CA2186759A1

CA2186759A1 - Self-adhesive stamps

Info

Publication number: CA2186759A1
Application number: CA002186759A
Authority: CA
Inventors: John Alec Pike; William James Dorricott
Original assignee: Harrison & Sons Limited; John Alec Pike; William James Dorricott; De La Rue International Limited
Current assignee: De la Rue International Ltd
Priority date: 1994-03-30
Filing date: 1995-03-09
Publication date: 1995-10-12
Also published as: BR9507339A; BG100873A; ES2131817T3; AU694188B2; AP9600877A0; WO1995027278A1; FI963869A; RO115575B1; DE69507604T2; NO964060L; NO964060D0; PL316591A1; GB2288162B; HK1004926A1; CN1145128A; MX9604397A; EP0753187A1; LV11694B; EE9600194A; OA10317A

Abstract

The invention provides self-adhesive stamps comprising: a layer (2) of stamp paper bearing a printed stamp design on its front and having perfo-rated edges (6), a layer of pressure-sensitive adhesive (5) on the back of the stamp paper, and a peelable backing sheet (7) covering the adhesive, wherein the pressure-sensitive adhesive layer is patterned such that there is little or no adhesive adjacent to the per-forated edges of the stamp paper. Preferably, the pressure-sensitive adhesive is a hot-melt adhesive, and preferably the adhesive is applied by printing.
The invention also provides a method of making such stamps comprising the steps of: providing a sheet or web of stamp paper having lines of perforations defining stamps therein, followed by coating the back of the stamp paper with a patterned layer of pressure-sensitive adhesive and a peelable backing sheet.

Description

wo 95l27278 SELF--ADTT~IVE SI~AMPS
; The present invention relates to self-adhesive stamps which may be used for a variety of ~uLyGses, such as fiscal 5 stamps, redemption stamps, savings stamps, gift stamps etc.
In particular, it relates to self-adhesive postage stamps.
Conventional postage stamps are provided with a backing layer of water-soluble adhesive that must be moistened prior 10 to a~fixing the postage stamps to an envelope or mail piece.
In recent years, a demand has developed for self-adhesive postage stamps provided with a coating of ~l ~SaUL_ sensitive adhesive that does not need to be moistened prior to use.
SUC~I self-adhesive stamps are merely peeled off a releasable 15 bac]cing sheet and then pressed onto an envelope or mail piece. The layer of pressure-sensitive adhesive forms a bond between the stamp and the mail piece substrate. In this way, the mess and unreliability of the moistening step nPr~ccAry with conventional postage stamps is avoided.
Existing self-adhesive postage stamps are manufactured from sel~-adhesive label stock or ~IUL~JO_~ prepared self-adhesive stock. The self-adhesive stock consists of a sheet of coated paper bonded to a peelable backing sheet by a layer 25 of ~JL ~ UL~ sensitive adhesive. The backing sheet can be pee]ed of ~ (or the stamp can be peeled from a backing board) to expose the pL~'S uLe-sensitive adhesive, which has been applied as an all-over coating. The ~L~e~uL~ Densitive adhesive is normally an aqueous based polymer adhesive. The 30 self-adhesive postage stamps are manufactured from the said adhesive stock by, first, printing a plurality of postage sta~p designs on the prepared stock, followed by die cutting the coated paper (but not normally the backing sheet) along the edges of the postage stamp designs, so that individual 35 postage stamps can be peeled off the backing. Self-adhesive postage stamps made in this way are currently available in several countries, i nr.lll-l; n~ France, Australia and the USA.

` 21 86759 a Self-adhesive stamps comprising a layer of stamp paper and a layer of pressure-sensitive adhesive mounted on a backing sheet are described in GB-A-1414777, GB-A-2048817 and DE-A-4215834.

2~ 86759 Wo ss/27278 ~ 5 The self-adhesive postage stamps made as described above suffer from numerous drawbacks. Pirst, the coated paper used for making label stock is not nor~ally ideally-suitable for high quality postage stamps. When printing on paper 5 which is part of a self-adhesive sandwich it is seldom possible to obtain the best print quality. The coating on the paper may or may not contain the l~lm;np~r~nt '-conventionally i nrl~ d on postage stamp papers for recognition by automatic sorting r--h i n~ . Still more 10 importantly, the rAnrPl l Ation marks applied to the stamps by the Post Office can sometimes be wiped off the coated papers used for making the self-adhesive stock.
A second drawback of the above method is the impracticality 15 of making traditional perforation holes with the adhesive and release backing in situ. The problem is that the pieces of adhesive-coated paper punched out by a conventional perforating die tend to stick together in unmanageable clumps that obstruct the perforating r--hinPry.
20 This means that the self-adhesive stamps obtained by the above process do not currently have perforated edges. That is to say, they do not have edges with the characteristic pro~ile ~L~,duced by tearing or die cutting along a line of perforations (such as a line of circular holes approximately 25 0.75 - 1.2 mm in ~iii er spaced 0.2 - 0.8 mm apart, measured between edges of ad~acent holes). The absence of perforated edges makes forgery of the stamps easier, and results in reduced customer a..cc:~L~ . This drawback has been addressed by die cutting around the stamps using a die 30 cutting tool having a zig-zag or wave-shaped blade so as to simulate the appearance of perforated edges. Elowever, the stamps produced in this way are always readily disting~ h~hl~ from stamps having true perforated edges when PYAmino-l by experienced persons.
A third drawback of self-adhesive stamps produced according to the existing art is leakage of adhesive through the die-cut lines in the stamp paper. This leakage of adhesive can cause unwanted adhesion between stacked or coiled sheets of the self-adhesive stamps.
A fourth drawback of self-adhesive stamps produced according 5 to the existing art is that the combined thickness of the coated paper, adhesive and backing sheet is difficult to fold into the neatly folded sheets dispensed by postage stamp vending machines or sold in booklets or wallets at Post Offices and other retail outlets.
According, it is an object of the present invention to provide improved self-adhesive stamps that overcome the above drawbacks of the existing art. Tt i5 a further object of the present invention to provide a simple, efficient and 15 productive method of making such improved self-adhesive stamps. The method permits the manufacture of the whole range of conventional stamp based products currently being produced world-wide in self-adhesive forms without variation to the print method, print quality, quality of perforation 20 holes or the overall visual appearance.
The present invention provides a self-adhesive stamp comprising: a layer of stamp paper having perforated edges;
a layer of pressure-sensitive adhesive on the back of the 25 stamp paper; and a peelable backing sheet covering the adhesive, characterized in that Ihe pressure-sensitive adhesive layer is patterned such that there is substantially no adhesive adjacent to the perforated edges of the stamp paper .
The term "perforated edges" means that the edges of the stamp paper have the characteristic prof ile produced by tearing or die cutting along a line or perforations. The said perforations may be circular, polygonal, star shaped or 35 of more complex shapes. However, preferably the perforations are circular. Preferably, the circular perforations have a diameter of 0.75-1.2mm and are spaced o. 2-0 . 8mm apart, measured between edges of ad jacent holes.
~ ElYDED Sl lEEr 3a The provision of self-adhe6ive stamFs having genuinely i 21 8675q WO 95/27278 ~ .'C

perforated edges is an important feature o~ the present invention. Such self-adhesive stamps are harder to forge than previous self-adhesive stamps, ancl are more acceptable to the public.
Preferably, the stamp is a postage stamp. Preferably, the stamp forms part of a sheet or coil of stamps, in which the lndividual stamps are preferably separated from each other by lines of perf orations . The stamps according to the 10 present invention could form part of a sheet or coil of stamps that further comprises stamps not falling within the scope of the invention, for example stamps having only a layer of moistenable adhesive.
15 The term "stamp paper" P -CCe5 any kind of paper suitable f or the manuf acture of stamps . Pref erably, the front face of the stamp paper is provided with a coating that cnn~AinC, in addition to other ~ L " lllminPCCPnt pi, L5 for recognition by automatic facing, cAnrel 1 inq and 20 sorting m--hinPc. Preferably, the front surface of the stamps is printed with a stamp design, such as a postage stamp design. Preferably, the front face of the stamp paper is coated in such a way that it permanently retains cAnrPl7Ation marks applied to the paper by the Post Office 25 or user authority. In fact, the stamp paper is preferably similar to, or the same as, the paper conventionally used l'or the manufacture of postage stamps bearing a water-soluble adhesive coating.
30 In certain preferred Pmho~7i- Ls, the security of the stamp is PnhAnrPC7 by providing shaped perforations, known as perfins, in the central part of the stamp paper remote from the perf orated edges .
35 The ~)LeS::.UL~ 3cnsitive adhesive may comprise any of the adhesives of this type commonly known in the art. For example, the ~JLeS::~UL. sensitive adhesive may be a water-soluble acrylic adhesive. However, preferably, the WO 95/27278 1 ~,II~D7~ O~

~resDuL~ 3ensitive adhesive is a hot-melt adhesive. The ~L~s~uL-:-sensitive adhesive can be applied by any methods that imparts a controlled pattern to the adhesive.
. , .
5 Preferably, the layer of pressure-sensitive adhesive is pri3lted or slot coated on the back of the stamp paper, or in some cases may be similarly applied to the backing sheet and the3l laminated to the rear of the stamps. The ~L~.. UL_ sensitive adhesive does not cover the whole of the back 10 surface of the stamp paper, but instead is patterned such that there is little or no adhesive adjacent to the perforated edges of the stamp paper. Preferably, an adhesive-free margin of 0.1 to 5 mm, more preferably 1 to 4 mm, is left between the perforated edges of the stamp paper 15 and the edge of the pattern of ~1 ~S:~U~ nsitive adhesive.
This ensures that no adhesive leaks through the perforations to the front face of the stamps. Fur~h~ e ~ this makes it easier to peel the stamps away from the backing sheet, since tbe edges of the stamps are not adhered to the ~acking 20 she~t.
Preferably, the FeQl ~hle backing sheet is a relea-e ~oated paper, such as a ci l i conQ-coated paper. Also preferably, the backing sheet may be a polymer film, such as a hiAl~iAlly 25 oriented polypropylene film, which may have been silicone coated .
Preferably, the self-adhesive stamp according to the present invention further comprises a layer of water-rpl~AcAh~e 30 adhesive intercalated between the stamp paper and the layer of l~ SI~UL~ a~nsitive adhesive Preferably, the water-releasable adhesive is a moistenable adhesive of the kind conventionally used for postage stamps. The purpose of this int~ -3iAte layer of water-rQleA~Ah~Q adhesive is to make 35 it possible for philatelists to remove the stamp from an envelope by steaming or soaking . This is dif f icult and not particularly QfficiQrt if there is only a layer of ~L~S~ULI~
sensitive adhesive between the stamp paper and the envelope or postal item.
The present invention also provides a method of making a self-adhesive stamp comprising the steps of: providing a web 5 or sheet of stamp paper and providing lines of perforations in the stamp paper defining a plurality of stamps, followed by applying a layer a layer of pressure-sensitive adhesive and a peelable backing sheet to the back of the stamp paper, characterized in that the pressure-sensitive adhesive is 10 applied in a pattern such that there is substantially no adhesive applied to the back of the stamps adjacent to the lines of perforation.
Preferably, the stamp paper is a conventional stamp paper of 15 the kind used to print conventional postage stamps. Such paper is preferably provided with a continuous layer of moistenable adhesive on the back thereof.
Preferably, the pressure-sensitive adhesive layer is applied 20 to the back of the perforated stamp paper, and the adhesive coated, perforated layer is then laminated to the peelable backing sheet. However, it is also possible to coat the pressure-sensitive adhesive layer onto the backing sheet and then laminate the coated backing sheet onto the stamp paper.
~he method of the present invention offers the advantage that the stamps can be printed using conventional web or sheet printing techniques, such as web gravure printing, on conventional stamp paper that is optimised for such printing 30 and which can also be provided with suitable luminescent coatings for recognition by automatic sorting machines. The printing can be carried out before the perforation step, or it ma~ preferably be carried out following the step of applying the pressure-sensitive adhesive and the backing

3 5 sheet .
The pressure-sensitive adhesive is preferably a hot-melt AME~'D SHEET

Wo 95l27278 F~ .. ,5 C

adhesive. This is preferable because the hot-melt adhesive can be app1ied in one step, without any need for subsequent drying of the adhesive thus having minimal impact on the stamp stability. In contrast, conventional acrylic or other 5 polymer ~L~s~uL~-sensitive adhesive is normally applied in aqueous solution and then dried. This involves an additional step of drying, and the water (or other solvents usel) can cause wrinkling, distortion or other problems with the stamp paper . The ~L~S` UL ~. s~nsitive adhesive may be 10 applied to the back of the stamp paper or to the backing she~t by any conventional means for applying a pa~L~:-.,ed lay,er, such as a nozzle, slot die or roller. Preferably, the yL~:SZ.UL~ .cnsitive adhesive is applied to the back of the stamp paper or to the backing sheet by printing, more 15 pre~erably screen printing. This permits accurate patterniny of the layer of pressure-sensitive adhesive. In par~icular, it allows the pr~uL- scnsitive adhesive to be applied in a pattern such that there is no adhesive adjacent to the perf orated edges around each stamp . Pref erably, an 20 adhesive-free margin of width 0.1-5 mm, more preferably 1-

4 rlm, is left on the back or' each stamp around the perforated edges of each stamp. The advantages of such a patterned adhesive layer are described above.
25 Following the application of the adhesive layer and backing sheet, the method preferably further comprises the step of die cutting the web of stamp paper along one or more of the lines of pc-LuL~tions. This allows individual stamps to be lifted off the backing sheet. The line of the die cut is 30 preferably a straight line running down the middle of the lines of perforations, whereby the stamps are provided with the characteristic perforated edge profile of conventional stamps .
35 The resulting web of self-adhesive stamps adhered to the backing sheet can be cut into smaller sheets and/or wound into coils or made into books or wallets. The web can also be folded readily along the lines of perforations provided Wo 9~/27278 P~ C ~ 1 in the stamp paper. This folding is preferably assisted by the provision of lines of weakness such as score lines or lines of perforations in the backing sheet co~ ,u~Ain~ to the desired fold lines.

Preferably, the self-adhesive stamps are made in a spaced-apart arrA , L on the backing sheet, thereby making the stamps easier to detach from the backing sheet and making it easier to fold up the sheet of stamps. Alternatively for 10 non-spaced apart stamp material the backing paper i5 offset in register to further facilitate peeling by the user. The spaced-apart stamps are made by printing the plurality of stamp designs on the web of stamp paper in a corr~ r~nA;n~J
spaced-apart arr~n~, L with a carcase of blank stamp paper 15 def ined by the lines of perf orations around the stamp designs. Then, following the application of the pe~ hle backing sheet and the adhesive layer, the stamp paper is die cut along the lines of perf orations and the carcase is ll~ted off, thereby leaving a plurality of stamps attached 20 to the backing sheet in spaced-apart fashion. Preferably, little or no E/L~ U~- Ecnsitive adhesive is applied to the back of the carcase, thereby making the carcase easy to separate from the backing sheet, easy to remove and wind up and easy to dispose of. This is an important advantage of 25 the method of the present invention.
Specific ~i Ls of the self-adhesive stamps and method of their manufacture according to the present invention will now be described further, by way of example, with reference 30 to the ~ nying drawings, in which:-Fi~re 1 shows a side elevation view of the stamp accordingto the present invention (relative vertical dimensions have been tu~rlyyu~ ~Ited for the sake of clarity);
Fiqure 2 shows a rear plan view of the stamp of ~igure 1 with the backing sheet removed;

21 86759 wo 9s/27278 P~ ,5 ~ -Fi~ure 3 shows a schematic view of steps in a method of manufacture of a self-adhesive stamp (excluding the printing and final finich;n~) according to the present invention,;
and Fi~ure 4 shows a plan view of a small part of a printed stamp paper web for use in the method of making self-a&esive stamps that are spaced -apart on a backing sheet.
10 Referring to Figure 1, the self-adhesive stamp l1) comprises a layer of stamp paper (2) of the type conventionally used for printing postage stamps according to the existing art that are provided with a layer of moistenable water-soluble adhesive only. A postage stamp design is printed on the 15 fro~rlt surface (3) of the stamp paper, and the front of the sta~np paper can also be coated with a lllmi nPcr~Pnt organic (or inorganic~ pigment for recognition by automatic sorting r~ ; nPc . The back f ace of the stamp paper is entirely coated with a layer (4) of moistenable water-rPlP~c~hle 20 adhesive of the kind that is applied to conventional postage stamps. Beneath the layer (4) of moistenable water-rPlr~c~hlP adhesive, there is provided a layer (5) of hot-mel1: ~L-_~ULI_ sensitive adhesive. The layer (5) of ~L~::a UL~_ scnsitive adhesive does not extend all the way to 25 the edges (6) of the stamp paper. The hot-melt adhesive is a synthetic thermoplastic rubber based adhesive for app3 ication at 150 to 170C and available from The National Starch rhPr; ~ Company Limited under catalog reference no.
089--1540. The weight of the hot-melt adhesive is 10 to 25 30 grams per square metre, preferably 15 to 20 grams per square metre, more preferably about 17~ grams per square metre.
The layer (5) of ~Lea~uL~-sensitive adhesive is covered by a peelable backing sheet (7) of silicone release-coated paper. The particular paper used in this Prhor~;- L is 35 available from Cotek Limited under reference BB 45, and has a w~ight of 45 grams per square metre.
Referring to Figure 2, it can be seen that the stamp (l) has wo 95l27278 .

perforated edges (6) formed by making a straight cut along the centre of a line of circular perf orations . The layer

(5) of p~essure-sensitivè adhesive is screen printed in a rectangular pattern in the centre of the stamp, leaving a 5 margin (8) approximately 3 mm wide free from adhesive around the edges of the stamp. This prevents leakage of the adhesive around the perforated edges of the stamp to the front face of the stamp, and also makes peeling of the stamp from the backing sheet easier.
Ref erring to Figure 3, the self -adhesive stamps are made as follows. First, a web of stamp paper having its back surface entirely coated with conventional water-releasable postage stamp adhesive is printed with a plurality of stamp 15 designs on one face and perforated in the same fashion as for the manufacture of conventional stamps. This ~- uduces a roll t9) of printed and perforated web. In alternative ~mhorli- L" the printing step can be omitted or left until a later stage in the process . The web ( 10 ) is then unwound 20 from the roll (9) and continuously fed into a screen printer (11) that prints the pattern of hot-melt adhesive on the back face of the stamp paper, in register with the printed stamp designs. The screen printer (11) is a hot melt screen printer available from Meltex Gmb~ of L~lneburg, Germany or 25 Nordson Corpor~tion, Norcross, Atlanta, U.S.A. Following the screen printing step, a continuous web ( 12 ) of the backing sheet material is applied to the adhesive-coated surface of the stamp paper web by rollers (13). Optionally, the backing sheet is printed by a web printer ( 14 ) bef ore 30 being applied to the stamp paper web. The resulting sandwiched web (15) then enters a die cutting apparatus t16), in which die cuts are made through the stamp paper along some or all of the lines of perforations in the stamp paper . Where appropriate, the carcase ( 17 ) of stamp paper 35 between spaced-apart stamps is then stripped off and wound up. The web of backing sheet material having the self-adhesive stamps thereon (18) is wound up into a coil (19) or can be sheeted at (24). The coil (19) can then undergo 21 ~6759 wo 95l27278 P~l/~,1,55 C-- -further procPcc;n~ to prep2re sheets, folded sheets, wallets or other retail formats. In alternative Pmho~i- t~, pri~ting of the stamp designs on the front face of the stalrlps can take place at this stage.

Figure 4 shows in detail a section of the perforated, pri~ted web (20) of stamp paper that is used to make stamps according to the present invention spaced-apart on a supporting sheet of peelable backing material. The web has 10 individual stamp designs t21) printed in spaced-apart fasl~ion with lines of perforations (22) around each stamp design (21). In the adhesive coating step, the hot-melt adhesive is printed onto the back of the stamp paper web only on the underside of the stamp designs (21). The 15 bac~cing sheet is then applied, followed by die cutting along the lines of perforations (22). The carcase (23) of stamp paper between the individual stamps can then simply be lift:ed off, leaving the individual stamps spaced-apart on the bac~cing sheet . The carcase is rolled up and tl i ~r,~cp, 2 O of, or recycled .
The above specific Plnho~i - Ls of the present invention have been described by way of example only. r~any other od;- Ls falling within the scope of the ~ ying clai.ms will be ~ nt to the skilled reader.

Claims

12

1. A self-adhesive stamp (1) comprising: a layer of stamp paper (2) having perforated edges (6), a layer of pressure-sensitive adhesive (5) on the back of the stamp paper and a peelable backing sheet (7) covering the adhesive, characterized in that the pressure-sensitive adhesive layer (5) is patterned such that there is substantially no adhesive adjacent to the perforated edges (6) of the stamp paper.

2. A self-adhesive step according to claim 1, wherein a margin (8) of 0.1-5 mm is left between the perforated edges (6) of the stamp paper (2) and the edge of the layer of pressure-sensitive adhesive.

3. A self-adhesive stamp according to claims 1 or 2, wherein the stamp forms part of a sheet (2) or coil of stamps separated by lines of perforations.

4. A self-adhesive stamp according to claims 1, 2 or 3, wherein the pressure-sensitive adhesive is a hot-melt adhesive.

5. A self-adhesive stamp according to any preceding claim, wherein the layer (5) of pressure-sensitive adhesive is printed or slot die coated on the back of the stamp paper (2).

6. A self-adhesive stamp according to any preceding claim, wherein the peelable backing sheet (7) is a release-coated paper, a release-coated board or a polymer film which may be release-coated.

7. A self-adhesive stamp according to any preceding claim further comprising a layer of water-releasable adhesive (4) between the stamp paper and the layer of pressure-sensitive adhesive.

13 3. A self-adhesive stamp according to any preceding claim further comprising a luminescent material applied to the front surface of the stamp.

9. A self-adhesive stamp according to any preceding claim further comprising a printed stamp design on the front surface of the stamp.

10. A method of making a self-adhesive stamp comprising the steps of:
providing a web or sheet (20) of stamp paper and providing lines of perforations (22) in the stamp paper defining a plurality of stamps (21), followed by applying a layer of pressure-sensitive adhesive and a peelable backing sheet to the back of the stamp paper, characterized in that pressure-sensitive adhesive is applied to a pattern such that there is substantially no adhesive applied to the back of the stamps adjacent to the lines of perforations (22).

11. A method according to claim 10, wherein an adhesive-free margin of 0.1-5 mm width is left on the back of the stamps (21) adjacent to the lines of perforations (22).

12. A method according to claim 10 or 11, wherein a plurality of stamp designs is printed on the web or sheet of stamp paper before the lines of perforations (22) are provided in the stamp paper.

13. A method according to claim 10 or 11, wherein a plurality of stamp designs is printed on the web or sheet of stamp paper after the steps of perforating and applying, and in register with the plurality of stamps (21).

14. A method according to claim 10 or 11, wherein the step of applying comprises the steps of: coating the layer of pressure-sensitive adhesive onto the back of the perforated stamp paper, followed by laminating the back sheet onto the coated and perforated stamp paper.

15. A method according to any of claims 10 to 13, wherein the step of applying comprises the steps of: coating the layer of pressure-sensitive adhesive on the peelable backing sheet, followed by laminating the coated backing sheet onto the perforated stamp paper.

16. A method according to any of claims 11-15, wherein the pressure-sensitive adhesive is a hot-melt adhesive.

17. A method according to any of claims 11 to 16, wherein the layer of pressure-sensitive adhesive is coated onto the back of the stamp paper or onto the backing sheet by screen printing or slot die coating.

18. A method according to any of claims 10 to 17, further comprising the step of, following the application of the backing sheet, die cutting the web of stamp paper (20) along one or more of the lines of perforations (22).

19. A method according to any of claims 10 to 18, further comprising the step of die cutting the backing sheet or perforating the backing sheet.

20. A method according to any of claims 10 to 18, wherein the plurality of stamps (21) are spaced apart on the stamp paper (20), with a carcase of stamp paper between the stamps (21) defined by the lines of perforations (22) around the stamps, and the method further comprises the steps of:
following the application of the peelable backing sheet, die cutting along the lines of perforations (22) and lifting off the carcase, thereby leaving a plurality of stamps (21) attached to the backing sheet in spaced-apart fashion.