JP2023039591A - laminated polyester film - Google Patents

Abstract

To provide a biaxially oriented polyester film that has a highly smooth surface, good releasability, and excellent adhesion property with a polyester resin layer being a substrate.SOLUTION: A laminated polyester film has a polyester film and a mold releasable resin layer (P1) in which the mold releasable resin layer (P1) is on at least one surface layer, and fulfills the following requirements (1) to (3). (1) In the case where the surface of the mold releasable resin layer (P1) is face A, and the arithmetic average roughness of the face A is SaA (nm), SaA is 0.5 or more and 4.5 or less. (2) In the case where protrusions are present on the surface of the face A, the number of protrusions having the height of 50nm or more is N50nmA (pcs./mm2), N50nmA is 200 or less. (3) In the case where the water contact angle of the face A is CaA(°), CaA is 90 or more and 120 or less.SELECTED DRAWING: None

Description

The present invention relates to a laminated polyester film.

Thermoplastic resins are used in various industrial fields because of their good workability. Products obtained by processing these thermoplastic resins into films play an important role in today's life, such as industrial applications, optical product applications, packaging applications, and magnetic recording tape applications. In recent years, electronic information equipment has become smaller, finer, and more highly integrated, and along with this, there is a demand for improved workability of process films used in the manufacturing process of electronic information equipment.

As a process film for manufacturing electronic parts, polyester film having a release function coating layer is used, especially for forming an interlayer insulation layer on an electronic substrate, and a hydrophilic resin layer such as epoxy resin is applied on the release coating surface. For example, a step of peeling off the polyester film with a release function after forming and bonding to the electronic substrate can be exemplified. When the unevenness of the release coat surface is transferred to the surface of the hydrophilic resin layer such as epoxy resin, unevenness occurs in the copper foil layer provided thereon, and the transmission loss with the electric wiring increases. In addition, in the application of laminated ceramic capacitors, there is a process of forming a thin ceramic layer called a green sheet on the release coating surface of the polyester film with a release function and peeling it off. Once transferred, defects due to the uneven shape occur in the subsequent step of laminating the green sheets.

Furthermore, when these polyester films have a release coat layer, the adhesion between the polyester film and the release coat layer is very important. If the adhesiveness to the polyester film is poor, the release coat layer remains on the mating member as a foreign matter, and the release coat layer falls off due to friction with the transport roll during process transport, causing process contamination.

For this reason, the laminated polyester film with a release coat layer used in the above process not only has good releasability from the mating member, but also has an interlayer adhesion with the polyester resin layer while improving the smoothness of the release coat surface. need to improve performance.

To address this problem, Patent Document 1 and Patent Document 2, for example, disclose techniques for controlling surface roughness by reducing particles contained in a release function coat layer provided on a polyester film.

JP 2016-210041 A Japanese Patent Application Laid-Open No. 2020-175668

However, although smoothing progresses to some extent by the methods described in Patent Documents 1 and 2, it is insufficient for next-generation applications, and the interlayer adhesion between the polyester film and the release coat layer Gender compatibility cannot be achieved.

The present invention controls the surface roughness and the number of protrusions with a height of 50 nm or more within a specific range, and provides a release functional layer with a water contact angle controlled within a specific range on a polyester film with good adhesion. It is an object of the present invention to provide a laminated polyester film having excellent releasability from a material, high smoothness, and excellent interlayer adhesion.

In order to solve the above problems, the present invention has the following configurations. i.e.
[I] A laminated polyester film having a polyester film and a release resin layer (P1), wherein the release resin layer (P1) is on at least one surface layer of the polyester film, and the following (1) to (3) A laminated polyester film that meets the requirements of
(1) When the surface of the release resin layer (P1) is the A surface and the arithmetic mean surface roughness of the A surface is SaA (nm), SaA is 0.5 or more and 4.5 or less. .
(2) _N50nmA is 200 or less, where protrusions are present on the A surface and the number of protrusions having a height of 50nm or more is _N50nmA (pieces/ ^mm2 ).
(3) CaA is 90 or more and 120 or less, where CaA (°) is the water contact angle of the surface A;
[II] When the film thickness is measured in the film width direction (the same direction as the film roll width direction), and the maximum value of the film thickness is D _MAX (μm) and the minimum value is D _MIN (μm), the following formula The laminated polyester film according to [I], wherein the thickness unevenness ΔD (μm) represented by (1) is 1.5 or less.
ΔD=D _MAX -D _MIN Expression (1)
[III] CaAP (°) is 87° or more, where _CaAP (°) is the water contact angle of the A-side after performing Gakushin abrasion treatment five times on the A-side [I ] or the laminated polyester film as described in [II].
[IV] The laminated polyester film according to any one of [I] to [III], wherein FA is 0.02 or more and 2.0 or less when the tape peeling force of the A side is FA (N/19 mm). .
[V] The laminated polyester film according to any one of [I] to [IV], wherein SpA is 25 or more and 100 or less, where SpA (nm) is the maximum protrusion height on the A side.
[VI] When the film surface opposite to the A side is B side and the arithmetic average surface roughness of B side is SaB (nm), SaB is 3 or more and 30 or less [I] to [V ] The laminated polyester film according to any one of the above.
[VII] The laminated polyester film according to any one of [I] to [VI], wherein D _P1 is 20 or more and 100 or less, where D _P1 (nm) is the thickness of the release resin layer (P1).
[VIII] The laminated polyester film according to any one of [I] to [VII], wherein the P1 layer contains no particles.
[IX] The laminated polyester film according to any one of [I] to [VIII], wherein the P1 layer is provided by an in-line coating method.
[X] The laminated polyester film according to any one of [I] to [IX], wherein the P2 layer does not contain particles when the polyester resin layer in contact with the P1 layer is the P2 layer.
[XI] The laminated polyester film according to any one of [I] to [X], which is used as a process film for manufacturing electronic parts.
[XII] The laminated polyester film according to any one of [I] to [XI], which is used as a release process film for an interlayer insulating film in the process of manufacturing a wiring board.
[XII] The polyester film according to any one of [I] to [XI], which is used as a support film for green sheet molding in the process of manufacturing a multilayer ceramic capacitor.

The laminated polyester film of the present invention has good surface smoothness, releasability and interlayer adhesion, and is used as a release process film for an interlayer insulating film in a process film for manufacturing electronic components and a process for manufacturing a wiring board. And it is particularly useful as a support film for green sheet molding in the process of manufacturing laminated ceramic capacitors.

FIG. 2 is a conceptual diagram showing R _{50 nm} measured with a scanning white light interference microscope. 3-layer configuration diagram of the laminated polyester film of the present invention 4-layer configuration diagram of the laminated polyester film of the present invention

The present invention will be described in detail below.

The present invention relates to laminated polyester films.

The laminated polyester film of the present invention must have a release resin layer on at least one surface layer of the polyester film and satisfy the following requirements (1) to (3). (Hereinafter, the surface of the release resin layer (P1) that satisfies the above requirements (1) to (3) may be referred to as the surface.)
(1) When the surface of the release resin layer (P1) is the A surface and the arithmetic mean surface roughness of the A surface is SaA (nm), SaA is 0.5 or more and 4.5 or less. .
(2) _N50nmA is 200 or less, where protrusions are present on the A surface and the number of protrusions having a height of 50nm or more is _N50nmA (pieces/ ^mm2 ).
(3) CaA is 90 or more and 120 or less, where CaA (°) is the water contact angle of the surface A;

The arithmetic mean surface roughness of the A side and the number of protrusions N _{50 nm} A (number/mm ² ) having a height of 50 nm or more are measured by scanning white light interference microscope (VertScan) according to the method described later. A water contact angle is measured using a surface contact angle meter described later.
The polyester film in the laminated polyester film of the present invention refers to a portion mainly composed of a polyester resin and laminated by a coextrusion method or the like described later, and the polyester film in the present invention is not limited to these, but specifically is, for example, a portion (P2 layer/P4 layer/P3 layer) consisting of a layer (P2) in contact with the release resin layer, an intermediate layer (P4), and a layer (P3) having a surface opposite to the surface. be. The release resin layer (P1) is a layer that is laminated on the P2 layer side of the polyester film using a coating composition described below. In addition, the layer (P3) having the surface opposite to the surface may be provided by a method such as in-line coating. In this case, the polyester film is a portion consisting of the P2 layer / P4 layer, and the release resin layer (P1) and the release resin layer (P1) is a layer laminated on the polyester film. The detailed structure of the laminated film and the lamination method will be described later.

(Release resin layer: P1 layer)
The arithmetic mean surface roughness SaA (nm) of the surface in the present invention is 0.5 or more and 4.5 or less, and when the laminated polyester film of the present invention is used as a process film for manufacturing electronic parts, the surface and It is a value that reflects the surface roughness of the mating member in contact, and affects the number of surface defects on the mating member that occur in the process after the laminated polyester film is peeled off. The arithmetic mean surface roughness (Sa) in the present invention is a value measured by the measurement method described below based on ISO 25178 determined by software attached to a scanning white light interference microscope. When the surface roughness SaA (nm) is 4.5 or less, surface defects in the mating member, such as distortion of the copper foil plate for wiring formed on the interlayer insulating film in the manufacturing process of the interlayer insulating film. Wiring transmission In the green sheet formation process in the production of multilayer ceramic capacitors, it is possible to reduce the loss and the decrease in electrostatic capacity due to the deterioration in the smoothness of thin-film green sheets. In addition, by setting the surface roughness SaA (nm) to 0.5 or more, it is possible to reduce the friction with the transport roll when the laminated film is transported in the processing step, and the surface scratches such as the transport roll can be reduced. The occurrence can be suppressed. A more preferable range of the surface roughness SaA (nm) is from 0.5 to 4.0, more preferably from 0.5 to 3.5.

In the present invention, the number of projections _N50nmA (number/ ^mm2 ) having a height of 50 nm or more on the surface must be 200 or less, and the laminated polyester film of the present invention was used as a process film for manufacturing electronic parts. It reflects the number of protrusions that transfer the coarse unevenness formation to the mating member in the case. The number of projections corresponding to each height in the present invention is a value measured by a measurement method described below based on ISO 25178 determined by software attached to a scanning white light interference microscope. By setting the number of protrusions N _50nm A (pieces/mm ² ) having a height of 50 nm or more to 200 or less, local damage to the mating member can be suppressed. It is possible to suppress the sheet crack defect when laminating the green sheets. A more preferable range for the number of projections N _50nm A having a height of 50 nm or more is 150 or less.

When SpA (nm) is the maximum projection height on the surface in the present invention, SpA (nm) is preferably 25 or more and 100 or less, reflecting the height of coarse projections on the surface. SpA (nm), which is the maximum protrusion height of the surface in the present invention, is a value measured by the measurement method described below based on ISO 25178, which is determined by software attached to a scanning white light interference microscope. By setting the maximum protrusion height SpA (nm) on the surface to 100 or less, and controlling the number of protrusions having a height of 50 nm or more N _{50 nm} A, it is possible to further suppress damage to the mating member. By setting the maximum protrusion height SpA (nm) on the surface to 25 or more, it is possible to suppress the occurrence of wrinkles due to the impermeability of the trapped air during film roll winding. A more preferable range of the maximum protrusion height SpA (nm) on the surface is 25 or more and 80 or less.

The water contact angle CaA (°) of the surface obtained by the measuring method described later in the present invention must be 90 or more and 120 or less, and when the laminated polyester film of the present invention is used as a process film for electronic component production. It is a value that contributes to the peelability from the mating member. By setting the water contact angle CaA (°) to 95 or more, the mating member provided on the A surface can be peeled off with a smaller force, and the mating member is not deformed and damaged by excessive force when peeled. can be suppressed. Further, by setting the water contact angle CaA (°) to 120 or less, it is possible to suppress repelling during coating and floating of the formed layer in the step of providing the mating member on the A surface. A more preferable range of the water contact angle CaA (°) is 95 or more and 115 or less, and a further preferable range is 95 or more and 110 or less.

<Constituents of P1 layer>
The configuration of the release resin layer (P1 layer) in the laminated polyester film of the present invention includes a release agent (A), an epoxy resin, a melamine resin, an oxazoline compound, a carbodiimide compound, a polyester resin, an acrylic resin, a urethane resin, and a silicone. It is preferably formed from a coating composition containing at least one resin or compound (B) selected from resins. With such a configuration, the water contact angle CaA (°) of the surface can be controlled to 90 or more and 120 or less, and the mating member can be formed and peeled off satisfactorily.

In addition, when the laminated polyester film of the present invention is used as a process film for manufacturing electronic parts, troubles such as poor conductivity, poor insulation, and pinhole defects due to the migration of silicone compounds (especially polydimethylsiloxane) to the product side may occur. From the viewpoint of prevention, it is preferable that the constituent components of the P1 layer do not contain a silicone compound.

Regarding the amount of silicone compound contained in the P1 layer, the details of the measurement method will be described later. It can be calculated by the ratio (P/K) [−] of the peak intensity (P) of the fragment derived from polydimethylsiloxane to K). The preferred range of P/K[-] is preferably less than 0.01.

When the laminated polyester film of the present invention is used as a process film for manufacturing electronic parts, FA is 0.02 or more, where FA (N/19 mm) is the tape peeling force of the surface obtained by the measurement method described later. It is preferably 0.0 or less. By setting the FA (N/19 mm) to 2.0 or less, it can be used as a release process film for an interlayer insulating film in the process of manufacturing a mating member, especially a wiring board, when used in a process film for electronic component manufacturing. Hydrophilic resin layers such as epoxy resin that become interlayer insulating films when used, and thin film ceramics such as barium titanate when used as a support film for green sheet molding in the process of manufacturing laminated ceramic capacitors. By setting FA (N/19 mm) to 0.02 or more, it is possible to prevent the mating member from inadvertently floating from the surface during process transportation. A more preferable range of the surface tape peeling force FA (N/19 mm) is 0.02 or more and 1.2 or less.

The surface of the laminated polyester film of the present invention preferably has a water contact angle CaA _P (°) of 87° or more after the Gakushin abrasion treatment described later is performed five times. The water contact angle CaA _{P (} °) reflects the adhesion between the release resin layer and the polyester film. This indicates that the release resin layer remains and the releasability can be maintained even after the parts have been transported in the manufacturing process.

<Release agent (A)>
The release agent (A) as used in the present invention means a compound that imparts release properties to the surface of the coating layer by being contained in the coating composition. Examples of the release agent (A) that can be used in the present invention include long-chain alkyl group-containing resins, olefin resins, fluorine compounds, and wax compounds. Among them, long-chain alkyl group-containing resins are preferable because they can impart good releasability.

Commercially available long-chain alkyl group-containing compounds may be used. Specifically, long-chain alkyl-based compounds "Ashioresin" (registered trademark) series manufactured by Asio Sangyo Co., Ltd., Lion Specialty Chemicals "Pyroyl" series of long-chain alkyl compounds manufactured by Co., Ltd., and "Resem" series of aqueous dispersions of long-chain alkyl compounds manufactured by Chukyo Yushi Co., Ltd. can be used. The releasing agent (A) preferably has an alkyl group with 12 or more carbon atoms, and more preferably has an alkyl group with 16 or more carbon atoms. By setting the number of carbon atoms in the alkyl group to 12 or more, the hydrophobicity is increased, and sufficient release performance as the release agent (A) can be exhibited. If the number of carbon atoms in the alkyl group is less than 12, the release performance may be insufficient. Although the upper limit of the carbon number of the alkyl group is not particularly limited, it is preferably 25 or less because production is easy.

The resin having an alkyl group having 12 or more carbon atoms is more preferably a resin having a side chain of an alkyl group having 12 or more carbon atoms on a polymethylene main chain. Since the main chain is polymethylene, the number of hydrophilic groups in the entire resin is reduced, so that the release effect of the release agent (A) can be further enhanced.

Regarding the presence or absence of the alkyl group having 12 carbon atoms, it corresponds to the alkyl group among the signals obtained from the laminated film, for example, by TOF-SIMS (TOF-SIMS: time-of-flight secondary ion mass spectrometry). It can be evaluated using the strength of the object. At this time, it is possible to perform continuous measurement in the depth direction by using a cutting method based on the ion sputtering method in combination, and it is also possible to evaluate the distribution state of the alkyl group-containing compound.

<Resin or compound (B)>
Examples of resins or compounds (B) that can be used in the P1 layer of the present invention include epoxy resins, melamine resins, oxazoline compounds, carbodiimide compounds, polyester resins, acrylic resins, urethane resins, and silicone resins. Among these resins, melamine resins and acrylic resins are preferable because the interaction between hydroxyl groups is easily controlled and the resin layer is easily changed by high-temperature heating.

Examples of epoxy resins that can be used as the resin or compound (B) include sorbitol polyglycidyl ether-based cross-linking agents, polyglycerol polyglycidyl ether-based cross-linking agents, diglycerol polyglycidyl ether-based cross-linking agents, and polyethylene glycol diglycidyl ether-based cross-linking agents. A cross-linking agent or the like can be used. As the epoxy resin, a commercially available one may be used. -521, EX-421, EX-313, EX-810, EX-830, EX-850, etc.), diepoxy-polyepoxy compounds manufactured by Sakamoto Pharmaceutical Co., Ltd. (SR-EG, SR-8EG, SR-GLG etc.), an epoxy cross-linking agent "EPICLON" (registered trademark) EM-85-75W manufactured by Dainippon Ink Mfg. .

The melamine resin that can be used as the resin or compound (B) includes, for example, melamine, methylolated melamine derivatives obtained by condensing melamine and formaldehyde, and partially or completely ethers obtained by reacting methylolated melamine with a lower alcohol. compounds, mixtures thereof, and the like can be used. The melamine resin may be either a condensate of a monomer or a polymer of dimers or higher, or a mixture thereof. Methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butanol, isobutanol and the like can be used as lower alcohols used for etherification. As the functional group, one having an imino group, a methylol group, or an alkoxymethyl group such as a methoxymethyl group or a butoxymethyl group in one molecule can be used as an imino group-type methylated melamine resin, a methylol group-type melamine resin, or a methylol group-type melamine resin. Examples include methylated melamine resins and fully alkyl-type methylated melamine resins. Among them, a methylolated melamine resin is most preferably used.

The oxazoline compound that can be used as the resin or compound (B) has an oxazoline group as a functional group in the compound, contains at least one monomer containing an oxazoline group, and has at least one It is preferably composed of an oxazoline group-containing copolymer obtained by copolymerizing other monomers.

Monomers containing an oxazoline group include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-Isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline and the like can be used, and a mixture of one or more of these can also be used. Among them, 2-isopropenyl-2-oxazoline is suitable because it is easily available industrially.

In the oxazoline compound, at least one other monomer used for the oxazoline group-containing monomer is a monomer copolymerizable with the oxazoline group-containing monomer, such as methyl acrylate, methyl methacrylate, Ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, acrylic acid esters such as 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, methacrylic acid esters, acrylic acid, methacrylic acid, itaconic acid, malein Unsaturated carboxylic acids such as acids, unsaturated nitriles such as acrylonitrile and methacrylonitrile, unsaturated amides such as acrylamide, methacrylamide, N-methylolacrylamide and N-methylolmethacrylamide, vinyl acetate and vinyl propionate Vinyl esters, vinyl ethers such as methyl vinyl ether and ethyl vinyl ether, olefins such as ethylene and propylene, halogen-containing α,β-unsaturated monomers such as vinyl chloride, vinylidene chloride and vinyl fluoride, styrene and α-methyl α,β-unsaturated aromatic monomers such as styrene can be used, and these can be used singly or as a mixture of two or more thereof.

In addition, the carbodiimide compound that can be used as the resin or compound (B) is a compound having one or more carbodiimide groups or cyanamide groups in a tautomeric relationship thereof as functional groups in the molecule. is. Specific examples of such carbodiimide compounds include dicyclohexylmethanecarbodiimide, dicyclohexylcarbodiimide, tetramethylxylylenecarbodiimide, urea-modified carbodiimide, and the like, and these can be used singly or in combination of two or more. .

The polyester resin that can be used as the resin or compound (B) has an ester bond in its main chain or side chain, and is preferably obtained by polycondensation from a dicarboxylic acid and a diol.

Aromatic, aliphatic, and alicyclic dicarboxylic acids can be used as the dicarboxylic acid that serves as a raw material for the polyester resin. Aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, orthophthalic acid, phthalic acid, 2,5-dimethylterephthalic acid, 1,4-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,2 -Bisphenoxyethane-pp'-dicarboxylic acid, phenylindanedicarboxylic acid and the like can be used. Aliphatic and alicyclic dicarboxylic acids include succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, dimer acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1, 4-Cyclohexanedicarboxylic acid and the like, and their ester-forming derivatives can be used.

Examples of diol components that are raw materials for the polyester resin include ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5- Pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 2,4-dimethyl-2-ethylhexane-1 , 3-diol, neopentyl glycol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethyl- 1,3-cyclobutanediol, 4,4'-thiodiphenol, bisphenol A, 4,4'-methylenediphenol, 4,4'-(2-norbornylidene)diphenol, 4,4'-dihydroxybiphenol, o -, m-, and p-dihydroxybenzene, 4,4'-isopropylidenephenol, 4,4'-isopropylidenebinediol, cyclopentane-1,2-diol, cyclohexane-1,2'-diol, cyclohexane- 1,2-diol, cyclohexane-1,4-diol and the like can be used.

As the polyester resin, modified polyester copolymers such as block copolymers and graft copolymers modified with acrylic, urethane, epoxy, etc. can be used.

The acrylic resin that can be used as the resin or compound (B) is not particularly limited, but those composed of alkyl methacrylate and/or alkyl acrylate are preferable.

Alkyl methacrylates and/or alkyl acrylates include methacrylic acid, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, and 2-hydroxy methacrylate. Ethyl, hydroxypropyl methacrylate, acrylic acid, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-hexyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, acrylic acid 2-Hydroxyethyl, hydroxypropyl acrylate, maleic acid, itaconic acid, acrylamide, N-methylol acrylamide, diacetone acrylamide and the like are preferably used. These can be used alone or in combination of two or more.

The urethane resin that can be used as the resin or compound (B) is a resin obtained by reacting a polyhydroxy compound and a polyisocyanate compound by a known urethane resin polymerization method such as emulsion polymerization or suspension polymerization. is preferred.

Examples of polyhydroxy compounds include polyethylene glycol, polypropylene glycol, polyethylene/propylene glycol, polytetramethylene glycol, hexamethylene glycol, tetramethylene glycol, 1,5-pentanediol, diethylene glycol, triethylene glycol, polycaptolactone, polyhexa Examples include methylene adipate, polyhexamethylene sebacate, polytetramethylene adipate, polytetramethylene sebacate, trimethylolpropane, trimethylolethane, pentaerythritol, polycarbonate diol, glycerin and the like.

Examples of polyisocyanate compounds that can be used include hexamethylene diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, isophorone diisocyanate, adducts of tolylene diisocyanate and trimethylenepropane, and adducts of hexamethylene diisocyanate and trimethylolethane.

The silicone resin that can be used as the resin or compound (B) may be a type containing a curable silicone resin as a main component, or a type containing a modified silicone resin as a main component. Any curing reaction type such as addition type, condensation type, ultraviolet curing type, electron beam curing type, non-solvent type, heat and ultraviolet curing combination type, etc. can be used as the type of curable silicone resin. The modified silicone resin may be a modified silicone resin obtained by graft polymerization with an organic resin such as an epoxy resin, a urethane resin, an alkyl resin, or the like. etc., it is preferable to use a modified silicone resin using a resin having a highly water-soluble functional group such as a hydroxyl group or a carboxyl group.

Furthermore, the release resin layer of the laminated polyester film of the present invention may contain an isocyanate compound as the resin or compound (B). Isocyanate compounds include, for example, tolylene diisocyanate, diphenylmethane-4,4′-diisocyanate, meta-xylylene diisocyanate, hexamethylene-1,6-diisocyanate, 1,6-diisocyanatohexane, and an adduct of tolylene diisocyanate and hexanetriol. , an adduct of tolylene diisocyanate and trimethylolpropane, polyol-modified diphenylmethane-4,4′-diisocyanate, carbodiimide-modified diphenylmethane-4,4′-diisocyanate, isophorone diisocyanate, 1,5-naphthalene diisocyanate, 3,3′-bitrylene -4,4'diisocyanate, 3,3'dimethyldiphenylmethane-4,4'-diisocyanate, metaphenylene diisocyanate and the like.

Furthermore, since the isocyanate group readily reacts with water, a blocked isocyanate compound in which the isocyanate group is masked with a blocking agent or the like can be preferably used in terms of the pot life of the coating material. In this case, heat is applied in the drying process after applying the coating composition to the polyester film, so that the blocking agent is dissociated and the isocyanate groups are exposed, resulting in the progress of the cross-linking reaction.

In the coating composition forming the resin layer of the laminated film of the present invention, the mass ratio of the release agent (A) and the resin or compound (B) is preferably in the range of 10/90 to 70/30. It is more preferably in the range of 15/85 to 65/35. Within this range, the amount of the release agent (A) in the resin layer becomes sufficient, and the initial tape peeling force and the peeling force from the surface layer after low-temperature heating can be improved. At the same time, the amount of the resin or compound (B), which is easily changed by heating, is also sufficient, so that the release property before and after heating can be improved.

The release resin layer (P1) of ^the present invention does not contain _particles . It is preferable from the viewpoint of control.

When the thickness of the P1 layer in the present invention is D _P1 (nm), D _P1 is preferably 20 or more and 100 or less. By setting the D _P1 (nm) to 20 or more, it is possible to exhibit a peeling function against the mating member, and by setting it to 100 or less, uneven drying of the coating composition is reduced, and only a local release resin layer It is possible to suppress the occurrence of unevenness.

The method of forming the P1 layer in the present invention is not particularly limited, but when using the coating composition, an off-coat method of coating after polyester film production or coating and drying during the polyester film production process. It is preferable to use either of the in-line coating methods performed, and the in-line coating method is preferable in order to maximize the effect of improving adhesion due to the surface treatment to the polyester film described later. Especially in the biaxially stretched polyester film manufacturing process, in-line coating is applied to the surface-treated polyester film after longitudinal stretching, and then the coating composition is dried in the transverse stretching process. Forming the release resin layer (P1) by stretching uniformly is most preferable from the viewpoint of making the surface smoother.

(Mating member provided on the surface)
<Hydrophilic resin layer>
When the laminated polyester film of the present invention is used as a release process film for an interlayer insulating film in the process of manufacturing a wiring board, a hydrophilic resin layer such as epoxy resin is provided on the surface of the release resin layer (P1). is preferably provided.

<Ceramic slurry>
When the laminated polyester film of the present invention is used as a support film for forming a green sheet in the process of manufacturing a laminated ceramic capacitor, the surface of the release resin layer (P1) is coated with a green sheet ceramic slurry. is preferred.

There are no particular restrictions on the raw material of the ceramic that constitutes the ceramic slurry, and various dielectric materials can be used. For example, oxides of metals such as titanium, aluminum, barium, lead, zirconium, silicon, yttrium, barium titanate, Pb(Mg _1/3 , Nb _2/3 )O ₃ , Pb(Sm _1/2 , Nb _1/2 )O ₃ , Pb(Zn _1/3 , Nb _2/3 )O ₃ , PbThO ₃ , PbZrO ₃ and the like can be used. These may be used singly or in combination of two or more.

Polymers such as polyurethane resins, urea resins, melamine resins, epoxy resins, vinyl acetate resins, acrylic resins, polyvinyl alcohol, polyvinyl butyral, and the like can be used as binder resins constituting the ceramic slurry. These may be used singly or in combination of two or more.

The solvent for the ceramic slurry may be either water or an organic solvent. In the case of organic solvents, toluene, ethanol, methyl ethyl ketone, isopropyl alcohol, γ-butyl lactone and the like can be used. These may be used singly or in combination of two or more. Moreover, a plasticizer, a dispersant, an antistatic agent, a surfactant, and the like may be added to the ceramic slurry, if necessary.

(Layer in contact with release resin layer (P1): P2 layer)
Regarding the P2 layer illustrated in FIGS. 2 and 3, the P2 layer in contact with the release resin layer (P1 layer) in the laminated polyester film of the present invention preferably contains polyester resin as a main component.

(polyester resin)
The polyester film referred to in the present invention indicates a film containing a polyester resin as a main component. The term "main component" as used herein refers to a component contained in an amount exceeding 50% by mass in 100% by mass of the total components of the film.

The polyester resin referred to in the present invention is obtained by polycondensation of 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.

Polyester resins used in the present invention include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene-2,6-naphthalenedicarboxylate (PEN), and dicarboxylic acid of PET from the viewpoint of mechanical properties and transparency. A copolymer obtained by copolymerizing isophthalic acid or naphthalene dicarboxylic acid as a part of the acid component, and a polyester obtained by copolymerizing cyclohexanedimethanol, spiroglycol, or diethylene glycol as a part of the diol component of PET are preferably used. is preferred.

When the surface to be the interface with the P1 layer of the P2 layer, which is the polyester resin layer in contact with the release resin layer (P1 layer) in the laminated polyester film of the present invention, is the C surface, the C surface is the interlayer before providing the P1 layer. It is preferable to apply a surface treatment for the purpose of improving adhesion and smoothness of the surface.

Examples of the surface treatment include corona treatment and atmospheric pressure plasma treatment from the viewpoint of improving the surface free energy of the polyester resin, and a method of preliminarily incorporating an additive component reactive with the P1 layer into the P2 layer. From the viewpoint of imparting uniform interlayer adhesion in the plane, it is preferable to perform plasma surface treatment by corona treatment or atmospheric pressure glow discharge, and the surface treatment suppresses the excessive deterioration of the polyester resin on the C plane and the generation of foreign matter. From the point of view, it is more preferable to use plasma surface treatment by atmospheric pressure glow discharge. Plasma surface treatment by atmospheric pressure glow discharge may be applied to the unstretched film after extrusion or to the stretched film in the polyester film manufacturing process. When forming a plasma surface treatment by atmospheric pressure glow discharge in the state of the unstretched film, the surface roughness SaA of the surface and the number of protrusions having a height of 50 nm or more N _{50 nm} A are controlled within a preferable range. and the most preferable from the viewpoint of improving interlayer adhesion.

When forming the P1 layer using an in-line coating method, by using a method of applying plasma surface treatment by atmospheric pressure glow discharge to the unstretched sheet state, adhesion with the coating composition constituting the release resin layer is improved. Along with improving for the following two reasons, the surface roughness of the release resin layer can be reduced by spreading the coating composition following the polyester film having the P2 layer as the outermost layer in the subsequent stretching step. . One of the reasons for the improvement in adhesion is that hydrophilic functional groups are added to the film surface by plasma surface treatment using atmospheric pressure glow discharge, thereby increasing affinity with the coating composition that constitutes the release resin layer. to be possible. The other is that the plasma surface treatment by atmospheric pressure glow discharge increases the surface roughness of the unstretched film surface and increases the contact area with the coating composition forming the release layer. This is because the amorphous polyester portion is scraped off by the plasma surface treatment by atmospheric pressure glow discharge, and the crystalline polyester portion remaining on the surface grows as projections in the subsequent stretching step, forming fine protrusions on the surface.

The atmospheric pressure here is in the range of 700 Torr to 780 Torr. In the atmospheric pressure glow discharge treatment, the film to be treated is guided between the facing electrodes and the earth roll, a plasma-exciting gas is introduced into the apparatus, and a high-frequency voltage is applied between the electrodes to excite the gas into plasma. Glow discharge is performed between electrodes. As a result, the film surface is finely processed (ashed) to form projections.

A plasma-excitable gas is a gas that can be plasma-excited under the conditions described above. Examples of plasma-exciting gases include rare gases such as argon, helium, neon, krypton and xenon, nitrogen, carbon dioxide, oxygen, fluorocarbons such as tetrafluoromethane, and mixtures thereof. Moreover, one type of plasma-excitable gas may be used alone, or two or more types may be combined at an arbitrary mixing ratio. It preferably contains oxygen in addition to at least one of argon, oxygen, and carbon dioxide, from the viewpoint of increasing activity when excited by plasma. In addition, by using a plasma-exciting gas with high activity, the amount of hydrophilic functional groups added to the film surface is increased, so that the adhesion is further improved and the arithmetic average surface roughness SaA (nm) of the surface is reduced. may decrease.

The frequency of the high frequency voltage in plasma processing is preferably in the range of 1 kHz to 100 kHz. In addition, the discharge treatment intensity (E value) obtained by the following method is preferably in the range of 10 to 2000 W min/m ² from the viewpoint of forming protrusions, more preferably 50 to 1000 W min/m ² . is. By increasing the discharge treatment strength (E value) to 10 W min / m ² or more, the effect of improving the adhesion between the film and the coating composition constituting the release resin layer can be obtained, and the discharge treatment strength (E value ) is suppressed to 2000 W·min/m ² or less, it is possible to suppress the formation of surface foreign substances having a height of 50 nm or more resulting from excessive damage to the polyester film surface.
<How to obtain the discharge treatment intensity (E value)>
E=Vp×Ip/(S×Wt)
E: E value (W min/m ² )
Vp: applied voltage (V)
Ip: applied current (A)
S: processing speed (m/min)
Wt: processing width (m)

In general, when the surface of a polyester film, especially a PET or PEN film having an amorphous portion and a crystal portion, is ashed by atmospheric pressure glow discharge treatment, the soft amorphous portion is ashed first. By subdividing the crystalline part and the amorphous part, finer protrusions can be formed by atmospheric pressure glow discharge treatment, and by increasing the crystalline part, the soft amorphous part can be deeply shaved. , it is possible to increase the height of the projections formed after the stretching process.

The P2 layer of the polyester film of the present invention contains particles, heat stabilizers, oxidation stabilizers, antistatic agents, organic / inorganic lubricants, nucleating agents, dyes, as long as the effects of the present invention are not impaired. , a dispersant, a coupling agent, and a wavelength conversion material.

In addition, the P1 layer of the polyester film of the present invention contains particles for the purpose of controlling the arithmetic mean surface roughness SaA (nm) of the surface and the number of protrusions having a height of 50 nm or more N _{50 nm} A (pieces/mm ² ) Although it may contain, it is a more preferable form not to contain particles. Particles to be added are not particularly limited, and either inorganic particles or organic particles may be used, and two or more types of particles may be used in combination. Examples of inorganic particles include calcium carbonate, magnesium carbonate, zinc carbonate, titanium oxide, zinc oxide, cerium oxide, magnesium oxide, barium sulfate, zinc sulfide, calcium phosphate, alumina (α-alumina, β-alumina, γ-alumina, δ-alumina), Mica, mica, titanium mica, zeolite, talc, clay, kaolin, lithium fluoride, calcium fluoride, montmorillonite, zirconia, wet silica, dry silica, colloidal silica, and the like. Examples of the organic particles include organic particles and core-shell type organic particles having acrylic resins, styrene resins, silicone resins, polyimide resins, and the like as constituent components.

The average particle diameter of the particles is preferably 10 nm or more and 100 nm or less in order to prevent an excessive increase in the number of projections of 50 nm or more on the surface.

The amount of particles contained in the P2 layer of the present invention is not particularly limited. preferably. It is more preferably 0.5% by mass or less, still more preferably 0.2% by mass or less.

(Layer having a surface opposite to the surface: P3 layer)
When the surface opposite to the surface in the laminated polyester film of the present invention is the B surface, and the resin layer constituting the B surface is the P3 layer, the arithmetic average surface roughness SaB (nm) of the B surface is 3 or more and 30 or less. is preferred. By setting SaB (nm) to 3 or more, it is possible to suppress the occurrence of wrinkles caused by entrapment of air during roll winding. can prevent excessive slippage and winding misalignment from occurring.

It is preferable to use a polyester resin, an acrylic resin, an epoxy resin, a melamine resin, a urethane resin, or a silicone resin as the main component of the P3 layer in the laminated polyester film of the present invention.

The particles contained in the P3 layer of the present invention preferably have an average particle diameter of 100 nm or more and 900 nm or less, which is determined by the method described below.

As for the average particle size of the particles (which will be described later in the description of the measuring method), it is preferable that two or more types of particles having different average particle sizes are contained. By containing particles with different average particle sizes and forming a surface having many protrusions with different heights, the contact area between films can be efficiently reduced and air entrainment during winding can be suppressed. may be possible. As a preferred combination of average particle sizes, when volume-based particle size distribution measurement is performed on the added particles and the particle size is plotted on the horizontal axis and the abundance ratio of the particles is plotted on the vertical axis, the particle size is 30 nm or more and less than 1200 nm. It preferably has a peak, and more preferably has one or more peaks in the particle size range of 30 nm or more and less than 350 nm and in the particle size range of 350 nm or more and less than 1200 nm. SaB can be within a preferable range even when the peak is in the region where the average particle size of the particles contained decreases as the thickness of the P3 layer decreases.

The particles contained in the P3 layer of the laminated polyester film of the present invention are not limited similarly to the P2 layer, and either inorganic particles or organic particles may be used. Examples of inorganic particles include calcium carbonate, magnesium carbonate, zinc carbonate, titanium oxide, zinc oxide, cerium oxide, magnesium oxide, barium sulfate, zinc sulfide, calcium phosphate, alumina (α-alumina, β-alumina, γ-alumina, δ-alumina), Mica, mica, titanium mica, zeolite, talc, clay, kaolin, lithium fluoride, calcium fluoride, montmorillonite, zirconia, wet silica, dry silica, colloidal silica, and the like. Examples of the organic particles include organic particles and core-shell type organic particles having acrylic resins, styrene resins, silicone resins, polyimide resins, and the like as constituent components.

The amount of particles added to the P3 layer of the laminated polyester film of the present invention is not limited at times, but from the viewpoint of controlling the arithmetic mean surface roughness SaB of the B side in a preferable range, the addition concentration is 3% by mass or less. is preferred. If the amount exceeds 3% by mass, the film may partially become cloudy even if particles having an average particle size within the preferred range are used, and the light transmittance and haze, which will be described later, may deviate from the preferred ranges. It is more preferably 2% by mass or less, still more preferably 1% by mass or less.

Regarding the method of providing the P3 layer in the laminated polyester film of the present invention, a method of extruding in a laminated state with the P2 layer (co-extrusion method) or a method of putting other resin layer raw materials into the film in the middle of film formation into an extruder and melt extruding. A method of laminating while extruding from a die (melt lamination method), a method of laminating films after film formation via an adhesive layer, and a coating composition containing a resin and particles as the main components like the P1 layer. The in-line coating method used can be used.

(Middle layer: P4 layer)
The laminated polyester film of the present invention may have a P4 layer between the P2 and P3 layers. If the purpose is to minimize the effect of the particles and additives contained in the P3 layer on the smoothness of the P2 and P1 layer surfaces (side A), the P4 layer is substantially free of particles and additives. preferably not included. On the other hand, when the purpose is to recover the laminated polyester film of the present invention again and use it as a recycled raw material, the influence on the smoothness of the P1 layer surface (A side) due to the generation of foreign matter derived from the recycled raw material is minimized. From the viewpoint of suppressing the thickness to 100%, it is preferable that the P4 layer contains the recycled raw material of the laminated polyester film of the present invention. The recycled raw material of the laminated polyester film is a recycled raw material composed of the entire laminated polyester film including up to the P1 layer, which is the release functional layer, but the P1 layer, P3 layer, etc. are removed from the laminated polyester film, and the polyester resin is the main component. A recycled raw material consisting only of a laminated portion may also be used. As a method for producing recycled raw materials, generally used methods can be used, for example, a method in which a laminated polyester film is pulverized once and then compacted into flakes, and a method in which the pulverized film is melted and extruded into chips.

(Laminated polyester film)
The polyester film in the laminated polyester film of the present invention is preferably biaxially oriented. The biaxial orientation improves the mechanical strength of the film, making it less prone to wrinkling and improving windability. can be uniform across the film. The term "biaxially oriented" as used herein refers to a pattern showing a biaxially oriented pattern in wide-angle X-ray diffraction. A polyester film can generally be obtained by stretching an unstretched thermoplastic resin sheet in the longitudinal direction and the width direction of the sheet, followed by heat treatment to complete crystal orientation. Details will be described later.

In the laminated polyester film of the present invention, the intrinsic viscosity (IV) of the polyester film is preferably 0.50 dl/g or more, more preferably 0.60 dl/g or more. IV is a number that reflects the length of the molecular chain, and the longer the molecular chain, the easier it is to clearly form a crystalline part and an amorphous part in the same molecular chain. This is preferable because it facilitates formation of finer protrusions. Further, when the IV is less than 0.50 dl/g, crystallization tends to proceed due to the short molecular chains, which may cause frequent breakage during the stretching process, making film formation difficult.

The laminated polyester film of the present invention consists of the above-described P1 layer, P2 layer, and P3 layer, and has a structure of three or more layers in which the surface and the opposite surface are arranged on the outermost surface (P1 layer/P2 layer/P3 layer, and P1 layer/P2 layer/P4 layer/P3 layer). In particular, when the laminated polyester film is recovered and used as a recycled raw material, a four-layer structure is preferred.

The method for laminating other resin layers such as the P1 layer and the P2 layer and the P3 layer is not particularly limited, but may be a co-extrusion method described later, or a method in which another resin layer raw material is put into an extruder during film formation. A method of laminating while extruding and extruding from a die (melt lamination method), a method of laminating films after film formation with an adhesive layer interposed, etc. can be used. Any coextrusion method that can be carried out is preferably used.

When the total layer thickness of the laminated polyester film of the present invention is D (μm), D is preferably 15 or more and 100 or less. By setting the total layer thickness D (μm) to 15 or more, film breakage due to stretching and heat treatment during the manufacturing process of the laminated polyester film and the processing process when used as a process film for electronic component manufacturing is suppressed. Also, by setting the total layer thickness D (μm) to 100 or less, it is possible to prevent the film rigidity of the laminated polyester film from being excessively increased, and to improve the workability in the heat lamination process in the manufacture of electronic parts. can. A more preferable range of the total layer thickness D (μm) is 20 or more and 50 or less.

When the thickness unevenness of the laminated polyester film of the present invention is ΔD (μm), ΔD is preferably 1.5 or less. The thickness unevenness ΔD is obtained by measuring the film thickness in the width direction of the film roll by the measurement method described later, and when the maximum value of the film thickness is D _MAX (μm) and the minimum value is D _MIN (μm), the following It is a value represented by Formula (1).
ΔD=D _MAX -D _MIN Expression (1)

By setting ΔD (μm) to be 1.5 or less, the surface shape of the surface is maintained over the entire film roll, so that the shape of the surface changes due to local unevenness in thickness, and the occurrence of surface defects in the mating member can be prevented. . Further, from the viewpoint of film winding properties, by setting ΔD (μm) to 1.5 or less, it is possible to suppress the occurrence of winding misalignment due to film thickness unevenness. A more preferable range of ΔD (μm) is 1.0 or less.

Methods for controlling ΔD (μm) within a preferable range include, for example, a method of making the slit width of a T-die uniform in the width direction when extruding a polyester film, and a method of stretching in the width direction using a tenter, which will be described later, in which the stretching temperature By reducing the unevenness in the width direction, the temperature applied to the laminated polyester film is made uniform in the width direction, thereby suppressing the occurrence of thickness unevenness due to poor stretching. Furthermore, when the release resin layer is provided by an in-line coating method, unevenness in thickness can be reduced by performing plasma surface treatment using atmospheric pressure glow discharge as described above. This is because the plasma surface treatment causes the coating composition to follow the polyester film with the P2 layer as the outermost layer and spread, so that the solvent in the coating composition evaporates uniformly in the width direction, and the temperature applied to the laminated polyester film becomes uniform. It is for the sake of becoming.

The laminated polyester film of the present invention preferably has a static friction coefficient (μs) of 0.3 or more and 1.0 or less on both sides of the film (the A side and the B side) from the viewpoint of film roll windability. By setting the static friction coefficient (μs) on both sides of the film to 0.3 or more, it is possible to suppress excessive slippage between the films during roll winding, and the static friction coefficient (μs) on both sides of the film is set to 1.0 or less. By doing so, it is possible to suppress the occurrence of wrinkles due to the adhesion of both sides of the film during roll winding.

(Method for producing laminated polyester film)
Next, the method for producing the laminated polyester film of the present invention will be described with an example in which a release resin layer is provided on the biaxially oriented polyester film by an in-line coating method. is not to be construed as being limited to

As a method for obtaining the polyester film used in the present invention, a conventional polymerization method can be employed. For example, a dicarboxylic acid component such as terephthalic acid or an ester-forming derivative thereof and a diol component such as ethylene glycol or an ester-forming derivative thereof are transesterified or esterified by a known method, followed by a melt polymerization reaction. You can get it by doing. Moreover, if necessary, the polyester obtained by the melt polymerization reaction may be subjected to a solid phase polymerization reaction at a temperature not higher than the melting point temperature of the polyester.

The polyester film of the present invention can be obtained by a conventionally known production method. Specifically, the polyester film of the present invention uses a method (melt casting method) in which a dried raw material is heated and melted in an extruder as necessary, and extruded from a nozzle onto a cooled cast drum to be processed into a sheet. be able to. As another method, the raw material is dissolved in a solvent, the solution is extruded from a die onto a support such as a cast drum or an endless belt to form a film, and then the solvent is removed from the film layer by drying to form a sheet. A method (solution casting method) or the like can also be used.

When producing a laminated polyester film of two or more layers by a melt casting method, an extruder is used for each layer constituting the laminated polyester film, the raw materials of each layer are melted, and these are combined into a confluence provided between the extrusion device and the nozzle. A method (co-extrusion method) is preferably used in which the layers are laminated in a molten state in an apparatus, then guided to a spinneret, extruded from the spinneret onto a cast drum, and processed into a sheet. An unstretched film is produced by statically contacting the laminated sheet on a cast drum cooled to a surface temperature of 20° C. or higher and 60° C. or lower and solidifying by cooling. By setting the surface temperature of the cast drum to 20°C or higher, the crystalline polyester portion on the surface of the unstretched film can be further increased, and the effect of forming fine projections after stretching by plasma surface treatment by atmospheric pressure glow discharge can be obtained. can be done. Further, by setting the surface temperature of the cast drum to 60° C. or less, the adhesion of the unstretched film to the cast drum can be suppressed, and an unstretched film with little thickness unevenness in the film running direction can be obtained. A more preferable range of the surface temperature of the cast drum is 25°C or higher and 55°C or lower.

Then, the unstretched film obtained here is subjected to surface treatment such as plasma surface treatment by atmospheric pressure glow discharge. These surface treatments may be performed immediately after obtaining an unstretched film or after stretching in the running direction of the film (hereinafter sometimes referred to as the longitudinal direction). It is preferable from the viewpoint of promoting the formation of protrusions. The surface to be surface-treated may be either the surface in contact with the cast drum (drum surface) or the surface not in contact with the cast drum (non-drum surface).

Next, the resulting unstretched film that has been plasma surface-treated by atmospheric pressure glow discharge is stretched in the longitudinal direction and in a direction perpendicular to the longitudinal direction (hereinafter sometimes referred to as the width direction) to biaxially align the film. A release resin layer is provided by applying the coating composition by an in-line coating method and drying the coating composition. As a stretching method, a simultaneous biaxial stretching method or a sequential biaxial stretching method can be used. When the simultaneous biaxial stretching method is used, the coating composition is applied to at least one side of an unstretched film, and the film is stretched and dried to provide a release resin layer. Further, when using a sequential biaxial stretching method in which stretching is first performed in the longitudinal direction and then in the width direction, after stretching in the longitudinal direction, the coating composition is applied to at least one side of the film and stretched in the width direction. A release resin layer is provided by performing drying at the same time. From the viewpoint of further improving the adhesion between the polyester film and the release resin layer, it is preferable to provide the release resin layer by an in-line coating method after the longitudinal stretching in the sequential biaxial stretching.

(sequential biaxial stretching)
The stretching conditions for biaxially stretching an unstretched film are not particularly limited. It is preferable that the film is guided to a group of rolls heated to the above, stretched in the longitudinal direction (longitudinal direction, that is, the traveling direction of the film), and cooled by a group of rolls set to a temperature of 20°C or higher and 50°C or lower. The lower limit of the temperature of the heating rolls in longitudinal stretching is not particularly limited as long as the stretchability of the sheet is not impaired, but it is preferably higher than the glass transition temperature of the polyester resin used. Moreover, the preferred range of the draw ratio in the longitudinal direction is 3 times or more and 5 times or less. A more preferable range is 3 times or more and 4 times or less. When the stretching ratio in the longitudinal direction is 3 times or more, oriented crystallization proceeds and the film strength can be improved. On the other hand, by setting the draw ratio to 5 times or less, it is possible to suppress excessive oriented crystallization of the polyester resin due to the drawing, making it brittle and causing breakage during film formation.

Regarding stretching in the direction perpendicular to the longitudinal direction (width direction), both ends of the film are held with clips and guided to a tenter, and in an atmosphere heated to a temperature of 70 ° C or higher and 160 ° C or lower, the film is stretched perpendicular to the longitudinal direction. It is preferable to stretch the film by 3 times or more and 5 times or less in the direction (width direction), and then heat-treat the stretched film to stabilize the internal orientation structure. Regarding the thermal history temperature of the film during the heat treatment, it should be confirmed by the minute endothermic peak (sometimes referred to as Tmeta) temperature appearing directly below the melting point temperature measured by a differential scanning calorimeter (DSC) described later. However, when polyester (melting point 255 ° C.) is the main component, the set temperature of the tenter device is preferably set so that the maximum temperature in the tenter is 200 ° C. or higher and 250 ° C. or lower. When a plastic resin is used as the main component, it is preferable to set the melting point of the resin to −55° C. or less and −5° C. or less. By setting the heat treatment temperature to 200° C. or higher, the dimensional stability of the laminated polyester film can be improved, and by setting the heat treatment temperature to 250° C. or lower, the occurrence of film breakage due to melting of the polyester film is suppressed, resulting in good productivity. can be manufactured. A more preferable range is 220° C. or higher and 245° C. or lower.

The range of Tmeta, which represents the thermal history temperature of the film during heat treatment, is preferably 190° C. or higher and 245° C. or lower for the reasons described above when the polyester resin is used as the main component. A more preferable range is 210° C. or higher and 240° C. or lower.

Furthermore, for the purpose of imparting dimensional stability after the heat treatment, a relaxation treatment may be performed within a range of 0% or more and 6% or less.

The draw ratio is 3 times or more and 5 times or less in each of the longitudinal direction and the width direction. It is more preferable to be 20 times or less. By setting the area magnification to 9 times or more, it is possible to promote the molecular orientation of the obtained laminated polyester film and improve durability, and by setting the area magnification to 22 times or less, it is possible to suppress the occurrence of tearing during stretching. can.

(inline coat)
In the present invention, it is preferable to apply the coating composition to at least one side of the polyester film and then dry it to form the release resin layer.

Any known coating method can be used as the coating method of the coating composition in the laminated polyester film of the present invention. Examples thereof include wire bar coating, reverse coating, gravure coating, die coating, blade coating, dip coating, air knife coating, curtain coating, and roller coating.

In the present invention, when the coating composition contains a solvent, it is preferable to use an aqueous solvent as the solvent. By using a water-based solvent, rapid evaporation of the solvent in the drying process can be suppressed, and not only can a uniform resin layer be formed, but it is also excellent in terms of environmental load.

Here, the aqueous solvent refers to water, or water and alcohols such as methanol, ethanol, isopropyl alcohol, and butanol, ketones such as acetone and methyl ethyl ketone, and glycols such as ethylene glycol, diethylene glycol, and propylene glycol that are soluble in water. refers to the one in which the organic solvent is mixed in an arbitrary ratio.

Furthermore, the solid content concentration of the coating composition is preferably 40% by mass or less. By setting the solid content concentration to 40% by mass or less, it is possible to impart good applicability to the coating composition and to produce a laminated film having a uniform resin layer.

In addition, the solid content concentration represents the ratio of the mass of the coating composition to the mass of the coating composition excluding the mass of the solvent (that is, [solid content concentration (mass%)] = [( (mass of coating composition)−(mass of solvent)]/[mass of coating composition]×100).

In the width direction stretching step of the laminated polyester film manufacturing process of the present invention, as described above, by stretching in a temperature range of 70 ° C. or higher and 160 ° C. or lower, the coating composition is dried to complete the removal of the solvent and the release resin layer. can be formed uniformly. Further, as described above, by performing heat treatment in the temperature range of 200° C. or higher and 250° C. or lower, the heat curing of the coating composition can be completed and the strength of the resin layer can be improved.

[Method for evaluating characteristics]
A. Evaluation by scanning white interference microscope (VertScan) A 6 cm × 6 cm sample was taken from the laminated polyester film, and each sample was subjected to a scanning white interference microscope (device: Hitachi High-Tech Science Co., Ltd. “VertScan” (registered trademark) VS1540). The surface of the laminated polyester film is measured using a 50x objective lens with a measurement area of 113 μm×113 μm for 30 fields of view. A sample set is measured by setting the sample on the stage so that the measurement Y-axis is in the longitudinal direction of the sample film (the direction in which the film is wound). In the case of a sample whose longitudinal direction is unknown, the Y-axis of the sample film is measured in any one direction, then rotated 120 degrees, and then measured 120 degrees. Measurements are taken in the rotated direction, and the average of the respective measurement results is taken as the number of projections of the sample. In addition, the sample film to be measured is sandwiched between two metal frames with rubber packing, and the sample surface is measured with the film in the frame in a stretched state (a state in which slack and curl are removed from the sample).

The obtained microscopic image was subjected to image processing under the following conditions using the surface analysis software VS-Viewer Version 10.0.3.0 built into the microscope, and the arithmetic mean surface roughness and each height Find the number of protrusions of
(Image processing conditions)
Image processing is performed in the following order.
・Interpolation processing: Complete interpolation ・Filter processing: Median (3 x 3 pixels)
・Surface correction: 4th order.

(i) Arithmetic mean surface roughness (SaA and SaB)
Scanning white interference microscope measurement of 30 fields of view is performed on the surface (A surface) of the laminated polyester film, and for each measurement image subjected to the above image processing, the following analysis conditions in the "ISO parameter" analysis in the surface analysis software The arithmetic mean surface roughness Sa (nm) obtained by selecting "Height Parameters" and outputting the obtained numerical value group in the parameter sheet column, and the average value of 30 fields of view is the arithmetic mean surface roughness of the measurement surface Let SaA (nm). Similarly, scanning white interference microscope measurement is performed on the surface opposite to the surface (B surface), and for each measurement image subjected to the image processing described above, the following analysis conditions in the "ISO parameter" analysis in the surface analysis software Select "Height Parameters" together with "Height Parameters" and output the obtained numerical value group to the parameter sheet column to obtain the arithmetic mean surface roughness Sa (nm), and from the average value of 30 fields of view, the surface opposite to the surface (B Arithmetic mean surface roughness SaB (nm) of surface) is obtained.
(ISO parameter analysis conditions)
ISO parameter analysis processing is performed under the following conditions.
・ S-Filter: Automatic/regular probability paper Number of divisions: 300
Upper limit of calculation range: 3.000
Lower limit of calculation range: -3.000
・Parameters: Select only "Height Parameters" ・Output: Select "Parameter List" (parameter sheet output)
By selecting "Height Parameters" in the "ISO Parameter" window displayed by the above ISO parameter analysis and performing "Add to Parameter Sheet", "Sa[ μm]” is converted into nm unit and used.

(ii) maximum protrusion height (SpA)
Microscopic image observation of the surface (A surface) is performed in the same manner as in (i) above, and for each measurement image subjected to the image processing described above, "Peak The maximum projection height Sp (nm) is obtained from the value obtained by converting [μm]” into nm units, and the average value of 30 fields of view is taken as the arithmetic mean surface roughness SpA (nm) of the surface (A surface).

(iii) Number of protrusions with a height of 50 nm or more (N _{50 nm} A)
After subjecting the surface (A surface) to microscopic image observation and image processing in the same manner as in (i) above, the surface analysis software VS-Viewer Version 10.0.3.0 built into the microscope was used to perform the following Particle analysis processing is performed under the conditions, and the number (pieces) of particles displayed on the "particle analysis" screen detected at a height threshold of 50 nm (R50 nm, height threshold setting value: 0.05 μm) is measured. By dividing by (113 μm×113 μm), the number of projections (pieces/mm ² ) with a height of 50 nm or more is obtained.
(Particle analysis conditions)
Projection analysis processing is performed under the following conditions.
・Analysis type: Rush analysis ・Image correction: None ・Processing
Height threshold: 0.05 μm
Particle shaping: None Reference height: Zero plane (average plane)
・Determination target height/depth: -10000 μm≦h≦10000 μm
Maximum diameter: -10000 μm≦d≦10000 μm
Volume: V≧0.0000 μm3
Aspect ratio: r≧0.0000
・Histogram: Number of divisions 50
The same operation is performed in all the measured 30 fields of view, and the average value is taken as the number of protrusions N _{50 nm} A (pieces/mm ² ) having a height of 50 nm or more on the sample.
(Reference height: Zero plane (average plane))
As the zero plane (average plane) in the reference height setting, the measurement image (113 μm × 113 μm) obtained by performing the microscope image observation by the above-mentioned method and performing the above-mentioned image processing is automatically calculated by the following formula. Use the plane of the average value (Ave) of the heights found in .

lx: range length in the X direction in each measurement image subjected to the image processing described above ly: range length in the Y direction in each measurement image subjected to the image processing described above h(x, y): Height at each image point (x, y) in the processed measurement image

B. Water contact angle (CaA)
After leaving the laminated polyester film of the present invention in an atmosphere of room temperature 23 ° C. and humidity 65% for 24 hours, using a contact angle meter CA-D type (manufactured by Kyowa Interface Science Co., Ltd.) under that atmosphere, based on JIS K6768. The contact angle of the surface (A surface) with respect to water is measured. The water contact angle CaA (°) of the surface A is defined as the average value of 3 measurements obtained by measuring 5 times and excluding the maximum and minimum values.

C. Water contact angle after Gakushin abrasion treatment (CaA _P )
(i) Gakushin Abrasion Treatment A rectangular sample is prepared by cutting a laminated polyester film into a width of 3 cm and a length of 15 cm. Gakushin type dyeing color fastness tester (manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.) so that the surface (A side) is the side that contacts the friction element and the movement direction of the friction element is the longitudinal direction of the sample. Paste the sample. A white cotton cloth impregnated with a 1:1 mixture of toluene and methyl ethyl ketone was attached to the friction element and reciprocated 5 times on the surface (A side) to prepare a sample after Gakushin abrasion treatment.

(ii) water contact angle ( _CaAP ) after Gakushin abrasion treatment
The above B. The water contact angle is measured on the surface of the sample prepared in (i) above and subjected to the Gakushin abrasion treatment in the same manner as in the section above. The water contact angle CaA _P (°) of the surface A after Gakushin abrasion treatment is taken as the average value of 3 measurements obtained by excluding the maximum and minimum values of the 5 measurements.

D. Film thickness (i) Total layer thickness The total layer thickness of the laminated polyester film is measured using a dial gauge, according to JIS K7130 (1992) A-2 method, with 10 films stacked at any 5 locations. was measured. The average value is divided by 10 to obtain the total thickness of the film (μm).

(ii) Laminate Thickness A cross section of the laminated polyester film is cut out with a microtome in a direction parallel to the width direction of the film. The cross section is observed with a scanning electron microscope at a magnification of 5,000 to 20,000 times to determine the thickness ratio of each laminated layer. The thickness of each layer is calculated from the obtained lamination ratio and the thickness of all the layers obtained in the above section (i).

(iii) Thickness (D _P1 ) of release resin layer (P1)
A laminated polyester film is dyed with ruthenium tetroxide ( _RuO4 ) and/or osmium tetroxide ( _OsO4 ). The laminated polyester film is frozen and cut in the thickness direction of the film to obtain 10 ultra-thin slice samples (10 pieces) for cross-sectional observation of the resin layer. A section of each sample is observed with a TEM (transmission electron microscope: H7100FA type manufactured by Hitachi, Ltd.) at a magnification of 10,000 to 1,000,000 to obtain a photograph of the section. The measured values of the thickness of the release resin layer (P1 layer) having the surface at 10 points (10 pieces) are averaged to obtain the thickness D _P1 (nm) of the release resin layer.

(iv) Width direction thickness unevenness ΔD of film roll
A continuous contact thickness gauge (KG601B manufactured by Anritsu Co., Ltd.) is used to measure the full width of the film roll of the laminated polyester film in the width direction.

In the obtained film thickness, the thickness unevenness ΔD (μm) is obtained by subtracting the minimum value (D _MIN ) from the maximum value (D _MAX ) according to the following formula (1). Measurement is performed three times every 15 m in the film unwinding direction, ΔD is obtained for each measurement, and the maximum value thereof is defined as the thickness unevenness ΔD (μm) of the laminated polyester film.
ΔD=D _MAX -D _MIN Expression (1)

The width direction of the film roll refers to a direction perpendicular to the film unwinding direction in the film plane of the laminated polyester film of the present invention. When the unwinding direction of a laminated polyester film cut into a specific size is unknown, the thickness unevenness is measured in two directions: a specific direction and a direction tilted 90° from the measurement direction in the film plane. , the maximum value of which is defined as the thickness unevenness ΔD of the laminated polyester film.

Similarly, if it is a laminated polyester film cut into a specific size and it is difficult to measure three times every 15 m in the unwinding direction, measure the thickness unevenness in the width direction at the trisecting point of the full width in the unwinding direction. and let the maximum value thereof be the thickness unevenness ΔD of the laminated polyester film.

E. Tape peel force (FA)
Tape peel force was measured as follows.
First, an acrylic polyester adhesive tape (manufactured by Nitto Denko Corporation, Nitto 31B tape, 19 mm width) is pasted on the release resin layer of the laminated polyester film of the present invention, and a 2 kgf roller is reciprocated once from above, Create a tape laminated laminated film. After that, the tape-laminated laminated film was allowed to stand in an environment of 25° C. and 65% RH for 24 hours, and then, using a universal testing machine “Autograph AG-1S” manufactured by Shimadzu Corporation, a peel angle of 180° and a tensile test were performed. The peel force (N/19 mm) is measured at a speed of 300 mm/min. From the peel force (N/19 mm)-test time (sec) graph obtained by measurement, the average value of the peel force at 5 to 10 sec is calculated. The same measurement is performed 5 times, and the average of the 3 times excluding the maximum and minimum values is taken as the peel force FA (N/19 mm) of the laminated film.

F. Static friction coefficient (μs)
After conditioning the humidity of the polyester film of the present invention at 23° C. and 65% RH, two strips with a width of 75 mm and a length of 100 mm were cut out so that the direction of the film production line was the longitudinal direction. (model ST-200, manufactured by Techno Needs Co., Ltd.) is used, and the measurement is performed in an atmosphere of 23° C. and 65% RH. A strip-shaped sample is set and fixed on the measuring sample stand of the apparatus so that the direction of pulling the strip sample becomes the longitudinal direction of the strip sample and the surface side faces upward. Another strip-shaped sample is placed on top of it so that the surface is up and the direction of pulling is the longitudinal direction, and the surface and the opposite surface are brought into contact, and the end of the sample is attached to the U for weight detection of the apparatus. fixed to the game. After that, the film was allowed to stand, and a sample contact surface was a Teflon (registered trademark) sheet with a size of 6.5 cm × 6.5 cm. Measure the static friction coefficient when pulled under the following conditions. The static friction coefficient (μs) is obtained by measuring 10 times and excluding the top two points and the bottom two points and excluding the average value of six measurements.
Measurement distance: 12mm
Measurement speed: 210 mm/min.

G. Polymer Properties (i) Intrinsic Viscosity (IV)
In 100 ml of ortho-chlorophenol, the measurement sample (polyester resin (raw material) or the P1 layer of the solar cell backside protection sheet is separated) is dissolved (solution concentration C (measurement sample weight/solution volume) = 1.2 g/ 100 ml), and the viscosity of the solution at 25° C. was measured using an Ostwald viscometer. Also, the viscosity of the solvent was measured in the same manner. Using the obtained solution viscosity and solvent viscosity, [η] was calculated by the following formula (2), and the obtained value was taken as the intrinsic viscosity (IV).
ηsp/C=[η]+K[η] ² ·C (2)
(Here, ηsp = (solution viscosity/solvent viscosity) - 1, K is the Huggins constant (assumed to be 0.343).)
When the solution in which the measurement sample was dissolved contained an insoluble matter such as inorganic particles, the following method was used for the measurement.
(1-1) Dissolve a measurement sample in 100 mL of ortho-chlorophenol to prepare a solution with a concentration higher than 1.2 g/100 mL. Here, the weight of the measurement sample subjected to ortho-chlorophenol is defined as the weight of the measurement sample.
(1-2) Next, the solution containing insoluble matter is filtered, and the weight of the insoluble matter and the volume of the filtrate after filtration are measured.
(1-3) Add ortho-chlorophenol to the filtrate after filtration, (measurement sample weight (g) - weight of insoluble matter (g)) / (volume of filtrate after filtration (mL) + added ortho-chlorophenol The volume (mL) of phenol is adjusted to 1.2 g/100 mL.
(For example, when a concentrated solution with a measurement sample weight of 2.0 g / solution volume of 100 mL was prepared, the weight of the insoluble matter when the solution was filtered was 0.2 g, and the volume of the filtrate after filtration was 99 mL. is adjusted by adding 51 mL of ortho-chlorophenol ((2.0 g - 0.2 g)/(99 mL + 51 mL) = 1.2 g/100 mL)).
(1-4) Using the solution obtained in (1-3), the viscosity at 25 ° C. was measured using an Ostwald viscometer, and using the obtained solution viscosity and solvent viscosity, the above formula (3 ) to calculate [η], and the obtained value is defined as the intrinsic viscosity (IV).

(ii) Terminal carboxyl group content (unit: eq/t, indicated as COOH content in the table)
It was measured by the method of Maulice. (Reference MJ Maulice, F. Huizinga, Anal. Chem. Acta, 22, 363 (1960)).

That is, 0.5 g of a measurement sample (polyester (raw material) or polyester film from which only the P1 layer is separated) is weighed with an accuracy within 0.001 g. 50 ml of a solvent obtained by mixing o-cresol/chloroform at a mass ratio of 7/3 is added to the sample, heated to an internal temperature of 90° C., and then heated and stirred for 20 minutes to dissolve the sample. Also, the mixed solvent alone is similarly heated separately as a blank solution. The solution is cooled to room temperature and titrated with a 1/50N potassium hydroxide methanol solution using a potentiometric titrator. Titration is also carried out in the same manner for a blank solution containing only the mixed solvent.

A value calculated by the following formula was defined as the terminal carboxyl group amount of the measurement sample.
Terminal carboxyl group amount (equivalent / t) = {(V1-V0) × N × f} × 1000 / S

Here, V1 is the titrant volume (mL) in the sample solution, V0 is the titrant volume (mL) in the blank solution, N is the titrant normality (N), f is the titrant factor, and S is the polyester composition. It is the mass (g) of the object.

H. Evaluation of Particles Contained (i) Average Particle Size Regarding the polyester film of the present invention, a small piece was cut in the direction perpendicular to the surface using a microtome, and the cross section was observed with a field emission scanning electron microscope JSM-6700F (JEOL ( Co., Ltd.) was used to observe and photograph the P1 layer or P2 layer at a magnification of 10000 times. The particle size distribution of particles present in the P1 layer or P2 layer was obtained from the cross-sectional photograph using image analysis software Image-Pro Plus (Nippon Roper Co., Ltd.). Cross-sectional photographs were selected from different arbitrary measurement fields, and the circle-equivalent diameters of 400 or more particles arbitrarily selected from the cross-sectional photographs were measured to obtain the volume-based average particle diameter. When two or more types of particles are contained in the constituent elemental analysis of the particles below, the equivalent circle diameters of 200 or more particles are measured for each particle, and the average particle diameter is obtained from the average value of the volume-based equivalent circle diameters. .

(ii) Particle size distribution analysis Volume-based particle size distribution analysis was performed on the particle diameters obtained by the method described in (i) above. Here, the particle diameters on the horizontal axis in the volume-based particle size distribution are expressed in classes at intervals of 10 nm with 0 nm as the starting point. From the particle size distribution chart of the obtained particles, the particle size of the peak top indicating the maximum was read.

(iii) Particle content The P1 layer or P2 layer portion of the polyester film of the present invention was put into 200 ml of a 1N-KOH methanol solution and heated under reflux to dissolve the polymer. 200 ml of water was added to the dissolved solution, the liquid was then centrifuged to settle the particles, and the supernatant was removed. Water was further added to the particles, washing and centrifugation were repeated twice. The particles thus obtained were dried and weighed to calculate the content (% by mass) of the particles contained in each layer. When organic particles are included in the added particles, select a solvent that dissolves the polymer but does not dissolve the organic particles, dissolves the polymer without heating to reflux, and centrifuges the particles to determine the particle content (% by mass). Calculated.

I. Method for analyzing the composition of the surface of the release resin layer Using GCIB-TOF-SIMS (GCIB: gas cluster ion beam, TOF-SIMS: time-of-flight secondary ion mass spectrometry) , the composition of the resin layer surface of the laminated film was analyzed. The measurement conditions were as follows.
<Sputtering conditions>
Ion source: Argon gas cluster ion beam <detection conditions>
Primary ion: Bi3++ (25 keV)
Secondary ion polarity: Negative
Mass range: m/z 0-1000
Measurement range: 200 x 200 µm2
The peak intensity of the fragment detected at the maximum intensity was K, the peak intensity of the fragment derived from polydimethylsiloxane (SiCH3 + fragment ion (M/Z = 43)) was P, and the ratio P/K was calculated. When P/K<0.01, it was determined that the resin layer did not substantially contain a silicone compound.

[Method for evaluating application characteristics]
J. Process Conveyability (i) Surface Scratches Defects The laminated polyester film of the present invention is formed at a film forming speed of 100 m/min or more, and a continuous film roll of 5000 m is collected ten times. Ten film rolls thus obtained were unwound and evaluated for surface scratches on the surface of the release resin layer (the surface described above) as follows.
A: Among 10 rolls, 2 or less rolls had surface scratches.
B: Out of 10 rolls, 3 or more and 4 or less rolls had surface scratches.
C: Out of 10 rolls, 5 or more and 6 or less rolls with surface scratches.
D: Out of 10 rolls, 7 or more rolls had surface scratches.
As for process transportability, A to C are good, and A is the best among them.

(ii) Peeling of Release Resin Layer Ten film rolls obtained in the above section (i) were unwound, and the occurrence of peeling of the release resin layer on the surface was evaluated as follows.
A: Of the 10 rolls, the number of rolls in which peeling of the release resin layer occurred was 0.
B: Among 10 rolls, 1 or more and 2 or less rolls had peeling of the release resin layer.
C: Out of 10 rolls, 3 or more and 4 or less rolls had peeling of the release resin layer.
D: 5 rolls or more out of 10 rolls had separation of the release resin layer.
As for peeling of the release resin layer, A to C are good, and A is the best among them.

K. Winding Misalignment The laminated polyester film of the present invention is formed at a film forming speed of 100 m/min or more, and 10 consecutive 5000 m rolls are taken. The 10 film rolls thus obtained were evaluated for occurrence of winding misalignment as follows.
A: Out of 10 rolls, the number of rolls in which winding misalignment occurred is 2 or less.
B: Out of 10 rolls, 3 or more and 4 or less rolls have misaligned rolls.
C: Out of 10 rolls, 5 or more and 6 or less rolls with misalignment.
D: Out of 10 rolls, 7 or more rolls were misaligned.
As for winding misalignment, A to C are good, and among them, A is the best.
As for process transportability, A to C are good, and A is the best among them.

L. Winding Misalignment The laminated polyester film of the present invention is formed at a film forming speed of 100 m/min or more, and 10 consecutive 5000 m rolls are taken. The occurrence of winding wrinkles on the ten film rolls thus obtained was evaluated as follows.
A: Among 10 rolls, 2 or less rolls have winding wrinkles.
B: Out of 10 rolls, 3 or more and 4 or less rolls had winding wrinkles.
C: Among 10 rolls, 5 or more and 6 or less rolls with winding wrinkles.
D: Among 10 rolls, 7 or more rolls had winding wrinkles.
A to C are good for winding wrinkles, and A is the best among them.

M. Evaluation of Coating and Peelability of Epoxy Resin Layer (i) Thermosetting Epoxy Resin Composition Liquid bisphenol A type epoxy resin (epoxy equivalent: 180, "Epikote 828EL" manufactured by Japan Epoxy Resin Co., Ltd.) and 28 parts of naphthalene type tetrafunctional 28 parts of an epoxy resin (epoxy equivalent: 163, "HP4700" manufactured by Dainippon Ink & Chemicals Co., Ltd.) is heated and dissolved in a mixed solvent of 15 parts of methyl ethyl ketone and 15 parts of cyclohexanone with stirring. 110 parts of a 50% solid content methyl ethyl ketone solution of a naphthol-based curing agent (“SN-485” manufactured by Tohto Kasei Co., Ltd.) and 0.1 part of a curing catalyst (“2E4MZ” manufactured by Shikoku Kasei Kogyo Co., Ltd.) , spherical silica (average particle size 0.5 μm, "SO-C2" manufactured by Admatechs) 70 parts, polyvinyl butyral resin solution (manufactured by Sekisui Chemical Co., Ltd. "KS-1" solid content 15% ethanol and toluene (1:1 solution) of (30 parts) are mixed and uniformly dispersed with a high-speed rotating mixer to prepare a thermosetting epoxy resin composition.

(ii) Formation of epoxy resin layer The thermosetting epoxy resin composition mixed with the above composition was applied onto the release resin layer of the laminated polyester film of the present invention using an applicator, and then heated at 100°C in a hot air oven. Dry for 5 minutes to form an epoxy resin laminated sheet.

(iii) Applicability of epoxy resin The epoxy resin having the composition shown in the above item (ii) was applied to three final thicknesses (40 μm, 10 μm, 1 μm) using an applicator. After coating the layer, it is dried in a hot air oven at 100° C. for 5 minutes to form an epoxy resin laminated film. The presence or absence of repelling of the epoxy resin-laminated polyester film was visually evaluated. In general, repelling tends to occur more easily as the coating thickness of the epoxy resin is reduced.
A: Repelling is not observed at any coating thickness.
B: Repelling is not observed at the coating thickness of 40 μm and 10 μm, but repelling is observed at the coating thickness of 1 μm.
C: Repelling is not observed with a coating thickness of 40 μm, but repelling is observed with a coating thickness of 10 μm and 1 μm.
D: Repelling is observed in all coating thicknesses.
As the coatability of the epoxy resin, A to C are good, and among them, A is the best.

(iv) Peeling force of the epoxy resin layer The epoxy resin mixed in the same manner as in (ii) was applied onto the release resin layer of the laminated polyester film of the present invention using an applicator so as to have a final thickness of 40 μm. After coating, it is dried in a hot air oven at 100° C. for 5 minutes to form an epoxy resin laminated sheet. On the epoxy resin of the epoxy resin laminated sheet, an acrylic polyester adhesive tape (manufactured by Nitto Denko Corporation, Nitto 31B tape, 19 mm width) was laminated as a support, and a universal testing machine "Autograph AG-" manufactured by Shimadzu Corporation was used. 1S", the peel force (N/19 mm) was measured at a peel angle of 180° and a tensile speed of 300 mm/min. From the peel force (N/19 mm)-test time (sec) graph obtained by the measurement, the average peel force at 5 to 10 sec was calculated. This measurement was performed 5 times, and the peel strength of the epoxy resin layer was evaluated by omitting the maximum and minimum values and taking the average value of the 3 measurements as the peel strength of the laminated polyester film (N/19 mm).
A: The peel strength of the epoxy resin layer is 1.2 N/19 mm or less.
B: The peel strength of the epoxy resin layer is greater than 1.2 N/19 mm and 1.5 N/19 mm or less.
C: The peel strength of the epoxy resin layer is greater than 1.5 N/19 mm and 3.0 N/19 mm or less.
D: The peel strength of the epoxy resin layer is greater than 3.0 N/19 mm.
As for the peel strength of the epoxy resin layer, A to C are good, and among them, A is the best.

(v) Surface defect after peeling of the epoxy resin layer Peeling surface (release surface) of the epoxy resin layer peeled from the three laminated polyester films used to determine the average value of the peeling force in the section (iv) The surface that was in contact with the resin layer) was observed with a scanning electron microscope (SEM) at a magnification of 5000 to confirm the presence or absence of surface defects with an equivalent circle diameter of 1 μm or more, and surface defects after peeling of the epoxy resin layer. evaluated.
A: No surface defects are observed in all 3 sheets B: Surface defects are observed in 1 out of 3 sheets C: Surface defects are observed in 2 out of 3 sheets D: Epoxy resin layers in which surface defects are observed in all 3 sheets As surface defects after peeling, A to C are good, and A is the best among them.

N. Evaluation of coating and peelability of green sheet (i) Preparation of ceramic slurry Barium titanate (trade name HPBT-1 manufactured by Fuji Titanium Industry Co., Ltd.) 100 parts by mass, polyvinyl butyral (trade name BL-1 manufactured by Sekisui Chemical Co., Ltd.) ), 5 parts by mass of dibutyl phthalate and 60 parts by mass of toluene-ethanol (mass ratio 30:30), glass beads with a number average particle diameter of 2 mm were added, and the mixture was mixed and dispersed in a jet mill for 20 hours. , and filtered to prepare a pasty ceramic slurry.

(ii) Green Sheet Formation The obtained ceramic slurry is applied on the surface of the laminated polyester film of the present invention by a die coater so as to have a final thickness of 1 μm, and dried to form a green sheet.

(iii) Coatability of ceramic slurry A green sheet is formed 10 times using the ceramic slurry shown in (ii) above, and the occurrence of repelling is visually evaluated, and the coatability of the ceramic slurry is evaluated from the number of occurrences. bottom.
A: Repelling occurred 0 times out of 10 times.
B: Repelling occurs 1 time or more and 3 times or less out of 10 times.
C: Repelling occurs 4 times or more and 5 times or less out of 10 times.
D: Repelling occurred 6 times or more out of 10 times.
As the ceramic slurry coatability, A to C are good, and A is the best among them.

(iv) Peelability of green sheet In the same manner as in (ii) above, the mixed ceramic slurry was coated on the surface of the laminated polyester film of the present invention with a die coater so as to have a final thickness of 1 μm. Dry to form a green sheet. On the green sheet of the green sheet laminated polyester film, an acrylic polyester adhesive tape (manufactured by Nitto Denko Corporation, Nitto 31B tape, 19 mm width) was laminated as a support, and a universal testing machine "Autograph AG" manufactured by Shimadzu Corporation was used. -1S", the peel force (N/19 mm) was measured at a peel angle of 180° and a tensile speed of 300 mm/min. From the peel force (N/19 mm)-test time (sec) graph obtained by the measurement, the average peel force at 5 to 10 sec was calculated. This measurement was performed 5 times, and the average value of the 3 measurements excluding the maximum and minimum values was defined as the peel strength of the laminated polyester film (N/19 mm), and the peel strength of the green sheet was evaluated.
A: Peel force of green sheet is 0.02 N/19 mm or more and 0.5 N/19 mm or less
B: Peel force of green sheet is greater than 0.5 N/19 mm and 1.2 N/19 mm or less C: Peel force of green sheet is greater than 1.2 N/19 mm and 2.0 N/19 mm or less D: Peeling of green sheet Force greater than 2.0N/19mm
As for the peel strength of the green sheet, A to C are good, and among them, A is the best.

(v) Surface defects after peeling of the green sheet Peeling surface (release resin layer) of the green sheet peeled from the three laminated polyester films used to determine the average value of the peeling force in section (iv) The surface that was in contact with the surface) was observed with a scanning electron microscope (SEM) at a magnification of 5000 to confirm the presence or absence of surface defects with an equivalent circle diameter of 1 μm or more, and evaluate the surface defects after peeling of the epoxy resin layer. bottom.
A: No surface defects found in all three sheets B: Surface defects found in one out of three sheets C: Surface defects found in two out of three sheets D: Surface defects found in all three green sheets As surface defects after peeling, A to C are good, and A is the best among them.

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] To dimethyl terephthalate (DMT), 1.9 mol of ethylene glycol and magnesium acetate tetrahydrate per 100 parts by weight of DMT were added, and phosphoric acid was added. 0.015 parts by weight was added to carry out heat transesterification. Subsequently, 0.025 parts by weight of antimony trioxide was added, and the mixture was heated and polycondensed under vacuum to obtain polyester pellets containing substantially no particles. The obtained melt-polymerized PET had a glass transition temperature of 81° C., a melting point of 255° C., and an intrinsic viscosity of 0.55.

Thereafter, the obtained polyester pellets were dried at 160° C. for 6 hours and crystallized, and then solid-phase polymerization was performed at 220° C. and a degree of vacuum of 0.3 Torr for 8 hours to obtain solid-phase polymerized PET. The resulting solid phase polymerized PET had a glass transition temperature of 81° C., a melting point of 255° C., and an intrinsic viscosity of 0.63.

[Production of MB-A] In the polymerization of PET-1 in the previous section, silica particles (silica-1) having an average primary particle diameter of 80 nm dispersed in ethylene glycol were dispersed in ethylene glycol so that the amount added to PET was 1% by mass. to obtain a PET base master pellet MB-A. The resulting melt-polymerized MB-A had a glass transition temperature of 81° C., a melting point of 255° C., and an intrinsic viscosity of 0.62.

[Production of MB-B to D] MB-B to D were obtained in the same manner as MB-A, except that the type of silica particles added was changed as shown in Table 1. The properties of the obtained MB-B to D were as shown in Table 1.

[Release agent (A)]
・Long-chain alkyl group-containing resin (a-1)
200 parts of xylene and 600 parts of octadecyl isocyanate were added to a four-necked flask and heated while stirring. From the time when xylene began to reflux, 100 parts of polyvinyl alcohol having an average degree of polymerization of 500 and a degree of saponification of 88 mol % was added little by little at intervals of 10 minutes over about 2 hours. After the addition of polyvinyl alcohol was completed, the mixture was further refluxed for 2 hours to terminate the reaction. When the reaction mixture was cooled to about 80° C. and added to methanol, the reaction product precipitated as a white precipitate. After repeating the operation of adding methanol again to precipitate several times, the precipitate was washed with methanol, dried and pulverized to obtain a long-chain alkyl group-containing resin (a-1: polymethylene as the main chain and side chains having an alkyl group having 18 carbon atoms). This was diluted with water and adjusted to 20% by mass.

・Long-chain alkyl group-containing resin (a-2)
In a 25 mL pressure-resistant glass polymerization ampoule, 2-hydroxyethyl acrylate (HEA) (manufactured by Kanto Chemical Co., Ltd.), α, α'-azobisisobutyronitrile (AIBN) (Kanto Chemical Co., Ltd.) as a polymerization initiator ) company), cumyl dithiobenzoate (CDB) as a RAFT agent, and toluene as a solvent, HEA/CDB/AIBN/toluene = 0.35/0.03/0.007/2.27 weight (g ). Next, after the mixed solution in the ampoule was degassed twice by freeze degassing, the ampoule was sealed and heated in an oil bath at 100° C. for 18 hours to obtain a reaction liquid containing a polymer.

Docosyl acrylate, AIBN as a polymerization initiator, and toluene as a solvent were added to the reaction solution in the ampoule at a weight (g) of docosyl acrylate/AIBN/toluene = 4.65/0.003/1.3. After freezing and degassing twice, the ampoule was sealed and heated at 100° C. for 48 hours. After that, the polymerization solution was added dropwise to 20 times the mass of hexane and stirred to precipitate a solid. The obtained solid was filtered out and vacuum-dried overnight at 40° C. to obtain a long-chain alkyl group-containing resin (long-chain alkyl group-containing resin (a-2) which is a block copolymer having an alkyl group with 22 carbon atoms. ).

The resulting long-chain alkyl group-containing resin (a-2) was emulsified as follows to obtain a water-based resin emulsion. 375 g of water was placed in a 1 L homomixer, 45 g of polyoxyethylene nonylphenyl ether, 30 g of polyoxyethylene polyoxypropylene glycol, 200 g of long-chain alkyl group-containing resin a1, and 150 g of toluene were sequentially added and heated to 70°C. and stirred evenly. This mixed solution was transferred to a pressurized homogenizer for emulsification, and the pressure was further reduced while heating to distill off the toluene.

[Resin or compound (B)]
・Acrylic resin (b-1)
Methyl methacrylate (α), hydroxyethyl methacrylate (β), urethane acrylate oligomer (manufactured by Negami Kogyo Co., Ltd., Artresin (registered trademark) UN-3320HA, the number of acryloyl groups is 6) (γ ) are charged at a mass ratio of (α)/(β)/(γ) = 94/1/5, and sodium dodecylbenzenesulfonate is added as an emulsifier by 2 masses per 100 mass parts in total of (α) to (γ). were added and stirred to prepare a mixed liquid 1. Next, a reactor equipped with a stirrer, a reflux condenser, a thermometer and a dropping funnel was prepared. A reaction apparatus was charged with 60 parts by weight of the mixed solution 1, 200 parts by weight of isopropyl alcohol, and 5 parts by weight of potassium persulfate as a polymerization initiator, and heated to 60° C. to prepare a mixed solution 2. Mixed solution 2 was held for 20 minutes while being heated at 60°C. Next, mixed solution 3 was prepared from 40 parts by weight of mixed solution 1, 50 parts by weight of isopropyl alcohol, and 5 parts by weight of potassium persulfate. Subsequently, using a dropping funnel, the mixed liquid 3 was dropped into the mixed liquid 2 over 2 hours to prepare a mixed liquid 4. After that, the mixed solution 4 was held for 2 hours while being heated to 60°C. After cooling the obtained mixed liquid 4 to 50° C. or lower, it was transferred to a container equipped with a stirrer and a pressure reducing device. 60 parts by weight of 25% aqueous ammonia and 900 parts by weight of pure water are added thereto, and the isopropyl alcohol and unreacted monomers are recovered under reduced pressure while heating to 60° C., and the acrylic resin (b -1) was obtained.

・Polyester resin (b-2)
An aqueous dispersion of a polyester resin having the following copolymer composition was prepared.
<Copolymerization component>
(Dicarboxylic acid component)
Dimethyl 2,6-naphthalenedicarboxylate: 88 mol%
Sodium dimethyl 5-sulfoisophthalate: 12 mol%
(Diol component)
Compound obtained by adding 2 mol of ethylene oxide to 1 mol of bisphenol S: 86 mol%
1,3-propanediol: 14 mol%

・Methylolated melamine resin (b-3)
Sanwa Chemical Co., Ltd., "Nikalac" (registered trademark) MW-035 (solid concentration: 70% by mass, solvent: water) was used.

- Silicone resin (b-4):
Coating agent containing a silicone component manufactured by Shin-Etsu Chemical Co., Ltd., model number X-62-7655 and coating agent containing a silicone component manufactured by Shin-Etsu Chemical Co., Ltd., model number X-62-7622 and Shin-Etsu Chemical Co., Ltd. Catalyst, Model No. CAT-7605, manufactured by Co., Ltd. was mixed in a weight ratio of 95:5:1.

- Fluorine-containing silicone resin (b-5):
A coating agent containing a silicone component manufactured by Shin-Etsu Silicone Co., Ltd., model number KR-400, was used.

[Particle component]
・Silica particles (c-1)
“Spherica” (registered trademark) 140 (silica particles, average particle size: 140 nm) manufactured by Catalysts and Chemicals Co., Ltd. was used.

・Silica particles (c-2)
Nippon Shokubai Co., Ltd. “Seahoster” (registered trademark) KEW-30 (silica particles, average particle size 300 nm).

[Preparation of coating compositions A to J]
The release agent (A), the resin or compound (B), and the particle component (C) obtained as described above were mixed at the solid content mass ratio shown in Table 2. Furthermore, in order to improve the coating properties on the polyester film, the coating compositions A to I contain a fluorine-based surfactant ("Plus Coat" RY-2 manufactured by GOO CHEMICAL INDUSTRY CO., LTD.), and the above mixed coating. Coating compositions A to I were prepared by adding 0.1 part by mass with respect to 100 parts by mass of the entire composition. Coating composition J was used as is.

(Example 1)
After PET-1 was dried under reduced pressure at 180° C. for 2.5 hours, it was blended so that the amounts of the P2 layer and P4 layer shown in Table 3 were obtained, supplied to each of the two extruders, and melt-extruded. After filtering with a filter, after joining so as to laminate two layers (P2 layer / P4 layer structure) in a feed block, electrostatic casting is performed on a cooling cast roll maintained at 35 ° C. through a T die. The film was wrapped with a non-stretched film and solidified by cooling to obtain an unstretched film. This unstretched film is guided between the opposing electrodes and the earth roll, nitrogen gas is introduced into the apparatus, and atmospheric pressure glow discharge is applied to the surface of the P2 layer under the condition that the treatment intensity (E value) is 220 W min / m ² . Plasma treatment was performed by

After the unstretched film after the treatment is passed through a static elimination roll whose roll temperature is set to 30° C., it is successively subjected to biaxial stretching and in-line coating under the conditions shown in Tables 3 and 4. First, it is stretched 3.7 times in the longitudinal direction, and then according to Table 3, the coating composition A is applied to the P2 layer surface, and the coating composition B is applied to the P4 layer surface by an in-line coating method. The P1 layer and P3 layer were formed by stretching 4.3 times in the width direction at a leading stretching temperature of 90 to 140° C. and heat-treating at 240° C. under a constant length. Thereafter, a relaxation treatment was applied in the width direction to obtain a laminated polyester film having a thickness of 35 μm.

Tables 5 and 6 show the structure of the obtained laminated polyester film, analysis of particles contained in the film, surface properties, and film properties. As shown in Table 7, production suitability and application suitability evaluation are as follows. The film was excellent in coating and peelability from the green sheet.

(Examples 2 and 3)
In Examples 2 and 3, a laminated polyester film having a thickness of 35 μm was obtained in the same manner as in Example 1, except that the treatment intensity of plasma treatment by atmospheric pressure glow discharge was changed as shown in Table 4. Tables 5 and 6 show the structure of the obtained laminated polyester film, analysis of particles contained in the film, surface properties, and film properties.
Evaluations of suitability for production and suitability for use are shown in Table 7. In Example 2, peeling of the release resin layer and surface defects were worse than in Example 1, but both were within the range of practical use. As for other properties, the film was good as in Example 1.
In Example 3, the surface scratches were worse than in Example 1, but both were within the range of practical use. As for other properties, the film was good as in Example 1.

(Examples 4-6)
In Examples 4 and 5, in the same manner as in Example 1 except that the coating composition containing the particles shown in Table 3 was used to form the P1 layer, which is a release resin layer, in Example 6, master pellet MB A laminated polyester film with a thickness of 35 m was obtained in the same manner as in Example 1 except that -A (containing silica-1) was added so as to have the particle content shown in Table 3. Tables 5 and 6 show the structure of the obtained laminated polyester film, analysis of particles contained in the film, surface properties, and film properties.
The production suitability and application suitability evaluations are shown in Table 7. In Examples 4 to 6, surface defects after peeling off the epoxy resin and the green sheet were worse than in Example 1, but both were within the practical range. . As for other properties, the film was good as in Example 1.

(Examples 7-9)
In Examples 7 to 9, a laminated polyester film having a thickness of 35 μm was obtained in the same manner as in Example 1 except that the coating composition shown in Table 3 was used to form the P1 layer, which is a release resin layer. Tables 5 and 6 show the structure of the obtained laminated polyester film, analysis of particles contained in the film, surface properties, and film properties.
The production suitability and application suitability evaluations are shown in Table 7. In Examples 7 and 9, the coatability of the epoxy resin and ceramic slurry, and in Example 8, the peelability of the epoxy resin and the green sheet compared to Example 1. Although it deteriorated, both were within the range of practical use. As for other properties, the film was good as in Example 1.

(Examples 10 and 11)
In Examples 10 and 11, the coating composition described in Table 3 was used to form the P1 layer, which is a release resin layer, and PET-1 was used instead of the coating composition as the P3 layer, and the master described in Table 1 was used. Pellets MB-B and MB-C are added so that the particle content in Table 3 is obtained, and the P2 layer and P4 layer are separately supplied to three extruders, melt-extruded, filtered with a filter, and then fed. The blocks were merged to form a laminate of P2 layer/P4 layer/P3 layer. In Example 11, the intensity of plasma treatment by atmospheric pressure glow discharge was changed as shown in Table 4. A laminated polyester film having a thickness of 35 μm was obtained in the same manner as in Example 1 except for the above. Tables 5 and 6 show the structure of the obtained laminated polyester film, analysis of particles contained in the film, surface properties, and film properties.

The production suitability and application suitability evaluations are shown in Table 7. In Example 10, the epoxy resin coatability was worse than in Example 1, but it was within the practical range. Better than 1. As for other properties, the film was good as in Example 1.

In Example 11, the peeling of the release resin layer, the coating properties of the epoxy resin, and the surface defects after peeling were worse than in Example 1, but were within the range of practical use. As for other properties, the film was good as in Example 1.

(Examples 12 and 13)
In Examples 12 and 13, a laminated polyester film having a thickness of 35 μm was obtained in the same manner as in Example 1, except that the slit width of the T-die was adjusted to obtain an unstretched film having thickness unevenness in the width direction. Tables 5 and 6 show the structure of the obtained laminated polyester film, analysis of particles contained in the film, surface properties, and film properties.

The production suitability and application suitability evaluations are shown in Table 7. In Examples 12 and 13, due to increased thickness unevenness, winding misalignment and surface defects after peeling off the epoxy resin and the green sheet were worse than in Example 1. However, it was within the range of practical use. As for other properties, the film was good as in Example 1.

(Example 14)
In Example 14, PET-1 was added to the P3 layer instead of the coating composition, and the master pellets MB-B and MB-C listed in Table 1 were added so that the particle content in Table 3 was obtained, and the P2 layer and P4 layer were formed. was separately supplied to three extruders, melted and extruded, filtered with a filter, and then joined to laminate the P2 layer / P4 layer / P3 layer in the feed block. to obtain a laminated polyester film having a thickness of 35 μm. Tables 5 and 6 show the structure of the obtained laminated polyester film, analysis of particles contained in the film, surface properties, and film properties.

The production suitability and application suitability evaluations are shown in Table 7. In Example 14, the winding misalignment was worse than in Example 1, but was within the range of practical use. As for other properties, the film was good as in Example 1.

(Example 15)
In Example 15, a laminated polyester film having a thickness of 35 μm was obtained in the same manner as in Example 1 except that the coating composition shown in Table 3 was used for the P3 layer. Tables 5 and 6 show the structure of the obtained laminated polyester film, analysis of particles contained in the film, surface properties, and film properties.

Evaluations of suitability for production and suitability for use are shown in Table 7. In Example 15, winding wrinkles, epoxy resin, and surface defects after peeling of the green sheet were worse than in Example 1, but were within the range of practical use. As for other properties, the film was good as in Example 1.

(Comparative example 1)
In Comparative Example 1, a laminated polyester film having a thickness of 35 μm was obtained in the same manner as in Example 1 except that the atmospheric pressure glow discharge treatment after obtaining the unstretched film was not performed. Tables 5 and 6 show the structure of the obtained laminated polyester film, analysis of particles contained in the film, surface properties, and film properties.

Evaluations of suitability for production and suitability for use are shown in Table 7. Comparative Example 1 was a film significantly inferior in terms of peeling of the release resin layer and surface defects after peeling off the epoxy resin and the green sheet.

(Comparative example 2)
In Comparative Example 2, a laminated polyester film with a thickness of 35 μm was obtained in the same manner as in Comparative Example 2, except that the thickness of the P1 layer, which is the release resin layer, was changed to 2 μm as shown in Table 4. Tables 5 and 6 show the structure of the obtained laminated polyester film, analysis of particles contained in the film, surface properties, and film properties.

The production suitability and application suitability evaluations are shown in Table 7, and Comparative Example 2 was a film significantly inferior in surface scratches.

(Comparative Example 3)
In Comparative Example 3, a laminated polyester film having a thickness of 35 μm was obtained in the same manner as in Comparative Example 3, except that the coating composition containing the particles shown in Table 3 was used as the P1 layer, which is the release resin layer. Tables 5 and 6 show the structure of the obtained laminated polyester film, analysis of particles contained in the film, surface properties, and film properties.

Evaluations of suitability for production and suitability for use are shown in Table 7. Comparative Example 3 was a film with significantly inferior surface defects after peeling of the green sheet.

(Comparative Example 4)
In Comparative Example 4, the P1 layer, which is a release resin layer, was not provided by an in-line coating method, and after obtaining a polyester film after successive stretching, it was provided by off-coating using the coating composition shown in Table 3. A laminated polyester film having a thickness of 35 μm was obtained in the same manner as in Example 1 except for the above. Tables 5 and 6 show the structure of the obtained laminated polyester film, analysis of particles contained in the film, surface properties, and film properties.

Evaluations of suitability for production and suitability for use are shown in Table 7. Comparative Example 4 was a film significantly inferior in release resin layer peeling, epoxy resin layer and ceramic slurry coatability.

(Comparative Example 5)
In Comparative Example 5, a laminated polyester film having a thickness of 35 μm was prepared in the same manner as in Example 1 except that the atmospheric pressure glow discharge treatment after obtaining the unstretched film was not performed and the P1 layer that was the release resin layer was not provided. Obtained. Tables 5 and 6 show the structure of the obtained laminated polyester film, analysis of particles contained in the film, surface properties, and film properties.

The production suitability and application suitability evaluations are shown in Table 7. Comparative Example 5 is a film with significantly inferior surface flaws, release resin layer peeling, peelability from the epoxy resin layer and green sheet, and surface defects after peeling. became.

The laminated polyester film of the present invention has a release resin surface with excellent smoothness, and has excellent adhesion between the release resin layer and the polyester film, so that it has excellent process transportability and winding properties, and epoxy resin and Due to its excellent coating and releasability from the green sheet, it is used as a release process film for interlayer insulating films in the process of manufacturing wiring boards and as a support film for green sheet molding in the process of manufacturing multilayer ceramic capacitors. It can be suitably used as a process film for manufacturing electronic parts.

1. Release resin layer (P1 layer)
2. Surface of release resin layer (side A)
3. Zero plane (average plane; height 0 nm) in scanning white light interference microscope measurement
4. 50 nm high line (R _{50 nm} )
5. 6. Protrusions present on the A surface. P2 layer 7 . P3 layer8. P4 layer 9 . laminated polyester film

Claims (13)

A laminated polyester film having a polyester film and a release resin layer (P1), wherein the release resin layer (P1) is on at least one surface layer of the polyester film, and the following requirements (1) to (3) A laminated polyester film that satisfies
(1) When the surface of the release resin layer (P1) is the A surface and the arithmetic mean surface roughness of the A surface is SaA (nm), SaA is 0.5 or more and 4.5 or less. .
(2) _N50nmA is 200 or less, where protrusions are present on the A surface and the number of protrusions having a height of 50 nm or more is _N50nmA (pieces/ ^mm2 ).
(3) CaA is 90 or more and 120 or less, where CaA (°) is the water contact angle of the surface A; When the film thickness is measured in the film width direction (the same direction as the film roll width direction), and the maximum value of the film thickness is D _MAX (μm) and the minimum value is D _MIN (μm), the following formula (1) The laminated polyester film according to claim 1, wherein the thickness unevenness ΔD (μm) represented by is 1.5 or less.
ΔD=D _MAX -D _MIN Expression (1) 1, wherein _CaAP (°) is 87° or more, where _CaAP (°) is the water contact angle of the A-side after performing Gakushin abrasion treatment five times on the A-side, or 2. The laminated polyester film according to 2 above. 4. The laminated polyester film according to any one of claims 1 to 3, wherein FA (N/19 mm) is a tape peeling force from the A side, and FA is 0.02 or more and 2.0 or less. 5. The laminated polyester film according to any one of claims 1 to 4, wherein SpA is 25 or more and 100 or less, where SpA (nm) is the maximum projection height on the A side. Any one of claims 1 to 5, wherein SaB is 3 or more and 30 or less when the film surface opposite to the A side is B side and the arithmetic average surface roughness of B side is SaB (nm). A laminated polyester film as described. The laminated polyester film according to any one of claims 1 to 6, wherein D _P1 is 20 or more and 100 or less, where D _P1 (nm) is the thickness of the release resin layer (P1). The laminated polyester film according to any one of claims 1 to 7, wherein the P1 layer contains no particles. The laminated polyester film according to any one of claims 1 to 8, wherein the P1 layer is provided by an in-line coating method. The laminated polyester film according to any one of claims 1 to 9, wherein when the polyester resin layer in contact with the P1 layer is the P2 layer, the P2 layer does not contain particles. The laminated polyester film according to any one of claims 1 to 10, which is used as a process film for manufacturing electronic parts. The laminated polyester film according to any one of claims 1 to 11, which is used as a release process film for an interlayer insulating film in the process of manufacturing a wiring board. The polyester film according to any one of claims 1 to 11, which is used as a support film for green sheet molding in the process of manufacturing a laminated ceramic capacitor.

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