Method of fiber scouring with supercritical carbon dioxide

Details Method of fiber scouring with supercritical carbon dioxide Method of fiber scouring with supercritical carbon dioxide

1998-12-04

2001-02-06

Gupta, Yogendra (Department: 1751)

Bleaching and dyeing; fluid treatment and chemical modification

Cleaning or laundering

Scouring, degreasing or bowking

C008S138000, C008S142000

Reexamination Certificate

active

06183521

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to a method of fiber scouring. More particularly, it relates to a method for removing oil agents from fibers using supercritical carbon dioxide as an extraction media.
2. Description of the Related Arts
As known in the art, spinning oils and finishing oils are respectively applied to the surface of artificial fibers when they are subjected to spinning and false twisting. The most commonly used spinning oils are ethylene oxide/propylene oxide (EO/pO) copolymer ester, while finishing oils are commonly coning oils. The spinning and finishing oils must be scoured from the fibers before they are subjected to subsequent processing, i.e., dyeing.
Referring to
FIG. 1
, the conventional scouring for artificial fibers includes three successive steps. The artificial fibers with oils agents are scoured with strong bases and scouring agents, neutralized with weak acids, and finally, rinsed by hot water. The major drawback of such method is that it necessitates a large quantity of rinsing agents including water, scouring agents, strong bases, and weak acids, thus making the practice of this method costly. Moreover, a substantial quantity of wastewater will be produced from the rising agents, whose treatment also raises the costs. Another drawback of the conventional scouring is its low efficiency. In general, it takes about 45 minutes to complete the scouring process.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a method of scouring fibers which reduces costs and improves efficiency, and does not produce wastewater.
To attain the above object, the present invention provides a method for scouring fibers by flowing carbon dioxide through the fibers under pressure and temperature conditions such that the carbon dioxide is a supercritical fluid and removes a substantial portion of the oil content from the fibers, which can be either natural fibers or artificial fibers such as polyester or nylon fibers.
The method using carbon dioxide to remove oils from fibers operates at moderate pressures between 90 and 350 bar and at temperature levels ranging from 40 to 120° C. The extraction efficiency can be modulated by varying the operating pressures and temperatures.
The present method is superior to the conventional method in several ways. The most important advantage of this method is its low cost. Referring to
FIG. 2
, this method significantly reduces the production cost by obviating the need for using large quantities of rinsing agents. Accordingly, the need for treating wastewater is also eliminated. It is also financially advantageous that the carbon dioxide can be recycled and the oil extract can be recovered. Another advantage of this method is its high efficiency. The scouring time of the present method is about ten minutes, whereas that of conventional scouring is about 45 minutes. A further advantage of this method is that the extraction efficiency can be simply controlled by regulating the operating pressures and temperatures. In addition, by using the supercritical carbon dioxide, the integration of the scouring process into the supercritical carbon dioxide dyeing process is made possible.


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