 组成 In the composition of the present invention, other optional components may be blended in addition to the components (A) to (D) described above. Specific examples thereof include the following. These other components can be used individually by 1 type or in combination of 2 or more types as appropriate.

･ Alkenyl group-containing compounds other than (A) and (B) components In the composition of the present invention, in addition to (A) and (B) components, an olefin-containing compound which is subjected to an addition reaction with the (C) component may be blended. Of the compound. Such an alkenyl group-containing compound other than the (A) and (B) components is preferably related to the formation of a cured product. Examples of the compounds other than the (A) and (B) components having at least one alkenyl group per molecule are listed. Of organic polysiloxane. The molecular structure may be, for example, linear, cyclic, branched, or three-dimensional network.

(Component (E)) ･ Addition reaction control agent In order to ensure pot life, an addition reaction control agent may be blended in the composition of the present invention. The addition reaction control agent is not particularly limited as long as it is a compound that has a hardening-suppressing effect on the hydrosilylation catalyst of the component (D), and it can be used as known from the past. Specific examples thereof include phosphorus-containing compounds such as triphenylphosphine; nitrogen-containing compounds such as tributylamine, tetramethylethylenediamine, benzotriazole; sulfur-containing compounds; 1-ethynylcyclohexanol, 3 -Methyl-1-butyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, 3-methyl-1-penten-3-ol, phenylbutynol, etc. Alkynyl alcohols; 3-methyl-3-1-pentene-1-yne, 3,5-dimethyl-1-hexyne-3-yne and other acetylene compounds; containing more than two olefins Compounds; hydroperoxy compounds; maleic acid derivatives and the like.

The degree of the hardening inhibitory effect caused by the addition reaction control agent varies depending on the chemical structure of the addition reaction control agent. Therefore, it is preferable to adjust the addition amount of each addition reaction control agent to an optimum amount. By adding an optimum amount of an addition reaction control agent, the composition becomes excellent in long-term storage stability and heat hardening property at room temperature.

Further, as long as the effect of the present invention is not hindered, other known antioxidants, pigments, stabilizers, antistatic agents, defoamers, adhesion improvers, tackifiers, An inorganic filler such as silicon dioxide.

[Heavy peeling composition for release sheet] The viscosity of the heavy peeling composition of the present invention at 25 ° C is preferably 50 to 2,000 mPa ･ s, and particularly preferably 50 to 1,000 mPa ･ s. When the viscosity falls outside this range, problems such as failure to coat when a hardened film is formed on a substrate, and a uniform film may occur.

Since the heavy peeling composition of the present invention does not require a solvent, it can be used as a solvent-free heavy peeling composition.

[Manufacturing method of heavy peeling composition for release sheet] 重 In the heavy peeling composition of the present invention, in terms of usable time, it is more desirable to mix the above-mentioned (A) to (C) components and arbitrary components in advance, and then Add the (D) component before use.

[Coated Article (Release Sheet)] The release sheet of the present invention is a release sheet having a sheet-like substrate and a hardened film of the above-mentioned heavy release composition on one or both sides of the substrate surface. The hardened film can be formed by coating the heavy peeling composition on one or both sides of the surface of the substrate and heating it.

For example, the heavy peel composition can be directly used as a notch wheel coater, lip coater, roll coater, die coater, knife coater, blade coater, and bar coater. , Kiss coater, gravure coater, wire rod coater, etc .; screen coating, dip coating, cast coating and other coating methods, such as paper, film, etc. One or both sides of the sheet-like substrate are coated with 0.01 to 100 g / m ² , and then heated at 50 to 200 ° C. for 1 to 120 seconds to form a hardened film on the substrate. When producing a release layer on both sides of a base material, it is preferable to perform the operation of hardening a film formation on one side of a base material one by one.

In addition, in the present invention, the release sheet includes, in addition to a sheet-like substrate, paper, and includes those formed of various known films and the like. Examples of the base material include various laminated papers such as polyethylene laminated paper, cellophane, high quality paper, kraft paper, and white clay coated paper, synthetic paper such as Yupo, polyethylene film, polypropylene film such as CPP or OPP, and poly-pair Polyester film such as ethylene phthalate film, polyimide film, polyimide film, polylactic acid film, polyphenol film, polycarbonate film, etc. Moreover, you may use the manufacturing papers, such as artificial leather, a ceramic sheet, a double-sided release paper, as a base material. In order to improve the adhesion between these substrates and the release layer, a corona treatment, an etching treatment, a primer treatment or a plasma treatment may be used on the substrate surface.

[Release sheet] In the present invention, the polyethylene laminate paper substrate was coated with the above-mentioned heavy release composition 0.9 to 1.2 g / m ² , and the release sheet was produced by heating at 140 ° C. for 30 seconds by the FINAT test method. The measured peeling force was 5 to 20 N / 25 mm. This makes it possible to use a release material having a high re-peeling effect. In addition, the change of the peeling force with time is small, and it is also a feature of the release sheet of the present invention. In addition, in this invention, "heavy peeling composition" means the thing which has the said peeling force by the said measuring method.

[Initial peeling force measurement method] (1) After the peeling sheet obtained by the hardening method was stored at 25 ° C for 24 hours, the peeling force measured by the FINAT test method in the same manner as above was used as the initial peeling force. In the present invention, it is preferably 5 to 15 N / 25 mm. The details of the measurement method are those described in the examples.

[Measurement method of peeling force with time] After the peeling sheet obtained by the above curing method was stored at 50 ° C. for 7 days, the peeling force measured by the FINAT test method in the same manner as above was used as the peeling force with time. In the present invention, it is preferably 5 to 15 N / 25 mm. The details of the measurement method are those described in the examples. [Example]

Hereinafter, synthesis examples, examples, and comparative examples are shown to specifically explain the present invention, but the present invention is not limited to the following examples.

[Synthesis Example 1] Preparation of platinum catalyst A reaction product of hexachloroplatinic acid and 1,3-divinyltetramethyldisilazane was used so that the platinum content became 0.5% by mass and the viscosity was 400 mPa. s. Average molecular formula: ViMe ₂ SiO (SiMe ₂ O) ₁₅₀ SiMe ₂ Vi linear dimethylpolysiloxane is diluted to prepare the platinum catalyst (catalyst (D) used in this example and comparative example). ). Me represents a methyl group, and Vi represents a vinyl group.

The raw materials used in the examples are described below. (A) Average molecular formula: The organopolysiloxane (B-1) represented by ViMe ₂ SiO (SiMe ₂ O) ₁₄ SiMe ₃ is composed of Me ₃ SiO _1/2 , ViMe ₂ SiO _1/2, and SiO _4/2 units. With respect to SiO _4/2 , the molar ratio of Me ₃ SiO _1/2 and ViMe ₂ SiO _1/2 is 0.8, and the amount of vinyl groups is 0.085 mol / 100 g of the organic polysiloxane resin relative to the solid content ( Solid at 25 ° C) (B-2-1) Average molecular formula: ViMe ₂ SiO (SiMe ₂ O) ₈ SiMe ₂ Vi Organopolysiloxane (liquid at 25 ° C) (B-2-2) Average molecular formula: ViMe ₂ SiO (SiMe ₂ O) ₁₅₀ SiMe ₂ Vi Organopolysiloxane (liquid at 25 ° C) (C-1-1) Average molecular formula: Me ₃ SiO (SiHMeO) ₄₆ SiMe ₃ the methyl hydrogen siloxane silicon (C-1-2) average molecular _{formula: Me 3 SiO (SiHMeO) 100} SiMe 3 represents the methyl hydrogen siloxane silicon (C-1-3) average molecular formula: Me ₃ SiO (SiHMeO) ₄₅ (SiMe ₂ O) ₁₇ Methylhydrosiloxane (C-2-1) average molecular formula represented by SiMe ₃ : HMe ₂ SiO (SiMe ₂ O) ₈ Methylhydrosiloxane represented by SiMe ₂ H (C- 2-2) Average molecular formula: HMe ₂ SiO (SiMe ₂ O) ₆₀ SiMe ₂ H methylhydrosilane (D) Modified platinum catalyst (E) 1-ethynylcyclohexanol obtained in Example 1 (Addition reaction control agent) (F) 1,3,5,7-tetramethyltetravinyltetracyclosiloxane (H / Vi modifier)

[Example 1] (1) The average molecular formula: ViMe ₂ SiO (SiMe ₂ O) ₁₄ SiMe ₃ represented by a single-end vinyl-terminated linear dimethylpolysiloxane (A), and Me ₃ SiO _1/2 , ViMe ₂ SiO _1/2, and SiO _4/2 units. The molar ratio of Me ₃ SiO _1/2 and ViMe ₂ SiO _1/2 is 0.8 relative to SiO _4/2 . Ingredients: The xylene solution of the organopolysiloxane resin (B-1) having a vinyl content of 0.085 mol / 100 g was mixed at a ratio of 10:50 in terms of the effective ingredient conversion mass ratio. In 60 parts by mass of the liquid, a mixed average molecular formula: ViMe ₂ SiO (SiMe ₂ O) ₈ SiMe ₂ Vi is represented by vinyl-terminated linear dimethylpolysiloxane (B-2-1 ) 13 parts by mass, average molecular formula: Me ₃ SiO (SiHMeO) ₄₆ 4.7 parts by mass of methyl hydrosiloxane (C-1-1) having SiH only in the side chain represented by SiMe ₃ , and average molecular formula: HMe ₂ SiO (SiMe ₂ O) ₈ SiMe ₂ H represents 8.5 parts by mass of methyl hydrosiloxane (C-2-1) having SiH at the end only. Xylene is removed under reduced pressure at 150 ° C and 20 mmHg to obtain transparency. Liquid (Molar ratio of total SiH groups with respect to total alkenyl groups in the composition, that is, H / Vi is 1.2). (2) In 100 parts by mass of the liquid, 0.2 part by mass of 1-ethynylcyclohexanol (component E) as an addition reaction control agent is uniformly mixed with 2 parts by mass of the platinum catalyst (D) obtained in Synthesis Example 1. To obtain a transparent composition with a viscosity of 890 mPa ･ s.

[Examples 2 to 12, Comparative Examples 1 to 8] Hereinafter, the components (A), (B), and (C) were mixed in the same manner as in Example 1 and removed under reduced pressure to remove (B-1) The xylene in the components was mixed with other components (F), the (E) component of the addition reaction control agent, and the platinum catalyst (D) obtained in Synthesis Example 1 as necessary to obtain the heavy peeling composition shown. The blending amount (unit: part by mass) is shown in the following table. In addition, in the table, the total amount of (A) component content / (A) component and (B) component represents the ratio of (A) component to 100 mass parts of the total of (A) component and (B) component. Content (parts by mass); (B-2) / (B-1) means (B-2) component content (parts by mass) / (B-1) component content (parts by mass); (C-2) / (C -1) indicates (C-2) component content (parts by mass) / (C-1) component content (parts by mass).

With respect to the composition obtained as described above, the viscosity (absolute viscosity measured by a B-type rotary viscometer at 25 ° C.) was measured, and a release sheet was further prepared by the following method to evaluate the peeling force. The results obtained are shown in the table. "Z" in the table indicates a tearing sound. The peeling force maintenance ratio [%] is a value obtained from the time-dependent peeling force / initial peeling force × 100 [%].

FIG. 1 shows the measurement results of the peeling force at the time of a tear sound, and FIG. 2 shows the measurement results of the usual peeling force without a tear sound. As shown in FIG. 1, the peeling force is unstable when there is a tearing sound, and it is difficult to measure the correct peeling force.

[Hardening method of heavy peeling composition] After preparing the heavy peeling composition, apply the heavy peeling composition on the polyethylene laminate paper substrate to 0.9 to 1.2 g / m ² and heat in a hot air dryer at 140 ° C. For 30 seconds, this was used as a release sheet for the following measurement.

[Measurement method of initial peeling force] After the release sheet obtained by the above curing method was stored at 25 ° C for 24 hours, a 25mm-width acrylic adhesive tape Tesa7475 (trade name of Tesa Tape. Inc.) was attached and dried at 70 ° C. A load of 20 g / cm ² was applied to the machine and taken out 24 hours later as a sample. After air cooling for about 30 minutes, the Tesa7475 tape of the sample was peeled off using a tensile tester (DSC-500 type tester manufactured by Shimadzu Corporation) at an angle of 180 ° at 0.3 m / min. force.

[Measurement method of peeling force with time] After the release sheet obtained by the above curing method was stored at 50 ° C for 7 days, a 25 mm-width acrylic adhesive tape Tesa7475 (trade name of Tesa Tape. Inc.) was pasted. A load of 20 g / m ² was applied to a dryer at 70 ° C. and stored for 24 hours as a sample. After air-cooling for about 30 minutes, the TESA-7475 tape of the sample was peeled off using a tensile tester (DSC-500 type tester manufactured by Shimadzu Corporation) at an angle of 180 ° at 0.3 m / min. Needed.

From the above results, it can be seen that the heavy peeling composition (Examples 1 to 12) of the present invention has high fluidity at 25 ° C, and its peeling sheet has a high peeling force of 5N / 25mm or more in the initial stage, and after time It also has a peeling force of 85% or more relative to the initial stage. In addition, no tearing sound occurred during the initial and after the peeling. Therefore, the heavy release composition of the present invention is useful as a release sheet for heavy release.

On the other hand, when the amount of the (A) component is increased (Comparative Example 2), and when the (C-1) component is decreased and the (C-2) component is increased (Comparative Examples 7, 8), the crosslink density is reduced and becomes lighter. Peeling release sheet. In contrast, when the component (A) is not included (Comparative Example 1), when the component (B-2) is not included (Comparative Example 3), when the component (C-1) is increased and the component (C-2) is decreased (Comparative Example) 5, 6), the crosslinking density increased excessively, and a tearing sound occurred during peeling. In addition, when the component (B-2) is increased as in Comparative Example 4, the viscosity of the composition becomes too low, resulting in a failure to smoothly coat the substrate. From the above results, it can be considered that the compositions shown in Comparative Examples 1 to 8 are not suitable for the above-mentioned applications.

The present invention is not limited to the embodiments described above. The above-mentioned embodiment is an example, and it has a structure substantially the same as the technical idea described in the patent application scope of the present invention, and exhibits the same effect, regardless of which is included in the technical scope of the present invention.

[Figure 1] Peeling force measurement results at the time of a tear sound. [Fig. 2] The result of the usual peeling force measurement without a tearing sound.

Claims (8)

A heavy release composition for a release sheet, which contains (A) the following general formula (1): (In the formula, R ¹ is an alkenyl group, and R ² is an unsubstituted or substituted monovalent hydrocarbon group not containing an alkenyl group, and a is a positive number satisfying 1 ≦ a ≦ 200.) Single-end reactive organic polysiloxane: 10 to 35 parts by mass based on the total amount of the components (A) and (B), (B) the following average composition formula (2): (In the formula, R ³ is an unsubstituted or substituted monovalent hydrocarbon group, and b is a positive number satisfying 0 ≦ b ≦ 3.) An organic polysiloxane having at least two alkenyl groups in one molecule represented by: For a total of 100 parts by mass of the components (A) and (B), the component (B) is 65 to 90 parts by mass, and (C) the following average composition formula (3): (In the formula, R ⁴ is independently an unsubstituted or substituted monovalent hydrocarbon group containing no alkenyl group, and c and d are those satisfying 0.7 ≦ c ≦ 2.1, 0.001 ≦ d ≦ 1.0, and 0.8 ≦ c + d ≦ 3.0. (Positive number) An organohydrogenpolysiloxane having at least two hydrogen atoms bonded to a silicon atom in one molecule: (C) For all alkenyl groups in the components (A) and (B) The amount of hydrogen atoms bonded to the silicon atom in the component is 0.5 to 5.0 times the mole. (D) Platinum group metal catalyst: an effective amount of a heavy peeling composition for a release sheet, wherein the component (B) is An organic polysiloxane resin (B-1) having at least 2 alkenyl groups in a molecule and having a three-dimensional network structure at 25 ° C is waxy or solid, and has at least 2 at the end which is liquid at 25 ° C. Combination of linear or branched organopolysiloxanes (B-2) of alkenyl groups, the mass ratio of (B-1) component to (B-2) component (B-2) / (B- 1) is 0.1 to 0.5, and the component (C) is an organohydrogenpolysiloxane (C-1) having a hydrogen atom bonded to a silicon atom in a side chain, and has an end and a side chain without a bond The combination of organohydrogen polysiloxane (C-2) with silicon atom and hydrogen atom, The mass ratio (C-2) / (C-1) of the (C-1) component to the (C-2) component is 1 to 5. The heavy release composition for a release sheet according to claim 1, wherein the component (B-1) is the following average composition formula (4): (In the formula, R ⁵ independently represents an alkenyl group, and R ⁶ independently represents an unsubstituted or substituted monovalent hydrocarbon group containing no alkenyl group, but at least 80 mole% of all R ⁶ is methyl, e, f , G, h, i, j, and k are numbers that satisfy e ≧ 0, f ≧ 0, g ≧ 0, h ≧ 0, i ≧ 0, j ≧ 0, and k ≧ 0, respectively, but satisfy f + g + i> 0, i + j + k> 0, (e + f + g + h) / (i + j + k) <1.3, and e + f + g + h + i + j + k = 1 (Number) represents an organic polysiloxane resin having at least two alkenyl groups in a molecule and having a three-dimensional network structure at 25 ° C, which is waxy or solid. The heavy release composition for a release sheet according to claim 1 or 2, wherein the above (B-2) is the following average composition formula (5): (In the formula, R ⁷ independently represents an alkenyl group, and R ⁸ independently represents an unsubstituted or substituted monovalent hydrocarbon group containing no alkenyl group, but at least 80 mole% of all R ⁸ is methyl, l, m , N, p, and q are numbers satisfying l ≧ 0, m> 0, n ≧ 0, p ≧ 0, and q ≧ 0, respectively, but satisfying n + p + q> 0, p + q <0.1 , And l + m + n + p + q = 1) means a linear or branched organic polysiloxane that is liquid at 25 ° C and has at least 2 alkenyl groups at the end. The heavy release composition for a release sheet according to claim 1 or 2, wherein the component (C-1) is the following average composition formula (6): (In the formula, R ⁹ independently represents an unsubstituted or substituted monovalent hydrocarbon group containing no alkenyl group, and r, s, t, u, v, w, and x are those satisfying r ≧ 0, s ≧ 0, t ≧ 0, u ≧ 0, v ≧ 0, w ≧ 0, and x ≧ 0, except that it satisfies t + v> 0 and s + t + u + v + w + x + y = 1 An organohydrogenpolysiloxane represented by a side chain having a hydrogen atom bonded to a silicon atom. The heavy release composition for a release sheet according to claim 1 or 2, wherein the component (C-2) is the following average composition formula (7): (In the formula, R ¹⁰ independently represents an unsubstituted or substituted monovalent hydrocarbon group containing no alkenyl group, α, β, γ, δ, and ε, respectively, satisfying α ≧ 0, β> 0, and γ ≧ 0. , Δ ≧ 0 and ε ≧ 0, but satisfying γ + δ + ε> 0, δ + ε <0.1, and α + β + γ + δ + ε = 1) represent that the end has and side An organohydrogenpolysiloxane that does not have a hydrogen atom bonded to a silicon atom. The heavy-peeling composition for the release sheet of claim 1 or 2, wherein the viscosity at 25 ° C is 50 to 2,000 mPa ･ s. A release sheet comprising a flaky substrate and a hardened film of a heavy release composition for a release sheet according to any one of claims 1 to 6 on one or both sides of a surface of the substrate. The peeling sheet according to claim 7, wherein a Tesa7475 tape is attached to the cured film, and the peeling force measured at an angle of 180 ° and a peeling speed of 0.3 m / min is 5 to 20 N / 25 mm.