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JP-7855334-B2 - Admixture for hydraulic compositions

JP7855334B2JP 7855334 B2JP7855334 B2JP 7855334B2JP-7855334-B2

Inventors

  • 岩本 亮司
  • 谷所 美明

Assignees

  • 花王株式会社

Dates

Publication Date
20260508
Application Date
20211108

Claims (8)

  1. An admixture for hydraulic compositions comprising: (A) a copolymer having constituent units (a1) derived from an olefin with 6 to 14 carbon atoms and constituent units (a2) derived from one or more compounds selected from maleic acid and fumaric acid, with a weight-average molecular weight of 10,000 to 100,000 [hereinafter referred to as component (A)] in a quantity of 0.5% to 15% by mass ; (B) a copolymer having constituent units derived from a compound (b1) represented by the following general formula (b1) and constituent units derived from a compound (b2) represented by the following general formula (b2) [hereinafter referred to as component (B)] in a quantity of 3% to 50% by mass; and water, wherein the ratio of the content of component (A) to the total content of components (A) and (B) is 5% to 70% by mass, and the electrical conductivity is 11 mS/cm or less. [During the ceremony, R1b , R2b : May be the same or different, hydrogen atom or methyl group; R3b : hydrogen atom or -(CO) q O(AO) n X X: Alkyl group or hydrogen atom having 1 to 4 carbon atoms. AO: Group selected from ethyleneoxy group and propyleneoxy group. n: Average number of moles of AO added, between 1 and 300. p: Number between 0 and 2. q: Number of 0 or 1. [During the ceremony, R4b , R5b , R6b : may be the same or different, and are a hydrogen atom, a methyl group, or ( CH2 ) rCOOM1 , and ( CH2 ) rCOOM1 may form an anhydride with COOM or other (CH2)rCOOM1 , in which case M and M1 of those groups do not exist. M, M1 : May be the same or different, and represent a hydrogen atom, alkali metal, alkaline earth metal (1/2 atom), ammonium group, alkylammonium group, or substituted alkylammonium group. r: Represents a number between 0 and 2.
  2. The admixture for hydraulic compositions according to claim 1, comprising (B) a copolymer having a constituent unit derived from a compound in general formula (b1) where p is 1 or more and q is 0.
  3. The admixture for hydraulic compositions according to claim 1 or 2, comprising as component (B), a copolymer having a constituent unit derived from a compound in general formula (b1) where p is 2 and q is 0.
  4. (B) The admixture for hydraulic compositions according to any one of claims 1 to 3, comprising a copolymer having a constituent unit derived from a compound in general formula (b1) where p is 0 and q is 1.
  5. (B) An admixture for hydraulic compositions according to any one of claims 1 to 4, comprising two or more components.
  6. (B) The admixture for hydraulic compositions according to any one of claims 1 to 5, wherein the proportion of copolymer having a constituent unit derived from a compound in general formula (b1) where p is 1 or more and q is 0 is 60% by mass or more in component (B).
  7. An admixture for hydraulic compositions according to any one of claims 1 to 6, containing a total of 10% by mass or more and 30% by mass or less of component (A) and component (B).
  8. (A) The molar ratio of constituent unit (a1) to constituent unit (a2) constituting component (A) is 0.8 or more and 1.2 or less, as an admixture for hydraulic compositions according to any one of claims 1 to 7.

Description

This invention relates to an admixture for hydraulic compositions. Concrete admixtures are materials used to modify the properties of concrete by reacting with or combining them with cement paste. Many consist of inorganic powders and are widely used as cement substitutes or to impart special functions to concrete. Typical admixtures include blast furnace slag and artificial pozzolanes (fly ash, silica fume, etc.), intended as cement substitutes. Proper addition of these is crucial in concrete production. Generally, blast furnace slag, fly ash, silica fume, and lignite contain black fine powders. However, in recent years, the increased use of silica fumes, fly ash, and blast furnace slag, the mixing of incinerated ash into cement (utilization of industrial waste), the use of aggregates and admixtures containing lignite, and the increased fluidity of concrete aimed at improving workability and environmental friendliness have caused black spots to appear on the surface of hardened concrete or the entire surface to darken. This phenomenon is particularly noticeable in concrete using polycarboxylic acid polymers as water-reducing agents, and effective improvement measures are desired. Patent Document 1 discloses a hydraulic admixture comprising a specific olefin-maleic acid copolymer (I) and one or more copolymers (II) selected from the group consisting of specific copolymers (A), (B), and (C). Patent Document 2 discloses a concrete admixture containing an olefin-maleic acid copolymer (1) having a weight-average molecular weight of 1,000 to 20,000 and constituent units consisting of divalent hydrocarbons having 6 to 14 carbon atoms, and a polycarboxylic acid polymer (2) other than (1). Patent Document 3 discloses an agent for inhibiting the deposition of black deposits on the surface of hardened concrete containing a copolymer of a monoolefin having 6 to 10 carbon atoms and maleic acid, or a salt thereof; and a method for improving the appearance of the surface of hardened concrete by adding 0.0001 to 0.1 parts by mass of a copolymer of a monoolefin having 6 to 10 carbon atoms and maleic acid, or a salt thereof, on a solid content basis, to 100 parts by weight of cement. Japanese Patent Publication No. 2006-083001Japanese Patent Publication No. 2004-175651Japanese Patent Publication No. 2004-083303 The inventors have found that by reducing the electrical conductivity of an admixture for hydraulic compositions to 11 ms/cm or less, the storage stability of the admixture, for example, its storage stability at temperatures above 40°C, is improved. The reason for this improved storage stability is not entirely clear, but it is thought to be as follows. It is believed that when the electrical conductivity of an admixture for aqueous compositions increases (i.e., the amount of ions in the admixture increases), the interaction of ions with water makes it easier for polymers to separate. Therefore, by keeping the electrical conductivity of the admixture within a predetermined range, the interaction of ions with water is reduced, and the storage stability of the admixture, especially its storage stability at high temperatures, is improved. However, the present invention is not limited to this mechanism. The admixture for hydraulic compositions of the present invention comprises component (A), component (B), and water, and has an electrical conductivity of 11 ms/cm or less. Component (A) is a copolymer having a constituent unit (a1) derived from an olefin [hereinafter referred to as constituent unit (a1)] and a constituent unit (a2) derived from one or more compounds selected from maleic acid and fumaric acid [hereinafter referred to as constituent unit (a2)]. Examples of constituent monomers constituting component (A) include olefins and maleic acid, maleic anhydride, maleate, fumaric acid, and fumarate. Examples of the salts include monovalent metal salts such as sodium salts and potassium salts, divalent metal salts such as magnesium salts, and organic amine salts such as ammonium salts, monoethanolamine salts, diethanolamine salts, and triethanolamine salts, with sodium salts being preferred. Component (A) is preferably a copolymer having a structural unit (a1-1) and a structural unit (a2) derived from a chain-like olefin. From the viewpoint of not inhibiting the dispersion of carbons and cement, the number of carbon atoms in the olefin is 6 or more, preferably 8 or more, and 14 or less, preferably 12 or less, and more preferably 10 or less. Component (A) is preferably a copolymer having a structural unit (a) represented by the following general formula (a). Component (A) can be used by one or more types. [During the ceremony, R: A divalent hydrocarbon group with 6 to 14 carbon atoms. X: A hydrogen atom, a monovalent metal, a divalent metal, an ammonium group, or an organic ammonium group. Component (A) can be an acidic or neutralized salt, and the degree of neutralization can be arbitrarily selected. Therefore, X in