Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Process of treating scrap or waste product containing solid...
Patent
1994-03-24
1995-11-07
Michl, Paul R.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Process of treating scrap or waste product containing solid...
521 40, 521 425, 521 435, 521 44, 521 46, 521 465, 521 485, C08J 1104, C08J 1106, B29B 1702
Patent
active
054648777
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention concerns a method for recovering synthetic waste material contaminated with other materials, by means of a chemical treatment consisting of impregnating the materials with a substance which attacks the contaminant material but is substantially neutral toward the synthetic material, and a simultaneous mechanical treatment consisting of tumbling the loose, uncrushed waste material in a hermetically sealed drum.
The synthetic waste material is usually contaminated with other materials such as one or more dyes, printing ink, metal coatings, paper or other types of tags, glue, etc. "Clean" recycling requires that the synthetic base material be free of contaminants before re-use.
Current attempts to recover such material consist of a chemical treatment during which the waste is submerged in an aggressive solution for a variable length of time in order to neutralize the contaminant material. During such treatment the solution impregnates synthetic material, which is thus partially degraded and often cannot be used again.
As the price of base materials increases, recycling synthetic materials becomes more and more important. The polycarbonate used in the manufacture of optical character reading disks is one of the more desirable materials to recycle.
Various attempts have been made to recycle polycarbonate and other synthetic materials. One such example is described in German Patent Application No. DE A 85 11 711, which describes a method of recovering synthetic waste from optical character reading disks wherein the previously crushed waste is submerged in a chemical bath consisting of several substances with solvent properties.
U.S. Pat. No. 4,802,048 describes a method for treating pieces of synthetic material coated with at least one layer of a macromolecular organic polymer, wherein the particles are first finely ground and then tumbled in a caustic soda solution. The mixture consists of 25% solid material and 75% alkaline solution.
A major drawback with all these known methods is that the previously ground or microminiaturized material for recycling is immersed in an aggressive solution, which, while successfully removing the unwanted material, also impregnates the material to be recycled.
SUMMARY OF THE INVENTION
The present invention proposes overcoming this disadvantage by providing a method which effectively treats the waste synthetic material while preventing the degradation which occurs when aggressive substances are used for treatment.
To achieve this the method of the invention is characterized by the fact that the quantity of chemical solution comprises from 2 to 5% of the weight of the quantity of waste treated.
When the waste material is an optical character reading disk With a polycarbonate base, said chemical solution preferably is composed of 20% caustic soda at 38.degree. C. and water, with the treatment lasting from 3 to 5 hours.
In a preferred embodiment of the method, at least one rinsing procedure is performed using a volume of liquid which comprises from 25% to 100% of the volume of treated waste, followed by drying the waste with hot air.
Advantageously, the rinse liquid is then filtered using a plate filter.
In one advantageous embodiment of the method, the chemical and mechanical treatments take place in a first rotary drum, rinsing and drying in a second rotary drum, and the waste is crushed after rinsing and drying. The invention will be better understood with reference to the description of one embodiment of the method and one advantageous embodiment of the device used in said method.
BRIEF DESCRIPTION OF THE DRAWINGS
A device is shown in FIG. 1 as a diagrammatic schematic and will be described in greater detail below.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The method comprises a combination of chemically treating the contaminant materials which adhere to the synthetic material for recycling with a mechanical recovery process, tumbling the product in a rotary drum. Since only a small quantity of aggressive chemical solution
REFERENCES:
patent: 4368274 (1983-01-01), Scott
patent: 4602046 (1986-07-01), Buser et al.
patent: 4799954 (1989-01-01), Hochberg
patent: 5214072 (1993-05-01), Fennhoff et al.
patent: 5248041 (1993-09-01), Deiringer et al.
Chemical Abstracts, vol. 90, No.: 6, 1979, Columbus, Ohio, U.S.; abstract No.: 39898g, Sadayoshi & Al. `recovery of base films from magnetic recording materials` see abstract.
Asinovsky Olga
Helverep S.A.
Michl Paul R.
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