Polyethyleneimine primer for imaging materials

Details Polyethyleneimine primer for imaging materials Polyethyleneimine primer for imaging materials

2001-10-29

2003-02-04

Schilling, Richard L. (Department: 1752)

Radiation imagery chemistry: process, composition, or product th

Transfer procedure between image and image layer, image...

Imagewise heating, element or image receiving layers...

C430S531000, C430S532000, C430S533000, C430S536000, C430S537000, C347S105000

Reexamination Certificate

active

06514660

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to primer layers and methods of forming them on imaging members, particularly those comprising gelatin.
BACKGROUND OF THE INVENTION
The use of polymeric base in imaging members is well known. Typically, the base of the imaging member comprises a hydrophobic polymer, and the image receiving layer comprises hydrophilic colloids, such as gelatin.
Hydrophilic colloids such as gelatin have many unique and desirable properties that make them especially useful in the preparation of photographic materials. For example, gelatin has high swellability in aqueous media which allows rapid diffusion of compounds in and out of a gelatin-containing photographic layer during film processing. Gelatin is also an excellent dispersing medium for light-sensitive silver halide grains and aqueous gelatin solutions exhibit excellent coating properties and quickly undergo gelation when chilled; all of these properties are critical to the manufacture of photographic films. In case of inkjet applications, the ability of gelatin containing layers to absorb water and water-based inks has promoted their use in inkjet image receiving media. In addition, crosslinked gelatin layers provide very good physical properties such as resistance to scratch, abrasion, ferrotyping, and blocking.
However, adhesion of gelatin containing layers on to a hydrophobic polymeric substrate has been known to be problematic. In case of photographic products such as films, where oriented polyester based substrates such as polyethylene terephthalate and polyethylene naphthalate are used, adhering gelatin base photographic emulsion to the substrate has been difficult. This problem is exacerbated by the conditions to which photographic elements are subjected; i.e., the adhesion must not fail in the raw and processed dry state, as well as when the film is wet during the development process.
Several adhesion promoting “subbing” materials, such as poly(methyl acrylate-co-vinylidene chloride-co-itaconic acid) and poly(acrylonitrile-co-vinylidene chloride-co-acrylic acid) disclosed in U.S. Pat. Nos. 3,201,249 and 3,143,421, respectively, provide the required adhesion when applied before orientation but are not as effective when applied on oriented polyester support. The effectiveness of these adhesive materials may be enhanced by the use of swelling or attack agents such as resorcinol.
An alternative approach disclosed in U.S. Pat. No. 4,695,532 describes a discharged treated polyester film support having coated directly thereon a crosslinked layer of an aqueous vinyl acrylate copolymer and gelatin mixture. Although this system has good adhesion before processing, the adhesion performance is severely degraded by photographic developing solutions.
U.S. Pat. No. 5,639,589 discloses a polyester film support having a surface bearing an improved subbing layer which comprises a mixture of gelatin and a vinyl polymer in which the ratio of gelatin to polymer and the dry coverage of the layer are specified.
EP 0583787 A2 discloses the use of glow discharge treatment to enhance the adhesion of photographic elements. This treatment involves the use of high energy plasma under vacuum which requires specific equipment.
U.S. Pat. No. 5,378,592 discloses the use of a two-layer subbing layer (for photographic materials) wherein the first subbing layer is a layer of polyurethane latex cured with an epoxy compound or a dichloro-s-triazine derivative, and the second subbing layer is a hydrophilic colloid layer comprising gelatin.
U.S. Pat. No. 5,532,118 describes the use of a layer of a self-crosslinking polyurethane as an adhesion promoting material for polyester film support. U.S. Pat. No. 5,910,401 describes a similar use of a gelatin-grafted polyurethane for adhesion promotion.
In case of reflective photographic elements such as resin coated or laminated photographic paper, a similar problem of emulsion adhesion to the hydrophobic resin exists. In case of conventional polyethylene coated paper, emulsion adhesion is achieved by means of surface modification of the polyethylene surface through corona discharge treatment. Although the process may provide adequate adhesion, corona discharge treatment, if not carefully controlled, can give rise to surface defects such as mottle upon emulsion coating. Additionally, owing to the deleterious aging of the corona treated surface it is preferred that corona discharge treatment is administered to the support, in-line with emulsion coating or at least within a short period, preferably less than 48 hours and more preferably less than 24 hours, before emulsion coating. This poses limitations on manufacturing site (since some emulsion coating facilities may not be equipped with in-line corona discharge treatment capability) or flow through the emulsion coating operation.
More recent photographic elements such as those disclosed in U.S. Pat. Nos. 5,853,965; 5,866,282; 5,874,205; 5,888,681; 5,935,690; 5,955,239; 5,968,722; 6,001,547; 6,017,685; 6,017,686; 6,030,756; 6,045,965; 6,048,606; 6,063,552; 6,074,788; etc., utilize polypropylene, specifically oriented polypropylene, in the support, to leverage various advantages. However, photographic emulsion cannot be adhered to these polypropylene surfaces even with in-line corona discharge treatment. In these cases, a polyethylene skin layer is co-extruded on the polypropylene core, which is corona discharge treatable for emulsion adherence. Although the polyethylene skin layers afford emulsion adhesion, these extra layers add to the complexity of the manufacturing set up and process for the supports.
Use of polyethyleneimine based primer layers on polypropylene substrates is known in the art. For example, U.S. Pat. No. 4,663,216 discloses a polyethyleneimine-primed synthetic paper substrate for allegedly improved ink absorption. U.S. Pat. No. 5,248,364 and 5,510,180 disclose multi layer laminates containing a layer of a polypropylene material permanently bonded to a polyethyleneimine-primed substrate for packaging. U.S. Pat. No. 5,486,426 discloses use of a polyethyleneimine primer in a cold sealable polyolefin substrate. U.S. Pat. No. 5,776,604 discloses a lithographic printable polypropylene substrate, which is primed with polyethyleneimine. U.S. Pat. Nos. 5,827,615 and 6,013,353 disclose metallized multilayer polypropylene packaging films primed with polyethyleneimine. U.S. Pat. No. 6,232,056 discloses imaging elements with polyethyleneimine fuser layer for backside splice enhancement, particularly heat splicing in high speed photographic printers such as the Agfa MSP printer. However, none of the prior art teaches of a primer layer comprising polyethyleneimine and gelatin for adhering image receiving layers such as photographic emulsions on to imaging supports.
There is a critical need to develop primer layers, which can be easily incorporated on imaging members, particularly those with highly hydrophobic supports such as oriented polypropylenes and polyesters, in order to attain adhesion of image receiving layers, such as those comprising photographic emulsions, on to said supports.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a novel imaging member with superior adhesion of its image receiving layer.
It is an object of the invention to provide a primer layer that can be easily incorporated on a hydrophobic polymeric sheet, which constitutes the base for an imaging member.
It is another object of the invention to superimpose an image receiving layer on the said primer, without any further surface treatment of the said primer layer
These and other objects of the invention are achieved by providing an imaging member comprising a polymer sheet, a primer layer comprising polyethyleneimine and gelatin contacting said polymer sheet, and an image receiving layer contacting said primer layer.
DETAILED DESCRIPTION OF THE INVENTION
The present invention has numerous advantages. The invention provides excellent adhesion of the image receiving layer to the imaging support, which comprises a hydrophobic polymeric s

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