Patent Application
20050226672
1. Field of the Invention
This invention relates to printers for handling webs including linerless webs having tacky adhesive, methods associated with the handling of such webs, rolls including platen rolls, and methods of making rolls.
2. Brief Description of the Prior Art
The following documents are made of record: U.S. Pat. Nos. 5,267,800; 5,497,701; 5,833,377; 6,585,437; U.S. patent application Ser. No. 10/266,060, filed Oct. 7, 2002; and Linerless Addendum, Monarch Marking Systems, Inc. 1998.
The present invention relates to improved method and apparatus to strip a tacky adhesive-backed web from a roll reliably.
It is a feature of the invention to provide an improved printer for handling linerless, tacky, adhesive-backed webs wherein the webs are reliably stripped from a roll.
It is a feature of the invention to provide an improved printer for printing on a linerless web backed by a tacky adhesive which has a thermal print head and an adhesive-resistant, elastomeric, rotatable platen roll with a web stripper having at least one tip portion to cut at least one circumferential groove in the outer surface of the platen roll upon rotation of the platen roll. Initially, the tip portion or portions are positioned to dig or locally press into the elastomer platen roll. Upon rotation of the platen roll, a circumferential groove or grooves are cut in the surface of the platen roll. From the very beginning, the stripper causes the web to be reliably stripped from the roll. Repeated rotation of the platen roll completes the formation of the groove or grooves as the elastomeric material is cut and/or abraded away. After the groove or grooves have been cut, the linerless web continues to be reliably stripped from the web.
It is apparent that the groove or grooves are no wider or deeper than the tip portions that penetrate into the elastomeric material below the outer surface. Indeed, the tip portions “write their own name” in the platen roll, and the grooves are perfectly aligned with the tip portions which formed the grooves.
It is a feature of the invention to provide a stripper with one or more tip portions or cutters which serve to help strip the tacky, adhesive-backed web from the roll and which also function to make the groove(s) in the roll.
It is a feature of the invention to provide an improved, low friction shelf for a linerless printer which is relatively wide but which is rigid enough to resist flexure during use so that a linerless tacky adhesive-backed web is incapable of bowing the shelf and following the platen roll around.
With reference to
The web 10 has an upper face 11 with the usual coatings such as a thermal coating, an optional barrier coating and a silicone coating. The underside of the web 12 has a coating of adhesive 14 which can be uniform and continuous as shown, which is known as a “full gum” coating, but the coating of adhesive 14 can be patterned or a “part gum” coating which is useful in certain applications. The adhesive 14 is of the tacky type also known as “pressure sensitive adhesive” because it adheres to a surface when pressure is applied. Tacky adhesive is sticky or tacky without activation by heat, water or other medium.
Because rolls that are to be in contact with adhesive on one side of a linerless web are typically adhesive resistant, when such rolls become worn the adhesive on the linerless web adheres more tenaciously to the worn roll and the linerless web has a tendency to follow the roll around. The web may bunch up or buckle between the platen roll and a stripper even though the stripper is immediately adjacent to or touches the platen roll. When the linerless web adheres to the platen roll there is also a tendency of the buckled linerless web to push against the stripper or to bow the stripper to make an easier throat between the platen roll and the stripper through which the linerless web can pass.
According to the invention, there is provided a support 18 with parallel support elements or members 19 which, as shown in
Initially, the support 18 is positioned so that the points 21 depress and dig into the outer surface 17′ of the platen roll 17 as illustrated in
The elements 19 are molded integrally with a bar portion 24 having ribs 25. The side of the bar portion 24 opposite the ribs 25 has spaced ribs 26. The bar portion 24 has three laterally spaced, oversize through-holes 27. The support or stripper 18 has a groove 28 disposed between the elements 19 and the ribs 25. A rigid metal bar generally indicated at 29 is received in the groove 28. The bar 29 is a composite comprised of a bar member 30 and a bar member 31 welded to the bar member 30. Internally threaded fasteners 32 pass through and are secured in aligned holes 33 and 34 in the bar members 30 and 31. Screws 35 pass through the holes 27 and are threaded into the threaded fasteners 32. The bar portion 24 and the composite bar 29 are clamped together by the head of the screw 35 and the fastener 32. Because of the clearances between the groove 28 and the bar 29 and between the holes 27 and the screws 35, the stripper 18 can be precisely positioned or adjusted manually so that the tip portions 20 penetrate or dig into the outer surface 17′ to the desired depth. While the one-piece molded stripper 18 is rigid, the bar 29 adds rigidity and thus helps to maintain the tip portions 20 positioned in the grooves 22. As shown, the bar 29 is mounted in frame plates 36 and 37 of the printer frame 38. End portion 39 of the bar 29 hooks into the frame plate 36, and end portion 40 snaps into a clip 41 screwed to the frame plate 37. Further aspects of the printer 13 are shown in U.S. Pat. No. 5,833,377 incorporated herein by reference. The frame plates 36 and 37 in the present application correspond to walls 126 and 127 in U.S. Pat. No. 5,833,377.
The platen roll 17 is preferably comprised of a metal shaft 42 on which an elastomeric sleeve 43 is secured. The shaft is 42 preferably driven as illustrated in U.S. Pat. No. 5,833,377 while the thermal print head 16 prints in the web 10. As the platen roll 17 rotates, the web 10 is stripped from the roll 17 by the stripper elements 19, and the printed, stripped web 10 passes over the elements 19 with the adhesive 14 in contact with upper edges 19′ of the elements 19. As shown in
The tip portions or cutters 20 cut the circumferential grooves by wearing away quite narrow circumferential zones of the outer portion of the sleeve 43 with relatively few rotations of the roll 17.
While the invention is applied to a platen roll 17 it is also useful when stripping adhesive-backed webs for various rolls other than platen rolls.
By way of example, not limitation, for a web which is about 102 mm wide, it is most preferred to use 14 stripper elements, however a greater or lesser number can be used. It is also within the spirit of the invention to have less than all the elements 19 extend into the grooves 22.
While the stripper 18 is stiffened or strengthened by the bar 29, the stripper 18 could be made stronger by making it from thicker plastics material and suitably mounting it to the frame plates 36 and 37. While the stripper 18 is preferably of one-piece molded plastics construction, the stripper 18 can be made in multiple parts.
The preferred illustrated shape of the tip portion 20 is such that if the platen roll 17 is to be rotated in the reverse direction from that shown by arrow A in
While the invention is particularly useful for use with linerless, tacky adhesive-backed, printable webs, the method and
While the invention is particularly useful for use with linerless, tacky adhesive-backed, printable webs, the method and apparatus of the invention can also be used with adhesive webs having siliconized release liners.
Other embodiments and modifications of the invention will suggest themselves to those skilled in the art, and all such of these as come within the spirit of this invention are included within its scope as best defined by the appended claims.
