Cleaning and liquid contact with solids – Processes – Using sequentially applied treating agents
Reexamination Certificate
2000-04-17
2001-10-23
Carrillo, Sharidan (Department: 1746)
Cleaning and liquid contact with solids
Processes
Using sequentially applied treating agents
C134S002000, C134S003000, C134S022170, C134S022190, C134S025400, C134S026000, C134S034000, C134S036000, C134S040000, C134S041000, C134S042000, C134S902000, C510S175000, C510S245000, C510S254000, C510S365000, C510S434000
Reexamination Certificate
active
06306223
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a degreasing process which uses a water-rinsable, surfactant-free composition.
2. Description of the Related Art Including Information Disclosed Under 37 C.F.R. 1.97 and 1.98.
Due to the non-polar or virtually non-polar nature of the fatty substances to be removed, the degreasing solvents for the conventional compositions used are conventionally chosen from products of similar polarity, such as, for example, aliphatic or aromatic hydrocarbon-based solvents. The main drawback associated with such solvents, which is in fact one of the consequences of their choice as constituents in degreasing formulations, relates to their virtual immiscibility in water, which complicates and/or lengthens the step for rinsing the objects treated. In order to facilitate this step, it is common practice to employ surfactants which become associated with the hydrocarbon-based solvent and entrain it during the rinsing step. However, they can in turn pose problems of contamination of the waters and quite often require the use of steps for the additional treatment of the rinsing waters.
BRIEF DESCRIPTION OF THE INVENTION
The process according to the present invention does not present these drawbacks since, with the specific combination of degreasing steps, the process according to the invention makes it possible, firstly, to recycle a large portion of these solvent mixtures.
Secondly, at the end of the treatment, the process according to the invention requires only simple rinsing of the degreased article with water, in the absence of any additive of the surfactant type in the degreasing formulation. Consequently, the contamination problems are all the more reduced.
In addition, the process according to the invention uses compounds which present few risks of explosion under the temperature conditions of the process, which is a definite advantage in terms of the safety of implementation of the operation for degreasing articles.
Thus, the process according to the invention consists in carrying out the following steps:
at least a first degreasing operation is carried out on the article to be treated, in the presence of a solvent mixture comprising at least one compound (a) chosen from C
1
-C
4
dialkyl esters of at least one C
4
-C
6
aliphatic diacid, and at least one compound (b) which is miscible in the compound (a) and which at least partially dissolves the fatty substance contaminating the article,
at least a second degreasing operation is optionally carried out, in the presence of a solvent mixture comprising at least one compound (a) and at least one compound (b) as defined above, with a compound (a)/compound (b) volume ratio of greater than or equal to 1,
a third degreasing operation is carried out in the presence of compound (a),
the article thus treated is rinsed with water.
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Carrillo Sharidan
Rhodia Chimie
Seugnet Jean-Louis
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