JPH10286921A - Release film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a release film excellent in adhesion and release properties with time between a fine cell-containing polyester film and a hardening silicone resin coat. SOLUTION: A release film is provided with a primer layer, which is coated with, on one side of a fine cell-containing polyester film, at least one type of resin selected from water solubility or water-dispersed polyester resin, water solubility or water-dispersed polyurethane resin, or water solubility or water dispersed polyacrylate resin, and a coating containing at least one crosslinking agent composed of either melamine or epoxy. And a silicone release layer is provided on the primer layer. The fine cell-containing polyester film contains 5-45 wt.% thermoplastic resin, which is substantially incompatible with polyester, and the density is 0.4-1.3 g/cm<3> .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a release film, and more particularly, to a release film having excellent adhesion with time between a fine-bubble-containing polyester film and a cured silicone resin coating film and release properties with an adhesive or the like. Mold film. More specifically, the present invention is a release film suitable for a release film for an electronic seal photograph and the like, and is thermally transferred to a substrate surface via an adhesive laminated on the back surface or the release layer side of the release film. The present invention relates to a release film capable of obtaining a clear image or the like due to its cushioning property when printed by a method or the like.

[0002]

2. Description of the Related Art Conventionally, various release films coated with a silicone resin for protecting an adhesive surface such as an adhesive or the like have been developed, but JP-A-47-34447 discloses a condensation film. A silicone resin composition which cures by a reaction, Japanese Patent Publication No. 52-40918, describes a silicone release film which cures by an addition reaction.

[0003] Conventional release films are mainly release films in which a silicone resin coating film having releasability is formed on a substrate such as a polyester film. Is known to have poor adhesion to the As a method for improving the adhesion to the substrate, for example, JP-A-64-5838 and JP-A-3-1200
No. 42 describes a method in which an undercoat layer using a silane coupling agent is provided on a polyester surface, and a release layer is provided thereon.

However, in the method of providing an undercoat layer using a silane coupling agent on a polyester surface, a part of the silane coupling agent evaporates in a step of providing an undercoat layer, for example, in-line coating or off-line coating, so that the undercoat layer may be formed in the process. The problem of adhesion and deposition occurs. The deposits can sometimes fall off the film and degrade the quality of the film.

Further, Japanese Patent Publication No. 62-2986 discloses a method for forming a film comprising a crosslinkable silicone and a silane coupling agent. However,
As for the silicone film composed of a crosslinkable silicone and a silane coupling agent, in addition to the disadvantage that the silicone resin that can be used is limited due to the effect of the added silane coupling agent, the width of the design as a release film is reduced, When the adhesive strength with the base material is increased, there has been a difficulty in reducing the peeling force.

[0006] Also, Japanese Patent Application Laid-Open No. 5-25303 discloses that
The surface wetting index is changed to a certain range by corona treatment or the like on the polyester surface, and a thermosetting silicone resin layer is formed thereon, but the effect of improving the adhesion is still small.
Further, in order to improve the adhesion between the polyester film and the release layer, there is also a method using a non-silicone release layer such as silicone-modified urethane or acrylic resin,
In this case, the fact is that light releasability cannot be obtained.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a release film having excellent adhesion with time and releasability between a fine bubble-containing polyester film and a cured silicone resin coating film. is there.

[0008]

Means for Solving the Problems In view of the above-mentioned circumstances, the present inventors have made intensive studies on a release film having improved adhesiveness between a fine-bubble-containing polyester film and a silicone release layer and excellent release characteristics. As a result, they have found that this can be achieved by providing a specific primer layer on the fine-bubble-containing polyester film and forming a curable silicone resin coating film thereon, and have completed the present invention.

That is, the gist of the present invention is that a water-soluble or water-dispersible polyester resin, a water-soluble or water-dispersible polyurethane resin, a water-soluble or water-dispersible polyacrylate resin is formed on one side of a fine bubble-containing polyester film. Mold release comprising providing a primer layer coated with a coating agent containing at least one selected resin and at least one melamine-based or epoxy-based cross-linking agent, and providing a silicone release layer on the primer layer. Exist in film.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. In the present invention, the polyester is obtained by polycondensing an aromatic dicarboxylic acid and an aliphatic glycol. As the aromatic dicarboxylic acid, terephthalic acid, 2,
Examples of 6-naphthalenedicarboxylic acid include aliphatic glycols such as ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol. Representative polyesters include polyethylene terephthalate (PET) and polyethylene-2,6-
Naphthalenedicarboxylate (PEN) and the like are exemplified. Above all, polyethylene terephthalate (PET) is preferably used in terms of versatility, economy and the like. In the present invention, the polyester used may be a copolymerized polyester containing the third component in an amount of less than 20 mol%. Examples of the dicarboxylic acid component of the copolymerized polyester include isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, and oxycarboxylic acids (for example, P-oxybenzoic acid and the like). One or more kinds may be mentioned, and as the glycol component,
One or more of ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol and the like can be mentioned.

In the present invention, the fine-bubble-containing polyester film is not particularly limited as long as it is a polyester film containing fine bubbles. For example, a thermoplastic resin substantially incompatible with the above polyester is used. And a polyester film containing fine bubbles obtained by film-forming and stretching a polyester obtained by melting and dispersing a polyester.

Specific examples of the thermoplastic resin substantially incompatible with the above-mentioned polyester include polyolefins such as polypropylene, polyethylene, polymethylpentene and polymethylbutene, and thermoplastic resins such as polystyrene and polycarbonate. Is mentioned. Among these,
Polypropylene is practical in terms of cost and productivity.

The above-mentioned polypropylene is usually 95
Crystalline polypropylene whose propylene unit is at least mol% is used, and crystalline polypropylene whose propylene unit is at least 98 mol% is preferably used. Also, the melt flow index (MF) of the polypropylene used
Although I) is not particularly limited, it is usually 0.5 to 30 g / 1.
0 minutes, preferably in the range of 1 to 15 g / 10 minutes.

The content of the thermoplastic resin substantially incompatible with the polyester in the fine-bubble-containing polyester film is usually 5 to 45% by weight, preferably 5 to 45% by weight.
It is in the range of 35% by weight, more preferably 10-25% by weight. When the content is less than 5% by weight, the amount of bubbles formed in the film is small, so that the cushioning property is reduced, and the pressure-sensitive adhesive is laminated on the back surface of the release film or on the release layer side. When printing is performed on the surface of the base material by a thermal transfer method or the like, a clear image or the like may not be easily obtained. If the content exceeds 45% by weight, the film tends to be easily broken during film formation.

[0015] The density of the polyester film containing fine bubbles is usually 0.4 to 1.3 g / cm ³ , preferably 0.5 to 1.3 g / cm ³ .
5 to 1.2 g / cm ³ , more preferably 0.7 to 1.1
g / cm ³ . The density of the film is 0.4g /
If it is less than ³ cm ³ , rupture frequently occurs during film formation, so that productivity tends to deteriorate. If the density of the film exceeds 1.3 g / cm ³ , the cushioning property tends to be impaired.

It is preferable to blend a white pigment in the polyester film containing fine bubbles for the purpose of improving the concealing property, the print clarity and the like. The white pigment is not particularly limited, but titanium oxide fine particles are preferably used.
The average particle size of the white pigment is usually 0.05 to 1 μm, preferably 0.05 to 0.7 μm, more preferably 0.05 to 1 μm.
0.5 μm. The content of the white pigment is usually 0.5 to
It is 25% by weight, preferably 1 to 20% by weight, more preferably 2 to 20% by weight. When the content of the white pigment is less than 0.5% by weight, the concealing property is reduced, and the print clarity may be reduced. On the other hand, when the content exceeds 25% by weight, the film tends to be easily broken during film formation.

The method for containing the white pigment in the fine-bubble-containing polyester film is not particularly limited, but the raw material in which the white pigment is contained in the polyester raw material is used first, It is preferable to use them by blending them at an arbitrary ratio. The method for blending the white pigment with the polyester is not particularly limited, and a known method can be employed. For example, it can be added at any stage of producing the polyester, but is preferably added as a slurry dispersed in ethylene glycol or the like at the esterification stage or at the stage before the end of the transesterification reaction and before the start of the polycondensation reaction, The polycondensation reaction may proceed. Also, using a kneading extruder with a vent, a method of blending a slurry of a white pigment dispersed in ethylene glycol or water and a polyester raw material, or using a kneading extruder, drying a white pigment and a polyester raw material. It is performed by a blending method or the like.

In the present invention, the method of blending the incompatible thermoplastic resin with the polyester is not particularly limited, but the dried polyester raw material and the substantially incompatible polyester are incompatible with the polyester. It is performed by a method such as dry blending with a thermoplastic resin, and can be contained by supplying to an extruder. In the present invention, polyester or incompatible thermoplastic resin,
If necessary, additives such as a fluorescent whitening agent, an antioxidant, a heat stabilizer, a lubricant, an antistatic agent, a dye, and a pigment may be added.

The polyester film containing fine bubbles in the present invention can be produced according to the following known method. First, the raw material is melted by an extruder, and an unstretched sheet is obtained by extruding a sheet from a die onto a rotary cooling drum and solidifying by cooling, and then stretching the obtained unstretched sheet biaxially. Orient.

In the above-mentioned manufacturing method, in order to improve the adhesiveness between the unstretched sheet and the rotary cooling drum and to improve the flatness of the sheet, an electrostatic application adhesion method or a liquid application adhesion method is preferably employed. In the present invention, both may be used as needed. In the above manufacturing method, the stretching of the unstretched sheet can be performed, for example, as follows.
First, stretching is performed in one direction by a roll or tenter type stretching machine. The stretching temperature is usually from 70 to 120 ° C, preferably from 80 to 110 ° C, and the stretching ratio is usually from 2.5 to
It is 7 times, preferably 3.0 to 6 times. Next, stretching is performed in a direction orthogonal to the stretching direction of the first step. The stretching temperature is
The temperature is usually 70 to 120 ° C, preferably 80 to 115 ° C, and the stretching ratio is usually 3.0 to 7 times, preferably 3.5.
~ 6 times. Subsequently, heat treatment is performed at a temperature of 170 to 250 ° C. under tension or relaxation within 30% to obtain a biaxially stretched film.

Examples of the water-soluble or water-dispersible polyester resin used in the present invention include JP-B-47-40873.
JP-A-50-83497 and JP-A-50-83497.
Polyesters known in, for example, JP-A-121336 and JP-A-52-155640, and polyesters similar thereto can be used. For example, as the dicarboxylic acid component of the polyester, terephthalic acid, isophthalic acid, 2,5-naphthalenedicarboxylic acid and their ester-forming derivatives and the like are used as examples of aromatic dicarboxylic acids, and as examples of aliphatic dicarboxylic acids, Oxybenzoic acid and its ester-forming derivatives are used.

As the glycol component of the ester, aliphatic, alicyclic, aromatic diols and the like can be used. Examples thereof include ethylene glycol, 1,4-butanediol, diethylene glycol, triethylene glycol, 1,4- Cyclohexane dimethanol, p-xylene diol and the like are used, and poly (oxyalkylene)
Examples of the glycol include so-called polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like.

As the polyester, not only the saturated linear polyester comprising the above-mentioned ester-forming component but also 3
A polyester comprising a compound having an ester-forming component of a valency or lower or a polyester having a reactive unsaturated group can also be used. Examples of the water-soluble or water-dispersible polyurethane resin used in the present invention include:
JP-A-24194, JP-B-46-7720, JP-B-46-10193, and JP-B-49-37839.
JP, JP-A-50-123197, JP-A-50-123197
Known polyurethane resins such as those described in JP-A-126058 and JP-A-54-138098 can be used.

The main components of the polyurethane-forming component are a polyisocyanate, a polyol, a chain extender, a crosslinking agent and the like. Examples of polyisocyanates include tolylene diisocyanate, phenylene diisocyanate,
4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate and the like.

Examples of the polyol include polyethers such as polyoxyethylene glycol, polyoxypropylene glycol and polyoxytetramethylene glycol, polyesters such as polyethylene adipate, polyethylene-butylene adipate and polycaprolactone, and acrylic polyols. , Castor oil and the like. Examples of chain extenders or crosslinking agents include ethylene glycol, propylene glycol, butanediol, diethylene glycol, trimethylolpropane, hydrazine, ethylenediamine, diethylenetriamine, 4,
4'-diaminodiphenylmethane, 4,4'-diaminodicyclohexylmethane, water and the like.

The polyurethane resin has a molecular weight of 30.
A resin comprising a polyol having 0 to 20,000, a polyisocyanate, a chain extender having a reactive hydrogen atom, a group which reacts with an isocyanate group, and a compound having at least one anionic group is preferable. Anionic groups in the polyurethane-based _{resin, -SO 3 H, -OSO 3 H} ,
-It is used as a lithium salt such as COOH, a sodium salt, a potassium salt, or a magnesium salt. Of these, particularly preferred are sulfonate groups.

Examples of the water-soluble or water-dispersible polyacrylate resin used in the present invention include JP-A-2-3473, JP-A-2-292376, and JP-A-3-14.
3912, JP-A-3-20365, JP-A-63-223018, JP-A-62-212455
And polyacrylate resins known in JP-A-62-14191 and the like or polyacrylate resins similar thereto can be used.

As a method for producing a polyacrylate resin, for example, acrylate, methacrylic acid is obtained by transesterification or esterification of methyl alcohol, ethyl alcohol, butyl alcohol, 2-ethylhexyl alcohol or the like with methyl methacrylate or methacrylic acid. An ester is obtained, these acrylic monomers are appropriately selected, and polymerization is performed using a radical initiator such as a peroxide, an azo compound, or a redox system to obtain a polyacrylate resin. At this time, a hydrophilic group is introduced into the resin skeleton,
Hydrophilic resin. Among the acrylic monomers used for these, those having a functional group useful for a crosslinking reaction such as a hydroxyl group, a glycidyl group, a carboxyl group, an amino group, a silyl group, and a phosphoric acid group may be used.

Examples of the melamine crosslinking agent used in the present invention include alkylol or alkoxylated melamine compounds such as methoxymethylated melamine and butoxymethylated melamine, and urea is co-condensed with part of melamine. Can also be used. The epoxy crosslinking agent used in the present invention may be water-soluble or 50% water-soluble.
Any compound having the above epoxy group may be used.

The addition of the crosslinking agent improves the adhesion, water resistance, solvent resistance, and mechanical strength of the coating layer. As a result, after the application of the overcoat layer, the adhesion to the overcoat layer is improved. In particular, the melamine-based crosslinking agent has a high curing rate, and is more effective when used together with a curing catalyst such as a protonic acid or its ammonium salt. The amount of the curing agent used is preferably from 0.1 to 60% by weight based on the dry solid content of the coating film.

At least one resin selected from a water-soluble or water-dispersible polyester resin, a water-soluble or water-dispersible polyurethane resin, a water-soluble or water-dispersible polyacrylate resin, and a melamine or epoxy crosslinker Any known coating method can be applied as a method of applying a coating agent containing at least one of the above to the polyester film containing fine bubbles. For example, a rod coating method, a roll coating method, a gravure coating method, a roll brushing method, a spray coating method, an air knife coating method, an impregnation method, a curtain coating method, or the like can be applied alone or in combination.

It is preferable to select one of these methods as appropriate, and particularly to apply it to one or both surfaces of the fine bubble-containing polyester film before the completion of the crystal orientation. The fine-bubble-containing polyester film before the completion of the crystal orientation is defined as an unstretched film that has been extruded in the form of a sheet from a die of a melt extruder onto a rotary cooling drum and cooled and solidified, and the unstretched film is stretched in the longitudinal or transverse direction. And a biaxially stretched film that has been stretched in a direction perpendicular to the stretching direction of the uniaxially stretched film and has not been subjected to orientation crystallization by heat fixing. In particular, it is preferable that the coating liquid is applied to a uniaxially stretched film, and the coating liquid is dried while being guided by a tenter to horizontally stretch and thermally fix the fine bubble-containing polyester film.

The solid content of the above coating agent is usually 30% by weight or less, preferably 15% by weight or less. The coating amount is 0.5 to ²⁰ g / m ² , preferably 1 to 10 g / m ² . The coating agent for the microbubble-containing polyester film of the present invention, if necessary, a coating improver, a thickener, a lubricant, a polymer particle, an inorganic particle, a pigment, a dye, an antioxidant,
An ultraviolet absorber, an infrared absorber, an antistatic agent, an antifoaming agent, a foaming agent and the like can be contained. In addition, since the coating solution uses water as a medium, if necessary, gelatin,
Water-soluble resins such as polyvinyl alcohol and vinyl resins,
An emulsion such as an epoxy resin can be added to the coating solution before use.

In the present invention, it is necessary to provide a cured silicone resin coating on one of the surfaces of the polyester film containing fine bubbles on which the primer layer is provided. The cured silicone resin coating is a layer that imparts release properties to the film, and is formed by coating a coating liquid containing a curable silicone resin, drying and curing. The curable silicone resin is not particularly limited. For example, any of a condensation reaction type, an addition reaction type, an ultraviolet curing type, and an electron beam curing type can be used.

In the present invention, the curable silicone resin can be coated by a known method such as a reverse roll coating method, a gravure roll coating method, or an air knife coating method.
For example, the applied thermosetting silicone resin has a temperature of 50 ° C.
By performing a heat treatment at a temperature of 150 ° C., preferably 80 ° C. to 130 ° C. within 2 minutes, preferably 1 minute, a cured film can be formed.

The application amount of the curable silicone resin is as follows.
The range is preferably from 1 to 25 g / m ² , more preferably from ^{2 to 20} g / m ² , and the thickness of the cured silicone resin coating is 0.1 g / m ² .
The range is preferably from 01 to 1 μm, more preferably from 0.02 to 0.5 μm. When the thickness of the coating is less than 0.01 μm,
Release performance tends to decrease. The thickness of the coating is 1μ.
When it exceeds m, the curing of the coating film becomes insufficient, and the release performance may change with time.

[0037]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention. In the examples and comparative examples, “parts” means “parts by weight”. The measuring method used in the present invention is as follows. (1) Lab-off test After coating, place the sample in a room at 23 ° C / 50% RH.
After being left for 0 days, the coated surface was rubbed several times with a fingertip, and the degree of detachment of the cured silicone film was judged according to the following evaluation criteria and used as a measure of adhesion.

[0038]

[Table 1] ○: No detachment (good adhesion) △: Slight detachment, but no problem for practical use ×: Separation (poor adhesion) (2) Peeling force test On cured silicone resin coated surface of release film No. manufactured by Nitto Denko Corporation A 502 double-sided pressure-sensitive adhesive tape was adhered and pressure-bonded with a rubber roller at a linear pressure of 450 g / cm, and cut into a width of 50 mm to obtain a sample for peel force measurement. After leaving for 1 hour after the pressure bonding, the sample was peeled in a 180 ° direction at a tensile speed of 300 mm / min using an Instron type tensile tester, and the average value of the stress was taken as the peeling force of the sample. This test was repeated ten times, and the arithmetical average of ten times was defined as the peeling force. In addition,
The atmosphere in which this test was performed is a standard condition of 23 ° C./50% RH. <Polyester A for polyester film containing fine bubbles>
Production of dimethyl terephthalate 100 parts, ethylene glycol 60 parts and magnesium acetate tetrahydrate 0.0
Nine parts were placed in a reactor, heated and heated, and methanol was distilled off to carry out a transesterification reaction. The temperature was raised to 230 ° C. over 4 hours from the start of the reaction, and the transesterification reaction was substantially completed. Then, after adding 0.04 part of ethyl acid phosphate and 0.04 part of antimony trioxide, the temperature was set to 280 ° C. and the pressure was set to 15 mmHg in 100 minutes,
Thereafter, the pressure was gradually reduced to finally 0.3 mmHg. After 4 hours, the pressure in the system was returned to normal pressure to obtain a polyester. <Polyester B for polyester film containing fine bubbles>
Production of Polyester A (85 parts) and average particle size 0.27μ
m and 15 parts of titanium oxide particles were dry-blended and extruded using a twin-screw kneading extruder to obtain a polyester B. The content of titanium oxide in the polyester is 15% by weight.
Met. <Polyester C for polyester film containing fine bubbles>
Production> Polyester A 93 parts and average particle size 0.27μ
m and 7 parts of titanium oxide particles were dry-blended and extruded using a twin-screw kneading extruder to obtain a polyester C. The content of titanium oxide in the obtained polyester was 7% by weight. <Production of polyester resin> 33.7 parts of dimethyl terephthalate, 20.0 parts of dimethyl isophthalate, 3-
A mixture of 9.1 parts of sodiosulfodimethylisophthalate, 40 parts of ethylene glycol, 10 parts of diethylene glycol, and 0.047 parts of calcium acetate monohydrate was mixed with 200 to 2 parts.
The transesterification is carried out at 30 ° C. until the theoretical amount of methanol has distilled off.

Next, 0.09 part of orthophosphoric acid was added, and 0.025 part of antimony trioxide was further added.
The polymerization was carried out. The specific viscosity of the polymer thus obtained is
1.53. <Production of Polyurethane Resin> Polyether containing sulfonate group obtained by sulfonating polyether of ethylene oxide extracted from allyl alcohol with sodium metabisulfite (SO ₃ content: 8.3% by weight, polyethylene oxide content: 83% by weight) 192 parts, 1013 parts of polytetramethylene adipate (molecular weight: 2250), and 248 parts of polypropylene oxide polyether (molecular weight: 550) started with bisphenol A were mixed under vacuum,
Dehydrated at ℃. The mixture was heated to 70 ° C., and 178 parts of isophorone diisocyanate and hexamethylene-1,
A mixture with 244 parts of 6-diisocyanate was added, and the resulting mixture was then stirred at a temperature ranging from 80 ° C. to 90 ° C. until the isocyanate content was 5.6% by weight.

The prepolymer was cooled to 60 ° C., and 56 parts of biuret polyisocyanate obtained from 3 moles of hexamethylene diisocyanate and 1 mole of water, and 175 parts of bisketimine obtained from isophoronediamine and acetone were sequentially added. Water preheated to 50 ° C. in which 15 parts of hydrazine hydrate were dissolved was added to this mixture with vigorous stirring to obtain an aqueous polyurethane dispersion. <Production of polyacrylate resin> Ethyl acrylate 1
320 parts, 95 parts of acrylic acid, 9.5% of hydrogen peroxide based on the monomer, sodium octadecane sulfonate (14%)
%) About 20% of a low-temperature mixture of 30 parts and 1800 parts of water is first polymerized at 70 to 80 ° C. in a stirrer equipped with a condenser, and then 80% of the remaining liquid is gradually added over 2 to 3 hours. , 1
The polymerization was completed by stirring at 80 to 90 ° C. for 1.5 hours.
At this time, unreacted monomers were expelled while sending a nitrogen stream to obtain an emulsion. <Preparation of Coating Agent 1 for Primer Layer> 25 parts of a polyester resin, 65 parts of a polyurethane resin, and 10 parts of methoxymethylated melamine were weighed, and a 10% by weight aqueous dispersion was prepared. did. <Preparation of Primer Layer Coating Agent 2> 20 parts of a polyester-based resin, 70 parts of a polyacrylate-based resin, and 10 parts of methoxymethylated melamine were measured, and a 10% by weight aqueous dispersion was prepared. And <Preparation of coating agent 3 for primer layer> 20 parts of a polyester resin, 50 parts of a polyacrylate resin, 10 parts of methoxymethylated melamine, and 20 parts of a water-soluble epoxy cross-linking agent were weighed, and a 10% by weight aqueous dispersion was measured. Was adjusted to obtain a coating material 3 for a primer layer. <Preparation of Coating Agent 4 for Primer Layer> 50 parts of a polyester resin, 40 parts of a polyurethane resin, and 10 parts of a water-soluble epoxy cross-linking agent were measured, and a 10% by weight aqueous dispersion was prepared. And 4. <Preparation of coating agent 5 for primer layer> 25 parts of polyester resin, 65 parts of polyurethane resin, aziridine cross-linking agent Chemitite PZ-33 (trade name, manufactured by Nippon Shokubai Co., Ltd.) 1
0 parts were weighed out, and a 10% by weight aqueous dispersion was prepared to prepare a primer layer coating agent 5.

Example 1 83 parts of polyester B dried at 180 ° C. for 4 hours in an inert gas atmosphere were subjected to a melt flow index (MF)
I) A raw material obtained by dry-blending 17 g of crystalline polypropylene of 10 g / 10 min at 290 ° C. by a melt extruder.
And extruded, and cooled and solidified on a cooling roll having a surface temperature set to 40 ° C. using an electrostatic application adhesion method to obtain an unstretched sheet. The obtained sheet was stretched in the longitudinal direction by 3.4 times at 85 ° C. Next, the coating material 1 for a primer layer is applied on a uniaxially stretched film by a roll coating method, and then the film is guided to a tenter and stretched 3.2 times in a horizontal direction at 110 ° C., and then heat-set at 230 ° C. Thus, a 100 μm-thick microbubble-containing polyester film coated with a primer layer was obtained. Next, 100 parts by weight of a curable silicone resin (KS-779 manufactured by Shin-Etsu Chemical Co., Ltd.) and 1 part by weight of a curing agent (CAT PL-8 manufactured by Shin-Etsu Chemical Co., Ltd.) are applied on the polyester film containing fine bubbles coated with the primer layer. ,
Using a coating liquid consisting of 2,200 parts by weight of a methyl ethyl ketone / toluene mixed solvent, the coating thickness after curing by a roll coating method by off-line coating is 0.1 μm.
To obtain a release film having a cured silicone resin film formed thereon.

Example 2 A release film was obtained in the same manner as in Example 1 except that polyester B was changed to polyester C. Example 3 A release film was obtained in the same manner as in Example 1, except that the coating material 1 for the primer layer was changed to the coating material 2 for the primer layer.

Example 4 A release film was obtained in the same manner as in Example 1, except that the coating material 1 for the primer layer was changed to the coating material 3 for the primer layer. Example 5 A release film was obtained in the same manner as in Example 1 except that the coating material 1 for the primer layer was changed to the coating material 4 for the primer layer.

Example 6 A curable silicone resin (KS, manufactured by Shin-Etsu Chemical Co., Ltd.) was coated on a polyester film coated with the primer layer coating agent 1.
-723A) 100 parts by weight, (KS- manufactured by Shin-Etsu Chemical Co., Ltd.)
723B) 25 parts, curing agent (CAT manufactured by Shin-Etsu Chemical Co., Ltd.)
PS-3) A release film was obtained in the same manner as in Example 1, except that a coating solution consisting of 5 parts by weight and 2,200 parts by weight of a mixed solvent of methyl ethyl ketone / toluene was used.

Example 7 A curable silicone resin (X-manufactured by Shin-Etsu Chemical Co., Ltd.) was coated on a polyester film coated with the primer layer coating agent 1.
62-5039A) in the same manner as in Example 1 except that a coating solution consisting of 100 parts by weight, a curing agent (X-62-5039B manufactured by Shin-Etsu Chemical Co., Ltd.) 5 parts by weight, and a methyl ethyl ketone / toluene mixed solvent 2200 parts by weight was used. A release film was obtained.

Comparative Example 1 Polyester was dried at 180 ° C. for 4 hours in an inert gas atmosphere, and melt-extruded at 290 ° C. by a melt extruder.
An unstretched sheet was obtained by cooling and solidifying on a cooling roll having a surface temperature set to 40 ° C. by using an electrostatic application adhesion method. The obtained sheet was stretched 3.2 times in the longitudinal direction at 85 ° C. Next, the film was guided to a tenter, stretched 3.2 times in the transverse direction at 100 ° C., and then heat-set at 230 ° C.
A μm polyester film was obtained. A curable silicone resin (K manufactured by Shin-Etsu Chemical Co., Ltd.)
S-779) 100 parts by weight, a curing agent (CAT PL-8 manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part by weight, and a coating solution consisting of 2200 parts by weight of a mixed solvent of methyl ethyl ketone / toluene, and cured by roll coating by offline coating. Coating so that the subsequent coating thickness is 0.1 μm,
A release film on which a cured silicone resin film was formed was obtained.

The results obtained are summarized in Table 1 below.

[0048]

[Table 2] Comparative Examples 2 to 4 In Example 1, 100 parts of a polyester-based resin (Comparative Example 2), 100 parts of a polyurethane-based resin (Comparative Example 3), and a polyester-based resin 3 in place of the primer layer coating agent 1
A primer-coated microbubble-containing polyester film was obtained in the same manner as in Example 1, except that 10 parts by weight of an aqueous dispersion of 5 parts and 65 parts of a polyurethane resin (Comparative Example 4) were prepared and applied. In the obtained polyester film, the coating layer and the polyester film containing fine bubbles caused blocking, the coating layer was transferred to the polyester film containing fine bubbles, and did not reach the application of the curable silicone resin.

Comparative Example 5 A release film was prepared in the same manner as in Example 1 except that a 10% by weight aqueous dispersion of 100 parts of a polyacrylate resin was prepared and applied in place of the coating material 1 for the primer layer. I got The obtained film had a large variation in the peeling force and was non-uniform.

Comparative Example 6 A primer-coated polyester film containing fine bubbles was obtained in the same manner as in Example 1 except that coating material 1 for the primer layer was changed to coating material 5 for the primer layer. The primer layer of the obtained film was strongly agglomerated and the surface was in a roughened state. Next, Example 1
A release film was obtained in the same manner as described above, but the obtained film had a large variation in peeling force and was non-uniform.

[0051]

The release film of the present invention has excellent adhesion with time and release properties between the fine bubble-containing polyester film and the cured silicone resin coating film. It is extremely useful when used as a release film to be applied.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B32B 27/38 B32B 27/38 27/40 27/40 27/42 27/42

Claims (5)

[Claims] At least one kind selected from a water-soluble or water-dispersible polyester resin, a water-soluble or water-dispersible polyurethane resin, and a water-soluble or water-dispersible polyacrylate resin is provided on one surface of a fine bubble-containing polyester film. A release film comprising a primer layer coated with a coating agent containing a resin and at least one melamine-based or epoxy-based crosslinking agent, and a silicone release layer provided on the primer layer. 2. A polyester film containing microbubbles comprising a thermoplastic resin substantially incompatible with polyester.
-45% by weight and a density of 0.4-1.3 g /
The release film according to claim 1, which has a size of cm ³ . 3. The release film according to claim 2, wherein the thermoplastic resin substantially incompatible with the polyester is polypropylene. 4. The release film according to claim 1, wherein the polyester film containing fine bubbles contains 0.5 to 25% by weight of a white pigment. 5. The release film according to claim 4, wherein the white pigment is titanium oxide.