Stock material or miscellaneous articles – Ink jet stock for printing – Retransferable
Reexamination Certificate
1998-02-25
2004-11-30
Hess, B. Hamilton (Department: 1774)
Stock material or miscellaneous articles
Ink jet stock for printing
Retransferable
C347S105000, C428S032240, C428S032250, C428S032340
Reexamination Certificate
active
06824839
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to materials which are ink jet imprintable and that can be used for adhesive image transfer, and constructions made with such materials.
BACKGROUND OF THE INVENTION
Labels, tapes and similar constructions are ubiquitous in modern society. Many such constructions include a release liner coated with an adhesive, such as a pressure-sensitive adhesive (PSA), which is laminated to a paper or film face stock. Removal of the release liner allows the construction to be adhered to a substrate. The face stock and liner are a major cost of the label.
Many adhesives, such as those commonly used in label constructions, are not water dispersible or repulpable. Therefore, they make recycling of the label product difficult, due to the tendency of the adhesives to form globules during the repulping process. In addition, most PSAs are tacky when dry and cannot readily be used with ink jet printers that have become so popular in today's world. Moreover, such PSAs typically are not hydrophilic, making it difficult to directly print on them directly with water-based ink jet printer inks. Instead, only the face stock or liner is ink receptive. The unsuitability of such PSAs for use in ink jet printers is compounded by the tendency of the adhesives to block the printer ports in the printers.
Although attempts have been made to formulate moisture activated or water activated adhesives, many of the adhesives produced have been rubber based and, therefore, subject to oxidative and UV degradation. Other adhesives have been solvent borne, and thus objectionable for environmental, health and safety reasons. The following patents are representative. U.S. Pat. No. 3,681,179 to Theissen discloses a solar control film construction having a water-activatable adhesive system comprising a normally tacky and pressure-sensitive adhesive coating covered by a thin, tack-free continuous water-soluble layer. A tack free emulsion acrylic adhesive is not disclosed.
European Pat. Nos. 199,468 and 297,451 describe a method for compounding water-activatable hot melt adhesives comprising polyaklylenimine or other vinyl heterocyclic monomers, a hydroxy-substituted organic compound, a plastizier, tackifier, and filler, and an antioxidant. No mention is made of making water activatable emulsion acrylic adhesives.
U.S. Pat. Nos. 4,331,576 and 4,325,581 to Colon et al. disclose common water-soluble hot melt adhesives based on polymers containing vinyl pyrrolidone and other heterocyclic monomers. Emulsion acrylics are not disclosed.
U.S. Pat. No. 4,052,368 to Morrison and U.S. Pat. No. 4,172,824 to Harrington describe water sensitive hot melt adhesives including polyester-based adhesives which typically comprise a copolyester in combination with a plasticizier. The systems are not emulsion acrylics.
None of the above-identified patents disclose or suggest the possibility of making a hydrophilic, acrylic emulsion polymer that is non-tacky when dry and water activated to become an adhesive, and that can be used in a “label-less” or “liner-less” construction, i.e., a construction in which either a face stock or liner is not required
Many arrangements for the transfer of images from ink jet printers are known. For example, images, including printing, may be printed onto labels having pressure sensitive adhesive on the labels, and these labels may be applied to a desired substrate, such as a bottle or other product.
SUMMARY OF THE INVENTION
In accordance with the present invention, it has been determined that some unique benefits may be obtained by imaging onto a polymer layer, coated on an opaque or transparent plastic sheet, such as MYLAR™, as a base layer, using an ink jet printer.
A conventional ink jet printer is employed to apply an ink image, preferably a colored image, to the adhesive layer of an image transfer sheet, the adhesive layer having been coated onto a base layer which is preferably flexible and nonporous to an ink jet printer ink. The non-porous flexible layer may be a sheet of plastic which can be either opaque or transparent.
The adhesive layer is compatible with and will absorb an ink jet printing ink. Most inks used in ink jet printers are water based, but such inks may also be based on organic solvents or carriers for the ink dyes and/or pigments. Thus, depending upon the ink used in the ink jet printer, the adhesive layer may be either hydrophilic or hydrophobic. Since, as noted above, most ink jet printing inks are water based, it is generally preferable if the adhesive coating or layer, at the time of imaging, is hydrophilic and will absorb the water-based ink.
Water-based inks for ink jet printers are well-known in the art and therefore no detailed exemplification thereof will be given herein. These water-based inks contain a sufficient amount of water to be the carrier for the dyes and/or pigments in the ink. Of course, a water-based ink jet printing ink may contain water-miscible organic liquids such as polyhydric alcohols which are often present in water-based inks to prevent clogging of the nozzles. The inks may also contain a variety of other compounds such as surfactants, etc.
At the time of printing the ink on and into the adhesive layer to form an image, the adhesive layer should be detackified. After the adhesive layer is imaged, it will then be activated, i.e. the adhesive layer tackified to a tacky state, and adhered or bonded to any desired substrate such as a ring binder, clothing, notebook cover, a glass window, a wall or anywhere it is desired to view the image. In this regard, it should be noted that if the image is placed or adhered to a non-transparent substrate, and the base layer is not transparent, the adhesive layer should be releasably bonded to the base layer so that the base layer can be removed to allow the image to be seen by a viewer. From the foregoing, it is apparent that the image is viewable from both the lower surface (i.e. the surface facing the base layer) and the upper surface (i.e. the surface facing away from the base layer) of the adhesive coating or layer.
The ink absorbing adhesive layer used in the present invention may be pressure sensitive, particularly hydrophilic pressure sensitive adhesives. Such adhesives are known in the art and include repulpable pressure sensitive adhesives such as those disclosed in U.S. Pat. Nos. 5,196,504 and 5,326,644, such disclosures being incorporated herein by reference. The adhesives disclosed in these patents are water-dispersible and tacky at room temperature which make them ideal for use in the present invention. Of course, other pressure sensitive hydrophilic adhesives are also known in the art and they too are suited for use in the present invention.
If an adhesive is used which is tacky at the time when it is imaged, the adhesive may be detackified by providing the imaging transfer sheet with an outer detackifying layer over the upper surface of the adhesive coating. Such a detackifying layer will be porous to the imaging ink so that a sufficient amount of ink will pass through the porous detackifying layer to the adhesive layer to allow an image to be formed therein. Generally speaking, the detackifying layer will permit at least 30 percent and preferably more (e.g. 40 percent) of the ink jet printing ink to pass into the adhesive layer and form an image.
Various types of porous detackifying layers may be used. For example, a mesh coating such as cheesecloth may be used, preferably with a very thin layer of release material such as silicone between the mesh layer and the adhesive, preferably coated on the mesh before it is applied to the adhesive so that the mesh layer may be more readily removed. It is emphasized that the silicone layer does not cover the pores of the mesh, thereby allowing the ink to pass through the pores of the mesh and into the pressure sensitive adhesive. Other mesh materials having finer strains and being less coarse than cheesecloth may be employed. Even paper may be employed since it is porous to the ink.
Other porous detackifying outer layers whic
Barker H. Paul
Kubit Raymond
Miekka Fred
Popat Ghanshyam H.
Ray Gustav
Avery Dennison Corporation
Fulwider Patton Lee & Utecht LLP
Hess B. Hamilton
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