JPH10138430A - Release film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a release film which does not roughen a surface of a resin sheet, a ceramic sheet or the like when the release film is peeled therefrom, and which causes no thermal deformation at the time of heating treatment, in a release film to be used when a resin sheet, a ceramic sheet or the like is molded. SOLUTION: In this release film, a base film is a biaxially orientated polyethylene-2,6-naphthalenedicarboxylate film whose surface roughness Ra is less than 10nm. An absolute value of the rate of dimensional change under the stress of 150gf/mm<2> at 120 deg.C is at most 0.2% both in the direction of stress and in its perpendicular direction.

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 molding such as a resin sheet or a resin coating formed from a resin solution, a ceramic sheet formed from a ceramic slurry, or an adhesive tape. And a release film useful as a protective film for the pressure-sensitive adhesive layer.

[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. Provided for use.

[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. .

Generally, among the surfaces of resin sheets, ceramic sheets, and the like, the surface peeled from the carrier film is often used for applications requiring high-accuracy surface properties. The surface roughness of the base film used largely determines the surface roughness of a resin sheet, a ceramic sheet, or the like.

Various films, particularly biaxially oriented polyethylene terephthalate (hereinafter sometimes abbreviated as PET) films, are used as the base film of these carrier films. The surface is roughened by adding a filler or the like for the purpose of improving the properties. Therefore, PE with filler added
The surface of a resin sheet or ceramic sheet molded with a carrier film using a T film as a base film is roughened, and when laminating the sheets with each other, there is a problem that a gap is easily formed in a lamination interface. There is.

On the other hand, the release film is coated with a resin solution or a ceramic slurry and then heated to remove the solvent. The heating temperature is set to the glass transition temperature (Tg) of the base film used for the release film. In many cases, it is close to or more than that, which causes thermal deformation such as dimensional change or wrinkles in the release film, and there is a problem that thickness unevenness and flatness of molded resin sheets are deteriorated and quality is deteriorated. . In particular, when the heat treatment time is shortened and the heating temperature is increased in order to improve the productivity of resin sheets and the like, there is a concern that the above-mentioned problem becomes more apparent.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art and to prevent the surface of various resin sheets, resin coatings, ceramic sheets, etc. from being roughened, and to reduce thermal deformation during heat treatment. It is to provide a release film which does not occur.

[0010]

According to the present invention, there is provided a release film wherein the base film is a biaxially oriented polyethylene-2,6-naphthalenedicarboxylate film having a surface roughness Ra of less than 10 nm, wherein 150 in
A release film characterized in that the absolute value of the dimensional change rate under a gf / mm ² stress is 0.2% or less in both the stress direction and the vertical direction.

The surface roughness Ra is a surface roughness curve (Y = f (x) obtained using a stylus type surface roughness meter, where Y: surface displacement, X: scan distance, surface Average length of displacement: Y = 0), measured length (L) in the direction of the center line
Is given by the following equation.

[0012]

(Equation 1)

The absolute value of the dimensional change rate is 30 m in length.
m, a strip-shaped release film cut into a width of 4 mm is mounted on a TMA (thermal stress strain measurement device) so that the distance between the chucks is 10 mm, and a stress of 150 gf / mm ² is measured in a direction in which a dimensional change rate is measured. Then, the temperature is increased from room temperature at a rate of 5 ° C./min, and the dimensional change when the temperature reaches 120 ° C. is measured in the stress direction (longitudinal direction of the release film) and vertically (in the width direction of the release film). It was obtained by the following equation.

[0014]

## EQU2 ## Absolute value of dimensional change rate = │dimensional change / distance between chucks│ × 100

As the base film in the present invention,
A biaxially oriented polyethylene-2,6-naphthalenedicarboxylate film is used. The polyethylene-2,6-naphthalenedicarboxylate (hereinafter sometimes abbreviated as PEN) constituting this film is ethylene-
Polyester containing 2,6-naphthalenedicarboxylate as a main repeating unit.

In such a PEN polymer, a small amount of copolymer component (10
Mol% or less, especially 5 mol% or less).

Examples of the copolymerization component include terephthalic acid, isophthalic acid, phthalic acid, and naphthalene-2,7.
-Dicarboxylic acid, 4,4'-diphenyldicarboxylic acid,
Aromatic dicarboxylic acids such as 4,4'-diphenyl ether dicarboxylic acid; aliphatic dicarboxylic acids such as oxalic acid and adipic acid; oxycarboxylic acids such as p-oxybenzoic acid and p-oxyethoxybenzoic acid; diethylene glycol; Preferred are glycols such as -propylene glycol, 1,4-tetramethylene glycol, 1,6-hexamethylene glycol, neopentyl glycol and the like.

The PEN polymer is obtained by copolymerizing a compound having three or more functional groups such as glycerin, pentaerythritol, trimellitic acid, and pyromellitic acid within a range where a substantially linear polymer can be obtained. You may.

Furthermore, 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. It may be something.

The PEN polymer used in the present invention is a homopolymer having an intrinsic viscosity of 0.5 or more and having only ethylene-2,6-naphthalenedicarboxylate as a repeating unit. This is preferred because a base film having excellent thermal characteristics such as thermal characteristics and heat deformation resistance can be obtained.

Such a 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. In the case of a PEN copolymer, it can be produced by adding a copolymer component to the above-mentioned polymer component and subjecting it to polycondensation.
It can also be produced by mixing an N polymer in a molten state and performing a transesterification reaction.

The PEN polymer has an average particle diameter of 0.01 to 0.01 in order to improve the film winding property.
A ratio of the inorganic fine particles or organic fine particles of 20 μm in which the surface roughness Ra of the film is less than 10 nm, for example, 0.
It is preferable to contain 005 to 2% by weight. Specific examples of such fine particles preferably include inorganic fine particles such as silica, alumina, kaolin, calcium carbonate, titanium oxide, barium sulfate, and carbon black, and organic fine particles such as a crosslinked acrylic resin, a crosslinked polystyrene resin, a melamine resin, and a crosslinked silicone resin. be able to. Since the molecular chain of the PEN polymer is rigid and the stiffness of the film is higher than that of the PET polymer, sufficient winding properties can be obtained even if the amount of the fine particles is smaller than that of the PET polymer.

In addition to the fine particles, additives such as a stabilizer, an ultraviolet absorber, a flame retardant, and an antistatic agent can be blended. A small amount of other thermoplastic resin (for example, 20% by weight)
Below, especially 10% by weight or less).

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. Subsequently, the unstretched film is stretched at a temperature of 130 to 150 ° C. in the longitudinal direction by 2 to 6 times. And then stretched in the transverse direction at a temperature of 120-150 ° C.
It can be manufactured by performing 6-fold stretching and heat-setting at a temperature of 220 to 255 ° C. for 5 seconds to 1 minute.
The heat setting may be performed under limited shrinkage. At the time of melt extrusion, it is preferable to use an electrostatic adhesion method.

Further, in order to improve the isotropy of the PEN film, it is preferable to make the above-mentioned stretching ratios in the longitudinal and transverse directions the same. In order to further improve the thermal deformation resistance of the release film at around 110 ° C., it is preferable to heat-treat the biaxially stretched and heat-set film at a temperature of 120 to 150 ° C. in a relaxed state.

The thickness of the biaxially oriented PEN film used in the present invention is not particularly limited, but is preferably from 10 to 200 μm.

In the present invention, it is preferable to provide a release layer on at least one surface of the biaxially oriented PEN film.
Examples of the component forming the release layer include a silicone resin, a fluororesin, and an aliphatic wax. Further, a release layer may not be provided depending on the resin to be cast.

Various known additives can be added to the components forming the release layer as long as the objects of the present invention are not hindered. Examples of the additive include an ultraviolet absorber, a pigment, and an antifoaming agent.

The release layer can be applied by applying a coating liquid containing a component forming the release layer to a biaxially oriented PEN film, and drying by heating to form a coating film.
The heating conditions are 80 to 160 ° C. for 10 to 120 seconds,
In particular, it is preferably at 120 to 150 ° C. for 20 to 60 seconds. As the coating method, 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 preferably in the range of 0.01 to 5 μm, and
The range of μm is particularly preferred. When the thickness of the adhesive layer is in 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 there is an advantage that a problem does not easily occur in handling the release film. is there.

[0031]

The present invention will be further described below with reference to examples. In addition, each characteristic value was measured by the following method.

(1) Surface Roughness (Ra) Using a stylus type surface roughness meter (Surfcoder 30C, manufactured by Kosaka Laboratories Co., Ltd.), the film surface was measured under the conditions of a needle radius of 2 μm and a stylus pressure of 30 mg. Scanning, the displacement of the film surface was measured, and the surface roughness curve was recorded. From this surface roughness curve, the measured length (L) is extracted in the direction of the center line, and from the surface roughness curve (Y = f (x)) when the X axis is the scan distance and the Y axis is the surface displacement. It was calculated by the following equation.

[0033]

(Equation 3)

(2) Thermal Deformation Resistance (Absolute Value of Dimensional Change) A rectangular film cut in a measuring direction at a width of 30 mm or more and a width of 4 mm was subjected to TMA (thermal stress / strain measuring apparatus, TMA / SS120C manufactured by Seiko Denshi Kogyo KK). )) So that the distance between the chucks is 10 mm.
Apply a stress of 0 gf / mm ² , heat from room temperature at a rate of 5 ° C./min, measure the dimensional change when reaching 120 ° C. in the stress direction and the vertical direction, and calculate by the following formula. Was.

[0035]

## EQU4 ## Absolute value of dimensional change rate = │dimensional change / distance between chucks│ × 100

Example 1 PEN having an intrinsic viscosity of 0.62
The polymer was melted by an extruder, extruded from a die onto a rotating cooling drum maintained at 40 ° C., and the molten polymer was closely adhered to the rotating cooling drum by using an electrostatic adhesion method and rapidly cooled to obtain an unstretched film. Next, this unstretched film was stretched 3.7 times in the machine direction and then 3.8 times in the transverse direction, and heat-set at 240 ° C. to obtain a biaxially oriented PEN film having a thickness of 50 μm.

On one surface of the biaxially oriented PEN film, the following coating solution 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 to form a release layer. A release film having a thickness of 0.15 μm was prepared.
The coating liquid was obtained 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 curing the silicone resin with the curable silicone. A solution having a solid content ratio of 10% by weight with respect to silicone was added to form a solution having a total solid content of 2%, and a platinum catalyst was added to this solution to prepare a solution. Table 1 shows the characteristics of the release film.

Comparative Example 1 PET with an intrinsic viscosity of 0.62
The polymer was melted by an extruder, extruded from a die onto a rotating cooling drum maintained at 40 ° C., and the molten polymer was adhered to the rotating cooling drum using an electrostatic adhesion method to be quenched to obtain an unstretched film. Next, this unstretched film was stretched 3.6 times in the longitudinal direction and 3.9 times in the transverse direction, and was heat-set at 220 ° C. to obtain a biaxially oriented PET film having a thickness of 50 μm.

On one surface of the biaxially oriented PET film, the following coating solution was applied at a coating amount of 6 g / m ² (wet), and was heated and dried at a temperature of 140 ° C. for one minute to form a release layer. A release film having a thickness of 0.15 μm was prepared.
The coating liquid was 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 having a total solid content of 2%. % Solution and a platinum catalyst was added to this solution. Table 1 shows the characteristics of the release film.

[0040]

[Table 1]

As is clear from Table 1, the release films of the present invention shown in Examples have a small surface roughness and are excellent in heat deformation resistance.

[0042]

The release film of the present invention uses a PEN film having a small surface roughness as a base film, so that the solvent removal at the time of forming a resin sheet or the like by heating with a high temperature and a high load can be performed. No deformation is observed, and sheets with high surface accuracy can be manufactured.

Claims (3)

[Claims] 1. A base film having a surface roughness Ra of 10
A release film which is a biaxially oriented polyethylene-2,6-naphthalenedicarboxylate film having a diameter of less than 150 nm, wherein an absolute value of a dimensional change rate under a stress of 150 gf / mm ^{2 at} 120 ° C. is determined by a stress direction and a perpendicular direction thereof. A release film characterized by being 0.2% or less in both directions. 2. The base film having an average particle size of 0.01
0.005 to 20 μm of inorganic or organic fine particles.
The release film according to claim 1, which is a biaxially oriented polyethylene-2,6-naphthalenedicarboxylate film containing 2% by weight. 3. 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.