Compositions: coating or plastic – Coating or plastic compositions – Inorganic settable ingredient containing
Reexamination Certificate
2001-08-09
2003-05-27
Marcantoni, Paul (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Inorganic settable ingredient containing
C106S724000, C106S728000, C106S823000, C524S005000
Reexamination Certificate
active
06569234
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Technical Field
The present invention relates to a cement dispersant and a cement composition comprising this.
B. Background Art
In the recent concrete industry, the improvement of durability and strength of concrete structures is strongly desired, and the reduction of the amount of unit water is an important object for achieving this.
Until now, the use of various cement dispersants has been proposed in order to reduce the amount of unit water. Among the various cement dispersants, polycarboxylic acid-based cement dispersants are especially preferable because they display higher water-reducing capacity than other cement dispersants such as naphthalene-based ones. For example, JP-A-91320/1981 proposes copolymers as produced by using polyethylene glycol monoallyl ether and a (meth)acrylic acid monomer in a specific ratio. However, the capacity of this cement dispersant is still insufficient. In addition, JP-A-118058/1982, JP-A-283350/1996, and JP-A-142905/1997 propose cement dispersants comprising copolymers as produced by using polyethylene glycol monoallyl ether and a maleic acid-based monomer in a specific ratio. However, these cement dispersants are not in a level that can satisfy dispersibility particularly in a high water-reducing ratio area because of the problem that the copolymerizability is low between the polyethylene glycol monoallyl ether and the maleic acid-based monomer. On the other hand, JP-A-194808/1998 proposes cement dispersants comprising copolymers as produced by using polypropylene glycol polyethylene glycol mono(meth)allyl ether and an unsaturated carboxylic acid monomer. However, because the polypropylene glycol chain having high hydrophobicity accounts for higher ratio, the dispersants have low dispersibility, a large amount of the dispersant is necessary to obtain sufficient dispersibility. The dispersant having a level that can satisfy the dispersibility particularly in a high water-reducing ratio area has not been obtained in the existing circumstances.
Furthermore, it is costly to produce these conventional polycarboxylic acid-base cement dispersants. Therefore, there is a problem that the cost of concrete itself rises.
SUMMARY OF THE INVENTION
A. Object of the Invention
Accordingly, an object of the present invention is to provide: a cement dispersant which displays high dispersibility with a small addition amount and excellent dispersibility particularly even in a high water-reducing ratio area, and a cement composition comprising this.
B. Disclosure of the Invention
The present inventors diligently studied and, as a result, found that a specific copolymer displays high dispersibility with a small addition amount and is useful as a cement dispersant which is inexpensive and excellent in capacities. The specific copolymer is obtained by copolymerizing an unsaturated (poly)alkylene glycol ether monomer with an unsaturated monocarboxylic acid monomer including a (meth)acrylic acid (salt) as an essential component in a specific ratio of the entirety of the comonomers, wherein: the unsaturated (poly)alkylene glycol ether monomer includes an oxyethylene group as an oxyalkylene group in a specific amount at least; the oxyalkylene group has an average addition number of moles in a specific range; and the number of carbon atoms included in the terminal unsaturated group is in a specific range. Then, they completed the present invention on the basis of these findings.
That is to say, a first cement dispersant, according to the present invention, comprises a copolymer including: constitutional unit (I-1) derived from unsaturated (poly)alkylene glycol ether monomer (a1) as represented in general formula (1) below; and constitutional unit (II-1) derived from unsaturated monocarboxylic acid monomer (b1) as represented in general formula (2) below, as an essential component, wherein constitutional unit (II-1) includes at least one structure derived from an acrylic acid (salt),
wherein general formula (1) is:
XO(R
1
O)
n
H (1)
where: X represents an alkenyl group having 4 carbon atoms; R
1
O represents a mixture of one or more of an oxyalkylene group having 2 to 18 carbon atoms, and an oxyethylene group accounts for not less than 90 mol % of the entirety of the oxyalkylene groups; and n is an average addition number of moles and represents 1 to 300; and
wherein general formula (2) is:
where: R
2
, R
3
, and R
4
each independently represent hydrogen or a methyl group; and M represents hydrogen, a monovalent metal, a divalent metal, an ammonium group, or an organic amine group.
A second cement dispersant, according to the present invention, comprises a copolymer including: constitutional unit (I-1) derived from unsaturated (poly)alkylene glycol ether monomer (a-1) as represented in general formula (1) below; and constitutional unit (II-2) derived from unsaturated monocarboxylic acid monomer (b2) as represented in general formula (3) below, as an essential component, and is characterized in that constitutional unit (II-2) includes at least one structure derived from a methacrylic acid (salt), and that the milliequivalent of carboxyl groups in the copolymer is not more than 3.30 meq per 1 g of the copolymer when all the carboxyl groups are changed into their unneutralized form,
wherein general formula (1) is:
XO(R
1
O)
n
H (1)
where: X represents an alkenyl group having 4 carbon atoms; R
1
O represents a mixture of one or more of an oxyalkylene group having 2 to 18 carbon atoms, and an oxyethylene group accounts for not less than 90 mol % of the entirety of the oxyalkylene groups; and n is an average addition number of moles and represents 1 to 300; and
wherein general formula (3) is:
where: R
2
, R
3
, and R
4
each independently represent hydrogen or a methyl group; and M represents hydrogen, a monovalent metal, a divalent metal, an ammonium group, or an organic amine group.
A third cement dispersant, according to the present invention, comprises a copolymer including: constitutional unit (I-2) derived from unsaturated polyalkylene glycol ether monomer (a2) as represented in general formula (4) below; and constitutional unit (II-1) derived from unsaturated monocarboxylic acid monomer (b1) as represented in general formula (2) below, as an essential component, wherein constitutional unit (II-1) accounts for not more than 50 weight % of the entirety of the constitutional units, and includes at least one structure derived from an acrylic acid (salt),
wherein general formula (4) is:
YO(R
1
O)
m
H (4)
where: Y represents an alkenyl group having 2 or 3 carbon atoms; R
1
O represents a mixture of one or more of an oxyalkylene group having 2 to 18 carbon atoms, and an oxyethylene group accounts for not less than 90 mol % of the entirety of the oxyalkylene groups; and m is an average addition number of moles and represents 40 to 300; and
wherein general formula (2) is:
where: R
2
, R
3
, and R
4
each independently represent hydrogen or a methyl group; and M represents hydrogen, a monovalent metal, a divalent metal, an ammonium group, or an organic amine group.
A fourth cement dispersant, according to the present invention, comprises a copolymer including: constitutional unit (I-2) derived from unsaturated polyalkylene glycol ether monomer (a2) as represented in general formula (4) below; and constitutional unit (II-2) derived from unsaturated monocarboxylic acid monomer (b2) as represented in general formula (3) below, as an essential component, wherein constitutional unit (II-2) accounts for not more than 50 weight % of the entirety of the constitutional units, and includes at least one structure derived from a methacrylic acid (salt),
wherein general formula (4) is:
YO(R
1
O)
m
H (4)
where: Y represents an alkenyl group having 2 or 3 carbon atoms; R
1
O represents a mixture of one or more of an oxyalkylene group having 2 to 18 carbon atoms, and an oxyethylene group accounts for not less than 90 mol % of the entirety of the oxyalkylene groups; and m is an average a
Hirata Tsuyoshi
Onda Yoshiyuki
Tanaka Hiromichi
Uno Toru
Yamamoto Masaya
Haugen Law Firm PLLC
Marcantoni Paul
Nippon Shokubai Co. , Ltd.
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