Release film, method for manufacturing release film, and laminate

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

[Technical Field]

[0001] This disclosure relates to a release film, a method for manufacturing a release film, and a laminate. [Background technology]

[0002] As electronic devices become more high-performance and smaller, there is a growing demand for higher performance and smaller size in the electronic components used in them. Among electronic components, multilayer ceramic capacitors, for example, are seeing an increase in the number of points mounted on a circuit board, and there is a strong demand for miniaturization. In the manufacture of multilayer ceramic capacitors, a common method involves applying a ceramic slurry onto a release film having a release layer and drying it to form a ceramic green sheet.

[0003] For example, Patent Document 1 describes a release film comprising a polyester film and a release layer, wherein the polyester film has a release layer on at least one side, either directly or via another layer, and the release layer is formed by curing a composition containing an acrylic resin having a long-chain alkyl group and at least one crosslinking agent selected from oxazoline-based crosslinking agents or carbodiimide-based crosslinking agents. Patent Document 2 describes a laminated polyester film characterized by having a coating layer on at least one side of a polyester film, formed from a coating solution containing a crosslinking agent and a release agent, and further containing other polymers in a proportion of 30% by weight or less as nonvolatile components. Patent Document 3 describes a laminated film having a resin layer on at least one side of a polyester film, wherein 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 when the haze of the laminated film is H1 (%) and the haze after solvent immersion and abrasion testing of the laminated film is H2 (%), |H2-H1| ≤ 1.0 (%). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2020 / 129962 [Patent Document 2] Japanese Patent Publication No. 2016-30378 [Patent Document 3] International Publication No. 2020 / 017289 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, in the case of release films, there are times when improved release properties and solvent resistance are required. In particular, when the release film is used for the manufacture of ceramic green sheets, there was room for improvement in terms of release properties from the ceramic green sheet and solvent resistance when ceramic slurry is applied to the release film.

[0006] This disclosure has been made in view of the above circumstances, and the problem that one embodiment of the present invention aims to solve is to provide a release film with excellent peelability and solvent resistance, and a method for manufacturing a release film, and in particular to provide a release film with excellent peelability from ceramic green sheets and solvent resistance when coated with ceramic slurry, and a method for manufacturing a release film. Furthermore, other embodiments of the present invention aim to solve the problem of providing a laminate including a release film that is excellent in peelability and solvent resistance, and in particular, to provide a laminate including a release film that is excellent in peelability from a ceramic green sheet and in solvent resistance when a ceramic slurry is applied. [Means for solving the problem]

[0007] This disclosure includes the following aspects. <1> A release film comprising a polyester substrate and a release layer, wherein 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. Condition 1: The silicone compound contains an acidic group. Condition 2: The composition further contains at least one acid group-containing nonsilicone resin selected from the group consisting of acid group-containing urethane resins and acid group-containing olefin resins. <2> For the manufacture of ceramic green sheets, <1> The release film described above. <3> The polyester substrate is substantially free of particles. <1> or <2> The release film described above. <4> The composition further contains an acid group-containing non-silicone resin, and the mass ratio of the acid group-containing non-silicone resin to the silicone compound content in the composition is 1 to 30. <1> ~ <3> The release film described in any one of the following. <5> In the composition, the mass ratio of the content of the silicone compound to the content of the carbodiimide compound is 0.1 to 10. <1> ~ <4> The release film described in any one of the following. <6> The thickness of the delamination layer is 0.001 μm to 0.2 μm. <1> ~ <5> The release film described in any one of the following. <7> It further comprises a particle-containing layer, and includes a release layer, a polyester substrate, and a particle-containing layer in this order. <1> ~ <6> The release film described in any one of the following. <8> The particle-containing layer contains a non-polyester resin. <7> The release film described above. <9> The non-polyester resin is at least one resin selected from the group consisting of acrylic resin, urethane resin, and olefin resin. <8> The release film described above. <10> A method for manufacturing a release film comprising a polyester substrate 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> The step of forming a release layer involves 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. <10> A method for manufacturing the release film described above. A laminate comprising a release film according to any one of <12><1> to <9> and a layer containing a ceramic.

Advantages of the Invention

[0008] According to one embodiment of the present invention, there are provided a release film excellent in releasability and solvent resistance, and a method for producing the release film, particularly, a release film excellent in releasability from a ceramic green sheet and solvent resistance when a ceramic slurry is applied, and a method for producing the release film. Further, according to another embodiment of the present invention, there is provided a laminate including a release film excellent in releasability and solvent resistance, particularly, a laminate including a release film excellent in releasability from a ceramic green sheet and solvent resistance when a ceramic slurry is applied.

Modes for Carrying Out the Invention

[0009] Hereinafter, the release film, the method for producing the release film, and the laminate of the present disclosure will be described in detail.

[0010] In this specification, a numerical range indicated by using "~" means a range including the numerical values described before and after "~" as the minimum value and the maximum value, respectively. In the numerical ranges described stepwise in this specification, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in other stepwise descriptions. Also, in the numerical ranges described in this specification, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the value shown in the examples.

[0011] In this specification, the amount of each component in the composition means the total amount of a plurality of substances present in the composition when there are a plurality of substances corresponding to each component in the composition, unless otherwise specified. In this specification, a combination of two or more preferred embodiments is a more preferred embodiment. In this specification, the term "step" includes not only an independent step but also a step that cannot be clearly distinguished from other steps, provided that the intended purpose of the step is achieved.

[0012] In this specification, the "longitudinal direction" means the long dimension direction of the release film during the production of the release film, and is synonymous with the "transport direction" and the "machine direction". In this specification, the "width direction" means a direction perpendicular to the longitudinal direction. In this specification, "orthogonal" is not limited to strict orthogonality and includes approximate orthogonality. "Approximate orthogonality" means intersecting within a range of 90° ± 5°, preferably within a range of 90° ± 3°, and more preferably within a range of 90° ± 1°. Also, in this specification, the "film width" means the distance between both ends in the width direction of the release film.

[0013] 〔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 at least one of the following Condition 1 and Condition 2. 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 an acid group-containing urethane resin and an acid group-containing olefin resin.

[0014] According to the release film of the present disclosure, it is excellent in releasability and solvent resistance. Although the reason is not clear, it is speculated as follows.

[0015] In the release film of this disclosure, the release layer is obtained by crosslinking a composition containing a silicone compound and a carbodiimide compound. The release layer is obtained by crosslinking the carbodiimide compound with a component contained in the above composition. The component crosslinked with the carbodiimide compound may be a silicone compound or a component other than a silicone compound. If the silicone compound in the release layer contains an acid group, it is thought that the carbodiimide compound reacts with the silicone compound containing the acid group and crosslinks. Furthermore, if 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, it is thought that the carbodiimide compound crosslinks with this non-silicone resin. Because the release layer contains a crosslinked body based on the carbodiimide compound, it has excellent solvent resistance. Because the release layer contains a silicone compound and a crosslinked body having a structure derived from the silicone compound, it has excellent release properties. Furthermore, it is believed that the silicone compound contained in the release layer-forming composition is unevenly distributed on the surface, making the surface hydrophobic, and the non-silicone resin crosslinks with the carbodiimide compound inside the release layer, resulting in superior release properties and solvent resistance.

[0016] In contrast, Patent Documents 1 and 3 do not contain any descriptions of silicone compounds containing acid groups, urethane resins containing acid groups, or olefin resins containing acid groups. Patent Document 2 does not contain any descriptions focusing on silicone compounds.

[0017] <Polyester base material> A polyester substrate is a film-like object containing polyester resin as its main polymer component. Here, "main polymer component" refers to the polymer that is present in the largest quantity (by mass) of all polymers contained in the film-like object. The polyester substrate may contain one type of polyester resin, or it may contain two or more types of polyester resins.

[0018] [Polyester resin] Polyester resins are polymers having ester bonds in their main chain. Polyester resins are usually formed by polycondensation of dicarboxylic acid compounds and diol compounds, as described later. In this disclosure, "main chain" means the relatively longest bonding chain in the polymer compound that constitutes the resin. The polyester resin is not particularly limited, and known polyester resins can be used. Examples of polyester resins include polyethylene terephthalate (PET), polyethylene-2,6-naphthalate (PEN), polypropylene terephthalate (PPT), polybutylene terephthalate (PBT), and copolymers thereof. Among these, at least one selected from the group consisting of PET, PEN, and copolymers thereof is preferred, with PET being more preferred.

[0019] The intrinsic viscosity of the polyester resin is preferably 0.50 dl / g or more and less than 0.80 dl / g, and 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, and more preferably 245°C to 265°C. The glass transition temperature (Tg) of the polyester resin is preferably 65°C to 90°C, and more preferably 70°C to 85°C.

[0020] The method for producing polyester resin is not particularly limited, and known methods can be used. For example, polyester resin can be produced by polycondensation of at least one dicarboxylic acid compound and at least one diol compound in the presence of a catalyst. The following describes the materials used in the manufacture of polyester and the manufacturing conditions.

[0021] (Dicarboxylic acid compounds) Examples of dicarboxylic acid compounds include aliphatic dicarboxylic acid compounds, alicyclic dicarboxylic acid compounds, and aromatic dicarboxylic acid compounds, as well as dicarboxylic acid esters such as methyl ester compounds and ethyl ester compounds of these dicarboxylic acids. Among these, aromatic dicarboxylic acids or methyl aromatic dicarboxylic acids are preferred.

[0022] Examples of aliphatic dicarboxylic acid compounds include malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, dodecanedionic acid, dimer acid, eicosanedionic acid, pimelic acid, azelaic acid, methylmalonic acid, and ethylmalonic acid. Examples of alicyclic dicarboxylic acid compounds include adamantanedicarboxylic acid, norbornenedicarboxylic acid, cyclohexanedicarboxylic acid, and decalindicarboxylic acid.

[0023] Examples of aromatic dicarboxylic acid compounds include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 5-sodium sulfisoisophthalic acid, phenylindanedicarboxylic acid, anthracenedicarboxylic acid, phenantradicarboxylic acid, and 9,9'-bis(4-carboxyphenyl)fluorenic acid, as well as their methyl esters. Among these, terephthalic acid or 2,6-naphthalenedicarboxylic acid is preferred, with terephthalic acid being more preferred.

[0024] Dicarboxylic acid compounds may be used individually or in combination of two or more. When terephthalic acid is used as the dicarboxylic acid compound, it may be used alone or copolymerized with other aromatic dicarboxylic acids such as isophthalic acid, or with aliphatic dicarboxylic acids.

[0025] (Diol compounds) Examples of diol compounds include aliphatic diol compounds, alicyclic diol compounds, and aromatic diol compounds, with aliphatic diol compounds being preferred.

[0026] Examples of aliphatic diol compounds include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,2-butanediol, 1,3-butanediol, and neopentyl glycol, with ethylene glycol being preferred. Examples of alicyclic diol compounds include cyclohexanedimethanol, spiroglycol, and isosorbide. Examples of aromatic diol compounds include bisphenol A, 1,3-benzenedimethanol, 1,4-benzenedimethanol, and 9,9'-bis(4-hydroxyphenyl)fluorene. Diol compounds may be used individually or in combination of two or more.

[0027] (catalyst) The catalyst used in the production of polyester resin is not particularly limited, and any known catalyst usable for the synthesis of polyester resin can be used. Examples of catalysts include alkali metal compounds (e.g., potassium compounds, sodium compounds), alkaline earth metal compounds (e.g., calcium compounds, magnesium compounds), zinc compounds, lead compounds, manganese compounds, cobalt compounds, aluminum compounds, antimony compounds, titanium compounds, germanium compounds, and phosphorus compounds. Among these, titanium compounds are preferred from the viewpoint of catalytic activity and cost. The catalyst may be used alone or in combination of two or more. It is preferable to use 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 in combination with a phosphorus compound, and more preferably to use a titanium compound and a phosphorus compound in combination.

[0028] As the titanium compound, organic chelate titanium complexes are preferred. Organic chelate titanium complexes are titanium compounds that have an organic acid as a ligand. Examples of organic acids include citric acid, lactic acid, trimellitic acid, and malic acid. As a titanium compound, the titanium compounds described in paragraphs

[0049] to

[0053] of Japanese Patent Publication No. 5575671 can also be used, and the contents of the above publication are incorporated herein by reference.

[0029] (Terminal encapsulant) In the manufacture of polyester resin, end encapsulants may be used as needed. By using end encapsulants, structures derived from the end encapsulant are introduced to the ends of the polyester resin. The end-captive agent is not limited, and known end-captive agents can be used. Examples of end-captive agents include oxazoline compounds, carbodiimide compounds, and epoxy compounds. As end-capturing agents, refer to the contents described in paragraphs

[0055] to

[0064] of Japanese Patent Publication No. 2014-189002, and the contents of the above publication are incorporated herein by reference.

[0030] (Manufacturing conditions) The reaction temperature when manufacturing polyester resin is not limited and can be set appropriately depending on the raw materials. The reaction temperature is preferably 260°C to 300°C, and more preferably 275°C to 285°C. The pressure used when manufacturing polyester resin is not limited and should be set appropriately according to the raw materials. The pressure is 1.33 × 10⁻⁶. -3 ~1.33 × 10 -5 MPa is preferred, 6.67 × 10 -4 ~6.67×10 -5 MPa is more preferable.

[0031] As a method for synthesizing polyester resin, the method described in paragraphs

[0033] to

[0070] of Japanese Patent Publication No. 5575671 can also be used, and the contents of the above publication are incorporated herein.

[0032] [Content of each ingredient] The polyester resin content in the polyester substrate is preferably 85% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 98% by mass or more, based on the total mass of the polymer in the polyester substrate. There is no particular upper limit to the polyester resin content, and it can be appropriately set within a range of, for example, 100% by mass or less relative to the total mass of the polymer in the polyester substrate. When the polyester substrate contains polyethylene terephthalate, the polyethylene terephthalate content is preferably 90% to 100% by mass, more preferably 95% to 100% by mass, even more preferably 98% to 100% by mass, and particularly preferably 100% by mass, based on the total mass of polyester resin in the polyester substrate.

[0033] The polyester substrate may contain components other than polyester resin (for example, catalysts, unreacted raw material components, particles, and water).

[0034] From the viewpoint of improving the smoothness of the release film, it is preferable that the polyester substrate is substantially free of particles. Examples of particles include those contained in the particle-containing layer described later. "Substantially particle-free" is defined as a polyester substrate in which, when elements derived from particles are quantitatively analyzed by X-ray fluorescence analysis, the particle content is 50 ppm by mass or less relative to the total mass of the polyester substrate, preferably 10 ppm by mass or less, and more preferably below the detection limit. This is because even without actively adding particles to the polyester substrate, contaminants derived from foreign substances, raw resins, or dirt adhering to the lines or equipment in the manufacturing process of the polyester substrate may detach and become mixed into the polyester substrate.

[0035] [Properties of polyester substrates] (Orientation) The polyester substrate is preferably a biaxially oriented polyester substrate. "Biaxial orientation" means the property of having molecular orientation in two axial directions. The molecular orientation is measured using a microwave transmission type molecular orientation meter (for example, MOA-6004, manufactured by Oji Scientific Instruments Co., Ltd.). The angle formed by the two axial directions is preferably within the range of 90° ± 5°, more preferably within the range of 90° ± 3°, and 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 later.

[0036] (Density) The density of the polyester base material is preferably 1.39 g / cm 3 ~1.41 g / cm 3 and more preferably 1.395 g / cm 3 ~1.405 g / cm 3 and even more preferably 1.398 g / cm 3 ~1.400 g / cm 3 . The density of the polyester base material can be measured using an electronic specific gravity meter (product name "SD-200L", manufactured by Alpha Mirage Co., Ltd.).

[0037] (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 in terms of controlling peelability. The lower limit of the thickness is not particularly limited, but in terms of improving strength and processability, 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 is the arithmetic mean value of the thicknesses of five locations of the above-mentioned section, which is measured by preparing a section having a cross-section perpendicular to the main surface of the release film and using a scanning electron microscope (SEM: Scanning Electron Microscope) or a transmission electron microscope (TEM: Transmission Electron Microscope).

[0038] <Release layer> A release layer is provided to allow the release film to be peeled off. When the release film is used to manufacture a ceramic green sheet, the ceramic green sheet is formed on the release surface, which is the surface of the release layer opposite to the polyester substrate. That is, the ceramic green sheet is provided on the release surface of the release film in a peelable manner. The release layer may be provided directly on the surface of the polyester substrate, or it may be provided on the polyester substrate via another layer, but it is preferable to provide it directly on the surface of the polyester substrate in terms of superior smoothness.

[0039] The release layer is formed by crosslinking a composition containing a silicone compound and a carbodiimide compound. Hereinafter, the composition containing the silicone compound and the carbodiimide compound will also be referred to as the "release layer forming composition."

[0040] [Silicone compounds] The release layer-forming composition contains a silicone compound. The presence of a silicone compound results in a release layer with excellent release properties.

[0041] The silicone compound is not particularly limited as long as it is a compound having a siloxane bond in its molecule. The silicone compound is preferably a compound having a dimethylsiloxane structure because it exhibits superior release properties. The silicone compound may be a low molecular weight compound, an oligomer, or a resin, but it is preferably an oligomer or a resin.

[0042] 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, for example, 1 million. The weight-average molecular weight of the silicone compound is preferably 100,000 or less, and more preferably 10,000 or less.

[0043] In this disclosure, weight-average molecular weight (Mw) refers to the value measured by gel permeation chromatography (GPC). For molecular weights of 1000 or less, the molecular weight is calculated based on the types and number of atoms constituting the compound.

[0044] GPC measurements are performed using the HLC(registered trademark)-8020GPC (Tosoh Corporation) as the measuring device, with three TSKgel(registered trademark) Super Multipore HZ-H columns (4.6 mm ID × 15 cm, Tosoh Corporation) and THF (tetrahydrofuran) as the eluent. The measurement conditions are a sample concentration of 0.45 mass%, a flow rate of 0.35 ml / min, a sample injection volume of 10 μL, and a measurement temperature of 40°C, and are performed using an RI detector. The calibration curve will be prepared using eight samples from Tosoh Corporation's "Standard Samples TSK standard, polystyrene": "F-40", "F-20", "F-4", "F-1", "A-5000", "A-2500", "A-1000", and "n-propylbenzene".

[0045] As for the silicone compound, a crosslinkable silicone compound is preferred because it has superior solvent resistance. The component that the silicone compound crosslinks may be a carbodiimide compound or other components contained in the release layer, and it is preferable that the crosslinkable portion is introduced to at least one of the terminal and side chains of the silicone compound.

[0046] Examples of silicone compounds include polydimethylsiloxane and hydrodienesiloxane, which have a vinyl group introduced to at least one of their terminal and side chains. These silicone compounds exhibit superior solvent resistance because crosslinked products are obtained by reacting them with a platinum catalyst. Examples of silicone compounds include polydimethylsiloxanes having hydroxyl groups at their ends and polydimethylsiloxanes having hydrogen atoms at their ends. These silicone compounds exhibit superior solvent resistance because crosslinked products are obtained by condensation reactions using organotin catalysts. Furthermore, the silicone compound may be a silicone compound that can be crosslinked by ultraviolet light or electron beams. Examples of silicone compounds that can be crosslinked by ultraviolet light or electron beams include radical polymerizable silicone compounds and silicone compounds having epoxy groups, and more specifically, acrylate-modified polydimethylsiloxane and glycidoxy-modified polydimethylsiloxane.

[0047] In particular, from the viewpoint of crosslinking with carbodiimide compounds, silicone compounds preferably contain acidic groups, and more preferably contain acidic groups at least one of the terminal and side chains of the silicone compound. When acidic groups are included in the silicone compound, the hydrophobic surface hardens through crosslinking, which further improves solvent resistance.

[0048] Examples of acidic groups include carboxyl groups, sulfol groups, phosphonic acid groups, and phosphate groups. Among these, from the viewpoint of crosslinkability with carbodiimide compounds, the acidic group is preferably a carboxyl group. In other words, it is preferable for the silicone compound to have a carboxyl group.

[0049] The composition for forming the release layer may contain only one silicone compound, or two or more. In the composition for forming the release layer, the silicone compound is preferably a silicone compound containing an acid group, and a combination of a silicone compound containing an acid group and a ricone compound that does not contain an acid group may also be used.

[0050] The content of the silicone compound is preferably 1% to 90% by mass, relative to the total solid content of the release layer forming composition, and more preferably 5% to 76% by mass, in terms of superior release properties and solvent resistance. In this disclosure, the solid content refers to the total mass of the release layer forming composition excluding liquid components such as water and solvents.

[0051] [Carbodiimide compounds] The release layer-forming composition contains a carbodiimide compound. The presence of a carbodiimide compound provides excellent solvent resistance to the release layer.

[0052] Since carbodiimide compounds function as crosslinking agents, the inclusion of a crosslinked material based on carbodiimide compounds in the release layer makes the release layer more hydrophobic and improves its solvent resistance. Furthermore, because the crosslinked material based on carbodiimide compounds has excellent flexibility, for example, when a stretching process is performed after applying the release layer-forming composition to a polyester film (described later), the film formed by the application of the release layer-forming composition also stretches, making it less likely for minute defects such as cracks to occur in the release layer. As a result, it is thought that minute irregularities and defects can be suppressed even when applied to the manufacture of ceramic green sheets.

[0053] Carbodiimide compounds can be synthesized by conventionally known methods. For example, condensation reactions of diisocyanate compounds are used. The diisocyanate compound is not particularly limited and may be an aromatic diisocyanate, an aliphatic diisocyanate, or an alicyclic diisocyanate.

[0054] Examples of aromatic diisocyanates include 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyle diisocyanate, tetraalkyldiphenylmethane diisocyanate, dialkyldiphenylmethane diisocyanate, 1,3-phenylenediisocyanate, polymeric diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 1,5-naphthylene diisocyanate, and naphthalene diisocyanate.

[0055] Examples of aliphatic diisocyanates include hexamethylene diisocyanate, trimethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, xylylene diisocyanate, 1,2-propylene diisocyanate, butylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, and 1,5-pentamethylene diisocyanate.

[0056] Examples of alicyclic diisocyanates include 1,3-cyclopentane diisocyanate, 1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, 3-isocyanate-methyl-3,5,5-trimethylcyclohexyl isocyanate, 2,4-methylcyclohexane diisocyanate, 2,6-methylcyclohexane diisocyanate, and norbornane diisocyanate.

[0057] The carbodiimide equivalent (the mass [g] of the carbodiimide compound required to yield 1 mole of carbodiimide groups) is preferably 100 g / mol to 1000 g / mol, more preferably 250 g / mol to 800 g / mol, and even more preferably 300 g / mol to 700 g / mol.

[0058] The composition for forming the release layer may contain only one carbodiimide compound, or two or more compounds.

[0059] The content of the carbodiimide compound is preferably 1% by mass or more, relative to the total solid content of the release layer forming composition, and more preferably 9% by mass or more, in terms of superior solvent resistance. The upper limit of the content of the carbodiimide compound is, for example, 80% by mass or less. In terms of superior release properties, the content of the carbodiimide compound is preferably less than 29% by mass, and more preferably 28% by mass or less.

[0060] In the composition for forming the release layer, the mass ratio of the silicone compound to the carbodiimide compound is preferably 0.05 to 10, more preferably 0.1 to 10, and even more preferably 0.3 to 6, for superior release properties and solvent resistance. When the mass ratio is 0.1 or higher, the release properties are improved. On the other hand, when the mass ratio is 10 or lower, the solvent resistance is improved.

[0061] [Non-silicone resin containing acid groups] The release layer forming composition preferably further comprises 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. An acid group-containing non-silicone resin means a non-silicone resin that contains acid groups. The inclusion of an acid group-containing non-silicone resin increases the crosslinking density, further improving solvent resistance. Furthermore, it is believed that the silicone compound contained in the release layer-forming composition is unevenly distributed on the surface, making the surface hydrophobic, and the non-silicone resin crosslinks with the carbodiimide compound within the release layer, resulting in superior release properties and solvent resistance.

[0062] Examples of acidic groups include carboxyl groups, sulfol groups, phosphonic acid groups, and phosphate groups. Among these, carboxyl groups are preferred from the viewpoint of crosslinking with carbodiimide compounds.

[0063] The urethane resin is not limited as long as it is a polymer having urethane bonds in its main chain, and known urethane resins such as reaction products of polyisocyanate compounds and polyol compounds can be used. Examples of commercially available acid group-containing urethane resins include Hydran® AP-20, AP-40N, and AP-201 (all manufactured by DIC Corporation), Takelac® W-605, W-5030, and W-5920 (all manufactured by Mitsui Chemicals, Inc.), Superflex® 210 and 130, and Elastron® H-3-DF, E-37, and H-15 (all manufactured by Daiichi Kogyo Seiyaku Co., Ltd.).

[0064] An olefin resin is any resin that contains constituent units derived from olefins 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 in the polyolefin are preferably 50 mol% to 99 mol%, and more preferably 60 mol% to 98 mol%, relative to all structural units of the polyolefin.

[0065] Examples of acid-containing olefin resins include copolymers obtained by modifying the above-mentioned olefin resin with an acid-modifying component such as an unsaturated carboxylic acid or its anhydride.

[0066] Examples of commercially available acid group-containing olefin resins include the Zaixen® series (manufactured by Sumitomo Seika Co., Ltd.), such as Zaixen AC, A, L, NC, and N; the Chemipearl® series (manufactured by Mitsui Chemicals, Inc.), such as Chemipearl S100, S120, S200, S300, S650, and SA100; and the Hitec® series (manufactured by Toho Co., Ltd.), such as Hitec S3121 and S3148K. Examples include the Arrowbase® series (manufactured by Unitika Ltd.), such as Arrowbase SE-1013, SE-1010, SB-1200, SD-1200, SD-1200, DA-1010 and DB-4010, Hardlen AP-2, NZ-1004 and NZ-1005 (manufactured by Toyobo Co., Ltd.), and Sepolion G315 and VA407 (manufactured by Sumitomo Seika Co., Ltd.). Furthermore, the acid-modified olefin resin described in paragraphs

[0022] to

[0034] of Japanese Patent Publication No. 2014-076632 can also be preferably used.

[0067] As stated above, the silicone compound included in the release layer forming composition may be a silicone compound containing an acid group.

[0068] The release film of this disclosure has a release layer that satisfies at least one of the following conditions 1 and 2. Condition 1: The silicone compound contains an acidic 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.

[0069] In the release layer forming composition, there may be only one type of acid group-containing non-silicone resin, or there may be two or more types.

[0070] In the release layer forming composition, the content of the acid group-containing non-silicone resin is preferably 0% to 80% by mass, relative to the total solid content of the release layer forming composition, and more preferably 15% to 68% by mass, in terms of superior release properties and solvent resistance.

[0071] In the release layer forming composition, the mass ratio of the acid group-containing non-silicone resin to the silicone compound content is preferably 0.1 to 50, and more preferably 1 to 30 in terms of superior release properties and solvent resistance. When the above mass ratio is 1 or higher, solvent resistance is improved. On the other hand, when the above mass ratio is 30 or lower, release properties are improved.

[0072] [Additives] The release layer may contain additives other than the components mentioned above. These additives may include surfactants, light and heavy release additives to adjust the release force, adhesion enhancers, and antistatic agents. As the surfactant, the same surfactant as that used in the particle-containing layer can be used. The preferred embodiment of the surfactant that may be contained in the release layer is the same as the preferred embodiment of the surfactant that may be contained in the particle-containing layer.

[0073] The release layer-forming composition may contain hydrophilic monomers such as polyalkylene oxides, quaternary ammonium salts of dialkylamino alcohols, or hydroxyalkyl sulfonates to improve the water solubility or water dispersibility of the carbodiimide compound. The release layer-forming composition may also contain a crosslinking catalyst to promote the crosslinking reaction by the carbodiimide compound. Furthermore, the composition for forming the release layer may also contain other crosslinking agents besides carbodiimide compounds. Other crosslinking agents are not particularly limited and known ones can be used. Other crosslinking agents include, for example, melamine compounds, oxazoline compounds, epoxy compounds, and isocyanate compounds. For details on melamine compounds, epoxy compounds, and isocyanate compounds, refer to sections

[0081] to

[0083] of Japanese Patent Publication No. 2015-163457. Crosslinking agents described in sections

[0082] to

[0084] of International Publication No. 2017 / 169844 can also be preferably used. For oxazoline compounds and isocyanate compounds, see International Publication No. 2018 / 034294.

[0074] ~

[0075] The crosslinking agents described can also be preferably used.

[0074] When a carbodiimide compound is used in combination with another crosslinking agent, the other crosslinking agent is preferably an oxazoline compound.

[0075] If the release layer forming composition contains other crosslinking agents, the content of the other crosslinking agents is preferably 0.1% to 20% by mass relative to the total solid content of the release layer forming composition.

[0076] [Properties of the release layer] (Thickness) The thickness of the release layer can be set according to its intended use and is not particularly limited, but 0.001 μm to 0.2 μm is preferred, 0.01 μm to 0.2 μm is more preferred, and 0.03 μm to 0.1 μm is even more preferred, as it provides a good balance between release performance and smoothness of the release surface. The thickness of the release layer is determined by preparing a section of the release film with a cross-section perpendicular to the main surface, and measuring the thickness at five points on the section using a scanning electron microscope (SEM) or transmission electron microscope (TEM), and taking the arithmetic mean of the thicknesses of these sections.

[0077] <Particle-containing layer> The release film of this disclosure preferably further comprises a particle-containing layer, and more preferably comprises the release layer, polyester substrate, and particle-containing layer in this order.

[0078] A particle-containing layer refers to a layer that contains particles. The presence of a particle-containing layer in the release film improves its transportability. Specifically, it improves winding quality (suppresses blocking), reduces the occurrence of scratches and defects during transport, and reduces transport wrinkles during high-speed transport.

[0079] The particle-containing layer may be provided directly on the surface of the polyester substrate, or it may be provided on the surface of the polyester substrate via another layer, but it is preferable to provide it directly on the surface of the polyester substrate in terms of superior adhesion.

[0080] Furthermore, the particle-containing layer preferably contains particles and a binder, and may also contain additives.

[0081] The following describes the particles, binder, and additives.

[0082] (particle) The average particle size of the particles contained in the particle-containing layer is not particularly limited, but is preferably 10 nm to 2 μm, more preferably 30 nm to 1.5 μm, and even more preferably 30 nm to 500 nm, in terms of superior transportability and suppression of transfer marks. Furthermore, in terms of superior transportability and suppression of transfer marks, it is preferable that 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), the thickness of the particle-containing layer is 1 nm to 200 nm (more preferably 10 nm to 100 nm), and the average particle diameter of the particles is greater than the thickness of the particle-containing layer.

[0083] The particles contained in the particle-containing layer may be one type alone, or two or more types of particles may be used. When the particle-containing layer contains two or more particles with different particle sizes, it is preferable that the particle-containing layer contains at least one particle whose average particle size is within the above range, and it is more preferable that all two or more particles with different particle sizes have an average particle size within the above range.

[0084] Examples of particles included in the particle-containing layer include organic particles and inorganic particles. Among these, organic particles are preferred from the viewpoint of suppressing the defect rate of ceramic capacitors manufactured using the obtained ceramic green sheet when the ceramic green sheet is manufactured. As organic particles, resin particles are preferred. Examples of resins constituting the resin particles include acrylic resins such as polymethyl methacrylate (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. In this disclosure, "acrylic resin" means a resin containing constituent units derived from acrylate or methacrylate. Examples of 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, silica particles are preferred as the inorganic particles from the viewpoint of improving haze and durability.

[0085] The shape of the particles is not particularly limited and can be, for example, rice grain-shaped, spherical, cubic, spindle-shaped, flaky, aggregated, or irregular. Aggregated means a state in which primary particles are aggregated. The shape of the aggregated particles is not limited, but spherical or irregular shapes are preferred.

[0086] As the aggregated particles, fumed silica particles are preferred. A commercially available example is the Aerosil series from Nippon Aerosil Co., Ltd. Colloidal silica particles are preferred as non-aggregated particles. Examples of commercially available products include the Snowtex series manufactured by Nissan Chemical Corporation.

[0087] From the viewpoint of transportability and the ability to suppress transfer marks, the particle content in the particle-containing layer is preferably 0.1% to 30% by mass, more preferably 1% to 25% by mass, and even more preferably 1% to 15% by mass, relative to the total mass of the particle-containing layer. Furthermore, the particle content is preferably 0.0001% to 0.01% by mass, and more preferably 0.0005% to 0.005% by mass, relative to the total mass of the release film.

[0088] (Non-polyester resin (binder)) The particle-containing layer preferably contains a non-polyester resin. The non-polyester resin contained in the particle-containing layer functions as a binder.

[0089] Non-polyester resins refer to resins other than polyester resins. Specifically, non-polyester resins are preferably at least one selected from the group consisting of acrylic resins, urethane resins, olefin resins, polyvinyl alcohol resins, styrene-butadiene resins, and acrylonitrile-butadiene resins, and are preferably at least one resin selected from the group consisting of acrylic resins, urethane resins, and olefin resins, in order to obtain superior effects from this disclosure.

[0090] Here, the solubility parameters (SP values) of non-polyester resins (especially acrylic resins, urethane resins, and olefin resins) and polyester resins are far apart. In other words, the compatibility between acrylic resins, urethane resins, and olefin resins and polyester resins is insufficient, making it difficult for impurities such as oligomers to precipitate from the polyester substrate through the particle-containing layer onto the transport surface. As a result, it is presumed that protrusions caused by impurities contained in the polyester substrate are less likely to form on the transport surface.

[0091] The above-mentioned acrylic resin, urethane resin, and non-polyester resin such as olefin resin are not particularly limited, and known resins can be used. The non-polyester resin is preferably an acid group-containing non-polyester resin. Furthermore, the particle-containing layer may also contain polyester resin.

[0092] Acrylic resin is a resin containing structural units derived from (meth)acrylate, and may be copolymerized with vinyl monomers such as styrene. The acrylic resin is not particularly limited, but it is preferable to contain structural units derived from (meth)acrylate having alkyl groups having 1 to 12 carbon atoms, and more preferable to contain structural units derived from (meth)acrylate having alkyl groups having 1 to 8 carbon atoms. The acrylic resin may contain an acid-modified component. The acrylic resin may contain constituent units derived from (meth)acrylic acid as the acid-modified component. Furthermore, (meth)acrylic acid may form an acid anhydride or be neutralized with at least one selected from alkali metals, organic amines, and ammonia.

[0093] The acid value of the acrylic resin is preferably 30 mg KOH / g or less, and more preferably 20 mg KOH / g or less. The lower limit of the acid value is not particularly limited, for example, 0 mg KOH / g, but from the perspective of coating as an aqueous dispersion, 2 mg KOH / g or more is preferred. By setting the acid value of the acrylic resin within the above range and / or including constituent units derived from (meth)acrylate having alkyl groups with 1 to 12 carbon atoms, it is possible to make the resin even less compatible with polyester resin, thereby further suppressing the precipitation of impurities such as oligomers contained in the polyester substrate into the particle-containing layer, and further suppressing defects in the ceramic green sheet.

[0094] The olefin resin can be any resin that contains structural units derived from olefins in its main chain. By having structural units derived from olefins in its main chain, it is possible to create a resin that is poorly compatible with polyester resins, which suppresses the precipitation of impurities such as oligomers contained in the polyester substrate into the particle-containing layer, thereby suppressing defects in the ceramic green sheet. 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 in the polyolefin are preferably 50 mol% to 99 mol%, and more preferably 60 mol% to 98 mol%, relative to all structural units of the polyolefin.

[0095] As the olefin resin, an acid group-containing olefin resin is preferred. Examples of acid group-containing olefin resins include those similar to the acid group-containing olefin resins that may be included in the above-mentioned release layer-forming composition.

[0096] The urethane resin is not limited as long as it is a polymer having urethane bonds in its main chain, and known urethane resins such as reaction products of polyisocyanate compounds and polyol compounds can be used. In terms of ease of film formation by coating, the urethane resin is preferably an acid group-containing urethane resin, or a form containing urethane resin and a dispersant. Specific examples of acid groups are as described above. For example, by adjusting the structure and hydrophobicity (hydrophilicity) of the polyol compound and isocyanate compound used as raw materials, the urethane resin can be made less compatible with polyester resin. This suppresses the precipitation of impurities such as oligomers contained in the polyester substrate into the particle-containing layer, thereby suppressing defects in the ceramic green sheet. It is preferable that the urethane resin contains a polyester structure in order to further improve defect suppression. Examples of acid group-containing urethane resins include those similar to the acid group-containing urethane resins that may be included in the above-mentioned release layer-forming composition.

[0097] The non-polyester resin contained in the particle-containing layer may have a cross-linked structure. In other words, the particle-containing layer may be a cross-linked film. To form a non-polyester resin having a crosslinked structure, one method is to form a particle-containing layer using a particle-containing layer-forming composition containing a crosslinking agent, as described later.

[0098] The particle-containing layer may contain one type of binder or two or more types of binders. Furthermore, the particle-containing layer may contain one type of non-polyester resin or two or more types of non-polyester resins. From the viewpoint of suppressing defects, the binder (preferably a non-polyester resin) content is preferably 30% to 99.8% by mass, and more preferably 50% to 99.5% by mass, relative to the total mass of the particle-containing layer.

[0099] (Additives) The particle-containing layer may contain additives other than the above-mentioned particles and binder. Examples of additives included in the particle-containing layer include surfactants, waxes, antioxidants, UV absorbers, colorants, strengthening agents, plasticizers, antistatic agents, flame retardants, rust inhibitors, and mold inhibitors.

[0100] The particle-containing layer preferably contains a surfactant, as this improves the smoothness of areas on the transport surface other than those where protrusions formed by the particles exist. The surfactant is not particularly limited and includes silicone-based surfactants, fluorine-based surfactants, and hydrocarbon-based surfactants. Among these, hydrocarbon-based surfactants are preferred.

[0101] The silicone-based surfactant is not particularly limited as long as it is a surfactant having a silicon-containing group as a hydrophobic group, and examples include polydimethylsiloxane, polyether-modified polydimethylsiloxane, and polymethylalkylsiloxane. Examples of commercially available silicone-based surfactants include BYK(registered trademark)-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-347, BYK-348, and BYK-349 (all manufactured by BYK), as well as KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF-642, KF-643, KF-6020, X-22-4515, KF-6011, KF-6012, KF-6015, and KF-6017 (all manufactured by Shin-Etsu Chemical Co., Ltd.).

[0102] The fluorinated surfactant is not particularly limited as long as it is a surfactant having a fluorine-containing group as a hydrophobic group, and examples include perfluorooctanesulfonic acid and perfluorocarboxylic acid. Examples of commercially available fluorine-based surfactants include Megafac® F-114, F-410, F-440, F-447, F-553, and F-556 (all manufactured by DIC Corporation), and Surflon® 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.). Furthermore, as a fluorine-based surfactant, from the viewpoint of improving environmental suitability, it is preferable to use a surfactant derived from a substitute material for a compound having a linear perfluoroalkyl group with 7 or more carbon atoms, such as perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS).

[0103] Examples of hydrocarbon-based surfactants include anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. Examples of anionic surfactants include alkyl sulfates, alkylbenzene sulfons, alkyl phosphates, and fatty acid salts. Examples of nonionic surfactants include polyalkylene glycol mono- or dialkyl ethers, polyalkylene glycol mono- or dialkyl esters, and polyalkylene glycol monoalkyl esters / monoalkyl ethers. Examples of cationic surfactants include primary to tertiary alkylamine salts and quaternary ammonium compounds. Examples of amphoteric surfactants include surfactants that have both anionic and cationic sites within their molecule.

[0104] Examples of commercially available anionic surfactants include Rapizole® A-90, A-80, BW-30, B-90, and C-70 (all manufactured by NOF Corporation), Nikkol® OTP-100 (all manufactured by Nikko Chemical Co., Ltd.), Kohacool® ON, L-40, and Phosphanol® 702 (all manufactured by Toho Chemical Industry Co., Ltd.), and Viewlight® A-5000 and SSS (all manufactured by Sanyo Chemical Industries, Ltd.). Examples of commercially available nonionic surfactants include Naroacty® CL-95 and HN-100 (product name: manufactured by Sanyo Chemical Industries, Ltd.), Risolex BW400 (product name: manufactured by Kofu Alcohol Industry Co., Ltd.), EMALEX® ET-2020 (all manufactured by Nippon Emulsion Co., Ltd.), and Surfinol® 104E, 420, 440, 465, and Dynol® 604, 607 (all manufactured by Nisshin Chemical Industry Co., Ltd.).

[0105] Among hydrocarbon-based surfactants, anionic surfactants and / or nonionic surfactants are preferred, and anionic surfactants are more preferred.

[0106] Anionic hydrocarbon surfactants are preferable to have multiple hydrophobic end groups in that they have improved smoothness. The hydrophobic end groups may be some of the hydrocarbon groups that the hydrocarbon surfactant has. For example, a hydrocarbon surfactant having a branched-chain hydrocarbon group at its end will have multiple hydrophobic end groups. Examples of anionic hydrocarbon surfactants having multiple hydrophobic end groups include sodium di-2-ethylhexyl sulfosuccinate (having four hydrophobic end groups), sodium di-2-ethyloctyl sulfosuccinate (having four hydrophobic end groups), and branched-chain alkylbenzene sulfonates (having two hydrophobic end groups).

[0107] One type of surfactant may be used, or two or more types may be used in combination. If the particle-containing layer contains a surfactant, the surfactant content is preferably 0.1% to 10% by mass relative to the total mass of the particle-containing layer, more preferably 0.1% to 5% by mass, and even more preferably 0.5% to 2% by mass, in terms of superior surface smoothness.

[0108] The wax is not particularly limited and may be either natural or synthetic. Examples of natural waxes include carnauba wax, candelilla wax, beeswax, montan wax, paraffin wax, and petroleum wax. In addition, the lubricants described in section

[0087] of International Publication No. 2017 / 169844 may also be used. The wax content is preferably 0% to 10% by mass relative to the total mass of the particle-containing layer.

[0109] [Properties of the particle-containing layer] (Thickness) When a particle-containing layer is formed, for example, by coating a composition containing particles and a non-polyester resin onto one surface of a polyester film, the thickness of the particle-containing layer is often 1 μm or less. Furthermore, when a polyester film with a particle-containing layer is formed by co-extrusion molding, the thickness of the particle-containing layer is often between 1 μm and 10 μm. The thickness of the particle-containing layer is preferably 1 nm to 3 μm. When manufactured by coating, from the viewpoint of manufacturability and haze reduction, it is preferably 1 nm to 500 nm, more preferably 1 nm to 250 nm, even more preferably 10 nm to 100 nm, and particularly preferably 20 nm to 100 nm. The thickness of the particle-containing layer is determined by preparing a section of the release film with a cross-section perpendicular to the main surface, and measuring the thickness at five points on the section using a scanning electron microscope (SEM) or transmission electron microscope (TEM), and taking the arithmetic mean of the thicknesses of these sections.

[0110] <Properties of the 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 superior release properties. Furthermore, the thickness of the release film is preferably 3 μm or more, more preferably 10 μm or more, and even more preferably 20 μm or more, in terms of improved strength and processability. The thickness of the release film shall be measured using a continuous stylus-type film thickness gauge. Specifically, measurements shall be taken at five different locations. The arithmetic mean of the obtained measurements shall be taken as the thickness.

[0111] [Method for manufacturing release film] A method for manufacturing the release film described herein will be explained. The method for manufacturing the release film described herein is not particularly limited as long as the above-described release film is obtained, and known methods can be used.

[0112] For example, the method for manufacturing a release film according to the present disclosure is a method for manufacturing a release film comprising a polyester substrate and a release layer, and includes the step of forming a release layer using a release layer forming composition containing a silicone compound and a carbodiimide compound.

[0113] In particular, a preferred method for manufacturing release films, in terms of being able to produce release films with high productivity, is: An extrusion molding process to form an unstretched polyester film by extrusion molding, The stretching process includes a first stretching step in which an unstretched polyester film is stretched in either the conveying direction or the width direction to form a uniaxially stretched polyester film, and a second stretching step in which the uniaxially stretched polyester film is stretched in the other direction, the conveying direction or the width direction to form a biaxially stretched polyester film, performed either in stages or simultaneously. A manufacturing method is provided which includes a release layer formation step, performed between the extrusion molding step and the stretching step, between the first stretching step and the second stretching step, or after the stretching step, in which a release layer forming composition is applied to one surface of the polyester film to form a release layer.

[0114] The above manufacturing method yields a release film comprising a polyester substrate and a release layer. Specifically, the polyester substrate is preferably an unstretched polyester film that has been stretched in both the transport direction and the width direction.

[0115] Furthermore, the method for manufacturing the release film of this disclosure may further include a particle-containing layer forming step, which involves applying a particle-containing layer forming composition 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, to form a particle-containing layer.

[0116] The above manufacturing method yields a release film comprising a polyester substrate, a release layer disposed on one surface of the polyester substrate, and a particle-containing layer disposed on the surface of the polyester substrate opposite to the side on which the release layer is located.

[0117] The following describes each step in a preferred embodiment of the manufacturing method of the present disclosure. However, the manufacturing method of the present disclosure is not limited to this preferred embodiment, and the following steps may be omitted as appropriate.

[0118] [Extrusion molding process] The extrusion molding process is a process in which an unstretched polyester film is formed by extrusion molding. More specifically, this process involves extruding a molten resin containing the raw polyester resin into a film to form an unstretched polyester film. The raw polyester resin is the same as the polyester resin described in the (Polyester Resin) section above. Furthermore, in order to produce a polyester film that is substantially free of particles, it is preferable to use particle-free polyester pellets during the extrusion molding process.

[0119] Extrusion molding is a method of molding raw material resin into a desired shape by, for example, using an extruder to push out a molten raw material resin. The molten material extruded from the extrusion die is formed into a film by cooling. For example, the molten material can be formed into a film by bringing it into contact with a casting roll and cooling and solidifying it on the casting roll. In cooling the molten material, it is preferable to further apply air (preferably cold air) to the molten material.

[0120] [Stretching process] The stretching process is a process that involves performing, either in stages or simultaneously, a first stretching process in which an unstretched polyester film is stretched in either the conveying direction or the width direction to form a uniaxially stretched polyester film, and a second stretching process in which the uniaxially stretched polyester film is stretched in the other direction (conveying direction or width direction) to form a biaxially stretched polyester film. One of the first and second stretching steps is a longitudinal stretching step in which the polyester film is stretched in the transport direction (hereinafter also referred to as "longitudinal stretching"), and the other of the first and second stretching steps is a transverse stretching step in which the polyester film is stretched in the width direction (hereinafter also referred to as "transverse stretching"). During stretching, the polyester polymers are arranged in each respective direction.

[0121] The stretching process described above may be simultaneous biaxial stretching, in which longitudinal stretching and transverse stretching are performed at the same time, or it may be sequential biaxial stretching, in which longitudinal stretching and transverse stretching are performed in stages. Examples of sequential biaxial stretching include stretching in the order of longitudinal stretching followed by transverse stretching; stretching in the order of longitudinal stretching, transverse stretching, and longitudinal stretching; and stretching in the order of longitudinal stretching, longitudinal stretching, and transverse stretching. Among these, the sequential biaxial stretching method in which the stretching is performed in the order of longitudinal stretching followed by transverse stretching is preferred. The following describes a method in which the stretching is performed in the order of longitudinal stretching followed by transverse stretching, but the above manufacturing method is not limited to this method.

[0122] The stretching ratio in the longitudinal stretching process is set as appropriate, but is preferably 2.0 to 5.0 times, more preferably 2.5 to 4.0 times, and even more preferably 2.8 to 4.0 times. The stretching speed in the longitudinal stretching process is preferably 800% / second to 1500% / second, more preferably 1000% / second to 1400% / second, and even more preferably 1200% / second to 1400% / second. Here, "stretching speed" is the value obtained by dividing the length Δd of the polyester film stretched in the transport direction per second in the longitudinal stretching process by the length d0 of the polyester film before stretching in the transport direction, expressed as a percentage. In the longitudinal stretching process, it is preferable to heat the unstretched polyester film. This is because heating facilitates longitudinal stretching.

[0123] In the transverse stretching process, it is preferable to preheat the uniaxially stretched polyester film before transverse stretching. Preheating the uniaxially stretched polyester substrate allows for easy transverse stretching. The stretching ratio in the width direction (transverse stretching ratio) of the uniaxially stretched polyester film in the transverse stretching process is not particularly limited, but it is preferable that it is greater than the stretching ratio in the longitudinal stretching process described above. The stretching ratio in the transverse stretching process is preferably 3.0 to 6.0 times, more preferably 3.5 to 5.0 times, and even more preferably 3.5 to 4.5 times. The stretching speed in the transverse stretching process is preferably 8% / second to 45% / second, more preferably 10% / second to 30% / second, and even more preferably 15% / second to 20% / second.

[0124] [Particle-containing layer formation process] The particle-containing layer formation process involves applying a particle-containing layer formation composition to one surface of a polyester film to form a particle-containing layer. The particle-containing layer formation 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. Preferably, the particle-containing layer formation step is performed between the first stretching step and the second stretching step. The particle-containing layer that is placed on one surface of the polyester substrate by the particle-containing layer formation step is the same as the layer described in the section on particle-containing layers above. The following describes embodiments for providing the particle-containing layer-forming composition.

[0125] First, we will describe the composition for forming a particle-containing layer. A composition for forming a particle-containing layer can be prepared by mixing the components described in the section on particle-containing layers and a solvent. Examples of solvents include water and alcohol.

[0126] The particle-containing layer-forming composition may contain one solvent or two or more solvents. The solvent content is preferably 80% to 99.5% by mass, and more preferably 90% to 99% by mass, based on the total mass of the particle-containing layer-forming composition. In other words, in the particle-containing layer-forming composition, the total content of components other than the solvent (solids) is preferably 0.5% to 20% by mass, and more preferably 1% to 10% by mass, relative to the total mass of the particle-containing layer-forming composition.

[0127] With respect to each component other than the solvent in the particle-containing layer-forming composition, it is preferable to adjust the content of each component in the particle-containing layer-forming composition so that the content of each component relative to the total mass of solids in the particle-containing layer-forming composition is the same as the preferred content of each component relative to the total mass of the particle-containing layer.

[0128] Furthermore, the particle-containing layer-forming composition may also contain a crosslinking agent. Examples of crosslinking agents include the above-mentioned carbodiimide compounds and other crosslinking agents. The crosslinking agent content is preferably 0% to 50% by mass relative to the total mass of the particle-containing layer. In a particle-containing layer-forming composition, the preferred mass ratio of the crosslinking agent to the binder is 2% to 50% by mass.

[0129] The method for applying the particle-containing layer-forming composition is not particularly limited, and known methods can be used. Examples of application methods include spray coating, slit coating, roll coating, blade coating, spin coating, bar coating, and dip coating.

[0130] The heating temperature for forming the particle-containing layer is preferably 180°C or lower, more preferably 150°C or lower, and even more preferably 120°C or lower. The lower limit is not particularly limited and may be 60°C or higher.

[0131] Furthermore, in order to improve the adhesion between the polyester film and the particle-containing layer, the surface of the polyester film may be pre-treated with an anchor coat, corona treatment, or plasma treatment before the particle-containing layer is applied.

[0132] [Exfoliation layer formation process] The release layer formation process involves applying a release layer formation composition to a polyester film to form a release layer. The release layer formation process is performed between the extrusion molding process and the first stretching process, between the first stretching process and the second stretching process, or after the stretching process.

[0133] In particular, from the viewpoint of adhesion between the release layer and the polyester substrate, it is preferable that the release layer formation process be carried out between the extrusion molding process and the first stretching process, or between the first stretching process and the second stretching process. In other words, 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.

[0134] When the peeling layer formation process is performed after the stretching process, it is preferable to perform it after the cooling process described later, and more preferably after the winding process and trimming process described later. The release layer formed on the surface of the polyester film by the release layer formation process is the same as the layer described in the section on release layers above.

[0135] First, we will describe the composition for forming the release layer. The composition for forming the release layer preferably contains the components described in the section on the release layer above, as well as a solvent. Examples of solvents include water, alcohols, ethers, ketones, and aromatic hydrocarbons.

[0136] The release layer forming composition may contain one solvent or two or more solvents. The solvent content is preferably 80% to 99.5% by mass, and more preferably 90% to 99% by mass, based on the total mass of the release layer forming composition. In other words, in the release layer forming composition, the total content of components other than the solvent (solids) is preferably 0.5% to 20% by mass, and more preferably 1% to 10% by mass, based on the total mass of the release layer forming composition.

[0137] With respect to each component other than the solvent in the release layer forming composition, it is preferable to adjust the content of each component in the release layer forming composition so that the content of each component relative to the total mass of solids in the release layer forming composition is the same as the preferred content of each component relative to the total mass of the release layer.

[0138] The method for applying the release layer-forming composition is not particularly limited, and known methods can be used. Specific examples of application methods are described in the particle-containing layer formation step.

[0139] The heating temperature for forming the release layer is preferably 180°C or lower, more preferably 150°C or lower, and even more preferably 120°C or lower. The lower limit is not particularly limited and may be 60°C or higher.

[0140] Furthermore, in order to improve the adhesion between the polyester film and the release layer, pretreatment such as anchor coating, corona treatment, and plasma treatment may be applied to the surface of the polyester film before applying the release layer.

[0141] [Heat setting process] The above method for manufacturing the release film may include a heat-setting step as a heat treatment for the polyester film obtained in the stretching step, after the stretching step. In the heat-setting process, the polyester film obtained in the stretching process can be heated and heat-set. By crystallizing the polyester resin through heat-setting, shrinkage of the polyester substrate can be suppressed. The surface temperature of the polyester film in the heat-setting process (heat-setting temperature) 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. The lower limit is not particularly limited, but is preferably 190°C or higher, more preferably 200°C or higher, and even more preferably 210°C or higher. The heating time in the heat setting process is preferably 5 to 50 seconds, more preferably 5 to 30 seconds, and even more preferably 5 to 10 seconds.

[0142] [Thermal relaxation process] The method for manufacturing the release film of this disclosure may include a heat relaxation step after the heat setting step. In the thermal relaxation process, it is preferable to thermally relax the polyester film, which has been thermally fixed in the thermal fixing process, by heating it at a lower temperature than that of the thermal fixing process. Thermal relaxation can alleviate residual strain in the polyester film. In the heat relaxation process, the surface temperature of the polyester film (heat relaxation temperature) is preferably 5°C or more lower than the heat fixing temperature, more preferably 15°C or more lower, even more preferably 25°C or more lower, and particularly preferably 30°C or more lower. That is, the heat 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.

[0143] [Cooling process] The method for manufacturing the release film of this disclosure may include a cooling step of cooling the heat-relaxed polyester film. The cooling rate of the polyester film in the cooling process is preferably more than 2000°C / min and less than 4000°C / min, more preferably between 2000°C / min and 3500°C / min, even more preferably more than 2200°C / min and less than 3000°C / min, and particularly preferably between 2300°C / min and 2800°C / min. In the above cooling process, it is also preferable to include a step (expansion step) of expanding the heat-relaxed polyester film in the width direction. The expansion rate in the width direction of the polyester film due to the expansion process, that is, the ratio of the polyester film width at the end of the cooling process to the polyester film width before the start of the cooling process, is preferably 0% or more, more preferably 0.001% or more, and even more preferably 0.01% or more. There is no particular upper limit to the expansion rate, but it is preferably 1.3% or less, more preferably 1.2% or less, and even more preferably 1.0% or less.

[0144] [Winding process] The method for manufacturing the release film of this disclosure may include a winding step to obtain a roll of polyester film by winding up the polyester film obtained through the above steps.

[0145] [Trimming process] The manufacturing method of the present disclosure may include a trimming step, before performing the winding step, in which the polyester film is continuously cut along the transport direction to cut off at least one end of the polyester film in the width direction.

[0146] [Other conditions] The conveying speed of the polyester film in each step of the method for manufacturing the release film of this disclosure, other than the longitudinal stretching step, is not particularly limited, but in the transverse stretching step, heat setting step, heat relaxation step, and cooling step, 50 m / min to 200 m / min is preferred, and 80 m / min to 150 m / min is more preferred in terms of productivity and quality.

[0147] In the above manufacturing method, a method for forming a particle-containing layer by applying a particle-containing layer-forming composition in the particle-containing layer formation step has been described. However, the method for forming the particle-containing layer is not limited to the above embodiment, and known methods can be used. For example, one method is to form an unstretched polyester film with laminated particle-containing layers by co-extrusion molding.

[0148] In particular, the method for manufacturing the release film of this disclosure is A longitudinal stretching process in which an unstretched polyester film is stretched in the transport direction, A step of forming a particle-containing layer by applying a particle-containing layer-forming composition to one side of a uniaxially stretched polyester film obtained in a longitudinal stretching step, A step of forming a release layer on the other side of a uniaxially stretched polyester film obtained in a longitudinal stretching step, Preferably, the process includes a transverse stretching step in which a uniaxially stretched polyester film having a particle-containing layer and a release layer is stretched in the width direction while being heated.

[0149] [Uses of release film] The release film is preferably a release film (carrier film) used in the manufacture of ceramic green sheets. The ceramic green sheet manufactured using the above-mentioned release film can be suitably used in the manufacture of ceramic capacitors, where multilayering of internal electrodes is required due to miniaturization and increased capacitance.

[0150] Furthermore, the release film of this disclosure can also be used as a protective film for dry film resists, a film for sheet molding such as decorative layers and resin sheets, a release film for process manufacturing such as semiconductor manufacturing processes, a release film for polarizing plate manufacturing processes, and a separator for adhesive films such as labels, medical and office supplies.

[0151] [Laminate] The laminate of this disclosure includes the release film and a ceramic-containing layer disposed on the release film.

[0152] 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 it 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 in terms of superior smoothness.

[0153] Examples of ceramic powders included in the ceramic-containing layer include ferroelectric materials such as barium titanate, and paraelectric materials such as titanium oxide and calcium titanate.

[0154] The ceramic-containing layer preferably contains a binder. The binder is not particularly limited and, for example, polyvinyl butyral.

[0155] The laminate of this disclosure can be manufactured, for example, by applying a ceramic slurry containing ceramics and a solvent to the release surface of a release film, and drying the solvent contained in the ceramic slurry. Examples of solvents include ethanol and toluene.

[0156] The method for applying the ceramic slurry is not particularly limited, and known methods such as the reverse roll method can be applied. [Examples]

[0157] The present disclosure will be further described with reference to the following examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples may be modified as appropriate, as long as they do not deviate from the spirit of the present disclosure. Accordingly, the scope of the present disclosure is not limited to the following specific examples.

[0158] <Example 1> (Extrusion molding process) A titanium compound (titanium citrate chelate complex, VERTEC AC-420, manufactured by Johnson Matthey) described in Japanese Patent No. 5575671 was used as a polymerization catalyst to produce polyethylene terephthalate pellets. The obtained pellets were dried until the moisture content was 50 ppm or less, and then fed into the hopper of a twin-screw compounding extruder. Next, they were melted at 280°C and extruded. The molten material was passed through a filter (pore size 3 μm) and then extruded from the die into a cooling drum at 25°C to obtain a film made of unstretched polyethylene terephthalate (unstretched film). The extruded molten material was then brought into close contact with the cooling drum by electrostatic application.

[0159] (Longitudinal stretching process) Uniaxially stretched polyester film was produced by stretching the above unstretched film in the longitudinal direction (conveying direction) under conditions of 90°C and 3.4 times its original length.

[0160] (Particle-containing layer formation process, peel-off layer formation process) A particle-containing layer-forming composition A1, as shown below, was applied to one side of a uniaxially stretched polyester film using a bar coater. A release layer-forming composition L1, as shown below, was applied to the side of the uniaxially stretched polyester film opposite to the side coated with the particle-containing layer using a bar coater. The formed coating film was dried with hot air at 100°C to form a particle-containing layer and a release layer. In other words, the particle-containing layer-forming composition A1 and the release layer-forming composition L1 were in-line coated onto a uniaxially stretched polyester film. At this time, the amount of particle-containing layer-forming composition A1 and the release layer-forming composition L1 applied was adjusted so that the thickness of the particle-containing layer after transverse stretching, as described later, would be 40 nm and the thickness of the release layer would be 100 nm.

[0161] A polyester film that had undergone longitudinal stretching, release layer formation, and particle-containing layer formation processes was stretched in the width direction using a tenter under the conditions of a stretching temperature of 120°C, a stretching ratio of 4.2 times, and a stretching speed of 50% / second to produce a biaxially stretched polyester film. Next, it was heat-set at 227°C for 6 seconds, and then heat-relaxed by 4% at 190°C. After that, it was cooled at a rate of 2500°C / min, trimmed at both ends of the film, extruded (knurled), and then wound up with a tension of 40 kg / m. The resulting release film had a thickness of 31 μm, a width of 1.5 m, and a winding length of 7000 m.

[0162] [Preparation of Composition L1 for Forming the Release Layer] • Silicone compound: Silicone A (product name "X-22-3701E", manufactured by Shin-Etsu Chemical Co., Ltd., a silicone compound containing a carboxyl group, 10% by mass solid content diluted with water) ... 80 parts by mass • Carbodiimide compound: Carbodiimide A (product name "Carbodilite V-02-L2", carbodiimide equivalent 385, manufactured by Nisshinbo Chemical Co., Ltd., 10% by mass diluted solution) ... 62.8 parts by mass • Acid group-containing non-silicone resin: Urethane resin A (product name "Arrowbase SE1010", manufactured by Unitika Ltd., solid content concentration 25% by mass aqueous dispersion) ... 100.6 parts by mass • Surfactant A (product name "Naroacty CL95", manufactured by Sanyo Chemical Industries, Ltd., nonionic surfactant, 1% by mass aqueous solution) ... 32 parts by mass • Surfactant B (product name "Rapizol (registered trademark) A-90", sodium di-2-ethylhexyl sulfosuccinate, manufactured by NOF Corporation, solid content concentration 1% by mass, diluted with water) ... 24 parts by mass • Distilled water…700 parts

[0163] [Preparation of composition A1 for forming a particle-containing layer] • Cross-linked PMMA particles (Epostor® MX050W, manufactured by Nippon Shokubai Co., Ltd., average particle size 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", sodium di-2-ethylhexyl sulfosuccinate, manufactured by NOF Corporation, solid content concentration 1% by mass, diluted with water) ... 56 parts by mass ·Water…779 parts by mass

[0164] <Examples 2-20, Comparative Example 1> A release film was prepared in the same manner as in Example 1, except that the type and content (mass%) of each component in the release layer forming composition were changed to those listed in Table 1, and the type of resin in the particle-containing layer forming composition was also changed to those listed in Table 1.

[0165] <Comparative Example 2 to Comparative Example 3> A release film was prepared in the same manner as in Example 1, except that the type and content (mass%) of each component in the release layer forming composition were changed to those shown in Table 1, and a corona treatment was applied to the surface of a uniaxially stretched polyester film before applying the release layer forming composition, without providing a particle-containing layer.

[0166] The details of each component listed in Table 1 are as follows:

[0167] (Silicone compounds) • Silicone A: Silicone compound containing a carboxyl 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: A mixture obtained by mixing product name "X-62-7655" (a coating agent containing silicone components, manufactured by Shin-Etsu Chemical Co., Ltd.), product name "X-62-7622" (a coating agent containing silicone components, manufactured by Shin-Etsu Chemical Co., Ltd.), and product name "CAT-7605" (a catalyst, manufactured by Shin-Etsu Chemical Co., Ltd.) in a mass ratio of 95:5:1.

[0168] (Crosslinking agent) • Carbodiimide A: Carbodiimide compound (product name "Carbodilite V-02-L2", carbodiimide equivalent 385, manufactured by Nisshinbo Chemical Co., Ltd.) • Carbodiimide B: Carbodiimide compound (product name "Carbodilite V-02", carbodiimide equivalent 590, manufactured by Nisshinbo Chemical Co., Ltd.) • Carbodiimide B: Carbodiimide compound (product name "Carbodilite V-04", carbodiimide equivalent 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 Chemical Industry Co., Ltd.)

[0169] (Non-silicone resin) • Urethane resin A: Product name "Arrowbase SE1010", manufactured by Unitika 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 "Zyxen (registered trademark) NC", manufactured by Sumitomo Seika Co., Ltd. • Polyester resin: Product name "Vaironal MD1245", manufactured by Toyobo Co., Ltd. • Acrylic resin: Acrylic resin prepared by the method described below • Long-chain alkyl group-containing resins: Long-chain alkyl group-containing resins prepared according to the method described in

[0122] of International Publication No. 2020 / 017289

[0170] -Preparation of acrylic resin- In a three-necked flask, methyl methacrylate, hydroxyethyl methacrylate, and urethane acrylate oligomer (product name "Artresin (registered trademark) UN-3320HA," manufactured by Negami Kogyo Co., Ltd., with 6 acryloyl groups) were charged in a mass ratio of 94 / 1 / 5. Sodium dodecylbenzenesulfonate was added at a ratio of 2 parts by mass to 100 parts by mass of the total monomers to obtain a monomer solution. In a separate reaction vessel, 60 parts by mass of the monomer solution, 200 parts by mass of isopropyl alcohol, and 5 parts by mass of potassium persulfate were added, and the mixture was heated to 60°C and stirred for 20 minutes to obtain mixture A. Next, a mixture consisting of 40 parts by mass of the monomer solution, 50 parts by mass of isopropyl alcohol, and 5 parts by mass of potassium persulfate was prepared and added dropwise to mixture A over 2 hours using a dropping funnel. After the dropwise addition was complete, the mixture was allowed to react for 2 hours while remaining heated at 60°C. After cooling the resulting reaction solution to 25°C, 60 parts by mass of 25% ammonia water and 900 parts by mass of pure water were added. The isopropyl alcohol and unreacted monomers were then removed by distillation under reduced pressure while heating to 60°C to obtain an aqueous dispersion of acrylic resin.

[0171] (Surfactants) • Surfactant A: Product name "Naroacty CL95", manufactured by Sanyo Chemical Industries, Ltd. • Surfactant B: Product name "Rapizol (registered trademark) A-90", manufactured by NOF Corporation • Surfactant C: Product name "Pluscoat RY-2", manufactured by Go-o Chemical Industry Co., Ltd.

[0172] The prepared release films were evaluated for release properties, solvent resistance, and defects. The evaluation method was as follows:

[0173] <Removability> 100 parts by mass of barium titanate powder (BaTiO3; manufactured by Sakai Chemical Industry Co., Ltd., product name "BT-03") as a ceramic powder, 8 parts by mass of polyvinyl butyral resin (product name "Eslec® B·K BM-2", manufactured by Sekisui Chemical Co., Ltd.) as a binder, 4 parts by mass of dioctyl phthalate (product name "Dioctyl Phthalate Grade 1", manufactured by Kanto Chemical Co., Ltd.) as a plasticizer, and 135 parts by mass of a mixture of toluene and ethanol (mass ratio 6:4) were mixed. The mixture was dispersed using a ball mill in the presence of zirconia beads, and a ceramic slurry was prepared by removing the beads from the resulting dispersion. The release films prepared in the examples and comparative examples were cut to a width of 250 mm and a length of 10 m. The cut release films were stored for one week in a normal temperature and humidity environment (25°C, 50% RH). After storage, the prepared ceramic slurry was coated onto the entire release surface of the release films using a die coater so that the film thickness after drying was 3 μm. The resulting coating was then dried in a dryer at 100°C for 2 minutes. This yielded release films with a ceramic green sheet. A polyester adhesive tape (model number "No. 31B", manufactured by Nitto Denko Corporation) was attached to the surface of the ceramic green sheet in a release film with a ceramic green sheet. After standing at room temperature (25°C) for 24 hours, the release film with the ceramic green sheet was cut to a width of 20 mm to prepare test samples. The adhesive tape side of the test sample was fixed to the surface of a glass plate, and the release film was peeled from the release film with the ceramic green sheet using an A&D Tensilon universal tester under the conditions of a peel angle of 180° and a peel speed of 100 mm / min, and the force required for peeling was measured. The peelability was evaluated based on the force required for peeling. The evaluation criteria are as follows. A: The force required for peeling was 45 mN or less. B: The force required for peeling was between 45 mN and 100 mN. C: The force required for peeling was over 100 mN.

[0174] <Solvent resistance> For the release films prepared in the examples and comparative examples, a cloth soaked in a mixed solution of methyl ethyl ketone and toluene (mass ratio 1:1) was used to apply a load of 500 g / cm² to the surface of the release layer. 2 The surface was polished five times vertically and five times horizontally. Afterwards, the surface of the peeled layer was visually observed, and the solvent resistance was evaluated based on the dissolution state of the peeled layer. The evaluation criteria are as follows: A: The exfoliated layer has not dissolved at all. B: Part of the peeled layer has dissolved. C: The peeled layer has completely dissolved.

[0175] <Defect Assessment> The release films obtained in each example and comparative example were stored for 3 months in a normal temperature and humidity environment. Using the release films stored for 3 months, a release film with a ceramic green sheet was obtained in the same manner as the method used for evaluating release properties, except that the amount of ceramic slurry applied was adjusted so that the film thickness after drying of the ceramic slurry was 1 μm. After being wound into a roll, a fluorescent lamp was shone from the release film side of the unwound ceramic green sheet release film, and the surface of the ceramic green sheet was measured at 1 m 2 The area was visually inspected to check for the presence of minute irregularities such as pinholes. The defects were evaluated based on the number of defects found. The evaluation criteria are as follows: A: No irregularities or defects were found in the ceramic green sheet. B: One to ten irregularities were found in the ceramic green sheet. C: More than 11 irregularities were found in the ceramic green sheet.

[0176] Furthermore, when the release films obtained from each example and comparative example were evaluated for defects using the same method as described above, without being stored for three months, the evaluation result was A in all cases.

[0177] The evaluation results are shown in Table 1. In Table 1, the column for the release layer lists the type and content (mass%) of each component contained in the release layer forming composition. The content refers to the solid content of each component. The column for the particle-containing layer lists the type of resin contained in the particle-containing layer forming composition. If the silicone compound contains acidic groups, "Y" is indicated; if it does not contain acidic groups, "N" is indicated. Non-silicone resins refer to resins other than silicone resins; if they contain acidic groups, "Y" is indicated; if they do not contain acidic groups, "N" is indicated. Furthermore, "acidic group-containing non-silicone resin / silicone compound" refers to the mass ratio of the acidic group-containing non-silicone resin content to the silicone compound content. "Silicone compound / carbodiimide compound" refers to the mass ratio of the silicone compound content to the carbodiimide compound content.

[0178] [Table 1]

[0179] The release films of Examples 1 to 20 comprise a polyester substrate and a release layer, and the release layer is formed by crosslinking a composition containing a silicone compound and a carbodiimide compound, and satisfy at least one of conditions 1 and 2, so it was found to have excellent release properties and solvent resistance.

[0180] On the other hand, it was found that the release films of Comparative Example 1 and Comparative Example 2 did not contain a silicone compound in the release layer forming composition and therefore had poor release properties.

[0181] The release film of Comparative Example 3 was found to have poor solvent resistance because the release layer-forming composition did not contain a carbodiimide compound.

[0182] Examples 14 to 17 showed that when the mass ratio of the acid group-containing non-silicone resin to the silicone compound content in the release layer-forming composition is 1 to 30, the release properties and solvent resistance are superior.

[0183] In Example 16, the mass ratio of the silicone compound to the carbodiimide compound in the release layer forming composition was 0.1 or higher, resulting in superior solvent resistance compared to Example 17. In Example 14, the mass ratio of the silicone compound to the carbodiimide compound in the release layer forming composition was 10 or more, resulting in superior release properties compared to Example 15. Examples 1, 2, 9, 10, 12, and 13 show that when the carbodiimide compound content in the release layer-forming composition is 9% by mass or more, the solvent resistance is superior.

[0184] In Examples 1 and 19, it was found that the occurrence of unevenness defects was suppressed compared to Example 18 because the particle-containing layer contained a non-polyester resin.

Claims

1. It comprises a polyester substrate 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 the following conditions 1 and 2. Condition 1: The silicone compound contains an acidic group. Condition 2: The composition further contains at least one acid group-containing nonsilicone resin selected from the group consisting of acid group-containing urethane resins and acid group-containing olefin resins.

2. The release film according to claim 1, for use in manufacturing ceramic green sheets.

3. The release film according to claim 1 or claim 2, wherein the polyester substrate is substantially free of particles.

4. The composition further contains the acid group-containing nonsilicone resin, The release film according to any one of claims 1 to 3, wherein 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.

5. The release film according to any one of claims 1 to 4, wherein the mass ratio of the content of the silicone compound to the content of the carbodiimide compound in the composition is 0.1 to 10.

6. The release film according to any one of claims 1 to 5, wherein the thickness of the release layer is 0.001 μm to 0.2 μm.

7. It further contains a particle-containing layer, The release film according to any one of claims 1 to 6, comprising the release layer, the polyester substrate, and the particle-containing layer in this order.

8. The release film according to claim 7, wherein the particle-containing layer contains a non-polyester resin.

9. 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.

10. A method for manufacturing a release film according to any one of claims 1 to 9, A method for producing a release film, comprising the step of forming the release layer using a composition containing the silicone compound and the carbodiimide compound.

11. The method for producing a release film according to claim 10, wherein the step of forming the release layer is a step of applying the composition to one side of an unstretched polyester film or a uniaxially stretched polyester film to form the release layer.

12. A laminate comprising a release film according to any one of claims 1 to 9 and a layer containing ceramic.

Images