U.S. patent application number 13/085667 was filed with the patent office on 2011-10-13 for adhesive packaging.
Invention is credited to Ralf KALDENHOFF, Andreas ROBENS.
Application Number | 20110247304 13/085667 |
Document ID | / |
Family ID | 44009890 |
Filed Date | 2011-10-13 |
United States Patent
Application |
20110247304 |
Kind Code |
A1 |
KALDENHOFF; Ralf ; et
al. |
October 13, 2011 |
ADHESIVE PACKAGING
Abstract
A method for packaging hot melt adhesive, in particular sticky
hot melt adhesive or substances that are tacky at ambient
temperature as a material to be packaged in a plastic film,
comprising the steps: (a) fusing the material to be packaged; (b)
metering the fused material onto a cooling belt in portions and
cooling the material to below its fusion point; (c) removing the
material portions from the cooling belt, and (d) packaging the
material portions in the plastic film, the cooling belt having a
textile carrier with threads which form heat conducting threads
with which heat from the one flat side of the cooling belt can be
transferred to the opposite side, and the carrier being embedded
into a polymer matrix such that the heat conducting threads are
covered as far as possible, at least on the side coming into
contact with the material to be packaged.
Inventors: |
KALDENHOFF; Ralf; (Aachen,
DE) ; ROBENS; Andreas; (Krefeld, DE) |
Family ID: |
44009890 |
Appl. No.: |
13/085667 |
Filed: |
April 13, 2011 |
Current U.S.
Class: |
53/428 |
Current CPC
Class: |
B65B 63/08 20130101 |
Class at
Publication: |
53/428 |
International
Class: |
B65B 35/00 20060101
B65B035/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 13, 2010 |
DE |
10 2010 003 896.2 |
Claims
1. A method for packaging hot melt adhesive, in particular sticky
hot melt adhesive or substances that are tacky at ambient
temperature as a material to be packaged in a plastic film,
comprising the steps: (a) fusing the material to be packaged; (b)
metering the fused material onto a cooling belt in portions and
cooling the material to below its fusion point so as to form
material portions; (c) removing the material portions from the
cooling belt, and (d) packaging the material portions in the
plastic film, the cooling belt having a textile carrier with
threads at least part of which form heat conducting threads with
which heat from the one flat side of the cooling belt can be
transferred to the opposite side, and the carrier being embedded
into a polymer matrix such that the heat conducting threads are
covered as far as possible, at least on the side coming into
contact with the material to be packaged.
2. The method according to claim 1, characterised in that the heat
conducting threads of the cooling belt are made at least partially
of metals or metal alloys which are selected in particular from
carbon, iron, steel, copper, aluminium, silver, brass, bronze and
the like.
3. The method according to claim 1, characterised in that the
textile carrier comprises a fabric in plain weave in which the heat
conducting threads at least partially form warp threads.
4. The method according to claim 1, characterised in that the
textile carrier has weft threads or cross threads made of a
material selected from coated and/or non-coated polymer, carbon
and/or metal fibres, multifilaments or monofilaments.
5. The method according to claim 1, characterised in that the
polymer matrix is selected from elastic polyacrylate, silicone and
fluoro- and/or fluorosilicone elastomers.
6. The method according to claim 1, characterised in that at least
sections of the cooling belt are cooled on one or both sides by
means of a cooling device, preferably at least on the side which
lies opposite the side coming into contact with the material to be
packaged.
7. The method according to claim 1, characterised in that the
material to be packaged is sticky at ambient temperature, in
particular at 10.degree. C. or even at 0.degree. C., and the
material portions are preferably removed from the cooling belt in
the sticky state and packaged in the plastic film.
8. The method according to claim 1, characterised in that the
material to be packaged is a hot melt adhesive that contains a
polymer component which is selected from polyolefins, in particular
polyethylene, ethylene vinyl acetate copolymers, polyamides,
polyesters and polyester elastomers, polyurethanes and/or styrene
copolymers or block copolymers or mixtures of the latter.
9. The method according to claim 1, characterised in that the hot
melt adhesive contains auxiliary materials selected from
anti-foaming agents, wetting agents, colorants, stabilisers,
softening agents, preservatives and/or resins providing stickiness,
in particular colophony resins.
10. The method according to claim 1, characterised in that the
plastic film is suitable for fusing synchronously with the hot melt
adhesive and/or the plastic film has a fusion temperature of 25 to
100.degree. C., in particular 30 to 70.degree. C., preferably 35 to
65.degree. C.
11. The method according to claim 1, characterised in that the
plastic film contains polymers selected from polyethylene,
polyvinyl acetate, polyamides, polybutadiene, polyesters,
polycarbonates, atactic poly-alpha-olefins, thermoplastic
polyacrylamides, polyacrylonitriles, polymethylpentenes,
polyphenylene sulfides, aromatic polyurethanes, polystyrene
acrylonitriles, polyethylene terephthalates and co- and terpolymers
of the latter, in particular ethylene vinyl acetate.
12. The method according to claim 1, characterised in that the
plastic film comprises at least 5% by weight ethylene vinyl acetate
copolymer, for example more than 10% by weight, preferably more
than 25% by weight, particularly 35% by weight or more.
13. The method according to claim 1, characterised in that the
plastic film is provided as bags or a film tube and/or the plastic
film has a thickness of 5 to 200 .mu.m, in particular of 10 to 100
.mu.m.
14. The method according to claim 1, characterised in that the
plastic film is sealed after packaging the material portions and,
if so desired, the air is removed as far as possible while at the
same time shaking.
15. The method according to claim 1, characterised in that the
plastic film and/or the material portions have no surface treatment
with anti-adhesive substances, such as with silicone oils, tensides
or the like.
16. The method according to claim 2, characterised in that the
textile carrier comprises a fabric in plain weave in which the heat
conducting threads at least partially form warp threads.
17. The method according to claim 2, characterised in that the
textile carrier has weft threads or cross threads made of a
material selected from coated and/or non-coated polymer, carbon
and/or metal fibres, multifilaments or monofilaments.
18. The method according to claim 3, characterised in that the
textile carrier has weft threads or cross threads made of a
material selected from coated and/or non-coated polymer, carbon
and/or metal fibres, multifilaments or monofilaments.
19. The method according to claim 2, characterised in that the
polymer matrix is selected from elastic polyacrylate, silicone and
fluoro- and/or fluorosilicone elastomers.
20. The method according to claim 3, characterised in that the
polymer matrix is selected from elastic polyacrylate, silicone and
fluoro- and/or fluorosilicone elastomers.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS AND CLAIM TO PRIORITY
[0001] This application is related to application Ser. No. 10 2010
003 896.2, filed Apr. 13, 2010 in the Federal Republic of Germany,
the disclosure of which is incorporated herein by reference and to
which priority is claimed.
FIELD OF THE INVENTION
[0002] The present invention relates to a method for packaging hot
melt adhesive, in particular sticky hot melt adhesive or substances
that are tacky at ambient temperature as a material to be packaged
in a plastic film.
BACKGROUND OF THE INVENTION
[0003] Hot melt adhesives are solvent-free adhesives which for use
are brought, by applying heat, into a liquid or viscous state in
which they can moisten the material surfaces to be glued and to
which they adhere securely after cooling and setting. Hot melt
adhesives are generally made of a mixture of materials which during
production are fused together and then packaged.
[0004] For use as labelling adhesives or as contact adhesion
adhesives hot melt adhesives which have sticky properties at
ambient temperature or below are used. These adhesives are also
called PSA adhesives, and this stands for "Pressure Sensitive
Adhesive". The packaging and portioning of these sticky hot melt
adhesives gives rise to problems due to the tacky surface of the
adhesive portions.
[0005] Since in many cases it is desirable for the packaging of the
portioned hot melt adhesive also to fuse when used in order to
avoid additional working steps due to the emptying of the
packaging, the film materials used must have a low fusion point and
moreover must not appreciably worsen the adhesive properties of the
hot melt adhesive. When using film packaging made of polymers with
a low fusion point, due to the high fusion temperatures of the hot
melt adhesive of for example 120 or 140.degree. C., hot melt
adhesive which is introduced directly into the film packaging while
still hot separates.
[0006] In EP 0 649 718 a method is proposed according to which the
hot melt adhesive is packaged and the adhesive portions thus
obtained are surface-treated with an anti-adhesion substance,
cooled in a cooling bath and then packaged in foil bags.
[0007] In WO 00/34129 it is proposed to cool the sticky hot melt
adhesives after portioning in a water bath to such an extent that
they lose their stickiness and are packaged in this state.
Moreover, fatty acid derivatives are added to the water bath as an
anti-adhesion agent. It is a disadvantage with this method that in
this way one can only package PSA hot melt adhesives which already
lose their stickiness at temperatures above the freezing point of
the cooling bath, i.e. above 0.degree. C. With both of the methods
specified above the anti-adhesion agents used can, moreover, have a
disadvantageous effect upon the adhesive properties of the hot melt
adhesive. Finally, any water residue from the cooling path must be
removed from the hot melt adhesive prior to packaging in order to
rule out the presence of water when re-fusing the hot melt adhesive
prior to using it.
[0008] A further method for packaging hot melt adhesive is
described in DE 199 13 034, according to which the hot melt
adhesive is introduced directly into a film tube which is located
in a water bath during the filling process. In this way the outside
of the film tube is sufficiently cooled in order to prevent
immediate fusing due to the hot melt adhesive which has been poured
in and is still hot. Sections of the film bag are concertinaed by
means of transport rollers in order to form individual portions,
and are heat-sealed at these points. It is a disadvantage with this
method that the hot melt adhesive is only available in relatively
large portions, and that these portions must first of all be dried
after removal from the water bath. Furthermore, this method can
only be implemented with packaging films which have a relatively
high fusion point so that the latter do not fuse during filling
despite the cooling in water.
SUMMARY OF THE INVENTION
[0009] The object forming the basis of the present invention is to
provide a method by means of which the disadvantages known from the
prior art can be eliminated. In particular, one should be able to
dispense with the use of anti-adhesion surfaces coatings when
packaging sticky hot melt adhesives. Furthermore, complex drying
steps should be avoided, and it should be made possible to produce
different forms of administration and portion sizes for hot melt
adhesive portions.
[0010] The present object is achieved by a method of the type
specified at the start, which comprises the following steps: [0011]
(a) fusing the material to be packaged; [0012] (b) metering the
fused material onto a cooling belt in portions, and cooling the
material to below its fusion point so as to form material portions;
[0013] (c) removing the material portions from the cooling belt,
and [0014] (d) packaging the material portions in the plastic film,
the cooling belt having a textile carrier with threads at least
part of which form heat conducting threads with which heat from the
one flat side of the cooling belt can be transferred to the
opposite side, and the carrier being embedded into a polymer matrix
such that the heat conducting threads are covered as far as
possible, at least on the side coming into contact with the
material to be packaged.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0015] In order to fuse the hot melt adhesive the latter can be
used in any form or the hot melt adhesive can be mixed from its
individual components, i.e. be produced directly.
[0016] Production from the individual components can take place
before or during fusion. Here the fused material is advantageously
mixed by stirring, for example.
[0017] With the method according to the invention a plurality of
materials can be packaged, for example resins and the like, the
packaging of hot melt adhesives being a preferred application.
[0018] Within the framework of the method according to the
invention the metering in portions can take place in different
versions. For example, the fused material can be applied to the
cooling belt in strand form, in the form of cushions, or in
pastillated form. This can be implemented, for example, by means of
a heated extruder, by means of one or more nozzles, such as for
example in a pastillating device. Metering in portions is
understood to mean both metering in defined portions, for example
by weight, and metering in different portions. With portions of a
consistent weight the latter can be combined to forma desired
package size by counting. Portions of different weights can be
combined to form desired package sizes, for example by belt
weighers.
[0019] Within the framework of the present invention provision is
made such that the heat conducting threads are covered as far as
possible at least on the side coming into contact with the material
to be packaged. This is understood as meaning that the heat
conducting threads are covered practically entirely by the polymer
matrix, and can only stick out of the polymer matrix at individual
points, in particular the bend points e.g. with a plain weave of
the textile carrier. In such a case the coverage of the heat
conducting threads with the polymer matrix on the corresponding
side of the cooling belt is at least 75%, in particular at least 85
to 95%, preferably 95% to total coverage. Very particularly
preferably there is total coverage of the heat conducting threads
with the polymer matrix on at least one side of the cooling
belt.
[0020] One can also use cooling belts which have the aforementioned
coverage of the heat conducting threads with the polymer matrix on
both sides.
[0021] The heat conducting threads of the cooling belt enable rapid
conveyance of heat to the opposite side of the cooling belt so that
cooling of the material and of the hot melt adhesive by a cooling
bath, such as for example a water bath, is not required. On the
opposite side the heat discharged to here can be discharged for
example by direct contact with a cooling medium, such as by
spraying or indirectly by contact with a cooled plate or
roller.
[0022] By means of the almost total coverage of the heat conducting
threads with the polymer matrix of the cooling belt the heat
conducting threads, which are generally at least partially formed
from metal threads or carbon fibres, do not come directly into
contact with the material or hot melt adhesive. This is significant
in so far as, depending on the composition of the material of the
cooling threads, the hot melt adhesive can have an adhesion
capability of such a level that it is not possible in this case to
simply remove the adhesive portions from the cooling belt.
[0023] The cooling belts that can be used according to the
invention can advantageously be produced such that the textile
carrier is produced first of all, for example by interweaving warp
and weft threads into a plain weave. This textile carrier is then
passed through a V-shaped slot in which the raw material of the
polymer matrix is located which saturates the textile carrier.
Solutions or dispersions of the polymers of the polymer matrix in
water or organic solvents, for example, are used as a raw material
for the polymer matrix.
[0024] Likewise, reactive prepolymers can be used for the
production of the polymer matrix which after saturating the textile
carrier abreact, thus forming the polymer matrix. In principle all
reaction types, in particular radical polymerisation, polyaddition
or polycondensation, can be considered for the polymerisation
reaction taking place here, the latter for example with the
separation of water, methanol, ethanol, acetic acid or other
typical leaving groups. The substances specified above are known to
the person skilled in the art from the field of adhesives and joint
sealing compounds. Moreover, the polymerisation reaction can be
accelerated by irradiating with UV or IR light and/or by supplying
heat.
[0025] Therefore, a polymer matrix according to the invention can
be produced, for example, by hardening two-component silicone at
increased temperatures of approximately 200.degree. C.
[0026] Within the framework of the method according to the
invention the removal of the material portions from the cooling
belt prior to packaging is achieved, for example, simply by
discarding on a deflection roller. The discarding can additionally
be assisted by a scraper which does not necessarily have to, but
can touch the cooling belt surface. The polymer matrix of the
cooling belt and the scraper should advantageously be made of a
material to which the material does not or hardly adheres.
[0027] The selection of the material for the polymer matrix is
ultimately dependent upon the type of material or hot melt adhesive
to be packaged, and so the person skilled in the art can determine
appropriate polymer matrix materials by means of simple adhesion
trials. Silicone elastomers, fluoroelastomers and/or fluorosilicone
elastomers are particularly preferred as material for the polymer
matrix due to their anti-adhesive properties. The scraper can also
be produced from these materials or also from a sheet metal which
can be provided with these polymers or with a teflon layer.
[0028] Both the cooling belt and the scraper can be subjected to
corona or plasma treatment in order to further reduce the adhesion
of the material or the hot melt adhesive.
[0029] In an advantageous embodiment of the method according to the
invention the heat conducting threads of the cooling belt are made
at least partially of metals or metal alloys which are selected in
particular from iron, steel, copper, aluminium, silver, brass,
bronze and the like. It is also possible to use heat conducting
threads made of carbon. These materials provide the cooling belt on
the one hand with sufficient mechanical strength, and so
dimensional stability, and on the other hand have a high heat
conducting capability with which the heat of the fused material can
be discharged quickly from one side of the cooling belt to the
opposite side of the cooling belt.
[0030] In an advantageous embodiment of the method according to the
invention the textile carrier of the cooling belt comprises a
fabric in plain weave in which the heat conducting threads at least
partially form warp threads. This is advantageous since with a
fabric in plain weave the warp threads bend around the weft threads
so that the warp threads, and so the heat conducting threads,
define the upper and lower surface of the textile carrier. Despite
the integration into the polymer matrix the bending points of the
heat conducting threads are therefore located directly next to the
surfaces of the cooling belt, by means of which good head
conduction is achieved between the two flat sides of the cooling
belt. Other forms of the textile carrier are also possible, such as
a fabric in twill or satin weave. However, the carrier can also be
made of lattice weaves or knitted fabrics.
[0031] According to a further embodiment of the method according to
the invention the textile carrier has weft threads or cross threads
made of a material selected from coated and/or non-coated polymer,
carbon and/or metal fibres, multifilaments or monofilaments. Fibres
made of nylon, aramide, Kevlar, polyesters and the like, for
example, can be considered as polymer fibres. Suitable metal fibres
are made, for example, of iron, steel, copper, aluminium, silver,
brass, bronze or the like. Silicones, fluoro- and/or fluorosilicone
elastomers, for example, can be used for the coating of the
aforementioned fibres.
[0032] The warp and weft threads used within the framework of the
present invention can have core threads which are wrapped at least
by a wire or a polymer fibre. Alternatively, wires or polymer
fibres can be stranded or braided around the core threads. The
individual fibres of these threads can have a coating made of the
substances specified above. It is also possible to provide warp and
weft threads of the type specified above with a surface coating of
the substances specified above after the wrapping, stranding or
braiding.
[0033] Within the framework of the method according to the
invention provision can be made such that at least sections of the
cooling belt are cooled on one or both sides by means of a cooling
device, preferably at least on the side which lies opposite the
side coming into contact with the material or the hot melt
adhesive. Cooling rolls or a cooled plate, for example, can be
considered as a cooling device, over which the cooling belt is
passed and which can be cooled by means of cooling agents. The
opposite side can also be cooled by direct contact with a cooling
medium, such as for example by spraying. For this purpose an
appropriate spraying device for the cooling agent is provided.
Combinations of these cooling devices are also possible.
[0034] In an advantageous embodiment of the method according to the
invention the material or the hot melt adhesive is sticky at
ambient temperature, in particular at 10.degree. C. or even at
0.degree. C., and the material and adhesive portions are preferably
removed from the cooling belt in the sticky state and packaged in
the plastic film. Within the framework of the method according to
the invention it is therefore not necessary to cool the material or
the hot melt adhesive prior to packaging to such an extent that it
loses its sticky properties. For this reason, with the method
according to the invention hot melt adhesives which still have
sticky properties even at temperatures of below 0.degree. C., such
as for example at -5.degree. C., can also be portioned and
packaged. Here the individual adhesive portions can partially
sinter together after packaging. In this way on the one hand the
enlarged surface of the adhesive portions is obtained, which
enables rapid fusing. On the other hand, in this way less air
remains in the packaging and between the adhesive portions so that
space-saving packaging is guaranteed.
[0035] In a further embodiment of the present invention the
material to be packaged is a hot melt adhesive that contains a
polymer component which is selected from polyolefins, in particular
polyethylene, ethylene vinyl acetate copolymers, polyamides,
polyesters and polyester elastomers, polyurethanes, polyacrylates
and/or styrene copolymers or block copolymers or mixtures of the
latter.
[0036] Furthermore, the hot melt adhesive can contain auxiliary
materials selected from anti-foaming agents, wetting agents,
colorants, stabilisers, softening agents, preservatives and/or
resins providing stickiness, in particular colophony resins and/or
derivatives of the latter.
[0037] According to a particularly preferred embodiment of the
method according to the invention the plastic film is suitable for
fusing synchronously with the hot melt adhesive. For this purpose
the plastic film contains in particular polymers selected from
polyethylene, polyvinyl acetate, polyamides, polybutadiene,
polyesters, polycarbonates, atactic poly-alpha-olefins,
thermoplastic polyacrylamides, polyacrylonitriles,
polymethylpentenes, polyphenylene sulfides, aromatic polyurethanes,
polystyrene acrylonitriles, polyethylene terephthalates and co- and
terpolymers of the latter, in particular ethylene vinyl
acetate.
[0038] The plastic film used within the framework of the method
according to the invention preferably has a fusion temperature of
25 to 100.degree. C., in particular 30 to 70.degree. C., preferably
35 to 65.degree. C. The use of these films is particularly
advantageous because upon the fusion of the hot melt adhesive the
latter pass quickly into the liquid form, and so release the hot
melt adhesive packaged in the films for fusion. Plastic films with
these low fusion points can partially not be used with the methods
known thus far from the prior art because during packaging the hot
melt adhesive still has such a high temperature that the film
material is fused by this.
[0039] According to a preferred embodiment the plastic films used
comprise at least 5% by weight ethylene vinyl acetate copolymer,
for example more than 10% by weight, preferably more than 25% by
weight, particularly 35% by weight or more. The respectively
remaining portion is preferably formed from polyethylene.
Particularly suitable are mixed films of ethylene vinyl acetate
copolymer (EVA) and polyethylene (PE) with a mass ratio of ethylene
vinyl acetate to polyethylene of 5:95 to 50:50, particularly of
25:75 to 40:60, preferably of 35:65.
[0040] The vinyl acetate content in the ethylene vinyl acetate
copolymer used is advantageously at least 30 mole %, preferentially
at least 40 mole %, preferably 30 to 70 mole %, particularly
preferably from 40 to 60 mole %, very particularly preferably 50
mole %.
[0041] As well as low fusion points, these polymers and polymer
mixtures of ethylene vinyl acetate and polyethylene are
characterised above all by the fact that they do not generally have
any negative impact upon the adhesive properties of the hot melt
adhesive if the film material is fused and used together with the
hot melt adhesive.
[0042] The packaging of the material and hot melt adhesive portions
in the plastic film can be implemented in the simplest case by
wrapping or folding in. Preferably the plastic films used within
the framework of the present invention are, however, provided in
the form of bags or a film tube, it being possible to produce
individual bags from the latter by heat sealing and separating
after packaging the hot melt adhesive.
[0043] When packaging the material portions the plastic film is
generally sealed and, if so desired, the air is removed as far as
possible, this being realised, for example, by sucking out the air
while at the same time shaking. The closure is preferably
implemented by heat sealing because no additional auxiliary
materials such as clips and the like are required for this which
would interfere when (re-) fusing.
[0044] The plastic films used within the framework of the present
invention can in principle have any film thickness suitable for the
packaging of hot melt adhesives, for example a thickness of 5 to
200 .mu.m, in particular of 10 to 100 .mu.m.
[0045] Advantageously neither the plastic foil nor the material
portions have any surface treatment with anti-adhesive substances,
such as for example silicone oils, tensides and the like. Neither
is any adhesion-reducing surface treatment required, such as for
example corona or plasma treatment.
* * * * *