JPH0264537A - Wrapping material for photosensitive substance - Google Patents

Abstract

PURPOSE:To improve the physical strength, the shielding property and the heat-sealing property of the wrapping material by composing the subject material of a combination of two kinds of specified ethylene copolymers. CONSTITUTION:The wrapping material is constituted of a monolayer or a multilayer film comprising at least 5 components of 10-90wt.% of a 1st. straight chain low density polyethylene resin (A), 5-89wt.% or a 2nd. straight chain low density polyethylene resin (B), 0.1-20wt.% of a carbon black, 0.01-5wt.% of fatty acid (a compd.) and 0.01-2.0wt.% of an antioxidant. The component (A) is composed of for example, an ethylene 4 methylpentene-1 copolymer and has melt index of 0.6-15g/10min, density of 0.925-0.945g/cm<3> and olsen rigidity of >=3,500kg/cm<2>. The component (B) is composed of four example, an ethylene- buten-1 copolymer and has the melt index of 0.3-20g/10min and the density of 0.870-0.915g/cm<3>.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a packaging material for photosensitive materials, and in particular to a packaging material for photosensitive materials that has good physical strength, light shielding properties, and heat sealability even when only a single layer film is used. be.

[Conventional technology]

For materials such as photosensitive materials that lose their quality value when exposed to light, packaging bags that completely block light are used. In addition to the above-mentioned light-shielding properties, this packaging bag must have sufficient physical strength according to the size and weight of the photosensitive material, such as tensile strength, tear strength, impact puncture strength, etc., and the opening must be sealed by heat sealing. Due to the nature of the process, heat sealability is required. Furthermore, in order to insert the photosensitive material into the packaging bag, anti-blocking properties (opening properties) and slip properties are required.

Furthermore, antistatic properties are also required to prevent charging due to friction between the photosensitive material and the packaging bag.

Conventionally, packaging materials used for such packaging bags include high-pressure branched low-density polyethylene (hereinafter referred to as LDPE) resin film added with carbon black, aluminum foil, and bleached kraft paper, and DPE resin melt extrusion. Some were laminated sequentially with adhesive layers.

In addition, the present inventor has used a uniaxially stretched high-density polyethylene (hereinafter referred to as HDPE) resin film, which has high physical strength, as a packaging material (in particular, a sealed light-shielding bag) for roll-shaped photosensitive materials and laminated sheet-shaped photosensitive materials weighing 1 kg or more. proposed a laminated film in which an LDPE resin film containing at least one of a light-shielding substance and an antistatic agent was laminated on a cross-laminated film (Japanese Utility Model Publication No. 19087/1987).

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

Furthermore, as a packaging material using a metallized film, 50% by weight or more of L-L is added on both sides of the metallized film.
We have proposed a packaging material for photosensitive materials that contains a DPE resin and is laminated with an L-LDPE resin polymer layer containing 0.3 to 30% by weight of a light-shielding substance on one or both sides (Japanese Patent Laid-Open No. 1983-1992).
-54934).

Furthermore, it has been difficult to use packaging materials made of single-layer films for packaging bags that require various properties, such as light-shielding bags for photographic materials. Therefore, single-layer film packaging materials have low photosensitivity, are lightweight, and are used only as packaging bags for photographic materials and lightweight photographic paper that use protective paper. For example, as shown in Figure 8, There are those made of LDPE resin film 7a to which carbon black has been added, and those made of LDPE resin film 7a to which carbon black has been added.
There was one made of PE resin film.

[Problem to be solved by the invention]

Laminated film with conventional LDPE resin film is
Because it is thick and rigid, packaging workability is poor (and despite its thickness, physical strength (tear strength, etc.) is low, curling is large, it is expensive, and heat sealability is poor, making packaging work difficult) It was difficult to ensure light-shielding, moisture-proofing, and gas-barrier properties because dust was generated inside the product or during transportation, holes were formed, the product was torn, and the heat-sealed portion was peeled off.

Also, the 19087 calyx publication and the 1987 calyx publication.
The packaging material having a cross-laminated film proposed in Publication No. 20590 has greatly improved physical strength such as tear strength and tensile strength, so it is excellent as a packaging material for heavy substances, and was put into practical use until recently. However, since a uniaxially stretched high-density polyethylene resin film is used for the heat-sealing layer, it has high rigidity, poor packaging workability, and poor heat-sealability. Variations caused curling and changes in physical strength, which sometimes caused peeling and tearing.

Further, a cross-laminated film in which a longitudinally-axially stretched film and a horizontally uniaxially stretched film are laminated so that their stretching axes intersect requires the use of two types of film forming machines, resulting in an expensive laminated film.

The packaging material proposed in Japanese Patent Application Laid-Open No. 61-54934 is
Although physical strength such as tear strength has been improved, packaging materials in which an L-LDPE resin film containing a light-shielding substance is laminated on only one side of a metallized film suffer from increased curling. In addition, L-LDP with approximately the same melting point on both sides
When E-resin films are laminated, unless special processing is applied to the heat-sealing device, the outer layer will melt and break, causing pinholes and strength deterioration, as well as deteriorating the appearance. .

For this reason, laminated films made by laminating aluminum vacuum-deposited nylon films and polyester films, which have a large Young's modulus and are heat resistant, have been put into practical use, but these nylon films suffer from extremely high curling and are expensive.

For single-layer films, LD containing thick carbon black
PE resin films have low physical strength and poor heat sealability, making it difficult to ensure 100% quality of photosensitive materials.

Also, JP-A-61-189936 and JP-A-62-1989
A packaging material having a single-layer light-shielding film using a resin composition in which carbon black is added to L-LDPE resin, which was proposed in Publication No. 18547, is inexpensive, has good heat sealability, and has excellent tear strength and impact puncture strength. This makes it an excellent packaging material for photosensitive materials.

However, when packaging heavy products, the Young's modulus is small, so although holes and tears do not occur in L-LDPE resin light-shielding films, they sometimes become stretched and thin, making it impossible to ensure sufficient light-shielding and moisture-proofing properties. .

In addition, in the blown film molding method, the density is 0.
Blocking was likely to occur in films using L-LDPE resin with a weight of 925 g/ail or less. Density is 0.
925 g/c++] or more, films using L-LDPE resins sometimes lacked pinhole resistance and tear strength at low temperatures.

The present invention solves the above problems and is a non-uniform mass with excellent physical strength, no blocking, excellent heat sealability, excellent pinhole resistance and tear strength even at low temperatures. It is an object of the present invention to provide a packaging material for photosensitive materials that uses a polyolefin resin light-shielding film that generates little oxidation and can ensure 100% quality of the photosensitive materials.

[Means to solve the problem]

The present invention was made to achieve the above object, and was achieved by using a combination of L-LDPE resins having a specific resin composition.

That is, the packaging material for photosensitive materials of the present invention has a melt index of 0.6 to 15 g/10 minutes and a density of 0.925.
~0.945g/cffl, Olzen stiffness is 3500K
g/cm" or more first linear low density polyethylene resin 10 to 90% by weight, melt index 0.3 to 20
g/10 minutes, density 0.870-0.915g/cm3
5-89% by weight of the second linear low-density polyethylene resin
, carbon black 0.1-20% by weight, fatty acids and/or
Or fatty acid compound 0.0f to 5% by weight, antioxidant 0.
It is characterized by comprising a polyolefin resin light-shielding film containing at least 5 components of 0.01 to 2.0%.

The first L constituting the polyolefin resin light-shielding film
-LDPE resin has an M I (JIS L6760) of 0.6 to 15 g/10 min and a density (JIS K-6760) of 0.6 to 15 g/10 min.
) is 0.925 to 0.945g/c4. Olzen stiffness (
JIS K-7106) is 3500 Kg/cm" or more and is contained in an amount of 10 to 90% by weight.

If the first L-LDPE resin is less than 10%, L-LD
It is not possible to improve the disadvantages of PE resin, such as low Young's modulus, low tensile strength, blocking, and lack of lubricity, and the cost of blending increases. In addition, film formability is poor (occurrence of drawdown, lack of bubble stability, etc.),
Even if the film can be formed, it will be difficult to put it into practical use if the bag-making suitability of the light-shielding bag is poor due to blocking or one-sided elongation due to insufficient tensile strength.

On the other hand, if it exceeds 90% by weight, the tear strength in the lateral direction decreases, and the balance between the tear strength in the longitudinal and lateral directions deteriorates, making the bag more likely to break. Moreover, the addition of carbon black deteriorates various physical properties, heat sealability, etc., contrary to the case of the present invention.

In addition, more uneven lumps are generated, which not only deteriorates the appearance but also adversely affects the photosensitive material.

When Ml is less than 0.6 g/10 minutes, film formability is poor and molecules are easily oriented in the longitudinal direction, making it difficult to obtain a film with a good balance of longitudinal and transverse physical strength. Moreover, unrestricted lumps occur frequently and easily damage the photosensitive material.

When Ml exceeds 15 g/10 minutes, drawdown and bubble shaking occur, making film forming difficult.

From the viewpoint of physical strength, appearance, film formability, etc. of the film, Ml is preferably in the range of 1.0 to 5.0 g/10 min.

If the density is less than 0.925 g/cff1, the second L
-It becomes impossible to cover the defects of LDPE resin. For example, blocking is more likely to occur, Young's modulus and tensile strength become smaller, and single-layer films stretch when tension is applied.
It becomes thinner and cannot ensure light-shielding and moisture-proof properties.

When the density exceeds 0.945 g/c1if, molecular orientation tends to occur, the difference in longitudinal and lateral tear strength becomes large, heat sealability decreases, and non-uniform lumps often occur.

Preferably the density is 0.930-0.942g/cffl
is within the range of

If the Orzen stiffness is less than 3500 kg/cm, the film formability will deteriorate. Also, the Young's modulus and tensile strength will decrease, and a single-layer film will stretch when tension is applied, becoming thinner and unable to ensure light-shielding and moisture-proofing properties. .

The second L constituting the polyolefin resin light-shielding film
- the LDPE resin has an Ml of 0.3 to 20 g/10 min, a density of 0.87 to 0.915 g/cd, and
Contains 89% by weight.

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

When used in excess of 89% by weight, film formability deteriorates and blocking tends to occur. Furthermore, the Young's modulus and tensile strength become small, and a single-layer film is stretched when tension is applied, becomes thinner, and cannot secure light-shielding and moisture-proof properties.

If Ml is less than 0.3 g/10 minutes, the motor load becomes large and melt fracture tends to occur (which makes it difficult to put it into practical use).Moreover, molecules tend to be oriented in the vertical direction.

When Ml exceeds 20 g/10 minutes, blocking tends to occur, bubbles become unstable, and film forming becomes difficult.

If the density is less than 0.87 g/ci1, the resin not only becomes expensive (blocking tends to occur, bubbles become unstable and film forming becomes difficult).

If the density exceeds 0.915g/cn, the first L-LD
It becomes impossible to cover the defects of PE resin, and it becomes impossible to obtain a polyolefin resin light-shielding film with excellent low-temperature heat-sealability, pinhole resistance, and tear strength. In addition, pinhole resistance and tear strength at low temperatures decrease.

The L-LDPE resin that forms the first L-LDPE resin and the second L-LDPE resin is an ethylene copolymer resin that is inexpensive and has high physical strength (especially when a light-shielding substance is added). Referred to as the third type of polyethylene resin, it combines the advantages of both medium-low pressure and high-pressure polyethylene resins, and is low cost and meets the demands of the times for energy and resource conservation.
It is a high strength resin.

This L-LDPE resin is produced by a low-pressure method or a high-pressure modification method using ethylene and α-carbon atoms having 3 to 13 carbon atoms, preferably 4 to 10 carbon atoms.
It is a copolymer made by copolymerizing olefins, and is a low-medium density polyethylene resin with a linear structure with short branches.

α-olefins include butene-1, octene-1, hexene-1,4-methylpentene-11, butene-1,
etc. are used, and the density is generally considered to be about that of low-medium density polyethylene resin, but commercially available products are 0.87 to 0.95 g.
Many of them are within the range of /cj.

Specific examples of L-LDPE resins by trade name include G Resin, TUFLIN, and NUC-FLX (UCC), Dowlex (Dow Chemical), Sflare (DuPont Canada), Marlex (Philips), NUC
Polyethylene-LL and TUFTHENE (Nippon Unicar), Neo-Zex and Ult-Zex (Mitsui Petrochemical), F-selen VL (Jumin Chemical), Megasu Nilex (
Japan Petrochemical), Idemitsu Polyethylene-L and MORET
Examples include EC (Idemitsu Petrochemical), Mitsubishi Polyethylene LL (Mitsubishi Yuka), and Stamilex (DSM).

Among these L-LDPE resins, melt index (hereinafter M
l) is 0.3 to 20g/10 minutes (JISK-67
60), with a density of 0.870 to 0.945 g/afl (J
IS K6760), and α-olefin carbon number 4
~13 liquid phase or gas phase processes.

Particularly preferred representative examples include the product names of Mitsui Petrochemical's Urtozex, which has 4-methylpentene-1, which has 6 carbon atoms, introduced into ethylene as an α-olefin side chain; number 8 octene-
DSM's Stamilex, Dow Chemical's Dowlex, and Idemitsu Petrochemical's MORETEC, which have introduced 1, etc.
It is DPE resin. ).

One of the components constituting the polyolefin resin light-shielding film
In addition to providing light-shielding properties, carbon black not only improves tear strength, impact punching strength, and heat-sealing suitability, but also prevents oxidation of the resin to prevent spots, prevents blocking, improves lubricity, and adsorbs harmful substances ( It is the most important substance that plays many roles such as redox substances, metals, etc.

Carbon black is contained in an amount of 0.1 to 20.0% by weight.

If it is less than 0.1% by weight, the effect of adding carbon black (ensuring light-shielding properties, preventing static electricity, etc.) cannot be expected, and the cost increases by the kneading cost.

If it exceeds 20.0% by weight, the physical strength of the film, especially tearing strength and impact puncturing strength, will decrease and heat sealability will deteriorate. Furthermore, failures often occur in which the photosensitive material is contaminated by the carbon black on the film surface or the carbon black separates from the film and adheres 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, those with a pH of 5 to 9 and an average particle size of 10 to 200 mμ are preferable, particularly those with a pH of 6 to 9.
9. Furnace carbon black with an average particle diameter of 50 square meters or less is preferred because it is inexpensive, has a large light-shielding ability, and has excellent crosstalk dispersion. In some cases, it may be preferable to use acetylene black, ketchiene carbon black, or graphite, which are expensive but have excellent antistatic effects.

By using particles with such pH and particle size, there is less generation of capri, less increase and decrease in photosensitivity, greater light shielding ability, and less carbon black lumps.
It is possible to obtain a light-shielding film that has a number of advantages, such as improved physical strength and improved heat-sealability, which makes pinholes less likely to occur due to fish eyes and the like.

The above various carbon blacks may be used alone or in combination of two or more types, and when used in combination with antistatic agents such as metal fibers, carbon fibers, metal powder, various surfactants, conductive substances, etc., conductivity can be improved. This is preferable because it allows

The forms in which carbon black is blended with resin are colored pellets, die-colored granules, and liquid.
Color A variety of known forms such as dry color and masterbatch can be used, but masterbatch and dye color granules are preferred from the viewpoint of cost reduction and prevention of contamination of the workplace.

One of the components constituting the polyolefin resin light-shielding film
The fatty acids and fatty acid compounds are used alone or in combination.

Fatty acids and fatty acid compounds are polymerization catalysts that not only neutralize and detoxify halides and other substances that have a harmful effect on photosensitive materials, but also prevent blocking, improve the dispersibility of carbon black,
It plays the role of improving lubricity, improving film formability, and improving bag-making 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 L-LDPE resin, this problem is prevented and the heat sealability is extremely excellent.

Fatty acids and/or fatty acid compounds are 0. Use O1-5 heavy view%. If it is less than 0.01% by weight, the effect of the addition will not be apparent, and if it exceeds 5% by weight, the fluctuation in resin discharge amount will increase due to screw slip, which will not only deteriorate film formability but also result in a film with large fluctuations in thickness. becomes.

Typical fatty acids include oleic acid, stearic acid,
Lauric acid, ricinoleic acid, naphthenic acid, octylic acid,
These include saturated and unsaturated fatty acids such as phthalic acid, adipic acid, sepatic acid, acetyl ricinoleic acid, and maleic acid.

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, and octylic acid. These include zinc, butyl oleate, butyl stearate, etc.

One of the components constituting the polyolefin resin light-shielding film
The antioxidant reduces the occurrence of spots due to oxidation of the resin during long-term continuous film forming, and when used as a light-shielding bag, prevents the occurrence of push scratches, scratches, pressure fog, etc. caused by the spots. If a large) problem occurs,
In addition to the above-mentioned failures, heat sealing failures occur, making it impossible to ensure light-shielding properties, moisture-proofing properties, and gas barrier properties, and making it impossible to ensure the quality of photosensitive materials.

The antioxidant is not limited to the use of one type, but two or more types may be used in combination. In some cases, the antioxidant effect can be improved by using them together. For example, a combination of a phenolic antioxidant and a phosphorus antioxidant, a combination of a volatile antioxidant and a heat-resistant antioxidant, etc. are used.

Moreover, by using the antioxidant effect of carbon black in combination, a synergistic effect of antioxidant is exhibited.

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 addition effect will hardly be exhibited and the cost will increase by the kneading cost.

If the amount exceeds 2.0% by weight, abnormal photographic performance will occur in photographic materials that utilize oxidation and reduction effects.

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

As antioxidants that can be used in the present invention, 794-799 of Plastic Handbook (published by KK Industrial Research Association)
Page, pages 327-329 of Plastic Additive Data Collection (published by KK Chemical Industry Co., Ltd.), PLA-STIC5
AGE ENCYCLOPEDIA Progress Edition 1986 (K
There are various antioxidants disclosed on pages 211-212 of K Plastics Age).

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

Phenolic n-octadecyl-3 (3',5'-di-t-butyl4
゛Hydroxyphenyl)propinate, 2.6-di-butyl-4-methylphenol, 2.6-di-t-butyl-p-cresol, 2.2゛-methylenebis(4-methyl-6-butylphenol) , 4.4"-thiobis(3-methyl-6-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
-L-butylphenyl)butane, 1.3.5-trimethyl-2,4,6-)lis(3,5
-dibutyl-4-hydroxybenzyl)benzene, octadecyl-3,-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, tetrakis[methylene-3(3',5'-di-t -Butyl-4'-hydroxyphenyl)propionate comethane, etc. Sulfur-based dilauryl-3,3''-thiodipropionate, similystyl-3,3''-thiodipropionate, laurylstearylthiodipropionate, distearyl- 3'-
Thiodipropionate, ditridecyl-3,3°-thiodipropionate, etc. Phosphorous trinonylphenyl phosphite, triphenyl phosphite, etc. Especially 2,6-di-t-butyl-p-cresol (BHT)
) and low-volatility high molecular weight phenolic antioxidants (product names 1reganoxlO10, lreganox107)
It is effective to use one or more, especially two or more of 6°TOPanol CA, Ionox 330, etc.), dilaurylthiodipropionate, distearylthiodipropionate, and sialkisphosphate.

The polyolefin resin light shielding film used in the present invention includes:
It is also possible to add various thermoplastic resins. For example, various polyolefin resins such as LDPR resin, MD
PE resin, polypropylene resin, propylene-ethylene copolymer resin, EVA resin, EMA resin, EEA resin,
These include EAA resin, ionomer resin, ethylene-unsaturated carboxylic acid copolymer resin, ethylene-unsaturated carboxylic acid ester copolymer resin, various ethylene-alkyl ester copolymer resins, and various elastomers.

The polyolefin resin light-shielding film used in the present invention can completely prevent blocking even without the addition of an anti-blocking agent. is 0.910g/c1i! In the case of applications where blocking is guaranteed to be completely prevented even if the following ultra-low density L-LDPE resin is contained in an amount of 50% by weight or more, various anti-blocking agents may be added.

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

Furthermore, various additives may be added within a range that satisfies the properties of the polyolefin resin light-shielding film of the present invention.

Representative examples of additives are described below, but the present invention is not limited thereto, and any known additives can be selected.

(Additive types) (Representative examples) (1) Plasticizers: Phthalate esters, glycol esters, fatty acid esters, phosphate esters, etc. (2) Stabilizers: Lead-based, cadmium-based, zinc-based, alkaline earth metal-based , organic tin-based, etc. (3) Antistatic agents and conductive substances: cationic surfactants, anionic surfactants, nonionic surfactants, bifacial active agents, various carbon blacks, metal powders, graphite , etc. (4) Flame retardants; phosphoric acid esters, halogenated phosphoric acid esters, halides, inorganic substances, phosphorus-containing polys, alls, etc. (5) Fillers; alumina, kaolin, clay calcium carbonate, mica, talc, titanium oxide, silica, etc. (6) Reinforcing agent; Glass roving, metal fiber, glass fiber, glass milled fiber, carbon fiber, etc. (7) Coloring agent; Inorganic pigment (All, Fe2031
rtoz.

ZnO, CdS, etc.), organic pigments (carbon black, dyes, etc.), etc. (8) Blowing agents; inorganic blowing agents (ammonia carbonate, sodium bicarbonate), organic blowing agents (Troso type, azo type), etc. (9) Deterioration prevention Agents: UV absorbers, antioxidants, metal deactivators, peroxide decomposers, etc. (10) Lubricants: Paraffins, waxes, fatty acids, fatty acid amide types, silicone types, ester types, higher alcohols, etc. (11) Coupling agents: Silica-based, titanate-based, chromium-based, aluminum-based, etc. The packaging material for photosensitive materials of the present invention can be used as a single layer film, or it can be laminated with other flexible sheets to make it even more superior. It may also be used as a laminated film with additional properties.

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

The packaging material for photosensitive materials of the present invention exhibits great effects only when an blown silane film is used.

A package using the blown cylindrical film of the present invention, which does not cause blocking, is flexible, has high physical strength, and generates little static electricity, is preferable because it makes it possible to completely reduce costs and ensure quality.

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

Representative examples of various photographic materials are shown below, but it goes without saying that the invention is not limited to these.

Various silver halide photographic materials, various diazo-sensitive materials,
Light-fixable heat-sensitive materials, photosensitive resin materials, ultraviolet curable materials, transfer-type heat-developable materials, direct positive photographic materials, self-developing photographic materials, and lithographic materials (23 editions).

When the packaging material for photosensitive materials of the present invention is applied to, for example, the above-mentioned photographic materials, the most effective method is to heat-seal the bottom of a cylindrical (tubular) film formed by the blown film method. It is a bag or a gusset bag.

It can be used in all known forms such as laminated film, inner lining of moisture-proof boxes, inner lining of light-shielding magazines for loading in bright rooms, and leader paper.

The bag making method is based on conventionally known plastic film sealing methods such as heat sealing, fusing sealing, impulse sealing, ultrasonic sealing, and high frequency sealing, depending on the properties of the laminated film used. In addition, it is also possible to make bags using an appropriate adhesive layer, adhesive, etc.

[Effect]

In the present invention, by using the second L-LDPE resin (linear low-density polyethylene resin with special properties), it has a good vertical and horizontal balance, and has excellent tear strength and impact strength. Drilling strength and heat sealability are ensured. In addition, the addition of carbon black is also different from conventional LD.
There is no decrease in physical strength or heat sealability as with light shielding films using PE resin or HDPE resin, and on the other hand, when carbon black is added in an amount of 10% by weight or less, the tear strength is higher than when no additive is added. The heat sealability is improved, and the antioxidant effect is also strengthened.

In addition, by using L-LDPE resin having the first special property, while ensuring the excellent properties of the second L-LDPE resin, the low Young's modulus, which is the drawback of the second L-LDPE resin It has been found for the first time that it not only improves the occurrence of blocking and crystallization speed, but also increases the haze and has the unexpected effect of improving the light-shielding property by more than 10% with the same amount of carbon added. Furthermore, as the tensile strength is improved compared to when the second L-LDPE resin is used alone, one-sided elongation during film molding is less likely to occur, drawdown, wrinkles, and streaks are less likely to occur, and bubbles are prevented during blown film molding. Good stability, less chance of melt fracture, excellent smoothness and ease of product insertion.

〔Example〕

Examples of the packaging material for photosensitive materials of the present invention are shown in Figures 1 to 5.
This will be explained based on the diagram.

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

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

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

The packaging material for photosensitive materials shown in 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 packaging material for photosensitive materials shown in FIG.
It is composed of three layers laminated with .

The packaging material for photosensitive materials shown in FIG.
It is composed of layers.

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

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

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

Next, the results of an experiment comparing the characteristics of products ① to ② of the present invention, comparative products I and ②, and conventional product 1 will be explained.

Invention product I The layer structure corresponds to that shown in FIG.

The polyolefin resin light-shielding film 1a has Ml of 2.
20% by weight of the first L-LDPE resin, which is a copolymer of ethylene and 4-methylpentene-1, with a density of 0.935 g/d and an Olzen stiffness of 4200 Kg/cn'', Ml of 0.8 g /10 minutes, density 0.906g/c
The second is a copolymer resin of ethylene and butene-1 of m3.
Noshi-LDPR resin 76.85% by weight, carbon black (average particle size 21, pH 8.0, oil furnace carbon black #44B, manufactured by Mitsubishi Kasei) 3% by weight, oleic acid amide 0.03% by weight, calcium stearate It is a single-layer blown film with a thickness of 70 μm, consisting of a resin composition of 0.07% by weight and 0.055% by weight of an antioxidant (BHT).

Invention product■ The layer structure corresponds to that shown in FIG.

The polyolefin resin light-shielding film 1a has Ml of 1.
0g/10min, density 0.935g/c4. 20% by weight of a first L-LDPE resin which is an ethylene-octene-1 copolymer resin with an Olzen stiffness of 4600 Kg/cm";
MI is 1.0g/10min, density is 0.890g/cm3
The second L is a copolymer resin of ethylene and butene-1.
-LDPE resin 76.85% by weight, carbon black (
(previous) 3% by weight, oleic acid amide 0.03% by weight, calcium stearate 0.07% by weight, antioxidant (B
IT) Thickness 70.8 consisting of 0.05% by weight resin composition
11 single layer blown film.

Invention product■ The layer structure corresponds to that shown in FIG.

The polyolefin resin light-shielding film 1a has a density of 0.
935 g/aff SM I is 2.1 g/10 min, Olzen stiffness force is 4200 Kg/cm" 35% by weight of the first L-LDPE resin which is a copolymer resin of ethylene and 4 methylpentene-1, Ml is 1.95 g /10 minutes, density is 0.
911g/cil of ethylene and 4 methylpentene-1
A second L-LDPE resin, which is a copolymer resin of 81.8
5% by weight, carbon black (mentioned above) 3% by weight, oleic acid amide 0.03% by weight, calcium stearate 0
．． Comparative product I, which is a single-layer blown film with a thickness of 70 μm, having a resin composition of 0.07% by weight and 0.05% by weight of antioxidant (BHT).The layer structure corresponds to that shown in FIG.

The HDPE resin film 5a containing a light-shielding substance is made of 97% by weight of HDPE resin with an Ml of 1.1 g/10 min and a density of 0.954 g/c11I, carbon black (mentioned above) 3
It is a single layer blown film with a thickness of 70jm consisting of a resin composition of % by weight.

Comparison product ■ The layer structure corresponds to that shown in FIG.

The L-LDPE resin film 6a containing a light-shielding substance is M
A second L-LDPE resin 9 which is the same as that used in the product of the present invention (1) with l of 1.0 g/10 min and a density of 0.890 g/c
It is a single-layer blown film with a thickness of 70 mm, consisting of a resin composition of 7% by weight and 3% by weight of carbon black (described above).

Conventional product ■ The layer structure corresponds to that shown in FIG.

The LDPE resin film 7a containing a light blocking substance has an MI of 2.
．． 4g, 710 minutes, density 0.923g/afi, L
This is a single-layer blown film with a thickness of 10 tm, consisting of a resin composition of 97% by weight of DPE resin and 3% by weight of carbon black (described above).

Table 1 below shows the results of comparing the products of the present invention (1) to (2), comparative products I and (2), and conventional product (2).

The evaluation is based on the following.

◎...Excellent O...Excellent...Within practical limits M...Problems, improvement required ×...Not practical *1 Blown film under the conditions of pronking *3 After winding the film, leave it for 3 days and evaluate the blocking (adhesive) condition when removing the film from the difficulty of peeling *2 Heat seal suitability Hot tack property, contaminant heat seal property, heat seal property Comprehensive evaluation of 5 points: strength, heat-sealing strength decrease over time, and heat-sealing allowable width *3 Film formability Using a ring die with a diameter of 100mm and a riff relief of 1mm, inflation was performed to a thickness of 70mm at a blow ratio of 1.76. Comprehensive evaluation of bubble stability, occurrence of drawdown, occurrence of wrinkle lines, film thickness, etc. when the film is formed [Effects of the Invention] The packaging material for photosensitive materials of the present invention does not cause blocking, It has high physical strength, generates little static electricity, has good film formability and heat sealability, and has excellent moisture-proof and light-shielding properties.

The blown film has excellent formability, and can be used to package bulk rolls of roll-shaped photosensitive materials with a diameter of 25 cm or more, a large weight, and a large volume using the blown film as it is in the form of a tube.

In addition, by simply heat-sealing the bottom, curling is small, opening property, physical strength, heat-sealing strength, and moisture-proofing.
A packaging bag with excellent light-shielding properties can be obtained at low cost. As mentioned above, packaging materials can be easily obtained from blown film without material loss, making it inexpensive, and packaging workability is good, resulting in high productivity. Instead, it is possible to reduce costs by saving labor.

Further, when both ends of the blown film are slit to form a sheet-like film and laminated with other flexible sheets, even more excellent properties can be added, and the film is particularly excellent as a packaging material for silver halide photographic light-sensitive materials.

[Brief explanation of the drawing]

1 to 5 are partial cross-sectional views showing the layer structure of an example of the packaging material for photosensitive materials according to the present invention, FIGS. 6 and 7 are partial cross-sectional views showing the layer structure of a comparative example, and FIG. is a partial cross-sectional view showing the layer structure of a conventional example. la...Polyolefin resin polarizing film 2.2a
...Thermoplastic resin film 3.3a...Adhesive layer 4.4a...Flexible sheet a contains carbon black or a light-shielding substance.

Claims (1)

[Claims] 10 to 90 weight 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 Olzen stiffness of 3500 Kg/cm^2 or more %, melt index 0.3-20g/10min, density 0.870-0.91
5g/cm^3 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 to 5% by weight,
A packaging material for a photosensitive material, comprising a polyolefin resin film containing at least five components of 0.01 to 2.0% by weight of an antioxidant.