JP7120988B2 - Powder dispersant composition for hydraulic composition - Google Patents

Description

The present invention relates to a powder dispersant composition for hydraulic compositions.

In recent years, the deterioration of major infrastructure built during the high economic growth period in Japan has become apparent, and we are about to enter the era of major infrastructure renewal and renovation. In particular, demand is expected to grow in the field of repair and reinforcement, and in this field, the use of repair materials that are premixed with a hydraulic composition and a powdery dispersant (hereinafter referred to as a powdery dispersant) is increasing. mainstream.

Powder dispersants premixed in repair materials include naphthalenesulfonic acid-based dispersants, polycarboxylic acid-based dispersants, and melamine sulfonic acid-based dispersants. Polycarboxylic acid-based dispersants are blended with high dispersibility. It is highly rated for its ability to reduce the amount added and its compatibility with polymeric thickeners such as methyl cellulose.

Methods for pulverizing the powder dispersant include a thin film drying method represented by a drum drying method, a disk drying method and a belt drying method, a spray drying method, a kneader method, an inorganic powder supporting method, and the like. Especially important in the pulverization process are the melting point and vitrification temperature of the dispersing agent. In comparison, polycarboxylic acid-based powder dispersants with a large average EO addition mole number of EO graft chains, which are steric repulsion groups, have a high solidification point, so they are excellent in thin film moldability and pulverization during cooling, and are relatively difficult to pulverize. Easy.

In Patent Document 1, a monomer containing an alkoxypolyalkylene glycol mono(meth)acrylic acid ester monomer and a (meth)acrylic acid-based monomer as main components, a chain transfer agent and a polymerization initiator are used to prepare a cement additive. A method for producing a cement additive is disclosed in which a reactor having a reactor with a bottom bearing type agitator is used to continuously perform polymerization and pulverization in the production of cement additives.

Japanese Patent Application Laid-Open No. 2003-119059

A powdery dispersant for a hydraulic composition has advantages such as being premixable and excellent in handleability. , there is a problem that sufficient dispersibility and kneading property (kneading property) cannot be expressed as a result of lower solubility in water.

The present invention provides a powdery dispersant composition for a hydraulic composition that solves the problem of producing a hydraulic composition with a low water-to-powder ratio. That is, to provide a powdery dispersant composition for a hydraulic composition, which is excellent in dispersibility of the hydraulic composition powder and capable of imparting excellent kneadability to the slurry, for example, shortening the kneading time. do.

The present invention provides a powder dispersant composition for a hydraulic composition containing a copolymer having a structural unit (1) represented by the following formula (1) and a structural unit (2) represented by the following formula (2) being a thing,
Median diameter (D50) is 1 μm or more and 90 μm or less,
The proportion of particles with a particle size of 1 μm or more and 250 μm or less is 90% by mass or more and 100% by mass or less.
The present invention relates to a powder dispersant composition for hydraulic compositions.

(wherein R ¹ and R ³ are the same or different and each represent a hydrogen atom or a methyl group, R ² and R ⁴ are the same or different and each a hydrogen atom or an alkyl group having 1 to 3 carbon atoms , M represents a hydrogen atom, an alkali metal, an alkaline earth metal, ammonium or organic ammonium, p represents a number of 0 or more and 2 or less, q represents the number of 0 or 1, and n is the average number of added moles indicates a number between 5 and 150.)

The present invention also relates to a hydraulic composition obtained by blending water, hydraulic powder, and the powdery dispersant composition for a hydraulic composition of the present invention.

ADVANTAGE OF THE INVENTION According to this invention, the dispersing agent composition for hydraulic compositions of powder form which solves the problem at the time of the hydraulic composition manufacturing with a low water powder ratio is provided. That is, there is provided a dispersant composition for a hydraulic composition in powder form, which is excellent in dispersibility of the hydraulic composition powder and capable of imparting excellent kneadability to the slurry.

The powder dispersant composition for a hydraulic composition of the present invention is a powder having a median diameter (D50) of 1 μm or more and 90 μm or less and a proportion of particles having a particle size of 1 μm or more and 250 μm or less of 90% or more and 100% or less by mass. A dispersant composition. The powder dispersant composition of the present invention can be obtained, for example, by drying a mixture containing the predetermined copolymer and water, such as an aqueous solution.
Here, regarding the powdery dispersant composition for hydraulic compositions of the present invention, powder means solid particles including granular, flake-like, pellet-like, granular and the like. The shape of the powder may be regular or irregular.

The present inventors have found that when a powdery polycarboxylic acid-based dispersant having a small particle size and a predetermined particle size distribution is applied in a region having a low water/powder ratio, the hydraulic composition powder exhibits excellent dispersibility. , it was found that excellent kneadability can be imparted to the slurry when it is made into a hydraulic composition. The reason for the improvement in kneadability is not necessarily clear, but due to the small median diameter and low proportion of coarse particles, the increased surface area promotes the hydration of water molecules, resulting in improved solubility in aqueous solvents. As a result of the improvement in , it is possible to act more effectively on the hydraulic composition. The above effect of the present invention can be remarkably recognized in a low water/powder ratio range, but the water/powder ratio at which the effect of the present invention can be obtained is not limited to this range.

The powder dispersant composition for a hydraulic composition of the present invention has a median diameter (D50) of 1 μm or more, preferably 10 μm or more, from the viewpoint of kneadability and handling of the powder dispersant when it is made into a hydraulic composition. , more preferably 20 μm or more, and 90 μm or less, preferably 80 μm or less, more preferably 70 μm or less. The median diameter (D50) was measured using a laser diffraction/scattering particle size distribution analyzer LA-300 (manufactured by Horiba, Ltd.) and ethanol (ethanol (95), manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a dispersion medium. was measured without ultrasonic irradiation.

In the powder dispersant composition for a hydraulic composition of the present invention, the ratio of particles having a particle size of 1 μm or more and 250 μm or less is 90 mass from the viewpoint of kneadability when it is made into a hydraulic composition and handling of the powder dispersant. % or more, preferably 93 mass % or more, more preferably 96 mass % or more, and 100 mass % or less, more preferably 99.5 mass % or less, still more preferably 99.0 mass % or less. This ratio was measured using a laser diffraction/scattering particle size distribution analyzer LA-300 (manufactured by Horiba, Ltd.) using ethanol (ethanol (95), manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) as a dispersion medium. It is calculated based on particle size results measured under irradiation.

The copolymer (I) is a copolymer having a structural unit (1) represented by the formula (1) and a structural unit (2) represented by the formula (2).

Regarding the structural unit (1) represented by the formula (1), R ¹ is a hydrogen atom or a methyl group, and preferably contains a methyl group. M is a hydrogen atom, alkali metal, alkaline earth metal, ammonium or organic ammonium, preferably alkali metal or alkaline earth metal. Two or more kinds of structural units (1) may be used. Monomers that form the structural unit (1) include monomers selected from acrylic acid, methacrylic acid, and salts thereof.

Regarding the structural unit (2) represented by the formula (2), from the viewpoint of reactivity, R ² and R ⁴ are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, From the viewpoint of increasing the fluidity of a hydraulic composition, an alkyl group having 1 carbon atom, that is, a methyl group, is preferable. Moreover, R ³ is a hydrogen atom or a methyl group, preferably a hydrogen atom, from the viewpoint of increasing the fluidity of the hydraulic composition. Two or more kinds of structural units (2) may be used. p represents a number of 0 or more and 2 or less, preferably 0 or more and 1 or less, more preferably 0, from the viewpoint of increasing the fluidity of the hydraulic composition. q represents a number of 0 or 1, preferably 1 from the viewpoint of increasing the fluidity of the hydraulic composition. n is the average number of added moles, and indicates a number of 5 or more and 150 or less. n is preferably 20 or more, more preferably 40 or more, and still more preferably 60 or more, from the viewpoint of increasing the fluidity of the hydraulic composition. And n is preferably 140 or less, more preferably 130 or less, and still more preferably 120 or less. Examples of the monomer that constitutes the structural unit (2) include monomers selected from methoxypolyethylene glycol monomethacrylate, polyoxyethylenemethallyl ether, polyoxyethylene isoprenyl ether and polyoxyethylene vinyl ether.

The molar ratio of the structural unit (1) and the structural unit (2) in the copolymer (I) is the structural unit (1)/structural unit (2) from the viewpoint of increasing the fluidity of the hydraulic composition. , preferably 1 or more, more preferably 3 or more, and preferably 10 or less, more preferably 9 or less.

The weight-average molecular weight of the copolymer (I) is preferably 20,000 or more, more preferably 25,000 or more, still more preferably 30,000 or more, from the viewpoint of increasing the fluidity of the hydraulic composition. Even more preferably 35,000 or more, and preferably 70,000 or less, more preferably 60,000 or less, and even more preferably 55,000 or less. This weight average molecular weight is measured by gel permeation chromatography (GPC) under the following conditions.
* GPC conditions Equipment: GPC (HLC-8320GPC) manufactured by Tosoh Corporation Column: G4000PWXL + G2500PWXL (manufactured by Tosoh Corporation)
Eluent: 0.2M phosphate buffer/ _CH3CN =9/1
Flow rate: 1.0 mL/min
Column temperature: 40°C
Detection: RI
Sample size: 0.2 mg/mL
Standard substance: polyethylene glycol conversion (monodisperse polyethylene glycol: molecular weight 87,500, 250,000, 145,000, 46,000, 24,000)

The copolymer (I) may have a structural unit other than the structural unit (1) and the structural unit (2) [hereinafter referred to as structural unit (3)]. Optional monomers for the structural unit (3) include ethylene glycol methacrylate phosphate, methyl acrylate, and 2-hydroxyethyl acrylate.

The total proportion of the structural unit (1) and the structural unit (2) in the total structural units of the copolymer (I) is preferably 80 mol% or more, more preferably 90 mol% or more, and preferably 100 mol. % or less, and may be 100 mol %.

The total proportion of the structural unit (1) and the structural unit (2) in the total structural units of the copolymer (I) is preferably 80% by mass or more, more preferably 90% by mass or more, and preferably 100% by mass. % or less, and may be 100% by mass.

The proportion of methallylsulfonic acid or a salt thereof in the total structural units of the copolymer (I) is preferably 1 mol % or less, more preferably 0, from the viewpoint of increasing the fluidity of the hydraulic composition. .5 mol% or less, more preferably 0.1 mol% or less, even more preferably 0.05 mol% or less, even more preferably 0.01 mol% or less, even more preferably substantially free, i.e., more More preferably substantially 0 mol %, still more preferably 0 mol %.
In addition, the proportion of polyamide polyamine in all structural units of the copolymer (I) is preferably 1% by mol or less, more preferably 0.1% by mol, from the viewpoint of increasing the fluidity of the hydraulic composition. 5 mol% or less, more preferably 0.1 mol% or less, even more preferably 0.05 mol% or less, even more preferably 0.01 mol% or less, even more preferably substantially free, that is, even more Preferably it is substantially 0 mol %, and even more preferably 0 mol %.

The powder dispersant composition for a hydraulic composition of the present invention contains the copolymer (I) in an effective content of preferably 80% by mass or more, more preferably 90% by mass or more, and preferably 100% by mass. 95% by mass or less, more preferably 95% by mass or less. The powdery dispersant composition for hydraulic composition of the present invention may comprise the copolymer (I).

The powder dispersant composition for hydraulic composition of the present invention can contain components other than the copolymer (I). For example, a powdering aid can be included. Powdering aids include inorganic powders. Examples of inorganic powders include silicon oxides, salts of silicon oxides, and carbonates. Organic powders such as polyethylene glycol can also be used. When a powdering aid is contained, its content is preferably 1% by mass or more, more preferably 5% by mass or more, and preferably 40% by mass, in terms of effective content, relative to the copolymer (I). % or less, more preferably 20 mass % or less. The powder dispersant composition for hydraulic composition of the present invention may comprise the copolymer (I) and a powdering aid.

Other components that can be contained in the powder dispersant composition for hydraulic composition of the present invention include, for example, powder antifoaming agents, powder shrinkage reducing agents, powder thickeners and the like. Examples of powdered antifoams and powdered shrinkage reducing agents include polyoxyalkylene glycol alkyl ethers. Examples of powder thickeners include cellulose derivatives such as hydroxypropylmethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose and the like. When a component selected from a powder antifoaming agent, a powder shrinkage reducing agent and a powder thickening agent is contained, the content thereof is preferably 1% by mass or more in terms of effective content with respect to copolymer (I), More preferably 5% by mass or more, preferably 40% by mass or less, and more preferably 20% by mass or less. The powder dispersant composition for a hydraulic composition of the present invention may comprise the copolymer (I) and a component selected from a powder antifoaming agent, a powder shrinkage reducing agent and a powder thickening agent. .

The powder dispersant composition for hydraulic compositions of the present invention can be applied to various hydraulic compositions. The hydraulic composition is preferably a cement-containing hydraulic composition. Examples of hydraulic compositions include those containing hydraulic powder and water. The hydraulic composition has a water/hydraulic powder mass ratio of, for example, 10 mass % or more, further 20 mass % or more, and 50 mass % or less, further 40 mass % or less. That is, the powder dispersant composition for a hydraulic composition of the present invention may be for a hydraulic composition having a water/hydraulic powder mass ratio of 50% by mass or less.

Copolymer (I) comprises a monomer to be a structural unit (1), a monomer to be a structural unit (2), and optionally any monomer copolymerizable therewith by a known method. Obtained by copolymerization. By carrying out the copolymerization in a reaction medium containing water, a reaction product containing water and copolymer (I) is obtained. The powder dispersant composition for hydraulic composition of the present invention can be obtained by drying a mixture containing copolymer (I) and water, for example, the reaction product. Said mixture is preferably an aqueous solution. The mixture, for example, the aqueous solution can be dried by heat drying or vacuum drying, and heat drying is preferable from the viewpoint of productivity of the dried product. Drying of the aqueous solution can be performed by a method such as a thin film drying method, a spray drying method, or a stirring drying method. Examples of the thin film drying method include a drum drying method, a disk drying method, and a belt drying method. Drying of the mixture, for example, the aqueous solution can be carried out by heat drying. Moreover, the drying of the mixture, for example, the aqueous solution can be performed by a thin film drying method or a spray drying method. The obtained powder can be used as it is or after particle size adjustment such as sieving, as the powdery dispersant composition for hydraulic composition of the present invention.

When producing the powder dispersant composition for a hydraulic composition of the present invention, the copolymer (I) and water are contained from the viewpoint of increasing the ease of pulverization and the fluidity of the hydraulic composition. The reaction product can be dried by adjusting the pH of the mixture, for example, as follows.
(1) When the copolymer (I) is a copolymer in which n of the structural unit (2) is less than 40, the pH of the mixture containing the copolymer (I) and water is adjusted to 11 or more and 14 or less. dry.
(2) When the copolymer (I) is a copolymer in which n of the structural unit (2) is 40 or more and less than 80, the pH of the mixture containing the copolymer (I) and water is adjusted to 9 or more and 14 Dry as follows.
(3) When the copolymer (I) is a copolymer in which n of the structural unit (2) is 80 or more and less than 150, the pH of the mixture containing the copolymer (I) and water is adjusted to 7 or more and 14 Dry as follows.
The pH of the mixture, for example, the aqueous solution containing copolymer (I) and water can be measured by the measuring method shown in the Examples.

<Example 1 and Comparative Example 1>
(1) Copolymer The following copolymer 1 was used.
Copolymer 1: methacrylic acid / methoxypolyethylene glycol (120) monomethacrylate = 90 mol / 10 mol (average number of moles added in parentheses, hereinafter the same), weight average molecular weight = 39,000 (effective solid content 40%)

(2) Production of Powder Dispersant Composition for Hydraulic Composition The monomers of Copolymer 1 were reacted by a conventional method to obtain an aqueous solution containing 40% by mass of Copolymer 1. This aqueous solution was dried by the following method to produce a powdery dispersant composition for a hydraulic composition.

(2-1) Production by Spray Drying Method An aqueous solution containing the copolymer 1 and water was prepared as described above. This aqueous solution had a copolymer solid content concentration of 40% by mass and a pH (25° C.) of 3. A 48% sodium hydroxide aqueous solution (manufactured by Kanto Kagaku Co., Ltd.) was added thereto to adjust the pH as shown in Table 1 to prepare various dispersant aqueous solutions. The pH of the aqueous solution and the aqueous solution for dispersant was measured at 25° C. with an electrode-type pH meter (manufactured by HORIBA, Ltd.). Hereinafter, the pH measurement was performed in accordance with the same method in other examples and comparative examples. The types of copolymers used are also shown in Table 1.

The aqueous solution for a dispersant was spray-dried in a practical powdering equipment.
The pulverizing equipment used was equipped with a disk atomizer, a blower and a dryer. The dryer inlet temperature was 150°C, the outlet temperature was 80°C, the outside temperature was 20°C, and the disk atomizer rotation speed was 18,000 rpm. rice field. The sprayed dried product was passed through a 1,000 μm mesh sieve to remove coarse particles and foreign matter, and used as a powder dispersant for the test.
Comparative products 1-1 and 1-2 and invention products 1-3, 1-4 and 1-5 were produced by the spray drying method under these conditions.

(2-2) Production by Drum Drying Method The aqueous solution for dispersing agent was formed into a sheet by an actual drum drying facility. The powdering equipment used was equipped with a drying drum and a scraper, and had a drying drum area of 6.2 m ² , a drying drum rotation speed of 3.1 rpm, a drying drum temperature of 130°C and an ambient temperature of 30°C. Subsequently, the obtained sheet was cooled with an actual drum cooling equipment and pulverized with a feather mill. A cooling facility was installed near the pulverization facility so that the sample sheet scraped from the drum drying facility by the scraper was subsequently conveyed to the cooling facility. The cooling equipment used had a cooling drum, and the cooling drum area was 5.8 m ² , the cooling drum rotation speed was 1.5 rpm, the cooling drum temperature was 22°C, and the outside air temperature was 30°C. The dried product after pulverization was sifted through a 700 μm mesh sieve to remove coarse particles and foreign matter, and then classified using a 250 μm or 100 μm mesh sieve as necessary, and used as a powder dispersant for the test. Powder dispersants other than the powder dispersant produced by the spray drying method were produced by the drum drying method under these conditions.

(3) Powder dispersant particle size distribution measurement using a particle size distribution meter. Using, ethanol (95) (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) was used as a dispersion medium to measure the particle size distribution, and the median diameter (D50; μm) and the ratio of particles with a particle size of 1 μm or more and 250 μm or less ( %) was measured and calculated. Table 2 shows the results.

(4) Mortar test (4-1) Preparation of mortar A mortar was prepared with the following mortar composition. The mortar was prepared by kneading the ingredients (60 rpm, 120 seconds) using a mortar mixer specified in JISR 5201. At that time, the powdery dispersant composition for a hydraulic composition shown in Table 2 was added in the amount shown in Table 2 by dry-mixing in advance into the cement.
<Combination of mortar>
・ Cement: 700 g (Ordinary Portland cement manufactured by Taiheiyo Cement Co., Ltd., specific gravity 3.16)
・Fine aggregate: 700 g (sand, produced in Joyo, Kyoto Prefecture, surface dry specific gravity 2.50 g/cm ³ )
・Tap water: 245g
・W/C: 35%

(4-2) Evaluation of Mortar Fluidity The mortar immediately after kneading prepared above was filled in a flow cone (upper diameter 70 mm×lower diameter 100 mm×height 60 mm) described in JISR 5201, and the mortar flow was measured. Table 2 shows the results.

*1 In Table 2, the addition amount of the powdery dispersant composition for hydraulic composition is parts by mass with respect to 100 parts by mass of cement (the same shall apply hereinafter).

Examples showed superior initial fluidity (dispersibility of hydraulic powder) compared to Comparative Examples. This is because the powdery dispersant composition for hydraulic composition of the present invention used in the examples has improved solubility in water due to its small diameter, and effectively disperses the hydraulic powder. be considered.

<Example 2 and Comparative Example 2>
A powdery dispersant composition for a hydraulic composition was produced in the same manner as in Example 1, except that the following copolymer 2 was used as the copolymer and the pH was shown in Table 3 by spray drying. Table 3 shows the results. Further, a mortar test was conducted in the same manner as in Example 1 using the powdery dispersant compositions for hydraulic compositions in Table 3. Table 4 shows the results.
Copolymer 2: acrylic acid / methacrylic acid / methoxypolyethylene glycol (45) monomethacrylate = 35 mol / 35 mol / 30 mol (average added mole number in parentheses, hereinafter the same), weight average molecular weight = 40,000 ( effective solid content 40%)

<Example 3 and Comparative Example 3>
A powdery dispersant composition for a hydraulic composition was produced in the same manner as in Example 1, except that Copolymer 3 below was used as the copolymer and the pH shown in Table 5 was subjected to spray drying. Table 5 shows the results. Further, a mortar test was conducted in the same manner as in Example 1 using the powdery dispersant composition for hydraulic composition in Table 5. Table 6 shows the results.
Copolymer 3: methacrylic acid/methoxypolyethylene glycol (25) monomethacrylate = 75 mol/25 mol, weight average molecular weight = 50,000 (effective solid content 40%)

<Example 4 and Comparative Example 4>
Using the powder dispersant compositions for hydraulic compositions produced in Example 1 and Comparative Example 1, the same test as in Example 1 was performed on mortars having the following formulations. Table 7 shows the results.
The mortar was prepared by kneading the ingredients (60 rpm, 300 seconds) using a mortar mixer specified in JIS R 5201. At that time, the powdery dispersant composition for a hydraulic composition shown in Table 7 was added in the amount shown in Table 7 by dry-mixing in advance into the cement. In addition, the transition state of the mixed system during kneading was visually observed, and the elapsed time from the start of kneading at the time when it was judged that the transition to the slurry state (the moment when the mortar became a lump as slurry) was calculated. Recorded as time.
<Combination of mortar>
・ Cement: 700 g (high-early-strength Portland cement manufactured by Taiheiyo Cement Co., Ltd., specific gravity 3.16)
・Fine aggregate: 700 g (sand, produced in Joyo, Kyoto Prefecture, surface dry specific gravity 2.50 g/cm ³ )
・Tap water: 161g
・W/C: 23%

The examples showed excellent initial fluidity (dispersibility of hydraulic powder) and kneadability (shortened kneading time) compared to the comparative examples. This is because the powder dispersant composition for a hydraulic composition of the present invention used in the examples has improved solubility in water due to its small diameter, and can effectively form a hydraulic powder even at a relatively low water ratio. is considered to be due to the dispersion of

<Example 5 and Comparative Example 5>
A mortar test and measurement of the kneading time were carried out in the same manner as in Example 4, except that the copolymer 2 was used as the copolymer. Table 8 shows the results.

<Example 6 and Comparative Example 6>
A mortar test and measurement of the kneading time were carried out in the same manner as in Example 4, except that the copolymer 3 was used as the copolymer. Table 9 shows the results.

Claims (5)

A powder dispersant composition for a hydraulic composition containing a copolymer having a structural unit (1) represented by the following formula (1) and a structural unit (2) represented by the following formula (2), ,
Median diameter (D50) is 1 μm or more and 90 μm or less,
The proportion of particles with a particle size of 1 μm or more and 250 μm or less is 96% by mass or more and 100% by mass or less ,
80% by mass or more of the copolymer is contained in the composition,
The total proportion of the structural unit (1) and the structural unit (2) in the total structural units of the copolymer is 80 mol% or more.
A powder dispersant composition for a hydraulic composition.

(wherein R ¹ and R ³ are the same or different and each represent a hydrogen atom or a methyl group, R ² and R ⁴ each represent a methyl group , M is a hydrogen atom, an alkali metal, represents an alkaline earth metal, ammonium or organic ammonium, p represents a number of 0 or more and 2 or less, q represents a number of 0 or 1, n represents an average number of added moles, and represents a number of 5 or more and 150 or less .) 2. The hydraulic composition according to claim 1 , wherein the molar ratio of the structural unit (1) and the structural unit (2) in the copolymer is 1 or more and 10 or less (structural unit (1)/structural unit (2)). powder dispersant composition for 3. The powder dispersant composition for a hydraulic composition according to claim 1, wherein the copolymer has a weight average molecular weight of 20,000 or more and 70,000 or less. The powder dispersant composition for a hydraulic composition according to any one of claims 1 to 3 , wherein q in formula (2) is 1. A hydraulic composition obtained by blending water, hydraulic powder, and the powdery dispersant composition for a hydraulic composition according to any one of claims 1 to 4 .