JP2005313601A - Mold releasing film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold releasing film enabling effective manufacture of a ceramic green sheet, a not more than 3 μm thick ceramic green sheet in particular and showing excellent adhesion between a base film and the mold releasing film even without an anchor coat layer. <P>SOLUTION: The mold releasing film has a silicone-based resin film on at least one surface of the base film, and the film contains a silicone compound obtained by reacting a silicone oil having a hydroxyl group with an isocyanate compound represented by formula (1) wherein n is an integer of 1 to 3, and R is an alkyl group or an ester group and/or a ketone group and/or an alkyl group having a hydroxyl group or an aralkyl group or an alkenyl group. The mold releasing film satisfies peeling strength of 0.1 to 8 g/50 mm and remaining adhesion of not less than 80%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a release film used in the production of ceramic green sheets. More specifically, the release film is excellent in peel strength, the amount of the release layer silicone transferred to another layer is extremely small, and even without an anchor coat layer. The present invention relates to a release film having excellent adhesion between a base film and a release layer.

  In recent years, a release film in which a heat or ultraviolet curable silicone resin film is provided as a release layer on a plastic film is generally used as a process carrier film when manufacturing ceramic green sheets for ceramic capacitors and the like. ing.

  The ceramic green sheet comprises a polymer binder such as polymethyl methacrylate, polyvinyl acetal, polyvinyl butyral, polyvinyl alcohol, a plasticizer, and a dispersant in an aqueous or organic solvent in which ceramic powder such as barium titanate or alumina is dispersed. It is generally manufactured by mixing and dispersing the added material with a high-speed mixer or a ball mill, applying the obtained ceramic slurry onto a release film by a doctor blade method, drying it and winding it.

  In recent years, in order to realize a small and high capacity multilayer ceramic chip capacitor, it has been demanded that the thickness of one ceramic layer be made thinner and multilayered, and for this purpose, it is very thin of 3 μm or less. The ceramic capacitor film is released from the release film accurately and without missing, and the transfer of foreign matter from the release film to the ceramic green sheet is reduced as much as possible to improve the lamination adhesion of the sheet. This is necessary to stabilize the capacitance of the multilayer multilayer ceramic capacitor and to reduce the withstand voltage failure rate of the multilayer multilayer ceramic capacitor.

  For this purpose, the thickness uniformity and surface smoothness of the plastic film used in the release film, light release and durability of the release surface, and adhesion between the base film and the release layer are important. It becomes.

In order to improve the light release property of the release surface, a method using a silicone resin in which a crosslinking reaction is performed by an addition reaction (for example, Patent Document 1) or a method using an isocyanate silane compound as a main element for film formation (for example, There is a patent document 2). Moreover, there exists a method of providing an adhesive layer between a base film and a mold release layer for the improvement of the adhesiveness of a base film and a mold release layer (for example, patent document 3).
JP 11-300719 A (paragraphs [0008] to [0058]) JP-A-9-141799 (paragraphs [0006] to [0048]) JP-A-5-194768 (paragraphs [0008] to [0042])

  However, with the thinning of the ceramic green sheet, as described above, when the release treatment of the release film is changed in order to improve the light release property of the release surface, the release agent for the ceramic green sheet surface, that is, silicone Part of the resin-based resin film is transferred, so that the adhesion strength between the sheets at the time of lamination of the ceramic green sheet is insufficient, or a part of the silicone-based resin film transferred as described above is laminated on the ceramic green sheet. Since bubbles are generated inside the ceramic capacitor in the subsequent firing step, the withstand voltage failure rate of the multilayer ceramic capacitor is significantly increased, which is not preferable. Furthermore, when an isocyanate silane compound is used as a main element for film formation, there is also a problem that the coating liquid is easily deteriorated. Moreover, in order to improve the adhesiveness of a base film and a release layer, an anchor coat layer may be provided between both layers, but there exists a problem that productivity is low and cost becomes high.

  The present invention solves the above-mentioned problems, and can efficiently produce a ceramic green sheet, particularly a thin ceramic green sheet of 3 μm or less, and the adhesion between the base film and the release layer can be achieved without an anchor coat layer. An object is to provide an excellent release film for producing a ceramic green sheet.

In order to solve the above problems, the present invention has the following configuration. That is,
[1] A release layer composed of a silicone resin film is provided on at least one surface of a base film, and the silicone resin film is obtained by reacting a silicone oil having a hydroxyl group with an isocyanate compound of the following formula (1). A release film comprising a silicone compound, wherein the release film satisfies a characteristic range in which a peel strength of the release film is 0.1 to 8 g / 50 mm and a residual adhesion rate is 80% or more. the film.

(In the formula, n represents an integer of 1 to 3, R represents an alkyl group, an ester group and / or a ketone group and / or a hydroxyl group having a hydroxyl group, an aralkyl group or an alkenyl group).
[2] The release film as described in [1] above, wherein the silicone resin film has a urethane structure.
[3] The release film as described in [1] or [2] above, wherein the center line average surface roughness (Ra) on the silicone resin film surface is 5 to 60 nm.
[4] The silicon element strength A (unit: kcps) measured by the fluorescent X-ray method of the silicone-based resin film satisfies the following formula (2), according to any one of the above [1] to [3] Release film.

5 ≦ A ≦ 40 (2) Formula [5] In the above [1] to [4], the base film is any one of a polyester film, a polyolefin film, a polyphenylene sulfide film, and a nylon film. The release film in any one.
[6] The polyester film is any one of a polyethylene terephthalate film, a polyethylene-2,6-naphthalate film, and a polyethylene-α, β-bis (2-chlorophenoxy) ethane-4,4′-dicarboxylate film. The release film as described in [5] above, wherein
Consists of.

  By using the release film of the present invention, while satisfying the peelability of the ceramic green sheet, the silicone-based resin film is transferred to the ceramic green sheet, that is, the release film is rolled and stored. In this case, it is possible to satisfy the conflicting property that a part of the silicone-based resin film can be very little transferred to the back side of the release film. In particular, it is possible to extremely reduce the generation of bubbles in the ceramic capacitor in the process of firing after laminating a thin ceramic green sheet of 3 μm or less, and the breakdown voltage failure rate of the multilayer ceramic capacitor can be greatly improved. .

  Furthermore, according to the present invention, it is not necessary to provide an anchor coat layer between both layers in order to improve the adhesion between the base film and the release layer, and the productivity of the release film can be improved.

  Furthermore, by using the release film of a more preferable aspect of the present invention, there is no poor adhesion between the ceramic green sheet constituting the ceramic capacitor and the internal electrode, and no misalignment occurs when the sheets are laminated. Furthermore, it is possible to eliminate non-uniformity in capacitance due to local stress concentration in the subsequent pressurizing step.

  Examples of the base film of the present invention include synthetic polymer films (including sheets) such as polyester films, polyolefin films, polyphenylene sulfide films, and nylon films. Of these, polyester is preferable, and among them, polyethylene terephthalate film, polyethylene 2,6-naphthalate film, and polyethylene-α, β-bis (2-chloro), which are excellent in heat resistance, surface characteristics, and the like. Phenoxy) ethane-4,4′-dicarboxylate film is preferred, in particular, biaxially oriented polyethylene terephthalate film, biaxially oriented polyethylene 2,6-naphthalate film, and biaxially excellent in mechanical strength and dimensional stability. An oriented polyethylene- [alpha], [beta] -bis (2-chlorophenoxy) ethane-4,4'-dicarboxylate film is preferred.

  The base film constituting the present invention is produced by a conventional method, and in particular, biaxially oriented polyethylene terephthalate film, biaxially oriented polyethylene 2,6-naphthalate film, and biaxially oriented polyethylene-α, β- The film thickness of the bis (2-chlorophenoxy) ethane-4,4′-dicarboxylate film is in the range of 15 to 350 μm, preferably 20 to 100 μm in terms of mechanical properties, dimensional stability, heat resistance, price, etc. Preferably applied.

Moreover, when the fish eye value of the base film by the SI-BPM method is 0 to 20 pieces / 1000 cm ² , the sheet when the thin ceramic green sheet of 3 μm or less is peeled from the release film using the film is used. It is desirable because tears are extremely low. The SI-BPM method is a measurement method that utilizes interference of reflected light due to the presence of fish eyes when the film is overlaid and exposed to light.

  The silicone-based resin film in the present invention includes a polyorganosiloxane having a structure represented by the following formula (3) as a main component, and includes a silicone compound obtained by reacting a silicone oil having a hydroxyl group with an isocyanate compound, The polyorganosiloxane, the silicone oil, and the isocyanate compound are crosslinked to form a film. In particular, a silicone-based resin film in which the cross-linking reaction is performed in an addition reaction type is preferable in order to clarify the objects and effects of the present invention.

(In the formula, R1 represents a methyl group and a phenyl group, and V1 represents a hexenyl group and a vinyl group).

  As the silicone oil having a hydroxyl group in the silicone resin film, for example, trade names of BY16-201, BY16-848, BY16-005, BY16-007, SF8427, SF8428, manufactured by Toray Dow Corning Silicone Co., Ltd., or , Shin-Etsu Chemical Co., Ltd. trade names are X-22-160AS, KF-6001, KF-6002, KF-6003, X-22-4015 oils, and the like.

  The isocyanate compound in the silicone resin film is a compound having a general structural formula represented by the following formula (1), or a polyisocyanate compound having a blocked or unblocked isocyanate group.

(In the formula, n represents an integer of 1 to 3, and R represents an alkyl group, an ester group and / or a ketone group, and / or an alkyl group having a hydroxyl group, an aralkyl group, or an alkenyl group).

  In the silicone resin film, a compound having a urethane structure is obtained by reacting a silicone oil having a hydroxyl group with an isocyanate compound. The urethane structure which is a preferable embodiment included in the silicone resin film is, for example, It is a structure shown by (4) Formula.

(In the formula, R and R 'each represents an alkyl group, an alkyl group having an ester group and / or a ketone group and / or a hydroxyl group, an aralkyl group or an alkenyl group).

  Drying and curing (thermal curing, ultraviolet curing, etc.) of the silicone resin coating can be performed individually or simultaneously. When performing simultaneously, although depending also on the heat resistance (thermal dimensional stability) of a base film, it is preferable to heat for 15 seconds or more in the temperature range of 80 to 200 degreeC, Preferably it is 120 to 180 degreeC.

Moreover, in this invention, it is preferable that the silicon element intensity | strength A (unit: kcps) by the fluorescent X ray method of a silicone type resin membrane | film | coat surface satisfies the following (2) Formula.
5 ≦ A ≦ 40 (2) formula.

  When the silicon element strength A (unit: kcps) is 5 ≦ A ≦ 40, the amount of migration of the silicone-based resin film to the release side of the ceramic green sheet after peeling is reduced, and after the ceramic green sheets are laminated This is preferable because the adhesion between the ceramic green sheets is not lowered, and pinholes are not generated in the ceramic green sheets when the ceramic green sheets are peeled off, and the ceramic green sheets are hardly broken.

  Furthermore, in the multilayer ceramic capacitor obtained from the ceramic green sheet produced using the release film having the silicon element strength within the above range, the internal electrode of the multilayer ceramic sheet is not easily short-circuited, Since the initial failure is less likely to occur, the withstand voltage failure rate is greatly reduced.

  In order to reduce the migration of the silicone-based resin film, which is a feature of the present invention, to the ceramic green sheet, the molar amount of hexenyl group or vinyl group in the polyorganosiloxane and the amount of the organohydropolyene polysiloxane are adjusted, The rubber hardness of the silicone resin film is 20 ° or less, preferably 15 ° or less. At this time, the rubber hardness of the silicone resin film is determined by mixing a predetermined amount of chloroplatinic acid reacted with polyorganosiloxane oil into the predetermined amount of polyorganosiloxane and organohydropolysiloxane, and removing the solvent under vacuum. Then, it is heated at 120 ° C. for 10 minutes to produce a sheet-like silicone resin film having a thickness of about 10 mm, and this is obtained by measuring with a JIS rubber hardness meter.

  In the present invention, the coating method when forming the silicone resin film is not particularly limited, but usually, aromatic hydrocarbons such as benzene, toluene, xylene, fatty acid hydrocarbons such as cyclohexane, n-hexane, n-heptane, Direct gravure coater, micro gravure coater, reverse using coating agent in which silicone resin is dissolved in organic solvent such as halogenated hydrocarbons such as perchloroethylene, ethyl acetate, and methyl vinyl ketone. It can be obtained by coating with a gravure coater, direct kiss coater, reverse kiss coater, comma coater, die coater, bar / lot type coating apparatus or the like.

  Among these, the use of a micro gravure coater, a direct kiss coater, or a reverse kiss coater is preferable because the uniformity of the thickness of the silicone resin film is good and the occurrence of coating unevenness is small.

  The centerline average surface roughness (Ra) on the release surface side of the release film of the present invention is preferably 5 to 60 nm with a cut-off value of 0.25 mm, more preferably 10 to 40 nm. When the center line average surface roughness is within the above range, the ceramic green sheet obtained by peeling from the release film becomes smooth and improves the adhesion between the ceramic green sheets when the ceramic green sheets are laminated. Thus, it is possible to reduce the capacitance variation of the multilayer ceramic capacitor as the final product.

Further, when the number of protrusions of 400 nm or more on the surface of the base resin film on the surface of the silicone-based resin coating is 5 or less per 0.1 mm ² , preferably 0, when the ceramic green sheet is produced, This is desirable because pinholes are reduced and the withstand voltage failure rate of multilayer ceramic capacitors is reduced.

In addition, the peeling strength of the release film of this invention needs to be 0.1-8g / 50mm, Preferably it is 1-4g / 50mm. When it is less than 0.1 g / 50 mm, the ceramic sheet or the like may be peeled off from the release film when the laminated sheet obtained by laminating the ceramic sheet or the like on the release film is taken up. If the thickness exceeds 8 g / 50 mm, peeling may be difficult when the ceramic sheet or the like is peeled from the laminated sheet.
Furthermore, the residual adhesive rate of the release film of the present invention needs to be 80% or more, and more preferably 90% or more. When the release film is less than 80%, for example, when the release film is rolled and stored, the silicone resin film component is transferred to the surface of the adjacent film, and the characteristics of the silicone resin film become poor, This is because properties such as adhesion on the surface of the adjacent film may be defective.
Moreover, the component ratio of the silicone resin for producing the release film of the present invention satisfying the characteristic range of peel strength of 0.1 to 8 g / 50 mm and residual adhesion rate of 80% or more is the structure of the above formula (3). 100 parts by mass of the polyorganosiloxane, 0.1 to 3.0 parts by mass of the silicone oil having a hydroxyl group with respect to 100 parts by mass of the polyorganosiloxane, and 100 parts by mass of the silicone oil. It is preferable to make the isocyanate compound which has a structure into the range of 5-70 mass parts.

The present invention will be specifically described with reference to examples, but the present invention is not limited thereto.
In addition, the characteristic evaluation of the ceramic green sheet produced using the release film and the release film was performed by the following method.

1) Measurement of silicon element strength by fluorescent X-ray method:
The release film is cut into a predetermined size (50 mmφ), and the silicon element strength A on the silicone resin film surface side is counted with a fluorescent X-ray apparatus under the following conditions. Next, the silicon element strength B is counted on the plastic film before applying the silicone resin film on the surface by the same condition method as described above. The value obtained by subtracting the silicon element strength B from the silicon element strength A thus obtained was defined as the silicon element strength (unit: kcps) of the silicone resin film.
・ Device name: X-ray SPECTROMETER RIX1000 manufactured by Rigaku
・ X-ray tube: Horizontal Cr target ・ Element code: Si06
-Spectral crystal: LIF1
・ Slit: SOARSE
・ Primary filter: OUT
・ Diaphragm: 30mm
・ Applied voltage, current (XG): 50kV-50mA
・ PHA: 100-350
PEAK: 2θ / 144.520 deg, time / 40 seconds BG. 1: 2θ / 143.000 deg, time / 10 seconds · BG. 2: 2θ / 146.000 deg, time / 10 seconds.

2) Peel strength:
A 200 mm long 100 mm wide release film and a polyester adhesive film (Nitto Denko 31B tape: 25 μm thickness, 50 mm width) were bonded together while being pressed with a 5 kg roller, and left for 24 hours at 20 ° C. and 65% humidity. The 180 ° peel strength was measured with a tensile tester at a peel rate of 300 mm / min. Here, it is good if the peel strength is 5 g / 50 mm or less. As described above, when the peel strength is less than 0.1 g / 50 mm, the ceramic sheet or the like may be peeled off from the release film when the laminated sheet in which the release sheet is laminated with the ceramic sheet or the like is wound. This is not preferable. On the other hand, if the peel strength exceeds 8 g / 50 mm, it may be difficult to peel the ceramic sheet or the like from the laminated sheet, which is not preferable.

3) Residual adhesion rate:
A release film with a length of 200 mm and a width of 100 mm and a polyester adhesive film (31B tape manufactured by Nitto Denko: 25 mm width) are bonded together while being pressed with a 5 kg roller and left at 40 ° C. under a load of 20 g / cm ² for 24 hours. did. Thereafter, the polyester pressure-sensitive adhesive film was peeled off, bonded to a copper plate while being pressed with a 5 kg roller, and allowed to stand for 24 hours, and then the 180 ° peel strength was measured with a tensile tester to obtain the residual adhesive strength (f). The same measurement was performed using a Teflon (registered trademark) sheet instead of a release film as a blank to obtain a basic adhesive force (f ₀ ), and a residual adhesion rate was calculated by the following equation (5). It is favorable that the residual adhesion rate is 80% or more. As described above, when the residual adhesive rate is less than 80%, for example, when the release film is rolled and stored, the silicone resin film component is transferred to the surface of the adjacent film, and the silicone resin film This is not preferable because the above-mentioned characteristics may be poor, or the characteristics such as the adhesiveness of the adjacent film surface may be poor.
- Residual adhesion ratio _{(%) = (f / f} 0) × 100 (5) formula.

4) Love-off properties:
The silicone resin film surface was rubbed 5 to 6 times with a fingertip, and the degree of dropping of the silicone resin film was judged according to the following evaluation criteria, which was used as a measure of adhesion between the base film and the silicone resin film.
○: No dropout (good adhesion)
Δ: Slightly dropped, but no problem in practical use ×: Dropped (poor adhesion)

5) Moisture resistance:
The release film was placed under the condition of 60 ° C./98% RH, and the silicone resin film surface was rubbed with the fingertip 5 to 6 times every 24 hours, and the time until the silicone resin film fell off was measured. It is preferable that the silicone resin film surface is rubbed 5 to 6 times with a fingertip and the time until the silicone resin film falls off exceeds 300 hours.

6) Solvent wear resistance:
On the silicone resin film surface, the peel strength of the silicone resin film surface was measured after reciprocating 30 times with a cloth impregnated with toluene while applying a load of 500 g / cm ^{2 with} a Gakushin abrasion tester. The peel strength is preferably 1 to 1.5 times that of a release film that has not been reciprocated 30 times with a toluene-impregnated cloth.

7) Centerline average surface roughness (unit: nm):
Based on JIS-B-0601, it was measured with a cut-off value of 0.25 mm.

8) Adhesion between ceramic green sheet and internal electrode:
A ceramic slurry having the following composition was applied onto the release layer of the release film by a doctor blade method so that the thickness after drying was 8 μm, dried, and then heated and solidified at 100 ° C. for 10 minutes, and 1 at 20 ° C. Leave for hours. Next, a conductive paste having the following composition is screen-printed on the ceramic green sheet, dried at 80 ° C. for 10 minutes to form an internal electrode, and then left at 20 ° C. for 1 hour. Next, the ceramic green sheet A on which the internal electrode is formed is peeled from the release film.
Further, in the peeled ceramic green sheet A, the 180 ° peel strength between the ceramic green sheet and the internal electrodes was measured with a tensile tester at a peel rate of 300 mm / min. When the peel strength is 1.5 kg / 15 mmφ or more, “◯”, when the peel strength exceeds 0.7 kg / 15 mmφ and less than 1.5 kg / 15 mmφ, “△”, the peel strength is 0.7 kg / 15 mmφ The following were marked with “x”. If it is (circle) and (triangle | delta), the adhesiveness of a ceramic green sheet and an internal electrode is favorable.

"Composition of ceramic slurry"
Alumina 53 parts by mass Barium oxide 8 parts by mass Silicon oxide 36 parts by mass Polyvinyl butyral 30 parts by mass Dichloroethane 80 parts by mass
"Conductive paste"
Ni-based powder 90 parts by mass Organic vehicle 10 parts by mass Terpineol 30 parts by mass.

[Example 1]
A biaxially oriented polyester film 38 μm thick “Lumirror R75” manufactured by Toray Industries, Inc. is used as a base film, and a thermosetting silicone-based resin coating is applied to one side of the base film, and the following composition A is a gravure roll ( # 200, slanted line type), dried in a 130 ° C. oven for 20 seconds, and thermally cured to obtain a release film. Further, the obtained release film was subjected to aging treatment at 60 ° C. for 3 days. The silicon element strength by fluorescent X-rays on the silicone resin film surface of the obtained release film was 20 kcps. The results are shown in Table 1, and all of mold release property, residual adhesion rate, rub-off property, moisture resistance, and solvent wear resistance were extremely good.

"Thermosetting silicone resin coating composition A"
1) Toray Dow Corning Silicone LTC750A: 20 parts by mass 2) Toray Dow Corning Silicone SRX212: 0.12 parts by mass 3) Toray Dow Corning Silicone BY16-201: 0.4 parts by mass 4) TD curing agent made by NIPPON Kako Co., Ltd .: 0.2 parts by mass 5) Toluene: 250 parts by mass 6) Methyl ethyl ketone: 30 parts by mass.

[Example 2]
A release film was obtained in the same manner as in Example 1 except that the base film was a biaxially oriented polyester film having a thickness of 38 μm, “Lumirror S28T” manufactured by Toray Industries, Inc. The silicon element strength by fluorescent X-rays on the silicone resin film surface of the obtained release film was 20 kcps. The results are shown in Table 1. All of peel strength, residual adhesion rate, rub-off property, moisture resistance, and solvent wear resistance were extremely good.

[Example 3]
A release film was obtained in the same manner as in Example 1 except that the base film was a biaxially oriented polyester film having a thickness of 38 μm, “Lumirror R58” manufactured by Toray Industries, Inc. The silicon element strength by fluorescent X-rays on the silicone resin film surface of the obtained release film was 20 kcps. The results are shown in Table 1. All of peel strength, residual adhesion rate, rub-off property, moisture resistance, and solvent wear resistance were extremely good.

[Comparative Example 1]
A release film was obtained in the same manner as in Example 1 except that the silicone-based resin coating was changed to the following composition B containing no isocyanate compound. The silicon element strength by fluorescent X-rays on the silicone resin film surface of the obtained release film was 20 kcps. The results are shown in Table 1, and were inferior in residual adhesion rate, rub-off property, moisture resistance, and solvent wear resistance.

“Thermosetting silicone” resin coating composition B
1) Toray Dow Corning Silicone LTC750A: 20 parts by mass 2) Toray Dow Corning Silicone SRX212: 0.12 parts by mass 3) Toray Dow Corning Silicone BY16-201: 0.4 parts by mass 4) Toluene: 250 parts by mass 5) Methyl ethyl ketone: 30 parts by mass.

[Comparative Example 2]
A release film was obtained in the same manner as in Example 1 except that the silicone oil in the silicone-based resin coating was used in the following composition C using silicone oil BY16-152 having a carboxy group. The silicon element strength by fluorescent X-rays on the silicone resin film surface of the obtained release film was 20 kcps. The results are shown in Table 1, but the peel strength was out of the preferred range, and the moisture resistance and solvent wear resistance were inferior.

"Thermosetting silicone resin coating composition C"
1) Toray Dow Corning Silicone LTC750A: 20 parts by mass 2) Toray Dow Corning Silicone SRX212: 0.12 parts by mass 3) Toray Dow Corning Silicone BY16-152: 0.4 parts by mass 4) Toluene: 250 parts by mass 5) Methyl ethyl ketone: 30 parts by mass.

[Comparative Example 3]
A release film was obtained in the same manner as in Example 1 except that the silicone oil of the silicone-based resin coating was used in the following composition D using silicone oil BY16-750 having a methacryloxy group. The silicon element strength by fluorescent X-rays on the silicone resin film surface of the obtained release film was 20 kcps. The results are shown in Table 1, but the peel strength was out of the preferred range, and the moisture resistance and solvent wear resistance were inferior.

"Thermosetting silicone resin coating composition D"
1) Toray Dow Corning Silicone LTC750A: 20 parts by mass 2) Toray Dow Corning Silicone SRX212: 0.12 parts by mass 3) Toray Dow Corning Silicone BY16-750: 0.4 parts by mass 4) Toluene: 250 parts by mass 5) Methyl ethyl ketone: 30 parts by mass.

[Comparative Example 4]
A release film was obtained in the same manner as in Example 1 except that the silicone-based resin coating was changed to the following composition E containing no silicone oil or isocyanate compound. The silicon element strength by fluorescent X-rays on the silicone resin film surface of the obtained release film was 20 kcps. The results are shown in Table 1. The peel strength was out of the preferred range, and the rub-off property, moisture resistance, and solvent wear resistance were inferior.

"Thermosetting silicone resin coating composition E"
1) Toray Dow Corning Silicone LTC750A: 20 parts by mass 2) Toray Dow Corning Silicone SRX212: 0.12 parts by mass 3) Toluene: 250 parts by mass 4) Methyl ethyl ketone 30 parts by mass.

[Comparative Example 5]
A release film was obtained in the same manner as in Example 1 except that the silicone resin coating composition was changed to the following composition F. The silicon element strength of the obtained release film on the silicone resin film surface by fluorescent X-rays was 4 kcps. The results are shown in Table 1, but the peel strength was out of the preferred range.

"Thermosetting silicone resin coating composition F"
1) Toray Dow Corning Silicone LTC750A: 20 parts by mass 2) Toray Dow Corning Silicone SRX212: 0.12 parts by mass 3) Toray Dow Corning Silicone BY16-201: 0.4 parts by mass 4) Toluene: 1250 parts by mass 5) Methyl ethyl ketone: 150 parts by mass.

[Example 4]
The centerline average surface roughness (Ra) measured on the release surface side of the release film obtained in Example 1 with a cutoff value of 0.25 mm based on JIS-B-0601 was 30 nm. Further, using the release film, a ceramic green sheet on which internal electrodes were formed was produced based on the evaluation item 8). Next, the adhesion between the ceramic green sheet and the internal electrode was measured. The measured results are shown in Table 2, and the adhesion was good.

[Example 5]
The centerline average surface roughness (Ra) measured on the release surface side of the release film obtained in Example 2 with a cutoff value of 0.25 mm based on JIS-B-0601 was 24 nm. Further, using the release film, a ceramic green sheet on which internal electrodes were formed was produced based on the evaluation item 8). Next, the adhesion between the ceramic green sheet and the internal electrode was measured. The measured results are shown in Table 2, and the adhesion was good.

[Example 6]
The centerline average surface roughness (Ra) measured on the release surface side of the release film obtained in Example 3 with a cut-off value of 0.25 mm based on JIS-B-0601 was 14 nm. Moreover, using the release film, a ceramic green sheet on which internal electrodes were formed was produced based on the evaluation item 8). Next, the adhesion between the ceramic green sheet and the internal electrode was measured. The measured results are shown in Table 2, and the adhesion was good.

[Example 7]
A release film was obtained in the same manner as in Example 1 except that the base film was a biaxially oriented polyester film “Lumirror E20” manufactured by Toray Industries, Inc. with a thickness of 38 μm. The centerline average surface roughness (Ra) measured on the release surface side of the obtained release film with a cutoff value of 0.25 mm based on JIS-B-0601 was 59 nm. Further, using the release film, a ceramic green sheet on which internal electrodes were formed was produced based on the evaluation item 8). Next, the adhesion between the ceramic green sheet and the internal electrode was measured. The measured results are shown in Table 2. Although the adhesion was slightly inferior, it was at a level causing no practical problems.

  If the release film of the present invention is used, it is possible to efficiently produce a ceramic green sheet with very little adhesion of the silicone-based resin. Thereby, the ceramic green sheet is laminated and then fired in the ceramic capacitor. Since bubbles are less likely to occur, the withstand voltage failure rate of ceramic capacitors is greatly improved. Furthermore, according to the present invention, it is not necessary to provide an anchor coat layer between both layers in order to improve the adhesion between the base film and the release layer, and the productivity of the release film can be improved.

  Further, by using the release film of a more preferable aspect of the present invention, there is no poor adhesion between the ceramic green sheet and the internal electrode constituting the ceramic capacitor, and no misalignment occurs when the sheets are laminated. Furthermore, it is possible to eliminate non-uniformity in capacitance due to local stress concentration in the subsequent pressurizing step.

Claims (6)

A base material film has a release layer composed of a silicone resin film on at least one surface, and the silicone resin film is obtained by reacting a silicone oil having a hydroxyl group with an isocyanate compound of the following formula (1): A release film comprising the release film, wherein the release film satisfies a characteristic range of a peel strength of 0.1 to 8 g / 50 mm and a residual adhesion rate of 80% or more.

(In the formula, n represents an integer of 1 to 3, R represents an alkyl group, an ester group and / or a ketone group and / or a hydroxyl group having a hydroxyl group, an aralkyl group, or an alkenyl group.)   The release film according to claim 1, wherein the silicone resin film has a urethane structure.   The release film according to claim 1 or 2, wherein the center line average surface roughness (Ra) of the silicone resin film surface is 5 to 60 nm. The release film according to any one of claims 1 to 3, wherein the silicon element strength A (unit: kcps) of the silicone resin film by the fluorescent X-ray method satisfies the following formula (2).
5 ≦ A ≦ 40 (2) Formula   The release film according to any one of claims 1 to 4, wherein the base film is any one of a polyester film, a polyolefin film, a polyphenylene sulfide film, and a nylon film.   The polyester film is any one of a polyethylene terephthalate film, a polyethylene-2,6-naphthalate film, and a polyethylene-α, β-bis (2-chlorophenoxy) ethane-4,4′-dicarboxylate film. The release film according to claim 5.