Release film for manufacturing ceramic green sheets, method for manufacturing the same, and laminate

Abstract

This invention provides a release film for manufacturing ceramic green sheets, or an application thereof, which can produce ceramic green sheets with suppressed unevenness defects and reduced thickness variations. [Solution] A release film for manufacturing a ceramic green sheet, comprising a polyester substrate and a release layer, having a film width of 1 m or more, the thickness of the polyester substrate being 40 times or more the thickness of the release layer, the pre-peak temperature measured by differential scanning calorimetry being 160°C or more and 225°C or less, the variation in the degree of crystallinity in the film width direction being 5.0% or less, and the release layer comprising a silicone resin as a release agent, a method for manufacturing the release film, and a laminate comprising the release film.

Description

Technical Field

[0001] The present disclosure relates to a release film for manufacturing a ceramic green sheet, a method for manufacturing the same, and a laminate.

Background Art

[0002] With the high performance and miniaturization of electronic devices, there is a demand for high performance and miniaturization of electronic components used in electronic devices. Among electronic components, for example, multilayer ceramic capacitors have an increasing number of mounting points on a substrate, and there is a strong demand for miniaturization. In the manufacture of multilayer ceramic capacitors, it is common to include a step of applying a ceramic slurry on a release layer of a release film and drying it to form a ceramic green sheet.

[0003] Patent Document 1 discloses a polyester film as a film for a support for green sheet forming in the process of manufacturing a multilayer ceramic capacitor. At least one surface of the polyester film has the intensity of an absorption peak derived from a polyester in a trans conformation obtained by infrared spectroscopic analysis measurement by the total reflection attenuation method (ATR-IR measurement) as A t , the intensity of an absorption peak derived from a gauche conformation as A g , and a ratio (trans conformation ratio) of the intensity of an absorption peak derived from a polyester in a trans conformation to the intensity of an absorption peak derived from a gauche conformation as A t / A g . When these values are used, a polyester film satisfying the following (1) and (2) is described. (1) The trans conformation ratio A t 0.5 / A g 0.5 in the region from the surface to a depth of 0.5 μm is 1.00 or more and 1.50 or less. (2) The above trans conformation ratio A t 0.5 / A g 0.5 and the trans conformation ratio A t 1.0 / Ag 1.0 to satisfy the following (Formula 1). (A t 1.0 / A g 1.0 )×1.1 ≦ A t 0.5 / A g 0.5 ···(Formula 1)

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When the inventors examined the release film including a polyester film and a release layer described in Patent Document 1, they obtained the findings that minute concave defects or minute convex defects (hereinafter also referred to as concavo-convex defects) occurred in the ceramic green sheet produced using such a release film, or thickness unevenness occurred.

[0006] This disclosure has been made in view of the above circumstances, and the problem to be solved by one embodiment of this disclosure is to provide a release film for manufacturing a ceramic green sheet capable of manufacturing a ceramic green sheet in which concavo-convex defects are suppressed and thickness unevenness is reduced. The problem to be solved by another embodiment of this disclosure is to provide a laminate including the above release film. Moreover, the problem to be solved by another embodiment of this disclosure is to provide a method for manufacturing a release film for manufacturing a ceramic green sheet capable of manufacturing a ceramic green sheet in which concavo-convex defects are suppressed and thickness unevenness is reduced.

Means for Solving the Problems

[0007] The means for solving the above problems include the following embodiments. <1> A release film for manufacturing ceramic green sheets, comprising a polyester substrate and a release layer, Having a film width of 1m or more, The thickness of the polyester substrate is 40 times or more the thickness of the release layer. The pre-peak temperature measured by differential scanning calorimetry is between 160°C and 225°C. The variation in the degree of crystallinity in the width direction of the film is 5.0% or less. Release film for manufacturing ceramic green sheets. <2> The variation in the thermal shrinkage rate in the direction perpendicular to the film width direction, and the variation in the thermal shrinkage rate in the film width direction, are both between 0.03% and 0.50%. <1> Release film for manufacturing ceramic green sheets as described above. <3> The intrinsic viscosity (IV) is 0.65 dL / g or higher. <1> or <2> Release film for manufacturing ceramic green sheets as described above. <4> The polyester substrate is substantially free of particles. <1> ~ <3> Release film for manufacturing ceramic green sheets as described in any one of the following. <5> Furthermore, it includes a particle-containing layer, The release layer, the polyester substrate, and the particle-containing layer are included in this order. <1> ~ <4> Release film for manufacturing ceramic green sheets as described in any one of the following. <6> The particle-containing layer contains a non-polyester resin. <5> Release film for manufacturing ceramic green sheets as described above. <7> The non-polyester resin is at least one resin selected from the group consisting of acrylic resin, urethane resin, and olefin resin. <6> Release film for manufacturing ceramic green sheets as described above. <8> The maximum protrusion height Sp of the particle-containing layer is 800 nm or less. <5> ~ <7> Release film for manufacturing ceramic green sheets as described in any one of the following. <9> A method for manufacturing a release film for ceramic green sheets, comprising a polyester substrate and a release layer, This process includes a heat setting step of heating a polyester film having a film width of 1 m or more. A method for manufacturing a release film for ceramic green sheets, comprising the heat setting step, wherein the maximum surface temperature of the polyester film is controlled to be within the range of 160°C to 225°C, and the variation in the maximum surface temperature in the film width direction is 5.0°C or less during heating. <10> <1> ~ <8> A laminate comprising a release film for manufacturing ceramic green sheets as described in any one of the above, and a layer containing ceramic. [Effects of the Invention]

[0008] According to one embodiment of the present disclosure, a release film for manufacturing ceramic green sheets is provided, which can produce ceramic green sheets in which unevenness defects are suppressed and thickness variations are reduced. According to another embodiment of the present disclosure, a laminate including the release film is provided. Furthermore, according to another embodiment of the present disclosure, a method for manufacturing a release film for manufacturing ceramic green sheets is provided, which can produce ceramic green sheets in which unevenness defects are suppressed and thickness variations are reduced. [Brief explanation of the drawing]

[0009] [Figure 1] This is a cross-sectional view of a ceramic green sheet obtained using conventional technology. [Figure 2] This is an observation image of a release film with streaky wrinkles on the surface of the release layer. [Modes for carrying out the invention]

[0010] The following describes the release film for manufacturing ceramic green sheets and the method for manufacturing the same as disclosed herein, and The laminate will be described in detail below. However, this disclosure is not limited in any way to the embodiments described below, and may be implemented with appropriate modifications within the scope of the purposes of this disclosure.

[0011] In this specification, a numerical range represented by "~" means a range that includes the numbers written before and after "~" as the lower and upper limits. In numerical ranges described stepwise in this specification, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described stepwise. Also, in numerical ranges described in this specification, the upper or lower limit stated in one numerical range may be replaced with the values ​​shown in the examples. In this specification, the amount of each component in a composition means the total amount of multiple substances present in the composition, unless otherwise specified, if there are multiple substances corresponding to each component in the composition. In this specification, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes, as long as their intended purpose is achieved. In this specification, a combination of two or more preferred embodiments is a more preferred embodiment.

[0012] In this specification, "release film having a film width of 1 m or more" means a long release film with a film width of 1 m or more. Therefore, in this specification, "longitudinal direction" means the longitudinal direction of the long release film and the polyester substrate contained in the release film, and is synonymous with the "conveying direction" and "machine direction" of the release film during its manufacture. In this specification, "width direction" means the direction perpendicular to the longitudinal direction. In this specification, "orthogonal" is not limited to strictly orthogonal, but includes approximately orthogonal. "Approximately orthogonal" means that the directions intersect within a range of 90° ± 5°, preferably within a range of 90° ± 3°, and more preferably within a range of 90° ± 1°. Furthermore, in this specification, "film width" means the distance between the two ends of the release film in the width direction.

[0013] [Release film for manufacturing ceramic green sheets] The release film for manufacturing ceramic green sheets according to this disclosure comprises a polyester substrate and a release layer. The release film for manufacturing ceramic green sheets according to this disclosure has a film width of 1 m or more, the thickness of the polyester substrate is 40 times or more the thickness of the release layer, and differential scanning calorimetry (DSC) The pre-peak temperature measured by (also known as) is between 160°C and 225°C, and the variation in crystallinity in the film width direction is 5.0% or less. Hereafter, the release film used for manufacturing ceramic green sheets will also be simply referred to as "release film."

[0014] The present inventors investigated the polyester film described in Patent Document 1 for use in manufacturing ceramic green sheets by forming a release layer as described in Patent Document 1. Through this investigation, they found that although the polyester film described in Patent Document 1 had good adhesion to the release layer after long-term storage, as described in Patent Document 1, ceramic green sheets manufactured using a release film containing such polyester film and release layer were subject to minute concave defects such as pinholes and convex defects (i.e., uneven surface defects). Furthermore, we also found that waviness occurs on one surface of the manufactured ceramic green sheet. Specifically, as shown in Figure 1, on one surface 12 of the obtained ceramic green sheet 10, a wavy waviness was observed along the film width direction of the release film, that is, a shape in which recesses and convex parts are continuously connected. Moreover, due to the above waviness (i.e., the shape in which recesses and convex parts are continuously connected), the ceramic green sheet It was also discovered that there were variations in thickness throughout the entire sheet. Such variations in the thickness of the ceramic green sheet were unacceptable because they would cause variations in the capacitance of the manufactured ceramic capacitors. The above-mentioned waviness occurs at the contact surface between the ceramic green sheet and the release layer of the release film, and is caused by the formation of streaky wrinkles on the surface of the release layer of the release film (i.e., the release surface). The streaky wrinkles that occur on the surface of the release layer of the release film extend in a streaky manner along the longitudinal direction of the release film and appear as irregularities in the width direction of the release film. For example, they can be observed as an irregular shape extending in the longitudinal direction in the area enclosed by the solid line in Figure 2. Note that the image (photograph) shown in Figure 2 shows only a portion of the observation area on the surface of the release layer of the release film.

[0015] The release film of this disclosure makes it possible to manufacture ceramic green sheets with suppressed unevenness defects and reduced thickness variations. The reason for this is not clear, but it is presumed to be as follows. The release film of this disclosure has a pre-peak temperature measured by DSC of 160°C to 225°C. By setting the pre-peak temperature of the DSC of the release film to 160°C or higher, it is possible to reduce variations in the degree of crystallinity and differences in thermal shrinkage of the release film, and it is presumed that thickness unevenness in the film width direction of the release film itself (for example, the streak-like wrinkles mentioned above) is reduced. Then, by using the release film of this disclosure, in which thickness unevenness in the film width direction is reduced, it is possible to manufacture a ceramic green sheet with reduced thickness unevenness as described above. Furthermore, by setting the pre-peak temperature of the DSC of the release film to 225°C or lower, it is presumed that the generation of oligomers produced by the thermal decomposition of the polyester substrate can be suppressed, and the precipitation of the generated oligomers on the surface of the release film can be suppressed. As a result, it is possible to suppress the occurrence of unevenness defects in the ceramic green sheet caused by the transfer of precipitates on the surface of the release film. Furthermore, since the release film of this disclosure has a variation in crystallinity of 5.0% or less in the film width direction, it is presumed that the thickness unevenness (for example, the streak-like wrinkles) of the release film itself in the film width direction is reduced. In this way, by using the release film of this disclosure, in which the thickness unevenness in the film width direction is reduced, it is possible to manufacture a ceramic green sheet with the above-mentioned thickness unevenness reduced.

[0016] In the release film of this disclosure, the thickness of the polyester substrate is 40 times or more, preferably 80 times or more, and more preferably 150 times or more, than the thickness of the release layer. Preferably, the thickness of the polyester substrate is 4000 times or less than the thickness of the release layer. Thus, since the thickness of the polyester substrate is much greater than the thickness of the release layer, the thickness of the polyester substrate accounts for a large portion of the total film thickness of the release film. Therefore, the various physical properties of the release film (specifically, the pre-peak temperature measured by DSC, degree of crystallinity, thermal shrinkage rate (described later), intrinsic viscosity, etc.) are mainly greatly influenced by the physical properties of the polyester substrate. In other words, if the thickness of the polyester substrate is 40 times or more than the thickness of the release layer, the physical properties of the release film can be controlled by adjusting the physical properties of the polyester substrate.

[0017] In the release film of this disclosure, the pre-peak temperature measured by DSC is 160°C to 225°C, and from the viewpoint of producing a ceramic green sheet with suppressed surface defects and reduced thickness unevenness, it is preferable that it is 160°C to 220°C or lower. Furthermore, from the viewpoint of producing a ceramic green sheet with suppressed surface defects and reduced thickness unevenness, it is preferable that it is 180°C to 210°C.

[0018] In this disclosure, “pre-peak temperature measured by DSC” means the highest temperature measured by DSC. This is the temperature of the first peak to appear. The pre-peak temperature corresponds to the highest film surface temperature (also called the heat-fixing temperature) of the polyester film during heat-fixing when obtaining the polyester substrate. Therefore, the pre-peak temperature measured by DSC of the release film of this disclosure mainly depends on the pre-peak temperature measured by DSC of the polyester substrate. The pre-peak temperature of the release film measured by DSC is a value obtained by conventional methods using differential scanning calorimetry (DSC).

[0019] In order to set the pre-peak temperature of the DSC of the release film of this disclosure to 160°C to 225°C, it is desirable to set the pre-peak temperature of the DSC of the polyester substrate to 160°C to 225°C.

[0020] In the release film of this disclosure, the variation in the degree of crystallinity in the film width direction is 5.0% or less, preferably 4.5% or less, more preferably 4.0% or less, and even more preferably 3.0% or less, from the viewpoint of being able to manufacture a ceramic green sheet with further reduced thickness unevenness. There is no particular limit to the variation in crystallinity in the film width direction; it may be 0% or greater than 0%, but in manufacturing, it is often 0.3% or greater. In order to reduce the variation in crystallinity in the film width direction of the release film of this disclosure to 5.0% or less, it is desirable to reduce the variation in crystallinity of the polyester substrate in the film width direction to 5.0% or less.

[0021] The method for measuring the variation in crystallinity in the film width direction involves cutting out three points from the entire film width in the film width direction: one point in the center (equally distanced from both ends in the film width direction) and two points at the ends. The crystallinity of the cut samples is measured, and the smaller of the two crystallinity values ​​at the ends (i.e., the crystallinity at the ends in the film width direction) is subtracted from the crystallinity of the center (i.e., the crystallinity of the center in the film width direction). Details of the measurement method are described in the Examples section.

[0022] Variations in crystallinity along the film width are particularly noticeable when the film width is 1 meter or longer. This is because, during the manufacturing of the polyester substrate, the temperature changes are large at the edges along the width of the polyester substrate, while temperature changes are less pronounced near the center of the width. Therefore, by suppressing temperature changes at the edges in the width direction during the manufacturing of the polyester substrate, it is possible to reduce variations in the degree of crystallinity in the width direction of the film.

[0023] The release film of this disclosure preferably has a variation in thermal shrinkage rate in the direction perpendicular to the film width direction and a variation in thermal shrinkage rate in the film width direction of 0.03% to 0.50%, more preferably 0.03% to 0.40%, and even more preferably 0.03% to 0.30%, from the viewpoint of being able to manufacture a ceramic green sheet with further reduced thickness unevenness. In order to achieve a variation of 0.03% to 0.50% in the thermal shrinkage rate of the release film of this disclosure in the direction perpendicular to the film width direction and in the film width direction, it is desirable to achieve a variation of 0.03% to 0.50% in the thermal shrinkage rate of the polyester substrate in the direction perpendicular to the film width direction and in the film width direction. Furthermore, the variation in the thermal shrinkage rate of the polyester substrate can be controlled by adjusting the variation in the crystallinity of the polyester substrate.

[0024] The thermal shrinkage rate of the release film in this disclosure is calculated using the following formula based on the film length of the release film before and after heat treatment at 150°C for 30 minutes. The thermal shrinkage rate of the release film [%] = (film length before heat treatment - film length after heat treatment) / (film length before heat treatment) × 100)

[0025] The variation in the heat shrinkage rate of the release film is determined by cutting out three points from the entire width of the film in the film width direction: one point in the center and two points at each end. Measuring the heat shrinkage rate at each point, subtracting the heat shrinkage rate at the end of the film width direction (the one with the larger difference from the heat shrinkage rate at the center) from the heat shrinkage rate at the center, and calculating the absolute value of this subtraction. In this case, if the direction in which the film length is measured is the film width direction, the variation in the heat shrinkage rate in the film width direction can be determined. If the direction in which the film length is measured is perpendicular to the film width direction (i.e., the longitudinal direction), the variation in the heat shrinkage rate in the direction perpendicular to the film width direction can be determined. Details of the measurement method are described in the Examples section.

[0026] The release film of this disclosure has an intrinsic viscosity (IV: Interisic Viscosity) of 0.65 dL / It is preferable that the concentration be 1 g or more, and more preferably 0.65 dL / g to 0.75 dL / g. If the intrinsic viscosity (IV) of the release film is 0.65 dL / g or higher, it is presumed that the polyester molecules become larger and less mobile. Therefore, a release film with an intrinsic viscosity (IV) of 0.65 dL / g or higher can suppress oligomer precipitation, making it possible to manufacture ceramic green sheets with suppressed surface defects. The intrinsic viscosity can be adjusted by the polymerization conditions.

[0027] Intrinsic viscosity (IV) is the ratio of solution viscosity (η) to solvent viscosity (η0) η r (=η / η0; relative viscosity) minus 1 is the specific viscosity (η sp =η r -1) is the value obtained by dividing the value by the concentration and extrapolating it to the state of zero concentration. The intrinsic viscosity (IV) is determined using an Ubbelohde viscometer by dissolving polyester in a 1,1,2,2-tetrachloroethane / phenol (=2 / 3 [mass ratio]) mixed solvent and measuring the viscosity of the solution at 25°C.

[0028] <Polyester base material> The release film of this disclosure includes a polyester substrate. 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.

[0029] 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.

[0030] The polyester substrate may contain components other than polyester resin (for example, catalysts, unreacted raw material components, particles, water, etc.).

[0031] 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. In this specification, "substantially particle-free" means that, with respect to the polyester substrate, fluorescent When elements originating from the particles are quantitatively analyzed by X-ray analysis, the particle content is defined as 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 from foreign substances, raw resin, 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.

[0032] [Properties of polyester substrates] (Thickness) The thickness of the polyester substrate is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 40 μm or less, from the viewpoint of controlling peelability. There is no particular lower limit to the thickness, but from the viewpoint 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 substrate is determined by preparing a section with a cross-section perpendicular to the main surface of the release film, 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 the section.

[0033] The method for manufacturing the polyester substrate and the details of the polyester resin contained in the polyester substrate will be described in detail in the section on the method for manufacturing the release film of this disclosure.

[0034] <Exfoliation layer> The release layer is provided to allow the release film to be peeled off. The ceramic green sheet is formed on the release surface of this release layer (i.e., the surface of the release layer opposite to the polyester substrate). In other words, the ceramic green sheet is manufactured to be removable from the release surface of the release film. 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 from the viewpoint of superior smoothness, it is preferable to provide it directly on the surface of the polyester substrate.

[0035] The composition of the release layer is not particularly limited as long as it can be manufactured in a way that allows the ceramic green sheet to be peeled off as described above, but it is preferable that it contains a release agent.

[0036] The components contained in the exfoliation layer are described in detail below.

[0037] [Removal agent] The release agent is not particularly limited, but examples include silicone resins, fluororesins, alkyd resins, and various waxes. Furthermore, the release agent is preferably a resin, and from the viewpoint of superior release properties of the ceramic green sheet, silicone resin is preferred. The release agent preferably has a cross-linked structure. In other words, the release layer is preferably a cross-linked film. To form a release agent having a crosslinked structure, one method is to form a release layer using a release layer-forming composition containing a crosslinking agent, as described later.

[0038] Silicone resin refers to a resin that has a silicone structure within its molecule. Examples of silicone resins include curable silicone resins, silicone graft resins, and modified silicone resins such as alkyl-modified resins, with reactive curable silicone resins being preferred. Examples of reactive curable silicone resins include addition reaction-type silicone resins, condensation reaction-type silicone resins, and ultraviolet or electron beam curable silicone resins.

[0039] Examples of silicone resins used in addition reactions include resins obtained by reacting polydimethylsiloxane, which has vinyl groups introduced to its terminals or side chains, with hydrodienesiloxane using a platinum catalyst and then curing the reaction. Examples of silicone resins used in condensation reactions include resins having a three-dimensional crosslinked structure, formed by condensing polydimethylsiloxane having OH groups at its ends with polydimethylsiloxane having H groups at its ends using an organotin catalyst. Examples of UV-curable silicone resins include those that utilize the same radical reaction as silicone rubber crosslinking, those that are photocured by introducing unsaturated groups, those that decompose onium salts with ultraviolet light or electron beams to generate strong acids, which then cleave epoxy groups and cause crosslinking, and those that are crosslinked by the addition reaction of thiols to vinylsiloxane. More specifically, examples include acrylate-modified polydimethylsiloxane and glycidoxy-modified polydimethylsiloxane.

[0040] [Other resins] The release layer may contain resins other than the release agent (hereinafter also referred to as "other resins") in addition to the resin used as a release agent. Other resins that can be used are known resins. Examples of other resins include UV-curable resins and thermosetting resins. Thermosetting resins are preferred from the viewpoint of being suitable for in-line coating and being able to produce ceramic green sheets with further suppression of surface defects and further reduction of thickness unevenness. Specific examples of thermosetting resins include acrylic resins, unsaturated polyester resins, melamine resins, epoxy resins, phenolic resins, olefin resins, and urethane resins. Acrylic resins, urethane resins, and olefin resins are preferred from the viewpoint of obtaining a good cured film. Furthermore, the release layer forming composition described later may contain other resins or compounds that serve as raw materials for synthesizing other resins, and polymerization initiators and / or catalysts, and the release layer may contain residues of the polymerization initiators and / or catalysts.

[0041] [Additives] The release layer may contain additives in addition to the resin and other resins used as release agents. Examples of additives include surfactants, light and heavy release additives for adjusting the release force, adhesion enhancers, and antistatic agents.

[0042] The release agent contained in the release layer may be used alone or in combination of two or more types. The release agent content in the release layer is preferably 0.1% to 98% by mass, and more preferably 0.5% to 50% by mass, relative to the total mass of the release layer. The content of other resins in the release layer is preferably 0% to 98% by mass, and more preferably 1% to 95% by mass, relative to the total mass of the release layer. The remaining material in the release layer, other than the resin used as a release agent and other resins, may be the residues of the above-mentioned additives, solvents, polymerization initiators, catalysts, etc. contained in the release layer forming composition.

[0043] [Properties of the release layer] (Thickness) The thickness of the release layer is preferably 10 nm to 1000 nm, and more preferably 30 nm to 700 nm, from the viewpoint of achieving a good balance between release performance and surface smoothness of the release layer. 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 the section.

[0044] (Surface free energy of the delamination surface) The surface free energy of the surface of the delamination layer (i.e., the delamination surface) is 5 mJ / m 2 ~50mJ / m 2 Preferably, 10 mJ / m 2 ~35mJ / m 2 This is preferable. Because the surface free energy of the peeling surface is within the above range, the ceramic green sheet is easily peeled off, and the coating properties of the ceramic slurry when manufacturing the ceramic green sheet are good. The surface free energy of the delamination surface can be adjusted by the type of resin and additives used to form the delamination layer.

[0045] The surface free energy of the peeled surface can be determined by using a contact angle meter (for example, "DROPMASTER-501" manufactured by Kyowa Interface Chemical Co., Ltd.) at 25°C, dropping droplets of purified water, methylene iodide, and ethylene glycol onto the peeled surface, measuring the contact angle 1 second after the droplets adhere to the surface, and calculating the energy from the obtained contact angles according to the Kitazaki-Hata method. The "surface free energy" obtained by the above method is the sum of the polar component and the hydrogen bonding component of the surface free energy.

[0046] (Maximum protrusion height Sp on the peeled surface, average surface roughness Sa) From the viewpoint of making the ceramic green sheet manufactured on the peeled surface smooth, it is preferable that the peeled surface be as smooth as possible. Specifically, the maximum protrusion height Sp of the peeled surface is preferably 1 nm to 60 nm, and more preferably 1 nm to 40 nm. Furthermore, the average surface roughness Sa of the peeled surface is preferably 0 nm to 10 nm, more preferably 0 nm to 5 nm, and even more preferably 0 nm to 2 nm. The maximum protrusion height Sp and average surface roughness Sa of the release surface can be adjusted by not incorporating particles into the release layer when forming it, and by selecting the resin and additives that form the release layer.

[0047] The maximum protrusion height Sp and average surface roughness Sa of the delamination surface are determined by measuring the surface of the delamination surface using an optical interferometer (Hitachi High-Tech Corporation's "Vertscan 3300G Lite") under the following conditions, and then analyzing the data using the built-in data analysis software. For measuring the maximum protrusion height Sp, five measurements are taken at different positions, and the maximum value obtained is taken as the maximum protrusion height Sp (indicated as P in the built-in data analysis software). Similarly, for measuring the average surface roughness Sa, five measurements are taken at different positions, and the average value obtained is taken as the average surface roughness Sa. The specific measurement conditions are as follows: Measurement mode: WAVE mode Objective lens: 50x Measurement area: 186μm x 155μm

[0048] <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.

[0049] 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 the winding quality of the release film (suppresses blocking), reduces the occurrence of scratches and defects during transport, and reduces transport wrinkles during high-speed transport.

[0050] 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 from the viewpoint of superior adhesion, it is preferable to provide it directly on the surface of the polyester substrate.

[0051] Furthermore, the particle-containing layer preferably contains particles and a binder, and may also contain additives.

[0052] The following describes the particles, binder, and additives.

[0053] (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, from the viewpoint of better transportability and suppression of transfer marks. Furthermore, from the viewpoint of having superior transportability and suppressing 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.

[0054] 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.

[0055] 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 (also called silicon dioxide particles), titania particles (also called titanium oxide particles), calcium carbonate, barium sulfate, and alumina particles (also called aluminum oxide particles). Among these, silica particles are preferred as the inorganic particles from the viewpoint of further improving haze and durability.

[0056] 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.

[0057] As the aggregated particles, fumed silica particles are preferred. A commercially available example is the Aerosil series manufactured by 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.

[0058] 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, for ease of transport. 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.

[0059] (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.

[0060] 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 more preferably at least one selected from the group consisting of acrylic resins, urethane resins, and olefin resins.

[0061] 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, so impurities such as oligomers are less likely 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.

[0062] The non-polyester resins mentioned above, such as acrylic resins, urethane resins, and olefin resins, are not particularly limited, and known resins can be used. The non-polyester resin is preferably an acid-modified resin, i.e., an acid group-containing non-polyester resin. Furthermore, the particle-containing layer may also contain polyester resin.

[0063] 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.

[0064] 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 viewpoint 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 unevenness defects in the ceramic green sheet.

[0065] 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, thereby suppressing the precipitation of impurities such as oligomers contained in the polyester substrate into the particle-containing layer, and thus suppressing unevenness 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.

[0066] As the olefin resin, an acid-modified olefin resin is preferred. Examples of acid-modified 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.

[0067] Examples of commercially available acid-modified 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 Chemicals, Inc.), such as Hitec S3121 and S3148K. Examples include the Arrowbase (registered trademark) 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 Sepolsion 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.

[0068] The polymer is not limited to polymers having urethane bonds in its main chain; known urethane resins, such as reaction products of polyisocyanate compounds and polyol compounds, can be used. From the standpoint of easy film formation by coating, the urethane resin is preferably a urethane resin having an acidic group, or a form containing a urethane resin and a dispersant. Examples of acidic groups include carboxyl groups. For example, by adjusting the structure and hydrophobicity (hydrophilicity) of the polyol compound and / or 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 unevenness defects in the ceramic green sheet. From the viewpoint of further suppressing unevenness defects, it is preferable that the urethane resin contains a polyester structure. Examples of commercially available 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.).

[0069] 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.

[0070] 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 unevenness defects, the binder content (preferably non-polyester resin) 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.

[0071] (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.

[0072] The particle-containing layer preferably contains a surfactant in order to improve the smoothness of the areas on the transport surface other than those where protrusions formed by the particles exist. The surfactant is not particularly limited, and examples include silicone-based surfactants, fluorine-based surfactants, and hydrocarbon-based surfactants. Among these, hydrocarbon-based surfactants are preferred.

[0073] 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.).

[0074] The fluorine-based 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).

[0075] 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.

[0076] Examples of commercially available anionic surfactants include, for example, 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.), and Kohacool® Examples include ON, L-40, and Phosphanol® 702 (all manufactured by Toho Chemical Industry Co., Ltd.), as well as Viewlight® A-5000 and SSS (both 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.).

[0077] Among hydrocarbon-based surfactants, anionic surfactants and / or nonionic surfactants are preferred, and anionic surfactants are more preferred.

[0078] Anionic hydrocarbon surfactants are preferable to have multiple hydrophobic end groups in order to further improve 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).

[0079] 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, from the viewpoint of superior surface smoothness.

[0080] 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

[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.

[0081] [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.

[0082] (Surface free energy of the particle-containing layer) The surface free energy at the surface of the particle-containing layer (i.e., the surface of the particle-containing layer opposite the polyester substrate) is 25 mJ / m 2 ~65mJ / m 2 Preferably, 25 mJ / m 2 ~60mJ / m 2 Preferably, 25 mJ / m 2 ~50mJ / m 2 More preferably, 30 mJ / m 2 ~45mJ / m 2 That is even more preferable. By keeping the surface free energy at the surface of the particle-containing layer within the above range, it is possible to suppress the deposition of impurities such as oligomers contained in the polyester substrate onto the particle-containing layer, thereby suppressing unevenness defects in the ceramic green sheet. Oligomers are low-molecular-weight by-products that are produced during the polymerization of polyester and are present as impurities in the polyester base material.

[0083] (Maximum protrusion height Sp of the particle-containing layer, average surface roughness Sa) From the viewpoint of further suppressing surface defects in ceramic green sheets during manufacturing, the maximum protrusion height Sp on the surface of the particle-containing layer is preferably 800 nm or less. In particular, when the particle-containing layer contains inorganic particles, the maximum protrusion height Sp on the surface of the particle-containing layer is preferably 300 nm or less. There is no particular lower limit to the maximum protrusion height Sp, but it is preferably 10 nm or more. Furthermore, the surface average roughness Sa on the surface of the particle-containing layer is preferably 0 nm to 10 nm, more preferably 0 nm to 5 nm, and even more preferably 1 nm to 3 nm. The method for measuring the maximum protrusion height Sp and average surface roughness Sa on the surface of the particle-containing layer is the same as the method for measuring the maximum protrusion height Sp and average surface roughness Sa on the delamination surface described above.

[0084] <Properties of the release film> [Thickness] From the viewpoint of superior release properties, 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. Furthermore, from the viewpoint of improving strength and processability, 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. The thickness of the release film shall be measured using a continuous stylus-type film thickness gauge. Details of the measurement method, etc., are described in the Examples section.

[0085] [Method for manufacturing release film] A method for manufacturing the release film described herein will be explained. The method for manufacturing the release film of this disclosure is not particularly limited as long as the release film of this disclosure described above is obtained, and known methods can be used.

[0086] In particular, from the viewpoint of being able to manufacture release films with high productivity, a preferred method for manufacturing release films is: An extrusion molding process to form an unstretched polyester film by extrusion molding, The stretching process includes a first stretching step of stretching an unstretched polyester film in either the conveying direction or the width direction to form a uniaxially stretched polyester film, and a second stretching step of stretching the uniaxially stretched polyester film in the other direction of the conveying direction and the width direction to form a biaxially stretched polyester film, which are performed either in stages or simultaneously. A manufacturing method is provided which includes a release layer forming 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 side of the polyester film to form a release layer.

[0087] The above manufacturing method yields a release film comprising a polyester substrate and a release layer. In other words, the polyester substrate in the obtained release film is preferably a film obtained by stretching an unstretched polyester film in both the transport direction and the width direction, i.e., a biaxially stretched polyester film.

[0088] Furthermore, the method for manufacturing the release film of this disclosure preferably further includes a particle-containing layer forming step, which is 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, by applying a particle-containing layer forming composition to the other side of the polyester film to form a particle-containing layer.

[0089] The above manufacturing method yields a release film containing a release layer, a polyester substrate, and a particle-containing layer in that order.

[0090] The method for manufacturing the release film of this disclosure is preferably, for example, in the following embodiments. In a preferred embodiment, in addition to the extrusion molding process, stretching process, release layer formation process, and particle-containing layer formation process performed as needed, A heat setting process in which the polyester film stretched in the stretching process is heated and heat-fixed, A heat relaxation step involves heating the heat-fixed polyester film at a lower temperature than the heat-fixing step to relax it, A cooling process to cool the polyester film that has been heat-relaxed by the heat relaxation process, It is preferable that it includes. In a preferred embodiment, by setting the heat setting temperature in the heat setting process, the heat relaxation temperature in the heat relaxation process, and the cooling rate of the polyester film in the cooling process to within the ranges described later, it becomes easier to suppress streak-like wrinkles that occur on the surface of the release layer of the release film (i.e., the release surface). By suppressing streak-like wrinkles that occur on the surface of the release layer of the release film, thickness unevenness in the ceramic green sheet manufactured using such a release film can be suppressed. In other words, from the viewpoint of manufacturing a ceramic green sheet with further suppression of thickness unevenness, it is desirable to manufacture the release film in the above preferred embodiment.

[0091] The following describes each step in a preferred embodiment of the method for manufacturing the release film of this disclosure. However, the method for manufacturing the release film of this disclosure is not limited to the preferred embodiment, and the following steps may be omitted as appropriate.

[0092] [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 polyester resin, which is the raw material, into a film to form an unstretched polyester film.

[0093] 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.

[0094] The polyester resin used in this process will be described below. In order to produce a polyester substrate that is substantially free of particles, it is preferable to use particle-free polyester resin pellets during the extrusion molding process.

[0095] (Polyester resin) The polyester resin used in this process is synthesized by copolymerizing a dicarboxylic acid component and a diol component. Furthermore, it is preferable that the polyester resin contains constituent units derived from a polyfunctional monomer (hereinafter also referred to as "trifunctional or more polyfunctional monomer" or simply "polyfunctional monomer") in which the sum of the number of carboxylic acid groups (a) and the number of hydroxyl groups (b) (a+b) is 3 or more.

[0096] Polyester resins can be obtained, for example, by esterifying and / or transesterifying a dicarboxylic acid component and a diol component using well-known methods, and more preferably by copolymerizing them with a trifunctional or polyfunctional monomer. Furthermore, the polyester resin may have a structure derived from the end-capturing agent.

[0097] The following describes the dicarboxylic acid components, diol components, polyfunctional monomers, and end-capturing agents.

[0098] -Dicarboxylic acid components- Examples of dicarboxylic acid components 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.

[0099] 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.

[0100] 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.

[0101] The dicarboxylic acid component may be used alone or in combination of two or more. When terephthalic acid is used as the dicarboxylic acid compound, it may be used alone or in combination with other aromatic dicarboxylic acids such as isophthalic acid, or with aliphatic dicarboxylic acids.

[0102] -Diol component- Examples of diol components include aliphatic diol compounds, alicyclic diol compounds, and aromatic diol compounds, with aliphatic diol compounds being preferred.

[0103] 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 and 1,3-benzenedimeth Examples include 1,4-benzenedimethanol and 9,9'-bis(4-hydroxyphenyl)fluorene.

[0104] Diol components may be used individually or in combination of two or more.

[0105] -Polyfunctional monomer- Examples of polyfunctional monomers include carboxylic acids having 3 or more carboxylic acid groups (a), their ester derivatives and acid anhydrides, polyfunctional monomers having 3 or more hydroxyl groups (b), and oxyacids having both hydroxyl groups and carboxylic acid groups in one molecule, with the sum of the number of carboxylic acid groups (a) and the number of hydroxyl groups (b) (a+b) being 3 or more. Suitable polyfunctional monomers include those obtained by adding l-lactide, d-lactide, hydroxybenzoic acid, and other oxyacids and their derivatives, or compounds in which multiple oxyacids are linked together, to the carboxyl terminus of the above-mentioned polyfunctional monomer.

[0106] Regarding the constituent units derived from polyfunctional monomers and their content, refer to the contents described in paragraphs

[0037] to

[0039] of Japanese Patent Publication No. 2013-047317, and the contents of the above publication are incorporated herein by reference. As polyfunctional monomers, those described in paragraphs

[0068] to

[0072] of Japanese Patent Publication No. 2013-047317 can also be used, and the contents of the above publication are incorporated herein by reference.

[0107] Polyfunctional monomers may be used individually or in combination of two or more.

[0108] -End-capturing agent- When obtaining polyester resin, an end-capping agent may be used as needed. By using an end-capping agent, a structure derived from the end-capping agent is 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 paragraphs

[0040] to

[0051] of Japanese Patent Publication No. 2013-047317, and the contents of the above publications are incorporated herein by reference.

[0109] The end-capturing agent may be used alone or in combination of two or more types.

[0110] - Manufacturing of polyester resin - As described above, esterification reactions and / or transesterification reactions are used in the production of polyester resins. Examples of obtainable polyester resins include polyethylene terephthalate (PET) and polyethylene-2,6-naphthalate (PEN), with PET being preferred. Among PET, those polymerized using one or more catalysts selected from germanium (Ge)-based catalysts, antimony (Sb)-based catalysts, aluminum (Al)-based catalysts, and titanium (Ti)-based catalysts are preferred, with those polymerized using a Ti-based catalyst being more preferred.

[0111] A preferred embodiment of the method for producing polyester resin will be described below. The method for producing polyester resin is not limited to this preferred embodiment. A preferred embodiment of a method for producing a polyester resin includes an esterification reaction step of using at least a dicarboxylic acid component and a diol component to obtain an esterification reaction product, and a polycondensation reaction step of undergoing a polycondensation reaction of the esterification reaction product obtained in the esterification reaction step to obtain a polycondensate.

[0112] • Esterification reaction process In the esterification reaction step, the dicarboxylic acid component and the diol component are polymerized in the presence of a catalyst. Specifically, first, the dicarboxylic acid component and the diol component are mixed with an organic chelate titanium complex, which is a Ti-based catalyst, prior to the addition of the magnesium compound and the phosphorus compound. Ti-based catalysts such as organic chelate titanium complexes are preferred because they have high catalytic activity for esterification reactions. At this time, the Ti-based catalyst may be added to the mixture of the dicarboxylic acid component and the diol component, or the dicarboxylic acid component (or diol component) may be mixed with the Ti-based catalyst first, and then the diol component (or dicarboxylic acid component) may be mixed. Alternatively, the dicarboxylic acid component, the diol component, and the Ti-based catalyst may be mixed simultaneously. There are no particular restrictions on the method of mixing, and it can be carried out by conventionally known methods.

[0113] As a Ti-based catalyst used in the esterification reaction step, an organic chelate titanium complex with an organic acid as a ligand is preferred. Examples of organic acids that can act as ligands include citric acid, lactic acid, trimellitic acid, and malic acid. Among these, an organic chelate complex with citric acid or a citrate as a ligand is preferred as the Ti-based catalyst. Furthermore, as the Ti-based catalyst, the Ti-based catalyst described in paragraph

[0080] and the titanium compounds described in paragraphs

[0082] to

[0084] and

[0086] of Japanese Patent Application Publication No. 2013-047317 can be used, and the contents of the above publication are incorporated herein by reference.

[0114] When polymerizing polyester, it is preferable to use a Ti-based catalyst at a concentration of 1 ppm to 50 ppm, more preferably 2 ppm to 30 ppm, and even more preferably 3 ppm to 15 ppm, in terms of titanium elemental value. By using this amount of Ti-based catalyst, the polyester resin will contain 1 ppm to 50 ppm of titanium elemental value.

[0115] In the esterification reaction step, it is preferable to add a magnesium compound as an additive to a system containing a Ti-based catalyst (e.g., an organic chelate titanium complex) in addition to the dicarboxylic acid and diol components, and then add a phosphorus compound as an additive.

[0116] Examples of magnesium compounds used as additives include magnesium salts such as magnesium oxide, magnesium hydroxide, magnesium alkoxide, magnesium acetate, and magnesium carbonate. Among these, magnesium acetate is preferred from the viewpoint of its solubility in ethylene glycol.

[0117] It is preferable to use the magnesium compound such that its concentration in the system is 50 ppm or more, preferably 50 ppm to 100 ppm, more preferably 60 ppm to 90 ppm, and even more preferably 70 ppm to 80 ppm, in terms of Mg element.

[0118] The phosphorus compound used as an additive is preferably a pentavalent phosphorus compound, and more preferably a pentavalent phosphate ester that does not have an aromatic ring as a substituent. Specifically, as a phosphorus compound, for example, phosphate esters having a lower alkyl group with 2 or fewer carbon atoms as a substituent [(OR)3-P=O;R=alkyl group with 1 or 2 carbon atoms] such as trimethyl phosphate and triethyl phosphate are preferred.

[0119] It is preferable to use the phosphorus compound such that its concentration in the system is 50 ppm to 90 ppm, preferably 60 ppm to 80 ppm, and more preferably 60 ppm to 75 ppm or less, in terms of the amount of element P.

[0120] A preferred embodiment of the esterification reaction step is to add a chelate titanium complex with 1 ppm to 30 ppm of citric acid or citrate as a ligand (based on Ti element) to the dicarboxylic acid component and the diol component before the esterification reaction is completed. Then, in the presence of the chelate titanium complex, add a magnesium salt of a weak acid (more preferably 70 ppm to 80 ppm, based on Mg element) in an amount of 60 ppm to 90 ppm. After this addition, add a pentavalent phosphate ester without an aromatic ring as a substituent (more preferably 65 ppm to 75 ppm or less, based on P element).

[0121] In the above embodiment, it is preferable that each of the chelated titanium complex (organic chelated titanium complex), magnesium salt (magnesium compound), and pentavalent phosphate ester (phosphorus compound) be added in the order described above, with each being at least 70% by mass of the total amount added.

[0122] Furthermore, the esterification reaction in the esterification reaction step can be carried out using a multi-stage apparatus consisting of at least two reaction vessels connected in series, under conditions of reflux of ethylene glycol, while removing the water or alcohol produced by the reaction from the system. In this case, it is preferable to prepare a slurry containing the dicarboxylic acid component and the diol component and continuously supply it to the reaction vessel.

[0123] The esterification reaction in the esterification reaction step may be carried out in one step or in multiple steps. When the esterification reaction is carried out in a single step, the esterification reaction temperature is preferably 230°C to 260°C, and more preferably 240°C to 250°C. When the esterification reaction is carried out in two stages, the temperature of the first reaction vessel is 230°C to 260°C (more preferably 240°C to 250°C), and the pressure is 1.0 kg / cm². 2 ~5.0 kg / cm 2 (more preferably 2.0 kg / cm³) 2 ~3.0 kg / cm 2 It is preferable that the esterification reaction temperature in the second reaction vessel is 230°C to 260°C (more preferably 245°C to 255°C), and the pressure is 0.5 kg / cm². 2 ~5.0 kg / cm 2 (More preferably 1.0 kg / cm³) 2 ~3.0 kg / cm 2 ) is preferable. When the esterification reaction is carried out in three or more stages, it is preferable to set the conditions for the intermediate esterification reaction to be between those of the first and final reaction vessels.

[0124] • Polycondensation reaction process In the polycondensation reaction step, the esterification reaction products (oligomers, etc.) generated in the esterification reaction step are subjected to a polycondensation reaction to produce polycondensate products. The polycondensation reaction may be carried out in one step or in multiple steps. In particular, it is preferable to carry out the polycondensation reaction in multiple steps.

[0125] When a polycondensation reaction is carried out in, for example, three stages, it is preferable to set the conditions in each reaction vessel as follows: The first reaction vessel has a temperature of 255°C to 280°C (more preferably 265°C to 275°C) and a pressure of 100 torr to 10 torr: 13.3 × 10 -3 ~1.3 × 10 -3 MPa (more preferably 50 torr to 20 torr: 6.67 × 10) -3 MPa ~ 2.67 × 10 -3 The pressure is preferably MPa. The second reaction vessel has a temperature of 265°C to 285°C (more preferably 270°C to 280°C) and a pressure of 20 torr to 1 torr: 2.67 × 10⁻¹⁰ -3 MPa ~ 1.33 × 10 -4 MPa (more preferably 10 torr to 3 torr: 1.33 × 10) -3 MPa~4.0×10 -4 It is preferable that the pressure be MPa. The third reaction vessel, which is the final reaction vessel, has a temperature of 270°C to 290°C (more preferably 275°C to 285°C) and a pressure of 10 torr to 0.1 torr: 1.33 × 10 -3 MPa ~ 1.33 × 10 -5 MPa (more preferably 5 torr to 0.5 torr) r: 6.67 × 10 -4 MPa ~ 6.67 × 10 -5 It is preferable that it be MPa.

[0126] Polyester resin is synthesized in the manner described above. The synthesized polyester resin is used as a raw material for polyester substrates. The synthesized polyester resin may further contain additives such as light stabilizers, antioxidants, UV absorbers, flame retardants, lubricants (fine particles), nucleating agents (crystallizing agents), and crystallization inhibitors.

[0127] ·Solid phase polymerization process The polyester resin obtained through the above process is preferably subjected to further solid-phase polymerization. By solid-phase polymerization of the polyester resin, the water content, degree of crystallinity, intrinsic viscosity (IV), etc., of the polyester substrate can be controlled.

[0128] In the solid-phase polymerization process, pelletized polyester resin is used. The solid-phase polymerization of polyester resin can be carried out by a continuous method (filling a tower with resin, heating it, allowing it to flow slowly for a predetermined time, and then sequentially discharging it) or by a batch method (putting resin into a container and heating it for a predetermined time). Solid-phase polymerization is preferably carried out in a vacuum or under a nitrogen atmosphere. The solid-phase polymerization temperature of the polyester resin is preferably 150°C to 250°C, more preferably 170°C to 240°C, and even more preferably 180°C to 230°C. Furthermore, the solid-phase polymerization time is preferably 1 to 100 hours, more preferably 5 to 100 hours, even more preferably 5 to 75 hours, and particularly preferably 5 to 30 hours. When the solid-phase polymerization time is within the above range, the intrinsic viscosity (IV) can be easily controlled to a preferred range.

[0129] [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.

[0130] 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.

[0131] 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 in the transport direction before stretching, 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.

[0132] In the transverse stretching process, it is preferable to preheat the uniaxially stretched polyester film before transverse stretching (also called the preheating process). 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.

[0133] [Particle-containing layer formation process] The particle-containing layer formation process involves applying a particle-containing layer formation composition to one side 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. In particular, it is preferable that the particle-containing layer formation step is performed between the first stretching step and the second stretching step. The particle-containing layer obtained by the particle-containing layer formation process is synonymous with the layer described in the section on particle-containing layers above. The following describes embodiments for providing the particle-containing layer-forming composition.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] Furthermore, the particle-containing layer-forming composition may also contain a crosslinking agent. The crosslinking agent is not particularly limited, and known agents can be used. Examples of crosslinking agents include melamine compounds, epoxy compounds, isocyanate compounds, carbodiimide compounds, and oxazoline compounds. For details on the melamine compound, epoxy compound, and isocyanate compound, refer to sections

[0081] to

[0083] of Japanese Patent Publication No. 2015-163457. As for carbodiimide compounds, see

[0038] ~ of Japanese Patent Publication No. 2017-087421. You can refer to the description in

[0040] . For carbodiimide compounds and isocyanate compounds, refer to sections

[0074] to

[0075] of International Publication No. 2018 / 034294. For oxazoline compounds, refer to sections

[0111] to

[0117] of Japanese Patent Publication No. 2013-058746 and sections

[0038] to

[0048] of Japanese Patent Publication No. 2015-160434. For crosslinking agents, refer to sections

[0082] to

[0084] of International Publication No. 2017 / 169844.

[0138] 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.

[0139] 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.

[0140] 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.

[0141] 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.

[0142] [Exfoliation layer formation process] The release layer formation process involves applying a release layer formation composition to one side of 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.

[0143] In particular, from the viewpoint of producing a release film with reduced thickness unevenness, 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 release layer formation step is preferably a step of applying a release layer formation composition to one side of an unstretched polyester film or a uniaxially stretched polyester film to form a release layer. By performing the release layer formation step at the above timing, the heating time of the polyester film in the manufacturing process is shortened, and the influence of thermal history can be reduced, thereby suppressing streak-like wrinkles in the release film, and as a result, thickness unevenness of the ceramic green sheet can be reduced.

[0144] 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 peeling layer formed by the peeling layer formation process is synonymous with the layer described in the section on peeling layers above.

[0145] 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.

[0146] 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.

[0147] 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.

[0148] 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.

[0149] 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.

[0150] 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.

[0151] [Heat setting process] The method for manufacturing the release film according to this disclosure may include a heat-setting step as a heat treatment of the polyester film obtained in the stretching step, after the stretching step. In the heat-setting process, the polyester film stretched in the stretching process is heated and heat-set. By crystallizing the polyester resin through heat-setting, shrinkage of the polyester substrate can be suppressed.

[0152] The heat setting process is preferably a process of heating a polyester film having a film width of 1 m or more. In this heat setting process, it is preferable to control the maximum film surface temperature of the polyester film to be within the range of 160°C to 225°C, and to heat the film so that the variation in the maximum film surface temperature in the film width direction is 5.0°C or less. The maximum achievable film surface temperature is the highest temperature reached on the surface of the polyester film during heat setting, and is also called the heat setting temperature. The maximum achievable film surface temperature can be measured using a radiation thermometer. The maximum achievable film surface temperature of a polyester film refers to the surface temperature at the center of the film in the width direction. Furthermore, the variation in the maximum achievable film surface temperature in the width direction of the film is calculated by measuring the surface temperature at a total of three points in the width direction of the film: one point in the center and two points at both ends, and subtracting the smaller of the two end surface temperatures from the central surface temperature. Furthermore, by measuring the maximum temperature reached on the surface of the polyester film during heat setting using the method described above, and determining whether the target temperature has been reached, the maximum surface temperature of the polyester film can be controlled by adjusting the heating conditions. As described above, when the maximum achievable film surface temperature is controlled to 160°C to 225°C, the pre-peak temperature measured by the DSC of the release film can be set to 160°C to 225°C. Furthermore, by keeping the variation in the maximum achievable film surface temperature in the film width direction to 0.5°C or less, the release film can be controlled. The variation in the degree of crystallinity in the film width direction can be reduced to 5.0% or less. The variation in the maximum film surface temperature in the film width direction is more preferably 3.0°C or less, even more preferably 2.0°C or less, and particularly preferably 1.5°C or less.

[0153] Furthermore, heating of the polyester film during heat setting may be performed from only one side of the polyester film, or from both sides. For example, when the molten material is cooled on the casting drum during the extrusion molding process, the molded polyester film is cooled differently on one side and the opposite side, making the film prone to curling. Therefore, it is preferable to perform the heating in the heat setting process on the side that was in contact with the casting drum during the extrusion molding process. By making the heated surface in the heat setting process the surface that was in contact with the casting drum, i.e., the cooled surface, curling can be eliminated. In this process, heating is preferably carried out such that the surface temperature of the heated surface immediately after heating in the heat-setting process is 0.5°C to 5.0°C higher than the surface temperature of the unheated surface on the opposite side. When the temperature of the heated surface during heat setting is higher than that of the opposite surface, and the temperature difference between the front and back surfaces is 0.5°C to 5.0°C, the curl of the film is more effectively eliminated. From the viewpoint of eliminating curl, the temperature difference between the heated surface and the unheated surface on the opposite side is more preferably 0.7°C to 3.0°C, and even more preferably 0.8°C to 2.0°C.

[0154] The edges of a polyester film in the width direction, perpendicular to the longitudinal direction, are prone to temperature drops during stretching due to the attachment of clips or the like, which can easily lead to temperature variations in the width direction and, consequently, variations in crystallinity. Therefore, it is preferable to heat the edges of the polyester film in the width direction during heat setting. In particular, it is more preferable to radiate heat the edges of the polyester film in the width direction during heat setting using a radiant heater such as an infrared heater. When radiant heating is performed, it is preferable to narrow the temperature variation in the film width direction to within 3.0°C. This makes it possible to reduce the variation in crystallinity in the film width direction to 5.0% or less, preferably 3.0% or less.

[0155] Furthermore, in addition to the heat setting process, the process may be configured to radiate the widthwise edges of the polyester film using a radiant heater such as an infrared heater in at least one of the preheating, stretching, and heat relaxation processes. Heating the widthwise edges reduces temperature variations in the widthwise direction, and consequently, variations in crystallinity. A higher improvement effect can be expected by performing additional heating not only during heat setting, but also in one or more of the preheating, stretching, and heat relaxation processes.

[0156] The heat-fixing temperature in the heat-fixing process, that is, the maximum surface temperature of the polyester film, is preferably 160°C to 225°C, more preferably 160°C to 220°C, and even more preferably 180°C to 210°C, as described above. The heating time in the heat setting process, i.e., the residence time in the heat setting section, is preferably 5 to 50 seconds, more preferably 8 to 40 seconds, and even more preferably 10 to 30 seconds. Here, residence time refers to the time during which the polyester film remains heated in the heat setting section.

[0157] [Thermal relaxation process] The method for manufacturing the release film according to this disclosure preferably includes a thermal relaxation step after the thermal setting step. In the heat relaxation process, it is preferable to heat the polyester film, which has been heat-fixed in the heat-fixing process, at a lower temperature than that of the heat-fixing process. This can alleviate residual strain in ester films. 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.

[0158] [Cooling process] The method for manufacturing the release film according to this disclosure preferably includes a cooling step of cooling the polyester film that has been thermally relaxed by the thermal relaxation step. Furthermore, by adjusting the cooling rate when cooling the heat-relaxed polyester film after the heat-setting process, it becomes easier to suppress the formation of streaky wrinkles on the surface of the release layer of the release film (i.e., the release surface). By suppressing the formation of streaky wrinkles on the surface of the release layer of the release film, it is possible to suppress thickness variations in the ceramic green sheets manufactured using such release films.

[0159] Methods for cooling the polyester film in the cooling process include, for example, blowing air (preferably cold air) onto the polyester film, and bringing the polyester film into contact with a temperature-controllable component (for example, a temperature-controlled roll).

[0160] The cooling rate of the polyester film in the cooling process is preferably 500°C / min to 4000°C / min, more preferably 700°C / min to 3000°C / min, and even more preferably 1000°C / min to 2500°C / min. Within this range, it is easier to suppress streak-like wrinkles that occur on the surface of the release layer of the release film, and a ceramic green sheet with suppressed thickness unevenness can be manufactured.

[0161] The cooling rate of a polyester film during the cooling process can be measured using a non-contact thermometer. For example, first, the surface temperature of the polyester film at the start of the cooling process and the surface temperature of the polyester film at the end of the cooling process are measured to obtain the temperature difference ΔT (°C). The cooling rate can be determined by dividing the obtained temperature difference ΔT (°C) by the cooling process time ta. The start of the cooling process refers to the time when the above-described cooling method is first applied to the conveyed polyester film, and the end of the cooling process refers to the time when the above-described cooling method is no longer applied to the polyester film. The cooling process time is the time from the start of the cooling process to the end of the cooling process. The cooling rate of the polyester film can be adjusted by various conditions in the cooling method described above, as well as the conveying speed of the polyester film.

[0162] In the method for manufacturing the release film described herein, it is preferable that the heat setting step, the heat relaxation step, and the cooling step described above be carried out in this order in succession. This is because it reduces the load (thermal history) on the polyester film due to repeated heating and cooling, reduces the strain inherent in the polyester film, and suppresses the aforementioned streak-like wrinkles in the release film.

[0163] In the above cooling process, it is also preferable to include a step (expansion step) in which the heat-relaxed polyester film is expanded in the width direction. Including an expansion step makes it easier to suppress the aforementioned streak-like wrinkles in the release film. The degree of expansion in the width direction of the polyester film due to the expansion process, i.e., before the start of the cooling process. The ratio of the polyester film width at the end of the cooling process to the polyester film width 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.

[0164] [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.

[0165] [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.

[0166] [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.

[0167] In the method for manufacturing a release film described herein, a method for forming a particle-containing layer is described in which a particle-containing layer is formed by applying a particle-containing layer-forming composition in the particle-containing layer formation step. 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 a laminated particle-containing layer by co-extrusion molding.

[0168] 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.

[0169] [Laminate] The laminate of this disclosure comprises the release film of this disclosure and a layer containing ceramic.

[0170] 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.

[0171] The ceramics included in the ceramic-containing layer are not particularly limited as long as they are ceramics included in the ceramic green sheet. Examples include ferroelectric materials such as barium titanate, and paraelectric materials such as titanium oxide and calcium titanate.

[0172] The ceramic-containing layer preferably contains a binder. The binder may be a ceramic. There are no particular restrictions on the binder included in the Lamic Green Sheet; for example, polyvinyl butyral can be used.

[0173] 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.

[0174] The method for applying the ceramic slurry is not particularly limited, and known methods such as the reverse roll method can be applied.

[0175] Furthermore, a ceramic green sheet can be obtained by peeling off the release film from the laminate of this disclosure. In other words, the layer containing ceramic powder in the laminate of this disclosure becomes the ceramic green sheet. [Examples]

[0176] The present disclosure will be further explained 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.

[0177] <Preparation of polyester resin> (Synthesis of polyester resin PET-1) As shown below, polyester resin was obtained using a direct esterification method in which terephthalic acid and ethylene glycol were directly reacted, water was removed by distillation, esterification was performed, and then polycondensation was carried out under reduced pressure, followed by continuous polymerization.

[0178] (1) Esterification reaction In the first esterification reactor, 4.7 tons of high-purity terephthalic acid and 1.8 tons of ethylene glycol were mixed over 90 minutes to form a slurry, and continuously supplied to the first esterification reactor at a flow rate of 3800 kg / h. Furthermore, an ethylene glycol solution of a titanium citrate chelate complex (VERTEC AC-420, manufactured by Johnson Matthey) in which citric acid is coordinated to Ti metal was continuously supplied, and the reaction was carried out at a temperature of 250 °C in the reactor under stirring with an average residence time of about 4.3 hours. At this time, the titanium citrate chelate complex was continuously added so that the Ti addition amount was 9 ppm in terms of elemental conversion value. At this time, the acid value of the obtained oligomer was 600 equivalents / ton. In this specification, "equivalent / t" represents the molar equivalent per ton. The reaction product was transferred to a second esterification reactor and reacted at a temperature of 250 °C in the reactor under stirring with an average residence time of 1.2 hours to obtain an oligomer with an acid value of 200 equivalents / ton. The second esterification reactor is internally partitioned into three zones, and an ethylene glycol solution of magnesium acetate was continuously supplied from the second zone so that the Mg addition amount was 75 ppm in terms of elemental conversion value, and then an ethylene glycol solution of trimethyl phosphate was continuously supplied from the third zone so that the P addition amount was 65 ppm in terms of elemental conversion value.

[0179] This reactant was transferred to a second esterification reactor and reacted at a temperature of 250 °C in the reactor under stirring with an average residence time of 1.2 hours to obtain an oligomer with an acid value of 200 equivalents / ton. The second esterification reactor is internally partitioned into three zones, and an ethylene glycol solution of magnesium acetate was continuously supplied from the second zone so that the Mg addition amount was 75 ppm in terms of elemental conversion value, and then an ethylene glycol solution of trimethyl phosphate was continuously supplied from the third zone so that the P addition amount was 65 ppm in terms of elemental conversion value.

[0180] (2) Polycondensation reaction The esterification reaction product obtained above was continuously supplied to a first polycondensation reactor and polycondensed at a reaction temperature of 270 °C and a reactor internal pressure of 20 torr (2.67×10 -3 MPa) with an average residence time of about 1.8 hours under stirring.

[0181] Furthermore, it was transferred to a second polycondensation reactor, and in this reactor, under stirring, the reactor internal temperature was 276 °C , and the reaction (polycondensation) was carried out under the conditions of a reactor internal pressure of 5 torr (6.67×10 -4 MPa) and a residence time of about 1.2 hours.

[0182] Next, the mixture is transferred to a third condensation reactor, where the reactor temperature is 278°C and the reactor pressure is 1.5 torr (2.0 × 10⁻⁶). -4 The reaction (polycondensation) was carried out under conditions of MPa with a residence time of 1.5 hours to obtain the reactant (polyethylene terephthalate (PET)).

[0183] Next, the resulting reaction product was extruded in strand form into cold water and immediately cut to produce polyester resin pellets (cross-section: major diameter approximately 4 mm, minor diameter approximately 2 mm, length: approximately 3 mm).

[0184] The obtained polyester resin was measured using high-resolution radiofrequency inductively coupled plasma-mass spectrometry (HR-ICP-MS; AttoM, manufactured by SII Nanotechnology Co., Ltd.) as follows: The concentrations were Ti=9 ppm, Mg=75 ppm, and P=60 ppm. Although the amount of P decreased slightly compared to the initial amount added, it is presumed that this was due to volatilization during the polymerization process.

[0185] (3) Solid-phase polymerization reaction Solid-phase polymerization was carried out on the polyester resin pellets obtained as described above using a batch method. Specifically, after placing the polyester resin pellets into a container, a pre-crystallization treatment was performed at 150°C under vacuum and stirring, followed by a solid-phase polymerization reaction at 190°C for 7 hours. In this manner, polyester resin PET-1 was obtained.

[0186] (Polyester resin PET-2~PET-4) In the synthesis of polyester resin PET-1, polyester resins PET-2 to PET-4 were obtained in the same manner, except that the solid-phase polymerization time was changed from 7 hours to 12 hours (P-2), 9 hours (P-3), or 0 hours (P-4).

[0187] (Polyester resin PET-5) Polyester resin PET-5 was obtained by adding an ethylene glycol solution of silica particles to the polyester resin PET-1 obtained in the synthesis of polyester resin PET-1, in a content of 1% by mass relative to polyester resin PET-1.

[0188] <Example 1> (Extrusion molding process) Polyester resin PET-1 was dried to a moisture content of 20 ppm or less and then fed into the hopper of a 50 mm diameter single-screw compounding extruder. The polyester resin PET-1 was melted at 300°C and extruded from the die through a gear pump and filter (pore size 20 μm) under the extrusion conditions described below. In this process, the molten resin was extruded under conditions of a 1% pressure fluctuation and a 2% temperature distribution of the molten resin. Specifically, the back pressure in the extruder barrel was set to 1% higher than the average pressure inside the extruder barrel, and the extruder piping temperature was heated to 2% higher than the average temperature inside the extruder barrel. When extruding from the die, the molten resin was extruded onto a cooling cast drum and made to adhere to the cast drum using an electrostatic application method. The molten resin was cooled by setting the temperature of the cast drum to 25°C and applying 25°C cold air from a cold air generator installed facing the cast drum. The unstretched polyester film (unstretched polyester film 1) was peeled off by a peeling roll positioned opposite the cast drum.

[0189] (Longitudinal stretching process) An unstretched polyester film 1 was passed between two pairs of nip rolls with different peripheral speeds and stretched in the longitudinal direction (conveying direction) under the following conditions to produce a uniaxially stretched polyester film (longitudinally stretched polyester film 1). Preheating temperature: 80℃ Longitudinal stretching temperature: 90℃ Vertical stretching ratio: 3.6 times Longitudinal tensile stress: 12 MPa

[0190] (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 (longitudinally stretched polyester film 1) 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 where the particle-containing layer was applied 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 applied in-line to the 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 and the thickness of the release layer after transverse stretching, as described later, would be 60 nm.

[0191] [Preparation of composition A1 for forming a particle-containing layer] A particle-containing mixture A was prepared by mixing the components listed below. The prepared particle-containing mixture A was subjected to filtration using a filter with a pore size of 6 μm (F20, manufactured by MAHLE FILES SYSTEMS, Inc.) and membrane degassing (2×6 radial flow superphobic, manufactured by POLIPORE, Inc.) to obtain a particle-containing layer-forming composition A1. • Organic particles A (MP1000, manufactured by Soken Chemical Co., Ltd., non-crosslinked acrylic particles, solid content 100% by mass): 8 parts by mass • Organic particles B (Nipol® UFN1008, manufactured by Nippon Zeon Co., Ltd., polystyrene aqueous dispersion, solid content 20% by mass): 8 parts by mass • Acrylic resin (aqueous dispersion of a copolymer obtained by polymerizing methyl methacrylate, styrene, 2-ethylhexyl acrylate, 2-hydroxyethyl methacrylate, and acrylic acid in a mass ratio of 59:8:26:5:2, solid content concentration 25% by mass): 141 parts by mass • Urethane resin (Superflex® 210, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., ester-based urethane aqueous dispersion, solid content concentration 35% by mass): 38 parts by mass · Anionic hydrocarbon surfactant (Lapizol (registered trademark) A-90, di-2-ethylhexyl sodium sulfosuccinate, manufactured by NOF Corporation, solid content concentration 1% by mass aqueous dilution): 12 parts by mass · Carbodiimide crosslinking agent (Carbodilite (registered trademark) V-02-L2, manufactured by Nisshinbo Industries, Inc., an aqueous crosslinking agent with a hydrophilic segment added to a polycarbodiimide resin, solid content concentration 40% by mass): 20 parts by mass · Benzyl alcohol: 4 parts by mass · Water: 769 parts by mass

[0192] [Preparation of Release Layer Forming Composition L1] A mixed solution L was prepared by mixing each of the components shown below. The prepared mixed solution L was subjected to the same filtration treatment and film degassing as the particle-containing layer forming composition A1 to obtain the release layer forming composition L1. · Silicone emulsion (DEHESIVE (registered trademark) EM 480 JP, manufactured by Asahi Kasei Wacker Silicone Co., Ltd.): 200 parts by mass · Silicone emulsion (CROSSLINKER V72, manufactured by Asahi Kasei Wacker Silicone Co., Ltd.): 30 parts by mass · Silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.): 1 part by mass · Water: 770 parts by mass

[0193] (Transverse Stretching Process) The longitudinally stretched polyester film 1 (longitudinally stretched polyester film 1) provided with a particle-containing layer and a release layer was tensioned under the following conditions in the film width direction orthogonal to the longitudinally stretched direction (longitudinal direction) and transversely stretched. <Conditions> · Preheating temperature: 110 °C · Stretching temperature (transverse stretching temperature): 120 °C · Stretching ratio (transverse stretching ratio): 4.4 times · Stretching stress (transverse stretching stress): 18 MPa

[0194] (Heat Fixing Process) Next, while controlling the maximum surface temperature of the polyester film to the range shown below, the wind speed of the hot air emitted from the hot air blowing nozzle was finely adjusted to heat the film so that the variation in the maximum surface temperature in the width direction was within the range shown below, and the film was crystallized (heat setting process). At this time, both ends in the width direction of the film were radiantly heated from the cast surface side that had been in contact with the cast drum during the film forming process using an infrared heater (heater surface temperature: 450°C). ·Maximum film surface temperature (thermal fixation temperature: T 熱固定 ): Temperatures shown in Table 1 below [°C] • Maximum film surface temperature reached in the film width direction (thermal fixed temperature: T) 熱固定 Variation in temperature: As shown in Table 1 below [°C] Note that the above T 熱固定 (Maximum film surface temperature) and T in the film width direction 熱固定 The variation is the value measured using the method described above.

[0195] (Thermal relaxation process) The heat-set polyester film was heated to the following temperature to relieve tension in the film. At this time, both ends in the width direction of the film were radiantly heated from the cast side using an infrared heater (heater surface temperature: 350°C), similar to the heat-setting process. ·Thermal relaxation temperature (T 熱緩和 ): 150℃ • Thermal relaxation rate: TD direction (film width direction) = 5% MD direction (direction perpendicular to the film width direction) = 5%

[0196] (cooling process) Next, the polyester film after heat relaxation was cooled to 70°C at a cooling rate of 1500°C / min.

[0197] (Film collection) After cooling was complete, 20 cm was trimmed from both ends of the polyester film. Then, knurling was applied to both ends with a width of 10 mm, and the film was wound up under a tension of 25 kg / m.

[0198] In this manner, a release film with a width of 1.5 m, a length of 7000 m, and a thickness of 31 μm was prepared. In the release film, the thickness of the polyester substrate was 517 times the thickness of the release layer.

[0199] <Examples 2-9, Examples 12-14> The release film was prepared in the same manner as in Example 1, except that the manufacturing process and physical properties of the release film were modified as appropriate, as shown in Table 1. Furthermore, by changing the type of resin (i.e., binder) in particle-containing layer-forming composition A1, particle-containing layers containing the resins listed in Table 1 were formed.

[0200] <Example 10> A biaxially oriented film containing a particle-containing layer and a polyester substrate was prepared in the same manner as in Example 7, except that a release layer was not formed. The obtained film was unwound, and the release layer-forming composition L2 described below was applied to the side of the polyester substrate opposite to the particle-containing layer so that the cured thickness was 60 nm. After drying the formed coating film at 90°C, it was heat-cured by heating at 120°C for 1 minute to form a release layer and prepare a release film.

[0201] [Preparation of Composition L2 for Forming the Release Layer] A mixture L was prepared by mixing the components listed below. The prepared mixture L was subjected to the same filtration treatment and membrane degassing as for composition A1 for forming a particle-containing layer to obtain composition L2 for forming a peeling layer. • Acrylic resin (a copolymer obtained by polymerizing methyl methacrylate, stearyl methacrylate, 2-hydroxyethyl methacrylate, and methacrylic acid in a mass ratio of 47:26:20:7, solids content 40% by mass toluene solution): 1.75 parts by mass • Polyester-modified silicone resin (BYK-370, manufactured by Bic Chemie Japan Co., Ltd., solid content concentration 25% by mass): 0.05 parts by mass • Thermopolymerizable compound (hexamethoxymethylmelamine, manufactured by Tokyo Chemical Industry Co., Ltd., solids content 10% by mass): 0.25 parts by mass • Acid catalyst (p-toluenesulfonic acid, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., solid content 100% by mass): 0.02 parts by mass Methyl ethyl ketone: 58 parts by mass • Toluene: 40 parts by mass

[0202] <Example 11> A release film was prepared in the same manner as in Example 10, except that an unstretched film was prepared by co-extruding polyester resin PET-1 and polyester resin PET-5 in the extrusion molding process.

[0203] <Comparative Example 1> The polyester resins used in co-extrusion were changed to polyester resin PET-3 and polyester resin PET-5, and the heat setting temperature was changed to T 熱固定 The release film was prepared in the same manner as in Example 11, except that the method was modified to eliminate radiant heating with an infrared heater and to change the thickness of the release film.

[0204] <Comparative Example 2> Polyester resin PET-1 was changed to polyester resin PET-4, and the heat setting temperature: T 熱固定 The release film was prepared in the same manner as in Example 10, except that the method was changed and radiant heating with an infrared heater was not performed.

[0205] <Comparative Example 3> In the extrusion molding process, an unstretched film was produced by co-extruding polyester resin PET-4 and polyester resin PET-5, and the heat setting temperature was T 熱固定 The release film was prepared in the same manner as in Example 7, except for the change made to [specific component].

[0206] <Comparative Example 4> The polyester resins used in co-extrusion were changed to polyester resin PET-1 and polyester resin PET-5, and the heat setting temperature was changed to T 熱固定 Change the settings and use radiant heating with an infrared heater. The release film was prepared in the same manner as in Comparative Example 3, except that the thickness of the release film was changed, without performing the necessary modifications.

[0207] The details of each component listed in Table 1 are as follows: Note that PET-1 to PET-5 are the polyester resins PET-1 to PET-5 mentioned above.

[0208] (resin) • Acrylic: Acrylic resin (a copolymer obtained by polymerizing methyl methacrylate, styrene, 2-ethylhexyl acrylate, 2-hydroxyethyl methacrylate, and acrylic acid in a mass ratio of 59:8:26:5:2) • Urethane: Urethane resin (Superflex® 210, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., ester-based urethane aqueous dispersion) • Olefin: Olefin resin (Zyxen NC, manufactured by Sumitomo Seika Co., Ltd.)

[0209] <Measurement> The following various measurements were performed using the prepared release film. The measurement results are shown in Table 1 below.

[0210] (1) Pre-peak temperature, intrinsic viscosity, and thickness of the delamination layer as measured by DSC The pre-peak temperature, intrinsic viscosity, and thickness of the release layer of the release film, as measured by DSC, were measured using the method described above.

[0211] (2) Variation in degree of crystallinity Three measurement samples were obtained by cutting out three points from the entire width of the release film: one point in the center and two points at each end, with a width of 30 mm and a length of 120 mm. The degree of crystallinity was measured for each of the three measurement samples, and the variation in the degree of crystallinity in the film width direction was calculated by subtracting the smaller of the two crystallinity values ​​of the two end samples from the degree of crystallinity of the central sample. The degree of crystallinity was calculated from the density of the film. Specifically, the density of the film X (g / cm³) 3 ), density Y (g / cm³) at 0% crystallinity3 ), density Z (g / cm³) at 100% crystallinity 3 Using ), the degree of crystallinity X is calculated using the following formula. The percentage c was derived. The density was measured in accordance with JIS K 7112:1999. Xc = {Z × (XY)} / {X × (ZY)} × 100

[0212] (3) Variation in thermal shrinkage rate The release film was cut to obtain a sample piece M measuring 30 mm in width and 120 mm in length. Two reference lines were drawn on the sample piece M at a distance of 100 mm along its length, and it was left in a 150°C oven for 30 minutes under no tension. After that, the sample piece M was cooled to room temperature, and the distance between the two reference lines was measured. This value was set to A mm, and the formula "100 × (100 - A) / 100" was calculated to obtain the thermal shrinkage rate in the length direction. Furthermore, a sample piece L measuring 30 mm in the longitudinal direction and 120 mm in the width direction was obtained. Two reference lines were drawn on this sample piece L at a distance of 100 mm in the width direction, and measurements and calculations were performed in the same manner as for sample piece M. The obtained value was defined as the thermal shrinkage rate in the width direction. The above procedure was performed using a sample cut from the entire width of the release film at three points: one in the center and two at each end. The absolute value was calculated by subtracting the thermal shrinkage rate at the end (the one with the larger difference from the thermal shrinkage rate at the center) from the thermal shrinkage rate at the center, and this was used as the variation in thermal shrinkage rate in both the longitudinal (MD) and widthwise (TD) directions.

[0213] (4) Measurement of thickness The thickness of the release film was measured at five different points using a contact-type film thickness gauge (manufactured by Anritsu Corporation). The arithmetic mean of the obtained measurements was calculated and defined as the thickness of the release film.

[0214] The fabricated release films were used to evaluate local protrusions and thickness variations in the particle-containing layer, as well as surface defects in the ceramic green sheet. The evaluation method is as follows.

[0215] <Local protrusions> The surface of the particle-containing layer of the fabricated release film was measured using an optical interferometer (Vertscan 3300G Lite, manufactured by Hitachi High-Tech Corporation) under the following conditions, and then analyzed using the built-in data analysis software (VS-Measure5). We performed 100 measurements at different measurement locations and determined the total number of protrusions with a height exceeding 50 nm. (Measurement conditions) • Measurement mode: WAVE mode • Objective lens: 50x ·Measurement area: 186μm×155μm

[0216] (Evaluation Criteria) A: The maximum protrusion height Sp is 800 nm or less, and the total number of protrusions with a height exceeding 50 nm is 0 to 2. B: The maximum protrusion height Sp is 800 nm or less, and the total number of protrusions with a height exceeding 50 nm is between 3 and 9. C: The maximum protrusion height Sp is greater than 800 nm, or the total number of protrusions with a height exceeding 50 nm is 10 or more.

[0217] <Uneven thickness> (Preparation of black slurry) The black slurry was prepared by mixing the following components and dispersing them in a ball mill. • Polyvinyl butyral (manufactured by Sekisui Chemical Co., Ltd., S-Rec BX-5): 5 parts by mass • Resin-coated carbon black prepared in accordance with paragraphs

[0036] to

[0042] of Japanese Patent Publication No. 5320652: 10 parts by mass • Mixed solvent of toluene and ethanol in a mass ratio of 6:4: 45 parts by mass

[0218] The release films prepared in each example and comparative example were transported at 70 m / min, and the black slurry was applied to the release layer using a slit nozzle so that the thickness after drying was 0.5 μm. The coated film was then dried under a temperature of 90°C to form a black layer. A release film with a black layer was placed on a light table, and the color unevenness of the black layer was visually observed from a distance of 1 m from the release film and evaluated according to the evaluation criteria below.

[0219] (Evaluation Criteria) A: No color unevenness was observed in the black layer. B: Slight color unevenness was observed in the black layer. C: Color unevenness in the black layer was clearly observed. If no color unevenness is observed in the black layer, it indicates that the thickness of the black layer is uniform, i.e., there is no thickness unevenness. It is presumed that by using a release film that can form a black layer without color unevenness, overall thickness unevenness of the ceramic green sheet can be suppressed.

[0220] <Unevenness / Defects> (Preparation of ceramic slurry) 100 parts by mass of barium titanate powder (BaTiO3; manufactured by Sakai Chemical Industry Co., Ltd., product name "BT-03") as a ceramic, 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 obtained by removing the beads from the resulting dispersion.

[0221] The release films obtained in each example and comparative example were cut to a width of 250 mm and a length of 10 m. The cut release films were left at room temperature and humidity (23°C, 50% RH) for 12 months. After storage, the entire release surface of the release film was coated with the following ceramic slurry using a die coater so that the film thickness after drying was 1 μm. The resulting coating was then dried in a dryer at 100°C for 2 minutes. This yielded a laminate containing a release film and a ceramic-containing layer. Since the ceramic-containing layer becomes a ceramic green sheet after the release film is peeled off the laminate, the laminate will hereafter be referred to as a release film with a ceramic green sheet. The release film with the ceramic green sheet was first rolled up. Then, a fluorescent light was shone from the release film side of the unrolled ceramic green sheet release film, and the surface of the ceramic green sheet was measured over 1 meter. 2 The area was visually inspected to check for the presence of irregularities such as pinholes. The number of irregularities identified was used to evaluate the quality of the material. The evaluation criteria are as follows:

[0222] (Evaluation Criteria) A: No irregularities or defects were found in the ceramic green sheet. B: One to nine irregularities were found in the ceramic green sheet. C: More than 10 irregularities were found in the ceramic green sheet.

[0223] The evaluation results are shown in Table 1. In Table 1, if the method for forming the particle-containing layer is indicated as "in-line," it means that the particle-containing layer formation process was performed between the longitudinal stretching process and the transverse stretching process, similar to Example 1 described above. If the method for forming the particle-containing layer is indicated as "co-extrusion," it means that the unstretched polyester film and the particle-containing layer were formed by co-extrusion during the extrusion molding process. Furthermore, if the release layer formation process is described as "in-line," it means that, as in Example 1 above, the release layer formation process was performed between the longitudinal stretching process and the transverse stretching process. If the release layer formation process is described as "off-line," it means that a biaxially oriented film containing a particle-containing layer and a polyester substrate was prepared, wound up, and then, after unwinding, the release layer was formed.

[0224] [Table 1]

[0225] It is presumed that the release films of Examples 1 to 14 can be used to manufacture ceramic green sheets with less color unevenness in the black layer and reduced thickness unevenness. Furthermore, it is presumed that the release films of Examples 1 to 14 can be used to manufacture ceramic green sheets with fewer surface defects. We were able to manufacture the product.

[0226] On the other hand, the release films of Comparative Examples 1 and 2 had a pre-peak temperature of over 225°C as measured by DSC, and a variation in crystallinity in the width direction of over 5.0%, indicating thickness unevenness. It is presumed that large ceramic green sheets were being manufactured, and furthermore, many irregularities and defects were observed in the manufactured ceramic green sheets. The release film of Comparative Example 3 has a variation in crystallinity in the width direction of 5.0% or less. However, since the pre-peak temperature measured by DSC exceeded 225°C, many surface defects were observed in the manufactured ceramic green sheets. The release film of Comparative Example 4 has a pre-peak temperature of less than 160°C as measured by DSC, and the variation in crystallinity in the width direction is more than 5.0%, indicating large thickness variations. It was speculated that Lamic Green Sheets would be manufactured there. [Explanation of Symbols]

[0227] 10: Ceramic Green Sheet 12: One side of the ceramic green sheet

Claims

1. A release film for manufacturing ceramic green sheets, comprising a polyester substrate and a release layer, Having a film width of 1 meter or more, The thickness of the polyester substrate is 40 times or more than the thickness of the release layer. The pre-peak temperature measured by differential scanning calorimetry is between 160°C and 225°C. The variation in the degree of crystallinity in the width direction of the film is 5.0% or less. The aforementioned release layer contains a silicone resin as a release agent. Release film for manufacturing ceramic green sheets.

2. The release film for manufacturing ceramic green sheets according to claim 1, wherein the variation in the thermal shrinkage rate in the direction perpendicular to the film width direction and the variation in the thermal shrinkage rate in the film width direction are both 0.03% to 0.50%.

3. The release film for manufacturing ceramic green sheets according to claim 1, wherein the intrinsic viscosity (IV) is 0.65 dL / g or more.

4. The release film for manufacturing ceramic green sheets according to claim 1, wherein the polyester substrate is substantially free of particles.

5. Furthermore, it includes a particle-containing layer, The release film for manufacturing a ceramic green sheet according to claim 1, comprising the release layer, the polyester substrate, and the particle-containing layer in this order.

6. The release film for manufacturing ceramic green sheets according to claim 5, wherein the particle-containing layer contains a non-polyester resin.

7. The release film for manufacturing ceramic green sheets according to claim 6, wherein 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 for manufacturing ceramic green sheets according to claim 5, wherein the maximum protrusion height Sp of the particle-containing layer is 800 nm or less.

9. The release layer further comprises at least one resin selected from the group consisting of acrylic resin, unsaturated polyester resin, melamine resin, epoxy resin, phenolic resin, olefin resin, and urethane resin, as described in claim 1, for the production of ceramic green sheets.

10. A method for manufacturing a release film for ceramic green sheets, comprising a polyester substrate and a release layer, An extrusion molding process to form an unstretched polyester film by extrusion molding, A stretching process that 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 in stages or simultaneously. A heat setting process involves heating and heat-fixing a polyester film having a film width of 1 m or more, which has been stretched in the stretching process. The process includes a release layer forming step, in which a release layer forming composition is applied to one side of a polyester film to form a release layer, between the extrusion molding step and the stretching step, or between the first stretching step and the second stretching step, A method for manufacturing a release film for ceramic green sheets, comprising the heat setting step, wherein the maximum surface temperature of the polyester film is controlled to be within the range of 160°C to 225°C, and the variation in the maximum surface temperature in the film width direction is 5.0°C or less during heating.

11. The method for manufacturing a release film for ceramic green sheets according to claim 10, wherein the release layer formation step is a step of applying a release layer formation composition to one side of a polyester film between a first stretching step and a second stretching step to form a release layer.

12. The method for producing a release film for manufacturing a ceramic green sheet according to claim 10, wherein the release layer forming composition comprises a release agent and at least one resin selected from the group consisting of acrylic resin, unsaturated polyester resin, melamine resin, epoxy resin, phenolic resin, olefin resin, and urethane resin.

13. The method for manufacturing a release film for ceramic green sheets according to claim 12, wherein the release agent is a silicone resin.

14. A laminate comprising a release film for manufacturing ceramic green sheets according to any one of claims 1 to 9, and a layer containing ceramic.

Images