JPH0752351A - Laminated white polyester film for metal laminate - Google Patents

Abstract

PURPOSE:To obtain the excellent laminating properties with a metal, in a biaxially stretched laminated film consisting of two or more layers containing a specific polyester layer A containing a specific amt. of white pigment and a specific polyester layer B which may contain a specific amt. of white pigment, by respectively constituting a surface layer and a metal lamlnating layer of the polyester layers A, B. CONSTITUTION:A polyester layer A has an m.p. of 220-280 deg.C and the content (Wa) of white pigment thereof is set to 5-30wt.%. A polyester layer B has an m.p. of 170-220 deg.C, and the content (Wb) of white pigment thereof is set to 0-10wt.%. In this case, Wb<Wa is necessary. A laminated white polyester film is composed of a biaxially stretched film consisting of two or more layers containing the polyester layers A, B and the thickness of the polyester layer B is set to 1.5-25mum. In this laminated white polyester film, the polyester layer B is laminated to a metal plate as a laminating layer and the polyester layer A is used as a surface layer to which a printing layer is applied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated white polyester film for metal laminating, and more particularly to a metal laminated laminated white polyester film which is excellent in laminating property with a metal and is excellent in hiding power and whiteness. It is a thing.

[0002]

2. Description of the Related Art In recent years, for example, as metal cans for beverages,
By coating the surface of the metal plate on the side that constitutes the inner surface of the can with a thermoplastic resin such as polyester resin, the surface treatment process using a large amount of an organic solvent can be omitted, and
Metal cans are being used that prevent metal elution due to direct contact between the contents and the metal. Then, as a method of printing on the outer cylinder of the metal can, a method of applying a paint containing a white pigment such as titanium oxide to form a white base is adopted.

Recently, a method of laminating a white polyester film containing a white pigment such as titanium oxide has been proposed in place of the above-mentioned base forming method. That is, first, after laminating a white polyester film on the surface of a metal sheet forming a metal can, the white polyester film side is subjected to a can-making process so as to form a can body on the outer surface of the metal can, and then the white polyester film is formed. A method of applying a predetermined print to the surface has been proposed.

[0004]

However, in the case of the conventionally proposed white polyester film,
The adhesive strength between the film and the metal is extremely low, and there is a disadvantage that the laminate film peels off under severe can making conditions such as ironing. The present invention has been made in view of such circumstances, and an object thereof is to provide a metal-laminated laminated white polyester film having excellent laminating properties with a metal, as well as excellent concealing properties and whiteness.

[0005]

That is, the gist of the present invention is to provide a biaxially stretched laminated film having two or more layers including a polyester A layer containing a white pigment and a polyester B layer which may contain a white pigment. The polyester A layer constitutes the surface layer to which the printing layer is applied, the polyester B layer constitutes the metal laminate layer, and the polyester A layer
The layer has a melting point (Tm ^A ) of 220 to 280 ° C., the white pigment content (Wa) is 5 to 30 wt%, and the polyester B layer has a melting point (Tm ^B ) of 170 to 2
20 ° C., and the content (Wb) of the white pigment is 0 to
10% by weight and satisfying the condition of Wb <Wa, and the thickness (t _B ) of the polyester B layer is 1.5 to 25 μm.
m is a laminated white polyester film for metal laminating.

The present invention will be described in detail below. The laminated white polyester film for metal laminating of the present invention comprises a biaxially stretched laminated film having two or more layers including a polyester A layer containing a white pigment and a polyester B layer which may contain a white pigment. The polyester A layer constitutes the surface layer to which the printing layer is applied, and the polyester B layer
The layers make up the metal laminate layer.

First, the polyester A layer will be described. The polyester A layer has a melting point (Tm ^A ) of 220 to 2
It should be 80 ° C, preferably 223 to 260 ° C or less, more preferably 230 to 255 ° C or less. When the melting point (Tm ^A ) of the polyester A layer is less than 220 ° C,
Since it is too soft or inferior in heat resistance, it has the following problems. That is, when performing a can-making process by laminating on the surface of a metal sheet forming a metal can, the mold release property from the mold becomes poor, the film surface is easily scratched after the can making, and printing is difficult. Becomes

The polyester constituting the polyester A layer is a polymer obtained by polycondensing an aromatic dicarboxylic acid and an aliphatic glycol. Aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, naphthalene-
2,6-dicarboxylic acid and the like can be mentioned, and examples of the aliphatic glycol include ethylene glycol, diethylene glycol, tetramethylene glycol, neopentyl glycol, 1,4 cyclohexanedimethanol and the like.

Examples of typical polymers include polyethylene terephthalate (PET), polyethylene-2,6-naphthalene dicarboxylate (PEN), polycyclohexane dimethylene terephthalate (PCT) and the like. The polyester constituting the polyester A layer may be a copolymer as long as the above-mentioned melting point is satisfied.

As the copolymerization component, terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, diphenylsulfodicarboxylic acid, diphenyletherdicarboxylic acid, diphenoxyethanedicarboxylic acid, cyclohexanedicarboxylic acid, which are different from the main component, can be used. Examples thereof include diphenyl dicarboxylic acid, diphenyl thioether dicarboxylic acid, diphenyl ketone dicarboxylic acid, phenylindane dicarboxylic acid, sebacic acid, eicoic acid, dodecane dicarboxylic acid, dimer acid, aromatic dicarboxylic acid having metal sulfonate, and polyether dicarboxylic acid.

On the other hand, the glycol component different from the main component is ethylene glycol, propylene glycol, tetramethylene glycol, cyclohexanedimethanol, 2,2-bis (4-hydroxyethoxyphenyl).
Propane, bis (4-hydroxyphenyl) sulfone,
Examples include diethylene glycol, neopentyl glycol, hydroquinone, cyclohexanediol, polyalkylene glycol and the like.

The copolymerization component may be a multi-component, if desired. The copolymerization amount is preferably 1 to 20 mol%. When the dicarboxylic acid component and the diol component are copolymerized at the same time, the sum of the molar ratio of the copolymerization amount to the total amount of dicarboxylic acid and the molar ratio of the copolymerization amount to the total amount of diol is defined as the above copolymerization amount.

The polyester constituting the polyester A layer may be a blend with another polymer as long as the above-mentioned melting point is satisfied. Other polymers include
For example, polyamide, polyolefin, polycarbonate and the like can be mentioned, and these are blended in a ratio in a range that does not reduce the crystallinity of the polyester constituting the polyester A layer. The proportion of the blend is usually 20% by weight or less, preferably 10% by weight or less, more preferably 5% by weight or less. The glass transition temperature (Tg) of the polyester constituting the polyester A layer is preferably 55 to 80 ° C.

The polyester A layer contains a white pigment, and a general white pigment can be used as the white pigment. Preferred white pigments are titanium oxide, calcium carbonate, barium sulfate and the like, but titanium oxide is particularly preferably used. The average particle size of the white pigment is usually 0.0
It is 5 to 10 μm, preferably 0.1 to 2 μm.

In the polyester A layer, the content (Wa) of the white pigment is 5 to 30% by weight, preferably 8
Must be ~ 20% by weight. When the content (Wa) of the white pigment is less than 5% by weight, sufficient hiding power and whiteness cannot be obtained. In addition to the white pigment, the polyester A layer may contain a color pigment such as magenta, an antiblocking agent such as synthetic silica, and a fluorescent brightening agent.

Next, the polyester B layer will be described. The polyester B layer has a melting point (Tm ^B ) of 170 to 2
It should be 20 ° C, preferably 180-210 ° C. If the melting point (Tm ^B ) of the polyester B layer is less than 170 ° C., it causes sticking to the casting drum or roll during film formation, and blocking occurs between the films. On the other hand, the melting point of the polyester B layer (T
When m ^B ) is higher than 220 ° C., the adhesiveness to the metal deteriorates, and as a result, the film is easily peeled from the metal in the can making process.

As the polyester constituting the polyester B layer, a copolymer selected appropriately from the above-mentioned polyester is used, and in this case, the preferable copolymerization amount is 15 to 50 mol%. The glass transition temperature (Tg) of the polyester constituting the polyester B layer is 5
5-80 degreeC is preferable.

The polyester B layer may contain a white pigment, but the content (Wb) of the white pigment is 10% by weight.
It should be below 5% by weight, preferably below 2% by weight. Since the polyester B layer is required to have adhesiveness to a metal, it is preferable that the amount of white pigment is small as long as the shielding rate of the entire film is allowed.

The shielding rate of the entire laminated white polyester film of the present invention is 0.1 when expressed by optical density (OD).
The range of -0.8, especially 0.1-0.6 is preferable. When the optical density is less than 0.1, the metallic color of the underlying layer affects the surface, and good whiteness cannot be obtained. On the other hand, when the optical density exceeds 0.8, the content of the white pigment is too large, the gloss of the film surface is lowered, and the content of the white pigment in the polyester B layer is inevitably increased. As a result, the lamination strength with metal is reduced.

Therefore, it is necessary that the amount (Wb) of the white pigment contained in the polyester B layer is Wb <Wa with respect to the amount (Wa) of the white pigment contained in the polyester A layer. When a white pigment is contained in the polyester B layer, an antiblocking agent, a fluorescent whitening agent, etc. may be used in combination, if necessary.

The laminated white polyester film of the present invention comprises two or more biaxially stretched laminated films containing the polyester A layer and the polyester B layer as described above. The thickness (t _B ) of the polyester B layer is 1.5 to 25 μm.
must be m. When the thickness (t _B ) of the polyester B layer is less than 1.5 μm, the laminating property with the metal of the film is deteriorated.

The thickness of the polyester B layer (t _B ) and the thickness of the other layers including the polyester A layer (t _A ) are
It is preferable to satisfy the condition of 1.5 ≦ t _B <t _A.
More preferably, the relationship of the layer thickness is 2 ≦ t _B <
t _A , and more preferably 3 ≦ t _B <t _A. t _B ≧
In the case of t _A , it becomes difficult to maintain the laminating property with the metal and satisfy the excellent shielding property. And
Examples of the layer other than the polyester A layer and the B layer include an intermediate layer made of a regenerated polymer.

Next, a can-making process using the laminated white polyester film of the present invention will be described. The type of metal plate used as a can-making material is not limited,
Particularly, a steel plate or an aluminum plate is preferably used. The steel plate may be tin or TFS (Chin Free Steel). The thickness of the metal plate is usually 0.10 to 0.50 m
m, preferably 0.15 to 0.35 mm.

The can-making method includes drawing and redrawing (D /
R processing), drawing and ironing processing (D / I processing), processing used in a talc can (intermediate processing between D / R processing and D / I processing), and the like. The laminated white polyester film of the present invention is particularly preferably used for D / I processed can manufacturing applications. The obtained can has a printed layer on the surface of the polyester A layer and is used as a product.

The obtained cans are mainly used as cans for canned goods and beverages. In particular, it can be suitably used as a can of tea, coffee, cola, juice (tomato, etc.), water whiskey, etc., which has the merit of less elution of metals. It can also be used for the purpose of performing retort treatment for sterilization after filling the contents of a can.

Next, an example of the method for producing the laminated white polyester film of the present invention and the can manufacturing process by D / I processing will be described. As a method for obtaining a laminated film,
Known methods such as a coextrusion method (extrusion-lamination method) and a dry lamination method are used.
The coextrusion method is preferred. Therefore, the film forming method by the coextrusion method will be described below as a representative example.

As the polyester (A) constituting the polyester A layer, a polyester containing a large amount of white pigment and having a low copolymerization ratio is typically used. As the polyester (B) constituting the polyester B layer, a polyester containing no white pigment and having a high copolymerization ratio is typically used. Further, if necessary, a regenerated polymer is used as an intermediate layer between the polyester A layer and the polyester B layer.

First, after drying each of the above polyester chips, the polyester chips are melted at a temperature of 200 to 300 ° C. using separate extruders, merged in a pipe or a die and extruded into a multilayer, and then castig drum. The above is rapidly cooled to obtain an unstretched laminated sheet.

A hopper dryer, a paddle dryer, a vacuum dryer or the like can be used to dry the polyester chips. The T-die method is suitable for extrusion. Further, it is preferable to set the temperature of the castig drum to be low. Further, when casting is performed, a so-called electrostatic adhesion method is used, so that a laminated sheet with less unevenness in thickness can be obtained.

In the subsequent stretching treatment, it is preferable to bring the polyester B layer into contact with a stretching roll because the stretching temperature can be controlled to easily avoid the problem of film sticking. Therefore, from this point of view, it is preferable to select the surface that contacts the castig drum. Usually, the unstretched laminated sheet on the castig drum is turned over and fed to the stretching roll, so that the polyester A layer is brought into contact with the castig drum.

The resulting unstretched laminated sheet has a Tg ^{min of} -10 ° C or higher and a Tc ^{max of} -10 in the subsequent stretching step.
The film is biaxially stretched in the range of 2.0 to 6.0 times in the length and width in the temperature range of ℃ or less. Here, Tg ^min represents the minimum value of Tg of the used raw material polyester, and Tc ^max represents the maximum value of Tc of the used raw material polyester.

The biaxially stretched laminated film has a temperature of not less than the melting point of the polyester (A) and less than the melting point of the polyester (B) and 180 ° C. to 240 ° C. in the subsequent heat setting step.
It is heat set in the temperature range of. The heat setting is generally carried out by tension fixing, but at the time of heat setting and / or cooling after heat setting, the film is relaxed by 20% or less in the longitudinal direction and / or the width direction of the film, or You can also make a tent out.

The thickness of the biaxially stretched laminated film is not particularly limited, but is usually 5 to 75 μm, preferably 10 to 50.
μm, and more preferably 12 to 35 μm.

The laminated white polyester film obtained as described above is laminated with the polyester B layer as a laminate layer on the outer surface of the metal plate on the side forming the can body. Then, a separately prepared transparent polyester film is laminated on the surface of the metal plate which constitutes the inner surface of the can.
For laminating the polyester film on the metal plate, the polyester film is attached to the heated metal plate and then rapidly cooled to bring the metal plate and the polyester film into close contact with each other.

The metal plate laminated with the polyester film is first blank-punched with a cutter and then drawn with a punch to form a cup. Then, the obtained cup is ironed with a redrawing die and an ironing die to be molded into a cup having a predetermined size. Then, it wash | cleans and it prints on a polyester A layer, and it uses it as a drink can.

[0036]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples as long as the above is not exceeded. The film evaluation method is as follows.

(1) Melting point (Tm): Differential calorimeter "SSC580 DSC20 type" manufactured by Seiko Instruments Inc.
10 mg of the sample film was set in a DSC apparatus using the above, the temperature was raised at a rate of 10 ° C./min, and the temperature at the apex of the endothermic peak due to the obtained crystal melting was taken as the melting point.

(2) Shielding Degree: Macbeth Densitometer "TD-9
04 type "was used to measure the transmitted light density under the G filter to determine the degree of shielding. The larger the value of the transmitted light density, the higher the shielding power.

(3) Adhesiveness: A rubber roll is pressure-bonded to a heatable metal roll, and a polyester film and a metal plate (aluminum plate) are overlapped and passed between them, and a laminated product of the film and the metal plate is cross-cut. After cutting, the tape was peeled off to evaluate the adhesive strength. The temperature of the metal roll is 120 ° C, the temperature of the metal plate is 220 ° C, and the roll pressure is 3
kg / cm ² , the passing speed was 10 m / min. Evaluation,
When there was no peeling (◯), when there was peeling (x), and when there was an intermediate between these (Δ), it was divided into three stages.

(4) Formability: The formability was evaluated by the adhesiveness between the above-mentioned DI-processed film and the metal plate aluminum plate. The evaluation is divided into 3 stages: when the film is evenly spread and adheres to the metal plate (○), when the film is unevenly spread (△), and when the film is peeled (x). I went.

Example 1 As polyester A, a copolyester (Tm ^A = 232 ° C.) composed of terephthalic acid / isophthalic acid (molar ratio: 90/10) and ethylene glycol was used, and anatase type titanium oxide having an average particle size of 0.3 μm was used. Polyester containing 13% by weight of was used. As polyester B,
Copolyester consisting of terephthalic acid / isophthalic acid (molar ratio: 79/21) and ethylene glycol (Tm
= 201 ° C) 50 siloids with an average particle size of 1.3 μm
A polyester containing 0 ppm was used.

First, the above polyester chips are dried by a conventional method, and then melted using separate extruders,
After they were combined in a pipe and extruded in multiple layers, they were rapidly cooled on a castig drum to obtain an unstretched laminated sheet. Then
The unstretched laminated sheet was stretched 3.5 times in the machine direction at 83 ° C., then stretched 3.8 times in the transverse direction at 110 ° C., and then 2 times.
Heat treatment was carried out at 10 ° C. for 5 seconds to obtain a laminated polyester film having a thickness of 25 μm (polyester A layer: 22 μm, polyester B layer: 3 μm). The B side of this polyester film was laminated on an aluminum plate to obtain a laminate, and its adhesiveness was evaluated, and D / I processing was performed to evaluate the formability. The results are shown in Table 1.

Example 2 As polyester A, a copolymerized polyester (Tm ^A = 232 ° C.) composed of terephthalic acid / isophthalic acid (molar ratio: 90/10) and ethylene glycol was used, and rutile type titanium oxide having an average particle size of 0.3 μm was used. Polyester containing 13% by weight of was used. As polyester B, a terephthalic acid / isophthalic acid (molar ratio: 75/25) copolymerized polyester composed of ethylene glycol (Tm = 1
Polyester containing 1% by weight of rutile type titanium oxide having an average particle diameter of 0.3 μm at 89 ° C. was used. In the same manner as in Example 1, drying, extrusion, film formation and heat setting were performed to obtain a thickness of 30.
μm (Polyester A layer: 25 μm, Polyester B
A laminated polyester film having a layer of 5 μm was obtained. Using this polyester film, a laminated plate was obtained in the same manner as in Example 1, and the adhesiveness and moldability were evaluated. The results are shown in Table 1.

Comparative Example 1 Polyester terephthalate (Tm = 25) composed of terephthalic acid and ethylene glycol was used as polyester.
500 pp of siloid with an average particle size of 1.3 μm at 7 ° C.
m-containing polyester was used. After drying, extrusion and film formation in the same manner as in Example 1, heat setting was performed at 230 ° C. for 10 seconds to obtain a single-layer polyester film having a thickness of 25 μm. Using this polyester film, a laminated plate was obtained in the same manner as in Example 1, and the adhesiveness and moldability were evaluated. The results are shown in Table 1.

Comparative Example 2 Polyester terephthalate (Tm = 25) composed of terephthalic acid and ethylene glycol was used as polyester.
A polyester containing 12% by weight of anatase type titanium oxide having an average particle size of 0.3 μm was used at 7 ° C.). In the same manner as in Example 1, after drying, extrusion and film formation, 230 ° C
Was heat-set for 10 seconds to obtain a single-layer polyester film having a thickness of 25 μm. Using this polyester film, a laminated plate was obtained in the same manner as in Example 1, and the adhesiveness and moldability were evaluated. The results are shown in Table 1.

Comparative Example 3 As a polyester, polyethylene terephthalate (Tm = 215 ° C.) consisting of terephthalic acid / isophthalic acid (molar ratio: 85/15) and ethylene glycol was added with 500 ppm of siloid having an average particle size of 1.3 μm. Polyester was used. After drying, extrusion and film formation in the same manner as in Example 1, the film was heat set at 180 ° C. for 5 minutes to obtain a single-layer polyester film having a thickness of 25 μm. Using this polyester film, a laminated plate was obtained in the same manner as in Example 1, and the adhesiveness and moldability were evaluated. The results are shown in Table 1.

Comparative Example 4 Polyester terephthalate (Tm = 215 ° C.) consisting of terephthalic acid / isophthalic acid (molar ratio: 85/15) and ethylene glycol was used as polyester, and anatase type titanium oxide having an average particle size of 0.3 μm was used as the polyester 12. A polyester contained in a weight percentage was used. After drying, extrusion and film formation in the same manner as in Example 1, the film was heat set at 180 ° C. for 5 minutes to obtain a single-layer polyester film having a thickness of 25 μm.
Using this polyester film, a laminated plate was obtained in the same manner as in Example 1, and the adhesiveness and moldability were evaluated.
The results are shown in Table 2.

Comparative Example 5 As polyester A, a copolymerized polyester (Tm ^A = 215 ° C.) composed of terephthalic acid / isophthalic acid (molar ratio: 90/10) and ethylene glycol was used, and rutile type titanium oxide having an average particle size of 0.3 μm. Polyester containing 13% by weight of was used. As polyester B, a terephthalic acid / isophthalic acid (molar ratio: 75/25) copolymerized polyester composed of ethylene glycol (Tm = 1
Polyester containing 1% by weight of rutile type titanium oxide having an average particle diameter of 0.3 μm at 89 ° C. was used. In the same manner as in Example 1, drying, extrusion, film formation and heat setting were performed to obtain a thickness of 30.
μm (Polyester A layer: 25 μm, Polyester B
A laminated polyester film having a layer of 5 μm was obtained. Using this polyester film, a laminated plate was obtained in the same manner as in Example 1, and the adhesiveness and moldability were evaluated. The results are shown in Table 2. In this comparative example, the film frequently broke in the heat setting zone.

Comparative Example 6 As polyester A, polyethylene terephthalate (Tm = 2) comprising terephthalic acid and ethylene glycol was used.
A polyester containing 12% by weight of anatase type titanium oxide having an average particle size of 0.3 μm at 57 ° C. was used. Polyester B is polyethylene terephthalate (Tm = 257) composed of terephthalic acid and ethylene glycol.
℃) 500ppm average size 1.3μm of the siloid
The contained polyester was used. Similar to Example 1,
After being dried, extruded, formed into a film and heat-set, the thickness is 25 μm (polyester A layer: 22 μm, polyester B layer: 3 μm
A laminated polyester film of m) was obtained. Using this polyester film, a laminated plate was obtained in the same manner as in Example 1, and the adhesiveness and moldability were evaluated. The results are shown in Table 2.

Comparative Example 7 In Example 1, the thickness of the polyester A layer was set to 24.5.
.mu.m, the thickness of the polyester B layer is 0.5 .mu.m, and the total thickness of the laminated polyester film is changed to 25 .mu.m. The laminated polyester film is dried, extruded, film-formed and heat-set in the same manner as in Example 1. Obtained. Using this polyester film, a laminated plate was obtained in the same manner as in Example 1, and the adhesiveness and moldability were evaluated. The results are shown in Table 2.

Comparative Example 8 In Example 1, as polyester B, terephthalic acid / isophthalic acid (molar ratio: 79/21) and a copolymerized polyester of ethylene glycol (Tm = 201 ° C.)
Anatase type titanium oxide with an average particle size of 0.3 μm
A laminated polyester film having a thickness of 25 μm (polyester A layer: 22 μm, polyester B layer: 3 μm) was obtained by performing drying, extrusion, film formation, and heat setting in the same manner as in Example 1 except that the polyester that was contained by weight% was used. Got Using this polyester film, a laminated plate was obtained in the same manner as in Example 1, and the adhesiveness and moldability were evaluated. The results are shown in Table 2.

[0052]

[Table 1] ──────────────────────────────────── Example Comparative Example 1 2 1 2 3 < Polyester A layer> Tm ^A (° C.) 232 232 257 257 − Pigment content (Wa) (wt%) 13 13 0 12 − <Polyester B layer> Tm ^B (° C.) 201 189 − − 215 Pigment content (Wb) (Wt%) 0 1 − − 0 B layer thickness (t _B ) (μm) 35 − − 25 <Characteristics> Shielding degree (optical density: OD) 0.45 0.50 <0.1 0.42 <0.1 Adhesion ○ ○ × × ○ Moldability ○ ○ × × ○ Overall evaluation ○ ◎ × × × ──────────────────────────────────── ─

[0053]

[Table 2] ──────────────────────────────────── Comparative Example 4 5 6 7 8 <Polyester A ^{layer> Tm A (℃) - 215} 257 232 232 pigment content (Wa) (wt%) - 13 12 13 13 < polyester B ^{layer> Tm B (℃) 215 201} 257 201 232 pigment content (Wb) ( wt%) 120 0 0 13 B layer thickness (t _B ) (μm) 25 3 3 0.5 3 <Characteristics> Shielding degree (optical density: OD) 0.40 0.45 0.42 0.47 0.53 Adhesion △ × ～ △ × × △ Formability △ △ to ○ × ○ △ Overall evaluation △ × to △ × × △ ───────────────────────────────── ────

[0054]

According to the present invention described above, there is provided a metal-laminated laminated white polyester film which is excellent in laminating property with a metal and is also excellent in hiding property and whiteness.

Claims (1)

[Claims] 1. A biaxially stretched laminated film comprising two or more layers including a polyester A layer containing a white pigment and a polyester B layer optionally containing a white pigment, wherein the polyester A layer is provided with a printing layer. The polyester B layer constitutes a metal laminate layer, and the polyester A layer has a melting point (Tm ^A ) of 220 to 280 ° C. and a white pigment content (Wa) of 5 -30% by weight, and the polyester B layer has a melting point (Tm ^B ) of 17
0 to 220 ° C., and content of white pigment (Wb)
Is 0 to 10% by weight, the condition of Wb <Wa is satisfied, and the thickness (t _B ) of the polyester B layer is 1.5 to 2
A laminated white polyester film for metal laminating, which has a thickness of 5 μm.