JP3316913B2 - Heat-sealable polyester film and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sealable polyester film having a thin film laminated thereon, and more particularly, to a heat-sealable resin film which is laminated on a flexible polyester film.
The present invention relates to a heat-sealable polyester film having excellent flexibility, sealing power, fragrance retention and the like.

[0002]

2. Description of the Related Art Polyethylene terephthalate (PET) biaxially stretched film, which is a representative example of a polyester film, is an industrial material and a magnetic recording material because of its excellent mechanical strength, thermal properties, humidity properties and many other excellent properties. It is used in a wide range of fields such as packaging materials.

[0003] On the other hand, ordinary PET films are poor in flexibility, are easily cleaved in the base layer even if a heat sealing layer is provided, and have poor sealing power.

[0004]

DISCLOSURE OF THE INVENTION The present invention has the flexibility not inherent in PET film as described above,
In particular, it is an object of the present invention to provide a heat-sealable polyester film based on a flexible polyester having good heat-sealability and a method for producing the same.

[0005]

According to the present invention, there is provided a heat-sealable polyester film having a Young's modulus of 1 or less.
0-250 kg / mm ² polyethylene terephthalate
Characterized in that a heat-sealing resin is laminated on at least one surface of a biaxially oriented polyester film composed of a flexible polyester A containing as a main component .

In a flexible polyester film constituting the heat-sealable polyester film of the present invention,
Young's modulus is 10 to 250 kg / mm ² , preferably 50
~200kg / mm ^2, when the Young's modulus is too low, the handling property is poor undesirable because there is no stiffness when the bag. Further, in the present invention, it is necessary that the material is biaxially oriented in view of the change with time of the Young's modulus, the operating temperature range, and the productivity. In addition, the plane orientation coefficient Fn obtained from the refractive indices (Nx, Ny, Nz) in the longitudinal direction, the width direction, and the thickness direction =
The value of (Nx + Ny) / 2-Nz is 0.005 or more, preferably 0.01 or more, particularly preferably 0.02 to 0.1.
A value of 4 is desirable because the workability of the film is good.

In the flexible polyester A mainly comprising the heat-sealable polyester film of the present invention, the dicarboxylic acid component constituting the polyester includes aromatic dicarboxylic acid, alicyclic dicarboxylic acid, aliphatic dicarboxylic acid, and polyfunctional acid. And the like. Aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, diphenic acid, and derivatives thereof, and alicyclic dicarboxylic acids include 1,4-cyclohexanedicarboxylic acid and derivatives thereof. There are, as aliphatic dicarboxylic acids, adipic acid, sebacic acid, dodecanedioic acid, eicoic acid, dimer acid and derivatives thereof, and the like, and polyfunctional acids include trimellitic acid, pyromellitic acid and derivatives thereof. It is typical. As the alcohol component,
Ethylene glycol, 1,4-butanediol, 1,6
-Hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol, 1,4-cyclohexanedimethanol, bisphenol and derivatives thereof are typical. Further, the flexible polyester A used in the present invention is a block of a polyester ether obtained by copolymerizing a polyether such as polyethylene glycol or polytetramethylene glycol, or a polyester amide obtained by copolymerizing a polyamide, or an aliphatic polyester such as polycaprolactone. It also includes a copolymer and the like.

[0008] Among these polyesters, the present invention
The film formability, such as biaxial stretching properties, humidity properties, heat resistance, chemical resistance, low cost and other viewpoint et al, polyethylene terephthalate (PET) as a main component, preferably the acid component and alcohol component of the polyester 50 each
A polyester whose mole% or more is terephthalic acid, ethylene glycol or a derivative thereof is used as the flexible polyester A of the flexible polyester film of the present invention. Further, when the glass transition temperature (Tg) is 50 ° C. or less, flexibility and piercing strength are improved, which is preferable.

Further, in order to impart flexibility to the film, it is effective to copolymerize, for example, an aliphatic dicarboxylic acid, a polyether, or an aliphatic polyester with a polyester mainly composed of PET. Copolymerization of a long-chain aliphatic dicarboxylic acid having 10 or more, preferably 20 or more alkylene groups is preferred in terms of flexibility and quality stability. Examples of the long-chain aliphatic dicarboxylic acid include dodecandioic acid, eicoic acid, dimer acid and derivatives thereof, and in particular, in the present invention, among these, a branched aliphatic dicarboxylic acid having a branched structure may be used. From the viewpoint of improving the impact resistance, it is preferable to use a dimer acid from the viewpoint of improving heat resistance and transparency.

Here, dimer acid is a general term for a mixture of a linear branched structure and a cyclic branched structure obtained by dimerizing and hydrogenating an unsaturated aliphatic dicarboxylic acid such as methyl oleate. Has 20 to 80 carbon atoms,
Preferably it is 30-60. Moreover, although the unsaturated bond usually remains, the bromine value measured by ASTM-D-1159 is 0.05 to 10 (g / 100 g), preferably 0.1 to 5 (g / 100 g). Is heat resistant,
It is preferable because of its excellent flexibility. The copolymerization amount of the dimer acid is from 1 to 40 mol%, preferably from 5 to 20 mol%, based on the acid component.

When the flexible polyester A mainly comprising the flexible polyester film of the present invention is, for example, a copolymer polyester containing PET as a main component and an aliphatic dicarboxylic acid for imparting flexibility, the melting point, the glass The transition point and crystallinity decrease, and in the biaxially stretched film manufacturing process, sticking to the cooling drum, sticking to the stretching roll, and sticking to the clips in the tenter during extrusion casting are likely to occur, resulting in reduced productivity. May be. Further, when the copolymerization increases, the biaxial stretching property of the polyester A alone deteriorates, and there is no one-to-one correspondence between the stretching and the stress, resulting in so-called necking stretching, which leads to deterioration of thickness unevenness. Become. This poor biaxial stretching property is particularly attributable to polybutylene terephthalate (PBT).
This is particularly remarkable in a flexible polyester containing as a main component, for example, it is very difficult to obtain a smooth biaxially stretched film using a copolymerized PBT obtained by copolymerizing 15 mol% of dimer acid.

[0012] In view of the above, flexible polyester A
Laminating polyester B having a glass transition point of 45 ° C. or higher, preferably 55 ° C. or higher on at least one surface of the polyester resin in order to prevent sticking to rolls and clips in light of the preferable stretching temperature of polyester A Is preferred.

Regarding the polyester B, a crystalline polyester represented by PET is preferred from the viewpoint of preventing sticking.
Further, it is preferable that the melting point and the glass transition point are higher than those of the polyester A because the thermal dimensional stability of the whole film is improved. Furthermore, after biaxial stretching, polyester A
It is preferable to select a polyester having a higher breaking strength and a higher Young's modulus because the breaking strength and the like can be improved while keeping the stiffness of the film soft. Therefore, the lamination of polyester B not only improves the film forming properties, but also has the effect of compensating for the disadvantages of flexible polyester A, such as thermal stability and strength in the tensile direction, as well as improving the slipperiness. The effect of improving the quality can be provided.

The dicarboxylic acid component, alcohol component, and copolymerization components such as polyether, polyamide and aliphatic polyester constituting polyester B are the same as polyester A. In addition to the glass transition point, polyester B further includes: In order to assist the stretching properties of the flexible polyester A having poor biaxial stretching properties, it is preferable that the polyester be a polyester having good stretching properties. Specifically, a polyester mainly composed of PET, a polyester mainly composed of a polymer composed of 1,4-cyclohexanedimethanol and terephthalic acid, and the like are preferable. PET, copolymerized PET with isophthalic acid, adipic acid, sebacin 4-8 carbon atoms such as acids
And copolymerized PET with an aliphatic dicarboxylic acid having an alkylene group. In the case of a copolymer, the amount of the copolymer component is 1 to 40 mol%, preferably 5 to 20 mol%.

As the polyester B, polyethylene terephthalate, isophthalic acid copolymerized PET, copolymerized with an aliphatic dicarboxylic acid having an alkylene group having 4 to 8 carbon atoms such as adipic acid and sebacic acid, etc. It is preferable from the viewpoint of raw material recovery. Further, by reducing the thickness of the polyester B layer, it is possible to make the raw material of the layer B recoverable for the polyester obtained by copolymerizing a long-chain aliphatic dicarboxylic acid as the polyester A. As the polyester A or B, a polymer obtained by blending two or more kinds of polyesters may be used.

The polyester B is laminated on at least one side of the flexible polyester A, and the thickness ratio thereof is 1 in the ratio of the total thickness of the polyester A layer to the total thickness of the polyester B layer. : 1 to 50: 1, preferably 2: 1 to 25: 1 (total of A layer: total of B layer). B
If the proportion of the layer is too small, the effect of improving the biaxial stretchability is unfavorably reduced, and if the proportion of the B layer is large, the flexibility and piercing characteristics of the film are undesirably impaired.

When the polyester B is laminated on both sides of the flexible polyester A, the polyester B may have a slightly different composition or the like from each other within the scope of the present invention. In order to improve the adhesion between the layers in the laminated film, for example, flexible polyester A is used as 2
B using a variety of polymers A1, A2 and polyester B
Five layers such as / A1 / A2 / A1 / B may be laminated, or B / (A1 + A) by mixing two kinds of polymers A1 and A2.
2) It may be like / B. Further, the puncture strength defined below is 10 kg / mm or more, preferably 15 kg / mm.
mm or more, more preferably 20 kg / mm or more, for example, when the film is heat-sealed into a bag, the durability of the bag is improved, and therefore it is desirable. Here, the piercing strength means that a film is stretched on a ring having a diameter of 40 mm without loosening, and a sapphire needle having a tip angle of 60 degrees and a tip R of 0.1 mm is used to pierce the center of the circle at a speed of 50 mm / min. , The force when the needle penetrates is converted to a film thickness of 1 mm. The size of the tip R is 0.5 m
m and the piercing strength is 50 kg / mm or more,
This is preferable since the solid material has excellent durability against other contact substances after bagging.

In the present invention, B comprising polyester B
The addition of inert particles to the layer is effective in improving slipperiness. Here, examples of the inert particles include inorganic compounds such as silicon oxide, aluminum oxide, zirconium oxide, calcium carbonate, and magnesium carbonate, and insoluble organic compounds such as crosslinked polystyrene, crosslinked divinylbenzene, benzoguanamine, and silicone. In particular, colloidal silica, pulverized silica, crosslinked polystyrene, silicone and the like are preferable in terms of transparency. The average particle diameter is preferably from 0.01 to 10 μm, and more preferably from 0.
1 to 8 μm. The addition amount is 0.001 to 10% by weight, preferably 0.01 to 5% by weight. Note that the polyester A and / or the heat-sealable polyester may also contain the above-described particle type added to the polyester B.

In the flexible polyester film of the present invention, additives such as an antistatic agent, a heat stabilizer, an antioxidant, a crystal nucleating agent, a weathering agent, an ultraviolet absorber, a pigment and a dye impair the object of the present invention. Can be used to a lesser extent.
In addition, surface irregularities such as embossing and sand matting, or surface treatments such as corona discharge treatment, plasma treatment, and alkali treatment may be performed as necessary. Further, the flexible polyester film of the present invention may have an easy-adhesion treatment agent, an antistatic agent, a water vapor / gas barrier agent (such as polyvinylidene chloride), a release agent, an adhesive, an adhesive, a flame retardant, an ultraviolet absorber, and a matting agent. May be coated or printed with pigments, dyes, etc., and vacuum-deposited metals such as aluminum, aluminum oxide, silicon oxide, palladium and their compounds for the purpose of shading, water vapor / gas barrier, surface conductivity, infrared reflection, etc. The purpose and method are not limited to the above.

The thickness of the heat-sealable polyester film of the present invention is not particularly limited, but is effectively used at 1 to 1000 μm, preferably 5 to 500 μm.

The heat-sealable polyester film of the present invention is obtained by laminating a heat-seal resin on at least one surface of the above-mentioned flexible polyester film. The heat sealing resin preferably has a thermal bonding initiation temperature of 80 ° C. or more and 180 ° C. or less. The relationship between the melting point of the heat sealing resin and the melting point of the flexible polyester film (biaxially oriented polyester film) is as follows.
The difference between the melting point of the biaxially oriented polyester film and the melting point of the heat sealing resin is preferably 20 ° C. or higher (the biaxially oriented polyester film is higher). Also,
The melting point of the heat seal resin is preferably 200 ° C. or less. Preferred heat seal resins include, for example, copolymerized polyesters such as those obtained by copolymerizing isophthalic acid component with polybutylene terephthalate and those obtained by copolymerizing isophthalic acid component with polyethylene terephthalate. There is no particular limitation as long as the resin has good adhesiveness. Lamination method of heat seal resin, lamination method, coating method,
A known method such as a coextrusion method can be used.

The laminated resin layer is formed, for example, by laminating a polyester resin and a heat seal resin by a co-extrusion method.
It is formed by performing a heat treatment after the axial stretching. Then, by setting the heat treatment temperature to be equal to or higher than the melting point of the heat seal resin and equal to or lower than the melting point of the polyester resin, a heat seal resin layer having the above-described characteristics is formed. The thickness of the heat seal resin layer is 0.01 to 20 μm, preferably 0.1 to 20 μm.
〜１０10 μm.

In the present invention, since the core layer of the biaxially oriented polyester film is a flexible polyester film, the sealing force is improved, and the shortage of the sealing force due to cleavage of the ordinary PET film is eliminated.

Further, in the heat-sealable polyester film, if the Young's modulus at 100 ° C. of the biaxially oriented polyester film is 20 kg / mm ² or more and the heat shrinkage is 5% or less, wrinkles on a cooling can are obtained. This is preferable because the generation of slag can be effectively prevented.

When the biaxially oriented polyester film has a Young's modulus at room temperature of 50 kg / mm ² or more, the dropping strength and the rubbing resistance can be further improved, and the prevention of heat loss on the can is also achieved. it can.

Next, the method for producing the heat-sealable polyester film of the present invention will be described, but the present invention is not limited thereto. Polyester A, polyester B and heat seal resin (hereinafter sometimes referred to as polymer C)
Is melt-extruded by a separate extruder, and two or three or more types of polymers are converted to C / A / C, B / A / C, B /
Composite extrusion in the form of a sheet with A / B / C or the like, and quenched casting. The resulting cast sheet is produced by a usual sequential biaxial stretching film forming process in which longitudinal stretching, transverse stretching, and heat treatment are performed. In addition, a simultaneous biaxial stretching process, a tubular process, or the like can also be employed. In order to improve the adhesiveness between layers in a laminated film of polyester A and polyester B, for example, two kinds of polymers A1 and A are used as flexible polyester A.
2, and B / A1 / A2 / A1 using polyester B
/ B or two types of polymer A
1, A2 may be mixed to give B / (A1 + A2) / B.

In the above-described sequential biaxial stretching process, simultaneous biaxial stretching process, and the like, in order to achieve the physical properties of the flexible polyester film of the present invention, the stretching temperature and the heat treatment temperature are important. As a result of repeated experiments, when the Tg of polyester A is lower than 50 ° C., particularly, the stretching temperature is Tg of polyester A + 10 ° C. to 130 ° C., preferably Tg + 20 ° C. to 120 ° C., more preferably Tg
When the temperature is + 30 ° C. or more and 110 ° C. or less, film-forming properties and flexibility are improved, and piercing strength is improved. Heat treatment temperature is 170-2
When the temperature is 35 ° C., flexibility and dimensional stability are excellent, and piercing strength is improved. The heat treatment temperature of the present invention means a temperature of a melting peak of a metacrystal associated with thermal crystallization remaining as a heat history during heat treatment of polyester, which is observed using a differential scanning calorimeter, and is not necessarily a manufacturing temperature. It does not correspond to the heat treatment roll in the film or the ambient temperature in the oven.

On at least one side of the biaxially oriented flexible polyester film obtained as described above, a heat seal resin having a thermal bonding initiation temperature of 80 ° C. or more and 180 ° C. or less is laminated. The lamination method is not particularly limited, and a known method can be employed. However, it is preferable to laminate the polyester resin and the heat seal resin by a co-extrusion method.

The thin film laminated flexible polyester film of the present invention is conventionally suitably used for flexible packaging, and is particularly suitable for applications requiring heat sealability. In particular, when applied to packaging materials, a material excellent in processability, particularly heat sealability, can be obtained, and excellent characteristics that cannot be obtained with a normal PET film can be obtained.

[Measurement and evaluation methods of physical properties and properties]
Methods for measuring and evaluating various physical properties and characteristics used in the description of the present invention or the examples described later will be described. (1) Melting point (Tm), glass transition temperature (Tg) Measured using a differential scanning calorimeter DSC (manufactured by PerkinElmer). Sump 10 mg under nitrogen flow 280
C. for 5 minutes, and then quenched with liquid nitrogen. In the process of raising the temperature of the obtained sample at a rate of 10 ° C./min, a specific heat change based on a transition from a glassy state to a rubbery state is read, and this temperature is defined as a glass transition temperature (Tg). The melting point (Tm) was used.

(2) Mechanical properties The tensile Young's modulus, breaking strength, and breaking elongation are AS
It measured according to TM-D-882-81 (method A). The Young's modulus at 100 ° C. was measured by a dynamic viscoelasticity measuring device (Rheoviblon II type). Note that the heat-sealing tree
The resin is heat-sealable by successive biaxial stretching after compound extrusion.
When obtaining a stell film, from flexible polyester A
Or at least one side of flexible polyester A
Biaxially Oriented Polyester Laminated with Polyester B
The mechanical properties of the film are flexible except for the heat-sealing resin.
Soft polyester A alone or flexible polyester
A and polyester B
Lum was measured and determined.

(3) Thermal Shrinkage A film sample having a test length of 200 mm and a width of 10 mm was heat-treated in a hot-air oven without applying a load, and the amount of shrinkage was measured to obtain a ratio to the test length.

(4) Puncture Strength A film having a diameter of 40 mm is stretched so as not to be slackened.
Using a 0.1mm sapphire needle, the center of the circle is 50m
The needle was pierced at a speed of m / min, and the force when the needle penetrated was converted to a film thickness of 1 mm, which was defined as the piercing strength. Furthermore, the tip R
The piercing strength when the size of was set to 0.5 mm was also measured and shown as a value in parentheses in the table.

(5) Heat Seal Strength Heat seal with an impulse sealer (Fuji impulse sealer 130 type) and bond strength per 1 cm width (kg / c)
m) was determined.

[0035]

The present invention will be described below by way of examples. Example 1 Copolyester A having a limiting viscosity of 0.75 by a known method using 85 mol% of terephthalic acid as a dicarboxylic acid component, 15 mol% of hydrogenated dimer acid having 36 carbon atoms, and 100 mol% of ethylene glycol as a diol component. (Tm22
2 ° C., Tg 17 ° C.). On the other hand, 90 mol% of terephthalic acid and 10 mol% of sebacic acid as dicarboxylic acid components,
Copolymer Polyester B (Tm 233 ° C., Tg 55 ° C.) having an intrinsic viscosity of 0.80 was obtained by a known method using ethylene glycol 100 mol% as a diol component. Further, as a heat seal resin, polybutylene terephthalate (PBT /
I, Tm 165 ° C). The copolymer polyester B contained 0.1% by weight of silicon oxide having an average particle size of 2 μm,
Kaolin having an average particle size of 3 μm is contained in the heat seal resin.
The particles were added by a twin-screw extruder so that the content became 05% by weight.

After drying these three types of copolymerized polyester with a known vacuum dryer, polyester A is supplied to a 90 mmφ extruder, polyester B is supplied to a 40 mmφ extruder, and copolymerized PBT is supplied to a 40 mmφ extruder. Polyester A is 260 ° C, Polyester B is 270 ° C, PBT /
I was melt-extruded at 200 ° C., laminated into three layers such as polyester B / polyester A / (PBT / I) (lamination thickness ratio 1: 20: 3), and then expanded in the width direction in the die.
It was discharged in a sheet form from a slit of mm. While applying a positive charge to the sheet, it was tightly cooled and solidified on a casting drum kept at 25 ° C, then stretched longitudinally 3.3 times at 70 ° C with a stretching roll, and 3.3 times transversely at 80 ° C in a tenter. Stretching, heat treatment at 210 ° C. for 5 seconds (heat treatment temperature 198
° C) to obtain a biaxially stretched flexible polyester film having a thickness of 15 µm. The obtained film had good slipperiness and good roll appearance.

When the heat-sealing resin surfaces of the obtained film were overlapped with each other and heat-sealed with an impulse sealer, a very large seal strength of 2.3 (kg / cm) was obtained.

Example 2 The amount of dimer acid copolymerized in polyester A was 10 mol% (terephthalic acid 90 mol%) (Tm 234 ° C., Tg 33 ° C.)
0.05% by weight of silicon oxide particles having an average particle size of 2 μm
A PBT / I (isophthalic acid component: 35 mol%) containing 0.05% by weight of silicon oxide particles having an average particle diameter of 2 μm was used as a heat seal resin, and the lamination thickness ratio was 1: 1.
A flexible polyester film having a thickness of 20 μm was obtained in the same manner as in Example 1 except that A / C was laminated. The sealing strength of the obtained film with an impulse sealer was 2.1 (kg / cm), a good value.

Example 3 The amount of dimer acid copolymerized in polyester A was 10 mol% (terephthalic acid 90 mol%) (Tm 234 ° C., Tg 33 ° C.)
0.1% by weight of silicon oxide particles having an average particle size of 2 μm, and 0.05% by weight of silicon oxide particles having an average particle size of 2 μm as a heat sealing resin.
Flexible polyester having a thickness of 20 μm in the same manner as in Example 1 except that the laminated thickness ratio is 1: 1 (laminated structure C / A / C) using ET (isophthalic acid component 25 mol%, Tm 195 ° C.). I got a film. When the seal strength of the obtained film was tested by an impulse sealer, the seal strength showed a good value of 1.8 (kg / cm).

Comparative Example 1 As polyester A, PET (Tm 255 ° C., Tg 70
C.), and a film was formed under the same conditions as in Example 2 to obtain a heat-sealable film having a thickness of 20 μm. The sealing strength of the obtained film with an impulse sealer is 0.1.
6 (kg / cm), which is smaller than that of Example 2 because cleavage occurred near the interface between the PET layer and the PBT / I layer because the plane orientation of PET as the base layer advanced. Conceivable.

Comparative Example 2 As polyester A, PET (Tm 255 ° C., Tg 70
C.), and a 20 μm heat-sealable film was obtained under the same conditions as in Example 3. The seal strength of the obtained film with an impulse sealer was as small as 1.0 (kg / cm).

[0042]

[Table 1]

[0043]

As described above, according to the heat-sealable polyester film of the present invention, at least one surface of the biaxially oriented polyester film having a Young's modulus of 10 to 250 kg / mm ² and excellent flexibility is heat-sealed. Since the resin is laminated, a film having excellent flexibility and heat sealability can be obtained. In particular, a film suitable for use as a packaging material that requires sealing force and fragrance retention can be obtained.

Continuation of the front page (56) References JP-A-2-219832 (JP, A) JP-A-52-151365 (JP, A) JP-A-56-166065 (JP, A) JP-A-3-47775 (JP, A) JP-A-55-166248 (JP, A) JP-A-5-131601 (JP, A) JP-A-3-231929 (JP, A) JP-A-6-79776 (JP, A) 6-190969 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 1/00-35/00

Claims (7)

(57) [Claims] 1. A flexibility mainly composed of polyethylene terephthalate having a Young's modulus of 10 to 250 kg / mm ^2.
A heat-sealing polyester film comprising a heat-sealing resin laminated on at least one surface of a biaxially oriented polyester film made of polyester A. 2. The heat-sealable polyester film according to claim 1, wherein a difference between a melting point of the biaxially oriented polyester film and a melting point of the heat seal resin is 20 ° C. or more. 3. The heat-sealing resin has a melting point of 200 ° C.
The heat-sealable polyester film according to claim 1, wherein: 4. The flexible polyester A has 10 carbon atoms.
Long-chain aliphatic dicarboxylic acid having the above alkylene group
The heat-sealable polyester film according to any one of claims 1 to 3, which contains 1 to 40 mol% . 5. The polyester film according to claim 1, wherein
Glass transition on at least one side of flexible polyester A
Claims: Polyester B having a temperature of 45 ° C or higher is laminated.
6. The heat-sealable polyester film according to any one of 1 to 5 . 6. The polyester B is polyethylene
The heat-sealable polyester film according to claim 5 , comprising phthalate as a main component . 7. The heat-sealing poly according to claim 1, wherein
Ester film is heat-sealed with polyester resin
Laminate resin by co-extrusion method, heat-treat after biaxial stretching
In the manufacturing method, the heat treatment temperature is reduced.
Above the melting point of the heat seal resin and below the melting point of the polyester resin
Heat-sealable polyester foil characterized by the following:
The manufacturing method of Irum.