JPH11228714A - Polyester film for lamination with metallic sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject film excellent in fabricability, impact resistance, and taste characteristics and desirable for use in a metallic can excellent in taste characteristics and produced by, especially, molding by combining a specified acid component with a specified glycol component. SOLUTION: The polyester film mainly consists of a polyester A comprising an acid component comprising at lest 96 mol.% terephthalic acid and/or naphthalenedicarboxylic acid and a glycol component comprising 0-95 mol.% ethylene glycol and 5-100 mol.% propylene glycol. To attain particularly good state characteristics, it is desirable that the layer A is composited with a layer B mainly consisting of a polyester B comprising an acid component comprising at least 96 mol.% terephthalic acid and/or naphthalenedicarboxylic acid and a glycol component comprising 60-100 mol.% ethylene glycol and 0-40 mol.% propylene glycol.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a polyester film for laminating a metal plate. More specifically, the present invention relates to a polyester film for laminating a metal plate suitable for a metal can produced by molding since it has excellent moldability, impact resistance and taste characteristics.

[0002]

2. Description of the Related Art Conventionally, the inner and outer surfaces of metal cans are coated with various thermosetting resins, such as epoxy and phenol, dissolved or dispersed in a solvent for the purpose of preventing corrosion. Has been widely practiced. However, such a method of coating the thermosetting resin requires a long time for drying the paint, and has unfavorable problems such as a decrease in productivity and environmental pollution due to a large amount of an organic solvent.

As a method of solving these problems, there is a method of laminating a film on a steel plate, an aluminum plate or a metal plate obtained by subjecting the metal plate to various surface treatments such as plating. When a metal can is manufactured by drawing or ironing a laminated metal plate of a film, the film is required to have the following characteristics. (1) Excellent adhesion to a metal plate. (2) It is excellent in moldability and does not generate defects such as pinholes after molding. (3) The polyester film does not peel off, crack or pinhole due to impact on the metal can. (4) The scent component of the contents of the can adsorbs to the film,
The flavor of the contents is not degraded by the eluate from the film (hereinafter referred to as taste characteristics).

Many proposals have been made to solve these requirements. For example, JP-A-64-22530 discloses a polyester film having a specific density and a plane orientation coefficient. Is a copolyester film having a specific crystallinity;
JP-A-978 and JP-A-5-156040 propose a film containing a specific component in order to improve impact resistance. However, these proposals are not necessarily able to comprehensively satisfy the various required characteristics as described above, and can be sufficiently satisfied particularly in applications where both impact resistance and excellent taste characteristics after retort treatment are required. I could not say it was on the level.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide excellent moldability, impact resistance and taste characteristics, and particularly to taste characteristics produced by molding. An object of the present invention is to provide a polyester film for metal plate lamination suitable for an excellent metal can.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is that at least 96 mol% of the acid component is composed of terephthalic acid and / or naphthalenedicarboxylic acid, and the glycol component is 0 to 95 mol% of ethylene glycol and propylene glycol. This is achieved by a polyester film for laminating a metal plate containing polyester A of 5 to 100 mol% as a main component.

As a result of intensive studies, the present invention has found that a film having excellent impact resistance and good taste characteristics even after retorting can be obtained by combining a specific acid component and a glycol component.

[0008]

DETAILED DESCRIPTION OF THE INVENTION Polyester A in the present invention
As a structural unit of the polyester, 96 mol% or more of the acid component is terephthalic acid and / or naphthalenedicarboxylic acid in terms of improving taste characteristics after retorting and improving impact resistance after can-making. And a glycol component comprising 0 to 95 mol% of ethylene glycol and 5 to 100 mol% of propylene glycol.

In applications where impact resistance is particularly important, the glycol component propylene glycol is 10 to 100 mol%.
Is preferred, and particularly preferably 20 to 100 mol%. The introduction of propylene glycol into the polyester A may be copolymerized, or a polyester containing propylene glycol and a polyester not containing propylene glycol may be blended. In that case, a compatibilizer may be used in combination to control the compatibility and the transesterification, and the metal catalyst may be increased. There is no particular limitation on propylene glycol, but 1,3-propanediol is particularly preferred in terms of reactivity and moldability.

Further, the weight ratio of terephthalic acid to naphthalenedicarboxylic acid of polyester A is 60/40 to 95 /.
A value of 5 is preferable because moldability is improved while maintaining taste characteristics. In particular, it is preferable that the weight ratio of terephthalic acid to naphthalenedicarboxylic acid of the polyester A is 60/40 to 90/10, since the moldability becomes particularly good.

The polyester A may be one obtained by copolymerizing another acid component, and the copolymerization amount is preferably 4 mol% or less. Examples of the copolymerizable dicarboxylic acid component include aromatic dicarboxylic acids such as diphenyldicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenoxyethanedicarboxylic acid, 5-sodium sulfoisophthalic acid, and phthalic acid, oxalic acid, succinic acid, and adipine. Examples thereof include aliphatic dicarboxylic acids such as acid, sebacic acid, dimer acid, maleic acid, and fumaric acid; alicyclic dicarboxylic acids such as cyclohexyne dicarboxylic acid; and oxycarboxylic acids such as p-oxybenzoic acid. On the other hand, copolymerizable glycol components include, for example, aliphatic glycols such as butanediol, pentanediol, hexanediol and neopentyl glycol, and cyclohexanedimethanol.
And alicyclic glycols such as ethylene glycol, aromatic glycols such as bisphenol A and bisphenol S, diethylene glycol, polyethylene glycol and the like.

The melting point of the polyester A is preferably 200 ° C. or higher from the viewpoint of heat resistance, and for applications having severe taste characteristics, the melting point is preferably 246 to 280 ° C. The intrinsic viscosity of polyester A is 0.5 to 1
In particular, in applications where impact resistance is required, the intrinsic viscosity is preferably 0.7 to 1.

In the present invention, the above-mentioned layer A containing polyester A as a main component has ethylene terephthalate and / or
Alternatively, it is preferable to combine a polyester having an ethylene naphthalate unit as a main component, since both moldability, taste characteristics, and impact resistance can be achieved. In particular, the main component of polyester B is 96% by mole or more of terephthalic acid and / or naphthalenedicarboxylic acid, and the glycol component is 60 to 100% by mole of ethylene glycol and 0 to 40% by mole of propylene glycol. It is preferable to combine the layer B with the layer A containing polyester A as a main component in order to make the taste characteristics particularly good. It is particularly preferred that the propylene glycol content of the polyester B be 0 to 20 mol%, since the taste characteristics will be good.

A having polyester A as a main component
The layer and the layer B containing polyester B as a main component can be arbitrarily combined. For example, it is possible to composite such as polyester A / polyester B, polyester A / polyester B / polyester A, polyester B / polyester A / polyester B, and the like. When used in metal cans for filling beverages with particularly severe taste characteristics, the ratio of the thickness of polyester A to the thickness of polyester B is 1:
It is preferred that the ratio be 2 to 1:20.

Further, in the present invention, particles may be added to each layer in order to improve the handling of the film and the adhesion to the metal plate.

Specifically, the inorganic particles include wet and dry silica, colloidal silica, aluminum silicate, titanium oxide, calcium carbonate, calcium phosphate,
Examples thereof include barium sulfate, alumina, mica, kaolin, and clay, and calcium phosphate, colloidal silica, and the like are preferable from the viewpoint of adhesiveness.

As the organic particles, various organic polymer particles can be used, and the type of the organic particles is not particularly limited as long as at least a part thereof is insoluble in the polyester. Further, as a material of such particles, polyimide, polyamide imide,
Various materials such as polymethyl methacrylate, formaldehyde resin, phenol resin, cross-linked polystyrene, and silicone resin can be used, but vinyl-based cross-linked polymer particles having high heat resistance and easy to obtain uniform particle size distribution particles Is particularly preferred.

The particles are added to polyester A and / or polyester B and have an average particle size of 0.1.
It is preferable that the average particle diameter be 1 μm or more, particularly for applications where adhesion is important.

The amount of the particles added is 0.01 to 0.5.
It is preferable in terms of moldability that the content be% by weight.

In particular, it is preferable that the ratio of the surface layer particle concentration at 50 nm from the surface to the bulk particle concentration of the layer laminated on the metal plate is 1/5 or less, since the adhesiveness to the metal plate is excellent even after the retort treatment. 50 nm from surface for bulk particle concentration of layer laminated to metal plate
In order to reduce the ratio of the surface layer particle concentration to 1/5 or less, a method of increasing the affinity between the particles and the polyester by controlling the surface treatment of the particles, the polarity of the particle surface, and the functional group, and reducing the amount of the particles added And the like.
Specifically, a method in which the amount of the particles added is 0.2% by weight or less, a method of using particles surface-treated with a polyester or an ethylene glycol component, a method of using spherical particles, and the like are preferable. Crystallization by the particles of the outermost layer is suppressed, so that adhesiveness and moldability are excellent, which is preferable.

The polyester A and the polyester B of the present invention
In the production of, can be used a conventionally known reaction catalyst, a coloring inhibitor, for example, an alkali metal compound, an alkaline earth metal compound, a zinc compound, a lead compound, a manganese compound, a cobalt compound, Examples of the coloring inhibitor such as an aluminum compound, an antimony compound, and a titanium compound include, for example, a phosphorus compound. Preferably, it is preferable to add an antimony compound, a germanium compound, or a titanium compound as a polymerization catalyst at any stage before the production of the polyester is usually completed. Such methods include, for example,
Taking a germanium compound as an example, a method in which a germanium compound powder is added as it is,
As described in JP-A No. 22234, a method of dissolving a germanium compound in a glycol component as a starting material of a polyester and adding the same can be mentioned.

Examples of the germanium compound include germanium dioxide, germanium hydroxide containing crystal water, or germanium alkoxide compounds such as germanium tetramethoxide, germanium tetraethoxide, germanium tetrabutoxide, germanium ethylene glycoloxide, germanium phenolate, and the like. Examples include germanium phenoxide compounds such as germanium β-naphtholate, phosphorus-containing germanium compounds such as germanium phosphate and germanium phosphite, and germanium acetate. Among them, germanium dioxide is preferable.

The antimony compound is not particularly restricted but includes, for example, antimony oxides such as antimony trioxide and antimony acetate. Examples of the titanium compound include, but are not particularly limited to, tetraethyl titanate,
Alkyl titanate compounds such as tetrabutyl titanate are preferably used.

In order to improve the taste characteristics, the content of acetaldehyde in the film is preferably 20 ppm or less,
More preferably 15 ppm or less, particularly preferably 10 ppm or less.
ppm or less is desirable. The method for lowering the content of acetaldehyde in the film is not particularly limited.For example, in order to remove acetaldehyde generated by thermal decomposition when producing a polyester by a polycondensation reaction or the like, the polyester is reduced in pressure or inert. In a gas atmosphere, a method of heat-treating at a temperature not higher than the melting point of the polyester, preferably a method of subjecting the polyester to solid-state polymerization at a temperature of 150 ° C. or higher and a melting point or lower under reduced pressure or an inert gas atmosphere, using a vented extruder And extruding the polymer in a short time by lowering the extrusion temperature as much as possible during melt extrusion of the polymer.

The thickness of the film of the present invention depends on the moldability after lamination on metal, the coating property on metal, the impact resistance,
From the viewpoint of taste characteristics, the thickness is preferably 3 to 50 μm, and more preferably 8 to 30 μm.

The method for producing the film in the present invention is not particularly limited. For example, after drying polyester as required, it is supplied to a known melt extruder, extruded into a sheet from a slit die, and subjected to electrostatic application. In such a manner, it is brought into close contact with the casting drum and solidified by cooling to obtain an unstretched sheet. The unstretched sheet is stretched in the longitudinal direction and width direction of the film and heat-treated to obtain a film having a desired refractive index in the thickness direction. Preferably, a tenter method is preferable in terms of film quality.After stretching in the longitudinal direction, a sequential biaxial stretching method in which the film is stretched in the width direction, a simultaneous biaxial stretching method in which the film is stretched almost simultaneously in the longitudinal direction and the width direction. Is desirable. The stretching ratio is 1.5 in each direction.
~ 4.0 times, preferably 1.8 ~ 3.5 times. Either the stretching ratio in the longitudinal direction or the width direction may be increased,
They may be the same. The stretching speed is 1000% / min.
Preferably, the stretching temperature is equal to or higher than the glass transition temperature of the polyester plus 8%.
Any temperature can be used as long as it is 0 ° C. or lower, but the glass transition temperature + 20 ° C. to 60 ° C. is preferable.

Further, after this, the film is subjected to a heat treatment, which is performed in an oven, on a heated roll, or the like.
It can be performed by any conventionally known method. The heat treatment temperature can be any temperature from 120 ° C. to 250 ° C., but is preferably from 150 to 240 ° C. Further, the heat treatment time can be arbitrarily set, but 0.1 to 60.
Seconds, more preferably 1 to 20 seconds. The heat treatment may be performed while relaxing the film in the longitudinal direction and / or the width direction. Furthermore, re-stretching may be performed once or more in each direction, and then heat treatment may be performed.

It is preferable to improve the adhesiveness by subjecting the film to a surface treatment such as a corona discharge treatment in order to further improve the moldability. At this time, the E value is 5 to 60 W · min / m ² , preferably 10 to 50 W
W · min / m ² . The refractive index in the thickness direction of the layer B containing polyester B as a main component of the composite film of the present invention is preferably 1.5 or more from the viewpoint of lamination properties and moldability. It is particularly preferably 1.51 or more and 1.55 or less in order to achieve both moldability and impact resistance.

Further, the heat shrinkage when the film is heat-treated at 150 ° C. for 30 minutes is preferably 5% or less from the viewpoint of improving laminability and moldability. Particularly preferably, it is 4% or less.

The metal plate of the present invention is not particularly limited.
However, in terms of formability, gold made of iron or aluminum
Plates are preferred. In addition, a place for metal plates made of iron
Inorganic oxide that improves adhesion and corrosion resistance on the surface
Coating layer, eg chromic acid treatment, phosphoric acid treatment, chromic acid /
Phosphoric acid treatment, electrolytic chromic acid treatment, chromate treatment,
A chemical conversion coating layer represented by
You may ask. In particular, as chromium in terms of metal chromium 6.
5-150mg / m^TwoChromium hydrated oxide is preferred,
In addition, a spreadable metal plating layer, such as nickel, tin,
May be provided with zinc, aluminum, gunmetal, brass, etc.
No. 0.5 to 15 mg / m for tin plating ^Two, Nicke
1.8 to 20 g / m for aluminum or aluminum^TwoNo
Those having a jacking amount are preferred.

The polyester film for metal plate lamination of the present invention can be suitably used for coating the inner surface of a two-piece metal can produced by drawing or ironing. Further, it can be preferably used for covering the lid portion of a can because it has good metal adhesion and moldability.

[0032]

The present invention will be described in detail with reference to the following examples. The characteristics were measured and evaluated by the following methods. (1) Intrinsic viscosity of polyester Polyester is dissolved in orthochlorophenol, and 25
Measured in ° C. (2) Refractive index in the thickness direction of the film Measured with an Abbe refractometer using sodium D line (wavelength 589 nm) as a light source. (3) Average particle diameter A cross section of the film was cut to prepare an ultrathin section, photographed with a transmission electron microscope at a magnification of about 5,000 to 20,000, and the circle equivalent diameter of each particle dispersed in polyester A was measured. And the average particle size was determined. (4) Ratio of surface particle concentration to bulk particle concentration Secondary ion mass spectrometer (A-TOMIKA, Germany)
DIDA3000). The depth is measured by a surface profiler (DEKTAK3030ST manufactured by Sloan).
The depth profile of the relative intensities of the constituent elements of the particles is obtained, and the place where the relative intensity is constant is taken as a bulk, and the value at that time and the relative intensity at 50 nm from the surface are obtained. The concentration ratio was used. Representative measurement conditions are described below. Primary ion species: O ₂ ⁺ Primary ion energy: 12 keV Primary ion current: 100 nA Raster area: 300 μm × 300 μm Gate ratio: 50% Analysis area: 150 × 150 μm Detection secondary ion: positive ion Electrospray conditions: 7 kV-3.0 A (F10) Degree of vacuum at the time of measurement: 1.3 × 10 ⁻⁶ Pa HQH: # 14 (5) Thermal shrinkage The shrinkage of the film treated in a hot air oven at 150 ° C. for 30 minutes is measured. It was measured. The measurement was performed in the longitudinal direction and the width direction, and the value in the longitudinal direction (larger one) was described. (6) Formability After laminating a film on a TFS (tin-free steel) steel plate (0.2 mm thick) heated near the melting point of a layer to be laminated on a metal plate at 60 m / min, the film was cooled with hot water at 60 ° C. Then, it was formed by a draw forming machine. Thereafter, the molded can was heated at a melting point of polyester A of −10 ° C. for 120 seconds to perform neck-in processing. The obtained can was subjected to a retort treatment (a treatment with pressurized steam at 125 ° C. for 30 minutes), and a neck portion (see FIG. 1) was observed.

Class A: Almost no change. Class B: A small whitened portion is seen, but there is no problem. Class C: Small darkened portions are observed. (7) Impact resistance 350 g of water having a pH of 6 was filled in a can which was actually made, and the can was covered. After that, the container was left at 40 ° C. for one week. When the bottom of the container dropped, the container was dropped from a height of 30 cm at 45 ° to the concrete ground to give an impact. Mask the inner surface with wax and put 1 in the cup
% Saline solution, left for one day, apply a voltage of 6 V to the electrode and the metal can in the saline solution, and read the current value 3 seconds later.
The average value after can measurement was determined.

Class A: less than 0.3 mA Class B: 0.3 mA or more and less than 0.5 mA Class C: 0.5 mA or more and 1.0 mA or less Class D: 1.0 mA or more

(8) Taste Characteristics A can was filled with tea, subjected to a pressurized steam treatment at 125 ° C. × 30 minutes, and the change in the liquid after cooling to 5 ° C. was visually evaluated according to the following criteria.

No change is observed in the Class A liquid. There is almost no change in the Class B liquid. A slight change is seen in the Class C liquid. A change is seen in the class D liquid.

Example 1 Average particle size 1.7 μm surface-treated with polyester component
Of polypropylene terephthalate containing 0.1% by weight of spherical colloidal silica. The polymerization method is such that manganese acetate is added as a catalyst to dimethyl terephthalate and propylene glycol (1,3-propanediol) to perform a transesterification reaction, and then a slurry in which particles are dispersed in propylene glycol in a reaction product, a titanium catalyst , And a polycondensation reaction by adding phosphoric acid as a heat-resistant stabilizer,
A polyester composition A for a layer was obtained. Polymer physical properties of the polyester composition A were an intrinsic viscosity of 0.78.

Naphthalenedicarboxylic acid copolymerized polyethylene terephthalate containing 0.1% by weight of spherical colloidal silica having an average particle diameter of 1.7 μm and surface-treated with a polyester component (weight of terephthalic acid component: weight of naphthalenedicarboxylic acid = 88: 12) ) Was polymerized. The polymerization method is dimethyl terephthalate, dimethyl ethyl naphthalenedicarboxylic acid, ethylene glycol, after performing a transesterification reaction by adding a titanium catalyst as a catalyst, a slurry in which particles are dispersed in ethylene glycol in the reaction product, a germanium catalyst, and Phosphoric acid was added as a heat stabilizer, and a polycondensation reaction was performed to obtain a polyester composition B for layer B. The polymer properties of the polyester composition B were such that the intrinsic viscosity was 0.1.
70.

The polyester composition A and the polyester composition B obtained as described above are supplied to separate extruders, and are discharged from a die so as to have a compounding ratio of 1: 4 by a conventional method. While cooling with a mirror-surface cooling drum, an unstretched film was obtained. This unstretched film is heated at a temperature of 1
After stretching 2.9 times in the longitudinal direction at 20 ° C and cooling to 40 ° C,
After stretching 2.8 times in the width direction at a temperature of 115 ° C, 200 ° C
In the vertical and horizontal directions, heat treatment was performed for 3% each for 5 seconds, followed by slow cooling at 150 ° C./120° C. for 2 seconds each. Table 1 shows the physical properties of the obtained film and the properties when the film was laminated on a metal plate and made into a can. As can be seen from Table 1, it was found that the moldability, impact resistance and taste characteristics were excellent.

Example 2 Naphthalenedicarboxylic acid copolymerized polypropylene terephthalate (weight of terephthalic acid component: weight of naphthalenedicarboxylic acid = 90: 10) as polyester for layer A.
Propylene glycol: 1,3-propanediol is used. ) To obtain a biaxially stretched film in the same manner as in Example 1 except that the film thickness was changed to 20 μm. Table 1 shows the physical properties of the obtained film and the properties when the film was laminated on a metal plate and made into a can. As can be seen from Table 1, it was found that the moldability, impact resistance and taste characteristics were excellent.

Example 3 A film was obtained in the same manner as in Example 1 except that the composition of the polyester A was changed as shown in Table 1, the heat treatment was performed at 180 ° C. for 3 seconds, and the film was formed without relaxing. Was. Table 1 shows the physical properties of the obtained film and the properties when the film was laminated on a metal plate and made into a can. The resulting film had a high heat shrinkage, and slightly reduced moldability and impact resistance.

Example 4 The composite structure was A / B / A (composite ratio: 1: 10: 1).
A film was obtained in the same manner as in Example 2 except that the polyester in the layer B was polyethylene terephthalate and the film thickness was 15 μm. Table 2 shows the physical properties of the obtained film and the characteristics when the film was laminated on a metal plate and made into a can. The obtained film had particularly good moldability.

Example 5 The composite configuration was B / A / B (composite ratio: 1: 10: 1).
A film was obtained in the same manner as in Example 2 except that the longitudinal stretching temperature was lowered by 10 ° C. and the stretching ratio was set to 3.1 times. Table 2 shows the physical properties of the obtained film and the characteristics when the film was laminated on a metal plate and made into a can. Although the obtained film had slightly deteriorated moldability, it had particularly good taste characteristics and impact resistance.

Example 6 A film was obtained by using only the polyester A of Example 3 in which the particles were changed, lowering the longitudinal stretching temperature by 15 ° C., and increasing the longitudinal and transverse stretching ratios to 3.2 times. Table 2 shows the physical properties of the obtained film and the characteristics when the film was laminated on a metal plate and made into a can. The resulting film had slightly reduced moldability, impact resistance, and taste characteristics.

Comparative Example 1 Example 1 was repeated except that untreated 0.3 mol of colloidal silica-containing 14 mol% isophthalic acid copolymerized polyethylene terephthalate was used, the stretching temperature was 95 ° C., and the stretching ratio was 3.3 times. A biaxially stretched film was obtained in the same manner as described above. As a result, as shown in Table 3, the impact resistance and taste characteristics were significantly reduced.

Comparative Example 2 As polyester A, 10 mol% of isophthalic acid copolymerized polypropylene terephthalate containing 0.2% by weight of aggregated silica having an average particle diameter of 0.8 μm was polymerized. The polymerization is carried out by conducting an esterification reaction using terephthalic acid and 1,3-propanediol as starting materials, and then adding 1,1 to the reaction product.
A slurry in which particles are dispersed in 3-propanediol,
Polycondensation reaction was performed by adding phosphoric acid as a titanium catalyst and a heat-resistant stabilizer to obtain a polyester composition A for layer A.
Polymer physical properties of the polyester composition A were an intrinsic viscosity of 0.65. The obtained polyester is subjected to a longitudinal stretching temperature of 100 ° C., a stretching ratio of 3.0 times, and a transverse stretching temperature of 100 to 15 °.
The film was heat treated at 180 ° C. and rapidly cooled to obtain a biaxially stretched film. As a result, as shown in Table 3, the taste characteristics were significantly reduced.

Comparative Example 3 A biaxially stretched film was produced in the same manner as in Example 1 except that polyethylene terephthalate containing 0.5 μm of calcium carbonate was used as the polyester, the stretching temperature was 95 ° C., and the stretching ratio was 3.3 times. I got As a result, as shown in Table 3, moldability and impact resistance were significantly reduced.

[0048]

[Table 1]

[0049]

[Table 2]

[0050]

[Table 3]

The symbols in the table are as follows.

AA: acetaldehyde (content in polyester (ppm)) EG: ethylene glycol PET: polyethylene terephthalate PET / I: isophthalic acid copolymerized polyethylene terephthalate PG: 1,3-propanediol P (E / P) T: Propylene glycol copolymer PET
(Using 1,3-propanediol) PPT: polypropylene terephthalate (using 1,3-propanediol) PPT / N: naphthalenedicarboxylic acid copolymerized polypropylene terephthalate PPT / I: isophthalic acid copolymerized polypropylene terephthalate PET / N: naphthalenedicarboxylic acid The copolymer PET T: N indicates the weight ratio of the terephthalic acid residue to the naphthalenedicarboxylic acid residue.

[0053]

Industrial Applicability The polyester film for laminating a metal plate of the present invention has not only excellent moldability when forming into a can or the like, but also excellent impact resistance, as well as excellent taste characteristics, particularly, excellent taste characteristics after retort. It can be suitably used for metal cans manufactured by molding.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a metal can.

[Explanation of symbols]

 1: Thin wall 2: Neck

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08K 3/36 C08K 3/36 C08L 67/02 C08L 67/02 // B29C 55/12 B29C 55/12 B29K 67:00 B29L 7 : 00

Claims (11)

[Claims] 1. An acid component comprising at least 96 mol% of terephthalic acid and / or naphthalenedicarboxylic acid, and a glycol component of 0 to 95 mol% of ethylene glycol.
A polyester film for laminating a metal plate, comprising polyester A consisting of 5 to 100 mol% of propylene glycol as a main component. 2. The polyester film for metal plate lamination according to claim 1, wherein the propylene glycol is 1,3-propanediol. 3. The polyester film for metal plate lamination according to claim 1, wherein the weight ratio of terephthalic acid to naphthalenedicarboxylic acid of the polyester A is 60/40 to 95/5. 4. The polyester film according to claim 1, wherein 96% by mole or more of the acid component comprises terephthalic acid and / or naphthalenedicarboxylic acid,
And the glycol component is ethylene glycol 60-100.
A composite polyester film for laminating a metal plate, comprising a polyester film composed mainly of polyester B consisting of 0 mol% and 0 to 40 mol% of propylene glycol. 5. The composite polyester film for metal plate lamination according to claim 4, wherein the composite composition of the polyester in the composite film is a two-layer composite of polyester A / polyester B. 6. The composite polyester film for metal plate lamination according to claim 4, wherein the composite composition of the polyester in the composite film is a three-layer composite of polyester A / polyester B / polyester A. 7. The composite polyester film for metal plate lamination according to claim 4, wherein the composite composition of the polyester in the composite film is a three-layer composite of polyester B / polyester A / polyester B. 8. Polyester A has an average particle size of 0.01
The composite polyester film for metal plate lamination according to any one of claims 1 to 7, wherein the composite polyester film contains 0.01 to 0.5% by weight of particles having a particle size of 5 to 5 µm. 9. The film layer to be laminated on a metal plate has a bulk particle concentration of 50 n from the film surface.
The composite polyester film for metal plate lamination according to any one of claims 1 to 8, wherein the ratio of the surface particle concentration in m is 1/5 or less. 10. The polyester film for laminating a metal plate according to claim 1, wherein the heat shrinkage at the time of treatment at 150 ° C. for 30 minutes is 5% or less. 11. The film layer made of polyester B has a refractive index in the thickness direction of 1.5 or more.
The polyester film for a metal plate laminate according to any one of the above.