Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2001-12-28
2004-06-01
Meier, Stephen (Department: 2853)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S095000, C106S031130, C106S031600
Reexamination Certificate
active
06742885
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to inks and a porous ink jet recording element for ink jet printing that provides images with improved gloss difference in imaged and non-imaged areas
BACKGROUND OF THE INVENTION
In a typical ink jet recording or printing system, ink droplets are ejected from a nozzle at high speed towards a recording element or medium to produce an image on the medium. The ink droplets, or recording liquid, generally comprise a recording agent, such as a dye or pigment, and a large amount of solvent. The solvent, or carrier liquid, typically is made up of water and an organic material such as a monohydric alcohol, a polyhydric alcohol or mixtures thereof.
An inkjet recording element typically comprises a support having on at least one surface thereof an ink-receiving or image-receiving layer, and includes those intended for reflection viewing, which have an opaque support, and those intended for viewing by transmitted light, which have a transparent support.
An important characteristic of ink jet recording elements is their need to dry quickly after printing. To this end, porous recording elements have been developed which provide nearly instantaneous drying as long as they have sufficient thickness and pore volume to effectively contain the liquid ink. For example, a porous recording element can be manufactured by cast coating, in which a particulate-containing coating is applied to a support and is dried in contact with a polished smooth surface.
One of the major disadvantages of the current inkjet recording element is “differential gloss”, particular on images printed using pigment-based inks. In pigment-based inks, the colorant exists as discrete particles. These pigment particles are usually treated with addenda known as dispersants or stabilizers which serve to keep the pigment particles from agglomerating and/or settling out. Therefore, when the pigment-based inks are printed on recording elements having glossy surfaces, the inks on the imaged areas tend to stay on the surface of the receiver. “Differential gloss” describes the image artifact where the gloss of the non-imaged areas is very different from that of imaged areas. This type of image quality defects can be quite noticeable, even to ordinary observers. Although not designed to improve “differential gloss”, one possible solution to this problem is to cover the entire receiver with a protective layer through techniques such as laminating the printed image, or fusing the top fusible polymeric layer in receivers to a continuous overcoat layer, such as those disclosed in U.S. patent application Ser. No. 09/954,779, filed on Sep. 18, 2001 of Wexler, or coating a protective layer on the imaged areas as described in EP1057646 and EP1048466. However, all these approaches involve separate steps after printing, making the entire process complex and costly.
What the art needs is a way to minimize gloss level variations in imaged and non-imaged areas when the various inks are deposited and dried on a receiver. This should be done as part of the printing process and not as a separate step after printing.
SUMMARY OF THE INVENTION
The present invention provides an inkjet color ink set and receiver combination that is capable of producing images wherein the gloss level variations between imaged and non-imaged areas are minimized. The gloss variation is judged after the ink is deposited and dried on a receiver, but the invention is a part of the ink and receiver selection and printing process; not a separate step after printing.
In accordance with the invention, the gloss level of the ink is predetermined, as measured from single color patches on a receiver. The gloss level of the receiver is also determined under a similar measurement condition. The relative gloss difference between the imaged and non-imaged areas is calculated. By keeping the relative gloss difference of the ink and receiver combination within a certain range, quality of the image is improved.
Hence, the present invention discloses an ink jet ink set and recording element combination comprising:
A) a porous inkjet recording element having a 60° specular gloss of at least about 5; and
B) a pigment based ink jet ink set comprising at least two inks; wherein the RGD value is less than 40% when 60° is used as the specular angle and the RGD value is calculated according to Equation (A):
RGD
%
=
∑
I
=
1
N
&LeftBracketingBar;
Gloss
(
Imaged
Areas
)
I
-
Gloss
(
Non
Imaged
Areas
)
&RightBracketingBar;
∑
I
=
1
N
Gloss
(
Imaged
Areas
)
I
Equation
(A)
Where
I is a variable which identifies a certain color patch used in the evaluation,
N is the total number of color patches used in the evaluation.
The advantage of the invention is that it minimizes gloss difference between the imaged and non-imaged areas in a printed color image on the receiver and this is done as a part of the initial printing process.
Detailed Description of the Invention
Ink Set and Receiver Gloss Matching
Gloss, commonly referred to as specular gloss, of a surface is defined as its degree of approach to a mirror-like surface. It is a measure of the amount of energy reflected at a reflection angle equal to or near the angle of incidence. Specular gloss can be measured in terms of gloss units, at several angles, e.g. 20°, 30°, 45°, 60°, 75° and 80° from the surface normal. Gloss meters are used to measure the gloss of a sample at various angles. The BYK-Gardner micro-TRI-glossmeter is an example of such an instrument.
The porous receiver used in this invention refers to an ink-recording element having a 60° specular gloss level of 5 or higher. An ink jet recording element typically comprises a support having on at least one surface thereof an ink-receiving or image-forming layer, the ink-receiving a porous layer which imbibes the ink via capillary action. The gloss level of the receiver can be achieved through receiver layer design and the properties of components in each layer, such as particle sizes of the surface coating, surface roughness of the support, etc. For example, possibly by varying the inorganic particle sizes in the ink receiving layer, 60° gloss level of Kodak Instant-Dry Photographic Glossy Media Cat 8103137 has reached a value of about 64. In comparison, the 60° gloss level of Epson Photoglossy Paper® SP91001 is only about 34. In addition, as known in the art, gloss level can also be modified by changing the surface smoothness of support. For example, by changing the surface smoothness of the chill roll (e.g. a F-surface versus a textured E-surface) used in the resin coating step of the support manufacturing, Kodak Instant-Dry Photographic media has a wide range of gloss level from a 60° gloss level of about 30 (Satin Media Cat 8648263) to that of 64 (Glossy Media Cat 8103137).
When inks are printed on a receiver, the gloss level of the printed image is determined by both ink and receiver. Ink properties, such as, for example, the refractive index of polymers in the inks, the film forming property of the polymers in the inks after printing, and the ink load deposit on the receiver, may individually or in combination influence the gloss of a printed image. For pigment-based inks, pigment particle size and distribution, and the use of non-film forming particles can also have a significant impact on the gloss levels, such as those disclosed in U.S. patent application Ser. No. 10/034,721 (Docket 83710) INK JET INK SET, filed herewith of Chen et al.
The present inventors have discovered that when the gloss level of the receiver is designed to match the gloss levels generated from the ink set, the printed images have less observable differential gloss, thus improve the image quality of the overall print. In this invention, the match is characterized by a parameter called Relative Gloss Difference (RGD %) as defined in Equation A. The present invention further discloses that when the value of
Chen Huijuan D.
Han-Adebekun Gang C.
Reczek James A.
Meier Stephen
Shah Manish
Wells Doreen M.
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