JP2022122824A - Laminated polyester film and method for manufacturing polyester film - Google Patents

Abstract

To provide a laminated polyester film in which the removability of layers other than polyester film is excellent.SOLUTION: Provided is a laminated polyester film, which is a laminated polyester film having a polyester film and a hydrophilic layer X, and in which the thickness xa (nm) of the layer X and the roughness RzjisB (nm) of the surface on the side of the surface (B surface) which is a side opposite to the surface (A surface) on the side having the layer X of the polyester film satisfy the following condition 1. Condition 1: 1.5≤RzjisB/xa≤10.0.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a laminated polyester film excellent in removing a layer provided on the laminated polyester film.

While plastics are used in various fields, they are considered to be a cause of marine pollution such as microplastics, and there is an urgent need to reduce the environmental burden caused by plastics. In recent years, due to the evolution of the Internet of Things (IoT), the number of electronic devices such as CPUs installed in computers and smartphones has increased rapidly. number is also increasing exponentially. A general method for producing an MLCC is to use a plastic film as a substrate, laminate a ceramic green sheet and an electrode on a release film having a release layer provided on the substrate, dry and solidify, and then The laminate is peeled off from the release film, a plurality of layers are laminated, and the laminate is fired. In this process, the release film is discarded as an unnecessary material during the process.

That is, the explosive increase in the number of MLCCs in recent years has led to an increase in the amount of release films that are discarded as unnecessary materials, and this has become a problem for the environment. The components of the release layer contained in the release film used in the manufacturing process of MLCC are generally different in composition from the components constituting the film from the viewpoint of releasability, so the release layer is attached. If the release film is remelted as it is, the components of the release layer are present as foreign matter, making reuse difficult.

In addition, in the social change of "with corona", the demand for tablets, notebook PCs, displays, etc. is increasing due to the increase in remote work, etc., and the demand for polarizing film, which is a component of LCD monitors, is also growing. A laminate of polyvinyl alcohol resin and triacetyl cellulose resin is generally used as the polarizing film. Such a laminate is generally laminated with a protective film in order to reduce damage to the laminate during the manufacturing process of the liquid crystal monitor.

The manufacturing method of this protective film generally has a step of using a release film for process as a step of forming a pressure-sensitive adhesive for bonding with a polarizing film on one side of the protective film. That is, in the process of applying an adhesive to the release surface of the release film for the process, bonding it to one side of the protective film, and transferring the adhesive to one side of the protective film by peeling the release film for the process. be. The process release film used in the pressure-sensitive adhesive forming process is similar to the release film used in the MLCC manufacturing process. In that case, the components of the release layer are present as foreign matter, and may not be reused.

Patent Document 1 discloses a method of cleaning a release film having a release layer with a metal brush and reusing the film from which the release layer has been removed. Patent Literature 2 discloses a method in which a water-soluble resin layer is provided between a release layer and a polyester film, and the release layer is removed by washing with water and then reused.

JP 2012-171276 A Japanese Patent No. 4284936

However, when the release film is cleaned with a metal brush, there are problems that uniform cleaning cannot be performed and the removability of the release layer is not sufficient. In addition, the method of providing a layer of a water-soluble resin between the release layer and the polyester film has a problem that the release layer is not sufficiently removable after long-term storage, particularly in a moist and hot atmosphere. In view of the above, an object of the present invention is to provide a laminated polyester film excellent in removability of layers other than the polyester film.

In order to solve the above problems, a preferred embodiment of the present invention has the following configuration.
[I] A laminated polyester film having a polyester film and a hydrophilic layer X, wherein the thickness xa (nm) of the layer X and the surface (A surface) of the polyester film on the side having the layer X A laminated polyester film whose surface roughness RzjisB (nm) on the opposite side (side B) satisfies Condition 1 below.
Condition 1: 1.5≤RzjisB/xa≤10.0
[II] The laminated polyester film according to [I], wherein the thickness xa (nm) of the layer X and the surface roughness RzjisX (nm) of the layer X satisfy Condition 2 below.
Condition 2: 0.01≤RzjisX/xa≤3.0
[III] The laminated polyester film according to [I] or [II], wherein the thickness xa of the layer X is 10 nm or more and 500 nm or less.
[IV] The laminated polyester film according to any one of [I] to [III], wherein the surface free energy of the layer X satisfies the following conditions.
Condition 3: 20≦γX _P ≦30
Condition 4: _{6.0≤γXH≤10}
γX _P (mN/m): Polar component of surface free energy of layer X γX _H (mN/m): Hydrogen bond component of surface free energy of layer X [V] Layer Y satisfying the following conditions, the layer X, The laminated polyester film according to any one of [I] to [IV], which has polyester films in this order.
Condition 3: 80≤HY(1)≤120
Condition 4: 5≤|HY(1)-HY(20)|≤90
HY (1) (°): contact angle 1 second after water contacts layer Y HY (20) (°): contact angle 20 seconds after water contacts layer Y [VI] [V ] The laminated polyester film described in .
[VII] The laminated polyester film according to [VI], which is used for applications in which the layer X and the layer Y are removed after the release layer is peeled from the layer Y.
[VIII] The laminated polyester film according to [VII], which is used for reuse of the laminated polyester film from which the layers X and Y have been removed.
[IX] The laminated polyester film according to any one of [VI] to [VIII], wherein the release layer is a ceramic green sheet containing barium titanate as a main component.
[X] The laminated polyester film according to any one of [I] to [VIII], which is used as a release film for manufacturing a laminated ceramic capacitor (MLCC).
[XI] The laminated polyester film according to any one of [VI] to [VIII], wherein the release layer is an adhesive containing an acrylic resin as a main component.
[XII] The laminated polyester film according to any one of [I] to [VIII] and [XI], which is used as a release film for a polarizing plate manufacturing process.
[XIII] The polyester film has a laminated structure of three or more layers, which includes a layer (A layer) constituting side A, a layer (B layer) constituting side B, and an intermediate layer (C layer). The laminated polyester film according to any one of [I] to [XII], wherein any one or all of the A layer, the B layer, and the C layer contain a recycled polyester raw material.
[XIV] The polyester film has a laminate structure of three or more layers, which includes a layer (A layer) constituting side A, a layer (B layer) constituting side B, and an intermediate layer (C layer). The laminated polyester film according to any one of [I] to [XIII], wherein the layer C contains a recycled polyester raw material.
[XV] Using the laminated polyester film according to any one of [I] to [XIV], which has at least a release layer, a layer Y, and a polyester film in this order, the release layer is peeled off from the layer Y. a step of removing the layer Y from the film from which the release layer has been peeled; and a step of producing a recycled raw material from the film from which the release layer and the layer Y have been removed, and further using the recycled raw material to produce a film. A method for producing a polyester film, comprising a step of forming a film.
[XVI] A laminated polyester film comprising a polyester film and a layer Y, wherein the water contact angles HY(1) (°) and HY(20) (°) of the layer Y satisfy the following equations.
80≤HY(1)≤120, 5≤|HY(1)-HY(20)|≤90
HY (1) (°): contact angle 1 second after water contacts layer Y HY (20) (°): contact angle 20 seconds after water contacts layer Y

ADVANTAGE OF THE INVENTION According to this invention, the laminated polyester film excellent in the removability of layers other than a polyester film can be provided.

The present invention will be described in detail below with reference to specific examples.

The present invention relates to polyester films and laminated polyester films having one or more additional layers. The polyester referred to in the present invention comprises a dicarboxylic acid component and a diol component. In the present specification, the term "constituent" refers to a minimum unit that can be obtained by hydrolyzing a polyester. Dicarboxylic acid constituents constituting such polyesters include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 1,8-naphthalene. Dicarboxylic acids, aromatic dicarboxylic acids such as 4,4′-diphenyldicarboxylic acid and 4,4′-diphenyletherdicarboxylic acid, and ester derivatives thereof can be mentioned.

Diol constituents constituting such polyesters include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,2-butanediol, and 1,3-butanediol. and alicyclic diols such as cyclohexanedimethanol and spiroglycol, and diols in which a plurality of the above diols are linked. Among them, from the viewpoint of mechanical properties and transparency, polyethylene terephthalate (PET), polyethylene-2,6-naphthalene dicarboxylate (PEN), and isophthalic acid and naphthalene dicarboxylic acid are copolymerized with some of the dicarboxylic acid components of PET. However, polyester obtained by copolymerizing cyclohexanedimethanol, spiroglycol, and diethylene glycol as part of the diol component of PET is preferably used.

A preferred embodiment of the laminated polyester film of the present invention is a laminated polyester film having a polyester film and a hydrophilic layer X, wherein the thickness xa (nm) of the layer X and the layer X of the polyester film. The surface roughness RzjisB (nm) of the surface (B surface) opposite to the surface (A surface) is a laminated polyester film that satisfies the following condition 1, and from the viewpoint of simpler configuration and higher productivity A more preferable aspect is an aspect having the layer X on one side of the polyester film, and a more preferable aspect from the same viewpoint is an aspect having the layer X on one side of the polyester film. In addition, from the viewpoint of simpler configuration and higher productivity, in a preferred embodiment, the opposite surface (B surface) is opposite to the surface (A surface) having the layer X of the polyester film. It is an aspect which is a side surface (B surface).
Condition 1: 1.5≤RzjisB/xa≤10.0
The term "hydrophilicity" as used herein means that the surface free energy value is 10 mN/m or more when the surface free energy is measured by the method described in Examples. If the layer X is not exposed, the layer X is exposed by polishing until the thickness of the layer X is in the range of 30 to 70% of the original thickness of the layer X, and the surface free energy of the layer X is increased. shall be requested.

Examples of hydrophilic substances having a surface free energy value of 10 mN/m or more include water-soluble polyester-based resins, polyvinyl alcohol-based resins (hereinafter sometimes referred to as polyvinyl alcohol (PVA)), and polyvinylpyrrolidone-based resins. Resins (hereinafter sometimes referred to as polyvinylpyrrolidone (PVP)) and those containing starch as a main component can be exemplified. From the viewpoint of affinity with polyester film, water solubility, heat resistance, and durability against organic solvents (hereinafter sometimes referred to as solvent resistance), layer X is a polyvinyl alcohol-based polyvinyl alcohol-based polymer having polyvinyl alcohol as a main skeleton. It is preferred to have a resin. In particular, PVA is preferable because it has a small number of nonpolar sites and many hydrophilic groups, and thus has high hydrophilicity and solvent resistance. In addition, from the above-described viewpoint, the layer X preferably contains 60% by mass or more of the polyvinyl alcohol resin with respect to the entire layer X, more preferably 90% by mass or more, and further preferably 95% by mass or more. Polyvinyl alcohol It is particularly preferable to consist only of a polyvinyl alcohol-based resin. The term "water-soluble" as used herein means that the amount of change in mass when immersed in water at 50°C for 10 minutes is 15% or more, and an aqueous solution is formed. A specific method is as follows. That is, water-soluble means that the resin is immersed in water at 50 ° C. for 10 minutes, removed from the water, and the water droplets adhering to the surface are sufficiently wiped off with a waste cloth. The amount of change ΔM is 15% or more, and an aqueous solution is obtained.
ΔM=|(M2−M1)|/M1×100(%)
M1 (g): Resin mass before immersion in water at 50°C for 10 minutes M2 (g): Resin mass after immersion in water at 50°C for 10 minutes.

In addition, the main component means that 60% by mass or more of the component is contained in 100% by mass of the layer.

When a polyvinyl alcohol resin is used as the layer X, the degree of polymerization is preferably 300 to 1000, more preferably 300 to 800, even more preferably 400 to 600. When a polyvinyl alcohol-based resin having a degree of polymerization within the range described above is used, the coatability is improved when the layer X is provided by coating, and it is possible to prevent lamination from being performed or uneven distribution on the film due to poor coatability. can. The degree of polymerization refers to the average degree of polymerization determined according to JIS K 6726 (1994).

It is also a preferred embodiment to use copolymerized polyvinyl alcohol obtained by copolymerizing a functional group other than a hydroxyl group or an acetic acid group as a side chain of the polyvinyl alcohol resin used as the layer X. In particular, by introducing a hydrophilic functional group such as a 1,2-ethanediol group, a carboxyl group, a sulfonic acid group or a sodium base thereof, the hydrophilicity is improved and the water solubility is improved. The copolymerization amount is preferably 0.5 mol % or more and 20 mol % or less, more preferably 1 mol % or more and 10 mol % or less, based on the entire polyvinyl alcohol resin. When the amount of copolymerization is within the above range, the coatability is improved when the layer X is provided by coating, and it is possible to prevent lamination failure and uneven distribution of the resin component on the film.

When a polyvinyl alcohol-based resin is used as the layer X, it is preferable not to add an acrylic resin or a polyester resin as a binder to the layer X, or a cross-linking resin such as melamine or oxazoline for improving the film-forming properties. Binders and cross-linking resins interact with the side chain hydroxyl groups of the polyvinyl alcohol resin, making it impossible to control the degree of crystallinity and contact angle, which tends to result in undesirable values.

After the film is manufactured, the polyester film is wound up in a roll shape and transported to the place where it will be used as needed. However, it may be necessary to store the polyester film in roll form for a long period of time.

A film having a hydrophilic layer may change its properties when stored in a moist and heat atmosphere, especially when the film is wound in a roll shape and subjected to surface pressure. You may encounter problems when using it. Although the laminated polyester film of the present invention has a hydrophilic layer, by making the film satisfying condition 1, the occurrence of such a change in properties can be greatly suppressed. This will be explained in detail below.

When the laminated polyester film of the present invention is wound in a roll shape, the hydrophilic layer X is in contact with the surface (B surface) opposite to the surface (A surface) having the layer X of the polyester film. . RzjisB is the 10-point average roughness measured by the method described in Examples, and the larger the value, the greater the unevenness of the surface. When the value of RzjisB/xa is small and less than 1.5, that is, when RzjisB is small, or the value of xa is large, or both, under conditions where surface pressure is applied in the roll shape, in a moist and hot atmosphere The layer X tends to adhere to the surface of the B side, and the layer X may be transferred to the surface of the B side. In addition, the shape of the layer X may change, the washability of the layer X may deteriorate, or when another layer is applied in contact with the layer X, the coatability and function of the layer may deteriorate. .

When the value of RzjisB/xa is large and exceeds 10.0, that is, when RzjisB is large, or the value of xa is small, or both, under conditions where surface pressure is applied in the roll shape, B The shape of the layer X may change due to the unevenness of the face side surface itself, and the washability of the layer X may deteriorate. may decrease. From this point of view, the value of RzjisB/xa is more preferably 2.1 or more and 8.5 or less, and still more preferably 3.0 or more and 8.5 or less.

In the laminated polyester film of the present invention, the thickness xa (nm) of the layer X and the surface roughness RzjisX (nm) of the layer X preferably satisfy Condition 2 below.
Condition 2: 0.01≤RzjisX/xa≤3.0
RzjisX refers to surface roughness RzjisX of layer X, which is a 10-point average roughness measured by the method described in Examples. In the case of a two-layer structure of the layer X and the polyester film, RzjisX represents the roughness of the surface of the layer X opposite to the surface in contact with the polyester film. The roughness of the layer X is affected by the roughness of the A side of the polyester film, but by setting RzjisX/xa to 3.0 or less, the layer X can cover the entire A side, The characteristics of the layer X, that is, the hydrophilicity of the layer X, and when another layer is applied in contact with the layer X, the coatability and functions of the layer can be fully exhibited. On the other hand, by setting RzjisX/xa to 0.01 or more, the handleability of the film can be improved. From the same viewpoint as above, RzjisX/xa is more preferably 0.5 or more and 1.5 or less.

In the laminated polyester film of the present invention, the thickness xa of the layer X is preferably 10 nm or more and 500 nm or less. Setting xa to 10 nm or more makes it easy to satisfy the conditions 1 and 2, thereby increasing the productivity. In addition, by setting xa to 500 nm or less, it is possible to improve coatability when the layer X is provided by coating.

Further, when the polar component and the hydrogen bond component of the surface free energy of the layer X obtained by the method described later are γX _P (mN/m) and γX _H (mN/m), respectively, the surface free energy of the layer X is It is preferable to satisfy the following conditions.
Condition 3: 20≦γX _P ≦30
Condition 4: _{6.0≤γXH≤10}
γX _P (mN/m): Polar component of surface free energy of layer X γX _H (mN/m): Hydrogen bond component of surface free energy of layer X.

By setting the polar component γX _P and the hydrogen bond component γX _H of the surface free energy within the above range, the internal interaction of the layer X itself and the interaction between the layer X and the laminated polyester film are strengthened, improving solvent resistance. In addition, since the layer X can increase hydrophilicity, the layer X can be easily removed from the laminated polyester film by washing with water or an aqueous solution. γX _P is more preferably 22 mN/m or more and 26 mN/m or less, and γX _H is more preferably 7 mN/m or more and 9 mN/m or less. Each component of the surface free energy of the layer X is determined by the method described in Examples. In addition, when the layer X is not exposed, the layer X is exposed by polishing until the thickness of the layer X is in the range of 30 to 70% of the original thickness of the layer X, and the surface of the layer X is free. shall seek energy.

When the layer X does not satisfy the above conditions 3 and 4, when another layer is laminated on the layer X by coating, or when another layer is laminated on it by coating, the layer X is solvent resistant As a result, lamination property may be inferior.

When a polyvinyl alcohol-based resin is used as the layer X, the polar component γX _P and the hydrogen bonding component γX _H are set within the above ranges, so that the side chain group is an ionic compound such as a carboxylate, a sulfonate, or a tertiary ammonium salt. Introducing a polar group is also a preferred embodiment. Among them, sulfonates can be preferably used from the viewpoint of water solubility and solvent resistance. That is, layer X preferably contains a resin having a sulfonate-modified polyvinyl alcohol skeleton. The copolymerization amount is 0.5 mol % or more and 10 mol % or less, more preferably 0.5 mol % or more and 5 mol % or less, and still more preferably 1 mol % or more and 2 mol % or less based on the entire resin having a polyvinyl alcohol skeleton.

As a preferred embodiment of the laminated polyester film of the present invention, a laminated polyester film having a polyester film and a layer Y, wherein the water contact angles HY (1) (°) and HY (20) (°) of the layer Y are as follows: A laminated polyester film that satisfies the formula can be mentioned. Among them, a layer Y satisfying the following formula, the layer X, and a laminated polyester film having a polyester film in this order can be mentioned as a more preferable embodiment. , a laminated polyester film having a layer Y that satisfies the following conditions can be cited as a further preferred embodiment.
Condition 3: 80≤HY(1)≤120
Condition 4: 5≤|HY(1)-HY(20)|≤90
HY (1) (°): contact angle 1 second after water contacts layer Y HY (20) (°): contact angle 20 seconds after water contacts layer Y.

By controlling the contact angle with water and having the layer Y with HY(1) in the above range, the surface free energy of the layer Y can be reduced. It becomes possible to use it as a film.

That is, by controlling the contact angle with water to satisfy 80 ≤ HY (1), the releasability can be sufficiently improved, and the laminated polyester film having the layer Y can be suitably used as a release film. can. Further, by setting HY(1)≦120, it becomes difficult to repel the coating agent for forming the release layer when the release layer is provided by coating, and coating defects such as pinholes occur in the release layer. can be prevented.

In addition, HY(20) changes compared to HY(1), and by setting |HY(1)-HY(20)| becomes possible. That is, by changing the physical properties through water, the adhesiveness between the layer Y and the laminated polyester film is changed, so that the layer Y can be easily removed from the laminated polyester film using water.

5≦|HY(1)−HY(20)| means that the layer Y is permeable to water. By setting 5≦|HY(1)−HY(20)|, a large amount of water permeates the polyester film side of the base material, so that the surface of the base material is easily peeled off from other layers, and the layer It becomes easy to remove Y from the laminated polyester film with water and to recycle it. On the other hand, when |HY(1)-HY(20)| Local deterioration of washability can be suppressed. From the same point of view, |HY(1)-HY(20)| From the above viewpoint, it is preferable that HY(1)-HY(20)≧0°.

The method for setting |HY(1)-HY(20)| Between the polyester film and the layer Y, the layer X described above is provided so as to be in contact with the polyester film and the layer Y (that is, in the laminated polyester film having a hydrophilic layer X on at least one side of the polyester film, the layer X A preferred embodiment is the method of preparing a laminated polyester film having a layer Y on the opposite side of the surface in contact with the polyester film. In the latter case, by setting the polar component γX _P and the hydrogen bonding component γX _H of the surface free energy of the layer X to the ranges described above, it becomes easier to laminate the layer Y on the layer X, and at the same time, the layer easily absorbs water. Since X is in contact with layer Y, water in contact with layer Y permeates layer Y and is absorbed by layer X, so that the contact angle of water on layer Y also changes, |HY(1)− HY(20)| can easily be set within a preferred range. It is also important to set xa, RzjisB, and RzjisX within the ranges described above so as not to impair the properties of layer X, especially the hydrophilicity after storage of the roll-shaped roll.

|HY(1)-HY(20)| Examples of highly water-repellent resins that can be used for the layer Y include silicone compounds having dimethylsiloxane as a main skeleton, compounds having long-chain alkyl groups, and compounds having fluorine. Among them, a silicone (organopolysiloxane) having a dimethylsiloxane skeleton having high water permeability is preferable, and a resin having a curable silicone skeleton is particularly preferably used. The resin having a curable silicone skeleton is an "addition reaction type" organohydrogenpolyloxane obtained by heating and curing an organohydrogenpolyloxane and an organopolysiloxane containing an alkenyl group in the presence of a platinum catalyst. and an organopolysiloxane containing a hydroxyl group at its end and a "condensation reaction type" obtained by heating and curing using an organic tin catalyst, an organopolysiloxane containing an acryloyl group or a methacryloyl group, or an organopolysiloxane containing an alkenyl group A "UV curing type" that cures by compounding a photopolymerization initiator into an organopolysiloxane containing a mercapto group and irradiating it with UV light, and a "cationic type" that cures by photo-ring-opening the epoxy group with an onium salt initiator. Polymerization type” and the like. Any of them may be used, but the addition reaction type and the UV curing type are preferable from the viewpoint of productivity and peel strength.

Specific examples of the resin having an addition reaction type silicone skeleton preferably include polydimethylsiloxane and hydrogen siloxane containing vinyl groups at the terminals, such as KS-847, KS-847T manufactured by Shin-Etsu Chemical Co., Ltd., KS-841, KS-774, KS-3703T, X-62-2825, SD7333 manufactured by Dow Toray Industries, Inc., SRX357, SRX345, LTC310, LTC303E, LTC300B, LTC350G, LTC750A, LTC851, LTC759, LTC755, LTC755, LTC766 , etc. ("LTC" is a registered trademark).

Specific examples of the resin having a condensation reaction type silicone skeleton and the catalyst are preferably those containing polydimethylsiloxane and hydrogensiloxane containing hydroxyl groups at the terminals and an organotin catalyst, such as SRX290 and SY manufactured by Dow Toray Industries, Inc. LOFF23 can be mentioned.

Specific examples of resins and catalysts having a UV-curable silicone skeleton include those containing organopolysiloxanes containing acryloyl or methacryloyl groups and photopolymerization initiators, polydimethylsiloxanes containing alkenyl groups, and polydimethylsiloxanes containing mercapto groups. Those containing dimethylsiloxane and a photopolymerization initiator are preferable, and FM-0711, FM-0721, FM-0725, FM-7711, FM-7721, FM-7725 manufactured by JNC Co., Ltd., BY24 manufactured by Dow Toray Industries, Inc. -510H and BY24-544.

Specific examples of the resin having a cationic polymerizable silicone skeleton and the catalyst preferably include a siloxane containing an epoxy group and an onium salt initiator, such as TPR6501, UV9300 and XS56 manufactured by Momentive Performance Materials Japan LLC. -A2775 and the like.

It is also a preferred embodiment to provide the film of the present invention with the layer Y directly on one side of the polyester film. As a resin that can be used for the layer Y of the laminated polyester film having this structure, silicone compounds having a dimethylsiloxane skeleton, compounds having a long-chain alkyl group, compounds having a polyolefin skeleton, and fluorine-containing compounds such as perfluoroalkyl groups are selected. One or more selected compounds can be mentioned preferably. Among them, compounds having a polyolefin skeleton can be preferably used. Compounds having a polyolefin as a main skeleton tend to have good compatibility with surfactants described later, so that |HY(1)-HY(20)| tends to fall within the above range. Examples of compounds having a polyolefin skeleton include polyethylene, polypropylene, polybutadiene, hydrogenated polybutadiene, polyisoprene, hydrogenated polyisoprene, polyisobutylene, and α-olefin polymers using one or two of them. The above copolymers can be mentioned. An α-olefin is an olefin having a double bond at one end of the molecular chain, and examples thereof include 1-octene.

When a compound having a polyolefin skeleton is used for the layer Y of the laminated polyester film having a structure of substrate/layer Y, the layer Y preferably contains a surfactant. By adopting the above-described mode, water permeating through the layer Y spreads easily over the surface of the substrate, and 5≤|HY(1)-HY(20)| is easily satisfied. The amount of surfactant added to 100 parts by mass of the compound having a polyolefin skeleton is preferably 0.5 parts by mass or more and 10 parts by mass or less, more preferably 2.5 parts by mass or more and 6 parts by mass or less. be. When the amount of the surfactant added is 0.5 parts by mass or more, the amount of the surfactant is sufficient to spread over the entire layer Y, and water can easily permeate the layer Y. If the added amount of the surfactant exceeds 10 parts by mass, the surfactant may collect on the surface of the layer Y and contaminate the release material.

Examples of surfactants that can be used in the layer Y of the laminated polyester film having a structure of substrate/layer Y include various nonionic surfactants such as polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, poly Polyoxyethylene alkyl ethers such as oxyethylene stearyl ether and polyoxyethylene oleyl ether; Polyoxyethylene alkylphenyl ethers such as polyoxyethylene octylphenyl ether and polyoxyethylene nonylphenyl ether; Polyoxyethylene monolaurate and polyoxyethylene Polyoxyethylene fatty acid esters such as monostearate and polyoxyethylene monooleate; Sorbitan fatty acid esters such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate and sorbitan monooleate; Polyoxyethylene sorbitan monolaurate , polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan triisostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, etc. polyoxyethylene sorbitan fatty acid ester; polyoxyethylene glyceryl ether fatty acid ester; polyoxyethylene-polyoxypropylene block copolymer; These nonionic surfactants can be used singly or in combination of two or more.

In the laminated polyester film of the present invention, the layer Y has a large contact angle with water and a small surface energy. It can be suitably used for releasing the mold layer. Furthermore, since the layer X and the layer Y of the laminated polyester film of the present invention can be removed with water, the polyester film can be taken out by removing the layer X and the layer Y after peeling off the release material. is possible. Furthermore, it is preferable to take out and reuse the polyester film after removing the layer X and the layer Y from the laminated polyester film of the present invention. As a method of recycling, there are a method of providing a layer X and a layer Y again on the polyester film taken out and using it as a release film, and a method of remelting the polyester film and molding it again into a polyester film. A method of remelting and molding again into a polyester film is preferred, for which the application is not limited. From the viewpoint of taking out a polyester film with high purity, it is a more preferable aspect that the layer X and the polyester film are in contact with each other.

When a silicone compound, especially a compound containing a dimethylsiloxane bond, is used as the layer Y of the laminated polyester film of the present invention, the component containing the dimethylsiloxane bond is likely to become a foreign matter when mixed with the polyester film and remelted, and the polyester deteriorates. It is preferred to remove layer Y in order to re-melt and reuse the film of the present invention, as it may promote the process and may not be extrudable after melting.

When the laminated polyester film of the present invention having layer X and layer Y is used as a release film, the material to be released is an organic pressure-sensitive adhesive containing acrylic as a main component, or an inorganic material containing metal or metal oxide as a main component. sheet. The organic pressure-sensitive adhesive is used for producing polarizing films, and barium titanate, which is a metal oxide, is used for producing MLCCs. Under the circumstances where the amount of release film used in the process for manufacturing polarizing films and MLCCs is increasing, in the process of manufacturing polarizing films and MLCCs, the film of the present invention having layer X and layer Y can be used. After use in the manufacturing process, layers X and Y can be removed from the laminated polyester film of the present invention and the polyester film can be reused, thereby contributing to reduction of environmental load.

A method for producing the laminated polyester film of the present invention will be described below, but the present invention is not limited to the laminated polyester film obtained by this method.

For the polyester film used in the present invention, a method (melt casting method) of heating and melting a dried raw material in an extruder, extruding it from a nozzle onto a cooled cast drum and processing it into a sheet can be used, if necessary. . In the polyester film of the present invention, particles are preferably contained in the film in order to make condition 1 and condition 2 within the ranges described above. As the particles to be contained, spherical particles having a uniform particle size distribution, such as colloidal silica particles, crosslinked polystyrene particles, and calcium carbonate particles, are preferably used. The particle content is preferably 0.01% by mass or more and 3.0% by mass or less with respect to the mass of the polyester film. Moreover, the particle size of the particles is preferably 50 nm or more and 5000 nm or less. In order to satisfy condition 1, the particle size of the particles is more preferably 100 nm or more and 5000 nm or less, and particularly preferably 300 nm or more and 2000 nm or less. In order to satisfy condition 2, the particle diameter is preferably 50 nm or more and 1000 nm or less, and particularly preferably 50 nm or more and 400 nm or less. Since the raw material of the polyester film of the present invention has conditions 1 and 2 in the respective preferable ranges, the sheet to be extruded on the cast drum preferably has a laminated structure of two or more layers, and the layer constituting the A side (A It is also preferable to have a laminated structure of three or more layers having an intermediate layer (C layer) between the layers (B layer) constituting the B side. In particular, when an intermediate layer (C layer) is provided between the A layer and the B layer, it is possible to use raw materials recycled by the method described below for the C layer, which is preferable.

As a method for obtaining a sheet having a laminated structure, there is a method in which the raw materials constituting each layer are melted in separate extruders, and the layers are laminated in a preferred order in a merging device installed on a cast drum. mentioned.
It is preferable that the sheet obtained by the above method is solidified by static electricity on a drum cooled to a surface temperature of 20° C. or more and 60° C. or less to produce an unstretched sheet. The temperature of the cast drum is more preferably 20° C. or higher and 40° C. or lower, still more preferably 20° C. or higher and 30° C. or lower.

Next, the unstretched sheet is 3.6 times or more in the longitudinal direction (MD) of the film and 3.9 times or more in the width direction (TD) of the film at a temperature T1n (° C.) that satisfies the following formula (i). , preferably biaxially stretched at an area magnification of 14.0 times or more and 20.0 times or less.

The draw ratio in the film width direction is preferably 4.0 times or more, more preferably 4.3 times or more and 5.0 times or less. By setting the stretch ratio in the film width direction to 4.0 times or more, when the layer X is applied to the film after uniaxial stretching using the in-line coating method described later, the components constituting the layer X follow the film. Since it is stretched and elongated, it is possible to suppress the regular arrangement of the components constituting the layer X and to make the crystallinity of the layer X within a preferable range. If the stretch ratio in the width direction exceeds 5.0 times, the film formability of the film may deteriorate.
(i) Tg (°C) ≤ T1n (°C) ≤ Tg + 40 (°C)
Tg: Glass transition temperature of polyester film (°C)
As a method for stretching the film in the longitudinal direction, a method using a speed difference between rolls is preferably used. At this time, it is also a preferred embodiment to divide the film into a plurality of sections while fixing the film with nip rolls so that the film does not slip.

Next, the biaxially stretched film is subjected to a heat setting treatment at a temperature (Th0 (° C.)) that satisfies the following formula (ii) for 1 second or more and 30 seconds or less, uniformly slowly cooled, and then cooled to room temperature. It is preferred to obtain a polyester film by.
(ii) Tmf-35 (°C) ≤ Th0 (°C) ≤ Tmf (°C)
Tmf: Melting point of film (°C)
By obtaining a biaxially stretched film under the conditions satisfying (ii), it is possible to impart an appropriate orientation to the film and improve the handleability when used as a release film.

Next, a method for providing the layer X and the layer Y on the polyester film of the present invention will be described below.

When forming the layer X with a resin that easily absorbs water, a method of dissolving the resin forming the layer X in water and coating it on the polyester film of the present invention can be preferably used. As a coating method, general coating methods such as gravure coating, Meyer bar coating, air knife coating, and doctor knife coating can be used. In particular, from the viewpoint of controlling the crystallinity of the layer X, the surface layer of the polyester film after being uniaxially stretched in the longitudinal direction is coated with a resin that is the source of the layer X, and the polyester film is stretched in the width direction while the layer X is formed. An in-line coating method for forming a film can be preferably used.

Next, a method for providing the layer Y will be described. The layer Y may be provided simultaneously with the layer X, or may be provided separately. When they are provided at the same time, a method of applying two layers at the same time using a die or the like, or a method of applying a coating agent in which the components of the layer X and the components of the layer Y are mixed in advance can be used. In order to improve the lamination accuracy of the layers X and Y, it is preferable to provide the layers X and Y separately when the layers X and Y are provided. A general coating method such as gravure coating, Meyer bar coating, air knife coating, doctor knife coating, etc., using a coating liquid in which the components of layer Y are dissolved in the laminated polyester film containing layer X obtained by the above method. can be applied using The thickness of the layer Y is preferably 10 nm or more and 1000 nm or less. If it is 10 nm or less, the function of the layer Y may not be exhibited, and if it exceeds 1000 nm, the layer X does not exhibit sufficient water absorbency when used in combination with the layer X, |HY(1)-HY(20)| may not fall within the preferred range.

Next, a method for removing the layers X and Y will be described. Washing with water is a preferred embodiment because layer X is water absorbent. For example, a laminated film containing the polyester film of the present invention is laminated on the surface side of the layer X and the layer X from the laminated film by supplying warm water to the step of unwinding the laminated film and the surface of the unwound laminated film. It is preferable to perform the step of peeling off the member and the step of winding up the peeled polyester film. The temperature of hot water is preferably 50°C or higher and 120°C or lower. If the temperature is less than 50°C, sufficient cleaning performance may not be obtained. If it exceeds 120°C, the glass transition temperature of the polyester film is exceeded, and the film may not be transported. The time that the surface of the laminated film is in contact with water is 5 seconds or more, preferably 10 seconds or more, and more preferably 30 seconds or more and 600 seconds or less. The step of applying hot water to the surface of the unwound laminated film may be performed in a water tank to cover the entire laminated film, or a method of pressurizing heated water and spraying it onto the film. By supplying water to the layer Y of the laminated polyester film, the water is absorbed through the layer Y to the layer X and the substrate side, and as a result, the physical properties of the layer Y can be changed. As a result, the layer Y is easily peeled off from the laminated polyester film. and improve cleanability. The film transport speed is preferably 5 m/min or more, more preferably 10 m/min or more, and still more preferably 20 m/min or more and 100 m/min or less. When conveying the laminated film provided with the layer X and the layer Y in the step of removing the layer X and the layer Y, applying tension to the laminated film is also mentioned as a suitable aspect. By applying tension, the surface of the laminated film is stretched, and as a result of improving the peelability between the layers X and Y, the washability can be improved. The tension is preferably 5 N/m or more and 600 N/m or less, more preferably 20 N/m or more and 300 N/m or less, and still more preferably 30 N/m or more and 100 N/m or less. By setting the tension to 5 N/m or more, the surface of the laminated film is firmly stretched, thereby improving washability. On the other hand, by setting the tension to 600 N/m or less, deformation of the film can be suppressed, and breakage of the film during transportation can be suppressed.

Next, a method of using the film from which the layer X and the layer Y have been removed as a recycled raw material will be described. The film roll from which layer X and layer Y have been removed by the above method is introduced into a crusher having a rotating blade driven by a motor and pulverized, introduced into an extruder and melted, extruded into a strand, It is preferable to employ a method of obtaining recycled raw materials by cutting into pellets. The melting temperature is preferably 250° C. or higher and 300° C. or lower in order to keep the intrinsic viscosity of the recycled raw material in a preferable range. Moreover, the screw which an extruder has may be single-screw or twin-screw. The film from which the layers X and Y have been removed may contain particles or may contain residues from the removal of the layers X and Y. From the viewpoint of kneading, the extruder is preferably a twin screw. Moreover, it is also preferable to filter with a filter in order to adjust the components other than the polyester to an appropriate range during the melt extrusion. The recycled raw material thus obtained can be used as the raw material for the A layer, the B layer, and the C layer.

The obtained recycled raw material preferably contains 0.0001% by mass or more and 0.3% by mass or less of components other than polyester. If the amount of components other than polyester exceeds 0.3% by mass, a large amount of foreign matter is generated when a film is formed using recycled raw materials depending on the manufacturing apparatus, making it difficult to obtain desired properties. is used in the layer A or layer B of the laminated film of the present invention, the surface properties of the layer A or layer B may not be satisfied. If an attempt is made to reduce the amount of impurities so that the polyester content is less than 0.0001% by mass, the damage to the substrate film in the step of removing layer X and layer Y may increase, and recycled polyester may not be obtained. .

The recycled raw material may be used for any of the A layer, the B layer, and the C layer, but it is particularly preferable to use it for the C layer. Since the recycled raw material may contain particles contained in the laminated film as a component other than the polyester, the surface properties of the A layer and the B layer may be affected when the recycled raw material is used for the A layer and the B layer. On the other hand, when it is used for the C layer, which is an intermediate layer between the A layer and the B layer, since the C layer does not have a surface, the surface properties are not impaired when the recycled raw material is used, which is preferable.

In the polyester film of the present invention, as described above, after providing the layer X on at least one side of the polyester film, the layer Y is provided and used as a release film for the process, and the layer X and the layer Y are washed with water. can be removed to obtain a polyester film of high purity. Therefore, the obtained polyester film can be reused as it is, or the film can be remelted and chipped to be used as a recycled raw material for forming a film. In particular, as described above, by reusing it as the C layer of the film of the present invention, cyclic recycling becomes possible. From the viewpoint of film-forming properties, the recycled raw material preferably has an intrinsic viscosity (IV) of 0.5 or more and 0.7 or less, and particularly preferably 0.55 or more and 0.65 or less.

[Method for evaluating characteristics]
A. RzjisB, RzjisX (nm)
The three-dimensional surface roughness of the sample was measured using the following equipment and conditions, and the ten-point average roughness Rzjis of the surface roughness was calculated using analysis software. Let RzjisX (nm).
Apparatus: "surf-corder ET-4000A" manufactured by Kosaka Laboratory
Analysis software: i-Face model TDA31
Stylus tip radius: 0.2 μm
Measurement field of view: X direction: 380 μm Pitch: 1 μm
Y direction: 280 μm Pitch: 5 μm
Needle pressure: 50 μN
Measurement speed: 0.1mm/s
Cut-off value: low-pass; 0.8 mm, high-pass; none Leveling: All-pass filter: Gaussian filter (2D)
Magnification: 100,000 times.

B. Layer X thickness xa (nm)
Using an ion milling device IM4000 manufactured by Hitachi High-Tech Co., Ltd., the cross section of the film is exposed in the film width direction at a freezing mode and an acceleration voltage of 4 kV. The cross section is observed with a scanning electron microscope S3400N manufactured by Hitachi High-Tech Co., Ltd. at a magnification of 5000 times, and the thickness of the layer in contact with the polyester film is measured and defined as xa (nm).

C. Intrinsic viscosity (IV)
A measurement sample is dissolved in 100 ml of orthochlorophenol (solution concentration C=1.2 g/dl), and the viscosity of the solution at 25° C. is measured using an Ostwald viscometer. Also, the viscosity of the solvent is measured in the same manner. Using the obtained solution viscosity and solvent viscosity, [η] (dl/g) is calculated according to the following formula (a), and the obtained value is taken as the intrinsic viscosity (IV).
(a) ηsp/C=[η]+K[η] ²・C
(Here, ηsp=(solution viscosity (dl/g)/solvent viscosity (dl/g))−1, K is the Huggins constant (assumed to be 0.343)).

C-2. Amount of terminal carboxyl groups The amount of terminal carboxyl groups (the amount of COOH terminal groups) is determined by the method described in International Publication No. 2010/103945.

D. Copolymerization amount of layer X (mol%)
The amount of copolymerization (mol %) is determined from the peak area of the carbon signal of the introduced modifying group in the ¹³ C-NMR spectrum and DEPT135 spectrum using the following equipment.
Apparatus: ECZ-600R (manufactured by JEOL RESONANCE Co., Ltd.)
Measurement method: Single 13C pulse with inverse gated 1H decoupling
Measurement frequency: 150.9MHz
Pulse width: 5.25 μs
Lock solvent: _D2O
Chemical shift reference: TSP (0 ppm)
Cumulative number of times: 10000 times Measurement temperature: 20°C
Sample rotation speed: 15 Hz.

E. Surface free energy (mN/m)
It is measured by the following method using a contact angle meter DM501 manufactured by Kyowa Interface Science Co., Ltd. and attached analysis software FAMAS. Glycerol, ethylene glycol, formamide, and diiodomethane were used as standard liquids for the layer X surface, and the static contact angle of each liquid at 25°C was determined. The dispersion component, polar component, and hydrogen bonding component of the surface free energy of each liquid described are introduced into the "Hata and Kitazaki extended Hawks equation" described in Non-Patent Document 2, and by solving the simultaneous equations, the layer The dispersion component, polar component, and hydrogen bond component of the surface free energy of X and layer Y are obtained.

The static contact angle was measured after the sample had been allowed to stand for 12 hours in an environment of 25°C in advance. , the θ/2 method is used to calculate the static contact angle. Measurements are performed five times at different locations, and the average value of the static contact angles is used to calculate the dispersion component, polar component, and hydrogen bond component of the surface free energies of the layers X and Y.
Non-Patent Document 1: J.P. Panzer: J.P. Colloid Interface Sci. , 44, 142 (1973).
Non-Patent Document 2: Yasuaki Kitazaki, Toshio Hata: Japan Adhesive Association Paper, 8, (3) 131 (1972).
F. Water contact angle (°)
It is measured by the following method using a contact angle meter DM500 manufactured by Kyowa Interface Science Co., Ltd. and attached analysis software FAMAS. In an atmosphere of 23° C. and 65% RH, a moving image of the water droplet shape is taken for 20 seconds, with the time that the water droplet comes into contact with the sample surface as 0 seconds. Measurements were made five times at different locations, and when the sample surface in contact with the water droplet was layer X, the average contact angle obtained from the water droplet shape after 1 second and the water droplet shape after 20 seconds was calculated, and HY(1) , HY(20).

G. Peelability of the release material (barium titanate sheet) A polyester adhesive tape (No. 31B manufactured by Nitto Denko Co., Ltd., width 19 mm) was pasted on the surface of the release material of laminated polyester laminated with the release material. Then, using VPA-H200 manufactured by Kyowa Interface Science Co., Ltd., the strength of 180° peeling is measured and converted to a width of 50 mm.

H. Peelability of Releasable Material (Organic Adhesive) On the surface of the layered polyester releasable material laminated with the releasable material, a polyester film #50T60 manufactured by Toray Industries, Inc. is attached, with a width of 19 mm and a length of 300 mm. Cut it out and use it as a sample. The sample is measured for 180° peel strength using VPA-H200 manufactured by Kyowa Interface Science Co., Ltd., and converted to a width of 50 mm.

K. Removability of Layer X and Layer Y Using the polyester film obtained by removing the layer X and the layer Y, the above F. Measure the contact angle of water obtained after 1 second according to section and judge as follows.

A; 65° or more and less than 80°C B; 80° or more and 94°C or less, or less than 65° C; more than 94°.

I. Amount of components other than polyester in recycled raw materials (% by mass)
A predetermined amount of sample is dissolved in orthochlorophenol at 160° C. for 40 minutes and filtered through a glass filter (3G3). After filtration, the residue is washed with dichloromethane, dried with hot air at 130° C. for 10 hours, weighed, and the ratio of the mass of the residue to the sample before dissolution is calculated (% by mass).

J. Layer Y solvent durability (%)
It is measured by the following method using a Gakushin-type testing machine (JIS L 0849 (2013) compliant) manufactured by Daiei Kagaku Seiki Co., Ltd.
[Scraping treatment with solvent-impregnated cloth]
The layer Y surface of the film is rubbed using the following tester and rubbing element.
Testing machine: Gakushin type testing machine (Friction tester type II described in JIS L 0849 (2013))
Friction element: Cotton cloth (Kanba No. 3) impregnated with a mixed solvent of toluene and ethanol (mass ratio 1:1) Load: 1.0 kg
Number of times: 30 reciprocations [Peeling process]
A polyester adhesive tape (No. 31B manufactured by Nitto Denko Co., Ltd., width 19 mm) was adhered to the rubbed portion of the layer Y surface while being crimped with a roller of 2.0 kg, and was subjected to an atmosphere of 23 ° C. and 65% RH. After standing for 24 hours, using a peel tester VPA-H200 peel tester manufactured by Kyowa Interface Science Co., Ltd., the peel force between the sample surface and the polyester adhesive tape was measured at a peel angle of 180 ° and a peel speed of 300 mm / min. is measured and converted to a width of 50 mm to obtain F(B). The peeling force F (A) of the layer Y surface before rubbing is also measured by the same method, and the solvent durability is measured based on the following formula.
Solvent durability (%)=F(A)/F(B)×100.

EXAMPLES The present invention will be described below with reference to Examples, but the present invention is not necessarily limited to these.

[Production of PET-1] Terephthalic acid and ethylene glycol were polymerized in a conventional manner using antimony trioxide and magnesium acetate tetrahydrate as catalysts to obtain melt-polymerized PET. The resulting melt-polymerized PET had a glass transition temperature of 81° C., a melting point of 255° C., an intrinsic viscosity of 0.65, and a terminal carboxyl group content of 20 eq. /t.

[Manufacturing of MB-A] Using a 10% by mass aqueous slurry of PET-1 and crosslinked polystyrene particles (styrene/acrylate copolymer) having a particle size of 0.2 μm, 2.2. It was put into an extruder with a vent hole so that the content was 0% by mass, and kneaded while removing moisture while maintaining a reduced pressure of 1 kPa or less to obtain MB-A. The glass transition temperature is 81° C., the melting point is 255° C., the intrinsic viscosity is 0.61, and the amount of terminal carboxyl groups is 22 eq. /t.

[Preparation of MB-B] PET-1 and calcium carbonate particles with a particle size of 1.0 μm were used, and vent holes were formed at a pressure of 1 kPa or less so that 1.0% by mass of calcium carbonate particles were contained in the entire MB-B. Kneading was carried out while the degree of pressure reduction was maintained and moisture was removed to obtain MB-B. The glass transition temperature is 81° C., the melting point is 255° C., the intrinsic viscosity is 0.61, and the amount of terminal carboxyl groups is 22 eq. /t.

[Preparation of MB-C] PET-1 and alumina silicate particles with a particle size of 4.0 μm were used, and vent holes were formed at a pressure of 1 kPa or less so that the alumina silicate particles were contained in an amount of 1.0% by mass with respect to the entire MB-C. Kneading was carried out while the degree of pressure reduction was maintained and moisture was removed to obtain MB-C. The glass transition temperature is 81° C., the melting point is 255° C., the intrinsic viscosity is 0.61, and the amount of terminal carboxyl groups is 22 eq. /t.

[Preparation of coating agent A] Addition reaction type silicone resin release agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name KS-847T) 100 parts by mass, platinum catalyst (manufactured by Shin-Etsu Chemical Co., Ltd., trade name CAT-PL-50T) 1 Parts by mass were adjusted so that the solid content was 1.5% by mass using toluene as a solvent, and a coating agent A was obtained.

[Preparation of Coating Agent B] PVA having a degree of saponification of 88, an average degree of polymerization of 500, and a copolymerization amount of sodium sulfonate of 1 mol % was prepared with reference to JP-A-9-227627. The PVA was dissolved in water to a concentration of 4% by mass to obtain a coating agent B.

[Preparation of Coating Agent B-1] PVA having a degree of saponification of 88, an average degree of polymerization of 500, and a copolymerization amount of sodium sulfonate of 1 mol % was prepared with reference to JP-A-9-227627. The PVA was dissolved in water to a concentration of 10% by mass to obtain coating agent B-1.

[Preparation of coating material C] PVA having a degree of saponification of 88, an average degree of polymerization of 450, and a copolymerization amount of 1,2-ethanediol of 6 mol% was prepared with reference to JP-A-2004-285143. The PVA was dissolved in water to a concentration of 4% by mass to obtain a coating material C.

[Preparation of Adhesive D] After charging 97 parts by mass of butyl acrylate, 3 parts by mass of acrylic acid, 0.2 parts by mass of azobisisobutyronitrile as a polymerization initiator, and 233 parts by mass of ethyl acetate, nitrogen gas is flowed and the mixture is stirred. Nitrogen substitution was performed for about 1 hour. After that, the flask was heated to 60° C. and reacted for 7 hours to obtain an acrylic polymer having a weight average molecular weight (Mw) of 1,100,000. To this acrylic polymer solution (with a solid content of 100 parts by mass), 0.8 of trimethylolpropane tolylene diisocyanate (trade name “Coronate” (registered trademark) L, manufactured by Nippon Polyurethane Industry Co., Ltd.) is added as an isocyanate cross-linking agent. Parts by mass and 0.1 part by mass of a silane coupling agent (trade name “KBM-403”, manufactured by Shin-Etsu Chemical Co., Ltd.) were added to prepare an adhesive composition (coating agent D).

[Preparation of dielectric paste] 100 parts by mass of barium titanate (manufactured by Fuji Titanium Co., Ltd., product name: HPBT-1), 10 parts by mass of polyvinyl butyral (manufactured by Sekisui Chemical Co., Ltd., product name: BL-1), dibutyl phthalate 5 parts by mass and 60 parts by mass of toluene-ethanol (mass ratio 30:30), glass beads with a number average particle size of 2 mm were added, mixed and dispersed for 20 hours in a jet mill, and then filtered to form a dielectric paste. A body paste was made.

[Preparation of Coating Agent E] Polyvinyl alcohol “GL-05” manufactured by Mitsubishi Chemical Corporation (degree of saponification 88, average degree of polymerization 500) was dissolved in water to a concentration of 4% by mass to obtain coating agent E. rice field.

[Preparation of Coating Agent F] PVA having a degree of saponification of 88, an average degree of polymerization of 400, and a copolymerization amount of sodium sulfonate of 3 mol % was prepared with reference to JP-A-9-227627. The PVA was dissolved in water to a concentration of 4% by mass to obtain coating agent F.

[Preparation of Coating Agent G] PVA having a degree of saponification of 88, an average degree of polymerization of 1000, and a copolymerization amount of sodium carboxylate of 1 mol % was prepared with reference to JP-A-2008-291120. The PVA was dissolved in water to a concentration of 4% by mass to obtain a coating agent G.

[Preparation of Coating Agent H] Referring to Patent Document JP-A-2004-230772, an ethylene-propylene copolymer and an ethylene-hexene copolymer were synthesized, and 53 parts by mass of an ethylene-propylene copolymer and an ethylene-hexene copolymer were prepared. 42 parts by mass, 5 parts by mass of a nonionic surfactant (polyoxyethylene sorbitan monolaurate) ""Rheodol" (registered trademark) TW-L120" manufactured by Kao Corporation, toluene-ethyl acetate (mass ratio 85:15 ) was used as a solvent and the solid content was adjusted to 1.5% by mass to obtain a coating agent H.

(Example 1)
30 parts by mass of PET-1 and 70 parts by mass of MB-B are mixed as raw materials for the sides A and B, vacuum-dried at 160°C for 2 hours, put into an extruder, and melted at 280°C. It was extruded through a die onto a casting drum having a surface temperature of 25°C to produce an unstretched sheet. Subsequently, the sheet was preheated with a heated roll group, stretched 3.8 times in the longitudinal direction (MD direction) at a temperature of 90 ° C., and cooled with a roll group at a temperature of 25 ° C. to obtain a uniaxially stretched film. got On the A side of the obtained uniaxially stretched film, the coating agent B was applied by a bar coating method so that the coating thickness after drying and stretching was 100 nm, and then the film was held at both ends with clips. The film was stretched 4.3 times in the width direction (TD direction) perpendicular to the longitudinal direction in a heating zone at a temperature of 100°C. Subsequently, heat setting was performed at a temperature of 230° C. for 10 seconds in a heat treatment zone in the tenter. Then, after uniformly slow cooling in a cooling zone, the film was wound into a roll to obtain a laminated polyester film in which the layer X was laminated. Using a part of the obtained laminated polyester film in which the layer X is laminated, a layer Y having a thickness of 0.1 μm is applied to the upper surface of the layer X (the surface opposite to the surface where the layer X contacts the polyester film). A laminated polyester film in which layer X and layer Y were laminated was obtained. The properties of layer Y of the resulting laminated polyester film in which layer X and layer Y were laminated were as shown in the table. Furthermore, using the laminated polyester film in which the layer X and the layer Y thus produced are laminated as a release film, a dielectric The body paste was applied by a die coating method so that the thickness after drying was 1.0 μm. After that, from the obtained laminate, a release film roll for a process was obtained in which the dielectric was released and the material to be released was peeled off. The film roll was introduced into a water washing device with an unwinding and winding device and washed with water at 60° C. for 2 minutes under a tension of 100 N/m to remove layer X and layer Y. Table 2 shows the properties of the release film.

In addition, the remainder of the obtained laminated polyester film laminated with the layer X was wrapped in a moisture-proof packing material (aluminum tube manufactured by Nagaoka Sangyo Co., Ltd.) in a roll form and kept at 60 ° C. and a relative humidity of 80% for 7 days. left undisturbed. After that, the laminated polyester film on which the layer X is laminated is taken out, and the surface of the layer X opposite to the surface in contact with the polyester film is coated with a coating agent A so that the layer Y has a thickness of 0.1 μm by a gravure coating method. to obtain a laminated polyester film in which layer X and layer Y are laminated. The properties of the layer Y of the laminated polyester film in which the layer X and the layer Y thus obtained are laminated are shown in Table 3 as the laminated polyester film after wet heat treatment. Furthermore, using the laminated polyester film in which the layer X and the layer Y thus produced are laminated as a release film, a dielectric The body paste was applied by a die coating method so that the thickness after drying was 1.0 μm. After that, from the obtained laminate, a release film roll for a process was obtained in which the dielectric was released and the material to be released was peeled off. The film roll was introduced into a water washing device with an unwinding and winding device and washed with water at 60° C. for 2 minutes under a tension of 100 N/m to remove layer X and layer Y. The properties of the release film at that time are shown in Table 3 as a release film using the laminated polyester film after wet heat treatment.

A release film using a laminated film having layer X when not stored in a moist and heat atmosphere, and a release film using a laminated film having layer X after storage in a moist and heat atmosphere (lamination after moist heat treatment The removability of layer X and layer Y of the release film using a polyester film was at a practically acceptable level, and there was no problem in use as a release film.

(Example 2)
Laminated polyester film in which layer X was laminated in the same manner as in Example 1, except that the thickness of layer X was as shown in the table, polyester film in which layer X and layer Y were laminated, release film, after wet heat treatment and a release film using the laminated polyester film after wet heat treatment. Each characteristic is shown in Tables 2 and 3.
A release film using a laminated film having layer X when not stored in a moist and heat atmosphere, and a release film using a laminated film having layer X after storage in a moist and heat atmosphere (lamination after moist heat treatment The removability of layer X and layer Y of the release film using a polyester film was at a practically acceptable level, and there was no problem in use as a release film.

(Example 3)
95 parts by mass of PET-1 and 5 parts by mass of MB-A were mixed as the raw material for the A side and vacuum-dried at 160 ° C. for 2 hours, and 50 parts by mass of PET-1 and MB- 50 parts by mass of B are mixed, the raw materials vacuum dried at 160 ° C. for 2 hours are put into separate extruders, melted at 280 ° C., and passed through a confluence device to determine the thickness of the layer (A layer) constituting the A side. After lamination so that the thickness of the layer constituting the B side (B layer) was 5/95, it was extruded through a die onto a casting drum having a surface temperature of 25° C. to prepare an unstretched sheet. Subsequently, the sheet was preheated with a heated roll group, stretched 3.8 times in the longitudinal direction (MD direction) at a temperature of 90 ° C., and cooled with a roll group at a temperature of 25 ° C. to obtain a uniaxially stretched film. got On the A side of the obtained uniaxially stretched film, the coating agent B was applied by a bar coating method so that the coating thickness after drying and stretching was 100 nm, and then the film was held at both ends with clips. The film was stretched 4.3 times in the width direction (TD direction) perpendicular to the longitudinal direction in a heating zone at a temperature of 100°C. Subsequently, heat setting was performed at a temperature of 230° C. for 10 seconds in a heat treatment zone within the tenter. Then, after uniformly slow cooling in a cooling zone, the film was wound into a roll to obtain a laminated polyester film in which the layer X was laminated. The properties of the resulting laminated polyester film laminated with the layer X were as shown in the table.

Next, using a part of the obtained laminated polyester film, a layer Y having a thickness of 0.1 μm is formed on the surface opposite to the surface in contact with the polyester film of the layer X of the laminated polyester film in which the layer X is laminated. Coating agent A was applied by a gravure coating method to obtain a laminated polyester film in which layer X and layer Y were laminated. The properties of Layer Y were met as described in Table 2.

In addition, the laminated polyester film laminated with the remaining layer X described above is wrapped in a moisture-proof packing material (aluminum tube manufactured by Nagaoka Sangyo Co., Ltd.) in a roll shape, and left to stand for 7 days in an atmosphere of 60 ° C. and a relative humidity of 80%. did. After that, the laminated polyester film on which the layer X is laminated is taken out, and the surface of the layer X opposite to the surface in contact with the polyester film is coated with a coating agent A so that the layer Y has a thickness of 0.1 μm by a gravure coating method. to obtain a laminated polyester film in which layer X and layer Y are laminated. The properties of the layer Y of the laminated polyester film in which the layer X and the layer Y thus obtained are laminated are shown in Table 3 as the laminated polyester film after wet heat treatment. Using the laminated polyester film in which the layer X and the layer Y thus prepared are laminated as a release film, a dielectric paste is applied as a release material on the surface of the layer Y opposite the surface in contact with the layer X. was applied by a die coating method so that the thickness after drying was 1.0 μm. After that, from the obtained laminate, a release film roll for a process was obtained in which the dielectric was released and the material to be released was peeled off. The film roll was introduced into a water washing device with an unwinding and winding device and washed with water at 60° C. for 2 minutes under a tension of 100 N/m to remove layer X and layer Y. The properties of the release film at that time are shown in Table 3 as a release film using the laminated polyester film after wet heat treatment.

A release film using a laminated film having layer X when not stored in a moist and heat atmosphere, and a release film using a laminated film having layer X after storage in a moist and heat atmosphere (lamination after moist heat treatment The removability of the layers X and Y of the release film using a polyester film was excellent, and the film was also excellent as a release film.

(Example 4)
A laminated polyester film in which layer X was laminated in the same manner as in Example 3, except that the constituent components of layer X and the thickness of layer X were changed as shown in the table, and a polyester film in which layer X and layer Y were laminated. , a release film, a laminated polyester film after wet heat treatment, and a release film using the laminated polyester film after wet heat treatment were obtained. Each characteristic is shown in the table.
A release film using a laminated film having layer X when not stored in a moist and heat atmosphere, and a release film using a laminated film having layer X after storage in a moist and heat atmosphere (lamination after moist heat treatment The removability of layer X and layer Y of the release film using a polyester film was at a practically acceptable level, and there was no problem in use as a release film.

(Example 5)
The raw material for side A is a mixture of 95 parts by mass of PET-1 and 5 parts by mass of MB-A, and the raw material for side B is a mixture of 10 parts by mass of PET-1 and 90 parts by mass of MB-C. Laminated polyester film in which layer X was laminated in the same manner as in Example 3, polyester film in which layer X and layer Y were laminated, release film, laminated polyester film after wet heat treatment, laminated polyester after wet heat treatment A release film using the film was obtained. Each characteristic is shown in the table.

A release film using a laminated film having layer X when not stored in a moist and heat atmosphere, and a release film using a laminated film having layer X after storage in a moist and heat atmosphere (lamination after moist heat treatment The removability of the layers X and Y of the release film using a polyester film was excellent, and the film was also excellent as a release film.

(Example 6)
In Example 3, the pressure-sensitive adhesive D was used as the release material, and was applied by a die coating method so that the thickness after drying was 10 μm. After that, from the obtained laminate, the pressure-sensitive adhesive D was released, and a release film roll for a process in which the material to be released was released was obtained. The film roll was introduced into a water washing device with an unwinding and winding device and washed with water at 60° C. for 2 minutes under a tension of 100 N/m to remove layer X and layer Y. The properties of the polyester film in which layer X and layer Y are laminated, the release film, the laminated polyester film after wet heat treatment, and the release film using the laminated polyester film after wet heat treatment are shown in the table.

A release film using a laminated film having layer X when not stored in a moist and heat atmosphere, and a release film using a laminated film having layer X after storage in a moist and heat atmosphere (lamination after moist heat treatment The removability of the layers X and Y of the release film using a polyester film was excellent, and the film was also excellent as a release film.

(Example 7)
95 parts by mass of PET-1 and 5 parts by mass of MB-A were mixed as the raw material for the A side and vacuum-dried at 160 ° C. for 2 hours, and 50 parts by mass of PET-1 and MB- 50 parts by mass of B are mixed and vacuum-dried at 160 ° C. for 2 hours, and the intermediate layer (C layer) between the layer (A layer) constituting the A side and the layer (B layer) constituting the B side. As a raw material, PET-1 was vacuum-dried at 160°C for 2 hours. The raw materials were put into separate extruders, melted at 280°C, and laminated in the order of A layer/C layer/B layer through a confluence device. After lamination so that each layer had a thickness of 5/90/5, it was extruded through a die onto a casting drum having a surface temperature of 25° C. to prepare an unstretched sheet. Subsequently, the sheet was preheated with a heated roll group, stretched 3.8 times in the longitudinal direction (MD direction) at a temperature of 90 ° C., and cooled with a roll group at a temperature of 25 ° C. to obtain a uniaxially stretched film. got The resulting uniaxially stretched film was coated with the coating material B by a bar coating method so that the coating thickness after drying and stretching was 100 nm, and then the film was held at both ends with clips at 100 ° C. in a tenter. The film was stretched 4.3 times in the width direction (TD direction) perpendicular to the longitudinal direction in a heating zone at a temperature of . Subsequently, heat setting was performed at a temperature of 230° C. for 10 seconds in a heat treatment zone within the tenter. Then, after uniformly slow cooling in a cooling zone, the film was wound into a roll to obtain a laminated polyester film in which the layer X was laminated. The properties of the resulting laminated polyester film laminated with the layer X were as shown in the table.

Next, using a part of the obtained laminated polyester film, a layer Y having a thickness of 0.1 μm is formed on the surface opposite to the surface in contact with the polyester film of the layer X of the laminated polyester film in which the layer X is laminated. Coating agent A was applied by a gravure coating method to obtain a laminated polyester film in which layer X and layer Y were laminated. The properties of layer Y were as described in the table.
In addition, the laminated polyester film laminated with the remaining layer X described above is wrapped in a moisture-proof packing material (aluminum tube manufactured by Nagaoka Sangyo Co., Ltd.) in a roll shape, and left to stand for 7 days in an atmosphere of 60 ° C. and a relative humidity of 80%. did. After that, the laminated polyester film on which the layer X is laminated is taken out, and the surface of the layer X opposite to the surface in contact with the polyester film is coated with a coating agent A so that the layer Y has a thickness of 0.1 μm by a gravure coating method. to obtain a laminated polyester film in which layer X and layer Y are laminated. The properties of the layer Y of the laminated polyester film in which the layer X and the layer Y thus obtained are laminated are shown in Table 3 as the laminated polyester film after wet heat treatment. Furthermore, using the laminated polyester film in which the layer X and the layer Y thus produced are laminated as a release film, a dielectric The body paste was applied by a die coating method so that the thickness after drying was 1.0 μm. After that, from the obtained laminate, a release film roll for a process was obtained in which the dielectric was released and the material to be released was peeled off. The film roll was introduced into a water washing device with an unwinding and winding device and washed with water at 60° C. for 2 minutes under a tension of 100 N/m to remove layer X and layer Y. The properties of the release film at that time are shown in Table 3 as a release film using the laminated polyester film after wet heat treatment.

A release film using a laminated film having layer X when not stored in a moist and heat atmosphere, and a release film using a laminated film having layer X after storage in a moist and heat atmosphere (lamination after moist heat treatment The removability of the layers X and Y of the release film using a polyester film was excellent, and the film was also excellent as a release film.

(Example 8)
Laminated polyester film in which layer X was laminated in the same manner as in Example 3 except that the constituent components of layer X were as described in the table, polyester film in which layer X and layer Y were laminated, release film, wet heat treatment A release film using the laminated polyester film after the lamination and the laminated polyester film after the wet heat treatment was obtained. Each characteristic is shown in the table.

In Example 8, the surface free energies γXP and γXH of the layer X were out of the preferred ranges, so that the peel strength of the film laminated with the layer Y was somewhat high, but it was within a practically acceptable range.

A release film using a laminated film having layer X when not stored in a moist and heat atmosphere, and a release film using a laminated film having layer X after storage in a moist and heat atmosphere (lamination after moist heat treatment The removability of the layer X and the layer Y of the release film using a polyester film was excellent, and it was in a range where there was no practical problem as a release film.
(Reference example 1)
The polyester film obtained in Example 3 from which layer X and layer Y were removed was cut, put into an extruder with a vent hole, and extruded at 280 ° C. while removing moisture while maintaining a vacuum of 1 kPa or less to pellet. Recycled raw material-1 was obtained by processing into a shape. The recycled raw material has a glass transition temperature of 81° C., a melting point of 255° C., an intrinsic viscosity of 0.58, and a terminal carboxyl group content of 28 eq. /t. The amount of components other than polyester contained in the recycled raw material was 0.47% by mass.

(Reference example 2)
The polyester film obtained in Example 7 from which layer X and layer Y were removed was cut, put into an extruder with a vent hole, and extruded at 280 ° C. while removing moisture while maintaining a vacuum of 1 kPa or less to pellet. Recycled raw material-2 was obtained by processing into a shape. The recycled raw material has a glass transition temperature of 81° C., a melting point of 255° C., an intrinsic viscosity of 0.58, and a terminal carboxyl group content of 28 eq. /t. The amount of components other than polyester contained in the recycled raw material was 0.03% by mass.

(Example 9)
95 parts by mass of PET-1 and 5 parts by mass of MB-A were mixed as the raw material for the A side and vacuum-dried at 160 ° C. for 2 hours, and 50 parts by mass of PET-1 and MB- 50 parts by mass of B are mixed and vacuum-dried at 160 ° C. for 2 hours, and the intermediate layer (C layer) between the layer (A layer) constituting the A side and the layer (B layer) constituting the B side. As a raw material, 50 parts by mass of PET-1 and 50 parts by mass of the recycled raw material obtained in Reference Example 1 were mixed, and the raw material was vacuum-dried at 160 ° C. for 2 hours, and layer X was laminated in the same manner as in Example 6. Laminated polyester A film, a polyester film in which layer X and layer Y are laminated, a release film, a laminated polyester film after wet heat treatment, and a release film using the laminated polyester film after wet heat treatment were obtained. Each characteristic is shown in the table.

A release film using a laminated film having layer X when not stored in a moist and heat atmosphere, and a release film using a laminated film having layer X after storage in a moist and heat atmosphere (lamination after moist heat treatment The removability of the layers X and Y of the release film using a polyester film was excellent, and the film was also excellent as a release film.

(Examples 10-12)
Laminated polyester film in which layer X was laminated in the same manner as in Example 3, except that the coating agent was changed as shown in the table, polyester film in which layer X and layer Y were laminated, release film, after wet heat treatment A laminated polyester film and a releasing film using the laminated polyester film after wet heat treatment were produced. Each characteristic is shown in the table.

In Examples 10 and 12, the surface free energies γXP and γXH of the layer X were out of the preferred range, so the peeling strength of the film laminated with the layer Y was somewhat high, but it was within a practically acceptable range. In addition, the size |HY(1)-HY(20)| of the layer Y was slightly small, and although the removability of the layer Y was inferior, it was within a practically acceptable range.

In Examples 10 and 12, the removability of the layer X and the layer Y of the release film using the laminated film having the layer X after storage in a moist heat atmosphere was within a practically acceptable range.
In Example 11, γXP and γXH are within preferable ranges, |HY(1)-HY(20)| and the release film layer X of the release film using a laminated film having layer X after being stored in a moist heat atmosphere, excellent in removability of layer Y, and also excellent as a release film It was something.

(Example 13)
85 parts by mass of PET-1, 5 parts by mass of MB-A, and 10 parts by mass of the recycled raw material-1 obtained in Reference Example 1 were mixed as the raw material constituting the A side, and the raw material was vacuum-dried at 160 ° C. for 2 hours, B side. 50 parts by mass of PET-1 and 50 parts by mass of MB-B are mixed as a raw material constituting the , and the raw material is vacuum dried at 160 ° C. for 2 hours, and a layer constituting the A side (A layer) and a layer constituting the B side Layer X is laminated in the same manner as in Example 6 using a raw material obtained by vacuum drying 100 parts by mass of PET-1 at 160 ° C. for 2 hours as a raw material for the intermediate layer (C layer) with (B layer). , a polyester film in which layer X and layer Y are laminated, a release film, a laminated polyester film after wet heat treatment, and a release film using the laminated polyester film after wet heat treatment were obtained. Each characteristic is shown in the table.

Since the recycled raw material-1 obtained in Reference Example 1 used for the A layer contains a slightly large amount of components other than polyester, the RzjisX/xa is slightly large, and the laminated film having a layer X when not stored in a moist and hot atmosphere. and a release film using a laminated film having a layer X after storage in a moist heat atmosphere (a release film using a laminated polyester film after wet heat treatment) Layer X, Although the removability of the layer Y was slightly inferior, there was no practical problem.

(Example 14)
85 parts by mass of PET-1, 5 parts by mass of MB-A, and 10 parts by mass of the recycled raw material-1 obtained in Reference Example 1 were mixed as the raw material constituting the A side, and the raw material was vacuum-dried at 160 ° C. for 2 hours, B side. 10 parts by mass of PET-1, 40 parts by mass of MB-B, and 10 parts by mass of the recycled raw material-1 obtained in Reference Example 1 were mixed as raw materials constituting the , and the raw material was vacuum-dried at 160 ° C. for 2 hours. 100 parts by mass of PET-1 was vacuum-dried at 160 ° C. for 2 hours as a raw material for the intermediate layer (C layer) between the constituting layer (A layer) and the layer (B layer) constituting the B side. A laminated polyester film in which layer X was laminated in the same manner as in Example 6, a polyester film in which layer X and layer Y were laminated, a release film, a laminated polyester film after wet heat treatment, and a laminated polyester film after wet heat treatment were used. A release film was obtained. Each characteristic is shown in the table.

Since the recycled raw material-1 obtained in Reference Example 1 used for the A layer contains a slightly large amount of components other than polyester, RzjisB/xa is in a preferable range, but RzjisX/xa is slightly large, and in a moist and hot atmosphere A release film using a laminated film having layer X when not stored, and a release film using a laminated film having layer X after being stored in a moist heat atmosphere (using a laminated polyester film after wet heat treatment Although the removability of layer X and layer Y of the release film) was slightly inferior, there was no practical problem.

(Example 15)
85 parts by mass of PET-1, 5 parts by mass of MB-A, and 10 parts by mass of the recycled raw material-1 obtained in Reference Example 1 were mixed as the raw material constituting the A side, and the raw material was vacuum-dried at 160 ° C. for 2 hours, B side. 10 parts by mass of PET-1, 40 parts by mass of MB-B, and 10 parts by mass of the recycled raw material-1 obtained in Reference Example 1 were mixed as raw materials constituting the , and the raw material was vacuum-dried at 160 ° C. for 2 hours. 50 parts by mass of PET-1 and 50 parts by mass of the recycled raw material-1 obtained in Reference Example 1 as raw materials for the intermediate layer (C layer) between the layer (A layer) and the layer (B layer) that constitutes the B side Using a raw material vacuum dried at 160 ° C. for 2 hours, a laminated polyester film in which layer X is laminated in the same manner as in Example 6, a polyester film in which layer X and layer Y are laminated, a release film, after wet heat treatment A laminated polyester film and a release film using the laminated polyester film after wet heat treatment were obtained. Each characteristic is shown in the table.

Since the recycled raw material-1 obtained in Reference Example 1 used for the A layer contains a slightly large amount of components other than polyester, RzjisB/xa is in a preferable range, but RzjisX/xa is slightly large, and in a moist and hot atmosphere A release film using a laminated film having layer X when not stored, and a release film using a laminated film having layer X after being stored in a moist heat atmosphere (using a laminated polyester film after wet heat treatment Although the removability of layer X and layer Y of the release film) was slightly inferior, there was no practical problem.

(Example 16)
85 parts by mass of PET-1, 5 parts by mass of MB-A, and 10 parts by mass of the recycled raw material-1 obtained in Reference Example 1 were mixed as the raw material constituting the A side, and the raw material was vacuum-dried at 160 ° C. for 2 hours, B side. 50 parts by mass of PET-1 and 50 parts by mass of MB-B are mixed as a raw material constituting the , and the raw material is vacuum dried at 160 ° C. for 2 hours, and a layer constituting the A side (A layer) and a layer constituting the B side Layer X is laminated in the same manner as in Example 6 using a raw material obtained by vacuum drying 100 parts by mass of PET-1 at 160 ° C. for 2 hours as a raw material for the intermediate layer (C layer) with (B layer). , a polyester film in which layer X and layer Y are laminated, a release film, a laminated polyester film after wet heat treatment, and a release film using the laminated polyester film after wet heat treatment were obtained. Each characteristic is shown in the table.

The components other than the polyester contained in the recycled raw material-2 obtained in Reference Example 2 used for the A layer are in the preferable range, and the RzjisX/xa is in the preferable range, and the layer X is obtained when not stored in a moist and hot atmosphere. A layer of a release film using a laminated film and a release film using a laminated film having a layer X after being stored in a moist heat atmosphere (a release film using a laminated polyester film after wet heat treatment) It was excellent in removability of X and layer Y, and was also excellent as a release film.

(Example 17)
30 parts by mass of PET-1 and 20 parts by mass of MB-B are mixed as raw materials for the sides A and B, vacuum-dried at 160°C for 2 hours, put into an extruder, and melted at 280°C. It was extruded through a die onto a casting drum having a surface temperature of 25°C to produce an unstretched sheet. Subsequently, the sheet was preheated with a heated roll group, stretched 3.8 times in the longitudinal direction (MD direction) at a temperature of 90 ° C., and cooled with a roll group at a temperature of 25 ° C. to obtain a uniaxially stretched film. got Subsequently, while holding both ends of the film with clips, the film was stretched 4.3 times in the width direction (TD direction) perpendicular to the longitudinal direction in a heating zone at a temperature of 100° C. in the tenter. Subsequently, heat setting was performed at a temperature of 230° C. for 10 seconds in a heat treatment zone within the tenter. Then, after uniformly slow cooling in a cooling zone, the film was wound into a roll to obtain a polyester film. Using a part of the obtained polyester film, a layer Y was coated by a gravure coating method using a coating agent H so that the layer Y had a thickness of 0.1 μm, thereby obtaining a laminated polyester film in which the layer Y was laminated. The properties of the layer Y of the resulting laminated polyester film laminated with the layer Y were as shown in the table. Furthermore, the laminated polyester film laminated with the layer Y thus prepared is used as a release film, and a dielectric paste is applied as a release material on the surface of the layer Y opposite to the surface in contact with the polyester film. It was applied by a die coating method so that the thickness after drying was 1.0 μm. After that, from the obtained laminate, a release film roll for a process was obtained in which the dielectric was released and the material to be released was peeled off. The film roll was introduced into a water washing device with an unwinding and winding device and washed with water at 60° C. for 2 minutes under a tension of 100 N/m to remove the layer Y. The properties of the release film are shown in the table.

The remainder of the obtained polyester film is wrapped in a moisture-proof packing material (aluminum tube manufactured by Nagaoka Sangyo Co., Ltd.) in a roll form and allowed to stand in an atmosphere of 60° C. and a relative humidity of 80% for 7 days. After that, the polyester film was taken out, and a layer Y was coated with a coating material H by gravure coating so as to have a thickness of 0.1 μm, thereby obtaining a laminated polyester film in which the layer Y was laminated. The properties of the layer Y of the resulting laminated polyester film laminated with the layer Y were as shown in the table. Furthermore, the laminated polyester film laminated with the layer Y thus prepared is used as a release film, and a dielectric paste is applied as a release material on the surface of the layer Y opposite to the surface in contact with the polyester film. It was applied by a die coating method so that the thickness after drying was 1.0 μm. After that, from the obtained laminate, a release film roll for a process was obtained in which the dielectric was released and the material to be released was peeled off. The film roll was introduced into a water washing device with an unwinding and winding device and washed with water at 60° C. for 2 minutes under a tension of 100 N/m to remove the layer Y.

The removability of the layer Y of the release film and the release film using a polyester film after storage in a moist and heat atmosphere (releasing film using a laminated polyester film after wet heat treatment) is a practical problem. There was no problem in use as a release film.

(Comparative Examples 1 to 3)
In Comparative Example 1, 95 parts by mass of PET-1 and 5 parts by mass of MB-A were used as raw materials for forming the A side and the B side, and in Comparative Example 2, PET was used as the raw material for forming the A side and the B side. -1, and in Comparative Example 3, 30 parts by mass of PET-1 and 70 parts by mass of MB-C were used as the raw materials constituting the A side and the B side. Layer X in the same manner as in Example 1 was laminated, a polyester film in which layer X and layer Y were laminated, a release film, a laminated polyester film after wet heat treatment, and a release film using the laminated polyester film after wet heat treatment were obtained. Each characteristic is shown in the table.

Although there was no problem in the removability of layer X and layer Y of the release film using the laminated film having layer X when not stored in a moist and heat atmosphere, layer X after storage in a moist and heat atmosphere. The release film using the laminated film (releasing film using the laminated polyester film after wet heat treatment) is inferior in removability of the layers X and Y, and the release film can also be used as a release film. It was a film with inferior properties.

(Comparative Example 4)
50 parts by mass of PET-1 and 50 parts by mass of MB-B were mixed as the raw material for the A side, and the raw material was vacuum dried at 160 ° C. for 2 hours, and 95 parts by mass of PET-1 and MB- A laminated polyester film in which layer X was laminated in the same manner as in Example 3, except that 5 parts by mass of A were mixed and vacuum dried at 160 ° C. for 2 hours, and a polyester film in which layer X and layer Y were laminated , a release film, a laminated polyester film after wet heat treatment, and a release film using the laminated polyester film after wet heat treatment were obtained. Each characteristic is shown in the table.

The removability of layer X and layer Y of the release film using the laminated film having layer X when not stored in a moist and hot atmosphere is slightly inferior, and the laminated film having layer X after storage in a moist and hot atmosphere (wet A release film using a laminated polyester film after heat treatment) is inferior in the removability of layers X and Y of the release film, and is a film that is inferior in releasability of the material to be released as a release film. there were.

(Comparative Example 5)
On one side (Side A) of Toray Co., Ltd.'s polyester film "Lumirror" (registered trademark) #50T60, the coating material B is applied by a gravure coating method so that the coating thickness after drying is 100 nm, and is formed into a roll shape. The film was taken up to obtain a laminated polyester film in which the layer X was laminated. The properties of the resulting laminated polyester film laminated with the layer X were as shown in the table.

Next, using a part of the obtained laminated polyester film, a layer Y having a thickness of 0.1 μm is formed on the surface opposite to the surface in contact with the polyester film of the layer X of the laminated polyester film in which the layer X is laminated. Coating agent A was applied by a gravure coating method to obtain a laminated polyester film in which layer X and layer Y were laminated. The properties of layer Y were as described in the table.

In addition, the laminated polyester film laminated with the remaining layer X described above is wrapped in a moisture-proof packing material (aluminum tube manufactured by Nagaoka Sangyo Co., Ltd.) in a roll shape, and left to stand for 7 days in an atmosphere of 60 ° C. and a relative humidity of 80%. did. After that, the laminated polyester film on which the layer X is laminated is taken out, and the surface of the layer X opposite to the surface in contact with the polyester film is coated with a coating agent A so that the layer Y has a thickness of 0.1 μm by a gravure coating method. to obtain a laminated polyester film in which layer X and layer Y are laminated. The properties of the layer Y of the laminated polyester film in which the layer X and the layer Y thus obtained are laminated are shown in the table as the laminated polyester film after wet heat treatment. Using the laminated polyester film in which the layer X and the layer Y thus prepared are laminated as a release film, a dielectric paste is applied as a release material on the surface of the layer Y opposite the surface in contact with the layer X. was applied by a die coating method so that the thickness after drying was 1.0 μm. After that, from the obtained laminate, a release film roll for a process was obtained in which the dielectric was released and the material to be released was peeled off. The film roll was introduced into a water washing device with an unwinding and winding device and washed with water at 60° C. for 2 minutes under a tension of 100 N/m to remove layer X and layer Y.

Although there was no problem in the removability of layer X and layer Y of the release film using the laminated film having layer X when not stored in a moist and heat atmosphere, layer X after storage in a moist and heat atmosphere. The release film using the laminated film (releasing film using the laminated polyester film after wet heat treatment) is inferior in removability of the layers X and Y, and the release film can also be used as a release film. It was a film with inferior properties.

(Comparative Example 6)
A release film was produced in the same manner as in Example 17, except that layer Y had the composition shown in the table. The value of |HY(1)-HY(20)| was small, and the film was inferior in layer Y removability.

Regarding the examples, if there is a discrepancy between the description in the specification and the description in the table, the description in the table takes precedence.

The laminated polyester film of the present invention has excellent storability in a hot and humid atmosphere, and excellent removability of layers other than the polyester film. In addition, by using a water-repellent material for the layer Y of the present invention, it can be suitably used as a release film for the manufacturing process of a multilayer ceramic capacitor (MLCC) using a dielectric paste as a release material. In addition, since the polyester film can be easily recovered from the release film after being used in the MLCC manufacturing process, the polyester film can be easily reused as a raw material for melt film formation.

Claims (16)

A laminated polyester film having a polyester film and a hydrophilic layer X, wherein the thickness xa (nm) of the layer X and the surface (A surface) of the polyester film on the side opposite to the layer X A laminated polyester film whose surface roughness RzjisB (nm) on the surface (B surface) side satisfies the following condition 1.
Condition 1: 1.5≤RzjisB/xa≤10.0 The laminated polyester film according to claim 1, wherein the thickness xa (nm) of the layer X and the surface roughness RzjisX (nm) of the layer X satisfy Condition 2 below.
Condition 2: 0.01≤RzjisX/xa≤3.0 3. The laminated polyester film according to claim 1, wherein the layer X has a thickness xa of 10 nm or more and 500 nm or less. 4. The laminated polyester film according to any one of claims 1 to 3, wherein the surface free energy of the layer X satisfies the following conditions.
Condition 3: 20≦γX _P ≦30
Condition 4: _{6.0≤γXH≤10}
γX _P (mN/m): Polar component of surface free energy of layer X γX _H (mN/m): Hydrogen bonding component of surface free energy of layer X 5. The laminated polyester film according to any one of claims 1 to 4, which has a layer Y satisfying the following conditions, the layer X, and a polyester film in this order.
Condition 3: 80≤HY(1)≤120
Condition 4: 5≤|HY(1)-HY(20)|≤90
HY (1) (°): contact angle 1 second after water contacts layer Y HY (20) (°): contact angle 20 seconds after water contacts layer Y The layer Y is in contact with the layer X, and a release layer is provided on the surface of the layer Y opposite to the surface in contact with the layer X, and the release layer is peeled off from the layer Y. Item 6. The laminated polyester film according to item 5. 7. The laminated polyester film according to claim 6, which is used for applications in which the layer X and the layer Y are removed after the release layer is peeled from the layer Y. 8. The laminated polyester film according to claim 7, which is used for reuse of the laminated polyester film from which the layers X and Y have been removed. The laminated polyester film according to any one of claims 6 to 8, wherein the release layer is a ceramic green sheet containing barium titanate as a main component. 10. The laminated polyester film according to any one of claims 1 to 9, which is used as a release film for manufacturing processes of laminated ceramic capacitors (MLCC). 9. The laminated polyester film according to any one of claims 6 to 8, wherein the release layer is a pressure-sensitive adhesive containing an acrylic resin as a main component. 12. The laminated polyester film according to any one of claims 1 to 8 and 11, which is used as a release film for a polarizing plate manufacturing process. The polyester film has a laminated structure of three or more layers having a layer (A layer) constituting the A side, a layer (B layer) constituting the B side, and an intermediate layer (C layer), 13. The laminated polyester film according to any one of claims 1 to 12, wherein any one or all of the A layer, the B layer, and the C layer contain a recycled polyester raw material. The polyester film has a laminated structure of three or more layers having a layer (A layer) constituting the A side, a layer (B layer) constituting the B side, and an intermediate layer (C layer), 14. The laminated polyester film according to any one of claims 1 to 13, wherein the C layer comprises recycled polyester raw material. Using the laminated polyester film according to any one of claims 1 to 14, which has at least a release layer, a layer Y, and a polyester film in this order, a step of peeling the release layer from the layer Y; The method includes a step of removing the layer Y from the film from which the mold layer has been peeled off, a step of producing a recycled raw material from the film from which the release layer and the layer Y have been removed, and a step of forming a film using the recycled raw material. A method for producing a polyester film. A laminated polyester film comprising a polyester film and a layer Y, wherein the water contact angles HY(1) (°) and HY(20) (°) of the layer Y satisfy the following equations.
80≤HY(1)≤120, 5≤|HY(1)-HY(20)|≤90
HY (1) (°): contact angle 1 second after water contacts layer Y HY (20) (°): contact angle 20 seconds after water contacts layer Y