Antistatic polyester film

Abstract

Provided is an antistatic polyester film that has good adhesion to an antistatic layer and is excellent in maintaining a high level of adhesion over a long period of time. An antistatic polyester film in which an easily adherable layer is formed by curing a coating layer formed of a composition containing a polyurethane resin having a carboxyl group and an acid value of 30 to 50 mgKOH / g and a crosslinking agent having a carboxyl group and an acid value of 30 to 50 mgKOH / g is sequentially layered on at least one side of a polyester film.

Description

Technical Field

[0001] This invention relates to antistatic polyester films. More specifically, it relates to antistatic polyester films having an antistatic layer and an adhesive layer laminated on the antistatic layer, and particularly to protective films for optical components (e.g., organic EL, components of liquid crystal displays).

[0002] Thermoplastic resin films, especially polyester films, possess excellent mechanical, electrical, dimensional stability, transparency, and chemical resistance properties. Therefore, they are widely used in magnetic recording materials, packaging materials, solar cells, anti-reflective films, diffusers, prism sheets, and other optical films in flat panel displays, as well as label printing films, antistatic films, and protective films. However, the highly crystalline orientation of polyester film surfaces results in a disadvantage: poor adhesion to various coatings, resins, and inks during processing for these applications.

[0003] Therefore, research has been conducted on various methods to impart adhesive properties to the surface of polyester films.

[0004] Conventionally, methods for imparting adhesiveness include surface activation methods such as corona discharge treatment, ultraviolet irradiation treatment, and plasma treatment on the surface of a polyester film as a substrate. However, the adhesiveness obtained by these treatments will decrease over time, making it difficult to maintain a high level of adhesiveness for a long period of time (Patent Document 1).

[0005] Therefore, the method of coating various resins on the surface of polyester film and setting a coating layer with easy adhesion properties is widely used.

[0006] Previously, techniques were known to involve using coating liquids containing copolyester resins or urethane resins, or coating liquids combining these resins and crosslinking agents, to apply to coating layers in order to improve affinity with resin components such as polyurethane acrylates or ester acrylates used as hard coating agents or prismatic agents, and to impart adhesion to them (Patent Documents 2, 3). However, in UV inks (ultraviolet-curing inks) used for label printing, in addition to resins, dyes or pigments are also contained to express hues, and pigments with good lightfastness are used at approximately 15-25% by weight of the ink component. Furthermore, in white ink systems where opacity is important, the content of white pigment can be as high as approximately 50% by weight. Therefore, existing techniques are insufficient in terms of adhesion, and adhesion at low doses is particularly difficult.

[0007] Regarding protective films, a technique of setting an antistatic layer and an adhesive layer on a polyester film has been proposed (Patent Document 4). However, in existing methods, the adhesion between the polyester film and the antistatic layer or adhesive layer is insufficient, and the durability after storage under high temperature and high humidity is particularly insufficient, resulting in a decrease in adhesion.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 58-27724

[0011] Patent Document 2: Japanese Patent Application Publication No. 2000-229355

[0012] Patent Document 3: Japanese Patent Application Publication No. 2009-220376

[0013] Patent Document 4: Japanese Patent Application Publication No. 2018-172473 Summary of the Invention

[0014] The problem the invention aims to solve

[0015] This invention was made in light of the problems described in the prior art. Specifically, the object of this invention is to provide an antistatic polyester film that exhibits good adhesion between the polyester film and the antistatic layer, and excellent long-term maintenance of a high level of adhesion.

[0016] Solution for solving the problem

[0017] That is, the present invention comprises the following components.

[0018] [1] An antistatic polyester film, wherein at least one side of the polyester film is sequentially laminated with an easy-to-adhere layer and an antistatic layer, wherein the easy-to-adhere layer is a layer formed by curing a composition comprising a polyurethane resin having a carboxyl group and an acid value of 30 to 50 mg KOH / g and a crosslinking agent having a carboxyl group and an acid value of 30 to 50 mg KOH / g.

[0019] [2] In one embodiment, the crosslinking agent is an isocyanate compound.

[0020] [3] In one method, the surface resistivity is 10 10 Below Ω / □.

[0021] [4] In one embodiment, the antistatic layer contains a conductive polymer.

[0022] [5] In one method, the membrane haze is below 3.0%.

[0023] [6] An adhesive film having an adhesive layer laminated on at least one side of the above-mentioned antistatic polyester film.

[0024] The effects of the invention

[0025] The antistatic polyester film of the present invention exhibits excellent adhesion to UV-curable resins such as hard coatings, lens layers, and inks, and is particularly excellent in terms of high-level adhesion to UV inks.

[0026] The antistatic polyester film of the present invention can provide an antistatic polyester film with excellent anti-adhesion properties, excellent initial adhesion between the antistatic layer and the easy-to-adhere layer and the polyester film substrate, and excellent resistance to damp heat adhesion. Detailed Implementation

[0027] (Polyester film substrate)

[0028] In this invention, the polyester resin constituting the polyester film substrate may include, in addition to polyethylene terephthalate, polybutylene terephthalate, polyethylene 2,6-naphthalenedicarboxylate, and polypropylene terephthalate, a copolymer polyester resin in which a portion of the diol component or dicarboxylic acid component of the above-mentioned polyester resin is replaced with the following copolymer components. For example, as copolymer components, diol components such as diethylene glycol, neopentyl glycol, 1,4-cyclohexanediol, and polyalkylene glycol may be included; dicarboxylic acid components such as adipic acid, sebacic acid, phthalic acid, isophthalic acid, sodium 5-isophthalate, and 2,6-naphthalenedicarboxylic acid may be included.

[0029] In this invention, the preferred polyester resin used for the polyester film substrate is mainly selected from polyethylene terephthalate, polyethylene terephthalate, polyethylene butylene terephthalate, and polyethylene 2,6-naphthalate. Among these polyester resins, polyethylene terephthalate is the most preferred in terms of balance between physical properties and cost. Furthermore, the polyester film substrate composed of these polyester resins is preferably a biaxially stretched polyester film, which can improve chemical resistance, heat resistance, mechanical strength, etc.

[0030] There are no particular limitations on the polycondensation catalyst used in the manufacture of polyester resins; antimony trioxide is suitable because it is inexpensive and has excellent catalytic activity. Germanium compounds or titanium compounds are also preferred. More preferred polycondensation catalysts include catalysts containing aluminum and / or its compounds and phenolic compounds, catalysts containing aluminum and / or its compounds and phosphorus compounds, and catalysts containing aluminum salts of phosphorus compounds.

[0031] Furthermore, there are no particular limitations on the layer composition of the polyester film substrate of the present invention. It can be a single-layer polyester film, a two-layer structure with different components, or a polyester film substrate having an outer layer and an inner layer, comprising at least three layers.

[0032] (Easy-to-bond layer)

[0033] To improve adhesion to the antistatic layer and adhesive layer, and to enhance resistance to adhesion, the antistatic polyester film of the present invention preferably has an easy-adhesive layer laminated on at least one side of the polyester film substrate. This easy-adhesive layer is formed from a polyurethane resin having carboxyl groups and an acid value of 30–50 mg KOH / g, and a crosslinking agent having carboxyl groups and an acid value of 30–50 mg KOH / g. The easy-adhesive layer can be disposed on both sides of the polyester film, or it can be disposed on only one side of the polyester film, with a dissimilar resin coating layer on the other side.

[0034] The easy-to-adhesive layer of this invention exhibits excellent adhesion to UV-curable or thermosetting resins such as antistatic layers, hard coatings, lens layers, and inks. Furthermore, by ensuring that both the polyurethane resin and the crosslinking agent possess a specified range of carboxyl groups, it is possible to suppress defects such as reduced water resistance due to a higher carboxyl group content in the monomer resin, thereby mitigating issues related to damp heat resistance. Additionally, the easy-to-adhesive layer itself contains a higher concentration of carboxyl groups.

[0035] The polyurethane resin having carboxyl groups and the crosslinking agent having carboxyl groups are preferably in the range of 90 / 10 to 10 / 90 by weight, more preferably in the range of 80 / 20 to 20 / 80, and even more preferably in the range of 70 / 30 to 30 / 70. When the amount of crosslinking agent is small, the durability, such as resistance to damp heat, decreases, and when the amount of polyurethane resin is small, the adhesion decreases.

[0036] The following provides a detailed description of the components of the easy-to-adhere layer.

[0037] (Polyurethane resin with carboxyl groups and an acid value of 30-50 mg KOH / g)

[0038] Carboxyl-containing polyurethane resins are urethane resins synthesized from at least a polyol component and a polyisocyanate component, and chain extenders as needed, and which have carboxyl groups in the molecule or on the side chain. Here, "in the molecule" refers to the presence of carboxyl groups in or at the ends of the main chain of the aforementioned polyurethane resin. Furthermore, "side chain" refers to a structure in which three or more terminal functional groups of any of the aforementioned raw material components constituting the molecular chain are present, thereby being introduced into the branched molecular chain after synthesis and polymerization.

[0039] The polyurethane resin with carboxyl groups in this invention is obtained by primarily using a polyol component containing carboxyl groups as the component of the urethane ester.

[0040] The following substances can be listed as examples of polyol components containing carboxyl groups.

[0041] Higher molecular weight compounds can be used, such as carboxyl-containing polyalkylene glycols, carboxyl-containing acrylic polyols, carboxyl-containing polyolefin polyols, and carboxyl-containing polyester polyols. Alternatively, lower molecular weight compounds can be used, such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolbutyric acid, and 2,2-dimethylolvalerate. For carboxyl group introduction, dimethylolpropionic acid and dimethylolbutyric acid are particularly preferred.

[0042] The acid value of the polyurethane resin containing carboxyl groups is preferably 30–50 mg KOH / g, more preferably 35–45 mg KOH / g. An acid value of 30 mg KOH / g or higher improves adhesion to the antistatic layer and adhesive layer. On the other hand, an acid value of 50 mg KOH / g or lower maintains the water resistance of the coating layer, and the films are less prone to adhesion due to moisture absorption, which is therefore preferred. However, in the polyurethane resin of the present invention, to compensate for the water solubility or water dispersibility of the polyurethane resin, other hydrophilic groups, such as hydroxyl groups, ethers, sulfonic acids, phosphonic acids, quaternary ammonium compounds, etc., can be introduced within a range that does not degrade the performance.

[0043] The carboxyl groups in polyurethane resins can be neutralized with alkaline compounds. Examples of alkaline compounds 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 readily dissociate from the carboxyl groups upon heating are preferred. Examples of organic amine compounds include, for instance, primary, secondary, or tertiary amines with 1 to 20 carbon atoms, such as ammonia, methylamine, ethylamine, propylamine, isopropylamine, butylamine, 2-ethylhexylamine, cyclohexylamine, dimethylamine, diethylamine, dipropylamine, diisopropylamine, dibutylamine, trimethylamine, triethylamine, triisopropylamine, tributylamine, and ethylenediamine; cyclic amines such as morpholine, N-alkylmorpholine, and pyridine; and amines containing hydroxyl groups such as monoisopropanolamine, methylethanolamine, methylisopropanolamine, dimethylethanolamine, diisopropanolamine, diethanolamine, triethanolamine, diethylethanolamine, and triethanolamine.

[0044] As other polyol components used in the synthesis and polymerization of the urethane resin of the present invention, polycarbonate polyols are preferred, and aliphatic polycarbonate polyols containing excellent heat resistance and hydrolysis resistance are particularly preferred. Examples of aliphatic polycarbonate polyols include aliphatic polycarbonate diols and aliphatic polycarbonate triols, with aliphatic polycarbonate diols being preferred. Examples of aliphatic polycarbonate diols used in the synthesis and polymerization of the urethane resin having a polycarbonate structure of the present invention include, for example, aliphatic polycarbonate diols obtained by reacting one or more of the following diols—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, neopentanediol, diethylene glycol, and dipropylene glycol—with carbonates such as dimethyl carbonate, ethylene glycol carbonate, and phosgene.

[0045] The number average molecular weight of the polycarbonate polyol used in this invention is preferably 300 to 5000. More preferably, it is 400 to 4000, and most preferably, it is 500 to 3000. A number average molecular weight of 300 or higher improves the adhesion to the antistatic layer and adhesive layer, which is preferred. A number average molecular weight of 3000 or lower improves the resistance to adhesion, which is preferred.

[0046] Examples of polyisocyanates used for synthesizing and polymerizing the urethane resins of this invention include, for example, aliphatic diisocyanates with aromatic rings such as phthalimide diisocyanate; alicyclic diisocyanates such as isophorone diisocyanate, 4,4-dicyclohexylmethane diisocyanate, and 1,3-bis(isocyanate methyl)cyclohexane; aliphatic diisocyanates such as hexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate; or modified polyisocyanates containing isocyanurate bonds, biuret bonds, or ureocarbamate bonds made from diisocyanates, or polyisocyanates prepared by pre-addition of one or more diisocyanates with trimethylolpropane, etc. When using the above-mentioned aliphatic diisocyanates, alicyclic diisocyanates, or aliphatic diisocyanates with aromatic rings, there is no problem with yellowing, which is preferred.

[0047] Examples of chain extenders include diols such as ethylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, and 1,6-hexanediol; polyols such as glycerol, trimethylolpropane, and pentaerythritol; diamines such as ethylenediamine, hexamethylenediamine, and piperazine; amino alcohols such as monoethanolamine and diethanolamine; thiodiglycol such as thiodiethylene glycol; or water. Additionally, small amounts of polyols and polyamines with three or more functional groups can also be used.

[0048] To improve strength and hardness, the polyurethane resin of the present invention may have reactive groups such as end-capped isocyanates on the end or side chains.

[0049] (Cross-linking agent)

[0050] In this invention, a crosslinking agent having a carboxyl group and an acid value of 30–50 mg KOH / g is used. Furthermore, the carboxyl group of the crosslinking agent is neutralized with the aforementioned polyurethane resin using an alkaline compound. The acid value of the crosslinking agent having a carboxyl group is preferably 30–50 mg KOH / g, more preferably 35–45 mg KOH / g. An acid value of 30–50 mg KOH / g or higher improves adhesion to the antistatic layer and adhesive layer, and is therefore preferred. On the other hand, an acid value of 50 mg KOH / g or lower maintains the water resistance of the coated layer after application, and the film is less prone to moisture absorption and adhesion, which is also preferred. However, to compensate for the water solubility or water dispersibility of the crosslinking agent in this invention, other hydrophilic groups, such as hydroxyl groups, ethers, sulfonic acids, phosphonic acids, quaternary ammonium compounds, etc., can be introduced within a range that does not degrade performance.

[0051] Examples of crosslinking agents containing carboxyl groups include oxazoline compounds, carbodiimide compounds, epoxy compounds, and isocyanate compounds, which introduce carboxyl groups into the molecule. Furthermore, to avoid intramolecular or intermolecular reactions with the carboxyl groups introduced into the molecule, the carboxyl groups can be pre-neutralized with a basic compound. Among these crosslinking agents, isocyanate compounds that readily introduce carboxyl groups into the molecule are preferred, and terminally capped isocyanate compounds are particularly preferred.

[0052] Examples of end-capping agents include sodium bisulfite and other bisulfite compounds, 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 methylene compounds such as dimethyl malonate and acetylacetone, thiols such as butyl mercaptan and dodecyl mercaptan, amides such as acetanilide and acetamide, lactams such as ε-caprolactam and δ-valerolactam, imides such as succinimide and maleimide, oximes such as acetaldehyde oxime, acetone oxime, and methyl ethyl ketone oxime, and amines such as diphenylaniline, aniline, and ethyleneimine.

[0053] The lower limit of the boiling point of the capping agent for the aforementioned capped isocyanate is preferably 150°C, more preferably 160°C, further preferably 180°C, particularly preferably 200°C, and most preferably 210°C. A higher boiling point of the capping agent helps to suppress the volatilization of the capping agent due to heating during the film preparation process and to suppress the formation of micro-unevennesses on the coating surface during the drying process after coating and in online coating methods, thus improving the transparency of the film. The upper limit of the boiling point of the capping agent is not particularly limited; from a productivity point of view, it is considered to be around 300°C. Since boiling point is related to molecular weight, it is preferable to use a capping agent with a large molecular weight to increase the boiling point. The molecular weight of the capping agent is preferably 50 or higher, more preferably 60 or higher, and even more preferably 80 or higher.

[0054] The upper limit of the dissociation temperature of the capping agent is preferably 200°C, more preferably 180°C, further preferably 160°C, particularly preferably 150°C, and most preferably 120°C. Regarding the capping agent, it dissociates through heating during the drying process after coating with the coating solution and during the film preparation process in the online coating method, regenerating isocyanate groups. Therefore, crosslinking reactions with urethane resins, etc., improve adhesion. When the dissociation temperature of the capping isocyanate is below the above-mentioned temperature, the dissociation of the capping agent is sufficient, thus improving adhesion, especially resistance to damp heat.

[0055] Examples of end-capping agents used in the end-capped isocyanates of this invention, having a dissociation temperature below 120°C and a boiling point above 150°C, include sodium bisulfite, 3,5-dimethylpyrazole, 3-methylpyrazole, dimethyl malonate, diethyl malonate, acetone oxime, and methyl ethyl ketone oxime. Among these, pyrazole compounds, represented by 3,5-dimethylpyrazole and 3-methylpyrazole, are preferred from the perspectives of resistance to damp heat and yellowing.

[0056] The aforementioned end-capped isocyanate is preferably 2-functional or higher, and from the viewpoint of the crosslinking properties of the coating film, end-capped isocyanates with 3-functional or higher are further preferred.

[0057] Polyisocyanates with three or more functions, which serve as precursors to the capped isocyanates of the present invention, can preferably be obtained by introducing isocyanate monomers. Examples include biuret bodies, isocyanurate bodies, and adducts obtained by modifying isocyanate monomers such as aromatic diisocyanates, aliphatic diisocyanates, aromatic aliphatic diisocyanates, or alicyclic diisocyanates having two isocyanate groups.

[0058] Biuret refers to a self-condensing compound with biuret bonds formed by the self-condensation of isocyanate monomers, such as the biuret of hexamethylene diisocyanate.

[0059] Isocyanurate esters refer to trimers of isocyanate monomers, such as trimers of hexamethylene diisocyanate, isophorone diisocyanate, and toluene diisocyanate.

[0060] An adduct is a compound with three or more functions, formed by reacting an isocyanate monomer with a compound containing low-molecular-weight active hydrogen. Examples include compounds obtained by reacting trimethylolpropane with hexamethylene diisocyanate, compounds obtained by reacting trimethylolpropane with toluene diisocyanate, compounds obtained by reacting trimethylolpropane with xylene diisocyanate, and compounds obtained by reacting trimethylolpropane with isophorone diisocyanate.

[0061] Examples of the aforementioned isocyanate monomers include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, 1,4-naphthalene diisocyanate, benzene diisocyanate, tetramethylphenyldimethylmethylene diisocyanate, 4,4'-diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, and 2,2'-diphenylpropane-4,4'-diisocyanate. Aromatic diisocyanates such as cyanate esters, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, 4,4'-diphenylpropane diisocyanate, 3,3'-dimethoxydiphenyl-4,4'-diisocyanate, and xylene diisocyanate; alicyclic diisocyanates such as isophorone diisocyanate and 4,4-dicyclohexylmethane diisocyanate; and aliphatic diisocyanates such as hexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate. From the perspectives of transparency, resistance to yellowing, adhesion, and resistance to damp heat, aliphatic and alicyclic isocyanates and their modifiers are preferred.

[0062] In this invention, other resins can be used in combination without affecting performance. Examples of resins that can be used in combination include carboxyl-free polyurethane, polyester resin, acrylic resin, cellulose resin, polyolefin resin, and polyacetal resin. Among these resins, polyester resin, which improves adhesion to the antistatic layer and adhesive layer when used in combination, is particularly preferred. Furthermore, when using polyester resin in combination, it can be at least 1.5 times higher than the total content of carboxyl-containing polyurethane resin and carboxyl-containing crosslinking agent. This effect is presumably because polyester resin has better affinity for the substrate (polyester resin) compared to carboxyl-containing polyurethane resin or carboxyl-containing crosslinking agent, and therefore tends to be confined to the substrate side in the thickness direction, thus improving adhesion to the substrate interface. The carboxyl-containing polyurethane resin and carboxyl-containing crosslinking agent, both confined to the surface layer, improve adhesion to the adhesive resin contained in the antistatic layer and adhesive layer, exhibiting a synergistic effect.

[0063] (Polyester resin)

[0064] The polyester resin used in the coating layer of the present invention can be a linear resin, and more preferably a polyester resin whose constituent components are dicarboxylic acids and diols (glycols) with branched structures. The dicarboxylic acids referred to herein include, in addition to terephthalic acid, isophthalic acid, or 2,6-naphthalenedicarboxylic acid, 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. In addition, branched diols refer to diols with branched alkyl groups, such as 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.

[0065] Regarding the aforementioned polyester resin, the more preferred embodiment is that the branched diol component is present in the total diol component at a rate of preferably 10 mol% or more, and more preferably 20 mol% or more. A rate of 10 mol% or more is preferred because it prevents excessive crystallinity and maintains the adhesion of the coating layer. The upper limit of the diol component in the total diol component is preferably 80 mol% or less, more preferably 70 mol% or less by mass. A rate of 80 mol% or less is preferred because it prevents an increase in the concentration of oligomers as byproducts and maintains the transparency of the coating layer. Ethylene glycol is most preferred as the diol component other than the aforementioned compound. Small amounts of diethylene glycol, propylene glycol, butanediol, hexanediol, or 1,4-cyclohexanediethanol may also be used.

[0066] Regarding the dicarboxylic acid that forms a component of the aforementioned polyester resin, terephthalic acid or isophthalic acid is most preferred. In addition to the aforementioned dicarboxylic acid, to impart water dispersibility to the copolyester resin, it is preferable to copolymerize 5-sulfonoisophthalic acid in the range of 1 to 10 mol%, examples of which include sulfonoterephthalic acid, 5-sulfonoisophthalic acid, and sodium 5-sulfonoisophthalate.

[0067] When the total solid components of the resin and crosslinking agent in the coating liquid forming the easy-to-adhere layer are set to 100% by mass, a polyester resin content of 10% by mass or more results in good adhesion between the easy-to-adhere layer and the polyester film substrate, which is preferred. The upper limit of the polyester resin content is preferably 65% ​​by mass or less, more preferably 60% by mass or less. A polyester resin content of 70% by mass or less results in good resistance to damp heat, which is also preferred.

[0068] In the easy-to-bond layer, resins other than the aforementioned polyester resins may also be used to a extent that does not degrade the performance of the product. A representative example of resins other than polyester resins is a polyurethane resin containing carboxyl groups; other resins may be included, or only a polyurethane resin containing carboxyl groups may be used.

[0069] At this point, when the total solid content of the resin and crosslinking agent in the coating liquid forming the easy-to-adhere layer is set to 100% by mass, the content of resin other than polyester resin is preferably 40% by mass or less, more preferably 30% by mass or less, and particularly preferably 20% by mass or less. However, the total content of resin other than polyester resin and polyester resin is preferably 70% by mass or less. The content of each of the polyurethane resin and crosslinking agent in the coating liquid forming the coating layer is preferably 3% by mass or more, calculated based on the total solid content of the resin and crosslinking agent.

[0070] When the content is 3% by mass or more, a good adhesion to the antistatic layer and adhesive layer can be obtained, which is preferred. A more preferred content range is 3.5% to 90% by mass, even more preferred is 7% to 80% by mass, and particularly preferred is 10.5% to 70% by mass.

[0071] (additive)

[0072] In the easily adhesive layer of this invention, 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 can be added to the layer without affecting the effect of this invention.

[0073] In this invention, adding particles to the coating layer to further improve its anti-blocking properties is also a preferred method. Examples of particles included in the coating layer in this invention include: titanium dioxide, barium sulfate, calcium carbonate, calcium sulfate, silica, alumina, talc, kaolin, clay, or mixtures thereof; inorganic particles used in combination with other common inorganic particles, such as calcium phosphate, mica, lithium montmorillonite, zirconium oxide, tungsten oxide, lithium fluoride, and calcium fluoride; and organic polymer particles such as styrene-based, acrylic-based, melamine-based, benzoguanamine-based, and organosilicon-based particles.

[0074] The average particle size (based on the number of particles observed by scanning electron microscopy (SEM), hereinafter the same) in the easy-to-adhere layer is preferably 0.04–2.0 μm, more preferably 0.1–1.0 μm. When the average particle size of the inert particles is 0.04 μm or more, it is easy to form unevenness on the film surface, thus improving the film's slip properties, roll-up properties, and other processability, and providing good processability during bonding, which is preferred. On the other hand, when the average particle size of the inert particles is 2.0 μm or less, the particles are less likely to detach, which is also preferred. Regarding the particle concentration in the easy-to-adhere layer, it is preferably 1–20% by mass in the solid composition.

[0075] The method for determining the average particle size is as follows: the cross-section of the laminate of polyester film substrate and easy-to-adhere layer (hereinafter also referred to as laminated polyester film) is observed using a scanning electron microscope, and 30 particles are observed and their average value is taken as the average particle size.

[0076] The shape of the particles is not particularly limited as long as the purpose of this invention is met; spherical particles and amorphous, non-spherical particles can be used. The particle size of amorphous particles can be calculated in the form of the equivalent diameter of a circle. The equivalent diameter of a circle is obtained by dividing the observed area of ​​the particle by π, calculating the square root, and multiplying by 2.

[0077] (Manufacturing of laminated polyester film)

[0078] Regarding the method for manufacturing the laminated polyester film of the present invention, examples of using polyethylene terephthalate (hereinafter sometimes simply referred to as PET) film substrates can be cited for illustration, but it is of course not limited thereto.

[0079] After the PET resin is thoroughly vacuum dried, it is fed to an extruder. Molten PET resin at approximately 280°C is extruded in sheet form from a T-die onto a rotating cooling roller. It is then cooled and cured using an electrostatic application method to obtain an unstretched PET sheet. This unstretched PET sheet can be a single layer or a multilayer structure based on a co-extrusion method.

[0080] Crystal orientation is achieved by subjecting the obtained unstretched PET sheet to uniaxial or biaxial stretching. For example, in biaxial stretching, the film is stretched 2.5 to 5.0 times its original length using rollers heated to 80–120°C to obtain a uniaxially stretched PET film. The ends of the film are then fixed with clamps and introduced into a hot air zone heated to 80–180°C, where it is stretched 2.5 to 5.0 times its original width. Alternatively, in uniaxial stretching, the film is stretched 2.5 to 5.0 times its original width in a tenter frame. After stretching, the film is further introduced into a heat treatment zone for heat treatment to complete crystal orientation.

[0081] 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, curing is sufficient, and the adhesion in the presence of liquid water becomes good, which is preferable, and there is no need to extend the drying time. On the other hand, the upper limit of the temperature in the heat treatment zone is preferably 250°C, more preferably 240°C. When the temperature in the heat treatment zone is below 240°C, there is no concern about a decrease in the physical properties of the film, which is preferable.

[0082] The easy-to-adhesion layer can be applied after film manufacturing or during the manufacturing process. From a productivity point of view, it is particularly preferable to form the easy-to-adhesion layer by applying a coating liquid to at least one side of the PET film after it has been unstretched or uniaxially stretched, stretching it at least along a uniaxial direction, and then heat-treating it at any stage of the film manufacturing process.

[0083] The method for applying the coating liquid to the PET film can be any known method. Examples include, for instance, reverse roller coating, gravure coating, lip coating, die coating, roller brush coating, spray coating, air knife coating, wire bar coating, tube doctor blade coating, dip coating, curtain coating, etc. These methods can be used individually or in combination.

[0084] The thickness of the easily bondable layer in this invention can be appropriately set within the range of 0.001 to 2.00 μm. To balance processability and adhesion, a range of 0.01 to 1.00 μm is preferred, more preferably 0.02 to 0.80 μm, and even more preferably 0.05 to 0.50 μm. A thickness of 0.001 μm or more of the easily bondable layer results in good adhesion and is preferred. A thickness of 2.00 μm or less of the easily bondable layer reduces the likelihood of adhesion and is also preferred.

[0085] The upper limit of haze of the laminated polyester film of the present invention is preferably 2.5%, more preferably 2.0%, further preferably 1.5%, and especially preferably 1.2%. A haze of 2.5% or less is preferred in terms of transparency and can be preferably used in optical films requiring transparency. Haze is generally preferred to be as low as possible, but is also preferably 0.1% or more, and even more preferably 0.2% or more.

[0086] (Antistatic layer)

[0087] The antistatic polyester film of the present invention has an antistatic layer on the easy-to-adhere layer of the laminated polyester film. The antistatic layer may be laminated on only one side or on both sides. By laminating the antistatic layer, when used as a protective film by laminating the adhesive layer, it is possible to suppress peeling static electricity or foreign matter adhesion to the adhered object, which is therefore preferred.

[0088] There are no particular limitations on the method of laminating the antistatic layer. Known methods such as coating, vacuum evaporation, and lamination can be used. From a cost point of view, it is more preferable to use coating to set the coating liquid containing the antistatic agent.

[0089] As antistatic agents, ion-conducting polymers such as cationic compounds, surfactants, silica films, conductive metal compounds, and π-electron conjugated conductive polymers can be used. From the viewpoint of antistatic performance under low humidity, π-electron conjugated conductive polymers are preferred. Furthermore, π-electron conjugated conductive polymers can maintain antistatic performance at a high level without depending on moisture in the air, thus exhibiting good antistatic performance in various application environments such as protective films, and are therefore preferred.

[0090] Examples of π-electron conjugated conductive polymers include aniline-based polymers containing aniline or its derivatives as structural units, pyrrole-based polymers containing pyrrole or its derivatives as structural units, acetylene-based polymers containing acetylene or its derivatives as structural units, and thiophene-based polymers containing thiophene or its derivatives as structural units. For high transparency, polymers without nitrogen atoms are preferred as π-electron conjugated conductive polymers. From a transparency perspective, thiophene-based polymers containing thiophene or its derivatives as structural units are preferred, and polyalkylene dioxythiophene is particularly preferred. Examples of polyalkylene dioxythiophene include polyethylene dioxythiophene, polypropylene dioxythiophene, and poly(ethylene / propylene) dioxythiophene.

[0091] It should be noted that in thiophene-based polymers containing thiophene or its derivatives as structural units, to improve antistatic properties, a dopant of 0.1 to 500 parts by mass can be added relative to, for example, 100 parts by mass of the polymer containing thiophene or its derivatives as structural units. Too little dopant hinders electron movement, thus reducing antistatic properties; conversely, too much dopant reduces solvent dispersibility. Examples of such dopants include LiCl and R... 1- 30 COOLi(R 1-30 : saturated hydrocarbon groups with 1 or more carbon atoms and less than 30 carbon atoms), R 1-30 SO3Li, R 1-30 COONa, R 1-30 SO3Na, R 1- 30 COOK, R 1-30 SO3K, tetraethylammonium, I2, BF3Na, BF4Na, HClO4, CF3SO3H, FeCl3, tetracyanoquinoline (TCNQ), Na2B 10 Cl 10 Phthalocyanine, porphyrin, glutamic acid, alkyl sulfonates, polystyrene sulfonate Na(K,Li) salt, styrene-styrene sulfonate Na(K,Li) salt copolymer, polystyrene sulfonate anion, styrene sulfonate-styrene sulfonate anion copolymer, etc.

[0092] In this invention, the antistatic agent contained in the antistatic layer preferably comprises 1% by mass or more, more preferably 10% by mass or more, relative to 100 parts by mass of the solid components of the antistatic layer. It should be noted that when using a π-electron conjugated system conductive polymer as the antistatic agent, and when using the aforementioned dopant, the content of the π-electron conjugated system conductive polymer in the antistatic layer specified in this application is the sum of the conductive polymer and the aforementioned dopant.

[0093] For example, the antistatic agent content can be less than 80% by mass, or less than 50% by mass.

[0094] The antistatic layer of the present invention preferably comprises an adhesive resin. The adhesive resin is not particularly limited, but specific examples of polymers include polyester resins, acrylic resins, urethane resins, polyolefin resins, polyvinyl alcohol resins (polyvinyl alcohol, etc.), polyalkylene glycols, polyalkylimides, methylcellulose, hydroxycellulose, starches, etc. Among these, polyester resins, acrylic resins, and urethane resins are preferred from the viewpoint of adhesion to the polyester film. Acrylic resins are further preferred from the perspective of ease of molecular design and molecular weight design.

[0095] The adhesive resin preferably also has reactive functional groups. Although not particularly limited, hydroxyl, carboxyl, amino, acrylate, epoxy, etc. are preferred, and hydroxyl and carboxyl groups are more preferred.

[0096] The aforementioned adhesive resin may contain silicone components, long-chain alkyl groups, or other components that exhibit release properties. When an adhesive layer is laminated, having an antistatic layer with release properties on the opposite side of the laminated film prevents adhesion even when wound into rolls, which is therefore preferable.

[0097] (Cross-linking agent)

[0098] In this invention, the antistatic layer can be formed by including a crosslinking agent to create a crosslinked structure. By containing a crosslinking agent, adhesion to easily bonded layers is improved, or durability is enhanced, and the decline in antistatic performance is suppressed even under high temperature and high humidity conditions; therefore, this is preferred. Specific crosslinking agents include urea-based, epoxy-based, melamine-based, isocyanate-based, oxazoline-based, carbodiimide-based, and aziridine-based agents. Melamine-based, oxazoline-based, carbodiimide-based, and aziridine-based agents are particularly preferred. Furthermore, catalysts can be used as needed to promote the crosslinking reaction.

[0099] The crosslinking agent contained in the antistatic layer of the present invention preferably comprises 5% by mass or more, more preferably 10% by mass or more, relative to 100 parts by mass of the solid components of the antistatic layer. When it is 5% by mass or more, the resistance of the antistatic layer to damp heat can be improved, and therefore it is preferred. Furthermore, when the crosslinking agent is self-crosslinking, it is possible to use a binder resin even without it. For example, the crosslinking agent can be 90% by mass or less, or even 80% by mass or less.

[0100] In the antistatic layer of this invention, surfactants can be used to improve the appearance. As surfactants, nonionic surfactants such as polyoxyethylene octylphenyl ether, polyoxyethylene alkyl ether, and polyoxyethylene sorbitan fatty acid ester, as well as fluorinated surfactants such as fluoroalkyl carboxylic acids, perfluoroalkyl carboxylic acids, perfluoroalkylbenzene sulfonic acids, perfluoroalkyl quaternary ammonium acids, and perfluoroalkyl polyoxyethylene ethanol, and organosilicon surfactants can be used.

[0101] In addition to the above, the antistatic layer may also contain lubricants, pigments, ultraviolet absorbers, silane coupling agents, etc., as needed, without hindering the purpose of the present invention.

[0102] The thickness of the antistatic layer of the present invention is preferably 0.005 μm or more and 1 μm or less. More preferably, it is 0.01 μm or more and 0.5 μm or less, and even more preferably, it is 0.01 μm or more and 0.2 μm or less. When the thickness of the antistatic layer is 0.005 μm or more, an antistatic effect can be obtained, which is preferred. On the other hand, when it is 1 μm or less, less coloring and higher transparency are achieved, which is also preferred.

[0103] The surface resistivity of the antistatic film of the present invention is preferably 1×10⁻⁶. 10 Ω / □ or less. Further preferred is 1×10⁻⁶. 9 Ω / □ or less, and more preferably 1×10 7 Ω / □ or less, especially preferably 1×10 6 Below Ω / □. By setting the surface resistivity to 1×10 10 A resistivity of Ω / □ or less can suppress the adhesion of foreign matter to the laminated polyester or suppress peeling static electricity during the lamination and peeling of the adhesive layer, and is therefore preferred. Furthermore, the lower limit of the surface resistivity of the antistatic film is not specifically specified, but is preferably 1×10⁻⁶. 3 Ω / □ or higher. To ensure the surface resistivity of the antistatic film is less than 1×10⁻⁶. 3 Ω / □ requires increasing the processing cost of the antistatic layer, therefore it is not preferred.

[0104] The haze of the antistatic film used in this invention is preferably 3% or less. More preferably, it is 1.5% or less, and even more preferably, it is 1.0% or less. Extremely preferably, it is 0.8% or less. When it is 3% or less, visual inspection can be performed while the protective film is bonded to the substrate, and therefore it is preferred, especially when the substrate is a component for optical applications.

[0105] The haze is preferably lower, which can be substantially 0% (or higher), for example, it can be 0.1% or higher.

[0106] The average surface roughness (Sa) of the antistatic film surface used in this invention is preferably in the range of 1 to 40 nm, more preferably 1 to 30 nm. Even more preferably, it is 1 to 10 nm. The maximum protrusion height (P) of the surface of the antistatic film used in this invention is preferably 2 μm or less, more preferably 1.5 μm or less. Even more preferably, it is 0.8 μm or less. When Sa is 40 nm or less and P is 2 μm or less, even when the adhesive layer is stacked and rolled into a roll, there is no need to worry about the adhesive surface becoming rough, which is preferable.

[0107] As a method for coating an antistatic layer onto the surface of a substrate film, there are methods such as gravure coating, reverse roller coating, air knife coating, dip coating, bar coating, and spin coating, in which a coating solution containing the aforementioned antistatic agent, binder resin, etc., is dispersed / dissolved in a solvent. The coating method suitable for conductive compositions is not particularly limited. Furthermore, the coating layer can be applied in an online coating process during film manufacturing or offlinely after film manufacturing.

[0108] Regarding the antistatic layer, the drying temperature for forming the antistatic layer by the above method is typically 60°C or higher and 150°C or lower, preferably 90°C or higher and 140°C or lower. From the viewpoint of enabling processing in a short time and improving productivity, this temperature of 60°C or higher is preferred. Furthermore, when a crosslinking agent is included, the crosslinking reaction proceeds sufficiently, which is therefore preferable. On the other hand, when the temperature is below 150°C, the planarity of the film is maintained, which is also preferable.

[0109] An adhesive layer can be laminated onto the antistatic film of the present invention by applying an adhesive and allowing it to cure. The adhesive can be used without particular limitation, and the resulting laminated film can be used as a protective film. The side on which the adhesive layer is laminated can be any side of the antistatic film. When using an antistatic film with an antistatic layer on only one side, it is preferable to have the antistatic layer on the side of the antistatic film opposite to the side with the laminated adhesive layer.

[0110] Example

[0111] 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 method used in the present invention will be described below.

[0112] (1) Haze

[0113] The haze of the obtained antistatic polyester film was measured using a turbidimeter (Nippon Denshoku Corporation, NDH5000) based on JIS K 7136:2000.

[0114] (2) Acid value

[0115] The acid value of the resin and crosslinking agent was determined by titration as described in JIS K1557-5:2007.

[0116] In the case of a carboxyl group that has been neutralized with an amine or the like, the measurement is carried out after removing the amine or the like by heat treatment or treating it in advance with hydrochloric acid or the like to make the amine or the like free and removed. Further, in the case of a crosslinking agent, the measurement is carried out after reacting reactive groups such as isocyanate with an amine or the like in advance. When the resin to be measured has poor solubility in isopropyl alcohol as a solvent, N-methylpyrrolidone can be used instead. Through any of the above treatments, the measurement for comparison can be fully carried out.

[0117] (3) Adhesion resistance

[0118] Overlap two film specimens with their coated surfaces facing each other, apply a load of 98 kPa, and allow them to bond in an atmosphere at 50 °C for 24 hours and then leave them standing. After that, peel off the films and judge the peeling state according to the following criteria.

[0119] ○: No transfer of the coating layer, and it can be peeled off gently.

[0120] △: The coating layer can be maintained, but the surface layer of the coating layer is partially transferred to the other side.

[0121] ×: The two films are adhered and cannot be peeled off, or even if they can be peeled off, the film substrate is split.

[0122] (4) Adhesion to the antistatic layer

[0123] For the antistatic layer laminated on the easy-bonding layer of the laminated polyester film, using a cutter guide with a gap of 2 mm, make 100 grid-shaped scratches on the antistatic layer surface that penetrate the antistatic layer and reach the film substrate. Then, stick a cellophane adhesive tape (Nichiban Co., Ltd., No. 405; 24 mm wide) on the grid-shaped scratch surface to make it firmly adhere. Then, vertically peel off the cellophane adhesive tape from the antistatic layer surface of the laminated film. After performing a total of 5 times of adhesive tape attachment and peeling operations at the same position, visually count the number of grids peeled off from the antistatic layer surface of the laminated film, and calculate the adhesion of the antistatic layer to the film substrate by the following formula. It should be noted that even if only part of a grid is peeled off, it is also counted as a peeled-off grid, and the adhesion of the antistatic layer is calculated as follows.

[0124] Adhesion of the antistatic layer (%) = 100 - (number of peeled-off grids)

[0125] Judge the adhesion of the antistatic layer according to the following criteria.

[0126] ◎: 100%, ○: 96 - 99%, △: 80 - 95%, ×: less than 80%

[0127] As a criterion, those with ○ or above are qualified.

[0128] (5) Damp heat resistance

[0129] For the antistatic polyester film with an antistatic layer, prepared in the same manner as described in (4) above, it was placed at 80°C and 80% RH for 500 hours with the coated surface perpendicular and not in contact with other films. After treatment, it was placed at 23°C and 65% RH for 10 minutes with the coated surface not in contact with other films. Immediately after the time elapsed, the adhesion of the coated surface was evaluated in the same manner as described above.

[0130] (6) Surface resistivity

[0131] Regarding the surface resistance value of the release film surface of the present invention, after conditioning for 24 hours at a temperature of 23°C and a humidity of 55%, the surface resistance value of the release layer surface was measured using a surface resistance meter (SIMCO JAPAN Worksurface Tester ST-3), and evaluated according to the following judgment criteria.

[0132] ◎: Surface resistivity less than 10 7 Ω / □

[0133] ○: Surface resistivity is 10 7 ~10 8 Ω / □

[0134] △: Surface resistivity is 10 9 ~10 10 Ω / □

[0135] ×: Surface resistivity is 10 11 Ω / □ and above

[0136] (Polymerization of polyurethane resin A-1)

[0137] To a four-necked flask equipped with a stirrer, a serpentine condenser, a nitrogen inlet tube, a silica gel drying tube, and a thermometer, 82.8 parts by weight of hydrogenated isophthalic diisocyanate, 25.0 parts by weight of dimethylolpropionic acid, 21.0 parts by weight of 1,6-hexanediol, 150.0 parts by weight of polyester glycol with a number average molecular weight of 2000 formed by adipic acid and 1,4-butanediol, and 110 parts by weight of acetone as a solvent were added. The mixture was stirred at 75°C for 3 hours under a nitrogen atmosphere to confirm that the reaction solution had reached the specified amine equivalent. Then, the reaction solution was cooled to 40°C, and 19.8 parts by weight of triethylamine were added to obtain a polyurethane polymer solution. Then, 500 g of water was added to a reaction vessel equipped with a high-speed homogenizer, the temperature was adjusted to 25°C, and the mixture was stirred at a high speed for 2000 min. -1Aqueous dispersion was achieved by adding a polyurethane polymer solution while stirring and mixing. Then, acetone, used as a solvent, was removed under reduced pressure. The concentration was adjusted with water to prepare a solution containing 35% by mass of the solids component of polyurethane resin (A-1) with an acid value of 37.5 mg KOH / g.

[0138] (Polymerization of polyurethane resin A-2)

[0139] To a four-necked flask equipped with a stirrer, a serpentine condenser, a nitrogen inlet tube, a silica gel drying tube, and a thermometer, 63.0 parts by weight of hydrogenated isophthalic diisocyanate, 21.0 parts by weight of dimethylolpropionic acid, 147.0 parts by weight of polycarbonate diol (1,6-hexanediol type) with a number average molecular weight of 2000, and 110 parts by weight of acetone as a solvent were added. The mixture was stirred at 75°C for 3 hours under a nitrogen atmosphere to confirm that the reaction solution had reached the specified amine equivalent. Then, the reaction solution was cooled to 40°C, and 16.6 parts by weight of triethylamine were added to obtain a polyurethane polymer solution. Next, 500 g of water was added to a reaction vessel equipped with a high-speed homogenizer, the temperature was adjusted to 25°C, and the mixture was stirred at a high speed for 2000 min. -1 Aqueous dispersion was achieved by adding a polyurethane polymer solution while stirring and mixing. Then, acetone, used as a solvent, was removed under reduced pressure. The concentration was adjusted with water to prepare a solution containing 35% by mass of the solids component of polyurethane resin (A-2) with an acid value of 36.3 mg KOH / g.

[0140] (Polymerization of polyurethane resin A-3)

[0141] To a four-necked flask equipped with a stirrer, a serpentine condenser, a nitrogen inlet tube, a silica gel drying tube, and a thermometer, 64.5 parts by weight of hydrogenated diphenylmethane diisocyanate, 21.5 parts by weight of dimethylolpropionic acid, 11.2 parts by weight of neopentyl glycol, 150.5 parts by weight of polycarbonate diol (1,6-hexanediol type) with a number average molecular weight of 2000, and 110 parts by weight of acetone as a solvent were added. The mixture was stirred at 75°C for 3 hours under a nitrogen atmosphere to confirm that the reaction solution had reached the specified amine equivalent. Then, the reaction solution was cooled to 40°C, and 17.0 parts by weight of triethylamine were added to obtain a polyurethane polymer solution. Next, 500 g of water was added to a reaction vessel equipped with a high-speed homogenizer, the temperature was adjusted to 25°C, and the mixture was stirred at a high speed for 2000 min. -1 Aqueous dispersion was achieved by adding a polyurethane polymer solution while stirring and mixing. Then, acetone, used as a solvent, was removed under reduced pressure. The concentration was adjusted with water to prepare a solution containing 35% by mass of the solids component of polyurethane resin (A-3) with an acid value of 36.0 mg KOH / g.

[0142] (Polymerization of polyurethane resin A-4)

[0143] To a four-necked flask equipped with a stirrer, a serpentine condenser, a nitrogen inlet tube, a silica gel drying tube, and a thermometer, 83.4 parts by weight of hydrogenated isophthalic acid diisocyanate, 16.9 parts by weight of dimethylolpropionic acid, 28.4 parts by weight of 1,6-hexanediol, 151.0 parts by weight of polyester glycol with a number average molecular weight of 2000 formed by adipic acid and 1,4-butanediol, and 110 parts by weight of acetone as a solvent were added. The mixture was stirred at 75°C for 3 hours under a nitrogen atmosphere to confirm that the reaction solution had reached the specified amine equivalent. Then, the reaction solution was cooled to 40°C, and 13.3 parts by weight of triethylamine were added to obtain a polyurethane polymer solution. Next, 500 g of water was added to a reaction vessel equipped with a high-speed homogenizer, the temperature was adjusted to 25°C, and the mixture was stirred at a high speed for 2000 min. -1 Aqueous dispersion was achieved by adding a polyurethane polymer solution while stirring and mixing. Then, acetone, used as a solvent, was removed under reduced pressure. The concentration was adjusted with water to prepare a polyurethane resin (A-4) solution with a solid content of 35% by mass and an acid value of 25.3 mg KOH / g.

[0144] (Polymerization of polyurethane resin A-5)

[0145] To a four-necked flask equipped with a stirrer, a serpentine condenser, a nitrogen inlet tube, a silica gel drying tube, and a thermometer, 104.9 parts by weight of hydrogenated isophthalic diisocyanate, 41.8 parts by weight of dimethylolpropionic acid, 19.0 parts by weight of 1,6-hexanediol, 152.0 parts by weight of polyester glycol with a number average molecular weight of 2000 formed by adipic acid and 1,4-butanediol, and 110 parts by weight of acetone as a solvent were added. The mixture was stirred at 75°C for 3 hours under a nitrogen atmosphere to confirm that the reaction solution had reached the specified amine equivalent. Then, the reaction solution was cooled to 40°C, and 33.1 parts by weight of triethylamine were added to obtain a polyurethane polymer solution. Next, 500 g of water was added to a reaction vessel equipped with a high-speed homogenizer, the temperature was adjusted to 25°C, and the mixture was stirred at a high speed for 2000 min. -1 Aqueous dispersion was achieved by adding a polyurethane polymer solution while stirring and mixing. Then, acetone, used as a solvent, was removed under reduced pressure. The concentration was adjusted with water to prepare a polyurethane resin (A-5) solution with a solid content of 35% by mass and an acid value of 55.0 mg KOH / g. A solution containing 35% by mass of polyurethane resin (A-5) with an acid value of 55.0 mg KOH / g was prepared.

[0146] (Polymerization of polyurethane resin A-6)

[0147] To a four-necked flask equipped with a stirrer, a serpentine condenser, a nitrogen inlet tube, a silica gel drying tube, and a thermometer, 45.0 parts by weight of hydrogenated isophthalic diisocyanate, 20.0 parts by weight of 1,6-hexanediol, 149.0 parts by weight of polyethylene glycol with a number average molecular weight of 2000, and 110 parts by weight of acetone as a solvent were added. The mixture was stirred at 75°C for 3 hours under a nitrogen atmosphere to confirm that the reaction solution had reached the specified amine equivalent. Then, the reaction solution was cooled to 40°C, and 500 g of water was added to a reaction vessel equipped with a high-speed homogenizer. The temperature was adjusted to 25°C, and the mixture was stirred at a high speed for 2000 min. -1 Aqueous dispersion was achieved by adding a polyurethane polymer solution while stirring and mixing. Then, acetone, used as a solvent, was removed under reduced pressure. The concentration was adjusted with water to prepare a solution containing 35% by mass of the solids component of polyurethane resin (A-6) with an acid value of 0.2 mg KOH / g.

[0148] (Polymerization of polyurethane resin A-7)

[0149] To a four-necked flask equipped with a stirrer, a serpentine condenser, a nitrogen inlet tube, a silica gel drying tube, and a thermometer, 43.8 parts by weight of hydrogenated diphenylmethane diisocyanate, 12.9 parts by weight of dimethylolbutyric acid, 153.4 parts by weight of polycarbonate diol (1,6-hexanediol type) with a number average molecular weight of 2000, and 110 parts by weight of acetone as a solvent were added. The mixture was stirred at 75°C for 3 hours under a nitrogen atmosphere to confirm that the reaction solution had reached the specified amine equivalent. Then, the reaction solution was cooled to 40°C, and 8.8 parts by weight of triethylamine were added to obtain a polyurethane polymer solution. Next, 500 g of water was added to a reaction vessel equipped with a high-speed homogenizer, the temperature was adjusted to 25°C, and the mixture was stirred at a high speed for 2000 min. -1 Aqueous dispersion was achieved by adding a polyurethane polymer solution while stirring and mixing. Then, acetone, used as a solvent, was removed under reduced pressure. The concentration was adjusted with water to prepare a polyurethane resin (A-7) solution with a solid content of 35% by mass and an acid value of 23.1 mg KOH / g. A solution containing 35% by mass of polyurethane resin (A-7) with an acid value of 23.1 mg KOH / g was prepared.

[0150] (Synthesis of crosslinking agent B-1)

[0151] To a flask equipped with a stirrer, thermometer, and reflux condenser, 59.5 parts by mass of hexamethylene diisocyanate, 10.7 parts by mass of neopentyl glycol, 11.0 parts by mass of dimethylolbutyric acid, and 20.0 parts by mass of N-methylpyrrolidone as a solvent were added. The mixture was stirred at 80°C for 3 hours under a nitrogen atmosphere to confirm that the reaction solution reached the specified amine equivalent. Then, 29.9 parts by mass of 2-butanone oxime were added dropwise to the reaction solution, and the mixture was kept at 80°C for 1 hour under a nitrogen atmosphere. After measuring the infrared spectrum of the reaction solution and confirming that the absorption of the isocyanate groups had disappeared, the reaction solution was cooled to 40°C, and 7.9 parts by mass of triethylamine were added. After stirring directly for 1 hour, an appropriate amount of water was added to prepare a 40% by mass solution of end-capped isocyanate-based crosslinking agent (B-1). The acid value of crosslinking agent B-1, based on the solid content, was 37.6 mg KOH / g.

[0152] (Synthesis of crosslinking agent B-2)

[0153] In a flask equipped with a stirrer, thermometer, and reflux condenser, 66.6 parts by weight of a polyisocyanate compound (Asahi Kasei Chemicals, Durnate TPA) with an isocyanurate structure, based on hexamethylene diisocyanate, and 17.5 parts by weight of N-methylpyrrolidone were added dropwise. The mixture was kept at 70°C for 1 hour under a nitrogen atmosphere. Then, 9.0 parts by weight of dimethylolpropionic acid were added dropwise. The infrared spectrum of the reaction solution was measured, and after confirming the disappearance of the isocyanate group absorption, 6.3 parts by weight of N,N-dimethylethanolamine was added. After stirring directly for 1 hour, an appropriate amount of water was added, thus preparing a 40% by weight solution of end-capped isocyanate-based crosslinking agent (B-2). The acid value of crosslinking agent B-2, based on its solid content, was 41.2 mg KOH / g.

[0154] (Synthesis of crosslinking agent B-3)

[0155] To a flask equipped with a stirrer, thermometer, and reflux condenser, 150.0 parts by weight of water and 250.0 parts by weight of methoxypropanol were added, and the mixture was heated to 80°C under a nitrogen atmosphere. Then, under a nitrogen atmosphere and while maintaining the flask at 80°C, a polymerization initiator solution consisting of a monomer mixture of 126.0 parts by weight of methyl methacrylate, 210.0 parts by weight of 2-isopropenyl-2-oxazoline, and 53.0 parts by weight of triethylamine methacrylate, along with 18.0 parts by weight of 2,2'-azobis(2-amidinepropane) dihydrochloride and 170.0 parts by weight of water as the polymerization initiator, was added dropwise over 2 hours. After the addition was complete, 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 a 40% by weight oxazoline-based crosslinking agent (B-3) solution. The acid value of crosslinking agent B-3, based on the solids content, was 39.8 mg KOH / g.

[0156] (Polymerization of crosslinking agent B-4)

[0157] To a flask equipped with a stirrer, thermometer, and reflux condenser, add 65.0 parts by weight of a polyisocyanate compound (Asahi Kasei Chemicals, Durnate TPA) with an isocyanurate structure based on hexamethylene diisocyanate, 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 with a number average molecular weight of 500. Maintain the mixture at 70°C for 2 hours under a nitrogen atmosphere. Then, add 4.0 parts by weight of trimethylolpropane dropwise. Measure the infrared spectrum of the reaction solution. After confirming the disappearance of the isocyanate group absorption, add 280.0 parts by weight of water. Add an appropriate amount of water to prepare a 40% by weight solution of end-capped polyisocyanate crosslinking agent (B-4). The acid value of crosslinking agent B-4, based on its solid content, is 0.0 mg KOH / g.

[0158] (Polymerization of crosslinking agent B-5)

[0159] In a flask equipped with a stirrer, thermometer, and reflux condenser, 66.04 parts by weight of a polyisocyanate compound (Asahi Kasei Chemicals, Durnate TPA) with an isocyanurate structure, based on hexamethylene diisocyanate, and 17.50 parts by weight of N-methylpyrrolidone were added dropwise. The mixture was kept at 70°C for 1 hour under a nitrogen atmosphere. Then, 5.27 parts by weight of dimethylolpropionic acid were added dropwise. The infrared spectrum of the reaction solution was measured, and after confirming the disappearance of the isocyanate group absorption, 5.59 parts by weight of N,N-dimethylethanolamine and 132.5 parts by weight of water were added. A suitable amount of water was added to prepare a 40% by weight solution of a capped polyisocyanate-based crosslinking agent (B-5). The acid value of crosslinking agent B-5, based on its solid content, was 22.8 mg KOH / g.

[0160] (Synthesis of crosslinking agent B-6)

[0161] To a flask equipped with a stirrer, thermometer, and reflux condenser, 59.5 parts by mass of hexamethylene diisocyanate, 6.8 parts by mass of neopentyl glycol, 16.6 parts by mass of dimethylolbutyric acid, and 20.0 parts by mass of N-methylpyrrolidone as a solvent were added. The mixture was stirred at 80°C for 3 hours under a nitrogen atmosphere to confirm that the reaction solution had reached the specified amine equivalent. Then, 30.3 parts by mass of 2-butanone oxime were added dropwise to the reaction solution, and the mixture was kept at 80°C for 1 hour under a nitrogen atmosphere. After measuring the infrared spectrum of the reaction solution and confirming that the absorption of the isocyanate groups had disappeared, the reaction solution was cooled to 40°C, and 11.9 parts by mass of triethylamine were added. After stirring directly for 1 hour, an appropriate amount of water was added to prepare a 40% by mass solution of end-capped isocyanate-based crosslinking agent (B-6). The acid value of crosslinking agent B-6, based on the solid content, was 55.4 mg KOH / g.

[0162] (Manufacturing of polyester resin C-1)

[0163] 194.2 parts by weight of dimethyl terephthalate, 184.5 parts by weight of dimethyl isophthalate, 14.8 parts by weight of sodium 5-sulfoisophthalate, 233.5 parts by weight of diethylene glycol, 136.6 parts by weight of ethylene glycol, and 0.2 parts by weight of tetrabutyl titanate were added to a stainless steel autoclave equipped with a stirrer, thermometer, and partial reflux condenser. The transesterification reaction was carried out at 160°C to 220°C for 4 hours. The temperature was then raised to 255°C, and the reaction system was slowly reduced in pressure, followed by a reaction under reduced pressure of 30 Pa for 1 hour and 30 minutes to obtain a copolyester resin (CR-1). The obtained copolyester resin (CR-1) was pale yellow and transparent. The specific viscosity of the copolyester resin (CR-1) was measured and found to be 0.70 dl / g.

[0164] 15 parts by weight of copolyester resin (CR-1) and 15 parts by weight of ethylene glycol n-butyl ether were added to a reactor equipped with a stirrer, thermometer, and reflux device. The mixture was heated and stirred at 110°C to dissolve the resin. After the resin was completely dissolved, 70 parts by weight of water were slowly added to the polyester solution while stirring. The solution was then cooled to room temperature while stirring. With the addition of an appropriate amount of water, a polyester resin (C-1) solution with a solid content of 30% by weight was prepared. The acid value of polyester resin C-1, based on the solid content, was 0.9 mg KOH / g.

[0165] (Manufacturing of polyester resin C-2)

[0166] 194.2 parts by mass of dimethyl terephthalate, 194.2 parts by mass of dimethyl isophthalate, 233.5 parts by mass of diethylene glycol, 136.6 parts by mass of ethylene glycol, and 0.2 parts by mass of tetrabutyl titanate were added to a stainless steel autoclave equipped with a stirrer, thermometer, and partial reflux condenser. The transesterification reaction was carried out at 160°C to 220°C for 4 hours. The temperature was then raised to 255°C, and the reaction system was slowly depressurized, reacting for 1 hour under a reduced pressure of 30 Pa. Nitrogen gas was then introduced into the system, the depressurization was released, and the system was cooled to 200°C. 28.0 parts by mass of trimellitic anhydride were added to the system under stirring, and an addition reaction was carried out for another 2 hours to obtain a copolyester resin (CR-2). The obtained copolyester resin (CR-2) was pale yellow and transparent. The specific viscosity of the copolyester resin (CR-2) was measured to be 0.35 dl / g.

[0167] 15 parts by mass of copolyester resin (CR-2) and 15 parts by mass of tetrahydrofuran were added to a reactor equipped with a stirrer, thermometer, and reflux device. The mixture was heated to 70°C and stirred until the resin dissolved. After the resin was completely dissolved, 31 parts by mass of triethylamine and 70 parts by mass of water were slowly added to the polyester solution under stirring. After the addition, the system was depressurized to remove the tetrahydrofuran and cooled to room temperature. An appropriate amount of water was added to prepare a polyester resin (C-2) solution C-2 with a solid content of 30% by mass. The acid value of polyester resin C-2 based on the solid content was 37.4 mg KOH / g.

[0168] (Manufacturing of acrylic resin D-1)

[0169] To a flask equipped with a stirrer, thermometer, and reflux condenser, 40 parts of propylene glycol monomethyl ether were added. The mixture was heated to 100°C and maintained thereafter. Over 3 hours, a mixture of 60.0 parts by weight of n-butyl acrylate, 42.0 parts by weight of methyl methacrylate, 2.9 parts by weight of hydroxyethyl methacrylate, 5.7 parts by weight of acrylic acid, and 5 parts by weight of azobisisobutyronitrile (AIB) was added dropwise. After the addition, the mixture was allowed to mature at this temperature for 2 hours. The reaction solution was then cooled to 40°C, and while stirring, 8.4 parts by weight of triethylamine and 165 parts by weight of water were added. After stirring directly for 1 hour, an appropriate amount of water was added, thus preparing an acrylic resin (D-1) solution with a solid content of 35% by weight. The acid value of this acrylic resin D-1, based on its solid content, was 40.1 mg KOH / g.

[0170] (Manufacturing of acrylic resin D-2)

[0171] Add 231 parts by mass of methyl methacrylate (MMA), 130 parts by mass of stearate methacrylate (SMA), 100 parts by mass of hydroxyethyl methacrylate (HEMA), 33 parts by mass of methacrylic acid (MAA), and 1153 parts by mass of isopropanol (IPA) to a four-necked flask equipped with a stirrer, reflux condenser, thermometer, and nitrogen purge tube. While stirring, heat the flask to 80°C. Maintain the flask at 80°C and stir for 3 hours. Then add 0.5 parts by mass of 2,2-azobis-2-methyl-N-2-hydroxyethylpropionamide to the flask. While heating the flask to 120°C and purging with nitrogen, stir the mixture at 120°C for 2 hours.

[0172] Next, unreacted raw materials and solvents were removed by a reduced pressure of 1.5 kPa at 120°C, yielding an acrylic resin containing long-chain alkyl groups. The pressure in the flask was restored to atmospheric pressure, cooled to room temperature, and 1592 parts by mass of an IPA aqueous solution (50% by mass) was added and mixed. Then, while stirring, ammonia was added using a dropping funnel to neutralize the acrylic resin containing long-chain alkyl groups, adjusting the pH of the solution to a range of 5.5–7.5, resulting in a 20% by mass solution of acrylic resin containing long-chain alkyl groups (D-2). The acid value of this acrylic resin (D-2) based on its solids content was 104 mg KOH / g.

[0173] (Manufacturing of polyester resin E-1 for substrate)

[0174] (Preparation of antimony trioxide solution)

[0175] Antimony trioxide (manufactured by Sigma-Aldrich Japan) was added to a flask along with ethylene glycol. The mixture was stirred at 150°C for 4 hours until dissolved, and then cooled to room temperature to prepare a 20 g / L antimony trioxide ethylene glycol solution.

[0176] (Polymerization of polyester resin E-1 for substrate)

[0177] In a 2-liter stainless steel autoclave equipped with a stirrer, high-purity terephthalic acid and twice the molar amount of ethylene glycol were added, along with triethylamine at 0.3 mol% relative to the acid content. The mixture was subjected to an esterification reaction at 250°C under a pressure of 0.25 MPa, while simultaneously removing water by distillation, to obtain a mixture of bis(2-hydroxyethyl) terephthalate and oligomers with an esterification rate of approximately 95% (hereinafter referred to as the BHET mixture). In this BHET mixture, the aforementioned antimony trioxide solution was used as a polycondensation catalyst, added at 0.04 mol% (based on antimony atoms) relative to the acid content in the polyester. The mixture was then stirred for 10 minutes at 250°C under a nitrogen atmosphere and atmospheric pressure. Then, the temperature was raised to 280°C over 60 minutes, and the pressure of the reaction system was slowly reduced to 13.3 Pa (0.1 Torr). Further, a polycondensation reaction was carried out at 280°C and 13.3 Pa for 68 minutes to obtain polyester resin E-1 with an intrinsic viscosity (IV) (solvent: phenol / tetrachloroethane = 60 / 40) of 0.61 dl / , which is substantially free of particles.

[0178] (Manufacturing of polyester resin E-2 for substrate)

[0179] (Example of aluminum compound solution preparation)

[0180] An equal volume of ethylene glycol was added to a flask along with a 20 g / L aqueous solution of basic aluminum acetate (aluminum diacetate; manufactured by Sigma-Aldrich Japan). After stirring at room temperature for 6 hours, water was distilled off the system under reduced pressure (133 Pa) at 70–90 °C for several hours to prepare an ethylene glycol solution of the aluminum compound at a concentration of 20 g / L.

[0181] (Example of preparation of phosphorus compound solution)

[0182] Diethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate (Irganox 1222 (manufactured by BASF)) as a phosphorus compound was added to a flask along with ethylene glycol. The mixture was heated at 160°C for 25 hours under nitrogen purging with stirring to prepare an ethylene glycol solution of the phosphorus compound with a concentration of 50 g / L.

[0183] (Preparation of a mixture of solutions of aluminum compounds and solutions of phosphorus compounds)

[0184] The ethylene glycol solutions obtained in the above-mentioned aluminum compound preparation example and the above-mentioned phosphorus compound preparation example were added to a flask and mixed at room temperature with an aluminum atom to phosphorus atom molar ratio of 1:2. The mixture was stirred for 1 day to prepare a catalyst solution.

[0185] (Polymerization of polyester resin E-2 for substrate)

[0186] As a polycondensation catalyst, a mixture of the above-mentioned aluminum compound solution and phosphorus compound solution was used instead of the antimony trioxide solution, and added in such a manner that the acid content in the polyester was 0.014 mol% and 0.028 mol% respectively, based on aluminum atoms and phosphorus atoms. Otherwise, polymerization was carried out in the same manner as polyester resin E-1. The polymerization time was set to 68 minutes, thereby obtaining polyester resin E-2 with an intrinsic viscosity (IV) of 0.61 dl / and substantially free of particles.

[0187] (Example 1)

[0188] (1) Preparation of coating solution

[0189] Mix the following coating agent into a mixed solvent of water and isopropanol (80 / 20 by mass ratio) to prepare a coating liquid for forming an easy-to-adhere layer with a solid component mass ratio of 70 / 30 for polyurethane resin (A-1) solution / crosslinking agent (B-1) solution.

[0190]

[0191]

[0192] (2) Manufacturing of laminated polyester film

[0193] As a polymer feedstock for the film, polyester resin E-1 granules were dried at 135°C for 6 hours under reduced pressure of 133 Pa. The dried granules were then fed to an extruder and melt-extruded into sheets at approximately 280°C. The sheets were then rapidly cooled and solidified on a rotating cooling metal roller with a surface temperature maintained at 20°C to obtain unstretched PET sheets.

[0194] The unstretched PET sheet is heated to 100°C using a heated roller assembly and an infrared heater, and then stretched 3.5 times along its length using a roller assembly with a circumferential speed difference to obtain a uniaxially stretched PET film.

[0195] Next, the coating liquid was dried to a final coating weight of 0.13 g / m². 2 The coating solution was applied to one side of a PET film. After drying, the film was stretched 4.0 times its original width at 110°C, and then heated at 230°C for 5 seconds while keeping the width direction of the film fixed. A 3% relaxation treatment in the width direction was then performed to obtain a laminated polyester film with a 100μm easy-to-adhere layer.

[0196] 3. Manufacturing of antistatic polyester film

[0197] On the easily bondable layer of the obtained laminated polyester film, a coating amount of 0.08 g / m² after drying is applied. 2The following coating liquid (AS-1) was applied in the manner described. After coating, it was dried / cured by heating with hot air at 140°C for 20 seconds to obtain a laminated polyester film with an antistatic layer (antistatic polyester film). Various physical properties and evaluation results are shown in Tables 1 and 2.

[0198] It should be noted that the abbreviation "AS" in the table refers to antistatic.

[0199] (AS-1)

[0200]

[0201]

[0202] (Example 2)

[0203] The polyurethane resin was designated as (A-2), and the ratio of polyurethane resin to crosslinking agent was changed to 60 / 40 (mass ratio). Otherwise, the process was carried out in the same manner as in Example 1 to obtain an antistatic polyester film.

[0204] (Example 3)

[0205] The polyurethane resin was set as (A-3), and the ratio of polyurethane resin to crosslinking agent was changed to 50 / 50 (mass ratio). Otherwise, the process was carried out in the same manner as in Example 1 to obtain an antistatic polyester film.

[0206] (Example 4)

[0207] The crosslinking agent was set to (B-2), and the ratio of polyurethane resin to crosslinking agent was changed to 60 / 40 (mass ratio). Otherwise, the process was carried out in the same manner as in Example 1 to obtain an antistatic polyester film.

[0208] (Example 5)

[0209] The crosslinking agent was set to (B-3), and the ratio of polyurethane resin to crosslinking agent was changed to 60 / 40 (mass ratio). Otherwise, the process was carried out in the same manner as in Example 1 to obtain an antistatic polyester film.

[0210] (Example 6)

[0211] In addition to polyurethane resin (A-1) and crosslinking agent (B-1), crosslinking agent (B-4) is also used in combination, and the ratio is changed to (A-1) / (B-1) / (B-4) = 55 / 35 / 10 (mass ratio). Otherwise, it is carried out in the same manner as in Example 1 to obtain an antistatic polyester film.

[0212] (Example 7)

[0213] In addition to polyurethane resin (A-1) and crosslinking agent (B-1), polyester resin (C-1) is also used in combination, and the ratio is changed to (A-1) / (B-1) / (C-1) = 36 / 24 / 40 (mass ratio). Otherwise, it is carried out in the same manner as in Example 1 to obtain an antistatic polyester film.

[0214] (Example 8)

[0215] In addition to polyurethane resin (A-1) and crosslinking agent (B-1), polyester resin (C-1) is also used in combination, and the ratio is changed to (A-1) / (B-1) / (C-1) = 24 / 16 / 60 (mass ratio). Otherwise, it is carried out in the same manner as in Example 1 to obtain an antistatic polyester film.

[0216] (Example 9)

[0217] Using polyester resin granules of E-2 as the membrane raw material polymer, the process was otherwise the same as in Example 1 to obtain an antistatic polyester film.

[0218] (Example 10)

[0219] The coating liquid for the antistatic layer was changed to AS-2, and the process was otherwise the same as in Example 1 to obtain an antistatic polyester film.

[0220] (AS-2)

[0221]

[0222] (Example 11)

[0223] The coating liquid for the antistatic layer was changed to AS-3, and the process was otherwise the same as in Example 1 to obtain an antistatic polyester film.

[0224] (AS-3)

[0225]

[0226] (Example 12)

[0227] The coating liquid for the antistatic layer was changed to AS-4, and the process was otherwise the same as in Example 1 to obtain an antistatic polyester film.

[0228] (AS-4)

[0229]

[0230] (Comparative Example 1)

[0231] Using only polyurethane resin (A-1) and without crosslinking agent (B-1), the process was carried out in the same manner as in Example 1 to obtain an antistatic polyester film.

[0232] (Comparative Example 2)

[0233] Using only the crosslinking agent (B-1) and without the polyurethane resin (A-1), the process was carried out in the same manner as in Example 1 to obtain an antistatic polyester film.

[0234] (Comparative Example 3)

[0235] The polyurethane resin was set to (A-4), and the process was otherwise carried out in the same manner as in Example 1 to obtain an antistatic polyester film.

[0236] (Comparative Example 4)

[0237] The polyurethane resin was set as (A-5), and the ratio of polyurethane resin to crosslinking agent was changed to 60 / 40 (mass ratio). Otherwise, the process was carried out in the same manner as in Example 1 to obtain an antistatic polyester film.

[0238] (Comparative Example 5)

[0239] The polyurethane resin was set as (A-6), and the ratio of polyurethane resin to crosslinking agent was changed to 50 / 50 (mass ratio). Otherwise, the process was carried out in the same manner as in Example 1 to obtain an antistatic polyester film.

[0240] (Comparative Example 6)

[0241] The polyurethane resin was changed to (A-7), the crosslinking agent was changed to (B-5), and the process was otherwise the same as in Example 1 to obtain an antistatic polyester film.

[0242] (Comparative Example 7)

[0243] The crosslinking agent was set to (B-5), and the ratio of polyurethane resin to crosslinking agent was changed to 75 / 25 (mass ratio). Otherwise, the process was carried out in the same manner as in Example 1 to obtain an antistatic polyester film.

[0244] (Comparative Example 8)

[0245] The crosslinking agent was changed to (B-6), and the process was otherwise the same as in Example 1 to obtain an antistatic polyester film.

[0246] (Comparative Example 9)

[0247] The polyurethane resin (A-1) was replaced with polyester resin (C-2), and the process was otherwise carried out in the same manner as in Example 1 to obtain an antistatic polyester film.

[0248] (Comparative Example 10)

[0249] The polyurethane resin (A-1) was replaced with an acrylic resin (D-1), and the process was otherwise carried out in the same manner as in Example 1 to obtain an antistatic polyester film.

[0250] The various physical properties and evaluation results of each embodiment and comparative example are summarized in Tables 1 and 2.

[0251] As shown in Table 2, satisfactory results were obtained in each embodiment in terms of haze, anti-adhesion, adhesion to the antistatic layer, and resistance to damp heat. On the other hand, in Comparative Examples 1 to 10, at least one of the above evaluation items was unsatisfactory.

[0252] [Table 1]

[0253]

[0254] [Table 2]

[0255]

[0256] The antistatic polyester film of the present invention comprises, in sequence, the easy-adhesion layer and the antistatic layer of the present invention. In particular, by having the easy-adhesion layer of the present invention, an antistatic polyester film with excellent anti-adhesion properties, excellent initial adhesion between the antistatic layer and the easy-adhesion layer and the polyester film substrate, and excellent resistance to damp heat adhesion can be provided.

[0257] On the other hand, Comparative Example 1 does not contain the crosslinking agent of the present invention, and therefore has significantly poor resistance to damp heat and tightness. Comparative Example 2 does not contain the polyurethane resin of the present invention, and therefore has significantly poor resistance to damp heat and tightness. The acid value of the polyurethane resin in Comparative Example 3 is outside the range of the present invention, and therefore has significantly poor resistance to damp heat and tightness. The acid value of the polyurethane resin in Comparative Example 4 is outside the range of the present invention, and therefore has poor resistance to damp heat and tightness. The polyurethane resin in Comparative Example 5 has substantially no acid value, and therefore has significantly poor resistance to adhesion and resistance to damp heat and tightness. The acid values ​​of the polyurethane resin and crosslinking agent in Comparative Example 6 are outside the range of the present invention, and therefore have significantly poor resistance to damp heat and tightness. The acid value of the crosslinking agent in Comparative Example 7 is outside the range of the present invention, and therefore has significantly poor resistance to damp heat and tightness. The acid value of the crosslinking agent in Comparative Example 8 is outside the range of the present invention, and therefore has poor resistance to damp heat and tightness. Comparative Examples 9 and 10 are examples in which polyester resin (Comparative Example 9) or acrylic resin (Comparative Example 10) is used instead of the polyurethane resin of the present invention. The acid values ​​of the polyester or acrylic resins used are within the same range as those of the polyurethane resin of this invention. However, in the case of these resins, the result is significantly poor resistance to humid heat and poor adhesion.

[0258] Industrial availability

[0259] According to the present invention, an antistatic polyester film suitable for all applications such as optical use, packaging use, and labeling use can be provided.

Claims

1. An antistatic polyester film, characterized in that, An easy-to-adhesion layer and an antistatic layer are sequentially laminated on at least one side of a polyester film. The easy-to-adhesion layer is a layer formed by curing a composition comprising a polyurethane resin having carboxyl groups and an acid value of 30-50 mg KOH / g and a crosslinking agent having carboxyl groups and an acid value of 30-50 mg KOH / g. The polyurethane resin having carboxyl groups and the crosslinking agent having carboxyl groups are in a weight ratio of 70 / 30 to 30 / 70. The crosslinking agent is an isocyanate-based crosslinking agent or an oxazoline-based crosslinking agent. The antistatic agent contained in the antistatic layer is a π-electron conjugated system conductive polymer.

2. The antistatic polyester film according to claim 1, wherein, The crosslinking agent is an isocyanate compound.

3. The antistatic polyester film according to claim 1 or 2, characterized in that, The surface resistivity is 10 10 Below Ω / □.

4. The antistatic polyester film according to claim 1 or 2, characterized in that, The membrane haze is below 3.0%.

5. An adhesive film having an adhesive layer laminated on at least one side of the antistatic polyester film according to any one of claims 1 to 4.

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