MXPA06004739A - Cardboard and a method of manufacture thereof - Google Patents

Abstract

The invention relates to cardboard used in authenticity products, comprising a fibre matrix having two surfaces, whereby the second surface of the fibre layer has a layer of surface sizing containing a marking agent in a particle form, its particle size being smaller than 50µm. By incorporating the marking agent into the surface sizing, the particles of the marking agent can be attached to the board, at the same time decreasing their total consumption by 80 to 90%compared with a case where they would be added to pulp. By using particles of a size less than 50µm, a top free from seaks and roughness can be formed, which streaks might otherwise weaken the quality of the product.

Description

CARDBOARD AND A METHOD OF ELABORATION OF THE SAME The present invention relates to paperboard according to the preamble of Claim 1. In general, this kind of cardboard, which is intended to be used in products of authenticity in particular, comprises a fiber binder having two surfaces, of which at least one is provided with a surface sizing layer. The invention also relates to the method according to the preamble of Claim 22 for the production of cardboard proposed for products of authenticity. Security markings are used to indicate and identify the authenticity of products. An example of a traditional security marking is the watermark, which comprises a pattern of printing made on the paper surface. The purpose of watermarking is to indicate the origin of the paper. Wraps and packs are provided with seals and projections to ensure the integrity of the product. Recently, hologram patterns, security lines and similar brands have also been integrated into banknotes in order to complicate the falsification of banknotes. These safety markings have also been integrated into product packaging, such as plastic compact disc wraps. Electronic safety markings include micro circuits and induction coils that contain information in an electrical form, which can be used to identify and confirm the origin of the product. In this invention, a product provided a security mark also called a "product of authenticity". A disadvantage of many modern authenticity products is that the security markings, which are the most difficult to forge, are manufactured separately, whereby a separate operation step takes the joining of the product and the security marking. This concerns paper and cardboard products, such as wrapping and product packaging boxes in particular. In addition, it is difficult to attach to them, for example, a safety marking made of plastic that could be detached relatively unknowingly. Any marking agent required for security markings can be incorporated into packaging board by mixing it with the pulp in the cardboard machine. In that case, the marking agent can be evenly distributed in the fiber binder of the paperboard. However, there is a problem as the consumption of marking agent becomes quite high, because only a fraction, typically 10 to 70%, sometimes only 10 to 40% of the marking agent particles is visible, when The surface of the cardboard is examined. The rest remains under other particles and fibers, when the cardboard is examined or analyzed perpendicular to the surface. Another significant problem is that some of the marking agent is directed to the circulating water of the cardboard machine, contaminating all the devices and pipes that are in contact with the short circulation water and the long circulation water. The purpose of the present invention is to provide a novel solution for the manufacture of cardboard, suitable for products of authenticity, such as packaging. The purpose of the invention is to provide, in particular, a new cardboard product, the processing of which allows a simultaneous decrease in the consumption of marking agent and the contamination of circulating water. The basic idea of the invention is to introduce the marking agent to the cardboard in a mixture with the sizing. A product of authenticity having fluorescent particles intermixed with the binder distributed over its surface is known from the publication of EU 2002/0066543. In this solution, the brand is distributed over the product, for example, by painting, diffusion by roller, spray, conventional printing methods or with a marking pen. The method is applicable to safety marking of relatively small surfaces. However, it is not easily applicable, or at least economic, if the authenticity marking is desired to be introduced on large uniform surfaces. US Patent 6060426 discloses a thermal paper, which is provided with an almost infrared fluorescent compound to complicate the falsification of the paper. In the publication Fl 864951 a paper is described, which incorporates pigment in the form of grains.

However, due to its rigidity, the products disclosed in these publications are not suitable for packaging materials, for example. One kind of a solution for implementing a safety marking for paper is also given in the publication of WO 03/057785, in a method according to which the marking agent is impregnated in the paper by the use of vegetable oils. However, in a safety marking implemented by impregnation, the consumption of the marking agent is not economically high, since only part of the impregnated marking agent is visible, when the surface of the product is observed. The present invention removes the deficiencies. of the methods and products according to the publications mentioned above. According to the invention, the marking agent is incorporated in the surface bonding layer of the fiber binder, in particular, it is incorporated in the surface sizing of the surface on the reverse side of the fiber binder. In that case, the particles of the marking agent are distributed over the fiber binder together with the sizing mixture; whereby, in order to provide a layer of a smooth and flawless surface, a particle marking agent having a sufficiently small particle size is used so as not to form a non-uniform surface after diffusion . In connection with the invention, it was established that the average particle size of the marking agent should be substantially less than 50 μm, whereby 5% at the most, preferably 0.01-4% and typically about 1-2% of the particles have a particle size greater than 50 μm. The invention also provides a method for making cardboard used in authenticity products, according to which method a surface sizing layer is diffused onto the other surface of the fiber binder of the paperboard, the surface forming the reverse side of the paperboard, the layer of surface sizing a labeling agent mixed therewith, comprising particles of less than 50 μm, as defined above. The surface glued reverse side is preferably left uncovered. The surface forming the surface layer of the fiber binder can be left free of surface sizing or a surface sizing that does not contain the marking agent that diffuses thereon. To be more precise, the cardboard according to the invention is characterized in that which is presented in the characterization part of Claim 1, The method according to the invention is characterized in that which is presented in the characterization part of the invention. Claim 22. The invention provides considerable advantages. According to the above, by including the marking agent in the surface sizing, the particles of the marking agent can be attached to the cardboard, whereby the total consumption thereof decreases by 80 to 90% compared to a case in which they would be added to the pulp. When using particles with a size of less than 50 μm, an upper part can be formed, which is free of streaks and irregularities, which could otherwise decrease the quality of the product. The method of preparation according to the invention is advantageous in many aspects. According to the above, by not including the marking agent in the cardboard until the surface sizing step, the particles can be prevented from entering the circulating water of the cardboard machine. This reduces the need to clean the cardboard machine and its peripherals. The special quality packaging board is made from conventional paperboard by introducing the marking agent in the surface gluing step of the paperboard, whereby the production costs are reduced. At the same time, a change can be made flexibly from the production of special quality packaging board with respect to ordinary cardboard after the press is glued. It is also possible to produce different products for different customers by changing the marking agent included in the surface sizing layer. The cardboard provided by the invention is, for example, in the form of a channel, lamp, graphic product, packaging or a form of a package.

The other advantages and features of the invention are described in the following detailed description with reference to the attached drawing, which schematically presents the cross section of a folding box board according to the invention. The paperboard according to the invention comprises a fiber binder having, on the surface forming its reverse side, a surface sizing layer containing the marking agent. Such a cardboard can be used, for example, as a form of a package. In that case, it is essential that the marking agent be distributed uniformly over the entire width of the channel. Otherwise, there is a risk, depending on the size of the package, that the packaging made of the (printed) board does not contain particles of the marking agent at all. In accordance with the present invention, this problem can be solved by incorporation of the marking agent to surface sizing. As known per se, the purpose of surface sizing is to improve the moisture resistance of the paperboard (and thus the packaging). For this process step, it is therefore essential to provide the entire surface of the board with a size layer. According to the present invention, when the marking agent is applied to surface sizing, it is thus distributed in the production stage on a complete cardboard channel. This decreases the waste of material, which, in addition to the low consumption of the marking agent, lowers the production costs of printed materials, packaging and other authenticity products made from the channel.

It has been found that, in order to ensure uniform distribution, the particles of the marking agent must be less than 50 μm in size. In addition, it is advantageous if the particle size is greater than 0.05 μ. In general, the average particle size of the marking agent suitable for the invention is from 1 to 45 μm, preferably from 4 to 40 μm and more preferably from about 10 to 30 μm. If particles larger than 10 μ are used, an important advantage of the particles that are able to be visible to the eye as such is achieved. It is especially advantageous if the marking agent has an abrupt distribution that can be used to ensure the uniformity of the security marking consisting of the marking agent. Accordingly, from such material, one can make small and large boxes, which all have a desired marking agent, which contains a uniform surface. In a particularly advantageous manner, when the other surface of the paperboard is provided with a surface sizing layer, which typically does not contain marking agent, a printed or packaging is achieved, at each point of which there are both surfaces of authenticity and resistant to humidity. The labeling agent is preferably a substance that can be identified optically. Labeling agents suitable for the invention include, for example, those comprising particles that can be identified in UV light, those whose particles can be identified by means of IR radiation from X-ray radiation and those whose particles can be identified by laser, microscope, under the effect of heat, by means of a chemical reaction or biotechnological identification. Typical labeling agents include fluorescent inks, such as Rhodamine B (C. l. # 45175) and 2.2 '- (2,5-thiophendiyl) -bs (5-tert-bityl benzoxazole) and various stilbene derivatives, derivatives of cinnamenyl of benzene and biphenyl, pyrazolines and coumarin derivatives. Phosphorescent inorganic compounds, such as Eu doped yttrium oxysulfide and Eu doped yttrium phosphovanadate are also viable. Because the sizing mixtures are generally aqueous (see below), the marking agents are preferably formulated in dispersions or aqueous solutions. According to an advantageous embodiment of the invention, a pigment that changes its color or other properties when exposed to laser light is used as a marking agentSuch a pigment can, for example, be in the form of granules or wafers and the size of its particles is typically 0.05-20 μm, particularly advantageously 1-15 μm. By selecting the pigment, the wavelength range of light, for example, which leads to the desired result, can be affected. As an example, the pigment can be initially white and when it is sufficiently exposed to a laser light having a certain wavelength, it will be visibly darkened to the eye as it is. One of the advantages of a security configuration based on such a marking agent is that it can be maintained first without distinguishing but being revealed when necessary, for example, by the importer or end user of the product or state officials. Alternatively, the product manufacturer may apply a hard-to-counterfeit symbol on the product before releasing it to the market. The particles of the marking agent are at least mainly uniformly distributed in the surface sizing layer on the surface of the fiber binder. This means that their number per unit area in a selected part of the cardboard surface does not deviate by more than + 20%, particularly advantageously more than + 10%, from a corresponding number / unit of area, average, which is defined for the entire surface of the carton containing the marking agent. Typically, the surface sizing layer contains a water soluble, synthetic polymer, biopolymer or a derivative thereof. The superficial glueings can be divided into several groups, whereby there is the main division between cationic and anionic surface glueings. In addition to these, reactive sizes, such as alkylketene dimer (AKD), are used in surface sizing to a certain degree, pulp sizing being otherwise the main use thereof. Perfluorinated agents, such as perfluoroalkyl phosphate and perfluoroalkyl polymers can also be used. Cationic surface sizing includes cationic starches and starch derivatives and the corresponding carbohydrate-based biopolymers. Synthetic polymers can include, for example, styrene / acrylate (SA) copolymers, polyvinyl alcohols, polyurethanes and alkanized urethanes. Anionic surface sizes include anionic starches and corresponding starch derivatives and biopolymers based on carbohydrates, such as carboxymethylcellulose and its salts, alkylcelluloses, such as methyl and ethyl celluloses. Of synthetic polymers, the following could be cited: styrene / maleic acid (SMA) copolymer, di-isobutylene / maleic anhydride, styrene acrylate copolymers, acrylonitrile / acrylate copolymers and polyurethanes and corresponding latex products containing the same chemical functionalities . Many of the above substances are supplied as viscous solutions which are formed from the sodium or ammonia salts of the corresponding polycarboxylic acids. In general, the concentration of surface sizing in the solution is from about 0.01 to 25%, typically from about 1 to 15% by weight. The sizing is preferably mixed with water and any desired additive and auxiliary are added to the composition. These substances include, for example, anti-foaming agents, viscosity regulators, pH regulators and regulators. The labeling agent is added and mixed with the sizing to form an at least substantially homogeneous mixture, which is distributed on the reverse side. The surface sizing is carried out in a manner known per se by the use of conventional technology, for example, a film transfer magazine or press or by means of a rod coater. In this way, a layer containing the marking agent is formed on the surface of the fiber binder, its layer thickness being from approximately 0.1 to 1 00 μm, normally from approximately 0.5 to 50 μm. Such a layer contains approximately 50 to 25000, preferably approximately 1000 to 15000 particles of marking agent per dm2. Such a particle density is obtained by adding about 0.01 to 10% by weight of the marking agent to the sizing composition. The surface layer of the fiber binder can be left untreated, but is preferably glued on the surface and covered in a normal manner, for example, first with a precoated layer and then with at least one front cover layer. If the surface layer is glued on the surface, a free sizing of labeling agent is preferably used. In this case, both surfaces of the fiber binder can be glued by introducing the cardboard in double glueing, for example, in a deposit or transfer sizing press, whereby the sizing used in the surface sizing of the surface layer and, in a manner corresponding, the reverse side, remain separated from one another during gluing.

The invention can be used to provide conventional packaging board with a layer of marking agent, for example. The fiber binder of such cardboard consists, for example, of a single-layer product, a base board, which may comprise bleached or unbleached chemical hardwood pulp, bleached or unbleached bleached soft wood pulp, pulp bleached or unbleached mechanics, bleached or unbleached chemo-mechanical pulp and / or pulp of recycled waste from the manufacture of cardboard, or mixtures thereof. It may also comprise a product of multiple strata having at least two strata of successive fibers. An example of the multilayer board is a product comprising a combination of a first stratum of fiber having an outer surface and an inner surface, a second stratum of fiber, which is separated from the first stratum of fiber and which has an external surface and an internal surface, whereby the inner surface of the second stratum of fiber is installed on the inner side of the first stratum of fiber, and a third stratum of fiber, which fits between the first and second strata of fiber , whereby the fiber layers form the fiber binder of the paperboard and the fiber sizing layer containing the marking agent is installed on the outer surface of the first fiber layer, the outer layer constituting the reverse side of the paperboard. In such a product, which, in principle, corresponds to a so-called carton for conventional folding boxes, at least one of the fiber layers, first and second, comprises chemical cellulose pulp. The fiber strata, first and second, may comprise soft wood pulp and / or bleached or unbleached hardwood. The third stratum of fiber comprises mechanical or chemo-mechanical pulp, soft wood pulp or bleached or unbleached hardwood or recycled pulp waste from the manufacture of cardboard. The surface forming the outer surface of the fiber binder may have a surface sizing layer; however, it is preferably free of marking agent, as stated above. The partial strata of the product of multiple strata can also be attached to each other by means of gluing layers. The strata used can be the same substances that were used for the surface sizing layer of the reverse side mentioned above. Figure 1 appended presents a modified carton product for folding cartons corresponding to the above general description. In the figure, the reference number 1 means the fiber binder, which in the case of folded carton comprises three layers of fiber superimposed, of which the upper coating 2 and the reverse side 3 consist of chemical pulp mass bleached and center 4 consists of mechanical pulp, which possibly contains waste pulp obtained from processing. The folded carton is glued on the surface 5 on its surface and covered with two cover layers 6, 7, of which the first layer that comes on the upper coating 2 (the layer of the surface bonding 5) is a layer of pre-cover 6, which is generally thinner than the front cover layer 6. A typical layer thickness is approximately 1 to 100 μm, whereby the thickness of the pre-cover layer is approximately 20 to 60. % of the front cover layer. There may be several front cover layers 7, typically 1 to 3. In general, the amount of cover is approximately 5 to 50 g / m2. The surface of the reverse side 3 has a surface sizing layer 8 containing the marking agent. The average particle size of the sizing agent is essentially less than 50 μm; preferably not more than a small percentage (for example, from about 1 to 2%) of the particles are greater than 50 μm. Between the reverse side 3 and the center 4 and, correspondingly, the center 4 and the top coating 2, surface sizing layers 9, 10 are also provided. The reverse side may be provided with a cover layer 1 1. The folding carton according to the figure can be applied, for example, to packaging carton, whereby the authenticity of the packaging material can be confirmed inside the package, when it is illuminated with a UV light, for example. The following non-limiting examples illustrate the invention: Example 1 UV fluorescent particles with an average particle size of 40 μm were integrated into a paperboard product by two different methods by using the same amounts of material per surface area. In Method 1, the particles were mixed with the cellulose pulp of a reverse side corresponding to a typical production cardboard and laboratory sheets were prepared from the pulp, having a basis weight of 40 m2. The - of the sheets illustrate the reverse side of the folding carton. The amount of particles dosed was 0.12 mg / sheet on average. In Method 2, the particles were added to the surface of the sheet in a mixture with a starch-based sizing. The amount of sizing dosed on the sheet was about 5g / m2. In this way, the same amount of particles, 0.12 mg / sheet, was dosed in a mixture with the sizing. In both cases, a theoretical objective was to achieve a dose of 1000 particles per square decimeter. The definition by counting the actual number of particles per square decimeter for the sheets made by the two different methods resulted in approximately 600 particles / dm2 for the sheets made by Method 1 and over 900 particles / dm2 for the processed sheets It is obvious, therefore, that the addition of particles to the surface of the sheet together with gluing is considerably more profitable in terms of material economy. The reason for this is the low retention of particles relative to the sheet during the removal of water and the incrustation of the sheets within the fiber sheet. If the test had been carried out by a production-scale machine, where the drainage action would be more intense than under laboratory conditions, the difference between the methods would have been even greater.

Example 2 UV fluorescent particles of two different average particle sizes were added to the surface of a cardboard sheet together with starch-based sizing. The average particle size in Lot 1 was 70 μm with an amplitude distribution (50 to 200 μm) and in Lot 2, 40 μm with a narrow distribution. The size layer to be applied was 5 g / m2 and was made by means of a rod coater. The target dose in both cases was 1,000 particles / dm2 taking into account the different particle size distribution. The prepared sheets were determined under UV light, whereby it was discovered that the objective realized for sheets that were glued on the surface with Lot 1 was only about 600 particles / dm2 on average, while the objective realized for glued sheets On the surface with Lot 2 was over 900 particles / dm2 on average. When the glued sheets on the surface were further examined with Lot 1, it could be observed that the larger particles had left streaks and left the sheet together with the surface sizing rod.

Claims (34)

1. REIVI NDICATIONS 1. The cardboard used in products of authenticity, which comprises - a fiber binder having two surfaces, characterized in that the other surface of the fiber layer has a surface sizing layer containing a particle type marking agent with a particle size less than 50 μm. Cardboard according to claim 1, characterized in that the marking agent can be identified optically. Cardboard according to claim 1 or 2, characterized in that the marking agent comprises particles that can be identified in UV light, or particles that can be identified by IR radiation or X-ray radiation, or particles that can be identified by means of a laser, microscope, under the effect of heat or by means of a chemical reaction or biotechnological identification. Cardboard according to any one of the preceding claims, characterized in that the particles of the marking agent have been distributed at least mainly uniformly in the surface sizing layer on the surface of the fiber binder. Cardboard according to any of the preceding claims, characterized in that the surface sizing layer comprises a biopolymer or derivative thereof, such as starch, a starch derivative, a cellulose derivative or other additives in the surface sizing of paper and paperboard. Cardboard according to any of the preceding claims, characterized in that the average particle size of the marking agent is from 1 to 45 μm, preferably from 4 to 40 μm, and more preferably from approximately 1 to 30 μm. Cardboard according to any of the preceding claims, characterized in that the surface sizing layer contains approximately 50 to 25000, preferably approximately 1000 to 15000 particles of marking agent per dm2. Cardboard according to any one of the preceding claims, characterized in that the layer containing the surface sizing marking agent is distributed on the surface constituting the reverse side of the paperboard. Cardboard according to any one of the preceding claims, characterized in that the fiber binder consists of base board comprising bleached and / or unbleached hardwood pulp, bleached and / or unbleached softwood pulp, bleached mechanical pulp and / or non-bleached, chemo-mechanical pulp bleached and / or unbleached and / or recycled waste pulp used in the production of cardboard, or mixtures thereof. Cardboard according to any one of claims 1 to 8, characterized in that it comprises a multilayer product having at least two superposed fiber layers. eleven . Cardboard according to claim 10, characterized in that it comprises in combination: a first stratum of fiber having an external surface and an internal surface, a second stratum of fiber, which is installed at a distance from the first stratum of fiber and which has an external surface and an internal surface, whereby the internal surface of the second fiber layer is installed to face the internal surface of the first fiber layer, and a third layer of fiber, which is installed between the layers of fiber. fiber, first and second, whereby the fiber layers form the fiber binder of the paperboard and the layer containing surface sizing marking agent is installed on the outer surface of the first fiber layer constituting the reverse side of the paperboard. Paperboard according to claim 1, characterized in that at least one of the first and second fiber layers comprises chemical cellulose pulp. Cardboard according to claim 1 2, characterized in that the fiber layers, first and second, comprise soft wood pulp and / or bleached or unbleached hardwood. 14. Cardboard according to any of the preceding claims, characterized in that the third layer of fiber comprises mechanical or chemo-mechanical pulp, soft wood pulp or bleached or unbleached white wood or recycled waste pulp from the manufacture of cardboard, or mixtures thereof. Paperboard according to any one of the preceding claims, characterized in that there is a surface gluing layer on the surface constituting the external surface of the fiber binder. 16. Cardboard according to claim 15, characterized in that the surface sizing layer on the external surface of the fiber binder is free of marking agent. Cardboard according to any one of the preceding claims, characterized in that the partial strata of the product of multiple layers can be adhered to each other with gluing layers. Cardboard according to any one of the preceding claims, characterized in that the surface gluing surface, which forms the reverse side of the cardboard, is not covered. 19. Cardboard according to any of the preceding claims, characterized in that the external surface of the fiber binder is covered. 20. Cardboard according to claim 19, characterized in that the outer surface is covered with a pre-cover layer and at least one front cover layer. twenty-one . Cardboard according to any of the preceding claims, characterized in that it is in the form of a channel, sheet, graphic product, packaging or a form of a package. 22. A method for making paperboard for products of authenticity, according to which a fiber binder is provided, which is glued on the surface at least on the side forming the reverse side of the paperboard, characterized in that an agent of marking having a particle size of substantially less than 50 μm is incorporated in the surface sizing layer. 23. Cardboard according to claim 22, characterized in that a multilayer board is manufactured, which contains at least two layers of fiber superimposed, which forms the fiber binder. Cardboard according to claim 23, characterized in that a multilayer board is manufactured comprising a first layer of fiber having an internal surface and an external surface forming the reverse side of the board, a second layer of fiber, which is installed at a distance from the first stratum of fiber and which has an outer surface and an internal surface, whereby the inner surface of the second stratum of fiber is installed to meet the inner surface of the first stratum of fiber, and the surface external forms the upper part of the cardboard, and a third stratum of fiber, which is installed between the fiber layers, first and second, whereby the fiber layers together form the fiber binder of the cardboard, and the agent The marking is incorporated in the surface sizing layer installed on the external surface of the first fiber layer. 25. The method according to any of the claims 22 to 24, characterized in that the fiber binder is glued on the surface in a film transfer or gluing press or with a rod coater. 26. The method according to any of claims 22 to 25, characterized in that a surface sizing layer free of marking agents is embedded in the top coating of the fiber binder. 27. The method according to claim 26, characterized in that the board is introduced in double gluing, whereby the glueings used for the surface gluing of the upper coating and, correspondingly, the reverse side are kept separate from each other in connection with the gluing. The method according to any of claims 22 to 27, characterized in that the marking agent is mixed with a carbohydrate based sizing used for surface sizing in order to form a homogeneous mixture that is distributed on the reverse side. 29. The method according to any of claims 22 to 28, characterized in that approximately 50 to 25000, preferably approximately 100 to 1 5000, particles of marking agent per dm2 are incorporated in the reverse side surface sizing layer. 30. The method according to any of claims 22 to 29, characterized in that a marking agent is used, which can be identified optically. 31 The method according to any of claims 22 to 30, characterized in that a labeling agent is used which comprises fluorescent particles that can be identified in UV light, or particles that can be identified by IR radiation or X-ray radiation, or particles that can be identified by laser, microscope, under the effect of heat, by means of a chemical reaction or biotechnological identification. 32. The method according to any of claims 22 to 31, characterized in that a marking agent is used having an average particle size of 1 to 45 μm, preferably 4 to 40 μm; and more preferably about 10 to 30 μm. 33. The method according to any of claims 22 to 32, characterized in that the cardboard glued on the surface is covered. 34. The method according to claim 33, characterized in that the cover layer (s) are applied only to the surface of the upper layer.