JPH0818400B2 - Packaging material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a packaging material suitable for packaging a relatively heavy article such as a film roll film for movies among various photographic photosensitive materials, photosensitive materials, electronic parts and the like. It is a thing.

[Conventional technology]

In general, as a packaging material for advanced technology products such as photographic photosensitive materials, 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 sealing suitability (heat sealing strength, cut sealing property, hot tack property, foreign substance sealing property, etc.), antistatic property, lubricity, low dust generation property, flatness, etc. It It is extremely difficult to combine these properties with a single film material, and conventionally, a packaging material having a plurality of layers has been used.

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

Further, in a three-layer laminated film obtained by laminating a uniaxial molecular orientation thermoplastic resin film on both sides of a sheet-shaped foam, the thickness of the sheet-shaped foam is 0.3 to 2.0 mm, and the expansion ratio is 5 to 50 times. And the bilayer uniaxial molecular orientation film is
The molecular orientation axes are intersected at an angle of 30 degrees or more, so that they are heat-melt-bonded on both sides of the foam with or without a heat-melt adhesive layer, and the thickness of the laminated film is 40 of the theoretical sum of each layer. ~ 85
It has already been disclosed a laminated film excellent in impact hole rake strength and gelvotest strength compressed to a thickness of 0.1% (residual thickness ratio) and small curling, which is particularly excellent as a packaging material for heavy objects (JP-A-59-201848). Issue).

[Problems to be Solved by the Invention]

In such a packaging material composed of a plurality of layers, since each film layer is laminated with an adhesive layer or laminated by coextrusion, each layer is completely integrated and adhered to be hard, and the physical strength is small. The curl was large. In addition, there is an inherent problem that a step of providing an adhesive layer is required, resulting in a large process loss and a large process cost.

In addition, it is difficult to distinguish between the front and the back under a safelight, which is a packaging material for photosensitive materials, and not only does the quality of the photosensitive material in the packaging material deteriorate due to the high temperature caused by sunlight, but it also causes melt adhesion under strong sunlight in the summer. There were things.

Further, when a co-extruded T-die film or an inflation film is laminated to form a laminated film having a plurality of constitutions, trimming loss is large and it is uneconomical.

The present invention solves the above problems, is inexpensive and has an excellent appearance, has a large physical strength and a small curl, is flexible, and has front and back distinguishability under safelight, temperature rise prevention under sunlight, and the like. The purpose is to provide good packaging materials.

[Means for solving the problem]

In order to achieve the above object, the present invention has a light-reflecting flexible sheet layer and a film layer pseudo-adhered by blocking, which has been conventionally regarded as a failure, without using an adhesive layer. It comprises a pseudo-adhesive layer in which two layers of ethylene vinyl acetate-based copolymer resin film layers which are inner layers of a multi-layer coextrusion film are adhered by blocking, and a light-reflecting flexible sheet layer, preferably a light-reflecting flexible sheet layer. And a multilayer coextrusion blocking laminated film layer having a pseudo adhesive layer in which the inner layers of the multilayer coextrusion inflation film are adhered by blocking, the multilayer coextrusion inflation film having an inner layer having a vinyl acetate content of 5% by weight or more. Of the ethylene vinyl acetate copolymer resin film layer and an outer thermoplastic resin film layer containing an antiblocking substance.

The light-reflecting flexible sheet layer is formed by adding a light-reflecting light-shielding substance to a metal foil and / or a metal thin film processed flexible sheet layer such as aluminum vacuum-deposited film, aluminum vacuum-deposited paper and / or sputtering film and / or thermoplastic resin. For example, a light-shielding light-shielding film layer is used.

The thermoplastic resin for the light-reflective light-shielding film layer is a polyolefin resin, a polyester resin, a polyamide resin, or the like. Among them, the polyolefin resin is preferable, and particularly, a high-density polyethylene (hereinafter referred to as HDPE) having a large moisture resistance is used. Displayed) type resin, polypropylene type resin, L
-LDPE resins or mixed resins containing these resins are preferable.

As the light-reflective light-shielding substance, metal powder, white or pale yellow pigment, or the like is used. The metal powder is aluminum powder,
Aluminum paste, tin powder, nickel powder, zinc powder, or powder of these metal alloys or metal compounds.

Here, the aluminum paste means that when an aluminum powder is produced by a known method such as a ball mill method, a stamp mill method or an atomizing method, mineral spirits and a small amount of higher fatty acids such as stearic acid or oleic acid and higher fatty acid derivatives are used. It was made into a paste in the presence. In the light-reflecting light-shielding film layer of the present invention, this aluminum paste and a polyolefin-based thermoplastic resin (various polypropylene resin, various polyethylene resin, EVA resin, EEA resin, EAA resin, etc.) are heat-kneaded to reduce a low volatile substance (mainly bad odor). The strong mineral spirit) is removed by heating and / or vacuum pump etc. and used as aluminum paste compound resin, aluminum paste masterbatch resin.

In particular, it is preferable to use it as an aluminum paste masterbatch resin in order to eliminate adverse effects and odors on the photographic light-sensitive material.

Particularly preferred is the use of 0.1 to 1 higher fatty acid and / or higher fatty acid derivative without the use of a solution such as mineral spirits.
It is a resin obtained by kneading a thermoplastic resin with a necessary amount of metal powder in which 0 to 99.9% by weight of aluminum powder is completely covered with a higher fatty acid and / or a higher fatty acid derivative around 90 to 99.9% by weight of aluminum.

In addition to aluminum powder, molten aluminum is powdered by atomizing method, granulating method, rotary disc dropping method, evaporation method, etc., and aluminum foil is crushed by a ball mill method, a stamp mill method or the like into flakes. Including what you did. Since the aluminum powder alone is unstable, various known treatments for making the surface of the aluminum powder inactive, for example, surface coating of the aluminum powder with a higher fatty acid or the like is applied.

The amount of the metal powder added is preferably 0.1 to 20% by weight, and particularly preferably 1 to 6% by weight.

The thickness of the light-reflecting flexible sheet layer is preferably 5 μm or more, and particularly preferably 10 μm or more, from the viewpoint of suitability for lamination.

The multi-layer coextrusion blocking laminated film layer has a pseudo adhesive layer internally pseudo bonded by blocking. This pseudo-adhesive layer consists of an ethylene vinyl acetate-based copolymer resin film layer, and is not completely bonded and fixed as if adhered by the adhesive layer, but there is no problem during lamination or bag making. It has a weak adhesive strength and is pseudo-bonded in a flexible state to prevent curling while improving packaging workability and physical strength.

The ethylene vinyl acetate-based copolymer resin film layer has a vinyl acetate content of 5% by weight or more.

To pseudo-adhere this ethylene vinyl acetate copolymer resin film layer by blocking, for example, when forming a multilayer coextrusion inflation film by a multilayer coextrusion inflation method, in the subsequent stage of the take-up nip roll or the take-up nip roll. This is performed by pressing the ethylene vinyl acetate-based copolymer resin film layer with a newly provided pressure-bonding roll or the like.

Round die method The round die (ring die) used in the multi-layer coextrusion blown film molding machine is roughly classified into an in-die stacking method, a die outside stacking method, and a laminar flow supply method. It is preferable because it has high adhesion.

Further, in the case of the blown film, the ear loss unlike the conventional laminated film is eliminated and the laminated film can be produced at the same time as the blown film can be formed, so that the film can be effectively used and is stable, and wrinkles and melt fractures hardly occur. Good film formability.

A thermoplastic resin film layer is laminated on the outside of the ethylene-vinyl acetate copolymer resin film layer, and the thermoplastic resin film layer contains an antiblocking substance. If the antiblocking substance is not contained, the multilayer coextruded film is wound up and once stored for 1 hour, the entire roll causes blocking and becomes unusable.

Known films of various polyethylene resins, ethylene copolymer resins, polypropylene resins, polyvinyl chloride resins, polyvinylidene chloride resins, various polyamide resins, polycarbonate resins, various polyester resins, etc. if they contain anti-blocking substances , And films made of these modified resins and mixed resins can be used.

The thermoplastic resin film layer preferably has a softening point (ASTM D-1525) higher than that of the ethylene-vinyl acetate copolymer resin film layer by 5 ° C. or more in order to improve suitability for bag making and to cause blocking.

Further, the thermoplastic resin film layer, during inflation film molding, during lamination with other film layers, during bag making,
It is preferable that the sliding angle be 6 to 30 degrees in order to improve the slippage during product packaging and prevent wrinkles.

This slip angle is obtained by cutting out a part of the laminated film to be tested and attaching it to the bottom surface of a metal plate block with a length of 75 ^mm × a width of 35 ^mm and a load of 2000 g, with the laminated film surface of the block on the inclined surface. Then, the inclination angle of this inclined surface is changed and the angle at which the block starts to slide is read.

If the slip angle is less than 6 degrees, slippage occurs during winding of the laminated film, causing winding deviation, which makes practical application difficult. In addition, stacking packaging materials using the packaging material of the present invention tends to cause load collapse.

Further, if the sliding angle exceeds 30 degrees, not only does the frictional resistance with the guide plate increase during film forming, wrinkles and streaks are generated, but also many troubles are likely to occur in the processing and packaging process for packaging products.

Further, the thermoplastic resin film layer has a softening point (ASTM D 1) of 5 ° C or higher than that of the ethylene vinyl acetate-based copolymer resin film layer in order to facilitate bag-making and blocking.
525) is preferably high.

A light-shielding substance may be added to the ethylene-vinyl acetate copolymer resin film layer or the thermoplastic resin film layer in order to secure light-shielding properties.

This light-shielding substance can be kneaded or dispersed in each layer,
It does not transmit visible light, infrared rays, and ultraviolet rays. Examples of the light-shielding substance that can be used in the present invention include various carbon blacks, graphite, iron oxide, zinc oxide, titanium oxide, clay, aluminum powder, aluminum paste, calcium carbonate, mica, barium sulfate, talc,
Examples thereof include cadmium pigments, red iron oxide, cobalt blue, copper phthalocyanine pigments, 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., a coloring substance that easily absorbs or reflects light, particularly a carbon black of various pigments, aluminum powder of metal powder, and a lower volatile substance than the aluminum paste are used. Those removed are preferred.

As a method of blending these light-shielding substances into each layer, there are a masterbatch coloring method, a compound coloring method, and the like, which have been often performed conventionally. The light-shielding substance is a powdery colorant as a usage form depending on the resin used, the machine used, the cost, etc.
It is classified into paste colorants, wet colorants, masterbatches, dyes and pigments, colored pellets and the like.

And, in terms of securing the light-shielding property, cost and physical strength are improved, the average particle diameter is preferably 200 mμ or less furnace carbon black, acetylene carbon black as a light-shielding substance having an expensive antistatic cost,
Ketjen carbon black and graphite are preferred. If necessary, it is also preferable to mix and use two or more kinds of light-shielding substances according to the required characteristics. Even in this case, 0.5g / m ^{2 to} 50g / m of the light-shielding substance with an average particle size of 200mμ or less
It is preferable to include it in ^two laminated films. On the other hand, among these carbon blacks, pH 5-9, average particle size 10-1
20mμ is preferred, especially pH 6-9, average particle size 50
Furnace carbon black of mμ or less is preferable. By using such a pH and particle size,
Fog is less likely to occur, and sensitivity is less likely to increase or decrease.
It is possible to obtain a packaging material having a large number of advantages such as a large light-shielding ability, few pinholes due to carbon black lumps and fisheyes, improved physical strength, and improved heat sealability.

Although there are various forms of blending the light-shielding substance in each layer as described above, the masterbatch method is preferable in terms of cost reduction, prevention of contamination of the workplace, and the like.

Further, if pseudo adhesion can be secured, it is preferable to add a lubricant to each layer in order to improve film moldability, lubricity, and processability. Examples of known lubricants include waxes, fatty alcohols, glycerin fatty acid esters, fatty acid amides, silicones, fatty acid esters with lower alcohols, fatty acids, paraffins and α-olefin-maleic acid copolymers.

Representative lubricants and their manufacturers are described below, but the invention is not limited thereto.

(1) Silicone-based lubricants; various grades of dimethylpolysiloxane (Shin-Etsu Silicone, Toray Silicone), etc. (2) Oleic acid amide-based lubricants: Armoslip CP (Lion Akzo), Neutron (Nippon Seika), Neutron E -18 (Nippon Seika), Amide O (Nitto Kagaku),
Alfro-E-10 (Nippon Yushi), Diamond Mid O-200
(Nippon Kasei), Diamid G-200 (Nippon Kasei), etc. (3) Erika acid amide lubricant; Alfuro-P-10 (Nippon Yushi), Neutron S (Nippon Seika), etc. (4) Stearic acid amide Lubricant; Alfro-S-10
(Nippon Yushi), Neutron 2 (Nippon Seika), Diamid 200 (Nippon Kasei), etc. (5) Bis fatty acid amide lubricant; Bisamide (Nippon Kasei), Diamid 200 bis (Nippon Kasei), Armowax EBS ( (Lion Akzo) etc. (6) Alkylamine lubricants; Electrostripers
There is TS-2 (Kao soap) etc.

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, and they may be used alone or in combination of two kinds. The preferred fatty acid amide lubricant of the present invention has 8 carbon atoms.
~ 50, particularly preferred 15-35.

The multi-layer coextrusion blown film is an ethylene vinyl acetate-based copolymer resin film layer and a thermoplastic resin film as long as it comprises at least the above ethylene vinyl acetate-based copolymer resin film layer and the thermoplastic resin film layer. An intermediate layer may be laminated between the layers.

Then, a multilayer coextrusion blocking laminated film layer is formed by pseudo-adhering the inner layers of the multilayer coextruded inflation film to each other by blocking, and the multilayer coextruded blocking laminated film layer and the light reflection flexible sheet layer are laminated. There is. To laminate the multilayer coextrusion blocking laminated film layer and the light reflective flexible sheet layer, various known methods may be used,
Thermal bonding method (hot plate bonding method, flame treatment bonding method, impulse bonding method, ultrasonic bonding method), adhesive method (wet laminating method, dry laminating method, hot melt laminating method, extrusion laminating method, coextrusion laminating method) Law), etc. are used.

Typical adhesives include various polyolefin-based thermoplastic resin hot melt adhesives, ethylene-propylene copolymer resins, ethylene-vinyl acetate copolymer resins, ethylene copolymers such as ethylene-ethyl acrylate copolymers. Resin, ethylene-acrylic acid copolymer resin, thermoplastic resin such as ionomer resin, etc. There are heat melting adhesives and other heat melting type rubber adhesives. Emulsion or latex adhesive, and a typical example of emulsion adhesive is
Polyvinyl acetate resin, vinyl acetate-ethylene copolymer resin, vinyl acetate resin and acrylic ester copolymer resin, vinyl acetate resin and maleic ester copolymer resin, acrylic acid copolymer resin, ethylene-acrylic acid copolymer There are emulsions such as polymer resins. Typical examples of latex type adhesives include natural rubber, styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR),
There is rubber latex such as chloroprene rubber (CR).
Also, as adhesives for dry lamination, there are isocyanate adhesives, urethane adhesives, polyester adhesives, and blends of microcrystalline wax, ethylene-vinyl acetate copolymer resin, ethylene-ethyl acrylate copolymer resin, etc. Known adhesives such as hot-melt laminating adhesives, pressure-sensitive adhesives, and heat-sensitive adhesives can also be used. More specifically, the polyolefin resin adhesive for extrusion lamination is various polyethylene resins, polypropylene resins, polyolefin resins such as polybutylene resin and ethylene copolymers and ethylene copolymers (EVA, EEA, etc.) other than resins, Like L-LDPE resin, ethylene partially copolymerized with other monomer (α-olefin), Surlyn from Dupont, ionomer resin (ion copolymer resin) such as Himilan from Mitsui Polychemical and Mitsui. There is Admer (adhesive polymer) of Petrochemical Co., Ltd., etc. Other UV curable adhesives have also begun to be used recently.

In particular, LDPE resin and L-LDPE resin are preferable because they are inexpensive and have excellent laminating suitability. Further, a mixed resin in which two or more kinds of the above-mentioned resins are blended to cover the defects of each resin is particularly preferable.

The thickness of the adhesive layer by the extrusion lamination method using a thermoplastic resin is usually 6 μm to 50 μm, preferably 10 μm to 20 μm, but it is based on the cost, the adhesive strength, the laminating speed, the total thickness of the laminate, etc. However, the numerical value is not particularly limited.

The packaging material of the present invention can be used for packaging various products, and is particularly suitable for packaging photosensitive materials such as photographic light-sensitive materials, foods, pharmaceuticals, and chemical substances.

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, photosensitive heat-sensitive materials, etc., whose quality is destroyed by slight gas, light and humidity. It is suitable for the photographic light-sensitive material.

When the packaging material of the present invention is applied to, for example, the above-mentioned 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 sticking of a light chamber loading light-shielding magazine, a moisture-proof / light-shielding bag of a light chamber loading light-shielding magazine, and leader paper.

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

[Action]

In the packaging material of the present invention, the light-reflecting flexible sheet layer improves the printability and the front / back distinction under safelight, and prevents the temperature rise under sunlight, and the multilayer coextrusion blocking laminated film layer has a tear strength. It has improved curl and reduced curl.

〔Example〕

Hereinafter, embodiments of the packaging material according to the present invention will be described with reference to FIGS. 1 to 7.

1 to 7 are partial cross-sectional views showing the layer structure of a typical packaging material of the present invention.

The packaging material shown in FIG. 1 is a light reflecting flexible sheet layer 1
A multi-layer coextrusion blocking laminated film layer 2 laminated with an adhesive layer 3. The multi-layer coextrusion blocking laminated film layer 2 is an inner layer of the ethylene vinyl acetate-based copolymer resin film layers 4 and 4 and the same film outer layer. 4 of the thermoplastic resin film layers 5 and 5, and the ethylene vinyl acetate copolymer resin film layer 4 and the thermoplastic resin film layer 5 are formed by a circular die method two-layer coextrusion inflation film molding machine. Two-layer coextrusion film 6
Is. Then, the ethylene vinyl acetate-based copolymer resin film layers 4, 4, which are the inner layers, are pseudo-bonded by blocking.

The packaging material of FIG. 2 is the same as the packaging material of FIG. 1 except that the thermoplastic resin film layer 5a is used as the outer layer having a light shielding property.

The packaging material of FIG. 3 is the same as the packaging material of FIG. 1 except that the thermoplastic resin film layer 5a and the ethylene vinyl acetate-based copolymer resin film layer 4a having a light shielding property are used.

The packaging material of FIG. 4 is the same as the packaging material of FIG. 1 except that the ethylene vinyl acetate-based copolymer resin film layer 4a having a light shielding property is used.

The packaging material of FIG. 5 is made up of 6 layers including an ethylene vinyl acetate-based copolymer resin film layer 4.4 as an inner layer, an intermediate layer 7.7, and a thermoplastic film layer 5.5 as an outer layer. The ethylene vinyl acetate-based copolymer resin film layer 4, the intermediate layer 7, and the thermoplastic resin film layer 5 are a three-layer coextrusion film 8 formed by a round die method three-layer coextrusion inflation film forming method. The ethylene vinyl acetate-based copolymer resin film layers 4 and 4 are pseudo-bonded by blocking.

The packaging material of FIG. 6 is the same as the packaging material of FIG. 5 except that each layer has a light-shielding property except for the adhesive layer 3.

The packaging material of FIG. 7 has an ethylene vinyl acetate copolymer resin film layer 4.4 as an inner layer, an intermediate layer 71.71, an intermediate layer 72a.72a having a light shielding property, and an outer layer having a light shielding property. Consisting of the thermoplastic resin film layers 5a, 5a, these ethylene vinyl acetate-based copolymer resin film layer layer 4,
The intermediate layers 71 and 72a and the thermoplastic resin film layer 5a are a four-layer coextrusion film 9a formed by a round die method four-layer coextrusion inflation film molding method. The ethylene vinyl acetate-based copolymer resin film layers 4 and 4 are pseudo-bonded by blocking.

Next, the experimental results comparing the special products of the invention products I to V and the comparative product I will be described.

Product I of the Invention Product I of the invention corresponds to the layer configuration in FIG.

As the light-reflecting flexible sheet layer 1, an aluminum vacuum-deposited biaxially stretched nylon film having a thickness of 400 μm and an aluminum vacuum deposited layer having a thickness of 400 μm was used. The laminated structure was such that the biaxially stretched nylon film was on the outside and the aluminum vacuum deposition layer was on the inside.

The ethylene vinyl acetate-based copolymer resin film layer 4 is
Vinyl acetate content (saponification method) 14% by weight, MFR (ASTM D
-1238 modified) is 3.5g / 10 minutes, density (ASTM D-1505) is 0.93g
/ cm ^3, and 70 wt% EVA resin Vicat softening point 68 ° C., a density ethylene copolymer resin of ethylene and octene-1 is 0.920g / cm ^3, MI is 2 g / 10 min Vicat softening point 96 It is composed of 30% by weight of L-LDPE resin at a temperature of ℃, and has a thickness of 25 μm.

The thermoplastic resin film layer 5a has a density of 0.954 g / cm ³ , MI
Is 1.1 g / 10 minutes, the Vicat softening point is 20% by weight of HDPE resin having a temperature of 126 ° C., which is a copolymer resin of ethylene and 4-methylpentene-1, the density is 0.920 g / cm ³ , and the MI is 2.1 g / 10 minutes, 76.95% by weight of L-LDPE resin having a Vicat softening point of 100 ° C, 3% by weight of carbon black, and 0.05% by weight of oleic acid amide.
And has a thickness of 25 μm and a sliding angle of 9 to 30 degrees.

The adhesive layer 3 is LDP having MI of 5.1 g / 10 minutes and density of 0.919 g / cm ³ .
Composed of E resin. It is an extrusion lamination adhesive layer having a thickness of 15 μm.

Inventive product II The inventive product II corresponds to the layer structure shown in FIG.

As the light-reflecting flexible sheet layer 1, an aluminum vacuum vapor-deposited biaxially stretched polyester film obtained by forming a 400 μm-thick aluminum vacuum vapor-deposited layer on a 12 μm-thick biaxially stretched polyester film was used. The biaxially stretched polyester film is on the outside and the aluminum vacuum deposition layer is on the adhesive layer 3 side (inside).

Ethylene vinyl acetate-based copolymer resin film layer 4 Vinyl acetate content (saponification method) is 19% by weight, MFR is 2.5 g / 10 minutes,
60% by weight of EVA resin with a density of 0.94 g / cm ³ and a Vicat softening point of 64 ° C., an ethylene copolymer resin of ethylene and butene-1 with a density of 0.890 g / cm ³ and an MI of 1 g / 10 min. It is composed of 38% by weight of L-LDPE resin having a softening point of 58 ° C. and 2% by weight of carbon black, and has a thickness of 25 μm.

The thermoplastic resin film layer 5a is the same as the product I of the present invention.

 The adhesive layer 3 is the same as the product I of the present invention.

Invention product III Invention product III also corresponds to the layer structure of FIG.

The light reflecting flexible sheet layer 1 is the same as the product I of the present invention.

The ethylene vinyl acetate-based copolymer resin film layer 4a,
Vinyl acetate content (saponification method) 14% by weight, MFR 1.4g / 10
Min, density 0.93g / cm ³ , EVA resin with Vicat softening point 70 ℃
60% by weight, ethylene-butene-1 ethylene copolymer resin having a density of 0.906 g / cm ³ , MI of 0.8 g / 10 min, 37% by weight of L-LDPE resin with a Vicat softening point of 84 ° C and carbon black It is composed of 3% by weight and has a thickness of 25 μm.

The thermoplastic resin film layer 5a is the same as the product I of the present invention.

 The adhesive layer 3 is the same as the product I of the present invention.

Inventive product IV Inventive product IV also corresponds to the layer structure shown in FIG.

As the light-reflecting flexible sheet layer 1, an aluminum vacuum vapor-deposited biaxially stretched polypropylene film having a thickness of 400 μm and an aluminum vacuum vapor-deposited layer having a thickness of 400 μm was used. The biaxially stretched polypropylene film is on the outside and the aluminum vacuum deposition layer is on the side of the adhesive layer 3 (inside).

The ethylene vinyl acetate-based copolymer resin film layer 4a,
It is made of the same resin composition as the product II of the present invention and has a thickness of 30 μm.

The thermoplastic resin film layer 5a has a density of 0.923 g / cm ³ , MI
Is 2.4g / 10 minutes, 5% by weight of LDPE resin with a Vicat softening point of 92 ° C, and 92% by weight of HDPE resin with a density of 0.964g / cm ³ , MI of 0.4g / 10 minutes, and a Vicat softening point of 128 ° C. , Carbon black 3% by weight, and has a thickness of 20 μm.

 The adhesive layer 3 is the same as the product I of the present invention.

Inventive product V Inventive product V also corresponds to the layer structure shown in FIG.

Light reflective flexible sheet layer 1 has a density of 0.964 g / c
Aluminum vacuum-deposited diagonal uniaxial molecular orientation HDPE film with a thickness of 400 Å aluminum vacuum vapor-deposited layer on 35 μm diagonal uniaxial molecular orientation HDPE film using HDPE resin with m ³ and MI of 0.4 g / 10 min. Using. The oblique uniaxial molecular orientation HDPE film is on the outer side, and the aluminum vacuum deposition layer is on the adhesive layer 3 side (inner side).

The ethylene vinyl acetate-based copolymer resin film layer 4a,
Vinyl acetate content (saponification method) 19% by weight, MFR 2.5g / 10
Min, density 0.94g / cm ³ , EVA resin with Vicat softening point of 64 ℃
60% by weight, an ethylene copolymer resin of ethylene and 4-methylpentene-1 having a density of 0.920 g / cm ³ and an MI of 2.1 g / 1.
It is composed of 38% by weight of L-LDPE resin having a Vicat softening point of 100 ° C. and 2% by weight of carbon black at 0 minutes and has a thickness of 25 μm.

The thermoplastic resin film layer 5a is the same as the product I of the present invention.

 The adhesive layer 3 is the same as the product I of the present invention.

Comparative product I A layer formed to have a thickness of 50 μm with the same resin composition as the ethylene vinyl acetate-based copolymer resin film layer 4a of the invention product IV, and the same resin composition as the thermoplastic resin film layer 5a of the invention product IV. It is a packaging material for a two-layer coextrusion film comprising a layer formed to have a thickness of 50 μm. The light-reflecting flexible sheet layer 1 and the adhesive layer 3 were the same as those of the product IV of the present invention.

In the above invention products, the measuring method of each property was as follows.

Shown in JIS K7206 = ASTM D1525 Experimental Results Table 1; MI (g / 10 min); JIS K6760 = ASTM D1238 ( 190 ℃) Density ^{(g / cm 3); JIS} K6760 = ASTM D1505 Vicat softening point (℃) .

EFFECTS OF THE INVENTION The present invention comprises a light-reflecting flexible sheet layer and a multi-layer coextrusion blocking laminated film layer,
Tear strength, gelbotest strength, burst strength, impact drilling strength, and other physical strengths have been significantly improved, curling hardly occurs, printability, front / back distinction under safelight, and antistatic properties have been improved. Moreover, it is possible to prevent the temperature from rising in the sunlight.

[Brief description of drawings]

1 to 7 are partial cross-sectional views showing the layer structure of an embodiment of the packaging material according to the present invention. 1 ... Light-reflecting flexible sheet layer 2a, 2 ... Multi-layer coextrusion blocking laminated film layer 3a, 3 ... Adhesive layer 4a, 4 ... Ethylene vinyl acetate-based copolymer resin film layer 5a, 5 ... Thermoplastic resin Film layer 6a, 6 …… two-layer coextrusion inflation film 7a, 7 …… intermediate layer 8a, 8 …… three-layer coextrusion inflation film 9a, 9 …… four-layer coextrusion inflation film a; having a light-shielding property Show.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G03C 3/00 580

Claims (2)

[Claims] 1. A pseudo-adhesive layer comprising two layers of ethylene vinyl acetate copolymer resin film layers, which are inner layers of a multilayer coextruded film, adhered by blocking, and a light-reflecting flexible sheet layer. Characteristic packaging material 2. A light-reflecting flexible sheet layer and a multilayer coextrusion blocking laminated film layer having a pseudo adhesive layer in which the inner layers of the multilayer coextrusion inflation film are adhered by blocking, the multilayer coextrusion inflation film comprising: Vinyl acetate content is 5% by weight
A packaging material characterized by having the above-mentioned inner layer ethylene vinyl acetate-based copolymer resin film layer and an outer layer thermoplastic resin film layer containing an antiblocking substance.