Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Patent
1998-04-02
1999-12-07
Gupta, Yogendra
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
510250, 510253, 510462, 510473, C11D 322, C11D 3382
Patent
active
059983493
DESCRIPTION:
BRIEF SUMMARY
This application is an application under 35 U.S.C. Section 371 of International Application Number PCT/FR96/01206, filed on Jul. 31, 1996.
The present invention relates to descaling and cleaning formulations based on cellulose microfibrils.
Detergent formulations used for descaling have quite specific characteristics. Thus, the products forming part of its composition must be capable of remaining stable and of retaining their properties at very acidic pH levels, which are mostly less than 2 and quite often less than 1. Moreover, it is very desirable for the rheology of the formulations to be of the pseudoplastic type. The reason for this is that, for optimum use, these formulations must have a low viscosity when they are subjected to high shear, as is the case during application of the product, followed by a high viscosity when the shear strains are low, so as to allow slow running down the walls to be descaled.
Current formulations are based on a mixture of surfactants representing up to 10% of the weight of the formulation. However, formulations of this type are not entirely satisfactory, in the sense that the rheological behaviour is not pseudoplastic but newtonian. Furthermore, such formulations are relatively expensive since the amount of surfactant is very large.
Standard thickeners such as polysaccharides have been tested in media whose pH is less than 1, but without great success. The reason for this is that these products are not very stable in such media and increasingly degrade the lower the pH.
The aim of the present invention is to propose a descaling formulation with a pseudoplastic rheological profile, which is stable over time.
Thus, the subject of the invention is a descaling formulation comprising cellulose microfibrils, in which at least 80%, preferably at least 85%, of the cells have primary walls and not more than 20%, preferably not more than 15%, of the cells have secondary walls, with a degree of crystallinity of not more than 50%, preferably not more than 40%.
However, other characteristics and advantages of the present invention will become more apparent on reading the description and the examples which follow.
Thus, it has been found that the microfibrils mentioned above give the formulation a rheology of pseudoplastic nature and, moreover, that these microfibrils, surprisingly, remain stable and retain their properties in very acidic media, i.e. media whose pH is between 0 and 1.
The microfibrils forming part of the composition of the formulations according to the invention thus consist of cellulose.
Cellulose represents the essential component of plant cell walls. These walls consist of primary walls (parenchymal cells) and secondary walls, in various proportions depending on the nature of the plant from which they are obtained. The primary walls mainly comprise certain pectins and proteins and little cellulose, generally about 5%, and depend on the growth of the cell. The fibrils in the secondary walls consist of networks forming lamellae in which is found a layer S.sub.1 (thickness of 0.2 to 0.35 .mu.m) comprising very entangled and spiralled microfibrils, a layer S.sub.2 (thickness of 1.8 to 3.8 .mu.m) based essentially on cellulose in a very compact, oriented form, and whose relatively unentangled microfibrils form concentric lamellae, and, lastly, a layer S.sub.3 (thickness of 0.1 to 0.15 .mu.m) based on entangled and spiralled cellulose fibres.
The microfibrils used as additives in the formulations according to the invention have at least 80%, preferably at least 85%, of cells with primary walls and not more than 20%, preferably not more than 15%, of cells with secondary walls.
In addition, the cellulose microfibrils have an average diameter of between 20 and 40 .ANG., preferably between 30 and 40 .ANG..
As has been mentioned previously, the degree of crystallinity of the microfibrils is not more than 50%, preferably not more than 40%. More particularly, the degree of crystallinity is between 20 and 38%.
The length of these microfibrils is about 10 .mu.m and less. Microfi
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Gupta Yogendra
Ingersoll Christine
Rhodia Chimie
Seugnet Jean-Louis
Wood John Daniel
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