WO2018131490A1 - 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 an addition reaction curable heavy release composition for release sheet that gives an excellent heavy release effect, and a release sheet using the same.

Conventionally, in order to prevent adhesion and adhesion between a base material such as paper or plastic and an adhesive material, a cured film of an organopolysiloxane composition is formed on the base material surface to impart release characteristics. As a method of forming a cured organopolysiloxane film on the above-mentioned substrate surface, the peelable film formation method by addition reaction is excellent in curability and can respond to various peel characteristics requirements from low speed peel to high speed peel. Therefore, it is widely used.

The method for forming a peelable film by this addition reaction includes a type in which an organopolysiloxane composition is dissolved in an organic solvent, a type in which the composition is dispersed in water using an emulsifier, and a solventless type consisting only of an organopolysiloxane. However, since the solvent type has a drawback that it may be harmful to the human body and the environment, switching from the solvent type to the solventless type is progressing from the viewpoint of safety.

In general, organopolysiloxane compositions for release paper are required to have various peeling forces depending on the purpose. For applications requiring heavy peeling, an alkenyl group-containing MQ resin (What is M unit?) R ′ ₃ SiO _1/2 units and Q units mean SiO _4/2 units, and R ′ represents a monovalent hydrocarbon group, the same shall apply hereinafter).

However, the alkenyl group-containing MQ resin is often a resinous or highly viscous compound, and when added in a large amount, it cannot be used unless it is diluted in an organic solvent. Further, if it is added in a small amount, it can be used without a solvent, but in such a case, the heavy peeling effect is insufficient. Further, it is known that the alkenyl group-containing MQ resin has a tendency that the peeling force decreases with time as compared with the peeling force immediately after curing, and a resin having no change in peeling force with time is required.

On the other hand, when the tape is peeled from the heavy release sheet, peeling sound (zipping) may be a problem. Although there are many unclear parts regarding the detailed mechanism of zipping, there is a tendency that zipping is likely to occur particularly in a highly-peeled sheet with high crosslink density. Therefore, in developing a heavy release sheet, suppression of zipping is also an important issue.

Japanese Patent Publication No. 5-53183 (Patent Document 1) is a combination of an alkenyl group-containing MQ resin and an alkenyl group-free MQ resin in an organopolysiloxane composition for release paper, and the change in peel force over time. However, the effect of heavy peeling is insufficient.

Japanese Patent No. 2750896 (Patent Document 2) is a composition in which an alkenyl group-containing resin is blended in an organopolysiloxane composition for a solvent-type addition reaction type release paper, and low temperature curability and a peeling force with little change with time are obtained. However, heavy peeling is not the purpose and the peeling force is not large. Furthermore, the following technique has been reported as a method for performing heavy release by adding an organopolysiloxane resin having adhesiveness to an addition reaction type organopolysiloxane composition.

Japanese Patent Publication No. 6-086582 (Patent Document 3) is an adhesive organopolysiloxane protective coating having a partially dehydrated condensation of a curable silicone rubber, an organopolysiloxane having hydroxyl groups at both ends and an MQ unit-containing silicone resin. . Since these silicone rubbers and silicone resins are highly viscous or solid, a solvent is required.

Japanese Patent Laid-Open No. 10-110156 (Patent Document 4) is a technique relating to an organopolysiloxane pressure-sensitive adhesive mainly composed of a mixture or partial condensate of vinyl raw rubber and MQ resin. This uses a silicone rubber and requires a solvent, and does not touch the effect as a heavy release composition for release paper.

In JP-A 2010-37557 (Patent Document 5), the molar ratio of (a1) M unit to Q unit is 0.6 to 1.0, and the hydroxyl group or alkoxy group content is 0.3 to 2. Organopolysiloxane obtained by condensation reaction of 100 parts by mass of MQ resin in the range of 0% by mass and (a2) 20 to 150 parts by mass of a linear polydiorganosiloxane having an average polymerization degree of 100 to 1,000 having a hydroxyl group or an alkoxy group It is a release modifier comprising a resin-organopolysiloxane condensation reaction product. According to Patent Document 6, the peeling force in the examples is only 1.4 times to 2.2 times at a low speed (0.3 m / min) compared with the comparative example without addition of the condensation reaction product, which is sufficient. The heavy peeling effect is not obtained. This is because the content of the hydroxyl group or alkoxy group of (a1) used is as low as 0.3 to 2.0% by mass, there are few reaction points with (a2), and it has a crosslinked structure by sufficient condensation. This is presumed to be because there is not.

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

JP-A-6-228501 (Patent Document 7) presents a method of increasing the peel strength of a pressure-sensitive adhesive without using an alkenyl group-containing MQ resin. This is a composition in which the crosslink density is adjusted by using a higher alkenyl group at the crosslink site, but the zipping is not mentioned, and since the alkenyl group-containing MQ resin is not used, the heavy peeling effect is insufficient. .

JP-A-7-188562 (Patent Document 8) is a heavy release composition using an alkenyl group-containing MQ resin, α, ω-diolefin, and organohydrogenpolysiloxane. Although an alkenyl group-containing MQ resin and α, ω-diolefin have a very high peeling force, no problem has been raised about zipping, and a means to solve this problem has also been suggested. Absent.

Japanese Examined Patent Publication No. 5-53183 Japanese Patent No. 2750896 Japanese Patent Publication No. 6-086582 Japanese Patent Laid-Open No. 10-110156 JP 2010-37557 A JP-A-5-329184 JP-A-6-228501 JP-A-7-188562

The present invention has been made in view of the above circumstances, and is excellent in a heavy peeling effect, suppresses zipping at the time of peeling, and further reduces the peeling force over time after curing, and a heavy release composition for a release sheet, and curing thereof. It aims at providing the peeling sheet in which the membrane | film | coat was formed.

As a result of intensive studies to achieve the above object, the present inventors have found that (A) one-terminal reactive organopolysiloxane having one alkenyl group at the terminal and (B) at least 2 in one molecule. In a composition comprising an organopolysiloxane having a plurality of alkenyl groups, (C) an organohydrogenpolysiloxane having at least two hydrogen atoms bonded to a silicon atom in one molecule, and (D) a platinum group metal catalyst, The amount of the component (A) with respect to the total amount of the components (A) and (B) is in a specific range, and in the component (B), the organopolysiloxane resin (B-1) having a three-dimensional network structure and Organohigh having a hydrogen atom bonded to a silicon atom in the side chain in a specific mass ratio, (C) component, with a chain- or branched-chain organopolysiloxane (B-2) By making the specific mass ratio between the hydrogen polysiloxane (C-1) and the organohydrogenpolysiloxane (C-2) having a hydrogen atom bonded to a silicon atom at the terminal and not in the side chain. The resulting composition was found to be excellent in the heavy peeling effect, suppressed zipping at the time of peeling, and further reduced in the peeling force with time after curing, and led to the present invention.

Accordingly, the present invention provides the following inventions.
[1]. (A) The following general formula (1):

(Wherein R ¹ represents an alkenyl group, R ² independently represents an unsubstituted or substituted monovalent hydrocarbon group not containing an alkenyl group, and a is a positive number satisfying 1 ≦ a ≦ 200.)
One-terminal reactive organopolysiloxane having one alkenyl group at the end represented by the formula: 10 to 35 parts by mass with respect to the total amount of component (A) and component (B) (B) 2):
R ³ _b SiO _{(4-b) / 2} (2)
(Wherein R ³ is independently an unsubstituted or substituted monovalent hydrocarbon group, and b is a positive number satisfying 0 ≦ b ≦ 3). Organopolysiloxane having an alkenyl group: 65 to 90 parts by mass of component (B) with respect to 100 parts by mass in total of component (A) and component (B) (C) The following average composition formula (3):
R ⁴ _c H _d SiO _{(4-cd) / 2} (3)
(In the formula, R ⁴ is an unsubstituted or substituted monovalent hydrocarbon group which does not contain an alkenyl group independently, and c and d are 0.7 ≦ c ≦ 2.1, 0.001 ≦ d ≦ 1. 0 and a positive number satisfying 0.8 ≦ c + d ≦ 3.0.)
An organohydrogenpolysiloxane having at least two hydrogen atoms bonded to a silicon atom represented by the formula: in the component (C) with respect to all alkenyl groups in the components (A) and (B) An amount in which hydrogen atoms bonded to silicon atoms are 0.5 to 5.0 times mol,
(D) platinum group metal catalyst: a heavy release composition for a release sheet containing an effective amount,
The component (B) has an organopolysiloxane resin (B-1) having a three-dimensional network structure having at least two alkenyl groups in one molecule and being waxy or solid at 25 ° C., and at 25 ° C. It is a combination of a linear or branched organopolysiloxane (B-2) having at least two alkenyl groups at the terminals, which is liquid, and comprises (B-1) and (B-2) The mass ratio (B-2) / (B-1) is 0.1 to 0.5, and
The component (C) has an organohydrogenpolysiloxane (C-1) having a hydrogen atom bonded to a silicon atom in the side chain, and a hydrogen atom bonded to a silicon atom at the terminal and not in the side chain. Release sheet which is a combination of organohydrogenpolysiloxane (C-2) and has a mass ratio (C-2) / (C-1) of components (C-1) to (C-2) of 1 to 5 Heavy release composition.
[2]. The component (B-1) has the following average composition formula (4):
(R ⁶ ₃ SiO _1/2 ) _e (R ⁵ R ⁶ ₂ SiO _1/2 ) _f (R ⁵ R ⁶ SiO) _g (R ⁶ ₂ SiO) _h (R ⁵ SiO _3/2 ) _i (R ⁶ SiO _3/2 ) _j (SiO _4/2 ) _k (4)
(In the formula, R ⁵ independently represents an alkenyl group, R ⁶ independently represents an unsubstituted or substituted monovalent hydrocarbon group not containing an alkenyl group, provided that at least 80 mol% of all R ⁶ is a methyl group. Yes, e, f, g, h, i, j and k are numbers satisfying e ≧ 0, f ≧ 0, g ≧ 0, h ≧ 0, i ≧ 0, j ≧ 0 and k ≧ 0, respectively. Yes, provided that 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.
The release sheet for release sheet according to [1], which is an organopolysiloxane resin having a three-dimensional network structure which is waxy or solid at 25 ° C. and has at least two alkenyl groups in one molecule Composition.
[3]. The above (B-2) is the following average composition formula (5):
(R ⁸ ₃ SiO _1/2 ) _l (R ⁷ R ⁸ ₂ SiO _1/2 ) _m (R ⁸ ₂ SiO) _n (R ⁸ SiO _3/2 ) _p (SiO _4/2 ) _q (5) )
(Wherein R ⁷ independently represents an alkenyl group, R ⁸ independently represents an unsubstituted or substituted monovalent hydrocarbon group not containing an alkenyl group, provided that at least 80 mol% of all R ⁸ is a methyl group. L, m, n, p and q are numbers satisfying l ≧ 0, m> 0, n ≧ 0, p ≧ 0 and q ≧ 0, respectively, provided that n + p + q> 0, p + q <0. 1 and a number satisfying l + m + n + p + q = 1.)
The heavy release composition for release sheets according to [1] or [2], which is a linear or branched organopolysiloxane having at least two alkenyl groups at the ends, which is liquid at 25 ° C. object.
[4]. The component (C-1) is the following average composition formula (6):
(R ⁹ ₃ SiO _1/2 ) _r (R ⁹ ₂ HSiO _1/2 ) _s (R ⁹ HSiO) _t (R ⁹ ₂ SiO) _u (HSiO _3/2 ) _v (R ⁹ SiO _3/2 ) _w ( SiO _4/2 ) _x (6)
(Wherein R ⁹ independently represents an unsubstituted or substituted monovalent hydrocarbon group not containing an alkenyl group, and r, s, t, u, v, w and x are r ≧ 0 and s ≧, respectively. 0, t ≧ 0, u ≧ 0, v ≧ 0, w ≧ 0 and x ≧ 0, provided that t + v> 0 and s + t + u + v + w + x + y = 1.)
The heavy release composition for release sheets according to any one of [1] to [3], which is an organohydrogenpolysiloxane having a hydrogen atom bonded to a silicon atom in its side chain, represented by:
[5]. The component (C-2) has the following average composition formula (7):
(R ¹⁰ ₃ SiO _1/2 ) _α (R ¹⁰ ₂ HSiO _1/2 ) _β (R ¹⁰ ₂ SiO) _γ (R ¹⁰ SiO _3/2 ) _δ (SiO _4/2 ) _ε (7)
(Wherein R ¹⁰ independently represents an unsubstituted or substituted monovalent hydrocarbon group not containing an alkenyl group, and α, β, γ, δ, and ε are α ≧ 0, β> 0, γ, respectively. ≧ 0, δ ≧ 0, and ε ≧ 0, provided that γ + δ + ε> 0, δ + ε <0.1, and α + β + γ + δ + ε = 1.)
The heavy release composition for release sheets according to any one of [1] to [4], which is an organohydrogenpolysiloxane having a hydrogen atom bonded to a silicon atom at its terminal and having no side chain object.
[6]. The heavy release composition for release sheets according to any one of [1] to [5], wherein the viscosity at 25 ° C. is 50 to 2,000 mPa · s.
[7]. A release sheet having a sheet-like base material and a cured film of the heavy release composition for release sheet according to any one of [1] to [6] on one or both surfaces of the surface of the base material.
[8]. The release sheet according to [7], wherein a Tesa 7475 tape is attached to the cured film, and the peel force measured at an angle of 180 ° and a peel speed of 0.3 m / min is 5 to 20 N / 25 mm.

The heavy release composition for release sheet of the present invention can obtain a very large release force even when compared with conventional heavy release compositions. Moreover, since zipping at the time of peeling is suppressed and the decrease in peeling force with time after curing is small, it is useful as a material for a release sheet for heavy peeling.

It is a peeling force measurement result at the time of zipping. It is a normal peel force measurement result that is not zipped.

Hereinafter, the present invention will be described in detail.
[(A) component]
The component (A) is represented by the following general formula (1):

(In the formula, R ¹ is an alkenyl group, R ² is an unsubstituted or substituted monovalent hydrocarbon group that does not contain an alkenyl group, and a is a positive number that satisfies 1 ≦ a ≦ 200.)
It is a one-terminal reactive organopolysiloxane having one alkenyl group at the end, represented by: By using this one-terminal reactive organopolysiloxane having one alkenyl group at the end of component (A) to adjust the crosslinking density, the release sheet heavy release composition (hereinafter referred to as the heavy release composition) of the present invention. It is possible to provide a release sheet without zipping. In addition, (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 is usually 2 to 8, preferably 2 to 4. Specific examples include vinyl group, allyl group, butenyl group, pentenyl group, hexenyl group, heptenyl group and the like, and vinyl group is preferable.

R ² is 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, a monovalent hydrocarbon group of 1 to 12, preferably 1 to 10, is mentioned. Examples of the unsubstituted or substituted monovalent hydrocarbon group include alkyl groups such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, and a heptyl group; a cycloalkyl group such as a cyclohexyl group; Aryl groups such as a group, tolyl group, xylyl group and naphthyl group; aralkyl groups such as a benzyl group and a phenethyl group; some or all of hydrogen atoms of these groups are halogen atoms such as a chlorine atom, a fluorine atom and a bromine atom Examples thereof include halogenated alkyl groups such as substituted chloromethyl group, 3-chloropropyl group, and 3,3,3-trifluoropropyl group. Of these, an alkyl group is preferable, and a methyl group is more preferable.

A is a positive number satisfying 1 ≦ a ≦ 200, preferably 5 ≦ a ≦ 100, more preferably a positive number satisfying 5 ≦ a ≦ 30. When a exceeds 200, since the component (A) works as a light release component, it is difficult to obtain a target heavy release effect. Moreover, the viscosity of a composition becomes high and the problem that it cannot be used unless diluted with a solvent also arises.

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

The content of the component (A) is 10 to 35 parts by mass with respect to 100 parts by mass in total of the components (A) and (B). When the content of the component (A) is less than 10 parts by mass, the crosslink density of the cured product becomes high, causing a problem that zipping occurs. Moreover, when content of (A) component exceeds 35 mass parts, since the crosslinking density of hardened | cured material will be reduced more than needed, it will become difficult to obtain the target heavy peeling effect.

[Component (B)]
The component (B) has the following average composition formula (2):
R ³ _b SiO _{(4-b) / 2} (2)
(Wherein R ³ is independently an unsubstituted or substituted monovalent hydrocarbon group, and b is a positive number satisfying 0 ≦ b ≦ 3). An organopolysiloxane having an alkenyl group. (B) A component can be used individually by 1 type or in combination of 2 or more types.

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

The alkenyl groups in component (B), specifically the same thing can be mentioned those exemplified as R ¹ in the formula (1) of the component (A), among others vinyl group is preferable. Examples of the unsubstituted or substituted monovalent hydrocarbon group other than the alkenyl group in the component (B) include the same as those specifically exemplified as R ^{2 in} the general formula (1) of the component (A). Of these, an alkyl group is preferable, and a methyl group is more preferable.

In the present invention, the component (B) comprises an organopolysiloxane resin (B-1) having a three-dimensional network structure having a waxy shape or a solid shape at 25 ° C. having at least two alkenyl groups in one molecule; A combination of a linear or branched organopolysiloxane (B-2) having at least two alkenyl groups at its terminal, which is liquid at 25 ° C., and comprises (B-1) component and (B-2) The mass ratio (B-2) / (B-1) to component is 0.1 to 0.5.

[(B-1) component]
The term “wax” means a gum shape (raw rubber shape) of 10,000 Pa · s or more, particularly 100,000 Pa · s or more at 25 ° C., which hardly exhibits self-fluidity. In addition, the measurement of a viscosity is the value (henceforth the same) of the absolute viscosity measured with a B-type rotational viscometer at 25 degreeC.

(B-1) includes the following average composition formula (4):
(R ⁶ ₃ SiO _1/2 ) _e (R ⁵ R ⁶ ₂ SiO _1/2 ) _f (R ⁵ R ⁶ SiO) _g (R ⁶ ₂ SiO) _h (R ⁵ SiO _3/2 ) _i (R ⁶ SiO _3/2 ) _j (SiO _4/2 ) _k (4)
(In the formula, R ⁵ independently represents an alkenyl group, R ⁶ independently represents an unsubstituted or substituted monovalent hydrocarbon group not containing an alkenyl group, provided that at least 80 mol% of all R ⁶ is a methyl group. Yes, e, f, g, h, i, j and k are numbers satisfying e ≧ 0, f ≧ 0, g ≧ 0, h ≧ 0, i ≧ 0, j ≧ 0 and k ≧ 0, respectively. Yes, provided that 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.
In the molecule, at least two alkenyl groups bonded to a silicon atom and a trifunctional siloxane unit and / or SiO _4/2 unit are essential.

In the average composition formula (4), examples of the alkenyl group represented by R ⁵ are the same as those specifically exemplified as R ¹ in the formula (1) of the component (A). preferable. Examples of the unsubstituted or substituted monovalent hydrocarbon group other than the alkenyl group represented by R ⁶ are the same as those specifically exemplified as R ² in the formula (1) of the component (A). At least 80 mol% of R ⁵ is a methyl group. When the proportion of methyl groups is less than 80 mol% of the total R ⁵ , the composition is inferior in compatibility with the component (A), so that the composition may become cloudy and a uniform film may not be obtained.

e is 0 to 0.65, f is 0 to 0.65, g is 0 to 0.5, h is 0 to 0.5, i is 0 to 0.8, j is 0 to 0.8, k is A number of 0 to 0.6 is preferred. Further, f + g + i is preferably a number of 0.1 to 0.8, i + j + k is preferably a number of 0.1 to 0.8, particularly preferably 0.2 to 0.6, and (e + f + g + h) / ( i + j + k) is preferably a number from 0.6 to 1.25.

Examples of the organopolysiloxane resin represented by the average composition formula (4) include the following.
(Me ₃ SiO _1/2 ) _e (ViMe ₂ SiO _1/2 ) _f (SiO _4/2 ) _k
(ViMe ₂ SiO _1/2 ) _f (SiO _4/2 ) _k
(ViMeSiO) _g (Me ₂ SiO) _h (MeSiO _3/2 ) _j
(ViMe ₂ SiO _1/2 ) _f (Me ₂ SiO) _h (ViSiO _3/2 ) _i
(ViMe ₂ SiO _1/2 ) _f (Me ₂ SiO) _h (MeSiO _3/2 ) _j
(Me ₃ SiO _1/2 ) _e (ViMe ₂ SiO _1/2 ) _f (Me ₂ SiO) _h (MeSiO _3/2 ) _j
(Me ₃ SiO _1/2 ) _e (ViMe ₂ SiO _1/2 ) _f (Me ₂ SiO) _h (ViMeSiO) _g (MeSiO _3/2 ) _j
(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 average composition formula (4).)
In particular, it is more preferable to use an organopolysiloxane resin composed of Me ₃ SiO _1/2 , ViMe ₂ SiO _1/2 and SiO _4/2 units. By using such an organopolysiloxane resin, the resulting cured product has a sufficiently high crosslinking density, and a desired heavy peeling effect can be obtained.

[(B-2) component]
The linear or branched organopolysiloxane having at least two alkenyl groups at the terminal, which is liquid at 25 ° C., has the following average composition formula (5):
(R ⁸ ₃ SiO _1/2 ) _l (R ⁷ R ⁸ ₂ SiO _1/2 ) _m (R ⁸ ₂ SiO) _n (R ⁸ SiO _3/2 ) _p (SiO _4/2 ) _q (5) )
(Wherein R ⁷ independently represents an alkenyl group, R ⁸ independently represents an unsubstituted or substituted monovalent hydrocarbon group not containing an alkenyl group, provided that at least 80 mol% of all R ⁸ is a methyl group. L, m, n, p and q are numbers satisfying l ≧ 0, m> 0, n ≧ 0, p ≧ 0 and q ≧ 0, respectively, provided that n + p + q> 0, p + q <0. 1 and a number satisfying l + m + n + p + q = 1.)
The compound represented by these is mentioned.

In the average composition formula (5), examples of the alkenyl group represented by R ⁷ are the same as those specifically exemplified as R ¹ in the formula (1) of the component (A). preferable. The unsubstituted or substituted monovalent hydrocarbon group other than the alkenyl group represented by R ⁸ is the same as that specifically exemplified as R ² in the formula (1) of the component (A). At least 80 mol% of all R ⁸ are methyl groups. When the ratio of methyl groups is less than 80 mol% of the total R ⁸ , the composition is inferior in compatibility with the component (A), so that the composition may become cloudy and a uniform film may not be obtained.

It is preferable that l is 0 to 0.65, m is 0.01 to 0.65, n is 0 to 1, p is 0 to 0.1, and q is 0 to 0.1. Further, n + p + q is preferably a number of 0.5 to 1, particularly 0.7 to 1, and p + q is preferably a number of less than 0.1. When p + q exceeds 0.1, the crosslink density of the cured product becomes high, causing a problem that zipping occurs.
As a specific example of the average composition formula (5),

A linear polysiloxane represented by:

The branched polysiloxane etc. which are represented by these are mentioned. Among these, it is more preferable to use a linear organopolysiloxane composed of ViMe ₂ SiO _1/2 and Me ₂ SiO units. By using such an organopolysiloxane, it becomes easier to adjust the crosslinking density of the resulting cured product.

The viscosity of component (B) at 25 ° C. is preferably 1,000 mPa · s or less, more preferably 0.5 to 1,000 mPa · s, and even more preferably 2 to 500 mPa · s. When the viscosity exceeds 1,000 mPa · s, there is a problem that the viscosity of the composition becomes high and the composition cannot be used unless it is diluted with a solvent.

The ratio of the organopolysiloxane resin (B-1) having a three-dimensional network structure and the linear or branched organopolysiloxane (B-2) in the component (B) is also important for the composition of the present invention. One of the factors. That is, the mass ratio of the component (B-1) to the component (B-2) ((B-2) / (B-1)) needs to be 0.1 to 0.5. 4 is preferred. When (B-2) / (B-1) is less than 0.1, the crosslink density of the cured product becomes high and zipping occurs. Further, when (B-2) / (B-1) exceeds 0.5, it is difficult to obtain a target heavy peeling effect because the crosslinking density of the cured product is unnecessarily lowered. Become.

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

[Component (C)]
Component (C) has the following average composition formula (3):
R ⁴ _c H _d SiO _{(4-cd) / 2} (3)
(In the formula, R ⁴ is an unsubstituted or substituted monovalent hydrocarbon group which does not contain an alkenyl group independently, and c and d are 0.7 ≦ c ≦ 2.1, 0.001 ≦ d ≦ 1. 0 and a positive number satisfying 0.8 ≦ c + d ≦ 3.0.)
And an organohydrogenpolysiloxane having at least two hydrogen atoms bonded to a silicon atom in one molecule.

The component (C) serves as a crosslinking agent that reacts with the alkenyl group contained in the components (A) and (B) by a hydrosilylation reaction to cause crosslinking. From such a viewpoint, the viscosity of the component (C) is preferably 1,000 mPa · s or less, more preferably 0.5 to 1,000 mPa · s, even more preferably 2 to 200 mPa · s at 25 ° C. From the balance of crosslinking, the hydrogen atoms bonded to the silicon atoms in the component (C) are 0.5 to 5.0 mol times the total alkenyl groups in the components (A) and (B). Preferably, the amount is controlled to 0.7 to 3.0 mole times. If this amount does not satisfy the amount of 0.5 to 5.0 mole times, the balance of crosslinking may be inappropriate.

In the component (C), the content of hydrogen atoms bonded to the silicon atom is preferably in the range of 0.001 to 0.02 mol, and in the range of 0.002 to 0.017 mol, per gram of the component (C). It is more preferable that

In the average composition formula (3), the unsubstituted or substituted monovalent hydrocarbon group not containing the alkenyl group represented by R ⁴ is specifically exemplified as R ² in the formula (1) of the component (A). However, it is preferable that at least 50 mol%, typically 60 to 100 mol%, of the total R ⁴ is a methyl group. When the ratio of methyl groups is less than 50 mol% of the total R ⁴ , the compatibility with the component (A) and the component (B) is inferior, and there is a possibility that problems such as cloudiness or phase separation of the composition may occur. There is. c is a positive number satisfying 0.7 ≦ c ≦ 2.1, d is 0.001 ≦ d ≦ 1.0, and c + d is 0.8 ≦ c + d ≦ 3.0.

In the present invention, the component (C) includes an organohydrogenpolysiloxane (C-1) having a hydrogen atom bonded to a silicon atom in the side chain, and a hydrogen atom bonded to the silicon atom at the terminal and in the side chain. Is composed of a combination of organohydrogenpolysiloxane (C-2) that does not have. The component (C-1) is a component mainly for imparting adhesion to the substrate, and the component (C-2) is a component for adjusting the crosslinking density. (C) A component can be used individually by 1 type or in combination of 2 or more types as appropriate.

As (C-1), the following average composition formula (6):
(R ⁹ ₃ SiO _1/2 ) _r (R ⁹ ₂ HSiO _1/2 ) _s (R ⁹ HSiO) _t (R ⁹ ₂ SiO) _u (HSiO _3/2 ) _v (R ⁹ SiO _3/2 ) _w ( SiO _4/2 ) _x (6)
(Wherein R ⁹ independently represents an unsubstituted or substituted monovalent hydrocarbon group not containing an alkenyl group, and r, s, t, u, v, w and x are r ≧ 0 and s ≧, respectively. 0, t ≧ 0, u ≧ 0, v ≧ 0, w ≧ 0 and x ≧ 0, provided that t + v> 0 and s + t + u + v + w + x + y = 1.)
The compound represented by these is mentioned.

Examples of the unsubstituted or substituted monovalent hydrocarbon group other than the alkenyl group represented by R ⁹ are the same as those specifically exemplified as R ² in the formula (1) of the component (A), and alkyl. Group is preferred, and a methyl group is more preferred.

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

As a specific example of the average composition formula (6),

A cyclic organohydrogenpolysiloxane represented by

A linear organohydrogenpolysiloxane represented by:
(Me ₃ SiO _1/2 ) _r (MeHSiO) _t (SiO _4/2 ) _x
(Me ₂ HSiO _1/2 ) _s (MeHSiO) _t (Me ₂ SiO) _u (SiO _4/2 ) _x
(Me ₃ SiO _1/2 ) _r (MeHSiO) _t (MeSiO _3/2 ) _w
(Me ₃ SiO _1/2 ) _r (MeHSiO) _t (HSiO _3/2 ) _v
(MeHSiO) _t (MeSiO _3/2 ) _w
(Wherein, r, s, t, u, v, w and x are as defined in the above average composition formula (6).)
And branched organohydrogenpolysiloxanes represented by the formula: In particular, it is more preferable to use a linear organopolysiloxane 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 organopolysiloxane, it becomes possible to provide adhesion to the substrate.

(C-2) includes (R ¹⁰ ₃ SiO _1/2 ) _α (R ¹⁰ ₂ HSiO _1/2 ) _β (R ¹⁰ ₂ SiO) _γ (R ¹⁰ SiO _3/2 ) _δ (SiO _4/2 ) _ε (7)
(Wherein R ¹⁰ independently represents an unsubstituted or substituted monovalent hydrocarbon group not containing an alkenyl group, and α, β, γ, δ, and ε are α ≧ 0, β> 0, γ, respectively. ≧ 0, δ ≧ 0, and ε ≧ 0, provided that γ + δ + ε> 0, δ + ε <0.1, and α + β + γ + δ + ε = 1.)
).

Examples of the unsubstituted or substituted monovalent hydrocarbon group other than the alkenyl group represented by R ¹⁰ include those specifically exemplified as R ² in the formula (1) of the component (A). And a methyl group is more preferable.

Α is preferably a number from 0 to 0.65, β is from 0.01 to 0.65, γ is from 0 to 1, δ is from 0 to 0.1, and ε is a number from 0 to 0.1. Further, γ + δ + ε is preferably a number of 0.5 to 1, particularly 0.7 to 1, and δ + ε is preferably a number of less than 0.1. When δ + ε exceeds 0.1, the crosslink density of the cured product may be increased.

As a specific example of the average composition formula (7),

A linear organohydrogenpolysiloxane represented by:

And branched organohydrogenpolysiloxanes represented by the formula: In the above-described branched organohydrogenpolysiloxane structure, at least one of 0 to 60 indicating the number of each (CH ₃ ) ₂ SiO unit is 1 to 60, and at least 1 of 0 to 50 One is preferably 1-50. In particular, it is more preferable to use a linear organopolysiloxane composed of Me ₂ HSiO _1/2 and Me ₂ SiO units. By using such an organopolysiloxane, it is easy to adjust the crosslinking density of the resulting cured product.

The component (C) in which the hydrogen atom bonded to the silicon atom in the side chain is essential and the hydrogen atom bonded to the silicon atom at the terminal and on the side The proportion of the organohydrogenpolysiloxane (C-2) not present in the chain is also an important factor of the composition of the present invention. That is, the mass ratio ((C-2) / (C-1)) between the component (C-1) and the component (C-2) needs to be 1 to 5. When (C-2) / (C-1) is less than 1, the crosslink density of the cured product becomes high, causing a problem that zipping occurs. When (C-2) / (C-1) exceeds 5, the crosslink density of the cured product is unnecessarily lowered, making it difficult to obtain the target heavy peeling effect.

[(D): Platinum group metal catalyst]
The (D) component platinum group metal-based catalyst is a catalyst for promoting the addition reaction of the (A) component and the (B) component and the (C) component, and is known to those skilled in the art as promoting the so-called hydrosilylation reaction. Any known one can be used. Examples of such platinum group metal-based catalysts include platinum-based, palladium-based, rhodium-based, and ruthenium-based catalysts. Of these, platinum-based catalysts are particularly preferably used. Examples of the platinum-based catalyst include chloroplatinic acid, an alcohol solution or aldehyde solution of chloroplatinic acid, a complex of chloroplatinic acid with various olefins or vinyl siloxane, and the like. More specifically, a platinum catalyst obtained by modifying chloroplatinic acid with 1,3-divinyltetramethyldisiloxane can be mentioned.

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

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

・ Alkenyl group-containing compound other than components (A) and (B) In addition to the components (A) and (B), the composition of the present invention contains an alkenyl group-containing compound that undergoes an addition reaction with the component (C). May be. As such an alkenyl group-containing compound other than the components (A) and (B), those involved in the formation of a cured product are preferred, and the components (A) and (B) having at least one alkenyl group per molecule Other organopolysiloxanes may be mentioned. The molecular structure may be any of linear, cyclic, branched, three-dimensional network, etc., for example.

((E) component)
-Addition reaction control agent An addition reaction control agent can be mix | blended with this invention composition in order to ensure pot life. The addition reaction control agent is not particularly limited as long as it is a compound having a curing inhibitory effect on the hydrosilylation catalyst of the component (D), and conventionally known ones can also be used. Specific examples thereof include phosphorus-containing compounds such as triphenylphosphine; nitrogen-containing compounds such as tributylamine, tetramethylethylenediamine and benzotriazole; sulfur-containing compounds; 1-ethynylcyclohexanol, 3-methyl-1-butyne-3- Acetylene alcohols such as all, 3,5-dimethyl-1-hexyn-3-ol, 3-methyl-1-penten-3-ol, phenylbutynol; 3-methyl-3-pentene-1-yne And acetylene compounds such as 3,5-dimethyl-1-hexyne-3-yne; compounds containing two or more alkenyl groups; hydroperoxy compounds; and maleic acid derivatives.

The degree of curing inhibition effect 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 to an optimum amount for each of the addition reaction control agents to be used. By adding an optimal amount of addition reaction control agent, the composition has excellent long-term storage stability at room temperature and heat curability.

Furthermore, as necessary, other known antioxidants, pigments, stabilizers, antistatic agents, antifoaming agents, adhesion improvers, thickeners, silica, etc., as long as they do not interfere with the effects of the present invention. An inorganic filler such as can be blended.

[Heavy release composition for release sheet]
The heavy release composition of the present invention preferably has a viscosity at 25 ° C. of 50 to 2,000 mPa · s, particularly 50 to 1,000 mPa · s. If the viscosity is out of this range, problems such as inability to apply when forming a cured film on the substrate and a uniform film may occur.

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

[Method for producing heavy release composition for release sheet]
In the heavy release composition of the present invention, it is desirable from the viewpoint of pot life that the components (A) to (C) and the optional components are mixed in advance and then the component (D) is added immediately before use.

[Coated product (release sheet)]
The release sheet of the present invention is a release sheet having a sheet-like substrate and a cured film of the heavy release composition on one or both surfaces of the substrate surface. The above-mentioned heavy release composition is applied to one or both surfaces of the substrate surface, and a cured film can be formed by heating.

For example, coating the heavy release composition as it is, coating with a comma coater, lip coater, roll coater, die coater, knife coater, blade coater, rod coater, kiss coater, gravure coater, wire bar coater, etc., screen coating, dip coating Using a coating method such as cast coating, 0.01 to 100 g / m ^{2 is} applied on one or both sides of a sheet-like substrate such as paper or film, and then at 50 to 200 ° C. for 1 to 120 seconds. By heating, a cured film can be formed on the substrate. When the release layers are formed on both surfaces of the substrate, it is preferable to perform a cured film forming operation for each surface of the substrate.

In the present invention, the release sheet includes not only those in which the sheet-like base material is paper but also those formed of various known films. Examples of base materials include polyethylene laminated paper, glassine paper, fine paper, kraft paper, clay coated paper, various coated papers, synthetic paper such as YUPO, polyethylene films, polypropylene films such as CPP and OPP, and polyester films such as polyethylene terephthalate films. , Polyamide film, polyimide film, polylactic acid film, polyphenol film, polycarbonate film and the like. It is also possible to use process paper for manufacturing artificial leather, ceramic sheets, double-sided separators and the like as a base material. In order to improve the adhesion between the substrate and the release layer, the substrate surface may be subjected to corona treatment, etching treatment, primer treatment or plasma treatment.

[Peeling sheet]
In the present invention, a release sheet prepared by applying 0.9 to 1.2 g / m ² of the above heavy release composition on a polyethylene laminated paper substrate and then heating at 140 ° C. for 30 seconds is obtained by the FINAT test method. The peel force measured by is from 5 to 20 N / 25 mm. Thereby, it can use as a peeling material with a high heavy peeling effect. Moreover, it is also a feature of the release sheet of the present invention that there is little change in peel force over time. In the present invention, the “heavy release composition” refers to a composition having the above peeling force by the above measuring method.

[Initial peel force measurement method]
After the release sheet obtained by the above curing method is stored at 25 ° C. for 24 hours, the peel force measured by the FINAT test method as described above is defined as the initial peel force. In the present invention, 5 to 15 N / 25 mm is preferable. Details of the measurement method are those described in the examples.

[Method of measuring peel strength over time]
After the release sheet obtained by the above curing method is stored at 50 ° C. for 7 days, the peel force measured by the FINAT test method as described above is defined as the peel force with time. In the present invention, 5 to 15 N / 25 mm is preferable. Details of the measurement method are those described in the examples.

Hereinafter, although a synthesis example, an Example, and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example.

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

Hereinafter, the raw materials used in the examples will be described.
(A) the average molecular _{formula: ViMe 2 SiO (SiMe 2 O} ) 14 organopolysiloxane (B-1) represented by the _{SiMe 3 Me 3 SiO 1/2, ViMe} 2 SiO 1/2, and in SiO _4/2 units Organopolysiloxane having a molar ratio of Me ₃ SiO _1/2 and ViMe ₂ SiO _1/2 to SiO _4/2 of 0.8 and a vinyl group content to the solid content of 0.085 mol / 100 g Resin (solid at 25 ° C)
(B-2-1) Average molecular formula: ViMe ₂ SiO (SiMe ₂ O) ₈ Organopolysiloxane represented by SiMe ₂ Vi (liquid at 25 ° C.)
(B-2-2) Average molecular formula: ViMe ₂ SiO (SiMe ₂ O) ₁₅₀ Organopolysiloxane represented by SiMe ₂ Vi (liquid at 25 ° C.)
(C-1-1) Average molecular formula: Me ₃ SiO (SiHMeO) ₄₆ Methyl hydrogen siloxane represented by SiMe ₃ (C-1-2) Average molecular formula: Me ₃ SiO (SiHMeO) ₁₀₀ SiMe ₃ Methyl hydrogen siloxane (C-1-3) average molecular formula: Me ₃ SiO (SiHMeO) ₄₅ (SiMe ₂ O) ₁₇ Methyl hydrogen siloxane (C-2-1) average molecular formula represented by SiMe ₃ : HMe ₂ SiO Methyl hydrogen siloxane represented by (SiMe ₂ O) ₈ SiMe ₂ H (C-2-2) Average molecular formula: HMe ₂ SiO (SiMe ₂ O) ₆₀ Methyl hydrogen siloxane represented by SiMe ₂ H (D) Platinum catalyst (E) 1-ethynylcyclohexanol obtained in Preparation Example 1 (addition reaction control agent)
(F) 1,3,5,7-tetramethyltetravinyltetracyclosiloxane (H / Vi regulator)

[Example 1]
(1) Average molecular formula: ViMe ₂ SiO (SiMe ₂ O) ₁₄ Linear dimethylpolysiloxane (A) whose one end is blocked with a vinyl group, represented by SiMe ₃ , Me ₃ SiO _1/2 , ViMe ₂ It is composed of SiO _1/2 and SiO _4/2 units, and the molar ratio of Me ₃ SiO _1/2 and ViMe ₂ SiO _1/2 to SiO _4/2 is 0.8. An xylene solution of organopolysiloxane resin (B-1) having an amount of 0.085 mol / 100 g was mixed at a mass ratio of 10:50 in terms of active ingredient. Linear dimethylpolysiloxane (B-2-1) 13 in which both ends represented by an average molecular formula: ViMe ₂ SiO (SiMe ₂ O) ₈ SiMe ₂ Vi are blocked with vinyl groups is added to 60 parts by mass of the liquid. Part by mass, average molecular formula: Me ₃ SiO (SiHMeO) ₄₆ part by mass of methyl hydrogen siloxane (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 is mixed with 8.5 parts by mass of methylhydrogensiloxane (C-2-1) having SiH only at the terminal end, and xylene was added at 150 ° C. under a reduced pressure of 20 mmHg or less. Removal gave a clear liquid (molar ratio of total SiH groups to total alkenyl groups in the composition, ie H / Vi was 1.2).
(2) To 100 parts by mass of the liquid, 0.2 parts by mass of 1-ethynylcyclohexanol (E component) as an addition reaction control agent and 2 parts by mass of the platinum catalyst (D) obtained in Synthesis Example 1 were uniformly added. By mixing, a transparent composition having a viscosity of 890 mPa · s was obtained.

[Examples 2 to 12, Comparative Examples 1 to 8]
Thereafter, the components (A), (B), and (C) were mixed in the same manner as in Example 1, and then xylene in the component (B-1) was removed by distillation under reduced pressure. The other component (F), the component (E) which is an addition reaction control agent, and the platinum catalyst (D) obtained in Synthesis Example 1 were mixed to obtain the heavy release composition shown. The blending amount (unit: parts by mass) is shown in the following table. In the table, (A) component content / (A) component and (B) component total amount is the content of component (A) relative to 100 parts by mass of component (A) and component (B) ( (Parts by mass), (B-2) / (B-1) is (B-2) component content (parts by mass) / (B-1) component content (parts by mass), (C-2) / (C -1) represents (C-2) component content (parts by mass) / (C-1) component content (parts by mass).

The viscosity (absolute viscosity measured with a B-type rotational viscometer at 25 ° C.) of the composition obtained as described above was measured, and a release sheet was prepared by the method described below to evaluate the release force. The obtained results are shown in the table. In the table, “Z” indicates zipping. Peeling force maintenance rate [%] is a value determined from time-dependent peeling force / initial peeling force × 100 [%].

Fig. 1 shows the result of measuring the peel force during zipping, and Fig. 2 shows the result of a normal peel force measurement without zipping. As shown in FIG. 1, when zipping, the peeling force is not stable, and it is difficult to accurately measure the peeling force.

[Method of curing heavy release composition]
After preparing the heavy release composition, the heavy release composition was applied to a polyethylene laminated paper base so as to be 0.9 to 1.2 g / m ² and heated in a hot air drier at 140 ° C. for 30 seconds. This was used as a release sheet for the following measurements.

[Measurement method of initial peel force]
After the release sheet obtained by the above curing method was stored at 25 ° C. for 24 hours, a 25 mm wide acrylic pressure-sensitive adhesive tape Tessa7475 (trade name made by Tesa Tape. Inc.) was applied, and 20 g / cm ^{2 in} a dryer at 70 ° C. A sample was taken out 24 hours after applying the load and used as a sample. After air cooling for about 30 minutes, the sample Tessa7475 tape was peeled off at 0.3 m / min at an angle of 180 ° using a tensile tester (DSC-500 type tester manufactured by Shimadzu Corporation). The required force was measured.

[Method of measuring peel force with time]
After the release sheet obtained by the above curing method was stored at 50 ° C. for 7 days, a laminate of 25 mm wide acrylic adhesive tape Tesa 7475 (trade name, manufactured by Tesa Tape. Inc) was bonded to 20 g in a dryer at 70 ° C. The sample was stored for 24 hours with a load of / m ² . After air cooling for about 30 minutes, the sample TESA-7475 tape is peeled off at 0.3 m / min at an angle of 180 ° using a tensile tester (DSC-500 type tester manufactured by Shimadzu Corporation) and peeled off. The force required for the measurement was measured.

From the above results, the heavy release compositions of the present invention (Examples 1 to 12) have high fluidity at 25 ° C., and the release sheet has a high release force of 5 N / 25 mm or more in the initial stage. Moreover, it has a peel strength of 85% or more with respect to the initial stage even after aging. Further, there is no occurrence of zipping at the time of peeling at the initial stage and after the passage of time. Therefore, the heavy release composition of the present invention is useful as a material for a release sheet for heavy release.

On the other hand, when the amount of the component (A) is increased (Comparative Example 2) and when the component (C-1) is decreased and the component (C-2) is increased (Comparative Examples 7 and 8), the crosslinking density is As a result, the release sheet was lightly peeled. Conversely, when component (A) is not included (Comparative Example 1), when component (B-2) is not included (Comparative Example 3), when component (C-1) is increased and component (C-2) is decreased In (Comparative Examples 5 and 6), the crosslinking density increased too much, and zipping occurred during peeling. In addition, when the component (B-2) was increased as in Comparative Example 4, the viscosity of the composition became too low, resulting in poor coating on the substrate. From the above results, it is considered that the compositions shown in Comparative Examples 1 to 8 are unsuitable for the uses as described above.

Note that the present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

Claims (8)

1. (A) The following general formula (1):
   

   

   (In the formula, R ¹ is an alkenyl group, R ² is an unsubstituted or substituted monovalent hydrocarbon group that does not contain an alkenyl group, and a is a positive number that satisfies 1 ≦ a ≦ 200.)
   One-terminal reactive organopolysiloxane having one alkenyl group at the end represented by the formula: 10 to 35 parts by mass with respect to the total amount of component (A) and component (B) (B) 2):
   R ³ _b SiO _{(4-b) / 2} (2)
   (Wherein R ³ is independently an unsubstituted or substituted monovalent hydrocarbon group, and b is a positive number satisfying 0 ≦ b ≦ 3). Organopolysiloxane having an alkenyl group: 65 to 90 parts by mass of component (B) with respect to 100 parts by mass in total of component (A) and component (B) (C) The following average composition formula (3):
   R ⁴ _c H _d SiO _{(4-cd) / 2} (3)
   (In the formula, R ⁴ is an unsubstituted or substituted monovalent hydrocarbon group which does not contain an alkenyl group independently, and c and d are 0.7 ≦ c ≦ 2.1, 0.001 ≦ d ≦ 1. 0 and a positive number satisfying 0.8 ≦ c + d ≦ 3.0.)
   An organohydrogenpolysiloxane having at least two hydrogen atoms bonded to a silicon atom represented by the formula: in the component (C) with respect to all alkenyl groups in the components (A) and (B) An amount in which hydrogen atoms bonded to silicon atoms are 0.5 to 5.0 times mol,
   (D) platinum group metal catalyst: a heavy release composition for a release sheet containing an effective amount,
   The component (B) has an organopolysiloxane resin (B-1) having a three-dimensional network structure having at least two alkenyl groups in one molecule and being waxy or solid at 25 ° C., and at 25 ° C. It is a combination of a linear or branched organopolysiloxane (B-2) having at least two alkenyl groups at the terminals, which is liquid, and comprises (B-1) and (B-2) The mass ratio (B-2) / (B-1) is 0.1 to 0.5, and
   The component (C) has an organohydrogenpolysiloxane (C-1) having a hydrogen atom bonded to a silicon atom in the side chain, and a hydrogen atom bonded to a silicon atom at the terminal and not in the side chain. Release sheet which is a combination of organohydrogenpolysiloxane (C-2) and has a mass ratio (C-2) / (C-1) of components (C-1) to (C-2) of 1 to 5 Heavy release composition.
2. The component (B-1) has the following average composition formula (4):
   (R ⁶ ₃ SiO _1/2 ) _e (R ⁵ R ⁶ ₂ SiO _1/2 ) _f (R ⁵ R ⁶ SiO) _g (R ⁶ ₂ SiO) _h (R ⁵ SiO _3/2 ) _i (R ⁶ SiO _3/2 ) _j (SiO _4/2 ) _k (4)
   (In the formula, R ⁵ independently represents an alkenyl group, R ⁶ independently represents an unsubstituted or substituted monovalent hydrocarbon group not containing an alkenyl group, provided that at least 80 mol% of all R ⁶ is a methyl group. Yes, e, f, g, h, i, j and k are numbers satisfying e ≧ 0, f ≧ 0, g ≧ 0, h ≧ 0, i ≧ 0, j ≧ 0 and k ≧ 0, respectively. Yes, provided that 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.
   2. The heavy release for release sheet according to claim 1, which is an organopolysiloxane resin having a three-dimensional network structure which is waxy or solid at 25 ° C. and has at least two alkenyl groups in one molecule. Composition.
3. The above (B-2) is the following average composition formula (5):
   (R ⁸ ₃ SiO _1/2 ) _l (R ⁷ R ⁸ ₂ SiO _1/2 ) _m (R ⁸ ₂ SiO) _n (R ⁸ SiO _3/2 ) _p (SiO _4/2 ) _q (5) )
   (Wherein R ⁷ independently represents an alkenyl group, R ⁸ independently represents an unsubstituted or substituted monovalent hydrocarbon group not containing an alkenyl group, provided that at least 80 mol% of all R ⁸ is a methyl group. L, m, n, p and q are numbers satisfying l ≧ 0, m> 0, n ≧ 0, p ≧ 0 and q ≧ 0, respectively, provided that n + p + q> 0, p + q <0. 1 and a number satisfying l + m + n + p + q = 1.)
   The heavy release composition for release sheets according to claim 1 or 2, which is a linear or branched organopolysiloxane having at least two alkenyl groups at the terminals, which is liquid at 25 ° C.
4. The component (C-1) is the following average composition formula (6):
   (R ⁹ ₃ SiO _1/2 ) _r (R ⁹ ₂ HSiO _1/2 ) _s (R ⁹ HSiO) _t (R ⁹ ₂ SiO) _u (HSiO _3/2 ) _v (R ⁹ SiO _3/2 ) _w ( SiO _4/2 ) _x (6)
   (Wherein R ⁹ independently represents an unsubstituted or substituted monovalent hydrocarbon group not containing an alkenyl group, and r, s, t, u, v, w and x are r ≧ 0 and s ≧, respectively. 0, t ≧ 0, u ≧ 0, v ≧ 0, w ≧ 0 and x ≧ 0, provided that t + v> 0 and s + t + u + v + w + x + y = 1.)
   The heavy release composition for a release sheet according to any one of claims 1 to 3, which is an organohydrogenpolysiloxane having a hydrogen atom bonded to a silicon atom in the side chain, represented by:
5. The component (C-2) has the following average composition formula (7):
   (R ¹⁰ ₃ SiO _1/2 ) _α (R ¹⁰ ₂ HSiO _1/2 ) _β (R ¹⁰ ₂ SiO) _γ (R ¹⁰ SiO _3/2 ) _δ (SiO _4/2 ) _ε (7)
   (Wherein R ¹⁰ independently represents an unsubstituted or substituted monovalent hydrocarbon group not containing an alkenyl group, and α, β, γ, δ, and ε are α ≧ 0, β> 0, γ, respectively. ≧ 0, δ ≧ 0, and ε ≧ 0, provided that γ + δ + ε> 0, δ + ε <0.1, and α + β + γ + δ + ε = 1.)
   The heavy release composition for release sheets according to any one of claims 1 to 4, which is an organohydrogenpolysiloxane having a hydrogen atom bonded to a silicon atom at the end and not having a side chain. .
6. The heavy release composition for release sheets according to any one of claims 1 to 5, wherein the viscosity at 25 ° C is 50 to 2,000 mPa · s.
7. A release sheet comprising a sheet-like substrate and a cured film of the heavy release composition for a release sheet according to any one of claims 1 to 6 on one or both surfaces of the substrate surface.
8. The release sheet according to claim 7, wherein a peel force measured by attaching a Tessa7475 tape to the cured film and measuring at 180 ° and a peel rate of 0.3 m / min is 5 to 20 N / 25 mm.

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