JPH0611525B2 - Laminated film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a laminated film suitable for packaging various photographic light-sensitive materials, magnetic materials, light-sensitive materials and the like.

[Conventional technology]

As a laminated film used as a packaging material for a photosensitive material such as a photographic light-sensitive material, generally, in addition to completely blocking light,
Gas barrier properties, moisture resistance, physical strength (breaking strength, tear strength, impact drilling strength, gelbotest strength, wear strength, etc.), heat seal suitability (heat seal strength, cut seal strength, hot tack property, foreign matter sheet property, etc.), It is required to satisfy various properties such as antistatic property, lubricity, low dust generation property and flatness.

The present inventor has diligently studied in order to improve a packaging material for a photosensitive substance, and has already disclosed what has improved physical strength by combining two layers of uniaxially stretched film (JP-A-57-6754). ing.

Further, as shown in FIG. 5, a laminated film obtained by laminating a uniaxial molecular orientation thermoplastic resin film layer 16 on both sides of a thermoplastic resin foam sheet layer 5 with an adhesive layer 4 (Japanese Patent Laid-Open No. 59-201848).
Japanese patent publication).

[Problems to be Solved by the Invention]

However, the packaging material disclosed in JP-A-57-6754 has insufficient heat-sealing suitability and is likely to cause curling, and the physical properties of the adhesive material are largely changed due to a change in the thickness of the adhesive layer. If the thickness is too thin, delamination failure will occur, and if the thickness is too thick, the notch effect will be lost and the film will be in the same state as a single-layer film and tear strength will greatly decrease impact punching strength, etc. There was a problem.

On the other hand, the laminated film disclosed in JP-A-59-201848 is very excellent in tear strength and impact puncture strength and also has impact resistance, so it has been put into practical use as a reinforced light-shielding bag replacing a metal can. Uses a uniaxial molecular orientation thermoplastic resin film layer having almost the same softening point on the front and back sides, resulting in poor heat sealing suitability, low sealing strength, and no heat resistant film or Teflon tape between the laminated film and heat sealer. Then, it was melted and fractured, and the light-shielding property and the sealing property could not be secured.

Further, conventional packaging materials such as the above have heat sealability, antistatic properties, laminating suitability, moisture resistance, packaging workability, gas barrier properties, appearance (commercial value), physical strength, heat resistance under sunlight, It had a defect such as front / back distinction in a dark room and delamination strength, and was expensive.

The present invention solves the above problems and has a large physical strength,
It is an object of the present invention to provide an inexpensive laminated film having good bag-making suitability, moisture resistance, gas barrier property, impact puncture strength, breaking strength and the like.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention is one in which an aluminum vacuum deposition flexible sheet and a blocking adhesive film are laminated on both sides of a foamed sheet.

That is, the laminated film of the present invention is a structure in which an aluminum vacuum deposition flexible sheet is laminated on one surface of the thermoplastic resin foam sheet, and a blocking adhesive film is laminated on the other surface, and the aluminum vacuum deposition layer of the flexible sheet is Located on the side of the foamed sheet, the blocking adhesive film is obtained by blocking-adhering two low-softening point layers of two multi-layer coextruded thermoplastic resin films having a high-softening point layer and a low-softening point layer. It is characterized by that.

The thermoplastic resin foam sheet absorbs the impact force from inside and outside, the aluminum vacuum deposition flexible sheet fulfills moisture resistance, gas barrier resistance and light shielding, and the blocking adhesive film is adhered in a flexible state to some extent by blocking and the physical strength. Curl and prevent the occurrence of curling.

The thermoplastic resin foam sheet used in the present invention is, for example, various polyethylene resins and various polypropylene resins, polyolefin resins such as polybutene resin, or ethylene-
Mainly ethylene such as propylene copolymer resin, ethylene-butene copolymer resin, ethylene-vinyl acetate copolymer resin, ethylene-acrylic acid ester copolymer resin and other ethylene-based copolymer resin, chlorinated polyethylene resin and others Copolymer resin as a component, copolymer resin containing propylene as a main component, graft-crosslinked polyolefin resin, or polyamide resin such as one or more of the above mixed resins, polyurethane, natural rubber (manufactured from undiluted latex of rubber) Sponge-like material), SBR, etc. formed into a sheet using a foaming agent.

Preferred foamed sheets that can be effectively applied to the present invention are substantially polystyrene resin, various high density, medium density and low density polyethylene resins, linear low density polyethylene (L-
LDPE) resin, polypropylene resin, propylene / ethylene copolymer resin, ethylene / vinyl acetate copolymer resin, and ethylene-acrylic acid ethylene copolymer resin as a main component are thermoplastic resin foamed sheets.

In particular, expanded polystyrene sheet (expanded polystyrene paper) and expanded polyethylene sheet are preferable in terms of cost and characteristics.

The thermoplastic resin also includes modified resin, crosslinked resin, radiation irradiation resin and the like.

The expansion ratio of the foam sheet is dustproof, cushioning, slippery,
Since it has a large effect on the mechanical strength, it is selected in accordance with the application of the product, but it is in the range of 2 to 50 times. When it exceeds 50 times, the strength of the foamed sheet itself is largely reduced, and when laminated with another film, it causes delamination. Less than twice,
The impact resistance, particularly the gelvotest strength, is lowered, and other properties also lose the effect as a foamed sheet, and it is close to a general film at a high cost.

The aluminum vacuum deposition flexible sheet used in the present invention is a flexible sheet on which an aluminum vacuum deposition layer is formed.

The flexible sheet for forming and supporting the aluminum vacuum-deposited layer has a thickness of 5 to 5 as long as it is a thin layer and has a large physical strength and excellent moisture resistance, gas barrier property and antistatic property.
Any 70 μm paper or film flexible sheet can be used.

As the flexible sheet layer, a thermoplastic resin film, for example, various films such as various polyethylene resins, ethylene copolymer resins, polypropylene resins, polyvinyl chloride resins, polyvinylidene chloride resins, polyamide resins, polycarbonate resins, polyester resins, and the like, and There are films of these modified resins. Further, there are cellulose acetate film, cellophane, polyvinyl alcohol, various papers, non-woven fabrics and the like.

Preferable flexible sheets include various synthetic resin coated papers, synthetic papers, cellophane, thermoplastic resin films, etc. having a thickness of 8 to 50 μm for thinning, cost reduction and securing physical strength, and most preferable are Thickness is 10-40μ
m is a uniaxially or biaxially molecularly oriented polypropylene film, polyester film, high density polyethylene film, polyamide film, polystyrene film, or a mixed resin film of any one of these resins and another resin. As the polypropylene film, an unstretched film is preferable because it has a large physical strength and is inexpensive. An ultrathin reinforced film in which a blow ratio is increased by using a high-density polyethylene resin is particularly preferable because it has a large physical strength and is inexpensive.

When processing an aluminum vacuum-deposited layer on a flexible sheet, an anchor coat agent may be applied to the flexible sheet to provide an anchor coat layer in order to improve adhesion with the aluminum vacuum-deposited layer. Further, surface treatment such as glow discharge treatment, corona discharge treatment, ultraviolet ray irradiation treatment, ozone treatment, chemical treatment, and flame treatment may be performed.

The aluminum vacuum vapor deposition layer processed into a flexible sheet preferably has a thickness in the range of 50 to 1200Å. When the thickness is less than 50Å, the moisture resistance, gas barrier property, and light shielding property are poor, and it is difficult to reduce the charge generated on both surfaces of the metal thin film layer. Also, if the thickness exceeds 1200 Å, antistatic property, moistureproof property, and light shielding property can be secured, but problems such as deterioration of flexible sheet and deterioration of physical strength of the obtained laminated film occur due to cost and heating during vacuum deposition. To do.

The blocking adhesive film used in the present invention is obtained by stacking two multi-layer coextrusion thermoplastic resin films each having a high softening point layer and a low softening point layer, with the low softening point layers being mounted in a blocking manner. In the present invention, the softening point is the Vicat softening point (ASTM D-1525).

The low softening point layer has a low softening point so that it is easily blocked, and the high softening point layer may have a higher softening point than the low softening point layer. The multilayer coextruded thermoplastic resin film may be composed of only these layers, or may be composed of three or more layers in which an intermediate layer or the like is provided therebetween.

To adhere the low softening point layer by blocking, for example, when forming a multi-layer coextrusion blown film, the low softening point layer is roll-pressed by a take-up nip roll, or newly provided at a subsequent stage of the take-up nip roll. The low softening point layers are bonded by blocking with a pressure roll such as an embossing roll or a press roll or a heat roll.

At this time, the round die (ring die) used in the multi-layer coextrusion blown film molding machine is roughly classified into three types: an in-die laminating system, a die outside laminating system, and a laminar flow supply system. Is preferable because of its high interlayer adhesion.

Adhesion by blocking is not completely bonded and fixed as if it was glued, but it is pseudo with some flexibility so that the peel strength is 100 mg / 15 mm width or more without using glue. It is adhered and is effective for preventing bag breakage, improving physical strength, curling, etc. Further, pseudo-adhesion may be carried out in the state of having voids, and in this case, a buffering effect is exerted, which is more preferable.

The blocking adhesive film made from inflation film eliminates the ear loss of conventional laminated films and allows the laminated film to be manufactured at the same time as the blown film is formed, so that the film can be effectively used and stable, wrinkles, and melt fracture almost occur. Good film formability.

As a preferable low softening point layer, an ethylene copolymer resin is used, and specifically, for example, the resins described below.

An L-LDPE resin system having a density of 0.925 g / cm ³ or less and containing 20% by weight or more of an L-LDPE resin. If the density exceeds 0.925 g / cm ³ , even if the temperature during molding is increased, the adhesive strength due to blocking is weak and delamination occurs, making it unusable as a packaging material. Preferably L-LDPE resin 50
% Or more and 0.01 to 2.0% by weight of antioxidant, and the softening point is 110 ° C. or lower.

Further, it is an ethylene acrylic acid ester-based copolymer resin containing 50% by weight or more of an ethylene acrylic acid ester resin having a methyl acrylate and / or ethyl acrylate content of 7% by weight or more and 0.01 to 2.0% by weight of an antioxidant.

Where the ethylene acrylate copolymer resin content is
If it is less than 50% by weight, flexibility is lacking, blocking is less likely to occur, and the antistatic effect and physical strength are also reduced.

When the content of methyl acrylate and / or ethyl acrylate contained in the ethylene acrylic acid ester copolymer resin is less than 7% by weight, blocking is less likely to occur, flexibility is poor, physical strength is low, and antistatic effect is small. .

Further, a preferable low softening point layer is an ethylene vinyl acetate-based copolymer resin having a vinyl acetate content of 5% by weight or more.

If the vinyl acetate content is less than 5% by weight, blocking is less likely to occur and the resin is close to polyethylene resin,
Delamination is likely to occur during bag making.

The thermoplastic resin used as the high softening point layer is preferably a thermoplastic resin having a softening point higher than that of the low softening point layer by 5 ° C. or more, for example, various polyethylene resins, various ethylene copolymer resins, various polypropylene resins, polyvinyl chloride resins. , Polyvinylidene chloride resin, polyamide resin, polycarbonate resin, various polyester resins, and modified resins thereof.

The thermoplastic resin having a high softening point layer is preferably a heat-sealable layer, which is convenient for bag making. In particular, a thermoplastic resin layer containing an ethylene copolymer resin in an amount of 10% by weight or more and a light-shielding substance and a lubricant is preferable. Further, it is preferable that the coefficient of static friction is 0.56 or less in order to improve slippage during lamination with other layers during inflation film formation, during bag making, during product packaging, and to prevent wrinkles.

The thermoplastic resin used as the high softening point layer is preferably a thermoplastic resin having a softening point higher by 5 ° C. or more than the low softening point layer, and the light shielding material, the lubricant, and the ethylene copolymer resin 10% by weight.
Including the above, the sliding angle is 6 to 30 degrees.

The thermoplastic resin film used together with the ethylene copolymer resin is the same as the thermoplastic resin used together with the L-LDPE resin used in the high softening point layer.

Typical examples of the antioxidant that can be added to the high softening point layer and the low softening point layer are shown below.

N-Octadecyl-3 as a phenol type
(3 ', 5'-di-t-butyl 4'hydroxyphenyl) propinate, 2,6-di-t-butyl 4-methylphenol, 2,6 di-t-butyl-p-cresol (BHT), 2 ,
2'-methylenebis (4-methyl-6-t-butylphenol), 4,4'-thiobis (3-methyl6-t-butylphenol), stearyl-β (3,5-di-4-butyl4-
(Hydroxyphenyl) propionate, 1,1,3-tris
(2-Methyl-4-hydroxy-5-t-butylphenyl) butane, tetrakis [methylene-3 (3 ', 5'-di-
t-butyl-4'-hydroxyphenyl) propionate] methane and the like.

Sulfur-based compounds include dilauryl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, laurylstearyl thiodipropionate, distearyl-3'-thiodipropionate, ditridecyl-
Examples include 3,3'-thiodipropionate.

Examples of phosphorus-based compounds include trinonylphenyl phosphite and triphenyl phosphite.

Especially 2,6-di-t-butyl-p-cresol (BHT) and low volatility high molecular weight phenolic antioxidant (trade name lr
eganox 1010, Ireganox 1076, Ionox 330, TopanoICA
Etc.), dilauryl thiodipropionate, distearyl thiodipropionate, dialkis phosphate and the like, and it is effective to use one or more, especially two or more thereof in combination.

The antioxidant is used in an amount of 0.01 to 2.0% by weight. If the amount of the antioxidant is less than 0.01% by weight, the antioxidant effect of the resin becomes small, and the appearance of the resin deteriorates because the lumpy non-uniformity (spots) often occurs due to the resin burning. In addition, the generation of the spots also causes the generation of pressure fog and scratches when the photographic light-sensitive material is packaged. On the other hand, if it exceeds 2.0% by weight, not only the photographic light-sensitive material utilizing the oxidation / reduction effect is adversely affected, but also bleeding out over time causes the appearance to be deteriorated.

A light-shielding substance can be added to one or more layers in order to impart light-shielding properties to the laminated film. The light-shielding substance means a substance that can be kneaded or dispersed in each layer and does not transmit visible light, infrared light, ultraviolet light, or the like. As the light-shielding substance usable in the present invention, various carbon blacks,
Graphite, iron oxide, zinc oxide, titanium oxide, clay,
Aluminum powder, aluminum paste, calcium carbonate, mica, barium sulfate, talc, cadmium-based pigment, rouge, cobalt blue, copper phthalocyanine-based pigment,
Examples thereof include monoazo or polyazo pigments, organic pigments such as aniline black, inorganic pigments and coloring dyes.

Among these light-shielding substances, from the viewpoints of quality, cost, light-shielding ability, etc., color pigments that easily absorb or reflect light, in particular various carbon blacks of black pigments and aluminum powder and aluminum paste of light-reflective light-shielding substances. Those from which lower volatile substances have been removed are preferred.

These light-shielding substances are added to the film by a masterbatch coloring method, a compound coloring method, a die color method, a granulation method or the like.

A lubricant can be added to improve film formability, lubricity, and processability. This lubricant includes various grades of dimethylpolysiloxane as a silicone-based lubricant, oleic acid amide, erucic acid amide, stearic acid amide, bis fatty acid amide, fatty acid metal salt, and alkylamine-based lubricant as a fatty acid amide-based lubricant.

When used for packaging photographic light-sensitive materials, the amount of these lubricants that do not adversely affect the photographic light-sensitive material is 0.01 to 1.0% by weight.
Therefore, not only the single addition but also two types may be used together.
The fatty acid amide-based lubricant preferred in the present invention has 8 to 50 carbon atoms.
And particularly preferably 15 to 35.

INDUSTRIAL APPLICABILITY The laminated film of the present invention can be used for various products as a packaging material. Among them, photographic photosensitive materials, foods, pharmaceuticals, pancakes (strip films) such as magnetic materials (VTR, etc.) and photosensitive materials such as chemical substances can be used. Suitable for packaging.

In particular, silver halide photographic light-sensitive materials, diazo photographic light-sensitive materials, photosensitive resins, self-developing photographic light-sensitive materials, diffusion transfer photographic light-sensitive materials, direct positive photographic light-sensitive materials whose quality is destroyed by slight gas, light and humidity. It is suitable for photographic light-sensitive materials such as materials and photosensitive heat-sensitive materials.

When the laminated film of the present invention is applied as a packaging material to, for example, the packaging of the above photographic light-sensitive material, a single flat bag, a double flat bag, a self-supporting bag, a single gusset bag, a double gusset bag, a laminated film, and a moisture-proof box inside, It can be used in all known forms such as inside a light-room loading light-shielding magazine and leader paper.

The bag-making method is a conventionally known plastic film sealing method such as heat sealing, fusing sealing, impulse sealing, ultrasonic sealing, or high-frequency sealing depending on the properties of the laminated film used. Note that it is also possible to make a bag using an appropriate adhesive or pressure-sensitive adhesive.

[Action]

In the present invention, since the thermoplastic resin foam sheet is the center, and the aluminum vacuum deposition flexible sheet is arranged on one side and the blocking adhesive film is arranged on the other side, there is no curling and great durability against impact from inside and outside. And has heat-sealing properties, bag-making suitability, and physical strength.

Further, since the flexible sheet protects the aluminum vacuum-deposited layer, the moisture-proof property, the gas barrier property, and the light-shielding property are secured together with the effect of improving the heat-sealing property.

〔Example〕

An embodiment of the laminated film of the present invention will be described based on FIGS. 1 to 4.

1 to 4 are partial cross-sectional views showing the layer structure of the laminated film of the present invention.

The laminated film of FIG. 1 is a blocking adhesive film 9
And the aluminum vacuum-deposited layer 2 of the aluminum vacuum-deposited flexible sheet 3 are laminated with the thermoplastic resin foam sheet 5 via the adhesive layers 4 and 4 to form a nine-layer structure.

The blocking adhesive film 9 includes a thermoplastic resin film 6 as a high softening point layer and an L-LD as a low softening point layer.
Multi-layer coextrusion thermoplastic resin films 8 and 8 with the PE resin-based layer 7 are blocking-bonded with the L-LDPE resin-based layers 7 and 7. The aluminum vacuum deposition flexible sheet 3 is obtained by vacuum-depositing the aluminum vacuum deposition layer 2 on the flexible sheet 1.

The laminated film of FIG. 2 is the same as the laminated film of FIG. 1 except that the ethylene acrylic acid ester-based copolymer resin layer 10 is used as the low softening point layer.

The laminated film of FIG. 3 is the same as the laminated film of FIG. 1 except that the ethylene vinyl acetate copolymer resin layer 11 is used as the low softening point layer.

Instead of using the adhesive layer 4, the laminated film of FIG.
The laminated film is the same as the laminated film of FIG. 1 except that the surface of the thermoplastic resin foam sheet 5 is melted and bonded by using this molten layer.

FIG. 6 and FIG. 7 are partial cross-sectional views showing the layer structure of the laminated film of the comparative example.

The laminated film of FIG. 6 comprises an aluminum vacuum vapor-deposited multiaxial molecular orientation film 13 composed of a multiaxial molecular oriented film 12 and an aluminum vacuum vapor deposition layer 2, an L-LDPE resin-based film 7 and an HDPE resin-based film 14. The multilayer coextruded film 8 is laminated via the adhesive layer 4.

The laminated film of FIG. 7 is an aluminum vacuum-deposited multiaxial molecular orientation film 13 and a light-shielding polyolefin resin film.
15 is composed of three layers directly laminated by the extrusion laminating method with the aluminum vacuum deposition layer 2 inside.

Invention Product I Invention product I corresponds to the layer structure of FIG.

In the invention product I, the high softening point layer 6 is made of HDPE resin (density of 0.
954 g / cm ³ , MI 1.1 g / 10 minutes, Vicat softening point 126 ° C.) 20% by weight, L-LDPE resin (density 0.920 g / cm ³ , MI 2) which is a copolymer of ethylene and 4-methylpentene-1. .1g / 1
0 minutes, Vicat softening point 100 ° C.) 76.95% by weight, carbon black 3% by weight, and oleic acid amide 0.05% by weight.

The L-LDPE resin-based layer 7 as a low softening point layer is an L-LDPE resin (density 0.890 g / cm ³ , MI 1.0 g / 10 minutes, Vicat softening point 75 ° C.) which is a copolymer of ethylene and butene-1. ) 2
0% by weight, L-LDPE resin which is a copolymer of ethylene and 4-methylpentene-1 (density 0.920 g / cm ³ , MI 2.1 g
/ 10 minutes, Vicat softening point 100 ° C) 80% by weight.

The multi-layer co-extrusion resin film 8 was obtained by a two-layer co-extrusion inflation film molding method.

As the flexible sheet 1 of the aluminum vacuum deposition flexible sheet 3, a biaxially stretched nylon resin film having a thickness of 15 μm was used.

The aluminum vacuum deposition layer 2 has a thickness of 400 Å.

Comparative product I Comparative product I corresponds to the layer structure of FIG.

In Comparative Product I, the aluminum vacuum vapor-deposited multiaxial molecular orientation film 13 was a biaxially stretched polyester resin film having a thickness of 12 μm, and the aluminum vacuum vapor deposition layer 2 had a thickness of 400 Å.

The L-LDPE resin film 7 is composed of 5% by weight of LDPE resin, 3% by weight of furnace carbon black, ethylene.
4-methylpentene-1 copolymer resin (Ultzex 20
20 L, MI 2.1 g / 10 min, density 0.924 g / cm ³ , 92% by weight (manufactured by Mitsui Petrochemical), and a thickness of 40 μm. The HDPE resin-based film 14 comprises 3% by weight of furnace carbon black and HDPE resin (Hi-Zex 3300
F, MI 1.1 g / 10 minutes, density 0.954 g / cm ³ (manufactured by Mitsui Petrochemical Co., Ltd.) 97% by weight, and formed to a thickness of 40 μm.

As the adhesive layer 4, an LDPE resin extrusion laminate adhesive layer having a thickness of 15 μm was used.

Comparative product II Comparative product II corresponds to the layer structure of FIG.

In the comparative product II, the light-shielding polyolefin resin film 15
Is 3% by weight of carbon black, ethylene / 4-methylpentene-1 copolymer resin (Ultox 2080C, MI
7 g / 10 minutes, density 0.920 g / cm ³ , 97% by weight (manufactured by Mitsui Petrochemical), and a thickness of 80 μm.

The aluminum vacuum-deposited multiaxial molecular orientation film 13 is the same as the comparative product I.

Conventional Product I Conventional product I corresponds to the layer structure shown in FIG.

In the conventional product I, the thermoplastic resin foam sheet 5 has a thickness of 1 mm.
Using a cross-linked LDPE resin foam sheet with a foaming ratio of 30 times,
As the uniaxial molecular orientation thermoplastic resin film 16, a light-shielding uniaxial molecular orientation HDPE resin film containing 4.5% by weight of carbon black and having a thickness of 45 μm was used.

As the adhesive layer 4, an LDPE resin extrusion laminate adhesive layer having a thickness of 15 μm was used.

The above values are those of the following test method.

MI (g / 10 min); JIS K6760 = ASTM D1238 (190 ° C measurement) Density (g / cm ³ ); JIS K6760 = ASTM D1505 Vicat softening point (° C); JIS K7206 = ASTM D1525 Table 1 shows the experimental results. Show.

The evaluation is as follows.

◎… Excellent 〇… Excellent ●… Available (within practical limits) ▲… Problem (needs improvement) ×… Not practical * A curling A circular test sample with a diameter of 10 cm is made with the laminated film to be tested. 1 kg in an atmosphere with a temperature of 20 ° C and a humidity of 65% RH
After being left under the load plate for 24 hours, each circular test sample was left unloaded on the flat plate for 24 hours in the atmosphere under the above conditions, and then evaluated in the curling state. * B Suitable for bag making By heat sealing Comprehensively evaluate the strength, appearance, pinhole prevention, front / back distinction, antistatic property, delamination strength, etc. of the seal part when making a sealed bag. * C peeling electrification voltage: 35 mm wide, 1350 mm long film to be tested Endless belt, and the peeling electrification voltage when this belt was sent between a SUS roller (stainless steel) with a load of 500 g and a SUS roller at a speed of 12 m / min by a voltmeter (Shinto Kagaku KK
The value measured by (made by).

* D Heat retention Judged by measuring the temperature rise in a sealed bag made with each packaging material after leaving it in the sunlight (80,000 lux) for 3 hours with a thermistor. * E Heat seal suitability Hot tack, foreign matter Sealability, heat seal strength,
Judging from total heat sealing suitability such as heat seal strength retention property over time, heat sealable allowable temperature range, etc. [Effect of the invention] Since the present invention is configured as described above, curling is small, physical strength is large, and bag making suitability, It is possible to provide a laminated film for a fluorescent substance, which has excellent antistatic properties, heat retention properties, and heat seal suitability.

[Brief description of drawings]

1 to 4 are partial cross-sectional views showing the layer structure of an embodiment of the laminated film of the present invention. FIG. 5 is a partial cross-sectional view showing a layer structure of a conventional laminated film. FIG. 6 and FIG. 7 are partial cross-sectional views showing the layer structure of the laminated film of the comparative example. 1 ... Flexible sheet 2 ... Aluminum vacuum deposition layer 3 ... Aluminum vacuum deposition flexible sheet 4 ... Adhesive layer 5 ... Thermoplastic resin foam sheet 6 ... High softening point layer 7 ... L-LDPE resin-based layer 8 ...... Multi-layer coextrusion resin film 9 …… Blocking adhesive film 10 …… Ethylene acrylate ester copolymer resin film 11 …… Ethylene vinyl acetate copolymer resin film

Claims (1)

[Claims] 1. A thermoplastic resin foam sheet having a structure in which an aluminum vacuum deposition flexible sheet is laminated on one surface and a blocking adhesive film is laminated on the other surface, and the aluminum vacuum deposition layer of the flexible sheet is on the foam sheet side. The blocking adhesive film is characterized in that two low-softening point layers of two multi-layer coextruded thermoplastic resin films having a high-softening point layer and a low-softening point layer are blocked. Laminated film