Cleaning and liquid contact with solids – Processes – Using sequentially applied treating agents
Reexamination Certificate
2000-05-30
2001-10-23
Carrillo, Sharidan (Department: 1746)
Cleaning and liquid contact with solids
Processes
Using sequentially applied treating agents
C134S016000, C134S022190, C134S030000, C134S034000, C134S035000, C134S036000, C134S037000, C134S042000, C521S040000, C521S040500, C521S041000, C521S044500, C521S046000, C521S046500, C521S047000, C521S047500, C521S048000, C521S049000, C528S480000, C241S020000, C241S024100, C241S024110, C241S024180, C241S024280
Reexamination Certificate
active
06306222
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a process for cleaning plastic materials, in which foreign materials adhered on the plastic materials are cleaned to recycle the plastic materials. More specifically, the present invention relates to a process for cleaning plastic materials, in which the plastic articles such as plastic containers for containing lubricants are cleaned to recycle the waste plastics.
BACKGROUND OF THE INVENTION
As the demand for plastic materials has increased, efforts have been made to recycle the plastics. Particularly, waste plastics are buried into the ground, or incinerated, but these methods cause soil contamination and air pollution. Accordingly, recently, researches to recycle them have been carried out to such a degree that some methods have attained to a practical stage.
Plastics are very much diversified in their kinds, and different recycling methods have to be employed for different kinds. Among the plastic articles, the plastic containers which contain lubricants are very difficult to recycle. These kinds of plastic containers are contaminated with a high viscosity lubricant component and, therefore, it is difficult to remove the contamination materials. If the temperature is raised to regenerate them, then foul toxic odors are typically generated. Accordingly, so far, a limited amount of waste lubricant containers has been regenerated into low quality products, while the rest of them has been buried or incinerated.
Generally, lubricant contains petroleum substance and additives. The additives contain phenols, zinc compounds, sulphur and its compounds, and calcium/magnesium compounds. All these substances are the causes of contaminations. Lubricants are usually packed in the amount of 2 L, 4 L, and 6 L. The lubricant containers have been mostly buried or incinerated as described above. The lubricant containers are made of polypropylene (PP), or a high density polyethylene (HDPE).
SUMMARY OF THE INVENTION
The present inventor developed a process for easily removing high viscosity contamination materials such as lubricants, so that waste plastics such as lubricant containers can be recycled. The process of the present invention is capable of removing not only lubricant but also other general high viscosity contamination materials.
Therefore, it is an object of the present invention to provide a process for cleaning plastics to recycle them, in which a solvent suitable for removing high viscosity contamination materials such as lubricant is developed to clean the plastics.
It is another object of the present invention to provide a process for cleaning plastics to recycle them, in which not only the surface contamination materials but also the internally intruded contamination materials can be cleaned.
It is still another object of the present invention to provide a process for cleaning plastics to recycle them, in which after a use at a first cleaning step, the solvent is regenerated to reuse it, and the solvent of a second cleaning step recycled to the first cleaning step, thereby minimizing the discharge amount of the contaminating materials.
It is still another object of the present invention to provide a process for cleaning plastics to recycle them, in which after cleaning the waste plastics twice, the cleaned plastics are dried by circulating a heated nitrogen gas, and in this procedure, the used nitrogen is recirculated to save the expense.
It is still another object of the present invention to provide a process for cleaning plastics to recycle them, in which the foreign materials adhered on the plastics in the form of a film are removed by using a cyclone, thereby completely removing the contamination materials.
The above objects and other objects can be achieved by the present invention as described below.
In order to accomplish the above objects, the process for cleaning plastics to recycle them according to the present invention includes the steps of: (1) carrying out a first cleaning on roughly crushed plastics of a size of 2-3 cm by using a solvent within a tumbler; (2) discharging the solvent out of the tumbler after the first cleaning; (3) carrying out a second cleaning on the plastics by using a solvent within the tumbler after the first cleaning; (4) discharging the solvent out of the tumbler after the second cleaning; (5) drying the plastics after the second cleaning by injecting a heated nitrogen gas into the tumbler; and (6) discharging the nitrogen gas out of the tumbler under a reduced pressure, whereby contamination materials adhered on surfaces and internally intruded are cleaned.
In the present invention, the solvent which is discharged after the first cleaning is called “black solvent”, and the solvent which is discharged after the second cleaning is called “yellow solvent”. The yellow solvent is recycled to the first cleaning stage. The black solvent which has been discharged at the first cleaning undergoes a regenerating process to be regenerated into a clean solvent. This clean solvent is recycled to the second cleaning stage.
When the second cleaning for the plastics is completed, a heated nitrogen gas is circulated into the tumbler to dry the cleaned plastics. Under this condition, the nitrogen gas is circulated again and again, and if a shortage of the nitrogen occurs, then the shortage is compensated by injecting nitrogen from the outside. If the drying step is completed, the internal gas is discharged under a reduced pressure. Under this condition, the contamination materials adhered on the surface of the plastics and internally intruded contamination materials are discharged in a gaseous form. On the surface of the plastics, there are attached foreign materials such as label films, and these kinds of foreign materials are removed by using a cyclone, thereby improving the purity of the cleaned plastics.
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Hong Sung-In
Kim Ik-Soo
Kim In-Bok
Noh Joong-Seok
Carrillo Sharidan
LG-Caltex Oil Corporation
Woodcock Washburn Kurtz Mackiewicz & Norris LLP
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