JP2006263991A - Packaging material for photosensitive material, photosensitive and heat-sensitive material or heat-sensitive material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a packaging material having sufficient strength, excellent in easy tear properties and capable of being opened linearly. <P>SOLUTION: In the packaging material for a photosensitive material, a photosensitive and heat-sensitive material or a heat-sensitive material is constituted by providing an intermediate layer between the outermost layer, which comprises a heat-resistant flexible sheet, and the innermost layer composed of a shading heat-sealable layer containing high-pressure low density polyethylene, the intermediate layer is a uniaxially stretched thermoplastic resin layer characterized in that the ratio of tensile strength in its longitudinal direction and that in its lateral direction according to JIS K 7127 is 4-50. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a packaging material for a photosensitive material, a photosensitive thermosensitive material, or a thermosensitive material. More specifically, the present invention relates to a packaging material for a photosensitive material, a photosensitive thermosensitive material, or a thermosensitive material, which has sufficient strength and can be easily opened by hand.

  The photosensitive material must be stably stored until it is used without affecting the photographic performance. For this reason, the photosensitive material is usually stored in a state of being packaged in a packaging material composed of a film, and when it is necessary to move, the whole is further transported in a state of being stored in a packaging box or the like. When the photosensitive material is used, the packaging material is opened to take out a required number of photosensitive materials, and the remaining photosensitive material is stored by closing the opening by folding the opening. For this reason, packaging materials for photosensitive materials are required to have light-shielding properties and strength, and are easy to open and bend and easy to use for users. In addition, similar functions are required for packaging materials for photosensitive and heat-sensitive materials, and strength and ease of opening and folding are also required for packaging materials for heat-sensitive materials.

Various proposals have heretofore been made for the construction of packaging materials for photosensitive materials, photosensitive and thermosensitive materials, or thermosensitive materials.
For example, Patent Document 1 discloses a light-shielding film comprising a polyethylene-based polymer and 1% by weight or more of a light-shielding substance, and 50% by weight or more of the total polyethylene-based polymer is low-pressure normal low-density polyethylene (L-LDPE). A packaging material having at least one layer is disclosed.
Patent Document 2 discloses a packaging material in which the outermost layer is a heat-resistant flexible sheet layer, the intermediate layer is a uniaxial molecular alignment thermoplastic resin film layer, and the innermost layer in contact with the photosensitive material is a layer containing 50% or more of L-LDPE. Is disclosed.

Patent Document 3 discloses a light-shielding heat seal in which an outermost layer is a heat-resistant flexible sheet layer, an intermediate layer is an aluminum foil layer, and an innermost layer is 50% or more of high-pressure low-density polyethylene (LDPE) and contains a light-shielding substance. A packaging material that is a layer is disclosed.
In Patent Document 4, the outermost layer is a layer made of a biaxially stretched thermoplastic resin film or cellophane, the intermediate layer is a metal layer, and the innermost layer is a layer made of a polyolefin resin film, and the adhesive strength between the layers is A packaging material that is 250-2000 g / 15 mm is disclosed.

In Patent Document 5, the outermost layer is a heat-resistant flexible sheet layer, the intermediate layer is a metal layer, and the innermost layer is a layer made of a polyolefin resin film, and the longitudinal and horizontal tear strength ratio is 1.5 times or more. A packaging material is disclosed.
Patent Document 6 discloses a thermoplastic resin film containing a biaxially stretched plastic film layer, an ethylene copolymer resin and / or a thermoplastic elastomer in an amount of 5% by weight or more, and having a longitudinal and lateral tear strength ratio of 3 times or more. A packaging material having a layer is disclosed.
Japanese Patent Publication No.2-2700 JP-A 61-177236 Japanese Utility Model Publication No. 62-41531 JP-A-4-349456 JP-A-5-281665 JP-A-10-39453

Thus, various packaging materials have been proposed so far, but each packaging material has a technical problem.
For example, the packaging material described in Patent Document 1 has improved strength by using L-LDPE, but on the other hand, the unsealing property by hand is poor and the strength is low, so that the X-ray film is heavy. There was a problem that it could not be used. The packaging material described in Patent Document 2 has a problem in easiness of tearing (easy tearing) for opening, and it is necessary to provide a notch for tearing, and it is difficult to open linearly. There was a problem of being.

  The packaging material described in Patent Document 3 also has a problem that it is difficult to open linearly and the strength is insufficient. The packaging material described in Patent Document 4 has a problem of easy tearing, and it is necessary to provide a notch for tearing, and it is difficult to open linearly.

  In addition to the problem of Patent Document 4, the packaging materials described in Patent Documents 5 and 6 have a problem that the heat sealing force is insufficient, the polyolefin composition and the production method are limited, and the packaging material is expensive. In addition, the packaging material described in Patent Document 5 has a problem of insufficient strength.

  In view of these problems of the prior art, the present invention has sufficient strength, excellent tearability, and can be opened linearly for photosensitive materials and photosensitive thermosensitive materials. Another object of the present invention is to provide a packaging material for a heat sensitive material.

  As a result of intensive studies, the present inventors have found that the object can be achieved by combining LDPE with a uniaxially stretched thermoplastic resin film having a specific tensile strength ratio, and provides the present invention having the following configuration. It came to do.

  That is, the present invention relates to a photosensitive material, a photosensitive thermosensitive material or a thermosensitive material having an intermediate layer between an outermost layer composed of a heat-resistant flexible sheet and an innermost layer composed of a light-shielding heat-seal layer containing high-pressure low-density polyethylene. And the intermediate layer is a uniaxially stretched thermoplastic resin layer having a ratio of the tensile strength in the longitudinal direction to the tensile strength in the lateral direction according to JIS K 7127 of 4 to 50 times.

  The heat-resistant flexible sheet is preferably paper.

  The packaging material for the light-sensitive material, light-sensitive and heat-sensitive material or heat-sensitive material of the present invention can be easily opened by hand without providing a notch. Moreover, since it can be opened linearly, it is not broken in an unintended direction at the time of opening or after opening. Furthermore, since it has sufficient strength, it is possible to wrap a heavy X-ray film or the like.

  Hereinafter, the packaging material of the present invention will be described in detail. The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

  The packaging material of the present invention is characterized by having an intermediate layer made of a uniaxially stretched film between the outermost layer made of a heat-resistant flexible sheet and the innermost layer made of a light-shielding heat seal layer containing LDPE. Hereinafter, materials and characteristics of each layer will be described in order.

<Intermediate layer>
(Middle layer structure)
A uniaxially stretched film made of a thermoplastic resin is used for the intermediate layer.
The material for the uniaxially stretched film is not particularly limited as long as it is a thermoplastic resin. Examples thereof include high density polyethylene (HDPE), polypropylene, polyethylene terephthalate (PET), nylon, and polyvinylidene chloride.

The method for uniaxial stretching in the present invention is not particularly limited. The uniaxial stretching method includes a wet stretching method and a dry stretching method. The dry stretching method is further classified into a radiation heating method, a hot air heating method, a hot plate heating method, a roll (drum) heating method, and the like.
The wet stretching method is a method in which stretching is performed in a heated water tank, and has an advantage that the entire film is uniformly heated and is low in cost. However, since the temperature of water is 100 ° C. or less, there are disadvantages such as that the actual film temperature is around 80 ° C. and it is difficult to stretch at a high magnification, and that the water adheres to the film and that drying is necessary. For this reason, a method in which ethylene glycol or polyethylene glycol is added to raise the water temperature, a method in which wet stretching and roll stretching are used in combination may be used. The radiant heating method is a method of heating with an infrared heater or the like. The hot air heating method and the hot plate heating method are methods in which hot film circulation or a heating plate is used to heat and stretch the film. The roll heating method is a method of stretching a film with a heating roll. These methods may be used in combination as appropriate.

The draw ratio of uniaxial stretching is usually 4 to 20 times, preferably 6 to 17 times, and more preferably 10 to 15 times. Further, the direction of stretching can be appropriately selected depending on the form of the bag.
Moreover, the thickness after extending | stretching is 10-40 micrometers normally, Preferably it is 13-30 micrometers, More preferably, it is 15-20 micrometers.

  The uniaxially stretched film made of a thermoplastic resin used as the intermediate layer has a ratio of the tensile strength in the longitudinal direction to the tensile strength in the lateral direction according to JIS K 7127 of 4 to 50 times, preferably 5 to 30 times. It is more preferably ˜20 times, and particularly preferably 6 to 10 times. As long as the intensity ratio is within the above range, either the longitudinal strength or the lateral strength may be large.

  The uniaxially stretched film used for the intermediate layer may be a commercially available one. Examples of the uniaxially stretched film that can be preferably used as the intermediate layer of the present invention include Mitsui Noblen film manufactured by Mitsui Chemicals Bratech Co., Ltd. and Karariyan Y manufactured by Denki Kagaku Kogyo Co., Ltd. The former is easy to tear in the MD direction, and the latter is easy to tear in the TD direction. The packaging material of the present invention is preferably produced so that the direction in which the uniaxially stretched film is easy to tear matches the opening direction of the packaging material.

(Preferred uniaxially stretched film 1)
Examples of the uniaxially stretched film that can be preferably used for the intermediate layer of the present invention include a high-density polyethylene film described in JP-A No. 53-134838. That is, a high-density polyethylene film having a stretching ratio in the horizontal axis direction of 6 times or more and a density of 0.94 g / cm ³ or more can be preferably used as the uniaxially stretched film of the intermediate layer. The draw ratio in the horizontal axis direction of the high-density polyethylene film is preferably 10 times or more. The high-density polyethylene film is formed by, for example, extruding a high-density polyethylene resin having a density of 0.94 g / cm ³ or more with an extruder equipped with a T-die, and then extending 6 times or more in the horizontal axis direction with a tenter-type stretching machine. It can manufacture by extending | stretching. For specific examples and production examples of such a high-density polyethylene film, Examples 1 and 2 of JP-A-53-134838 can be referred to.

(Preferred uniaxially stretched film 2)
Another uniaxially stretched film that can be preferably used for the intermediate layer of the present invention is 20 to 100% by weight of propylene-based resin (X) having a die swell ratio of 1.8 or more, and is different from the propylene-based resin (X). The film which uniaxially stretched the resin composition containing 80 to 0 weight% of olefin resin (Y) can be mentioned. The die swell ratio is preferably 2 to 4, more preferably 2 to 3. The die swell ratio here is a value obtained by measuring the diameter of the cross section of the extrudate when measuring the melt flow rate according to the method of condition 14 of JIS K7210 and dividing this by the diameter of the orifice. Here, the cross section of the extrudate means a cross section perpendicular to the extruding direction of the extrudate. When the cross section is not a perfect circle, the average value of the maximum value and the minimum value of the diameter of the cross section is determined as the cross section of the extrudate. The diameter of

  The propylene-based resin used here is a resin having an isotactic polypropylene crystal structure. A thermoplastic propylene polymer resin containing 50% by weight or more of repeating units derived from propylene is preferable. A propylene homopolymer, a copolymer of propylene and an α-olefin having 2 to 10 carbon atoms (excluding propylene). More preferred are polymers or copolymers of propylene and at least one other monomer. Examples of the α-olefin include ethylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene and 1-decene. Examples of other monomers include conjugated dienes (butadiene, isoprene, etc.).

  The propylene-based resin (X) is produced by a polymerization method including a step of producing a crystalline propylene polymer portion having an intrinsic viscosity of 5 dl / g or more and a step of producing a crystalline propylene polymer portion having an intrinsic viscosity of less than 3 dl / g. Propylene polymer obtained, the content of the crystalline propylene polymer portion having an intrinsic viscosity of 5 dl / g or more in the propylene polymer is 0.05 wt% to 35 wt%, Particularly preferred are those having an intrinsic viscosity of less than 3 dl / g and a molecular weight distribution of less than 10.

  The olefin resin (Y) is a thermoplastic resin obtained by homopolymerizing an olefin, or a thermoplastic resin obtained by copolymerizing different olefins or copolymerizing an olefin and another monomer. Examples of the olefin include ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene and 1-decene. Examples of the other monomer include conjugated dienes (for example, butadiene and isoprene). Examples of the olefin resin include ethylene resin, propylene resin, butene resin, poly (4-methyl-1-pentene) resin, a mixture of these resins, and recycled resins thereof.

<Outermost layer>
(Configuration of outermost layer)
The outermost layer of the packaging material of the present invention is made of a heat-resistant flexible sheet.
The heat resistance here means that the melting point is 10 ° C. or higher than that of the innermost high-pressure method low-density polyethylene. The flexible sheet refers to a sheet that does not crack or crack when bent.

(Heat resistant flexible sheet)
A thermoplastic resin film can be used as the heat resistant flexible sheet. For example, known films such as various polyethylene resins, ethylene copolymer resins, polypropylene resins, propylene copolymer resins, polyvinyl chloride resins, polyvinylidene chloride resins, polyamide resins, polyacrylonitrile resins, polycarbonate resins, polyester resins, and the like These modified resin films or these uniaxial or biaxially stretched films can be used. Triacetate film, cellophane, regenerated cellulose film, EVOH (Eval) resin film, paper, synthetic paper, non-woven fabric and the like can also be used.

Particularly preferred heat-resistant flexible sheets are various papers having a basis weight of 20 to 400 g / m ² that do not adversely affect the photographic photosensitive material (spent paper, recycled paper, unbleached kraft paper, semi-bleached kraft paper, bleached kraft paper, Base paper, kurpack paper, duo-stress paper, white paperboard, photographic base paper, high-quality paper, medium-quality paper using high-yield pulp, pure white roll paper, coated paper, imitation paper, glassine paper), non-woven fabric, and synthetic paper It is an axially stretched thermoplastic resin film. These heat-resistant flexible sheets preferably contain a conductive material, which will be described later, in order to prevent the occurrence of static marks in the photographic photosensitive material.

  In addition, these heat-resistant flexible sheets can be used alone or in combination of two or more, and the melting point is higher by 10 ° C. or more than the polyolefin resin film used as the heat seal layer. This is preferable from the viewpoint of preventing the tearing and improving the appearance. Particularly preferred is a biaxially stretched thermoplastic resin film having a thickness of preferably 5 to 70 μm, more preferably 7 to 50 μm, and particularly preferably 10 to 35 μm.

<Inner layer>
(Configuration of innermost layer)
The innermost layer of the packaging material of the present invention comprises a light-shielding heat seal layer containing LDPE. The resin constituting the innermost layer of the packaging material of the present invention is preferably composed only of LDPE.

(LDPE)
LDPE typically can be obtained by polymerizing in the presence of a radical polymerization catalyst under a high pressure ethylene such as oxygen and a high temperature of ^{180~200 ℃ 1000~2000atm (1x10 8 ~2x10 8} Pa). LDPE is generally called high pressure polyethylene. The density of LDPE is lower than that of high density polyethylene (HDPE) (0.95 g / cm ³ ), and is usually 0.93 g / cm ³ or less. In addition, the LDPE referred to in the present invention does not include so-called linear low density polyethylene L-LDPE.

(Light shielding material)
The light shielding property of the innermost layer can be imparted by incorporating a light shielding material. Examples of the light shielding material include an inorganic light shielding material and an organic light shielding material.
Inorganic light-shielding substances include oxides (silica, diatomaceous earth, alumina, titanium oxide, iron oxide, zinc oxide, magnesium oxide, antimony oxide, barium ferrite, strontium ferrite, beryllium oxide, pumice, pumice balloon, alumina fiber, etc. ), Hydroxide (aluminum hydroxide, magnesium hydroxide, basic magnesium carbonate, etc.), carbonate (calcium carbonate, magnesium carbonate, dolomite, dawsonite, etc.), (sulfur) sulfate (calcium sulfate, barium sulfate, ammonium sulfate, And calcium sulfite) and silicates (talc, clay, mica, asbestos, glass fiber, glass balloon, glass beads, calcium silicate, montmorillonite, bentonite, etc.). Examples of carbon include carbon black, graphite, carbon fiber, and carbon hollow sphere. In addition, iron powder, copper powder, lead powder, tin powder, stainless steel powder, pearl pigment, aluminum powder, molybdenum sulfide, boron fiber, silicon carbide fiber, brass fiber, potassium titanate, lead zirconate titanate, zinc borate , Barium metaborate, calcium borate, sodium borate, aluminum paste, talc and the like.

  Organic light-shielding substances include wood flour (pine, straw, sawtooth, etc.), cereal fibers (almonds, peanuts, fir shells, etc.), various colored fibers (eg cotton, jute, paper strips, cellophane pieces, nylon fibers) , Polypropylene fiber, starch, aromatic polyamide fiber) and the like.

  The light-shielding substance preferably has an average particle diameter measured by an electron microscope of 5 to 10,000 nm, more preferably 9 to 5000 nm, still more preferably 13 to 2000 nm, and 15 to 1000 nm. Particularly preferred. The refractive index measured by the Larsen oil immersion method is preferably 1.45 or more, more preferably 1.5 or more, further preferably 1.55 or more, and 1.6 or more. Is particularly preferred. The DBP oil absorption measured by the oil absorption A method of JIS K6221 is preferably 10 to 800 ml / 100 g, more preferably 15 to 600 ml / 100 g, still more preferably 20 to 400 ml / 100 g. It is especially preferable that it is 25-200 ml / 100g.

  If it is a light-shielding substance that satisfies the above characteristic values, it has good dispersibility in the thermoplastic resin composition containing LDPE, has excellent light-shielding ability, and does not adversely affect the photographic performance of the photosensitive material. Among these light-shielding substances, carbon black is most preferable because it can reduce the amount of bleed out of lubricants and antioxidants, is inexpensive, has excellent light-shielding ability, and has little adverse effect on the photographic performance of photosensitive materials. .

  There are furnace carbon black, channel carbon black, thermal carbon black, acetylene carbon black, etc. as classification according to the production method of carbon black, and any of these may be used, but among these, photographic adverse effects (fogging, Furnace carbon black is most preferred from the standpoints of low decrease in sensitivity or increase in sensitivity, etc., and improvement in light shielding properties.

  In the present invention, carbon black having a particle diameter of 5 to 350 nm, a DBP oil absorption of 10 to 350 ml / 100 g, and a refractive index of 1.45 or more can be particularly preferably used. In order to further suppress the adverse effect on the photographic performance of the photosensitive material, the sulfur content measured by ASTM D-1619 measurement method is preferably 1.0% by weight or less, more preferably 0.8% by weight or less, and still more preferably. It is preferable to use carbon black of 0.6% by weight or less, particularly preferably 0.4% by weight or less.

  The content of the light-shielding substance such as carbon black in the layer is generally 0.05 to 40% by weight, preferably 0.1 to 35% by weight, particularly preferably 0.15 to 30% by weight, and most preferably 0.00. 2 to 25% by weight. A light-shielding substance such as carbon black may be added not only to the innermost layer but also to other layers.

  Preferred examples of commercially available carbon black include acetylene black (Denka Black) manufactured by Electrochemical and carbon blacks # 20 (B), # 30 (B), # 33 (B), and # 40 (B) manufactured by Mitsubishi Kasei. , # 41 (B), # 44 (B), # 45 (B), # 50, # 55, # 100, # 600, # 950, # 1000, # 2200 (B), # 2400 (B), MA8 , MA11, MA100, Show Black Cabot Show Black N134, N110, N220, N234, N219, N339, N330, N326, N330T, N351, MAF, N550, SRF, etc., Cabot Black Pearls 2, 46, 70, 71, 74, 80, 81, 607, etc. Regal 300, 330, 400, 660, 991, SRF-S, etc., Vul can3, 6, etc., Sterling 10, SO, V, S, FT-FF, MT-FF, etc., Ashland Chemical's United R, BB, 15, 102, 3001, 3004, 3006, 3007, 3008, 3009, 3011, 3012, XC-3016, XC-3017, 3020 and the like.

<Other layers>
In addition to the outermost layer, the intermediate layer, and the innermost layer, the packaging material of the present invention may be provided with an arbitrary layer within a range that does not impair the effects of the present invention. For example, an adhesive layer, an anchor coat layer, an aluminum layer, or the like may be provided.

<Photosensitive material, photosensitive thermosensitive material, thermosensitive material>
The type of photosensitive material, photosensitive thermosensitive material or thermosensitive material to be packaged with the packaging material of the present invention is not particularly limited. For example, a silver halide photographic light-sensitive material, a non-silver halide photographic light-sensitive material, a diazo photographic light-sensitive material, a photosensitive resin, a light fixing type heat-sensitive material, a heat-developable light-sensitive material, a light-sensitive heat-sensitive material, or a developer, a fixing solution, Examples thereof include photosensitive materials whose quality is deteriorated by light or moisture, such as dyes. Further, the shape of the photosensitive material is not particularly limited, but it can be particularly preferably used for a sheet-like photosensitive material.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

<Material>
The layer structure of the packaging material used in the examples and comparative examples is described below. In the following description, PE is polyethylene, LDPE is low density polyethylene, black LDPE is high pressure method low density polyethylene containing carbon black, and black L-LDPE is linear low density polyethylene containing carbon black.
Example 1 Bleached Kraft Paper 60 g / Laminated PE 13 μm / Al 7 μm / Laminated PE 13 μm / Mitsui Noblen Film 20 μm / Laminated PE 13 μm / Black LDPE 40 μm
(Example 2) Bleached kraft paper 60 g / Laminated PE 13 μm / Al 7 μm / Laminated PE 13 μm / Kalariyan Y 18 μm / Laminated PE 13 μm / Black LDPE 40 μm
(Comparative Example 1) Bleached kraft paper 60 g / Laminated PE 13 μm / Al 7 μm / Laminated PE 13 μm / Black LDPE 40 μm
(Comparative example 2) Bleached kraft paper 60 g / Laminated PE 13 μm / Al 7 μm / Laminated PE 13 μm / Black L-LDPE 40 μm
(Comparative Example 3) Bleached kraft paper 60 g / Laminated PE 13 μm / Al 7 μm / Laminated PE 13 μm / Toyobo Pyrene Film-OTP2002 20 μm / Laminated PE 13 μm / Black LDPE 40 μm

<Example 1>
As a heat-resistant flexible sheet, bleached kraft paper with a basis weight of 60 g / m ² and 7 μm thick aluminum foil are bonded together by high pressure low density polyethylene (LC600A manufactured by Nippon Polychem Co., Ltd.) as an adhesive, and laminated with film A. Obtained. High-pressure low-density polyethylene of 70 μm thickness obtained by kneading 3% by mass of 20 μm-thick longitudinally uniaxially stretched polypropylene film (Mitsui Chemicals Bratec Co., Ltd., Mitsui Noblen film) and furnace-type carbon black as the innermost layer. A film B was obtained by pasting (by Nippon Unicar Co., Ltd., DFD-0111) by a high pressure method low density polyethylene (manufactured by Nippon Polychem Co., Ltd., LC600A) by an extrusion laminating method. Film A and film B were bonded together by an extrusion laminating method using high-pressure low-density polyethylene (manufactured by Nippon Polychem Co., Ltd., LC600A) as an adhesive to obtain a packaging material for a photosensitive material and / or a heat-sensitive material.

<Example 2>
Packaging for a photosensitive material and / or a heat-sensitive material in the same manner as in Example 1 except that a 18 μm-thick lateral uniaxially stretched high-density polyethylene film (manufactured by Denki Kagaku Kogyo Co., Ltd., Calaryan Y) is used as the intermediate layer. Obtained material.

<Comparative Example 1>
As a heat-resistant flexible sheet, bleached kraft paper with a basis weight of 60 g / m ² and 7 μm thick aluminum foil are bonded together by high pressure low density polyethylene (LC600A manufactured by Nippon Polychem Co., Ltd.) as an adhesive, and laminated with film C. Obtained. The obtained film C and 70 μm-thick high-pressure low-density polyethylene (Nihon Unicar Co., Ltd., DFD-0111) kneaded with 3 mass% of furnace-method carbon black as the innermost layer were mixed with high-pressure low-density polyethylene (Nippon Polychem ( Co., Ltd., LC600A) was used as an adhesive and bonded together by an extrusion laminating method to obtain a packaging material for a photosensitive material and / or a heat-sensitive material.

<Comparative example 2>
Packaging for photosensitive material and / or heat-sensitive material in the same manner as in Comparative Example 1 except that 70 μm thick C-6 linear low density polyethylene kneaded with 3% by mass of furnace method carbon black was used as the innermost layer. Obtained material.

<Comparative Example 3>
Packaging for photosensitive material and / or heat-sensitive material in the same manner as in Example 1 except that a biaxially stretched polypropylene film (Toyobo Co., Ltd., Toyobo Pyrene Film-OTP2102) having a thickness of 20 μm was used as the intermediate layer. Obtained material.

<Evaluation method>
(1) Tensile strength Measured according to JIS K 7127 at a tensile speed of 10 mm / min.
(2) Gervo test According to the US military standard MIL-B181, the number of pinholes in 100 tests was measured.
(3) Puncture strength Measured according to JIS Z 1707.
(4) Drop strength In the method described in Example 3 of JP-A No. 2003-337395, photothermographic photosensitivity using the packaging materials of Examples 1 and 2 and Comparative Examples 1 to 3 of the present application as hermetic packaging sheets. A packaging material was obtained.
The obtained package was dropped by changing the drop height by the method of JIS Z 0202, and the drop height at which the packaging material started to break was defined as the drop strength.
(5) Openability Ease of opening when the packaging body obtained in (4) above was held by hand in the MD direction and the TD direction was evaluated in the following two stages.
○ It was possible to tear by hand.
× Could not be torn by hand.
Moreover, the presence or absence of linearity of opening when opened was also confirmed.

<Evaluation results>

  The packaging material of the present invention can be used for packaging various types of photosensitive materials. In particular, it can be preferably used for packaging a sheet-shaped photosensitive material, a sheet-shaped photosensitive thermosensitive material, or a sheet-shaped thermosensitive material, and can also be preferably used for packaging a photosensitive material having a relatively heavy weight such as an X-ray film. . Therefore, the packaging material of the present invention is expected to be applied in various fields and has high industrial applicability.

Claims (2)

  It is a packaging material for a photosensitive material, a photosensitive thermosensitive material or a thermosensitive material having an intermediate layer between an outermost layer composed of a heat-resistant flexible sheet and an innermost layer composed of a light-shielding heat-seal layer containing high-pressure low-density polyethylene. A packaging material in which the intermediate layer is a uniaxially stretched thermoplastic resin layer having a ratio of the tensile strength in the vertical direction to the tensile strength in the horizontal direction according to JIS K 7127 of 4 to 50 times.   The packaging material for a photosensitive material, a photosensitive thermosensitive material or a thermosensitive material according to claim 1, wherein the heat-resistant flexible sheet is paper.