STAMPS

Abstract: An improved stamp is disclosed which has the appearance of a conventional perforated edge stamp. The stamp has simulated edge perforations (1) produced by cutting a series of concave portions (5) and series of convex portions (7). The concave portions (5) smoothly terminate with the concave portions (7). The stamps can be produced on an elongate web (3) and be carried on a backing web (17) by a peel and stick adhesive (9). By cutting the simulated perforations (1) with the smoothly terminating concave, convex portions (5, 7) it is possible to strip unwanted skeleton material on which the stamp is printed from the backing web (17), thereby leaving the stamps in spaced apart separate relation on the backing web (17) for subsequent individual peeling therefrom. A method for producing the stamps and a cutting die for cutting the stamps is also disclosed.

Description: STAMPS FIELD OF THE INVENTION This invention relates to stamps and relates particularly but not exclusively to an improved stamp and method of manufacture and cutting die therefor. DESCRIPTION OF THE PRIOR ART Hitherto stamps have been produced in large sheets and have been separable individually from the large sheets by providing perforations around each stamp. A user tears the stamp from the sheet by tearing across the perforations. It has been proposed to provide stamps with a self sticking adhesive medium so that stamps can be dispensed from a backing sheet in a manner similar to that for peel and stick labels such as those dispensed from a roll. Stamps if dispensed from a roll should be placed individually in spaced apart relation onto a carrier backing so they can be dispensed in a manner similar to that for normal peel and stick labels dispensed from a roll. Stamps of this type should therefore have the appearance of a conventional stamp with perforations around the perimeter. Normal stamps have corners or sharp edges across the perforations and thus it is generally impossible to provide for easy separation of stamps from a paper web on which they are printed so they can be applied in spaced apart relationship on a backing or carrier web for peel and stick stamp dispensing such as from a roll. OBJECT AND STATEMENT OF INVENTION The present invention attempts to overcome the aforementioned problems. Therefore in accordance with a first broad aspect of the present invention there may be provided an improved postage stamp comprising a web of material upon which is printed the stamp image, said stamp having a peripheral edge shape which simulates a peripheral edge shape of a perforated stamp, the peripheral edge shape having concave portions smoothly terminating with convex portions. Most preferably the stamp is applied to a backing web of material and held thereto by a peel and stick adhesive carried by the undersurface of said stamp whereby, in use, the stamp and the peel and stick adhesive can be peeled integrally from the backing web for subsequent application to a postal article. Preferably the paper on which the stamp is printed has a detection/clay coating which is calendered to provide for adhesion of an acrylic based UV cured letter press ink. Preferably the backing web is an elongate web and a plurality of such stamps are applied to said backing web at spaced apart seperate intervals along the length thereof . Preferably, said peel and stick adhesive is water soluble removable whereby to permit said stamp to be removed from a postal article, if required, by the application of water. Preferably, said peel and stick adhesive is carried on an independent layer of water soluble material applied directly to the undersurface of said stamp. According to another aspect there is provided a method of producing stamps for peel and stick use, comprising printing a stamp image on a web of material carried on a backing web of material by a peel and stick adhesive, cutting a simulated perforated edge shape around said stamp image, the perforated edge shape having concave portions smoothly terminating with convex portions . According to another aspect there is provided a cutting die for cutting stamps to have an edge perforation appearance simulating that of a conventional stamp, said cutting die comprising a continuous cutting surface defining the edges of a stamp, said cutting surface having a series of concave portions and series of convex portions, the concave portions smoothly terminating with the convex portions . According to another aspect there is provided a cutting die for producing stamps spaced apart sequentially along the length of a backing web said die being a cylindrical roller having upstanding cutting surface means shaped to conform to the desired peripheral shape of a stamp with perforations, the perforations being simulated by concave cutting portions and convex cutting portions, the convex cutting portions smoothly terminating with the concave cutting portions and being around the circumference of said roller whereby when the roller is placed in cooperation with a platten, the stamps can be cut by the cutting surfaces as the cutting roller is rotated and a web of paper on which stamps are printed passes therebetween. Most preferably the cutting surfaces are such that a plurality of independent cutting surfaces are provided around the circumference of said cutting die whereby a plurality of stamps will be cut during a single rotation of said cutting die. BRIEF DESCRIPTION OF THE DRAWINGS In order that the invention can be more clearly ascertained examples of preferred embodiments will now be described with reference to the accompanying drawings wherein:- Figure 1 is a front view of a stamp made in accordance with an example of the present invention. The stamp is shown considerably enlarged; Figure 2 is an enlarged view showing the detail of simulated edge perforations taken along part "A" of figure 1; Figure 3 is a side view of the stamp showing an enlarged detail of part "A" in figure 1; Figure 4 is a schematic side view of apparatus and process in an example of the present invention. Figure 5 is a plan view of an elongate backing sheet containing stamps placed in four rows across the sheet in spaced apart relationship and consecutively in spaced apart relationship along the sheet. Figure 6 is a perspective view of a rotary cutting die for cutting stamps from a web of stamp materials so that they will be in spaced apart relationship on the backing web. Figure 7 is an elevation view of the cutting die mating with an anvil showing the backing web therebetween. Figure 8 is a sectional view along line 8,8 of Figure 6 showing the transverse cross-section of part of the cutting die which cuts the stamps from the web of stamp material. Figure 9 is a view similar to that shown in Figure 3 but of a different embodiment where there is an independent water soluble layer and an independent tack adhesive layer. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to figure 1 there is shown a front view of a stamp. The stamp image has not been shown in order to aid clarity. The stamp image is produced by a known printing process which printing itself does not form any part of the inventive subject matter herein. The stamp may be produced in any convenient size and shape. The stamp has the appearance of a conventional stamp. This is because it has simulated perforations 1 around the perimeter of a web 3 of material on which the stamp image is printed. Typically, the web of material 3 comprises conventional stamp paper. A particularly preferred paper is known as Jac-ps stamp paper manufactured by Jac Paper Australia Pty. Ltd. of Cnr. Indwe and Cala Streets, Tottenham, Victoria, 3012, Australia. The paper is detection coated (UV luminescent) semi-gloss white paper. Other suitable web materials may be used. The simulated perforations 1 are produced by having a series of concave portions 5 and interconnected convex portions 7. Preferably the diameter of the concave arcs is 1.25 mm and the diameter of the convex arcs is 0.6 mm. Thus, it can be seen by figure 2 there is a smooth transition and smooth termination between the concave portions 5 and the convex portions 7. Referring now to figure 3 where there is shown an enlarged side view of part of the stamp it can be seen there is the web 3 upon which the printing is applied and then a water soluble tack adhesive 9 applied on the under surface of web 3. Preferably the water soluble tack adhesive 9 is known as a permanent "wash away" adhesive to be sold under trade designation WLKl by Jac Paper Australia Pty. Ltd. and has been developed especially for us for this purpose. This adhesive has the following properties:- PERMANENT "WASH AWAY" ADHESIVE WLKl is a permanent synthetic pressure adhesive with excellent UV resistance and ageing properties. It combines high initial tack and specific adhesion to cellulose with easy deactivation by submersing in warm water. ADHESIVE SPECIFICATIONS: Adhesion FTM1 >10.0 N/2.5cm Initial Tack (loop tack) FTM9 >8.0 N/625mm 2 Cohesion (lkg/5cm 2 ) >15 minutes Application Temperature >0°C Temperature Resistance Minimum Temperature -30° C Maximum Temperature (Applied to Substrate 1 hour) 110° C Tack Time (as per Australia Post Specification 138) fibre tear within 5 sees Initial Grab (as per Australia Post Specification 138) : Pass Removability: Label may be removed from substrate without damaging print carrier after 10 minutes submersion in warm water. Referring now to figure 4 there is shown apparatus and a production process for producing the stamps . A typical apparatus for this purpose is a rotary Label Press model 250 made by KO-PACK Corp., 2-11 Kanda-Tacho, Chiyoda-ku, Tokyo, Japan. A web material 3 is taken off a roll 11 and fed to a printer 13 where the stamps are printed sequentially and in spaced apart relation onto web 3. The web 3 is carried adhered to a backing web 17 by the water soluble tack adhesive 9. Typically the backing web 17 may comprise a siliconized glassinated paper. A typical glassinated paper web 17 comprises trade designation KV75 from Jac Paper Australia Pty. Ltd. Because web 3 is provided with the water soluble tack adhesive 9 on the undersurface, web 3 adheres to web 17. Typically, four stamps are produced simultaneously across the web 3 but any desired number can be printed depending on the width of the paper and the capabilities of the label press. As the web 3 passes from the printer 13 it passes under drying means (not shown) which may comprise known infra-red drying means . The two webs 3 and 17 then pass to a pressing station 21 which comprises a rotating drum platen 23 and a rotating die head 25 in the form of a cutter. The die -head 25 is shaped to cut the required perimeter or peripheral shape of the stamp. The die head 25 and platen 23 are adjusted so that when the die head 25 engages with the web 3 it cuts web 3 without cutting web 17. The die head 25 will be described in detail in due course. As the webs 3 and 17 pass from the pressing station 21 the unwanted waste material around the stamps is stripped therefrom and wound onto roll 27. Stamps 29 then remain on web 17 and are subsequently rolled onto roll 31. The roll 31 can then be removed arid then cut into required strips - one stamp wide - and into lengths of stamps and rolled and placed into suitable dispensing containers of known type. Thus, the stamp can be peeled from the backing 17 in a manner similar to that of known peel and stick labels . Because four stamps are produced simultaneously across web 3 the stamps may, if desired, be slit into four strips so that each strip is provided to be placed a respective dispensing container. Because of the particular shape of the simulated perforations 1 around the perimeter of the stamps, the waste material strips easily from web 17 without removal of the stamps 29. This occurs because of the smooth terminations or transitions between the convex portions 7 and the concave portions 5 thus making a completely continuous non pointed severance of the stamps from the web 3. The stamps can be removed from postal articles by soaking in warm water for about 10 minutes . Referring now to figure 5 there is shown how the stamps 29 are produced in four rows extending along the length of the backing 17. The four rows are shown as row A, row B, row C, row D. Referring now to figure 6 there is shown a perspective view of the die head 25. Here it can be seen that it is an elongate cylinder which comprises a reduced diameter central portion 33 with bearing surfaces 35 at each end. Centrally of the reduced diameter portion 33 there is provided a series of circumferentially extending cutting surfaces 37 in four rows A, B, C, D. The cutting surfaces 37 are spaced around the circumference and each cutting surface 37 is of the same peripheral outline as that of each stamp to be cut from the web 3. It can be seen that the cutting surfaces 37 extend upwardly from the reduced diameter portion 33 and define, in this case - rectangular shaped cutting surfaces to cut rectangular shaped stamps . Figure 7 shows how the die head 25 cooperates with the cylindrical platen 23. In each case, the die head 25 and the platen 23 are driven in unison so there will be smooth passing of webs 17 and 3 therebetween. The die head 25 is brought into firm engagement with the platen 23 by the bearing surfaces 35 engaging with the surfaces of the platen 23. The web of backing 17 with the stamp paper 3 thereon is fed between the die head 25 and the platen 23. The distance of spacing of the radially outermost surfaces of the cutting surfaces 37 is such that when the webs 17 and 3 pass between the die head 35 and the platen 23 the cutting surfaces 37 will sever the web 3 but not the backing web 17. Thus, the stamps are cut by a rolling action with the cutting surfaces 37 as the webs 3 and 17 pass between the die head 25 and the platen 23. The stamps will be individually spaced apart longitudinally along the length of the backing web 17. Thus, the remaining material around the cut portion of the stamps can be stripped therefrom as a skeleton and wound onto a roll 27 shown in figure 4. Figure 8 shows a transverse cross-section through one of the cutting surfaces 37 taken along section line 8-8 shown in figure 6. Here it can be seen that the included angle of the cutting surfaces 37 is 40 degrees. Other angles may be used if desired. It has been found that an angle of substantially 40 degrees provides for the required cutting of the web 3 over web 17. It can be seen that the cutting surfaces 37 have a radially outermost pointed cutting surface 39. Referring now to Fig. 9 there is shown an alternative embodiment where there is shown an enlarged view of part of the stamp. It can be seen that there is a web 3 upon which the printing is applied. The web 3 may have a detection/clay coating on the upper surface. The detection coating may consist of phosphorescent, luminescent or fluorescent pigment. The coating is finished by means of calendering to give the following physical properties. Smoothness: ^900 Sees (Bekk Smoothness) Porosity : 600 secs/lOOcm 3 (Bekk Porosity) Dennison wax pick strength: >6 The reverse or underside of web 3 is coated with a water soluble gum layer 41. That layer 41 is coated with a pressure sensitive tack independent adhesive (PSA) layer which may be removed from the printed stamp by solvation or dispersion of said gum layer 41 when submersed in warm water for a period of 10 minutes. The water soluble gum layer 41 is typically a low viscosity, partially hydrolysed polyvinyl alcohol (Brookfield Viscosity {4% aqueous solution at 20°C} : <20 mPa.s ) (Hydrolysis : <98 mole %). The polyvinyl alcohol (PVOH) concentration w/w may be in the range 1 to 25%. The water soluble layer 41 may also include polyvinyl acetate dispersions, alkyl acrylate esters, ethylene or alkyl maleate or copolymers thereof in the range 1 to 60% non volatile w/w. The water soluble layer 41 may also consist of starches, modified starches or starch derivatives, cellulosic materials such as hydroxyethyl, carboxymethyl or methyl cellulose of similar, plant derivative gums such as gum arable , gum tragacanth, carigeenan or similar or combinations of the above. The pressure sensitive tack adhesive (PSA) layer 43 may be based upon a high tack aqueous dispersion or solution of acrylic acid esters that may include 2 ethyl hexyl, methyl, ethyl or n-butyl acrylates or copolymers thereof in the range of 15-50% non volatile. The PSA may also be based upon ethylene vinyl acetate (EVA) copolymers, solutions or aqueous dispersions thereof or terpolymers of EVA and the abovementioned acrylic acid esters in the range 5-50% w/w non volatile. The PSA base may also include natural or styrene-butadiene rubbers, aqueous dispersions or solutions thereof in the range 10-50% w/w non volatile. The PSA should also include "tackifying" resins in the range 5-40% w/w non volatile. The resinous "tackifiers" may be solutions or dispersions of gum rosin, rosin esters or rosin derivatives, petroleum hydrocarbon, poly alpha or beta pinene resins or similar. To complete the adhesive small quantities (<5% w/w) of machinability/coating adjuncts may be incorporated such as (i) Surfactants - to aid in wetting and reduction in foam generation (ii) antioxidants (iii) colourants - dyes and pigments (iv) polyalkyl siloxanes - to aid in clean diecutting (v) finely dispersed silicas - to reduce adhesive bleed. ADHESIVE FORMULATION Ingredient Quantity 1. 2 ethyl hexyl acrylate dispersion (55% non volatile) 36 parts 2. Rosin ester dispersion 56.5 " 3. Iso-octanol Q.V. 4. Water . 7.5 100 parts Viscosity (Brookfield) : 150 - 250 mP .S at 20° C (spindle 1 speed: 20 r.p. . ) 24 hr peel adhesion to glass FTM 1 > 10 N/2.5cm Initial tack (loop tack) FTM 9 > 8 N/625mm 2 Application Temperature > 0 U C, Temperature Resistance minimum : -30°C maximum (applied to glass for lhr) : 110°C Tack time (as per Aust.Post specification 138) : fibre tear within 3 sees. Modifications may be made to the invention as would be apparent to persons skilled in the art of producing peel and stick labels and/or stamps. These and other modifications may be made without departing from the ambit of the invention, the nature of which is to be determined from the foregoing description.

Claims: CLAIMS 1. An improved postage stamp comprising a web of material upon which is printed the stamp image, said stamp having a peripheral edge shape which simulates a peripheral edge shape of a perforated stamp, the peripheral edge shape having concave portions smoothly terminating with convex portions. 2. A stamp as claimed in claim 1 applied to a backing web of material and held thereto by a peel and stick adhesive carried by the undersurface of said stamp whereby, in use, the stamp and the peel and stick adhesive can be peeled integrally from the backing web for subsequent application to a postal article. 3. A stamp as claimed in claim 2 wherein said web of material upon which is printed the stamp image has a detection/ clay coating which is calendered to provide for adhesion of an acrylic based UV cured letter press ink. 4. A stamp as claimed in claim 3 wherein said coating also permits adhesion of a cancelling ink for stamps such as a high linseed oil content cancelling ink. 5. A stamp as claimed in claim 2 wherein said backing web is an elongate web and wherein there are a plurality of such stamps applied to said backing web at spaced apart seperate intervals along the length thereof . 6. A stamp as claimed in claim 5 wherein said peel and stick adhesive is a tack adhesive. 7. A stamp as claimed in claim 5 wherein said peel and stick adhesive is water soluble removable whereby to permit said stamp to be removed from a postal article, if required, by the application of water. 8. A stamp as claimed in claim 7 wherein said peel and stick adhesive is carried on an independent layer of water soluble material applied directly to the undersurface of said stamp. 9. A method of producing stamps for peel and stick use, comprising printing a stamp image on a web of material carried on a backing web of material by a peel and stick adhesive, cutting a simulated perforated edge shape around said stamp image, the perforated edge shape having concave portions smoothly terminating with convex portions . 10. A method as claimed in claim 9 including stripping waste skeleton material of the web of material on which the stamp image is printed from said backing web of material, so said stamp remains on said backing web of material for subsequent peeling therefrom. 11. A method as claimed in claim 9 wherein both said web of material on which the stamp image is printed and said backing web are elongate and a plurality of stamp images are printed and cut along the length thereof . 12. A method as claimed in claim 11 wherein said stamp images are in spaced apart relation along the length thereof and the cutting of each stamp is seperate from the cutting of adjacent stamps. 13. A method as claimed in claim 12 including stripping waste skeleton material of the web of material on which the stamp images are printed from said backing web of material, so the stamps remain on said backing web in seperate spaced apart relation for subsequent peeling therefrom. 14. A method as claimed in claim 11 wherein the printing of the stamp images is perforated by a rotary label press . 15. A method as claimed in claim 14 where the cutting is perforated by a rotary cutter provided with a plurality of circumferentially spaced apart stamp cutting surfaces, each stamp cutting surface having a shape to cut simulated perforations by having a series of convex shaped portions and concave shaped portions, the convex portions smoothly terminating with the concave portions . 16. A cutting die for producing stamps spaced apart sequentially along the length of a backing web said die being a cylindrical roller having upstanding cutting surface means shaped to conform to the desired peripheral shape of a stamp with perforations, the perforations being simulated by concave cutting portions and convex cutting portions, the convex cutting portions smoothly terminating with the concave cutting portions and being around the circumference of said roller whereby when the roller is placed in cooperation with a platten, the stamps can be cut by the cutting surfaces as the cutting roller is rotated and a web of paper on which stamps are printed passes therebetween. 17. A cutting die for producing stamps wherein the cutting surfaces are such that a plurality of independent cutting surfaces are provided around the circumference of said cutting die whereby a plurality of stamps will be cut during a single rotation of said cutting die. 18. A cutting die for cutting stamps to have an edge perforation appearance simulating that of a conventional stamp, said cutting die comprising a continuous cutting surface defining the edges of a stamp, said cutting surface having a series of concave portions and series of convex portions, the concave portions smoothly terminating with the convex portions .

Inventors: AVERY KERRY, GRAY ROBERT, POWER JOHN RODNEY, SMITH H, AVERY, KERRY, GRAY, ROBERT, POWER, JOHN, RODNEY, SMITH, H.
Applicants: AUSTRALIAN POSTAL CORP, AUSTRALIAN POSTAL CORPORATION TRADING AS AUSTRALIA
Application year: 1991
Main classification: B26F1
IPC codes: B26D7, B26F1, B26F3, B44F1, G09F3