Non-tacky, redispersible polymer powders for quick setting concrete or mortar

摘要

Redispersible polymer powder (A) contains 3-50 wt.% water-soluble graft polymer prepd. by: (a) radical graft polymerisation of a polyalkylene oxide of formula (I) with an ethylenic unsatd. mono- or dicarboxylic acid (anhydride); and (b) reacting with a prim. or sec. amine and/or alcohol; R<1> = H, 1-18 C alkyl, -C6H4-(1-18 C)alkyl; -(CH-R<2>)mNHR<2>, -(CH-R<2>)mOH, -(CH-R<2>)m-COOH or -CO-R<5>; R<2> = H or (m)ethyl; R<3> = H, 1-18 C alkyl, 1-5 C alkyl sulphonate Na salt, -(CH-R<2>)mNHR<2>, -(CH-R<2>)mOH, -(CH-R<2>)m-CO-, OH or -COR<5>; R<4> = H, -(CH-R<2>)m-COOH or -CO-R<5>; R<5> = 1-5 C alkyl, phenyl, -(CH-R<2>)m-COOH or -C6H4-COOH; m = 1-5; x = 2-200; and y = 0-1. Also claimed is the prepn. of (A) by adding the graft polymers and opt. additives to the polymer dispersion and then spray drying. (A) are used as additives for hydraulic binders such as cement, pref. in an amt. of 5-30 wt.% w.r.t. the binder (claimed) for the prepn. of concrete or mortar, esp. quick setting flooring or filler materials. The graft polymer prevents agglomeration of (A) during spray drying and increases the stability during storage without any detrimental effect on the viscosity or properties of the binder.