JPH0833622B2 - Packaging material for photosensitive materials - Google Patents

Description

TECHNICAL FIELD The present invention relates to a packaging material for a photosensitive substance, and particularly to a packaging material for a photosensitive substance which has good physical strength, light-shielding property, and heat-sealing property even with a single layer film. is there.

[Conventional technology]

For photosensitive materials, such as those that lose their quality value when exposed to light, packaging bags that completely block light are used. In addition to the above light-shielding property, this packaging bag has sufficient physical strength according to the size and weight of the photosensitive material, that is, tensile strength,
Tear strength, impact drilling strength, etc. are required, and further heat sealing suitability is required in order to seal the opening by heat sealing. Further, blocking resistance (opening property) and slipperiness are required for inserting the photosensitive material into the packaging bag.

Further, antistatic property is also required to prevent electrostatic charge due to friction between the photosensitive material and the packaging bag.

Conventionally, as a packaging material used for such a packaging bag, a high-pressure branched low-density polyethylene (hereinafter referred to as LDPE) resin film containing carbon black, an aluminum foil, and bleached kraft paper are LDPE resin melt-extruded adhesives. Some were sequentially stacked.

Further, the present inventor, as a packaging material for a roll-shaped photosensitive material or a sheet-shaped photosensitive material of 1 kg or more (particularly a sealed light-shielding bag),
Uniaxially stretched high-density polyethylene with high physical strength (hereinafter HD
We have proposed a laminated film in which a LDPE resin film containing at least one of a light-shielding substance and an antistatic agent is laminated on a cross-laminated film using a resin film (denoted as PE) (Japanese Utility Model Publication No. 56-19087).

Furthermore, a packaging material having an inexpensive cross-laminated film with improved heat-sealing property and light-shielding property was also proposed (Japanese Utility Model Publication No. Sho 61-20590).

Furthermore, as a packaging material using a metal vapor deposition film, 50% by weight or more of L-LD is provided on both sides of the metal vapor deposition film.
A packaging material for a light-sensitive material was proposed in which an L-LDPE resin-based polymer layer containing a PE resin and 0.3 to 30% by weight of a light-shielding substance was laminated on one side or both sides (JP-A-61-54934).

Moreover, it is difficult to use a packaging material made of a single-layer film for a packaging bag that requires various characteristics such as a light-shielding bag of a photographic light-sensitive material. Therefore, as a packaging material made of a single-layer film, it has low photosensitivity, is lightweight, and is used only as a packaging bag for a photographic photosensitive material using a protective backing paper or a lightweight diazo printing paper, for example, as shown in FIG. LDPE resin film 7a with carbon black added
And L-LD with carbon black added
Some were made of PE resin film.

[Problems to be Solved by the Invention]

A conventional laminated film having an LDPE resin film has a large thickness and a large rigidity, so that the packaging workability is poor, and even though the thickness is large, the physical strength (tear strength, etc.) is small, the curling is large, and the cost is high. Therefore, the heat sealability is poor, and dust is generated during packaging work and transportation, holes are formed, tears, and the heat seal part is peeled off, so it is possible to secure light shielding property, moisture resistance and gas barrier property. It was difficult.

Further, the packaging material having the cross-laminated film proposed in Japanese Utility Model Publication No. 56-19087 and Japanese Utility Model Publication No. 61-20590 can significantly improve physical strength such as tear strength and tensile strength. It is excellent as a packaging material and has been put to practical use until recently. However, since the uniaxially stretched high density polyethylene resin film is used for the heat seal layer, the rigidity is high, the packaging workability is poor and the heat seal suitability is poor, and the thickness of the adhesive layer and the stretching ratio of the uniaxially stretched high density polyethylene resin film are Curling and changes in physical strength occurred due to variations, and sometimes peeled off or broke.

Further, a cross-laminated film obtained by laminating a longitudinally uniaxially stretched film and a transversely uniaxially stretched film so that the stretching axes intersect each other is an expensive laminated film because two types of film forming machines are used.

The packaging material proposed in Japanese Patent Laid-Open No. 61-54934 has improved physical strength such as tear strength, but a packaging material in which an L-LDPE resin-based film containing a light-shielding substance is laminated only on one side of a metal vapor deposition film. Curling was large. Also, when L-LDPE resin-based films with almost the same melting point are laminated on both sides, unless the heat seal device is subjected to special processing, the outer layer is melted and destroyed, causing pinholes and strength deterioration. Not only did it wake up, but it also had a bad appearance.

For this reason, it has been put to practical use as a laminated film in which aluminum vacuum-deposited nylon resin film and aluminum vacuum-deposited polyester resin film having a large Young's modulus and heat resistance are laminated, but the curling is very large and these nylon resin films, etc. Was expensive.

For single layer film, LD containing thick carbon black
Since the PE resin film has low physical strength and poor heat-sealing property and it is difficult to completely seal it, it was difficult to secure 100% quality of the photosensitive material.

Further, a packaging material having a single-layer light-shielding film using a resin composition prepared by adding carbon black to L-LDPE resin, which is proposed in JP-A-61-189936 and JP-A-62-18547, is inexpensive. It has good suitability for heat-sealing, and has excellent tear strength and impact puncture strength, making it an excellent packaging material for photosensitive materials.

However, when packaging heavy products, since the Young's modulus is small, holes and tears do not occur in the L-LDPE resin light-shielding film, but it may be stretched and thinned and light-shielding and moisture-proofing properties may not be sufficiently secured. . Further, in the blown film molding method, blocking was likely to occur in a film using an L-LDPE resin having a density of 0.925 g / cm ³ or less.
A film using an L-LDPE resin having a density of 0.925 g / cm ³ or more may have insufficient pinhole resistance and tear strength at low temperatures.

The present invention solves the above problems, all physical strength is excellent, no blocking occurs, heat sealing properties are very excellent, pinhole resistance and tear strength are excellent even at low temperatures, and a non-uniform mass. An object of the present invention is to provide a packaging material for a photosensitive substance, which can secure 100% of the quality of the photosensitive substance using a polyolefin resin light-shielding film with less generation of (bugs).

[Means for solving the problem]

The present invention has been made in order to achieve the above object, and is solved by using a combination of L-LDPE resins of a type having a specific resin composition.

That is, the packaging material for a photosensitive material of the present invention has a melt index of 0.6 to 15 g / 10 minutes and a density of 0.925 to 0.945 g / c.
m ³ and the first linear low-density polyethylene resin with an Orzens rigidity of 3500 Kg / cm ² or more 10 to 90% by weight, a melt index of 0.3 to 20 g / 10 minutes, and a second density of 0.870 to 0.915 g / cm ³ . 5 to 89% by weight of linear low-density polyethylene resin, 0.1 to 20% by weight of carbon black, fatty acid and / or fatty acid compound
It is characterized by comprising a polyolefin resin light-shielding film containing at least 5 components of 0.01 to 5% by weight and an antioxidant of 0.01 to 2% by weight.

The first L-LDPE resin that constitutes the polyolefin resin light-shielding film is MI (JIS K-6760, temperature 190 ° C, load 2.1).
Measured under standard conditions of 6 kgf from 0.6 to 15 g / 10 min, density (JIS K-
6760) is 0.925 to 0.945 g / cm ³ and Olsen rigidity (JIS K-71
06) is 3500 Kg / cm ² or more, and 10 to 90% by weight is contained.

When the content of the first L-LDPE resin is less than 10% by weight, the disadvantages of the L-LDPE resin, such as low Young's modulus, low tensile strength, blocking and lack of lubricity, cannot be improved, and the cost of the blend increases. It is injured. Further, the film moldability is poor (occurrence of drawdown, lack of bubble stability, etc.), and even if the film can be molded, the light-shielding bag lacks suitability for bag making due to blocking or short stretch due to lack of tensile strength, which makes practical application difficult.

On the other hand, if it exceeds 90% by weight, the tear strength in the lateral direction becomes small, the balance of the tear strength in the vertical and horizontal directions is deteriorated, and the bag is easily broken. Contrary to the case of the present invention, addition of carbon black deteriorates various physical properties and heat seal suitability.

In addition, the occurrence of non-uniform lumps increases, which not only deteriorates the appearance but also adversely affects the photosensitive material.

When the MI is less than 0.6 g / 10 min, the film formability is poor, and the molecules are easily oriented in the longitudinal direction to a large extent, and it is difficult to obtain a film having a good balance of physical strength in the longitudinal and transverse directions. In addition, non-uniform lumps (shots) frequently occur and the photosensitive material is easily damaged.

If the MI exceeds 15g / 10 minutes, drawdown and bubble fluctuations occur, making film forming difficult.

From the viewpoint of physical strength, appearance, film moldability, etc. of the film, MI is preferably in the range of 1.0 to 5.0 g / 10 minutes.

If the density is less than 0.925 g / cm ³ , the defects of the second L-LDPE resin cannot be covered. For example, blocking is likely to occur, Young's modulus and tensile strength are reduced, and in a monolayer film, when tension is applied, the film is stretched and thinned, and it becomes impossible to secure light-shielding properties and moisture-proof properties.

If the density exceeds 0.945 g / cm ³ , the molecules are likely to be oriented, the difference between the tear strengths in the vertical and horizontal directions becomes large, the suitability for heat sealing is deteriorated, and nonuniform lumps (pimples) are frequently generated.

The density is preferably in the range of 0.930 to 0.942 g / cm ³ .

If the Olsen rigidity is less than 3500 Kg / cm ² , the film moldability deteriorates. In addition, Young's modulus and tensile strength become small, and when a single-layer film is applied with tension, it is stretched and thinned, and it becomes impossible to secure light-shielding property and moisture-proof property.

The second L-LDPE resin that constitutes the polyolefin resin light-shielding film has an MI of 0.3 to 20 g / 10 minutes and a density of 0.87 to 0.9.
15 g / cm ³ and contained 5-89% by weight.

If it is less than 5% by weight, the effect of improving the pinhole resistance, the low temperature heat sealability and the tear strength is small, and the cost is increased by the blending cost.

If it is used in an amount of more than 89% by weight, the film moldability is deteriorated and blocking is likely to occur. In addition, Young's modulus and tensile strength become small, and when a single-layer film is applied with tension, it is stretched and thinned, and it becomes impossible to secure light-shielding property and moisture-proof property.

If the MI is less than 0.3g / 10 minutes, the motor load will increase,
Melt fracture tends to occur, making it difficult to put into practical use. In addition, the molecules are easily oriented in the vertical direction.

If the MI exceeds 20 g / 10 minutes, blocking easily occurs, the bubbles become unstable, and film formation becomes difficult.

When the density is less than 0.87 g / cm ³ , not only the resin becomes expensive, but also blocking easily occurs, the bubbles become unstable, and film formation becomes difficult.

If the density exceeds 0.915 g / cm ³ , the drawbacks of the first L-LDPE resin cannot be covered, and a polyolefin resin light-shielding film having excellent low temperature heat sealability, pinhole resistance, and tear strength cannot be obtained. In addition, the pinhole resistance and tear strength at low temperatures are reduced.

The L-LDPE resin forming the first L-LDPE resin and the second L-LDPE resin is an ethylene / α-olefin copolymer resin that is inexpensive and has a large physical strength (especially when a light-shielding substance is added). There is a third polyethylene resin,
It is a low-cost, high-strength resin that meets the demands of the times of energy saving and resource saving, which have the advantages of both medium- and low-pressure polyethylene resins.

This L-LDPE 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 has a linear straight chain and short branching. It is a low-to-medium density polyethylene-based resin with a different structure.

As the α-olefin, butene-1, octene-1,
Hexene-1,4-methylpentene-1, heptene-
1, etc. are used, and the density is generally low and about the medium density polyethylene resin, but 0.87 to 0.95 g / cm for commercial products
^Many are within the range of ³ .

Specific examples of L-LDPE resins are G resin, TUFLIN and NUC-FLX (UCC), Dourex (Dow Chemical), Sclear (Dupont Canada), Marlex (Philips), NUC. Polyethylene-LL and T
UFTHENE (Nippon Unicar), Neo-Zex and Ultox (Mitsui Petrochemical), Excellen VL (Sumitomo Chemical), Nisseki Linilex (Nippon Petrochemical), Idemitsu Polyethylene-
L and MORETEC, Idemitsu Petrochemical, Mitsubishi Polyethylene-LL
(Mitsubishi Yuka), Stamirex (DSM) and the like.

Among these L-LDPE resins, from the viewpoint of physical strength and suitability for polymerization, particularly preferable is melt index (hereinafter referred to as MI) of 0.3 to 20 g / 10 minutes (JIS K 6760 temperature 190 ° C, load
2.16kgf standard condition), density 0.870-0.945g / cm ³
(JIS K6760), and α-olefin carbon number 4 to 13
It was obtained by a liquid phase method or a vapor phase method process.

A particularly preferred representative example is the trade name of Ultzex and α-olefin side chain of Mitsui Petrochemical Co., Ltd. in which 4-methylpentene-1 having 6 carbon atoms is introduced into ethylene as an α-olefin side chain. Stamilex of DSM and Dowlex of Dow Chemical Co., Ltd. and MORETEC of Idemitsu Petrochemical Co., Ltd. which introduced octene-1 having 8 carbon atoms as
Etc. (above 4 products manufactured by co-liquid phase method L-
LDPE resin. ).

Carbon black, which is one of the components that make up the polyolefin resin light-shielding film, not only imparts light-shielding properties, but when it is included in the L-LDPE resin of the present invention, it not only improves tear strength, impact perforation strength, and heat-sealing suitability. It is the most important substance that plays many roles such as preventing the formation of spots by preventing the oxidation of resin, preventing blocking, improving lubricity, and adsorbing harmful substances (such as redox substances and metals).

 Carbon black is contained in an amount of 0.1 to 20% by weight.

If it is less than 0.1% by weight, the effect of adding carbon black (securing of light-shielding property, improvement of tear strength, prevention of static electricity, etc.) cannot be expected, and the cost will be increased by the kneading cost.

If it exceeds 20.0% by weight, the physical strength of the film, particularly the tear strength and the impact puncture strength, will deteriorate, and the heat sealability will deteriorate. In addition, the photosensitive material is often contaminated by carbon black on the surface of the film, or the carbon black is often detached from the film and attached to the photosensitive material.

Carbon black is classified into gas black, furnace black, anthracene black, acetylene black, channel black, oil smoke, pine smoke, animal black, thermal black, lamp black, vegetable black, etc. depending on the raw material.

Among these carbon blacks, pH (measured by JIS K6221) 5-9, average particle size (measured by electron microscopy) 10-
A furnace carbon black having a pH of 6 to 9 and an average particle size of 50 mμ or less does not adversely affect the photographic light-sensitive material, is inexpensive, has a large light-shielding ability, and is excellent in kneading dispersibility. preferable. In some cases, it is preferable to use acetylene black, Ketjen carbon black, or graphite, which is expensive but has an excellent antistatic effect.

By using carbon black with such a pH and particle size, fogging is less likely to occur, increase or decrease in photosensitivity is less likely to occur, light-shielding ability is great, and pinholes due to carbon black lumps or fish eyes are generated. It is possible to obtain a light-shielding film that has various advantages such as less occurrence of heat generation, improved physical strength, and improved heat seal suitability.

The above-mentioned various carbon blacks may be used alone or in combination of two or more kinds, and the conductivity may be improved by using metal fibers, carbon fibers, metal powder powder, antistatic agents such as various surfactants and conductive materials in combination. Is preferable because it can

The form in which carbon black is blended with a resin can be various known forms such as colored pellets, die color granules, liquid (liquid) color, dry color, and master batch, but the master batch and die color granules are cost-reduced. It is preferable in terms of preventing contamination of the workplace.

The fatty acid and the fatty acid compound, which are one of the components constituting the polyolefin resin light-shielding film, are used alone or in combination.

Fatty acids and fatty acid compounds are used in addition to neutralizing and detoxifying effects of halides and the like that have a harmful effect on photosensitive substances by polymerization catalysts, in addition to preventing blocking, improving dispersibility of carbon black, improving lubricity, improving film moldability, and Play a role of improving bag suitability. When fatty acids and fatty acid compounds are added to HDPE resins and LDPE resins, heat sealability deteriorates due to bleed-out over time.
By using 5 to 89% by weight of LDPE resin, this is prevented and the heat sealing suitability is made extremely excellent.

The fatty acid and / or fatty acid compound is used in an amount of 0.01 to 5% by weight. If it is less than 0.01% by weight, the effect of addition is not exhibited. If it exceeds 5% by weight, screw slip causes a large variation in the amount of resin discharged, which not only deteriorates the film formability but also results in a film having a large variation in thickness. .

Representative fatty acids include saturated and unsaturated fatty acids such as oleic acid, stearic acid, lauric acid, ricinoleic acid, naphthenic acid, octylic acid, phthalic acid, adipic acid, sebacic acid, acetylricinoleic acid, and maleic acid. .

Further, typical fatty acid compounds include oleic acid amide, erucic acid amide, stearic acid amide, bis fatty acid amide, magnesium stearate, calcium stearate, zinc stearate, aluminum stearate, barium stearate, calcium laurate, octyl acid. Examples include zinc, butyl oleate, and butyl stearate.

An antioxidant, which is one of the components that make up a polyolefin resin light-shielding film, reduces the occurrence of lumps (foreign matter-like solidification) due to resin oxidation during long-term continuous film molding, and when used as a light-shielding bag. Prevents the occurrence of push scratches, scratches, pressure fog, etc. When large spots are generated, heat seal failure occurs in addition to the above-mentioned failure, and it becomes impossible to secure the light-shielding property, the moisture-proof property and the gas barrier property, and the quality of the photosensitive material cannot be ensured.

The antioxidant is not limited to one type, and two or more types may be used in combination. In some cases, the combined use improves the antioxidant effect. For example, a phenol-based antioxidant and a phosphorus-based antioxidant are used in combination, and a volatile antioxidant and a heat-resistant antioxidant are used in combination. In addition, the combined use of the antioxidant effect of carbon black exerts a synergistic effect of antioxidant.

 This antioxidant is used in an amount of 0.01 to 2.0% by weight.

If it is less than 0.01% by weight, the effect of addition is hardly exhibited, and the cost is increased by the kneading cost.

If it exceeds 2.0% by weight, the photographic performance of the photographic light-sensitive material utilizing the oxidation and reduction action will be abnormal.

Even within this addition amount range, it is preferable to select a phenolic antioxidant as a main component in terms of quality assurance.

As antioxidants usable in the present invention, pages 794 to 799 of the Plastic Handbook (published by the KK Industrial Research Association), pages 327 to 329 of the plastic additive data collection (published by KK Chemical Industry Co., Ltd.), PLASTICS AGE ENCYCLOPEDIA Advanced Edition 211-212 of 1986 (issued by KK Plastics Age)
There are various antioxidants disclosed on the page.

Of these known antioxidants, typical examples of the antioxidants that are preferably added to the packaging material of the present invention are shown below, but it goes without saying that they are not limited to these.

Phenolic n-octadecyl-3 (3 ', 5'-di-t-butyl 4'hydroxyphenyl) propionate, 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-methyl6-t-butylphenol), 4,4'-butylidenebis (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, etc.Sulfur-based dilauryl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, laurylstearyl thiodipropionate, distearyl-3'-thiodipropionate , Ditridecyl-3,3'-thiodipropionate, etc. Phosphorus-based trinonylphenyl phosphite, triphenyl phosphite, etc. Especially 2,6-di-t-butyl-p-cresol (BHT) and low volatility Molecular weight phenolic antioxidant (trade name
1reganox1010,1reganox1076, TopanoI CA, Ionox330 etc.)
It is effective to use one or more, especially two or more, of dilauryl thiodipropionate, distearyl thiodipropionate and dialkyl phosphate.

Various thermoplastic resins can be added to the polyolefin resin light-shielding film used in the present invention.
For example, LDPE resin and MDPE which are various polyolefin resins
Resin, polypropylene resin, propylene-ethylene copolymer resin, EVA resin, EMA resin, EEA resin, EAA resin, ionomer resin, ethylene-unsaturated carboxylic acid copolymer resin, ethylene-unsaturated carboxylic acid ester copolymer resin , Various ethylene / alkyl ester copolymer resins, various elastomers, and the like.

The polyolefin resin light-shielding film used in the present invention,
Blocking can be completely prevented without the addition of an antiblocking agent, but the density in the second L-LDPE resin is especially improved to improve tear strength, impact puncture strength and low temperature physical strength.
Various antiblocking agents may be added for applications such as guaranteeing complete prevention of blocking even when the ultra low density L-LDPE resin of 0.0910 g / cm ³ or less is contained in an amount of 50% by weight or more.

Typical antiblocking agents include silica, diatomaceous earth,
Examples thereof include calcium silicate, aluminum silicate, talc, magnesium silicate, calcium carbonate, higher fatty acid polyvinyl ester, n-octadecyl urea and dicarboxylic acid ester amide.

Further, various additives may be added within the range of satisfying the characteristics of the polyolefin resin light-shielding film of the present invention.

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 may be used as a single-layer film, or may be used as a laminated film which is laminated with another flexible sheet and has further excellent properties.

In the lamination, other known materials and other known adhesive layers, anchor coat layers, combinations with flexible sheets, and known surface activation treatments (corona discharge treatment, ultraviolet irradiation treatment, ozone treatment, flame treatment, glow treatment) Discharge treatment, etc.) can be used.

The packaging material for a photosensitive substance of the present invention exerts a great effect only when an inflation film is used.

The package of the present invention, which is flexible and has a large physical strength, has a large physical strength, and uses a blown cylindrical film having a small amount of static electricity, is preferable because the cost can be greatly reduced and the quality can be completely secured.

The photosensitive material packaging material of the present invention is suitable for packaging various photosensitive materials such as photographic photosensitive materials, foods, pharmaceuticals, and chemical substances. Among them, the most effective effect is obtained when it is applied as a light-shielding bag for various photographic light-sensitive materials.

Representative examples of various photographic light-sensitive materials are shown below, but it goes without saying that they are not limited to these.

Various silver halide photographic light-sensitive materials, various diazo light-sensitive materials, photo-fixing type heat-sensitive light-sensitive materials, photosensitive resin light-sensitive materials, UV-curable light-sensitive materials, transfer type photothermographic materials, direct positive photographic light-sensitive materials, self-developing photographic materials Photosensitive material, photosensitive material for lithographic printing (PS plate).

When the packaging material for a photosensitive material of the present invention is applied to, for example, the above photographic photosensitive material, the most effective effect is that the bottom of a cylindrical (tube-shaped) film formed by an inflation film molding method is heat-sealed flat. It is a bag or a gusset bag.

In addition, it can be used in all known forms such as laminated film, moisture-proof box inner sticking, bright room loading magazine inner sticking, light-shielding property, 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. In addition, it is also possible to use appropriate adhesive layers, pressure-sensitive adhesives, and the like for bag making.

[Operation] In the present invention, by using the second L-LDPE resin (linear low-density polyethylene resin having special characteristics), the vertical and horizontal balance is good, and the tear strength is very excellent. Impact drilling strength and heat seal suitability are secured. In addition, the addition of carbon black does not reduce the physical strength or heat sealability of the light-shielding film using conventional LDPE resin or HDPE resin. Conversely, when carbon black is added within the range of 10% by weight or less. In addition, the tear strength and heat sealability are better than in the case of no addition, and the antioxidant action is also strengthened.

Further, by using the L-LDPE resin having the first special property, while maintaining the excellent properties of the second L-LDPE resin, the low Young's modulus and blocking which are the defects of the second L-LDPE resin are obtained. It has been found for the first time that not only the occurrence of the above phenomenon, the crystallization rate, etc., but also the haze is increased and the light-shielding property is improved by 10% or more even with the same amount of carbon added, which is an unexpected effect. Furthermore, the tensile strength is the second L-LD.
As a result of improving compared to the case of using PE resin alone, it is less likely to cause one-sided elongation during film molding, less drawdown, wrinkles, and streaks are generated, bubble stability is good during inflation film molding, and melt fracture occurs. Difficult to do, excellent in smoothness and product insertability.

〔Example〕

An embodiment of the packaging material for the photosensitive material of the present invention will be described with reference to FIGS. 1 to 5.

1 to 5 are partial cross-sectional views showing the layer structure of a packaging material for a photosensitive substance.

The packaging material for a photosensitive material shown in FIG. 1 is composed of a single layer film of a polyolefin resin light-shielding film 1a.

The photosensitive material packaging material of FIG. 2 is composed of two layers, a polyolefin resin light-shielding film 1a and a thermoplastic resin film layer 2a containing a light-shielding substance.

The photosensitive material packaging material of FIG. 3 is composed of two layers, a polyolefin resin light-shielding film layer 1a and a thermoplastic resin film layer 2 containing no light-shielding substance.

The photosensitive material packaging material shown in FIG. 4 includes a polyolefin resin light-shielding film 1a, a flexible sheet 4 and an adhesive layer 3
It is composed of three layers that are laminated via.

The packaging material for the photosensitive material shown in FIG. 5 has 3 sheets of the polyolefin resin light-shielding film 1a laminated with the adhesive layer 3 interposed therebetween.
It is composed of layers.

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

The comparative example of FIG. 6 is composed of a single layer film of the HDPE resin film 5a containing a light-shielding substance.

The comparative example of FIG. 7 is composed of a single layer film of the L-LDPE resin film 6a containing a light-shielding substance.

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

The product I of the present invention has a layer structure corresponding to FIG.

The polyolefin resin light-shielding film 1a has an MI of 2.1 g / 1
It is a copolymer of ethylene and 4-methylpentene-1 with a density of 0.935 g / cm ³ and an Orzens rigidity of 4200 kg / cm ² at 0 minutes.
20% by weight of L-LDPE resin, MI 0.8g / 10 minutes, density 0.906
76.85% by weight of a second L-LDPE resin, which is a copolymer resin of g / cm ³ of ethylene and butene-1, carbon black (average particle size 21 mμ, pH 8.0, oil furnace carbon black # 44B, Mitsubishi Kasei) 3% by weight, oleic acid amide
70μ thickness consisting of 0.03% by weight, calcium stearate 0.07% by weight, antioxidant (BHT) 0.05% by weight resin composition
m is a monolayer blown film.

The present invention II layer structure corresponds to FIG.

The polyolefin resin light-shielding film 1a has an MI of 1.0 g / 1
The first L- which is an ethylene-octene-1 copolymer resin having a density of 0.935 g / cm ³ and an Orsen rigidity of 4600 Kg / cm ² for 0 minutes.
LDPE resin 20% by weight, MI 1.0g / 10min, density 0.890g / cm ³
Second L which is a copolymer resin of ethylene and butene-1
-LDPE resin 76.85% by weight, carbon black (above) 3
A single-layer blown film having a thickness of 70 μm, which is composed of a resin composition of wt%, oleic acid amide 0.03 wt%, calcium stearate 0.07 wt%, and antioxidant (BHT) 0.05 wt%.

The present invention III layer structure corresponds to FIG.

The polyolefin resin light-shielding film 1a has a density of 0.93
5 g / cm ³ , MI 2.1 g / 10 min, Olsen rigidity 4200 Kg / cm ² 35% by weight of the first L-LDPE resin which is a copolymer resin of ethylene and 4-methylpentene-1, MI 1.95 g / 10 minutes, density
61.85% by weight of a second L-LDPE resin which is a copolymer resin of 0.911 g / cm ³ of ethylene and 4-methylpentene-1; 3% by weight of carbon black (supra); 0.03% by weight of oleic acid amide; calcium stearate. A single-layer blown film having a thickness of 70 μm and composed of a resin composition of 0.07% by weight and an antioxidant (BHT) of 0.05% by weight.

Comparative product I The layer structure corresponds to FIG.

The HDPE resin film 5a containing a light-shielding substance has an MI of 1.1 g / 1
A thickness of 70 minutes consisting of a resin composition of 97 minutes by weight of HDPE resin having a density of 0.954 g / cm ^{3 for} 0 minutes and ³ % by weight of carbon black (described above).
It is a monolayer blown film of μm.

The comparative product II layer structure corresponds to FIG. 7.

The L-LDPE resin film 6a containing a light-shielding substance has an MI of 1.
Thickness of 0 g / 10 min, density of 0.890 g / cm ³ and the same resin composition of the second L-LDPE resin used in the present invention II as 97% by weight and carbon black (above) as 3% by weight. It is a single-layer blown film of 70 μm.

The conventional I-layer structure corresponds to FIG.

LDPE resin film 7a containing a light-shielding substance has an MI of 2.4 g / 10
70μ thickness consisting of 97% by weight LDPE resin with a density of 0.923 g / cm ³ and ³ % by weight carbon black (previously mentioned).
m is a monolayer blown film.

Table 1 below shows the results of comparison between the present invention products I to III, the comparative products I and II, and the conventional product I.

The evaluation is as follows.

◎… Extremely good ○… Excellent ●… Practical limit ▲… Problem, need improvement ×… Not practical * 1 Blocking resistance * 3 Leave the inflation film for 3 days after molding and winding Judgment and evaluation of the blocking (adhesion) condition when winding and wrapping the film based on the difficulty of peeling * 2 Heat-sealing suitability, hot-tacking property, heat-sealing property of contaminants, heat-sealing strength, heat-sealing strength over time, allowable heat-sealing width * 3 Film moldability Stability of bubbles, drawdown, wrinkles when forming an inflation film with a blow ratio of 1.76 and a thickness of 70 μm using a ring die with a diameter of 100 mm and a lip clearance of 1 mm. Comprehensive evaluation of streak generation, film thinning, etc. [Effect of the invention] The photosensitive material packaging material of the present invention shows no blocking. , Greater physical strength is less generation of static electricity is a film formability, sealability is good, is excellent in moistureproof light-shielding property.

The blown film is excellent in moldability and can be used as a tubular film as it is, to package a bulk roll of a roll-shaped photosensitive material having a diameter of 25 cm or more, a large weight, and a large volume.

Further, only by heat-sealing the bottom, a curling is small, and a packaging bag having excellent mouth opening property, physical strength, heat-sealing strength, and moisture-proof / light-shielding property can be obtained at low cost. As described above, since the packaging material was easily obtained from the blown film without loss of material, it is inexpensive, and the packaging workability is good, so productivity is good, and it is possible to work alone, so it is only necessary to reduce the cost of packaging material. The cost can be reduced by saving labor.

Further, when the inflation film is slit at both ends and laminated on another flexible sheet as a sheet-like film, more excellent properties can be added, and it is particularly excellent as a packaging material for a silver halide photographic light-sensitive material.

[Brief description of drawings]

1 to 5 are partial cross-sectional views showing a layer structure of an embodiment of a packaging material for a photosensitive material according to the present invention, and FIGS. 6 and 7 are partial cross-sectional views showing a layer structure of a comparative example, and FIG. Is a partial cross-sectional view showing a layer structure of a conventional example. 1a: Polyolefin resin light-shielding film 2, 2a: Thermoplastic resin film 3, 3a: Adhesive layer 4, 4a: Flexible sheet a represents carbon black or a light-shielding substance.

Claims (1)

[Claims] 1. A first linear low-density polyethylene resin having a melt index of 0.6 to 15 g / 10 minutes, a density of 0.925 to 0.945 g / cm ³ , and an Orsen rigidity of 3500 Kg / cm ² or more, 10 to 90% by weight, Melt index 0.3-20g / 10min, density 0.870
~ 0.915g / cm ³ of second linear low density polyethylene resin 5
~ 89% by weight, carbon black 0.1-20% by weight, fatty acid and / or fatty acid compound 0.01-5% by weight, antioxidant 0.
A packaging material for a photosensitive material, comprising a polyolefin resin film containing at least 5 components of 01 to 2.0% by weight