JP2003003183A - Solvent type silicone composition for mold release agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a solvent type silicone composition for mold release agent having a curing rate higher than that of the conventional one, providing a cured coating film with a light peel at a high-speed peel, having a slight change in peel force with time of cured coating film, a readily adjustable peel force, being readily handled and even in the case of using a substrate with low heat resistance such as a plastic film as a substrate for a release paper, exhibiting an excellent adhesion to the substrate. SOLUTION: This solvent type silicone composition for mold release agent comprises (A) a branched organopolysiloxane which contains two or more alkenyl groups in one molecule and has a structure represented by the general formula: M<1> a Tb Dc M<2> d , (B) an organohydrogenpolysiloxane containing three or more hydrogen atoms bonded to silicon atoms in one molecule, (C) a catalytic amount of a platinum-based catalyst, (D) an addition reaction inhibitor and (E) an organic solvent.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a solvent-type silicone composition for a release agent, which can be applied to the surface of paper, laminated paper, plastic film and the like to form a non-adhesive cured film.

[0002]

2. Description of the Related Art Conventionally, for the purpose of preventing adhesion or sticking between a substrate such as paper or plastic film and an adhesive substance, a cured film of a silicone composition is formed on the surface of the substrate so that the peelability is improved. Is being given. As a method for forming a cured film of a silicone composition on the surface of a base material, (1) a platinum compound is used as a catalyst to cause an addition reaction between an organopolysiloxane containing an alkenyl group and an organohydrogenpolysiloxane to form a base material. A method of forming a peelable film on the surface, (2) using an organic acid metal salt catalyst such as an organic tin compound, a condensation reaction of an organopolysiloxane containing a hydroxyl group or an alkoxy group with an organohydrogenpolysiloxane, A method of forming a peelable film on the surface of a base material is known.

The peeling characteristics required for these silicone coatings are, in addition to the peeling characteristics at low-speed peeling, in recent years, in order to cope with high-speed rewinding and scrap removal of labels at high speeds, high-speed peeling is light. There is a growing demand for silicone coatings with release properties. A method for providing a silicone film having excellent curability and high-speed peelability and light peeling property is to add-react an alkenyl group-containing organopolysiloxane of the general formula (Formula 1) with an organohydrogenpolysiloxane. A method of forming a peelable film is used. In this case, as an example of the alkenyl group-containing organopolysiloxane, a linear organopolysiloxane represented by the following general formula (Formula 6) can be used.

[Chemical 3] (In the formula, R ¹ is an alkenyl group, and R ² is a substituted or unsubstituted group.
Monovalent organic group, R ³ is a substituted or unsubstituted monovalent saturated organic group, e is 2,000 to 20,000, and f is 2 to 2,
It is 000. )

However, when a straight-chain organopolysiloxane is used, the characteristics of light peeling cannot be obtained at both low speed and high speed peeling. Therefore, in order to improve high speed light peeling and curability, RSiO _3/2 units are used. A composition using an alkenyl group-containing organopolysiloxane having a branched structure is disclosed in JP-A-63-251465 and JP-B-3-01926.
7, JP-A-9-078032, JP-A-11-193.
No. 366 is proposed. However, when an alkenyl group-containing organopolysiloxane having a branched structure proposed in each of these publications is used, a release paper exhibiting light release by high-speed release can be obtained, but a release paper exhibiting light release by low-speed release can be obtained. Hard to get.

In recent years, plastic films have been used as base materials for release paper because of their stable quality, high smoothness, easy thinning, and availability of various varieties. The amount is increasing. When using a plastic film as a base material for release paper, the problems are that the adhesiveness between the base material film and the silicone film is poor, and the low heat resistance that is the original property of the plastic film (the thin film of the plastic film). At present, the tendency is further accelerated) and the curing temperature of the silicone release agent composition cannot be raised because of this tendency. In each of the above publications, it is described that the composition using the alkenyl group-containing organopolysiloxane having a branched structure is excellent in curability, but at present, improvement of curability at a lower temperature is required. Has been.
Regarding the adhesion between the base film and the silicone film,
Japanese Examined Patent Publication No. 3-019267 describes the effect of improving the curability of a composition using an alkenyl group-containing organopolysiloxane having a branched structure. However, in order to obtain good adhesion at a lower curing temperature. , Still not enough. As described above, it gives a cured film that is excellent in curability and that can be easily peeled at high speed, and even when a low heat resistant substrate such as a plastic film is used as the release paper substrate, On the other hand, there is a demand for a solvent-type silicone composition for a release agent, which exhibits excellent adhesion.

[0006]

An object of the present invention is to provide a cured film which is excellent in curability and can be rapidly peeled off at a high speed and has a low heat resistance such as a plastic film as a base material for release paper. Another object of the present invention is to provide a solvent-type silicone composition for a release agent, which exhibits excellent adhesion to a substrate even when a material is used.

[0007]

[Means for Solving the Problems] The following (A), (B),
A solvent type silicone composition for a release agent, comprising (C), (D) and (E). (A) 100 parts by weight of a branched organopolysiloxane having two or more alkenyl groups in one molecule, having a structure represented by the following general formula (1), and having a viscosity at 25 ° C. of 500 Pa · s or more,

[Chemical 4] [In the formula, M ¹ is a general formula (2), T is a general formula (3), D is a general formula (4), M ² is a structural unit represented by a general formula (5), and an oxygen atom in the formula Shall be shared with the adjacent structural units to form a siloxane bond. R ¹ is an alkenyl group, R ² is a substituted or unsubstituted monovalent organic group, and a is 2
Above, b is an integer of 5-100, c is 2,000-20,0
00 is an integer, d is 0 or a positive integer, and a + d = b
It is a number that satisfies +2. ]

[Chemical 5] (B) It has 3 or more hydrogen atoms bonded to silicon atoms in one molecule, and the number of moles of hydrogen atoms bonded to silicon atoms is 1 to 5 times the total number of moles of alkenyl groups in (A). (C) catalytic amount of platinum-based catalyst (D) 0.01 to 10 parts by weight, (E) organic solvent 100 to 10,000 to parts by weight.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below.
To do. In one molecule of the component (A) in the composition of the present invention
Branched organopolysiloxane having two or more alkenyl groups
Xane has a structure represented by the general formula (Formula 1)
Is. Where R¹Is vinyl, allyl, propenyl, etc.
Alkenyl group of R²Is methyl, ethyl, propyl,
Alkyl group such as chill; cyclo such as cyclohexyl group
Alkyl group; Alkenes such as vinyl, allyl, and propenyl
Nyl group; aryl group such as phenyl and tolyl or the like
Some or all of the hydrogen atoms bonded to the carbon atoms of these groups
Substituted with a halogen atom, cyano group, amino group, etc.
Loromethyl group, trifluoropropyl group, cyanoethyl
A substituted or unsubstituted monovalent hydrocarbon group such as a group, and
Is methoxy, ethoxy, propoxy, methoxyethoxy
From alkoxy groups such as Si groups, hydroxyl groups, epoxy groups, etc.
It is a substituted or unsubstituted monovalent organic group of choice. R¹
The vinyl group is industrially preferable, and the branched group of the component (A) is
R contained in Luganopolysiloxane ²At least that
Of 80% by weight of methyl group is industrially and characteristically
Is also preferable.

The branched organopolysiloxane as the component (A) has two or more alkenyl groups in one molecule,
If the number is less than 2, uncrosslinked molecules are likely to remain even after curing, and the curability decreases, which is not preferable. The content of alkenyl groups per 100 g of branched organopolysiloxane is preferably 0.001 mol to 0.1 mol. If it is less than 0.001 mol, curability is deteriorated, and if it exceeds 0.1 mol, pot life is increased. It becomes too short to use. B in the general formula (Formula 1) is a number that determines the branched structure of the branched organopolysiloxane, and is an integer of 5 to 100,
When it is less than 5, branching is small and the effect of reducing the peeling force in high-speed peeling is not sufficient, and when it exceeds 100, industrially stable production becomes difficult. It is preferably 6 to 80. c is 2,000 to 20,000. If it is less than 2,000, the coatability is poor, and if it exceeds 20,000, the workability is poor. It is preferably 5,000 to 10,000.

A and d are the number of siloxane units located at the molecular ends of the branched organopolysiloxane, a is 2 or more, d is 0 or a positive integer, and the number of branches and the number of molecular ends are From the relationship, it is necessary to satisfy a + d = b + 2. The only structural unit that has an alkenyl group is M ¹ , and a is 2 or more because the number of alkenyl groups in one molecule is 2 or more. The alkenyl group is preferentially arranged at the end of the molecular chain. It means that. Even if d = 0, a +
If d = b + 2 can be satisfied, d = 0 is more preferable for achieving good curability. If a + d is smaller than b + 2, the physical properties of the organopolysiloxane will not be stable, and in the worst case, it will be a gelled substance having poor solubility in a solvent, which is not preferable. Although the range of the degree of polymerization of the branched organopolysiloxane is limited by the total value of a, b, c, and d, the indication based on the viscosity is practically useful.
The viscosity of a polymer having a high degree of polymerization is generally represented by the limiting viscosity ηr, but the limiting viscosity ηr of the branched organopolysiloxane is particularly preferably in the range of 1.0 to 3.0.
When r is less than 1.0, coatability is poor, and when it exceeds 3.0, workability is deteriorated.

The method for synthesizing the branched organopolysiloxane as the component (A) is, for example, after hydrolyzing and condensing an alkyltrimethoxysilane with an alkenylsiloxane represented by the following general formula (7) under acidic conditions. It is obtained by polymerizing octamethylcyclotetrasiloxane in the presence of an alkali catalyst. Here, R ¹ and R ² are the same as above.

[Chemical 6]

The organohydrogenpolysiloxane as the component (B) in the present invention is not particularly limited, except that it is necessary to have three or more hydrogen atoms bonded to silicon atoms in one molecule. The molecular structure may be linear, branched or cyclic. Also, the viscosity is 5 mP
It may be in the range of a · s to 1000 mPa · s.

As specific examples of the component (B) in the present invention, the formulas shown in Chemical formula 7 are shown below, but the present invention is not limited thereto.

[Chemical 7] [However, in each of the above formulas, Me is a methyl group, X is a group represented by the following general formula (8), Y is a group represented by the following general formula (9), and g, k, m are 3 to 500, 1, p , S is 1 to 50
0, h, i, j, n, q, r, t, u, v, w are 0 to 500
Is the number of. ]

[Chemical 8]

The blending amount of the organohydrogenpolysiloxane of the component (B) in the present invention is such that the hydrogen atom bonded to the contained silicon atom (hereinafter represented by Si--H).
Is 1 to the total number of moles of alkenyl groups in (A).
The amount is 5 times as large. If the number of moles of Si—H contained in the blending amount of component (B) is less than 1 time the total number of moles of alkenyl groups in (A), the curability is insufficient, and if it exceeds 5 times, However, no remarkable effect is observed, which rather causes the peeling performance to deteriorate over time, and is economically disadvantageous. The amount of the organohydrogenpolysiloxane of the component (B) derived from the above description is 0.1 to 20 parts by weight with respect to 100 parts by weight of the component (A).

The platinum group catalyst as the component (C) in the present invention is used for promoting the addition reaction of the components (A) and (B) to form a cured film. Examples of such platinum group catalysts include platinum black, chloroplatinic acid, chloroplatinic acid-
Examples thereof include an olefin complex, a chloroplatinic acid-alcohol coordination compound, rhodium, and a rhodium-olefin complex. The amount of the component (C) is preferably 5 to 1,000 ppm in terms of platinum or rhodium with respect to the total weight of the components (A) and (B) in order to form a good cured film. It may be appropriately increased or decreased depending on the reactivity of both components A) and (B) or the desired curing rate.

As the addition reaction control agent of the component (D) in the present invention, known compounds can be used. To illustrate this, 3-
Methyl-1-butyn-3-ol, 3,5-dimethyl-
Acetylene alcohols such as 1-hex-3-ol, 3-methyl-1-penten-3-ol, phenylbutynol; 3-methyl-3-penten-1-yne, 3,
Acetylene compounds such as 5-dimethyl-1-hexyne-3-yne; Reaction products of these acetylene compounds with alkoxysilanes or alkoxysiloxanes or hydrogensilanes or hydrogensiloxanes;
Examples thereof include vinyl siloxanes such as tetramethyl vinyl siloxane cyclic compounds; organic nitrogen compounds such as benzotriazole and other organic phosphorus compounds; oxime compounds and organic chromium compounds. The amount of the component (D) blended may be such that the pot life of the composition of the present invention is about 12 hours at room temperature and the stability of the treatment bath is obtained, and the component (A) 10
It is used in an amount of 0.01 to 10 parts by weight, preferably 0.1 to 1 part by weight, based on 0 parts by weight.

The organic solvent of the component (E) in the present invention is
It is blended for the purpose of improving the storage stability of the treatment bath and the coatability of the composition on various substrates, and adjusting the coating amount and the viscosity of the treatment bath. To illustrate this, it is possible to uniformly dissolve the composition of the present invention, such as toluene, xylene, ethyl acetate, acetone, methyl ethyl ketone, and hexane.
In addition, an organic solvent that does not react with the crosslinking agent or the control agent can be used.

The composition of the present invention comprises (A), (B),
It can be easily produced by uniformly mixing the components (C) and (D) in (E). In this mixing, it is preferable that the component (A) is first uniformly dissolved in the component (E) and then the components (B) and (D) are mixed. In addition, in order to secure a sufficient pot life,
The component (C) should be added immediately before the production of release paper and the like, and the other components should be mixed. If necessary, the composition of the present invention may further contain an inorganic filler such as silica or a pigment.

To produce a release paper or the like using the composition of the present invention, the composition of the present invention is directly or after diluted with an appropriate organic solvent as described above, and then a bar coater, a roll coater or a reverse coater. Coating with a coater, a gravure coater, an air knife coater, or a thin film is performed by coating a variety of base materials by a known coating method such as a high-precision offset coater or a multi-stage roll coater. The amount of the composition of the present invention applied to the substrate varies depending on the type of the material of the substrate to be applied, but the amount of solid content is 0.1 to 2.0 g / m 2.
A coating amount in the range of ² is preferable because it has a good balance between peeling performance and cost. In this way, by heating the base material coated with the composition of the present invention at 80 to 130 ° C. for 5 to 30 seconds, a cured film is formed on the surface of the base material, and the desired peeling force and residual adhesive force, etc. It is possible to obtain a release paper having the following characteristics.

[0020]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.

(Preparation of branched organopolysiloxane) 1) Preparation of raw material siloxane a (hereinafter abbreviated as VMT) Tetramethyldivinyl in which R ¹ of the general formula (7) is a vinyl group and R ² is a methyl group. 186 g (1 mol, hereinafter abbreviated as VM2) of disiloxane and 272 g (2 mol) of methyltrimethoxysilane were charged into a flask having an internal volume of 1 liter, and 30 g of IPA (isopropyl alcohol), 70 g of water and 50 g of 35% hydrochloric acid were added dropwise to the funnel. Take 0-5
While maintaining the temperature at 0 ° C., the reaction was carried out by dropping while stirring. After aging at 0-5 ° C for 2 hours, leave still to remove the separated acidic water layer, add 100 g of water, stir for 30 minutes and let stand for 30 minutes to wash the separated water layer. The operation was repeated until the aqueous layer became neutral. Two siloxane layers,
Distillation was carried out under reduced pressure of 000 Pa to remove unreacted substances and solvent to obtain 300 g of polysiloxane having a viscosity of 20 mm ² / s. When the composition of this polysiloxane was confirmed by ²⁹ Si-NMR, R ^{1 in the} general formula (2) was a vinyl group,
Siloxane units R ² siloxane units 1 mol of the general formula (3) in which R ² corresponds to a methyl group is equivalent to a methyl group 1
It was a siloxane consisting of moles.

2) Preparation of raw material siloxane b (hereinafter abbreviated as MT) Instead of the tetramethyldivinyldisiloxane of the raw material siloxane a, R ¹ in the general formula (7) corresponds to a methyl group, and R ² also corresponds to a methyl group. 162 g of hexamethyldisiloxane (1
Mol, hereinafter abbreviated as M2) was prepared in the same manner as the raw material siloxane a except that the viscosity was 25 mm ² / s.
280 g of polysiloxane of When the composition of this polysiloxane was confirmed by ²⁹ Si-NMR, a siloxane unit 1 in which R ^{2 in the} general formula (5) corresponded to a methyl group was obtained.
It was a siloxane consisting of 1 mol of siloxane units and R ^{2 of the} formula (3) corresponding to a methyl group.

3) Preparation of branched organopolysiloxane Octamethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane, VMT, MT, V
M2 and M2 were blended so as to match the desired composition ratio of the branched organopolysiloxane and charged into a flask.
05 mmol of KOH was added, and a polymerization reaction was carried out at 150 ° C. for 5 hours, followed by distillation at 150 ° C. under a reduced pressure of 2000 Pa to remove unreacted substances and volatile components, thereby obtaining a branched organopolysiloxane. . The composition confirmed by ²⁹ Si-NMR for this organopolysiloxane is shown in Table 1, a,
It was a branched organopolysiloxane M ¹ _a T _b D _c M ² _d having a composition ratio shown by b, c and d.

(Measurement Method of Critical Viscosity η _r ) i) Measurement of Absolute Viscosity η Toluene Solution of Organopolysiloxane of Various Concentrations (g
/ Liter), and the absolute viscosity η at 25 ° C. is measured using a rotational viscometer. The absolute viscosity of toluene alone is η ₀ . ii) Conversion to specific viscosity Using the absolute viscosities η and η ₀ obtained above, the specific viscosity is calculated by the following formula. Specific viscosity = η / η ₀ -1 iii) Calculation of limiting viscosity η _r The specific viscosity at each concentration was plotted against the concentration (g / liter), and the limit value obtained by extrapolating the obtained straight line to the concentration of 0 g / liter was calculated. The limiting viscosity is η _r .

(Examples and Comparative Examples) [Preparation of Silicone Composition for Release Paper] In a flask having an internal volume of 1 liter equipped with a stirrer, 30 g of the branched organopolysiloxane prepared above was added as the component (A).
As component (E), 570 g of toluene was charged, and 20 to 20
The mixture was stirred and dissolved at 40 ° C. until it became a uniform solution. Then, as the component (B), methylhydrogenpolysiloxane having both ends of the molecular chain blocked with trimethylsilyl groups, containing 95 mol% of a structural unit represented by MeHSiO _2/2 , and having a viscosity of 25 mPa · s. In an amount 1.5 times the number of moles of the vinyl group contained in the component (A),
1 part of 3-methyl-1-butyn-3-ol as the component (D) and 1 part by weight containing the structural unit represented by MeHSiO _2/2 were added, and mixed with stirring at 20 to 40 ° C. for 1 hour.
Immediately before coating on the substrate, 50 parts by weight of the complex salt of platinum (C) and vinyl siloxane is added to the component (A) in terms of platinum.
ppm was added to complete the preparation of the composition. With respect to this composition, each property in Table 2 was evaluated according to each evaluation method described below, and the results are shown in Table 2.

The evaluation method of each characteristic will be described below. 1) PET was added to the silicone composition 10 minutes after the addition of the curable catalyst.
Using a bar coater on the surface of the film (thickness 40 μm), apply a solid content of 0.5 g / m ² at 80 ° C.
It was heated for a predetermined time in the hot-air circulation type dryer, and the time until a cured film was completely formed was measured. To determine whether it has completely cured, rub the formed cured film with your finger several times,
The time until it becomes cloudy and free from falling is measured, and this time is taken as the curability.

2) Peel force The silicone composition 10 minutes after the addition of the catalyst was applied to the surface of the PET film (thickness 40 μm) using a bar coater.
A solid content of 0.5 g / m ² was applied, and heat treatment was performed for 30 seconds in a hot air circulation dryer at 100 ° C. to completely form a cured film, and an evaluation separator was produced. After leaving this separator at 25 ° C. and 50% RH for one day, a two-component acrylic solvent-based pressure-sensitive adhesive Oliven BPS-5127 (manufactured by Toyo Ink Co., Ltd.) was applied on the surface of the cured film by wet to a thickness of 100 μm. Heat treatment at 100 ° C. for 3 minutes. Next, a PET film (thickness 4
0 μm), and a back-and-forth pressure contact with a 2 kg roller for one reciprocation, followed by aging at 25 ° C. for 20 hours, and then a sample of 50
The sheet was cut into a width of mm, and the force (N) required to pull and peel the laminated paper at a peeling speed of 0.3 m / min and 60 m / min at an angle of 180 degrees was measured using a tensile tester. . The measurement is made by Shimadzu Corporation Autograph D
It was measured using CS-500 type.

3) Polyester tape / Nitto 31B tape (trade name, manufactured by Nitto Denko Corporation) was attached to the surface of the cured film of the evaluation separator prepared in the same manner as in the measurement of the peel strength of the residual adhesion ratio 2), and After aging at 70 ° C. for 20 hours with the load of 20 g / cm ² being applied on the top, the tape was peeled off and attached to a stainless plate. Next, apply 0.3m of this tape to the surface of the stainless steel plate at an angle of 180 degrees.
The force required to peel and peel at a peeling speed of 1 / min A
(N) was measured. On the other hand, as a blank, a polyester tape was attached to the surface of a Teflon (registered trademark) plate, and the force B (N) required to peel the aged tape from the Teflon plate under the same conditions was measured.
It was calculated by the formula of (A / B) × 100. The residual adhesion rate was evaluated on the basis of 95% or more as O, less than 95% as 90% or more as Δ, and less than 90% as X.

4) A separator having a PET film (thickness 40 μm) as a base material prepared by the same method as the peeling force measurement of the adhesiveness 2) and an OPP film (40 μm, corona-treated) as the base material. And a separator manufactured by the same method at 25 ° C. for 5
After being left at 0% RH (relative humidity), the surface of the cured film was rubbed with a finger, and the number of days until the film surface became cloudy and dropped was examined.

5) Separator 25 times the separator made of a PET film (thickness 40 μm) produced by the same method as the peeling force change 2)
After being left at 50 ° C and 50% RH for 1 day, the peeling force is measured by the same method as 2). When the peeling force measured value in 2) is 50% or more, it is ○, and when it is less than 50%, it is ×. And

6) Pot Life The viscosity of the silicone composition solution for release paper prepared in the examples after standing at room temperature for 1 day was examined, and a value of less than 50 mm ² / s was evaluated as ◯, and a value of 50 mm ² / s or more was evaluated as x.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

The solvent-based silicone composition for a release agent of the present invention has a higher reactivity than a side chain alkenyl group by changing the alkenyl group-containing organopolysiloxane used from a linear structure to a branched structure. By increasing the number of terminal alkenyl groups and increasing the degree of polymerization, high-speed curing at low temperatures became possible. By making the cross-linking density distribution of the cured film more uniform, the adhesion to the substrate is improved, and in addition to high-speed curing at low temperatures, it is used for substrates with low heat resistance and difficult to adhere, such as plastic films. Has expanded. Further, the solvent-type silicone composition for a release agent of the present invention gives a cured film with light release by high-speed release, and the change in the release force over time of the cured film is small and stable, so that the release force can be easily adjusted and handled. easy.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masahiko Ogawa             Gunma Prefecture Usui District, Matsuida Town             Shin-Etsu Chemical Co., Ltd. Silicone electronic materials             Inside the technical laboratory F-term (reference) 4H104 CJ07A PA48 QA08 QA14

Claims (2)

[Claims] 1. The following (A), (B), (C), (D),
A solvent type silicone composition for a release agent comprising (E). (A) 100 parts by weight of a branched organopolysiloxane having two or more alkenyl groups in one molecule, having a structure represented by the following general formula (Formula 1), and having a viscosity at 25 ° C. of 500 Pa · s or more. , [Chemical 1] [In the formula, M ¹ is a general formula (2), T is a general formula (3), D is a general formula (4), M ² is a structural unit represented by a general formula (5), and an oxygen atom in the formula Shall be shared with the adjacent structural units to form a siloxane bond. R ¹ is an alkenyl group, R ² is a substituted or unsubstituted monovalent organic group, and a is 2
Above, b is an integer of 5-100, c is 2,000-20,0
00 is an integer, d is 0 or a positive integer, and a + d = b
It is a number that satisfies +2. ] [Chemical 2] (B) An organohydrogenpolysiloxane having 3 or more hydrogen atoms bonded to silicon atoms in one molecule, wherein the number of moles of hydrogen atoms bonded to silicon atoms is the total of the alkenyl groups in (A). A weight part corresponding to an amount of 1 to 5 times the number of moles, (C) a catalytic amount of a platinum-based catalyst (D) an addition reaction control agent 0.01 to 10 parts by weight, (E) an organic solvent 100 to 10 1,000 parts by weight. 2. The solvent-type silicone composition for a release agent according to claim 1, wherein the limiting viscosity ηr of (A) is in the range of 1.0 to 3.0.