Use of polypropylene oxide or ethylene oxide-propylene oxide copolymers in combination with starch ether derivatives as additive in dry mortar compositions

1. A dry mortar composition comprising:

a) 5 to 50% by weight, based on the total weight of the dry mortar composition, of a mineral binder;

b) 30 to 90% by weight, based on the total weight of the dry mortar composition, of filler;

c) a spray-dried water-redispersible polymer powder comprising a copolymer selected from the group consisting of (i) copolymers of vinyl acetate and from 5 to 50% by weight of ethylene, (ii) copolymers of vinyl acetate and from 0 to 50% by weight of ethylene and from 1 to 50% by weight of a vinyl ester of alpha-branched monocarboxylic acids having from 9 to 11 carbon atoms, (iii) copolymers of 30 to 75% by weight of vinyl acetate and from 1 to 30% by weight of vinyl laurate or vinyl esters of an alpha-branched carboxylic acid having from 9 to 11 carbon atoms and from 1 to 30% by weight of (meth)acrylic esters of unbranched or branched alcohols having from 1 to 15 carbon atoms and from 0 to 40% by weight of ethylene, (iv) copolymers of 50 to 95% by weight of vinyl acetate and from 5 to 50% by weight of (meth)acrylic esters of unbranched or branched alcohols having from 1 to 15 carbon atoms, and (v) copolymers of vinyl acetate and from 5 to 50% by weight of ethylene and from 1 to 60% by weight of vinyl chloride, wherein the copolymers can additionally contain auxiliary monomers and weight percents in each case add up to 100% by weight; and an adhesion-promoting additive combination, said additive composition comprising:

one or more polyalkylenoxides out of the group comprising polypropylene oxides and ethylene oxide-propylene oxide copolymers; and

one or more starch ether derivatives out of the group comprising carboxyalkyl starch ethers and their alkali salts, and hydroxyalkyl starch ethers, and

wherein the water-redispersible polymer powder comprises the adhesion promoting additive combinations.

2. The mortar composition of claim 1 , wherein the additive combination comprises one or more starch ether derivatives selected from the group comprising hydroxypropyl starch, carboxymethyl starch, and their sodium salts.

3. The mortar composition of claim 1 , comprising a dry mortar composition comprising a) one or more mineral binders, b) one or more fillers, c) one or more water-redispersible polymer powders based on polymers of ethylenically unsaturated monomers and having a glass transition temperature T g of from −25° C. to +25° C. and optionally d) further additives.

4. The mortar composition of claim 1 , wherein the mortar composition is a ceramic adhesive, an exterior thermal insulation composite system, or a repair mortar.

5. A method of making a dry mortar composition by combining:

a) 5 to 50% by weight, based on the total weight of the dry mortar composition, of a mineral binder;

b) a spray-dried water-redispersible polymer powder comprising a copolymer selected from the group consisting of (i) copolymers of vinyl acetate and from 5 to 50% by weight of ethylene, (ii) copolymers of vinyl acetate and from 0 to 50% by weight of ethylene and from 1 to 50% by weight of a vinyl ester of alpha-branched monocarboxylic acids having from 9 to 11 carbon atoms, (iii) copolymers of 30 to 75% by weight of vinyl acetate and from 1 to 30% by weight of vinyl laurate or vinyl esters of an alpha-branched carboxylic acid having from 9 to 11 carbon atoms and from 1 to 30% by weight of (meth)acrylic esters of unbranched or branched alcohols having from 1 to 15 carbon atoms and from 0 to 40% by weight of ethylene, (iv) copolymers of 50 to 95% by weight of vinyl acetate and from 5 to 50% by weight of (meth)acrylic esters of unbranched or branched alcohols having from 1 to 15 carbon atoms, and (v) copolymers of vinyl acetate and from 5 to 50% by weight of ethylene and from 1 to 60% by weight of vinyl chloride, wherein the copolymers can additionally contain auxiliary monomers and weight percents in each case add up to 100% by weight, and an adhesion-promoting additive combination, said additive composition comprising:

one or more polyalkylenoxides out of the group comprising polypropylene oxides and ethylene oxide-propylene oxide copolymers; and

one or more starch ether derivatives out of the group comprising carboxyalkyl starch ethers and their alkali salts, and hydroxyalkyl starch ethers.

6. The method of claim 5 , wherein the additive combination comprises one or more starch ether derivatives selected from the group comprising hydroxypropyl starch, carboxymethyl starch, and their sodium salts.

7. The method of claim 5 , wherein the dry mortar composition comprises 30 to 90% by weight, based on the total weight of the dry mortar composition, of one or more fillers, and the one or more water-redispersible polymer powders based on polymers of ethylenically unsaturated monomers have a glass transition temperature T g of from −25° C. to +25° C.

8. The method of claim 5 , wherein the dry mortar composition is a ceramic tile adhesive, an exterior thermal insulation composite system, or a repair mortar.