JP2000343663A - Release film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a release film extremely reduced in thermal deformation at the time of heat treatment and excellent in subsequent cutting or punching processability in molding various resin sheets, resin films or ceramic sheets. SOLUTION: A release film has a film consisting of polyethylene naphthalate as a substrate film and, in the substrate film, a refractive index (nz) in a thickness direction is 1.49-1.53, a surface orientation coefficient (NS) is 0.23-0.27 and the sum of tear propagation resistance in a film roll taking-up direction and the direction vertical thereto is 4 N/mm or less.

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. And a release film having excellent thermal stability, processability, and flatness 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. The resin sheet is formed by applying (casting) a resin solution made of, for example, vinyl chloride onto a carrier film, removing the solvent by heating, and peeling and separating the carrier film, and used for applications such as marking sheets. Is done. The resin film is produced, for example, by applying a coating solution in which a resin serving as an adhesive is dissolved in a solvent to the surface of the carrier film, and then heating to remove the solvent. The 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 the carrier film, removing the solvent by heating, and removing and removing the carrier film.

[0003] In recent years, such resin sheets, resin coatings, ceramic sheets, and the like have been molded and manufactured using a release film. In particular, applications requiring high performance such as electronic components (such as ceramic electronic components such as capacitors and substrates) and optical components, especially ceramic sheets and resin sheets, are required to have a uniform thickness and high surface properties than ever before. I have. Capacitors are becoming thinner in order to increase their capacitance, and are often stacked in multiple layers, and are becoming ultra-miniaturized in size in order to mount them on many small mobile products such as mobile phones. In. In addition, in the case of ceramic substrates, IC packages and circuit boards have become more complex, and, like multilayer capacitors, technologies for multifunctionality, higher performance, and furthermore, smaller size and lighter weight have been developed. In particular, when a circuit is multilayered, more accurate ceramic molding and positioning thereof are important because wiring is performed through through holes to connect circuits between layers. This also requires similar performance for a resin substrate.

[0004] Therefore, it is necessary that such a resin sheet, a ceramic sheet, and the like have a uniform thickness, a smoother surface, and a precisely processed molded body. In order to manufacture such a sheet, not only high-precision equipment for applying a coating solution such as a resin solution, an adhesive or a ceramic slurry is required, but also release as a carrier film for forming the sheet. Films are also required to have dimensional stability after heat treatment when they are applied, and excellent workability in punching and cutting into desired sizes.

As the base film for the release film, various films, for example, an olefin film such as OPP, a biaxially oriented polyethylene terephthalate (hereinafter sometimes abbreviated as PET) film and the like are used. After the release film is coated with a resin solution or a ceramic slurry, it is subjected to a heat treatment to remove the solvent. The heating temperature is close to or near the glass transition temperature (Tg) of the base film used for the release film. In many cases, thermal deformation such as dimensional change and wrinkles occurs in the release film, and there is a problem that the thickness unevenness and flatness of the formed resin sheets are deteriorated and the quality is deteriorated. 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. For this reason, a base film excellent in heat resistance at least is preferred.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art, and to minimize the thermal deformation during heat treatment in forming various resin sheets, resin coatings, ceramic sheets, and the like. An object of the present invention is to provide a release film excellent in processability such as subsequent cutting and punching.

[0007]

According to the present invention, an object of the present invention is a release film having a base film made of a film made of polyethylene naphthalate. Rate (nz) is 1.49
1.53 or less, the plane orientation coefficient (NS) is 0.23 or more and 0.27 or less, and the sum of the tear propagation resistance in the film roll winding direction and the vertical direction is 4 N / mm or less. This is achieved by a release film.

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,
Examples thereof include 2,7-naphthalenedicarboxylic acid and 1,5-naphthalenedicarboxylic acid. Of these, 2,6-naphthalenedicarboxylic acid is preferred. When the main acid component is not naphthalenedicarboxylic acid, it is not preferable because, for example, the film is formed into a film, and a rolled-up film remains and the flatness of the film is impaired.

Such a PEN polymer may be used, for example, aromatic dicarboxylic acids (terephthalic acid, isophthalic acid, diphenylethanedicarboxylic acid, diphenyldicarboxylic acid, diphenyletherdicarboxylic acid, diphenylsulfonedicarboxylic acid) as long as the thermal deformation resistance of the release film is not impaired. , 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.

The glycol components other than ethylene glycol constituting the PEN film include aliphatic glycols (for example, those having 3 to 10 carbon atoms such as trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, and decamethylene glycol).
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) And the like, but the proportion of these other glycol components is preferably 20 mol% or less based on all 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, the PEN polymer is obtained by blocking some or all of the terminal hydroxyl groups and / or carboxyl groups with a monofunctional compound such as benzoic acid or methoxypolyalkylene glycol. There may be.

The PEN film of 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 substrate film used in the present invention preferably has an intrinsic viscosity in an o-chlorophenol solution at 25 ° C. of from 0.40 to 0.90 dl / g, particularly from 0.50 to 0.90 dl / g. It is preferably in the range of 0.85 dl / g. When the intrinsic viscosity is in the above range, the extrudability and film-forming properties of the molten PEN polymer are improved, and a polyester film having excellent heat resistance is easily obtained, and the film is cut into a predetermined size and punched. Burrs and the like do not occur, and the moldability is improved. 0.4 intrinsic viscosity
If it is less than 0 dl / g, the film becomes too brittle, burrs are generated on the end face when the film is cut into a predetermined size, and sometimes a part of the burrs is cracked, and the product yield is deteriorated. Further, the intrinsic viscosity of the base film is 0.90 d.
If it exceeds 1 / g, the intrinsic viscosity of the PEN polymer itself must be considerably increased, and the polymerization method requires a long time for polymerization, resulting in poor productivity. In addition, a special polymerization method (such as solid-phase polymerization) requires dedicated equipment, which increases the production cost.

The PEN polymer in the present invention has a mean particle size of 0.01 in order to impart lubricity and improve the winding property of the film as long as the effect is not impaired.
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. Such fine particles have a center line average roughness (Ra) of 2 on the substrate film surface.
%, For example, 0.001 to 10
% By weight, preferably 0.01 to 3% by weight
It is particularly preferable to include them. 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),
Inorganic fine particles such as lithium benzoate, barium sulfate, double salts of these compounds (including hydrates), carbon black, glass powder, clay (including kaolin, benite, clay, etc.), crosslinked acrylic resin, crosslinked polystyrene Organic fine particles such as a resin, a melamine resin, a crosslinked silicone resin, and a polyamideimide resin can be preferably exemplified. Such fine particles are preferably inert particles in order to maintain the effects of the present invention and 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 base 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).

[0016] Such a PEN 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 manufactured by a conventionally known method such as a sequential biaxial stretching method and a simultaneous biaxial stretching method. For example, in the sequential biaxial stretching method, the PEN polymer is sufficiently dried before its Tm
An unstretched film is produced by a melt extrusion method at a temperature of (Tm + 70) ° C. (Tm; melting point of the PEN polymer), and then the unstretched film is (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.
The film is stretched 2 to 6 times in the vertical direction at a temperature of (Tg + 50) ° C., and further (Tg + 60) to (Tg + 140)
It can be manufactured by heat setting at a temperature of 5 ° 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. The stretching conditions in the winding direction and in the vertical direction are preferably selected so that the physical properties of the obtained biaxially oriented PEN film are substantially equal in the longitudinal direction and the width direction. If the temperature is lower than (Tg + 70) ° C. at the heat setting temperature, there is a concern that when the film is stored in a rolled state with a film, a curl may sometimes remain or delamination may occur inside the film. On the other hand, if the temperature is higher than (Tg + 140) ° C., 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 of the present invention has a refractive index in the thickness direction of 1.49 or more and 1.53 or less, preferably 1.495 or more and 1.520 or less. If the refractive index in the thickness direction is less than 1.49, delamination of the film occurs or the bending resistance is deteriorated, so that fluffing or the like occurs during processing such as cutting, punching, and punching. Prone to problems. Further, when the refractive index in the thickness direction exceeds 1.53, the thickness unevenness of the film increases,
Wrinkles easily occur on the film surface.

The plane orientation coefficient (NS) of the substrate film in the present invention is from 0.23 to 0.27. When the plane orientation coefficient is less than 0.23, unevenness in thickness of the film becomes worse, and there is a concern that unevenness in thickness occurs in a resin sheet or a ceramic sheet obtained after applying a resin solution or ceramic slurry. Further, when the plane orientation coefficient exceeds 0.27, delamination is apt to occur, and scratches generated by scratching on the surface and edges are liable to become scratches having jaggedness (unevenness), and the delamination portions and scratch marks become white and conspicuous. Become.

In the present invention, the sum of the tear propagation resistance in the film roll winding direction of the base film and the vertical direction thereof is 4 N / mm or less. If the sum of the tear propagation resistances exceeds 4 N / mm, the punching properties of the film are undesirably reduced. The sum of the tear propagation resistance is 4N
/ Mm or less, the production conditions of the film may be selected, in particular, the stretching ratio may be set high within the above-mentioned range.

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

The base film in the present invention preferably has a film density of 1.360 to 1.380 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, resulting in poor dimensional stability. Also, 1.380
If it exceeds g / cm ³ , the film becomes brittle due to crystallization and the impact resistance is poor.

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.

The release film of the present invention has a temperature of 120.degree.
It is preferable that the absolute value of the dimensional change rate under a thermal stress of 0 gf / mm ² is 0.3% or less in both the roll winding direction of the base film and the vertical direction thereof. When the absolute value of the dimensional change rate exceeds 0.3%, in the step of applying a ceramic slurry or a resin solution to the release film and removing the solvent by heating, the release film is deformed and the ceramic sheet or the flat surface is removed. A resin sheet cannot be obtained.

In the present invention, it is preferable to provide a release layer on at least one side of the base film. As a component forming the release layer, for example, a silicone resin, a fluororesin or an aliphatic wax can be exemplified. 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 object of the present invention is not hindered. 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. Heating condition is 8
0-160 ° C for 10-120 seconds, especially 120-150
C. for 20 to 60 seconds is preferred. 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 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.

[0026]

The present invention will be further described below with reference to examples. In addition, each characteristic value was measured by the following method. 1. Refractive index (nz) in the thickness direction and plane orientation coefficient (NS) Using an Abbe refractometer (manufactured by Atago Co., Ltd.), using a Na-D line at 25 ° C., the film winding direction, its vertical direction, and the thickness direction. Was determined. The plane orientation coefficient is represented by the following equation. Plane orientation coefficient (NS) = (nMD + nTD) / 2-nz In the above formula, nMD is the refractive index of the base film in the film winding direction, nTD is the refractive index of the base film in the vertical direction, and nz is the refractive index in the thickness direction of the film. Represents

2. Elmendorf tear tester (manufactured by Toyo Seiki Seisaku-sho, Ltd.) was used as a tear propagation resistance tester. 52mm width (X) x 65
A rectangular film sample having a width of (mm) (mm) was taken, and a crack having a length of 13 mm was formed in the center of the X side in the Y direction.
The tearing force for 2 mm was determined. This force was divided by the thickness of the film to give a tear propagation resistance. This measurement was performed in the film winding direction and the direction perpendicular thereto.

3. Heat-Resistant Deformation A strip-shaped release film cut out at least 30 mm in width and 4 mm in width in the measurement direction is placed on a jig of TMA (thermal stress strain measuring device, TMA / SS120C manufactured by Seiko Denshi Kogyo Co., Ltd.) so that the distance between chucks is 10 mm. Attached, 150gf / m
After applying a stress of m ² and heating from room temperature at a heating rate of 5 ° C./min, the dimensional change when the temperature reached 120 ° C. was measured separately in the stress direction and the vertical direction, and calculated by the following formula. Absolute value of dimensional change rate = | Dimension change / Distance between chucks | ×
100

4. 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 15 cm square metal mold, after punching, the occurrence of burrs, corner bending, and cracks at the edges was observed and evaluated according to the following criteria. ：: No burr or bending occurs. Δ: Fine burrs or film bending occur, and the resin film slightly extends. 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.

Examples 1-2 and Comparative Examples 1-2 PEN polymers having an intrinsic viscosity shown in Table 1 containing 0.15% by weight of spherical silica particles having an average particle diameter of 0.3 μm were melted by an extruder. Then, the mixture was extruded from a die onto a rotating cooling drum maintained at 40 ° C., and the molten polymer was brought into close contact with the rotating cooling drum using an electrostatic adhesion method to be rapidly cooled to obtain an unstretched film.
Next, the unstretched film was biaxially stretched sequentially in the longitudinal (machine axis) direction and then in the transverse (width) direction in the order shown in Table 1, and then heat-fixed under the temperature conditions in Table 1 to obtain A biaxially oriented PEN film having a thickness of 50 μm was obtained.

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 adding 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.

[0033]

[Table 1]

As is clear from Table 1, the release films of the present invention shown in Examples have excellent heat stability as a base film and 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 have poor thermal stability after film formation, and thus have poor flatness, and further have poor flatness when formed into release films.
The thickness of the applied resin solution was poor, and delamination occurred during cutting, which was insufficient.

[0035]

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.

Claims (5)

[Claims] 1. A release film using a film made of polyethylene naphthalate as a base film, wherein (1) a refractive index (nz) in a thickness direction of the base film.
Is 1.49 or more and 1.53 or less, and the (2) plane orientation coefficient (N
S): 0.23 or more and 0.27 or less, and (3) a release film, wherein the sum of the tear propagation resistance in the film roll winding direction and the vertical direction is 4 N / mm or less. 2. The release film at 150 ° C. at 120 ° C.
releasing film of claim 1, wherein gf / mm the absolute value of the dimensional change rate under ² stress is 0.3% or less with the film roll winding direction and a vertical direction. 3. The base film has an intrinsic viscosity of 0.40 dl.
The release film according to claim 1, which is not less than / g and not more than 0.90 dl / g. 4. The base film having a thickness of 5 μm or more and 500 or more.
The release film according to any one of claims 1 to 3, which has a thickness of not more than μm. 5. 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.