JP2023151185A - Release film, method for producing release film, and laminate - Google Patents

Abstract

To provide a release film with excellent releasability and solvent resistance and application thereof.SOLUTION: A release film includes a polyester substrate and a release layer, wherein the release layer is formed by crosslinking compositions including a silicone compound and a carbodiimide compound and satisfies at least one of the following conditions 1 and 2. There are also provided applications thereof. Condition 1: the silicone compound includes an acid radical. Condition 2: the composition further includes at least one acid group-containing nonsilicone resin selected from the group consisting of an acid group-containing urethane resin and an acid group-containing olefin resin.SELECTED DRAWING: None

Description

The present disclosure relates to a release film, a method for manufacturing a release film, and a laminate.

BACKGROUND OF THE INVENTION As electronic devices become more sophisticated and smaller, electronic components used in electronic devices are also required to have higher performance and become smaller. Among electronic components, for example, the number of mounting points on a board is increasing for multilayer ceramic capacitors, and there is a strong demand for miniaturization.
In manufacturing multilayer ceramic capacitors, a common method is to apply a ceramic slurry onto a release film having a release layer and dry it to form a ceramic green sheet.

For example, Patent Document 1 discloses a release film including a polyester film and a release layer, the release layer having the release layer on at least one side of the polyester film directly or via another layer, the release layer comprising: A release film is described which is obtained by curing a composition containing an acrylic resin having a long-chain alkyl group and at least one crosslinking agent selected from an oxazoline crosslinking agent or a carbodiimide crosslinking agent. Patent Document 2 discloses that a polyester film has, on at least one side thereof, a coating layer formed from a coating liquid containing a crosslinking agent and a mold release agent, and further containing 30% by weight or less of polymers other than these as non-volatile components. A laminated polyester film is described. Patent Document 3 describes a laminated film having a resin layer on at least one side of a polyester film, the resin layer is on at least one surface layer, the water contact angle of the resin layer is 85° or more and 100° or less, and the laminated film is A laminated film is described where |H2-H1|≦1.0(%), where the haze of the laminated film is H1 (%) and the haze after subjecting the laminated film to a solvent immersion/scratching test is H2 (%). .

International Publication No. 2020/129962 JP 2016-30378 Publication International Publication No. 2020/017289

However, in release films, improvements in release properties and solvent resistance are sometimes required. In particular, when the release film is used to manufacture ceramic green sheets, there is still room for improvement in terms of peelability from the ceramic green sheet and improvement of solvent resistance when ceramic slurry is applied to the release film. there were.

The present disclosure has been made in view of the above circumstances, and an object to be solved by an embodiment of the present invention is to provide a release film with excellent peelability and solvent resistance, and a method for manufacturing the release film. In particular, it is an object of the present invention to provide a release film that has excellent releasability from a ceramic green sheet and excellent solvent resistance when coated with a ceramic slurry, and a method for producing the release film.
Another problem to be solved by other embodiments of the present invention is to provide a laminate including a release film that has excellent releasability and solvent resistance, and in particular, has excellent releasability from ceramic green sheets and An object of the present invention is to provide a laminate including a release film having excellent solvent resistance when coated with a ceramic slurry.

The present disclosure includes the following aspects.
<1> Contains a polyester base material and a release layer, the release layer is formed by crosslinking a composition containing a silicone compound and a carbodiimide compound, and satisfies at least one of the following conditions 1 and 2. , release film.
Condition 1: The silicone compound contains an acid group.
Condition 2: The composition further contains at least one acid group-containing non-silicone resin selected from the group consisting of acid group-containing urethane resins and acid group-containing olefin resins.
<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 does not substantially contain particles.
<4> The composition further contains an acid group-containing non-silicone resin, and the mass ratio of the content of the acid group-containing non-silicone resin to the content of the silicone compound in the composition is 1 to 30, <1 The release film according to any one of > to <3>.
<5> The release film according to any one of <1> to <4>, wherein the mass ratio of the silicone compound content to the carbodiimide compound content in the composition is 0.1 to 10.
<6> The release film according to any one of <1> to <5>, wherein the release layer has a thickness of 0.001 μm to 0.2 μm.
<7> The release film according to any one of <1> to <6>, further comprising a particle-containing layer, and comprising a release layer, a polyester base material, and a particle-containing layer in this order.
<8> The release film according to <7>, wherein the particle-containing layer contains a non-polyester resin.
<9> The release film according 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> A method for producing a release film comprising a polyester base material and a release layer,
A method for producing a release film, comprising the step of forming a release layer using a release layer forming composition containing a silicone compound and a carbodiimide compound.
<11> In <10>, the step of forming a release layer is a step of applying a release layer forming composition to one side of an unstretched polyester film or a uniaxially stretched polyester film to form a release layer. The method for producing the release film described above.
<12> A laminate comprising the release film according to any one of <1> to <9> and a layer containing ceramic.

According to an embodiment of the present invention, a release film having excellent peelability and solvent resistance, and a method for manufacturing the release film, particularly, peelability from a ceramic green sheet and solvent resistance when ceramic slurry is applied. Provided are a release film with excellent properties and a method for producing the release film.
Further, according to another embodiment of the present invention, a laminate including a release film having excellent peelability and solvent resistance, particularly peelability from a ceramic green sheet and solvent resistance when ceramic slurry is applied, is provided. A laminate including a release film having excellent properties is provided.

Hereinafter, the release film, the method for manufacturing the release film, and the laminate of the present disclosure will be described in detail.

In this specification, a numerical range indicated using "~" means a range that includes the numerical values listed before and after "~" as the minimum and maximum values, respectively.
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 value shown in the Examples.

In the present specification, if there are multiple substances corresponding to each component in the composition, unless otherwise specified, the amount of each component in the composition refers to the total amount of the multiple substances present in the composition. means.
In this specification, a combination of two or more preferred embodiments is a more preferred embodiment.
As used herein, the term "process" is used not only to refer to an independent process, but also to include a process that is not clearly distinguishable from other processes, as long as the intended purpose of the process is achieved. It will be done.

As used herein, the term "longitudinal direction" refers to the longitudinal direction of the release film during production, and has the same meaning as the "conveyance direction" and the "machine direction".
In this specification, "width direction" means a direction perpendicular to the longitudinal direction. In this specification, "orthogonal" is not limited to strictly orthogonal, but includes substantially orthogonal. "Substantially perpendicular" means that they intersect within a range of 90°±5°, preferably within a range of 90°±3°, and more preferably within a range of 90°±1°. .
Further, 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 disclosure includes a polyester base material and a release layer, the release layer is formed by crosslinking a composition containing a silicone compound and a carbodiimide compound, and satisfies the conditions 1 and 2 below. satisfies at least one of the
Condition 1: The silicone compound contains an acid group.
Condition 2: The composition further contains at least one acid group-containing non-silicone resin selected from the group consisting of acid group-containing urethane resins and acid group-containing olefin resins.

The release film of the present disclosure has excellent release properties and solvent resistance. Although the reason for this is not certain, it is assumed as follows.

In the release film of the present disclosure, the release layer is formed by crosslinking a composition containing a silicone compound and a carbodiimide compound. The release layer is obtained by crosslinking the carbodiimide compound with the components contained in the composition. The component that crosslinks with the carbodiimide compound may be a silicone compound or a component other than a silicone compound. In the release layer, when the silicone compound contains an acid group, it is thought that the carbodiimide compound reacts with the silicone compound containing the acid group and is crosslinked. Further, when the above composition contains at least one acid group-containing non-silicone resin selected from the group consisting of acid group-containing urethane resins and acid group-containing olefin resins, the carbodiimide compound is combined with this non-silicone resin. It is thought to be crosslinked. Since the release layer contains a crosslinked product based on a carbodiimide compound, it has excellent solvent resistance. Since the release layer contains a silicone compound and a crosslinked product having a structure derived from the silicone compound, it has excellent releasability. In addition, the silicone compound contained in the composition for forming a release layer is unevenly distributed on the surface layer to make the surface hydrophobic, and the non-silicone resin crosslinks with the carbodiimide compound inside the release layer, resulting in better release properties and solvent resistance. considered to be a thing.

On the other hand, Patent Document 1 and Patent Document 3 have no description regarding silicone compounds containing acid groups, urethane resins containing acid groups, and olefin resins containing acid groups. Patent Document 2 does not include any description focusing on silicone compounds.

<Polyester base material>
A polyester substrate is a film-like object that contains polyester resin as the main polymer component. Here, the term "main polymer component" means a polymer having the highest content (mass) of all polymers contained in the film-like object.
The polyester base material may contain one type of polyester resin alone, or may contain two or more types of polyester resin.

[Polyester resin]
Polyester resin is a polymer having ester bonds 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.
In the present disclosure, the term "main chain" refers to the relatively longest bonding chain in the molecules of the polymer compound constituting the resin.
The polyester resin is not particularly limited, and any known polyester resin can be used. Examples of the polyester resin include polyethylene terephthalate (PET), polyethylene-2,6-naphthalate (PEN), polypropylene terephthalate (PPT), polybutylene terephthalate (PBT), and copolymers thereof, among which, 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°C to 270°C, more preferably 245°C to 265°C.
The glass transition temperature (Tg) of the polyester resin is preferably 65°C to 90°C, more preferably 70°C to 85°C.

The method for producing polyester resin is not particularly limited, and any known method 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.
Hereinafter, materials used for manufacturing polyester and manufacturing conditions will be explained.

(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. Examples include esters. Among these, aromatic dicarboxylic acid or methyl aromatic dicarboxylate is preferred.

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.
Examples of the alicyclic dicarboxylic acid compound include adamantane dicarboxylic acid, norbornene dicarboxylic acid, cyclohexane dicarboxylic acid, and decalin dicarboxylic acid.

Examples of aromatic dicarboxylic acid compounds include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalene dicarboxylic acid, 1,5-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, and 1,8-naphthalene dicarboxylic acid. , 4,4'-diphenyl dicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 5-sodium sulfoisophthalic acid, phenylindane dicarboxylic acid, anthracene dicarboxylic acid, phenanthrene dicarboxylic acid, and 9,9'-bis(4- (carboxyphenyl)fluorenic acid and methyl esters thereof.
Among these, terephthalic acid or 2,6-naphthalene dicarboxylic acid is preferred, and terephthalic acid is more preferred.

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 other aromatic dicarboxylic acids such as isophthalic acid or aliphatic dicarboxylic acids.

(Diol compound)
Examples of the diol compound 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 Mention may be made of pentyl glycol, with ethylene glycol being preferred.
Examples of the alicyclic diol compound include cyclohexanedimethanol, spiroglycol, and isosorbide.
Examples of the aromatic diol compound include bisphenol A, 1,3-benzenedimethanol, 1,4-benzenedimethanol, and 9,9'-bis(4-hydroxyphenyl)fluorene.
One type of diol compound may be used, or two or more types may be used in combination.

(catalyst)
The catalyst used for producing polyester resin is not particularly limited, and any known catalyst that can be used for synthesizing polyester resin can be used.
Examples of the catalyst 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 these, titanium compounds are preferred from the viewpoints of catalytic activity and cost.
One type of catalyst may be used, or two or more types 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; and phosphorus. It is preferable to use a titanium compound and a phosphorus 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.
Examples of organic acids include citric acid, lactic acid, trimellitic acid, and malic acid.
As the titanium compound, the titanium compounds described in [0049] to [0053] of Japanese Patent No. 5,575,671 can also be used, and the contents of the above publication are incorporated into the present specification.

(terminal sealant)
In the production of polyester resin, a terminal capping agent may be used as necessary. By using the terminal capping agent, a structure derived from the terminal capping agent is introduced at the end of the polyester resin.
The terminal capping agent is not limited, and any known terminal capping agent can be used. Examples of the terminal capping agent include oxazoline compounds, carbodiimide compounds, and epoxy compounds.
As for the terminal capping agent, the contents described in [0055] to [0064] of JP-A No. 2014-189002 can also be referred to, and the contents of the above publication are incorporated into the present specification.

(manufacturing conditions)
The reaction temperature when producing the polyester resin is not limited and may be appropriately set depending on the raw materials. The reaction temperature is preferably 260°C to 300°C, more preferably 275°C to 285°C.
The pressure when producing the polyester resin is not limited, and may be appropriately set depending on 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 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 into the present specification.

[Content of each component]
The content of the polyester resin in the polyester base material is preferably 85% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and 98% by mass based on the total mass of the polymer in the polyester base material. % 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 based on 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. It is preferably 98 to 100% by weight, more preferably 98% to 100% by weight, and particularly preferably 100% by weight.

The polyester base material may contain components other than the polyester resin (for example, a 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 included in a particle-containing layer described below.
"Substantially free of particles" means that when a polyester base material is quantitatively analyzed for elements derived from particles by fluorescent X-ray analysis, the content of particles is 50% by mass based on the total mass of the polyester base material. It is defined as not more than ppm, preferably not more than 10 mass ppm, more preferably not more than the detection limit. This is because even if particles are not actively added to the polyester base material, contaminants derived from foreign substances, raw resin, or dirt attached to the line or equipment in the polyester base material manufacturing process are peeled off and the polyester base material This is because it 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 biaxial directions. 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 axes is preferably within the range of 90°±5°, more preferably within the range of 90°±3°, and even more preferably within the range of 90°±1°. The biaxially oriented polyester base material in the release film of the present disclosure preferably has molecular orientation in the longitudinal direction and the width direction. The biaxially oriented polyester base material can be manufactured by the method described below.

(density)
The density of the polyester base material is preferably 1.39g/cm ³ to 1.41g/cm ³ , more preferably 1.395g/cm ³ to 1.405g/cm ³ , and 1.398g/cm ³ to 1.400g /cm ³ is more preferable.
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 standpoint of controlling releasability. The lower limit of the thickness is not particularly limited, but from the viewpoint of improving strength and workability, it is preferably 3 μm or more, more preferably 10 μm or more, and even more preferably 20 μm or more.
The thickness of the polyester base material can be determined by preparing a section with a cross section perpendicular to the main surface of the release film and using a scanning electron microscope (SEM) or transmission electron microscope (TEM). This is the arithmetic mean value of the thicknesses of the above section measured at five locations.

<Peeling layer>
The release layer is provided to enable the release film to be peeled off. When a release film is used to produce a ceramic green sheet, the ceramic green sheet is formed on the release surface of the release layer, which is the surface opposite to the polyester substrate. That is, the ceramic green sheet is releasably provided on the release surface of the release film.
Note that 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, but it is preferable to provide the release layer directly on the surface of the polyester base material because it has better smoothness. It is preferable to provide one.

The release layer is formed by crosslinking a composition containing a silicone compound and a carbodiimide compound. Hereinafter, a composition containing a silicone compound and a carbodiimide compound will also be referred to as a "composition for forming a release layer."

[Silicone compound]
The release layer forming composition contains a silicone compound. When a silicone compound is contained, the release layer has excellent releasability.

The silicone compound is not particularly limited as long as it has a siloxane bond in its molecule. The silicone compound is preferably a compound having a dimethylsiloxane structure in terms of superior releasability. The silicone compound may be a low molecular weight compound, an oligomer, or a resin, but is preferably an oligomer or a resin.

The weight average molecular weight of the silicone compound is preferably 150 or more, more preferably 350 or more, and even more preferably 650 or more. The upper limit of the weight average molecular weight is not particularly limited, and is, for example, 1 million. The weight average molecular weight of the silicone compound is preferably 100,000 or less, more preferably 10,000 or less.

In this disclosure, weight average molecular weight (Mw) means a value measured by gel permeation chromatography (GPC). In addition, when the molecular weight is 1000 or less, the molecular weight is calculated based on the type and number of atoms constituting the compound.

For measurement by GPC, HLC (registered trademark)-8020GPC (Tosoh Corporation) was used as the measuring device, and TSKgel (registered trademark) Super Multipore HZ-H (4.6 mm ID x 15 cm, Tosoh Corporation) was used as the column. Using three bottles, THF (tetrahydrofuran) is used as the eluent. The measurement conditions are as follows: sample concentration is 0.45% by mass, flow rate is 0.35ml/min, sample injection amount is 10 μL, and measurement temperature is 40° C., using an RI detector.
The calibration curve is based on Tosoh Corporation's "Standard Sample TSK standard, polystyrene": "F-40", "F-20", "F-4", "F-1", "A-5000", "A -2500'', ``A-1000'', and 8 samples of ``n-propylbenzene''.

As the silicone compound, a crosslinkable silicone compound is preferred since it has better solvent resistance. The component crosslinked by the silicone compound may be a carbodiimide compound or another component included in the release layer, and the crosslinkable site is introduced into at least one of the terminal and side chain of the silicone compound. It is preferable.

Examples of the silicone compound include polydimethylsiloxane and hydrogen siloxane in which a vinyl group is introduced into at least one of the terminal and side chain. These silicone compounds have excellent solvent resistance because a crosslinked product can be obtained by reacting them using a platinum catalyst.
Examples of the silicone compound include polydimethylsiloxane having a hydroxyl group at the end and polydimethylsiloxane having a hydrogen atom at the end. These silicone compounds have excellent solvent resistance because a crosslinked product is obtained by a condensation reaction using an organotin catalyst.
Further, the silicone compound may be a silicone compound that can be crosslinked by the action of ultraviolet rays or electron beams. Examples of silicone compounds that can be crosslinked by the action of ultraviolet rays or electron beams include radically polymerizable silicone compounds and silicone compounds having epoxy groups. More specifically, acrylate-modified polydimethylsiloxane, and glycidoxy-modified polydimethylsiloxane.

Among these, the silicone compound preferably contains an acid group from the viewpoint of crosslinkability with the carbodiimide compound, and more preferably contains an acid group in at least one of the terminal and side chain of the silicone compound. When the silicone compound contains an acid group, the hydrophobic surface is cured by crosslinking, thereby further improving solvent resistance.

Examples of the acid group include a carboxy group, a sulfo group, a phosphonic acid group, and a phosphoric acid group. Among these, from the viewpoint of crosslinkability with the carbodiimide compound, the acid group is preferably a carboxy group. That is, it is preferable that the silicone compound has a carboxy group.

The composition for forming a release layer may contain only one type of silicone compound, or may contain two or more types of silicone compounds.
In the composition for forming a release layer, the silicone compound is preferably a silicone compound containing an acid group, and a silicone compound containing an acid group and a silicone compound not containing an acid group may be used in combination.

The content of the silicone compound is preferably 1% by mass to 90% by mass, based on the total solid content of the composition for forming a release layer, and 5% by mass to 76% by mass in terms of superior peelability and solvent resistance. It is more preferable that it is mass %. In addition, in this disclosure, the solid content means the total mass excluding liquid components such as water and solvent contained in the composition for forming a release layer.

[Carbodiimide compound]
The release layer forming composition contains a carbodiimide compound. When the carbodiimide compound is contained, the release layer has excellent solvent resistance.

Since the carbodiimide compound has a function as a crosslinking agent, it is considered that by including a crosslinked product based on the carbodiimide compound in the release layer, the release layer becomes more hydrophobic and has excellent solvent resistance. In addition, since the crosslinked product based on a carbodiimide compound has excellent flexibility, for example, when a stretching process is performed after applying a composition for forming a release layer on a polyester film, which will be described later, the composition for forming a release layer can be applied. Since the film formed by the method is also stretched, minute defects such as cracks are less likely to occur in the release layer. As a result, it is thought that even when applied to the production of ceramic green sheets, minute unevenness defects can be suppressed.

Carbodiimide compounds can be synthesized by conventionally known methods. For example, a condensation reaction of diisoanate compounds is used. The diisocyanate compound is not particularly limited, and may be any of aromatic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates.

Examples of aromatic diisocyanates include 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyl diisocyanate, tetraalkyldiphenylmethane diisocyanate, and dialkyldiphenylmethane. Diisocyanate, 1,3-phenylene diisocyanate, polymeric diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, 4,4' diphenyl ether diisocyanate, 1,5-naphthylene diisocyanate Isocyanates and naphthalene diisocyanates are mentioned.

Examples of aliphatic diisocyanates include hexamethylene diisocyanate, trimethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, xylylene diisocyanate, and 1,2-propylene. Examples include diisocyanate, butylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, and 1,5-pentamethylene diisocyanate.

Examples of the alicyclic diisocyanate include 1,3-cyclopentane diisocyanate, 1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, 3-isocyanate methyl-3,5,5-trimethyl Examples include cyclohexyl isocyanate, 2,4-methylcyclohexane diisocyanate, 2,6-methylcyclohexane diisocyanate, and norbornane diisocyanate.

The carbodiimide equivalent (mass [g] of the carbodiimide compound to provide 1 mole of carbodiimide group) is preferably 100 g/mol to 1000 g/mol, more preferably 250 g/mol to 800 g/mol, and 300 g/mol. More preferably, it is from mol to 700 g/mol.

The composition for forming a release layer may contain only one type of carbodiimide compound, or may contain two or more types of carbodiimide compounds.

The content of the carbodiimide compound is preferably 1% by mass or more, based on the total solid content of the composition for forming a release layer, and more preferably 9% by mass or more in terms of better solvent resistance. The upper limit of the content of the carbodiimide compound is, for example, 80% by mass or less. In terms of superior peelability, the content of the carbodiimide compound is preferably less than 29% by mass, more preferably 28% by mass or less.

In the composition for forming a release layer, the mass ratio of the content of the silicone compound to the content of the carbodiimide compound is preferably 0.05 to 10, and is 0.1 to 10 in terms of superior release properties and solvent resistance. It is more preferably 0.3 to 6. When the mass ratio is 0.1 or more, releasability is improved. On the other hand, when the mass ratio is 10 or less, solvent resistance is improved.

[Acid group-containing non-silicone resin]
It is preferable that the composition for forming a release layer further contains at least one acid group-containing non-silicone resin selected from the group consisting of acid group-containing urethane resins and acid group-containing olefin resins. Acid group-containing non-silicone resin means a non-silicone resin containing acid groups.
When the acid group-containing non-silicone resin is contained, the crosslinking density increases and the solvent resistance is further improved. In addition, the silicone compound contained in the composition for forming a release layer is unevenly distributed on the surface layer to make the surface hydrophobic, and the non-silicone resin crosslinks with the carbodiimide compound inside the release layer, resulting in better release properties and solvent resistance. considered to be a thing.

Examples of the acid group include a carboxy group, a sulfo group, a phosphonic acid group, and a phosphoric acid group. Among these, from the viewpoint of crosslinkability with the carbodiimide compound, the acid group is preferably a carboxy group.

The urethane resin is not limited as long as it is a polymer having a urethane bond in its main chain, and any known urethane resin such as a reaction product of a polyisocyanate compound and a polyol compound can be used.
Commercially available acid group-containing urethane resins include, for example, Hydran (registered trademark) AP-20, AP-40N, and AP-201 (manufactured by DIC), Takelac (registered trademark) W-605, W-5030, and W-5920 (manufactured by Mitsui Chemicals), Superflex (registered trademark) 210 and 130, and Elastron (registered trademark) H-3-DF, E-37 and H-15 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) (manufactured by).

The olefin resin may be any resin containing a structural unit derived from an olefin in its main chain.
The olefin is not particularly limited, but alkenes having 2 to 6 carbon atoms are preferred, ethylene, propylene, or hexene are more preferred, and ethylene is even more preferred.
The olefin-derived structural units of the polyolefin are preferably 50 mol% to 99 mol%, more preferably 60 mol% to 98 mol%, based on all the structural units of the polyolefin.

Examples of the acid group-containing olefin resin include copolymers obtained by modifying the above olefin resin with an acid-modifying component such as an unsaturated carboxylic acid or its anhydride.

Commercially available acid group-containing olefin resins include, for example, Zaixen (registered trademark) series such as Zaixen AC, A, L, NC, and N (manufactured by Sumitomo Seika Co., Ltd.), Chemipearl S100, S120, S200, S300, Chemipearl (registered trademark) series such as S650 and SA100 (manufactured by Mitsui Chemicals, Ltd.), Hitech (registered trademark) series such as Hitech S3121 and S3148K (manufactured by Toho Chemical Co., Ltd.), Arrowbase SE-1013, SE-1010 , SB-1200, SD-1200, SD-1200, DA-1010 and DB-4010, Arrowbase (registered trademark) series (manufactured by Unitika Co., Ltd.), Hardren AP-2, NZ-1004 and NZ-1005 ( (manufactured by Toyobo Co., Ltd.), as well as Sepolsion G315 and VA407 (manufactured by Sumitomo Seika Co., Ltd.).
Furthermore, acid-modified olefin resins described in [0022] to [0034] of JP-A No. 2014-076632 can also be preferably used.

Note that, as described above, the silicone compound contained in the composition for forming a release layer may be a silicone compound containing an acid group.

In the release film of the present disclosure, the release layer satisfies at least one of Condition 1 and Condition 2 below.
Condition 1: The silicone compound contains an acid group.
Condition 2: The release layer forming composition further contains at least one acid group-containing non-silicone resin selected from the group consisting of acid group-containing urethane resins and acid group-containing olefin resins.

The composition for forming a release layer may contain only one type of acid group-containing non-silicone resin, or may contain two or more types.

The content of the acid group-containing non-silicone resin in the composition for forming a release layer is preferably 0% by mass to 80% by mass based on the total solid content of the composition for forming a release layer. The content is more preferably 15% by mass to 68% by mass in terms of better solvent properties.

In the composition for forming a release layer, the mass ratio of the content of the acid group-containing non-silicone resin to the content of the silicone compound is preferably 0.1 to 50, since it has better release properties and solvent resistance. More preferably, it is 1 to 30. When the mass ratio is 1 or more, solvent resistance is improved. On the other hand, when the mass ratio is 30 or less, releasability is improved.

[Additive]
The release layer may contain additives in addition to the above components. As additives, additives such as surfactants, light release additives and heavy release additives for adjusting release force, adhesion improvers, and antistatic agents may be added.
As the surfactant, the same surfactant as that applied to the particle-containing layer can be used. Preferred embodiments of the surfactant that may be included in the release layer are the same as preferred embodiments of the surfactant that may be included in the particle-containing layer.

The composition for forming a release layer contains a hydrophilic monomer such as a polyalkylene oxide, a quaternary ammonium salt of dialkylamino alcohol, or a hydroxyalkyl sulfonate in order to improve the water solubility or water dispersibility of the carbodiimide compound. Good too. The composition for forming a release layer may contain a crosslinking catalyst for promoting crosslinking reaction by the carbodiimide compound.
Furthermore, the composition for forming a release layer may contain a crosslinking agent other than the carbodiimide compound.
Other crosslinking agents are not particularly limited, and known crosslinking agents can be used.
Examples of other crosslinking agents include melamine compounds, oxazoline compounds, epoxy compounds, and isocyanate compounds.
For details on the melamine compound, epoxy compound, and isocyanate compound, the descriptions in [0081] to [0083] of JP 2015-163457A can be referred to. The crosslinking agents described in [0082] to [0084] of International Publication No. 2017/169844 can also be preferably used.
For oxazoline compounds and isocyanate compounds, crosslinking agents described in [0074] to [0075] of International Publication No. 2018/034294 can also be preferably used.

When a carbodiimide compound and another crosslinking agent are used together, the other crosslinking agent is preferably an oxazoline compound.

When the composition for forming a release layer contains another crosslinking agent, the content of the other crosslinking agent is preferably 0.1% by mass to 20% by mass based on the total solid content of the composition for forming a release layer.

[Properties of release layer]
(thickness)
The thickness of the release layer may be set according to its purpose of use and is not particularly limited, but it is preferably 0.001 μm to 0.2 μm, and 0.01 μm in terms of well-balanced release performance and smoothness of the release surface. 0.2 μm is more preferable, and 0.03 μm to 0.1 μm is even more preferable.
The thickness of the release layer can be determined by preparing a section with a cross section perpendicular to the main surface of the release film and using a scanning electron microscope (SEM) or transmission electron microscope (TEM). The arithmetic mean value of the thicknesses measured at five locations on the section is taken as the arithmetic mean value.

<Particle-containing layer>
The release film of the present disclosure preferably further includes a particle-containing layer, and more preferably includes a release layer, a polyester base material, and a particle-containing layer in this order.

The particle-containing layer refers to a layer containing particles.
When the release film is provided with a particle-containing layer, the transportability of the release film can be improved. Specifically, it is possible to improve the winding quality (suppress blocking), suppress the occurrence of scratches and defects during transportation, and reduce transportation wrinkles during high-speed transportation.

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, but it is preferable to provide the particle-containing layer directly on the surface of the polyester base material because it has better adhesion. It is preferable to provide one.

Further, the particle-containing layer preferably contains particles and a binder, and may further contain additives.

The particles, binder, and additives will be explained below.

(particle)
The average particle diameter of the particles contained in the particle-containing layer is not particularly limited, and is preferably 10 nm to 2 μm, more preferably 30 nm to 1.5 μm, and 30 nm to 1.5 μm in terms of better transportability and suppressing transfer marks. 500 nm is more preferred.
In addition, in terms of better transportability and the ability to suppress transfer marks, the average particle diameter of the particles contained in the particle-containing layer is 10 nm to 200 nm (more preferably 30 nm to 130 nm), and the thickness of the particle-containing layer is 1 nm. ~200 nm (more preferably 10 nm ~ 100 nm), and the average particle diameter of the particles is preferably larger than the thickness of the particle-containing layer.

As the particles contained in the particle-containing layer, one type of particles may be used alone, or two or more types of particles may be used.
When the particle-containing layer contains two or more types of particles with different particle sizes, it is preferable that the particle-containing layer contains at least one type of particles with an average particle size within the above range, and two or more types of particles with different particle sizes. It is more preferable that all particles have an average particle diameter within the above range.

Examples of the particles contained in the particle-containing layer include organic particles and inorganic particles. Among these, organic particles are preferred from the viewpoint of suppressing the defective rate of ceramic capacitors manufactured using the obtained ceramic green sheets when the ceramic green sheets are manufactured.
As the organic particles, resin particles are preferred. Examples of the resin constituting the resin particles include acrylic resins such as polymethyl methacrylate resin (PMMA), polyester resins, silicone resins, styrene resins, and styrene-acrylic resins. The resin particles may have a crosslinked structure. Examples of resin particles having a crosslinked structure include divinylbenzene crosslinked particles.
Note that in the present disclosure, acrylic resin means a resin containing a structural unit derived from acrylate or methacrylate.
Examples of the inorganic particles include silica particles (silicon dioxide particles), titania particles (titanium oxide particles), calcium carbonate, barium sulfate, and alumina particles (aluminum oxide particles). Among these, the inorganic particles are preferably silica particles from the viewpoint of further improving haze and durability.

The shape of the particles is not particularly limited, and includes, for example, rice grain shape, spherical shape, cube shape, spindle shape, scale shape, aggregate shape, and irregular shape. Agglomerated state 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.

As the agglomerated particles, fumed silica particles are preferred. Examples of commercially available products include the Aerosil series manufactured by Nippon Aerosil Co., Ltd.
Colloidal silica particles are preferred as non-agglomerated particles. Examples of commercially available products include the Snowtex series manufactured by Nissan Chemical Co., Ltd.

The content of particles in the particle-containing layer is preferably 0.1% to 30% by mass, and preferably 1% to 25% by mass, based on the total mass of the particle-containing layer, from the viewpoint of transportability and suppressing transfer marks. The amount is more preferably 1% by weight to 15% by weight.
Further, the content of particles is preferably 0.0001% by mass to 0.01% by mass, more preferably 0.0005% by mass to 0.005% by mass, based on the total mass of the release film.

(Non-polyester resin (binder))
Preferably, the particle-containing layer contains a non-polyester resin. The non-polyester resin contained in the particle-containing layer has a function as a binder.

Non-polyester resin means resin other than polyester resin. Specifically, the non-polyester resin is preferably at least one selected from the group consisting of acrylic resin, urethane resin, olefin resin, polyvinyl alcohol resin, styrene butadiene resin, and acrylonitrile butadiene resin, and the non-polyester resin of the present disclosure In view of superior effects, it is preferable to use at least one resin selected from the group consisting of acrylic resins, urethane resins, and olefin resins.

Here, non-polyester resins (especially acrylic resins, urethane resins, and olefin resins) and polyester resins have different solubility parameters (SP values). In other words, since the compatibility of the acrylic resin, urethane resin, and olefin resin with the polyester resin is insufficient, impurities such as oligomers are difficult to precipitate from the polyester base material via the particle-containing layer onto the conveying surface. It is presumed that this makes it difficult for protrusions caused by impurities contained in the polyester base material to form on the conveying surface.

The above-mentioned 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 is preferably an acid group-containing non-polyester resin.
Moreover, the particle-containing layer may contain 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. The acrylic resin is not particularly limited, but preferably contains a structural unit derived from a (meth)acrylate having an alkyl group having 1 to 12 carbon atoms; It is more preferable to include a structural unit derived from the above.
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. Further, (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 from the viewpoint of application as an aqueous dispersion, it is preferably 2 mgKOH/g or more. By setting the acid value of the acrylic resin within the above range and/or by including a structural unit derived from a (meth)acrylate having an alkyl group having 1 to 12 carbon atoms, the resin becomes even more difficult to be compatible with the polyester resin. This can further suppress impurities such as oligomers contained in the polyester base material from precipitating 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, the resin can be made difficult to be compatible with polyester resin, and impurities such as oligomers contained in the polyester base material are suppressed from precipitating in the particle-containing layer. Defects in ceramic green sheets can be suppressed.
The olefin is not particularly limited, but alkenes having 2 to 6 carbon atoms are preferred, ethylene, propylene, or hexene are more preferred, and ethylene is even more preferred.
The olefin-derived structural units of the polyolefin are preferably 50 mol% to 99 mol%, more preferably 60 mol% to 98 mol%, based on all the structural units of the polyolefin.

As the olefin resin, acid group-containing olefin resins are preferred. Examples of the acid group-containing olefin resin include those similar to the acid group-containing olefin resin that may be included in the composition for forming a release layer.

The urethane resin is not limited as long as it is a polymer having a urethane bond in its main chain, and any known urethane resin such as a reaction product of a polyisocyanate compound and a polyol compound can be used.
The urethane resin is preferably an acid group-containing urethane resin, or a form containing a urethane resin and a dispersant, since it is easy to form a film by coating. Specific examples of the acid group are as described above.
For example, urethane resin can be made into a resin that is difficult to be miscible with polyester resin by adjusting the structure and hydrophobicity (hydrophilicity) of the polyol compound and isocyanate compound that are raw materials. The precipitation of impurities such as oligomers in the particle-containing layer is suppressed, and defects in the ceramic green sheet can be suppressed. It is preferable that the urethane resin contains a polyester structure, since defect suppression can be further improved.
Examples of the acid group-containing urethane resin include those similar to the acid group-containing urethane resin that may be included in the composition for forming a release layer.

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 composition for forming a particle-containing layer containing a crosslinking agent may be mentioned, as described below.

The particle-containing layer may contain one type of binder alone, or may contain two or more types of binders. Further, the particle-containing layer may contain one type of non-polyester resin, or may contain two or more types of non-polyester resin.
From the viewpoint of suppressing defects, the content of the binder (preferably non-polyester resin) is preferably 30% by mass to 99.8% by mass, and 50% by mass to 99.5% by mass, based on the total mass of the particle-containing layer. % is more preferable.

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

The particle-containing layer preferably contains a surfactant, since the smoothness of areas other than the areas where protrusions formed by particles are present on the conveying surface is improved.
The surfactant is not particularly limited, and includes silicone surfactants, fluorine surfactants, and hydrocarbon surfactants. Among these, the surfactant is preferably a hydrocarbon surfactant.

The silicone 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.
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), as well as KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF-642, Examples include KF-643, KF-6020, X-22-4515, KF-6011, KF-6012, KF-6015, and KF-6017 (all manufactured by Shin-Etsu Chemical Co., Ltd.).

The fluorine-based surfactant 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 (all of which are 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.) is mentioned.
In addition, from the viewpoint of improving environmental suitability, fluorine-based surfactants have a linear perfluoroalkyl group with a carbon number of 7 or more, such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). Preference is given to using surfactants derived from alternative materials of compounds.

Examples of the hydrocarbon surfactant include anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants.
Examples of anionic surfactants include alkyl sulfates, alkylbenzenesulfonates, alkyl phosphates, and fatty acid salts.
Examples of the nonionic surfactant include polyalkylene glycol mono- or dialkyl ether, polyalkylene glycol mono- or dialkyl ester, and polyalkylene glycol mono- or dialkyl ester/monoalkyl ether.
Examples of the cationic surfactant include primary to tertiary alkylamine salts and quaternary ammonium compounds.
Examples of amphoteric surfactants include surfactants having both an anionic site and a cationic site in the molecule.

Commercially available anionic surfactants include, for example, Rapizol (registered trademark) A-90, A-80, BW-30, B-90, and C-70 (all manufactured by NOF Corporation); NIKKOL (registered trademark) OTP-100 (manufactured by Nikko Chemical Co., Ltd.), Kohakuol (registered trademark) ON, L-40, and Phosphanol (registered trademark) 702 (manufactured by Toho Chemical Co., Ltd.) ), Viewlite (registered trademark) A-5000, and SSS (manufactured by Sanyo Chemical Industries, Ltd.).
Commercially available nonionic surfactants include, for example, Naroacty (registered trademark) CL-95 and HN-100 (trade name: manufactured by Sanyo Chemical Industries, Ltd.), Resolex BW400 (trade name: Kyukyu Alcohol Industry Co., Ltd.) Co., Ltd.), EMALEX (registered trademark) ET-2020 (manufactured by Nippon Emulsion Co., Ltd.), Surfynol (registered trademark) 104E, 420, 440, 465, and Dynor (registered trademark) 604, 607 (manufactured by Nissin Chemical Industry Co., Ltd.).

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

The anionic hydrocarbon surfactant preferably has a plurality of hydrophobic end groups in order to further improve smoothness. The hydrophobic terminal group may be a part of the hydrocarbon group that the hydrocarbon surfactant has. For example, a hydrocarbon surfactant having a branched hydrocarbon group at its end has a plurality of hydrophobic end groups.
Examples of anionic hydrocarbon surfactants having multiple hydrophobic end groups include di-2-ethylhexyl sodium sulfosuccinate (having four hydrophobic end groups) and di-2-ethyl octyl sodium sulfosuccinate (having four hydrophobic end groups). (having four hydrophobic end groups) and branched alkylbenzene sulfonates (having two 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% by mass to 10% by mass based on the total mass of the particle-containing layer. The amount is more preferably .1% to 5% by weight, and even more preferably 0.5% to 2% by weight.

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

[Properties of particle-containing layer]
(thickness)
For example, when the particle-containing layer is formed by applying a composition containing particles and a non-polyester resin onto one side of a polyester film, the thickness of the particle-containing layer is often 1 μm or less.
Further, when a polyester film having a laminated particle-containing layer is formed by coextrusion molding, the thickness of the particle-containing layer is often 1 μm to 10 μm.
The thickness of the particle-containing layer is preferably 1 nm to 3 μm, and when manufactured by coating, from the viewpoint of manufacturing suitability and haze reduction, the thickness is preferably 1 nm to 500 nm, more preferably 1 nm to 250 nm, even more preferably 10 nm to 100 nm, Particularly preferred is 20 nm to 100 nm.
The thickness of the particle-containing layer is determined by preparing a section having a cross section perpendicular to the main surface of the release film, and measuring the thickness of the section using a scanning electron microscope (SEM) or a transmission electron microscope (TEM). The arithmetic mean value of the thickness at five locations.

<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. Further, 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, from the viewpoint of improving strength and processability.
The thickness of the release film was measured using a continuous stylus film thickness meter. Specifically, it is carried out at five different locations. The arithmetic mean value of the obtained measured values is taken as the thickness.

[Manufacturing method of release film]
A method for manufacturing a release film of the present disclosure will be described.
The method for producing the release film of the present disclosure is not particularly limited as long as the above-mentioned release film can be obtained, and known methods may be used.

For example, the method for producing a release film of the present disclosure is a method for producing a release film including a polyester base material and a release layer, using a composition for forming a release layer containing a silicone compound and a carbodiimide compound. The method includes a step of forming a release layer.

Among these, the preferred method for producing a release film is as follows, since the release film can be produced with high productivity.
an extrusion molding step of forming an unstretched polyester film by extrusion molding;
A first stretching step of stretching an unstretched polyester film in either one of the transport direction and the width direction to form a uniaxially stretched polyester film, and a uniaxially stretched polyester film in the other of the transport direction and the width direction. a stretching step in which a second stretching step is carried out stepwise or simultaneously to form a biaxially stretched polyester film;
Between the extrusion molding step and the stretching step, between the first stretching step and the second stretching step, or after the stretching step, a release layer forming composition is applied to one surface of the polyester film to form a release layer. The manufacturing method includes a step of forming a release layer.

By the above manufacturing method, a release film including a polyester base material and a release layer is obtained. That is, it is preferable that the polyester base material is one obtained by stretching an unstretched polyester film in both the transport direction and the width direction.

Further, in the method for producing a release film of the present disclosure, particles are attached to the other surface of the polyester film 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 method may further include a step of forming a particle-containing layer by applying a composition for forming a particle-containing layer.

By the above manufacturing method, a polyester base material, a release layer placed on one side of the polyester base material, and particles placed on the side of the polyester base material opposite to the side where the release layer is placed. A release film is obtained, comprising a containing layer.

Each step in a preferred embodiment of the manufacturing method of the present disclosure will be described below. Note that the manufacturing method of the present disclosure is not limited to one preferred embodiment, and the following steps can be omitted as appropriate.

[Extrusion molding process]
The extrusion molding process is a process of forming an unstretched polyester film 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 film. The raw material polyester resin has the same meaning as the polyester resin explained in the item (Polyester resin) above.
In addition, in order to produce a polyester film that does not substantially contain particles, it is preferable to use polyester pellets that do not contain particles during extrusion molding.

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

[Stretching process]
The stretching process includes a first stretching process in which an unstretched polyester film is stretched in either the transport direction or the width direction to form a uniaxially stretched polyester film, and a uniaxially stretched polyester film is stretched in either the transport direction or the width direction. This is a step of carrying out stepwise or simultaneously a second stretching step of stretching in the other direction to form a biaxially stretched polyester film.
One of the first stretching process and the second stretching process is a longitudinal stretching process in which the polyester film is stretched in the transport direction (hereinafter also referred to as "longitudinal stretching"), and the other of the first stretching process and the second stretching process is This is a transverse stretching step in which the polyester film is stretched in the width direction (hereinafter also referred to as "lateral stretching"). During stretching, polyester polymers are 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 sequential biaxial stretching include, for example, an embodiment in which longitudinal stretching is performed in the order of transverse stretching; an embodiment in which longitudinal stretching is performed in the order of longitudinal stretching, lateral stretching, and longitudinal stretching; and an embodiment in which longitudinal stretching is performed in the order of longitudinal stretching, longitudinal stretching, and transverse stretching. It will be done. Among these, it is preferable that the sequential biaxial stretching is carried out in the order of longitudinal stretching and transverse stretching.
Hereinafter, an embodiment in which longitudinal stretching and transverse stretching are performed in this order will be described, but the above manufacturing method is not limited to this embodiment.

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

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

[Particle-containing layer formation process]
The particle-containing layer forming step is a step of applying a particle-containing layer forming composition to one surface of a polyester film to form a particle-containing layer.
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 forming step is preferably carried out between the first stretching step and the second stretching step. The particle-containing layer disposed on one surface of the polyester base material in the particle-containing layer forming step has the same meaning as the layer explained in the section of the particle-containing layer above.
Hereinafter, a mode of applying the particle-containing layer-forming composition will be described.

First, the composition for forming a particle-containing layer will be explained.
The composition for forming a particle-containing layer can be prepared by mixing the components described in the section of the particle-containing layer above and a solvent.
Examples of the solvent include water and alcohol.

The composition for forming a particle-containing layer may contain one type of solvent alone, or may contain two or more types of solvents.
The content of the solvent is preferably 80% by mass to 99.5% by mass, more preferably 90% by mass to 99% by mass, based on the total mass of the particle-containing layer-forming composition.
That is, in the composition for forming a particle-containing layer, the total content of components (solid content) other than the solvent is preferably 0.5% by mass to 20% by mass with respect to the total mass of the composition for forming a particle-containing layer. , more preferably 1% by mass to 10% by mass.

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 the preferable content of each component relative to the total mass of the above-mentioned particle-containing layer. It is preferable to adjust the content of each component in the composition for forming a particle-containing layer so that the content is the same as the content.

Moreover, the composition for forming a particle-containing layer may contain a crosslinking agent.
Examples of the crosslinking agent include the above-mentioned carbodiimide compound and the other crosslinking agents mentioned above.
The content of the crosslinking agent is preferably 0% by mass to 50% by mass based on the total mass of the particle-containing layer.
In the composition for forming a particle-containing layer, the mass ratio of the crosslinking agent to the binder is preferably 2% by mass to 50% by mass.

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

The heating temperature in 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 film and the particle-containing layer, the surface of the polyester film is subjected to pre-treatments such as anchor coating, corona treatment, and plasma treatment before forming the particle-containing layer. You can.

[Peeling layer formation process]
The release layer forming step is a step of applying a release layer forming composition to a polyester film to form a release 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.

Among them, from the viewpoint of adhesion between the release layer and the polyester base material, the release layer forming step is carried out between the extrusion molding step and the first stretching step, or between the first stretching step and the second stretching step. It is preferable that
That is, the step of forming a release layer is preferably a step of applying a release layer forming composition to one side of an unstretched polyester film or a uniaxially stretched polyester film to form a release layer.

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 the surface of the polyester film in the release layer forming step has the same meaning as the layer explained in the section of the release layer above.

First, the composition for forming a release layer will be explained.
The composition for forming a release layer preferably contains the components described in the section for the release layer above and a solvent.
Examples of the solvent include water, alcohol, ether, ketone, and aromatic hydrocarbon.

The release layer forming composition may contain one type of solvent alone, or may contain two or more types of 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 release layer.
That is, in the composition for forming a release layer, the total content of components (solid content) other than the solvent is preferably 0.5% by mass to 20% by mass, and 1% by mass based on the total mass of the composition for forming a release layer. More preferably, the amount is from % by mass to 10% by mass.

Regarding each component other than the solvent in the composition for forming a release layer, the content of each component relative to the total mass of the solid content of the composition for forming a release layer is the preferred content of each component relative to the total mass of the release layer described above. It is preferable to adjust the content of each component in the composition for forming a peeling layer so that they are the same.

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

The heating temperature in 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 film and the release layer, the surface of the polyester film may be subjected to pretreatment such as anchor coating, corona treatment, or plasma treatment before providing the release layer. good.

[Heat setting process]
The above method for producing a release film may include, after the stretching step, a heat setting step as a heat treatment for the polyester film obtained in the stretching step.
In the heat-setting step, the polyester film obtained in the stretching step can be heated and heat-set. By crystallizing the polyester resin through heat fixation, 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 fixing step is preferably 5 seconds to 50 seconds, more preferably 5 seconds to 30 seconds, even more preferably 5 seconds to 10 seconds.

[Thermal relaxation process]
The method for producing a release film of the present disclosure 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 it at a lower temperature than in the heat-setting step. Residual strain in the polyester film can be alleviated by thermal relaxation.
The surface temperature (thermal relaxation temperature) of the polyester film in the thermal 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 more. Low temperatures are particularly preferred. That is, the thermal relaxation temperature is preferably 235°C or lower, more preferably 225°C or lower, even 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 a release film of the present disclosure may include a cooling step of cooling the thermally relaxed polyester film.
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°C/min to 3500°C/min, and even more preferably more than 2200°C/min and less than 3000°C/min. Particularly preferred is 2300°C/min to 2800°C/min.
In the cooling step, it is also preferable to include a step of expanding the thermally relaxed polyester film in the width direction (expansion step).
The expansion rate in the width direction of the polyester film in the expansion step, that is, the ratio of the polyester film width at the end of the cooling step to the polyester film width before the start of the cooling step, is preferably 0% or more, and more preferably 0.001% or more. It is preferably 0.01% or more, and more preferably 0.01% or more.
The upper limit of the expansion rate is not particularly limited, but is preferably 1.3% or less, more preferably 1.2% or less, and even more preferably 1.0% or less.

[Winding process]
The method for manufacturing a release film of the present disclosure may include a winding step of obtaining a roll-shaped polyester film by winding up the polyester film obtained through the above steps.

[Trimming process]
The manufacturing method of the present disclosure includes 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 implementing the winding step. You can stay there.

[Other conditions]
The conveyance speed of the polyester film in each step other than the longitudinal stretching step of the method for producing a release film of the present disclosure is not particularly limited, but in the transverse stretching step, heat setting step, heat relaxation step, and cooling step, productivity and In terms of quality, the speed is preferably 50 m/min to 200 m/min, more preferably 80 m/min to 150 m/min.

Note that in the above manufacturing method, a method is described in which a particle-containing layer forming composition is applied to form a particle-containing layer in the particle-containing layer forming step, but the method for forming a particle-containing layer is not limited to the above embodiment. , a known method can be used. For example, a method of forming an unstretched polyester film on which particle-containing layers are laminated by coextrusion molding may be mentioned.

In particular, the method for producing a release film of the present disclosure includes:
a longitudinal stretching step of stretching an unstretched polyester film in the transport direction;
A step of applying a particle-containing layer forming composition to one side of the uniaxially stretched polyester film obtained in the longitudinal stretching step to form a particle-containing layer;
A step of applying a release layer forming composition to the other surface of the uniaxially stretched polyester film obtained in the longitudinal stretching step to form a release layer;
It is preferable to include a transverse stretching step of stretching a uniaxially stretched polyester film having a particle-containing layer and a release layer in the width direction while heating it.

[Uses of release film]
The release film is preferably a release film (carrier film) used for producing ceramic green sheets. Ceramic green sheets manufactured using the above release film can be suitably used in the manufacture of ceramic capacitors, which are required to have multilayer internal electrodes as miniaturization and capacity increases.

Further, the release film of the present disclosure is a protective film for dry film resist, a film for forming sheets such as decorative layers and resin sheets, a release film for process manufacturing such as semiconductor manufacturing process, and a release film for polarizing plate manufacturing process. It can also be used as a separator for adhesive films for labels, medical use, office supplies, etc.

[Laminated body]
The laminate of the present disclosure includes the release film described above and a ceramic-containing layer disposed on the release film.

Details of the release film are as described above.
The ceramic-containing layer may be provided directly on the surface of the release film or may be provided on the release film via another layer, but it is preferable to provide it directly on the surface of the release film because smoothness is better. is preferred.

Examples of the ceramic powder included in the ceramic-containing layer include ferroelectric materials such as barium titanate, and paraelectric materials such as titanium oxide and calcium titanate.

Preferably, the ceramic-containing layer includes a binder. The binder is not particularly limited, and examples thereof include polyvinyl butyral.

The laminate of the present disclosure can be manufactured, for example, by applying a ceramic slurry containing a ceramic and a solvent onto the release surface of a release film and drying the solvent contained in the ceramic slurry. Examples of the solvent include ethanol and toluene.

The method for applying the ceramic slurry is not particularly limited, and for example, known methods such as a reverse roll method can be applied.

The present disclosure will be described in more detail with reference to Examples below. The materials, amounts used, proportions, processing details, and processing procedures shown in the following examples can be changed as appropriate without departing from the spirit of the present disclosure. Therefore, the scope of the present disclosure is not limited to the specific examples shown below.

<Example 1>
(Extrusion molding process)
Pellets of polyethylene terephthalate were produced using a titanium compound (citric acid chelate titanium complex, VERTEC AC-420, manufactured by Johnson Matthey) described in Japanese Patent No. 5,575,671 as a polymerization catalyst. The obtained pellets were dried until the moisture content became 50 ppm or less, and then put into a hopper of a twin-screw kneading extruder. Then, it was melted and extruded at 280°C. The melt was passed through a filter (pore diameter: 3 μm) and then extruded from a die into a cooling drum at 25° C. to obtain a film (unstretched film) made of unstretched polyethylene terephthalate. The extruded melt was brought into close contact with the cooling drum by electrostatic application.

(Longitudinal stretching process)
A uniaxially stretched polyester film was produced by stretching the above-mentioned unstretched film in the longitudinal direction (conveyance direction) at 90°C and 3.4 times.

(Particle-containing layer formation process, peeling layer formation process)
A particle-containing layer forming composition A1 shown below was coated on one side of a polyester film uniaxially stretched in the longitudinal direction using a bar coater. A release layer forming composition L1 shown below was applied using a bar coater to the surface of the uniaxially stretched polyester film opposite to the surface on which the particle-containing layer was applied. The formed coating film was dried with hot air at 100° C. to form a particle-containing layer and a release layer. That is, the composition A1 for forming a particle-containing layer and the composition L1 for forming a release layer were in-line coated onto a uniaxially stretched polyester film. At this time, the particle-containing layer-forming composition A1 and the release layer-forming composition L1 were mixed so that the particle-containing layer had a thickness of 40 nm and the release layer had a thickness of 100 nm after lateral stretching, which will be described later. The amount of application was adjusted.

The polyester film that had been subjected to the longitudinal stretching step, the release layer forming step, and the particle-containing layer forming step was subjected to the following conditions using a tenter: a stretching temperature of 120° C., a stretching ratio of 4.2 times, and a stretching speed of 50%/sec. A biaxially stretched polyester film was produced by stretching in the width direction. Next, it was heat-set at a temperature of 227°C for 6 seconds, and further heat-relaxed by 4% at 190°C. Thereafter, the film was cooled at a rate of 2500° C./min, both ends of the film were trimmed, extrusion processing (knurling) was performed, and the film was wound up at a tension of 40 kg/m. The thickness of the obtained release film was 31 μm, the width was 1.5 m, and the winding length was 7000 m.

[Preparation of composition L1 for forming a peeling layer]
・Silicone compound: Silicone A (product name "X-22-3701E", manufactured by Shin-Etsu Chemical Co., Ltd., silicone compound having a carboxy group, solid content concentration 10% by mass diluted with water)...80 parts by mass ・Carbodiimide compound: carbodiimide A (product name "Carbodilite V-02-L2" carbodiimide equivalent weight 385, manufactured by Nisshinbo Chemical Co., Ltd., solid content concentration 10% by mass diluted liquid)...62.8 parts by mass, acid group-containing non-silicone resin: Urethane resin A ( Product name "Arrowbase SE1010", manufactured by Unitika Co., Ltd., solid content concentration 25% by mass aqueous dispersion)...100.6 parts by mass, surfactant A (product name "Naroacty CL95", Sanyo Chemical Industries, Ltd.) Co., Ltd., nonionic surfactant, solid content concentration 1% by mass aqueous solution) ... 32 parts by mass, surfactant B (product name "Rapizole (registered trademark) A-90", di-2-ethylhexyl sodium sulfosuccinate, NOF Co., Ltd., solid content concentration 1% by mass diluted with water)...24 parts by mass Distilled water...700 parts by mass

[Preparation of particle-containing layer forming composition A1]
・Crosslinked PMMA particles (Epostor (registered trademark) MX050W, manufactured by Nippon Shokubai Co., Ltd., average particle diameter 70 nm, solid content concentration 10% by mass aqueous dispersion)...8 parts by mass ・Urethane resin C (product name "Hydran (registered trademark) AP-40N", manufactured by DIC Corporation, aqueous dispersion with solid content adjusted to 25% by mass) ... 157 parts by mass, surfactant B (product name "Rapizol (registered trademark) A-90", sulfosuccinic acid dispersion) -2-Ethylhexyl sodium, manufactured by NOF Corporation, solid content concentration 1% by mass diluted with water)...56 parts by mass, water...779 parts by mass

<Example 2 to Example 20, Comparative Example 1>
Regarding the solid content contained in the composition for forming a release layer, the type and content (mass%) of each component were changed to those listed in Table 1, and the type of resin contained in the composition for forming a particle-containing layer was changed to the one listed in Table 1. A release film was produced in the same manner as in Example 1, except that the film was changed to that described in Example 1.

<Comparative Example 2 to Comparative Example 3>
Regarding the solid content contained in the composition for forming a release layer, the type and content (% by mass) of each component were changed to those listed in Table 1, and the composition for forming a release layer was prepared without providing a particle-containing layer. A release film was produced in the same manner as in Example 1, except that the surface of the uniaxially stretched polyester film was subjected to corona treatment before application.

Details of each component listed in Table 1 are as follows.

(Silicone compound)
・Silicone A: Silicone compound having a carboxy group (product name "X-22-3701E", manufactured by Shin-Etsu Chemical Co., Ltd.)
・Silicone B: Acrylic silicone composite resin (product name "Ceranate WSA1070", manufactured by DIC Corporation, solid content concentration 40% by mass)
・Silicone C: Product name "X-62-7655" (coating agent containing silicone component, manufactured by Shin-Etsu Chemical Co., Ltd.) and product name "X-62-7622" (coating agent containing silicone component, manufactured by Shin-Etsu Chemical Co., Ltd.) (manufactured by Shin-Etsu Chemical Co., Ltd.) and product name "CAT-7605" (catalyst, manufactured by Shin-Etsu Chemical Co., Ltd.) in a mass ratio of 95:5:1.

(Crosslinking agent)
・Carbodiimide A: Carbodiimide compound (product name "Carbodilite V-02-L2", carbodiimide equivalent weight 385, manufactured by Nisshinbo Chemical Co., Ltd.)
・Carbodiimide B: Carbodiimide compound (product name "Carbodilite V-02", carbodiimide equivalent weight 590, manufactured by Nisshinbo Chemical Co., Ltd.) ・Carbodiimide B: Carbodiimide compound (product name "Carbodilite V-04", carbodiimide equivalent weight 335, manufactured by Nisshinbo Chemical Co., Ltd.) ) Oxazoline A: Oxazoline compound (product name "Epocross WS-700", manufactured by Nippon Shokubai Co., Ltd.)
・Melamine A: Hexamethoxymelamine (manufactured by Tokyo Kasei Kogyo Co., Ltd.)

(non-silicone resin)
・Urethane resin A: Product name ``Arrowbase SE1010'', manufactured by Unitika Co., Ltd. ・Urethane resin B: Product name ``Superflex (registered trademark) 210'', manufactured by Daiichi Kogyo Seiyaku Co., Ltd. ・Urethane resin C: Product name "Hydran (registered trademark) AP-40N", manufactured by DIC Corporation, olefin resin: product name "Zaixen (registered trademark) NC", manufactured by Sumitomo Seika Co., Ltd., polyester resin: product name "Vylonal MD1245", Toyobo ( Co., Ltd. Acrylic resin: Acrylic resin prepared by the method described below / Long-chain alkyl group-containing resin: Long-chain alkyl group-containing resin prepared according to the method described in [0122] of International Publication No. 2020/017289

-Preparation of acrylic resin-
In a three-necked flask, add methyl methacrylate, hydroxyethyl methacrylate, and urethane acrylate oligomer (product name "Art Resin (registered trademark) UN-3320HA", manufactured by Negami Kogyo Co., Ltd., number of acryloyl groups is 6) in 94/1/ A monomer solution was obtained by adding 2 parts by mass of sodium dodecylbenzenesulfonate to a total of 100 parts by mass of monomers. In another reaction vessel, 60 parts by mass of the above monomer solution, 200 parts by mass of isopropyl alcohol, and 5 parts by mass of potassium persulfate were added, heated to 60° C., and stirred for 20 minutes to obtain a mixed solution A. Next, a mixed solution consisting of 40 parts by mass of the above monomer solution, 50 parts by mass of isopropyl alcohol, and 5 parts by mass of potassium persulfate was prepared, and added dropwise to the mixed solution A over 2 hours using a dropping funnel. After the dropwise addition was completed, the mixture was reacted for 2 hours while being heated to 60°C. After cooling the resulting reaction solution to 25°C, 60 parts by mass of 25% by mass aqueous ammonia and 900 parts by mass of pure water were added, and while heating to 60°C, isopropyl alcohol and unreacted monomers were distilled off under reduced pressure. , an aqueous dispersion of acrylic resin was obtained.

(surfactant)
・Surfactant A: Product name “NAROACTY CL95”, manufactured by Sanyo Chemical Industries, Ltd. ・Surfactant B: Product name “Rapizole (registered trademark) A-90”, manufactured by NOF Corporation ・Surfactant C :Product name "Plus Coat RY-2", manufactured by Gooh Chemical Industry Co., Ltd.

Using the produced release film, evaluation regarding release properties, solvent resistance, and defects was performed. The evaluation method is as follows.

<Releasability>
100 parts by mass of barium titanate powder (BaTiO ₃ ; manufactured by Sakai Chemical Industry Co., Ltd., product name "BT-03") as a ceramic powder, polyvinyl butyral resin as a binder (product name "S-LEC (registered trademark) B・K BM") -2'', manufactured by Sekisui Chemical Co., Ltd.) 8 parts by weight, 4 parts by weight of dioctyl phthalate as a plasticizer (product name ``Dioctyl phthalate Deka 1 grade'', manufactured by Kanto Chemical Co., Ltd.), and toluene and ethanol. 135 parts by mass of a liquid mixture (mass ratio 6:4) was mixed. A ceramic slurry was prepared by dispersing the mixture using a ball mill in the presence of zirconia beads and removing the beads from the resulting dispersion.
The release films produced in Examples and Comparative Examples were cut into pieces with a width of 250 mm and a length of 10 m. The cut release film was stored in an environment of normal temperature and normal humidity (25° C., 50% RH) for one week. The prepared ceramic slurry was applied to the entire peeled surface of the released release film after storage using a die coater so that the film thickness after drying was 3 μm. Thereafter, the obtained coating film was dried in a dryer at 100°C for 2 minutes. Thereby, a release film with ceramic green sheets was obtained.
A polyester adhesive tape (model number "No. 31B", manufactured by Nitto Denko Corporation) was attached to the surface of the ceramic green sheet in the release film with 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 test sample. The adhesive tape side of the test sample was fixed on the surface of a glass plate, and peeled with a ceramic green sheet using a Tensilon universal testing machine manufactured by A&D Co., Ltd. at a peeling angle of 180° and a peeling speed of 100 mm/min. The release film was peeled off from the film and the force required for peeling was measured. Peelability was evaluated based on the force required to peel. The evaluation criteria are as follows.
A: The force required for peeling was 45 mN or less.
B: The force required for peeling was more than 45 mN and less than 100 mN.
C: The force required for peeling was over 100 mN.

<Solvent resistance>
For the release films produced in Examples and Comparative Examples, the surface of the release layer was rubbed 5 times vertically at a load of 500 g/cm ² using a cloth impregnated with a mixed solution of methyl ethyl ketone and toluene (mass ratio 1:1). , horizontally polished 5 times. Thereafter, the surface of the release layer was visually observed, and the solvent resistance was evaluated based on the dissolution state of the release layer. The evaluation criteria are as follows.
A: The release layer was not dissolved at all.
B: The release layer was partially dissolved. C: The release layer was completely dissolved.

<Defect evaluation>
The release films obtained in each Example and each Comparative Example were stored in an environment of normal temperature and normal humidity for 3 months. The same method as described in the evaluation of peelability was used, except that the release film after being stored for 3 months was used and the amount of ceramic slurry applied was adjusted so that the film thickness after drying of the ceramic slurry was 1 μm. Thus, a release film with ceramic green sheets was obtained. After winding up the release film with the ceramic green sheet, a fluorescent lamp was illuminated from the release film side of the release film with the ceramic green sheet, and a 1 m ² area on the surface of the ceramic green sheet was visually observed to check for minute pinholes etc. The presence or absence of uneven shapes was confirmed. Defects were rated based on the number of defects identified. The evaluation criteria are as follows.
A: No unevenness defects were observed on the ceramic green sheet.
B: 1 to 10 uneven defects were observed on the ceramic green sheet.
C: Eleven or more uneven defects were confirmed on the ceramic green sheet.

In addition, when defect evaluation was performed using the same method as the above defect evaluation without storing the release films obtained in each example and each comparative example for 3 months, the evaluation results were all A. .

The evaluation results are shown in Table 1. In Table 1, the column for release layer lists the type and content (% by mass) of each component contained in the composition for forming a release layer. The content is the solid content of each component. In the particle-containing layer column, the type of resin contained in the composition for forming a particle-containing layer is listed.
When the silicone compound contains an acid group, "Y" is written, and when the silicone compound does not contain an acid group, "N" is written. Non-silicone resin means a resin other than silicone resin, and when it contains an acid group, it is written as "Y", and when it does not contain an acid group, it is written as "N". Moreover, "acid group-containing non-silicone resin/silicone compound" means the mass ratio of the content of the acid group-containing non-silicone resin to the content of the silicone compound. "Silicone compound/carbodiimide compound" means the mass ratio of the content of the silicone compound to the content of the carbodiimide compound.

The release films of Examples 1 to 20 include a polyester base material and a release layer, and the release layer is formed by crosslinking a composition containing a silicone compound and a carbodiimide compound, and also meets Conditions 1 and 20. It was found that since at least one of Conditions 2 was satisfied, the releasability and solvent resistance were excellent.

On the other hand, it was found that in the release films of Comparative Examples 1 and 2, the composition for forming a release layer did not contain a silicone compound, and the release properties were poor.

It was found that the release film of Comparative Example 3 had poor solvent resistance because the composition for forming the release layer did not contain a carbodiimide compound.

From Examples 14 to 17, when the mass ratio of the content of the acid group-containing non-silicone resin to the content of the silicone compound in the composition for forming a release layer is 1 to 30, the release property and solvent resistance are improved. I found it to be excellent.

In Example 16, the mass ratio of the content of the silicone compound to the content of the carbodiimide compound in the composition for forming a release layer was 0.1 or more, so compared to Example 17, the solvent resistance was excellent. I understand.
In Example 14, the mass ratio of the content of the silicone compound to the content of the carbodiimide compound in the composition for forming a release layer was 10 or more, so it was found that the release property was excellent compared to Example 15. .
From Examples 1, 2, 9, 10, 12, and 13, when the content of the carbodiimide compound in the composition for forming a release layer is 9% by mass or more, the solvent resistance It was found to be superior in terms of gender.

It was found that in Examples 1 and 19, since the particle-containing layer contained a non-polyester resin, the occurrence of uneven defects was suppressed compared to Example 18.

Claims (12)

including a polyester base material and a release layer,
A release film, wherein the release layer is formed by crosslinking a composition containing a silicone compound and a carbodiimide compound, and satisfies at least one of Conditions 1 and 2 below.
Condition 1: The silicone compound contains an acid group.
Condition 2: The composition further contains at least one acid group-containing non-silicone resin selected from the group consisting of acid group-containing urethane resins and acid group-containing olefin resins. The release film according to claim 1, which is used for producing ceramic green sheets. 3. The release film of claim 1 or claim 2, wherein the polyester substrate is substantially free of particles. The composition further contains the acid group-containing non-silicone resin,
The release film according to any one of claims 1 to 3, wherein a mass ratio of the content of the acid group-containing non-silicone resin to the content of the silicone compound in the composition is 1 to 30. . The release film according to any one of claims 1 to 4, wherein a mass ratio of the content of the silicone compound to the content of the carbodiimide compound in the composition is 0.1 to 10. The release film according to any one of claims 1 to 5, wherein the release layer has a thickness of 0.001 μm to 0.2 μm. further comprising a particle-containing layer;
The release film according to any one of claims 1 to 6, comprising the release layer, the polyester base material, and the particle-containing layer in this order. The release film according to claim 7, wherein the particle-containing layer contains a non-polyester resin. The release film according to claim 8, wherein the non-polyester resin is at least one resin selected from the group consisting of acrylic resin, urethane resin, and olefin resin. A method for producing a release film comprising a polyester base material and a release layer,
A method for producing a release film, comprising the step of forming a release layer using a release layer forming composition containing a silicone compound and a carbodiimide compound. According to claim 10, the step of forming the release layer is a step of applying the release layer forming composition to one side of an unstretched polyester film or a uniaxially stretched polyester film to form a release layer. A method for producing a release film. A laminate comprising the release film according to any one of claims 1 to 9 and a layer containing ceramic.