JPH07101296B2 - Packaging material for photosensitive materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to packaging of photosensitive materials, particularly various photographic photosensitive materials such as X-ray photographic film, lith film, cut film, photographic paper, PS plate, and photosensitive resin film. The present invention relates to a packaging material suitable for.

[Conventional technology]

In general, as a packaging material for high-tech 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. Has been done.

Heretofore, some proposals have been made to satisfy these properties.

The present inventor has already disclosed what has improved physical strength by combining two layers of uniaxially stretched films in order to improve a packaging material for photosensitive substances (Japanese Patent Laid-Open No. 57-6754).

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. The double-layered uniaxial molecular orientation film is the thickness of the laminated film that is heat-melt-bonded on both sides of the foam with or without the heat-melting adhesive layer so that the molecular orientation axes intersect at an angle of 30 degrees or more. However, a laminated film that has a high impact punching strength and gelbotest strength compressed to a thickness of 40 to 85% of the theoretical sum of each layer (residual thickness ratio) and has a small curl It has already been disclosed (Japanese Patent Laid-Open No. 59-201848).

[Problems to be Solved by the Invention]

However, the packaging material disclosed in JP-A-57-6754 is inferior in heat-sealing property, has low impact punching strength and gelbotest strength, and is easily damaged.

Further, the packaging material described in JP-A-59-201848 has a large thickness and is insufficient in antistatic property for a high-sensitivity photographic light-sensitive material, and a heat seal for securing light-shielding property, moisture-proof property, etc. The suitability was bad. Furthermore, the packaging was not suitable for automatic bag making, and the packaging was very expensive.

The present invention solves the above problems and prevents the occurrence of lumpy uneven failures, fisheyes and blocking while securing impact drilling strength, tear strength, heat sealing suitability, etc., and improves the dispersibility of light-shielding substances. It is an object of the present invention to provide a packaging material for a photosensitive material, which has a high rate and tensile strength and is excellent in film moldability.

[Means for Solving the Problems]

The present invention has been made in order to achieve the above-mentioned object, and is a first linear low density having a large impact punching strength and tear strength, good heat sealability, and excellent dispersibility of a light-shielding substance. Polyethylene resin (hereinafter referred to as L-LDPE)
And a second L-LDPE resin having good compatibility with the first L-LDPE resin, good anti-blocking properties, and high tensile strength, and a packaging material is molded.

That is, the packaging material for a photosensitive material of the present invention has a density (JIS
K6760) is 0.870 to 0.925g / cm ³ , melt flow rate (JI
S K6760) 0.5-7.0g / 10min, Vicat softening point (ASTM D1
525) is the first linear low-density polyethylene resin with a temperature of 105 ° C or less 50-95% by weight, and the density (JIS K6760) is 0.926-0.950g.
/ cm ³ , melt flow rate JIS K6760) 0.5-7.0g / 10
Second, Vicat softening point (ASTM D1525) of 106 ℃ or higher
Of 5 to 50% by weight of a linear low-density polyethylene resin, 0.1 to 15% by weight of a light-shielding substance, and 0.01 to 2% by weight of an antioxidant, a light-shielding linear low-density polyethylene resin film layer. It is configured to have.

The first and second L-LDPE resins used in the present invention are called the third polyethylene resin, and meet the demands of the age of energy saving and resource saving, which have the advantages of both middle and low density polyethylene resins. Low cost, high strength resin. This resin is a copolymer obtained by copolymerizing ethylene and an α-olefin having 3 to 13 carbon atoms, preferably 4 to 10 carbon atoms by a low pressure method or a high pressure improvement method, and is a linear resin having an ethylene content of 85 to 99.5 mol%. It is a low-medium density polyethylene resin with a structure that has short branches in a straight chain.

As the α-olefin, butene-1, octene-1, hexene-1, 4-methylpentene-1, heptene-1,
Etc. are used, and the amount thereof is about 0.5 to 15 mol% of the polymer. Density is generally considered to be low to medium density polyethylene resin, but most commercial products have a density within the range of 0.87 to 0.95 g / cm ³ .

If you show a concrete example of L-LDPE resin by the product name, G resin and TU
FLIN and NUC-FLX (UCC), Dow Rex (Dow Chemical Co.), Sclere (DuPont Canada Co.), Excellen (Sumitomo Chemical), Marlex (Phillips Co.), Neo-Zex and Ulto-Zex (Mitsui Petrochemical), Nisseki Linilex (Nippon Petrochemical), Stamilex (DSM
Company), Idemitsu Polyethylene L and Moretec (Idemitsu Petrochemical), NUC Polyethylene-LL and TUFTHENE (Nippon Unicar), and the like.

A preferred representative example is the product name, in which polyethylene is artificially modified to have 4-C6 as an α-olefin side chain.
Ultozex of Mitsui Petrochemical Co., Ltd. in which methylpentene-1 was introduced, and Stamilex of DSM Co., Ltd. in which octene-1 of 8 carbon atoms was introduced as an α-olefin side chain, and Moatech and Dow of Idemitsu Petrochemical Co., Ltd. There is Dowlex, etc. of Chemical Co. (these are L-LDPE resins obtained by the co-liquid phase process of the four companies).

The first L-LDPE resin has a density of 0.870 to 0.925 g / cm ^3.
Is. When the density is less than 0.870 g / cm ³ , the polymerizability is poor, blocking is likely to occur, and it is expensive and difficult to put into practical use. When the density exceeds 0.925 g / cm ³ , the impact drilling strength is lowered and the tear strength is lowered, and it becomes difficult to achieve the object of the present invention with the resin composition of the present invention used in combination with the second L-LDPE resin. Become.

The density of the first L-LDPE resin is 0.925 g / cm ³
The following copolymers of ethylene and α-olefins having 6 or more carbon atoms, and copolymer resins of ethylene and butene-1 having 4 carbon atoms have a very low density L of 0.910 g / cm ³ or less. -LDPE resins are particularly preferred. Typical examples of commercially available products include Excellen from Sumitomo Chemical Co., Ltd. and NUC-FLX from UCC.

The first L-LDPE resin has an MFR of 0.5 to 7.0 g / 10 minutes. If the MFR is less than 0.5g / 10 minutes, the motor load is large,
Melt fracture easily occurs, which is difficult to put into practical use.
If the MFR exceeds 7.0 g / 10 minutes, drawdown is likely to occur, and the bubble is unstable, making it difficult to put into practical use.

Furthermore, the first L-LDPE resin has a Vicat softening point of 105.
It is below ℃.

When the Vicat softening point exceeds 105 ° C., the resin composition of the present invention is deteriorated in low-temperature heat-sealing property, loses flexibility at low temperature and cold resistance, lowers impact perforation strength, and the object of the present invention cannot be achieved.

The first L-LDPE resin as described above is contained in an amount of 50 to 95% by weight.

If it is less than 50% by weight, impact puncture strength and tear strength are lowered, flexibility at low temperature is lost, and low temperature heat sealability is deteriorated. Further, the receptivity of the light-shielding substance is lowered and the object of the present invention cannot be achieved.

The second L-LDPE resin has a density of 0.926 to 0.950 g / cm ³
Is.

When the density is less than 0.926 g / cm ³ , Young's modulus and tensile strength are lowered, and when a heavy object is put in, it expands and becomes thin, resulting in light shielding and moisture resistance,
If the gas barrier property deteriorates and the density exceeds 0.950 g / cm ³ , not only the polymerizability deteriorates and it becomes expensive, but also the molecules are easily oriented in the vertical direction and the physical strength in the vertical and horizontal directions becomes unbalanced. It is easy for non-uniform failures and fish eyes to occur.

The second L-LDPE resin has an MFR of 0.5 to 7.0 g / 10 minutes. If the MFR is less than 0.5g / 10 minutes, the motor load is large,
Melt fracture easily occurs and it is difficult to put it into practical use. When the MFR exceeds 7.0g / 10 minutes, drawdown is likely to occur, and bubbles become unstable, making it difficult to put it into practical use.

Further, the second L-LDPE resin has a Vicat softening point of 106.
℃ or above.

If the Vicat softening point is less than 106 ° C, the drawbacks of the first L-LDPE resin, such as blocking, low Young's modulus and low tensile strength, cannot be improved, making it difficult to put into practical use.

The second L-LDPE resin as described above is contained in an amount of 5 to 50% by weight.

If it is less than 5% by weight, the drawbacks of the first L-LDPE resin cannot be improved and it is difficult to put it into practical use. If it exceeds 50% by weight, the molecules are easily oriented, and the physical strength balance between the vertical and horizontal directions becomes poor. Not only that, but there are many lumpy non-uniform failures and fish eyes, which makes practical application difficult.

The preferred light-shielding substance used in the present invention is a substance that can be mixed and dispersed in the above L-LDPE resin system, and has a granular, spherical, columnar, scale-like or plate-like shape, which does not transmit visible light, ultraviolet rays and the like. It is a thing.

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, and inorganic pigments.

Among these light-shielding substances, from the viewpoints of quality, cost, light-shielding ability, etc., color pigments that easily absorb or reflect light, especially various carbon blacks of light-absorbing black pigments, light-reflective aluminum powders. It is preferable that the low volatile substance is removed from the aluminum paste.

Especially when carbon black is used, various properties required for packaging materials for photosensitive substances such as antistatic property, physical strength improvement, antioxidation property enhancement, light shielding property improvement, photographic property assurance, heat sealing property improvement and blocking property improvement are improved. This is the most preferable because it can be secured and secured.

And, in terms of securing the light-shielding property, cost and physical strength are preferably average carbon particles of 200 mμ or less furnace carbon black, acetylene carbon black as an expensive light-shielding substance having an antistatic effect, Ketjen carbon black, Graphite and the like are preferable. It is also preferable to mix two or more light-shielding substances according to the required characteristics, if necessary. Even in this case, the average particle size is 200 mμ
Preferred as a packaging material for photographic photosensitive materials that require particularly light-shielding property include the following light-shielding material ² laminated film of 0.5g / m ² ~50g / m. On the other hand, among these carbon blacks, those having a pH of 5 to 9 and an average particle diameter of 10 to 200 mμ are preferable, and furnace carbon black having a pH of 6 to 9 and an average particle diameter of 50 mμ or less is particularly preferable. By using such a pH and particle size, less fog, less increase or decrease in photosensitivity, large light-shielding ability,
To obtain a packaging material having various advantages such as physical strength improvement and heat sealing property in which pinholes due to carbon black lumps and fish eyes are hard to occur even when added to L-LDPE resin film layers, etc. You can

The above light-shielding substance is contained in an amount of 0.1 to 15% by weight.

Typical examples of the antioxidant used in the present invention include phenol-based antioxidants such as n-octadecyl-3 (3 ', 5'-
Di-t-butyl 4'hydroxyphenyl) propinate, 2,6 di-t-butyl 4-methylphenol, 2,6 di-
t-butyl-p-cresol, 2,2'-methylenebis (4-methyl-6-t-butylphenol), 4,4'-
Thiobis (3-methyl 6-t-butylphenol), 4,
4'-butylidene bis (3-methyl-6-t-butylphenol), stearyl-β (3,5-di-4-butyl 4
-Hydroxyphenyl) propionate, 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,
5-di-t-butyl-4-hydroxybenzyl) benzene, octadecyl-3- (3,5-di-t-butyl-4hydroxyphenyl) propionate, tetrakis [methylene-3 (3 ', 5'-di- t-butyl-4'-hydroxyphenyl) propionate] methane and the like.

Examples of sulfur-based compounds include dilauryl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, laurylstearyl thiodipropionate, distearyl-3'-thiodipropionate, ditridecyl- 3,3'-thiodipropionate and the like.

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 lreg
anox 1010, Ireganox 1076, Ionox 330, Topano ICA, etc.), dilauryl thiodipropionate, distearyl thiodipropionate, dialkyl phosphate and the like, and it is effective to use one or more, especially two or more thereof in combination.

The total amount of addition is 0.01 to 2.0% by weight whether used alone or in combination of two or more kinds. 0.01% by weight
If it is less than the above, there is almost no effect of addition. On the other hand, the addition amount is 2.0
When the content exceeds the weight%, the photographic film utilizing the oxidation / reduction effect may be adversely affected and the photographic performance may be abnormal. For this reason, it is preferable to add the antioxidant in a minimum amount that does not cause coloring failure or lumpy non-uniform failure. Particularly preferred are phenolic antioxidants,
Commercially available Ciba Geigy Irganox and Sumitomo Chemical Co., Ltd. Sumilizer BHT, Sumilizer BP-76, Sumili
zer WX-R, Sumilizer BP-101 etc.

Furthermore, when used in combination with carbon black or the like, the antioxidant exhibits a synergistic effect.

A lubricant can be added to the light-shielding L-LDPE resin film layer of the present invention in order to improve film moldability, lubricity, and processability.

The lubricants preferably used in the present invention are fatty acid amide type, alkylamine type, silicone type and fatty acid metal salts.

(1) Oleic acid amide lubricants; Armoslip CP. (Lion Akzo), Neutron (Nippon Seika), Neutron E-18 (Nippon Seika),
Amide O (Nitto Kagaku), Alfuro-E-10 (Nippon Yushi), Diamid O-200 (Nippon Kasei), Diamid G-200 (Nippon Kasei), etc. (2) Erucamide amide lubricant; Alfuro-P- 10 (Nippon Yushi) and others (3) Stearamide amide lubricants; Alflo-S-10 (Nippon Yushi), Neutron 2 (Nippon Seika), Diamid 200 (Nippon Kasei), etc. (4) Bis fatty acid amide lubricants Bis Amide (Nippon Kasei), Diamid 200 bis (Nippon Kasei), Armowax EBS (Lion Akzo)
Etc.

Other alkylamine lubricants include Electrostripper TS-2 and Electrostripper TS-3 (Kao Soap).

Examples of silicone lubricants include various grades of dimethylpolysiloxane and its modified products (Shin-Etsu Silicone, Toray Silicone) and the like.

The preferable additive amount of these lubricants is 0.001 to 1.0% by weight, which does not adversely affect them when used for packaging photographic light-sensitive materials.
Therefore, not only the single addition but also two types may be used in combination.
The preferred fatty acid amide lubricant for the present invention has from 8 carbon atoms.
50 pieces, particularly preferably 15 to 35 pieces. However, in the case of a fatty acid metal salt or the like having a small slipping effect, about 5% by weight can be added and used as a dispersibility improving agent for a light-shielding substance.

Further, in order to prevent blocking of the light-shielding L-LDPE resin film layer, an antiblocking agent can be added. Antiblocking agents are silica, calcium carbonate,
Talc (magnesium silicate), aluminum silicate,
There are calcium silicate, dicarboxylic acid ester amide and the like. Among them, silica is preferable, and the preferable addition amount in the present invention is 0.01 to 5.0% by weight. If it is less than 0.01% by weight, the antiblocking effect is small and only the kneading cost increases. If it exceeds 5.0% by weight, not only lump-shaped non-uniform failures occur, but also the physical strength and heat sealability of the film deteriorate.

This silica preferably has an average particle size of 0.3 to 20 μm. If it is less than 0.3 μm, the cohesiveness is strong and many spots are generated, and the blocking prevention effect is small. 20μ
When it exceeds m, not only the surface of the film becomes silica and the surface of the film becomes rough, but also scratches and the like are likely to occur on the photosensitive material.

In addition, various additives can be added to the light-shielding L-LDPE resin film layer in required amounts, if necessary.

Typical examples of the additives are described below, but the present invention is not limited thereto and can be selected from all known ones.

The packaging material for a photosensitive material of the present invention only needs to have the light-shielding L-LDPE resin film layer, that is, the simplest structure is a single layer of the light-shielding L-LDPE resin film layer. is there. Further, it may be a multi-layer co-extruded film having two or more light-shielding L-LDPE resin film layers, or a multi-layer co-extruded film other than the light-shielding L-LDPE resin film layer. Further, a flexible sheet may be laminated on the light-shielding L-LDPE resin film layer to form a laminated film.

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 their modified resin films. Further, there are a metal thin film processed film (a typical example is an aluminum vacuum deposited film), a cellulose acetate film, cellophane, polyvinyl alcohol, various papers, various metal foils (a typical example is an aluminum foil), and non-woven fabrics. Particularly preferred flexible sheet layers are various papers having a basis weight of 20 to 400 g / m ² (unbleached kraft paper, semi-bleached kraft paper, bleached kraft paper,
Neutral paper, Hinelli base paper, bleached sulfite paper, Clupak paper, Duostress paper, white paperboard, photographic base paper, pure white roll paper, coated paper, imitation paper, glassine paper), thickness 5-50μ
m metal foil (aluminum foil, zinc foil, lead foil, iron foil, etc.), aluminum vacuum-deposited paper, metal processed film (typically aluminum vacuum-deposited thermoplastic resin film), and the like.

For laminating the flexible sheet layer or the like on the L-LDPE resin film layer, various known methods may be used.

The packaging material for a photosensitive substance of the present invention can be used for packaging any photosensitive substance such as a photographic photosensitive material, food, medicine, chemical substance and the like. Especially for photographic light-sensitive materials such as silver halide photographic light-sensitive materials, diazo photographic light-sensitive materials, photosensitive resins, self-developing photographic light-sensitive materials and diffusion transfer photographic light-sensitive materials whose quality is destroyed by slight gas, light and humidity. Optimal.

When the packaging material for a photosensitive substance of the present invention is applied to the above photographic photosensitive material, for example, a single flat bag, a double flat bag, a self-supporting bag, a single gusset bag, a double gusset bag, a single-layer L-LDPE resin film, and a multilayer It can be used in all known forms such as extruded L-LDPE-based resin film, inside a moisture-proof box, inside a light-chamber light-shielding box, and leader paper.

The bag-making method depends on the sealing properties of conventionally known plastic films such as heat seal, fusing seal, impulse seal, ultrasonic seal, and high frequency seal depending on the properties of the light-shielding L-LDPE resin film layer used. In addition, it is also possible to make a bag by using an appropriate adhesive or pressure-sensitive adhesive.

[Action]

In the present invention, the first L-LDPE resin increases impact strength and tear strength, and improves heat sealability,
Furthermore, the dispersibility of the light-shielding substance is improved, and the second L-
LDPE resin improves blocking resistance and increases tensile strength. The light-shielding substance imparts light-shielding properties, improves the physical strength of the L-LDPE resin film layer, and prevents the antioxidant from causing coloring failure in the resin.

〔Example〕

Embodiments of the packaging material for photosensitive material of the present invention are shown in FIGS.
It will be described with reference to the drawings.

1 to 8 are partial cross-sectional views showing the layer structure of a packaging material for a photosensitive substance.

The packaging material for the photosensitive material of FIG. 1 is composed of a single film of the light-shielding L-LDPE resin film layer 1a.

The packaging material for the photosensitive substance shown in FIG. 2 is a light-shielding L-LDPE resin film layer 1a and a thermoplastic resin film layer containing a light-shielding substance.
It is composed of a multilayer coextrusion light-shielding film Ia consisting of two layers 2a.

The packaging material for photosensitive material shown in FIG. 3 has two light-shielding L-LDPEs.
It is composed of a multi-layer coextrusion light-shielding film Ia consisting of three layers in which the intermediate layer 3 is laminated between the resin film layers 1a.

The photosensitive material packaging material of FIG. 4 has three layers in which an intermediate layer 3 containing no light-shielding substance is laminated between a light-shielding L-LDPE resin film layer 1a and a thermoplastic resin film layer 2a containing a light-shielding substance. It is composed of a multilayer coextrusion light-shielding film Ia composed of layers.

The packaging material for the photosensitive material shown in FIG. 5 has a flexible sheet layer 5 with a light-shielding L-LDPE resin film layer 1a through an adhesive layer 4.
Is composed of three layers.

The packaging material for the photosensitive material of FIG. 6 is constituted by directly laminating the heat seal layer 7 on the light-shielding L-LDPE resin film layer 1a.

The packaging material for the photosensitive substance of FIG. 7 is constituted by laminating the flexible sheet layer 5 on the multilayer coextrusion light-shielding film Ia shown in FIG. 2 via the adhesive layer 4.

The packaging material for the photosensitive material shown in FIG. 8 is constituted by laminating the metal foil 6 and the flexible sheet layer 5 on the multilayer coextrusion light-shielding film Ia shown in FIG. 2 via the adhesive layer 4.

Next, the experimental results comparing the characteristics of the present invention products I to IV, the comparative products I to III, and the conventional product I will be described.

Invention Product I The first L-LDPE resin has a density of 0.920 g / cm ³ and an MFR of 2.0 g / cm ³ .
10 minutes, Vicat softening point 93 ℃, ethylene and carbon number 6
L- which is a copolymer resin with 4 pieces of 4-methylpentene-1
LDPE resin (Ultzex; manufactured by Mitsui Petrochemical Co., Ltd.) was used and the amount was 60% by weight.

The second L-LDPE resin has a density of 0.940 g / cm ³ and an MFR of 2.1 g /
10 minutes, Vicat softening point 115 ° C, ethylene and carbon number 6
L- which is a copolymer resin with 4 pieces of 4-methylpentene-1
LDPE resin (Ultzex; manufactured by Mitsui Oil Co., Ltd.) was used and the amount was 36.8% by weight.

Furnace carbon black (# 44B; manufactured by Mitsubishi Kasei Co., Ltd.) having an average particle diameter of 21 mμ and pH of 7.7 was used as the light-shielding substance.
Wt% was added.

As the antioxidant, 0.05 wt% of stearyl-β (3,5-di-4-hydroxyphenyl) propionate, which is a phenolic antioxidant, and tetrakis [methylene-3
(3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane was added at a total of 0.25% by weight, 0.15% by weight.

Invention Product II Same as Invention Product I except that the addition amounts of the first L-LDPE resin and the second L-LDPE resin were reversed.

Invention product III The first L-LDPE resin has a density of 0.920 g / cm ³ and an MFR of 2.3 g / cm ³ .
10 minutes, using L-LDPE resin (Ultzex; manufactured by Mitsui Oil Co., Ltd.), which is a copolymer resin with 4-methylpentene-1 having a Vicat softening point of 97 ° C. and 60 carbon atoms, 60 weight %.

The second L-LDPE resin has a density of 0.935 g / cm ³ and an MFR of 2.1 g /
10 minutes, using L-LDPE resin (Ultzex; manufactured by Mitsui Petrochemical Co., Ltd.), which is a copolymer resin with 4-methylpentene-1 having a Vicat softening point of 113 ° C. and 6 carbon atoms, 3
It was 6.8% by weight.

The light-shielding substance and the antioxidant are the same as those of the product I of the present invention.

Invention product IV The first L-LDPE resin has a density of 0.920 g / cm ³ and an MFR of 2.1 g / cm ³ .
10 minutes, using L-LDPE resin (Ultzex; manufactured by Mitsui Oil Co., Ltd.) which is a copolymer resin with 4-methylpentene-1 having a Vicat softening point of 100 ° C. and 6 carbon atoms, 60% by weight And

The second L-LDPE resin has a density of 0.930 g / cm ³ and an MFR of 2.1 g /
10 minutes, 36.8 wt% using L-LDPE resin (Ultzex; manufactured by Mitsui Oil Co., Ltd.) which is a copolymer resin with 4-methylpentene-1 having a Vicat softening point of 109 ° C. and 6 carbon atoms did.

The light-shielding substance and the antioxidant are the same as those of the product I of the present invention.

Comparative Product I The second L-LDPE resin used in Invention Product I was used at 96.8% by weight.

The light-shielding substance and the antioxidant are the same as those of the product I of the present invention.

Comparative product II 96.8% by weight of the second L-LDPE resin used in the invention product IV was used.

The light-shielding substance and the antioxidant are the same as those of the product I of the present invention.

Comparative product III 96.8% by weight of the first L-LDPE resin used in the invention product I was used.

The light-shielding substance and the antioxidant are the same as those of the product I of the present invention.

Conventional product I Density 0.923g / cm ³ , MFR 2.4g / 10min, Vicat softening point
97% by weight of LDPE resin at 93 ° C. was used.

In the film formation, a ring die having a lip clearance of 1 mm was used to form an inflation film having a thickness of 70 μm at a blow ratio of 1.76.

The experimental results are shown in Table 1.

The evaluation is as follows.

◎… very good ○… excellent ●… possible (within practical limits) ▲… problem (needs improvement) ×… not practical * A anti-blocking property Inflation film made by the above film forming process is wound up. Then, it was cut with a razor to a folding diameter of 330 mm × 220 mm, and it was judged from the ease of opening this cutting opening.

* B peeling belt voltage An endless belt with a width of 35 mm and a length of 1350 mm is made of the film to be tested, and the peeling belt is fed between the SUS roller (stainless steel) with a load of 500 g and the SUS roller at a speed of 12 m / min. Voltmeter (made by Shinto Kagaku KK)
The value measured in.

* C Film formability Motor load (current value), bubble stability, frost line position, fish eye, spots, film wrinkles, film thickness unevenness, etc. when the inflation film of the present invention is formed using an inflation film molding machine. It is evaluated by the suitability for production of total inflation film.

* D Dispersibility of carbon black Evaluation is made based on the light-shielding property when the inflation film containing the carbon black of the present invention is manufactured using an inflation film molding machine, and the degree of occurrence of fish eyes and spots.

* E Bag-making suitability, difference in melting temperature between inner and outer layers, low-temperature heat-sealing property, heat-sealing strength, hot-tacking property, foreign matter sealing property, and heat-sealing strength with time required when creating a sealed bag using the packaging material of the present invention The characteristics of curling, etc. are excellent, pinholes do not occur, it is difficult to break the bag during distribution, and it is evaluated from the ease of manufacturing a packaging bag for photosensitive materials that can be heat-sealed even at low temperatures.

〔The invention's effect〕

The packaging material for a photosensitive material of the present invention is based on a resin that is a blend of two types of L-LDPE resins each having its own characteristics,
Since it uses a light-shielding substance and an antioxidant together, it has excellent physical properties, high tear strength, high impact puncture strength, excellent blocking resistance, and low charge amount.
It has good dispersibility of light-shielding substances, less generation of spots and fish eyes, excellent film moldability, good heat sealability, small change in heat seal strength over time, and excellent bag making suitability.

[Brief description of drawings]

1 to 8 are partial cross-sectional views showing the layer structure of the packaging material for light-shielding substances. 1a: Light-shielding L-LDPE resin film layer 2, 2a: Thermoplastic resin film layer 3, 3a: Intermediate layer 4, 4a: Adhesive layer 5, 5a: Flexible sheet layer 6: Metal foil 7, 7a: Heat seal layer a: Indicates that it contains a light-shielding substance.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location G03C 3/00 560 F

Claims (1)

[Claims] 1. A first linear low-density polyethylene resin having a density of 0.870 to 0.925 g / cm ³ , a melt flow rate of 0.5 to 7.0 g / 10 minutes, and a Vicat softening point of 105 ° C. or less, 50 to 95% by weight.
And the density is 0.926 to 0.950 g / cm ³ , and the melt flow rate is
0.5 to 7.0 g / 10 minutes, 5 to 50% by weight of second linear low-density polyethylene resin having a Vicat softening point of 106 ° C or higher, 0.1 to 15% by weight of light-shielding substance, and 0.01 to 2% of antioxidant. % Of a light-blocking linear low-density polyethylene resin film layer containing