Note: Descriptions are shown in the official language in which they were submitted.
. CA 022~7143 1998-12-01
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Co~v~yor belt for food
The invention relates to a conveyor belt for food,
especially for use in machines for food treatment, as is
applied e.g. in bakery mach;nes. In addition, the invention
is also to relate to cG--veyor belts used in machinec for
the processing or treatment of other foodstuffs in
industrial plants for processing sweets, meat, fish etc.
Using as an example the application of a conveyor belt in
bakery mach;nes for transporting dough pieces, e.g. in so-
called dough forming or dough cutting mach;nes, it is
common, according to the state of the art, to use co--veyor
belts made of cotton fabrics or cotton felts. The belts
have the task of receiving dough pieces from molds and
releasing them at interchange or release points. At the
release point with sharp rerouting, the dough pieces are
conveyed around rerouting knife edges with radiuses of
approximately 6 mm. A disadvantage of the cotton fabric or
cotton felt conveyor belts used up to now is that -
according to the consistency of the food parts to be
transported - they have an unsatisfactory detAç~h;lity at
the interchange points and also a disadvantageously large
amount of elongation of the cotton fabric conveyor belt
even after only several hours or days of use, which
eventually leads to the unserviceability of the belt.
Furthermore, rem~;n~srs of food sticking to the belt, e.g.
through oil, fat, sugar, blood, or compo~ents of meat and
fish, provide conditions enabling a bacterial invasion
which would be extremely critical with regard to hygiene.
The cotton material permeated with organic components of
the transported food provides a culture medium in which the
bacteria can settle lastingly and multiply. Thus, the
hygienic conditions for using such a co..v~yor belt in the
food sector are called into question or strongly
restricted. This further leads to a disintegration of the
.
CA 022~7143 1998-12-01
cellulose-contA;n;ng fibers due to bacterial infestation
and thus results in considerable losses in the strength of
the belt. In addition, cotton fabric col.-veyor belts without
binder equipment, especially those for bakery mach;nes,
must be produced individually for the particular machines
in guestion with regard to their length and width in
endless production. This production process is time-
consuming and expensive, for which reason the often
unsatisfactorily short life-time of such col~vayor belts is
considered to be a substantial disadvantage.
Based on this state of the art, it is the object of the
present invention to provide a considerably improved
cG..veyor belt for food, especially for use in mach;nes for
food treatment, which avoids the above mentioned
disadvantages and difficulties, has a considerably longer
life-time at lower production costs, prevents or strongly
reduces the settling or nesting of bacteria, and which,
especially when used in bakery machines, has a considerably
improved dough detachability and at least significantly
reduces harmful elongation during use.
This object is achieved according to the invention in a
conveyor belt of the kind stated above in that it contains
needle-p~nche~ web fabric impregnated with a binder
compound. Due to the velour-like well-closed surface and
the correspo~;ng considerably reduced dynamic friction
coefficient, the co.~-veyor belt according to the present
invention is, very advantageously, well able to receive and
release food parts and especially dough parts at
interchange points of the machine. Due to the method of
production with needle-p~nche~ web fabric, equipped with an
impregnation by a binder compound of a plastics
dispersion, a high inner strength of the cG.~veyor belt is
achieved while the elasticity is maintained, which
guarantees a low level of elongation of the material and a
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CA 022~7143 1998-12-01
long life-time. This can further be promoted by
incorporating a tension support in the form of a woven
fabric. Since the components of the cG~.veyor material -
fibers and binders - consist of plastics polymers, the
possibility of bacterial decomposition of the belt is
eliminated and the settling or nesting of bacteria on the
whole is reduced. This has a positive influence on the
hygienic conditions when applying or using such belts in
machines for food treatment. Furthsr~ore, this material can
be washed and disinfected with both acidic and alkaline
cle~n; ng agents.
In addition, the conveyor belt material can be produced as
rolled stock, on reels, i.e. the complicated production of
endless material can be avoided. The rolled stock can then,
;nexrsnsively and without long delivery periods, be used to
manufacture endless belts of individual length and width,
which can be made endless without a large effort e.g. by
finger splicing and/or gluing.
Thus, new areas of application can be opened in the food
processing industry by modifying the product according to
the present invention, not only in the field of bakery
machines, but also in any other fields of food processing,
e.g. in the processing of meat, sweets, c~nne~ fish, etc.
Due to its high strength and simultaneous high elasticity,
the co~-v~yor belt for food according to the invention can
be used without a problem in arrangements with knife-edge
belt rerouting, whereby small rerouting radiuses of e.g. up
to 6 mm can be used without a problem.
An effective embodiment provides that the impregnation is
preferably a full bath impregnation.
CA 022~7143 1998-12-01
This process is relatively uncomplicated and guarantees a
homogeneous distribution of the binder compound used for
impregnation in the material of the co.~vayor belt.
Advantageously, the needle-pllnche~ web fabric herein
consists of synthetic, natural and/or regenerated fibers
and preferably of PES (polyester).
The invention further provides that the binder compound
consists of natural and/or synthetic latex and especially
of a carboxylated butadiene-acrylonitrile copolymer, which
causes the hydrophilicity of the surface.
Effectively, the proportion of binder compound herein is
between 40 and 90 wt-%, preferably 75 wt-%. Accordingly,
the fiber proportion amounts to between 10 and 60 wt-%,
preferably 25 wt-%. The necessary characteristics with
regard to strength and elasticity can be adjusted in the
desired ~; n~ions by means of a balanced relation of
binder compound and fiber proportion, and of a fabric of
polyester monofilaments.
The invention further provides that the conveyor belt has a
characteristic tensile force of 2 2 N/mm at 1% elongation.
Advantageously, the surfaces of the con~eyor belt are
hydrophilic and at the same time permeable to air.
Furthermore, the col.~eyor belt is advantageously also made
resistant to oil, e.g. by a suitable choice of the
components. A largely well-closed surface can herewith be
achieved as a result of air-permeability, hydrophilicity
and elasticity, due to which the ability to receive and
release foodstuffs such as dough pieces at the interchange
points of the machine is significantly improved compared to
the state of the art. Especially using a fiber/binder ratio
of 1:3, a high inner strength of the co--veyor belt material
is achieved, which guarantees a low amount of elongation
CA 022~7143 1998-12-01
during use and a long life-time and at the same time
considerably reduces the rllnn;ng costs. Above all,
extremely disadvantageous delays due to failure of the belt
are avoided.
As suitable filling materials, the conveyor belt can
contain e.g. chalk, china clay, alumina and/or titanium
dioxide. Suitable color pigments can be of both organic and
inorganic nature.
The thickness of the col-ve~or belt is advantageously
between 1 and 3 mm, preferably 1.5 mm.
The present invention is explained in the following with
the help of an embodiment example:
Needle-punched web fabric, consisting of polyester fibers
with a weight per unit area of approximately 330 g/m2, full
bath impregnated in a foulard with an a~ueous binder
compound, consisting of carboxylated butadiene-
acrylonitrile copolymer, and cont~; n; ng filling material
and/or coloring pigments for coloration, is dried with a
binder dry add-on of 1000 g/m2 at temperatures of beL.~Qn
100 and 140~C. After the drying process, the preproduced
belt is emerized on both sides with corundum wheels,
preferably with a grain size distribution of 120, to a
final thickness of between 1 and 3 mm, preferably 1.5 mm.
The resulting velour-like smooth surface areas have largely
well-closed surfaces which are at the same time air-
permeable, hydrophilic and smooth and which have a dynamic
friction coefficient of ~ = 0.22.
The structure of the conveyor belt according to the present
invention comprises a needle-p~nc~e~ web fabric consisting
of 100% polyester fibers with a fiber titer of 1,7 dtex and
a staple length of preferably 40 mm, needled with a
needling density of 450 needle holes/cm2 and having a
CA 022~7143 1998-12-01
.
weight per unit area of e.g. 330 g/m2, and a woven fabric,
e.g. of polyester with 160 g/m2, full bath impregnated in a
foulard with an aqueous binder compound, consisting of e.g.
55 wt-% carboxylated butadiene-acrylonitrile copolymers, 42
wt-% chalk as filling material, 2.8 wt-% coloring pigments
for coloration, and 0.2 wt-% dispersing agents, with a
binder dry add-on of 1000 g/m2, emerized on both sides to
its final thickness after the drying process.
The completed co.veyor belt has the following
characteristics:
- a well-closed surface and thus avoidance of bacterial
attack and/or hypomycetes;
- air-permeability and thus impro-v~- -nt of the
detachability of the transported food parts;
- hydrophilic surface, promoting the drying process and
thus also improving det~c~hility;
- good cle~n;ng possibilities because belt can be washed
and disinfected;
- resistance to fat and oil;
- long-term thermal stability up to ca. 100~C;
- fulfillment of the legal norms for use in food
transport.
The conveyor belt according to the present invention
optimally achieves the object stated above.
