HK1091194B - Cement dispersant and concrete composition containing the dispersant - Google Patents

Description

Cement dispersant and concrete composition containing the same

Technical Field

The present invention relates to a cement dispersant and a concrete composition containing the dispersant. More specifically, the present invention relates to a cement dispersant which is a water-soluble amphoteric copolymer containing an alkylene oxide adduct of a polyamide polyamine having an unsaturated group and two or more types of polyalkylene glycol esters, has a property of increasing dispersibility with time when a cement composition such as concrete is kneaded, and has excellent slump retention properties when used alone or mixed with a conventional additive for mortar and concrete, and a concrete composition containing the dispersant.

Background

As conventional cement dispersants, melamine sulfonates, lignin sulfonates, copolymers of olefins and maleic acid, polycarboxylic acid dispersants, and the like have been used. However, there are problems in work such as long waiting time of raw concrete cars at work sites of large buildings, profit problems such as narrow supply range of raw concrete producing companies in the case of poor slump retention, and quality problems such as long raw concrete transportation time and quality deterioration associated therewith, and there is an increasing demand for slump retention. Although the polycarboxylic acid-based dispersant has excellent slump retention compared with the previous cement dispersant, the polycarboxylic acid-based dispersant has only begun to be firmly stuck in the industry, and at present, the slump retention exceeding that of the conventional cement dispersant is required. In order to meet such a demand, a controlled release polymer capable of realizing slump retention with time has been developed. Disclosed are techniques for a sustained-release cement dispersant such as patent document 1 for granulating a dispersant, patent document 2 and patent document 3 for a hydrolysis-type crosslinked polymer using an alkaline condition in a cement dispersion, and patent document 4 for a sustained-release cement admixture containing polysuccinimide. They still need to be improved in terms of product properties and effects.

On the other hand, patent documents 5 and 6 disclose copolymers containing methacrylic acid esters and acrylic acid esters. However, they have not achieved the slow release performance by the alkaline condition in the cement dispersion.

Further, patent documents 7 and 8 disclose polycarboxylic acid dispersants for high-strength concrete as a copolymer compound containing a polyamide polyamine or an alkylene oxide adduct thereof.

Patent document 1: japanese patent laid-open publication No. Sho 54-139929

Patent document 2: japanese unexamined patent publication Hei 03-075252

Patent document 3: japanese unexamined patent publication Hei 06-157100

Patent document 4: japanese unexamined patent publication Hei 08-169741

Patent document 5: JP-A9-40446

Patent document 6: japanese patent application laid-open No. 3029827

Patent document 7: japanese patent No. 3235002

Patent document 8: japanese patent No. 3336456

Disclosure of Invention

The present invention has been made in view of such circumstances, and an object thereof is to provide a cement dispersant which can maintain stable product performance of a controlled-release polymer, can increase dispersibility with time, has excellent concrete viscosity-lowering properties, and can provide slump with stability with time by using it alone or mixing it with a cement dispersant having poor slump-retaining properties, and a concrete composition containing the same.

The present inventors have conducted extensive studies to solve the above problems and as a result, have found that a water-soluble amphoteric copolymer containing an alkylene oxide adduct of a polyamide polyamine having an unsaturated group and two or more polyalkylene glycol esters is a cement dispersant having excellent slump retention properties and excellent concrete viscosity reducing properties, and have accomplished the present invention.

The present invention relates to a cement dispersant which is composed of a water-soluble amphoteric copolymer obtained by copolymerizing a monomer mixture containing the following compounds as main monomer components, or a partially or completely neutralized salt thereof, and which can increase the dispersing ability with time when added to a concrete composition for kneading:

at least one compound (compound A) obtained by adding 0 to 8 moles of alkylene oxide having 2 to 4 carbon atoms to 1 equivalent of amino residue of a polyamidopolyamine obtained by condensing 0.5 to 0.95 mole of an ester of a polyalkylenepolyamine having 1.0 mole of a dibasic acid or a dibasic acid and a lower alcohol having 1 to 4 carbon atoms and 0.05 to 0.70 mole of acrylic acid or methacrylic acid or an ester of an acrylic acid or methacrylic acid and a lower alcohol having 1 to 4 carbon atoms (compound A), and

at least one compound (compound B) represented by the general formula (1):

(in the formula, R¹Represents a hydrogen atom or a methyl group, M represents a hydrogen atom, an alkali metal, an alkaline earth metal, an ammonium group or an alkanolammonium group), and

at least one compound (compound C) represented by the general formula (2):

(in the formula, R²Represents an alkylene group having 2 to 4 carbon atoms, R³Represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and m is the number of moles of polyalkylene glycol added and represents an integer of 1 to 100), and

at least one compound (compound D) represented by the general formula (3):

CH₂＝CH-COO(R⁴O)nR⁵ (3)

(in the formula, R⁴Represents an alkylene group having 2 to 4 carbon atoms, R⁵Represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and n is the number of addition moles of polyalkylene glycol and represents an integer of 1 to 100).

As described above, the compound A used in the present invention is a compound obtained by adding a specific amount of alkylene oxide (compound d) to a polyamide polyamine obtained by condensing a polyalkylene polyamine (compound a), a dibasic acid or an ester of a dibasic acid and a lower alcohol having 1 to 4 carbon atoms (compound b), an acrylic acid or a methacrylic acid or an ester of an acrylic acid or a methacrylic acid and a lower alcohol having 1 to 4 carbon atoms (compound c) at a specific ratio, and the compound A-polyalkylene polyamine includes, for example, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, dipropylenetriamine, tripropylenetetramine, tetrapropylenepentamine, etc., but from the viewpoint of effect and economy, diethylenetriamine, triethylenetetramine, etc. are preferable, and a compound b-dibasic acid and a lower alcohol ester thereof having 1 to 4 carbon atoms, examples thereof include malonic acid, succinic acid, fumaric acid, maleic acid, glutaric acid, adipic acid, pimelic acid, phthalic acid, azelaic acid, sebacic acid, and lower alcohol esters thereof having 1 to 4 carbon atoms such as methanol, ethanol, propanol, butanol, or isomers thereof if present, among which adipic acid is most preferable from the viewpoint of efficiency and economy, examples of the compound c-acrylic acid or methacrylic acid and lower alcohol esters thereof having 1 to 4 carbon atoms include acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate and the like, polyamide polyamines composed of the three components of the above-mentioned compounds a, b and c can be conveniently obtained by a known polycondensation technique, the alkylene oxide having 2 to 4 carbon atoms as the compound d to be added to the amino residue of the polyamide polyamine means ethylene oxide, propylene oxide or butylene oxide, and these alkylene oxides may be used singly or in combination of two or more.

The polycondensation reaction of the compounds a, b and c in the preparation of the polyamide polyamine may be, for example, a two-step reaction method in which only the compound a and the compound b are first subjected to polycondensation, and then the compound c as a monobasic acid is added to continue the polycondensation, or a one-step reaction method in which the compounds a, b and c are simultaneously mixed from the beginning to perform the polycondensation. However, in any of the methods, since the polycondensation reaction, that is, the amidation reaction and the amide exchange reaction are simultaneously carried out, it is considered that the same result is obtained when the acrylic acid residue or the methacrylic acid residue derived from the compound c is finally positioned at the end of the polyamide chain.

Next, the reaction molar ratio of the above three components constituting the polyamide polyamine will be described. The reaction ratio of the compound b (dibasic acid or ester thereof) is 0.5 to 0.95 mol based on 1 mol of the compound a (polyalkylene polyamine). By reacting at a molar ratio within this range, the polycondensate of the compound a and the compound b is a polyamide having a chain length within a certain range, which is formed by polycondensation at an average ratio of (2 moles of polyalkylene polyamine: 1 mole of dibasic acid) to (20 moles of polyalkylene polyamine: 19 moles of dibasic acid), so that the dispersant formed therefrom can exhibit water-reducing property and slump retention property. When the chain length of the polyamide is shorter (when the reaction ratio is less than 0.5 mol), slump retention of a dispersant formed therefrom is extremely poor. When the chain length is longer (when the above reaction ratio exceeds 0.95 mol), the water-reducing property decreases, and thus it is not preferable.

The polyamide polyamine of the present invention contains acrylic acid residues or methacrylic acid residues in an amount of 0.10 mol [ when a: b: c is 1.0: 0.5: 0.05 (mol) ] to 14 mol [ when a: b: c is 1.0: 0.95: 0.70 (mol) ] per molecule, but is preferably in the range of 0.5 to 2.0 mol from the viewpoint of effect. If this value is less than 0.5 mol (for example, if the amount of compound c is less than 0.25 relative to compound a at a ratio of a: b of 1.0: 0.5), the composition ratio of compound a thus formed in the final copolymer is low, and the performance as a cement dispersant is remarkably lowered. On the other hand, if it exceeds 2.0 mol (for example, if the amount of the compound c is more than 0.10 in terms of a: b of 1.0: 0.95), the copolymer will form too many three-dimensional structures, and sufficient effects cannot be obtained.

As the compound B used in the present invention, acrylic acid or methacrylic acid or their sodium, potassium, ammonium, monoethanolamine, diethanolamine, or triethanolamine salts can be cited, but acrylic acid or methacrylic acid is preferable from the viewpoint of performance and economy.

As the form of the compound B after being incorporated into the final copolymer, an acid and/or a (partially or completely) neutralized salt formed of sodium, potassium, ammonium, alkanolamine are preferable from the viewpoint of water solubility.

Examples of the compound C used in the present invention include methacrylic acid esters of methoxypolyethylene glycol, methacrylic acid esters of ethoxypolyethylene glycol, methacrylic acid esters of ethylene oxide/propylene oxide adducts of lower alcohols, monomethacrylate esters of polyethylene glycol, and the like. When two or more oxyalkylene groups are used simultaneously, random addition or block addition may be carried out.

Examples of the compound D used in the present invention include acrylic acid esters of methoxypolyethylene glycol, acrylic acid esters of ethoxypolyethylene glycol, acrylic acid esters of ethylene oxide/propylene oxide adducts of lower alcohols, and monoacrylic acid esters of polyethylene glycol. When two or more oxyalkylene groups are used simultaneously, random addition or block addition may be carried out.

The blending ratio of the compound C and the compound D used in the present invention is not particularly limited, and when the total is 100% by weight, the compound C: when the compound D is 5 to 95: 5 to 95 wt%, the compound C: the compound D is particularly preferably 10 to 70: 30 to 90 wt%.

The preparation method for forming the compound is by a well-known esterification manufacturing technique. The known esterification production technique is a production method which can be carried out in the field or other fields, and includes a production method in which (meth) acrylic acid and polyalkylene glycol are dehydrated directly or in the presence of a solvent, a method in which alkylene oxide is added to (meth) acrylic acid, a method in which (meth) acryloyl halide or (meth) acrylic anhydride is reacted with polyalkylene glycol, and the like.

As other copolymerizable monomers other than compound A, B, C, D of the present invention, the following known monomers can be mentioned. These monomers are (non) aqueous monomers: methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, styrene, and the like, anionic monomers: itaconic acid, maleic acid (anhydride), vinylsulfonic acid, styrenesulfonic acid, and the like, amide-based monomers: acrylamide, alkylene oxide adduct of acrylamide, etc., polyalkylene glycol monomer: alkylene oxide adducts of allyl alcohol, monoesters or diesters of polyalkylene glycols with maleic anhydride, esters of polyalkylene glycols with itaconic acid, and the like.

The blending ratio of the other copolymerizable monomer is 30% by weight or less, preferably 20% by weight or less, and more preferably 10% by weight or less of the total monomer added.

From the viewpoint of the effect, the mixing ratio of the compound A, the compound B, the compound C and the compound D used in the present invention is preferably 5 to 25% by weight, 1 to 20% by weight, 10 to 70% by weight, and the total amount is 100% by weight.

The production method for obtaining the water-soluble amphoteric copolymer of the present invention is not particularly limited, and for example, a known polymerization method such as solution polymerization or bulk polymerization using a polymerization initiator can be used.

The solution polymerization method may be carried out either batchwise or continuously, and examples of the solvent used therein include water, alcohols: methanol, ethanol, isopropanol, etc., aromatic or aliphatic hydrocarbons: benzene, toluene, xylene, cyclohexane, n-hexane, etc., ester or ketone compounds: ethyl acetate, acetone, methyl ethyl ketone, etc., cyclic ether compounds: tetrahydrofuran, dioxane, etc., but from the viewpoint of solubility of the raw material monomer and the copolymer formed, at least one of water and a lower alcohol having 1 to 4 carbon atoms is preferably used, and water is more preferably used as the solvent.

In the case of aqueous solution polymerization, as the radical polymerization initiator, a water-soluble polymerization initiator such as persulfate type: ammonium persulfate, sodium persulfate, potassium persulfate, etc., hydrogen peroxide, azoamidine compounds: 2, 2' -azobis-2-methylpropionamidine hydrochloride, cyclic azoamidine compounds: 2, 2' -azobis-2- (2-imidazolin-2-yl) propane hydrochloride, and the like, water-soluble azo compounds: azonitrile compounds such as 2-carbamoylazoisobutyronitrile, and in this case, alkali metal sulfites such as sodium bisulfite, pyrosulfites, sodium hypophosphite, Fe (II) salts such as Mohr's salt, dihydrate of sodium hydroxymethanesulfonate, hydroxylamine salts, thiourea, L-ascorbic acid (salt), and erythorbic acid (salt) may be used in combination.

In addition, in solution polymerization using a lower alcohol, an aromatic or aliphatic hydrocarbon, an ester compound or a ketone compound as a solvent, peroxides: benzoyl peroxide, lauroyl peroxide, sodium peroxide, and the like, hydroperoxides: t-butyl hydroperoxide, cumene hydroperoxide, etc., azo compounds: azobisisobutyronitrile and the like as a radical polymerization initiator. In addition, an accelerator such as an amine compound may be used in combination. When a water-lower alcohol mixed solvent is used, the above-mentioned various radical polymerization initiators or a combination of a radical polymerization initiator and an accelerator can be appropriately selected and used.

In the case of bulk polymerization, as the radical polymerization initiator, peroxides: benzoyl peroxide, lauroyl peroxide, sodium peroxide, and the like, hydroperoxides: t-butyl hydroperoxide, cumene hydroperoxide, etc., azo compounds: azobisisobutyronitrile, and the like.

The reaction temperature in the copolymerization is not particularly limited, and for example, a reaction temperature in the range of 30 to 95 ℃ is suitable when persulfate is used as an initiator.

Chain transfer agents may be used in the copolymerization. As the chain transfer agent, a thiol chain transfer agent such as mercaptoethanol, thioglycerol, thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiomalic acid, octyl thioglycolate, octyl 3-mercaptopropionate, or 2-mercaptoethanesulfonic acid may be used, or two or more kinds of chain transfer agents may be used in combination.

The polymerization time in the copolymerization is not particularly limited, and for example, 0.5 to 10 hours is preferable, 0.5 to 8 hours is preferable, and 0.5 to 6 hours is more preferable. If the polymerization time is shorter or longer than this range, the polymerization rate will be low and the productivity will be poor, and therefore it is not preferable.

The method of dropping the monomers during the copolymerization is not particularly limited, and examples thereof include a method of adding a part or all of the monomers to a reaction vessel and dropping an initiator, a method of adding one or more monomers to a reaction vessel and dropping another monomer, an initiator, a chain transfer agent, and the like, a method of dropping a monomer mixture, a radical polymerization initiator, and a chain transfer agent separately, and a method of dropping a mixture of each monomer and a chain transfer agent separately and a method of dropping a radical polymerization initiator separately, as disclosed in Japanese patent application No. 3235002 and Japanese patent application No. 3336456. There is also a method of shifting the timing of addition of each monomer depending on the reactivity of each monomer.

The molecular weight of the water-soluble amphoteric copolymer obtained in the present invention is not particularly limited, and the weight average molecular weight (gel permeation chromatography, in terms of polyethylene glycol) may be 3,000 to 500,000, and if it is outside this range, the water-reducing ability and slump retention ability are lost.

The present inventors have repeatedly studied various copolymers and as a result, have found that a water-soluble amphoteric copolymer containing a polyamide polyamine alkylene oxide adduct having a reactive group and two or more polyalkylene glycol esters can be used as the cement dispersant of the present invention which can exhibit excellent slump retention properties and concrete viscosity reducing effects. It is believed that the cationic group moiety having a specific amide group of the present invention exerts a certain charge control effect, and the hydrophilic effect of the terminal hydroxyl group of the polyamide polyamine group is also related to the effect. Further, it is believed that the combination of two or more polyalkylene glycol esters (methacrylic acid ester and acrylic acid ester) and the molecular weights of the polyalkylene glycol esters thereof, which are highly regulated in hydrolysis rate under alkaline conditions of the cement dispersion, imparts various slow-release effects. It is believed that the excellent effects of increasing the dispersibility with time and decreasing the concrete viscosity are achieved by this synergistic effect, but the principle cannot be specifically understood. However, since the cement dispersant of the present invention has the following characteristics: since the polymer has a chemical structure of a hydrolyzable site (acrylate), it is inexpensive, free to synthesize by freely adjusting the hydrolyzable site, and excellent in production and product stability since there is no fear of formation of a three-dimensional structure.

Effects of the invention

According to the above detailed description, the water-soluble amphoteric copolymer containing a polyamide polyamine alkylene oxide adduct and two or more polyalkylene glycol esters has an effect of reducing the viscosity of concrete, has low initial adsorption to cement when mixed into a concrete composition and kneaded, and has so-called controlled-release properties in which the dispersibility increases with time. By using the cement dispersant of the present invention alone or in combination with other cement dispersants, excellent slump stability performance over time can be imparted, and the quality of green concrete can be maintained without being impaired for a long period of time. In addition, the present invention can use the above water-soluble amphoteric copolymer alone or in combination with other cement dispersants as a high-performance AE water reducing agent.

Best Mode for Carrying Out The Invention

The amount of the cement dispersant composed of the water-soluble amphoteric copolymer of the present invention added varies depending on the mixing conditions of the concrete materials to be contained, but is about 0.1 to 1.5% in terms of solid content with respect to cement, that is, in order to obtain water-reducing ability and slump retention, the addition amount is preferably as large as possible, but if the addition amount is too large, coagulation delay is caused, and in the worst case, hardening failure is caused. For example, ordinary portland cement, early strength portland cement, low-heat and medium-heat portland cement, slag cement, silica fume cement, and VKC-100SF aggregate, i.e., fine aggregate and coarse aggregate, and mixed materials, for example, silica fume, fly ash, calcium carbonate powder, blast furnace slag powder, an expansion material, and water.

The concrete compositions listed above are various and the mixing ratio thereof is also the same. The performance requirements often cannot be sufficiently satisfied by using only one kind of the corresponding specific cement dispersant, and cement dispersants having different performance properties are often used in combination. The cement dispersant of the present invention can be used as a main agent of the cement dispersant, or as an auxiliary agent of a cement dispersant having poor slump retention. The cement dispersant can be mixed with a common cement dispersant according to any proportion, and the proportion is 1-99/99-1 wt%. The conventional cement dispersant is a known cement dispersant, and examples thereof include salts of polycarboxylic acid copolymers such as Japanese patent publication No. 58-383380, Japanese patent publication No. 59-18338, Japanese patent publication No. 2628486, Japanese patent publication No. 2774445, Japanese patent publication No. 3235002 and Japanese patent publication No. 3336456, salts of naphthalene sulfonic acid condensates, salts of melamine sulfonic acid condensates and lignosulfonates.

In order to obtain a concrete composition in a good state, the above-mentioned air-entraining agent, setting retarder, accelerator, separation inhibitor, thickener and the like can be usually blended. In the present specification, a cement dispersant and a preparation containing the dispersant are referred to as other additives for mortar and concrete.

Accordingly, the present invention also provides an admixture for mortar and concrete which is a composition comprising the cement dispersant of the present invention and the above-mentioned other additives for mortar and concrete, and a concrete composition containing the admixture for mortar and concrete.

Specific examples of the air-entraining agent as an additive for mortar and concrete include (1) an anionic air-entraining agent, (2) a nonionic air-entraining agent, and (3) an amphoteric air-entraining agent. Examples of (1) the anionic air-entraining agent include sulfuric acid ester salts of higher alcohols (or alkylene oxide adducts thereof), resin soap salts such as alkylbenzenesulfonic acid salts and rosin soaps, and phosphoric acid ester salts of higher alcohols (or alkylene oxide adducts thereof), examples of (2) the nonionic air-entraining agent include polyalkylene glycols, alkylene oxide adducts of higher alcohols, esters of fatty acids and polyalkylene glycols, and alkylene oxide adducts of sugar alcohol fatty acid esters, and examples of (3) the amphoteric air-entraining agent composed of anions and cations include alkylbetaine-type, alkylamidobetaine-type, and amino acid-type amphoteric active agents. The preferable addition amount of the air-entraining agent is 0 to 1 wt% based on the cement dispersant.

As concrete examples of the defoaming agent as another additive for mortar and concrete, there can be mentioned (1) an active agent type defoaming agent, (2) a silicone type defoaming agent and (3) a mineral oil type defoaming agent, and as the (1) active agent type defoaming agent, there are exemplified polyalkylene glycol, an alkylene oxide adduct of higher alcohol, an ester of an alkylene oxide adduct of higher alcohol and a fatty acid, an ester of polyalkylene glycol and a fatty acid, etc., as the (2) silicone type defoaming agent, dimethyl silicone, a silicone emulsion, etc., and as the (3) mineral oil type defoaming agent, mineral oil emulsion, paraffin emulsion, higher alcohol emulsion, etc.

Specific examples of the setting retarder as an additive for mortar and concrete include (1) inorganic setting retarders: phosphates, fluorides of silicon, zinc oxide, zinc carbonate, zinc chloride, zinc oxide, copper hydroxide, magnesium salts, borax, boron oxide, (2) organic coagulation retarders: phosphonic acid derivatives, saccharides and derivatives thereof, hydroxycarboxylic acid salts, and lignosulfonic acid salts, more specifically exemplified are phosphonic acid derivatives: amino tri (methylene phosphonic acid), amino tri (methylene phosphonic acid) pentasodium salt, 1-hydroxyethylidene-1, 1-diphosphonic acid, ethylene diamino tetra (methylene phosphonic acid), diethylene triamino penta (methylene phosphonic acid) and phosphonic acids and derivatives of alkali metal salts, alkaline earth metal salts, sugars: sucrose, maltose, raffinose, lactose, glucose, fructose, mannose, arabinose, xylose, アビト - ス, ribose, hydroxycarboxylate: gluconic acid, citric acid, glucoheptonic acid, malic acid, tartaric acid, their alkali metal salts, alkaline earth metal salts, the additive is preferably added in an amount of 0 to 30 parts by weight based on the binder such as cement.

Examples of the accelerator as an additive for mortar and concrete include inorganic accelerators represented by calcium chloride and calcium nitrite, and organic accelerators represented by alkanolamines. The additive is preferably added in an amount of 0 to 20 parts by weight based on the binder such as cement.

Examples of the thickener/separation inhibitor as an additive for mortar and concrete include (1) a cellulose-based water-soluble polymer: cellulose ether (MC, etc.), (2) polyacrylamide-based water-soluble polymer: polyacrylamide, (3) biopolymer: カ - ドラン, Welan gum, (4) nonionic tackifier: fatty acid diesters of polyalkylene glycols, urethane condensates of polyalkylene glycols, and the like. The preferable mixing ratio of the additive is 0 to 1.5 wt% relative to the concrete composition.

Examples

Next, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Synthesis of Water-soluble amphoteric copolymer

Example 1

< Process for producing Compound A-1 >

103g (1.00 mol) of diethylenetriamine and 97.3g (0.67 mol) of adipic acid were charged into a reaction vessel equipped with a stirrer, and stirred and mixed under a nitrogen atmosphere by introducing nitrogen gas. The temperature was raised to 150 ℃ and water produced in the reaction was removed at the same time as the polycondensation, and the reaction was carried out for 20 hours until the acid value became 22. Then, 1.1g of hydroquinone methyl ether and 27.5g (0.32 mol) of methacrylic acid were added thereto, and the mixture was reacted at the same temperature (150 ℃ C.) for 10 hours. Thus, a total of 42g of distilled water from the reaction and 187g of polyamide polyamine (melting point 122 ℃ C., acid value 23) were obtained. The polyamide polyamine was dissolved in 272g of water and the temperature was raised to 50 ℃. Further, 220g (equivalent to 3.0 moles based on the total amount of amino residues including unreacted amino groups) of ethylene oxide was gradually introduced at the same temperature (50 ℃) over 4 hours, and aging was conducted for 2 hours. 680g of Compound A-1 (60% solids) according to the invention were thus obtained.

< preparation method 1 of example 1>

Next, 314g of water was charged into a reaction vessel equipped with a stirrer, nitrogen gas was introduced into the reaction vessel to make the inside of the synthesis system a nitrogen atmosphere, and the temperature was raised to 80 ℃. Then, a mixture of 61g of water, 6.0g of acrylic acid (compound B-1), 18.7g of methacrylic acid (compound B-2), 169g of methoxypolyethylene glycol monomethacrylate (compound C, molecular weight: about 2000) and 169g of methoxypolyethylene glycol monoacrylate (compound D, molecular weight: about 1000), 78.4g of a 5% ammonium thioglycolate aqueous solution and 78.4g of a 5% ammonium persulfate aqueous solution were simultaneously added dropwise to the synthesis system within 2 hours. After completion of the dropwise addition, 142.7g of Compound A was further added dropwise over 30 minutes, and 39.2g of a 5% aqueous ammonium persulfate solution was further added dropwise over 1 hour. (if expressed as a weight ratio of solid matter, the ratio of compound a/compound B (the total of compound B-1 and compound B-2)/compound C/compound D is 6 wt%/8 wt%/43 wt% and total 100 parts by weight), followed by aging for 2 hours, cooling, and neutralization with a 48% aqueous NaOH solution to a pH of 6, to obtain 1,000g of a water-soluble amphoteric copolymer. When the molecular weight was measured by GPC, the weight average molecular weight of the copolymer was 42,000. The measurement conditions were as follows.

Column: ohpak SB-803HQ, Ohpak SB-804HQ (manufactured by Showa electric Co., Ltd.)

Eluent: the ratio of 50mM sodium nitrate aqueous solution to acetonitrile is 80 wt.% (wt.%) to 20 wt.% (wt.%)

A detector: differential refractometer

Standard curve: polyethylene glycol

< preparation method 2 of example 1>

Next, 314g of water was charged into a reaction vessel equipped with a stirrer, nitrogen gas was introduced into the reaction vessel to make the inside of the synthesis system a nitrogen atmosphere, and the temperature was raised to 80 ℃. Then, a mixed solution of 61g of water, 6.0g of acrylic acid (compound B-1), 18.7g of methacrylic acid (compound B-2), 169g of methoxypolyethylene glycol monomethacrylate (compound C, molecular weight about 2000), 169g of methoxypolyethylene glycol monoacrylate (compound D, molecular weight about 1000) and 78.4g of a 5% ammonium thioglycolate aqueous solution, and 78.4g of a 5% ammonium persulfate aqueous solution were simultaneously dropped into the synthesis system within 2 hours. After completion of the dropwise addition, 142.7g of Compound A was further added dropwise over 30 minutes, and 39.2g of a 5% aqueous ammonium persulfate solution was further added dropwise over 1 hour. (if expressed as a weight ratio of solid matter, the ratio of compound a/compound B (the total of compound B-1 and compound B-2)/compound C/compound D is 6 wt%/8 wt%/43 wt% and total 100 parts by weight), followed by aging for 2 hours, cooling, and neutralization with a 48% aqueous NaOH solution to a pH of 6, to obtain 1,000g of a water-soluble amphoteric copolymer. The weight average molecular weight of the copolymer was 41,000 when the molecular weight was measured by GPC. The GPC measurement conditions were as follows:

column: ohpak SB-803HQ, Ohpak SB-804HQ (manufactured by Showa electric Co., Ltd.)

Eluent: the ratio of 50mM sodium nitrate aqueous solution to acetonitrile is 80 wt.% (wt.%) to 20 wt.% (wt.%)

A detector: differential refractometer

Standard curve: polyethylene glycol

The same results are given in preparation 1 and preparation 2 of the examples. Copolymers of the following examples and comparative examples were prepared according to preparation method 1 of example 1.

Examples 2 to 9

In the same manner as in example 1, polyamide polyamine alkylene oxide adducts A-2 to A-6 were obtained from the starting materials shown in Table 1. Further, a water-soluble amphoteric copolymer (examples 2 to 9) was obtained by copolymerization of the compound a, the compound B, the compound C and the compound D shown in table 2 in the same manner as in example 1 (except that the water content was adjusted so that the solid content of the obtained copolymer was 40%).

[ Table 1]

Synthesis examples of Compounds A-1 to A-6 1

1 Components (a) to (d) used for preparing Compound A in the tables correspond to the above-mentioned Compounds a to d, and each numerical value represents a compositional molar ratio

2 diethylene triamine

3 triethylene tetramine

Acid value of condensate (intermediate condensate) of 4 compound a and compound b

Acid value of 5 condensate (final condensate) of Compound a, Compound b and Compound c

N.d. indicates that no measurement is possible because dibasic acid esters are used.

[ Table 2]

Examples 1 to 9 x 1

The calculation method of the mixture ratio comprises the following steps: to determine the proportions of the monomers in the copolymer obtained, compound B is calculated as a salt.

Example 1 composition calculation example

Compound A-1: 42.7g (solid content 42.7X 0.6-25.6),

compound B-1: 6.0g (solid content 94 (molecular weight of sodium acrylate) × 6.0g/72 (molecular weight of acrylic acid) ═ 7.8g)

Compound B-2: 18.7g (solid content: 108 (molecular weight of sodium methacrylate) × 18.7g/86 (molecular weight of methacrylic acid) ═ 23.5g)

Compound C: 169g, compound D: 169g, 100% solids.

A compound A: compound B (total of Compound B-1 and Compound B-2): compound C: compound D25.6: 31.3: 169 (solids) 6: 8: 43 wt%

The values of the compounds A to C in Table 1 are parts by weight of the composition based on the solid content

Sodium acrylate 2

Sodium methacrylate 3

4 methoxy polyethylene glycol methacrylate (molecular weight 250)

5 methoxy polyethylene glycol methacrylate (molecular weight 1000)

6 methoxy polyethylene glycol methacrylate (molecular weight 2000)

7 methoxy polyethylene glycol methacrylate (molecular weight 4000)

8 methoxy polyethylene glycol acrylate (molecular weight 250)

9 methoxy polyethylene glycol acrylate (molecular weight 400)

10 methoxy polyethylene glycol acrylate (molecular weight 1000)

Comparative examples 1 to 4

Condensation compounds (compound a '-1 to compound a' -4) were synthesized in the same manner as in example 1, except that the reaction ratio of the polyalkylene polyamine, the dibasic acid and the (meth) acrylic acid was changed from the scope of the present invention. The synthesis examples are shown in table 3. Then, these compounds A-1, A '-1 to A' -4 were copolymerized with the compound B, the compound C and the compound D to obtain water-soluble amphoteric copolymers (comparative examples 1 to 7). Examples of the synthesis thereof are shown in Table 4.

[ Table 3]

Synthesis examples of Compounds A '-1 to A' -4 (control Compounds). 1

1 Components (a) to (d) used for preparing Compound A' in the tables correspond to the above-mentioned Compounds a to d, and each numerical value represents a compositional molar ratio

2 diethylene triamine

3 triethylene tetramine

Acid value of condensate (intermediate condensate) of 4 compound a and compound b

Acid value of 5 condensate (final condensate) of Compound a, Compound b and Compound c

[ Table 4]

Comparative examples 1 to 7 x 1

The formulation was determined according to the formulation calculation method of table 2.

In table 1, values of compound a', compound B, compound C and compound D are parts by weight of the composition based on solid matter.

Sodium acrylate 2

Sodium methacrylate 3

4 methoxy polyethylene glycol methacrylate (molecular weight 250)

5 methoxy polyethylene glycol methacrylate (molecular weight 1000)

6 methoxy polyethylene glycol methacrylate (molecular weight 2000)

7 methoxy polyethylene glycol acrylate (molecular weight 250)

8 methoxy polyethylene glycol acrylate (molecular weight 400)

9 methoxy polyethylene glycol acrylate (molecular weight 1000)

10 if the copolymer does not contain compound a', the water-reducing property and slump stability are significantly reduced with time.

< mortar flow test >

Mortars were prepared using the cement dispersants (1) to (9) of the present invention and the control cement dispersants (1) to (7), and their flow values were measured.

Mortar flow test method

200g of ordinary portland cement (manufactured by Pacific セメント Co.) and 260g of silica sand No. 6 (manufactured by Japanese プラスタ -Co.) were weighed and subjected to air refining for 90 seconds. Further, 0.448g (based on solid matter) of the copolymer obtained in examples 1 to 9 and comparative examples 5 to 7 was weighed, and the copolymer was diluted with water to 90g in total to obtain water for kneading (water/cement ratio: 45%, sand/cement ratio: 130%). The mixture of cement and sand was put into kneading water and mixed for 180 seconds to prepare a mortar. It is important to note that the mixing conditions of the air-mix and mortar are always uniform.

Mortar flow measurement and measurement results

The prepared mortar was poured into a phi 50mm × H50mm hollow cylindrical container on an acrylic resin plate, and filled until the upper end of the container was filled. Immediately after filling, the hollow cylindrical container was lifted up in a direction perpendicular to the acrylic resin plate at a constant speed. When the expansion of the mortar completely stopped, the maximum expansion diameter of the mortar and the diameter perpendicular thereto were measured, and the average of these two values was obtained. This operation was also carried out after 60 minutes, 120 minutes and 180 minutes after the mortar preparation. However, when the measurement was performed at each time, kneading was performed for 90 seconds. In addition, in the measurement from immediately after kneading until after 180 minutes, the vessel containing the mortar was left to stand with a plastic cloth to avoid evaporation of water.

< mortar flow test results >

[ Table 5]

Mortar flow test results

Mortar flow test results: examples 1 to 9 showed slower achievement of the dispersing effect and improved dispersibility with time, as compared with comparative examples 5 to 7.

< measurement of adsorption quantity >

The supernatant liquid of the mortar prepared according to the mortar flow test was filtered, and the amount of organic carbon in the filtered water was measured to calculate the adsorption rate on cement.

x all-organic carbon tester: TOC-5000A manufactured by Shimadzu

The method for measuring the adsorption rate of the cement comprises the following steps: the cement adsorption rate { (amount of organic carbon element in water containing cement dispersant of the present invention prepared before preparation of mortar) - (amount of organic carbon element in filtered water obtained by suction filtration of mortar) } × 100/(amount of organic carbon element in water containing cement dispersant of the present invention prepared before preparation of mortar)

[ Table 6]

Measurement result of adsorption amount of Cement dispersant

	After 60 minutes	After 120 minutes	After 180 minutes
				Example 7	6％	17％	23％
Comparative example 6	33％	39％	40％

The cement dispersant of the present invention tends to increase the adsorption amount of cement with time and to improve the mortar dispersibility. On the other hand, the adsorption amount in comparative example 6 hardly changed, and the dispersing ability of mortar was also lowered faster than that of the cement dispersant of the present invention.

Evaluation of Water-soluble amphoteric copolymer by concrete test

I. When the water-soluble amphoteric copolymer is used alone

Here, the evaluation of the water-soluble amphoteric copolymer used alone was to carry out a concrete test. The concrete was kneaded using a 55-liter biaxial forced mixer, water in which a water-soluble amphoteric copolymer cement dispersant was dissolved was added to the cement and the fine aggregate, and the mixture was kneaded for 60 seconds, and then the coarse aggregate was put into the mixer and kneaded for 90 seconds. The properties of the fresh concrete immediately after the discharge of the concrete, after 1 hour and after 2 hours (slump flow JIS a 1150, air amount JIS a 1128) were determined. The test was carried out for the compressive strength (JIS A1108).

[ Table 7]

Mixing of concrete

*¹Tap water

*²Low heat portland cement (density 3.22 g/cm)³)

*³Lusha (Junjin produced, density 2.63 g/cm)³)

*⁴Limestone macadam (bird shape mountain product, density 2.70 g/cm)³)

[ Table 8]

Concrete test results

*¹Represents the amount (solid content) of the cement dispersant added based on the mass of cement, and the unit is weight%

[ Table 9]

Compressive strength results

The water-soluble amphoteric polymer of the present invention has a controlled release property in which slump is increased with time, and is stable and low in concrete viscosity. The limit of the concrete transporting time in a sample JASS 5(1997) was 120 minutes, which was a working float, issued by japan architecture society (japan) and was not less than this value, and the dispersant of the present invention was a cement dispersant having stable slump retention property without any problem.

II. Concrete test results when water-soluble amphoteric copolymer is used in admixture with other cement dispersant

Here, concrete test 1 using low-heat portland cement and concrete test 2 using ordinary portland cement were evaluated when the water-soluble amphoteric copolymer was used in admixture with other cement dispersants. The concrete was kneaded using a 55-liter biaxial forced mixer, water in which the water-soluble amphoteric copolymer cement dispersant and other cement dispersants were dissolved was added to the cement and the fine aggregate, and the mixture was kneaded for 60 seconds, and then the coarse aggregate was put into the mixer and kneaded for 90 seconds. The properties of the fresh concrete immediately after the discharge of the concrete, after 1 hour and after 2 hours (slump flow JIS a 1150, air amount JIS a 1128) were determined. Further, the compression strength (JIS A1108) was measured.

Concrete test 1

[ Table 10]

Mixing of concrete

*¹Tap water

*²Low heat portland cement(Density 3.22 g/cm)³)

*³Land sand (density 2.63 g/cm)³)

*⁴Limestone macadam (density 2.70 g/cm)³)

[ Table 11]

Concrete test results

*¹Represents the amount (solid content) of the cement dispersant added based on the mass of cement, and the unit is weight%

*²Example 1: comparative example 6 ═ 70: 30 (parts by weight)

[ Table 12]

Compressive strength results

*¹Example 1: comparative example 6 ═ 70: 30 (parts by weight)

When the cement dispersant of the present invention is used in combination with another cement dispersant, stable slump fluidity can be ensured, the concrete viscosity is low, and there is no problem in hardening.

Concrete test 2

[ Table 13]

Mixing of concrete

*¹Tap water

*²Ordinary Portland cement (density 3.15 g/cm)³)

*³Land sand (density 2.63 g/cm)³)

*⁴Hard macadam (density 2.65 g/cm)³)

[ Table 14]

Concrete test results

*¹Represents the amount (solid content) of the cement dispersant added based on the mass of cement, and the unit is weight%

*²Example 7: comparative example 6 ═ 50: 50 (parts by weight)

[ Table 15]

Compressive strength results

*¹Example 7: comparative example 6 ═ 50: 50 (parts by weight)

When the cement dispersant of the present invention is used in combination with another cement dispersant, the stability of slump fluidity with time can be secured even if the type of cement is changed, and the concrete viscosity is small.

Claims (4)

1. A cement dispersant which comprises a water-soluble amphoteric copolymer obtained by copolymerizing a monomer mixture containing the following compounds as the main monomer components, or a partially or completely neutralized salt thereof, and which can increase the dispersing ability with time when added to a concrete composition for kneading:

at least one compound A obtained by adding 0 to 8 moles of alkylene oxide having 2 to 4 carbon atoms to 1 equivalent of amino residue of polyamidopolyamine formed by condensation of 0.5 to 0.95 mole of ester of polyalkylenepolyamine formed by 1.0 mole of dibasic acid or dibasic acid and lower alcohol having 1 to 4 carbon atoms and 0.05 to 0.70 mole of ester of acrylic acid or methacrylic acid or acrylic acid and lower alcohol having 1 to 4 carbon atoms, and

at least one compound represented by the general formula (1), i.e., compound B:

[ solution 1]

In the formula, R¹Represents a hydrogen atom or a methyl group, M represents a hydrogen atom, an alkali metal, an alkaline earth metal, an ammonium group or an alkanolammonium group, and

at least one compound represented by the general formula (2), i.e., compound C:

[ solution 2]

In the formula, R²Represents an alkylene group having 2 to 4 carbon atoms, R³Represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and m is the number of moles of polyalkylene glycol added and represents an integer of 1 to 100, and

at least one compound represented by the general formula (3), i.e., compound D:

[ solution 3]

CH₂＝CH-COO(R⁴O)nR⁵ (3)

In the formula, R⁴Represents an alkylene group having 2 to 4 carbon atoms, R⁵Represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and n is the number of moles of polyalkylene glycol added and represents an integer of 1 to 100.

2. A cement dispersant as claimed in claim 1, which comprises a compound A to a compound D in the following ratio: compound B: compound C: 5-25% by weight of compound D: 1-20 wt%: 10-70 wt%: a water-soluble amphoteric copolymer obtained by copolymerizing a monomer mixture mixed in a proportion of 10 to 70 wt% and 100 wt% in total, or a partially or completely neutralized salt thereof.

3. An admixture for mortar and concrete, which is a mixture of the cement dispersant of claim 1 or 2 and at least one additive for mortar and concrete selected from the group consisting of other cement dispersants, defoaming agents and air-entraining agents.

4. A concrete composition comprising the cement dispersant according to claim 1 or 2 or the admixture for mortar and concrete according to claim 3.