JPH0848008A - Laminated film and condenser using the same - Google Patents

Abstract

PURPOSE:To obtain a syndiotactic polystyrenic laminated film suitable as a dielectric film for a condenser, excellent in running properties and shaving resistance at the time of the production of the film or a condenser and improved in humidity resistance and self-healing properties at the time of the application of voltage. CONSTITUTION:A laminated film is constituted by forming a surface layer composed of a polyester polymer to at least the single surface of a film composed of a styrenic polymer having a syndiotactic structure and adapted to the production of a condenser.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated film and a capacitor using the same, and more specifically, it is suitable as a dielectric film for a capacitor, and is suitable for running the film at the time of manufacturing the film or the capacitor.
The present invention relates to a syndiotactic polystyrene-based laminated film and a capacitor which have excellent abrasion resistance, and have improved moisture resistance under voltage application and self-healing.

[0002]

2. Description of the Related Art A biaxially stretched film obtained by biaxially stretching and heat-fixing a resin composition containing a syndiotactic polystyrene-based polymer as a main component has excellent heat resistance and electric characteristics and is therefore developed as a dielectric for capacitors. (Japanese Patent Laid-Open No. 2-143851,
JP-A-3-124750 and JP-A-5-200858). Further, a capacitor having improved slipperiness in order to improve running performance and yield during manufacturing is known (JP-A-6-29146 and JP-A-6-29146).
80793).

[0003]

However, in these conventional syndiotactic polystyrene films,
Although abrasion resistance and running property were improved during the production of the film and during the production of the capacitor, the moisture resistance and self-healing property of the obtained capacitor under voltage load were not always satisfactory.

[0004]

The present invention relates to a laminated film characterized in that a surface layer made of a polyester polymer is formed on at least one side of a film made of a styrene polymer having a syndiotactic structure. is there.
Furthermore, the three-dimensional surface roughness SRa of the surface layer is 0.01 (μm) or more, and Sλa (μm) and the glass transition temperature is 4 + 4 × (Tge-Tgc) / Tge ≤ Sλa ≤ 25 + 10 × (Tge- (Tgc)
/ Tge where Tge is the glass transition temperature of polyethylene terephthalate Tgc satisfies the relationship of the glass transition temperature of the surface layer, and the glass transition temperature of the surface layer is Tgc ≥ 50 × (1 + Ae / A) where Ae is The thickness A of the surface layer satisfies the relation of the thickness of the laminated film, the thickness of the surface layer is 30% or less of the thickness of the laminated film, and the dielectric loss tangent (25 ° C, 1kHz) of the laminated film is 0.001 or less. As a result, it is suitable as a dielectric film for capacitors, which prevents slipping of lubricant during film production and capacitor production, has excellent running properties, and has improved moisture resistance under voltage loading and self-healing properties. It is possible to obtain a laminated film for tactic polystyrene. Moreover, a capacitor characterized by using such a syndiotactic polystyrene-based laminated film is excellent in electrical characteristics, and is also excellent in humidity resistance under voltage load and self-healing property.

The polystyrene-based polymer having stereoregular syndiotactic structure used in the present invention has a tacticity in which the side chain phenyl group or substituted phenyl group is quantified by a nuclear magnetic resonance method, which is a diad (constituent unit). 85% or more for 2) and 50 for pentad (5 units)
It is desirable that the structure has a syndiotactic structure of not less than%.

The polystyrene-based polymer includes polystyrene, poly (p-, m- or o-methylstyrene), poly (2,4-, 2,5-, 3,4- or 3,5-dimethylstyrene). ), Poly (alkylstyrene) such as poly (p-tert-butylstyrene), poly (p-, m- or o-chlorostyrene),
Poly (halogenated styrene) such as poly (p-, m- or o-bromostyrene), poly (p-, m- or o-fluorostyrene), poly (o-methyl-p-fluorostyrene), poly ( p-, m- or o-chloromethylstyrene) and other poly (halogen-substituted alkylstyrenes), poly (p-, m- or o-methoxystyrene), poly (p-, m- or o-ethoxystyrene), etc. Poly (alkoxystyrene), poly (p-, m-
Or poly (carboxyalkylstyrene) such as o-carboxymethylstyrene), poly (alkyletherstyrene) such as poly (p-vinylbenzylpropylether), poly (alkylsilylstyrene) such as poly (p-trimethylsilylstyrene), Examples include poly (vinylbenzyldimethoxyphosphide) and the like.

In the present invention, among the polystyrene polymers, polystyrene is particularly preferred. Also,
The polystyrene polymer having a syndiotactic structure used in the present invention is not necessarily a single compound, and if the syndiotacticity is within the above range, a polystyrene polymer having an atactic structure or an isotactic structure is used. It may be a mixture of, a copolymer and a mixture thereof. The polystyrene-based polymer used in the present invention has a weight average molecular weight of 10,000 or more, more preferably 50,000 or more. If the weight average molecular weight is less than 10,000, it is not possible to obtain a film having excellent strength and elongation characteristics and heat resistance. The upper limit of the weight average molecular weight is not particularly limited, but if it is 1500,000 or more, breakage occurs due to an increase in stretching tension, which is not preferable.

Further, the syndiotactic polystyrene film of the present invention can be produced by a known method, for example, a sequential biaxial stretching method in which longitudinal stretching and transverse stretching are carried out in order, as well as transverse / longitudinal stretching.
A stretching method such as a longitudinal stretching method, a longitudinal / transverse / longitudinal stretching method, or a longitudinal / longitudinal / transverse stretching method can be adopted, and the stretching method is selected according to various characteristics such as required strength and dimensional stability. Further, heat setting treatment, vertical relaxation treatment, lateral relaxation treatment, etc. can be performed.

The syndiotactic polystyrene-based polymer used in the present invention may contain, if necessary, a known antioxidant, antistatic agent or the like in an appropriate amount. The blending amount is preferably 10% by weight or less based on 100% by weight of the syndiotactic polystyrene polymer. If it exceeds 10% by weight, breakage easily occurs during stretching, resulting in poor production stability.

As a method for forming the surface layer, the syndiotactic polystyrene polymer and the resin composition for forming the surface are bonded in a melted state inside the die or at the opening of the die, laminated, extruded from the die and rapidly cooled to obtain an amorphous sheet. A method of stretching after producing a syndiotactic polystyrene-based polymer is extruded from a die and rapidly cooled to obtain an amorphous sheet or a uniaxially stretched film. Examples include a method in which individually stretched films are adhered and laminated.

As the polyester resin laminated on the syndiotactic polystyrene of the present invention, a polyester polymer, a polyester copolymer, and a mixture thereof are used, and the dicarboxylic acid component thereof is aromatic. , Aliphatic and alicyclic dicarboxylic acids are used. Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, orthophthalic acid, and 2,6-naphthalenedicarboxylic acid. The amount of these aromatic dicarboxylic acids is preferably 40 mol% or more of the total dicarboxylic acid components, and when it is less than 40 mol%, the mechanical strength and water resistance of the polyester-based resin decrease. Aliphatic and alicyclic dicarboxylic acids include succinic acid, adipic acid,
Sebacic acid, 1,3-cyclopentanedicarboxylic acid, 1,2
-Cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid and the like can be mentioned. The adhesion performance may be improved by adding an aliphatic or alicyclic dicarboxylic acid,
Generally, the mechanical strength and water resistance of the polyester copolymer are lowered.

As the glycol component, an aliphatic glycol having 2 to 8 carbon atoms and an alicyclic glycol having 6 to 12 carbon atoms and a mixture of both of them, ethylene glycol, 1,2-propylene glycol, 1,3 -Propanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, p-
Examples thereof include xylylene glycol. Examples of the aliphatic diol having 4 or more carbon atoms include diethylene glycol and triethylene glycol, and examples of the polyether include polyethylene glycol, polypropylene glycol and polytetramethylene glycol.

The polyester resin is obtained by ordinary melt polycondensation. That is, the above-mentioned dicarboxylic acid component and glycol component are directly reacted to distill off water to esterify, and then a direct esterification method in which polycondensation is performed, or a dimethyl ester of the dicarboxylic acid component and a glycol component are reacted to produce methyl alcohol It is obtained by a transesterification method in which the compound is distilled off to carry out transesterification and then polycondensation. In addition, the polymer can be obtained by a solution polycondensation method or an interfacial polycondensation method. The present invention is not limited to any of the above methods. At the time of melt polycondensation, an antioxidant, a slip agent, inorganic fine particles and an antistatic agent can be added if necessary. The above-mentioned polyether can be added by blending during melt polycondensation or after polymerization.

The laminated film of the present invention comprises a styrene-based polymer film having a syndiotactic structure and a polyester-based surface layer formed on at least one side of the film. By forming the surface layer made of the polyester polymer, the moisture resistance and the self-healing property under the voltage load are improved. In addition, since the polyester resin has relatively good electric properties, the influence of the very good electric properties of the syndiotactic polystyrene polymer on the temperature / frequency dependency is small.

The three-dimensional surface roughness Sλa and
SRa is adjusted by the film forming conditions, the protrusion forming agent, the lamination and the like. The type and amount of the protrusion-forming agent are not particularly limited as long as the three-dimensional surface roughness Sλa, SRa falls within a predetermined range, and examples thereof include metals such as silica, titanium dioxide, talc, kaolinite, and zeolite. Examples include addition of oxides, salts of metals such as calcium carbonate, calcium phosphate and barium sulfate, particles of an organic polymer such as silicone resin and crosslinked polystyrene, and the like. These fine particles may be used alone or in combination of two or more, and the average particle size of the fine particles used is 0.01 μm or more and 2.0 μm or less, particularly 0.05 μm or more and 1.5 μm. The following is preferred, and the degree of variation in particle size (ratio between standard deviation and average particle size) is preferably 25% or less. The addition amount is preferably 0.005% by weight or more and 2.0% by weight or less, and particularly preferably 0.1% by weight or more and 1.0% by weight or less, based on 100% by weight of the syndiotactic polystyrene polymer.

The three-dimensional surface roughness SRa of the surface layer of the syndiotactic polystyrene-based laminated film of the present invention is 0.01 μm.
It is at least m, more preferably at least 0.02 μm. SRa is 0.
If it is smaller than 01, the running property during film production and capacitor production is unfavorable. In addition, the three-dimensional surface roughness Sλa depends on the glass transition temperature of the laminated film, and the optimum range for suppressing slipping off of lubricant during film running and capacitor production, making it an excellent running property, I found it necessary to stay within the range. 4 + 4 x (Tge-Tgc) / Tge ≤ Sλa ≤ 25 + 10 x (Tge-Tgc)
/ Tge Here, Tge is the glass transition temperature of polyethylene terephthalate. Tgc is poor in running property when the glass transition temperature Sλa of the surface layer is less than 4 + 4 × (Tge-Tgc) / Tge. Furthermore, Sλa is 25 + 10 × (Tge−Tg
If it is larger than c) / Tge, white powder is generated due to the scraping of the protrusions, resulting in poor wear resistance, which is not preferable.

In the present invention, the glass transition temperature of the surface layer is influenced by the thickness of the surface layer on the electrostatic capacitance and the dielectric loss tangent temperature / frequency characteristics of the laminated film, and it is necessary to be within the following range. I found out. Tgc ≥ 50 x (1 + Ae / A) where Ae is the thickness of the surface layer A is the thickness of the laminated film If Tgc is less than 50 x (1 + Ae / A), the temperature and frequency characteristics of the capacitor's electrical characteristics become poor. It is not preferable because it increases. In the present invention, the thickness of the surface layer is preferably 30% or less of the thickness of the laminated film. If the thickness is more than 30%, the electrical properties such as capacitance and temperature of dielectric loss tangent, frequency characteristics, and heat resistance become poor, which is not preferable.
The lower limit of the thickness is not particularly limited, but 0.005 μm
If the thickness is thinner, it is difficult to obtain the effect of improving the self-healing property, which is not preferable.

Further, in the present invention, the dielectric loss tangent (25 ° C., 1 kHz) of a laminated film in which a surface layer is laminated on at least one side of a film made of a styrene polymer having a syndiotactic structure is 0.001 or less. Is preferred.
When the dielectric loss tangent (25 ℃, 1kHz) was greater than 0.001, the good electrical properties of the film made of syndiotactic polystyrene polymer were affected by the properties of the polyester resin of the laminated surface layer. By
It is not preferable because it will be damaged.

Further, in the present invention, a capacitor using a metallized syndiotactic polystyrene-based laminated film in which a metal thin film layer is formed on at least one surface of these laminated films, the slipping off of lubricant in the capacitor manufacturing process is suppressed, In addition, since the running property is excellent, variations in the characteristics of the obtained capacitor are reduced and the yield is improved. Moreover, the obtained capacitor has improved moisture resistance and self-healing property under voltage load.

[0020]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The evaluation method of the film is shown below.

(1) Three-dimensional surface roughness Sλa, SRa Using a stylus-type three-dimensional surface roughness meter (SE-3AK, Kosaka Laboratory Ltd.) to measure the surface of the film, needle radius 2 μm, load
Cutoff value of 0 in the longitudinal direction of the film under the condition of 30 mg.
25 mm, measuring length 1 mm, 2 μm pitch
It is divided into 500 points and the height of each point is calculated by 3D roughness analyzer (SP
A-11). The same operation as above was continuously performed 150 times in the width direction of the film at intervals of 2 μm, that is, over 0.3 mm in the width direction of the film, and the data was taken into the analyzer. Next, Sλa and SRa were obtained using an analyzer.

(2) Glass transition temperature Using THERMOFLEX DSC-8230 manufactured by Rigaku Denki Co., Ltd.
The temperature rising rate was 20 ° C./min, and the sample weight was 5 mg.

(3) Dielectric loss tangent Yokogawa / Hewlett Packard Co. 4192A LF
Using IMPEDANCE ANALYZER, the dielectric loss tangent at 25 ° C and 1kHz was evaluated.

(4) Running property and abrasion resistance of the film The film is formed into a tape having a narrow slit, and the film is rubbed on a metal guide roll and run at high speed for a long time. The magnitude of the tension and the amount of white powder generated on the surface of the guide roll were evaluated and ranked on a scale of 5 as shown below. (A) Runnability 1st class; high tension (very many scratches) 2nd class; slightly high tension (many scratches) 3rd class; medium tension (slightly scratches) 4th class; tension slightly small (almost no scratches) 5th class; Low tension (no scratches) (b) Scratch resistance 1st class: White powder is very much generated 2nd class: White powder is often generated 3rd class: White powder is slightly generated 4th class: White powder is almost not generated 5 Grade: No white powder

(5) Moisture resistance under voltage load A capacitor of 100 V (DC) voltage is applied in an atmosphere of 60 ° C. and 95% RH and aged for 1000 hours to determine the rate of change in capacitance by Yokogawa / Hewlett-Packard. Co., Ltd. 4192A LF
It measured using IMPEDANCE ANALYZER. This is ΔC /
It is shown in C (%), and the smaller the rate of change in capacitance, the better the moisture resistance. Here, C is the capacitance before aging, and ΔC is the value obtained by subtracting the capacitance after aging from the capacitance before aging. The judgment is 5 as shown below.
Graded and ranked. 1st grade; -20> ΔC / C 2nd grade; -10> ΔC / C ≧ −20 3rd grade; −5> ΔC / C ≧ −10 4th grade; 0> ΔC / C ≧ −5 5th grade; ΔC / C ≧ 0

(6) Self-healing property (SH property) A laminated film in which 600 Å of aluminum is vapor-deposited on one side is cut into squares of 1 cm on each side, two sheets are stacked, and further sandwiched by a rubber plate of 2 cm on each side, and 2 kg. Was applied. In this state, a voltage was applied to the vapor-deposited film to cause dielectric breakdown, and the presence or absence of self-healing property was evaluated with 20 samples. 1st grade: No self-healing ability 2nd grade: Almost no self-healing ability 3rd grade: May not have self-healing ability 4th grade: Almost self-healing ability 5th grade: All self-healing ability

(7) Temperature characteristics Yokogawa / Hewlett-Packard Co. 4192A LF
The IMPEDANCE ANALYZER was used to evaluate the dielectric loss tangent at 150 ° C and 1 kHz. The dielectric loss tangent was evaluated and ranked in 5 stages as shown below. 1st grade; 0.05 or more; 2nd grade; 0.01 to 0.05 3rd grade; 0.005 to 0.01 4th grade; 0.001 to 0.005 5th grade; less than 0.001

Examples 1 and 2 Comparative Example 1 (a) Preparation of Polyester Aqueous Solution Bayronal MD1200 (manufactured by Toyobo Co., Ltd.) 20 parts by weight (solid content 25%) Water 36 parts by weight Isopropyl alcohol 36 parts by weight Benzyl alcohol 8 parts by weight

(B) Production of Laminated Film Syndiotactic polystyrene (weight average molecular weight 2500
00) 100 parts by weight of calcium carbonate fine particles as a protrusion-forming agent (average particle size = 1.0 μm, variation = 20%)
Polyethylene terephthalate containing 35% by weight (IV = 0.
62) A polymer chip containing 4.0 parts by weight of resin and a polymer chip containing no protrusion-forming agent in a ratio of 0.2 to 9.8
(Comparative Example 1), 0.5 to 9.5 (Example 1), 1 to 9 (Example 2), mixed, dried and melted at 300 ° C.
Extruded from T-die with 200 μm lip gap, 40 ℃
It adheres to the cooling roll of the
An amorphous sheet of μm was obtained. The amorphous sheet is first preheated to 100 ° C. by a roll and further heated by using four infrared heaters with a surface temperature of 700 ° C.
Stretched 2.0 times in the machine direction at 9 ° C and then 1.25 in the machine direction at 125 ° C.
It was stretched 8 times. The coating solution obtained in (a) above was applied to both surfaces of the uniaxially stretched film by a bar coating method. The film is then preheated to 120 ° C with a tenter and stretched in the transverse direction.
The film was stretched 2.0 times at 120 ° C, then 1.6 times transversely at 150 ° C, and then heat set at 260 ° C. The total thickness of the obtained laminated film is 4 μm, and the total thickness of the surface layers is 0.1 μm.
The coating film was uniform. Aluminum was vapor-deposited on the coated surface of the obtained film by 500 Å to fabricate a roll-type film capacitor. Table 1 shows film and capacitor characteristics
Shown in

Comparative Example 2 Syndiotactic polystyrene (weight average molecular weight 2500
00) 100 parts by weight of calcium carbonate fine particles as a protrusion-forming agent (average particle size = 1.0 μm, variation = 20%)
0.5 to 9.5 by weight ratio of the polymer chip added with 3.5 parts by weight of the polymer chip and the polymer chip not added with the protrusion-forming agent.
Example 1 was repeated except that the mixture was mixed and used. 50 aluminum on the coated surface of the obtained film
A roll-type film capacitor was prototyped by vapor deposition. The film and capacitor characteristics are shown in Table 1.

Examples 3, 4 Comparative Example 3 Syndiotactic polystyrene (weight average molecular weight 2500
00) 100 parts by weight of calcium carbonate fine particles as a protrusion-forming agent (average particle size = 1.0 μm, variation = 20%)
3.5 parts by weight of polymer chips mixed with polymer chips to which no protrusion-forming agent was added at a weight ratio of 1: 9, and polyethylene terephthalate (IV = 0.62) containing no protrusion-forming agent as the surface layer. ) Are fed to separate extruders, melted, joined in a T-die so that polyethylene terephthalate forms both surface layers, extruded from the T-die with a 200 μm lip gap, and chilled to a 40 ° C chill roll. Adhesion, cooling and solidification by the electrophotographic loading method gave an amorphous laminated sheet of 44 μm. Here, the total thickness of the surface layers was set to 5 μm (Example 3), 11 μm (Example 4), and 14 μm (Comparative Example 3). The amorphous sheet was first preheated to 100 ° C by a roll and the surface temperature 70
It is further heated by using four infrared heaters at 0 ℃ and stretched 2.0 times in the machine direction at a film temperature of 139 ℃.
It was stretched 1.8 times in the machine direction at 125 ° C. The coating solution obtained in (a) above was applied to both surfaces of the uniaxially stretched film by a bar coating method. Then, the film was preheated to 120 ° C with a tenter and stretched in the transverse direction at a stretching temperature of 120 ° C by 2.0 times, and further stretched to 150 ° C.
After stretching 1.6 times in the transverse direction at ℃, it was heat set at 260 ℃.
The total thickness of the obtained laminated film was 4 μm. Aluminum was vapor-deposited on the coated surface of the obtained film by 500 Å to fabricate a roll-type film capacitor. Table 1 shows the film and capacitor characteristics.

Examples 5 and 6 Comparative Example 4 Syndiotactic polystyrene (weight average molecular weight 2500
00) 100 parts by weight of calcium carbonate fine particles as a protrusion-forming agent (average particle size = 1.0 μm, variation = 20%)
Polymer chips to which 3.5 parts by weight of PEG was added, polymer chips to which no protrusion-forming agent was added were mixed at a weight ratio of 1: 9, and polyethylene-2,6- Telenaphthalate (Example 5), 50 parts by weight of terephthalic acid and 50 parts by weight of isophthalic acid as carboxylic acid components, resins having different glass transition temperatures by changing the composition ratio of ethylene glycol and 1,4-cyclohexanedimethanol as glycol components (implementation). Example 6 and Comparative Example 4) were fed to respective separate extruders, melted, joined in a T-die so that polyethylene terephthalate formed both surface layers, and extruded from a T-die with a 200 μm lip gap. It was adhered to a chill roll at ℃ by the electrostatic loading method and solidified by cooling to obtain a 44 μm amorphous laminated sheet.
Here, the total thickness of the surface layers was set to 1.0 μm. The amorphous sheet is first preheated to 100 ° C. by a roll, further heated by using four infrared heaters with a surface temperature of 700 ° C., stretched 2.0 times in the machine direction at a film temperature of 139 ° C., and further stretched in the machine direction at 125 ° C. Was stretched 1.8 times. The coating solution obtained in (a) above was applied to both surfaces of the uniaxially stretched film by a bar coating method. Then in the tenter, film 12
It was preheated to 0 ° C., stretched 2.0 times in the transverse direction at a stretching temperature of 120 ° C., further stretched 1.6 times in the transverse direction at 150 ° C., and then heat set at 260 ° C. The total thickness of the obtained laminated film is 4 μm.
Met. Aluminum was vapor-deposited on the coated surface of the obtained film by 500 Å to fabricate a roll-type film capacitor.
Table 1 shows the characteristics of the film and capacitor.

[0033]

[Table 1] From Table 1, the films obtained in Examples 1 to 6 are excellent in runnability and abrasion resistance of the film at the time of manufacturing the film and at the time of manufacturing the capacitor, and have improved moisture resistance under voltage load and self-healing property. It was a syndiotactic polystyrene based laminated film and a capacitor.

[0034]

As described above, according to the present invention, by adopting the constitution as set forth in the claims, the film has excellent running property and abrasion resistance at the time of manufacturing a film or a capacitor. And, a syndiotactic polystyrene-based laminated film and a capacitor having improved moisture resistance under voltage load and self-healing property are provided,
Therefore, the industrial value of the present invention is great.

Claims (6)

[Claims] 1. A laminated film characterized in that a surface layer made of a polyester polymer is formed on at least one side of a film made of a styrene polymer having a syndiotactic structure. 2. The three-dimensional surface roughness SRa of the surface layer is 0.01 (μ
2. The laminated film according to claim 1, wherein m) or more and Sλa (μm) and the glass transition temperature satisfy the following relationship. 4 + 4 x (Tge-Tgc) / Tge ≤ Sλa ≤ 25 + 10 x (Tge-Tgc)
/ Tge where Tge is the glass transition temperature of polyethylene terephthalate Tgc is the glass transition temperature of the surface layer 3. The laminated film according to claim 1, wherein the glass transition temperature of the surface layer satisfies the following relationship. Tgc ≥ 50 x (1 + Ae / A) where Ae is the thickness of the surface layer A is the thickness of the laminated film 4. The thickness of the surface layer is 30 times that of the laminated film.
% Or less, The laminated film according to claim 1, wherein 5. The dielectric loss tangent of a laminated film (25 ° C., 1 kHz)
The laminated film according to claim 1, wherein z) is 0.001 or less. 6. A capacitor comprising a metallized syndiotactic polystyrene-based laminated film having a metal thin film layer formed on at least one surface of the syndiotactic polystyrene-based laminated film according to claim 1.