JPH0341815B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a protective sheet for photographic film. In recent years, with the advancement of photographic systems including cameras and photosensitive films, there has been a demand for sheet photosensitive films in addition to the conventionally commonly used take-up roll type photosensitive films. The easiest way to store and transport such sheet-like photosensitive film is to store it in a synthetic resin molded product 1 as shown in FIG. It is necessary to store the molded product in a way that does not allow light to enter from the outside, and it is also necessary to prevent fogging caused by static electricity generated by shaking inside the molded product during transportation. Therefore, it is necessary to mix conductive carbon black such as acetylene black into the synthetic resin molded product 1. However, this conductive carbon black is extremely expensive compared to carbon black used for coloring or light shielding purposes. Therefore, as shown in FIG. 2, the present inventors created a plastic sheet 3 with conductive carbon black coated on the surface between a synthetic resin molded product 1 mixed with light-shielding carbon black and a photosensitive film 2. It has been discovered that by interposing , it is possible to reduce the amount of expensive conductive carbon black used, and to obtain sufficient physical properties. The properties required for this plastic sheet 3 are as follows (a) to (g). (b) The surface layer of plastic sheet 3 and the photosensitive emulsion surface should not adhere. (b) The adhesive strength between the layer 34 on the surface of the plastic sheet 3 and the base material 31 is sufficient so that even if the layer on the surface of the plastic sheet 3 adheres to the photosensitive emulsion, it will not peel off from the base material 31. (c) The surface of the plastic sheet 3 should have good slip properties so that the surface of the photosensitive film is not damaged by shaking during transportation. (d) The photosensitive emulsion used for the layer 34 on the surface of the plastic sheet 3 should not cause fogging. (E) Polystyrene is selected for the synthetic resin molded product 1 because it has a low shrinkage rate during injection molding and good shape stability, and it must have weldability to this polystyrene. (f) Static electricity generated between the synthetic resin molded product 1 and the plastic sheet 3 due to the vibration during transportation can be removed. (g) The plastic sheet 3 must be rigid. In order to address these demands, the applicant:
Patent application No. 179041 was filed. This Japanese Patent Application No. 58-179041 discloses that the surface of a polyester film having a conductive and heat-sealable layer (back layer) on its back surface is preferably subjected to surface corona discharge treatment, and then polyester and polyvinylidene The binder resin is a mixture of the following in a weight ratio of 10:1 to 1:10, to which a matting agent and a slipping agent are added, and if necessary, a titanate coupling agent is further added. This patent describes a photographic photosensitive film protective sheet characterized by having a surface layer), the back layer corresponding to 33 in FIG. 3 of the drawings of this case, and the surface layer corresponding to 34 as well. And, the surface layer of Japanese Patent Application No. 179041/1986 is the above-mentioned
It satisfies requirements (a) to (d), and the back layer is (e)(
f)
The polyester base material satisfied the requirement (g). By the way, this Japanese Patent Application No. 179041/1980 discloses a material with a styrene content of 95% to which carbon black, a part of which is conductive carbon black, is added as a back layer.
The use of a layer of styrene-butadiene copolymer that is ~60% is described. This is because if the styrene content is lower than 60%, the solubility of the styrene-butadiene copolymer in solvents such as toluene becomes poor, making coating relatively difficult. However, when the present inventors continued to study further,
It was discovered that the solubility of styrene-butadiene copolymers with a styrene content of 50% or less can be solved by changing the type and amount of solvent, and that using this solution can further improve the weldability of polystyrene to molded products. did. The present invention was made based on this discovery, namely, a sheet comprising a base film made of a plastic film with a layer having slip properties on the surface, and a back layer that can be welded to the inner surface of a polystyrene molded product on the back surface. After providing an undercoat layer as necessary on the back side of the base film,
This is a photographic photosensitive film protective sheet characterized by being provided with a solvent-soluble styrene-butadiene copolymer layer having a styrene content of 50% or less mixed with conductive carbon black. FIG. 3 is a sectional view of the photographic photosensitive film protective sheet 3 of the present invention, in which 31 is a base film made of plastic film, 32 is an undercoat layer, and 33 is a styrene-butadiene mixture mixed with conductive carbon black. Polymer layer (back layer),
34 is a layer having conductivity and slip property (surface layer)
It shows. As the base film 31, a polyester film is preferred, but in addition to this, plastic films such as polyamide and cellulose acetate can be used. This base film 31 needs to have a thickness of 40 to 100 μm so that it will not break during heat-sealing to the molded product 1. The undercoat layer 32 is provided to improve the adhesion between the base film 31 and the back layer 33, and is made of, for example, amorphous saturated polyester resin or polyurethane resin, and has a thickness of 5 to 50%.
It is 15μ. As mentioned above, the back layer 33 is made of a styrene-butadiene copolymer containing conductive carbon black and having a styrene content of 50% or less, but in addition to the conductive carbon black, it also contains a matting agent and a light shielding carbon black. can also be included. However, its surface resistance must be 10 ⁶ Ω or less, and
The optical density of the entire protective film 3 needs to be 4 or more. To achieve this, the total amount of conductive carbon black and light-shielding carbon black is 7
~25% is desirable. Further, the thickness of this back layer 33 is desirably 5 to 15 microns. Further, the surface layer 34 may be the same as the surface layer described in Japanese Patent Application No. 179041/1982, that is, polyester and polyvinylidene chloride in a weight ratio of 10:1 to 10:1.
The binder resin is mixed at a ratio of 1:10, to which are added a matting agent and a slip agent, and if necessary, a titanate coupling. All of these layers 32, 33, and 34 can be obtained by coating with a paint using a solvent and a suitable coating method such as gravure coating or roll coating. There is also an emulsion type of styrene-butadiene resin, but this is emulsion polymerization and contains various additives such as activators and emulsion stabilizers such as hydrazine, which cause fog to photographic emulsions. As mentioned above, in the present invention, it is desirable to dissolve the styrene-butadiene resin in a solvent such as aromatic hydrocarbons, ertels, ketones, etc. and coat the resin. The present invention is a protective sheet as described above, which is used by being welded to the inner surface of a synthetic resin molded product 1 made of polystyrene. Welding does not need to be performed over the entire surface, but may be performed partially. The present invention will be explained below with reference to Examples. Example 1 The following coating material 1 was applied to one side (back side) of a polyester film having a thickness of 50 μm so that the thickness after drying was 5 μm to form an undercoat layer. Γ Paint 1 Byron #500 (manufactured by Toyobo Co., Ltd.; amorphous saturated polyester solution) 1000 parts by weight Denka Black (manufactured by Denki Kagaku Kogyo Co., Ltd.; conductive carbon black) 50 parts by weight Homogenol L-18 (manufactured by Kao Atlas Co., Ltd.) Co., Ltd.; dispersion accelerator) 2.5 parts by weight After that, apply the following paint 2 on this undercoat layer.
was roll coated to form a back layer so that the thickness after drying was 15 μm. Γ Paint 2 Solprene T-406 solution (manufactured by Asahi Kasei Industries, Ltd.; styrene with 40% styrene and 60% butadiene)
Butadiene copolymer dissolved in toluene as a solvent. Solid content: 20%) 350 parts by weight Denka black 5 parts by weight Carbon black for light shielding (manufactured by Mitsubishi Chemical Industries, Ltd.)
5 parts by weight Thyroid 162 (manufactured by Fuji Davison Chemical Co., Ltd.; matting agent made of silicic acid powder) 8.3 parts by weight Aluminum oxide (manufactured by Kanto Chemical Co., Ltd.; matting agent)
1.7 parts by weight Ethyl acetate (organic solvent) 100 parts by weight After this, the opposite side (surface) of the polyester film was treated with corona discharge, and then the following paint 3 was applied.
The air knife coating method reduces the coating amount.
It was applied at a concentration of 1.2 g/m ² . Γ Paint 3 Eastman WD size (manufactured by Eastman Chemical Co., Ltd.; polyester aqueous dispersion, solid content 30%) 100 parts by weight Saran Latex L-511 (manufactured by Asahi Kasei Corporation; polyvinylidene chloride aqueous dispersion) , solids content 50
%) 300 parts by weight Polymethyl methacrylate powder dispersion (particle size 5μ, solid content 54%) 16.7 parts by weight Polyethylene powder dispersion (manufactured by Toyo Ink Mfg. Co., Ltd.; solid content 40%) 9 parts by weight Cyroid 978 (Fuji (manufactured by Davison Chemical; silicic acid powder, particle size 4μ) 0.37 parts by weight Nopcote PEM-17 (manufactured by San Nopco Co., Ltd.; polyethylene emulsion slip agent, solid content 40%)
21.3 parts by weight Then, a part of it was sealed by ultrasonic welding, and the sealing strength was measured. Further, the surface resistivity of the back surface of Film A and the optical density of Film A were measured. These measurement results are shown in Examples 2 to 2 described below.
4 and Comparative Example 1 are shown in Table 1. Example 2 Instead of Solprene T-406 solution of paint 2 of Example 1, Cauliflex TR-4122 (manufactured by Ciel Chemical Industry Co., Ltd.; 50% styrene component, butadiene component) was used.
Film B was prepared in the same manner as in Example 1 except for using a toluene solution of 50% styrene-butadiene copolymer, and its seal strength, surface resistivity, and optical density were measured. Example 3 Tuffprene A (manufactured by Asahi Kasei Industries, Ltd.; a toluene solution of a styrene-butadiene copolymer containing 40% styrene and 60% butadiene) was used instead of Solprene T-406 solution in paint 2 of Example 1. , otherwise produced film C in the same manner as in Example 1,
Its seal strength, surface resistivity, and optical density were measured. Example 4 Cauliflex KX-65 (manufactured by Ciel Chemical Industry Co., Ltd.; styrene component 28%, butadiene component 72%) was used instead of Solprene T-406 solution in paint 2 of Example 1.
A toluene solution of styrene-butadiene copolymer) was used to prepare Film D in the same manner as in Example 1, and its seal strength, surface resistivity, and optical density were measured. Comparative Example 1 K resin (manufactured by Philips; toluene solution of styrene-butadiene copolymer with 75% styrene component and 25% butadiene component) was used instead of Solprene T-406 solution in coating 2 of Example 1. Film E was prepared in the same manner as in Example 1, and its seal strength, surface resistivity, and optical density were measured.

[Table] As can be seen from the above results, the styrene-butadiene copolymer to which conductive carbon black has been added improves its weldability to polystyrene molded products as the styrene content decreases. It has virtually no effect on resistance or optical density.

[Brief explanation of drawings]

1 and 2 are sectional views of a synthetic resin molded product containing a photographic photosensitive film, and FIG. 3 is a sectional view of a protective sheet for the photographic photosensitive film. 1...Synthetic resin molded product, 2...Photosensitive film,
3... Protective sheet, 31... Base film, 32
... Undercoat layer, 33 ... Back layer, 34 ...
...surface layer.

Claims (1)

[Claims] 1. In a photographic photosensitive film protective sheet consisting of a base film made of a plastic film with a layer having slip properties on its surface, and a back layer that can be welded to the inner surface of a polystyrene molded product on the back side, A photographic light-sensitive film characterized in that, after providing an undercoat layer according to the requirements, a back layer consisting of a solvent-soluble styrene-butadiene copolymer with a styrene content of 50% or less mixed with conductive carbon black is provided. protective sheet.