GB2464142A

GB2464142A - Security fibres for use in security papers with counterfeit protection

Info

Publication number: GB2464142A
Application number: GB0818265A
Authority: GB
Inventors: Gary Donald Spinks
Original assignee: DW Spinks Embossing Ltd
Current assignee: DW Spinks Embossing Ltd
Priority date: 2008-10-06
Filing date: 2008-10-06
Publication date: 2010-04-07
Anticipated expiration: 2028-10-06
Also published as: EP2342085A1; GB0818265D0; WO2010040991A1; GB2464142B; ES2432189T3; EP2342085B1

Abstract

A security fibre 51, 52, comprises a coloured region 21-24 and a margin 31-34 adjacent to the coloured region. The fibre may include a second margin; preferably the margin(s) are unprinted and/or transparent. The coloured region may comprise coloured stripes or a pattern, preferably the region is only visible under UV light. The fibre may comprise a layer of varnish over at least the coloured region. The fibre may be printed on a transparent substrate or a substrate with no background luminescence. Methods of manufacturing security fibres and manufacturing paper products containing the security fibres are also disclosed.

Description

Rainbow Paper-Fibres The present invention relates to security fibres for use in security papers with counterfeit protection. In particular, the invention relates to security fibres having a number of coloured fluorescent stripes or regions. The invention also relates to a method for producing such fibres, and paper products incorporating such fibres.

It is well known to provide security paper products, such as bank notes, cheques, passports, identity papers and fiduciary papers, with some form of counterfeit protection. The counterfeit protection measures may include watermarks, holograms, the provision of one or more metallic strips though the paper, the use of fluorescent particles and the use of optically variable inks and coatings.problems with known counterfeit protection measures include the expense of some mesures and the ease with which some measures can be overcome, for example by utilising methods including digital and laser printing, scanning, photography and xerography.

Security fibres are also a well known security feature used in paper making. Such fibres are small strips of paper, for example approximately 4mm x 0.3mm. Security fibres are added to the paper pulp during manufacture and become embedded in the sheets of paper that are produced. The security fibres are often invisible in daylight and remain unseen by the naked eye. However, when irradiated by ultra-violet light they become fluorescent and visible in the sheet of paper.

Mono-colour fibres are relatively easy and inexpensive to produce. However, counterfeiters have been able to use highlighter-type fluorescent marker pens to simulate mono-colour fibres in a sheet of paper. Invisible fluorescent inks are becoming widely available, and the ease of the counterfeiting process,, rnking a few pen strokes on a sheet of paper, are reducing the effectiveness of mono-colour fibres as a security device.

One solution is to make security fibres comprising different colour regions, which raises the difficulty and cost of producing counterfeit fibres. Such security fibres are described in detail in European Patent Number 1546458. The security fibres become much more difficult to simulate if the different colour regions are printed with a particular colour sequence, for example, the colours of a national flag.

Such security fibres are very small, for example, approximately 4mm x 0.3mm, as it has been found larger fibres or other larger types of security element are difficult to incorporate into the paper and are easily removed. This may be a particular problem when printing bank notes, which undergo several print processes using high pressure and high tack inks. Larger security fibres may be accidentally removed during the printing process, causing the paper to be rejected.

Producing such a small fibre with different colour regions, in particular different colour regions with distinct colour combinations in register with and in the same pattern as all of the other small fibres produced, is a highly difficult process. In the existing process, the pattern is printed on a large surface area of material and then small fibres are cut from the large surface area; however it is difficult to cut the fibres in perfect registration. Existing methods of high-volume cutting of material do not provide a means of registering the print with the cutter and many fibres are produced that do not have colours in register with each other. Existing methods do not allow the cutting to be controlled consistently within a tolerance between 0.125mm and 0.25mm which is believed to be the maximum tolerance for the colours in the fibre to appear to be equal in size and position.

The present invention seeks to mitigate or overcome one or more of the above-identified disadvantages associated with

the prior art.

The invention provides a security fibre for use in counterfeit protection, the security fibre being suitable for incorporation into a paper product, the security fibre comprising a coloured region, wherein the coloured region is S 4 made up of a plurality of different colours, and a margin adjacent to the coloured region.

Preferably, the margin comprises an unprinted region of the security fibre. The margin may provide a greater adhesion when embedded as a security fibre in a paper product than a security fibre without such a region. Preferably, margin is an unprinted region of the security fibre which provides greater adhesion when embedded as a security fibre in a paper product than a security fibre without an unprinted region.

The coloured region of the security fibre may include a varnish to make the coloured region impervious to water or hydrophobic. Advantageously, this prevents the coloured region being degraded when the security fibre is being mixed with paper pulp or in a later printing process. The varnish may increase the abrasion resistance of the coloured region of the security fibre. However, such a varnish may reduce the adhesion of the coloured region of the security fibre with the paper product in which it is to be embedded. Advantageously, the margin is unprinted, and/or porous, which increases the adhesion between the paper fibre and a paper product in which it is embedded.

The coloured region may be visible only under ultra-violet light. Preferably thecoloured region fluoresces under ultra-violet light. Providing a coloured region that is visible only under ultra-violet light enables counterfeit protection to be added to paper which is not visible with the naked eye.

Preferably, the margin is not visible under ultra-violet light. Preferably, the security fibre comprises a second margin adjacent to the coloured region, such that the coloured region is situated between the first and second margins.

Advantageously, the margin or margins adjacent to the coloured region introduce a margin of error when producing the fibre. The security fibre may be cut from a substrate, for example a sheet of paper, such that the cutting takes place in the margin or margins. A certain level of inaccuracy during the cutting process can thus be tolerated, as it no longer affects the appearance of the coloured region, which will still appear to be in perfect register.

The coloured, region may be a printed on the both the front and the rear sides of the security fibre. The security fibre may be printed on both its front and its rear sides by printing on one of the front and rear sides and allowing the ink to soak through to the other side of the security fibre.

Alternatively, the security fibre may be printed on both its front and its rear sides by printing on one side of the security fibre and then printing on the other side of the security fibre.

The margin or margins may be transparent. The security fibre may be printed on a paper, preferably transparent paper.

Alternatively, the security fibre may be printed on a plastic or cellulose based substrate. It may be that the material on which the security fibre is printed has no background fluorescence. The margin or margins may completely surround the first, coloured, region. The margin or margins may extend from 0.5mm to 5mm from the edges of the coloured region to which they are adjacent.

The coloured region may comprise a plurality of different coloured stripes. There may be two, three, four or more stripes in the first, coloured, region. The said striped regions may include any or all of the colours red, green, yellow, and blue. The stripes may be placed at approximately 1mm graduations. The stripes may appear in the same order in a repeating pattern. Advantageously, the stripes appearing in the same order in a repeating pattern makes it more difficult to forge the paper fibre. The coloured region may be rectangular in shape. The coloured region may measure between 3mm and 5mm in length, and 0.2mm to 1mm in width. The coloured region may comprise a more complex pattern than stripes. For example, the coloured region may be a two dimensional pattern. The coloured region may include an image of a flag, and/or a combination of numbers and/or letters or some other recognisable image.

The margin or margins may extend from 0.5mm to 2mm from the edge of the coloured region to which they are adjacent.

The security fibre may range between 3.5mm to 9mm in length, and 0.2mm and 6mm in width. Preferably, the coloured region is S located approximately at the centre of the paper fibre, with the second and third regions located at each end of the paper fibre.

Preferably, the security fibre is a 5mm, 6mm, or 7mm long security fibre with a first, coloured, region of 3mm, 4mm, or 5mm respectively. However, it is clear that the invention can be applied such that a security fibre with a larger length and/or width is produced. The dimensions of the coloured region and the margin or margins may be increased correspondingly..

The invention also provides a method of manufacturing a security fibre for use in counterfeit protection, the security fibre being suitable for incorporation into a paper product, the method comprising the steps of printing a plurality of coloured regions onto a substrate, , each of the plurality of coloured regions being printed adjacent to at least one margin, and cutting the substrate to create a security fibre including at least one of the coloured regions, wherein the substrate is cut in at least one margin.

Preferably, a margin is simply an unprinted region of the substrate onto which the coloured regions are printed.

Advantageously, the substrate onto which the coloured regions are printed has no background fluorescence under ultra-violet light.

Advantageously, the margins increase the margin of error permitted during the cutting process without the appearance of the coloured regions being affected.

Preferably, coloured regions are visible only under ultra-violet light.

Preferably, the method includes the step of cutting the substrate to create a plurality of security fibres. The plurality of coloured regions may be printed on the substrate in a series of rows. Each coloured region may comprise a plurality of colours printed side by side. The plurality of colours may be printed to form stripes. There may be two, three, or tour stripes printed in each coloured region. The stripes may include any or all of the colours red, green, yellow, and blue. The plurality of colours may be printed to form amore complex pattern than stripes. The coloured region may comprise a more complex pattern than stripes. For example, the coloured region may be a two dimensional pattern.

The coloured region may include an image of a flag, and/or a combination of numbers and/or letters or some other recognisable image.

S

Each coloured region may be located between two margins are unprinted areas of the substrate. The printing of the plurality of the coloured regions in this way may create a corrugated effect due to the raised level of the coloured regions once the ink has been printed on the substrate, such that when one piece of substrate printed in this way is stacked on top of another piece of substrate printed in this way, the sheets fall into a natural alignment. Preferably, several sheets of substrate are stacked on top of each other and are cut simultaneously. The stack of sheets ofsubstrate to be cut may be between 10mm and 20mm high. The natural alignment of the sheets of substrate, together with the cutting taking place within the margins, allows the cutting process to deviate, for example, by up to 1mm without any affect on the appearance of the coloured region of the paper fibre. For example, the coloured region will be, and will appear to be, 4mm long and in the correct red, green, blue, and yellow proportion, despite the variance in the cutting of the security fibre. The cutting process may also include the substrate being cut such that the coloured regions are cut perpendicular to the cuts made along the margins. As these cuts are across the coloured region, the colour sequence of any strips or patterns included in the coloured regions are not affected due to any cutting inaccuracy. The cuts may produce a paper fibre with a length between 3.5mm and 9mm, and a width between 0.1 to 0.5mm.

The cuts may be made with a specially developed knife, the knife being arranged such that it can cut the substrate both in at least one margin and across a coloured region simultaneously. Preferably, the knife is arranged to be able to cut the substrate with a single cut in order to produce the security fibres. Preferably, the knife comprises a crenellated blade.

The method may include the step of the coloured regions being printed on both the front and the rear sides of the substrate. The step of printing the coloured regions on both the front and the rear sides of the substrate may include the substrate being printed on one of its front or its rear sides and allowing the ink to soak through to the other side of the substrate. Alternatively, the step of the coloured regions being printed on both the front and the rear sides of the substrate may include printing on one side of the substrate and then printing on the other side of the substrate.

The substrate may comprise paper. Alternatively, the substrate may comprise a plastics or cellulose-based substrate.

The present invention also provides a method of manufacturing a paper product, wherein the method comprises the steps of mixing a plurality of the security fibres as described above with slurry paper pulp such that the security fibres form a hydrogen bond with the cellulose fibre in the paper pulp and forming the paper pulp and security fibre mix into a continuous web of paper.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings of which: Figure 1 shows an example of a sheet of paper printed according to an embodiment of the invention; Figures 2a and 2b show example of the paper fibres according to an embodiment of the invention; and Figure 3 shows an example of a knife blade used to cut the security fibres.

Figure 1 shows a piece of substrate 1, onto which a plurality of coloured regions 2 have been printed. The coloured regions 2 are visible only when viewed under ultra-violet light. The coloured regions are generally rectangular in shape and are made up of four different coloured stripes, 21, 22, 23, and 24, printed side by side. The four different colours 21, 22, 23, and 24, are fluorescent colours that are visible only under ultra violet light. The colours may include any or all of red, green, yellow, and blue. In one embodiment, the colours are visible when ultra-violet light having a wavelength of between 245nm and 365nm is shone at the fibre. In any particular embodiment and for any particular

S

colour, the wavelengths at which the colours are visible are dependent on the pigments used to generate the prints.

In this embodiment of the invention, both sides of the substrate 1 are printed with the coloured regions 2. In this case, the substrate 1 is a thin and porous paper and printing on a single side of the substrate 1 with an appropriate amount of ink means that the ink soaks through the substrate 1 and so both sides of the substrate 1 have been printed on. In an alternative embodiment, each side of the substrate 1 is printed individually, such that the coloured regions 2 on each side of the paper line up in perfect register with each other.

Figure 1 shows three coloured regions 2 printed on the substrate 1. Adjacent to the coloured regions 2, and separating the coloured regions 2 from each other, there are a number of margins 3 that are not visible under ultra-violet light. In this case, the margins 3 that are not visible under ultra-violet light are areas of the substrate 1 that have not been printed. The printing of the coloured regions 2 and the margins 3 not being printed creates a minor corrugated effect due to the printed regions being slightly raised in comparison with the unprinted regions. The corrugated effect can advantageously be used when stacking several sheets of similarly printed substrate 1, as it brings the sheets substrate 1 into natural alignment with each other. The cutting of the substrate 1 can then advantageously be performed with several sheets of substrate on top of each other, thus saving time and effort.

Figure 1 also shows, with dashed lines, the pLanned cut lines 4. In figure 1 the only the cut lines parallel to the margins are shown, in order to best demonstrate the advantages of the invention. Figure 3 shows the cutting outline of a knife which is designed to cut the substrate 1 in such a way that a single cutting step can produce rectangular security fibres. The knife comprises a blade with a crenellated cutting edge. The size of the crenulations corresponds to the size of the security fibres. The knife is brought down onto the stack of the sheets of substrate, thus cutting out a number of rectangular security fibres. The sections of the knife blade that are designed to cut along the cut lines 4 shown as parts 41, and the sections of the knife blade that cut across the coloured regions 2 are marked 42. The knife or the sheets of substrate may then be moved and a further cut made, thus creating more security fibres.

Due to the margins 4 between the coloured regions 2, deviations of the cutting from the planned cut lines 4 by a certain amount can be tolerated without affecting the shape, size and appearance of the coloured regions 2.

The substrate 1 from which the security fibres are produced in the embodiment of the invention as described above is a tissue or thin paper without optical brighteners. The optimum paper is a high porosity, high wet strength tissue paper with a nominal basis weight of 25 grams per square metre. The substance of the paper is significant since the ability to print and cut a thin substrate provides a technical barrier to duplicating the fibres.

Fibres in accordance with the present invention have been manufactured using paper having the properties listed below.

These properties have been developed with the intention of providing a fibre that works well, but are only one example.

Other papers could be used.

Properties Units Minimum Maximum Average Substance g/m2 15 45 24.8 Lemm mm 16 17 16.6 Capillary Climb md Wet Tensile N/lSmm 4.5 5.9 5.14 Strength Bulk Crn3/g 2.4 2.5 2.46 High 1/rnn/lOOcm2 24 31.2 27.9 Porosity Humidity pH % 4.9 7.0 6.8 of aqueous extract In addition, the target Bensten porosity (defined by ISO standard 5636/3) is l500rnl/rnm, the minimum Bensten values is 700 mi/mm.

As described for the embodiment of the invention as shown in Figure 1, four different colour stripes are printed in the coloured regions 2. Suitable products for the printing process have been developed from commercially available pigments. Each of the red, green, yellow, and blue prints has a Blue Wool lightfastness of 3, an excitation wavelength in the region of 365nm and good chemical resistance.

The coloured regions 2 may also be coated with a varnish.

The varnish protects the coloured regions 2 against abrasion and also improves the affinity of the fibres in the finished paper. In one embodiment, the varnish is a 4% solution of Solvitose NX in acrylic water based binder.

Figure 2a shows a paper fibre 51 which has been cut out in accordance with the planned cut lines 4 (and also in the direction perpendicular to the cut lines 4 as described above, such that a thin, approximately rectangular security fibre has been produced) . The security fibre 51 is approximately 5mm x 0.3mm, the coloured region being approximately 3mm long. The coloured region 2 is approximately in the centre of the paper fibre 51, located between two equally sized margins 31 and 32.

The margins 31 and 32 are approximately 1mm long each. Figure 2b shows a security fibre 52, with approximately the same dimensions as the security fibre 51, which has been cut out with a deviation from the planned cut lines 4 due to the cutting machine tolerances. The coloured region 2 is located to the left hand side of the paper fibre 52 as seen on the figure. The coloured region 2 is located between two margins 33 and 34, however, the margin 33 is smaller than the margin 34. However, despite the inaccuracy of the cutting process, when viewed under ultra-violet light, the coloured regions in security fibre 51 and security fibre 52 will appear to be identical.

Paper products in accordance with the present invention are made by mixing slurry paper pulp with the security fibres of the present invention. The security fibres of the present invention form a hydrogen bond with the cellulose fibres in the paper pulp and when the pulp is formed into a continuous web of paper, the security fibres in the pulp become an integral part of the web or sheet of paper. The coloured regions of the fibres can only be seen under ultra-violet light, thereby providing a security feature that cannot be seen in normal light conditions.

Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. For example, the substrate may be a plastics or cellulose-based material. The coloured region may comprise a more complex pattern than stripes, for example, a two-dimensional pattern or a combination of numbers and/or letters. The coloured region may be a representation of a flag or other recognisable image.

Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims.

Claims

Claims 1. A security fibre for use in counterfeit protection, the security fibre being suitable for incorporation into a paper product, the security fibre comprising a coloured region, wherein the coloured region is made up of a plurality of different colours, and a margin adjacent to the coloured region.
2. A security fibre as claimed in claim 1, wherein the margin comprises an unprinted region of the security fibre.
3. A security fibre as claimed in claim 1 or claim 2, wherein the coloured region is visible only under ultra-violet light.
4. A security fibre as claimed in any of claim 1 to 3, wherein the margin is not visible under ultra-violet light.
5. A security fibre as claimed in any preceding claim, further comprising a second margin adjacent to the coloured region, such that the coloured region IS Situated between the first and second margins.
6. A security fibre as claimed in any preceding claim, wherein the coloured region is a printed on the both the front and the rear sides of the security fibre.
7. A security fibre as claimed in any preceding claim, wherein the margin or margins are transparent.
8. A security fibre as claimed in any preceding claim, comprising a transparent substrate.
9. A security fibre as claimed in any preceding claim, comprising a transparent paper.
10. A security fibre as claimed in any preceding claim, comprising a substrate with no background fluorescence.
11. A security fibre as claimed in any preceding claim, wherein the coloured region comprises a plurality of different coloured stripes.
12. A security fibre as claimed in any preceding claim, wherein coloured region comprises a two dimensional pattern.
13. A security fibre as claimed in any preceding claim, wherein the security fibre ranges between 3.5mm to 9mm in length, and 0.7mm and 6mm in width.
14. A security fibre as claimed in any of claims 2 to 13, wherein the coloured region is located approximately at the centre of the security fibre, with the first margin and second margin located at respective ends of the security fibre.
15. A security fibre as claimed in any preceding claim, further comprising a layer of varnish on at least the coloured region.
16. A method of manufacturing a security fibre for use in counterfeit protection, the security fibre being suitable for incorporation into a paper product, the method comprising the steps of printing a plurality of coloured regions onto a substrate, each of the plurality of coloured regions being printed adjacent to at least one margin, and cutting the substrate to create a security fibre including at least one of the coloured regions, wherein the paper is cut in at least one margin.
17. A method as claimed in claim 16, wherein the margins are unprinted regions of the substrate.
18. A method as claimed in either of claims 16 or 17, the method including the step of cutting the substrate in a plurality of margins to create a plurality of paper fibres.
19. A method as clairnedin any of claims 16 to 18, wherein the plurality of coloured regions may be printed on the substrate in a series of rows.
20. A method as claimed in any of claims 16 to 19, wherein each coloured region comprises a plurality of colours printed side by side.
21. A method as claimed in any of claims 16 to 120, wherein each coloured region comprises a plurality of colours printed to form stripes.
22. A method as claimed in any of claims 16 to 21, wherein each coloured region is located between two margins.
23. A method as claimed in any of claims 16 to 22, wherein the plurality of coloured regions are visible only under ultra-violet light.
24. A method as claimed in any of claims 16 to 123, including the further step of stacking at least one substrate on top of another, identical, substrate and cutting the substrates simultaneously.
25. A method as claimed in any of claims 16 to 24, further including the step cutting the substrate in a direction perpendicular to the cuts made in the margin.
26. A method as claimed in any of claims 16 to 25, including the step of printing the substrate with coloured regions on both the front and the rear side of the substrate.
27. A method as claimed in claim 26, wherein the step of printing the substrate with coloured regions on both the front and the rear sides comprises printing on one of the front or the rear sides of the substrate and allowing the ink to soak through to the other side of the substrate.
28. A method as claimed in claim 26, wherein the step of printing the substrate with coloured regions on both the front and the rear sides comprises individually printing on the front side of the substrate and printing on the rear side of the substrate.
29. A method as claimed in any of claims 16 to 28, wherein the substrate comprises a sheet of paper.
30. A method of manufacturing a paper product, the method comprising the steps of: mixing one or more security fibres as claimed in any of claims 1 to 15 or one or more security fibres manufactured using the method of any one of claims 16 to 29 with slurry paper pulp such that the security fibres form a hydrogen bond * with the cellulose fibre in the paper pulp; and forming the paper pulp and fibre mix into a continuous web of paper.
31. A paper product containing a plurality of the * 15 security fibres as claimed in any one of claims 1 to 15 or manufactured using the method of any one of claims 16 to 29.