WO2023026800A1

WO2023026800A1 - Release film, method for manufacturing release film, and ceramic capacitor

Info

Publication number: WO2023026800A1
Application number: PCT/JP2022/029725
Authority: WO
Inventors: 一仁宮宅; 竜太竹上; 忠伊藤; 悠樹豊嶋; 泰雄江夏
Original assignee: 富士フイルム株式会社
Priority date: 2021-08-26
Filing date: 2022-08-03
Publication date: 2023-03-02
Also published as: KR20240035552A; JPWO2023026800A1; TW202313349A

Abstract

The present invention addresses the problem of providing: a release film that has excellent release properties of a ceramic green sheet, and excellent defect rate suppression of a ceramic capacitor even when transported at high speed; a method for manufacturing the release film; and a ceramic capacitor.　This release film comprises a release layer, a polyester base material, and a particle-containing layer in this order. The particle-containing layer contains particles and a non-polyester resin, the particles include organic particles, and the release layer includes a silicone compound.

Description

Release film, release film manufacturing method, ceramic capacitor

The present invention relates to a release film, a release film manufacturing method, and a ceramic capacitor.

As electronic devices become more sophisticated and smaller, electronic components used in electronic devices are also required to have higher performance and smaller sizes. Among electronic components, for example, multilayer ceramic capacitors are mounted on substrates in increasing numbers, and there is a strong demand for miniaturization.
In the manufacture of ceramic capacitors, it is common to apply a ceramic slurry onto a release film having a release layer and dry it to form a ceramic green sheet. In addition, in order to prevent the surface and the back surface of the release film from sticking (blocking) when the release film is wound, a method such as adding particles to the surface of the release film opposite to the release layer. It is also common to provide unevenness by .

In the release film used for manufacturing the ceramic green sheet, there is known a technique for improving the release stability by setting the release layer surface to a specific Si element ratio.
For example, in Patent Document 1, a polyester film is used as a substrate, the substrate has a surface layer A that does not substantially contain particles on at least one side, and a release layer is provided on the surface of the surface layer A on at least one side is laminated, the release layer is formed by curing a composition containing a binder component and a silicone-based release agent, and the release layer surface has a specific Si element ratio and maximum protrusion height (P) and area average roughness (Sa) are disclosed.

WO2020/050081

On the other hand, with the rapid miniaturization of ceramic capacitors in recent years, there is a demand for even thinner ceramic green sheets. On the other hand, it is considered that the more the thickness of the ceramic green sheet is reduced, the greater the influence of the surface shape of the release film on the performance of the ceramic green sheet. For example, if the peeling surface of the release film has an uneven shape, the uneven shape is transferred to the ceramic green sheet and the thickness of the ceramic green sheet fluctuates, possibly deteriorating the performance of the ceramic capacitor product.

The present inventors produced a ceramic green sheet using the release film for producing a ceramic green sheet described in Patent Document 1, and produced a ceramic capacitor using the obtained ceramic green sheet. Although the peelability of the ceramic capacitor is excellent, when the release film is transported at high speed in the release film manufacturing process such as the release layer coating process or the transport process, defective products with deteriorated electrical characteristics of the resulting ceramic capacitor may occur. We have found that there is room for further improvement.
In addition, when the above release film is stored for a long period of time and then used to produce a ceramic green sheet, the obtained ceramic green sheet may have uneven defects, and it has been found that there is room for further improvement. .
Moreover, in the release film, it is also required that the produced ceramic green sheet has excellent release properties.

In view of the above circumstances, the present invention provides a ceramic green sheet that is excellent in releasability and is manufactured using the obtained ceramic green sheet even when the ceramic green sheet is manufactured using a release film that is conveyed at high speed. An object of the present invention is to provide a release film capable of suppressing the defect rate of a capacitor and suppressing the occurrence of uneven defects in the obtained ceramic green sheet even when the ceramic green sheet is produced using the release film stored for a long period of time. .
Another object of the present invention is to provide a release film manufacturing method and a ceramic capacitor.

As a result of intensive studies aimed at solving the above problems, the inventors found that the above problems can be solved with the following configuration.

(1) A release film comprising a release layer, a polyester base material, and a particle-containing layer in this order, wherein the particle-containing layer contains particles and a non-polyester resin, the particles contain organic particles, and the release layer comprises silicone A release film containing a compound.
(2) The release film according to (1), which is used for producing ceramic green sheets.
(3) The release film according to (1) or (2), wherein the polyester base material is substantially free of particles.
(4) The surface of the particle-containing layer opposite to the polyester substrate has protrusions, and the proportion of the protrusions formed by the organic particles is 50 to 100% (1) to (3). Release film according to any one of.
(5) The surface of the particle-containing layer opposite to the polyester substrate has protrusions, and among the protrusions, the protrusions having the maximum protrusion height Sp are protrusions formed by organic particles, (1) to ( The release film according to any one of 4).
(6) The surface free energy of the surface of the release layer opposite to the polyester substrate is 10 to 30 mJ/m ² and the maximum projection height Sp is 1 to 30 nm, (1) to (5) ), the release film according to any one of
(7) The release film according to any one of (1) to (6), wherein the organic particles contain at least one selected from the group consisting of styrene resins, urethane resins, acrylic resins, and divinylbenzene resins.
(8) The surface free energy of the surface of the particle-containing layer opposite to the polyester substrate is 25 to 45 mJ/m ² and the maximum protrusion height Sp is 25 to 1000 nm, (1) to ( The release film according to any one of 7).
(9) The release film according to any one of (1) to (8), wherein the non-polyester resin is at least one resin selected from the group consisting of acrylic resins, urethane resins, and olefin resins.
(10) The release film according to any one of (1) to (9), which has a thickness of 40 μm or less.
(11) The release film according to any one of (1) to (10), wherein the particle-containing layer has a thickness of 1 to 500 nm.
(12) A method for producing a release film according to any one of (1) to (11), comprising:
A method for producing a release film, comprising the step of applying a particle-containing layer-forming composition containing organic particles and non-polyester cattle onto one surface of a polyester substrate.
(13) A ceramic capacitor manufactured using the release film according to any one of (1) to (11).

According to the present invention, even when a ceramic green sheet is produced using a release film that is excellent in peelability of the ceramic green sheet and conveyed at high speed, the defect rate of the ceramic capacitor produced using the obtained ceramic green sheet can be reduced. It is possible to provide a release film that can suppress the occurrence of unevenness defects in the resulting ceramic green sheet even when a ceramic green sheet is produced using the release film that has been stored for a long period of time.
Further, according to the present invention, a method for producing a release film and a ceramic capacitor can be provided.

It is a sectional view showing an example of composition of a release film concerning the present invention.

Hereinafter, embodiments of the present invention will be described in detail. It should be noted that the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the purpose of the present invention.

In this specification, a numerical range represented by "to" means a range including the numerical values before and after "to" as lower and upper limits. In the numerical ranges described stepwise in this specification, the upper limit or lower limit described in a certain numerical range may be replaced with the upper limit or lower limit of another numerical range described stepwise. Moreover, in the numerical ranges described in this specification, the upper limit or lower limit described in a certain numerical range may be replaced with the values shown in the examples.
As used herein, the amount of each component in the composition means the total amount of the multiple substances present in the composition unless otherwise specified when there are multiple substances corresponding to each component in the composition. do.
In this specification, the term "step" includes not only independent steps, but also if the intended purpose of the step is achieved even if it cannot be clearly distinguished from other steps. be
In this specification, a combination of two or more preferred aspects is a more preferred aspect.

As used herein, the term "longitudinal direction" refers to the longitudinal direction of the release film when the release film is manufactured, and is synonymous with the "conveyance direction" and the "machine direction."
As used herein, "width direction" means a direction perpendicular to the longitudinal direction. In this specification, "perpendicular" is not limited to strictly perpendicular, but includes substantially perpendicular. The term “substantially orthogonal” means intersecting within the range of 90°±5°, preferably intersecting within the range of 90°±3°, more preferably intersecting within the range of 90°±1°. .
Moreover, in this specification, "film width" means the distance between both ends of the release film in the width direction.

[Release film]
The release film of the present invention (hereinafter also simply referred to as "release film") comprises a release layer, a polyester base material, and a particle-containing layer in this order, the particle-containing layer containing particles and a non-polyester resin, contains organic particles and the release layer contains a silicone compound.

The configuration of the release film will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view showing an example of the configuration of a release film. The release film 1 includes a release layer 2, a polyester base material 4, and a particle-containing layer 6 in this order. In the release film 1 shown in FIG. 1, the surface 21 of the release layer 2 opposite to the polyester substrate 4 (hereinafter also referred to as “release surface”) and the particle-containing layer 6 opposite to the polyester substrate 4 It has two main surfaces consisting of side surfaces 61 (hereinafter also referred to as “conveying surfaces”).
In addition, the release film of the present invention is not limited to the embodiment shown in FIG. The release film may have intermediate layers, for example, between the release layer 2 and the polyester substrate 4 and/or between the polyester substrate 4 and the particle-containing layer 6 .

A feature of the release film of the present invention is that the particle-containing layer contains particles and a non-polyester resin, the particles contain organic particles, and the release layer contains a silicone compound.
Since the release film has the above characteristics, the release property of the ceramic green sheet is excellent, and even when the ceramic green sheet is produced using the release film conveyed at high speed, the ceramic produced using the resulting ceramic green sheet It has excellent performance in suppressing the defect rate of capacitors, and also has excellent performance in suppressing the occurrence of uneven defects in the ceramic green sheets obtained even when ceramic green sheets are manufactured using release films that have been stored for a long time. Although the detailed mechanism is not necessarily clear, the present inventors presume as follows.

When the release layer contains a silicone compound, the surface free energy of the release film is lowered, so it is considered that the release property of the ceramic green sheet is excellent.
When the release film is conveyed under high-speed conditions, the particles forming the projections on the conveying surface may drop off due to the impact caused by contact with the conveying rolls, and adhere to the conveying rolls. When the release layer contains a silicone compound, the release surface is likely to be charged, so it is conceivable that particles adhering to the transport roll or the like may adhere to the release film. Further, when the release film transported at high speed is stored in a roll form, it is conceivable that the particles adhering to the transport surface may adhere to the release surface facing the transport surface. When a ceramic green sheet is produced using a release film in which particles are attached to the release surface in this way, the ceramic green sheet is formed in contact with the release surface to which the particles are attached, so the particles migrate to the surface of the ceramic green sheet. put away. When such a ceramic green sheet is used to produce a ceramic capacitor, the particles are interposed between the laminated ceramic layers, so that minute recesses or protrusions are formed in the ceramic layers. It is presumed that the minute concave portions or convex portions formed between the ceramic layers in this way cause deterioration of the characteristics of the capacitor.
To solve this problem, the release film according to the present invention is characterized in that the particles present on the conveying surface of the release film are organic particles. As a result, even if the particles fall off and intervene between the ceramic green layers through the above process, the organic particles are burned in the firing process, so that minute recesses or protrusions are formed between the ceramic layers. As a result, the deterioration of the electrical characteristics of the multilayer ceramic capacitor can be suppressed, and the percentage of defective products whose electrical characteristics do not meet the standards of practicality (defect rate) among the manufactured multilayer ceramic capacitors can be suppressed. it is conceivable that.

In addition, the polyester base material included in the release film contains impurities such as oligomers, and when the release film is stored for a long period of time, precipitates due to the above impurities may be deposited on the transport surface and / or release surface of the release film. May appear. Here, the oligomer is a low-molecular-weight by-product produced during polymerization of the polyester resin, and is a component contained as an impurity in the polyester base material. By the precipitate appearing on the release surface as described above, or by the particles of the precipitate appearing on the transport surface migrating to the release surface by the same mechanism as described above during transport of the release film or roll storage, It is presumed that fine unevenness defects occurred in the ceramic green sheet formed on the peeled surface.
In order to solve this problem, the release film according to the present invention has a particle-containing layer that constitutes the transport surface containing a non-polyester resin, and a release layer that constitutes the release surface contains a silicone compound. Presumably, this suppresses the precipitation of impurities such as oligomers from the polyester base material onto the conveying surface and/or the release surface of the release film, thereby suppressing the occurrence of uneven defects in the ceramic green sheet formed on the release surface.
Hereinafter, in the present specification, even when a ceramic green sheet is produced using a release film conveyed at high speed, the performance of suppressing the defect rate of the ceramic capacitor produced using the obtained ceramic green sheet is excellent, and / Or, even when a ceramic green sheet is produced using a release film stored for a long time, the fact that the resulting ceramic green sheet has excellent performance of suppressing the occurrence of uneven defects is simply referred to as "the effect of the present invention is excellent." may be described.

Each layer of the release film will be described below. A method for manufacturing the release film and a method for manufacturing each layer will be described later.

<Release layer>
The release layer is a layer provided on the side opposite to the side of the polyester base material on which the particle-containing layer is provided, and the ceramic green sheet is formed on the release surface, which is the surface of the release layer opposite to the polyester base material. . That is, a ceramic green sheet is manufactured to be peelable on the peeling surface of the peeling film.
The release layer may be provided directly on the surface of the polyester base material, or may be provided on the polyester base material via another layer. It is preferable to provide
As a method of forming a release layer having a crosslinked structure, a method of forming a release layer using a release layer-forming composition containing a cross-linking agent can be mentioned, as described later.

[Silicone compound]
The release layer contains a silicone compound because of its excellent releasability.
The silicone compound contained in the release layer is not particularly limited as long as it is a compound having a siloxane bond in the molecule, but is preferably a silicone resin, more preferably a silicone resin having a crosslinked structure.
A silicone resin means a resin having a silicone structure (main chain composed of siloxane bonds) in its molecule. Examples of silicone resins include curable silicone resins, silicone graft resins, and modified silicone resins such as alkyl-modified silicone resins, with reactive curable silicone resins being preferred.
Examples of reactive curable silicone resins include addition reaction silicone resins, condensation reaction silicone resins, and ultraviolet or electron beam curable silicone resins. Among them, addition reaction type silicone resins having low-temperature curability or UV or electron beam curing type silicone resins are preferable because the release layer can be formed at a low temperature.

Examples of addition reaction silicone resins include resins obtained by reacting and curing polydimethylsiloxane having a terminal or side chain introduced with a vinyl group and hydrogen siloxane using a platinum catalyst.
As the condensation reaction silicone resin, for example, a three-dimensional polydimethylsiloxane having terminal OH groups and a polydimethylsiloxane having terminal H groups are subjected to a condensation reaction using an organic tin catalyst. Examples thereof include resins having a crosslinked structure.
Ultraviolet or electron beam curing silicone resins include those that utilize the same radical reaction as silicone rubber cross-linking, those that are photocured by introducing unsaturated groups, and those that decompose onium salts with ultraviolet rays or electron beams to generate strong acids. However, those that are crosslinked by cleaving epoxy groups and those that are crosslinked by addition reaction of thiol to vinylsiloxane are exemplified. More specific examples include acrylate-modified polydimethylsiloxane and glycidoxy-modified polydimethylsiloxane.

One of the silicone resins contained in the release layer may be used alone, or two or more of them may be used.
The content of the silicone resin in the release layer is preferably 0.1 to 99.9% by mass, more preferably 0.5 to 99.5% by mass, based on the total mass of the release layer.

[Resins other than silicone compounds]
The release layer may contain a resin other than the silicone compound (hereinafter also referred to as "another resin").
Other resins contained in the release layer are not particularly limited, but from the point of view of further improving release properties, it is preferable that the release layer further contains fluorine resins, alkyd resins, acrylic resins, various waxes, and aliphatic olefins.
Also, unsaturated polyester resins, melamine resins, epoxy resins, phenol resins, urethane resins, and the like may be used in combination.

Other resins contained in the release layer may be used singly or in combination of two or more.
When the release layer contains another resin, the content of the other resin in the release layer is preferably 50 to 99% by mass, more preferably 60 to 98% by mass, based on the total mass of the release layer. The rest of the release layer excluding the silicone resin and other resins is the additives described later, and the solvent, polymerization initiator, catalyst, etc. contained in the release layer forming composition (described later) used to form the release layer. It may be at least one of the residues.

[Additive]
The release layer may contain additives in addition to the above resins. As additives, additives such as light release additives and heavy release additives for adjusting the release force, adhesion improvers, and antistatic agents may be added.

[Properties of release layer]
(thickness)
The thickness of the release layer may be set according to the purpose of use, and is not particularly limited, but is preferably 5 to 2000 nm, more preferably 10 to 1000 nm, in terms of excellent balance between release performance and smoothness of the release surface. 30 to 300 nm is more preferred, and 50 to 200 nm is particularly preferred.
The thickness of the release layer is determined by preparing a section having a cross section perpendicular to the main surface of the release film and using a scanning electron microscope (SEM) or a transmission electron microscope (TEM). Arithmetic mean value of 5 thicknesses of the section measured.

(Surface free energy of peeled surface)
The surface free energy of the surface (release surface) of the release layer on the side opposite to the polyester substrate side is preferably 30 mJ/m ² or less, more preferably 10 to 30 mJ/m ² , in terms of better release properties of the ceramic green sheet. Preferably, 10 to 24 mJ/m ² is more preferable, and 10 to 20 mJ/m ² is particularly preferable.
The surface free energy of the release surface can be adjusted by the type of resin forming the release layer and additives. In particular, since the release layer of the release film of the present invention contains a silicone compound, the surface free energy is small and the release property of the ceramic green sheet is excellent.

The surface free energy of the peeled surface was measured using a contact angle meter (for example, "DROPMASTER-501" manufactured by Kyowa Interface Science Co., Ltd.) at 25 ° C. on the peeled surface with purified water, methylene iodide and ethylene. It is obtained by dropping a droplet of glycol, measuring the contact angle one second after the droplet adheres to the surface, and calculating from each obtained contact angle according to the method of Kitazaki and Hata.
The "surface free energy" obtained by the above method is the sum of the polar component and the hydrogen bond component of the surface free energy.

(Maximum protrusion height Sp of peeled surface, surface average roughness Sa)
The release surface is preferably as smooth as possible in order to smooth the functional layer such as a ceramic green sheet formed on the release layer. Specifically, the maximum protrusion height Sp of the peeled surface is preferably 1 to 60 nm, more preferably 1 to 40 nm, and even more preferably 1 to 30 nm.
The surface average roughness Sa of the peeled surface is preferably 0 to 10 nm, more preferably 0 to 5 nm, still more preferably 0 to 2 nm, and particularly preferably 0 to 1 nm.
The maximum protrusion height Sp and surface average roughness Sa of the release surface are determined, for example, by not putting particles in the release layer when providing the release layer, and by selecting the resin and additives that form the release layer. Adjustable. In particular, by providing a release layer containing a silicone compound on a polyester base material that does not substantially contain particles, smoothness is improved and Sp and Sa can be reduced.

In addition, the maximum projection height Sp and the surface average roughness Sa of the peeled surface are measured using an optical interferometer ("Vertscan R3300G Lite" manufactured by Hitachi High-Tech Co., Ltd.) under the following conditions. It is obtained by analyzing with the data analysis software provided.
In the measurement of the maximum projection height Sp, the measurement position is changed and measured five times, and the maximum value of the obtained measurement values is taken as the measurement value of the maximum projection height Sp (indicated as P in the built-in data analysis software) ). In addition, in the measurement of the surface average roughness Sa, the measurement position is changed and the measurement is performed five times, and the average value of the obtained measurement values is used as the measurement value of the surface average roughness Sa. Specific measurement conditions are as follows.
Measurement mode: WAVE mode Objective lens: 50x Measurement area: 186 μm × 155 μm

<Polyester base material>
A polyester substrate is a film-like body containing a polyester resin as the main polymer component. Here, the "main polymer component" means the polymer with the highest content (mass) among all polymers contained in the film-like substance.
The polyester base material may contain a single polyester resin, or may contain two or more polyester resins.

[Polyester resin]
A polyester resin is a polymer having an ester bond in its main chain. A polyester resin is usually formed by polycondensing a dicarboxylic acid compound and a diol compound, which will be described later.
The polyester resin is not particularly limited, and known polyester resins can be used. Examples of polyester resins include polyethylene terephthalate (PET), polyethylene-2,6-naphthalate (PEN), polypropylene terephthalate (PPT), polybutylene terephthalate (PBT), and copolymers thereof. At least one selected from the group consisting of PET, PEN, and copolymers thereof is preferred, and PET is more preferred.

The intrinsic viscosity of the polyester resin is preferably 0.50 dl/g or more and less than 0.80 dl/g, more preferably 0.55 dl/g or more and less than 0.70 dl/g.
The melting point (Tm) of the polyester resin is preferably 220 to 270°C, more preferably 245 to 265°C.
The glass transition temperature (Tg) of the polyester resin is preferably 65-90°C, more preferably 70-85°C.

The method for producing the polyester resin is not particularly limited, and known methods can be used. For example, a polyester resin can be produced by polycondensing at least one dicarboxylic acid compound and at least one diol compound in the presence of a catalyst.
The materials used for the production of polyester and the production conditions are described below.

(Dicarboxylic acid compound)
Examples of dicarboxylic acid compounds include dicarboxylic acids such as aliphatic dicarboxylic acid compounds, alicyclic dicarboxylic acid compounds, and aromatic dicarboxylic acid compounds, and dicarboxylic acids such as methyl ester compounds and ethyl ester compounds of these dicarboxylic acids. esters. Among them, aromatic dicarboxylic acid or methyl aromatic dicarboxylate is preferable.

Examples of aliphatic dicarboxylic acid compounds include malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, dimer acid, eicosandioic acid, pimelic acid, azelaic acid, methylmalonic acid, and ethylmalonic acid.
Alicyclic dicarboxylic acid compounds include, for example, adamantanedicarboxylic acid, norbornenedicarboxylic acid, cyclohexanedicarboxylic acid, and decalinedicarboxylic acid.

Examples of aromatic dicarboxylic acid compounds include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 1,8-naphthalenedicarboxylic acid. , 4,4′-diphenyldicarboxylic acid, 4,4′-diphenyletherdicarboxylic acid, 5-sodium sulfoisophthalic acid, phenylindanedicarboxylic acid, anthracenedicarboxylic acid, phenanthenedicarboxylic acid, and 9,9′-bis(4- carboxyphenyl)fluoric acid and their methyl esters.
Among them, terephthalic acid or 2,6-naphthalenedicarboxylic acid is preferable, and terephthalic acid is more preferable.

Only one type of dicarboxylic acid compound may be used, or two or more types may be used in combination. When terephthalic acid is used as the dicarboxylic acid compound, terephthalic acid may be used alone, or may be copolymerized with another aromatic dicarboxylic acid such as isophthalic acid, or an aliphatic dicarboxylic acid.

(Diol compound)
Examples of diol compounds include aliphatic diol compounds, alicyclic diol compounds, and aromatic diol compounds, with aliphatic diol compounds being preferred.

Examples of aliphatic diol compounds include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,2-butanediol, 1,3-butanediol, and neo Pentyl glycol may be mentioned, with ethylene glycol being preferred.
Alicyclic diol compounds include, for example, cyclohexanedimethanol, spiroglycol, and isosorbide.
Examples of aromatic diol compounds include bisphenol A, 1,3-benzenedimethanol, 1,4-benzenedimethanol, and 9,9′-bis(4-hydroxyphenyl)fluorene.
Only one kind of diol compound may be used, or two or more kinds thereof may be used in combination.

(catalyst)
The catalyst used for producing the polyester resin is not particularly limited, and any known catalyst that can be used for synthesizing the polyester resin can be used.
Examples of catalysts include alkali metal compounds (e.g., potassium compounds, sodium compounds), alkaline earth metal compounds (e.g., calcium compounds, magnesium compounds), zinc compounds, lead compounds, manganese compounds, cobalt compounds, aluminum compounds, antimony. compounds, titanium compounds, germanium compounds, and phosphorus compounds. Among them, titanium compounds are preferable from the viewpoint of catalytic activity and cost.
Only one kind of catalyst may be used, or two or more kinds thereof may be used in combination. at least one metal catalyst selected from potassium compounds, sodium compounds, calcium compounds, magnesium compounds, zinc compounds, lead compounds, manganese compounds, cobalt compounds, aluminum compounds, antimony compounds, titanium compounds, and germanium compounds; It is preferable to use a compound together, and it is more preferable to use a titanium compound and a phosphorus compound together.

As the titanium compound, an organic chelate titanium complex is preferred. An organic chelate titanium complex is a titanium compound having an organic acid as a ligand.
Organic acids include, for example, citric acid, lactic acid, trimellitic acid, and malic acid.
As the titanium compound, titanium compounds described in [0049] to [0053] of Japanese Patent No. 5575671 can also be used, and the contents of the above publications are incorporated herein.

(Terminal blocking agent)
In the production of the polyester resin, if necessary, a terminal blocker may be used. By using the terminal blocking agent, a structure derived from the terminal blocking agent is introduced to the terminal of the polyester resin.
The terminal blocking agent is not limited, and known terminal blocking agents can be used. Examples of terminal blocking agents include oxazoline-based compounds, carbodiimide-based compounds, and epoxy-based compounds.
As the end blocking agent, the content described in [0055] to [0064] of JP-A-2014-189002 can also be referred to, and the content of the above publication is incorporated herein.

(manufacturing conditions)
The reaction temperature for producing the polyester resin is not limited, and may be appropriately set according to the raw materials. The reaction temperature is preferably 260-300°C, more preferably 275-285°C.
The pressure in producing the polyester resin is not limited, and may be appropriately set according to the raw material. The pressure is preferably 1.33×10 ⁻³ to 1.33×10 ⁻⁵ MPa, more preferably 6.67×10 ⁻⁴ to 6.67×10 ⁻⁵ MPa.

As a method for synthesizing the polyester resin, the method described in [0033] to [0070] of Japanese Patent No. 5575671 can also be used, and the contents of the above publication are incorporated herein.

[Content of each component]
The content of the polyester resin in the polyester base is preferably 85% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and 98% by mass with respect to the total mass of the polymer in the polyester base. % or more is particularly preferred.
The upper limit of the content of the polyester resin is not particularly limited, and can be appropriately set, for example, within a range of 100% by mass or less with respect to the total mass of the polymer in the polyester base material.
When the polyester base material contains polyethylene terephthalate, the content of polyethylene terephthalate is preferably 90 to 100% by mass, more preferably 95 to 100% by mass, based on the total mass of the polyester resin in the polyester base material. 100% by mass is more preferred, and 100% by mass is particularly preferred.

The polyester base material may contain components other than the polyester resin (eg, catalyst, unreacted raw material components, particles, water, etc.).
From the viewpoint of improving the smoothness of the release film, it is preferable that the polyester base material does not substantially contain particles. Examples of the particles include particles contained in the particle-containing layer described below.
"Substantially free of particles" means that the content of particles is 50 mass with respect to the total mass of the polyester base material when quantitatively analyzing the elements derived from the particles by fluorescent X-ray analysis for the polyester base material. It is defined as ppm or less, preferably 10 mass ppm or less, more preferably detection limit or less. This is because even if the particles are not actively added to the polyester base material, contaminants derived from foreign substances, raw material resins, or stains attached to the lines or equipment in the manufacturing process of the polyester base material are peeled off, This is because they may be mixed into the base material.

[Properties of polyester base material]
(orientation)
Preferably, the polyester substrate is a biaxially oriented polyester substrate.
"Biaxial orientation" means the property of having molecular orientation in two axial directions. The molecular orientation is measured using a microwave transmission type molecular orientation meter (for example, MOA-6004, manufactured by Oji Scientific Instruments Co., Ltd.). The angle formed by the two axial directions is preferably within the range of 90°±5°, more preferably within the range of 90°±3°, and still more preferably within the range of 90°±1°. The biaxially oriented polyester substrate in the release film of the present invention preferably has molecular orientation in the longitudinal direction and the width direction. A biaxially oriented polyester substrate can be produced by the method described later.

(density)
The density of the polyester base material is preferably 1.39 to 1.41 g/cm ³ , more preferably 1.395 to 1.405 g/cm ³ and even more preferably 1.398 to 1.400 g/cm ³ .
The density of the polyester base material can be measured using an electronic hydrometer (product name “SD-200L”, manufactured by Alpha Mirage).

(thickness)
The thickness of the polyester base material is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 40 μm or less, from the viewpoint of being able to control the releasability. Although the lower limit of the thickness is not particularly limited, it is preferably 3 µm or more, more preferably 10 µm or more, and even more preferably 20 µm or more in terms of improving strength and workability.
The thickness of the polyester base material should be measured using a continuous stylus type film thickness meter. Specifically, the thickness of the polyester base material is measured over 10 m along the longitudinal direction with a continuous stylus film thickness gauge. This measurement is performed at five different positions in the width direction. Let the arithmetic average value of the obtained measured value be thickness.

<Particle-containing layer>
A particle-containing layer refers to a layer containing particles.
The particle-containing layer is a layer provided on the surface of the polyester substrate opposite to the side on which the release layer is provided, and can improve the transportability of the release film. Specifically, the winding quality can be improved (blocking can be suppressed), the occurrence of scratches and defects during transportation can be suppressed, and wrinkles during high-speed transportation can be reduced.
The particle-containing layer may be provided directly on the surface of the polyester base material, or may be provided on the surface of the polyester base material via another layer. It is preferable to provide

Moreover, the particle-containing layer preferably contains a binder, and may further contain an additive.
The particles, binders and additives are described below.

(particle)
The particle-containing layer contains organic particles as particles. Thereby, the defect rate of the ceramic capacitor can be suppressed.
The particle-containing layer may also contain inorganic particles, but when manufacturing a ceramic capacitor using a ceramic green sheet formed on the peeling surface, it reduces the number of particles that do not burn and fall off, and is excellent in suppressing the defect rate of the ceramic capacitor. In addition, the smaller the number of inorganic particles, the better. Specifically, the transport surface, which is the surface of the particle-containing layer opposite to the polyester base material, has protrusions, and among the protrusions observed on this transport surface, the proportion of protrusions formed by organic particles is the number of protrusions. The ratio is preferably 50 to 100%, more preferably 70 to 100%.

The particles forming the protrusions are analyzed by observing the transport surface with a scanning electron microscope (SEM, "S-4800", manufactured by Hitachi High-Tech Co., Ltd.). Specifically, the conveying surface is observed with an SEM at a magnification such that 15 to 20 protrusions are within the observation field (however, 20,000 times is the upper limit magnification, and if there are 15 or more protrusions, Arbitrary 15 particles are discriminated between organic particles and inorganic particles). At this time, even if dust and/or coarsely aggregated particles of 1 μm or more are present, the dusts and coarsely aggregated particles are not counted. For the particles observed in that area, EDS (Energy Dispersive X-ray Spectroscopy, energy dispersive X-ray) analysis equipment is used to analyze the elements that form each particle, and determine whether it is an organic particle or an inorganic particle. do. The ratio of the number of organic particles to the total number of particles observed in the above measurement area is calculated, this is performed for 10 fields of view, and the arithmetic average value is taken as the ratio of protrusions formed by organic particles.
In addition, based on the results of elemental analysis of the particles, when the total content of inorganic elements (for example, Si) excluding monovalent inorganic elements such as Na is 1% by mass or more, it is determined as an inorganic particle, If the content of inorganic elements is less than 1% by mass, the particles are determined to be organic particles.

In addition, in terms of being excellent in suppressing the defect rate of the ceramic capacitor as described above, the transport surface has protrusions, and among the protrusions observed on the transport surface, the protrusions having the maximum protrusion height Sp are formed of organic particles. It is preferable that the projection is
A method for determining whether or not the protrusions having the maximum protrusion height Sp on the conveying surface of the release film are protrusions formed of organic particles will be described in detail in Examples described later.

Resin particles are preferable as the organic particles contained in the particle-containing layer. Examples of the resin constituting the resin particles include acrylic resins such as polymethyl methacrylate resin (PMMA), polyester resins, silicone resins, and styrene-acrylic resins. The resin particles may have a crosslinked structure. Examples of resin particles having a crosslinked structure include urethane crosslinked particles, acrylic crosslinked particles, and divinylbenzene crosslinked particles.
The organic particles preferably contain at least one selected from the group consisting of styrene resins, urethane resins, acrylic resins, and divinylbenzene resins, and are selected from the group consisting of styrene resins, urethane resins, and acrylic resins. It is more preferred to include at least one
In addition, in this specification, an acrylic resin means a resin containing structural units derived from acrylate or methacrylate.

Examples of commercially available acrylic resin particles include Eposter (registered trademark) MX020W, MX030W, MX050W, MX100W, MX200W, and MX300W (manufactured by Nippon Shokubai Co., Ltd.), and Techpolymer (registered trademark) series (Sekisui Plastics Co., Ltd.). manufactured by Kogyo Co., Ltd.).
Examples of commercially available styrene resin particles include Nipol (registered trademark) UFN1008 (manufactured by Nippon Zeon Co., Ltd.).
Examples of commercial products of urethane resin particles include Artpearl (registered trademark) C-1000T and MM110SMA (manufactured by Negami Kogyo Co., Ltd.).

The average particle size of the organic particles contained in the particle-containing layer is not particularly limited, and is preferably 1 nm to 3 μm, more preferably 40 nm to 2 μm, and more preferably 50 nm to 1 μm.
The shape of the particles is not particularly limited, and examples thereof include rice grain-like, spherical, cubic, spindle-like, scale-like, aggregated, and irregular shapes. Aggregate means a state in which primary particles are aggregated. Although the shape of the aggregated particles is not limited, spherical or irregular shapes are preferred.

The particles contained in the particle-containing layer may be used singly, or two or more kinds of particles may be used.
When the particle-containing layer contains two or more kinds of particles having different particle diameters, the particle-containing layer preferably contains at least one kind of particles having an average particle diameter within the above range, and two or more kinds of particles having different particle diameters. More preferably, all of the particles have an average particle size within the above range.

The content of the particles in the particle-containing layer is preferably 0.1 to 30% by mass, preferably 1 to 25% by mass, based on the total mass of the particle-containing layer, from the viewpoints of transportability and coating properties of the release layer. More preferably, 1 to 15% by mass is even more preferable.
Also, the content of the particles is preferably 0.0001 to 0.01% by mass, more preferably 0.0005 to 0.005% by mass, relative to the total mass of the polyester base material.

(Non-polyester resin (binder))
The particle-containing layer contains a non-polyester resin. The non-polyester resin contained in the particle-containing layer functions as a binder.
Non-polyester resins are not particularly limited as long as they are resins other than polyester resins, and include acrylic resins, urethane resins, olefin resins, polyvinyl alcohol resins, and acrylonitrile-butadiene resins. , an acrylic resin, a urethane resin, or an olefin resin is preferable.
Here, non-polyester resins (especially acrylic resins, urethane resins and olefin resins) and polyester resins have different solubility parameters (SP values). In other words, the compatibility between the polyester resin and the acrylic resin, urethane resin, and olefin resin is insufficient, so that impurities such as oligomers are less likely to deposit on the conveying surface from the polyester base material via the particle-containing layer. It is speculated that this makes it difficult for projections due to impurities contained in the polyester base material to occur on the conveying surface.

Non-polyester resins such as acrylic resins, urethane resins, and olefin resins are not particularly limited, and known resins can be used.
The non-polyester resin may be an acid-modified resin.
Moreover, the particle-containing layer may contain a polyester resin.

The acrylic resin is a resin containing structural units derived from (meth)acrylate, and may be copolymerized with a vinyl monomer such as styrene. Although the acrylic resin is not particularly limited, it preferably contains a structural unit derived from a (meth)acrylate having an alkyl group having 1 to 12 carbon atoms, and a (meth)acrylate having an alkyl group having 1 to 8 carbon atoms. It is more preferable to contain structural units derived from.
The acrylic resin may have an acid-modified component. The acrylic resin may contain a structural unit derived from (meth)acrylic acid as an acid-modified component. In addition, (meth)acrylic acid may form an acid anhydride, or may be neutralized with at least one selected from alkali metals, organic amines and ammonia.

The acid value of the acrylic resin is preferably 30 mgKOH/g or less, more preferably 20 mgKOH/g or less. The lower limit of the acid value is not particularly limited, and is, for example, 0 mgKOH/g, but is preferably 2 mgKOH/g or more from the viewpoint of coating as an aqueous dispersion. By setting the acid value of the acrylic resin in the above range and / or containing a structural unit derived from a (meth)acrylate having an alkyl group having 1 to 12 carbon atoms, the resin is more difficult to be compatible with the polyester resin. It is possible to further suppress the deposition of impurities such as oligomers contained in the polyester base material in the particle-containing layer, thereby further suppressing defects in the ceramic green sheet.

The olefin resin may be any resin containing a structural unit derived from an olefin in its main chain. By having a structural unit derived from an olefin in the main chain, it is possible to make the resin difficult to be compatible with the polyester resin, and the deposition of impurities such as oligomers contained in the polyester base material in the particle-containing layer is suppressed. Defects in ceramic green sheets can be suppressed.
The olefin is not particularly limited, but is preferably an alkene having 2 to 6 carbon atoms, more preferably ethylene, propylene or hexene, and still more preferably ethylene.
The olefin-derived structural units of the polyolefin are preferably 50 to 99 mol %, more preferably 60 to 98%, of all the structural units of the polyolefin.

As the olefin resin, an acid-modified olefin resin is preferable. Examples of acid-modified olefin resins include copolymers obtained by modifying the above olefin resins with an acid-modifying component such as an unsaturated carboxylic acid or an anhydride thereof.

Commercially available acid-modified olefin resins include, for example, Zaixen (registered trademark) series such as Zaixen AC, A, L, NC and N (manufactured by Sumitomo Seika Co., Ltd.), Chempearl S100, S120, S200, S300, S650. and Chemipearl (registered trademark) series such as SA100 (manufactured by Mitsui Chemicals, Inc.), Hitec (registered trademark) series such as Hitec S3121 and S3148K (manufactured by Toho Chemical Co., Ltd.), Arrow Base SE-1013, SE-1010, Arrowbase (registered trademark) series such as SB-1200, SD-1200, SD-1200, DA-1010 and DB-4010 (manufactured by Unitika Ltd.), Hardren AP-2, NZ-1004 and NZ-1005 (Toyobo (manufactured by Sumitomo Seika Co., Ltd.), and Sepulsion G315 and VA407 (manufactured by Sumitomo Seika Chemicals Co., Ltd.).
Acid-modified olefin resins described in [0022] to [0034] of JP-A-2014-076632 can also be preferably used.

The urethane resin is not limited as long as it is a polymer having a urethane bond, and known urethane resins such as reaction products of isocyanate compounds and polyol compounds can be used.
The urethane resin is preferably a urethane resin having an acidic group, or a form containing a urethane resin and a dispersing agent, since it is easy to form a film by coating. A carboxyl group etc. are mentioned as an acidic group.
Urethane resin, for example, by adjusting the structure and hydrophobicity (hydrophilicity) of each of the polyol compound and / or isocyanate compound as a raw material, it can be a resin that is difficult to be compatible with the polyester resin, the polyester base material Precipitation of impurities such as oligomers contained in is suppressed in the particle-containing layer, and defects in the ceramic green sheet can be suppressed. The urethane resin preferably contains a polyester structure in that defect suppression can be further improved.
Commercially available urethane resins include, for example, Hydran (registered trademark) AP-20, AP-40N and AP-201 (manufactured by DIC Corporation), Takelac (registered trademark) W-605, W-5030 and W-5920. (above, manufactured by Mitsui Chemicals), Superflex (registered trademark) 210 and 130, and Elastron (registered trademark) H-3-DF, E-37 and H-15 (above, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) mentioned.

The non-polyester resin contained in the particle-containing layer may have a crosslinked structure. That is, the particle-containing layer may be a crosslinked film.
In order to form a non-polyester resin having a crosslinked structure, a method of forming a particle-containing layer using a particle-containing layer-forming composition containing a crosslinking agent can be used, as described later.

The particle-containing layer may contain a single binder, or may contain two or more binders. Moreover, the particle-containing layer may contain a single non-polyester resin, or may contain two or more non-polyester resins.
From the viewpoint of suppressing defects, the content of the binder (preferably non-polyester resin) is preferably 30 to 99.8% by mass, more preferably 50 to 99.5% by mass, based on the total mass of the particle-containing layer. .

(Additive)
The particle-containing layer may contain additives other than the particles and binder described above.
Additives contained in the particle-containing layer include, for example, surfactants, waxes, antioxidants, ultraviolet absorbers, colorants, reinforcing agents, plasticizers, antistatic agents, flame retardants, rust inhibitors, and anti-rust agents. Examples include fungicides.

The particle-containing layer preferably contains a surfactant from the viewpoint of improving the smoothness of areas other than areas where protrusions formed by particles exist on the conveying surface.
The surfactant is not particularly limited, and includes silicone-based surfactants, fluorine-based surfactants, and hydrocarbon-based surfactants, among which hydrocarbon-based surfactants are preferred.

The silicone-based surfactant is not particularly limited as long as it has a silicon-containing group as a hydrophobic group, and examples thereof include polydimethylsiloxane, polyether-modified polydimethylsiloxane, and polymethylalkylsiloxane.
Examples of commercially available silicone surfactants include BYK (registered trademark)-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-347, BYK-348, and , BYK-349 (manufactured by BYK), and KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF-642, KF-643, KF-6020, X-22-4515, KF-6011, KF-6012, KF-6015, and KF-6017 (manufactured by Shin-Etsu Chemical Co., Ltd.).

The fluorosurfactant is not particularly limited as long as it has a fluorine-containing group as a hydrophobic group, and examples thereof include perfluorooctane sulfonic acid and perfluorocarboxylic acid.
Commercially available fluorosurfactants include, for example, Megafac (registered trademark) F-114, F-410, F-440, F-447, F-553, and F-556 (manufactured by DIC Corporation). ), and Surflon (registered trademark) S-211, S-221, S-231, S-233, S-241, S-242, S-243, S-420, S-661, S-651, and S-386 (manufactured by AGC Seimi Chemical Co., Ltd.) can be mentioned.
In addition, from the viewpoint of improving environmental suitability, the fluorine-based surfactant has a linear perfluoroalkyl group having 7 or more carbon atoms, such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). It is preferred to use surfactants derived from substitute materials for the compounds.

Examples of hydrocarbon surfactants include anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants.
Anionic surfactants include, for example, alkyl sulfates, alkylbenzene sulfonates, alkyl phosphates, and fatty acid salts.
Examples of nonionic surfactants include polyalkylene glycol mono- or dialkyl ethers, polyalkylene glycol mono- or dialkyl esters, and polyalkylene glycol mono- or dialkyl esters/monoalkyl ethers.
Cationic surfactants include primary to tertiary alkylamine salts and quaternary ammonium compounds.
Amphoteric surfactants include surfactants having both an anionic site and a cationic site in the molecule.

Examples of commercially available anionic surfactants include RAPISOL (registered trademark) A-90, A-80, BW-30, B-90, and C-70 (manufactured by NOF Corporation), NIKKOL (registered trademark) OTP-100 (manufactured by Nikko Chemical Co., Ltd.), Kohakul (registered trademark) ON, L-40, and Phosphanol (registered trademark) 702 (manufactured by Toho Chemical Industry Co., Ltd.) ), and Viewlite (registered trademark) A-5000 and SSS (manufactured by Sanyo Chemical Industries Co., Ltd.).
Commercially available nonionic surfactants include, for example, Naloacty (registered trademark) CL-95 and HN-100 (trade name: manufactured by Sanyo Chemical Industries, Ltd.), Resolex BW400 (trade name: KOKYU ALCOHOL KOGYO Co., Ltd.), EMALEX (registered trademark) ET-2020 (manufactured by Nippon Emulsion Co., Ltd.), and Surfynol (registered trademark) 104E, 420, 440, 465, and Dynol (registered trademark) 604, 607 (manufactured by Nissin Chemical Industry Co., Ltd.).

Among hydrocarbon surfactants, anionic surfactants and/or nonionic surfactants are preferred, and anionic surfactants are more preferred.

The anionic hydrocarbon-based surfactant preferably has a plurality of hydrophobic terminal groups in terms of further improving smoothness. The hydrophobic end group may be part of the hydrocarbon group of the hydrocarbon surfactant. For example, a hydrocarbon surfactant terminated with a hydrocarbon group having a branched chain structure will have a plurality of hydrophobic end groups.
Examples of anionic hydrocarbon surfactants having multiple hydrophobic terminal groups include di-2-ethylhexyl sodium sulfosuccinate (having four hydrophobic terminal groups), di-2-ethyloctyl sodium sulfosuccinate ( 4 hydrophobic end groups) and branched alkyl benzene sulfonates (2 hydrophobic end groups).

One type of surfactant may be used, or two or more types may be used in combination.
When the particle-containing layer contains a surfactant, the content of the surfactant is preferably 0.1 to 10% by mass with respect to the total mass of the particle-containing layer. ~5% by mass is more preferred, and 0.5 to 2% by mass is even more preferred.

The wax is not particularly limited, and may be natural wax or synthetic wax. Natural waxes include carnauba wax, candelilla wax, beeswax, montan wax, paraffin wax, and petroleum wax. In addition, a slipping agent described in [0087] of International Publication No. 2017/169844 can also be used.
The wax content is preferably 0 to 10% by mass with respect to the total mass of the particle-containing layer.

[Properties of particle-containing layer]
(thickness)
The particle-containing layer is formed, for example, by coating a composition containing organic particles and a non-polyester resin on one surface of the polyester substrate, and often has a thickness of 1 μm or less.
Further, the polyester base material and the particle-containing layer, which will be described later, may be formed by co-extrusion molding, in which case the thickness of the particle-containing layer is often 1 to 10 μm.
The thickness of the particle-containing layer is preferably 1 nm to 3 μm, and when it is produced by coating, it is preferably 1 to 500 nm, more preferably 1 to 250 nm, even more preferably 10 to 100 nm, from the viewpoint of production suitability and haze reduction. 20 to 100 nm is particularly preferred.
The thickness of the particle-containing layer is measured using a scanning electron microscope (SEM) or a transmission electron microscope (TEM) by preparing a section having a cross section perpendicular to the main surface of the release film. Arithmetic mean value of thickness at 5 locations.

(Surface free energy of conveying surface)
The surface free energy of the surface (conveying surface) of the particle-containing layer opposite to the polyester substrate is preferably 25 to 60 mJ/m ² , more preferably 25 to 45 mJ/m ² , and further preferably 30 to 45 mJ/m ² . preferable.
When the surface free energy on the conveying surface is within the above range, deposition of impurities such as oligomers contained in the polyester base material on the conveying surface can be further suppressed, and defects in the ceramic green sheet can be further suppressed.

(Maximum protrusion height Sp of conveying surface, surface average roughness Sa)
Regarding the particle-containing layer, the maximum protrusion height Sp on the transport surface is preferably 10 to 5000 nm, the release film is excellent in high-speed transportability, and defects in the ceramic green sheet can be further suppressed, and the release film is transported at high speed. From the viewpoint of less occurrence of winding misalignment and better winding performance, the thickness is more preferably 25 to 1000 nm, still more preferably 25 to 600 nm, and particularly preferably 30 to 500 nm.
Further, the average surface roughness Sa on the conveying surface is preferably 0 to 10 nm, more preferably 0 to 5 nm, even more preferably 1 to 3 nm.
The method for measuring the maximum projection height Sp and the average surface roughness Sa of the conveying surface is the same as the method for measuring the maximum projection height Sp and the average surface roughness Sa of the peeling surface described above.

<Properties of release film>
[Thickness]
The thickness of the release film is preferably 100 µm or less, more preferably 50 µm or less, and even more preferably 40 µm or less, in terms of better releasability. Moreover, the thickness of the release film is preferably 3 μm or more, more preferably 10 μm or more, and even more preferably 20 μm or more, in order to improve strength and workability.

<Manufacturing method of release film>
A method for manufacturing a release film will be described.
The method for producing the release film is not particularly limited as long as the release film having the properties described above can be obtained, and known methods can be used.
Among them, the preferred method for producing a release film is the following in that the release film can be produced with high productivity.
An extrusion molding step of forming an unstretched polyester base material by extrusion;
A first stretching step of stretching an unstretched polyester substrate in one of the transport direction and the width direction to form a uniaxially oriented polyester substrate, and a uniaxially oriented polyester substrate in the transport direction and a stretching step in which a second stretching step of stretching in the other width direction to form a biaxially oriented polyester substrate is performed stepwise or simultaneously,
Between the extrusion molding step and the stretching step, between the first stretching step and the second stretching step, or after the stretching step, the particle-containing layer-forming composition is applied to one surface side of the polyester base material. a particle-containing layer forming step of forming a particle-containing layer;
Between the extrusion molding step and the stretching step, between the first stretching step and the second stretching step, or after the stretching step, the release layer forming composition is applied to the other surface side of the polyester base material and peeled. and a release layer forming step of forming a layer.
Hereinafter, embodiments of the preferred manufacturing method will be described in detail.

[Extrusion process]
The extrusion molding step is a step of forming an unstretched polyester base material by extrusion molding. More specifically, it is a step of extruding a molten resin containing a raw material polyester resin into a film to form an unstretched polyester base material. The raw material polyester resin is synonymous with the polyester resin described in the item (polyester resin) above.
In order to produce a polyester base material that does not substantially contain particles, it is preferable to use polyester pellets that do not contain particles at the time of extrusion molding.

The extrusion molding method is, for example, a method of molding a raw material resin into a desired shape by extruding a melt of the raw material resin using an extruder.
The melt extruded from the extrusion die is cooled to form a film. For example, the melt can be formed into a film by contacting the melt with a casting roll and cooling and solidifying the melt on the casting roll. In cooling the melt, it is preferable to blow air (preferably cool air) to the melt.

[Stretching process]
The stretching step includes a first stretching step of stretching an unstretched polyester substrate in either the transport direction or the width direction to form a uniaxially oriented polyester substrate, and a uniaxially oriented polyester substrate. in the other of the machine direction and the width direction to form a biaxially oriented polyester base material.
One of the first stretching step and the second stretching step is a longitudinal stretching step of stretching the polyester base material in the conveying direction (hereinafter also referred to as "longitudinal stretching"), and the other of the first stretching step and the second stretching step. is a lateral stretching step of stretching the polyester base material in the width direction (hereinafter also referred to as “lateral stretching”). During stretching, the polyester polymer is aligned in each direction.

The stretching step may be simultaneous biaxial stretching in which longitudinal stretching and lateral stretching are performed simultaneously, or sequential biaxial stretching in which longitudinal stretching and lateral stretching are performed in stages. Examples of the form of sequential biaxial stretching include longitudinal stretching→lateral stretching, longitudinal stretching→lateral stretching→longitudinal stretching, and longitudinal stretching→longitudinal stretching→lateral stretching, with longitudinal stretching→lateral stretching being preferred.
Hereinafter, the mode of longitudinal stretching→transverse stretching will be described, but the production method is not limited to this mode.

The draw ratio in the longitudinal drawing step is appropriately set, but is preferably 2.0 to 5.0 times, more preferably 2.5 to 4.0 times, and even more preferably 2.8 to 4.0 times.
The stretching speed in the longitudinal stretching step is preferably 800 to 1500%/second, more preferably 1000 to 1400%/second, even more preferably 1200 to 1400%/second. Here, the "stretching speed" is a value obtained by dividing the length Δd of the polyester substrate in the transport direction stretched per second in the longitudinal stretching step by the length d0 of the polyester substrate in the transport direction before stretching. , is the value expressed as a percentage.
In the longitudinal stretching step, it is preferable to heat the unstretched polyester base material. This is because longitudinal stretching is facilitated by heating.

In the lateral stretching step, it is preferable to preheat the uniaxially oriented polyester base material before lateral stretching. By preheating the uniaxially oriented polyester base material, the uniaxially oriented polyester base material can be easily laterally stretched.
The draw ratio (lateral draw ratio) in the width direction of the uniaxially oriented polyester base material in the transverse drawing step is not particularly limited, but is preferably larger than the draw ratio in the longitudinal drawing step. The draw ratio in the transverse drawing step is preferably 3.0 to 6.0 times, more preferably 3.5 to 5.0 times, even more preferably 3.5 to 4.5 times.
The stretching speed in the lateral stretching step is preferably 8 to 45%/second, more preferably 10 to 30%/second, even more preferably 15 to 20%/second.

[Particle-containing layer forming step]
The particle-containing layer forming step is a step of forming a particle-containing layer by applying a particle-containing layer-forming composition containing organic particles and a non-polyester resin to one surface of a polyester base material.
The particle-containing layer forming step is performed, for example, between the extrusion molding step and the first stretching step, between the first stretching step and the second stretching step, or after the stretching step.
The particle-containing layer formed on one surface of the polyester substrate in the particle-containing layer forming step has the same meaning as the layer described in the item of the particle-containing layer.
A mode of applying the composition for forming a particle-containing layer will be described below.

First, the composition for forming a particle-containing layer will be described.
The composition for forming the particle-containing layer can be prepared by mixing the organic particles contained in the particle-containing layer, the non-polyester resin, additives added as necessary, and the solvent.
Examples of solvents include water and alcohol solvents.

The particle-containing layer-forming composition may contain a single solvent, or may contain two or more solvents.
The content of the solvent is preferably 80 to 99.5% by mass, more preferably 90 to 99% by mass, based on the total mass of the composition for forming a particle-containing layer.
That is, in the particle-containing layer-forming composition, the total content of components (solid content) other than the solvent is preferably 0.5 to 20% by mass with respect to the total mass of the particle-containing layer-forming composition. ~10% by mass is more preferred.

The organic particles, non-polyester resin, and optional additives contained in the particle-containing layer-forming composition, including their preferred embodiments, are as described in the section on the particle-containing layer. be.
Regarding each component other than the solvent in the composition for forming a particle-containing layer, the content of each component relative to the total mass of the solid content of the composition for forming a particle-containing layer is preferably the content of each component relative to the total mass of the particle-containing layer. It is preferable to adjust the content of each component in the particle-containing layer-forming composition so as to be the same as the content.

Moreover, the composition for forming a particle-containing layer may contain a cross-linking agent.
The cross-linking agent is not particularly limited, and known ones can be used.
Examples of cross-linking agents include melamine-based compounds, oxazoline-based compounds, epoxy-based compounds, isocyanate-based compounds, and carbodiimide-based compounds, with oxazoline-based compounds and carbodiimide-based compounds being preferred. Examples of commercially available products include Carbodilite V-02-L2 (manufactured by Nisshinbo Corp.) and Epocross K-2020E (manufactured by Nippon Shokubai Co., Ltd.). For details of the epoxy-based compound, the isocyanate-based compound, and the melamine-based compound, reference can be made to [0081] to [0083] of JP-A-2015-163457. Cross-linking agents described in [0082] to [0084] of International Publication No. 2017/169844 can also be preferably used. As for the carbodiimide compound, the descriptions in [0038] to [0040] of JP-A-2017-087421 can be referred to.
For oxazoline-based compounds, carbodiimide-based compounds, and isocyanate-based compounds, cross-linking agents described in [0074] to [0075] of WO 2018/034294 can also be preferably used.
The content of the cross-linking agent is preferably 0 to 50% by mass with respect to the total mass of the particle-containing layer.
The weight ratio of the cross-linking agent to the binder in the particle-containing layer-forming composition is preferably 2 to 50% by weight.

The method of applying the particle-containing layer-forming composition is not particularly limited, and a known method can be used. Examples of coating methods include spray coating, slit coating, roll coating, blade coating, spin coating, bar coating and dip coating.

The particle-containing layer forming step is preferably performed between the first stretching step and the second stretching step.
The heating temperature for forming the particle-containing layer is preferably 180° C. or lower, more preferably 150° C. or lower, and even more preferably 120° C. or lower. The lower limit is not particularly limited, and may be 60°C or higher.

In addition, in order to improve the adhesion between the polyester base material and the particle-containing layer, before providing the particle-containing layer, the surface of the polyester base material is subjected to pretreatment such as anchor coating, corona treatment, and plasma treatment. may be applied.

[Peeling layer forming step]
The release layer forming step is a step of forming a release layer by applying a release layer forming composition to the surface of the polyester substrate opposite to the particle-containing layer.
The release layer forming step is performed between the extrusion molding step and the first stretching step, between the first stretching step and the second stretching step, or after the stretching step.
When the release layer forming step is performed after the stretching step, it is preferably performed after the cooling step described below, and more preferably after the winding step and trimming step described below.
The release layer formed on one surface of the polyester substrate in the release layer forming step has the same meaning as the layer described in the item of the release layer.

First, the release layer-forming composition will be described.
The release layer-forming composition can be prepared by mixing the silicone compound, the above-mentioned other resins that are added as necessary, additives that are added as necessary, and a solvent.
Examples of solvents include water, alcohol solvents, ether solvents, ketone solvents, and aromatic hydrocarbon solvents.

The release layer-forming composition may contain a single solvent, or may contain two or more solvents.
The content of the solvent is preferably 80 to 99.5% by mass, more preferably 90 to 99% by mass, based on the total mass of the release layer-forming composition.
That is, in the release layer-forming composition, the total content of components (solid content) other than the solvent is preferably 0.5 to 20% by mass, preferably 1 to 10%, based on the total mass of the release layer-forming composition. % by mass is more preferred.

The silicone compound, other resins, and optional additives contained in the release layer-forming composition, including their preferred embodiments, are as described in the release layer section above.
The release layer-forming composition contains the above resin and solvent, and if necessary, may contain the above additives and/or the above catalyst used for curing the resin.
Moreover, it is preferable that the release layer forming composition contains a cross-linking agent. The cross-linking agent is not particularly limited, and known ones can be used.
The release layer-forming composition may also contain a polymerization initiator. Examples of the polymerization initiator include photopolymerization initiators, and known ones can be used.
For each component other than the solvent in the release layer-forming composition, the content of each component relative to the total mass of solids in the release layer-forming composition is the preferred content of each component relative to the total mass of the release layer. It is preferable to adjust the content of each component in the release layer-forming composition so as to be the same.

The method of applying the release layer-forming composition is not particularly limited, and a known method can be used. A specific example of the coating method is as described in the particle-containing layer forming step.

The heating temperature for forming the release layer is preferably 180°C or lower, more preferably 150°C or lower, and even more preferably 120°C or lower. The lower limit is not particularly limited, and may be 60°C or higher.

In addition, in order to improve the adhesion between the polyester base material and the release layer, before providing the release layer, the surface of the polyester base material is subjected to pretreatment such as anchor coating, corona treatment, and plasma treatment. may

[Heat setting process]
The production method for the release film may include a heat setting step as a heat treatment for the polyester film obtained in the stretching step after the stretching step.
In the heat-setting step, the polyester film obtained by the stretching step can be heated and heat-set. By crystallizing the polyester resin by heat setting, shrinkage of the polyester base material can be suppressed.
The surface temperature (heat setting temperature) of the polyester film in the heat setting step is not particularly limited, but is preferably less than 240°C, more preferably 235°C or less, and even more preferably 230°C or less. Although the lower limit is not particularly limited, it is preferably 190°C or higher, more preferably 200°C or higher, and even more preferably 210°C or higher.
The heating time in the heat setting step is preferably 5 to 50 seconds, more preferably 5 to 30 seconds, even more preferably 5 to 10 seconds.

[Thermal relaxation step]
The method for producing the release film may include a heat relaxation step after the heat setting step.
In the thermal relaxation step, it is preferable to thermally relax the polyester film heat-set in the heat-setting step by heating at a temperature lower than that in the heat-setting step. Thermal relaxation can relax the residual strain of the polyester film.
The surface temperature (thermal relaxation temperature) of the polyester film in the heat relaxation step is preferably 5°C or more lower than the heat setting temperature, more preferably 15°C or more lower, still more preferably 25°C or more lower, and 30°C or higher. Lower temperatures are particularly preferred. That is, the thermal relaxation temperature is preferably 235°C or lower, more preferably 225°C or lower, still more preferably 210°C or lower, and particularly preferably 200°C or lower.
The lower limit of the thermal relaxation temperature is preferably 100°C or higher, more preferably 110°C or higher, and even more preferably 120°C or higher.

[Cooling process]
The method for producing the release film may include a cooling step of cooling the heat-relaxed polyester film.
In the above production method, the cooling rate of the polyester film in the cooling step is preferably more than 2000° C./min and less than 4000° C./min, more preferably 2000 to 3500° C./min, more than 2200° C./min and less than 3000° C./min. Preferably, 2300-2800° C./min is particularly preferred.
The cooling step preferably includes a step (expansion step) of expanding the thermally relaxed polyester film in the width direction.
The expansion rate of the polyester film in the width direction by the expansion step, that is, the ratio of the polyester film width at the end of the cooling process to the polyester film width before the start of the cooling process is preferably 0% or more, and more preferably 0.001% or more. Preferably, 0.01% or more is more preferable.
Although the upper limit of the expansion rate is not particularly limited, it is preferably 1.3% or less, more preferably 1.2% or less, and even more preferably 1.0% or less.

[Winding process]
The production method may have a winding step of obtaining a roll-shaped polyester film by winding the polyester film obtained through the above steps.

[Trimming process]
The manufacturing method further comprises a trimming step of continuously cutting the polyester film along the transport direction and cutting off at least one end in the width direction of the polyester film before performing the winding step. good too.

[Other conditions]
The transport speed of the polyester film in each step other than the longitudinal stretching step of the present production method is not particularly limited, but in the lateral stretching step, heat setting step, heat relaxation step, and cooling step, in terms of productivity and quality, 50 to 200 m/min is preferred, and 80 to 150 m/min is more preferred.

In the method for producing a release film specifically described above, a combination of two or more preferred aspects is a more preferred aspect.

In the method for producing a release film described above, a method of forming a particle-containing layer by applying a composition for forming a particle-containing layer in the step of forming a particle-containing layer has been described. is not limited to, and a known method can be used. For example, there is a method of forming an unstretched polyester substrate laminated with a particle-containing layer by coextrusion molding.
A method for producing a release film preferably includes a step of applying the particle-containing layer-forming composition to one surface of a polyester base material.

Further, in the method for producing a release film described above, the stretching step of stretching an unstretched polyester base material and/or the particle-containing layer forming step of forming a particle-containing layer on one surface of the polyester base material may be performed at the same time or before or after the shows an embodiment in which the peeling layer forming step is performed, but the timing of performing the peeling layer forming step is not limited to the above embodiment.
For example, after performing the extrusion molding step, the stretching step, and the particle-containing layer forming step to produce a laminated film having a polyester substrate and a particle-containing layer formed on one surface of the polyester substrate. , For the laminated film produced, as a release layer forming step, a release layer forming composition is applied to the surface of the polyester substrate opposite to the particle-containing layer to form a release layer. A release film can be made comprising, in that order, a layer, a polyester substrate and a release layer.

[Application of release film]
The release film is preferably used as a release film (carrier film) for producing a ceramic green sheet. A ceramic green sheet manufactured using the above-described release film can be suitably used for manufacturing ceramic capacitors for which multi-layered internal electrodes are required in accordance with miniaturization and increase in capacity.
A method for producing a ceramic green sheet using the release film is not particularly limited, and a known method can be used. A method for producing the ceramic green sheet includes, for example, a method in which a prepared ceramic slurry is applied to the release surface of the release film, and the solvent contained in the ceramic slurry is removed by drying.
The method of applying the ceramic slurry is not particularly limited. For example, a known method such as applying a ceramic slurry obtained by dispersing ceramic powder and a binder in a solvent by a reverse roll method and removing the solvent by heating and drying. method can be applied. The binder agent is not particularly limited, and examples thereof include polyvinyl butyral. Also, the solvent is not particularly limited, and examples thereof include ethanol and toluene.

The ceramic green sheets produced in this manner are used to produce ceramic capacitors. A known method can be applied as a method of manufacturing a ceramic capacitor using a ceramic green sheet, and examples thereof include the following method.
First, internal electrodes are provided by coating or printing a conductive paste on the laminate of the release film and the ceramic green sheets produced by the above method. Next, the release film is removed from the laminate of ceramic green sheets, the ceramic green sheets with internal electrodes are successively laminated, and the resulting laminate is pressed to produce an intermediate laminate. After cutting the intermediate laminate into a desired shape, the cut intermediate laminate is fired. Next, a ceramic capacitor is obtained by forming external electrodes electrically connected to the internal electrodes on the two end surfaces of the fired intermediate laminate using a conductive paste such as silver.

In addition, the release film of the present invention includes a protective film for dry film resist, a film for sheet molding such as a decorative layer and a resin sheet, a release film for process manufacturing such as a semiconductor manufacturing process, and a release film for a polarizing plate manufacturing process. , and can also be used as a separator for adhesive films for labels, medical and office supplies.

The present disclosure will be described more specifically below with examples. Materials, usage amounts, proportions, processing details, and processing procedures shown in the following examples can be changed as appropriate without departing from the scope of the present disclosure. Accordingly, the scope of the present disclosure is not limited to the specific examples provided below. "Parts" and "%" are based on mass unless otherwise specified.

[Example 1]
<Extrusion molding process>
Polyethylene terephthalate pellets were produced using a titanium compound described in Japanese Patent No. 5575671 (citric acid chelate titanium complex, VERTEC AC-420, manufactured by Johnson Matthey) as a polymerization catalyst. Specifically, 1 ton (1000 kg) of terephthalic acid, 390 kg of ethylene glycol, and 9 ppm by mass of Ti atoms with respect to polyethylene terephthalate, which produces a titanium compound, were mixed. The resulting mixture was continuously supplied to the reactor to carry out an esterification reaction. Furthermore, magnesium acetate tetrahydrate in an amount such that the Mg atom is 81 mass ppm relative to the polyethylene terephthalate produced, and trimethyl phosphate in an amount such that the P atom is 73 mass ppm relative to the polyethylene terephthalate produced. was added to the mixture to carry out a polycondensation reaction to produce polyethylene terephthalate pellets.
The obtained pellets were dried to a moisture content of 50 ppm or less, put into a hopper of a single-screw kneading extruder with a diameter of 30 mm, melted at 280° C. and extruded. The melt was passed through a filter (pore size of 3 μm) and then extruded from a die onto a cooling drum at 25° C. to obtain an unstretched polyester substrate made of polyethylene terephthalate. The extruded melt (melt) was brought into close contact with the cooling drum by an electrostatic application method.
The melting point (Tm) of polyethylene terephthalate constituting the unstretched polyester base material was 258°C, and the glass transition temperature (Tg) was 80°C.

<Longitudinal stretching process>
The unstretched film was subjected to a longitudinal stretching step by the following method.
A uniaxially oriented film was produced by passing the preheated unstretched film between two pairs of rolls having different circumferential speeds and stretching it in the machine direction (conveying direction) under the following conditions.
(Longitudinal stretching conditions)
Preheating temperature: 75°C
Stretching temperature: 90°C
Stretch ratio: 3.4 times Stretching speed: 1300%/sec

<Particle-containing layer forming step and release layer forming step>
On one side of the longitudinally stretched uniaxially oriented polyester substrate, the following composition A1 (particle-containing layer-forming composition) is applied with a bar coater, and the surface coated with the particle-containing layer of the uniaxially oriented polyester substrate. The composition L1 (composition for forming a release layer) is applied to the surface opposite to the side with a bar coater, and the formed coating film is dried with hot air at 100 ° C. to remove the particle-containing layer and the release. formed a layer. That is, composition A1 and composition L1 were in-line coated onto a uniaxially oriented polyester substrate. At this time, the coating amounts of the composition A1 and the composition L1 were adjusted so that the thickness of the particle-containing layer formed after the lateral stretching was 40 nm and the thickness of the release layer was 100 nm.

(Composition A1)
Composition A1 was prepared by mixing each component shown below. The prepared composition A1 was subjected to filtration treatment using a filter with a pore size of 6 μm (F20, manufactured by Mahle Filter Systems Co., Ltd.), and membrane degassing (2x6 radial flow superphobic, manufactured by Polypore Co., Ltd.). , the obtained composition A1 was applied to the surface of the uniaxially oriented film.
・Urethane resin 1 (Hydran (registered trademark) AP-40N, manufactured by DIC Corporation, an aqueous dispersion with a solid concentration of 25% by mass): 157 parts by mass ・Anionic hydrocarbon surfactant (Rapisol (registered Trademark) A-90, di-2-ethylhexyl sodium sulfosuccinate, manufactured by NOF Corporation, solid content concentration 1% by mass diluted with water): 56 parts by mass Organic particles O1 (crosslinked PMMA particles, Eposter (registered trademark) MX050W , Nippon Shokubai Co., Ltd., average particle diameter 70 nm, solid content concentration 10% by mass aqueous dispersion): 8 parts by mass, water: 779 parts by mass

(Composition L1)
Composition L1 was prepared by mixing each component shown below. Filtration treatment and membrane degassing in the same manner as composition A1 were performed on the prepared composition L1 to obtain composition L1.
・Silicone emulsion (DEHESIVE EM480, manufactured by Asahi Kasei Wacker Silicone Co., Ltd.): 20 parts by mass ・Silicone emulsion (CROSSLINKER V72, manufactured by Asahi Kasei Wacker Silicone Co., Ltd.): 3 parts by mass ・Silane coupling agent (KBM403, Shin-Etsu Chemical Co., Ltd. ( Co., Ltd.): 0.1 parts by mass, water: 77 parts by mass

<Lateral stretching process>
A biaxially oriented film was produced by stretching the polyester base material, which had undergone the longitudinal stretching step, the release layer forming step, and the particle-containing layer forming step, in the width direction using a tenter under the following conditions.
(Lateral stretching conditions)
Preheating temperature: 100°C
Stretching temperature: 120°C
Stretch ratio: 4.2 times Stretching speed: 50%/sec

<Heat setting process>
The biaxially oriented film subjected to the lateral stretching step was subjected to a heat setting step of heat setting the film by heating under the following conditions using a tenter.
(Heat fixation conditions)
Heat setting temperature: 227°C
Heat fixation time: 6 seconds

<Thermal relaxation process>
Then, the heat-set film was subjected to a heat relaxation step for relaxing the tension of the film by heating under the following conditions. Also, in the heat relaxation step, the film width was reduced compared to that at the end of the heat setting step by narrowing the distance (tenter width) between the gripping members of the tenter that grips both ends of the film. The following thermal relaxation rate Lr was obtained from the film width L2 at the end of the thermal relaxation process with respect to the film width L1 at the start of the thermal relaxation process by the formula Lr=(L1−L2)/L1×100.
(Thermal relaxation conditions)
Thermal relaxation temperature: 190°C
Thermal relaxation rate Lr: 4%

<Cooling process and expansion process>
A cooling step was performed on the thermally relaxed film under the following conditions. Further, in the cooling step, an expansion step was performed to expand the width of the film compared to that at the end of the thermal relaxation step by expanding the width of the tenter.
The following cooling rates were measured when the film surface temperature was measured when the film was transported into the cooling unit and when the film was transported out of the cooling unit, with the cooling time ta being the residence time from when the film was transported into the cooling unit of the stretching machine until it was transported out. It was obtained by dividing the temperature difference ΔT (°C) from the film surface temperature by the cooling time ta.
Further, the following expansion rate ΔL was obtained from the film width L3 at the end of the cooling process with respect to the film width L2 of the polyester film at the start of the cooling process by the formula ΔL = (L3 - L2) / L2 × 100.
(Cooling condition)
Cooling rate: 2500°C/min (extended condition)
Expansion rate ΔL: 0.6%

<Winding process>
Using a trimming device, the film cooled in the cooling step was continuously cut along the conveying direction at positions 20 cm from both ends in the width direction of the film to trim both ends of the film. Then, the film was wound up with a tension of 40 kg/m after extrusion processing (knurling) was performed on a region from both ends of the film to 10 mm in the width direction.
A release film was produced by the above method. The obtained release film had a thickness of 31 μm, a width of 1.5 m, and a winding length of 7000 m.

[Examples 2-9 and 12-13]
As shown in Table 1, the release films of Examples 2 to 9 and 12 to 13 were prepared in the same manner as in Example 1, except that the types of particles and resin in the particle-containing layer and the thickness of each layer were changed. made.
Composition A6 of Example 6 was obtained by replacing organic particles O1 in Example 4 with 6.7 masses of organic particles O2 (Eposter (registered trademark) MX100W, average particle diameter 150 nm, solid content concentration 10% by mass aqueous dispersion). part and organic particles O4 (Eposter (registered trademark) MX300W, average particle diameter 450 nm, solid content concentration 10% by mass aqueous dispersion) 1.3 parts by mass in the same manner as composition A4 of Example 4. prepared.
Composition A7 of Example 7 was obtained by replacing the organic particles O1 in Example 4 with 2.7 masses of organic particles O3 (Eposter (registered trademark) MX200W, average particle diameter 350 nm, solid content concentration 10% by mass aqueous dispersion). Part and inorganic particles I1 (Snowtex (registered trademark) MP-2040, manufactured by Nissan Chemical Co., Ltd., colloidal silica, average particle diameter 200 nm, adjusted to a solid content concentration of 10% by mass aqueous dispersion) Replaced with 5.3 parts by mass It was prepared in the same manner as composition A4 of Example 4, except that
Composition A8 of Example 8 was obtained by replacing the organic particles O1 in Example 4 with 6.7 masses of organic particles O2 (Eposter (registered trademark) MX100W, average particle diameter 150 nm, solid content concentration 10% by mass aqueous dispersion). part and organic particles O5 (Techpolymer (registered trademark) MB-4, manufactured by Sekisui Plastics Co., Ltd., average particle diameter 4 μm, aqueous dispersion adjusted to a solid content concentration of 10% by mass) 1.3 parts by mass. It was prepared in the same manner as composition A4 of Example 4, except that

In composition A12 of Example 12, the organic particles O1 in Example 4 were replaced with 7.0 parts by mass of organic particles O2 (Eposter (registered trademark) MX100W, average particle diameter 150 nm, solid content concentration 10% by mass aqueous dispersion). Inorganic particles I1 (Snowtex (registered trademark) MP-2040, manufactured by Nissan Chemical Co., Ltd., colloidal silica, average particle diameter 200 nm, adjusted to a solid content concentration of 10% by mass aqueous dispersion) Replaced with 1.0 parts by mass Except that, it was prepared in the same manner as composition A4 of Example 4.
Composition A13 of Example 13 was obtained by replacing the organic particles O1 in Example 4 with 6.0 parts by mass of organic particles O3 (Eposter (registered trademark) MX200W, average particle diameter 350 nm, solid content concentration 10% by mass aqueous dispersion). , Inorganic particles I2 (Snowtex (registered trademark) ZL, manufactured by Nissan Chemical Co., Ltd., colloidal silica, particle diameter 70 to 100 nm, adjusted to a solid content concentration of 10% by mass aqueous dispersion) 2.0 parts by mass Except that, it was prepared in the same manner as composition A4 of Example 4.

[Example 10]
A biaxially oriented film was prepared according to the method described in Example 1, except that no release layer was formed. The obtained film was unwound, and the following composition L2 was applied to the surface of the polyester substrate opposite to the particle-containing layer so that the thickness after curing was 500 nm. After the formed coating film was dried at 90° C., it was thermally cured by heating at 120° C. for 1 minute to form a release layer, thereby producing a release film.

(Composition L2)
Acrylic resin 2 (a copolymer obtained by polymerizing methyl methacrylate, stearyl methacrylate, 2-hydroxyethyl methacrylate, and methacrylic acid at a mass ratio of 47:26:20:7, solid content 40% by mass toluene solution):1. 75 parts by mass Polyester-modified silicone resin (BYK-370, manufactured by BYK-Chemie Japan Co., Ltd., solid content concentration 25% by mass): 0.05 parts by mass Thermally polymerizable compound (hexamethoxymelamine, Tokyo Chemical Industry Co., Ltd. product, solid content 100% by mass): 0.25 parts Acid catalyst (p-toluenesulfonic acid, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., solid content 100% by mass): 0.02 parts Methyl ethyl ketone: 58 Parts by mass Toluene: 40 parts by mass

[Example 11]
A release film was produced according to the method described in Example 10, except that composition L3 was used instead of composition L2 in the release layer forming step.
(Composition L3)
・Amino alkyd resin (Tesfine 305, Showa Denko Materials Co., Ltd., solid content 50% by mass): 2.0 parts by mass ・Polyester-modified silicone resin (BYK-370, manufactured by BYK-Chemie Japan Co., Ltd., solid content concentration 25 mass) %): 0.01 parts by mass Acid catalyst (p-toluenesulfonic acid, manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd., solid content 100% by mass): 0.02 parts by mass Methyl ethyl ketone: 58 parts by mass Toluene: 40 part by mass

[Comparative Example 1]
11 parts by mass of inorganic particles I1 (Snowtex (registered trademark) MP-2040, manufactured by Nissan Chemical Industries, Ltd., colloidal silica, average particle diameter 200 nm, solid content concentration 40% by mass aqueous dispersion) instead of organic particles O1 and that "Surflon (registered trademark) S-211" (manufactured by AGC Seimi Chemical Co., Ltd., fluorine-based surfactant) was used instead of "Rapisol A-90" as a surfactant. Composition CA1 was prepared according to the method for preparing composition A2 in Example 2.
Except for using the composition CA1 instead of the composition A1 in the particle-containing layer forming step, changing the thickness of the particle-containing layer, and changing the thickness of the release layer in the release layer forming step. prepared a release film according to the method described in Example 10.

[Comparative Example 2]
Using 8 parts by mass of organic particles O2 (crosslinked PMMA particles, Eposter (registered trademark) MX100W, manufactured by Nippon Shokubai Co., Ltd., average particle diameter 150 nm, solid content concentration 40% by mass aqueous dispersion) instead of inorganic particles I1, and , Instead of urethane resin 2, the copolymer polyester resin contained in the polyester water dispersion (Aw-1) prepared according to the method described in International Publication No. 2017/199774 was changed to Comparative Example 1. Composition CA2 was prepared according to the method for preparing composition CA1.
A release film was produced according to the method described in Comparative Example 1, except that the composition CA2 was used instead of the composition CA1 in the particle-containing layer forming step.

[Comparative Example 3]
A release film was produced according to the method described in Example 10, except that composition L4 was used instead of composition L2 in the release layer forming step.
(Composition L4)
· Amino alkyd resin (Tesfine 305, Showa Denko Materials Co., Ltd., solid content 50% by mass): 2.0 parts by mass · Acid catalyst (p-toluenesulfonic acid, Fuji Film Wako Pure Chemical Co., Ltd., solid content 100 % by mass): 0.02 parts by mass Methyl ethyl ketone: 58 parts by mass Toluene: 40 parts by mass

〔evaluation〕
The release films produced in each example and each comparative example were evaluated as follows.

<Defect Evaluation 1 of Ceramic Green Sheet>
Barium titanate powder (BaTiO ₃ ; manufactured by Sakai Chemical Industry Co., Ltd., product name “BT-03”) 100 parts by mass, polyvinyl butyral resin as a binder (manufactured by Sekisui Chemical Co., Ltd., product name “S-Lec (registered trademark) B・K BM-2”) 8 parts by mass, 4 parts by mass of dioctyl phthalate as a plasticizer (manufactured by Kanto Chemical Co., Ltd., dioctyl phthalate, deer 1st class), and a mixed solution of toluene and ethanol (mass ratio 6: 4) 135 parts by mass were mixed. A ceramic slurry was prepared by dispersing the mixture in the presence of zirconia beads using a ball mill and removing the beads from the resulting dispersion.

The release films obtained in each example and each comparative example were stored in an environment of normal temperature and normal humidity (25° C., 50% RH) for 1 week. The ceramic slurry was coated on the release surface of the release film after storage with a die coater over a width of 250 mm and a length of 10 m so that the film thickness after drying was 1 μm. After that, the resulting coating film was dried at 100° C. for 2 minutes in a dryer, and then wound into a roll. For the laminated film of the ceramic green sheet and the release film, a fluorescent lamp is illuminated from the release film side, and a 1 ^m2 area on the surface of all the molded ceramic green sheets is visually inspected to detect minute irregularities such as pinholes. was inspected for the presence of Based on the number of confirmed defects, defects on the surface of the ceramic green sheet were evaluated according to the following evaluation criteria.

(Evaluation criteria)
A: No rugged defects were observed on the surface of the ceramic green sheet.
B: Concavo-convex defects were observed on the surface of the ceramic green sheet.

<Defect Evaluation 2 of Ceramic Green Sheet>
The release films obtained in each example and each comparative example were stored for 3 months under a normal temperature and normal humidity environment. Defects on the surface of the ceramic green sheet were evaluated in the same manner as in defect evaluation 1, except that the release film after storage for 3 months was used.
(Evaluation criteria)
A: No irregularity defect was observed on the ceramic green sheet.
B: 1 to 10 uneven defects were confirmed on the ceramic green sheet.
C: 11 or more uneven defects were confirmed on the ceramic green sheet.

<Windability in high-speed conveyance (high-speed windability)>
A winding test at high speed transport was performed by winding up the release films produced in each of Examples and Comparative Examples under the following conditions.
The release film was transported at a line speed of 80 m / min and a tension of 7 kg / m, and pressed with a contact roll at a pressure of 30 kg / m, ABS (acrylonitrile-butadiene) having a diameter of 6 inches (1 inch = 2.54 cm). -Styrene) A release film having a length of 6,000 m in the longitudinal direction was wound into a roll by winding it around a winding core made of resin. The hardness of the contact roll was 60 degrees.
The rolled release film roll was visually observed, and from the observation results, the winding property during high-speed transportation was evaluated based on the following evaluation criteria.

(Windability evaluation criteria)
A: No winding misalignment was observed.
B: Winding misalignment was observed.

<Defect evaluation of ceramic layer when conveyed at high speed>
As the release film, the same method as described in Defect Evaluation 1 of Ceramic Green Sheet was used, except that a release film wound under high-speed transport conditions according to the method described in the method for evaluating winding properties at high-speed transport was used. A ceramic green sheet was provided on the release surface of the release film.
The obtained release film with ceramic green sheets was unwound and laminated on a glass substrate with electrodes so that the ceramic green sheets formed on the release film were in contact with the glass substrate. The resulting laminate was thermocompression bonded (100° C., 0.5 MPa) using a heating roller. After that, the release film was peeled off from the laminate, and the glass substrate to which the ceramic green sheet was pressure-bonded was fired at 400°C for 20 minutes. By firing for 30 minutes, a glass substrate having a ceramic layer formed on its surface was obtained.
An observation area (100 mm×100 mm) on the surface of the resulting ceramic layer was observed for the presence or absence of uneven defects using an optical microscope. Based on the confirmed number of defects in the observation area, defects in the fired ceramic layer were evaluated according to the following criteria. If there are few defects in the ceramic layer after firing as confirmed by the above evaluation method, even in a multilayer ceramic capacitor manufactured using ceramic green sheets formed on the release surface of the same release film, the characteristics as a capacitor are affected. Since it is possible to suppress the formation of minute irregularities that may occur, it is considered that the performance of suppressing the defect rate of the multilayer ceramic capacitor is superior.

(Evaluation criteria)
A: No defect was observed in the ceramic layer after firing.
B: 1 to 3 defects were observed in the ceramic layer after firing.
C: Four or more defects were observed in the ceramic layer after firing.

<Peelability evaluation>
Delamination with a ceramic green sheet was performed in the same manner as described in Defect evaluation 1 of the ceramic green sheet, except that the amount of ceramic slurry applied was adjusted so that the thickness of the ceramic green sheet (slurry coating film after drying) was 3 μm. got the film. A polyester adhesive tape No. 31B (manufactured by Nitto Denko Corporation) was attached to the surface of the ceramic green sheet in the release film with the ceramic green sheet. In this state, the film was allowed to stand at room temperature (25° C.) for 24 hours, and then the release film with the ceramic green sheet was cut into a width of 20 mm to prepare a sample. The adhesive tape side of the sample is fixed to the surface of the glass plate, and using a Tensilon universal tester manufactured by A&D Co., Ltd., under the conditions of a peeling angle of 180 ° and a peeling speed of 100 mm / min, the release film from the ceramic green sheet. was peeled off and the force required to peel off was measured.

Peelability was evaluated according to the following criteria.
(Evaluation criteria)
A: When peeling from the ceramic green sheet, it can be peeled off with a force of 45 mN or less.
B: When peeling from the ceramic green sheet, a force of more than 45 mN and 100 mN or less is required.
C: A force of more than 100 mN is required when peeling from the ceramic green sheet.

The composition and characteristics of the particle-containing layer and the release layer, and the evaluation results of the evaluation test described above are shown in Table 1 below for the release films produced in each example and each comparative example.

In Table 1, the descriptions in the "Particles" column and the "Binder" column indicate that the following components were used.
(particle)
・ O1: Crosslinked PMMA particles, Eposter (registered trademark) MX050W, manufactured by Nippon Shokubai Co., Ltd., average particle size 70 nm
・ O2: Crosslinked PMMA particles, Eposter (registered trademark) MX100W, manufactured by Nippon Shokubai Co., Ltd., average particle size 150 nm
・ O3: Crosslinked PMMA particles, Eposter (registered trademark) MX200W, manufactured by Nippon Shokubai Co., Ltd., average particle size 350 nm
・ O4: Crosslinked PMMA particles, Eposter (registered trademark) MX300W, manufactured by Nippon Shokubai Co., Ltd., average particle size 450 nm
・ O5: Non-crosslinked PMMA particles, Techpolymer (registered trademark) MB-4, manufactured by Sekisui Plastics Co., Ltd., average particle size 4.0 μm
・ I1: colloidal silica, Snowtex (registered trademark) MP-2040, manufactured by Nissan Chemical Industries, Ltd., average particle size 200 nm

(binder)
・Urethane resin 1: Hydran (registered trademark) AP-40N, manufactured by DIC Corporation ・Urethane resin 2: ADEKA BONDITTER (registered trademark) HUX-524, manufactured by ADEKA Corporation.
Olefin resin: Zaixen (registered trademark) NC, manufactured by Sumitomo Seika Co., Ltd.
Acrylic resin 1: a copolymer obtained by polymerizing methyl methacrylate, styrene, 2-ethylhexyl acrylate, 2-hydroxyethyl methacrylate and acrylic acid at a mass ratio of 59:8:26:5:2.
-Polyester resin: Polymerization of dimethyl terephthalate, dimethyl isophthalate, dimethyl-5-sodium sulfoisophthalate, ethylene glycol and neopentyl glycol at a mass ratio of 194.2:184.5:14.8:185.1:185.1 A copolymer formed by

In Table 1, the "thickness" column indicates the thickness of the particle-containing layer and the release layer, respectively. The method for measuring the thickness of each layer is as described above. After taking out the cross section of the release film with a microtome, etching treatment is performed with Ar ions, Pt is deposited, and SEM (S-4800, manufactured by Hitachi High Tech). was observed and measured.

In Table 1, the "Sp" column indicates the maximum protrusion height Sp of the particle-containing layer and the peeling layer, and the "Sa" column indicates the surface average roughness Sa of the peeling layer. The definitions of the “maximum protrusion height Sp” and the “surface average roughness Sa” of each layer are as described above, and the measurement method is also as described above. was measured using
In Table 1, the "Surface E" column shows the surface free energies of the conveying surface and the peeling surface. The definition and measurement method of the surface free energy of each layer are as described above. It was obtained from the results of dripping drops of methylene and ethylene glycol.

In Table 1, the column "ratio of organic particle protrusions" indicates the ratio (number ratio) of protrusions formed by organic particles among the protrusions present on the conveying surface. The method for measuring the proportion of protrusions formed by organic particles is as described above, and "P" indicates that the proportion of protrusions formed by organic particles is 50% or more among the protrusions present on the conveying surface. and "N" when the percentage of protrusions formed by organic particles is less than 50%.

In Table 1, the column "Sp Forming Particles" indicates whether or not the protrusions having the maximum protrusion height Sp among the protrusions present on the conveying surface are protrusions formed of organic particles. The analysis as to whether or not the particles forming the maximum protrusion height Sp among the protrusions on the conveying surface are organic particles was performed as follows.
Mark the transfer surface of the release film with a felt pen, and use an optical interferometer (Vertscan R3300G Lite, manufactured by Hitachi High-Tech Co., Ltd.) in the vicinity of the mark to measure the maximum protrusion height Sp under the following measurement conditions. bottom. In the measurement of the maximum protrusion height Sp, dust present on the conveying surface and coarsely aggregated particles of 1 μm or more were not counted.
(Measurement condition)
・Measurement mode: WAVE mode ・Objective lens: 50x ・Measurement area: 186 μm×155 μm
Next, the sample was deposited with platinum, and an image near the marks on the transfer surface was imaged at low magnification using an SEM (“S4700”, manufactured by Hitachi High-Tech Co., Ltd.) while tilted at 15° with respect to the horizontal plane. Among the projections present in the observation area (measurement field) of 100 μm × 100 μm, select the projections that match the maximum projection height Sp, analyze the element distribution with an EDS analyzer, and match the maximum projection height It was determined whether the particles forming the protrusions were organic particles or inorganic particles. The method for determining organic particles and inorganic particles is as described above.
In 10 different observation areas on the conveying surface of the sample, it was specified whether the particles forming the protrusions exhibiting the maximum protrusion height Sp were organic particles or inorganic particles. A case where the number ratio of the organic particles to the particles forming the protrusions exhibiting the maximum protrusion height Sp was 50% or more was rated as "O", and the others were rated as "I".
When the determination result by the above method is "O", the release film is evaluated as having a conveying surface on which protrusions having the maximum protrusion height Sp are formed by organic particles.

As shown in Table 1, when ceramic green sheets were produced using the release films of Examples 1 to 13 according to the present invention, compared to Comparative Example 1, the ceramic green sheets were fired even when conveyed at high speed. It was confirmed that the occurrence of defects on the surface of the obtained ceramic layer can be suppressed. From this result, when ceramic green sheets were produced using the release films of Examples 1 to 13, and when laminated ceramic capacitors were produced using the obtained ceramic green sheets, when the release film of Comparative Example 1 was used. It is thought that the manufacturing ratio of multilayer ceramic capacitors with low electrical characteristics will be low compared to

Further, as shown in Table 1, in the release films of Examples 1 to 13 according to the present invention, even when used for producing a ceramic green sheet after long-term storage, the particle-containing layer does not contain a non-polyester resin. It was confirmed that, compared with Comparative Example 2, the occurrence of defects in the produced ceramic green sheets can be suppressed.

In the release film, when the maximum protrusion height Sp on the surface of the particle-containing layer opposite to the polyester substrate is 25 nm or more, it was confirmed that the release film has excellent winding properties during high-speed transportation. It was confirmed that when the height Sp is 1000 nm or less, the ceramic green sheet has excellent defect suppression performance (comparison with Examples 1 to 13).

When the surface of the particle-containing layer opposite to the polyester substrate has projections, and the proportion of the projections formed by the organic particles is 50 to 100% of these projections, the ceramic layer can be transported at a high speed. It was confirmed that the surface defect suppression performance was superior (comparison with Examples 5 to 7).
If the surface of the particle-containing layer opposite to the polyester substrate has projections, and among these projections, the projections having the maximum projection height Sp are the projections formed by the organic particles, the high-speed transport is not possible. It was confirmed that the performance of suppressing defects on the surface of the ceramic layer is excellent (comparison with Examples 5-6 and 12-13).

It was confirmed that when the surface free energy of the surface of the release layer opposite to the polyester substrate is 30 mJ/m ² or less, the release property is excellent (compare Examples 1 and 10 to 11).
It was confirmed that when the surface free energy of the surface of the particle-containing layer opposite to the polyester base material is 45 mJ/m ² or less, the defect suppression performance of the ceramic green sheet is superior (comparison with Examples 1 to 4). .

1: Release film 2: Release layer 4: Polyester substrate 6: Particle-containing layer 21: Surface (release surface)
61: Surface (conveyance surface)

Claims

A release film comprising a release layer, a polyester base material, and a particle-containing layer in this order,
the particle-containing layer comprises particles and a non-polyester resin;
the particles comprise organic particles;
A release film, wherein the release layer contains a silicone compound.
The release film according to claim 1, which is used for manufacturing ceramic green sheets.
The release film according to claim 1 or 2, wherein the polyester base material is substantially free of particles.
The surface of the particle-containing layer opposite to the polyester base has projections,
3. The release film according to claim 1, wherein the number of protrusions formed by organic particles accounts for 50 to 100% of the protrusions.
The surface of the particle-containing layer opposite to the polyester base has projections,
The release film according to claim 1 or 2, wherein the protrusions having the maximum protrusion height Sp among the protrusions are protrusions formed of organic particles.
3. The surface free energy of the surface of the release layer opposite to the polyester substrate is 10 to 30 mJ/m 2 and the maximum protrusion height Sp is 1 to 30 nm, according to claim 1 or 2. release film.
The release film according to claim 1 or 2, wherein the organic particles contain at least one selected from the group consisting of styrene resins, urethane resins, acrylic resins, and divinylbenzene resins.
The surface free energy of the surface of the particle-containing layer opposite to the polyester substrate is 25 to 45 mJ/m 2 and the maximum projection height Sp is 25 to 1000 nm, according to claim 1 or 2 Release film as described.
The release film according to claim 1 or 2, wherein the non-polyester resin is at least one resin selected from the group consisting of acrylic resins, urethane resins, and olefin resins.
The release film according to claim 1 or 2, wherein the release film has a thickness of 40 µm or less.
The release film according to claim 1 or 2, wherein the particle-containing layer has a thickness of 1 to 500 nm.
A method for producing a release film according to claim 1 or 2,
A method for producing a release film, comprising the step of applying a particle-containing layer-forming composition containing organic particles and a non-polyester resin to one surface of a polyester substrate.
A ceramic capacitor manufactured using the release film according to claim 1 or 2.