Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Process of treating scrap or waste product containing solid...
Reexamination Certificate
1999-07-29
2001-08-14
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Process of treating scrap or waste product containing solid...
C521S041000, C521S046000, C521S048000
Reexamination Certificate
active
06274637
ABSTRACT:
The patent application relates to a process for the recycling and/or production of plastics or new plastics mixtures and materials using new, reprocessed or used plastics and plastics mixtures and sorted and unsorted plastics wastes, in which the degree of grade purity and type identity of the plastics is not predetermined.
Of the large quantities of plastics of many different types produced each year, much, after being used in each case for the intended purpose, is finally dumped on landfill sites, thermally disposed of in refuse incinerators and therefore removed from the material cycle. The circumstances appear to be similar in the case of other materials. In the process, a large quantity of valuable, reusable materials is also lost.
The production and utilization of so-called materials from waste products has been on the increase for quite a long time. For example, in many places separate collection and/or sorting of different waste materials is advocated and carried out, since the reprocessing and recovery of the valuable materials contained therein or the production of materials obtainable therefrom is cheaper than with refuse or waste mixtures of random composition. The upshot is that the household and industrial refuse produced daily can be seen as “raw material”, but in individual cases the lack of type purity entails considerable problems. This is particularly true for plastics recycling.
Up to now it has been impossible to utilize mixed plastics wastes as materials if the differences in the plastics exceed a certain degree (see A. Jungbauer, Recycling von Kunststoffen, 1st Edition, Würzburg, Vogel-Verlag, 1994, in particular p. 40 et seq.). For this reason, it has been essential up to now to separate mixed plastics fractions cleanly into the respective grade- and type-pure plastics and then forward these sorted fractions to the respective recycling processes suitable for them. At most, mixtures of identical or very similar plastics materials have been tolerable. Such refuse sorting, in particular plastics refuse sorting, is labour- and cost-intensive however, with the result that the recycling processes or the products produced using the materials obtained in each case are comparatively expensive. The sorting of plastics wastes in household and industrial refuse is known to be problematical, and feasible only with difficulty or to a limited degree.
The composition of the plastics wastes in household and industrial refuse is extremely variable and can consist of several dozens of different plastic types and grades, the current state of knowledge indicating that the composition of the plastics wastes can be wholly different from region to region. It is assumed that on average the following types of plastics are found:
Polyethylene (LDPE, MDPE and HDPE)
ca 30%
Polypropylene PP
ca 10%
Polyvinyl chloride (PVC)
ca 15%
Polystyrenes (PS, EPS, ABS, ASA)
ca 15%
Polyamide (PA 6, PA 6, 6 etc)
ca 10%
Other industrial thermoplasts
ca 10%
Thermosets and composites
ca 10%
All of these are seriously contaminated by dye residues, paper, adhesive residues, coatings and other substances. The separation of such complex mixtures is often impossible even if the cost is reasonable.
Up to now, however, cleanness and type and grade purity have been essential for a high-grade recycling of these plastics. Mixed plastics wastes can be used to a limited extent only in low-grade applications. However, as explained above, any mixing of plastics types makes processing into high-quality products difficult and expensive or even impossible. Mixing with particular plastic types such as for example PVC actually makes recycling almost impossible.
It was therefore the object of the invention to provide a possibility of reprocessing, and in particular a process for recycling and utilizing, mixtures containing plastics waste or for utilizing newly produced plastics and preferably simultaneously a process for producing a new material using such newly produced or used plastics, in which grade purity and type purity of the plastics is not necessary and yet high-quality materials and products can be produced. This recycling process is also to be considerably cheaper than the previous processes and simultaneously also be able to include the simultaneous utilization of other waste materials.
This object is achieved according to the invention by a process for the production of a material from mixtures which comprise newly produced plastics material or plastics waste material (i.e. using new plastics or recycling used or other waste plastics), in which
a) a carrier material A, which comprises a newly produced plastics material or plastics waste material containing a uniform type-pure plastic or plastics of various types, a material of any or unknown composition X and an additional component Z selected from fatty acids, mixtures containing fatty acid, fatty acid derivatives which release fatty acid under the process conditions and fatty alcohols are mixed together, A and X together containing, relative to the volume, at least a quantity of plastics such that the non-plastics components are incorporated therein while a homogeneous or partially homogeneous composition is still forming,
b) this mixture is conveyed through a conveying device with constant mechanical mixing, kneading or compression, and is subjected along the transport path to a sectional multistage thermal treatment, the temperatures in the various stages lying in each case independently of one another in a range from 60° C. to 400° C., and
c) the thermally treated mixture is discharged via a nozzle for further treatment or for shaping.
Preferred embodiments are the subject of the sub-claims.
When the process according to the invention is used, it is surprisingly possible to process waste and refuse which contains several different and even considerably different kinds and types of plastics. Furthermore, the plastics compositions produced can unexpectedly be processed into high-quality products, and the quality and the resulting useful life achieved when using recycled plastics, as against when using newly produced plastics, can now surprisingly be increased to ca 80% and more instead of the previous ca 30 to 35%.
This recycling and production process makes it possible in particular for plastics and plastics grades of all types of plastics (thermoplasts, thermosets, elastomers and others), some of which according to current knowledge are considered to be non-recyclable, non-remeltable, incompatible with each other when mixed, and not homogeneously miscible, to form a homogeneous or partially homogeneous composition by thermal-mechanical treatment during processing and through the use of an admixed additional component.
The incompatibilities occurring hitherto in the known processes between the different plastics (e.g. PVC in any combination, PS/PE, PE/PP, PA/PE) and the decomposition or combustion of the obtained plastic compositions on heating are overcome by the process according to the invention. What is particularly noteworthy is that the various plastics can be processed unsorted (not type-pure), i.e. together.
Moreover, many other waste materials such as for example rubber, carpets and floor coverings, wood wastes, glass fibre wastes, waste paper etc can be added to the process as an additional constituent of the material of any or unknown composition X and be disposed of without the effectiveness of the process being detrimentally impaired. An important contribution is therefore made overall to the avoidance of refuse that has to be dumped on landfill sites and to be burned in incinerators.
Thus, in the process according to the invention, uncleaned plastics up to a certain degree of contamination and non-plastics materials up to a certain proportion of the total volume can be processed, added and incorporated into the resulting plastics mixtures or mixtures of plastics and non-plastics materials, this mixture together with the additional component of natural biological or synthetic origin forming a compound which is homogeneous or restrictedly,
Cain Edward J.
Finacor Anstalt
Manelli Denison & Selter PLLC
Melcher Jeffrey S.
Wyrozebski-Lee Katarzyna
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