Note: Descriptions are shown in the official language in which they were submitted.
1
Tear-open strip for a packaging and method for producing a tear-open
strip
________________________________________________________________
DESCRIPTION:
The present invention relates to a tear-open strip for a packaging, to a
method for
producing such a tear-open strip as well as to a packaging with such a tear-
open
strip.
Tear-open strips for packagings are known from the prior art and serve for
facilitating opening of sealed packagings. However, tear-open strips are
presently
predominantly composed of plastic, which is problematic for environmental
protection and recycling reasons. Therefore, there were already first attempts
to
produce compostable or biodegradable tear-open strips on paper basis.
However, the circumstance is to be regarded as disadvantageous in these paper-
based tear-open strips that they exhibit a substantially inferior tear-open
behavior
than the previous plastic-based tear-open strips, since the paper-based tear-
open
strips often tear off upon tearing open and do not or only partially open the
packaging.
Therefore, it is the object of the present invention to provide a paper-based
tear-
open strip with improved tear-open behavior. A further object is in providing
a
method for producing such a tear-open strip. Finally, a further object is in
providing
a packaging with such a tear-open strip.
According to the invention, the objects are solved by a tear-open strip with
the
features of claim 1, a method for producing such a tear-open strip with the
features of claim 9 as well as by a packaging according to claim 15.
Advantageous configurations with convenient developments are described in the
dependent claims, wherein advantageous configurations of each inventive aspect
CA 03227170 2024- 1- 26
2
are to be regarded as advantageous configurations of the respectively other
inventive aspects.
A first aspect of the invention relates to a tear-open strip for a packaging,
comprising a layer system, which comprises a paper substrate and an adhesive
layer arranged on a first side of the paper substrate. According to the
invention,
an improved tear-open behavior is achieved in that the adhesive layer
comprises an uneven surface structure with relative elevations and relative
depressions at least in some regions. In other words, a paper-based tear-open
strip is provided according to the invention, the adhesive layer of which
comprises an uneven surface structure with relative elevations ("peaks") and
relative depressions (valleys, wells) in some regions or in complete manner.
Without wishing to be bound by this theory, the inventors assume that the
improved tear-open behavior is achieved by this uneven surface structure,
since
the tear-open strip can thereby be locally differently strongly adhered to an
associated packaging, since the depressions or valleys result in a local
weakening of the adherence, while the elevations or peaks result in a more
intimate firmly-bonded connection and thereby in a firmer adherence. Upon
tearing the packaging open, it is then prevented by the local weakenings of
the
adhesive connection that the paper-based tear-open strip too firmly adheres
and tears off. However, by the elevations, it is reliably prevented at the
same
time that an overall too weak adherence to the associated packaging would
occur. Preferably, the adhesive layer comprises between 20 and 100 elevations
per square centimeter of paper substrate. Between 40 and 60, in particular
about 50 elevations per square centimeter are particularly preferred.
Basically,
the adhesive layer can be composed of one or more suitable adhesives and
optionally contain additives. For example, an adhesive based on
poly(meth)acrylate, a natural or synthetic rubber and/or a sealing wax can be
employed. Generally "a/one" are to be read as indefinite articles within the
scope of this disclosure, thus always also as "at least a/at least one"
without
explicitly opposite indication. Conversely, "a/one" can also be understood as
"only a/only one".
CA 03227170 2024- 1- 26
3
In an advantageous configuration of the invention, it is provided that the
paper
substrate is compostable and/or biodegradable. Hereby, an improved
environmental balance is realized. Alternatively or additionally, it is
provided that
the paper substrate has a gramnnage between 80 g/m2 and 200 g/m2, in
particular between 100 g/m2 and 140 g/m2, in particular about 120 g/m2.
Hereby, a sufficient stability of the paper substrate and thereby an
advantageous sealing and tear-open behavior of the tear-open strip are
ensured for most of the application cases and embodiments. Particularly
preferably, the application amount of the adhesive per area unit of the paper
substrate is selected depending on or as a function of the grammage of the
paper substrate, wherein higher application amounts per area unit are
generally
selected for higher grammages. Hereby, a reliable closure of a packaging on
the one hand and a reliable tear-open behavior without premature tear-off or
tear-down of the tear-open strip on the other hand can be ensured.
Alternatively
or additionally, an advantageous sealing and tear-open behavior of the tear-
open strip is ensured in that the paper substrate has a stability of at least
75 N/15 mm, preferably of at least 110 N/15 mm in a main extension direction,
and/or a thickness between 100 pm and 250 pm, in particular between 150 pm
and 200 pm. By a main extension direction, the direction of the longest
extension of the tear-open strip is understood, that is usually the extension,
along which tearing open of the associated packaging is effected.
Further advantages arise in that the first and/or a second side of the paper
substrate is embossed and/or bleached and/or dyed and/or printed. Hereby, the
tear-open strip can be particularly simply optically and/or functionally
adapted to
different requirement profiles. For example, an embossed paper substrate can
effect a better nonstick characteristic of the non-adhering second side.
In a further advantageous configuration of the invention, it is provided that
the
adhesive layer is applied to the first side all over or in sections. In other
words, it
is provided that either the entire surface of the paper substrate is provided
with
CA 03227170 2024- 1- 26
4
the adhesive layer or only one or more surface regions. Hereby, the adhesive
and tear-open behavior can be controlled. Alternatively or additionally, an
advantageous tear-open behavior is achieved in that the adhesive layer has an
application weight between 15 g/m2 and 60 g/m2, in particular between 20 g/m2
and 30 g/m2. In further configuration, a particularly uniform tear-open
behavior is
achieved in that the adhesive layer has a regular surface structure, in
particular
a dot structure and/or a wave structure and/or a line structure and/or a
pyramid
structure and/or a truncated pyramid structure and/or a hexagonal structure
and/or a line structure with wells and/or a calotte structure. Thereby, the
elevations and depressions of the surface structure comprise regularly
arranged
structural elements, wherein only a single structural element type or two or
more structural element types can be provided. In case of multiple structural
element types, they can generally have identical or different volumes.
An additionally improved tear-open behavior arises in that the surface
structure
of the adhesive layer comprises a periodic structural element at least in some
regions, wherein at least one extension vector of the periodicity of the
structural
element is preferably arranged obliquely to the main extension direction of
the
paper substrate. In other words, it is provided that the extension vector of
the
periodicity of the structural element is not parallel or coaxially arranged,
but in
an angular position unequal to 00 and 180 , respectively, to the main
extension
direction of the paper substrate. Upon tearing the tear-open strip open,
forces
occurring therein are advantageously deflected and better distributed, whereby
a tear-off of the tear-open strip is particularly reliably prevented.
In a further advantageous configuration of the invention, it is provided that
a
separating layer is arranged all over or in sections on the second side of the
paper substrate, wherein an application weight of the separating layer is
preferably between 0.1 g/m2 and 2.0 g/m2, in particular between 0.2 g/m2 and
1.0 g/m2. Hereby, blocking or sticking of the tear-open strip to itself, for
example
in winding, can be reliably prevented. The separating layer can be formed
based on silicone, wherein other separating layers based on polyacrylate,
CA 03227170 2024- 1- 26
5
carbamate, polyvinyl ether wax or other suitable compounds as well as mixtures
hereof can basically also be provided.
Alternatively or additionally, it has proven to be advantageous that a
separating
strip is arranged on a side of the adhesive layer facing away from the paper
substrate. This too presents a possibility of preventing blocking or sticking
of the
tear-open strip to itself or undesired regions of an associated packaging. For
example, the separating strip can be a separating foil or a separating paper,
for
example a silicone paper.
In further configuration, an advantageous storage or an advantageous transport
of the tear-open strip is achieved in that it is rolled up on a reel with
preferably
traversing winding and/or is packaged as a flat reel.
A second aspect of the invention relates to a method for producing a tear-open
strip for a packaging, in which a layer system is produced in that an adhesive
layer is applied to a first side of a paper substrate. According to the
invention,
an improved tear-open behavior is achieved in that the adhesive layer is
produced with an uneven surface structure with relative elevations and
relative
depressions at least in some regions. The advantages resulting from it can be
taken from the descriptions of the first inventive aspect, wherein
advantageous
configurations of the first inventive aspect are to be regarded as
advantageous
configuration of the second inventive aspect. Conversely, advantageous
configurations of the second inventive aspect are also to be regarded as
advantageous configuration of the first inventive aspect. After its
production, the
tear-open strip can be reeled on reels with traversing winding, which allow a
large running length of up to 40,000 m or more, typically 10,000 - 20,000 m.
Alternatively, the tear-open strip can also be packaged as a flat reel.
In an advantageous configuration of the invention, it is provided that the
paper
substrate is provided with an uneven surface structure before applying the
adhesive layer and/or that the uneven surface structure is generated in the
CA 03227170 2024- 1- 26
6
adhesive layer. Thus, the uneven surface structure of the adhesive layer can
generally be achieved in that the adhesive layer itself is correspondingly
nonuniformly applied to a paper substrate with a surface uniform at least in
some regions. Alternatively or additionally, however, it can also be provided
that
the paper substrate is first provided with a nonuniform surface at least in
some
regions, whereafter the adhesive layer is uniformly or nonuniformly applied to
the paper substrate. Therein, the first side and/or the second side of the
paper
substrate can generally have a nonuniform surface. Therein, a smooth paper
substrate usually offers a simpler capability of coating than a rough or
structured one.
In a further advantageous configuration of the invention, it is provided that
the
adhesive layer is applied to the paper substrate by means of an anilox roll,
in
particular a hachure roll. This allows applying the adhesive layer to the
paper
substrate with a defined local dosage of the adhesive and thereby generating a
defined surface structure with predetermined elevations and depressions.
Besides the geometry of the structural element or elements, which form the
surface structure, the local application volume of the adhesive layer can also
be
precisely controlled by suitable choice of the wells and elevations,
respectively,
of the anilox roll.
Further advantages arise in that the paper substrate is provided with a
printing
layer and/or with a separating layer on a second side. With the aid of the
printing layer, the optical impression of the tear-open strip can be adapted.
Furthermore, the tear-open strip can hereby be provided with symbols or use
indications. The print can generally be effected in gravure printing,
flexographic
printing, offset printing, laser printing, inkjet printing or another suitable
printing
method. The printing ink can be based on nitrocellulose (NC), polyurethane
(PU), polyvinylchloride (PVC), polyvinyl butyral (PVB) or other binders. The
separating layer prevents undesired sticking of the tear-open strip for
example
to itself.
CA 03227170 2024- 1- 26
7
Therein, it has further proven to be advantageous if a varnish layer is
applied
between the printing layer and the separating layer since the printing layer
is
particularly simply protected from damage in this manner and can optionally be
provided with an additionally improved optical impression.
In that the tear-open strip is cut into multiple strips, preferably by means
of
scissors cut, the width of the tear-open strip can be adapted to different
application purposes, wherein the production of the tear-open strip can first
be
effected with a multiple of this width, which facilitates the coating process
or
processes for forming the layer system. Preferably, the tear-open strip has a
width between 2 mm and 15 mm, in particular between 4 mm and 8 mm, after
cutting.
A third aspect of the invention relates to a packaging, which includes at
least
one tear-open strip, which is formed according to the first inventive aspect
and/or is produced by means of a method according to the second inventive
aspect. The advantages resulting from it can be taken from the descriptions of
the first and second inventive aspects, wherein advantageous configurations of
the first and second inventive aspects are to be regarded as advantageous
configuration of the third inventive aspect. Conversely, advantageous
configurations of the third inventive aspect are also to be regarded as
advantageous configuration of the first and second inventive aspects.
Preferably, the packaging can be formed completely compostable or
biodegradable. Furthermore, the packaging can include two or more tear-open
strips.
Further features of the invention are apparent from the claims, the figures
and
the description of figures. The features and feature combinations mentioned
above in the description as well as the features and feature combinations
mentioned below in the description of figures and/or shown in the figures
alone
are usable not only in the respectively specified combination, but also in
other
combinations without departing from the scope of the invention. Thus,
implementations are also to be considered as encompassed and disclosed by
CA 03227170 2024- 1- 26
8
the invention, which are not explicitly shown in the figures and explained,
but
arise from and can be generated by separated feature combinations from the
explained implementations. Implementations and feature combinations are also
to be considered as disclosed, which thus do not comprise all of the features
of
an originally formulated independent claim. Moreover, implementations and
feature combinations are to be considered as disclosed, in particular by the
implementations set out above, which extend beyond or deviate from the
feature combinations set out in the relations of the claims. There shows:
Fig. 1 a schematic cross-section through a tear-open strip according to the
invention;
Fig. 2 a schematic and partial top view to the tear-open strip according to
the
invention during the application of an adhesive layer;
Fig. 3 a schematic perspective view of a tear-open strip reel;
Fig. 4 a top view of a packaging, on which the tear-open strip is arranged;
and
Fig. 5 an enlarged representation of the detail V shown in Fig. 4.
Fig. 1 shows a schematic cross-section through a tear-open strip 10 according
to
the invention. The tear-open strip 10 includes a layer system 12, which, in
the
present case, comprises a paper substrate 14, an adhesive layer 16 arranged
on a first side of the paper substrate 14 as well as a basically optional
separating layer 18 arranged on the second side of the paper substrate 14. One
recognizes in the cross-section that the adhesive layer 16 comprises an uneven
surface structure with a wave-like structure of relative elevations 20 and
relative
depressions 22.
The shown tear-open strip 10 is compostable and/or biodegradable. Generally,
the paper substrate 14 is formed based on cellulose. However, other paper
CA 03227170 2024- 1- 26
9
types, for example paper based on PET fibers, can also be provided. The
grammage of the paper substrates 14 is between 90 and 200 g/m2, for example
120 g/m2. The paper substrate 14 can be white or bleached or unbleached or
dyed. Similarly, it can be provided that the paper substrate 14 is printed on
one
side or on both sides. The paper substrate 14 has a high mechanical stability
in
the main extension direction H (see Fig. 2) or running direction of at least
75
N/15 mm, in particular of at least 110 N/15 mm or more. As one sees in Fig. 1,
the
paper substrate 14 is smooth to allow a good capability of coating. However,
it
can basically also be provided that the paper substrate 14 comprises a
structured surface on its first and/or second side, to which the adhesive
layer 16
and/or the separating layer 18 are applied. By embossing the paper substrate
14, a better nonstick characteristic of the non-adhering, second side can
often
be achieved.
In the present case, the adhesive layer 16 is applied to the first side of the
paper
substrate 14 all over, wherein only an application in some regions can
basically
also be provided. As one recognizes in Fig. 2, which shows a schematic and
partial top view to the tear-open strip 10 according to the invention during
the
application of the adhesive layer 16, the structured surface of the adhesive
layer
16 comprises a regular line or wave structure, which is formed by lines or
waves
formed by the elevations 20 as the structural elements. The shown wave or line
structure can for example be generated by means of a corresponding gravure of
a
coating cylinder, for example by means of a hachure roll. Furthermore, one
sees
in Fig. 2 that the line structure with the elevations 20 and depressions 22 is
regularly formed, since the lines periodically repeat themselves on the
surface of
the paper substrate 14. In addition, an extension vector V of the periodicity
of the
line structural element is arranged obliquely to the main extension direction
H of
the paper substrate 14. In other words, the lines or elevations 20 do not
extend
perpendicularly or parallel to the main extension direction H, but extend in
diagonal manner. However, other regular or irregular surface structures
(patterns)
can basically also be generated instead of line- or wave-shaped surface
structures.
CA 03227170 2024- 1- 26
10
For the adhesive layer 16, an adhesive based on polyacrylate, a natural or
synthetic rubber or a sealing wax can be employed. The adhesive application is
typically in the range between 15 and 60 g/m2, in particular at 20 to 30 g/m2.
The separating layer 18 can also be applied all over or only to certain
surface
regions of the paper substrate 14. The separating layer 18 is typically based
on
silicone, however, other separating agents, for example based on polyacrylate,
carbamate or polyvinyl ether wax, can generally also be used. The application
weight of the separating layer 18 is normally in the range between 0.1 and 2.0
g/m2, in particular between 0.2 and 1.0 g/m2.
Alternatively, the separating layer 18 can be omitted and the adhesive layer
16
can instead be covered with a separating foil (not shown) or a separating
paper,
for example a silicone paper.
Optionally, the paper substrate 14 can be printed, in particular on the non-
adhering side. If a separating layer 18 is provided, the print is preferably
directly
effected on the paper substrate 14 before coating with the separating layer
18.
The print can be effected in gravure printing, flexographic printing, offset
printing
or another printing method, The printing ink can be based on NC, PU, PVC, PVB
or other binders. Optionally, an additional varnish coating (not shown) can be
applied between the printing layer and the separating layer 18. In this case,
the
layer construction of the layer system 12 would be adhesive layer 16 - paper
substrate 14 - printing layer - varnish layer - separating layer 18.
Fig. 3 shows a schematic perspective view of a tear-open strip reel 26.
Hereto, the
tear-open strip 10 is wound to a core 24. Therein, the tear-open strip 10 is
preferably reeled with traversing winding, whereby a large running length of
up to
40,000 m, typically 10,000 to 20,000 m, is allowed. Alternatively, the tear-
open
strip 10 can also be packaged as a flat reel. The tear-open strip 10 can be
cut into
narrower strips. The typical strip width for the most usual packagings 28 is
about 2
CA 03227170 2024- 1- 26
11
to 15 mm, in particular 4 to 8 mm. Cutting is typically effected in scissors
cut,
however, other cutting or separating types are also possible.
Fig. 4 shows a top view of an unfolded packaging 28, on which a further
embodiment of the tear-open strip 10 according to the invention is arranged.
Fig. 4
is explained in synopsis with Fig. 5, which shows an enlarged representation
of
the detail V. One recognizes in particular in Fig. 5 that the adhesive layer
16 has a
regular dot pattern of dot-shaped elevations 20 and corresponding depressions
22
in the present case.
The parameter values specified in the documents for definition of process and
measurement conditions for characterizing specific characteristics of the
inventive
subject matter are to be regarded as encompassed by the scope of the invention
also within the scope of deviations - for example due to measurement errors,
system errors, weighing errors, DIN tolerances and the like.
CA 03227170 2024- 1- 26
12
LIST OF REFERENCE CHARACTERS:
Tear-open strip
5 12 layer system
14 paper substrate
16 adhesive layer
18 separating layer
elevations
10 22 depressions
24 core
26 tear-open strip reel
28 packaging
H main extension direction
15 V extension vector
CA 03227170 2024- 1- 26
