JP2011098994A - Composition for releasing agent, release sheet and pressure-sensitive adhesive sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-silicone composition for a releasing agent used for a release sheet having excellent light releasing property, a release sheet which suppresses increase of its light releasing power with time, and a pressure-sensitive adhesive sheet having low outgassing property and useful particularly as a pressure-sensitive adhesive sheet for sticking to electronic parts. <P>SOLUTION: The composition for a releasing agent is obtained by adding 2-50 pts.mass of a diene polymer compound having a weight average molecular weight of 1,000-100,000 to 100 pts.mass of a diene polymer compound having a weight average molecular weight of 300,000-1,200,000. The release sheet has, on at least one surface of a release sheet base material, a releasing agent layer formed from the composition for a releasing agent through active energy ray irradiation. The pressure-sensitive adhesive sheet is obtained by laying the releasing agent layer of the release sheet on a pressure-sensitive adhesive layer formed on at least one surface of a pressure-sensitive adhesive sheet base material. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a release agent composition and a release sheet, and particularly to a pressure-sensitive adhesive sheet useful for attaching electronic parts.

Electronic members such as relays, various switches, connectors, motors, and hard disks are widely used in various products. For such electronic members, a single-sided adhesive sheet or a double-sided adhesive sheet is used for the purpose of temporarily fixing at the time of assembly, fixing of parts, displaying the contents of parts, and the like. Such a pressure-sensitive adhesive sheet is usually composed of a pressure-sensitive adhesive layer alone or a base material and a pressure-sensitive adhesive layer. Before being attached to an electronic member, a release sheet is attached to the surface of the pressure-sensitive adhesive layer. Yes.
A release agent layer is provided on the surface of the release sheet (contact surface with the pressure-sensitive adhesive layer) for the purpose of improving peelability. Conventionally, a silicone-based compound has been used as a constituent material of the release agent layer (Patent Documents 1 to 3).
However, it is known that when such a release sheet is attached to an adhesive sheet, a silicone compound such as a low molecular weight silicone resin, siloxane, or silicone oil in the release sheet moves to the adhesive layer of the adhesive sheet. For this reason, when the adhesive sheet affixed to such a peeling sheet is affixed to the said electronic member, the silicone compound which transferred to this adhesive layer gradually vaporizes thereafter. It is said that the vaporized silicone compound is deposited on the surface of the electrical contact portion or the like by, for example, an arc generated in the vicinity of the electrical contact portion of the electronic member to form a small amount of a silicon oxide compound layer. As described above, when the silicon oxide compound is deposited on the surface of the electrical contact portion, it may cause a conduction failure. In particular, when adhered to a hard disk device, the silicone compound transferred to this adhesive layer gradually vaporizes and deposits on the magnetic head, disk surface, etc., and this small amount of silicon oxide compound is deposited on the hard disk. And writing may be adversely affected. In order to solve such a problem, an attempt has been made to develop a release sheet made of a polyolefin-based film that has not been subjected to silicone treatment (see, for example, Patent Document 4).

However, in the pressure-sensitive adhesive sheet in which the release sheet made of the polyolefin film is adhered to the surface of the pressure-sensitive adhesive layer, the pressure-sensitive adhesive is applied and dried on the release sheet because the release sheet has no heat resistance. However, under high temperature conditions (for example, 110 ° C. or more), the release sheet may be damaged due to thermal shrinkage or wrinkles, or the peel strength of the obtained pressure-sensitive adhesive sheet may not be stable, and a part of the pressure-sensitive adhesive layer may be torn. There was a problem that the adhesive residue of the so-called pressure-sensitive adhesive layer adhered to the side of the release sheet peeled off.
In addition, the inside of an electronic member such as a hard disk may become a high temperature atmosphere during use. If gas is generated from the adhesive layer adhered to the electronic member in this high temperature atmosphere, the electronic member may be corroded or malfunctioned. Such as bringing about an unfavorable situation. In order to suppress the generation of such gas, it is necessary to evaporate low-boiling substances such as solvents and unreacted monomers by increasing the drying temperature when forming the pressure-sensitive adhesive layer. In such a release sheet, the above heat resistance problem occurs.
Therefore, it has been proposed to use a diene polymer compound such as polybutadiene as a non-silicone film, not a polyolefin film, and capable of reducing the peeling force (for example, Patent Document 5, 6).
It has been found that the peeling force can be further reduced by further devising these diene polymer compounds.

JP-A-2005-47175 JP 2005-317613 A JP 2007-217553 A Japanese Patent No. 3886225 Japanese Patent Laid-Open No. 2005-199586 JP 2005-205813 A

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a release agent composition capable of forming a release agent layer excellent in light release performance, a release sheet using the same, and In particular, it is an object of the present invention to provide a pressure-sensitive adhesive sheet that does not adversely affect an electronic member or the like, has a small amount of outgas generation, and suppresses an increase in adhesive strength with time after pasting.

In order to achieve the above object, the present inventors have intensively studied, and as a result, achieved the above object by using a release agent composition comprising two kinds of diene polymer compounds having different molecular weights blended in a predetermined ratio. The present invention has been completed.
That is, the present invention adds (2) 2 to 50 parts by weight of a diene polymer compound having a weight average molecular weight of 1,000 to 100,000 to 100 parts by weight of a diene polymer compound having a weight average molecular weight of 300,000 to 1,200,000. A composition for a release agent,
(2) The composition for a release agent according to the above (1), wherein both diene polymer compounds are polybutadiene or polyisoprene,
(3) The release agent composition according to (1) above, wherein both of the diene polymer compounds are 1,4-polybutadiene.
(4) A release agent formed by applying and drying the release agent composition according to any one of (1) to (3) above on at least one surface of a release sheet base material and irradiating with active energy rays. Release sheet having a layer,
(5) The release sheet according to (4), wherein the release agent layer contains an antioxidant,
(6) The release sheet according to (4) or (5) above, which has an undercoat layer between the release sheet substrate and the release agent layer,
(7) The release sheet according to (6), wherein the undercoat layer is an elastic body made of polyurethane,
(8) The normal peeling force for the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive obtained by crosslinking the carboxyl group-free acrylic copolymer with a crosslinking agent is from 30 to 500 mN / 20 mm. A release sheet according to any one of the above,
(9) A pressure-sensitive adhesive sheet obtained by laminating a surface of the release agent layer of the release sheet according to any one of (4) to (8) above and a pressure-sensitive adhesive layer formed on at least one surface of the pressure-sensitive adhesive sheet substrate ,
(10) The pressure-sensitive adhesive sheet according to (9), wherein the pressure-sensitive adhesive layer is a layer obtained by crosslinking a carboxyl group-free acrylic copolymer with a crosslinking agent,
(11) The pressure-sensitive adhesive sheet according to (9) or (10), wherein the amount of gas generated when the pressure-sensitive adhesive layer is heated at 120 ° C. for 30 minutes is 1.0 μg / cm ² or less in terms of n-decane. ,
(12) The pressure-sensitive adhesive sheet according to any one of the above (9) to (11), which is a pressure-sensitive adhesive sheet for an electronic member.

  According to the present invention, a non-silicone-based release agent composition, a release sheet having a release agent layer formed from the same composition is provided, and since there is less outgassing, relays, various switches, connectors, Provided is an adhesive sheet having a release sheet that is less likely to adversely affect electronic members such as motors and hard disks and that is excellent in light release performance.

As shown in a comparative example described later, a diene polymer compound having a relatively low molecular weight (hereinafter sometimes referred to as “LPD”) is cured by active energy ray irradiation and peeled off. When the agent layer is formed, both the normal peel force and the heat accelerated peel force (both peel forces will be described in detail later) are abnormally high. A small amount of such LPD is added to a relatively high molecular weight diene polymer compound (hereinafter sometimes referred to as “PD”) and cured by irradiation with active energy rays to form a release agent layer. Surprisingly, it was found that the peel force can be reduced as compared with the case where PD is used alone.
This is because when a small amount of LPD is added than when PD is used alone, the surface elasticity decreases due to an increase in the distance between cross-linking points, and the peeling force decreases. -Since LPD is involved in cross-linking between PD, the cross-linking form is PD-LPD-PD, and it is estimated that the distance between cross-linking points increases by the amount of LPD, the elastic modulus decreases, and the peel force decreases. The The present invention is based on such knowledge.

First, the composition for release agent will be described.
The composition for a release agent of the present invention comprises 2 to 50 parts by mass of a diene polymer compound having an Mw of 1,000 to 100,000 with respect to 100 parts by mass of a diene polymer compound having a weight average molecular weight (hereinafter referred to as Mw) of 300,000 to 1,200,000. It is an added composition. The Mw of PD is preferably 400,000 to 1,000,000, and the Mw of LPD is preferably 5,000 to 60,000.
By setting the Mw of PD to 300,000 or more, curing by active energy ray irradiation performed to form a release agent from the composition is sufficiently performed. By setting it to 1,200,000 or less, solubility in a solvent is ensured, and a release agent solution suitable for coating can be prepared.
By setting the Mw of LPD to 1000 or more, it is possible to suppress the transfer of the uncured product to the pressure-sensitive adhesive and decrease the pressure-sensitive adhesive performance due to sufficient curing by irradiation with active energy rays. By setting the weight average molecular weight of LPD to 100,000 or less, the difference from the lower limit value of 300,000 of PD becomes small, and it is possible to prevent the effect of light peeling by addition from being obtained.
As PD and LPD, diene homopolymers such as polybutadiene and polyisoprene, and diene copolymers such as styrene-butadiene copolymer, styrene-isoprene copolymer, ethylene-propylene-diene copolymer (EPDM), etc. In particular, polybutadiene and polyisoprene are preferably used.
Among them, from the viewpoint of reducing the peeling force, polybutadiene is preferable, and more specifically 1,4-polybutadiene is preferable. 1,4-polybutadiene may be either a cis structure or a trans structure, and may contain any cis structure. The quantity can be used.
In addition, Mw in this invention is Mw of standard polystyrene conversion measured by the gel permeation chromatography (GPC) method.

The addition amount of LPD is 2 to 50 parts by mass, preferably 3 to 30 parts by mass with respect to 100 parts by mass of PD.
By setting the addition amount of LPD to 2 parts by mass or more, an increase in the distance between the crosslinking points is achieved, and as a result, an effect of reducing the peeling force is obtained. By making the addition amount of LPD 50 parts by mass or less, it is possible to prevent the curing due to active energy ray irradiation from becoming insufficient.

In the present invention, the release agent composition may contain an antioxidant.
The antioxidant is not particularly limited, and any of various known phosphite antioxidants, organic sulfur antioxidants, hindered phenol antioxidants, and the like can be used.
These antioxidants may be used individually by 1 type, and may be used in combination of 2 or more type. In addition, the amount used is 0.01 parts by mass with respect to 100 parts by mass of the diene polymer compound (total amount of PD and LPD) from the viewpoint of suppressing heavy release due to deterioration of the diene polymer compound. From the viewpoint of sufficiently maintaining the adhesion between the release agent and the release sheet substrate, the content is preferably 10 parts by mass or less with respect to 100 parts by mass of the diene polymer compound. More preferably, it is the range of 0.05-5 mass parts with respect to 100 mass parts of diene polymer compounds.
Other components (such as an antistatic agent, a photoinitiator, a plasticizer, and a stabilizer) can be added to the composition for a release agent of the present invention together with an antioxidant to be blended as necessary.

Next, the release sheet will be described.
The release sheet of the present invention has a release agent layer formed by crosslinking the release agent composition of the present invention by irradiation with active energy rays on at least one surface of the release sheet substrate.
The release sheet substrate has a function of supporting the release agent layer, for example, a polyester film such as a polyethylene terephthalate film or a polybutylene terephthalate film, a polyolefin film such as a polypropylene film or a polymethylpentene film, a polycarbonate film, etc. Plastic films, metal foils such as aluminum and stainless steel, glassine paper, high-quality paper, coated paper, impregnated paper, paper such as synthetic paper, and the like. When a plastic film is used as the release sheet substrate, the surface of the plastic film on which the release agent layer is provided is optionally oxidized for the purpose of improving the adhesion between the plastic film and the release agent layer. A physical or chemical surface treatment such as a method or an unevenness method can be performed. Examples of the oxidation method include corona discharge treatment, chromic acid treatment, flame treatment, hot air treatment, ozone / ultraviolet irradiation treatment, and the like. Examples of the unevenness method include a sand blast method and a solvent treatment method. . These surface treatment methods are appropriately selected according to the type of the substrate, but in general, the corona discharge treatment method is preferably used from the viewpoints of effects and operability. Moreover, primer treatment can also be performed.

Although the average thickness of a peeling sheet base material is not specifically limited, It is preferable that it is 10-200 micrometers, and it is more preferable that it is 15-100 micrometers.
In order to form a release agent layer on at least one surface of the release sheet substrate, a solution (hereinafter referred to as a release agent solution) in which the release agent composition is dissolved in an organic solvent is applied onto the release sheet substrate. It is possible to carry out the process by subjecting it to a drying treatment as required and irradiating with an active energy ray for crosslinking.
Examples of the organic solvent include toluene, xylene, methanol, ethanol, isobutanol, n-butanol, acetone, methyl ethyl ketone, tetrahydrofuran, and ethyl acetate. These may be used individually by 1 type, and may be used in combination of 2 or more types. For the convenience of coating, the release agent solution is preferably prepared using these organic solvents so that the solid content is in the range of 0.1 to 10% by mass, more preferably 0.3. It is the range of -5 mass%.
In order to obtain a predetermined peeling force (light peeling), the coating amount of the release agent solution is preferably adjusted to an amount such that the thickness after drying is 0.01 μm or more, and blocking is caused. In order to avoid this, it is preferably 1 μm or less, particularly preferably in the range of 0.02 to 0.8 μm.
Coating of the release agent solution on the release substrate sheet, for example, bar coating method, reverse roll coating method, knife coating method, roll knife coating method, gravure coating method, air doctor coating method, doctor blade coating method, etc. It can carry out by a conventionally known coating method.

In the release sheet of the present invention, an undercoat layer can be interposed between the release sheet substrate and the release agent layer as necessary. By interposing the undercoat layer, there is an advantage that adhesion between the release sheet substrate and the release agent layer and a stable release force can be obtained. Examples of the material for forming the undercoat layer include an elastic body (hereinafter, the undercoat layer may be referred to as an “elastic body layer”). Elastic bodies include natural resins such as natural rubber, polyurethane-based, ethylene vinyl acetate copolymer rest, polyolefin-based synthetic resins, or synthetic rubbers such as styrene butadiene-based, butyl-based, ethylene-propylene-based, acrylic-based Although an elastic body formed from a material such as rubber can be used, it has solvent resistance to an organic solvent used to prepare a release agent solution, and has excellent rubber elasticity. Particularly preferred are polyurethane-based synthetic resins such as polyurethane elastomers and modified polyurethane elastomers.
The elastic layer can be formed by applying and drying an undercoat solution obtained by dissolving the above materials in an organic solvent on a release sheet substrate. Furthermore, if necessary, the solvent resistance can be improved and the adhesion between the elastic layer and the substrate can be improved by irradiating with ultraviolet rays after coating and drying. When an elastic layer is interposed, an antioxidant, a photosensitizer, or the like can be blended therein as necessary.

The organic solvent used for preparing the undercoat liquid can be appropriately selected from known solvents having good solubility in the material for forming the undercoat layer. Examples of such a solvent include toluene, xylene, methanol, ethanol, isobutanol, n-butanol, acetone, methyl ethyl ketone, tetrahydrofuran, and ethyl acetate. These may be used individually by 1 type, and may be used in combination of 2 or more types.
The undercoat liquid is adjusted so that the solid content is in the range of about 0.1 to 15% by mass, preferably 0.5 to 5% by mass using these organic solvents for convenience of coating. . The coating of the undercoat liquid on the release sheet substrate is, for example, a bar coating method, a reverse roll coating method, a knife coating method, a roll knife coating method, a gravure coating method, an air doctor coating method, a doctor blade coating method, etc. It can carry out by a conventionally known coating method.
An undercoat layer is formed by applying the undercoat liquid onto the release sheet substrate and drying it by heating at a temperature of about 40 to 160 ° C. for a time of about 30 seconds to 2 minutes. The coating amount of the undercoat liquid is preferably adjusted to an amount such that the thickness after drying is 0.01 μm or more in order to obtain the temporal peeling stability that is an effect of providing the undercoat layer. . As a thickness that does not cause blocking and is economical and efficient, 5 μm or less is preferable, and a range of 0.1 to 1 μm is particularly preferable.

After applying and drying the release agent solution on the undercoat layer of the release sheet substrate on which an undercoat layer is formed as necessary, the active energy rays to be irradiated are typically ultraviolet rays and electron beams. For example, in the case of ultraviolet irradiation, conventionally known high-pressure mercury lamps, metal halide lamps, high-power metal halide lamps, electrodeless lamps, etc. can be used as ultraviolet lamps. However, the crosslinking property of diene polymer compounds And electrodeless lamps are suitable.
In the case of ultraviolet irradiation, the irradiation amount is preferably 10 mJ / cm ² or more, more preferably 1000 mJ / cm ² or less, from the viewpoint of obtaining high adhesion between the release sheet substrate and the release agent layer. More preferably, the amount of ultraviolet irradiation in the range of 70~500mJ / cm ^2, in particular in the range of 100~300mJ / cm ² is preferred. In the case of crosslinking of a diene polymer compound by ultraviolet irradiation, it can be carried out more efficiently if a photosensitizer is added to the release agent solution.
As specific examples of photosensitizers, aromatic ketones such as benzophenone, p, p′-dimethoxybenzophenone, p, p′-dichlorobenzophenone, p, p′-dimethylbenzophenone, acetophenone, acetonaphthone and the like are good results. In addition, aromatic aldehydes such as terephthalaldehyde and quinone aromatic compounds such as methylanthraquinone can also be used. The addition amount of a photosensitizer is 0.1-10 mass parts normally with respect to 100 mass parts of diene polymer compounds, Preferably it is 1-5 mass parts.

The release agent layer in the release sheet of the present invention is composed of a material that does not substantially contain a silicone compound as described above. Thereby, in the adhesive sheet described later, the silicone compound does not migrate from the release agent layer to the adhesive layer. As a result, the silicone compound is not released from the pressure-sensitive adhesive layer after the pressure-sensitive adhesive layer is attached to the adherend. Therefore, even if the adherend is an electronic device such as a relay, the pressure-sensitive adhesive layer is unlikely to adversely affect the adherend.
The release sheet of the present invention obtained as described above has a normal release force of 30 to a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive formed by crosslinking a carboxyl group-free acrylic copolymer with a cross-linking agent. To about 500 mN / 20 mm. The normal peel force will be described in detail in a later example together with the heat-promoted post peel force.

Next, an adhesive sheet is demonstrated.
The pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer on one surface of a pressure-sensitive adhesive sheet substrate, and the pressure-sensitive adhesive layer is laminated with a release agent layer formed on at least one surface of the release sheet.
There is no restriction | limiting in particular as said adhesive sheet base material, A various thing can be used.
Specifically, polyolefins such as polyethylene and polypropylene, sheets made of resin such as polyester such as polyethylene terephthalate, polyethylene naphthalate and polybutylene terephthalate, polyimide, polyamide, etc., and these sheets subjected to metal deposition such as aluminum, high quality Papers made of paper, impregnated paper, metal foils such as aluminum foil, copper foil and iron foil, non-woven fabric, and synthetic paper are used.
The thickness of these pressure-sensitive adhesive sheet base materials is not particularly limited, and is usually in the range of about 2 to 200 μm, but is preferably in the range of about 10 to 150 μm from the viewpoint of ease of handling.

The pressure-sensitive adhesive used for forming the pressure-sensitive adhesive layer on the pressure-sensitive adhesive sheet of the present invention can be used without limitation as long as it is a non-silicone pressure-sensitive adhesive such as an acrylic pressure-sensitive adhesive, a polyester-based pressure-sensitive adhesive, or a urethane-based pressure-sensitive adhesive. Acrylic materials are preferred. Examples of the form of the pressure-sensitive adhesive include solvent type and emulsion type.
Among acrylic adhesives, it is preferable to use an acrylic copolymer that does not contain a structural unit derived from a monomer having a carboxyl group such as (meth) acrylic acid from the viewpoint of reducing the amount of generated gas. .
When the pressure-sensitive adhesive is an acrylic pressure-sensitive adhesive, a polymer mainly comprising a main monomer component that provides tackiness, a comonomer component that provides adhesiveness and cohesive force, a functional group-containing monomer component for improving crosslinking points and adhesion, or It can be composed of a copolymer. Examples of the main monomer component include acrylic acid such as methyl acrylate, ethyl acrylate, butyl acrylate, amyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, cyclohexyl acrylate, benzyl acrylate, and methoxyethyl acrylate. Examples thereof include alkyl esters and methacrylic acid alkyl esters such as butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, and benzyl methacrylate. Examples of the comonomer component include methyl acrylate, methyl methacrylate, ethyl methacrylate, vinyl acetate, styrene, acrylonitrile, and the like.
Examples of the functional group-containing monomer component include hydroxyl group-containing monomers such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, N-methylolacrylamide, and acrylamide. , Methacrylamide, glycidyl methacrylate, N-vinylmorpholine, N-allylmorpholine, N- (meth) acryloylmorpholine, and the like. By including these components, the adhesive force and cohesive force of the pressure-sensitive adhesive layer are improved.
In addition, since such an acrylic resin usually does not have an unsaturated bond in the molecule, stability to light and oxygen can be improved. Furthermore, a pressure-sensitive adhesive composition having quality and characteristics according to the application can be obtained by appropriately selecting the type and molecular weight of the monomer. As such a pressure-sensitive adhesive composition, any of a crosslinked type that undergoes crosslinking treatment and a non-crosslinked type that does not undergo crosslinking treatment may be used, but a crosslinked type is more preferred. When a cross-linked type is used, a pressure-sensitive adhesive layer with better cohesion can be formed. Examples of the crosslinking agent used in the crosslinking adhesive composition include isocyanate compounds, epoxy compounds, metal chelate compounds, metal alkoxides, metal salts, amine compounds, hydrazine compounds, and aldehyde compounds.

In order to form the pressure-sensitive adhesive layer on the pressure-sensitive adhesive sheet substrate, prepare a pressure-sensitive adhesive solution in which the pressure-sensitive adhesive is dissolved in an organic solvent, and apply this on the pressure-sensitive adhesive sheet substrate, or You may apply to the release agent layer of the said release sheet, and may laminate | stack an adhesive sheet base material on it. Examples of the organic solvent include toluene, xylene, methanol, ethanol, isobutanol, n-butanol, acetone, methyl ethyl ketone, tetrahydrofuran, and ethyl acetate.
From the convenience of coating, the concentration of the pressure-sensitive adhesive solution is adjusted using these organic solvents so that the solid content is in the range of about 5 to 60% by mass. Coating of the pressure-sensitive adhesive solution onto the pressure-sensitive adhesive sheet base material is conventionally known, for example, bar coating method, reverse roll coating method, knife coating method, roll knife coating method, gravure coating method, air doctor coating method, doctor blade coating method, etc. The coating method can be used.
The pressure-sensitive adhesive solution is applied onto the pressure-sensitive adhesive sheet substrate, or the pressure-sensitive adhesive solution is applied to the release agent layer of the release sheet, and the temperature is about 40 to 160 ° C., preferably about 90 to 120 ° C., 30 The pressure-sensitive adhesive layer is formed by heating and drying for about 2 seconds to 5 minutes, preferably about 30 seconds to 2 minutes. The coating amount of the pressure-sensitive adhesive solution is such that the thickness of the pressure-sensitive adhesive layer after drying is about 5 to 200 μm, preferably about 10 to 100 μm.
Moreover, in the adhesive used for this invention, various additives, such as a plasticizer, a tackifier, and a stabilizer, may be contained as needed.

The pressure-sensitive adhesive layer as described above preferably has a gas amount of 1.0 μg / cm ² or less in terms of n-decane when heated at 120 ° C. for 30 minutes. More preferably, it is 0.5 μg / cm ² or less. Thereby, it is possible to effectively prevent the electronic member from malfunctioning due to a gas generated when the inside of the electronic member such as a hard disk becomes hot due to use.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not restrict | limited at all by these.

[Example 1]
<Preparation of release agent composition and release sheet>
On a polyethylene terephthalate film (Mitsubishi Polyester Film Co., Ltd .: T100) having a thickness of 38 μm as a release sheet base material, a polyurethane solution [Dainippon Ink Chemical Co., Ltd .: Crisbon 5150S, solid content 50 mass% solution as an undercoat layer, Solvent methyl ethyl ketone] 100 parts by weight, isocyanate cross-linking agent [Toyo Ink Co., Ltd .: BHS8515, solid content 37.5% by weight solution, solvent methyl ethyl ketone] 5 parts by weight was diluted with methyl ethyl ketone solution to a solid content of 1% by weight and dried. The film was applied to a thickness of 0.15 μm and dried at 100 ° C. for 1 minute to form.
Next, 100 parts by mass of 1,4-polybutadiene (BR-01, Mw: 500,000, solid content 5 mass% solution, solvent toluene, described as PB1 in Table 1) manufactured by JSR as PD and Kuraray Co., Ltd. as LPD 10 parts by mass and 1 part by mass of an antioxidant (Ciba Specialty Chemicals) manufactured by 1,4-polybutadiene (LBR-305, Mw: 26000, solid content 5 mass% solution, solvent toluene, described as LPB1 in Table 1) A release agent solution prepared by diluting a release agent composition consisting of IRGANOX HP2251 (hindered phenol-based antioxidant)] with toluene to a solid content of 0.5% by mass is prepared, and the undercoat layer It was applied on the top so that the film thickness after drying was 0.1 μm, and dried at 100 ° C. for 30 seconds. Next, the coating layer is irradiated with ultraviolet light at a conveyor speed of 40 m / min (ultraviolet irradiation condition: 100 mJ / cm ² ) by a belt conveyor type ultraviolet irradiation device with one fusion H bulb 240 W / cm ² and cured. A release sheet was obtained.

<Preparation of adhesive and adhesive solution>
83.8 parts by mass of butyl acrylate, 2.0 parts by mass of methyl acrylate, 0.2 parts by mass of 2-hydroxyethyl acrylate, and 14.0 parts by mass of N-acryloylmorpholine were placed in a reactor and stirred while stirring. The polymerization reaction was carried out by raising the temperature to 90 ° C. to 90 ° C., and polymerization was carried out over 7 hours while successively adding a polymerization catalyst solution in which 0.1 part by mass of azobisisobutyronitrile was dissolved in 10 parts by mass of toluene. . After completion of the reaction, a dilution solvent (a mixed solvent of toluene and ethyl acetate) was added to prepare a 40% by mass solution of an acrylic copolymer.
2 parts by mass of trimethylolpropane-modified xylylene diisocyanate-based crosslinking agent [manufactured by Toyo Ink Manufacturing Co., Ltd., BXX5640, 35.0% by mass as a solid content] in 100 parts by mass (40% by mass as a solid content) of this acrylic copolymer solution Was mixed to prepare a solution of the pressure-sensitive adhesive composition (solid content: 39.9% by mass).

<Production of adhesive sheet>
Apply the solution of the pressure-sensitive adhesive composition on the release sheet prepared as described above using an applicator so that the film thickness after drying is about 25 μm, and heat and dry at 120 ° C. for 1 minute, An adhesive layer was formed. Thereafter, the pressure-sensitive adhesive layer on the release agent layer of the release sheet was bonded to a 38 μm-thick polyethylene terephthalate film [manufactured by Toyobo Co., Ltd .: Cosmo Shine A4100] as a pressure-sensitive adhesive sheet substrate to obtain a pressure-sensitive adhesive sheet. .

The constituent materials of the release agent layer and the compounding ratio thereof in the release sheets prepared in Example 1 and the following Examples and Comparative Examples are summarized in Table 1.
[Examples 2 to 6]
A release sheet and a pressure-sensitive adhesive sheet were prepared in the same manner as in Example 1 except that a release agent composition was prepared using the materials and mixing ratio shown in Table 1 to prepare a release agent layer.
The materials listed in Table 1 used in Example 2 and below are as follows.
LPB2 is 1,4-polybutadiene (LBR-307, Mw: 8000, solid content 5 mass%, solvent toluene) manufactured by Kuraray Co., Ltd.
LPB3 is 1,4-polybutadiene (LBR-300, Mw: 44000, solid content 5 mass%, solvent toluene) manufactured by Kuraray Co., Ltd.
PB2 is 1,4-polybutadiene (BR-730, Mw: 900,000, solid content 5 mass% solution, solvent toluene) manufactured by JSR.
PI is JSR polyisoprene (IR2200, Mw: 400,000, solid content 5 mass% solution, solvent toluene).
LPI is Kuraray's polyisoprene (LIR-30, Mw: 28000, solid content 5 mass%, solvent toluene).

[Comparative Example 1]
Example except that a release sheet (PIN 381031 manufactured by Lintec Co., Ltd.) in which a release agent layer made of a silicone release agent (described as Si in Table 1) was formed on one side of a polyethylene terephthalate film having an average thickness of 38 μm was used. A comparative pressure-sensitive adhesive sheet was prepared in the same manner as in 1.

[Comparative Examples 2 to 7]
A comparative release sheet and pressure-sensitive adhesive sheet were prepared in the same manner as in Example 1 except that a release agent layer was prepared with the materials and mixing ratio shown in Table 1.

[Test method and evaluation method]
<Normal peel force>
With respect to the pressure-sensitive adhesive sheets of each Example and each Comparative Example (after production, left for 168 hours under conditions of 23 ° C. and 50% RH), the peel strength of the release sheet was measured.
The peel strength of the release sheet is measured in accordance with JIS-Z0237, the adhesive sheet is cut into a width of 20 mm and a length of 200 mm, and the adhesion is measured using a tensile tester (Orientec, TENSILON UTM-4-100). The sheet was fixed, and the release sheet was pulled in the 180 ° direction at a speed of 300 mm / min, and the resulting release force was defined as the normal release force.
Moreover, when peeling a release sheet, it was observed whether the adhesive layer remained on a release sheet. In the case of absence, the peelability ○, and in the case of presence, the peelability ×.

<Peeling force after heat acceleration>
About the adhesive sheet of each Example and each comparative example, after producing an adhesive sheet, it was allowed to stand at 23 ° C. and 50% RH for 168 hours, and then left at 70 ° C. (70 ° C. constant temperature layer) for 168 hours. After leaving for 24 hours under 50% RH conditions, the peel strength of each release sheet was measured in the same manner as in the normal peel strength test to determine the post-heat accelerated peel strength, and the evaluation was performed based on the same criteria as the normal peel strength.

<Silicon compound transfer amount (described as Si transfer amount in Table 1)>
From the pressure-sensitive adhesive sheet, on the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer from which the release sheet was peeled, the ratio of Si element existing on the surface was measured using the following X-ray photoelectron spectrometer (measuring device: “Quantera, manufactured by ULVAC-PHI). SXM ").
In the present specification, the absence of a silicone compound means that the amount of the silicone compound measured by X-ray photoelectron spectroscopy in the release agent or pressure-sensitive adhesive is 0.1 atomic% or less. . The measurement conditions and measurement values of X-ray photoelectron spectroscopy were calculated under the following conditions.
X-ray: AlKα (1486.6 eV)
Extraction angle: 45 °
Measurement elements: silicon (Si), carbon (C), and the amount of the silicone compound are calculated by multiplying the value of Si / (Si + C) by 100 and expressed in “atomic%”.

<Measurement of generated gas amount>
The pressure-sensitive adhesive layer from which the release sheet was peeled off was heated at 120 ° C. for 30 minutes with a purge and trap (manufactured by JEOL Ltd., product name “JHS-100A”) to collect the generated gas, and then GC-MS The gas was introduced into a device (manufactured by Perkin Elmer, product name “Turbo Mass”), and the amount of gas generated was calculated in terms of n-decane. In addition, n-decane conversion amount was calculated | required from the n-decane calibration curve created beforehand by making the detection intensity of the generated gas obtained with a GC-MS apparatus into the detection intensity of n-decane.
The above results are summarized in Table 1.

  As is clear from Table 1, the release sheet of the present invention was excellent in light release performance both in the normal state and after heat acceleration. In contrast, satisfactory results were not obtained with the release sheets of the comparative examples. Further, since the pressure-sensitive adhesive sheet of the present invention does not contain a silicone compound, the amount of outgas generated is small, and it is difficult to adversely affect electronic members such as relays.

Claims (12)

  A composition for a release agent obtained by adding 2 to 50 parts by mass of a diene polymer having a weight average molecular weight of 1,000 to 100,000 to 100 parts by mass of a diene polymer having a weight average molecular weight of 300,000 to 1,200,000.   The release agent composition according to claim 1, wherein both of the diene polymer compounds are polybutadiene or polyisoprene.   The release agent composition according to claim 1, wherein both of the diene polymer compounds are 1,4-polybutadiene.   The release sheet which has a release agent layer formed by apply | coating and drying the composition for release agents in any one of Claims 1-3 to at least one surface of a release sheet base material, and forming by active energy ray irradiation.   The release sheet according to claim 4, wherein the release agent layer contains an antioxidant.   The release sheet according to claim 4 or 5, which has an undercoat layer between the release sheet substrate and the release agent layer.   The release sheet according to claim 6, wherein the undercoat layer is an elastic body made of polyurethane.   The peeling according to any one of claims 4 to 7, wherein the normal peeling force for the pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive obtained by crosslinking a carboxyl group-free acrylic copolymer with a crosslinking agent is 30 to 500 mN / 20 mm. Sheet.   A pressure-sensitive adhesive sheet obtained by laminating a surface of the release agent layer of the release sheet according to claim 4 and a pressure-sensitive adhesive layer formed on at least one surface of the pressure-sensitive adhesive sheet substrate.   The pressure-sensitive adhesive sheet according to claim 9, wherein the pressure-sensitive adhesive layer is a layer obtained by crosslinking a carboxyl group-free acrylic copolymer with a crosslinking agent. The pressure-sensitive adhesive sheet according to claim 9 or 10, wherein the amount of gas generated when the pressure-sensitive adhesive layer is heated at 120 ° C for 30 minutes is 1.0 µg / cm ² or less in terms of n-decane.   It is an adhesive sheet for electronic members, The adhesive sheet in any one of Claims 9-11.