ARTICLE WITH OXIDATION PROTECTED layers in conjunction with vapor deposited overlayers
ADHESIVE AND ANTI-STATIC LAYER to provide anti-static properties to certain siliceous surfaces.
This invention relates to improving the adhesion of a Prior to this invention there has been no recognition hydrophilic colloid coating to a dielectric support while 5 in the art that metal-inorganic oxide layers are compatprotecting the resulting article from static electrical ible with the demanding requirements of photographic discharge. In one aspect, this invention relates to an ar- use and processing environments. Further, while vapor tide having a hydrophilic colloid coating and a dielec- deposited overlayers have been associated with metaltrie support which are bonded together by an inter- inorganic oxide layers, such overlayers differ markedly posed conductive adhesive layer having a surface resis- 10 in physical properties from hydrophilic colloids. Hytivity sufficiently low to allow the lateral conduction of drophilic colloid coatings are neither dimensionally staelectrical charge. In another aspect, this invention re- ble nor are they protective in aqueous solutions. For lates to a photographic article containing a radiation- example, hydrophilic colloids ingest water when sensitive material in which a hydrophilic colloid coat- brought into contact with aqueous solutions, such as ing is bonded to a dielectric support by an interposed 15 photographic processing solutions. The ingestion of adhesive and anti-static subbing layer. water creates substantial dimensional changes and/or Prior to this invention it has been recognized that in large internal stresses in the hydrophilic colloid, particphotographic structures incorporating a photosensitive ularly at a bonding surface. Typically, a hydrophilic emulsion coating on a dielectric support the accumula- colloid coating may ingest a quantity of water several tion of static charge on the support can have the unde- 20 times its original weight leading to doubling, tripling or sirable effect when accidentally discharge of fogging greater increase in its original thickness. When a hydrothe emulsion coating in the vicinity of the discharge. philic colloid is deposited directly on a support, such as Static charge accumulation is particularly troublesome a film support, it can be sloughed from the support on in roll films not containing gel pelloid layers or paper swelling of the layer during exposure to aqueous soluinterleavers, as is frequently the case in film applica- 25 tions. Accordingly, the art has heretofore generally utitions requiring minimal weight and/or rapid processing. lized subbing layers to facilitate adhesion of hydroOne approach that has been suggested in the art for philic colloid coatings to support surfaces. Since the dissipating or controlling static electrical charges on hydrophilic colloid coatings must inherently be permedielectric photographic supports involves the utiliza- able to aqueous solutions in order to allow phototion of a thin metal coating having sufficient conductiv- 30 graphic processing solutions to reach the radiationity to prevent high, localized static charge accumula- sensitive materials and addenda dispersed in the coition. The principal disadvantages associated with me- loid, the subbing layer is, of course, brought into direct tallic anti-static coatings are that when they are depos- contact with the processing solutions and must be resisited in thin films of less than about a 100 angstroms tant to attack thereby if the colloid is to remain bonded they become oxidixed during storage in association 35 to the support.
with the photographic emulsion coatings, so that their It is an object of this invention to provide an article conductances progressively decline and, hence, their having an adhesive anti-static subbing layer for bonding antistatic properties deteriorate. If the metal coatings a hydrophilic colloid coating to a dielectric support, are applied in sufficient thicknesses to offset their de- particularly a hydrophobic support, clining conductivities in the photographic environ- ^ It is still another object to provide a photographic arment, the increased thicknesses produce undesirable tide containing a radiation-sensitive material having a increases in optical density. In either instance the metal hydrophilic colloid coating bonded to a dielectric supanti-static coating can interact with the photosensitive port by an interposed subbing layer which is an antiemulsion coating to produce undesirable fogging. Fur- static layer and which is relatively inert and insoluble ther, the metal coating may inhibit bonding of a photo- in the course of photographic processing and also that graphic emulsion to the support, so that metal anti- is compatible with radiation-sensitive materials and adstatic coatings are typically placed on the support sur- denda.
face opposite to that of the photographic emulsion It is a further object to provide an article incorporat
coating. A further disadvantage is that when a support ing a subbing layer that is resistant to blocking,
having a freshly deposited metal anti-static layer These and other objects of the invention are accom
thereon is wound in reel form, the metal frequently will plished in one aspect by providing an article comprising
adhere to both adjacent surfaces. When this occurs the a dielectric support, a hydrophilic colloid coating and
metal may cause "blocking" — i.e., prevent unwinding a subbing layer which is contiguous to the support and
of the reel or, if unwinding is in fact accomplished, the 55 the hydrophilic colloid coating and is bonded to each,
metal coating may be partially and randomly trans- The subbing layer exhibits a surface resistivity of less
ferred to the opposite surface of the support. than 1012 ohms per square and is comprised of an elec
Prior to this invention it has been recognized that trical conductor capable of oxidation to a less conduc
vapor codeposited metal inorganic oxide layers are tive state and a protective inorganic oxide intimately
readily adherent to siliceous surfaces, such as glass, and 6Q intermixed with the electrical conductor in a concen
may be used to impart anti-static properties to glass tration sufficient to retard oxidation of the electrical
surfaces, such as windows, lenses, windshields and the conductor.
like. It has been recognized that these metal inorganic In accordance with this invention, it has been found
oxide layers may in turn receive vapor deposited over- that a hydrophilic colloid coating can be firmly bonded
layers, such as vapor deposited metal oxide, metal hal- ^ to a dielectric support surface by means of an adhesive
ide and metal overlayers. For example, Colbert et al. anti-static layer which is contiguous to the supporting
U.S. Pat. No. 2,808,351, issued Oct. 1, 1957, teaches surface and to the hydrophilic colloid. The adhesive an
using certain vapor codeposited metal-inorganic oxide ti-static layer is a binderless layer which consists essen3 4