Hoechst Aktiengesellschaft

Hermann Schindler

Wolfgang Zimmermann

Gerd Reinhardt

Gerhard Pfahler

Matthias Kroggel

Gunther Pospich

Werner Antwerpen

Ulrich M Hutten

Matthas Gutweiler

Preparation of polyvinyl acetals which can form emulsifier- and surfactant-free aqueous dispersions and redispersible dry powders and contain copolymeric polyvinyl acetals with, in amounts sufficient to form a dispersion, comonomer units carrying sulfo salt groups which are derived from copolymeric polyvinyl alcohol (PVALs) which contained comonomer units carrying sulfonate groups in the salt form. The preparation is carried out by acetalization of the starting polyvinyl alcohols to be used with aldehydes or aldehyde acetals under acid-catalyzed acetalization conditions in an aqueous medium, emulsifier-free stable aqueous polyvinyl acetal dispersions being obtained, from which dry redispersible polyvinyl acetal powders can be obtained by spray drying or freeze drying. The polyvinyl acetals according to the invention can be plasticized by mixing in plasticizers both in their aqueous dispersion form and in the dry powder form. The polyvinyl acetals according to the invention can be employed, both in the aqueous dispersion form and in the dry powder form, in numerous fields of use where polyvinyl acetals of the type known to date are already usually used. Moreover, because of the advantageous spectrum of properties of polyvinyl acetals according to the invention, numerous new fields of use are accessible.

Polyvinyl acetals which can form emulsifier-free aqueous dispersions and

Use of copolymers based on vinyl monomers and carboxylic acid amides as a detergent additive The present invention relates to the use of copolymers comprising 75-95% by weight of the total amount of the monomer of at least one vinyl monomer which is free from carboxyl and amide groups, 5-20% by weight of at least one carboxylic acid amide of the formula (I) ##STR1## in which R is a hydrogen atom or a methylol radical, R.sup.1 is a hydrogen atom or a C.sub.1 -C.sub.3 -alkyl radical and R.sup.2 is a hydrogen atom or a methyl radical and if appropriate together with not more than 5% by weight of a copolymerizable unsaturated carboxylic acid, as a detergent additive for preventing the reabsorption of detached dyestuffs and dyestuff degradation products.

Use of copolymers based on vinyl monomers and carboxylic acid amides as

Polyvinyl butyrals (PVBs) with improved thermal stability and improved light resistance contain as stabilizers polynuclear phenols which phenolic radicals have a quaternary carbon atom in the para-position to the phenolic hydroxyl group and if desired in combination with synergistically acting, nitrogen-containing, sulfur-containing or phosphorus-containing co-stabilizers of the types a) to d). The use of the resulting films of low yellowness as interlayer films having substantially reduced yellowing for the production of laminated glasses and glass composites of silicate glass sheets is described.

Polyvinyl butyrals having improved thermal stability and light resistance

The acetalization of polyvinyl alcohol in an acidic aqueous medium in the presence of a wetting agent yields an open-cell, solid foam when the reaction medium contains gas bubbles which are preferably produced by stirring air into the reaction mixture. By carrying out the acetalization in the presence of a nucleic acid a porous shaped article is obtained in which the cells are uniformly distributed. The dried shaped article absorbs a multiple of its weight of water. It can be used for household and industrial purposes.

Open-cell shaped article made of acetalized polyvinyl alcohol and

In order to protect the environment from pollution, it is desirable to keep the polyvinyl alcohol content in waste waters as low as possible. Polyvinyl alcohol may be removed from waste waters by means of microorganisms on the the one hand, and on the other according to chemical/mechanical methods by salting-out and precipitation and subsequent separation of the solids. Advantageous is the precipitation in the form of a polyvinyl alcohol/boric acid/didiol complex, especially by means of alkaline earth metal hydroxides in an alkaline medium. Calcium hydroxide is a particularly suitable alkaline earth metal hydroxide.

Process for the separation of polyvinyl alcohol from aqueous solutions

Polyvinyl alcohol containing films and coatings having a reduced water solubility are prepared from polyvinyl alcohol having an ester number of at most 200 mg of KOH/g. This polyvinyl alcohol being readily soluble in water is submitted in aqueous phase to an after saponification with alkali metal or alkaline earth metal hydroxide rendering it insoluble at elevated temperature. The alkali or alkaline earth metal ions then are precipitated in the form of compounds difficultly soluble in water by additions of substances containing corresponding anions. The precipitate remains as inert filler in the suspension of polyvinyl alcohol thus prepared. The suspension is applied in form of films or coatings and dried.

Process for the manufacture of films and coatings containing polyvinyl

The water resistance of compositions containing polyvinyl alcohol as binder is considerably increased by incorporating therein boric acid and a buffer or a compound which on heating irreversibly reacts to render the mixture alkaline. Sodium trichloro acetate is especially suitable.

Product and process for preparing polyvinyl alcohol deposits of reduced

Starch products which were hitherto used as pore-forming substances in the manufacture of polyvinyl alcohol acetal sponges are replaced by polyethylene glycol or polyacrylamide. This results in a more uniform distribution of pore size, lower shrinkage of the sponge material during the acetalization, and easier washing of the sponge after the acetalization.

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Hofheim, Germany

Hermann Schindler