JPH11320524A - Release film for forming film green sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a release film which can be used for formation of a film green sheet on which blocking and the like are not generated when the release film with a flat surface release layer is taken up into the roll shape. SOLUTION: In the constitution of a release film for forming a film green sheet, the release film is provided with a release layer formed on one face of a polyester film, and the average centerline roughness Ra of the surface of the release film is 30 nm or less, and the distribution curve representing the relation between the protrusion height X of the release layer surface and the number of protrusions Y is in the range of 0.05-0.3 μm, which satisfies the formula, and the number of projections of 0.4 μm protrusion height or higher on the release layer is 35 pcs./mm<2> . The formula is log Y>=-5X. In the formula, X represents the height (μm) of the protrusion formed on the surface of the release layer and Y represents the number of protrusions (pcs./mm<2> ) on the surface of the release layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a release film, and more particularly to a release film for forming a thin film green sheet for a multilayer ceramic capacitor.

[0002]

2. Description of the Related Art Conventionally, a release film having a polyester film as a base material has been used as a carrier film for forming a green sheet for a ceramic laminated capacitor. In recent years, as the size and capacity of ceramic multilayer capacitors have increased, the thickness of the green sheet itself has also tended to decrease.

[0003] With the further reduction in the thickness of the green sheet, it is difficult to form a green sheet having a thickness of 5 µm or less, particularly with a release film having a high surface roughness of the release layer surface. In addition, when the surface roughness of the release layer surface of the release film is high, problems such as repelling of the slurry or generation of pinholes at the time of applying the ceramic slurry, and breaking of the green sheet at the time of peeling the green sheet may occur. .

[0004] When a release film using a polyester film having a low surface roughness as a base material is used to solve the above problems, blocking or wrinkling may occur when the release film is wound into a roll. Failure may occur.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a release film which can be used for forming a thin green sheet without blocking or the like even when a release film having a flat release layer surface is wound into a roll. Is to solve the problem.

[0006]

Means for Solving the Problems The inventors of the present invention have made intensive studies in view of the above-mentioned situation, and have found that the above-mentioned problems can be easily solved by providing a specific release layer, thereby completing the present invention. Reached. That is, the gist of the present invention is a release film in which a release layer is coated on one surface of a polyester film, and the center line average roughness (Ra) of the release layer surface is provided.
Is 30 nm or less, and the distribution curve representing the relationship between the projection height (X) and the number of projections (Y) on the surface of the release layer has a projection height of 0.0.
The following formula is satisfied in the range of 5 to 0.3 μm, and the number of protrusions having a protrusion height of 0.4 μm or more on the surface of the release layer is 35 / mm.
² or less, which is a release film for forming a thin green sheet.

[0007]

[Formula 3] logY ≧ −5X (where X represents the projection height (μm) on the surface of the release layer, and Y represents the number of protrusions (number / mm ² ) on the surface of the release layer).

[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 as a raw material of the polyester film may be a homopolyester or a copolyester. As the homopolyester, those obtained by polycondensing an aromatic dicarboxylic acid and an aliphatic glycol can be used. 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,
4-cyclohexanedimethanol and the like. Typical polyesters include polyethylene terephthalate (PET) and polyethylene-2,6-naphthalenedicarboxylate (PEN). On the other hand, in the case of a copolyester, a copolymer containing a third component of usually 30 mol% or less can be used. As the dicarboxylic acid component of the copolymerized polyester, one or two of isophthalic acid, terephthalic acid phthalate, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, and oxycarboxylic acid (for example, P-oxybenzoic acid) are used. The above is mentioned, and as the glycol component, one or more of ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol and the like are mentioned.

In the present invention, it is preferable to blend particles of silica, calcium carbonate, kaolin, titanium oxide, aluminum oxide and the like in the polyester. The average particle size and the amount of particles used are not particularly limited, but those having an average particle size of 0.1 to 1.0 μm are preferable, and the amount of addition is 0.1 to 1% by weight, and more preferably 0 to 1% by weight. The preferred range is from 3 to 1% by weight.

In the present invention, the center line average roughness of the polyester film surface constituting the release film is 10 to 4
A range of 0 nm is preferred. In the present invention, the method of blending the particles into the polyester is not particularly limited, and a conventionally known method can be employed. For example, it can be added at any stage during the production of the polyester, but is preferably added as a slurry dispersed in ethylene glycol or the like at the stage of esterification or after the end of the transesterification reaction and before the start of the polycondensation reaction. ,
The polycondensation reaction may proceed. 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, a method of blending dried particles with a polyester raw material using a kneading extruder, and the like. Done by

In the present invention, the thickness of the polyester film is not particularly limited as long as it can be formed as a film, but is usually in the range of 9 to 350 μm, preferably 12 to 250 μm. . Next, in the present invention, a method for producing a polyester film constituting a release film will be specifically described, but the polyester film of the present invention is not limited to the following production examples.

That is, 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 enhance 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 film is stretched biaxially to be biaxially oriented. That is, 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. Next, stretching is performed in a direction orthogonal to the stretching direction of the first stage. The stretching temperature is usually 70 to 120 ° C, preferably 80 to 11 ° C.
The stretching ratio is usually 3.0 to 7 times, and preferably 3.5 to 6 times. And then, 130-2
Heat treatment is performed at a temperature in the range of 50 ° C. under a relaxation of 30% or less to obtain a biaxially stretched film.

A so-called in-line coating for treating the film surface during the stretching step can also be applied. For example, after the first-stage stretching is completed, before the second-stage stretching, an aqueous solution, an aqueous emulsion, or an aqueous slurry is used for the purpose of improving antistatic properties, sliding properties, adhesiveness, and the like, and improving secondary workability. And the like. In the above stretching, a method in which unidirectional stretching is performed in two or more stages can also be used. In that case, it is preferable that the stretching is performed so that the stretching ratios in the two directions finally fall within the above ranges. The unstretched sheet may have an area magnification of 10 to 40.
It is also possible to perform simultaneous biaxial stretching so as to double the length.
Further, if necessary, the film may be stretched in the longitudinal and / or transverse directions again before or after the heat treatment.

Further, various stabilizers, ultraviolet absorbers, lubricants, pigments, antioxidants, plasticizers and the like may be added to the polyester film. In the present invention, the material constituting the release layer is not particularly limited as long as it has release properties, and may be a type containing a curable silicone resin as a main component, a urethane resin, an epoxy resin, an alkyd resin. For example, a modified silicone type obtained by graft polymerization with an organic resin such as the above may be used. Among them, those containing a curable silicone resin as a main component are preferable in that they have good releasability.

The type of the curable silicone resin may be any of a solvent addition type, a solvent condensation type, a solvent ultraviolet curing type, a solventless addition type, a solventless condensation type, a solventless ultraviolet ray curing type, and a solventless electron beam curing type. Reaction types can also be used. A specific example is KS-77 manufactured by Shin-Etsu Chemical Co., Ltd.
4, KS-775, KS-778, KS-779H, K
S-856, X-62-2422, X-62-246
1, KNS-305, KNS-3000, X-62-1
256, Dow Corning Asia DKQ3-2
02, DKQ3-203, DKQ3-204, DKQ3
-205, DKQ3-210, Y made by Toshiba Silicone Co., Ltd.
SR-3022, TPR-6700, TPR-672
0, TPR-6721, etc., manufactured by Dow Corning Toray Silicone Co., Ltd. SD7223, SD7226, SD722
9, SRX-210, and the like.

In the present invention, as a method of applying a release layer to a polyester film, reverse roll coating,
Conventionally known coating methods such as gravure coating and bar coating can be used. The coating amount of the release layer is preferably in the range of 0.01 to 5 g / m ² from the viewpoint of coatability to the polyester film. When the range is less than 0.01 g / m ² , stability tends to be lacking in terms of coatability, and it may be difficult to obtain a uniform coating film. On the other hand, 5 g / m ²
If the thickness exceeds the limit, the curability tends to be inferior.

Further, in the present invention, particles may be added for the purpose of preventing blocking on the surface of the release layer, improving slipperiness, and the like. The type of particles used may be either organic particles or inorganic particles, and is not particularly limited thereto. In the release film of the present invention, a coating layer such as an antistatic layer and an adhesive layer may be provided between the polyester film and the release layer or on the surface where the release layer is not provided. The polyester film may be subjected to a surface treatment such as a corona treatment and a plasma treatment in advance.

The coating layer may further contain, if necessary, organic particles, inorganic particles, an antifoaming agent, a coating improver, a thickener, an organic lubricant, an antioxidant, an ultraviolet absorber, a foaming agent, A dye or the like may be contained. The coating amount of the coating layer is not particularly limited, but is preferably in the range of 0.01 to 5 g / m ² . If it is out of the range, the same problem as in the case of the release layer described above may occur.

The center line average roughness (hereinafter abbreviated as Ra (A)) of the release layer surface of the release film of the present invention is 30 nm.
The following must be satisfied: 20 nm, and further 15 n
By setting it to m or less, it is possible to sufficiently cope with forming a thin film green sheet having a thickness of 5 μm or less. R
If a (A) exceeds 30 nm, problems such as repelling of the slurry during the application of the ceramic slurry will occur. The lower limit of Ra (A) is preferably set to 5 nm in consideration of the workability when handling the release film.

In the present invention, as a method for adjusting Ra (A) to a range of 30 nm or less, for example, a coating layer is provided in advance on a polyester film, the film surface is flattened, and then a release layer is provided. And the like. In the release film of the present invention, the distribution curve representing the relationship between the protrusion height (X) and the number of protrusions (Y) on the surface of the release layer has a protrusion height of 0.0.
It is necessary to satisfy the following expression in the range of 5 to 0.3 μm.

[0022]

[Formula 4] logY ≧ −5X (where X represents the projection height (μm) on the surface of the release layer, and Y represents the number of protrusions (number / mm ² ) on the surface of the release layer).

The release film of the present invention further comprises a log Y
It is preferable to satisfy ≧ −6X. logY <-5X
In this case, even if Ra satisfies 30 nm or less, extremely rare surface protrusions cause problems such as repelling the slurry at the time of slurry application or breaking at the time of peeling the green sheet. By satisfying the above expression, a release surface free of high surface protrusions can be obtained. Further, in the release film of the present invention, the number of protrusions having a protrusion height of 0.4 μm or more on the surface of the release layer is 35 / m.
m ² or less, more preferably 3
0 / mm ² or less. The number of projections is 35 / mm ²
In the case of exceeding, the extremely large coarse projections cause problems such as repelling the slurry at the time of applying the ceramic slurry.

In the release film of the present invention, the center line average roughness (hereinafter referred to as Ra) of the surface on which the release layer is not provided is provided.
(Abbreviated as (B)) preferably satisfies the following formula in terms of preventing blocking of the release film or improving the transportability of the release film.

[0025]

## EQU5 ## 15 ≦ Ra (B) ≦ 40 (nm) ............

When the Ra (B) is less than 15 nm, problems such as blocking may occur when the release film is wound up in a roll shape, while when it exceeds 40 nm, the release layer of the release film may not be formed. In some cases, defects such as scratches on the surface of the release layer or the surface of the green sheet due to the surface not provided, and transfer of roughness may occur.

[0027]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples. In the Examples and Comparative Examples, “parts” indicates “parts by weight” as solid content. The evaluation method used in the present invention is as follows.

(1) Measurement of average particle size (d ₅₀ : μm) Integration in equivalent spherical distribution (weight basis) measured using a centrifugal sedimentation type particle size distribution analyzer (SA-CP3 manufactured by Shimadzu Corporation) ) The value of 50% was taken as the average particle size. (2) Evaluation of surface roughness (Ra) Using a surface roughness measuring instrument (SE-3F) manufactured by Kosaka Laboratory Co., Ltd.
It measured according to JIS-B-0601-1982. However, the cutoff value was 80 μm and the measurement length was 2.5 mm.

(3) Measurement of the distribution curve of the release layer surface of the release film and the number of protrusions having a protrusion height of 0.4 μm or more Three-dimensional surface roughness tester (SE-3AK) manufactured by Kosaka Laboratory Co., Ltd.
Under the conditions of a tip radius of a stylus of 5 μm, a stylus pressure of 30 mg, a measurement length of 0.5 mm, a sampling pitch of 1.0 μm, a cutoff of 0.25 mm, a vertical magnification of 50,000 times, a horizontal magnification of 200 times, and 500 operations. The protrusion height and the number of protrusions were measured.
In the present invention, the projection height (X, (μm)) is defined as the height of the surface where the number of projections is the maximum, and the height from this level is defined as the projection height, and the relationship between the number of projections at each projection height. Was graphically represented as a distribution curve. The number of protrusions having a protrusion height of 0.4 μm or more is determined by the above method.
The total number of protrusions corresponding to the protrusions exceeding 4 μm was expressed.

(4) Evaluation of Coatability of Ceramic Slurry A ceramic slurry having the following composition was wetted for 5 μm.
m was applied on the release surface of the sample sample, and the slurry coatability at that time was determined according to the following 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) 10 Part << Judgment Criteria >> ：: Slurry coatability is good.

(5) Evaluation of peelability of green sheet The green slurry was formed into a sheet having a thickness of 3 μm (after drying) using the ceramic slurry used in (4), and then a release film and a green sheet were formed. Was determined according to the following criteria. << Judgment Criteria >> ：: Smooth peeling possible △: Slight peeling feeling ×: Hard to peel or peeling too light △ or more is a level that does not pose any practical problem.

(6) Evaluation of Blocking Property of Release Film After cutting a sample sample into 10 cm squares, 10 samples were stacked so that the release surface and the surface on which the release layer was not provided were aligned.
After pressing at 100 ° C. for 1 hour under a condition of 10 kg / cm ² , the occurrence of blocking was confirmed. << Judgment Criteria >> ：: No blocking has occurred x: Blocking has occurred ○ is a practically acceptable level.

<Production of Raw Material Polyester> Production Example 1 (Polyester A) 100 parts of dimethyl terephthalate, 60 parts of ethylene glycol and 0.09 part of magnesium acetate tetrahydrate were placed in a reactor, heated and heated, and methanol was distilled off. And
The transesterification reaction was performed, and the temperature was raised to 230 ° C. over 4 hours from the start of the reaction, and the transesterification reaction was substantially completed. Subsequently, 0.5 part of calcium carbonate particles having an average particle diameter of 0.6 μm, 0.04 part of phosphoric acid, and 0.04 part of antimony trioxide
After adding 100 parts, the temperature was raised to 280 ° C. and the pressure was raised to 1 in 100 minutes.
The pressure reached 5 mmHg, and thereafter the pressure was gradually reduced to finally 0.05 mmHg. After 4 hours, the inside of the system was returned to normal pressure to obtain polyester A. Polyester A had a calcium carbonate particle content of 0.5% by weight.

Production Example 2 (Polyester B) Instead of adding 0.5 parts of calcium carbonate particles having an average particle diameter of 0.6 μm to the polyester A obtained in Production Example 1, titanium oxide having an average particle diameter of 0.7 μm was used. Polyester B was obtained in the same manner as above except that 0.3 parts of particles were added. The content of the titanium oxide particles having an average particle size of 0.7 μm in the polyester B was 0.3% by weight.

Production Example 3 (Polyester C) In the polyester A obtained in Production Example 1, instead of adding 0.5 parts of calcium carbonate particles having an average particle diameter of 0.6 μm, spherical silica having an average particle diameter of 2.4 μm was used. Produced in the same manner as in Production Example 1 except that 0.1 parts of particles were added,
Polyester C was obtained. 1. average particle size of polyester C
The content of the 4 μm spherical silica particles was 0.1% by weight.

<Production of Polyester Film> Production Example 5 (Polyester Film F1) Polyester A produced in Production Example 1 was dried at 180 ° C. for 4 hours in an inert gas atmosphere, and then dried at 290 ° C. by a melt extruder.
C., extruded from a die, cooled and solidified on a cooling roll having a surface temperature set to 40.degree. C. using an electrostatic contact method to obtain an unstretched sheet. 2. The obtained sheet was heated at 85 ° C.
After stretching 4 times in the longitudinal direction, an antistatic layer having the following composition was applied, guided to a tenter, stretched 3.6 times in the transverse direction at 100 ° C, and heat-fixed at 230 ° C. (After drying), a polyester film F1 having a thickness of 38 μm, on which an antistatic layer of 0.1 g / m ² was provided.

The composition of the antistatic layer was 40% by weight of an antistatic agent ("ST-1000" manufactured by Mitsubishi Chemical Corporation) and 60% by weight of methoxymethylmelamine. Production Example 6 (Polyester film F2) Except for using Polyester B instead of Polyester A in Production Example 5, a thickness of 3
An 8 μm polyester film F2 was obtained.

Production Example 7 (Polyester film F3) A thickness of 3 was obtained in the same manner as in Production Example 5 except that Polyester C was used instead of Polyester A.
An 8 μm polyester film F3 was obtained. Production Example 8 (Polyester film F2) In Production Example 7, a thickness of 3 was obtained in the same manner as in Production Example 7 except that polyester B was used instead of polyester A.
An 8 μm polyester film F2 was obtained.

Production Example 9 (Polyester film F3) A thickness of 3 was obtained in the same manner as in Production Example 7 except that Polyester C was used instead of Polyester A.
An 8 μm polyester film F3 was obtained. Production Example 10 (Polyester film F4) A film having a thickness of 3 was produced in the same manner as in Production Example 7 except that Polyester D was used instead of Polyester A.
An 8 μm polyester film F4 was obtained.

Production Example 11 (Polyester film F5) A film having a thickness of 3 was produced in the same manner as in Production Example 7 except that Polyester E was used instead of Polyester A.
An 8 μm polyester film F5 was obtained. Production Example 12 (Polyester film F6) Thickness of 3 was obtained in the same manner as in Production Example 7 except that Polyester F was used instead of Polyester A.
An 8 μm polyester film F6 was obtained.

Example 1 An antistatic layer was applied to the polyester film F1 obtained in Production Example 5 so that the coating amount (after drying) of a release agent having the following composition was 0.1 g / m ^2. A release layer was applied to the surface to obtain a release film. The properties of the obtained film are shown in Table 1 below. The composition of the release agent was 100 parts of a curable silicone resin ("KS-779H" manufactured by Shin-Etsu Chemical Co., Ltd.), 1 part of a curing agent ("CAT-PL-8" manufactured by Shin-Etsu Chemical Co., Ltd.), and silica particles (average particle size: 0.1%). 02 μm) and 2,200 parts of a methyl ethyl ketone (MEK) / toluene mixed solvent system.

Example 2 Polyester film F2 (38) obtained from Production Example 6
μm) and a release film was obtained in the same manner as in Example 1 except that a release layer was coated on the surface provided with the antistatic layer. Table 1 shows the properties of the obtained film. Comparative Example 1 The polyester film F3 (3
8 μm), the same release layer as in Example 1 was applied on the surface opposite to the surface on which the antistatic layer was applied, to obtain a release film. Table 1 shows the properties of the obtained film.

Comparative Example 2 The polyester film F3 (3
8 μm), and a release film was obtained in the same manner as in Example 1 except that a release layer was coated on the surface on which the antistatic layer was coated. Table 1 shows the obtained film properties. Comparative Example 3 Polyester film F4 obtained in Production Example 10
(38 μm), and a release film was obtained in the same manner as in Example 1 except that a release layer was applied on the surface on which the antistatic layer was applied. The properties of the obtained film are shown in Table 2 below.

Comparative Example 4 Polyester film F5 obtained in Production Example 11
(38 μm), and a release film was obtained in the same manner as in Example 1 except that a release layer was applied on the surface on which the antistatic layer was applied. Table 2 shows the obtained film properties. Comparative Example 5 Polyester film F6 obtained in Production Example 12
(38 μm), and a release film was obtained in the same manner as in Example 1 except that a release layer was applied on the surface on which the antistatic layer was applied. Table 2 shows the obtained film properties.

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

When the release film of the present invention is used for a ceramic laminated capacitor, especially for forming a thin film green sheet of 5 μm or less, even if the release film is wound into a roll, no blocking or the like occurs. Its industrial value is high.

Claims (3)

[Claims] 1. A release film comprising a polyester film having a release layer coated on one surface, wherein the surface of the release layer has a center line average roughness (Ra) of 30 nm or less, and A distribution curve representing the relationship between the projection height (X) and the number of projections (Y) satisfies the following expression when the projection height is in the range of 0.05 to 0.3 μm, and the projection height on the surface of the release layer is 0. A release film for forming a thin film green sheet, wherein the number of protrusions of 4 μm or more is 35 / mm ² or less. [Formula 1] logY ≧ −5X (where X represents the height of protrusions (μm) on the surface of the release layer, and Y represents the number of protrusions (number / mm ² ) on the surface of the release layer). 2. The release film according to claim 1, wherein the following formula is satisfied. ## EQU2 ## 15 ≦ Ra (B) ≦ 40 (nm) (where Ra (B) represents the center line average roughness of the surface on which the release layer is not provided) 3. The release film according to claim 1, wherein the release layer contains a curable silicone resin.