JP2009215428A - Release agent composition and release sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a release agent composition which has predetermined releasing force characteristics and in which fluctuation of releasing force due to variation of the hardened state is prevented. <P>SOLUTION: The release agent composition contains: an organopolysiloxane which has alkenyl groups on terminals and side chains of one molecule wherein an alkenyl group content in the one molecule is 1.0-5.0 mass% and an aryl group content therein is less than 0.5 mass%; an organopolysiloxane which has alkenyl groups on respective terminals of one molecule wherein an aryl group content in the one molecule is 0.5-12.0 mass%; and a linear organopolysiloxane which has alkenyl groups only on respective terminals of one molecule or has no alkenyl group and of which the mass average molecular weight is 50,000-500,000. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a release sheet having a predetermined peel force characteristic and having a peel force characteristic that hardly varies depending on a cured state, and a release agent composition used therefor.

  In recent years, solvent-free silicone release agents are being used for the purpose of environmental friendliness and productivity improvement. Since this type of release agent does not use an organic solvent, it has a low environmental impact and can be coated at a higher speed than a solvent type, so that an improvement in productivity can be expected.

  A release sheet using a solventless release agent is used when producing an adhesive sheet such as a general-purpose adhesive label. Such a pressure-sensitive adhesive sheet is applied to a pressure-sensitive adhesive label sheet in which, for example, a plurality of pressure-sensitive adhesive sheets (adhesive labels) cut into a predetermined size are continuously provided on a long release sheet so as to be peelable. This pressure-sensitive adhesive label sheet is punched so that the pressure-sensitive adhesive sheet becomes a predetermined size by a flat die or a die-cut roll so as to surround a predetermined portion from the surface of the long pressure-sensitive adhesive body on the pressure-sensitive adhesive sheet substrate side, for example. After being applied, the adhesive sheet is produced through a process of removing unnecessary parts (peripheral parts of the adhesive label) (so-called scrap raising process). The adhesive label of this adhesive label sheet is affixed to an adherend by a labeling machine or the like. In such applications, if the peel force is too low, label sticking may occur due to lifting or peeling of the adhesive label when applying the residue raising process or adhesive label. If the peel force is too high, Since there is a case where there is a problem of chipping off or the label may not be peeled off from the release sheet when the label is applied, a predetermined peeling force characteristic is required.

  In order to obtain the above-described peeling force characteristics, conventionally, a silicone composition mainly composed of an organopolysiloxane having a relatively high vinyl group content and an organopolysiloxane having a silicon atom-bonded hydrogen atom has been generally used. The However, when the vinyl group content is high, the variation in the peel strength of the resulting release sheet increases due to the difference in the cured state of the silicone composition, for example, when the curing temperature of the silicone composition is high or low. There exists a problem that the peeling force of the peeling sheet produced differs greatly. Therefore, in order to stabilize the peeling force of the release sheet, strict control of the curing temperature is required. However, for example, when the temperature of the outside air varies depending on seasonal factors, it is difficult to control the curing temperature to be constant.

Conventionally, a release agent composition (for example, Patent Documents 1 to 3) containing a linear organopolysiloxane having a phenyl group in the side chain, a low molecular weight organopolysiloxane, and a high molecular weight organopolysiloxane. A release agent composition containing, for example, Patent Document 4 is known. However, these release agent compositions are intended to improve the speed dependency of the peel force, or to improve the coatability and slipperiness, and cannot suppress fluctuations in the peel force due to differences in the silicone cured state. .
Japanese Patent No. 3504692 JP-A-2-187466 JP 2003-192897 A Japanese Patent No. 3891260

  The present invention has been made in view of the above problems, and has a release force characteristic suitable for general adhesive labels, and a release sheet that can suppress a change in peel force caused by a difference in the cured state of silicone, and its It aims at providing the release agent composition used for a release sheet.

The release agent composition according to the present invention includes the following components (A) to (C).
(A) Organopolysiloxane containing the following components (a) and (b): (a) Each molecule has an alkenyl group at each molecular end and side chain, and the alkenyl group content in one molecule is 1.0. Organopolysiloxane having an aryl group content of less than 0.5% by mass and -5.0% by mass (b) An aryl group content in one molecule having an alkenyl group at each molecular end in one molecule Having an alkenyl group only at each molecular end in one molecule of the organopolysiloxane (B) having a molecular weight of 0.5 to 12.0% by mass or having no alkenyl group 50,000 to 500,000 The organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms in one molecule of the linear organopolysiloxane (C)

The component (a) is preferably an organopolysiloxane represented by the following general formula (I).
R ¹ R ² ₂ SiO (R ² ₂ SiO) _m (RR ¹ SiO) _n OSiR ² ₂ R ¹ ... (I)
In the general formula (I), R is the same or different monovalent hydrocarbon group having no aliphatic unsaturated bond. R ¹ is an alkenyl group having 2 to 10 carbon atoms, R ² is R or R ¹ , and m + n is a natural number.

The component (b) is preferably an organopolysiloxane represented by the following general formula (II).
R ¹ _X R _(3-X) SiO (R ₂ SiO) _a (RR ¹ SiO) _b (RR ² SiO) _c OSiR ¹ _y R _(3-y)・ ・ ・ ・ (II)
In the general formula (II), R is the same or different monovalent hydrocarbon group having no aliphatic unsaturated bond, R ¹ is an alkenyl group, and R ² is an aryl group. x, y, a, b, and c represent integers, and 1 ≦ x ≦ 3, 1 ≦ y ≦ 3, a ≧ 1, b ≧ 0, and c ≧ 1.

The component (B) is preferably an organopolysiloxane represented by the following general formula (III).
R ¹ _v R _(3-v) SiO (R ₂ SiO) _d SiR ¹ _w R _(3-w)・ ・ ・ ・ (III)
In the formula (III), R is the same or different monovalent hydrocarbon group having no aliphatic unsaturated bond, and R ¹ is an alkenyl group. D, v, and w represent integers, and 0 ≦ v ≦ 3 and 0 ≦ w ≦ 3.

  The viscosity at 25 ° C. is 100 to 700 mPa · s, and it is preferably a so-called solventless release agent composition that does not contain an organic solvent.

  The release sheet according to the present invention has a release agent layer formed by curing the release agent composition.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to make the peeling force characteristic of a peeling sheet into a desired thing, the fluctuation | variation of the peeling force by the difference in a hardening state can be suppressed.

Hereinafter, the present invention will be described in more detail using embodiments.
The release sheet according to the present invention comprises a release agent layer on one surface of a release sheet substrate, and is used as a member of an adhesive body. This pressure-sensitive adhesive is a laminate in which a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on one surface of a pressure-sensitive adhesive sheet base material is laminated on the release agent layer of the release sheet so that the release agent layer and the pressure-sensitive adhesive layer are in contact with each other. It is.

  The pressure-sensitive adhesive body is applied to a pressure-sensitive adhesive label sheet in which, for example, a plurality of pressure-sensitive adhesive sheets (pressure-sensitive adhesive labels) cut into a predetermined size are continuously provided on a long release sheet. This pressure-sensitive adhesive label sheet is punched so that the pressure-sensitive adhesive sheet has a predetermined size by a flat die or a die-cut roll so as to surround a predetermined portion from the surface of the long pressure-sensitive adhesive body on the pressure-sensitive adhesive sheet substrate side. Is applied, unnecessary parts of the pressure-sensitive adhesive sheet (peripheral parts of the pressure-sensitive adhesive label) are removed.

  The release agent layer is formed by applying a release agent composition on a release sheet substrate and then heating or using a combination of heating and light irradiation such as ultraviolet rays to form a release coating on the release agent composition. The The release agent composition used for the release agent layer contains the following components (A) to (D).

The component (A) is an organopolysiloxane containing the following components (a) and (b).
As the component (a), an organopolysiloxane having an alkenyl group at each molecular end and side chain in one molecule is used. In the component (a), the alkenyl group content in one molecule is 1.0 to 5.0% by mass, preferably 2.0 to 3.5% by mass, and the aryl group content in one molecule. Is less than 0.5% by weight. Specifically, organopolysiloxanes represented by the following general formula (I) are preferably used.
R ¹ R ² ₂ SiO (R ² ₂ SiO) _m (RR ¹ SiO) _n OSiR ² ₂ R ¹ ... (I)

In the general formula (I), R is the same or different monovalent hydrocarbon group having no aliphatic unsaturated bond. R ¹ is an alkenyl group having 2 to 10 carbon atoms, R ² is R or R ¹ , and m + n is a natural number. Examples of the alkenyl group include those having 2 to 10 carbon atoms such as a vinyl group, an allyl group, a propenyl group, and a hexenyl group, and a vinyl group is preferable from the viewpoint of cost. Examples of the monovalent hydrocarbon group for R include those having 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, and specific examples thereof include alkyl groups such as methyl, ethyl and propyl groups. , R may be an aryl group such as a tolyl group or a phenyl group. From the viewpoint of curability and releasability, it is preferable that 80 mol% or more of R is a methyl group, and further, an aryl group may not be contained in the molecule. For example, R in the formula (I) is all alkyl groups. It may be. The mass average molecular weight of the component (a) is, for example, 3,000 to 20,000, preferably 4,000 to 10,000. Moreover, it is preferable that the viscosity in 25 degreeC of (a) component is 50-600 mPa * s, and it is more preferable that it is 100-500 mPa * s. Thereby, the applicability | paintability to the peeling sheet base material of a releasing agent composition can be made more excellent.

As the component (b), an organopolysiloxane having an alkenyl group at each molecular end in one molecule is used. In the component (b), the aryl group content in one molecule is 0.5 to 12.0% by mass, preferably 3.0 to 8.0% by mass. As the component (b), specifically, an organopolysiloxane represented by the following general formula (I) is preferably used.
R ¹ _X R _(3-X) SiO (R ₂ SiO) _a (RR ¹ SiO) _b (RR ² SiO) _c OSiR ¹ _y R _(3-y)・ ・ ・ ・ (II)

In the formula (II), R is the same or different monovalent hydrocarbon having no aliphatic unsaturated bond, R ¹ is an alkenyl group, and R ² is an aryl group. x, y, a, b, and c represent integers, and 1 ≦ x ≦ 3 and 1 ≦ y ≦ 3. Further, a> b and a> c, and a ≧ 1, b ≧ 0, and c ≧ 1, and the component (b) may not have an alkenyl group in the side chain.

In the general formula (II), R includes a monovalent hydrocarbon group having 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, and specifically includes alkyl groups such as a methyl group, an ethyl group, and a propyl group. It is done. Moreover, it is preferable that 80 mol% or more of R is a methyl group from a viewpoint of sclerosis | hardenability and peelability. Examples of the alkenyl group for R ¹ include those having 2 to 10 carbon atoms such as a vinyl group, an allyl group, a propenyl group, and a hexenyl group, and a vinyl group is preferable from the viewpoint of cost. Examples of the aryl group for R ² include a phenyl group and a tolyl group, and a phenyl group is preferable from the viewpoint of cost. The mass average molecular weight of (b) component is 3,000-20,000, for example, Preferably it is 4,000-10,000. Moreover, it is preferable that the viscosity in 25 degreeC of (b) component is 50-600 mPa * s, and it is more preferable that it is 100-500 mPa * s. Thereby, the applicability | paintability to the peeling sheet base material of a releasing agent composition can be made more excellent.

  In the component (A), the blending ratio (mass ratio) of the component (a) and the component (b) is preferably (a) :( b) = 90: 10 to 10:90, and (a) :( b) = 90: 10 to 40:60 is more preferable. When the amount of the component (a) is small, the peel strength of the resulting release sheet cannot be sufficiently increased, and when the amount of the component (b) is small, the peel strength of the release sheet obtained due to the difference in the cured state. Therefore, the ratio of the component (a) to the component (b) is preferably in the above range.

As the component (B), a linear organopolysiloxane having a mass average molecular weight of 50,000 to 500,000 having an alkenyl group only at each molecular terminal or no alkenyl group is used. Since component (B) does not have an aliphatic unsaturated bond such as an alkenyl group in the side chain, only the molecular end is subjected to an addition reaction by the crosslinking agent described later, or both the molecular end and the side chain are added. no response. Specifically, the component (B) is preferably an organopolysiloxane represented by the following general formula (III).
R ¹ _v R _(3-v) SiO (R ₂ SiO) _d SiR ¹ _w R _(3-w)・ ・ ・ ・ (III)

In the formula (III), R is the same or different monovalent hydrocarbon group having no aliphatic unsaturated bond, and R ¹ is an alkenyl group. d, v, and w represent integers, and 0 ≦ v ≦ 3 and 0 ≦ w ≦ 3. Preferably, 1 ≦ v ≦ 3 and 1 ≦ w ≦ 3, and it is better to have an alkenyl group at the molecular end. (B) It is preferable that the mass mean molecular weights of a component are 100,000-500,000, More preferably, it is 200,000-500,000. And it is better to make the mass average molecular weight of (B) component larger than the mass average molecular weight of each of (a) component and (b) component. In the release agent composition, the component (B) is preferably contained in an amount of 1 to 10 parts by mass with respect to 100 parts by mass of the component (A). If the component (B) is less than 1 part by mass, fluctuations in the peeling force due to differences in the cured state cannot be sufficiently suppressed, and if more than 10 parts by mass is added, the viscosity of the release agent composition increases and coating is performed. Sexuality decreases.

In the general formula (III), R has 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, and examples thereof include alkyl groups such as a methyl group, an ethyl group, and a propyl group. A methyl group is preferred. Examples of the alkenyl group for R ¹ include those having 2 to 10 carbon atoms such as a vinyl group, an allyl group, a propenyl group, and a hexenyl group, and a vinyl group is preferable from the viewpoint of cost.

  As the component (C), an organohydrogenpolysiloxane crosslinking agent having at least two silicon-bonded hydrogen atoms (SiH) in one molecule is used. Specifically, dimethylhydrogensiloxy group end-capped dimethylsiloxane-methylhydrogensiloxane copolymer, trimethylsiloxy group end-capped dimethylsiloxane-methylhydrogensiloxane copolymer, trimethylsiloxy group end-capped methylhydrogenpolysiloxane, Examples thereof include poly (hydrogensilsesquioxane), and these may be used alone or in combination. In this embodiment, a cured film is formed by an addition reaction between SiH of these crosslinking agents and an alkenyl group in the release agent composition.

In the stripper composition, the component (C) is preferably added so that the number of silicon-bonded hydrogen atoms is 1.0 to 5.0 (molar ratio) with respect to the number of alkenyl groups, It is more preferable to add so that it may become 1.2-3.0 (molar ratio). This molar ratio is determined from the peak area of the spectrum obtained by analyzing the release agent composition by ¹ H-NMR. When the molar ratio is less than 1.0, the curability of the composition is lowered. When the molar ratio is more than 5.0, the release sheet has a heavy peeling force, and the peeling performance may be deteriorated.

  The component (D) is a platinum group metal catalyst, and a catalytic amount is added to the release agent composition. Examples of platinum compounds used in platinum group metal catalysts include particulate platinum, particulate platinum adsorbed on a carbon powder support, chloroplatinic acid, alcohol-modified chloroplatinic acid, olefin complexes of chloroplatinic acid, palladium And rhodium catalyst. The platinum group metal catalyst is added in an amount of about 1 to 1000 mass ppm as a platinum metal with respect to the total amount of the addition reaction type organopolysiloxane and the crosslinking agent.

  In addition to the components (A) to (D) described above, additives such as reaction inhibitors, adhesion improvers, viscosity modifiers such as liquid α-olefin components may be added to the release agent composition as desired. good. The reaction inhibitor is added for the purpose of suppressing the activity of the catalyst and imparting storage stability at room temperature, and acetylene compounds, oxime compounds, organic nitrogen compounds, organic phosphorus compounds, organic chlorine compounds, and the like are used. Moreover, when light irradiation, such as ultraviolet irradiation, is performed in addition to heating in the curing step after the release agent coating, a photoinitiator may be added to the release agent composition.

  The release agent composition according to this embodiment is a solventless release agent composition, does not contain a solvent, and preferably has a viscosity at 25 ° C. of 100 to 700 mPa · s. By not containing a solvent, an environmentally friendly release agent composition can be provided. Moreover, the applicability | paintability of a release agent composition can be made favorable by adjusting a viscosity to the said range.

The release sheet substrate and the pressure-sensitive adhesive sheet substrate can be appropriately selected and used from known substrates known as release sheets or base materials for pressure-sensitive adhesive sheets. For example, fine paper, glassine paper, coated paper Paper such as cast coated paper and dust-free paper, laminated paper obtained by laminating a thermoplastic resin such as polyethylene on these paper base materials, resin films formed from thermoplastic resin, paper, metal foil, and composites thereof Can be used. The basis weight (mass per unit area) of the release sheet substrate and the pressure-sensitive adhesive sheet substrate is appropriately selected according to the purpose of use, but is usually 20 to 500 g / m ² , preferably 50 to 300 g / m. ² range.

As the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer, a known pressure-sensitive adhesive can be used without particular limitation, and for example, an acrylic pressure-sensitive adhesive is used. The pressure-sensitive adhesive body is formed, for example, by applying a pressure-sensitive adhesive on a release agent layer to form a pressure-sensitive adhesive layer, and further sticking a pressure-sensitive adhesive sheet substrate on the pressure-sensitive adhesive layer. The pressure-sensitive adhesive body may be formed by bonding the pressure-sensitive adhesive sheet and the release sheet after the pressure-sensitive adhesive layer is formed on the pressure-sensitive adhesive sheet substrate. The release agent composition and the pressure-sensitive adhesive are applied by existing methods such as a gravure coating method, a bar coating method, a spray coating method, a spin coating method, a knife coating method, a roll coating method, and a die coating method. The basis weight of the adhesive layer is not particularly limited, is preferably from 5 to 100 g / ^{m 2,} and more preferably 10 to 60 g / ^{m 2.} The basis weight of the release agent layer is not particularly limited, is preferably 0.05-5 g / ^{m 2,} and more preferably 0.1 to 3.0 g / ^{m 2.}

  According to the configuration of the release agent composition, in this embodiment, the release force of the release sheet with respect to the pressure-sensitive adhesive sheet can be set to a value suitable for a general-purpose pressure-sensitive adhesive label, and preferably 200 to 1000 mN / 50 mm. When the release sheet has a release force of less than 200 mN / 50 mm, the pressure-sensitive adhesive sheet may float from the release sheet or peel off unexpectedly. Moreover, when peeling force exceeds 1000 mN / 50mm, it will become difficult to peel an adhesive sheet from a peeling sheet. The peeling force is more preferably 400 to 600 mN / 50 mm in order to further improve the peeling performance of the label.

  In the present embodiment, the configuration of the release agent composition prevents the release force of the release sheet from changing due to the difference in the cured state of the release agent layer. The mechanism is guessed as follows. In the present embodiment, as the organopolysiloxane component, a component (A) having a relatively small molecular weight and a component (B) having a relatively large molecular weight are used. The component (A) having a small molecular weight tends to be cured quickly and easily form a cured film in the vicinity of the release sheet substrate. Thus, the component (B) is in the vicinity of the surface layer of the release agent layer, that is, the adhesive layer. A relatively large amount of segregation occurs near the interface. In particular, in the present embodiment, since the component (A) includes the component (b) having a high aryl group content, these are different from each other due to the difference in molecular structure and polarity between the component (A) and the component (B). It is difficult to dissolve, and it is assumed that the component (B) is easily segregated by the surface layer. The component (B) segregated on the surface layer of the release agent layer has a low alkenyl group content and hardly undergoes an addition reaction at the time of cured film formation, so the film formation state hardly changes due to differences in the curing conditions such as the curing temperature, Therefore, it is guessed that the fluctuation | variation of peeling force is suppressed. In addition, the component (a) having a high alkenyl group content has an effect of sufficiently increasing the peel strength of the release agent layer and making the peel strength characteristic of the release sheet suitable.

In addition, in this specification, a mass average molecular weight means what measured each organopolysiloxane by gel permeation chromatography (GPC), and calculated | required as a polystyrene conversion value. The measurement conditions are as follows.
Measuring device: Shodex GPC SYSTEM-21H (trade name, Showa Denko)
Column: Waters, two styragel (R) HR5E are used Measurement solvent: Chloroform Measurement temperature: 40 ° C
Flow rate: 1.0 ml / min Sample concentration: 1.0%

  Further, in this specification, the viscosity is measured at 25 ° C. according to JIS K7117-1 4.1 (Brookfield rotary viscometer).

¹ H-NMR is analyzed under the following conditions.
Measuring equipment: AVENCE500 (trade name, manufactured by BRUKER BIOSPIN), 500 MHz
Measuring solvent: deuterated chloroform Measuring temperature: 23 ° C

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

[Example 1]
(a) 75.1 parts by weight of a dimethylvinylsilyl group-blocked dimethylsiloxane-methylvinylsiloxane copolymer (hereinafter referred to as polysiloxane a1) having a weight average molecular weight of 7,000 as component (a) and component (b) 12.3 parts by weight of a dimethylvinylsilyl group-blocked dimethylsiloxane-methylphenylsiloxane copolymer (hereinafter referred to as polysiloxane b1) having a weight average molecular weight of 5,000, and both ends dimethylvinylsilyl having a weight average molecular weight of 400,000 It is 3.0 parts by mass of the blocked dimethylpolysiloxane (component (B)), 9.2 parts by mass of the trimethylsilyl group blocked methylhydrogen polysiloxane (component (C)) as a crosslinking agent, and a reaction inhibitor. 0.4 part by mass of 1-ethynyl-cyclohexanol (boiling point 180 ° C.) and platinum group metal catalyst (P t complex) (component (D)) 2.0 parts by mass was added and mixed to obtain a release agent composition. The vinyl group content, phenyl group content, and viscosity at 25 ° C. of polysiloxanes a1, b1 and (B) were as shown in Table 1. In the obtained release agent composition, the viscosity at 25 ° C. was 350 mPa · s. Moreover, the molar ratio (H / Vi molar ratio) of silicon atom-bonded hydrogen atoms to vinyl groups in the release agent composition was 1.6.

Next, the release agent composition is uniformly applied to glassine paper having a basis weight of 80 g / m ² as a release sheet substrate so that the coating amount (basis weight) after drying is 1.0 g / m ^2. Then, the release agent composition is cured by heat treatment under three conditions (A: 150 ° C. for 30 seconds, B: 160 ° C. for 30 seconds, C: 140 ° C. for 30 seconds), and peeled off on one surface of the release sheet substrate Three types of release sheets on which the agent layer was formed were obtained. On each release agent layer of each of these three types of release sheets, an acrylic ester copolymer (monomer composition: acrylic acid-2-ethylhexyl 49 mass%, butyl acrylate 50 mass%, acrylic acid 1 mass%) An acrylic emulsion-type pressure-sensitive adhesive (solid content: 60% by mass) was applied so that the coating amount after drying was 30 g / m ^2, and then heat-treated at 100 ° C. for 2 minutes to form a pressure-sensitive adhesive layer. . On the pressure-sensitive adhesive layer, a high-quality paper having a basis weight of 64 g / m ² which is a pressure-sensitive adhesive sheet base material (manufactured by Nippon Paper Industries Co., Ltd., trade name “NPI foam”) was bonded to obtain three types of pressure-sensitive adhesive bodies.

[Example 2]
The same procedure as in Example 1 was performed except that the blending ratio of the release agent composition was changed as shown in Table 2. In the obtained release agent composition, the viscosity at 25 ° C. was 340 mPa · s.

[Example 3]
The same procedure as in Example 1 was performed except that the blending ratio of the release agent composition was changed as shown in Table 2. In the obtained release agent composition, the viscosity at 25 ° C. was 420 mPa · s.

[Comparative Example 1]
In place of polysiloxane a1, a dimethylvinylsilyl group-blocked dimethylsiloxane-methylphenylsiloxane copolymer (hereinafter referred to as polysiloxane b2) having a mass average molecular weight of 12,000 is blended in the release agent composition, and the blending ratio Was carried out in the same manner as in Example 1 except that as shown in Table 2. The polysiloxane b2 had a vinyl group content, a phenyl group content, and a viscosity at 25 ° C. as shown in Table 1. In the obtained release agent composition, the viscosity at 25 ° C. was 640 mPa · s.

[Comparative Example 2]
In place of polysiloxane b1, a dimethylvinylsilyl group-blocked dimethylsiloxane-methylvinylsiloxane copolymer (hereinafter, referred to as polysiloxane a2) having a weight average molecular weight of 7,800 is blended in the release agent composition and the blending ratio. Was carried out in the same manner as in Example 1 except that as shown in Table 2. The polysiloxane a2 had a vinyl group content, a phenyl group content, and a viscosity at 25 ° C. as shown in Table 1. In the obtained release agent composition, the viscosity at 25 ° C. was 270 mPa · s.

[Comparative Example 3]
(B) It implemented like Example 1 except having mix | blended the component with the release agent composition and having shown a compounding ratio as Table 2. In the obtained release agent composition, the viscosity at 25 ° C. was 370 mPa · s.

The release sheets of each example and comparative example were evaluated by the following methods.
(1) Evaluation of coatability In each of Examples and Comparative Examples, the coatability when a release agent composition was applied to a release sheet substrate was evaluated. The case where the coating property was good was evaluated as “◯”, and the case where the coating property was bad was evaluated as “x”.

(2) Peeling force The pressure-sensitive adhesive bodies obtained in each Example and Comparative Example were left to stand for 1 day under conditions of a temperature of 25 ° C. and a humidity of 50%, and then cut into a width of 50 mm and a length of 150 mm to measure the peeling force. It was. Peeling force is measured using a universal tensile testing machine (trade name “TENSILON UTM-4-100” manufactured by Orientec Co., Ltd.). The peeling sheet is fixed and the pressure sensitive adhesive sheet is used in an environment where the temperature is 23 ° C. and the humidity is 50%. Was peeled in the 180 ° direction at a peeling speed of 0.3 m / min to measure the peeling force of the release sheet on the adhesive sheet.

  When the peeling condition when the curing condition of the release agent composition was 150 ° C. for 30 seconds (condition A) was 200 to 1000 mN / 50 mm, the release sheet was evaluated as “◯” because the release sheet had good peeling force characteristics. On the other hand, if the peel force is outside the above range, the peel force characteristic is not suitable for general adhesive label use, and “x” is given.

(3) Peel stability test The peel force when the curing condition of the release agent composition is 160 ° C. for 30 seconds (B condition) is B, and the peel force when the cure condition is 140 ° C. for 30 seconds (C condition). As C, the peel force stability rate (C / B) was calculated. If the peeling force stability ratio was 1.0 to 1.3, it was judged as “◯” because the peeling stability was good. If the peel force stability factor was less than 1.0 or greater than 1.3, the peel force was unstable, and “x” was assumed to be unusable.

  As is clear from the above evaluation results, polysiloxane having a high alkenyl group content in one molecule (component (a)) and polysiloxane having a high phenyl group content in one molecule (component (b)) are included. In addition, in Examples 1 to 3 which are release agent compositions containing linear organopolysiloxane (component (B)), it is possible to suppress fluctuations in peel force due to differences in the cured state and to achieve desired peel force characteristics. Could get. On the other hand, in Comparative Example 2 that does not include the component (b) and Comparative Example 3 that does not include the component (B), the variation in the peeling force increases due to the difference in the cured state, and the peeling stability cannot be improved. It was. On the other hand, in Comparative Example 1 containing no component (a), the peel strength was too low, and the desired peel strength characteristics could not be obtained.

Claims (6)

A release agent composition comprising the following components (A) to (C):
(A) Organopolysiloxane containing the following components (a) and (b): (a) Each molecule has an alkenyl group at each molecular end and side chain, and the alkenyl group content in one molecule is 1.0. Organopolysiloxane having an aryl group content of less than 0.5% by mass and -5.0% by mass (b) An aryl group content in one molecule having an alkenyl group at each molecular end in one molecule Having an alkenyl group only at each molecular end in one molecule of the organopolysiloxane (B) having a molecular weight of 0.5 to 12.0% by mass or having no alkenyl group 50,000 to 500,000 The organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms in one molecule of the linear organopolysiloxane (C) The release agent composition according to claim 1, wherein the component (a) is an organopolysiloxane represented by the following general formula (I).
R ¹ R ² ₂ SiO (R ² ₂ SiO) _m (RR ¹ SiO) _n OSiR ² ₂ R ¹ ... (I)
In the general formula (I), R is the same or different monovalent hydrocarbon group having no aliphatic unsaturated bond. R ¹ is an alkenyl group having 2 to 10 carbon atoms, R ² is R or R ¹ , and m + n is a natural number. The stripping composition according to claim 1, wherein the component (b) is an organopolysiloxane represented by the following general formula (II).
R ¹ _X R _(3-X) SiO (R ₂ SiO) _a (RR ¹ SiO) _b (RR ² SiO) _c OSiR ¹ _y R _(3-y)・ ・ ・ ・ (II)
In the general formula (II), R is the same or different monovalent hydrocarbon group having no aliphatic unsaturated bond, R ¹ is an alkenyl group, and R ² is an aryl group. x, y, a, b, and c represent integers, and 1 ≦ x ≦ 3, 1 ≦ y ≦ 3, a ≧ 1, b ≧ 0, and c ≧ 1. The release agent composition according to claim 1, wherein the component (B) is an organopolysiloxane represented by the following general formula (III).
R ¹ _v R _(3-v) SiO (R ₂ SiO) _d SiR ¹ _w R _(3-w)・ ・ ・ ・ (III)
In the formula (III), R is the same or different monovalent hydrocarbon group having no aliphatic unsaturated bond, and R ¹ is an alkenyl group. D, v, and w represent integers, and 0 ≦ v ≦ 3 and 0 ≦ w ≦ 3.   The release agent composition according to claim 1, wherein the release agent composition has a viscosity at 25 ° C of 100 to 700 mPa · s and does not contain an organic solvent.   A release sheet comprising a release agent layer formed by curing the release agent composition according to any one of claims 1 to 5.