WO1999026217A1

WO1999026217A1 - Stamp manufacture

Info

Publication number: WO1999026217A1
Application number: PCT/GB1998/003063
Authority: WO
Inventors: Richard J. Ashwell; Colin Gibson
Original assignee: The House Of Questa Ltd.
Priority date: 1997-11-15
Filing date: 1998-10-09
Publication date: 1999-05-27
Also published as: AU9546998A

Abstract

A method of stamp manufacture is disclosed wherein a web of stamp paper substrate is perforated by means of laser cutting. This enables extremely precise perforations to be provided around the periphery of a plurality of stamp images printed either before or after the perforation step. The substrate may additionally be provided with a pressure sensitive adhesive coating and applied to a release paper either before or after the perforation step which may additionally cut the stamp paper substrate around the periphery of individual stamps which are thus separable from one another, and in either case, fold lines may be produced in the release paper which coincide with an edge of a plurality of stamps so perforated such that a continuous web of a self-adhesive assembly may be produced. The fold lines in the release paper may also be produced by laser cutting so as to weaken the said release paper, or perforate same in a similar pattern to the perforations of the stamps such that resulting web may be fan-folded. Accordingly a fan-folded self-adhesive stamp assembly is also provided.

Description

Stamp Manufacture

This invention relates to the manufacture of stamps, labels, and other substrates of predefined size which are adapted to be adhered to. a carrier by a pressure sensitive adhesive layer on one side of the substrate. The invention relates in particular to the method of segregating individual stamps or labels on the web or sheet of substrate material from which they are constituted.

The invention also relates to self adhesive stamps assemblies. A self adhesive stamp assembly comprises the stamp material substrate on one side of which the stamps are printed and the other side of which is pressure sensitive adhesive, and a carrier sheet on a release surface of which the stamp substrate is held by the pressure sensitive adhesive.

Although the following description of the invention relates in the main to the manufacture of postage and revenue stamps, it will be readily understood that the invention can be applied with little or no modification to the manufacture of any adhesive labels of any desired shape, and that the description applies equally to such labels.

Current manufacture of stamps is effected by firstly printing one surface of a web or sheet of substrate material with a plurality of rows of the images which are displayed on the individual stamps. The substrate material is conventionally a pre-gummed paper with a dry but water-soluble adhesive compound applied to the alternate surface of the substrate from that which will receive the printing inks. It is important that the adhesive is dry so that the web of substrate material can be perforated without adhesion and subsequent forming of clumps of the chads produced by perforation within the perforating press. The perforation of the web is necessarily effected in precise register with the printed images on the web such that the image is exactly centrally located within the perimeter of the stamp defined by the perforations.

The water soluble adhesive layer has a number of disadvantages. Firstly, in moist and warm conditions, the adhesive layer may be activated resulting in the unwanted adhesion of the stamps, either to one another or to the inside of a booklet in which the stamps are contained, rendering the stamps useless. A second disadvantage is the inconvenience, and possible unpleasantness, to the user who has to moisten the adhesive, usually with saliva by licking the said adhesive layer, and has to affix a large number of stamps to envelopes and the like. Although the adhesive layer is non-toxic, such a user will rapidly be aware of the unpleasant taste in his mouth after application of only relatively few stamps in such manner.

Self-adhesive stamps have therefore been proposed, in which a pressure sensitive adhesive, such as a soluble acrylic adhesive, is applied to the opposite surface of the substrate to that which is printed with the stamp images as described above. The substrate is adhered to a silicone coated release paper to prevent any unwanted adhesion of the substrate, either to itself or to anything else. The main disadvantage associated with such pressure sensitive adhesives when applied ubiquitously to one surface of a substrate to be perforated is that the chads which are removed by perforation are liable to adhere to one another, thus clogging the perforating machine. Although die cutting of the substrate is currently effected and to a large extent overcomes this problem, perforation shapes are of importance on account of the security features that may be provided thereby. Also die cutting of stamps results in reduced customer acceptance, and such stamps are easily distinguishable from perforated stamps. Furthermore, the die cutting of substrates to which a pressure sensitive adhesive has been applied and which are mounted on a release paper, unless accurately adjusted, often results in unwanted cutting or embossing of the release paper. Thus a user may experience difficulties in removing an individual stamp from the release paper because said release paper has been cut along a portion of the edge of the stamp with an identical edge contour and the adhesion betwixt stamp and release paper precludes easy removal. Repeated fingering of this edge portion is generally required to separate the stamp from the release paper, which inconvenience somewhat defeats the objects of simplicity and convenience to which the provision of self-adhesive stamps is directed.

One method of the manufacture of self-adhesive stamps is given in European Patent application No. 0753187 to Harrison & Sons Ltd. This document relates to the application of a pattern of pressure sensitive adhesive in which there is little or no pressure sensitive adhesive adjacent the perforated edges of every stamp on the web of substrate material. Thus in the region of the perforations, there is no adhesive and the chads do not adhere to one another. The substrate material is mounted on a release paper and a self adhesive stamp with the desired aesthetic appearance and security features, i.e. difficulty of forgery, provided by perforation results. The major disadvantage with such method is the requirement to apply a pattern of pressure sensitive adhesive as opposed to ubiquitous application thereof. Firstly, the pattern must be in precise register with the lines of perforations (if the substrate is perforated prior to adhesive application), but in any event there must be no application of adhesive to an area of substrate which will be perforated. The viscous and unmanageable nature of the adhesive, which is usually applied at elevated temperatures makes this a difficult proposition. Secondly, the absence of adhesive around the periphery of the stamp is such that when the stamp is applied to a carrier, such as an envelope or the like, the perforated edges of the stamp are not adhered to the carrier. Said edges are thus likely to become frayed and ragged as the carrier material is handled through sorting offices and mail bags, and thus be separated from the surface of the carrier. Such separation in turn increases the possibility of dirt ingress underneath the stamp, especially if the perforated edges are separated from the carrier to such an extent that the adhesive layer is exposed. Under certain conditions, the is a possibility that an impediment could be trapped underneath one of the edges of the stamp which could tear the stamp or the carrier if there were any significant relative movement between the carrier and the impediment.

In extreme circumstances there is a likelihood that the stamp may be completely removed from the carrier, with obvious disadvantages.

It is an object of this invention to provide a method of providing a self-adhesive stamp or label which can be conveniently applied to a carrier such as an envelope or the like without the abovementioned subsequent disadvantages.

It is a further object of this invention to enhance the security features currently available by creating a perforated shape around the stamps.

It is a yet further object of this invention to provide a self-adhesive stamp, label or the like of any desired shape, the edges of which are of any desired contour and have adhesive adjacent said edges around the entire periphery of the said stamp or label facilitating secure adhesion to a carrier, such as an envelope or the like. It is a still further object of this invention to provide a stamp production method whereby self-adhesive stamps are provided as a web of continuous stationery.

According to the present invention there is provided a method of cutting a web or sheet of a substrate, one surface of which is adapted to be printed with a number of identical images in rows or otherwise arranged, a layer of adhesive being applied to the alternate surface to which a release paper is affixed, characterised in that a laser light traces a path on the substrate eliminating matter thereof to define a number of discrete portions of the substrate corresponding to the number of images printed or to be printed thereon, said portions being substantially unattached to the web of substrate and to one another.

By "substantially unattached" is meant that there is practically no tearing required between said portions and the remaining substrate material or adjacent portions as a particular portion is removed from the release paper to which it is affixed by the adhesive.

Furthermore, it is to be appreciated that printing of the substrate may be effected either before or after the material of the substrate has been eliminated. In either case it is preferable that the elimination path, to which the said path will hereinafter be referred, is in precise register with the images printed or to be printed on the substrate such that the resulting removable portions are identical.

It is further preferable that the intensity of the laser light is such that only the substrate material is eliminated, the release paper being substantially unaffected by the laser light.

Preferably, the intensity of the laser light may be adjusted as required by the thickness of the substrate and adhesive layer, and thus the depth of penetration of the laser light through the substrate can be adjusted.

In all embodiments of the invention, it is preferable that the discrete portions formed by the elimination of the substrate material are stamps of value, such as postage stamps, revenue stamps or labels and the like.

It is further preferable that the elimination path of the laser light along any particular edge of the stamp defined thereby is such that said edge appears to match conventionally perforated shapes.

It is yet further preferable that the laser light eliminates areas of predefined shapes of the substrate between and surrounding the stamps, said areas being connected by a linear elimination path, thus providing the stamps of the substrate material with a perforated effect without the production of chads.

It is preferable that the adhesive is a pressure sensitive adhesive.

In one aspect of the invention, it may be preferable that after the laser light has traced the elimination path, the remaining carcase of substrate material is removed from the release paper leaving the discrete portions of substrate material thereon.

According to a second aspect of the invention, there is provided a self-adhesive stamp assembly comprising a release paper and a stamp substrate releasably attached by adhesive to said release paper, characterised in that said assembly is provided as continuous stationery and in fan folded form, each section of the assembly between folds forming a sheet or page of stamps. This has the advantage that the assembly can be held in fan folded form at the point of sale and to dispense the stamps, the retailer simply tears off the required number of stamps or sheets needed by a consumer.

Present methods of dispensing gum backed stamps do not lend themselves to this form of dispensing, in that they are formed into booklets, or in large sheets. The formation of the stamps in booklets means an extra manufacturing process, whilst the storing of large sheets means the taking up of more space than is justified.

The fold lines are preferably formed as lines of weakness to ensure that the assembly can be torn along said lines easily.

The said fold lines are preferably defined by a laser which eliminates the material of the release paper, and further preferably this is effected through the stamp substrate which is adhered to said release paper.

The fold lines in the stamp assemblies of the second aspect of the invention may also be defined by a conventionally used cutting method known as "rouletting" in which weakening cuts are formed in only the release paper.

The perforations in the case of the fold lines may furthermore pass through both the stamp material substrate, and the release paper.

It is therefore possible either to provide fold lines in the release paper prior to its coming into contact with the stamp substrate, in which case the release paper provided with fold lines and the stamp substrate on which individual images may have been printed are required to be in precise register to ensure that the fold lines coincide with the edge of a row of stamps on the stamp substrate, or alternatively to provide the fold lines i the release paper with the stamp substrate adhered thereto as described above.

The release paper and stamp substrate are preferably in web form defining a longitudinal axis, the fold lines extending transverse to the longitudinal axis, but fold lines may also extend in a direction which is parallel to the longitudinal axis depending on the particular direction of substrate and/or release paper elimination or rouletting.

The elimination of the material of the substrate and/or release paper using laser light as according to the invention is an improved method of cutting same, and provides much greater flexibility and control.

There is particular advantage in using laser light to cut the stamps from the substrate in that alteration of the elimination pattern is simply effected, possibly under the control of a computer program. Previously, modification of the perforating die was precluded on the grounds of expense and tooling difficulties. Also, the capabilities of present laser equipment enables precision requirements to be easily met.

Additionally, the elimination of the substrate material by laser is a non-contact process, and thus reducing both the likelihood of any imperfections in the resulting stamps produced by such method and machinery down time previously caused by the fouling of the perforating or punching machinery or damage to the perforating or punching tool.

A specific embodiment of the different aspects of the inventions is now provided by way of example only with reference to the accompanying drawings, wherein: Figure 1 shows a perspective view of press machinery adapted for use with the invention;

Figure 2 shows a plan view of a portion of a web of stamp paper with individual stamps defined by edges resulting from the elimination of stamp paper by laser, and

Figure 3 shows a perspective view of the web of Figure 2 curved to facilitate removal of the stamp therefrom.

Fig. 4 is a plan view of a stamp assembly embodying the second aspect of the invention;

Fig 4A is a plan view of a stamp assembly embodying the second aspect of the invention, but with the stamp material substrate adopting an alternate orientation to that shown in Figure 4;

Fig. 5 is a side view of the assembly of Fig. 4 when in fan folded form;

Fig. 6 is a perspective view showing one method according to the second aspect of the invention; and

Fig. 7 is a side view showing another method according to the second aspect of the present invention.

Referring firstly to Figure 1, a web of stamp paper 2 has an upper surface 4 and a lower surface 6. The stamp paper 2 is specifically adapted for the printing of postage stamps, in that it may contain luminescent compounds of have such compounds printed thereon to enable automatic mail sorting machines to recognise and authenticate postage stamps printed on such paper. The stamp paper 2 passes between a blanket cylinder 8 and an impression cylinder 10, the blanket cylinder applying to the upper surface 4 of the stamp paper 2 a plurality of stamp images 12. The ink is transferred to the blanket cylinder 8 by a means of a plate cylinder (not shown) as is usual practise in lithographic printing, but it will be appreciated by the skilled reader that the particular method of printing is unimportant. Furthermore, only a single row of images 12 is shown in the figure for the purposes of clarity.

The stamp paper with images 12 printed thereon is then passed between a pair of cylinders 14, 16, cylinder 16 being an adhesive application cylinder which applies adhesive to the lower surface 6 of the stamp paper 2. Such layer is indicated by the hatching 18 shown in the figure. The adhesive applied to the surface 6 of the stamp paper is preferably a hot-melt adhesive, or any of the commonly available pressure sensitive adhesives which may be applied in the manner described above, or in any other manner so proposed in which there is uniform application of an adhesive to the lower surface 6 of the stamp paper across the entire width of the web.

The stamp paper 2 is mounted on a release paper 20, which has a silicone coated upper surface 22 and a lower surface 24, by compression between a pair of pressure cylinders 26, 28. The resulting combined laminated web 30 of stamp paper and release paper then passes beneath laser apparatus 32 powered and controlled through a connection cable 34. A beam of laser light emanates from the lower portion of the laser apparatus 32 as schematically shown at 36. The intensity of this beam is precisely controlled so as to burn, evaporate or otherwise eliminate the stamp paper surrounding the images 12 in a uniform and repeatable manner. It is to be understood that the use of the word "burn" and cognate expressions as used hereinafter is intended to encompass all such means of eliminating matter and others not specifically mentioned.

The depth of burn is controlled such that the release paper 20 is substantially unaffected. Such burning is effected by controlling the laser apparatus, possibly by computer, to trace a predetermined burn path or pattern around each individual image within the row of images 12. Where the laser apparatus 32 is computer controlled, the laser beam may trace out any desired burn path on the stamp paper 2 and with high precision, depending on the collimation of the laser light. An example of such a burn path which has been designed to give the effect of perforations is shown in Figure 2.

In Figure 1, the images 12 are applied to the upper surface 4 of the stamp paper with a degree of separation which requires that separate burn paths are required between each of the images to create a stamp 42, whereas in Figure 2, the proximity of the printed images 12', 12" is such that only a single burn path is required to be traced by the laser beam between the said images to create individual stamps 42.

As an optional additional step to the process shown in Figure 1, the stamp paper 2 may be separated from the combined laminate 30 and passed over a separation cylinder 34 after the burn process has been effected, beneath which the release paper 20 passes. The burning of the stamp paper 20 allows said stamp paper to be separated from the release paper as a carcase 38 in which apertures 40 exist as a result of the burning of said stamp paper around the images 12. Each edge of the apertures 40 represents a burn path of the laser beam on the stamp paper, and thus it can be observed from the figure that separate and distinct burn paths are required between each of the images 12 as described above. If the burn path traced by the laser beam 36 was as shown in Figure 2, only a single aperture 40 would exist in the carcase 38 for each block of stamps, and the edges of adjacent stamps, although separate as a result of the incision, would be contiguous as shown in Figures 2 and 3.

Individual stamps 42 remain on the release paper after the separation of the carcase 38 therefrom, and the bond strength of the adhesive 18 between the lower surface 6 of the stamp paper 2 and the upper surface 22 of the release paper 20 is such as to permit easy removal of the stamps 42 therefrom.

The uniform application of the adhesive across the entire width of the web of stamp paper 2 on its underside 6 is advantageous in that after burning of the stamp paper has been effected by the laser beam 36, said adhesive completely covers the underside of the stamps 42, regardless of the burn path which is traced therearound by the laser beam 36. Thus stamps manufactured according to the invention may be securely attached to a carrier, such as an envelope, not only in their centre but around their entire periphery which may be accordingly patterned as desired. This represents an improvement over the prior art methods of stamp application, in which either a moistenable adhesive layer was licked by a user but usually not completely, or in which there was substantially no adhesive adjacent the periphery of the stamp, as disclosed in the abovementioned European patent application.

Figure 3 shows the simplicity of removal of a stamp 42 effected according to the invention, but in the figure the carcase 38 has not been separated from the release paper 20 as may optionally be effected as shown in Figure 1. Figure 3 shows a thumb and forefinger 44, 46 respectively of a user which acts on the combined laminate 30 to bend said laminate. This bending action, and the bond strength between the adhesive on the underside of the stamp 42 and the upper surface 22 of the release paper 20 is such that an edge 48 of the stamp 42 separates from the release paper 20, thus presenting an area in the region of said lower edge 48 which may be pinched by the fingers on the other hand of the user to remove the stamp 42.

Referring now to figure 4, a web assembly 10X is shown, and comprises a carrier sheet 12X having an upper surface 14X having a release characteristic, for example by having a silicone coating thereon, and on the surface 14X is adhered a substrate of printed stamps 16X. On the rear of the stamps 16X is pressure sensitive adhesive by which the substrate adheres to the carrier.

The stamps are surrounded by lines 22X of perforations formed as set forth in said co-pending application or as described subsequently herein.

The assembly is arranged so that there are defined sheets in the assembly, these sheets being defined between fold lines C-C, A-A and B-B. The fold lines are formed by cutting perforations as described in said co-pending application, or as set forth hereinafter, or by rouletting, or by any other means, and the assembly is fan folded as shown in Fig. 5 to place it in condition for transportation and for convenience in dispensing by retailers. It is in fact preferred that the perforations of the fold lines pass through both the substrate and the carrier sheet so that the fold line is visible from both sides of the strip.

Figure 4A shows a similar self-adhesive stamp assembly to that shown in Figure 4 and like reference numerals have been used to indicate like parts, except that the carrier web 12X is wide enough to accommodate transversally disposed printed stamp material substrate portions 16X. Fold lines A-A, B-B, C-C, and D-D may be provided as described above in relation to Figure 4. The direction of travel of the self-adhesive stamp assembly is shown by arrow 15X in both Figures 4 and 4A.

The length of fan folded sheets can be varied to suit individual requirements.

Fig. 6 shows how the method according to the invention in the said co-pending application can be modified in accordance with one example of the second aspect of this invention. In this Figure, the substrate, before printing is shown at 30X, and it travels in the direction of the arrow 32X. As it moves, it is printed with the stamp information at 34X, and at 36X laser cutting of the substrate is effected to define lines of perforations 38X between individual stamps.

The printed and perforated substrate is then laminated to the carrier sheet 40X at laminating station 42X.

In a modification, the perforations can be provided before the printing step.

In the arrangement of Fig. 7, the substrate 50X (already printed) and the carrier 52X are delivered to the cutting apparatus 54X in laminated form. They are separated at 56X, and whilst they are so separated, the substrate 50X is provided with the perforations at 58X, and then the substrate 50X and the carrier 52X are recombined at 60X. A collecting tray 62X may be provided under the cutting means to prevent cuttings from web 50X from falling onto the web 52X. In a modification, the printing could be effected after step 60X, or between step 58X and 60X.

The apparatus of Fig. 6 or 7 could be used also to form the fold line perforations. The advantage of forming the perforations whilst the substrate is separated from the carrier is that there is no need to exercise the control needed when the cutting whilst the substrate is laminated to the carrier.

Claims

CLAIMS:

1. A method of cutting a web or sheet of a substrate, one surface of which is adapted to be printed with a number of identical images in rows or otherwise arranged, a layer of adhesive being applied to the alternate surface to which a release paper is affixed, characterised in that a laser light traces a path on the substrate eliminating matter thereof to define a number of discrete portions of the substrate corresponding to the number of images printed or to be printed thereon, said portions being substantially unattached to the web of substrate and to one another.

2. A method according to claim 1 characterised in that that the intensity of the laser light is such that only the substrate material is eliminated, the release paper being substantially unaffected by the laser light.

3. A method according to claim 1 or 2 characterised in that the intensity of the laser light may be adjusted as required by the thickness of the substrate and adhesive layer, and thus penetration of the laser light can be adjusted.

4. A method according to any of the preceding claims characterised in that the discrete portions formed by the elimination of the substrate material are stamps of value.

5. A method according to any of the preceding claims characterised in that the elimination path of the laser light along any particular edge of the stamp defined thereby is such that said edge appears to match conventionally perforated shapes.

6. A method according to any of the preceding claims characterised in that the laser light eliminates areas of predefined shapes of the substrate between and surrounding the stamps, said areas being connected by a substantially linear elimination path so that chads are not produced.

7. A method according to any of the preceding claims characterised in that the adhesive is a pressure sensitive adhesive.

8. A method according to any of the preceding claims characterised in that the carcase of substrate material is removed from the release paper after the laser light traces an elimination path on the substrate leaving the discrete portions of substrate material thereon.

9. A self-adhesive stamp assembly comprising a release paper and a stamp substrate releasably attached by adhesive to said release paper, characterised in that said assembly is provided as continuous stationery and in fan folded form, each section of the assembly between folds forming a sheet or page of stamps.

10. A self-adhesive stamp assembly according to claim 9 characterised in that the fold lines are formed as lines of weakness to ensure that the assembly can be torn along said lines easily.

11. A self-adhesive stamp assembly according to either claim 9 or claim 10 characterised in that the said fold lines are defined by laser elimination of the material of the release paper.

12. A self-adhesive stamp assembly according to claim 11 characterised in that the laser elimination of the material of the release paper is effected through the stamp substrate which is adhered to said release paper.

13. A self-adhesive stamp assembly according to claims 9 or 10 characterised in that the fold lines in the release paper are defined by rouletting.

14. A self-adhesive stamp assembly according to claims 10, 11, or 12 characterised in that the fold lines comprise perforations.

15. A self-adhesive stamp assembly according to any of claims 9- 14 characterised in that the release paper and stamp substrate are in web form and define a longitudinal axis, and in that at least one fold line extends transverse to the longitudinal axis.

16. A self-adhesive stamp assembly according to any of claims 9- 14 characterised in that the release paper and stamp substrate are in web form and define a longitudinal axis, and in that at least one fold line extends in a direction which is parallel to the longitudinal axis depending on the particular direction of cutting.