Compositions: coating or plastic – Coating or plastic compositions – Inorganic settable ingredient containing
Reexamination Certificate
1999-08-30
2001-10-02
Green, Anthony (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Inorganic settable ingredient containing
C106S725000, C106S727000, C106S823000, C524S005000
Reexamination Certificate
active
06296698
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a cement admixture and to a cement composition. More particularly, it relates to a cement admixture that is added to a cement composition such as concrete, mortar, cement paste, etc. to improve the flowability, flowability retaining ability, and packing property and further impart the composition with resistance to segregation of the components and to a cement composition which is blended with such a cement admixture, which is easy to execute and operate and which gives a hardened product having an improved quality.
BACKGROUND ART
Recently, on operation spots where concrete is used, such as civil engineering spots or construction spots, vibration compaction operation is used which generates noises and hence there has been an increasing demand for concrete that requires no compaction operation in order to reduce noises and decrease work load on the spot as well. Furthermore, with increasing complexity and functionality of constructions, it is necessary to pack concrete uniformly into inside the frames where reinforcements are densely distributed. In this regard, extensive studies have been made on the development of concrete that has flowability, flowability retaining ability, high packing property, and resistance to segregation and needs no compaction operation.
Generally, a cement dispersant is added to concrete in order to improve the flowability, flowability retaining ability and packing property thereof. Such a cement dispersant includes various substances, e.g., melaminesulfonic acid formaldehyde salts, naphthalenesulfonic acid formaldehyde salts, polycarboxylic acid salts, etc.
However, these cement dispersants when added to concrete can impart flowability and flowability retaining ability to concrete due to their high dispersing effect but cause the phenomenon that concrete loses uniformity during its flow and the components of aggregate will separate, thereby deteriorating the feasibility of concrete. Furthermore, after hardening, the concrete has an inferior quality (see, for example, JP-A-5-238795 (the term “JP-A” as used herein means an “unexamined published Japanese patent application), and JP-A-5-298795, JP-A-6-225354 (U.S. Pat. No. 5,362,829)).
With view to inhibiting or suppressing the segregation, there has been studied addition of water-soluble polymers, for example, cellulose derivatives such as methyl cellulose ether, synthetic polymers such as polyacrylamide, natural polysaccharides such as cardlan as a segregation reducing agent to concrete (see, for example, JP-A-6-206752, JP-A-9-132444, and JP-A-9-2856). However, the water-soluble polymers as a segregation reducing agent have the problem that addition in an amount sufficient to inhibit the segregation results in an increase in viscosity of concrete and the flowability and flowability retaining ability of concrete are decreased.
As a segregation reducing agent that does not deteriorate the flowability and flowability retaining ability of concrete even in a concentration sufficient to suppress the segregation, there has been proposed in JP-A-10-53627 copolymers containing a N-vinylcarboxamide monomer. However, to impart concrete with flowability, flowability retaining ability, high packing property and resistance to segregation, it is necessary to add to concrete the above-mentioned cement dispersant and a segregation reducing agent consisting of copolymer containing a N-vinylcarboxamide monomer in combination.
As described above, in the prior art, it has been impossible to impart concrete with flowability, flowability retaining ability, high packing property, and resistance to segregation which are required for concrete by means of a single agent of copolymer in good balance.
PROBLEM WHICH THE INVENTION IS TO SOLVE
Therefore, an object of the present invention is to provide a cement admixture that can achieve two functions, i.e., the function of a dispersant which imparts a cement composition with improved flowability, flowability retaining ability, and packing property and the segregation inhibiting or suppressing function which imparts a cement composition with resistance to segregation of the components thereof, in the form of a single agent of copolymer.
Another object of the present invention is to provide a cement composition containing the cement admixture and having flowability, flowability retaining ability, high packing property, and resistance to segregation in good balance.
The present inventors have made extensive research with view to achieve the above-described object, and as a result the present invention has been completed.
That is, the present invention relates to the following cement admixture and to a cement composition.
[1] A cement admixture comprising a copolymer obtainable by polymerizing a monomer mixture consisting of:
(A) 2 to 85% by weight of a monomer represented by general formula (1)
(wherein, R
1
and R
2
, which is the same or different, each represent a hydrogen atom or a methyl group),
(B) 90 to 10% by weight of one or more monomers represented by general formula (2)
(wherein R
3
represents a hydrogen atom or a methyl group, X represents —C(═O)— or —CH
2
—, Y represents an alkylene group having 2 to 4 carbon atoms, R
4
represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and n is an integer of from 2 to 100), and
(C) 5 to 50% by weight of an anionic vinyl monomer,
wherein the sum of the monomers (A), (B) and (C) is 100% by weight.
[2] A cement admixture comprising a copolymer obtainable by polymerizing a monomer mixture consisting of:
(A) 2 to 85% by weight of a monomer represented by general formula (1)
(wherein, R
1
and R
2
, which is the same or different, each represent a hydrogen atom or a methyl group),
(B) 90 to 10% by weight of one or more monomers represented by general formula (2)
wherein R
3
represents a hydrogen atom or a methyl group, X represents —C(═O)— or —CH
2
—, Y represents an alkylene group having 2 to 4 carbon atoms, R
4
represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and n is an integer of from 2 to 100),
(C) 5 to 50% by weight of an anionic vinyl monomer, and
(D) 0 to 40% by weight of a vinyl monomer other than the monomers (A), (B) and (c),
wherein the sum of the monomers (A), (B), (C) and (D) is 100% by weight.
[3] The cement admixture as described in [1] or [2], wherein the monomer (A) represented by the general formula (1) is N-vinylacetamide.
[4] The cement admixture as described in [1] or [2], wherein the monomer (B) represented by the general formula (2) is one in which n is an integer of from 4 to 50.
[5] The cement admixture as described in [1] or [2], wherein the monomer (B) represented by the general formula (2) is one in which n is an integer of from 4 to 25, X is —C(═O)—, Y is —CH
2
—CH
2
—O—, and R
4
is a methyl group.
[6] The cement admixture as described in [1] or [2], wherein the anionic vinyl monomer (C) is one or more compounds selected from the group consisting of (meth)acrylic acid, maleic acid, fumaric acid, itaconic acid, (meth)allylsulfonic acid, and salts thereof.
[7] The cement admixture as described in [6], wherein the anionic vinyl monomer (C) is (meth)acrylic acid or maleic acid.
[8] The cement admixture as described in [1] or [2], wherein the vinyl monomer (D) is one or more compounds selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, 2-hydroxylethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and (meth)acrylonitrile.
[9] A cement composition containing a cement admixture imparted with resistance to segregation as claimed in any one of the above items [1] to [8].
[10] The cement composition as described in [9], wherein the cement admixture imparted with resistance to segregation is contained in a solids content of 0.1 to 2.0% by w
Hayashi Masahiro
Hiromoto Kazuhiko
Naramoto Satoru
Green Anthony
Showa Denko K.K.
Sughrue Mion Zinn Macpeak & Seas, PLLC
LandOfFree
Cement admixture and cement composition does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Cement admixture and cement composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cement admixture and cement composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2560787