GB2641023A - Security papers - Google Patents

Abstract

A method of recycling security paper comprising a paper substrate having a first set of inclusions (2) incorporated therein, the inclusions comprising a substrate (16), a printed region (8) and a barrier layer (14) between the substrate and printed region; the method comprising exposing the security paper to a solution which dissolves the barrier layer of the inclusions to separate the ink from the inclusion. Also included are claims to a method of manufacturing such inclusions by applying a barrier composition to a sheet of paper, printing with ink and then cutting the paper to produce the inclusions; claim to the inclusions themselves as described in the method; claims to a security paper containing a paper substrate and a plurality of such inclusions and a claim to a security document comprising said security paper. The solution to dissolve the barrier layer may comprise water and an active solution which may be laundry detergent. The solution may contain sodium or potassium hydroxide.

Description

Security Papers

Field of the Disclosure

The present disclosure concerns improvements in or relating to security papers made from a pulp having a plurality of inclusions (e.g. fibres and/or planchettes) mixed into it. More particularly, but not exclusively, the disclosure concerns recyclable inclusions, a method of recycling security papers comprising such inclusions and security papers comprising such inclusions.

Background of the Disclosure

Security documents, for example banknotes, passports, lottery tickets, tax stamps, some certificates and other items of potentially high value, are targets for counterfeiters, who seek to produce counterfeit copies of the security documents and thus illegally benefit from the high value of the genuine items. Security documents typically include various security devices that are difficult for a counterfeiter to simulate. In order to be effective, a security device must exhibit characteristics that are easily identified by a user seeking to verify the authenticity of the security document concerned whilst increasing the burden for a potential counterfeiter.

A security device may take the form of an inclusion (or particulate), for example a fibre or planchette, that is mixed into the pulp used to produce a security paper.

An example of such an inclusion is a security fibre (hereafter a fibre). EP 1 546 458 (D W Spinks (Embossing) Ltd) discusses examples of such fibres having coloured fluorescent stripes or regions. Such fibres must be durable enough to maintain their appearance over long periods of day to day use, and to resist counterfeiting techniques that may attempt to change their appearance.

However, having such fibres or other types of inclusions in a security paper can make the paper difficult to recycle. Previous attempts at recycling often damaged the security paper substrate such that it could not be reused, have required large amounts of energy and/or involved environmentally damaging chemicals. -2 -

The present disclosure seeks to mitigate the above-mentioned problems. Alternatively or additionally, the present disclosure seeks to provide an improved inclusion, an improved method of recycling security papers, improved inclusions for use in such a method, and security papers comprising such inclusions.

Summary of the Disclosure

The present disclosure provides a method of recycling security paper comprising a paper substrate having a first set of inclusions incorporated therein, wherein each inclusion of the first set comprises a substrate, a printed region and a barrier layer between the substrate and the printed region, the method comprising: exposing the security paper to a solution which dissolves the barrier layer of the inclusions such that the ink of the printed region is separated from the inclusion. In a further aspect, the present disclosure provides an inclusion for use in a security paper, the inclusion comprising: a substrate; a printed region; and a barrier layer between the substrate and the printed region such that when the barrier layer is dissolved the ink of the printed region is separated from the inclusion.

In a further aspect, the present disclosure provides a method of manufacturing an inclusion for use in a security paper, the method comprising applying a barrier composition to a sheet of paper to form a barrier layer; and then printing with ink on the barrier layer; and then cutting the substrate sheet to produce a plurality of inclusions.

In further aspects, there present disclosure provides a security paper comprising a plurality of inclusions according to any other aspect, and/or a security paper document comprising such a security paper.

It will of course be appreciated that features described in relation to one aspect of the present disclosure may be incorporated into other aspects of the present disclosure. For example, the method of the disclosure may incorporate any of the features described with reference to the apparatus of the disclosure and vice versa.

Description of the Drawings

Embodiments of the present disclosure will now be described by way of example only with reference to the accompanying schematic drawings of which: -3 -FIG. 1 shows a plan view of a fibre according to a first example embodiment of the disclosure; FIG. 2 shows a cross-sectional view of the fibre of FIG. 1; FIG. 3 shows a flow chart of an example method of recycling a security paper,

in accordance with the present disclosure; and

FIG. 3 shows a flow chart of an example method of manufacturing an inclusion in accordance with the present disclosure; FIG. 5 shows a plan view of a planchette according to a second example

embodiment of the disclosure;

FIG. 6 shows a security paper in accordance with an example embodiment of the disclosure; FIG. 7 shows the results of a first test comparing the performance of printed strips with and without a barrier layer; and FIG. 8 shows the results of a second test comparing the performance of printed strips with and without a barrier layer.

Detailed Description

In one aspect, the present disclosure provides an inclusion for use in a security paper, the inclusion comprising: a substrate; a printed region; and a barrier layer. The barrier layer is between the substrate and the printed region such that when the barrier layer is dissolved the ink of the printed region is separated from the inclusion.

Thus, inclusions in accordance with the present disclosure may comprise printed regions that can be removed by dissolving a barrier layer located between the printed region and the substrate. This facilitates recycling of the inclusions and/or the security papers in which they are used. For example, this may allow the ink (pigment) to be removed from the inclusion leaving behind a substrate that is not visible in the security paper, for example because it is made from the same material as the rest of the paper substrate. The security paper can then be pulped and recycled into a new sheet of security paper, without the inkless inclusions impacting on the appearance of that new sheet. Additionally, or alternatively, by choosing an appropriate barrier layer the printed regions are removed using relatively low temperatures and/or with -4 -chemicals that are less environmentally damaging, thereby reducing the risk of the security paper being damaged during the recycling process and/or reducing the impact on the environment. Appropriate compounds for use in the barrier layer are commercially available, for example such compounds are used in the packaging industry.

An example of a suitable compound for the barrier layer is Water Based Caustic Soluble Primer MAX 62953 available from Mirage Inks Limited of Frome, UK but other appropriate products are commercially available. A range of appropriate substrates and inks for use in the printed regions are also commercially available. The formulation of appropriate compounds for the barrier layer and/or inks for use in the printed regions is straightforward for manufacturers of such products. Likewise, the selection of an appropriate substrate, barrier composition and inks will be straightforward for the person skilled in the art.

It may be that the bather layer separates the ink of the printed region from the substrate such that the ink does not bond with the substrate. Thus, when the barrier is dissolved the ink of the printed region is separated from the inclusion.

The barrier layer may be a layer of a barrier composition.

It may be that the barrier layer is dissolved by a solution comprising water and an active agent within 30 minutes at 25°C or above, for example at 40°C or above, for example at 60°C. It may be that the barrier layer is not dissolved by water under the same conditions within the same time frame (i.e. within 30 minutes at the same temperature). Providing a barrier layer that is insoluble or only slowly dissolved in water but dissolved rapidly by an active agent may allow the inclusions (and/or the security documents of which they form a part) to withstand day to day handling while still being recyclable.

It may be that the active agent is laundry detergent. It may be that the barrier layer is dissolved by a solution having from 1% (w/w) to 5% (w/w) inclusive, for example from 1% (w/w) to 2% (w/w) inclusive, laundry detergent within 30 minutes at 25°C or above, for example at 40°C or above, for example at 60°C. As used herein, 'laundry detergent' refers to commercially available domestic laundry detergent, for example such as would be available in the laundry detergent aisle of a supermarket. Providing a barrier layer that is soluble in laundry detergent may provide a cost-effective and/or straightforward way of recycling inclusions while allowing for -5 -recyclable inclusions that are robust against the more specialist chemicals often used by forgers to alter security documents.

It may be that the laundry detergent comprises Marseille Soap, for example consists essentially or consists of Marseille Soap. For example, it may be that the active agent is Marseille Soap. It may be that the barrier layer is dissolved by a solution having from 1% (w/w) to 5% (w/w) inclusive, for example from 1% (w/w) to 2% (w/w) inclusive, Marseille Soap within 30 minutes at 25°C or above, for example at 40°C or above, for example at 60°C. Marseille Soap (Savon de Marseille) is a soap made from vegetable oil and alkaline lyes (e.g. sodium hydroxide and/or potassium hydroxide). It may be that the Marseille Soap has 70% (w/w) or greater, for example 72 % (w/w) or greater, vegetable oil. Typically, the vegetable oils will be one or more of olive oil, palm oil, coconut oil, and peanut oil.

It may be that the active agent is sodium hydroxide, potassium hydroxide or a mixture thereof. It may be that the barrier layer dissolves in a solution having from 5% (w/w) to 1% (w/w) inclusive, for example from 1% (w/w) to 2% (w/w) inclusive, for example 1% (w/w) inclusive, of sodium hydroxide, potassium hydroxide or a mixture thereof within 30 minutes at 25°C.

Providing a barrier layer that is dissolved in sodium hydroxide and/or potassium hydroxide may allow the printed regions to be removed using relatively low temperatures.

It may be that the solution has a pH of greater than or equal to 8.0, preferably greater than (more basic) or equal to pH of 8.5, most preferably greater than or equal to a pH of 9.0. Providing a barrier layer that is dissolved in basic solutions may allow for a wider range of solutions.

It may be that the substrate of the inclusion (hereafter the substrate) is made of a cellulose material. For example, the substrate may be made from wood pulp or plant based cellulosic material. The substrate may be transparent. The substrate may be paper. The substrate may be tissue paper. The substrate may be without optical brighteners. The substrate may be paper of a high porosity, high wet strength tissue paper. The tissue paper may having a nominal basis weight of between 12g/m2 and 45g/m2 inclusive, for example between 23 g/m2 and 28 g/m2, for example 25 g/m2. The tissue paper may have a wet tensile strength of from 4 N/15mm to 6 N/15mm inclusive, for example from 4.5 to 5.9 N/15mm. -6 -

It may be that the substrate has a front face. It may be that the substrate has a back face, being the opposite face of the substrate to the front face. It may be that the substrate and/or the inclusion is substantially planar. It may be that the substrate has a thickness of 10 to 50 microns, for example 20 to 40 microns.

It may be that each inclusion is at least 1 mm in length and/or diameter. It may be that each inclusion is not more than 10 mm in length and/or diameter. In the case that the security device is a fibre, the length of the fibre may be from 4.5 mm to 5.5 mm (inclusive) in length. The fibre may be from 0.25 mm to 0.35 mm (inclusive) in width.

It will be appreciated that the barrier layer and the printed region are on the same side of the substrate. Thus, the inclusion may comprise a substrate, a printed region on one side of the substrate, and a barrier layer between the printed region and the substrate. It may be that the printed region is applied to, for example directly onto, the barrier layer. Or, there may be one or more intermediate layers between the barrier layer and the printed region. Likewise, it may be that the barrier layer is applied to, for example directly onto, the substrate. Or, there may be one or more intermediate layers between the barrier layer and the substrate.

It may be that the barrier layer and the printed region are on the same side of the substrate as the front face (i.e. the front side). It may be that the barrier layer extends over the majority of, for example the whole of, the front face. It may be that one or more printed regions extend over the majority of, for example the whole of, the front face. It may be that one or more printed regions extend over the majority of, for example the whole of, the barrier layer.

It may be that the inclusion comprises barrier layer(s) between the substrate and all the printed region(s) of the inclusion. That is to say, it may be that each printed region of the inclusion is separated from the substrate by a barrier layer.

It may be that the inclusion comprises a second barrier layer. It may be that the inclusion comprises another printed region. It may be that the second barrier layer and said another printed region are on the same side of the substrate as the back face (i.e. the back side). It may be that the second barrier layer extends over the majority of, for example the whole of, the back face. It may be that one or more printed regions extend over the majority of, for example the whole of, the back face. -7 -

It may be that there is barrier composition present throughout the majority of, for example substantially the whole of, the substrate. For example, it may be that the substrate has been impregnated with barrier composition throughout the majority of for example the whole of, its thickness, length, width and/or diameter, for example through the majority of, for example the whole of, its volume. The thickness of the substrate may be defined as the distance between the front and back faces of the substrate. It may be that the thickness is (very much) less than the width, length, or diameter of the substrate. It may be the width of the substrate is less than the length.

It may be that the barrier layer separates the printed region from the substrate such that the ink of the printed region is not absorbed into the substrate and/or bonds to the substrate. It may be that the or each barrier layer separates all the printed regions of the inclusion from the substrate, such that no ink is absorbed into the substrate and/or bonds to the substrate.

It will be appreciated that a printed region is a region printed with an ink, for example a water based ink. The inclusion may comprise one or more printed regions.

The inclusion may comprise one or more printed regions on the front side of the substrate. The inclusion may comprise one or more printed regions on the back side of the substrate. It may be that the inclusion comprises a barrier layer between any printed region and the substrate.

It may be that the printed region does not extend over the whole of the surface of the barrier layer. It may be that at least a part of the barrier layer (e.g. a portion of the surface area of the barrier layer on the opposite side of the layer to the substrate) is uncovered, for example exposed to the environment. That is to say, that there is no printed region or any other layer extending over said portion of the barrier layer.

Leaving a portion of the barrier layer uncovered may facilitate the solution reaching the barrier layer in order to dissolve it and/or increase the speed at which the barrier layer is dissolved.

The inclusion may comprise first printed regions, second printed regions and/or further printed regions. The first, second and/or further printed regions (if present) may be located on the same or different sides of the substrate. For example, the inclusion may comprise first printed regions on the front side of the substrate, and second printed regions on the back side of the substrate. Alternatively, the inclusion may comprise first, second and (optionally) further printed regions on the front side of -8 -the substrate. The inclusion may comprise first, second and (optionally) further printed regions on the back side of the substrate. It may be that only a single colour is applied/visible in each printed region under a given light condition.

It may be that the first printed regions are printed with an ink which fluoresces under ultraviolet light to emit visible light of a first colour and/or the second printed regions are printed with an ink which fluoresces under ultraviolet light to emit visible light of a second, different, colour. It may be that the first and/or second printed regions are printed with an ink that is substantially invisible (transparent and colourless) under visible light. Thus, it may be that the printed region(s) are only visible under ultraviolet light. This may produce a striking visual effect which is difficult for counterfeiters to reproduce.

It may be that the first printed regions are printed with an ink that is visible as a third, different, colour under visible light and/or the second printed regions are printed with an ink that is visible as a fourth, different, colour under visible light. If the ink also fluoresces as described above, this may provide a striking visual effect in which the colour of the inclusion changes under visible and ultraviolet light.

It may be that each further printed region appears as a further, different, colour under visible light. It may be that each further printed region appears as a further, different, colour under ultraviolet light. It may be that each further printed region is substantially invisible under visible light.

References to colour and/or visibility above may apply equally to colour and/or visibility in transmission and/or reflection.

It may be that each of the printed regions on the same side of the substrate appears a different colour under visible light and/or a different colour under ultraviolet light.

It may be that each printed region is a stripe, for example extending across the (width of) the substrate. It may be that the printed regions form a repeating pattern along the length or diameter of the substrate.

It may be that each inclusion is a fibre or a planchette. In the case that the inclusion is a fibre, it may be that the substrate is rectangular when viewed in plan. In the case that the inclusion is a planchette, it may be that the substrate is square, circular, triangular, star shaped, or irregularly shaped when viewed in plan. -9 -

In another aspect of the disclosure, there is provided a security paper comprising a plurality of inclusions as described above.

Security papers in accordance with the present disclosure are made by mixing slurry paper pulp with the inclusions (e.g. fibre, planchettes) of the present disclosure.

The inclusions become an integral part of the web or sheet of paper forming the security paper. For example, it may be that the fibres of the present disclosure form a hydrogen bond with the cellulose fibres in the paper pulp. Thus, the security paper may comprise a paper substrate having a plurality of inclusions integrated therein.

It may be that the substrate of each inclusion has substantially the same visible appearance, for example the same colour under visible light, as the paper substrate (the rest of the substrate of the security paper of which the inclusions become an integral part). It may be that the paper substrate has any of the material properties described above in connection with the substrate of the inclusion. For example, the paper substrate may be made of a cellulose material and/or may be a tissue paper substrate etc. It may be that the paper substrate and the substrate of each inclusion are the same material.

It another aspect of the disclosure, there is provided a security document, for example a banknote, passport or other identity document, lottery ticket, tax stamp, or certificate, comprising a security paper as described above.

In another aspect of the disclosure, there is provided a method of recycling a security paper. The security paper comprises a paper substrate having a first set of inclusions incorporated therein. Each inclusion of the first set comprises a substrate, a printed region and a barrier layer between the substrate and the printed region. The method comprises: exposing the security paper to a solution which dissolves the barrier layer of the inclusions such that the ink of the printed region is separated from the inclusion.

The security paper and/or inclusions of the present aspect may have any of the features described above in connection with the other aspects.

The method may comprise, after the ink is separated from the substrate, pulping the security paper (e.g. the paper substrate having the inclusions therein) to produce a pulp. The method may then comprise, adding a second set of inclusions to the pulp. It may be that each inclusion of the second set comprises a substrate and a printed region. It may be that each inclusion of the second set comprises a barrier -10 -layer between the substrate and the printed region. It may be that the substrate of each inclusion of the second set is the same as the substrate of the inclusions of the first set. It may be that the barrier layer of each inclusion of the second set is the same as the barrier layer of the inclusions of the first set. It may be that the printed region(s), for example the appearance of the printed region(s) under visible and/or invisible light, is different as between the first set (prior to exposure to the solution) and second sets. It may be that the security paper is exposed to, for example immersed in, a solution comprising water and an active agent. It may be that the security paper is exposed to the solution for no more than 40 minutes, for example no more than 30 minutes. It may be that the or each bather layer is dissolved within 30 minutes. It may be that the barrier layer is dissolved by said solution within 30 minutes at 25°C or above, for example 40°C or above, for example at 60°C. It may be that the barrier layer is dissolved by said solution within 30 minutes at 25°C, at 40°C and/or at 60°C. It may be that the barrier layer is dissolved by said solution within 30 minutes at a temperature of from 25 °C to 90°C inclusive, for example from 40 °C to 60°C inclusive.

It may be that the security paper is exposed to, for example immersed in, a solution having a pH of 8.0 or greater (more basic).

It may be that the security paper is exposed to, for example immersed in, a solution having from 1% (w/w) to 5% (w/w), for example from 1% (w/w) to 2 %, for example 1%, 2% or 5% (w/w), inclusive sodium hydroxide, potassium hydroxide or a mixture thereof It may be that the security paper is exposed to the solution at a temperature of from 22°C to 27°C inclusive, for example at 25°C.

It may be that the security paper is exposed to, for example immersed in, a solution having from 1% (w/w) to 5% (w/w), for example from (w/w) to 2 %, for example 1%, 2% or 5% (w/w), inclusive laundry detergent, for example a Marseille Soap based laundry detergent. It may be that the security paper is exposed to the solution at a temperature of from 40 °C to 90°C, for example from 40 °C to 60°C.

The method comprises dissolving the barrier layer such that the ink of the printed region is separated from the substrate. It will be appreciated that this does not necessarily require 100% of the barrier layer to be dissolved. For example, it may be that the thickness of the barrier layer is reduced across the whole of the area covered by the printed region. That is to say, that a first depth of the barrier layer is dissolved across the whole of the area covered by the printed region. This allows the ink to separate, but some of the barrier layer may remain. Alternatively, it may be that the method comprises entirely dissolving the barrier layer, for example the full depth of the layer above the surface of the substrate.

In a further aspect of the disclosure, there is provided a method of manufacturing an inclusion and/or a security paper in accordance with any other aspect. The method comprises applying a barrier composition to a sheet of paper to form a barrier layer; and then printing with ink on the barrier layer; and then cutting the substrate sheet to produce a plurality of inclusions.

The method may comprise applying a barrier composition to a substrate sheet, for example saturating the substrate sheet with a barrier composition. The substrate sheet may be a sheet of paper.

The method may then comprise printing one or more printed regions on the front and/or back side of the substrate sheet, for example on the or each barrier layer.

The method may then comprise cutting the substrate sheet to produce an inclusion. It may be that the step of cutting, the substrate sheet produces a plurality of inclusions simultaneously, for example with a single cutting motion. Thus, the present methods may be suitable for use in the bulk manufacture of inclusions. Each cutting motion may produce at least 10 inclusions, for example at least 50, for example at least 100 inclusions simultaneously.

The method may comprise cutting the substrate in a cutting pattern. The cutting pattern may comprise a plurality of instances of a shape, for example a geometric shape, for example squares, rectangles, triangles and/or other shapes arranged side by side and/or end to end. The cutting pattern may be a tessellating pattern (i.e. a pattern with no overlaps and/or gaps) of a shape corresponding to the shape of the inclusions, for example a tessellating pattern of squares, rectangles, triangles and/or other shapes. In the case that the cutting pattern comprises a plurality of rectangles, for example arranged side by side and/or end to end, the step of cutting the substrate may provide a plurality of security fibres. In the case that the cutting pattern comprises a plurality of squares, stars and/or circles, for example arranged side by side and/or end to end, the step of cutting the substrate may provide a plurality of planchettes having a corresponding shape.

-12 -The method may further comprise the step of mixing the plurality of inclusions with a pulp and then forming the inclusion-pulp mix into a paper substrate and/or a security paper. The method may comprise mixing the plurality of inclusions with a pulp, for example with a slurry paper pulp such that the inclusions form a hydrogen bond with the cellulose fibre in the paper pulp. The method may comprise forming the pulp and inclusion mix into a continuous web, for example forming the paper pulp and inclusion mix into a continuous web of security paper. The method may comprise recycling the security paper as described above. The method may comprise using the security paper, in the production of a security document, for example in the production of a security device that is affixed to a security document and/or in the production of a security-document substrate for use in a security document.

In further aspects of the disclosure, there is provided a security paper comprises a plurality of inclusions in accordance with any other aspect, and a security document comprising such a security paper.

FIG. 1 shows a plan view of an example fibre 2 in accordance with the present disclosure. The fibre 2 has a front surface 4 with printed regions 6, 8, 10, 12 in the forms of stripes extending across the width of the fibre. In some embodiments, the fibre 2 is 4 mm long and 0.3 mm wide.

FIG. 2 shows a cross-sectional view of a portion of the fibre 2. It will be appreciated that the thickness of the fibre has been exaggerated for the purposes of illustration. In FIG. 2 printed regions 8, 10 are applied on top of a barrier layer 14, the barrier layer 14 extending between the printed regions 8, 10 and the substrate 16 of the fibre. Another barrier layer 15 is located on the other side of the substrate 16, between the substrate 16 and further printed regions 18, 20. Barrier layer 14 is shown as a discrete layer in FIG. 2, but it will be appreciated that the barrier compound may penetrate, for example saturate, the substrate 16. The edges of the printed regions 8, 10 are abutting in FIG. 2, while the printed regions 18, 20 are spaced apart such that the barrier layer 14 is uncovered.

In some embodiments, each printed region 6, 8, 10, 12, 18, 20 is printed with an ink which fluoresces under ultraviolet light to emit visible light, for example each printed region 6, 8, 10, 12, 18, 20 emits visible light of a different colour. In the same or yet further embodiments, it may be that the printed regions 6, 8, 10, 12, 18, 20 are substantially invisible (colourless and transparent) under visible light. In some embodiments, each printed region 6, 8, 10, 12, 18, 20 is printed with an ink that is visible under visible light, for example each printed region 6, 8, 10, 12, 18, 20 appears as a different colour when viewed under visible light.

The fibres are incorporated into a slurry paper pulp that is then formed into a sheet of security paper for use in security documents. When the security paper is immersed in a solution comprising an appropriate active agent, the barrier layer 14 is dissolved, and the ink with which printed regions 6, 8, 10, 12, 18, 20 are printed thereby lifts from the substrate 16. The properties of the paper substrate 16 and the pulp of the security paper are otherwise unaffected. The fibre thereafter has the colour and appearance of the paper substrate 16. The security paper (including the inkless fibres) can then be recycled into a new security paper and the inkless fibres do not impact on the appearance of that new paper.

In one example, the substrate 16 is a cellulose paper, the barrier layer is a Water Based Caustic Soluble Primer MAX 62953 available from Mirage Inks Limited of Frome, UK and the inks are selected from the range of Waterbased Security Inks (Prefix MAX) available from Mirage Inks Limited of Frome, UK, for example MAX61872 (Red).

FIG. 3 shows a flow chart of an example method of recycling a security paper comprising a plurality of inclusions (for example the fibre of FIG. 1 and FIG. 2 or the planchette of FIG. 5), in accordance with the present disclosure. Optional features are shown in dashed-line boxes.

The method comprises exposing 50 the security paper comprising the inclusions to a solution which dissolves 52 the barrier layer such that the ink of the printed regions is separated 54 from the substrate. Optionally, the method then comprises pulping 56 the security paper to produce a pulp, and then adding 58 another set of inclusions (for example an inclusion having a different colour scheme) to the pulp. Optionally, the method then comprises forming 60 the pulp into a recycled security paper. Steps 50 to 60 may be repeated in order to recycle the already-recycled security paper.

The step of exposing 50 the security paper may comprise immersing the security paper in a caustic solution of from 1% (w/w) to 5% (w/w) inclusive sodium -14 -hydroxide, sodium potassium and/or a mix thereof at 25°C, so that the barrier layer dissolves 52 within 30 minutes.

The step of exposing 50 the security paper may comprise immersing the security paper in an aqueous solution of from 1% (w/w) to 5% (w/w) inclusive laundry detergent so that the barrier layer dissolves 52 within 30 minutes.

FIG. 4 shows a flow chart of an example method of manufacturing an inclusion (for example the fibre of FIG. I and FIG. 2 or the planchette of FIG. 5).

The method may comprise applying 80 a barrier layer to a sheet of paper. For example, the method may comprise saturating the paper substrate with a barrier composition. The method may comprise printing 82 with ink on the barrier layer, for example to provide a plurality of printed regions. The method may comprise cutting 84 the paper substrate to produce a plurality of inclusions.

FIG. 5 shows a plan view of a planchette 2 in accordance with a second example embodiment. Like reference numerals denote like elements as between FIG. I and FIG. 5. While the fibre of FIG. I is rectangular when viewed in plan, the planchette of FIG. 5 is circular. The cross-sectional structure of the planchette 2 is as shown in FIG. 2.

FIG. 6 shows a sheet of security paper 90 comprising a security substrate 92 having a plurality of inclusions 2 incorporated therein (the inclusions being shown as dots in FIG. 6).

FIG. 7 shows the results of a test comparing the performance of printed strips with and without a barrier layer. Each strip was immersed in a different solution for 30 minutes and then photographed under UV light. Dashed horizontal lines have been added to FIG. 7 to assist in identifying where each strip begins and ends. A block of ink (Water Based Security Ink MAX61872 (Red) available from Mirage Inks Limited) was printed on a paper substrate suitable for use as a security fibre substrate. A barrier layer (Water Based Caustic Soluble Primer MAX 62953 available from Mirage Inks Limited) had been applied to the substrate, such that a first half of the printed area (the left hand half in FIG. 7) was printed onto the barrier layer, and a second half of the printed area (the right hand half in FIG.7) was printed directly onto the substrate. The different solutions are listed below in Table 1. Percentages are w/w unless otherwise stated. The temperature was 25°C unless otherwise stated.

-15 -Fig. 7 Label Solution $ No test (control) 1 5% Acetic Acid 2 60% Ethanol 3 7% HC1 4 SBP 50% Ethylene Glycol 6 5% Salt Solution 7 10% Sugar Solution 8 5% Sodium Carbonate 9 5% Sodium Hydroxide Acetone HW Hot Water (90°C) LD 2% Laundry Detergent (90°C) 1% 1% Caustic Solution (Potassium Hydroxide) 2% 2% Caustic Solution (Potassium Hydroxide) 3% 3% Caustic Solution (Potassium Hydroxide) The laundry detergent used was Le Chat Paillettes produced by Henkel, which is widely commercially available. Le Chat Paillettes is a laundry detergent based on Marseille soap (Savon de Marseille). The ingredients of Le Chat Paillettes are described as follows on the product information sheet produced by Henkel: * Olive Oil fatty acids, sodium salts (cationic surfactant) * Coconut fatty acids, sodium salts (anionic surfactant) * Water * Sodium Stearate, pure (anionic surfactant) * Sodium Palmitate (anionic surfactant) * Glycerin (solvent) * Sodium Chloride With reference to FIG. 7, for solutions 1, 4, and 7 there was little to no change in the appearance of either half of the block in comparison with the control ($).

For solutions 2, 3 and 10 both the first and second halves of the block experienced a similar change in appearance (the brightness of both halves under UV -16 -somewhat decreased whilst remaining clearly visible) with respect to the control. Without wishing to be bound by theory, it is believed that solutions 2, 3 and 10 are impacting the appearance of the ink itself For solutions 5 and 6, some fainter areas have appeared on the first half of the block (i.e. the side where the barrier is present), while the second half of the block remains unchanged with respect to the control.

For solutions 8, 9, HW, 1%, 2% and 3% there is a significant difference in appearance between the first and second halves of the block. The first half of the block is still visible (just) but is significantly fainter in comparison to the second half of the block, the appearance of which is largely unchanged with respect to the control.

Without wishing to be bound by theory, it is believed that the boundary layer has largely dissolved on the first half of the block, such that the ink is separated from the substrate. It will be apparent to the skilled person that the chemical composition of the barrier layer could be modified and thereby render solutions 8, 9, 1-1W, 1%, 2% and 3% more effective at dissolving the barrier layer within the given time frame. For example, it will be apparent that the chemical composition of the barrier layer could be modified to render solutions 9, 1%, 2% and 3% more effective, and/or the concentration of the active agents in these solutions could be increased to make them effective.

For solution LD, the first half of the block has entirely disappeared. The second half of the block is fainter than the control but still clearly visible. Again, without wishing to be bound by theory, it is believed that the boundary layer on the first half of the block has been dissolved by the LD solution such that the ink is disconnected from and lifts off the substrate. While the LD solution is having some impact on the appearance of the ink itself (given the change in appearance on the second half of the block), it is apparent that the barrier layer greatly facilitates the release of the ink from the substrate. This result appears particularly promising given that the laundry detergent is relatively gentle on the substate, environmentally friendly and low cost.

FIG. 8 shows the results of a test in which samples further investigating the performance of a substrates with and without a laundry detergent soluble barrier layer. Blocks of different inks (from left to right, Water Based Security Inks MAX61577 (Green), MAX61872 (Red), MAX62438 (Orange Match), available from Mirage Inks -17 -Limited) were printed on a paper substrate suitable for use as a security fibre substrate. A barrier layer (Water Based Caustic Soluble Primer MAX 62953 available from Mirage Inks Limited) had been applied along a central region of the substrate, such that a central region of each block was printed on top of the barrier layer, with regions either side of that central region being printed directed onto the substrate.

Strips were immersed in different solutions as summarised in Table 2 below.

Fig. 8 Label Solution 1 room temperature water 2 60°C water 3 2% laundry detergent (Le Chat Paillettes) in 60 °C water Strips were removed from the solution and photographed under UV light after 30 minutes. For the avoidance of doubt, strips were not returned to the solution after they had been removed i.e. a different strip is being photographed at each time interval. For each solution 1 to 3, FIG. 8 shows the appearance of a strip after 30 minutes, 1 hour, 1 hour 30 minutes, 3 hours and 6 hours. Immersion in solution 1 (room temperature water) does not gives rise to a change in appearance in any of the images shown in FIG. 8. That is to say, room temperature water does not appear to impact the ink, or dissolve the barrier layer, over a period of six hours. After immersion in solution 3 (2% laundry detergent in 60% water) for 30 minutes the central section (i.e. the region printed on the barrier layer) is significantly fainter for all three ink blocks. For each of the three inks, the central section is fainter than the regions either side (i.e. without the barrier layer). The regions of the second ink block (MAX61872 (Red)) that are printed directly onto the substrate are fainter after 30 minutes in solution 3, as compared to their appearance after 30 minutes in solution 1, but they are still clearly visible and much brighter than the central region. After 6 hours in solution 3, the regions that are printed directly on the substrate are all still visible. Without wishing to be bound by theory, it appears that solution 3 rapidly dissolves the barrier layer allowing all the inks tested to lift off the substrate. After immersion in solution 2 for 30 minutes, there are some fainter patches in the regions printed on the barrier layer, but there is still a significant amount of ink present in those regions after 6 hours. There was significant variability in appearance in the ink blocks in solution 2. Thus, while temperature does appear to have some effect, it -18 -appears the laundry detergent is playing an important role in dissolving the barrier layer. Without wishing to be bound by theory, it is believed that the glycerin and/or vegetable oils in the Marseille Soap are dissolving the barrier layer.

Whilst the present disclosure has been described and illustrated with reference to particular embodiments, it will be appreciated by those of ordinary skill in the art that the disclosure lends itself to many different variations not specifically illustrated herein.

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. Reference should be made to the claims for determining the true scope of the present disclosure, 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 disclosure that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, whilst of possible benefit in some embodiments of the disclosure, may not be desirable, and may therefore be absent, in other embodiments.

Claims (23)

1. -19 -Claims 1. A method of recycling security paper comprising a paper substrate having a first set of inclusions incorporated therein, wherein each inclusion of the first set comprises a substrate, a printed region and a barrier layer between the substrate and the printed region, the method comprising: exposing the security paper to a solution which dissolves the barrier layer of the inclusions such that the ink of the printed region is separated from the inclusion.
2. 2. A method according to claim 1, further comprising, after the ink is separated from the substrate of each of the first set of inclusions; pulping the security paper to produce a pulp; and then adding a second set of inclusions to the pulp, wherein each inclusion of the second set comprises a substrate and a printed region; and then forming the pulp having the first and second sets of inclusions incorporated therein into security paper.
3. 3. A method according to claim 1 or claim 2, wherein the solution comprises water and an active agent and the layer is dissolved by the solution within 30 minutes at 25 °C or above, for example at 40°C or above, for example at 60°C, and wherein the barrier layer is not dissolved by water alone under the same conditions.
4. 4. A method according to any previous claim, wherein the security paper is exposed to a solution having from 1% (w/w) to 5% (w/w) inclusive laundry detergent at a temperature of from 25 °C to 90°C inclusive, for example from 40 °C to 60°C, inclusive for 30 minutes thereby dissolving the barrier layer.
5. 5. A method according to claim 4, wherein the laundry detergent is a Marseille-soap based laundry detergent, for example wherein the comprises, consists essentially of, and/or consists of Marseille Soap.
6. 6. A method according to any previous claim, wherein the security paper is exposed to a solution having from 1% (w/w) to 5% (w/w) inclusive sodium -20 -hydroxide, potassium hydroxide or a mixture thereof at from 22°C to 27°C inclusive, for example at 25°C, for 30 minutes thereby dissolving the bather layer.
7. 7. A method of manufacturing an inclusion for use in a security paper, the method comprising applying a barrier composition to a sheet of paper to form a barrier layer; and then printing with ink on the barrier layer; and then cutting the substrate sheet to produce a plurality of inclusions.
8. 8. An inclusion for use in a security paper, the inclusion comprising: a substrate; a printed region; and a barrier layer between the substrate and the printed region such that when the barrier layer is dissolved the ink of the printed region is separated from the inclusion.
9. 9. An inclusion according to claim 8, wherein the barrier layer is dissolved by a solution comprising water and an active agent within 30 minutes at 25°C or above, for example 40°C or above, for example at 60°C, and wherein the barrier layer is not dissolved by water alone under the same conditions and within 30 minutes.
10. 10. An inclusion according to any of claims 8 or 9, wherein the barrier layer dissolves in a solution having from 5% (w/w) to 1% (w/w) inclusive laundry detergent within 30 minutes at 40°C or above, for example at 60°C.
11. 11. An inclusion according to any of claims 8 to 10, wherein the barrier layer dissolves in a solution having from 5% (w/w) to 1% (w/w) inclusive sodium hydroxide, potassium hydroxide or a mixture thereof, within 30 minutes at 25°C.
12. 12. An inclusion according to any of claims 8 to 11, wherein the substrate is made of a cellulose material, for example wherein the substrate is paper.
13. 13. An inclusion according to any of claims 8 to 12, comprising a barrier layer between the substrate and all the printed region(s) of the inclusion.
14. -21 - 14. An inclusion according to any of claims 8 to 13, wherein the substrate has a front face, the barrier layer is on the same side of the substrate as the front face, and the barrier layer extends over the majority of, for example the whole of, the front face.
15. 15. An inclusion according to any of claims 8 to 14, wherein the inclusion comprises first printed regions and second printed regions, and the barrier layer is between the first printed regions and the second printed regions on one side, and the substrate on the other.
16. 16. An inclusion according to claim 15, wherein the inclusion comprises further printed regions, and each printed region is a stripe extending across the substrate, and the printed regions form a repeating pattern along the length or diameter of the substrate.
17. 17. An inclusion according to any of claims 8 to 16, wherein the barrier composition is present throughout the majority of, for example substantially the whole of, the volume of the substrate.
18. 18. An inclusion according to any of claims 8 to 17, wherein each inclusion is a fibre or a planchette.
19. 19. A security paper comprising a paper substrate having a plurality of inclusions according to any of claims 8 to 18 integrated therein.
20. 20. A security paper according to claim 19, wherein the substrate of each inclusion has substantially the same visible appearance, for example the same colour under visible light, as the paper substrate.
21. 21. A security paper according to claim 19 or claim 20, comprising a first set of inclusions, each inclusion of the first set comprising a substrate, but not including any barrier layer and not including any ink layer; and a second set of inclusions, wherein each inclusion of the second set is an inclusion according to any of claims 8 to 18.
22. -22 - 22. A security paper according to any of claims 19 to 21, wherein the paper substrate is made of a cellulose material, for example wherein the paper substrate is made of the same material as the substrate of the inclusions.
23. 23. A security document comprising a security paper in accordance with any of claims 19 to 22