Sughrue, Mion, Zinn, Macpeak & Seas
Modified polyvinyl alcohol
 A modified polyvinyl alcohol is disclosed, which comprises the following structural units (I) and (II) and has a weight average molecular weight of from 3,000 to 400,000: ##STR1## wherein R.sup.1 represents H or CH.sub.3 ; and M.sup.1 represents H, an alkali metal, ammonium, alkylammonium, or alkanolammonium. The modified polyvinyl alcohol may be sulfonated. The modified polyvinyl alcohol is used as a dispersant such as a drilling fluid additive. 
Dai-Ichi Kogyo Seiyaku Co., Ltd.
C C C
C08F C09K C08F
inventional inventional inventional
Yoshihiro Akira Hiroshi Yoshiyuki Akira
Kawamori Kitada Nishiguchi Mori Yada