Laminated polyester film

Abstract

To stably provide a laminated polyester film reduced in the flaw of a coating film such as coating irregularity at the time of production and excellent in the transparency or adhesiveness of the coating film.SOLUTION: In the method for manufacturing the laminated film having a coating layer on at least one surface of a polyester film base material, the coating layer is formed of a composition containing at least one or more kinds of resins having a carboxyl group selected from a polyester resin, a polyurethane resin and an acrylic resin, and two kinds of amine compounds having a boiling point of 60 °C or higher. In which a difference in boiling point between the two kinds of amine compounds is 40 °C or higher, the two kinds of amine compounds are an amine compound (A) having a high boiling point and an amine compound (B) having a low boiling point, and in a step of preparing the water dispersion of the resin having a carboxyl group, both the amine compound (A) having a high boiling point and the amine compound (B) having a low boiling point are added.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a laminated polyester film, and more particularly to a laminated polyester film having an easily adhesive coating layer that is optimal for all fields such as optical applications, packaging applications, and labels. [Background technology]

[0002] Thermoplastic resin films, especially polyester films, have excellent mechanical properties, electrical properties, dimensional stability, transparency, chemical resistance, etc., and are therefore widely used in magnetic recording materials, packaging materials, solar cell applications, optical films such as anti-reflection films used in flat displays, diffusion sheets, prism sheets, etc., and films for label printing, etc. However, because polyester films have a highly crystalline orientation on the surface, they have the drawback of poor adhesion to various paints, resins, UV-curable resins, inks, etc. when processed for these applications.

[0003] For this reason, various methods have been studied to impart adhesiveness to the surface of polyester film. A well-known method involves applying an aqueous dispersion of a resin having a hydrophilic group such as a sulfonic acid group to the surface of the polyester film to form a coating layer with high adhesive properties (see Patent Document 1). Furthermore, maintaining adhesiveness even in high-temperature, high-humidity environments (moist heat resistance) is required, and for this reason, the use of a carboxyl group salt as the hydrophilic group of the resin instead of the sulfonic acid group has been studied (see Patent Documents 2 to 4). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 58-78761 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-125599 [Patent Document 3] Japanese Patent Publication No. 2020-016872 [Patent Document 4] Japanese Patent Application Laid-Open Publication No. WO2015 / 098750 Summary of the Invention [Problem to be solved by the invention]

[0005] Since laminated polyester films are used in a variety of applications and in a variety of environments, there has been an increasing demand in recent years for the aforementioned moist heat resistance and also for high quality. However, conventional laminated polyester films have not satisfied the market in terms of moist heat resistance and quality.

[0006] The present invention was made in response to the problems of the prior art. Specifically, an object of the present invention is to stably provide a laminated polyester film that has few coating defects, such as coating spots, during production and has excellent coating transparency or adhesion. Furthermore, the laminated polyester film of the present invention is characterized by its excellent adhesion to various paints, resins, UV-curable resins, inks, etc., particularly excellent adhesion to UV-curable resins, and by its ability to maintain a high level of adhesion over a long period of time. [Means for solving the problem]

[0007] In the course of investigating the above-mentioned problems, the present inventors discovered that the behavior of the hydrophilicity change during heating and drying of a coating liquid varies depending on the type or amount of the base component paired with the carboxyl group, which is the carboxyl group salt used as the hydrophilic group of the resin, and this causes defects such as coating spots due to uneven heating temperature or air volume distribution during production, and deterioration of performance such as transparency and adhesion of the coating film.As a countermeasure, the present inventors discovered that the problems of the present invention can be solved by preparing a coating layer mainly from at least one carboxyl group-containing resin selected from polyester resin, polyurethane resin, and acrylic resin, and a specific amine compound, and thus completed the present invention.

[0008] That is, the present invention comprises the following: (1) A laminated polyester film having a coating layer on at least one surface of a polyester film substrate, the coating layer being formed from a composition containing at least one resin having a carboxyl group selected from polyester resins, polyurethane resins, and acrylic resins, and two amine compounds having a boiling point of 60°C or higher, the difference in boiling points between the two amine compounds being 40°C or higher. (2) The laminated polyester film according to (1), wherein at least one of the two amine compounds has a boiling point of 110° C. or higher. (3) The laminated polyester film according to (1) or (2), wherein the acid value of the resin having a carboxyl group is in the range of 10 to 60 mgKOH / g. [Effects of the Invention]

[0009] The laminated polyester film of the present invention has few coating defects and is excellent in coating transparency and adhesion, and is therefore suitably used as a substrate film for UV-curable resins such as hard coat films for optical or building materials, or for UV-curable inks such as printing films. DETAILED DESCRIPTION OF THE INVENTION

[0010] (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.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] (coating layer) In order to reduce coating defects and improve the transparency and adhesion of the coating, the laminated polyester film of the present invention preferably has a coating layer laminated on at least one side thereof, the coating layer being formed from a composition containing at least one resin having a carboxyl group selected from polyester resins, polyurethane resins, and acrylic resins, and two amine compounds having a boiling point of 60° C. or higher and a boiling point difference of 40° C. or higher. The coating layer may be formed on both sides of the polyester film, or, depending on the application, may be formed on only one side of the polyester film, with a coating layer of a different resin being formed on the other side.

[0015] The carboxyl groups of the resin used in the coating layer form salts with amine compounds, improving hydrophilicity. As a result, the resin can exist stably as an emulsion in an aqueous solvent. Furthermore, by heating, such as during drying of the coating liquid, the amine compounds with relatively low boiling points are released and volatilized from the carboxyl salts, regenerating the less hydrophilic carboxyl groups, thereby improving the wet heat resistance of the coating film after formation. However, when using only amine compounds with relatively low boiling points, the volatilization of the amine compounds themselves occurs faster than the evaporation of the aqueous solvent during the coating liquid drying process. This reduces the hydrophilicity of the resin in the coating liquid during drying, making the emulsion unstable and prone to coating film irregularities or defects such as aggregation. Conversely, when using only amine compounds with high boiling points, the resin retains the highly hydrophilic carboxyl salts even after drying of the aqueous solvent, which can reduce the moisture resistance or water resistance of the coating film itself. Furthermore, it is preferable that the amine compounds used in the present invention have a relatively high boiling point. A relatively high boiling point is preferable because it makes it less likely for the amine compounds to volatilize at low temperatures during the coating film drying process.

[0016] As a result of this study, the aforementioned problems can be solved by forming a coating layer from a composition containing two amine compounds, each with a boiling point of 60°C or higher and a boiling point difference of 40°C or more, as amine compounds paired with a carboxyl group. Specifically, when the amine compound with the lower boiling point volatilizes first, the amine compound with the higher boiling point remains with the carboxyl group salt, maintaining the stability of the resin emulsion. Therefore, even if the drying speed of the coating solution changes due to fluctuations in heating temperature or air volume or distribution in the surface direction, emulsion aggregation is suppressed, resulting in reduced occurrence of spots or defects in the coating film. Furthermore, in the dried coating film, the volatilization of the amine compound with the lower boiling point reduces the proportion of carboxyl group salt in the resin, thereby preventing a decrease in the moisture or water resistance of the coating film itself.

[0017] (amine compounds) In the present invention, the difference in boiling points between the two amine compounds contained in the composition, each having a boiling point of 60°C or higher, is preferably 40°C or higher. Furthermore, the boiling point of at least one of the two amine compounds is preferably 110°C or higher, more preferably 120°C or higher, and particularly preferably 130°C or higher. In the present invention, if the amine compound has a sufficiently high boiling point and a low decomposition temperature, this decomposition temperature can be used as an indicator of the boiling point in the present invention. When the amine compound used in the present invention has a boiling point of 110°C or higher, it does not evaporate faster than the water solvent during the coating drying process, and the amount of carboxyl group salt in the resin increases, stabilizing the resin emulsion and suppressing coating film mottles or defects, which is preferable. There is no particular upper limit for the boiling point of the amine compound other than the decomposition temperature. However, when both boiling points of the two amine compounds are 110°C or higher, it is preferable that the boiling point of at least one amine compound be 140°C or lower, from the viewpoint of the coating drying process.

[0018] As the amine compound that can be used in the present invention, a compound containing a nitrogen atom can be used as long as it has a boiling point of 60°C or higher. However, azides are preferably not used in the present invention because they are unstable to heat, etc. Examples of amine compounds with a boiling point of 60°C or higher include aliphatic monoamine compounds such as primary amines such as butylamine (boiling point 78°C), isobutylamine (boiling point 68-69°C), pentylamine (boiling point 104.4°C), hexylamine (boiling point 131-132°C), heptylamine (boiling point 154-156°C), octylamine (boiling point 175-177°C), cyclohexylamine (boiling point 134.5°C), and allylamine (boiling point 96-98°C). amine, dipropylamine (boiling point 105-110°C), diisopropylamine (boiling point 84°C), dibutylamine (boiling point 159°C), diisobutylamine (boiling point 137-139°C), dipentylamine (boiling point 203°C), dihexylamine (boiling point 236°C), dioctylamine (boiling point 297-298°C), dicyclohexylamine (boiling point 134.5°C), diallylamine (boiling point 111-112°C), ethylpropylamine ( Secondary amines such as methylbutylamine (boiling point 91°C), N-methyldiethylamine (boiling point 62°C), triethylamine (boiling point 89°C), tripropylamine (boiling point 155-158°C), N,N-dipropylethylamine (boiling point 132°C), tributylamine (boiling point 217°C), triisobutylamine (boiling point 192-193°C), tripentylamine (boiling point 240°C), trihexylamine (boiling point 150- 159°C), triheptylamine (boiling point 153°C), trioctylamine (365 to 367°C), tricyclohexylamine (boiling point 134.5°C), triallylamine (boiling point 156°C), N,N-diethylpropylamine, N-butyldimethylamine (boiling point 93°C), N,N-diisopropylethylamine (boiling point 127°C), N-methyl-N-ethylpropylamine (boiling point 91.5°C), etc.

[0019] Alicyclic monoamine compounds include pyrrolidine (boiling point 87°C), piperidine (boiling point 106°C), 2-azabicyclo[2.2.1]heptane (boiling point 135°C), N-methylpyrrolidine (boiling point 76-80°C), N-methylpiperidine (boiling point 107°C), 2-methyl-2-azabicyclo[2.2.1]heptane (boiling point 198°C), quinuclidine (boiling point 198.35°C), etc. Aromatic amines include aniline (boiling point 184.13°C), N-methylaniline (boiling point 196°C), N,N-dimethylaniline (boiling point 193°C), and N,N-diethyl-1-naphthylamine (boiling point 285°C). Examples of heterocyclic amine compounds include pyrrole (boiling point 129 to 131°C), pyridine (boiling point 115.2°C), quinoline (boiling point 238°C), isoquinoline (boiling point 242°C), acridine (boiling point 346°C), etc. Examples of compounds containing atoms other than carbon and hydrogen atoms include dimethylethanolamine (boiling point 134°C), dimethylaminomethanol (boiling point 88°C), monoethanolamine (boiling point 170°C), diethanolamine (boiling point 217°C), triethanolamine (boiling point 335°C), N-methyldiethylamine (boiling point 62°C), morpholine (boiling point 129°C), oxazole (boiling point 69 to 70°C), thiomorpholine (boiling point 166.87°C), and thiazine (boiling point 76 to 77°C). Compounds having multiple nitrogen atoms in the molecule include ethylenediamine (boiling point 117°C), N,N,N',N'-tetraethylethylenediamine (boiling point 189 to 192°C), N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine (boiling point 175 to 181°C), piperazine (boiling point 144°C), piperazine (boiling point 146°C), triazine (boiling point 114°C), imidazole (boiling point 256°C), and 2-methylimidazole. (boiling point 267 to 268°C), 1-(2-aminoethyl)-2-methylimidazole (boiling point 273.6°C ± 23.0°C), and hydrazides such as oxalic acid dihydrazide (boiling point 220.6°C), malonic acid dihydrazide (boiling point 554.0°C ± 33.0°C), succinic acid dihydrazide (boiling point 540.2°C ± 33.0°C), adipic acid dihydrazide (boiling point 305.18°C), and terephthalic acid dihydrazide (melting point exceeding 300°C).

[0020] In the present invention, a monoamine compound having only one nitrogen atom in the molecule is preferred because the amine compound pairs with a carboxyl group to form a salt. Furthermore, from the viewpoint of preventing discoloration due to oxidation of the amino group, etc., a secondary amine is preferred over a primary amine or an aromatic amine, and a tertiary amine is more preferred.

[0021] The amine compound in the present invention may have a functional group other than a nitrogen-based functional group, and examples of such functional groups include a carboxyl group, a hydroxyl group, an ether group such as a methoxy group, etc. In the present invention, from the viewpoint that the carboxyl group salt imparts water dispersibility to the resin, an amine compound containing a highly hydrophilic ether group such as a hydroxyl group or a methoxy group, which further improves water dispersibility, etc., is more preferred.

[0022] In the present invention, an amine compound with a boiling point of 60°C or higher is used, but if the amount is small due to impurities in the amine compound or contamination from other additives, there is no problem in using an amine compound with a boiling point of less than 60°C, such as ammonia, or an inorganic salt of an alkali metal element such as sodium, or an alkaline earth metal element such as magnesium. The upper limit of the amount used cannot be determined in general depending on the type and concentration of the coating material, but if it is about 10% by mass of the total amount of the amine compound in the present invention, it can be used without any particular problem.

[0023] In the present invention, two types of amine compounds are used, and the abundance ratio (A / B: molar ratio) of the amine compound (A) having a higher boiling point to the amine compound (B) having a lower boiling point is preferably 0.5 to 5.0, more preferably 0.6 to 4.5, and particularly preferably 0.7 to 3.5. An abundance ratio of 0.5 or more is preferred from the viewpoint of suppressing the occurrence of coating defects or coating unevenness, and an abundance ratio of 5.0 or less is preferred from the viewpoint of the moist heat resistance of the coating film.

[0024] The amine compound in the present invention is preferably used to neutralize the carboxyl groups of the resin, but the amine compound itself may also be added separately to the coating liquid. In this case, it is preferable that the amine compound (A) has a high boiling point. This is because an amine compound (B) with a low boiling point volatilizes in a large amount from the coating liquid, which is undesirable from the viewpoint of the stability of the coating liquid composition or the working environment.

[0025] The content of the two amine compounds is preferably in the range of 0.5 to 5.0, more preferably 0.6 to 4.5, and particularly preferably 0.7 to 4.0, in terms of molar ratio relative to the amount of carboxyl groups in the resin in the composition.

[0026] If the molar ratio is 0.5 or more, the amount of salt formed by the carboxyl groups in the resin becomes appropriate, improving the water dispersibility of the resin and improving the stability of the emulsion. Also, if the molar ratio is 5.0 or less, the amount of amine compound remaining after forming the coating film is reduced, which is preferable from the viewpoint of moist heat resistance.

[0027] The above is a molar ratio, but when the molecular weight is not clear, for example, in the case of an amine compound derived from a natural fat or oil component, it is also possible to use the amine value instead of the mole as an index.

[0028] In the present invention, the difference in boiling points between the two amine compounds contained in the composition is preferably 40°C or more. However, similar to the above-mentioned amine compounds with boiling points of less than 60°C, there is no particular problem even if amine compounds other than the two used, which have boiling points of 60°C or higher, are mixed in, as long as the amount is small.

[0029] In the present invention, the molar ratio (A / B) of the high-boiling-point amine compound (A) to the low-boiling-point amine compound (B) is not particularly limited. However, the amount of amine compounds decreases during the drying process of the coating liquid, and the amount of the low-boiling-point amine compound (B) decreases more than the amount of the high-boiling-point amine compound (A). Therefore, the ratio of these amine compounds after drying and film formation is likely to change. However, since even small amounts of the amine compounds used remain in the coating film, these amine compounds can be identified. Furthermore, the amount of amine compounds remaining in the coating film depends on the boiling point of the amine compound itself and the drying conditions. For these reasons, the ratio of these amine compounds in the coating liquid can be calculated from the ratio of these amine compounds remaining in the coating film.

[0030] (Polyester resin having carboxyl groups) Polyester resins can usually be obtained from dicarboxylic acids and diols. Examples of dicarboxylic acids include aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, trimethyladipic acid, pimelic acid, 2,2-dimethylglutaric acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, and itaconic acid; aromatic dicarboxylic acids such as naphthalenedicarboxylic acids (e.g., phthalic acid, terephthalic acid, isophthalic acid, benzylmalonic acid, diphenic acid, 4,4'-oxydibenzoic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid); and alicyclic dicarboxylic acids such as 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and 2,5-norbornanedicarboxylic acid. Examples of trivalent or higher polycarboxylic acids include trimellitic acid, pyromellitic acid, adamantanetricarboxylic acid, and trimesic acid. These may be used alone or in combination of two or more.

[0031] Examples of diols include linear aliphatic diols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 1,9-nonanediol; branched aliphatic diols such as propylene glycol, dipropylene glycol, 2,4-dimethyl-2-ethylhexane-1,3-diol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 1,3-butanediol, 3-methyl-1,5-pentanediol, and 2,2,4-trimethyl-1,6-hexanediol; Alicyclic diols such as 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, spiroglycol, and tricyclodecane dimethanol; Aromatic diols such as 4,4'-methylenediphenol, bisphenol S, bisphenol A, bisphenol fluorene, 4,4'-dihydroxybiphenyl, 2,5-naphthalenediol, and p-xylenediol, or ethylene oxide or propylene oxide adducts thereof, Examples of trihydric or higher polyols include pentaerythritol, dipentaerythritol, tripentaerythritol, glycerin, trimethylolpropane, trimethylolethane, etc. These may be used alone or in combination of two or more.

[0032] The polyester resin having carboxyl groups of the present invention can be easily obtained by incorporating an excess of the aforementioned dicarboxylic acid. However, in this case, the carboxyl groups are introduced to the molecular terminals, and simply increasing the amount of carboxyl groups introduced results in a small molecular weight. To avoid this, a branched structure can be formed by using an appropriate amount of a tri- or higher functional polycarboxylic acid or polyol. However, in the present invention, it is preferable to introduce carboxyl groups into the molecule by reacting hydroxyl groups in the polyester molecule with a polycarboxylic acid anhydride.

[0033] The polycarboxylic acid anhydride is a compound having at least three or more carboxyl groups for the purpose of introducing carboxyl groups, and these carboxyl groups have at least one carboxylic acid anhydride structure. Examples include trimellitic anhydride, cyclohexane-1,2,4-tricarboxylic acid 1,2-anhydride, pyromellitic anhydride, 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride, 4,4-oxydiphthalic acid dianhydride, 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, cyclopentanetetracarboxylic acid dianhydride, ethylenetetracarboxylic acid dianhydride, and 1,2,3,4-butanetetracarboxylic acid dianhydride. These may be used alone or in combination of two or more.

[0034] The carboxyl group-containing polyester resin of the present invention preferably has an acid value in the range of 10 to 60 mgKOH / g, more preferably 15 to 50 mgKOH / g. An acid value of 10 mgKOH / g or more is preferred from the viewpoint of suppressing the occurrence of coating defects or coating unevenness, which is an effect of the present invention, and an acid value of 60 mgKOH / g or less is preferred from the viewpoint of moist heat resistance.

[0035] It is also preferred that 50 mol % or more of these carboxyl groups form salts with the above-mentioned amine compounds. When the amount of salt formed among the carboxyl groups is 50 mol % or more, the hydrophilicity of the polyester resin is improved, thereby improving the stability of the emulsion.

[0036] The polyester resin having a carboxyl group in the present invention has an amine salt of a carboxyl group as a hydrophilic group, but other hydrophilic groups may be introduced as long as the effects of the present invention are not impaired. Examples of such groups include sodium or potassium salts of a carboxyl group, a sulfonic acid group, a phosphonic acid group, a hydroxyl group, and an ether group.

[0037] (Polyurethane resin with carboxyl groups) A carboxyl group-containing polyurethane resin is a urethane resin derived from at least a polyol component, a polyisocyanate component, and optionally a chain extender, and has a carboxyl group in the molecule or on a side chain. "In the molecule" here refers to a group present in the main chain or at the terminal of the polyurethane resin. Furthermore, a side chain refers to a group introduced into a branched molecular chain after synthesis and polymerization by the presence of three or more terminal functional groups in any of the raw material components constituting the molecular chain. The polyurethane resin having a carboxyl group in the present invention can be preferably obtained by using a carboxyl group-containing polyol component as the main urethane component.

[0038] 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. 2,2-dimethylolpropionic acid and 2,2-dimethylolbutanoic acid are particularly suitable for introducing carboxyl groups.

[0039] The carboxyl group-containing polyurethane preferably has an acid value in the range of 10 to 60 mgKOH / g, more preferably 15 to 50 mgKOH / g. An acid value of 10 mgKOH / g or more is preferred from the viewpoint of suppressing the occurrence of coating defects or coating unevenness, which is an effect of the present invention, and an acid value of 60 mgKOH / g or less is preferred from the viewpoint of moist heat resistance. However, other hydrophilic groups, such as hydroxyl groups, ethers, sulfonic acids, phosphonic acids, etc., may be introduced to improve the water solubility or water dispersibility of the polyurethane resin, as long as the effect of the present invention is not impaired.

[0040] It is also preferred that 50 mol % or more of the carboxyl groups in these polyurethanes form salts with the aforementioned amine compounds. When the amount of salt formed of the carboxyl groups is 50 mol % or more, the hydrophilicity of the polyurethane resin is improved, thereby improving the stability of the emulsion.

[0041] The other polyol component used for synthesizing and polymerizing the polyurethane resin of the present invention preferably contains an aliphatic polycarbonate polyol, which has excellent heat resistance and hydrolysis resistance. Examples of the aliphatic polycarbonate polyol include an aliphatic polycarbonate diol and an aliphatic polycarbonate triol, and the 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.

[0042] The number average molecular weight of the 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 3000 or less, blocking resistance can be improved, which is preferable.

[0043] Examples of polyisocyanates used in the synthesis and polymerization of the urethane resin in the present invention include aromatic aliphatic diisocyanates such as 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, as well as modified polyisocyanates containing isocyanurate bonds, biuret bonds, or allophanate bonds produced from diisocyanates, and polyisocyanates in which one or more diisocyanates are pre-added with trimethylolpropane or the like. The use of the aromatic aliphatic diisocyanates, alicyclic diisocyanates, or aliphatic diisocyanates described above is preferred because they do not cause yellowing problems.

[0044] 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, thiodiglycols such as thiodiethylene glycol, and water. Furthermore, small amounts of polyols and polyamines having three or more functional groups may also be used.

[0045] 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.

[0046] (acrylic resin with carboxyl groups) The acrylic resin having a carboxyl group in the present invention is a copolymer formed primarily from acrylic acid, methacrylic acid, or their esters. Various compounds can be used as the acrylic acid or methacrylic acid ester. For example, acrylic acid esters such as methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-amyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, decyl acrylate, dodecyl acrylate, cyclohexyl acrylate, isobornyl acrylate, and stearyl acrylate can be used as the methacrylic acid ester, replacing the acrylic acid with methacrylic acid.

[0047] Further examples of the compound include acrylic acid esters or methacrylic acid esters into which a hydroxyl group, an ether group, a sulfonic acid group, or the like has been introduced, acrylic acid or methacrylic acid amide, nitriles such as acrylonitrile or methacrylonitrile, styrenes such as styrene and α-methylstyrene, vinyls such as vinyl acetate and vinyl propionate, and allyls such as allyl acetate and allyl propionate, as long as the effect of the present invention is not impaired.

[0048] The acrylic resin having a carboxyl group of the present invention preferably has an acid value in the range of 10 to 60 mgKOH / g, more preferably 15 to 50 mgKOH / g. An acid value of 10 mgKOH / g or more is preferred from the viewpoint of suppressing the occurrence of coating defects or coating unevenness, which is an effect of the present invention, and an acid value of 60 mgKOH / g or less is preferred from the viewpoint of moist heat resistance.

[0049] The carboxyl group of the acrylic resin can be imparted by using acrylic acid or methacrylic acid, but unsaturated carboxylic acids such as maleic acid and itaconic acid can also be used in the same way.

[0050] It is preferable that 50 mol % or more of the carboxyl groups of the acrylic resin form salts with the above-mentioned amine compounds. When the amount of salts of the carboxyl groups is 50 mol % or more, the hydrophilicity of the acrylic resin is good and the stability of the emulsion is increased, which is preferable.

[0051] In the coating layer of the present invention, other resins may be used in combination with the above-mentioned polyester resin, polyurethane resin, and acrylic resin, such as polyester resins, polyurethane resins, and acrylic resins that do not have a carboxyl group other than those mentioned above, as well as vinyl acetate, polyvinyl alcohol, and hydroxycellulose.

[0052] (Crosslinking agent) In the present invention, it is desirable to use a crosslinking agent in combination with the resin described above in the coating layer. The use of a crosslinking agent in combination can further improve the wet heat resistance of the coating layer. The type of crosslinking agent is not particularly limited, and those used in water-based coating materials, such as isocyanate-based, oxazoline-based, carbodiimide-based, epoxy-based, and melamine-based crosslinkers, can be used. Among these, oxazoline-based and carbodiimide-based crosslinkers are preferred, as they are expected to improve crosslink density by reacting with the carboxyl group of the resin. Furthermore, isocyanate-based crosslinkers are also preferred because they can relatively easily introduce polyester skeletons, polyurethane skeletons, etc. into the molecule, allowing for adjustment of compatibility with the aforementioned resins, etc. Furthermore, among isocyanate-based crosslinkers, blocked isocyanate-based crosslinkers are particularly preferred, as they allow adjustment of the crosslinking initiation temperature depending on the type of blocking agent.

[0053] The amount of crosslinking agent used is preferably less than 50% by mass of the total amount of the resin and crosslinking agent. If the amount of crosslinking agent is less than 50% by mass, the resin content becomes relatively high, which is preferable from the viewpoint of UV ink adhesion, etc. The amount of crosslinking agent is more preferably 45% by mass or less, and particularly preferably 40% by mass or less.

[0054] (additives) The coating layer of the present invention may contain known additives, such as surfactants, antioxidants, heat stabilizers, weather stabilizers, ultraviolet absorbers, organic or inorganic lubricants, pigments, dyes, organic or inorganic particles, and antistatic agents, within the range that does not impair the effects of the present invention.

[0055] In the present invention, it is also a preferred embodiment to add particles to the coating layer in order to further improve the blocking resistance of 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 other general inorganic particles such as calcium phosphate, mica, hectorite, zirconia, tungsten oxide, lithium fluoride, calcium fluoride, etc., used in combination with other inorganic particles, and organic polymer particles such as styrene-based, acrylic-based, melamine-based, benzoguanamine-based, and silicone-based particles.

[0056] In the present invention, two amine compounds with a boiling point of 60°C or higher and a boiling point difference of 40°C or higher are used, so the pH of the coating liquid is high, and even during the coating liquid drying process, the presence of the amine compound with a relatively high boiling point suppresses pH fluctuations, making it possible to suppress aggregation of dispersed particles in the coating liquid due to pH fluctuations.For this reason, it is particularly preferable to use particles whose aqueous dispersion is stable in the basic pH range.However, as long as aggregation of particles in the coating liquid can be suppressed by a dispersant, surface treatment agent, or the like, this does not limit the use of particles whose aqueous dispersion is unstable in the basic pH range.

[0057] In addition, in the present invention, in order to prevent the particles from agglomerating, the particles to be used can be pretreated with the resin having a carboxyl group of the present invention. There are no particular restrictions on the resin to be used, but acrylic resin is preferred in terms of resin design or treatment conditions. Examples of treatment include a method in which particles and resin are premixed in an organic solvent and then dispersed in water, a method in which resin is mixed with water-dispersed particles, and a method in which particles and monomers are premixed and then polymerized.

[0058] The average particle size of the particles in the coating layer (average particle size based on the number of particles as measured by a scanning electron microscope (SEM); the same applies hereinafter) is preferably 0.04 to 2.0 μm, more preferably 0.1 to 1.0 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 improves the handling properties of the film, such as its slipperiness and winding ability, and improves the processability during lamination, which is preferable. On the other hand, when the average particle size of the inactive particles is 2.0 μm or less, it is preferable that the particles are less likely to fall off. The particle concentration in the coating layer is preferably 1 to 20 mass % of the solid components.

[0059] The average particle size of the particles was measured by observing the 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.

[0060] The shape of the 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 the value obtained by dividing the observed particle area by π, calculating the square root, and then multiplying it by two.

[0061] (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.

[0062] After thorough vacuum drying, the PET resin is fed to an extruder, and the molten PET resin at about 280°C is extruded from a T-die onto a rotating cooling roll in the form of a sheet, which is then cooled and solidified by electrostatic application to obtain an unstretched PET sheet. The unstretched PET sheet may have a single layer structure or a multilayer structure formed by coextrusion.

[0063] 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 2.5 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 2.5 to 5.0 times in the width direction. In the case of uniaxial stretching, the film is stretched 2.5 to 5.0 times in a tenter. After stretching, the film is subsequently introduced into a heat treatment zone where it is heat-treated to complete the crystal orientation.

[0064] The lower limit of the temperature in the heat treatment zone is preferably 170°C, more preferably 180°C. When the temperature in the heat treatment zone is 170°C or higher, sufficient curing is achieved, blocking resistance in a high humidity environment is favorable, and adjustment of the storage environment, etc. is easy, which is also favorable. On the other hand, the upper limit of the temperature in the heat treatment zone is preferably 260°C, more preferably 250°C. When the temperature in the heat treatment zone is 250°C or lower, there is no risk of deterioration in the physical properties of the film, which is favorable.

[0065] The coating layer can be provided after or during the film production process. From the viewpoint of productivity, it is particularly preferred to form the coating layer by applying a coating liquid to at least one surface of an unstretched or uniaxially stretched PET film at any stage of the film production process.

[0066] Any known method can be used to apply this 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.

[0067] In the present invention, the thickness of the coating layer can be appropriately set within the range of 0.001 to 2.00 μm, but in order to achieve both processability and adhesiveness, it is preferably within the range of 0.01 to 1.00 μm, more preferably 0.02 to 0.80 μm, and even more preferably 0.05 to 0.50 μm. A coating layer thickness of 0.001 μm or more is preferable because it provides good adhesiveness. A coating layer thickness of 2.00 μm or less is preferable because it is less likely to cause blocking.

[0068] The upper limit of the haze of the laminated polyester film of the present invention is preferably 2.5%, more preferably 2.0%, even more preferably 1.5%, and particularly preferably 1.2%. A haze of 2.5% or less is preferable in terms of transparency, and the film can be suitably used in optical films that require transparency. The lower the haze, the better, but a haze of 0.1% or more is also preferable, and even 0.3% or more is also preferable. [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) Hayes The haze of the obtained laminated polyester film was measured in accordance with JISK 7136:2000 using a turbidity meter (NDH5000, manufactured by Nippon Denshoku Corporation).

[0071] (2) Acid value The acid values ​​of the resin and crosslinking agent were measured by the titration method described in JIS K-1557-5. 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.

[0072] (3) Coating surface quality (coating spots and coating defects) The film was hung in a dark room with a black felt background, and the coated surface of the film was observed using a 400-800 lumen LED flashlight to evaluate the quality of the coated surface. The quality of the coated surface was judged according to the following criteria. The evaluation area was 2m² of the coated surface. 2 It was deemed appropriate. application spot ⊚: The coated surface is uniform with no slight spots. ○: Small spots on the coated surface 5.0 / m 2 There are faint spots below or all over the surface. △: Small spots on the coated surface 6.0 to 10.0 / m 2 Or there are light spots all over the surface. ×: 11.0 small spots / m on the coated surface 2 There are spots on the upper or lower surface. The spots were classified according to the following criteria. The area of ​​the spot is 100 mm 2 If the number was less than 1, it was considered a small spot. The density of the spots was determined by cutting out the relevant areas from the film as determined by the above observation, and checking and classifying them in the following order. A piece of film was observed under an LED light source through transmission, and if mottle was visible, it was deemed mottle. If no mottle was visible through transmission, the film piece was then placed on black felt with the coated side facing up and visually inspected from above at a 45° angle from the film surface under an LED light source. If mottle was not observed in this way, it was judged to be faint mottle. If mottle was not observed in this way, it was again inspected from a different angle from above the film surface, and if mottle was visible, it was judged to be faint mottle. Coating defects ⊚: No defects in the coating layer. ○: 5.0 small defects / m2 in the coating layer 2 The following is the result. △: 2.0 defects / m 2 below. Or small defects 6.0 to 20.0 / m 2 is. ×: Defects in coating 3.0 / m 2or more or small defects 21.0 / m 2 That's all. The size of the defect was judged according to the following criteria. The relevant areas identified through the above observations were cut out from the film and observed under an optical microscope at 100x magnification. Defects measuring less than 1mm on the maximum side were considered to be small defects. Coating spots and coating defects were rated as "good" or better.

[0073] (4) 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. ◯: There is no transfer of the coating layer, but there is some resistance when peeling it 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. The standard was 0 or above to be considered a pass.

[0074] (5) 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-divided roll, and then the film with the ink layer was exposed to 100 or 40 mJ / cm using a high-pressure mercury lamp. 2The ink was then irradiated with ultraviolet light at 100 slits, curing the UV-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 firmly attached to the grid-shaped cuts. The cellophane adhesive tape was then peeled vertically from the ink layer surface of the ink laminated film, and the number of squares that peeled off 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 evaluated according to the following criteria. ◎: 100%, ○: 96-99%, △: 80-95%, ×: Less than 80% The standard was 0 or above to be considered a pass.

[0075] (6) Adhesion to the 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 firmly adhered. The cellophane adhesive tape was then peeled vertically from the hard coat layer surface of the hard coat laminate film. After performing the tape attachment and peeling operation five times at the same location, the number of squares peeled from the hard coat layer surface of the hard coat laminate film was visually counted, and the adhesion between the hard coat layer and the film substrate was calculated using the following formula. Note that 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 evaluated according to the following criteria. ◎: 100%, ○: 96-99%, △: 80-95%, ×: less than 80%. The standard was 0 or above to be considered a pass.

[0076] (7) Moisture and heat resistance The UV ink-coated film (BEST CURE UV161 White S) prepared in the same manner as above (5) and (6) was coated and then irradiated with UV at 100 mJ / cm. 2 The hard-coated film (cured product) or hard-coated film was 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 film was 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.

[0077] (Polymerization of polyurethane resin PU-A) A four-neck flask equipped with a stirrer, Dimroth condenser, nitrogen inlet tube, silica gel drying tube, and thermometer was charged with 23.6 parts by weight of hydrogenated xylylene diisocyanate, 12.0 parts by weight of dimethylolpropionic acid, 65.0 parts by weight of polycarbonate diol (1,6-hexanediol type) with a number average molecular weight of 1800, 3.0 parts by weight, and 123 parts by weight of ethyl methyl ketone as a solvent. The mixture was stirred at 75°C under a nitrogen atmosphere for 3 hours, and the reaction solution was confirmed to have reached the required amine equivalent. The reaction solution was cooled to below room temperature to obtain a polyurethane resin (PU-A) solution with a solids content of 45.0% by weight. The acid value of the solids content of this polyurethane resin (PU-A) solution was 50.0 mgKOH / g.

[0078] (Preparation of aqueous dispersion of polyurethane resin PU-A-1 (PU-A-1WD)) To the polyurethane resin (PU-A) solution, a predetermined amount of dimethylethanolamine (boiling point 134°C) and triethylamine (boiling point 89°C) was added at room temperature, and the mixture was stirred for 30 minutes to obtain polyurethane resin (PU-A-1) in which the carboxyl groups of the polyurethane resin (PU-A) were converted to the amine salt of dimethylethanolamine and triethylamine in a 50 / 50 ratio, as shown in Table 1. Next, a predetermined amount of water was added to a reaction vessel equipped with a homodisperser capable of high-speed stirring, and the mixture was stirred for 2000 min at 25°C. -1 While stirring and mixing at 50°C, the polyurethane resin (PU-A-1) solution was added and dispersed in water. The solvent, ethyl methyl ketone, was then removed under reduced pressure. The concentration was adjusted with water to prepare an aqueous dispersion (PU-A-1WD) of polyurethane resin (PU-A) with a solids content of 35% by mass.

[0079] (Preparation of aqueous dispersions of polyurethane resins PU-A-2 to PU-A-5) An aqueous dispersion was prepared in the same manner as in the preparation of the aqueous dispersion of polyurethane resin PU-A-1 (PU-A-1WD) described above, except that the type and ratio of the amines added were changed according to the corresponding polyurethane resin, as shown in Table 1.

[0080] (Preparation of aqueous dispersion of polyurethane resin PU-B-1 (PU-B-1WD)) A four-neck flask equipped with a stirrer, Dimroth condenser, nitrogen inlet tube, silica gel drying tube, and thermometer was charged with 28.0 parts by weight of hydrogenated diphenylmethane diisocyanate, 7.0 parts by weight of dimethylolpropionic acid, 64.0 parts by weight of polyester diol with a number average molecular weight of 2000 (composition: sebacic acid / / neopentyl glycol / / 1,6-hexanediol = 100 / / 60 / 40 (molar ratio)), 3.0 parts by weight of neopentyl glycol, and 125 parts by weight of ethyl methyl ketone as a solvent. The mixture was stirred under a nitrogen atmosphere at 75 °C for 3 hours, and the reaction solution was confirmed to have reached the required amine equivalent. The reaction solution was cooled to below room temperature to obtain a polyurethane resin (PU-B) solution with a solids content of 45.0% by weight. The acid value of the solids content of this polyurethane resin (PU-B) solution was 28.6 mg KOH / g. To this reaction mixture, predetermined amounts of triethanolamine (boiling point 335°C) and dimethylaminomethanol (boiling point 88°C) were added at room temperature, and the mixture was stirred for 30 minutes to obtain polyurethane resin (PU-B-1), in which the carboxyl groups of polyurethane resin (PU-B) were converted to the amine salt of triethanolamine and dimethylaminomethanol in a ratio of 30 / 70, as shown in Table 1. Next, a predetermined amount of water was added to a reaction vessel equipped with a homodisperser capable of high-speed stirring, and the mixture was stirred for 2000 min at 25°C. -1 While stirring and mixing at 50°C, the polyurethane resin (PU-B-1) solution was added and dispersed in water. The solvent, ethyl methyl ketone, was then removed under reduced pressure. The concentration was adjusted with water to prepare an aqueous dispersion (PU-B-1WD) of polyurethane resin (PU-B-1) with a solids content of 35% by mass.

[0081] (Preparation of aqueous dispersion of polyurethane resin PU-C-1 (PU-C-1WD)) A four-neck flask equipped with a stirrer, Dimroth condenser, nitrogen inlet tube, silica gel drying tube, and thermometer was charged with 27.0 parts by weight of hydrogenated diphenylmethane diisocyanate, 5.0 parts by weight of dimethylolpropionic acid, 64.0 parts by weight of polycarbonate diol (1,6-hexanediol type) having a number average molecular weight of 1000, 3.5 parts by weight of polyethylene glycol having a number average molecular weight of 1000, and 122 parts by weight of ethyl methyl ketone as a solvent. The mixture was stirred at 75 °C under a nitrogen atmosphere for 3 hours, and it was confirmed that the reaction solution reached the required amine equivalent. The reaction solution was cooled to below room temperature to obtain a polyurethane resin (PU-C) solution with a solids content of 45.0% by weight. The acid value of the solids content of this polyurethane resin (PU-C) solution was 21.0 mgKOH / g. A predetermined amount of triethylamine (boiling point 89°C) was added to this reaction solution at room temperature, and the mixture was stirred for 30 minutes to obtain polyurethane resin (PU-C-1) in which 100% of the carboxyl groups in the polyurethane resin (PU-C) were converted to the amine salt of triethylamine, as shown in Table 1. Next, a predetermined amount of water was added to a reaction vessel equipped with a homodisperser capable of high-speed stirring, and the mixture was stirred for 2000 min at 25°C. -1 While stirring and mixing at 50°C, the polyurethane resin (PU-C-1) solution was added and dispersed in water. The solvent, ethyl methyl ketone, was then removed under reduced pressure. The concentration was adjusted with water to prepare an aqueous dispersion (PU-C-1WD) of polyurethane resin (PU-C-1) with a solids content of 35% by mass.

[0082] (Preparation of aqueous dispersion of polyurethane resin PU-D-1 (PU-D-1WD)) A four-neck flask equipped with a stirrer, Dimroth condenser, nitrogen inlet, silica gel drying tube, and thermometer was charged with 23.2 parts by weight of hydrogenated xylylene diisocyanate, 2.2 parts by weight of dimethylolpropionic acid, 50.0 parts by weight of polycarbonate diol (1,6-hexanediol type) with a number average molecular weight of 1000, 20.0 parts by weight of polyethylene glycol with a number average molecular weight of 1000, 4.0 parts by weight of neopentyl glycol, and 122 parts by weight of ethyl methyl ketone as a solvent. The mixture was stirred at 75°C under a nitrogen atmosphere for 3 hours, and the reaction solution was confirmed to have reached the required amine equivalent. The reaction solution was cooled to below room temperature to obtain a polyurethane resin (PU-D) solution with a solids content of 45.0% by weight. The acid value of the solids content of this polyurethane resin (PU-D) solution was 9.3 mgKOH / g. To this reaction solution, predetermined amounts of dimethylethanolamine (boiling point 134°C) and triethylamine (boiling point 89°C) were added at room temperature, and the mixture was stirred for 30 minutes to obtain polyurethane resin (PU-D-1), in which the carboxyl groups of polyurethane resin (PU-D) were converted to the amine salt of dimethylethanolamine and triethylamine in a 50 / 50 ratio, as shown in Table 1. Next, a predetermined amount of water was added to a reaction vessel equipped with a homodisperser capable of high-speed stirring, and the mixture was stirred for 2000 min at 25°C. -1 While stirring and mixing at 50°C, the polyurethane resin (PU-D-1) solution was added and dispersed in water. The solvent, ethyl methyl ketone, was then removed under reduced pressure. The concentration was adjusted with water to prepare an aqueous dispersion (PU-D-1WD) of polyurethane resin (PU-D-1) with a solids content of 35% by mass.

[0083] (Preparation of aqueous dispersion of polyurethane resin PU-E-1 (PU-E-1WD)) A four-neck flask equipped with a stirrer, Dimroth condenser, nitrogen inlet, silica gel drying tube, and thermometer was charged with 28.5 parts by weight of hydrogenated xylylene diisocyanate, 14.0 parts by weight of dimethylolpropionic acid, 48.0 parts by weight of polycarbonate diol (1,6-hexanediol type) with a number average molecular weight of 1000, and 111 parts by weight of ethyl methyl ketone as a solvent. The mixture was stirred at 75°C under a nitrogen atmosphere for 3 hours, and the reaction solution was confirmed to have reached the required amine equivalent. The reaction solution was cooled to below room temperature to obtain a polyurethane resin (PU-E) solution with a solids content of 45.0% by weight. The acid value of the solids content of this polyurethane resin (PU-E) solution was 54.7 mgKOH / g. To this reaction solution, predetermined amounts of triethanolamine (boiling point 335°C) and triethylamine (boiling point 89°C) were added at room temperature, and the mixture was stirred for 30 minutes to obtain polyurethane resin (PU-E-1) in which the carboxyl groups of the polyurethane resin (PU-E) were converted to the amine salt of triethanolamine and triethylamine in a ratio of 70 / 30, as shown in Table 1. Next, a predetermined amount of water was added to a reaction vessel equipped with a homodisperser capable of high-speed stirring, and the mixture was stirred for 2000 min at 25°C. -1 While stirring and mixing at 50°C, the polyurethane resin (PU-E-1) solution was added and dispersed in water. The solvent, ethyl methyl ketone, was then removed under reduced pressure. The concentration was adjusted with water to prepare an aqueous dispersion (PU-E-1WD) of polyurethane resin (PU-E-1) with a solids content of 35% by mass.

[0084] (Polymerization of copolymer polyester resin PES-A) A stainless steel autoclave equipped with a stirrer, thermometer, and partial reflux condenser was charged with 150.0 parts by weight of dimethyl 2,6-naphthalenedicarboxylate, 226.0 parts by weight of dimethyl terephthalate, 35.0 parts by weight of 1,6-hexanediol, 1.2 parts by weight of trimethylolpropane, 131.0 parts by weight of ethylene glycol, and 0.2 parts by weight of tetra-n-butyl titanate, and a transesterification reaction was carried out at a temperature of 160 to 220°C for 4 hours. Next, 45.0 parts by weight of sebacic acid was added, and the reaction was carried out at 220°C for 1 hour. The temperature of the system was then raised to 250°C, and the system was gradually reduced in pressure to 30 Pa, after which the reaction was carried out for 1 hour and 30 minutes. Furthermore, nitrogen was introduced into the system to release the reduced pressure, and the system was cooled to 200°C. 51.0 parts by mass of trimellitic anhydride was added to the system while stirring, and the addition reaction was continued for another 2 hours to obtain a copolymer polyester resin (PES-A). The obtained copolymer polyester resin (PES-A) was pale yellow and transparent. The reduced viscosity of the copolymer polyester resin (PES-A) was measured to be 0.65 dL / g, and the acid value was 46.6 mg KOH / g.

[0085] (Preparation of aqueous dispersion of copolymer polyester resin PES-A-1 (PES-A-1WD)) The copolymer polyester resin (PES-A) and the solvent tetrahydrofuran were added to a reactor equipped with a stirrer, thermometer, and reflux device in a predetermined amount so that the solid content was 60% by mass, and the mixture was heated to 50°C and stirred to dissolve the resin. After the resin was completely dissolved, the predetermined amounts of N,N-dipropylethylamine (boiling point 132°C) and N-butyldimethylamine (boiling point 93°C) were added as shown in Table 1 to prepare copolymer polyester resin (PES-A-1). Next, this system was stirred for 400 min. -1 While stirring and mixing at 50°C, a predetermined amount of water was gradually added. The solvent, tetrahydrofuran, was then removed under reduced pressure. The concentration was adjusted with water to prepare an aqueous dispersion (PES-A-1WD) of the copolymer polyester resin (PES-A-1) with a solids content of 35% by mass.

[0086] (Preparation of Water Dispersion of Copolymer Polyester Resin PES-A-2 (PES-A-2WD)) The copolymer polyester resin (PES-A) and the solvent tetrahydrofuran were added to a reactor equipped with a stirrer, thermometer, and reflux device in a predetermined amount so that the solid content was 60% by mass, and the mixture was heated to 50°C and stirred to dissolve the resin. After the resin was completely dissolved, a predetermined amount of dimethylethanolamine (boiling point 134°C) was added as shown in Table 1 to prepare copolymer polyester resin (PES-A-2). Next, this system was stirred for 400 min. -1 While stirring and mixing at 50°C, a predetermined amount of water was gradually added. The solvent, tetrahydrofuran, was then removed under reduced pressure. The concentration was adjusted with water to prepare an aqueous dispersion (PES-A-2WD) of the copolymer polyester resin (PES-A-2) with a solids content of 35% by mass.

[0087] (Polymerization of copolymer polyester resin PES-B) A stainless steel autoclave equipped with a stirrer, thermometer, and partial reflux condenser was charged with 194.2 parts by weight of dimethyl terephthalate, 184.5 parts by weight of dimethyl isophthalate, 14.8 parts by weight of dimethyl-5-sodium sulfoisophthalate, 128.0 parts by weight of diethylene glycol, 75.0 parts by weight of ethylene glycol, and 0.2 parts by weight of tetra-n-butyl titanate. The transesterification reaction was carried out at a temperature of 160 to 220°C for 4 hours. The temperature was then raised to 255°C, and the reaction system was gradually reduced in pressure. The reaction was then carried out under a reduced pressure of 30 Pa for 1 hour and 30 minutes to obtain a copolymer polyester resin (PES-B). The resulting copolymer polyester resin (PES-B) was a pale yellow, transparent solid with a reduced viscosity of 0.70 dL / g. The acid value was 0.1 mgKOH / g.

[0088] (Preparation of aqueous dispersion of copolymer polyester resin PES-B (PES-BWD)) Equal parts by mass of copolymer polyester resin (PES-B) and ethylene glycol-n-butyl ether were placed in a reactor equipped with a stirrer, thermometer, and reflux device, and the mixture was heated to 110°C and stirred to dissolve the resin. After the resin was completely dissolved, a predetermined amount of water was gradually added to the polyester solution while stirring, and after the addition was completed, the liquid was cooled to room temperature while stirring. An appropriate amount of water was added to prepare an aqueous dispersion of copolymer polyester resin PES-B (PES-BWD) with a solids content of 30% by mass.

[0089] (Polymerization of copolymer polyester resin PES-C) A stainless steel autoclave equipped with a stirrer, thermometer, and partial reflux condenser was charged with 240.0 parts by weight of dimethyl 2,6-naphthalenedicarboxylate, 120.0 parts by weight of dimethyl terephthalate, 36.0 parts by weight of dimethyl-5-sodium sulfoisophthalate, 49.0 parts by weight of diethylene glycol, 95.0 parts by weight of 1,6-hexanediol, 200.0 parts by weight of ethylene glycol, and 0.2 parts by weight of tetra-n-butyl titanate, and the mixture was subjected to a transesterification reaction at a temperature of 160 to 220°C for 4 hours. Next, 45.0 parts by weight of adipic acid was added, and the mixture was reacted at 220°C for 1 hour. The temperature of the system was then raised to 250°C, and the pressure was gradually reduced to 30 Pa. The temperature was then raised to 255°C, and the mixture was reacted under reduced pressure for 1 hour and 30 minutes to obtain a copolymer polyester resin (PES-C). The resulting copolymer polyester resin (PES-C) was a pale yellow, transparent solid, and had a reduced viscosity of 0.60 dL / g and an acid value of 0.2 mg KOH / g.

[0090] (Preparation of aqueous dispersion of PES-C copolymer polyester resin (PES-CWD)) Equal parts by mass of copolymer polyester resin (PES-C) and ethylene glycol t-butyl ether were placed in a reactor equipped with a stirrer, thermometer, and reflux device, and heated to 100°C with stirring to dissolve the resin. After the resin was completely dissolved, a specified amount of water was gradually added to the polyester solution while stirring, and after the addition was completed, the liquid was cooled to room temperature while stirring. An appropriate amount of water was added to prepare an aqueous dispersion of copolymer polyester resin PES-C (PES-CWD) with a solids content of 30% by mass.

[0091] (Acrylic resin (AC-A polymerization) A flask equipped with a stirrer, thermometer, and reflux condenser was charged with 47.0 parts by weight of propylene glycol monomethyl ether. The flask was heated to 100°C and maintained at this temperature. A mixture of 30.0 parts by weight of normal butyl acrylate, 60.0 parts by weight of ethyl acrylate, 12.0 parts by weight of 2-hydroxyethyl methacrylate, 7.8 parts by weight of acrylic acid, and 5 parts by weight of azobisisobutyronitrile was added dropwise over 3 hours. After the dropwise addition, the mixture was aged at the same temperature for 2 hours. The reaction solution was cooled to below room temperature to obtain an acrylic resin (AC-A) solution with a solids content of 70.0% by weight. The acid value of the solids content of this acrylic resin (AC-A) solution was 55.3 mgKOH / g.

[0092] (Preparation of water dispersion (AC-A-1WD) of acrylic resin (AC-A-1)) To the acrylic resin (AC-A) solution, a predetermined amount of tributylamine (boiling point 217°C) and triethylamine (boiling point 89°C) was added at room temperature, and the mixture was stirred for 30 minutes to obtain acrylic resin (AC-A-1) in which the carboxyl groups of the acrylic resin (AC-A) were converted into amine salts of tributylamine and triethylamine in a ratio of 40 / 60, as shown in Table 1. Next, a predetermined amount of water was added to a reaction vessel equipped with a homodisperser capable of high-speed stirring, and the mixture was stirred for 2000 min at 25°C. -1 The acrylic resin (AC-A-1) solution was added and dispersed in water while stirring and mixing at 50°C. The concentration was adjusted with water to prepare an aqueous dispersion (AC-A-1WD) of the acrylic resin (AC-A-1) with a solid content of 30% by mass.

[0093] (Preparation of water dispersion (AC-A-2WD) of acrylic resin (AC-A-2)) A predetermined amount of triethylamine (boiling point 89°C) was added to the acrylic resin (AC-A) solution at room temperature and stirred for 30 minutes to obtain acrylic resin (AC-A-2) in which the carboxyl groups of the acrylic resin (AC-A) were converted to the amine salt of triethylamine in a ratio of 100, as shown in Table 1. Next, a predetermined amount of water was added to a reaction vessel equipped with a homodisperser capable of high-speed stirring, and the temperature was adjusted to 25°C. The mixture was stirred for 2000 min. -1 The acrylic resin (AC-A-2) solution was added and dispersed in water while stirring and mixing at 50°C. The concentration was adjusted with water to prepare an aqueous dispersion (AC-A-2WD) of the acrylic resin (AC-A-2) with a solid content of 30% by mass.

[0094] (Polymerization of acrylic resin (AC-B)) A flask equipped with a stirrer, thermometer, and reflux condenser was charged with 42.9 parts by weight of propylene glycol monomethyl ether. The flask was heated to 100°C and maintained at this temperature. A mixture of 28.0 parts by weight of ethyl acrylate, 16.0 parts by weight of octyl acrylate, 20.0 parts by weight of 2-hydroxyethyl methacrylate, 31.0 parts by weight of methyl methacrylate, 5.0 parts by weight of methacrylic acid, and 5 parts by weight of azobisisobutyronitrile was added dropwise over 3 hours. After the dropwise addition, the mixture was aged at the same temperature for 2 hours. The reaction solution was cooled to below room temperature to obtain an acrylic resin (AC-B) solution with a solids content of 70.0% by weight. The acid value of the solids content of this acrylic resin (AC-B) solution was 32.6 mgKOH / g.

[0095] (Adjustment of acrylic resin (AC-B-1)) A predetermined amount of triethylamine (boiling point 89°C) was added to the aforementioned acrylic resin (AC-B) solution at room temperature, and the mixture was stirred for 30 minutes to obtain an acrylic resin (AC-B-1) solution in which 50% of the carboxyl groups in the acrylic resin (AC-B) were converted to the amine salt of triethylamine, as shown in Table 1.

[0096] (Preparation of water dispersion (AC-B-1WD) of acrylic resin (AC-B-1)) A predetermined amount of water was added to a reaction vessel equipped with a homodisperser capable of high-speed stirring, and the mixture was stirred at 25°C for 2000 min. -1 While stirring and mixing at 50°C, the acrylic resin (AC-B-1) solution was added and dispersed in water. The concentration was adjusted with water to prepare an aqueous dispersion (AC-B-1WD) of the acrylic resin (AC-B-1) with a solid content of 30% by mass.

[0097] The acid values ​​of the polyurethane resin, polyester resin, and acrylic resin mentioned above, as well as the types and ratios of the amine compounds used, are shown in Table 1.

[0098] (Preparation of blocked isocyanate crosslinking agent (C-1) solution) A flask equipped with a stirrer, thermometer, and reflux condenser was charged with 58.0 parts by weight of a polyisocyanate compound having an isocyanurate structure (Duranate TPA-100, manufactured by Asahi Kasei Chemicals) derived from hexamethylene diisocyanate, 25.0 parts by weight of N-methylpyrrolidone, 25.0 parts by weight of 3,5-dimethylpyrazole, and 15.0 parts by weight of polyethylene glycol monomethyl ether having a number average molecular weight of 500. The mixture was then maintained at 70°C for 2 hours under a nitrogen atmosphere. Then, 2.0 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, an appropriate amount of water was added while stirring to prepare a blocked isocyanate crosslinking agent (C-1) solution with a solids content of 40.0% by weight.

[0099] (Preparation of blocked isocyanate crosslinking agent (C-2) solution) In a flask equipped with a stirrer, thermometer, and reflux condenser, 63.0 parts by mass of a polyisocyanate compound having an isocyanurate structure (Duranate TPA-100, manufactured by Asahi Kasei Chemicals) derived from hexamethylene diisocyanate, 25.0 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 under a nitrogen atmosphere for 1 hour. Then, 9.0 parts by mass of dimethylolpropionic acid were 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 dimethylethanolamine was added. After stirring for 1 hour, an appropriate amount of water was added to prepare a blocked isocyanate crosslinking agent (C-2) solution with a solids content of 40% by mass.

[0100] (Preparation of oxazoline crosslinker (C-3) solution) A flask equipped with a stirrer, thermometer, and reflux condenser was charged with 50.0 parts by weight of water and 50.0 parts by weight of methoxypropyl alcohol and heated to 80°C under a nitrogen atmosphere. Subsequently, a monomer mixture consisting of 21.9 parts by weight of methyl methacrylate, 24.3 parts by weight of 2-isopropenyl-2-oxazoline, and 38.3 parts by weight of an ester compound of polyethylene glycol and methacrylic acid (n = 10), and a polymerization initiator solution consisting of 5.0 parts by weight of 2,2'-azobis(2-amidinopropane) dihydrochloride and 50.0 parts by weight of water were added dropwise from a dropping funnel over 2 hours under a nitrogen atmosphere while maintaining the flask at 80°C. After the 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-3) solution with a solids content of 40% by weight.

[0101] (Synthesis of carbodiimide crosslinker (C-4)) In a flask equipped with a stirrer, thermometer, and reflux condenser, 63.2 parts by weight of hydrogenated diphenylmethane diisocyanate and 0.3 parts by weight of 3-methyl-1-phenyl-2-phospholene-1-oxide as a carbodiimidization catalyst were reacted at 180°C for 18 hours, and it was confirmed that the reaction solution reached the specified amine equivalent. Next, 36.4 parts by weight of polyethylene glycol monomethyl ether having a number average molecular weight of 400 was added, and the reaction was carried out at 150°C for 5 hours. After the reaction, the mixture was cooled to 50°C, and a specified amount of water was gradually added to prepare a carbodiimide-based crosslinking agent (C-4) solution with a solids content of 40% by weight.

[0102] (particle) (Particle P-1) As the particles (P-1), colloidal silica (Snowtex O; manufactured by Nissan Chemical Industries, Ltd.) having a solid content of 20% by mass and an average particle size of 10 to 15 nm was used as it was as a particle (P-1) solution.

[0103] (Particle P-2) As the particles (P-2), colloidal silica (Seahoster KE-W50; Nippon Shokubai) with a solid content of 20% by mass and an average particle size of 500 nm was used as it was as a particle (P-2) solution.

[0104] (Particle P-3) As the particles (P-3), zirconia particles (ZSL00014; Daiichi Kigenso Kagaku Kogyo) with a solid content of 20 mass % and an average particle size of 10 to 20 nm were used as is as a particle (P-3) solution.

[0105] (Preparation of acrylic resin-treated particles (P-3-A)) In a flask equipped with a stirrer and a thermometer, 50 parts by mass of the particle (P-3) solution was gradually added with 5 parts by mass of the acrylic resin (AC-B-1) solution while stirring. After the addition was completed, the mixture was stirred at room temperature for 1 hour, and then a predetermined amount of water was added to prepare acrylic resin-treated particles (P-3-A) with a solids concentration of 20% by mass.

[0106] (additives) (Preparation of Additive (A-1) Solution) Triethanolamine (boiling point 335°C) and a predetermined amount of water were added to a flask equipped with a stirrer and a thermometer and dissolved to prepare an additive (A-1) solution with a solid content concentration of 20 mass %.

[0107] (Preparation of Additive (A-2) Solution) A flask equipped with a stirrer and a thermometer was charged with 28% by mass of aqueous ammonia (amine boiling point -33°C) and a predetermined amount of water to dilute the solution, thereby preparing a 20% by mass solution of additive (A-2).

[0108] (Production of polyester resin (E-1) for substrate) (Preparation of antimony trioxide solution) Antimony trioxide (Sigma-Aldrich Japan LLC) was placed in a flask together with ethylene glycol, dissolved by stirring at 150°C for 4 hours, and then cooled to room temperature to prepare a 20 g / L ethylene glycol solution of antimony trioxide.

[0109] (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 based on 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 this BHET mixture as a polycondensation catalyst so that the amount was 0.04 mol % in terms of antimony atoms based on the acid component in the polyester, and the mixture was then stirred for 10 minutes at 250°C under a nitrogen atmosphere and atmospheric pressure. Thereafter, the temperature was 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 at 280°C and 13.3 Pa for a further 68 minutes, yielding a polyester resin (E-1) having an intrinsic viscosity (IV) of 0.61 dL / g (solvent: phenol / tetrachloroethane = 60 / 40) and containing substantially no particles.

[0110] (Production of polyester resin (E-2) for substrate) (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, and the mixture was stirred at room temperature for 6 hours. After that, the mixture was stirred under reduced pressure (133 Pa) at 70 to 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.

[0111] (Example of preparation of phosphorus compound solution) Diethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate (Irganox 1222 (BASF)) as a phosphorus compound 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.

[0112] (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.

[0113] (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 / g and containing substantially no particles.

[0114] Example 1 (1) Preparation of coating solution (No. 1) The following coating materials were mixed with a water and isopropanol mixed solvent (80 / 20 parts by mass) to prepare a total of 100 parts by mass. The solids mass ratio of the polyurethane resin PU-A-1 aqueous dispersion (PU-A-1WD) / blocked isocyanate crosslinker (C-1) solution was 80 / 20, with a total solid resin concentration of 4% by mass. Next, the solids mass ratios of particles (PA-1) and particles (PA-2) were 12.0 and 0.4, respectively, based on a total solids content of 100% of the aforementioned resins. Furthermore, 1% by mass of a 10% aqueous solution of a silicone surfactant was added to this coating solution to prepare coating solution (No. 1). The blending ratios of resins and other components in each coating solution are shown in Table 2.

[0115] Example of preparation of coating liquid No. 1 Mixed solvent (water / isopropanol) 85.38 parts by mass Water dispersion of polyurethane resin PU-A-1 (PU-A-1WD) 9.14 parts by mass Blocked isocyanate crosslinking agent (C-1) solution 2.00 parts by mass Particle (PA-1) solution 2.40 parts by mass Particle (PA-2) solution 0.08 parts by mass Surfactant aqueous solution 1.00 parts by mass Total 100.00 parts by mass

[0116] (2) Manufacturing of laminated polyester film Resin pellets of polyester resin (E-1) used as the raw resin 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, melt-extruded into a sheet at approximately 280°C, and rapidly cooled and solidified on a rotating cooling metal roll maintained at a surface temperature of 20°C to obtain an unstretched PET sheet.

[0117] 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.

[0118] Next, the coating solution (No. 1) was applied to one side of the PET film in a final (biaxially stretched) dried coating amount of 0.08 g / m 2 After coating, the film was dried by heat treatment at 90°C for 3 seconds and at 40°C for 3 seconds. The film was then stretched 4.0 times in the width direction at 110°C, and, with the film fixed in the width direction, heated at 230°C for 5 seconds. A further 3% relaxation treatment in the width direction was carried out to obtain a 100 μm thick laminated polyester film. The thickness of the coating layer was 70 nm. The evaluation results of this film are shown in Table 3.

[0119] Examples 2 to 12 A laminated polyester film was obtained in the same manner as in Example 1, except that the coating solution of Example 1 was replaced with the coating solution No. shown in Table 3. The types and blending ratios of resins and the like used in each coating solution No. were those shown in Table 2. In Examples 10 to 12, additive (A-1) was added to the coating solution.

[0120] Example 13 A laminated polyester film was obtained in the same manner as in Example 1, except that E-2 was used instead of E-1 as the raw material resin for the film.

[0121] (Comparative Examples 1 to 10) A laminated polyester film was obtained in the same manner as in Example 1, except that the coating solution of Example 1 was replaced with the coating solution No. listed in each comparative example in Table 3. In Comparative Example 10, additive (A-2) was added to the coating solution.

[0122] Table 3 shows the evaluation results for each of the examples and comparative examples.

[0123] As shown in Table 3, satisfactory results were obtained in haze, blocking resistance, adhesion to UV ink, adhesion to the hard coat layer, and moist heat resistance in each of Examples 1 to 13. On the other hand, the results were not satisfactory in Comparative Examples 1 to 10.

[0124] [Table 1]

[0125] [Table 2]

[0126] [Table 3] [Industrial Applicability]

[0127] The present invention makes it possible to provide a laminated polyester film having optimum adhesive properties for use in a wide range of fields, including optical applications, packaging applications, and label applications.

Claims

1. A method for manufacturing a laminated film comprising a coating layer on at least one surface of a polyester film substrate, The formation of the coating layer includes the following steps: A composition comprising a resin having at least one carboxyl group selected from polyester resin, polyurethane resin, and acrylic resin, and two amine compounds having a boiling point of 60°C or higher and a boiling point difference of 40°C or higher, is applied to at least one surface of the polyester film substrate; Of the two amine compounds having a boiling point of 60°C or higher and a boiling point difference of 40°C or higher, One type of amine compound is amine compound (A) having a boiling point of 107°C or higher. The other amine compound is amine compound (B), which has a lower boiling point than amine compound (A). A method for manufacturing laminated films.

2. The composition that forms the coating layer is The aqueous dispersion comprises a resin having at least one carboxyl group selected from the polyester resin, the polyurethane resin, and the acrylic resin, In the preparation step of the aqueous dispersion, The amine compound (A) and the amine compound (B) are added. A method for producing a laminated polyester film according to claim 1.