Source: http://www.google.com/patents/US5466567?dq=KOI-18
Timestamp: 2014-10-22 23:16:39
Document Index: 533313954

Matched Legal Cases: ['in fine', 'in fine', 'in fine', 'in fine', 'in fine', 'in fine', 'in fine']

Patent US5466567 - Imaging element comprising an electrically-conductive layer containing ... - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsImaging elements, such as photographic, electrostatographic and thermal imaging elements, are comprised of a support, an image-forming layer and an electrically-conductive layer comprising a film-forming hydrophilic colloid having dispersed therein both electrically-conductive fine particles and pre-crosslinked...http://www.google.com/patents/US5466567?utm_source=gb-gplus-sharePatent US5466567 - Imaging element comprising an electrically-conductive layer containing conductive fine particles, a film-forming hydrophilic colloid and pre-crosslinked gelatin particlesAdvanced Patent SearchPublication numberUS5466567 APublication typeGrantApplication numberUS 08/330,409Publication dateNov 14, 1995Filing dateOct 28, 1994Priority dateOct 28, 1994Fee statusLapsedAlso published asEP0709729A2, EP0709729A3Publication number08330409, 330409, US 5466567 A, US 5466567A, US-A-5466567, US5466567 A, US5466567AInventorsCharles C. Anderson, Yongcai Wang, James L. Bello, Ibrahim M. Shalhoub, Douglas D. CorbinOriginal AssigneeEastman Kodak CompanyExport CitationBiBTeX, EndNote, RefManPatent Citations (8), Referenced by (26), Classifications (17), Legal Events (5) External Links: USPTO, USPTO Assignment, EspacenetImaging element comprising an electrically-conductive layer containing conductive fine particles, a film-forming hydrophilic colloid and pre-crosslinked gelatin particlesUS 5466567 AAbstract Imaging elements, such as photographic, electrostatographic and thermal imaging elements, are comprised of a support, an image-forming layer and an electrically-conductive layer comprising a film-forming hydrophilic colloid having dispersed therein both electrically-conductive fine particles and pre-crosslinked gelatin particles. The combination of hydrophilic colloid, electrically-conductive fine particles and pre-crosslinked gelatin particles provides a controlled degree of electrical conductivity and beneficial chemical, physical and optical properties which adapt the electrically-conductive layer for such purposes as providing protection against static or serving as an electrode which takes part in an image-forming process.
We claim: 1. An imaging element for use in an image-forming process; said imaging element comprising a support, an image-forming layer, and an electrically-conductive layer; said electrically-conductive layer comprising electrically-conductive fine particles, a film-forming hydrophilic colloid and pre-crosslinked gelatin particles.
2. An imaging element as claimed in claim 1, wherein said electrically-conductive fine particles are polymer particles.
3. An imaging element as claimed in claim 1, wherein said electrically-conductive fine particles are metal-containing particles.
4. An imaging element as claimed in claim 1, wherein said film-forming hydrophilic colloid is gelatin.
5. An imaging element as claimed in claim 1, wherein said electrically-conductive fine particles have an average particle size of less than 0.3 micrometers.
6. An imaging element as claimed in claim 1 wherein said electrically-conductive fine particles constitute 15 to 35 volume percent of said electrically-conductive layer.
7. An imaging element as claimed in claim 1, wherein said electrically-conductive fine particles exhibit a powder resistivity of 105 ohm-centimeters or less.
8. An imaging element as claimed in claim 1, wherein said pre-crosslinked gelatin particles have an average particle size of from about 10 to about 1000 nanometers.
9. An imaging element as claimed in claim 1, wherein said pre-crosslinked gelatin particles have an average particle size of from 20 to 500 nanometers.
10. An imaging element as claimed in claim 1, wherein said pre-crosslinked gelatin particles are present in said electrically-conductive layer in an amount of from 0.5 to 3 parts per part by weight of said film-forming hydrophilic colloid.
11. An imaging element as claimed in claim 1, wherein said electrically-conductive layer has a dry weight coverage of from about 100 to about 1500 mg/m2.
12. An imaging element for use in an image-forming process; said imaging element comprising a support, an image-forming layer, and an electrically-conductive layer; said electrically-conductive layer comprising a film-forming hydrophilic colloid having dispersed therein both electrically-conductive metal-containing particles and pre-crosslinked gelatin particles; said electrically-conductive metal-containing particles having an average particle size of less than 0.3 micrometers and constituting about 10 to about 50 volume percent of said electrically-conductive layer, and said pre-crosslinked gelatin particles having an average particle size of from about 10 to about 1000 nanometers and being present in said electrically-conductive layer in an amount of from about 0.3 to about 8 parts per part by weight of said film-forming hydrophilic colloid.
13. An imaging element as claimed in claim 12, wherein said electrically-conductive metal-containing particles are doped metal oxides.
14. An imaging element as claimed in claim 12, wherein said electrically-conductive metal-containing particles are metal oxides containing oxygen deficiencies.
15. An imaging element as claimed in claim 12, wherein said electrically-conductive metal-containing particles are metal nitrides, carbides or borides.
16. An imaging element as claimed in claim 12, wherein said electrically-conductive metal-containing particles are particles of antimony-doped tin oxide.
17. An imaging element as claimed in claim 12, wherein said electrically-conductive metal-containing particles are particles of aluminum-doped zinc oxide.
18. An imaging element as claimed in claim 12, wherein said electrically-conductive metal-containing particles are particles of niobium-doped titanium oxide.
19. An imaging element as claimed in claim 12, wherein said electrically-conductive metal-containing particles are colloidal particles of a metal antimonate.
20. A photographic film comprising:(1) a support; (2) an electrically-conductive layer which serves as an antistatic layer overlying said support; and (3) a silver halide emulsion layer overlying said electrically-conductive layer; said electrically-conductive layer comprising a film-forming hydrophilic colloid having dispersed therein both electrically-conductive metal-containing particles and pre-crosslinked gelatin particles; said electrically-conductive metal-containing particles having an average particle size of less than 0.3 micrometers and constituting about 10 to about 50 volume percent of said electrically-conductive layer, and said pre-crosslinked gelatin particles having an average particle size of from about 10 to about 1000 nanometers and being present in said electrically-conductive layer in an amount of from about 0.3 to about 8 parts per part by weight of said film-forming hydrophilic colloid. Description
FIELD OF THE INVENTION This invention relates in general to imaging elements, such as photographic, electrostatographic and thermal imaging elements, and in particular to imaging elements comprising a support, an image-forming layer and an electrically-conductive layer. More specifically, this invention relates to electrically-conductive layers containing conductive fine particles, a film-forming hydrophilic colloid and pre-crosslinked gelatin particles and to the use of such electrically-conductive layers in imaging elements for such purposes as providing protection against the generation of static electrical charges or serving as an electrode which takes part in an image-forming process.
Trevoy (U.S. Pat. No. 3,245,833) has taught the preparation of conductive coatings containing semiconductive silver or copper iodide dispersed as particles less than 0.1 μm in size in an insulating film-forming binder, exhibiting a surface resistance of 102 to 1011 ohms per square The conductivity of these coatings is substantially independent of the relative humidity. Also, the coatings are relatively clear and sufficiently transparent to permit their use as antistatic coatings for photographic film. However, if a coating containing copper or silver iodides was used as a subbing layer on the same side of the film base as the emulsion, Trevoy found (U.S. Pat. No. 3,428,451) that it was necessary to overcoat the conductive layer with a dielectric, water-impermeable barrier layer to prevent migration of semiconductive salt into the silver halide emulsion layer during processing. Without the barrier layer, the semiconductive salt could interact deleteriously with the silver halide layer to form fog and a loss of emulsion sensitivity. Also, without a barrier layer, the semiconductive salts are solubilized by processing solutions, resulting in a loss of antistatic function.
A highly effective antistatic layer incorporating an "amorphous" semiconductive metal oxide has been disclosed by Guestaux (U.S. Pat. No. 4,203,769). The antistatic layer is prepared by coating an aqueous solution containing a colloidal gel of vanadium pentoxide onto a film base. The colloidal vanadium pentoxide gel typically consists of entangled, high aspect ratio, flat ribbons 50-100 Å wide, about 10 Å thick, and 1,000-10,000 Å long. These ribbons stack flat in the direction perpendicular to the surface when the gel is coated onto the film base. This results in electrical conductivities for thin films of vanadium pentoxide gels (about 1 Ω-1 cm-1) which are typically about three orders of magnitude greater than is observed for similar thickness films containing crystalline vanadium pentoxide particles. In addition, low surface resistivities can be obtained with very low vanadium pentoxide coverages. This results in low optical absorption and scattering losses. Also, the thin films are highly adherent to appropriately prepared film bases. However, vandium pentoxide is soluble at high pH and must be overcoated with a non-permeable, hydrophobic barrier layer in order to survive processing. When used with a conductive subbing layer, the barrier layer must be coated with a hydrophilic layer to promote adhesion to emulsion layers above. (See Anderson et al, U.S. Pat. No. 5,006,451.)
Particularly preferred electrically-conductive layers which are especially advantagerous for use in imaging elements and are capable of effectively meeting the stringent optical requirements of silver halide photographic elements are layers comprising a dispersion in a film-forming binder of fine particles of an electronically-conductive metal antimonate as described in copending commonly assigned U.S. patent application Ser. No. 231,218, filed Apr. 22, 1994, "Imaging Element Comprising An Electrically-Conductive Layer Containing Particles Of A Metal Antimonate" by Paul A. Christian and Charles C. Anderson and issued Nov. 29, 1994, as U.S. Pat. No. 5,368,995. For use in imaging elements, the average particle size of the electrically-conductive metal antimonate is preferably less than about one micrometer and more preferably less than about 0.5 micrometers. For use in imaging elements where a high degree of transparency is important, it is preferred to use colloidal particles of an electronically-conductive metal antimonate, which typically have an average particle size in the range of 0.01 to 0.05 micrometers. The preferred metal antimonates have rutile or rutile-related crystallographic structures and are represented by either Formula (I) or Formula (II) below:
Electrically-conductive layers are also commonly used in imaging elements for purposes other than providing static protection. Thus, for example, in electrostatographic imaging it is well known to utilize imaging elements comprising a support, an electrically-conductive layer that serves as an electrode, and a photoconductive layer that serves as the image-forming layer. Electrically-conductive agents utilized as antisbatic agents in photographic silver halide imaging elements are often also useful in the electrode layer of electrostatographic imaging elements.
Anderson et al, U.S. Pat. No. 5,340,676, issued Aug. 23, 1994, describes conductive layers comprising electrically-conductive fine particles, a film-forming hydrophilic colloid, and water-insoluble polymer particles. Representative polymer particles described include polymers and interpolymers of styrene, styrene derivatives, alkyl acrylates or alkyl methacrylates and their derivatives, olefins, vinylidene chloride, acrylonitrile, acrylamide and methacrylamide derivatives, vinyl esters, vinyl ethers, or condensation polymers such as polyurethanes and polyesters. The use of a mixed binder comprising the water-insoluble polymer particles mentioned above in combination with a hydrophilic colloid such as gelatin provides a conductive layer that requires a lower volume percentage of conductive fine particles compared with a layer obtained from a coating composition comprising the conductive fine particles and hydrophilic colloid alone. As disclosed in the '676 patent, it is believed that the electrically-conductive layer described therein is able to provide improved conductivity at a reduced volume percentage of the electrically-conductive fine particles by virtue of the action of the water-insoluble polymer particles in promoting chaining of the electrically-conductive fine particles into a conductive network.
While U.S. Pat. No. 5,340,676 represents a major advance in the art of providing electrically-conductive layers suitable for use in imaging elements, the use of the water-insoluble polymer particles described therein can result in less than optimum adhesion when hydrophilic colloid layers such as photographic emulsion or curl control layers are applied over the electrically-conductive layer.
It is toward the objective of providing an improved electrically-conductive layer, which like that of U.S. Pat. No. 5,340,676 provides high conductivity at low volumetric percentages of electrically-conductive fine particles and which also provides excellent adhesive characteristics for overlying hydrophilic colloid layers, that the present invention is directed.
SUMMARY OF THE INVENTION In accordance with this invention, an imaging element for use in an image-forming process comprises a support, an image-forming layer, and an electrically-conductive layer; the electrically-conductive layer comprising electrically-conductive fine particles, a film-forming hydrophilic colloid and pre-crosslinked gelatin particles.
The gelatin particles used herein are pre-crosslinked gelatin particles, by which is meant that they are crosslinked before being introduced into the coating composition from which the electrically-conductive layer is formed. The pre-crosslinked gelatin particles utilized in this invention are pre-crosslinked to a degree at which they are substantially insoluble in an aqueous solution of a hydrophilic colloid. The word "particles" as used herein is intended to encompass any shape whatsoever as the particular shape of the particles is not critical.
In this invention, it is not feasible to crosslink the gelatin particles after the electrically-conductive layer has been coated since if particles of dried but non-crosslinked gelatin were incorporated in an aqueous hydrophilic colloid solution, they would tend to dissolve. It is, in fact, preferred that the pre-crosslinked gelatin particles utilized in this invention be particles of rather highly crosslinked gelatin so that very little swelling of these particles occurs.
In contrast with the mixed binder of U.S. Pat. No. 5,340,676 which is comprised of water-insoluble polymer particles such as polymethylmethacrylate particles and a film-forming hydrophilic colloid such as gelatin, the mixed binder of the present invention exhibits improved comparability since both the film-former and the particles are composed of a hydrophilic colloid. The combination of electrically-conductive fine particles, film-forming hydrophilic colloid and pre-crosslinked gelatin particles provides highly conductive coatings with low volume percentages of conductive fine particles and improved solution compatability compared with the coating compositions of U.S. Pat. No. 5,340,676. Thus, electrically-conductive layers of high transparency that are free of objectionable brittleness are readily obtained. Moreover, these layers strongly adhere to underlying and overlying layers such as photographic support materials and hydrophilic colloid layers.
The combination of electrically-conductive fine particles, film-forming hydrophilic colloid and pre-crosslinked gelatin particles provides a controlled degree of electrical conductivity and beneficial chemical, physical and optical properties which adapt the electrically-conductive layer for such purposes as providing protection against static or serving as an electrode which takes part in an image-forming process. Comparable properties cannot be achieved by using only the combination of electrically-conductive fine particles and film-forming hydrophilic colloid or the combination of electrically-conductive fine particles and pre-crosslinked gelatin particles. Thus, all three of the components specified are essential to achieving the desired results.
(f) electrically conducting salts such as described in U.S. Pat. No. 3,007,801 and 3,267,807.
Thermally processable imaging elements, including films and papers, for producing images by thermal processes are well known. These elements include thermographic elements in which an image is formed by imagewise heating the element. Such elements are described in, for example, Research Disclosure, Jun. 1978, Item No. 17029; U.S. Pat. No. 3,457,075; U.S. Pat. No. 3,933,508; and U.S. Pat. No. 3,080,254.
As described hereinabove, the imaging elements of this invention include an electrically-conductive layer comprising electrically-conductive fine particles, a film-forming hydrophilic colloid and pre-crosslinked gelatin particles.
The use of film-forming hydrophilic colloids in imaging elements is very well known. The most commonly used of these is gelatin and gelatin is a particularly preferred material for use in this invention as the film-forming hydrophilic colloid.
The electrically-conductive fine particles utilized in this invention can be of a wide variety of types as long as they are of suitable size and have a sufficient degree of electrical conductivity for the purposes of this invention. Preferably the electrically-conductive fine particles are metal-containing particles. However, conductive polymer particles can be used in place of metal-containing particles if desired. Examples of useful conductive polymer particles include crosslinked vinyl benzyl quaternary ammonium polymer particles as described in U.S. Pat. No. 4,070,189 and the conductive materials described in U.S. Pat. Nos. 4,237,174, 4,308,332 and 4,526,706 in which a cationically stabilized latex particle is associated with a polyaniline acid addition salt semiconductor.
In a particularly preferred embodiment of the present invention, the electrically-conductive fine particles are particles of an electronically-conductive metal antimonate as described in copending commonly assigned U.S. patent application Ser. No. 231,218 which is discussed hereinabove.
In the imaging elements of this invention, the electrically-conductive fine particles preferably have an average particle size of less than one micrometer, more preferably of less than 0.3 micrometers, and most preferably of less than 0.1 micrometers. It is also advantageous that the electrically-conductive fine particles exhibit a powder resistivity of 105 ohm-centimeters or less.
It is an important feature of this invention that it permits the achievement of high levels of electrical conductivity with the use of relatively low volumetric fractions of the electrically-conductive fine particles. Accordingly, in the imaging elements of this invention, the electrically-conductive fine particles preferably constitute about 10 to about 50 volume percent of the electrically-conductive layer. Use of significantly less than 10 volume percent of the electrically-conductive fine particles will not provide a useful degree of electrical conductivity. On the other hand, use of significantly more than 50 volume percent of the electrically-conductive fine particles defeats the objectives of the invention in that it results in reduced transparency due to scattering losses and in brittle layers which are subject to cracking and exhibit poor adherence to the support material. It is especially preferred to utilize the electrically-conductive fine particles in an amount of from 15 to 35 volume percent of the electrically-conductive layer.
The gelatin utilized to form the pre-crosslinked gelatin particles can be any of the types of gelatin described hereinabove. The gelatin can be crosslinked through the use of a conventional gelatin hardening agent as described in Research Disclosure, Number 365, Item 36544, September, 1994. Such hardeners include, for example, formaldehyde and free dialdehydes such as glutaraldehyde, blocked aldehydes such as 2,3-dihydroxy-1,4-dioxane, aziridines, triazines, vinyl sulfones, epoxides, and others. The gelatin fine particles can be prepared by a variety of methods. Gelatin crosslinked in aqueous solution can be dried to give a solid powder which can be milled to a fine particle in either aqueous or non-aqueous solvent using conventional particle size reduction methods, for example, media milling, sand milling, attrition milling or ball milling. Gelatin crosslinked in aqueous solution can be spray dried to a fine powder using conventional spray drying equipment and then redispersed in aqueous media in the presence of a surfactant. Alternatively, gelatin dissolved in aqueous solution can be emulsified in a non-water miscible solvent, crosslinked by addition of an appropriate hardener, and then dried to obtain the fine gelatin particles. These can then be redispersed into water in the presence of a surfactant.
To perform their function of promoting chaining of the electrically-conductive fine particles into a conductive network at low volume fractions it is essential that the pre-crosslinked gelatin particles be of very small size. Particularly useful pre-crosslinked gelatin particles are those having an average particle size of from about 10 to about 1000 nanometers, while preferred pre-crosslinked gelatin particles are those having an average particle size of from 20 to 500 nanometers.
In addition to the electrically-conductive fine particles, film-forming hydrophilic colloid and pre-crosslinked gelatin particles, the electrically-conductive layer can optionally contain wetting aids, lubricants, matte particles, biocides, dispersing aids, hardeners and antihalation dyes. The electrically-conductive layer is applied from an aqueous coating formulation that is preferably formulated to give a dry coating weight in the range of from about 100 to about 1500 mg/m2.
Incorporation in the electrically-conductive layer of pre-crosslinked gelatin particles of very small size, as described herein, is of particular benefit with electrically-conductive fine particles that are more or less spherical in shape. It is of less benefit with electrically-conductive fine particles that are fibrous in character, since fibrous particles are much more readily able to form a conductive network without the aid of the gelatin particles.
It is important that the pre-crosslinked gelatin particles be utilized in an effective amount in relation to the amount of hydrophilic colloid employed. Useful amounts are from about 0.3 to about 8 parts per part by weight of the film-forming hydrophilic colloid, while preferred amounts are from 0.5 to 5 parts per part by weight of the film-forming hydrophilic colloid, and particularly preferred amounts are from 0.5 to 3 parts per part by weight of the film-forming hydrophilic colloid. Use of too small an amount of the pre-crosslinked gelatin particles will prevent them from performing the desired function of promoting chaining of the electrically-conductive fine particles into a conductive network, while use of too large an amount of the pre-crosslinked gelatin particles will result in the formation of an electrically-conductive layer to which other layers of imaging elements may not adequately adhere.
In the electrically-conductive layer of this invention, the film-forming hydrophilic colloid forms the continuous phase and both the pre-crosslinked gelatin particles and the electrically-conductive fine particles are dispersed therein. As hereinabove described, all three of these ingredients are essential to achieving the desired result.
One of the most difficult problems to overcome in using electrically-conductive layers in imaging elements is the tendency of layers which are coated over the electrically-conductive layer to seriously reduce the electro-conductivity. Thus, for example, a layer consisting of conductive tin oxide particles dispersed in gelatin will exhibit a substantial loss of conductivity after it is overcoated with other layers such as a silver halide emulsion layer or anti-curl layer. This loss in conductivity can be overcome by utilizing increased volumetric concentrations of tin oxide but this leads to less transparent coatings and serious adhesion problems. In marked contrast, the electrically-conductive layers of this invention, which contain pre-crosslinked gelatin particles, retain a much higher proportion of their conductivity after being overcoated with other layers.
Particularly useful imaging elements within the scope of this invention are those in which the support is a transparent polymeric film, the image-forming layer is comprised of silver halide grains dispersed in gelatin, the film-forming hydrophilic colloid in the electrically-conductive layer is gelatin, the electrically-conductive fine particles are colloidal particles of a metal antimonate, the electrically-conductive layer has a surface resistivity of less than 1�1010 ohms/square and the electrically-conductive layer has a UV-density of less than 0,015.
An antistatic layer as described herein can be applied to a photographic film support in various configurations depending upon the requirements of the specific photographic application. In the case of photographic elements for graphics arts applications, an antistatic layer can be applied to a polyester film base during the support manufacturing process after orientation of the cast resin and coating thereof with a polymer undercoat layer. The antistatic layer can be applied as a subbing layer on the sensitized emulsion side of the support, on the side of the support opposite the emulsion or on both sides of the support. When the antistatic layer is applied as a subbing layer on the same side as the sensitized emulsion, it is not necessary to apply any intermediate layers such as barrier layers or adhesion promoting layers between it and the sensitized emulsion, although they can optionally be present. Alternatively, the antistatic layer can be applied as part of a multi-component curl control layer on the side of the support opposite to the sensitized emulsion during film sensitizing. The antistatic layer would typically be located closest to the support. An intermediate layer, containing primarily binder and antihalation dyes functions as an antihalation layer. The outermost layer typically contains binder, matte, and surfactants and functions as a protective overcoat layer. The outermost layer can, if desired, serve as the antistatic layer. Additional addenda, such as polymer latexes to improve dimensional stability, hardeners or cross linking agents, and various other conventional additives as well as conductive particles can be present in any or all of the layers.
In the case of photographic elements for direct or indirect x-ray applications, the antistatic layer can be applied as a subbing layer on either side or both sides of the film support. In one type of photographic element, the antistatic subbing layer is applied to only one side of the support and the sensitized emulsion coated on both sides of the film support. Another type of photographic element contains a sensitized emulsion on only one side of the support and a pelloid containing gelatin on the opposite side of the support. An antistatic layer can be applied under the sensitized emulsion or, preferably, the pelloid. Additional optional layers can be present. In another photographic element for x-ray applications, an antistatic subbing layer can be applied either under or over a gelatin subbing layer containing an antihalation dye or pigment. Alternatively, both antihalation and antistatic functions can be combined in a single layer containing conductive particles, antihalation dye, the film-forming hydrophilic colloid and the pre-crosslinked gelatin particles. This hybrid layer can be coated on one side of a film support under the sensitized emulsion.
Preparation of pre-crosslinked gelatin fine particles
85.2 g of lime-processed bone gelatin were added to 450 g of distilled water. The gel was allowed to swell for one hour and the mixture was heated at 45� C. 208 g of 1.8 wt % bis(vinyl methyl)sulfone solution in water and 7.5 g of 50 wt % trifunctional aziridine solution in ethanol were added and the solution stirred for several minutes. The mixture was refrigerated overnight to set the gelatin solution. The gelatinous solid was then sliced into small cubes and dried in an air oven at 35� C. until it was visually dry (about 6 hours). The dry gel was then kept at 21� C. and 80% RH for 24 hours and then heated at 105� C. for an additional 24 hours. The dried, crosslinked gelatin was broken into small pieces, dry ground to a particle size of about 50 μm, and then media milled in an aqueous slurry to an average particle size less than about 0.5 μ m. The slurry of pre-crosslinked gelatin fine particles was used in the following examples.
Examples 1-5 and Comparative Examples A-H Antistat coatings comprising electrically-conductive fine particles and gelatin binder were coated onto 4 mil thick polyethylene terephthalate film support that had been subbed with a terpolymer latex of acrylonitrile, vinylidene chloride, and acrylic acid. The aqueous coating formulations comprising about 2 weight % total solids were dried at 120� C. to give dried coating weights of 500 mg/m2. The coating formulations contained 0.5 to 1.5 weight % of conductive tin oxide particles (doped with 6% antimony) with an average particle size of about 50 nm, 0.5 to 1.5 weight % of a gelatin binder comprising a mixture of pre-crosslinked gelatin fine particles and water-soluble gelatin, 0.02 weight % of 2,3-dihydroxy-1,4-dioxane gelatin hardener, and 0.01 weight % of a nonionic wetting aid (Olin 10G made by Olin Chemical Co.).
The surface resistivity of the coatings was measured at 20% relative humidity using a 2-point probe. The coating compositions and resistivities for the coatings are tabulated in Table 1. For purposes of comparison, results are also reported for Comparative Examples A to H in which either the tin oxide particles, the pre-crosslinked gelatin fine particles, or both were omitted or water-insoluble polymer particles described in U.S. Pat. No. 5,340,676 were used in place of the pre-crosslinked gelatin fine particles.
As shown by the data in Table 1, coatings of this invention provide excellent conductivity at much lower volume percent of the electrically-conductive particle than those comprising only water-soluble gelatin as the binder. For coatings comprising 15 volume % electrically-conductive particles, compositions of the present invention had resistivities three orders of magnitude superior compared with those containing only water-soluble gelatin as the binder and were also superior to those containing the water-insoluble polymer particles of U.S. Pat. No. 5,340,676.
TABLE 1______________________________________                              Surface                    Volume %  ResisitivityExample No.    Binder          SnO2 (&#937;/square)______________________________________1        2/1 pre-crosslinked                    15        3.1 � 109    gelatin    particles/soluble gelatin2        2/1 pre-crosslinked                    35        3.1 � 107    gelatin    particles/soluble gelatin3        3/2 pre-crosslinked                     5        1.0 � 1014    gelatin    particles/soluble gelatin4        3/2 pre-crosslinked                    15        6.3 � 109    gelatin    particles/soluble gelatin5        3/2 pre-crosslinked                    35        5.0 � 107    gelatin    particles/soluble gelatinA        Water soluble    5        1.0 � 1014    gelatin onlyB        Water soluble   15        8.0 � 1012    gelatin onlyC        Water soluble   35        2.0 � 109    gelatin onlyD        Water soluble    0        1.0 � 1014    gelatin onlyE        2/1 pre-crosslinked                     0        1.0 � 1014    gelatin    particles/soluble gelatinF        3/2 polymer latex*/                     5        1.0 � 1014    water soluble    gelatinG        3/2 polymer latex*/                    15        1.0 � 1011    water soluble    gelatinH        3/2 polymer latex*/                    35        2.0 � 108    water soluble    gelatin______________________________________ *-styrene/n-butyl methacrylate/2sulfoethyl methacrylate sodium salt (30/60/10) latex
Examples 6-7 and Comparative Example I-J Conductive coatings were prepared in the aforementioned manner and these were then overcoated with a gelatin coating containing bis(vinyl methyl)sulfone hardener in order to simulate overcoating with a photographic emulsion or curl control layer. This gelatin layer was chill set at 15� C. and dried at 40� C. to give a dried coating weight of 4500 mg/m2.
The internal resistivity of the overcoated samples was measured at 20% relative humidity using the salt bridge method described in R. A. Elder, "Resistivity Measurements on Buried Conductive Layers", EOS/ESD Symposium Proceedings, September 1990, pp. 251-254. Dry adhesion of the gelatin overcoat to the conductive layer was determined by scribing small hatch marks in the coating with a razor blade, placing a piece of high tack tape over the scribed area and then quickly pulling the tape from the surface. The amount of the scribed area removed is a measure of the dry adhesion. Wet adhesion for the samples was tested by placing the test samples in developing and fixing solutions at 35� C. each and then rinsing in distilled water. While still wet, a one millimeter wide line was scribed in the gelatin overcoat layer and a finger was rubbed vigorously across the scribe line. The width of the line after rubbing was compared to that before rubbing to give a measure of wet adhesion. The description of the samples and the results obtained are reported in Table 2.
As indicated in Table 2 use of pre-crosslinked gelatin fine particles in combination with water-soluble gelatin gave excellent electro-conductive properties before and after a gelatin overcoat was applied. It also gave excellent wet and dry adhesion to the overcoat layer. Comparative Example I in which only water-soluble gelatin was used in the coating formulation as the binder for the electrically-conductive particle gave unacceptable electro-conductive properties after overcoating. In Comparative Example I, a gelatin hardener, 2,3-dihydroxy-1,4-dioxane, was added to the coating formulation to crosslink the gelatin binder as the coating dried. However, using a binder that comprises only water-soluble gelatin that is crosslinked during the drying process does not provide the advantageous electro-conductive properties of the invention. In addition, the coatings of the present invention provide further improvements with respect to both electro-conductive properties after overcoating and wet adhesion to an overlying layer compared to the compositions described in U.S. Pat. No. 5,340,676 as can be seen by comparison of Example 7 of the present invention and Comparative Example J.
TABLE 2__________________________________________________________________________                 Resistivity                       Resistivity                 Before                       AfterExampleConductive Layer Binder             Vol %                 Overcoat                       Overcoat                             Wet  DryNo.  Composition  SnO2                 &#937;/square                       &#937;/square                             Adhesion                                  Adhesion__________________________________________________________________________6    2/1 pre-crosslinked             35  3.1 � 107                       3.1 � 108                             Excellent                                  Excellentgelatin/soluble gelatin7    3/2 pre-crosslinked             35  5.0 � 107                       5.0 � 107                             Excellent                                  Excellentgelatin/soluble gelatinI    Water soluble gelatin             35  2.0 � 109                       1.0 � 1014                             Excellent                                  ExcellentonlyJ    3/2 polymer latex*/             35  2.0 � 108                       1.2 � 109                             Good Excellentwater soluble gelatin__________________________________________________________________________ *styrene/n-butyl methacrylate/2sulfoethyl methacrylate sodium salt (30/60/10) latex
The imaging elements of this invention exhibit many advantages in comparison with similar imaging elements known heretofore. For example, because they are able to utilize relatively low concentrations of the electrically-conductive fine particles they have excellent transparency characteristics and they are free from the problems of excessive brittleness and poor adhesion that have plagued similar imaging elements in the prior art. Their adhesion properties are particularly excellent because both components of the binder system are hydrophilic colloids and thus are compatible with the hydrophilic colloids commonly used in other layers of imaging elements. Also, because they are able to employ electrically-conductive fine particles of very small size they avoid the problems caused by the use of fibrous particles of greater size, such as increased light scattering and the formation of hazy coatings. It has been proposed heretofore to incorporate non-conductive auxiliary fine particles such as oxides, sulfates or carbonates in electrically-conductive layers comprised of metal-containing particles dispersed in a binder (see for example, U.S. Pat. No. 4,495,276). However, the use of auxiliary fine particles of high refractive index in an effort to reduce the amount of electrically-conductive metal-containing particle employed is not beneficial since it will result in the formation of a hazy, high minimum density coating. Moreover, the layer will be brittle and subject to cracking. It has also been proposed heretofore to utilize the combination of a binder, such as a hydrophilic colloid, an electrically-conductive metal oxide particle, such as doped tin oxide, and an electro-conductive polymer such as poly(sodium styrene sulfonate) or other polyelectrolyte (see for example, U.S. Pat. Nos. 4,275,103 and 5,122,445). However, water-soluble polymers, such as polyelectrolytes, do not significantly reduce the volume fraction of electrically-conductive metal-containing particles needed for good conductivity. This is especially the case at low humidity where polyelectrolytes contribute little to conductivity. Combining a water-soluble polymer such as polyacrylamide, hydroxyethyl cellulose, polyvinyl pyrrolidine or polyvinyl alcohol with gelatin yields results that are no different than using gelatin alone. Thus, it is a key feature of the present invention to utilize pre-crosslinked gelatin particles in an amount effective to permit the use of low volumetric concentrations of the electrically-conductive fine particles.
Similar results to those described in the above examples can be obtained by using hydrophilic colloids other than gelatin, by using pre-crosslinked gelatin particles other than those specifically described, and by using electrically-conductive fine particles other than antimony-doped tin oxide.
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS4275103 *Jul 5, 1979Jun 23, 1981Matsushita Electric Industrial Co., Ltd.Polymeric electrolyte binder for tin oxide, indium oxide or zinc oxideUS4495276 *Apr 13, 1981Jan 22, 1985Fuji Photo Film Co., Ltd.Silver halide element with electroconductive metal oxide layerUS5066572 *Mar 22, 1990Nov 19, 1991Eastman Kodak CompanyControl of pressure-fog with gelatin-grafted and case-hardened gelatin-grafted soft polymer latex particlesUS5122445 *Jun 19, 1990Jun 16, 1992Fuji Photo Film Co., Ltd.Silver halide photographic materialsUS5248558 *Jun 20, 1991Sep 28, 1993Eastman Kodak CompanyCase-hardened gelatin-grafted polymer particlesUS5340676 *Mar 18, 1993Aug 23, 1994Eastman Kodak CompanyImaging element comprising an electrically-conductive layer containing water-insoluble polymer particlesUS5368995 *Apr 22, 1994Nov 29, 1994Eastman Kodak CompanyImaging element comprising an electrically-conductive layer containing particles of a metal antimonateUS5374498 *May 13, 1993Dec 20, 1994Konica CorporationContaining a hydrazine derivative and latex* Cited by examinerReferenced byCiting PatentFiling datePublication dateApplicantTitleUS5518867 *Feb 27, 1995May 21, 1996Eastman Kodak CompanyElectron beam recording process utilizing an electron beam recording film with low visual and ultraviolet densityUS5534397 *May 18, 1995Jul 9, 1996Eastman Kodak CompanyElectron beam recording film with low visual and ultraviolet densityUS5667950 *Nov 13, 1996Sep 16, 1997Eastman Kodak CompanyHigh-contrast photographic elements protected against halationUS5698384 *Dec 5, 1995Dec 16, 1997Eastman Kodak CompanyImaging element comprising an electrically-conductive layer with enhanced abrasion resistanceUS5849472 *Mar 13, 1997Dec 15, 1998Eastman Kodak CompanyImaging element comprising an improved electrically-conductive layerUS5905021 *Feb 12, 1996May 18, 1999Eastman Kodak CompanyImaging element comprising an electrically-conductive layer containing conductive fine particles and water-insoluble polymer particles containing sulfonic acid groupsUS5912109 *Feb 12, 1996Jun 15, 1999Eastman Kodak CompanyPhotographic film; antimony doped tin oxideUS6001549 *May 27, 1998Dec 14, 1999Eastman Kodak CompanyElectrically conductive layer comprising microgel particlesUS6025119 *Dec 18, 1998Feb 15, 2000Eastman Kodak CompanyImaging element including support, image-forming layer, electrically conductive layer comprising layered siliceous material, electrically conductive polymer that can intercalate with or exfoliate said siliceous material, film-forming binderUS6060230 *Dec 18, 1998May 9, 2000Eastman Kodak CompanyImaging element comprising an electrically-conductive layer containing metal-containing particles and clay particles and a transparent magnetic recording layerUS6066442 *Oct 21, 1996May 23, 2000Konica CorporationPlastic film having an improved anti-static propertyUS6077655 *Mar 25, 1999Jun 20, 2000Eastman Kodak CompanyContaining polypyrrole, polythiophene, polyaniline or graft polymers of gelatin and a vinyl polymerUS6096491 *Oct 15, 1998Aug 1, 2000Eastman Kodak CompanyAntistatic layer for imaging elementUS6114079 *Apr 1, 1998Sep 5, 2000Eastman Kodak CompanyElectrically-conductive layer for imaging element containing composite metal-containing particlesUS6117628 *Feb 27, 1998Sep 12, 2000Eastman Kodak CompanyAn imaging element of a support, an image-forming layer and a transparent, electroconductive, abrasion-resistaint, anti-static, protective backing of metal particles dispersed in crosslinked polyurethane; photography; thermographyUS6124083 *Oct 15, 1998Sep 26, 2000Eastman Kodak CompanyAn electrically-conductive layer comprising a sulfonated polyurethane film-forming binder and an electroconductive polymer comprising substituted or unsubstituted polypyrroles, polythiophenes and polyanilinesUS6187522Mar 25, 1999Feb 13, 2001Eastman Kodak CompanyScratch resistant layer comprising a polymer having a modulus greater than 100 mpa measured at 20 degree c. and a tensile elongation to break greater than 50%US6190846Oct 15, 1998Feb 20, 2001Eastman Kodak CompanyAbrasion resistant antistatic with electrically conducting polymer for imaging elementUS6355406Dec 12, 2000Mar 12, 2002Eastman Kodak CompanyAdjustment of ph of aqueous solution; electroconductivity polymerUS6465140May 11, 2001Oct 15, 2002Eastman Kodak CompanyMethod of adjusting conductivity after processing of photographsUS6479228Dec 1, 2000Nov 12, 2002Eastman Kodak CompanyScratch resistant layer containing electronically conductive polymer for imaging elementsUS7267988Mar 21, 2003Sep 11, 2007Carestream Health, Inc.Dosimeter with conducting layerUS7846547 *Jun 9, 2004Dec 7, 2010Sony Corporationacrylic acid-styrene copolymers; surface treated with trimethylolpropane-tri- beta -aziridinylpropionate; solvent-resistance, conduction reliability; for use in anisotropic conductive adhesiveUS8092904 *Mar 31, 2006Jan 10, 20123M Innovative Properties CompanyOptical article having an antistatic layerEP0789268A1Jan 29, 1997Aug 13, 1997Eastman Kodak CompanyImaging element comprising an electrically-conductive layerEP0864920A1 *Mar 3, 1998Sep 16, 1998Eastman Kodak CompanyImaging element comprising an electrically-conductive layer* Cited by examinerClassifications U.S. Classification430/530, 430/537, 430/527, 430/63, 430/640, 430/271.1, 430/539International ClassificationG03G5/10, G03G5/14, B41M5/28, G03C1/85, B41M5/40, B41M5/30Cooperative ClassificationG03G5/10, G03C1/85European ClassificationG03C1/85, G03G5/10Legal EventsDateCodeEventDescriptionJan 13, 2004FPExpired due to failure to pay maintenance feeEffective date: 20031114Nov 14, 2003LAPSLapse for failure to pay maintenance feesJun 4, 2003REMIMaintenance fee reminder mailedMay 3, 1999FPAYFee paymentYear of fee payment: 4Oct 28, 1994ASAssignmentOwner name: EASTMAN KODAK COMPANY, NEW YORKFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:ANDERSON, CHARLES C.;WANG, YONGCAI;BELLO, JAMES L.;AND OTHERS;REEL/FRAME:007210/0938;SIGNING DATES FROM 19941027 TO 19941028RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services©2012 Google