JP2004188814A - Release film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a release film which shows successful coating film adhesive properties to a base material and a flat mold release surface and can, for example, endure its repeated use for molding a green sheet. <P>SOLUTION: This release film has a release layer formed on at least one side of a polyester film and the surface of the release layer satisfies formulae (1): F(CDL)≥40 and (2): P-V≤800 simultaneously, provided that F(CDL) is a critical breaking load (mN) and P-V is a maximum roughness (nm). <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００５８】
【表２】

【００５９】
【発明の効果】
本発明の離型フィルムは、離型層の塗膜密着性が良好でかつ離型面が平坦であり、特にセラミック基板、セラミック積層コンデンサー製造時に使用するグリーンシート成形用として、繰り返し（２回以上）使用に好適な離型フィルムを提供することができ、その工業的価値は極めて高い。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a release film, and more particularly to a release film suitable for repeated use, for example, for forming a green sheet used in manufacturing a ceramic substrate and a ceramic multilayer capacitor.
[0002]
[Prior art]
Conventionally, a release film based on a polyester film has been used for various types of release such as green sheet molding, protection of an adhesive layer, and the like. In the case where the release roll of the release film comes into contact with the transport roll, the smaller the embedment angle of the release film via the transport roll, the smaller the release film is in contact with the transport roll surface. Since the contact pressure on the release surface tends to increase, problems such as scraping of the release layer may occur with the continuous processing.
[0003]
In recent years, in consideration of environmental issues such as cost reduction or acquisition of the ISO 14000 series, there has been a tendency to reduce the amount of release films that ultimately become industrial waste. In some cases, the mold film is used repeatedly (two or more times), and the above-described problems are more likely to occur.
On the other hand, in the case of ceramic release, it has become necessary for the release surface to be flatter in order to obtain a more accurate green sheet.
[0004]
[Patent Document 1] Japanese Patent Application Laid-Open No. 2000-74819
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and a problem to be solved is to provide a release film which has good coating adhesion to a substrate, has a flat release surface, and can withstand repeated use. It is in.
[0006]
[Means for Solving the Invention]
The present inventors have conducted intensive studies in view of the above-mentioned circumstances, and as a result, have found that the use of a release film having a specific configuration can easily solve the above-described problems, and have completed the present invention.
[0007]
That is, the gist of the present invention is a film having a release layer on at least one side of a polyester film, wherein the release layer surface satisfies the following formulas (1) and (2) simultaneously. Exists.
(In the above formula, F (CDL) represents critical breaking load (mN), and PV represents maximum roughness (nm).)
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in more detail.
In the present invention, the polyester used for the polyester film may be a homopolyester or a copolyester.
In the case of a homopolyester, those obtained by polycondensing an aromatic dicarboxylic acid and an aliphatic glycol are preferred. Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid, and examples of the aliphatic glycol include ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol. Representative polyesters include polyethylene terephthalate (PET), polyethylene-2,6-naphthalenedicarboxylate (PEN), and the like.
[0009]
On the other hand, in the case of a copolyester, it is preferably a copolymer containing 30 mol% or less of the third component. As the dicarboxylic acid component of the copolymerized polyester, one or two kinds of isophthalic acid, terephthalic acid phthalate, 2,6-naphthalenedicarboxylic acid, sebacic acid adipic acid, oxycarboxylic acid (for example, P-oxybenzoic acid) and the like are used. The above is mentioned, and as the glycol component, one or more kinds of ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol and the like are mentioned.
[0010]
In any case, the polyester in the present invention means polyethylene terephthalate whose ethylene terephthalate unit is usually 80 mol% or more, preferably 90 mol% or more, and polyethylene-2,6-naphthalate which is an ethylene-2,6-naphthalate unit. And the like.
In the polyester layer of the present invention, particles are preferably blended for the purpose of mainly providing lubricity. The type of particles to be compounded is not particularly limited as long as the particles can impart lubricity, and specific examples include, for example, silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, and magnesium phosphate. , Kaolin, aluminum oxide, titanium oxide and the like. Further, heat-resistant organic particles described in JP-B-59-5216 and JP-A-59-217755 may be used. Examples of other heat-resistant organic particles include a thermosetting urea resin, a thermosetting phenol resin, a thermosetting epoxy resin, a benzoguanamine resin, and the like. Further, during the polyester production process, precipitated particles in which a part of a metal compound such as a catalyst is precipitated and finely dispersed can be used.
[0011]
On the other hand, the shape of the particles to be used is not particularly limited, and any of spherical, massive, rod-like, flat, and the like may be used. There is no particular limitation on the hardness, specific gravity, color and the like. These series of particles may be used in combination of two or more as necessary.
The average particle size of the particles used preferably satisfies 0.1 to 5 μm, more preferably 0.5 to 3 μm. When the average particle size is less than 0.1 μm, the particles tend to aggregate and dispersibility tends to be insufficient, while when it exceeds 5 μm, the surface roughness of the film becomes too coarse, Problems may occur when a release layer is provided in a later step.
[0012]
Further, the content of particles in the polyester preferably satisfies 0.01 to 5% by weight, more preferably 0.01 to 3% by weight. If the particle content is less than 0.01% by weight, the lubricity of the film may be insufficient, while if it exceeds 5% by weight, the smoothness of the film surface may be insufficient. In some cases.
The method for adding particles to the polyester is not particularly limited, and a conventionally known method can be employed. For example, it can be added at any stage of producing the polyester, but preferably the polycondensation reaction may be advanced after the esterification stage or after the transesterification reaction is completed. Also, a method of blending a slurry of particles dispersed in ethylene glycol or water with a polyester raw material using a kneading extruder with a vent, or a method of blending dried particles and a polyester raw material with a kneading extruder And so on.
[0013]
The thickness of the polyester film constituting the release film of the present invention is not particularly limited, but is usually in the range of 12 to 350 µm, preferably 12 to 250 µm.
Next, production examples of the film of the present invention will be specifically described, but the invention is not limited to the following production examples.
[0014]
First, it is preferable to use the above-mentioned polyester raw material and cool and solidify a molten sheet extruded from a die with a cooling roll to obtain an unstretched sheet. In this case, it is necessary to increase the adhesion between the sheet and the rotary cooling drum in order to improve the flatness of the sheet, and the electrostatic application adhesion method and / or the liquid application adhesion method are preferably employed. Next, the obtained unstretched sheet is stretched biaxially. In that case, first, the unstretched sheet is stretched in one direction by a roll or tenter type stretching machine. The stretching temperature is usually 70 to 120 ° C, preferably 80 to 110 ° C, and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Next, the stretching temperature orthogonal to the stretching direction of the first step is usually 130 to 170 ° C., and the stretching ratio is usually 3.0 to 7 times, preferably 3.5 to 6 times. Then, a heat treatment is successively performed at a temperature of 180 to 270 ° C. under tension or relaxation within 30% to obtain a biaxially oriented film. In the above-mentioned stretching, a method of performing unidirectional stretching in two or more steps may be employed. In that case, it is preferable that the stretching is performed in such a manner that the stretching ratio in the two directions finally falls within the above range. It is also possible to simultaneously biaxially stretch the unstretched sheet so that the area magnification becomes 10 to 40 times. If necessary, the film may be stretched in the longitudinal and / or transverse directions again before or after the heat treatment.
[0015]
A so-called coating / stretching method (in-line coating) for treating the film surface during the above-mentioned stretching step of the polyester film can be performed. Although it is not particularly limited, for example, in the sequential biaxial stretching, the coating process can be performed before the second stage stretching, particularly after the first stage stretching is completed. When a coating layer is provided on a polyester film by the coating and stretching method described above, coating can be performed simultaneously with stretching, and the thickness of the coating layer can be reduced according to the stretching ratio, which is suitable as a polyester film. Film can be manufactured.
[0016]
The release layer constituting the release film of the present invention is not particularly limited as long as it contains a material having a release property. Among such materials, the use of a curable silicone resin is preferable because the releasability is particularly improved.
The resin to be used may be a type containing a curable silicone resin as a main component, or a modified silicone type obtained by graft polymerization with an organic resin such as a urethane resin, an epoxy resin, or an alkyd resin. As the type of the curable silicone resin, any of a curing reaction type such as an addition type, a condensation type, an ultraviolet curable type, an electron beam curable type, and a solventless type can be used. Further, a modified silicone type by graft polymerization with an organic resin such as an acrylic resin, a urethane resin, an epoxy resin, or an alkyd resin, or the like may be used as needed within a range not to impair the gist of the present invention.
[0017]
As specific examples, KS-774, KS-775, KS-778, KS-779H, KS-847H, KS-5508, KS-856, X-62-2422, X-62-, manufactured by Shin-Etsu Chemical Co., Ltd. 2461, DKQ3-202, DKQ3-203, DKQ3-204, DKQ3-205, DKQ3-210, Dow Corning Asia Ltd., YSR-3022, TPR-6700, TPR-6720, TPR, manufactured by Toshiba Silicone Co., Ltd. -6721, Dow Corning Toray Silicone Co., Ltd. SD7220, SD7226, SD7229, LTC750A and the like.
[0018]
In addition, a release control agent may be used in combination to adjust the release property of the release layer.
In the present invention, the coating amount of the release layer (after drying) is generally 0.01-5 g / ^{m 2,} preferably from 0.01 to 2 g / ^{m 2,} more preferably in the range of 0.01 to 1 g / ^{m 2} It is. When the coating amount of the release layer is less than 0.01 g / m ² , stability may be lacked from the viewpoint of coatability, and it may be difficult to obtain a uniform coating film. On the other hand, when the coating amount exceeds 5 g / m ² , the adhesion of the coating film, the curability, and the like of the release layer itself may be reduced.
[0019]
In the present invention, as a method of providing a release layer on the polyester film, a conventionally known coating method such as reverse gravure coating, bar coating, and die coating can be used.
The polyester film constituting the release film in the present invention may be subjected to a surface treatment such as a corona treatment or a plasma treatment in advance. Further, the polyester film constituting the release film in the present invention may be provided in advance with a coating layer such as an adhesive layer and an antistatic layer.
[0020]
The release film of the present invention needs to have a critical breaking load (F (CDL)) of at least 40 mN on the surface of the release layer, and preferably at least 45 mN, in order to improve the coating adhesion of the release layer. , More preferably 50 mN or more. When F (CDL) is less than 40 mN, the adhesion of the release layer to the polyester film is poor. For example, in the case of green sheet molding, when the release film is used repeatedly (two or more times) during the processing step. Becomes inappropriate.
The maximum roughness (PV) of the release layer surface of the release film of the present invention must be 800 nm or less, preferably 600 nm or less, more preferably 400 nm or less. When PV exceeds 800 nm, the flatness of the release surface becomes insufficient, and for example, it becomes difficult to obtain a green sheet having a flat surface. On the other hand, the lower limit of PV is preferably set to 100 nm in consideration of the winding property or transportability of the release film.
[0021]
The heat shrinkage in the longitudinal direction (MD direction) of the release film of the present invention (after heat treatment at 100 ° C. for 30 minutes) is 0.10% or less, and more preferably 0% or less, in order to improve the flatness of the release film. 0.08% or less is preferable. When the heat shrinkage ratio exceeds 0.10%, when the drying temperature condition during green sheet molding is set higher and used repeatedly, the dimensional change becomes large, which may cause problems such as film thickening or meandering.
As a specific method for satisfying the above-mentioned heat shrinkage, a method of providing a release layer on a polyester film and then performing an annealing treatment is exemplified.
[0022]
In the release film of the present invention, the peeling force (F) between the release surface and the acrylic pressure-sensitive adhesive tape is preferably in the range of 10 to 300 mN / cm, more preferably in the range of 10 to 200 (mN / cm). . When F is less than 10 mN / cm, the green sheet may be easily peeled off in a scene where it is not necessary to peel off the green sheet. On the other hand, when F exceeds 300 mN / cm, for example, in the case of green sheet molding, it may be difficult to peel off the green sheet.
[0023]
Regarding the release film in the present invention, the residual adhesion rate of the release layer is 90% or more in order to suppress the transfer or transfer of silicone to the surface of the mating base material (eg, green sheet, adhesive layer, etc.) to be bonded. Preferably, it is more preferably 95% or more. When the residual adhesive ratio is less than 90%, the transfer of silicone to the mating substrate surface in contact with the release surface of the release film increases, and, for example, in green sheet molding, the inter-sheet adhesiveness decreases during green sheet lamination. Etc. may occur.
[0024]
【Example】
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. The measuring method used in the present invention is as follows.
[0025]
(1) Measurement of Intrinsic Viscosity of Polyester 1 g of polyester from which other polymer components and pigments incompatible with polyester were removed was precisely weighed, and 100 ml of a mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio) was added. Dissolved and measured at 30 ° C.
[0026]
(2) Measurement of average particle diameter (d ₅₀ : μm) Integration (weight basis) in equivalent spherical distribution measured using a centrifugal sedimentation type particle size distribution analyzer (SA-CP3, manufactured by Shimadzu Corporation) The value of 50% was defined as the average particle size.
[0027]
(3) Evaluation of Release Force (F) of Release Film After one side of a double-sided adhesive tape (“No. 502” manufactured by Nitto Denko) was attached to the release layer of the measurement sample, it was cut into a size of 50 mm × 300 mm. The peeling force after leaving at room temperature for 1 hour was measured. The peeling force was measured by using a tensile tester ("Intesco Model 2001" manufactured by Intesco Corporation), and 180 ° peeling was performed under the condition of a tensile speed of 300 mm / min.
[0028]
(4) Measurement of coating amount of release layer Using an X-ray fluorescence spectrometer (model “XRF-1500”, manufactured by Shimadzu Corporation), by the FP (Fundamental Parameter Method) method under the following measurement conditions, The amounts of silicon elements on the surface of the mold film on which the release layer was provided and on the surface without the release layer were measured, and the difference was used as the silicon element amount in the release layer.
Next, using the obtained silicon element amount, the coating amount (Si) (g / m ² ) as a unit of —SiO (CH ₃ ) ₂ was calculated.
"Measurement condition"
Spectral crystal: PET (pentaerythritol)
2θ: 108.88 °
Tube current: 95mA
Tube voltage: 40kv
In the case of a release layer containing no silicon, the thickness was separately measured by an optical method.
[0029]
(5) Measurement of Critical Breaking Load (F (CDL)) of Release Surface of Release Film The release surface of the sample film was measured using an ultra-thin scratch tester (CSR-02 type) manufactured by Resca Co., Ltd. After repeated measurements, the critical breaking load (F (CDL)) was defined as the measured average value of the remaining 10 points excluding the maximum value and the minimum value.
"Measurement condition"
Sensor: No. 1
Load (g / mm): 238.75
Stylus diameter (μm): 15
Excitation level (μm): 80
Load Rate (mN / mm): Automatic calculation Gain: 1000
Stage Angle (deg): 2.00
Stage Speed (μm / s): 10.0
[0030]
(6) Evaluation of Maximum Roughness (PV) of Release Surface of Release Film Non-contact surface measurement system "Micromap" using direct beam detection interferometry, so-called two-beam interferometry utilizing Michelson interference Micromap 512) ", the maximum roughness (PV) of the release surface of the sample film was measured. The measurement wavelength was 554 nm, the objective lens was used at a magnification of 20 times, 20 fields of view were measured, and the average value was adopted.
[0031]
(7) Evaluation of Residual Adhesion Rate of Release Film (1) Residual Adhesive Strength Nitto Denko No. The 31B pressure-sensitive adhesive tape was pressed back and forth with a 2 kg rubber roller once and heated at 100 ° C. for 1 hour. Next, No. 1 was obtained from the crimped sample. The 31B adhesive tape is peeled off, and the adhesive strength is measured according to the method of JIS-C-2107 (adhesive strength to stainless steel plate, 180 ° peeling method). This was defined as the residual adhesive force.
[0032]
{Circle around (2)} Basic adhesive strength An adhesive tape was pressed against a stainless steel plate using the same tape (No. 31B) as in the case of the residual adhesive strength according to JIS-C-2107, and the measurement was performed in the same manner. The value at this time was defined as the basic adhesive strength. Using these measured values, the residual adhesion rate was determined based on the following equation.
Residual adhesion rate (%) = (Residual adhesive strength / Basic adhesive strength) × 100
The measurement was performed at 20 ± 2 ° C. and 65 ± 5% RH.
[0033]
(8) Evaluation of Heat Shrinkage Ratio in Release Film Longitudinal (MD) Direction After cutting a sample film into a 15 cm wide strip of 15 cm length in the film longitudinal (MD) direction, under a 23 ± 2 ° C., 50 ± 5% RH atmosphere. After humidity control for 24 hours, the length in the film longitudinal (MD) direction was measured with a micrometer (Nikon factory microscope). Next, the sample film was heat-treated in a hot-air oven at 100 ° C. for 30 minutes under no tension, taken out of the oven, and allowed to stand at 23 ± 2 ° C. and 50 ± 5% RH for 1 hour. Thereafter, the length of the heat-treated sample film in the MD (longitudinal) direction was measured by a micrometer, and the heat shrinkage was determined by the following equation.
Heat shrinkage (%) = [(ab) / a] × 100
(In the above formula, a represents the length in the sample film MD (longitudinal) direction before the heat treatment, and b represents the length in the sample film MD (longitudinal) direction after the heat treatment.)
[0034]
(9) Evaluation of promotion of coating film adhesion of release film (substitution evaluation of practical characteristics)
The sample film was left in a thermo-hygrostat at 60 ° C. and 70% RH for 48 hours (2 days), and then the sample film was taken out. Thereafter, the release surface of the sample film was rubbed five times with a tentacle, and the degree of detachment of the release layer was determined according to the following criteria.
《Criteria》
…: No peeling of the coating film is observed (a level that does not cause a problem in practical use)
△: The coating film turns white but does not fall off (a level that does not cause any problem in practical use)
×: Dropping of the coating film was confirmed (a level with practical problems)
[0035]
(10) Evaluation of flatness of green sheet (substitution evaluation of practical characteristics)
Using a sample film, a ceramic slurry having the following composition was applied so that the applied amount (after drying) was 7 (g / m ² ), dried at 120 ° C. for 1 minute in a hot-air oven, and then released from the release surface. The green sheet was peeled off, and the maximum roughness (PV) of the surface of the green sheet on the side in contact with the release surface was measured according to the measurement procedure described in (6).
[0036]
《Ceramic slurry composition》
20 parts of barium titanate (Fuji Titanium (manufactured by) HPBT-1 average particle diameter: 0.63 μm), 20 parts of polyvinyl butyral resin (Sekisui Chemical (manufactured by) SREC series: “BM-S” type) 20 parts, dioctyl phthalate 5 Parts, toluene / ethanol mixed solvent (mixing ratio is 6: 4) 50 parts
《Criteria》
…: The PV value of the green sheet surface is 400 nm or less △: the PV value of the green sheet surface exceeds 400 nm and 700 nm or less ×: the PV value of the green sheet surface exceeds 700 nm
(11) Heat shrinkage measurement in MD direction after heat treatment of release film (Film flatness substitution evaluation)
Using a 1000 mm wide roll-shaped sample film, under a tension of 2 MPa,
Heat treatment was performed at 100 ° C. for 1 minute. Thereafter, the heat shrinkage in the sample film MD (longitudinal) direction was measured at two locations at both ends using a micrometer (Nikon factory microscope) in accordance with the measurement procedure described in (8), and the heat shrinkage was calculated by the following equation. The flatness of the film was determined based on the rate difference.
《Criteria》
…: The difference in thermal shrinkage at both ends of the sample film is less than 0.02%: good flatness (level that is not problematic in practical use)
C: Difference in heat shrinkage at both ends of sample film is 0.02% or more: poor flatness (a level that is problematic in practical use)
| Heat shrinkage difference (%) | = [(a1−b1) / a1] × 100
(In the above formula, a1 is the heat shrinkage at the end of the sample film (left), b1 is the heat shrinkage at the end of the sample film (right), | heat shrinkage difference (%) | is the absolute value of the heat shrinkage difference Represents)
The larger the absolute value of the difference in the heat shrinkage ratio, the lower the film flatness, the more likely it is that a problem such as bulging or meandering occurs during processing, and it becomes difficult to cope with repeated (two or more) uses.
[0039]
<Manufacture of polyester>
Production Example 1 (Polyethylene terephthalate A1)
86 parts of terephthalic acid and 70 parts of ethylene glycol were placed in a reactor and transesterification was performed at about 250 ° C. for 4 hours. 0.03 part of antimony trioxide, 0.01 part of phosphoric acid, and 0.1 part of silicon dioxide particles having an average particle size of 1.5 μm are added, and the temperature is gradually raised from 250 ° C. to 285 ° C. and the pressure is gradually reduced. 0.5 mmHg. After 4 hours, the polymerization reaction was stopped to obtain polyethylene terephthalate A1 having an intrinsic viscosity of 0.65.
[0040]
Production Example 2 (Polyethylene terephthalate A2)
Produced in the same manner as in Production Example 2 except that 0.1 parts of silicon dioxide particles having an average particle size of 0.1 μm were used instead of 0.1 parts of silicon dioxide particles having an average particle size of 1.5 μm. Thus, polyethylene terephthalate A2 was obtained.
[0041]
Production Example 3 (Polyethylene terephthalate A3)
Produced in the same manner as in Production Example 2, except that 6 parts of silicon dioxide particles having an average particle size of 1.5 μm were used instead of 0.1 parts of silicon dioxide particles having an average particle size of 1.5 μm, Terephthalate A3 was obtained.
[0042]
<Manufacture of polyester film>
Production Example 4 (PET film F1)
The polyethylene terephthalate A1 produced in Production Example 1 was dried at 180 ° C. in an inert gas atmosphere for 4 hours, melted at 290 ° C. by a melt extruder, extruded from a die, and brought to a surface temperature of 40 using an electrostatic application adhesion method. The mixture was cooled and solidified on a cooling roll set at a temperature of ° C to obtain an undrawn sheet. The obtained sheet was stretched 3.5 times in the longitudinal direction at 85 ° C.
Next, after applying a coating layer having the following coating composition so that the coating amount (after drying) is 0.05 (g / m ² ), the film is guided to a tenter and 3.5 times at 100 ° C. in the horizontal direction. After that, the film was heat-set at 230 ° C. to obtain a PET film F1 having a thickness of 38 μm.
[0043]
《Coating composition》
(1) 90% by weight of γ-glycidoxypropyltrimethoxysilane, (2) 10% by weight of polyvinyl alcohol resin (degree of saponification = 88 mol%, degree of polymerization = 500)
A 2% by weight aqueous acetic acid solution was prepared from the above-mentioned coating composition.
[0044]
Production Example 5 (PET film F2)
In Production Example 4, a PET film F2 having a thickness of 38 μm was obtained in the same manner as in Production Example 4, except that the polyethylene terephthalate A2 produced in Production Example 2 was used instead of the polyethylene terephthalate A1.
[0045]
Production Example 6 (PET film F3)
In Production Example 4, a PET film F3 having a thickness of 38 μm was obtained in the same manner as in Production Example 4, except that the polyethylene terephthalate A3 produced in Production Example 3 was used instead of the polyethylene terephthalate A1.
Production Example 7 (PET film F4)
In Production Example 4, a PET film F4 having a thickness of 38 μm was obtained in the same manner as in Production Example 4, except that no coating layer was provided.
[0046]
Example 1
A release agent having the following release agent composition was applied onto the coating layer of the PET film F2 obtained in Production Example 4 such that the application amount (after drying) was 0.1 (g / m ² ), and 120 ° C. After heat treatment for 30 seconds, a release film was obtained. Further, the obtained release film was annealed at 200 ° C. for 10 seconds under no tension.
<< Release agent composition >>
20 parts of curable silicone resin (KS-847H: manufactured by Shin-Etsu Chemical), 1 part of curing agent (PL-50T: manufactured by Shin-Etsu Chemical), 400 parts of toluene / MEK mixed solvent (mixing ratio is 1: 1) 400 parts
Example 2
In Example 1, a release film was obtained in the same manner as in Example 1 except that the PET film F1 was used instead of the PET film F2.
[0048]
Example 3
In Example 1, a release film was obtained in the same manner as in Example 1, except that the composition of the release agent was changed to the following composition of the release agent.
<< Release agent composition >>
20 parts of curable silicone resin (KS-774: manufactured by Shin-Etsu Chemical), 1 part of curing agent (PL-3: manufactured by Shin-Etsu Chemical), 400 parts of toluene / MEK mixed solvent (mixing ratio is 1: 1) 400 parts
Example 4
In Example 1, a release film was obtained in the same manner as in Example 1, except that the annealing conditions were different at 160 ° C. for 10 seconds.
Example 5
In Example 1, a release film was obtained in the same manner as in Example 1 except that the annealing treatment was not performed.
[0050]
Example 6
In Example 5, the composition of the release agent was changed to the following composition of the release agent, and “Diafoil (registered trademark): T300 type-38 μm” manufactured by Mitsubishi Chemical Polyester Film Co., Ltd. was used instead of the PET film F2. Except for the above, it was manufactured in the same manner as in Example 6 to obtain a release film.
<< Release agent composition >>
20 parts of curable silicone resin (X-62-5508: manufactured by Shin-Etsu Chemical), 1 part of curing agent (PL-5000: manufactured by Shin-Etsu Chemical), 0.5 part of adhesion improver (X-92-185: manufactured by Shin-Etsu Chemical) 400 parts of toluene / MEK mixed solvent (mixing ratio is 1: 1)
Example 7
In Example 6, except that “Diafoil (registered trademark): T100 type -38 μm” manufactured by Mitsubishi Chemical Polyester Film Co., Ltd. was used instead of “Diafoil (registered trademark): T100 type -38 μm” manufactured by Mitsubishi Chemical Polyester Film Co., Ltd. It was manufactured in the same manner as in Example 6 to obtain a release film.
[0052]
Example 8
In Example 6, except that “Diafoil (registered trademark): T300 type-38 μm” manufactured by Mitsubishi Chemical Polyester Film Co., Ltd. was used instead of “Diafoil (registered trademark): T100 type—50 μm” manufactured by Mitsubishi Chemical Polyester Film Co., Ltd. It was manufactured in the same manner as in Example 6 to obtain a release film.
[0053]
Example 9
In Example 6, except that “Diafoil (registered trademark): T100 type -38 μm” manufactured by Mitsubishi Chemical Polyester Film Co., Ltd. was used instead of “Diafoil (registered trademark): T100 type -75 μm” manufactured by Mitsubishi Chemical Polyester Film Co., Ltd. It was manufactured in the same manner as in Example 6 to obtain a release film.
[0054]
Example 10
In Example 6, except that "Diafoil (registered trademark): T300 type-38 m" manufactured by Mitsubishi Chemical Polyester Film Co., Ltd. was used instead of "Diafoil (registered trademark): T100 type-100 m" manufactured by Mitsubishi Chemical Polyester Film Co., Ltd. It was manufactured in the same manner as in Example 6 to obtain a release film.
[0055]
Comparative Example 1
In Example 1, a release film was obtained in the same manner as in Example 1 except that the PET film F4 was used instead of the PET film F1.
[0056]
Comparative Example 2
In Example 1, a release film was obtained in the same manner as in Example 1 except that the PET film F3 was used instead of the PET film F1.
The characteristics of each film obtained in the above Examples and Comparative Examples are summarized in Tables 1 and 2 below.
[0057]
[Table 1]

[0058]
[Table 2]

[0059]
【The invention's effect】
The release film of the present invention has good coating adhesion of the release layer and a flat release surface. In particular, the release film is used repeatedly (two or more times) for forming a green sheet used in the production of ceramic substrates and ceramic multilayer capacitors. ) A release film suitable for use can be provided, and its industrial value is extremely high.

Claims (4)

A release film having a release layer on at least one side of a polyester film, wherein the release layer surface satisfies the following formulas (1) and (2) simultaneously.
F (CDL) ≧ 40… ▲ 1 ▼
PV ≦ 800… ▲ 2 ▼
(In the above formula, F (CDL) represents critical breaking load (mN), and PV represents maximum roughness (nm).) The release film according to claim 1, wherein the release layer contains a curable silicone resin. The release film according to claim 1, wherein a heat shrinkage in a longitudinal direction (100 ° C., 30 minutes) is 0.10% or less. The release film according to any one of claims 1 to 3, which is used for green sheet molding.