JP2003277112A - Method for producing powdery cement dispersant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a powdery dispersant at a high recovery ratio without lowering its dispersion performance. <P>SOLUTION: In the method for producing the powdery dispersant, an aqueous solution containing the following A component in 5 to 40 mass% is introduced into a spray drier in which a spray apparatus part is provided with a disk atomizer, and is sprayed and dried at a hot air inlet temperature of 150 to 250°C and a hot air outlet temperature of 80 to 150°C: the A component is a water soluble vinyl copolymer containing the following A1 component in 40 to 85 mol%, the A2 component in 15 to 60 mol%, and the A3 component in 0 to 5 mol% (100 mol% in total) and having a number average molecular weight of 2,000 to 50,000: the A1 component is one or more selected from olefin monocarboxylic acid and a salt thereof; the A2 component is one or more selected from alkoxypolyethylene glycol(meth)acrylate and (meth)allylsulfonate; and the A3 component is one or more selected from alkyl (meth)acrylate and hydroxyalkyl(meth)acrylate. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a powdery cement dispersant used for producing mortar and concrete, particularly for producing cement-based premix products.

[0002]

2. Description of the Related Art In recent years, examples of using a dispersant containing a polycarboxylic acid type polymer as a main component as a cement dispersant capable of obtaining good fluidity even at a low water cement ratio Is increasing. However, since such a dispersant is generally produced as an aqueous solution, it is impossible to premix it into a premix product such as a plasterer material, and there is a drawback that it is more costly than a powdered dispersant in transportation and the like. there were. In addition, the powdered dispersants of naphthalene sulfonate formaldehyde condensate and melamine sulfonate formaldehyde condensate, which are widely used at present, contain the formaldehyde which is pointed out to be carcinogenic by the International Agency for Research on Cancer (IARC). Since it may be contained, a powdery dispersant containing a polycarboxylic acid polymer compound as a main component is desired from the viewpoint of safety. Therefore, as a method for producing a powdery dispersant containing a polycarboxylic acid polymer as a main component, a method of mixing an aqueous dispersant solution and an inorganic powder and spray-drying has been proposed (JP-A-6-239652). However, if pulverization is attempted satisfactorily, the mixing amount of the inorganic powder increases and the polycarboxylic acid-based polymer compound concentration decreases, or the polymer compound that is adsorbed by the inorganic powder and elutes in the concrete liquid phase is generated. Tended to decrease. Further, when an attempt is made to produce a powdery dispersant having a high concentration of a polycarboxylic acid type polymer compound, the polymer compound adheres to the inner wall of the spray dryer to lower the recovery rate of the powdery dispersant, and to prevent thermal denaturation. However, there was a problem that the dispersion performance deteriorated.

[0003]

DISCLOSURE OF THE INVENTION In view of such circumstances, the present inventor has conducted diligent research, and as a result, if an aqueous solution of a polycarboxylic acid-based polymer compound having a specific structure was spray-dried under specific conditions, the dispersion performance was improved. The present invention was completed by finding that a powdery dispersant can be obtained with a high recovery rate without a decrease in That is, the present invention introduces an aqueous solution containing 5 to 40% by mass of the following component A into a spray dryer equipped with a disk atomizer in the spray device part, and a hot air inlet temperature of 150 to 250 ° C. and a hot air outlet temperature of 80 to Provided is a method for producing a powdery cement dispersant characterized by spray drying in a temperature range of 150 ° C. Component A: 40 to 85 mol% of the following A1 component and 15 to 60 mol of A2 component. % And A3 component 0 to 5 mol% (total 100 mol%), and a number average molecular weight of 2000 to 50,000 water-soluble vinyl copolymer: A1 component: one selected from olefin monocarboxylic acid and salts thereof or Two or more A2 components: selected from alkoxy polyethylene glycol (meth) acrylate and (meth) allyl sulfonate One or more A3 components: selected from alkyl (meth) acrylate and hydroxyalkyl (meth) acrylate One or two or more that.

[0004]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below. A1
As the olefin monocarboxylic acid as a component, acrylic acid and methacrylic acid are preferable. As the olefin monocarboxylic acid salt, a salt selected from alkali metal salts such as lithium, sodium and potassium, alkaline earth metal salts such as calcium and magnesium, and organic amine salts such as diethanolamine and triethanolamine can be used.

The alkoxypolyethylene glycol (meth) acrylate as the component A2 includes monoalkoxy polyethylene glycols having 1 to 3 carbon atoms such as monomethoxy polyethylene glycol, monoethoxy polyethylene glycol and mono (iso) propoxy polyethylene glycol. Examples thereof include esters with (meth) acrylic acid, and of these, methoxypolyethylene glycol (meth) acrylate having an oxyethylene group repeating number of 5 to 100 is preferable. If the number of repetitions is less than 5, the dispersibility is insufficient, and if it exceeds 100, a solid having a high melting point is formed, which makes handling difficult. As the (meth) allyl sulfonic acid salt of the component A2, an alkali metal salt, an alkaline earth metal salt, an organic amine salt of (meth) allyl sulfonic acid can be used. In the present invention, as the A2 component, one or more selected from alkoxypolyethylene glycol (meth) acrylate and (meth) allyl sulfonate can be used.

Examples of the alkyl (meth) acrylate as the A3 component include methyl (meth) acrylate and ethyl (meth) acrylate. Examples of hydroxyalkyl (meth) acrylates include 2-hydroxyethyl (meth) acrylate and 3-hydroxypropyl (meth) acrylate.

The content of the water-soluble vinyl copolymer as the component A is 5 to 40% by mass, preferably 20 to 40% by mass. If this content is less than 5% by mass, the energy cost required for water evaporation will be high and it is not economical, and if it exceeds 40% by mass, it will be dried in a stringing state and the bulk specific gravity of the powder will increase,
Liquidity decreases.

The A1 component in the A component is 40 to 85 mol%, preferably 45 to 80 mol%, the A2 component is 15 to 60 mol%, preferably 20 to 55 mol%, and the A3 component is 0 to 50 mol%. It is 5 mol%, preferably 0 to 3 mol%. Dispersion performance tends to decrease outside these ranges. Particularly, from the viewpoint of dispersion performance and recovery rate, methacrylic acid or a salt thereof as an A1 component is 55 to 75
A water-soluble vinyl copolymer containing 25 to 45 mol% of methoxypolyethylene glycol (meth) acrylate as the A2 component (total of 100 mol% of the A1 component and the A2 component) is preferable, and methacrylic acid or a salt thereof is used as the A1 component. 50-72 mol
%, 25 to 40 mol% of methoxy polyethylene glycol (meth) acrylate as the A2 component and 0.1 to 10 mol% of (meth) allyl sulfonate (total of the A1 component and the A2 component is 100%).
A water-soluble vinyl copolymer containing (mol%) is more preferable.

The water-soluble vinyl copolymer has a number average molecular weight of 20.
It is from 00 to 50000, preferably from 3000 to 40,000. Outside this range, the dispersion performance tends to decrease. In the present invention, the number average molecular weight is a pullulan conversion value by the GPC method.

In the present invention, as the spray dryer, a publicly known spray dryer provided with a disk atomizer in the spray device portion can be used. As the drying conditions, a temperature range of hot air inlet temperature of 150 to 250 ° C, preferably 160 to 230 ° C, and hot air outlet temperature of 80 to 150 ° C, preferably 90 to 130 ° C is used. If the hot air inlet temperature is lower than 150 ° C, the productivity will decrease, and if it exceeds 250 ° C, the thermal denaturation will cause the dispersion performance to decrease. Hot air outlet temperature 80 ℃
If it is less than 1, the water content of the powder tends to be high and lumps are likely to occur, and if it exceeds 150 ° C, the productivity is deteriorated and the dispersion performance is deteriorated due to thermal denaturation.

Examples of the cement which can use the powdery dispersant of the present invention include ordinary Portland cement, early-strength Portland cement, moderate heat Portland cement, high belite Portland cement, blast furnace cement, fly ash-containing cement, and silica fume-containing cement. . If necessary, the powdery cement dispersant according to the present invention may be used together with an additive such as a hardening accelerator, a retarder, a thickener, a waterproofing agent, a shrinkage reducing agent, a swelling agent, an antifoaming agent and an AE agent. You can also

The embodiments of the present invention are as follows.
5) are mentioned. 1) In a spray dryer equipped with a disk atomizer, the rotation speed of the disk atomizer was 24000 rpm while maintaining the hot air inlet temperature of 200 ° C and the hot air outlet temperature of 95 ° C.
So, methacrylic acid sodium salt / methoxy polyethylene glycol (n = 23) methacrylate = 70/30
The concentration of the vinyl copolymer a1 having a number average molecular weight of 23,000 obtained by the copolymerization reaction at a ratio of (mol% ratio) is 40% by mass.
A method for producing a powdery cement dispersant P1 having an average particle diameter of 70 μm by spray-drying the aqueous solution at a flow rate of 125 kg / hr.

2) In a spray dryer equipped with a disk atomizer, a hot air inlet temperature of 190 ° C. and a hot air outlet temperature of 85
Rotation speed of disk atomizer 24 while maintaining at ℃ 24
Number average molecular weight 3 obtained by copolymerization reaction at a ratio of calcium methacrylate / methoxy polyethylene glycol (n = 45) methacrylate / methallyl sulfonic acid sodium salt = 65/30/5 (mole% ratio) at 000 rpm.
A 38% by weight aqueous solution of 3500 vinyl copolymer a2 was spray-dried at a flow rate of 121 kg / hr to give an average particle size of 69.
A production method for obtaining a powdery cement dispersant P2 having a size of μm.

3) In a spray dryer equipped with a disk atomizer, a hot air inlet temperature of 200 ° C. and a hot air outlet temperature of 95
Rotation speed of disk atomizer 24 while maintaining at ℃ 24
Number average molecular weight 1 obtained by copolymerization reaction at a ratio of methacrylic acid sodium salt / methoxy polyethylene glycol (n = 23) methacrylate / methallyl sulfonic acid sodium salt = 58/35/7 (mole% ratio) at 000 rpm.
An aqueous solution of 6500 vinyl copolymer a3 having a concentration of 39% by mass was spray-dried at a flow rate of 125 kg / hr to give an average particle diameter of 77.
A method for producing a powdery cement dispersant P3 having a diameter of μm.

4) In a spray dryer equipped with a disk atomizer, a hot air inlet temperature of 220 ° C. and a hot air outlet temperature of 11
Rotation speed of disk atomizer 1 while maintaining at 5 ℃
At 8000 rpm, sodium methacrylic acid salt / methoxy polyethylene glycol (n = 45) methacrylate /
Acrylic acid methyl ester = 65/32/3 (mol%
The number average molecular weight of 85 obtained by the copolymerization reaction
Of vinyl copolymer a4 having a concentration of 37% by mass,
Spray dried at a flow rate of 120 kg / hr, average particle size 65 μm
A method for producing the powdery cement dispersant P4.

5) In a spray dryer equipped with a disk atomizer, a hot air inlet temperature of 240 ° C. and a hot air outlet temperature of 13
Rotation speed of disk atomizer 1 while maintaining at 0 ℃
Obtained by copolymerization reaction at a rate of sodium acrylate / methoxy polyethylene glycol (n = 23) methacrylate / sodium methallyl sulfonate / hydroxyethyl methacrylate = 60/30/6/4 (mole% ratio) at 8000 rpm. A method for producing a powdery cement dispersant P5 having an average particle diameter of 69 μm by spray-drying the obtained 7% by weight aqueous solution of a vinyl copolymer a5 having a number average molecular weight of 25,000 at a flow rate of 80 kg / hr.

[0017]

EXAMPLES Synthesis Example 1 (Synthesis of Water-Soluble Vinyl Copolymer a1) 590 parts of water was charged into a 200 L glass-lined reaction vessel and heated while stirring to keep the internal temperature at 60 ° C. A reaction vessel containing a mixture of methacrylic acid 60 parts, methoxypolyethylene glycol (oxyethylene group repetition number n = 23) methacrylate 334 parts and 3-mercaptopropionic acid 4.7 parts and 25% 20% aqueous sodium persulfate solution for 2 hours. Was added dropwise. Next, add 10 parts of a 20% aqueous sodium persulfate solution to 3 parts.
Drop over 0 minutes, age at the same temperature for 2 hours, and then at 80 ℃
The temperature was raised to and aged for 2 hours. Next, 58 parts of 48% NaOH was added dropwise while flowing cooling water to the jacket to neutralize the reaction solution. This reaction solution contains 70 mol of sodium methacrylic acid.
%, Methoxypolyethylene glycol (n = 23) methacrylate was copolymerized at a ratio of 30 mol% (total 100 mol%), and a water-soluble vinyl copolymer having a number average molecular weight of 23,000 was prepared.
It was an aqueous solution containing wt%.

Synthesis Examples 2 to 5 (water-soluble vinyl copolymer a2 to
Synthesis of a5) In the same manner as in Synthesis Example 1, water-soluble vinyl copolymers a2 to a5 were synthesized. Table 1 shows the types of monomers, the reaction ratio, the number average molecular weight of the water-soluble vinyl copolymer, and the concentration of the water-soluble vinyl copolymer.

[0019]

[Table 1]

M1: sodium methacrylic acid salt M2: calcium methacrylic acid salt M3: sodium acrylate M4: methoxy polyethylene glycol (n = 23) methacrylate M5: methoxy polyethylene glycol (n = 45) methacrylate M6: methallyl sulfonic acid sodium salt M7: Hydroxyethyl methacrylate M8: Acrylic acid methyl ester

Example 1 (Production of powdered cement dispersant) A spray dryer having a tower diameter of 3.2 m and a height of 7.9 m was used as a spray dryer, and a disk atomizer was used as a spray device.
While maintaining the hot air inlet temperature at 200 ° C, the disk atomizer rotation speed was 24000 rpm and the water-soluble vinyl copolymer a1
Was spray-dried at a flow rate of 125 kg / hr. Table 3 shows the residual water content, average particle size, recovery rate, and number average molecular weight of the obtained powdery cement dispersant.

Examples 2 to 5 and Comparative Examples 1 to 3 (Production of Powdery Cement Dispersant) Spray drying was carried out in the same manner as in Example 1 to produce a powdery cement dispersant. Table 2 shows the drying conditions, and Table 3 shows the residual water content, average particle size, recovery rate, and number average molecular weight of the obtained powdery cement dispersant.

[0023]

[Table 2]

[0024]

[Table 3]

The average particle diameter of the powdery dispersant R3 could not be measured because it was likely to aggregate.

Paste Flow Test A performance test of the obtained powdery cement dispersant was conducted as follows. 27 parts by weight of water was added to 100 parts by weight of ordinary Portland cement, and the mixture was mixed for 3 minutes at a room temperature of 20 ° C. using a Hobart mixer to prepare a paste, and the flow value was measured. The test results are shown in Table 4. (Flow measurement method) PVC pipe with an inner diameter of 50 mm and a height of 51 mm on a polished glass plate with a thickness of 5 mm (internal volume 100 m
Place l), fill the adjusted paste, and pull up the pipe. After the spread was stopped, the diameters in two directions at right angles were measured and the average value was used as the flow value.

[0027]

[Table 4]

R4: Powder product of naphthalene sulfonate formaldehyde condensate R5: Powder product of melamine sulfonate formaldehyde condensate

[0029]

EFFECTS OF THE INVENTION According to the present invention, a powdery dispersant can be obtained with a high recovery rate without lowering the dispersion performance.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // C04B 103: 40 C04B 103: 40 (72) Inventor Masaki Ishimori 2-4-2 Daisaku Sakura, Chiba Prefecture No. 5 Central Research Institute of Taiheiyo Cement Co., Ltd. (72) Inventor Mitsuo Kinoshita 2-5 Minato-cho, Gamagori-shi, Aichi Takemoto Yushi Co., Ltd. (72) Inventor Soushi Kamoto 2-5 Minato-cho, Gamagori-shi, Aichi Takemoto Yushi Co., Ltd. F term (reference) 4J100 AJ02P AK00P AK07P AK08P AK12P AL03R AL08Q AL09R AP01Q BA05Q BA08Q BA56Q CA05 DA01 JA05 JA67

Claims (3)

[Claims] 1. An aqueous solution containing 5 to 40% by mass of the following component A is introduced into a spray dryer equipped with a disk atomizer in the spray device part, and hot air inlet temperature 150 to 250 ° C. and hot air outlet temperature 80 to 150 are provided. Method for producing a powdery cement dispersant characterized by spray drying in a temperature range of ℃: A component: 40 to 85 mol% of the following A1 component, 15 to 60 mol% of A2 component and 0 to A3 component. Water-soluble vinyl copolymer containing 5 mol% (total 100 mol%) and having a number average molecular weight of 2000 to 50,000: A1 component: one or more selected from olefin monocarboxylic acid and its salt A2 component: alkoxy One or more selected from polyethylene glycol (meth) acrylate and (meth) allyl sulfonate A3 component: One or more selected from alkyl (meth) acrylate and hydroxyalkyl (meth) acrylate. 2. Methacrylic acid or a salt thereof as an A1 component
5-75 mol%, methoxy polyethylene glycol (meth) acrylate as A2 component 25-45 mol% (A1 component and A2
2. The method for producing a powdery cement dispersant according to claim 1, which is a water-soluble vinyl copolymer containing 100% by mole of the components. 3. Methacrylic acid or a salt thereof as an A1 component
0-72 mol%, methoxy polyethylene glycol (meth) acrylate as A2 component 25-40 mol% and (meth)
2. The method for producing a powdery cement dispersant according to claim 1, which is a water-soluble vinyl copolymer containing 0.1 to 10 mol% of allyl sulfonate (total 100 mol% of A1 component and A2 component).