Note: Descriptions are shown in the official language in which they were submitted.
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CROSS FcEFERENCE TO RELATED APPLI CATION
This application claims the priority of Applications Ser.
No. P 41 17 931.5, filed May 31, 1g91, and P 41 21 024.7,
filed June 26~ 1991, in the Federal Republic of Germany, the
subject matter of which is incorporated herein by reference.
BACKGROUND OF_THE INVENTION
The present invention relates to a method of processing
plastic coated textiles, particularly plastic backed textile
floor covarings and ~or recovering the textile fibers and
plastics contained therein. The invention further relates to
a system for implementing this method.
Textile floor coverings that are backed with plastic are
employed, for example, as carpeting in living quarters,
offices and other buildings. They also find widespread use in
motor vehicles, particularly in passenger cars, but also in
busses and other public transporting means. Due to the
increasingly stricter rules for protection of the environment,
the manufacturers of, or dealers in, such floor coverings are
fre~uently obligated to take back the old coverings if a
corresponding article is newly purchased. Moreover,
considerable quantities of unusPd coverings are cut off along --
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the edges, due to cuttiny around obstacles and the like during
the production of such floor coverings. In every case it is
necessary to reprocess the existing remnant pieces and thereby
recover, as much as possible, the valuable textile fibers and
also the plastic material employed to back the coverings.
However, textile ~loor coverings of the described type
are not the only textile-plastic composite substances for
which a reprocessing task exlsts. Plastic covered tarps and
covers also are included in this task. In the past, it has
been the custom in such cases to simply burn the remnants
which, however, on the one hand, was a considerable stress on
the environment and, on the other hand, involved the
destruction of valuable raw materials.
SUMMARY OF THE INVENTION
To solve this problem, a method is proposed which is
composed of the following method steps:
- chopping the materials to be processed into
small chips, thus forming a pumpable substance;
- mixing the chips with water and comminuting
them in a mill, thus ~orming a pulp;
~ dewatering and drying the pulp;
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- mechanically separating the fiber; from the
resulting plastic granules.
In corresponding tests it has been observed that with
such a treatment it is possible to practically completely
separate the plastic particles from the fibers and cause the
plastic to aggregate into small granulate particles. After
the treatment, the textile fibers are available free from the
plastic in an aqueous suspension so that it is possible to
separate the two components ~after the pulp, that is, the
comminuted material, has been dewatered and dried. Such a
separation can bP accomplished in di~ferent ways, for example
by mechanically beating the mixture (simi]ar to thrashing) but
also by shaking it on screens or by blowing air over it.
In order to bring the material to be processed into a
form suitable for processing in comminutors, that is mills,
and forming a pulp, it is necessary to first break them into
small chips, in which case the chips should have a size that
is suitable to be stirred with water into a pumpable mixture.
In practical tests, a chip size of 5 x 5 to 10 x 10 mm2 has
~0 been found satisfactory. This size is here recommended with
preference although the implementation of the method is not
strictly bound to this size.
In the next process step, the chips are then further
comminuted in a miIl and form a pulp. Devlces known from the
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paper making industry, such as disc refiners or cone mills,
have been found to be acceptable mills. These mills operate
at a sufficient speed to be economical; on the other hand,
they also do not transfer any more energy to the material
being ground than is absolutely necessary for working; in
particular, the textile fibers are treated very gently during
their treatment in these mills, with the degree of working
being adjustable by varying the grinding gap.
The pulp resulting from the grinding is then dewatered
and finally dried completely. The then existing mixture of
textile fibers and plastic granulate can be separated into
fibers and granulate particles - as mentioned - by beating and
blowing. The fibers as well as the granulate particles are
reusable. The fibers may be processed, for example, into
coarse yarns which can a~ain be used for the manufacture of
floor coverings, but also for scrub rags and the like. The
granulate particles may be melted in a known manner in
extruders and can again be used as coatings. As is customary
in the plastics industry, the recycled granulate should not be
processed alone, rather these recycled materials should be
added in quantities of 20 to 40% to fresh granules so as to
obtain as the final product plastics that have the desired
quality characteristics.
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However, it i5 easier to reprocess the granulate
particles in heated mixers or heated stirrers.
If the fibers are composed o~ spinnable plastics,
particularly polyamide, they may be spun again once they have
been freed of the backing components. The advantage i5 here
that new, unmixed polyamide (or some other spinnable plastic)
is available again for reuse from which high quality yarns can
again be produced.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention also relates to a system for implementing
the method. This system will now be described in greater
detail with reference to the attached drawing figure. q'he
sole figure is a schematic representation of the system. The
description below is dependent upon the flow of the materials
to be processed.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The carpet sections to be processed are initially
transferred by way of a magnetic separator 1 to a feeder
conveyor ~. The maqnetia sep r~t r removes all magnetizable
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metal components from the material to be pro~essed and thus
protects the subsequent comminuting devices against damage.
From conveyor belt 2, the pieces travel into a chopping
device 3 that is equipped with longitudinal and transverse
cutters 4. In this device, the initially planar carpet pieces
are broken into small chips of a size suitable for further
processing. Their size is advantageously 5 x 5 to 10 x lo
mm2. The chips produced in this way now travel over conveying
means (not shown in detail) into intermediake containers 5, 5'
and 5''. The drawing shows three such intermediate
containers; the precise number depends of course on the size
of the system and is not critical.
From the intermediate containers, the chips can be
removed as desired and then travel to a subsequently arranged
dosing and transporting system 6. With the aid of this device
a predetermined quantity is conducted into a stirrer 7. The
stirrer is additionally supplied with water through conduits
8, 9 and 10. Water conduit 8 is here in communication with a
water reservoir 11 and may be supplied by way of a dosing pump
12.
In stirrer 7 a water-chips mixture is produced in this
way which is composed according to an accurate recipe. This
mlxture is conducted through a correspondingly dimensioned
ccndu~t 13 and check valves 14 and 15 tc a mill 16, for
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example a disc or cone refiner. This mill i~ driven with theaid of an electric motor 17 and comminutes the incoming chips
to such a degree that they form a pulp together with the water
that serves as the conveying means. The pulp may here be
circulated as required through valves 18 and 19 as long as
desired or it may be taken out of circulation through a valve
20 and a connected conduit 21. If necessary, water from
container 11 may be added through a valve 22. Depending on
the consistency of the materials to be comminuted, grinding
may be necessary for a longer period of time in which case the
chips-water mixture and the pulp resulting therefrom must be
circulated. In such cases it may be useful to include an
intermediate container (not shown in the drawing) in the
circulation system.
The finished pulp as it finally leaves through conduit 21
travels through a collection staga 23 to a screening device
24. The drawing shows here a longitudinal screening device
equipped with suction boxes 25. Instead of this longikudinal
screening device, a circular-screen dewatering machine may
also be employed.
The water extracted through suction boxes 25 travels
through a separator 26 to conduit 10 which selectively
conducts the clean water to stirrer 7 or to water container
11. If the latter is the case, a filter 27 may be connected
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in between. The air present in the separator is conducted
outside through a conduit 28 and an exhaust ~an 29.
The dewatered comminuted material travels from screeniny
device 24 to dryer 30 which is shown in the drawing as a belt
dryer e~uipped with a suction hood 31.. Instead of a belt
dryer, a drum dryer may also be employed to advantage.
Finally, the dry material~ which is now composed of a
mixture of textile fibers and pla5tic granules, reach~s a
separator 32 in which the fibers are separated from the
granules and are separately discharged through conduits 33 and
34.
The wet portion of the system may be rinsed out using
water container 11. In that way it can be ensured that ~ibers
of different compositions or fibers to be processed
1~ successively are not mixed with on~ another.
It will be understood that the above description of the
present invention is susceptible to various modifications,
changes and adaptations, and the same are intended to be
comprehended within the meaning and range of equivalents of
the appended claims.
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