White laminated polyester film

Abstract

[Problem] To provide a laminated white polyester film having adhesion of a coating layer to a base material layer, adhesion to UV ink, sealability, and writing properties.[Means for solving the problem] A white laminated polyester film having a coating layer formed of a coating layer forming composition containing a thermosetting resin composition (A), inorganic particles (B), and a functional resin composition (C) on at least one surface of a white polyester resin layer, wherein the thermosetting resin composition (A) contains a urethane resin having at least a polycarbonate structure and a branch structure, and the content of the urethane resin having the polycarbonate structure and the branch structure is 4% by mass or more and 12% by mass or less based on 100% by mass of the total solid content of the coating layer forming composition.

Description

Technical Field

[0001] This invention relates to a white laminated polyester film useful as various labels, cards, delivery slips, printer paper, etc., and to a white laminated polyester film having properties of coating adhesion to coatings, adhesion to UV inks, stamping and writing properties. Background Technology

[0002] Compared to natural paper, white laminated polyester film not only has superior water resistance, moisture absorption dimensional stability, flatness, gloss and clarity of printed materials, but also superior mechanical strength. Therefore, as a synthetic paper to replace natural paper, it is widely used in fields such as packaging paper, labels, maps, posters, business cards and other cards, delivery slips, and recording paper for various printers.

[0003] For example, Patent Document 1 discloses a toner-based printing material having a toner-adhesive layer on a substrate layer. Patent Document 2 discloses a recording material having a writing layer on a substrate layer and a writable protective layer on that writing layer.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2005-246750

[0007] Patent Document 2: Japanese Patent Application Publication No. 2003-345051 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] In the material described in Patent Document 1, a porous material is used to impart writeability. However, the writing layer made of a porous material is brittle and tends to be easily erased.

[0010] In the toner-adhesive recording material shown in Patent Document 2, a large amount of resin component is used to improve the adhesion of the toner. However, if a large amount of resin component is used, there is a tendency for reduced stampability and writeability.

[0011] In addition, in recent years, the applications of white laminated polyester films have become more widespread, requiring stampability, writability, and adhesion to various inks and toners. For example, if the recorded material shown in Patent Document 1 is used for printing purposes, the writing layer is brittle, and the adhesion to the substrate layer may be weakened, potentially leading to poor adhesion due to cohesion failure between the writing layer and the substrate layer or within the writing layer itself.

[0012] When the toner shown in Patent Document 2 is used for stamping and writing, it is easy for the ink to bleed due to the low porosity of the material. This may result in ink smudging on the back of the ink and stains on the adhesive surface in the next operation.

[0013] This invention was made against the backdrop of such prior art issues. Specifically, the object of this invention is to provide a laminated white polyester film that possesses properties such as adhesion of the coating layer to the substrate layer, adhesion to UV ink, stamping ability, and writing ability.

[0014] Solution for solving the problem

[0015] That is, the present invention comprises the following components.

[0016] [1] A white laminated polyester film having a coating layer formed from a coating layer forming composition comprising a thermosetting resin composition (A), inorganic particles (B), and a functional resin composition (C) on at least one side of a white polyester resin layer, wherein the thermosetting resin composition (A) comprises at least a urethane resin having a polycarbonate structure and a branched structure, and

[0017] In the total solid components of the above-mentioned coating layer forming composition, the content of the urethane resin having a polycarbonate structure and a branched structure is 4% or more and 12% or less.

[0018] [2] In one method, the inorganic particles (B) include two or more particles (B1) with an average particle size of 0.1 μm or more and less than 1.0 μm and particles (B2) with an average particle size of 1.0 μm or more and less than 10.0 μm, the mixing amount of B1 and B2 has the following relationship, B1 / B2 = 0.1 or more and 4.0 or less, and the content of inorganic particles (B) in the total solid components of the coating layer is 30% by mass or more and 70% by mass or less.

[0019] [3] In one embodiment, the functional resin composition (C) is a compound comprising at least one selected from polyester resin, acrylic-styrene copolymer resin, and polymeric antistatic agent.

[0020] [4] In one embodiment, the styrene resin is a resin having at least a sulfonate.

[0021] [5] In one embodiment, the sulfonate is an alkali metal sulfonate.

[0022] [6] In one embodiment, the surface resistivity (logΩ / □) of the coated layer of the white laminated polyester film at 23°C and 65%RH is 13 or less.

[0023] The effects of the invention

[0024] The white laminated polyester film of the present invention can improve the adhesion of the coating layer to the substrate layer and improve the adhesion of the coating layer to inks, such as UV inks. In addition, it can have excellent stamping and writing properties. Detailed Implementation

[0025] The present invention will now be described in detail.

[0026] This invention relates to a white laminated polyester film, wherein at least one side of the white polyester resin layer has a coating layer formed by a coating layer forming composition comprising a thermosetting resin composition (A), inorganic particles (B), and a functional resin composition (C), wherein the thermosetting resin composition (A) contains at least a urethane resin having a polycarbonate structure and a branched structure, and

[0027] Of the total solid components of the coating layer forming composition, the content of the urethane resin having a polycarbonate structure and a branched structure is 4% or more and 12% or less.

[0028] According to the present invention, excellent writeability can be imparted to the recorded material. For example, during writing, damage caused by pressure from writing instruments and surface collapse can be suppressed. Furthermore, it exhibits excellent abrasion resistance. Moreover, it can suppress ink bleeding during stamping, and prevent ink from smudging on the back and easily adhered surfaces during stamping and writing operations, thus providing excellent stamping and writing properties. In addition to exhibiting excellent writeability for various writing instruments such as ballpoint pens and pencils, the written text can remain for a long time.

[0029] In addition to satisfying the requirements of stampability, writingability, and adhesion to various inks and toners, the present invention also exhibits excellent adhesion between the coating layer and the substrate, and can suppress the damage of the coating layer itself.

[0030] (White polyester resin layer)

[0031] The white polyester resin layer of the present invention can be, for example, a polyester resin layer.

[0032] In this invention, the polyester resin constituting the polyester resin layer (sometimes also referred to as the polyester film substrate) is polyethylene terephthalate, polybutylene terephthalate, polyethylene 2,6-naphthalenedicarboxylate, polypropylene terephthalate, etc., and 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 can be included; dicarboxylic acid components such as adipic acid, sebacic acid, phthalic acid, isophthalic acid, sodium isophthalate-5-sulfonate, and 2,6-naphthalenedicarboxylic acid can be included; etc.

[0033] 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 from the perspective of balancing physical properties and cost. Furthermore, the polyester film substrate composed of these polyester resins is preferably a biaxially oriented polyester film, which can improve chemical resistance, heat resistance, and mechanical strength.

[0034] The catalyst used for polycondensation in the manufacture of polyester resin is not particularly limited; antimony trioxide is a suitable catalyst as it is inexpensive and exhibits excellent catalytic activity. Additionally, germanium or titanium compounds are preferred. Further 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.

[0035] From the perspective of practicality, such as strength and toughness, the polyester film used in this invention is particularly preferably a biaxially oriented film.

[0036] The polyester film substrate can have a single-layer structure or a multilayer structure, specifically an A / B / A layer multilayer structure. A preferred embodiment is a multilayer structure where layer A contains inorganic particles and layer B contains micropores. By configuring layer A, which serves as the surface layer, to contain inorganic particles, the film's slip properties (handleability) and opacity can be improved. By containing micropores only in layer B, which serves as the inner layer, the film's cushioning properties can be maintained while ensuring surface strength. The method of forming the multilayer structure is not particularly limited; however, co-extrusion is preferred from the perspective of manufacturing stability and processing costs.

[0037] Furthermore, the polyester film used as the white polyester resin layer in this invention can be a single-layer structure or a multi-layer structure, and preferably, some or all of its layers are opaque. The optical density representing the opacity of the polyester film is 0.3 or more, preferably 0.3 or more and 4.0 or less, and particularly preferably 0.5 or more and 3.0 or less. If the optical density is less than 0.3, the printing effect becomes unclear when printing is performed on the surface of the obtained polyester film, which is undesirable. Conversely, if the optical density is 4.0 or less, a better printing effect can be expected.

[0038] The method for obtaining the optical density within the aforementioned range is not particularly limited, and can be achieved by containing inorganic particles or a thermoplastic resin incompatible with the polyester resin in the polyester resin. These contents are not particularly limited, but in the case of inorganic particles, the content is preferably 5% by mass or more and 35% by mass or less, particularly preferably 8% by mass or more and 25% by mass or less, relative to the generated polyester. On the other hand, in the case of containing an incompatible thermoplastic resin, the content is preferably 5% by mass or more and 35% by mass or less, particularly preferably 8% by mass or more and 28% by mass or less, relative to the polyester. Furthermore, in the case of using both inorganic particles and a thermoplastic resin incompatible with the polyester resin, from the perspective of film strength, toughness, and film formation stability, the combined content relative to the polyester film is preferably 40% by mass or less.

[0039] The inorganic particles that may be included in the white polyester resin layer are not particularly limited, but inorganic particles with an average particle size of 0.1 to 4.0 μm are preferred, and inorganic particles with an average particle size of 0.3 to 1.5 μm are particularly preferred. Specifically, white pigments such as titanium dioxide, barium sulfate, calcium carbonate, and zinc sulfide are preferred, and they may also be mixed. Furthermore, inorganic particles commonly found in films, such as silica, alumina, talc, kaolin, clay, calcium phosphate, mica, lithium montmorillonite, zirconium oxide, tungsten oxide, lithium fluoride, calcium fluoride, and calcium sulfate, may also be used.

[0040] Furthermore, there are no particular limitations on the thermoplastic resins that are incompatible with polyester resins. Examples of thermoplastic resins that can be mixed with polyethylene terephthalate resins include polystyrene resins, polyethylene resins, polypropylene resins, polymethylpentene resins, and other polyolefin resins; acrylic resins, phenoxy resins, polyphenylene ether resins, polycarbonate resins, etc. These thermoplastic resins can be mixed or modified. They can also be used in combination with the aforementioned inorganic particles. Additionally, various whitening agents can be added as needed.

[0041] Furthermore, the polyester film used in this invention preferably has an apparent density of 0.3 g / cm³. 3 Above and 1.3g / cm 3 The following are polyester films containing micro-voids.

[0042] From the perspective of balancing buffering and surface peel strength, polyester films containing micro-voids with a void stack density of 0.20 voids / μm or more, preferably 0.25 voids / μm or more, and more preferably 0.30 voids / μm or more are preferred. As a result, the obtained polyester cover film exhibits excellent print clarity and processing characteristics during printing. Here, the void stack density (voids / μm) is defined by the formula: number of voids in the film thickness direction (voids) / film thickness (μm). From the perspective of void performance efficiency, the upper limit of this void stack density is preferably 0.80 voids / μm or less, and more preferably 0.55 voids / μm or less. As a method to adjust this density to the above range, in addition to adjusting the amount, type, viscosity, etc. of the incompatible thermoplastic resin, methods such as changing the screw shape of the extruder and setting a static mixer in the molten resin flow path can also be used, but are not limited to these methods.

[0043] These polyester films containing micropores exhibit light scattering at the interface between the micropores in the film and the polyester matrix, thereby further increasing opacity and reducing the addition of the aforementioned inorganic particles, making them particularly useful. Furthermore, the presence of micropores allows for a lighter substrate film, facilitating processing and resulting in greater economic benefits such as reduced raw material and transportation costs.

[0044] As a method for obtaining such a polyester film containing micro-voids, a known method can be used: for the thermoplastic polyester resin as the matrix, as described above, a thermoplastic resin incompatible with the polyester resin is compounded, and the film is stretched at least along the uniaxial direction to disperse the incompatible resin in the polyester resin in the form of microparticles, thereby creating voids around the microparticles of the incompatible resin.

[0045] Furthermore, the thickness of the obtained polyester film containing micro-voids is preferably 5 to 300 μm. In particular, the thickness of the polyester film containing micro-voids with a void stacking density of 0.20 voids / μm or more is preferably 20 to 300 μm, and more preferably 40 to 250 μm.

[0046] The required whiteness for printing materials can be expressed using color values. Specifically, the L value (lightness index) is a measure of brightness; a higher value indicates whiter whiteness. Furthermore, a high b value results in a stronger yellow tint, while a low value results in a stronger blue tint. In other words, a high L value and a low b value indicate high whiteness, resulting in a stronger visual perception of whiteness. This improves clarity during printing.

[0047] To improve adhesion to the coating layer, a corona treatment layer and / or an easy-adhesion layer can be provided on the surface of the substrate film, which serves as the white polyester resin layer. As a method for forming the easy-adhesion layer, a coating method is typically employed. Specifically, gravure coating, kiss coating, immersion coating, spray coating, curtain coating, air knife coating, doctor blade coating, and reverse roller coating can be used. Regarding the timing of coating, any method can be employed, such as coating before film stretching, coating after longitudinal stretching, or coating on the film surface after orientation treatment. However, the most preferred method for improving coating adhesion is the following in-line coating method: after applying the coating liquid to at least one surface of the substrate film stretched along a uniaxial direction using the above-described coating method, it is then stretched in a direction perpendicular to the previous uniaxial stretching method.

[0048] The resin used in the easy-to-bond layer preferably contains one, two, or three of the following: acrylic, polyester, and urethane compositions. If necessary, the coating composition for the easy-to-bond layer may also contain a crosslinking agent.

[0049] (Coating layer)

[0050] The coating layer of the present invention is a layer laminated on at least one side of a white polyester resin layer, comprising a coating layer forming composition containing a thermosetting resin composition (A), inorganic particles (B), and a functional resin composition (C). By having the coating layer of the present invention, the laminated polyester film of the present invention can possess all the properties of adhesion to the white polyester resin layer (substrate layer), adhesion to UV ink, stamping properties, and writing properties.

[0051] Furthermore, the thermosetting resin composition (A) contains at least a urethane resin having a polycarbonate structure and a branched structure, and the content of the urethane resin having a polycarbonate structure and a branched structure is 4% or more and 12% or less of the total solid components of the coating layer forming composition in 100% by mass.

[0052] The coating layer is considered to be formed by the cross-linking of a thermosetting resin composition (A), inorganic particles (B), and a functional resin composition (C) with a cross-linking agent and then curing. However, since it is difficult to represent the chemical structure of the cross-linking itself, it is presented as a coating layer forming composition containing thermosetting resin composition (A), inorganic particles (B), and functional resin composition (C) being cured. The coating layer can be provided on both sides of the polyester film, or it can be provided on only one side of the polyester film, with different types of resin covering layers provided on the other side.

[0053] The coating layer forming composition will be described in detail below.

[0054] (Thermosetting resin composition (A))

[0055] The thermosetting resin composition (A) comprises a urethane resin having at least a polycarbonate structure and a branched structure. By having such a thermosetting resin composition (A), the adhesion of the coating layer to the substrate layer can be improved, and the adhesion of the coating layer to ink, such as UV ink, can be improved. Furthermore, it exhibits excellent stamping and writing properties.

[0056] The urethane resin used in this invention preferably has urethane bond portions and branched structures derived from polycarbonate polyol and polyisocyanate components, and further includes chain extenders as needed. The branched structure referred to herein is a structure preferably introduced by the presence of three or more terminal functional groups in any of the aforementioned raw material components constituting the molecular chain, forming a branched molecular chain structure after synthesis and polymerization.

[0057] For the urethane resin with a polycarbonate structure in this invention, the lower limit of the number of terminal functional groups in the molecular chain is preferably 3, and more preferably 4, depending on its branching structure. If there are 3 or more, the coating strength of the coating layer can be improved. For the urethane resin with a polycarbonate structure in this invention, the upper limit of the number of terminal functional groups in the molecular chain is preferably 6, depending on its branching structure. If there are 6 or fewer, the resin can be stably dispersed in an aqueous solution, which is therefore preferred. Since the resin can be dispersed in an aqueous solution, the environmental burden can be reduced.

[0058] The lower limit of the mass ratio (mass of polycarbonate polyol to polyisocyanate component) of the urethane resin with a polycarbonate structure in the synthesis and polymerization of the present invention is preferably 0.5, more preferably 0.6, further preferably 0.7, particularly preferably 0.8, and most preferably 1.0. A ratio of 0.5 or higher improves the adhesion to UV inks, and is therefore preferred. The upper limit of the mass ratio of polycarbonate polyol to polyisocyanate component in the synthesis and polymerization of the urethane resin with a polycarbonate structure in the present invention is preferably 3.0, more preferably 2.2, further preferably 2.0, particularly preferably 1.7, and most preferably 1.5. A ratio of 3.0 or lower improves the coating strength of the coating layer, and is therefore preferred.

[0059] The polycarbonate polyol component used for synthesizing and polymerizing the urethane resin with a polycarbonate structure of the present invention preferably contains an aliphatic polycarbonate polyol with excellent heat resistance and hydrolysis resistance. 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 for synthesizing and polymerizing the urethane resin with a polycarbonate structure of the present invention include aliphatic polycarbonate diols obtained by reacting one or more of the following 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, neopentanediol, diethylene glycol, and dipropylene glycol—with carbonates such as dimethyl carbonate, ethylene carbonate, and phosgene.

[0060] The number average molecular weight of the polycarbonate polyol used in this invention is preferably 1000 or more and 3000 or less. More preferably, it is 1200 or more and 2900 or less, and most preferably, it is 1500 or more and 2800 or less. If it is 1000 or more, the ink adhesion can be improved, so it is preferred. If it is 3000 or less, the coating strength of the coating layer can be improved, and damage caused by pressure from writing instruments can be suppressed.

[0061] Examples of polyisocyanates used for synthesizing and polymerizing the polycarbonate-structured urethane resins of this invention include aromatic aliphatic diisocyanates such as diphenylmethylene diisocyanate, isophorone diisocyanate and 4,4-dicyclohexylmethane diisocyanate, 1,3-bis(isocyanate-methyl)cyclohexane, hexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate, or polyisocyanates obtained by prior addition of one or more of these compounds with trimethylolpropane, etc. When using the above-mentioned aromatic aliphatic diisocyanates, aliphatic diisocyanates, or aliphatic diisocyanates, there is no problem with yellowing, which is preferable. Furthermore, the coating film is not too hard, which can alleviate the stress caused by the thermal shrinkage of the polyester film substrate, resulting in good adhesion, which is also preferable.

[0062] 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; thiodiols such as thiodiethylene glycol; or water.

[0063] In order to form a branched structure in urethane resin, for example, it is preferable to use the following method: after setting an appropriate temperature and time to react the above-mentioned polycarbonate polyol components, polyisocyanates, and chain extenders, add a compound having hydroxyl or isocyanate groups with more than 3 functions to further carry out the reaction.

[0064] Specific examples of compounds having three or more hydroxyl groups include caprolactone triol, glycerol, trimethylolpropane, glycerol, hexanetriol, 1,2,3-hexanetriol, 1,2,3-pentanetriol, 1,3,4-hexanetriol, 1,3,4-pentanetriol, 1,3,5-hexanetriol, 1,3,5-pentanetriol, and polyether triols. As for the aforementioned polyether triols, examples include compounds obtained by addition polymerization of one or more monomers such as ethylene oxide, propylene oxide, butane oxide, pentane oxide, glycidyl ether, methyl glycidyl ether, tert-butyl glycidyl ether, and phenyl glycidyl ether, using one or more of these compounds having three active hydrogens as initiators.

[0065] Specific examples of compounds having three or more isocyanate groups include polyisocyanate compounds having at least three isocyanate (NCO) groups in one molecule. In this invention, isocyanate compounds with three or more functions can include biuret bodies, ureate esters, and adducts formed by modifying isocyanate monomers such as aromatic diisocyanates, aliphatic diisocyanates, aromatic aliphatic diisocyanates, and alicyclic diisocyanates having two isocyanate groups.

[0066] Examples of aromatic diisocyanates include 1,3-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-toluidine diisocyanate, bianisidine diisocyanate, and 4,4'-diphenyl ether diisocyanate.

[0067] Examples of aliphatic diisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylidene diisocyanate, 2,3-butylidene diisocyanate, 1,3-butylidene diisocyanate, dodecamethyl diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

[0068] Examples of aromatic aliphatic diisocyanates include phenyl diisocyanate, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,4-tetramethylphenyl diisocyanate, and 1,3-tetramethylphenyl diisocyanate.

[0069] Alicyclic diisocyanates include, for example, 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (also known as IPDI, isophorone diisocyanate), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), and 1,4-bis(isocyanate methyl)cyclohexane, etc.

[0070] Biuret is a self-condensing compound that has a biuret bond formed by the self-condensation of isocyanate monomers. Examples of biuret are hexamethylene diisocyanate.

[0071] Urea esters are trimers of isocyanate monomers, such as trimers of hexamethylene diisocyanate, isophorone diisocyanate, and toluene diisocyanate.

[0072] An adduct is an isocyanate compound with three or more functions, formed by reacting the above-mentioned isocyanate monomer with a low-molecular-weight compound containing 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 phenylenediamine diisocyanate, and compounds obtained by reacting trimethylolpropane with isophorone diisocyanate.

[0073] As chain extenders having three or more functional groups, the description of the above chain extenders includes alcohols such as trimethylolpropane and pentaerythritol, which have three or more hydroxyl groups.

[0074] To impart water dispersibility to urethane resins, (copolymerized) sulfonic acid (salt) groups or carboxylic acid (salt) groups can be introduced into the urethane molecular backbone. To maintain moisture resistance, weakly acidic carboxylic acid (salt) groups are preferred. Alternatively, nonionic groups such as polyoxyalkylene groups can also be introduced.

[0075] To introduce carboxylic acid (salt) groups into urethane resins, polyol compounds containing carboxylic acid groups, such as dimethylolpropionic acid and dimethylolbutyric acid, are introduced as copolymerizing components and neutralized by a salt-forming agent. Specific examples of salt-forming agents include trialkylamines such as ammonia, trimethylamine, triethylamine, triisopropylamine, tri-n-propylamine, and tri-n-butylamine; N-alkylmorpholines such as N-methylmorpholine and N-ethylmorpholine; and N-dialkylalkanolamines such as N-dimethylethanolamine and N-diethylethanolamine. These can be used alone or in combination of two or more.

[0076] To impart water dispersibility, when using a polyol compound with a carboxylic acid (salt) group as the copolymer component, and setting the total polyisocyanate content of the urethane resin to 100 mol%, the molar ratio of the polyol compound with a carboxylic acid (salt) group in the urethane resin is preferably 3 mol% or more and 60 mol% or less, and more preferably 5 mol% or more and 40 mol% or less. A molar ratio of 3 mol% or more provides good water dispersibility and is preferred. Furthermore, a molar ratio of 60 mol% or less maintains water resistance and provides resistance to damp heat, which is also preferred.

[0077] To improve rigidity, the urethane resin of the present invention preferably has an end-capped isocyanate structure. The end-capped isocyanate structure may be included in the branched structure.

[0078] The lower limit of the boiling point of the isocyanate-terminated sealing agent at the end of the urethane resin 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 sealing agent better suppresses the volatilization of the sealing agent due to heating during the drying process after coating and during the film-forming process in online coating methods, and better suppresses the formation of minor unevenness on the coated surface. The upper limit of the boiling point of the sealing agent is not particularly limited; from a productivity perspective, it is considered to be around 300°C. Boiling point is related to molecular weight; therefore, to increase the boiling point of the sealing agent, it is preferable to use a sealing agent with a large molecular weight. The molecular weight of the sealing agent is preferably 50 or higher, more preferably 60 or higher, and further preferably 80 or higher.

[0079] The upper limit of the dissociation temperature of the capping agent is preferably 180°C, more preferably 160°C, further preferably 150°C, and most preferably 120°C. During the drying process after coating with the coating solution, and during the film-forming process in online coating methods, the capping agent dissociates from its functional groups due to heating, generating regenerated isocyanate groups. Therefore, the crosslinking reaction proceeds, and the adhesion is improved. When the dissociation temperature of the capping isocyanate is below the above-mentioned temperature, the dissociation of the capping agent is sufficient, thus the adhesion, especially the resistance to damp heat, becomes good.

[0080] Examples of end-capping agents for the isocyanate used in this invention, having a dissociation temperature of 120°C or lower and a boiling point of 150°C or higher, include bisulfite compounds such as sodium bisulfite; pyrazole compounds such as 3,5-dimethylpyrazole, 3-methylpyrazole, 4-bromo-3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole; active methylene compounds such as malonate (dimethyl malonate, diethyl malonate, di-n-butyl malonate, di-2-ethylhexyl malonate), methyl ethyl ketone, etc.; and triazole compounds such as 1,2,4-triazole. Among these, pyrazole compounds are preferred from the perspectives of resistance to damp heat and yellowing.

[0081] The urethane resin having a polycarbonate structure and a branched structure contains 4% to 12% by mass of the total solids content of the coating layer forming composition within 100% by mass. Preferably, it contains 4.5% to 11.5% by mass, more preferably 5% to 11% by mass. If it contains 4% or more by mass, the adhesion to UV inks and the hardness of the coating layer become good. Furthermore, if it is 12% or less by mass, the adhesion to the substrate film and the sealing properties are improved, which is preferred.

[0082] In particular, by including a urethane resin with a polycarbonate structure and a branched structure within this range, the coating layer can achieve film strength that can withstand various writing forms, thereby suppressing bleeding during stamping and inhibiting ink smudging on the back and stains on easily adhesive surfaces during stamping and writing operations.

[0083] Furthermore, the thermosetting resin composition (A) used in combination with a urethane resin having a polycarbonate structure and a branched structure may include thermosetting acrylic resins, oxazoline compounds, melamine compounds, carbodiimide compounds, epoxy resins, ester resins, alkyd resins, and urethane resins other than the aforementioned urethane resins. From the perspective of improving surface hardness, acrylic resins, oxazoline compounds, melamine compounds, and carbodiimide compounds are preferred. Acrylic resins, oxazoline compounds, melamine compounds, and carbodiimide compounds are preferred, oxazoline compounds, melamine compounds, and carbodiimide compounds are particularly preferred, and melamine compounds are most preferred.

[0084] Examples of thermosetting acrylic resins include, but are not limited to, resins having hydroxyl, hydroxymethyl, hydroxyethyl, hydroxybutyl, alkoxymethyl, alkoxyethyl, alkoxybutyl, epoxy, imino, etc., in the main chain and / or side chains.

[0085] Thermosetting oxazoline compounds refer to compounds containing an oxazoline group within their molecules. Polymers containing an oxazoline group are particularly preferred and can be prepared by addition-polymerizable monomers containing an oxazoline group, either alone or in combination with other monomers. Examples of addition-polymerizable monomers containing an oxazoline group include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, and 2-isopropenyl-5-ethyl-2-oxazoline. One or a mixture of two or more of these monomers can be used. Among these, 2-isopropenyl-2-oxazoline is readily available industrially and is preferred. There are no restrictions on other monomers as long as they can copolymerize with monomers containing oxazoline groups that are capable of addition polymerization. Examples include (meth)acrylates such as alkyl methacrylates (where the alkyl group is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, 2-ethylhexyl, cyclohexyl); unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, styrene sulfonic acid and their salts (sodium salt, potassium salt, ammonium salt, tertiary amine salt, etc.); unsaturated nitriles such as acrylonitrile and methacrylonitrile; and (meth)acrylamide, N-alkyl (meth)acrylamide, N... The monomers used include N-dialkyl (methyl)acrylamide and unsaturated amides (as alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, 2-ethylhexyl, cyclohexyl, etc.); vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; α-olefins such as ethylene and propylene; halogenated α,β-unsaturated monomers such as vinyl chloride and vinylidene chloride; and α,β-unsaturated aromatic monomers such as styrene and α-methylstyrene. One or more of these monomers can be used, and catalysts can also be used to improve reactivity.

[0086] The aforementioned melamine compounds refer to compounds having a melamine backbone. Examples of suitable compounds include alkylated melamine derivatives, compounds partially or completely etherified by reacting an alcohol with an alkylated melamine derivative, and mixtures thereof. Methanol, ethanol, isopropanol, n-butanol, and isobutanol are preferred alcohols used in etherification. Furthermore, the melamine compound can be any of a monomer or a polymer of two or more monomers, or a mixture thereof. Additionally, substances formed by co-condensing urea or the like in a portion of melamine can be used, and catalysts can be used to enhance the reactivity of the melamine compound.

[0087] Thermosetting carbodiimide compounds can be synthesized using existing known techniques, generally through the condensation reaction of diisocyanate compounds. There are no particular limitations on the diisocyanate compounds used; both aromatic and aliphatic compounds can be employed. Specifically, examples include toluene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, dicyclohexyl diisocyanate, and dicyclohexylmethane diisocyanate. Catalysts can also be used to enhance reactivity.

[0088] The thermosetting resin composition (A) described above preferably contains 4% to 27% by mass of the total solid components of the coating layer forming composition out of 100% by mass. If it is 4% by mass or more, the inorganic particles will not detach, which is preferred. Furthermore, if it is 4% by mass or more, the coating layer cures sufficiently and has good abrasion resistance. If it is 27% or less, adhesion to the substrate film is maintained, which is also preferred.

[0089] (Inorganic particles (B))

[0090] Examples of inorganic particles (B) used as the surface coating layer in this invention include silica, kaolin, talc, calcium carbonate, zeolite, alumina, barium sulfate, carbon black, zinc oxide, and titanium oxide, but these are not limited to these. Among them, silica and calcium carbonate are particularly preferred.

[0091] These inorganic particles are preferably a combination of two or more types of particles (B1) with an average particle size of 0.1 μm or more and less than 1.0 μm, and particles (B2) with an average particle size of 1.0 μm or more and less than 10.0 μm. By combining particles within the above range, the surface roughness and maximum protrusion height of the coating layer can be adjusted to the desired range.

[0092] As for the mass ratio of B1 to B2, it is preferable that B1 / B2 = 0.1 or more and 4.0 or less, and more preferably B1 / B2 = 0.2 or more and 3.5 or less. If B1 / B2 is within the range of 0.1 or more and 4.0 or less, the surface roughness and maximum protrusion height are adjusted to the desired range, resulting in good stamping and writing properties. Furthermore, if B1 / B2 is within the range of 0.2 or more and 3.5 or less, stamping and writing properties can be more clearly identified. There are no particular limitations on the shape of the particles used; any of the following can be used: spherical, blocky, rod-shaped, flat, etc. There are also no particular limitations on their hardness, specific gravity, color, etc.

[0093] It should not be limited to a specific theory for explanation, but by maintaining the mass ratio of B1 to B2 within this range, for example, unlike films formed solely of resin, insufficient strength can be compensated for by using particles. Furthermore, during writing, it can suppress breakage and surface collapse caused by pressure from writing instruments. Consequently, it exhibits excellent abrasion resistance.

[0094] In one approach, the mass ratio of B1 to B2 can be greater than 1.0 and less than 4.0, or greater than 1.0 and less than 3.5. By making the amount of particles (B1) greater than the amount of particles (B2), good writeability can be imparted to the recorded material.

[0095] While not limited to a specific theory, maintaining a B1 to B2 mass ratio within this range allows for faster ink drying and bonding. For example, it better suppresses ink bleeding during stamping, and reduces ink smudging on the back of the inkpad and stains on easily adhered surfaces during stamping and writing, resulting in excellent stamping and writing properties. Furthermore, in addition to exhibiting excellent writing properties with various writing instruments such as oil-based pens and pencils, it also allows for longer-lasting ink retention.

[0096] Inorganic particles (B) can be surface-treated with organic compounds or silicon compounds having an organic part within the molecule. In particular, when using a non-water-soluble medium, it is preferable to use inorganic particles (B) that have been surface-treated with an organic compound.

[0097] Inorganic particles (B) can also be used in combination with organic particles. Examples of organic particles include benzoguanidine particles, cross-linked polystyrene particles, and cross-linked acrylic particles.

[0098] The content of inorganic particles (B) in the total solid components of the coating layer forming composition is preferably 30% by mass or more and 70% by mass or less. If it is 30% by mass or more, it can suppress the deterioration of the stamping properties, and if it is 70% by mass or less, it can suppress the shedding of particles.

[0099] Furthermore, when both particles (B1) and (B2) are included, the total amount of these particles is within the aforementioned range. For example, the content of inorganic particles (B) is 35% by mass or more and 65% by mass or less.

[0100] In one embodiment, particles (B1) and (B2) may each contain multiple particles within a range that satisfies conditions such as a specified particle size. For example, particle (B1) may contain particles of different sizes within the range of (B1).

[0101] Inorganic particles (B) can be directly added to coating agents that have been modified with thermosetting resin composition (A), functional resin composition (C), and aqueous media. However, to eliminate coarse inorganic particles and obtain the desired dispersed particle size, a dispersion process is preferred after the inorganic particles are added. Furthermore, to obtain the desired dispersed particle size in a short time, it is more preferable to prepare a masterbatch of inorganic particles in advance. Examples of methods for dispersing inorganic particles include ball mills, sand mills, grinding mills, roller mills, agitators, colloid mills, ultrasonic homogenizers, homogenizing mixers, dissolvers, bead mills, wet jet mills, paint agitators, disc mixers, planetary mixers, and Henschel mixers. As for the average particle size of the dispersed particles, a 50% volume average particle size (Dv50) of 0.05 to 0.5 μm is preferred. When Dv50 is less than 0.05 μm, Ra and S become too small. Conversely, if Dv50 is greater than 0.5 μm, Ra becomes too large.

[0102] (Functional Resin Composition (C))

[0103] The functional resin composition (C) used in this invention complements the properties of the thermosetting resin composition (A), for example, it can improve printability, stampability, and mechanical strength. That is, in this invention, by simultaneously including both the thermosetting resin composition (A) and the functional resin composition (C), the effects of the thermosetting resin composition (A) can be achieved.

[0104] The functional resin composition (C) can be selected within a range that does not hinder the effect of the thermosetting resin composition (A), and examples include polyester resin, polyurethane resin, polystyrene resin, acrylic resin, etc. Alternatively, these resins can be used in combination, or copolymers of these resins can be used. Mixtures with other resins can also be used. Examples include urethane-acrylic copolymer resin, acrylic-styrene copolymer resin, etc. Other examples of the functional resin composition (C) include polymeric antistatic agents. From the perspective of improving the adhesion between the film and the coating layer, polyester resin is preferred. Furthermore, from the perspective of improving adhesion with UV inks and toners, acrylic-styrene copolymer resin is preferred. Additionally, to impart antistatic properties to the film, a polymeric antistatic agent is preferred as the functional resin composition (C). By imparting antistatic properties, multilayering during printing and the adhesion of foreign matter, dust, etc., can be prevented, therefore it is preferred.

[0105] (Polyester resin)

[0106] The polyester resin used to form the coating layer in this invention can be a linear polyester resin, more preferably a polyester resin composed of dicarboxylic acids and diols with branched structures. Regarding the dicarboxylic acids mentioned herein, in addition to terephthalic acid, isophthalic acid, or 2,6-naphthalenedicarboxylic acid as their main components, examples include 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.

[0107] Regarding the polyester resin, it is preferable that the total glycol composition contains a glycol component of the more preferred type described above at a proportion of 10 mol% or more, and more preferably 20 mol% or more. If it is less than 10 mol%, the crystallinity increases, and the adhesion of the coating layer may sometimes decrease. The upper limit of the glycol content in the total glycol composition is preferably 80 mol% or less, and more preferably 70 mol% or less by mass. If it is 80 mol% or more, the concentration of oligomers as byproducts increases, which may sometimes affect the transparency of the coating layer. As a glycol component other than the above-mentioned compound, ethylene glycol is most preferred. If in small amounts, diethylene glycol, propylene glycol, butanediol, hexanediol, or 1,4-cyclohexanediethanol may also be used.

[0108] The most preferred dicarboxylic acid component of the aforementioned polyester resin is terephthalic acid or isophthalic acid. In addition to the aforementioned dicarboxylic acid, to impart water dispersibility to the copolymer polyester resin, it is preferable to copolymerize 5-sulfonoisophthalic acid, etc., in the range of 1 to 10 mol%, such as sulfonoterephthalic acid, 5-sulfonoisophthalic acid, sodium isophthalate-5-sulfonate, etc. Polyester resins containing dicarboxylic acids with a naphthalene backbone can be used, but to suppress the reduction in adhesion to UV inks, the proportion of this dicarboxylic acid is preferably 5 mol% or less of the total carboxylic acid component, or it may be omitted.

[0109] For example, in the case of containing polyester resin, the content of functional resin (C) in the total solid components of the coating layer is 15-50% by mass, or 15-30% by mass. By including polyester resin in such an amount, the adhesion between the coating layer and the substrate layer can be improved.

[0110] (Acrylic-styrene copolymer resin)

[0111] The acrylic-styrene copolymer resin used in this invention is a polymer formed by alternating or randomly including acrylic monomers and styrene monomers in its structural units. Preferably, this acrylic-styrene copolymer resin contains 0.1% by mass or more and 15% by mass or less of the total solids content of the coating layer forming composition. More preferably, it contains 3% by mass or more and 15% by mass or less. If it is 0.1% by mass or more, the adhesion to UV inks and toners is improved, which is preferred. Furthermore, if it is 3% by mass or more, the adhesion to UV inks and toners is further improved, which is preferred. Furthermore, if it is 15% by mass or less, the adhesion, sealing properties, and antistatic properties of the coating are not deteriorated, which is therefore preferred.

[0112] (Polymer antistatic agent)

[0113] The polymeric antistatic agents used in this invention refer to polymeric compounds formed by introducing hydrophilic units as conductive units into the molecule. Based on the introduced conductive units (hydrophilic units), they are classified into nonionic polymeric antistatic agents (polyether ester amide system, ethylene oxide-epimerol system, polyether esters), anionic polymeric antistatic agents (polystyrene sulfonic acid system), and cationic polymeric antistatic agents (acrylate polymer system containing quaternary ammonium bases).

[0114] In this invention, any known substance can be used as long as the water dispersibility of the above-mentioned thermosetting resin composition (A), the above-mentioned inorganic particles (B), and the above-mentioned other functional resin composition (C) is maintained. From the perspective of maintaining the water dispersibility of the above-mentioned resin or particles, a polystyrene sulfonate-based polymeric antistatic agent is preferred.

[0115] The aforementioned polystyrene sulfonic acid-based polymeric antistatic agents are preferably formed as sulfonates, such as alkali metal salts of sulfonates. Examples of sulfonates include lithium, sodium, potassium, and calcium, which are quaternary ammonium ions or metal ions. From the perspective of maintaining antistatic properties even after the heating and drying process of the coating, the aforementioned metal ions are preferred.

[0116] The aforementioned antistatic agent preferably contains 4% by mass or more of the total solid components of the coating layer forming composition in 100% by mass. More preferably, it contains 5% by mass or more. If it is 4% by mass or more, the desired antistatic properties can be achieved. If it is 5% by mass or more, the desired antistatic properties can be achieved more stably.

[0117] Preferably, the antistatic agent comprises 20% by mass or less, for example, 15% by mass or less, of the total solid components of the coating layer forming composition (100% by mass). Within this range, the adhesion between the coating layer and the ink, and between the coating layer and the substrate layer, is not hindered by the performance of other resins.

[0118] (additive)

[0119] In addition to the thermosetting resin composition (A), inorganic particles (B), and functional resin composition (C) mentioned above, various additives such as leveling agents, inorganic particle dispersants, and antioxidants may also be added to the surface coating layer.

[0120] The coating agent comprising the modified thermosetting resin composition (A), inorganic particles (B), and functional resin composition (C) can be applied to the substrate film by the coating method described above, without particular limitation. For example, it can be any of the online coating method or the offline coating method.

[0121] The drying and curing temperature after coating is preferably 100°C or higher and less than 200°C. A temperature of 100°C or higher prevents insufficient drying and curing, and also prevents adhesion caused by insufficient curing of the thermosetting resin composition (A), therefore 100°C or higher is preferred. Furthermore, at temperatures below 200°C, the substrate film is less prone to shrinkage or deformation due to heat, allowing drying to be performed while maintaining planarity, therefore 200°C or lower is preferred. The drying and curing time is preferably 1 second or higher and less than 180 seconds. A time of 1 second or higher prevents insufficient drying, and also prevents adhesion caused by insufficient curing of the thermosetting resin composition (A), therefore 1 second or higher is preferred. From a productivity perspective, a time of less than 180 seconds helps control costs, therefore less than 180 seconds is preferred.

[0122] The thickness of the surface coating after drying and curing is preferably 2 to 20 μm. A thickness of 2 μm or more ensures sufficient volume for absorbing ink after stamping, therefore 2 μm or more is preferred. A thickness of 20 μm or less maintains the strength of the surface coating and prevents powder shedding, therefore 20 μm or less is preferred.

[0123] In one embodiment, the surface resistivity (logΩ / □) of the coated layer of the white laminated polyester film at 23°C and 65%RH is 14 or less, for example, 13.5 or less, or 13 or less.

[0124] By extending the film to this range, in addition to preventing multiple layers of film during printing, it can also prevent the toner from scattering during printing.

[0125] In addition, the surface resistivity (logΩ / □) can be 7 or higher, for example, 7.5 or higher, or 8 or higher.

[0126] Even if the surface resistivity is low, there is no particular problem. However, by keeping it within such a range, it is possible to effectively prevent the multilayering of the film and the dispersion of the toner, suppress the amount of antistatic agent, and thus reduce production costs.

[0127] The surface resistivity of the coated layer of a white laminated polyester film can be determined using known methods.

[0128] The white laminated polyester film of the present invention can be used for applications such as insurance certificates, qualification certificates, driver's licenses, student IDs, registration certificates, business cards and other cards, business labels, delivery slips, printer paper, and labels.

[0129] In addition, there are no particular limitations on the types of inks that can be used on white laminated polyester films; for example, UV-curable inks, oil-based inks, water-based inks, and pencil inks can be used.

[0130] Example

[0131] 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.

[0132] (1) Adhesion to the coating

[0133] On the coated layer of the laminated polyester film, use Michelin cellophane tape (CT405AP-24), cut into pieces 24mm wide and 50mm long, and use a hand-held rubber roller to completely adhere it to the ink layer surface without introducing air. Then, peel off the cellophane tape vertically and observe the remaining area of ​​the coating layer in a 24mm × 50mm area, judging according to the following criteria.

[0134] ◎: The residual area of ​​the coating layer is more than 99% of the total area.

[0135] ○: The residual area of ​​the coating layer is more than 90% and less than 99% of the total area.

[0136] △: The residual area of ​​the coating layer is more than 70% but less than 90% of the total area.

[0137] ×: The residual area of ​​the coating layer is less than 70% of the total area.

[0138] (2) Adhesion to UV ink

[0139] On the coated layer of the laminated polyester film, UV ink [manufactured by T&K TOKA Co., Ltd., trade name "BEST CUREUV161 Blue S"] was used for printing using a printing press [manufactured by Meiji Seisakusho Co., Ltd., trade name "RI Tester"]. Then, the film coated with the ink layer was irradiated with a high-pressure mercury lamp at 40 mJ / cm². 2The UV light is used to cure the UV-curable ink. Next, using Michelin cellophane tape (CT405AP-24), cut into pieces 24mm wide and 50mm long, it is rolled onto the ink layer surface by hand with a rubber roller to ensure no air is trapped. Afterward, the cellophane tape is peeled off vertically, and the remaining area of ​​the printed layer is observed in the 24mm × 50mm area, and judged according to the following criteria.

[0140] ◎: The residual area of ​​the printed layer is over 99% of the total area.

[0141] ○: The residual area of ​​the printed layer is more than 90% but less than 99% of the total area.

[0142] △: The residual area of ​​the printed layer is more than 70% but less than 90% of the total area.

[0143] ×: The residual area of ​​the printed layer is less than 70% of the total area.

[0144] (3) Stamping properties on the coating layer

[0145] Stamp the white laminated polyester film coating with Shachihata Xstanper Name 9 (pigment ink: XLR-9N) and let it stand for 1 minute. Then, gently rub the stamped area with a wiping paper and observe the friction of the text, judging according to the following criteria.

[0146] ○: No blurring occurred at all

[0147] △: Produces blur, but text can still be recognized.

[0148] ×: Difficult to recognize text

[0149] (4) The writing properties of the coating layer

[0150] Write on the coated layer of white laminated polyester film using a ballpoint pen SXN-150-07JETSTREAM 24 black (refill: SXR-7), and let it sit for 1 minute. Then, gently rub the writing area with erasing paper and observe the friction of the text, judging according to the following criteria.

[0151] ○: No blurring occurred at all

[0152] △: Produces blur, but text can still be recognized.

[0153] ×: Difficult to recognize text

[0154] (5) Printability

[0155] Using an electrophotographic copier (Fuji Xerox C3376), toner was transferred onto the surface coating layer in 10 consecutive prints and then fixed. The degree of toner dispersion at this point was evaluated according to the following criteria.

[0156] 〇: No toner was observed to scatter from the printing area.

[0157] △: Toner dispersion was observed in an area of ​​0.5 mm to 5 mm from the printed area.

[0158] ×: Toner dispersion was observed at a distance of more than 5 mm from the printed area.

[0159] (6) Fixing properties of toners

[0160] Using an electrophotographic copier (Fuji Xerox C3376), toner is transferred onto the surface coating of the film and fixed. After the adhesive layer of the tape (Mickey & Co. Cellotpe (registered trademark), 25mm wide) is firmly adhered to the toner fixing surface, it is quickly peeled off at a 90° angle relative to the film surface. The toner residue on the film is then visually assessed according to the following criteria.

[0161] ○: The residual toner on the surface coating layer of the membrane is more than 90% of the area.

[0162] △: The residual toner on the surface coating layer of the membrane is more than 70% but less than 90% of the area.

[0163] ×: Toner residue on the surface coating of the membrane is less than 70% of the area.

[0164] (7) Dusting property

[0165] Regarding the evaluation of dust shedding properties, in a dust shedding vibration friction tester (manufactured by Yamaguchi Scientific Industries Co., Ltd.), black backing paper (GA BOARD-FS, Y-mesh, manufactured by Takeo Co., Ltd.) was used at the contact area between the load head and the membrane, and the load on the head was set to 200 gf / 25 mm. 2 (5mm×5mm) [0.0785MPa], the state of the black backing paper after the film is rubbed against the load head three times through visual evaluation of the limit sample in 5 stages, and 4 or above is qualified.

[0166] (8) Surface resistivity of the coating layer

[0167] After placing the white laminated polyester film at 23°C and 65% RH for 24 hours, the surface resistivity (logΩ / □) of the coating layer was measured using a surface resistivity measuring device (Mitsubishi Yuka Co., Ltd., Hiresta-IP) under the same atmosphere with an applied voltage of 500V and a measurement time of 10 seconds.

[0168] (9) The specular gloss of the coated layer of the white laminated polyester film was determined according to method 3 (60-degree specular gloss) as described in JIS-Z8741.

[0169] (10) Surface roughness (Ra), maximum protrusion height (Rz)

[0170] Ra and Rz were measured using the formulas in ISO 4287:1997, with the arithmetic mean roughness and maximum protrusion height determined respectively. A VK-X100 laser microscope (manufactured by Keyence) was used for the measurements. A 250μm × 250μm square was designated as one point for the arithmetic mean roughness or maximum height, and four points were randomly measured. The average value was taken as the surface roughness or maximum protrusion height value (unit: μm).

[0171] [Thermosetting resin composition (A)]

[0172] (Polymerization of urethane resin A-1 with a polycarbonate structure)

[0173] To a four-necked flask equipped with a stirrer, a serpentine condenser, a nitrogen inlet tube, a silica gel drying tube, and a thermometer, 25 parts by mass of 4,4-dicyclohexylmethane diisocyanate, 5 parts by mass of dimethylolpropionic acid, 52 parts by mass of polyhexamethylene carbonate diol with a number average molecular weight of 2600, 6 parts by mass of neopentyl glycol, and 84.00 parts by mass 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 reached the specified amine equivalent. Next, 18 parts by mass of a polyisocyanate compound (Asahi Kasei Chemicals, DURANATE TPA, 3-functional) with an isocyanurate structure based on hexamethylene diisocyanate was added, and the mixture was stirred at 75°C for 1 hour under a nitrogen atmosphere to confirm that the reaction solution reached the specified amine equivalent. Afterward, the temperature of the reaction solution was lowered to 50°C, and 8 parts by mass of methyl ethyl ketone oxime were added dropwise. After cooling the reaction solution to 40°C, 5.17 parts by mass of triethylamine were added to obtain a polyurethane prepolymer solution. Next, 450g of water was added to the reaction vessel equipped with a high-speed homogenizer, the temperature was adjusted to 25°C, and the mixture was stirred at a speed of 2000 min. -1 The mixture was stirred while adding a polyurethane prepolymer solution for water dispersion. Then, acetone and a portion of the water were removed under reduced pressure, thereby preparing a water-dispersible urethane resin solution (A-1) with a solid content of 35% by mass.

[0174] (Polymerization of urethane resin A-2 with a polycarbonate structure)

[0175] To a four-necked flask equipped with a stirrer, a serpentine condenser, a nitrogen inlet tube, a silica gel drying tube, and a thermometer, 22 parts by mass of 4,4-dicyclohexylmethane diisocyanate, 20 parts by mass of polyethylene glycol monomethyl ether with a number average molecular weight of 700, 53 parts by mass of polyhexamethylene carbonate glycol with a number average molecular weight of 2100, 5 parts by mass of neopentyl glycol, and 84.00 parts by mass 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 reached the specified amine equivalent. Next, 16 parts by mass of a polyisocyanate compound (Asahi Kasei Chemicals, DURANATE TPA, 3-functional) with an isocyanurate structure based on hexamethylene diisocyanate was added, and the mixture was stirred at 75°C for 1 hour under a nitrogen atmosphere to confirm that the reaction solution reached the specified amine equivalent. Afterward, the temperature of the reaction solution was lowered to 50°C, and 7 parts by mass of methyl ethyl ketone oxime were added dropwise. After cooling the reaction solution to 40°C, a polyurethane prepolymer solution was obtained. Next, 450g of water was added to the reaction vessel equipped with a high-speed homogenizer, the temperature was adjusted to 25°C, and the mixture was stirred at a speed of 2000 min. -1 The mixture was stirred while adding a polyurethane prepolymer solution for water dispersion. Then, acetone and a portion of the water were removed under reduced pressure, thereby preparing a water-dispersible urethane resin solution (A-2) with a solid content of 35% by mass.

[0176] (Polymerization of urethane resin A-3 without polycarbonate structure)

[0177] 75 parts by weight of a polyester polyol with a molecular weight of 5000, consisting of terephthalic acid, isophthalic acid, ethylene glycol, and neopentyl glycol, 30 parts by weight of hydrogenated isophthalamide diisocyanate, 7 parts by weight of ethylene glycol, 6 parts by weight of dimethylolpropionic acid, and 84.00 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 reached the specified amine equivalent. After cooling the reaction solution to 40°C, 5.17 parts by weight of triethylamine were added to obtain a polyurethane prepolymer solution. Next, 450 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 speed of 2000 min... -1 The mixture was stirred while adding a polyurethane prepolymer solution for water dispersion. Then, acetone and a portion of the water were removed under reduced pressure, thereby preparing a water-dispersible urethane resin solution (A-3) with a solid content of 34% by mass.

[0178] (Polymerization of urethane resin A-4 with a polycarbonate structure)

[0179] A four-necked flask equipped with a stirrer, a serpentine condenser, a nitrogen inlet tube, a silica gel drying tube, and a thermometer was added to a mixture of 400 parts by mass of a polycarbonate polyol with a number average molecular weight of 2000 (composed of 1,6-hexanediol and diethyl carbonate), 10.4 parts by mass of neopentyl glycol, 58.4 parts by mass of isophorone diisocyanate, 74.3 parts by mass of dimethylolbutyric acid, and 320 parts by mass of acetone as a solvent. The mixture was stirred at 75°C for 3 hours under a nitrogen atmosphere to confirm that the reaction solution reached the specified amine equivalent. The reaction solution was then cooled to 40°C, and isophorone diamine was added to obtain a polyurethane prepolymer solution. Next, 1200 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 The mixture was stirred while adding a polyurethane prepolymer solution for water dispersion. Then, acetone and a portion of the water were removed under reduced pressure, thereby preparing a water-dispersible urethane resin solution (A-4) with a solid content of 34% by mass.

[0180] • Melamine resin A-5 (AMIDIR (registered trademark) M-3, manufactured by DIC Corporation, 80% by weight solids), • Carbodiimide resin A-6 (CARBODILITE (registered trademark) V-10, manufactured by Nisshin Spinning Co., Ltd., 40% by weight solids), • Oxazoline-containing resin A-7 (EPOCROS (registered trademark) WS-300, manufactured by Nippon Shokubai Co., Ltd., 10% by weight solids)

[0181] [Inorganic Particles B1]: · Calcium Carbonate B-1 (Baiyanhua (registered trademark) Pz, manufactured by Baishi Calcium Company, 100% solids by mass, average particle size 0.2μm) · Calcium Carbonate B-2 (Brilliant (registered trademark)-15, manufactured by Baishi Calcium Company, average particle size 0.15μm, 100% solids by mass) · Calcium Carbonate B-3 (Tunex (registered trademark) E, manufactured by Baishi Calcium Company, average particle size 0.5μm, 100% solids by mass) [Inorganic Particles B2]: Silica B-4 (SYLYSIA (registered trademark) 440, manufactured by FUJISILYSIA CHEMICAL, average particle size 6.2μm, 100% solids by mass) · Silica B-5 (SYLYSIA (registered trademark) 450, manufactured by FUJI SILYSIA CHEMICAL, average particle size 8.0μm, 100% solids by mass)

[0182] [Functional Resin Composition (C)]: • Styrene-acrylic resin C-1 (Sabinol (registered trademark) EK215, manufactured by SAIDEN CHEMICAL INDUSTRY, solid content 25% by mass) • Styrene-acrylic resin C-2 (Sabinol (registered trademark) EK119, manufactured by SAIDEN CHEMICAL INDUSTRY, solid content 36% by mass) • Polyester resin C-3 (VYLONAL (registered trademark) MD1200, manufactured by Toyobo Co., Ltd., solid content 34% by mass) • Polymer antistatic agent C-4 (EL polymer WS-52R, manufactured by Shin-Nakamura Chemical Industry Co., Ltd., solid content 10% by mass) • Polymer antistatic agent C-5 (Fujistat YE910, manufactured by Fuji Chemical Industries Co., Ltd., solid content 15% by mass) • Polymer antistatic agent C-6 (Fujistat YE125, manufactured by Fuji Chemical Industries Co., Ltd., solid content 15% by mass) High molecular weight antistatic agent C-7 (Fujistat YE915, manufactured by Fuji Chemical Industries, 25% solids by mass) (Fujistat YE915, manufactured by Fuji Chemical Industries, 15% solids by mass)

[0183] (Substrate Film) Crisper (Registered Trademark) K1211: White polyester film with voids, manufactured by Toyobo Co., Ltd., single-sided corona treatment / single-sided untreated, apparent density 1.1 g / cm³ 3 Ra = 0.1μm, Rz = 3μm, S = 2μm (Ra, Rz, S are data for the corona discharge surface) · Crisper (registered trademark) K2323: Manufactured by Toyobo Co., Ltd., white polyester film containing voids, double-sided easy-to-stick treatment, apparent density 1.1g / cm³ 3 Ra = 0.3 μm, Rz = 7 μm, S = 2 μm (Ra, Rz, and S are essentially the same on both surfaces)

[0184] (Example 1)

[0185] (Adjustment of coating layer forming composition 1)

[0186] The following composition is adjusted to form a coating layer to form composition 1.

[0187] (Coating layer forming composition 1)

[0188]

[0189] (Coating and drying on the substrate film)

[0190] Using a 50 μm thick polyester synthetic paper Crisper K1211 as the substrate film, a coating layer was applied to the corona-treated surface of K1211 to form composition 1, with a dry coating layer thickness of 10 μm. The mixture was then dried at 180°C for 60 seconds to obtain the white laminated polyester film described in Example 1.

[0191] (Examples 2-25, Comparative Examples 1-6)

[0192] Examples 2-25 and Comparative Examples 1-6 were coated, dried, and cured in the same manner as in Example 1, except that the substrate film, coating layer composition, coating surface, and thickness after drying were changed as shown in Tables 1, 2, and 3, to obtain white laminated polyester films.

[0193] In Tables 1, 2, and 3, the composition ratios of the thermosetting resin composition A, inorganic particles B, and functional resin composition C in the coating layer forming composition are expressed as the mass parts of each solid component when the overall solid content ratio is set to 100. The actual coating layer forming composition was mixed with water at a liquid-to-solid content ratio of 25%.

[0194] The table below shows the mixing amounts and various physical properties of each component.

[0195] [Table 1]

[0196]

[0197] [Table 2]

[0198]

[0199] [Table 3]

[0200]

[0201] Tables 4, 5, and 6 show the evaluation results of each embodiment and comparative example.

[0202] [Table 4]

[0203]

[0204] [Table 5]

[0205]

[0206] [Table 6]

[0207]

[0208] In Examples 1 to 25, the coating and ink adhere well, and it also has stamping and writing properties.

[0209] On the other hand, in Comparative Examples 1, 2, and 3, the urethane resin lacked a polycarbonate structure, resulting in reduced coating strength and peeling during coating adhesion and ink adhesion evaluations. In Comparative Example 4, the proportion of urethane resin was low, leading to reduced coating strength and peeling during coating adhesion and ink adhesion evaluations. In Comparative Example 5, the proportion of urethane resin was low, resulting in reduced adhesion to the ink layer and peeling. Furthermore, insufficient ink absorption led to bleed-through of unreadable characters during stamping and writing performance evaluations. In Comparative Example 6, the urethane resin had a polycarbonate structure, but lacked a branched structure, resulting in reduced coating strength and peeling during coating adhesion and ink adhesion evaluations.

[0210] Industrial availability

[0211] According to the present invention, a laminated white polyester film can be provided, which has the properties of adhesion of the coating layer to the substrate layer, adhesion to UV ink, stamping and writing properties.

Claims

1. A white laminated polyester film, wherein at least one side of a white polyester resin layer has a coating layer formed of a coating layer forming composition comprising a thermosetting resin composition (A), inorganic particles (B), and a functional resin composition (C), wherein, The thermosetting resin composition (A) contains at least a urethane resin having a polycarbonate structure and a branched structure, and In the total solid components of the coating layer forming composition, the content of the urethane resin having a polycarbonate structure and a branched structure is 4% by mass or more and 12% by mass or less, accounting for 100% by mass of the total solid components. The inorganic particles (B) include two or more particles (B1) with an average particle size of 0.1 μm or more and less than 1.0 μm and particles (B2) with an average particle size of 1.0 μm or more and less than 10.0 μm. The mixing amounts of B1 and B2 have the following relationship: B1 / B2 = more than 1.0 and less than 4.

0.

2. The white laminated polyester film according to claim 1, wherein, The content of inorganic particles (B) in the total solid components of the coating layer is 30% by mass or more and 70% by mass or less.

3. The white laminated polyester film according to claim 1, wherein, The functional resin composition (C) comprises a compound selected from at least one of polyester resin, acrylic-styrene copolymer resin, and polymeric antistatic agent.

4. The white laminated polyester film according to claim 3, wherein, The polymeric antistatic agent is a resin containing at least a sulfonate.

5. The white laminated polyester film according to claim 3, wherein, The polymeric antistatic agent is a resin containing sulfonic acid alkali metal salts.

6. The white laminated polyester film according to any one of claims 1 to 5, wherein, The coated layer of the white laminated polyester film has a surface resistivity of less than 13 logΩ / □ at 23°C and 65%RH.

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