Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Process for Treatinq ~aterials Joined to One Anothèr By Adhesion
Promoter
The invention relates to a process for treating at least two
materials joined to one another by adhesion promoter. Such
materials can be, e.g., cable sheathings or parts of cable
sheathings, in which essentially polyethylene and aluminum are
~oined to one another by an adhesion promoter. But, e.g., -
aluminum blister packs or toothpaste tubes or similar things can
also be involved here, in which, such as, e.g., in the case of
aluminum blisters, essentially aluminum and plastics, such as
polypropylene or PVC, are joined to one another by an adhesion
promoter. The treatment of these materials, once they have
fulfilled their purpose, now consists of disposing of them or
burning them. If they are disposed of, a considerable need for a
disposal site develops, and simultaneously it must be accepted
that such materials do not decompose in the foreseeable future
but remain intact. But if they are burned, a considerable ;~
expense is required to make harmless the harmful waste gases
developing in this case. If the plastic portions are PVC,
additional measures must be taken in the incinerator to
neutralize the waste gas flows forming hydrochloric acid or to
make it harmless in any other way.
Processes for separating compound materials are already
known from the prior art. Such a process using a chlorinated
organic solvent, e.g., methylene chloride, chloroform or carbon
tetrachloride, and subceuqent azeotropic distillation is
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described in publication US-PS 4,543,346. A mixture of methanol
and methylene chloride is used in the process to separate
polyester and/or polyvinyl material disclosed anonymously 24520
in Research Disclosure, Vol. 245, p. 430. JP-A-60 212 434
tChemical Abstract, Vol. 104, No. 14, 111021 t3 also describes
organic solvents or mixtures, but which are free of water.
Drawbacks of these previously known mixtures or pure ~;-
solvents to be cited are relatively many plastics and dyes -~
dissolve in solvents and thus the solution must be worked up or
replaced more often than desired.
Starting from this situation, the invention is based on the
object to propose a process of the initially described type, with
which the disposal site require~ent is at least reduced and the
problems of combustion are avoided and the solvent mixture used
is suitable for treating maximum amounts of compound material
without being purified or replaced.
This object is achieved in a process of the initially
described type in that the adhesion promoter is dissolved by an
acetone-water mixture that does not dissolve the materials
themselves and as a result the materials joined to one another
are separated from one another. If the adhesion promoter is
dissolved, the elements of the materials previously joined to one
another are present individually and can be easily separated and
recycled. But if they can be simply recycled, a disposal site is
no longer necessary nor an incineration. Thus, the expenses for
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¦ a space for a disposal site are saved and the problems with the
incinexation are avoided.
In an embodiment of the proce s, it i8 proposed to spray the
crushed materials with the solvent or to immerse them in the
solvent. Thiis is in each case a very simple method with respect
to the course of the process to bring the solvent into contact
with the adhesion promoter. Simultan-ously, the already
dissolved adhesion promoter ~ 8 separated as a result also in a
simple manner, so that the dissolution process is accelerated.
Preferably, the material to be separated is crushed, and the
piece size of the crushed material i~ up to 10 cm2. As a result,
a large surface is provided at the edges on which the ~olvent can
reach the adhesion promoter more quickly. The solvsnt can then
quickly penetrate the adhesion promoter from several sides and
dissolve the latter. m e penetration depth, in this case, can be
relatively small, nevertheless a quick and complete detaching can
take place.
If, on the other hand, greater piece sizes are selected, the
later separation of the components can possibly be facilitated.
Thus, for example, usual pharmaceutical agent blisters can also
be processed without crushi~g.
The materials separated from one another by dissolution of
the adhesion promoter can now be separated by material groups.
Thus, it i8 useful to separate,-for example, an aluminum portion
from a plastic portion, but also to separate further the plastic ;
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portion once more into a PVC portion and "non-~VC portion." As a
result, the further recycling is considera~ly simplified. In
thifi case, it can be achieved, for example, in the float-sink
process that plastic portions float and aluminum portions sink.
The floating plastic portions can then be skimmed off or screened
out.
In addition, it is then also proposed that before the
archimedean separation, the materials separated froM one another
be removed from the solvent. on the one hand, the separation of
plastics and metal is, of course, very easily possible by this
above-mentioned archimedean separation. On the other hand,
however, the plastic portions can also be separated from one
another according to this principle. But in this case, only a
separation of the plastics into PVC and non-PVC portions is
important. Such a separation is possible problem-free because of
the clearly different specific weights of the above-mentioned
plastic groups.
Further possibilities of the material separation are, for
example, the hydrocyclone technique or air separation.
It is advantageous, of course, to move the crushed materials
and the solvent relative to one another. This can take place,
for example, by simple stirring, but also by recycling the
solvent. As a result, on the-one hand, the washing off of
already dissolved portions of the adhesion promoter is
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accelerated and shearing forces are exerted by the mechanical
stress, which also support the detaching process.
In addition, it is also proposed that the materials
separated from one another be purified by the solvent. This can
take place, for example, by drying. The materials separated from
one another are then present larg~ly residue-free f'or a further
treatment.
The materials separated from one another can exhibit, on
their part, still other co~tings, surfac0s or varnishings also on
their respective exteriors. The elements of the materials
separated from one another can thus be easily subjected to a
further treatment to remove such layers.
The most important feature of the acetone-water mixture is
that it dissolves out only the adhesion promoter, and plastic as
well as aluminum remain largely unchanged.
Depending on the desired quality of the recovered products,
it is possible that other chemical components, such as printing
inks, varnishes and adhesion promoters, are detached especially
from plastic and remain in the solvent to obtain the purest
possible substances and thuc to achieve a high value added. The
solvent must then be purified again from the dissolved substances
by distillation either in the process itself or else by a certain
number of process steps. In this case, the remaining low
distillation residue is the sole residual substance accumulating
in the process, which must be disposed of.
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An acetone-water mixture, containing 1-20% by weight of
water, has proven itself as a suitable solvent mixture. The
solvent mixtures have the advantage that the detachment
properties can be set pinpointed and variably depending on the
mixing ratio. Acetone-containing ~olvent ~ixtures are further
distinguished by rela~ively low toxicity as well as a good drying
behavior (high vapor pressure of the acetone) of the PVC swollen
with acetone.
It is possible with the process according to the invention,
in a very simple way, to separate from one another materials that
are especially flexible and joined to one another by an adhesion
promoter by dissolving the adhesion promoter and thus to make
recycling available. As a result, raw materials are saved, and
the burden on incinerators and disposal sit~s is relieved.
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Example 1
5 grams of pharmaceutical agent blisters are covered with 40
g of a solvent mixture made of 90% acetone and 10~ water in a 250
ml beaker and allowed to stand. After 80 minutes, the PVC has
completely separated from the aluminum and the solvent mixture i~
then decanted. Aluminum and PVC are dried in a forced-air drying
oven at 50C and then separated pure grade from one another by
alr s aration.
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