JP2005144982A - Laminated polyester film for dummy can - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated polyester film which has an undercoated layer having transparency, an anti-static property, adhesion to ink and scraping resistance at the same time, and is suitable for a film material for a dummy can . <P>SOLUTION: The laminated film has an anti-static film composed of a resin composition of 20 to 90 wt.% of an acrylic resin (1) having a glass transition temperature of 0 to 100°C, 5 to 40 wt.% of a polyester resin (2) having a glass transition temperature of 20 to 200°C and 5 to 40 wt.% of an anti-static agent and having a dry thickness of 0.01 to 5μm, the anti-static film laminated on at least one surface of a polyester film, wherein surface resistivity is not more than 5×10<SP>10</SP>(Ω/square), a haze value is not more than 4%, a thermal shrinkage ratio is 1.0 to 2.5% in a mechanical direction at 150°C, and the thermal shrinkage ratio is 3.5 to 5.5% in the mechanical direction at 190°C. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a laminated polyester film for a dummy can, and more particularly relates to a laminated polyester film for a dummy can which is excellent in abrasion resistance in a screen printing process and further excellent in transparency and antistatic properties.

  A dummy can is a film can that is displayed in a can vending machine, and is usually made by printing a can design on a film and molding it into a can shape by heat. The film for dummy cans used in the manufacture of this dummy can requires transparency and prevention of printing misalignment from the viewpoint of product aesthetics, and antistatic properties from the standpoint of preventing charging in the printing process and preventing adhesion of dust. Is required, adhesiveness to ink is required, abrasion resistance is required from the viewpoint of preventing abrasion in the printing process, and easy moldability is also required.

  By the way, polyester films, especially polyethylene terephthalate biaxially oriented films are excellent in transparency, dimensional stability, mechanical properties, electrical properties, gas barrier properties, heat resistance, chemical resistance, etc. It is used as a base material for photosensitive materials, drawing materials, electrophotographic materials, and printing materials using insulating materials, silver salts, diazo compounds, photosensitive resins, and the like. In these applications, the adhesiveness between the two is usually improved by providing an undercoat layer between the polyester film (support) and the surface layer material.

  In addition, it can avoid problems in the working environment as a coating agent for improving the adhesion between polyester and metal foils and various plastics (especially hydrophilic resins such as gelatin), and the advantage that no explosion-proof equipment is required. It has been proposed to use water-soluble or water-dispersible polyester copolymers. For example, Patent Document 1 discloses a polyester comprising a compound containing an ester-forming sulfonic acid metal base-containing compound in an amount of 8 mol% or more based on the total acid component and a polyethylene glycol of 20 mol% or more based on the total glycol component. It is described for use as a sizing agent for fibers. However, even when this copolymer is used in the undercoat layer, there is a problem that the water resistance, that is, the water resistance of adhesion is inferior, and it is unsuitable for the use of the undercoat layer.

  Patent Document 2 describes a water-soluble polyester using a saturated linear aliphatic dicarboxylic acid having 4 to 8 methylene groups as an acid component for the purpose of improving adhesiveness. However, even when this water-soluble polyester is used for the undercoat layer, there is a problem that the water resistance of the undercoat layer is insufficient. Furthermore, Patent Document 3 describes that a polyester resin for film formation is made into a substantially water-insoluble aqueous dispersion for application to improve water resistance. However, since this water-based dispersion contains a water-soluble organic solvent, problems such as work environment remain. Patent Document 4 is substantially the same as Patent Document 3, except that the final aqueous dispersion does not contain an organic solvent. However, since an organic solvent is used in the process of preparing the aqueous dispersion, the aqueous dispersion preparation process becomes complicated in addition to problems in the working environment, which is not preferable in practice.

  It has also been proposed to provide an undercoat layer having excellent transparency and antistatic properties on the film surface. For example, Patent Document 5 discloses a technique for providing an undercoat layer that is transparent, has antistatic properties, and satisfies adhesiveness. However, since this technology uses a substantially water-insoluble polyester copolymer, it is necessary to prepare an aqueous dispersion after dissolving in a water-soluble organic solvent. However, there are various problems such as the necessity of taking measures for the explosion of the stretching device and environmental pollution. In addition, the undercoat layer obtained by applying this aqueous dispersion is rich in water resistance, but has poor adhesion to the hydrophilic colloid layer.

  Patent Document 6 discloses a composite film in which a polymer having a specific sulfonic acid or a salt thereof is laminated on the film surface as an easily adhesive polyester film excellent in alkali resistance, water resistance, transparency and antistatic property. It is disclosed. However, in order to orient the surface layer sulfonic acid and / or salt thereof and obtain the desired performance, it is necessary to stretch under specific conditions, so the process control becomes complicated and is not practically preferable. Absent. For this reason, since the stretching process is placed in pressurized water or in the presence of pressurized steam, there is also a problem that there is a work risk.

  Patent Document 7 discloses a technique for forming a subbing layer by applying a specific resin composition to the surface of a polyester film in order to improve adhesion to a hydrophobic layer made of a magnetic recording material or the like. Yes. However, with this technique, it has been difficult to impart excellent transparency and antistatic properties to the undercoat layer, and to simultaneously impart adhesion to a hydrophilic polymer resin to polyvinyl alcohol, gelatin and the like. .

  In addition, a technology that forms an undercoat layer on the polyester film surface with transparency, antistatic properties, and adhesion to ink at the same time using an acrylic resin / polystyrene sulfonate coating solution without using organic solvents. However, the abrasion resistance is poor, and the undercoat layer peels off during the printing process, which is not preferable in practice.

Japanese Examined Patent Publication No. 47-40873 Japanese Patent Publication No.56-5476 Japanese Examined Patent Publication No. 61-58092 JP 60-248231 A Japanese Patent Publication No. 4-10858 Japanese Patent Publication No. 7-45234 Japanese Patent Publication No.1-30622

  The present invention has been made to solve the above-mentioned problems of the prior art, that is, a subbing layer having transparency, antistatic properties, adhesion to ink, and abrasion resistance at the same time is provided. The main object is to provide a laminated polyester film suitable as a film material for cans.

In order to achieve this object of the present invention, the present invention provides (1) 20 to 90% by weight of an acrylic resin having a glass transition point of 0 to 100 ° C. and (2) a glass transition point of 20 on at least one side of a polyester film. An antistatic coating film comprising a resin composition comprising 5 to 40% by weight of a polyester resin at ˜200 ° C. and (3) 5 to 40% by weight of an antistatic agent and having a dry thickness of 0.01 to 5 μm is formed. Laminated film having a surface resistivity of 5 × 10 ¹⁰ (Ω / □) or less, a haze of 4% or less, a heat shrinkage in the machine direction at 150 ° C. of 1.0 to 2.5%, and 190 ° C. Is characterized by a laminated polyester film for a dummy can having a heat shrinkage in the machine direction of 3.5 to 5.5%.

The glass transition point here is the temperature at which the micro Brownian motion starts.
The antistatic coating is preferably a coating formed by applying an aqueous liquid and drying.

  The laminated polyester film for dummy cans according to the present invention is superior in transparency, antistatic properties and abrasion resistance as compared with conventional ones, and is also excellent in easy moldability and printing misalignment resistance. As well as suitable characteristics.

  The laminated polyester film of the present invention has a specific antistatic coating formed on at least one side of a polyester film (base material). The polyester film used as a base material is composed of a linearly oriented polyester with crystal orientation synthesized from an aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof.

  Specific examples of the saturated polyester include polyethylene terephthalate, polyethylene isoterephthalate, polybutylene terephthalate, poly (1,4-cyclohexylenedimethylene terephthalate), polyethylene-2,6-naphthalene dicarboxylate, and the like. Polymers or blends of these with a small proportion of other resins are also included. Among these, polyethylene terephthalate and polyethylene-2,6-naphthalenedicarboxylate are particularly preferable. Moreover, 10-400 micrometers is preferable and, as for the thickness of the polyester film of a base material, More preferably, it is 20-250 micrometers. If the thickness is too thin, a problem may occur in the mechanical strength. If it is too thick, the haze increases and transparency may be impaired.

  The antistatic film provided on at least one surface of the laminated polyester film for dummy cans in the present invention is obtained by applying a coating liquid containing the resin composition specified in the present invention as a solid content to a predetermined surface of the polyester film of the substrate. It can be formed by drying. The dry thickness of the antistatic coating is 0.01 to 5 μm, more preferably 0.1 to 2 μm. When the dry thickness is too thin, a sufficient antistatic function may not be obtained, and when it is too thick, the haze increases and transparency may be impaired.

  In order to form the antistatic film in the laminated polyester film of the present invention, any known coating method can be applied as a method of applying the coating solution. For example, a roll coating method, a gravure coating method, a reverse coating method, a spray coating method, an air knife coating method, a bar coating method, an impregnation method, and a curtain coating method can be applied alone or in combination.

  The coating solution is preferably an aqueous solution in which a solid content is melted or dispersed in an aqueous solvent, because of problems such as avoiding problems in the working environment and eliminating the need for explosion-proof equipment.

  The antistatic coating in the laminated film of the present invention comprises (1) 20 to 90% by weight of an acrylic resin having a glass transition point of 0 to 100 ° C., and (2) 5 to 40% of a polyester resin having a glass transition point of 20 to 200 ° C. % And (3) a resin composition comprising 5 to 40% by weight of an antistatic agent. Therefore, the coating composition for forming the antistatic coating film contains the resin composition as a solid content.

  As the acrylic resin contained in the coating solution, those having alkyl acrylate or alkyl methacrylate as the main component are preferable, and water-soluble or water-dispersible acrylic resins are preferable.

  A vinyl monomer that is copolymerizable with alkyl acrylate or alkyl methacrylate and has a functional group is preferably included as a copolymer component because it imparts hydrophilicity to the resin and improves the water dispersibility of the resin. Moreover, what has a functional group which makes affinity with the polyester-type resin mix | blended as a coating agent favorable is preferable. Preferred functional groups include carboxyl groups or salts thereof, acid anhydride groups, sulfonic acid groups or salts thereof, amide groups or alkylolated amide groups, amino groups (including substituted amino groups), or alkylolated groups. Amino groups or salts thereof, hydroxyl groups, epoxy groups and the like.

  Examples of the alkyl group in the alkyl acrylate or alkyl methacrylate include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, lauryl group, and stubrel. Group, cyclohexyl group and the like.

  As the vinyl monomer having a functional group copolymerizable with alkyl acrylate or alkyl methacrylate, the following compounds having a functional group such as a reactive functional group, a self-crosslinkable functional group and a hydrophilic group can be used.

  Examples of the compound having a carboxyl group or a salt thereof or an acid anhydride group include acrylic acid, methacrylic acid, itaconic acid, maleic acid, crotonic acid, metal salts of these carboxylic acids with sodium, ammonium salts, maleic anhydride, etc. Can be given.

  Examples of the compound having a sulfonic acid group or a salt thereof include vinyl sulfonic acid, styrene sulfonic acid, metal salts of these sulfonic acids with sodium, ammonium salts, and the like.

  Examples of the compound having an amide group or an alkylolated amide group include acrylamide, n-methyl methacrylamide, methylol acrylamide, methylol methacrylamide, ureido vinyl ether, β-ureido isobutyl vinyl ether, ureido ethyl acrylate and the like.

  Examples of the compound having an amino group or an alkylolated amino group or a salt thereof include diethylaminoethyl vinyl ether, 2-aminoethyl vinyl ether, 5-aminopropyl vinyl ether, 2-aminobutyl vinyl ether, dimethylaminoethyl methacrylate, dimethylaminoethyl. Examples include vinyl ethers, those obtained by methylolation of their amino groups, quaternary chlorination with alkyl halides, dimethyl sulfate, sultone, and the like.

  As the compound having a hydroxyl group, β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate, β-hydroxyvinyl ether, s-hydroxypentyl vinyl ether, 4-hydroxyhexyl vinyl ether, polyethylene glycol Examples include monoacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monoacrylate, and polypropylene glycol monomethacrylate.

  Examples of the compound having an epoxy group include glycidyl acrylate and glycidyl methacrylate.

  The acrylic resin used by this invention is a thing with a glass transition point of 0-100 degreeC among above-described acrylic resins. When the glass transition point is too low, blocking may occur when the films are brought into close contact with each other, and when too high, the adhesion with the ink may be impaired.

  The ratio of the acrylic resin in the resin composition constituting the antistatic coating is 20 to 90% by weight, preferably 30 to 70% by weight. If the ratio is too low, the adhesion to the ink may be impaired, and if it is too high, the abrasion resistance in the printing process may be impaired.

  The polyester resin contained in the coating solution is a resin polymerized from an acid component and a glycol component. The acid component includes terephthalic acid, isophthalic acid, phthalic acid, 1,4-cyclohexanedicarboxylic acid, and adipic acid. , Sebacic acid, phenylindanedicarboxylic acid, dimer acid and the like. As the glycol component, fatty acid, alicyclic, aromatic diol and the like can be used. Examples thereof include ethylene glycol, 1,4-butanediol, diethylene glycol, triethylene glycol, 1,4-cyclohexanedimethanol, p. -Xylene diol etc. are used and polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc. are used as an example of poly (oxyalkylene) glycol.

  The polyester having a sulfonate group can be produced by copolymerizing a compound having a sulfonate group in addition to the above-described polyester-forming component (acid component or glycol component).

  Examples of the compound having a sulfonate group include metal salts such as sulfoisophthalic acid, sulfoterephthalic acid, sulfonaphthalene-2,6-dicarboxylic acid, and ester-forming derivatives thereof. The metal of the metal salt is preferably lithium, sodium, potassium, magnesium or the like. Among these, very suitable compounds are 5-sodiosulfoisophthalic acid or 5-sodiosulfodimethylisophthalate.

  Another method for introducing a sulfonate group into polyester is to sulfonate the unsaturated group of the polyester containing an ester-forming aliphatic unsaturated compound as a copolymerization component with a sulfonating agent such as sodium bisulfite or sodium metabisulfite. A method can be illustrated.

  When the coating liquid is an aqueous liquid, the sulfonate group in the polyester resin must be present in an amount necessary to make the resin water-soluble or water-dispersible. The dicarboxylic acid having a sulfonate group is dicarboxylic acid. It is preferable to use in the range of 8 to 20 mol% in the acid.

  The polyester resin used in the present invention has a glass transition point of 20 to 200 ° C. among the polyester resins described above. When the glass transition point is too low, blocking may occur when the films are brought into close contact with each other.

  The proportion of the polyester resin in the resin composition constituting the antistatic coating is 5 to 40% by weight, preferably 15 to 35% by weight. When the ratio is too low, the abrasion resistance in the printing process may be impaired, and when it is too high, the adhesion with the ink may be impaired.

  Examples of the antistatic agent contained in the coating liquid include low-molecular substances and high-molecular substances having antistatic properties, for example, vinyl copolymers having a sulfonic acid metal salt in the molecule, alkylsulfonic acid metal salts, betaines, Acrylic polymer having a quaternary ammonium base, ion-conductive polymer such as ionene polymer, phosphate and phosphate, metal oxide such as tin oxide-antimony oxide, metal such as alkoxysilane, alkoxytitanium and alkoxyzirconium One or more selected from alkoxides and derivatives thereof, coated carbon, coated silica and the like can be used.

  The ratio of the antistatic agent in the resin composition constituting the antistatic coating is 5 to 40% by weight, preferably 15 to 35% by weight. If the ratio is too low, the antistatic property may be poor, and if it is too high, the haze may increase and the transparency may be impaired.

  The laminated polyester film of the present invention has a heat shrinkage in the machine direction at 150 ° C. of 1.0 to 2.5%, preferably 1.0 to 2.0%. If the thermal shrinkage is too low, the moldability may be poor, and if it is too high, printing misalignment may occur in the printing process. Moreover, the heat shrinkage rate in the machine direction at 190 ° C. is 3.5 to 5.5%, preferably 3.5 to 5.0. If the thermal shrinkage is too low, the moldability may be poor, and if it is too high, printing misalignment may occur in the printing process. Note that the heat shrinkage in the machine direction at 150 ° C. and the heat shrinkage in the machine direction at 190 ° C. are values obtained by the following measurement method.

In accordance with JIS-C-2151, a sample obtained by cutting a polyester film into a size of 300 mm × 300 mm was heat-treated in a hot air oven at 150 ° C. for 30 minutes and 190 ° C. for 20 minutes, and the dimensional difference before and after the treatment was read. Thus, the thermal shrinkage rate was obtained from the following formulas. A universal photographing machine equipped with a reader was used for dimension measurement, and reading was performed with an accuracy of 1 μm.
Thermal shrinkage = ((length before treatment−length after treatment) / length before treatment) × 100 (%)

Furthermore, the surface specific resistance is 5 × 10 ¹⁰ (Ω / □) or less, preferably 5 × 10 ⁹ (Ω / □) or less. When the surface specific resistance is too high, the printing process may be stopped due to the charging of the film, or dust may be easily attached when the product is used. In addition, the surface specific resistance of a film is a value calculated | required by the following measuring method.

  The polyester film is cut to a size of 110 mm in width and 110 mm in length and left for 24 hours or longer under conditions of 23 ± 3 ° C. and 65 ± 10% RH, and then a digital super high resistance meter manufactured by Advantest Corporation is used. , Measured according to JIS-C-2151.

  In order to set the value of the surface specific resistance to the predetermined level described above, the amount and type of the antistatic agent in the coating solution may be adjusted.

  Furthermore, the haze is 4% or less, preferably 3.5% or less. If it is too high, it is not practically preferable as a product from the viewpoint of aesthetics. Methods for lowering haze include reducing the coating thickness within the aforementioned range and reducing the amount of antistatic agent added. The haze of the film is a value measured according to JIS-K-7105 using a haze meter manufactured by Suga Test Instruments.

  Moreover, in the range which does not lose | disappear the effect of this invention, additives, such as an inorganic and organic particle | grains, can be mixed, for example, for a slip improvement. Examples of the inorganic particles include kaolin, silica, colloidal silica, calcium carbonate, titanium oxide, barium salt, alumina, molybdenum sulfide, carbon black, and zirconium. Examples of the organic particles include a copolymer of methyl methacrylate and ethylene glycol bismethacrylate.

  The laminated polyester film of the present invention is produced by a method in which the above-described coating solution is applied to one or both sides of the film, dried and further stretched in the uniaxial stretching stage in the course of producing the biaxially oriented polyester film. be able to. Although the method for making the heat shrinkage rate in the machine direction of the laminated film obtained into the above-mentioned desired level is not particularly limited, the following method is preferable.

  That is, an unstretched polyethylene terephthalate film obtained by a conventional method is heated to 70 to 90 ° C. and stretched 2.5 to 3.5 times in the machine axis direction to obtain a uniaxially stretched film. Corona discharge treatment is performed on both surfaces of the film in an air atmosphere, and the above-described coating solution is applied to both surfaces of the film. Subsequently, this uniaxially stretched film was introduced into a preheating zone heated to 90 to 120 ° C., dried, and then continuously held by a clip in a heating zone of 90 to 150 ° C. to 2.0 to 4.0 in the width direction. The film is stretched twice and subsequently subjected to heat treatment for 1 to 60 seconds while performing a relaxation treatment of 0 to 5% in the width direction in a heating zone of 190 to 230 ° C.

Hereinafter, the present invention will be further described with reference to examples.
In the following examples and comparative examples, the following resins and antistatic agents were used.

Acrylic resin: copolymer (aqueous emulsion) polymerized from alkyl acrylate and alkyl methacrylate (composition ratio 50:50) having a glass transition point of about 40 ° C. and a particle size of about 50 nm
Polyester resin: polyester copolymer having a secondary transition point of about 80 ° C. and polymerized from an acid component (terephthalic acid, 5-sodium isophthalic acid is 90:10) and a diol component (ethylene glycol, diethylene glycol is 95: 5) Coalescence

Antistatic agent: Ammonium salt of polystyrene sulfonic acid (molecular weight 10,000)
Colloidal silica (particle size 140nm)
Organic particles: Copolymerized from methyl methacrylate and ethylene glycol bismethacrylate (composition ratio 50:50) having a particle size of about 5μ Surfactant: Aliphatic fluorosurfactant, ethylene glycol monotertiary butyl ether , A mixture of water in a ratio of 10:60:30

In the following examples and comparative examples, the abrasion resistance of the film was determined by the following method.
A polyester film is made into a strip-like sample with a width of 10 mm, and the sample surface is run for 30 seconds at a load of 50 g and a speed of 4 m / min so that the sample contacts a guide pin (manufactured by SUS) using a shaving tester. Was determined according to the following criteria.

○: The scratch on the film of the sample after the test is less than 0.5 mm in width and less than 40 mm in length, and further less than 6.
X: The scratch of the film of the sample after the test is 0.5 mm or more in width and 40 mm or more in length.

[Example 1]
Acrylic resin / antistatic agent / polyester resin / colloidal silica / organic particles / surfactant = 50/25/25 / 0.3 / 0.5 / 0.03 ratio of water dispersion with a solid content concentration of 4.5% A liquid was prepared to be an aqueous liquid A.

  On the other hand, polyethylene terephthalate pellets (IV = 0.651) were sufficiently vacuum-dried, supplied to a melt extruder, melted at 275 ° C., filtered through a 10 μm cut metal sintered filter, and then sheeted from a T-type die. It was extruded into a shape and wound around a cooling drum at 30 ° C. to be cooled and solidified. During this time, in order to improve the adhesion between the sheet and the surface of the cooling drum, a wire electrode was disposed on the sheet portion and a DC current of 10 kv was applied. The unstretched polyethylene terephthalate film thus obtained was heated to 85 ° C. and stretched 2.9 times in the machine axis direction to obtain a uniaxially stretched film. Both surfaces of this film were subjected to corona discharge treatment in an air atmosphere, and the aqueous liquid A was applied to both surfaces of the film. Subsequently, this uniaxially stretched film is guided to a preheating zone heated to 105 ° C., dried, and continuously gripped by a clip in a heating zone of 105 to 110 ° C. and stretched 3.1 times in the width direction. A laminate having a thickness of 150 μm in which a coating layer having a dry film thickness of 0.17 μm was formed on both sides by performing a heat treatment for 10 seconds while performing a relaxation treatment of 2.6% in the width direction in a heating zone of 205 to 215 ° C. A polyethylene terephthalate film was produced.

[Example 2]
Acrylic resin / antistatic agent / polyester resin / colloidal silica / organic particles / surfactant = 50/25/25 / 0.3 / 0.5 / 0.03 ratio of water dispersion with a solid content concentration of 6.0% A liquid was prepared to be an aqueous liquid B. A laminated polyethylene terephthalate film having a thickness of 150 μm was produced in the same manner as in Example 1 except that the aqueous liquid B was used for coating on the film surface, and a coating layer having a dry coating thickness of 0.23 μm was formed on both sides. did.

[Example 3]
Acrylic resin / antistatic agent / polyester resin / colloidal silica / organic particles / surfactant = 50/25/25 / 0.3 / 0.5 / 0.03 water dispersion with a solid content of 7.5% A liquid was prepared and designated as an aqueous liquid C. A laminated polyethylene terephthalate film having a thickness of 150 μm was produced in the same manner as in Example 1 except that the aqueous liquid C was used for coating on the film surface, and a coating layer having a dry coating thickness of 0.29 μm was formed on both sides. did.

[Comparative Example 1]
An aqueous dispersion having a solid content concentration of 4.5% is prepared at a ratio of acrylic resin / polyester resin / colloidal silica / organic particles / surfactant = 50/50 / 0.3 / 0.5 / 0.03, and is aqueous. It was set as the liquid D. A laminated polyethylene terephthalate film having a thickness of 150 μm was produced in the same manner as in Example 1 except that the aqueous liquid D was used for coating on the film surface, and a coating layer having a dry film thickness of 0.17 μm was formed on both sides. did.

[Comparative Example 2]
An aqueous dispersion having a solid content concentration of 4.5% was prepared at a ratio of polyester resin / antistatic agent / organic particles / surfactant = 75/25 / 0.5 / 0.03, and designated as aqueous liquid E. A laminated polyethylene terephthalate film having a thickness of 150 μm was produced in the same manner as in Example 1 except that the aqueous liquid E was used for coating on the film surface, and a coating layer having a dry film thickness of 0.17 μm was formed on both sides. did.

[Comparative Example 3]
An aqueous dispersion having a solid content concentration of 4.5% was prepared at a ratio of acrylic resin / antistatic agent / organic particles / surfactant = 75/25 / 0.3 / 0.03 to obtain an aqueous liquid F. A laminated polyethylene terephthalate film having a thickness of 150 μm was produced in which a coating layer having a dry film thickness of 0.17 μm was formed on both sides in the same manner as in Example 1 except that the aqueous liquid E was used for coating on the film surface. .

[Comparative Example 4]
A uniaxially stretched film was produced under the same conditions as in Example 1. Both surfaces of this film were subjected to corona discharge treatment in an air atmosphere, and the aqueous liquid A used in Example 1 was applied to both surfaces of the film. Subsequently, this uniaxially stretched film was led to a preheating zone heated to 105 ° C., dried, and then continuously gripped by a clip in a heating zone of 105 ° C. to 110 ° C. and stretched 3.5 times in the width direction. A heat treatment was performed for 10 seconds in a heating zone of 220 ° C. to 235 ° C. with a relaxation treatment of 1.7% in the width direction, and a coating layer having a dry film thickness of 0.17 μm was formed on both sides, a thickness of 150 μm A laminated polyethylene terephthalate film was produced.

  Table 1 shows the solid content composition and concentration in the coating solutions used in the above Examples and Comparative Examples. Moreover, the characteristic of the obtained laminated | multilayer film was as Table 2.

  As is clear from Table 2, the laminated films obtained in the examples ensured excellent levels in terms of surface specific resistance, haze, surface specific resistance, and abrasion resistance. Furthermore, since the heat shrinkage rate at 150 ° C. is low and the heat shrinkage rate at 190 ° C. is high, it is excellent in easy moldability and printing misalignment prevention. Therefore, it is optimal for dummy can applications.

  The laminated polyester film of the present invention is useful as a material for producing a dummy can.

Claims (3)

On at least one side of the polyester film, (1) 20 to 90% by weight of an acrylic resin having a glass transition point of 0 to 100 ° C, (2) 5 to 40% by weight of a polyester resin having a glass transition point of 20 to 200 ° C, and (3) A laminated film comprising a resin composition comprising 5 to 40% by weight of an antistatic agent and having an antistatic coating having a dry thickness of 0.01 to 5 μm, having a surface specific resistance of 5 × 10 ¹⁰ (Ω / □) The haze is 4% or less, the heat shrinkage in the machine direction at 150 ° C. is 1.0 to 2.5%, and the heat shrinkage in the machine direction at 190 ° C. is 3.5 to 5.5. % Laminated polyester film for dummy cans. The laminated polyester for a dummy can according to claim 1, wherein the composition ratio of the acrylic resin, the polyester resin, and the antistatic agent in the resin composition is 30 to 70 wt%, 15 to 35 wt%, and 15 to 35 wt%, respectively. the film. The laminated polyester film for a dummy can according to claim 1 or 2, wherein the antistatic coating is a coating formed by applying and drying an aqueous liquid.