Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1998-10-06
2000-06-27
Nutter, Nathan M.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
525183, C08K 517
Patent
active
060808063
DESCRIPTION:
BRIEF SUMMARY
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of international application PCT/FR97/00030 filed Jan. 8, 1997, and French application FR96/00188 filed Jan. 10, 1996.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to water-redispersible powders of film-forming polymers prepared from monomers containing ethylenic unsaturation.
2. Description of Related Art
Redispersible powders which are obtained by spray-drying of dispersions of acrylic film-forming polymers, especially of dispersions of vinyl ester polymers, are already known.
Film-forming polymers prepared from monomers containing ethylenic unsaturation are often employed as adjuvants in hydraulic inorganic binder compositions in order to improve their application and the properties after hardening, such as adhesion to various substrates, leakproofing, flexibility and mechanical properties.
When compared with aqueous dispersions, redispersbile powders offer the advantage of being capable of being premixed with cement in the form of ready-to-use pulverulent compositions that can be used, for example, for the manufacture of mortars and concretes intended to be attached to construction materials, for the manufacture of adhesive mortars or for the production of protective and decorative coatings inside or outside buildings.
It is customary to add relatively large quantities of inert substances and of protective colloids to powders, in order to succeed in obtaining powders that do not agglomerate during storage under the effect of pressure and temperature and that are conveniently redispersible in water.
To obtain readily redispersible polymer powders, it has been proposed to add to the dispersions, before the spraying, melamine-formaldehyde-sulphonate (U.S. Pat. No. 3,784,648) or naphthalene-formaldehyde-sulphonate (DE-A-3,143,070) condensation products and/or vinylpyrrolidone-vinyl acetate copolymers (EP-78,449).
French patent FR-A 2,245,723 is directed towards a stable and water-dispersible, freeze-dried preparation containing a powder of a polymer latex and a water-soluble dispersing agent which is a saccharide.
BRIEF SUMMARY OF THE INVENTION
The aim of the present invention is to propose a novel pulverulent composition which is completely or almost completely redispersible in water and which is based on a film-forming polymer prepared from monomers containing ethylenic unsaturation.
Another aim of the present invention is to propose a redispersible powder of the above type, which is stable on storage without agglomeration.
Another aim of the present invention is to propose a process for the preparation of the powders of the above type from a film-forming polymer latex.
Another aim of the present invention is to propose a redispersible powder of the above type which, in the form of powder or after possible redispersion in water in the form of a pseudolatex, can be used in any of the fields of application of latices for producing coatings (especially paints and paper-coating compositions) or adhesive compositions (especially pressure-sensitive adhesives and tiling adhesives).
Another aim of the present invention is to propose a redispersible powder of the above type (or the pseudolatex resulting therefrom) more particularly with a view to its use as additives to hydraulic binders of the mortar or concrete type and providing these binders with improved adhesion after immersion in a wet medium.
These and other aims are achieved by the present invention which relates, in fact, to a water-redispersible pulverulent composition containing: prepared from at least one monomer containing ethylenic unsaturation and at least one monomer chosen from monomers with carboxylic functionality and acrylamide or methacrylamide, one amino acid or one of its salts.
The invention also relates to the process for preparing this pulverulent composition which consists insoluble film-forming polymer prepared by emulsion polymerization and containing an appropriate amount of additives b) size.
The invention also
Bett William
Colombet Jean-Francois
Nutter Nathan M.
Rhodia Chimie
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