JPH0833620B2 - Packaging materials for photographic photosensitive materials - Google Patents

Description

TECHNICAL FIELD The present invention relates to a packaging material suitable for a photographic light-sensitive material.

[Conventional technology]

Various types of packaging materials for photographic light-sensitive materials have been widely put into practical use, and various performances are required according to the uses thereof.

A packaging material that completely blocks light is used as a packaging material for a photographic light-sensitive material that loses its quality value when exposed to light. In this case, the required properties include packaging material slit suitability, gas barrier properties, light shielding properties, moisture resistance, rigidity, physical strength, (breaking strength, tear strength, impact drilling strength, gelbotest strength, friction strength, etc.) heat seal suitability ( Heat sealing strength, cut sealing property, hot tacking property, foreign substance sealing property, etc.), antistatic property, flatness, and sliding property.

As such a packaging material, a film obtained by adding carbon black to a linear low-density polyethylene (hereinafter referred to as L-LDPE) resin has excellent physical strength and heat sealability, and thus L-LDPE resin of various densities. The present inventor has proposed a packaging material having a layer (JP-A-61-189936,
JP-A-62-18547, etc.).

In addition, it is difficult to combine a single film material having the above-mentioned various properties, and conventionally, a packaging material having a plurality of layers has been used.

[Problems to be solved by the invention]

However, the laminated film having the L-LDPE resin layer may not have sufficient interlaminar peel strength, is difficult to be folded, has large curling, and has poor front / back surface discrimination.

An object of the present invention is to provide a packaging material for a photographic light-sensitive material, which retains the physical properties and heat-sealing properties of the L-LDPE resin film, while solving the problems such as the delamination strength. .

[Means for solving problems]

The present invention has been made to achieve the above object, the melt index is 0.1 ~ 5g / 10 minutes and the density is 0.941g.
Corona discharge treatment is applied to the surface of the high density polyethylene resin film layer of the multi-layer coextrusion film layer having a high density polyethylene resin film layer and a linear low density polyethylene resin film layer that have been subjected to corona discharge treatment of not less than / cm ³ 20 to give a linear low density polyethylene resin which is a copolymer resin of ethylene and an α-olefin having 4 to 8 carbon atoms.
Longitudinal Young's modulus is 60 kg / mm ² through the adhesive layer containing more than wt%
A packaging material for a photographic light-sensitive material is constituted by laminating the above flexible sheet layers, containing a light-shielding substance in any one of the layers, and completely blocking light.

Examples of the flexible sheet layer include various molecular orientation thermoplastic resin films (including longitudinal, lateral and oblique uniaxial molecular orientation and biaxial molecular orientation thermoplastic resin films) such as various polyethylene resins, ethylene copolymer resins, polypropylene resins, poly Vinyl chloride resin, polyvinylidene chloride resin,
Polyamide resin, polycarbonate resin, fluororesin,
Known thermoplastic resin film such as polyester resin,
And films of their modified resins. Also, metal thin film processed film (typically aluminum vacuum deposited film), metal thin film processed paper, cellulose acetate resin film, cellophane, polyvinyl alcohol resin film, various papers, various metal foils (a typical example is aluminum foil). There are well-known flexible sheet layers such as non-woven fabric, warp cloth, and perforated film.

Particularly, a biaxially stretched thermoplastic resin film having a thickness of 6 to 50 μm or an aluminum vacuum-deposited biaxially stretched thermoplastic resin film is preferable.

Also, this flexible sheet layer has a vertical Young's modulus of 60.
It is at least kg / mm ² .

When the Young's modulus is less than 60 kg / mm ² , the film is stretched by applying tension when it is laminated with a multi-layer coextrusion film, and when the tension is released, the film shrinks to reduce the adhesive strength, resulting in delamination, curling and wrinkling.

The high density polyethylene (hereinafter referred to as HDPE) resin film layer has a melt index of 0.1 to 0.5 g / 10 minutes and a density of 0.
It is made of resin of 941 g / cm ³ or more.

When the melt index is less than 0.1 g / 10 minutes, the film formability is poor and the molecular orientation is large in the vertical direction, so that the tear strength in the vertical direction becomes too small and it becomes difficult to practically use.

When the melt index exceeds 5.0 g / 10 minutes, the film moldability is good, but the physical strength is low and it is not practical. Density is
If it is less than 0.941 g / cm ³ , the crystallinity is insufficient, the molecular orientation in the vertical direction is small, and the effect of the present invention cannot be expected.

The resin used for the HDPE-based resin film layer may be a resin formed by only the HDPE resin or a resin obtained by kneading the HDPE resin and another resin as long as the melt index and the density are the above-mentioned values as a whole. As this kneadable resin, a polyolefin resin, for example, a low-density polyethylene resin,
Ethylene copolymer resin (EVE resin, EEA resin, L-LDPE resin,
EMA resin, EAA resin, propylene-ethylene copolymer resin, etc.) are preferable. Particularly, L-LDPE resin which is a copolymer resin of ethylene and α-olefin is preferable.

Further, the HDPE resin film layer is subjected to corona discharge treatment. This corona discharge treatment is performed to improve the adhesiveness, and when the corona discharge is applied to the HDPE resin film layer, the adhesive property is significantly improved as compared with the case where the corona discharge is applied to the L-LDPE resin film layer. is there.

Particularly, when a gas containing ozone is blown, the adhesive strength is further increased, so it is preferable to apply it as necessary. It is also preferable to apply various anchor coat layers, if necessary, to further increase the adhesive strength. The anchor coating agent used in the anchor coating layer includes polyethyleneimine type, alkyl titanate type, polyolefin type, isocyanate type, polyurethane type, polyester type, polybutadiene type and the like.

The L-LDPE resin film layer is formed by including the L-LDPE resin, and this L-LDPE resin is a branched low-density polyethylene resin () produced by a conventional high-pressure process (3000 atm, 300 ° C). It has a narrower molecular weight distribution and is linear compared to LDPE). Since it is an energy-saving process product, it is inexpensive, has good hot tack property and foreign substance sealing property, and is excellent in that it has little decrease in heat seal strength at low temperature and with time, and has good cold resistance.

The L-LDPE resin is preferably contained in an amount of 30% by weight or more, and is composed of ethylene and an α-olefin having 4 to 10 carbon atoms. If the amount of the L-LDPE resin is less than 30% by weight, the hot tack property, the foreign substance sealing property, the heat sealing strength over time, etc. are insufficient, and the physical strength is small, and the effect of the present invention cannot be expected. α-olefin has 3 carbon atoms
If the number is less than the above, the physical strength is still small, and the hot tack property, foreign substance sealing property, heat sealing strength with time, etc. are insufficient, and the effect of the present invention cannot be expected. When the carbon number of the α-olefin becomes 11 or more, a problem occurs in the polymerizability of the resin,
Film formation also becomes difficult.

As the L-LDPE resin, a typical and inexpensive commercially available L-LDPE resin is a copolymer resin of ethylene and butene-1 having 4 carbon atoms, MI of 0.1 to 10 g / 10 minutes, and density. Is 0.87 to 0.935 g / cm ³ .

A typical example is an ethylene copolymer resin developed by Union Carbide Corporation in the United States, which is produced by a low pressure, gas phase reaction in the presence of a highly active catalyst called Unipol process.

As the manufacturing method other than the gas phase method, there are a liquid phase method and a high pressure remodeling method by ionic polymerization.

The specific product name and its manufacturing method are as follows: Gas phase method: G resin (Unipol) (UCC), NCU polyethylene-LL (Nippon Unicar), etc. Liquid phase method: Idemitsu Polyethylene L (Idemitsu Petrochemical), Nisseki Linirex ( Nippon Petrochemical), SCLEAR (DuPont Canada), etc. High-pressure method (ion polymerization) ... Rotorex (CDF chimie) is available.

In addition, as a typical and preferable commercially available L-LDPE resin having a large physical strength, the melt index is 0.5 to 1
4-methylpentene-1 or hexene-1 having 6 carbon atoms or octene-1 having 8 carbon atoms is added to ethylene as an α-olefin having a density of 0.870 to 0.939 g / cm ³ at 0 g / 10 minutes. Some are copolymerized. Examples of L-LDPE resins obtained by copolymerizing ethylene with 4-methylpentene-1 having 6 carbon atoms as an α-olefin include Ultozex manufactured by Mitsui Petrochemical Co., Ltd. and hexene as an α-olefin. -1 and ethylene copolymerized L-LDPE
As the resin, TUFLIN manufactured by Union Carbide
Etc. The L-LDPE resin obtained by copolymerizing octene-1 which is an α-olefin having 8 carbon atoms and ethylene is DSM-STAMI CARBON CORPORATION liquid phase method Stamilex and Dow Chemical company liquid phase method DOW. There are Rex etc.

In order to form a multi-layer co-extrusion film layer by co-extruding the HDPE-based resin film layer and the L-LDPE-based resin film layer, it is not necessary to use a special film forming machine, and an inexpensive conventional multi-layer co-extrusion inflation film forming machine is used. Good.

In addition to the above, examples of resins that can be kneaded into the multilayer coextrusion film layer include the following resins.

(1) Ethylene / butene 1 copolymer resin (2) Propylene / butene 1 copolymer resin (3) Ethylene / propylene / butene 1 terpolymer resin (4) Polybutene-1 resin (5) Polystyrene resin ( 6) Polymethyl / methacrylate resin (7) Styrene / acrylonitrile copolymer resin (8) ABS resin (9) Polypropylene resin (10) Crystalline propylene-α-olefin copolymer resin (11) Modified polypropylene resin (12) Modified Polyethylene resin (13) Polypropylene / maleic anhydride graft copolymer resin (14) Chlorinated polyolefin resin (mainly chlorinated polyethylene resin) (15) Ethylene ionomer resin (copolymer of ethylene and unsaturated acid with metal Cross-linked resin) (16) Poly-4-methylpentene-1 resin (17) Vinyl chloride -Propylene copolymer resin (18) Ethylene / vinyl alcohol resin (19) Cross-linked polyethylene resin (electron beam irradiation cross-linking, chemical cross-linking, etc.) (20) Polyisobutylene resin (21) Ethylene-vinyl chloride copolymer resin (22) ) 1,2-polybutadiene resin (23) branched low-density homopolyethylene resin (24) ethylene copolymer resin, etc. The flexible sheet layer and the HDPE-based resin film layer of the multi-layer coextrusion film layer are bonded by an adhesive layer. By using the HDPE resin film layer as the adhesive surface, the corona discharge treatment effect is improved and the interlayer peel strength is increased. As the adhesive used for this adhesive layer, various polyethylene (LDP
E, L-LDPE, MDPE, HDPE) resins, various polypropylene resins, and other polyolefin-based thermoplastic resin hot-melt adhesives,
Ethylene-propylene copolymer resin, ethylene-vinyl acetate copolymer resin, ethylene-ethyl acrylate copolymer resin and other ethylene copolymer resins, ethylene-acrylic acid copolymer resin, ionomer resin and other thermoplastic resin heat There are melt-type adhesives and other heat-melt type rubber-based adhesives, solution adhesives include wet laminating adhesives, and emulsion-type or latex-type adhesives.
Representative examples of emulsion adhesives are polyvinyl acetate, vinyl acetate-ethylene copolymers, vinyl acetate-acrylic acid ester copolymers, vinyl acetate-maleic acid ester copolymers, acrylic copolymers, ethylene-acrylic acid. There are emulsions such as copolymers. Typical examples of the latex type adhesive include rubber latex such as natural rubber, styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR) and chloroprene rubber (CR). Further, as the adhesive for dry lamination, there are isocyanate adhesives, urethane adhesives and the like. Other known adhesives such as paraffin wax, microcrystalline wax, ethylene-vinyl acetate copolymer resin, ethylene-ethyl acrylate copolymer resin blended hot melt laminate adhesive, pressure-sensitive adhesive, heat-sensitive adhesive, etc. Can be used. More specifically, extruded polyolefin adhesives include various polyethylene resins, polypropylene resins, polybutylene resins, and ethylene copolymer (EVE, EEA, etc.) resins, as well as some L-LDPE resins, such as ethylene. Other monomer (α-olefin)
Copolymers, ionomer resins (ionic copolymers) such as Surlyn from Dupont and Hiramin from Mitsui Polychemical, and Admers (adhesive polymers) from Mitsui Petrochemical Co., Ltd. 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 based on the cost, the adhesive strength, the laminating speed, the total thickness of the laminate, etc. Since it is set, the numerical value is not particularly limited.

Various kinds of additives can be added to each layer of the packaging material for a photographic light-sensitive material of the present invention in necessary amounts, if necessary.

Representative examples of the additives are described below, but the additives are not limited thereto and can be selected from all known substances.

Further, in order to improve film moldability, lubricity, and processability, it is preferable to add a lubricant to each layer.

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

(1) Silicone lubricant; various grades of dimethylpolysiloxane (Shin-Etsu Silicone, Toray Silicone) (2) Oleic acid amide lubricant; Armoslip CP.
(Lion Akzo), Neutron E-18 (Nippon Seika), Amide O (Nitto Kagaku), Alflo E-10 (Nippon Yushi), Diamond Mid O-200 (Nippon Kasei), Diamond Mid G-200 (Japan) Chemical conversion) etc. (3) Esca amide lubricant; Alflo P-10 (NOF CORPORATION) etc. (4) Amine stearate lubricant; Alflo S-10
(Nippon Yushi), Neutron 2 (Nippon Seika), Diamid 200 (Nippon Kasei), etc. (5) Bis fatty acid amide lubricants; Bisamide (Nippon Kasei), Diamid 200 bis (Nippon Kasei), Armowax EBS ( (Lion Akzo) etc. (6) Alkylamine lubricants; Electrostripper TS-2 (Kao Soap) etc. are available.

The amount of these lubricants that do not adversely affect the photographic light-sensitive material is 0.01 to 1.0% by weight.
The fatty acid amide-based lubricants which may be used in combination are preferably 10 to 50 carbon atoms, and particularly preferably 15 to 35 carbon atoms.

A light-shielding substance is added to at least one of the layers to secure the light-shielding property. This light-shielding substance means a substance that can be kneaded or dispersed in each layer and does not transmit visible light, ultraviolet light, and the like. Examples of the light-shielding substance that can be used in the present invention include various carbon blacks, graphite, iron oxide, zinc white, 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, and inorganic pigments.

Among these light-shielding substances, from the viewpoints of quality, cost, light-shielding ability, etc., low volatile substances are removed from color pigments that easily absorb or reflect light, in particular carbon black of black pigments, aluminum powder of silver pigments and aluminum paste. Those obtained are preferred.

As a method of blending these light-shielding substances in each layer, there are a masterbatch coloring method and a compound coloring method which have been often used conventionally. The light-shielding substance is a powder colorant, a paste colorant, a wet colorant, a masterbatch, a dye / pigment, as a usage pattern depending on the resin used, the machine used, the cost, etc.
There are colored pellets.

From the viewpoint of securing the light-shielding property, improving cost and physical strength, furnace carbon black having an average particle size of 200 mμ or less is preferable, and acetylene carbon black and Ketjen carbon are expensive as light-shielding substances having an antistatic effect. Black, graphite and the like are preferable.
If necessary, it is also preferable to mix two or more kinds of light-shielding substances according to the required characteristics. Even in this case, the average particle size is 20
It is preferable as a packaging material for photographic photosensitive materials comprising 0mμ the following shielding materials 0.5g / m ² ~50g / m ² laminated film.
On the other hand, among these carbon blacks, pH (JIS K 62
21) and an average particle size (measured by an electron microscope) of 10 to 120 mμ are preferable, and furnace carbon black having a pH of 6 to 9 and an average particle size of 50 mμ or less is particularly preferable. By using those having such a pH and an average particle size, the fog is less likely to occur, the increase or decrease in the photosensitivity is less likely to occur, the light-shielding ability is great, and the carbon black of the carbon black is added even when added to the L-LDPE resin film layer. It is possible to obtain a packaging material for a photographic light-sensitive material, which has various advantages such as being less likely to cause pinholes due to lumps and fisheyes, improving physical strength, and improving heat sealability.

There are various forms of blending the light-shielding substance into the multi-layer coextrusion film, flexible sheet layer (biaxially stretched thermoplastic resin film, etc.), adhesive layer, etc. as described above, but the masterbatch method reduces costs, prevents workplace pollution, etc. In terms of

Next to carbon black, metal powders preferable as a light-shielding substance will be described. This metal powder is a light-reflecting light-shielding substance that gives a silver-colored, highly valuable appearance and is moisture-proof,
It has excellent properties such as light-shielding properties, antistatic properties, heat resistance under sunlight, and gas barrier properties.

As the metal powder, a material obtained by kneading a substance obtained by removing a low volatile substance from aluminum powder or aluminum paste into a thermoplastic resin is particularly preferable.

The aluminum paste is a paste in the presence of mineral spirits and a small amount of higher fatty acids such as stearic acid or oleic acid when producing aluminum powder by a known method such as a ball mill method, a stamp mill method, or an atomizing method. It was made into a shape. In the present invention, this aluminum paste and polyolefin thermoplastic resin (various polypropylene resins, various polyethylene resins, EVE resin, EEA resin, EAA resin, etc.) are heated and kneaded, and a low volatile substance (mineral spirit with a strong foul odor) is vacuum pumped. Those removed in step 1 are used as aluminum paste compound resin and aluminum paste masterbatch resin.

In particular, it is preferable to use it as an aluminum paste masterbatch resin in order to eliminate adverse effects on a photographic light-sensitive material and an offensive odor, and further to reduce the content of mineral spirits in a multilayer coextrusion film layer to 0.1% by weight or less.
For example, the content of mineral spirits in a masterbatch resin with an aluminum paste content of 40% by weight is 1.0% by weight.
However, if the aluminum paste concentration in the multi-layer coextrusion film layer is set to 2% by weight, 19 parts by weight of the natural resin is kneaded with 1 part by weight of the aluminum paste masterbatch. In the coextruded film layer, the mineral spirit is partially removed as a gas during the film forming, so that the mineral spirit content is 0.05% by weight or less. As a result, the photographic light-sensitive material is not adversely affected and the bad odor is reduced.

In addition to aluminum powder, in addition to powdered molten aluminum by atomizing method, granulating method, rotary disc dropping method, evaporation method, etc., aluminum foil is crushed by ball mill method, stamp mill method or the like into flakes. Including things. Since the aluminum powder alone is unstable, various known treatments for inactivating the surface of the aluminum powder are performed.

The packaging material for a photographic light-sensitive material of the present invention is used as a photographic light-sensitive material. In particular, silver halide photographic light-sensitive material, heat-developable color photographic paper, diazo photographic light-sensitive material, photosensitive resin, self-developing photographic light-sensitive material, diffusion transfer photographic light-sensitive material whose quality is destroyed by slight gas, light and temperature. Most suitable for photographic light-sensitive materials.

When the packaging material for a photographic light-sensitive material of the present invention is applied to the above-mentioned photographic light-sensitive material, for example, a single flat bag, a double flat bag, a self-supporting bag, a single gusset bag, a double gusset bag, and a moistureproof box, It can be used in any known form such as inside a light-shielded light-shielding box or 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. In addition, it is also possible to make a bag by using an appropriate adhesive or pressure-sensitive adhesive.

[Action]

In the packaging material for a photographic light-sensitive material of the present invention, the HDPE-based resin film layer improves the corona discharge treatment effect to increase the interlaminar peel strength, and also increases the Young's modulus to prevent curling. The L-LDPE resin film layer secures the hot tack property, foreign substance seal property, low temperature heat seal property, heat seal strength, and heat seal strength over time, which is lacking in the HDPE resin film layer, and expands the allowable heat seal temperature range. are doing. In addition, it covers the drawbacks of the HDPE resin film layer by increasing the allowable amount of carbon black kneading and improving the light-shielding property, tear strength, impact puncture strength, etc. Ethylene and α with 4 to 8 carbon atoms
-The adhesive layer containing 20% by weight or more of a linear low-density polyethylene resin which is a copolymer resin with olefin makes it inexpensive and excellent in laminating suitability.

[Example] An example of the packaging material for a photographic light-sensitive material of the present invention will be described with reference to FIGS. 1 to 5. The present invention is not limited to these examples.

1 to 4 are partial cross-sectional views showing the layer structure of the packaging material for photographic light-sensitive materials.

The packaging material shown in FIG. 1 comprises a flexible sheet layer 1, a multilayer co-extruded film layer 4a comprising an HDPE resin film layer 2a containing a light-shielding substance and an L-LDPE resin film layer 3a containing a light-shielding substance, and an adhesive layer 5 It is a laminated film in which the L-LDPE resin film layer 3a is laminated so as to be inside.

The packaging material of FIG. 2 is composed of an aluminum vacuum-deposited biaxially stretched polyester film layer composed of a biaxially stretched polyester film layer 7 having an aluminum vacuum deposited film layer 6 formed as a flexible sheet layer 1, It is the same as the packaging material in Figure 1.

The packaging material of FIG. 3 is the same as the packaging material of FIG. 1 except that the metal foil 8 is provided between the flexible sheet layer 1 and the multilayer coextrusion film layer 4a.

The packaging material of FIG. 4 is the same as the packaging material of FIG. 2 except that the multilayer coextruded film layer 4a is formed by a three-layer coextruded film obtained by coextruding the intermediate film layer 9.

The packaging material shown in FIG. 5 is a HD containing a light-shielding substance on the outer side of the biaxially stretched polyester film layer 7 in the flexible sheet layer 1 of the packaging material of the present invention shown in FIG.
Multi-layer coextrusion film layer 4a consisting of PE-based resin film layer 2a and L-LDPE-based resin film layer 3a containing a light-shielding substance
Is laminated so that the HDPE resin film layer 2a is on the outside.

The corona discharge treatment condition is about 0 between the aluminum discharge electrode and the surface of the metal roll covered with silicon rubber.
Corona discharge treatment with a voltage of 110 V, a current of 7.5 A and a treatment power of 825 W was performed at intervals of 5 mm, and laminated with the flexible sheet layer 1 via the adhesive layer 5 at a speed of 80 m / min.

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

The flexible sheet layer 1 is a vacuum-deposited aluminum biaxially stretched polyester film having a Young's modulus of 470 kg / mm ² , and the biaxially stretched polyester film layer 7 has a thickness of 12 μm.
Thus, the aluminum vacuum deposition film layer 6 has a thickness of 400Å. H
The DPE resin film layer 2a has an MI of 0.4 g / 10 minutes and a density of 0.94.
Consists of 92.5% by weight of 6g / m ³ HDPE resin, 3% by weight of furnace carbon black with an average particle size of 21mμ and 4.5% by weight of LDPE resin with a MI of 2.4g / 10 minutes and a density of 0.923g / m ^3. 40μ
m. MI of the L-LDPE resin film layer 3a is 2.1 g / 1
0 minutes, 97% by weight of L-LDPE resin which is a 4-methylpentene-1 copolymer resin with ethylene having a density of 0.920 g / cm ³ , and 3% by weight of furnace carbon black having an average particle diameter of 21 mμ.
And has a thickness of 40 μm. A two-layer coextrusion film layer 4a was prepared by these (total thickness 80 μm), and the flexible sheet layer 1 was laminated on the HDPE resin film layer 2a side via the adhesive layer 5 (the adhesive layer 5 is composed of ethylene and butene-1). It is composed of 70% by weight of L-LDPE resin which is a copolymer resin and 30% by weight of LDPE resin, and has a thickness of 13 μm).

Inventive product II Inventive product II has an HDPE resin film 2a with a MI of 1.1 g / 10
Min, density 70% HDPE resin 0.954g / cm ³ and ethylene 4
-Methylpentene-1 copolymer resin with MI of 2.1 g / 1
22.5% by weight of L-LDPE resin with a density of 0.920 g / cm ^{3 in} 0 minutes, M
4.5% by weight of LDPE resin with an I of 2.4 g / 10 min and a density of 0.923 g / cm ^3.
And furnace carbon black 3 with an average particle size of 21 mμ
Inventive product I except that the thickness is 40 μm.
Is the same as

Conventional Product I Instead of the multilayer coextrusion film layer 4a of the Invention Product I,
97% by weight of LDPE resin with MI of 2.4 g / 10 min and density of 0.923 g / cm ^3.
And furnace carbon black 3 with an average particle size of 21 mμ
It is the same as the product I of the present invention, except that an LDPE resin film having a thickness of 80% and a thickness of 80 μm is used.

Conventional product II Instead of the multilayer coextrusion film layer 4a of the invention product I,
97% by weight of L-LDPE resin, which is a 4-methylpentene-1 copolymer resin with ethylene having an MI of 2.1 g / 10 minutes and a density of 0.920 g / cm ³ , and 3% by weight of furnace carbon black having an average particle diameter of 21 mμ. And is the same as the product I of the present invention, except that an L-LDPE resin film layer having a thickness of 80 μm was used.

Comparative product I Same as the product I of the present invention except that the corona discharge treatment was not performed.

Comparative product II The multilayer co-extruded film layer 4a of the invention product I was laminated with the front and back reversed, that is, the L-LDPE resin film layer 3a was placed on the adhesive layer 5 side subjected to corona discharge treatment, and the HDPE resin film layer 2a was used.
Is the same as the product I of the present invention, except that the inside is heat-sealed.

 The experimental results are shown in Table 1.

The evaluation is as follows.

◎… very good ○… excellent ●… possible (within practical limits) ▲… problems need improvement ×… not practical A foldable resin film made by multi-layer coextrusion inflation film molding method of 10cm × 10cm Judgment based on the return angle immediately after being cut into a square and bent diagonally into a triangle B Curling Judgment based on the curling condition that occurs when a packaging material with a width of 80 cm and a length of 1 m is laid vertically (judging from suitability for processing machine) C Front / Back Distinction under Safe Light Judgment is made based on whether the front and back of the laminated film can be easily or easily distinguished under a safety light (safe light) (here red light) that does not cause optical fog on the photographic material D Delamination strength Evaluated by the area of the adhesion trace when delamination is performed in the adhesive layer portion E Young's modulus: According to ASTM D-882.

F Wrinkles and streaks Judgment of the difficulty of generating wrinkles and streaks by the tension during lamination G Tear strength: In accordance with JIS P 8116.

H Heat-sealability Judged from total heat-seal suitability such as heat-seal strength, hot-tack property, contaminant sealability, heat-seal strength over time, allowable temperature range for heat-seal.

〔The invention's effect〕

Since the present invention is configured as described above, the delamination strength is large, the curling is small, the folding is good, the physical strength such as tear strength is large, and the heat sealability and the like can be sufficiently secured.

[Brief description of drawings]

1 to 5 are partial cross-sectional views showing the layer structure of an embodiment of a packaging material for a photographic light-sensitive material according to the present invention. 1,1a …… Flexible sheet layer 2,2a …… HDPE resin film layer 3,3a …… L-LDPE resin film layer 4,4a …… Multilayer coextrusion film layer 5,5a …… Adhesive layer a …… Indicates that it contains light-shielding substances

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location G03C 3/00 560 Q 565 FAW

Claims (1)

[Claims] 1. A multi-layer coextrusion film layer having a high density polyethylene resin film layer having a melt index of 0.1 to 5 g / 10 minutes and a density of 0.941 g / cm ³ or more and a linear low density polyethylene resin film layer. Corona discharge treatment is applied to the surface of the high-density polyethylene resin film layer, and the linear low-density polyethylene resin, which is a copolymer resin of ethylene and α-olefin having 4 to 8 carbon atoms, is contained in an amount of 20% by weight or more. A photosensitizer characterized by laminating flexible sheet layers having a vertical Young's modulus of 60 kg / mm ² or more through an adhesive layer, and containing a light-shielding substance in either layer to completely block light. Packaging material