Abstract: Disclosed are the following: a cement dispersant which is excellent in initial dispersibility and further in flow retainability of cement, because of using a polymer having a proper molecular weight distribution; a process for producing this cement dispersant; and a cement composition using this cement dispersant. The cement dispersant comprises a water-soluble polymer (P) as a main component, and is characterized by displaying an area proportion (a value (A?B) given by subtracting an area ratio B of a lower molecular weight side portion from an area ratio A of a higher molecular weight side portion) in the range of 13 to 60%.

Abstract: Disclosed are the following: a cement dispersant which is excellent in initial dispersibility and further in flow retainability of cement, because of using a polymer having a proper molecular weight distribution; a process for producing this cement dispersant; and a cement composition using this cement dispersant. The cement dispersant comprises a water-soluble polymer (P) as a main component, and is characterized by displaying an area proportion (a value (A?B) given by subtracting an area ratio B of a lower molecular weight side portion from an area ratio A of a higher molecular weight side portion) in the range of 13 to 60%.

Abstract: There are provided a cement admixture which enhances water reducing property and flowability of a cement composition, and is excellent in slump retaining performance to retain the flowability with time, a polycarboxylic acid-based polymer for a cement admixture suitable therefor, a producing method thereof, and a cement composition. One cement admixture of the present invention contains copolymers (A) and (B) as an essential component, weight average molecular weights (AMw and BMw) of copolymers (A) and (B) are AMw>BMw, or peaktop molecular weights (AMp and BMp) of copolymers (A) and (B) are AMp>BMp. Another cement admixture of the present invention contains a polycarboxylic acid-based polymer having a lower molecular weight side area ratio P of 50 to 87%.

Abstract: The admixtures for a cementitious composition of the invention, which have the above-mentioned constitutions, can suitably be used in cement pastes, mortar, concrete and like cement compositions and can stabilize the amount of air entrained with the lapse of time and thus facilitate the quality control of cement compositions and, further, can improve the workability of cement compositions owing to their excellent dispersing capacities. The cement compositions of the invention which comprise such admixture for a cementitious composition are excellent in water-reducing ability and workability and can give hardened products excellent in strength and durability and, further, can stably maintain the amount of air entrained without allowing increases in the amount of air even when the time of kneading is prolonged in the production.

Abstract: It is an object of the present invention to provide a polycarboxylic acid polpolymer which improves the water reducing capacity and workability of cement compositions and the like and making them easier to handle when the fluidity and water reducing capacity are at the same levels, a method of producing the copolymer, and a cement additive and a cement composition comprising the copolymer. The present invention is further to provide a polycarboxylic acid copolymer and a cement additive which are capable of improving the strength and durability of hardening products of cement compositions, hence can advantageously be used in ultrahigh strength concrete. The present invention is polycarboxylic acid copolymers having high water reducing capacity, reducing the viscosity of cement compositions and improving the workability in applying cement.

Abstract: There is provided: a (meth)acrylic acid (salt) polymer which has high properties and is little colored; and a process which can produce this polymer with a high polymerization conversion without causing the corrosion of the reaction vessel.

Abstract: It is an object of the present invention to provide a polycarboxylic acid copolymer which improves the water reducing capacity and workability of cement compositions and the like and making them easier to handle when the fluidity and water reducing capacity are at the same levels, a method of producing the copolymer, and a cement additive and a cement composition comprising the copolymer. The present invention is further to provide a polycarboxylic acid copolymer and a cement additive which are capable of improving the strength and durability of hardening products of cement compositions, hence can advantageously be used in ultrahigh strength concrete. The present invention is still further to provide a method of producing polycarboxylic acid copolymers having high water reducing capacity, reducing the viscosity of cement compositions and improving the workability in applying cement.

Abstract: An cross-linked anion exchange resin or a salt thereof obtained by reacting a polymer (A) having amino and/or imino groups in the total number of two or more per molecule with a compound (B) having two or more functional groups capable of reacting with amino and/or imino group contained in the polymer (A). The resin or salt has a water absorption ratio of 4.0 or lower.

Abstract: It is an object of the present invention, which has been made in view of the above-mentioned state of the art, to provide a cement admixture capable of improving the water-reducing ability of cement compositions and the like and enhancing the strength and durability of hardened products produced therefrom and further capable of adjusting the viscosity of such compositions so as to facilitate the works at the sites of handling the same, as well as a method of producing such cement additive.

Abstract: A method for the production of an esterified product which can prevent the occurrence of a gel-like substance during the separation and removal of the water formed by the reaction in the esterification reaction or during the expulsion of a dehydrating solvent by distillation after the esterification reaction by causing an antigelling agent to act on the distillate and consequently permits efficient production of the esterified product of high quality, and an apparatus therefor are to be provided.

Abstract: A crosslinked anion exchange resin or a salt thereof obtained by reacting a polymer (A) having amino and/or imino groups in the total number of two or more per molecule with a compound (B) having a vinyl group capable of reacting in Michael addition reaction and a carboxylic ester group, and thus by making the amino and/or imino groups contained in the polymer (A) add to the vinyl group in the compound (B) and form a amide-bond with the carboxylic ester group in the compound (B).

Abstract: There is provided: a (meth)acrylic acid (salt) polymer which has high properties and is little colored; and a process which can produce this polymer with a high polymerization conversion without causing the corrosion of the reaction vessel.

Abstract: Disclosed are the following: a cement dispersant which is excellent in initial dispersibility and further in flow retainability of cement, because of using a polymer having a proper molecular weight distribution; a process for producing this cement dispersant; and a cement composition using this cement dispersant. The cement dispersant comprises a water-soluble polymer (P) as a main component, and is characterized by displaying an area proportion (a value (A−B) given by subtracting an area ratio B of a lower molecular weight side portion from an area ratio A of a higher molecular weight side portion) in the range of 13 to 60%.

Abstract: An cross-linked anion exchange resin or a salt thereof obtained by reacting a polymer (A) having amino and/or imino groups in the total number of two or more per molecule with a compound (B) having two or more functional groups capable of reacting with amino and/or imino group contained in the polymer (A). The resin or salt has a water absorption ratio of 4.0 or lower.

Abstract: The objective of the present invention is to provide a cement additive which causes no increase in the amount of air and can thus stably maintain the amount of air entrained even when the time of kneading is prolonged in the production of cement compositions. A further object is to provide a cement admixture having such air entraining properties and having a high level of water-reducing capacity as well as a cement composition.

Abstract: The present invention is thus directed to a cement additive which comprises a copolymer (A) obtained by polymerizing a monomer mixture (K), wherein; said monomer mixture (K) comprises a polyalkylene glycol ester monomer (I) represented by the general formula (1):  a polyalkylene glycol ester monomer (II) represented by the general formula (2):  and a carboxylic acid monomer (III) represented by the general formula (3):

Abstract: It is an object of the present invention to provide a polycarboxylic acid copolymer which improves the water reducing capacity and workability of cement compositions and the like and making them easier to handle when the fluidity and water reducing capacity are at the same levels, a method of producing the copolymer, and a cement additive and a cement composition comprising the copolymer. The present invention is further to provide a polycarboxylic acid copolymer and a cement additive which are capable of improving the strength and durability of hardening products of cement compositions, hence can advantageously be used in ultrahigh strength concrete. The present invention is still further to provide a method of producing polycarboxylic acid copolymers having high water reducing capacity, reducing the viscosity of cement compositions and improving the workability in applying cement.

Abstract: The present invention has for its object to provide an economical cement additive capable of reducing the amount of water to be added to cement compositions and still capable of providing cement compositions with high fluidity, good processability, and a proper level of air-entraining ability resulting from sufficient foaming prevention, at low addition levels, a cement composition in which the above cement additive is used, and a polycarboxylic acid polymer excellent in dispersing effects on cement particles or inorganic powders or pigments and capable of being used with advantage as a cement additive or a dispersant for various uses.

Abstract: It is an object of the present invention to provide a production method of a dehydration reaction product by which the occurrence of troubles in the production step or the degradation in performance characteristics or quality of various chemical products can be suppressed to a satisfactory extent.

Abstract: A method for the production of an esterified product which can prevent the occurrence of a gel-like substance during the separation and removal of the water formed by the reaction in the esterification reaction or during the expulsion of a dehydrating solvent by distillation after the esterification reaction by causing an antigelling agent to act on the distillate and consequently permits efficient production of the esterified product of high quality, and an apparatus therefor are to be provided.