Cleaning system utilizing an organic and a pressurized fluid solvent

Abstract

A cleaning system that utilizes an organic cleaning solvent and pressurized fluid solvent is disclosed. The system has no conventional evaporative hot air drying cycle. Instead, the system utilizes the solubility of the organic solvent in pressurized fluid solvent as well as the physical properties of pressurized fluid solvent. After an organic solvent cleaning cycle, the solvent is extracted from the textiles at high speed in a rotating drum in the same way conventional solvents are extracted from textiles in conventional evaporative hot air dry cleaning machines. Instead of proceeding to a conventional drying cycle, the extracted textiles are then immersed in pressurized fluid solvent to extract the residual organic solvent from the textiles. This is possible because the organic solvent is soluble in pressurized fluid solvent. After the textiles are immersed in pressurized fluid solvent, pressurized fluid solvent is pumped from the drum. Finally, the drum is de-pressurized to atmospheric pressure to evaporate any remaining pressurized fluid solvent, yielding clean, solvent free textiles. The organic solvent is preferably dipropylene glycol n-butyl ether, tripropylene glycol n-butyl ether or tripropylene glycol methyl ether, a mixture thereof, or a similar solvent and the pressurized fluid solvent is preferably densified carbon dioxide.

Description

BACKGROUND [0001] 1. Field of the Invention [0002] The present invention relates generally to cleaning systems, and more specifically to substrate cleaning systems, such as textile cleaning systems, utilizing an organic cleaning solvent and a pressurized fluid solvent. [0003] 2. Related Art [0004] A variety of methods and systems are known for cleaning substrates such as textiles, as well as other flexible, precision, delicate, or porous structures that are sensitive to soluble and insoluble contaminants. These known methods and systems typically use water, perchloroethylene, petroleum, and other solvents that are liquid at or substantially near atmospheric pressure and room temperature for cleaning the substrate. [0005] Such conventional methods and systems generally have been considered satisfactory for their intended purpose. Recently, however, the desirability of employing these conventional methods and systems has been questioned due to environmental, hygienic, occupational haz...

AI Technical Summary

Benefits of technology

[0021] Thus, the cleaning system described herein utilizes solvents that are less regulated and less combustible, and that efficiently remove different soil types typically deposited on textiles through normal use. The cleaning system reduces solvent consumption and waste generation as compared to conventional dry cleaning systems. Machine and operating costs are reduced as compared to currently used pressurized fluid solvent systems, and conventional additives may be used in the cleaning system.

[0022] Furthermore, one of the main sources of solvent loss from conventional dry cleaning systems, which occurs in the evaporative hot air drying step, is eliminated altogether. Because the conventional evaporative hot air drying process is eliminated, there are no heat set stains on the substrates, risk of fire and / or explosion is reduced, the total cycle time is reduced, and residual solvent in the substrates is substantially reduced or eliminated. Substrates are also subject to less wear, less static electricity build-up and less shrinkage because there is no need to tumble the substrates in a stream of hot air to dry them.

Problems solved by technology

Recently, however, the desirability of employing these conventional methods and systems has been questioned due to environmental, hygienic, occupational hazard, and waste disposal concerns, among other things.

Furthermore, there are significant regulatory burdens placed on solvents such as perchloroethylene by agencies such as the EPA, OSHA and DOT.

Such regulation results in increased costs to the user, which, in turn, are passed to the ultimate consumer.

Certain other solvents used in dry cleaning, such as hydrocarbon solvents, are extremely flammable, resulting in greater occupational hazards to the user and increased costs to control their use.

The heat used in drying may permanently set some stains in the textiles.

Furthermore, the drying cycle adds significant time to the overall processing time.

This often results in the development of undesirable static electricity and shrinkage in the garments.

Also, the textiles are subject to greater wear due to the need to tumble the textiles in hot air for a relatively long time.

Conventional drying methods are inefficient and often leave excess residual solvent in the textiles, particularly in heavy textiles, components constructed of multiple fabric layers, and structural components of garments such as shoulder pads.

This may result in unpleasant odors and, in extreme cases, may cause irritation to the skin of the wearer.

In addition to being time consuming and of limited efficiency, conventional drying results in significant loss of cleaning solvent in the form of fugitive solvent vapor.

Finally, conventional hot air drying is an energy intensive process that results in relatively high utility costs and accelerated equipment wear.

Solvent evaporation especially during the drying cycle is one of the main sources of solvent loss in conventional systems.

While the combination of ultrasonic cavitation and liquid carbon dioxide may be well suited to processing complex hardware and substrates containing extremely hazardous contaminants, this process is too costly for the regular cleaning of textile substrates.

Furthermore, the use of ultrasonic cavitation is less effective for removing contaminants from textiles than it is for removing contaminants from hard surfaces.

The use of such co-solvents results in high solvent losses, and high fire risks.

Furthermore, many of the co-solvents are not compatible with common dyes and fibers used in textile manufacture.

Also, the use of supercritical carbon dioxide necessitates the use of more expensive equipment.

Use of these solvents would introduce a high risk of fire, high levels of solvent loss and potential damage to a wide range of textiles.

As a result, it has many of the same disadvantages as conventional dry cleaning processes described above.

Several of the pressurized fluid solvent cleaning methods described in the above patents may lead to recontamination of the substrate and degradation of cleaning efficiency because the contaminated solvent is not continuously purified or removed from the system.

Furthermore, pressurized fluid solvent alone is not as effective at removing some types of soil as are conventional cleaning solvents.

Consequently, pressurized fluid solvent cleaning methods require individual treatment of stains and heavily soiled areas of textiles, which is a labor-intensive process.

Furthermore, systems that utilize pressurized fluid solvents for cleaning are more expensive and complex to manufacture and maintain than conventional cleaning systems.

Finally, few if any conventional surfactants can be used effectively in pressurized fluid solvents.

The surfactants and additives that can be used in pressurized fluid solvent cleaning systems are much more expensive than those used in conventional cleaning systems.

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