JP2000006349A - Release film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a release film capable of obtaining a uniform and flat surface in the molding of various resin sheets, resin coating films or ceramic sheets and extremely reduced in thermal deformation at the time of heat treatment. SOLUTION: This film contains naphthalene dicarboxylic acid as a main acid component and ethylene glycol as a main glycol component and also contains manganese, phosphorus and antimony elements originating from compds. of those elements in a ratio satisfying formulae: 0.7<=Mn<=1.6, 0.5<=Mn/P<=1.2 and 0.7<=Sb<=2.2 (wherein Mn is a molar number of a manganese element per an acid component 106 g, P is a molar ratio of a phosphorus element per an acid component 106 g and Sb is a molar ratio of an antimony element per an acid component 106 g.). Polyethylene naphthalate obtained by polycondensation is used as a base material film and the center line average roughness (Ra) of the surface thereof is set to 2-50 nm.

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 carrier film for producing a resin sheet or a resin coating formed from a resin solution, and a carrier film for forming a ceramic sheet formed from a ceramic slurry. The present invention relates to a release film having excellent thermal stability, flatness, and flatness, which is useful as a protective film for an adhesive layer such as an adhesive tape.

[0002]

2. Description of the Related Art A release film is used as a carrier film when forming a resin sheet, a resin coating, a ceramic sheet or the like.

[0003] A resin sheet is formed by coating (casting) a resin solution made of, for example, vinyl chloride on a carrier film, removing the solvent by heating, and separating and separating the carrier film. Used for applications.

[0004] A resin film is produced, for example, by applying a coating solution obtained by dissolving a resin serving as an adhesive in a solvent to the surface of a carrier film and then heating to remove the solvent.

A ceramic sheet is formed by, for example, applying a slurry in which a ceramic powder and a binder agent or the like are dispersed in a solvent to the surface of a carrier film, removing the solvent by heating, and peeling off the carrier film. .

[0006] In recent years, such resin sheets, resin coatings, ceramic sheets, and the like have been increasingly formed and manufactured using a release film. Above all, in applications requiring high performance such as electronic components and optical components, particularly in ceramic sheets and resin sheets, more uniform thickness and higher surface properties are required than ever before. In particular, ceramic sheets are often laminated when manufacturing a ceramic electronic component such as a capacitor. In order to increase the capacitance of the capacitor, the thickness of the ceramic sheet is reduced, and moreover, the number of laminated ceramic sheets is increasing.

[0007] Therefore, such a resin sheet, ceramic sheet, and the like must have a uniform thickness, a high precision, and a smoother surface. In order to manufacture such a sheet, not only the equipment for applying a coating solution such as a resin solution, an adhesive or a ceramic slurry requires a high-precision one, but also a carrier film for forming the sheet, a peeling method. Smoothness of the sheet surface of a resin sheet or the like obtained later, flatness without sagging or roll winding, dimensional stability after heat treatment, and workability in punching, cutting, and the like are required.

As the base film for the carrier film, various films such as an olefin film such as OPP and a biaxially oriented polyethylene terephthalate (hereinafter sometimes abbreviated as PET) film are used. For example, PET films are almost always
The surface is roughened by adding a filler or the like for the purpose of improving the winding property. Therefore, when a PET film having a particularly rough surface to which a filler is added is used as a carrier film, a molded resin sheet, a ceramic sheet, and the like, when a resin solution or the like is applied, pinholes are generated in some cases, A sheet with a uniform thin layer cannot be obtained, resulting in a product defect. Further, when laminating the formed sheets, there may be a problem that a void easily enters the lamination interface.

However, if the size and amount of the filler and the like are too limited, the surface roughness of the base film becomes too small,
In the take-up roll, the contact area between the films is increased, and peeling abnormality or the like occurs due to blocking, and the slippage is deteriorated. When the film is used in a process, a problem in transportability may occur.

Further, after the release film is coated with a resin solution or a ceramic slurry, it is subjected to a heat treatment for removing the solvent. The heating temperature is controlled by the glass transition temperature (Tg) of the base film used for the release film. ) Is often near or above, which causes thermal deformation such as dimensional changes and wrinkles in the release film, resulting in a problem that thickness unevenness and flatness of molded resin sheets are deteriorated and quality is deteriorated. is there.
In particular, when the heating temperature is increased in order to shorten the heat treatment time in order to improve the productivity of the resin sheets, there is a concern that the above-mentioned problem becomes more apparent.

In addition, the release film is often wound into a roll shape before applying the resin solution or the ceramic slurry. May occur. Thereby, there is a concern that the flatness of the coated resin sheet is impaired. Furthermore, depending on the film forming conditions, in the manufactured base film, internal stress remains, and when a resin solution or the like is applied, they are suddenly relaxed and locally sagging occurs, which is obtained by coating. There is a problem that the flatness of the resin sheet is impaired.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to overcome the disadvantages of the prior art and to obtain a uniform and flat surface in molding various resin sheets, resin coatings, ceramic sheets and the like. It is an object of the present invention to provide a release film having a very small thermal deformation during processing.

[0013]

According to the present invention, an object of the present invention is to provide a release film comprising a film comprising polyethylene naphthalate as a base film, wherein the polyethylene naphthalate is mainly composed of naphthalenedicarboxylic acid. As an acid component, ethylene glycol is used as a main glycol component, and manganese, phosphorus and antimony elements derived from a manganese compound, a phosphorus compound and an antimony compound are contained in proportions simultaneously satisfying the following formulas (1) to (3), and polycondensation is carried out. And a center film having a center line average roughness (Ra) of 2 to 50 nm. 0.7 ≦ Mn ≦ 1.6 (1) 0.5 ≦ Mn / P ≦ 1.2 (2) 0.7 ≦ Sb ≦ 2.2 (3) Where Mn is the number of moles of manganese element per 10 ⁶ g of acid component, P is the number of moles of phosphorus element per 10 ⁶ g of acid component, and Sb is the number of moles of antimony element per 10 ⁶ g of acid component.)

Hereinafter, the present invention will be described in detail. As the base film in the present invention, a polyethylene naphthalate film is used, and as a polymer constituting the film,
Polyethylene naphthalate (hereinafter sometimes abbreviated as PEN) obtained by polycondensation using naphthalenedicarboxylic acid as a main acid component and ethylene glycol as a main glycol component.

Examples of the naphthalenedicarboxylic acid include 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, and 1,5-naphthalenedicarboxylic acid. Dicarboxylic acids are preferred.

If the main acid component is not naphthalenedicarboxylic acid, for example, it is unfavorably formed into a film, and the resulting curl remains, and the flatness of the film is impaired.

Such a PEN polymer can be used, for example, in the range of not impairing the heat deformation resistance of the release film, for example, aromatic dicarboxylic acids (terephthalic acid, isophthalic acid, diphenylethanedicarboxylic acid, diphenyldicarboxylic acid, diphenyletherdicarboxylic acid, diphenylsulfonedicarboxylic acid). , Diphenyl ketone dicarboxylic acid, anthracene dicarboxylic acid, etc.), aliphatic dicarboxylic acid (adipic acid, succinic acid, sebacic acid, dodecane dicarboxylic acid, etc.), alicyclic dicarboxylic acid (cyclohexane-1,4-dicarboxylic acid, 1,3) Components such as adamantane dicarboxylic acid) and aliphatic oxyacids (hydroxybenzoic acid oxyacid, ω-hydroxycaproic acid, etc.) in an amount of 2 to the total amount of all acid components.
It can be copolymerized or bonded at 0 mol% or less.

As glycol components other than ethylene glycol constituting the PEN film, aliphatic glycols (for example, those having 3 to 10 carbon atoms such as trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, and decamethylene glycol) are used.
Polymethylene glycol, cyclohexanedimethanol, etc.), aromatic diols (eg, hydroquinone, resorcin, 2,2-bis (4-hydroxyphenyl) propane, etc.), poly (oxy) alkylene glycols (eg, polyethylene glycol, polytetramethylene glycol) Etc.), but the proportion of these other glycol components is preferably 20 mol% or less based on the total glycol components.

The PEN polymer may contain a glycol component other than ethylene glycol such as glycerin, pentaerythritol, trimellitic acid, pyromellitic acid or the like, as long as the thermal deformation resistance of the release film is not impaired. The compound having the compound may be copolymerized in an extremely small amount as long as a substantially linear polymer can be obtained and as long as the effects of the present invention are not impaired.

Further, in order to improve the hydrolysis resistance of the PEN polymer, part or all of the terminal hydroxyl groups and / or carboxyl groups are blocked with a monofunctional compound such as benzoic acid or methoxypolyalkylene glycol. May be done.

The PEN film in the present invention can be produced by a conventional polyester production method, but is preferably produced by a transesterification method, that is, by reacting a lower alkyl ester of naphthalenedicarboxylic acid with ethylene glycol. . Examples of the lower alkyl ester of naphthalenedicarboxylic acid include, for example, dimethyl ester, diethyl ester, dipropyl ester and the like, with dimethyl ester being particularly preferred.

The PEN polymer used in the present invention preferably has an intrinsic viscosity of 0.40 to 0.90 dl / g measured at 35 ° C. in an o-chlorophenol solution, particularly preferably 0.50 to 0.90 dl / g. It is preferably in the range of 0.85 dl / g. When the intrinsic viscosity is within the above range, a polyester film having excellent heat resistance can be easily obtained, and the molten P
The extrudability and film-forming properties of the EN polymer are improved.

The PEN polymer of the present invention has a mean particle size of 0.01 in order to impart slipperiness and improve film winding property within a range not impairing its effect.
Inorganic fine particles or organic fine particles having a thickness of from 20 to 20 μm, preferably from 0.1 to 5 μm can be added.

The ratio of the fine particles is such that the center line average roughness (Ra) of the substrate film surface is in the range of 2 to 50 nm,
For example, the content is preferably 0.001 to 10% by weight, particularly preferably 0.01 to 3% by weight.

Specific examples of such fine particles include silicon dioxide, anhydrous silicon, hydrated silicon, aluminum oxide, kaolin, calcium carbonate, titanium oxide, aluminum silicate (including calcined products and hydrates), lithium benzoate, and sulfuric acid. Barium, double salts of these compounds (including hydrates),
Preferred examples include inorganic fine particles such as carbon black, glass powder, and clay (including kaolin, benite, and clay), and organic fine particles such as a crosslinked acrylic resin, a crosslinked polystyrene resin, a melamine resin, a crosslinked silicone resin, and a polyamideimide resin. it can.

In order to maintain the effects of the present invention, it is preferable to use inert particles in order to prevent a change in performance due to interaction. In addition, one kind of these fine particles may be used, or two or more kinds may be used. PEN polymer is PE
Since the molecular chain is rigid and the stiffness of the film is higher than that of the T polymer, even if the blending amount of the fine particles is smaller than that of the PET polymer, the sliding property is good and sufficient winding property can be obtained.

As a method for containing the fine particles, a method of thinly laminating a layer containing these fine particles on at least one surface of the substrate film can also be used.
Examples of the laminating method include coating at the time of film formation, and a co-extrusion method using a plurality of extruders and a feed block or a multi-manifold die.

In addition to the fine particles, a stabilizer, an ultraviolet absorber, a coloring agent, a flame retardant, an antistatic agent, a light stabilizer, an antioxidant, etc. may be used as long as the surface flatness and thermal stability of the film are not impaired. Can be incorporated into the PEN polymer. Further, other thermoplastic resin may be added in a small amount (for example, 20% by weight or less, particularly 10% by weight or less).

In the production of the PEN polymer of the present invention, a manganese compound, preferably a manganese compound soluble in the reaction system, is added to naphthalene dicarboxylic acid, preferably a lower alkyl ester thereof, and ethylene glycol as a transesterification catalyst to form an ester. Perform an exchange reaction.

The manganese compound is added in such an amount that the manganese element amount becomes 0.7 to 1.6 mol (hereinafter, the unit of the addition amount is abbreviated to mol element / ton) based on 10 ⁶ g of the total acid component. . Such an addition amount is preferably in the range of 1.0 to 1.5 mol element / ton.

If the addition amount of the manganese compound exceeds 1.6 mol element / ton, the catalyst residue may affect the precipitated particles,
When the film is formed, the surface flatness is deteriorated, and as a result, the transparency of the film may be poor. Also, when a release layer is provided on the film, particularly, an addition-reaction type silicone resin is applied. In this case, the catalyst becomes a poison for the curing of the silicone, and the curing of the silicone may be insufficient. On the other hand, when the addition amount is less than 0.7 mol element / ton, not only the transesterification reaction becomes insufficient, but also the subsequent polymerization reaction becomes slow, which is not preferable.

The manganese compound used in the present invention is not particularly limited, but is preferably an oxide, chloride, carbonate, carboxylate or the like, and particularly preferably an acetate, that is, manganese acetate.

In the production of the PEN polymer of the present invention, when the transesterification is substantially completed, a phosphorus compound is added to deactivate a part of the transesterification catalyst.

The molar ratio (Mn / Mn) of the amount of the transesterification catalyst, ie, the manganese compound, added to the phosphorus compound.
P) needs to be 0.5 to 1.2, preferably 0.6 to 1.1. When the molar ratio is less than 0.5, the surface flatness is deteriorated when a film is formed due to the influence of precipitated particles due to catalyst residues, and when a release layer is provided on the film, particularly, When an addition reaction type silicone resin or the like is applied, it becomes a catalyst poison for the curing of silicone, and there is a concern that the curing of silicone becomes insufficient. On the other hand, when the molar ratio exceeds 1.2, the thermal stability of the PEN polymer deteriorates due to the activity of the manganese compound that is not sufficiently deactivated by the phosphorus compound, and the hue becomes poor when formed into a film, It is not preferable because the flatness deteriorates.

The phosphorus compounds used in the present invention include trimethyl phosphate, triethyl phosphate, tri-
n-butyl phosphate, phosphoric acid and the like. Particularly preferred is trimethyl phosphate.

In the production of the PEN polymer according to the present invention, after adding the phosphorus compound, the reaction product is subjected to a polycondensation reaction to obtain a PEN polymer.

At this time, an antimony compound is added to the reaction product as a main catalyst of the polycondensation reaction. The antimony compound may be added before the start of the transesterification reaction.

The amount of the antimony compound added is 0.7 to
It must be in the range of 2.2 mole elements / ton.
If the addition amount is less than 0.7 mol element / ton, the polycondensation reactivity becomes poor and the productivity becomes poor, which is not preferable. On the other hand,
When the addition amount is more than 2.2 mol element / ton, when the film is formed for a long time, a precipitate originating in the antimony compound is generated to cause a film defect, or when a release layer is provided on the film. In particular, when an addition reaction type silicone resin or the like is applied, it becomes a catalyst poison for the curing of the silicone, and the curing of the silicone becomes insufficient.

The antimony compound used in the present invention is preferably an oxide, chloride, carbonate, carboxylate or the like. In particular, when acetate, ie, antimony acetate, is used, the precipitated particles in the polymer are smaller than those of other compounds. This is preferable because the film transparency is improved.

Such a PEN polymer film is not particularly limited by its manufacturing method, and can be manufactured by a known method. For example, an example of a manufacturing method will be described below.

The biaxially oriented PEN film in the present invention can be produced by a conventionally known method such as a sequential biaxial stretching method or a simultaneous biaxial stretching method. For example, in the sequential biaxial stretching method, a PEN polymer is sufficiently dried, and then an unstretched film is produced by a melt extrusion method at a temperature of Tm to (Tm + 70) ° C. (Tm; melting point of the PEN polymer). The unstretched film is treated with (Tg-10) to (Tg
+50) ° C (Tg; glass transition temperature of PEN polymer)
At a temperature of 2 to 6 times in the film roll winding direction,
Next, stretching is performed 2 to 6 times in the vertical direction at a temperature of Tg to (Tg + 50) ° C., and further, (Tg + 60) to (Tg).
(+140) ° C. for 5 seconds to 1 minute. The heat setting may be performed under tension or limited shrinkage. At the time of melt extrusion, it is preferable to use an electrostatic adhesion method. Further, the stretching conditions in the winding direction and the vertical direction are determined by the biaxially oriented PE obtained.
It is preferable to select conditions so that the physical properties of the N film are substantially equal in the longitudinal direction and the width direction.

At the heat setting temperature, (Tg + 60) ° C.
If it is lower than this, there is a concern that, when stored in a rolled state with a film, a curl may sometimes remain or delamination may occur inside the film. On the other hand (Tg + 140)
If the temperature is higher than ℃, whitening occurs due to excessive film crystallization, resulting in insufficient transparency and mechanical strength.

In the case of simultaneous biaxial stretching, the stretching temperature, stretching ratio, heat setting temperature and the like of the above sequential biaxial stretching can be applied.

The base film has an elastic modulus of 1.0 × 1 in both the winding direction of the film roll and the vertical direction.
It is preferably in the range of 0 ^{11 to} 1.7 × 10 ¹¹ dyne / cm ² . The elastic modulus is 1.0 × 10 ¹¹ dyne / cm
^{If it is} smaller than ² , burrs, warpage, and the like are likely to occur in punching such as cutting. If it is larger than 1.7 × 10 ¹¹ dyne / cm ² , the cutting proceeds more than necessary at the time of cutting, and it is difficult to perform predetermined cutting.

The base film of the present invention preferably has a film density of 1.360 to 1.370 g / cm ³ . When the density of the film is less than 1.360 g / cm ³ , molecules oriented by stretching do not grow into sufficient crystals and are inferior in dimensional stability.
The absolute value of the heat shrinkage after the treatment for 10 minutes exceeds 1.0% in at least one direction, which is not good. In addition, 1.370 g
If it exceeds / cm ³ , the film becomes brittle due to crystallization, and the impact resistance is poor.

Further, the base film of the present invention has a center line average roughness (Ra) of the film surface of 2 to 50 nm, particularly preferably 6 to 40 nm. When the center line average roughness (Ra) is less than 2 nm, the slipperiness of the film is deteriorated and the winding property is deteriorated. When it exceeds 50 nm, the surface roughness of the film becomes too large. The surface of a resin sheet or the like cast and formed thereon becomes rough, and a smooth surface cannot be obtained.

The thickness of the substrate film used in the present invention is not particularly limited, but is preferably from 5 to 500 μm, particularly preferably from 10 to 200 μm.

In the present invention, it is preferable to provide a release layer on at least one side of the base film. Examples of the components that form the release layer include silicone resins, fluororesins, and waxes such as aliphatics. Further, a release layer may not be provided depending on the resin to be cast.

The components forming such a release layer may be blended with various known additives within a range not to impair the object of the present invention. Examples of the additive include an ultraviolet absorber, a pigment, an antifoaming agent, and an antistatic agent.

The release layer can be applied by applying a coating liquid containing a component forming the release layer to a base film and drying by heating to form a coating film. The heating conditions are 80 to 160 ° C. for 10 to 120 seconds, particularly 120
It is preferably at a temperature of 150 ° C. for 20 to 60 seconds. The application method is
Any known method can be used, and examples thereof include a roll coater method and a blade coater method.

In the present invention, it is preferable to provide an adhesive layer between the base film and the release layer in order to enhance the adhesion between the base film and the release layer. As a component forming the adhesive layer, for example, when the release layer is a silicone resin layer, a silane coupling agent is preferable. Those represented by the general formula Y-Si-X ₃ is more preferred as the silane coupling agent. Here, Y represents a functional group represented by, for example, an amino group, an epoxy group, a vinyl group, a methacryl group, a mercapto group, and X represents a hydrolyzable functional group represented by an alkoxy group. The thickness of the adhesive layer is 0.0
The range is preferably from 1 to 5 μm, and particularly preferably from 0.02 to 2 μm. When the thickness of the adhesive layer is within the above range, the adhesion between the base film and the release layer becomes good, and the base film provided with the adhesive layer is difficult to block, so that problems in handling the release film are unlikely to occur. There are advantages.

[0052]

The present invention will be further described below with reference to examples. In addition, each characteristic value was measured by the following method. 1. Glass transition temperature (Tg) Differential calorimeter (Du Pont DSC2100)
The glass transition peak temperature is determined at a heating rate of 20 ° C./min.

2. Center line average roughness (Ra) Using a stylus type surface roughness meter (Surfcoder 30C, manufactured by Kosaka Laboratory Co., Ltd.), the film surface is scanned under the conditions of a needle radius of 2 μm and a stylus pressure of 30 mg, The displacement of the film surface was measured and the surface roughness curve was recorded. The cut-off value is 80 μm. From this surface roughness curve, the measured length (L) is extracted in the direction of the center line, and the surface roughness curve (Y = f) when the X axis is the scan distance and the Y axis is the surface displacement
(X)) was calculated by the following equation.

[0054]

(Equation 1)

3. Intrinsic viscosity Measured in an o-chlorophenol solution at 35 ° C.

4. Thermal Stability of Base Film The thermal degradation index was determined from the intrinsic viscosity of the polymer before and after the preparation of the base film using the following equation, and the thermal stability of the PEN polymer was evaluated. Thermal degradation index = ([ηo] / [ηx])-1 where [ηo]: intrinsic viscosity of polymer before film formation [ηx]: intrinsic viscosity of polymer of film after film formation <criterion for determining thermal stability > ○: Thermal degradation index ≦ 0.05 △: 0.05 <Thermal degradation index ≦ 0.10 ×: 0.10 <Thermal degradation index

5. Flatness of release film The addition reaction type silicone is applied as a release layer to the base film, and the film is heated at 140 ° C. for 1 minute. The film is cut into a size of 10 cm × 20 cm, and is a free-length flat floor. Place on the surface, 10cm × 10c of the film
The portion m was covered with a metal plate, and the lifting of the edge of the uncovered film was observed and evaluated according to the following criteria. <Judgment Criteria> ：: Height of edge floating is less than 2 mm Δ: Height of edge floating is 2 mm or more and less than 8 mm ×: Height of edge floating is 8 mm or more

6. Processability A polyvinyl alcohol resin dissolved in water as a model paint is dried on the release film having a thickness of 30%.
It was applied to a thickness of μm, and the water was dried and evaporated. afterwards,
Using a metal mold of 15 cm square, the occurrence of burrs and corners of punched edges and the occurrence of cracks were observed, and evaluated according to the following criteria. ：: No burr or bending occurs. Δ: Fine burrs are generated or the film is bent, and the resin film is slightly elongated. Alternatively, minute delamination occurs. ×: A state in which delamination, burrs, or cracks occur in the release film, or the resin film cannot be cut sufficiently.

Example 1 To 100 parts by weight of 2,6-naphthalenedicarboxylic acid dimethyl ester and 60 parts by weight of ethylene glycol, manganese acetate tetrahydrate was added as a transesterification catalyst in an amount shown in Table 1, and transesterification was carried out. After that, trimethyl phosphate was added in the amount shown in Table 1 to terminate the transesterification reaction. Further, after adding antimony trioxide in the amount shown in Table 1, a polycondensation reaction was subsequently performed under a high temperature and a high vacuum to obtain a PEN polymer having an intrinsic viscosity of 0.62.

Next, the PEN polymer was melted by an extruder containing 0.15% by weight of spherical silica particles having an average particle diameter of 0.3 μm, and was placed on a rotary cooling drum maintained at 40 ° C. from a die. The molten polymer was extruded and brought into close contact with a rotary cooling drum using an electrostatic adhesion method, and was rapidly cooled to obtain an unstretched film. Next, the unstretched film is moved in the longitudinal direction by 3.6.
And then stretched 3.6 times in the transverse direction, and then 230 ° C.
To obtain a biaxially oriented PEN film having a thickness of 50 μm.

On one surface of the biaxially oriented PEN film, a coating solution prepared by the method described below was applied at a coating amount of 6 g / m ² (wet), and heated and dried at a temperature of 140 ° C. for 1 minute, followed by curing. A release film having a release layer thickness of 0.1 μm was prepared. Table 1 shows the characteristics of the release film.

The coating liquid is prepared by dissolving an addition-reaction-type curable silicone composed of polydimethylsiloxane having a vinyl group and dimethylhydrogensilane in a mixed solvent of methyl ethyl ketone, methyl isobutyl ketone and toluene, and further dissolving the silicone resin. A solution having a solid content ratio of 2% was added to the curable silicone so as to have a solid content ratio of 10% by weight, and a platinum catalyst was added to this solution to prepare a solution.

Example 2, Comparative Examples 1-2 The amounts of manganese acetate, trimethyl phosphate and antimony trioxide were changed as shown in Table 1, and the content of spherical silica particles was further reduced to 0.40% by weight. A release film was obtained in the same manner as in Example 1 except for changing to. Table 1 shows the characteristics of the release film.

[0064]

[Table 1]

As is clear from Table 1, the release films of the present invention shown in the examples have excellent heat stability as a base film, and have dimensional stability after heat treatment when a release layer is provided. Excellent in workability and flatness, and good in workability. In addition, the release films of Comparative Examples 1 and 2 are inferior in thermal stability of the formed film, and thus have poor flatness and transparency, and further have poor flatness when formed into a release film. The thickness of the applied resin solution was poor, and delamination occurred during cutting, which was insufficient.

[0066]

According to the present invention, the thermal stability is good, the flatness as a release film is excellent, the deformation due to heat during molding of a resin sheet is very small, and the workability such as cutting accuracy is high. A release film for producing sheets having excellent properties can be provided.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F071 AA45 AB05 AB06 AB26 AD02 AF19 AF27 AF45 AG28 AH19 BA01 BB06 BB08 BC01 BC02 BC10 BC16 4F100 AA20H AJ11B AJ11C AK17B AK17C AK41A AK52B AK52CBA02 BA03 BA01 BA10 BA01 BA10 EJ38A GB90 JB12B JB12C JJ03 JK15 JL01 4J002 BD122 CF081 CP032 DD076 DD078 DE096 DE128 DE246 DE248 EG056 EG058 EW047 GF00

Claims (4)

[Claims] 1. A release film comprising a film made of polyethylene naphthalate as a base film, wherein said polyethylene naphthalate contains naphthalenedicarboxylic acid as a main acid component, ethylene glycol as a main glycol component, a manganese compound, phosphorus It contains manganese, phosphorus and antimony elements derived from a compound and an antimony compound at a ratio satisfying the following formulas (1) to (3) at the same time, and is obtained by polycondensation. A release film having a linear average roughness (Ra) of 2 to 50 nm. 0.7 ≦ Mn ≦ 1.6 (1) 0.5 ≦ Mn / P ≦ 1.2 (2) 0.7 ≦ Sb ≦ 2.2 (3) Where Mn is the number of moles of manganese element per 10 ⁶ g of acid component, P is the number of moles of phosphorus element per 10 ⁶ g of acid component, and Sb is the number of moles of antimony element per 10 ⁶ g of acid component.) 2. The release film according to claim 1, wherein the polyethylene naphthalate is polyethylene-2,6-naphthalate produced by a transesterification method. 3. The heat setting of the substrate film after the biaxial stretching is performed at (Tg + 60) to (Tg + 140) ° C. (where Tg represents the glass transition temperature of polyethylene naphthalate).
The release film according to claim 1, wherein the release film is a film performed at a temperature of 3. 4. The release film according to claim 1, wherein at least one selected from a silicone resin, a fluororesin and an aliphatic wax is laminated on at least one surface of the base film.