Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
2002-01-29
2004-06-22
Dicus, Tamra (Department: 1774)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C428S195100, C428S213000, C428S220000, C428S221000, C428S357000
Reexamination Certificate
active
06753080
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the use of microfibers and/or microflakes as receptor media for a printable substrate. The printable substrate includes an oriented film with at least one microfibrillated, ink receptive surface. Printing on such receptor media with inkjet printers provides fine-resolution images with good solid fill. This type of printable substrate can be used with many types of inkjet inks.
BACKGROUND OF THE INVENTION
Image graphics are omnipresent in modem 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 piezoelectric inkjet inks has greatly increased in recent years with accelerated development of inexpensive and efficient inkjet printers, ink delivery systems, and the like.
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).
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, which results in superior fade resistance and improved water fastness.
Inkjet printing is emerging as the digital printing method of choice due to its good resolution, flexibility, high speed, and affordability. Inkjet printers operate by ejecting, onto a receiving substrate, controlled patterns of closely spaced ink droplets. By selectively regulating the pattern of ink droplets, inkjet printers can produce a wide variety of printed features, including text, graphics, holograms, and the like. The inks most commonly used in small inkjet printers, such as those used in the small office and home office (SOHO) markets, are water based. Industrial type wide format inkjet printers can use water based inks such as the Novajet printers from Encad Inc. (San Diego, Calif.), oil based inks such as piezo print 5000 from Raster Graphics Inc. (San Jose, Calif.), solvent based inks such as the PressVu printers from VUTEk, Inc. (Meredith, N.H.), or UV curable inkjet inks such as the SIAS printer from Siasprint Group (Novara, Italy). This wide variety of inks typically requires specialized substrates, where each specific substrate is optimized to work with a specific type of inkjet ink. For example, water based inks require porous substrates or substrates with special hydrophilic coatings that absorb the large quantities of water contained in these inks. Oil based inks are similar to water based inks in that they require the use of either porous substrates or substrates coated with a receptor that is oil absorbing.
On the other hand, solvent based inks typically contain about 90% organic solvents. These inks work well on substrates that have high affinity to the solvents, where the solvents can quickly penetrate the polymeric film preventing the printed ink layer from running down the film. In high speed inkjet printing, there is a need to drive off large quantities of solvent so that the substrate is dry enough to be rolled without blocking in a relatively short period of time. Therefore, typical solvent based inkjet inks consist of aggressive solvents such as cyclohexanone and acetates that penetrate quickly into typical films such as vinyl giving the printed graphic a “dry” feel within a short period of time from printing. As a consequence, the quickly penetrating solvents tend to remain in the film (as well as in the PSA backing if present) resulting in deteriorated film properties, reduced PSA performance, and strong odor when the graphic is unrolled and applied to a flat surface.
In particular, most wide format solvent based piezo inkjet inks require a very low viscosity for jetting, resulting in a very high ratio of solvent to binder/pigment. Large amounts of ink must be jetted onto the desired substrate to produce a graphic with acceptable image density. Polyvinyl chloride (PVC) is typically used for producing large format durable graphics. The solvents used in the inks are quickly absorbed into the vinyl film and adhesive layers, leaving the pigment and binder on the surface of the film and resulting in acceptable image quality. The piezo ink solvents are very compatible with the PVC and adhesive layers, and also have relatively high boiling points so it is difficult to fully dry all of the solvent from a printed sample, especially with the constraints typical of a graphic production shop. The presence of the retained solvent negatively affects product performance in three ways: 1) the solvents migrate through the PVC and plasticize the adhesive which results in very poor adhesive performance, 2) the solvents are retained in the PVC film layer resulting in decreased film properties, and 3) the retained solvents in the film and adhesive have an objectionable odor which is very noticeable especially on large format graphics, and has been noted as objectionable by a number of customers. Traditional olefin-based graphic films can work well for screenprint and flexographic printing, but have problems with solvent based piezo inks because the large amount of solvents jetted cannot be absorbed into the film. When large amounts of piezo inkjet inks are printed onto traditional olefin based graphic films the inks pool on the surface of the film and readily run, producing a poor quality, distorted image. There is a need for a substrate that is receptive to solvent based piezo inkjet inks, does not allow running of the inks, provides good adhesion of the inks when dry, and dries quickly to prevent objectionable odors.
In order to avoid the challenges associated with the above-described inks, there is a drive in the marketplace to move towards UV curable inkjet inks. These inks are expected to provide an “instant dry” feature when exposed to UV radiation. However, the use of UV curable inkjet inks requires redesigning the printer to accommodate curing lamps. This increases the cost of the printer. Additionally, there is an inherent problem with UV curable inkjet inks: in order to obtain fine line resolution, the inks should be cured within a relatively short time from printing, which results in poor ink flow and leveling compromising the quality of the solid fill areas of the graphic. But to obtain good
Ernslander Jeffrey O.
Hobbs Terry R.
Kody Robert S.
Perez Mario A.
Sebastian John M.
3M Innovative Properties Company
Dicus Tamra
Kelly Cynthia H.
Kokko Kent S.
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