JP2001323079A - Release polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a release polyester film causing no defects derived from film surface asperities such as pinholes on a green sheet involving the film and capable of preventing occurrence of defects on such a green sheet due to flaows or shaving which may occur in the green sheet's production or processing line. SOLUTION: This release polyester film is such that at least one side of a polyester base film is provided with a release layer, being characterized by that there are >=100 asperities/mm2 each >=0.27 μm but <0.54 μm in height on the surface of the release layer, and <=5.0 asperities/mm2 each >=0.54 μm in height, there are substantially no asperities each >=0.81 μm in height, and a three-dimensional average surface roughness SRa is 0.010-0.030 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a release polyester film having a polyester film as a base material, and more particularly to a release polyester film used for forming a green sheet for a ceramic capacitor.

[0002]

2. Description of the Related Art Release films obtained by laminating a release layer on a polyester base film are widely used as adhesive labels, adhesive tape mounts and the like. In recent years, the use of a release film for forming a green sheet for a ceramic capacitor has been generalized, and the thinning of the green sheet has been promoted with the increase in capacity and miniaturization of the capacitor.

[0003] With the thinning of the green sheet, when a release film having a large surface roughness is used, problems such as the occurrence of defects such as pinholes in the green sheet and the occurrence of breakage upon peeling occur. The frequency has been increasing.

In order to solve these problems, techniques for controlling the roughness of the release layer surface of a release film are disclosed in, for example, JP-A-11-320524 and JP-A-11-32076.
The release surface described in Japanese Unexamined Patent Application Publication No. 4 (1999) -2004 has a center line average roughness R
When a is not more than 30 nm and the height of the protrusions is in the range of 0.05 to 0.3 μm, the logarithmic value of the number of protrusions (the number of Log protrusions) is at least minus 5 times (−5 × the height of the protrusions) the height of the protrusions. It is disclosed that the number of protrusions of 0.4 μm or more is 35 / mm ² or less.

However, these methods can eliminate defects such as pinholes in the green sheet due to surface protrusions of the release film, but they do not affect the film at the time of film production process or processing such as formation of a release layer. It was found that problems such as scratching and film surface scraping were likely to occur. Scratches and scraping of these films are not preferred because they cause defects in the green sheet.

The inventors of the present invention have conducted intensive studies on the causes of the scratches and abrasion of these films.
It has been found that the main factor is that the number of protrusions of not less than 0.5 μm and not more than 0.54 μm is small. Therefore, at the time of processing such as a film manufacturing process or forming a release layer, a metal roll or the like comes into contact with a background portion having no protrusions on the release layer surface or a protrusion having a low protrusion height of less than 0.27 μm. When you do
It is presumed that the true contact area increased, and that the surface of the release layer was damaged or scraped.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a green sheet which is free from defects such as pinholes originating from film surface projections, and which is caused by scratches and scrapes generated in the manufacturing and processing steps. An object of the present invention is to provide a release polyester film capable of suppressing the occurrence of the above-mentioned drawbacks.

[0008]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above situation, and the release polyester film capable of solving the above problems is as follows.

That is, a first invention of the present invention is a polyester film for release, in which a release layer is provided on at least one surface of a polyester base film, wherein the projection height of the release layer surface is 0.1 mm. The number of protrusions having a size of 27 μm or more and less than 0.54 μm is 100 or more / mm ² , the height of the protrusions is 0.55 μm or more, 5.0 / mm ² or less, and the height of the protrusions is substantially 0.81 μm or more. Without, and three-dimensional average surface roughness S
A release polyester film, wherein Ra is from 0.010 to 0.030 μm.

In a second aspect, the polyester base film has a heat shrinkage in the longitudinal direction at 150 ° C. of 2.0.
%, And a heat shrinkage in the longitudinal direction at 200 ° C. of 3.0% or more is the release polyester film according to the first invention.

A third invention is characterized in that the polyester base film is made of polyethylene terephthalate or polyester mainly composed of polyethylene terephthalate.
Or the release polyester film according to the second aspect of the invention.

[0012] A fourth invention is the release polyester film according to the first invention, wherein the polyester base film mainly comprises polylactic acid.

A fifth invention is the release polyester film according to the fourth invention, wherein the polyester base film has a heat shrinkage at 120 ° C. of 5.0% or less.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester used as the base film of the present invention may be a homopolyester or a copolyester. Isophthalic acid, phthalic acid, diphenyl-4,4-
Dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, naphthalene-1,5
Dicarboxylic acid, diphenoxyethane-4,4-dicarboxylic acid, diphenylsulfone-4,4-dicarboxylic acid,
Acid components such as diphenyl ether-4,4-dicarboxylic acid, malonic acid, 1,1-dimethylmalonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, decamethylene dicarboxylic acid, and ethylene glycol, propylene glycol, and tetramethylene glycol , Neopentyl glycol, cyclohexane dimethanol, hydroquinone,
A glycol component such as bisphenol A, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, or a copolymer thereof may be copolymerized. In addition, aliphatic polyesters such as polylactic acid, polyglycolic acid, and poly (2-oxybutyric acid) can also be used.

The release polyester film of the present invention may contain inorganic particles and / or organic salt particles in a base film and / or a release layer in order to improve handling properties such as slipping property, winding property and blocking resistance. And inert particles such as crosslinked polymer particles.

Examples of the inorganic particles include calcium carbonate, kaolin, talc, magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, lithium phosphate, calcium phosphate, magnesium phosphate, aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, and fluorine oxide. Lithium oxide, sodium calcium aluminum silicate and the like.

Examples of the organic salt particles include calcium oxalate, terephthalate such as calcium, barium, zinc, manganese and magnesium.

Examples of the crosslinked polymer particles include homopolymers or copolymers of vinyl monomers such as divinylbenzene, styrene, acrylic acid, methacrylic acid, acrylic acid or methacrylic acid. In addition, polytetrafluoroethylene, benzoguanamine resin, thermosetting epoxy resin,
Organic particles such as an unsaturated polyester resin, a thermosetting urea resin, and a thermosetting phenol resin may be used.

The method for incorporating the inert particles into the polyester serving as the base film is not particularly limited.
(A) a method in which inert particles are dispersed in a slurry state in a diol which is a polyester constituent, and the inert particle slurry is added to a polyester polymerization reaction system; Examples thereof include a method of adding a water slurry of inert particles dispersed in a molten polyester resin using a twin-screw extruder, and a method (c) of kneading the polyester resin and the inert particles in a molten state.

In the case of adding to a polymerization reaction system, it is preferable to add a diol slurry of inert particles to a reaction system having a low melt viscosity from before the esterification reaction or transesterification reaction to before the start of the polycondensation reaction. When preparing the diol slurry of the inert particles, it is preferable to perform a physical dispersion treatment such as a high-pressure disperser, a bead mill, or ultrasonic dispersion. Further, in order to stabilize the slurry subjected to the dispersion treatment, it is preferable to use an appropriate chemical dispersion stabilization treatment in accordance with the type of particles used.

As the dispersion stabilizing treatment, for example, in the case of inorganic oxide particles or cross-linked polymer particles having a carboxyl group on the particle surface, an alkali compound such as sodium hydroxide, potassium hydroxide, lithium hydroxide or the like is slurried. And re-aggregation between particles can be suppressed by electric repulsion. In the case of calcium carbonate particles or hydroxyapatite particles, it is preferable to add sodium tripolyphosphate or potassium tripolyphosphate to the slurry.

When the diol slurry of the inert particles is added to the polyester polymerization reaction system, the slurry may be heated to near the boiling point of the diol, or the heat shock (slurry and polymerization reaction) when the slurry is added to the polymerization reaction system. (Temperature difference from the system) can be reduced, which is preferable in terms of particle dispersibility.

The relationship between the height and the number of protrusions and the three-dimensional average surface roughness SRa according to claim 1 of the present invention can be controlled by the film forming conditions and the inert particles. The type and content of the inert particles are not particularly limited as long as the relationship between the height and the number of the protrusions and the three-dimensional average surface roughness SRa satisfy the range described in claim 1.

The average particle size of the inert particles is preferably from 0.1 μm to 2.5 μm, and more preferably from 0.2 μm to 1.0 μm.
The following are particularly preferred. The average particle size of the inert particles is 0.1
If less than μm, the protrusion height is 0.27 μm or more and 0.54 μm.
It is difficult to make the number of projections less than 100 / mm ² or more and the three-dimensional average surface roughness SRa to 0.010 μm or more, and if the average particle diameter is more than 2.5 μm, the projections having a projection height of 0.54 μm or more will not be formed. It is difficult to prevent substantially no protrusions of 5.0 protrusions / mm ² or less and a protrusion height of 0.81 μm or more.

When inert particles are contained in the polyester base film, the content of the inert particles is preferably 0.02% by weight or more and 0.8% by weight or less with respect to the polyester, particularly preferably 0% by weight or less. 0.1% by weight or more and 0.5% by weight or less. 0.02% by weight of inert particles
If the height is less than 0.27 μm or more and less than 0.54 μm, it is difficult to set the number of protrusions to 100 / mm ² or more and the three-dimensional average surface roughness SRa to 0.010 μm or more,
If it exceeds 0.8% by weight, it is difficult to reduce the three-dimensional average surface roughness SRa to 0.030 μm or less.

As the inert particles contained in the polyester base film used in the present invention, two or more kinds of particles having different average particle diameters can be used in combination. When two or more kinds of inert particles having different average particle diameters are contained in the film, use inert particles having a smaller Mohs hardness than inert particles having a smaller average particle diameter as the inert particles having a larger average particle diameter. Is preferred from the viewpoint of scratch resistance and wear resistance.

As the inert particles having a small average particle size, inorganic oxide particles are preferable.
Γ, δ, θ type alumina fine particles, spherical monodisperse silica fine particles, dry-process silica fine particles, and titanium oxide fine particles of up to 0.3 μm are particularly preferred. The content in the film is 0.1.
The content is preferably set to 1 to 0.5% by weight.

As the inert particles having a large average particle diameter,
Calcite-type and vaterite-type synthetic calcium carbonate and the above-mentioned crosslinked polymer particles are preferable, and the average particle diameter is preferably in the range of 0.4 to 1.0 μm. Further, the content in the film is preferably from 0.00.1 to 0.5% by weight.

Further, the inert particles are preferably spherical and have a uniform particle diameter. Specifically, the inert particles have an area of 60% or more with respect to a circumscribed circle, and the degree of dispersion of the particle diameter is 30%. % Is preferable. When the area of the inert particles with respect to the circumscribed circle is less than 60%, the abrasion resistance of the film surface becomes insufficient at the time of production or processing, and the film is easily shaved. In addition, the degree of variation of the particle diameter is 30.
%, It is easy to generate pinholes due to the projections of the film on the green sheet.

The polyester base film that can be used in the present invention can be formed by a known film forming method. As a film forming method, a biaxial stretching method such as a uniaxial stretching method for stretching an unstretched film in a longitudinal direction or a transverse direction, an inflation method, a simultaneous biaxial stretching method, a sequential biaxial stretching method, and then a heat fixing treatment Can be used. For example, as the sequential biaxial stretching method, in addition to a method in which longitudinal stretching and transverse stretching or transverse stretching and longitudinal stretching are sequentially performed, a transverse-longitudinal-longitudinal stretching method, a longitudinal-horizontal-longitudinal stretching method, and a longitudinal-longitudinal-horizontal stretching method are used. A stretching method such as a drawing method can be employed. As the simultaneous biaxial stretching method, a conventional simultaneous biaxial stretching method may be used, but a novel simultaneous biaxial stretching method driven by a linear motor method is preferable. In addition,
It may be biaxially stretched simultaneously in multiple steps. Further, in order to further reduce the heat shrinkage, a vertical relaxation process, a horizontal relaxation process, or the like may be performed as necessary.

The stretching conditions are appropriately adjusted depending on the inert particles contained in the film, and the PCC value of the number of protrusions on the central surface of the roughness and the three-dimensional average surface roughness SRa of the present invention are determined by their combination. There is no particular limitation as long as it falls within the range described in the claims.

In the case of the sequential biaxial stretching method in which the film is stretched in the longitudinal direction by one or more steps and then stretched in the transverse direction, the longitudinal orientation (ΔNx) after the stretching in the longitudinal direction is set to 0.080 or less. Is preferred. When ΔNx exceeds 0.080, formation of surface projections with respect to the content of inert particles tends to be insufficient.

The polyester base film used in the present invention may be a laminated film composed of two or more polyester layers. Since the pinhole inspection of the green sheet is performed by transmitting light in the process of forming the green sheet on the release polyester film of the present invention,
The release polyester film of the present invention requires some transparency. Therefore, if the surface of the release layer provided on the release polyester film of the present invention satisfies the scope of the claims, a polyester containing substantially no inert particles in the core layer of the laminated polyester base film. Can also be used.

In the release polyester film of the present invention, a green sheet for a ceramic capacitor is formed on the surface of the film, and then the green sheet is peeled off. It is necessary to provide. As the release layer, a layer having releasability from the green sheet, for example, a silicone resin, a fluororesin, or the like can be given.

As the silicone resin, a known release agent can be used. For example, it can be used by selecting from those described in “Silicone Material Handbook” (edited by Toray Dow Corning, 1993. 8). Generally, a thermosetting or ionizing radiation-curable silicone resin is used. As the thermosetting silicone resin, any reaction type such as a condensation reaction type and an addition reaction type, and as the ionizing radiation curing type silicone resin, an ultraviolet ray or electron beam curing type can be used.

As the condensation reaction type silicone resin, for example, a polydimethylsiloxane having a terminal -OH group and a polydimethylsiloxane (hydrogensilane) having a terminal -H group are an organic tin catalyst (for example, an organic tin acylate catalyst). ) To form a three-dimensional crosslinked structure.

Examples of the addition-reaction-type silicone resin include those which form a three-dimensional crosslinked structure by reacting polydimethylsiloxane having a vinyl group introduced into a terminal with hydrogen silane using a platinum catalyst.

As the UV-curable silicone resin,
For example, the most basic type uses the same radical reaction as ordinary silicone rubber crosslinking, the one that introduces an acrylic group and photocures it, and the one that decomposes onium salts with ultraviolet rays to generate a strong acid, thereby producing an epoxy ring. And those which are crosslinked by addition reaction of thiol to vinyl siloxane. Electron beams have higher energy than ultraviolet rays, and a radical crosslinking reaction occurs without using an initiator as in the case of ultraviolet curing.

The above-mentioned curable silicone resin preferably has a polymerization degree of about 500,000 to 200,000, particularly about 1,000 to 100,000. Specific examples thereof include KS-718 manufactured by Shin-Etsu Chemical Co., Ltd. , -774, -775, -77
8, -779H, -830, -835, -837, -8
38, -839, -841, -843, -847, -8
47H, X-62-2418, -2422, -212
5, -2492, -2494, -5048, -470,
-2366, -630, X-92-140, -128,
KS-723A-B, -705F, -708A, -88
3, -709, -719, TP manufactured by Toshiba Silicon Corporation
R-6701, -6702, -6703, -3704,
-6705, -6721, -6722, -6700, X
SR-7029, YSR-3022, YR-3286,
DK-Q3-202, -20 manufactured by Dow Corning Co., Ltd.
3, -204, -205, -210, -240, -30
03, -3057, SFXF-2560, SD-7226, -7 manufactured by Dow Corning Toray Silicone Co., Ltd.
229, -7320, BY-24-900, -171,
-312, -374, SRX-375, SYL-OFF
23, SRX-244, SEX-290, IC
SILCOLASE 425 manufactured by I Japan Co., Ltd.
And the like. Also, JP-A-47-3444
No. 7, JP-B-52-40918, etc. can also be used. Further, one of these curable silicone resins may be used alone, or two or more thereof may be used in combination.

As the fluororesin, a known release resin can be used. As such a fluororesin,
For example, a polymer (including an oligomer) comprising a fluorine-containing vinyl polymerizable monomer or a copolymer thereof, or a vinyl containing no fluorine-containing vinyl polymerizable monomer and an alkyl group or functional group substituted with a fluorine atom Copolymers with at least one polymerizable monomer, or a mixture thereof and having 5 to 80 mol% of fluorine atoms are exemplified.

Examples of the polymer comprising the fluorine-containing vinyl polymerizable monomer include poly [2-
(Perfluorononenyloxy) ethyl methacrylate], poly [2- (perfluorononenyloxy) ethyl acrylate], poly [2- (perfluorononenyloxybenzoyloxy) ethyl methacrylate], poly [2- (perfluoro Nonenyloxybenzoyloxy) ethyl acrylate], poly [2,2,2-trifluoroethyl methacrylate], poly [2,2,2-trifluoroethyl acrylate], poly [2,2,3
3,3-pentafluoropropyl methacrylate], poly [2,2,3,3,3-pentafluoropropyl acrylate], poly [1-methyl-2,2,3,3,4
4-hexafluorobutyl methacrylate], poly [1
-Methyl-2,2,3,3,4,4-hexafluorobutyl acrylate], poly [perfluoroheptylethyl methacrylate], poly [perfluoroheptylethyl acrylate], poly [perfluoroheptylvinyl ether], poly [α , Β, β-trifluorostyrene], polyvinylidene fluoride, polyhexafluoropropylene, polytetrafluoroethylene, and the like.

Examples of the vinyl polymerizable monomer which does not contain an alkyl group substituted with a fluorine atom, a functional group, and the like, which can be copolymerized with the fluorine-containing vinyl polymerizable monomer, include a hydrocarbon-based vinyl polymerizable monomer. , Hydrocarbon-based non-conjugated divinyl polymerizable monomer, functional group-containing vinyl polymerizable monomer, and the like. Examples of the hydrocarbon-based vinyl polymerizable monomer include methyl acrylate and propyl acrylate. Butyl acrylate, isoamyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, octadecyl acrylate, lauryl acrylate, cesyl acrylate, N, N-diethylaminoethyl acrylate, methyl methacrylate, propyl methacrylate, methacrylic acid Butyl, isoamyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate Le, octadecyl methacrylate, lauryl methacrylate, Cecil, methacrylic acid N, N-diethylaminoethyl, vinyl acetate,
Vinyl propionate, vinyl caprate, vinyl laurate, vinyl stearate, styrene, α-methylstyrene, p-methylstyrene, vinyl chloride, vinyl bromide,
Vinylidene chloride, allyl heptanoate, allyl acetate, allyl caprate, allyl caproate, vinyl methyl ketone, vinyl ethyl ketone, 1,3-butadiene, 2-chloro-1,3-butadiene, 2,3-dichloro-1, 3
-Butadiene, isoprene, etc., as hydrocarbon-based non-conjugated divinyl polymerizable monomers, for example, ethylene glycol diacrylate, ethylene glycol dimethacrylate, propylene glycol diacrylate, propylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, Polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, divinylbenzene,
Examples of functional group-containing vinyl polymerizable monomers such as vinyl acrylate and dibromoneopentyl glycol dimethacrylate include, for example, acrylic acid, methacrylic acid, acrylamide, methacrylamide, N-methylolacrylamide, N-butoxymethylacrylamide, diacetone acrylamide , Methylol diacetone acrylamide, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, 3-chloro-2-hydroxypropyl methacrylate, and the like. is not.

The thickness of the release layer in the present invention is not particularly limited, but is preferably in the range of 0.05 to 5 μm. If the thickness of the coating film is thinner than this range, the release performance is reduced,
Satisfactory performance cannot be obtained. Conversely, if the thickness of the coating film is greater than this range, it takes a long time for curing, which is not preferable for production.

In the release polyester film of the present invention, a method of providing a release layer on the surface of the polyester base film is not particularly limited, but a coating method is preferably used. For example, coating methods include air doctor coating, knife coating, rod coating, forward rotation roll coating, reverse roll coating, gravure coating, kiss coating, bead coating, slit orifice coating, and cast coating. And the like.

The drying and / or curing (thermal curing, ionizing radiation curing, etc.) of the coating film of the release layer can be performed individually or simultaneously. 80 at the same time
It is preferable to carry out at a temperature of not less than ° C. The drying and curing conditions are preferably at 80 ° C. or higher for 10 seconds or longer. If the drying temperature is less than 80 ° C. or the curing time is less than 10 seconds, the curing of the coating film is incomplete, and the coating film tends to fall off, which is not preferable.

In the release layer, known additives such as an antifoaming agent, a coating improver, a thickener, an antistatic agent, an antioxidant, and an ultraviolet absorber may be used as long as the effects of the present invention are not impaired. Agent,
A curing agent, a dye and the like may be contained.

When a green sheet is formed on the release polyester film of the present invention and the green sheet is peeled off from the release film, static electricity is generated. In particular, when a silicone resin is used for the release layer, the release layer is very easily charged, and the release charge when peeling the green sheet is large. Undesirably, the product yield is reduced, for example, by reattaching to the surface. For this reason, it is preferable to provide an antistatic layer on the release polyester film of the present invention in order to reduce the peeling charge or accelerate the charge decay.

The antistatic layer is formed by applying an antistatic resin composition to a film. This antistatic resin composition needs to contain an antistatic agent, and the antistatic layer has a surface resistivity of 1 × 10 ¹¹ Ω / □.
It is preferable to set the following. Surface specific resistance value is 1 × 10
¹¹ Ω / □ is a level at which ordinary dust does not adhere.

When a release layer is laminated on the antistatic layer,
Since the coating solution of the release agent may be repelled by the antistatic agent, the antistatic layer is preferably provided on the surface opposite to the release layer. Therefore, it is preferable to select an antistatic agent so that the surface specific resistance shows the surface specific resistance not only on the antistatic layer but also on the surface opposite to the antistatic layer (that is, the surface of the release layer).

As such an antistatic agent, for example,
Various cationic antistatic agents having cationic groups such as quaternary ammonium salts, pyridinium salts, and tertiary to tertiary amino groups, anions such as sulfonate groups, sulfate ester groups, phosphate ester groups, and phosphonate groups Various surfactants such as anionic antistatic agents having a functional group, amphoteric antistatic agents such as amino acids and aminosulfates, and nonionic antistatic agents such as amino alcohols, glycerin and polyethylene glycol. And an antistatic agent, and a high molecular weight antistatic agent obtained by increasing the molecular weight of the above antistatic agent. Further, a monomer or oligomer having a tertiary amino group or a quaternary ammonium group and capable of being polymerized by ionizing radiation, for example, an N, N-dialkylaminoalkyl (meth) acrylate monomer,
Polymerizable antistatic agents such as grade compounds can also be used. Of these, high molecular weight antistatic agents are particularly preferred.

In the antistatic layer, in addition to the antistatic resin composition, for improving the strength of the coating film of the antistatic layer, adhesion to the substrate film, water resistance, solvent resistance, blocking property and the like. Contains, as a binder, a thermoplastic resin such as a thermoplastic polyester resin, an acrylic resin, and a polyvinyl resin, and / or a polymer compound such as a thermosetting resin such as a thermosetting acrylic resin, a urethane resin, a melamine resin, and an epoxy resin. Preferably.

It is particularly preferable that the crosslinking agent contains at least one of methylolated or alkylolated melamine-based, urea-based, glyoxal-based, acrylamide-based compounds, epoxy compounds, and polyisocyanates.

The method for forming the antistatic layer on the surface of the substrate film is not particularly limited, but a coating method is preferably used. For example, coating methods include air doctor coating, knife coating, rod coating, forward rotation roll coating, reverse roll coating, gravure coating, kiss coating, bead coating, slit orifice coating, and cast coating. Is mentioned.

The drying temperature of the antistatic layer is 60 to 1
The temperature may be in the range of 50 ° C, preferably in the range of 80 to 130 ° C. If the drying temperature is lower than 60 ° C., the curing time is prolonged, and the productivity is undesirably reduced.

The polyester base film used in the present invention may be provided with an easy-adhesion layer for the purpose of improving the adhesion to the release layer. Particularly preferably, an easy-adhesion layer is provided before the final stretching step during film formation. Also,
In order to improve the adhesion between the polyester base film and the release layer, a surface treatment such as a corona treatment, a flame treatment, and an electron beam irradiation may be performed.

In the release polyester film of the present invention, it is necessary that the number of protrusions having a protrusion height of 0.27 μm or more and less than 0.54 μm on the release layer surface is 100 / mm ² or more. Preferably, the number is 200 / mm ² or more. 10
If the number is less than 0 / mm ² , scratches and scraping occur during the production and processing of the film, and defects are generated in the green sheet, which is not preferable. The upper limit of the number of protrusions having a protrusion height of 0.27 μm or more and less than 0.54 μm is not restricted, but is 1
If the number is larger than 000 / mm ² , the surface roughness is increased, and the green sheet is disadvantageous in that defects due to projections on the film surface occur, which is not preferable.

In the release polyester film of the present invention, it is necessary that protrusions having a protrusion height of 0.54 μm or more are 5.0 protrusions / mm ² or less on the surface of the release layer. Preferably, the number is 3.0 / mm ² or less. When the number of protrusions having a protrusion height of 0.54 μm or more on the surface of the release layer is more than 5.0 / mm ² , defects are generated in the green sheet, which is not preferable.

Further, in the release polyester film of the present invention, it is necessary that substantially no protrusion having a protrusion height of 0.81 μm or more is present on the surface of the release layer. The term “substantially free of protrusions” means that no more than ^two protrusions per 20 mm ^{2 of} measurement area, that is, 0.00 when the measurement area is converted to 1 mm ^2.
The density of one or less protrusions. The protrusion height is 0.
The presence of the projections of 81 μm or more is not preferable because defects occur in the green sheet.

Further, in the release polyester film of the present invention, the three-dimensional average surface roughness SRa of the release layer surface needs to be 0.010 μm to 0.030 μm. If the three-dimensional average surface roughness SRa is less than 0.010 μm, scratches and scraping occur during the production and processing of the film. Therefore, these cause defects in the green sheet, which is not preferable. On the other hand, if the three-dimensional average surface roughness SRa exceeds 0.030 μm, it is not preferable because defects resulting from protrusions on the film surface occur on the green sheet.

The release polyester film of the present invention is characterized in that the surface of the release layer has scratches and scratches on the surface of the release layer by setting the relationship between the height and the number of the protrusions and the three-dimensional surface roughness SRa within a specific range. Shaving can be reduced. Further, the heat shrinkage in the longitudinal direction of the polyester base film at 150 ° C. is 2.0% or less, preferably 1.5% or less, and the heat shrinkage in the longitudinal direction at 200 ° C. is 3.0.
% Or more, preferably 4.0% or more, and more preferably 5.0% or more.
When the content is 0% or more, scratches and abrasion on the release layer surface can be further reduced.

In order to set the heat shrinkage of the polyester base film at 150 ° C. to 2.0% or less and the heat shrinkage at 200 ° C. to 3.0% or more, the temperature and time during the heat setting treatment are set. In addition to optimizing the heat treatment, it is preferable to perform the longitudinal relaxation treatment at a temperature lower than the maximum temperature of the heat setting treatment.

If the heat shrinkage in the longitudinal direction of the polyester base film at 200 ° C. is less than 3.0%, it is easy to cause scratches and shavings during the manufacturing process and the working process, which is not preferable. Further, if the heat shrinkage in the longitudinal direction at 150 ° C. of the polyester base film exceeds 2.0%, the heat history in the processing step tends to deteriorate the flatness, which is not preferable.

When polylactic acid is used as the polyester, the longitudinal heat shrinkage at 120 ° C. is preferably 5.0% or less. More preferably, it is 4.0% or less. If the heat shrinkage in the longitudinal direction at 120 ° C. is more than 5.0%, the flatness tends to be disturbed in the processing step, which is not preferable.

[0064]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to only these examples. In addition, the evaluation method of a film is as follows.

(1) Three-dimensional surface roughness SRa The surface of the release layer of the release polyester film was measured by a stylus type three-dimensional surface roughness meter (SE-3AK, manufactured by Kosaka Laboratory Co., Ltd.).
With a needle radius of 2 μm, a load of 30 mg, and a needle speed of 0.1 mm / sec, measurement was performed over a measurement length of 1 mm with a cutoff value of 0.25 mm in the longitudinal direction of the film, and 500 points were measured at a pitch of 2 μm. And the height of each point was taken into a three-dimensional roughness analyzer (TDA-21).
The same operation is continuously performed 150 times at intervals of 2 μm in the width direction of the film, that is, 0.3 m in the width direction of the film.
m, and the data was taken into the analyzer.
Next, the three-dimensional average surface roughness SRa was determined using an analyzer.

(2) Number of protrusions After aluminum was thinly vapor-deposited on the film surface, the entire surface of 20 mm ² was scanned at 800 times magnification using a ^two- beam interference microscope (light source: thallium, wavelength: 0.54 μm). The number of projections having interference fringes was determined, and the number of projections was converted to the number per 1 mm ² to obtain the number of projections. New observed
In the ton ring, the single ring has a protrusion height of 0.27 μm.
Above 0.54 μm, a double ring or more corresponds to a projection height of 0.54 μm or more, and a triple ring or more corresponds to 0.81 μm.
m or more.

(3) Heat Shrinkage A sample having a width of 10 mm and a length of 250 mm was cut out in the longitudinal direction of the film, marked at intervals of 200 mm, and marked with 5 g.
The interval A is measured at a constant tension of. Subsequently, at 120 ° C., 150
℃, or no load in an oven in an atmosphere of 200 ℃,
It was left at the above temperature for 30 minutes. After taking out of the oven and cooling to room temperature, the interval B was determined at a constant tension of 5 g, and the heat shrinkage was determined by the following equation. The measurement of the heat shrinkage in the longitudinal direction of the film was performed at n = 3, and the average value was rounded off to the third decimal place and rounded to the second decimal place. The intervals A and B were read by a ruler at intervals of 0.25 mm. Heat shrinkage (%) = [(AB) / A] × 100

(4) ΔNx The refractive index in the longitudinal direction, width direction and thickness direction of the film was measured using Abbe refractometer 4T or 1T manufactured by Atago Optical Co., Ltd., and ΔNx was determined from the following equation. ΔNx = Nx− (Ny + Nz) / 2

(5) Area Ratio of Inactive Particles to Circumscribed Circle Inactive particles were scanned with a scanning electron microscope (S-5, manufactured by Hitachi, Ltd.).
Observed with 10 type), enlarged copy of what was photographed,
Further tracing was performed, and 200 particles were randomly painted black. Twenty particles were arbitrarily selected from this trace image, and the projected cross-sectional area of each particle was measured by an image analyzer (Nireco Corporation, Luzex IID). Further, by calculating the area of a circle circumscribing each particle, the area ratio was obtained using the following equation. Area ratio (%) to circumscribed circle = projected cross-sectional area of particle / area of circle circumscribed to particle × 100

(6) Average Particle Diameter of Inert Particles and Degree of Variation in Particle Size The inert particles were examined by a scanning electron microscope (S-5, manufactured by Hitachi, Ltd.).
Observed with 10 type), enlarged copy of what was photographed,
Further tracing was performed, and 200 particles were randomly painted black. This image was measured for the Feret diameter in the horizontal direction using an image analyzer (Nireco Corporation, Luzex IID), and the average value was used as the average particle diameter used in the following equation. The degree of dispersion of the particle diameter was calculated by the following equation. Variation (%) = (standard deviation of particle diameter / average particle diameter)
× 100 average particle diameter (μm) = sum of Feret diameters of each particle in the horizontal direction / number of particles measured

(7) Evaluation of scratches and scraping during film processing 100 parts by weight of an addition-reaction silicone resin (KS-778, manufactured by Shin-Etsu Chemical Co., Ltd .; toluene solution having a solid content of 30% by weight) as a release agent And 1 part by weight of a platinum catalyst (manufactured by Shin-Etsu Chemical Co., Ltd .; PL-50T) were dissolved in toluene to prepare a toluene solution having a total solid content of 3% by weight (coating solution for release layer). . Using this coating solution, 6 g / m ²
(Based on the amount of the coating solution), the mixture was heated and dried at 120 ° C. for 1 minute and subjected to an addition polymerization reaction to obtain a release polyester film having a release layer formed on one surface. This release polyester film is slit into a narrow width to form a tape, and the release layer surface is rubbed against a metal guide roll to form a tape.
The vehicle traveled 1000 m at a speed of 0 m / min. The amount of scratches generated in the release layer of the release polyester film after rubbing of the guide rolls and the amount of white powder generated on the surface of the guide rolls were evaluated and ranked according to the following five grades, respectively.

(A) Scratches Grade 1; Scratches are fairly frequent Grade 2; Scratches are frequent Grade 3; Scratches are slightly present Grade 4; There are almost no scratches Grade 5; No scratches occur

(B) Sharpness 1st grade; very much white powder is generated 2nd grade; white powder is frequently generated 3rd grade: white powder is slightly generated 4th grade: almost no white powder is generated 5th grade: white powder is generated None

(8) Evaluation of Green Sheet A ceramic slurry was applied to the release layer surface of the release polyester film prepared in the above (5) so as to have a thickness after drying of 3 μm, and dried at 120 ° C. for 1 minute. . The ceramic slurry was prepared by mixing a solvent (toluene), a ceramic raw material (manufactured by Fuji Titanium, BaTiO ₃ ), a binder, a plasticizer, and the like, forming a paste, and then dispersing and adjusting the mixture using a ball mill. The green sheet was irradiated with light from the opposite side to a range of an area of 600 cm ² , the occurrence of pinholes was observed, and a three-step evaluation was performed. Grade 1: There are many pinholes. Level 2; almost no pinholes Level 3; no pinholes

(9) Intrinsic viscosity The intrinsic viscosity was determined from the solution viscosity at 30 ° C. in a mixed solvent of 1,1,2,2-tetrachloroethane / phenol (weight ratio: 40/60).

Example 1 When the temperature of the esterification reactor reached 200 ° C.,
86.4 parts by weight of terephthalic acid and 64.6 parts by weight of ethylene glycol are charged, and while stirring, 0.017 part by weight of antimony trioxide, 0.064 part by weight of magnesium acetate tetrahydrate, and 0.1 part by weight of triethylamine are used as a catalyst. 1
6 parts by weight were charged. Subsequently, the temperature was increased under pressure to perform an esterification reaction under a condition of a gauge pressure of 0.34 MPa and 240 ° C., and then the esterification reactor was returned to normal pressure, and 0.014 parts by weight of trimethyl phosphate was added. . Further, the temperature was raised to 260 ° C. over 15 minutes, and trimethyl phosphate 0.012
Parts by weight were added. Then, after 15 minutes, a dispersion treatment was performed with a high-pressure disperser, and an aqueous solution of sodium tripolyphosphate was added to the calcium carbonate particles in an amount of 0.2 as sodium atom.
% Of a calcite-type synthetic calcium carbonate particle having an average particle diameter of 0.80 μm, which was subjected to a filtration treatment with a metal filter having a mesh size of 5 μm by cutting a coarse particle portion by 35% by centrifugation. 1.0 part by weight was added as the particle content. After 15 minutes, the obtained esterification reaction product was transferred to a polycondensation reactor,
A polycondensation reaction is carried out at 0 ° C under reduced pressure, and the intrinsic viscosity is 0.62 dl.
/ G of polyethylene terephthalate resin (A).
(Hereinafter abbreviated as PET (A))

On the other hand, in the production of PET (A),
An intrinsic viscosity of 0.62 containing no calcium carbonate particles.
dl / g of polyethylene terephthalate resin (B) was obtained. (Hereinafter, abbreviated as PET (B).)

The PET (A) and the PET (B) were dried in a vacuum and mixed at different mixing ratios so as to obtain the particle contents shown in Table 1. This was melted at 290 ° C., and the molten PET mixture was filtered using a filter capable of removing 95% of 4 μm particles, extruded from a T-die, and brought into close contact with a casting drum having a surface temperature of 30 ° C. by an electrostatic charge. I got

The unstretched film was heated at 90 ° C. with a ceramic roll and stretched 3.5 times in the longitudinal direction. Furthermore, it is 95 ° C to 150 ° C in the width direction with a tenter.
Stretched 4.2 times while raising the film temperature to 215
C. to perform heat setting. After that, a 3% relaxation treatment was performed in the width direction while cooling to 150 ° C. Further, when the film temperature reached 140 ° C., the film was cut at the end of the tenter, cut off from the clip, and conveyed to a film winding step at a speed 1% slower than the tenter speed. Table 2 shows the physical properties of the obtained film.

Example 2 In Example 1, the heat setting temperature was set at 235 ° C.
After 3% relaxation in the width direction while cooling to 0 ° C, when the film temperature reaches 50 ° C, the film is cut at the end of the tenter, cut off from the clip, and transported to the film winding process at the same speed as the tenter speed. The procedure was the same except for the above. Table 2 shows the physical properties of the obtained film.

Comparative Example 1 In Example 1, the silica particles shown in Table 1 were used in place of the calcium carbonate particles, and the opening of the filter used after the polyester polymerization was set to 10 μm. 10μm filter to be used
Was performed in the same manner except that a filter capable of removing 95% of the particles was used. Table 2 shows the physical properties of the obtained film.

Comparative Example 2 PET (A) was prepared in the same manner as in Example 1 except that the content of calcium carbonate was 0.03 parts by weight with respect to the polyester.
The procedure was performed in the same manner as in Example 1 except that the mixing ratio of PET and PET (B) was changed. Table 2 shows the physical properties of the obtained film.

Example 3 Poly-L-lactic acid 10 having a weight average molecular weight of 200,000
1 part by weight of the same calcium carbonate particles as those used in Example 1 was melt-kneaded at 210 ° C. with respect to 0 part by weight, and the calcium carbonate particles were dispersed and filtered through a metal filter having an aperture of 5 μm. Was. This calcium carbonate particle-containing poly-L-lactic acid and a poly-
L-lactic acid was mixed so that the particle content was 0.20 parts by weight. Next, after melting at 210 ° C. and filtering the molten poly-L-lactic acid using a filter capable of removing 95% of 4 μm particles, the molten poly-L-lactic acid was extruded from a T-die, and was brought into close contact with a 30 ° C. casting drum by an electrostatic charge, and was not drawn A film was obtained. The unstretched film is heated to 70 ° C.
It was heated with a ceramic roll and stretched 3.0 times in the longitudinal direction. Further, the film was stretched 6.0 times while raising the film temperature from 68 ° C. to 78 ° C. in the width direction with a tenter, and heated to 150 ° C. to perform a heat setting treatment. Thereafter, while cooling to 130 ° C., a 3% relaxation treatment was performed in the width direction. Further, when the film temperature reached 120 ° C., the film was cut at the end of the tenter, cut off from the clip, and conveyed to a film winding step at a speed 1% slower than the tenter speed. Table 2 shows the physical properties of the obtained film.

[0084]

[Table 1]

[0085]

[Table 2]

[0086]

The release polyester film of the present invention comprises:
Defects such as pinholes due to film surface protrusions do not occur on the green sheet used for forming green sheets for ceramic capacitors, and defects in the green sheet caused by scratches and scraping of the film surface generated during the manufacturing process and processing process Can be suppressed, so that it can be suitably used especially for a very thin green sheet having a thickness of 3 μm.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Harunobu Kuroiwa 2-8-8 Dojimahama, Kita-ku, Osaka-shi, Osaka F-term in Toyobo Co., Ltd. 4F071 AA45 AA46 AB21 AE17 AF27 AF58 AH19 BA01 BB06 BB08 BC01 BC14 BC15 BC16 4G052 DA05 DB02

Claims (5)

[Claims] 1. A release polyester film having a release layer provided on at least one surface of a polyester base film, wherein the number of protrusions on the release layer surface is 0.27 μm or more and less than 0.54 μm. Is 100 pieces / mm ² or more,
5.0 / mm ² or less projections with a projection height of 0.54 μm or more, substantially no projections with a projection height of 0.81 μm or more, and a three-dimensional average surface roughness SRa of 0.010 to 0 .
A release polyester film having a thickness of 030 μm. 2. The polyester base film according to claim 1, wherein
2. The release polyester film according to claim 1, wherein the heat shrinkage in the longitudinal direction at 0 ° C. is 2.0% or less, and the heat shrinkage in the longitudinal direction at 200 ° C. is 3.0% or more. 3. The polyester base film is made of polyethylene terephthalate or polyester mainly composed of polyethylene terephthalate.
The release polyester film as described in the above. 4. The release polyester film according to claim 1, wherein the polyester base film mainly comprises polylactic acid. 5. The polyester base film according to claim 5, wherein
The release polyester film according to claim 4, wherein the heat shrinkage at 0 ° C is 5.0% or less.