JP3221531B2 - Polyester composite film for metal lamination - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester composite film for laminating a metal, and more particularly to a metal can having a long can wall (for example, a beer can, a carbonated beverage can, a juice can, an aerosol can, etc.). The present invention relates to a polyester composite film suitable as a constituent material of a laminated steel sheet.

[0002]

2. Description of the Related Art Conventionally, a metal can is coated to prevent a metal odor from migrating to its contents and preventing the contents from corroding the inner surface of the metal can.
For the purpose of simplifying the process, improving hygiene, preventing pollution, etc., after laminating the polyester film by heating and pressure bonding to a metal plate such as tin, tin-free steel, aluminum, etc. without using an organic solvent, Investigation of a method for making cans by drawing or the like is in progress.

For example, JP-B-57-23584, JP-B-59-34580, and JP-B-62-61.
No. 427 discloses the technical contents thereof. However, in this technique, when laminated with a steel plate at a temperature equal to or higher than the melting point of the polymer constituting the film and sufficiently adhered to the steel plate, an impact during can making, that is, a local impact on the bottom of the can due to an impact applied to the stopper at a high speed. Film tears (cracks) occur. In order to avoid such drawbacks, when trying to improve the flexibility of the film to secure deformation resistance and impact resistance, the film sticks to the punch due to the heat generated by the processing by the die and punch in the can making process. Often, the film on the can wall is torn and torn. further,
Traces of the transfer pins are likely to be formed during transfer in a heat treatment step or the like after the can making process. That is, various problems due to insufficient heat resistance occur. Further, the polyester having improved flexibility has a disadvantage that the property of adsorbing the fragrance component in the can filling is deteriorated, that is, the flavor resistance is poor. From the above, it is not satisfactory as a metal can inner protective layer.

In order to avoid such a disadvantage, Japanese Patent Laid-Open Publication No.
No. 1630 discloses a method using two types and two layers of a composite polyester film. However, it has been difficult to achieve a balance between moldability and heat resistance to a level that satisfies market requirements.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above circumstances, and has a deformability, an impact resistance and an adhesion during a can-making process, and has excellent heat resistance. There is no punch adhesion and no trace of transfer pins during processing.
Provided is a polyester composite film for metal lamination having good flavor resistance.

[0006]

According to the present invention, there are provided an A layer, a B layer,
A polyester composite film composed of a C layer, wherein the A layer is made of polyethylene terephthalate or a copolymer of polyethylene terephthalate and isophthalate having a melting point of 210 ° C. or more, and the B layer is 50 mol% or more of all dicarboxylic acid components. Are terephthalic acid residues, 5 to 50 mol% contain aliphatic dicarboxylic acid residues having 10 or more carbon atoms, 11 to 89 mol% or more of all alcohol components are ethylene glycol residues, and 89 to 11 mol% are 1 to 1 mol%. A polyester composite film for metal lamination, characterized by comprising a polyester resin having a glass transition point of 40 ° C. or lower and consisting of 1,4-butanediol residues, and a C layer comprising a polyester resin having a melting point of 180 to 230 ° C.

The polyester resin constituting the layer A in the present invention must be polyethylene terephthalate or a copolymer of polyethylene terephthalate having a melting point of 210 ° C. or higher and isophthalate. There is no problem that such a polyester resin contains a diethylene glycol residue by-produced in the production process. In addition, other copolymer components may be contained in an amount of 5 mol% or less within the above melting point range, but it is better not to include other copolymer components from the viewpoint of flavor resistance. From the viewpoint of flavor resistance, the content of the diethylene glycol residue is preferably as small as possible.

[0008] The polyester resin must have a melting point of 210 ° C or higher. 220 ° C. or higher is preferred. 210
If the temperature is lower than ℃, the heat resistance is low and punch sticking occurs during the can-making process, the operability of the can-making process is lowered, and the film of the can wall portion is torn, which causes problems such as tearing. Absent. The polyester resin may be polyethylene terephthalate, but a copolymer of polyethylene terephthalate and isophthalate having a melting point of 220 to 250 ° C. is particularly preferable from the viewpoint of deformability and impact resistance. The copolymerization ratio of isophthalate varies depending on the amount of diethylene glycol residue by-produced in the polyester production process, but is generally in the range of 3 to 15 mol%. A layer thickness is 1-20
μm is preferable, and 2 to 15 μm is more preferable. If it is less than 1 μm, the effect of improving heat resistance and flavor resistance is not sufficient, which is not preferable. Conversely, if it exceeds 20 μm, the effect of improving heat resistance and flavor resistance is saturated, and at the same time, deformability and impact resistance are undesirably reduced.

In the polyester resin constituting the layer B in the present invention, 50 mol% or more of the total acid component contains terephthalic acid residues, and 5 to 50 mol% contains aliphatic dicarboxylic acid residues having 10 or more carbon atoms. 11 to 89 mol% of all alcohol components are ethylene glycol residues, and 89 to 11 mol% are 1,
The glass transition point composed of 4-butanediol residues must be 40 ° C. or lower. If the amount of terephthalic acid is less than 50 mol%, heat resistance is insufficient, so that it is not preferable. Carbon number 10
Examples of the above aliphatic dicarboxylic acids include sebacic acid, eicoic acid, dodecanedicarboxylic acid, dimer acid and the like. Dimer acid is obtained by a dimerization reaction of a higher unsaturated fatty acid such as oleic acid and generally has an unsaturated bond in the molecule. Hydrogenation is more preferable because heat resistance and flexibility are improved. In the course of the dimerization reaction, a linear branched structure, an alicyclic structure, and an aromatic nucleus structure are generated, but these structures and amounts are not particularly limited. Aliphatic dicarboxylic acid residues having less than 10 carbon atoms are not preferred because they do not provide sufficient deformability and impact resistance. The content of the aliphatic dicarboxylic acid residue needs to be 5 to 50 mol% based on the total acid component. If it is less than 5 mol%, it is not preferable because imparting of deformability and impact resistance becomes insufficient. Conversely, if it exceeds 50 mol%, the deformability and the impact resistance are saturated, and the heat resistance is undesirably reduced.

[0010] The polyester resin constituting the layer B is not particularly limited to include dicarboxylic acid residues other than terephthalic acid and an aliphatic dicarboxylic acid having 10 or more carbon atoms as an acid component as long as the above range is satisfied. In addition, carbon number 1
The aliphatic dicarboxylic acid residue of 0 or more may be one kind,
Two or more kinds may be used in combination. In the polyester resin, it is necessary that 11 to 89 mol% of all alcohol components are ethylene glycol residues and 89 to 11 mol% are 1,4 butanediol residues. Within this range, the balance between handleability of the resin of the polyester resin and cost is good. When the amount of ethylene glycol residues is larger than the above range, the crystallinity of the resin is lowered, and the handleability is deteriorated. Conversely, if the amount of 1,4 butanedioher residues exceeds the above range, the cost increases, which is not preferable. In addition, it is permissible to contain an alcohol component containing an ether group such as diethylene glycol and an amount produced as a by-product in the polyester production process. In addition, other glycol residues such as propylene glycol, neopentyl glycol, and cyclohexane dimethanol may be contained as long as the content is 5 mol% or less.

The polyester resin constituting the layer B must have a glass transition point of 40 ° C. or less. 30 ° C. or lower is more preferable. When the glass transition point exceeds 40 ° C,
It is not preferable because deformation and impact resistance are not sufficiently imparted. The configuration of the polyester resin constituting the layer B can be arbitrarily set within the above range. Said B
The layer thickness is preferably from 3 to 60 μm. 5 to 40 μm is more preferred. If it is less than 3 μm, it is not preferable because deformation and impact resistance are not sufficiently imparted. Conversely, if the thickness exceeds 60 μm, the imparting of deformability and impact resistance is saturated, and the heat resistance is undesirably reduced. It is also disadvantageous in terms of cost.

The melting point of the polyester resin constituting the layer C must be 180 to 230 ° C. Melting point 230 ° C
If the ratio exceeds the above range, the adhesiveness during heat lamination with a metal plate is reduced, and the film is likely to be broken (cracked) from the starting point of local film peeling at the can wall during can making. Conversely, when the temperature is lower than 180 ° C., the adhesiveness is improved, but the heat resistance is lowered, and wrinkles are apt to be formed during the heat treatment after the can-making process, so that the commercial value as the metal can inner surface protective layer is not preferable.

The structure of the polyester resin is not limited as long as it is within the above-mentioned melting point range, but copolymerized polyethylene terephthalate is preferred in view of cost. The copolymer component may be an acid component or an alcohol component. As the acid component, aromatic dicarboxylic acids such as isophthalic acid, phthalic acid and naphthalenedicarboxylic acid, adipic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, aliphatic dicarboxylic acids such as dimer acid, and cyclohexanedicarboxylic acid And the like. Examples of the alcohol component include propanediol,
Examples thereof include aliphatic diols such as butanediol, hexanediol, and neopentyl glycol; alicyclic diols such as cyclohexanedimethanol; and diols containing an ether bond such as diethylene glycol, triethylene glycol, and polyethylene glycol. These can be used alone or in combination of two or more. The polyester resin is preferably of poor quality from the viewpoint of adhesion. The thickness of the C layer is preferably from 1 to 15 μm. 2 to 10 μm is more preferred. When the thickness is less than 1 μm, the adhesion to the metal plate becomes insufficient, which is not preferable. Conversely, if it exceeds 15 μm, the adhesion to the metal plate is saturated, and the deformability and impact resistance are undesirably reduced.

It is preferable that all of the polyester resins constituting the layers A, B and C have an intrinsic viscosity of 0.5 or more. More than 0.7 is more preferable. Further, the polyester resin constituting each layer may be of one kind or may be used by blending two or more kinds. Further, if necessary, these polyester resins may contain an antioxidant, a heat stabilizer, an ultraviolet absorber, a plasticizer, a pigment, an antistatic agent, a lubricant, a crystal nucleating agent, a lubricant comprising inorganic or organic particles, and the like. The compounding is not restricted at all. The method for producing the above-mentioned polyester resin is not limited at all, and any one produced by either the transesterification method or the direct polymerization method can be used. Also,
It may be produced by a solid phase polymerization method in order to increase the molecular weight. The polyester resin constituting the layer A is a polyester resin having a low oligomer content produced by a vacuum solid-phase polymerization method in that the precipitation of oligomers from the polyester resin during retort treatment or the like after filling the contents in the can is reduced. Is a particularly preferred embodiment.

As described above, the composite film of the present invention
As long as the layer, the layer B, and the layer C are arranged in this order, either an unstretched film or a stretched film may be used. The film having the above constitution is preferably produced by a multilayer extrusion method. Uniaxial stretching and 2 for stretched film
Any of axial stretching may be used, but a biaxially stretched film is preferred from the viewpoint of isotropy. The method for producing the composite film is not limited at all. For example, in the case of a stretched film, any of the T-die method and the tubular method can be applied. When the composite polyester film of the present invention is used for laminating a metal, it is necessary to use the C layer surface as a metal plate side. The bonding method is not particularly limited, but the most preferred embodiment is a method in which the composite polyester film is pressure-bonded to a metal plate heated by an electric current method and thermally bonded.

Hereinafter, the present invention will be described with reference to examples.
The measuring method used in the examples is as follows. (1) Melting point (Tm), glass transition point (Tg) Determined using a differential scanning calorimeter. Sample at 300 ° C
And then quenched with liquid nitrogen for 10 minutes.
Was heated at a heating rate of 10 ° C./min, a specific heat change based on a transition from a glassy state to a rubbery state was read, and this temperature was taken as a glass transition point (Tg). The endothermic peak temperature based on crystal melting was defined as the melting point (Tm).

(2) Adhesiveness A composite polyester film and a tin plate having a thickness of 0.29 mm are overlapped between a metal roll and a rubber roll heated to 230 ° C. (the surface of the C layer of the composite polyester is brought into contact with the tin plate), and pressure is applied. Passed at 20 kg / cm. The adhesive strength (lamination strength) of the film and tin laminate after passing was measured by Tensilon. ：: Laminate strength of 200 g / cm or more ×: Laminate strength of less than 200 g / cm

(3) Stick temperature The temperature of the metal roll heated to a predetermined temperature is brought into contact with the film surface of the laminated film laminated on the tin plate by the method of (2), and the resistance is sharply increased by hand pressing adhesion. Measure. Evaluation was performed at a 5 ° C. pitch, and finally, evaluation was performed at a 1 ° C. pitch to determine the stick temperature. If the stick temperature is less than 80 ° C., the sticking of the punch occurs in the can making process, and the operability of the can is reduced, which is not preferable.

(4) Heat resistance A laminate film laminated on a tin plate by the method of (2) is cut into a piece of 5 cm × 5 cm.
After a weight of 100 g was placed and heated at 200 ° C. for 5 minutes, the appearance of traces of the weight was visually evaluated.

(5) Impact resistance The film surface of the laminated film laminated on a tin plate by the method of (2) is applied with a tip diameter of 4 mm and a weight of 0.4 kg.
Was vertically dropped from a height of 30 cm and deformed to make a model of a can. The can-made model laminated film was 220
After heat treatment at 10 ° C. for 10 minutes, the mixture was placed in a water-laden autoclave and heated at 120 ° C. for 30 minutes to perform a retort model treatment. A weight having a flat bottom and a weight of 0.4 kg was dropped vertically from a height of 24 cm from the tin plate side to a portion deformed by the can-made model of the retort model-processed laminated film to give an impact. A pipe made of polyvinyl chloride was bonded to the film side of the laminated film subjected to the impact with an adhesive, 1% saline was inserted into the pipe, an electrode was inserted, and a voltage of 6 V was applied using a tin plate as an anode, and after 30 seconds, Current value (m
A) was measured. The average value of 10 measurements was displayed.
It is preferably 0.2 mA or less.

(6) Wrinkles after heat treatment A laminate film laminated on a tin plate by the method of (2) was press-formed with a press at a pressure of 100 kg / cm ² to obtain a cup. After the cup was heated at 200 ° C. for 5 minutes, the state of wrinkling of the film was visually evaluated.

(7) Flavor resistance A 10 cm square film is sealed three-sided with an impulse sealer with the layer A side as the inner surface. The three-side sealed bag is filled with 30 cm of d-limonene, and the opening is sealed with an impulse sealer. The sealed bag is allowed to stand in a constant temperature room at 40 ° C. for 10 days to adsorb d-limonene. After the suction bag is opened and d-limonene is discharged, the film of the unsealed portion is cut out to a size of 4 cm square, and d-limonene adheres to the surface.
Wipe clean the limonene in the Kimwipe to measure the weight W ₁ of the film. After vacuum drying the film at 60 ° C. for 24 hours, the weight W ₂ of the film is measured again. d-
The amount of limonene adsorbed was determined by the following equation and expressed as a percentage by weight. The amount of adsorbed d-limonene (%) = W ₁ -W ₂ / W ₂ It is practical that the amount of adsorbed d-limonene is 2% or less.

Example 1 Spherical zeolite 2 having an average particle size of 3 μm as layer A resin 2
Terephthalic acid containing 2,000 ppm by weight of terephthalic acid / isophthalic acid (molar ratio: 95/5) and ethylene glycol (Tm 245 ° C.) [polyester A], and 0.2% by weight of Irganox 1330 as a B-layer resin / Dimer acid having 36 carbon atoms (molar ratio 9
(5/5) and ethylene glycol / 1,4 butanediol (30/70 molar ratio) (Tm
186 ° C., Tg 22 ° C.) [Polyester B] is a resin of C layer and has a spherical zeolite having an average particle diameter of 3 μm and a particle size of 2000 pp
m containing terephthalic acid / isophthalic acid (83/1 molar ratio)
7) and a copolymerized polyester of ethylene glycol (Tm 215 ° C.) [Polyester C] are melted by separate extruders, and the melts are combined in an A / B / C layer order in a die, and then cooled. Extruded and cooled to a total thickness of 32 μm (layer A thickness 12 μm, layer B thickness 15 μm)
m, unstretched film having a C layer thickness of 5 μm). The obtained film and a laminate film with a tin plate (C
Laminate the layer side, the following examples and comparisons are all C
Table 1 shows the characteristics of the laminate surface layer. The composite film obtained in this example is excellent in adhesiveness, operability in can-making, heat resistance, impact resistance, and flavor resistance, and is highly practical as a film for bonding metal. there were.

Comparative Example 1 Copolymerized polyester (Tm) of terephthalic acid / isophthalic acid (molar ratio: 80/20) containing 2,000 ppm of spherical zeolite having an average particle size of 3 μm and ethylene glycol instead of polyester A as the resin for layer A. = 200
° C) The properties of the unstretched film and the laminate film with the tin plate obtained by the same method as in Example 1 except that [Polyester D] was used are shown in Table 1. The composite film obtained in this comparative example had a low stick temperature, was poor in heat resistance, was inferior in operability in can making, and had low practicality as a film for bonding metal.

Comparative Example 2 In place of polyester C as the C layer resin, an average particle size of 3 was used.
Copolymerized polyester from terephthalic acid / isophthalic acid (molar ratio 67/33) containing 2000 ppm of spherical zeolite with ethylene glycol (Tm = 170 ° C.,
(Measured by METTLER's melting point apparatus) [Polyester E]
Table 1 shows the properties of the unstretched film and the laminate film with the tin plate obtained by the same method as in Example 1 except that
Shown in In the composite film obtained in this comparative example, the heat resistance of the adhesive layer was low, wrinkles were generated by heat treatment after lamination, and the film was not practical as a film for bonding metal.

Comparative Example 3 The molar ratio of terephthalic acid / dimer acid in polyester B of the B layer resin was changed from 90/10 to 100/0 (Tm =
195 ° C, Tg50 ° C) [Polyester F]
Table 1 shows the properties of the unstretched film and the laminate film with the tin plate obtained by the same method as in Example 1. The film obtained in this comparative example was inferior in impact resistance, and was of low practicality as a film for metal bonding.

Comparative Example 4 The properties of the unstretched film and the laminate film with the tin plate obtained by the same method as in Example 1 were changed except that the resin of the layer B was changed to the same polyester A as the resin of the layer A instead of the polyester B. It is shown in FIG. The composite film obtained in this comparative example was inferior in impact resistance, and was of low practicality as a film for bonding metal.

Comparative Example 5 The properties of an unstretched film and a laminate film with a tin plate obtained in the same manner as in Example 1 are shown in Table 1, except that polyester C was used in place of polyester C for the C layer resin. The composite film obtained in this comparative example was inferior in adhesiveness and low in practicability as a metal bonding film.

Comparative Example 6 The properties of the unstretched film and the laminate film with the tin plate obtained in the same manner as in Example 1 except that the polyester A was used instead of the resin A in place of the polyester A in Table B are shown in Table 1. Shown in The composite film obtained in this comparative example was inferior in heat resistance and flavor resistance, and was low in practicality as a film for bonding metal.

Example 2 As layer A resin, a copolymerized polyester (Tm 220 ° C.) of terephthalic acid / isophthalic acid (molar ratio 85/15) containing 700 ppm of amorphous silica having an average particle diameter of 2.5 μm and ethylene glycol (Tm 220 ° C.) Polyester G]
Polyester B is melted as a layer resin and polyester D is melted as a C layer resin in separate extruders. The melts are merged in a die in the order of the A / B / C layer, and then extruded onto a cooling drum and cooled. Thus, an unstretched film was obtained.
The unstretched film is first stretched 3.3 times at 85 ° C. in the machine direction and 3.4 times at 100 ° C. in the transverse direction.
Heat setting at 30 ° C., total thickness 30 μm (A layer thickness 9 μm)
m, B layer thickness 18 μm, C layer thickness 3 μm) to obtain a biaxially stretched film. Table 1 shows the properties of the obtained film and the laminate film with the tin plate. The composite film obtained in this example is excellent in adhesiveness, can-making operability, heat resistance, impact resistance, and flavor resistance, and is highly practical as a metal laminating film. Met.

Comparative Example 7 Table 1 shows the properties of a biaxially stretched film and a laminate film with a tin plate obtained in the same manner as in Example 2, except that polyester B was used instead of polyester B as the resin for layer B. The composite film obtained in this comparative example was inferior in impact resistance and was of low practicality as a film for bonding metal.

Comparative Example 8 The properties of a biaxially stretched film and a laminate film with a tin plate obtained by the same method as in Example 2 except that polyester B was used instead of polyester B for the B layer resin are shown in Table 1.
Shown in The composite film obtained in this comparative example was also inferior in impact resistance and was of low practicality as a film for bonding metal.

Comparative Example 9 The properties of a biaxially stretched film and a laminate film with a tin plate obtained in the same manner as in Example 2 except that polyester A was used instead of polyester D for the C-layer resin are shown in Table 1.
Shown in The composite film obtained in this comparative example was inferior in adhesiveness and low in practicability as a film for bonding metal.

Comparative Example 10 Properties of a biaxially stretched film and a laminate film with a tin plate obtained in the same manner as in Example 2, except that polyester D was used as the resin for all the layers A, B and C. Are shown in Table 1. The composite film obtained in this comparative example has a low stick temperature, which is a measure of operability of can making,
Further, the film was inferior in heat resistance and impact resistance and had low practicality as a film for bonding metal.

Comparative Example 11 The properties of a biaxially stretched film and a laminate film with a tin plate obtained in the same manner as in Example 2 except that polyester B was used instead of polyester G as the resin for layer A are shown in Table 1. The composite film obtained in this comparative example was inferior in heat resistance and flavor resistance and was of low practicality as a film for bonding metal.

Example 3 As layer A resin, polyethylene terephthalate (Tm) having an intrinsic viscosity of 1.00 and containing 2,000 ppm of spherical crosslinked polymethylmethacrylic resin beads having an average particle diameter of 3 μm was used.
254 ° C.) as the B-layer resin.
Terephthalic acid containing 0.2% by weight of 0 / timer acid having 36 carbon atoms (molar ratio 90/10) and ethylene glycol /
A copolymer (Tm: 210 ° C., Tg: 10 ° C.) from 1.4 butanediol (molar ratio: 70/30) was prepared by using a polyester C as a resin for the C layer in the same manner as in Example 1 to obtain a total thickness of 32 μA, an A layer of 6 μm, and a B layer. An unstretched film (23 μm, C layer 3 μm) was obtained. Table 1 shows the properties of the obtained film and the laminate film with the tin plate. The composite film obtained in this example was excellent in all the properties and was highly practical as a film for bonding metal.

Example 4 As layer A resin, spherical silica 20 having an average particle size of 3 μm was used.
A copolymer polyester (Tm 225 ° C.) of terephthalic acid / isophthalic acid (molar ratio: 88/12) and ethylene glycol containing 00 ppm was used as a B-layer resin, and terephthalic acid / sebacic acid (molar ratio: 85/15) and ethylene glycol / 1 , 4-butanediol (3/70 molar ratio 70/30)
(Tm200 ° C, Tg22
° C), using polyester D as the resin for the C layer, and in the same manner as in Example 1, a total thickness of 32 µm (A layer 9 µm, B layer 2
An unstretched film (0 μm, C layer 3 μm) was obtained. Table 1 shows the properties of the obtained film and the laminate film with the tin plate. The composite film obtained in this example was excellent in all the properties and was highly practical as a film for bonding metal.

Example 5 Polyester G was used as the resin for layer A, and terephthalic acid / dodecanedicarboxylic acid (molar ratio: 85/1) as resin for layer B.
5) and a copolymerized polyester (Tm19) of ethylene glycol / 1,4-butanediol (molar ratio 20/80)
A biaxially stretched film having a total thickness of 32 μm (9 μm for A layer, 20 μm for B layer, 3 μm for C layer) was obtained in the same manner as in Example 2 using polyester D as the resin for C layer at 5 ° C. and 20 ° C. for Tg. Table 1 shows the properties of the obtained film and the laminate film with the tin plate. The composite film obtained in this example was excellent in all the properties and was highly practical as a film for bonding metal.

[0039]

The polyester composite film for metal lamination of the present invention has a three-layer structure and the properties of the polyester resin constituting each layer are controlled within an appropriate range. When applied to the production of metal cans with a long can wall after joining, they are excellent in heat adhesion to metal plates and in can processing, and have excellent heat resistance. It is very useful because it has good operability in the process and excellent impact resistance and flavor resistance after can making.

[0040]

[Table 1]

──────────────────────────────────────────────────続 き Continuing on the front page (72) Kuniharu Mori 344 Maebata, Kizu, Inuyama-shi, Aichi Prefecture Toyo Boseki, Ltd. Yurika Ashihara Examiner, Headquarters Co., Ltd. (56) References JP-A-5-154971 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 1/00-35/00

Claims (1)

(57) [Claims] 1. A polyester composite film comprising an A layer, a B layer and a C layer, wherein the A layer is made of polyethylene terephthalate having a melting point of 210 ° C. or more or a copolymer of polyethylene terephthalate and isophthalate. The layer contains at least 50 mol% of terephthalic acid residues and at least 5 to 50 mol% of aliphatic dicarboxylic acid residues having 10 or more carbon atoms in all dicarboxylic acid components.
-89 mol% or more is ethylene glycol residue, 89-1
A polyester for metal bonding, wherein 1 mol% is made of a polyester resin having a glass transition point of 1,4 butanediol residue of 40 ° C. or less, and the C layer is made of a polyester resin having a melting point of 180 to 230 ° C. Composite film.