US 3560288 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
Feb. 2, 1971 TAKESHI MKAMI METHOD OF MAKING A LAMINATED PHOTOGRAPHIC LIGHT SENS IT IVE ELEMENT Filed Dec. 28, 1967 FIG. I
INVENTOR TAKESHI MKAMI FIG. 2
ATTORNEYS United States Patent 3,560,288 METHOD OF MAKING A LAMINATED PHOTO- GRAPHIC LIGHT-SENSITIVE ELEMENT T alreshi Mikami, Kanagawa, Japan, assignor to Fuji Photo Film (10., Ltd., Kanagawa, Japan Filed Dec. 28, 1967, Ser. No. 694,180 Claims priority, application Japan, Dec. 28, 1966, 42 438 Int. Cl. B29c 23/00 [1.5. CI. 156-229 6 Claims ABSTRACT OF THE DISCLOSURE A method for coating both surfaces of a support suitable for photographic light-sensitive elements whereby one or more coating compositions are applied to continuously moving surfaces of cooling members, gelling said coatings by cooling, stripping the gelled layers from the cooling surfaces and adhering them to the surfaces of the support.
BACKGROUND OF THE INVENTION The present invention relates to a method of coating opposite sufaces of a support for preparing photographic light-sensitive elements. More particularly, the invention relates to a method of coating the opposite surfaces of a support for photographic light-sensitive elements in which two or more photographic layers such as silver halide emulsion layers and protective layers are applied to one surface of the support and, at the same time, one or more layers such as a backing layer are applied to the opposite surface of the support. Subsequently, according to the invention, the layers thus applied are dried simultaneously.
As a method of coating the opposite surfaces of a continuously travelling support, there has previously been employed a method whereby one or more coating compositions are applied to one surface of a support followed by drying and, thereafter, one or more coating compositions applied to the opposite surface thereof followed by drying. A method has also been proposed whereby the opposite surfaces of a support are coated in one step and, thereafter, the layers on the opposite surfaces dried simultaneously. The latter method is preferred over the former because of better operation efficiency and economy.
In the previously proposed methods wherein the opposite surfaces of a support are coated in one step and thereafter dried simultaneously, the surfaces of the support are generally coated with coating compositions in sol-like states by means of coating devices. In these cases, where there is employed a technique of directly applying coating sols to a support, such as by dip coating, doctor coating, bead coating, and the like, the overall coating speed is limited by the side of the support having the lower coating speed, the amount of coating, the drying capacity of the system, the properties of the various coating compositions, and the coating conditions. Hence it is difficult to apply precisely and with a high degree of speed coating compositions to the support having a high concentration and a high viscosity in thin layers.
Furthermore, where sol-like coating compositions are coated on opposite surfaces of a support in one step, there have been employed methods wherein both surfaces are coated with the coating compositions separately and methods wherein both surfaces are coated with them simultaneously. However, in the former method, since just after coating one surface of the support another surface thereof must be coated with a coating composition without contacting the coated layer to foreign materials such as solid walls, etc., it is difficult to obtain uniform thicknesses of coatings and good coating qualities.
Also, in methods of applying sol-like coating compositions simultaneously to the opposite surfaces of a support, at the same level, e.g., a method in which both surfaces of the support are coated simultaneously with coating compositions by doctor coating devices positioned at opposite sides of the support at the same level, the total thicknesses of the whole layers coated may be constant. However, it is difficult to obtain desired and uniform thicknesses of each layer on the surface of the support and good coating qualities.
Therefore, an object of the present invention is to provide a coating method for preparing photographic light sensitive elements in which both surfaces of a support are coated with coating compositions in one step while improving the coating efficiency and reducing the coating cost.
Another object of this invention is to provide a method in which dense coating compositions for photographic light sensitive elements can be applied precisely to oppo site surfaces of a support in thin layers in one step.
A further object of this invention is to provide a coating method capable of applying the aforesaid coating compositions to the opposite surfaces of a support simultaneously in multiple layers.
BRIEF DESCRIPTION OF INVENTION The invention comprises applying coating compositions for photographic light sensitive element to the fiat cooling surfaces of continuously moving members positioned at the opposite sides of a continuously travelling support to provide the cooling surfaces uniform layers having desired thicknesses and layer structures; gelling the layers thus applied; stripping the gelled thin layers from the cooling surfaces of the moving members, and closely adhering the layers thus stripped to the opposite surfaces of the contiguous continuously travelling support.
DETAILED DESCRIPTION OF DRAWING The invention will be explained, more in detail, by referring to the accompanying drawing, in which;
FIG. 1 is a schematic cross sectional view showing an embodiment of the invention and FIG. 2 is a schematic cross sectional view showing another embodiment of the invention.
In FIG. 1, a support 1 to be coated, such as a film base or a baryta-coated paper, continuously travels through a space defined by the two cooling drums 8 and 8 having cooling surfaces 3 and 3 respectively and continuously rotating in the directions of the arrows. Coating compositions for photographic light-sensitive elements are applied uniformly to the cooling surfaces 3 and 3' by means of coating devices 2 and 2 such as by extrusion hoppers or slide hoppers in thin layers having desired layer structures. The coating compositions thus applied to the cooling surfaces 3 and 3' are immediately cooled to form gelled thin layers 4 and 4. The thin layers 4 and 4' of the coating compositions thus gelled come into contact with the continuously travelling support 1 at the contact points 6 and 6 where the layers are closely adhered to the support. In this case, the support may travel with a speed identical to or faster than that of cooling surfaces 3 and 3'. In the case where the support travels faster than the speed of the cooling surfaces, the thin layers 4 and 4' are stretched at stretching points 5 and 5 to provide thinner layers 7 and 7. For example, if the speed of the support is 3 times as fast as the speed of the cooling surfaces, the thickness of the layers is reduced to about /3 of the thickness of the original layers. The cooling surfaces 3 and 3 of the cooling drums 8 and 8' are composed of such material that the thin layers 4 and 4 of the coating compositions are easily stripped therefrom. The cooling surfaces of the cooling drums are suitably maintained at a desired lower temperature by cooling from their interiors with av cooling medium for providing easily strippable cooled layers of the coating compositions. The temperatures of the cooling surfaces are determined by the kind of coating compositions, the coating temperature, the material comprising the cooling surfaces, etc. For instance, when a silver bromide emulsion is applied to a cooling surface plated wtih nickel at a temperature of 40 C., the gelled layer of the coating composition can be easily stripped from the cooling surface at a surface temperature of 1l0 C. For improving the adhesiveness between the support 1 and the layers 7 and 7' of the gelled coating compositions, the support 1 or the surfaces of the layers 4 and 4' of the gelled coating compositions to be adhered to the support may be preliminary heated by high frequency heating, infrared heating, or by blowing with hot air. Moreover, air pressure may be applied to the gelled and stretched layers at the stretching portions 5 and 5' to press the layers of the coating compositions to the travelling support, whereby the adhesive properties of the support 1 and the layers 7 and 7 of the coating compositions are improved.
In the case where the support 1 travels with a high rate of speed, there may be employed an apparatus capable of reducing the pressure of the atmosphere between the support 1 and the gelled layers of the coating compositions under stretching at the stretching portions 5 and 5' for preventing the entrance of air between the gelled layers 7 and 7 of the coating compositions and the support 1.
Moreover, it often happens that after stripping the gelled layers 4 and 4' of the coating compositions, water is condensed on the cooling surfaces 3 and 3' and accumulated in the spaces between the coating devices 2 and 2' and the cooling surfaces 3 and 3'. Hence the outlet ends of the coating device are cooled, and the coating compositions partially gelled to prevent the coating compositions from being supplied uniformly. For overcoming this difficulty, there may be provided an apparatus for removing the water directly before the coating compositions are applied to the cooling surfaces 3 and 3' by means of the coating devices.
FIG. 2 shows an embodiment of the invention in which the coating compositions applied to the cooling surfaces of cooling drums are transferred to a continuously travelling support separately. That is, a support 1 travels continuously while supported by a roller 9 and a roller 10. In this case, the back surface of the support is contacted to the roller surface 9 but the surface of the support having thereon a layer or layers of coating compositions is preventing from contacting the roller 10 by, e.g., air blow or air cushion.
DETAILED DESCRIPTION OF INVENTION Thus, by the method of this invention, whole layers of coating compositions for photographic light sensitive elements are applied to fiat and continuously moving cooling surfaces to provide thereon the gelled films of the coating compositions and the layers are stripped therefrom and adhered to the opposite surfaces of a continuously travelling support, whereby the coating efficiency is improved and the coating cost is reduced. Also, since the speed of the moving surfaces of the cooling members can be desirably varied in a range of 1% times the speed of the travelling support, dense and highly viscous coating compositions can be precisely applied in thin layers and with a high rate of speed to the opposite surface of a continuously travelling support without being limited by slower coating speeds drying capacity of the system and coating amounts.
Also, since in the method of this invention, the coating compositions are applied to a travelling surface after being gelled on the cooling surfaces of cooling members such as drums, the adverse elfects produced by the unevenness and the vibration of the continuously travelling support are lessened. The layer of the coating compositions are rapidly set, and the formation of uneven surfaces can be prevented which is not the case in the past where sol-like coating compositions were directly applied to the opposite surface of a support. Also, by the method of this invention, multiple layers of coating compositions having precise layer constructions can be simultaneously formed on opposite surfaces of a support when the gelled layers are transferred from the cooling surfaces to the support at a same level.
The invention will be further explained by the following example.
EXAMPLE By using the apparatus shown in FIG. 2, both surfaces of an under-coated film base were coated under the following conditions.
lst layer: silver bromide emulsion (70 cp. 2nd layer: silver bromide emulsion (50 cp.), and 3rd layer: aqueous gelatin solution (20 cp.).
The whole thickness of the aforesaid three layers was 300 microns on the cooling surface and microns after stretching.
Aqueous gelatin solution and dye (30 cps.)
The thickness of the above coating composition was 100 microns on the cooling surface and 100 microns after transferring to the support.
That is, the aforesaid three coating emulsions were applied in three layers to the cooling surface of the rotary drum having a diameter of 50 cm., and after setting by cooling, the layers thus formed were transferred to a film base travelling at a speed of 20 m./min. while stretching the layers to 3 times the thickness of the original layers. Thereafter, the coating composition for the back layer was applied to the cooling surface and after setting, the layer thus formed was transferred to the opposite surface of the film without stretching it, followed by drying immediately. By the procedure, a photographic light sensitive film having emulsion layers and a back layer having uniform thickness and good qualities was obtained.
What is claimed is:
1. A method for preparing a photographic light-sensitive element comprising applying a uniform layer or layers of predetermined thicknesses to each surface of a pair of continuously moving cooling members positioned at the opposite sides of a continuously travelling support, said layers comprising coating compositions where at least one of said layers is a photographic light sensitive composition gelling the thus formed layers by cooling, strip ping the gelled layers from the surfaces of said cooling members, and adhering the stripped layers to the opposite surfaces of said continuously travelling support.
2. The method according to claim 1 wherein said stripped, gelled layers are heated to an elevated temperature to promote adhesion to said support surfaces.
3. The method according to claim 1 wherein said layers gelled at the cooling surfaces are transferred to the continuously travelling support simultaneously.
6 4. The method according to claim 1 wherein said layers References Cited gelled at the cooling surfaces are transferred to the con- UNITED STATES N S tinuously travelling support at separate positions. 3 032 815 5/1962 Gerber 156 249X 5. The method according to claim 1 wherein said sup- 3362866 1/1968 Zahn port travels at substantially the same speed as that of 5 9/1968 igifjjil: 156 249X the surfaces of said cooling members.
6. The method according to claim 1 wherein said sup- BENJAMIN PADGETT, Primary Examiner port travels faster than the speed of the surfaces of said 3, J LECI-IERT, J A i t t Examiner cooling members to stretch the layers when they are trans- 0 U S Cl X R ferred from the cooling surfaces to the opposite surfaces of the support