According to the present invention the above mentioned problem is solved and it is possible to produce linerless postage stamps which have a top face that will appropriately hold cancellation ink when applied in a cancellation pattern so that the cancellation pattern is visible and will not wipe off during normal handling. Basically this is accomplished according to the present invention by providing a barrier coat on the top layer of a paper substrate. While the barrier coat seals off the paper it also creates an uneven surface so that the release material can sink into the substrate as well as allowing the ink from the cancellation pattern to sink into the

paper. The release layer must allow the ink to pass into the substrate sheet (typically paper) while at the same time providing sufficient release characteristics so that the adhesive from one stamp will not stick to the top face of another. Also the surface of the stamp must be smooth enough to allow processing through conventional high speed equipment.

According to one aspect of the present invention a method of making a linerless postage stamp from a sheet or web having top and bottom faces, is provided. The method comprises the steps of: (a) Applying a porosity enhancing or release coat absorption enhancing barrier coat to the top face of the sheet or web. (b) Applying a pressure sensitive adhesive to the bottom face. (c) Applying an adhesive release material, which does not stick to the adhesive in step (b), to the barrier coat from step (a). And, (d) forming the web or sheet into separable postage stamps with postage stamp indicia on the top face. And, wherein steps (a) and (b) are practiced to provide sufficient porosity to the top face so that it can absorb or otherwise retain sufficient stamp cancellation ink so that the ink is visible on the top face once applied and dried.

Step (d) may be practiced by (d1) applying postage stamp indicia to the top face prior to the practice of step (a), and (d2) forming lines of weakness in the sheet or web to define the boundaries of separable individual stamps. Step (d2) is typically practiced before steps (b) and (c), but can be practiced at any stage in the method, including after all of steps (a) through (c).

Step (a) is typically practiced by applying a styrene acrylic latex as a barrier coating (e. g. available from Northwest Coatings Corp., Northwest Aqueous Barrier Coating, no. 20951), with a weight of between about. 7-. 85 85 pounds per ream (e. g. about. 70-. 80 pounds per ream). A "ream"as used in the present specification and claims refers to the

amount of substrate or paper that is, or is equivalent to, 500 sheets of 17 inch x 22 inch paper.

Step (b) is typically practiced by applying as the release coat UV curable silicone at a weight of between about. 4-. 5 pounds per ream. The method may also comprise the further step of forming the sheet or web into a roll configuration.

The method as described above may also be practiced so that the stamp made is a canceled stamp, in which case the method comprises the further steps of applying the adhesive on the bottom face to a mailing piece, and applying cancellation ink in the form of a cancellation image to the top surface of the stamp so that a sufficient quantity of the ink is absorbed or otherwise retained by the top surface so that the cancellation image is visible and is not easily wiped off during automated processing, and manual handling, of the mailing piece.

According to another aspect of the present invention there is provided a canceled postage stamp comprising: A substrate having top and bottom surfaces. Postage stamp indicia imaged on the top face. A porosity enhancing or release material absorption enhancing barrier coat on the top face. An adhesive release coat over the barrier coat. A pressure sensitive adhesive coating the bottom face. Stamp cancellation ink in a cancellation pattern on the release coat. And, the barrier coat properties and coating weight, and the release material properties and coating weight, being such that the stamp cancellation ink is absorbed or otherwise retained by the top face so that the stamp cancellation pattern is readily visible and the ink is not easily wiped off, and the adhesive will not adhere to the top face.

The specific barrier coat for the canceled stamp, and its application weight, are preferably as described above. The release coat is preferably

UV cured silicone applied at a weight of between about. 4-. 5 pounds per ream, but may be water-based, thermally cured silicone under some circumstances. The substrate preferably is about 20-28 pounds per ream paper, such as 24 pound paper available from Union Camp. The adhesive may be hot melt adhesive, or another conventional type permanent pressure sensitive adhesive, or under some circumstances may comprise a removable adhesive or repositional adhesive (such as "CLEANTAC 3"adhesive available from Moore U. S. A. of Lake Forest, Illinois).

According to another aspect of the present invention a postage stamp is provided comprising: A paper substrate having top and bottom faces. A pressure sensitive adhesive on the bottom face. Postage stamp indicia on the top face. A styrene acrylic latex formation barrier coat applied to the top face in an amount between about. 7-. 8 pounds per 17 inch x 22 inch x 500 sheet ream of substrate sheets. And a UV curable silicone release material applied over the barrier coat at a weight between about. 4-. 5 5 pounds per 17 inch x 22 inch x 500 sheet ream of substrate paper.

According to yet another aspect of the present invention a linerless postage stamp assembly is provided comprising: A web of a plurality of postage stamps comprising a substrate material with pressure sensitive adhesive on a first face, and having a second face having release material which will not adhere to the adhesive but will absorb or otherwise retain stamp cancellation ink substantially permanently in sufficient quantity so that a cancellation pattern thereof is clearly visible. And, the web is a roll configuration with adhesive of one stamp engaging release material of another.

It is the primary object of the present invention to provide a linerless postage stamp that can effectively retain the cancellation pattern applied thereto. This and other objects of the invention are apparent from the description herein and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a schematic illustration of the exemplary method steps according to the present invention; FIGURE 2 is a side schematic view, with the components greatly exaggerated in size for clarity of illustration, of an exemplary linerless postage stamp according to the invention; FIGURE 3 is a top perspective view of a sheet of individual stamps according to the present invention; FIGURE 4 is a side schematic illustration of a postage stamp assembly according to the present invention in a rolled configuration; and FIGURE 5 is a top detail view of an envelope with canceled stamp according to the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS FIGURE 1 schematically illustrates an exemplary method according to the present invention in which a web or sheet 10 is acted upon to produce postage stamps. The web or sheet 10 forms the substrate for the postage stamps ultimately produced and preferably is of paper or a material with porosity similar to paper. Most desirably the paper has a weight of between about 20-28 pounds per ream, e. g. about 24 pound Union Camp paper.

Typically the first step in the practice of the method schematically illustrated in FIGURE 1 (although many of the steps may be revised in order) is the application of postage stamp indicia as indicated by box 11 in FIGURE 1 to the top face of the web or sheet 10. Then a barrier coat is applied over the postage stamp indicia, as indicated by step 12, and the release coat material is applied over the barrier coat as indicated at 13.

The step indicated by box 12 is preferably practiced utilizing a styrene acrylic latex formulation as the barrier coating, although any other barrier coat that sufficiently enhances the porosity, or release coat absorption, of the top face of the sheet or web 10 may be utilized. One exemplary commercially available material is product no. 20951 or 20951A, available from Northwest Coatings. A comparison of some physical properties of these chemicals is as follows: 20951 20951A Brookfield Viscosity @ #2 Spindle, RVF, 900-1400cps 900-1400cps 75-77°F., 20 RPM pH 8.0-9.0 8.75-9.25 Solids 36-39% 35-39% The barrier coat step is typically practiced, as indicated in box 12, by applying about. 7-. 85 pounds per ream (e. g. between about 0.72-. 80 pounds per ream) in a uniform manner. The release coat applied at box 13 in FIGURE 1 preferably is a UV curable silicone, such as General Electric Silicone 9300, or Goldschmidt Silicone 70% RC-711 and 30% RC-726.

Step 11 is typically practiced by a press or other imaging device, while steps 12 and 13 may be practiced utilizing flexographic techniques, a Gravure press, or a conventional Meyer rod.

The method of FIGURE 1 also includes--as indicated by box 14-- application of pressure sensitive adhesive to the bottom face of the web or sheet 10. The pressure sensitive adhesive that is applied in box 10 may be any suitable conventional pressure sensitive adhesive, preferably a permanent adhesive like hot melt adhesives (such as Findley 2181), although it also may be a removable or repositional adhesive (such as CLEANTAC 3 adhesive available from Moore U. S. A.). The adhesive may be water-based instead of hot melt, and is applied to the bottom face of the web or sheet 10 using any suitable conventional technique, such as via a slot die.

Box 15 in FIGURE 1 indicates the formation of the web or sheet 10 into individual separable stamps. Step 15 may be practiced before step 11, or at almost any other place in the process, and is practiced by providing lines of weakness (such as conventional stamp perforations, die cuts, or the like) in the web or sheet 10 utilizing conventional perforating or die cutting equipment or the like.

After the linerless stamps are produced, they may be formed into a roll or stack as indicated by box 16 in FIGURE 1. The roll may be formed by slitting the stamps along the direction of movement of the web or sheet 10 during the practice of the steps 11 through 15, so that the roll is only one stamp wide. The stacking of the sheets may be formed by any conventional technique, and the web may be cut into individual sheets with a plurality of stamps in each sheet before they are stacked.

The roll or stack formed in step 16 is utilized by separating individual stamps from the roll or stack as indicated schematically by box

17 in FIGURE 1. The separation may be manually or utilizing conventional automatic equipment. The separated stamp is applied to a mail piece, as indicated at box 18 in FIGURE 1, such as an envelope, package, or postcard. The mail piece is mailed and ultimately the stamp is canceled--as indicated by box 19 in FIGURE 1--utilizing conventional automatic USPS stamp canceling equipment. The stamp canceling equipment applies a cancellation pattern, with cancellation ink, to the top face of the stamp, while the pressure sensitive adhesive on the bottom face of the stamp is adhered to the mail piece.

FIGURE 2 is a side cross-sectional view, with the elements thereof greatly exaggerated in thickness and contour for clarity of illustration, of an exemplary linerless stamp according to the invention. The stamp 20 comprises a substrate 21, preferably about 20-28 pound per ream of paper, with a top face 22 and a bottom face 23. On the bottom face 23 is a layer of conventional pressure sensitive adhesive 24, such as hot melt adhesive. On the top face 22 is postal stamp indicia, indicated by reference numeral 25, which typically includes the amount of postage and some sort of design. Applied over the indicia 25 and in contact with the top face 22 is the barrier coat material 26, such as the Northwest Coatings 20951 material earlier described. The material 25 has a relatively uneven surface, as indicated schematically at 27 in FIGURE 2, and functions to enhance the porosity, or release coat absorption, of the top face 22 of the stamp 20.

Applied over the barrier coat 26 is the release material 28, such as a conventional UV curable silicone as described above, or water-based thermally cured silicone.

Typically the barrier coat 26 has a weight of about. 7-. 85 pounds per ream, e. g. between about 0.72-. 80 pounds per ream, while the

silicone coating 28 has a weight of between about 04-0.5 pounds per ream.

FIGURE 3 illustrates a sheet 30 of individual stamps 20 according to the invention, each of the individual stamps 20 being separated from each other by conventional lines of weakness 31, in this case perforation lines. The upper left corner of the cut off end of the sheet 30 is shown turned back to illustrate the pressure sensitive adhesive 24 on the bottom face 23 thereof. When the sheets 30 are stacked in a stack, the pressure sensitive adhesive 24 from one sheet 30 will not adhere to the release coat 28 on the underlying sheet 30.

FIGURE 4 schematically illustrates a postage stamp assembly according to the present invention in roll configuration, shown generally by reference numeral 34 in FIGURE 1. The roll is one stamp wide with each of the stamps 20 again being separated by lines of weakness such as perforation lines 31. In the roll configuration 34 the pressure sensitive adhesive 24 from the outer stamps engage the release coat 28 of the inner stamps, and they do not stick together.

FIGURE 4 also schematically illustrates a postage stamp 20 being applied to a mail piece 35, such as an envelope, package, or postcard.

The pressure sensitive adhesive 24 of the stamp 20 is applied to the addressed surface 36 of the mail piece 35, pressure causing the adhesive 24 to securely adhere to the face 36, and in fact permanently adhere if the adhesive 24 is a permanent adhesive, such as Findley 2181. The mailing piece 35 is subsequently mailed, and processed by the USPS.

During processing, utilizing conventional equipment, a cancellation pattern is applied over the stamp 20 using cancellation ink. For example FIGURE 5 shows a canceled version 20'of the stamp 20 of FIGURE 4 on the mailing piece 35 after the cancellation pattern/ink 38 is applied

thereto. Because of the properties of the top surface 22, as modified by the particular application of the barrier coat 26 and the release material 28 according to the invention, the cancellation pattern/ink 38 is clearly visible on the stamp 20', and is not easily wiped off during automated processing and the manually handling of the mailing piece 35.

The cancellation ink in pattern 38 is typically that available from American Coding and Marking Co. referenced as USPS 914M2B Cancellation Ink.

While the invention has been herein shown and described in what is presently conceived to be the most practical and preferred embodiment it is apparent to those of ordinary skill in the modified that many modifications may be made thereof within the scope of the invention which scope is to be accorded the broadest interpretation of the appended claims so as to encompass all equivalent processes and products.