Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
2000-05-31
2003-11-18
Jones, Deborah (Department: 1775)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
C428S205000, C428S207000, C428S211100, C428S212000, C428S213000, C428S500000, C428S321300
Reexamination Certificate
active
06649249
ABSTRACT:
FIELD OF INVENTION
This application relates to inkjet printing media to improve drying times of the inkjet ink, improve abrasion resistance of the inkjet image after drying, and prevent visual defects caused by ink beading, ink spreading, or mudcracking, resulting in improved print quality.
BACKGROUND OF INVENTION
Image graphics are omnipresent in modern life. Images and data that warn, educate, entertain, advertise, etc. are applied on a variety of interior and exterior, vertical and horizontal surfaces. Nonlimiting examples of image graphics range from advertisements on walls or sides of trucks, to posters that advertise the arrival of a new movie, warning signs near the edges of stairways, and the like.
The use of thermal and piezo inkjet inks has greatly increased in recent years with accelerated development of inexpensive and efficient inkjet printers, ink delivery systems, and the like.
Thermal inkjet hardware is commercially available from a number of multinational companies, including without limitation, Hewlett-Packard Corporation of Palo Alto, Calif.; Encad Corporation of San Diego, Calif.; Xerox Corporation of Rochester, N.Y.; ColorSpan Corporation of Eden Prairie, Minn.; and Mimaki Engineering Co., Ltd. of Tokyo, Japan. The number and variety of printers change rapidly as printer makers are constantly improving their products for consumers. Printers are made both in desk-top size and wide format size depending on the size of the finished image graphic desired. Nonlimiting examples of popular commercial scale thermal inkjet printers are Encad Corporation's NOVAJET PRO printers and Hewlett-Packard's 650C, 750C, and 2500CP printers. Nonlimiting examples of popular wide format thermal inkjet printers include Hewlett-Packard Corporation's DesignJet printers, where the 2500CP is preferred because it has 600×600 dots/inch (dpi) resolution with a drop size in the vicinity of about 20 picoliters (pL).
Minnesota Mining and Manufacturing Company (3M) of St. Paul, Minn. markets GRAPHIC MAKER INKJET software useful in converting digital images from the Internet, ClipArt, or Digital Camera sources into signals to thermal inkjet printers to print such image graphics.
Inkjet inks are also commercially available from a number of multinational companies, particularly Minnesota Mining and Manufacturing Company which markets its Series 8551; 8552; 8553; and 8554 pigmented inkjet inks. The use of four process colors: cyan, magenta, yellow, and black (generally abbreviated “CMYK”) permit the formation of as many as 256 colors or more in the digital image.
Media for inkjet printers are also undergoing accelerated development. Because inkjet imaging techniques have become vastly popular in commercial and consumer applications, the ability to use a personal computer to print a color image on paper or other receptor media has extended from dye-based inks to pigment-based inks. The media must accommodate that change. Pigment-based inks provide more durable images because of the large size of colorant as compared to dye molecules.
Inkjet printers have come into general use for wide-format electronic printing for applications such as engineering and architectural drawings. Because of the simplicity of operation and economy of inkjet printers, this image process holds a superior growth potential promise for the printing industry to produce wide format, image on demand, presentation quality graphics.
Therefore, the components of an inkjet system used for making graphics can be grouped into three major categories:
1. Computer; software, printer
2. Ink
3. Receptor medium
The computer, software, and printer will control the size, number and placement of the ink drops and will transport the receptor medium through the printer. The ink will contain the colorant which forms the image and carrier for that colorant. The receptor medium provides the repository which accepts and holds the ink. The quality of the inkjet image is a function of the total system. However, the compositions and interaction between the ink and receptor medium are most important in an inkjet system.
Image quality is what the viewing public and paying customers will want and demand to see. From the producer of the image graphic, many other obscure demands are also placed on the inkjet media/ink system from the print shop. Also, exposure to the environment can place additional demands on the media and ink (depending on the application of the graphic).
Current inkjet receptor media, direct coated with compositions according to the disclosure-contained in U.S. Pat. No. 5,747,148 (Warner et al.) and in PCT Patent Publication Nos, WO 99/07558 (Warner et al.) and WO 99/03685 (Waller et al.), are marketed by Minnesota Mining and Manufacturing Company under the brands 3M™ Scotchcal™ Opaque Imaging Media 3657-10 and 3M™ Scotchcal™ Translucent Imaging Media 3637-20, 8522, and 8544, respectively. Another inkjet receptor media is disclosed in PCT Patent Publication No. WO 97/33758 (Steelman et al.) which combines a hygroscopic layer on a hydrophilic microporous media.
Inkjet inks are typically wholly or partially water-based, such as disclosed in U.S. Pat. No. 5,271,765. Typical receptors for these inks are plain papers or preferably specialty inkjet receptive papers which are treated or coated to improve their receptor properties or the quality of the images resulting therefrom, such as disclosed in U.S. Pat. No. 5,213,873.
Many inkjet receptor compositions suitable for coating onto plastics to make them inkjet receptive have been disclosed. Typically these receptor layers are composed of mixtures of water-soluble polymers which can absorb the aqueous mixture which the inkjet ink comprises. Very common are hydrophilic layers comprising poly(vinyl pyrrolidone) or poly(vinyl alcohol), as exemplified by U.S. Pat. Nos. 4,379,804; 4,903,041; and 4,904,519. Also known are methods of crosslinking hydrophilic polymers in the receptor layers as disclosed in U.S. Pat. Nos. 4,649,064; 5,141,797; 5,023,129; 5,208,092; and 5,212,008. Other coating compositions contain water-absorbing particulates such as inorganic oxides, as disclosed in U.S. Pat. Nos. 5,084,338; 5,023,129; and 5,002,825. Similar properties are found for inkjet paper receptor coatings, which also contain particulates, such as cornstarch as disclosed in U.S. Pat. Nos. 4,935,307 and 5,302,437.
The disadvantage that many of these types of inkjet receptor media suffer for image graphics is that they comprise water-sensitive polymer layers. Even if subsequently overlaminated, they still contain a water-soluble or water-swellable layer. This water-sensitive layer can be subject over time to extraction with water and can lead to damage of the graphic and liftoff of the overlaminate. Additionally, some of the common constituents of these hydrophilic coatings contain water-soluble polymers not ideally suitable to the heat and UV exposures experienced in exterior environments, thus limiting their exterior durability. Finally, the drying rate after printing of these materials appears slow since until dry, the coating is plasticized or even partially dissolved by the ink solvents (mainly water) so that the image can be easily damaged and can be tacky before it is dry.
In recent years, increasing interest has been shown in microporous films as inkjet receptors to address some or all of the above disadvantages. Both Warner et al. and Waller et al. publications and Steelman et al. application identified above disclose microporous films to advantage. If the film is absorbent to the ink, after printing the ink absorbs into the film itself into the pores by capillary action and feels dry very quickly because the ink is away from the surface of the printed graphic. The film need not necessarily contain water-soluble or water-swellable polymers, so potentially could be heat and UV resistant and need not be subject to water damage.
Porous films are not necessarily receptive to water-based inkjet if the material is inherently hydrophobic and methods of making them hydrophilic have been e
Engle Lori P.
Fehr Robert T.
Fleming Patrick R.
Graham Paul D.
Huntley Douglas A.
3M Innovative Properties Company
Jones Deborah
Pribnow Scott R.
Xu Ling
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