ES2432189T3 - Safety fibers - Google Patents

Abstract

A security fiber for use in counterfeit protection, the security fiber being suitable for incorporation into a paper product, the security fiber having a paper sheet or cellulose-based substrate form and comprising a colored area, in which the colored zone is composed of a series of different colors, CHARACTERIZED BECAUSE the safety fiber also comprises a first margin and a second margin, the margins being non-printed areas adjacent to the colored zone, so that the colored zone is located between the first and the second margins

Description

Security fibers

The present invention relates to security fibers for use in security papers with counterfeit protection. In particular, the invention relates to security fibers having a series of colored fluorescent bands or zones. The invention also relates to a method for manufacturing said fibers, and to paper products incorporating said fibers. It is well known to provide security paper products, such as banknotes, checks, passports, identity documents and fiduciary papers, with some kind of

10 protection against forgery. Counterfeit protection measures may include watermarks, holograms, the arrangement of one or more metal bands through the paper, the use of fluorescent particles and the use of optically variable coatings and inks. Problems with known counterfeit protection measures include the costs of some measures and the ease with which some measures can be overcome, for example using methods that include digital and laser printing,

15 scanning, photography and xerography.

Another example of a security feature that is incorporated into a security paper is a security fiber.

20 The paper is made of paper pulp, which contains cellulose fibers, for example threads of wood, hemp, straw and cotton (it should be noted that, although cellulose fibers are used to make paper, they themselves are not composed of paper). A known safety technique is to replace, with artificial fibers made of materials such as polyester, nylon and rayon, some of the cellulose fibers used to make a security paper. A relatively small amount of artificial fibers may be included in the paper pulp, together with

A majority of cellulose fibers, which results in the security paper being made of a pulp having artificial fibers incorporated therein and distributed randomly. Artificial fibers can be dyed or coated, which results in the paper including a random pattern of small colored areas. The dye can be one sensitive to ultraviolet (UV) light, so that the randomized colored pattern is visible only under UV light.

Such artificial fibers are generally fibrous (ie predominantly one-dimensional rather than two-dimensional or sheet-like), such as the cellulose fibers they replace. WO2004 / 025028 (D W Spinks (Embossing) Ltd) describes security features that are referred to as "fibers" because they replace them, and bind to the cellulose fibers used in the manufacture of security paper, and

35 because, in the manufactured paper, they provide a visual appearance that suggests that they are similar to such fibers. However, the paper fibers described in said document are small bands of paper, and have no fibrous shape.

Therefore, security fibers can be added in the form of small paper strips (e.g.

40 approximately 4 mm x 0.3 mm) to the paper pulp during manufacturing and be incorporated into the paper sheets that are manufactured. Security fibers are often invisible in daylight and remain hidden from the naked eye. However, when they are irradiated with ultraviolet light they become fluorescent and visible on the sheet of paper.

45 Monochrome fibers are relatively simple and economical to manufacture. However, counterfeiters have been able to use highlighter-type fluorescent marker pencils to simulate monochrome fibers on a sheet of paper. Invisible fluorescent inks are increasingly available, and the ease of the forgery process, by making a few strokes on a sheet of paper, is reducing the effectiveness of monochrome fibers as a safety device.

50 One solution is to manufacture security fibers that comprise zones of different colors, which increases the difficulty and cost of manufacturing counterfeit fibers. Such security fibers are described in detail in WO2004 / 025028 A1. "Fibers" are intended for incorporation into paper products, as a counterfeit protection class. Each fiber has a series of colored areas visible on the front and

55 of said fiber, in which the colors are visible only under UV light. The zones may be in the form of bands, or they may be arranged in a pseudorandom pattern. The zones may be colored differently. Security fibers become much more difficult to simulate if the different color zones are printed with a specific color sequence, for example, the colors of a traditional flag.

Such security fibers are very small, for example, approximately 4 mm x 0.3 mm, since it has been found that the major fibers or other major types of security elements are difficult to incorporate into the paper and easily removed. This can be a major problem when printing banknotes, which undergo various printing processes using high pressure and high adhesion inks. Fibers of

5 higher security can be accidentally removed during the printing process, which causes the paper to be rejected.

Making a small fiber of this type with different color zones, in particular different color zones with differentiated color combinations recorded with all other small manufactured fibers and with the same pattern as them is an extremely difficult process. In the existing process, the pattern is printed on a large surface of material and then the small fibers are cut from said large surface; however, it is difficult to cut the fibers with a perfect record. Existing methods of large-scale material cutting do not provide a means to register printing with the cutter, and many fibers are manufactured that do not have the colors registered with each other. Existing methods do not allow cutting to be controlled in a manner consistent with

A tolerance between 0.125 mm and 0.25 mm, which is considered to be the maximum tolerance for the colors in said fiber to appear the same size and position.

The present invention seeks to mitigate or overcome one or more of the previously identified disadvantages associated with the prior art.

The invention provides a security fiber for use in counterfeit protection, the security fiber having the characteristics indicated below in claim 1. Preferred features of the invention are indicated in the dependent claims.

25 The margin is an unprinted area of the security fiber, that is, an area that lacks printing, which provides greater adhesion when incorporated as a security fiber in a paper product, than a security fiber without An unprinted area.

The colored area of the security fiber may include a varnish to make the colored area impervious to

30 water, or hydrophobic. Advantageously, this prevents the colored area from degrading when the security fiber is being mixed with paper pulp or in a subsequent printing process. The varnish can increase the abrasion resistance of the colored area of the safety fiber. However, such a varnish can reduce the adhesion of the colored area of the security fiber with the paper product in which it is to be embedded. Advantageously, the margin is not printed, and / or is porous, which increases the adhesion between the fiber of

35 paper and the paper product in which it is incorporated. The colored area can be visible only under ultraviolet light. Preferably, the colored area is fluorescent under ultraviolet light. Providing a colored area that is visible only under ultraviolet light allows protection against forgery whose incorporation into the paper is not visible to the naked eye.

40 Preferably, the margin does not contain visible marks under ultraviolet light.

Advantageously, the margin or margins adjacent to the colored zone act to provide a margin of error when the fiber is manufactured. The security fiber can be cut from a substrate, for example a sheet of paper, so that the cutting takes place at the margin or margins. Therefore, a certain level of

45 inaccuracy during the cutting process, since it no longer affects the appearance of the colored area, which will continue to appear to be in perfect register.

The colored area can be printed on both sides, front and back, of the security fiber. The security fiber can be printed on both sides, front and back, printing on one of said front sides or

50 and allowing the ink to soak or bleed through the other side of the security fiber. Alternatively, the security fiber can be printed on its two front and rear sides, printing on one side of the security fiber and then printing on the other side of the security fiber.

The margin or margins may be transparent. The security fiber can be printed on paper, which can

55 be a transparent paper. When transparent paper is used, the colored area may be printed only on one side of the paper, but visible through the paper from the other side. The paper can be made transparent by applying a varnish; in this way a varnish can be applied to the paper, and then the colored area can be printed on the varnish. Alternatively, the security fiber can be printed on a cellulose based substrate. The material on which the security fiber is printed may not have background fluorescence. The margin or margins may completely surround the first colored zone. The margin

or margins may extend from 0.5 mm to 5 mm from the edges of the colored area to which they are adjacent.

The fiber can be a sheet of paper. The paper can have a weight between 10 gr and 75 gr. Preferably, the

5 paper has a weight of between 10 gr and 35 gr; according to the American Paper Weights and Measures standards, tissue paper has a weight of between 10 grams and 35 grams, and therefore the sheet can be a sheet of tissue paper. It is possible that the paper has a wet tensile strength of at least 1 N / 15mm, more preferably at least 3 N / 15mm. The paper may have a wet tensile strength of less than 15 N / 15mm, preferably less than 7 N / 15mm. (The wet tensile strength can be the

10 wet tensile strength of the paper itself, or it can be the wet tensile strength of the paper including any printing, varnishes or other material that increases the wet tensile strength with respect to that of the paper itself.) Paper can have a dry tensile strength of approximately 5 daN / 30mm. The paper may have an opacity of up to 90% or greater, or alternatively it may be transparent. The paper may include a varnish.

15 The colored area may comprise a series of bands of different color. These can be two, three, four or more bands in the first zone, colored. Said band zones may include, for example, any or all of the colors red, green, yellow and blue. The bands can be placed in graduations of approximately 1 mm. Bands can be presented in the same order, that is, in a repetitive pattern.

20 Advantageously, presenting the bands in the same order in a repetitive pattern makes it more difficult to counterfeit the paper fiber. The colored area may have a rectangular shape. The colored zone can measure between 3 mm and 5 mm in length, and between 0.2 mm and 1 mm in width. The colored zone may comprise a more complex pattern than the bands. For example, the colored zone can be a two-dimensional pattern. The colored area may include an image of a flag, and / or a combination of numbers and / or letters or some other recognizable image.

25 The margin or margins may extend from 0.5 mm to 2 mm from the edge of the colored area to which they are adjacent. It is possible that the security fiber is between 3.5 mm and 9 mm long. It is possible that the security fiber is between 0.2 mm and 6 mm wide. Preferably, the colored area is located approximately in the center of the paper fiber, with the first and second margins located at each end.

30 of the paper fiber.

Preferably, the security fiber is a security fiber of 5 mm, 6 mm or 7 mm in length with a first colored zone of 3 mm, 4 mm or 5 mm respectively. However, it is clear that the invention can be applied so that a longer or wider security fiber is manufactured, although the fibers

Overly long ones are not desirable, since they can be "removed" from the security paper. The dimensions of the colored area and the margin or margins can be correspondingly increased proportionally.

The invention also discloses a method of manufacturing a security fiber for use in counterfeit protection, the security fiber being suitable for incorporation into a paper product,

The method comprising the steps indicated below in claim 8. Advantageously, the substrate on which the colored areas are printed lacks background fluorescence under ultraviolet light.

Advantageously, the margins increase the margin of error allowed during the cutting process without affecting the appearance of the colored areas.

45 Preferably, the colored areas are visible only under ultraviolet light.

Preferably, the method includes the step of cutting the substrate to create a series of security fibers. The series of colored areas can be printed on the substrate in a series of rows. Each colored zone can

50 understand a series of colors printed in juxtaposition. This series of colors can be printed to form bands. There may be two, three or four bands printed in each colored area. The bands may include any or all of the colors red, green, yellow and blue. Such a series of colors can be printed to form a more complex pattern than the bands. The colored zone may comprise a more complex pattern than the bands. For example, the colored zone can be a two-dimensional pattern. The colored zone may include a

55 image of a flag, and / or a combination of numbers and / or letters or some other recognizable image.

Each colored zone is located between two margins, which are unprinted areas of the substrate. The printing of the series of colored areas in this way, can create a wavy effect due to the increased level of the colored areas once the ink has been printed on the substrate, so that when a piece of substrate

printed in this way is stacked on another piece of substrate printed in this way, the sheets settle in a natural alignment. Preferably, several sheets of substrate are stacked on top of each other and cut simultaneously. The stack of substrate sheets to be cut can be between 10 mm and 20 mm high. The natural alignment of the substrate sheets, together with the cutting that takes place within the margins, allow the cutting process to deviate, for example, up to 1 mm without any consequence on the appearance of the colored area of the paper fiber For example, the colored area may appear to be 4 mm long and in the correct proportion of red, green, yellow and blue, regardless of the variation in the cut of the security fiber. The cutting process may also include the substrate being cut so that the colored areas are cut perpendicular to the cuts made along the margins. Since these cuts are

10 through the colored zone, the color sequence of any bands or patterns included in the colored zones are not affected due to any cutting inaccuracies. The cuts can produce, for example, a paper fiber with a length between 3.5 mm and 9 mm, and a width between 0.1 and 0.5 mm.

The cuts can be made with a specially developed blade, the blade being arranged so

15 that can cut the substrate at least in a margin and also through the colored area, simultaneously. Preferably, the blade is arranged to be able to cut the substrate with a single cut for the purpose of manufacturing the security fibers. Preferably, the blade comprises a crenellated blade.

The method may include the step of printing the colored areas on both front and back sides of the substrate. The

The step of printing the colored areas on both front and back sides of the substrate may include printing the substrate on one of its front or back sides, and allowing the ink to soak through the other side of the substrate. Alternatively, the step of printing the colored areas on both front and back sides of the substrate may include printing on one side of the substrate, and then printing on the other side of the substrate.

25 The substrate may comprise paper. Alternatively, the substrate may comprise a cellulose based substrate.

The present invention also discloses a method of manufacturing a paper product, in which the method comprises the steps of mixing with liquid pulp a series of the described security fibers

30 above, so that the security fibers form a hydrogen bond with the cellulose fiber of the paper pulp, and form the mixture of paper pulp and security fibers in 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 is a schematic drawing of an example of a sheet of printed paper according to an embodiment of the invention;

Figures 2a and 2b are a schematic drawing of an example of the security fibers according to an embodiment of the invention;

Fig. 3 is a schematic view of an exemplary security paper, in accordance with an embodiment of the invention, illuminated by (a) visible light; and (b) UV light;

Figure 4 is a flow chart showing steps in the manufacturing of the exemplary safety fiber of Figure 2;

Figure 5 is a flow chart showing steps in the manufacture of the exemplary security paper of Figure 3; Y

Figure 6 is a schematic drawing of an example of a blade used to cut the security fibers.

Figure 1 shows a piece of substrate (1), on which a series of colored areas (2) have been printed.

55 Colored areas (2) are visible only when viewed under ultraviolet light. The colored areas are generally rectangular in shape and consist of four bands of different colors, (21), (22), (23) and (24), printed in juxtaposition. The four different colors (21), (22), (23) and (24) are fluorescent colors and are visible only under ultraviolet light. The colors in this example are red, green, yellow and blue. In one embodiment, colors are visible when irradiated in the ultraviolet light fiber with a wavelength between 245 nm and 365 nm. In any specific embodiment and for any specific color, the wavelengths at which the colors are visible depend, of course, on the pigments used to generate the prints.

In this embodiment of the invention, both sides of the substrate (1) are printed with the colored areas (2). In this

5 case, the substrate (1) is a thin and porous paper and printing on a single side of the substrate (1) with an adequate amount of ink assumes that the ink soaks through the substrate (1) and, therefore, both sides of the substrate have been printed (1). In an alternative embodiment, each side of the substrate (1) is printed individually, so that the colored areas (2) on each side of the paper are aligned registered with each other.

10 Figure 1 shows three colored zones (2) interested in the substrate (1). Adjacent to the colored zones (2), and separating the colored zones (2) from each other, there are a number of margins (3) that are not fluorescent under ultraviolet light. In this case, the margins (3) are areas of the substrate (1) that have not been printed. The printing of the colored areas (2) and the non-printing of the margins (3) creates a slight waving effect because the printed areas are slightly elevated compared to the non-printed areas. Waving effect

15 can advantageously be used when several sheets of similarly printed substrate (1) are stacked, which puts the substrate sheets (1) in natural alignment with each other. The cutting of the substrate (1) can then be carried out advantageously with several sheets of substrate on one another, thus saving time and effort.

Figure 1 also shows, with dashed lines, the planned cut lines (4). In figure 1, they are shown

20 only the cutting lines parallel to the margins, to better demonstrate the advantages of the invention. Figure 6 shows the cutting contour of a blade that is designed to cut the substrate (1) so that a single cutting stage can produce rectangular security fibers. The blade comprises a blade with a crenellated cutting edge. The size of the crenellated corresponds to the size of the security fibers. The blade is lowered onto the stack of substrate sheets, thereby cutting a series of safety fibers

25 rectangular The blade blade sections that are designed to cut along the cutting lines (4) are shown as parts (41), and the blade blade sections that cut through the colored areas ( 2) are marked as (42). The blade or substrate sheets are then moved (in the direction parallel to the length of each band (21), (22), (23), (24), that is, up or down on the page of the Figure 1) and another cut is made, thus creating more security fibers.

30 Due to the margins (4) located between the colored areas (2), minor deviations from the cut can be tolerated with respect to the planned cut lines (4), without affecting the shape, size and appearance of the colored areas ( 2).

The substrate (1) from which the security fibers are manufactured in the embodiment of the invention described above, is a thin fabric or paper without optical brighteners. The optimal paper is a tissue paper of high porosity and high wet strength, with a nominal weight of 25 grams per square meter. The composition of the paper is important because the ability to print and cut a thin substrate provides a technical barrier for fiber duplication.

Fibers have been manufactured in accordance with the present invention using paper with the properties listed below. These properties have been developed with the intention of making known a fiber that works well, but they are only an example. Other papers could be used.

Properties

Units Minimum Maximum Average

Substance

g / m2 fifteen Four. Five 24.8

Lemm

mm 16 17 16.6

Capillarity increase md

Wet tensile strength

N / 15mm 4,5 5.9 5.14

Volume

Cm3 / g 2.4 2.5 2.46

High porosity

1 / mn / 100cm2 24 31.2 27.9

Moisture pH of aqueous extract

% 4.9 7.0 6.8

In addition, the porosity of the target Bensten (defined by the ISO 5636/3 standard) is 1500ml / mm, and the minimum Bensten value is 700 ml / mm.

5 As described for the embodiment of the invention shown in Figure 1, four different color bands are printed in the colored areas (2). Products suitable for the printing process have been developed, from commercially available pigments. Each of the red, green, yellow and blue prints has a Blue Wool light resistance of 3, an excitation wavelength in the region of 365 nm and

10 good chemical resistance.

The colored areas (2) can also be coated with a varnish. The varnish protects the colored areas (2) against abrasion and also improves the affinity of the fibers in the finished paper. In one embodiment, the varnish is a 4% solution of Solvitose NX in an acrylic water binder.

Figure 2a shows a paper fiber (51) that has been cut according to the planned cut lines (4) (and also, in the direction perpendicular to the cut lines (4) described above, is has manufactured said thin security fiber, approximately rectangular). The security fiber (51) is approximately 5mm x 0.3mm, the colored areas being approximately 3mm in length. The zones

20 colored (2) are approximately in the center of the paper fiber (51), located between two margins (31) and

(32) of equal dimensions. The margins (31) and (32) are approximately 1 mm long each. Figure 2b shows a safety fiber (52), approximately with the same dimensions as the security fiber (51), which has been cut with a deviation from the planned cutting lines (4), due to the tolerances of the cutting machine. The colored area (2) is located on the left side of the paper fiber (52),

25 as seen in the figure. The colored zone (2) is located between two margins (33) and (34), although the margin (33) is smaller than the margin (34). However, despite the inaccuracy of the cutting process, when viewed under ultraviolet light, the colored areas of the security fiber (51) and the security fiber (52) will appear identical.

The fibers (51), (52) are incorporated in the paper pulp used to make a security paper, in this

30 example a banknote (50) (figure 3). Under visible light (Figure 3 (a)), the fibers (51), (52) are invaluable, mixing with other cellulose fibers, which make up the paper of the banknote (50). However, under long wavelength UV light, the fibers (51), (52) are fluorescent, forming a random pattern of multicolored marks on the banknote (50) (shown schematically, to facilitate illustration, by means of dotted pattern of figure 3 (b)). Therefore, UV light is used to check the validity of the security paper, by

35 example, in a store, or through a bank teller.

The fibers (51), (52) are manufactured by the process shown in Figure 4. The paper is removed from a roll in a paper store (60) and passed to a printing machine (70). The printing machine (70) includes ink tanks (80) (a) through (d), which contain four inks containing pigments that are fluorescent in different

40 colors when illuminated with UV light. The printing machine prints on the zones (21), (22), (23), (24) to form multiple copies through the paper substrate (1). The printed paper substrates pass to the cutting machine (90), where they are cut into fibers (51), (52). The cut fibers (51), (52) are deposited in a container

(100) for transport to a paper mill.

In the paper mill, the banknote of Figure 3 is manufactured by the method shown in Figure 5. The security fibers (51), (52) manufactured by the method of Figure 4 are removed from the warehouse ( 110) and mixed with water and conventional cellulose fibers (from a second store (120)) to form a paste (130). A papermaking machine (140) manufactures paper from the pulp (130), using conventional methods. In step 150, additional paper processing takes place, which includes the

5 printing of standard and similar images. Next, the manufactured and printed paper is cut (step (160)) to form the paper product (170), in this case, banknotes.

Therefore, paper products according to the present invention are manufactured by mixing liquid paper pulp with the security fibers of the present invention. The security fibers of the present invention form

10 a hydrogen bond with the cellulose fibers in the paper pulp, and when the pulp is formed in a continuous paper web, the pulp security fibers become an integral part of the paper web. Colored areas of the fibers can only be seen under ultraviolet light, thereby providing a safety feature that cannot be seen in normal light conditions.

In the above description, when integers or elements having known, obvious or predictable equivalents are mentioned, said equivalents are incorporated herein as if they had been defined individually. For example, the substrate can be a cellulose or plastic based material. The colored zone may comprise a more complex pattern than the bands, for example, a two-dimensional pattern or a combination of numbers and / or letters. The colored area can be a representation of a flag or other image

20 recognizable.

Reference should be made to the claims to determine the true scope of the present invention, which should be conceived to encompass any of its equivalents. The reader will also appreciate that whole numbers

or the features of the invention that are described as preferable, advantageous, convenient or similar, are optional and do not limit the scope of the independent claims.

Claims (13)

1. A security fiber for use in counterfeit protection, the security fiber being suitable for incorporation into a paper product, the security fiber having a sheet of paper or 5 of cellulose-based substrate and comprising a colored zone, in which the colored zone is composed of a series of different colors, CHARACTERIZED BECAUSE the security fiber also comprises a first margin and a second margin, the margins being adjacent unprinted areas to the colored zone, so that the colored zone is located between the first and second margins. A security fiber according to claim 1, wherein the colored area is visible only under ultraviolet light. 3. A security fiber according to claim 1 or claim 2, wherein the margin is not visible under ultraviolet light. fifteen 4. A security fiber according to any preceding claim, comprising a transparent substrate. 5. A security fiber according to any preceding claim, wherein the security fiber 20 is between 3.5mm and 9mm in length, and between 0.2mm and 6mm in width. A security fiber according to any one of claims 1 to 5, wherein the colored zone is located approximately in the center of the security fiber, with the first margin and the second margin located at respective ends of the fiber of security.

7.

A security fiber according to any preceding claim, further comprising a layer of varnish on at least the colored area.

8.

A method of manufacturing a safety fiber for use in protection against

Forgery, the security fiber being suitable for incorporation into a paper product, the method comprising the steps of printing a series of colored areas on a substrate in the form of a sheet of paper or a cellulose-based substrate, and cutting the substrate to create a security fiber that includes at least one of said colored areas, CHARACTERIZED BECAUSE each of said series of colored areas is located between a first and a second margin, the unprinted areas of the substrate margins adjacent to 35 the colored area, the substrate being cut in the margins. 9. A method according to claim 8, the method including the step of cutting the substrate into a series of margins to create a series of paper fibers. A method according to claim 9, wherein the series of colored areas are printed on the substrate in a series of rows. 11. A method according to claim 9 or claim 10, wherein each colored zone It comprises a series of colors printed in juxtaposition. Four. Five 12. A method according to any of claims 8 to 11, which includes an additional step of stacking at least one substrate on another, identical substrate, and simultaneously cutting the substrates. 13. A method according to any of claims 8 to 12, which further includes a step of cutting the substrate in a direction perpendicular to the cuts made in the margin. 14. A method of manufacturing a paper product, the method comprising the steps of: mixing one or more security fibers according to any one of claims 1 to 7 or one or more 55 security fibers made using the method of any of claims 8 to 13, with liquid paper pulp, such that the security fibers form a hydrogen bond with the cellulose fiber in the paper pulp; and form the mixture of paper pulp and fiber in a continuous band of paper. 15. A paper product containing a series of security fibers in accordance with any of the claims 1 to 7, or manufactured using the method of any of claims 8 to 13.