JPH11320764A - Release film for molding membrane green sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a release film, wherein a release layer has a flat surface, not generating blocking or the like even if taken up in a roll form and capable of corresponding to the molding of a membrane green sheet. SOLUTION: A release film wherein a release layer is applied to the single surface of a polyester film obtained by laminating at least two layers by co- extrusion is characterized by that the center line average roughness (Ra) of the surface of the release layer is 30 nm or less and a distribution curve showing the relation between the height (X) of projections on the surface of the release layer and the number (Y) of projections satisfies the formula: log Y>=-5X [wherein X is the height (μm) of the projections on the surface of the release layer; and Y is the number per mm<2> of projections on the surface of the release layer] in a projection height range of 0.05-0.3 μm and the number of projections with a height of 0.4 μm or more on the surface of the release layer is 35/mm<2> or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a release film, and more particularly to a 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 applied on one surface of a polyester film in which at least two layers are laminated by co-extrusion, and the center line average roughness of the release layer surface ( Ra) is 30 nm or less, and the projection height (X) and the number of projections (Y) on the surface of the release layer
Distribution curve showing the relationship with the projection height 0.05-0.3μ
m, wherein the following formula is satisfied and the number of projections having a projection height of 0.4 μm or more on the surface of the release layer is 35 / mm ² or less.

[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. The laminated polyester film constituting the release film according to the present invention is obtained by stretching and heat-treating a resin extruded by a so-called co-extrusion method in which the resin constituting each layer is co-melt extruded from an extruder. . Hereinafter, a co-extruded two-layer or three-layer film will be described as a laminated polyester film, but is not limited thereto, and may be a multilayer of four or more layers as long as the gist of the present invention is not exceeded.

In the laminated polyester film of the present invention, the surface on which the release layer is provided is the A surface, the layer constituting the surface is the A layer, the opposite surface is the B surface, and the layer constituting the B surface is the B layer.
The layer and the layers other than these will be described below as a C layer. In this case, the laminated structure in the thickness direction is A / B or A / C / B
And the like. In the present invention, the polyester used for the laminated polyester film may be a homopolyester or a copolyester. As the homopolyester, those obtained by polycondensing an aromatic dicarboxylic acid and an aliphatic glycol may be used.
As the aromatic dicarboxylic acid, terephthalic acid, 2,6-
Examples include naphthalenedicarboxylic acid, and examples of the aliphatic glycol include ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol. Typical polyesters include polyethylene terephthalate (PET) and polyethylene-2,6-naphthalenedicarboxylate (PEN).
On the other hand, as the copolymerized polyester, a copolymer containing a third component of usually 30 mol% or less can be used. As the dicarboxylic acid component of the copolymerized polyester,
Isophthalic acid, terephthalic acid phthalate, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, and
Oxycarboxylic acid (for example, P-oxybenzoic acid, etc.)
And the glycol component includes one or more of ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, and the like.

In the present invention, the ratio of the thickness of the layer A / (the thickness of the layer B or the layer B + C) is preferably 0.1 or more, more preferably 0.2 or more. When the thickness composition ratio is less than 0.1, the surface roughness of the A layer may be increased due to the influence of the particles contained in the B layer or the C layer. Further, the thickness of the layer B is preferably 1 μm or more, and if it is less than 1 μm, a problem such as the particles falling off the layer B may occur.

In the release film of the present invention, it is necessary to keep the surface roughness of the release layer surface of the release film within a specific range. From this viewpoint, the center line average roughness of the side A of the laminated polyester film constituting the release film of the present invention is not particularly limited, but is preferably in the range of 5 to 50 nm.

On the other hand, the center line average roughness of the surface of the laminated polyester film B is not particularly limited, either.
When the thickness is in the range of 40 nm, workability at the time of handling the film is improved, which is preferable. In the present invention, it is preferable to mix particles such as silica, calcium carbonate, kaolin, titanium oxide, and aluminum oxide in the laminated polyester film. In this case, the average particle size and the amount of the particles used are not particularly limited, but particularly the average particle size and the amount of the particles contained in the polyester layer in contact with the release layer, the average particle size Is 0.1 ~
1.0 μm is preferable, and the amount of addition is 0.1 to 1
% By weight, and more preferably in the range of 0.3 to 1% by weight.

The method for blending the particles into the polyester is not particularly limited, and any conventionally known method can be employed. For example, it can be added at any stage of producing the polyester, but is preferably added as a slurry dispersed in ethylene glycol or the like at the esterification stage or at the stage before 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

The laminated polyester film of the present invention may have any thickness as long as it can be formed as a film, and usually has a total film thickness of 9 to 350 μm, more preferably 12 to 250 μm.
m. Next, a method for producing a laminated polyester film constituting the release film of the present invention will be specifically described, but the laminated polyester film of the present invention is not limited to the following production examples.

That is, the above-mentioned polyester raw materials are laminated using two or more extruders, two or three or more multi-manifolds or feed blocks, and extruded as a molten sheet from a slit die. . Next, a method in which the molten sheet extruded from the die is cooled and solidified by a cooling roll to obtain an unstretched sheet is preferable. 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. In the present invention, both may be used as needed.

Next, the obtained unstretched film is stretched biaxially and biaxially oriented. That is, first, the unstretched sheet is stretched in one direction by a roll or tenter type stretching machine. The stretching temperature is usually 70 to 120 ° C,
Preferably it is 80-110 degreeC, and a draw ratio is 2.5-7 times normally, Preferably it is 3.0-6 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 above stretching step can be performed. It is not limited to, for example,
After the first-stage stretching is completed, before the second-stage stretching, an aqueous solution, an aqueous emulsion, an aqueous slurry, or the like is used for the purpose of improving antistatic properties, sliding properties, adhesiveness, and the like, and improving secondary workability. The coating process can be performed.

In the above-mentioned stretching, the unidirectional stretching is performed by 2
It is also possible to use a method of performing the above steps. In that case,
It is preferable that the stretching is performed so that the stretching ratio in the two directions finally falls within the above range. It is also possible to simultaneously biaxially stretch the unstretched sheet so that the area magnification becomes 10 to 40 times. Further, if necessary, the film may be stretched in the longitudinal and / or transverse directions again before or after the heat treatment.

Further, various kinds of stabilizers, ultraviolet absorbers, lubricants, pigments, antioxidants and plasticizers may be added to the laminated 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. A modified silicone type by graft polymerization with an organic resin such as a resin may be used. Among them, those containing a curable silicone resin as a main component are good in terms of 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 curing type, a solventless electron beam curing type, and the like. 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 DKQ3-20
2, DKQ3-203, DKQ3-204, DKQ3-
205, DKQ3-210, YSR manufactured by Toshiba Silicone Co., Ltd.
-3022, TPR-6700, TPR-6720, T
PR-6721, etc., manufactured by Toray Dow Corning Silicone Co., Ltd. SD7223, SD7226, SD7229, SR
X-210 and the like.

In the present invention, a conventionally known coating method such as reverse roll coating, gravure coating, bar coating, etc. can be used as a method for applying a release layer on the A side of the laminated polyester film. The coating amount of the release layer is from 0.01 to
5 g / m ² is preferred. When the coating amount is less than 0.01 g / m ² , the coating properties tend to lack stability.
If the thickness exceeds g / m ² , a problem may occur in terms of curability.

Further, in the present invention, particles may be added to the release layer for the purpose of preventing blocking on the surface of the release layer and improving the slipperiness. The type of particles to be used may be either organic particles or inorganic particles, and is not particularly limited. 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 side A of the laminated polyester film and the release layer, or on the side where the release layer is not provided. The laminated polyester film may be subjected to a surface treatment such as a corona treatment and a plasma treatment.

In the coating layer, 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, if necessary. Etc. 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 (Ra) of the surface of the release layer of the release film of the present invention must satisfy 30 nm or less, and by setting it to 20 nm or 15 nm or less, a thin film having a thickness of 5 μm or less can be obtained. It is possible to sufficiently cope with green sheet molding. Ra of the release layer surface is 30
If it exceeds nm, problems such as repelling of the slurry during the application of the ceramic slurry will occur.

The lower limit of Ra on the surface of the release layer is set at 5n in consideration of workability when handling the release film.
It is preferred that m be the lower limit. In the present invention, as a method for adjusting the Ra of the release layer surface of the release film to a range of 30 nm or less, for example, a coating layer is provided in advance on a polyester film, and after the film surface is flattened, the release layer is formed. A method of coating is used.

In the release film of the present invention, the distribution curve showing the relationship between the projection height (X) and the number of projections (Y) on the release layer surface is as follows when the projection height is in the range of 0.05 to 0.3 μm. It is necessary to satisfy the formula.

[0027]

[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 (Ra) of the surface on which the release layer is not provided is provided.
It is preferable that (B)) satisfies the following expression in terms of preventing blocking of the release film or improving the transportability of the release film.

[0030]

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

If the Ra (B) is less than 15 nm, problems such as blocking may occur when the release film is wound into a roll. On the other hand, if Ra (B) is more than 40 nm, the release layer of the release film may be damaged. 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.

[0032]

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 Green Sheet Peelability After the green slurry was formed into a sheet having a thickness of 3 μm (after drying) using the ceramic slurry used in (4), 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 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 to carry out a transesterification reaction. The temperature was raised to 230 ° C. over 4 hours from the start of the reaction, and the transesterification was substantially completed. Then, silica particles having an average particle size of 0.1 μm were added.
After adding 1 part, phosphoric acid 0.04 part and antimony trioxide 0.04 part, the temperature was 280 ° C. and the pressure was 15 mm in 100 minutes.
Hg, and then gradually reduce the pressure to reach 0.0
It was 5 mmHg. After 4 hours, the inside of the system was returned to normal pressure to obtain polyester A. Polyester A had a silica particle content of 0.1% by weight.

Production Example 2 (Polyester A1) to Production Example 9
(Polyester B2) Various polyesters were obtained in the same manner as in Production Example 1, except that the combination of the type of particles used, the average particle diameter, and the amount of particles added in the polyester were different. The constitution of each polyester is as shown in Table 1 below.

<Production of Laminated Polyester Film> Production Example 10 (Laminated Polyester Film F1) Polyester A and polyester B1 were separately separated by 18
Dried at 0 ° C. for 4 hours in an inert gas atmosphere, melted at 290 ° C. by a separate melt extruder, extruded from a die, and placed on a cooling roll set to a surface temperature of 40 ° C. using an electrostatic contact method. After cooling and solidification, a laminated unstretched sheet was obtained. The obtained sheet was stretched in the longitudinal direction by 3.4 times at 85 ° C. Next, the film was guided to a tenter and stretched 3.6 times in the transverse direction at 100 ° C., and then heat-set at 230 ° C. to a thickness of 38 μm.
To obtain a laminated polyester film F1. Layer structure is A /
B1 and the thickness of each layer was 10/28 (μm).

Production Example 11 (Laminated polyester film F
2) A laminated polyester film F2 having a thickness of 38 μm was obtained in the same manner as in Production Example 10, except that Polyester A1 was used instead of Polyester A. The layer configuration is A1 / B1, and the thickness of each layer is 10/28 (μ
m). Production Example 12 (Laminated Polyester Film F3) The laminated polyester film F2 obtained in Production Example 11 was further coated with 0.2 g of a coating amount on the polyester A1 surface.
/ Antistatic layers m ² to obtain a laminated polyester film F3 thick 38μm laminated. The composition of the antistatic layer is 40% by weight of an antistatic agent (“ST-1000” manufactured by Mitsubishi Chemical Corporation) and 60% by weight of methoxymethylmelamine. The layer configuration is A1 / B1, and the thickness of each layer is 10/28 (μm).
Met.

Production Example 13 (Laminated polyester film F
4) In Production Example 10, a laminated polyester film F4 having a thickness of 38 μm was obtained in the same manner as in Production Example 10, except that polyester A2 was used instead of polyester A. The layer configuration is A2 / B1, and the thickness of each layer is 10/28 (μ
m). Production Example 14 (Polyester Film F5) A 38 μm-thick polyester film F5 was obtained in the same manner as in Production Example 10 except that Polyester B1 was used instead of Polyester A.

Production Example 15 (Laminated polyester film F
6) In Production Example 10, a laminated polyester film F6 having a thickness of 38 µm was obtained in the same manner as in Production Example 10, except that polyester A3 was used instead of polyester A. The layer configuration is A3 / B1, and the thickness of each layer is 10/28 (μ
m). Production Example 16 (laminated polyester film F7) In Production Example 10, except that polyester B2 was used instead of polyester B1,
A 38 μm-thick laminated polyester film F7 was obtained.
The layer configuration is A / B2, and the thickness of each layer is 10/28 (μ
m).

Production Example 17 (Polyester Film F8) In Production Example 10, a single-layered polyester film F8 having a thickness of 38 μm was obtained using only polyester A without using polyester B1. Production Example 18 (Laminated Polyester Film F9) A laminated polyester film F9 having a thickness of 38 μm was obtained in the same manner as in Production Example 10, except that polyester A4 was used instead of polyester A. The layer configuration is A4 / B1, and the thickness of each layer is 10/28 (μ
m).

Production Example 19 (Laminated polyester film F
10) In Production Example 10, a laminated polyester film F10 having a thickness of 38 µm was obtained in the same manner as in Production Example 10 except that polyester A5 was used instead of polyester A.
The layer configuration is A5 / B1, and the thickness of each layer is 10/28.
(Μm). Production Example 20 (Laminated Polyester Film F11) A 38 μm-thick laminated polyester film F11 was obtained in the same manner as in Production Example 10, except that polyester A6 was used instead of polyester A.
The layer configuration is A6 / B1, and the thickness of each layer is 10/28.
(Μm).

Example 1 Laminated polyester film F1 obtained from Production Example 10
A release agent having the following composition was applied to the A side of the above so that the coating amount was 0.1 g / m ² to obtain a release film. The composition of the release agent is a curable silicone resin ("KS-779" manufactured by Shin-Etsu Chemical Co., Ltd.).
H ") 100 parts, curing agent (" CAT-PL "manufactured by Shin-Etsu Chemical Co., Ltd.
-8 ") 1 part, and 2200 parts of a methyl ethyl ketone (MEK) / toluene mixed solvent system. The properties of this film are shown in Table 3 below.

Example 2 Laminated polyester film F2 obtained from Production Example 11
(38 μm), except that a release film was obtained in the same manner as in Example 1. Table 3 shows the properties of this film. Example 3 Laminated polyester film F obtained in Production Example 12
A release layer similar to that of Example 1 was applied on the surface on which the antistatic layer 3 (38 μm) was applied to obtain a release film. Table 3 shows the properties of this film.

Example 4 Laminated polyester film F4 obtained from Production Example 13
(38 μm), except that a release film was obtained in the same manner as in Example 1. Table 3 shows the properties of this film. Example 5 Laminated polyester film F obtained in Production Example 16
7 was manufactured in the same manner as in Example 1 except that 38 μm was used to obtain a release film. Table 3 shows the film characteristics.

Comparative Example 1 The polyester film F5 (3
8 μm) to produce a release film in the same manner as in Example 1. Table 3 shows the properties of this film. Comparative Example 2 Laminated polyester film F obtained in Production Example 15
6 (38 μm), except that a release film was obtained in the same manner as in Example 1. Table 3 shows the film characteristics.

Comparative Example 3 Polyester film F8 obtained in Production Example 17
(38 μm), except that a release film was obtained in the same manner as in Example 1. Table 3 shows the film characteristics. Comparative Example 4 Laminated polyester film F obtained in Production Example 18
Except that 9 (38 μm) was used, it was manufactured in the same manner as in Example 1 to obtain a release film. Table 3 shows the film characteristics.

Comparative Example 5 Laminated polyester film F obtained in Production Example 19
Except for using 10 (38 μm), it was manufactured in the same manner as in Example 1 to obtain a release film. Table 3 shows the film properties.
Shown in Comparative Example 6 Laminated Polyester Film F Obtained by Production Example 20
A release film was obtained in the same manner as in Example 1 except that 11 (38 μm) was used. Table 3 shows the film properties.
Shown in

[0053]

[Table 1]

[0054]

[Table 2]

[0055]

[Table 3]

[0056]

When the release film of the present invention is used for a multilayer ceramic capacitor, particularly for forming a thin film green sheet having a thickness of 5 μm or less, even if the release film is wound into a roll, blocking or the like occurs. No, its industrial value is high.

Claims (3)

[Claims] At least two layers are laminated by coextrusion.
The release layer is not applied on one side of the polyester film
Release film, the center line average roughness of the release layer surface
(Ra) is 30 nm or less, and the protrusion height on the surface of the release layer
The distribution curve representing the relationship between (X) and the number of projections (Y) is the height of the projections.
In the range of 0.05 to 0.3 μm,
35 protrusions with a protrusion height of 0.4 μm or more on the surface of the release layer
Pieces / mm ^Two A thin film green chip characterized by the following:
Release film for sheet molding. [Formula 1] logY ≧ −5X (where X is the projection height (μm) of the release layer surface, and Y is
Number of protrusions on the release layer surface (pcs / mm^Two ) 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.