Note: Descriptions are shown in the official language in which they were submitted.
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A smart laminate and a smart container thereof
The present invention relates to a completely repulpable and recyclable
laminate as
defined below and a container, preferably a cup, based essentially on
cellulosic
material for water containing foodstuff formed of a laminate comprising
a) an optionally coated paper layer as optionally outside layer of the
container, having a weight of 100 - 350 g/m2,
b) an adjacent tie layer based on an at least repulpable, preferably
biodegradable adhesive having at least a water absorption capacity per
g/m2 over 24 hours allowing a Cobb value of up to 25 g/m2 (120 sec) of
layer c),
c) a moisture resistant liner paper with a weight of 30 - 45 g/m2 and
impregnated with a hydrophobing, at least repulpable, preferably
biodegradable agent to the extent that said impregnated liner paper has
a Cobb value of about 1 - 25 g/m2 (120 sec, DIN EN 20535: 1994)
d) a preferably heat sealing layer applied at least in the areas to be joined
for the formation of said container and based on an at least repulpable,
preferably biodegradable resin.
So called fast food restaurants are a major and growing supplier of nutrition.
Predominantly, the logical concept of fast food restaurants is based on the
single use
package. Single use means that after the consumption of the food, the package
of
the food is discarded.
Since such packages may consist of both cellulosic material, predominantly in
form of
fibres, like paper, paper board or other molded fibre items, or plastic
materials like
CONFIRMATION COPY
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polyethylene, polypropylene or polyethylenterephtalate or of a mixture of
cellulosic
material and plastic material, a waste management based on recycling the
material
could be difficult, even impossible.
Although it is known that the big advantage of single use package is that the
used
package need not be taken back for cleaning and thus a lot of energy
consumption,
like for heating dishwater and/or drying of the cleaned single use packages,
is
avoided, besides maintaining high and reliable hygienic standards for public
use, the
main stream of single use packages is worldwide a big problem.
The problem is related to the nature of the waste stream of single use
packages. As
already mentioned, this waste consists of a mixture of plastic material and
cellulosic
material typically. In order to recycle this waste, it is necessary to
separate the
different materials which could be recycled after separation from each other.
However, the waste stream containing a mixture of these materials makes it
often
impossible to separate and recycle the different materials economically.
Traditionally,
in the manufacture of paper and paper board, paraffin waxes and synthetic
polymers
as plastic material are used as moisture retardants, water repellents, oil
repellents,
stiffeness strengtheners and release agents. Consequently, the waste of such
paper
and paper board of which single use packages traditionally are made, is not
only
difficult, but often impossible to be repulped and recycled in standard paper
mill
processes, because the polymers, in particular the waxes derived from
petroleum,
are not biodegradable in mill white waters (circulated process waters) and
discharge
effluents. Additionally, the residue of the waxes that can't be removed from
the pulp
fibers during the repulping and recycling process can cause severe problems
due to
buildups that occurs on the screens and felts used during the process of
forming and
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making the paper or paperboard sheet. It is also known that such waxes resist
biodegradation and composting when disposed off in landfills and other waste
disposal systems. Consequently, paper and paper board coated or impregnated
with
traditional synthetic polymers and waxes are also difficult and often
impossible to
repulp and recycle owing to their resistance to separate from the fibres in
the
standard repulping processes resulting in significant fibre losses in efforts
to repulp
and thus recycle them. Moreover, such synthetic polymers are also not
biodegradable and therefore resist composting.
It is known that such impregnated paper and/or paper board can only be
repulped by
using specialized repulping machinery that separates the pulp fibres from the
laminated films and/or impregnation which is far more expensive in terms of
operating costs and/or recycled pulp fibre yields. The action of separating
the fibres
from any impregnating synthetic and/or plastic material damages some fibres
causing
them to be selected out of the recycled pulp and to be lost for reuse.
Additionally a
separated plastic material waste carries some of the fibres out of the
repulpate when
its adherence to the fibres is not hindered by the repulping process.
Likewise, not
only synthetic material used as laminates for the manufacture of paper and
paper
board, but also coatings and impregnating products made from synthetic
materials
like waxes, can be repulped for recycling only in specially configured
repulping
equipment that removes and separates the waxes. However, these more intense
physical and chemical requirements of these repulping processes coupled with a
loss
of fibres that become trapped in the wax cause the recyclable repulped fibre
levels to
fall far below those of the standard repulping processes. In addition,
packages made
from such products are not biodegradable and must be separated and deposited
in
separate landfill areas.
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It is therefore an object of the present invention to provide a material for a
container
and such container formed thereof, preferably for single use, based on
cellulosic
material for foodstuff containing water, which can be repulped and recycled
according
to the standard paper mill processes, whereby the residue, if any, is
preferably
biodegradable and can be composted when disposed off in a landfill or
otherwise
disposal systems besides allowing direct food contact.
This object is solved by providing a completely repulpable and recyclable
laminate
based essentially on cellulosic material, preferably for the formation of a
preferably
single use container for water containing foodstuff, which laminate comprises
a) an optionally coated paper layer as optionally outside layer of the
container, having a weight of 100 - 350 g/m2,
b) an adjacent tie layer based on an at least repulpable, preferably
biodegradable adhesive having at least a water absorption capacity per
g/m2 over 24 hours allowing at least a Cobb value of up to 25 g/m2
(120 sec, DIN EN 20535: 1994) of layer c),
c) a moisture resistant liner paper with a weight of 30 - 45 g/m2 and
impregnated with a hydrophobing, at least repulpable, preferably
biodegradable agent to the extent that said impregnated liner paper has
a Cobb value of about 1 - 25 g/m2 (120 sec, DIN EN 20535: 1994)
d) a preferably heat sealing layer applied at least to the areas which have
to be joined for the later formation of a container and based on an at
least repulpable, preferably biodegradable resin.
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Layer a) of the laminate, optionally the outside layer of a container formed
of the
inventive laminate, is an optionally coated paper layer having a weight of 100
- 350
g/m2, preferable a weight of 2_150 g/m2. This layer is preferably a paper
board, which
guarantees the required mechanical properties of an inventive container formed
of
the inventive laminate.
Preferably, such paper board used as outside layer a) contains already
recycled
fibres.
In addition, the surface of layer a) forming the outside surface of an
inventive
container formed of an inventive laminate can be coated with an at least
repulpable,
preferably biodegradable coating such as a clay coating, a polyvinylalcohol
coating or
a starchcoating, which coating is preferably at least water soluble or water
dispersable and therefore repulpable.
Usually, a coating gives a good surface for printing.
The outer layer a) of the inventive laminate is tied to the layer c), the
moisture
resistant liner paper, which becomes the innermost layer of a container formed
of an
inventive laminate, by means of a tie layer b).
The tie layer b) ties the outer layer a) preferable the paper board, to the
layer c)
based on liner paper.
Preferably, this tie layer b) is based on an at least repulpable, preferably
biodegradable and heat-activatable adhesive having a certain water absorption
capacity per g/m2 over 24 hours before losing its cohesion. In order that tie
layer b)
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can absorb a certain amount of water, the at least repulpable adhesive is
blended
with a water absorbing compound in an amount sufficient to achieve at least a
water
absorption capacity per g/m2 over 24 hours allowing a Cobb value of up to 25
g/m2
(120 sec determined according to DIN EN 20535: 1994) of layer c). Such a water
absorbing compound is an at least repulpable, preferably biodegradable,
natural or
synthetic compound.
As natural or partially natural compound with water absorption capacity one or
more
compounds with gel-building capacity selected from the group comprising
microcrystalline cellulose with 11 wt. % carboxymethylcellulose sodium,
carboxymethylcellulose sodium, locust bean flour, citrus pectin, starch,
alginate, guar
flour, iota-carrageenan, karaya gum, gellan gum, galactomannan, tara stone
flour,
apple pectin, lemon peel pectin, sodium hyaluronate, tragacanth, tara gum and
xanthan gum can be used, which compounds preferably are gelling compounds.
Preferably, as water absorbing compound an alginate like a natural, partially
natural
and/or synthetic alginate, preferable originating from algae, most preferably
from
brown algae can be blended with the at least repulpable adhesive.
As synthetic compounds with water absorption capacity super-absorbent resins,
preferably super-absorbent crosslinked polyacrylates, preferably sodium- or
ammonium-neutralized, can be used, which are at least repulpable, preferably
biodegradable.
The natural as well as the synthetic compounds with water absorption capacity
are
preferably provided as powder in order to be blended with the adhesive more
easily.
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Preferably, the preferably heat activatable adhesive blended with the water
absorbing
compound has a melting point ? 70 C and loses its cohesion after the mentioned
water absorption capacity has been exceeded. This kind of water buffering
property
of the tie layer allows that the liner paper as the inside layer c) of an
inventive
container formed of an inventive laminate to have a certain minimum water
permeability before losing its cohesion which is necessary to be repulpable.
Therefore, the moisture buffering ability of the tie layer is a precondition
to provide a
completely repulpable container, formed of the inventive laminate, although
foodstuff
containing water like beverages can be served in the inventive container,
preferably a
single use cup, formed of an inventive laminate.
Preferably, the preferably heat activatable adhesive is based on an at least
repulpable, preferably biodegradable resin, preferably an at least hot water
soluble
resin selected from the groups comprising polyethylenvinylalcohol,
polyacrylates like
polyethylacrylate, polypropylacrylate, polymethacrylates like
polyethylmethacrylate or
polypropylmethacrylate, polyacrylic acid, copolymers of acrylic acid like an
ethylene/acrylic-acid-copolymer, a ethylene/butylene/acrylic acid copolymer, a
butylene acrylic acid copolymer, methacrylic-acid copolymers like
ethylene/methacrylic-acid copolymer, polyethylene/vinylacetate and a mixture
thereof.
The weight of layer b) is preferably from 2 to 10 g/m2, more preferably 4 to 8
g/m2.
As already mentioned, in order to provide a completely repulpable and
recyclable
laminate respectively a completely repulpable and recyclable container, the
tie layer
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has to co-function with the layer c), which is the inner layer of the
container formed of
the inventive laminate and is in direct contact with the foodstuff containing
water.
This liner paper has a moisture resistant impregnation allowing a Cobb value
of 1 -
25 g/m2 (120 sec), preferably 10 - 15 g/m2 (120 sec), measured according to
DIN EN
20535:1994. The low water permeability is necessary in order to guarantee
repulpability of the inventive container formed of the inventive laminate
without losing
its cohesion in contact with water containing foodstuff. Because the tie layer
cooperates with layer c), the liner paper, by having at least a water
absorption
capacity per g/m2 over 24 hours allowing a Cobb value of up to 25 g/m2 (120
sec) for
layer c), a container can be used for food containing water and is also
repulpable
completely.
For hydrophobing the liner paper of layer c) an at least repulpable,
preferably
biodegradable hydrophobing agent is used in an amount to achieve the required
Cobb value. Preferably the hydrophobing agent is based on an at least
repulpable,
preferably biodegradable hydrogenated triglyceride or a blend of natural,
partially or
fully hydrogenated triglyceride is used. More preferably, the hydrogenated
triglyceride
is selected from the group comprising hydrogenated vegetable oil, preferably
soybean oil, peanut oil, olive oil, palm oil, coconut oil and/or cotton seed
oil, and an
animal fat preferably a beef tallow, pork lard, poultry grease and/or fish
oil. Most
preferably a vegetable oil is used.
The hydrogenated triglycerides have preferably a carbon-chain-length of 10 -
20.
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Contrary to waxes like paraffin waxes used traditionally for hydrophobing the
inner
layer of a preferably single use container for water containing foodstuff, the
hydrogenated triglycerides allow repulping at normal repulping conditions
according
to standard repulping processes. The hydrogenated triglyceride hydrophobing
impregnation can be easily removed with normal foam tank separation processes
because the triglyceride particles formed and dispersed in water during
repulping
then float on the cool water and are not attracted to the paper fibres.
Therefore, the
hydrogenated triglyceride particles can be easily separated from the paper
fibres,
which can be repulped, whereas the triglyceride particles can be biodegraded.
Accordingly, the use of hydrogenated triglyceride for impregnating and/or
coating
paper or paper board allow a repulping rate, equal to those of untreated paper
or
paperboard or any other kind of untreated cellulosic material.
It is also possible to use synthetic resins as hydrophobing agents for
impregnating
the inner liner paper like for instance the resin described in US 5,585,456,
which are
at least repulpable, cationic, thermosetting resins prepared by reacting a
polyamine
with a polycarboxylid acid or ester to form a polyamideamine, which is reacted
with a
dialdehyde and epichlorohydrine. According to the disclosure of this US
patent, this
hydrophobing resin allows repulping of the impregnated paper product when
subjected to standard repulping conditions.
Most preferably, hydrogenated triglycenides are used for the hydrophobing
impregnation.
The liner paper used in layer c) has a weight of 30 - 45 g/m2.
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Preferably, the liner paper is based on finely-ground wood-fibers. Most
preferably, the
liner paper consists entirely of materials from renewable sources.
It is evident that the liner paper as well as the hydrophobing agent and all
other
materials of which the inventive container is formed have to be allowed for
direct food
contact (as relevant to to-be-packed foodstuff).
The liner paper has to cover the entire inside of the container, preferably
including
any open edges at the inside of the container. Thus, the liner paper having
the above
described Cobb value can protect the adhesive layer b) and the outer layer a),
preferable made of paper board, from any direct contact with the contained
foodstuff
comprising water. Consequently, the tie layer b) cannot be dissolved by any
direct
contact with the contained foodstuff especially not with the water of the food
stuff.
In order to protect the inventive container built from an inventive laminate
from
environmental influences, especially moisture, during the handling, storage
and
utilization of such a container, it is possible that layer a) is protected by
a further layer
c) with the hydrophobing impregnation like-layer c), such a further layer with
a
hydrophobing impregnation, namely layer c'), can be tied to layer a) by means
of a
further tie layer, namely layer b') having also the already described water
absorption
capacity. This further layer c') will be preferably the outside layer of an
inventive
container formed from this inventive laminate.
Therefore, a further object of the present invention is completely repulpable
and
recyclable a laminate based essentially on cellulosic material, consisting of
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c') a moisture resistant liner paper as surface layer with a weight of 30 - 45
g/m2
and impregnated with a hydrophobing, at least repulpable, preferably
biodegradable agent to the extent that said impregnated liner paper has a
Cobb value of about 1 - 25 g/m2 (120 sec)
b') an adjacent tie layer based on an at least repulpable, preferably
biodegradable
adhesive having at least a water absorption capacity per g/m2 over 24 hours
allowing a Cobb value of up to 25 g/m2 (120 sec) of layer c')
a) a paper layer having a weight of 100 - 350 g/m2 combined with layer c') by
means of the tie layer b')
b) an adjacent tie layer based on an at least repulpable, preferably
biodegradable
adhesive having at least a water absorption capacity per g/m2 over 24 hours
allowing a Cobb value of up to 25 g/m2 (120 sec) of layer c)
c) a moisture resistant liner paper with a weight of 30 - 45 g/m2 and
impregnated
with a hydrophobing, at least repulpable, preferably biodegradable agent to
the
extent that said impregnated liner paper has a Cobb value of about 1 - 25 g/m2
(120 sec, DIN EN 20535:1994)
d) a preferably heat sealing layer applied at least in the areas which have to
be
joined for the later formation of a container and based on an at least
repulpable, preferably biodegradable resin.
The layer c') as well as layer b') are composed of the materials already
disclosed in
the present description for layer c) respectively layer b).
In order to form the inventive container, preferably a cup, especially for a
single use
from an inventive laminate, the laminate has preferably at least in the areas,
which
have to be joined for the formation of the container or as a complete layer
over the
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whole surface layer c) a preferably heat sealing layer d), which preferably
can be
activated by heat, preferably by hot air, to form a sealing bond. This heat
sealing
layer d) is preferably based on a at least repulpable, preferably
biodegradable,
thermoplastic resin with heat sealing properties such as
polyethylenvinylalcohols or
(meth)acrylic-acid copolymers. Therefore, the heat sealing layer d) is also
repulpable
and optionally recyclable.
Preferably, the heat sealing layer d) amounts to 8 - 20 g/m2, more preferably
to 10 to
16 g/m2, and is preferably applied by coating, whereby for joining the parts
of the
laminate to form the inventive container, the joining regions are activated by
heating,
preferably by means of hot air, and combined by pressing.
A further object of the present invention is a completely repulpable and
recyclable
container, preferably a cup, based essentially on cellulosic material for
water
containing foodstuff formed of an inventive laminate comprising layers a) to
d),
whereof layer a) is the outside layer of the inventive container, preferably a
single use
cup.
A further embodiment of the present invention relates completely repulpable
and
recyclable container, preferably a cup, more preferably a single use cup based
essentially on cellulosic material for water containing foodstuff formed of an
inventive
laminate consisting of layers c'), b') and layers a) to layer d).
According to the present invention the term "Completely repulpable and
recyclable"
means that the whole contents of cellulosic material of the inventive
container is
repulpable and recyclable and the contents of non-cellulosic material is at
least
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repulpable according to standard paper mill processes with standard process
conditions without relying on any specially configured repulping equipment.
The non-cellulosic material of the inventive container which is at least
repulpable
according to the before described definition, is water dispersable or water
soluble.
Therefore, it can not only be repulped, but also at least partially be
recycled into
standard paper manufacturing processes or be degraded biologically according
to
DIN EN 13432.
The amount of non-cellulosic material of an inventive laminate respectively of
an
inventive container is at most 15 % by weight, preferably at most 2,5 % by
weight of
the whole laminate or container, the higher value depending whether the free
surface
of layer a) is coated and on which material such coating is based.
The inventive laminates can be produced according to known manufacturing
processes preferably by laminating and/or coating and/or extrusion.
Preferably, the tying of layer a) to layer c), respectively to layer c') can
be carried out
by activating the activatable adhesive of layer b) respectively b') by hot air
or
ultrasonic application.
This is also possible for sealing the regions of an inventive laminate to be
joined for
the formation of an inventive container.
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The inventive container, especially the inventive, preferably single-use cup,
can be
produced according to the following process, which preferably can be carried
out
continuously.
In describing this process, it is referred especially to the enclosed Figures
1 A - 1 G of
which
Figure 1 A shows the first production step,
Figure 1 B shows the third production step,
Figure 1 C shows the fourth production step,
Figure 1 E shows the sixths production step, and
Figure 1 F shows an inventive cup.
Figure 1 G shows a sectional view of an enlarged scale of the joining region
of the
produced cup according to figure 1 F.
The preferred method of producing an inventive container, in particular a cup
20, by
referring to these figures comprises the following steps:
punching a slit 12 in a first web 11 of paper board as outside layer a) of the
inventive container,
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- coating either the first web 11 or the second web 13 with an at least
repulpable, preferably biodegradable adhesive blend as tie layer b) and heat
activating the tie layer b) by means of hot air,
- combining the first web 11 with a second web 13 of moisture resistant liner
paper as impregnated layer c), such second web 13 covering the slit 12,
- coating the liner paper as layer c) with a preferably heat sealable layer d)
- punching the side wall part 14 out of the obtained laminate 10, the
dimension
of the side wall part 14 defining a conical or cylindrical shape of the
inventive
container, in particular the cup 20, with two lateral edges 15, 16,
- removing the side wall part 14 from the laminate 10, the liner paper 13
projecting beyond the paper board 11 in the region of the former slit 12 and
forming a tap 17,
- producing an edge protection in the region of the lateral edges 15, 16, the
tap
17 being laid around an end region of the paper board 11, and
- shaping the side wall part 14 to the side wall (sleeve) of the container, in
particular the cup 20, the two lateral edges 15, 16 being brought together in
an
overlapping manner and joined after having heated the heat sealing layer d) in
the joint regions and pressed together,
- inserting the bottom of the container, in particular of the cup 20, into the
side
wall (sleeve) from below.
In Fig. 1G, which is a diagrammatic view, not to scale, of the joining site
with edge
protection, it will be seen that the lateral edge 15 is guided past and behind
the
lateral edge 16 having the tab 17, and the tab 17 has been folded or turned
backwards as edge protection. A new lateral edge, which is here denoted by the
reference number 18, is thereby formed. By the turning or folding over of the
tab 17,
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which is produced from the material of the second web 13, the liner paper, the
lateral
edge is protected against the penetration of moisture. This is essential
because the
lateral edge 18 comes into contact with the liquid stored inside the paper cup
20.
The edge protection is distinguished by the fact that the tab 17, which
consists of the
liner paper as the second web, is guided around a lateral edge and thereby
depicts a
180-degree change in direction.
Preferably the bottom of the inventive container, in particular of the cup 20,
is also
formed, preferably punched out of an inventive laminate.
It is obvious for a person-skilled-in-the-art that the inventive container,
especially a
single used cup, can also be produced according to other known manufacturing
processes.
Additionally, it is evident that the inventive laminate can also be used to
produce
other containers, especially for single use, than cups like trays and
optionally
corresponding lids, packages for milk or juices, plates or folding cartons for
frozen
foodstuff. All these kinds of containers are especially suitable for single
use.
