JP2003071995A - Laminated polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated polyester film which is free from application nonuniformity and excellent in adhesion, scratch resistance, blocking resistance, and transparency by uniformly dispersing each component in a lamination film on a polyester film. SOLUTION: In the laminated polyester film, the lamination film containing an acrylic resin and another resin is formed at least on one side of the polyester film. Dispersion indices in both direction of the lamination film are 2-20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated polyester film, and more particularly to a laminated polyester film having a structure in which each component in a laminated film on a polyester film is uniformly dispersed. The present invention relates to a laminated polyester film having excellent properties, scratch resistance, blocking resistance, and transparency.

[0002]

2. Description of the Related Art Conventionally, it has been proposed to provide a laminated film in which an acrylic copolymer and a resin other than an acrylic resin are mixed for the purpose of imparting easy adhesion or an antistatic function to a polyester film (Japanese Patent Laid-Open No. 8- 300590, etc.). Further, a laminated film having a coating film formed of a mixture of an acrylic resin and polystyrene sulfonic acid and / or a salt thereof has been proposed (JP-A-61-2424).
No. 0, JP-A No. 1-9242, etc.).

[0003]

However, in the conventional laminated polyester film as described above, due to the difference in surface free energy between the acrylic resin and the resin other than the acrylic resin, mutual exclusion in the process of forming the laminated film, That is, in the coating liquid state, two or more kinds of substances that are dissolved in the solvent or dispersed in the solvent due to mutual repulsion due to surface charge are applied,
When the solvent evaporates through drying, a partial aggregate of substances of the same kind is formed, mutual separation occurs at the time of forming the coating film, and a state in which it is difficult to form a structure that is substantially finely dispersed in each other occurs. As a result, the intended function may be insufficiently expressed in the laminated film, which is essentially required for uniform mixing.

This tendency is likely to occur in a temperature range where the compositions are easy to move, for example, at a temperature above the glass transition point of each composition, and the higher the temperature, the more prominent the tendency is. In practice, it is more remarkably exhibited in a method (in-line coating method) in which the polyester film is applied in the film forming step, and dried, stretched and heat-treated. For example, in the case of a mixture of hydrophilic polyester and acryl, the structure in which polyester and acryl are phase-separated in the laminated film, and when polystyrene sulfonic acid and / or its salt is mixed in acryl, acryl is obtained by phase separation. Part and polystyrene sulfonic acid and /
Or, it was proved by our experiment that the salt individually forms a sub-assembly and has a macro-dispersed structure. When such a configuration is adopted, the expected original function of the laminated film is often not sufficiently exhibited by mixing. For example, in the case of a mixed system with a polystyrene sulfonic acid type, when the resin that exhibits extremely fragile properties in a dry state exists as an aggregate in the laminated film, the laminated film itself becomes brittle, and scratch resistance is poor or hydrophilic. Strong polystyrene sulfonic acid and /
Alternatively, the salt thereof is unevenly distributed in the laminated film, which causes problems such as deterioration in water resistance and blocking resistance under high humidity. Further, if the uneven distribution becomes extreme, the laminated film is cracked in the above in-line coating, which causes a problem that the commercial value is remarkably reduced.

The object of the present invention is to provide a laminated polyester film which does not have the above-mentioned drawbacks in which the mutual composition is uniformly dispersed in the laminated film containing an acrylic resin and a resin other than the acrylic resin. It is what

[0006]

The present invention provides a laminated polyester film in which a laminated film containing an acrylic resin and a resin other than the acrylic resin is provided on at least one surface of the polyester film, and The essence is a laminated polyester film having a dispersion index of 2 to 20.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester of the polyester film in the present invention is a composition obtained by polycondensing a dicarboxylic acid and a diol, and preferable polyesters include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate and polyethylene. Examples thereof include -2,6-naphthalate. Among them, polyester containing 90 mol% or more of ethylene terephthalate units is particularly preferable. Of course, it may be a copolymer of dicarboxylic acid and diol other than these. For example, isophthalic acid, 5-sodium sulfoisophthalic acid, adipic acid, sebacic acid and ester-forming derivatives thereof, diethylene glycol, propylene glycol, neopentyl glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol,
Polyethylene glycol, polypropylene glycol,
Examples thereof include diols such as polytetraethylene glycol. The polyester film using this polyester may be either unstretched, uniaxially stretched or biaxially stretched, but biaxially stretched is particularly preferable in consideration of mechanical strength, dimensional stability and the like. The biaxial stretching can be performed by any method such as a sequential biaxial stretching method, a simultaneous biaxial stretching method, or a method in which the biaxial stretching is followed by stretching in the longitudinal and / or transverse directions again.

Various additives can be used in the polyester film as long as the effects of the present invention are not impaired. For example, antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, organic and inorganic fine particles, lubricants, pigments, dyes,
Fillers, antistatic agents, nucleating agents, cross-linking agents and the like can be mentioned. Further, it may be a composite film composed of two or more layers of an inner layer and a surface layer. As a specific example, the inner layer portion does not substantially contain particles, the surface layer portion is a composite film having a layer containing particles, particles or polyester incompatible resin is dispersed in the inner layer portion and finely drawn by stretching. Examples include, but are not limited to, a fine bubble-containing polyester film in which bubbles are generated, a white film in which titanium oxide or a fluorescent whitening agent is added to polyester, and the like.

As the acrylic resin of the present invention, for example, an acrylic resin emulsion dispersed in water can be used, and the dispersion diameter thereof is preferably 20 to 200 nm, more preferably 30 to 100 nm, compared with other resins. Desirable for dispersion. In order to obtain a dispersion diameter of less than 20 nm, it is necessary to increase the amount of the emulsifier used due to its specific surface area when an acrylic emulsion is prepared by emulsion polymerization or the like, which may cause a problem in adhesiveness. 20
When it exceeds 0 nm, fine dispersion may be difficult. The glass transition temperature of the acrylic resin is 0 to
The range of 80 ° C. is preferable, and more preferably 10 to 70.
If the glass transition temperature is too low, it may be disadvantageous in blocking resistance. If it is too high, instability of the resin when dispersed in water may be a problem.

The monomer component constituting the acrylic resin is not particularly limited, but examples thereof include alkyl acrylate and alkyl methacrylate (wherein the alkyl group is methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group). Group, isobutyl group, t-butyl group,
2-ethylhexyl group, lauryl group, stearyl group, cyclohexyl group, phenyl group, benzyl group, phenylethyl group, etc.), 2-hydroxyethyl acrylate, 2
-Hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, hydroxy group-containing monomers such as 2-hydroxypropyl methacrylate, acrylamide, methacrylamide, N-methylacrylamide, N
Amide group-containing monomers such as -methylmethacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, N, N-dimethylolacrylamide, N-methoxymethylacrylamide, N-methoxymethylmethacrylamide, and N-phenylacrylamide,
N, N-diethylaminoethyl acrylate, N, N-
Amino group-containing monomers such as diethylaminoethyl methacrylate, epoxy group-containing monomers such as glycidyl acrylate and glycidyl methacrylate, carboxyl groups such as acrylic acid, methacrylic acid and their salts (lithium salt, sodium salt, potassium salt, etc.) or salts thereof. It is possible to use the contained monomer,
These are copolymerized using one kind or two or more kinds.
Furthermore, these can be used in combination with other types of monomers.

Examples of other types of monomers include, for example,
Epoxy group-containing monomers such as allyl glycidyl ether, monomers containing carboxyl groups or salts thereof such as crotonic acid, itaconic acid, maleic acid, fumaric acid and salts thereof (lithium salt, sodium salt, potassium salt, ammonium salt, etc.) , Monomers containing acid anhydrides such as maleic anhydride, itaconic anhydride, vinyl isocyanate, allyl isocyanate, styrene, vinyl methyl ether, vinyl ethyl ether, vinyl trisalkoxysilane, alkyl maleic acid monoester, alkyl fumaric acid monoester , Acrylonitrile, methacrylonitrile, alkyl itaconic acid monoester, vinylidene chloride, vinyl chloride, vinyl acetate and the like can be used. Further, a modified acrylic copolymer, for example, a block copolymer modified with polyester, urethane, epoxy or the like, a graft copolymer or the like can also be used.

The preferred acrylic resin used in the present invention is a copolymer selected from methyl methacrylate, ethyl acrylate, n-butyl acrylate, 2-hydroxyethyl acrylate, acrylamide, N-methylol acrylamide and acrylic acid.

The gist of the present invention is to uniformly finely disperse the other composition components in the acrylic resin, but in order to achieve this, it is necessary to select a specific acrylic resin.

The specific acrylic resin is that in the above-mentioned acrylic resin emulsion, the monomer component constituting the acrylic resin has 2 or more, preferably 3 or more, more preferably 5 or more alkylene oxide units, and / Alternatively, it is important to have an anionic group.

The alkylene oxide has 2 to 8 carbon atoms.
Those of ethylene oxide, propylene oxide, and a combination of ethylene oxide and propylene oxide are preferred, and ethylene oxide is most preferred. To contain such an alkylene oxide unit in the acrylic copolymer, it can be obtained by copolymerizing a monomer having one or more vinyl bonds and having an alkylene oxide unit. The compound having one or more vinyl bonds and an alkylene oxide unit has 2 to 2 alkylene oxide repeating units.
0 polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, polyethylene glycol / polypropylene glycol monomethacrylate, polyethylene glycol / polytetramethylene glycol monomethacrylate, polypropylene glycol / polytetramethylene glycol, polyethylene glycol monoacrylate, polypropylene glycol / monoacrylate, etc. There is no particular limitation as long as the above concept is satisfied.

In addition to containing the above alkylene oxide unit, it is important to further contain an anionic group in order to exert the effect of the present invention. Examples of the anionic group-containing monomer include compounds containing a sulfonic acid group and / or a sulfonate group, and are not particularly limited, but examples thereof include 2-sulfoethyl methacrylate, 2
-Sulfoethyl acrylate, styrene sulfonic acid, vinyl sulfonic acid and counter ion of its sulfonic acid group is ammonium, monovalent alkali metal, alkaline earth metal,
Examples include lithium, sodium, potassium and the like.

It was found that the presence of both the alkylene oxide unit and the anionic group on the surface of the acrylic resin emulsion markedly improves the effect of the present invention. It is important that both the monomer having an alkylene oxide unit and the monomer having an anionic group undergo a copolymerization reaction with an acrylic resin, and the effect of the present invention is obtained when a monomer added by adsorption of a usual surfactant is used. Is insufficient. The ratio of the monomer having an alkylene oxide unit to the monomer having an anionic group is not particularly limited, but the weight ratio of the alkylene oxide-containing monomer / anionic group-containing monomer is preferably 95/5 to
A range of 20/80, preferably 90/10 to 40/60 is effective.

The copolymerization ratio with respect to the acrylic resin, which is the total of the monomers having alkylene oxide units and the monomers having anionic groups, is 0.2 to 10 mol%, preferably 0.5 to 7 mol%, more preferably 1 It is desirable that the content is -5 mol% in order to exert the effects of the present invention.
If it is less than 0.2 mol%, uniform dispersibility is insufficient, and 10 mol%
If it exceeds the range, the water resistance and the anti-blocking property may be deteriorated. By using the above specific acrylic resin emulsion, resins other than the acrylic resin can be uniformly dispersed in the acrylic resin.

The method for polymerizing the acrylic resin emulsion in the present invention is not particularly limited, but emulsion polymerization, suspension polymerization and the like are usually preferably used.

The resin other than the acrylic resin is not particularly limited as long as it has a hydrophilic group, and examples thereof include polyester resin, polyurethane resin, polystyrene sulfonic acid and / or its salt. it can. The hydrophilic group is not particularly limited as long as it is a functional group having a hydrophilic property and a water dispersible function, and examples thereof include a carboxylic acid group and a carboxylic acid group, a sulfonic acid group and a sulfonic acid group, and an ester group. , Amide group, amino group, hydroxyl group, glycidyl group, acetyl group and the like. Of these, a sulfonate group and a sulfonate group are preferred. The amount of the hydrophilic group is preferably 50 mol% or more of the monomer having a hydrophilic group used for copolymerization or polycondensation. These resins are mixed and applied with an acrylic resin emulsion, but since the acrylic emulsion is dispersed in water, it needs to be dissolved or dispersed in water. It is also effective that the resin other than the acrylic resin has a hydrophilic group so as to be dissolved or dispersed in water. Representative compositions of each are shown below, but of course the invention is not limited to these.

The polyester resin has an ester bond in its main chain or side chain and is obtained by polycondensing a dicarboxylic acid and a diol.

As the carboxylic acid component constituting the polyester resin, an aromatic, aliphatic or alicyclic dicarboxylic acid or a trivalent or higher polycarboxylic acid can be used.

As the aromatic dicarboxylic acid, terephthalic acid, isophthalic acid, orthophthalic acid, phthalic acid, 2,5
-Dimethylterephthalic acid, 1,4-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,2-bisphenoxyethane-p, p '
-Dicarboxylic acids, phenylindanedicarboxylic acids and their ester-forming derivatives can be used. The aliphatic and alicyclic dicarboxylic acids include succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, dimer acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,4-Cyclohexanedicarboxylic acid and the like, and ester-forming derivatives thereof can be used.

As the glycol component of the polyester resin, ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-propanediol, 1,3
-Butanediol, 1,4-butanediol, 1,5-
Pentanediol, 1,6-hexanediol, 1,7
-Heptanediol, 1,8-octanediol, 1,
9-nonanediol, 1,10-decanediol, 2,
4-dimethyl-2-ethylhexane-1,3-diol, neopentyl glycol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 3 -Methyl-1,5
-Pentanediol, 2,2,4-trimethyl-1,6
-Hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-
Cyclohexanedimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 4,4'-thiodiphenol, bisphenol A, 4,4'-methylenediphenol, 4,4 '-(2 -Norbornylidene)
Diphenol, 4,4'-dihydroxybiphenol,
o-, m-, and p-dihydroxybenzene, 4,
4'-isopropylidenephenol, 4,4'-isopropylidenebindiol, cyclopentane-1,2-diol, cyclohexane-1,2-diol, cyclohexane-1,4-diol and the like can be used.

Further, in the present invention, the polyester resin must be used as an aqueous liquid dissolved or dispersed in water. In order to facilitate water-solubilization or water-dispersion of the polyester resin, it is preferable to copolymerize a compound containing a sulfonate group and a compound containing a hydrophilic group containing a carboxylate group.

Examples of the compound containing a sulfonate group include sulfoterephthalic acid, 5-sulfoisophthalic acid,
4-sulfoisophthalic acid, 4-sulfonaphthalene-2,
7-dicarboxylic acid, sulfo-p-xylylene glycol, 2-sulfo-1,4-bis (hydroxyethoxy)
Alkali metal salts such as benzene, alkaline earth metal salts,
Ammonium salts can be used, but are not limited thereto.

Examples of the compound containing a carboxylate group include trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, 4-methylcyclohexene-1,2,3-tricarboxylic acid, trimesic acid, and 1 ，
2,3,4-butanetetracarboxylic acid, 1,2,3,4
-Pentane tetracarboxylic acid, 3,3 ', 4,4'-benzophenone tetracarboxylic acid, cyclopentane tetracarboxylic acid, 2,3,6,7-naphthalene tetracarboxylic acid, 1,2,5,6-naphthalene tetra carboxylic acid,
Ethylene glycol bis trimellitate, 2,2 ',
3,3'-diphenyltetracarboxylic acid, thiophene-
Alkali metal salts such as 2,3,4,5-tetracarboxylic acid and ethylene tetracarboxylic acid, alkaline earth metal salts,
Examples thereof include, but are not limited to, ammonium salts and the like.

In the present invention, a modified polyester copolymer such as a block copolymer or a graft copolymer modified with acryl, urethane or epoxy can be used as the polyester resin.

The above-mentioned polyester resin can be produced by a direct esterification reaction of a dicarboxylic acid component and a glycol component, or a polycondensation reaction product of a transesterification reaction. it can. At this time, as the reaction catalyst, for example, an alkali metal, an alkaline earth metal, manganese, cobalt, zinc, antimony, germanium, a titanium compound or the like can be used.

The intrinsic viscosity of the polyester resin is not particularly limited, but it is preferably 0.3 dl / g or more, more preferably 0.35 dl / g, from the viewpoint of adhesiveness.
That is all. The glass transition temperature of polyester resin is 0
Is preferably 130 ° C, more preferably 10 ° C.
~ 85 ° C. When the glass transition temperature is lower than 0 ° C, for example, heat-resistant adhesiveness is poor, or a blocking phenomenon occurs in which laminated films are fixed to each other. On the contrary, when the glass transition temperature is higher than 130 ° C, stability and water dispersibility of the resin are poor. There are cases.

As the polyurethane resin, a water-soluble or water-dispersible polyurethane resin having an anionic group is exemplified, and a reaction product consisting of a polyol compound and a polyisocyanate compound is a basic structure as a main constituent component. It is a thing.

As the anionic group in the polyurethane resin, a carboxylic acid group, a sulfonic acid group, or a sulfuric acid half ester group, and their ammonium salts, lithium salts, sodium salts, potassium salts and the like can be used. Particularly preferred is sulfonic acid and / or sulfonate group.

The amount of anionic groups in the polyurethane resin is preferably 0.05% by weight to 15% by weight. 0.05
If it is less than 10% by weight, the water dispersibility of the polyurethane resin tends to be poor, and if it exceeds 15% by weight, the water resistance of the resin tends to be poor, or a blocking phenomenon in which laminated films adhere to each other tends to occur.

Examples of the polyol compound include polyethylene glycol, polypropylene glycol, polyethylene propylene glycol, polytetramethylene glycol, hexamethylene glycol, hexamethylene glycol, tetramethylene glycol, 1,5-pentanediol, diethylene glycol and triethylene glycol. , Polycaprolactone, polyhexamethylene adipate, polytetramethylene adipate, trimethylolpropane, trimethylolethane, glycerin,
Acrylic polyol and the like can be used.

As the polyisocyanate compound, for example, tolylene diisocyanate, hexamethylene diisocyanate, phenylene diisocyanate, diphenylmethane diisocyanate, an addition product of tolylene diisocyanate and trimethylol propane, an addition product of hexamethylene diisocyanate and trimethylol ethane, etc. Can be used.

Here, the main constituent components of the polyurethane resin may contain a chain extender or a crosslinking agent in addition to the above-mentioned polyol compound and polyisocyanate compound. As the chain extender or crosslinking agent, ethylene glycol, propylene glycol, butanediol, diethylene glycol, ethylenediamine, diethylenetriamine, etc. can be used.

The polyurethane resin having an anionic group can be obtained, for example, by using a compound having an anionic group in a polyol, polyisocyanate, chain extender or the like,
It can be produced by a method of reacting the unreacted isocyanate group of the generated urethane resin with a compound having an anionic group, or a method of reacting a group having an active hydrogen of the urethane resin with a specific compound. It is not limited.

As the polyurethane resin having an anionic group, at least one of a polyol having a molecular weight of 300 to 20,000, a polyisocyanate, a chain extender having a reactive hydrogen atom, a group reactive with an isocyanate group, and an anionic group is used. Resins composed of individual compounds are preferred.

In the present invention, the effect is exhibited by using a specific acrylic resin, but as a more preferable form,
It is possible to introduce a functional group such as a carboxyl group, a hydroxyl group, a methylol group or an amide group into the acrylic resin by copolymerization, and mix a functional group capable of undergoing a crosslinking reaction with this functional group. In this case, by using the above-mentioned specific acrylic resin, the effect of increasing the reaction efficiency with the crosslinking agent and improving the water resistance and heat resistance of the laminated film is exhibited. The type of the cross-linking agent is not particularly limited as long as it causes a cross-linking reaction with the functional group, for example, a melamine-based cross-linking agent, an oxazoline-based cross-linking agent, an isocyanate-based cross-linking agent,
Epoxy type crosslinking agents, aziridine type crosslinking agents, methylolated or alkylolated urea type, acrylamide type, polyamide type resins, amide epoxy compounds, various silane coupling agents, various titanate type coupling agents and the like can be used. In particular, a melamine-based crosslinking agent,
Oxazoline crosslinking agents are preferred.

Polystyrene sulfonic acid and / or its salt has been used to impart an antistatic function. Usually, when this polymer is dispersed in an acrylic resin, the polarity of the polymer surface is Due to the difference, the acrylic resin and polystyrene sulfonic acid and / or their salts have a separated structure in the finally formed coating film, and this tendency tends to occur particularly in the case of the so-called in-line coating method applied in the film manufacturing process. Remarkably expressed. When this phenomenon occurs, if the coating thickness is increased or a large amount of polystyrene sulfonic acid and / or its salt is added to improve the antistatic function, the coating film is easily cracked and the coating film is easily scraped. However, there is a problem that the transparency is lowered, or polystyrene sulfonic acid and / or its salt having strong hydrophilicity forms an aggregate and is dispersed in a macro, so that it absorbs moisture and blocks. These problems can be improved by uniformly finely dispersing polystyrene sulfonic acid and / or a salt thereof in an acrylic resin matrix, which is a preferred embodiment of the present invention. That is, by dispersing polystyrene sulfonic acid and / or a salt thereof in an acrylic resin having the above-mentioned specific structure, a very uniform fine dispersion structure is obtained even after the coating film is formed, and a coating film having a remarkably excellent antistatic effect is obtained. Is possible and preferable.

Here, the polystyrene sulfonic acid and / or its salt means that after polystyrene is sulfonated and sulfonated, it is neutralized with a hydroxide of monovalent alkali metal or alkaline earth metal such as potassium, sodium or lithium. As a metal counterion, neutralized with ammonia as an ammonium counterion, or an anionic polymer obtained by polymerizing styrene sulfonic acid or styrene sulfonate (the above metal and ammonium as salts). is there. It is preferable to use this polystyrene sulfonic acid and / or its salt as a homopolymer in order to exhibit the antistatic function, but it may be copolymerized with various monomers as described in the acrylic resin constituting monomer.

The above-mentioned acrylic resin and resins other than acrylic resin can be mixed in an arbitrary ratio, but preferably the acrylic resin is 3% by weight or more, more preferably 10% by weight or more in the constituents of the laminated film. , Most preferably 2
It is preferably 0% by weight or more for uniform dispersion.

In the present invention, the dispersion index in the plane direction of the laminated film is 2 to 20. This dispersion index is obtained by a measurement method and a calculation formula separately determined when observing the dispersibility parallel to the laminated film surface in a laminated film made of a composite component containing an acrylic resin, and the value is 2 to 2. 20, preferably 2 to 15, more preferably 2 to 8. Within these ranges, the dispersibility is good, and a laminated film having a uniform structure can be obtained, and there is no coating unevenness, and adhesion, scratch resistance, blocking resistance, transparency, etc. are excellent. The effect is obtained. When the dispersion index is more than 20, poor transparency of the resins occurs due to poor dispersion of the resins, and the effect expected by mixing becomes insufficient.

In the laminated film of the present invention, various additives such as an antioxidant, a heat stabilizer, a weather stabilizer, an ultraviolet absorber, an organic compound, etc. are used within the range where the effect of the present invention is not impaired. The lubricants, pigments, dyes, organic or inorganic fine particles, fillers, antistatic agents, nucleating agents, etc. may be added.
In particular, a layered film to which inorganic or organic fine particles are added is preferable because slipperiness and blocking resistance are improved. In this case, as the inorganic particles to be added, silica, colloidal silica, alumina, alumina sol, kaolin,
Talc, mica, calcium carbonate, etc. can be used.

The thickness of the laminated film of the present invention is not particularly limited and may be arbitrarily set according to the purpose, but is usually 0.001 to 5 μm, more preferably 0.01 to 2 μm.
In many cases m is applied.

The laminated film of the present invention may be applied to a biaxially stretched polyester film, but when the laminated film is provided by a so-called in-line coating method in which it is applied in the film production process, The superiority is remarkably expressed. The coating method is not particularly limited, and a known method such as a reverse coating method, a gravure coating method, a rod coating method, a bar coating method, a die coating method or a spray coating method can be used.

The laminated polyester film obtained by the present invention has no coating unevenness, adhesiveness, and compatibility thereof,
It is a laminated polyester film having excellent scratch resistance, blocking resistance, transparency and the like, and can be suitably used for magnetic recording materials, optical materials, graphic materials, labels, printing materials and the like.

[Method of measuring characteristics and method of evaluating effects]
The method of measuring characteristics and the method of evaluating effects in the present invention are as follows. (1) Dispersion Index in Plane Direction of Laminated Film An ultrathin film section is cut out perpendicularly to the film surface and the laminated film is dyed with RuO ₄ so that the cross-sectional structure of the laminated film can be observed from the laminated polyester film. This Ru
Using a transmission electron microscope (H-7100FA type manufactured by Hitachi, Ltd.), the laminated film portion of the O ₄ -stained ultrathin film section was observed with a cross-sectional observation image with an observation magnification of 100,000 times under the condition of an accelerating voltage of 100 kv. Take a picture. The light and shade of the cross-section of the laminated film at 100,000 times was captured as a digital image with a scanner at 200 dpi, and analyzed with image analysis software (V10 for Windows (R) manufactured by Toyobo Co., Ltd.).

In the analysis method, the thickness of the laminated film in the digital image is evenly divided into 10 parallel to the surface direction, and the light and shade of 2000 nm length for each is taken as an image analysis chart in which the vertical axis is the density and the horizontal axis is the measurement length. It was created. The average density straight line in the measurement range length was written from the density distribution curve of this image analysis diagram, and the distance C from the point A where the straight line intersected with the density distribution curve to the next crossing point B was obtained. The maximum C value is obtained in one concentration distribution curve. This is repeated for 10 divided points, each C is obtained, and the average value D is obtained. In addition, even if the laminated film has uneven thickness or is not a continuous film due to cracks,
When the actual laminated film was not measured, that portion was excluded from the target for calculating the average concentration straight line and the C value.

The dispersion index was calculated from the value calculated above by the following formula.

Dispersion index = (D / 2000) × 100 When the dispersion index is large, that is, when the D value is large, it means that resin species having different dyeing densities form a large aggregate. Indicates that the condition is bad. (2) Transparency A fully automatic direct reading haze computer HGM-2DP (for C light source) (manufactured by Suga Test Instruments Co., Ltd.) was used to measure the haze value, and the average value of 10-point measurement was displayed. At this time, a difference of 3 or less in haze from the polyester film having no laminated film was regarded as good.

Haze value: H (%) = (Td / Tt) × 1
00 Td (%) = [{T4-T3 * (T2 / T1)} / T1] *
100 (diffuse transmittance) Tt (%) = (T3 / T1) × 100 (total light transmittance) (T1: incident light, T2: total light transmitted light, T3: diffused light of device, T4: diffused transmitted light) (3) The blocking resistance laminated films are superposed on each other, and the load (500 g / (3 × 4)
cm ² ), the humidity was adjusted at 40 ° C. and 90% RH for 24 hours, and the peeled state of the portion to which the load was applied was observed. The evaluation standard is
⊚: Peeled off easily and no trace of overlapping remains. ◯: Peeling off easily, but traces of overlapping remain in part. Δ: Peeling is possible, but a trace of overlapping remains. X: The film is cleaved when peeled. And ⊚ and ◯ were evaluated as good. (4) Uneven coating The surface of the laminated film was illuminated with sunlight to observe the appearance.
The evaluation standard is ◯: coating unevenness is not observed. Δ: uneven coating is observed. X: The appearance is significantly impaired due to coating unevenness. Therefore, ◯ was evaluated as good. (5) Adhesive UV Ace SK-2 ink (manufactured by Kuboi Ink Mfg. Co., Ltd.) was used as the ultraviolet curable ink and was applied on the laminated film by a roll coating method to a thickness of about 1.5 μm. Then, using a UV lamp having an irradiation intensity of 80 W / cm, irradiation was performed for 5 seconds at an irradiation distance (distance between the lamp and the ink surface) of 12 cm to form a printing layer. After humidity conditioning at 23 ° C. and 65% RH for 1 day, 100 1 mm ² cross cuts were put in the printing layer, cellophane tape manufactured by Nichiban Co., Ltd. was stuck on it, and pressed using a rubber roller (load). After 3 round trips at 20N),
It was peeled in the direction of 90 degrees.

The adhesiveness was evaluated by the number of remaining printed layers. The judgment criteria are ◎: 100, ◯: 80 to 99,
Δ: 50 to 79, ×: 0 to 49, and ⊚ and ◯ were evaluated as good adhesiveness. (6) After allowing the antistatic film to stand at 23 ° C. and 65% relative humidity for 1 day, a digital ultrahigh resistance / micro ammeter R8340A (manufactured by Advantest Co., Ltd.) was used to apply an applied voltage of 100 V onto the laminated film. It was measured. At this time, 9 × 10 ⁹ Ω / □ or less was determined as good antistatic property. (7) The surface of the scratch-resistant laminated film was evaluated for ease of abrasion when a load of 400 to 600 g was applied and the surface was scratched with a nail. The evaluation standard is ◯: the laminated film is not displaced. Δ: The laminated film is slightly scraped but does not become powdery. X: The laminated film is scraped and becomes powdery.
Therefore, ◯ was evaluated as good.

[0054]

The present invention will be described below with reference to examples.
The present invention is not necessarily limited to this.

Example 1 0.015% by weight of colloidal silica having an average particle size of 0.4 μm and an average particle size of 1.5
P containing 0.005% by weight of colloidal silica of μm
ET pellets (intrinsic viscosity 0.63 dl / g) are vacuum dried, then supplied to an extruder and melted at 285 ° C, extruded into a sheet from a T-shaped die, and the surface temperature is 25 ° C using an electrostatically applied casting method. It was wound around a mirror-casting drum of No. 1 and cooled and solidified to obtain an unstretched film. This unstretched film was heated to 85 ° C. and stretched 3.3 times in the longitudinal direction to obtain a uniaxially stretched film. This film was subjected to a corona discharge treatment in air, and a 25 ° C. laminated film forming coating liquid was applied. The coated uniaxially stretched film is guided to a preheating zone while being held by a clip, dried at 90 ° C, continuously stretched 3.3 times in the width direction in a heating zone of 100 ° C, and further heated in a heating zone of 225 ° C. A heat treatment was performed to obtain a laminated polyester film with crystal orientation completed. At this time, the thickness of the base PET film was 50 μm, and the thickness of the laminated film was 0.15 μm.

The laminated film forming coating solution used here is A1 / B.
It was an aqueous dispersion composed of 1 = 70/30 (weight ratio of solid content). The composition of A1 and B1 will be described later. The evaluation results are shown in Table 1.

(Example 2) A laminated polyester film was obtained in the same manner as in Example 1 except that the coating liquid for forming a laminated film of Example 1 was changed to A2 / B1 = 70/30 (solid content weight ratio). . The results are shown in Table 1.

Example 3 A laminated polyester film was obtained in the same manner as in Example 1 except that the coating liquid for forming a laminated film of Example 1 was changed to A3 / B1 = 70/30 (solid content weight ratio). . The results are shown in Table 1.

Example 4 A laminated polyester film was obtained in the same manner as in Example 1 except that the coating liquid for forming a laminated film of Example 1 was changed to A1 / B2 = 70/30 (solid content weight ratio). . The results are shown in Table 1.

Example 5 A laminated polyester film was obtained in the same manner as in Example 1, except that the coating liquid for forming a laminated film of Example 1 was changed to A1 / B3 = 70/30 (solid content weight ratio). . The results are shown in Table 1.

Comparative Example 1 The procedure of Example 1 was repeated, except that the coating liquid for forming a laminated film of Example 1 was changed to A4 / B1 = 70/30 (solid content weight ratio). The results are shown in Table 1.

Comparative Example 2 The procedure of Example 1 was repeated, except that the coating liquid for forming a laminated film of Example 1 was changed to B1 / B2 = 30/70 (weight ratio of solid content). The results are shown in Table 1.

Comparative Example 3 The procedure of Example 1 was repeated, except that the coating liquid for forming a laminated film of Example 1 was changed to A4 / B2 = 70/30 (solid content weight ratio). The results are shown in Table 1.

Comparative Example 4 The procedure of Example 1 was repeated, except that the coating liquid for forming a laminated film of Example 1 was changed to A4 / B3 = 70/30 (solid content weight ratio). The results are shown in Table 1.

(Comparative Example 5) The procedure of Example 1 was repeated except that the laminated film was not formed. The results are shown in Table 1.

The resin compositions used in Examples and Comparative Examples are as follows. A1: Methyl methacrylate (62 mol%), ethyl acrylate (30 mol%), acrylic acid (2 mol%), N-
Emulsion solution A2 of acrylic resin (emulsion diameter 50 nm) consisting of methylol acrylamide (1 mol%), polyethylene glycol monomethacrylate (3 mol%) having 16 repeating units of ethylene oxide, and 2-sulfoethyl acrylate (2 mol%): methacryl Methyl acidate (62 mol%), ethyl acrylate (30 mol%), acrylic acid (2 mol%), N-
Emulsion solution A3 of acrylic resin (emulsion diameter 50 nm) consisting of methylol acrylamide (1 mol%) and polyethylene glycol monomethacrylate (5 mol%) having 16 repeating units of ethylene oxide: methyl methacrylate (66 mol%), ethyl acrylate (30 mol%), acrylic acid (3 mol%), N-
Emulsion solution A4 of acrylic resin (emulsion diameter 50 nm) consisting of methylol acrylamide (1 mol%): methyl methacrylate (66 mol%), ethyl acrylate (30 mol%), acrylic acid (3 mol%), N-
Emulsion solution of copolymer (emulsion diameter 120 nm) consisting of methylol acrylamide (1 mol%) B1: Aqueous solution of polystyrenesulfonic acid ammonium salt (weight average molecular weight 70,000) B2: Isophthalic acid (90 mol%), 5-sodium sulfo Isophthalic acid (10 mol%), ethylene glycol (10 mol%), diethylene glycol (90 mol%)
Polyester resin water dispersion B3 consisting of: Polyurethane resin water dispersion "HYDRAN" AP10
(Manufactured by Dainippon Ink and Chemicals, Inc.)

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[Table 1]

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[Effects of the Invention] Each component in the laminated film on the polyester film is uniformly dispersed, there is no coating unevenness, and the adhesiveness,
A laminated polyester film having excellent scratch resistance, blocking resistance, and transparency can be provided.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B29L 9:00 B29L 9:00 F term (reference) 4F100 AK01B AK12 AK25B AK41A AL05B AL07 AT00A BA02 CC01B EJ37 JB05B JL05 JL11 JN01 4F210 AA24 AG01 AG03 QC06 QD08 QD10 QG01 QG15 QG18

Claims (5)

[Claims] 1. A laminated polyester film in which an acrylic resin and a laminated film containing a resin other than an acrylic resin are provided on at least one side of a polyester film, and the dispersion index in the plane direction of the laminated film is 2 to 20. A laminated polyester film characterized in that. 2. The laminated polyester film according to claim 1, wherein the resin other than the acrylic resin has a hydrophilic group. 3. A monomer component constituting an acrylic resin,
The laminated polyester film according to claim 1 or 2, which has two or more alkylene oxide units. 4. A monomer component constituting an acrylic resin,
The laminated polyester film according to any one of claims 1 to 3, which has two or more alkylene oxide units and / or has an anionic group. 5. The laminated film is obtained by applying a water-based coating liquid to a polyester film before completion of crystal orientation, stretching the film in at least one direction, and then subjecting it to heat treatment. The laminated polyester film according to any one of 1.