Radiation imagery chemistry: process – composition – or product th – Thermographic process – Heat applied before imaging
Reexamination Certificate
1999-12-20
2001-02-20
Goodrow, John (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Thermographic process
Heat applied before imaging
C430S060000, C430S532000, C430S536000
Reexamination Certificate
active
06190842
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to supports for imaging elements, such as photographic, electrostatophotographic and thermal imaging elements, and in particular to supports comprising a polyester polymeric film, an adhesion promoting “subbing” layer, and imaging elements comprising the subbed polymeric film and an image forming layer. More particularly, this invention relates to subbed polymer supports and imaging elements wherein the subbing layer is present on the support during a heat treatment.
BACKGROUND OF THE INVENTION
Imaging elements generally comprise a support, adhesion or tie layers (subbing layers), image recording layers, and auxiliary layers that serve other functions, such as scratch resistance, static abatement, magnetic recording or lubrication. U.S. Pat. No. 6,037,108, titled “THERMALLY STABLE SUBBING LAYER FOR IMAGING ELEMENTS,” J. Chen, et al., filed Apr. 27, 1998, discusses the severe requirements for adhesion to the support and between layers in the imaging element. The inert character of most surfaces such as polyester surfaces presents considerable challenge for adhesion of layers coated thereon. As discussed in U.S. Pat. No. 6,037,108, J. Chen, et al., the adhesion difficulties have traditionally been overcome by the use of subbing systems involving etch agents as disclosed in U.S. Pat. No. 3,143,421, titled “ADHERING PHOTOGRAPHIC SUBBING LAYERS TO POLYESTER FILM,” by G. Nadeau, et al., Aug. 4, 1964; U.S. Pat. No. 3,201,249, titled “COMPOSITE FILM ELEMENT AND COMPOSITION THEREFOR INCLUDING ANTI-HALATION MATERIAL,” by G. Pierce, et al., Aug. 17, 1965, and U.S. Pat. No. 3,501,301, titled “COATING COMPOSITIONS FOR POLYESTER SHEETING AND POLYESTER SHEETING COATED THEREWITH,” by G. Nadeau, et al., Mar. 17, 1970, or alternatively, by energetic treatments, including corona discharge, glow discharge (see for example U.S. Pat. No. 5,425,980, titled “USE OF GLOW DISCHARGE TREATMENT TO PROMOTE ADHESION OF AQUEOUS COATS TO SUBSTRATE,” by J. Grace et al., Jun. 20, 1995, and references cited therein), ultraviolet radiation, electron beam, and flame treatment. Whether the support is treated by coating with a polymeric subbing layer containing an etchant or whether it is modified by energetic treatment, in many instances an additional subbing layer comprised of gelatin, or a single mixed subbing layer including a non-gelatin polymer and gelatin may be used. These gelatin and mixed subbing layers provide good adhesion to subsequently coated layers comprising hydrophilic colloid binders.
It is also mentioned in U.S. Pat. No. 6,037,108, that recently introduced systems such as the Advanced Photo System™ (APS) require thermal processing of the polyester support. The thermal processing is required in order to meet the mechanical specifications associated with the use of small format film in small cartridges, as well as the film loading and unloading mechanisms employed by APS cameras and APS film processors. The thermal treatment sufficiently reduces the core-set curling tendency of the polymeric film such that the mechanical requirements for the system are met. It is also stated that there are possible manufacturing benefits of coating the subbing layers prior to the requisite heat treatment. However, as disclosed in the above mentioned application, extended heat treatment or annealing processes applied to polyesters with gelatin or mixed subbing layers have been found to severely compromise the adhesion of subsequently coated hydrophilic colloid layers, such as silver halide emulsion layers of silver halide photographic elements.
The thermal degradation of the gelatin-containing subbing may result from thermally driven decomposition of the underlying support and subbing layer(s) and interaction of the byproducts with the gelatin subbing layer. In the case of a single mixed subbing layer, it may result from thermally driven chemical processes involving the non-gelatin polymer and gelatin. Hence, it may be desirable to have a single subbing layer that is both thermally stable and does not contain gelatin.
U.S. Pat. No. 5,563,029, titled “MOLECULAR GRAFTING TO ENERGETICALLY TREATED POLYESTERS TO PROMOTE ADHESION OF GELATIN-CONTAINING LAYERS,” by J. Grace et al., Apr. 3, 1995, discloses the use of amine reactive hardeners in combination with nitrogen glow-discharge treatment (or some other means of producing surface amines) applied to polyester support to provide the adhesion function of the subbing system. Grace et al. show that bis(vinylsulfonyl)methane, a representative amine reactive hardener, can be used as a molecular primer to bond a gelatin-containing layer to a plasma-treated support. It is taught that the amine reactive hardener chemically bonds to the plasma-treated support and that the gelatin then bonds to the amine reactive hardener. Similar to its function as a cross linking agent, the hardener links the gelatin to the treated surface by covalent bonds that are established by reaction of the vinylsulfone groups in the hardner with amine groups in the nitrogen-plasma-treated surface and in the gelatin coating. Grace et al. does not suggest that amine reactive hardeners in combination with appropriate surface treatment (e.g., glow discharge) provide a thermally stable subbing layer. In fact, one skilled in the art would likely expect that the highly reactive hardeners disclosed by Grace et al. would undergo undesirable chemical reactions under prolonged exposure to heat (e.g., as required for the manufacture of film base for Advanced Photo System™ film).
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a method for forming an imaging support element which includes a single subbing layer that is thermally stable and does not contain gelatin.
It is a further object of the present invention to provide a method for forming an imaging support element which includes a single subbing layer that retains its adhesion promoting characteristics under the heat treatment conditions required for manufacture of polyester film base, such as that used in the Advanced Photo System™ (APS).
It is an advantage of the present invention that the an imaging support element of the present invention which includes a nitrogen plasma treated polymeric film having an adhesion promoting layer formed thereon and is subjected to a heat treatment exhibits a reduction in the core-set curling tendency of the polymeric film.
Briefly stated, the foregoing and numerous other features, objects and advantages of the present invention will become readily apparent upon a reading of the detailed description, claims and figures set forth herein. These features, objects and advantages for producing an imaging support element are accomplished by forming a coating over a polymeric film support, the coating having a surface including amine reactive groups in a density of at least 10
10
per cm
2
and then heat treating the polymeric film support with the coating thereon at a temperature of from about the glass transition temperature (T
g
) of the polymeric film support minus 50° C. to about glass transition temperature (T
g
) of the polymeric film. The polymeric film support is nitrogen plasma treated. The layer comprises an amine reactive hardener or a chlorine-free non-gelatin polymer with amine reactive side groups. The layer may be formed by applying to the polymeric support web a coating including at least one non-amine reactive comonomer and a comonomer having amine reactive side groups. Alternatively, the layer may be formed by coating a monomer solution on the nitrogen plasma treated polymer support wherein the coated monomer has at least two vinyl sulfone groups which provide the amine reactive groups. The coating or subbing layer must not have chlorine-containing, thermally degradable constituents, either chemically bound or mixed in solution. Furthermore, if the coating or subbing layer is used in combination with an underlying chlorine-containing layer, the coating or subbing layer must be chemically stable in the presence of the dehy
Bowman Wayne A.
Burns Elizabeth G.
Castle Richard A.
Gerenser Louis J.
Grace Jeremy M.
Bocchetti Mark G.
Eastman Kodak Company
Goodrow John
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