Stock material or miscellaneous articles – Structurally defined web or sheet – Including components having same physical characteristic in...
Patent
1995-08-03
1998-03-03
Thibodeau, Paul J.
Stock material or miscellaneous articles
Structurally defined web or sheet
Including components having same physical characteristic in...
428215, 428323, 428339, 428480, 428910, 430533, B32B 2736, B32B 2706, G03C 1795, G03C 181
Patent
active
057232083
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/JP94/00180, filed Feb. 7, 1994, published as WO95/16223 Jun. 15, 1995.
TECHNICAL FIELD
The present invention relates to a laminated base film for a photographic film. More specifically, it relates to a laminated base film for a photographic film, comprising a first layer of a polyethylene-2,6-naphthalenedicarboxylate and a second layer of a polymer composition containing a 2,6-naphthalenedicarboxylate unit and an ethylene unit in a total amount of at least 70% by weight.
TECHNICAL BACKGROUND
Polyester films, particularly, films of polyethylene terephthalate, polyethylene-2,6-naphthalenedicarboxylate and a polyester composed mainly of these, have excellent properties in heat resistance, chemical resistance and mechanical properties so that they are used in many fields of magnetic tapes, photographs, electric, packages and drawings.
However, although polyester films have excellent mechanical properties, transparency and dimensional stability, they elongate and contract to a less degree relative to a change in temperature than a triacetylcellulose film which is generally used as a base for a photographic film. Therefore, when a photosensitive emulsion containing, as a main binder, a hydrophilic polymer such as gelatin is applied, they undergo curling due to the difference in elongation and contraction ascribed to the large elongation and contraction which the emulsion layer undergoes with a change in humidity. It is therefore a pending serious problem to overcome a curling-induced decrease in working efficiency in enlargement and printing.
In recent years, pocket cameras which are easy to carry about and handy are put to practical use, and it is therefore demanded to decrease the thickness of a photographic film for further miniaturize the cameras. As properties of the film for the above purpose, the film is required to have high mechanical strength, particularly high breaking strength. For this purpose, a polyethylene-2,6-naphthalenedicarboxylate film having excellent mechanical strength over a polyethylene terephthalate film is promising. However, polyethylene-2,6-naphthalenedicarboxylate has a defect in that it is liable to undergo interlaminar peeling in the thickness direction presumably because the polymer has a stiff structure.
Proposals for improving the curling properties by easing the curing of formed curl or proposals for improving the curling properties by decreasing the curling properties to prevent curling have been so far made as follows.
U.K. Patent 1,476,343 of which the priority is based on the two patent applications of Japanese Laid-open Patent Publication No. 50-16783 and Japanese Patent Publication No. 56-53745 discloses an oriented heat-set laminated film comprising a first crystalline aromatic polyester layer (A) formed on one surface of a laminate, a second crystalline aromatic polyester layer (B) formed on the other surface of the laminate and optionally a third crystalline aromatic polyester layer (C) formed between the above (A) layer and (B) layer, in which the aromatic polyester constituting the (A) layer has an intrinsic viscosity of 0.35 to 1.0, and the aromatic polyester constituting the (B) layer has an intrinsic viscosity of 0.37 to 1.0, the intrinsic viscosity being higher than that of the above aromatic polyester constituting the (A) layer by 0.02 to 0.5. It is disclosed that the above laminated film undergoes curling with the (A) layer outside and the (B) layer inside and gives a photographic film of which the curling is offset by the contraction of a photosensitive layer formed by applying the photosensitive layer to the (A) layer side.
Further, the following proposal for a base film for a photographic film, formed of a single layer, has been made.
Japanese Laid-open Patent Publication No. 50-81325 discloses a photographic film having, as a substrate film, a biaxially oriented polyethylene-2,6-naphthalenedicarboxylate film in which the ratio of Young's moduli in the longitudinal and transverse directions is in the range of 0.9 to 1.
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Furuya Koji
Nagai Tsuyoshi
Suzuki Kenji
Chen Vivian
Teijin Limited
Thibodeau Paul J.
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