Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Identified backing or protective layer containing
Reexamination Certificate
1999-05-28
2001-03-06
Baxter, Janet (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Identified backing or protective layer containing
C430S533000, C428S480000
Reexamination Certificate
active
06197487
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a silver halide photosensitive photographic material and a thermally developable photosensitive photographic material which are produced on and employed from a wound roll, and a support employed in these photosensitive photographic materials, and specifically to a support for photosensitive photographic materials, which tend not to result in roll-set curl, and exhibits excellent workability.
BACKGROUND OF THE INVENTION
When photosensitive photographic materials are employed in various sizes, from the viewpoint of ease of handling and space saving, the required amount is often taken from the material in a roll form and subsequently employed. Specifically, in the printing and plate making field, a large amount of materials employed are in the form of rolled film.
When the film is employed in such a manner, in terms of workability, a major problem is roll-set curl of the film. For example, problems occur such that during continuous cutting of the film employing an automatic roll cutter, when the roll-set curl is severe, cut film sheets do not pile well; when exposure is carried out upon bringing a sheet of film into contact with an original, insufficient contact and similar problems occur.
In recent years, along with the size reduction of apparatuses, the size of rolled film has tended to decrease, and the size of roll cores has also decreased. Film exhibiting less roll-set curl is thus highly desirable.
As methods to minimize this roll-set curl, for example, Japanese Patent Publication Open to Public Inspection No. 51-16358 proposes that as a method to minimize the roll-set curl of polyester film, thermoplastic film is subjected to thermal treatment at Tg−5° C. to Tg−30° C. for 0.1 to 1,500 hours. Further, Japanese Patent Publication Open to Public Inspection No. 6-35118 proposes that after subbing polyester film having Tg of 90 to 200° C., the resulting film is subjected to thermal treatment at 50° C. to Tg for 0.1 to 1,500 hours.
However, in these methods, thermal treatment at a relatively low temperature for a long period is required and is not efficient in terms of production. Furthermore, when a long roll of film is produced, it must be subjected to thermal treatment for a long period as an intermediate product in the wound-roll state and a problem occurs, such that roll-set curl is caused due to the diameter of the wound core. When it is employed to produce a silver halide photosensitive photographic material in the rolled state, problems occur such that the roll-set curl, previously caused by the above mentioned thermal process, makes it impossible to exhibit sufficient advantages.
These problems are not so serious for silver halide photosensitive photographic materials which are wound on a relatively small core, while they are particularly serious for those such as graphic art materials, etc. which are wound on a relatively large core.
Furthermore, when thermal treatment is carried out in the rolled state, the thermal treatment process has been limited due to problems such as the degradation of flatness, and adherence between contacting surfaces.
SUMMARY OF THE INVENTION
In view of the above-mentioned problems, an object of the present invention is to provide a photographic support which makes it possible to produce a photosensitive photographic material which tends not to result in roll-set curl and exhibits excellent workability for the case of wound photosensitive photographic materials, such as graphic art materials, etc., which are wound on a core having a relatively large diameter.
The present invention and embodiments relevant thereto will now be described.
The support of the present invention is composed of plastic film in which polyethylene naphthalate is the major component, and is prepared by thermally treating said film in the range of not less than its Tg of said film to no more than its Tg plus 55° C. The duration of the thermal treatment is preferably between 5 and 60 minutes.
The thermal treatment is preferably carried out after a sublayer is coated and subsequently dried. The thermal treatment is preferably carried out in such a manner that the plastic film is heated up to a high temperature which does not exceed its Tg+55° C. and is then cooled.
The plastic film is composed of preferably a mixed resin comprising two or more types of polyester resins having different property or component. The plastic film is composed of preferably a mixed resin comprising two or more types of polyester resins having an intrinsic viscosity of 0.3 to 1.2, as well as an intrinsic viscosity difference of 0.2 to 1.0.
At least one of the polyester resins is preferably polyethylene-2,6-naphthalate.
It is preferred that a polyester resin having a lower intrinsic viscosity is incorporated in an amount of 10 to 80 weight percent. Polyester resin having the highest intrinsic viscosity is preferably in an amount of 20 to 90 wt %.
The photographic support may be prepared by mixing at least two types of polyester resins of polyethylene-2,6-naphthalate having different properties.
The ratio D
145
/D
135
, that is, the ratio of a tan &dgr; value (D
145
) at 145° C., based on dynamic viscoelasticity measurement of the film to a tan &dgr; value (D
135
) at 135° C., based the same measurement is preferably between 0.8 and 1.4.
Film having a specific tan delta may be obtained, for example, by controlling the state of film crystallization or the physical properties of the polymers incorporated into the film. Control of the film crystallization may be carried out by varying the conditions of temperature, cooling rate, and heating rate in the thermal treatment conditions. Furthermore, in order to vary the physical properties, there are methods such as mixing polyesters having different physical properties and appropriately varying the molecular weight and intrinsic viscosity, etc.
Preferred are mixed polyesters consisting of at least two of the same types, or different types of polyesters which exhibit, by at least 30 minutes, the semicrystallizing time difference at 250° C. obtained by the measurement employing a differential scanning calorimeter are preferred.
The semicrystallizing time difference of the resins is preferably at least 5 minutes.
One example of combinations of mixed resins is a polyester resin prepared employing a germanium compound as a polymerization catalyst and a polyester resin prepared by employing an antimony compound as a polymerization catalyst.
DETAILED DESCRIPTION OF THE INVENTION
The thermal treatment of the present invention is different from the conventionally well known annealing treatment which is carried out at a temperature of no more than the Tg of the support in the wound state, and is a method in which the roll-set curl is not likely to be caused by carrying out thermal treatment at a temperature of at least its Tg.
Thermal treatment is preferably carried out after the plastic film is biaxially stretched. It is understood that when biaxially stretched, the plastic film undergoes partial crystallization, and when such film is heated at a temperature exceeding its Tg, some of the crystal structure is relaxed and due to that, the roll-set curl is minimized.
In order to relax the crystallized structure so that it is not lost, it is critical to choose the optimal temperature and duration. Heating is carried out to a temperature exceeding Tg, and is preferably carried out to a temperature which exceeds the Tg by 5° C. The treatment time is dependent on the heating temperature, and at a high temperature, the treatment time is preferably short.
The function of conventional so-called annealing is not to relax the crystal structure but is rather to fix the same. The annealing is carried out at a temperature below its Tg and the crystal structure is unlikely lost. Therefore, the annealing treatment is carried out over a relatively long duration.
In the present thermal treatment, heating is carried out to a temperature exceeding the Tg followed by cooling. The processing time denotes the durati
Ezure Hidetoshi
Kurachi Yasuo
Ohnuma Kenji
Takada Masahito
Baxter Janet
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Konica Corporation
Walke Amanda C.
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