Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Structurally defined
Patent
1994-10-12
1996-03-05
Neville, Thomas R.
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Structurally defined
430496, 430531, 430533, 430501, 428480, 428913, 428143, 428213, 428220, 528272, 528298, G03C 302
Patent
active
054966884
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a base film for a photographic film. More specifically, it relates to a base film for a photographic film, which has anti-curling properties, transparency and lubricity and which is formed of polyethylene-2,6-naphthalenedicarboxylate as a raw material.
TECHNICAL BACKGROUND
A biaxially oriented polyethylene-2,6-naphthalenedicarboxylate film is excellent in mechanical properties, thermal properties and electric properties, and is hence studied for use in various fields. It has been put to practical use in the fields of a magnetic recording medium and electric insulation.
As one of uses of the above film, it is used in the field, for example, of photographic photosensitive materials. These photosensitive materials are largely classified into films used in the form of a sheet such as an X-ray film, a film as a printing plate and a cut film and films used in the form of a roll typified by a color or black-and-white negative film having a width of 35 mm or less. This negative film is encased in a film cartridge and the cartridge is placed in the holder of a general camera when used for taking pictures.
A biaxially oriented polyester film formed of polyethylene terephthalate is mainly used as a base for films in the form of a sheet. Further, a film formed of a cellulose-based polymer typified by triacetyl cellulose (to be sometimes referred to as TAC hereinafter) is used as a base for films in the form of a roll.
A TAC film has its characteristic features in freedom from optical anisotropy, high transparency and the property of removal of curling after developing treatment, and in particular, the excellence in the property of removal of curling is said to be a feature that does not belong to a film of any other material. Since, however, the production of the TAC film uses an organic solvent, it is necessary to take care to recycle the solvent completely for preventing the environmental pollution. In particular, the issue of environmental destruction is attracting attention in recent years, and there is a growing tendency to decrease or avoid the use of an organic solvent which may cause an environmental pollution.
On the other hand, a polyethylene terephthalate film is a film that can be formed by a melt extrusion method without any organic solvent, and a polyethylene terephthalate film is partly started to be used as a base film for a photosensitive film for photography.
However, a polyethylene terephthalate film has a problem in that it undergoes curling (curling tendency) and that it is difficult to remove the curling. That is, a base film for a photosensitive material for photography is once taken up and stored in the form of a roll, and thereafter the film is taken out of the storage, cut to a proper size and used in the form of a flat sheet such as an X-ray film, a printing plate or a cut film. In the case of a rolled film, after taking pictures, development and fixing, a negative film encased in a film cartridge in the form of a roll is cut to a predetermined length and inserted into a film album, and the film is stored in the form of sheets. However, a polyethylene terephthalate film has a problem in that it retains the curling which has occurred when the film has been taken in the form of a roll, and it curls after cut in the form of sheets.
For overcoming the curling by easing the removal of the curling which has occurred, or by decreasing the curling tendency to prevent the curling, the following proposals have been made.
Japanese Laid-open Patent Publication No. 16,783/1975 discloses a biaxially oriented laminated polyester film formed of two polyester layers, in which the intrinsic viscosity of each polyester layer is in the range of 0.35 to 1.0 but the difference between the intrinsic viscosity of one polyester layer and that of the other polyester layer is in the range of 0.02 to 0.5.
The above laminated polyester film seeks to overcome the curling by causing a curling based on a shrink stress difference between the front surface layer and the op
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Japanese Laid-Open Patent Publication No. 95,374/1975 abstract.
Japanese Laid-Open Patent Publication No. 109,715/1975 abstract.
EP 334 367 A-abstract. (corr. to Japanese Laid Open Publ. 244,446/1989).
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Katoh Kohtaro
Okamoto Hiroshi
Saitoh Kazuyoshi
Suzuki Kenji
Tomita Hiroshi
Neville Thomas R.
Teijin Limited
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