JP4391858B2 - Release film for green sheet molding - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a release film, and in particular, for green sheet forming used in the production of ceramic electronic components such as ceramic multilayer capacitors and ceramic substrates, the green sheet is peeled vertically from the release surface of the release film by vacuum suction or the like. It is related with the release film which can respond to the peeling process which employs what is called a surface peeling system.

  Conventionally, a release film based on a polyester film has been used for forming a green sheet used in manufacturing various ceramic electronic components such as a ceramic multilayer capacitor and a ceramic substrate. In recent years, as the ceramic multilayer capacitor has been reduced in size and capacity, the thickness of the green sheet tends to become thinner. With the further thinning of the green sheet, especially when trying to form a thin green sheet with a thickness of 2 μm or less, when the surface roughness of the release layer surface of the release film is high, the slurry is applied during ceramic slurry coating. There may be problems such as repellency or pinholes, and green sheet breakage when the green sheet is peeled off.

  In order to solve the above problems, if a release film based on a polyester film having a low surface roughness is used, blocking or wrinkles may occur when the release film is wound into a roll. May occur.

  On the other hand, in the green sheet peeling process, a so-called surface peeling method in which the green sheet is peeled in the vertical direction from the release surface by vacuum suction or the like may be employed (examples described in Patent Documents 1 and 2). ). In the peeling process that employs the surface peeling method, it is sometimes difficult to cope with a release film that is conventionally used for ceramic release. Therefore, there is a need for a release film that has a flat release surface and can handle a peeling process for peeling the green sheet.

Japanese Patent Laid-Open No. 2000-49060 JP 2002-254421 A JP 2002-67018 A

  The present invention has been made in view of the above circumstances, and its solution is to form a green sheet in a direction perpendicular to the mold release surface for forming a green sheet used when manufacturing various electronic components such as ceramic multilayer capacitors and ceramic substrates. It is intended to provide a release film that can be applied to a peeling process employing a so-called surface peeling method.

  As a result of intensive studies in view of the above circumstances, the present inventors have found that the above-mentioned problems can be easily solved by using a release film having a specific configuration, and have completed the present invention.

That is, the gist of the present invention is a film having a release layer containing a silicone compound having a T unit (SiO _3/2 ) structure on one surface of a polyester film, and the following formulas (1) and (2 ) At the same time, a release film for forming a green sheet.
F (300 m / min) / F (30 m / min) ≦ 2.0 (1)
0.01 ≦ Si ≦ 0.10 (2)
(In the above formula, F (300 m / min) and F (30 m / min) are release films, and the release force between the release layer surface and the acrylic pressure-sensitive adhesive tape at release rates of 300 m / min and 30 m / min, respectively ( mN / cm), Si represents the thickness (g / m ² ) of the release layer.

Hereinafter, the present invention will be described in more detail.
The polyester film constituting the release film of the present invention may have a single layer structure or a laminated structure. For example, A / B, A / B / A, A / B / C, A / B / In addition to the two-layer and three-layer structure such as A ′, four or more layers may be used as long as the gist of the present invention is not exceeded, and there is no particular limitation.

  Furthermore, the polyester used for the polyester film may be a homopolyester or a copolyester. In the case of a homopolyester, those obtained by polycondensation of 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.

  On the other hand, in the case of a copolymerized polyester, a copolymer containing 30 mol% or less of the third component is preferable. Examples of the dicarboxylic acid component of the copolyester include one or two of isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid sebacic acid, oxycarboxylic acid (for example, P-oxybenzoic acid), and the like. The glycol component includes one or more of ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, and the like.

  In any case, the polyester referred to in the present invention is usually 80 mol% or more, preferably 90 mol% or more of polyethylene terephthalate having ethylene terephthalate units and polyethylene-2,6-naphthalate having ethylene-2,6-naphthalate units. Refers to a polyester that is the like.

  In the polyester layer in the present invention, it is preferable to blend particles for the main purpose of imparting slipperiness. The kind of the particle to be blended is not particularly limited as long as it is a particle capable of imparting slipperiness. Specific examples thereof include silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, and phosphoric acid. Examples of the particles include magnesium, kaolin, aluminum oxide, and titanium oxide. Further, heat-resistant organic particles as described in JP-B-59-5216, JP-A-59-217755 and the like may be used. Examples of other heat-resistant organic particles include thermosetting urea resins, thermosetting phenol resins, thermosetting epoxy resins, benzoguanamine resins, and the like. Furthermore, precipitated particles obtained by precipitating and finely dispersing a part of a metal compound such as a catalyst during the polyester production process can also be used.

  On the other hand, the shape of the particles to be used is not particularly limited, and any of a spherical shape, a lump shape, a rod shape, a flat shape, and the like may be used. Moreover, there is no restriction | limiting in particular also about the hardness, specific gravity, a color, etc. These series of particles may be used in combination of two or more if necessary.

  Moreover, it is preferable that the average particle diameter of the particle | grains used in this invention is the range of 0.1-5 micrometers, More preferably, it is 0.5-3 micrometers, Most preferably, it is the range of 0.5-2 micrometers. If the average particle size is less than 0.1 μm, the particles tend to aggregate and the dispersibility in the film may be insufficient. On the other hand, if it exceeds 5 μm, the surface roughness of the film The degree becomes too rough, and a problem may occur when a release layer is provided in a later process.

  The content of particles in the polyester preferably satisfies the range of 0.01 to 5% by weight, more preferably 0.01 to 3% by weight. When the particle content is less than 0.01% by weight, the slipperiness of the film may be insufficient. On the other hand, when the content exceeds 5% by weight, the smoothness of the film surface is poor. It may be enough.

  The method for adding particles to the polyester is not particularly limited, and a conventionally known method can be adopted. For example, it can be added at any stage for producing the polyester, but the polycondensation reaction may proceed preferably after the esterification stage or after the transesterification reaction. Also, a method of blending a slurry of particles dispersed in ethylene glycol or water with a vented kneading extruder and a polyester raw material, or a method of blending dried particles and a polyester raw material using a kneading extruder Etc.

  The thickness of the polyester film constituting the release film of the present invention is preferably a thin film in order to reduce the influence of the film's waist, particularly when considering the point of light release of the release property to the green sheet. . However, on the one hand, it is necessary to ensure film flatness at the time of release layer lamination described later, and when the thickness of the polyester film constituting the release film is too thin, the film flatness is impaired by thermal wrinkles or the like. There are many cases.

  From such a viewpoint, the thickness of the polyester film constituting the release film in the present invention is preferably 9 to 38 μm, and more preferably 9 to 30 μm.

  For the purpose of use, it is preferable to suppress the film thickness unevenness in the longitudinal direction and the width direction of the polyester film constituting the release film in the present invention to 5% or less, more preferably, the film thickness unevenness in both the longitudinal direction and the width direction. 3% or less. As a specific method for suppressing the film thickness unevenness within the above-described range, for example, a method of employing a simultaneous biaxial stretching method is exemplified. Regarding film thickness unevenness, if at least one of the film thickness unevenness exceeds 5% in the longitudinal direction or the width direction, when a green sheet is formed using a release film composed of the polyester film, the resulting green sheet is thick The unevenness tends to increase, and may be inappropriate for manufacturing a high-capacity ceramic multilayer capacitor having 400 or more green sheets stacked, for example.

Next, although the manufacture example of the polyester film in this invention is demonstrated concretely, it is not limited to the following manufacture examples at all.
First, the polyester raw material described above is used, and the molten sheet extruded from the die is cooled and solidified with a cooling roll to obtain an unstretched sheet. In this case, in order to improve the flatness of the sheet, it is preferable to improve the adhesion between the sheet and the rotary cooling drum, and an electrostatic application adhesion method and / or a liquid application adhesion method is preferably employed. Next, the obtained unstretched sheet is stretched in the biaxial direction. In that case, first, the unstretched sheet is stretched in one direction by a roll or a 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. Subsequently, the extending | stretching temperature orthogonal to the extending | stretching direction of the 1st step is 130-170 degreeC normally, and a draw ratio is 3.0-7 times normally, Preferably it is 3.5-6 times. Subsequently, heat treatment is performed at a temperature of 180 to 270 ° C. under tension or under relaxation within 30% to obtain a biaxially oriented film.

  In the above-described stretching, a method in which stretching in one direction is performed in two or more stages can be employed. In that case, it is preferable to carry out so that the draw ratios in the two directions finally fall within the above ranges. It is also possible to perform simultaneous biaxial stretching. The simultaneous biaxial stretching method is a method in which the unstretched sheet is usually stretched and oriented in the machine direction and the width direction at 70 to 120 ° C., preferably 80 to 110 ° C., and the stretching ratio is as follows. Is 4 to 50 times, preferably 7 to 35 times, and more preferably 10 to 25 times in terms of area magnification. Subsequently, heat treatment is performed at a temperature of 170 to 250 ° C. under tension or under relaxation within 30% to obtain a stretched oriented film.

  As for the simultaneous biaxial stretching apparatus using the above-described stretching method, a conventionally known stretching method such as a screw method, a pantograph method, a linear drive method, or the like can be adopted.

  In the present invention, when the polyester film constituting the release film is stretched by simultaneous biaxial stretching, conventionally, when the area magnification becomes large by sequential biaxial stretching, a problem such as breaking at the time of stretching occurs. However, since the film following property is good in the simultaneous biaxial stretching, the area magnification can be further increased in the film longitudinal direction and the width direction as compared with the sequential biaxial stretching. It is preferable because a polyester film having a small thickness can be produced.

  In addition, a so-called coating stretching method (in-line coating) for treating the film surface during the above-described stretching process of the polyester film can be performed. Although it is not limited to the following, for example, in the sequential biaxial stretching, in particular, the first-stage stretching is completed, and the coating treatment can be performed before the second-stage stretching. When a coating layer is provided on a polyester film by a coating stretching method, coating can be performed simultaneously with stretching and the thickness of the coating layer can be reduced according to the stretching ratio. Can be manufactured.

Next, formation of the release layer of the present invention will be described.
The release layer constituting the release film in the present invention may be provided on the polyester film by the above-described coating stretching method (in-line coating), but a so-called off-line coating that is applied outside the system on the film once produced. It may be adopted, but it is preferable.

  The release layer constituting the release film in the present invention is not particularly limited as long as it has releasability, and among them, by containing a curable silicone resin, the releasability is particularly good. It will be good.

  As the type of the curable silicone resin, any of the curing reaction types such as an addition type, a condensation type, an ultraviolet curable type, an electron beam curable type, and a solventless type can be used. Among these, the addition type is preferable in terms of fast curing reaction, and among the addition types, the ultraviolet curing type, the electron beam curing type, and the solventless type are preferable because they can be cured at a lower temperature. Further, a release control agent may be used in combination in order to adjust the release property of the release layer.

  The inventors of the present invention are effective in reducing the thickness of the release layer as one of the methods for realizing light release in the release process employing the surface release method for the release layer constituting the release film. I found out. It is considered that as the release layer becomes thinner, the rigidity of the obtained release surface increases, which greatly contributes to the releasability when the green sheet is peeled off.

Therefore, regarding the release layer constituting the release film in the present invention, the coating amount of the release layer (after drying) (Si) needs to be in the range of 0.01 to 0.10 g / m ² , preferably Is 0.01 to 0.08 g / m ² , more preferably 0.01 to 0.06 g / m ² . When Si is less than 0.01 g / m ² , the coating property is lacking in stability and it becomes difficult to obtain a uniform coating film. On the other hand, when Si exceeds 0.10 g / m < ² >, in the peeling process which employ | adopts a surface peeling system, troubles, such as becoming difficult to peel, will arise.

  In the present invention, conventionally known coating methods such as reverse gravure coating, direct gravure coating, bar coating, and die coating can be used as a method of providing a release layer on the polyester film. As for the coating method, there is an example described in “Coating Method” published by Yoji Harasaki in 1979.

  In the present invention, the curing conditions for forming the release layer are not particularly limited. For example, when the release layer is provided on the polyester film by off-line coating, it is usually 3 to 40 at 80 to 200 ° C. The heat treatment may be performed for 2 seconds, preferably 100 to 180 ° C. for 3 to 40 seconds.

  Further, if necessary, heat treatment and active energy ray irradiation such as ultraviolet ray irradiation may be used in combination. In this case, a conventionally known apparatus or energy source is used as an energy source for curing by active energy ray irradiation. be able to. Specific examples include germicidal lamps, ultraviolet fluorescent lamps, carbon arcs, xenon lamps, high pressure mercury lamps for copying, medium or high pressure mercury lamps, ultra high pressure mercury lamps, electrodeless lamps, metal halide lamps, ultraviolet light using natural light as a light source, or Examples include a method using an electron beam by a scanning type or curtain type electron beam accelerator. Moreover, in the hardening by active energy ray irradiation, it is also possible to irradiate in inert gas atmosphere, such as nitrogen gas, at the point of reaction efficiency improvement.

  The polyester film constituting the release film in the present invention may be subjected to surface treatment such as corona treatment or plasma treatment in advance.

  Furthermore, the polyester film constituting the release film in the present invention may be provided with a coating layer such as an adhesive layer and an antistatic layer in advance.

  In the present invention, the surface peeling method is regarded as a peeling method in a high-speed peeling region having a higher peeling propagation speed, and in particular, the peeling force in the peeling speed region of 30 m / min or more can be lightly peeled. It was found to be important in designing possible release films. That is, in the release film according to the present invention, in order to correspond to the peeling process adopting the surface peeling method, the ratio of peeling force at different peeling speeds (F (300 m / min) / F (30 m / min)) is 2. 0.0 or less, preferably 1.5 or less. When F (300 m / min) / F (30 m / min) exceeds 2.0, it becomes difficult to peel off the green sheet after molding.

As a specific method for satisfying the above relationship, the properties of the release layer of the release film in the present invention include, for example, when the release layer contains a curable silicone resin, as a constituent unit of the release layer, a T unit. _Examples thereof include a method in which a silicone compound having a (SiO _3/2 ) structure is used in combination. Furthermore, specific examples of the silicone compound having a T unit include a solvent-type silicone resin having a branched structure or a solvent-free silicone resin having a branched structure.

  By using a silicone compound having a T unit structure in the release layer constituting the release film in the present invention, in the release layer forming process, the binder resin side (for example, the above-mentioned branch) is formed. It is possible to intentionally increase the number of crosslinking points in the crosslinking reaction from the use of a curable silicone resin having a structure. As a result, by further improving the crosslink density of the obtained release layer itself, a release step employing a surface release method, for example, after forming a sheet-like ceramic green sheet used in manufacturing a ceramic multilayer capacitor, It becomes possible to deal with a process of peeling from the release surface.

  Moreover, regarding the release film in the present invention, the peeling force (F (300 m / min)) between the release layer surface and the acrylic pressure-sensitive adhesive tape at a peeling speed of 300 (m / min) is 200 mN / cm or less, further 150 mN. / Cm or less is preferable. When F (300 m / min) exceeds 200 mN / cm, it may be difficult to peel off the green sheet. When the release film of the present invention satisfies the above additional requirements at the same time, further light peeling can be achieved in the peeling process employing the surface peeling method.

  Furthermore, in the release film of the present invention, in order to ensure the flatness of the release surface, the maximum roughness of the release surface (P-V (Si)) is preferably 700 nm or less, more preferably 500 nm or less, Particularly preferably, it is 300 (nm) or less. When PV (Si) exceeds 700 nm, the flatness of the release surface becomes insufficient, and for example, it may be difficult to obtain a green sheet having a flat surface. The lower limit of PV (Si) is preferably 50 nm in consideration of the winding property or transportability of the release film.

  Furthermore, in the release film of the present invention, the maximum roughness of the surface where no release layer is provided in order to improve the film winding property or transportability on the back surface (the surface where the release layer is not provided). (PV) preferably satisfies 300 nm or more. On the other hand, regarding the upper limit of PV, after winding up the release film on which the green sheet is laminated, 700 nm is taken into consideration in consideration of roughness transfer from the surface where the release layer is not provided to the surface of the green sheet. The upper limit is preferable.

  Regarding the release film in the present invention, the residual adhesion rate of the release layer is preferably 90% or more, more preferably 95% or more in order to suppress the migration or transfer of the release component to the green sheet surface to be molded. . When the residual adhesion rate is less than 90%, the release component moves to the surface of the counterpart green sheet that comes into contact with the release surface of the release film. For example, the adhesive strength between sheets decreases when the green sheets are laminated. May occur.

  The release film of the present invention provides a release film that can be applied to a peeling process employing a so-called surface peeling method, in which a green sheet is peeled from a release surface in the vertical direction by vacuum suction or the like. Extremely expensive.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded. The measuring method used in the present invention is as follows.

(1) Measurement of intrinsic viscosity of polyester 1 g of polyester from which other polymer components and pigments incompatible with polyester have been removed are precisely weighed, and 100 ml of a mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio) is added. It was dissolved and measured at 30 ° C.

(2) Measurement of average particle size (d ₅₀ : μm) Integration (weight basis) in equivalent spherical distribution measured using centrifugal sedimentation type particle size distribution measuring device (Shimadzu Corporation SA-CP3 type) The value of 50% was taken as the average particle size.

(3) Evaluation of release film release force (F) Adhesive tape (Nitto Denko “No. 31B”) was applied to the release layer of the sample film, then cut to a size of 50 mm × 300 mm and brought to room temperature. Measure the peel force after standing for 1 hour. For the peeling force, a tensile tester (“Intesco model 2001 type” manufactured by Intesco Co., Ltd.) was used, and 180 ° peeling was performed under a tensile speed of 0.3 m / min.

(4) Evaluation of release film release force (F (30 m / min), F (300 m / min)) After sticking an adhesive tape (“Nitto Denko“ No. 31B ”) to the release layer surface of the sample film , Cut to a size of 50 mm x 300 mm, and measure the peel force after standing at room temperature for 1 hour. The peeling force was measured using a tester industry (manufactured by) high-speed peeling tester “TE-702 type”. In the method of peeling the 31B adhesive tape side, 180 ° peeling was performed under the conditions of peeling speeds of 30 m / min and 300 m / min, respectively.

(5) Evaluation of release film peeling force (F (H)) (substitute evaluation of surface peeling force measurement)
A resin sheet made of the following resin composition was applied to the release surface of the sample film in a wet state at a coating amount of 150 (g / m ² ), and then dried in a hot air oven at 120 ° C. for 1 minute. A laminated film in which a resin sheet having a thickness (after drying) of 5 g / m ² was laminated was obtained. Next, after cutting out the obtained laminated film into a 40 mm square, using a stainless steel flat plate jig (size: 50 mm square, thickness 1 mm), Nitto Denko no. Affixed using 502 double-sided adhesive tape. Next, in the laminated film with the jigs attached on both sides, the resin sheet surface side is fixed to “Intesco Model 2001” manufactured by Intesco Co., Ltd. in a direction perpendicular to the film surface of the laminated film. The resin sheet was peeled from the release surface at a peeling speed of 400 mm / min. Using the peeling success rate (%) after repeating the same operation 10 times, the determination was made according to the following criteria. In addition, it was determined as “successful peeling” only when the resin sheet peeled from the release surface of the sample film. In the case of partial peeling or difficulty in peeling, the judgment was made as “unsuccessful peeling”.

<Resin sheet composition>
・ Polyvinyl butyral resin (Sekisui Chemical S-REC BM-S) 20 parts ・ Dioctyl phthalate 5 parts ・ Toluene / ethanol (mixing ratio 6: 4) 100 parts

<Criteria>
○ ... Peeling success rate of 90% or more (a level that is not problematic for practical use)
Δ: Peeling success rate of 70% or more and less than 90% (a level that may cause a practical problem)
×: Peeling success rate of 50% or more and less than 70% (practical problem level)
XX ... Peeling success rate is less than 50% (practically problematic level)

(6) Maximum roughness (P-V (Si), PV) evaluation of the release film and the release-layer surface of the release film Utilizing direct phase detection interferometry, so-called Michelson interference The maximum roughness (PV (Si)) of the release surface of the sample film and the release layer are provided by the non-contact surface measurement system “Micromap 512” using the two-beam interference method. The maximum roughness (P-V) of the uncoated surface was measured. The measurement wavelength was 554 nm, the objective lens was 20 times using 20 magnifications, and the average value was adopted.

(7) Measurement of release layer coating amount (Si) Using a fluorescent X-ray measurement device (Shimadzu Corporation, model “XRF-1500”) by the FP (Fundamental Parameter Method) method, the following measurement conditions The amount of silicon element on the surface of the release film provided with the release layer and the surface without the release layer was measured, and the difference was taken as the amount of silicon element in the release layer. Next, the coating amount (Si) (g / m ² ) as a unit of —SiO (CH ₃ ) ₂ was calculated using the obtained amount of silicon element.

"Measurement condition"
Spectral crystal: PET (pentaerythritol)
2θ: 108.88 °
Tube current: 95 mA
Tube voltage: 40 kv

(8) Evaluation of residual adhesion rate of release film (i) Residual adhesion strength Nitto Denko (manufactured) No. The 31B adhesive tape is subjected to one reciprocating pressure bonding with a 2 kg rubber roller, and heat-treated at 100 ° C. for 1 hour. Next, no. The 31B pressure-sensitive 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 is the residual adhesive strength.

(Ii) Basic adhesive strength Using the same adhesive tape (No. 31B) as the residual adhesive strength, press the adhesive tape on the stainless steel plate according to JIS-C-2107, and measure in the same manner. . The value at this time is defined as the basic adhesive strength. Using these measured values, the residual adhesion rate is determined based on the following equation.
Residual adhesion rate (%) = (residual adhesive force / basic adhesive force) × 100
The measurement is performed at 20 ± 2 ° C. and 65 ± 5% RH.

(9) Measurement of film thickness unevenness in the longitudinal direction and the width direction of the release film A sample film is cut into 30 mm width × 3 m length. Then, it measured with the continuous film thickness measuring device (electronic micrometer use) by Anritsu Electric Co., Ltd., and calculated film thickness nonuniformity by the following formula.
Unevenness of thickness (%) = (maximum thickness−minimum thickness) / average thickness × 100
For example, when the sample sample is an A4 cut size, the samples cut into a width of 30 mm can be joined together, and measurement can be performed in a manner of securing a measurement length of 3 m (excluding the joining portion).

(10) Evaluation of thickness unevenness of ceramic green sheet A ceramic layer having the following composition is coated on the mold release surface of the sample film using a slot die so that the thickness becomes 12 μm in a wet state by a known method. The ceramic green sheet was prepared, and the thickness of the ceramic green sheet was measured with the non-contact β-ray thickness meter on the film in the vertical and horizontal directions. Judgment was made based on the judgment criteria.

<Ceramic slurry composition>
Ceramic powder (barium titanate) 100 parts Binder (polyvinyl butyral resin) 5 parts Plasticizer (dioctyl phthalate) 1 part Toluene / MEK mixed solvent (1: 1 mixing ratio) 100 parts

<Green sheet thickness unevenness criteria>
○: Unevenness of thickness is less than 3% (a level with no practical problem)
×: Thickness unevenness of 3% or more (practically problematic level)

<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 subjected to a transesterification reaction at about 250 ° C. for 4 hours. Add 0.03 part of antimony trioxide, 0.01 part of phosphoric acid, 0.2 part of aluminum oxide particles with an average particle size of 0.2 μm, gradually raise the temperature from 250 ° C. to 285 ° C. and gradually reduce the pressure. 0.5 mmHg. After 4 hours, the polymerization reaction was stopped to obtain polyethylene terephthalate A1 having an intrinsic viscosity of 0.65.

Production Example 2 (Polyethylene terephthalate A2)
In Production Example 1, polyethylene oxide is produced in the same manner as in Production Example 2 except that 0.1 part of silicon dioxide particles having an average particle diameter of 1.5 μm is used instead of 0.2 part of aluminum oxide particles having an average particle diameter of 0.2 μm. Terephthalate A2 was obtained.

Production Example 3 (Polyethylene terephthalate A3)
In Production Example 1, instead of using 0.2 parts of aluminum oxide particles having an average particle diameter of 0.2 μm, 0.2 parts of calcium carbonate particles having an average particle diameter of 0.7 μm are used, and the production is performed in the same manner as in Production Example 2, Polyethylene terephthalate A3 was obtained.

Production Example 4 (polyethylene terephthalate A4)
In Production Example 1, polyethylene oxide is produced in the same manner as in Production Example 1, except that 1 part of aluminum oxide particles having an average particle diameter of 0.2 μm is used instead of 0.2 part of aluminum oxide particles having an average particle diameter of 0.2 μm. Terephthalate A4 was obtained.

Production Example 5 (polyethylene terephthalate A5)
In Production Example 2, polyethylene terephthalate A5 was produced in the same manner as in Production Example 1 except that 0.1 part of silicon dioxide particles having an average particle diameter of 1.5 μm was used instead of 4 parts of silicon dioxide particles having an average particle diameter of 1.5 μm. Got.

<Manufacture of polyester film>
Production Example 6 (PET film F1)
The polyethylene terephthalate A1 produced in Production Example 1 was dried at 180 ° C. for 4 hours in an inert gas atmosphere, melted at 290 ° C. by a melt extruder, extruded from a die, and the surface temperature was adjusted to 40 using an electrostatic application adhesion method. The sheet was cooled and solidified on a cooling roll set to ° C. to obtain an unstretched sheet. Next, after applying a coating agent having the following composition, the film was guided to a tenter, and simultaneously biaxially stretched 4.5 times in the longitudinal direction and 4.8 times in the transverse direction at 90 ° C., and then heated at 230 ° C. Fixing was performed to obtain a PET film F1 having a thickness of 38 μm.

Production Example 7 (PET film F2)
In Production Example 6, a PET film F2 having a thickness of 38 μm was obtained in the same manner as in Production Example 6 except that polyethylene terephthalate A2 produced in Production Example 2 was used instead of polyethylene terephthalate A1.

Production Example 8 (PET film F3)
In Production Example 6, a PET film F3 having a thickness of 38 μm was obtained in the same manner as in Production Example 6 except that polyethylene terephthalate A3 produced in Production Example 3 was used instead of polyethylene terephthalate A1.

Production Example 9 (PET film F4)
The polyethylene terephthalate A1 produced in Production Example 1 was dried at 180 ° C. for 4 hours in an inert gas atmosphere, melted at 290 ° C. by a melt extruder, extruded from a die, and the surface temperature was adjusted to 40 using an electrostatic application adhesion method. The sheet was cooled and solidified on a cooling roll set to ° C. to obtain an unstretched sheet. Next, the film was stretched 3.5 times in the longitudinal direction at 85 ° C. Thereafter, the film was guided to a tenter and stretched 3.8 times in the lateral direction, and then heat-fixed at 230 ° C. to obtain a PET film F4 having a thickness of 38 μm.

Production Example 10 (PET film F5)
In Production Example 9, a PET film F5 having a thickness of 38 μm was obtained in the same manner as in Production Example 9 except that polyethylene terephthalate A4 produced in Production Example 2 was used instead of polyethylene terephthalate A1.

Production Example 11 (PET film F6)
In Production Example 9, a PET film F6 having a thickness of 38 μm was obtained in the same manner as in Production Example 9 except that polyethylene terephthalate A5 produced in Production Example 4 was used instead of polyethylene terephthalate A1.

A release agent having the following composition was applied to the PET film F1 obtained in Production Example 4 by a gravure coating method so that the coating amount (after drying) was 0.06 g / m ² and heat-treated at 120 ° C. for 30 seconds. Later, a release film was obtained.
<Releasing agent composition>
Curing type silicone resin (manufactured by Shin-Etsu Chemical: KS-774) 49.5% by weight
Curable silicone resin (X-62-1387, manufactured by Shin-Etsu Chemical) 49.5% by weight
Curing agent (manufactured by Shin-Etsu Chemical: PL-50T) 1% by weight
The mixture was diluted with a toluene / MEK mixed solvent (mixing ratio was 1: 1) to prepare a coating solution having a solid content concentration of 2% by weight.

  In Example 1, it manufactured like Example 1 except using PET film F2 instead of PET film F1, and obtained the release film.

  In Example 1, it manufactured like Example 1 except having used PET film F3 instead of PET film F1, and obtained the release film.

  In Example 1, it manufactured like Example 1 except having used PET film F4 instead of PET film F1, and obtained the release film.

  In Example 1, it manufactured like Example 1 except having used PET film F5 instead of PET film F1, and obtained the release film.

  In Example 1, it manufactured like Example 1 except having used PET film F6 instead of PET film F1, and obtained the release film.

A release film was obtained in the same manner as in Example 1 except that the release agent composition was changed to the following release agent composition in Example 1.
<Releasing agent composition>
Curable silicone resin (manufactured by Shin-Etsu Chemical: KS-774) 64.5% by weight
Curable silicone resin (manufactured by Shin-Etsu Chemical: X-62-1387) 34.5% by weight
Curing agent (manufactured by Shin-Etsu Chemical: PL-50T) 1% by weight
The mixture was diluted with a toluene / MEK mixed solvent (mixing ratio was 1: 1) to prepare a coating solution having a solid content concentration of 2% by weight.

  In Example 1, it manufactured like Example 1 except having used Diafoil T300 (thickness 30 micrometers) by Mitsubishi Chemical Polyester Film Co. instead of PET film F1, and obtained the release film.

(Comparative Example 1)
In Example 1, it manufactured like Example 1 except the application thickness (after drying) of a release layer having been 0.12 g / m < ² >, and the release film was obtained.

(Comparative Example 2)
A release film was obtained in the same manner as in Example 1 except that the release agent composition was changed to the following release agent composition in Example 1.

<Releasing agent composition>
Curable silicone resin (manufactured by Shin-Etsu Chemical: KS-774) 99% by weight
Curing agent (manufactured by Shin-Etsu Chemical: PL-50T) 1% by weight
The mixture was diluted with a toluene / MEK mixed solvent (mixing ratio was 1: 1) to prepare a coating solution having a solid content concentration of 2% by weight.

(Comparative Example 3)
In Example 1, it manufactured like Example 1 except the application thickness (after drying) of a release layer having been 0.004 g / m < ² >, and the release film was obtained. The obtained release film was confirmed to be repelled on the release surface, and had a practically problematic level.
The obtained results are summarized in Tables 1 to 4 below.

  For example, the film of the present invention peels off the green sheet in the vertical direction by vacuum suction or the like from the release surface of the release film, for example, for forming a green sheet used in the production of ceramic electronic components such as ceramic multilayer capacitors and ceramic substrates. Therefore, it can be suitably used as a release film that can cope with a peeling process employing a so-called surface peeling method.

Claims (1)

It is a film having a release layer containing a silicone compound having a T unit (SiO _3/2 ) structure on one surface of a polyester film, and simultaneously satisfies the following formulas (1) and (2) A release film for forming green sheets.
F (300 m / min) / F (30 m / min) ≦ 2.0 (1)
0.01 ≦ Si ≦ 0.10 (2)
(In the above formula, F (300 m / min) and F (30 m / min) are release films, and the release force between the release layer surface and the acrylic pressure-sensitive adhesive tape at release rates of 300 m / min and 30 m / min, respectively ( mN / cm), Si represents the thickness (g / m ² ) of the release layer.