JPH1120107A - Silicone easily adhesive film and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyethylene-2,6-naphthalate film having excellent heat-resistant dimensional stability and excellent adhesion to silicone, and to produce the film with high productivity. Provide a way to SOLUTION: A crosslinked primer layer obtained by applying an aqueous liquid of a thermocrosslinkable polyurethane prepolymer having an unsaturated double bond to at least one surface of a polyethylene-2,6-naphthalate film, followed by drying and heat crosslinking. Wherein the dimensional change rate due to thermal stress after heating the silicone easy-adhesive film at 120 ° C. for 30 minutes is 0 to 0.10 in the longitudinal direction.
%, And 0 to 0.05% in the transverse direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an easily-adhesive silicone film and a method for producing the same, and more particularly, to a film having excellent releasability, easy-to-adhesive silicone, and a heat treatment (for drying when applying silicone). Heat treatment), the heat-shrinkable adhesive film which does not thermally shrink, and a method for producing the same.

[0002]

2. Description of the Related Art A release film is used as a protective film for an adhesive surface such as an adhesive, an adhesive, a patch or a urethane resin.
It is used as a carrier for molding a sheet of a curable resin such as an epoxy resin or an unsaturated polyester resin, or a sheet of a thermoplastic resin, and its amount is expanding. Along with this, the production speed at the time of producing sheets has been increased year by year, and the drying temperature has been increased to a higher temperature than in the past in order to quickly dry the solvent used at the time of sheet molding. In addition, the demands on the dimensional accuracy of the sheet obtained by molding have become higher year by year, and it has become necessary to reduce the dimensional change and deformation of the release film even when drying the solvent at a higher temperature than before. .

[0003] As such a release film, conventionally,
A polyester film typified by a polyethylene terephthalate film is provided on at least one side with a coating made of an addition-polymerized cured product of a silicon compound having a vinylsiloxane group or a condensation-polymerized cured product of an alkyloxysilane or oxysilane compound. .

However, if the drying temperature of the solvent is higher than in the past, for example, in a release film using polyethylene terephthalate as a base film, the dimensional change rate due to thermal stress is large, and dimensional accuracy may not be satisfied. There is a need for improvements.

On the other hand, the above-mentioned cured silicone for forming the release layer has the advantage that it is non-adhesive and has excellent release effect and thermal stability, but on the other hand, it has insufficient adhesion to the polyester film as the base film. Have a problem.

Therefore, as a method for improving the adhesion between the cured silicone layer and the polyester film, there has been proposed a method of providing a crosslinked primer layer using a silane coupling agent (JP-A-1-5838). However, this method has a problem that the reactivity of the silane coupling agent is slow and the productivity is low. In order to improve the reactivity, a platinum-based catalyst or the like is added in a solvent system, but this catalyst has a drawback that it is hardly soluble in water or loses its catalytic activity even if dissolved. Not suitable for liquids.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve such a problem and to provide an easy-to-bond silicone having excellent adhesion to a cured silicone layer and dimensional stability during heat treatment (heat-resistant dimensional stability). To provide a functional film.
Another object of the present invention is to provide a method for producing the above-mentioned silicone adhesive film with high productivity.

[0008]

The present invention has the following structure to achieve the above object. A. Polyethylene-
At least one surface of a 2,6-naphthalate film is coated with an aqueous liquid of a thermo-crosslinkable polyurethane prepolymer having an unsaturated double bond, and then dried and thermally cross-linked to provide a silicone primer having a cross-linked primer layer. Dimensional change rate due to thermal stress after heat-treating the silicone adhesive film at 120 ° C. for 30 minutes is 0 to 0.10% in the vertical direction and 0 to 0.05% in the horizontal direction.
An easily adhesive silicone film characterized by the following:
I. At least one surface of the polyethylene-2,6-naphthalate film before the completion of the crystal orientation has an unsaturated double bond in the molecule and a blocked isocyanate group, and is water-soluble or water-dispersible. A composition mainly composed of a heat-crosslinkable polyurethane prepolymer, followed by drying, stretching and heat treatment to complete the crystal orientation of the film and to make the coating layer thermally crosslinkable. A method for producing a functional film,
After the silicone easy-adhesive film was heated at 120 ° C. for 30 minutes, the dimensional change due to thermal stress was 0 in the vertical direction.
0.10% and 0 to 0.05% in the transverse direction.
Hereinafter, the present invention will be described in more detail.

[Polyethylene-2,6-naphthalate film] [Polyethylene-2,6-naphthalate] In the present invention, polyethylene-2,6-naphthalate (hereinafter referred to as PEN) constituting the polyethylene-2,6-naphthalate film
Is a crystalline linear saturated polyester obtained by polycondensation of naphthalene-2,6-dicarboxylic acid or an ester-forming derivative thereof and ethylene glycol or an ester-forming derivative thereof. Such P
The EN polymer may be a homopolymer, a copolymer obtained by copolymerizing a small proportion of copolymer components (for example, 10 mol% or less, particularly 5 mol% or less), or a small proportion of another polymer (for example, 20 wt% or less, particularly 10 wt% or less). The following may be blended blended polymers.

Preferred copolymerization components include compounds having two ester-forming functional groups, such as oxalic acid, adipic acid, phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,7-dicarboxylic acid, 4,4 Dicarboxylic acids such as' -diphenyl ether dicarboxylic acid or lower alcohol esters thereof, p-oxybenzoic acid,
an oxycarboxylic acid such as p-oxyethoxybenzoic acid or an ester-forming derivative thereof;
And dihydric alcohols such as propylene glycol, 1,3-propylene glycol, 1,4-tetramethylene glycol, 1,6-hexamethylene glycol, neopentyl glycol and the like.

Further, the PEN polymer may be a polymer in which a terminal hydroxyl group and / or a carboxyl group is partially or entirely blocked by a monofunctional compound such as benzoic acid or monomethoxypolyalkylene glycol, or For example, it may be obtained by copolymerizing a very small amount of an ester-forming compound having three or more functions such as glycerin and pentaerythritol within a range where a substantially linear polymer can be obtained.

[0012] The PEN polymer can be produced by a known method. For example, it can be produced by polycondensing naphthalene-2,6-dicarboxylic acid or an ester-forming derivative thereof and ethylene glycol or an ester-forming derivative thereof in the presence of a catalyst. When a copolymer is produced, a copolymer component may be added together with the above components.

[Film] As the PEN film in the present invention, a film containing no lubricant is preferable in terms of surface smoothness, but a lubricant for controlling the surface roughness, for example, calcium carbonate, kaolin, silica, alumina, titanium oxide A film containing inorganic fine particles or the like as described above may be used. Further, the film may contain other additives such as a stabilizer, an ultraviolet absorber, a flame retardant, and an antistatic agent.

The thickness of the PEN film in the present invention is preferably 5 to 200 μm, more preferably 25 to 10 μm.
0 μm.

For the purpose of enhancing the adhesion of the release layer, the surface of the PEN film used in the present invention is preferably subjected to a corona treatment.

[Primer Layer] In the present invention, the crosslinked primer layer provided on at least one side of the PEN film is a thermally crosslinked polyurethane layer formed by thermally crosslinking a polyurethane prepolymer having an unsaturated double bond.

The crosslinked primer layer in the present invention is formed by coating a polyurethane prepolymer having an unsaturated double bond in a molecule among the thermocrosslinkable prepolymers, on a film, and thermally crosslinking. The polyurethane prepolymer having an unsaturated double bond can be obtained by reacting a polyol with an organic polyisocyanate.

An unsaturated double bond is present in the thermocrosslinkable polyurethane layer, and the unsaturated double bond is preferably derived from a polyol component constituting the heat crosslinkable polyurethane polymer. The unsaturated double bond in the heat-crosslinkable polyurethane layer can be introduced by using a polyol having an unsaturated double bond in part or all of the polyol component. The proportion of the polyol having an unsaturated double bond is preferably at least 10% by weight based on all the polyol components.

When the unsaturated double bond is present in the crosslinked primer layer, a strong adhesive force with the silicone layer can be obtained.

Preferred examples of the polyol having an unsaturated double bond include unsaturated polyester polyols.

Specific examples of unsaturated polyester polyols include an unsaturated polyester polyol comprising an unsaturated polycarboxylic acid component and a saturated polyhydric alcohol component.
Unsaturated polyester polyols obtained by polycondensation of a saturated polycarboxylic acid component and an unsaturated polyhydric alcohol component; of the above unsaturated polyester polyols, saturated polyhydric alcohols or unsaturated polyester polyols; Unsaturated polyester polyols in which the saturated polyhydric alcohol is a mixture of a saturated polyhydric alcohol and an unsaturated polyhydric alcohol; and saturated polycarboxylic acids or unsaturated polycarboxylic acids are unsaturated Examples thereof include unsaturated polyester polyols which are a mixture with a saturated polycarboxylic acid.

Examples of the unsaturated polycarboxylic acid component include maleic acid and fumaric acid components.

Examples of the saturated polycarboxylic acid component include adipic acid, sebacic acid, terephthalic acid, and isophthalic acid.

As the saturated polyhydric alcohol component, ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, neopentyl glycol,
Hexamethylene glycol and trimethylolpropane can be exemplified.

As the unsaturated polyhydric alcohol component, butenediol; 1,2-polybutadienepolyol, 1,4
-Polybutadiene polyols such as polybutadiene polyol; obtained by copolymerizing various acrylic acid monomers with acrylic acid monomers having a hydroxyl group such as hydroxyethyl acrylate and hydroxymethacrylate. Acrylic polyols having a hydroxyl group in the chain measurement can be exemplified. Of these, polybutadiene polyols are preferred.

The polyol having an unsaturated double bond may be used alone or as a mixture.
Further, it may be used in combination with a compound having two or more active hydrogens usually used for producing polyurethane.

Compounds having two or more active hydrogens include saturated polyester polyols, polyether polyols (eg, polyethylene glycol, polytetramethylene glycol, etc.) and amino alcohols (eg, ethanolamine, diethanolamine, triethanolamine, etc.). Ethanolamine).

The isocyanate used in the present invention includes, for example, aromatic polyisocyanates such as diphenylmethane diisocyanate and toluene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate; xylene Aromatic / aliphatic polyisocyanates such as diisocyanate; and polyisocyanates obtained by previously reacting these isocyanates with low molecular weight polyols such as trimethylolpropane.

The polyurethane prepolymer used in the present invention has thermal crosslinking properties. In the present invention, the polyurethane prepolymer has an excess of the number of moles of isocyanate groups relative to the sum of the hydroxyl groups and active hydrogen (number of moles),
Preferably, the molar ratio is 1.1 to 2.0 times excess, and two or more unreacted isocyanate groups are present for each prepolymer molecule produced.

It is preferable that the terminal of this isocyanate group is blocked by using a blocking agent (hereinafter, this terminal blocking may be simply referred to as blocking). Particularly, in order to suitably prepare an aqueous coating solution, This blocking is essential. This blocking is well known as blocking of isocyanates, and is a blocking in which free isocyanate groups can be regenerated by heating.

Examples of the blocking agent include bisulfites such as sodium bisulfite; alcohols such as isopropyl alcohol and tertiary butyl alcohol; oximes such as butane oxime, methyl ethyl ketone oxime and cyclohexanone oxime; and activity such as acetylacetone. Methylene compounds; phenols such as phenol and alkyl phenol; isodazoles such as imidazole; other lactams, imine compounds, amide compounds;
Examples include imide compounds.

The reaction between these blocking agents and isocyanate groups in the polyurethane prepolymer is carried out at room temperature to 10
The reaction can be carried out at a temperature of 0 ° C., and the urethanization catalyst can be used if necessary in this reaction.

The polyurethane prepolymer used in the present invention preferably has water dispersibility and water solubility.

It is preferable to impart stable water dispersibility or water solubility to the polyurethane prepolymer by introducing a hydrophilic group into the molecule.

[0035] Such hydrophilic groups include -SO ₃ M
A group (where M is an alkali metal or an alkaline earth metal), a —OH group, and a —COOR group (where R is a residue of ammonia or a tertiary amine) is preferable;
Among these, a carboxyl group (—COOR group) neutralized with ammonia or a tertiary amine is particularly preferable.

The introduction of a carboxyl group neutralized with ammonia or a tertiary amine into a polyurethane prepolymer is carried out, for example, by using a carboxyl group-containing polyhydroxy compound as one of the reaction raw materials during the synthesis of the polyurethane prepolymer. Or a non-reacted isocyanate group in a polyurethane prepolymer having an unreacted isocyanate group is reacted with a carboxylic acid containing a hydroxyl group or a carboxylic acid containing an amino group, and then the resulting reaction product is mixed with aqueous ammonia under high-speed stirring. Alternatively, it can be carried out by adding to a tertiary amine aqueous solution and neutralizing it. The amount of the carboxyl group or base to be introduced is preferably 0.1 to 15% by weight based on the polyurethane prepolymer.

Examples of the carboxylic acid having a hydroxyl group include dimethylolpropionic acid, dimethylolbutyric acid, dimethylolvaleric acid, trimellitic acid bis (ethylene glycol) ester, 3-hydroxypropionic acid, γ-hydroxybutyric acid, p- (2-hydroxy Ethyl) benzoic acid,
Malic acid can be mentioned.

Examples of the amino group-containing carboxylic acid include glycine, alanine, β-aminopropionic acid, γ-aminobutyric acid, and p-aminobenzoic acid.

The base used for neutralizing the carboxyl group may be ammonia; tertiary amines such as trimethylamine, triethylamine, tripropylamine, tributylamine, triethanolamine, methyldiethanolamine, dimethylethanolamine and diethylethanolamine.
Secondary amines can be exemplified.

The synthesis of the polyurethane prepolymer used in the present invention is carried out in the presence of a usual urethanization catalyst, for example, an organic acid, an inorganic acid, an amine compound or a metal-based catalyst at room temperature (2 ° C.).
(5 ° C) to 100 ° C.

This reaction may be carried out in the absence of a solvent or in the presence of an organic solvent. As the organic solvent used for the reaction, a hydrophilic solvent which is inactive with isocyanate and has a boiling point of 100 ° C. or lower or azeotropic with water at 100 ° C. or lower is preferable. As such a solvent, for example,
Acetone, tetrahydrofuran, methyl ethyl ketone,
Dioxane and ethyl acetate can be mentioned.

The molecular weight of the polyurethane prepolymer is 1
000-3000 is preferred.

[Coating Liquid] The polyurethane prepolymer used in the present invention is coated on a film as a coating liquid and used for forming a primer layer. The solid content in the coating liquid is preferably 1 to 30% by weight. Especially 2 to 10% by weight
Is preferred. If the solid concentration exceeds 30% by weight, the stability of the coating solution or the solubility of the solid may be poor, and it may be difficult to apply the coating solution uniformly. If the solid content is less than 1% by weight, coating defects such as repelling spots are likely to occur, which is not preferable.

The coating amount of the coating solution is preferably 0.5 to ²⁰ g, particularly preferably 1 to 10 g per 1 m ² of the running film. If the coating amount is less than 0.5 g / m ² , the adhesiveness to silicone may be insufficient, and 20 g / m ²
If it exceeds m ² , cohesive failure of the coating film tends to occur.

The coating solution is preferably an aqueous primer coating solution. Here, the aqueous primer coating solution is obtained by dissolving or uniformly dispersing the above polyurethane prepolymer in water. The aqueous primer coating solution can contain a required amount of a surfactant such as an anionic surfactant, a cationic surfactant, or a nonionic surfactant.

As the surfactant, the surface tension of the coating solution is 50 dyne / cm or less, preferably 40 dyne / c.
m or less, and preferably promotes wetting to the PEN film. As a surfactant, for example, polyethylene oxide-polypropylene oxide block copolymer, polyoxyethylene alkyl ether,
Examples thereof include polyoxyethylene alkylphenyl ether, polyoxyethylene monoalkylate, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, and glycerin fatty acid ester.

Further, in the coating solution, for example, an antistatic agent, an ultraviolet absorber, a pigment, and the like, as long as the effects of the present invention are not impaired.
Other additives such as an inorganic filler, an organic filler, a lubricant, and an antiblocking agent can be mixed.

An example of a method for producing an aqueous primer coating solution will be described.

Polybutadiene polyol (molecular weight 200
0) 16.8 parts by weight of hexamethylene diisocyanate is added to a mixture of 70 parts by weight and 30 parts by weight of polyethylene glycol (molecular weight: 2,000), and reacted while maintaining the temperature at 100 ° C. or lower to obtain a polyurethane prepolymer having a free isocyanate group. .

Next, 50 parts by weight of methyl ethyl ketone was added to this prepolymer, and 3.3 parts by weight of dimethylolpropionic acid were further added thereto and reacted to form a polyurethane prepolymer having about half of the free isocyanate groups blocked. Get. Further, 4.4 parts by weight of butanone oxime was added to the prepolymer and allowed to react. After the free isocyanate groups had completely disappeared, triethylamine 2.
Neutralize by adding 5 parts by weight. The obtained reaction product is diluted with water to obtain an aqueous primer coating solution.

The coating liquid is applied to at least one side of the PEN film, and then dried and thermally crosslinked to provide a crosslinked primer layer. The application of the heat-crosslinkable polyurethane prepolymer as a water-soluble primer coating solution to the PEN film is preferably performed in the process of manufacturing the PEN film.

The coating may be performed in a usual primer coating step. When applying a coating liquid to a previously manufactured biaxially stretched and heat-fixed PEN film separately from the manufacturing process, it is desirable to apply the coating in a clean atmosphere because dust and the like are easily involved.

As a method for applying the coating solution to the PEN film, any known coating method can be applied. For example, a roll coating method, a gravure coating method, a microgravure coating method, a reverse coating method, a roll brushing method, a spray coating method, an air knife coating method, an impregnation method, and a curtain coating method can be applied alone or in combination. The coating liquid may contain a small amount of an organic solvent for the purpose of assisting the stability or coating property of the coating liquid.

The coating is preferably performed during the PEN film manufacturing process. Further, it is more preferable from the viewpoint of adhesiveness to apply the aqueous coating solution to one or both surfaces of the PEN film before the completion of the crystal orientation in this step.

Here, as the PEN film before the crystal orientation is completed, the unstretched film which is obtained by melting PEN as it is, and the unstretched film is formed in the longitudinal direction (longitudinal direction) or the transverse direction (width direction) Uniaxially stretched film and a biaxially stretched film stretched at a low magnification in two directions, longitudinally and transversely (finally stretched in the longitudinal or transverse direction to complete the orientation crystallization) Biaxially stretched film).

The PEN film coated with the coating solution is subjected to a thermal crosslinking treatment. Before the thermal crosslinking treatment, the water content of the aqueous solution of the coating solution is usually dried.

When the coating solution is applied to a vertically uniaxially stretched PEN film, the coating solution is dried and thermally crosslinked while the PEN film is guided by a stenter and heated, and then horizontally stretched and heat-set. .

The crosslinked primer layer in the present invention is made of PE
It has excellent adhesion to N films and excellent adhesion to silicone.

Accordingly, when a silicone release layer is provided on the crosslinked primer layer using the silicone adhesive film of the present invention, a release film having excellent durability and heat-resistant dimensional stability can be obtained.

[Dimensional Change Due to Thermal Stress] The dimensional change due to thermal stress in the longitudinal direction (longitudinal direction) of the easily adhesive silicone film of the present invention when subjected to heat treatment at 120 ° C. for 30 minutes is 0 to 0. It is necessary that the dimensional change rate due to thermal stress in the lateral direction (width direction) is 0% to 0.05%.

[Plane Orientation Coefficient] In the present invention, PE
The N film has a plane orientation degree of 0.10 determined by the following formula (1).
A biaxially oriented PEN film of up to 0.30 is preferred because the mechanical properties of the release film become better.

[0062]

Ns = (nx + ny) / 2-nz [where ns represents the degree of plane orientation, nx represents the refractive index in the horizontal direction, ny represents the refractive index in the vertical direction, and nz represents the refractive index in the thickness direction. . ]

The PEN film of the present invention has a density of 1.340 g / cm ³ or more, and more preferably 1.350 g / cm ^3.
As described above, in particular, it is preferably 1.360 g / cm ³ or more because the dimensional change rate due to thermal stress of the release film becomes good.

[Production Method of PEN Film] The PEN film used in the present invention can be produced by a conventionally known method. For example, a PEN polymer is dried and then melted, extruded from a die (for example, a T die, an I die, etc.) onto a cooling drum and cooled to form an unstretched film,
The unstretched film is stretched in the machine direction at a temperature of 130 to 150 ° C. at a magnification of 3.0 to 4.5 times, and then in the transverse direction at 12 to 4.5 times.
It can be obtained by a method of stretching at a temperature of 0 to 150 ° C. at a magnification of 3.2 to 4.8 times (sequential biaxial stretching) or a method of simultaneously stretching in the machine direction and the transverse direction (simultaneous biaxial stretching). it can. At this time, by setting the stretching ratio in the vertical direction and the horizontal direction to be substantially the same, the isotropy of the film can be improved.

The PEN film used in the present invention is a PEN film having a specific plane orientation coefficient, a specific range of density, and a dimensional change rate due to thermal stress. This film is obtained by stretching a biaxially stretched film at 220 to 255 ° C for 5 seconds. It can be obtained by heat setting for ~ 1 minute. The heat setting is preferably performed while restricting shrinkage. In particular, after heat-setting the biaxially stretched film, the film is heat-treated (heat-relaxed) in a relaxed state at a temperature of 120 to 150 ° C., whereby a film having a more preferable dimensional change rate due to thermal stress can be obtained.

Further, the orientation crystallization of the PEN film is as follows:
In addition to the above conditions, stretching and heat setting can be performed under conditions conventionally accumulated in the art.

[Silicone Release Layer] When the silicone adhesive film of the present invention is used as a release film, a silicone release layer is provided on the crosslinked primer layer.

For the silicone release layer, for example, a polyorganosiloxane having an unsaturated hydrocarbon group such as a vinyl group and a polyorganosiloxane having a hydrogen atom directly bonded to a silicon atom are subjected to an addition reaction using a platinum compound as a catalyst. Cured film obtained by using a polyorganosiloxane having a hydroxyl group bonded to a silicon atom and an organosilane or polysiloxane having a hydrolyzable functional group (for example, an alkoxy group, an oxime group or an acetoxy group) with an organotin or organotitanium compound Preferred is a cured film obtained by a condensation reaction with a catalyst.

Such a cured film is formed by applying a coating solution containing a component for forming the film on the primer layer and curing the coating solution on the primer layer.

The components forming the film include, for example, toluene,
It is prepared as a coating solution by dissolving it in a solvent such as ethyl acetate, n-hexane, methyl ethyl ketone, or cyclohexanone.This coating solution may contain a trace amount of a catalyst such as an organic platinum compound for accelerating the polymerization reaction. preferable.

As a method of applying this coating solution, for example,
A gravure coating method, a microgravure coating method, a reverse coating method, a spray coating method, and a bar coating method can be used.

The thickness of the formed silicone release layer is 0.01 to 10 μm in a dry state, more preferably 0.02 to 5 μm.
μm is preferred. When the thickness is less than 0.01 μm, the releasability is insufficient. When the thickness is more than 10 μm, transfer of silicone to an adhesive due to insufficient polymerization is not preferred.

The release layer thus obtained is excellent in adhesion to the PEN film via the primer layer, has little transfer of the release layer component to an adhesive or the like, and has excellent durability.

In the easily adhesive silicone film of the present invention, a silicone release layer whose components are selected according to the intended use can be provided on the crosslinked primer layer.

The easily adhesive silicone film of the present invention comprises
It has the following advantages in its physical properties.

When compared with the unstretched film, the PEN film has a glass transition temperature of about 120 ° C., which is significantly higher than that of the polyethylene terephthalate film (78 ° C.). When compared with biaxially stretched films, the glass transition temperature is increased due to the increase in crystallinity due to molecular orientation.
The temperature is about 160 ° C. for a PEN film and about 120 ° C. for a polyethylene terephthalate film.

The temperature in the drying step after application of a resin solution or the like is generally in a temperature range of about 60 to 140 ° C. In this temperature range, especially in a high temperature range, the temperature exceeds the glass transition temperature of the biaxially stretched polyethylene terephthalate film, and when the temperature is applied for a long time, the film tends to undergo thermal deformation such as shrinkage, and elongation under tension. It is easy to happen. On the other hand, the biaxially stretched PEN film has a glass transition temperature much higher than the drying step temperature, and thus has an advantage that such thermal deformation such as shrinkage and elongation hardly occurs even with a long-term heat history.

[0078]

The present invention will be further described below with reference to examples. In addition, each characteristic value of the film was measured and evaluated by the following methods. However, a film in which a release layer is coated on the easily adhesive surface (crosslinked primer layer) of the silicone easily adhesive film may be simply referred to as a release film.

(1) Back non-transferability The release layer coated surface of the release film and the release layer non-coated surface are overlapped, a load of 6 kg / cm ² is applied, and the film is held for 18 hours. A line was drawn on the surface on which the layer was not coated with an oil-based felt-tip pen (magic ink), and the degree of "repelling" was observed. ◎: No repelling ………… Back non-transfer property is extremely good △: Slight repelling slightly …… Slight back non-transfer property slightly poor ×: Repelling ………… Back non-transfer property poor

(2) Release Property A cellophane tape having a width of 24 mm was pressure-bonded to the release layer-coated surface of the release film with a rubber roll, and the peel strength between the release layer-coated surface and the cellophane tape (peel resistance: g) / 24 mm) was measured with an Instron-type tensile tester under peeling conditions in the direction of 180 °. In addition, it is preferable that the peel strength is less than 10 g / 24 mm because the releasability becomes good.

(3) Silicone easy adhesion (a) Initial easy adhesion The release layer surface of the release film immediately after the release layer is applied (immediately after coating and drying) is rubbed several times with a fingertip, and the release layer falls off. And the state of close contact were observed, and the initial easy adhesion was evaluated based on the following criteria. (B) Durability and adhesion After releasing the release film in an atmosphere of 60 ° C. × 80% RH for one week, the surface of the release layer was rubbed several times with a fingertip, and the release layer was observed to be detached and adhered. The durable adhesion was evaluated according to the following criteria. [Evaluation Criteria] ：: No change in the release layer is observed at all ………… Good adhesion property ○: Whitening due to peeling of the release layer is slightly observed ……… Easy adhesion is slightly good △: Whitening due to peeling of the release layer is observed in almost all areas. Slightly poor adhesion. ×: The release layer is completely peeled and lost.

(4) Dimensional change rate due to thermal stress A strip-shaped film (before coating with a release layer) cut out at a length of 30 mm or more and a width of 4 mm in the measurement direction was subjected to TMA (thermal stress strain measuring apparatus, Seiko Denshi Kogyo Co., Ltd.). TMA / SS12 made by company
0C), the film was mounted so that the distance between the chucks was 10 mm, a stress of 150 gf / mm ² was applied to the film, and the film was heated from room temperature at a rate of 5 ° C./min. The dimensional change under a stress of / mm ² was measured for each of the stress direction (longitudinal direction) and the vertical direction (width direction), and calculated by the following formula.

[0083]

## EQU4 ## Dimensional change rate (%) = (dimensional change / distance between chucks) × 100

(5) Density: Measured at 30 ° C. using a density gradient tube using carbon tetrachloride and n-heptane as a density gradient liquid.

[Examples 1-3 and Comparative Examples 1-2] 35 ° C.
0.6 measured in o-chlorophenol.
PEN of 0 (silica fine particles having an average particle diameter of 0.1 μm are used as a PEN).
2% by weight) was melted by an extruder, and the film-like molten polymer was extruded from a die onto a rotating cooling drum maintained at about 40 ° C., and the film-like molten polymer was formed by electrostatic adhesion. -Was quenched while being closely attached to a cooling drum to obtain an unstretched film.

Next, the unstretched film was stretched 3.7 times in the machine direction at 140 ° C. to obtain a uniaxially stretched film. An aqueous coating solution having a solid content concentration of 4% by weight having a composition shown in Table 1 was applied to one surface of the uniaxially stretched film by a kiss coating method.

Subsequently, the film was stretched 3.8 times in the horizontal direction at 130 ° C., heat-set at 240 ° C., and the thickness was 50 μm.
A biaxially stretched PEN film having a crosslinked primer layer was obtained. The density of this biaxially oriented film is 1.360 g / cm
^{3. The} degree of plane orientation was 0.20.

Next, a curable silicone resin (KS-772, manufactured by Shin-Etsu Chemical Co., Ltd.) of a type in which a platinum catalyst is added to a mixed solution of polydimethylsiloxane and methylhydrogenpolysiloxane to cause an addition reaction and cure is added to toluene. By dissolving, a solution having a solid content concentration of 5% was prepared. This solution was applied onto the above-mentioned crosslinked primer layer of the biaxially stretched PEN film at a coating amount of 1 g / m ² , and dried and crosslinked at 140 ° C. for 1 minute to obtain a release film. Table 2 shows the evaluation results of these release films.

Comparative Example 3 Polyethylene terephthalate having an intrinsic viscosity of 0.65 measured in o-chlorophenol at 35 ° C. was melted by an extruder, and the molten polymer in a film was maintained at about 20 ° C. from a die. The molten polymer in the form of a film was rapidly cooled while being in close contact with the cooling drum using an electrostatic adhesion method to obtain an unstretched film. Next, the unstretched film was stretched 3.6 times in the machine direction at 80 ° C. to obtain a uniaxially stretched film.

An aqueous coating solution having a solid content of 4% by weight as shown in Table 1 was applied to one surface of the uniaxially stretched film by a kiss coating method. Subsequently, the film is stretched 3.8 times in the transverse direction at 120 ° C.
Further, heat fixing was performed at 220 ° C. to obtain a biaxially stretched polyethylene terephthalate film having a crosslinked primer layer having a thickness of 50 μm. The density of this biaxially oriented film is 1.
365 g / cm ³ and the plane orientation degree were 0.28.

Next, a release film was obtained in the same manner as in Example 1. Table 2 shows the evaluation results of the release film.

[0092]

[Table 1]

[0093]

[Table 2]

As is evident from the results shown in Table 2, the release film using the silicone easy-adhesive film of the present invention has a back non-transfer property, a mold release property, an initial silicone easy adhesive property,
It is excellent in durability silicone easy adhesion and heat dimensional stability.

[0095]

According to the present invention, there is provided an easily-adhesive PEN film having excellent heat-resistant dimensional stability and excellent adhesiveness to silicone, and a method for producing the film with high productivity. be able to.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08J 7/00 301 C08J 7/00 301 7/04 CER 7/04 CRE B29K 67:00 B29L 9:00

Claims (6)

[Claims] 1. A cross-linked primer obtained by applying an aqueous liquid of a thermo-crosslinkable polyurethane prepolymer having an unsaturated double bond to at least one surface of a polyethylene-2,6-naphthalate film, followed by drying and heat cross-linking. A silicone-adhesive film provided with a layer, wherein the dimensional change due to thermal stress after heat-treating the silicone-adhesive film at 120 ° C. for 30 minutes is 0 to 0.10 in the vertical direction.
%, And 0 to 0.05% in the transverse direction. 2. The polyethylene-2,6-naphthalate film has a degree of plane orientation of 0. 0 determined from the following formula (1).
2. The silicone adhesive film according to claim 1, which is a biaxially oriented polyethylene-2,6-naphthalate film of 10 to 0.30. [Mathematical formula-see original document] ns = (nx + ny) / 2-nz [where ns represents the degree of plane orientation, nx represents the refractive index in the horizontal direction, ny represents the refractive index in the vertical direction, and nz represents the refractive index in the thickness direction. . ] 3. The method according to claim 1, wherein at least 10% by weight (based on the total polyol component) of the polyol component constituting the heat-crosslinkable polyurethane prepolymer is a polyol having an unsaturated double bond. The easily adhesive silicone film according to the above. 4. The silicone adhesive film according to claim 3, wherein the polyol having an unsaturated double bond is an unsaturated polyester polyol and / or a polybutadiene polyol. 5. Polyethylene before completion of crystal orientation.
At least one surface of the 2,6-naphthalate film has a water-soluble or water-dispersible, heat-crosslinkable polyurethane prepolymer having an unsaturated double bond in the molecule and having a blocked isocyanate group. A method for producing a silicone easily-adhesive film, comprising applying a composition as a component, followed by drying, stretching, and heat treatment to complete the crystal orientation of the film and heat-crosslinking the applied layer, The silicone adhesive film has a dimensional change rate of 0 to 0.10% in the vertical direction and 0 to 0.05% in the horizontal direction due to thermal stress after heat treatment at 120 ° C. for 30 minutes.
A method for producing an easily adhesive silicone film. 6. The polyethylene-2,6-naphthalate film has a degree of plane orientation of 0. 0 determined from the following formula (1).
The method for producing a silicone easily-adhesive film according to claim 5, which is a biaxially oriented polyethylene-2,6-naphthalate film of 10 to 0.30. [Mathematical formula-see original document] ns = (nx + ny) / 2-nz [where ns represents the degree of plane orientation, nx represents the refractive index in the horizontal direction, ny represents the refractive index in the vertical direction, and nz represents the refractive index in the thickness direction. . ]