Laminated Polyester Film

Abstract

[Problem] To provide a multilayered polyester film which has satisfactory bondability in all fields including the optical, packaging, and label fields and has excellent transparency (low haze) and in which the coating layer is excellent in terms of blocking resistance and anti-dusting property. [Solution] A multilayered polyester film which comprises a polyester film and, formed on at least one surface thereof, a coating layer formed from a coating fluid comprising a polyurethane resin, a polyester resin, and a crosslinking agent, and particles, the multilayered polyester film satisfying the following (1)-(4). (1) The coating thickness (d) is 0.03-1.0 μm. (2) The coating layer has, on the surface, six or more projections per mm2 which have a height of 0.01-0.50 μm and a (minor-axis length) / (major-axis length) ratio of 0.2-0.5. (3) The ratio of the maximum recess depth (V) of the coating-layer surface to the coating thickness (d), V / d, is less than 0.6. (4) The multilayered polyester film has a haze of 2.0% or less.

Description

[Technical Field]

[0001] The present invention relates to a laminated polyester film. More specifically, the present invention relates to a laminated polyester film having an easily adhesive coating layer that is excellent in transparency (low haze), anti-blocking properties of the coating layer, and particularly in particle shedding (powder shedding) of the coating layer, and is suitable for a wide range of applications, including optical applications, packaging, and labels.

[0002] Thermoplastic resin films, especially polyester films, have excellent mechanical properties, electrical properties, dimensional stability, transparency, and chemical resistance, and are therefore widely used in magnetic recording materials, packaging materials, solar cell applications, optical films such as antireflection films, diffusion sheets, and prism sheets used in flat displays, and films for label printing. However, because polyester films have a highly crystalline oriented surface, they have the disadvantage of poor adhesion to various paints, resins, and inks when processed for these applications. For this reason, a commonly used method involves applying various resins to the surface of the polyester film to provide a coating layer with high adhesive properties.

[0003] In addition, in order to ensure the transparency (low haze) of polyester films, the particle content in the film has been reduced as much as possible. However, when such polyester films are provided with coating layers with easy adhesion properties, the coating layers often come into contact with each other during storage in a roll, resulting in the problem of adhesion of the coating layers (blocking). As a countermeasure, it is known to include particles in the coating layer (see Patent Document 1).

[0004] Furthermore, from the viewpoint of polyester film transparency (low haze), it is desirable to minimize the amount of particles contained in the coating layer, and various proposals have been made regarding particle size or content (see Patent Documents 2 and 3). Another long-standing issue is dusting resistance. "Dusting" here refers to the troublesome phenomenon in which particles in the coating layer are scraped off and fall off the surface of the coating layer as powder when the rolls of a processing machine or the like rub against the coating surface of the film. Particle shedding not only deteriorates the properties of the coating layer surface, but also causes roll contamination, which ultimately transfers to the processed surface, creating problems. However, in recent years, efforts have been made to increase line speeds during various processing operations in order to reduce costs and save energy. As a result, the contact speed between the processing machine rolls and the film coating layer increases, making traditional measures to prevent dusting insufficient. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 10-11915 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-246855 [Patent Document 3] Japanese Patent Application Laid-Open No. 2003-291285 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in view of the problems of the prior art. That is, an object of the present invention is to provide a laminated polyester film that has good adhesion in all fields such as optical applications, packaging applications, and labels, and that has excellent transparency (low haze), blocking resistance of the coating layer, and resistance to powder shedding. [Means for solving the problem]

[0007] In the course of investigating the causes of the above problems in order to solve the above problems, the present inventors discovered that the problems of the present invention can be solved by providing a coating layer of a specific composition on at least one surface of a polyester film substrate and forming protrusions having a specific structure on the surface of the coating layer, which led to the completion of the present invention.

[0008] That is, the present invention comprises the following: 1. A laminated polyester film having a coating layer formed from a coating liquid containing a polyurethane resin, a polyester resin, a crosslinking agent and particles on at least one surface of a polyester film, and satisfying the following (1) to (4): (1) Coating thickness (d) is 0.03 μm or more and 1.0 μm or less (2) The surface of the coating layer has 6 protrusions per mm with a height of 0.01 to 0.50 μm and a minor axis / major axis ratio of 0.2 to 0.5. 2 End (3) The ratio (V / d) of the maximum depression depth (V) on the coating layer surface to the coating thickness (d) is less than 0.6. (4) The haze of the laminated polyester film is 2.0% or less. 2. The laminated polyester film according to claim 1, wherein the particles in the coating layer are fumed metal oxide particles. 3. The laminated polyester film according to the above item 1 or 2, wherein the crosslinking agent in the coating layer is a blocked isocyanate compound. [Effects of the Invention]

[0009] The laminated polyester film of the present invention has excellent adhesion to hard coat layers, lens layers, and ultraviolet (UV) curable resins such as ink, and is particularly excellent in adhesion to ultraviolet (UV) ink. The laminated polyester film of the present invention has good adhesion in all fields, including optical applications, packaging, and labels, and is excellent in transparency (low haze), blocking resistance of the coating layer, and particle shedding (dusting) of the coating layer. DETAILED DESCRIPTION OF THE INVENTION

[0010] In the present invention, the thickness (d) of the coating layer can be appropriately set within the range of 0.03 to 1.0 μm. However, in order to achieve both processability and adhesiveness, the range is preferably 0.03 to 0.8 μm, more preferably 0.03 to 0.5 μm, and even more preferably 0.05 to 0.3 μm. A coating layer thickness of 0.03 μm or more is preferred because it provides good adhesiveness. A coating layer thickness of 1.0 μm or less is preferred because it is less likely to cause blocking.

[0011] In the present invention, the surface of the coating layer has 6 protrusions per mm with a height of 0.01 to 0.50 μm and a minor axis / major axis ratio of 0.2 to 0.5. 2 It is preferable that the height and minor axis / major axis ratio of the protrusions are within the above ranges, and the number of protrusions is 6 / mm 2 In the above cases, blocking resistance and powder shedding resistance are good, which is preferable. Protrusions with a height of 0.01 μm or more are preferable because they improve blocking resistance. Furthermore, protrusions with a height of 0.50 μm or less are preferable because they reduce haze and provide good powder shedding resistance. The protrusion height is preferably 0.01 to 0.40 μm, and more preferably 0.01 to 0.30 μm. Protrusions with a minor axis / major axis ratio of 0.2 or more are preferable because they provide good blocking resistance. Protrusions with a minor axis / major axis ratio of 0.5 or less are preferable because they provide good powder shedding resistance. The minor axis / major axis ratio of the protrusions is preferably in the range of 0.2 to 0.4, and more preferably in the range of 0.2 to 0.3. The number of protrusions with a height of 0.01 to 0.50 μm and a minor axis / major axis ratio of 0.2 to 0.5 on the coating layer surface is 6 / mm 2 It is preferable that the number of protrusions having a height of 0.01 to 0.50 μm and a minor axis / major axis ratio of 0.2 to 0.5 be large on the surface of the coating layer, but from the viewpoints of haze suppression and powder shedding resistance, the number of protrusions is 6 to 100 / mm 2 is preferable, and more preferably 6 to 50 pieces / mm 2 , and more preferably 7 to 30 pieces / mm 2 , and most preferably 7 to 20 pieces / mm 2 is.

[0012] In the present invention, the ratio (V / d) of the maximum depression depth (V) on the coating layer surface to the coating thickness (d) is preferably less than 0.6. A ratio (V / d) of the maximum depression depth (V) to the coating thickness (d) of less than 0.6 is preferable because it provides good resistance to powder shedding. The ratio (V / d) is more preferably 0.5 or less, and even more preferably 0.4 or less. However, if the ratio is too small, the depression depth becomes less significant, so (V / d) is preferably 0.001 or more, and more preferably 0.003 or more.

[0013] In the present invention, the haze of the laminated polyester film is preferably 2.0% or less, but can be appropriately set within the range of 2.0% or less depending on the application. However, for optical applications such as lenses or hard coats, the haze is preferably 1.5% or less, and more preferably 1.2% or less. In general, for transparent films, the haze is preferably close to 0%, but it may be 0.1% or more, or even 0.2% or more.

[0014] (Polyester film base) In the present invention, the polyester resin constituting the polyester film substrate is polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, polytrimethylene terephthalate, etc., as well as copolymerized polyester resins in which a portion of the diol component or dicarboxylic acid component of the above-mentioned polyester resins is replaced with a copolymerization component such as the following. For example, the copolymerization component may include diol components such as diethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol, and polyalkylene glycol, and dicarboxylic acid components such as adipic acid, sebacic acid, phthalic acid, isophthalic acid, 5-sodium isophthalic acid, and 2,6-naphthalenedicarboxylic acid.

[0015] In the present invention, polyester resins suitable for use in the polyester film substrate are primarily selected from polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, and polyethylene-2,6-naphthalate. Among these polyester resins, polyethylene terephthalate is most preferred in terms of the balance between physical properties and cost. Furthermore, polyester film substrates made from these polyester resins are preferably biaxially oriented polyester films, which can improve chemical resistance, heat resistance, mechanical strength, and the like.

[0016] The catalyst for polycondensation used in producing the polyester resin is not particularly limited, but antimony trioxide is preferred because it is inexpensive and has excellent catalytic activity. It is also preferred to use a germanium compound or a titanium compound. More preferred polycondensation catalysts include catalysts containing aluminum and / or its compound and a phenolic compound, catalysts containing aluminum and / or its compound and a phosphorus compound, and catalysts containing an aluminum salt of a phosphorus compound.

[0017] Furthermore, the polyester film substrate in the present invention is not particularly limited in terms of its layer structure, and may be a single-layer polyester film, a two-layer structure having different components, or a polyester film substrate consisting of at least three layers, including an outer layer and an inner layer.

[0018] (coating layer) The laminated polyester film of the present invention preferably has a coating layer formed mainly from a polyurethane resin, a polyester resin, a crosslinking agent, and particles laminated thereon in order to improve adhesion to a hard coat layer, a lens layer, ink, etc. The coating layer may be formed on both sides of the polyester film, or on only one side of the polyester film with a coating layer of a different resin formed on the other side.

[0019] The coating layer of the present invention is mainly formed from a polyurethane resin, a polyester resin, a crosslinking agent, and particles, but is preferably formed from a polyurethane resin, a polyester resin, a crosslinking agent, and fumed metal oxide particles, and a particularly desirable form is formed from a polyurethane resin, a polyester resin, a blocked isocyanate-based crosslinking agent, and fumed metal oxide particles.

[0020] The mass ratio of the total solid content of the polyurethane resin and polyester resin to the crosslinking agent is preferably in the range of 90 / 10 to 10 / 90, more preferably 80 / 20 to 20 / 80, and even more preferably 70 / 30 to 30 / 70. When the total solid content of the polyurethane resin and polyester resin and the total solid content of the crosslinking agent is 100 parts by mass, a crosslinking agent content of 10 parts by mass or more is preferred because durability such as moist heat resistance is maintained. On the other hand, a total polyurethane resin and polyester resin content of 10 parts by mass or more relative to the total solid content is preferred because good adhesion is achieved. Furthermore, the particles are preferably contained in an amount of 0.1 to 15.0 parts by mass when the total sum of the polyurethane resin, polyester resin, and crosslinking agent is 100 parts by mass. When the particles are 0.1 part by mass or more, it is easier to achieve the desired number of protrusions in the present invention, which is preferred. Furthermore, scratch resistance and blocking resistance are preferred. Conversely, when the particles are contained in an amount of 15.0 parts by mass or less, the transparency of the film (low haze) is preferred.

[0021] The composition of each coating layer will be described in detail below. (Polyurethane resin) The polyurethane resin of the present application is a polyurethane resin derived from at least a polyol component, a polyisocyanate component, and, optionally, a chain extender. In particular, the polyurethane resin preferably has hydrophilic groups in the molecule or on the side chain to improve affinity with particles and impart water solubility or water dispersibility. "In the molecule" here refers to those present in the main chain or at the terminal of the polyurethane resin. Furthermore, "side chain" refers to those introduced onto a branched molecular chain after synthesis and polymerization, where one of the raw material components constituting the molecular chain has three or more terminal functional groups. Examples of hydrophilic groups that can be used include anionic groups such as sulfonic acid, phosphonic acid, and carboxylic acid; cationic groups such as quaternary amines; and nonionic groups such as oxyalkylene groups. In the present application, however, it is preferable to have carboxyl or oxyethylene groups in the molecule or on the side chain to improve affinity with particles.

[0022] The polyurethane resin having a carboxyl group that is preferably used in the present invention can be obtained by using a carboxyl group-containing polyol component as the main urethane component, and the polyurethane resin having an oxyethylene group can be obtained by using an oxyethylene group-containing polyol or monool.

[0023] Examples of such carboxyl group-containing polyol components include the following. Relatively high molecular weight compounds such as carboxyl group-containing polyalkylene glycols, carboxyl group-containing acrylic polyols, carboxyl group-containing polyolefin polyols, and carboxyl group-containing polyester polyols can be used. Relatively low molecular weight compounds such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, 2,2-dimethylolbutyric acid, and 2,2-dimethylolvaleric acid can also be used. Dimethylolpropionic acid and dimethylolbutanoic acid are particularly suitable for introducing carboxyl groups.

[0024] The carboxyl group-containing polyurethane resin preferably has an acid value of 10 to 60 mgKOH / g, more preferably 20 to 50 mgKOH / g. An acid value of 10 mgKOH / g or higher is preferred because it provides good affinity with particles and facilitates the formation of protrusions according to the present invention. Furthermore, the polyurethane resin itself has good hydrophilicity, resulting in good water solubility or water dispersibility, which is also preferred. Conversely, an acid value of 60 mgKOH / g or lower is preferred because it provides good water resistance to the coating layer and prevents adhesion of films to each other due to moisture absorption. Here, to compensate for the water solubility or water dispersibility of the polyurethane resin in the present invention, hydrophilic groups other than carboxyl groups, such as hydroxyl groups, oxyalkyl groups, sulfonic acid, phosphonic acid, and quaternary amines, may be introduced within a range that does not impair performance.

[0025] The carboxyl groups in the polyurethane resin may be neutralized with a basic compound. Examples of basic compounds used for neutralization include alkali metals such as sodium and potassium, alkaline earth metals such as magnesium and calcium, and organic amine compounds. Among these, organic amine compounds that easily dissociate from the carboxyl groups upon heating are preferred. Examples of organic amine compounds include ammonia, methylamine, ethylamine, propylamine, isopropylamine, butylamine, 2-ethylhexylamine, cyclohexylamine, dimethylamine, diethylamine, dipropylamine, diisopropylamine, dibutylamine, trimethylamine, triethylamine, triisopropylamine, tributylamine, and ethylenediamine, linear and branched primary, secondary, and tertiary amines having 1 to 20 carbon atoms, such as morpholine, N-alkylmorpholine, and pyridine, and hydroxyl group-containing amines such as monoisopropanolamine, methylethanolamine, methylisopropanolamine, dimethylethanolamine, diisopropanolamine, diethanolamine, triethanolamine, diethylethanolamine, and triethanolamine.

[0026] Examples of oxyethylene group-containing polyol components that are preferably incorporated into the polyurethane resin of the present invention include the following: polyethylene glycol, which is a polymer of itself; polyethylene glycol / polypropylene glycol copolymers, which are copolymers having other oxyalkylene groups; and polyethylene glycol / polypropylene glycol block copolymers, which are block copolymers with other resins; polyethylene glycol / polypropylene glycol block copolymers, polyethylene glycol / polyester block copolymers, etc. The oxyethylene group-containing monool component can be the above-mentioned polymers in which the hydroxyl groups have been partially blocked with alkyl ether groups or the like.

[0027] The content of oxyethylene groups in the polyurethane resin is in the range of 5 to 70% by mass, preferably in the range of 10 to 65% by mass, and more preferably in the range of 15 to 60% by mass. An oxyethylene group content of 5% by mass or more is preferred, as it provides good affinity between the polyurethane resin and the particles and good water dispersibility of the polyurethane resin itself. On the other hand, an oxyethylene group content of 70% by mass or less is preferred, as it prevents the affinity of the particles from becoming too high, and also provides good moist heat resistance and weather resistance of the coating film. Furthermore, when used as polyethylene glycol or polyethylene glycol alkyl ether, the number-average molecular weight of these polyols or monools is preferably 300 to 4,000, more preferably 400 to 3,000, and most preferably 500 to 2,000. An oxyethylene group content of 300 or more is preferred, as it improves the water dispersibility of the polyurethane resin. An oxyethylene group content of 4,000 or less is preferred, as it improves adhesion and powder shedding resistance.

[0028] As the main polyol component used for synthesizing and polymerizing the polyurethane resin in the present invention, it is preferable to use polyester polyols and polycarbonate polyols in addition to the polyoxyalkylene glycols mentioned above.

[0029] The number average molecular weight of the polyester polyol or polycarbonate polyol in the present invention is preferably 300 to 5000, more preferably 400 to 4000, and most preferably 500 to 3000. When it is 300 or more, ink adhesion can be improved, which is preferable. When it is 5000 or less, powder fall resistance can be improved, which is preferable.

[0030] The polyester polyol used in the present invention is preferably aliphatic or alicyclic. Therefore, examples of the dicarboxylic acid component of the polyester polyol include aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid. Examples of the diol component include aliphatic diols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, and neopentyl glycol, and alicyclic diols such as cyclohexanedimethanol. Among these, the present invention preferably primarily uses long-chain fatty acids longer than adipic acid and long-chain diols longer than pentanediol. However, tri- or higher functional polycarboxylic acids, polyols, or unsaturated or aromatic components may be used to the extent that they do not deteriorate the physical properties.

[0031] The polycarbonate polyol used in the present invention is preferably an aliphatic polycarbonate polyol. Examples of the aliphatic polycarbonate polyol include an aliphatic polycarbonate diol and an aliphatic polycarbonate triol, but an aliphatic polycarbonate diol is preferably used. Examples of the aliphatic polycarbonate diol used for synthesizing and polymerizing the urethane resin having a polycarbonate structure in the present invention include aliphatic polycarbonate diols obtained by reacting one or more diols such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, 1,8-nonanediol, neopentyl glycol, diethylene glycol, and dipropylene glycol with carbonates such as dimethyl carbonate, ethylene carbonate, and phosgene.

[0032] In order to synthesize and polymerize the polyurethane resin of the present invention, polyol components other than those described above can also be used. Examples of other polyol components include polyether polyols, polyolefin polyols, dimer polyols, and silicone polyols that do not contain ethylene chains. Among these, polyether polyols that do not contain ethylene chains and have relatively good compatibility with the main polyols described above are preferred.

[0033] Examples of polyisocyanates used in the synthesis and polymerization of the polyurethane resin of the present invention include aromatic aliphatic diisocyanates containing an aromatic ring, such as xylylene diisocyanate; alicyclic diisocyanates, such as isophorone diisocyanate, 4,4-dicyclohexylmethane diisocyanate, and 1,3-bis(isocyanatomethyl)cyclohexane; aliphatic diisocyanates, such as hexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate; modified polyisocyanates containing an isocyanurate bond, biuret bond, or allophanate bond, which are produced from diisocyanates; and polyisocyanates obtained by adding one or more diisocyanates to trimethylolpropane or the like in advance. The use of alicyclic diisocyanates or aliphatic diisocyanates is preferable to the use of aromatic aliphatic diisocyanates containing an aromatic ring, as this reduces the problem of yellowing.

[0034] Examples of chain extenders include glycols such as ethylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, and 1,6-hexanediol, polyhydric alcohols such as glycerin, trimethylolpropane, and pentaerythritol, diamines such as ethylenediamine, hexamethylenediamine, and piperazine, aminoalcohols such as monoethanolamine and diethanolamine, thioglycols such as thiodiethylene glycol, and water. Furthermore, small amounts of polyols and polyamines having three or more functional groups may also be used.

[0035] The polyurethane resin in the present invention may have a reactive group such as a blocked isocyanate at the end or in the side chain in order to improve hardness.

[0036] (polyester resin) The polyester resin contained in the coating layer of the present invention may be a linear one, but is more preferably a polyester resin whose constituent components are a dicarboxylic acid and a diol having a branched structure or a diol containing one or more ether bonds. The dicarboxylic acid referred to here includes, as its main component, terephthalic acid, isophthalic acid, or 2,6-naphthalenedicarboxylic acid, as well as aliphatic dicarboxylic acids such as adipic acid and sebacic acid, and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, and 2,6-naphthalenedicarboxylic acid.

[0037] Furthermore, the diol having a branched structure is a diol having a branched alkyl group, and examples thereof include 2,2-dimethyl-1,3-propanediol, 2-methyl-2-ethyl-1,3-propanediol, 2-methyl-2-butyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-methyl-2-isopropyl-1,3-propanediol, 2-methyl-2-n-hexyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-ethyl-2-n-butyl-1,3-propanediol, 2-ethyl-2-n-hexyl-1,3-propanediol, 2,2-di-n-butyl-1,3-propanediol, 2-n-butyl-2-propyl-1,3-propanediol, and 2,2-di-n-hexyl-1,3-propanediol.

[0038] Further, examples of diols containing one or more ether bonds include condensates of alkylene glycols such as diethylene glycol, triethylene glycol, and dipropylene glycol, and ethylene oxide or propylene oxide adducts of bisphenols. There are no particular restrictions on the number of ether bonds in the molecule, but since this reduces the strength or glass transition point of the polyester resin, it is preferable that the number be four or less, and more preferably two or less.

[0039] In the polyester resin, the branched diol component or the diol component containing one or more ether bonds, which is a more preferred embodiment of the present invention, is preferably contained in a proportion of 10 mol % or more, and more preferably 20 mol % or more, of the total polyol components. A proportion of 10 mol % or more is preferable because crystallinity is not too high and the adhesiveness of the coating layer is maintained. The upper limit of the aforementioned diol component in the total polyol components is preferably 80 mol % or less, more preferably 70 mol % or less. A proportion of 80 mol % or less is preferable because there is no risk of an increase in the concentration of oligomer by-products and the transparency of the coating layer is obtained. Ethylene glycol is the most preferred glycol component other than the above-mentioned diol component. Small amounts of diols such as propylene glycol, butanediol, hexanediol, or 1,4-cyclohexanedimethanol, or polyols having three or more hydroxyl groups in the molecule, such as triethanolpropane, glycerin, and diglycerin, may also be used.

[0040] The dicarboxylic acid as a constituent component of the polyester resin is most preferably terephthalic acid or isophthalic acid. In addition to the dicarboxylic acid, in order to impart water dispersibility to the polyester resin, it is preferable to copolymerize a dicarboxylic acid component having a sulfonic acid group in the range of 1 to 10 mol %, such as sulfoterephthalic acid, 5-sulfoisophthalic acid, and 5-sodium sulfoisophthalic acid.

[0041] In the present application, a polyurethane resin and a polyester resin are used in the coating layer. The mixing ratio of the solid content of the polyurethane resin to the polyester resin is preferably 90 / 10 to 10 / 90 by mass, more preferably 80 / 20 to 20 / 80. When the total mass of the solid content of the polyurethane resin and the polyester resin is 100 parts by mass, a mass ratio of the polyester resin of 10 parts by mass or more maintains the toughness of the coating film, facilitates the formation of the protrusions and depressions of the present application, and provides good adhesion between the coating layer and the polyester film substrate, which is preferable. Furthermore, a mass ratio of the polyurethane resin of 10 parts by mass or more maintains the extensibility of the coating film, facilitates the formation of the protrusions and depressions of the present application, and provides good adhesion to ink, etc., which is preferable.

[0042] (Crosslinking agent) As the crosslinking agent of the present invention, known compounds such as isocyanate-based, epoxy-based, melamine-based, oxazoline-based, and carbodiimide-based compounds can be used. The use of a crosslinking agent can further improve powder shedding resistance. Furthermore, as the crosslinking agent, isocyanate-based compounds are preferred in terms of reactivity with polyurethane resins or polyester resins, improving the crosslink density of the coating film, and forming the specific protrusions of the present invention through affinity with particles, and blocked isocyanate-based compounds are particularly preferred. Blocked isocyanate-based compounds are particularly preferred in that they improve stability in the coating liquid state and facilitate the formation of the specific protrusions of the present invention by changing the crosslinking reaction initiation temperature depending on the composition of the blocking agent. Details will be described later.

[0043] Examples of the blocking agent include bisulfite compounds such as sodium bisulfite, pyrazole compounds such as 3,5-dimethylpyrazole, 3-methylpyrazole, 4-bromo-3,5-dimethylpyrazole, and 4-nitro-3,5-dimethylpyrazole, phenols such as phenol and cresol, aliphatic alcohols such as methanol and ethanol, active methylenes such as dimethyl malonate and acetylacetone, mercaptans such as butyl mercaptan and dodecyl mercaptan, acid amides such as acetanilide and acetic acid amide, lactams such as ε-caprolactam and δ-valerolactam, acid imides such as succinimide and maleimide, oximes such as acetaldoxime, acetone oxime, and methyl ethyl ketoxime, and amines such as diphenylaniline, aniline, and ethyleneimine.

[0044] Furthermore, it is preferable to introduce a hydrophilic group into the blocked isocyanate crosslinking agent so that it can be easily mixed with a water-soluble or water-dispersible polyurethane resin or polyester resin. Furthermore, the introduction of an anionic group such as a carboxyl group or a sulfonic acid group, or a nonionic group such as an oxyalkyl group, is preferable for the hydrophilicity. These hydrophilic groups can be prepared by previously reacting the polyisocyanate, which serves as the base of the blocked isocyanate, with a compound having a hydrophilic group and a reactive group such as a hydroxyl group or an amine group.

[0045] The upper limit of the dissociation temperature of the blocking agent is preferably 200°C, more preferably 180°C, even more preferably 160°C, particularly preferably 150°C, and most preferably 120°C. The blocking agent dissociates during the drying process after application of the coating solution or, in the case of in-line coating, during the film formation process, generating regenerated isocyanate groups. This promotes a crosslinking reaction with polyurethane resins and improves the crosslinked state of the coating film.

[0046] Examples of blocking agents preferably used in the present invention, which have a blocked isocyanate dissociation temperature of 120°C or less, include the above-mentioned sodium bisulfite, pyrazole compounds such as 3,5-dimethylpyrazole and 3-methylpyrazole, malonic acid ester compounds such as dimethyl malonate and diethyl malonate, and oxime compounds such as acetone oxime and methyl ethyl ketoxime. Among these, oxime compounds, malonic acid ester compounds, and pyrazole compounds are preferred from the viewpoints of moist heat resistance and yellowing.

[0047] The blocked isocyanate is preferably a difunctional or higher functional one, and a trifunctional or higher functional one is more preferred from the viewpoint of the crosslinkability of the coating film.

[0048] The tri- or higher functional polyisocyanate, which is the precursor of the blocked isocyanate in the present invention, can be suitably obtained by introducing an isocyanate monomer, such as a biuret, isocyanurate, or adduct obtained by modifying an isocyanate monomer, such as an aromatic diisocyanate, aliphatic diisocyanate, araliphatic diisocyanate, or alicyclic diisocyanate, each having two isocyanate groups. The biuret form is a self-condensation product having a biuret bond formed by the self-condensation of an isocyanate monomer, and examples thereof include the biuret form of hexamethylene diisocyanate. The isocyanurate is a trimer of an isocyanate monomer, and examples thereof include a trimer of hexamethylene diisocyanate, a trimer of isophorone diisocyanate, and a trimer of tolylene diisocyanate. The adduct refers to a tri- or higher functional isocyanate compound obtained by reacting an isocyanate monomer with a tri- or higher functional low-molecular-weight active hydrogen-containing compound, and examples thereof include a compound obtained by reacting trimethylolpropane with hexamethylene diisocyanate, a compound obtained by reacting trimethylolpropane with tolylene diisocyanate, a compound obtained by reacting trimethylolpropane with xylylene diisocyanate, and a compound obtained by reacting trimethylolpropane with isophorone diisocyanate.

[0049] Examples of the isocyanate monomer include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, 1,4-naphthylene diisocyanate, phenylene diisocyanate, tetramethylxylylene diisocyanate, 4,4'-diphenylether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, and 2,2'-diphenylpropane-4,4'-diisocyanate. Examples of suitable diisocyanates include aromatic diisocyanates such as 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, 4,4'-diphenylpropane diisocyanate, 3,3'-dimethoxydiphenyl-4,4'-diisocyanate, and xylylene diisocyanate, alicyclic diisocyanates such as isophorone diisocyanate, 4,4-dicyclohexylmethane diisocyanate, and 1,3-bis(isocyanatomethyl)cyclohexane, and aliphatic diisocyanates such as hexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate. Aliphatic and alicyclic isocyanates and their modified products are preferred in terms of transparency, yellowing resistance, adhesion, and moist heat resistance.

[0050] In the present invention, two or more types of crosslinking agents may be used in combination. In particular, by using two or more different blocked isocyanate crosslinking agents in combination, it becomes possible to provide a difference in the crosslinking initiation temperature, and it is possible to control the crosslinking density to a certain extent, thereby further improving the performance of the present invention.

[0051] In the present invention, other resins may be used in combination as long as the performance is not affected. Examples of resins that can be used in combination include polyurethane resins other than polycarbonate, alkyd resins, acrylic resins, cellulose resins, polyolefin resins, and polyacetal resins.

[0052] (particle) In the present invention, the surface of the coating layer has 6 protrusions per mm with a height of 0.01 to 0.50 μm and a minor axis / major axis ratio of 0.2 to 0.5. 2 In order to achieve the above and a ratio (V / d) of the maximum depression depth (V) on the coating layer surface to the coating thickness (d) of less than 0.6, it is preferable to use aggregates of metal oxide fine particles as the particles, as will be described in detail later.

[0053] The method for producing metal oxide fine particles may be a dry method or a wet method, etc., without any particular problem. After producing aggregates of fine particles, the aggregates may be adjusted to an optimum size for the present application by a dispersion process or the like, or after producing fine particles, aggregates of an optimum size may be produced by a separate aggregation operation. A dry method, which allows the aggregates to be produced in advance, is preferred because the aggregates of an optimum size for the present application can be easily adjusted by a dispersion process or the like, and among these, the use of fumed metal oxide is particularly preferred. Regarding the size of the metal oxide fine particles, when they are made into single fine particles, the average particle size is preferably in the range of 5 to 150 nm, more preferably in the range of 10 to 100 nm, and even more preferably in the range of 20 to 90 nm. Alternatively, as a characteristic value of the aggregate, the BET value is 20 to 500 nm. 2 / g, and 25 to 300m 2 / g is more preferable, and furthermore, 30 to 200m 2 / g is preferred. The particles used in the present invention are preferably adjusted to a preferred range of average particle size of the aggregates to form protrusions having the above-mentioned specific height and minor axis / major axis ratio. The preferred average particle size of the aggregates is 80 to 600 nm, more preferably 100 to 400 nm, and most preferably 150 to 350 nm. Furthermore, in order to achieve the ratio (V / d) of the maximum recess depth (V) on the coating layer surface to the coating thickness (d) of the present invention, the surface polarity of the metal oxide fine particles is preferably hydrophilic in terms of affinity for polyurethane resins and polyester resins. The constituent elements of the metal oxide fine particles are not particularly limited, and examples include titanium oxide, aluminum oxide, zirconia oxide, silicon oxide, etc., which are commonly used as particles. However, silicon oxide, i.e., silica, is preferred in terms of particle hardness, specific gravity, and cost. That is, in the present invention, the BET value is 20 to 500 m 2 It is preferable to use a dispersion in which fumed silica in the range of 1 / g is dispersed in a solvent such as water to have an average particle size of 80 to 600 nm using a disperser.

[0054] To achieve the preferred number of protrusions in the present invention, the particle concentration of the metal oxide fine particle aggregates in the coating layer is preferably 0.05 to 5.0 parts by mass based on 100 parts by mass of the total solid content of the polyurethane resin, polyester resin, and crosslinking agent. More preferably, it is 0.1 to 4.0 parts by mass. Furthermore, particles other than the metal oxide fine particle aggregates may be used in combination within an appropriate range. In particular, the use of colloidal silica as monodispersed silica particles is preferred for improving scratch resistance. The average particle diameter of the colloidal silica is preferably in the range of 3 to 100 nm, more preferably 5 to 80 nm. The particle concentration of these colloidal silica particles in the coating layer is preferably 1.0 to 20.0 parts by mass based on 100 parts by mass of the total solid content of the polyurethane resin, polyester resin, and crosslinking agent. More preferably, it is 3.0 to 15.0 parts by mass.

[0055] (additives) The coating layer of the present invention may contain known additives, such as surfactants, antioxidants, heat stabilizers, weather stabilizers, ultraviolet absorbers, organic lubricants, pigments, dyes, organic or inorganic particles, antistatic agents, and nucleating agents, within the range that does not impair the effects of the present invention.

[0056] In the present invention, in order to further improve the blocking resistance of the coating layer, it is also a preferred embodiment to add particles other than those described above to the coating layer. Examples of particles to be contained in the coating layer in the present invention include titanium oxide, barium sulfate, calcium carbonate, calcium sulfate, silica, alumina, talc, kaolin, clay, etc., or mixtures thereof, and further include inorganic particles such as calcium phosphate, mica, hectorite, zirconia, tungsten oxide, lithium fluoride, calcium fluoride, etc., used in combination with other general inorganic particles, and organic polymer particles such as styrene-based, acrylic-based, melamine-based, benzoguanamine-based, and silicone-based particles.

[0057] The average particle size of the other particles in the coating layer (average particle size based on the number of particles as determined by a scanning electron microscope (SEM); the same applies hereinafter) is preferably 0.02 to 2.0 μm, more preferably 0.04 to 1.00 μm. When the average particle size of the inactive particles is 0.04 μm or more, it is easy to form irregularities on the film surface, which further improves the handling properties of the film, such as slipperiness and winding ability, and improves processability during lamination, which is preferable. On the other hand, when the average particle size of the inactive particles is 2.00 μm or less, it is preferable because the particles are less likely to fall off. The particle concentration in the coating layer is preferably 1 to 20 parts by mass of the solid components, when the total solid content of the polyurethane resin, polyester resin, and crosslinking agent is 100 parts by mass.

[0058] The average particle size of other particles was measured by observing particles on the cross section of the laminated polyester film with a scanning electron microscope, observing 30 particles, and determining the average particle size as the average value.

[0059] The shape of the other particles is not particularly limited as long as it satisfies the objectives of the present invention, and spherical particles and irregular, non-spherical particles can be used. The particle size of irregular particles can be calculated as the equivalent circle diameter. The equivalent circle diameter is calculated by dividing the observed particle area by π, calculating the square root, and then multiplying it by two.

[0060] (Manufacturing of laminated polyester film) The method for producing the laminated polyester film of the present invention will be described using an example in which a polyethylene terephthalate (hereinafter sometimes abbreviated as PET) film substrate is used, but the present invention is not limited to this.

[0061] After thorough vacuum drying, the PET resin is fed into an extruder, and the molten PET resin at approximately 280°C is extruded from a T-die onto a rotating cooling roll in the form of a sheet. It is then cooled and solidified using an electrostatic application method to obtain an unstretched PET sheet.

[0062] The unstretched PET sheet may be a single-layer structure or a multi-layer structure formed by coextrusion. Various additives may be incorporated into the polyester resin of each layer as needed, as long as the effects of the present invention are achieved. Examples of additives include antioxidants, light-resistant agents, antigelling agents, organic wetting agents, antistatic agents, UV absorbers, and surfactants.

[0063] In addition, in order to adjust the handling properties of the film, such as slipperiness, winding property, and blocking resistance, and the abrasion properties, such as abrasion resistance and scratch resistance, it is preferable that the content of inert particles in the substrate film is as small as possible, as long as the haze is within the range of the present invention, and for high clarity.Therefore, it is a preferred embodiment to have a multilayer structure in which particles are contained only in the surface layer of the film, or to have the film essentially free of particles and contain fine particles only in the coating layer.Inert particles may be contained in the substrate film or in the surface layer of the film.

[0064] The resulting unstretched PET sheet is uniaxially or biaxially stretched to achieve crystal orientation. For example, in the case of biaxial stretching, the sheet is stretched 3.0 to 5.0 times in the machine direction using rolls heated to 80 to 120°C to obtain a uniaxially stretched PET film. The film is then gripped at its edges with clips and introduced into a hot air zone heated to 80 to 180°C, where it is stretched 3.0 to 5.0 times in the width direction. In the case of uniaxial stretching, the unstretched PET sheet is stretched 3.0 to 5.0 times in a tenter. After stretching, the sheet is subsequently introduced into a heat treatment zone at 180 to 230°C, where it is heat-treated to complete the crystal orientation.

[0065] As described above, in the present application, the coating layer is preferably formed prior to the stretching step in film production, i.e., by applying a coating solution to at least one side of an unstretched or uniaxially stretched PET film, followed by subsequent steps such as a stretching step. As described above, the aggregates of metal oxide fine particles in the coating layer immediately after coating are stretched together with the resin component of the coating layer by a stretching step at a specific temperature for the PET film, thereby achieving the protrusion shape described herein, with a height of 0.01 to 0.50 μm and a minor axis / major axis ratio of 0.2 to 0.5. The temperature during the stretching step reduces the stress during stretching of the resin component of the coating layer, so that only the peripheral portions of the particle aggregates deform, with minimal deformation in the central portions of the aggregates, enabling the formation of protrusions with a specific protrusion height and minor axis / major axis ratio. Therefore, the stretching ratio is preferably set within the range of 3 to 5. Furthermore, the use of a polyurethane resin and a crosslinking agent, particularly a blocked isocyanate, in the coating layer is preferred in order to achieve the desired depth of the depressions on the coated surface of the present invention. That is, although the detailed mechanism is unknown, it is assumed that the presence of polyurethane resin and crosslinking agent in the coating layer suppresses breakage of particle aggregates due to deformation during stretching, and that the depressions in the coating layer that occur when particle aggregates break and fall out of the coating layer are small and shallow.

[0066] Furthermore, among various crosslinking agents, from the viewpoint of adjusting the affinity with particle aggregates and deformability, it is preferable to use a blocked isocyanate-based crosslinking agent, which forms crosslinking bonds such as urethane groups with various reactive groups such as hydroxyl groups on the particle surface and whose reaction initiation temperature can be adjusted by selecting a blocking agent.

[0067] Any known method can be used to apply the coating solution to the PET film. Examples include reverse roll coating, gravure coating, kiss coating, die coating, roll brushing, spray coating, air knife coating, wire bar coating, pipe doctor coating, impregnation coating, and curtain coating. These methods can be used alone or in combination.

[0068] The upper limit of the haze of the laminated polyester film of the present invention is preferably 2.0%, more preferably 1.8%, still more preferably 1.5%, and particularly preferably 1.2%. A haze of 2.0% or less is preferable in terms of transparency, and the film can be suitably used for optical film applications where transparency is required. [Example]

[0069] Next, the present invention will be described in detail using examples and comparative examples, but the present invention is not limited to the following examples. First, the evaluation methods used in the present invention will be described below.

[0070] (1) Acid value The acid value of the polyurethane resin was measured by the titration method described in JIS K1557-5:2007. However, in the case of carboxyl groups neutralized with amines or the like, measurements were performed after removing the amines by high-temperature treatment or treating with hydrochloric acid or the like in advance to liberate and remove the amines. In the case of crosslinking agents, measurements were performed after reacting reactive groups such as isocyanates with amines or the like in advance. If the resin to be measured had poor solubility in the solvent isopropanol, N-methylpyrrolidone was used instead. In any of the above treatments, sufficient comparison measurements were performed.

[0071] (2) Polyethylene glycol content The polyethylene glycol content in the polyurethane resin was calculated by the following method. The polyethylene glycol content was calculated from the proton integral ratio of the methylene at the α-position of the oxygen atom of polyethylene glycol by H-NMR using triphenylmethane as the standard substance and DMSO-d6 as the solvent. However, if it is difficult to calculate the polyethylene glycol content by the above-mentioned method due to solvent solubility or the like, there is no problem in calculating it by another method as long as it is performed under sufficient verification.

[0072] (3) Average particle size The particle size distribution of the dispersion was measured using a high-concentration measurement unit (SALD-HC75) of a nanoparticle size distribution analyzer (SALD-7500nano) (Shimadzu Corporation). The particle size distribution was calculated based on the LDR (Light Intensity Distribution Reproduction Method), and the average particle size was determined from the calculation results by selecting a particle refractive index of 1.50 for silica and 1.75 for aluminum oxide.

[0073] (4) Coating layer thickness The laminated film was cut out, embedded in resin, and cut into ultrathin sections using an ultramicrotome. The sections were then directly observed at a magnification of 20,000x using a JEOL JEM2100 transmission electron microscope, and the thickness of the coating layer was measured from the TEM images. When the coating layer was too thin to measure using the above method, the coating layer mass per unit area was determined using a fluorescent X-ray analyzer based on a previously prepared calibration curve for silicon (Si). The coating layer mass was then converted to thickness using a coating layer specific gravity of 1.2.

[0074] (5) Number of protrusions Using a non-contact surface shape measurement system (VertScan R550H-M100, manufactured by Ryoka Systems Co., Ltd.), the surface of the coating layer was measured under the following conditions, and particle analysis was performed. From the characteristic values ​​of each protrusion listed from the measurement results, the number of particles with a height of 0.01 to 0.50 μm and a minor axis / major axis ratio of 0.2 to 0.5 was determined. The measurement location was changed and the number of protrusions per screen was determined in the same way five times in total. The average number of protrusions was calculated from 5 measurements. 2 The number of projections was converted to the number of projections per hit, and the number of projections was calculated to one decimal place by rounding off to the nearest decimal place. (Measurement conditions) Measurement mode: WAVE mode Objective lens: 10x 0.5x Tube Lens ·Measurement area 936μm×702μm (Analysis conditions) Surface correction: 4th order correction ·Protrusion analysis Type sudden analysis Image correction: None Processing height threshold: 0.01 μm Protrusion shaping: None Reference height: zero plane

[0075] (6) Depth of depression From the above measurement results, the area roughness parameter Valley [um] was calculated. The average value of five measurements was calculated in the same manner as above. The average value was rounded to two decimal places to obtain the value to two decimal places, which was used as the depression depth (μm).

[0076] (7) Resistance to powder shedding The films produced in the Examples and Comparative Examples were cut into strips (5 cm (film width direction) x 15 cm (film length direction = machine direction)) to prepare sample film pieces. These sample film pieces were attached to a rub fastness tester (Crockmeter C-1D, manufactured by Daiei Scientific Instruments Co., Ltd.) and slid back and forth 10 times at a speed of 10 seconds under a load of 9 N using aluminum foil (thickness 80 μm, arithmetic average surface roughness 0.03 μm) on the load head. The obtained sample film piece and aluminum foil were placed on a black mount, and whether powder had fallen off was visually judged according to the following criteria. ◎: No whitening was observed on the sample film piece or aluminum foil on the black backing. ◯: No whitened areas can be seen on the sample film piece on the black backing, but whitened areas can be faintly seen on the aluminum foil. △: A faint whitened area can be seen on the sample film piece on the black mount, and a whitened area can be seen on the aluminum foil. ×: Whitened areas were observed on the sample film piece and aluminum foil on the black mount.

[0077] (8) Hayes The haze of the obtained laminated polyester film was measured in accordance with JIS K 7136:2000 using a turbidity meter (NDH5000, manufactured by Nippon Denshoku Corporation).

[0078] (9) Blocking resistance Two film samples were placed together with the coating surfaces facing each other, and a load of 98 kPa was applied. The samples were then left in close contact for 24 hours in an atmosphere at 50° C. The films were then peeled off, and the peeling condition was evaluated according to the following criteria. ◯: The coating layer was not transferred and could be easily peeled off. △: The coating layer is maintained, but the surface layer of the coating layer is partially transferred to the opposing surface. ×: The two films were stuck together and could not be separated, or even if they could be separated, the film substrate was cleaved.

[0079] (10) Adhesion to UV ink On the coating layer of the laminated polyester film, UV ink [manufactured by T&K TOKA Corporation, product name "BEST CURE UV161 Indigo S" or "BEST CURE UV161 White S"] was printed using a printing machine [manufactured by Akira Manufacturing Co., Ltd., product name "RI Tester"] with an ink pipette of 4 graduations and a two-division roll, and then the film with the ink layer was exposed to 100 mJ / cm using a high-pressure mercury lamp. 2 The ink was then irradiated with ultraviolet light at 100 slits, curing the ultraviolet-curable ink. Next, using a cutter guide with a gap of 2 mm, 100 grid-shaped cuts were made on the ink layer surface, penetrating the ink layer and reaching the film substrate. Next, cellophane adhesive tape (Nichiban, No. 405; 24 mm wide) was applied to the grid-shaped cuts. The cellophane adhesive tape was then peeled perpendicularly from the ink layer surface of the ink laminated film, and the number of squares peeled from the ink layer surface of the ink laminated film was counted visually, and the adhesion between the ink layer and the film substrate was calculated using the following formula. Note that partially peeled squares were also counted as peeled squares, and the ink adhesion was calculated using the following formula. Ink adhesion (%) = 100 - (number of peeled squares) The ink adhesion (%) was classified as follows, with ⊚ and ◯ being considered acceptable. ◎: 100%, ○: 99-96%, △: 95-80%, ×: 79-0%

[0080] (11) Adhesion to hard coat layer Opstar Z7503 (Arakawa Chemical Industries, Ltd.), a UV-curable hard coating agent, was applied onto the coating layer of the laminated polyester film using a #5 wire bar and dried at 80°C for 1 minute. Next, the coated film was irradiated with 100 mJ / cm using a high-pressure mercury lamp. 2 The film was irradiated with ultraviolet light of 1000 kJ / min to obtain a hard coat film. Next, using a cutter guide with a gap of 2 mm, 100 grid-shaped cuts were made on the hard coat layer surface, penetrating the hard coat layer and reaching the film substrate. Next, cellophane adhesive tape (Nichiban, No. 405; 24 mm wide) was applied to the grid-shaped cut surface and rubbed with an eraser to ensure complete adhesion. The cellophane adhesive tape was then peeled vertically from the hard coat layer surface of the hard coat laminate film, and the number of squares peeled from the hard coat layer surface of the hard coat laminate film was counted visually, and the adhesion between the hard coat layer and the film substrate was calculated using the following formula. Partially peeled squares were also counted as peeled squares, and the hard coat adhesion was calculated using the following formula. Hard coat adhesion (%) = 100 - (number of peeled squares) The hard coat adhesion (%) was classified as follows, with ⊚ and ◯ being acceptable. ◎: 100%, ○: 99-96%, △: 95-80%, ×: 79-0%

[0081] (12) Moisture and heat resistance UV ink-coated or hard coat-coated films prepared in the same manner as in (10) and (11) above were left in an environment of 80°C and 80% RH with the coated surface vertical and without any other films in contact with the coated surface for 500 hours. After treatment, the films were left in an environment of 23°C and 65% RH for 10 minutes with no other films in contact with the coated surface. Immediately after the time had passed, the adhesion of the coated surface was evaluated in the same manner as above.

[0082] (Polyurethane) (Polymerization of polyurethane resin PU-1) A four-neck flask equipped with a stirrer, Dimroth condenser, nitrogen inlet tube, silica gel drying tube, and thermometer was charged with 63.0 parts by mass of hydrogenated m-xylylene diisocyanate, 21.0 parts by mass of dimethylolpropanoic acid, 12.5 parts by mass of 1,6-hexanediol, 147.0 parts by mass of a 1,6-hexanediol polycarbonate diol having a number average molecular weight of 2000, and 110 parts by mass of methyl ethyl ketone as a solvent. The mixture was stirred at 75°C for 3 hours under a nitrogen atmosphere, and it was confirmed that the reaction solution had reached the required amine equivalent. Next, the reaction solution was cooled to 40°C, and 16.6 parts by mass of triethylamine was added to obtain a polyurethane polymer solution. Next, 500 g of water was added to a reaction vessel equipped with a homodisper capable of high-speed stirring, and the temperature was adjusted to 25°C. The mixture was stirred for 2000 min. -1 While stirring and mixing at 50°C, the polyurethane polymer solution was added and dispersed in water. The solvent, methyl ethyl ketone, was then removed under reduced pressure. The concentration was adjusted with water to prepare a polyurethane resin (PU-1) solution with a solids content of 35% by mass. The acid value of the polyurethane resin PU-1 was 36.0 mgKOH / g.

[0083] (Polymerization of polyurethane resin PU-2) A polyurethane resin (PU-2) solution with a solids content of 35% by mass was prepared in the same manner as for polyurethane resin PU-1, except that the raw materials used were 45.0 parts by mass of hydrogenated m-xylylene diisocyanate, 20.0 parts by mass of 1,6-hexanediol, and 149.0 parts by mass of polyethylene glycol with a number average molecular weight of 2000, and no triethylamine was added. The polyethylene glycol content of polyurethane resin PU-2 was 54.7% by mass.

[0084] (Polymerization of polyurethane resin PU-3) As raw materials, 64.5 parts by mass of hydrogenated diphenylmethane diisocyanate, 21.5 parts by mass of dimethylolpropanoic acid, 11.2 parts by mass of neopentyl glycol, 150.5 parts by mass of polycarbonate diol of 1,6-hexanediol having a number average molecular weight of 2000, A polyurethane resin (PU-3) solution with a solids content of 35% by mass was prepared in the same manner as for polyurethane resin PU-1, except that 17.0 parts by mass of triethylamine was used. The acid value of polyurethane resin PU-3 was 36.2 mg KOH / g.

[0085] (Polyurethane resin PU-4) A 20% aqueous solution of a self-crosslinking polyurethane resin containing an isocyanate group blocked with sodium bisulfite (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name: Elastron H-3) was used as is. The acid value of the polyurethane resin PU-4 was 0.3 mg KOH / g.

[0086] (Polymerization of polyurethane resin PU-5) A four-neck flask equipped with a stirrer, Dimroth condenser, nitrogen inlet, silica gel drying tube, and thermometer was mixed with 100 parts by weight of a polyester diol (hydroxyl value: 2000 eq / t) consisting of adipic acid / 1,6-hexanediol / neopentyl glycol (molar ratio: 4 / / 2 / 3) and 41.4 parts by weight of xylylene diisocyanate. The mixture was reacted under a nitrogen stream at 80-90°C for 1 hour, then cooled to 60°C, and 70 parts by weight of tetrahydrofuran was added to dissolve the mixture, yielding a urethane prepolymer solution (NCO / OH ratio: 2.2, free isocyanate groups: 3.30% by weight). The urethane prepolymer solution was then heated to 40°C, and 45.5 parts by weight of a 20% by weight aqueous sodium bisulfite solution was added. The mixture was reacted at 40-50°C for 30 minutes with vigorous stirring. After confirming the disappearance of the isocyanate groups, the solution was diluted with water to obtain a self-crosslinking polyurethane resin (PU-5) solution containing isocyanate groups blocked with sodium bisulfite, with a solid content of 20% by mass. The acid value of the polyurethane resin PU-5 was 0.4 mg KOH / g.

[0087] (Polymerization of polyurethane resin PU-6) A polyurethane resin (PU-6) solution with a solids content of 35% by mass was prepared in the same manner as for polyurethane resin PU-1, except that the raw materials used were 82.8 parts by mass of hydrogenated m-xylylene diisocyanate, 25.0 parts by mass of dimethylolpropanoic acid, 21.0 parts by mass of 1,6-hexanediol, 150.0 parts by mass of a polyester diol consisting of adipic acid and 1,4-butanediol with a number average molecular weight of 2000, and 19.8 parts by mass of triethylamine. The acid value of polyurethane resin PU-6 was 37.7 mg KOH / g.

[0088] (Polymerization of polyurethane resin PU-7) A polyurethane resin (PU-7) solution with a solids content of 35% by mass was prepared in the same manner as for polyurethane resin PU-1, except that the raw materials used were 90.0 parts by mass of hydrogenated m-xylylene diisocyanate, 20.0 parts by mass of dimethylolpropanoic acid, 15.0 parts by mass of 1,6-hexanediol, 100.0 parts by mass of a polyester diol consisting of terephthalic acid and 3-methyl-1,5-pentanediol with a number average molecular weight of 500, and 15.8 parts by mass of triethylamine. The acid value of polyurethane resin PU-7 was 37.3 mg KOH / g.

[0089] (Polymerization of polyurethane resin PU-8) A polyurethane resin (PU-8) solution with a solids content of 35% by mass was prepared in the same manner as for polyurethane resin PU-1, except that the raw materials used were 39.4 parts by mass of hydrogenated m-xylylene diisocyanate, 15.0 parts by mass of 1,6-hexanediol, and 180.0 parts by mass of polyethylene glycol with a number average molecular weight of 2000, and no triethylamine was added. The polyethylene glycol content of polyurethane resin PU-8 was 76.8% by mass.

[0090] (Crosslinking agent) (Synthesis of crosslinker C-1) Into a flask equipped with a stirrer, a thermometer, and a reflux condenser, 66.6 parts by mass of a polyisocyanate compound having an isocyanurate structure made from hexamethylene diisocyanate (Duranate TPA, manufactured by Asahi Kasei Chemicals), 17.5 parts by mass of N-methylpyrrolidone, and 21.7 parts by mass of 3,5-dimethylpyrazole were added dropwise, and the mixture was maintained at 70°C for 1 hour under a nitrogen atmosphere. Then, 9.0 parts by mass of dimethylolpropanoic acid was added dropwise. The infrared spectrum of the reaction solution was measured, and after confirming that the absorption of the isocyanate group had disappeared, 6.3 parts by mass of N,N-dimethylethanolamine was added. After stirring for 1 hour, an appropriate amount of water was added to prepare a blocked isocyanate crosslinking agent (C-1) solution with a solid content of 40% by mass.

[0091] (Polymerization of crosslinker C-2) A flask equipped with a stirrer, thermometer, and reflux condenser was charged with 65.0 parts by weight of a polyisocyanate compound having an isocyanurate structure (Duranate TPA, manufactured by Asahi Kasei Chemicals Corporation), 17.5 parts by weight of N-methylpyrrolidone, 29.2 parts by weight of 3,5-dimethylpyrazole, and 21.9 parts by weight of polyethylene glycol monomethyl ether having a number average molecular weight of 500, and the mixture was maintained at 70 °C for 2 hours under a nitrogen atmosphere. Then, 4.0 parts by weight of trimethylolpropane was added dropwise. The infrared spectrum of the reaction solution was measured, and after confirming that the absorption of the isocyanate group had disappeared, 280.0 parts by weight of water was added. An appropriate amount of water was added to prepare a blocked polyisocyanate crosslinking agent (C-2) solution with a solids content of 40% by weight.

[0092] (Synthesis of crosslinker C-3) Into a flask equipped with a stirrer, a thermometer, and a reflux condenser, 66.6 parts by mass of a polyisocyanate compound having an isocyanurate structure made from hexamethylene diisocyanate (Duranate TPA, manufactured by Asahi Kasei Chemicals), 17.5 parts by mass of N-methylpyrrolidone, and 19.7 parts by mass of 2-butanone oxime were added dropwise, and the mixture was maintained at 70°C for 1 hour under a nitrogen atmosphere. Then, 9.0 parts by mass of dimethylolpropanoic acid was added dropwise. The infrared spectrum of the reaction solution was measured, and after confirming that the absorption of the isocyanate group had disappeared, 6.3 parts by mass of N,N-dimethylethanolamine was added. After stirring for 1 hour, an appropriate amount of water was added to prepare a blocked isocyanate crosslinking agent (C-3) solution with a solid content of 40% by mass.

[0093] (Synthesis of crosslinker C-4) A flask equipped with a stirrer, thermometer, and reflux condenser was charged with 150.0 parts by weight of water and 250.0 parts by weight of methoxypropyl alcohol and heated to 80°C under a nitrogen atmosphere. Subsequently, a monomer mixture consisting of 150.0 parts by weight of methyl methacrylate, 180.0 parts by weight of 2-isopropenyl-2-oxazoline, and 90.0 parts by weight of methoxypolyethylene glycol acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name: NK Ester AM-90G) and a polymerization initiator solution consisting of 18.0 parts by weight of 2,2'-azobis(2-amidinopropane) dihydrochloride as a polymerization initiator and 170.0 parts by weight of water were added dropwise from the dropping funnel over 2 hours under a nitrogen atmosphere while maintaining the flask at 80°C. After completion of the dropwise addition, the mixture was stirred at 80°C for 5 hours and then cooled to room temperature. An appropriate amount of water was added to prepare an oxazoline-based crosslinker (C-4) solution with a solids content of 40% by weight.

[0094] (polyester resin) (Synthesis of polyester resin PE-1) 95 parts by weight of dimethyl terephthalate, 95 parts by weight of dimethyl isophthalate, 35 parts by weight of ethylene glycol, 145 parts by weight of neopentyl glycol, 0.1 parts by weight of zinc acetate, and 0.1 parts by weight of antimony trioxide were charged into a reaction vessel and subjected to a transesterification reaction at 180°C for 3 hours. Next, 6.0 parts by weight of 5-sodium sulfoisophthalic acid was added, and an esterification reaction was performed at 240°C for 1 hour. After that, a polycondensation reaction was performed at 250°C under reduced pressure (1.33 to 0.027 kPa) for 2 hours to obtain a copolymer polyester resin (PE-1) with a number average molecular weight of 19,500 and a glass transition temperature of 62°C. 300 parts by mass of the obtained copolymer polyester resin (PE-1) and 140 parts by mass of butyl cellosolve were stirred at 160°C for 3 hours to obtain a viscous molten liquid, and water was gradually added to this molten liquid, and after 1 hour, a homogeneous, pale white polyester resin (PE-1) solution with a solids concentration of 15% was prepared.

[0095] (Polymerization of polyester resin PE-2) 97 parts by weight of dimethyl terephthalate, 93 parts by weight of dimethyl isophthalate, 68 parts by weight of ethylene glycol, 116 parts by weight of diethylene glycol, 0.1 parts by weight of zinc acetate, and 0.1 parts by weight of antimony trioxide were charged into a reaction vessel and subjected to a transesterification reaction at 180°C for 3 hours. Next, 7.1 parts by weight of 5-sodium sulfoisophthalic acid was added, and an esterification reaction was carried out at 240°C for 1 hour. After that, a polycondensation reaction was carried out at 250°C under reduced pressure (1.33 to 0.027 kPa) for 2 hours to obtain a polyester resin (PE-2) with a molecular weight of 22,000. 300 parts by weight of this polyester resin and 140 parts by weight of butyl cellosolve were stirred at 160°C for 3 hours to obtain a viscous molten solution. Water was gradually added to this molten solution, and after 1 hour, a homogeneous, pale white solution of polyester resin (PE-2) with a solids content of 15% by weight was prepared.

[0096] (Polymerization of polyester resin PE-3) A reactor was charged with 105 parts by weight of dimethyl 2,6-naphthalenedicarboxylate, 50 parts by weight of ethylene glycol, 36 parts by weight of hexanediol, 0.1 parts by weight of zinc acetate, and 0.1 parts by weight of antimony trioxide, and a transesterification reaction was carried out at 180°C for 3 hours. Next, 8.6 parts by weight of 5-sodium sulfoisophthalic acid and 8 parts by weight of sebacic acid were added, and an esterification reaction was carried out at 240°C for 1 hour. This was followed by a polycondensation reaction at 250°C under reduced pressure (1.33 to 0.027 kPa) for 2 hours to obtain a polyester resin (PE-3) with a molecular weight of 18,000. 300 parts by weight of this polyester resin (PE-3) and 140 parts by weight of butyl cellosolve were stirred at 160°C for 3 hours to obtain a viscous molten solution. Water was gradually added to this molten solution, and after 1 hour, a homogeneous, pale white polyester resin (PE-3) solution with a solids content of 15% by weight was prepared.

[0097] (particle) [Particle P-1] As the particles (P-1), colloidal silica (Snowtex XL; manufactured by Nissan Chemical Industries, Ltd.) having a solid content of 40% and an average particle size of 50 nm was used as it was as a particle (P-1) solution.

[0098] [Particle P-2] Particles (P-2) were prepared using fumed silica (Aerosil OX50; manufactured by Nippon Aerosil Co., Ltd.) with an average primary particle size of 40 nm. The particles were dispersed in water using an Ace Homogenizer AM-7 (manufactured by Nippon Seiki Seisakusho Co., Ltd.) at 10,000 rpm for 60 minutes to obtain a particle (P-2) solution with a solids concentration of 5.0%. The average particle size was measured to be 500 nm.

[0099] [Particle P-3] Fumed silica particles (Reolosil QS-09; Tokuyama Corp.) were used as the silica particles, and the dispersion medium was water. The particles were dispersed in an Ace Homogenizer AM-7 (Nippon Seiki Seisakusho Co., Ltd.) at 10,000 rpm for 60 minutes to obtain a particle (P-3) solution with a solids concentration of 5.0%. The average particle size was measured to be 300 nm.

[0100] [Particle P-4] Fumed aluminum oxide particles (AEROXIDE Alu65; manufactured by Nippon Aerosil Co., Ltd.) were dispersed in water using an Ace Homogenizer AM-7 (manufactured by Nippon Seiki Seisakusho Co., Ltd.) at 10,000 rpm for 60 minutes to obtain a particle (P-4) solution with a solids concentration of 5.0%. The average particle size was measured to be 400 nm.

[0101] [Particle P-5] To 10 g of colloidal silica (Snowtex 30L; manufactured by Nissan Chemical Industries, Ltd.) with a solids concentration of 30% and an average particle size of 45 nm was added 0.1 mol hydrochloric acid to adjust the pH of the solution to approximately 5. After leaving the solution to stand for 24 hours, it was diluted with water while stirring with a magnetic stirrer to obtain a particle (P-5) solution with a solids concentration of 5.0%. The average particle size of the aggregates was measured and found to be 200 nm.

[0102] [Particle P-6] Colloidal silica (MP2040; manufactured by Nissan Chemical Industries, Ltd.) having a solid content of 40% and an average particle size of 200 nm was used as the silica particles in the particle (P-6) solution.

[0103] [Particle P-7] Silica particles, Reolosil QS-09 (Tokuyama Corporation), were dispersed in an Ace Homogenizer AM-7 (Nihon Seiki Seisakusho Co., Ltd.) at 5000 rpm for 30 minutes to obtain 100 g of an aqueous dispersion with a solids concentration of 5.0%. This aqueous dispersion was then treated in an ultrasonic disperser (UH-600: SMT Corporation) at 600 W and 20 kHz for 10 minutes to obtain a particle (P-7) solution. The average particle size was measured to be 100 nm.

[0104] (Production of polyester resin E-1 for substrates) (Preparation of antimony trioxide solution) Antimony trioxide (Sigma-Aldrich Japan LLC) was placed in a flask together with ethylene glycol, stirred at 150°C for 4 hours to dissolve, and then cooled to room temperature to prepare a 20 g / L ethylene glycol solution of antimony trioxide.

[0105] (Polymerization of polyester resin E-1 for substrate) High-purity terephthalic acid and twice the molar amount of ethylene glycol were charged into a 2-liter stainless steel autoclave equipped with a stirrer, and 0.3 mol% triethylamine relative to the acid component was added. An esterification reaction was carried out at 250°C under a pressure of 0.25 MPa while distilling water out of the system, yielding a mixture of bis(2-hydroxyethyl) terephthalate and oligomers (hereinafter referred to as the BHET mixture) with an esterification rate of approximately 95%. The above antimony trioxide solution was added to the polyester so that the antimony atom concentration was 0.04 mol % relative to the acid component in the polyester, and the mixture was stirred for 10 minutes at 250°C under normal pressure in a nitrogen atmosphere. The temperature was then raised to 280°C over 60 minutes while the pressure of the reaction system was gradually reduced to 13.3 Pa (0.1 Torr), and the polycondensation reaction was carried out for a further 68 minutes at 280°C and 13.3 Pa to obtain a polyester resin E-1 having an intrinsic viscosity (IV) of 0.61 dL / s (solvent: phenol / tetrachloroethane = 60 / 40) and containing substantially no particles.

[0106] (Production of polyester resin E-2 for substrates) (Example of preparing an aluminum compound solution) A 20 g / L aqueous solution of basic aluminum acetate (hydroxyaluminum diacetate; manufactured by Sigma-Aldrich Japan LLC) was charged into a flask together with an equal volume (by volume) of ethylene glycol. The mixture was stirred at room temperature for 6 hours, and then the mixture was stirred under reduced pressure (133 Pa) at 70-90°C for several hours while distilling off water from the system, to prepare a 20 g / L ethylene glycol solution of the aluminum compound.

[0107] (Example of preparation of phosphorus compound solution) As a phosphorus compound, 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid diethyl ester (Irganox 1222 (BASF)) was charged into a flask together with ethylene glycol, and the mixture was heated at a liquid temperature of 160°C for 25 hours while stirring under nitrogen substitution to prepare a 50 g / L ethylene glycol solution of the phosphorus compound.

[0108] (Preparation of a mixture of an aluminum compound solution and a phosphorus compound solution) The ethylene glycol solutions obtained in the above aluminum compound preparation example and the above phosphorus compound preparation example were charged into a flask, mixed at room temperature so that the molar ratio of aluminum atoms to phosphorus atoms was 1:2, and stirred for one day to prepare a catalyst solution.

[0109] (Polymerization of polyester resin E-2 for substrate) Instead of antimony trioxide solution, a mixture of the above-mentioned aluminum compound solution and phosphorus compound solution was used as a polycondensation catalyst, so that the aluminum atoms and phosphorus atoms were 0.014 mol % and 0.028 mol %, respectively, relative to the acid component in the polyester. Polymerization was carried out in the same manner as for polyester resin E-1, except that the polymerization time was set to 68 minutes, thereby obtaining polyester resin E-2 having an intrinsic viscosity (IV) of 0.61 dL / and containing substantially no particles.

[0110] Example 1 (1) Preparation of coating solution The following coating agents were mixed with a mixed solvent of water and isopropanol (80 / 20 parts by mass) to prepare a coating solution such that the solids mass ratio of the polyurethane resin (PU-1) solution / polyester resin (PE-1) solution / crosslinker (C-1) solution was 25 / 45 / 30, and the solids mass ratios of the particle (P-2) solution and particle (P-1) solution were 0.5 and 8, respectively, relative to 100% solids of the resin and crosslinker. The blending ratios of the coating solutions are shown in Table 1. Mixed solvent (water / isopropanol) 65.65 parts by mass Polyurethane resin (PU-1) solution 5.00 parts by mass Polyester resin (PE-1) solution 21.00 parts by mass Crosslinking agent (C-1) solution 5.25 parts by mass Particle A Particle (P-2) solution 0.70 parts by mass particle B Particle (P-1) solution 1.40 parts by mass Surfactant 1.00 parts by mass (Silicone-based, solid content 10% by mass)

[0111] (2) Manufacturing of laminated polyester film Resin pellets of polyester resin E-1, used as the raw polymer for the film, were dried at 135°C for 6 hours under a reduced pressure of 133 Pa. Then, the resin pellets were fed into an extruder and melt-extruded into a sheet at approximately 280°C. The sheet was then rapidly cooled and solidified on a rotating cooling metal roll maintained at a surface temperature of 20°C to obtain an unstretched PET sheet.

[0112] This unstretched PET sheet was heated to 100° C. using a group of heated rolls and an infrared heater, and then stretched 3.5 times in the longitudinal direction using a group of rolls with different peripheral speeds to obtain a uniaxially stretched PET film.

[0113] Next, the coating solution was applied to one side of a PET film in an amount of 6.0 g / m 2 After drying, the coating solution was stretched 4.0 times in the width direction at 110°C, and then, with the film fixed in the width direction, heated at 230°C for 5 seconds. This was followed by a 3% relaxation treatment in the width direction to obtain a 100µm laminated polyester film. The evaluation results are shown in Table 2.

[0114] Example 2 The coating solution of Example 1 was changed as shown in Example 2 in Table 1, and the coating amount was 5.0 g / m 2 A laminated polyester film was obtained in the same manner as in Example 1, except that:

[0115] Example 3 A laminated polyester film was obtained in the same manner as in Example 1, except that the coating solution in Example 1 was changed as shown in Example 3 in Table 1.

[0116] Example 4 The coating solution of Example 1 was changed as shown in Example 4 in Table 1, and the coating amount was 8.0 g / m 2 A laminated polyester film was obtained in the same manner as in Example 1, except that:

[0117] Example 5 The coating solution of Example 1 was changed as shown in Example 5 in Table 1, and the coating amount was 4.0 g / m 2 A laminated polyester film was obtained in the same manner as in Example 1, except that:

[0118] Example 6 The coating solution of Example 1 was changed as shown in Example 6 in Table 1, and the coating amount was 7.0 g / m 2 A laminated polyester film was obtained in the same manner as in Example 1, except that:

[0119] Example 7 The coating solution of Example 1 was changed as shown in Example 7 in Table 1, and the coating amount was 5.0 g / m 2 A laminated polyester film was obtained in the same manner as in Example 1, except that:

[0120] Example 8 A laminated polyester film was obtained in the same manner as in Example 1, except that the coating solution in Example 1 was changed as shown in Example 8 in Table 1.

[0121] Example 9 For the coating solution of Example 1, the parts by mass of the mixed solvent were adjusted so that the total amount of the coating solution was 250 parts by mass, and the coating amount was further adjusted to 5.0 g / m 2 A laminated polyester film was obtained in the same manner as in Example 1, except that:

[0122] Example 10 A laminated polyester film was obtained in the same manner as in Example 1, except that the coating solution in Example 1 was changed as shown in Example 10 in Table 1.

[0123] Example 11 A laminated polyester film was obtained in the same manner as in Example 1, except that the coating solution in Example 1 was changed as described in Example 11 in Table 1 and resin pellets of polyester resin E-2 were used as the film raw material polymer.

[0124] (Comparative Example 1) A laminated polyester film was obtained in the same manner as in Example 1, except that the coating solution in Example 1 was changed as shown in Comparative Example 1 in Table 1.

[0125] (Comparative Example 2) A laminated polyester film was obtained in the same manner as in Example 1, except that the coating solution in Example 1 was changed as shown in Comparative Example 2 in Table 1.

[0126] (Comparative Example 3) In Example 1, the coating amount was 5.0 g / m 2 A laminated polyester film was obtained in the same manner as in Example 1, except that the film was stretched 2.5 times in the width direction.

[0127] Comparative Example 4 The coating solution of Example 1 was changed as shown in Comparative Example 4 in Table 1, and the coating amount was 5.0 g / m 2 A laminated polyester film was obtained in the same manner as in Example 1, except that:

[0128] (Comparative Example 5) The coating solution of Example 1 was changed as shown in Comparative Example 5 in Table 1, and the coating amount was 8.0 g / m 2 A laminated polyester film was obtained in the same manner as in Example 1, except that:

[0129] (Comparative Example 6) The coating solution of Example 1 was changed as shown in Comparative Example 6 in Table 1, and the coating amount was 4.0 g / m 2A laminated polyester film was obtained in the same manner as in Example 1, except that:

[0130] (Comparative Example 7) The parts by mass of the mixed solvent were adjusted so that the total amount of the coating solution was 1,000 parts by mass, and the coating solution of Example 1 was changed as shown in Comparative Example 7 in Table 1, and the coating amount was 2.0 g / m 2 A laminated polyester film was obtained in the same manner as in Example 1, except that:

[0131] (Comparative Example 8) A laminated polyester film was obtained in the same manner as in Example 1, except that the coating solution in Example 1 was changed as shown in Comparative Example 8 in Table 1.

[0132] (Comparative Example 9) A laminated polyester film was obtained in the same manner as in Example 1, except that the coating solution in Example 1 was changed as shown in Comparative Example 9 in Table 1.

[0133] (Comparative Example 10) The coating solution of Example 1 was changed as shown in Comparative Example 10 in Table 1, and the coating amount was 5.5 g / m 2 A laminated polyester film was obtained in the same manner as in Example 1, except that:

[0134] Table 2 summarizes the evaluation results for each example and comparative example.

[0135] As shown in Table 2, in each Example, satisfactory results were obtained in terms of haze, blocking resistance, adhesion to UV ink, adhesion to the hard coat layer, etc. On the other hand, in each Comparative Example, satisfactory results were not obtained in any of the evaluation items.

[0136] [Table 1]

[0137] [Table 2] [Industrial Applicability]

[0138] According to the present invention, it is possible to provide a laminated polyester film that can be suitably used in a variety of fields, including optical applications, packaging applications, and label applications.

Claims

1. A polyester film has a coating layer formed on at least one surface thereof from a coating liquid containing a polyurethane resin, a polyester resin, a crosslinking agent, and particles, and satisfies the following (1) to (4): The particles include aggregates of metal oxide fine particles, The average particle size of the aggregates is in the range of 80 to 600 nm. Laminated polyester film; (1) Coating thickness (d) is 0.03 μm or more and 1.0 μm or less (2) On the surface of the coating layer, there are particles having a height of 0.01 to 0.50 μm and a minor axis / major axis ratio of 6 protrusions / mm with a thickness of 0.2 to 0.5 ２ End (3) The ratio (V / d) of the maximum depression depth (V) on the coating layer surface to the coating thickness (d) is less than 0.

6. (4) The haze of the laminated polyester film is 2.0% or less.

2. The laminated polyester film according to claim 1 , wherein the aggregates contained in the particles of the coating layer comprise aggregates of fumed metal oxide particles.

3. the cross-linking agent of the coating layer is a blocked isocyanate compound, The laminated polyester film is a laminated polyester film formed by applying a coating liquid to at least one surface of an unstretched or uniaxially stretched PET film, and then stretching the film 3.0 to 5.0 times. The laminated polyester film according to claim 1 or 2.

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