Patent ID: 6166112
Filing Date: 2000-12-26
Classification: C04B,C08F,C08G,C08L

Abstract:
A cement admixture, comprising a polycarboxylic acid as an effective component, wherein the polycarboxylic acid is obtained by a process including the steps of:charging ""a"" parts by weight of a polyalkylene glycol (A) of the general formula (1) below and ""b"" parts by weight of a (meth)acrylic acid monomer (1) of the general formula (2) below into a reactor in the range of the equation (1) below;carrying out an esterification reaction of the resultant mixture in the reactor, thus obtaining a polyalkylene glycol (meth)acrylate (C) of the general formula (3) below, wherein the esterification reaction converts not less than 90% of the polyalkylene glycol (A) of the general formula (1) below to obtain the polyalkylene glycol (meth)acrylate (C) of the general formula (3) below; andcopolymerizing the resultant polyalkylene glycol (meth)acrylate (C) and the (meth)acrylic acid monomer (B), thus obtaining the polycarboxylic acid;wherein the general formula (1) is:HO(R.sup.1 O).sub.n R.sup.2 ( 1)wherein the general formula (2) is: ##STR6## wherein the equation (1) is{(a/n.sup.1/2)/b}.times.100.ltoreq.200 (1)wherein the general formula (3) is: ##STR7## wherein R.sup.1 O is one kind of oxyalkylene group or a mixture of two or more kinds thereof, wherein the two or more kinds of oxyalkylene groups may be added either in block form or at random; R.sup.2 is an alkyl group with 1 to 22 carbon atoms; n is an average molar number of the added oxyalkylene groups and is a number of 1 to 300; and R.sup.3 is a hydrogen atom or a methyl group.