U.S. patent application number 10/585191 was filed with the patent office on 2008-12-04 for method for producing identification marks on paper or board and a marked material made with the method.
This patent application is currently assigned to Stora Enso Oyj. Invention is credited to Nina Miikki, Jari Rasanen, Erkki Teva.
Application Number | 20080295984 10/585191 |
Document ID | / |
Family ID | 30129316 |
Filed Date | 2008-12-04 |
United States Patent
Application |
20080295984 |
Kind Code |
A1 |
Miikki; Nina ; et
al. |
December 4, 2008 |
Method for Producing Identification Marks on Paper or Board and a
Marked Material Made with the Method
Abstract
The invention comprises a method for producing identification
marks (5) on layer-structured paper or board (7) to be manufactured
in a continuous web and the marked papers and boards obtained with
this method. With this method, the marks (5) are made with a laser
beam on a moving web form fiber layer (1), on which a second layer
of material (6) is subsequently overlaid in such a way that the
marks remain inside the layer-structure of the moving web. The
second material layer (6) may comprise a second fiber layer or, for
example, a polymer coating. The laser marking could take place, for
example, by burning the surface of the fiber layer (1) or by
engraving it. Inside the layer structure, the marks (5) are
protected, but detectable with a detector to ensure the
authenticity of the material. The marked paper or board is suitable
for product packages to be protected against product forgeries.
Inventors: |
Miikki; Nina; (Imatra,
FI) ; Teva; Erkki; (Imatra, FI) ; Rasanen;
Jari; (Imatra, FI) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
Stora Enso Oyj
Helsinki
FI
|
Family ID: |
30129316 |
Appl. No.: |
10/585191 |
Filed: |
January 4, 2005 |
PCT Filed: |
January 4, 2005 |
PCT NO: |
PCT/FI05/00005 |
371 Date: |
September 14, 2007 |
Current U.S.
Class: |
162/129 ;
162/123; 162/132 |
Current CPC
Class: |
D21H 27/38 20130101;
D21H 21/40 20130101; B41M 5/26 20130101; B41M 5/24 20130101; D21H
25/005 20130101; D21H 25/04 20130101; B41M 7/0027 20130101; D21H
27/02 20130101 |
Class at
Publication: |
162/129 ;
162/123; 162/132 |
International
Class: |
D21H 27/30 20060101
D21H027/30; D21H 21/44 20060101 D21H021/44 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 5, 2004 |
FI |
20040006 |
Claims
1. A method for producing identification marks (5) in a
layer-structured paper or board (7) to be manufactured as a
continuous web, characterized in that the marks (5) are made with a
laser beam (4) on a moving web form fiber layer (1), on which a
second layer of material (6) is overlaid in such a way that the
marks remain inside the layer structure (7) of the moving web.
2. A method according to claim 1, characterized in that the marks
(5) are made by burning the surface of the fiber layer (1).
3. A method according to claim 1, characterized in that the marks
are made by engraving hollows (5') on the fiber layer (1).
4. A method according to claim 1, characterized in that the fiber
layer (1) contains mixing agent that is reacted or vaporized with a
laser beam (4).
5. A method according to claim 1, characterized in that after the
marking phase, the moving fiber layer (1) is laid against another
moving, web form fiber layer (6).
6. A method according to claim 5, characterized in that the marking
takes place with a paper or board machine as the fiber layer (1)
contains moisture originating from pulp, in which case the web (7)
is dried after the joining of the layers (1, 6).
7. A method according to claim 6, characterized in that the
materials of the fiber layers (1, 6) to be joined differ from one
another.
8. A method according to claim 7, characterized in that one fiber
layer to be joined is of chemical pulp and the other of mechanical
or chemical/mechanical pulp.
9. A method according to claim 7, characterized in that one of the
fiber layers to be joined is of unbleached pulp and the other of
bleached pulp.
10. A method according to claim 1, characterized in that the marked
web form fiber layer (1) is applied with a coating layer, covering
the marks (5).
11. Layer-structured paper or board (7) containing identification
marks that can be manufactured with a method according to claim 1,
characterized in that the web form paper or board (7) contains
marks (5) made with a laser beam and these marks are embedded
inside the layer-structure.
12. A paper or board according to claim 11, characterized in that
the web is rolled around a drum or core.
13. A layer-structured board (7) containing identification marks
that can be manufactured with a method according to claim 1,
characterized in that the board contains marks (5) made with a
laser beam, and the marks are embedded inside the structure formed
by a series of fiber layers (6, 1, 8) of the board.
14. Board according to claim 13, characterized in that the marks
are darker figures. (5) on the surface of the fiber layer (1), made
by the reaction induced with a laser beam.
15. Board according to claim 13, characterized in that the marks
are hollows (5') cut with a laser beam on the fiber layer (1) and
that these hollows are filled with a different type of material
present in the next fiber layer (6).
16. A board according to claim 14, characterized in that one of the
fiber layers is of chemical pulp and the other of mechanical or
chemical/mechanical pulp.
17. A board according to claim 13, characterized in that it is a
fold-carton formed of sulfate and CTMP layers.
Description
[0001] The invention involves a method for producing identification
marks on layered paper or board made in a continuous web. In
addition, the invention also concerns layered paper or board made
with this method, containing identification marks.
[0002] Visible marks can be made on consumer packages at the
packing phase, for the purpose of informing the consumer about the
packaging date or the "consume by" date of the product. In
addition, marks which may be partially or entirely invisible are
used as product identifiers, which identifies the origin of the
product and ensuring its authenticity.
[0003] Well-known package marking methods include ink printing,
embossings and cuttings or perforations made in the packaging
material by pressing or cutting. However, laser package marking is
used increasingly. With this method, the marks are made with a
laser beam without physically touching the packaging material or
leaving printing ink or any other extra substance on the
packaging.
[0004] With a laser beam, it is possible to affect fiber-based
material, such as paper or board, in a number of ways. As is
well-known, a laser beam burns through thin paper. To prevent this,
U.S. Pat. No. 6,306,493 presents a fine polymer additive to be
mixed in with the paper to act as absorbent and char, thus leaving
a dark, distinguishable mark on the paper. According to the
knowledge and experience of the applicant, it is, however, possible
to burn the surface fiber layer of the paper with a laser beam to
produce a mark, without any through-burning of the paper and
without the need to add polymer or other additives to the pulp, as
described in the publication.
[0005] Other possible fiber-layer laser working methods are cutting
the surface of the layer or engraving using an inert gas to prevent
the burning of the material. The marks made in this manner are
hollow on the surface of the fiber-layer, where no significant
material color alteration takes place. A mark can also be produced
by changing the structure of the fiber-layer by reacting one of its
components with a laser beam or by vaporizing it. The mark can be
detected so it can be used as an identifier.
[0006] A laser-marked paper or board similar to U.S. Pat. No.
6,306,493 has been put forward for use as packaging material,
labels or wrapping papers for various consumer packages marked by
targeting the laser beam on the surface of the material. The laser
marking is thus essentially related to the packaging process of the
products. U.S. Pat. No. 5,340,628 describes a laser-marked layered
packaging material where the paper base is introduced with a
polymer layer of polyester or polypropylene, which the laser beam
later penetrates, leaving a mark on the paper layer below. The
material was designed for labels attached to product packages where
the laser marks contain package-specific information about the
product.
[0007] According to the publications mentioned earlier, known
fiber-based laser-marked materials are meant mainly for making
marks serving consumers in the product packaging phase. Their
applicability is not the best possible to identifier marks to prove
the authenticity of the product, i.e. where the marking is mainly
intended to prevent or complicate product forgery. A forger who
copies the product with the package naturally tries to produce the
laser marks on the package.
[0008] The objective of the invention presented is to provide a
solution by marking paper or board used particularly as packaging
material with a suitable laser mark, which is significantly more
difficult to forge. The starting point of the invention is that in
the packaging phase instead of making marks on the ready-made
package or the package being manufactured, the mark is included in
the packaging material itself, in the paper or board, which is
layer-structured. Characteristic for the method according to the
invention is that the marks are made with a laser beam on a moving
web form layer, subsequently overlaid with a second layer of
material in such a way that the marks remain inside the
layer-structure of the moving web.
[0009] With this invention, identification marks are produced in a
moving web on an on-line principle with a paper or board machine or
with a paper or board coating unit. The laser heads can be located,
for example, in a stationary beam installed crosswise to the web,
which would produce a suitably covering regular figure in the
moving web. Any figure can be used as identification mark, for
example, a logo or a trademark of the paper or board manufacturer
or the product manufacturer, or, significantly, a mark specific to
the product being packaged. As the identification remains inside
the layer structure of the paper or board, it cannot be tampered
with or easily reproduced by a forger. To succeed, the forger would
need to copy the product and package including the packaging
material, which, even if technically possible, would make the
activity unprofitable.
[0010] The laser markings can be made by burning the surface of the
fiber layer by using a low power density CO.sub.2 laser beam. By
using a CO.sub.2 laser beam of higher power density and an inert
gas preventing oxidation hollows can be engraved by vaporizing
material from the fiber layer. The hollow relief works as
identification marks identified by a detector on raying.
[0011] The applications of the invention include a board containing
two or more overlaid fiber layers. The marks are created on the
surface of the web form fiber layer before the layers are joined
together. At the joining stage, the fiber webs may still be moist,
in which case the marks are made before the final drying of the
joint web with a board machine, and are inseparably integrated into
the final board. If the marks are hollows formed in the fiber
layer, moist or elastic fiber layers overlaid fill the hollows in
such a way that the board takes on an even thickness and density.
If different materials are used for the layers, the marks formed by
the hollows are still recognizable in the final board. If the
materials differ in darkness and the hollows were made in the
darker layer, the figures formed by the hollows can be seen (by
raying) in the board as lighter than the surrounding area.
Correspondingly the hollows made in the lighter layer show up as
darker than their surroundings. Chemical and chemical/mechanical or
mechanical pulps, and particularly unbleached pulps, such as brown
kraft pulp, and bleached pulps, have these kinds of darkness or
color differences sufficient for identification purposes.
[0012] In paper or board manufactured by the method used in the
invention, the material layer placed on the fiber layer and marked
online may be formed by a coating paste or glue layer, applied
during the manufacturing process with a paper or board machine, or
on a fiber layer, for example, by extruding the polymer coating to
be joined. With a transparent polymer coating the identification
marks can be left visible, for example, by burning, while at the
same time they are protected against being tampered with by the
coating. The identification marks and subsequent coating takes
place, according to the invention, as a continuous process without
interrupting the movement of the web.
[0013] With this method, products contain a paper or a board in the
form of a layered web containing identification marks, and the
paper or board is equipped with marks made by a laser beam that are
embedded inside the layer structure of the web. A marked product
such as this can be manufactured in large scale in a paper or board
factory, from where it is delivered in rolls to a customer who then
uses it for individual product packages. The material may be
multi-layered board, coated paper or board or polymer-coated paper
or board; and the marks may be hidden under the coating or a layer
of fiber, where they can be detected by raying or with a detector,
or the marks may be left visible under a transparent polymer
coating.
[0014] As an example of the application of the invention,
laser-marked packaging cartons may be made of a three-layered
folded carton form having outer pulp layers of sulfate and the
middle layer made of chemical-thermo-mechanic pulp (CTMP). In this
carton the marks are burned darker in the interface of the sulfate
and CTMP layers or the marks are hollows engraved in either layer,
detectable due to differences in the composition of the pulp.
[0015] The invention is explained in more detail below with
examples by reference to a drawing, depicting:
[0016] FIG. 1 the laser marking of a fiber material web and
subsequent joining to another web to produce a layer-structured web
format
[0017] FIG. 2 laser marking according to FIG. 1 and the joining of
the webs, seen from the side
[0018] FIG. 3 marking of the web as a III-III intersection of FIG.
2
[0019] FIG. 4 the layer structure of a laser-marked carton using
the invention
[0020] FIG. 5 the layer structure of another laser-marked
carton
[0021] FIG. 6 the layer structure of a third laser-marked
carton.
[0022] FIGS. 1-3 show the fiber material web 1; its route has been
introduced with a beam 2 in a crosswise direction to the web. From
the laser heads 3 beside the beam, identifying marks 5 are produced
on the surface of the web with the aligned laser beams 4. The marks
may be any FIG. 5, such as a company or product name, logo or
trademark, and in the case of FIG. 1 they form crosswise lines
spaced at even intervals on the web. The web should include enough
coverage for the marks 5 in such a way that there are enough marks
for each sheet or packaging preform later to be separated from the
layer-structured web.
[0023] The laser heads 3 in FIGS. 2 and 3 may comprise low-density
CO.sub.2 laser sources that lightly burn the surface of the web 1
in such a way that the identification marks 5 are darker areas
caused by the oxidation of the fiber material. Alternatively, with
higher density CO.sub.2 laser heads 3 and inert gas directed
simultaneously, the surface of the web 1 can be engraved with
hollows as identification marks, based on vaporizing the material.
It is also possible with laser beams 4 to cause the reaction or
vaporization of a component of the web material selectively from a
certain depth of the web or along the entire thickness of the web
in such a way that its density or composition is changed at the
place of marking.
[0024] After the marking phase, as the web 1 continues its
movement, another moving material web 6 is brought against it, as
shown in FIGS. 1 and 2, in such a way that together the webs form a
layer-structured, web format 7. Wherever necessary, adhesives can
be used to join the webs 1 and 6. The product 7 delivered as a
continuous web is rolled (not presented) and after further
converting phases--if any--it is delivered in the form of a roll,
sheets or preform to be used as individual product packages
containing identification marks 5.
[0025] Fiber material can also be used as the second web 6 to be
joined to the fiber material web 1 equipped with marks 5. In this
case, multilayered board is produced as the web form product 7. In
the schematic FIGS. 1 and 2, only two layers 1 and 6 are presented,
but boards may have more layers, and if needed, identification
marks 5 can be produced on the extra fiber layers or on the
opposite sides of the same layer.
[0026] The second material layer to be introduced on the marked
fiber material web 1 may also comprise, for example, a polymer
sheeting or a single- or multi-layered extruded polymer coating to
be laminated with the web. It is possible to laser-mark the fiber
material web 1 with a paper or board machine, in which case, in the
next phase the web is introduced with a coating paste covering the
identification marks.
[0027] When another fiber material web 6 is brought onto the fiber
marked material web 1, the identification marks 5 remain hidden
inside the obtained layer-structured board 7 from which the marks
however can be detected with a suitable device. If the layers are
thin enough, the marks 5 made by burning are visible to the naked
eye when the material is held up against the light. If the marked
fiber material web 1 is equipped with a transparent polymer
coating, the burned marks 5 can be seen through the polymer
layer.
[0028] FIG. 4 shows layer-structured products made using the
invention: a three-layer board 7, in which the middle layer 1 fiber
material differs from the fiber material of outer layers 6 and 8.
The material used for the middle layer could be, for example, CTMP
and the outer layers 6 and 8 could be, for example, bleached
sulfate pulp. The identification marks inside the layer-structure
are oxidations in the surface of the middle layer 1. The laser
marking of the middle layer 1 and join to the outer layer 6
covering the marks 5 take place as per FIGS. 1-3. The second outer
layer 8 may have been joined to the middle layer 1 before the
marking phase or after the phases described in the FIGS. 1-3.
[0029] The application of the invention according to FIG. 5 differs
from the one presented in FIG. 4: the marks in board 7 are hollows
5' formed on the surface of the middle layer 1. If the marking was
made with a board machine while the fiber material layers 1 and 6
were still moist, the hollows 5' fill with the material of the
outer layer 6 in such a way that the board 7 rendered as the final
product is essentially uniform in thickness and density. When the
materials of middle and outer layers 1, 6 differ, the marks formed
by the hollows 5' are still detectable using a detector. For
example, in one case, the CTMP may be darker than the sulfate pulp,
shown by raying as lighter than the surrounding area.
[0030] In the schematic 6, the identification marks 5'' are points
on the middle layer 1 where the material has been treated with a
laser beam throughout the entire thickness, for example, by
changing the material color or density. The change could be based,
for example, on the mixing component, such as polymer particles
oxidized by the laser beam, or a mixing component vaporized by
laser beam. Alternatively, the laser beam could be used to affect
only a part of the thickness of layer 1.
[0031] For professionals, clearly, many other examples of the
invention could be used. The relevant claims are set out below:
* * * * *