Cement additive, its production process and use

A cement composition comprising cement, water and a cement additive, with the cement additive comprising:

• a copolymer (A-1) and an antifoaming agent (B) as effective components, wherein the copolymer (A-1) comprises as repeating units:
• a polyalkylene glycol ether-based unit (I') represented by the following general formula (3):
• ##STR11## (wherein R.sup.1 to R.sup.3 each independently represent hydrogen or a methyl group R.sup.5 O represents one oxnalkylene group having 2 to 4 carbon atoms or a mixture of two or more of the oxyalkylene group and may be added in a block or random manner when it is a mixture, R.sup.6 represents hydrogen, R.sup.4 represents --(CH.sub.2).sub.2 -- or --C(CH.sub.3).sub.2 --, and p is an average addition number of moles of the oxyalkylene groups and represents an integer of 1 to 300);
• and a dicarboxylic acid-based unit (II') represented by the following general formula (4):
• ##STR12## (wherein X.sup.1 represents --OM.sup.2 or --Y--(R.sup.7 O)qR.sup.8, M.sup.1 and M.sup.2 each independently represent hydrogen, a monovalent metal, divalent metal, ammonium or organic amine, Y represents --O-- or --NH--, R.sup.7 O represents one oxvalkyene group having 2 to 4 carbon atoms or a mixture of two or more of the oxyalkylene group and may be added in a block or random manner when it is a mixture, R.sup.8 represents hydrogen, an alkyl group having 1 to 22 carbon atoms, phenyl group, alkylphenyl group, aminoalkyl group or hydroxylalkyl group (each alkyl group in the alkylphenyl, aminoalkyl and hydroxyalkyl groups having 1 to 22 carbon atoms), q is an average addition number of moles of the oxyalkylene groups and represents an integer of 0 to 300, and an acid anhydride group (--CO--O--CO--) may be formed in place of the groups --COOM.sup.1 and --COX.sup.1 between carbon atoms to which the groups --COOM.sup.1 and --COX.sup.1 should be bonded respectively).

A cement composition comprising cement, water and a cement additive, with the cement additive comprising:

• a copolymer (A-2) and an antifoaming agent (B) as effective components, wherein the copolymer (A-2) comprises as repeating units:
• a polyalkylene glycol ether-based unit (I") represented by the following general formula (5):
• ##STR13## (wherein R.sup.10 O represents one oxyalkylene group having 2 to 4 carbon atoms or a mixture of two or more of the oxyalkylene group and may be added in a block or random manner when it is a mixture, R.sup.9 represents --(CH.sub.2).sub.2 -- or --C(CH.sub.3).sub.2 --, and r is an average addition number of moles of the oxyalkylene groups and represents an integer of 1 to 300);
• and dicarboxylic acid-based units (II") represented by the following general formula (6):
• ##STR14## (wherein X.sup.2 represents --OM.sup.4 or --Z--(R.sup.11 O)sR.sup.12, M.sup.3 and M.sup.4 each independently represent hydrogen, a monovalent metal, divalent metal, ammonium or organic amine, Z represents --O-- or --NH--, R.sup.11 O represents one oxyalkylene group having 2 to 4 carbon atoms or a mixture of two or more of the oxyalkylene group and may be added in a block or random manner when it is a mixture, R.sup.12 represents hydrogen, an alkyl group having 1 to 22 carbon atoms, phenyl group, alkylphenyl group, aminoalkyl group or hydroxylalkyl group (each alkyl group in the alkylphenyl, aminoalkyl and hydroxyalkyl groups having 1 to 22 carbon atoms), s is an average addition number of moles of the oxyalkylene groups and represents an integer of 0 to 300, and an acid anhydride group (--CO--O--CO--) may be formed in place of the groups --COOM.sup.3 and --COX.sup.2 between carbon atoms to which the groups --COOM.sup.3 and --COX.sup.2 should be bonded respectively).