Barium sulphate method for producing the same and the use thereof

Abstract

Barium sulfate particles having an average particle diameter d 50 of from 0.1 to 10 μm which are produced by precipitation can be dispersed better if they are covered with at least one organic additive.

1 . Barium sulfate having an average particle diameter d 50  of from 0.1 to 10 μm, precipitated by mixing of barium- and of sulfate-containing solution, characterised in that the barium sulfate particles are covered with at least one organic additive, the organic additive being selected from one or more of the substances or groups of substances: carboxylic acids, soaps, metallic soaps, alcohols; polyhydric alcohols, such as pentaerythritol, neopentyl glycol and trimethylolpropane; polyalcohols, such as polypropylene glycol and polyethylene glycol; organic esters, such as neopentyl glycol dibenzoate; silanes, siloxanes, silicone oils, organic sulfones corresponding to the formula RSO 2 R, organic ketones (R—(C═O)—R), organic nitrites (RCN), organic sulfoxides (R 2 —SO 2 ), organic amides (R—(C═O)—NR′R or R—(S═O)—ONR′R).  
     
     
         2 . Barium sulfate according to  claim 1 , characterised in that the content of organic additive, based on the content of barium sulfate, is 0.1 to 30 wt. %.  
     
     
         3 . Barium sulfate according to  claim 2 , characterised in that the content of organic additive, based on the content of barium sulfate, is 0.1 to 10 wt. %.  
     
     
         4 . Process for the preparation of barium sulfate having an average particle diameter d 50  of from 0.1 to 10 μm and precipitated by mixing of barium- and of sulfate-containing solution, characterised in that the separated filter cake is processed to form a paste, the paste is homogeneously mixed with organic additive and then dried, the organic additive being selected from one or more of-the substances or groups of substances: carboxylic acids, soaps, metallic soaps, alcohols; polyhydric alcohols, such as pentaerythritol, neopentyl glycol and trimethylolpropane; polyalcohols, such as polypropylene glycol and polyethylene glycol; organic esters, such as neopentyl glycol dibenzoate; silanes, siloxanes, silicone oils, organic sulfones corresponding to the formula RSO 2 R, organic ketones (R—(C═O)—R), organic nitriles (RCN), organic sulfoxides (R 2 —SO 2 ), organic amides (R—(C═O)—NR′R or R—(S═O)—ONR′R).  
     
     
         5 . Process for the preparation of barium sulfate having an average particle diameter d 50  of from 0.1 to 10 μm and precipitated by mixing of barium- and of sulfate-containing solution, characterised in that the separated filter cake is suspended in water, the suspension is mixed with organic additive and then dried, the organic additive being selected from one or more of the substances or groups of substances: carboxylic acids, soaps, metallic soaps, alcohols; polyhydric alcohols, such as pentaerythritol, neopentyl glycol and trimethylolpropane; polyalcohols, such as polypropylene glycol and polyethylene glycol; organic esters, such as neopentyl glycol dibenzoate; silanes, siloxanes, silicone oils, organic sulfones corresponding to the formula RSO 2 R, organic ketones (R—(C═O)—R), organic nitriles (RCN), organic sulfoxides (R 2 —SO 2 ), organic amides (R—(C═O)—NR′R or R—(S═O)—ONR′R).  
     
     
         6 . Process for the preparation of barium sulfate having an average particle diameter d 50  of from 0.1 to 10 μm and precipitated by mixing of barium- and of sulfate-containing solution, characterised in that the separated filter cake is dried and then homogeneously mixed with organic additive, the organic additive being selected from one or more of the substances or groups of substances: carboxylic acids, soaps, metallic soaps, alcohols, polyhydric alcohols, such as pentaerythritol, neopentyl glycol and trimethylolpropane; polyalcohols, such as polypropylene glycol and polyethylene glycol; organic esters, such as neopentyl glycol dibenzoate; silanes, siloxanes, silicone oils, organic sulfones corresponding to the formula RSO 2 R, organic ketones (R—(C═O)—R), organic nitrites (RCN), organic sulfoxides (R 2 —SO 2 ), organic amides (R—(C═O)—NR′R or R—(S═O)—ONR′R).  
     
     
         7 . Process according to one of  claims 4  to  6 , characterised in that the dry barium sulfate covered with organic additive is subjected to a pulverisation, preferably by means of an impact mill or jet mill.  
     
     
         8 . Process according to one of  claims 4  to  7 , characterized in that the drying is carried out in a spray dryer or mill dryer.  
     
     
         9 . Process according to one of  claims 4  to  8 , characterised in that the barium sulfate is precipitated by mixing of BaCl 2  solution or Ba(OH) 2  solution with Na 2 SO 4  solution or H 2 SO 4 .  
     
     
         10 . Use of the barium sulfate according to one of  claims 1  to  3  in the production of thermoplastics, thermosetting plastics and elastomers, in which the barium sulfate particles are dispersed.  
     
     
         11 . Use of the barium sulfate according to one of  claims 1  to  3  for dispersion in plastics compositions for the production of fibres, coating materials, adhesives, films, film supports and the like.