WO2024058163A1

WO2024058163A1 - Mold release film and method for producing same

Info

Publication number: WO2024058163A1
Application number: PCT/JP2023/033171
Authority: WO
Inventors: 健斗重野; 真司矢野
Original assignee: 東洋紡株式会社
Priority date: 2022-09-16
Filing date: 2023-09-12
Publication date: 2024-03-21
Also published as: TW202417249A

Abstract

Provided are: a mold release film that enables a reduction in the amount of organic solvents which are hazardous to the human body and which have an adverse impact on the environment, and achieves both good wettability and easy release properties of a thin-film resin sheet, particularly, a thin-film ceramic green sheet; and a method for producing the mold release film. The present invention pertains to: a mold release film having a mold release layer on at least one surface of a polyester film; and a method for producing the mold release film. The mold release layer is obtained by reacting and solidifying an aqueous coating composition. The aqueous coating composition contains 10 parts by mass or less of an organic solvent with respect to a total of 100 parts by mass of the coating composition. The composition contains (a) a first silicone emulsion having at least two alkenyl groups per molecule, (b) a second silicone emulsion having at least two hydrogen groups per molecule, and (d) a surfactant. The adhesion energy of the surface of the mold release layer as calculated from the sliding angle of water is at least 6.0 mJ/m². The tape release force of the surface of the mold release layer is at most 2000 mN/50 mm.

Description

Release film and its manufacturing method

The present invention relates to a release film having a base film and a release layer and a method for producing the same, and more particularly to a release film useful as a film for various processes and a method for producing the same.

Conventionally, release films, which are made of polyester film or the like as a base material and have a release layer laminated thereon, have high heat resistance and mechanical properties, and can be used as adhesive sheets, cover films, resin sheets such as ceramic green sheets and polymer electrolyte membranes. It is used as a process film for forming films. Further, as a release layer of a release film, many release layers formed from coating compositions containing silicone have been proposed because they have good heat resistance and peelability (for example, Patent Documents 1 to 5).

The release film is also used as a process film for molding ceramic green sheets that require high smoothness for laminated ceramic capacitors, ceramic substrates, etc. In recent years, as multilayer ceramic capacitors have become smaller and larger in capacity, the thickness of ceramic green sheets has also tended to become thinner. Ceramic green sheets are formed by applying a slurry containing a ceramic component such as barium titanate and a binder resin onto a release layer of a release film and drying the slurry. A multilayer ceramic capacitor is manufactured by printing electrodes on a molded ceramic green sheet and peeling it off from a release film, and then laminating, pressing, firing, and applying external electrodes to the ceramic green sheet with electrodes.

Patent Documents 1 and 2 disclose that a coating composition containing a polysiloxane having an unsaturated group, a polysiloxane having an Si-H group, a platinum group metal catalyst, etc., and an organic solvent is coated on one side of a biaxially stretched polyester. A release film has been proposed in which a release layer is formed by drying and curing the coating composition by heat treatment after application (hereinafter referred to as "off-line coating").

Patent Document 3 describes a method (hereinafter referred to as "in-line coating") in which an aqueous coating composition containing an alkenyl group-containing silicone and a Si-H group-containing silicone is applied to one side of a polyester film, and then the polyester film is stretched. ) has proposed a release film with a release layer formed thereon.
Further, Patent Document 4 proposes a release film using offline coating. Further, Patent Document 5 proposes a release film using in-line coating.

JP2003-292894 WO2017/200056 JP2010-17932 Patent No. 6619200 JP2021-11081

In recent years, as ceramic green sheets have become thinner, there is a tendency for release films to have easy peelability that allows the ceramic green sheets to be peeled off with a low and uniform force. There is also a need for a release film that has good wettability with respect to the ceramic slurry applied onto the release layer. In order to form a ceramic green sheet into a thin film, it is required, for example, to use an organic solvent in an amount equal to or greater than the amount of resin to uniformly apply a diluted ceramic slurry with a low solid content concentration onto the mold release layer. When a ceramic slurry made of such a composition is applied to a mold release layer, the wettability of the release film to the ceramic slurry may be insufficient, and slight repellency or uneven coating that occurs during application may cause the ceramic There was a risk that pinholes or thickness unevenness would occur in the green sheet, and the yield of multilayer ceramic capacitors would deteriorate.
As a result of extensive studies, the present inventors found that in the release layer formed by applying an aqueous coating composition, reacting it, and solidifying it, the organic solvent contained in the composition also affects the physical properties of the release layer. I found out what it can do.
Specifically, organic solvents impair the stability of the water-dispersed emulsion contained in the aqueous coating composition, impairing the uniformity of the release layer formed by the composition, and deteriorating releasability. there were.
Furthermore, as the amount of organic solvents used increases, there is a problem of increased toxicity to the human body and increased environmental burden.

In Patent Documents 1 and 2, in particular, there was a demand for further compatibility between easy peelability and good wettability of thin-layer ceramic green sheets. In addition, since the coating composition contains an organic solvent as its main component, it may have an adverse effect on the human body due to contact with the organic solvent or inhalation of its vapor, and may be harmful to the global environment due to the vapor of the organic solvent being released into the atmosphere. load was a problem.
In addition, the drying equipment for organic solvents must be explosion-proof, which requires initial installation costs, and requires a large amount of energy to operate, resulting in large CO2 emissions and a large environmental impact. was.

In Patent Document 3, the release layer is formed of a coating composition using a mixed solvent of water and isopropyl alcohol, which poses problems in that it is harmful to the human body and has a large environmental burden.
In addition, alcoholic solvents such as isopropyl alcohol may impair the stability of water-dispersed emulsions, impair coating uniformity due to agglomeration or gelation of the emulsion, and cause coating defects such as coarse protrusions and cissing caused by agglomerates. The problem was that this occurred. In particular, when forming a release layer using silicone that has excellent releasability, it is necessary to use emulsified silicone because silicone is generally insoluble in water. There was an issue in manufacturing the mold film.

Since the release film described in Patent Document 4 contains an organic solvent as a main component in the composition forming the release layer, it has the problem of being harmful to the human body and having a large environmental burden, as described above. In addition, there is a risk that the biaxially stretched polyester film as a base material may be deformed by the heat generated during drying and curing of the coating composition, so it was necessary to manufacture at a relatively low temperature.
In the invention of Patent Document 4, as described in the Examples, the coating composition was cured with heat of 135° C., and there was a risk that the amount of heat for curing the release layer would be insufficient. If the mold release layer is insufficiently cured, the solvent resistance of the mold release layer will be impaired, and the force required to peel off the ceramic green sheet will increase, causing damage to the ceramic green sheet during peeling and potentially causing defects. was there.

Since the release film described in Patent Document 5 uses an aqueous coating composition, coating defects such as repellency may occur when the aqueous coating composition is applied onto the polyester film or during the drying process. . In addition, since a water-dispersed emulsion is used, the emulsion is destroyed by shearing and heat during coating, and gels and aggregates are mixed into the release layer, causing uneven thickness of the release layer and coarse protrusions. There was a risk of causing coating defects such as omissions. The appearance of these coats may have an adverse effect on the releasability of the ceramic green sheet. In-line coatings also need to be produced at relatively high temperatures due to stretching and oriented crystallization of the polyester film. Therefore, although the curing of the mold release layer progresses more easily than in offline coating, resulting in a mold release layer with excellent releasability, there was a risk that the wettability of the ceramic slurry would be insufficient.

The present invention was made against the background of such problems of the prior art. In other words, it is possible to reduce the amount of organic solvents that are harmful to the human body and have a negative effect on the environment, and it also achieves both easy peelability and good wettability of thin resin sheets, especially thin ceramic green sheets. The purpose of the present invention is to provide a release film and a method for manufacturing the same.

As a result of intensive studies to solve the above problems, the present inventors have discovered that the above objects can be achieved by a release film having the following configuration and a method for manufacturing the same, and have completed the present invention.

That is, the present invention has the following configuration.
[1]
A release film having a polyester film and a release layer in this order,
The release layer is a layer formed by reacting and solidifying an aqueous coating composition,
The aqueous coating composition contains an organic solvent in an amount of 10 parts by mass or less based on 100 parts by mass of the total amount of the aqueous coating composition,
The aqueous coating composition comprises:
(a) a first silicone emulsion containing at least two or more alkenyl groups in one molecule;
(b) a second silicone emulsion containing at least two or more hydrogen groups in one molecule, and
(d) In the release layer containing a surfactant,
The adhesion energy of the surface of the release layer calculated from the sliding angle of water is 6.0 mJ/m ² or more,
A release film with a tape peeling force of 2000mN/50mm or less measured by the following method;
After the release film was immersed in toluene for 15 minutes and air-dried, an adhesive tape was laminated on the release layer and the release film with the tape was pressed under a load of 5 kg. After holding the release film with the tape at 70°C for 20 hours, The tape peeling force is measured by T-shaped peeling at a peeling speed of 0.3 m/min.
[2]
The aqueous coating composition is
(c) The release film according to [1] [3] containing an aqueous dispersion containing silicone having a Q unit represented by SiO _4/2
In the aqueous coating composition,
(a) the first silicone emulsion containing at least two or more alkenyl groups in one molecule has a number average molecular weight of 1,000 or more and less than 30,000;
(b) The release film according to [1] or [2], wherein the second silicone emulsion containing at least two or more hydrogen groups in one molecule has a number average molecular weight of 1,000 to 10,000.
[4]
The release film is obtained by applying the aqueous coating composition to the base film before the crystal orientation is completed, stretching in at least one direction, and then heat-treating the base film to complete the crystal orientation of the base film. The release film according to any one of [1] to [3], which is formed.
[5]
The release film according to any one of [1] to [4], wherein the polyester film has a surface layer substantially free of inorganic particles, and the release layer is formed on the surface layer.
[6]
The release film according to any one of [1] to [5], wherein the release film is a release film for manufacturing a multilayer ceramic capacitor or a resin sheet.
[7]
A method for producing a release film, or a method for producing a release film according to any one of [1] to [6], comprising the following steps;
A coating step of applying an aqueous coating composition to at least one side of a polyester film, the coating step comprising:
The aqueous coating composition contains an organic solvent in an amount of 10 parts by mass or less based on 100 parts by mass of the total amount of the aqueous coating composition,
Contains water, a water-soluble component and/or a water-dispersed emulsion,
a coating step in which the surface tension of the aqueous coating composition is 40 mN/m or less; and
a heating step of heating the polyester film coated with the aqueous coating composition;
[8]
The aqueous coating composition comprises:
(A) a first silicone emulsion containing at least two or more alkenyl groups in one molecule;
(B) a second silicone emulsion containing at least two or more hydrogen groups in one molecule, and
(D) Contains a surfactant;
the coating step using the aqueous coating composition in which the surfactant has a boiling point of 200° C. or higher;
The method for producing a release film according to [7].
[9]
The method for producing a release film according to [7] or [8], wherein the heating step includes the following steps, and the heating step is performed after the coating step;
a drying step of drying the aqueous coating composition applied to one side of the polyester film;
a stretching step of stretching in a direction perpendicular to the longitudinal direction of the polyester film; and
A heat setting step of heat-treating the polyester film to complete crystal orientation.
[10]
In the coating step, the liquid temperature of the aqueous coating composition is 0°C or more and 40°C or less,
The method for producing a release film according to any one of [7] to [9], wherein the maximum temperature in the heating step is 180°C or higher and 250°C or lower.
[11]
The method for producing a release film according to any one of [7] to [10], for producing a release film for producing a resin sheet or a multilayer ceramic capacitor.

The release film of the present invention can improve the releasability and wettability of the release layer, and can further suppress the occurrence of defects in thin resin sheets, especially ceramic green sheets.
Furthermore, the toxicity to the human body and the environmental load during the manufacturing process can be reduced. Moreover, a uniform release layer can be formed without fear of impairing the stability of the first silicone emulsion and the second silicone emulsion contained in the aqueous coating composition.

Since the present invention has the features described in this specification, it can further solve the problems described below and produce effects.
In particular, it is possible to achieve both easy peelability and good wettability of the thin ceramic green sheet. Furthermore, compared to a coating composition containing an organic solvent as a main component, the amount of organic solvent can be greatly reduced or it can be substantially eliminated. As a result, it is possible to greatly reduce the adverse effects on the human body due to contact with the organic solvent and inhalation of its vapor, and the burden on the global environment due to the emission of organic solvent vapor into the atmosphere.
Furthermore, there is no need to make the organic solvent drying equipment explosion-proof equipment, and energy consumption during operation can be reduced compared to conventional manufacturing equipment. Therefore, CO2 emissions can be reduced, and the environmental burden can be reduced.

Further, according to the present invention, since aggregation and gelation of the emulsion can be suppressed, coating uniformity is excellent, and the reduction of coarse protrusions derived from aggregates and the occurrence of coating defects such as repellency can be suppressed in a well-balanced manner. Moreover, a release film exhibiting easy releasability can be obtained.
In addition, with the present invention, the reaction and solidification of the coating composition and the stretching and crystallization of the polyester film can proceed at the same time, while suppressing thermal deformation of the polyester film that is the base material compared to conventional methods. , the release layer can be cured at high temperatures.
Moreover, since the mold release layer can be sufficiently cured, the mold release layer has excellent solvent resistance. Furthermore, for example, it is possible to suppress an increase in force when peeling the ceramic green sheet, reduce damage to the ceramic green sheet during peeling, and prevent the occurrence of defects.

Furthermore, with the present invention, when an aqueous coating composition is applied onto a polyester film, coating defects such as repellency can be suppressed during the drying process, and uneven thickness of the release layer, generation of coarse protrusions, etc. can be suppressed. Coating defects such as coating defects can be suppressed.
For example, according to the present invention, in an embodiment in which a release film is manufactured using an in-line coating method, a release layer with excellent hardening and peelability can be formed, and ceramic slurry, which has been considered difficult in the past, can be formed. It is also possible to obtain the required physical properties regarding wettability.

The present invention is a release film having a release layer on at least one surface of a polyester film. For example, the present invention provides a release film having a polyester film and a release layer in this order,
The release layer is a layer formed by reacting and solidifying an aqueous coating composition,
The aqueous coating composition comprises:
Containing an organic solvent in an amount of 10 parts by mass or less based on 100 parts by mass of the total coating composition,
The composition includes:
(a) a first silicone emulsion containing at least two or more alkenyl groups in one molecule;
(b) a second silicone emulsion containing at least two or more hydrogen groups in one molecule;
(d) Surfactant
including;
In the release layer,
A release film having an adhesion energy on the surface of the release layer calculated from the sliding angle of water of 6.0 mJ/m ² or more and a tape peeling force of 2000 mN/50 mm or less as measured by the following method;
On the release layer of the release film that was air-dried after being immersed in toluene for 15 minutes,
The tape-attached release film obtained by laminating adhesive tape and pressing with a 5 kg load is held at 70°C for 20 hours, and then the tape peeling force is measured by T-shaped peeling at a peeling speed of 0.3 m/min.

The present invention having such a configuration can achieve both easy releasability and good wettability of the release layer, and can provide a uniform thickness without defects to a thin resin sheet, such as a thin ceramic green sheet. can be provided, and defects such as pinholes can be suppressed.
Further, the present invention can have the following effects. In the present invention, an aqueous coating composition with a significantly reduced amount of organic solvent compared to conventional ones or an aqueous coating composition containing substantially no organic solvent is used, so there is less harm to the human body and less environmental burden, and there is less CO ² It is possible to produce a release film while suppressing the occurrence of .

Furthermore, in one embodiment, the release film of the present invention achieves both releasability and wettability by applying an aqueous coating composition having a predetermined composition using an in-line coating method to form a release layer. be able to. More specifically, since a thermosetting silicone emulsion can be heat-cured in a relatively high-temperature environment, it exhibits excellent releasability. In in-line coating, the base film is stretched and crystallized at the same time as the release layer is formed, so even if heat is applied at relatively high temperatures, specifically over 180°C, the film does not deform or shrink due to heat. , it is possible to produce a release film with excellent flatness.
In addition, since an aqueous coating composition containing a surfactant is used, when the coating composition is applied onto a polyester film to form a mold release layer, there are no coating defects such as repellency, and the mold release has excellent releasability. It becomes a layer.
Furthermore, since the stability of the silicone emulsion is increased, there is no fear that coarse protrusions or uneven thickness of the release layer will occur due to aggregation or gelation of the emulsion. In general, surfactants exhibit amphiphilic properties that are soluble in organic solvents and water, so they have poor solvent resistance to organic solvents in ceramic slurries and may cause an increase in peeling force. By curing the mold layer, it is possible to create a release layer with a high crosslinking density and excellent solvent resistance, making it possible to produce a release film that exhibits easy releasability and good wettability, which was previously difficult. .

The wettability of the release film of the present invention can be evaluated by adhesion energy calculated from the sliding angle measured by forming a droplet on the release layer. The solvent that forms the liquid droplet is not limited when evaluating the adhesion energy, but it is preferably calculated from the sliding angle of water in order to facilitate evaluation of the amount of surfactant contained in the release layer. The detailed evaluation method will be described later.

The releasability of the release film of the present invention can be evaluated by the tape peeling force after the release film is immersed in toluene. For the releasability of a resin sheet, such as a ceramic green sheet, the solvent resistance of the release layer to the organic solvent contained in the ceramic slurry applied on the release layer is important. Therefore, by using the tape peeling force after immersing the release film in an organic solvent, for example, toluene, we can simultaneously evaluate the peeling force and solvent resistance for various objects to be peeled, such as resin sheets and ceramic green sheets. It is possible and preferred.
As a method for evaluating whether the present invention has excellent solvent resistance and peeling force, the following tape peeling force test after toluene immersion treatment can be mentioned.
The tape peeling force in the present invention can be evaluated using a commercially available adhesive tape. For example, the strength of a release film with a tape obtained by laminating an adhesive tape onto a release layer and pressing it under a 5 kg load is shown when the tape is peeled off after being held in an environment of 70°C for 20 hours. The detailed evaluation method will be described later.
As the adhesive tape, an acrylic adhesive tape can be used, and a general-purpose adhesive tape such as No. 31B manufactured by Nitto Denko Corporation can be used.

In another aspect, the present invention provides a method for producing a release film, which includes the following steps.
A coating step of applying an aqueous coating composition to at least one side of a polyester film, the coating step comprising:
The aqueous coating composition contains 10 parts by mass or less of an organic solvent based on 100 parts by mass of the total amount of the coating composition, and preferably contains substantially no organic solvent.
Contains water, a water-soluble component and/or a water-dispersed emulsion,
A coating process in which the surface tension of the aqueous coating composition is 40 mN/m or less;
a heating step of heating the polyester film coated with the aqueous coating composition;

In the manufacturing method according to the present invention, by setting the manufacturing conditions particularly when forming the mold release layer to a predetermined method, a mold release layer with excellent releasability and wettability can be formed.
For example, the molecular structure of the silicone emulsion contained in the aqueous coating composition, the molecular weight of the surfactant, the surface tension of the aqueous coating composition, the coating amount of the aqueous coating composition, the liquid temperature of the aqueous coating composition, and the temperature of the heating process. Examples include.
By producing a release film under the conditions of the present invention, the crosslinking density of the cured film of thermosetting silicone forming the release layer increases, solvent resistance improves, and easy releasability is exhibited. Since the surfactant remains in the mold release layer and segregates on the surface of the release layer, a release film with excellent wettability can be obtained. Details will be described later.

(Polyester film)
The polyester constituting the polyester film used as the base film is not particularly limited, and a film formed from a polyester commonly used as a base material for a release film can be used. Preferably, it is a crystalline linear saturated polyester consisting of an aromatic dibasic acid component and a diol component, such as polyethylene terephthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, polytrimethylene terephthalate, or a combination of these resins. More preferred are copolymers containing the constituent components as main components. In particular, polyester films formed from polyethylene terephthalate are particularly suitable. In polyethylene terephthalate, the repeating units of ethylene terephthalate are preferably 90 mol% or more, more preferably 95 mol% or more, and a small amount of other dicarboxylic acid components and diol components may be copolymerized. For example, from the viewpoint of cost, it is preferable to use one made from only terephthalic acid and ethylene glycol. Further, known additives such as antioxidants, light stabilizers, ultraviolet absorbers, crystallizing agents, etc. may be added within a range that does not impede the effects of the release film of the present invention. The polyester film is preferably a biaxially oriented polyester film for reasons such as high elastic modulus in both directions.

The intrinsic viscosity of the polyester film is preferably 0.50 dl/g or more and 0.70 dl/g or less, more preferably 0.52 dl/g or more and 0.62 dl/g or less. When the intrinsic viscosity is 0.50 dl/g or more, it is preferable because many breaks do not occur during the stretching process. On the other hand, if it is 0.70 dl/g or less, it is preferable because the cutting properties are good when cutting into a predetermined product width and dimensional defects do not occur. Further, it is preferable that the raw material pellets be sufficiently vacuum dried.

In addition, in this specification, when it is simply described as a "polyester film", it means a polyester film having (laminated) a surface layer A and a surface layer B.

The method for producing the polyester film in the present invention is not particularly limited, and conventionally commonly used methods can be used. For example, it can be obtained by melting the polyester in an extruder, extruding it into a film, cooling it in a rotating cooling drum to obtain an unstretched film, and then biaxially stretching the unstretched film. A biaxially stretched film can be obtained by sequentially biaxially stretching a uniaxially stretched film in the longitudinal or transverse direction in the transverse or longitudinal direction, or by simultaneously biaxially stretching an unstretched film in the longitudinal and transverse directions. I can do it.

In the present invention, the stretching temperature during stretching of the polyester film is preferably at least the secondary transition point (Tg) of the polyester. It is preferable to stretch the film by a factor of 1 to 8 times, particularly 2 times to 6 times, in both the longitudinal and transverse directions.

The thickness of the polyester film is preferably 12 μm or more and 50 μm or less, more preferably 15 μm or more and 38 μm or less, and even more preferably 19 μm or more and 33 μm or less. If the thickness of the film is 12 μm or more, there is no risk of deformation due to heat during film production, processing, and molding, which is preferable. On the other hand, if the thickness of the film is 50 μm or less, the amount of film to be discarded after use will not be excessively large, which is preferable in terms of reducing environmental burden.

The polyester film base material may be a single layer or a multilayer of two or more layers. For example, the base film may be a polyester film having a surface layer A that does not substantially contain particles having a particle size of 1.0 μm or more and a surface layer B that contains particles. Preferably, surface layer A does not substantially contain inorganic particles having a particle size of 1.0 μm or more.

In this embodiment, particles having a particle size of less than 1.0 μm and 1 nm or more may be present in the surface layer A. Since the surface layer A does not substantially contain particles having a particle size of 1.0 μm or more, for example, inorganic particles, it is possible to reduce problems caused by transfer of the shape of particles in the base material to the resin sheet.

In one embodiment, the surface layer A does not contain particles with a particle size of less than 1.0 μm, so that problems caused by transfer of the particle shape in the base material to the resin sheet can be more effectively suppressed.
In one embodiment, the polyester film base material is preferably a laminated film having a surface layer A substantially free of inorganic particles on at least one side. Thereby, it is possible to more effectively suppress the transfer of the particle shape in the base material to the resin sheet and the occurrence of defects.
For example, it is preferable that the surface layer A that does not substantially contain particles with a particle size of less than 1.0 μm also substantially does not contain particles with a particle size of 1.0 μm or more.

Here, in the present invention, "contains substantially no particles" means, for example, in the case of inorganic particles less than 1.0 μm, the amount of inorganic elements determined by X-ray fluorescence analysis is 50 ppm or less, preferably 10 ppm or less. , most preferably means a content below the detection limit. Even if particles are not actively added to the film, contaminants derived from foreign substances or dirt attached to the raw resin or the line or equipment in the film manufacturing process are peeled off and mixed into the film. This is because there is. Further, "substantially not containing particles with a particle size of 1.0 μm or more" means that particles with a particle size of 1.0 μm or more are not included.

In the case of a laminated polyester film having a multilayer structure of two or more layers, it is preferable to have a surface layer B that can contain inorganic particles on the opposite side of the surface layer A that does not substantially contain inorganic particles.

Assuming that the layer on which the release layer is applied is layer A, the layer on the opposite side is layer B, and the other core layer is layer C, the layer structure in the thickness direction is release layer/A/ B, or a laminated structure such as release layer/A/C/B. Naturally, the C layer may have a plurality of layers. Furthermore, the surface layer B may not contain inorganic particles. In that case, it is preferable to provide a coating layer containing at least inorganic particles and a binder on the surface layer B in order to provide slipperiness for winding up the film into a roll.

In the polyester film base material of the present invention, the surface layer B forming the opposite surface to the surface to which the release layer is applied preferably contains inorganic particles from the viewpoint of the slipperiness of the film and the ease with which air can escape. In particular, it is preferable to use silica particles and/or calcium carbonate particles. The total amount of inorganic particles contained in the surface layer B is preferably 5,000 ppm or more and 15,000 ppm or less.

At this time, the area surface average roughness (Sa) of the film of the surface layer B is preferably in the range of 1 nm or more and 40 nm or less. More preferably, the range is 5 nm or more and 35 nm or less. When the total amount of silica particles and/or calcium carbonate particles is 5000 ppm or more and Sa is 1 nm or more, air can be released uniformly when the film is rolled up, resulting in a good rolled shape and good flatness. , it is suitable for producing ultra-thin ceramic green sheets. In addition, when the total amount of silica particles and/or calcium carbonate particles is 15,000 ppm or less and Sa is 40 nm or less, the lubricant is less likely to aggregate and coarse protrusions are not formed, resulting in stable quality when producing ultra-thin ceramic green sheets. It is preferable.

In addition to silica and/or calcium carbonate, inert inorganic particles and/or heat-resistant organic particles can also be used as particles contained in layer B, but from the viewpoint of transparency and cost, silica particles and/or More preferably, calcium carbonate particles are used. In addition, other inorganic particles that can be used include alumina-silica composite oxide particles, hydroxyapatite particles, and the like. Examples of the heat-resistant organic particles include crosslinked polyacrylic particles, crosslinked polystyrene particles, and benzoguanamine particles. In addition, when using silica particles, porous colloidal silica is preferable, and when using calcium carbonate particles, light calcium carbonate whose surface is treated with a polyacrylic acid-based polymer compound is preferable from the viewpoint of preventing the lubricant from falling off. .

The average particle diameter of the inorganic particles added to the surface layer B is preferably 0.1 μm or more and 2.0 μm or less, particularly preferably 0.5 μm or more and 1.0 μm or less. It is preferable that the average particle diameter of the inorganic particles is 0.1 μm or more because the release film has good slip properties. Further, if the average particle diameter is 2.0 μm or less, there is no possibility that the smoothness of the surface of the mold release layer will be adversely affected, and therefore there is no possibility that pinholes will occur in the ceramic green sheet, which is preferable.

From the viewpoint of reducing pinholes, it is preferable not to use recycled raw materials in the surface layer A, which is the layer on which the release layer is provided, in order to prevent inorganic particles such as lubricants from being mixed in.

The thickness ratio of the surface layer A, which is the layer on which the release layer is provided, is preferably 20% or more and 50% or less of the total layer thickness of the base film. If it is 20% or more, it is difficult to be affected by particles contained in the surface layer B etc. from inside the film, and it is easy for the area surface average roughness Sa to satisfy the above range, which is preferable. When the thickness is 50% or less of the total thickness of the base film, the ratio of recycled raw materials used in the surface layer B can be increased, and the environmental burden is small, which is preferable.

In addition, from the economic point of view, it is possible to use film scraps or recycled raw materials from PET bottles in an amount of 50% by mass or more and 90% by mass or less for layers other than the above-mentioned surface layer A (surface layer B or the above-mentioned intermediate layer C). can. Even in this case, it is preferable that the type and amount of lubricant contained in the B layer, the particle size, and the area surface average roughness (Sa) satisfy the above ranges.

In addition, in order to improve the adhesion of a later applied release layer, etc., and to prevent static electricity, the film is coated on the surface of the surface layer A and/or surface layer B before or after uniaxial stretching during the film forming process. A coating layer may be provided, and surface treatment etc. may also be performed.

In one embodiment, the release layer forming surface to which the aqueous coating composition is applied can be subjected to surface treatment or provided with an easy-to-adhesion layer in order to improve adhesion to the release layer. Surface treatments include plasma treatment, corona discharge treatment, ultraviolet treatment, flame treatment, and electron beam/radiation treatment.The adhesive layer contains the same resin as the base film, and further contains antistatic agents and pigments. , a surfactant, a lubricant, an anti-blocking agent, and the like. If an adhesion improver such as a coupling agent is added to the aqueous coating composition, the release layer should have sufficient adhesion to the base film even without providing an easy-adhesion layer. Can be done.

(Release layer)
In the present invention, the release layer is laminated on the surface layer A of the base film. In the present invention, the release layer is a layer formed by reacting and solidifying an aqueous coating composition,
The aqueous coating composition contains an organic solvent in an amount of 10 parts by mass or less based on 100 parts by mass of the total amount of the coating composition,
(a) a first silicone emulsion containing at least two or more alkenyl groups in one molecule;
(b) a second silicone emulsion containing at least two or more hydrogen groups in one molecule;
(d) a surfactant.
The release layer has an adhesion energy of 6.0 mJ/m ² or more calculated from the sliding angle of water,
A release film with a tape peeling force of 2000mN/50mm or less measured by the following method;
On the release layer of the release film that was air-dried after being immersed in toluene for 15 minutes,
Adhesive tape is laminated with a load of 5 kg, and after holding the release film with tape at 70°C for 20 hours, the tape peeling force is measured by T-shaped peeling at a peeling speed of 0.3 m/min.
Because the release layer has these characteristics, it is possible to provide a release film with excellent releasability and wettability, and it is possible to suppress the occurrence of defects such as pinholes on resin sheets and ceramic green sheets. , a sheet with uniform thickness can be formed.

More specifically, since the present invention forms the release layer by in-line coating, the release layer can be cured without impairing the flatness of the release film even in a relatively high-temperature environment of 180° C. or higher. Therefore, it is possible to form a release layer with a higher crosslinking density than when a release layer is formed by conventional off-line coating, and it can have easy releasability.
Further, according to the present invention, a release layer containing a surfactant soluble in water and an organic solvent can be manufactured, and can have excellent wettability when molding a sheet of ceramic slurry or the like. Furthermore, the stability of the silicone emulsion forming the release layer can be improved, and a release film having a uniform release layer without coating defects can be obtained.

The aqueous coating composition forming the release layer contains 10 parts by mass or less of an organic solvent based on 100 parts by mass of the total coating composition.
When the amount of organic solvent contained in the composition meets the above conditions, it is possible to greatly reduce the amount of organic solvent, or to substantially eliminate the amount of organic solvent, compared to a coating composition containing an organic solvent as a main component. . As a result, it is possible to greatly reduce the adverse effects on the human body due to contact with the organic solvent and inhalation of its vapor, and the burden on the global environment due to the emission of organic solvent vapor into the atmosphere.

In one aspect, the aqueous coating composition contains 0.01 parts by mass or more and less than 10 parts by mass of an organic solvent, for example 0.01 parts by mass or more and 8 parts by mass or less, based on 100 parts by mass of the total amount of the coating composition. .01 parts by mass or more and 5 parts by mass or less, 0.01 parts by mass or more and 3 parts by mass or less, 0.01 parts by mass or more and 1 part by mass or less, 0.01 parts by mass or more and less than 1 part by mass, 0.01 parts by mass or more and 0 .8 parts by mass or less. The amount of the organic solvent may be 0.01 part by mass or more and 0.5 parts by mass or less based on 100 parts by mass of the total resin solid content in the coating composition.
In one aspect, the aqueous coating composition may contain an organic solvent in an amount of 0.01 parts by mass or more and 0.2 parts by mass or less, for example, 0.01 parts by mass or more and 0.1 parts by mass or less. For example, the composition can be substantially free of organic solvents.
In the present invention, 100 parts by mass of the total amount of the coating composition can be defined as, for example, 100 parts by mass of the total amount of the aqueous coating composition applied to the base film before crystal orientation is completed.

In the present invention, by setting the amount of organic solvent to the above conditions, aggregation and gelation of the first silicone emulsion and the second silicone emulsion of the present invention can be suppressed, resulting in excellent coating uniformity and coarse particles originating from aggregates. It is possible to reduce protrusions and suppress the occurrence of coating defects such as repelling in a well-balanced manner. Moreover, a release film exhibiting easy releasability can be obtained.

Moreover, since the mold release layer can be sufficiently cured, the mold release layer has excellent solvent resistance. Furthermore, for example, it is possible to suppress an increase in force when peeling the ceramic green sheet, reduce damage to the ceramic green sheet during peeling, and prevent the occurrence of defects.
Furthermore, with the present invention, when an aqueous coating composition is applied onto a polyester film, coating defects such as repellency can be suppressed during the drying process, and uneven thickness of the release layer, generation of coarse protrusions, etc. can be suppressed. Coating defects such as coating defects can be suppressed.
For example, according to the present invention, in an embodiment in which a release film is manufactured using an in-line coating method, a release layer with excellent hardening and peelability can be formed, and ceramic slurry, which has been considered difficult in the past, can be formed. It is also possible to obtain the required physical properties regarding wettability.

Here, in the present invention, the organic solvent includes an organic solvent that is subject to the Organic Solvent Poisoning Prevention Regulations as a second type organic solvent (organic solvent). Examples of the second type organic solvent include acetone, isopropyl alcohol, ethyl ether, cellosolve, dichlorobenzene, xylene, cresol, ethyl acetate, methyl acetate, cyclohexanol, dioxane, dimethylformamide, toluene, n-hexane, butanol, methanol, Examples include methyl ethyl ketone.

In the present invention, the composition "substantially does not contain an organic solvent" refers to an amount of organic solvent in an amount of 0 parts by mass or more and less than 0.01 parts by mass, based on 100 parts by mass of the total amount of the aqueous coating composition. This means that the above organic solvents are included. This is because organic solvents may be contained in contaminant components derived from foreign substances, raw resins, additives, etc. even if organic solvents are not actively added.

(a) The first silicone emulsion having at least two or more alkenyl groups in one molecule is an aqueous dispersion obtained by emulsifying silicone containing at least two or more alkenyl groups in one molecule. . The silicone containing at least two or more alkenyl groups in one molecule may be any compound having a siloxane bond in the main chain, but polyorganosiloxanes having alkenyl groups in the terminal and/or side chains may be used. is preferred, and polydimethylsiloxane is more preferred. It is preferable that one molecule has 2 or more alkenyl groups and 20 or less alkenyl groups. The presence of two or more alkenyl groups results in a release layer with high crosslinking density when thermally cured, and exhibits easy releasability.

Examples of the silicone having an alkenyl group include a structure represented by the following general formula (I).

(In general formula (I), R ¹ may be the same or different and is an alkenyl group having 2 to 8 carbon atoms, or a monovalent hydrocarbon having 1 to 16 carbon atoms containing an alkyl group or an aryl group. At least two of R ¹ are alkenyl groups having 2 to 8 carbon atoms, and one or more of R ¹ bonded to the silicon atom represented by [SiO] _b1 is an alkenyl group having 2 to 8 carbon atoms. It is an alkenyl ^group.R2 may be the same or different and is a monovalent hydrocarbon group having 1 to 16 carbon atoms containing an alkyl group or an aryl group, and when a1+b1 is 100 mol%, a1 is 90 mol% or more and 100 mol% or less, and b1 is 0 mol% or more and 10 mol% or less.)
[SiO] R ² bonded to the silicon atom represented by _a1 may be a monovalent hydrocarbon group including an alkyl group or an aryl group, but may be a monovalent hydrocarbon group having 1 to 16 carbon atoms selected from an alkyl group or an aryl group. It is preferably a monovalent hydrocarbon group, more preferably a methyl group or a phenyl group, and even more preferably a methyl group. Furthermore, as exemplified by general formula (I), silicone having a D unit structure represented by SiO _2/2 is preferable.

R ¹ bonded to the silicon atom represented by [SiO] _b1 may be an alkenyl group having 2 to 8 carbon atoms, or a monovalent hydrocarbon group containing an alkyl group or an aryl group, but in [SiO] _b1 It is preferable that one or more of R ¹ bonded to the silicon atom shown is an alkenyl group having 2 or more and 8 or less carbon atoms. R ¹ is preferably a monovalent hydrocarbon group having 1 to 16 carbon atoms selected from an alkenyl group having 2 to 8 carbon atoms, an alkyl group, or an aryl group, and a methyl group or a phenyl group. is more preferred, and methyl group is even more preferred.

R ¹ at both ends is also the same as R ¹ bonded to the silicon atom shown in [SiO] _b1 , but the preferred structure is an alkenyl group having 2 to 8 carbon atoms, and the alkenyl group at the end is a hydrogen group. It is particularly preferable because steric structural hindrance becomes relatively small when the reaction occurs and peelability is easily improved.

Examples of the alkenyl group having 2 or more and 8 or less carbon atoms represented by R ¹ include a vinyl group, an allyl group, a butenyl group, a pentenyl group, a hexenyl group, and among these, a vinyl group is particularly preferred.

When the total structural units of [SiO] _a1 and [SiO] _b1 are 100 mol%, from the viewpoint of localizing hydrocarbon groups on the coating surface to improve releasability, [SiO] _a1 is The range of the structural unit is preferably 90 mol% or more and 100 mol% or less, and more preferably 92 mol% or more and 100 mol% or less.

The number average molecular weight of the silicone having an alkenyl group is preferably 1,000 or more and less than 30,000, more preferably 3,000 or more and less than 15,000. When the number average molecular weight is 1000 or more, hydrocarbon groups are localized on the coating surface, making it easy to obtain sufficient releasability. On the other hand, when the number average molecular weight is less than 30,000, the emulsifying property of the aqueous coating composition tends to be good and the uniform coating properties also tend to be good. Note that the number average molecular weight in the present invention refers to the value calculated from the integral ratio of the peaks derived from each siloxane unit after identifying the siloxane units from the peaks observed by ¹ H NMR and ²⁹ Si NMR.

(b) The second silicone emulsion having at least two or more hydrogen groups in one molecule is an aqueous dispersion obtained by emulsifying silicone having at least two or more hydrogen groups in one molecule. be. The silicone having at least two or more hydrogen groups in one molecule may be any compound having a siloxane bond in the main chain, but polyorganosiloxanes having hydrogen groups in the terminal or side chain may be used. Preferably, polydimethylsiloxane is more preferable. The terminal silicon atom may have a hydrogen group, but preferably has a trialkylsilane structure such as trimethylsilane. It is preferable that one molecule has 2 or more and 100 or less hydrogen groups. By having two or more hydrogen groups, it becomes a release layer with high crosslinking density when cured, and exhibits easy releasability.

As the silicone having a hydrogen group, a structure represented by the following general formula (II) is exemplified.

(In general formula (II), R ³ may be the same or different and is a monovalent hydrocarbon group having 1 to 16 carbon atoms and containing an alkyl group or an aryl group, and a2+b2 is 100 mol%. (In this case, a2 is 30 mol% or more and 90 mol% or less, and b2 is 5 mol% or more and 70 mol% or less.)
[SiO] A hydrogen atom (hydrogen group) is bonded to the silicon atom represented by _a2 , and ^R3 may be a monovalent hydrocarbon group including an alkyl group or an aryl group; It is preferable that it is a monovalent hydrocarbon group having 1 or more and 16 or less carbon atoms selected from the following. Further, as exemplified by general formula (II), silicone having a D unit structure represented by SiO _2/2 is preferable.

[SiO] _b2 and ^R3 bonded to the terminal Si atom may be any monovalent hydrocarbon group containing an alkyl group or an aryl group, but are selected from alkyl groups and aryl groups having 1 to 16 carbon atoms. The following monovalent hydrocarbon groups are preferred.

For any R ³ , it is more preferable that the number of carbon atoms in the alkyl group or aryl group is smaller, so that steric structural hindrance becomes relatively small and the crosslinking reaction progresses easily. It is also preferable from the viewpoint of the fluidity of the coating liquid in the coating process and the uniformity of the reaction structure in the release layer. Therefore, the alkyl group is preferably a methyl group, ethyl group, propyl group, butyl group, etc., and the aryl group is preferably a phenyl group, tolyl group, etc.

When the sum of the structural units of [SiO] _a2 and [SiO] _b2 is 100 mol%, the range of the structural unit of [SiO] _a2 is preferably from 30 mol% to 90 mol%, and from 40 mol% to 80 mol%. The following are more preferred. [SiO] When _{the a2} structural unit is 30 mol% or more, there will be a sufficient amount of crosslinking reaction points, the crosslinking density of the mold release layer will increase, and the scratch resistance and solvent resistance of the mold release layer will also be good. preferable. In addition, when the structural unit of [SiO] _a2 is 90 mol% or less, hydrogen groups are less likely to remain in the release layer, and the amount of uncrosslinked components in the release layer is less likely to increase, resulting in good releasability. Therefore, it is preferable.

The number average molecular weight of the hydrogen group-containing silicone in the present invention is preferably 1,000 or more and 10,000 or less, more preferably 3,000 or more and 8,000 or less. When the number average molecular weight is 1000 or more, sufficient releasability can be easily obtained. On the other hand, when the number average molecular weight is 10,000 or less, the emulsifying property to the aqueous coating composition tends to be good and the coating uniformity tends to be good as well. In addition, the crosslinking reaction is facilitated to proceed efficiently, the number of hydrogen groups remaining in the release layer is reduced, and the releasability is improved. Note that the number average molecular weight in the present invention refers to the value calculated from the integral ratio of the peaks derived from each siloxane unit after identifying the siloxane units from the peaks observed by ¹ H NMR and ²⁹ Si NMR.

The aqueous coating composition of the present invention preferably contains (c) an aqueous dispersion containing silicone having a Q unit represented by SiO _4/2 . (c) An aqueous dispersion containing silicone having a Q unit represented by SiO _4/2 is one in which silicone having the structure is dispersed in water as an emulsion or colloid. The silicone having this structure may have any structure as long as it is a compound having a siloxane bond in the main chain, but polyorganosiloxane having an alkenyl group at the terminal and/or side chain is preferable. Further, a copolymer containing a dialkylsiloxane unit or an alkylphenylsiloxane unit is preferable because the amount of alkenyl groups in one molecule can be easily adjusted while exhibiting releasability. The terminal silicon atom preferably has an alkenyl group, but may have a trialkylsilane structure such as trimethylsilane.

As the silicone having a Q unit represented by SiO _4/2 , a structure represented by the following formula (III) is exemplified.
R1 _a R2 _b SiO _(4-ab)/2 ...(III)
(In formula (I), R1 is an alkenyl group having 2 to 8 carbon atoms, R2 is a monovalent saturated hydrocarbon group having 1 to 16 carbon atoms selected from an alkyl group or an aryl group, and a is 0 to 3 , b is an integer between 0 and 3 and satisfies a+b≦3.)

Examples of the alkenyl group having 2 to 8 carbon atoms represented by R1 include a vinyl group, an allyl group, a butenyl group, a pentenyl group, a hexenyl group, and among these, a vinyl group is particularly preferred. Furthermore, examples of the alkyl group represented by R2 include a methyl group, ethyl group, propyl group, butyl group, and examples of the aryl group include a phenyl group and tolyl group. It is preferable that (c) contains an alkenyl group having 2 to 8 carbon atoms, represented by R1, from the viewpoint of reactivity with a hydrogen group. It is preferred because of its excellent properties, and a vinyl group having 2 carbon atoms is most preferred. It is preferable that 50 mol% or more of the substituents for R2 be methyl groups from the viewpoint of easy removability.

Silicones having Q units can have a structure in which the siloxane bonds are extended three-dimensionally, and therefore the alkenyl groups in the molecule can also exist extended three-dimensionally. Therefore, by reacting the silicone having a hydrogen group with the alkenyl group in the molecule, a dense crosslinked structure can be formed, and a release layer with excellent solvent resistance can be obtained. Generally, as the ratio of D units represented by SiO _2/2 contained in the release layer increases, the siloxane bonds tend to form a helical structure.For example, in the case of polydimethylsiloxane, the siloxane bonds present in All two methyl groups are arranged on the outside of the molecular chain, making it hydrophobic. On the other hand, when the ratio of Q units contained in the release layer increases, the helical structure of the siloxane bonds formed from D units collapses, resulting in a decrease in hydrophobicity. Although it is not limited by theory, by using a release layer containing silicone having Q units, it is possible to develop easy releasability due to increased crosslinking density and to improve hydrophobicity due to the collapse of the helical structure of siloxane bonds. In other words, it is possible to achieve both excellent wettability.

(c) The content of silicone contained in the release layer in the aqueous dispersion containing silicone having a Q unit is (a) the silicone contained in the first silicone emulsion having an alkenyl group, and (b) the silicone contained in the first silicone emulsion having an alkenyl group. ) 10 parts by mass when the total amount of silicone contained in the second silicone emulsion having hydrogen groups and silicone contained in the aqueous dispersion containing silicone having (c) Q units is 100 parts by mass. The amount is preferably 80 parts by weight, more preferably 20 parts by weight to 70 parts by weight. If the amount is 10 parts by mass or more, the silicone having Q units breaks the helical structure of the silicone made up of D units contained in the release layer, resulting in a release layer with excellent wettability, which is preferable. If the amount is 80 parts by mass or less, the silicone having Q units does not destroy the helical structure of the silicone made of D units contained in the release layer too much, resulting in a release layer with excellent releasability, which is preferable.

The content of Si atoms contained in the Q unit is 0.05 to 60 mol%, preferably 0.1 to 55 mol%, based on the total Si atoms in the silicone having the Q unit represented by SiO _4/2 . , more preferably 1.0 to 50 mol%. When the content of Si atoms contained in the Q unit is 0.05 mol % or more, a structure in which the siloxane bonds are sufficiently extended in three dimensions is obtained, and the effect of increasing the crosslinking density is exhibited, which is preferable. If it is 60 mol% or less, even excessive wettability will not cause heavy peeling, which is preferable.

The silicone having Q units is preferably solid at room temperature. The fact that silicone containing Q units is a solid means that many Q unit structures exist as continuous bonds within the molecule, and the silicone has a rigid molecular skeleton and exhibits physical properties similar to glass. By making the release layer contain silicone with such a rigid molecular skeleton, the elastic modulus of the release layer increases, making it difficult to deform when peeling objects such as ceramic green sheets, and making it lightweight. This is preferable because it forms a release layer that exhibits releasability.

(b) The content of the silicone contained in the second silicone emulsion having a hydrogen group in the release layer is the same as that of (a) the silicone contained in the first silicone emulsion having an alkenyl group and (b) the silicone contained in the second silicone emulsion having a hydrogen group. When the total amount of the silicone contained in the second silicone emulsion having a Gen group and the silicone contained in the aqueous dispersion containing the silicone having a (c) Q unit is 100 parts by mass, 5 parts by mass to 50 parts by mass. Parts by mass are preferred. If the amount is 5 parts by mass or more, the crosslinking reaction points will proceed sufficiently, a dense crosslinked structure will be easily formed, and the peelability will be excellent, which is preferable. When the amount is 50 parts by mass or less, hydrogen groups in the release layer are less likely to remain, the surface activity of the release layer is less likely to increase, and releasability is maintained favorably, which is preferable.
In one embodiment, the content of silicone contained in (b) the second silicone emulsion having a hydrogen group contained in the composition is equal to the amount of silicone contained in the first silicone emulsion having (a) an alkenyl group. less than the content of.

The aqueous coating composition of the present invention preferably contains at least (d) a surfactant. Containing a surfactant is preferable because it provides excellent coatability when the coating composition is applied onto a polyester film as a base film, and there is no fear that coating defects such as repellency will occur. In addition, the stability of the emulsion present in the coating composition is not impaired, and there is no risk of contamination of aggregates or gelled substances of the coating composition into the release layer, which prevents unevenness of the release layer and uneven coating. This is preferable because it can be suppressed.

As the surfactant, known materials can be used without particular restrictions, but materials that can suppress the amount of surfactant volatilization during the heating process of stretching and crystallizing the base film and remain in the release layer. It is preferable to use It is preferable that the surfactant remains in the release layer because it increases the wettability with respect to ceramic slurry or the like in which an organic solvent is used.

As the surfactant, cationic, anionic, and nonionic surfactants can be suitably used, but it is preferable to use nonionic surfactants from the viewpoint of improving the stability of the emulsion. For example, alkylene oxide adducts of higher alcohols or higher fatty acids, esters of alkylene oxide adducts of higher fatty acids and alcohols, alkylene oxide adducts of alkanolamides, alkylene oxide adducts of sorbitan esters, and alkylene oxides of higher fatty acid glycerides. At least one type selected from alkylene oxide addition types such as adducts can be mentioned. The surfactant used preferably has an HLB value in the range of 6 to 18. Here, the HLB value is a value calculated using the Griffin calculation formula.

Examples of the alkylene oxide include ethylene oxide, propylene oxide, and butylene oxide, and one or more of these may be used. When a plurality of them are used, the HLB value is preferably in the range of 8 to 18, more preferably in the range of 10 to 15, although it does not matter whether the addition format is block or random. Among these nonionic emulsifiers, polyoxyethylene lauryl ether, polyoxyethylene tridecyl ether, and the like are preferably mentioned. If a nonionic emulsifier with an HLB value outside this range is used as an emulsifier for a silicone aqueous dispersion, the emulsifying dispersion power and stability of the aqueous dispersion may decrease.

As an example of the alkylene oxide used in the present invention, the structure shown in the following formula (IV) is exemplified.
H _2m+1 C _m -O-(CH ₂ -CH ₂ -O) _n -H (IV)
(In formula IV, m and n are integers from 1 to 30. The number m indicates the alkyl group chain length, and the number n indicates the number of moles of ethylene oxide added.)
The larger the number of m and the longer the alkyl group chain length, the better the lipophilicity and the better the stability of the aqueous silicone emulsion. Furthermore, the larger the number of n and the larger the number of ethylene oxides, the better the hydrophilicity and the higher the stability of the aqueous silicone emulsion, which is preferable. The number of m and the number of n can take any value in the range of 1 to 30, but the larger the molecular weight, the higher the molecular weight, and the interface between the heat curing process of the coating composition and the stretching and crystallization process of the base film. This is preferable because the activator remains in the release layer without volatilizing, resulting in a release film with excellent wettability.

In order for the surfactant to remain in the release layer, the number average molecular weight of the surfactant is preferably in the range of 200 to 2,000, more preferably in the range of 250 to 1,000. In one embodiment, the number average molecular weight of the surfactant is 380 or more and 800 or less.
When the number average molecular weight is 200 or more, the surfactant remains in the release layer without being volatilized during the heating curing process of the coating composition and the stretching and crystallization process of the base film, resulting in a mold release with excellent wettability. This is preferred because a film can be obtained. It is preferable that the number average molecular weight is 2000 or less because it does not deteriorate the stability of the emulsion or the coatability of the coating composition. Moreover, since the surfactant segregates on the surface of the mold release layer during the thermosetting process of the mold release layer, wettability is improved, which is preferable.

The boiling point of the surfactant is preferably 200°C or higher, more preferably 230°C or higher, and even more preferably 250°C or higher. If the boiling point of the surfactant is 200°C or higher, the surfactant will remain in the release layer without volatilizing during the heat curing process of the coating composition and the stretching and crystallization process of the base film, resulting in excellent wettability. It is preferable because it becomes a release layer. For example, the boiling point of the surfactant is 200°C or more and 350°C or less, and may be 200°C or more and 320°C or less. By having the boiling point of the surfactant within the above range, rapid volatilization of the surfactant during the drying and curing process of the release layer can be suppressed, and the adhesion energy calculated from the sliding angle can be lowered. It can be suppressed. Moreover, deterioration of wettability can also be suppressed.

The content of the surfactant contained in the coating composition is preferably 0.1 parts by mass to 20 parts by mass, and preferably 0.15 parts by mass to 15 parts by mass, based on the total amount of resin solids in the coating composition. It is more preferable that there be. A content of 0.1 part by mass or more is preferable because it provides excellent coating properties when applied onto a polyester film, and the surfactant remains in the release layer, resulting in excellent wettability. When the amount is 20 parts by mass or less, there is no possibility that too much residual surfactant will cause heavy exfoliation, which is preferable.
In the present specification, the total amount of resin solids in the coating composition includes (a) alkenyl group-containing silicone, (b) hydrogen group-containing silicone, and (C) Q unit-containing silicone added as necessary. Means the total amount of solids.

In the present invention, the surface tension of the aqueous coating agent is preferably 10 to 40 mN/m, more preferably 10 to 35 mN/m. When it is 10 mN/m or more, it is preferable because it levels when applied onto a base film, resulting in a uniform coating appearance with no streaks or the like. When it is 40 mN/m or less, the coating agent spreads easily on the base film, and the stability of the emulsion increases, which is preferable. Further, the amount of surfactant contained in the coating agent is a sufficient amount, and the surfactant remaining in the release layer after heat curing can improve the wettability of ceramic slurry, etc., which is preferable.

(Platinum-based catalyst)
The aqueous coating of the present invention requires the use of a platinum-based catalyst in order to cause an addition reaction between the silicone having an alkenyl group and the silicone having a hydrogen group. Known platinum catalysts can be used, such as platinum chloride and chloroplatinic acid. The platinum-based catalyst may be a 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum(0) complex (Karstedt catalyst) in consideration of its dispersibility in silicone. Uniform dispersibility can be ensured by dispersing at the same time.

The amount of the platinum-based catalyst forms the release layer (a) silicone contained in the first silicone emulsion having an alkenyl group, (b) silicone contained in the second silicone emulsion having a hydrogen group, (c) SiO It is preferable that the weight of elemental platinum is contained in the range of 10 to 800 ppm based on the total amount of silicone contained in the aqueous dispersion of silicone having Q units expressed by _4/2 . By setting it as this range, the silicone can be sufficiently cured, the generation of aggregates can be suppressed, and a release film with excellent smoothness can be obtained. It is preferable that the weight ratio of the platinum element is 800 ppm or less because there is no possibility that the addition reaction between the alkenyl group and the hydrogen group will be accelerated and silicone aggregates will be generated. The amount of platinum-based catalyst is more preferably 600 ppm or less, even more preferably 500 ppm or less, and even more preferably 300 ppm or less. Further, when it is 10 ppm or more, the silicone addition reaction proceeds efficiently, the release layer is sufficiently cured, and easy releasability is exhibited, which is preferable.

(reaction inhibitor)
The aqueous coating composition of the present invention preferably contains a reaction inhibitor in order to suppress the activity of the platinum-based catalyst at room temperature. The content of the reaction inhibitor is preferably 5 to 1000 ppm, more preferably 10 to 700 ppm, and preferably 20 to 500 ppm, based on the total weight of the aqueous coating composition. If it is 5 ppm or more, the effect of suppressing the activity of the platinum catalyst will be sufficient, which is preferable. If it is 1000 ppm or less, there is no risk that the inside of the oven will be contaminated by the reaction inhibitor that evaporates during heat treatment, which is preferable.

The aqueous coating composition of the present invention may further contain adhesion imparting agents, colorants, ultraviolet absorbers, particles, etc. within a range that does not impair the objectives of the present invention.

(Other features of release layer)
The thickness of the release layer in the present invention after drying is preferably 0.001 to 0.2 μm, more preferably 0.005 to 0.1 μm. A thickness of 0.001 μm or more is preferable because a release layer with excellent releasability can be obtained. If it is 0.2 μm or less, there is no need to increase the solid content concentration of the release layer component of the aqueous coating composition or the coating amount, and the coatability when coated onto the base film is excellent, which is preferable.

The release film of the present invention preferably has a tape peeling force of 2000 mN/50 mm or less, more preferably 1500 mN/50 mm or less, and even more preferably 1200 mN/50 mm or less after toluene immersion treatment. For example, it may be 1000 mN/50mm or less. The toluene immersion treatment in the present invention refers to a process in which the release film is left to stand and immersed in toluene for 15 minutes, and then the release film is air-dried for 3 hours to dry the toluene attached to the release film. By evaluating the tape peeling force of the release film after toluene immersion treatment, it is possible to evaluate the peeling force including the solvent resistance to the organic solvent used when molding a resin sheet, for example, a ceramic green sheet. If it is 2000 mN/50 mm or less, it becomes a release film with excellent solvent resistance and peelability, which is preferable. The lower the tape peeling force is, the better the peelability is, but realistically it is preferably 1 mN/50 mm or more. If it is 1 mN/50 mm, it is preferable because there is no risk that the molded resin sheet or ceramic green sheet will float during transportation and cause problems. Note that the tape peeling force in the present invention refers to a tape with a tape obtained by laminating, for example, an acrylic adhesive tape, such as Nitto Denko No. 31B tape, on the surface of the release layer and pressing it with a 5 kg load. The value obtained by sandwiching the release film between 750 g glass plates, holding the film in a 70°C environment for 20 hours, and then T-peeling the tape at a peeling speed of 0.3 m/min can be used.

The release film of the present invention preferably has a water adhesion energy of 6.0 mJ/m ² or more, and preferably 7.0 mJ/m ² or more, calculated from the sliding angle measured by creating a water droplet on the release layer. is more preferable, more preferably 8.0 mJ/m ² or more, may exceed 8.0 mJ/m ² , and most preferably the adhesion energy cannot be calculated without water droplets sliding down.
When the water adhesion energy is larger than 6.0 mJ/m ² , it is preferable because repelling is difficult to occur when forming a thin resin sheet, ceramic green sheet, etc., and a sheet with a uniform thickness without defects can be obtained.
Since it is considered that the wettability is so good that the adhesion energy is too large to be calculated if water droplets do not slide off, a release film that does not allow water droplets to slide off can also be suitably used.
In this specification, when water droplets do not slide down, it refers to a state in which water droplets do not immediately slide off when water droplets are attached to a release film and the release film is tilted up to 90°.

The water adhesion energy is 10 mJ/m ² or less, for example, 9.5 mJ/m ² or less, and may be 9.0 mJ/m ² or less. When the water adhesion energy is within the above range, it is preferable because repelling is less likely to occur when forming a thin resin sheet, ceramic green sheet, etc., and a sheet with a uniform thickness without defects can be obtained.
For example, the water adhesion energy is 6.0 mJ/m ² or more and 10 mJ/m ² or less, and may be 6.0 mJ/m ² or more and 9.0 mJ/m ² or less.

(Method for manufacturing release film)
In another embodiment, the present invention provides a method for producing a release film, which includes the following steps.
A coating step of applying an aqueous coating composition to at least one surface of a polyester film, the aqueous coating composition containing an organic solvent in an amount of 10 parts by mass or less based on 100 parts by mass of the total amount of the coating composition, Preferably, it does not substantially contain an organic solvent and contains water, a water-soluble component and/or a water-dispersed emulsion,
a coating step in which the surface tension of the aqueous coating composition is 40 mN/m or less;
a heating step of heating the polyester film coated with the aqueous coating composition;

With the manufacturing method of the present invention, by setting the surface tension of the aqueous coating composition to 40 mN/m or less, when coating it on a polyester film, there will be no coating defects such as repelling, streaks, or uneven coating, and the coating will be uniform and defective. It is possible to obtain a release film free of . In addition, by setting the surface tension to 40 mN/m or less, the stability of the silicone emulsion in the aqueous coating composition is increased, and aggregates and gelled substances are mixed into the release layer, which deteriorates the flatness of the release film. There is no fear and it is desirable. The surface tension is more preferably 35 mN/m or less, even more preferably 33 mN/m or less. In addition, the surface tension in this invention shows the value of the static surface tension measured by the pendant drop method.

The surface tension of the aqueous coating composition may be greater than or equal to 10 mN/m, and may be greater than or equal to 15 mN/m. When the surface tension exhibits such conditions, it is preferable because it levels when coated onto a base film, resulting in a uniform coating appearance without streaks or the like.
For example, the surface tension of the aqueous coating composition may be 10 mN/m or more and 40 mN/m or less, 10 mN/m or more and 33 mN/m or less, and 15 mN/m or more and 33 mN/m or less.

In the release film of the present invention, an aqueous coating composition is applied to a base film before crystal orientation is completed, stretched in at least one direction, and then heat treated to complete crystal orientation of the base film. It can be formed by

It is preferable that the drying step in the production method of the present invention further includes the following steps. a drying step of drying the aqueous coating composition applied to one side of the polyester film;
A stretching process in which the polyester film is stretched in a direction perpendicular to its longitudinal direction;
A heat setting process in which polyester film is heat treated to complete crystal orientation.

For example, in a drying step in which an aqueous coating composition is applied to one surface of a polyester film and then the applied film is dried, the drying temperature may be 60°C or higher and 140°C or lower, for example, 60°C or higher and 130°C or lower, or 60°C or higher and 125°C or lower.
A temperature of 60° C. or higher is preferable because the composition is not dried sufficiently, and there is no risk of the film breaking when the polyester film is stretched in the stretching step.A temperature of 140° C. or lower can prevent the composition from drying rapidly and can suppress the emulsion from coagulating or gelling, resulting in excellent coating uniformity, a reduction in coarse protrusions derived from coagulation, and a well-balanced suppression of the occurrence of coating defects such as repelling.
Furthermore, in the present invention, the amount of organic solvent can be significantly reduced or substantially eliminated, compared with coating compositions containing an organic solvent as a main component, which significantly reduces the adverse effects on the human body caused by contact with the organic solvent or inhalation of its vapor, and the burden on the global environment caused by the release of the vapor of the organic solvent into the atmosphere.
In addition, there is no need to use explosion-proof equipment for drying organic solvents, and energy consumption during operation is reduced compared to conventional manufacturing equipment, which reduces CO2 emissions and the environmental impact.

By having a stretching step after the drying step of drying the applied aqueous coating composition, the film temperature in the stretching step of the polyester film is sufficient, and there is no risk of breakage or uneven thickness of the release film in the stretching step, which is preferable. In the stretching step, after drying the water in the aqueous coating composition, it is preferable to heat the polyester film as the base material to a temperature equal to or higher than the glass transition temperature. The temperature is preferably 60°C or more and 150°C or less, and preferably 70°C or more and 150°C or less from the viewpoint of stretchability.
In one embodiment, the stretching step is performed at a higher temperature than the drying step.

In the production method of the present invention, it is preferable to include a heat setting step in which the stretched polyester film is heat-treated to complete crystal orientation in order to impart dimensional stability and mechanical properties to the release film. The temperature in the heat setting step is preferably as high as possible in order to promote crystallization of the polyester film and curing of the release layer, but it is preferably a temperature equal to or lower than the melting point of the polyester. Specifically, the temperature is preferably 180°C or higher and 250°C or lower, more preferably 200°C or higher and 240°C or lower. A temperature of 180° C. or higher is preferable because curing of the release layer will proceed sufficiently and the dimensional stability and mechanical properties of the polyester film will be sufficient. A temperature of 250° C. or lower is preferable because the crystals of the polyester film do not melt and a release film with excellent flatness can be obtained.
For example, such a heat fixing process is sometimes referred to as a heating process. The heating step may include multiple steps. Further, the maximum temperature in the heating step is preferably 180°C or more and 250°C or less.
The maximum temperature of the heating step may also be within the above numerical range.

In the coating step, the coating solution temperature of the aqueous coating composition is preferably 0°C or higher and 40°C or lower, more preferably 5°C or higher and 30°C or lower. A temperature of 0° C. or higher is preferable because there is no fear that the aqueous coating composition will solidify and the emulsion will be destroyed. When the temperature is 40° C. or lower, there is no risk that the emulsion in the aqueous coating composition will be broken by heat and contamination of aggregates or gelled materials, and the occurrence of irregularities and coating unevenness in the release layer can be suppressed, which is preferable.

The total content of (a), (b), (c), and (d) contained in the coating composition shall be 0.1 to 30% by mass as solid content based on the total weight of the coating composition. The amount is preferably 0.5 to 20% by weight, more preferably 1 to 15% by weight. It is preferable that the amount is 0.1% by mass or more because the thickness of the release layer is sufficient to exhibit releasability. When the amount is 20% by mass or less, there is no fear that the release layer will become thick and the amount of curing heat will be insufficient, and the film forming property during stretching of the base film is also excellent, which is preferable.

The coating amount of the aqueous coating composition is preferably 0.1 g/m ² or more and 10 g/m ² or less. If the coating amount is 10 g/m ² or less, liquid turbulence will be less likely to occur at the kissing area between the film and the gravure roll when applied using the gravure coating method, and a release layer with excellent smoothness will be obtained. Therefore, it is preferable. It is preferable that the coating amount is 0.1 g/m ² or more, since there is no fear that the uniformity of the release layer will be impaired due to coating failure due to repelling or the like.

The pH of the aqueous coating composition is preferably 1 to 7, more preferably 2 to 6. When the pH of the aqueous coating composition is 1 or more, there is no risk of corrosion of tanks, piping, etc. during the coating process, and there is no risk of adverse effects on the human body, which is preferable. It is preferable that the pH is 7 or less because the emulsion in the coating composition will be stable and the coating composition will be excellent.

Any known coating method can be applied to apply the above coating liquid, such as roll coating methods such as gravure coating method and reverse coating method, bar coating method such as wire bar coating method, die coating method, spray coating method, and air knife coating method. Conventionally known methods such as a coating method can be used.

In one embodiment, the manufacturing method of the present invention provides a method of manufacturing a release film for manufacturing a resin sheet and a multilayer ceramic capacitor.

(resin sheet)
The resin sheet in the present invention is not particularly limited as long as it is a sheet that is molded on the surface of the release layer opposite to the base material, and for example, a resin sheet molding composition containing a resin component and a crosslinking agent is cured. Examples include resin sheets formed from organic components having film-forming properties by melt film forming or solution film forming. In one embodiment, the release film of the present invention is a release film for producing a resin sheet containing an inorganic compound. Examples of the inorganic compound include metal particles, metal oxides, minerals, and the like, such as calcium carbonate, silica particles, aluminum particles, barium titanate particles, and the like. Since the present invention has a release layer with high smoothness, even if the resin sheet contains these inorganic compounds, there are disadvantages that may be caused by the inorganic compounds, such as breakage of the resin sheet, and separation of the resin sheet from the release layer. The problem of difficulty in peeling can be suppressed.
The resin component forming the resin sheet can be appropriately selected depending on the purpose. In one embodiment, the resin sheet containing an inorganic compound is a ceramic green sheet. For example, the ceramic green sheet can include barium titanate as an inorganic compound. Further, as a resin component, for example, a polyvinyl butyral resin can be included.

(Ceramic green sheet and ceramic capacitor)
Generally, a multilayer ceramic capacitor has a rectangular parallelepiped ceramic body. Inside the ceramic body, first internal electrodes and second internal electrodes are provided alternately along the thickness direction. The first internal electrode is exposed on the first end surface of the ceramic body. A first external electrode is provided on the first end surface. The first internal electrode is electrically connected to the first external electrode at the first end surface. The second internal electrode is exposed on the second end surface of the ceramic body. A second external electrode is provided on the second end surface. The second internal electrode is electrically connected to the second external electrode at the second end surface.

In one embodiment, the release film of the present invention is a release film for producing ceramic green sheets, and is used to produce such a multilayer ceramic capacitor.
For example, by using the release film for ceramic green sheet production of the present invention, a ceramic green sheet can be produced in the following manner. First, using the release film of the present invention as a carrier film, a ceramic slurry for forming a ceramic body is applied and dried. A conductive layer for forming the first or second internal electrode is printed on the coated and dried ceramic green sheet. A ceramic green sheet, a ceramic green sheet printed with a conductive layer for forming the first internal electrode, and a ceramic green sheet printed with a conductive layer for forming the second internal electrode are laminated as appropriate and pressed. By this, a mother laminate is obtained. The mother laminate is divided into multiple parts to produce raw ceramic bodies. A ceramic body is obtained by firing a raw ceramic body. Thereafter, the multilayer ceramic capacitor can be completed by forming the first and second external electrodes.

The present invention will be explained in more detail below using Examples, but the present invention is not limited to these Examples in any way. The characteristic values used in the present invention were evaluated using the following method.

(Release layer thickness)
After cutting the release film into triangular pieces, a 2 nm thick Pt (platinum) layer was formed on the surface of the release layer by coating. The obtained sample was fixed in a multiaxial embedding capsule, embedded using epoxy resin, and sliced in a direction perpendicular to the surface direction of the film using a microtome ULTRACUT-S to obtain a 50 nm thick sample. An ultrathin sample was obtained. Next, the obtained ultra-thin sample was mounted on a grid and steam-stained with 2% osmic acid at 60° C. for 2 hours. Using an ultra-thin sample after steam staining, the cross section of the film was observed using a transmission electron microscope LEM-2000 at an accelerating voltage of 100 kV, and the thickness of the release layer was measured. Measurements were performed at arbitrary 10 points, and the average value thereof was taken as the thickness of the release layer.

(surface tension)
The surface tension of the aqueous coating composition was measured by the pendant drop method using a contact angle meter (manufactured by Kyowa Kaimen Kagaku Co., Ltd., fully automatic contact angle meter DM-701) under conditions of 23° C. and 50% RH. After forming the maximum amount of liquid that could be retained without falling, the surface tension was calculated using the ds/de method using the attached analysis software FAMAS. The measurement was performed five times in total, and the average value was used as the value.

(Liquid temperature of aqueous coating composition)
After preparing the aqueous coating composition and before applying it to the polyester film, the temperature of the solution was measured using a waterproof digital thermometer, and the value was used.

(Coating uniformity of release layer)
The release film obtained by winding it up into a roll was unwound and cut into an A4 size sheet, and the surface of the release layer was visually observed using a fluorescent lamp and a halogen light. The number of pieces per sample) was compared and evaluated based on the following criteria.
◎: No coating defects ○: 1 to 2 coating defects △: 3 to 5 coating defects ×: 6 or more coating defects

(Ceramic sheet removability)
A slurry composition I consisting of the following materials was stirred and mixed for 10 minutes, and dispersed for 10 minutes with zirconia beads having a diameter of 0.5 mm using a bead mill to obtain a primary dispersion. Thereafter, slurry composition II consisting of the following materials was added to the primary dispersion at a ratio of (slurry composition I): (slurry composition II) = 3.4:1.0, and the diameter was 0. Secondary dispersion was performed using .5 mm zirconia beads for 10 minutes to obtain a ceramic slurry.
(Slurry composition I)
Toluene 22.3 parts by mass Ethanol 18.3 parts by mass Barium titanate (average particle size 100 nm) 57.5 parts by mass Homogenol L-18 (manufactured by Kao Corporation) 1.9 parts by mass (Slurry Composition II)
Toluene 39.6 parts by mass Ethanol 39.6 parts by mass Dioctyl phthalate 3.3 parts by mass Polyvinyl butyral (Sekisui Chemical Co., Ltd. S-LEC BM-S) 16.3 parts by mass
1-Ethyl-3-methylimidazolium ethyl sulfate 0.5 parts by mass Next, the mold release surface of the obtained mold release film sample was coated with an applicator so that the dried slurry had a thickness of 2.0 μm and heated at 60°C. The film was dried for 1 minute to obtain a release film with a ceramic green sheet. The obtained mold release film with ceramic green sheet was neutralized using a static eliminator (manufactured by Keyence Corporation, SJ-F020), and then tested using a peel tester (manufactured by Kyowa Interface Science Co., Ltd., VPA-3, load cell load 0.1N). The film was peeled off at a peeling angle of 90 degrees, a peeling temperature of 25° C., and a peeling speed of 0.3 m/min. For the direction of peeling, stick a double-sided adhesive tape (manufactured by Nitto Denko Corporation, No. 535A) on the SUS plate attached to the peel tester, and then apply a release film on top of it by adhering the ceramic green sheet side to the double-sided tape. was fixed and peeled off by pulling the release film side. Among the measured values obtained, the average value of the peeling force over a peeling distance of 20 mm to 70 mm was calculated, and this value was taken as the peeling force. The measurement was carried out five times in total, and the average value of the peeling force was used for evaluation. Judgment was made based on the obtained peel force values based on the following criteria.
〇: Less than 2.0 mN/mm △: Less than 5.0 mN/mm ×: 5.0 mN/mm or more

(Appearance of slurry application)
A ceramic green sheet with a thickness of 1 μm was molded on the mold release surface of the mold release film in the same manner as in the evaluation of the releasability of the ceramic slurry. The end face of the ceramic green sheet molded on the release film was observed using an optical microscope from the side on which the ceramic green sheets were laminated, and visually judged according to the following criteria.
○: Ceramic green sheet end surface is uniform ×: Ceramic green sheet end surface is uneven

(Sliding angle)
Measurements were made using a contact angle meter (manufactured by Kyowa Kaimen Kagaku Co., Ltd., fully automatic contact angle meter DM-701) in an environment of 23°C and 50% humidity. Specifically, the release film was placed on a flat glass substrate, and 7.0 μL of water was dropped onto the surface of the release layer. Three seconds after dropping, the glass plate was tilted from 0° to 90° at a tilting speed of 1.0°/sec, the movement determination distance was 100 dots, and the tilt angle at which the droplet began to move was taken as the measured value of the sliding angle. The measurement was performed five times in total, and the average value was used as the sliding angle.

(adhesion energy)
Using the analysis software FAMAS included with the fully automatic contact angle meter DM-701, the values calculated from the above-mentioned water sliding angle, liquid landing radius, liquid removal mass, and gravitational acceleration were adopted.

(Peeling force after toluene immersion treatment)
The release film to be measured was left to stand and immersed in toluene for 15 minutes, then taken out from the toluene, and air-dried for 3 hours to volatilize the toluene attached to the release film. Thereafter, an adhesive tape ("No. 31B Tape" manufactured by Nitto Denko Corporation) was attached to the surface of the release layer of the release film, and the release film with the adhesive tape was cut into strips with a width of 25 mm and a length of 150 mm. After the cut release film with adhesive tape was pressed with a 5 kg pressure roller, the release film with tape was sandwiched between 750 g glass plates and held in a 70°C environment for 20 hours. Thereafter, one end of the adhesive tape was fixed, one end of the release film was supported, and the release film side was pulled at a speed of 300 mm/min in an environment of 23°C, and measurements were taken using T-peel. The measurement was performed three times in total, and the average value was converted to a 50 mm width equivalent value and used as the value. For the measurement, a tensile tester ("AUTOGRAPHAG-X" manufactured by Shimadzu Corporation) was used.

<Manufacture example 1>
(Silicone emulsion A)
Using an emulsifying device (manufactured by NP Lab Co., Ltd., device name "Ultra Planetary Mixer") that can stir the entire inside of the container, a1 of formula (I) is 99 mol%, b1 is 1 mol%, 91% by mass of silicone oil with a number average molecular weight of 27,000, the number of alkyl group chains as a surfactant is 12, and the number of ethylene oxide chains is 9 (structure shown by n = 9, m = 12 in formula (IV)). A raw material consisting of 9.0% by mass of a certain polyoxyethylene alkyl ether (number average molecular weight 582, boiling point 283°C) was mechanically emulsified in an aqueous medium to obtain silicone emulsion A with a solid content of 40% by mass. Furthermore, the emulsion particle size was adjusted to an average particle size of 200 nm by adjusting the stirring speed and stirring time during emulsification.

H _2m+1 C _m -O-(CH ₂ -CH ₂ -O) _n -H (IV)

(Silicone emulsion B)
Using an emulsifying device (manufactured by NP Lab Co., Ltd., device name "Ultra Planetary Mixer") that can stir the entire inside of the container, a2 of formula (II) is 50 mol%, b2 is 50 mol%, 91% by mass of silicone oil with a number average molecular weight of 5500, the number of alkyl group chains as a surfactant is 12, and the number of ethylene oxide chains is 9 (structure shown by n = 9, m = 12 in formula (IV)). A raw material consisting of 9.0% by mass of polyoxyethylene alkyl ether (number average molecular weight: 582, boiling point: 283°C) was mechanically emulsified in an aqueous medium to obtain silicone emulsion B with a solid content of 40% by mass. Furthermore, the emulsion particle size was adjusted to an average particle size of 180 nm by adjusting the stirring speed and stirring time during emulsification.

An aqueous coating composition was obtained by mixing silicone emulsion A, silicone emulsion B, and water at the ratio shown in Table 1 so that the solid content concentration was 5.0% by mass. At this time, the amount of surfactant contained in the aqueous coating composition was 9.0% by mass when the total amount of silicone emulsion A and silicone emulsion B was taken as 100. In addition, based on the total weight of the aqueous coating composition, 0.02% by mass of a platinum catalyst (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: CAT-PM-10A) and 150ppm of a crosslinking reaction inhibitor (1-ethynylcyclohexanol) were added. They were mixed and used.

<Manufacture example 2>
(Silicone emulsion C)
Using an emulsifying device (manufactured by NP Lab Co., Ltd., device name "Ultra Planetary Mixer") that can stir the entire inside of the container, a1 of formula (I) is 99 mol%, b1 is 1 mol%, 95% by mass of silicone oil with a number average molecular weight of 27,000, the number of alkyl group chains as a surfactant is 12, and the number of ethylene oxide chains is 9 (structure shown by m = 12, n = 9 in formula (IV)). A raw material consisting of 5.0% by mass of a certain polyoxyethylene alkyl ether (number average molecular weight 582, boiling point 283°C) was mechanically emulsified in an aqueous medium to obtain silicone emulsion C with a solid content of 40% by mass. Furthermore, the emulsion particle size was adjusted to an average particle size of 200 nm by adjusting the stirring speed and stirring time during emulsification.

An aqueous coating composition was obtained by mixing silicone emulsion C, silicone emulsion B, and water at the ratio shown in Table 1 so that the solid content concentration was 5%. At this time, the amount of surfactant contained in the aqueous coating composition was 5.2% by mass when the total amount of silicone emulsion C and silicone emulsion B was taken as 100. In addition, based on the total weight of the aqueous coating composition, 0.02% by mass of a platinum catalyst (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: CAT-PM-10A) and 150ppm of a crosslinking reaction inhibitor (1-ethynylcyclohexanol) were added. They were mixed and used.

<Production Examples 3 to 5>
(Silicone emulsion D)
Using an emulsifying device that can stir the entire inside of the container (manufactured by NP Lab Co., Ltd., device name "Ultra Planetary Mixer"), 90% by mass of silicone having a Q unit represented by SiO _4/2 was mixed at the interface. As an activator, polyoxyethylene alkyl ether (number average molecular weight 582, boiling point 283 ° C. ) A raw material consisting of 10% by mass was mechanically emulsified in an aqueous medium to obtain silicone emulsion D with a solid content of 40% by mass. At this time, silicone having a Q unit represented by SiO _4/2 is shown by the formula (III), R1 is a vinyl group, R2 is a methyl group, and the Si atom to which the vinyl group is directly bonded has a vinyl group. Only one group is bonded, and the content of Si atoms bonded to the vinyl group is 5 mol% with respect to all Si atoms in the silicone with Q units expressed as SiO _4/2 , and the Q unit The content of Si atoms contained in was 40 mol%. Furthermore, the emulsion particle size was adjusted to an average particle size of 200 nm by adjusting the stirring speed and stirring time during emulsification.
R1 _a R2 _b SiO _(4-ab)/2 ...(III)
(In formula (I), R1 is an alkenyl group having 2 to 8 carbon atoms, R2 is a monovalent saturated hydrocarbon group having 1 to 16 carbon atoms selected from an alkyl group or an aryl group, and a is 0 to 3 , b is an integer between 0 and 3 and satisfies a+b≦3.)

An aqueous coating composition was obtained by mixing silicone emulsion A, silicone emulsion B, silicone emulsion D, and water at the ratio shown in Table 1 so that the solid content concentration was 5%. At this time, when the total amount of silicone emulsion A, silicone emulsion B, and silicone emulsion D is taken as 100, the amount of surfactant contained in the aqueous coating composition is 9.4% by mass in Production Example 3 and 9.2% by mass in Production Example 4. The mass % in Production Example 5 was 9.6 mass %. Furthermore, based on the total weight of the aqueous coating composition, 0.02% by mass of a platinum catalyst (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: CAT-PM-10A) and 150ppm of a crosslinking reaction inhibitor (1-ethynylcyclohexanol) were mixed. I used it.

<Manufacture example 6>
(Silicone emulsion E)
Using an emulsifying device (manufactured by NP Lab Co., Ltd., device name "Ultra Planetary Mixer") that can stir the entire inside of the container, a1 of formula (I) is 99 mol%, b1 is 1 mol%, 91% by mass of silicone oil with a number average molecular weight of 27,000, the number of alkyl group chains as a surfactant is 12, and the number of ethylene oxide chains is 6 (structure shown by m = 12, n = 6 in formula (IV)). A raw material consisting of 9.0% by mass of a certain polyoxyethylene alkyl ether (number average molecular weight 450, boiling point 230°C) was mechanically emulsified in an aqueous medium to obtain silicone emulsion E with a solid content of 40% by mass. Furthermore, the emulsion particle size was adjusted to an average particle size of 200 nm by adjusting the stirring speed and stirring time during emulsification.

(Silicone emulsion F)
As a surfactant, polyoxyethylene alkyl ether (number average molecular weight 450, boiling point 230 It was prepared in the same manner as silicone emulsion B, except that a raw material containing 9.0% by mass (°C) was used for emulsification.

(Silicone emulsion G)
As a surfactant, polyoxyethylene alkyl ether (number average molecular weight 450, boiling point 230 It was prepared in the same manner as Silicone Emulsion D, except that the emulsification was performed using a raw material containing 10% by mass (° C.).

An aqueous coating composition was obtained by mixing silicone emulsion E, silicone emulsion F, silicone emulsion G, and water at the ratio shown in Table 1 so that the solid content concentration was 5%. At this time, the amount of surfactant contained in the aqueous coating composition was 9.4% by mass when the total amount of silicone emulsion E, silicone emulsion F, and silicone emulsion G was taken as 100. Furthermore, based on the total weight of the aqueous coating composition, 0.02% by mass of a platinum catalyst (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: CAT-PM-10A) and 150ppm of a crosslinking reaction inhibitor (1-ethynylcyclohexanol) were mixed. I used it.

<Manufacture example 7>
Silicone emulsion A, silicone emulsion B, water, and isopropyl alcohol were mixed at the ratio shown in Table 1 so that the solid content concentration was 5.0% by mass to obtain an aqueous coating composition. At this time, isopropyl alcohol was used in an amount of 5% by mass based on the total amount of the aqueous coating composition. Further, the amount of surfactant contained in the aqueous coating composition was 9.0% by mass when the total amount of silicone emulsion A and silicone emulsion B was taken as 100. In addition, based on the total weight of the aqueous coating composition, 0.02% by mass of a platinum catalyst (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: CAT-PM-10A) and 150ppm of a crosslinking reaction inhibitor (1-ethynylcyclohexanol) were added. They were mixed and used.
<Production example 8>
(Silicone emulsion H)
Using an emulsifying device (manufactured by NP Lab Co., Ltd., device name "Ultra Planetary Mixer") that can stir the entire inside of the container, a1 of formula (I) is 99 mol%, b1 is 1 mol%, 98% by mass of silicone oil with a number average molecular weight of 27,000, the number of alkyl group chains as a surfactant is 12, and the number of ethylene oxide chains is 9 (structure shown by m = 12, n = 9 in formula (IV)). A raw material consisting of 0.1% by mass of a certain polyoxyethylene alkyl ether (number average molecular weight 582, boiling point 283°C) was mechanically emulsified in an aqueous medium to obtain silicone emulsion H with a solid content of 40% by mass. Furthermore, the emulsion particle size was adjusted to an average particle size of 200 nm by adjusting the stirring speed and stirring time during emulsification.

(Silicone emulsion I)
Using an emulsifying device (manufactured by NP Lab Co., Ltd., device name "Ultra Planetary Mixer") that can stir the entire inside of the container, a2 of formula (2) is 50 mol%, b2 is 50 mol%, 98% by mass of silicone oil with a number average molecular weight of 5500, a polyester having 12 alkyl group chains and 9 ethylene oxides (structure represented by m=12, n=9 in formula (IV)) as a surfactant. A raw material consisting of 0.1% by mass of oxyethylene alkyl ether (number average molecular weight 582, boiling point 283°C) was mechanically emulsified in an aqueous medium to obtain silicone emulsion I with a solid content of 40% by mass. Furthermore, the emulsion particle size was adjusted to an average particle size of 180 nm by adjusting the stirring speed and stirring time during emulsification.

An aqueous coating composition was obtained by mixing silicone emulsion H, silicone emulsion I, and water at the ratio shown in Table 1 so that the solid content concentration was 5%. At this time, the amount of surfactant contained in the aqueous coating composition was 0.1% by mass when the total amount of silicone emulsion H and silicone emulsion I was taken as 100. Furthermore, based on the total weight of the aqueous coating composition, 0.02% by mass of a platinum catalyst (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: CAT-PM-10A) and 150ppm of a crosslinking reaction inhibitor (1-ethynylcyclohexanol) were mixed. I used it.

<Production example 9>
(Silicone Emulsion J)
Using an emulsifying device (manufactured by NP Lab Co., Ltd., device name "Ultra Planetary Mixer") that can stir the entire inside of the container, a1 of formula (I) is 99 mol%, b1 is 1 mol%, 91% by mass of silicone oil with a number average molecular weight of 27,000, the number of alkyl group chains as a surfactant is 12, and the number of ethylene oxide chains is 4 (structure shown by m = 12, n = 4 in formula (IV)). A raw material consisting of 9.0% by mass of a certain polyoxyethylene alkyl ether (number average molecular weight 362, boiling point 182°C) was mechanically emulsified in an aqueous medium to obtain silicone emulsion J with a solid content of 40% by mass. Furthermore, the emulsion particle size was adjusted to an average particle size of 200 nm by adjusting the stirring speed and stirring time during emulsification.

(Silicone emulsion K)
Using an emulsifying device (manufactured by NP Lab Co., Ltd., device name "Ultra Planetary Mixer") that can stir the entire inside of the container, a2 of formula (2) is 50 mol%, b2 is 50 mol%, 91% by mass of silicone oil with a number average molecular weight of 5500, the number of alkyl group chains as a surfactant is 12, and the number of ethylene oxide chains is 4 (structure shown by m = 12, n = 4 in formula (IV)) A raw material consisting of 9.0% by mass of polyoxyethylene alkyl ether (number average molecular weight: 362, boiling point: 182°C) was mechanically emulsified in an aqueous medium to obtain silicone emulsion K with a solid content of 40% by mass. Furthermore, the emulsion particle size was adjusted to an average particle size of 180 nm by adjusting the stirring speed and stirring time during emulsification.

An aqueous coating composition was obtained by mixing silicone emulsion J, silicone emulsion K, and water at the ratio shown in Table 1 so that the solid content concentration was 5%. At this time, the amount of surfactant contained in the aqueous coating composition was 9.0% by mass when the total amount of silicone emulsion J and silicone emulsion K was taken as 100. Furthermore, based on the total weight of the aqueous coating composition, 0.02% by mass of a platinum catalyst (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: CAT-PM-10A) and 150ppm of a crosslinking reaction inhibitor (1-ethynylcyclohexanol) were mixed. I used it.

<Production example 10>
(Silicone emulsion L)
Using an emulsifying device that can stir the entire inside of the container (manufactured by NP Lab Co., Ltd., device name "Ultra Planetary Mixer"), 90% by mass of silicone having a Q unit represented by SiO _4/2 was mixed at the interface. As an activator, polyoxyethylene alkyl ether (number average molecular weight 362, boiling point 182°C) has 12 alkyl group chains and 4 ethylene oxides (structure represented by m=12, n=4 in formula (IV)). A silicone emulsion L having a solid content of 40% by mass was obtained by mechanically emulsifying the raw material consisting of 10% by mass in an aqueous medium. At this time, silicone having a Q unit represented by SiO _4/2 is shown by the formula (III), R1 is a vinyl group, R2 is a methyl group, and the Si atom to which the vinyl group is directly bonded has a vinyl group. Only one group is bonded, and the content of Si atoms bonded to the vinyl group is 5 mol% with respect to all Si atoms in the silicone with Q units expressed as SiO _4/2 , and the Q unit The content of Si atoms contained in was 40 mol%. Furthermore, the emulsion particle size was adjusted to an average particle size of 200 nm by adjusting the stirring speed and stirring time during emulsification.

An aqueous coating composition was obtained by mixing silicone emulsion J, silicone emulsion K, silicone emulsion L, and water at the ratio shown in Table 1 so that the solid content concentration was 5%. At this time, the amount of surfactant contained in the aqueous coating composition was 9.4% by mass when the total amount of silicone emulsion J, silicone emulsion K, and silicone emulsion L was taken as 100. Furthermore, based on the total weight of the aqueous coating composition, 0.02% by mass of a platinum catalyst (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: CAT-PM-10A) and 150ppm of a crosslinking reaction inhibitor (1-ethynylcyclohexanol) were mixed. I used it.

<Example 1>
Polyethylene terephthalate ([η] = 0.63 dl/g, Tg = 78°C) containing 0.25% by mass of calcium carbonate particles with an average particle diameter of 0.6 μm was melted in an extruder to create a filter with a filtration accuracy of 10 μm. The film was extruded through a die and cooled using a cooling drum in a conventional manner to obtain an unstretched film. After stretching the polyester film 3.2 times in the longitudinal direction at 80° C., the aqueous coating composition obtained in Production Example 1 was uniformly applied to one surface of the polyester film using a roll coater. Next, this coated film was dried at 115°C, stretched 4.0 times in the transverse direction at 145°C, further heat-set at 230°C for about 10 seconds, and then wound into a roll to obtain the separation shown in Table 1. A roll of a release film (thickness: 25 μm) having a mold layer was obtained. The release film was unwound from the obtained release film roll and the samples were cut into A4 size sheets, and the evaluations shown in Table 1 were performed. The aqueous coating composition was applied in an amount such that the thickness of the release layer after stretching was as shown in Table 1. Details of the aqueous coating composition are shown in Table 1A, and various physical properties of the film are shown in Table 1B.

<Example 2 and 3>
A release film was obtained in the same manner as in Example 1, except that the heat setting temperature was changed to the conditions listed in Table 1B.

<Examples 4 to 8>
A release film was obtained in the same manner as in Example 1, except that the aqueous coating compositions listed in Tables 1A and 1B were used.

<Example 9>
A release film was obtained in the same manner as in Example 8, except that the heat setting temperature was changed to the one shown in Table 1B.

<Example 10>
A release film was obtained in the same manner as in Example 1, except that the aqueous coating composition shown in Table 1A was used.

<Comparative example 1>
On one surface of a 25 μm thick biaxially stretched polyester film (manufactured by Toyobo Co., Ltd., Toyobo Ester Film E5100), apply a coating solution with the following composition using reverse gravure so that the release layer thickness after drying becomes 0.02 μm. It was coated using an offline coating method and dried at 140°C for 15 seconds. After drying, ultraviolet rays were irradiated on the cooling roll using an ultraviolet irradiator (manufactured by Heraeus, H bulb) at a cumulative light intensity of 100 mJ/cm ² , and the film was wound into a roll to obtain a release film roll. The release film was unwound from the obtained release film roll, and samples cut into A4 size sheets were used for evaluation as shown in Table 1B.
Methyl ethyl ketone 49.49 parts by mass Toluene 49.48 parts by mass LTC-851 (manufactured by Shin-Etsu Chemical Co., Ltd., silicone release agent) 1.00 parts by mass CAT-PL-50T (manufactured by Shin-Etsu Chemical Co., Ltd., platinum catalyst) 0.03 parts by mass Department

<Comparative example 2>
A release film was obtained in the same manner as in Example 1, except that the aqueous coating composition shown in Table 1A was used.

As shown in Table 1, in Examples 1 to 10, release films with high adhesion energy calculated from the sliding angle, excellent wettability of slurry, and excellent releasability of ceramic sheets were obtained. On the other hand, in Comparative Example 1, the release layer was formed using an offline coating method using an aqueous coating composition that did not contain a surfactant, so the adhesion energy calculated from water sliding was low and the wettability deteriorated. . In Comparative Example 2, since the surface tension of the aqueous coating composition was high, the coating uniformity of the aqueous coating composition was poor, and repellency occurred. Therefore, the appearance of the applied slurry was poor. In addition, the peeling force after toluene immersion treatment greatly exceeded 2000 mN/50 mm, and the peelability was also poor.

<Reference examples 1 and 2>
A release film was obtained in the same manner as in Example 1, except that the aqueous coating composition shown in Table 2A and the conditions shown in Table 2B were used. Various physical properties are shown in Table 2B.

<Reference example 3>
The aqueous coating composition prepared in Production Example 1 was applied onto one surface of a 25 μm thick biaxially stretched polyester film (Toyobo Ester Film E5100, manufactured by Toyobo Co., Ltd.) so that the release layer thickness after drying would be 0.15 μm. It was coated using an offline coating method and dried at 140°C for 15 seconds. After drying, a release film was obtained by winding it up into a roll.

<Reference example 4>
Using the aqueous coating composition prepared in Production Example 3, a release film was obtained in the same manner as in Example 1, except that the heat setting temperature was 160°C. The surface tension of the aqueous coating composition in the application process was 31 mJ/m ² .

<Reference example 5>
Using the aqueous coating composition prepared in Production Example 3, a release film was obtained in the same manner as in Example 1, except that the aqueous coating composition was heated to a liquid temperature of 50°C. The surface tension of the aqueous coating composition in the application process was 31 mJ/m ² .

As shown in Tables 2A and B, in Reference Examples 1 and 2, the number average molecular weight of the surfactant contained in the aqueous coating composition was low, and the boiling point was low. Therefore, the surfactant volatilized during the process of drying and curing the release layer, and the adhesion energy calculated from the sliding angle was low, resulting in deterioration of wettability.
In Reference Example 3, the aqueous coating composition prepared in Production Example 1 was applied by an offline coating method, so the curing temperature was low, and blocking occurred when the release layer was uncured and wound into a roll. Therefore, the appearance of the slurry coating was poor and the releasability was also poor. In Reference Example 4, the heat setting temperature was low and the curing of the release layer was insufficient, so blocking occurred when it was wound up into a roll, the appearance of the slurry coating was poor, and the releasability was also poor. In Reference Example 5, since the liquid temperature of the aqueous coating composition was high, breakage of the emulsion was observed, repelling occurred during application of the aqueous coating composition, and deterioration in coating uniformity was observed. As a result, the appearance of the slurry coating was poor and the releasability was also deteriorated.
Details of the aqueous coating composition are shown in Table 1A, and various physical properties regarding the film are shown in Table 1B. Further, reference examples are shown in Table 2A and Table 2B.

Since the release film of the present invention has high releasability and wettability of the release layer, it is possible to suppress the occurrence of defects when molding a thin resin sheet, especially a ceramic green sheet.

Claims

A release film having a polyester film and a release layer in this order,
The release layer is a layer formed by reacting and solidifying an aqueous coating composition,
The aqueous coating composition contains an organic solvent in an amount of 10 parts by mass or less based on 100 parts by mass of the total amount of the aqueous coating composition,
The aqueous coating composition comprises:
(a) a first silicone emulsion containing at least two or more alkenyl groups in one molecule;
(b) a second silicone emulsion containing at least two or more hydrogen groups in one molecule, and
(d) In the release layer containing a surfactant,
The adhesion energy of the surface of the release layer calculated from the sliding angle of water is 6.0 mJ/m 2 or more,
A release film with a tape peeling force of 2000mN/50mm or less measured by the following method;
After the release film was immersed in toluene for 15 minutes and air-dried, an adhesive tape was laminated on the release layer and the release film with the tape was pressed under a load of 5 kg. After holding the release film with the tape at 70°C for 20 hours, The tape peeling force is measured by T-shaped peeling at a peeling speed of 0.3 m/min.
The aqueous coating composition is
(c) The release film according to claim 1, comprising an aqueous dispersion containing silicone having a Q unit represented by SiO 4/2 .
In the aqueous coating composition,
(a) the first silicone emulsion containing at least two or more alkenyl groups in one molecule has a number average molecular weight of 1,000 or more and less than 30,000;
(b) The release film according to claim 1, wherein the second silicone emulsion containing at least two or more hydrogen groups in one molecule has a number average molecular weight of 1,000 to 10,000.
The release film is obtained by applying the aqueous coating composition to the base film before the crystal orientation is completed, stretching in at least one direction, and then heat-treating the base film to complete the crystal orientation of the base film. The release film according to claim 1, wherein the release film is formed.
2. The release film according to claim 1, wherein the polyester film has a surface layer substantially free of inorganic particles, and the release layer is formed on the surface layer.
The mold release film according to claim 1, wherein the mold release film is a mold release film for manufacturing a multilayer ceramic capacitor or a resin sheet.
A method for producing a release film, comprising the following steps;
A coating step of applying an aqueous coating composition to at least one side of a polyester film, the coating step comprising:
The aqueous coating composition contains an organic solvent in an amount of 10 parts by mass or less based on 100 parts by mass of the total amount of the aqueous coating composition,
Contains water, a water-soluble component and/or a water-dispersed emulsion,
a coating step in which the surface tension of the aqueous coating composition is 40 mN/m or less; and
a heating step of heating the polyester film coated with the aqueous coating composition;
The aqueous coating composition comprises:
(A) a first silicone emulsion containing at least two or more alkenyl groups in one molecule;
(B) a second silicone emulsion containing at least two or more hydrogen groups in one molecule, and
(D) Contains a surfactant;
the coating step using the aqueous coating composition in which the surfactant has a boiling point of 200° C. or higher;
The method for producing a release film according to claim 7.
The method for producing a release film according to claim 7, wherein the heating step includes the following steps, and the heating step is performed after the coating step;
a drying step of drying the aqueous coating composition applied to one side of the polyester film;
a stretching step of stretching in a direction perpendicular to the longitudinal direction of the polyester film; and
A heat setting step of heat-treating the polyester film to complete crystal orientation.
In the coating step, the liquid temperature of the aqueous coating composition is 0°C or more and 40°C or less,
The method for producing a release film according to claim 7, wherein the maximum temperature in the heating step is 180°C or more and 250°C or less.
The method for producing a release film according to claim 7, for producing a release film for producing a resin sheet or a laminated ceramic capacitor.