O/W wax dispersions and plaster products obtainable from them

Abstract

The invention relates to O/W wax dispersions based on water, an emulsifier and a wax phase containing predominantly aliphatic hydrocarbons and polar compounds having chain lengths of at least 18 carbon atoms, and also plaster compositions comprising the O/W wax dispersion, and the use of the O/W wax dispersion.

1 . An O/W wax dispersion comprising:
 at least 30% by wt. water,   at least 20% by wt. wax phase as the disperse phase, wherein the wax phase or all of the substances used to create the wax phase have a saponification number greater than 0.2 mgKOH/g,   at least 0.1% by wt. of an emulsifier or thickening agent as dispersing adjuvant, and   
       wherein the wax phase comprises the following, based on the wax phase:
 (a) 50 to 98% by wt. aliphatic hydrocarbons (HC) or mixtures thereof, each with a solidification point above 50° C. and below 95° C., 
 (b) 2 to below 50% by wt. from polar, long-chain compounds with at least 18 carbon atoms, containing
 at least one carboxyl group, optionally partially or fully derivated, and/or 
 an ether group and/or 
 at least one hydroxyl group (—OH) 
 
  per molecule, but no more than three of the afore-mentioned groups together, 
 
       and optionally a maximum of 20% by wt. other substances wherein
 (c) a maximum of 10% by wt. of said other substances are solid at room temperature and 
 (d) a maximum of 3% by wt. of said other substances are liquid at room temperature, 
 
       wherein the wax phase comprises carnauba wax, esterified colophonium resins and/or beeswax and the wax dispersion has a pH value greater than 11. 
     
     
         2 . (canceled) 
     
     
         3 . The wax dispersion according to any one of  claims 1  or  25 , characterised in that over 0 to 10% by wt., particularly 1 to 3% by wt., water-soluble alkaline substances, optionally at least partially bound through the saponification of acid groups, are contained or added. 
     
     
         4 . The wax dispersion according to any one of  claims 1  or  25 , characterised in that the HC's are selected from:
 petroleum paraffin (PP) with over 25 carbon atoms on average,   synthetic alphaolefins (hydrogenated or not hydrogenated) (AO) with over 30 carbon atoms on average,   Fisher-Tropsch (FT) waxes with over 25 carbon atoms on average and   mixtures thereof.   
     
     
         5 . The wax dispersion according to any one of  claims 1  or  25 , characterised in that the wax phase or the total substances used to create the wax phase has a saponification number of 0 to 40 mgKOH/g, particularly 0 to 7 mgKOH/g, before the possible (further) saponification or (further) alkali/earth alkali addition. 
     
     
         6 . The wax dispersion according to any one of  claims 1  or  25 , characterised in that the wax phase or the total substances used to create the wax phase has a saponification number of over 0.2 to 120 mgKOH/g, particularly 1 to 20 mgKOH/g, before the possible (further) saponification or (further) alkali/earth alkali addition. 
     
     
         7 . The wax dispersion according to any one of  claims 1  or  25 , characterised in that the wax phase has a colour number below 0.5 (according to ASTM D 1500). 
     
     
         8 . The wax dispersion according to any one of  claims 1  or  25 , characterised in that the polar compounds are oxidised HC's, comprising oxidised FT and/or polyethylene types and/or ethers, alone or in mixtures, particularly oxidised HC's and/or partially saponified oxidised HC's or mixtures of carnauba wax and oxidised HC's, optionally each saponified. 
     
     
         9 . The wax dispersion according to any one of  claims 1  or  25 , characterised in that the wax phase has a solidification point of over 55° C. to 95° C., preferably 62° C. to 80° C. 
     
     
         10 . The wax dispersion according to any one of  claims 1  or  25 , characterised in that the proportion of HC's being linear is greater than 50% by wt., particularly greater than 65% by wt. 
     
     
         11 . The wax dispersion according to any one of  claims 1  or  25 , characterised in that the wax phase has a pH value of 11 to 13. 
     
     
         12 . The wax dispersion according to any one of  claims 1  or  25 , characterised in that the particle/droplet diameter of the disperse phase is 0.1 to 10 μm, advantageously from 0.5 to 2 μm. 
     
     
         13 . The wax dispersion according to any one of  claims 1  or  25 , characterised in that the wax phase has a needle penetration value from 7 to 17 (according to ASTM D 1321) at 25° C. 
     
     
         14 . The wax dispersion according to any one of  claims 1  or  25 , characterised in that the wax dispersion has a Brookfield viscosity at 25° C. (ASTM D 2983) of under 2000 mPas/s. 
     
     
         15 . The wax dispersion according to any one of  claims 1  or  25 , characterised in that the polar, long-chain compounds are aliphatic. 
     
     
         16 . The wax dispersion according to any one of  claims 1  or  25 , characterised in that the wax phase contains less than 5% by wt. and particularly less than 0.5% by wt. other substances that are solid at room temperature, the O/W wax dispersion preferably contains no other solid substances at room temperature. 
     
     
         17 . The wax dispersion according to any one of  claims 1  or  25 , characterised in that the wax phase contains under 0.2% by wt. substituted phenols, such as alkyl phenols, preferably none. 
     
     
         18 . The wax dispersion according to any one of  claims 1  or  25 , characterised in that the polar compounds comprise carnauba wax, particularly 1 to 20% by wt. relative to the wax phase. 
     
     
         19 . The wax dispersion according to any one of  claims 1  or  25 , characterised in that the wax dispersion comprises polyvinyl alcohols, particularly 0.5 to 4% by wt., optionally partially hydrolised (over 70%). 
     
     
         20 . The wax dispersion according to any one of  claims 1  or  25 , characterised in that the polar compounds comprises esterified colophonium resins, beeswax and/or carnauba wax and/or mixtures of these, optionally each partially saponified. 
     
     
         21 . The wax dispersion according to any one of  claims 1  or  25 , characterised in that the wax dispersion contains less than 5% by wt., particularly less than 2% by wt., montan waxes relative to the wax phase in each case, preferably none. 
     
     
         22 . (canceled) 
     
     
         23 . A gypsum composition containing over 50% by wt., particularly 50 to 70% by wt. gypsum, relative to calcium sulphate dihydrate, optionally hydrated, and 0.1 to 5% by wt., preferably 0.5 to 2.5% by wt., of the wax dispersion of  claim 1 . 
     
     
         24 . The gypsum composition of  claim 23 , characterised in that the gypsum composition contains less than 5% by wt., particularly less than 2% by wt., montan waxes, relative to the wax phase in each case, preferably none. 
     
     
         25 . A method of obtaining a wax dispersion comprising:
 combining at least 30% by wt. water with at least 20% by wt. wax phase as the disperse phase, wherein the wax phase or all of the substances used to create the wax phase have a saponification number greater than 0.2 mgKOH/g, and   wherein the wax phase comprises the following, based on the wax phase:
 (a) 50 to 98% by wt. aliphatic hydrocarbons (HC) or mixtures thereof, each with a solidification point above 50° C. and below 95° C., 
 (b) 2 to below 50% by wt. from polar, long-chain compounds with at least 18 carbon atoms, containing 
 at least one carboxyl group, optionally partially or fully derivated, and/or 
 an ether group and/or 
 at least one hydroxyl group (—OH) 
    per molecule, but no more than three of the afore-mentioned groups together,   and at least one emulsifier to form a mixture;   homogenizing the mixture, wherein the wax phase liquefies as a result of temperature rise during homogenization; and   cooling the homogenized mixture to solidify at least a part of the mixture.