« PreviousContinue »
(12) United States Patent
Aylward et al.
(io) Patent No.: US 6,274,284 Bl (45) Date of Patent: Aug. 14,2001
(54) NACREOUS IMAGING MATERIAL
(75) Inventors: Peter T. Aylward, Hilton; Alphonse D. Camp, Rochester; Robert P. Bourdelais, Pittsford, all of NY (US)
(73) Assignee: Eastman Kodak Company, Rochester, NY (US)
( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days.
(21) Appl. No.: 09/470,807
(22) Filed: Dec. 22, 1999
(51) Int. CI.7 G03C 1/79; G03C 1/93;
G03C 1/765; G03G 5/10
(52) U.S. CI 430/97; 430/201; 430/496;
430/523; 430/531; 430/533; 430/534; 430/536;
430/538; 347/105; 503/227
(58) Field of Search 430/534, 536,
430/538, 97, 201, 523, 531, 533, 496; 347/105;
(56) References Cited
U.S. PATENT DOCUMENTS 4,283,486 8/1981 Aono et al. .
4,632,869 12/1986 Park et al 428/315.5
4,758,462 7/1988 Park et al 428/213
5,141,685 8/1992 Maier et al 264/45.3
5,244,861 9/1993 Campbell et al 430/201
5,252,531 10/1993 Yasuda et al. .
5,275,854 1/1994 Maier et al 428/36.5
5,422,175 6/1995 Ito et al. .
5,434,039 7/1995 Nagata et al 430/538
5,443,951 8/1995 Yamamoto et al 435/6
5,466,519 11/1995 Shirakura et al 430/538
5,514,460 5/1996 Surman et al 428/304.4
5,866,282 2/1999 Bourdelais et al 430/536
5,888,643 3/1999 Aylward et al. .
5,888,681 3/1999 Gula et al 430/536
5,888,714 * 3/1999 Bourdelais et al 430/538
6,030,742 2/2000 Bourdelais et al 430/536
6,030,756 2/2000 Bourdelais et al 430/534
6,093,521 7/2000 Laney et al. .
FOREIGN PATENT DOCUMENTS WO 94/04961 3/1994 (WO) . * cited by examiner
Primary Examiner—Richard L. Schilling
(74) Attorney, Agent, or Firm—Paul A. Leipold
The invention relates to an imaging member comprising an image layer, a voided layer below said image layer, and below said voided layer a layer comprising white pigment wherein said imaging member is substantially free of white pigment above said voided layer, and said voided layer comprises a polymer matrix and voids containing gas.
21 Claims, 1 Drawing Sheet
NACREOUS IMAGING MATERIAL
FIELD OF THE INVENTION
This invention relates to imaging materials. In a preferred form, it relates to base materials for photographic reflective 5 paper.
BACKGROUND OF THE INVENTION
It has been proposed in U.S. Pat. No. 5,866,282 (Bourdelais et al.) to utilize a composite support material with laminated biaxially oriented polyolefin sheets as a photographic imaging material. In U.S. Pat. No. 5,866,282, biaxially oriented polyolefin sheets are extrusion laminated to cellulose paper to create a support for silver halide imaging layers. The biaxially oriented sheets described in U.S. Pat. No. 5,866,282 have a microvoided layer in combination with coextruded layers that contain white pigments such as Ti02 above and below the microvoided layer. The composite imaging support structure described in U.S. Pat. 2Q No. 5,866,282 has been found to be more durable, sharper and brighter than prior art photographic paper imaging supports that use cast melt extruded polyethylene layers coated on cellulose paper.
A photographic element with a microvoided sheet of 25 opalescence is described in U.S. Pat. No. 5,888,681 (Gula et al.). In U.S. Pat. No. 5,888,681 microvoided polymer sheets with microvoided polymer layer located between a cellulose paper base and developed silver halide imaging provide an image with a opalescence appearance. While the opales- 30 cence appearance is present in the image, the image suffers from a loss of image sharpness or acutance, a higher density minimum position and a decrease in printing speed compared to typical a photographic image on a white, reflecting base. It would be desirable if the desirable opalescent look 35 of the image could be maintained while improving printing speed, increasing sharpness and decreasing density minimum.
Prior art reflective photographic display materials with a polyester base use a Ti02 pigmented polyester base onto 40 which light sensitive silver halide emulsions are coated. It has been proposed in WO 94/04961 to use opaque polyester containing 10% to 25% Ti02 for a photographic support. The Ti02 in the polyester or paper base is always located directly under the image layer to provide optimum sharpness 45 and reflectivity. The Ti02 also gives the base support a slight yellow tint which is undesirable for a photographic material. Furthermore the Ti02 or other pigments corrupts the purity of the dye color. This is particularly true for reflective photographic images. For use as a photographic material, the 50 polyester or other substrate support containing Ti02 must be tinted blue to offset the yellow tint of the gelatin binder causing a loss in desirable whiteness and adding cost to the display material. Prior art photographic translucent display materials with incorporated diffusers which include trans- 55 mission and reflective display materials typically contain some level of white pigment to either diffuse the backlighting source in the case of transmission display materials or provide the desired reflective properties in the case of a reflective display material. go
In addition to the use of white pigments in reflective consumer photographs, white pigments are also utilized in photographic display materials for diffusion of illumination light source. While the use of white pigments in display materials does provide the desired diffusion and reflection 65 properties, the white pigments tend to change the hue angle of the color dyes in a developed photographic display image.
Dye hue angle is a measure in CIELAB color space of that aspect of color vision that can be related to regions of the color spectrum. For color photographic system there is a perceptual preferred dye hue angle for the yellow, magenta, and cyan dyes. It has been found that when photographic dyes are coated on support containing white pigments, the hue angle of the developed image changes compared to the hue angle of the dyes coated onto a transparent support. The hue angle change of photographic dyes caused by the presence of white pigments often reduces the quality level of the dyes compared to the dye set coated on a transparent base that is substantially free of white pigments. It would be desirable if a developed photographic dye set coated on a reflective support material had a dye hue angle that was not significantly different than the same dye set coated on a transparent support.
Prior art reflective photographic papers contain white pigments in the support just below the silver halide imaging layers to obtain image whiteness and sharpness during image exposure as the white pigment reduces the amount exposure light energy scattered by cellulose paper core. Details on the use of white pigments in highly loaded coextruded layers to obtain silver halide image sharpness and whiteness is recorded in U.S. Pat. No. 5,466,519.
PROBLEM TO BE SOLVED BY THE
There is a need for a reflective imaging material that provides less corruption of dye hue angle when coated on a translucent support while, at the same time, maintains photographic sharpness or printing speed and whiter in appearance to the viewer.
SUMMARY OF THE INVENTION
It is an object of the invention to provide improved imaging materials.
It is another object to provide photographic reflective materials that have a maintained dye hue angle.
It is a further object to provide improved image sharpness and printing speed compared to prior art voided base photographic materials.
It is an additional object to provide imaging materials that have a nacreous appearance.
These and other objects of the invention are accomplished by an imaging member comprising an image layer, a voided layer below said image layer, and below said voided layer a layer comprising white pigment wherein said imaging member is substantially free of white pigment above said voided layer, and said voided layer comprises a polymer matrix and voids containing gas.
ADVANTAGEOUS EFFECT OF THE
The invention provides brighter, snappy images by maintaining the dye hue of photographic dyes while, at the same time, providing images that have exceptional photographic sharpness and exposure speed. Further the images have a desirable nacreous appearance.
BRIEF DESCRIPTION OF THE DRAWINGS
The FIGURE is a drawing of the voided layer that provides the nacreous appearance.
DETAILED DESCRIPTION OF THE
The invention has numerous advantages over prior art photographic reflective materials. The reflective materials of
the invention provide an image with a nacreous appearance while maintaining efficient reflection of light, sharpness and photographic speed. Maintaining image sharpness and whiteness is important as consumers expect silver halide images to be high in quality. Further, maintaining printing 5 speed is critical for efficient photographic processing as a significant loss in printer speed could increase the cost of consumer silver halide images. The base materials also maintain the dye hue angle of developed photographic dyes similar to those coated on a transparent base and eliminate the undesirable interaction between white pigments such as Ti02 and imaging dyes. The optical properties of the imaging materials in accordance with the invention are improved as the tinting and optical brightening materials are concentrated in a layer of the biaxially oriented polymer sheet for most effective use with little waste of the colorant materials.
The nacreous imaging materials of the invention provide a eye catching appearance that make them particularly desirable in imaging applications that require obtaining the attention of the consumer. One example includes display 20 materials that are intended to communicate an advertising message to people in a public setting such as a bus top, train station or airport. The nacreous images are differentiated in look from prior art materials and thus provide the pop and sizzle that can catch consumers attention. By providing the 25 nacreous image with a pressure sensitive adhesive, the tough, durable nacreous image can be applied to various surfaces, which is particularly desirable for the youth market.
Photographic nacreous labels of the invention utilized in 30 packaging markets enable a differentiated look and consumer appeal on store shelf. The utilization of the thin, flexible, and tough silver halide materials results in a packaging material having many superior properties. The packaging materials of the invention have a depth of image 35 unsurpassed by existing packaging materials. The packaging materials of the invention may be utilized with a variety of packaging materials that are suitable pressure sensitive labeling, such as shampoo bottles, perfume bottles and film boxes. The packaging materials of the invention while 40 having the advantage of superior image are available on thin base materials which are low in cost while providing superior opacity and strength. The packaging materials of the invention as they may be imaged by flash optical exposure or digital printing have the ability to be formed in short runs 45 and to be rapidly switched from one image to the next without delay.
The photographic elements of this invention utilize an integral emulsion bonding layer that allows the emulsion to adhere to the support materials during manufacturing and 50 wet processing of images without the need for expensive subbing coatings. The nacreous appearance of the image can be created utilizing a variety of imaging techniques. In addition to silver halide images, ink jet images, thermal dye transfer images, and electrophotographic images all have the 55 nacreous appearance when the images are applied to the nacreous support. These and other advantages will be apparent from the detailed description below.
The terms as used herein, "top", "upper", "emulsion side", and "face" mean the side or toward the side of a 60 photographic member bearing the imaging layers. The terms "bottom", "lower side", and "back" mean the side or toward the side of the photographic member opposite from the side bearing the photosensitive imaging layers or developed image. The term substrate refers to any web base material 65 that the voided polymer sheet is applied. Nacreous appearance is a pearly, luster, iridescent, metallic sheen. A char
acteristic property of a nacreous appearance is an angular dependence of viewing angle.
For the imaging element of the invention, imaging layers are applied to the top-side of the nacreous base. The imaging element contains a voided polymer layer below the imaging layers. The layers above the voided layer and below the imaging layers are substantially free of white pigments that have been shown to corrupt the dye hue inks, pigments or dyes used to form an image. Polymer layers below the voided layer do contain white, reflecting pigments, which have been shown to significantly improve sharpness, whiteness and photographic printing speed compared to prior art materials. Surprisingly, it has been found that when the voided polymer sheets of the invention, when applied to a cellulose paper core, provide photographic image sharpness, and printing speed comparable to prior art coextruded support materials that contain white pigments just below the imaging layers.
Preferred white pigment in polymer layers below the voided layer comprises Ti02. Ti02 is preferred because of it has a high refractive index which is important in adding opacity to the imaging member as well as maintaining sharpness by reducing the amount of exposure light entering the highly scattering cellulose paper base. The white pigment-containing layer may have at least 0.10 grams/cc of Ti02. Below 0.10 g/cc there is a sufficiently low amount of Ti02 that the photographic sharpness and speed are not adequately improved. At levels above 1.5 g/cc potential problems may occur with interlayer adhesion and the ability to more a uniformity lump free layer. The imaging member of this invention may have a layer of white pigment selected from one of the group comprising of Ti02, BaS04, clay, talc, kaolin, and ZnS. The preferred spectral transmission of the white pigmented layer below the voided layer is less than 22%. Spectral transmission is the ratio of the transmitted power to the incident power and is expressed as a percentage as follows; TijGB=10~'D*100 where D is the average of the red, green and blue Status A transmission density response measured by an X-Rite model 310 (or comparable) photographic transmission densitometer.
The pre-formed voided polymer sheet preferably is an oriented polymer because of the strength and toughness developed in the orientation process. Preferred polymers for the flexible substrate include polyolefins, polyester and nylon. Preferred polyolefins include polypropylene, polyethylene, polymethylpentene, polystyrene, polybutylene, and mixtures thereof. Polyolefin copolymers, including copolymers of propylene and ethylene such as hexene, butene, and octene are also useful. Polyolefins are preferred, as they are low in cost and have the desirable strength and toughness properties required for a pressure sensitive label. Oriented polymer sheet have been shown to improve the tear resistance of the base material, reduce the curl of the image element and are generally capable of providing improved image sharpness and brightness compared to melt cast polymers. Examples of preferred biaxially oriented polymer sheet are disclosed in U.S. Pat. Nos. 5,866,282; 5,853,965; 5,874,205; 5,888,643; 5,888,683; 5,902,720; and 5,935,690. Further, the biaxially oriented sheets preferably laminated to cellulose paper, which are high in strength, have tear resistance greater than 150 N.
When white pigments are added to an oriented polymer layer the polymer layer preferably includes a stabilizing amount of hindered amine extruded on the top side of the imaging layer substrate. Hindered amine light stabilizers (HALS) originate from 2,2,6,6-tertramethylpiperidine. The hindered amine should be added to the polymer layer at