Abstract
A method for embossing a barrier paper, wherein the barrier paper comprises paper and a protective layer on at least one of its sides. The method comprises providing a first embossing system with a first embossing tool and a second embossing tool cooperating with the first embossing tool to emboss the barrier paper: providing a patrix structure on the first embossing tool: providing a matrix structure on the second embossing tool: whereby the matrix structure corresponds to the patrix structure in such a manner that when embossing the barrier paper, a functionality of the protective layer is preserved. The method further comprises embossing the barrier paper by inserting the barrier paper between the first and the second embossing tools, applying pressure between the patrix and the matrix structures to press the patrix structure on a paper side which is a side of the barrier paper opposite to the side with the protective layer of the barrier paper, and push the barrier paper in the matrix structure, whereby the protective layer faces the matrix structure, thereby modifying a fiber structure of the paper in the barrier paper by at least one of the following effects: breaking of paper fibers, compressing of the paper fibers, densifying of the paper fibers; resulting in a modified folding behavior of the barrier paper and in maintaining a substantially unchanged shape of the barrier paper over its lifetime.
Claims
1-62. (canceled)
63. A method for embossing a barrier paper, wherein the barrier paper comprises paper and a protective layer on at least one of its sides, the method comprising providing a first embossing system with a first embossing tool and a second embossing tool cooperating with the first embossing tool to emboss the barrier paper; providing a patrix structure on the first embossing tool; providing a matrix structure on the second embossing tool; whereby the matrix structure corresponds to the patrix structure in such a manner that when embossing the barrier paper, a functionality of the protective layer is preserved; and embossing the barrier paper by inserting the barrier paper between the first and the second embossing tools, applying pressure between the patrix and the matrix structures to press the patrix structure on a paper side which is a side of the barrier paper opposite to the side with the protective layer of the barrier paper, and push the barrier paper in the matrix structure, whereby the protective layer faces the matrix structure, thereby modifying a fiber structure of the paper in the barrier paper by at least one of the following effects: breaking of paper fibers, compressing of the paper fibers, densifying of the paper fibers; resulting in a modified folding behavior of the barrier paper and in maintaining a substantially unchanged shape of the barrier paper over its lifetime.
64. The method for embossing of claim 63, further comprising heating at least one of the first and second embossing tools, and/or the barrier paper at the step of embossing the barrier paper.
65. The method of claim 63, wherein the protective layer comprises an added layer of material different than that of the paper, configured to provide determined barrier properties, or a layer-zone of paper modified to provide the determined barrier properties.
66. The method of claim 63, wherein in order to preserve the functionality of the protective layer, the patrix structure and the matrix structure are configured such that a first junction between a lateral side of the patrix structure and a first base surface of the first embossing tool from which the patrix structure protrudes is substantially a first circular arc having a first radius R1, and a second junction between a lateral side of the matrix structure and a second base surface of the second embossing tool in which the matrix structure is made, is substantially a second circular arc having a second radius R2, whereby R2>R1.
67. The method of claim 66, wherein the first radius R1 is larger than 15 ?m.
68. The method of claim 63, wherein in order to preserve the functionality of the protective layer, the patrix structure is configured to comprise at a summit of the patrix structure a first surface S1 and the matrix structure is configured to comprise at a bottom of the matrix surface a second surface S2, such that when a first embossing force (F) is applied to the patrix structure a first local contact pressure F/S1 with the paper side on the side of the patrix structure has a value greater than a second local contact pressure F/S2 with the protective layer on the side of the matrix structure.
69. The method of claim 63, wherein the barrier paper comprises an additional protective layer on a side of the barrier paper opposite to the side of the protective layer, and in order to preserve the integrity of the protective layer, the patrix structure and the matrix structure are configured such that a first junction between a lateral side of the patrix structure and a first base surface of the first embossing tool from which the patrix structure protrudes is substantially a first circular arc having a first radius R1, and a second junction between a lateral side of the matrix structure and a second base surface of the second embossing tool in which the matrix structure is made, is substantially a second circular arc having a second radius R2, whereby the first radius R1 and the second radius R2 differ by less than 25%.
70. The method of claim 69, wherein the first radius R1 and the second radius R2 are each larger than 25 ?m.
71. An apparatus for embossing a barrier paper, wherein the barrier paper comprises paper and a protective layer on at least one of its sides, the apparatus comprising a first embossing system with a first embossing tool and a second embossing tool which is configured to cooperate with the first embossing tool to emboss the barrier paper; a patrix structure on the first embossing tool; a matrix structure on the second embossing tool; whereby the matrix structure corresponds to the patrix structure in such a manner that at a time of embossing the barrier paper, a functionality of the protective layer is preserved; and whereby further the first embossing system is configured to receive the barrier paper when it is inserted between the first and the second embossing tools, and to apply a pressure between the patrix and the matrix structure to press the patrix structure on the paper side of the barrier paper, and push the barrier paper in the matrix structure, whereby the protective layer faces the matrix structure, thereby modifying a fiber structure of the paper in the barrier paper by at least one of the following effects: breaking paper fibers, compressing of the paper fibers, densifying of the paper fibers; resulting in a modified folding behavior of the barrier paper and in maintaining a substantially unchanged shape of the barrier paper over its lifetime.
72. The apparatus of claim 71, further comprising a heating means configured to heat at least one of the first and second embossing tools, and/or the barrier paper at the time of embossing the barrier paper.
73. The apparatus of claim 71, wherein the protective layer comprises an added layer of material different than that of the paper, configured to provide determined barrier properties, or a layer-zone of paper modified to provide the determined barrier properties.
74. The apparatus of claim 71, wherein in order to preserve the integrity of the protective layer, the patrix structure and the matrix structure are configured such that a first junction between a lateral side of the patrix structure and a first base surface of the first embossing tool from which the patrix structure protrudes is substantially a first circular arc having a first radius R1, and a second junction between a lateral side of the matrix structure and a second base surface of the second embossing tool in which the matrix structure is made, is substantially a second circular arc having a second radius R2, whereby R2>R1.
75. The apparatus of claim 74, wherein the first radius is larger than 15 ?m.
76. The apparatus of claim 71, wherein in order to preserve the integrity of the protective layer, the patrix structure is configured to comprise at a summit of the patrix structure a first surface S1 and the matrix structure is configured to comprise at a bottom of the matrix surface a second surface S2, such that when a first embossing force (F) is applied to the patrix structure a first local contact pressure F/S1 with the paper side on the side of the patrix structure has a value greater than a second local contact pressure F/S2 with the protective layer on the side of the matrix structure.
77. The apparatus of claim 71, wherein the barrier comprises an additional protective layer on a side of the barrier paper opposite to the side of the protective layer, and in order to preserve the integrity of the protective layer, the patrix structure and the matrix structure are configured such that a first junction between a lateral side of the patrix structure and a first base surface of the first embossing tool from which the patrix structure protrudes is substantially a first circular arc having a first radius R1, and a second junction between a lateral side of the matrix structure and a second base surface of the second embossing tool in which the matrix structure is made, is substantially a second circular arc having a second radius R2, whereby the first radius R1 and the second radius R2 differ by less than 25%.
78. The apparatus of claim 77, wherein the first radius R1 and the second radius R2 are each larger than 25 ?m.
79. A method for embossing a barrier paper, wherein the barrier paper comprises a protective layer on at least one of its sides, the method comprising providing a first embossing system with a first embossing tool and a second embossing tool cooperating with the first embossing tool to emboss the barrier paper; providing a patrix structure on the first embossing tool; providing a matrix structure on the second embossing tool; whereby the matrix structure corresponds to the patrix structure in such a manner that when embossing the barrier paper, a functionality of the barrier paper is preserved; embossing the barrier paper by inserting the barrier paper between the first and the second embossing tools, applying pressure between the patrix and the matrix structures to press the patrix structure on a side of the barrier paper with the protective layer, and push the barrier paper in the matrix structure, whereby a paper side of the barrier paper faces the matrix structure, thereby modifying a fiber structure of the paper in the barrier paper by at least one of the following effects: breaking of the paper fiber, compressing of the paper fibers, densifying of the paper fiber; resulting in a modified folding behavior of the barrier paper and in maintaining a substantially unchanged shape of the barrier paper over its lifetime.
80. An apparatus for embossing of a barrier paper, wherein the barrier paper comprises paper and a protective layer on one of its sides, the apparatus comprising a first embossing system with a first embossing tool and a second embossing tool which is configured to cooperate with the first embossing tool to emboss the barrier paper; a patrix structure on the first embossing tool; a matrix structure on the second embossing tool; whereby the matrix structure corresponds to the patrix structure in such a manner that at a time of embossing the barrier paper, a functionality of the protective layer is preserved; whereby further the first embossing system is configured to receive the barrier paper when it is inserted between the first and the second embossing tools, and to apply a pressure between the patrix and the matrix structure to press the patrix structure on a side of the barrier paper with the protective layer, and push the barrier paper in the matrix structure, whereby a paper side of the barrier paper faces the matrix structure, thereby modifying a fiber structure of the paper in the barrier paper by at least one of the following effects: breaking paper fibers, compressing of the paper fibers, densifying of the paper fibers; resulting in a modified folding behavior of the barrier paper and in maintaining a substantially unchanged shape of the barrier paper over its lifetime.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0092] The invention will be better understood through the description of preferred examples of embodiments and in reference to the drawings, wherein FIG. 1 illustrates examples of barrier paper;
[0093] FIG. 2 schematically illustrates an embossing apparatus and a barrier paper embossed therewith according to an example embodiment of the invention;
[0094] FIG. 3 schematically illustrates an embossing system used in the embossing apparatus in an assembled and in an exploded view;
[0095] FIG. 4 schematically illustrates configurations of barrier paper embossed with a macroscopic structure according to example uses of the invention;
[0096] FIG. 5 schematically illustrates cooperating embossing tools with a view of radii used to preserve a functionality of a protective layer after embossing (barrier paper and protective layer not illustrated) according to a preferred example embodiment of the invention;
[0097] FIG. 6 illustrates how local contact pressure between barrier paper and embossing tools may be adjusted in order to preserve a functionality of a protective layer after embossing according to a preferred example embodiment of the invention;
[0098] FIG. 7 schematically illustrates an embossing apparatus and barrier paper embossed therewith according to example embodiments of the invention;
[0099] FIG. 8 illustrates embossing systems configured to emboss microscopic structures in a protective layer according to example embodiments of the invention;
[0100] FIG. 9 illustrates an embossing apparatus comprising two embossing systems, and the embossing effect produced on a barrier paper according to an example embodiment of the invention;
[0101] FIG. 10 illustrates separate stages of an embossing method, also involving providing gap between a patrix structure and a matrix structure according to an example embodiment of the invention;
[0102] FIG. 11 illustrates a number of products of embossed barrier paper that may be produced by means of the example embodiments of the invention;
[0103] FIG. 12 illustrates an example of an embossed macrostructure in a barrier paper, that may be produced by means of a preferred embodiment of the invention;
[0104] FIG. 13 illustrates examples of creasings embossed in a barrier paper by means of a preferred embodiment of the invention;
[0105] FIG. 14 illustrates examples of packaging materials in form of barrier paper embossed by means of a preferred embodiment of the invention; and
[0106] FIG. 15 illustrates a further example of packaging material in form of a barrier paper embossed by means of a further preferred embodiment of the invention.
[0107] Same references will be used to designate same or similar features throughout all the figures.
DETAILED DESCRIPTION OF PREFERRED EXAMPLES OF EMBODIMENT OF THE INVENTION
[0108] It has been found through experimentation that combined embossing of the above-described technologies of prior art in barrier paper with a single pair of embossing rollers, or a successive embossing of barrier paper in separate embossing systems of the above-described technologies of prior art (microscopic structures and macroscopic structures) surprisingly provides an embossed product that demonstrates a new synergy of effects, i.e., in which improved possibilities of folding of the packaging material, and improved properties of the embossed protective layers are achieved.
[0109] The invention provides a method for embossing a barrier paper comprising a protective barrier zone on anyone of its sides or on both of its sides in which a functionality of the embossed protective layer(s) may be enhanced, but also an improved possibility of folding the barrier paper is obtained. The invention further provides a corresponding apparatus.
[0110] FIGS. 1a and 1b illustrate examples of barrier paper that may be embossed by means of the method and apparatus of the invention. Barrier paper as such is a product well known in the art, which also continuously continues to be developed and improved. More information about barrier paper and its protective layers is given in the above section definitions and vocabulary. FIG. 1a shows an example of a barrier paper 104 which comprises a sheet of paper 100 and a protective layer 101 on one of the sides of the paper 100. FIG. 1b shows an example of a barrier paper 105 which comprises the sheet of paper 100 and protective layers 102 and 103 on respective sides of the paper 100. The protective layers 102 and 103 may or may not be of same nature, and may be adapted in their constituency depending on the intended use of the barrier paper 105.
[0111] FIGS. 2a, 2b and 2c schematically illustrate an embossing apparatus 200 and a barrier paper 104 being embossed therewith according to an example embodiment of the invention. FIG. 2a represents the embossing apparatus 200 which comprises a first embossing tool 201 embodied as an embossing roller and a second embossing tool 202 also embodied as an embossing roller, and configured to cooperate with the first embossing tool 201. Of course, the first embossing tool 201 and the second embossing tool 202 are part of an embossing system which may comprise a frame, a cassette, and pressure-applying means not illustrated here for an easier readability. The barrier paper 104, a section of which is shown in magnified view of FIG. 2b, may be fed to the embossing system to be embossed between the first embossing tool 201 and the second embossing tool 202. FIG. 2c is a magnified view of the barrier paper 104 being embossed by the first embossing tool 201 and the second embossing tool 202. More precisely, the first embossing tool 201 is provided with a patrix structure 203. The patrix structure 203 is explained in the section definitions and vocabulary herein above together with a matrix structure. As such, the patrix structure 203 is a positive projection of a structure to emboss, departing from a mean surface 204 of the patrix-embossing tool 201the first embossing tool 201 is a patrix-embossing tool. The second embossing tool 202, which is a matrix-embossing tool, is provided with a matrix structure 205, which enter a mean surface 206 of the second embossing tool 202, and is complementary to the patrix structure 203. In a preferred embodiment, the matrix structure 205 and the patrix structure 203 are non-congruent, as described in prior art herein above. The matrix structure 205 corresponds to the patrix structure 203 in such a manner that when embossing the barrier paper 104, a functionality of the protective layer 101 is preserved, i.e., no functional deterioration of the protective layer 101 is caused by the effect of embossing. The barrier paper 104 is being embossed by a pressing of the patrix structure 203 on the paper side 100, which is the side of the barrier paper 104 opposite to the side with the protective layer 101. This pushes the barrier paper 104 in the matrix structure 205, whereby the protective layer 101 faces the matrix structure 205. This may modify a fiber structure of the paper 100 in the barrier paper 104 by at least one of the following effects: breaking of paper fibers, compressing of the paper fibers, densifying of the paper fibers; resulting in a modified folding behavior of the barrier paper and in maintaining a substantially unchanged shape of the barrier paper over its lifetime.
[0112] FIGS. 3a and 3b schematically illustrate an embossing system 300 used in the embossing apparatus and method to emboss the barrier paper 104. FIG. 3a illustrates the embossing system 300 in an assembled state, where a path of the barrier paper 104 being embossed is also visible, while FIG. 3b gives a simplified exploded view comprising various component of the embossing system 300, including a mount 301, a generally cylindrical sleeve supporting the roller 302 for mounting the first embossing tool 201 and a fork 303 for mounting the second embossing tool 202 in the mount 301.
[0113] The embossing system 300 may preferably be configured as a quick exchange device, as is defined in the dedicate definition and vocabulary section above.
[0114] FIGS. 4a and 4b schematically illustrate configurations of the barrier paper 104 being embossed with a macroscopic structure between a patrix embossing tool P and a matrix embossing tool M. The tools are only suggested but not textured in the figure on each side of the barrier paper 104. In the example use of the invention in FIG. 4a the barrier paper 104 has the protective layer 101 towards the patrix tool P, i.e., a patrix structure 400 pushes against the protective layer 101. In the example use of the invention in FIG. 4b the barrier paper 104 has the protective layer 101 towards the matrix tool M, i.e., the patrix structure 400 pushes against the paper side 100 while the protective layer 101 is towards a matrix structure 401.
[0115] FIG. 5 schematically illustrates cooperating embossing tools, i.e., the patrix embossing tool P and the matrix embossing tool M, with a view of radii R1 and R2 in these tool as used to preserve a functionality of the protective layer (barrier paper and protective layer not illustrated in FIG. 5) of a barrier paper 104 after embossing according to a preferred example embodiment of the invention. In a preferred embodiment, the barrier paper has a single side with a protective layer. The barrier paper 104 to be embossed may for example have a thickness that is larger than 30 ?m but generally below 300 ?m, whereby thickness of the protective layer is typically in a range between 5 and 50 ?m. It seems that a junction between a lateral side 502 of a patrix structure 501 and the base (mean) surface 503 of an embossing tool 504 from which the patrix structure 501 protrudes, and a junction between a lateral side 505 of a matrix structure 500 and the base (mean) surface 506 of an embossing tool 507 in which the matrix structure 500 recesses are potential zones of fracture during embossing and require for particular considerations.
[0116] In a preferred embodiment of the invention, with the protective layer facing the matrix structure 500 (barrier paper and protective layer not illustrated in FIG. 5), the junction between the lateral side 502 of the patrix structure 501 and the base surface 503 of the embossing tool 504 from which the patrix structure 501 protrudes is substantially a first circular arc having a first radius R1, and the junction between the lateral side 505 of the matrix structure 500 and the base surface 506 of the embossing tool 507 in which the matrix structure 500 is made, is substantially a second circular arc having a second radius R2, whereby R2>R1. In a further preferred embodiment, R1 is larger than 15 ?m, preferably larger than 25 ?m.
[0117] In a further preferred embodiment of the invention, with the protective layer facing the patrix structure 501 (barrier paper and protective layer not illustrated in FIG. 5), the junction between the lateral side 502 of the positive projection of the patrix structure 501 and the base surface 503 of the embossing tool 504 from which the patrix structure 501 protrudes is substantially a first circular arc having a first radius R1, and the junction between a lateral side 505 of the negative projection of the matrix structure 500 and the base surface 506 of the embossing tool 507 in which the matrix structure 500 is made, is substantially a second circular arc having a second radius R2, whereby R1>R2. In a further preferred embodiment, R2 is larger than 15 ?m, preferably larger than 25 ?m.
[0118] In a further preferred embodiment of the invention, when embossing the barrier paper 100 having protective layers 102 and 103 on its two sides to be embossed, for example as depicted in the barrier paper 100 of FIG. 1b but not in FIG. 5, the radius R2 and the radius R1 differ by less than 25%. In a further preferred embodiment when embossing the barrier paper 100 having protective layers 102 and 103 on its two sides, R1 and R2 are larger than 25 ?m, preferably larger than 40 ?m.
[0119] It is understood that the proportions and dimension illustrated in FIG. 5 are schematic only and do not represent a real case with actual measures and proportions. Only the relation between R1 and R2 and the example values indicated in the preceding paragraphs are to be taken into consideration.
[0120] It has been empirically verified that the use of junctions with radii that exceed the minimal value as explained herein, has the advantage of reducing the shear stress as the barrier paper 104 is quenched between the patrix structure 501 and the matrix structure 500.
[0121] FIGS. 6a and 6b illustrate how local contact pressure between barrier paper 104 and embossing tools, i.e., patrix embossing tool P and matrix embossing tool M, may be adjusted in order to preserve a functionality of the protective layer 101 after embossing according to preferred example embodiments of the invention. A reducing of the local contact pressure has a beneficial effect throughout embossing the protective layer 101 of the barrier paper 104 and it may be understood in view of the illustration in FIGS. 6a and 6b, which each depict a single patrix structure 600, 602 and a single matrix structure 601, 603, and in view of the explanations given hereinafter.
[0122] As illustrated in the FIG. 6a, in which the barrier paper 104 has the protective layer 101 facing the matrix structure 601 and the paper side 100 facing the patrix structure 600, an embossing force F is applied to the patrix structure 600. It has been empirically found that a surface S1 at a summit of the patrix structure 600 corresponding to a feature intended to be embossed needs to be smaller than a surface S2 at a bottom of the matrix structure 601 corresponding to the feature intended to be embossed in the barrier paper 104.
[0123] Therefore, a first local contact pressure F/S1 on the patrix side, i.e., on the paper side 100 is larger than a second local contact pressure F/S2 on the matrix side, i.e., on the protective layer side 101. As a larger local contact pressure directly implies a larger probability to disrupt the protective layer 101, the advantage of embossing the barrier paper 104 with the protective layer 101 facing the matrix structure 601, i.e., facing the smaller contact pressure, is that of preserving an integrity of the protective layer 101.
[0124] In a further preferred embodiment, the embossing of the barrier paper 104 occurs with the protective layer 101 facing the patrix structure 602, as illustrated in FIG. 6b. In this case a surface S3 at the summit of the patrix structure 602 needs to be chosen to be greater than or at most equal to a surface S4 at a bottom of the matrix structure 603 corresponding to the feature intended to be embossed in the barrier paper 104.
[0125] Upon this choice of S3 and S4, a third local contact pressure F/S3 on the patrix side is smaller than a fourth local contact pressure F/S4 on the matrix side. As a larger local contact pressure directly implies a larger probability to disrupt the protective layer 101, the benefit of embossing the barrier paper 104 with the protective layer 101 facing the adapted patrix structure 602, i.e., facing the smaller local contact pressure, is that of preserving an integrity of the protective layer 101.
[0126] FIGS. 7a, 7b, 7c and 7d schematically illustrate an embossing apparatus 708 and barrier paper 104, 105 embossed therewith according to example embodiments of the invention. In a preferred embodiment of the invention as illustrated in FIGS. 7a and 7b, in order to produce a superposition of microscopic embossed features 700, 701 and macroscopic embossed features 702, 703, 704, 705 on the barrier paper 104, the microscopic 700, 701 and the macroscopic 702, 703, 704, 705 structures are combined on at least one of a patrix roller P and the matrix roller M, facing the protective layer 101. Further, in FIG. 7b, a space 720 between a matrix structure 705 of a matrix roller M and a sheet of paper 100 of an embossed barrier paper 104 occurs during embossing, because the patrix structure 704 is chosen non-congruent to the matrix structure 705 and it has a shortened height as compared to the patrix structure 702 in FIG. 7a. In a particular embodiment as illustrated in FIG. 7c, the barrier paper 105 with protective layers 102, 103 on both faces is embossed on both of its sides with microscopic structures 706, 707, i.e., both the patrix roller P and the matrix roller M may carry microscopic structures 706, 707.
[0127] As shown in FIG. 7d, an embossing apparatus 708 configured to perform the embossing comprises a patrix roller 709/P and a matrix roller 710/M, both mounted in a cassette (not shown in FIG. 7d) of the embossing apparatus 708, designed in such a manner that a force (not illustrated in FIG. 7d) can be applied between the patrix roller 709/P and the matrix roller 710/M. The cassette and a force-generating device (not illustrated in FIG. 7d), e.g., a pneumatic cylinder, are embodied in a frame 711, building the embossing apparatus 708 according to an example of the present invention.
[0128] Preferably, the embossing apparatus 708 comprises a heating means (not illustrated in FIG. 7d) configured to heat at least one of the patrix roller 709/P, matrix roller 710/M, and/or the protective layer(s) 101, 102, 103 of the barrier paper 104, 105, in order to facilitate a plastic deformation of the protective layer(s) 101, 102, 103 and hence the embossing of microscopic structures 700, 701, 706, 707 into the protective layer(s) 101, 102, 103 of the barrier paper 104, 105. Temperatures above 40? C., preferably above 70? C. are suitable, whereby temperatures exceeding a certain limit, e.g., 150? C. will damage the barrier paper.
[0129] In the case of the patrix roller 709/P for use cases illustrated in FIGS. 7b and 7c with patrix structures 704 and 712 respectively, the microscopic structures 701, 707 are preferably carried by a top surface 713, 714 at a summit of the patrix structure 704, 712 corresponding to an embossed macroscopic feature (the feature has different shapes between FIGS. 7b and 7c), whereby in the case of the matrix roller 710/M, i.e., for the use case illustrated in FIG. 7a with matrix structure 703, the microscopic structures are preferably carried by the base mean surface 715 of the matrix roller 710/M, surrounding the matrix structure 703, while a corresponding surface on the patrix roller P, i.e., a surface opposite to the microscopic structures 700 on the other side of the barrier paper 104 at the time of embossing, is a smooth surface.
[0130] The barrier paper 104, 105 is fed into the embossing apparatus 708 such that the protective layer 101, 102, 103 of the barrier paper 104, 105 faces the patrix roller 709 and/or the matrix roller 710, depending on the case, that carries the microstructures 700, 701, 706, 707 and the output is a macro-embossed barrier paper 104, 105 with a micro-structured protective layer 101, 102, 103.
[0131] FIGS. 8a, 8b, 8c and 8d illustrate embossing systems 800, 801 configured to emboss microscopic structures 802 into the protective layer 101 according to example embodiments of the invention. Each embossing system 800, 801 comprises a third embossing tool 804 and a fourth embossing tool 803, which are configured to cooperate with each other to emboss the barrier paper 104. The third embossing tool 804 is provided with at least a smooth surface structure 805, which in all the figures discussed here covers the whole cylindrical surface of the embossing tool 804. The fourth embossing tool 803 is provided with a plurality of microscopic structures 802 protruding from a surface 806 of the embossing tool 803. In FIG. 8a the microscopic structures 802 occupy a ring-shaped surface 807 on the cylindrical surface of the fourth embossing tool 803, while in FIG. 8b the microscopic structures 802 cover the whole cylindrical surface of the embossing tool 803. FIGS. 8a and 8b are examples only and other distributions of the microscopic structures 802 are possible. In FIG. 8c the microscopic structures 802 are represented by crosses. In the magnified view of FIG. 8d, the microscopic structures 802 are shown in proximity to the protective layer 101, suggesting that the microscopic structures 802 are just about to be embossed in the protective layer 101.
[0132] In a preferred embodiment of the invention, microscopic structures are engraved (as in FIGS. 8a, 8b, 8c, and 8d) in a surface of a roller (such as embossing roller tool 803 for example), such as a plurality of half-spheres, of cones, of regularly- or randomly-shaped surface topography features. In further embodiments, microscopic structures may be engraved in a surface of a patrix structure of a patrix roller corresponding to a macroscopic feature to be embossed or in a surface of a base surface of a matrix roller.
[0133] The plurality of surface microscopic structure(s) may imply an array of regularly distributed features, with periodic arrangements, may imply collection(s) of different types of structures, or may imply randomly distributed structures.
[0134] A lateral dimension of such individual microscopic surface structures may vary between 1 and 100 ?m, whereas a distance between two adjacent microscopic surface structures may vary between 2 and 200 ?m.
[0135] A maximal height of the microscopic surface structures is restricted by the thickness of the protective layer of the barrier paper to be embossed, as the integrity of the latter has to be preserved upon embossing the microscopic surface features. In a preferred embodiment, this height should not exceed 80% from the thickness of the protective layer of the barrier zone.
[0136] There is no particular technical minimal limit of the height of the microscopic surface features; this should be larger than the inherent surface roughness of the barrier zone and could be, typically, higher than 1 ?m.
[0137] FIGS. 9a, 9b, 9c and 9d illustrate embossing apparatuses 902 and 903 comprising two embossing systems, and the embossing effect produced on a barrier paper 104 according to an example embodiment of the invention. In the preferred embodiment illustrated in FIGS. 9a, 9b, 9c, 9d, in order to produce a superposition of embossed microscopic structure(s) 900 and embossed macroscopic structure(s) 901 embossing on the barrier paper 104, whereby microscopic structures 900 are embossed into the protective layer 101 of the barrier paper 104, two embossing apparatuses 902 and 903 are combined, such that barrier paper 104 embossed primarily by the second embossing apparatus 902, already carries the embossed microscopic structures on the protective layer 101 when it is fed into the first embossing apparatus 903 that is configured to perform the macroscopic embossing 901, and is further designed in such a manner that the macroscopic embossing is performed without pressing (flattening) the previously embossed microstructures 900.
[0138] The second embossing apparatus 902 performing the embossing of microscopic structures 900 comprises a surface structured roller 904, preferably with microscopic structures as previously described, and a smooth surface counter-roller 905, both mounted in a cassette (not illustrated in FIG. 9a), designed in such a manner that a force can be applied between the surface structured roller 904 and the smooth surface counter-roller 905. The cassette and a force generating device (not illustrated in FIG. 9a), e.g., a pneumatic cylinder, are embodied in a frame 908, building the first embossing apparatus 902 for microstructures embossing according to the present invention.
[0139] Preferably, the second embossing apparatus 902 performing the embossing of microscopic structure 900 comprises a means for heating (not illustrated in FIG. 9a) that is configured to heat the surface structured roller 904 and/or the protective layer 101, in order to facilitate the plastic deformation of the protective layer 101 and thus also the microscopic embossing into the protective layer 101 of the barrier paper 104. Temperatures above 40? C., preferably above 70? C. are suitable, whereby temperatures exceeding a certain limit, e.g., 150? C. will damage the barrier paper.
[0140] Alternatively, the microscopic structure(s) 900 are transferred from the surface structured roller 904 into a UV-sensible protective layer (not illustrated in the figures), which is UV-cured after the transfer, constituting a microstructured protective layer 101 of the barrier paper 104.
[0141] The first embossing apparatus 903 performing the embossing of macrostructures 901 comprises a patrix roller 907 and a matrix roller 906, both mounted in a cassette (not illustrated in FIG. 9a), designed in such a manner that a force can be applied between the patrix roller 907 and the matrix roller 906. The cassette and a force-generating device (not illustrated in FIG. 9a), e.g., a pneumatic cylinder, are embodied in a frame 909, building the second embossing apparatus 903 for macrostructures embossing according to the present invention.
[0142] In a particular embodiment of the invention illustrated in FIGS. 10a, 10b and 10c, a gap 1000 between a patrix structure 1001 of a patrix roller 1002 in the first embossing apparatus 903 and a corresponding matrix structure 1003 of a matrix roller 1004 is chosen to be configured as to be larger at the time of embossing barrier paper 104 than the thickness of the barrier paper 104, i.e., the thickness of paper 100 added to the thickness of the protective layer 101, this at least on one section, preferably between 5 ?m and 50 ?m. This locally enlarged distance created by the gap 1000 between the patrix structure 1001 and the matrix structure 1003 allows performing the macroscopic embossing of the barrier paper 104 without pressing (flattening) the microstructures 900 previously embossed by the second embossing apparatus 902 and thus existing on the protective layer 101 of the barrier paper 104.
[0143] The barrier paper 104 is fed into the microstructure embossing apparatus 902 such that the protective layer 101 of the barrier paper 104 faces the surface microstructured roller 904 and the paper side 100 faces the smooth surface counter-roller 905.
[0144] The embossed barrier paper 104 as output of the microstructure embossing apparatus 902, i.e., the barrier paper 104 with the microstructured protective layer 101, is subsequently fed into the macrostructure embossing apparatus 903.
[0145] The embossed barrier paper 104 as output of the macrostructure embossing apparatus 903 is a macro-embossed barrier paper 104 with the protective layer 101 that carries embossed microscopic structure(s) 900 on its surface. The microscopic structure(s) 900 may enhance the barrier properties of the barrier paper 104 and may compensate possible functionality losses that may occur due the macroscopic embossing.
[0146] FIGS. 11a to 11e illustrate a number of products of embossed barrier paper that may be produced by means of example embodiments of the invention. The barrier paper in FIGS. 11a to 11c is overall embossed with regularly spaced and distributed patterns, honeycombs in FIG. 11a, triangles in FIG. 11b and circles in FIG. 11c, which have the advantage of maintaining a substantially unchanged shape of the barrier paper over its lifetime. The patterns are obtained by macroscopic structure embossing as described in the present document. Each product may be further embossed using microscopic structures as explained in the present document. The product in FIG. 11d is a sheet of barrier paper in which macroscopic embossing is applied to obtain a few creasing lines, which have the advantage of privileging determined lines for an easy folding. Of course, the product may be further embossed using microscopic structures as explained in the present document. The product in FIG. 11e is based on the product of FIG. 11d to which embossing of logo patterns (displaying the term LOGO is the present example) is made using either macroscopic embossing, microscopic embossing or even the two types in combination according to explanations given in the present document.
[0147] FIGS. 12a to 12c illustrate an example of an embossed macrostructure pattern in a barrier paper 104, that may be produced by means of a preferred embodiment of the invention involving an embossing system 1200. The latter comprises a patrix tool 1201 and a corresponding matrix tool 1202 which is configured to cooperate as shown in the magnified illustration of FIG. 12c. The protective layer 101 (not illustrated in FIG. 12) faces the matrix toll 1202. The patrix tool 1201 and matrix tool 1202 comprise patrix structures 1203 and corresponding, non-congruent matrix structures 1204 as shown in FIG. 12c. These are distributed over respective surfaces of the patrix tool 1201 and the matrix tool 1202 to produce the embossed pattern illustrated in FIG. 12b.
[0148] FIGS. 13a and 13b illustrate examples of creasing lines 1300 embossed in a barrier paper 104 by means of a preferred embodiment of the invention, i.e., by means at least of macroscopic structures (not illustrated in the FIGS. 13a and 13b), wherein a patrix structure was used on a side labelled P to press on the paper side 100 of the barrier paper 104, and the protective layer 101 was facing the corresponding matrix structure labelled M. The product in FIG. 13a comprises a single creasing line, while that in FIG. 13b comprises a sequence of 3 consecutive creasing lines.
[0149] FIGS. 14a to 14c illustrate examples of packaging materials in form of barrier paper embossed by means of a preferred embodiment of the invention. More specifically the barrier paper in FIG. 14b was macroscopically embossed to obtain 4 creasing lines designed to privilege a folding of the barrier paper along these lines such that it may be used as inner-liner inside the cigarette box of FIG. 14a. FIG. 14c is a magnified cross-sectional view through one of the creasing lines of FIG. 14b which indicates that the line was obtained by embossing of macrostructures, the paper side being on the side of the patrix structure, and the protective layer on the side of the matrix tool that were used to emboss the barrier paper (note that the patrix and matrix structure are not illustrated).
[0150] FIGS. 15a and 15b illustrates a further example of packaging materials in form of barrier paper embossed by means of a preferred embodiment of the invention. More specifically the barrier paper in FIG. 15a was macroscopically embossed to obtain at least one creasing line designed to privilege a folding of the barrier paper along this lines such that it may be used as a flap for sealing a chocolate bar packaging. FIG. 15b is a magnified cross-sectional view through the creasing line of FIG. 15a which indicates that the line was obtained by embossing of macrostructures and microstructures (as shown by crosses on the illustrated paper), the paper side being on the side of the patrix structure, and the protective layer on the side of the matrix tool that were used to emboss the barrier paper (note that the patrix and matrix structure are not illustrated). The microscopic structures are embossed on the protective layer towards the matrix side.
